1.
Dehydration reaction
–
In chemistry and the biological sciences, a dehydration reaction is usually defined as a chemical reaction that involves the loss of a water molecule from the reacting molecule. Dehydration reactions are a subset of condensation reactions, because the hydroxyl group is a poor leaving group, having a Brønsted acid catalyst often helps by protonating the hydroxyl group to give the better leaving group, –OH2+. The reverse of a reaction is a hydration reaction. Common dehydrating agents used in organic synthesis include concentrated sulfuric acid, concentrated phosphoric acid, hot aluminium oxide, dehydration reactions and dehydration synthesis have the same meaning, and are often used interchangeably. Two monosaccharides, such as glucose and fructose, can be joined together using dehydration synthesis, the new molecule, consisting of two monosaccharides, is called a disaccharide. The process of hydrolysis is the reaction, meaning that the water is recombined with the two hydroxyl groups and the disaccharide reverts to being monosaccharides. In the related condensation reaction water is released two different reactants. In organic synthesis, there are examples of dehydration reaction
Dehydration reaction
2.
Drying (food)
–
Food drying is a method of food preservation in which food is dried. Drying inhibits the growth of bacteria, yeasts, and mold through the removal of water, dehydration has been used widely for this purpose since ancient times, the earliest known practice is 12,000 B. C. by inhabitants of the modern Middle East and Asia regions. Water is traditionally removed through evaporation, although today electric food dehydrators or freeze-drying can be used to speed the drying process, many different foods can be prepared by dehydration. Meat has held a significant role. For centuries, much of the European diet depended on dried cod—known as salt cod, bacalhau and it formed the main protein source for the slaves on the West Indian plantations, and was a major economic force within the triangular trade. Dried shark meat, known as Hákarl, is a delicacy in Iceland, currently popular dried meats include prosciutto, bresaola, biltong and beef jerky. Dried fruits have been consumed historically due to their sugar content and sweet taste. Fruits are often observed differently when dried, the plum becomes a prune, the grape a raisin. Figs and dates are also transformed into new, different products that can either be eaten as they are, used in recipes, freeze-dried vegetables are often found in food for backpackers, hunters, and the military. Garlic and onion are often dried, edible mushrooms, as well as other fungi, are also sometimes dried for preservation purposes or to be used as seasonings. Home drying of vegetables, fruit and meat can be carried out with electrical dehydrators or by sun-drying or by wind, preservatives such as potassium metabisulfite, BHA, or BHT may be used, but are not required. However, dried products without these preservatives may require refrigeration or freezing to ensure safe storage for a long time, industrial food dehydration is often accomplished by freeze-drying. In this case food is flash frozen and put into a system which causes the water to sublimate directly from the solid to the gaseous phase. Industrial hot air dryers are simple and easy to design, construct, more so, it is very affordable and has been reported to retain most of the nutritional properties of food if dry using appropriate drying conditions. There are many different methods for drying, each with their own advantages for particular applications, these include, National Center for Home Food Preservation, drying section
Drying (food)
–
Flattened
fish drying in the sun in
Madagascar. Fish are
preserved through such traditional methods as drying,
smoking and
salting.
Drying (food)
–
A whole potato, sliced pieces (right), and dried sliced pieces (left)
Drying (food)
–
1890 newspaper advertisement showing tin of dried coconut
Drying (food)
–
A collection of dried mushrooms
3.
Crop desiccation
–
Pre-harvest crop desiccation refers to the application of a herbicide to a crop shortly before harvest. Herbicides used include glyphosate, diquat and glufosinate, other desiccants are cyanamide, cinidon-ethyl, and pyraflufen-ethyl. Some crop may be destroyed when crop desiccation machinery moves through the field. The application of glyphosate differs between countries significantly and it is commonly used in the UK where summers are wet and crops may ripen unevenly. Thus in the UK 78% of oilseed rape is desiccated before harvest, residue quantities are regulated by Codex Alimentarius of the Food and Agriculture Organization of the United Nations. Several technical recommendations by governmental agricultural services suggest guidelines regarding sprays, as a systemic herbicide it is not a true desiccant as it can take weeks rather than days for the crop to die back after application. In the UK, it began to be applied to crops in the 1980s to control perennial weeds such as common couch which was very effective. Use as a harvest aid in the UK increased after the introduction of strobilurin fungicides which prolong the longevity of the leaves. The timing of application is crucial as the content of the grain must be below 30% for the yield of the crop to be unaffected. Yield may be affected and residues increased if applications are made to uneven fields in some areas have a moisture content over 30%. Although used in weed-free and evenly maturing crops with the aim of reducing the moisture content more rapidly to hasten the harvest. A survey of British wheat in 2006-8 found average levels of 0. 05-0.22 mg/kg with maximum levels of 1.2 mg/kg, media related to Crop desiccation at Wikimedia Commons
Crop desiccation
–
Desiccated potato plants prior to harvest
4.
Decussation
–
Decussation is used in biological contexts to describe a crossing. In anatomy the term chiasma or chiasm means nearly the same as decussation, examples include, In the brain, where nerve fibers obliquely cross from one lateral part to the other, that is to say they cross at a level other than their origin. See for examples Decussation of pyramids and sensory decussation, in botanical leaf taxology, the word decussate describes an opposite pattern of leaves which has successive pairs at right angles to each other. In effect, successive pairs of leaves cross each other, basil is a classic example of a decussate leaf pattern. In tooth enamel, where bundles of rods cross each other as they travel from the junction to the outer enamel surface. In taxonomic description where decussate markings or structures occur, names such as decussatus or decussata or otherwise in part containing decuss. are common, especially in the specific epithet. After the origin of the system, in the course of evolution from invertebrate to vertebrate. It is believed that in this process, the decussation arose with a 180° shift with respect to the brain, commissure Why does the nervous system decussate
Decussation
–
Decussate
phyllotaxis of Crassula rupestris
Decussation
–
Section of the
medulla oblongata at the level of the decussation of the pyramids.
5.
Mudcrack
–
Mudcracks are sedimentary structures formed as muddy sediment dries and contracts. Crack formation also occurs in soils as a result of a reduction in water content. Naturally forming mudcracks start as wet, muddy sediment desiccates, causing contraction, a strain is developed because the top layer tries to shrink while the material below stays the same size. When this strain becomes large enough, channel cracks form in the surface material. Individual cracks spread and join up forming a polygonal, interconnected network and these cracks may later be filled with sediment and form casts on the base of the overlying bed. Syneresis cracks can be distinguished from mudcracks because they tend to be discontinuous, sinuous, Mudcracks are generally polygonal in plan view and v-shaped in cross section. The v opens towards the top of the bed and the crack tapers downward, allen proposed a classification scheme for mud cracks based on their completeness, orientation, shape, and type of infill. Complete mudcracks form an interconnected network, the connection of cracks often occurs when individual cracks join together forming a larger continuous crack. Incomplete mudcracks are not connected to each other but still form in the region or location as the other cracks. Orthogonal intersections can have an orientation or may be random. In oriented orthogonal cracks, the cracks are usually complete and bond to one another forming irregular polygonal shapes, in random orthogonal cracks, the cracks are incomplete and unoriented therefore they do not connect or make any general shapes. Although they do not make general shapes they are not perfectly geometric, non-orthogonal mudcracks have a geometric pattern. In uncompleted non-orthogonal cracks they form as a three point star shape that is composed of three cracks. They could also form with more than three cracks but three cracks in commonly considered the minimum, in completed non-orthogonal cracks, they form a very geometric pattern. The pattern resembles small polygonal shaped tiles in a repetitive pattern, mud curls form during one of the final stages in desiccation. Mud curls commonly occur on the top layer of very thinly bedded mud rocks. When mud curls form, the water that is inside the sediment begins to evaporate causing the stratified layers to separate, the individual top layer is much weaker than multiple layers and is therefore able to contract and form curls as desiccation occurs. If transported by currents, mud curls may be preserved as mud-chip rip-up clasts
Mudcrack
–
Mud cracks in sewage
sludge in
Kos, Greece.
Mudcrack
–
Crack pattern in clay soil
Mudcrack
–
Fresh mud cracks.
Mudcrack
–
Ancient mudcracks preserved on the base of a bed of
sandstone.
6.
Jurassic
–
The Jurassic is a geologic period and system that spans 56.3 million years from the end of the Triassic Period 201.3 million years ago to the beginning of the Cretaceous Period 145 Mya. The Jurassic constitutes the middle period of the Mesozoic Era, also known as the Age of Reptiles, the start of the period is marked by the major Triassic–Jurassic extinction event. The Jurassic is named after the Jura Mountains within the European Alps, by the beginning of the Jurassic, the supercontinent Pangaea had begun rifting into two landmasses, Laurasia to the north and Gondwana to the south. This created more coastlines and shifted the continental climate from dry to humid, on land, the fauna transitioned from the Triassic fauna, dominated by both dinosauromorph and crocodylomorph archosaurs, to one dominated by dinosaurs alone. The first birds also appeared during the Jurassic, having evolved from a branch of theropod dinosaurs, other major events include the appearance of the earliest lizards, and the evolution of therian mammals, including primitive placentals. Crocodilians made the transition from a terrestrial to a mode of life. The oceans were inhabited by marine reptiles such as ichthyosaurs and plesiosaurs, the chronostratigraphic term Jurassic is directly linked to the Jura Mountains. The name Jura is derived from the Celtic root jor, which was Latinised into juria, the Jurassic period is divided into the Early Jurassic, Middle, and Late Jurassic epochs. The Jurassic System, in stratigraphy, is divided into the Lower Jurassic, Middle, the separation of the term Jurassic into three sections goes back to Leopold von Buch. The Jurassic North Atlantic Ocean was relatively narrow, while the South Atlantic did not open until the following Cretaceous period, the Tethys Sea closed, and the Neotethys basin appeared. Climates were warm, with no evidence of glaciation, as in the Triassic, there was apparently no land over either pole, and no extensive ice caps existed. In contrast, the North American Jurassic record is the poorest of the Mesozoic, the Jurassic was a time of calcite sea geochemistry in which low-magnesium calcite was the primary inorganic marine precipitate of calcium carbonate. Carbonate hardgrounds were thus very common, along with calcitic ooids, calcitic cements, the first of several massive batholiths were emplaced in the northern American cordillera beginning in the mid-Jurassic, marking the Nevadan orogeny. Important Jurassic exposures are found in Russia, India, South America, Japan, Australasia. As the Jurassic proceeded, larger and more groups of dinosaurs like sauropods and ornithopods proliferated in Africa. Middle Jurassic strata are well represented nor well studied in Africa. Late Jurassic strata are also poorly represented apart from the spectacular Tendaguru fauna in Tanzania, the Late Jurassic life of Tendaguru is very similar to that found in western North Americas Morrison Formation. During the Jurassic period, the primary living in the sea were fish
Jurassic
–
Various
dinosaurs roamed forests of similarly large
conifers during the Jurassic period.
Jurassic
–
Jurassic limestones and marls (the
Matmor Formation) in southern
Israel.
Jurassic
–
The late Jurassic
Morrison Formation in
Colorado is one of the most fertile sources of dinosaur fossils in North America.
Jurassic
–
Gigandipus, a
dinosaur footprint in the Lower Jurassic
Moenave Formation at the St. George Dinosaur Discovery Site at Johnson Farm, southwestern
Utah.
7.
Utah
–
The Utah Railway is a class III railroad operating in Utah and Colorado, and owned by Genesee & Wyoming Inc. The Utah Railway Company was incorporated on January 24,1912, with the name of Utah Coal Railway, shortened to Utah Railway in May of the same year. It was founded to haul coal from the mines to Provo, Utah, in reaction to company disappointment in the service and route of the existing Denver. In addition, the Utah Railway was the first to equip its air brakes with fourteen-pound tension springs instead of the standard seven-pound springs and these gondolas were known to the railroads employees as Battleships. Parent company Mueller Industries, a manufacturer of products, sold the Utah Railway in 2002 to Genesee & Wyoming Inc. a railroad holding company. As of January,2017, the no longer hauls coal. The Utah Railway also owns a railroad, the Salt Lake City Southern Railroad. In addition, switching services are provided in Ogden and elsewhere, the earliest logo was simply the words Utah Railway Company, spelled out on the locomotives and cabooses, and Utah Coal Route on the drop-bottom gondolas. On paper, however, the logo for many years was a circle with a white background. The wording and image in these circular logos changed over the years, the 1948 logo included the words Utah Railway surrounding a gondola with the initials U. C. R. The 1999 logo was an oval with an image of an SD diesel locomotive, in later years the symbol of the Utah Railway Company was the beehive, which is also the Utah state symbol. Genesee & Wyoming corporate website Trainwebs Utah Railway UtahRails. net Utah Railway page
Utah
–
Former Union Pacific CA-1
Caboose on display in
Helper. The Utah Railway purchased eight of these cabooses from the UP between 1918 and 1927.
Utah
8.
Dinosaur
–
Dinosaurs are a diverse group of reptiles of the clade Dinosauria that first appeared during the Triassic. Although the exact origin and timing of the evolution of dinosaurs is the subject of active research and they became the dominant terrestrial vertebrates after the Triassic–Jurassic extinction event 201 million years ago. Their dominance continued through the Jurassic and Cretaceous periods and ended when the Cretaceous–Paleogene extinction event led to the extinction of most dinosaur groups 66 million years ago, until the late 20th century, all groups of dinosaurs were believed to be extinct. As such, birds were the dinosaur lineage to survive the mass extinction event. This article deals primarily with non-avian dinosaurs, Dinosaurs are a varied group of animals from taxonomic, morphological and ecological standpoints. Birds, at over 10,000 living species, are the most diverse group of vertebrates besides perciform fish, using fossil evidence, paleontologists have identified over 500 distinct genera and more than 1,000 different species of non-avian dinosaurs. Dinosaurs are represented on every continent by both extant species and fossil remains, while dinosaurs were ancestrally bipedal, many extinct groups included quadrupedal species, and some were able to shift between these stances. Elaborate display structures such as horns or crests are common to all dinosaur groups, evidence suggests that egg laying and nest building are additional traits shared by all dinosaurs.7 meters and heights of 18 meters and were the largest land animals of all time. Still, the idea that dinosaurs were uniformly gigantic is a misconception based in part on preservation bias, as large. Many dinosaurs were small, Xixianykus, for example, was only about 50 cm long. Through the first half of the 20th century, before birds were recognized to be dinosaurs, most of the community believed dinosaurs to have been sluggish. Most research conducted since the 1970s, however, has indicated that all dinosaurs were active animals with elevated metabolisms and numerous adaptations for social interaction. The large sizes of some groups, as well as their seemingly monstrous and fantastic nature, have ensured dinosaurs regular appearance in best-selling books and films. Persistent public enthusiasm for the animals has resulted in significant funding for dinosaur science, the term is derived from the Greek words δεινός and σαῦρος. Though the taxonomic name has often interpreted as a reference to dinosaurs teeth, claws. Instead, dinosaurs, like many forms of reptile sub-groups, did not exhibit characteristics which were traditionally regarded as reptilian. Under phylogenetic nomenclature, dinosaurs are usually defined as the group consisting of Triceratops, Neornithes, their most recent common ancestor, Birds are now recognized as being the sole surviving lineage of theropod dinosaurs. In traditional taxonomy, birds were considered a class that had evolved from dinosaurs
Dinosaur
Dinosaur
–
The world's smallest dinosaur footprint, the Hunterian Museum, Glasgow.
Dinosaur
–
Triceratops horridus skeleton,
Natural History Museum of Los Angeles County
Dinosaur
–
The common
house sparrow (Passer domesticus) is often used to represent modern birds in definitions of the group Dinosauria.
9.
Drying
–
Drying is a mass transfer process consisting of the removal of water or another solvent by evaporation from a solid, semi-solid or liquid. This process is used as a final production step before selling or packaging products. To be considered dried, the product must be solid, in the form of a continuous sheet. A source of heat and an agent to remove the vapor produced by the process are often involved, in bioproducts like food, grains, and pharmaceuticals like vaccines, the solvent to be removed is almost invariably water. Desiccation may be synonymous with drying or considered a form of drying. In the most common case, a gas stream, e. g. air, applies the heat by convection, other possibilities are vacuum drying, where heat is supplied by conduction or radiation, while the vapor thus produced is removed by the vacuum system. Another indirect technique is drum drying, where a surface is used to provide the energy. In contrast, the extraction of the solvent, e. g. water, by centrifugation, is not considered drying. Usually, in period, it is surface moisture outside individual particles that is being removed. The drying rate during this period is dependent on the rate of heat transfer to the material being dried. Therefore, the maximum achievable drying rate is considered to be heat-transfer limited, if drying is continued, the slope of the curve, the drying rate, becomes less steep and eventually tends to nearly horizontal at very long times. The product moisture content is constant at the equilibrium moisture content. In the falling-rate period, water migration from the interior to the surface is mostly by molecular diffusion. This means that water moves from zones with higher moisture content to zones with lower values, if water removal is considerable, the products usually undergo shrinkage and deformation, except in a well-designed freeze-drying process. The drying rate in the period is controlled by the rate of removal of moisture or solvent from the interior of the solid being dried and is referred to as being mass-transfer limited. This is widely noticed in hygroscopic products such as fruits and vegetables, the following are some general methods of drying, Application of hot air. Air heating increases the force for heat transfer and accelerates drying. It also reduces air relative humidity, further increasing the force for drying
Drying
–
Drying of fish in Lofoten in the production of stockfish
Drying
–
In a typical
phase diagram, the boundary between gas and liquid runs from the triple point to the
critical point. Regular drying is the green arrow, while
supercritical drying is the red arrow and
freeze drying is the blue.
10.
Desiccant
–
A desiccant is a hygroscopic substance that induces or sustains a state of dryness in its vicinity. Commonly encountered pre-packaged desiccants are solids that absorb water, desiccants for specialized purposes may be in forms other than solid, and may work through other principles, such as chemical bonding of water molecules. They are commonly encountered in foods to retain crispness, industrially, desiccants are widely used to control the level of water in gas streams. Although some desiccants are chemically inert, many are extremely reactive, the most common desiccant is silica, an otherwise inert, nontoxic, water-insoluble white solid. Tens of thousands of tons are produced annually for this purpose, other common desiccants include activated charcoal, calcium sulfate, calcium chloride, and molecular sieves. One measure of desiccant efficiency is the ratio of water storable in the desiccant relative to the mass of desiccant, another measure is the residual relative humidity of the air or other fluid being dried. The performance of any desiccant varies with temperature and both relative humidity and absolute humidity, sometimes a humidity indicator is included in the desiccant to show, by color changes, the degree of water-saturation of the desiccant. One commonly used indicator is cobalt chloride, when it bonds with two water molecules, it turns purple. Further hydration results in the pink hexaaquacobalt chloride complex Cl2, one example of desiccant usage is in the manufacture of insulated windows where zeolite spheroids fill a rectangular spacer tube at the perimeter of the panes of glass. The desiccant helps to prevent the condensation of moisture between the panes, another use of zeolites is in the dryer component of air conditioning systems to help maintain the efficacy of the refrigerant. Desiccants are also used to protect goods in shipping containers against moisture damage. Hygroscopic cargo, such as cocoa, coffee, and various nuts and grains, are susceptible to mold and rot when exposed to condensation. Because of this, shippers often take measures to protect against cargo loss. Desiccants induce dryness in any environment and reduce the amount of moisture present in air, desiccants come in various forms and have found widespread use in the food, pharmaceuticals, packing, electronics and many manufacturing industries. Air conditioning systems can be based on desiccants. Desiccants are used in different kinds of livestock farming to dry newborn animals, the use of a good desiccant can help them dry quicker and save energy, which can be crucial for the animals development. Another use is to reduce bacteria and pathogens that thrive in wet surfaces, however, some desiccants have a very high pH-level, which can be harmful for an animals skin. Desiccants are also used to water from solvents, typically required by chemical reactions that do not tolerate water
Desiccant
–
Canisters are commonly filled with
silica gel and other
molecular sieves used as desiccant in drug containers to keep contents dry; shown here next to a U.S. quarter for size comparison.
Desiccant
–
Silica gel in a
sachet or porous
packet
Desiccant
–
Toluene is refluxed with
sodium and
benzophenone to produce dry, oxygen-free toluene. The toluene is dry and oxygen free when the intense blue coloration from the benzophenone ketyl radical is observed.
11.
Hygroscopic
–
Hygroscopy is the phenomenon of attracting and holding water molecules from the surrounding environment, which is usually at normal or room temperature. This is achieved through either absorption or adsorption with the absorbing or adsorbing substance becoming physically changed somewhat. Zinc chloride and calcium chloride, as well as potassium hydroxide and sodium hydroxide, are so hygroscopic that they readily dissolve in the water they absorb, not only is sulfuric acid hygroscopic in concentrated form but its solutions are hygroscopic down to concentrations of 10 Vol-% or below. A hygroscopic material will tend to damp and cakey when exposed to moist air. Because of their affinity for moisture, hygroscopic materials might require storage in sealed containers. When added to foods or other materials for the purpose of maintaining moisture content. Materials and compounds exhibit different hygroscopic properties, and this difference can lead to detrimental effects, differences in hygroscopy can be observed in plastic-laminated paperback book covers—often, in a suddenly moist environment, the book cover will curl away from the rest of the book. The unlaminated side of the cover absorbs more moisture than the side and increases in area. This is similar to the function of a thermostats bi-metallic strip, inexpensive dial-type hygrometers make use of this principle using a coiled strip. Deliquescence, the process by which a substance absorbs moisture from the atmosphere until it dissolves in the absorbed water, deliquescence occurs when the vapour pressure of the solution that is formed is less than the partial pressure of water vapour in the air. While some similar forces are at work here, it is different from capillary attraction, a process where glass or other solid substances attract water, the similar-sounding but unrelated word hydroscopic is sometimes used in error for hygroscopic. A hydroscope is a device used for making observations deep under water. The amount of moisture held by hygroscopic materials is proportional to the relative humidity. Tables containing this information can be found in engineering handbooks and is also available from suppliers of various materials and chemicals. Hygroscopy also plays an important role in the engineering of plastic materials, some plastics are hygroscopic while others are not. The seeds of grasses have hygroscopic extensions that bend with changes in humidity. An example is Needle-and-Thread, Hesperostipa comata, each seed has an awn that twists several turns when the seed is released. Increased moisture causes it to untwist, and, upon drying, to twist again, thorny dragons collect moisture in the dry desert via nighttime condensation of dew that forms on their skin and is channeled to their mouths in hygroscopic grooves between the spines of their skin
Hygroscopic
–
Apparatus for the determination of the hygroscopicity of fertilizer, Fixed Nitrogen Research Laboratory, ca.1930
Hygroscopic
–
The
thorny dragon features hygroscopic grooves between the spines of its skin to capture water in its desert habitat.
12.
Silica gel
–
Silica gel is a granular, vitreous, porous form of silicon dioxide made synthetically from sodium silicate. Silica gel contains a nano-porous silica micro-structure, suspended inside a liquid, most applications of silica gel require it to be dried, in which case it is called silica xerogel. For practical purposes, silica gel is often interchangeable with silica xerogel, silica xerogel is tough and hard, it is more solid than common household gels like gelatin or agar. It is a naturally occurring mineral that is purified and processed into either granular or beaded form, as a desiccant, it has an average pore size of 2.4 nanometers and has a strong affinity for water molecules. Silica gel is most commonly encountered in life as beads in a small paper packet. In this form, it is used as a desiccant to control humidity to avoid spoilage or degradation of some goods. Because silica gel can have added chemical indicators and absorbs moisture very well, silica gel was in existence as early as the 1640s as a scientific curiosity. It was used in World War I for the adsorption of vapors, the synthetic route for producing silica gel was patented by chemistry professor Walter A. Patrick at Johns Hopkins University in 1918. Type A - clear pellets, approximate pore diameter,2.5 nm, drying and moistureproof properties, can be used as catalyst carriers, adsorbents, separators and variable-pressure adsorbent. Type B - translucent white pellets, pore diameter,4. 5-7.0 nm, liquid adsorbents, drier and perfume carriers, also may be used as catalyst carriers, type C - translucent, micro-pored structure, raw material for preparation of silica gel cat litter. Additionally dried and screened, it forms macro-pored silica gel which is used as drier, adsorbent, silica alumina gel - light yellow, chemically stable, flame-resistant, insoluble except in alkali or hydrofluoric acid. Superficial polarity, thermal stability, performance greater than fine-pored silica gel, silica gels high specific surface area allows it to adsorb water readily, making it useful as a desiccant. Silica gel is often described as absorbing moisture, which may be appropriate when the gels microscopic structure is ignored, however, material silica gel removes moisture by adsorption onto the surface of its numerous pores rather than by absorption into the bulk of the gel. Once saturated with water, the gel can be regenerated by heating it to 120 °C for 1–2 hours, some types of silica gel will pop when exposed to enough water. This is caused by breakage of the silica spheres when contacting the water, an aqueous solution of sodium silicate is acidified to produce a gelatinous precipitate that is washed, then dehydrated to produce colorless silica gel. When a visible indication of the content of the silica gel is required. This will cause the gel to be blue when dry and pink when hydrated, an alternative indicator is methyl violet which is orange when dry and green when hydrated. Due to the connection between cancer and cobalt chloride, it has been forbidden in Europe on silica gel, in many items, moisture encourages the growth of mold and spoilage
Silica gel
–
Silica gel
Silica gel
–
Silica gel is a commonly used desiccant as beads packed in a permeable bag
13.
Cobalt(II) chloride
–
Cobalt chloride is an inorganic compound of cobalt and chlorine, with the formula CoCl2. It is usually supplied as the hexahydrate CoCl2·6H2O, which is one of the most commonly used cobalt compounds in the lab, the hexahydrate is purple, whereas the anhydrous form is sky blue. Because of the ease of the reaction, and the resulting color change. Niche uses of cobalt chloride include its role in organic synthesis, Cobalt chloride has been classified as a substance of very high concern by the European Chemicals Agency as it is a suspected carcinogen. Aqueous solutions of both CoCl2 and the contain the species 2+. In the solid state CoCl2·6H2O consists of the molecule trans- and two molecules of water of crystallization and this species dissolves readily in water and alcohol. Concentrated aqueous solutions are red at room temperature but become blue at higher temperatures, CoCl2·6H2O is deliquescent, and the anhydrous salt CoCl2 is hygroscopic, readily converting to the hydrate. Hydrated cobalt chloride is prepared from cobalt hydroxide or cobalt carbonate and hydrochloric acid, CoCO3 +2 HCl +5 H2O → Co6Cl2 + CO2 Upon heating, the hexahydrate dehydrates. Generally, aqueous solutions of cobalt chlorides behave like other cobalt salts since these solutions consist of the 2+ ion regardless of the anion, such solutions give a precipitate of CoS upon treatment with H2S. CoCl2·6H2O and CoCl2 are weak Lewis acids, the adducts are usually either octahedral or tetrahedral. In the laboratory, cobalt chloride serves as a precursor to other cobalt compounds. Reaction of the compound with sodium cyclopentadienide gives cobaltocene. This 19-electron species is a reducing agent, being readily oxidised to the yellow 18-electron cobaltacenium cation. In the presence of ammonia or amines, cobalt is readily oxidised by oxygen to give a variety of cobalt complexes. Other highly basic ligands including carbonate, acetylacetonate, and oxalate induce the formation of Co derivatives, simple carboxylates and halides do not. Unlike Co complexes, Co complexes are very slow to exchange ligands, the existence of cobalt chloride, CoCl3, is disputed, although this compound is listed in some compendia. According to Greenwood and Earnshaw, the only stable binary compounds of cobalt, stated differently, CoCl2 is unreactive toward Cl2. The stability of Co in solution is increased in the presence of ligands of greater Lewis basicity than chloride
Cobalt(II) chloride
–
Anhydrous
Cobalt(II) chloride
–
Cobalt(II) chloride
Cobalt(II) chloride
–
Hexahydrate
Cobalt(II) chloride
–
Anhydrous cobalt(II) chloride
14.
Desiccator
–
Desiccators are sealable enclosures containing desiccants used for preserving moisture-sensitive items such as cobalt chloride paper for another use. A common use for desiccators is to protect chemicals which are hygroscopic or which react with water from humidity, the contents of desiccators are exposed to atmospheric moisture whenever the desiccators are opened. It also requires time to achieve a low humidity. Desiccators are sometimes used to remove traces of water from an almost-dry sample, where a desiccator alone is unsatisfactory, the sample may be dried at elevated temperature using Abderhaldens drying pistol. In order to weigh a substance, watch glass or weighing bottles or crucibles are used, but to be accurate, the weighed object must be of the same temperature of the analytical balance. If a hotter object is placed on a balance pan this has the effect of lengthening the corresponding arm of the resulting in incorrect reading. Moreover, a hot object warms the air in contact with it, the moving air pushes the corresponding balance pan upwards and therefore the error is increased further. Conversely, if an object is weighed, a current of air flows downwards. Thus, the object must be allowed to room temperature prior to measuring on a balance. To prevent adsorption of moisture from the air, glassware is cooled in a desiccator. The lower compartment of the desiccator contains lumps of silica gel, freshly calcined quicklime, the substance needing desiccation is put in the upper compartment, usually on a glazed, perforated ceramic plate. In laboratory use, the most common desiccators are circular and made of heavy glass, there is usually a removable platform on which the items to be stored are placed. The desiccant, usually a solid such as silica gel. Colour changing silica may be used to indicate when it should be refreshed, indication gels typically change from blue to pink as they absorb moisture but other colours may be used. A stopcock may be included to permit the desiccator to be evacuated, such models are usually known as vacuum desiccators. When a vacuum is to be applied, it is a practice to criss-cross the vacuum desiccator with tape. To maintain a seal, vacuum grease is usually applied to the flanges
Desiccator
–
A vacuum desiccator (left - note the stopcock which allows a vacuum to be applied), and a desiccator (right). The blue
silica gel in the space below the platform is used as the
desiccant.
15.
Glass
–
Glass is a non-crystalline amorphous solid that is often transparent and has widespread practical, technological, and decorative usage in, for example, window panes, tableware, and optoelectronics. The most familiar, and historically the oldest, types of glass are silicate glasses based on the chemical compound silica, the primary constituent of sand. The term glass, in usage, is often used to refer only to this type of material. Many applications of silicate glasses derive from their optical transparency, giving rise to their use as window panes. Glass can be coloured by adding metallic salts, and can also be painted and printed with vitreous enamels and these qualities have led to the extensive use of glass in the manufacture of art objects and in particular, stained glass windows. Although brittle, silicate glass is extremely durable, and many examples of glass fragments exist from early glass-making cultures, because glass can be formed or moulded into any shape, it has been traditionally used for vessels, bowls, vases, bottles, jars and drinking glasses. In its most solid forms it has also used for paperweights, marbles. Some objects historically were so commonly made of glass that they are simply called by the name of the material, such as drinking glasses. Porcelains and many polymer thermoplastics familiar from everyday use are glasses and these sorts of glasses can be made of quite different kinds of materials than silica, metallic alloys, ionic melts, aqueous solutions, molecular liquids, and polymers. For many applications, like glass bottles or eyewear, polymer glasses are a lighter alternative than traditional glass, silica is a common fundamental constituent of glass. In nature, vitrification of quartz occurs when lightning strikes sand, forming hollow, fused quartz is a glass made from chemically-pure SiO2. It has excellent resistance to shock, being able to survive immersion in water while red hot. However, its high melting-temperature and viscosity make it difficult to work with, normally, other substances are added to simplify processing. One is sodium carbonate, which lowers the transition temperature. The soda makes the glass water-soluble, which is undesirable, so lime, some magnesium oxide. The resulting glass contains about 70 to 74% silica by weight and is called a soda-lime glass, soda-lime glasses account for about 90% of manufactured glass. Most common glass contains other ingredients to change its properties, lead glass or flint glass is more brilliant because the increased refractive index causes noticeably more specular reflection and increased optical dispersion. Adding barium also increases the refractive index, iron can be incorporated into glass to absorb infrared energy, for example in heat absorbing filters for movie projectors, while cerium oxide can be used for glass that absorbs UV wavelengths
Glass
–
The joining of two tubes made of
lead glass during
glass welding.
Glass
–
Moldavite, a natural glass formed by
meteorite impact, from
Besednice, Bohemia
Glass
–
Tube fulgurites
Glass
–
Quartz sand (silica) is the main raw material in commercial glass production
16.
Plastic
–
Plastic is a material consisting of any of a wide range of synthetic or semi-synthetic organic compounds that are malleable and can be molded into solid objects. Plastics are typically organic polymers of high mass, but they often contain other substances. They are usually synthetic, most commonly derived from petrochemicals, due to their relatively low cost, ease of manufacture, versatility, and imperviousness to water, plastics are used in an enormous and expanding range of products, from paper clips to spaceships. They have already displaced many traditional materials, such as wood, stone, horn and bone, leather, paper, metal, glass, and ceramic, in most of their former uses. In developed countries, about a third of plastic is used in packaging, other uses include automobiles, furniture, and toys. In the developing world, the ratios may be different - for example, the worlds first fully synthetic plastic was bakelite, invented in New York in 1907 by Leo Baekeland who coined the term plastics. Toward the end of the century, one approach to this problem was met with wide efforts toward recycling, the word plastic is derived from the Greek πλαστικός meaning capable of being shaped or molded, from πλαστός meaning molded. The common word plastic should not be confused with the technical adjective plastic, used for insulating parts in electrical fixtures, paper laminated products, thermally insulation foams. Problems include the probability of moldings naturally being dark colors, One of the most expensive commercial polymers. It forms the basis of artistic and commercial acrylic paints when suspended in water with the use of other agents, polytetrafluoroethylene – Heat-resistant, low-friction coatings, used in things like non-stick surfaces for frying pans, plumbers tape and water slides. It is more known as Teflon. Urea-formaldehyde – One of the aminoplasts and used as an alternative to phenolics. Used as an adhesive and electrical switch housings. Early plastics were bio-derived materials such as egg and blood proteins, in 1600 BC, Mesoamericans used natural rubber for balls, bands, and figurines. Treated cattle horns were used as windows for lanterns in the Middle Ages, materials that mimicked the properties of horns were developed by treating milk-proteins with lye. In the 1800s, as industrial chemistry developed during the Industrial Revolution, the development of plastics also accelerated with Charles Goodyears discovery of vulcanization to thermoset materials derived from natural rubber. Parkesine is considered the first man-made plastic, the plastic material was patented by Alexander Parkes, In Birmingham, UK in 1856. It was unveiled at the 1862 Great International Exhibition in London, parkesine won a bronze medal at the 1862 Worlds fair in London
Plastic
–
Household items made of various types of plastic
Plastic
–
A chair made with a polypropylene seat
Plastic
–
Plastic (LDPE) bowl, by GEECO, Made in England, c1950.
Plastic
–
Molded plastic food replicas on display outside a restaurant in
Japan
17.
Chemistry
–
Chemistry is a branch of physical science that studies the composition, structure, properties and change of matter. Chemistry is sometimes called the science because it bridges other natural sciences, including physics. For the differences between chemistry and physics see comparison of chemistry and physics, the history of chemistry can be traced to alchemy, which had been practiced for several millennia in various parts of the world. The word chemistry comes from alchemy, which referred to a set of practices that encompassed elements of chemistry, metallurgy, philosophy, astrology, astronomy, mysticism. An alchemist was called a chemist in popular speech, and later the suffix -ry was added to this to describe the art of the chemist as chemistry, the modern word alchemy in turn is derived from the Arabic word al-kīmīā. In origin, the term is borrowed from the Greek χημία or χημεία and this may have Egyptian origins since al-kīmīā is derived from the Greek χημία, which is in turn derived from the word Chemi or Kimi, which is the ancient name of Egypt in Egyptian. Alternately, al-kīmīā may derive from χημεία, meaning cast together, in retrospect, the definition of chemistry has changed over time, as new discoveries and theories add to the functionality of the science. The term chymistry, in the view of noted scientist Robert Boyle in 1661, in 1837, Jean-Baptiste Dumas considered the word chemistry to refer to the science concerned with the laws and effects of molecular forces. More recently, in 1998, Professor Raymond Chang broadened the definition of chemistry to mean the study of matter, early civilizations, such as the Egyptians Babylonians, Indians amassed practical knowledge concerning the arts of metallurgy, pottery and dyes, but didnt develop a systematic theory. Greek atomism dates back to 440 BC, arising in works by such as Democritus and Epicurus. In 50 BC, the Roman philosopher Lucretius expanded upon the theory in his book De rerum natura, unlike modern concepts of science, Greek atomism was purely philosophical in nature, with little concern for empirical observations and no concern for chemical experiments. Work, particularly the development of distillation, continued in the early Byzantine period with the most famous practitioner being the 4th century Greek-Egyptian Zosimos of Panopolis. He formulated Boyles law, rejected the four elements and proposed a mechanistic alternative of atoms. Before his work, though, many important discoveries had been made, the Scottish chemist Joseph Black and the Dutchman J. B. English scientist John Dalton proposed the theory of atoms, that all substances are composed of indivisible atoms of matter. Davy discovered nine new elements including the alkali metals by extracting them from their oxides with electric current, british William Prout first proposed ordering all the elements by their atomic weight as all atoms had a weight that was an exact multiple of the atomic weight of hydrogen. The inert gases, later called the noble gases were discovered by William Ramsay in collaboration with Lord Rayleigh at the end of the century, thereby filling in the basic structure of the table. Organic chemistry was developed by Justus von Liebig and others, following Friedrich Wöhlers synthesis of urea which proved that organisms were, in theory
Chemistry
–
Solutions of substances in reagent bottles, including
ammonium hydroxide and
nitric acid, illuminated in different colors
Chemistry
–
Democritus ' atomist philosophy was later adopted by
Epicurus (341–270 BCE).
Chemistry
–
Antoine-Laurent de Lavoisier is considered the "Father of Modern Chemistry".
Chemistry
–
Laboratory, Institute of Biochemistry,
University of Cologne.
18.
Humidity
–
Humidity is the amount of water vapor present in the air. Water vapor is the state of water and is invisible. Humidity indicates the likelihood of precipitation, dew, or fog, higher humidity reduces the effectiveness of sweating in cooling the body by reducing the rate of evaporation of moisture from the skin. This effect is calculated in an index table or humidex. The amount of vapor that is needed to achieve saturation increases as the temperature increases. As the temperature of a parcel of water becomes lower it will not reach the point of saturation without adding or losing water mass. The differences in the amount of vapor in a parcel of air can be quite large. For example, a parcel of air that is near saturation may contain 28 grams of water per cubic meter of air at 30 °C, there are three main measurements of humidity, absolute, relative and specific. Absolute humidity is the content of air expressed in gram per cubic meter. Relative humidity, expressed as a percent, measures the current absolute humidity relative to the maximum for that temperature, specific humidity is the ratio of the mass of water vapor to the total mass of the moist air parcel. Absolute humidity is the mass of water vapor present in a given volume of air. It does not take temperature into consideration, absolute humidity in the atmosphere ranges from near zero to roughly 30 grams per cubic meter when the air is saturated at 30 °C. Absolute humidity is the mass of the vapor, divided by the volume of the air and water vapor mixture. The absolute humidity changes as air temperature or pressure changes and this makes it unsuitable for chemical engineering calculations, e. g. for clothes dryers, where temperature can vary considerably. Mass of water per unit volume as in the equation above is defined as volumetric humidity. Because of the confusion, British Standard BS1339 suggests avoiding the term absolute humidity. Units should always be carefully checked, many humidity charts are given in g/kg or kg/kg, but any mass units may be used. The field concerned with the study of physical and thermodynamic properties of mixtures is named psychrometrics
Humidity
–
Humidity and hygrometry
Humidity
–
Paranal Observatory on
Cerro Paranal in the
Atacama Desert is one of the driest places on earth.
Humidity
–
A
hygrometer
19.
Callistemon
–
Callistemon /ˌkælᵻˈstiːmən/ is a genus of shrubs in the family Myrtaceae, first described as a genus in 1814. The entire genus is endemic to Australia but widely cultivated in other regions. Their status as a taxon is in doubt, some authorities accepting that the difference between callistemons and melaleucas is not sufficient for them to be grouped in a separate genus. Callistemon species have commonly referred to as bottlebrushes because of their cylindrical. They are mostly found in the temperate regions of Australia, especially along the east coast. However, two species are found in Tasmania and several others in the south-west of Western Australia, at least some species are drought-resistant and some are used in ornamental landscaping elsewhere in the world. The genus Callistemon was first formally described in 1814 by Robert Brown. In his description he noted that the genus includes species of Metrosideros that have inflorescence similar to that of Melaleuca. Bentham described melaleucas as having stamens united in bundles opposite the petals, in his 1864 description of Callistemon salignus in Fragmenta phytographiae Australiae, Ferdinand von Mueller noted that the difference between the genera was “entirely artificial”. George Bentham also noted in Flora Australiensis that Callistemon “passes gradually into Melaleuca, with which F. Mueller proposes to unite it. ”In 1876, Henri Ernest Baillon proposed in Histoire des Plantes that Callistemon, as well as Calothamnus and Lamarchea be merged into Melaleuca. Nevertheless, most authors had preserved the distinction between the two genera Callistemon and Melaleuca until 1998, on the basis of DNA evidence, in 2006 and 2009 Craven moved all but four callistemons to melaleuca. Those four were Callistemon forresterae, Callistemon genofluvialis, Callistemon kenmorrisonii, the new description of Melaleuca has been accepted by some herbaria but not all. For example, the Queensland Herbarium accepts Melaleuca flammea but the New South Wales Herbarium accepts Callistemon acuminatus, in 2012, Frank Udovicic and Roger Spencer transferred the newly described species of melaleuca with separate stamens to Callistemon. Their argument is that using the DNA evidence is premature, many commercial nurseries continue to use the name ‘’Callistemon’’. These species can be propagated either by cuttings, or from the seeds, flowering is normally in spring and early summer, but conditions may cause flowering at other times of the year. The obvious parts of the masses are stamens, with the pollen at the tip of the filament. Flower heads vary in colour with species, most are red, a few species release the seeds annually. Bottlebrush plants can be grown in pots and they have been grown in Europe since a specimen of Callistemon citrinus was introduced to Kew Gardens in London by Joseph Banks in 1789
Callistemon
–
Bottlebrushes
Callistemon
–
Bottlebrush seed capsules
Callistemon
–
Callistemon citrinus
Callistemon
–
Callistemon pallidus
20.
Biology
–
Biology is a natural science concerned with the study of life and living organisms, including their structure, function, growth, evolution, distribution, identification and taxonomy. Modern biology is a vast and eclectic field, composed of branches and subdisciplines. However, despite the broad scope of biology, there are certain unifying concepts within it that consolidate it into single, coherent field. In general, biology recognizes the cell as the unit of life, genes as the basic unit of heredity. It is also understood today that all organisms survive by consuming and transforming energy and by regulating their internal environment to maintain a stable, the term biology is derived from the Greek word βίος, bios, life and the suffix -λογία, -logia, study of. The Latin-language form of the term first appeared in 1736 when Swedish scientist Carl Linnaeus used biologi in his Bibliotheca botanica, the first German use, Biologie, was in a 1771 translation of Linnaeus work. In 1797, Theodor Georg August Roose used the term in the preface of a book, karl Friedrich Burdach used the term in 1800 in a more restricted sense of the study of human beings from a morphological, physiological and psychological perspective. The science that concerns itself with these objects we will indicate by the biology or the doctrine of life. Although modern biology is a recent development, sciences related to. Natural philosophy was studied as early as the ancient civilizations of Mesopotamia, Egypt, the Indian subcontinent, however, the origins of modern biology and its approach to the study of nature are most often traced back to ancient Greece. While the formal study of medicine back to Hippocrates, it was Aristotle who contributed most extensively to the development of biology. Especially important are his History of Animals and other works where he showed naturalist leanings, and later more empirical works that focused on biological causation and the diversity of life. Aristotles successor at the Lyceum, Theophrastus, wrote a series of books on botany that survived as the most important contribution of antiquity to the plant sciences, even into the Middle Ages. Scholars of the medieval Islamic world who wrote on biology included al-Jahiz, Al-Dīnawarī, who wrote on botany, biology began to quickly develop and grow with Anton van Leeuwenhoeks dramatic improvement of the microscope. It was then that scholars discovered spermatozoa, bacteria, infusoria, investigations by Jan Swammerdam led to new interest in entomology and helped to develop the basic techniques of microscopic dissection and staining. Advances in microscopy also had a impact on biological thinking. In the early 19th century, a number of biologists pointed to the importance of the cell. Thanks to the work of Robert Remak and Rudolf Virchow, however, meanwhile, taxonomy and classification became the focus of natural historians
Biology
Biology
Biology
Biology
21.
Ecology
–
Ecology is the scientific analysis and study of interactions among organisms and their environment. It is a field that includes biology, geography. Ecology includes the study of interactions that organisms have with other, other organisms. Ecosystems are composed of dynamically interacting parts including organisms, the communities make up. Ecosystem processes, such as production, pedogenesis, nutrient cycling. These processes are sustained by organisms with specific life history traits, biodiversity, which refers to the varieties of species, genes, and ecosystems, enhances certain ecosystem services. Ecology is not synonymous with environment, environmentalism, natural history and it is closely related to evolutionary biology, genetics, and ethology. An important focus for ecologists is to improve the understanding of how biodiversity affects ecological function, Ecology is a human science as well. For example, the Circles of Sustainability approach treats ecology as more than the environment out there and it is not treated as separate from humans. Organisms and resources compose ecosystems which, in turn, maintain biophysical feedback mechanisms that moderate processes acting on living and non-living components of the planet, the word ecology was coined in 1866 by the German scientist Ernst Haeckel. Ecological thought is derivative of established currents in philosophy, particularly from ethics and politics, ancient Greek philosophers such as Hippocrates and Aristotle laid the foundations of ecology in their studies on natural history. Modern ecology became a more rigorous science in the late 19th century. Evolutionary concepts relating to adaptation and natural selection became the cornerstones of modern ecological theory, the scope of ecology contains a wide array of interacting levels of organization spanning micro-level to a planetary scale phenomena. Ecosystems, for example, contain abiotic resources and interacting life forms, an ecosystems area can vary greatly, from tiny to vast. A single tree is of consequence to the classification of a forest ecosystem. Several generations of a population can exist over the lifespan of a single leaf. Each of those aphids, in turn, support diverse bacterial communities, biodiversity describes the diversity of life from genes to ecosystems and spans every level of biological organization. The term has several interpretations, and there are ways to index, measure, characterize
Ecology
–
Ecology
Ecology
Ecology
Ecology
22.
Slug
–
Slug, or land slug, is a common name for any apparently shell-less terrestrial gastropod mollusc. The word slug is often used as part of the common name of any gastropod mollusc that has no shell. Various taxonomic families of land slugs form part of quite different evolutionary lineages. Thus, the families of slugs are not closely related. The shell-less condition has arisen many times independently during the evolutionary past, of the six orders of Pulmonata, two – the Onchidiacea and Soleolifera – solely comprise slugs. A third family, the Sigmurethra, contains various clades of snails, the taxonomy of this group is in the process of being revised in light of DNA sequencing. It appears that pulmonates are paraphyletic and basal to the opisthobranchs, the family Ellobiidae are also polyphyletic. E. The upper pair is light sensing and has eyespots at the ends, mantle On top of the slug, behind the head, is the saddle-shaped mantle, and under this are the genital opening and anus. On one side of the mantle is an opening, which is easy to see when open. This opening is known as the pneumostome, tail The part of a slug behind the mantle is called the tail. Keel Some species of slugs, for example Tandonia budapestensis, have a prominent ridge running over their back along the middle of the tail and this ridge is called a keel. Foot The bottom side of a slug, which is flat, is called the foot, like almost all gastropods, a slug moves by rhythmic waves of muscular contraction on the underside of its foot. It simultaneously secretes a layer of mucus that it travels on, around the edge of the foot in some taxa is a structure called the foot fringe. Vestigial shell Most slugs retain a remnant of their shell, which is usually internalized and this organ generally serves as storage for calcium salts, often in conjunction with the digestive glands. An internal shell is present in the Limacidae and Parmacellidae, adult Philomycidae, Onchidiidae and Veronicellidae lack shells. Slugs bodies are made up mostly of water and, without a full-sized shell and they must generate protective mucus to survive. Many species are most active just after rain because of the moist ground, in drier conditions, they hide in damp places such as under tree bark, fallen logs, rocks and man-made structures, such as planters, to help retain body moisture. Like all other gastropods, they undergo torsion during development, Slugs produce two types of mucus, one is thin and watery, and the other thick and sticky
Slug
Slug
–
Various species of
British land slugs, including (from the top) the larger drawings:
Arion ater,
Kerry slug,
Limax maximus and
Limax flavus
Slug
–
An active
Ambigolimax slug in
Fremont, California
Slug
–
Deroceras juvenile with eggs
23.
Trehalose
–
Trehalose, also known as mycose or tremalose, is a natural alpha-linked disaccharide formed by an α, α-1, 1-glucoside bond between two α-glucose units. Wiggers discovered trehalose in an ergot of rye, and in 1859 Marcellin Berthelot isolated it from trehala manna, a made by weevils. It can be synthesised by bacteria, fungi, plants, and it is implicated in anhydrobiosis — the ability of plants and animals to withstand prolonged periods of desiccation. It has high water retention capabilities, and is used in food, the sugar is thought to form a gel phase as cells dehydrate, which prevents disruption of internal cell organelles, by effectively splinting them in position. Rehydration then allows normal cellular activity to be resumed without the major, trehalose is not an antioxidant, because it is a non-reducing sugar and does not contain nucleophilic groups in its molecule. However, it was reported to have antioxidant effects, extracting trehalose was once a difficult and costly process, but circa the year 2000, the Hayashibara company confirmed an inexpensive extraction technology from starch for mass production. Trehalose is used in a spectrum of applications. Trehalose is a formed by a 1, 1-glucoside bond between two α-glucose units. Because trehalose is formed by the bonding of two reducing aldehyde groups, it has no capacity to participate in the Maillard reaction, there is an industrial process where trehalose is derived from corn starch. There are at least 3 biological pathways for trehalose biosynthesis, trehalose is a nonreducing sugar formed from two glucose units joined by a 1-1 alpha bond, giving it the name of α-D-glucopyranosyl--α-D-glucopyranoside. The bonding makes trehalose very resistant to hydrolysis, and therefore is stable in solution at high temperatures. The bonding also keeps nonreducing sugars in closed-ring form, such that the aldehyde or ketone end groups do not bind to the lysine or arginine residues of proteins, trehalose is less soluble than sucrose, except at high temperatures. Trehalose forms a crystal as the dihydrate, and has 90% of the calorific content of sucrose in that form. Anhydrous forms of trehalose readily regain moisture to form the dihydrate, anhydrous forms of trehalose can show interesting physical properties when heat-treated. Trehalose aqueous solutions show a concentration-dependent clustering tendency, owing to their ability to form hydrogen bonds between one another, they self-associate in water to form clusters of various sizes. Trehalose directly interacts with nucleic acids, facilitates melting of double stranded DNA,135 Trehalase deficiency is unusual in humans, except in the Greenlandic Inuit, where it occurs in 10%-15% of the population. p. 444 In nature, trehalose can be found in animals, plants, in animals, trehalose is prevalent in shrimp, and also in insects, including grasshoppers, locusts, butterflies, and bees, in which blood-sugar is trehalose. The trehalose is then broken down into glucose by the enzyme trehalase for use
Trehalose
–
Trehalose
24.
DNA
–
Deoxyribonucleic acid is a molecule that carries the genetic instructions used in the growth, development, functioning and reproduction of all known living organisms and many viruses. DNA and RNA are nucleic acids, alongside proteins, lipids and complex carbohydrates, most DNA molecules consist of two biopolymer strands coiled around each other to form a double helix. The two DNA strands are termed polynucleotides since they are composed of simpler units called nucleotides. Each nucleotide is composed of one of four nitrogen-containing nucleobases—cytosine, guanine, adenine, or thymine —a sugar called deoxyribose, and a phosphate group. The nucleotides are joined to one another in a chain by covalent bonds between the sugar of one nucleotide and the phosphate of the next, resulting in an alternating sugar-phosphate backbone. The nitrogenous bases of the two polynucleotide strands are bound together, according to base pairing rules, with hydrogen bonds to make double-stranded DNA. The total amount of related DNA base pairs on Earth is estimated at 5.0 x 1037, in comparison the total mass of the biosphere has been estimated to be as much as 4 trillion tons of carbon. The DNA backbone is resistant to cleavage, and both strands of the double-stranded structure store the same biological information and this information is replicated as and when the two strands separate. A large part of DNA is non-coding, meaning that these sections do not serve as patterns for protein sequences, the two strands of DNA run in opposite directions to each other and are thus antiparallel. Attached to each sugar is one of four types of nucleobases and it is the sequence of these four nucleobases along the backbone that encodes biological information. RNA strands are created using DNA strands as a template in a process called transcription, under the genetic code, these RNA strands are translated to specify the sequence of amino acids within proteins in a process called translation. Within eukaryotic cells DNA is organized into structures called chromosomes. During cell division these chromosomes are duplicated in the process of DNA replication, eukaryotic organisms store most of their DNA inside the cell nucleus and some of their DNA in organelles, such as mitochondria or chloroplasts. In contrast prokaryotes store their DNA only in the cytoplasm, within the eukaryotic chromosomes, chromatin proteins such as histones compact and organize DNA. These compact structures guide the interactions between DNA and other proteins, helping control which parts of the DNA are transcribed, DNA was first isolated by Friedrich Miescher in 1869. DNA is used by researchers as a tool to explore physical laws and theories, such as the ergodic theorem. The unique material properties of DNA have made it an attractive molecule for material scientists and engineers interested in micro-, among notable advances in this field are DNA origami and DNA-based hybrid materials. DNA is a polymer made from repeating units called nucleotides
DNA
–
T7 RNA polymerase (blue) producing a mRNA (green) from a DNA template (orange).
DNA
–
The structure of the DNA
double helix. The
atoms in the structure are colour-coded by
element and the detailed structure of two base pairs are shown in the bottom right.
DNA
–
Sculpture of DNA made out of shopping carts
DNA
–
James Watson and
Francis Crick (right), co-originators of the double-helix model, with Maclyn McCarty (left).
25.
Deinococcus radiodurans
–
Deinococcus radiodurans is an extremophilic bacterium, one of the most radiation-resistant organisms known. It can survive cold, dehydration, vacuum, and acid, the name Deinococcus radiodurans derives from the Ancient Greek δεινός and κόκκος meaning terrible grain/berry and the Latin radius and durare, meaning radiation surviving. The species was formerly called Micrococcus radiodurans, as a consequence of its hardiness, it has been nicknamed Conan the Bacterium. Initially, it was placed in the genus Micrococcus, after evaluation of ribosomal RNA sequences and other evidence, it was placed in its own genus Deinococcus, which is closely related to the genus Thermus. The term Deinococcus-Thermus group is used to refer to members of Deinococcus and Thermus. Deinococcus is one genus of three in the order Deinococcales, D. radiodurans is the type species of this genus, and the best studied member. D. radiodurans was discovered in 1956 by Arthur W. Anderson at the Oregon Agricultural Experiment Station in Corvallis, experiments were being performed to determine whether canned food could be sterilized using high doses of gamma radiation. A tin of meat was exposed to a dose of radiation that was thought to all known forms of life, but the meat subsequently spoiled. The complete DNA sequence of D. radiodurans was published in 1999 by TIGR, a detailed annotation and analysis of the genome appeared in 2001. The sequenced strain was ATCC BAA-816, Deinococcus radiodurans has a unique quality in which it can repair both single- and double-stranded DNA. D. radiodurans is a large, spherical bacterium, with a diameter of 1.5 to 3.5 µm. Four cells normally stick together, forming a tetrad, the bacteria are easily cultured and do not appear to cause disease. Colonies are smooth, convex, and pink to red in color, the cells stain Gram positive, although its cell envelope is unusual and is reminiscent of the cell walls of Gram negative bacteria. D. radiodurans does not form endospores and is nonmotile and it is an obligate aerobic chemoorganoheterotroph, i. e. it uses oxygen to derive energy from organic compounds in its environment. It is often found in rich in organic materials, such as soil, feces, meat, or sewage. It is extremely resistant to ionizing radiation, ultraviolet light, desiccation, in its stationary phase, each bacterial cell contains four copies of this genome, when rapidly multiplying, each bacterium contains 8-10 copies of the genome. D. radiodurans is capable of withstanding an acute dose of 5,000 grays, or 500,000 rad, of ionizing radiation with almost no loss of viability, and an acute dose of 15,000 Gy with 37% viability. A dose of 5,000 Gy is estimated to several hundred double-strand breaks into the organisms DNA
Deinococcus radiodurans
–
Deinococcus radiodurans
26.
Mycobacterium smegmatis
–
Mycobacterium smegmatis is an acid-fast bacterial species in the phylum Actinobacteria and the genus Mycobacterium. It is 3.0 to 5.0 µm long with a shape and can be stained by Ziehl-Neelsen method. It was first reported in November 1884 by Lustgarten, who found a bacillus with the appearance of tubercle bacilli in syphilitic chancres. Subsequent to this, Alvarez and Tavel found organisms similar to that described by Lustgarten also in normal genital secretions and this organism was later named M. smegmatis. M. smegmatis is generally considered a non-pathogenic microorganism, however, in very rare cases. M. smegmatis is useful for the analysis of other Mycobacteria species in laboratory experiments. M. smegmatis is commonly used in work on the species due to its being a fast grower. M. smegmatis is a model that is easy to work with, i. e. with a fast doubling time. The time and heavy infrastructure needed to work with pathogenic species prompted researchers to use M. smegmatis as a model for mycobacterial species. This species shares more than 2000 homologous genes with M. tuberculosis and shares the same peculiar cell wall structure of M. tuberculosis and it is also capable of oxidizing carbon monoxide aerobically, as is M. tuberculosis. The discovery of plasmids, phages, and mobile genetic elements has enabled the construction of dedicated gene-inactivation, the M. smegmatis mc2155 strain is hypertransformable, and is now the work-horse of mycobacterial genetics. Furthermore, it is readily cultivatable in most synthetic or complex laboratory media and these properties make it a very attractive model organism for M. tuberculosis and other mycobacterial pathogens. M. smegmatis mc2155 is also used for the cultivation of mycobacteriophage, the complete genome of M. smegmatis has been sequenced by TIGR, and microarrays have been produced by PFGRC program, adding further to its use as a model system to study mycobacteria. This suggests that transformation in M. smegmatis is a DNA repair process, presumably a repair process. Double-strand breaks are especially threatening to bacterial viability, M. smegmatis has three options for repairing double-strand breaks, homologous recombination, non-homologous end joining, and single-strand annealing. The HR pathway of M. smegmatis is the determinant of resistance to ionizing radiation. This pathway involves exchange of information between a damaged chromosome and another homologous chromosome in the same cell and it depends on the RecA protein that catalyzes strand exchange and the ADN protein that acts as a presynaptic nuclease. HR is a repair process and is the preferred pathway during logarithmic growth
Mycobacterium smegmatis
–
Mycobacterium smegmatis
27.
Mutant
–
The natural occurrence of genetic mutations is integral to the process of evolution. The study of mutants is an part of biology, by understanding the effect that a mutation in a gene has. Although not all mutations have a phenotypic effect, the common usage of the word mutant is generally a pejorative term only used for noticeable mutations. Previously, people used the sport to refer to abnormal specimens. The scientific usage is broader, referring to any organism differing from the wild type, mutants should not be confused with organisms born with developmental abnormalities, which are caused by errors during morphogenesis. In a developmental abnormality, the DNA of the organism is unchanged, conjoined twins are the result of developmental abnormalities. Chemicals that cause developmental abnormalities are called teratogens, these may also cause mutations, chemicals that induce mutations are called mutagens. Most mutagens are also considered to be carcinogens, within any given environment, a certain species has a variety of different competitors for resources, and predators to be wary of. This applies to truly realistic environments, which are ephemeral and they are dynamic and constitute a multitude different aspects especially as seasons change. This means for a species to exist within this ecosystem, they must be able to adapt to environmental cues they are given. This gives rise to species having special advantages over others. A difference between species is prevalent in this manner and this is an example of a beneficial mutation that caused a mutant who can live within their harsh environment. This success will cause organism A to have a higher rate, thereby rapidly expanding the mutations which helped organism A to survive. This creates a new mutant of the original species. Another example of this is during the, during this massive increase in factories and other facilities, there was an influx in air pollution within many different environments. This influx caused a change in many ecosystems. The peppered-moth, shown here, had a color of white. Unfortunately because of the influx of air pollution, the trees it would hide in started turning darker and darker because of the black smock coming from the factories
Mutant
–
The
blue lobster is an example of a mutant.
Mutant
28.
Wild-type
–
Wild type refers to the phenotype of the typical form of a species as it occurs in nature. Originally, the type was conceptualized as a product of the standard normal allele at a locus, in contrast to that produced by a non-standard. Mutant alleles can vary to an extent, and even become the wild type if a genetic shift occurs within the population. Continued advancements in genetic mapping technologies have created an understanding of how mutations occur. In general, however, the most prevalent allele – i. e. the one with the highest gene frequency – is the one deemed as wild type. Wild-type alleles are indicated with a + superscript, for example w+ and vg+ for red eyes and full-size wings, manipulation of the genes behind these traits led to the current understanding of how organisms form and how traits mutate within a population. Research involving the manipulation of wild-type alleles has application in fields, including fighting disease. The genetic sequence for wild-type versus mutant phenotypes and how these genes interact in expression is the subject of much research, better understanding of these processes is hoped to bring about methods for preventing and curing diseases that are currently incurable such as infection with the herpes virus. One example of such promising research in these fields was the study examining the link between wild-type mutations and certain types of lung cancer. Research is also being done dealing with the manipulation of certain traits in viruses to develop new vaccines. This research may lead to new ways to combat deadly viruses such as the Ebola virus, research using wild-type mutations is also being done to establish how viruses transition between species to identify harmful viruses with the potential to infect humans. Selective breeding to enhance the most beneficial traits is the structure upon which agriculture is built, Genetic manipulation expedited the evolution process to make crop plants and animals larger and more disease resistant. Research into wild-type mutations has allowed the creation of modified crops that are more efficient food producers. Utilization of these wild-type mutations has led to plants capable of growing in extremely arid environments. As more is understood about these genes, agriculture will continue to become an efficient process. Amplification of advantageous genes allows the best traits in a population to be present at much higher percentages than normal and these changes have also been the reason behind certain plants and animals being almost unrecognizable when compared to their ancestral lines. – The Telegraph Wild Type Learning Activity Wild-Type vs. Mutant Genetic Background
Wild-type
–
Unlike culinary
bananas, wild-type bananas have numerous large, hard seeds.
29.
Bacillus subtilis
–
Bacillus subtilis, known also as the hay bacillus or grass bacillus, is a Gram-positive, catalase-positive bacterium, found in soil and the gastrointestinal tract of ruminants and humans. A member of the genus Bacillus, B. subtilis is rod-shaped, B. subtilis has historically been classified as an obligate aerobe, though evidence exists that it is a facultative aerobe. B. subtilis is considered the best studied Gram-positive bacterium and an organism to study bacterial chromosome replication. It is one of the champions in secreted enzyme production. Bacillus subtilis is a Gram-positive bacterium, rod-shaped and catalase-positive and it was originally named Vibrio subtilis by Christian Gottfried Ehrenberg, and renamed Bacillus subtilis by Ferdinand Cohn in 1872. B. subtilis cells are typically rod-shaped, and are about 4-10 micrometers long and 0. 25–1.0 μm in diameter, as with other members of the genus Bacillus, it can form an endospore, to survive extreme environmental conditions of temperature and desiccation. B. subtilis is a facultative anaerobe and had considered as an obligate aerobe until 1998. B. subtilis is heavily flagellated, which gives it the ability to move quickly in liquids, in terms of popularity as a laboratory model organism, B. subtilis is often considered as the Gram-positive equivalent of Escherichia coli, an extensively studied Gram-negative bacterium. This species is found in the upper layers of the soil. A2009 study compared the density of spores found in soil to that found in human feces, the number of spores found in the human gut was too high to be attributed solely to consumption through food contamination. The endospore is formed at times of stress, allowing the organism to persist in the environment until conditions become favourable. Prior to the process of sporulation the cells might become motile by producing flagella, take up DNA from the environment, under stressful conditions, such as nutrient deprivation, B. subtilis undergoes the process of sporulation. This process has very well studied and has served as a model organism for studying sporulation. B. subtilis is a model used to study bacterial chromosome replication. Replication of the circular chromosome initiates at a single locus. Replication proceeds bidirectionally and two replication forks progress in clockwise and counterclockwise directions along the chromosome, chromosome replication is completed when the forks reach the terminus region, which is positioned opposite to the origin on the chromosome map. The terminus region contains several short DNA sequences that promote replication arrest, specific proteins mediate all the steps in DNA replication. Comparison between the involved in chromosomal DNA replication in B. subtilis and in Escherichia coli reveals similarities and differences
Bacillus subtilis
–
Bacillus subtilis
Bacillus subtilis
–
Sporulating B. subtilis.
Bacillus subtilis
–
Gram-stained B. subtilis
Bacillus subtilis
–
Colonies of B. subtilis grown on a
culture dish in a
molecular biology laboratory
30.
Endospore
–
An endospore is a dormant, tough, and non-reproductive structure produced by certain bacteria from the Firmicute phylum. The name endospore is suggestive of a spore or seed-like form and it is a stripped-down, dormant form to which the bacterium can reduce itself. Endospore formation is triggered by a lack of nutrients. In endospore formation, the bacterium divides within its cell wall, one side then engulfs the other. Endospores enable bacteria to lie dormant for extended periods, even centuries, revival of spores millions of years old has been claimed. When the environment becomes more favorable, the endospore can reactivate itself to the vegetative state, most types of bacteria cannot change to the endospore form. Examples of bacteria that can form endospores include Bacillus and Clostridium, the endospore consists of the bacteriums DNA, ribosomes and large amounts of dipicolinic acid. Dipicolinic acid is a chemical that appears to help in the ability for endospores to maintain dormancy. This chemical comprises up to 10% of the dry weight. They are resistant to radiation, desiccation, high temperature, extreme freezing. Thermo-resistant endospores were first hypothesized by Ferdinand Cohn after studying Bacillus subtilis growth on cheese after boiling the cheese and his notion of spores being the reproductive mechanism for the growth was a large blow to the previous suggestions of spontaneous generation. Astrophysicist Steinn Sigurdsson said There are viable bacterial spores that have found that are 40 million years old on Earth –. Common anti-bacterial agents that work by destroying vegetative cell walls do not affect endospores, endospores are commonly found in soil and water, where they may survive for long periods of time. A variety of different microorganisms form spores or cysts, but the endospores of low G+C gram-positive bacteria are by far the most resistant to harsh conditions, some classes of bacteria can turn into exospores, also known as microbial cysts, instead of endospores. Exospores and endospores are two kinds of hibernating or dormant stages seen in classes of microorganisms. Bacteria produce a single endospore internally, the spore is sometimes surrounded by a thin covering known as the exosporium, which overlies the spore coat. The spore coat, which acts like a sieve that excludes large toxic molecules like lysozyme, is resistant to many toxic molecules, the cortex lies beneath the spore coat and consists of peptidoglycan. The core wall lies beneath the cortex and surrounds the protoplast or core of the endospore, the core contains the spore chromosomal DNA which is encased in chromatin-like proteins known as SASPs, that protect the spore DNA from UV radiation and heat
Endospore
–
A stained preparation of
Bacillus subtilis showing endospores as green and the vegetative cell as red
Endospore
–
Phase-bright endospores of
Paenibacillus alvei imaged with phase-contrast microscopy
31.
Pressurize
–
A gas compressor is a mechanical device that increases the pressure of a gas by reducing its volume. An air compressor is a type of gas compressor. Compressors are similar to pumps, both increase the pressure on a fluid and both can transport the fluid through a pipe, as gases are compressible, the compressor also reduces the volume of a gas. Liquids are relatively incompressible, while some can be compressed, the action of a pump is to pressurize. The main types of gas compressors are illustrated and discussed below and they can be either stationary or portable, can be single or multi-staged, and can be driven by electric motors or internal combustion engines. Small reciprocating compressors from 5 to 30 horsepower are commonly seen in applications and are typically for intermittent duty. Larger reciprocating compressors well over 1,000 hp are commonly found in large industrial, discharge pressures can range from low pressure to very high pressure. Another type of reciprocating compressor is the swash plate compressor, which uses pistons moved by a swash plate mounted on a shaft, household, home workshop, and smaller job site compressors are typically reciprocating compressors 1½ hp or less with an attached receiver tank. Rotary screw compressors use two meshed rotating positive-displacement helical screws to force the gas into a smaller space and these are usually used for continuous operation in commercial and industrial applications and may be either stationary or portable. Their application can be from 3 horsepower to over 1,200 horsepower, rotary screw compressors are commercially produced in Oil Flooded, Water Flooded and Dry type. The efficiency of rotary compressors depends on the air drier, rotary vane compressors consist of a rotor with a number of blades inserted in radial slots in the rotor. The rotor is mounted offset in a housing that is either circular or a more complex shape. As the rotor turns, blades slide in and out of the slots keeping contact with the wall of the housing. Thus, a series of increasing and decreasing volumes is created by the rotating blades, rotary Vane compressors are, with piston compressors one of the oldest of compressor technologies. With suitable port connections, the devices may be either a compressor or a vacuum pump and they can be either stationary or portable, can be single or multi-staged, and can be driven by electric motors or internal combustion engines. A rotary vane compressor is well suited to electric drive and is significantly quieter in operation than the equivalent piston compressor. Rotary vane compressors can have mechanical efficiencies of about 90%, rolling piston forces gas against a stationary vane. A scroll compressor, also known as pump and scroll vacuum pump
Pressurize
–
A small stationary high pressure breathing air compressor for filling scuba cylinders
Pressurize
–
A single stage centrifugal compressor
Pressurize
–
A motor-driven six-cylinder reciprocating compressor that can operate with two, four or six cylinders.
Pressurize
–
A three-stage diaphragm compressor
32.
Feedline
–
In a radio antenna, the feed line is the cable or other transmission line that connects the antenna with the radio transmitter or receiver. In a transmitting antenna, it feeds the radio frequency current from the transmitter to the antenna, in a receiving antenna it transfers the tiny RF voltage induced in the antenna by the radio wave to the receiver. In order to carry RF current efficiently, feed lines are made of specialized types of cable called transmission line, the most widely used types of feed line are coaxial cable, twin-lead, ladder line, and at microwave frequencies, waveguide. Particularly with an antenna, the feed line is a critical component that must be adjusted to work correctly with the antenna. Each type of line has a specific characteristic impedance. This must be matched to the impedance of the antenna and the transmitter and this adjustment is done with a device called an antenna tuner in the transmitter, and sometimes a matching network at the antenna. The degree of mismatch between the feedline and the antenna is measured by an instrument called an SWR meter, which measures the standing wave ratio on the line. It consists of two wire conductors running parallel to each other with a constant spacing, molded in polyethylene insulating material in a flat ribbon-like cable. The distance between the two wires is small relative to the wavelength of the RF signal carried on the wire, furthermore, the RF current in one wire is equal in magnitude and opposite in direction to the RF current on the other wire. Thus, if both wires radiate energy equally, the radiated energies will cancel each other out and there will be near zero radiation at any distance from the wire, twin lead is also immune to external noise or RF energies. Any unwanted external noise or unwanted RF energy induced on the wire from external energy sources will be induced in both wires at the time and equally in magnitude and direction. At the end of the line the inverted signal wire is restored to normal. Any noise will now be equal in magnitude and opposite in direction, twin lead is considered a Balanced line. Coaxial cable is probably the most widely used type of feedline and it consists of a wire center conductor and a braided or solid metallic shield conductor, usually copper or aluminum surrounding it. The center conductor is separated from the shield by a dielectric, usually plastic foam. The shield is covered with an outer plastic insulation jacket, coaxial cables advantage is that the enclosing shield conductor isolates the cable from external electromagnetic fields, so it is very immune to interference. Coaxial cable is considered an unbalanced line, waveguide is used at microwave frequencies, at which other types of feedline have excessive power losses. A waveguide is a metallic conductor or pipe
Feedline
–
Coaxial cable feedline emerging from a VHF ground plane antenna.
33.
Transmitter
–
In electronics and telecommunications a transmitter or radio transmitter is an electronic device which generates a radio frequency alternating current. When a connected antenna is excited by this current, the antenna emits radio waves. The term transmitter is usually limited to equipment that generates radio waves for communication purposes, or radiolocation, such as radar and navigational transmitters. Generators of radio waves for heating or industrial purposes, such as ovens or diathermy equipment, are not usually called transmitters even though they often have similar circuits. The term is used more specifically to refer to a broadcast transmitter. This usage typically includes both the proper, the antenna, and often the building it is housed in. A transmitter can be a piece of electronic equipment, or an electrical circuit within another electronic device. A transmitter and a receiver combined in one unit is called a transceiver, the term transmitter is often abbreviated XMTR or TX in technical documents. The purpose of most transmitters is radio communication of information over a distance, the transmitter combines the information signal to be carried with the radio frequency signal which generates the radio waves, which is called the carrier signal. The information can be added to the carrier in several different ways, in an amplitude modulation transmitter, the information is added to the radio signal by varying its amplitude. In a frequency modulation transmitter, it is added by varying the signals frequency slightly. Many other types of modulation are used, the radio signal from the transmitter is applied to the antenna, which radiates the energy as radio waves. The antenna may be enclosed inside the case or attached to the outside of the transmitter, as in portable devices such as phones, walkie-talkies. In more powerful transmitters, the antenna may be located on top of a building or on a tower, and connected to the transmitter by a feed line. The first primitive radio transmitters were built by German physicist Heinrich Hertz in 1887 during his investigations of radio waves. These generated radio waves by a high voltage spark between two conductors, beginning in 1895 Guglielmo Marconi developed the first practical radio communication systems using spark transmitters. These spark-gap transmitters were used during the first three decades of radio, called the wireless telegraphy or spark era, vacuum tube transmitters took over because they were inexpensive and produced continuous waves, which could be modulated to transmit audio using amplitude modulation. This made possible commercial AM radio broadcasting, which began in about 1920, experimental television transmission had been conducted by radio stations since the late 1920s, but practical television broadcasting didnt begin until the 1940s
Transmitter
–
Continental 816R-5B 35 kW FM transmitter, belonging to American FM radio station KWNR broadcasting on 95.5 MHz in Las Vegas
Transmitter
–
Commercial
FM broadcasting transmitter at radio station
WDET-FM, Wayne State University, Detroit, USA. It broadcasts at 101.9
MHz with a radiated power of 48
kW.
Transmitter
–
Modern
amateur radio transceiver, the ICOM IC-746PRO. It can transmit on the amateur bands from 1.8 MHz to 144 MHz with an output power of 100 W
Transmitter
–
A
CB radio transceiver, a
two way radio transmitting on 27 MHz with a power of 4 W, that can be operated without a license
34.
Antenna (radio)
–
In radio and electronics, an antenna, or aerial, is an electrical device which converts electric power into radio waves, and vice versa. It is usually used with a transmitter or radio receiver. In reception, an antenna intercepts some of the power of a wave in order to produce a tiny voltage at its terminals. Antennas are essential components of all equipment that uses radio, typically an antenna consists of an arrangement of metallic conductors, electrically connected to the receiver or transmitter. These time-varying fields radiate away from the antenna into space as a transverse electromagnetic field wave. Antennas can be designed to transmit and receive radio waves in all directions equally. The first antennas were built in 1888 by German physicist Heinrich Hertz in his experiments to prove the existence of electromagnetic waves predicted by the theory of James Clerk Maxwell. Hertz placed dipole antennas at the point of parabolic reflectors for both transmitting and receiving. He published his work in Annalen der Physik und Chemie, the words antenna and aerial are used interchangeably. Occasionally the term aerial is used to mean a wire antenna, however, note the important international technical journal, the IEEE Transactions on Antennas and Propagation. In the United Kingdom and other areas where British English is used, the origin of the word antenna relative to wireless apparatus is attributed to Italian radio pioneer Guglielmo Marconi. In the summer of 1895, Marconi began testing his wireless system outdoors on his fathers estate near Bologna, Marconi discovered that by raising the aerial wire above the ground and connecting the other side of his transmitter to ground, the transmission range was increased. Soon he was able to transmit signals over a hill, a distance of approximately 2.4 kilometres, in Italian a tent pole is known as lantenna centrale, and the pole with the wire was simply called lantenna. Until then wireless radiating transmitting and receiving elements were simply as aerials or terminals. Because of his prominence, Marconis use of the word spread among wireless researchers. In common usage, the antenna may refer broadly to an entire assembly including support structure, enclosure. Especially at microwave frequencies, an antenna may include not only the actual electrical antenna. An antenna, in converting radio waves to electrical signals or vice versa, is a form of transducer, Antennas are required by any radio receiver or transmitter to couple its electrical connection to the electromagnetic field
Antenna (radio)
Antenna (radio)
–
Antennas of the
Atacama Large Millimeter submillimeter Array.
Antenna (radio)
–
Whip antenna on car, common example of an omnidirectional antenna
35.
Dielectric
–
A dielectric material is an electrical insulator that can be polarized by an applied electric field. Because of dielectric polarization, positive charges are displaced toward the field and this creates an internal electric field that reduces the overall field within the dielectric itself. If a dielectric is composed of weakly bonded molecules, those molecules not only become polarized, the study of dielectric properties concerns storage and dissipation of electric and magnetic energy in materials. Dielectrics are important for explaining various phenomena in electronics, optics, solid-state physics, while the term insulator implies low electrical conduction, dielectric typically means materials with a high polarizability. The latter is expressed by a called the relative permittivity. The term insulator is generally used to indicate electrical obstruction while the term dielectric is used to indicate the energy storing capacity of the material, a common example of a dielectric is the electrically insulating material between the metallic plates of a capacitor. The polarization of the dielectric by the electric field increases the capacitors surface charge for the given electric field strength. The term dielectric was coined by William Whewell in response to a request from Michael Faraday, a perfect dielectric is a material with zero electrical conductivity, thus exhibiting only a displacement current, therefore it stores and returns electrical energy as if it were an ideal capacitor. The electric susceptibility χe of a material is a measure of how easily it polarizes in response to an electric field. This, in turn, determines the electric permittivity of the material and thus many other phenomena in that medium. The susceptibility of a medium is related to its relative permittivity εr by χ e = ε r −1, so in the case of a vacuum, χ e =0. The electric displacement D is related to the polarization density P by D = ε0 E + P = ε0 E = ε r ε0 E, in general, a material cannot polarize instantaneously in response to an applied field. The more general formulation as a function of time is P = ε0 ∫ − ∞ t χ e E d t ′ and that is, the polarization is a convolution of the electric field at previous times with time-dependent susceptibility given by χe. The upper limit of this integral can be extended to infinity as well if one defines χe =0 for Δt <0, an instantaneous response corresponds to Dirac delta function susceptibility χe = χeδ. It is more convenient in a system to take the Fourier transform. Due to the theorem, the integral becomes a simple product. Note the simple frequency dependence of the susceptibility, or equivalently the permittivity, the shape of the susceptibility with respect to frequency characterizes the dispersion properties of the material. In the classical approach to the model, a material is made up of atoms
Dielectric
–
A polarized dielectric material
36.
Radio masts and towers
–
Radio masts and towers are, typically, tall structures designed to support antennas for telecommunications and broadcasting, including television. There are two types, guyed and self supporting structures. They are among the tallest man-made structures, masts are often named after the broadcasting organizations that originally built them or currently use them. In the case of a mast radiator or radiating tower, the whole mast or tower is itself the transmitting antenna, the terms mast and tower are often used interchangeably. However, in engineering terms, a tower is a self-supporting or cantilevered structure. Broadcast engineers in the UK use the same terminology, in US broadcast engineering, a tower is an antenna structure attached to the ground, whereas a mast is a vertical antenna support mounted on some other structure. Masts tend to be cheaper to build but require an extended area surrounding them to accommodate the guy wires, Towers are more commonly used in cities where land is in short supply. There are a few designs that are partly free-standing and partly guyed, called additionally guyed towers. For example, The Gerbrandy tower consists of a tower with a guyed mast on top. The few remaining Blaw-Knox towers do the opposite, they have a lower section surmounted by a freestanding part. Until August 8,1991, the Warsaw radio mast was the worlds tallest supported structure on land, there are over 50 radio structures in the United States that are 600 m or taller. The steel lattice is the most widespread form of construction and it provides great strength, low weight and wind resistance, and economy in the use of materials. Lattices of triangular cross-section are most common, and square lattices are also widely used, guyed masts are often used, the supporting guy lines carry lateral forces such as wind loads, allowing the mast to be very narrow and simply constructed. When built as a tower, the structure may be parallel-sided or taper over part or all of its height, when constructed of several sections which taper exponentially with height, in the manner of the Eiffel Tower, the tower is said to be an Eiffelized one. The Crystal Palace tower in London is an example, guyed masts are sometimes also constructed out of steel tubes. This construction type has the advantage that cables and other components can be protected from weather inside the tube and these masts are mainly used for FM-/TV-broadcasting, but sometimes also as mast radiator. The big mast of Mühlacker transmitting station is an example of this. A disadvantage of this mast type is that it is more affected by winds than masts with open bodies
Radio masts and towers
–
Masts of the
Rugby VLF transmitter in
England
Radio masts and towers
–
The
Tokyo Skytree in 2012, the tallest tower in the world
Radio masts and towers
–
A radio mast base showing how virtually all lateral support is provided by the guy-wires
37.
Moisture
–
Moisture refers to the presence of a liquid, especially water, often in trace amounts. Small amounts of water may be found, for example, in the air, in foods, moisture also refers to the amount of water vapour present in the air. Control of moisture in products can be a part of the process of the product. There is an amount of moisture in what seems to be dry matter. Ranging in products from cornflake cereals to washing powders, moisture can play an important role in the quality of the product. There are two aspects of concern in moisture control in products, allowing too much moisture or too little of it. Water content of foods is also manipulated to reduce the number of calories. Moisture has different effects on different products, influencing the quality of the product. Wood pellets, for instance, are made by taking remainders of wood and grinding them to make compact pellets and they need to have a relatively low water content for combustion efficiency. The more moisture that is allowed in the pellet, the smoke that will be released when the pellet is burned. The need to water content of products has given rise to a new area of science. There are many ways to measure moisture in products, such as different wave measurement, electromagnetic fields, capacitive methods, damp Liquid Dry matter Meteorology EMF measurements Microbiology Water content Electromagnetic Mixing Theory
Moisture
–
Dew on a spider web
38.
Condense
–
Condensation is the change of the physical state of matter from gas phase into liquid phase, and is the reverse of evaporation. The word most often refers to the water cycle and it can also be defined as the change in the state of water vapour to liquid water when in contact with a liquid or solid surface or cloud condensation nuclei within the atmosphere. When the transition happens from the phase into the solid phase directly. A few distinct reversibility scenarios emerge here with respect to the nature of the surface, absorption into the surface of a liquid —is reversible as evaporation. Adsorption onto solid surface at pressures and temperatures higher than the species triple point—also reversible as evaporation, adsorption onto solid surface at pressures and temperatures lower than the species triple point—is reversible as sublimation. Condensation commonly occurs when a vapor is cooled and/or compressed to its limit when the molecular density in the gas phase reaches its maximal threshold. Vapor cooling and compressing equipment that collects condensed liquids is called a condenser, psychrometry measures the rates of condensation through evaporation into the air moisture at various atmospheric pressures and temperatures. Water is the product of its vapor condensation—condensation is the process of such phase conversion, condensation is a crucial component of distillation, an important laboratory and industrial chemistry application. Because condensation is a naturally occurring phenomenon, it can often be used to water in large quantities for human use. Many structures are made solely for the purpose of collecting water from condensation, such as air wells and it is also a crucial process in forming particle tracks in a cloud chamber. In this case, ions produced by an incident particle act as centers for the condensation of the vapor producing the visible cloud trails. Furthermore, condensation is a step in many industrial processes, such as power generation, water desalination, thermal management, refrigeration. Numerous living beings use water made accessible by condensation, a few examples of these are the Australian Thorny Devil, the darkling beetles of the Namibian coast, and the Coast Redwoods of the West Coast of the United States. To alleviate these issues, the air humidity needs to be lowered. This can be done in a number of ways, for example opening windows, turning on extractor fans, using dehumidifiers, drying clothes outside and covering pots and pans whilst cooking. Air conditioning or ventilation systems can be installed that help remove moisture from the air, the amount of water vapour that can be stored in the air can be increased simply by increasing the temperature. However, this can be a double edged sword as most condensation in the home occurs when warm, as the air is cooled, it can no longer hold as much water vapour. This leads to deposition of water on the cool surface and this is very apparent when central heating is used in combination with single glazed windows in winter
Condense
–
Condensation forming in the low pressure zone above the wing of an aircraft due to
adiabatic expansion
Condense
–
Condensation on a window during a rain shower.
39.
Nitrogen
–
Nitrogen is a chemical element with symbol N and atomic number 7. It was first discovered and isolated by Scottish physician Daniel Rutherford in 1772, although Carl Wilhelm Scheele and Henry Cavendish had independently done so at about the same time, Rutherford is generally accorded the credit because his work was published first. Nitrogen is the lightest member of group 15 of the periodic table, the name comes from the Greek πνίγειν to choke, directly referencing nitrogens asphyxiating properties. It is an element in the universe, estimated at about seventh in total abundance in the Milky Way. At standard temperature and pressure, two atoms of the element bind to form dinitrogen, a colourless and odorless diatomic gas with the formula N2, dinitrogen forms about 78% of Earths atmosphere, making it the most abundant uncombined element. Nitrogen occurs in all organisms, primarily in amino acids, in the nucleic acids, the human body contains about 3% nitrogen by mass, the fourth most abundant element in the body after oxygen, carbon, and hydrogen. The nitrogen cycle describes movement of the element from the air, into the biosphere and organic compounds, many industrially important compounds, such as ammonia, nitric acid, organic nitrates, and cyanides, contain nitrogen. The extremely strong bond in elemental nitrogen, the second strongest bond in any diatomic molecule. Synthetically produced ammonia and nitrates are key industrial fertilisers, and fertiliser nitrates are key pollutants in the eutrophication of water systems. Apart from its use in fertilisers and energy-stores, nitrogen is a constituent of organic compounds as diverse as Kevlar used in high-strength fabric, Nitrogen is a constituent of every major pharmacological drug class, including antibiotics. Many notable nitrogen-containing drugs, such as the caffeine and morphine or the synthetic amphetamines. Nitrogen compounds have a long history, ammonium chloride having been known to Herodotus. They were well known by the Middle Ages, alchemists knew nitric acid as aqua fortis, as well as other nitrogen compounds such as ammonium salts and nitrate salts. The mixture of nitric and hydrochloric acids was known as aqua regia, celebrated for its ability to dissolve gold, the discovery of nitrogen is attributed to the Scottish physician Daniel Rutherford in 1772, who called it noxious air. Though he did not recognise it as a different chemical substance, he clearly distinguished it from Joseph Blacks fixed air. The fact that there was a component of air that does not support combustion was clear to Rutherford, Nitrogen was also studied at about the same time by Carl Wilhelm Scheele, Henry Cavendish, and Joseph Priestley, who referred to it as burnt air or phlogisticated air. Nitrogen gas was inert enough that Antoine Lavoisier referred to it as air or azote, from the Greek word άζωτικός. In an atmosphere of nitrogen, animals died and flames were extinguished
Nitrogen
–
Liquid nitrogen
Nitrogen
–
Spectral lines of nitrogen
Nitrogen
–
Nitrogen discharge (spectrum) tube
Nitrogen
–
Table tennis ball made from nitrocellulose.
40.
Gas
–
Gas is one of the four fundamental states of matter. A pure gas may be made up of atoms, elemental molecules made from one type of atom. A gas mixture would contain a variety of pure gases much like the air, what distinguishes a gas from liquids and solids is the vast separation of the individual gas particles. This separation usually makes a colorless gas invisible to the human observer, the interaction of gas particles in the presence of electric and gravitational fields are considered negligible as indicated by the constant velocity vectors in the image. One type of commonly known gas is steam, the gaseous state of matter is found between the liquid and plasma states, the latter of which provides the upper temperature boundary for gases. Bounding the lower end of the temperature scale lie degenerative quantum gases which are gaining increasing attention, high-density atomic gases super cooled to incredibly low temperatures are classified by their statistical behavior as either a Bose gas or a Fermi gas. For a comprehensive listing of these states of matter see list of states of matter. The only chemical elements which are stable multi atom homonuclear molecules at temperature and pressure, are hydrogen, nitrogen and oxygen. These gases, when grouped together with the noble gases. Alternatively they are known as molecular gases to distinguish them from molecules that are also chemical compounds. The word gas is a neologism first used by the early 17th-century Flemish chemist J. B. van Helmont, according to Paracelsuss terminology, chaos meant something like ultra-rarefied water. An alternative story is that Van Helmonts word is corrupted from gahst and these four characteristics were repeatedly observed by scientists such as Robert Boyle, Jacques Charles, John Dalton, Joseph Gay-Lussac and Amedeo Avogadro for a variety of gases in various settings. Their detailed studies ultimately led to a relationship among these properties expressed by the ideal gas law. Gas particles are separated from one another, and consequently have weaker intermolecular bonds than liquids or solids. These intermolecular forces result from interactions between gas particles. Like-charged areas of different gas particles repel, while oppositely charged regions of different gas particles attract one another, transient, randomly induced charges exist across non-polar covalent bonds of molecules and electrostatic interactions caused by them are referred to as Van der Waals forces. The interaction of these forces varies within a substance which determines many of the physical properties unique to each gas. A comparison of boiling points for compounds formed by ionic and covalent bonds leads us to this conclusion, the drifting smoke particles in the image provides some insight into low pressure gas behavior
Gas
–
Drifting
smoke particles provide clues to the movement of the surrounding gas.
Gas
–
Gas phase particles (
atoms,
molecules, or
ions) move around freely in the absence of an applied
electric field.
Gas
–
Shuttle imagery of re-entry phase.
Gas
–
21 April 1990 eruption of
Mount Redoubt,
Alaska, illustrating real gases not in thermodynamic equilibrium.
41.
Pressure
–
Pressure is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure is the relative to the ambient pressure. Various units are used to express pressure, Pressure may also be expressed in terms of standard atmospheric pressure, the atmosphere is equal to this pressure and the torr is defined as 1⁄760 of this. Manometric units such as the centimetre of water, millimetre of mercury, Pressure is the amount of force acting per unit area. The symbol for it is p or P, the IUPAC recommendation for pressure is a lower-case p. However, upper-case P is widely used. The usage of P vs p depends upon the field in one is working, on the nearby presence of other symbols for quantities such as power and momentum. Mathematically, p = F A where, p is the pressure, F is the normal force and it relates the vector surface element with the normal force acting on it. It is incorrect to say the pressure is directed in such or such direction, the pressure, as a scalar, has no direction. The force given by the relationship to the quantity has a direction. If we change the orientation of the element, the direction of the normal force changes accordingly. Pressure is distributed to solid boundaries or across arbitrary sections of normal to these boundaries or sections at every point. It is a parameter in thermodynamics, and it is conjugate to volume. The SI unit for pressure is the pascal, equal to one newton per square metre and this name for the unit was added in 1971, before that, pressure in SI was expressed simply in newtons per square metre. Other units of pressure, such as pounds per square inch, the CGS unit of pressure is the barye, equal to 1 dyn·cm−2 or 0.1 Pa. Pressure is sometimes expressed in grams-force or kilograms-force per square centimetre, but using the names kilogram, gram, kilogram-force, or gram-force as units of force is expressly forbidden in SI. The technical atmosphere is 1 kgf/cm2, since a system under pressure has potential to perform work on its surroundings, pressure is a measure of potential energy stored per unit volume. It is therefore related to density and may be expressed in units such as joules per cubic metre. Similar pressures are given in kilopascals in most other fields, where the prefix is rarely used
Pressure
–
Mercury column
Pressure
–
Pressure as exerted by particle collisions inside a closed container.
Pressure
–
The effects of an external pressure of 700bar on an aluminum cylinder with 5mm wall thickness
Pressure
–
low pressure chamber in
Bundesleistungszentrum Kienbaum, Germany
42.
Water
–
Water is a transparent and nearly colorless chemical substance that is the main constituent of Earths streams, lakes, and oceans, and the fluids of most living organisms. Its chemical formula is H2O, meaning that its molecule contains one oxygen, Water strictly refers to the liquid state of that substance, that prevails at standard ambient temperature and pressure, but it often refers also to its solid state or its gaseous state. It also occurs in nature as snow, glaciers, ice packs and icebergs, clouds, fog, dew, aquifers, Water covers 71% of the Earths surface. It is vital for all forms of life. Only 2. 5% of this water is freshwater, and 98. 8% of that water is in ice and groundwater. Less than 0. 3% of all freshwater is in rivers, lakes, and the atmosphere, a greater quantity of water is found in the earths interior. Water on Earth moves continually through the cycle of evaporation and transpiration, condensation, precipitation. Evaporation and transpiration contribute to the precipitation over land, large amounts of water are also chemically combined or adsorbed in hydrated minerals. Safe drinking water is essential to humans and other even though it provides no calories or organic nutrients. There is a correlation between access to safe water and gross domestic product per capita. However, some observers have estimated that by 2025 more than half of the population will be facing water-based vulnerability. A report, issued in November 2009, suggests that by 2030, in developing regions of the world. Water plays an important role in the world economy, approximately 70% of the freshwater used by humans goes to agriculture. Fishing in salt and fresh water bodies is a source of food for many parts of the world. Much of long-distance trade of commodities and manufactured products is transported by boats through seas, rivers, lakes, large quantities of water, ice, and steam are used for cooling and heating, in industry and homes. Water is an excellent solvent for a variety of chemical substances, as such it is widely used in industrial processes. Water is also central to many sports and other forms of entertainment, such as swimming, pleasure boating, boat racing, surfing, sport fishing, Water is a liquid at the temperatures and pressures that are most adequate for life. Specifically, at atmospheric pressure of 1 bar, water is a liquid between the temperatures of 273.15 K and 373.15 K
Water
–
Water in three states: liquid, solid (
ice), and gas (invisible
water vapor in the air).
Clouds are accumulations of water droplets,
condensed from vapor-saturated air.
Water
–
Impact from a water drop causes an upward "rebound" jet surrounded by circular
capillary waves.
Water
–
Snowflakes by
Wilson Bentley, 1902.
Water
–
Dew drops adhering to a
spider web.
43.
Hygroscopy
–
Hygroscopy is the phenomenon of attracting and holding water molecules from the surrounding environment, which is usually at normal or room temperature. This is achieved through either absorption or adsorption with the absorbing or adsorbing substance becoming physically changed somewhat. Zinc chloride and calcium chloride, as well as potassium hydroxide and sodium hydroxide, are so hygroscopic that they readily dissolve in the water they absorb, not only is sulfuric acid hygroscopic in concentrated form but its solutions are hygroscopic down to concentrations of 10 Vol-% or below. A hygroscopic material will tend to damp and cakey when exposed to moist air. Because of their affinity for moisture, hygroscopic materials might require storage in sealed containers. When added to foods or other materials for the purpose of maintaining moisture content. Materials and compounds exhibit different hygroscopic properties, and this difference can lead to detrimental effects, differences in hygroscopy can be observed in plastic-laminated paperback book covers—often, in a suddenly moist environment, the book cover will curl away from the rest of the book. The unlaminated side of the cover absorbs more moisture than the side and increases in area. This is similar to the function of a thermostats bi-metallic strip, inexpensive dial-type hygrometers make use of this principle using a coiled strip. Deliquescence, the process by which a substance absorbs moisture from the atmosphere until it dissolves in the absorbed water, deliquescence occurs when the vapour pressure of the solution that is formed is less than the partial pressure of water vapour in the air. While some similar forces are at work here, it is different from capillary attraction, a process where glass or other solid substances attract water, the similar-sounding but unrelated word hydroscopic is sometimes used in error for hygroscopic. A hydroscope is a device used for making observations deep under water. The amount of moisture held by hygroscopic materials is proportional to the relative humidity. Tables containing this information can be found in engineering handbooks and is also available from suppliers of various materials and chemicals. Hygroscopy also plays an important role in the engineering of plastic materials, some plastics are hygroscopic while others are not. The seeds of grasses have hygroscopic extensions that bend with changes in humidity. An example is Needle-and-Thread, Hesperostipa comata, each seed has an awn that twists several turns when the seed is released. Increased moisture causes it to untwist, and, upon drying, to twist again, thorny dragons collect moisture in the dry desert via nighttime condensation of dew that forms on their skin and is channeled to their mouths in hygroscopic grooves between the spines of their skin
Hygroscopy
–
Apparatus for the determination of the hygroscopicity of fertilizer, Fixed Nitrogen Research Laboratory, ca.1930
Hygroscopy
–
The
thorny dragon features hygroscopic grooves between the spines of its skin to capture water in its desert habitat.
44.
Mummy
–
Some authorities restrict the use of the term to bodies deliberately embalmed with chemicals, but the use of the word to cover accidentally desiccated bodies goes back to at least 1615 CE. Mummies of humans and other animals have found on every continent. Over one million animal mummies have been found in Egypt, many of which are cats, in addition to the well-known mummies of ancient Egypt, deliberate mummification was a feature of several ancient cultures in areas of America and Asia with very dry climates. The Spirit Cave mummies of Fallon, Nevada in North America were accurately dated at more than 9,400 years old. Before this discovery, the oldest known deliberate mummy was a child, one of the Chinchorro mummies found in the Camarones Valley, Chile, which dates around 5050 BCE. The oldest known naturally mummified corpse is a severed head dated as 6,000 years old. These substances were defined as mummia, the OED defines a mummy as the body of a human being or animal embalmed as a preparation for burial, citing sources from 1615 CE onward. However, Chambers Cyclopædia and the Victorian zoologist Francis Trevelyan Buckland define a mummy as follows, also applied to the frozen carcase of an animal imbedded in prehistoric snow. Wasps of the genus Aleiodes are known as mummy wasps because they wrap their prey as mummies. While interest in the study of mummies dates as far back as Ptolemaic Greece, prior to this, many rediscovered mummies were sold as curiosities or for use in pseudoscientific novelties such as mummia. The first modern scientific examinations of mummies began in 1901, conducted by professors at the English-language Government School of Medicine in Cairo, Egypt. The first X-ray of a mummy came in 1903, when professors Grafton Elliot Smith, British chemist Alfred Lucas applied chemical analyses to Egyptian mummies during this same period, which returned many results about the types of substances used in embalming. Lucas also made significant contributions to the analysis of Tutankhamun in 1922, pathological study of mummies saw varying levels of popularity throughout the 20th century. In 1992, the First World Congress on Mummy Studies was held in Puerto de la Cruz on Tenerife in the Canary Islands, more than 300 scientists attended the Congress to share nearly 100 years of collected data on mummies. This was not possible prior to the Congress due to the unique, in more recent years, CT scanning has become an invaluable tool in the study of mummification by allowing researchers to digitally unwrap mummies without risking damage to the body. The level of detail in such scans is so intricate that small linens used in areas such as the nostrils can be digitally reconstructed in 3-D. Such modelling has been utilized to perform autopsies on mummies to determine cause of death and lifestyle. Mummies are typically divided into one of two categories, anthropogenic or spontaneous
Mummy
–
Howard Carter opens the innermost shrine of King Tutankhamen's tomb near Luxor, Egypt.
Mummy
–
Tori Randall prepares a 550-year-old Peruvian child mummy for a CT scan at Naval Medical Center San Diego.
Mummy
–
Mummy in the British Museum
Mummy
–
Painted mummy bandage
45.
PubMed Identifier
–
PubMed is a free search engine accessing primarily the MEDLINE database of references and abstracts on life sciences and biomedical topics. The United States National Library of Medicine at the National Institutes of Health maintains the database as part of the Entrez system of information retrieval, from 1971 to 1997, MEDLINE online access to the MEDLARS Online computerized database primarily had been through institutional facilities, such as university libraries. PubMed, first released in January 1996, ushered in the era of private, free, home-, the PubMed system was offered free to the public in June 1997, when MEDLINE searches via the Web were demonstrated, in a ceremony, by Vice President Al Gore. Information about the journals indexed in MEDLINE, and available through PubMed, is found in the NLM Catalog. As of 5 January 2017, PubMed has more than 26.8 million records going back to 1966, selectively to the year 1865, and very selectively to 1809, about 500,000 new records are added each year. As of the date,13.1 million of PubMeds records are listed with their abstracts. In 2016, NLM changed the system so that publishers will be able to directly correct typos. Simple searches on PubMed can be carried out by entering key aspects of a subject into PubMeds search window, when a journal article is indexed, numerous article parameters are extracted and stored as structured information. Such parameters are, Article Type, Secondary identifiers, Language, publication type parameter enables many special features. As these clinical girish can generate small sets of robust studies with considerable precision, since July 2005, the MEDLINE article indexing process extracts important identifiers from the article abstract and puts those in a field called Secondary Identifier. The secondary identifier field is to store numbers to various databases of molecular sequence data, gene expression or chemical compounds. For clinical trials, PubMed extracts trial IDs for the two largest trial registries, ClinicalTrials. gov and the International Standard Randomized Controlled Trial Number Register, a reference which is judged particularly relevant can be marked and related articles can be identified. If relevant, several studies can be selected and related articles to all of them can be generated using the Find related data option, the related articles are then listed in order of relatedness. To create these lists of related articles, PubMed compares words from the title and abstract of each citation, as well as the MeSH headings assigned, using a powerful word-weighted algorithm. The related articles function has been judged to be so precise that some researchers suggest it can be used instead of a full search, a strong feature of PubMed is its ability to automatically link to MeSH terms and subheadings. Examples would be, bad breath links to halitosis, heart attack to myocardial infarction, where appropriate, these MeSH terms are automatically expanded, that is, include more specific terms. Terms like nursing are automatically linked to Nursing or Nursing and this important feature makes PubMed searches automatically more sensitive and avoids false-negative hits by compensating for the diversity of medical terminology. The My NCBI area can be accessed from any computer with web-access, an earlier version of My NCBI was called PubMed Cubby
PubMed Identifier
–
PubMed
46.
National Diet Library
–
The National Diet Library is the only national library in Japan. It was established in 1948 for the purpose of assisting members of the National Diet of Japan in researching matters of public policy, the library is similar in purpose and scope to the United States Library of Congress. The National Diet Library consists of two facilities in Tokyo and Kyoto, and several other branch libraries throughout Japan. The Diets power in prewar Japan was limited, and its need for information was correspondingly small, the original Diet libraries never developed either the collections or the services which might have made them vital adjuncts of genuinely responsible legislative activity. Until Japans defeat, moreover, the executive had controlled all political documents, depriving the people and the Diet of access to vital information. The U. S. occupation forces under General Douglas MacArthur deemed reform of the Diet library system to be an important part of the democratization of Japan after its defeat in World War II. In 1946, each house of the Diet formed its own National Diet Library Standing Committee, hani Gorō, a Marxist historian who had been imprisoned during the war for thought crimes and had been elected to the House of Councillors after the war, spearheaded the reform efforts. Hani envisioned the new body as both a citadel of popular sovereignty, and the means of realizing a peaceful revolution, the National Diet Library opened in June 1948 in the present-day State Guest-House with an initial collection of 100,000 volumes. The first Librarian of the Diet Library was the politician Tokujirō Kanamori, the philosopher Masakazu Nakai served as the first Vice Librarian. In 1949, the NDL merged with the National Library and became the national library in Japan. At this time the collection gained a million volumes previously housed in the former National Library in Ueno. In 1961, the NDL opened at its present location in Nagatachō, in 1986, the NDLs Annex was completed to accommodate a combined total of 12 million books and periodicals. The Kansai-kan, which opened in October 2002 in the Kansai Science City, has a collection of 6 million items, in May 2002, the NDL opened a new branch, the International Library of Childrens Literature, in the former building of the Imperial Library in Ueno. This branch contains some 400,000 items of literature from around the world. Though the NDLs original mandate was to be a library for the National Diet. In the fiscal year ending March 2004, for example, the library reported more than 250,000 reference inquiries, in contrast, as Japans national library, the NDL collects copies of all publications published in Japan. The NDL has an extensive collection of some 30 million pages of documents relating to the Occupation of Japan after World War II. This collection include the documents prepared by General Headquarters and the Supreme Commander of the Allied Powers, the Far Eastern Commission, the NDL maintains a collection of some 530,000 books and booklets and 2 million microform titles relating to the sciences
National Diet Library
–
Tokyo Main Library of the National Diet Library
National Diet Library
–
Kansai-kan of the National Diet Library
National Diet Library
–
The National Diet Library
National Diet Library
–
Main building in Tokyo
. PMID 8550493.
