1.
Density
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The density, or more precisely, the volumetric mass density, of a substance is its mass per unit volume. The symbol most often used for density is ρ, although the Latin letter D can also be used. Mathematically, density is defined as mass divided by volume, ρ = m V, where ρ is the density, m is the mass, and V is the volume. In some cases, density is defined as its weight per unit volume. For a pure substance the density has the numerical value as its mass concentration. Different materials usually have different densities, and density may be relevant to buoyancy, purity, osmium and iridium are the densest known elements at standard conditions for temperature and pressure but certain chemical compounds may be denser. Thus a relative density less than one means that the floats in water. The density of a material varies with temperature and pressure and this variation is typically small for solids and liquids but much greater for gases. Increasing the pressure on an object decreases the volume of the object, increasing the temperature of a substance decreases its density by increasing its volume. In most materials, heating the bottom of a results in convection of the heat from the bottom to the top. This causes it to rise relative to more dense unheated material, the reciprocal of the density of a substance is occasionally called its specific volume, a term sometimes used in thermodynamics. Density is a property in that increasing the amount of a substance does not increase its density. Archimedes knew that the irregularly shaped wreath could be crushed into a cube whose volume could be calculated easily and compared with the mass, upon this discovery, he leapt from his bath and ran naked through the streets shouting, Eureka. As a result, the term eureka entered common parlance and is used today to indicate a moment of enlightenment, the story first appeared in written form in Vitruvius books of architecture, two centuries after it supposedly took place. Some scholars have doubted the accuracy of this tale, saying among other things that the method would have required precise measurements that would have been difficult to make at the time, from the equation for density, mass density has units of mass divided by volume. As there are units of mass and volume covering many different magnitudes there are a large number of units for mass density in use. The SI unit of kilogram per metre and the cgs unit of gram per cubic centimetre are probably the most commonly used units for density.1,000 kg/m3 equals 1 g/cm3. In industry, other larger or smaller units of mass and or volume are often more practical, see below for a list of some of the most common units of density
2.
Electrical resistivity and conductivity
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Electrical resistivity is an intrinsic property that quantifies how strongly a given material opposes the flow of electric current. A low resistivity indicates a material that allows the flow of electric current. Resistivity is commonly represented by the Greek letter ρ, the SI unit of electrical resistivity is the ohm-metre. Electrical conductivity or specific conductance is the reciprocal of electrical resistivity and it is commonly represented by the Greek letter σ, but κ or γ are also occasionally used. Its SI unit is siemens per metre and CGSE unit is reciprocal second, many resistors and conductors have a uniform cross section with a uniform flow of electric current, and are made of one material. All copper wires, irrespective of their shape and size, have approximately the same resistivity, every material has its own characteristic resistivity – for example, resistivity of rubber is far larger than coppers. If the pipes are the size and shape, the pipe full of sand has higher resistance to flow. Resistance, however, is not solely determined by the presence or absence of sand and it also depends on the length and width of the pipe, short or wide pipes have lower resistance than narrow or long pipes. The above equation can be transposed to get Pouillets law, R = ρ ℓ A, the resistance of a given material increases with length, but decreases with increasing cross-sectional area. From the above equations, resistivity has the SI unit ohm metre, the formula R = ρ ℓ / A can be used to intuitively understand the meaning of a resistivity value. For example, if A = 7000100000000000000♠1 m2 ℓ = 7000100000000000000♠1 m, Conductivity, σ, is defined as the inverse of resistivity, σ =1 ρ. Conductivity has SI units of siemens per metre, the above definition was specific to resistors or conductors with a uniform cross-section, where current flows uniformly through them. A more basic and general definition starts from the fact that a field inside a material makes electric current flow. Conductivity is the inverse, σ =1 ρ = J E, for example, rubber is a material with large ρ and small σ—because even a very large electric field in rubber makes almost no current flow through it. On the other hand, copper is a material with small ρ, according to elementary quantum mechanics, electrons in an atom do not take on arbitrary energy values. Rather, electrons only occupy discrete energy levels in an atom or crystal. When a large number of such allowed energy levels are spaced close together —i. e. have similar energies— we can talk about these energy levels together as an energy band. There can be many such bands in a material, depending on the atomic number
3.
Siemens (unit)
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The siemens is the unit of electric conductance, electric susceptance and electric admittance in the International System of Units. The 14th General Conference on Weights and Measures approved the addition of the siemens as a unit in 1971. The unit is named after Ernst Werner von Siemens, as with every SI unit whose name is derived from the proper name of a person, the first letter of its symbol is upper case, the lower-case s is the symbol for the second. When an SI unit is spelled out in English, it should begin with a lower-case letter. In English, the same form siemens is used both for the singular and plural, the unit siemens for the conductance G is defined by S = Ω −1 = A V where Ω is the ohm, A is the ampere, and V is the volt. For a device with a conductance of one siemens, the current through the device will increase by one ampere for every increase of one volt of electric potential difference across the device. The conductance of a resistor with a resistance of five ohms, for example, is −1, mho /moʊ/ is an alternative name of the same unit, the reciprocal of one ohm. Mho is derived from spelling ohm backwards and is written with an upside-down capital Greek letter Omega, ℧, according to Maver the term mho was suggested by Sir William Thomson. The mho was officially renamed to the siemens, replacing the old meaning of the siemens unit, the term siemens, as it is an SI term, is used universally in science and often in electrical applications, while mho is still used primarily in electronic applications. Likewise, it is difficult to distinguish the symbol S from the lower-case s where second is meant, brochure The International System of Units issued by the BIPM Different units named after Siemens
4.
Thermal conductivity
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In physics, thermal conductivity is the property of a material to conduct heat. It is evaluated primarily in terms of Fouriers Law for heat conduction, heat transfer occurs at a lower rate across materials of low thermal conductivity than across materials of high thermal conductivity. Correspondingly, materials of high thermal conductivity are used in heat sink applications. The thermal conductivity of a material may depend on temperature, the reciprocal of thermal conductivity is called thermal resistivity. Thermal conductivity is actually a tensor, which means it is possible to have different values in different directions, in SI units, thermal conductivity is measured in watts per meter-kelvin. The dimension of thermal conductivity is M1L1T−3Θ−1 and these variables are mass, length, time, and temperature. In Imperial units, thermal conductivity is measured in BTU/, other units which are closely related to the thermal conductivity are in common use in the construction and textile industries. The construction industry makes use of such as the R-value. Although related to the conductivity of a material used in an insulation product, R-. Likewise the textile industry has several units including the tog and the clo which express thermal resistance of a material in a way analogous to the R-values used in the construction industry, there are a number of ways to measure thermal conductivity. Each of these is suitable for a range of materials, depending on the thermal properties. There is a distinction between steady-state and transient techniques, in general, steady-state techniques are useful when the temperature of the material does not change with time. This makes the signal analysis straightforward, the disadvantage is that a well-engineered experimental setup is usually needed. The Divided Bar is the most common used for consolidated rock solids. Thermal conductivity is important in science, research, electronics, building insulation and related fields. Several materials are shown in the list of thermal conductivities and these should be considered approximate due to the uncertainties related to material definitions. High energy generation rates within electronics or turbines require the use of materials with high thermal conductivity such as copper, aluminium, the reciprocal of thermal conductivity is thermal resistivity, usually expressed in kelvin-meters per watt. For a given thickness of a material, that particular constructions thermal resistance, unfortunately, there are differing definitions for these terms
5.
Kelvin
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The kelvin is a unit of measure for temperature based upon an absolute scale. It is one of the seven units in the International System of Units and is assigned the unit symbol K. The kelvin is defined as the fraction 1⁄273.16 of the temperature of the triple point of water. In other words, it is defined such that the point of water is exactly 273.16 K. The Kelvin scale is named after the Belfast-born, Glasgow University engineer and physicist William Lord Kelvin, unlike the degree Fahrenheit and degree Celsius, the kelvin is not referred to or typeset as a degree. The kelvin is the unit of temperature measurement in the physical sciences, but is often used in conjunction with the Celsius degree. The definition implies that absolute zero is equivalent to −273.15 °C, Kelvin calculated that absolute zero was equivalent to −273 °C on the air thermometers of the time. This absolute scale is known today as the Kelvin thermodynamic temperature scale, when spelled out or spoken, the unit is pluralised using the same grammatical rules as for other SI units such as the volt or ohm. When reference is made to the Kelvin scale, the word kelvin—which is normally a noun—functions adjectivally to modify the noun scale and is capitalized, as with most other SI unit symbols there is a space between the numeric value and the kelvin symbol. Before the 13th CGPM in 1967–1968, the unit kelvin was called a degree and it was distinguished from the other scales with either the adjective suffix Kelvin or with absolute and its symbol was °K. The latter term, which was the official name from 1948 until 1954, was ambiguous since it could also be interpreted as referring to the Rankine scale. Before the 13th CGPM, the form was degrees absolute. The 13th CGPM changed the name to simply kelvin. Its measured value was 7002273160280000000♠0.01028 °C with an uncertainty of 60 µK, the use of SI prefixed forms of the degree Celsius to express a temperature interval has not been widely adopted. In 2005 the CIPM embarked on a program to redefine the kelvin using a more experimentally rigorous methodology, the current definition as of 2016 is unsatisfactory for temperatures below 20 K and above 7003130000000000000♠1300 K. In particular, the committee proposed redefining the kelvin such that Boltzmanns constant takes the exact value 6977138065049999999♠1. 3806505×10−23 J/K, from a scientific point of view, this will link temperature to the rest of SI and result in a stable definition that is independent of any particular substance. From a practical point of view, the redefinition will pass unnoticed, the kelvin is often used in the measure of the colour temperature of light sources. Colour temperature is based upon the principle that a black body radiator emits light whose colour depends on the temperature of the radiator, black bodies with temperatures below about 7003400000000000000♠4000 K appear reddish, whereas those above about 7003750000000000000♠7500 K appear bluish
6.
Melting point
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The melting point of a solid is the temperature at which it changes state from solid to liquid at atmospheric pressure. At the melting point the solid and liquid phase exist in equilibrium, the melting point of a substance depends on pressure and is usually specified at standard pressure. When considered as the temperature of the change from liquid to solid. Because of the ability of some substances to supercool, the point is not considered as a characteristic property of a substance. For most substances, melting and freezing points are approximately equal, for example, the melting point and freezing point of mercury is 234.32 kelvins. However, certain substances possess differing solid-liquid transition temperatures, for example, agar melts at 85 °C and solidifies from 31 °C to 40 °C, such direction dependence is known as hysteresis. The melting point of ice at 1 atmosphere of pressure is close to 0 °C. In the presence of nucleating substances the freezing point of water is the same as the melting point, the chemical element with the highest melting point is tungsten, at 3687 K, this property makes tungsten excellent for use as filaments in light bulbs. Many laboratory techniques exist for the determination of melting points, a Kofler bench is a metal strip with a temperature gradient. Any substance can be placed on a section of the strip revealing its thermal behaviour at the temperature at that point, differential scanning calorimetry gives information on melting point together with its enthalpy of fusion. A basic melting point apparatus for the analysis of crystalline solids consists of an oil bath with a transparent window, the several grains of a solid are placed in a thin glass tube and partially immersed in the oil bath. The oil bath is heated and with the aid of the melting of the individual crystals at a certain temperature can be observed. In large/small devices, the sample is placed in a heating block, the measurement can also be made continuously with an operating process. For instance, oil refineries measure the point of diesel fuel online, meaning that the sample is taken from the process. This allows for more frequent measurements as the sample does not have to be manually collected, for refractory materials the extremely high melting point may be determined by heating the material in a black body furnace and measuring the black-body temperature with an optical pyrometer. For the highest melting materials, this may require extrapolation by several hundred degrees, the spectral radiance from an incandescent body is known to be a function of its temperature. An optical pyrometer matches the radiance of a body under study to the radiance of a source that has been previously calibrated as a function of temperature, in this way, the measurement of the absolute magnitude of the intensity of radiation is unnecessary. However, known temperatures must be used to determine the calibration of the pyrometer, for temperatures above the calibration range of the source, an extrapolation technique must be employed
7.
Celsius
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Celsius, also known as centigrade, is a metric scale and unit of measurement for temperature. As an SI derived unit, it is used by most countries in the world and it is named after the Swedish astronomer Anders Celsius, who developed a similar temperature scale. The degree Celsius can refer to a temperature on the Celsius scale as well as a unit to indicate a temperature interval. Before being renamed to honour Anders Celsius in 1948, the unit was called centigrade, from the Latin centum, which means 100, and gradus, which means steps. The scale is based on 0° for the point of water. This scale is widely taught in schools today, by international agreement the unit degree Celsius and the Celsius scale are currently defined by two different temperatures, absolute zero, and the triple point of VSMOW. This definition also precisely relates the Celsius scale to the Kelvin scale, absolute zero, the lowest temperature possible, is defined as being precisely 0 K and −273.15 °C. The temperature of the point of water is defined as precisely 273.16 K at 611.657 pascals pressure. This definition fixes the magnitude of both the degree Celsius and the kelvin as precisely 1 part in 273.16 of the difference between absolute zero and the point of water. Thus, it sets the magnitude of one degree Celsius and that of one kelvin as exactly the same, additionally, it establishes the difference between the two scales null points as being precisely 273.15 degrees. In his paper Observations of two persistent degrees on a thermometer, he recounted his experiments showing that the point of ice is essentially unaffected by pressure. He also determined with precision how the boiling point of water varied as a function of atmospheric pressure. He proposed that the point of his temperature scale, being the boiling point. This pressure is known as one standard atmosphere, the BIPMs 10th General Conference on Weights and Measures later defined one standard atmosphere to equal precisely 1013250dynes per square centimetre. On 19 May 1743 he published the design of a mercury thermometer, in 1744, coincident with the death of Anders Celsius, the Swedish botanist Carolus Linnaeus reversed Celsiuss scale. In it, Linnaeus recounted the temperatures inside the orangery at the University of Uppsala Botanical Garden, since the 19th century, the scientific and thermometry communities worldwide referred to this scale as the centigrade scale. Temperatures on the scale were often reported simply as degrees or. More properly, what was defined as centigrade then would now be hectograde.2 gradians, for scientific use, Celsius is the term usually used, with centigrade otherwise continuing to be in common but decreasing use, especially in informal contexts in English-speaking countries
8.
Fahrenheit
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Fahrenheit is a temperature scale based on one proposed in 1724 by the physicist Daniel Gabriel Fahrenheit, after whom the scale is named. It uses the degree Fahrenheit as the unit, several accounts of how he originally defined his scale exist. The lower defining point,0 °F, was established as the temperature of a solution of brine made from parts of ice. Further limits were established as the point of ice and his best estimate of the average human body temperature. All other countries in the world now use the Celsius scale, defined since 1954 by absolute zero being −273.15 °C, on the Fahrenheit scale, the freezing point of water is 32 degrees Fahrenheit and the boiling point is 212 °F. This puts the boiling and freezing points of water exactly 180 degrees apart, therefore, a degree on the Fahrenheit scale is 1⁄180 of the interval between the freezing point and the boiling point. On the Celsius scale, the freezing and boiling points of water are 100 degrees apart, a temperature interval of 1 °F is equal to an interval of 5⁄9 degrees Celsius. The Fahrenheit and Celsius scales intersect at −40°, absolute zero is −273.15 °C or −459.67 °F. For an exact conversion, the formulas can be applied. Again, f is the value in Fahrenheit and c the value in Celsius, f °Fahrenheit to c °Celsius, C °Celsius to f °Fahrenheit, −40 = f. Fahrenheit proposed his temperature scale in 1724, basing it on two points of temperature. In his initial scale, the point is determined by placing the thermometer in a mixture of ice, water. This is a mixture which stabilizes its temperature automatically, that stable temperature was defined as 0 °F. The second point,96 degrees, was approximately the human bodys temperature, in any case, the definition of the Fahrenheit scale has changed since. According to a letter Fahrenheit wrote to his friend Herman Boerhaave, his scale was built on the work of Ole Rømer, whom he had met earlier. In Rømers scale, brine freezes at zero, water freezes and melts at 7.5 degrees, body temperature is 22.5, Fahrenheit multiplied each value by four in order to eliminate fractions and increase the granularity of the scale. Fahrenheit observed that water boils at about 212 degrees using this scale, under this system, the Fahrenheit scale is redefined slightly so that the freezing point of water is exactly 32 °F, and the boiling point is exactly 212 °F or 180 degrees higher. It is for this reason that human body temperature is approximately 98° on the revised scale
9.
Aliphatic compound
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In organic chemistry, hydrocarbons are divided into two classes, aromatic compounds and aliphatic compounds also known as non-aromatic compounds. Aliphatics can be cyclic, but only aromatic compounds contain an especially stable ring of atoms, aliphatic compounds can be saturated, like Hexane, or unsaturated, like Hexene and Hexyne. Open-chain compounds contain no rings of any type, and are thus aliphatic, aliphatic compounds can be saturated, joined by single bonds, or unsaturated, with double bonds or triple bonds. Besides hydrogen, other elements can be bound to the chain, the most common being oxygen, nitrogen, sulfur. The least complex aliphatic compound is methane, most aliphatic compounds are flammable, allowing the use of hydrocarbons as fuel, such as methane in Bunsen burners and as liquefied natural gas, and acetylene in welding. The most important aliphatic compounds are, n-, iso- and cyclo-alkanes n-, iso- and cyclo-alkenes and -alkynes
10.
Aromaticity
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Aromatic molecules are very stable, and do not break apart easily to react with other substances. Organic compounds that are not aromatic are classified as aliphatic compounds—they might be cyclic, since the most common aromatic compounds are derivatives of benzene, the word “aromatic” occasionally refers informally to benzene derivatives, and so it was first defined. Nevertheless, many aromatic compounds exist. In living organisms, for example, the most common aromatic rings are the bases in RNA and DNA. An aromatic functional group or other substituent is called an aryl group, the earliest use of the term aromatic was in an article by August Wilhelm Hofmann in 1855. Hofmann used the term for a class of compounds, many of which have odors. In terms of the nature of the molecule, aromaticity describes a conjugated system often made of alternating single and double bonds in a ring. This configuration allows for the electrons in the pi system to be delocalized around the ring, increasing the molecules stability. The molecule cannot be represented by one structure, but rather a hybrid of different structures. These molecules cannot be found in one of these representations, with the longer single bonds in one location. Rather, the molecule exhibits bond lengths in between those of single and double bonds and this commonly seen model of aromatic rings, namely the idea that benzene was formed from a six-membered carbon ring with alternating single and double bonds, was developed by August Kekulé. The model for benzene consists of two forms, which corresponds to the double and single bonds superimposing to produce six one-and-a-half bonds. Benzene is a stable molecule than would be expected without accounting for charge delocalization. As is standard for resonance diagrams, the use of an arrow indicates that two structures are not distinct entities but merely hypothetical possibilities. Neither is a representation of the actual compound, which is best represented by a hybrid of these structures. A C=C bond is shorter than a C−C bond, but benzene is perfectly hexagonal—all six carbon–carbon bonds have the same length, intermediate between that of a single and that of a double bond. In a cyclic molecule with three alternating double bonds, cyclohexatriene, the length of the single bond would be 1.54 Å. However, in a molecule of benzene, the length of each of the bonds is 1.40 Å, a better representation is that of the circular π-bond, in which the electron density is evenly distributed through a π-bond above and below the ring
11.
Polyamide
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A polyamide is a macromolecule with repeating units linked by amide bonds. Polyamides occur both naturally and artificially, examples of naturally occurring polyamides are proteins, such as wool and silk. Artificially made polyamides can be made through step-growth polymerization or solid-phase synthesis yielding materials such as nylons, aramids, synthetic polyamides are commonly used in textiles, automotive applications, carpets and sportswear due to their high durability and strength. The transportation manufacturing industry is the consumer, accounting for 35% of polyamide consumption. Polymers of amino acids are known as polypeptides or proteins, the monomers can be amides themselves, α, ω-amino acids or a stoichiometric mixture of a diamine and a diacid. Both these kinds of precursors give a homopolymer, Polyamides are easily copolymerized, and thus many mixtures of monomers are possible which can in turn lead to many copolymers. Additionally many nylon polymers are miscible with one another allowing the creation of blends, production of polymers requires the repeated joining of two groups to form an amide linkage. In this case this specifically involves amide bonds, and the two involved are an amine group, and a terminal carbonyl component of a functional group. These react to produce a bond, creating a singular amide linkage. This process involves the elimination of other atoms previously part of the functional groups, the carbonyl-component may be part of either a carboxylic acid group or the more reactive acyl halide derivative. The condensation reaction is used to produce nylon polymers in industry. Nylons must specifically include an straight chain monomer, the amide link is produced from an amine group, and a carboxylic acid group. The hydroxyl from the carboxylic acid combines with a hydrogen from the amine, and gives rise to water, as an example of condensation reactions, consider that in living organisms, Amino acids are condensed with one another by an enzyme to form amide linkages. The resulting polyamides are known as proteins or polypeptides, in the diagram below, consider the amino-acids as single aliphatic monomers reacting with identical molecules to form a polyamide, focusing on solely the amine and acid groups. The polymerization reaction with the amine group eliminates hydrogen chloride, the acid chloride route can be used as a laboratory synthesis to avoid heating and obtain an almost instantaneous reaction. The aromatic moiety itself does not participate in reaction, but it does increase the rigidity. In the diagram below, Aramid is made from two different monomers which continuously alternate to form the polymer, Aramid is an aromatic polyamide, Polyamides can also be synthesized from dinitriles using acid catalysis via an application of the Ritter reaction. This method is applicable for preparation of nylon 1,6 from adiponitrile, formaldehyde, additionally, polyamides can be synthesized from glycols and dinitriles using this method as well
12.
Thermoplastic
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A thermoplastic, or thermosoftening plastic, is a plastic material, a polymer, that becomes pliable or moldable above a specific temperature and solidifies upon cooling. Most thermoplastics have a molecular weight. The polymer chains associate through intermolecular forces, which weaken rapidly with increased temperature, thermoplastics differ from thermosetting polymers, which form irreversible chemical bonds during the curing process. Thermosets do not melt, but decompose and do not reform upon cooling, above its glass transition temperature and below its melting point, the physical properties of a thermoplastic change drastically without an associated phase change. Some thermoplastics do not fully crystallize below the transition temperature. Amorphous and semi-amorphous plastics are used when high optical clarity is necessary, amorphous and semi-amorphous plastics are less resistant to chemical attack and environmental stress cracking because they lack a crystalline structure. Brittleness can be decreased with the addition of plasticizers, which increases the mobility of amorphous chain segments to effectively lowers the transition temperature. Modification of the polymer through copolymerization or through the addition of side chains to monomers before polymerization can also lower it. Naval Research Laboratory developed thermoplastic armor, that can be repaired in the field by a user via tools for pressing irons, acrylic, a polymer called poly, is also known by trade names such as Lucite, Perspex and Plexiglas. It serves as a substitute for glass for items such as aquariums, motorcycle helmet visors, aircraft windows, viewing ports of submersibles. It is extensively used to make signs, including lettering and logos, in medicine, it is used in bone cement and to replace eye lenses. Acrylic paint consists of PMMA particles suspended in water, acrylonitrile butadiene styrene is a terpolymer synthesized from styrene and acrylonitrile in the presence of polybutadiene. ABS is a material that exhibits high impact resistance and mechanical toughness. It poses few risks to health under normal handling. It is used in consumer products, such as toys, appliances. Nylon belongs to a class of polymers called polyamides and it has served as a substitute mainly for hemp, cotton and silk, in products such as parachutes, cords, sails, flak vests and womens clothing. Nylon fibers are useful in making fabrics, rope, carpets and musical strings, whereas in bulk form, Nylon is used for mechanical parts including machine screws, gears, in addition, it is used in the manufacture of heat-resistant composite materials. Polylactic acid is a biodegradable thermoplastic aliphatic polyester derived from renewable resources, such as starch, tapioca roots, chips or starch
13.
Thin film
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A thin film is a layer of material ranging from fractions of a nanometer to several micrometers in thickness. The controlled synthesis of materials as thin films is a step in many applications. A familiar example is the mirror, which typically has a thin metal coating on the back of a sheet of glass to form a reflective interface. The process of silvering was once used to produce mirrors. It is also being applied to pharmaceuticals, via thin-film drug delivery, a stack of thin films is called a multilayer. In addition to their applied interest, thin films play an important role in the development and study of materials with new, examples include multiferroic materials, and superlattices that allow the study of quantum confinement by creating two-dimensional electron states. The act of applying a thin film to a surface is thin-film deposition – any technique for depositing a film of material onto a substrate or onto previously deposited layers. Thin is a term, but most deposition techniques control layer thickness within a few tens of nanometres. Molecular beam epitaxy and atomic layer deposition allow a single layer of atoms to be deposited at a time and it is useful in the manufacture of optics, electronics, packaging, and in contemporary art. Deposition techniques fall into two categories, depending on whether the process is primarily chemical or physical. Here, a fluid precursor undergoes a change at a solid surface. An everyday example is the formation of soot on an object when it is placed inside a flame. Chemical deposition is further categorized by the phase of the precursor, Plating relies on liquid precursors, some plating processes are driven entirely by reagents in the solution, but by far the most commercially important process is electroplating. It was not commonly used in processing for many years. Chemical solution deposition or chemical bath deposition uses a liquid precursor and this is a relatively inexpensive, simple thin film process that is able to produce stoichiometrically accurate crystalline phases. This technique is known as the sol-gel method because the sol gradually evolves towards the formation of a gel-like diphasic system. The speed at which the solution is spun and the viscosity of the sol determine the thickness of the deposited film. Repeated depositions can be carried out to increase the thickness of films as desired, thermal treatment is often carried out in order to crystallize the amorphous spin coated film
14.
DuPont
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In the 20th century, DuPont developed many polymers such as Vespel, neoprene, nylon, Corian, Teflon, Mylar, Kapton, Kevlar, Zemdrain, M5 fiber, Nomex, Tyvek, Sorona, Corfam, and Lycra. DuPont developed Freon for the refrigerant industry, and later more environmentally friendly refrigerants and it also developed synthetic pigments and paints including ChromaFlair. In 2014, DuPont was the fourth largest chemical company based on market capitalization. Its stock price is a component of the Dow Jones Industrial Average, DuPont was founded in 1802 by Éleuthère Irénée du Pont, using capital raised in France and gunpowder machinery imported from France. It began as a manufacturer of gunpowder, as du Pont noticed that the industry in North America was lagging behind Europe, the Eleutherian Mills site is now a museum and a National Historic Landmark. DuPont continued to expand, moving into the production of dynamite, in 1902, DuPonts president, Eugene du Pont, died, and the surviving partners sold the company to three great-grandsons of the original founder. Charles Lee Reese was appointed as director and the company began centralizing their research departments, the company subsequently purchased several smaller chemical companies, and in 1912 these actions gave rise to government scrutiny under the Sherman Antitrust Act. The courts declared that the dominance of the explosives business constituted a monopoly. The court ruling resulted in the creation of the Hercules Powder Company, at the time of divestment, DuPont retained the single base nitrocellulose powders, while Hercules held the double base powders combining nitrocellulose and nitroglycerine. DuPont subsequently developed the Improved Military Rifle line of smokeless powders, in 1910, DuPont published a brochure entitled Farming with Dynamite. DuPont also established two of the first industrial laboratories in the United States, where began the work on cellulose chemistry, lacquers. DuPont Central Research was established at the DuPont Experimental Station, across the Brandywine Creek from the powder mills. In 1914, Pierre S. du Pont invested in the automobile industry. The following year he was invited to sit on GMs board of directors, the DuPont company would assist the struggling automobile company further with a $25 million purchase of GM stock. In 1920, Pierre S. du Pont was elected president of General Motors, under du Ponts guidance, GM became the number one automobile company in the world. However, in 1957, because of DuPonts influence within GM, in the 1920s, DuPont continued its emphasis on materials science, hiring Wallace Carothers to work on polymers in 1928. Carothers invented neoprene, a rubber, the first polyester superpolymer. The invention of Teflon followed a few years later, DuPont introduced phenothiazine as an insecticide in 1935
15.
Nylon 66
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Nylon 66 is a type of polyamide or nylon. Nylons come in types, and the two most common for textile and plastics industries are nylon 6 and nylon 6,6. Nylon 6,6 is made of two monomers each containing 6 carbon atoms, hexamethylenediamine and adipic acid, which give nylon 66 or PA66, nylon 66 is synthesised by polycondensation of hexamethylenediamine and adipic acid. Equivalent amounts of hexamethylenediamine and adipic acid are combined with water in a reactor and this is crystallized to make nylon salt, which has precisely stoichiometric equivalents. The nylon salt goes into a vessel where polymerization process takes place either in batches or continuously. N HOOC-4-COOH + n H2N-6-NH2 → n + 2n H2O Removing water drives the reaction toward polymerization through the formation of bonds from the acid. Thus molten nylon 66 is formed and it can either be extruded and granulated at this point or directly spun into fibres by extrusion through a spinneret and cooling to form filaments. In 2011 worldwide production was 2 million tons, at that time fibres consumed just over half of production and engineering resins the rest. It is not used in due to its inability to be oriented. Fibre markets represented 55% of the 2010 demand with engineering thermoplastics being the remainder, nylon 66 is frequently used when high mechanical strength, rigidity, good stability under heat and/or chemical resistance are required It is used in fibers for textiles and carpets and molded parts. For textiles, fibers are sold under various brands, for example Nilit brands or the Cordura brand for luggage, but it is used in airbags, apparel. Nylon 66 is also a popular guitar nut material, nylon 66, especially glass fibre grades can be effectively fire retarded with halogen free products. Phosphorus-based flame retardant systems are used in these polymers and are based on aluminium diethyl phosphinate. They are designed to meet UL94 flammability tests as well as Glow Wire Ignition Tests, Glow Wire Flammability Test, main applications are in the electrical and electronics industry
16.
Diamine
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A diamine is an amine with exactly two amino groups. Diamines are used as monomers to prepare polyamides, polyimides and polyureas, in terms of quantities produced,1, 6-diaminohexane, a precursor to Nylon 6-6, is most important, followed by ethylenediamine. Vicinal diamines are a motif in many biological compounds and are used as ligands in organometallic chemistry 2 carbons. Related derivatives include the N-alkylated compounds,1, 1-dimethylethylenediamine,1, 1-dimethylethylenediamine, ethambutol,3 carbons,1, 3-diaminopropane 4 carbons, putrescine 5 carbons, cadaverine 6 carbons, hexamethylenediamine Derivatives of ethylenediamine are prominent,1, 2-diaminopropane, which is chiral. Xylylenediamines are classified as alkylamines since the amine is not directly attached to an aromatic ring, o-xylylenediamine or OXD m-xylylenediamine or MXD p-xylylenediamine or PXD Three phenylenediamines are known, o-phenylenediamine or OPD m-phenylenediamine or MPD p-phenylenediamine or PPD. 2, 5-Diaminotoluene is related to PPD but contains a group on the ring. Various N-methylated derivatives of the phenylenediamines are known, dimethyl-4-phenylenediamine, a reagent
17.
Wallace Carothers
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Wallace Hume Carothers was an American chemist, inventor and the leader of organic chemistry at DuPont, credited with the invention of nylon. Carothers was a leader at the DuPont Experimental Station laboratory, near Wilmington, Delaware. Carothers was an organic chemist who, in addition to first developing nylon, after receiving his Ph. D. he taught at several universities before he was hired by DuPont to work on fundamental research. He married Helen Sweetman on February 21,1936, Carothers had been troubled by periods of depression since his youth. Despite his success with nylon, he felt that he had not accomplished much and had run out of ideas and his daughter, Jane, was born on November 27,1937. Carothers was born on April 27,1896 in Burlington, Iowa, to Ira and he was the oldest of four children. He had one brother and two sisters, John, Isobel and Elizabeth, as a youth, Carothers was fascinated by tools and mechanical devices and spent many hours experimenting. He attended public school in Des Moines, Iowa, where he was known as a conscientious student, in September 1915, he entered Tarkio College in Missouri. Although he initially majored in English, he switched to chemistry under the influence of Arthur Pardee and he graduated from Tarkio in 1920 at the age of 24 with a bachelor of science degree. Then he went to the University of Illinois for his master of arts degree, during the 1921–22 school year, Carothers held a one-year appointment as a chemistry instructor at the University of South Dakota. It was at the University of South Dakota that he began his independent research that resulted in an article accepted by the Journal of the American Chemical Society, in this paper he measured physical properties of phenylisocyanate and of diazobenzene-imide. He went back to the University of Illinois to study for his Ph. D. under Roger Adams and his degree was awarded in 1924. He specialized in organic chemistry and minored in chemistry and mathematics. He worked as an assistant during 1922–1923 and received the Carr Fellowship for 1923–24. This was the most prestigious award offered by the university at that time and he was initiated into Alpha Chi Sigma in 1926 as a member of Zeta Chapter at the University of Illinois. Carothers stayed at the University of Illinois for two years as an instructor in organic chemistry, in 1926 Carothers moved to Harvard University. Again he was an instructor in organic chemistry, conant, who became President of Harvard College in 1933, said of Carothers, In his research, Dr. Carothers showed even at this time the high degree of originality which marked his later work. He was never content to follow the path or to accept the usual interpretations of organic reactions
18.
DuPont Experimental Station
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The DuPont Experimental Station is the largest research and development facility of E. I. du Pont de Nemours and Company. Located on the banks of the Brandywine Creek in Wilmington, Delaware, the Experimental Station is a more recent part of the DuPont legacy and is located on the DuPont Historic Corridor. The Experimental Station marked its 100th anniversary in 2003 and it was founded as an effort to move the DuPont Company from gunpowder and explosives into the new age of chemistry. The Experimental Station is east from Hagley Museum and west-southwest from the Alfred I. duPont Hospital for Children and it is home to DuPonts Central Research and most other business units of DuPont are also represented on site. Simple Crown ethers were invented by Charles J. Pedersen in 1967, there is a plaque at the Experimental Station marking the location of the lab where his work took place. For a more complete description of the inventions of the scientists and engineers of the Experimental Station, there are over 50 buildings encompassing 250,000 square meters of research space. This centralized facility allows collaborations to enhance scientific discovery, more recent successes include Suva refrigerants, the BAX food safety systems and Sorona polyester. Research and development now under way includes nanotechnology, emerging video display technologies, fuel cells, on the morning of January 24,2007, President George W. Bush became the first president to visit the Experimental Station. He saw examples of how DuPont is putting science to work to provide products for energy crops, feedstock processing. He also viewed other alternative sources and technologies dealing with energy conservation. These are all part of DuPont’s sustainable growth mission, timeline of discoveries at the DuPont Experimental Station Experimental Station in the history of DuPont
19.
IG Farben
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IG Farben was a German chemical and pharmaceutical industry conglomerate. Its name is taken from Interessen-Gemeinschaft Farbenindustrie AktienGesellschaft, the company was formed in 1925 from a number of major chemical companies that had been working together closely since World War I. During its heyday, IG Farben was both the largest company in Europe overall and the largest chemical and pharmaceutical company in the world, IG Farben scientists made fundamental contributions to all areas of chemistry and the pharmaceutical industry. Notably IG Farben scientists discovered the first antibiotic, fundamentally reformed medical research, otto Bayer discovered the polyaddition for the synthesis of polyurethane in 1937. Several IG Farben scientists were awarded Nobel Prizes, Carl Bosch and Friedrich Bergius were awarded the Nobel Prize in Chemistry in 1931 in recognition of their contributions to the invention and development of chemical high pressure methods. Gerhard Domagk was awarded the Nobel Prize in Physiology or Medicine in 1939 for the discovery of the effects of prontosil. Kurt Alder was awarded the Nobel Prize in Chemistry in 1950 for his discovery, following the Nazi takeover of Germany, the company became embroiled in the Nazi regimes policies as a large government contractor. In 1951, IG Farben was split into its four largest original constituent companies, the current main successor companies are AGFA, BASF, Bayer and Sanofi. IG Farben was founded on 9 December 1925, as a merger of the six companies. Weiler Ter Meer At the beginning of the 20th century, the German chemical industry dominated the market for synthetic dyes. Weiler-ter Meer concentrated on high-quality specialty dyes, in 1913, these eight firms produced almost 90% of the world supply of dyestuffs and sold about 80% of their production abroad. Because of this situation, the economic historian Alfred Chandler called the German dye companies the worlds first truly managerial industrial enterprises. With the world market for synthetic dyes and other chemical products dominated by the German industry, although cartels were attempted, they lasted at most for a few years. Others argued for the formation of a pool or Interessen-Gemeinschaft. In contrast, the chairman of Bayer, Carl Duisberg, argued for a merger. During a trip to the United States in the spring of 1903 he had visited several of the large American trusts such as Standard Oil, U. S. Steel, International Paper and Alcoa. In 1904, after having returned to Germany he proposed a merger of the producers of dye and pharmaceuticals in a memorandum to Gustav von Brüning. Hoechst and several pharmaceutical firms refused to join, instead, Hoechst and Cassella made an alliance based on mutual equity stakes in 1904
20.
Nylon 6
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Nylon 6 or polycaprolactam is a polymer developed by Paul Schlack at IG Farben to reproduce the properties of nylon 6,6 without violating the patent on its production. Its competition with nylon 6,6 and the example it set have also shaped the economics of the fiber industry. It is sold under trade names including Perlon, Dederon, Nylatron, Capron, Ultramid, Akulon, Kapron. Nylon 6 can be modified using comonomers or stabilizers during polymerization to introduce new chain end or functional groups, it’s often done to change its dyeability or flame retardance. Nylon 6 is synthesized by ring-opening polymerization of caprolactam, caprolactam has 6 carbons, hence Nylon 6. When caprolactam is heated at about 533 K in an atmosphere of nitrogen for about 4-5 hours. Then the molten mass is passed through spinnerets to form fibres of Nylon 6, during polymerization, the amide bond within each caprolactam molecule is broken, with the active groups on each side re-forming two new bonds as the monomer becomes part of the polymer backbone. Unlike nylon 6,6, in which the direction of the amide bond reverses at each bond, Nylon 6 fibres are tough, possessing high tensile strength, as well as elasticity and lustre. They are wrinkleproof and highly resistant to abrasion and chemicals such as acids, the fibres can absorb up to 2. 4% of water, although this lowers tensile strength. The glass transition temperature of Nylon 6 is 47 °C, as a synthetic fiber, Nylon 6 is generally white but can be dyed to in a solution bath prior to production for different color results. Its tenacity is between 6 and 8.5 gm/den with a density of 1.14 gm/cc and its melting point is at 215 °C and can protect heat up to 150 °C on average. In 2010 over 4 million tons of polyamide 6 were produced, 60% of 2008 production went to fibre applications, engineering resins took 30% and films 10%. Nylon 6 finds application in a range of products requiring materials of high strength. It is widely used for gears, fittings, and bearings, in industry for underthehood parts. Nylon 6 is used as thread in bristles for toothbrushes, surgical sutures, and strings for acoustic and classical instruments, including guitars, sitars, violins, violas. It is also used in the manufacture of a variety of threads, ropes, filaments, nets. It can also be used in gun frames, such as used by Glock. In manufacturing, Nylon 6 is used as washers and it has the potential to be reused as a technical raw material for the production of new Nylon 6, by depolymerization to caprolactam
21.
Caprolactam
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Caprolactam is an organic compound with the formula 5CNH. This colourless solid is a lactam of caproic acid, approximately 4.5 billion kilograms are produced annually. Caprolactam is the precursor to Nylon 6, a widely used synthetic polymer, caprolactam was first described in the late 1800s when it was prepared by the cyclization of ε-aminocaproic acid, the product of the hydrolysis of caprolactam. Given the commercial significance of Nylon-6, many methods have developed for the production of caprolactam. Most of the caprolactam is synthesised from cyclohexanone, which is first converted to its oxime, treatment of this oxime with acid induces the Beckmann rearrangement to give caprolactam, The immediate product of the acid-induced rearrangement is the bisulfate salt of caprolactam. This salt is neutralized with ammonia to release the free lactam, in optimizing the industrial practices, much attention is directed toward minimizing the production of ammonium salts. The other major route involves formation of the oxime from cyclohexane using nitrosyl chloride. The advantage of this method is that cyclohexane is less expensive than cyclohexanone, in earlier times, caprolactam was prepared by treatment of caprolactone with ammonia. Cyclohexanone with hydrazoic acid has also been reported and this is known as a Schmidt ring expansion. Almost all caprolactam produced goes into the manufacture of Nylon-6, the conversion entails a ring-opening polymerization, n 5CNH → n Nylon-6 is widely used in fibers and plastics. In situ anionic polymerization is employed for cast nylon production where conversion from ε-caprolactam to Nylon-6 takes place inside a mold, in conjunction with endless fiber processing the term thermoplastic resin transfer molding is often used. Caprolactam is an irritant and is toxic, with an LD50 of 1.1 g/kg. In 1991, it was included on the list of air pollutants by the U. S. Clean Air Act of 1990. It was subsequently removed from the list in 1996, in water, caprolactam hydrolyzes to aminocaproic acid, which is used medicinally. As of 2016 caprolactam had the status of being the only chemical in the International Agency for Research on Cancers lowest hazard category, Group 4. Currently, there is no official permissible exposure limit set for workers handling caprolactam in the United States, the recommended exposure limit is set at 1 mg/m3 over an eight-hour work shift for caprolactam dusts and vapors. The short-term exposure limit is set at 3 mg/m3 for caprolactam dusts and vapors
22.
Bristle
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A bristle is a stiff hair or feather, either on an animal, such as a pig, or on a tool such as a brush or broom. Synthetic materials such as nylon are used to make bristles in items such as brooms. Bristles are often used to make brushes for cleaning purposes, as they are strongly abrasive, common examples include the toothbrush, the bristle brush and the scrub brush are common household cleaning tools, often used to remove dirt or grease from pots and pans. Bristles are also used on other than for cleaning, notably paintbrushes. Bristles are distinguished as flagged or unflagged, these are known as flocked or unflocked bristles. In cleaning applications, flagged bristles are suited for dry cleaning, in painting, flagged bristles yield more even application. Bristles are found on pig breeds, instead of fur, because the density is less than with fur, pigs are vulnerable to sunburn. One breed, the Tamworth pig, is endowed with a very dense bristle structure such that sunburn damage to skin is minimized, animals named for their bristles include bristlebirds, the bristle-thighed curlew, the bristle-spined porcupine, and the Trinity bristle snail. Bristles also anchor worms to the soil to help the worm move, hairbrush Types of Bristle Materials Used for Brushes
23.
Toothbrush
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The toothbrush is an oral hygiene instrument used to clean the teeth, gums, and tongue. It consists of a head of tightly clustered bristles mounted on a handle which facilitates the cleaning of hard to reach areas of the mouth, Toothbrushes are available with different bristle textures, sizes, and forms. Most dentists recommend using a soft toothbrush since hard bristled toothbrushes can damage tooth enamel, before the invention of the toothbrush a variety of oral hygiene measures had been used. This has been verified by excavations in which chew sticks, tree twigs, bird feathers, animal bones, the predecessor of the toothbrush is the chew stick. Chew sticks were twigs with frayed ends used to brush the teeth while the end was used as a toothpick. The earliest chew sticks were discovered in Babylonia in 3500 BC, an Egyptian tomb dating from 3000 BC, the Greeks and Romans used toothpicks to clean their teeth and toothpick like twigs have been excavated in Qin Dynasty tombs. Miswaks have been used by Muslims since 7th century, the first bristle toothbrush resembling the modern one was found in China. Used during the Tang Dynasty, it consisted of hog bristles, the bristles were sourced from hogs living in Siberia and northern China because the colder temperatures provided firmer bristles. They were attached to a handle manufactured from bamboo or bone, in 1223, Japanese Zen master Dōgen Kigen recorded on Shōbōgenzō that he saw monks in China clean their teeth with brushes made of horsetail hairs attached to an oxbone handle. The bristle toothbrush spread to Europe, brought from China to Europe by travellers and it was adopted in Europe during the 17th century. The earliest identified use of the toothbrush in English was in the autobiography of Anthony Wood who wrote in 1690 that he had bought a toothbrush from J. Barret. Europeans found the hog bristle toothbrushes imported from China too firm, mass produced toothbrushes made with horse or boar bristle continued to be imported to England from China until the mid 20th century. In Europe, William Addis of England is believed to have produced the first mass produced toothbrush in 1780, in 1770, he had been jailed for causing a riot. While in prison he decided that using a rag with soot and salt on the teeth was ineffective, after his release, he became wealthy after starting a business manufacturing toothbrushes. He died in 1808 leaving the business to his eldest son and it stayed in family ownership until 1996. Under the name Wisdom Toothbrushes, the company now manufactures 70 million toothbrushes per year in the UK, by 1840 toothbrushes were being mass produced in England, France, Germany, and Japan. Pig bristles were used for cheaper toothbrushes and badger hair for the expensive ones. The first patent for a toothbrush was granted to H. N. Wadsworth in 1857 in the United States, the rather advanced design had a bone handle with holes bored into it for the Siberian boar hair bristles
24.
Stocking
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Stockings are close-fitting, variously elastic garments covering the leg from the foot up to the knee or possibly part or all of the thigh. Stockings vary in color, design, and transparency, today, stockings are primarily worn for fashion and aesthetics, usually in association with mid-length skirts. By analogy, the stocking is also used to describe a type of horse marking in which the white coloring extends from the horses hoof to just above the knee. Historically, even though the word sock is at least as ancient in origin, what men normally wore were often referred to as stockings, before the 1590s, stockings were made of woven cloth. The first knitting machines were for making stockings, the stockings themselves were made of cotton, linen, wool or silk. A polished cotton called lisle was common, as were made in the town of Balbriggan. Before the 1920s, stockings, if worn, were worn for warmth, in the 1920s, as hemlines of dresses rose, women began to wear stockings to cover their exposed legs. Those stockings were sheer, first made of silk or rayon, the introduction of nylon in 1939 by chemical company DuPont began a high demand for stockings in the United States with up to 4 million pairs being purchased in one day. Nylon stockings were cheap, durable, and sheer compared to their cotton, when America entered World War II, DuPont ceased production of nylon stockings and retooled their factories to produce parachutes, airplane cords, and rope. This led to a shortage and the creation of a market for stockings. At the end of the war DuPont announced that the company would return to producing stockings and this led to a series of disturbances in American stores known as the nylon riots until DuPont was able to ramp up production. Today, stockings are made using knitted wool, silk. The introduction of commercial pantyhose in 1959 gave an alternative to stockings, a main reason for this was the trend towards higher hemlines on dresses. In 1970, U. S. sales of pantyhose exceeded stockings for the first time, beginning in 1987, sales of pantyhose started a slight decline due to the newly invented hold-ups, but still remain the most sold kind of hosiery. Stockings are still preferred to pantyhose for a number of reasons. Stockings, on the hand, provide ventilation in the crotch. Both nylon stockings and pantyhose in being sheer share the advantage of being quick-drying compared to pants, spare pairs are also easy to carry if they are ruined. If laddered they can be replaced one at a time provides a cost advantage over tights
25.
1939 New York World's Fair
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Many countries around the world participated in it, and over 44 million people attended its exhibits in two seasons. The NYWF of 1939–1940 was the first exposition to be based on the future, with a slogan of Dawn of a New Day. To its visitors the Fair will say, Here are the materials, ideas and these are the tools with which the World of Tomorrow must be made. They are all interesting and much effort has been expended to lay them before you in an interesting way, familiarity with today is the best preparation for the future. Within six months of the Fairs opening, the Second World War would begin, in 1935, at the height of the Great Depression, a group of New York City businessmen decided to create an international exposition to lift the city and the country out of depression. Not long after, these men formed the New York Worlds Fair Corporation, the NYWFC elected former chief of police Grover Whalen as the president of their committee. This event turned the area into a City park after the exposition closed, edward Bernays directed public relations of the fair in 1939, which he called democricity. Promotion of this event took many forms. Howard Hughes flew a special Worlds Fair flight around the world to promote the fair in 1938, on April 30,1939, a very hot Sunday, the fair had its grand opening, with 206,000 people in attendance. The April 30 date coincided with the 150th anniversary of George Washingtons inauguration, in Lower Manhattan, although many of the pavilions and other facilities were not quite ready for this opening, it was put on with pomp and great celebration. David Sarnoff, then president of RCA and an advocate of television. On April 30,1939, the ceremony and President Roosevelts speech were seen on black. NBC used the event to inaugurate regularly scheduled broadcasts in New York City over their station W2XBS. An estimated 1,000 people viewed the Roosevelt telecast on about 200 television sets scattered throughout the New York metropolitan area. In order to convince visitors that the television sets were not a trick. As part of the exhibit at the RCA pavilion, visitors could see themselves on television, there were also television demonstrations at the General Electric and Westinghouse pavilions. During this formal introduction at the fair, television became available for public purchase at various stores in the New York City area. After Albert Einstein gave a speech that discussed cosmic rays, the lights were ceremonially lit
26.
Parachute
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A parachute is a device used to slow the motion of an object through an atmosphere by creating drag. Parachutes are usually out of light, strong cloth, originally silk. Parachutes often take the shape of a dome, but shapes may vary including some taking the shape of an inverted dome, depending on the situation, parachutes are used with a variety of loads, including people, food, equipment, space capsules, and bombs. Drogue chutes are used to aid horizontal deceleration of a vehicle, the earliest evidence for the parachute dates back to the Renaissance period. The oldest parachute design appears in a manuscript from 1470s Renaissance Italy. As a safety measure, four straps run from the ends of the rods to a waist belt, shortly after, a more sophisticated parachute was sketched by the polymath Leonardo da Vinci in his Codex Atlanticus dated to ca. Here, the scale of the parachute is in a more favorable proportion to the weight of the jumper, Leonardos canopy was held open by a square wooden frame, which alters the shape of the parachute from conical to pyramidal. It is not known whether the Italian inventor was influenced by the earlier design, the feasibility of Leonardos pyramidal design was successfully tested in 2000 by Briton Adrian Nicholas and again in 2008 by the Swiss skydiver Olivier Vietti-Teppa. The Croatian polymath and inventor Faust Vrančić examined da Vincis parachute sketch and he kept the square frame, but replaced the canopy with a bulging sail-like piece of cloth that he came to realize decelerates the fall more effectively. However, in book, John Wilkins wrote about flying. The modern parachute was invented in the late 18th century by Louis-Sébastien Lenormand in France, Lenormand also sketched his device beforehand. Two years later, in 1785, Lenormand coined the word parachute by hybridizing a Latin prefix para, and chute, also in 1785, Jean-Pierre Blanchard demonstrated it as a means of safely disembarking from a hot-air balloon. Subsequent development of the focused on it becoming more compact. In 1797, André Garnerin made the first descent using such a parachute, Garnerin also invented the vented parachute, which improved the stability of the fall. In 1907 Charles Broadwick demonstrated two key advances in the parachute he used to jump from hot air balloons at fairs and he folded his parachute into a pack he wore on his back. And the parachute was pulled from the pack by a line attached to the balloon. When Broadwick jumped from the balloon, the line became taut, pulled the parachute from the pack. In 1911 a successful test took place with a dummy at the Eiffel tower in Paris, the puppets weight was 75 kg, the parachutes weight was 21 kg
27.
Parachute cord
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Parachute cord is a lightweight nylon kernmantle rope originally used in the suspension lines of parachutes. This cord is useful for other tasks and is now used as a general purpose utility cord by both military personnel and civilians. This versatile cord was used by astronauts during the 82nd Space Shuttle mission to repair the Hubble Space Telescope. The braided sheath has a number of interwoven strands for its size. The all-nylon construction makes paracord fairly elastic, current technical standards for the manufacture of cord for use in parachutes are published by the Parachute Industry Association. The US military MIL-C-5040H standard required the material to be nylon, similar styles of cord are manufactured with other materials such as polyester. Historically associated with units and divisions, paracord is today used by many military units in almost any situation where light cordage is needed. When threaded with beads, paracord may be used as a counter to estimate ground covered by foot. The yarns of the core can also be removed when finer string is needed, for instance as sewing thread to repair gear, or to be used as fishing line in a survival situation. The nylon sheath is used alone, the yarn in the core removed. Ends of the cord are almost always melted and crimped to prevent fraying, in addition to purely utility functions, paracord can be used to fashion knotted or braided bracelets, lanyards, belts, and other decorative items. These are sometimes tied in a fashion that can easily be unraveled for use in a survival situation, some companies use paracord in conjunction with other survival components to create everyday wearable survival kits. The same properties which soldiers appreciate in paracord are also useful in civilian applications, after World War II parachute cord became available to civilians, first as military surplus and then as a common retail product from various surplus stores and websites. A given product labelled as paracord may not correspond to a military type and can be of differing construction, quality. Particularly poor quality examples may have significantly fewer strands in the sheath or core, cores constructed of fiber rather than individual yarns. Paracord has also used for whipmaking. The durability and versatility of this material has proved beneficial for performing whip crackers, since nylon does not rot or mildew, it has become known as an all-weather material for whipmaking. Hikers and outdoor sports enthusiasts use survival bracelets made of several feet of paracord which is woven into a compact
28.
Plastic
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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
29.
Polymer
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A polymer is a large molecule, or macromolecule, composed of many repeated subunits. Because of their range of properties, both synthetic and natural polymers play an essential and ubiquitous role in everyday life. Polymers range from familiar synthetic plastics such as polystyrene to natural biopolymers such as DNA and proteins that are fundamental to biological structure, Polymers, both natural and synthetic, are created via polymerization of many small molecules, known as monomers. The units composing polymers derive, actually or conceptually, from molecules of low molecular mass. The term was coined in 1833 by Jöns Jacob Berzelius, though with a distinct from the modern IUPAC definition. The modern concept of polymers as covalently bonded macromolecular structures was proposed in 1920 by Hermann Staudinger, Polymers are studied in the fields of biophysics and macromolecular science, and polymer science. Polyisoprene of latex rubber is an example of a polymer. In biological contexts, essentially all biological macromolecules—i. e, proteins, nucleic acids, and polysaccharides—are purely polymeric, or are composed in large part of polymeric components—e. g. Isoprenylated/lipid-modified glycoproteins, where small molecules and oligosaccharide modifications occur on the polyamide backbone of the protein. The simplest theoretical models for polymers are ideal chains, Polymers are of two types, Natural polymeric materials such as shellac, amber, wool, silk and natural rubber have been used for centuries. A variety of natural polymers exist, such as cellulose. Most commonly, the continuously linked backbone of a used for the preparation of plastics consists mainly of carbon atoms. A simple example is polyethylene, whose repeating unit is based on ethylene monomer, however, other structures do exist, for example, elements such as silicon form familiar materials such as silicones, examples being Silly Putty and waterproof plumbing sealant. Oxygen is also present in polymer backbones, such as those of polyethylene glycol, polysaccharides. Polymerization is the process of combining many small molecules known as monomers into a covalently bonded chain or network, during the polymerization process, some chemical groups may be lost from each monomer. This is the case, for example, in the polymerization of PET polyester, the distinct piece of each monomer that is incorporated into the polymer is known as a repeat unit or monomer residue. Laboratory synthetic methods are divided into two categories, step-growth polymerization and chain-growth polymerization. However, some methods such as plasma polymerization do not fit neatly into either category
30.
Peptide bond
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A peptide bond is a covalent chemical bond linking two consecutive amino acid monomers along a peptide or protein chain. When two amino acids form a dipeptide through a peptide bond it is called condensation, in condensation, two amino acids approach each other, with the acid moiety of one coming near the amino moiety of the other. One loses a hydrogen and oxygen from its group and the other loses a hydrogen from its amino group. This reaction produces a molecule of water and two amino acids joined by a peptide bond, the two joined amino acids are called a dipeptide. The formation of the peptide bond consumes energy, which, in living systems, is derived from ATP, polypeptides and proteins are chains of amino acids held together by peptide bonds. Living organisms employ enzymes to produce polypeptides, and ribosomes to produce proteins, peptides are synthesized by specific enzymes. For example, the tripeptide glutathione is synthesized in two steps from free amino acids, by two enzymes, gamma-glutamylcysteine synthetase and glutathione synthetase, a peptide bond can be broken by hydrolysis. In the presence of water they will break down and release 8–16 kilojoule/mol of free energy, in living organisms, the process is catalyzed by enzymes known as peptidases or proteases. The wavelength of absorption for a bond is 190–230 nm. Significant delocalisation of the pair of electrons on the nitrogen atom gives the group a partial double bond character. The partial double bond renders the amide group planar, occurring in either the cis or trans isomers. In the unfolded state of proteins, the groups are free to isomerize. The trans form is preferred overwhelmingly in most peptide bonds, however, X-Pro peptide groups tend to have a roughly 3,1 ratio, presumably because the symmetry between the C α and C δ atoms of proline makes the cis and trans isomers nearly equal in energy. The dihedral angle associated with the group is denoted ω, ω =0 ∘ for the cis isomer. Amide groups can isomerize about the C-N bond between the cis and trans forms, albeit slowly, the transition states ω = ±90 ∘ requires that the partial double bond be broken, so that the activation energy is roughly 80 kilojoule/mol. Conformational protein folding is much faster than cis-trans isomerization. A nonnative isomer of some groups can disrupt the conformational folding significantly. However, not all groups have the same effect on folding
31.
Protein
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Proteins are large biomolecules, or macromolecules, consisting of one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, responding to stimuli, a linear chain of amino acid residues is called a polypeptide. A protein contains at least one long polypeptide, short polypeptides, containing less than 20–30 residues, are rarely considered to be proteins and are commonly called peptides, or sometimes oligopeptides. The individual amino acid residues are bonded together by peptide bonds, the sequence of amino acid residues in a protein is defined by the sequence of a gene, which is encoded in the genetic code. In general, the code specifies 20 standard amino acids, however. Sometimes proteins have non-peptide groups attached, which can be called prosthetic groups or cofactors, proteins can also work together to achieve a particular function, and they often associate to form stable protein complexes. Once formed, proteins only exist for a period of time and are then degraded and recycled by the cells machinery through the process of protein turnover. A proteins lifespan is measured in terms of its half-life and covers a wide range and they can exist for minutes or years with an average lifespan of 1–2 days in mammalian cells. Abnormal and or misfolded proteins are degraded more rapidly due to being targeted for destruction or due to being unstable. Like other biological macromolecules such as polysaccharides and nucleic acids, proteins are essential parts of organisms, many proteins are enzymes that catalyse biochemical reactions and are vital to metabolism. Proteins also have structural or mechanical functions, such as actin and myosin in muscle and the proteins in the cytoskeleton, other proteins are important in cell signaling, immune responses, cell adhesion, and the cell cycle. In animals, proteins are needed in the diet to provide the essential amino acids that cannot be synthesized, digestion breaks the proteins down for use in the metabolism. Methods commonly used to study structure and function include immunohistochemistry, site-directed mutagenesis, X-ray crystallography, nuclear magnetic resonance. Most proteins consist of linear polymers built from series of up to 20 different L-α-amino acids, all proteinogenic amino acids possess common structural features, including an α-carbon to which an amino group, a carboxyl group, and a variable side chain are bonded. Only proline differs from this structure as it contains an unusual ring to the N-end amine group. The amino acids in a chain are linked by peptide bonds. Once linked in the chain, an individual amino acid is called a residue, and the linked series of carbon, nitrogen. The peptide bond has two forms that contribute some double-bond character and inhibit rotation around its axis, so that the alpha carbons are roughly coplanar
32.
Lactam
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A lactam is a cyclic amide. The term is a portmanteau of the words lactone + amide, general synthetic methods exist for the organic synthesis of lactams. Lactams form by the rearrangement of oximes in the Beckmann rearrangement. Lactams form from cyclic ketones and hydrazoic acid in the Schmidt reaction, lactams form from cyclisation of amino acids. Lactams form from intramolecular attack of linear acyl derivatives from the nucleophilic abstraction reaction, in iodolactamization an iminium ion reacts with an halonium ion formed in situ by reaction of an alkene with iodine. At lower temp, β-lactam is the preferred product, at optimum temperatures, a highly useful γ-lactam known as Vince Lactam is obtained. Lactim is a cyclic carboximidic acid compound characterized by an endocyclic carbon-nitrogen double bond and it is formed when lactam undergoes tautomerization. β-Lactam β-Lactam antibiotics, which includes penicillins 2-Pyrrolidone 2-Piperidinone Caprolactam
33.
Dicarboxylic acid
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A dicarboxylic acid is an organic compound containing two carboxyl functional groups. The general molecular formula for dicarboxylic acids can be written as HO2C−R−CO2H, in general, dicarboxylic acids show similar chemical behavior and reactivity to monocarboxylic acids. Dicarboxylic acids are used in the preparation of copolymers such as polyamides. The most widely used dicarboxylic acid in the industry is adipic acid, other examples of dicarboxylic acids include aspartic acid and glutamic acid, two amino acids in the human body. The PubChem links gives access to a wealth of information on the compounds, adipic acid, despite its name, is not a normal constituent of natural lipids but is a product of oxidative rancidity. It was first obtained by oxidation of castor oil with nitric acid and it is now produced industrially by oxidation of cyclohexanol or cyclohexane, mainly for the production of Nylon 6-6. Pimelic acid was also first isolated from oxidized oil, derivatives of pimelic acid are involved in the biosynthesis of lysine. Suberic acid was first produced by nitric acid oxidation of cork and this acid is also produced when castor oil is oxidised. Suberic acid is used in the manufacture of alkyd resins and in the synthesis of polyamides, azelaic acids name stems from the action of nitric acid oxidation of oleic acid or elaidic acid. It was detected among products of rancid fats and its origin explains for its presence in poorly preserved samples of linseed oil and in specimens of ointment removed from Egyptian tombs 5000 years old. Azelaic acid was prepared by oxidation of oleic acid with potassium permanganate, azelaic acid is used, as simple esters or branched-chain esters) in the manufacture of plasticizers, lubricants and greases. Azelaic acid is now used in cosmetics and it displays bacteriostatic and bactericidal properties against a variety of aerobic and anaerobic micro-organisms present on acne-bearing skin. Azelaic acid was identified as a molecule that accumulated at elevated levels in parts of plants and was shown to be able to enhance the resistance of plants to infections. Thenard isolated this compound from distillation products of beef tallow in 1802 and it is produced industrially by alkali fission of castor oil. Sebacic acid and its derivatives have a variety of uses as plasticizers, lubricants, diffusion pump oils, cosmetics, candles. It is also used in the synthesis of polyamide, as nylon, brassylic acid can be produced from erucic acid by ozonolysis but also by microorganisms from tridecane. This diacid is produced on a commercial scale in Japan for the manufacture of fragrances. Dodecanedioic acid is used in the production of nylon, polyamides, coatings, adhesives, greases, polyesters, dyestuffs, detergents, flame retardants and it is now produced by fermentation of long-chain alkanes with a specific strain of Candida tropicalis
34.
Textile
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A textile or cloth is a flexible material consisting of a network of natural or artificial fibres. Yarn is produced by spinning raw fibres of wool, flax, cotton, hemp, Textiles are formed by weaving, knitting, crocheting, knotting, or felting. The words fabric and cloth are used in textile assembly trades as synonyms for textile, however, there are subtle differences in these terms in specialized usage. Textile refers to any material made of interlacing fibres, a fabric is a material made through weaving, knitting, spreading, crocheting, or bonding that may be used in production of further goods. Cloth may be used synonymously with fabric but is often a piece of fabric used for a specific purpose. The word textile is from Latin, from the adjective textilis, meaning woven, from textus, the word cloth derives from the Old English clað, meaning a cloth, woven or felted material to wrap around one, from Proto-Germanic kalithaz. The discovery of dyed flax fibres in a cave in the Republic of Georgia dated to 34,000 BCE suggests textile-like materials were made even in prehistoric times. The production of textiles is a craft whose speed and scale of production has been altered almost beyond recognition by industrialization, however, for the main types of textiles, plain weave, twill, or satin weave, there is little difference between the ancient and modern methods. Textiles have an assortment of uses, the most common of which are for clothing and for such as bags. In the household they are used in carpeting, upholstered furnishings, window shades, towels, coverings for tables, beds, and other flat surfaces, in the workplace they are used in industrial and scientific processes such as filtering. Textiles are used in traditional crafts such as sewing, quilting. Textiles for industrial purposes, and chosen for other than their appearance, are commonly referred to as technical textiles. Technical textiles include textile structures for applications, medical textiles, geotextiles, agrotextiles. In all these applications stringent performance requirements must be met, woven of threads coated with zinc oxide nanowires, laboratory fabric has been shown capable of self-powering nanosystems using vibrations created by everyday actions like wind or body movements. Fashion designers commonly rely on textile designs to set their fashion collections apart from others, armani, the late Gianni Versace, and Emilio Pucci can be easily recognized by their signature print driven designs. Textiles can be made from many materials and these materials come from four main sources, animal, plant, mineral, and synthetic. In the past, all textiles were made from natural fibres, including plant, animal, in the 20th century, these were supplemented by artificial fibres made from petroleum. Textiles are made in various strengths and degrees of durability, from the finest gossamer to the sturdiest canvas, microfibre refers to fibres made of strands thinner than one denier
35.
World War I
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World War I, also known as the First World War, the Great War, or the War to End All Wars, was a global war originating in Europe that lasted from 28 July 1914 to 11 November 1918. More than 70 million military personnel, including 60 million Europeans, were mobilised in one of the largest wars in history and it was one of the deadliest conflicts in history, and paved the way for major political changes, including revolutions in many of the nations involved. The war drew in all the worlds great powers, assembled in two opposing alliances, the Allies versus the Central Powers of Germany and Austria-Hungary. These alliances were reorganised and expanded as more nations entered the war, Italy, Japan, the trigger for the war was the assassination of Archduke Franz Ferdinand of Austria, heir to the throne of Austria-Hungary, by Yugoslav nationalist Gavrilo Princip in Sarajevo on 28 June 1914. This set off a crisis when Austria-Hungary delivered an ultimatum to the Kingdom of Serbia. Within weeks, the powers were at war and the conflict soon spread around the world. On 25 July Russia began mobilisation and on 28 July, the Austro-Hungarians declared war on Serbia, Germany presented an ultimatum to Russia to demobilise, and when this was refused, declared war on Russia on 1 August. Germany then invaded neutral Belgium and Luxembourg before moving towards France, after the German march on Paris was halted, what became known as the Western Front settled into a battle of attrition, with a trench line that changed little until 1917. On the Eastern Front, the Russian army was successful against the Austro-Hungarians, in November 1914, the Ottoman Empire joined the Central Powers, opening fronts in the Caucasus, Mesopotamia and the Sinai. In 1915, Italy joined the Allies and Bulgaria joined the Central Powers, Romania joined the Allies in 1916, after a stunning German offensive along the Western Front in the spring of 1918, the Allies rallied and drove back the Germans in a series of successful offensives. By the end of the war or soon after, the German Empire, Russian Empire, Austro-Hungarian Empire, national borders were redrawn, with several independent nations restored or created, and Germanys colonies were parceled out among the victors. During the Paris Peace Conference of 1919, the Big Four imposed their terms in a series of treaties, the League of Nations was formed with the aim of preventing any repetition of such a conflict. This effort failed, and economic depression, renewed nationalism, weakened successor states, and feelings of humiliation eventually contributed to World War II. From the time of its start until the approach of World War II, at the time, it was also sometimes called the war to end war or the war to end all wars due to its then-unparalleled scale and devastation. In Canada, Macleans magazine in October 1914 wrote, Some wars name themselves, during the interwar period, the war was most often called the World War and the Great War in English-speaking countries. Will become the first world war in the sense of the word. These began in 1815, with the Holy Alliance between Prussia, Russia, and Austria, when Germany was united in 1871, Prussia became part of the new German nation. Soon after, in October 1873, German Chancellor Otto von Bismarck negotiated the League of the Three Emperors between the monarchs of Austria-Hungary, Russia and Germany
36.
Rayon
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Rayon is a manufactured regenerated cellulose fiber. It is made from purified cellulose, primarily from wood pulp and it is then dissolved and forced through a spinneret to produce filaments which are chemically solidified, resulting in synthetic fibers of nearly pure cellulose. Because rayon is manufactured from naturally occurring polymers, it is considered a semi-synthetic fiber, specific types of rayon include viscose, modal and lyocell, each of which differs in manufacturing process and properties of the finished product. The solubility of nitrocellulose in organic solvents such as ether and acetone was the basis for the first artificial silk by Georges Audemars in about 1855, commercial production started in 1891, but the result was flammable and more expensive than cellulose acetate or cuprammonium rayon. Because of this expense, production ceased early in the 1900s, nitrocellulose was briefly known as mother-in-law silk. Nathan Rosenstein invented the process by which he turned rayon from a hard fiber to a fabric. This allowed rayon to become a popular raw material in textiles, paul Schützenberger discovered that cellulose reacts with acetic anhydride to form cellulose acetate. The triacetate is soluble only in making the method expensive. The discovery that hydrolyzed cellulose acetate is soluble in polar solvents, like acetone, made production of cellulose acetate fibers cheap. The Swiss chemist Matthias Eduard Schweizer discovered that dissolved in tetraaminecopper dihydroxide. Max Fremery and Johann Urban developed a method to produce carbon fibers for use in light bulbs in 1897, Production of cuprammonium rayon for textiles started in 1899 in the Vereinigte Glanzstoff Fabriken AG in Oberbruch near Aachen. Improvement by the J. P. Bemberg AG in 1904 made the artificial silk a product comparable to real silk, in 1894, English chemist Charles Frederick Cross, and his collaborators Edward John Bevan, and Clayton Beadle patented their artificial silk. They named their material viscose, because its production involved the intermediacy of a viscous solution. The process built on the reaction of cellulose with a strong base, the xanthate is then converted back to a cellulose fiber in a subsequent step. The first commercial viscose rayon was produced by the U. K. company Courtaulds Fibres in 1905, Courtaulds formed an American division, American Viscose, to produce their formulation in the United States in 1910. The name rayon was adopted in 1924, with viscose being used for the organic liquid used to make both rayon and cellophane. In Europe, though, the fabric itself became known as viscose, the viscose method can use wood as a source of cellulose, whereas other routes to rayon require lignin-free cellulose as starting material. The use of sources of cellulose makes viscose cheaper, so it was used on a larger scale than the other methods
37.
World's fair
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A worlds fair, world fair, world exposition, or universal exposition is a large international exhibition designed to showcase achievements of nations. These exhibitions vary in character and are held in varying parts of the world, the next world Expo is Expo 2020 and is to be held in Dubai, UAE. Since the 1928 Convention Relating to International Exhibitions came into force, bIE-approved fairs are of three types, universal, specialized and horticultural. They usually last from three weeks to six months, Worlds fairs originated in the French tradition of national exhibitions, a tradition that culminated with the French Industrial Exposition of 1844 held in Paris. This fair was followed by other exhibitions in continental Europe. The best-known first World Expo was held in The Crystal Palace in Hyde Park, London, United Kingdom, in 1851, under the title Great Exhibition of the Works of Industry of All Nations. The Great Exhibition, as it is called, was an idea of Prince Albert, Queen Victorias husband. It influenced the development of aspects of society, including art-and-design education, international trade and relations. This expo was the most obvious precedent for the international exhibitions, later called worlds fairs. Since their inception in 1851, the character of world expositions has evolved, three eras can be distinguished, the era of industrialization, the era of cultural exchange, and the era of nation branding. The first era could be called the era of industrialization and covered, roughly, in these days, world expositions were especially focused on trade, and were famous for the display of technological inventions and advancements. World expositions were the platforms where the state-of-the-art in science and technology from around the world were brought together, inventions such as the telephone were first presented during this era. An important part of the image of worlds fairs stems from this first era, the 1939–40 New York Worlds Fair diverged from the original focus of the worlds fair expositions. From then on, worlds fairs adopted specific cultural themes, they forecasted a future for society. Technological innovations were no longer the primary exhibits at fairs, the fairs encouraged effective intercultural communication for the exchange of innovation. The 1967 International and Universal Exposition in Montreal was promoted under the name Expo 67, event organizers retired the term worlds fair in favor of expo. From Expo 88 in Brisbane onwards, countries started to use world expositions more widely, finland, Japan, Canada, France and Spain are cases in point. A large study by Tjaco Walvis called Expo 2000 Hanover in Numbers showed that improving national image was the primary goal for 73% of the countries at Expo 2000
38.
Hermann Staudinger
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Hermann Staudinger was a German organic chemist who demonstrated the existence of macromolecules, which he characterized as polymers. For this work he received the 1953 Nobel Prize in Chemistry and he is also known for his discovery of ketenes and of the Staudinger reaction. Hermann Staudinger was born in 1881 in Worms, after receiving his Ph. D. from the University of Halle in 1903, Staudinger took a position at the University of Strasbourg. It was here that he discovered the ketenes, a family of molecules characterized by the general depicted in Figure 1. Ketenes would prove an important intermediate for the production of yet-to-be-discovered antibiotics such as penicillin and amoxicillin. In 1907, Staudinger began an assistant professorship at the Technical University of Karlsruhe, here, he successfully isolated a number of useful organic compounds as more completely reviewed by Rolf Mülhaupt. In 1912, Staudinger took on a new position at the Swiss Federal Institute of Technology in Zurich, one of his earliest discoveries came in 1919, when he and colleague Meyer reported that azides react with triphenylphosphine to form phosphazide. This reaction – commonly referred to as the Staudinger reaction – produces a high phosphazide yield. While at Karlsruhe and later, Zurich, Staudinger began research in the chemistry of rubber, for very high molecular weights had been measured by the physical methods of Raoult. In other words, polymers are like chains of paper clips, at first the majority of Staudinger’s colleagues refused to accept the possibility that small molecules could link together covalently to form high-molecular weight compounds. As Mülhaupt aptly notes, this is due in part to the fact that molecular structure, in 1926 he was appointed lecturer of chemistry at the University of Freiburg at Freiburg in Breisgau, where he spent the rest of his career. In 1927, he married the Latvian botanist, Magda Voita (also shown as, further evidence to support his polymer hypothesis emerged in the 1930s. High molecular weights of polymers were confirmed by membrane osmometry, the X-ray diffraction studies of polymers by Herman Mark provided direct evidence for long chains of repeating molecular units. And the synthetic work led by Carothers demonstrated that such as nylon. His theory opened up the subject to development, and helped place polymer science on a sound basis. Staudinger’s groundbreaking elucidation of the nature of the high-molecular weight compounds he termed Makromoleküle paved the way for the birth of the field of polymer chemistry, Staudinger himself saw the potential for this science long before it was fully realized. e. Staudinger founded the first polymer chemistry journal in 1940, and in 1953 received the Nobel Prize in Chemistry for “his discoveries in the field of macromolecular chemistry. ”In 1999, heidegger and Nazism, denounced or demoted non-Nazis Polymer science Helmut Ringsdorf. Hermann Staudinger and the Future of Polymer Research Jubilees – Beloved Occasions for Cultural Piety, ogilvie, Marilyn Bailey, Harvey, Joy Dorothy
39.
Neoprene
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Neoprene or polychloroprene is a family of synthetic rubbers that are produced by polymerization of chloroprene. Neoprene exhibits good chemical stability and maintains flexibility over a temperature range. Neoprene is produced by polymerization of chloroprene. In commercial production, this polymer is prepared by free radical emulsion polymerization, polymerization is initiated using potassium persulfate. Bifunctional nucleophiles, metal oxides, and thioureas are used to crosslink individual polymer strands, outside of Russia and China, about 300,000 tons of neoprene are produced annually. After DuPont purchased the patent rights from the university, Wallace Carothers of DuPont took over development of Nieuwlands discovery in collaboration with Nieuwland himself. Arnold Collins at DuPont focused on monovinyl acetylene and allowed it to react with hydrogen chloride gas, DuPont first marketed the compound in 1931 under the trade name DuPrene, but its commercial possibilities were limited by the original manufacturing process, which left the product with a foul odor. A new process was developed, which eliminated the odor-causing byproducts and halved production costs, to prevent shoddy manufacturers from harming the products reputation, the trademark DuPrene was restricted to apply only to the material sold by DuPont. By 1939, sales of neoprene were generating profits over $300,000 for the company, Neoprene resists degradation more than natural or synthetic rubber. This relative inertness makes it suited for demanding applications such as gaskets, hoses. It can be used as a base for adhesives, noise isolation in power transformer installations and it resists burning better than exclusively hydrocarbon based rubbers, resulting in its appearance in weather stripping for fire doors and in combat related attire such as gloves and face masks. Because of its tolerance of extreme conditions, neoprene is used to line landfills, neoprenes burn point is around 260°C. Neoprene foam is used in many applications. Neoprene foam can be produced in either closed-cell or open-cell form, the closed-cell form is waterproof, less compressible and more expensive. The open-cell form can be breathable, Neoprene is used as a load bearing base, usually between two prefabricated reinforced concrete elements or steel plates as well to evenly guide force from one element to another. Neoprene is commonly used as a material for fly fishing waders, Neoprene waders are usually about 5 mm thick, and in the medium price range as compared to cheaper materials such as nylon and rubber. However, neoprene is less expensive than breathable fabrics, a foamed neoprene containing gas cells is used as an insulation material, most notably in wetsuits. Foamed neoprene is used in other insulation and shock-protection applications
40.
Great Depression
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The Great Depression was a severe worldwide economic depression that took place during the 1930s. The timing of the Great Depression varied across nations, in most countries it started in 1929 and it was the longest, deepest, and most widespread depression of the 20th century. In the 21st century, the Great Depression is commonly used as an example of how far the economy can decline. The depression originated in the United States, after a fall in stock prices that began around September 4,1929. Between 1929 and 1932, worldwide GDP fell by an estimated 15%, by comparison, worldwide GDP fell by less than 1% from 2008 to 2009 during the Great Recession. Some economies started to recover by the mid-1930s, however, in many countries, the negative effects of the Great Depression lasted until the beginning of World War II. The Great Depression had devastating effects in both rich and poor. Personal income, tax revenue, profits and prices dropped, while international trade plunged by more than 50%, unemployment in the U. S. rose to 25% and in some countries rose as high as 33%. Cities all around the world were hit hard, especially dependent on heavy industry. Construction was virtually halted in many countries, farming communities and rural areas suffered as crop prices fell by about 60%. Facing plummeting demand with few sources of jobs, areas dependent on primary sector industries such as mining and logging suffered the most. Even after the Wall Street Crash of 1929 optimism persisted for some time, john D. Rockefeller said These are days when many are discouraged. In the 93 years of my life, depressions have come, prosperity has always returned and will again. The stock market turned upward in early 1930, returning to early 1929 levels by April and this was still almost 30% below the peak of September 1929. Together, government and business spent more in the first half of 1930 than in the period of the previous year. On the other hand, consumers, many of whom had suffered losses in the stock market the previous year. In addition, beginning in the mid-1930s, a severe drought ravaged the agricultural heartland of the U. S, by mid-1930, interest rates had dropped to low levels, but expected deflation and the continuing reluctance of people to borrow meant that consumer spending and investment were depressed. By May 1930, automobile sales had declined to below the levels of 1928, prices in general began to decline, although wages held steady in 1930
41.
Chemical engineering
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A chemical engineer designs large-scale processes that convert chemicals, raw materials, living cells, microorganisms and energy into useful forms and products. A1996 British Journal for the History of Science article cites James F. Donnelly for mentioning an 1839 reference to chemical engineering in relation to the production of sulfuric acid. In the same however, George E. Davis, an English consultant, was credited for having coined the term. The History of Science in United States, An Encyclopedia puts this at around 1890, Chemical engineering, describing the use of mechanical equipment in the chemical industry, became common vocabulary in England after 1850. By 1910, the profession, chemical engineer, was already in use in Britain. Chemical engineering emerged upon the development of operations, a fundamental concept of the discipline of chemical engineering. Most authors agree that Davis invented the concept of operations if not substantially developed it. He gave a series of lectures on unit operations at the Manchester Technical School in 1887, three years before Davis lectures, Henry Edward Armstrong taught a degree course in chemical engineering at the City and Guilds of London Institute. Armstrongs course failed simply because its graduates, were not especially attractive to employers. Employers of the time would have rather hired chemists and mechanical engineers, starting from 1888, Lewis M. Norton taught at MIT the first chemical engineering course in the United States. Nortons course was contemporaneous and essentially similar with Armstrongs course, both courses, however, simply merged chemistry and engineering subjects. Its practitioners had difficulty convincing engineers that they were engineers and chemists that they were not simply chemists, unit operations was introduced into the course by William Hultz Walker in 1905. By the early 1920s, unit operations became an important aspect of engineering at MIT and other US universities. For instance, it defined chemical engineering to be a science of itself, unit operations in a 1922 report, and with which principle, it had published a list of academic institutions which offered satisfactory chemical engineering courses. Meanwhile, promoting chemical engineering as a science in Britain lead to the establishment of the Institution of Chemical Engineers in 1922. IChemE likewise helped make unit operations considered essential to the discipline, by the 1940s, it became clear that unit operations alone was insufficient in developing chemical reactors. While the predominance of unit operations in chemical engineering courses in Britain, along with other novel concepts, such process systems engineering, a second paradigm was defined. Transport phenomena gave an analytical approach to chemical engineering while PSE focused on its elements, such as control system
42.
National Historic Chemical Landmarks
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The National Historic Chemical Landmarks program was launched by the American Chemical Society in 1992 to recognize seminal achievements in the history of chemistry and related professions. The program celebrates the centrality of chemistry, bakelite, the worlds first completely synthetic plastic, developed by Leo Baekeland around 1907 Chandler Chemistry Laboratory at Lehigh University, constructed in 1884 Joseph Priestley House, U. S. S. A. Pfizer & Co. Inc. and E. R. K, mellon to conduct scientific research and train industrial researchers The R. B. Izaak Maurits Kolthoffs role in establishing the discipline of analytical chemistry at the University of Minnesota in Minneapolis. The research and professional contributions of Rachel Holloway Lloyd, the first American woman to receive a Ph. D. in chemistry, at the University of Nebraska-Lincoln where she taught. William Kellys pneumatic iron refining process, patented in 1857, at the Lyon County Public Library in Eddyville, Kentucky, lands invention of instant photography, at the former Polaroid Corporation Laboratory in Cambridge, Massachusetts. The discovery and isolation of phytochrome, a pigment in plants that controls their germination, growth. Phytochrome was isolated in 1959 at the U. S. Department of Agricultures Beltsville Area Research Center in Beltsville, willard Libbys discovery of radiocarbon dating at the University of Chicago
43.
American Chemical Society
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The American Chemical Society is a scientific society based in the United States that supports scientific inquiry in the field of chemistry. Founded in 1876 at New York University, the ACS currently has more than 158,000 members at all levels and in all fields of chemistry, chemical engineering. It is the worlds largest scientific society by membership, the ACS is a 501 non-profit organization and holds a congressional charter under Title 36 of the United States Code. Its headquarters are located in Washington, D. C. and it has a concentration of staff in Columbus. The ACS is a source of scientific information through its peer-reviewed scientific journals, national conferences. Its publications division produces 51 scholarly journals including the prestigious Journal of the American Chemical Society, the ACS holds national meetings twice a year covering the complete field of chemistry and also holds smaller conferences concentrating on specific chemical fields or geographic regions. The primary source of income of the ACS is the Chemical Abstracts Service, the organization also publishes textbooks, administers several national chemistry awards, provides grants for scientific research, and supports various educational and outreach activities. In 1874, a group of American chemists gathered at the Joseph Priestley House to mark the 100th anniversary of Priestleys discovery of oxygen. Two years later, on 6 April 1876, during a meeting of chemists at the University of the City of New York the American Chemical Society was founded, the society received its charter of incorporation from the State of New York in 1877. Charles F. Draper was a photochemist and pioneering photographer who had produced one of the first photographic portraits in 1840, chandler would later serve as president in 1881 and 1889. The Journal of the American Chemical Society was founded in 1879 to publish original chemical research and it was the first journal published by ACS and is still the societys flagship peer-reviewed publication. Chemical & Engineering News is a trade magazine that has been published by ACS since 1923. The society adopted a new constitution aimed at nationalizing the organization in 1890, in 1905, the American Chemical Society moved from New York City to Washington, D. C. ACS was reincorporated under a charter in 1937. It was granted by the U. S. Congress and signed by president Franklin D. Roosevelt, ACSs headquarters moved to its current location in downtown Washington in 1941. Divisional activities include organizing technical sessions at ACS meetings, publishing books and resources, administering awards and lectureships, as of 2016, there are 32 technical divisions of ACS. This is the largest division of the Society and it marked its 100th Anniversary in 2008. The first Chair of the Division was Edward Curtis Franklin, the Organic Division played a part in establishing Organic Syntheses, Inc. and Organic Reactions, Inc. and it maintains close ties to both organizations
Nylon 6,6 
“Making Nylon“, Bob Burk, CHEM 1000, Carleton University, Ottawa, Canada
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