The melting point of a substance is the temperature at which it changes state from solid to liquid. At the melting point the solid and liquid phase exist in equilibrium; the melting point of a substance depends on pressure and is specified at a standard pressure such as 1 atmosphere or 100 kPa. When considered as the temperature of the reverse change from liquid to solid, it is referred to as the freezing point or crystallization point; because of the ability of some substances to supercool, the freezing point is not considered as a characteristic property of a substance. When the "characteristic freezing point" of a substance is determined, in fact the actual methodology is always "the principle of observing the disappearance rather than the formation of ice", that is, the melting point. For most substances and freezing points are 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. 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 not always the same as the melting point. In the absence of nucleators water can exist as a supercooled liquid down to −48.3 °C before freezing. The chemical element with the highest melting point is tungsten, at 3,414 °C; the often-cited carbon does not melt at ambient pressure but sublimes at about 3,726.85 °C. Tantalum hafnium carbide is a refractory compound with a high melting point of 4215 K. At the other end of the scale, helium does not freeze at all at normal pressure at temperatures arbitrarily close to absolute zero. 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 and a simple magnifier. The several grains of a solid are placed in a thin glass tube and immersed in the oil bath; the oil bath is heated and with the aid of the magnifier melting of the individual crystals at a certain temperature can be observed. In large/small devices, the sample is placed in a heating block, optical detection is automated; the measurement can be made continuously with an operating process. For instance, oil refineries measure the freeze point of diesel fuel online, meaning that the sample is taken from the process and measured automatically; this allows for more frequent measurements as the sample does not have to be manually collected and taken to a remote laboratory. For refractory materials the 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, 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; this extrapolation is accomplished by using Planck's law of radiation. The constants in this equation are not known with sufficient accuracy, causing errors in the extrapolation to become larger at higher temperatures. However, standard techniques have been developed to perform this extrapolation. Consider the case of using gold as the source. In this technique, the current through the filament of the pyrometer is adjusted until the light intensity of the filament matches that of a black-body at the melting point of gold.
This establishes the primary calibration temperature and can be expressed in terms of current through the pyrometer lamp. With the same current setting, the pyrometer is sighted on another black-body at a higher temperature. An absorbing medium of known transmission is inserted between this black-body; the temperature of the black-body is adjusted until a match exists between its intensity and that of the pyrometer filament. The true higher temperature of the black-body is determined from Planck's Law; the absorbing medium is removed and the current through the filament is adjusted to match the filament intensity to that of the black-body. This establishes a second calibration point for the pyrometer; this step is repeated to carry the calibration to hi
Safety data sheet
A safety data sheet, material safety data sheet, or product safety data sheet is a document that lists information relating to occupational safety and health for the use of various substances and products. SDSs are a used system for cataloging information on chemicals, chemical compounds, chemical mixtures. SDS information may include instructions for the safe use and potential hazards associated with a particular material or product, along with spill-handling procedures. SDS formats can vary from source to source within a country depending on national requirements. A SDS for a substance is not intended for use by the general consumer, focusing instead on the hazards of working with the material in an occupational setting. There is a duty to properly label substances on the basis of physico-chemical, health or environmental risk. Labels can include hazard symbols such as the European Union standard symbols; the same product can have different formulations in different countries. The formulation and hazard of a product using a generic name may vary between manufacturers in the same country.
The Globally Harmonized System of Classification and Labelling of Chemicals contains a standard specification for safety data sheets. The SDS follows a 16 section format, internationally agreed and for substances the SDS should be followed with an Annex which contains the exposure scenarios of this particular substance; the 16 sections are: SECTION 1: Identification of the substance/mixture and of the company/undertaking 1.1. Product identifier 1.2. Relevant identified uses of the substance or mixture and uses advised against 1.3. Details of the supplier of the safety data sheet 1.4. Emergency telephone number SECTION 2: Hazards identification 2.1. Classification of the substance or mixture 2.2. Label elements 2.3. Other hazards SECTION 3: Composition/information on ingredients 3.1. Substances 3.2. Mixtures SECTION 4: First aid measures 4.1. Description of first aid measures 4.2. Most important symptoms and effects, both acute and delayed 4.3. Indication of any immediate medical attention and special treatment needed SECTION 5: Firefighting measures 5.1.
Extinguishing media 5.2. Special hazards arising from the substance or mixture 5.3. Advice for firefighters SECTION 6: Accidental release measure 6.1. Personal precautions, protective equipment and emergency procedures 6.2. Environmental precautions 6.3. Methods and material for containment and cleaning up 6.4. Reference to other sections SECTION 7: Handling and storage 7.1. Precautions for safe handling 7.2. Conditions for safe storage, including any incompatibilities 7.3. Specific end use SECTION 8: Exposure controls/personal protection 8.1. Control parameters 8.2. Exposure controls SECTION 9: Physical and chemical properties 9.1. Information on basic physical and chemical properties 9.2. Other information SECTION 10: Stability and reactivity 10.1. Reactivity 10.2. Chemical stability 10.3. Possibility of hazardous reactions 10.4. Conditions to avoid 10.5. Incompatible materials 10.6. Hazardous decomposition products SECTION 11: Toxicological information 11.1. Information on toxicological effects SECTION 12: Ecological information 12.1.
Toxicity 12.2. Persistence and degradability 12.3. Bioaccumulative potential 12.4. Mobility in soil 12.5. Results of PBT and vPvB assessment 12.6. Other adverse effects SECTION 13: Disposal considerations 13.1. Waste treatment methods SECTION 14: Transport information 14.1. UN number 14.2. UN proper shipping name 14.3. Transport hazard class 14.4. Packing group 14.5. Environmental hazards 14.6. Special precautions for user 14.7. Transport in bulk according to Annex II of MARPOL73/78 and the IBC Code SECTION 15: Regulatory information 15.1. Safety and environmental regulations/legislation specific for the substance or mixture 15.2. Chemical safety assessment SECTION 16: Other information 16.2. Date of the latest revision of the SDS In Canada, the program known as the Workplace Hazardous Materials Information System establishes the requirements for SDSs in workplaces and is administered federally by Health Canada under the Hazardous Products Act, Part II, the Controlled Products Regulations. Safety data sheets have been made an integral part of the system of Regulation No 1907/2006.
The original requirements of REACH for SDSs have been further adapted to take into account the rules for safety data sheets of the Global Harmonised System and the implementation of other elements of the GHS into EU legislation that were introduced by Regulation No 1272/2008 via an update to Annex II of REACH. The SDS must be supplied in an official language of the Member State where the substance or mixture is placed on the market, unless the Member State concerned provide otherwise; the European Chemicals Agency has published a guidance document on the compilation of safety data sheets. The German Federal Water Management Act requires that substances be evaluated for negative influence on the physical, chemical or biological characteristics of water; these are classified into numeric water hazard classes. WGK nwg: Non-water polluting substance WGK 1: Slightly water polluting substance WGK 2: Water polluting substance WGK 3: Highly water polluting substance This section contributes to a better understanding of the regulations governing SDS within the South African framework.
As regulations may change, it is the responsibility of the reader to verify the validity of the regulations mentioned in text. As globalisation increased and countries engaged in cross-border trade, the quantity of hazardous material crossing international borders a
The Jmol applet, among other abilities, offers an alternative to the Chime plug-in, no longer under active development. While Jmol has many features that Chime lacks, it does not claim to reproduce all Chime functions, most notably, the Sculpt mode. Chime requires plug-in installation and Internet Explorer 6.0 or Firefox 2.0 on Microsoft Windows, or Netscape Communicator 4.8 on Mac OS 9. Jmol operates on a wide variety of platforms. For example, Jmol is functional in Mozilla Firefox, Internet Explorer, Google Chrome, Safari. Chemistry Development Kit Comparison of software for molecular mechanics modeling Jmol extension for MediaWiki List of molecular graphics systems Molecular graphics Molecule editor Proteopedia PyMOL SAMSON Official website Wiki with listings of websites and moodles Willighagen, Egon. "Fast and Scriptable Molecular Graphics in Web Browsers without Java3D". Doi:10.1038/npre.2007.50.1
A carbohydrate is a biomolecule consisting of carbon and oxygen atoms with a hydrogen–oxygen atom ratio of 2:1 and thus with the empirical formula Cmn. This formula holds true for monosaccharides; some exceptions exist. The carbohydrates are technically hydrates of carbon; the term is most common in biochemistry, where it is a synonym of saccharide, a group that includes sugars and cellulose. The saccharides are divided into four chemical groups: monosaccharides, disaccharides and polysaccharides. Monosaccharides and disaccharides, the smallest carbohydrates, are referred to as sugars; the word saccharide comes from the Greek word σάκχαρον, meaning "sugar". While the scientific nomenclature of carbohydrates is complex, the names of the monosaccharides and disaccharides often end in the suffix -ose, as in the monosaccharides fructose and glucose and the disaccharides sucrose and lactose. Carbohydrates perform numerous roles in living organisms. Polysaccharides serve as structural components; the 5-carbon monosaccharide ribose is an important component of coenzymes and the backbone of the genetic molecule known as RNA.
The related deoxyribose is a component of DNA. Saccharides and their derivatives include many other important biomolecules that play key roles in the immune system, preventing pathogenesis, blood clotting, development, they are found in a wide variety of processed foods. Starch is a polysaccharide, it is abundant in cereals and processed food based on cereal flour, such as bread, pizza or pasta. Sugars appear in human diet as table sugar, lactose and fructose, both of which occur in honey, many fruits, some vegetables. Table sugar, milk, or honey are added to drinks and many prepared foods such as jam and cakes. Cellulose, a polysaccharide found in the cell walls of all plants, is one of the main components of insoluble dietary fiber. Although it is not digestible, insoluble dietary fiber helps to maintain a healthy digestive system by easing defecation. Other polysaccharides contained in dietary fiber include resistant starch and inulin, which feed some bacteria in the microbiota of the large intestine, are metabolized by these bacteria to yield short-chain fatty acids.
In scientific literature, the term "carbohydrate" has many synonyms, like "sugar", "saccharide", "ose", "glucide", "hydrate of carbon" or "polyhydroxy compounds with aldehyde or ketone". Some of these terms, specially "carbohydrate" and "sugar", are used with other meanings. In food science and in many informal contexts, the term "carbohydrate" means any food, rich in the complex carbohydrate starch or simple carbohydrates, such as sugar. In lists of nutritional information, such as the USDA National Nutrient Database, the term "carbohydrate" is used for everything other than water, fat and ethanol; this includes chemical compounds such as acetic or lactic acid, which are not considered carbohydrates. It includes dietary fiber, a carbohydrate but which does not contribute much in the way of food energy though it is included in the calculation of total food energy just as though it were a sugar. In the strict sense, "sugar" is applied for sweet, soluble carbohydrates, many of which are used in food.
The name "carbohydrate" was used in chemistry for any compound with the formula Cm n. Following this definition, some chemists considered formaldehyde to be the simplest carbohydrate, while others claimed that title for glycolaldehyde. Today, the term is understood in the biochemistry sense, which excludes compounds with only one or two carbons and includes many biological carbohydrates which deviate from this formula. For example, while the above representative formulas would seem to capture the known carbohydrates and abundant carbohydrates deviate from this. For example, carbohydrates display chemical groups such as: N-acetyl, carboxylic acid and deoxy modifications. Natural saccharides are built of simple carbohydrates called monosaccharides with general formula n where n is three or more. A typical monosaccharide has the structure H–x–y–H, that is, an aldehyde or ketone with many hydroxyl groups added one on each carbon atom, not part of the aldehyde or ketone functional group. Examples of monosaccharides are glucose and glyceraldehydes.
However, some biological substances called "monosaccharides" do not conform to this formula and there are many chemicals that do conform to this formula but are not considered to be monosaccharides. The open-chain form of a monosaccharide coexists with a closed ring form where the aldehyde/ketone carbonyl group carbon and hydroxyl group react forming a hemiacetal with a new C–O–C bridge. Monosaccharides can be linked togeth
Procter & Gamble
The Procter & Gamble Company is an American multi-national consumer goods corporation headquartered in downtown Cincinnati, founded in 1837 by English American William Procter and Irish American James Gamble. It specializes in a wide range of personal health/consumer health, personal care and hygiene products. Before the sale of Pringles to the Kellogg Company, its product portfolio included foods and beverages. In 2014, P&G recorded $83.1 billion in sales. On August 1, 2014, P&G announced it was streamlining the company and selling off around 100 brands from its product portfolio in order to focus on the remaining 65 brands, which produced 95% of the company's profits. A. G. Lafley—the company's chairman, CEO until October 31, 2015—said the future P&G would be "a much simpler, much less complex company of leading brands that's easier to manage and operate". David Taylor is the current CEO of Procter & Gamble. Candlemaker William Procter, born in England, soapmaker James Gamble, born in Ireland, both emigrated from the United Kingdom.
They settled in Cincinnati and met when they married sisters Olivia and Elizabeth Norris. Alexander Norris, their father-in-law, called a meeting in which he persuaded his new sons-in-law to become business partners. On October 31, 1837, as a result of the suggestion, Procter & Gamble was created. In 1858–1859, sales reached $1 million. By that point, about 80 employees worked for Gamble. During the American Civil War, the company won contracts to supply the Union Army with soap and candles. In addition to the increased profits experienced during the war, the military contracts introduced soldiers from all over the country to Procter & Gamble's products. In the 1880s, Procter & Gamble began to market a new product, an inexpensive soap that floats in water; the company called the soap Ivory. William Arnett Procter, William Procter's grandson, began a profit-sharing program for the company's workforce in 1887. By giving the workers a stake in the company, he assumed that they would be less to go on strike.
The company began to build factories in other locations in the United States because the demand for products had outgrown the capacity of the Cincinnati facilities. The company's leaders began to diversify its products, as well, in 1911, began producing Crisco, a shortening made of vegetable oils rather than animal fats; as radio became more popular in the 1920s and 1930s, the company sponsored a number of radio programs. As a result, these shows became known as "soap operas"; the company moved into other countries, both in terms of manufacturing and product sales, becoming an international corporation with its 1930 acquisition of the Thomas Hedley Co. based in Newcastle upon Tyne, England. After this acquisition, Procter & Gamble had their UK Headquarters at'Hedley House' in Newcastle upon Tyne, until quite recently. Numerous new products and brand names were introduced over time, Procter & Gamble began branching out into new areas; the company introduced Tide laundry detergent in 1946 and Prell shampoo in 1947.
In 1955, Procter & Gamble began selling the first toothpaste to contain fluoride, known as Crest. Branching out once again in 1957, the company purchased Charmin paper mills and began manufacturing toilet paper and other tissue paper products. Once again focusing on laundry, Procter & Gamble began making Downy fabric softener in 1960 and Bounce fabric softener sheets in 1972. One of the most revolutionary products to come out on the market was the company's disposable Pampers diaper, first test-marketed in 1961, the same year Procter & Gamble came out with Head & Shoulders. Prior to this point, disposable diapers were not popular, although Johnson & Johnson had developed a product called Chux. Babies always wore cloth diapers, which were labor-intensive to wash. Pampers provided a convenient alternative, albeit at the environmental cost of more waste requiring landfilling. Amid the recent concerns parents have voiced on the ingredients in diapers, Pampers launch Pampers Pure collection in 2018, a "natural" diaper alternative.
Procter & Gamble acquired a number of other companies that diversified its product line and increased profits. These acquisitions included Folgers Coffee, Norwich Eaton Pharmaceuticals, Richardson-Vicks, Shulton's Old Spice, Max Factor, the Iams Company, Pantene, among others. In 1994, the company made headlines for big losses resulting from levered positions in interest rate derivatives, subsequently sued Bankers Trust for fraud. In 1996, P&G again made headlines when the Food and Drug Administration approved a new product developed by the company, Olestra. Known by its brand name'Olean', Olestra is a lower-calorie substitute for fat in cooking potato chips and other snacks. In January 2005, P&G announced the acquisition of Gillette, forming the largest consumer goods company and placing Unilever into second place; this added brands such as Gillette razors, Duracell and Oral-B to their stable. The acquisition was approved by the European Union and the Federal Trade Commission, with conditions to a spinoff of certain overlapping brands.
P&G agreed to sell its SpinBrush battery-operated electric toothbrush business to Church & Dwight, Gillette's Rembrandt toothpaste line to Johnson & Johnson. The deodorant brands Right Guard and Dri, Dry Idea were sold to Dial Corporation; the compa
Hydroxyapatite called hydroxylapatite, is a occurring mineral form of calcium apatite with the formula Ca53, but it is written Ca1062 to denote that the crystal unit cell comprises two entities. Hydroxyapatite is the hydroxyl endmember of the complex apatite group; the OH− ion can be replaced by fluoride, chloride or carbonate, producing fluorapatite or chlorapatite. It crystallizes in the hexagonal crystal system. Pure hydroxyapatite powder is white. Occurring apatites can, however have brown, yellow, or green colorations, comparable to the discolorations of dental fluorosis. Up to 50% by volume and 70% by weight of human bone is a modified form of hydroxyapatite, known as bone mineral. Carbonated calcium-deficient hydroxyapatite is the main mineral of which dental enamel and dentin are composed. Hydroxyapatite crystals are found in the small calcifications, within the pineal gland and other structures, known as corpora arenacea or'brain sand'. Hydroxyapatite can be synthesized via several methods, such as wet chemical deposition, biomimetic deposition, sol-gel route or electrodeposition.
Yagai and Aoki proposed the hydroxyapatite nanocrystal suspension can be prepared by a wet chemical precipitation reaction following the reaction equation below:10 Ca2 + 6 H3PO4 → Ca1062 + 18 H2O Several studies have shown that hydroxyapatite synthesis via the wet-chemical route can be improved by high-power ultrasound. The ultrasonically assisted synthesis of hydroxyapatite is a successful technique for the production of nanostructured hydroxyapatite to high quality standards; the ultrasonic route allows the production of nano-crystalline hydroxyapatite as well as modified particles, e.g. core-shell nanospheres and composites. Calcium deficient hydroxyapatite, Ca10−x6−xx2−x has a Ca/P ratio between 1.67 and 1.5. The Ca/P ratio is used in the discussion of calcium phosphate phases. Stoichiometric apatite Ca1062 has a Ca/P ratio of 10:6 expressed as 1.67. The non-stoichiometric phases have the hydroxyapatite structure with cation vacancies and anion vacancies; the sites occupied by phosphate anions in stochiometric hydroxyapatite, are occupied by phosphate or hydrogen phosphate, HPO42–, anions.
Preparation of these calcium deficient phases can be prepared by precipitation from a mixture of calcium nitrate and diammonium phosphate with the desired Ca/P ratio, for example to make a sample with a Ca/P ratio of 1.6: 9.6 Ca2 + 6 2HPO4 → Ca220.127.116.11.6Sintering these non-stoichiometric phases forms a solid phase, an intimate mixture of tricalcium phosphate and hydroxyapatite, termed biphasic calcium phosphate: Ca10−x6−xx2−x → Ca1062 + 3x Ca32 The clubbing appendages of the Odontodactylus scyllarus are made of an dense form of the mineral which has a higher specific strength and toughness than any synthetic composite material. Their dactyl appendages have excellent impact resistance due to the impact region being composed of crystalline hydroxyapatite, which offers significant hardness. A periodic layer underneath the impact layer composed of hydroxyapatite with lower calcium and phosphorus content inhibits crack growth by forcing new cracks to change directions; this periodic layer reduces the energy transferred across both layers due to the large difference in modulus reflecting some of the incident energy.
Hydroxyapatite is present in bone and teeth. HA is 70 to 80% of the mass of dentin and enamel in teeth. In enamel, the matrix for HA is formed by enamelins instead of collagen. Hydroxylapatite deposits in tendons around joints results in the medical condition calcific tendinitis. HA is used to make bone grafting materials as well as dental prosthetics and repair; some implants, e.g. hip replacements, dental implants and bone conduction implants, are coated with HA.. As the native dissolution rate of hydroxyapatite in-vivo, around 10 wt% per year, is lower than the growth rate of newly formed bone tissue, in its use as a bone replacement material, ways are being sought to enhance its solubility rate and thus promote better bioactivity. Microcrystalline hydroxyapatite is marketed as a "bone-building" supplement with superior absorption in comparison to calcium, it is a second-generation calcium supplement derived from bovine bone. In the 1980s, bone meal calcium supplements were found to be contaminated with heavy metals, although the manufacturers claim their MH is free from contaminants, it isn't recommended because its effect in the body has not been well-tested.
The mechanism of hydroxyapatite chromatography is complicated and has been described as "mixed-mode" ion exchange. It involves nonspecific interactions between positively charged calcium ions and negatively charged phosphate ions on the stationary phase HA resin with protein negatively charged carboxyl groups and positively charged amino groups, it may be difficult to predict the effectiveness of HA chromatography based on physical and chemical properties of the desired protein to be purified. For elution, a buffer with increasing phosphate concentration is used for application. In archaeology, hydroxyapatite from human and animal remains can be analysed to reconstruct ancient diets and palaeoclimate; the mineral fractions of bone and teeth act as a reserv
Colgate is an umbrella brand principally used for oral hygiene products such as toothpastes, toothbrushes and dental floss. Manufactured by the American consumer-goods conglomerate Colgate-Palmolive, Colgate oral hygiene products were first sold by the company in 1873, sixteen years after the death of the founder, William Colgate; the company sold soap. According to a 2015 report by market research company Kantar Worldpanel, Colgate is the only brand in the world purchased by more than half of all households. Colgate has a global market penetration of 67.7% and a global market share of 45%. Despite this, it maintained the highest growth rate of all brands in the survey, with 40 million new households purchasing Colgate-branded products in 2014, its global market penetration is nearly 50%. Colgate was the first toothpaste in a collapsible tube, introduced in 1896 in New York City, it had been sold in glass jars since 1873. It has been in Malaysia since the 1920s, it is with manufacturing units based in India and exported to Nepal.
While in the Philippines, it was introduced in 1926 under The Palmolive Company Philippines before it changed its name to Colgate-Palmolive Philippines in 1949. In 1957, Colgate established its first factory in India to produce toothpaste for the domestic market, by 1999 became the highest selling brand in the world. Colgate products are marketed in China under its Chinese Brand name 高露洁, which means "high-quality cleaning gel"; as of 2002, Colgate occupied 20% of the market share for toothpastes in China. As of 2015, it commanded 70% of the oral care market in Brazil. In 2007, the Advertising Standards Authority in the UK told Colgate that it could no longer make the claim that 4 out of 5 dentists recommended Colgate. Investigation had showed that the study had telephone surveyed dentists to list toothpastes they recommended, their competitors were recommended at similar rates; the claim was deemed deceptive. As of 2015, oral care products were the Colgate-Palmolive company's largest source of income, making up around US$7.5 billion, or 47% of net sales globally.
List of toothpaste brands Index of oral health and dental articles Official website