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BPA Controversy
Bisphenol A controversy centers on concerns and debates about the biomedical significance of bisphenol A (BPA), which is a precursor to polymers that are used in some consumer products, including some food containers. The concerns began with the hypothesis that BPA is an endocrine disruptor, i.e. it mimics endocrine hormones and thus has the unintended and possibly far-reaching effects on people in physical contact with the chemical. Since 2008, several governments have investigated its safety, which prompted some retailers to withdraw polycarbonate products. The U.S. Food and Drug Administration (FDA) ended its authorization of the use of BPA in baby bottles and infant formula packaging, based on market abandonment, not safety. The European Union and Canada have banned BPA use in baby bottles. The U.S. FDA states "BPA is safe at the current levels occurring in foods" based on extensive research, including two more studies issued by the agency in early 2014. The European Foo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polyether
In organic chemistry, ethers are a class of compounds that contain an ether group—an oxygen atom connected to two alkyl or aryl groups. They have the general formula , where R and R′ represent the alkyl or aryl groups. Ethers can again be classified into two varieties: if the alkyl or aryl groups are the same on both sides of the oxygen atom, then it is a simple or symmetrical ether, whereas if they are different, the ethers are called mixed or unsymmetrical ethers. A typical example of the first group is the solvent and anaesthetic diethyl ether, commonly referred to simply as "ether" (). Ethers are common in organic chemistry and even more prevalent in biochemistry, as they are common linkages in carbohydrates and lignin. Structure and bonding Ethers feature bent C–O–C linkages. In dimethyl ether, the bond angle is 111° and C–O distances are 141 pm. The barrier to rotation about the C–O bonds is low. The bonding of oxygen in ethers, alcohols, and water is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diethylstilbestrol
Diethylstilbestrol (DES), also known as stilbestrol or stilboestrol, is a nonsteroidal estrogen medication, which is presently rarely used. In the past, it was widely used for a variety of indications, including pregnancy support for those with a history of recurrent miscarriage, hormone therapy for menopausal symptoms and estrogen deficiency, treatment of prostate cancer and breast cancer, and other uses. By 2007, it was only used in the treatment of prostate cancer and breast cancer. In 2011, Hoover and colleagues reported on adverse health outcomes linked to DES including infertility, miscarriage, ectopic pregnancy, preeclampsia, preterm birth, stillbirth, infant death, menopause prior to age 45, breast cancer, cervical cancer, and vaginal cancer. While most commonly taken by mouth, DES was available for use by other routes as well, for instance, vaginal, topical, and by injection. DES is an estrogen, or an agonist of the estrogen receptors, the biological target of estroge ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Charles Dodds
Sir Edward Charles Dodds, 1st Baronet (13 October 1899 – 16 December 1973) was a British biochemist. Personal life He was born in Liverpool in 1899, the only child of Ralph Edward Dodds, a shoe retailer, and Jane (née Pack) Dodds. The family shortly moved to Leeds, then to Darlington and then to Chesham, Bucks, where he attended Harrow County School. From there he entered the Middlesex Hospital Medical School in London in 1916, spent one year in the army in 1917, and qualified MRCS and LRCP in 1921. He died at Sussex Square in Paddington, London on 16 December 1973. Career In 1924 he was appointed to the new Chair of Biochemistry at the University of London which was started in the Bland Sutton Institute of Pathology at the Middlesex. Three years later, he was appointed Director of the recently completed Courtauld Institute of Biochemistry and retained these two appointments until his retirement forty years later. His scientific interests were wide and varied; he had a conti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gutta Percha
Gutta-percha is a tree of the genus ''Palaquium'' in the family Sapotaceae. The name also refers to the rigid, naturally biologically inert, resilient, electrically nonconductive, thermoplastic latex derived from the tree, particularly from ''Palaquium gutta''; it is a polymer of isoprene which forms a rubber-like elastomer. The word "gutta-percha" comes from the plant's name in Malay: ''getah'' translates as "latex". ''Percha'' or ''perca'' is an older name for Sumatra. Description ''P. gutta'' trees are tall and up to in trunk diameter. The leaves are evergreen, alternate or spirally arranged, simple, entire, long, glossy green above, and often yellow or glaucous below. The flowers are produced in small clusters along the stems, each flower with a white corolla with four to seven (mostly six) acute lobes. The fruit is an ovoid berry, containing one to four seeds; in many species, the fruit is edible. In Australia, gutta-percha is a common name specifically used for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Epoxy
Epoxy is the family of basic components or cured end products of epoxy resins. Epoxy resins, also known as polyepoxides, are a class of reactive prepolymers and polymers which contain epoxide groups. The epoxide functional group is also collectively called ''epoxy''. The IUPAC name for an epoxide group is an oxirane. Epoxy resins may be reacted (cross-linked) either with themselves through catalytic homopolymerisation, or with a wide range of co-reactants including polyfunctional amines, acids (and acid anhydrides), phenols, alcohols and thiols (usually called mercaptans). These co-reactants are often referred to as hardeners or curatives, and the cross-linking reaction is commonly referred to as curing. Reaction of polyepoxides with themselves or with polyfunctional hardeners forms a thermosetting polymer, often with favorable mechanical properties and high thermal and chemical resistance. Epoxy has a wide range of applications, including metal coatings, composites, use in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Point Of Sale
The point of sale (POS) or point of purchase (POP) is the time and place at which a retail transaction is completed. At the point of sale, the merchant calculates the amount owed by the customer, indicates that amount, may prepare an invoice for the customer (which may be a cash register printout), and indicates the options for the customer to make payment. It is also the point at which a customer makes a payment to the merchant in exchange for goods or after provision of a service. After receiving payment, the merchant may issue a receipt for the transaction, which is usually printed but can also be dispensed with or sent electronically. To calculate the amount owed by a customer, the merchant may use various devices such as weighing scales, barcode scanners, and cash registers (or the more advanced "POS cash registers", which are sometimes also called "POS systems"). To make a payment, payment terminals, touch screens, and other hardware and software options are available. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carbonless Copy Paper
Carbonless copy paper (CCP), non-carbon copy paper, or NCR paper (No Carbon Required, taken from the initials of its creator, National Cash Register) is a type of coated paper designed to transfer information written on the front onto sheets beneath. It was developed by chemists Lowell Schleicher and Barry Green, as an alternative to carbon paper and is sometimes misidentified as such. Carbonless copying provides an alternative to the use of carbon copying. Carbonless copy paper has micro-encapsulated dye or ink on the back side of the top sheet, and a clay coating on the front side of the bottom sheet. When pressure is applied (from writing or impact printing), the dye capsules rupture and react with the clay to duplicate the markings made to the top sheet. Intermediary sheets, with clay on the front and dye capsules on the back, can be used to create multiple copies; this may be referred to as multipart stationery. Operation Carbonless copy paper consists of sheets of paper th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PET Film (biaxially Oriented)
BoPET (biaxially-oriented polyethylene terephthalate) is a polyester film made from stretched polyethylene terephthalate (PET) and is used for its high tensile strength, chemical and dimensional stability, transparency, reflectivity, gas and aroma barrier properties, and electrical insulation. A variety of companies manufacture boPET and other polyester films under different brand names. In the UK and US, the best-known trade names are Mylar, Melinex, and Hostaphan. History BoPET film was developed in the mid-1950s,Izard, Emmette Farr"Production of polyethylene terephthalate" U.S. patent no. 2,534,028 (filed: 1948 May 13; issued: 1950 December 12). originally by DuPont, Imperial Chemical Industries (ICI), and Hoechst. In 1955 Eastman Kodak used Mylar as a support for photographic film and called it "ESTAR Base". The very thin and tough film allowed reels to be exposed on long-range U-2 reconnaissance flights. In 1964, NASA launched Echo II, a diameter balloon constructed ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Beverage Can
A drink can (or beverage can) is a metal container designed to hold a fixed portion of liquid such as carbonated soft drinks, alcoholic drinks, fruit juices, teas, herbal teas, energy drinks, etc. Drink cans are made of aluminum (75% of worldwide production) or tin-plated steel (25% worldwide production). Worldwide production for all drink cans is approximately 370 billion cans per year. History The first commercial beer available in cans began in 1935 in Richmond, Virginia. Not long after that, sodas, with their higher acidity and somewhat higher pressures, were available in cans. The key development for storing drinks in cans was the interior liner, typically plastic or sometimes a waxy substance, that helped to keep the product's flavor from being ruined by a chemical reaction with the metal. Another major factor for the timing was the repeal of Prohibition in the United States at the end of 1933. In 1935, the Felinfoel Brewery at Felinfoel in Wales was the first bre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polymerization
In polymer chemistry, polymerization (American English), or polymerisation (British English), is a process of reacting monomer, monomer molecules together in a chemical reaction to form polymer chains or three-dimensional networks. There are many forms of polymerization and different systems exist to categorize them. In chemical compounds, polymerization can occur via a variety of reaction mechanisms that vary in complexity due to the functional groups present in the reactants and their inherent steric effects. In more straightforward polymerizations, alkenes form polymers through relatively simple free-radical reaction, radical reactions; in contrast, reactions involving substitution at a carbonyl group require more complex synthesis due to the way in which reactants polymerize. Alkanes can also be polymerized, but only with the help of strong acids. As alkenes can polymerize in somewhat straightforward radical reactions, they form useful compounds such as polyethylene and p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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