bluuebunny/crossref_metadata_2025_split huggingface dataset:
Gemstone Materials
Authors: Nassau Kurt 
Published: July 2004

AbstractThere are three types of gemstone materials as defined by the U.S. Federal Trade Commission: natural gemstones are found in nature and at most are enhanced; imitation or simulated, fake, faux, etc, material resembles the natural material in appearance only and is frequently only colored glass or even plastic; and synthetic material is the exact duplicate of the natural material, having the same chemical composition, optical properties, etc, as the natural, but made in the laboratory. The word gem cannot be used for synthetic gemstone material. The synthetic equivalent of a natural material may be used as an imitation of another. Synthetic gemstone materials often have multiple uses. Synthetic ruby and colorless sapphire are used for watch bearings, unscratchable watch crystals, and bar‐code reader windows. Synthetic quartz oscillators are used for precision timekeeping, citizen's band radio (CB) crystals, and filters. Synthetic ruby, emerald, and garnets are used for masers and lasers. In the gemstone jewelry market, synthetics provide a less expensive alternative to natural gemstones, but of a better quality than that available in costume jewelry. In general, a synthetic should be available for no more than 10% of the cost of equivalent‐quality natural gemstone to be commercially viable. The important properties are those of importance in natural gemstones. Several gemstone species occur in various colors, depending on the presence of impurities or irradiation‐induced color centers.The most frequently used techniques for the commercial manufacture of synthetic gemstone materials are based on crystal growth from the meet or crystal growth from solution.
Glass
Authors: Boyd David C. , Danielson Paul S. , Thompson David A. , Velez Mariano , Reis Signo T. , Brow Richard K. 
Published: July 2004

AbstractBoth organic and inorganic materials may form glasses if their structure is noncrystalline, ie, if they lack long‐range order. This includes some plastics, metals, and organic liquids. In principle, rapid cooling could prevent crystallization of any substance if the final temperature is sufficiently low to prevent structural rearrangement. Thus glasses are formed primarily for kinetic reasons.Glasses can be prepared by methods other than cooling from a liquid state, including from solid/crystalline state and vapor phases by ultrafast grinding procedure.Conditions favorable for glass formation may be deduced from either geometric or bond strength considerations. Glass formation of individual oxides can be predicted from the melting point, and individual bond energies can be normalized by dividing by the melting point of the oxide. Glass is a good medium for controlled crystallization, and has become the basis for a number of unique crystalline materials known as glass‐ceramics. Glass manufacture requires four major stages: batch preparation, meltings and refining, forming, and post‐forming.Most glass articles are manufactured by a process in which raw materials are converted at high temperatures to a homogeneous melt that is then formed into the articles. Molten glass is either molded, drawn, rolled, or quenched, depending on desired shape and use.Glass has lost to market share to aluminum and plastic for containers. Glass recycling, however, benefits the manufacturer and help shrink the high cost of waste disposal.Glass is used in architecture, beverage containers, and insulation. Newer uses such as components in batteries, switches, glass‐ceramics, sol–gel glasses are discussed.
Glasses, Organic–;Inorganic Hybrids
Authors: Brennan A. B. , Miller T. M. 
Published: July 2004

Abstract
The search for new high performance materials has spurred the development of composites combining high modulus/high thermal stability inorganic glasses and low modulus/low thermal stability polymeric glasses. Research has resulted in a novel class of amorphous polymer–glass composites referred to as organic–inorganic hybrids or inorganic–organic hybrids, depending on the component with the highest volume fraction. These materials are synthesized in a variety of ways but ultimately exhibit near‐molecular‐level mixing of the matrix and the filler. Hence the term hybrid. Typically, this high degree of mixing results in transparent materials which exhibit significant increases in thermomechanical properties owing to extensive interaction between the polymeric and inorganic phases. However, the relatively high volume fraction of polymer included in these materials normally limits their service temperatures to well below 400°C. Many polymers and oligomers have been utilized in the synthesis of these hybrids, including poly(alkenes, acrylates, ethers, esters, amides, imides, and dienes). Some novel inorganic precursors have been used, such as clay. The use of metal alkoxides have been reported.
There are several areas of application for organic–inorganic hybrids: microelectronic usage, abrasion‐resistant coatings, thermal–oxidative‐resistant coatings, nonlinear optical devices, hydrogels, biosensors, and cross‐linking agents.
Glass‐Ceramics
Authors: Pinckney Linda R. 
Published: July 2004

AbstractAs materials formed by the controlled nucleation and crystallization of glass, glass‐ceramics can combine the advantages of glass with the optical and mechanical benefits of crystals. Commercial glass‐ceramics are used in applications requiring high thermal and mechanical stability, with products including radiant cooktop panels, telescope mirrors, cookware, and dental and medical prostheses. In addition to these products, future applications for glass‐ceramics are likely to capitalize on designed‐in, highly specialized properties for the transmission, display, and storage of information.
Recycling, Glass
Authors: Ross C. Pp 
Published: July 2004

Abstract
Ross, C. Philip (Creative Opportunities, Inc.). The properties of glass provide attributes for many commercial products. As some of these products reach the end of their useful life and are discarded, there is the opportunity to have the material recycled into other useful products. This alternative is preferred over having the material enter a municipal waste stream for landfill disposal. Glass can be remelted and refabricated over and over again without any deterioration of the material properties. Limitations for recycling of glass involve the level of contamination from other categories or colors of glass, as well as from a variety of nonglass materials. For successful recycling, glass must be processed in a manner consistent with the requirements of the glass manufacturing industry. Vol. 20, pp. 1127–1134, 10 refs. to April 1995.
Glycopeptides (Dalbaheptides)
Authors: Cavalleri B. , Parenti F. 
Published: July 2004

AbstractThe vancomycin–ristocetin family of glycopeptides is a subclass of linear sugar‐containing peptides composed of seven amino acids cross‐linked to generate a specific stereochemical configuration. This configuration forms the basis of a particular mechanism of action, eg, complexation with theD‐alanyl‐D‐alanine terminus of bacterial cell wall components. The term dalbaheptide, fromD‐al (anyl‐D‐alanine)b(inding)a(ntibiotics) having hept(apept)ide structure, has been proposed to distinguish them within the larger and diverse groups of glycopeptide antibiotics. About 40 different naturally produced dalbaheptides have been reported. Among them, vancomycin and teicoplanin are used clinically as a result of high activity against gram‐positive pathogens such as many coagulase‐negativeStaphylococci(CNS), corynebacteria,Clostridium difficile, multiresistantStaphylococcus aureus, and highly gentamicin‐resistantEnterococciwhich are refractory to established drugs. Eremomycin is under clinical evaluation. Many patents claim feed‐utilization efficiency increase and growth promotion in domestic animals for several dalbaheptides but only avoparcin (Avotan) is commercially used. Knowledge of the mechanism of action and investigations on the physicochemical characteristics has stimulated the transformation of natural antibiotics into new dalbaheptide derivatives using both chemical and biosynthetic modification. All the dalbaheptides are produced by strains belonging to the order ofActinomycetales. Dalbaheptides are produced by submerged fermentation. Pure dalbaheptides are obtained as colorless or whitish amorphous powders that usually retain water and solvents. Dalbaheptides are generally water‐soluble. Teicoplanin can be obtained as an internal salt or as a partial monoalkaline (sodium) salt. Other dalbaheptides are obtained as acidic salts. Dalbaheptides are levorotatory. The basis of the antibacterial action of dalbaheptides is the ability to form a complex with the terminalD‐Ala‐D‐Ala residues of growing peptidoglycan chains, thus preventing transglycosylation, eg, chain elongation, and transpeptidation, eg, cross‐linking. The consequent defective cell wall stops bacterial growth and eventually leads to cell death. Only three dalbaheptides are commercialized: vancomycin and teicoplanin for human health, and avoparcin for animal usage. Vancomycin and teicoplanin as formulated drugs are lyophilized powders to be reconstituted with sterile water for injection.
Glycerol
Authors: Morrison Lowen R. 
Published: July 2004

Abstract
Glycerol, a trihydric alcohol, is a clear, water‐white, viscous, sweet‐tasting hygroscopic liquid at ordinary room temperatures above its melting point. Glycerol occurs naturally in combined form as glycerides in all animal and vegetable fats and oils, and is recovered as a by‐product when these oils are saponified in the process of manufacturing soap, when the fats are split in the production of fatty acids, or when fats are esterified with methanol in the production of methyl esters. Since 1949 it has also been produced commercially by synthesis from propylene.
The uses of glycerol number in the thousands, with large amounts going into the manufacture of drugs, cosmetics, toothpastes, urethane foam, synthetic resins, and ester gums. Tobacco processing and foods also consume large amounts either as glycerol or glycerides.
Glycerol, is generally recognized as safe (GRAS) as a miscellaneous or general‐purpose food additive and it is permitted in certain food packaging materials. Glycerol derivatives include acetals, amines, esters, and ethers. Glyceryl trinitrate (nitroglycerin) is used in explosives and as a heart stimulant. Included among the esters also are the ester gums and, mono‐ and diglycerides used as emulsifiers and in shortenings. The salts of glycerophosphoric acid are used medicinally.
Gold and Gold Compounds
Authors: Cohn J.G. , Stern Eric W. , Etris Samuel F. 
Published: July 2004

AbstractGold is found as a relatively pure solid on the surface of the earth. It is widely distributed, but in very small concentrations. Gold is the most noble of the noble metals. Gold's properties are listed. The recovery of gold from ore is by the cyanidation process.Specifications and requirements of the international trading markets are discussed as well as precautions aganist fraud. Gold is very recyclable because of its value. Gold is benign to the enviornment, but the chemicals used in its mining are not. Gold is used in electronics, jewelery, coins, decoration, dentistry and medicine.
Grignard Reactions
Authors: Silverman Gary S. , Rakita Philip E. 
Published: July 2004

AbstractThe termGrignard reactionrefers to both the preparation of a class of organomagnesium halide compounds and their subsequent reaction with a wide variety of organic and inorganic substrates.The general sequence of the reactions is now embodied in the following generic forms, where RX = an organic halide (most typically a chloride or bromide, although fluorides can be induced to react); S = a coordinating solvent (such as an ether or an amine); and AZ = a substrate with an electronegative group, Z: RX + Mg +nS → RMgX·SnRMgX·Sn+ AZ → RAZMgX·SnRAZMgX·Sn→ RA + ZMgX·Sn.The development of improved industrial procedures, including the substitution of tetrahydrofuran (THF) for diethyl ether and the demonstration that the less reactive, but significantly less expensive, vinyl and aryl chlorides could be successfully used, has greatly expanded the commercial possibilities of this reaction. In the flavor, fragrance, pharmaceutical, and fine chemical industries, its use can generally be regarded as routine.The great value of the Grignard reaction to the synthetic chemist is its general applicability as a building block for an impressive range of structures and functional groups.Preparation of Grignard ReagentsA Grignard reagent is prepared by first adding magnesium and a partial charge of solvent to the reactor, followed by the addition of RX, in the remaining solvent, to the reaction flask.In spite of its industrial use for many years, the commercial‐scale production of Grignard reagents has not been extensively described.The Grignard reaction has been commercially important for a number of years, and for certain industrial processes it remains the favored (or only) practical route to construct various element‐to‐carbon bonds.There are five components to the cost of using a Grignard reagent:(1)magnesium metal,(2)the halide,(3)the solvent,(4)the substrate, and(5)disposal of the by‐products.Reactions and applications of Grignard reagents include asymmetric syntheses using Grignard reagents, Grignard reactions with inorganic chlorides, Grignard reagents as bases, metal‐assisted modified Grignard reactions, intramolecular Grignard reactions, Grignards as methacrylate polymerization catalysts, and Grignard reagents as supports for the Ziegler‐Natta process.
Halogen Fluorides
Authors: Bailey Webb I. , Woytek Andrew J. 
Published: July 2004

AbstractThere are eight known halogen fluorides, binary compounds of fluorine with chlorine, bromine, and iodine. The halogen fluorides are highly reactive, powerful oxidizing agents that exist as noncryogenic liquids, offering a storable liquid source of fluorine at low pressure. Properties are described.Chlorine trifluoride, bromine trifluoride, and iodine pentafluoride are available commercially. Chlorine trifluoride is used in the processing of nuclear fuels, bromine trifluoride as a chemical cutting agent for oil well pipe and tubing, and iodine pentafluoride as a fluorinating agent for organic compounds.
Acetic Acid, Halogenated Derivatives
Authors: Morris Earl D. , Bost John C. 
Published: July 2004

AbstractThe most important of the halogenated derivatives of acetic acid is chloroacetic acid, which has wide applications as an industrial chemical intermediate in the manufacture of cellulose ethers, herbicides, and thioglycolic acid. Most chloroacetic acid is produced by the chlorination of acetic acid. Chloroacetic acid is extremely corrosive and will cause serious chemical burns. It is readily absorbed through the skin; contamination of 5–10% of the skin is usually fatal. Sodium chloroacetate, C2H2ClO2Na, is produced by reaction of chloroacetic acid with sodium hydroxide or sodium carbonate. Dichloroacetic acid, C2H2Cl2O2, is a reactive intermediate in organic synthesis. It has been manufactured by the chlorination of acetic and chloroacetic acids and by other means. Trichloroacetic acid, C2HCl3O2, forms white deliquescent crystals. Sodium trichloroacetate, C2Cl3O2Na, is used as a herbicide. Chloroacetyl chloride (ClCH2COCl) is the corresponding acid chloride of chloroacetic acid, and is manufactured by reaction of chloroacetic acid with chlorinating agents. Much of the chloroacetyl chloride produced is used captively as a reactive intermediate. It is useful in many acylation reactions and in the production of adrenalin, diazepam, and chloroacetic anhydride. Two chloroacetate esters of industrial importance are methyl chloroacetate, C3H5ClO2, and ethyl chloroacetate, C4H7ClO2. Both are used as agricultural and pharmaceutical intermediates. Other derivatives are bromoacetic acid, dibromoacetic acid, tribromoacetic acid, iodoacetic acid, diiodoacetic acid, and triiodoacetic acid.
Flame Retardants, Halogenated
Authors: Pettigrew Alex 
Published: July 2004

AbstractHalogenated, brominated, and chlorinated organic flame retardants are widely used to reduce the flammability or ignitability of plastics; this use is growing because of increasingly strict flammability regulations. Brominated and chlorinated aliphatic and brominated aromatic compounds are used as additives to both thermoset and thermoplastic polymers. Brominated aliphatic, brominated aromatic, and chlorinated aromatic compounds are used as reactive flame retardants in both thermoset and thermoplastic polymers. In many applications, antimony oxide is used as a synergist, interacting with halogenated flame retardants to produce a more effective system. The largest volume brominated flame retardants are the brominated aromatics tetrabromobisphenol A and decarbromodiphenyl oxide. The largest volume chlorinated flame retardants are the chlorinated paraffins. The toxicity of these materials is discussed.
Hazard Analysis and Risk Assessment
Authors: Crowl Daniel A. 
Published: July 2004

Abstract

The purpose of hazard analysis and risk assessment in the chemical process industry is to
(1)
characterize the hazards associated with a chemical facility;
(2)
determine how these hazards can result in an accident; and
(3)
determine the risk, ie, the probability and the consequence of these hazards. Methods for performing hazard analysis and risk assessment include safety review, checklists, Dow Fire and Explosion Index, what‐if analysis, hazard and operability analysis (HAZOP), failure modes and effects analysis (FMEA), fault tree analysis, and event tree analysis.

In order to complete an assessment of risk, a probability must be determined.
A more recent concept that could have significant impact on future designs is that of inherent safety. Hazard avoidance is performed by three techniques. First, there is substitution. This means substituting a less hazardous material for the material in use. The second method for inherent safety is attenuation, ie, operating the process at lower temperatures and pressures. The last inherent safety technique is intensification. This means using much smaller inventories of hazardous raw and intermediate materials, and reducing process hold‐up and inventories.
Heat‐Exchange Technology, Heat Pipes
Authors: Bienert Walter B. , Ernst Donald M. , Eastman G. Yale 
Published: July 2004

AbstractHeat pipes are used to perform several important heat‐transfer roles in the chemical and closely allied industries. Examples include heat recovery, the isothermalizing of processes, and spot cooling in the molding of plastics. In its simplest form the heat pipe possesses the property of extremely high thermal conductance, often several hundred times that of metals. As a result, the heat pipe can produce nearly isothermal conditions making an almost ideal heat‐transfer element. In another form the heat pipe can provide positive, rapid, and precise control of temperature under conditions that vary with respect to time.The heat pipe is self‐contained, has no mechanical moving parts, and requires no external power other than the heat that flows through it.
Heat‐Resistant Polymers
Authors: Cassidy Patrick E. , Aminabhavi Tejraj M. , Reddy V. Sreenivasulu 
Published: July 2004

AbstractThe intensive interest in heat‐resistant polymers results from new technological processes requiring higher use temperatures for development. Thermally stable or high performance polymers dictate high melting (softening) temperatures, resistance to oxidative degradation at elevated temperature, resistance to other (nonoxidative) thermolytic processes, and stability to radiation and chemical reagents.A number of thermally stable polymers have been synthesized, but in general the types of structures that impart thermal resistance also result in poor processing characteristics. Attempts to overcome this problem have largely been concentrated on the incorporation of flexible groups into the backbone or the attachment of stable pendent groups. Among the class of polymers claimed to be thermally stable only a few have achieved technological importance, some of which are polyamides, polyimides, polyquinoxalines, polyquinolines, and polybenzimidazoles. Of these, polyimides have been the most widely explored.
Heat‐Exchange Technology, Heat Transfer
Authors: Cho Young I. , Cho S. M. 
Published: July 2004

AbstractIn order to select a proper heat exchanger for a given application, various factors such as pressure, temperature, size, fouling factor, and the use of toxic or corrosive fluids must be considered. These pressure and temperature requirements mainly dictate the type of heat exchanger selected. In general, for high pressures and temperatures, tubular heat exchangers that conform to safety regulations and manufacturing codes are used. For moderate pressures, small but very efficient plate heat exchangers can be employed.There are three heat‐transfer modes, ie, conduction, convection, and radiation, each of which may play a role in the selection of a heat exchanger for a particular application. The basic design principles of heat exchangers are also important, as are the analysis methods employed to determine the right size heat exchanger. The shell‐and‐tube exchanger is the workhorse of power, chemical, refining, and other industries. Plate heat exchangers are used as an alternative in relatively low temperature and pressure applications involving liquids and two‐phase flows. Cold‐plate heat exchangers are used for electronics cooling applications.Heat exchangers are used whenever energy has to be transferred, and the proper design and use of heat exchangers are vitally important for efficient operation of an industrial system, for energy conservation, and ultimately for the protection of the environment. There are numerous design and operating problems originating from a lack of understanding of basic flows and heat‐transfer phenomena such as flow distribution in manifolds, flow‐induced vibration in two‐phase flows, heat‐transfer enhancement, fouling, etc.In order to help companies and organizations overcome problems associated with heat exchangers, for example, Heat Transfer Research Inc. (HTRI) (U.S) and the Heat Transfer and Fluid Flow Service (HTFS) (UK) provide results of heat‐transfer and fluid‐flow research, design methods, supporting computer programs, and proprietary equipment testing.
Heat‐Exchange Technology, Nonaqueous Heat‐Transfer Media
Authors: Minton Paul E. 
Published: July 2004

Abstract
At temperatures below 0°C or above 200°C, heat‐transfer media other than water often are the more optimum choice. Glycol/water, typically ethylene glycol or propylene glycol solutions, are widely used for liquid‐phase secondary cooling and heating applications. Using appropriate inhibitors, the glycol‐based fluids can be used over a temperature range of −50 to 175°C. Glycol/water solutions intended for heat‐transfer systems are manufactured by Union Carbide Corp. and Dow Chemical.