bluuebunny/crossref_metadata_2025 huggingface dataset:
Silicon and Silicon Alloys, Chemical and Metallurgical
Authors: Dosaj Vishu
Published: July 2004

Silicon is a low density element having nonmetallic characteristics. The production of silicon from silica is discussed as is silicon refining technology. The primary uses of silicon are in the chemical, aluminum, and electronics industries. Silicon is the chemical precursor of silicones, a versatile, fast‐growing market, and of advanced ceramics such as silicon nitride. Silicon forms an integral part of the aluminum parts industry; aluminum–silicon alloys are readily cast. Silicon is also important to aluminum production.

Silicon forms alloys with a large number of metallic elements. Many of these alloys are of utmost importance to the production and refining of irons and steels. The most prevalent are the ferrosilicons, production of which is discussed.
Chemotherapeutics, Anticancer
Authors: Doyle Terrence W. , Vyas Dolatrai M.
Published: July 2004

All of the drugs currently approved by the United States Food and Drug Administration for the treatment of cancer, as well as a number of newer experimental agents in clinical trials, are reviewed. The primary focus of the article is on the status of chemotherapy in the 1990s, ie, the direction in which new drug discovery strategies are moving and the criteria used for advancing compounds into clinical trials. In addition, a discussion of the approaches to cytotoxic chemotherapy with special emphasis on drug targeting, toxicity amelioration, and drug resistance has been incorporated. Estimated worldwide sales for the most commonly utilized chemotherapeutic agents is given to demonstrate the increased use of chemotherapy as a modality in the treatment of cancer.
Nuclear Reactors, Chemical Reprocessing
Authors: Godfrey W. L. , Hall J. C. , Townes G. A.
Published: July 2004

The chemical reprocessing of discharged nuclear reactor fuel allows the large quantities of energy found in uranium and plutonium to be recycled back to the reactors while separating out the fission products as a waste stream. The PUREX process, used to recycle nuclear reactor fuel, was developed as part of the U.S. defense program. This process is described. The world's principal fuel reprocessing centers are located in the U.K., France, and Japan. Smaller units are operating in India. No chemical reprocessing takes place in the United States.

Chemical reprocessing involves fuel decladding, mechanically cutting or shearing the tubing in which the nuclear fuel is encapsulated, and fuel dissolution, prior to chemical separation of the nonradioactive materials, the fission products, and the unburned fuel. Several types of countercurrent solvent extraction equipment are used to separate the useful components. The uranium and plutonium products are converted to oxides from which recycle fuel is fabricated. The wastes are safely stored for future disposal.
Chemical Warfare
Authors: Evans Tom J.
Published: July 2004

Chemicals used in war fit into five categories: flame agents, incendiaries, smokes and obscurants, incapacitants and riot control agents, and toxic agents. Flame agents, typically hydrocarbons or other readily flammable liquids, are used in flame throwers and flame projectors such as flame rockets. Incendiaries are often metals such as magnesium or aluminum, or oil and metal mixtures. These materials often require a fuse or ignition cup. Smokes and obscurants may be gaseous, liquid, or particulate aerosols. Incapacitants and riot control agents are designed to incapacitate but not permanently damage. These substances may be atropinemetics, or lacrimators, sternutators, vesicants, or urticants. Effects of atropinemetics may last from a few hours to a few days; effects of the latter materials usually dissipate within minutes upon removal from the agent. The toxic agents are generally of two types, vesicants such as the sulfur or nitrogen mustard gases, or the organophosphate nerve agents. Defense against toxic agents requires agent detection and identification; individual and collective protection of personnel and equipment; decontamination materials and procedures; and medical defense.
Chemometrics
Authors: Vogt Frank , Booksh Karl
Published: July 2004

Chemometrics is the discipline that uses mathematical and statistical methods to design optimal numerical procedures for analyzing chemical data in order to extract maximum chemical information. After a short introduction, the underlying general principles of regression analysis will be presented in the section Linear Regression Analysis, which are the foundations of chemometrics. The formulation is kept in a very general way in order to (1) explain the ideas behind regression analysis thoroughly, (2) to enable a fundamental understanding of chemometrics, and (3) to ensure that these methods can be adapted and applied to all kind of data evaluation tasks. Whenever exemplifications are helpful, spectroscopic applications have been chosen consistently for discussion since they are very descriptive. Once the fundamental mathematical principles are understood, the reader is well prepared for chemometrics. A variety of bilinear chemometric algorithms are presented in the section Bilinear Chemometric Methods, which have been developed for different fields of analytical chemistry. Recently, multiway techniques (the section Multiway Analysis) have been investigated and applied to hyphenated measurement techniques. The section Selected Topics focuses on some applications which are dedicated to more advanced readers and practitioners.
Chemical Product Design
Authors: Moggridge G. D. , Cussler E. L.
Published: July 2004

Chemical products depend for their function on a chemical or a chemical transformation. They are usually of high value, and manufactured in relatively low volumes, which means that the focus in designing chemical products is on speed rather than cost. In designing a new chemical product, the starting point is to define a desired function, rather than a chemical specification; thus chemical product design inevitably encompasses deciding what to make as well as the process by which it will be made. These characteristics of chemical product design result in process design heuristics rarely being appropriate. To replace these, we propose a four step procedure as a template around which to organize ideas for designing chemical products.
Regulatory Agencies, Chemical Process Industry
Authors: Passow Nancy R.
Published: July 2004

The chemical process industry is highly regulated in the environmental, health, and safety area. Everything is affected, from the siting of a new facility to the transportation of raw materials and finished products, from the working conditions for employees to operating requirements for processes, packaging of finished goods, and dealings with the community. The two main U.S. Federal agencies involved in the protection of human health and the environment are the Environmental Protection Agency (EPA) and the Occupational Safety and Health Administration (OSHA). The EPAs principal concern is the protection of the environment; in most cases, the area outside of an industrial facility. Significant laws covered by EPA are the Clean Air Act Amendments (CAAA); the Clean Water Act (CWA); Resource Conservation and Recovery Act (RCRA); Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA); Toxic Substances Control Act (TSCA); and the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA). The principal function of OSHA is the protection of people, eg, employees, visitors, and temporary help, in the workplace. The principal law covered by OSHA is the Occupational Safety and Health Act.
Chiral Separations
Authors: Stalcup Apryll M.
Published: July 2004

Chiral separations are concerned with separating molecules that can exist as nonsuperimposable mirror images. Although chirality is often associated with compounds containing a tetrahedral carbon with four different substituents, other atoms, such as phosphorus or sulfur, may also be chiral. Also molecules containing a center of asymmetry may be chiral. There has been recent awareness that many drugs are chiral and that living systems constitute chiral environments. Hence, the optical isomers of chiral drugs may exhibit different bioactivities and/or biotoxicities. Although a great deal of work is being done in chiral separations related to pharmaceuticals, agricultural and food and beverage industries are affected as well. Traditionally, chiral separations have been considered the most difficult to achieve. A variety of chiral separation strategies have been devised. This article focuses on chromatographically based chiral separations. The use of thin‐layer chromatography, capillary electrophoresis, high performance liquid chromatography, gas chromatography, and liquid chromatography are detailed.
Chlorinated Benzenes
Authors: Krishnamurti Ramesh
Published: July 2004

The chlorination of benzene can theoretically produce 12 different chlorobenzenes. However, technology and world events have substantially reduced chlorinated benzene to the current production of three significant products: monochlorobenzene ando‐ andp‐dichlorobenzenes. Monochlorobenzene represents over 50% of the total production of chlorobenzenes. The largest use for monochlorobenzene worldwide is the production of nitrochlorobenzenes, which are consumed to make dye and pigment intermediates, rubber processing chemicals, pesticides, pharmaceuticals, and other organic intermediates.o‐Dichlorobenzene is consumed primarily for 3,4‐dichloroaniline manufacture in the United States and Western Europe and in the emulsified form in Japan for treatment of garbage. The largest market worldwide forp‐dichlorobenzene is for deodorant blocks and moth control. A growing use is in the production of the high performance polymer, poly(phenylene sulfide) (PPS).

Manufacturing methods, specifications, handling precautions, and health and safety factors are covered. With the exception of their use in the production of high performance polymers, markets for chlorobenzenes are mature and overall demand is expected to show little, if any, growth over the next few years.
Chlorophenols
Authors: Desmurs Jean‐Roger , Ratton Serge
Published: July 2004

Chlorophenols are generally prepared by chlorinating phenol. Monochlorophenols, dichlorophenols, and trichlorophenols are used as intermediates for the synthesis of agrochemical compounds. Pentachlorophenol is used directly for the protection of wood. Chlorophenols are subjected to particularly severe quality control analyses.

As well as quality improvement, the adoption of new analysis technology has resulted in a better understanding of chlorination mechanisms and of the formation of impurities liable to be found in certain chlorophenols. These studies have led to the introduction of new chlorination techniques using specific catalysts that permit controlled selective introduction of chlorine into the core and the elimination of certain products (2,4,5‐trichlorophenol) in 2,4,6‐trichlorophenol. Chemical processing stabilizes chlorophenols at the end of chlorination and avoids their evolution.
Chloroform
Authors: Holbrook Michael T.
Published: July 2004

Chloroform, CHCl3, at normal temperature and pressure is a heavy, clear, volatile liquid with a pleasant, ethereal, nonirritant odor. It is produced almost exclusively by the chlorination of methane or lower chlorinated methanes, though methane oxychlorination and carbon tetrachloride hydrogenation have been proposed. The U.S. chloroform capacity has been estimated at 327,000 t/yr but the actual capability is probably much higher because of the producer's ability to change their product mix between methylene chloride and chloroform. The main uses for chloroform are in the production of HCFC‐22 and fluoropolymers. Chloroform is regulated under a number of federal and state laws.
Chlorinated Paraffins
Authors: Houghton Kelvin L.
Published: July 2004

Chlorinated paraffins are well‐established products in a wide range of diverse applications in today's modern industry. Although as a class of products they have been available for over 50 years, their continuing use results from manufacturers taking advantage of new base feedstocks to develop advanced products to meet the increasing technical demands of the new and emerging technologies. The physical and chemical properties of chlorinated paraffins are determined by the carbon chain length of the paraffin and the chlorine content.

The range of products now available are used as plasticizers in PVC, rubber, surface coatings, adhesives, and sealants where they impart the added benefits of fire retardance and chemical and water resistance. As fire‐retardant additives they find specific usage in polyester resins, polyurethanes, and polyolefins. Chlorinated paraffins are also employed as extreme pressure additives in metal‐working lubricants, as components of fat liquors for leather treatment, and as solvents in carbonless copying paper.

Comprehensive studies on toxicity and environmental impact have been carried out over many years. The acute toxicity of chlorinated paraffins to mammals, birds, and fish is low. Although there is evidence of toxicity to some aquatic species, interpretation of the results is made complicated because of the very low solubility of chlorinated paraffins in water.
Chlorine Oxygen Acids and Salts, Chlorous Acid, Chlorites, and Chlorine Dioxide
Authors: Kaczur Jerry J. , Cawlfield David W.
Published: July 2004

Chlorine dioxide is finding increasing use as an oxidizing bleaching agent in the pulp and paper industry, replacing chlorine gas and aqueous sodium hypochlorite. Chlorine dioxide significantly reduces the quantity of adsorbable organically bound halide (AOX) effluents produced in the paper pulp bleaching process while producing high brightness paper with excellent mechanical strength. Increasing chlorine dioxide bleaching substitution levels in the pulp mills as well as the need for a chlorine‐free gas for bleaching are the driving forces for design/process changes in the commercial chlorine dioxide generators that use sodium chlorate.

Chlorine dioxide is also increasing in usage as a disinfectant or biocide in municipal and industrial water treatment as well as an oxidizer in oil field and pollution abatement processes. Sodium chlorite is the choice precursor chemical for generating chlorine dioxide gas in quantities of less than about 2000 kg/d. Chlorine dioxide has been shown to be an effective biocide as well as an effective oxidizer for the control of total trihalomethanes, in drinking water treatment to meet USEPA drinking water regulations. Methods for the removal of the disinfection by‐products produced from chlorine dioxide treatment, such as chlorite and chlorate, are being developed to alleviate toxicological concerns about their presence in drinking water.
Chlorohydrins
Authors: Richey W. Frank
Published: July 2004

Chlorohydrins are best described as aliphatic compounds having chloro and hydroxyl substituents on adjacent carbon atoms. These compounds are most commonly manufactured by the reaction of an alkene with chlorine and water though many other methods of preparation are known. The most useful reaction of chlorohydrins is dehydrochlorination to form oxirane compounds. Propylene oxide and epichlorohydrin are produced on an industrial scale via chlorohydrin intermediates.
Chloroprene
Authors: Stewart Clare A.
Published: July 2004

Chloroprene [126‐99‐8], 2‐chloro‐1,3‐butadiene, is prepared from butadiene by chlorination followed by dehydrochlorination of the intermediate 3,4‐dichloro‐1‐butene. It is used almost exclusively in the production of neoprene (CR, chloroprene rubber). Because of problems of stability toward polymerization and dimerization, it is usually manufactured only as needed for polymer manufacture.
Chromatography
Authors: Dybowski Cecil , Kaiser Mary A.
Published: July 2004

This article presents an introduction to chromatography, a fundamental technology for separation of components of a mixture. The major chromatographic methods are described: gas chromatography, liquid chromatography, thin‐layer chromatography, paper chromatography, supercritical fluid chromatography, and capillary electrophoresis. Major components of each type of chromatographic system are discussed, to enable the reader to understand each technology and its applications in chemistry and analysis. References to relevant books and articles are given to provide access to detailed information on each technology.
Chromatography, Gas Chromatography‐GC
Authors: Snow Nicholas H. , Slack Gregory C.
Published: July 2004

Gas chromatography, in which a gaseous moving phase is passed over a liquid or solid stationary phase within a column, is one of the most widely used instrumental analysis techniques today. This article provides a basic overview of gas chromatographic theory, instrumentation and technology. Descriptions of common modes of gas chromatography: packed and capillary columns, inlets, columns, detectors, data systems, multidimensional separations and fast GC are provided. The text is heavily referenced to major texts and research articles for further study.
Chromium and Chromium Alloys
Authors: Papp John F. , Lipin Bruce R.
Published: July 2004

Chromium metal, chromium alloys, and metallurgically important chromium compounds are reviewed. Occurrence, mining, and smelting of chromium ores are discussed. South Africa and Zimbabwe hold about 80% of thein situcontained chromium. Details onSuppliesand availability worldwide are given. The chemical, physical, and mechanical properties of chromium metal are summarized. Important Cr‐bearing alloys: the various stainless steels, alloy steels, nonferrous alloys, and Cr‐based alloys are identified as are metallurgically important compounds. Applications of these materials are discussed and the contribution of chromium to the properties of these alloys is described. Methods of producing Cr‐rich protective and decorative surfaces, recovery and reuse of Cr‐bearing materials, and toxicology are reviewed. Economic data regarding operating and transportation of are discussed as well as international markets.
Cinnamic Acid, Cinnamaldehyde, and Cinnamyl Alcohol
Authors: Eilerman Robert G.
Published: July 2004

Cinnamic acid, Cinnamaldehyde, and Cinnamyl Alcohol.Eilerman, Robert G. (Givaudon‐Roure Corp.). The earliest references to cinnamic acid, cinnamaldehyde, and cinnamyl alcohol are associated with their isolation and identification as odor‐producing constituents in a variety of botanical extracts. Widespread use of cinnamic derivatives, principally in flavor and fragrance compositions, has resulted in the development of straightforward methods for the production of their synthetic equivalents. Commercial processes have focused on condensation reactions between benzaldehyde and a number of active methylene compounds for assembly of the requisite carbon skeleton. The presence of a disubstituted carbon‐carbon double bond in the side chain of these chemicals gives rise to the existence of two distinct stereoisomers, referred to as the cis (Z) and trans (E) isomers.

Cinnamic acid is manufactured by the Perkin rection. The olfactive properties of cinnamate esters are well suited to fragrance applications in soaps and cosmetics. The essential oils from several varieties of cinnamon bark contain cinnamaldehyde as a primary component. This aldehyde is produced exclusively by the base‐catalyzed condensation of benzaldehyde with acetaldehyde. It is used primarily in baked goods, chewing gum, and pharmaceutical products, ie, toothpaste and mouthwash, where a spicy, cinnamon character is required. Cinnamyl alcohol and its derivatives are widely employed in perfumery to add balsamic notes to blossom compositions. Its commercial production is accomplished by the reduction of cinnamaldehyde.
Citric Acid
Authors: Lopez‐Garcia Rebecca
Published: July 2004

Citric acid is a natural component and common metabolite of plants and animals. It is the most versatile and widely used organic acid in foods, beverages, and pharmaceuticals.

Because of its functionality and environmental acceptability, citric acid and its salts (primarily sodium and potassium) are used in many industrial applications for chelation, buffering, pH adjustment, and derivitization. These uses include laundry detergents, shampoos and cosmetics, enhanced oil recovery, and metal cleaning.

This article details its occurrence in nature, the physical and chemical properties of citric acid, and commercial manufacturing, processing, shipping, and storage information. Descriptions are given of the two common methods to recover citric acid from its fermentation broth: lime‐sulfuric acid recovery and also liquid extraction.

Commercial considerations including worldwide production and U.S. distribution end use are reviewed. Various national compendial specifications for citric acid and common analytical test methods are discussed. Health and safety factors including environmental concerns are addressed.
Coal
Authors: Hower James
Published: July 2004

Coal is a vital component of energy utilization throughout the world, including the United States, where coal is responsible for >50% of the electricity production. Sixteen countries each produce >1% of the world's coal production, with China and the United States leading, each with >23% of world production. In this article, various aspects of coal petrology, chemistry, and physical structure are discussed. Utilization aspects, including coking, combustion, gasification, and liquefaction are considered. Combustion accounts for most of the world utilization, with gasification and other clean‐coal technologies holding promise for future applications. In the United States and many other countries, environmental regulations have impacted the quality of coal used in combutstion, with the tendency to use lower sulfur coals evident in the U.S. power industry's shift from Eastern U.S. bituminous to Wyoming subbituminous coals. Coke production, while still an important user of coal, has declined. Liquefaction, despite the promise of providing an alternative to petroleum, has not been widely commercialized.
Feedstocks, Coal Chemicals
Authors: Worsham Paul R.
Published: July 2004

Worsham, Paul R. (Eastman Chemical Company). Many basic chemicals currently produced from petroleum can be produced from coal using demonstrated technology, including coal carbonization, direct liquefaction, and coal gasification. A broad range of chemicals is available by gasification of coal to make synthesis gas and subsequent transformation with existing processes to methanol, ammonia, acetyl derivatives, and Fischer‐ Tropsch products. Other useful chemical products can be isolated from the liquid by‐products of coke production and gasification. These products include pitch, creosote, naphthalene, and cresylic acids. Some of these same products are recovered from modern synfuel plants producing liquid transportation fuels and synthetic natural gas. Another group of chemicals can be produced from coal‐derived acetylene.

The choice of feedstock for a chemical process depends on complex technical, economic, environmental, and political factors. Except in special situations, the manufacture of most chemicals from coal is not competitive with petroleum and natural gas at feedstock prices prevailing in the early 1990s. Special situations typically are the result of the concurrence of several favorable factors such as location of producing facilities close to coal supplies which match the needs of the desired operation, coupled with the availability of modern conversion processes which can take advantage of coal composition to generate high value products with minimal conversion to the hydrogen/carbon ratio of competing feedstocks.
Coated Fabrics
Authors: Barden Bruce
Published: July 2004

A coated fabric is an engineered product derived by a combination of textile and polymer coating technology. Each type of coated fabric is designed to fulfill the requirements of a specific application. The textile substrate is chosen based on a knowledge of the strength and dimensional control requirements of the finished product. The coating, a product of polymer compounding knowledge, is chosen for its specific properties such as abrasion resistance, oil resistance, resistance to leaching, etc. The components, processing, testing, and uses of coated fabrics are discussed.
Coatings
Authors: Wicks Zeno W.
Published: July 2004

Organic coatings are discussed with an emphasis on the scientific understanding of the chemistry and performance of coatings. Topics covered include film formation, including solvent evaporation from films, film formation from thermosetting resins, coalescence of polymer particles; flow, including, viscosity of resin solutions, viscosity of systems with dispersed phases; mechanical properties; exterior durability, adhesion including adhesion to metals, adhesion to plastics and coatings, testing for adhesion, corrosion protection, including protection by intact films, protection by nonintact films; resins for coatings including latexes, amino resins, urethane systems, epoxy resins, acrylic resins, polyester resins, alkyd resins, other coatings resins; volatile components, color and appearance, including color matching, gloss, pigments, pigment dispersion, pigment volume relationships; application methods; film defects, including leveling, sagging, crawling and cratering, floating and flooding, wrinkling, foaming, product coatings, coatings for metal, wood products coating, radiation curing coatings, powder coatings; architectural coatings, including flat wall paints, exterior house paints, gloss enamels; special purpose coatings, including maintenance paints, marine coatings, automobile refinish paints, other special purpose paints; and economic aspects of the coatings industry.
Cobalt and Cobalt Alloys
Authors: Hodge F. Galen , Dominey Larry
Published: July 2004

Cobalt is a metallic element the earliest uses of which were as colorants for glass and pottery. Cobalt has unique magnetic properties. The largest consumption of cobalt is in the metallic form as magnetic alloys, cutting and wear‐resistant alloys, and high temperature superalloys. The second largest use of cobalt is in the form of salts, including lacquers, enamels, colorants for glass, and catalysts. Radioactive cobalt has considerable application in radiochemistry and radiography.

Cobalt‐base alloys are generally described as wear‐resistant, corrosion‐resistant, and heat‐resistant. Many of the properties of the alloys arise from the crystallographic nature of cobalt, the solid solution strengthening effects of chromium, tungsten, and molybdenum, the formation of carbides, and the corrosion resistance imparted by chromium.
Cobalt Compounds
Authors: Richardson H. Wayne
Published: July 2004

An overview of cobalt compounds including the chemistry exhibited by the +2 and +3 valences is presented emphasizing those compounds of industrial significance. Methods of manufacture for many of the commercial compounds are given as is transition‐metal separation methodology. The biological role of cobalt in humans and ruminants is discussed.

The two fluorides of cobalt, namely the cobalt(II) fluoride and the cobalt(III) fluoride, are of great importance in the fluorochemical industry owing to the use of the latter as a hard fluorinating agent. It is used for the replacement of hydrogen by fluorine in halocarbons, fluorination of alkynes, and fluorination of aromatic compounds.

The primary use of cobalt compounds is in catalysis for hydrotreating petroleum resulting in hydrodesulfurization. Cobalt catalysts are also used to denitrify, deoxgenate, crack crude oil and gas, and in homogeneous oxidation and the oxo process (hydroformylation). Cobalt compounds are used in pigments for paints and printing inks, as colorants for glass, ceramics, and enamels, and in the form of metallic soaps as driers. Other industrial uses are in electronics, agriculture as feed and soil additives, and as an adhesive in the tire industry.
Colorants for Ceramics
Authors: Eppler Richard A.
Published: July 2004

The three ways to color a vitreous ceramic coating are described, along with the materials available for that purpose. Also described are the requirements for use of these materials in ceramic coatings.
Color Photography
Authors: Kapecki Jon , Rodgers James
Published: July 2004

Color photography is the technology by which the visual appearance of a three‐dimensional subject may be reproduced on a two‐dimensional surface having a pleasing balance of brightness, hue, and color. Light capture is primarily effected by silver halide crystals. Integral tri‐color film packs also contain spectral sensitizing dyes and colored masking couplers appropriate to the subtractive primary dyes, filters, and an overcoat.

The chromogenic chemistry of the color photography process involves the reactions ofp‐phenylenediamine developers and various couplers. Prototype dye couplers, which often contain an organic ballast to enhance solubility in hydrophobic solvents, colored masking couplers, and development‐inhibitor‐releasing couplers, which carry a silver development inhibitor linked to the film coupling site, are given. Both chromogenic and post‐development film chemistries are described as are the relationships between film speed, light sensitivity, dye stability, image structure, and color reproduction.
Colorants for Foods, Drugs, Cosmetics, and Medical Devices
Authors: Marmion Daniel
Published: July 2004

This article includes a brief history of the use of colorants in foods, drugs, cosmetics, and medical devices, and the development of legislation in the United States to control them. It describes where and why colorants are used, lists all those currently in use, identifies each as either needing certification or not, and describes the chemical and physical properties, method of manufacture, chemical structure, chemical classification, and uses of each. Individual and general restrictions relating to the use of colorants are described, and sample specifications are shown. The weight of each colorant certified in the United States each year from 1983 to 1990 is given. Includes references and sources for more information regarding colorants including their analysis as is and in product matrices.
Color
Authors: Nassau Kurt
Published: July 2004

Two theories of color perception have been dominant. The trichromatic theory relates to blue‐, green‐, and red‐sensitive cones in the retina of the eye. It explains various forms of color blindness and is the basis of the 1931 CIE chromaticity diagram (color triangle) using
x,y,Y
and the 1976 CIELUV color space using L*, u*, v*. The opponent theory uses the opposites light/dark, red/green, and blue/yellow. It explains a variety of perception phenomena and is the basis of the 1976 CIELAB color space using L*, a*, b*. These apparently incompatible approaches apply to different parts of the color perception process. Modern electronic instruments have greatly simplified the measurement of color.

In considering color mixtures, it is important to distinguish two types, having different sets of primary colors and having different results for color mixing. In subtractive color mixing, applying to paints and dyes, the addition of the three primary colors absorbs all light and produces black; here mixing blue and yellow paints produces green. In additive color mixing, applying to beams of light and video displays, the addition of the three primary colors reconstitutes the full spectrum and produces white; here mixing blue and yellow light beams produces white.

Fifteen distinct chemical and physical mechanisms explain the various causes of color, all involving the behavior of electrons in matter. Vibrations and simple excitations explain the colors produced by incandescence (flames), gas excitation (vapor lamps), and vibrations and rotations (blue of water). Ligand‐field effects give the colors of transition‐metal compounds and impurities (turquoise and ruby, respectively). Molecular orbitals give the colors in organic compounds (dyes) and charge‐transfer compounds (blue sapphire). Energy bands lead to the colors of metals (copper), semiconductors (vermilion), doped semiconductors (blue diamond), and color centers (amethyst). Geometrical and physical optics explain colors from dispersive refraction (prism spectrum), scattering (blue sky), interference (soap bubble), and diffraction (opal).
Photography, Instant
Authors: Mervis Stanley H. , Walworth Vivian K.
Published: July 2004

Instant photography began in 1947 with a one‐step print process providing a finished photograph within a minute after exposure. Outwardly dry processing under ambient conditions is initiated within the camera upon release of reagent from a sealed pod that is provided as part of the film unit. Instant color photography was introduced in 1963. Integral print films, introduced in 1972, retain the developed photosensitive layers concealed within the print. Instant film configurations also include print and transparency processing independent of the camera. Subtractive instant color processes use dye developers and dye‐release compounds to generate images comprising preformed dyes. Additive instant color transparencies comprise microscopic black‐and‐white silver images formed by exposure of a panchromatic emulsion layer through an integral color screen. The chemistry of the various systems is discussed. Instant color films are utilized in many professional fields.
Conveying
Authors: Thomson F. M.
Published: July 2004

The transport of bulk solids by conveying is an integral part of the chemical industry. A wide range of mechanical and pneumatic conveying equipment, designed to meet the handling requirements of a variety of materials, is available. The selection and design of bulk handling conveyors required for any specific task are based on matching the characterisitics of the conveyor to the handling and flow behavior of the material to be conveyed. Material flow behavior is determined by combining data from bench‐top experiments and previously observed plant performance. The more recent advances in conveyor technology have centered around the design of belt conveyors and of dense phase pneumatic conveying systems.

Various types of mechanical and pneumatic conveyors are discussed and the dependence of conveyor selection on material characteristics is emphasized. Components, design, and power requirements are considered.
Copolymers
Authors: Leiza José R. , Asua José M.
Published: July 2004

The preparation, properties, use, and characterization of synthetic copolymers is reviewed and future trends are discussed. The different copolymer structures are detailed and the nomenclature is explained. The copolymerization reactions (free radical including controlled free radical, anionic, cationic, ring‐opening, catalytic, and step growth) are discussed emphasizing the copolymer structures attainable through each polymerization mechanism. Industrially important random, alternating, block, graft, star, and hyperbranched copolymers are discussed in terms of the processes used to produce them and the properties achieved. Their main uses and trade names are also detailed. Future trends are discussed.
Copper Compounds
Authors: Wayne Richardson H.
Published: July 2004

An overview of copper compounds is presented with the emphasis on those compounds of key industrial importance. The chemistry and stability of copper in its various oxidation states and with regard to coordination complexes are discussed. The primary methods of manufacture for many commercially significant compounds are given as are the most usual methods of analysis. The uses of copper in agriculture, as a nutritional fungicide and algicide are discussed. The various copper‐bond fungicides are listed. Other uses of copper compounds such as in catalysis, electronics, and electroplating are mentioned. Copper compounds are also used as pigments, in wood preservation and electroless plating, and in solar collectors.
Copyrights
Authors: Koenigsberg I. Fred
Published: July 2004

Copyright developed after the invention of the printing press as a means of protecting works of authorship. The United States copyright law derives from a constitutional grant to Congress to promote progress in science, knowledge, and learning. Copyright protects original works of authorship of all types. Copyright does not protect ideas, concepts, methods, systems, processes, research, or facts themselves, but only their expression. Copyright may protect utilitarian works, but only to the extent that they contain physically or conceptually separable original works of authorship.

Copyright is a property right and may be transferred or licensed and owned jointly. Copyright is owned initially by the author, usually the human creator of the work. However, in the case of works made for hire, the employer or other person for whom the work is created is deemed to be the author. Copyright formalities, that is, notice, deposit, and registration, are of less importance now than they were previously, but are still encouraged. No copyright notice is necessary on copies of works first published after March 1, 1989. Copyright registration is entirely permissive, but enables important legal procedural rights and remedies.

Copyright generally endures for the life of the author plus 70 years, for works first created or copyrighted on or after January 1, 1978; or for an initial term of 28 years and a renewal term of 67 years, for works first copyrighted before January 1, 1978. Copyright protects the rights to reproduce the work in copies, to prepare derivative works, of public distribution, of public performance, and of public display. These rights are not absolute, because certain exceptions, such as the fair use and first sale doctrines, apply.
Cotton
Authors: Wakelyn Phillip J.
Published: July 2004

Cotton is both a fiber and food crop that is grown in about 80 countries. Annually in the world about 90 million 217.7 kg (480 lbs) bales [∼19.6 million metric tonnes (21.6 million tons)] of cotton fiber and 27 million metric tonnes (29.8 million tons) of cottonseed are produced. Cotton is the most important natural fiber (about 37% of the textile fiber consumed in the world in 2002) used to produce apparel, home furnishings, and industrial products. Cottonseed is the world's No. 3 oilseed, used for vegetable oil, animal feed, and linters. Over 90% of the world's cotton production is upland cotton (G. barbadense. In 2002 transgenic varieties are about 25–30% of the cotton grown in the world. Commercial cottons are white. There has been some interest in naturally colored cottons (shades of brown and green are the main colors) and organic cotton but, at present, there is very little production of these cottons [< 20,000 bales worldwide; < 4455 metric tonnes (4800 tons)]. The origin, biosynthesis, biology, development, production, harvesting ginning, classification, physical properties, morphology, physical structure, chemistry, reactivity, economic aspects, utilization, and health and safety are reviewed.
Cryogenic Technology
Authors: Agrawal Rakesh , Herron D. Michael , Rowles Howard C. , Kinard Glenn E.
Published: July 2004

By accepted international standard, the term “cryogenic” refers to phenomena and processes occurring at or using temperatures <120 K. “Permanent” gases, such as oxygen, and helium, can be liquefied at ambient pressure at temperatures of 120 K or below.

Cryogenic technology has contributed greatly to scientific research and has found a wide range of industrial applications. Cryogenic condensation and distillation processes are widely used to produce high purity oxygen, argon, nitrogen, hydrogen, and helium for the chemical, metal, and electronic industries. These gases and others, such as natural gas, are commonly stored and shipped as cryogenic liquids rather than as pressurized gases. Cryogenic processes are also used to provide low temperatures to refrigerate, freeze, and store other materials, such as food and biological tissue, or to alter the properties of materials, as with superconductivity.

A wide variety of specialized equipment has been developed for cryogenic processes and apparatus, including compressors, expanders, heat exchangers, and distillation columns. Specialized materials have also been developed to insulate cryogenic equipment, transfer lines, storage tanks, and transport vehicles.
Crystal Engineering
Authors: Braga Dario , Grepioni Fabrizia
Published: July 2004

Crystal engineering is the bottom‐up construction of functional materials from the assembly of molecular or ionic components. The discipline bridges supramolecular and solid‐state science. Crystal engineering is highly interdisciplinary and spans across all traditional sectors of chemistry (organic, inorganic, organometallic, biological chemistry). Beside theconventionaltools of molecular and supramolecular synthetic chemistry, crystal engineering requires the utilization of solid‐state and solid–gas techniques, including theoretical and advanced crystallography methods.
Crystallization
Authors: Ulrich Joachim
Published: July 2004

This article provides an overview of crystallization that can be used by scientists and engineers, regardless of their familiarity with the operation. Key aspects of the use of crystallization for separation, purification, or other purposes are covered; especially noteworthy is the coverage relating product purity, morphology, and size distribution to the kinetic phenomena of crystal nucleation and growth. Current studies have shown that crystallizer variables such as mixing and the rate at which supersaturation is generated influence the purity of recovered crystals. Crystal morphology can be affected by variables modifying inherent growth kinetics of crystal faces or by changing interfacial or solution properties. Molecular modeling is a tool to understand and predict morphologies or changes of morphologies due to additives/impurities. Theory is mixed with empiricism in showing the role of operating variables such as supersaturation, magma density, and agitation in determining crystallization kinetics. Methods are illustrated for coupling crystallization kinetics with population balances on continuous and batch crystallizers to determine crystal size distributions. In addition, the bases of using selective removal functions (clear‐liquor advance, classified‐fines removal, and classified‐product removal) to influence the characteristics of size distributions is presented. Qualitative characteristics of batch crystallizers are presented and the role nucleation plays in determining the general behavior of product size distributions from such systems is described. Finally, a summary of industrial practices and equipment is presented; both crystallization from solution and from the melt are included in the summary. Attention is given to the emerging importance of crystallization from the melt.
Cyanohydrins
Authors: Cholod Michael S.
Published: July 2004

A cyanohydrin is an organic compound that contains both a cyanide and a hydroxy group on an aliphatic section of the molecule. Cyanohydrins are usually α‐hydroxy nitriles which are the products of addition of hydrogen cyanide to the carbonyl group of aldehydes and ketones. The outstanding chemical property of cyanohydrins is the ready conversion to α‐hydroxy acids and derivatives, especially α‐amino and unsaturated acids. Cyanohydrins are highly toxic by inhalation or ingestion and moderately toxic through skin absorption. Cyanohydrins are used primarily as intermediates in the production of other chemicals. Manufacture of methyl methacrylate, used to make acrylic molding resins and clear sheet from acetone cyanohydrin, is the most economically important cyanohydrin process.
Acrylic Ester Polymers, 2‐Cyanoacrylic Ester Polymers
Authors: O'Connor J. T.
Published: July 2004

The polymers of the 2‐cyanoacrylic esters, more commonly known as the alkyl 2‐cyanoacrylates, are hard glassy resins that exhibit excellent adhesion to a wide variety of materials. The polymers are spontaneously formed as very reactive liquids, and the excellent adhesion properties of the cured resins combine to make these compounds a unique class of single‐component, ambient‐temperature‐curing adhesives of great versatility. The materials that can be bonded run the gamut from metals, plastics, most elastomers, fabrics, and woods to many ceramics. The cyanoacrylic esters are prepared via the Knoevenagel condensation reaction, in which the corresponding alkyl cyanoacetate reacts with formaldehyde in the presence of a basic catalyst to form a low molecular weight polymer. Subsequently, the polymer is cracked and redistilled at a high temperature onto a suitable stabilizer combination to prevent premature repolymerization. Good ventilation when using the adhesives is essential. Both the liquid and cured 2‐cyanoacrylic esters support combustion. Some of the market segments served by these versatile materials include automotive, electronic, hardware, cosmetics, and medical devices.
Cyanamides
Authors: Cameron William
Published: July 2004

Cyanamide has been commercially available, as calcium salt, since the beginning of the twentieth century. A commercial process for manufacturing a pure grade of cyanamide was introduced in 1964. Cyanamide was widely used as a nitrogen fertilizer and later as a raw material for dicyandiamide and melamine.

The use of cyanamide as a fertilizer has been replaced by ammonia and urea. Melamine is now made by a petrochemical process using natural gas. Cyanamide is still used in the manufacture of dicyandiamide and calcium cyanide. Cyanamide‐based chemicals have also been used in special applications for defoliants, fungicides, herbicides, and as a weed killer. In pure form, cyanamides are used in the synthesis of many complex chemicals.

Calcium cyanamide is produced by both batch oven and continuous kiln processes. This article deals with the chemistry, manufacture, specifications, health and safety factors (toxicity and environment), and use of cyanamide homologues: cyanamide, dicyandiamide, and melamine.
Databases
Authors: Williams Martha E. , Grant James L.
Published: July 2004

Databases may be considered a research tool for the chemical industry whether for researchers, applications engineers, or marketing or legal personnel. Growth in the dynamic database industry is discussed in terms of numbers of database records, online searches, databases, database producers, and database vendors. Databases may be classified by form of data representation, subject categories, medium of distribution, geographic origin, or status of the producer or vendor. Online connections to databases may involve terminals or personal computers. Alternatively, some databases are available on CD‐ROM.

Commercially available databases in the fields of chemistry, biochemistry and biophysics, geochemistry and mineralogy, biology and medicine, engineering, mathematics, and physics, and in claims and patents are given.