bluuebunny/crossref_metadata_2025 huggingface dataset:
Design of Experiments
Authors: Hahn Gerald J. , Patterson Angela N.
Published: July 2004

The statistical design of experiments is an essential ingredient of successful product development and improvement, and provides an efficient and scientific approach to obtaining meaningful information. In contrast to traditional “vary one‐factor‐at‐a‐time experimentation, variables are changed together, permitting evaluation of interactions. Standard texts give details about the construction of specific test plans, such as incomplete block, full and fractional factorial, and response surface designs, and the analysis of the resulting data. This article gives a brief overview. We focus on the fundamental elements of experimental design: defining the purpose and scope of the experiment, differentiating between alternative types of experimental variables, understanding the underlying environment and constraints, and conducting stage‐wise experimentation. Brief discussions dealing with the emerging topic of combinatorial chemistry, statistical analysis tools, multiple response variables, and some historical background are also provided. Two key features of the article are the description of commercial software for the design and analysis of experiments, and a detailed discussion, including recommendations, of texts on experimental design; both of these include comparative tabulations of technical features.
Dewatering
Authors: Morey Booker
Published: July 2004

The basic process of dewatering is the removal of residual liquid left in a filter, centrifuge, or other cake from a soid‐iquid separation step. Forces used for dewatering are compression, expression, and displacement. The mechanical and electrical methods of dewatering as well as the chemical and mechanical pretreatments of slurries to improve the final dewatering step are discussed. Many of the methods are useful for deliquoring in general and are not limited to water removal. Pretreatments enhance the separation of liquid from solid by lowering the viscosity of the liquid (raising temperature, adding another liquid), lowering surface tension (adding surfactants), increasing porosity or changing compressibility (coagulation, flocculation, pelletizing flocculation, oil agglomeration, pH change, hot or cold thermal treatment, biological conditioning, adding filter aids, magnetic agglomeration), or displacement of the residual moisture (with a gas or a different liquid or by extraction of the solid into a different liquid). Electrical processes can be used to increase the migration of water through a filter cake, to retard the movement of particles into a filter cake, or to be combined with an acoustical field to improve the removal of water from a filter cake.
Dialysis
Authors: Lysaght Michael J. , Baurmeister Ulrich
Published: July 2004

Dialysis is a membrane separation process in which permeating species diffuse across a selective barrier in response to a difference in concentration. Less efficient than other industrial membrane unit operations, dialysis finds appeal chiefly in those biotechnology and food processing applications requiring gentle, isothermal, nondenaturing operating conditions. The popularity of dialysis as general laboratory technique for the separation, concentration, and purification of macromolecules has waned. In contrast, microdialysis, a continuous technique for estimating solute concentration
in vivo
without blood sampling, is increasing in importance, especially in neuropharmacological protocols. By far the largest and most formidable application of dialysis is for the chronic intermittent extracorporeal therapy of end stage kidney disease. In 1992, over 60 million highly optimized disposable hemodializers were produced to support a population of over 400,000 patients with renal failure.
Diamines and Higher Amines, Aliphatic
Authors: Sridhar Srivasan , Carter Richard G.
Published: July 2004

The aliphatic diamine and higher amine family encompasses a wide range of multifunctional and multireactive compounds. The so‐called ethyleneamines family, which includes ethylenediamine and its homologues, the polyethylene polyamines, have found the broadest commercial application. Representative physical and chemical properties are given. Three main processes are used currently to produce the ethyleneamines: the reaction of ethylene dichloride with ammonia to produce the whole spectrum of ethyleneamine products; the reductive amination of monoethanolamine to produce the lighter ethyleneamines, mainly ethylenediamine; and the catalytic reaction of monoethanolamine with ethylenediamine to produce higher ethyleneamines. Worldwide capacity for ethyleneamines is about 295 t/yr. Typical specifications and test methods, storage and handling guidelines, and health and safety factors are discussed. This family of compounds finds use in a wide variety of applications by virtue of their unique combination of reactivity, basicity, and surface activity. With a few significant exceptions, they are used predominantly as intermediates in the production of functional products. Significant applications include fungicides, lubricant and fuel additives, epoxy curing agents, polyamide resins, paper resins, and chelates.
Amines, Aromatic, Diaminotoluenes
Authors: Toseland Bernard A. , Simpson Mark S.
Published: July 2004

Toluenediamine (diaminotoluene,m‐TDA) is an important industrial chemical intermediate; it is produced in the largest volume of any arylamine and is the lowest priced diamine. The principal use for TDA is in the manufacture of toluenediisocyanate (TDI), the predominant diisocyanate in the flexible foams and elastomers industries. Although all six possible toluenediamine isomers are made in the commercial synthesis, only two products are available commercially. The aromatic toluenediamines undergo typical amine reactions. The general chemistry is similar to that of the phenylenediamines or the cyclohexanediamines. Reactions of industrial importance involving commercial toluenediamines include phosgenation, ring alkylation, alkoxylation, and diazotization. Dinitrotoluenes can be catalytically hydrogenated to toluenediamines under a wide variety of temperatures, pressures, and solvents. Toluenediamine is classed as toxic. TDA is readily absorbed through the skin and this is the major route of human exposure.
Amines, Aromatic, Diarylamines
Authors: Layer Robert W.
Published: July 2004

Diarylamines are compounds that have two aromatic groups and one hydrogen atom attached to nitrogen. Diphenylamine (DPA) orN‐phenylbenzenamine, is the most commercially significant diarylamine. It is manufactured by heating aniline by itself, or with phenol, and with an acid catalyst at high temperatures. It is used as a stabilizer for nitrocellulose propellants. When alkylated, diphenylamine finds its largest application as an antioxidant and stabilizer for oils, greases, polymers, and elastomers. Diarylamines that contain other functional groups, such as hydroxyl or amino, are useful dye intermediates, antiozonants, hair dyes, and color photography intermediates. Important reactions of diarylamines include C‐alkylation and oxidation. Diarylamines are manufactured by the self‐condensation of a primary aromatic amine in the presence of an acid, or the reaction of an arylamine with a phenol at high temperatures. Industrial poisoning by diphenylamine has been encountered and appears clinically as bladder symptoms, tachycardia, hypertension, and skin problems. There is no federal standard for permissible exposure limits in air, but the American Conference of Government Industrial Hygienists (1983/1984) has adopted a time‐weighted average value of 10 mg/m3and set a short‐term exposure limit of 20 mg/m3.N‐Nitrosodiphenylamine can act as a nitrosating agent for other amines. Diarylamines based on polycyclic aromatic amines also tend to be more harmful.
Diatomite
Authors: Engh Kenneth R.
Published: July 2004

Diatomite, also known as kieselguhr, or diatomaceous earth, is a naturally occurring, highly structured, fine hydrous silica powder made up of the remains of planktonic algae. Diatomite is used in many applications as the uniquely porous nature of each particle gives diatomite high surface area, low bulk density, high permeability, high water absorption, and low abrasion. Diatomite filter aids are used to prevent blinding of filter elements and are used to clarify liquids in brewing, water treatment, wine making, sugar refining, fruit juice production, and in industrial chemicals. Diatomite functional fillers are used in paints, rubber, plastics, pharmaceuticals, toothpastes, polishes, and chemicals where performance is improved by the unique properties of diatomite.
Dichlorine Monoxide, Hypochlorous Acid, and Hypochlorites
Authors: Wojtowicz John A.
Published: July 2004

The hydrolysis of chlorine gives rise to a pH‐dependent complex system involving no less than six equilibria in which the oxidizing power of the parent element is preserved in hypochlorous acid, chlorine monoxide, and hypochlorite ion. The physical and chemical aspects of this unique family of compounds, including organic and other nonmetal hypochlorites, are outlined, their preparation and manufacturing processes are surveyed, and important uses are cited. Corrosion problems and potential hazards in handling and use of these compounds are also discussed. Hypochlorous acid is the active biocidal agent when hypochlorites are employed in disinfection and sanitation. It is an intermediate in the manufacture of hypochlorites, chloramines, and chlorohydrins. A process for production of HOCl in concentrations as high as 60% has been developed. The commercially important hypochlorites are Ca(OCl)2, NaOCl solution, LiOCl, chlorinated trisodium phosphate, and to a lesser extent hemibasic Ca(OCl)2and bleaching powder. They are used primarily in sanitation and bleaching applications. The most important solid hypochlorite is Ca(OCl)2, which along with lithium hypochlorite is used mainly for swimming pool and spa sanitation. Several new processes for manufacture of Ca(OCl)2are described. Continued research interest involves use of hypochlorites for selective epoxidation, oxidation, and chlorination, and use of chlorine monoxide as a highly selective agent for aromatic ring and side‐chain chlorination.
Dietary Fiber
Authors: Lewis B. A.
Published: July 2004

Dietary fiber is a complex mixture of nondigestible polysaccharides and lignin, the exact composition depends on the plant or other food source, maturity, growing conditions, and processing. Plant cell wall polysaccharides are extensively fermented by the microbial enzymes in the lower digestive tract. The particle size and shape, density, crystallinity, water‐holding capacity, and the level and type of dietary fiber affect the rate of passage of the digests through the digestive tract. Dietary fiber itself and the microbial fermentation in the colon give rise to various beneficial physiological effects. Dietary sources of soluble and insoluble fiber and their properties and methods for analysis are summarized.
Dimer Acids
Authors: Breuer Thomas E.
Published: July 2004

Dimerization of unsaturated fatty acids occurs by self‐condensation, reaction with acrylic acid, or reaction with carbon monoxide. The physical properties of the resultant di‐(or poly‐) carboxylic acid species are listed for a few common cases. The reactions, catalysts, conditions, and equipment used for synthesis and manufacture are discussed. Analytical methods that may be used in characterization of these materials are covered with some evaluation of alternative methods. Since some use of these materials is made in food contact applications, a review of toxicity and safety and handling aspects is included. The uses of these materials are quite varied, although the majority of them involve reactive or nonreactive polyamides being made from them. Bibliographical references are included for those seeking more detail on the history, production, or use of these products.
Dimensional Analysis
Authors: Chen Wai‐Kai
Published: July 2004

Dimensional analysis provides procedures of judicious grouping of variables associated with a physical phenomenon to form dimensionless products of these variables. These products may be used more easily to determine experimentally the equation describing the physical phenomenon. Optimization procedures are outlined to simplify these products.
Dimethylacetamide
Authors: Watts J. C. , Larson P. A.
Published: July 2004

Dimethylacetamide, DMAC, mol wt 87.12, CH
3
CON (CH
3
)
2
, is a colorless, high boiling polar solvent. DMAC is a good solvent for a wide range of organic and inorganic compounds. The polar nature of DMAC enables it to act as a combined solvent and reaction catalyst, often producing high yields in short time periods. The chemical reactions of DMAC are typical of those of disubstituted amides. Dimethylacetamide can be produced by the reaction of acetic acid and dimethylamine, or by the reaction of acetic anhydride and dimethylamine. DMAC is capable of producing systemic injury, principally cumulative damage to the liver and kidney, when repeatedly inhaled or absorbed through the skin. The uses of dimethylacetamide are very similar to those for dimethylformamide.

DMAC is used where higher temperatures are needed for solution of resins as deactivation of chemical reaction.
Fluorine Compounds, Organic, Direct Fluorination
Authors: Lagow Richard J.
Published: July 2004

The development, methodology, and applications of direct fluorination technology to produce organofluorine compounds and fluorocarbon polymers is discussed in detail, including historic difficulties with direct fluorination. Techniques such as use of metal fluorides as an alternative to direct fluorination and the use of hydrogen fluoride electrochemical cell methods to affect direct fluorination are covered. The thermochemistry and kinetic control of direct fluorination are discussed. Fluorocarbon materials such as polytetrafluoroethylene and polycarbon monofluoride and their excellent high temperature properties are described. The experimental techniques that have led to the successful control of direct fluorination are described as are modern direct fluorination methods now practiced on a commercial scale by 3M Co. and Exfluor Research Corp. Examples of important direct fluorination processes such as synthesis of simple and complex organic molecules, new fluorocarbon polymers from hydrocarbon polymers, new polymeric materials with inert surfaces produced by surface fluorination, and technology for blow‐molding polymeric objects during fluorination are discussed.
Dispersants
Authors: van den Haak Henk J. W.
Published: July 2004

Dispersants are compounds that are used to maintain particles suspended in a liquid medium, either water or an organic solvent. They can prevent or delay flocculation of the particles by providing repulsive forces, counteracting the van der Waals attraction. This attraction occurs through electrostatic or steric stabilization or through a combination of these mechanisms, electrosteric stabilization.

Unlike classical dispersants, which are usually random polymers, modern dispersants consist of an anchoring section, which adheres to the particle surface, and a soluble section, which builds a protective shell around the particle. They can have different architectures: AB dispersants, AB‐diblock polymers, ABA‐ or ABC‐triblock polymers, and comb polymers. Syntheses of such architectures are discussed.

Dispersants have some similarity, but also some clear differences, with other materials, like surfactants, chelants, precipitation inhibitors, and flocculants.

Dispersants have numerous applications. They are used, among others, in cooling and heating water applications, in geothermal fluids, seawater distillation and reverse osmosis, in oilfield and mineral processing, in cements, asphalt, caulks, sealants and roof coatings, in detergents and cleaners, and in paints and printing inks.
Powders, Handling, Dispersion of Powders In Liquids
Authors: Nelson Ralph D.
Published: July 2004

This article explains the fundamental principles and practical aspects of the three steps in making a good dispersion: wetting the dry powder into the liquid, breaking up the wetted clumps, and preventing reagglomeration of the dispersed particles. It describes a variety of techniques for wetting powders into liquids of low, medium, and high viscosity, noting the design elements that provide effective operation. Simple equations illustrate how particle attractions and repulsions are related to basic physical forces and how the forces may be modified by changes in the chemical environment or by adsorption of dispersants. Several unusual methods of stabilizing dispersions are noted. Finally there is a brief section on evaluating the degree of dispersion, with reference to numerous standard methods, guidance for selecting a method appropriate to the need, and warnings of difficulties that limit the application of the methods.
Distillation, Azeotropic, and Extractive
Authors: Doherty Michael F. , Knapp Jeffrey P.
Published: July 2004

Many industrial processes depend on efficient methods for separating azeotropic, close‐boiling, or other low relative volatility mixtures. Ordinary distillation is typically either uneconomical or impossible in these cases. However, by adding specially chosen separating agents, the separation can generally be accomplished. The principal distillation‐based techniques employed for separating such mixtures are discussed: extractive or homogeneous azeotropic distillation, where a completely miscible liquid separating agent is added to alter the relative volatilities; heterogeneous azeotropic distillation, where the agent, known as the entrainer, forms one or more azeotropes and causes immiscibility; distillation in the presence of ionic salts that alter the relative volatilities of the components; and pressure‐swing distillation, wherein some azeotropes can be circumvented using a series of columns operating at different pressures. Residue curve maps, material balance lines, and column sequences are given for several example systems. Methods for identifying feasible separating agents are also discussed.
Distillation
Authors: Fair James R.
Published: July 2004

Distillation is the most widely used industrial method for separating liquid mixtures into their constituents. In chemical plants and petroleum refineries, distillations are normally carried out in vertical columns containing devices for bringing the flowing liquid mixture into intimate contact with a flowing vapor mixture that is generated by partial vaporization of the liquid. This article covers the fundamental physical and mathematical relationships that are needed for the design of new distillation columns as well as the analysis of existing columns.

The article is divided into four main topics: vapor‐liquid equilibria; distillation processes; distillation columns, both plate and packed; and distillation as a separation method. Minor divisions include such special topics as steam distillation, molecular distillation, distillation literature sources, and economics. Sufficient information is given to enable the user to carry out preliminary designs of a variety of systems, and guidance is provided for cases where additional resources might be needed.
Diuretic Agents
Authors: Cervoni Peter , Chan Peter S.
Published: July 2004

Diuretics are agents that increase urine output or flow. The effects of diuretic agents on electrolyte and water excretion in the kidney for the treatment of edema, congestive heart failure, ascites, and hypertension are reviewed. The structure and function of the kidney in the formation of urine are presented using the functional unit of the kidney, the nephron. The various sites where absorption, secretion, and the passive and active transport of water and electrolytes alter the composition of the glomerular filtrate from Bowman's capsule as it passes through the lumen of the nephron to the collecting ducts on its way to becoming urine are described. Diuretics are classified as low ceiling, high ceiling (loop), and potassium‐sparing diuretics, natriuretic peptides, atrial natriuretic peptides, atrial natriuretic peptide potentiators, osmotic diuretics, carbonic anhydrase inhibitors, methylxanthines, organomercurials, and aquaretics. The pharmacology, mechanisms or site of action in the nephron, and clinical effectiveness are discussed. Included is a discussion of the risk factors and side effects of diuretic agents.
Driers and Metallic Soaps
Authors: Landau Marvin
Published: July 2004

This article briefly outlines the evolution of metal soaps over the years from an art form to a reliable quality raw material. Methods of manufacture and the analytical tests utilized to ensure specificity of properties are described. Also included are tables indicating the volume of the various carboxylates manufactured and figures on the individual metals produced. A general description of the health and safety factors associated with these products is provided.

In application the specific metals and the attributes they provide are stated. Emphasis is placed on their use as driers for paint and printing inks as well as heat stabilizers and lubricants in plastics. Governmental legislation responding to environmental pressures has promoted the development of new technologies, yet metal soaps still remain an integral ingredient in coatings.
Drying
Authors: McCormick Paul Y. , Mujumdar Arun S.
Published: July 2004

Drying is an operation in which volatile liquids are separated from solids, slurries, and solutions to yield solid products. Drying mechanisms and processes, including psychometry, heat‐ and mass‐transfer principles, and a description of liquid and vapor flow encountered during drying are discussed. In freeze drying (lyophilization), wet material is cooled to freeze the liquid and vaporization occurs by sublimation.

Industrial dryers may be broadly classified according to the method of heat transfer as being either direct‐heat or indirect‐heat dryers. The types of dryers employed in the chemical industry, which may also be classified as batch or continuous, are described. Conventional, radiant, dielectric, and microwave heat sources are discussed as are emission control and energy usage of the various dryer types.
Dyes, Natural
Authors: Cofrancesco A. J.
Published: July 2004

With Perkin's syntheses of Mauve in 1856, the age‐old usage of natural dyes for textiles and foods greatly diminished. However, scientific interest in natural dyes continued. In 1868, the first laboratory synthesis of a natural dye, alizarin, was accomplished, followed by the manufacture of the dye. Later, indigotin was synthesized and ultimately manufactured. The structure of many other natural dyes was determined and verified by synthesis: anthraquinones, naphthoquinones, flavones, anthocyaniddins, and others. In the field of anthraquinones, some remarkable discoveries were reported: laccaic acid was shown to be a mixture of acids, and the wrong structure had been assigned to carminic and kermisic acid. The correct structure of the latter was established using the newly developed regiospecific method of synthesis. The structure of Tyrian Purple was determined and the dye synthesized. Much later, the precursors of the dye were isolated and identified.

Since the early 1970s there has been a renewal of interest in natural dyes for use as food colorants. This was prompted mainly by FDA's deletion of certain synthetic dyes used for coloring foods. Some natural dyes are on FDA's list of approved dyes for coloring foods. However, their range of color is limited, so that other sources of natural dyes have been investigated. Among these was the red beet whose color is due primarily to a red dye and a small amount of a yellow dye. Both were isolated and synthesized and found to have unique chemical structures. By a suitable modification of the chlorophyll molecule, a useful food dye has been obtained.
Dyes and Dye Intermediates
Authors: Gregory Peter
Published: July 2004

The chemistry, technology, and applications of dyes and dye intermediates are discussed. Dyes are classified both by chemical structure and usage, and dye nomenclature is explained. The more important dye classes, such as azo dyes, are covered in detail. For example, azo/hydrazone tautomerism, which is of vital importance both theoretically and commercially, is covered. Dye intermediates are discussed in depth. These fall conveniently into aromatic carbocyclic intermediates and aromatic heterocyclic intermediates. The chemistry of these systems is discussed, such as electrophilic and nucleophilic substitution, and the different synthetic strategies for the carbocyclic and heterocyclic intermediates exemplified. The unit processes, such as nitration and sulfonation, are discussed in some detail. Equipment and manufacture of dyes and dye intermediates are dealt with, as are economic aspects. Health and safety aspects, including toxicology and registration of dyes, and environmental factors, such as treatment of dye effluent, are also covered.
Dyes, Anthraquinone
Authors: Hattori Makoto
Published: July 2004

The history and current situation of the anthraquinone dye industry, and basic chemistry of anthraquinone compounds (color and structure, and general method of synthesis) are discussed. The manufacturing processes of key intermediates are illustrated both on the basis of industrial importance and advances in research and development. Emphasis is placed on process improvements in view of environmental issues.

The properties and the preparation of anthraquinone dyes are discussed according to dye type: reactive dyes (bromamine acid derivatives with sulfatoethylsulfonyl, chlorotriazine, and other heterocyclic functional group), disperse dyes (1‐amino‐4‐hydroxy‐anthraquinones, 1,4‐diaminoanthraquinone‐2,3‐dicarboxyimides, 1,4,5,8‐substituted anthraquinones, 1,4‐diaminoanthraquinones, andN‐substituted‐1‐amino‐4‐hydroxyanthraquinones), acid dyes (bromamine acid derivatives and quinizarin derivatives), vat dyes (benzanthrones, indanthrones, anthrimides, anthrimidocarbazoles, acylaminoanthraquinones, anthraquinoneazoles, anthraquinone acridones, anthrapyrimidines, and other highly condensed ring systems), and mordant dyes. Advances in functional dyes related to the electronics industry are also presented. Health and safety information is presented.
Dyes, Environmental Chemistry
Authors: Freeman Harold S. , Reife Abraham
Published: July 2004

Few would argue against the suggestion thatcoloris the number one factor in our decision to purchase a particular item, whether that item is an article of clothing, an automobile, or a dish of gelatin in the salad section of a cafeteria. While each of the aforementioned items contains a synthetic dye, extremely few of us are aware of what has taken place behind the scenes to ensure the safety of workers and consumers who are exposed to synthetic dyes. In some cases, the companies involved in the manufacture or use of dyes have not only been required by regulatory agencies to remove unsafe products from the marketplace but also to discontinue a manufacturing practice deemed unsafe. With the latter point in mind, this article covers recent developments associated with the environmental chemistry of dyes in industrial operations. Emphasis is placed on investigations pertaining to effluent treatment methods, pollution prevention, and product stewardship. It is anticipated that the contents of this chapter will prove helpful in the design of environmentally friendly dyes and in training students and other future workers in this important field.
Dyes, Sensitizing
Authors: Sturmer David M.
Published: July 2004

Spectral sensitizing dyes extend the responses of imaging materials to blue, green, red, and near infrared wavelengths. The most useful classes of dyes for photographic (silver halide) imaging are cyanine and merocyanine dyes, which provide excellent spectral sensitizing efficiencies, highly color‐selective (narrow, aggregated) absorption bands, and suitable solubility for handling during manufacturing and photographic development. Extensive industrial libraries of these compounds provide well‐tested synthetic pathways that are useful in tailoring dye structures for other applications. Electrophotography utilizes thiapyrylium dyes, squaraine dyes (analogs of merocyanines), or phthalocyanines to spectrally sensitize photohole conduction in colorless organic polymers. Red and infrared spectrally sensitized chemical reactions in medicine (eg, photodynamic therapy) use long‐wavelength dyes of the merocyanine, phthalocyanine, and hematoporphyrin classes. Spectral sensitizers from several dye classes either sensitize photochemical reactions or cause material degradation, especially those that interact to give high yields of singlet oxygen.
Electroseparations, Electrodialysis
Authors: McRae Wayne A.
Published: July 2004

Electrodialysis, a process in which ions are moved across a membrane from one solution to another under the influence of an electric current, is primariy used in the production of potable and ultrapure water. This electroseparation process is also often employed in hybrid processes to remove electrolytic and other components from seawater, industrial effluents, or other water sources. Electrodialysis uses direct current, metal electrodes and highly ion‐selective membranes. The membranes are composed of ion‐exchange resin materials.
Packaging, Electronic Materials
Authors: Pecht Michael , Prabhu Asohk
Published: July 2004

One of the largest and most pervasive industries, the electronics industry has rapidly progressed in response to the customers' demands for diverse functions, lower costs, and higher performance and reliability. This article presents an overview, along with their important characteristics and properties, of the key materials used in electronics. Included in the discussion are semiconductor, substrate, attachment, case, lead, solder, metallization, wire, tape‐automated bonding, printed wire board, conformal coating, connector, and cable and flex circuit materials.
Conducting Polymers
Authors: Foot Peter J. S. , Kaiser Alan B.
Published: July 2004

This article gives an overview of the field of electrically conducting organic polymers. The first major section describes the synthesis of the various types of conjugated conducting polymer as well as conducting polymer blends and composites. This is followed by a discussion of the redox doping required to form charge carriers, the optical properties of the polymers, and the electrical conduction properties of metallic and semiconducting polymers. A short section is devoted to the stability of different conducting polymers. The final section outlines some of the principal applications of these polymers, including electromagnetic shielding and charge dissipation, corrosion‐inhibiting paints, composite materials, charge‐storage batteries, actuators, chemical and biochemical sensors, gas separation membranes, electrochromism, polymer LEDs, laser diodes and photovoltaic cells, and plastic electronics.
Electrophoresis
Authors: Rudge Scott
Published: July 2004

Electrophoresis is a separation technique that is most often applied to the analysis of biological and other polymeric samples. The principles, modes of operation, separation matrices, detection techniques, and equipment for the various electrophoresis techniques are presented. The three principal modes of electrophoresis, zone electrophoresis, isoelectric focusing, and isotachophoresis, are discussed, as are the advantages of the principal matrices in which electrophoresis is performed, including agarose, polyacrylamide, paper, capillaries, and flowing buffers. Specific examples of techniques such as immunochemical reaction, two‐dimensional techniques, and blotting are given.
Electronic Materials
Authors: Yablonovitch Eli
Published: July 2004

Electronic materials are formed primarily from exquisitely pure Group 13, 14, and 15 (III, IV, and V) elements and alloys. These semiconductor crystals can be regarded as giant covalent molecules having weak electron‐atom interactions that result in long‐lived excited states. Historically germanium and silicon, and more recently the III‐V semiconductors, have been utilized. The progress in solid‐state electronics has been paced by the ability to produce ultrapure materials and to control the chemical bonding of these materials, particularly at surfaces and interfaces. Techniques such as molecular beam epitaxy and organometallic chemical vapor deposition are employed in the fabrication of these materials.
Elfamycins
Authors: Maehr H.
Published: July 2004

The elfamycins are so named because they exhibit antimicrobial activity through the inhibition of protein biosynthesis via binding to theelongationfactor Tu. Known elfamycins include aurodox, C44H62N2O12; kirromycin, C43H60N2O12; azdimycin, efrotomycin, C59H88N2O20; dihydromocimycin, C43H62N2O12; heneicomycin, C44H62N2O11; kirrothricin, C44H64N2O10; factumycin, C44H62N2O10; MSD A63A, L681,217, C36H53N1O10; SB22484, factor 3, C41H56N2O11; SB22484, factor 4, C42H58N2O11; phenelfamycin A, C51H71N1O15; phenelfamycin B, C61H71N1O15; phenelfamycin C, C58H83N1O18; phenelfamycin D, C58H83N1O18; phenelfamycin E, C65H95N1O21; phenelfamycin F, C65H95N1O21; unphenelfamycin, C43H65N1O14; LL‐E19020α, C65H95N1O21; LL‐E19020β, C65H95N1O21; UK‐69,753, C58H86N2O18; andN‐demethylefrotomycin, C58H86N2O20. These antibiotics are distinguished by low mammalian toxicity, narrow‐range antimicrobial activity, and positive effects on feed utilization and growth promotion in farm animals. Elfamycins are natural products. Aurodox and efrotomycin have been synthesized chemically. Elfamycins are slightly acidic and soluble in most polar organic solvents, and the alkali and ammonium salts are water‐soluble. Elfamycins block bacterial protein biosynthesis at the level of elongation factor Tu (EF‐Tu). Elfamycins have similarin vitroantimicrobial spectra and the activity againstMoraxella, Pasteurella, Yersinia, Haemophilus, Streptococcus, Corynebacterium,andNeisseriaappears to be common. Elfamycins, in general, enhance the growth of farm animals. Efrotomycin is being developed as a growth‐promoting agent for swine. The potential usefulness of elfamycins as growth promotors and feed‐conversion enhancers is now generally recognized. Low original fermentation yields and difficulties in yield improvements discouraged early attempts to develop aurodox and mocimycin (kirromycin) commercially. A development program for efrotomycin, however, is ongoing. Some of the newer elfamycins, such as the LL‐E19020 pair, are considerably more active growth promotors than aurodox or mocimycin, pointing toward a second generation of elfamycins.
Energy Management
Authors: Steinmeyer Dan
Published: July 2004

Chemical production uses approximately 20% of industrial energy. Energy costs are split roughly equally between electricity, fuel, and feedstock. Long‐term energy efficiency improvement is driven by broad technological progress, eg, computer simulation and better alloys for gas turbines. The measure of value for an energy flow is the fraction that can be converted to work. A focus on work potential defines what is theoretically possible and pinpoints losses. The biggest loss typically occurs in combustion.

The steam system is the integrating energy system in most chemical plants. Two components are steam turbines, for which higher efficiency is the goal, and steam traps for which the goal is higher reliability. The other energy systems are electrical, cooling water, and refrigeration. The largest portion of the electricity used in a chemical plant is for electric motor drives for pumps and compressors. The principal concern for cooling water systems is that water chemistry be controlled to avoid corrosion and fowling.

Energy management concerns the tradeoff between capital and energy costs throughout process areas such as distillation, drying, evaporation, and insulation. Energy efficiency offers a unique opportunity for continuous improvement because of the ease of measurement.
Engineering Thermoplastics
Authors: Garbassi Fabio , Po Riccardo
Published: July 2004

The aim of this article is to provide a first key of access to engineering polymers. For each of the materials reported, we develop a short history; the chemical structure, CAS Registry Number of the neat resin; the industrial production methods; physical, thermal, mechanical, electrical, and chemical properties; processing technologies; and finally their main applications are discussed. Because property values can vary greatly, representative figures are reported mostly from the commercial data sheets compiled by producers; these data are available online and are continuously updated.

The following polymers are considered: cyclic olefin copolymers, syndiotactic polystyrene, acetal resins (polyoxymethylene), polyester resins [ie, poly(ethylene terephthalate), poly(butylene terephthalate), and poly(ethylene naphthalate), polyarylates, liquid‐crystal polymers, poly(phenylene ether), polycarbonate, aliphatic and aromatic polyketones, acrylic resins, poly(phenylene sulfide), polysulfones, styrene copolymers, aliphatic and aromatic polyamide resins, polyimides, polyamide imide, polyphthalamide, polyetherimide and fluoropolymers [poly(tetrafluoroethylene), ethylene‐tetrafluoroethylene copolymers, fluorinated ethylene–propylene copolymers, perfluorovinylether–tetrafluoroethylene copolymers]. In addition to individual consideration of the materials used, some of the main properties are compared on the frame of interpolymer competition.
Enzyme Inhibitors
Authors: Whiteley Chris G.
Published: July 2004

This literature review reports on the current status of enzyme inhibition from the measurement of inhibitor parameters and enzyme–inhibitor design to enzyme engineering and homology modeling. It provides a brief introduction into the use of inhibitors from the purpose of development of new drugs to the impact of molecular engineering, nanomedicine, and nanotechnology. Computer‐assisted enzyme‐inhibitor design remains the most powerful approach for the generation of the structures of potential new drugs. There is presentation of a number of algorithms of computer software packages describing the enzyme's active site and the potential binding of inhibitor ligands. Appropriately, well‐established relationships such as QSAR–CoMFA (Quantitative Structure Activity Relationship–Comparitive Molecular Field Analysis), CoMISA (Comparative Molecular Shape Indices Analysis), and EDDFA (Electron Density‐Derived Field Analysis) are presented in order to show that fundamental biological principles are still very much in use in computer assisted design of inhibitors. This report also offers advantages and disadvantages of many, though not all, commercial software packages that have potential for use in inhibitor design. Finally, prospects are given for the use of texture mapping, evolutionary computing or genetic function algorithms in the creative design of new inhibitors and drugs.
Epinephrine and Norepinephrine
Authors: Pugsley Thomas A.
Published: July 2004

Epinephrine (E), norepinephrine (NE), and dopamine (DA) belong to a class of compounds known as catecholamines. A number of physical and chemical properties of E and NE, together with analytical techniques used to measure these amines and their metabolites, are reviewed. E was originally isolated from bovine adrenal glands; however, E and related compounds are now synthesized commercially from the starting material, catechol. The biosynthesis, storage, release, and the termination of action of catecholamines by re‐uptake into the presynaptic neuron that released the amine, plus mechanisms involved in regulating levels of amines in the nerve terminals, are reviewed. By virtue of functional and molecular biology studies, at least 15 subtypes of catecholamine receptors have been identified. In most cases, these physically distinct subtypes each have important second messengers and pharmacological consequences that are summarized. Catecholamines and related compounds exhibit a wide diversity of physiological functions, and thus are involved therapeutically in a wide range of uses both in the peripheral and central nervous system.
Esterification
Authors: Aslam Mohammad , Torrence G. Paull , Zey Edward G.
Published: July 2004

This discussion of esterification covers both the theoretical and practical implications of the technology. The kinetics and mechanism of esterification of carboxylic acids with alcohols are reviewed, along with factors affecting and methods for bringing about the completion of reaction. Several technical examples of esterification are given to demonstrate how the theory is applied. These examples include discussions of batch, continuous, and vapor‐phase processes.

Methods for synthesizing esters from other compounds, such as acid anhydrides, acid chlorides, amides, nitriles, unsaturated hydrocarbons, ethers, aldehydes, and ketones are outlined. Numerous references and techniques are described.

The process of esterification is also approached from the aspect of physical properties and characteristics. For example, a discussion on the synthesis of low, medium, and high boiling esters is given. Also, esterification techniques regarding difficulty esterifiable acids and ester interchange are described.
Esters, Organic
Authors: Sakamuri Raj
Published: July 2004

This article gives relevant information related to carboxylic esters including nomenclature, physical and chemical properties, occurrence and preparation, analysis, health and safety issues, handling regulations, and commercial uses.

Chemical reactions of esters discussed are hydrolysis (both catalyzed and uncatalyzed), transesterification, ammonolysis, aminolysis, reduction (catalytic and stoichiometric), enolate reactions, Grignard and related reactions, acyloin condensation, pyrolysis, substitution, alkylation, and rearrangement.

Analytical methods for characterization of esters including spectroscopy are presented. Aspects of health, safety, and handling of esters are discussed in relation to their reactivity, flash point, autoignition temperature, toxicity data, and permissible exposure limits.

Uses of esters in areas such as solvents, plasticizers, resins, plastics, coatings, lubricants, perfumes, flavors, cosmetics, soap, surface active agents, medicinals, herbicides, pesticides, and photoresists are described.
Hormones, Estrogens and Antiestrogens
Authors: Guo J. Z. , Hahn D. W. , Wachter M. P.
Published: July 2004

Estrogens are a group of naturally occurring steroid sex hormones which are characterized by their ability to induce estrus (ovulation) in the female mammal. This article provides a general background and update on the status of steroidal and nonsteroidal estrogens. In addition, the chemistry and clinical applications of steroidal and nonsteroidal antiestrogens, which were developed in recent years, are included. The emphasis on this area has focused on the goal of discovering synthetic antiestrogens devoid of estrogen agonist activity. Representative studies, which have attempted to delineate the mechanism of action for estrogens and antiestrogens, based on binding studies, molecular modeling strategies, or the like, have also been highlighted. An overview of the pharmacology of estrogens is presented with a particular emphasis on receptor‐mediated molecular events. Contraception, hormone replacement, and chemotherapy are the three primary therapeutic applications for estrogens. A table listing principal preparations of estrogens for hormone replacement therapy is also included.
Ethylene‐Acrylic Elastomers
Authors: Wu Yun‐Tai , McBride Edward
Published: July 2004

Ethylene–acrylic elastomers are copolymers of ethylene, methyl acrylate, and a cure site monomer. They have been commercially available for over 25 years under the trade name Vamac. A family of dipolymers is now available which does not contain the cure site monomer and is cured with peroxides. Cured compounds made from Ethylene–acrylic elastomers have an excellent combination of good heat resistance, good fluid resistance in engine oils and automatic transmission fluids, and good low temperature properties. These compounds perform well in automotive applications such as hoses, gaskets, torsional dampers, and various other parts.
Exhaust Control, Automotive
Authors: Mooney John J.
Published: July 2004

Automotive exhaust gas composition depends on the fuel, the air‐fuel ratio, and on engine type, wear, temperature, etc. Exhaust control systems must be versatile enough to oxidize unburned fuel and partial oxidation products such as carbon monoxide, yet reduce nitrogen oxides, at both engine start‐up and during sustained engine operation. Emission control systems consist of a catalytic converter for the oxidation‐reduction of exhaust gases in conjunction with a fuel ignition system and oxygen sensor to regulate the air‐fuel ratio. Exhaust for both gasoline and alternative fuels is discussed.
Expectorants, Antitussives, and Related Agents
Authors: Paul David B. , Dobberstein Robert H.
Published: July 2004

Expectorants enhance the projection of respiratory tract fluid and thus facilitate the mobilization and discharge of bronchial secretions. Stimulant expectorants increase respiratory tract secretion by a direct effect on the bronchial secretory cells, and sedative expectorants act by gastric reflex stimulation. Classes of expectorants discussed include quaiacols, volatile oils, iodides and other inorganic compounds, and miscellaneous natural products.

Mucolytics reduce the viscosity of tenacious and purulent mucus, thus facilitating removal. Some agents discussed that chemically depolymerize certain components of mucus include trypsin, other proteolytic enzymes, andcis‐4‐hydroxymethyl‐2‐iodomethyl‐1,3‐dioxolane.

Antitussives control excessive coughing. A brief description of the cough reflex is presented. Centrally active antitussives, both narcotic and nonnarcotic, as well as peripherally active antitussives are presented and discussed.
Expert Systems
Authors: Ramesh T. S.
Published: July 2004

Expert systems, or more appropriately knowledge‐based systems, are essentially computer programs that encode the expertise of human problem solvers in some well‐defined domain. A practical offshoot of the field of artificial intelligence, knowledge‐based technology has emerged as an important area of computer applications, with significant business impact on the industry. This is because knowledge‐based systems can automate problem‐solving tasks that hitherto could not be computerized by conventional, numeric modeling techniques. In the domain of chemical engineering, knowledge‐based systems have been used to automate such tasks as equipment and process design, control of complex processes, troubleshooting process operations, scheduling batch processes under uncertain conditions, and simulation of discrete event operations. This article discusses the motivations and benefits of knowledge‐based technology as applied to chemical engineering problems; the differences between knowledge‐based systems and quantitative, numerical techniques; the theoretical underpinnings of the technology; approaches to selecting, designing, and implementing knowledge‐based system applications; and some of the tools available to implement such systems. Alternatives to expert systems such as neural networks (nets) and case‐based reasoning are also briefly discussed. Throughout, the concepts are illustrated using examples from chemical engineering.