bluuebunny/crossref_metadata_2025 huggingface dataset:
Catalyst Deactivation and Regeneration
Authors: Bartholomew Calvin
Published: July 2004

This article focuses on the causes, mechanisms, prevention, modeling, and treatment (experimental and theoretical) of deactivation. The causes of deactivation are basically of three kinds: chemical, mechanical, and thermal. The five intrinsic mechanisms of catalyst decay, (1) poisoning, (2) fouling, (3) thermal degradation, (4) chemical degradation, and (5) mechanical failure, vary in their reversibility and rates of occurrence. Poisoning and thermal degradation are generally slow, irreversible processes while fouling with coke and carbon is generally rapid and reversible by regeneration with O2or H2. Catalyst deactivation is more easily prevented than cured. Poisoning by impurities can be prevented through careful purification of reactants. Carbon deposition and coking can be prevented by minimizing the formation of carbon or coke precursors through gasification, by careful design of catalysts and process conditions and by controlling reaction conditions to minimize effects of carbon and coke formation on activity. Sintering is best avoided by minimizing and controlling the temperature of reaction. Regeneration of deactivated catalysts is possible for many catalytic processes and is widely practiced.

The purpose of this article is to provide the reader with a comprehensive overview of the scientific and practical aspects of catalyst deactivation, including mechanisms of catalyst decay, prevention of deactivation, regeneration of catalysts, methods for study and treatment of catalyst decay, and deactivation kinetics. The greatest emphasis is on deactivation and regeneration of heterogeneous catalysts, although decay mechanisms of homogeneous catalysts and enzymes as well as methods of stabilizing these catalyst types are briefly addressed.
Nomenclature
Authors: Smith Peter A. S.
Published: July 2004

Names for chemical substances have developed from primitive terms based on their source, properties, or effects into an elaborate system in which names encode precise information about chemical structures. Inorganic chemistry was elaborated first, and is strongly concerned with elemental composition and ionic and oxidation states. Organic nomenclature at first followed the inorganic pattern, but diverged from it because of the importance of connectivity and isomerism in organic compounds. The present system of organic nomenclature is based on the principles of the Geneva Conference of 1892, developed and expanded by international conferences and commissions into the nomenclature recommended by the International Union of Pure and Applied Chemistry (IUPAC). The nomenclatures of inorganic, organic, and macromolecular chemistry and of biochemistry are in a continuing state of development, and new recommendations from the international bodies are published in the appropriate journals, such asPure and Applied ChemistryandBiochemistry.The rules are collected in book form at intervals.
Recycling, Nonferrous Metals
Authors: Richardson H. Wayne
Published: July 2004

Richardson, H. Wayne (Phibro‐Tech, Inc.). The methods of recycle for various nonferrous metals of economic importance are detailed. Principal metals are aluminum, copper, lead, and zinc, although cobalt, nickel, tin, and precious metals such as gold, silver, and palladium are also recycled. Types and sources of scrap and waste metal are given. Much recyclable material arises from discarded automobile parts, beverage cans, and industrial metal industry wastes. Factors that influence the decision to recycle by pyrometallurgical or hydrometallurgical means are discussed. These processes are described, including the types of furnaces employed for smelting operations and the extractants used for solvent extraction systems. Recycling of nonferrous metals is heavily dependent on the economics of using secondary metal feed rather than ore. The role of waste management is also considered. Vol. 20, pp. 1106–1126, 31 refs. to August 1995.
Feeds and Feed Additives, Nonruminant Feeds
Authors: Waldroup Park W.
Published: July 2004

Meat and eggs produced by swine and poultry in the United States contributes significantly toward meeting the nutritional requirements of the human population. The feed required to produce such a quantity of meat and eggs is considerable. Most poultry operations and some swine operations take place in intensive confinement operations. Most of the poultry production take place in vertically integrated operations. This system is not as common in the swine industry. Both swine and poultry are fed diets composed of grains such as corn or grain sorghum with soybean meal the primary protein source. Many human and industrial byproducts that would otherwise go unused are also incorporated into feed for nonruminants. Vitamins and trace minerals are added to ensure an adequate supply. Amino acids produced by fermentation or chemical synthesis are used to fortify diets, resulting in feeds with lower crude protein contnt. Nutrient requirements of swine and poultry are well reserched and nutrient composition of common ingredients has been determined. As ingredient prices change in relation to supply and demand, diet composition can be changed rapidly. There is no “best” feed composition. Animals thrive on diets composed of many different types of diets so long as the diets provide adequate levels of essential nutrients.
Nuclear Fuel Reserves
Authors: Bullen Daniel B.
Published: July 2004

The primary fuel for light‐water nuclear reactors is natural or slightly enriched (3–5%) uranium dioxide. Estimates of the world reserves of uranium resources are based on the cost of recovery for various ore types and classified as reasonably assured, estimated, or additional, speculative resources. World reactor‐related requirements are expected to increase from usage in the early 1990s through the year 2010. Additional sources of uranium are expected to come from the de‐enrichment of weapon‐grade, high enriched uranium mixed with natural uranium in an approximate 1:30 ratio.
Nucleic Acids
Authors: Rehmann Jill
Published: July 2004

Nucleic acids are essential components of all organisms. Deoxyribonucleic acids (DNA), most commonly double helical, encode the genetic information contained in living cells. Ribonucleic acids (RNA), a more diverse class of biopolymers able to adopt helical and other more complex tertiary structures, carry out a variety of intracellular functions, including transmitting the genetic message to the site of protein synthesis. Both DNA and RNA interact with a host of other molecules, eg, proteins, drugs, as well as other nucleic acids and nucleic acid constituents. The specificity of these interactions may be related to local sequence‐dependent structural variation. The structural characteristics of nucleic acids and their constituents are discussed.

Development of techniques to synthesize oligonucleotides, which are short, well‐defined sequences of DNA or RNA, provides an opportunity to study nucleic acid structure in detail. In addition, oligonucleotides have proved invaluable in analytical procedures. The unique ability of nucleic acids to bind to self‐complementary sequences has been exploited in the design of oligonucleotide probes and in antisense drug strategies. Methods for synthesizing nucleic acids and their constituents, including both unmodified and modified analogous, are discussed.
Nucleosides and Nucleotides
Authors: Suhadolnik Robert J. , Reichenbach Nancy L.
Published: July 2004

The naturally occurring nucleoside and nucleotide antibiotics exist as either theC‐ orN‐glycosides. They include ezomycin A1(C26H38N8O15S), ezomycin B1(C26H39N7O17S), ezomycin C1(C26H37N7O16S), ezomycin A2(C19H26N6O12), ezomycin B2(C19H25N5O13), ezomycin C2(C19H25N5O13), showdomycin (C9H11NO6), isoshowdomycin (C9H11NO6), maleimycin (C7H7NO3), oxazinomycin (C9H11NO7), pyrazomycin (pyrazofurin) (C9H13N3O6), formycin (C10H13N5O4), formycin B (C10H12N4O5), oxoformycin B (C10H12N4O6). These antibiotics contain a variety of purine and pyrimidine rings. The naturally occurring nucleoside/nucleotide antibiotics, which have been isolated from bacteria, fungi, blue‐green algae, and marine sponges, have proven to be useful biochemical probes in eucaryotic, procaryotic, viral, fungal, and plant systems. The purine nucleosides inhibit protein synthesis, RNA and DNA synthesis, and methyltransferases; they have antimycoplasmal, antiviral, hypotensive, antifungal, antimycobacterial, and antitumor activities and induce sporulation. The pyrimidine nucleosides inhibit protein synthesis, virus replication, RNA and DNA synthesis, and cAMP phosphodiesterase. The imidazole nucleosides inhibit nucleic acid synthesis. The diazepin nucleosides inhibit adenosine deaminase (ADA). The indole nucleosides inhibit bacteria, yeast, fungi, and viruses. TheN‐nucleotide antibiotics include agrocin 84 (C21H34N6O16P2), thuringiensin (C22H30N5O19P), phosmidosine (C16H24N7O8P), fosfadecin (C13H19N5O10P2), and fosfocytocin (C12H20N4O13P2). Thuringiensin, produced byB. thuringiensis, is a β‐exotoxin that exerts its toxic action on insects and mammals through the inhibition of RNA polymerases. Phosmidosine inhibits pore formation ofBotrytis cinereaandAspergillus niger. Fosfadecin and fosfocytocin inhibit gram‐positive and gram‐negative bacteria.
Nuts
Authors: Young Clyde T.
Published: July 2004

Nuts, hard‐shelled seeds enclosing a single edible oily kernel, are generally used for human consumption. Nuts may be consumed as shelled whole nuts or, after blanching, roasted. Roasted nuts may be either eaten or ground into nut butters. Peanuts which contain excessive levels of aflatoxin are generally extracted for peanut oil. Production processes are outlined for nut salting, defatting, and the making of peanut butter. With the exception of peanuts, most commercially important nuts are borne on trees. As a whole, nuts have high oil and protein contents and a low percentage of carbohydrate. Approximate composition in terms of amino acid, fatty acid, vitamin and carbohydrate levels are tabulated for selected nuts and nut products. Because of the high oil content of nuts, rancidity is one of the first signs of deterioration in nuts. Optimal storage conditions are discussed as are coatings and antioxidants to delay the onset of rancidity. Non‐edible uses of nuts are as a source of quick drying oils, activated charcoal, dyes, and tannins. Production data are given for the principal edible nuts: almonds, cashews, Brazil nuts, coconuts, English walnuts, filberts or hazelnuts, macadamia nuts, pecans, and pistachios.
Ocean Raw Materials
Authors: Cruickshank Michael J.
Published: July 2004

Inorganic raw materials are defined as any mineral deposit found in the marine environment. The ocean is host to a variety and quantity of inorganic raw materials equaling or surpassing the resources of these materials available on land. The mineral resources include industrial minerals, mineral sands, phosphorites, metalliferous oxides, hydrothermal metalliferous sulfides, and dissolved minerals, as well as geothermal resources, precious corals, and some algae. The resources are classified as unconsolidated, consolidated, or fluid materials which are chemically enriched in certain elements and are found in or on the seabeds of the continental shelves and ocean basins. With few exceptions these materials are similar to traditional mineral deposits on land. A significant source of minerals for sustainable recovery in the future may be ocean waters, which include nearly all the known elements in some degree of solution. Commercialization of production of dissolved minerals from seawater is limited to fresh water, magnesium, magnesium compounds, salt, bromine, and heavy water, ie, deuterium oxide. There are four basic methods of mining solid minerals: scraping the surface, excavating a pit or trench, removal through a borehole in the form of a slurry or fluid, and tunneling into the deposit. An apparently significant advantage to recovery of mineral raw materials from the marine environment is the benign effects of these activities when compared to the recovery of the same materials from land.
Recycling, Oil
Authors: Becker Donald A. , Brinkman Dennis W.
Published: July 2004

This article discusses the recycling of used petroleum oils. The term oil includes a variety of liquid or easily liquefiable, unctuous, combustible substances that are soluble in ether but not in water and that leave a greasy stain on paper or cloth. These substances can include animal, vegetable, and synthetic oils, but usually the word oil refers to a mineral oil produced from petroleum. An oil that has been used or contaminated, or both, but not consumed, can often be recycled to regain a useful material regardless of its origin. In the past, used or contaminated oil was usually considered a waste and was disposed of in a variety of ways, including incineration, road oiling, landspreading, municipal landfills, and dumping on the ground or into storm sewers. However, on account of the increased concern about pollution, the advent of periodic petroleum shortages, and increased prices for most kinds of oils and oil products, there is a strong interest in developing ways to conserve the valuable energy and resource content of these products.
Fibers, Olefin
Authors: Wust C. J. , Landoll L. M.
Published: July 2004

Olefin fibers, also known as polyolefin fibers, are synthetic fibers of growing commercial importance. Several olefin polymers are capable of forming fibers, but only polypropylene and polyethylene are of practical importance. From the first commercial application of polyethylene in automobile seat covers to multicomponent extrusion for specialty applications, olefin fibers have made a significant impact in the fiber industry. This article reviews the fiber properties, including physical, tensile, chemical, and thermal and ultraviolet stability, which make them ideally suited for these varied applications. Commercial fiber manufacturing and processing is discussed for staple fiber, continuous filament, and directly formed nonwovens. The extrusion, quench, and draw play integral roles in the development of the fiber properties. Bicomponent, high strength, and hard‐elastic fiber technology is examined. Olefin fiber consumption statistics are broken down by use.
Opioids, Endogenous
Authors: Selley Dana E. , Sim Laura J. , Childers Steven R.
Published: July 2004

Endogenous opioid peptides represent a significant class of peptide neurotransmitters in brain and peripheral tissues. They share the common property of high affinity binding to one or more of three principal types of opioid receptor, µ, δ, and κ. The endogenous opioid peptides include three classes: the enkephalins, β‐endorphin, and dynorphin. These peptides share the pentapeptide sequence of either Met‐ or Leu‐enkephalin. The peptides in each class are synthesized from high molecular weight precursors; trypsin‐like cleavage between pairs of basic amino acid residues yields intermediate and final peptide products. Each class of peptides possesses a unique regional distribution in the brain, and mediates a variety of functions, including analgesia, respiration, thermoregulation, neuroendocrine regulation, and modulation of immune cell function. Although synthesis of numerous synthetic analogues of opioid peptides have not produced analgesic drugs of practical importance, they have produced analogues with extraordinary specificity and stability which provide valuable information about the structure of opioid binding sites.
Cellulose Esters, Organic Esters
Authors: Gedon Steven , Fengi Richard
Published: July 2004

Cellulose is one of nature's most abundant structural materials, providing the primary framework of most plants. For industrial purposes cellulose is derived from two primary sources, cotton linters and wood pulp. Cellulose esters are commonly derived from natural cellulose by reaction with organic acids, anhydrides, or acid chlorides. Cellulose esters of almost any organic acid can be prepared, but because of practical limitations esters of acids containing more than four carbon atoms have not achieved commercial significance. Cellulose acetate is the most important organic ester because of its broad application in fibers and plastics; it is prepared in multi‐ton quantities with degrees of substitution (DS) ranging from that of hydrolyzed, water‐soluble monoacetates to those of fully substituted triacetate. Although cellulose acetate remains the most widely used organic ester of cellulose, its usefulness is restricted by its moisture sensitivity, limited compatibility with other synthetic resins, and relatively higher processing temperature. Cellulose esters of higher aliphatic acids, C3and C4, circumvent these shortcomings with varying degrees of success. Mixed cellulose esters containing acetate and either the propionate or butyrate moieties are produced commercially in large quantities by Eastman Chemical Co. in the United States. The properties, manufacturing methods, uses, economics, and safety of organic esters of cellulose are discussed.
Pigments, Organic
Authors: Jaffe Edward E.
Published: July 2004

The article is intended for anyone interested in organic pigments in general or specific pigment classes in particular, with references provided for greater in‐depth review of scientific and theoretical considerations. This article begins with definition, identification, and categorization of organic pigments, followed by a list of 54 commercial pigments, including methods of their preparation. Also described is the origin of color in organic compounds and the relationship between absorbed light and observed color. Technical and durability properties are described in some detail, followed by a description of pigment types, including structural formulas of representative pigments, generalized wherever appropriate. For some pigment classes tables are included to identify additional important pigments of a group. In each case, a short description of pigment attributes and shortcomings as well as applications are included. The pigment types range from the least expensive, simple pigments, to the most sophisticated, complex structures, ranging in properties from poor to excellent. The description of production and economic aspects are based on governmental statistical data and other information available in the literature, private sources and the Internet, and includes worldwide data with particular emphasis on U.S. consumption, exports, and imports. Finally, methods of pigment testing, standardization, and color measurement are briefly described. The article concludes with a brief discussion of health effects, toxicity of pigments, their effect on the ecology, and uses.
Electrochemical Processing, Organic
Authors: King Chris J. H.
Published: July 2004

The technology for electroorganic synthesis is surveyed starting with an overview of the electrochemical cells for this purpose. Cell design, electrode materials, and diapraghms are discussed as are cell current distribution and mass‐transport phenomena. Features influencing good product selectivity for specific cell designs are presented together with the various commercially available cells. Cost analysis for electroorganic synthesis is reviewed. The electroorganic processes that have been commercialized or have been pilot planted are presented.
Graphite, Specialty
Authors: Criscione J. M.
Published: July 2004

A useful form of graphite is a flexible sheet or foil. Because of graphite's stability at high temperatures, flexible foil is useful in applications requiring thermal stability in corrosive environments, eg, gaskets and valve packings, and is often used as a replacement for asbestos gaskets. Carbon–graphite foam is a prime candidate for thermal protection of new, emerging carbon–carbon aerospace reentry vehicles. Pyrolytic graphite produced in massive shapes is used for missile components, rocket nozzles, and aircraft brakes for advanced high performance aircraft. Glassy, or vitreous, carbon is a black, shiny, dense, brittle material with a vitreous or glass‐like appearance. Chemical inertness and low permeability have made glassy carbon a useful material for chemical laboratory crucibles and other vessels. Carbon and graphite paper has outstanding electrical conductivity, corrosion resistance, and moderately high strength. It is used in electrodes for electrostatic precipitators.
Oxygen
Authors: Hansel James G.
Published: July 2004

Oxygen is a key element for the existence of life on earth as well as an ingredient for a wide variety of manufacturing processes. Oxygen is produced commercially by the cryogenic separation of air into mainly oxygen and nitrogen or by vacuum swing adsorption procedures. The oxygen is transported to users primarily by pipelines as a high pressure gas or within tank trucks as a cryogenic liquid. Most oxygen is used captively. It is widely used in steel and other metal refining and fabrication industries as well as in the production of many petrochemicals and in health‐related fields. Specifications depend on use.

In some cases oxygen is used as a replacement for air in a process; in other applications air is enriched in oxygen. In many applications, reducing or eliminating the nitrogen normally present in the air typically increases the combustion temperature, increases the yield of product formed, and reduces the volume of waste gas to be treated.
Oxygen‐Generation Systems
Authors: Mausteller J. Wilson
Published: July 2004

Oxygen generation from oxygen‐containing compounds is used for systems for respiratory support wherever sufficient oxygen from air is unavailable. Use is made in submarines and spacecraft as well as in breathing apparatus. Additionally these systems provide emergency oxygen supplies for aircraft in the case of decompression and for bomb shelters. Materials composition and reactions, system design, and oxygen gas purity are presented.

Discussed herein are systems based on chlorates, perchlorates, peroxides, and superoxides. Whereas alkali metal salts of these anions all produce oxygen, the peroxides and superoxides also provide a mechanism for carbon dioxide absorption. Most commercial production centers around large chlorate candles for use in submarines and use of potassium superoxide in portable breathing apparatus and emergency aircraft oxygen supply.
Fluorine Compounds, Inorganic, Oxygen
Authors: Solomon I. J. , Shreeve Jean'ne M.
Published: July 2004

Oxygen difluoride is the most stable binary compound of oxygen and fluorine. It is mainly a laboratory chemical. Dioxygen difluoride is unstable and difficult to purify, but has found some application in the conversion of uranium oxides to UF6and as a recovery agent for actinides from nuclear wastes. Physical and chemical properties are given.
Ozone
Authors: Wojtowicz J. A.
Published: July 2004

This article discusses solubility, absorptivity, explosivity, as well as thermodynamic, spectral, structural, and other physical properties of ozone in the gaseous, liquid, and solid states; it reviews both organic and inorganic chemistry and offers various analytical methods for determining ozone in the solution and the gas phase. It examines, from a mechanistic viewpoint, not only the thermal and photochemical decomposition of gaseous and aqueous ozone, but also its generation, including gas preparation, electrical requirements and characteristics, efficiency, costs, and design. In addition, the article investigates atmospheric ozone formation in the troposphere and the stratosphere from the standpoint of photochemical smog, surveying the effect of natural and anthropogenic contaminants on ozone decomposition. Finally, the article considers numerous health and safety issues, including such topics as the depletion of ozone layer, environmental and human exposure, and ozone disinfection by‐products.

Ozone can be used in drinking water, high purity water for bottling and canning plants, as well as the pharmaceutical and electronics industry; it can be used to bleach textiles and natural products, to control industrial wastewater pollution and sewage, to disinfect wastewater as well as water for large aquariums and shrimp hatcheries, to treat process water, swimming pools, and spas; it can also be used for pulp bleaching, organic synthesis, medical applications, and food preservation. Vol. 17, pp. 953–994, 168 refs. to May 1995.
Paper
Authors: Lyne M. Bruce
Published: July 2004

Paper consists of sheet materials comprised of bonded small discrete fibers. The fibers usually are cellulosic and are held together by hydrogen bonds. Paperboard differs from paper in that it generally is thicker, heavier, and less flexible than conventional paper. More than 95% of the base materials used in paper and board manufacture is fibrous. Whereas a large percentage originates from wood, the filler contents of some grades of paper approach 30%. There are many different manufacturing processes involved in the conversion of wood to pulp. These range from mechanical to chemical processes. Many combinations of mechanical and chemical methods are also employed.

In modern practice, as much water as is compatible with efficient machine operation is recycled. The loss of fibers and inert furnish components, particularly clay, has been greatly reduced. Fiber losses, however, still occur into the white water, and greater economy of operation may be achieved if these fibers could be recovered. If general recovery methods are operated efficiently, the net fiber loss can be less than 1%. Totally closed mill white water systems are possible.

Physical and chemical properties, manufacture and processing, sheet preparation, economic aspects, analytical test methods, environmental issues, and uses are discussed.
Patents and Trade Secrets
Authors: Gresens John J.
Published: July 2004

This article provides a basic, step‐by‐step approach to the practice and management of patents and trade secrets. The significance of aggressive patent and trade secret protection to the economic well‐being of a business or organization should not be underestimated. Patents and trade secrets are protected by securing rights to ideas and the application of ideas which have commercial worth. The grant of rights in patents and trade secrets is based on an appreciation of development, advancement, and invention that will stimulate innovation by advancing technology. Both patent and trade secret rights are supported by the policies and laws of the United States. This article provides a hands‐on tool, including practice tips, check lists, and a compendium of basics on patent and trade secret management.
Fluorine‐Containing Polymers, Perfluorinated Ethylene‐Propylene Copolymers
Authors: Gangal Subhash V.
Published: July 2004

Perfluorinated ethylenepropylene (FEP) is a copolymer of tetrafluoroethylene (TFE) and hexafluoropropylene (HFP). It retains most of the desirable characteristics of polytetrafluoroethylene (PTFE) but with a melt viscosity low enough for conventional melt processing. The introduction of hexafluoropropylene lowers the melting point of PTFE from 327C to about 260C. The lower melt viscosity allows melt extrusion of wire insulation of longer continuous lengths than the batchwise paste extrusion of PTFE and the injection molding of intricate shaped parts. This polymer has a combination of properties that make it useful in applications that require chemical inertness, excellent dielectric properties, good weatherability, antistick properties, low coefficient of friction, and performance in temperature extremes. As a thermoplastic, it can be processed by extrusion and compression, injection, and blow molding. Films can be heat bonded and sealed, vacuum formed, and laminated to various substrates.

Aqueous and nonaqueous dispersion polymerizations are the most convenient routes to producing these copolymers. The polymerization conditions are similar to those of TFE homopolymer dispersion polymerization. The optimal composition of the copolymer requires that the mechanical properties are retained in the usable range and that the melt viscosity is low enough for easy melt processing.
Fluorine‐Containing Polymers, Perfluoroepoxides
Authors: Resnick Paul R.
Published: July 2004

Perfluorinated epoxides have been prepared primarily by the oxidation of the parent fluoroolefin. They readily react with nucleophiles to give ring‐opened products and oligomers. Reactions with electrophiles also result in the opening of the epoxide ring. Perfluoroepoxides which contain a CF2linkage in the epoxide ring undergo smooth decomposition at modest temperatures to give difluorocarbene.

Hexafluoropropylene epoxide is the most important of this class of compounds. Its primary use is as an intermediate for the preparation of a number of commercially important trifluorovinyl ethers. The compound also serves as a starting material for the preparation of hexafluoroacetone and a series of oligomers which have been converted to a variety of stable liquids.

The chemistry of other perfluorinated epoxides, as well as that of epoxides containing small amounts of other halogen and hydrogen, has been explored. With the possible exception of the epoxides of perfluoroallyl chloride and tetrafluoroethylene the work is primarily of scientific and academic interest. The reactions are almost entirely analogous to those of hexafluoropropylene epoxide.
Pesticides
Authors: Leng Marguerite L.
Published: July 2004

A pesticide is any substance or mixture of substances used to control living organisms that cause damage or economic loss, or transmit or produce disease, including such animals as insects or mice, unwanted plants, microorganisms such as those causing plant diseases, or viruses. Early pesticides were simple, often toxic inorganic compounds having a broad spectrum of activity, and often applied indiscriminately at high rates. Newer crop protection agents are generally complex organic chemicals, which may bind to a specific enzyme recoptor. Some commercial pesticides are biological agents.

Pesticide use in the United States is 57% herbicides, 23% insecticides, 12% fungicides, and 8% other, including household disinfectants, repellents, rodenticides, etc. About 90% of pesticides are produced by 20 companies, 9 located in Europe, 6 in the United States, and 5 in Japan. All pesticides produced and used in the United States must be reviewed and registered by the U.S. EPA. Extensive studies on chemistry, residues in treated food commodities, environmental fate, and toxicity to laboratory animals and wildlife, to demonstrate that proposed uses do not cause undue harm to humans or the environment, are required. The estimated cost for developing a new pesticide is\documentclass{article}\usepackage{amssymb}\pagestyle{empty}\begin{document}${{\$}70\times 10^{6}}$\end{document}over 10–12 years. Problems for the agrochemical industry and for government regulators include the lack of harmonization of study requirements in developed countries, and public perception that pesticides are not adequately tested and are inherently harmful.
Petroleum Resources
Authors: Drew Lawrence J.
Published: July 2004

The petroleum resources considered here are those liquid crude oils that can be produced by conventional production technologies and, to some extent, those unconventional sources of crude oils that can be captured and converted into conventional sources in the near term by advancing production technologies. Most of the large volume of these crude oils that are consumed in the world are produced from only a small fraction of the oil fields that have been discovered. By far the largest concentration of these reserves is located in Saudi Arabia, the United Arab Emirates, and Kuwait. More than one‐half of the world's proved reserves are contained in 51 out of the more than 20,000 fields that have been discovered. Proved reserves in countries with mature producing provinces such as the United States have been declining. However, the United States remained the second largest producer in the world in 1992. The former Soviet Union was the largest producer of crude oil. In terms of the balance of consumption vs production, the Eastern Hemisphere produces 71% and consumes 65% of the world's crude oil. Most of the surplus 6% is consumed in the United States. In terms of regional production and consumption, the Middle Eastern region produces five times more crude oil than it consumes. The counterpart to this imbalance is in OECD Europe, where consumption is three times production.

The world is not running out of crude oil in the ground. Important technological and economic problems, however, need to be solved so that these resources can be converted to usable reserves.
Pharmacodynamics
Authors: Triggle David J.
Published: July 2004

Pharmacodynamics is the study of drug action primarily in terms of drug structure, sites of action, mechanisms of drug–target interaction, as well as the biochemical and physiological consequences of the action of the drug. Pharmacodynamics may be regarded as one branch of the larger discipline of pharmacology relating to all aspects of drug action, from isolation, characterization, to pharmacokinetic, therapeutic, and toxicologic descriptions.

A principal concern of pharmacodynamics is the interaction of drugs with specific receptors. Increasingly, these studies are quantitative ones relating structural and genetic information. Such studies include the description of binding interactions, the definition of structure–activity relationships, the elucidation of transduction mechanisms by which receptor signals are translated into response, and the mechanisms by which receptors are regulated through chronic drug and hormone action as well as during disease processes. These considerations of pharmacodynamics are exerted at both preclinical and clinical states.
Pharmaceuticals, Chiral
Authors: Witiak Donald T. , Hopper Allen T.
Published: July 2004

Enantiomers differ in absorption rates across membranes, bind with different affinities to plasma proteins, undergo alternative metabolic and detoxification processes and possess distinct binding interactions with their enzyme or receptor targets. Homochiral pharmaceuticals generally display both increased potency and decreased side effects when compared with their racemates. The pharmaceutical industry is taking advantage of the potential financial benefits of homochiral drugs by reinvestigating the enantiomers of chiral racemic drugs and patenting new pharmacological data and production technology for single enantiomers. Differences in the biological activities, pharmacodynamics, pharmacokinetics and metabolism of enantiomeric pairs are briefly reviewed for the following drug classes: antihypertensive agents including β‐blockers, calcium channel blockers, and angiotensin converting enzyme inhibitors; nonsteroidal antiinflammatory drugs; central nervous system depressant drugs; antimicrobial drugs; opioid analgesic drugs; anticoagulant drugs; neurotransmitters; antineoplastic drugs; and peptidomimetic agents. Methods for the preparation of homochiral drugs, determination of absolute configuration and measurement of enantiomeric purity are discussed.
Regulatory Agencies, Pharmaceuticals and Cosmetics
Authors: L. Yingling Gary , Onel Suzan
Published: July 2004

The Food and Drug Administration (FDA) is the primary federal scientific and regulatory government agency that monitors drug, biologic, medical device, food, veterinary and cosmetic products. FDA is organized into five distinct centers, each with its own rules and regulations. This article discusses FDA's traditional regulatory mission of consumer protection and how its decisional processes have changed over time as a result of the explosion of advances within analytical chemistry and toxicology. Because no compound is completely safe, FDA must regularly assess the intended use of a product and whether the level of risk is acceptable. The article also summarizes the legislation that sets the boundaries of FDA's authority and lays out the administration's organization and responsibilities.
Pharmaceuticals
Authors: Zanowiak Paul
Published: July 2004

The many types of drug product dosage forms are present. Contemporary forms are discussed, as are technologies of design and manufacture to deliver safe and effective therapeutic responses each time administered. U.S. pharmaceutical organizations, including those that involve the practice of pharmacy, pharmaceutical research and manufacture, licensure, and education are identified and the economic aspects of the industry discussed.

Bioavailability, bioequivalence, and pharmacokinetics are defined, and drug delivery systems that are designed to achieve appropriate drug therapy, such as sustained action dosage forms, biotechnology, and quality assurance, are presented. U.S. laws and regulations that are related to drug product development, including clinical trials, manufacture, and distribution, are discussed. Vol. 18, pp. 480–510, 39 refs. to August 1995.
Phenolic Resins
Authors: Kopf Peter W.
Published: July 2004

Phenolic resins are a family of polymers and oligomers composed of a wide range of structures based on the various reaction products of phenols with formaldehyde. Applications vary from commodity construction materials to high technology applications in electronics and aerospace. Phenolic resins are prepared using acidic or basic catalysts. Weak Lewis acids, such as zinc acetate, are used for specialty resins. Phenolic novolaks are thermoplastic resins prepared from acid catalysts and a molar excess of phenol. They have a molecular weight of 500–5000 and a glass‐transition temperatureTgof 45–70°C. Novolak resins are typically cured with 5–15% hexamethylenetetramine as the cross‐linking agent. Resole‐type phenolic resins are produced with a molar ratio of formaldehyde to phenol of 1.2:1 to 3.0:1 and alkaline catalysts such as NaOH, Ca(OH)2, and Ba(OH)2. A typical resin has an initial molecular weight of 150 to perhaps 1500. For systems of unsubstituted phenols, the final cross‐link density is 150–300 atomic mass units per cross‐link. In 2001, worldwide consumption of phenolic resins exceeded 4 × 106t; slightly less than half of the total volume was produced in the United States, where the largest volume application is in plywood adhesives and accounts for ca 49% of U.S. consumption. As a mature industry, U.S. production of phenolic resins has paralleled the growth in the GNP. Applications for phenolic resins include coatings, adhesives, carbonless copy paper, molding compounds, bonded and coated abrasives, friction materials, foundry resins, laminates, air and oil filters, wood bonding, fiber bonding, composites, spherical fillers, and fibers. Factors contributing to the health and safety concerns of phenolic resins are related primarily to the presence of unreacted phenol and formaldehyde. Unreacted phenol in a resin can range from >10% for liquid resoles used in impregnation processes to <1% for novolaks intended for use as epoxy hardeners. Free formaldehyde can be 2–4% in liquid adhesives.
Amines, Aromatic, Phenylenediamines
Authors: Layer Robert W.
Published: July 2004

Phenylenediamines are aromatic amines with two amino groups attached to benzene. They are called benzenediamines byChemical Abstracts.There are three phenylenediamines; ortho, meta, and para; or 1,2‐; 1,3‐; and 1,4‐benzenediamines, respectively. Since they are difunctional, they are easily converted to polymers. Them‐phenylenediamines are the least expensive isomers and are used in the largest volumes for the manufacture of polyurethanes.p‐Phenylenediamine is used for the manufacture of polyamides with exceptional tensile strength. The unique chemistry of thep‐phenylenediamine derivatives makes them useful in the photographic and dye industries, and widely used as antioxidants and antiozonants for rubbers and plastics. The three phenylenediamines are all white solids when pure, but darken after standing in air. They are all very soluble in hot water. The phenylenediamines are aromatic amines which undergo typical amine reactions, such asN‐acylation andN‐alkylation. Commercially the largest‐volume usage of phenylenediamines is in the manufacture of diisocyanates; large volumes ofN,N′‐alkyl/aryl‐p‐phenylenediamines are also manufactured. Them‐phenylenediamines are easily obtained by dinitrating, followed by catalytically hydrogenating, an aromatic hydrocarbon. Like aniline, phenylenediamines may be toxic. Appropriate substitution ofp‐phenylenediamine, generally on the nitrogen with phenyl or larger alkyl groups, significantly reduces its toxicity.
Phenol
Authors: Wallace Jim
Published: July 2004

Phenol (hydroxybenzene) is a commercially important derivative of benzene. It is the primary feedstock for the production of epoxy resins and polycarbonates, phenolic resins and molding compounds, caprolctam, aniline, and other chemical derivatives.

More than 95% of the 4,691,000 m/yr consumed is produced by the cumene peroxidation process. Phenol is a white, crystalline mass at room temperature. Its freezing point is 40.91°C. It is a protoplasmic poison that is corrosive to living tissue and is readily absorbed through the skin.

Phenol's consumption growth rate of 3% is based primarily on its use in engineering plastics such as polycarbonates, polyetherimide and poly(phenylene oxide), and epoxy resins for the electronics industry. Due to the nature of its end markets, phenol consumption is highly cyclic. Future production processes for phenol will be affected by the disparity in growth rate between phenol and its coproduct, acetone.
Phosphorus
Authors: Brummer J. R. , Keely J. A. , Munday T. F.
Published: July 2004

The manufacture of elemental phosphorus by the electric furnace route, a mature and worldwide process, is reviewed. The principal product is white phosphorus although some red phosphorus is made from the white for specialty uses. Reduction in phosphorus production capacity has resulted from the detergent phosphate bans in the Western Hemisphere, the construction of wet‐acid purification plants, and increased electric power costs. Additional capacity is being built in China.

Most phosphorus is converted into phosphoric acid or phosphates and is used for cleaning compounds, food and beverages, water and metal treatment, and electronics. The remainder is converted into other derivatives and is used for flame retardants, agricultural chemicals, lubricants, and plasticizers. By‐products of phosphorus manufacture are slag, ferrophos, precipitator dust, and carbon monoxide off‐gas.
Phosphoric Acids and Phosphates
Authors: Gard David R.
Published: July 2004

Most commercial applications of phosphorus‐containing materials are based on phosphoric acids and the phosphates. Uses, other than as fertilizer, include applications in detergency, foods and food processing, dental materials, dentifrices, metal surface treatments, flame retardency, etc. Structures and properties of orthophosphoric acid and condensed phosphoric acids are presented. The manufacture of technical‐ and food‐grade phosphoric acids by thermal and wet acid purification processes, as well as some of the uses of the various phosphoric acids, are discussed.

The chemistry and properties of orthophosphates and condensed phosphates are presented. Emphasis is placed on alkali metal and calcium salts and their solution properties. Properties specific to condensed phosphate salts such as hydrolysis and metal ion complexation are outlined. Manufacturing schemes for the phosphates are described and attention is given to the control of product properties.
Fluorine Compounds, Inorganic, Phosphorus
Authors: Lindahl Charles B. , Mahmood Tariq
Published: July 2004

Phosphorus forms many fluorine compounds, including the binary fluorides, oxyfluorides, thiofluoride, and the various fluorophosphoric acids and their salts. Whereas PF5behaves as a Lewis acid, phosphorus trifluoride behaves as a Lewis base. PF5is used as a catalyst in the electronics industry and in ion implantation for semiconductors. The mono‐, di‐, and hexafluorophosphoric acids are commercially available. Hexafluorophosphoric acid is used in polymerization and preparation of its salts, a number of which exist. Particularly important commercially are sodium monofluorophosphate and potassium hexafluorophosphate, used as a dentifrice additive and as a catalyst for polymerization processes, respectively. The highly toxic fluorophosphate esters have found use in medical applications as well as in warfare. The polymerized esters are also known.
Phosphors
Authors: Srivastava Alok M. , Soules Thomas F.
Published: July 2004

Luminescent Materials (Phosphors). Commercial phosphors are typically inorganic powders which convert some form of invisible exciting energy into visible light. For this reason and because they can be quite efficient energy converters, they are commonly used in lamps, television screens, display terminals, x‐ray machines, and a variety of other applications. All of these types of phosphors are discussed in some detail. What phosphors consist of, how they work, how they are made, and some of the technological aspects of their production and use in each application are described. There are a wide variety of materials which luminesce under some form of excitation including common minerals and many organic dyes. However probably less than a hundred of these materials are efficient enough and maintain their efficiency well enough in the environment of their application to have any technological significance. All of these materials are inorganic compounds although there are many more organic compounds which fluoresce. The article is intended to be comprehensive but does not include specialized knowledge about certain phosphor materials or information on new or experimental phosphors or phosphor applications which are not widespread, eg, infrared‐to‐visible converting phosphors which although very interesting are used only in certain laser applications.
Chromogenic Materials, Photochromic
Authors: Samat A. , Guglielmetti R.
Published: July 2004

Photochromism has been defined as a reversible change in the color, or darkening of a material caused by absorption more generally of ultraviolet or visible light. The change in color is due to a modification of the compound structure and implies a change in the absorption spectrum in the visible range (400–750 nm). The reversion of the system to its original state can be driven either by thermal or photochemical energy (photobleaching), or both, depending on the chemical systems. Photochromic systems are naturally divided into two broad categories : inorganic and organic.

Within the inorganic category, the most well‐studied and commercially used systems are those containing silver halide crystallites dispersed throughout a glass matrix. The mechanism of the silver halide photochromism is the reversible formation of silver metal. Both the photochemical formation of silver and the thermal reformation of silver halide are catalyzed by copper ions. The silver halide glass systems have been used commercially in photochromic eyewear.

Since 1990, the organic photochromic systems have been a dramatic development in the area of variable optical transmission materials and especially for ophthalmic applications. Indeed polymer glasses have also been greatly developed and are compatible with organic pigments. The most common families are those involving electrocyclic reactions and within this class thermoreversible indolinospirooxazines and naphthopyrans have received the most attention.

Indolinospirooxazines were the first photochromic compound used in the preparation of commercially acceptable organic photochromic ophthalmic lenses.

Moreover, the area of optical memories and switches has been also a prodigious development and the families of photoreversible fulgides and diaryl (or heteroaryl) ethenes have been extensively studied and used for this type of applications.

Finally, many potential applications are possible with photochromic pigments using not only the change of color, but the modifications of physico‐chemical properties under the effect of light irradiation.