bluuebunny/crossref_metadata_2025 huggingface dataset:
Liquid Crystalline Materials
Authors: Collings Peter J.
Published: July 2004

Liquid crystals are a state of matter in which the molecules diffuse randomly as in liquids but retain some orientational order as is typical of solids. Many thousands of organic compounds, including rigid‐rod polymers and other macromolecules, exhibit liquid crystallinity, either in their pure form or when mixed with a liquid solvent. Liquid crystalline materials are studied both for the basic scientific understanding of this phase of matter and for the possibility of practical applications. To date, the most important application is the low power consuming liquid crystal display (LCD). Topics covered in the article include orientational and positional order in fluids, thermotropic liquid crystals, lyotropic liquid crystals, polymorphism, synthesis, polymer liquid crystals, liquid crystals in biological systems, and applications.
Fuels, Synthetic, Liquid Fuels
Authors: Han Scott , Chang Clarence D.
Published: July 2004

The creation of liquids to be used as fuels from sources other than natural crude petroleum broadly defines synthetic liquid fuels. Synthetic liquid fuels have characteristics approaching those of the liquid fuels in commerce, specifically gasoline, kerosene, jet fuel, and fuel oil. For much of the twentieth century, the synthetic fuels emphasis was on liquid products derived from coal upgrading or by extraction or hydrogenation of organic matter in coke liquids, coal tars, tar sands, or bitumen deposits. However, much of the direction involving synthetic fuels technology has changed.

The potential of natural gas, which typically has 85–95% methane, has been recognized as a plentiful and clean alternative feedstock to crude oil.

The proven technology to upgrade methane is via steam reforming to produce synthesis gas, CO + H2. Such a gas mixture is clean and when converted to liquids produces fuels substantially free of heteroatoms such as sulfur and nitrogen. Two commercial units utilizing the synthesis gas from natural gas technology in combination with novel downstream conversion processes have been commercialized.

The direct methane conversion technology has received the most research attention and involves the oxidative coupling of methane to produce higher hydrocarbons such as ethylene.

A second trend in synthetic fuels is increased attention to oxygenates as alternative fuels as a result of the growing environmental concern about burning fossil‐based fuels. The environmental impact of the oxygenates is still under debate, but these alternative liquid fuels are gaining new prominence.

Despite reduced prominence, coal technology is well positioned to provide synthetic fuels for the future. World petroleum and natural gas production are expected ultimately to level off and then decline. Coal gasification to synthesis gas is utilized to synthesize liquid fuels in much the same manner as natural gas steam reforming technology. Although world activity in coal liquefaction technology is minimal, the extensive development and detailed demonstration of processes for converting coal to liquid fuels should serve as solid foundation for the synthetic fuel needs of the future.

Coal, tar, and heavy oil fuel reserves are widely distributed.

The importance of coal gasification as a means of producing fuel gas(es) for industrial use cannot be underplayed. But coal gasification systems also have undesirable features. A range of undesirable products are also produced which must be removed before the products are used to provide fuel and/or to generate electric power. Natural gas is a plentiful resource, and there has been a marked tendency not to use other fossil fuels as SNG sources. However, petroleum oil shale, and biomass have been the subject of extensive research efforts.
Liquefied Petroleum Gas
Authors: Taylor R. Ray
Published: July 2004

Liquefied petroleum gas (LPG) is a subcategory of a versatile class of petroleum products known as natural gas liquids that are produced with and extracted from natural gas. Other natural gas liquids include natural gasoline and ethane. LPG is also produced from the refining of crude oil. It is commercially available as propane, butane, and butane–propane mixtures. Specifications of the commercial LPG products depend on composition and vary between wide limits.

The manufacture and processing of LPG is partially dependent on the desired by‐product as well as the process economics. Purification procedures involve both amine and caustic treatments to remove sulfur as well as dehydration and fractionation. Shipment and storage require specialized equipment.

Principal uses of LPG include as a fuel and as a petrochemical feedstock.
Extraction, Liquid‐Solid
Authors: Wakeman Richard J.
Published: July 2004

Liquid‐solid extraction is complex at the fundamental level, which is masked by the apparent simplicity of industrial processes used to effect extraction. The structure of solids which have to be extracted is varied, and leads to a combination of diffusional and other mass‐transfer processes which effect solvent contact and solute extraction. Other factors that determine extraction rates and hence equipment size include particle size, physical and chemical properties of the solvent, solubility dependences on temperature, and solvent agitation. Extractors rely on either percolation or agitation to give intimate contact between the solvent and the solids to be extracted. Early batch extractors have to some extent been superseded by continuous devices where the mode of solids transport offers the key to successful operation. The method of solids transport is used as a means of classifying the different equipment types. The design of an extraction system generally requires that careful consideration be given to safety and environmental factors, particularly with regard to solvent and dust loadings in the atmosphere of the working environment.
Lithographic Resists
Authors: Hinsberg W. D. , Wallraff G. M. , Allen R. D.
Published: July 2004

An introduction to the chemistry and applications of lithographic resists is presented. The historical development of these materials is reviewed, the characteristics of resists with current technological importance are described, and a view of anticipated future developments in the field is offered.
Fluorine Compounds, Inorganic, Lithium
Authors: Papcun John R.
Published: July 2004

Lithium fluoride is used primarily in the ceramic industry to reduce firing temperatures and improve resistance to thermal shock, abrasion, and acid attack. It is also used in flux compositions with other fluorides, chlorides, and borates for metal joining, and is an essential component of the fluorine cell electrolyte. Properties are described.
L‐Monosodium Glutamate(MSG)
Authors: Kawakita Tetsuya
Published: July 2004

Monosodium glutamate (MSG), more specifically monosodiumL‐glutamate, is used in large quantities as a flavor enhancer throughout the world. The world capacity for production of MSG continues to increase. Demand is expected to increase in developing countries as its use in commercially prepared packaged foods, ready‐made soups, and as a table seasoning increase MonosodiumL‐glutamate,\documentclass{article}\usepackage{amssymb}\pagestyle{empty}\begin{document}${{\rm{C}}{_{5}}{\rm{H}} _{8}{\rm{NO}}{_{4}}{\rm{Na}}{\cdot{}}{\rm{H}}{_{2}}{\rm{O}}}$\end{document}, crystallizes from aqueous solution at room temperature as rhombic prisms. Commercially preferred crystals for use as flavor enhancement are obtained by crystallization in the presence of amino acids such as alanine. Glutamic acid‐producing microorganisms are distributed widely throughout the natural environment. They are classified taxonomically as theMicrococcus, Brevibacterium, Corynebacterium,andAerobactersp. andMicrobacteriumgenera. Most of these microorganisms are gram‐positive, nonspore‐forming, nonmotile, and require biotin for growth. The carbon sources for biosynthesis of glutamic acid include acetic acid and the commonly used carbohydrates. For industrial production, molasses and starch hydrolyzate are generally used at present. MonosodiumL‐glutamate elicits a unique taste, known as umami, which is different from the four basic tastes of sweet, salty, sour, and bitter.L‐Glutamic acid is employed as a pharmaceutical and raw material for cosmetics. The acute toxicity of MSG is low. The main use of MSG is as a food ingredient. No specific toxic effects, and no evidence for carcinogenicity or mutagenicity have been demonstrated.
Polyethylene, Low Density
Authors: Pebsworth Lloyd W.
Published: July 2004

The article presents a review of the properties, manufacture, reaction kinetics, and applications of low density polyethylene (LDPE), covering general properties relating to crystallinity and molecular weight, as well as specific properties such as density, melt viscosity, tensile and impact strength, stress crack or chemical resistance, electrical properties, and film appearance. It also examines emission reduction and energy conservation during manufacture, reaction kinetics concerning control of chain length, short‐ and long‐chain branching, and lists common comonomers, chain‐transfer agents, and reaction initiators. Finally, the article details end use consumption by application, with particular emphasis on the blown film and extrusion coating areas, and summarizes various environmental issues.
Lubrication and Lubricants
Authors: Booser E. R.
Published: July 2004

This article outlines the fundamental principles involved in friction, wear, and lubrication. Refining, compounding practices, and trends are described for petroleum lubricants, which supply 98% of automotive and industrial needs, and the production of chemical additives is also covered. Composition and functioning of these additives are described for enhancing oxidation stability, corrosion resistance, wear reduction, viscosity–temperature characteristics, and other performance characteristics for specific applications. Chemical compositions and unique properties are discussed for the production of synthetic lubricants which is rapidly growing to fill needs of the military, automotive engines, and industry for broader temperature range, longer life, fire resistance, and better matching of machinery and environment. Subsequent coverage follows for greases, solid‐film lubricants, metalworking lubrication, radiation stability, and extreme temperature lubrication with gases, liquid metals, and glass. Production trends, recycling practices, and toxicity factors are given.
Magnetic Spin Resonance
Authors: Kiemle David J. , Winter William T.
Published: July 2004

Magnetic spin resonance techniques are among the most powerful methods available for determining primary structure, conformation, and local dynamic properties of molecules in liquid, solid, and even gas phases. Both organic and inorganic species can be studied.

An overview of nuclear magnetic and electron spin resonance spectroscopy theory, equipment, and practice is presented. Theory is briefly reviewed, giving particular attention to the differences between the two techniques. The basic modules comprising a magnetic resonance spectrometer, function, and limitations are discussed. One‐dimensional and multidimensional experiments for both the most common nmr nuclei,
1
H and
13
C as well as several less commonly studied species, are described. Applications of nmr studies to larger molecules such as proteins, nucleic acids, and other polymers both in solution and in the solid state are mentioned, and a brief description of EPR experiments is included. References are given for all areas. This article is current through summer 1994 except for the use of gradient field spectroscopy.
Separation, Magnetic Separation
Authors: Morgan Don
Published: July 2004

Morgan, Don (O. S. Walker Co.). The application of magnetic separation relies on the behavior of individual particles under the influence of a magnetic field. Several types of magnetic devices are used, ranging from those for the removal of highly magnetic materials to those for feebly magnetic materials and minerals. Magnetic units may be used as head pulleys of conveyors, magnets suspended over conveyors, magnetic drums, plate and grate magnets, or eddy current separators. These last are employed in recycling operations and other metal operation systems. Conventional magnets are discussed and standard available sizes and the operational value in systems where they are installed are provided.

Magnetic separators that are used in wet processes for the recovery of magnetite from heavy‐media separation plants, as well as iron ore recovery, are also discussed. Wet high intensity magnetic separation is introduced. Recommended capacities, feed rates, and magnetic sizes are given.
Magnesium and Magnesium Alloys
Authors: Kramer Deborah A.
Published: July 2004

Magnesium is the world's most readily available metal and occurs naturally in minerals, brines, and seawater. Magnesium metal is prepared commercially by two types of processes. In the first process, magnesium chloride is recovered from the raw materials and converted to metal by molten salt electrolysis. The second process involves the reduction of magnesium oxide with silicon or aluminum at high temperatures. The resulting metal is then cast into a variety of shapes and sizes of ingots, or alloyed with various other metals and made into ingots, slabs, billets, and many extruded shapes. Pure magnesium is used for making aluminum alloys, the desulfurization of steel, the manufacture of ductile iron, and as a reducing agent for the production of other metals. Elemental magnesium is the lightest structural metal. Magnesium alloys are used mainly in die and sand castings, and in the manufacture of wrought products. Alloy composition is varied to obtain the desired physical and mechanical properties for a given application. Production capacities, import and export data are given. Magnesium is essential to most plant and animal life.
Maintenance
Authors: Bergtraun Eric M.
Published: July 2004

One of the goals of good management is to operate with a predictive and preventive maintenance program that prevents unscheduled utility service interruptions and machine breakdowns. A reasonable cost of such a program contributes to the profitability of manufacturing plants and results in reduction of operating costs and increased productivity. This all can be accomplished by organizing, managing, and controlling maintenance.

A good maintenance program should include designing, laying out, and constructing facilities with maintenance in mind; providing for reliable utilities and their uses; developing a maintenance organization and program while the facility is under construction; developing a simple, practical, predictive, and preventative maintenance program; supplementing an in‐house maintenance organization with contract maintenance; motivating the maintenance workers; organizing safety as an important function of any maintenance program; including environmental care and appreciation in any maintenance program; developing an energy conservation program as part of the maintenance program; creating a partnership with suppliers and equipment manufacturers; cooperating with other service groups of the facility; and controlling costs and assuring budget responsibility.
Market and Marketing Research
Authors: Tarnell Edward
Published: July 2004

Market research is a technique used to secure data for management to use in decision making. Marketing research is concerned with identifying existing or potential users of a product. The paper discusses and describes both types of research, and includes discussions of market and marketing research organizations, purchasing research, and competitive intelligence.
Mass Spectrometry
Authors: Moore Colin
Published: July 2004

Mass spectrometry is a technique which involves measurements of mass‐to‐charge ratios of the ions formed when a sample is ionized. The types of spectrometers available commercially are listed, as are the ionization techniques and types of mass spectrometers used to solve analytical problems in biotechnology, environmental studies, oil analysis, polymer chemistry, and inorganic applications. Detailed descriptions of instrumental components, the various ion paths, and data analyses are presented. Mass spectrometers for tandem mass spectrometry are discussed. The methodologies used to interface hplc and other separations systems to mass spectrometers are described. Techniques utilizing ionization techniques such as secondary ions, glow discharges, and inductively coupled plasma are used for many analyses.
Matches
Authors: Bean Mark C.
Published: July 2004

The development of the ordinary match followed thousands of years of fire‐making by laborious means. It has been perfected in the twentieth century and its formulations have remained basically unchanged. This article discusses the history of matches, mechanism of fire production, manufacture of matches, safety, and economics. The use of matches has declined considerably with the reduction of tobacco consumption and the growth of lighters as ignition sources, but match books remain an important means of advertising.
Materials Standards and Specifications
Authors: Westbrook Jack H.
Published: July 2004

Westbrook, Jack (Brookline Technologies). A comprehensive overview of materials standards and specifications is presented. Discussion of standards includes types, the generation process, administration, implementation, standard reference materials, standard reference data, nondestructive evaluation standards, traceability, and a detailed review of basic standards for chemical technology. Comparable treatment of specifications includes objectives and types, content, use strategy and implementation, economic, legal, and educational aspects, and discussion of trends in the field. International standards and specifications, computerization, and the need to consider the use of standards and specifications in various hostile environments are all considerations. A reference section compiling standardization journals, sources of standards and specifications domestic and worldwide, and directories and cross‐reference aids is included.
Meat Products
Authors: Schmidt Glenn R. , Raharjo S.
Published: July 2004

Consumers not only prefer good tasting meat products, but they also are concerned with the nutrition, safety, and wholesomeness of the meat products they consume. Consumers have been told that red meat is a significant source of saturated fat and consequently the consumption of meat has shifted from red meat to poultry. In response to consumer demand, meat processors are marketing various types of low fat meat products. These low fat meat products can be produced by using leaner meat cuts or adding or substituting ingredients for moisture retention or mimicking the sensorial properties of animal fat. To ensure the safety of the processed meat products, the industry and government regulatory agencies are adopting the hazard analysis critical control point (HACCP) system. The importance of the HACCP system is more obvious since consumers are demanding more convenient precooked products such as microwavable meat entrees or sous‐vide processed meat products which are not shelf stable. Descriptive terms on nutrition labels that convey information about the nutritional value or quality of a meat product are useful to consumers when making product choices.
Medical Imaging Technology
Authors: Hornak Joseph P.
Published: July 2004

Medical imaging is the component of the emerging discipline called imaging science and is concerned with the application of nonsurgical techniques to produce images of the organs and tissues inside the human body. The many technologies applied to produce medical images take advantage of the basic imaging principles of absorption, emission, and reflection of energy by tissues. The principal medical imaging modalities include endoscopy, x‐ray imaging, magnetic resonance imaging, ultrasound imaging, and nuclear imaging. These technologies have extended the frontiers of medicine into areas such as mapping brain function. Technological advances in computers, electronics, and magnetics have aided in the development of medical imaging. The theory and specialized equipment of each technique is presented. Application and safety issues are addressed.
Memory‐Enhancing Drugs
Authors: Zaczek Robert , Chorvat Robert J.
Published: July 2004

Whereas memory enhancement can be viewed as generally beneficial to many individuals, agents being developed are almost exclusively for some form of impairment. The memory‐enhancing drugs therapeutically available offer only symptomatic relief rather than slowing or stopping the progression of dementia. The greatest effort in development has been in the areas of cerebral metabolism and neurotransmission enhancers. Cerebral vasodilators and nootropics have both been developed for usage, as have cholinergic enhancers.
Mercury
Authors: DeVito Stephen C.
Published: July 2004

DeVito, Stephen C. (U.S. Environmental Protection Agency). Mercury, used for centuries in many industrial and consumer applications and products because of the unique physical and chemical properties of the metal, is defined as being a hazardous material. The toxic effects of the metal to workers and to the general population as a result of occupational exposure, consumer exposure, and environmental pollution have gained worldwide attention in the last part of the twentieth century. Much effort has been devoted to limiting the production and use of mercury, and finding alternative technologies that are designed to supplant the need for mercury. Overall demand for mercury has decreased throughout the industrialized world and it is likely to continue to decline. The chemistry, properties, natural occurrence, production, processing, economic aspects, environmental releases, uses, and toxicity of mercury are reviewed. Regulatory restrictions imposed by the U.S. Environmental Protection Agency on the production, use, and disposal of the metal are also provided. Vol. 16, pp. 212–228, 45 refs. to June 1993.
Metal‐Matrix Composites
Authors: Chawla Krishan K. , Chawla N.
Published: July 2004

Metal‐matrix composites have a metal or an alloy as the continuous phase, in which the reinforcing phase (particle whisker, short or continuous fiber) is distributed. Important techniques for processing metal‐matrix composites are described. Description of the reinforcement/matrix interface region and its characteristics, and properties of different metal‐matrix composites are provided. Different applications of metal‐matrix composites are summarized.
Methacrylic Acid and Derivatives
Authors: Wilczynski Robert , Jerrick Juliette Jamie
Published: July 2004

Methacrylic acid (MAA) and its derivatives exhibit a rich array of chemistries and have found wide use in commercial applications, especially as monomers for making various types of polymer products. The predominant manufacturing route to the two simplest methacrylates continues to be via the conversion of acetonecyanohydrin (ACH) in sulfuric acid to methacrylamide followed by either hydrolysis to MAA or esterification with methanol to give methyl methacrylate (MMA). Alternative routes have reached or are now approaching commercialization. These include processes based on either ethylene (C‐2), propylene (C‐3), methylacetylene (C‐3), or isobutylene (C‐4) feedstocks, as well as a separate ACH process which does not involve sulfuric acid. The later route, which starts with catalyzed hydration of ACH to hydroxyisobutyramide followed by esterification and dehydration steps to MMA, has an added benefit of recycling HCN as a raw material. The ethylene‐based routes typically involve formaldehyde condensation on either a propionaldehyde or propionic acid intermediate. The isobutylene‐based routes involve oxidation processes to reach the methacrylate backbone, often passing through methacrolein as an intermediate. The propylene‐based routes typically involve isobutyric acid or isobutyraldehyde intermediates. The methylacetylene‐based process appears to be the most selective overall, where a single reaction with carbon monoxide and methanol leads directly to MMA. All of the synthetic routes require various types of catalysts to promote the separate steps involved. In addition to providing more details on each of these processes, the following article also provides information on volumes, costs, health and safety for methacrylic acid and its derivatives.
Methylene Chloride
Authors: Holbrook Michael T.
Published: July 2004

Methylene chloride is a colorless, heavy liquid with a pleasant ethereal odor. Its outstanding solvent properties are the basis of its principal industrial interest. It is produced almost exclusively by the chlorination of lesser chlorinated methanes along with coproducts chloroform and carbon tetrachloride. U.S. capacity has been estimated at 242,600 t/yr although there is considerable flexibility to change the mix of the coproducts made. Methylene chloride production has declined significantly since 1985 because of an unfavorable carcinogenicity test. A projected growth rate of 0% per year is expected. Its primary uses are for paint stripping and metal cleaning. It is regulated by many federal and state laws.
Amines, Aromatic, Methylenedianiline
Authors: Lowenkron Steven
Published: July 2004

Commercial production of 4,4′‐methylenedianiline (4,4′‐MDA) is carried out by the acid‐catalyzed reaction of formaldehyde with aniline. All processes produce polymeric MDA (PMDA), which consists of mixtures of isomers and oligomers of MDA. More than 99% of the manufactured PMDA products are used in reactions with phosgene to produce the corresponding isocyanates for use in polyurethanes. The resultant polymeric isocyanates (PMDI) are either sold commercially or are purified to isolate 4‐4′‐methylenediphenyldiisocyanate (MDI). MDI is an important intermediate in the manufacture of spandex fibers, thermoplastic resins, and coatings, and it is used in reaction injection molding (RIM) for automotive applications. The primary use of PMDI products is in rigid foam insulation, but they are also used in semiflexible foams, foundry core binders, and particle board manufacture. Nonisocyanate uses for MDA or PMDA include epoxy curing agents, filament wound pipe, wire coatings, and military applications. MDA reacts similarly to other aromatic amines under the proper conditions. All of the toxicity data on MDA have been collected using either 4,4′‐MDA or the corresponding hydrochloride salt. Because MDA is a potentially hazardous chemical, worker exposure should be kept to a minimum. The major exposure route in workers who experience MDA poisoning is by skin contact. MDA is a suspected human carcinogen.
Microscopy
Authors: Weaver Rob
Published: July 2004

The microscope is arguably the most indispensable and widely used scientific instrument. There are few science or engineering disciplines that do not utilize microscopes or the data they provide to understand processes and material's properties as well as test and develop new theories. Industrial applications of the microscope continue to grow as the scale of electronic devices has passed from the micrometer to nanometer level. Microscopes are used routinely in such diverse fields as forensic science, analytical chemistry, microbiology, pathology, materials science, mineral exploration, and environmental science. It is the intent of this article to provide a concise summary of the various forms of microscopy. A great amount of discussion is devoted to the three most common types of microscopes: light microscopes; electron microscopes; and scanned probe microscopes; however, other forms of microscopy such as X‐ray, acoustic and atom probe microscopes are also discussed. For each form of microscopy there is a discussion of the principles of image formation, areas of application and strengths and weaknesses.
Genetic Engineering, Microbes
Authors: Nagarajan Vasantha , Bramucci Michael
Published: July 2004

The techniques involved in isolation and manipulation of genes from several microbes have become routine. Genes are cloned into plasmid or phage‐based vectors and introduced into the microbe of choice. The number of vectors that have been engineered is on the increase for several systems. In addition, construction of gene libraries and screening are also performed by small biotechnology companies. Various computational tools have become essential. The number of nucleotide and protein databases is rapidly increasing. Many software packages are available to access, manipulate, and analyze sequences. Most of the reagents needed for gene manipulation such as oligonucleotides, peptides, vectors, and antibodies are commercially available. Genetically engineered microbes are used to produce several commercial products. The number of products is likely to increase. They include therapeutics, bulk enzymes, antibiotics, chemicals, and polymer products.
Microbial Transformations
Authors: Sebek Oldrich K. , Rosazza John P. N.
Published: July 2004

The technology of microbial transformations is concerned with harnessing the enzymes of microorganisms to catalyze useful reactions of organic compounds. Microbial enzymes are well known for their abilities to hydrolyze, oxidize, reduce, and otherwise change the structures of organic chemicals. This review summarizes important historical applications of microbes to transform steroids, amino acids, antibiotics, sugars, and others structural classes of compounds and introduces applications of microorganisms and their enzymes as reagents in synthetic organic chemistry. It covers reactions including oxidations (hydroxylation, dioxygenation, dehydrogenation, β‐oxidation, and Baeyer‐Villiger oxidation), reductions (of ketones, double bonds, and carboxylic acids), hydrolyses (esters, amides, and nitriles), condensations (acyloin, aldolase, and carboxylation), amination and deamination, dehydration,N‐ andO‐dealkylation, decarboxylation, conjugations (N‐acetylation,O‐phosphorylation, andO‐adenylylation) and isomerization. The methodology of microbial transformations is also described. Vol. 16, pp. 611–627, 100 refs. to September 1993.
Microemulsions
Authors: Smith Duane H.
Published: July 2004

Microemulsions are true, thermodynamically equilibrated solutions that contain a surfactant and/or other amphiphile(s); one or more nonpolar components, such as hydrocarbons; water; and, frequently, inorganic salt(s). The surfactant(s) may be nonionic, ionic, or amphoteric; but most ionic surfactants also require a nonionic cosurfactant or amphiphile to suppress formation of liquid crystals. Microemulsions are distinct from (macro)emulsions, which are thermodynamically unstable dispersions of macroscopic droplets of one or more liquid and/or liquid crystalline phases in a continuous liquid. However, a microemulsion may be one of the phases of an emulsion. The microemulsion may appear as one of three phases, for example, a middle phase in simultaneous equilibrium with a top or upper oleic phase, and a bottom or lower aqueous phase. Because the three phases are close to a tricritical point (where all three phases simultaneously become a single phase), the interfacial tensions among the three phases are several orders of magnitude less than the tensions produced by conventional micellar solutions. Moreover, by suitable changes of temperature, salinity, or other compositional variable, the composition of the middle phase can be made to vary continuously between that of the bottom and top phases. Current or potential industrial uses of microemulsions include agrochemicals, biotechnology, catalysis, cosmetics, detergency, dyeing, enhanced oil recovery, foods, pharmaceuticals,
in situ
remediation of pollutants, separations, and synthesis of nanomaterials. Annual U.S. consumption of surfactants is about 3.4 billion kg.
Microencapsulation
Authors: Thies Curt
Published: July 2004

Thies, Curt (Washington University). This article discusses the concept of microencapsulation, many processes by which microcapsules are produced, and a number of microcapsule applications. Nomenclature and selected materials used to form microcapsules are summarized briefly. Encapsulation processes discussed include complex coacervation, polymer–polymer incompatibility, interfacial andin situpolymerization, solvent evaporation, extractive drying, submerged stationary nozzle and centrifugal nozzle, spray drying, fluidized bed, and rotational suspension separation. Microcapsule applications discussed include graphic arts such as carbonless copy paper, prolonged herbicides and insecticides, oral and injectable pharmaceuticals, live cell immobilization for biomedical and biotechnological applications, enhanced performance of food ingredients such as flavors and vitamins, and several general consumer uses such as cosmetics and adhesives.
Microwave Technology—Chemical Synthesis Applications
Authors: Varma Rajender S.
Published: July 2004

Microwave‐accelerated chemical syntheses in various solvents as well as under solvent‐free conditions have witnessed an explosive growth. This technology, which is still in its growth phase, has found widespread application predominantly exploiting the inexpensive unmodified household microwave (MW) ovens although the use of dedicated MW equipment has been rapidly gaining ground. Of special interest is the environmentally friendlier solventless approach that often involves exposure of neat reactants to MW irradiation or employs supported reagents on recyclable inorganic oxides or catalysts and has been adequately demonstrated in several MW‐assisted condensation, deprotection, rearrangement, cyclization, reduction, and oxidation reactions. The rapid one‐pot preparation of heterocyclic compounds fromin situgenerated reactive intermediates and the general application to multicomponent reactions, that are adaptable for building a library of compounds, have been accomplished using this MW technique. More recently, the strategy has been extended to combinatorial chemistry and the synthesis of a newer class of solvents, ionic liquids that are essentially molten salts with barely measurable vapor pressure. The salient features of these high yield protocols, namely, the selectivity, experimental ease of manipulation, and the enhanced reaction rates are discussed.
Molybdenum and Molybdenum Alloys
Authors: Stiefel Edward I.
Published: July 2004

Molybdenum, a key industrial element, is used both in its pure form as a refractory metal and as an alloying element in irons and steels. Most molybdenum production is in North America, although some metal comes from other areas, especially from South America and China. The largest source of molybdenum is copper mines, where the former metal is a by‐product. Molybdenum supply, ore‐processing to commercial products, and the associated environmental considerations are reviewed.

Tools, pipelines, pumps, and various gears and dies, especially those for harsh working environments such as those found in the petroleum industry, are made from molybdenum containing alloys. The molybdenum imparts strength, hardness, and corrosion resistance to steels and cast irons. Molybdenum is a refractory metal used in furnaces, electrodes, light bulbs, and x‐ray tubes. Properties and uses are described.
Fluorine Compounds, Inorganic, Molybdenum
Authors: Meshri Dayal T.
Published: July 2004

The fluorides of molybdenum are described. Four binary molybdenum fluorides are known, but only molybdenum hexafluoride has commercial applications, principally in the electronics industry.
Water, Municipal Water Treatment
Authors: Singley J. E.
Published: July 2004

Most surface waters contain varying amounts of suspended solids, including silt, clay, bacteria, viruses, etc. It is necessary to remove these prior to distribution to domestic or industrial customers. Sedimentation and filtration are the principal treatment processes. These are discussed in detail. Also discussed is the removal of colloidal particles by coagulation and flocculation. Lime and lime‐soda processes, and ion exchange are used to control hardness of water. Data on taste and odor control methods, as well as removal of organic compounds, iron and manganese, which impact on water quality, are given.
Nanotechnology
Authors: Vaidya Rajesh , López Gabriel , López José A.
Published: July 2004

Molecular nanotechnology (also known as nanotechnology, molecular engineering, or molecular manufacturing) is the production of functional materials and structures in the 0.1 to 100 nm range (the nanoscale) by any of a variety of nanoscale physical and chemical methods. These methods include nanolithography, direct atomic and molecular manipulation with nanoscale probes, biotechnological selection and production of useful nanomaterials, and chemical synthesis and self‐assembly of functional molecules and aggregates. Examples of such materials and devices include molecular electronic devices (eg, molecular wires, diodes, transistors, memories), sensors, disease‐fighting agents (eg, microbicidal, anticancer), and assemblers (devices that manufacture a particular molecule or assembly of molecules) using nanoscale mechanical devices (eg, nanopumps, motors, gears). Nanoscale structures and devices may be constructed synthetically from their atomic or molecular constituents (the synthetic or “bottom‐up” approach, also referred to as nanochemistry), or may be constructed by fabrication techniques that use methods to form small structures from larger ones (the reductive or “top‐down” approach). Biological systems employ a variety of synthetic strategies and processes that make efficient use of a suite of atomic, interatomic, and intermolecular interactions to form highly ordered molecular and supramolecular units that perform myriad functions, including light harvesting, catalysis, environmental sensing, information storage and processing, locomotion, and self‐replication. Thus biological systems form important existence theorems and design criteria for the production of functional, nanoscale materials through nanotechnology. This article focuses on the current state‐of‐the‐art of methods that produce nanostructures and devices. These methods include biotechnology, nanolithography, atom manipulation by local probes, nanochemical synthesis, rational design, and supramolecular chemistry.
Naphthalene
Authors: Mason Robert T.
Published: July 2004

This article deals mainly with naphthalene. The hydrogenated naphthalenes, the alkylnaphthalenes (particularly methyl‐ and isopropylnaphthalenes), and acenaphthalene also are discussed. These aromatic hydrocarbons have the expected properties and undergo the usual reactions of electrophilic aromatic substitution as well as oxidation, a significant commercial reaction.Coal tar and petroleum are the sources of naphthalene in the United States. The principal use of naphthalene is for phthalic anhydride manufacture. Naphthalene is also a raw material for synthesis of pesticides, dispersants, and wetting agents.
Heat‐Exchange Technology, Network Synthesis
Authors: Hohmann Edward
Published: July 2004

Synthesis of heat‐exchange (energy) networks has shown large economic rewards and the most promise for future universal use.

The high cost of energy mandates carefully planned heat‐exchange networks for economically and environmentally viable plants. The process of developing a good heat‐exchange or energy network is most easily viewed as a multiple‐tier optimization problem. Minimum life‐time plant cost is the objective. The process includes minimizing capital and operating costs plus an emphasis on developing a robust design that includes the necessary flexibility and operability characteristics.

Many of the calculations necessary for heat‐exchange network design can be done by hand and need to be understood by every process engineer. Computational resources make it attractive for the average process designer to use a computer program to determine and evaluate alternative network configurations. Commercial heat‐exchange network programs are available and these programs typically take the raw stream data available to the process engineer for the plant and calculate the limiting network conditions. Heat‐exchange networks are concerned with just a portion of the total energy in a process plant. Ideally, a process plant should be examined for its total energy consumption.
Niacin, Nicotinamide, and Nicotinic Acid
Authors: Van Arnum Susan D.
Published: July 2004

The history of the discovery of nicotinic acid and nicotinamide is unusual in that these compounds were first synthesized and later their biological significance was elucidated. In the early part of the twentieth century, the importance of nicotinamide in the treatment of pellagra was determined. Specifically, nicotinic acid and nicotinic amide are constituents of the cofactors NAD and NADH which are required for many enzymatic reactions and the particular role of these cofactors is discussed. The key intermediate in the industrial synthesis of these compounds are alkyl pyridines. Methods of preparation of these intermediates as well as methods to functionalize the side chain are reviewed. Both biological and chemical approaches have found utility in this application. A review of analytical methodology is presented. An overview of the biological effects of these substances is presented. Despite their structural similarities, the safety and toxicity of these compounds are quite different and these consequences are highlighted.
Fluorine Compounds, Inorganic, Nickel
Authors: Meshri Dayal T.
Published: July 2004

Nickel(II) fluoride and its tetrahydrate are both available commercially. Uses vary from that of a catalyst to a component of ink. Nickel tetrafluoroborate plays an important role in the electroplating and electronics industries. Preparation and properties are described.
Nickel and Nickel Alloys
Authors: Tundermann John H. , Tien John K. , Howson Timothy E.
Published: July 2004

World nickel reserves and nickel production and consumption are reviewed. The types of nickel ores that can be economically mined and the extraction and refining processes used to obtain commercial nickel products are described, as are the forms, characteristics, and uses of these products. The physical constants for nickel and the nominal chemistries and properties of a range of cast and wrought nickel alloys and superalloys are listed. The development paths for wrought nickel alloys are given.

Alloying copper, chromium, iron, molybdenum, and other elements with nickel produces a range of corrosion‐ and heat‐resistant materials strengthened by various means. These alloys can operate from cryogenic conditions to temperatures

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{\rm{C}}}$\end{document}

. Nickel containing oxide‐dispersion‐strengthened alloys, nickel–aluminide intermetallics, and advanced nickel‐matrix composites are presented.
Nitrogen
Authors: Hardenburger Thomas L. , Ennis Matthew
Published: July 2004

Nitrogen is an important industrial gas and an element that is essential to all life. Most naturally occurring, noncombined nitrogen exists as a diatomic gas sometimes referred to as dinitrogen. Dinitrogen is an extremely stable, relatively inert molecule. High temperatures are generally required to coax its reactivity. Due to its inert nature, gaseous nitrogen finds wide application in many industrial processes as a blanketing and purging agent. Dinitrogen liquifies at

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to a colorless liquid. Liquid nitrogen is used in many applications as an inert, expendable refrigerant. All commercial nitrogen uses atmospheric air as the feedstock. The principal manufacturing processes include cryogenic distillation, pressure swing adsorption, membrane permeation, and combustion‐based processes. At the present time, cryogenic distillation is the most significant. Commercial nitrogen is distributed in very large volumes by pipeline or in smaller volumes in liquified form for use or vaporization at the use point or in compressed gaseous form in steel cylinders. Nitrogen is nontoxic but does not support life, therefore care is required before entering areas suspected of being nitrogen‐enriched.
Fluorine Compounds, Inorganic, Nitrogen
Authors: Henderson Philip B. , Woytek Andrew J.
Published: July 2004

Nitrogen has four binary fluorides: nitrogen trifluoride, tetrafluorohydrazine, difluorodiazine, and fluorine azide. There are numerous other nitrogen fluorine compounds, the most significant of which are the perfluoroammonium salts based on the NF
+
4
cation. Of all the nitrogen fluorine compounds, only NF
3
has been of commercial importance. Nitrogen trifluoride is used as an etchant gas in the electronic industry and as a fluorine source in high power chemical lasers.
Nitriles
Authors: Mckinney Ronald J. , DeVito Stephen C.
Published: July 2004

Nitriles are cyano‐substituted organic compounds, ie, organic derivatives of hydrogen cyanide. The combination of unique physical properties imparted by the nitrile group and the ease with which nitrile groups can be converted to other functional groups has made organonitrile compounds commercially important substances. Organonitriles may be prepared by a variety of methods including metathesis of organohalides, ammoxidation of hydrocarbons, dehydration of amides, and addition of hydrogen cyanide to unsaturated organic compounds such as aldehydes, ketones, and olefins. Some of the more common transformations include hydrolysis or alcoholysis to produce amides, acids and esters, and hydrogenation to produce amines, which are intermediates for the production of polyurethanes and polyamides. Nitriles are generally toxic to the extent that they may be metabolized in the body to liberate cyanide, and care in the body to liberate cyanide and care should be taken to prevent skin contact or inhalation of vapors. This article addresses the following organonitrile compounds in some detail: acetonitrile, adiponitrile, a‐aminonitriles, azobisnitriles, benzonitrile, cyanoacetic acid (and esters), isophthalonitrile, methylglutaronitrile, pentenenitriles, and fatty acid nitriles.
Nitrogen Fixation
Authors: Newton William E.
Published: July 2004

Nitrogen fixation converts inert atmospheric molecular nitrogen gas into reduced forms whereby the nitrogen may be used by all life forms for protein and nucleic acid production. The biological process occurs only in microorganisms and is the principal contributor of fixed nitrogen to the biosphere. Fixed nitrogen is also derived from nonbiological processes, such as fires, volcanoes, and lightning, and from industrial fixation. The Haber‐Bosch ammonia process is highly energy‐intensive but is the most economical industrial process available. Agriculturally, the most important source of biologically fixed nitrogen is the symbiotic system involving leguminous plants which harbor rhizobia bacteria in nodules on their roots. Smaller contributions are made by other, less formal systems and by free‐living microbes. All of the biological systems use a similar metalloenzyme complex, called nitrogenase. Nitrogen fixation research is discussed from a genetic standpoint, as well as in terms of model chemistry and economic advantages of the biological system. The chemical approaches aimed at duplicating the biological process are presented.