bluuebunny/crossref_metadata_2025_split huggingface dataset:
Photography
Authors: Locker David J. 
Published: July 2004

AbstractConventional silver halide‐based photography is discussed. The key subprocesses in the photographic industry are examined. The manufacture of photographic films and papers begins with the production of silver halide microcrystals which are grown via the controlled mixing of silver nitrate and alkali halides in an aqueous environment, a process generally referred to as emulsion precipitation. To increase the light sensitivity of the resulting microcrystals, two sensitization processes are employed: chemical sensitization and spectral sensitization. Chemical sensitization usually involves the addition of trace levels of gold‐ and sulfur‐containing compounds to the surface of the microcrystalline silver halide grains. These sensitizing chemicals increase the sensitivity of the crystals to photons absorbed during exposure. Because silver halides do not significantly absorb photons with wavelengths greater than 500 nanometers, spectral sensitizing dyes are adsorbed to the surfaces of the microcrystals. Dyes are selected to provided sensitivity to different wavelengths depending on the photographic application. After the sensitization process is complete, the silver halide crystals can be coated on film or paper bases. Gelatin is used as the supporting vehicle for the sensitized microcrystals. Exposure generates mobile conduction band electrons and valence band holes and ultimately yields small nuclei which contain only a few atoms of metallic silver. These silver nuclei are referred to as latent‐image centers and provide a site for subsequent catalytic amplification during development. High amplification gains during development, image sharpness, low granularity, and archival permanence of developed photographic images are some of the reasons why conventional photography holds a preeminent position in the image‐formation industry.
Photocatalysis
Authors: Serpone Nick 
Published: July 2004

AbstractWhen photons are implicated in a catalytic reaction, the system becomes a photocatalytic one. The catalyst may accelerate the photoreaction by interaction either with a substrate in its ground or an excited state, and/or with the primary photoproduct. Although not yet commercially viable, photocatalytic processes may provide an alternative to the traditional routes to water purification, destroying bacterial substances, and dissolved organics in waste streams. The process can be homogeneous, employing an oxidant and ultraviolet light, or heterogeneous, utilizing air, semiconductor particles (the photocatalyst), and ultraviolet radiation. These various pathways are discussed.The mechanistic details of using semiconductor particles as light harvesters is reviewed, as are the mechanisms by which the photooxidation occurs. Examples of aqueous dissolved organic compounds photooxidized to carbon dioxide and water in the presence of titanium dioxide, air, and near‐ultraviolet radiation are given.
Photoconductive Polymers
Authors: Wang Ying 
Published: July 2004

AbstractPhotoconductive polymers are insulators in the dark but become conductive when irradiated by light. They are widely used in the imaging industry as either photosensitive receptors or carrier transporting material in copy machines and laser printers (electrophotography). This is one of the few areas in electronics in which polymers are used on a large‐scale industrial basis and are clearly superior or equivalent to inorganic semiconductors.This article reviews material properties of a wide variety of photoconductive polymers. Important parameters such as carrier mobility and charge‐generation efficiency are tabulated. Mechanisms for charge generation and charge transport of polymers are discussed. Potential applications in areas other than electrophotography are also considered.
Phthalocyanine Compounds
Authors: Loebbert Gerd 
Published: July 2004

AbstractPhthalocyanines, a class of organic dyes, were discovered in 1907 and today are the main organic blue and green pigments in the industry. Phthalocyanines form complexes with a variety of chemical elements. The most important phthalocyanine, copper phthalocyanine, is produced worldwide. Synthesis usually starts with phthalodinitrile and metal or phthalic anhydride, urea, and metal salts as the starting materials. The reactions can be carried out in a solvent or at higher temperatures in a dry state. The chemical stability and physical properties have stimulated applications of phthalocyanines in fields like semiconductors, catalysts, lasers, and lubricants. However, 90% of the phthalocyanines are used as pigments for printing inks, paints, coatings, plastics, textile, and spin dyeing industries. Phthalocyanine dyes are predominantly used for dyeing of textiles, paper, and leather. The predominant phthalocyanine derivatives are formed with halogens (green pigments), sulfonic acids, and sulfonyl chlorides (dyes).
Phthalic Acids and Other Benzenepolycarboxylic Acids
Authors: Park Chang‐Man , Sheehan Richard J. 
Published: July 2004

AbstractThere are 11 benzenepolycarboxylic acids, some of which are sold as the anhydride or the methyl ester. Two of these substances, terephthalic acid and phthalic anhydride, are principal chemical products. Two others, isophthalic acid and trimellitic anhydride, have substantial commercial sales. The rest have low volume specialized applications or are not available commercially. This is a review of the basic physical properties, manufacturing methods, production volumes and prices, toxicological aspects, and uses of these compounds.Terephthalic acid and its dimethyl ester rank about tenth in tonnage for all organic chemicals, and production is expanding substantially. They are used to make poly(ethylene terephthalate) for fibers, film, and containers. The principle mode of commercial manufacture is direct liquid‐phase oxidation ofp‐xylene using a homogeneous heavy metal–bromine catalyst system. Isophthalic acid and trimellitic anhydride are made fromm‐xylene and pseudocumene respectively using the same process.Phthalic anhydride is made primarily by gas‐phase oxidation ofo‐xylene over a fixed catalyst containing vanadium and titanium oxides. It is used as a raw material for plasticizers, unsaturated polyesters, and other resins.
Chromogenic Materials, Piezochromic
Authors: Samat A. , Guglielmetti R. 
Published: July 2004

Abstract
In its most general sense the term, piezochromism, is defined as the change in color of a solid under compression.
There are three aspects of the phenomenon: The color of a solid results from the absorption of light in selected regions of the visible spectrum by promotion of an electron from the ground electronic state to a higher level. If the two electronic energy levels are perturbed differently by pressure, compression results in a color change. This is the basic definition of pressure tuning spectroscopy.
A discontinuous change of color occurs when a crystalline solid undergoes a first‐order phase transition from one crystal structure to another.
The phenomenon of most interest is change in color of a solid as a result of a change in the molecular geometry of the molecules that make up the solid.
The main piezochromism systems are organic molecules in crystals and polymer films (anils, conjugated polymers, polysilenes, heterocyclic compounds, betaine derivatives), coordination compounds and metal cluster compounds, and organometallic complexes of copper (II). Their behavior and physico–chemical properties are discussed.
Pigment Dispersions
Authors: Loebbert Gerd , Sharangpani Anand S. G. 
Published: July 2004

Abstract
A pigment dispersion, which is used to apply color to the surface of the substrate, such as ink film on paper or paint film on a steel surface, is a uniform distribution of very fine pigment. The quality of the dispersion is dependent on variables such as crystal growth, wetting of the pigment, and flushing of the pigment. Equipment used to make pigment dispersions include kneaders and internal mixers, close tolerance mills, high speed fluid energy mills, and sand, bead, and shot mill.
In the construction of a pigment dispersion, variables such as dispersion concentration and compatibility of the carrier are adjusted on the intended final use. Dispersions can be supplied as flushed pigments, chip dispersions, or color concentrates. The primary applications of the pigment dispersions are in the preparation of printing inks, paints and coatings, and plastics. Historically, the printing ink industry has been the leading consumer of pigment dispersions in the United States. Significant changes are expected in the manufacture and composition of pigment dispersions, in response to environmental and safety regulations and increasing public awareness.
Piping Systems
Authors: Handman Stanley E. 
Published: July 2004

Abstract
Many factors must be considered in the design of a piping system. These include the selection of the pipe material based on the design pressure and temperature and the corrosivity of the flowing material; the determination of the pipe size based on fluid mechanical considerations; and the application of valving. The ANSI/ASME B31 Code for Pressure Piping is delineated, with emphasis on the requirements of B31.3, the section covering chemical plant and refinery piping. Included are the mechanical and structural aspects of design; namely, the determination of pipe wall thickness, the design and selection of pipe supports, and the methods for ensuring that the piping has adequate flexibility to accommodate temperature changes and equipment settlement. Safety and environmental considerations are discussed.
Genetic Engineering, Plants
Authors: Edwards Janice W. , Kishore Ganesh M. , Stark David M. 
Published: July 2004

AbstractJANICEW. EDWARDS, GANESHM. KISHOREand DAVIDM. STARK(Monsanto Company)Several discoveries in the 1980s and 1990s permitted the transition of plant molecular biology from a fledgling science to commercial reality. These discoveries ranged from the identification of biologically important genes to the development of methods to introduce new genes into plants transformation and regulate gene expression. Nearly five dozen plant species have been transformed and the list of plant species subject to transformation include principal field crops such as corn, cotton, rape, rice, soybean, and wheat. In addition, several horticultural species such as tomato, potato, etc, have been subject to transformation. More than 500 field tests have been conducted and transgenic plants such as transgenic tomato, soybean, corn, rape, etc, are in the advanced stages of commercial development and regulatory process.Four methods have been extensively investigated for the introduction of transferred deoxyribonucleic acid (T‐DNA) into plants. Most common direct uptake of DNA by protoplasts, particle acceleration techniques such as electrostatic discharge or biolistics gun technology, and DNA uptake into partially digested immature embryos.Expression of genes that have been introduced into plants is regulated by promoters, although the extent of regulation of gene activity by the promoter is influenced at least to some extent by the insertion site of the gene within the chromosome. The choice of promoters is dictated by the tissue and developmental specificity required for gene expression. Two specific applications of plant biotechnology include engineering tolerance to the widely used herbicide glyphosate, C3H8NO5P, and increasing starch biosynthesis in plants. Both tomato fruit ripening and fruit firmness are among the advanced quality traits that are being investigated.
Plant Layout
Authors: E. Meissner Roland 
Published: July 2004

Abstract
This article discusses the process by which a plant plot plan is developed and the spacing and orientation between equipment. It describes the step‐by‐step procedures which a designer goes through in selecting the arrangement of equipment and providing the necessary space between the equipm ent items. Examples are included that illustrate the concepts presented. The article also presents an evaluation and discussion of the three principle types of layout presentations: orthographic drawings, plastic models, and computer‐aided design models. Practical uses and limitations of each of these presentation mediums are covered. Many practical design tips are included. Sufficient background information is provided for the reader to appreciate the subtleties of plant layout. The piperack design and its use as the arterial system for the plant are also covered.
Plant Safety
Authors: Prugh Richard W. 
Published: July 2004

Abstract
Health and safety of personnel and loss prevention are paramount concerns of the chemical industry. Several industry groups encourage members to improve the management of safety and improve manufacturing procedures and practices to minimize hazards. Moreover, state and federal authorities have legislated improvements for the safety of both employees and the public. Particular emphasis has been given to process safety in the legislation and in industry guidelines, and chemical manufacturers are required to follow detailed steps in ensuring adequate training, comprehensive operating procedures, thorough analysis of processes for hazards and investigation of accidents, diligent maintenance of facilities, well‐developed emergency plans, and self‐audits for compliance. Process safety management, including process production hazards and the various engineering and administrative controls, is discussed. The role of plant location, design and operation of facilities, and hazard prevention are presented, as are safe work practices and hazard analysis.
Plasticizers
Authors: Cadogan David F. , Howick Christopher J. 
Published: July 2004

Abstract

A plasticizer is a substance the addition of which to another material makes that material softer and more flexible. Most often plasticizers are materials which, when added to a polymer, cause an increase in the flexibility and workability, brought about by a decrease in the glass‐transition temperature,

T
g

, of the polymer. The most widely plasticized polymer is poly(vinyl chloride) (PVC) due to its excellent plasticizer compatibility characteristics, and the development of plasticizers closely follows the development of this commodity polymer. This article provides an overview of the important types of plasticizers which exist, and gives details of manufacture and how different production methods and starting materials affect the properties of the plasticizers. The mechanism of action of plasticizers is described, in terms of plasticization theory and the chemical modifications that occur during this process, which account for the excellent performance of some plasticizer molecules and the apparently poor softening ability of others. These effects are used to make products that are familiar to daily life and a change of plasticizer can produce changes in the properties of a wallcovering, a cable sheathing, etc. The current legislative and toxicological status of plasticizers are thoroughly reviewed to provide information about the environmental effects of this widespread use of these products.
Plasma Technology
Authors: Smith Mark D. 
Published: July 2004

AbstractPlasma can be broadly defined as a state of matter in which a significant number of the atoms and/or molecules are electrically charged or ionized, but the numbers of charges, both negative and positive, are equal. Plasma technology involves the use of these natural or artificially produced plasmas, whether gases, solid, or liquid. Plasmas range in size and density from wisps of interstellar matter to those that exist within the solids used in solid‐state technologies to those that are the unimaginably dense and hot interiors of stars. Plasmas can be as natural as lightning or the aurora borealis, or artificially produced, such as the flashes resulting from thermonuclear fusion experiments. Production of plasmas, modification and possible dissipation, as well as the diagnostics for examining plasmas of various types are included. Differences between gaseous plasmas and plasmas in condensed matter are examined. Uses of plasma include radiation sources, plasma chemistry, chemical analysis, plasma processing, surface modification, plasma polymerization, materials production, energy production, guns and missiles, explosives, weapons, communications, and space travel. Ongoing research in several areas points to a bright future for plasma technology.
Platinum‐Group Metals, Compounds
Authors: Giandomenico Christen M. 
Published: July 2004

AbstractThe platinum‐group metals, ruthenium, osmium, rhodium, iridium, palladium, and platinum, form binary compounds, coordination complexes, and organometallic compounds. Compounds of each of these metals, which exhibit a range of oxidation states, are summarized. Some of the more useful starting materials are noted, as are the most important uses for the compounds of each individual element. There are catalytic applications for the compounds of all six metals; chemotherapeutic applications for platinum compounds; oxidations by ruthenium and osmium compounds; plating and coating uses for platinum and palladium compounds; metal anode applications for iridium and rhodium compounds; and biological applications of ruthenium compounds. The economic aspects of the platinum‐group metal compounds are summarized, as are the most significant health and safety concerns of working with these compounds.
Platinum‐Group Metals
Authors: Seymour Richard J. , O'Farrelly Julia I. 
Published: July 2004

AbstractThe platinum‐group metals, ie, platinum, palladium, rhodium, ruthenium, osmium, and iridium, all have high melting points and exceptional corrosion resistance. Platinum, rhodium, and iridium are particularly stable to oxidation at high temperatures. These metals, especially platinum and palladium, show exceptional catalytic properties.In nature, platinum‐group metals frequently occur in conjunction with nickel, copper, and iron sulfides. The principal producing region is South Africa, but other commercially important deposits exist in Canada and CIS. In the refining of these metals, solvent extraction technology is increasingly replacing conventional hydrometallurgical processes. Benefits include increased recovery, improved efficiency, and significantly shortened process time. Resources and recovery processes are discussed.The platinum‐group metals are extensively used as catalysts. Applications include pollution control catalysts for gasoline and diesel vehicles, control of emissions of organics and nitrous oxides from industrial installations, fuel cells and process catalysts in the chemical industry, including nitric acid and chlorine production, and petroleum organic synthesis refining. Platinum‐group metals are also used as jewelry, in the glass industry, in electronic components, in spark plugs, on turbine blades, and in medical devices. Modern cardiovascular surgery and anticancer chemotherapy both employ these metals.
Plutonium and Plutonium Compounds
Authors: Morss Lester R. 
Published: July 2004

AbstractThe discovery of plutonium, its economic and military importance, sources, production, and nuclear properties are reviewed. The economic aspects of weapons‐grade and reactor‐grade plutonium are outlined. The preparation and properties of plutonium metal are discussed in detail. A presentation of the physical and chemical properties of atomic plutonium and stable plutonium ions is given. The complexation and hydrolysis properties of these ions are recapitulated. Analytical chemistry, separations technology, and metallurgy (including pyrometallurgical processing) are described. There is a brief treatment of storage and disposal of excess weapons plutonium. The chemistry of several classes of plutonium compounds is described: oxides, halides, oxyhalides, hydrides, carbides, silicides, nitrides, sulfides, and oxalates. The chapter concludes with a treatment of environmental, health, and safety aspects of plutonium. Vol. 19, pp. 407–443, 197 refs. through September 1, 1995.
Water, Pollution
Authors: Eckenfelder W. Wesley 
Published: July 2004

AbstractWater is omnipresent on earth, however, the volume of freshwater amounts to one thirtieth of the water of the salty oceans. This article describes the hydrologic parameters involved in storage and transport of freshwater. Water quality management standards, including EPA specified pollutants are identified. Treatment and techniques to control pollution include in‐plant waste control, minimization separations, adsorption, removal of heavy metals and toxic organics are given.
Fluorine‐Containing Polymers, Poly(Vinylidene Fluoride)
Authors: Dohany Julius E. 
Published: July 2004

AbstractThis article reviews the preparation, properties, and uses of poly(vinylidene fluoride) (PVDF or PVF2), including preparation of 1,1‐difluoroethene or vinylidene fluoride (VDF or), and commercially important copolymers of VDF with other fluorinated comonomers. PVDF is commercially produced by free‐radical‐initiated polymerization of VDF in emulsion or suspension. It has the characteristic resistance of fluoropolymers to harsh chemical, thermal, ultraviolet, weathering, and oxidizing environments. PVDF has exceptional resistance to high energy radiation. PVDF has high mechanical and impact strength, and excellent resistance to both creep under long‐term stress and fatigue. Structure and polymorphism of PVDF chains are reviewed. Thermodynamic compatibility of PVDF with other polymers and its solubility are reviewed. Fabrication and processing methods including extrusion, molding, coextrusion, and organosol dispersions are reviewed. Health and safety aspects of PVDF are outlined. Economic aspects of PVDF and cost are discussed. PVDF uses include long‐life exterior architectural finishes, wire and cable uses, fluid handling systems, microporous membranes, and piezoelectric and pyroelectric applications.
Polymethylbenzenes
Authors: Earhart H. W. , Komin Andrew P. 
Published: July 2004

AbstractPolymethylbenzenes are benzene derivatives that contain three to six methyl group substituents. Included are 1,3,5‐trimethylbenzene (mesitylene), 1,2,4‐trimethylbenzene (pseudocumene), 1,2,3‐trimethylbenzene (hemimellitene), 1,2,4,5‐tetramethylbenzene (durene), 1,2,3,5‐tetramethylbenzene (isodurene), 1,2,3,4‐tetramethylbenzene (prehnitene), pentamethylbenzene, and hexamethylbenzene. Physical properties, chemical properties, manufacture, production and shipping, specifications, health and safety factors, environmental considerations, uses, and derivatives are reviewed. The polymethylbenzenes are primarily basic building blocks for more complex chemical intermediates. Pseudocumene, mesitylene, and durene are used to produce polymer additives and intermediates, antioxidants, and agricultural chemicals.