bluuebunny/crossref_metadata_2025_split huggingface dataset:
Process Energy Conservation
Authors: Steinmeyer Dan 
Published: July 2004

Abstract
Increased energy conservation comes from broadscale technological progress such as a mix of better hardware, improved catalysts, computer process control, and optimized design. These cause energy efficiency to improve in times of both rising and falling energy prices. In times of rising energy prices, the trade of capital for energy is also important. Principal elements of energy efficient design are optimization of separation systems, including distillation and other techniques; heat‐exchange technology; refrigeration; pressure drop; and steam and condensate systems.

An overall process energy balance serves as a framework during design and after start‐up to optimize energy usage. A more fundamental analysis stresses minimizing the loss of work potential. In separation, efficiency results from low driving forces achieved by multistage processes, hence distillation is dominant. Special separations are usually only economical when removing a relatively dilute component. Heat interchanger capital, together with Δ
T
and Δ
P
costs, dominates many process. Δ
T
has a greater economic impact on the cost of the heat‐exchange surface than does Δ
P
. Methods are given for Δ
T
and Δ
P
selection. Energy efficiency needs to be carefully integrated with the process to maintain reliability and safety.
Polyethers, Propylene Oxide Polymers
Authors: Gagnon Steven D. 
Published: July 2004

AbstractPropylene oxide and other epoxides under go homopolymerization to form polyethers. In industry the polymerization is started with multifunctional compounds to give a polyether structure having hydroxyl end groups. The hydroxyl end groups are utilized in a polyurethane forming reaction. This article is mainly concerned with propylene oxide and its various homopolymers that are used in the urethane industry.The polymerization of propylene oxide can be catalyzed by base (used commercially), acid (for glycol synthesis), and by coordination catalysts containing Al, Zn, or Fe as the central atom. The mechanism of base‐catalyzed polymerization is reviewed. The physical properties of poly(propylene oxide) as well as the physical methods for determining them are reviewed. Particular emphasis is placed on nmr which has yielded a wealth of information about the structure of poly(propylene oxide) and copolymers of propylene oxide and ethylene oxide.
Graphite, Properties of Artificial
Authors: Hupp T. R. 
Published: July 2004

AbstractThe graphite crystal, the fundamental building block for manufactured graphite, is one of the most anisotropic bodies known. Anisotropy is the direct result of the layered structure with extremely strong carbon–carbon bonds in the basal plane and weak bonds between planes. Manufactured graphite is semimetallic in character. Conduction is by means of an approximately equal number of electrons and holes that move along the basal planes. Manufactured graphite is strongly diamagnetic. Compared with other refractories, graphite has an unusually high thermal conductivity near room temperature; above room temperature, the conductivity decreases exponentially to approximately 1500°C. The volumetric thermal expansion (VTE) of manufactured graphite is anomalously low when compared to that of the graphite single crystal. The low value of volume expansion of most manufactured graphite has been related to the microporosity within the coke particles. Graphite reacts with oxygen to form CO2and CO, with metals to form carbides, with oxides to form metals and CO, and with many substances to form laminar compounds. Of these reactions, oxidation is the most important to the general use of graphite at high temperatures.
Propellants
Authors: Lindner Victor 
Published: July 2004

AbstractPropellants are mixtures of chemical compounds that produce large volumes of high temperature gas at controlled, predetermined rates, and can sustain combustion in the absence of atmospheric oxygen. Principle applications are in the launching of projectiles from guns, rockets, and missile systems. Propellant‐actuated devices are used to drive turbines, move pistons, pump fluids, shear bolts and wires, eject pilots and jettison stores from aircraft, and act as a source of heat in special devices. Solid propellants are compact, have a long storage life, and may be handled and used without exceptional precautions.Propellants, most often based on nitrocellulose, also contain an oxidizer, binder, and sometimes a metallic fuel. Double‐based propellants also have liquid energetic plastizers. Triple‐based propellants contain crystalline additives. Composition, properties, and manufacture of the various propellants are described. Nonconventional propulsion methods are also discussed.
Water, Properties
Authors: Morgan James J. , Stumm Werner 
Published: July 2004

Abstract
The physical‐chemical properties of water as a solvent are tabulated. The magnitude of the main reservoirs and fluxes in the hydrological cycle, with special attention given to the human appropriation of renewable fresh water, are given. The acquisition of solutes in the water is discussed in the context of circulation of water with rocks, atmosphere, and biota, with special attention given to chemical weathering, the biogeochemical cycle, chemical equilibria, and the chemical speciation of the elements.
Biomaterials, Prosthetics, and Biomedical Devices
Authors: Szycher Michael , Qiu Jinhao , Tanaka Mami 
Published: July 2004

AbstractProsthetics or biomedical devices are objects which serve as body replacement parts or as tools for implantation of such parts. Such devices are prepared from a variety of materials including metals, plastics, other polymers, and ceramics. Devices for cardiovascular and orthopedic problems are discussed herein as are bioresorbable polymers used for sutures.Biomedical applications of smart materials can be divided into three categories: (1) implants and stents, such as bone plates and marrow needles; (2) surgical and dental instruments, devices, and fixtures, such as orthodontic fixtures and biopsy forceps; and (3) devices and instruments for medical checkups, such as ultrasonic devices. The applications of the first category require strict biocompatibility of a material because it is implanted in the body for long periods. Among many traditional materials, including metals, alloys, and ceramics, that are available commercially, only a limited number are currently used as prostheses or biomaterials in medicine and dentistry. The applications in the second category require excellent mechanical characteristics as well as biocompatibility. The third category is used mainly for transducers.Among smart materials, the Ti–Ni shape‐memory alloy (SMA) has attracted the most attention for biomedical applications in the first and second categories due to its excellent biocompatibility and mechanical characteristics. Research on biomedical applications of the SMA started in the 1970s with animal experiments initially, followed by clinical tests. The first example of a successful biomedical application of the SMA was a bone plate, which was used to repair broken bones. Now, many medical and dental applications of SMAs are available, and many new applications are being developed. On the other hand, piezoelectric materials have been widely used as transducers for medical ultrasonic devices due to their sensor function that uses piezoelectricity and the actuator function that uses inverse piezoelectricity.
Proteins
Authors: Nambudripad Raman , Smith Temple F. 
Published: July 2004

Abstract
Nambudripad, Raman (Beth Israel Hospital), and Smith, Temple F. (Boston University). Proteins are biopolymers built up from 20 different amino acids. Their diversity derives from the different combinations of the amino acids which form the sequence. The function of a protein depends on its unique three‐dimensional structure, which is itself determined by the amino acid sequence. The principal forces that drive proteins to their folded structure are the hydrophobic effect and backbone hydrogen bonding. The latter gives rise to the two elements of secondary structure, α‐helix and β‐sheet, commonly observed in proteins. The number of ways that these structures can pack is finite, giving rise to a limited number of folding motifs which recur in proteins of even unrelated structure. The function of proteins is carried out by a few residues in an active site which interacts with other molecules. Prediction of protein structure from its amino acid sequence is an active area of research. Different approaches include energy minimization, comparative modeling, and inverse protein folding. Progress in molecular biology and molecular modeling have made the study of the function and design of proteins a reality.
Pulp Bleaching
Authors: Ni Yonghao , Liu Zhong 
Published: July 2004

Abstract
Pulp fibers currently produced from the pulp and paper industry can be classified into three different kinds: chemical pulps, mechanical pulps, and deinked (recycled) pulps. The principle objective of bleaching any type of pulp is usually to increase the pulp brightness, which is defined as reflectance measured at a wavelength of 457 nm. However, the strategy and detailed processes are different for different pulps. This information is given in this article.
Pyrazoles, Pyrazolines, and Pyrazolones
Authors: Kornis Gabe I. 
Published: July 2004

Abstract
The title compounds are five‐membered heterocycles having two adjacent nitrogen atoms within the ring. Pyrazoles have two endocyclic bonds and possess aromatic and tautomeric properties. Pyrazolones also have two double bonds, one of which is attached to an exocyclic oxygen atom. Pyrazolines have only one endocyclic double bond. The structural elucidation of pyrazoles and derivatives has been greatly aided by nuclear magnetic resonance spectroscopy, especially for distinguishing between isomeric structures. Pyrazoles are stable compounds and their boiling points increase with an increase in the number of alkyl groups on carbon; solubility in organic solvents is also increased. Substitution on nitrogen decreases the boiling point because of the elimination of hydrogen bonding. Pyrazolines are usually liquids having high boiling points and low water solubility, and are basic in nature. Pyrazolones are often crystalline solids and their characteristics are strongly influenced by the predominant tautomeric form. Pyrazoles can react with both acids and bases, and can be halogenated, nitrated, and acylated on both N and C. Pyrazolines are much less stable, resulting in facile ring opening. Pyrazolones react with diazonium salts, an important process in the dye industry. The preferred synthetic method for the title compounds utilizes the reaction of hydrazines with bifunctional compounds, such as β‐diketones and esters, and β‐keto acetylenic compounds. In an alternative procedure, diazo compounds replace hydrazines and ring formation takes place via 1,3‐dipolar cycloaddition. Pyrazoles and pyrazolones are widely used in the pharmaceutical industry to alleviate inflammation, fever, pain, and infections. To a lesser extent, they are also used as insecticides and herbicides. Pyrazolones linked to azo compounds are extensively used in the dye industry; some pyrazolines display insecticidal activity.
Pyridoxine (B6)
Authors: Burdick David 
Published: July 2004

AbstractVitamins (Pyridoxine–B6). Burdick, David (Hoffmann‐La Roche Inc.). Vitamin B6consists of a group of six biochemically interconvertible substances, pyridoxine, pyridoxol, pyridoxamine, and their 5′‐phosphates. These are found in the tissues and fluids of virtually all living organisms. Pyridoxal phosphate plays essential roles in over 100 enzymes involved with amino acid biochemistry. Humans and animals cannot biosynthesize vitamin B6and require it in their diets or in supplements to prevent a number of metabolic and neural disorders. Humans require 2 mg/d in their diets. Chemical interactions with some food and drug components can reduce bioavailability of vitamin B6.Pyridoxine is the most stable of the B6vitamers. It is quite stable when dry or in acidic solution but degrades with base or irradiation. Production from natural sources or bioprocesses is not practical. All of the more than 3000 t/yr world production is made by chemical synthesis by variants of a cycloaddition route of substituted oxazoles with butenediol derivatives. Pyridoxine hydrochloride is widely used in foods, feeds, and multivitamin supplements.Essentials of the history, occurrence, biosynthesis, biochemical and physiological functions, chemical transformations, manufacturing chemistry, analytical methods, safety and handling, product forms, and uses of vitamin B6are briefly reviewed.
Pyridine and Pyridine Derivatives
Authors: Scriven Eric F. V. , Toomey Joseph E. , Murugan Ramiah 
Published: July 2004

AbstractScriven, Eric F. V., Toomey, Joseph E., Jr., and Murugan, Ramiah (Reilly Industries, Inc.). Commercial manufacture, industrial chemistry, and market uses of pyridine and pyridine compounds are reviewed. Pyridines often serve as intermediates for manufacture of products that are bioactive, such as medicinals, herbicides, insecticides, and fungicides. Significant end products for these market applications are identified. Important physical properties are also listed. Discussion of manufacture includes raw materials used, energy utilization, economics, toxicity of compounds, and safety factors. Vol. 20, pp. 641–679, 110 refs. to September 1994.
Pyrrole and Pyrrole Derivatives
Authors: Anderson Lowell Rr , Liu Kou‐Chang 
Published: July 2004

AbstractPyrrole is a planar, aromatic, five‐membered heterocycle which provides the fundamental structural subunit for many of the most important biological molecules, such as heme and chlorophyll. Extensive delocalization of the lone pair of nitrogen electrons throughout the system accounts for the lack of basicity and pronounced aromatic character of pyrrole systems.Pyrrole derivatives are often prepared by condensation of amines with carbonyl‐containing compounds. Several widely used synthetic reactions that are variations of this procedure are discussed. These include the reaction of an α‐aminoketone with β‐dicarbonyls (Knorr), the condensation of an α‐haloketone with a β‐ketoester in the presence of an amine (Hantzsch), and the condensation of a 1,4‐diketone with ammonia or a primary amine (Paal‐Knorr).Brief descriptions of the preparation and utility of some of the very large number of pyrrole derivatives are provided. These include the hydroxypyrroles, as well as aldehydes, ketones, acids, esters, and various reduced forms, such as pyrrolines and pyrrolidines. Condensed pyrroles with two, three, or four pyrrole nuclei are well known, as are the larger polypyrroles. Polypyrroles form highly stable, flexible films which are electrically conducting.Pyrrolidinones are five‐membered nonaromatic cyclic amide systems prepared by the reaction of butyrolactone with ammonia or a primary amine at relatively high temperatures. Several are commercially available and are widely used as intermediates, wetting agents, and solvents with relatively low toxicity. The important monomer 1‐vinyl‐2‐pyrrolidinone is derived from 2‐pyrrolidinone.
Quality Control
Authors: Silverstein Irwin 
Published: July 2004

Abstract
Quality in the chemical industry has come to encompass three areas: quality control, quality assurance, and quality systems. The importance of quality to the chemical industry is in its use as a competitive tool in international trade. Historically, industrial quality issues in the twentieth century were emphasized in Japan to reduce costs and improve product quality. Quality improvement activities can often lead to a large corporate economic gain.
Quality control responsibilities involve issues such as sampling plans, calibration, and replicate analyses. Statistical quality control and laboratory information management systems are often employed. Quality assurance, which encompasses quality control, covers such activities as employee training, quality system documentation, preparation and transfer of test methods, and applying the tools of quality, quality audit, and customer complaints.
Different systems are compared. The product quality system Good Manufacturing Practices, the quality system ISO 9000 standard, and the quality performance recognition of the Malcolm Baldridge National Quality Award are discussed.
Radiopharmaceuticals
Authors: Lazewatsky Joel L. , Crane Paul D. , Edwards D. Scott 
Published: July 2004

Abstract
Radiopharmaceuticals are radioactive drugs used as imaging and therapeutic agents in nuclear medicine. Commonly performed clinical studies are discussed and the approved radiopharmaceuticals are presented in terms of biological distribution, disease targets, and chemical and physical properties. Advantages and disadvantages of nuclear medicine techniques are presented.

The second section comprises a discussion of isotopes used in both diagnostic and therapeutic nuclear medicine. Specific properties as well as usage and means of production are given. The chemistry of radiopharmaceuticals including synthesis, labeling, and analysis is presented followed by discussion of the instrumentation used for both
in vivo
and sample measurement of radioactivity. Measurements of dispensed doses are described as are imaging systems and instruments for radiation safety. Radiopharmaceutical safety issues, including both radiation dosimetry and a brief discussion of chemical toxicity, are presented and formulation and packaging of materials is discussed. Anticipated developments and new directions for the industry are presented.
Radiation Curing
Authors: McGinniss Vincent D. 
Published: July 2004

AbstractThe interaction of electromagnetic radiation with organic substrates is of widespread interest and has broad commercial applications. The use of electromagnetic radiation to alter the physical and chemical nature of a material is sometimes termed radiation curing technology. In radiation curing, electromagnetic radiation interacts with organic substrates to develop cross‐linked or solvent‐insoluble network structures. For example, a preformed thermoplastic polymer that interacts directly with certain types of ionizing (high energy) radiation from a given source of energy can develop into cross‐linked or network structures having higher melting points, improved heat resistance, and better chemical resistance than the original thermoplastic polymer starting materials. Similar types of high energy radiation can be used to cross‐link (cure) organic coatings, provided that the liquid coating composition contains reactive vinyl‐unsaturated components such as allyl, acrylate, methacrylate, styrene, and fumarate reactive groups.Radiation curing technology involves consideration of at least four main variables: type of radiation source; organic substrate to be irradiated; kinetics and mechanisms of radiation energy–organic substrate interactions; and the final chemical, physical, and mechanical properties associated with the formation of three‐dimensional (cured) network structures. The conversion of electrical energy into infrared, ultraviolet, and high energy electromagnetic radiation has gained worldwide acceptance as an efficient and economical method for modifying polymeric materials. These radiation‐modified polymer systems are associated with many different types of products produced under a wide diversity of manufacturing operations.
Reactor Technology
Authors: Tarmy Barry L. 
Published: July 2004

AbstractReactor technology presents an overview of the underlying principles of chemical reaction engineering and the practices used in their application. Central to the commentary are the varied nature of chemical reactors, operating conditions, external operating environments, developmental history, industrial application, and evolutionary changes in the context of feed supply and reactant requirements, production and product specifications, fixed and operating costs, process integration, safety concerns, and environmental considerations. The principal reactor types and their characteristics are presented along with selection, development, and design considerations, and descriptions of the complex flow behavior within reactors. Also covered are the changing roles of computer simulation of reactor performance, laboratory experimentation, pilot‐plant usage, and scale‐up methodology. Following these expositions is a survey of industrial reactor usage by reactor type, which features selected examples of batch and semibatch reactors, continuous‐flow stirred‐tank reactors, thermal tubular reactors, bubble columns, airlift reactors and spray columns, tubular fixed‐bed reactors, single‐ and multiphase fixed beds, and fluid‐bed and gas–liquid–solid fluidization reactors.
Petroleum Refinery Processes
Authors: Speight James 
Published: July 2004

Abstract
Petroleum refining or petroleum processing is the recovery and/or generation of usable or salable fractions and products from crude oil, either by distillation or by chemical reaction of the crude oil constituents under the effects of heat and pressure. Petroleum refining also involves treating the raw products by a variety of finishing processes to yield marketable products.
A refinery is an integrated group of manufacturing plants that vary in number according to the variety of products produced; it must be flexible and able to change operations as needed. Refinery processes must be selected to produce products according to demand.
This article deals with the processes used to refine petroleum, from the initial pretreating of the well fluids to the finishing processes for products as well as the gas treating processes for reducing emissions to the environment.
Fibers, Regenerated Cellulose
Authors: Woodings Calvin 
Published: July 2004

AbstractFibers manufactured from cellulose are either derivative or regenerated; historically they are designated man‐made fibers and distinguished from fibers based on synthetic organic polymers. A derivative fiber is one formed when a chemical derivative of a natural polymer, eg, cellulose, is prepared, dissolved, and extruded as a continuous filament, and the chemical nature of the derivative is retained after the fiber formation process. A regenerated fiber is one formed when a natural polymer, or its chemical derivative, is dissolved and extruded as a continuous filament, and the chemical nature of the natural polymer is either retained or regenerated after the fiber formation process. The difficulties of making solutions of natural cellulose from which fibers can be spun has led to most fabricated cellulosic fibers being regenerated from more readily soluble derivatives of cellulose. It is the technology of making these fibers that is the subject of this article.Textile fibers and filaments composed of regenerated cellulose are called rayons. In Europe the fibers are now generally known as viscose; the term viscose rayon is used whenever confusion between the fiber and the cellulose xanthate solution (also called viscose) is possible. In addition to the viscose process, the cuprammonium rayon and direct dissolution processes are also covered. Fiber properties and environmental and commercial issues are discussed.