bluuebunny/crossref_metadata_2025_split huggingface dataset:
Carbapenems and Penems
Authors: Southgate Robert , Osborne Neal F. 
Published: July 2004

AbstractIn the period up to 1970 most β‐lactam research was concerned with the penicillin and cephalosporin group of antibiotics. Since that time, however, a wide variety of new mono‐ and bicyclic β‐lactam structures have been described. The carbapenems originated from natural sources; the penem ring and its derivatives are the products of the chemical synthetic approach to new antibiotics. The chemical names are: 7‐oxo‐(R)‐1‐azabicyclo[3.2.0]hept‐2‐ene‐2‐carboxylic acid, C7H7NO3, and 7‐oxo‐(R)‐4‐thia‐1‐azabicyclo[3.2.0]hept‐2‐ene‐2‐carboxylic acid, C6H5NO3S, respectively. Carbapenems include thienamycin (C11H16N2O4S), MM 4550 (C13H16N2O9S2), MM 13902 (C13H16N2O8S2), MM 17880 (C13H18N2O2S2), PS‐5 (C13H18N2O4S), carpetimycin A (C14H18N2O6S), asparenomycin A (C14H16N2O6S), and pluracidomycin A (C9H11NO10S2). OnlyS. cattleyaandS. penemfacienshave been reported to give thienamycin. Thienamycin is isolated as a colorless, hygroscopic, zwitterionic solid. Carbapenems are extremely sensitive to many reaction conditions. Many derivatives of the amino, hydroxy, and carboxy group of thienamycin have been prepared primarily to study structure–activity relationships. One consequence of the discovery of the carbapenem natural products has been the development of new synthetic methods. Only chemical synthesis could provide the quantities ofN‐formimidoyl thienamycin (MK 0787) necessary for clinical trials and commercial production. A synthetic approach that involves the [3,4] bond formation using a carbene insertion reaction has been highly successful. A second method makes use of the lactone from acetone dicarboxylate. Thienamycin, the olivanic acids, and the majority of carbapenems are highly active broad‐spectrum antibiotics. Of the natural products, thienamycin is the most potent. Unlike carbapenems, no penems have been found in nature. The penem acid was shown to possess antibacterial activity in spite of its rather limited stability. Penems include SCH 29482 (C10H13NO4S2), SCH 34343 (C11H14N2O6S2), FCE 221201 (C10H12N2O6S), and others. 6‐Unsubstituted penems exhibit good activity against both gram‐positive and gram‐negative bacteria. Extensive carbapenem and penem antibiotic research has been ongoing since thienamycin was discovered in 1978. However, only the imipenem–cilastatin combination has become a commercial product. Meropenem was expected to be the second carbapenem on the market.
Metal Surface Treatments, Case Hardening
Authors: Brooks Charlie R. 
Published: July 2004

Abstract
The performance of many metallic components can be markedly improved by developing a surface region, the case, which is harder than that of the underlying region, the core. Case hardening processes, in which the original surface is an integral part of the case, may involve a physical or a chemical change at the surface. Processing may be accomplished through the use of heat or other methods such as plastic deformation or ion implantation. Small atoms, ie, first row elements, deposited in interstitial positions harden metallic components.
The various case hardening processes used for steels are discussed. Carburizing and nitriding, the most common methods employed, and the resultant case‐hardened steels are compared.
Castor Oil
Authors: Naughton Frank C. 
Published: July 2004

AbstractCastor oil, a renewable vegetable oil resource derived from the seed ofRicinus communis, is a versatile material that finds use as an industrial article of commerce. Castor oil is the only principal industrial oil that consists of 90% of the glyceride of a hydroxy acid, ricinoleic acid. The presence of the hydroxyl group in addition to the olefinic linkage, accounts for a unique combination of physical and chemical properties.World production, processing, and utilization of the oil to produce a variety of oleochemcals, are described as are the properties and chemical modifications of castor oil and its derivatives. Processes for recovery of the oil and meal, dehydration, polyamide polymer formation, sulfonation, alkali fusion, pyrolysis, hydrogenation, alkoxylation, and urethane reactions are discussed, and applications for the various materials are presented.
Catalysis, Phase‐Transfer
Authors: Dehmlow Eckehard Volker 
Published: July 2004

AbstractPhase‐transfer catalysis (PTC) is a method that allows reactions to occur in two‐phase systems in an easy and efficient way. Typically salts, dissolved in water or as solids, react with organic substances in organic nonpolar solvents. Catalysts are mostly quaternary ammonium or phosphonium salts, or polyethylene glycols. Alternatively, much more expensive crown ethers or cryptands are applied, predominantly for laboratory purposes. Mechanistically, most of the common PTC applications involve the extraction of anions into nonpolar organic media wherein they have much higher reactivities than under normal conditions as a result of lesser solvent interactions.Scope, mechanism, and examples of PTC are discussed, and the potential industrial importance of the method is stressed. Reactions that are mentioned in some detail include displacements, ester formation, ether formation, alkylation of carbanions, nucleophilic aromatic substitution, alkylation ofN‐heterocycles, polymerization of acrylates, oxidations, and carbene generation.
Catalysis
Authors: Gates Bruce C. 
Published: July 2004

AbstractCatalysis is the key to efficient chemical processing. Catalysts increase the rates of chemical reactions without affecting the equilibrium and, ideally, without being consumed. Catalysts work by forming chemical bonds with reactants and providing energetically favorable pathways for their conversion into products. This article is a summary of catalysis in solutions and on surfaces, including basic definitions and principles and numerous industrial examples; it is organized to emphasize the unity of the subject, direct the reader to the literature, and provide practical guidelines about technological applications.
Hydrocarbons, C
1
–C
6
Authors: Eastman Alan D. , Mears David 
Published: July 2004

Abstract
Eastman, Alan D. (Phillips Petroleum), and Mears, David E. (Unocal Corp.). This article covers the first three members of the alkane family, methane, ethane, and propane; the two isomeric butanes; the three isomeric pentanes; hexanes; and cyclohexane. Their properties, manufacture, and uses are described.Natural gas is the principal source of methanes, ethanes, and propane. Butanes are recovered from natural gas and petroleum refining streams. Pentanes occur in straight‐run gasoline and certain refining streams. Hexane and cyclohexane can be obtained from crude oil. High purity cyclohexane is made by hydrogenation of benzene.Principal uses of the alkanes are as fuels and as raw materials for essential chemical intermediates, notably ethylene from ethane and propane and nylon precursors from cyclohexane.
Cellulose
Authors: French Alfred D. , Bertoniere Noelie R. , Brown R. Malcolm , Chanzy Henri , Gray Derek , Hattori Kazuyuki , Glasser Wolfgang 
Published: July 2004

AbstractThis article covers nomenclature, sources, preparation, uses, microcrystalline cellulose, structural chemistry, reactions, solvents, and liquid crystals. Cellulose for commercial purposes comes mostly from wood and cotton, whereas cellulose for research comes from bacteria, algae, and ramie (also a textile fiber). Preparation includes pulping and purification, with an alternative method of steam explosion. The pore structure of cellulose is mentioned, along with the buildup of cellulose molecules into entire fibers. Emphasis is given to cellulose crystal structure. Recent research has provided structures with much better resolution for two crystal forms. Most native cellulose is a mixture of two crystalline phases. Cellulose solutions are important to the rayon and cellophane industries, and new solvents are of interest because they may lessen pollution and might permit commercial production of stronger cellulosic materials through the formation of liquid crystals. Figures include the chemical and physical structures of the molecule, including in solution, X‐ray diffraction patterns, the structure of a microfibril, and the unit cell structures of cellulose I–IV.
Cellulose Ethers
Authors: Majewicz Thomas G. , Podlas Thomas J. 
Published: July 2004

AbstractCellulose ethers is the common terminology for a group of cellulose derivatives that are soluble in aqueous or organic media. They are additives in many formulations and function primarily to control solution rheology. This article surveys the chemistry, properties, and characterization methods common to cellulose ethers and their manufacture and provides general health and safety factors. In the discussion of commercial cellulose ethers, greater detail for individual cellulose ether compositions, including carboxymethylcellulose, hydroxyethylcellulose and its mixed ethers, methylcellulose and its mixed ethers, ethylcellulose, hydroxyethylethylcellulose, and hydroxypropylcellulose is offered.
Fractionation, Blood, Cell Separation
Authors: Sibinga Theodore Hein Smit 
Published: July 2004

AbstractWith the advance of medical sciences, blood transfusion has transformed into blood component therapy. Human blood can be separated into its components, ie, red cells, white cells, platelets, and plasma; each serves its own function in the body. Minimizing risk of transmitting blood‐borne disease has driven blood transfusion toward maximizing the yield of a specific blood component from a specific blood donor. The blood component collected depends on need. Plasma is collected primarily for the procurement of coagulation factors, red cells are transfused in order to increase the oxygen carrying capacity of a patient, and platelets are applied to secure coagulation of the blood.Based on biological and physical differences between the blood components, technologies have been developed to separate blood from a blood donor or patient, collect those components needed for transfusion, and return the other components to the donor.Many cell separation methods are based on the formation of layers by mass density gradient using centrifugal separation chambers, eg, countercurrent separation and elutriation. The Beckman elutriation chamber and Haemonetics bowl technology are two such methods. Filtration technologies using advanced biomaterials are applied in the removal of leukocytes from red blood cell and platelet concentrates.
Centrifugal Separation
Authors: Letki Alan , Corner‐Walker Nick 
Published: July 2004

AbstractSeparation by density difference, compaction, and drainage is presented, along with formulas developed for bottle, solid wall, and disk centrifuges. The Σ‐concept is developed and several practical variants are discussed. Liquid–liquid separation interface location formulas are reviewed. Centrifuge components, including a breakdown of power and energy losses with applicable information for centrifuges, are represented. Centrifuge materials of construction and their corrosion, erosion, and strength characteristics are reviewed. Stresses generated owing to rotation and process materials; abrasion resistance, and noise generated by centrifuges are discussed. The various types of sedimentation and filtration equipment are reviewed. Examples of use, rates, and performance of bottle; disk; decanter; preparation; zonal; tubular; perforate basket; inverting filter; conical; and continuous single‐ and multiple‐stage pusher centrifuges are reviewed. For a brief discussion of gas centrifuges and their use in uranium enrichment, please see the previous editions.
Ceramics, Ceramic Processing
Authors: Ewsuk Kevin G. 
Published: July 2004

AbstractIn the manufacture of ceramic components, chemical composition and microstructure are specified to optimize the properties (eg, mechanical, electrical, and magnetic) of the finished product for a given application. Optimum properties are achieved by developing and refining processes to produce a target microstructure, and by controlling processes to minimize the concentration and scale of the defects in the finished part. The tolerance of the finished ceramic to defects determines the degree of control that must be exercised during processing.Ceramic component fabrication involves simultaneously optimizing multiple processes ranging from raw materials beneficiation to post‐sinter machining. To manufacture reliable ceramic components with reproducible properties, process–microstructure–property relationships must be understood and controlled during processing. These relationships can be determined by characterizing the ceramic raw materials, mixes, and the formed ceramic body intermittently during the various stages of processing and after final thermal consolidation. Established relationships between processing, microstructure, and properties can be applied to control manufacturing processes and optimize properties, and to identify and correct process deficiencies when less than optimal properties are obtained.
Cerium and Cerium Compounds
Authors: Kilbourn Barry T. 
Published: July 2004

AbstractCerium is the most abundant member of the lanthanide series, those elements having 4felectrons. It is found in nature in the presence of other lanthanides and this mix is often used commercially as a cerium source without separation. Mischmetal, a metallic mix of cerium and other of the lighter lanthanides, is used in the steel industry, in lighter flints, and as getters. Lanthanide concentrate, an oxide mix that includes cerium oxide, is used in some fluid cracking catalysts.Cerium is unique within the lanthanide series because it has two stable oxidation states. Many of the uses of cerium and cerium compounds center around the redox chemistry of the Ce(IV)/Ce(III) couple. Cerium oxide acts as a stabilizer improving oxidation resistance for alloy systems, polymers, and automotive catalytic converter catalysts. Cerium compounds are present in optical coatings, in phosphors for cathode ray tubes, and in paints.
Cesium and Cesium Compounds
Authors: Ferguson William , Gorrie Dena 
Published: July 2004

AbstractCesium is the most chemically active and rare of the naturally occurring Group 1 (IA) alkali metals. It is generally produced from pollucite by acid digestion to an intermediate cesium compound followed by thermochemical or electrolytic reduction. Production routes and properties of cesium and cesium compounds are described. Uses of cesium and cesium compounds continue to grow in electronics, in catalysts and organic synthesis, in analytical instrumentation, in biotechnology, and in medical applications. Cesium usage has also shown potential in such areas as magnetohydrodynamic power generation.
Chelating Agents
Authors: Howard William L. , Wilson David 
Published: July 2004

AbstractChelating agents or chelants are compounds having two or more donor atoms that can form cyclic coordination complexes or chelates with acceptor metals. The complexation is an equilibrium reaction that often strongly favors the complex. Chelating is used to modify or control the behavior of metals and their compounds by controlling the concentration of the metals in solution or to utilize the special properties of the chelation compounds. The active groups in chelants may be linear chains, eg, NCCN, macrocyclic rings, eg [OCC]n, or polycyclic structures, such as the cryptates, eg, X[CCYCC)n]3Y, where X and Y are bridgehead and donor atoms, respectively. Some pH, stability, solubility, and electrochemical relationships among simultaneous equilibria in chelation are shown. A broad range of applications based on concentration control, the special properties, and medical uses of chelation compounds are given. Metal sequestration, solubilization, and buffering are discussed as are metal extraction, precipitation, and displacement. Economic data for industrial chelating agents are given. Use of chelating agents is essentially benign environmentally and presents little or no hazard to health or safety under normal conditions of use and handling.
Chemiluminescence, Analytical Applications
Authors: Nakashima Kenichiro 
Published: July 2004

AbstractChemiluminescence (CL) has many advantageous features as a tool of detection in instrumental analysis, including sensitivity, selectivity and simplicity. A CL reaction needs no excitation light source, thus, it is not accompanied with any scattering light. This results in a large signal‐to‐noise (S/N) ratio and consequently, a substantial increase in detector's sensitivity. To date, several kinds of CL reactions have been clarified on their reaction mechanisms. Generally, concentrations of the substrates or catalysts in each CL reaction can be determined by measuring the CL generated. Among the CL reactions, luminol (5‐amino‐2,3‐dihydro‐1,4‐phthalazinedione) derivatives, acridine derivatives, aryloxalate derivatives, and ruthenium derivatives have frequently been utilized in analytical applications. In this article, representative analytical applications of CL in liquid phase for the determination of a variety of compounds are described.
Chemicals from Brine
Authors: Butts David 
Published: July 2004

AbstractOver a billion tons of brine are handled yearly by industries to produce minerals and chemicals. This makes it one of the largest processed ores in the world. These minerals and chemicals are used in the processing of fertilizers, detergents, paper, plastics, preservatives, foodstuffs, pharmaceuticals, metals, and glass. Sodium chloride alone is used in 14,000 different products.Compounds of boron, bromine, calcium, iodine, lithium, magnesium, potassium, and sodium are all produced from brine. There is an endless supply of some of these chemicals in the oceans. Most of the brine is concentrated by solar evaporation in shallow ponds that saves energy and eliminates pollution by not burning fossil fuel.
Metal Surface Conversion Treatments
Authors: Petschel Michael , Hart Robert 
Published: July 2004

Abstract
Metals, important materials for construction and manufacture, corrode in certain environments limiting the lifetime of manufactured metal goods. To protect from corrosion and to confer paint adhesive properties to metal surfaces, chemical pretreatment conversion coatings are widely used.
The most common metal surface treatments are iron, zinc, or chromium phosphating, chromating, and anodizing. An overview of the mechanism of coating formation, process operation and control considerations, coating characteristics, coloring procedures, and important applications for various coatings is given. Environmental considerations for chemical conversion coatings and by‐products of conversion coating operations are also discussed.
Chlorosulfonated Polyethylene
Authors: Ennis Royce 
Published: July 2004

AbstractChlorosulfonated polyethylene represents a group of chemically modified polyolefins containing pendent chlorine and sulfonyl chloride groups and having useful synthetic elastomer properties. They are derived from the action of a mixture of chlorine and sulfur dioxide, sulfuryl chloride and a weak base, or sulfuryl chloride and chlorine on preformed polyolefin polymers in the presence of an initiator. Although the reaction is normally carried out batchwise in a carbon tetrachloride solution, other solvents and process schemes have been successfully used. The resulting polymer may contain 20–60% chlorine and 1–5% sulfur as sulfonyl chloride groups. The pendent chlorine atoms serve to destroy the parent polymer crystallinity and impart useful chemical properties such as resistance to oil, oxidizing chemicals, ozone, and heat. The sulfonyl chloride groups react with divalent metal oxides, sulfides, or radical traps to form stable cross‐links. The raw polymer and vulcanizate mechanical properties are controlled by the molecular weight, molecular‐weight distribution, and chain branching of the parent polyolefin.The technology has been extended to include copolymers and functionally grafted homopolymers as base resins. These new types, along with extensive studies combining the flexibility of the sulfonyl chloride cure site with specific cross‐linking agents, stabilizers, and reinforcing agents, have produced a broad array of useful products, ie, coatings, adhesives, hose, tubing, automotive belts, etc.
Chlorosulfuric Acid
Authors: McDonald C. E. 
Published: July 2004

AbstractChlorosulfuric acid, more widely known as chlorosulfonic acid, is a strong mineral acid made by reacting equimolar quantities of hydrogen chloride and sulfur trioxide. Its structure is analogous to sulfuric acid: the chloride replaces a hydroxyl group. Chlorosulfuric acid is a highly reactive chemical used principally in organic synthesis as a sulfating, sulfonating, or chlorosulfonating agent. Its main applications are an intermediate in the production of synthetic detergents, surfactants, and pharmaceuticals. It is also used in the production of dyes and pigments, ion‐exchange resins, pesticides, and plasticizers.Commercial‐grade chlorosulfuric acid has a purity of 99+%. When exposed to the atmosphere, it reacts with the moisture present to form dense white clouds of sulfuric acid and hydrochloric acid mists. It has been used as a smoke screen in wartime.
Chloric Acid and Chlorates
Authors: Mendiratta Sudhir K. , Duncan Budd L. 
Published: July 2004

AbstractSodium chlorate is the primary raw material for the manufacture of chlorine dioxide, a bleaching agent in the pulp and paper industry. Chlorine dioxide substitutes for chlorine in pulp bleaching, most ore of the sodium chlorate produced is used in the bleaching process. Sodium chlorate is prepared electrolytically. The modern technology described minimizes sodium chloride and sodium dichromate impurities. Chlorates are powerful oxidizers, and they are also used in perchloric salt and uranium production. They are strong irritants.Chloric acid technologies have been developed which allow the generation of chlorine dioxide directly from the acid, without the formation of sodium salts in the generator.
N‐Halamines
Authors: Worley S. Davis , Wojtowicz John A. 
Published: July 2004

AbstractN‐Halamines are inorganic and organic compounds in which oxidative halogen is chemically bonded to nitrogen. They have both research and commercial importance, particularly in the areas of disinfection of water and stabilization of free halogen. TheN‐halogen bond is formed by reaction of an amine, imine, amide, or imide with halogen, hypohalous acid, or hypochlorite. Only the chloro and bromo derivatives are of commercial importance. The physical and chemical properties, preparation, manufacture, uses, safety and handling, toxicity, and economic aspects of chloramines and bromamines are discussed. The chemistry of chloramines and bromamines is diversified not only because nitrogen and halogen act as reaction sites, but because of the different modes by which these functionalities react. Research activity on synthetic applications of chloramines and bromamines continues to be high.In aqueous solution, the chloramines and bromamines generally undergo hydrolysis to varying degrees forming hypochlorous and hypobromous acids. Thus generally theseN‐halamines can be considered as halogen release agents, and many, eg, chloroisocyanurates, find use in bleaching, disinfecting, and sanitizing applications. Others, such as halogen derivatives of ammonia, are important because they are industrial process intermediates (monochloramine) or of significance in water treatment (mono‐, di‐, and trichloramine). The most recent work has concerned covalent attachment ofN‐halamine moieties to insoluble polymers so as to create biocidal materials with excellent potential for commercial utilization.