bluuebunny/crossref_metadata_2025_split huggingface dataset:
Magnetic Neutron Scattering
Authors: Lynn J.W. 
Published: October 2003

AbstractThe neutron is a spin‐particle that carries a magnetic dipole moment of −1.913 nuclear magnetons. Magnetic neutron scattering then originates from the interaction of the neutron's spin with the unpaired electrons in the sample, either through the dipole moment associated with an electron's spin or via the orbital motion of the electron. The strength of this magnetic dipole‐dipole interaction is comparable to the neutron‐nuclear interaction, and thus there are magnetic cross‐sections that are analogous to the nuclear ones, which reveal the structure and dynamics of materials over wide ranges of length scale and energy. Magnetic neutron scattering plays a central role in determining and understanding the microscopic properties of a vast variety of magnetic systems—from the fundamental nature, symmetry, and dynamics of magnetically ordered materials—to the elucidation of the magnetic characteristics essential in technological applications.One traditional role of magnetic neutron scattering has been the measurement of magnetic Bragg intensities in the magnetically ordered regime. Such measurements can be used to determine the spatial arrangement and directions of the atomic magnetic moments, the atomic magnetization density of the individual atoms in the material, and the value of the ordered moments as a function of thermodynamic parameters such as temperature, pressure, and applied magnetic field. These types of measurements can be carried out on single crystals, powders, thin films, and artificially grown multilayers, and often the information collected can be obtained by no other experimental technique. For magnetic phenomena that occur over length scales that are large compared to atomic distances, the technique of magnetic small angle neutron scattering (SANS) can be applied, in analogy to structural SANS. This is an ideal technique to explore domain structures, long wavelength oscillatory magnetic states, vortex structures in superconductors, and other spatial variations of the magnetization density on length scales from 1 to 1000 nm. This particular technique has enjoyed dramatic growth during the last decade due to the rapid advancement of atomic deposition capabilities.Neutrons can also scatter inelastically, to reveal the magnetic fluctuation spectrum of a material over wide ranges of energy and over the entire Brillouin zone. Neutron scattering plays a truly unique role in that it is the only technique that can directly determine the complete magnetic excitation spectrum, whether it is in the form of the dispersion relations for spin wave excitations, wave vector and energy dependence of critical fluctuations, crystal field excitations, magnetic excitons, or moment fluctuations. In this overview we will discuss some of these possibilities are discussed.
Electrical Measurements on Superconductors by Transport
Authors: Schwartz Justin , Weijers Hubertus W. 
Published: October 2003

Abstract
This article focuses on techniques for measuring the electrical behavior of technologically important superconducting wires, tapes, and other conductors. Depending on the conditions of measurement, electrical behavior can be interpreted to obtain many technologically important quantities. The interpretation for some of the most common of these quantities are discussed.
When characterizing the electrical behavior of superconductors, it is primarily the voltage‐current relationships that are measured. All other quantities are derived from these. Background conditions for the measurements, including temperature, magnetic field, and stress‐strain state, vary with the specific measurement and type of information being sought.

The most common parameter to be obtained from a transport current‐voltage measurement is the transport critical current (

), which is the maximum current that can be carried by the superconductor in the superconducting state. Often this is determined as a function of temperature and magnetic field. Critical current and the corresponding critical current density (

) are the most important parameters in determining the utility of a superconducting material for applications. The value of

equals

normalized by the cross‐sectional area perpendicular to the direction of the current flow. This area can be defined by a variety of methods that are discussed.

Electrical measurements of transport current are used to determine the critical temperature (

) of the superconductor. This is the temperature below which the material enters the superconducting state and above which it is in the normal state. By measuring

as a function of magnetic field using such an electrical measurement, one can also learn about the magnetic behavior of a high‐temperature superconductor.

Electrical measurements are used to determine the properties of superconductors beyond the superconducting state. Measurements of the resistivity versus temperature (i.e., the current‐voltage relationship as a function of temperature in the normal state) are important for the design of superconducting current leads and magnets. For cables and coils, electrical measurements provide insight into the stability and quench propagation (sudden reversion to the normal state from the superconducting state) behavior. This information is key for the design of a superconducting magnet.
Electrical measurements can be used to estimate the AC losses (i.e., energy dissipation resulting from an alternating current) in a superconducting wire or cable. In this case, the hysteretic behavior is used to estimate the energy dissipation.

This article concentrates on techniques for measuring the current‐voltage (

) relationship in superconducting wires, tapes, and cables. Important differences between LTSs and HTSs are discussed. Emphasis is placed on the

measurement and on the interpretation of the results in the context of the technical information sought from the particular experiment.
Single‐Crystal X‐Ray Structure Determination
Authors: Jacobson Robert A. 
Published: October 2003

AbstractX‐ray techniques provide one of the most powerful, if not the most powerful, methods for deducing the crystal and molecular structure of a crystalline solid. In general, it is a technique that provides a large number of observations for every parameter to be determined and results obtained thereby can usually be considered very reliable. Significant advances have taken place, especially over the last twenty years, to make the collection of data and the subsequent steps to carry out the rest of the structure determination amenable to the relative novice in the field. This has led to the adoption of single‐crystal diffraction methods as a standard analytical tool.It Modern crystallography is strongly dependent on the use of the digital computer. Typically, a small single crystal (a few tenths of a millimeter in dimension) of the material to be investigated is placed on a diffractometer and data are collected under computer‐controlled operation. A moderate‐sized unit cell (10 to 20 Å on edge) can yield 5000 or so diffraction maxima, which might require a few day's data collection time on a scintillation counter diffractometer or only hours of data collection time on the newer charge‐coupled device (CCD) area detectors.From these data the fractional coordinates describing the positions of the atoms within the cell, some characteristics of their thermal motion, the cell dimensions, the crystal system, the space group symmetry, the number of formula units per cell, and a calculated density can be obtained. This “solving of the structure” may only take a few additional hours or a day or two if no undue complications occur.This article concentrate on the use of X‐ray diffraction techniques as would be necessary for the normal crystal structure investigation. A discussion of the basic principles of single‐crystal X‐ray diffraction is presented followed by a discussion of the practical applications of these techniques. In the course of this discussion, a few of the more widely used methods of overcoming the lack of measured phases, i.e., the “phase problem” in crystallography, are presented. These methods are usually sufficient to handle most routine crystal structure determinations. Space will not permit discussion of other more specialized techniques that are available and can be used when standard methods fail.
Single‐Crystal Neutron Diffraction
Authors: Koetzle Thomas F. 
Published: October 2003

Abstract
This article outlines the basic principles of single‐crystal neutron diffraction measures the elastic Bragg reflection intensities from crystals of a material, the structure of which is the subject of investigation. A single crystal is placed in a beam of neutrons produced at a nuclear reactor or at a proton accelerator‐based spallation source. Single‐crystal diffraction measurements are commonly made at thermal neutron beam energies, which correspond to neutron wavelengths in the neighborhood of 1 Å. For high‐resolution studies requiring shorter wavelengths (∼0.3 to 0.8 Å), a pulsed spallation source, or a high‐temperature moderator (a “hot source”) at a reactor may be used. When complex structures with large unit‐cells are under investigation, as is the case in structural biology, a cryogenic‐temperature moderator (a “cold source”) may be employed to obtain longer neutron wavelengths (∼4 to 10 Å). A monochromatic beam technique is generally used at reactors, which normally operate as continuous wave (CW) neutron sources. At spallation sources, which normally are pulsed, a time‐of‐flight Laue method with a broad range of neutron wavelengths is generally used, and the neutron wavelength is determined from the time‐of‐flight for neutrons to reach the detector. The type of moderator is again generally optimized for the particular application, in a manner similar to what is the common practice at reactors.
A single‐crystal neutron diffraction analysis will determine the crystal structure of the material, typically including its unit cell and space group, the positions of the atomic nuclei and their mean‐square displacements, and relevant lattice site occupancies. Because the neutron possesses a magnetic moment, the magnetic structure of the material can be determined as well from the magnetic contribution to the Bragg intensities.
Instruments for single‐crystal diffraction (single‐crystal diffractometers or SCDs) are generally available among the facilities at the major neutron‐scattering centers. Beam time on many of these instruments is available through a proposal mechanism. A listing of neutron SCD instruments and their corresponding facility contacts are given single‐crystal neutron diffraction and provides examples to illustrate the range of materials that can be studied.
Acetylenic Polymers, Substituted
Authors: Nomura Ryoji , Masuda Toshio 
Published: October 2003

AbstractThe tremendous development in the chemistry of substituted polyacetylenes, which has been made after the mid‐1980s, is surveyed. Focus is placed on the polymerization reaction of substituted acetylenes with various transition metal catalysts, on the precision synthesis of substituted acetylenes, and on the production of functional substituted acetylenes.
Acoustic Properties
Authors: Jarzynski Jacek , Balizer Edward , Fedderly Jeffry J. , Lee Gilbert 
Published: October 2003

Abstract
This article covers the use of acoustics as a molecular probe of polymer structure and describes various acoustic applications of polymers. Sound speed and sound absorption measurements in polymers are useful both as a probe of the molecular structure of polymers and as a source of engineering design properties. Enough theory and experimental details are given to make the presentation understandable, but the emphasis is on the experimental results for polymers. Most of the presentation is for small‐amplitude waves in solid polymers. References to some specialized topics are given.
Acrylamide Polymers
Authors: Huang Sun‐Yi , Lipp David W. , Farinato Raymond S. 
Published: October 2003

AbstractThis article presents an up‐to‐date, broad overview of acrylamide polymers covering their physics, chemistry, synthesis, and technology. Acrylamide polymers constitute a major segment of the global water‐soluble polymers market. The physics and chemistry of acrylamide polymers and copolymers in both the solid and solution states are discussed. Chemical properties and synthetic methods for acrylamide polymerization, copolymerization, and polymer derivatization are thoroughly covered, as are commercial manufacturing processes. The principal applications of acrylamide polymers are discussed, and there is coverage of modern methods of polymer analysis as applied to these materials. Safety and economic issues are also considered.
Acrylic (and Methacrylic) Acid Polymers
Authors: Swift Graham 
Published: October 2003

AbstractAcrylic polymers are widely used because of their unique properties. This article selectively focuses on polymers that contain acrylic acid and/or methacrylic acid. Their content ranges from <5 wt% to 100 wt% for use in applications such as adhesives, coatings, water‐soluble specialties, and superabsorbent gels. Acidic monomer selection and use may be based on monomer properties and characteristics, but is frequently based only on cost and availability, and this generally tips the choice to acrylic acid. As described, many polymer applications require optimized compositions and molecular weights that are uniquely available only by one of several different polymerization processes such as solution, emulsion, and graft, so as to accomplish commercial viability.
Acrylonitrile and Acrylonitrile Polymers
Authors: Wu Michael M. 
Published: October 2003

AbstractAcrylonitrile is a versatile and reactive monomer that can be polymerized under a wide variety of conditions and copolymerized with an extensive range of other vinyl monomers because of its polar nature and reactivity. Because of the difficulty of melt processing the acrylonitrile homopolymer, acrylonitrile is usually copolymerized to achieve a desirable thermal stability, melt flow, and physical properties. Acrylonitrile‐containing polymers are used in the areas of textile fibers, carbon fiber percursors, adhesives, binders, antioxidants, medicines, dyes, electrical insulations, emulsifying agents, graphic arts materials, insecticides, leather, paper, plasticizers, soil‐modifying agents, solvents, surface coatings, textile treatments, viscosity modifiers, azeotropic distillations, artificial organs, lubricants, asphalt additives, water‐soluble polymers, hollow spheres, cross‐linking agents, and catalyst treatments. Styrene is the largest volume acrylonitrile comonomer for thermoplastic applications. Styrene–acrylonitrile (SAN) copolymers are inherently transparent plastics with high heat resistance and excellent gloss and chemical resistance. They are also characterized by good hardness, rigidity, dimensional stability, and load‐bearing strength. In general, the styrene component of SAN resins offers clarity, stiffness, and processibility, while the acrylonitrile provides chemical and heat resistance. Because of their inherent transparency, SAN copolymers are most frequently used in clear application. These optically clear materials can be readily processed by extrusion and injection molding, but they lack real impact resistance. SAN resins show considerable resistance to solvents and are insoluble in carbon tetrachloride, ethyl alcohol, gasoline, and hydrocarbon solvents. Polar solvents dissolve SAN. The properties of SAN are significantly altered by water absorption. Commercially, SAN is manufactured by three processes: emulsion, suspension, and continuous mass polymerization. More than 75% of the SAN resin produced is believed to be used captively for acrylonitrile–butadiene–styrene compounding and in the production of acrylonitrile–styrene–acrylate and acrylonitrile–EPDM–styrene weatherable copolymers. SAN resins appear to pose few health problems, and they have been approved by the FDA for direct food contact. Copolymers of acrylonitrile and methyl acrylate and terpolymers of acrylonitrile, styrene, and methyl methacrylate are used as barrier polymers. Acrylonitrile multipolymers containing indene; methyl methacrylate, and α‐methylstyrene are used as poly(vinyl chloride) modifiers for heat distortion temperature and processibility improvement.
Acrylonitrile–Butadiene–Styrene Polymers
Authors: Kulich D. M. , Gaggar S. K. , Lowry V. , Stepien R. 
Published: October 2003

AbstractAcrylonitrile–butadiene–styrene (ABS) polymers are composed of elastomer dispersed as a grafted particulate phase in a thermoplastic matrix of styrene and acrylonitrile copolymer (SAN). The presence of SAN grafted onto the elastomeric component, usually polybutadiene or a butadiene copolymer, compatabilizes the rubber with the SAN component. Property advantages provided by this graft terpolymer include excellent toughness, good dimensional stability, good processibility, and good chemical resistance. The system is structurally complex. This allows considerable versatility in the tailoring of properties to meet specific product requirements. Numerous grades of ABS are available, including alloys and specialty grades for high heat, flaming‐retardant, or static dissipative product requirements. Good chemical resistance combined with the relatively low water absorptivity (<1%) results in high resistance to staining agents. The three commercial processes for manufacturing ABS are emulsion, mass, and mass‐suspension. ABS can be processed by compression and injection molding, extrusion, calendering, and blow molding. Post‐processing operations include cold forming, painting, and adhesive bonding. As a “bridge” polymer between commodity plastics and higher performance engineering thermoplastics, ABS has become the largest selling engineering thermoplastic.
Adhesion
Authors: Gent A. N. , Hamed G. R. 
Published: October 2003

AbstractA review is given of factors affecting the adhesion of plastics and elastomers. Particular attention is paid to the various causes of adhesion (or lack of it) and to the interpretation of mechanical tests of the strength of bonded joints in terms of a characteristic fracture energy. Several model experiments are described that allow general conclusions to be drawn of the roles of chemical interlinking, molecular interdiffusion, and energy dissipation within the bulk of a deformable adherend on the measured strength of adhesion.
Adsorption
Authors: Rao Ashwin , Dhinojwala Ali 
Published: October 2003

Abstract
Polymer adsorption finds widespread applications in the stabilization of colloids, food processing, paints, lubrication, and surface modification. In the past two decades there have been numerous studies aimed at improving our understanding of this important phenomenon. This article reviews the instrumental and theoretical advances made in this area and presents important experimental results concerning adsorbed polymers.
Aging, Physical
Authors: Simon Sindee L. 
Published: October 2003

Abstract
Physical aging is an important phenomenon that occurs in all glass‐forming materials, including polymeric glass‐formers. In this article, the manifestations of physical aging and structural recovery are described, including volume recovery, enthalpy recovery, evolution of viscoelastic properties, and the effects of physical aging on failure. Controversies in the field are discussed, including rejuvenation, the temperature dependence of the relaxation time at equilibrium density, and the relative time scales for relaxation of different properties, as well as modeling of structural recovery.
Amino Resins
Authors: Williams Laurence L. 
Published: October 2003

AbstractAmino resins are thermosetting polymers made by combining an aldehyde with a compound containing an amino (NH2) group. Urea–formaldehyde accounts for over 80% of amino resins; melamine–formaldehyde accounts for most of the rest. The principal attractions of amino resins and plastics are water solubility before curing, colorlessness, excellent solvent resistance, outstanding hardness and abrasion resistance, and good heat resistance. Amino resins provide a wide variety of useful products. Adhesives, the largest single market, are used to make plywood, chipboard, and sawdust board. Other types are used to make laminated wood beams, parquet flooring, and for furniture assembly. Aminoplasts and other thermosetting plastics are molded by an automatic injection‐molding process similar to that used for thermoplastics. The process is best applied to relatively small moldings. The great advantage of injection molding is that it eliminates manual labor costs, thereby allowing amino resins to better compete with thermoplastics. The future for amino resins and plastics seems secure. New developments will probably be in the areas of highly specialized materials for treating textiles, paper, etc, and for use with other resins in the formulation of surface coatings. Most amino resins are based on the reaction of formaldehyde with urea or melamine. The first step in the formation of resins and plastics from formaldehyde and amino compounds is the addition of formaldehyde to introduce the hydroxymethyl group, known as methylolation or hydroxymethylation. The second step is a condensation reaction that involves the linking together of monomer units with the liberation of water to form a dimer, a polymer chain, or a vast network, usually referred to as methylene bridge formation, polymerization, resinification, or simply cure. Precise control of the course, speed, and extent of the reaction is essential for successful manufacture. Amino resins are usually made by a batch process. Both urea– and melamine–formaldehyde resins are of low toxicity. Melamine–formaldehyde resins may be used in paper which contacts aqueous and fatty foods. However, some mills are looking for alternatives.
Amorphous Polymers
Authors: Ngai K. L. , Floudas G. , Plazek D. J. , Rizos A. K. 
Published: October 2003

AbstractStatic and dynamic properties of amorphous polymers are reviewed, with emphasis on experimental data. Various experimental techniques commonly used to probe these properties are described and their individual merits are made clear. The challenging problems that still remain to be solved for a satisfactory understanding of the dynamic properties of amorphous polymers are discussed.
Anionic Polymerization
Authors: Quirk Roderic P. 
Published: October 2003

AbstractThis article presents the fundamental principles of living anionic polymerization, including polymerizable monomers, kinetics and mechanism, stereochemistry, and copolymerization. The importance of anionic polymerization for preparation of model polymers with well‐defined structures and low degrees of compositional heterogeneity is illustrated with respect to molecular weight, molecular weight distribution, copolymer composition and comonomer distribution, stereochemistry, chain‐end functionality, and molecular architecture. Practical aspects of anionic polymerization are considered such as polymerizable monomers, solvents, and initiators. General kinetics, mechanisms, and stereochemistries of anionic polymerizations of styrenes, dienes, acrylates and methacrylates, vinylpyridines, epoxides, thiiranes, lactones, cyclic carbonates, and siloxanes are discussed. Effects of aggregation of the initiator and of the chain‐end on the kinetics of alkyllithium‐initiated polymerizations of hydrocarbon monomers are detailed. Experimental conditions that can cause chain transfer and chain‐termination reactions are presented. Copolymerization behavior, monomer reactivity ratios, and copolymer microstructure for styrenes and dienes are detailed to understand the syntheses of tapered block copolymers and random copolymers.