bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polymer-Dispersed Liquid Crystals: Boojums at Work
Authors: Doane J. William 
Published: August 2016

The idea of dispersing micron-size birefringent particles in a polymer to selectively scatter light is not new. In the 1930s Land patented a light polarizing material in which small, oriented solid crystallites were suspended in a clear polymer. The polymer material was selected so that its refractive index matched one of the principal refractive indices of the crystallites while the other did not. The resuit was a light polarizer tha t would pass one component of polarized light but scatter the other component out of the beam path.This idea was substantially expanded by the introduction of liquid crystals as the birefringent material. The orientation of the particles (in this case droplets), and hence the refractive index match and the scattering, could be controlled by an electric field. Such a material could be used as a light shutter for either unpolarized or polarized light. In the mid-1970s this basic concept was applied by Hilsum, but having no way to disperse droplets of liquid crystals in a polymer, he did the opposite and put optically isotropic solid particles in the birefringent liquid crystal.Although Hilsum demonstrated the concept, no commercial device was produced, probably because the shutter contrast was limited. Since then several ways have been found to disperse droplets in a polymer: filling the pores of a microfilter; emulsifying the liquid crystal in a water soluble polymer; and using phase separation methods to create a dispersion of droplets in non-aqueous polymer materials.
Liquid Crystal Elastomers with Piezoelectric Properties
Authors: Meier Wolfgang , Finkelmann Heino 
Published: August 2016

During the last few years, liquid crystalline elastomers (LCEs) have been systematically produced by cross-linking liquid crystalline side-chain polymers. In these networks, a liquid crystalline molecule is fixed at each monomeric unit. LCEs exhibit a novel combination of properties. Due to liquid crystalline groups, they show anisotropic liquid crystalline properties similar to conventional liquid crystals (LCs); but due to the three-dimensional network-structure of the polymer chains, they show typical elastomer properties, such as rubber elasticity or shape stability. One exceptional property of this combination is demonstrated when a mechanical deformation to the LCE causes macroscopically uniform orientation of the long molecular axis of the LC units (the so-called “director”).This response of the LC-phase structure to an applied mechanical field is similar to the effect of electric or magnetic fields on low molecular weight liquid crystals (LMLC), as illustrated in Figure 1. Figure la shows an undeformed LCE. Because of the non-uniform orientation of the director, the sample scatters light strongly so the elastomer is translucent like frosted glass. On the other hand, applying a mechanical field the director becomes uniformly aligned and the sample is transparent (Figure 1b). Such a macroscopically ordered rubber exhibits optical properties very similar to single crystals. These propertie s of LCEs offer new prospects for technical application, e.g., in nonlinear and integrated optics.
Low-Density Microcellular Materials: Introduction
Authors: LeMay J.D. , Hopper R.W. , Hrubesh L.W. , Pekala R.W. 
Published: August 2016

This article is dedicated to a class of specialty materials that have come to be known as low-density microcellular materials, or LDMMs. LDMMs have been developed and studied over the last decade at several U.S. Department of Energy (DOE) National Laboratories. LDMMs are used in various high energy physics programs where they meet unusual and demanding specifications (see Table 1.1).To set the stage for introducing LDMMs, it is instructive to contrast them with more familiar cellular materials. Examples of commercially available low-density materials are plastic “blown cell” foams, such as polyurethane cushions and polystyrene coffee cups. Asymmetric membranes and filters, on the other hand, are representative of commercially available microcellular materials. The processes used to make these products generally are not suitable for making LDMMs, however, because they are limited by a tradeoff between density and cell size. That is, they yield low densities only at the expense of increased cell size, or small cell size at the expense of increased density. The challenge to DOE materials scientists, therefore, has been to develop new methods for making materials that simultaneously have low density and microcellular morphology, and also meet other application requirements (e.g., composition, homogeneity, size, and strength).LDMMs are used by the DOE laboratories because their low density and high homogeneity (implied from their microcellular morphology) make them ideal precursors or substrates for forming high-density gases or expanded plasmas.
From Concept to Commerce: The Challenge of Technology Transfer in Materials
Authors: Hench Larry L. 
Published: August 2016

Many millions of dollars are invested annually in materials science research and development in U.S. universities. Both the universities and the sponsors, either government or private industry, have enormous incentives for the R&D efforts to become commercial. For private industry a successful development means new or improved products or processes and ultimately more profits. For the government, successful materials development can lead to improved hardware or operations efficiency and lower costs. For a university the payoff can be more than economic.Ideally, successful commercial development leads to royalties paid to the universities in the form of the most precious of assets — Unrestricted or flexible income. Students and faculty can benefit from the additional income, both privately, depending on university policy, and through their departments. However, benefits can also accrue in the form of experience and knowledge gained while participating in the technology transfer process from university to corporation. Students who take part in such efforts gain invaluable experience in preparing and defending patent applications, designing and developing prototypes, and they are exposed to economic and legal issues that are seldom taught in the classroom. They become more valuable graduates. Taking part in a technology transfer case history is a far more effective form of learning than reading about it.These benefits to a university are offset by a number of potentially negative factors. The space, time, personnel, equipment, and deadline pressures involved in commercialization are often beyond the capabilities of a university program. However, these limitations may not be realized until the effort has begun, and it is costly to stop in midstream, as is discussed below.
Overcoats and Lubrication for Thin Film Disks
Authors: Homola A.M. , Mate C.M. , Street G.B. 
Published: August 2016

Metallic alloy thin film media and ever decreasing head-to-media spacing make severe demands on storage devices. Decreasing head-to-media separation is critical for high storage densities but it also leads to increased slider-disk interactions, which can cause slider and disk wear or even head crashes. Wear can also occur when drives start and stop when the slider contacts the disk at relatively high speeds. The reliability and durability of thin film disks, which provide much higher areal density than conventional oxide disks with particulate media, are achieved by the use of very thin overcoat materials and surface lubricants. This article summarizes the approaches taken in the industry to enhance the tribological performance of magnetic media, with special emphasis on the basic understanding of the processes occurring at the slider-disk interface.The continuous rise in the demand for storage capacity at a competitive price is the prime motivator of the changes we have seen in the data storage industry. It is clearly stimulating the present move away from particulate media, which has long dominated all fields of data storage, i.e., tape, rigid, and flexible disks, to the thin film storage media. Particulate storage devices use magnetic media formulated by dispersing magnetic particles, usually iron oxides, in an organic binder. In thin film storage devices, the storage medium is a continuous magnetic film, usually a cobalt alloy, made either by sputtering or by electroless plating.
Adhesion of Fine Particles at Solid/Solution Interfaces
Authors: Kallay Nikola 
Published: August 2016

The adhesion of particles at solid surfaces in liquid media has attracted the attention of scientists because of its various applications as well as the theoretical significance of the processes involved. Early studies were characterized either by poorly defined systems or limited by the properties of a few morphologically well-defined model colloids, such as latex dispersions. Consequently, results were either of semiquantitative nature or were related to some specific cases, which eluded general conclusions. New methods for preparing uniform particles of different compositions, shapes, and sizes make it possible to approach the problem in a more comprehensive manner. For example, to demonstrate difficulties caused by polydispersity, it is sufficient to mention that the electrostatic interaction energy between a plane surface and a particle is approximately proportional to the particle radius, yet the rate of deposition depends exponentially on the height of the energy barrier.In principle, static and dynamic approaches may be employed in the study of particle adhesion. The static method yields the force required to detach an adhered particle, while kinetic investigations of attachment and detachment give the rates of the respective processes. Both methods offer information on the stability of the system in terms of the bond strength of adhered solids. For small colloid particles, which are the subject of thermal random Brownian motion, the dynamic approach is more appropriate. This article emphasizes the kinetics of deposition and detachment of small colloid particles in liquid media.
Preparation and Characterization of Monodispersed Colloidal Particles
Authors: Sugimoto Tadao 
Published: August 2016

Recently the science and technology of fine particles have been greatly advanced to meet the urgent demands of modern industries for specific and sophisticated functions for various materials, including catalysts, sensors, electromagnetic devices, and photosensitive materials. Monodispersed colloidal Systems are invaluable for this purpose because the entire system's uniform physicochemical properties directly reflect the properties of each constituent particle. Procedures for modifying monodispersed particles have progressed remarkably in recent years so that specific characteristics can be achieved. This article focuses on the backgrounds of science and technology for controlling the properties of inorganic monodispersed particles and on new developments in this field.Colloidal particles are normally formed through a sequential process of nucleation and growth of the nuclei. To obtain a monodisperse System, the two stages must be strictly separated and nucleation avoided during the growth period. Since the steady concentration of monomers in the growth stage is determined by the balance between the rates of generation of monomers and their consumption by particle growth, the generation or introduction rate of monomers must be controlled so that it is low enough to keep the balanced monomer concentration below the critical supersaturation after the nucleation period. Typically, the initial concentrations of metal sait, pH, and temperature are adjusted to meet this requirement for the formation of monodispersed metal hydrous oxide particles by forced hydrolysis of metal ions.An artificial separation between nucleation and growth processes may be achieved by “seeding,” in which foreign particles are introduced into the solution of monomers below the critical supersaturation. One may also lower the pH in hydrolysis of metal ions, dilute with solvent, add chelating agents, or suddenly change the temperature just after limited nucleation. All these procedures could cause the monomer concentration above the critical supersaturation to plunge to a level below it.
Preparation and Properties of Well-Defined Magnetic Particles
Authors: Ozaki Masataka 
Published: August 2016

Magnetic particles are important not only in the technology, but also in the function of some biosystems. In addition, they are of great scientific interest in developing a better understanding of magnetic phenomena. Ever since magnetic recording media were first prepared, extensive efforts have been made to produce improved magnetic dispersions. The particle s for magnetic media must be of single domain, high saturation magnetization, and proper coercive force. However, the magnetic interactions between such particles are very strong, and stable dispersions are difficult to obtain. Originally, their use was limited to audio tapes, but presently they are employed in a variety of applications. Thus, small particles of different magnetic properties are constituents of magnetic fluids.In 1975, magnetic particles were identified in the bodies of some bacteria, which can navigate along geomagnetic fields. It is also believed that certain animais have the ability to detect a magnetic field due to the presence of magnetic particles in their cells.Techniques are being developed to introduce new functions to materials by incorporating magnetic particles. For example, magnetic particles that are encapsulated by nonmagnetic compounds (e.g. polymers) or particles are used for binding and separating enzymes from reactant mixtures. Efforts are under way to use magnetic particles in drug delivery Systems and for diagnosis.
Selected Refractory Advances in Steel-Handling Systems
Authors: Brezny B. , Vezza T.F. , Leitzel T.A. 
Published: August 2016

The iron and steel industry is constantly undergoing technological changes in improving its processes to produce the highest quality world-class steels. As a consequence, the refractories industry has been challenged to keep in lock-step with the iron and steel industry to enhance, not detract from these processes.Certain internal combinations have enabled these refractories changes. Three expositions can display the sophistication to which refractories have advanced, so this article will explore refractories for primary steelmaking, ladles, and slide-gate devices for continuous casting.The start-up of the first top-blown oxygen vessel at the Linz Works in Austria 37 years ago was a historical milestone in the evolution of steelmaking. At that time the open-hearth process was the dominant steelmaking technology in the world. Ten to 12 hours were required to produce one batch of steel in the open-hearth furnace, but only one hour is needed to refine the same amount of steel in a basic oxygen furnace (BOF). In a top-blown BOF all oxygen required for refining is introduced into the vessel through the oxygen lance inserted through the top of the vessel.Toward the end of the 1960s, bottom-blown processes, such as OBM and Q-BOP, became very important in oxygen steelmaking. In the bottom-blown process, oxygen and lime are blown into the steel batch through bottom tuyeres.
Refractories for Glass Making
Authors: Busby T.S. 
Published: August 2016

Glass melting has changed very little in general principles since the earliest times, still being produced in fireclay pots or crucibles—even up to the present day. In Europe, experiments to melt glasses in tank furnaces began about 1700 A.D., but this became an important form of glass manufacture after Siemens introduced the regenerative furnace in 1870. This design was the basis for the development of modern furnaces and there is still a considerable similarity to the original.Until the late 1920s the glass contact refractories used in tank furnaces were based on fireclay or sandstone blocks. About this time important changes began when sillimanite and fusion-cast mullite refractories became available. However, because of the higher cost of fusion-cast refractories the introduction of these materials was delayed and they did not come into general use for lining the glass melting tank until the late 1940s.The high performance of tank furnaces today is related to a number of factors such as improved furnace design and regeneration, but the most significant has been an improved melting rate brought about by the use of higher temperatures. This has only been achievable as a result of the improved quality of fusion-cast and other refractory materials, such as those used in the furnace superstructure and regenerators. Garstang showed that there has been a steady increase in melting temperatures in the container glass industry. In data going back to 1920, there has been an increase from about 1300°C to some 1590°C. Bondarev showed that the increase in production achieved by using higher temperatures reduces the specific consumption of fuel.
Cathodoluminescence Microscopy: A Valuable Technique for Studying Ceramic Materials
Authors: Hagni Richard D. , Karakus Musa 
Published: August 2016

Over the past 10 to 20 years, cathodo-luminescence microscopy (CLM) has become an important, standard technique for studying many geological materials, but its application to ceramic material has not been fully realized. CLM has been found to be especially valuable in determining original porosity in carbonate rocks, a feature that was extremely important in determining the ability of petroleum and related fluids to migrate through the rocks and concentrate in the favorable structures where petroleum is found today. CLM constitutes one of the most significant techniques employed in the exploration for petroleum, but the results of those investigations remain largely unpublished in company files. A number of investigations have discussed the application of cathodoluminescence (CL) to studies of porosity in carbonates.Other applications of CLM to geology involve metals exploration. Halos of red CL feldspar in the rocks around carbon-atite deposits, which may contain rare earths, copper, and other metals, contrast with feldspar crystals with blue or blue-green CL that are distal from the ore deposits. Dolomite associated with lead-zinc ores may exhibit growth zoning by CL that can be used to trace the path of the ore fluids for distances of 100 miles or more. The detection of host rock limestone alteration in the Tri-State zinc-lead district, potassic and argillic alteration at the Henderson molybdenite mine, and ore guides in other metallic deposits by CL was discussed by Hagni.
Diamond Growth at Low Pressures
Authors: Angus J.C. , Buck F.A. , Sunkara M. , Groth T.F. , Hayman C.C. , Gat R. 
Published: August 2016

Diamond synthesis has attracted attention ever since it was established in 1797 that diamond is a crystalline form of carbon. Initially, synthesis was attempted at high pressures because diamond is the densest carbon phase. As understanding of chemical thermodynamics developed through the 19th and 20th centuries, the pressure-temperature range of diamond stability was explored. These efforts culminated in the announcement in 1955 of a process for diamond synthesis with a molten transition metal solvent-catalyst at pressures where diamond is thermo-dynamically stable. Worldwide sales of synthetic diamond now approach 330 million carats (73 tons) with a market price of between $500 million to $1 billion.Over the past 40 years a parallel effort has been directed toward the growth of diamond at low pressures, where it is metastable. Although diamond was successfully produced, low-pressure synthesis was plagued by extremely low growth rates. Recent developments have led to much higher growth rates, creating great interest in the field. Polycrystalline diamond films can now be produced on a variety of substrates at linear growth rates of tens to hundreds of micrometers per hour. In addition, the recognition of an entirely new class of solids, the so-called “diamondlike” carbons and hydrocarbons has arisen from this work. This article will discuss both crystalline diamond grown at low pressure and the diamondlike phases.The interest in diamond is driven by its extreme properties, summarized in Table I. Diamond stands alone as the densest (number density), strongest (elastic modulus), and hardest known material.
Innovations in Testing Methodology for Fusion Reactor Materials Development
Authors: Lucas G.E. , Odette G.R. , Rowcliffe A. F. 
Published: August 2016

The successful development of fusion power critically depends on structural materials which can maintain their integrity and dimensional stability in an extremely hostile service environment involving high temperatures and heat fluxes, corrosive media, high stresses, and intense fluxes of neutrons. Neutron irradiation results in a variety of mechanical, physical, and chemical property changes that are collectively referred to as radiation effects. The primary sources of damage are neutron-induced atomic displacements and transmutation products.High-energy neutrons produce primary recoil atoms (PKAs) with energies ranging from less than 1 keV to more than 100 keV. The energetic PKAs create a cascade of additional displacements. About 10% of the displaced atoms survive cascade recombination as isolated vacancies and self-interstitials or small clusters of these defects. The mobile defects migrate to pre-existing sinks such as grain boundaries and dislocations, or cluster to form a variety of extended defects such as voids (vacancies) or faulted dislocation loops (interstitials).