bluuebunny/crossref_metadata_2025_split huggingface dataset:
YBCO-Coated Conductors Manufactured by High-Rate Pulsed Laser Deposition
Authors: Usoskin Alexander , Freyhardt Herbert C. 
Published: February 2011

AbstractHigh-temperature superconductors of the second generation—coated conductors—are based on an architecture of YBCO films deposited on a well-textured substrate tape. The deposition technique used in the processing of YBCO films is responsible not only for both the resulting critical currents in the conductors and the cost efficiency of the employed production route, but also for the ultimate viability of the chosen technology. This article describes an advanced deposition method for YBCO films using high-rate pulsed laser deposition (HR-PLD).An elaborate variable azimuth ablation allows target roughening to be considerably reduced in the course of continuous deposition, and as a result, the integral deposition speed and speed stability can be increased to technologically interesting high values.Well-selected process parameters have been demonstrated to yield high currents of up to 480A/cm-width in short tapes and 360A/cm-width in 6-m-long tapes.Together with quasi-equilibrium heating, the HR-PLD method allows the processing of long-length YBCO-coated conductors and offers a cost-efficient route for their production on an industrial scale.
The Pursuit of the Small: From Grain-Boundary Cavities to Nanocrystalline Metals
Authors: Weertman Julia R. 
Published: February 2011

AbstractThe following article is based on the Von Hippel Award presentation given by Julia Weertman of Northwestern University on December 3, 2003, at the Materials Research Society Fall Meeting in Boston.Weertman received the award for “her lifelong exceptional contributions to understanding the basic deformation processes and failure mechanisms in a wide class of materials, from nanocrystalline metals to high-temperature structural alloys, and for her inspiring role as an educator in materials science.” It has been said that “the best things come in small packages,” and that is certainly in Weertman's mind in this presentation.She has spent much of her career “in pursuit of the small.” In this article, she first looks back at her experiences studying grain-boundary cavities and life in the spaces between grains.She then fast-forwards to modern work on nanocrystalline mechanical behavior, confirming that such nanocrystalline materials are indeed strong, but also brittle.Some of her experiences in studying these phenomena are also described.
Unusual Phenomena in Exchange-Biased Nanostructures
Authors: Schuller Ivan K. 
Published: February 2011

AbstractThe following article is an edited transcript based on the MRS Medalist presentation given by Ivan K.Schuller of the University of California, San Diego, on December 3, 2003, at the Materials Research Society Fall Meeting in Boston.Schuller received the MRS Medal for “his innovative studies of exchange bias in magnetic heterostructures and nanostructures.” Magnetic nanostructures have received increasing attention in recent years, motivated by the interesting phenomena that are apparent when physical size becomes comparable with relevant magnetic length scales.In addition, a number of important potential applications in the sensors and storage industries have emerged. When magnetic nanostructures are in contact with dissimilar magnetic materials, and because their magnetic fields extend considerably outside the physical structure, they are very susceptible to interaction with the surrounding environment.A particularly interesting situation is a ferromagnetic nanostructure in contact with an anti-ferromagnetic substrate.In this “exchange-biased” configuration, a variety of unusual phenomena arise:The reversal mode of the ferromagnet changes considerably, the superparamagnetic transition temperature is affected, and there is a noticeable change in the microscopic spin configuration.A series of experiments will be described involving these phenomena in nanostructured ferromagnets prepared by electron-beam lithography and self-assembly.
Electronic Olfactory Systems Based on Metal Oxide Semiconductor Sensor Arrays
Authors: Pardo Matteo , Sberveglieri Giorgio 
Published: February 2011

AbstractIn this article, we present the Pico electronic nose, an artificial olfactory system based on thin-film semiconductor sensors, and two applications: food-quality control (coffee analysis) and environmental monitoring (odors at a landfill site). For both applications, the electronic nose data correlated with that of panels of trained judges. For the coffee, a global index (called the hedonic index) characterizing the sensorial appeal could be predicted with the electronic nose, and for the landfill site, the intensity of odors could be quantified. In this article, we stress the importance of stable and sensitive sensors, such as metal oxide thin films produced by sputtering, and of multivariate data analysis for extracting knowledge (e.g., gaining selectivity) from the data.
Classification of Ear, Nose, and Throat Bacteria Using a Neural-Network-Based Electronic Nose
Authors: Dutta Ritaban , Gardner Julian W. , Hines Evor L. 
Published: February 2011

AbstractThis article describes the use of an electronic nose (the Cyranose 320) to sense and identify three species of bacteria responsible for ear, nose, and throat (ENT) infections. Gathered data were a complex mixture of different chemical compounds. An innovative approach for classifying the bacteria data was investigated by using a combination of several clustering algorithms. The best results suggest that the three classes of bacteria examined can be predicted with up to 98% accuracy, allowing more precise diagnosis of ENT infection in patients. This type of bacteria data analysis and feature extraction is difficult, but it can be concluded that combined use of the analysis methods described here can solve the feature extraction problem with very complex data and enhance the performance of electronic noses.
Polymer–Carbon Black Composite Sensors in an Electronic Nose for Air-Quality Monitoring
Authors: Ryan M.A. , Shevade A.V. , Zhou H. , Homer M.L. 
Published: February 2011

AbstractAn electronic nose that uses an array of 32 polymer–carbon black composite sensors has been developed, trained, and tested. By selecting a variety of chemical functionalities in the polymers used to make sensors, it is possible to construct an array capable of identifying and quantifying a broad range of target compounds, such as alcohols and aromatics, and distinguishing isomers and enantiomers (mirror-image isomers). A model of the interaction between target molecules and the polymer–carbon black composite sensors is under development to aid in selecting the array members and to enable identification of compounds with responses not stored in the analysis library.
Organic Thin-Film Memory
Authors: Yang Yang , Ma Liping , Wu Jianhua 
Published: February 2011

AbstractRecently, organic nonvolatile memory devices have attracted considerable attention due to their low cost and high performance. This article reviews recent developments in organic nonvolatile memory and describes in detail an organic electrical bistable device (OBD) that has potential for applications. The OBD consists of a tri-layer of organics/metal nanoclusters/organics sandwiched between top and bottom electrodes. A sufficiently high applied bias causes the metal nanoparticle layer to become polarized, resulting in charge storage near the two metal/organic interfaces. This stored charge lowers the resistance of the device and leads to an electrical switching behavior. The ON and OFF states of an OBD differ in their conductivity by several orders of magnitude and show remarkable bistability—once either state is reached, the device tends to remain in that state for a prolonged period of time. More important, the conductivity states of an OBD can be precisely controlled by the application of a positive voltage pulse (to write) or a negative voltage pulse (to erase). Device performance tests show that the OBD is a promising candidate for high-density, low-cost electrically addressable data storage applications.
Molecular Memories Based on a CMOS Platform
Authors: Kuhr Werner G. , Gallo Antonio R. , Manning Robert W. , Rhodine Craig W. 
Published: February 2011

AbstractHybrid complementary metal oxide semiconductor (CMOS)/molecular memory devices are based on a dynamic random-access memory (DRAM) architecture, are fast, have high density, and exhibit low power consumption. These devices use a well-characterized charge storage mechanism to store information based on the intrinsic properties of molecules attached to a CMOS platform. The molecules are designed in a rational way to have known electrical properties and can be incorporated into CMOS devices with only minor modification of existing fabrication methods. Each memory element contains a monolayer of molecules (typically 100,000–1,000,000) to store charge; this process yields a structure that has many times the charge density of a typical DRAM capacitor, obviating the necessity for a trench or stacked capacitor geometry. The magnitude of voltage required to remove each electron is quantized (typically a few hundred millivolts per state), making it much easier to put molecules in a known state and to detect that state with low-power operation. Existing devices have charge retention times that are >1000 times that of semiconductors, and nonvolatile strategies based on simple modifications of existing systems are possible. All of these devices are ultimately scalable to molecular dimensions and will enable the production of memory products as small as state-of-the-art lithography will allow.
Nonvolatile Silicon Memory at the Nanoscale
Authors: Silva Helena , Kim Moon Kyung , Avci Uygar , Kumar Arvind , Tiwari Sandip 
Published: February 2011

AbstractThe key challenges for memories that operate at the nanoscale and that are compatible with mainstream semiconductor processing are in achieving the performance characteristics that make the integration of hundreds of millions or more of such devices feasible. The concept of harnessing a single electron or just a few electrons for memory storage is very appealing, but among the issues to address are the increased variance, smaller signal, and numerous other consequences of the reduced statistics resulting from reduced number of carriers employed. Coupling a few electrons to a transistor channel provides a structure with the power gain and the necessary current for fast memory-state detection as well as compatibility with mainstream processing. Several recent ideas, such as the use of nanocrystals and defects, and decoupling storage from the read process, provide paths to addressing the issues of power, speed, technology compatibility, and variability in these structures.We discuss several approaches to nanoscale nonvolatile silicon memory, their attributes, and the underlying materials issues, with a focus on finding the design compromises necessary to enable their manufacturability.
Solid–Liquid Interfaces: Molecular Structure, Thermodynamics, and Crystallization
Authors: Asta Mark , Spaepen Frans , Veen J. Friso van der 
Published: February 2011

AbstractMaterials phenomena ranging from the melting or freezing of ice to biomineralization in living organisms, to lubrication and the commercial casting of superalloys, are known to be critically influenced by molecular-scale structure and processes occurring at the interfaces between the crystalline solid and liquid phases. The properties of solid–liquid interfaces have long been a topic of intense interest in materials science, primarily because of their role in governing nucleation, growth, and morphological evolution in crystal growth from the melt or solutions.This issue of the MRS Bulletin provides an overview, highlighting new developments in experiment, theory, and modeling techniques that have led to substantial recent progress in the characterization of the molecular-level structural and thermodynamic properties of solid–liquid interfaces and their consequences for a variety of crystallization phenomena.
Step and Kink Dynamics in Inorganic and Protein Crystallization
Authors: Chernov A.A. , Yoreo J.J.De , Rashkovich L.N. , Vekilov P.G. 
Published: February 2011

AbstractRevived interest in crystal growth from solutions is driven by a variety of demands, including the need to develop an understanding of biomineralization processes in bones, teeth, and shells;and efforts to characterize large optically nonlinear crystals, perfect crystals of proteins, nucleic acids, and complexes such as viruses. Producing and purifying drugs, food, paint, fertilizers, and other polycrystalline materials in industry are other expanding areas that rely on crystal growth from solution. These general practical incentives have activated in-depth studies that revealed new phenomena and raised new fundamental questions: Are thermal fluctuations of steps on a crystal face always fast enough to assure the step propagation at the rate controlled just by molecular incorporation at kinks? Is the Gibbs–Thomson capillarity shift of thermodynamic equilibrium always applicable to evaluate the crystallization driving force of polygonized steps? Is it possible to eliminate the step bunching on a growing crystal face that compromises crystal homogeneity, or at least to mitigate it? In this overview, we will discuss experimental findings and provide state-of-the-art answers to these questions.
New Developments in Colloid Science
Authors: Weitz D.A. , Russel W.B. 
Published: February 2011

AbstractThis introductory article reviews the topics covered in this issue of MRS Bulletin on New Developments in Colloid Science. Colloidal particles have a long history of importance in a broad range of applications in technology and materials processing. They can be made from many different materials and suspended in a wide variety of solvents. The rheological properties of colloidal suspensions have traditionally been of primary concern in their technological applications, and our understanding of these properties continues to evolve. However, new uses of colloidal particles are also emerging. Because they can be produced to a precise size, colloidal particles are now also being used in novel ways as building blocks for engineering completely new materials, including high-precision filters, controlled-porosity substrates, and photonic devices. In addition, new methods are evolving to alter the shape of the particles and create controlled structures with nonspherical particles. New experimental techniques are allowing improved measurement and increased understanding of the structure, properties, and behavior of colloidal suspensions. Significant progress continues to be made, and the potential uses of colloidal particles continue to grow. This issue presents a snapshot summary of recent developments in this field.
Three-Dimensional Coherent X-Ray Diffraction Microscopy
Authors: Robinson Ian K. , Miao Jianwei 
Published: February 2011

AbstractX-rays have been widely used in the structural analysis of materials because of their significant penetration ability, at least on the length scale of the granularity of most materials. This allows, in principle, for fully three-dimensional characterization of the bulk properties of a material. One of the main advantages of x-ray diffraction over electron microscopy is that destructive sample preparation to create thin sections is often avoidable. A major disadvantage of x-ray diffraction with respect to electron microscopy is its inability to produce real-space images of the materials under investigation—there are simply no suitable lenses available. There has been significant progress in x-ray microscopy associated with the development of lenses, usually based on zone plates, Kirkpatrick–Baez mirrors, or compound refractive lenses. These technologies are far behind the development of electron optics, particularly for the large magnification ratios needed to attain high resolution. In this article, the authors report progress toward the development of an alternative general approach to imaging, the direct inversion of diffraction patterns by computation methods. By avoiding the use of an objective lens altogether, the technique is free from aberrations that limit the resolution, and it can be highly efficient with respect to radiation damage of the samples. It can take full advantage of the three-dimensional capability that comes from the x-ray penetration. The inversion step employs computational methods based on oversampling to obtain a general solution of the diffraction phase problem.
Carbon Nanotubes: Continued Innovations and Challenges
Authors: Dresselhaus M.S. , Dai H. 
Published: February 2011

AbstractThis article outlines the content of the April 2004 issue of MRS Bulletin on Advances in Carbon Nanotubes. Essentially, carbon nanotubes are self-assembling nanostructures constructed of sheets of hexagonal-shaped carbon atoms rolled up into cylinders. Carbon nanotubes have attracted a great deal of attention as model systems for nanoscience and for potential applications. The special interest in carbon nanotubes stems from their unique structure and properties: their very small size (down to ∼0.42 nm in diameter); the possibility for carbon nanotubes to be metallic or semiconducting, depending on their geometrical structure; their exceptional properties of ballistic transport; their extremely high thermal conductivity and high optical polarizability; and the possibilities of high structural perfection. Research in the carbon nanotube field has now advanced to the stage where a good understanding of the structure and many of the basic properties are in place, together with much appreciation of their interrelation. On the other hand, major gaps in basic knowledge remain, with the major obstacles confronting the carbon nanotube field being the lack of a detailed understanding of the nanotube growth mechanism and control of the synthesis process to produce nanotubes with a desired diameter and chirality. The brief review of the carbon nanotube field by leading experts in this issue comes at an opportune time. Many exciting results on the structural, electronic, optical, and transport properties of these tiny well-ordered structures have already been achieved, and the research is well enough developed to assess present progress and identify new research directions waiting to be explored.
Purification and Separation of Carbon Nanotubes
Authors: Haddon R.C. , Sippel J. , Rinzler A.G. , Papadimitrakopoulos F. 
Published: February 2011

AbstractThe problems posed by the synthesis and purification of single-walled carbon nanotubes (SWNTs) have inhibited progress in the field. In this article, we review the methods available for measuring the purity of SWNTs and the current status of processes designed to purify them.We emphasize the hierarchy of the purification steps that must be developed in order to obtain high-quality material suitable for the full range of advanced applications that are envisioned for the ultimate carbon nanofiber.We review two strategies for SWNT purification, the assessment of SWNT purity by use of near-IR spectroscopy and its application to the thermal oxidation of thin films of SWNTs, as well as recent advances in the separation of metallic and semiconducting SWNTs. While substantial progress has been made in the purification and separation of SWNTs, we note the need for quality control and quality assurance within the industry. Much work remains before pure SWNTs of specific lengths, diameters, and chirality can be made available for applications.
Electron Transport in Single-Walled Carbon Nanotubes
Authors: McEuen Paul L. , Park Ji-Yong 
Published: February 2011

AbstractSingle-walled carbon nanotubes (SWNTs) are emerging as an important new class of electronic materials. Both metallic and semiconducting SWNTs have electrical properties that rival or exceed the best metals or semiconductors known. In this article, we review recent transport and scanning probe experiments that investigate the electrical properties of SWNTs.We address the fundamental scattering mechanisms in SWNTs, both in linear response and at high bias.We also discuss the nature and properties of contacts to SWNTs. Finally, we discuss device performance issues and potential applications in electronics and sensing.
Carbon Nanotube Photophysics
Authors: Jorio A. , Saito R. , Hertel T. , Weisman R.B. , Dresselhaus G. , Dresselhaus M.S. 
Published: February 2011

AbstractIn single-walled carbon nanotubes (SWNTs), their electronic and vibrational structure as well as their charge-carrier dynamics are crucial for potential ultrasmall optical device applications. SWNT properties have now been obtained from optical absorption and time-resolved photoemission and, at the single-nanotube level, by resonance Raman scattering and photoluminescence studies. This article presents an overview of SWNT photophysics, discussing important findings for the characterization of carbon nanotube properties and directions for future research and potential applications. The unique optical properties observed in SWNTs are due to the one-dimensional confinement of electronic states, resulting in van Hove singularities in the nanotube density of states. Optical measurements of phonons, charge-carrier dynamics, and the electronic transition energy van Hove singularities are discussed.
Why Does Concrete Set?: The Nature of Cohesion Forces in Hardened Cement-Based Materials
Authors: Pellenq Roland J.-M. , Van Damme Henri 
Published: February 2011

AbstractUnlike other porous materials such as sandstone, brick, or porous glass, the interatomic bonding continuity of cement-based materials like concrete is far from obvious. When scrutinized at the micro- or nanoscopic level, the continuity of the ionic–covalent bonding in the solid phase is interrupted almost everywhere by water molecules or liquid water films. The same situation is found in set plaster.Yet, plaster and cementitious materials are able to withstand stresses of the same order of magnitude as rocks. Molecular simulation studies and direct-force measurements by atomic force microscopy provide strong arguments for predicting that short- and medium-range surface forces mediated by partially or totally hydrated calcium ions are the essential components of cement strength, with additional contributions from van der Waals and capillary forces. This provides a clue for understanding the nano- and mesostructure of cement-based materials and new levers for improving their properties.
Ultra-Durable Concretes: Structure at the Micro- and Nanoscale
Authors: Vernet Christian P. 
Published: February 2011

AbstractUltrahigh-performance concretes (UHPCs) are obtained by optimizing several technologies: minimizing the amount of water added, using superplasticizers and a wide particle size distribution, and packing the particles to improve fluidity with minimized water additions and to optimize load-carrying capacity. Fibers can be incorporated to increase ductility, leading to ultrahigh-performance fiber-reinforced concretes (UHPFRCs). Such enhanced concretes can approach the compressive strength of steel, with a remarkable improvement in durability. UHPCs offer new solutions for innovative construction, especially in aggressive environments.