bluuebunny/crossref_metadata_2025_split huggingface dataset:
Oxide Dilute Magnetic Semiconductors—Fact or Fiction?
Authors: Coey J.M.D. , Chambers S.A. 
Published: February 2011

AbstractMagnetism in oxides was thought to be well-understood in terms of localized magnetic moments and double-exchange or superexchange rules. This understanding was shaken by the publication of an article in 2001 stating that thin films of anatase TiO2 with only 7 at.% Co substitution had a Curie point in excess of 400 K [Matsumoto et al., Science291, 854 (2001)]. Room-temperature ferromagnetism had previously been predicted for p-type ZnO with 5 at.% Mn [Dietl et al., Science287, 1019 (2000)]. A flood of reports of thin films and nanoparticles of new oxide “dilute magnetic semiconductors” (DMSs) followed, and high-temperature ferromagnetism has been reported for other systems with no 3dcations. The expectation that these materials would find applications in spintronics motivated research in this area. Unfortunately, the data are plagued by instability and a lack of reproducibility. In many cases, the ferromagnetism can be explained by uncontrolled secondary phases; it is absent in well-crystallized films and bulk material. However, it appears that some form of high-temperature ferromagnetism can result from defects present in the oxide films [Coey, Curr. Opin. Solid State Mater. Sci.10, 83 (2007); Chambers, Surf. Sci. Rep.61, 345 (2006)], although they are not DMSs as originally envisaged.
Environmental (S)TEM Studies of Gas–Liquid–Solid Interactions under Reaction Conditions
Authors: Gai Pratibha L. , Sharma Renu , Ross Frances M. 
Published: February 2011

AbstractWe review the development of time-resolved, high-resolution environmental scanning/ transmission electron microscopy [E(S)TEM] for directly probing dynamic gas–solid, liquid–solid, and gas–liquid–solid interactions at the atomic level. Unlike a regular TEM, such a microscope allows us to use high gas pressures (up to 40 mbars) in the sample region. The unique information available from experiments performed using E(S)TEM has enabled visualization of the dynamic nature of nanostructures during reactions. Such information can be directly applied to the development of advanced nanomaterials such as carbon nanotubes, silicon nanowires and processes, including the design of novel routes to polymers synthesis, and has aided in the identification of important phenomena during catalysis, chemical vapor deposition, and electrochemical deposition.
In Situ High-Resolution Transmission Electron Microscopy in the Study of Nanomaterials and Properties
Authors: Howe James M. , Mori Hirotaro , Wang Zhong Lin 
Published: February 2011

AbstractThis article introduces the use of in situ high-resolution transmission electron microscopy (HRTEM) techniques for the study and development of nanomaterials and their properties. Specifically, it shows how in situ HRTEM (and TEM) can be used to understand diverse phenomena at the nanoscale, such as the behavior of alloy phase formation in isolated nanometer-sized particles, the mechanical and transport properties of carbon nanotubes and nanowires, and the dynamic behavior of interphase boundaries at the atomic level. Current limitations and future potential advances in in situ HRTEM of nanomaterials are also discussed.
Observing Interfacial Sliding Processes in Solid–Solid Contacts
Authors: Wahl Kathryn J. , Sawyer W. Gregory 
Published: February 2011

AbstractDirectly seeing into a moving contact is a powerful approach to understanding how solid lubricants develop low-friction, long-lived interfaces. In this article, we present optical microscopy and spectroscopy approaches that can be integrated with friction monitoring instrumentation to provide real-time, in situ evaluation of solid lubrication phenomena. Importantly, these tools allow direct correlation of common tribological events (such as variations in friction and wear) with the responsible sliding-induced mechanical and chemical phenomena. We demonstrate the utility of in situ approaches with applications to a variety of thin-film solid lubricants.
Electroactive Polymer Actuators and Sensors
Authors: Bar-Cohen Yoseph , Zhang Qiming 
Published: February 2011

AbstractPolymers are highly attractive for their inherent properties of mechanical flexibility, light weight, and easy processing. In addition, some polymers exhibit large property changes in response to electrical stimulation, much beyond what is achievable by inorganic materials. This adds significant benefit to their potential applications.The focus of this issue of MRS Bulletin is on polymers that are electromechanically responsive, which are also known as electroactive polymers (EAPs). These polymers respond to electric field or current with strain and stress, and some of them also exhibit the reverse effect of converting mechanical motion to an electrical signal.There are many types of known polymers that respond electromechanically, and they can be divided according to their activation mechanism into field-activated and ionic EAPs. The articles in this issue cover the key material types used in these two groups, review the mechanisms that drive them, and provide examples of applications and current challenges. Recent advances in the development of these materials have led to improvement in the induced strain and force and the further application of EAPs as actuators for mimicking biologic systems and sensors. As described in this issue, the use of these actuators is enabling exciting applications that would be considered impossible otherwise.
Field-Activated Electroactive Polymers
Authors: Cheng Zhongyang , Zhang Qiming 
Published: February 2011

AbstractField-activated electroactive polymers (FEAPs) are a class of electroactive polymers that are insulating and exhibit coulombic interaction with and dipole formation in response to external electric signals. There are many polarization mechanisms in insulating polymers, from the molecular to the mesoscopic and even the macroscopic level, which couple strongly with mechanical deformation and can be used to create polymer actuators and sensors. FEAPs feature fast response speed limited by the polymer dielectric and elastic relaxation time, a very large strain level (to more than 100% strain), high electromechanical efficiency, the ability to operate down to micro/nanoelectromechanical devices, and a highly reproducible strain response under electric fields. One challenge in FEAP actuators and electromechanical devices is reducing the operation voltage to below 100 V or even 10 V while achieving an electromechanical conversion efficiency comparable with that of inorganic electroactive materials.
Physical Principles of Ionic Polymer–Metal Composites as Electroactive Actuators and Sensors
Authors: Park Il-Seok , Jung Kwangmok , Kim Doyeon , Kim Sang-Mun , Kim Kwang J. 
Published: February 2011

AbstractThis article introduces and considers the fundamental understanding of ionic polymer–metal composites (IPMCs) functioning as electroactive actuators and sensors. IPMCs consist of ion-exchange polymers acting as base materials and metal layers functioning as electrodes. The actuation and sensing abilities of IPMCs are dependent upon the components of ion-exchange polymers (ionic groups and cations) and electrode materials. In order to improve the bending and sensing performance of the IPMCs, an integral, two-step electroplating technique and a requisite dispersion agent are used during fabrication. Electroding materials also play a key role in determining the properties of IPMCs, and numerous methods in electroding have been tried, making use of various metals, carbon nanotubes, and composites. So far, IPMCs have been adapted as robotic actuators, artificial muscles, and electrical sensors. In the future, it is expected that IPMCs will broadly spread their roles from small-sized biomedical devices to large-scale actuators for aerospace as well as many industrial applications.
The Global Energy Landscape and Materials Innovation
Authors: Arunachalam V.S. , Fleischer E.L. 
Published: February 2011

AbstractAvailability of affordable energy has enabled spectacular growth of industrialization and human development in all parts of the world. With growth now accelerating in developing countries, demands on energy sources and infrastructure are being stretched to new limits. Additional energy issues include the push for renewable resources with reduced greenhouse gas emissions and energy security affected by the uneven distribution of energy resources around the globe. Together, these issues present a field of opportunity for innovations to address energy challenges throughout the world and all along the energy flow. These energy challenges form the backdrop for this special expanded issue of MRS Bulletin on Harnessing Materials for Energy. This article introduces the global landscape of materials issues associated with energy. It examines the complex web of energy availability, production, storage, transmission, distribution, use, and efficiency. It focuses on the materials challenges that lie at the core of these areas and discusses how revolutionary concepts can address them. Cross-cutting topics are introduced and interrelationships between topics explored. Article topics are set in the context of the grand energy challenges that face the world into the middle of this century.
The Economics of Energy Options
Authors: Lave Lester B. 
Published: February 2011

AbstractIncreasing demand for energy, diminishing stocks of oil and natural gas, and the public's desire to enhance environmental quality, particularly by reducing greenhouse gas emissions, all point to the need for improved materials. For example, generating electricity from the most abundant fossil fuel, coal, efficiently and with no environmental damage, presents notable challenges to develop higher performance materials. Technologies exist to transform one fossil fuel to other uses, such as coal to a gas or liquid. New materials that increase the efficiency of the transformation and lower its cost would provide valuable flexibility. Materials should be evaluated in terms of their entire life-cycle in order to discern which will make the greatest contribution. Because society has many pressing needs, both commercial value and contribution to fundamental materials science should guide priorities in materials research.
Materials Challenges in Advanced Coal Conversion Technologies
Authors: Powell Cynthia A. , Morreale Bryan D. 
Published: February 2011

AbstractCoal is a critical component in the international energy portfolio, used extensively for electricity generation. Coal is also readily converted to liquid fuels and/or hydrogen for the transportation industry. However, energy extracted from coal comes at a large environmental price: coal combustion can produce large quantities of ash and CO2, as well as other pollutants. Advanced technologies can increase the efficiencies and decrease the emissions associated with burning coal and provide an opportunity for CO2 capture and sequestration. However, these advanced technologies increase the severity of plant operating conditions and thus require improved materials that can stand up to the harsh operating environments. The materials challenges offered by advanced coal conversion technologies must be solved in order to make burning coal an economically and environmentally sound choice for producing energy.
Challenges in Materials Research for Sustainable Nuclear Energy
Authors: Raj Baldev , Vijayalakshmi M. , Rao P.R. Vasudeva , Rao K.B.S. 
Published: February 2011

AbstractGlobal energy demand is expected to increase steeply, creating an urgent need to evolve a judicious global energy policy, exploiting the potential of all available energy resources, including nuclear energy. With increasing awareness of environmental issues, nuclear energy is expected to play an important role on the energy scenario in the coming decades. The immediate thrust in the science and technology of nuclear materials is to realize a robust reactor technology with associated fuel cycle and ensure the cost competitiveness of nuclear power and to extend the service life of reactors to 100 years. Accordingly, the present-generation materials need to be modified to meet the demands of prolonged exposure to irradiation and extended service life for the reactor. Emerging nuclear systems incorporate features to ensure environmental friendliness, effective waste management, enhanced safety, and proliferation resistance and require development of high-temperature materials and the associated technologies. Fusion, on a longer horizon of about fve decades, also requires the development of a new spectrum of materials. The development of next-generation materials technology is expected to occur in short times and is likely to be further accelerated by strong international collaborations.
Advancing Materials and Technologies for Water Purification
Authors: Shannon Mark A. , Semiat Raphael 
Published: February 2011

AbstractWorldwide, 1.2 billion people lack access to sufficient amounts of clean water, and 2.6 billion lack adequate sanitation. Also, industry relies on large quantities of water during manufacturing, which is then returned to the environment. Having adequate water supplies, and removing pathogens, chemicals, and other contaminants with high throughput at a low cost is a growing challenge around the world. This issue of MRS Bulletin examines how materials research, through the development of membranes, catalysts, nanoparticles, and other materials, is addressing these needs.
Materials Challenges Facing Electrical Energy Storage
Authors: Whittingham M. Stanley 
Published: February 2011

AbstractDuring the past two decades, the demand for the storage of electrical energy has mushroomed both for portable applications and for static applications. As storage and power demands have increased predominantly in the form of batteries, the system has evolved. However, the present electrochemical systems are too costly to penetrate major new markets, still higher performance is required, and environmentally acceptable materials are preferred. These limitations can be overcome only by major advances in new materials whose constituent elements must be available in large quantities in nature; nanomaterials appear to have a key role to play. New cathode materials with higher storage capacity are needed, as well as safer and lower cost anodes and stable electrolyte systems. Flywheels and pumped hydropower also have niche roles to play.
Environmental Degradation of Materials in Advanced Reactors
Authors: Cabet C. , Jang J. , Konys J. , Tortorelli P. F. 
Published: February 2011

AbstractAdvanced fission-based reactors challenge our ability to fully understand environment–materials reactions in terms of fundamental stability and kinetics, including the influences of composition, microstructure, and system design, and to predict associated long-term performance. This article briefly describes corrosion reactions and the processes by which such are managed for several elevated-temperature environments associated with advanced reactor concepts: helium, molten Pb–Bi, fluorides, and supercritical water. For most of the subject environments, corrosion resistance critically depends on the ability to form and maintain protective surface layers. Effects of corrosion on mechanical behavior can be from thermally and chemically induced changes in microstructures or from environmental effects on cracking susceptibility. In most cases, the simultaneous effects of chemical reactivity and radiation have not been fully addressed, nor has much attention been paid to newly emerging alloy compositions or the effects of substantially increased operating temperatures.
Fuels for Advanced Nuclear Energy Systems
Authors: Petti D. , Crawford D. , Chauvin N. 
Published: February 2011

AbstractFuels for advanced nuclear reactors differ from conventional light water reactor fuels and also vary widely because of the specific architectures and intended missions of the reactor systems proposed to deploy them. Functional requirements of all fuel designs for advanced nuclear energy systems include (1) retention of fission products and fuel nuclides, (2) dimensional stability, and (3) maintenance of a geometry that can be cooled. In all cases, anticipated fuel performance is the limiting factor in reactor system design, and cumulative effects of increased utilization and increased exposure to inservice environments degrade fuel performance. In this article, the current status of each fuel system is reviewed, and technical challenges confronting the implementation of each fuel in the context of the entire advanced reactor fuel cycle (fabrication, reactor performance, recycle) are discussed.
Nanopolymeric Therapeutics
Authors: Tong Rong , Christian David A. , Tang Li , Cabral Horacio , Baker James R. , Kataoka Kazunori , Discher Dennis E. , Cheng Jianjun 
Published: February 2011

AbstractPolymers have been extensively utilized in the design of nanometer-sized delivery vehicles of chemotherapeutics for clinical cancer therapy. Polymeric nanoparticulate delivery vehicles, with chemotherapeutics being either conjugated or encapsulated, have been developed into a variety of different architectures, including polymer-drug conjugates with linear or branched polymers, micelles, and polymersomes. This review describes the progress that has been made in the field of polymeric nanomedicine that brings the science closer to clinical realization of nanopolymeric therapeutics for its application in cancer treatment.
Magnetic Nanoparticles for Early Detection of Cancer by Magnetic Resonance Imaging
Authors: Lin Wenbin , Hyeon Taeghwan , Lanza Gregory M. , Zhang Miqin , Meade Thomas J. 
Published: February 2011

AbstractThis article provides a brief overview of recent progress in the synthesis and functionalization of magnetic nanoparticles and their applications in the early detection of malignant tumors by magnetic resonance imaging (MRI). The intrinsic low sensitivity of MRI necessitates the use of large quantities of exogenous contrast agents in many imaging studies. Magnetic nanoparticles have recently emerged as highly efficient MRI contrast agents because these nanometer-scale materials can carry high payloads while maintaining the ability to move through physiological systems. Superparamagnetic ferrite nanoparticles (such as iron oxide) provide excellent negative contrast enhancement. Recent refinement of synthetic methodologies has led to ferrite nanoparticles with narrow size distributions and high crystallinity. Target-specific tumor imaging becomes possible through functionalization of ferrite nanoparticles with targeting agents to allow for site-specific accumulation. Nanoparticulate contrast agents capable of positive contrast enhancement have recently been developed in order to overcome the drawbacks of negative contrast enhancement afforded by ferrite nanoparticles. These newly developed magnetic nanoparticles have the potential to enable physicians to diagnose cancer at the earliest stage possible and thus can have an enormous impact on more effective cancer treatment.
Cantilever Sensors: Nanomechanical Tools for Diagnostics
Authors: Datar Ram , Kim Seonghwan , Jeon Sangmin , Hesketh Peter , Manalis Scott , Boisen Anja , Thundat Thomas 
Published: February 2011

AbstractCantilever sensors have attracted considerable attention over the last decade because of their potential as a highly sensitive sensor platform for high throughput and multiplexed detection of proteins and nucleic acids. A micromachined cantilever platform integrates nanoscale science and microfabrication technology for the label-free detection of biological molecules, allowing miniaturization. Molecular adsorption, when restricted to a single side of a deformable cantilever beam, results in measurable bending of the cantilever. This nanoscale deflection is caused by a variation in the cantilever surface stress due to biomolecular interactions and can be measured by optical or electrical means, thereby reporting on the presence of biomolecules. Biological specificity in detection is typically achieved by immobilizing selective receptors or probe molecules on one side of the cantilever using surface functionalization processes. When target molecules are injected into the fluid bathing the cantilever, the cantilever bends as a function of the number of molecules bound to the probe molecules on its surface. Mass-produced, miniature silicon and silicon nitride microcantilever arrays offer a clear path to the development of miniature sensors with unprecedented sensitivity for biodetection applications, such as toxin detection, DNA hybridization, and selective detection of pathogens through immunological techniques. This article discusses applications of cantilever sensors in cancer diagnosis.
Nanoscience and Nanotechnology: The Key to New Studies in Areas of Science Outside of Nanoscience and Nanotechnology
Authors: Gleiter Herbert 
Published: February 2011

AbstractIn recent years, a new branch of nanoscience/nanotechnology seems to be emerging. This branch is characterized by the application of preparation methods and/or the diagnostic tools developed in nanoscience/nanotechnology in order to perform either new, decisive experiments or to open the way to novel applications in areas of science that were originally not related to nanoscience/nanotechnology, such as cancer research or quantum physics. In order to highlight the diversity of this new branch, we shall discuss the following four areas in which methods of nanoscience/nanotechnology are applied to other areas of science: (1) cancer therapy, (2) cellular labeling, (3) the synthesis of solid materials with tunable atomic structures, and (4) the new opportunities provided by nanoscience/nanotechnology to probe the limits of quantum physics, one of the classical problems of physics.
Surface Defects and Passivation of Ge and III–V Interfaces
Authors: Houssa Michel , Chagarov Evgueni , Kummel Andrew 
Published: February 2011

AbstractThe need for high-κ gate dielectrics and metal gates in advanced integrated circuits has reopened the door to Ge and III–V compounds as potential replacements for silicon channels, offering the possibility to further increase the performances of complementary metal oxide semiconductor (CMOS) circuits, as well as adding new functionalities. Yet, a fundamental issue related to high-mobility channels in CMOS circuits is the electrical passivation of their interfaces (i.e., achieving a low density of interface defects) approaching state-of-the-art Si-based devices. Here we discuss promising approaches for the passivation of Ge and III–V compounds and highlight insights obtained by combining experimental characterization techniques with first-principles simulations.
Source and Drain Contacts for Germanium and III–V FETs for Digital Logic
Authors: Dimoulas Athanasios , Toriumi Akira , Mohney Suzanne E. 
Published: February 2011

AbstractThe scaling of transistors to smaller dimensions and the exploration of devices with III–V and Ge channels for digital logic places serious demands on the ohmic contacts used in these devices. Contacts with extremely low specific contact resistances are required to take full advantage of the performance promised by alternative semiconductor materials. In addition, device processes and contact morphologies must be compatible with the geometry and feature sizes of the transistors. In this article, we begin by reviewing what is known about contacts to Ge, InGaAs, InAs, and InSb, including the role of Fermi level pinning on the Schottky barrier that is often formed at the metal/semiconductor interface and common strategies for forming ohmic contacts. Then we turn our attention to the additional challenges faced when preparing ohmic contacts for the many types of field-effect transistors now under development for Ge and III–V complementary field-effect transistor technology.