bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nanotubes and the Pursuit of Applications
Authors: de Heer Walt A. 
Published: February 2011

AbstractA wide range of potential applications was suggested shortly after carbon nanotubes were discovered, including new super-strong materials, field-emission devices, hydrogen storage systems, novel electronic devices, and more. In this article, the actual advances in the technology of nanotubes over the last decade are examined. Particular attention is focused on current commercially viable applications and those with imminent commercial promise. The relatively large number of nanotube-related patents and nanotube-based startup companies stand in contrast to the relatively low output in commercial applications. The drive toward nanotube applications, in contrast to nanotube science, is investigated.
Photocatalysis of Cementitious Materials: Clean Buildings and Clean Air
Authors: Cassar Luigi 
Published: February 2011

AbstractWhile the primary function of concrete is structural, its pervasiveness in our society lends it to other functions and creates the need for it to maintain its integrity and aesthetic quality. Therefore, concrete with added functionality–for example, self-cleaning characteristics and the ability to remove pollutants–is desirable. Heterogeneous photocatalysis (e.g., gas–solid or liquid–solid catalytic processes caused by light irradiation) by semiconductor particles or coatings has now reached a high level of development and is a promising technology for the reduction of global environmental pollutants. Among the various semiconductor materials, TiO2 in the form of anatase has attracted wide interest, due to its strong oxidizing power under near-UV radiation, its chemical stability when exposed to acidic and basic compounds, its chemical inertness in the absence of UV light, and the absence of toxicity. TiO2 has proved very effective in the reduction of pollutants such as NOx, aromatics, ammonia, and aldehydes. Surprisingly, the use of TiO2 in combination with cementitious materials has shown a favorable synergistic effect in the reduction of pollutants. These new materials have already found relevant applications in self-cleaning building walls and in the reduction of urban pollutants.
Designing New Structural Materials Using Density Functional Theory: The Example of Gum MetalTM
Authors: Ikehata H. , Nagasako N. , Kuramoto S. , Saito T. 
Published: February 2011

AbstractAs an example of the application of density functional theory (DFT) to materials design, we describe our use of ab initio calculations based on DFT to develop a new structural material: Gum MetalTM, a novel, multifunctional titanium alloy with a low Young's modulus and high strength. We first carried out calculations on elastic constants in several Ti-X binary alloys to obtain the basic principles on which to determine the compositional limitations of an alloy with a low modulus. The elastic properties in the Ti-based binary alloys were successfully estimated by ab initio calculations, with the result implying absolute elastic softening at the valence electron number per atom, e/a, of 4.24. We also studied the effects of additional elements experimentally and, by comparison with electronic-structure calculations, found two more key parameters (approximately representing bond strength and electronegativity), critical for the design of practical elastic properties. We discuss dislocation-free plastic deformation of Gum Metal and its relation to the absolute elastic softening at an e/a value of 4.24, and finally we discuss the prospects for future applications of DFT in structural materials.
Membranes for Hydrogen Purification: An Important Step toward a Hydrogen-Based Economy
Authors: Nenoff Tina M. , Spontak Richard J. , Aberg Christopher M. 
Published: February 2011

AbstractProduction of pure molecular hydrogen is essential to the realization of the proposed “hydrogen economy” that could ultimately provide hydrogen as a clean, renewable source of energy; eliminate the industrialized world's dependence on petroleum; and reduce the generation of greenhouse gases linked to global warming. A crucial step in obtaining pure hydrogen is separating it from other gaseous compounds—mainly CO2—that often accompany hydrogen in industrial chemical reactions. Advanced membrane technology may prove to be the key to the successful, economical production of molecular hydrogen.Size-sieving glassy polymer membranes can separate H2 on the basis of its small size. Alternatively, reverse-selective rubbery polymers can expedite the passage and, hence, removal of CO2 due to its relatively high solubility in such membranes alone or in conjunction with dissociative chemical reactions. Transition-metal membranes and their alloys can adsorb H2 molecules, dissociate the molecules into H atoms for transport through interstitial sites, and subsequently recombine the H atoms to form molecular H2 again on the opposite membrane side. Microporous amorphous silica and zeolite membranes comprising thin films on a multilayer porous support exhibit good sorption selectivity and high diffusion mobilities for H2, leading to high H2 fluxes. Finally, carbon-based membranes, including carbon nanotubes, may be viable for H2 separation on the basis of selective surface flow and molecular sieving. A wide variety of materials challenges exist in hydrogen purification, and the objective of this issue of MRS Bulletin is to address those challenges and their potential solutions from basic principles.
Pharmaceutical Materials Science: An Active New Frontier in Materials Research
Authors: Elliott James , Hancock Bruno 
Published: February 2011

AbstractThe discipline of materials science has most commonly been associated with the study of structural or functional materials for engineering applications, such as metals, ceramics, and composites, but there are now, increasingly, great opportunities involving applications to soft matter, including polymers, powders, and biomaterials. The emerging discipline of pharmaceutical materials science attempts to apply physical principles common in materials science to challenges in such areas as drug delivery, control of drug form, manufacture and processing of nanoscopic and microscopic particle systems, and the structure and properties of bulk powders and their assemblies (e.g., tablets) for use in pharmaceutical applications. In this issue of MRS Bulletin, we have attempted to capture a snapshot of this rapidly developing new area of materials research, in order to bring it to the attention of the wider materials science community.
Particle Engineering: Fundamentals of Particle Formation and Crystal Growth
Authors: Lee Alfred Y. , Myerson Allan S. 
Published: February 2011

AbstractThe engineering of particles with customized properties optimized for dosage form manufacture (tablet, capsule, ointment, etc.) has long been a goal of the pharmaceutical industry. Particles can be designed through modification in the size, morphology, and packing arrangement of the solids. The most common approach in achieving this is through crystallization. In this bottom-up process, the two main steps, nucleation and crystal growth, both play a decisive role in shaping the quality of the final crystalline product. In this review, the role of nucleation and crystal growth in controlling particle properties is discussed, and examples are provided that demonstrate the variation in solid-state properties as a function of size, habit (morphology), and internal structure of the particles. In addition, the role of particle properties in product performance and dosage form development of pharmaceuticals is also discussed.
Materials Advances through Aberration-Corrected Electron Microscopy
Authors: Pennycook S.J. , Varela M. , Hetherington C.J.D. , Kirkland A.I. 
Published: February 2011

AbstractOver the last few years, the performance of electron microscopes has undergone a dramatic improvement, with achievable resolution having more than doubled. It is now possible to probe individual atomic sites in many materials and to determine atomic and electronic structure with single-atom sensitivity. This revolution has been enabled by the successful correction of the dominant aberrations present in electron lenses. In this review, the authors present a brief overview of these instrumental advances, emphasizing the new insights they provide to several areas of materials research.
Formation of Bulk Metallic Glasses and Their Composites
Authors: Li Y. , Poon S. J. , Shiflet G. J. , Xu J. , Kim D. H. , Löffler J. F. 
Published: February 2011

AbstractA great expansion in the number of alloy compositions known to give bulk metallic glasses (BMGs) has occurred in recent years. This progress is reviewed, and factors contributing to glass-forming ability are discussed. Practical strategies for pinpointing compositions with optimum glass-forming ability are presented, with examples of their use. Consideration is also given to the wide range of possibilities for BMG-based composites.
Mechanical Properties of Bulk Metallic Glasses
Authors: Yavari A. R. , Lewandowski J. J. , Eckert J. 
Published: February 2011

AbstractIn the absence of dislocation-mediated crystallographic slip, room-temperature deformation in metallic glasses occurs in thin shear bands initially only ∼10 nm thick. A sharp drop in viscosity (shear softening) occurs in deformed glassy matter and facilitates additional flow in existing shear bands. This further localization of plastic flow leads to shearing-off failure without any significant macroscopic plasticity.However, whereas most bulk metallic glasses fail in this manner, some undergo surprisingly extensive plastic deformation (in some cases, up to 50% or more) in compression or bending. When this occurs, the flow is “jerky,” as indicated by serrated stress–strain curves. Each serration may correspond to the emission of a shear band that then ceases to operate, at least temporarily, despite the predicted shear softening. As elastic energy is converted to heat during shear, temperatures rise sharply at or near shear bands. This heating may lead to the growth of nanocrystals that then block propagation of shear bands and cracks. The understanding of the dependence of mechanical response of metallic glasses on intrinsic (elastic constants, chemistry) and extrinsic factors (shapes, flaws) is the subject of intense current interest.
Focused Ion Beam Microscopy and Micromachining
Authors: Volkert C. A. , Minor A. M. 
Published: February 2011

AbstractThe fairly recent availability of commercial focused ion beam (FIB) microscopes has led to rapid development of their applications for materials science. FIB instruments have both imaging and micromachining capabilities at the nanometer–micrometer scale; thus, a broad range of fundamental studies and technological applications have been enhanced or made possible with FIB technology. This introductory article covers the basic FIB instrument and the fundamentals of ion–solid interactions that lead to the many unique FIB capabilities as well as some of the unwanted artifacts associated with FIB instruments. The four topical articles following this introduction give overviews of specific applications of the FIB in materials science, focusing on its particular strengths as a tool for characterization and transmission electron microscopy sample preparation, as well as its potential for ion beam fabrication and prototyping.
Microscopy and Microanalysis of Reverse-Osmosis and Nanofiltration Membranes
Authors: Cahill David G. , Freger Viatcheslav , Kwak Seung-Yeop 
Published: February 2011

AbstractThe polyamide active layers of commercial reverse-osmosis and nanofiltration membranes are examples of nanoscale functional materials that challenge the state of the art of materials characterization. The active layer is only ∼100 nm thick, and because the active layer is formed by a process of interfacial polymerization, the structure and composition of the membrane is highly inhomogeneous. Even such basic physical and chemical properties of the membrane as the atomic density, swelling in water, distribution of charged species, and the mobility of water and ions, are poorly understood. In this article, we briefly review progress in the characterization of polyamide separation membranes using transmission electron microscopy, atomic force microscopy, vibrational spectroscopy, positron annihilation, nuclear magnetic resonance, and Rutherford backscattering spectrometry. Advances in the microanalysis methods applicable to these complex materials will advance fundamental understanding of the structure–property relationships of polymer membranes and further the long-term goal of synthesizing membranes with improved performance.
Three-Dimensional Materials Science: An Intersection of Three-Dimensional Reconstructions and Simulations
Authors: Thornton Katsuyo , Poulsen Henning Friis 
Published: February 2011

AbstractThe recent development of experimental techniques that rapidly reconstruct the three-dimensional microstructures of solids has given rise to new possibilities for developing a deeper understanding of the evolution of microstructures and the effects of microstructures on materials properties. Combined with three-dimensional (3D) simulations and analyses that are capable of handling the complexity of these microstructures, 3D reconstruction, or tomography, has become a powerful tool that provides clear insights into materials processing and properties. This introductory article provides an overview of this emerging field of materials science, as well as brief descriptions of selected methods and their applicability.
Accessing Inaccessible Interfaces: In Situ Approaches to Materials Tribology
Authors: Sawyer W. Gregory , Wahl Kathryn J. 
Published: February 2011

AbstractThe field of materials tribology has entered a phase of instrumentation and measurement that involves accessing and following the detailed chemical, structural, and physical interactions that govern friction and wear. Fundamental tribological research involves the development of new experimental methods capable of monitoring phenomena that occur within the life of a sliding contact. Measuring friction phenomena while the process is ongoing is a major improvement over earlier techniques that required the surfaces to be separated and analyzed, thereby interrupting the friction-causing event and modifying surface conditions. In the past, MRS Bulletin has highlighted how in situ approaches can greatly enhance our understanding of materials structure, processing, and performance. This issue highlights in situ approaches as applied to materials tribology, namely, the study of contacting surfaces and interfaces in relative motion.
Fundamental Studies of Nanometer-Scale Wear Mechanisms
Authors: Bennewitz R. , Dickinson J.T. 
Published: February 2011

AbstractFundamental processes of wear include the rupture of single chemical bonds and the displacement of atoms or small clusters by mechanical action. Experimental studies of such processes have become feasible with the development of scanning probe microscopy. The small volume affected in these experiments overlaps with the size scale of large atomistic simulations, making a direct comparison possible. The complexity of real-world wear processes is reduced in most nanometer-scale experiments, for example, by probing surfaces of single crystals or by establishing and maintaining carefully controlled environments, including ultraclean conditions. The studies address the onset and topography of wear, the formation of debris structures, the interplay of mechanical and chemical action, the role of ultrathin films, the role of crystal defects in wear processes, and temporal and thermal effects.
Carbon Nanotube Electroactive Polymer Materials: Opportunities and Challenges
Authors: Qu Liangti , Peng Qiang , Dai Liming , Spinks Geoffrey M. , Wallace Gordon G. , Baughman Ray H. 
Published: February 2011

AbstractCarbon nanotubes (CNTs) with macroscopically ordered structures (e.g., aligned or patterned mats, fibers, and sheets) and associated large surface areas have proven promising as new CNT electroactive polymer materials (CNT-EAPs) for the development of advanced chemical and biological sensors. The functionalization of CNTs with many biological species to gain specific surface characteristics and to facilitate electron transfer to and from them for chemical- and bio-sensing applications is an area of intense research activity.Mechanical actuation generated by CNT-EAPs is another exciting electroactive function provided by these versatile materials. Controlled mechanical deformation for actuation has been demonstrated in CNT mats, fibers, sheets, and individual nanotubes. This article summarizes the current status and technological challenges for the development of electrochemical sensors and electromechanical actuators based on carbon nanotube electroactive materials.
Factors That Will Influence Oil and Gas Supply and Demand in the 21st Century
Authors: Holditch Stephen A. , Chianelli Russell R. 
Published: February 2011

AbstractA recent report published by the National Petroleum Council (NPC) in the United States predicted a 50–60% growth in total global demand for energy by 2030. Because oil, gas, and coal will continue to be the primary energy sources during this time, the energy industry will have to continue increasing the supply of these fuels to meet this increasing demand. Achieving this goal will require the exploitation of both conventional and unconventional reservoirs of oil and gas in an environmentally acceptable manner. Such efforts will, in turn, require advancements in materials science, particularly in the development of materials that can withstand high-pressure, high-temperature, and high-stress conditions.
Solar Energy Conversion Toward 1 Terawatt
Authors: Ginley David , Green Martin A. , Collins Reuben 
Published: February 2011

AbstractThe direct conversion of solar energy to electricity by photovoltaic cells or thermal energy in concentrated solar power systems is emerging as a leading contender for next-generation green power production. The photovoltaics (PV) area is rapidly evolving based on new materials and deposition approaches. At present, PV is predominately based on crystalline and polycrystalline Si and is growing at >40% per year with production rapidly approaching 3 gigawatts/year with PV installations supplying <1% of energy used in the world. Increased cell efficiency and reduced manufacturing expenses are critical in achieving reasonable costs for PV and solarthermal. CdTe thin-film solar cells have reported a manufactured cost of $1.25/watt. There is also the promise of increased efficiency by use of multijunction cells or hybrid devices organized at the nanoscale. This could lead to conversion efficiencies of greater than 50%. Solar energy conversion increasingly represents one of the largest new businesses currently emerging in any sector of the economy.
Road Transportation Vehicles
Authors: Carpenter Joseph A. , Gibbs Jerry , Pesaran Ahmad A. , Marlino Laura D. , Kelly Kenneth 
Published: February 2011

AbstractIn many industrial countries, road transportation accounts for a significant portion of the country's energy consumption. In developing countries, the use of energy for transportation is on the rise. The recent increase in petroleum prices, expanding world economic prosperity, the probable peaking of conventional petroleum production in the coming decades, and concerns about global climate changes require efforts to increase the efficiency of the use of, and develop alternatives for, petroleum-based fuels used in road transportation. The energy efficiency of a vehicle could be improved in several ways: lightweighting the vehicle structure and powertrain using advanced materials and designs, improving the efficiency of the internal combustion engine, reducing tire rolling resistance, and hybridization. Each of these efforts will require improvements in materials and processes.
Solid-State Lighting
Authors: Humphreys Colin J. 
Published: February 2011

AbstractElectricity generation is the main source of energy-related greenhouse gas emissions and lighting uses one-fifth of its output. Solid-state lighting using light-emitting diodes (LEDs) is poised to reduce this value by at least 50%, so that lighting will then use less than one-tenth of all electricity generated. LED lighting will provide reductions of at least 10% in fuel consumption and carbon dioxide emissions from power stations within the next 5–10 years. Even greater reductions are likely on a 10–20-year timescale.
Nanoporous Metals for Catalytic and Optical Applications
Authors: Ding Yi , Chen Mingwei 
Published: February 2011

AbstractNanoporous metals (NPMs) made by dealloying represent a class of functional materials with the unique structural properties of mechanical rigidity, electrical conductivity, and high corrosion resistance. They also possess a porous network structure with feature dimensions tunable within a wide range from a few nanometers to several microns. Coupled with a rich surface chemistry for further functionalization, NPMs have great potential for applications in heterogeneous catalysis, electrocatalysis, fuel cell technologies, biomolecular sensing, surface-enhanced Raman scattering (SERS), and plasmonics. This article summarizes recent advances in some of these areas and, in particular, we focus on the discussion of microstructure, catalytic, and optical properties of nanoporous gold (NPG). With advanced electron microscopy, three-dimensional tomographic reconstructions of NPG have been realized that yield quantitative characterizations of key morphological parameters involved in the intricate structure. Catalytic and electrocatalytic investigations demonstrate that bare NPG is already catalytically active for many important reactions such as CO and glucose oxidation. Surface functionalization with other metals, such as Pt, produces very efficient electrocatalysts, which have been used as promising fuel cell electrode materials with very low precious metal loading. Additionally, NPG and related materials possess outstanding optical properties in plasmonics and SERS. They hold promise to act as highly active, stable, and economically affordable substrates in high-performance instrumentation applications for chemical inspection and biomolecular diagnostics. Finally, we conclude with some perspectives that appear to warrant future investigation.
Proton Conduction in Solids: Bulk and Interfaces
Authors: Norby Truls 
Published: February 2011

AbstractTruly proton-conducting materials would have an immense impact on sustainable energy technologies for the 21st century, through efficient fuel cells, electrolyzers, and gas-separation membranes. However, proton conduction combined with materials stability seems difficult to achieve, and some hurdles and pathways are outlined in this article. Problems, possibilities, and artifacts of transport across and along interfaces are discussed, linked mainly to space-charge layer properties and engineering of the grain-boundary core and to water in nanovoids. The importance of protons in many semiconducting functional oxides is also explained. At lower temperatures and in humid environments, the presence of protonated cation vacancies (Ruetschi defects) is predicted and is expected to play an important role in photoelectrochemistry, catalysis, and surface transport.