bluuebunny/crossref_metadata_2025_split huggingface dataset:
Self-Assembly in Materials Synthesis
Authors: Tirrell Matthew V. , Katz Alexander 
Published: February 2011

AbstractThe synthesis of materials via self-assembly typically involves the spontaneous and reversible organization of small building blocks for the purpose of creating conglomerate structures over larger length scales. This introductory article describes self-assembly processes on several length scales, from subnanometer up to millimeter scales, and briefly summarizes some of the incredible diversity of materials that exhibit selfassembly. Articles in this issue cover self-assembly using zeolitic structures, organic molecular crystals, block copolymers, surfactants, mesoscale templates, and soluble crystallization additives. Keywords: block copolymers, materials synthesis, self-assembly, surfactants, templates, zeolites.
Biomimetic Mineralization/Synthesis of Mesoscale Order in Hybrid Inorganic–Organic Materials via Nanoparticle Self-Assembly
Authors: Cölfen Helmut , Yu Shu-Hong 
Published: February 2011

AbstractThe organization of nanostructures across several length scales by self-assembly is a key challenge in the design of advanced materials. In meeting this challenge, materials scientists can learn much from biomineralization processes in nature. These processes result in hybrid inorganic–organic materials with exquisite and optimized properties, complex forms, and hierarchical order over extended length scales.Biominerals are usually produced in the presence of an insoluble organic template as well as soluble molecules, which control inorganic crystallization, growth, and selfassembly. These processes can be mimicked successfully, resulting in inorganic–organic hybrid materials with complex form and mesoscale order via a nanoparticle selfassembly process.Various strategies can be applied, including the balancing of aggregation and crystallization, transforming and reorganizing of pre-formed nanoparticle building blocks, and face-selective coding of nanoparticle surfaces by additives for controlled self-assembly. The underlying principles of biomimetic mineralization will be described, along with selected examples showing that while much has already been achieved, the perfection of natural systems is still out of reach.
Nanopatterning with UV Optical Lithography
Authors: Rothschild M. , Bloomstein T. M. , Efremow N. , Fedynyshyn T. H. , Fritze M. , Pottebaum I. , Switkes M. 
Published: February 2011

AbstractOptical lithography at ultraviolet (UV) wavelengths is the standard process for patterning 90-nm state-of-the-art devices in the semiconductor industry, and extensions to 45 nm and below are currently being explored. With such high resolution, the inherent high throughput of optical lithography will enable the development of a broad range of applications beyond semiconductor electronics. In this article, we will review progress toward nanopatterning with UV light in a variety of materials and geometries.The common thread is the use of short wavelengths, 193 nm or 157 nm, coupled with immersion to further reduce the effective wavelength. Densely spaced, 32-nm (and even smaller) features have been patterned, facilitating the future preparation of large-area, deeply scaled microelectronics, nanophotonics, nanobiology, and molecular-scale self-assembly.
Block Copolymer Lithography: Merging “Bottom-Up” with “Top-Down” Processes
Authors: Hawker Craig J. , Russell Thomas P. 
Published: February 2011

AbstractAs the size scale of device features becomes ever smaller, conventional lithographic processes become increasingly more difficult and expensive, especially at a minimum feature size of less than 45 nm. Consequently, to achieve higher-density circuits, storage devices, or displays, it is evident that alternative routes need to be developed to circumvent both cost and manufacturing issues.An ideal process would be compatible with existing technological processes and manufacturing techniques; these strategies, together with novel materials, could allow significant advances to be made in meeting both short-term and long-term demands for higher-density, faster devices. The self-assembly of block copolymers (BCPs), two polymer chains covalently linked together at one end, provides a robust solution to these challenges. As thin films, immiscible BCPs self-assemble into a range of highly ordered morphologies where the size scale of the features is only limited by the size of the polymer chains and are, therefore, nanoscopic.While self-assembly alone is sufficient for a number of applications in fabricating advanced microelectronics, directed, self-orienting, self-assembly processes are also required to produce complex devices with the required density and addressability of elements to meet future demands. Both strategies require the design and synthesis of polymers that have well-defined characteristics such that the necessary fine control over the morphology, interfacial properties, and simplicity of processes can be realized. By combining tailored self-assembly processes (a “bottom-up” approach) with microfabrication processes (a “top-down” approach), the ever-present thirst of the consumer for faster, better, and cheaper devices can be met in very simple, yet robust, ways. The integration of novel chemistries with the manipulation of self-assembly will be treated in this article.
Quantum Information
Authors: Davidovich Luiz 
Published: February 2011

AbstractThe following article is based on the plenary address by Luiz Davidovich (Federal University of Rio de Janeiro), presented on April 14, 2004, at the 2004 MRS Spring Meeting in San Francisco. The field of quantum information is a discipline that aims to investigate methods for characterizing, transmitting, storing, compressing, and computationally utilizing the information carried by quantum states. It owes its rapid development over the last few years to several factors: the ability, developed in several laboratories, to control and measure simple microscopic systems; the discovery of fast quantum algorithms; and the recognition that Moore's law will soon lead to the single-atom limit of elementary computing gates.Cryptography and quantum computing are among the main applications in the field.They rely on the subtle and fundamental properties of the quantum world: the unavoidable disturbance associated with measurement, the superposition principle, and the nonlocal properties of entangled states. Progress in this area is intimately connected to a deep understanding of quantum physics: recent achievements include the experimental demonstration of teleportation and detailed investigations of the role of the environment in the quantum–classical transition. This article reviews basic concepts and recent developments in the field of quantum information, emphasizing the close ties between fundamental research and possible applications.
Microengineering the Environment of Mammalian Cells in Culture
Authors: Chen Christopher S. , Jiang Xingyu , Whitesides George M. 
Published: February 2011

AbstractAssays based on observations of the biological responses of individual cells to their environment have the potential to make enormous contributions to cell biology and biomedicine.To carry out well-defined experiments using cells, both the environments in which the cells live and the cells themselves must be well defined. Cell-based assays are now plagued by inconsistencies and irreproducibility, and a primary challenge in the development of informative assays is to understand the fundamental bases for these inconsistencies and to limit them. It now seems that multiple factors may contribute to the variability in the response of individual cells to stimuli; some of these factors may be extrinsic to the cells, some intrinsic. New techniques based on microengineering—especially using soft lithography to pattern surfaces at the molecular level and to fabricate microfluidic systems—have provided new capabilities to address the extrinsic factors. This review discusses recent advances in materials science that provide well-defined physical environments that can be used to study cells, both individually and in groups, in attached culture. It also reviews the challenges that must be addressed in order to make cell-based assays reproducible.
Investigating the Function of Ion Channels in Tethered Lipid Membranes by Impedance Spectroscopy
Authors: Terrettaz Samuel , Vogel Horst 
Published: February 2011

AbstractThe function of biologically important ion channels can be measured in supported lipid membranes by impedance spectroscopy. This approach offers substantial advantages over traditional electrophysiological measurements. In this article, we present an overview of the field, with a special emphasis on the reconstitution of ion channels in lipid bilayers tethered to gold electrodes and the modulation of their channel activity by specific ligand binding.
Polymer–Fullerene Bulk Heterojunction Solar Cells
Authors: Janssen René A. J. , Hummelen Jan C. , Sariciftci N. Serdar 
Published: February 2011

AbstractNanostructured phase-separated blends, or bulk heterojunctions, of conjugated polymers and fullerene derivatives form a very attractive approach to large-area, solid-state organic solar cells. The key feature of these cells is that they combine easy processing from solution on a variety of substrates with good performance. Efficiencies of up to 5% in solar light have been achieved, and lifetimes are increasing to thousands of hours. Further improvements can be expected and some of the promising strategies towards that goal are presented in this article.
Degradation of SiC High-Voltage pin Diodes
Authors: Ha Seoyong , Bergman J. P. 
Published: February 2011

AbstractThe recent discovery of forward-voltage degradation in SiC pin diodes has created an obstacle to the successful commercialization of SiC bipolar power devices. Accordingly, it has attracted intense interest around the world. This article summarizes the progress in both the fundamental understanding of the problem and its elimination.The degradation is due to the formation of Shockley-type stacking faults in the drift layer, which occurs through glide of bounding partial dislocations. The faults gradually cover the diode area, impeding current flow. Since the minimization of stress in the device structure could not prevent this phenomenon, its driving force appears to be intrinsic to the material. Stable devices can be fabricated by eliminating the nucleation sites, namely, dissociated basal-plane dislocations in the drift layer.Their density can be reduced by the conversion of basal-plane dislocations propagating from the substrate into threading dislocations during homoepitaxy.
Triblock Copolymer as an Effective Membrane-Sealing Material
Authors: Wu Guohui , Frey Shelli L. , Maskarinec Stacey A. , Lee Ka Yee C. 
Published: February 2011

An intact cell membrane serves as a permeable barrier, regulating the influx and efflux of ions and small molecules. When the integrity of the membrane is compromised, its barrier function is also disrupted, threatening the survival of the cell. Triblock copolymer surfactants of the form poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) have been shown to help seal structurally damaged membranes, arresting the leakage of intracellular materials.In order to understand how this particular family of triblock copolymers helps seal damaged membranes, model lipid monolayer and bilayer systems have been used to unravel the nature of the lipid/copolymer interaction. The copolymer surfactant is found to selectively insert into structurally compromised membranes, thus localizing its sealing effect on the damaged regions. The inserted polymer is “squeezed out” when the lipid packing density is increased, suggesting a mechanism for the cell to be rid of the polymer when the membrane integrity is restored.
Ultrafast Lasers in Materials Research
Authors: Cahill David G. , Yalisove Steve M. 
Published: February 2011

AbstractWith the availability of off-the-shelf commercial ultrafast lasers, a small revolution in materials research is underway, as it is now possible to use these tools without being an expert in the development of the tools themselves. Lasers with short-duration optical pulses—in the sub-picosecond (less than one-trillionth of a second) range—are finding a variety of applications, from basic research on fast processes in materials to new methods for microfabrication by direct writing. A huge range of pulse energies are being used in these applications, from less than 1 nJ (a billionth of a joule) to many joules.
Silicon Surface Morphologies after Femtosecond Laser Irradiation
Authors: Tull Brian R. , Carey James E. , Mazur Eric , McDonald Joel P. , Yalisove Steven M. 
Published: February 2011

AbstractIn this article, we present summaries of the evolution of surface morphology resulting from the irradiation of single-crystal silicon with femtosecond laser pulses. In the first section, we discuss the development of micrometer-sized cones on a silicon surface irradiated with hundreds of femtosecond laser pulses in the presence of sulfur hexafluoride and other gases. We propose a general formation mechanism for the surface spikes. In the second section, we discuss the formation of blisters or bubbles at the interface between a thermal silicon oxide and a silicon surface after irradiation with one or more femtosecond laser pulses. We discuss the physical mechanism for blister formation and its potential use as channels in microfluidic devices.
Density Functional Theory in Surface Science and Heterogeneous Catalysis
Authors: Nørskov J.K. , Scheffler M. , Toulhoat H. 
Published: February 2011

AbstractSolid surfaces are used extensively as catalysts throughout the chemical industry, in the energy sector, and in environmental protection. Recently, density functional theory has started providing new insight into the atomic-scale mechanisms of heterogeneous catalysis, helping to interpret the large amount of experimental data gathered during the last decades. This article shows how density functional theory can be used to describe the state of the surface during reactions and the rate of catalytic reactions. It will also show how we are beginning to understand the variation in catalytic activity from one transition metal to the next. Finally, the prospects of using calculations to guide the development of new catalysts in industry will be discussed.
Polymer Membranes for Hydrogen Separations
Authors: Perry John D. , Nagai Kazukiyo , Koros William J. 
Published: February 2011

AbstractThe development of a hydrogen-based economy would generate a substantial necessity for efficient means of collecting hydrogen with a relatively high purity. Membrane separations play a major role in the separation of hydrogen gas from various gas mixtures, and this article discusses the use of polymeric materials to produce these membranes. After a review of the historical use of polymeric membranes and some background information regarding mechanisms of gas transport in membranes, this article will review the work that has been done in the two major classes of hydrogen separation membranes: hydrogen-selective membranes and hydrogen-rejective membranes. In hydrogen-selective membranes, the very small size of the hydrogen molecule is exploited to allow rapid diffusion of hydrogen through the membrane while excluding other gases. Hydrogen-rejective membranes use the significantly higher sorption of other gases to overcome the advantages of the small size of the hydrogen molecule. The discussion of these two types of membranes will be followed by a presentation of the current state of the art with regard to polymeric membranes for hydrogen separation and a discussion of the predictions for future applications and advancements in this area.
Polymeric Facilitated Transport Membranes for Hydrogen Purification
Authors: Hägg May-Britt , Quinn Robert 
Published: February 2011

AbstractThe most widely used method of hydrogen production, steam methane reforming, yields a product stream consisting mainly of hydrogen (H2) and carbon dioxide (CO2). Purification of this product is currently accomplished using amine-based acid gas scrubbers or pressure swing adsorption technology. Membranes are well suited to bulk CO2 removal and offer a viable alternative to these established technologies. This review considers one type of such membranes, polymeric facilitated transport membranes. These membranes selectively permeate CO2 by means of a reversible reaction between the gas and the membrane material. In addition, the membrane provides a barrier to H2 permeation. The result is removal of the CO2 contaminant and recovery of the H2 product at high pressure, eliminating the need for recompression prior to use or storage. A wide range of polymeric materials have been investigated, including ion-exchange resins, hydrophilic polymers blended with CO2-reactive salts, polyelectrolytes, fixed-site carrier polymers, and biomimetic materials. This review provides a description of the reaction chemistry of facilitated transport, a summary of membrane permselective properties, and suggestions for future research efforts.
Microporous Silica and Zeolite Membranes for Hydrogen Purification
Authors: Verweij Henk , Lin Y.S. , Dong Junhang 
Published: February 2011

AbstractMicroporous amorphous silica and zeolite membranes are made as thin films on a multilayer porous support. The membranes have a network of connected micropores with ∼0.5–nm diameters. Net transport of small molecules on this network occurs under the driving force of a gradient in chemical potential. Favorable combinations of sorption selectivity and diffusion mobility in the membrane materials lead to high H2fluxes and good selectivity with respect to other gases. The membranes show potential for application in H2separation under harsh conditions. Amorphous silica membranes show very high H2fluxes because they can be made very thin; silicalite-type zeolite membranes are expected to have a better operational stability. To make the membranes a viable option, improvements are needed in reducing membrane defects and manufacturing costs and enhancing reproducibility and operational stability. This article summarizes the state of the art, provides relevant definitions, and outlines the base design and long-term specifications of viable supported membrane structures. This is followed by an overview of transport properties, synthesis, and operational stability of the membrane and the supporting structures. Directions for future research programs are provided by demonstrating how the selection of the actual membrane composition and supporting structure can be derived from an application-based design. The success of such a design depends critically on fundamental studies of membrane transport, strength, and operational stability.
The Intersection of Biology and Materials Science
Authors: Whitesides George M. , Wong Amy P. 
Published: February 2011

AbstractThis article is based on the plenary address given by George M. Whitesides of Harvard University on March 30, 2005, at the Materials Research Society Spring Meeting in San Francisco. Materials science and biomedicine are arguably two of the most exciting fields in science today. Research at the border between them will inevitably be a major focus, and the applications of materials science to problems in biomedicine—that is, biomaterials science—will bud into an important new branch of materials science. Accelerating the growth of this area requires an understanding of two very different fields, and being both thoughtful and entrepreneurial in considering “Why?” “How?” and “Where?” to put them together. In this fusion, biomedicine will, we believe, set the agenda; materials science will follow, and materials scientists must learn biology to be effective.
Pharmaceutical Cocrystals: An Emerging Approach to Physical Property Enhancement
Authors: Jones William , Motherwell W.D. Samuel , Trask Andrew V. 
Published: February 2011

AbstractPharmaceutical cocrystals are crystalline molecular complexes containing therapeutic molecules. They represent an emerging class of pharmaceutical materials offering the prospect of optimized physical properties. This article highlights important opportunities and challenges associated with the design and synthesis of pharmaceutical cocrystals. Cocrystallization is first placed into context with the more established approaches to physical property optimization of polymorph, hydrate, and salt selection. A directed, intermolecular-interaction-based approach to cocrystal design is described. The enhancement of specific physical properties, such as dissolution rate and physical stability, is illustrated by summarizing several recent reports. Synthetic approaches to cocrystallization are considered; in particular, the selectivity and screening-related opportunities afforded by solid-state grinding and solvent-drop grinding methods are discussed. Finally, an outlook on future developments summarizes the growth potential in this field, especially with regard to targeted, informatics-driven cocrystal screening approaches.
Intelligent Biomaterials as Pharmaceutical Carriers in Microfabricated and Nanoscale Devices
Authors: Peppas Nicholas A. 
Published: February 2011

AbstractThe emergence of micro- and nanoscale science and engineering has provided new avenues for engineering materials with macromolecular and even molecular-scale precision, leading to diagnostic and therapeutic technologies that will revolutionize the way healthcare is administered. Biomaterials have evolved from off-the-shelf products to materials designed with molecular precision to exhibit the desired properties for a specific application, often mimicking biological systems. Controlling interactions at the level of natural building blocks, from proteins to cells, facilitates the novel exploration, manipulation, and application of living systems and biological phenomena. In addition, polymer networks with precisely engineered binding sites have been created via molecular imprinting, where functional monomers are preassembled with a target molecule and then the structure is locked with network formation. Nanoscale science and engineering have accelerated the development of novel drug delivery systems and led to enhanced control over how a given pharmaceutical is administered, helping biological potential to be transformed into medical reality. Micro- and nanoscale devices have been fabricated using integrated-circuit processing techniques, enabling strict temporal control over drug release. The advantages of these microdevices include simple release mechanisms, very accurate dosing, the capability of complex release patterns, the potential for local delivery, and possible biological drug stability enhancement by means of storage in a microvolume that can be precisely controlled. In particular, the development of polymer systems that are able to interact with their environment in a thermodynamically responsive manner has led to novel intelligent biomaterials and applications. Intelligent biomedical materials can be used for the delivery of drugs, peptides, and proteins; as targeting agents for site-specific delivery; or as components for the preparation of protein or drug conjugates. These intelligent materials are attractive options as functional components in micro- and nanodevices because of the ease with which recognition and actuation properties can be precisely tailored. Recent developments in intelligent materials and nano- or microdevices for drug delivery systems are the emphasis of this review, which addresses the use of intelligent biomedical materials as carriers for the development of novel pharmaceutical formulations.