bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nonvolatile Magnetoresistive Random-Access Memory Based on Magnetic Tunnel Junctions
Authors: Grynkewich G. , Åkerman J. , Brown P. , Butcher B. , Dave R.W. , DeHerrera M. , Durlam M. , Engel B.N. , Janesky J. , Pietambaram S. , Rizzo N.D. , Slaughter J.M. , Smith K. , Sun J.J. , Tehrani S. 
Published: February 2011

AbstractMagnetoresistive random-access memory (MRAM) is a new memory technology that is nearing commercialization. MRAM integrates a magnetic tunnel junction (MTJ) device with standard silicon-based microelectronics, resulting in a combination of qualities not found in other memory technologies. For example, MRAM is nonvolatile, has unlimited read and write endurance, and is capable of high-speed read and write operations. In this article, we will describe the fundamentals of an MTJ-based MRAM as well as recent important technology developments in the areas of magnetic materials and memory cell architecture. In addition, we will compare the present and future capabilities of MRAM to those of existing memory technologies such as static RAM and flash memory.
Current Status of Ferroelectric Random-Access Memory
Authors: Arimoto Yoshihiro , Ishiwara Hiroshi 
Published: February 2011

AbstractThe current status of ferroelectric random-access memory (FeRAM) technology is reviewed in this article. Presented first is the status of conventional FeRAM, in which the memory cells are composed of ferroelectric capacitors to store the data and cell-selection transistors to access the selected capacitors. Discussed next are recent developments in the field. Pb(Zrx, Ti1–x)O3 (PZT) and SrBi2Ta2O9 (SBT) films are being used to produce 0.13 mμ and 0.18 μm FeRAM cells, respectively, with a stacked capacitor configuration; these cells are easily embedded into logic circuits. A new class of FeRAM called 6T4C—containing static RAM (SRAM) cells composed of six transistors (6T) and four ferroelectric capacitors (4C)—has been commercially produced. This type of FeRAM features a nondestructive readout operation, unlimited read/write cycling, and a fast access time of less than 10 ns. Lastly, the status of field-effect-transistor (FET)-type FeRAM is reviewed, emphasizing that the data retention time of a ferroelectric-gate FET has been improved to more than a month in recent studies.
Crystal–Melt Interfaces and Solidification Morphologies in Metals and Alloys
Authors: Hoyt J.J. , Asta M. , Haxhimali T. , Karma A. , Napolitano R.E. , Trivedi R. , Laird B.B. , Morris J.R. 
Published: February 2011

AbstractWhen liquids solidify, the interface between a crystal and its melt often forms branching structures (dendrites), just as frost spreads across a window. The development of a quantitative understanding of dendritic evolution continues to present a major theoretical and experimental challenge within the metallurgical community. This article looks at key parameters that describe the interface—excess free energy and mobility—and discusses how these important properties relate to our understanding of crystal growth and other interfacial phenomena such as wetting and spreading of droplets and nucleation of the solid phase from the melt. In particular, two new simulation methods have emerged for computing the interfacial free energy and its anisotropy:the cleaving technique and the capillary fluctuation method. These are presented, along with methods for extracting the kinetic coefficient and a comparison of the results to several theories of crystal growth rates.
Colloids under External Control
Authors: van Blaaderen Alfons 
Published: February 2011

AbstractThe ability of colloids to self-organize through a minimization of their free energy is a direct consequence of their well-defined thermodynamic temperature that manifests itself through the Brownian motion they perform. In this article, it will be shown that through the use of external fields such as electric and magnetic fields, gravity, structured or confining walls, and shear, this self-organization can be directed to make new advanced materials. Moreover, a start has been made toward colloidal model systems to study fundamental questions relating to materials science such as defect structure and dynamics, grain boundaries, wall and confinement effects, and tribology. Finally, we predict that the enhanced insights on how to use external fields will also lead to “smart” materials with properties that can be changed dynamically.
Colloidal Glasses
Authors: Poon Wilson C.K. 
Published: February 2011

AbstractThis article reviews recent advances in understanding amorphous glassy states in dense colloidal suspensions with or without short-range interparticle attractions. Experiments, theory, and simulation show that two kinds of glassy states are possible, dominated respectively by repulsion and attraction. Under suitable conditions, a small change in the interparticle potential can lead to a transition between these two kinds of colloidal glasses that entails sharp changes in material properties such as the shear modulus. This may provide novel routes for fine-tuning the properties of industrial pastes and slurries.
The Role of Nanoscale Forces in Colloid Dispersion Rheology
Authors: Wagner Norman J. , Bender Jonathan W. 
Published: February 2011

AbstractAdvances in our fundamental understanding of and control over interparticle colloidal forces have enhanced our ability to formulate stable, complex fluids with colloidal and/or nano-sized particles with specific rheological properties. This understanding stems from advances in experimental methods that probe these forces, either directly or indirectly, as well as theoretical treatments and simulation methods linking macroscopic suspension properties to the dynamics and interactions between colloidal particles. This article highlights recent experimental developments in the structure—property relationships for colloidal dispersions, with emphasis on the sensitivity of colloid rheology to nanometer-scale interactions. Examples of applications are used to illustrate these relationships.
High-Resolution 3D Imaging Microscopy Using Hard X-Rays
Authors: Schroer Christian G. , Cloetens Peter , Rivers Mark , Snigirev Anatoly , Takeuchi Akahisa , Yun Wenbing 
Published: February 2011

AbstractThe key strength of hard x-ray full-field microscopy is the large penetration depth of hard x-rays into matter, which allows one to image the interior of opaque objects. Combined with tomographic techniques, the three-dimensional inner structure of an object can be reconstructed without the need for difficult and destructive sample preparation. Projection microscopy and microtomography are now routinely available at synchrotron radiation sources. The resolution of these techniques is limited by that of the detector to 1 µm or slightly less. X-ray images and tomograms at higher spatial resolution can be obtained by x-ray optical magnification, for example, by using parabolic refractive x-ray lenses as a magnifying optic. Combining magnifying x-ray imaging with tomography allows one to reconstruct the three-dimensional structure of an object, such as a microprocessor chip, with resolution well below 1 µm. In x-ray scanning microscopy, the sample is scanned through a small-diameter beam. The great advantage of scanning microscopy is that x-ray analytical techniques such as fluorescence analysis, diffraction, and absorption spectroscopy can be used as contrast mechanisms in the microscope. In combination with tomography, fluorescence analysis makes it possible to reconstruct the distribution of different chemical elements inside an object (fluorescence microtomography), while combining absorption spectroscopy with tomography yields the distribution of different oxidation states of atomic species.
Turning Peapods into Double-Walled Carbon Nanotubes
Authors: Bandow S. , Hirahara K. , Hiraoka T. , Chen G. , Eklund P.C. , Iijima S. 
Published: February 2011

AbstractThe formation pathway to double-walled carbon nanotubes (DWNTs) from C60 encased within single-walled carbon nanotubes (peapods) is introduced in this article. Onedimensionally arranged C60 molecules coalesce gradually within the nanotube and change the structure to C60 dimers, trimers, tetramers, and so on as intermediates. In addition to these interesting structural transformations visualized in the nanotube space, the nanotube itself is very stable, and this structural stability is very important when using the interior of the nanotube as the reaction field or the space for molecular storage. In terms of optical absorption, the lowest energy absorption band for DWNTs, ∼0.65 eV, shows broadened and downshifted features as compared with that of SWNTs.We expect that this opticalabsorption feature will lead to the use of DWNTs in absorbing devices for optical-fiber communications. The Raman experiments give new information about the frequency of the C-C stretching-mode vibration for nanotubes with diameters of less than ∼1 nm, which shows a decrease in vibration frequency with decreasing tube diameter. This diameter dependence can be explained by an admixture of sp3 character in the C-C interaction. Therefore, the electronic and mechanical properties of nanotubes with diameters of <1 nm are expected to be different from nanotubes of the ∼1-nm-diameter class, and we anticipate that new phenomena will occur in small-diameter tubes.
Construction Materials: From Innovation to Conservation
Authors: Scrivener Karen , Van Damme Henri 
Published: February 2011

AbstractThis article serves to introduce the May 2004 issue of MRS Bulletin on Construction Materials: From Innovation to Conservation. By volume, building materials are by far the most widely used type of materials. The most common construction materials—concrete and wood—are paradigms of complex and hierarchical materials, with a microstructure extending quasi-continuously down to the nanoscale. In the past, most improvements have been obtained by modifying the microstructure at the largest scales, for instance, by reducing the macroporosity. Recent advances in our understanding of the interactions and microstructure development show that the major levers for improvement from now on will rely on surface and colloid science and the science of complex materials, often at the nanoscale. This can lead to remarkable properties, such as self-compaction and ultrahigh strength, and even new functionality, such as self-cleaning through photocatalysis. Construction materials face a wide range of challenges today, many of which are linked to the need for more sustainable development: reducing the consumption of raw materials, reducing the energy used in processing, and increasing service life. In many parts of the world, there is also an increasing need to repair, rehabilitate, and conserve old buildings. The articles in this issue touch on these challenges as well as the advances being made in construction materials through materials research.
Optically and Chemically Encoded Nanoparticle Materials for DNA and Protein Detection
Authors: Thaxton C. Shad , Rosi Nathaniel L. , Mirkin Chad A. 
Published: February 2011

AbstractNanoscale materials are beginning to have an impact in the field of molecular diagnostics. In particular, gold nanoparticles surface-functionalized with DNA have garnered much recent interest. Due to the unusual optical and catalytic properties of gold nanoparticle labels, several distinct advantages for assay readout have been realized. This review focuses on the progress made in our group over the past seven years in the development of particle surface chemistry and ultrasensitive protein and nucleic acid assays based upon DNA-functionalized gold nanoparticles. For DNA targets, experiments demonstrate that assays based upon gold nanoparticle labels have enhanced target specificity and in certain cases the sensitivity of polymerase chain reaction (PCR), without the need for target amplification. For protein targets, similar experiments demonstrate that assays based upon gold nanoparticles are up to one million times more sensitive than conventional protein detection methods. Recent data using human samples demonstrate the utility of such assays.
“Wave-Function Imaging” Studies of High-Tc Superconductivity
Authors: Slezak James A. , Lee Jinho , Davis J. C. 
Published: February 2011

AbstractHigh-temperature superconductivity in the cuprates emerges when the localized electrons of a Mott insulator become mobile due to carrier doping. Understanding both the electronic ground state and the excited states of these systems are key challenges in physics today. Angle-resolved photoemission spectroscopy (ARPES) and inelastic neutron-scattering (INS) studies have been remarkably successful in mapping the momentum-space characteristics of the cuprate electronic structure. However, since cuprate superconductivity develops from atomically localized electrons and exhibits nanoscale disorder, a pure momentum-space description is unlikely to be sufficient. Instead, simultaneous information on electronic structure at the nanoscale in real space, and throughout momentum space, is required. Here, we describe a combination of novel spectroscopic imaging scanning tunneling microscopy (SI-STM) techniques that we have developed to achieve these apparently contradictory aims, along with the outcome of a series of SI-STM studies of the electronic structure of Bi2Sr2CaCu2O8+x.
From Transistors to Lasers and Light-Emitting Diodes
Authors: Holonyak Nick 
Published: February 2011

AbstractThis article is based on the 2004 Von Hippel Award address by Nick Holonyak Jr. (University of Illinois at Urbana-Champaign). Holonyak received the award for “his many contributions to research and development in the field of semiconductors, not least for the first development of semiconductor lasers in the useful visible portion of the optical spectrum.” The talk was presented on Holonyak's behalf by Russell Dupuis on December 1, 2004, at the Materials Research Society Fall Meeting in Boston.With the discovery of the transistor by Bardeen and Brattain in 1947, and as a consequence of carrier injection and collection, the hole indeed became equal to the electron. The semiconductor took on new importance, as did the study of electron–hole recombination, first in the transistor materials Ge and Si, and then in III–V crystals (e.g., GaAs and GaP). Beyond Si and its indirect-gap and heterojunction limitations, the directgap III–V materials, particularly III–V alloys, made possible lasers and light-emitting diodes (LEDs)—and thus optoelectronics.The direct-gap III–V alloy LED after four decades of development exceeds in performance the incandescent lamp (as well as other forms of lamps) in much of the visible range. Beyond growing display applications, it has put conventional lighting under longrange threat with a semiconductor lamp—an “ultimate lamp” that promises unusual performance and energy savings. In principle, the LED or laser, basically a p–n junction, is an ultimate lamp that cannot be exceeded.
Biomaterials for Regenerative Medicine
Authors: Stupp Samuel I. 
Published: February 2011

AbstractThe following article is based on a presentation given by Samuel I. Stupp of Northwestern University as part of Symposium X—Frontiers of Materials Research on April 13, 2004, at the Materials Research Society Spring Meeting in San Francisco. Materials designed at the molecular and supramolecular scales to interact with cells, biomolecules, and pharmaceuticals will have a profound impact on technologies targeting the regeneration of body parts. Materials science is a great partner to stem cell biology, genomics, and proteomics in crafting the scaffolds that will effectively regenerate tissues lost to trauma, disease, or genetic defects. The repair of humans should be minimally invasive, and thus the best scaffolds would be liquids programmed to create materials inside our bodies. In this regard, self-assembling materials will play a key role in future technologies. This article illustrates how molecules are designed to assemble into cell scaffolds for human repair and provides examples relevant to brain damage, fractures of the skeleton, spinal cord injuries leading to paralysis, and diabetes.
Fuel Cells: The Next Evolution
Authors: Lashway Robert W. 
Published: February 2011

AbstractThe articles in this issue of MRS Bulletin highlight the enormous potential of fuel cells for generating electricity using multiple fuels and crossing a wide range of applications. Fuel cells convert chemical energy directly into electrical energy, and as a powergeneration module, they can be viewed as a continuously operating battery.They take in air (or pure oxygen, for aerospace or undersea applications) and hydrocarbon or hydrogen fuel to produce direct current at various outputs. The electrical output can be converted and then connected to motors to generate much cleaner and more fuelefficient power than is possible from internal combustion engines, even when combined with electrical generators in today's hybrid engines. The commercialization of these fuel cell technologies is contingent upon additional advances in materials science that will suit the aggressive electrochemical environment of fuel cells (i.e., both reducing an oxidizing) and provide ionic and electrical conductance for thousands of hours of operation.
An All-Ceramic Interconnect for Use in Solid-Oxide Fuel Cell Stacks
Authors: Morris Thomas A. , Barringer Eric A. , Kung Steven C. , McKain Rodger W. 
Published: February 2011

AbstractThis article summarizes a unique approach in which all-ceramic interconnects are used in place of metal interconnects in solid-oxide fuel cell (SOFC) stacks. The approach combines advanced SOFC materials with the manufacturing technology and infrastructure established for multilayer ceramic (MLC) packaging for the microelectronics industry. The MLC interconnect is fabricated using multiple layers of yttria-stabilized zirconia (YSZ) tape, with each layer containing conductive vias to provide for electrical current flow through the interconnect. The all-ceramic interconnect design facilitates uniform distribution of air and fuel gas to the respective electrodes of adjacent cells. The multilayer interconnects are fabricated using traditional MLC manufacturing processes. A detailed description of the processes for fabricating the all-ceramic interconnect is presented.To aid in moving from prototype fabrication to commercialization of these fuel cell systems, a detailed cost model has been used as a roadmap for commercial stack development. Cost model projections are presented for three different interconnect footprint sizes. These projections show an SOFC stack cost of less than $150 per kilowatt for the optimized SOFC stack design produced at high volume.
Carbonate Fuel Cell Technology and Materials
Authors: Farooque M. , Yuh C. , Maru H.C. 
Published: February 2011

AbstractHigh-temperature carbonate fuel cells are recognized as the cleanest and most efficient power generation option for commercial and industrial customers. The firstgeneration carbonate fuel cell plants have shown an electrical efficiency of 45–48%.The electrolyte in this fuel cell is a mixture of alkali carbonates, and it operates at a highenough temperature that the heat by-product can be used for cogeneration applications such as district heating, hot water, process steam, and absorption chilling for air conditioning. Alternatively, the heat by-product can be used with an unfired gas turbine for additional electrical generation. Depending on location, application, and load size, carbonate fuel cells are expected to achieve an overall energy efficiency of 65–80% in cogeneration and combined cycle applications. The cell hardware uses commonly available stainless steels. Electrode materials are nickel-based. Furthermore, standard, well-established manufacturing processes are employed. Therefore, carbonate fuel cells are well positioned to be cost-competitive with alternative technologies. Significant progress has been made in the development, manufacturing, product engineering, and field operation of carbonate fuel cell technology. Megawatt and submegawatt units are operating worldwide. A comprehensive review of carbonate fuel cell technology and materials are presented in this article.
Nanotechnology and DNA Delivery
Authors: Luo Dan 
Published: February 2011

AbstractNonviral DNA delivery systems have great therapeutic and prophylactic potential, but their clinical utility has been limited by three major barriers: (1) inefficient uptake by the cell, (2) insufficient release of DNA within the cell, and (3) ineffective nuclear targeting and transport. Since the size of most cells is in the micrometer regime and the space inside a cell is extremely crowded, ideal DNA delivery systems must be in the nanometer range. Advancements in nanoscale science and nanotechnology have provided us with novel nanoparticles that may overcome all of these barriers, leading to higher-efficiency DNA delivery. This review article will focus on the recent developments in nanoscale DNA delivery systems that consist of chemical dendrimers, DNA dendrimers, nanospheres, nanolayers, nanorods, and nanotubes. The future of DNA delivery systems that interface with nanotechnology is also discussed.
Gene Delivery by Immobilization to Cell-Adhesive Substrates
Authors: Bengali Zain , Shea Lonnie D. 
Published: February 2011

AbstractBiomaterials can potentially enhance the delivery of viral and nonviral vectors for both basic science and clinical applications.Vectors typically consist of nucleic acids (DNA, RNA) packaged with proteins, lipids, or cationic polymers, which facilitate cellular internalization and trafficking. These vectors can associate with biomaterials that support cell adhesion, a process we term substrate-mediated delivery. Substrate immobilization localizes the DNA and the delivery vector to the cellular microenvironment.The interaction between the vector and substrate must be appropriately balanced to mediate immobilization, yet allow for cellular internalization. Balancing the binding between the biomaterial and the vector is dependent upon the surface chemistries of the material and the vector, which can be designed to provide both specific (e.g., biotin–avidin, the strongest known noncovalent interaction between a protein and its ligand) and nonspecific (e.g., van der Waals) interactions. In this review, we describe the biomaterial and vector properties that mediate binding and gene transfer, identify potential applications, and present opportunities for further development.
Peptide-Enhanced Nucleic Acid Delivery
Authors: Bergen Jamie M. , Pun Suzie H. 
Published: February 2011

AbstractNumerous barriers, both extracellular and intracellular, hinder successful and efficient nonviral nucleic acid delivery. Due to their small size and ability to specifically recognize and interact with molecular targets, peptides can be incorporated as modular elements into synthetic nucleic acid delivery systems to overcome many of these barriers. Three classes of peptides that have frequently been integrated as components in nucleic acid delivery systems include cell-penetrating peptides (CPPs), endosomal release peptides, and nuclear localization sequences (NLSs).Various additional classes of peptides show promise for enhancing nucleic acid delivery by targeting cell surface receptors, inhibiting nuclease activity, and directing nucleic acids toward intracellular targets. In addition to a review of the various existing approaches to peptide-enhanced nucleic acid delivery, this article will discuss strategies for the development of new peptides and approaches for the incorporation of these peptides into nucleic acid delivery systems.