bluuebunny/crossref_metadata_2025_split huggingface dataset:
The US Department of Energy's Working Group on Photoelectrochemical Hydrogen Production: Promoting Technology-Enabling Breakthroughs in Semiconductor Materials Research
Authors: Garland Roxanne , Miller Eric L. 
Published: August 2010

AbstractPhotoelectrochemical (PEC) hydrogen production, using sunlight to split water, is an important enabling technology for a future “Green” economy which will rely, in part, on hydrogen as an energy currency. The traditional semiconductor-based PEC material systems studied to date, however, have been unable to meet all the performance, durability and cost requirements for practical hydrogen production. Technology-enabling breakthroughs are needed in the development of new, advanced materials systems, and toward this end, the U.S. Department of Energy’s Working Group on PEC Hydrogen Production is bringing together experts in analysis, theory, synthesis and characterization from the academic, industry and national-laboratory research sectors. Key Working Group activities, as described in this paper, include performing techno-economic analyses of large-scale PEC production systems and establishing standardized testing and screening protocols for candidate PEC materials systems. In addition, a number of Working Group “Task Forces” are focused on advancing critical PEC materials theory, synthesis and characterization capabilities for application in the research and development of broad-ranging materials systems of promise, including complex metal-oxide and -nitride compounds, amorphous silicon alloys, III-V semiconductors and the copper chalcopyrites. The current status of Working Group activities and progress is summarized.
Electronic Structure Properties of the Photo-Catalysts YVO4 and InVO4 Slab Systems with Water Molecules Adsorbed on the Surfaces
Authors: Oshikiri Mitsutake , Boero Mauro , Matsushita Akiyuki , Ye Jinhua 
Published: August 2010

AbstractElectronic structure properties of a photo-catalyst slab system based on a material YVO4 or InVO4 which is sandwiched by water molecular layers have been investigated by first-principles calculation. As a result, we found the tendency that the band gap of the InVO4 slab system sandwiched by water molecular layers was smaller than that of YVO4 system while the band gap values of the bulk crystals of YVO4 and InVO4 are almost same. This result may provide us a good clue to understand the reason why the InVO4 system can indicate a visible light response in photo-catalysis and the YVO4 system can not.
Morphologic, Compositional and Magnetic Characterization of Sputtered CoCr Thin Films for Applications in MTJs as Hard Spin Injectors
Authors: Martino Paola , Chiolerio Alessandro , Pandolfi Paolo , Tiberto Paola , Allia Paolo 
Published: August 2010

AbstractSpin-polarized currents across an insulating tunnel barrier, needed for the development of efficient magnetic tunneling junctions (MTJs), may be obtained using hard spin injector electrodes. Thin films of CoCr solid solutions have been fabricated involving two main steps: 1) deposition of Co/Cr alternated layers via RF magnetron sputtering both onto silicon (100) substrates and thermally oxidized wafers and 2) thermal annealing in a partial Ar pressure of 1 mTorr at 450°C for 1 hour and cooling treatment in a uniform magnetic field (600 Oe). The deposition of stacks of pure elements and subsequent diffusion treatment has been preferred instead of the direct deposition of the native alloy because in the former case the right composition and magnetic bias may be tuned more easily playing on the layer thicknesses and number of repetitions.A detailed numerical correlation of field effect SEM images and EDX micro-maps was used to evaluate the oxygen diffusion on the magnetic film, while an alternating gradient force magnetometer (AGFM) allowed us to evaluate at room temperature both coercivity and magnetic bias obtained after the field cooling treatment. The effect of standard thermal treatment on the homogeneity of the films is discussed, and a possible alternative heating technique is proposed.
Could Life Originate between Mica Sheets?: Mechanochemical Biomolecular Synthesis and the Origins of Life
Authors: Hansma Helen Greenwood 
Published: August 2010

AbstractThe materials properties of mica have surprising similarities to those of living systems. The mica hypothesis is that life could have originated between mica sheets, which provide stable compartments, mechanical energy for bond formation, and the isolation needed for Darwinian evolution. Mechanical energy is produced by the movement of mica sheets, in response to forces such as ocean currents or temperature changes. The energy of a carbon-carbon bond at room temperature is comparable to a mechanical force of 6 nanoNewtons (nN) moving a distance of 100 picometers. Mica's movements may have facilitated mechanochemistry, resulting in the synthesis of prebiotic organic molecules. Furthermore, mica's movements may have facilitated the earliest cell divisions, at a later stage of life's origins. Mica's movements, pressing on lipid vesicles containing proto-cellular macromolecules, might have facilitated the blebbing off of ‘daughter’ protocells. This blebbing-off process has been observed recently in wall-less L-form bacteria and is proposed to be a remnant of the earliest cell divisions (Leaver, et al. Nature457, 849 (2009).
Measuring Elastic Properties of Highly Metastatic Cells using Nano-Capillary Wrinkling
Authors: Iyer Nan , Cooper Katelyn , Yang Jianing , Zenhausern Frederic 
Published: August 2010

AbstractMeasuring elastic properties of cells has gained importance in the study of malignant transformations. The stiffness of a cell, which is technically referred to as the modulus of elasticity or Young's Modulus, E, is the measure of the amount of cell deformation caused by an applied known force. In vitro studies have shown that cancer cells have much lower elastic stiffness than normal cells. These stiffness measurements and their differences can be used to study the behavioral mechanics of how cancer cells grow, profligate, and die in a patient. Another important use of this difference in elasticity is in cancer detection.In this study, we explore the viability of measuring the elastic modulus of cancer cells by using a method that only requires the use of a low magnification microscope and a digital camera. In particular we are interested in applying the previously reported relationship between the wrinkling of thin films and the elastic properties of freely floating polystyrene (PS) films. Our work extends the scope of previous thin film studies by evaluating wrinkle formation in floating polystyrene films coated with biological cells. Our results show that the wrinkle formation is modified, both in morphology and in size, by the presence of a cellular monolayer on top of the PS film.
Sucker Rings from the Humboldt Squid Dosidicus gigas: The Role of Nanotubule Architecture on the Mechanical Properties
Authors: Miserez Ali , Weaver James , Kisailus David , Birkedal Henrik 
Published: August 2010

AbstractThe suckers that line the arms and tentacles of squid are equipped with rigid toothed ring-like elements that increase the gripping power during prey capture and handling. The sucker rings of the Humboldt squid Dosidicus gigas, are fully proteinaceous and contain nanotubules with diameters ranging from 100 to 250 nm. It has been shown previously that the ensuing porosity is a prime determinant of the local elastic modulus [A. Miserez et al., Adv. Mater. <b>21</b>, 401 (2009)]. Here additional nanoindentation data are presented together with structural analyses. The nanomechanical data support our model that the measured modulus is determined by the local porosity. The dry moduli reach ca. 8 GPa and are reduced about two-fold in the hydrated state. This surprisingly small reduction is discussed in relation to possible chemistries responsible for assembly of these structures.
Design of Nano-Composites for Ultra-High Strengths and Radiation Damage Tolerance
Authors: Misra Amit , Zhang X. , Demkowicz M. J. , Hoagland R. G. , Nastasi M. 
Published: August 2010

AbstractThe combination of high strength and high radiation damage tolerance in nanolaminate composites can be achieved when the individual layers in these composites are only a few nanometers thick and therefore these materials contain a large volume fraction associated with interfaces. These interfaces act both as obstacles to slip, as well as sinks for radiation-induced defects. The morphological and phase stabilities of these nano-composites under ion irradiation are explored as a function of layer thickness, temperature and interface structure. Using results on model systems such as Cu-Nb, we highlight the critical role of the atomic structure of the incoherent interfaces that exhibit multiple states with nearly degenerate energies in acting as sinks for radiation-induced point defects. Reduced radiation damage also leads to a reduction in the irradiation hardening, particularly at layer thickness of approximately 5 nm and below. The strategies for design of radiation-tolerant structural materials based on the knowledge gained from this work will be discussed.
Deposition of Ordered Arrays of Metal Sulfide Nanoparticles in Nanostructures Using Supercritical Carbon Dioxide
Authors: Wang Joanna , Smetana Alexander B. , Boeckl John J. , Brown Gail J. , Wai Chien M. 
Published: August 2010

AbstractSilver sulfide (Ag2S) and cadmium sulfide (CdS) nanoparticles of adjustable sizes are synthesized using a water-in-hexane microemulsion method and stabilized by dodecanethiol. The stabilized metal sulfide nanoparticles can be deposited homogenously on flat substrates forming ordered 2D arrays in supercritical fluid carbon dioxide (Sc-CO2). The use of Sc-CO2 leaves the particles unaffected by de-wetting effects and surface tension caused by traditional solvents and produces uniform arrays. The Sc-CO2 deposition technique can effectively fill the metal sulfide nanoparticles into nanoscale features, which is difficult to achieve by conventional solvent evaporation methods.
Effect of Sintering Atmosphere on the Microstructure of Gold Nanoparticulate Film
Authors: Jang Seonhee , Cho Hyejin , Kang Sungkoo , Choi Joonrak , Oh Sungil , Joung Jaewoo , Kim Donghoon 
Published: August 2010

AbstractOver the past few decades, metallic nanoparticles (NPs) have been of great interest due to their unique properties which distinguish them from those of bulk metals. Many attempts have been conducted to investigate the characteristics of NPs and their applications. However, the sintering process which converts metallic NPs to conductive film was not established yet. In this study, the microstructure evolution of Au NPs after sintering under different thermal condition was examined and the film quality was studied based on densification, organic residues and electrical resistivity. Au NP ink dispersed in a toluene were spin coated on Ni-plated FCCL or Si substrates and thermally treated in a furnace under different sintering profiles under various types of flows such as air, nitrogen (N2), or reducing atmosphere of formic acid (FA). The Au ink was consisted of Au NPs coated with an organic capping molecule. The capping molecules not only help NPs to disperse but prevent aggregation and precipitation of NPs out of solution. When the NPs are treated by thermal process, the surface ligands from capping molecule start to decompose and necking and melting of NPs occur producing the film with the electrical conductivity. The diameter of Au NPs was approximately between 5-7 nm with spherical shape. The Au film sintered under air showed only necking between neighboring Au NPs without further grain growth. When Au NPs films were sintered under N2 atmosphere, NPs fused together in clusters. Under sintering with flows of FA, a larger area of pores due to the volume shrinkage of the film was observed since an agglomeration and melting of NPs were considerably progressed compared to the film sintered under N2. Sintering with a flow of a single gas such as air or N2 showed organic residues in the film indicated by C-H or C-O stretch peaks. However, when mixed flows of FA and N2 were applied, there was no IR peaks from organic substances observed in the film. It is assumed that the organic capping molecules surrounding the Au NPs were removed significantly with sintering with two flows of FA and N2. The microstructure showed less pore distribution and lower level of organic residues compared to those sintered under air, N2, or FA atmospheres. The electrical resistivity was about twice of bulk value of 2.44 μΩ -cm. Overall Au NPs film sintered under FA and N2 resulted in a better sintering effect based on densification of the film and level of residual organics, translating into a relatively high electrical conductivity.
Three-dimensional Organic Field-effect Transistors on Plastic Substrates: Flexible Transistors with Very High Output Current
Authors: Takeya Jun , Uno M. , Nakayama Kengo 
Published: August 2010

AbstractAttractiveness of organic field-effect transistors are in their low-cost and easy fabrication processes as well as their mechanical flexibility, while a significant drawback has been their poorer transistor performances than those of silicon and oxide semiconductors because of lower carrier mobility in organic semiconductors. We have developed an easy MEMS-based process to fabricate three-dimensional organic transistors with metal-insulator-semiconductor structures of multiple vertical channels on plastic platforms. The design maximizes the space availability and the output current per area. The flexible three-dimensional organic transistors indeed present outstanding current of ∼ 0.5 A/cm2, which is more than sufficient for driving pixels of typical organic light-emitting diodes. High on-off ratio up to 107 is also demonstrated.
Leakage Current Reduction and Ferroelectric Property of BiFe1-xCoxO3 Thin Films Prepared by Chemical Solution Deposition Using Rapid Thermal Annealing
Authors: Nguyen TruongTho , Kanashima Takeshi , Okuyama Masanori 
Published: August 2010

AbstractFerroelectric Bi1.1Fe0.9Co0.1O3 (BFCO) thin films were prepared on Pt/TiO2/SiO2/Si substrates by chemical solution deposition method using rapid thermal annealing (RTA). The thickness of all BFCO thin films is about 100 nm. Although the BFCO prepared at 545°C has a large value of difference of polarization at zero field, 88 C/cm2, the P-E hysteresis loop of the BFCO thin film prepared at 520°C looks like more saturated and shows 47 C/cm2 of difference of polarization at zero field in the applied electric field of 2 MV/cm. The leakage current of the BFCO film annealed at 520°C, is about 2 × 10-2 A/cm2 at room temperature (RT). Moreover, it is also shown that the saturated possibility of P-E hysteresis loops and in 2 MV/cm their apparent difference of polarization at zero field depend on not only the leakage current but also scanning frequency used to measure BFCO thin films. Accordingly, the P-E hysteresis loops of BFCO thin films prepared from 520°C to 545°C seem to be saturated at high frequency from 10 KHz to 20 KHz when these samples are measured at RT.
Isothermal Martensitic Transformation Kinetics in Ni-Mn-Sn Ferromagnetic Shape Memory Alloys
Authors: Shamberger Patrick , Pakhomov Alexandre , Ohuchi Fumio 
Published: August 2010

AbstractThis study examines the kinetics of the martensitic phase transformation in a representative Ni-Mn-Sn Heusler alloy. Here, we present data on isothermal and continuous cooling/warming transformations in both bulk polycrystalline and individual small particle samples. We demonstrate that while the martensite to austenite transformation proceeds very rapidly (faster than the time-scale of our observations), the austenite to martensite transformation has a significant isothermal component. A similar asymmetry is also noted in transformation behavior of individual martensite plates. We conclude that the observed time dependence is due primarily to nucleation-limited kinetics.
Polyoctenamer - Single Walled Carbon Nanotube Composites: Spectroscopic Investigations
Authors: Chipara Alin Cristian , Mion Thomas , Villegas Rafael , Lozano Karen , Chipara Dorina Magdalena , Tidrow Steven C. , Chipara Mircea 
Published: August 2010

AbstractComposites of single walled carbon nanotube dispersed within polymeric matrices have been investigated by spectroscopic techniques (Raman and Wide Angle X-Ray Spectroscopy). Raman investigations included an in depth analysis of the radial breathing mode (for single wall carbon nanotubes) and a brief analysis of the lines originating from the polymeric matrix. Raman spectra were successfully simulated by computer assuming that the as recorded spectrum is a convolution of lines whose line shape is well described by a modified Breit-Wigner-Fano equation. The dependence of the position of the lines belonging to the radial breathing mode on the concentration of single walled carbon nanotube has been investigated, with emphasis on information pertinent to the stress transfer from the macromolecular matrix to the filler and to the coating of single walled carbon nanotube by polymeric chains. Complementary Wide Angle X-Ray Spectroscopy measurements provided information about the effect of the loading with single walled carbon nanotube on the crystal structure of the polymeric matrix. The research aims to a better understanding of the interactions between polymeric matrices and nanofillers.
The Effect of Carbon Nanotube Surface Energy on the Adhesion of Macrophages
Authors: Chun Young Wook , Webster Thomas J. 
Published: August 2010

AbstractPurified carbon nanotubes (with removed toxic catalytic particles) have been considered as novel materials for drug delivery and for generating artificial organs more efficiently than traditional tissue engineering materials due to their unique surface features. The surface chemistry of carbon nanotubes has been modified through various functionalization strategies to increase biocompatibility. Importantly, modulating the intrinsic material surface energy of carbon nanotubes (without functionalization, thus, establishing permanent, non degradable chemical, and physical surface properties) can potentially reduce an immune response mediated by macrophages. Herein, we report macrophage responses on different surface energy carbon nanotubes while keeping their nanoscale surface roughness. Specifically, interactions of ultra hydrophobic (bare or unmodified) and hydrophilic carbon nanotubes (due to the formation of oxide layers) with macrophages were investigated. It was observed that macrophage density on both carbon nanotube scaffolds were lower than on traditional materials. In particular, the amount of released cytokine (TNF-α) from macrophages cultured on hydrophilic carbon nanotube scaffolds was much smaller than on hydrophobic carbon nanotube scaffolds. All results clearly supported that tailoring the surface energy of carbon nanotubes mediates a macrophage immune response.
Generation and Capture of CO2and CO in Graphite Oxide Stacks during Thermal Reduction
Authors: Acik Muge , Guzman Rodolfo , Chabal Yves J 
Published: August 2010

AbstractInfrared spectroscopy is used to monitor the evolution of CO2(2330-2350 cm-1) and CO (2050-2200 cm-1) generated during thermal reduction of graphite oxide. The appearance of CO2at low temperatures (≤200°C) is associated with oxygen removal in species such as anhydrides, esters, lactols, carboxylic acids and lactones either at the edges or in the distorted basal plane of the GO sheets. At higher temperatures (250°C-750°C), release of CO is observed and may be due to decomposition of CO2or oxygen-containing species like ethers, carbonyls, phenols or quinones. Observation of these gases is possible in multilayer GO because they are trapped in between the interlayer spacing of GO stacks for a time sufficient for detection.
Amino Terminated Polyethylene Glycol Functionalized Graphene and Its Water Solubility
Authors: Hou Shifeng , Cuellari Robert D. , Hakimi Najeeb Hoshang H. , Patel Krutika , Shah Pratik , Gorring Matthew , Brachfeld Stefanie 
Published: August 2010

AbstractA chemical modification process was developed to functionalize graphene with specific groups. Graphene oxide (GO) was successfully functionalized with thionyl bromide which can be used as precursors for further functionalization. Amino terminated-polyethylene glycol (PEG-NH2) molecules were linked to single-layer graphene sheets through covalent bond. FT-IR, SEM and UV-vis spectroscopy techniques were used to characterize PEG modified graphene oxide and PEG modified reduced graphene oxide (PEG-RG). PEG-RG could disperse in water, tetrahydrofuran and ethylene glycol, with individual, single-layer graphene sheets spontaneously. The dispersion behavior of PEG-RG in an aqueous solvent has been investigated. A series of solutions of PEG-RG with concentrations of 0.001% to 1.5% were prepared and the PEG-RG dispersions exhibited long-term stability. In addition, a PEG-RG film with layered structure and high conductivity has been successfully prepared by filtration.
Suppression of Edge Recombination in InAs/InGaAs DWELL Solar Cells
Authors: Gu Tingyi , El-Emawy Mohamed A , Yang Kai , Atintz Andreas , Lester Luke F 
Published: August 2010

AbstractThe InAs/InGaAs DWELL solar cell grown by MBE is a standard pin diode structure with six layers of InAs QDs embedded in InGaAs quantum wells placed within a 200-nm intrinsic GaAs region. The GaAs control wafer consists of the same pin configuration but without the DWELL structure. The typical DWELL solar cell exhibits higher short current density while maintaining nearly the same open-circuit voltage for different scales, and the advantage of higher short current density is more obvious in the smaller cells. In contrast, the smaller size cells, which have a higher perimeter to area ratio, make edge recombination current dominant in the GaAs control cells, and thus their open circuit voltage and efficiency severely degrade. The open-circuit voltage and efficiency under AM1.5G of the GaAs control cell decrease from 0.914V and 8.85% to 0.834V and 7.41%, respectively, as the size shrinks from 5*5mm2 to 2*2mm2, compared to the increase from 0.665V and 7.04% to 0.675V and 8.17%, respectively, in the DWELL solar cells.
The lower open-circuit voltage in the smaller GaAs control cells is caused by strong Shockley-Read-Hall (SRH) recombination on the perimeter, which leads to a shoulder in the semi-logarithmic dark IV curve. However, despite the fact that the DWELL and GaAs control cells were processed simultaneously, the shoulders on the dark IV curve disappear in all the DWELL cells over the whole processed wafer. As has been discussed in previous research on transport in QDs, it is believed that the DWELL cells inhibit lateral diffusion current and thus edge recombination by collection first in the InGaAs quantum well and then trapping in the embedded InAs dots. This conclusion is further supported by the almost constant current densities of the different area DWELL devices as a function of voltage.