bluuebunny/crossref_metadata_2025_split huggingface dataset:
Interfacial Force Microscopy and its Application in Metal Matrix Composites
Authors: Liebig Berthold E. , Chantis Athanasios , Steffan Craig E. , Puszynski Jan A. , Winter Robb M. 
Published: April 2011

AbstractMetal matrix composites (MMCs) combine the properties of metal and ceramic or intermetallic materials. Common examples of metal matrix composites are Cu-Al2O3, SiCw-Al, Al-Al2O3, Al-B4C, and Ni-NiAl3. Mechanical or thermal properties, such as strain-stress behavior, or thermal expansion coefficient can be tailored by changing the content of the reinforcing phase. The most common techniques of measuring mechanical properties of composite materials rely on macroscopic approach. During the past fifteen years, a significant effort has been made to develop various techniques of measuring mechanical properties on a microscopic level. These techniques include atomic force microscope (AFM) and depth sensing indentation techniques, based on Hertzian contact mechanics. However, it is still a challenge to measure reliably and quantitatively the Young's modulus and Poisson's ratio of individual phases as well as properties at the interfaces. This presentation will focus on fundamental aspects of measuring of mechanical properties of metal matrix composites at nano-scale using Interfacial Force Microscopy (IFM). The IFM is a scanning probe microscope, which utilizes a unique self-balancing capacitance force sensor. Force-displacement curves obtained with the IFM are analyzed using Hertzian contact mechanics to extract the Young's moduli of the individual phases and interface region with high spatial resolution. The properties of Cu-Al2O3, Al-SiCp composites will be discussed in detail. Furthermore, a comparison of experimental data with mechanical properties calculated from first principles will be discussed.
A Nanoscratch Method for Assessing Wear of Metal Carbide-Metal Nacreous Nanostructures
Authors: Obbard Rachel W. , Gross Todd S. 
Published: April 2011

AbstractThe wear resistance of metal carbide-metal nacreous nanostructures is compared to that of a solid metal carbide hard coating. A reciprocating nanoscratch method has been developed which allows the assessment of wear resistance of the film independent of substrate type or film-substrate adhesion. A series of nominally 1 micron thick TiC-based multilayer films on Si substrates were produced using RF magnetron sputtering. A scratch protocol consisting of 70 reciprocal scratches each 9.5 m m in length was applied. Data reduction techniques were used to remove the effects of sample tilt and drift. The resulting normal displacement as a function of scratch cycles is used to compare the wear of different films on Si <111> substrates. Specific wear characteristics related to film morphology are examined. This investigation showed that this nanoscratch technique holds promise as a thin film wear characterization technique.
Effect of Co Seed Layers on the Magnetic Anisotropy of Au/Co Metallic Multilayers
Authors: Kamiko Masao , Mizuno Hiroyuki , Lu Guang-Hong , Zhou Yao-Min , Yamamoto Ryoichi 
Published: April 2011

AbstractAu/Co(111) multilayers and a Au buffer layer were grown by MBE on Al2O3(0001) substrates using a thin Co seed layer. The influence of the Co layer on the structure of the Au/Co multilayers was studied by X-ray diffraction and reflection high-energy electron diffraction (RHEED), and compared to its effect on the magnetic anisotropy. The Au buffer layer grown on Al2O3(0001) substrates display a large fraction of (111) fiber texture, giving rise to a lack of lateral continuity in the film. The initial deposition of a few monolayers of Co onto Al2O3(0001) substrates prior to deposition of the Au buffer layer yielded (111) epitaxial films with no texture. The use of this seeded epitaxy results in a highly improved structural quality of Au/Co(111) multilayers. From the results of Low-angle X-ray diffraction and RHEED observations, we confirmed that the interfaces of Au/Co multilayers with Co seed layer are sharper than those without Co seed layer. It cleary shows that the use of Co seed layer improved the periodicity of Au/Co multilayers. The magnetic anisotropy energy of Au/Co multilayers increased by using the Co seed layer, and the high quality of structure results larger perpendicular magnetic anisotropy.
Chemically Amplified Resist Approaches for E-beam Lithography Mask Fabrication
Authors: Maldonado J.R. , Angelopoulos M. , Huang W. , Brainard R. L. , Guevremont J. M. , Tan Z. 
Published: April 2011

AbstractThis paper describes stable, high sensitivity (5-10 μC/cm2 at 50 kV) e-beam resist systems utilizing chemical amplification suitable for mask fabrication for device generations below 100 nm. In particular, two resist systems with improved performance for mask fabrication developed in a joint program by Etec, IBM and Shipley will be described: a Si- doped version of the IBM KRS-XE resist (now commercially available) developed at IBM Research, and a new MANA resist developed at Shipley. Commercialization issues for mask e-beam resists also will be discussed.
Charge Transport in Mesoscopic Carbon Network Structures
Authors: Ksenevich V. , Galibert J. , Samuilov V. , Seo Y.-S. , Sokolov J. , Rafailovich M. 
Published: April 2011

AbstractThe charge transport and quantum interference effects in low-dimensional mesoscopic carbon networks prepared using self-assembling were investigated. The mechanism of conduction in low-dimensional carbon networks was found to depend on the annealing temperature of the nitrocellulose precursor. The charge transport mechanism for carbon networks obtained at Tann=750 0C was found to be the hopping conductivity in the entire investigated temperature range. The Coulomb gap near the Fermi level in the density of states was observed in the investigated carbon networks. The width of the Coulomb gap was found to be decreased with the annealing temperature of the carbon structures. The crossover from the strong localization to the weak localization regime of the charge transport in the carbon structures, obtained at Tann=950 0C and Tann=1150 0C, was observed in the temperature range T>100 K and T>20 K, respectively.
Nanoscale Control of the Polymer-Fullerene Interface in Photovoltaic Devices by Thermally-Controlled Interdiffusion
Authors: Drees M. , Davis R.M. , Marciu D. , Premaratne K. , Graupner W. , Miller M. , Heflin J.R. 
Published: April 2011

ABSTRACTUltrafast photoinduced charge transfer from conjugated polymers to fullerenes has led to extensive studies of these systems as photovoltaic devices. The charge transfer process prevents radiative electron-hole recombination, resulting in free, mobile charges. A limiting factor is the exciton diffusion distance, which is of the order of 10 nm. If the fullerene is not within this distance of the optical excitation site, no charge separation will take place. The simplest system for such devices is a bilayer system in which a film of C60 is sublimed onto a spin-cast film of MEH-PPV, for example. We describe studies in which the polymer is heated above the glass transition temperature in an inert environment, inducing an interdiffusion of the polymer and the fullerene layers. With this process, a controlled, bulk, gradient heterojunction is created. The photoluminescence and the short circuit currents of the devices show a dramatic decrease in photoluminescence and concomitant increase in short circuit currents, demonstrating the improved interface.
Optimal Morphology for a Composite Solar Cell
Authors: Burlakov V. M. , Briggs G. A. D. , Sutton A. P. 
Published: April 2011

ABSTRACTCharge transport in a composite solar cell (CSC) is analysed by considering independent and random migration of the photo-generated electrons/holes over interpenetrating conducting networks. It is shown that besides an interface area and the materials parameters the efficiency (average number of the carriers reaching the electrode per time unit) of the CSC depends on the effective dimensionality of the conducting channels. Our analysis shows that the 1-d network is ∼20% more effective than the 3-d one, and therefore the morphology of the 1-d type for the organic phase within a 3-d inorganic one is preferable for the CSC. It is shown that the CSC with bulk generation of excitons is potentially more efficient than a dye-sensitised solar cell. The highest efficiency of collection of photo-generated carriers for the CSC at highest possible current for the given material properties cannot exceed ∼40% and 34% for 1-d and 3-d networks respectively.
Photoelectric Cells of Merocyanine Langmuir-Blodgett Films Utilizing Surface Plasmon Excitations
Authors: Kato Keizo , Takahashi Futoshi , Shinbo Kazunari , Kaneko Futao , Wakamatsu Takashi 
Published: April 2011

ABSTRACTShort-circuit photocurrents (ISC) due to surface plasmon (SP) excitations have been investigated for the photoelectric cells using Langmuir-Blodgett (LB) films of merocyanine (MC) dye. The MC dye exhibits p-type conduction, and the Schottky and Ohmic contacts are obtained at the interfaces between MC LB films and Al thin films and between MC LB films and Ag thin films, respectively. Since the Schottky diodes show the photoelectric effects, the Schottky photoelectric cells have been constructed. The cells with two kinds of structures, that is, prism/Al/MC/Ag (type I) and prism/MgF2/Al/MC/Ag (type II), have been prepared. In the attenuated total reflection (ATR) method, the types I and II have the Kretschmann and both the Kretschmann and Otto configurations, respectively. SP has been resonantly excited at the interface between Ag and air for the type I and at the interfaces between MgF2 and Al between Ag and air for the type II. The ATR and the ISC properties have been simultaneously measured as a function of the incident angles of the laser beams. The peaks of the ISC have corresponded to the resonant angles of the ATR curves. The electric fields and optical absorptions in the cells have been also calculated using the dielectric constants and the film thicknesses obtained from the ATR measurements. The calculated absorptions in the MC layers as a function of the incident angles have corresponded to the results of ISC. It has been estimated that the ISC for both types I and II could be enhanced by the excitations of SP in the ATR configurations.
A Novel Conformational Searching Technique applied to small polymer units of 3-phenyl-1-ureidonitrile
Authors: Silver Ari , Sohlberg Karl 
Published: April 2011

ABSTRACTA novel conformational searching scheme is employed to identify low energy structures for low-degree polymers of 3-phenyl-1-ureidonitrile, a proposed thin film data storage material. Vibrational analysis of the predicted polymer structures is consistent with experimental reports and supports the experimentally proposed polymerization mechanism.
Photosensitized Reaction of Poly(L-lactic Acid) via Two-Photon Ionization of Dopant
Authors: Sakai Wataru , Wakabayashi Kosuke , Nishinaka Hiroshi , Kawamoto Hiroki , Kinoshita Motoi , Tsutsumi Naoto 
Published: April 2011

ABSTRACTWe here studied photosensitized radical reaction of poly(L-lactic acid) (PLA) using spectrophotometry, electron spin resonance (ESR), gel permeation chromatography (GPC) measurements, and semiempirical molecular orbital calculation. PLA doped with N,N,N',N'-tetramethyl-p-phenylenediamine (TMPD) was irradiated at 77 K using UV light. After the irradiation, we observed a new broad absorption band that is assigned to TMPD radical cation produced by two-photon ionization. ESR spectrum of the irradiated sample also indicated presence of main chain scission radical of PLA as well as the TMPD radical cation. By increasing the irradiation time, the ESR spectrum changed by another radical species which is produced by dehydrogenation of PLA main chain. Spectral simulation for the obtained ESR spectra revealed changes of relative amounts. The GPC measurements clearly indicated decrease in molecular weight of PLA after the irradiation. The semiempirical molecular orbital calculation was used to confirm the reaction scheme of radical anion decomposition.
Iodine Release from Silver Iodide under Reducing Condition with Iron-Bearing Minerals
Authors: Xia X. , Inagaki Y. , Hattori A. , Idemitsu K. , Arima T. 
Published: April 2011

ABSTRACTIodine release from silver iodide (AgI) to water was evaluated under reducing conditions in the presence of iron-bearing minerals, goethite (FeOOH), magnetite (Fe3O4) and Wüstite (FeO). The release tests were performed in a glove box purged with gas mixture (Ar+5%H2), and the concentrations of dissolved iodine, silver and iron were measured. The apparent equilibrium concentration of dissolved iodine was 4.0 ×10−8, 4.3×10−8 mol/l for the tests with FeOOH and Fe3O4, respectively. The values were almost the same as in the test without minerals. For the test with FeO, the concentration of dissolved iodine was 5.4×10−3 mol/l, which is five orders of magnitude higher than for the other tests. Solid phase analyses by using XRD and SEM/EDS indicated that metallic silver precipitated on the surface of the original AgI for the test with FeO and on the surface of Fe3O4 for the test with Fe3O4, but not for that with FeOOH. These results showed that only FeO could reduce AgI effectively to increase iodine release. The amount of dissolved Fe(II) was a key factor affecting AgI reduction instead of redox potential of solution. Kinetic processes may also play an important role in AgI reduction and associated iodine release under reducing condition.
Diogenic Transmutation Effects in a Crystalline Aluminosilicate Ceramic: a Tem Study
Authors: Fortner Jeffrey , Aase Scott , Reed Don 
Published: April 2011

ABSTRACTWe demonstrate the use of transmission electron microscopy (TEM) to study the effects of beta-decay of radioactive 137Cs to 137Ba in crystalline pollucite (CsAlSi2O6). Most prior work on radiation effects in materials has focused on structural damage from alpha radiation. Beta radiation, on the other hand, causes little atomic displacement, but the decay transmutation, that is, the radioactive decay of a radioisotope to an isotope of another element, results in progeny with different the valence and ionic radius. Cesium-137, a fission product of uranium, is a major contaminant at U.S. Department of Energy production facilities. Pollucite is an aluminosilicate ceramic with potential use for long-term storage of 137Cs. We focused on one of several available 137Cs sources originally fabricated in the 1970s and 1980s. These sources were small, sealed, stainless steel capsules containing pollucite in which varying amounts of the natural Cs had been replaced by radioactive 137Cs (t1/2 = 30.13 years). The sample chosen for TEM examination, aged for nearly 20 years, contained the most radiogenic barium and was expected to show the largest radiation effects. Bright field transmission images revealed a homogeneous crystalline matrix, with no evidence of distinct Ba phases or ex-solution phenomena resulting from the 137Cs transmutation. Electron diffraction patterns obtained from several portions of the sample were consistent with literature values for pollucite. These data suggest that little substantial damage was done to the crystal structure of this sample, despite the transmutation of nearly 1.5% of the total cesium to barium over the elapsed 20 years. Although our observations are limited, to our knowledge these are the only available data in which transmutation effects have been isolated from other radiation damage phenomena.
Influence of Salinity on The Hydraulic Conductivity of Compacted Bentonite
Authors: Cho Won-Jin , Lee Jae-Owan , Kang Chul-Hyung 
Published: April 2011

ABSTRACTThe effect of salinity on hydraulic conductivities of compacted bentonites with various dry densities was studied. The hydraulic conductivities increase with increasing salinity only when the dry density of bentonite is relatively low. The degree of increase becomes more remarkable at a lower dry density of bentonite. For bentonites with densities of 1.0 Mg/m3 and 1.2 Mg/m3, the hydraulic conductivities associated with the 0.4 M NaCl solution increase beyond those associated with the fresh water solution by factor of 7 and 3 times, respectively. However, for the bentonite with dry density higher than 1.4 Mg/m3, the salinity has an insignificant effect on the hydraulic conductivities, and the hydraulic conductivity is nearly constant within the salinity range of 0 to 0.4 M NaCl.
Element Partitioning in a Pyrochlore-Based Ceramic Nuclear Waste form
Authors: Gieré R. , Hatcher C. , Reusser E. , Buck E. C. 
Published: April 2011

ABSTRACTPyrochlore-rich ceramics containing additional zirconolite, brannerite and rutile have been developed for immobilizing excess weapons plutonium. This study reports data for a ceramic containing small amounts of Al and Mo in addition to the major oxide components of Ti, U, Ca, Hf, Gd and Ce. Hafnium and Gd are added as neutron absorbers, Al and Mo represent impurities. Quantitative electron microprobe data demonstrate that UO2 is strongly partitioned into brannerite (45 wt%), which is present as euhedral crystals with inclusions of unreacted UO2. Pyrochlore forms the groundmass and has an average UO2 content of 28 wt%. Zirconolite contains only 15 wt% UO2, but is significantly more effective in accommodating Hf and Gd than both brannerite and pyrochlore. Zirconolite incorporates U together with Hf and Ce in one structural site, whereas brannerite and pyrochlore accommodate U with Gd in a site that is distinct from that occupied by Hf. Incorporation of Gd into zirconolite takes place via a coupled substitution involving Al, thus explaining the high Al2O3 contents (3 wt%). Molybdenum was not detected in the major oxides, and it might be present in the accessory rutile. Although the studied waste form was designed to incorporate Pu, the present dataset is also valuable because immobilization of highly fissile U (e.g., U-233) might need to be considered in the future.
An Overview of the H12 Performance Assessment in Perspective
Authors: Miyahara Kaname , Makino Hitoshi , Kato Tomoko , Wakasugi Keiichiro , Sawada Atsushi , Ijiri Yuji , Takasu Aki , Naito Morimasa , Umeki Hiroyuki 
Published: April 2011

ABSTRACTThe H12 performance assessment (PA) provided a test for the robustness of a HLW repository system concept based on structured siting and design, taking account of a wide range of potentially suitable Japanese geological environments. The generic nature of the host rock in the H12 assessment means, however, that emphasis is placed verymuch on strong EBS performance. The assessment included a comprehensive evaluation of uncertainty and potentially detrimental factors, including perturbations due to external events and processes. Despite the considerable uncertainty at the current stage of the Japanese program, a safety case that is adequate for the aims of the assessment can be made by a strategy of employing conservatism where there is uncertainty and stressing the reliability and effectiveness of the performance of the near-field. The aim of this paper is to present the H12 PA in a way which makes the PA process clearer and the implications of the results more meaningful, both to workers within the PA field and to a wider technical audience.
Determination of liquid-solid partition coefficients (Kd) of radionuclide anionic species from a contaminated aquifer
Authors: Carona François , Haas Michael K. , Cooper Edward L. , Robertson David E. 
Published: April 2011

ABSTRACTContaminated groundwater from a former liquid waste discharge area at the Chalk River Laboratories was treated with ion exchange resins to isolate aqueous extracts of selected radionuclides (60Co, 106Ru, 137Cs, 238Pu, 239/240Pu, 241Am and 244Cm). The extracts were then mixed with native uncontaminated soil material to determine their liquid-solid partitioning coefficients (Kd). Separate Kd values of the same elements were also obtained with the usual short-term “batch” technique for comparison, but using different radioisotopes as tracers (57Co and 134Cs), spiked to the extracts. The comparison included separate Kd determinations with 239/240Pu and 241Am as tracers, added to uncontaminated groundwater.In all cases, the radionuclides originally present in the contaminated groundwater extracts exhibited low Kd values, compared to the values obtained in the “batch” method with tracers (57Co, 134Cs, 239/240Pu and 241Am). The difference was up to two orders of magnitude. This was attributed to differences in aqueous speciation of the nuclides in the contaminated groundwater, allowing limited interactions of complexed radionuclide species with soil material. Our results indicated that all the radionuclides were predominantly in anionic form in the groundwater, whereas in the tracer “batch” experiment, 57Co and 134Cs were predominantly cationic, Pu and Am were predominantly anionic. Hydrolysis partially explains the dominant anionic character of Am and Pu in the tracer experiments, however dissolved organics are suspected to dominate the speciation of the radionuclides in contaminated groundwater. Our experiment implies that in some cases, if Kd values obtained using the “batch” method with tracers are used in transport models, radionuclide transport could be underestimated.
Fabrication of Stimulus-Responsive Polymeric Nanostructures by Proximal Probes
Authors: Ahn Sang-Jung , Lee Woo-Kjung , Zauscher Stefan 
Published: April 2011

ABSTRACTThe triggered control of interfacial properties on the nanometer scale holds significant promise for actuation in bio-nanotechnology applications where polymeric actuators may manipulate the transport, separation, and detection of biomolecules. To fabricate patterned, stimulus-responsive polymer brushes we have developed several methods that combine surface initiated polymerization (SIP) with dip-pen nanolithography (DPN). Surface-confined, stimulus-responsive polymer brush nanopatterns were fabricated by amplification of DPN patterned, self-assembled monolayers of 16-mercaptohexadecanoic acid on gold surfaces by SIP of N-isopropylacrylamide (NIPAAm). While free radical polymerization yielded only short polymer brushes (DP<50), atom transfer free radical polymerization (ATRP) produced thick, uniform polymer brushes. For free radical polymerization the thickness of the polymer brush layer is a function of the lateral feature size and the initiator density and is maximal at pattern boundaries.
Biotemplate Directed 2-Dimensional Nanostructure Assembly
Authors: Yu Seungju M. , Mo Xiao , Krebs Mark P. 
Published: April 2011

ABSTRACTThere are manifest scientific and technological interests in organizing nanocrystals (NC) into controlled architectures and work is rapidly expanding in exploiting opportunities through bio-assembly processes. In this research, we have applied biologically assembled nano-scale template to direct formation of precisely defined 2D nanocrystal arrays. We explored purple membrane (PM), a naturally occurring membrane protein (bacteriorhodopsin, BR) crystal patch from halobacteria, as a precisely structured nanometer-scale template. We have developed genetically engineered PMs that display unique functional group (cystein) on the membrane surfaces with precisely defined nano-scale symmetry. These reactive functional groups were used as specific anchoring sites for NC immobilization. We show that the cystein mutants of BR mutated at the surface of the PM are capable of forming stable PM-like hexagonal crystal lattices in the host cell membrane. These crystal patches are easily purified by ultracentrifugation and can be used to react with functionallized gold nanoclusters. We also present the variation of crystal lattice by detergent treatment and recrystallization techniques. The PM has been known to posses good materials properties and is expected to allow formation of robust nanocrystal array that can withstand variety of optical and electrical characterization conditions.