bluuebunny/crossref_metadata_2025_split huggingface dataset:
Interaction of Hydrogen Peroxide With Carbon Steel and Magnetite
Authors: Gimenez Javier , Casas Ignasi , Sureda Rosa , Pablo Joan de 
Published: April 2011

AbstractHydrogen peroxide is considered as one of the main oxidants formed due to the radiolysis of water. In a spent nuclear fuel repository, it is necessary to establish the interaction of hydrogen peroxide with the elements constituting the repository. The objective of this work is to study the consumption of hydrogen peroxide via reaction with the elements of the canister.In this sense, two different series of experiments were conducted, with iron steel an magnetite, respectively. Each series consisted on three different experiments that contained a coupon of the solid and different hydrogen peroxide concentrations (10−4 mol·dm−3, 10−5 mol·dm−3 and 10−6 mol·dm−3). Hydrogen concentration in solution was measured at different intervals of time by means of chemiluminescence. At the end of the experiments, the coupons were studied by X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) in order to determine the possible secondary solid phases formed on the coupons.In both series of experiments, a decrease of the hydrogen peroxide concentration in solution with time was observed. The determined consumption rates increased with hydrogen peroxide concentration and were higher in steel than in magnetite. The reaction orders relative to hydrogen peroxide concentration were very close to the unity on both solids.The study of the carbon steel coupons by SEM at the end of the experiments showed that they were more attacked at higher hydrogen peroxide concentrations. On the other hand, the XRD measurements in the steel coupons showed that lepidocrocite (γ-FeO(OH)), and magnetite (Fe3O4) were formed on the coupon as iron secondary solid phases.
Effect of magnetism on precipitation of Cu in bcc Fe: Ab-initio based modeling
Authors: Gorbatov O.I. , Ruban A.V. , Korzhavyi P.A. , Gornostyrev Yu.N. 
Published: April 2011

AbstractTheoretical modeling of the decomposition in bcc Fe-Cu alloys has been performed using a combined approach which includes ab-initio calculations of the effective cluster interactions and statistical-mechanical (Monte Carlo) simulations. We showed that the effective Cu-Cu and Cu-vacancy interactions in the bcc Fe matrix have a strong dependence on the global magnetic state of iron. As a result, all the related thermodynamic properties of the alloys (such as solubility limit and diffusivity) are expected to have a pronounced non-Arrhenius temperature behavior, originated from variation of the global magnetization with temperature. We find that strong Cu-vacancy interactions in the bcc Fe matrix lead to a remarkable effect of vacancies on the Cu precipitation and significantly modify the alloy decomposition kinetics under irradiation.
Effect of HBS Structure in Fast Release Fraction of 48 GWd/tU PWR Fuel
Authors: Pablo J. de , Serrano-Purroy D. , Gonzalez-Robles E. , Clarens F. , Martinez-Esparza A. , Wegen D.H. , Casas I. , Christiansen B. , Glatz J.-P. , Gimenez J. 
Published: April 2011

AbstractTwo important issues in Performance Assessment exercises regarding the alteration of Spent Nuclear Fuel (SNF) are the contribution of Instant or better called Fast release Fraction (FRF) and the effect of High Burn-Up Structure (HBS). Therefore this paper focuses on the effect of HBS in FRF of a PWR irradiated in a commercial reactor with a mean Burn-Up (BU) of 48 GWd/tU. Additionally, determined FRF are compared with previous experiments performed with PWR with a mean BU of 60 GWd/tU, in order to evaluate the effect of BU on FRF.In order to study the HBS contribution, static leaching experiments are performed with two samples prepared from different radial positions, labeled Core, central region and Out, enriched with HBS. Two synthetic leaching solutions, bicarbonate and bentonitic granitic groundwater are used under oxic conditions.The estimated FRF are calculated from the determined Fraction of Inventory in Aqueous Phase (FIAP) taking into account the inventory determined experimentally for each fraction.Higher release is observed for Core sample, which can be an indicative that HBS does not increase the RN release. With the exception of Rb and Cs, which release is higher at lower BU, no clear effect of BU is observed within the studied range.
Rim Instant Release Radionuclide Inventory From French High Burnup Spent UOX Fuel
Authors: Roudil D. , Jegou C. , Broudic V. , Tribet M. 
Published: April 2011

AbstractTo assess the long-term behavior of spent fuel in a nuclear waste repository, the chemical reactions between the fuel and possible intruding water must be understood and the resulting radionuclide release must be quantified. The instant release fraction (IRF) source term assumed to be instantaneously accessible to water after the failure of the waste container. Some IRF values for different kinds of spent fuel are available in the literature. However, the possible contribution the rim restructured zone for high-burnup UOX fuels, was not necessary taken into account. A specific study of the leaching behavior of the rim zone has been carried out on a UOX fuel sample with a burnup of 60 GWd·t-1 and 2.8% FGR. The 134/137Cs and 90Sr rim IRF are effectively higher than the gap and grain boundary inventories (respectively 4.4 wt% and 0.3 wt% of the total Cs and Sr inventories). Nevertheless because of the relative small volume of this zone in the pellet, the impact of the rim inventory appears to be limited and the complete Cs and Sr IRF (gap, grain boundaries and rim), were estimated at 1.85 and 0.3 wt%, respectively
Supporting Development of Practical Designs for a Japanese HLW Repository
Authors: Makino Hitoshi , Umeki Hiroyuki , Ochi Yasuhiro , Hioki Kazumasa , Okubo Hiroo , Matsumoto Masaaki , Sato Osamu , Masuda Sumio , McKinley Ian G. 
Published: April 2011

AbstractIn preparation for actual repository implementation, designs that could be tailored to specific sites need to be considered. This requires a paradigm shift in design philosophy, moving away from a single reference design towards a flexible and systematic “catalogue” of engineered barrier components and associated repository infrastructure. To support this development, novel methodology for both developing and comparing repository design options for Japanese vitrified high-level radioactive waste (HLW) has been examined. This paper will outline the background of the project and, in particular, some novel approaches examined for facilitating optimisation of practical repository designs. It is complemented by a companion paper - Matsumoto et al: Application of Formal Knowledge Engineering Approaches to Develop A Design Catalogue for A Japanese HLW Repository -, which describes the repository design process in more detail and illustrates results of first dry runs of the methodology.
Reduction in the Thermal Conductivity of Thermoelectric Titanium Oxide by Introduction of Planar Defects
Authors: Harada Shunta , Tanaka Katsushi , Inui Haruyuki 
Published: April 2011

AbstractThermoelectric properties of a homologous series of Magnéli phase titanium oxides TinO2n-1 (n = 2, 3..) have been investigated. Dense polycrystalline specimens with nominal composition of TiO2-x (x = 0.10, 0.20) have been prepared by conventional hot-pressing. X-ray diffraction analysis has revealed that prepared specimens are slightly reduced during hot-pressing. Electrical conduction is of n-type for all prepared titanium oxides and electrical resistivity and absolute values of Seebeck coefficient decrease with increasing oxygen deficiency. The carrier concentration of Magnéli phase titanium oxide increases with increasing oxygen deficiency. Lattice thermal conductivity decreases with increasing oxygen deficiency by more than 60% at room temperature and 40% at 773K compared to TiO2, which can be due to the presence of dense planar defects. The largest thermoelectric figure of merit Z, 1.6×10-4 K-1 at 773K, was obtained in TiO1.90 hot pressed specimen.
Transient Thermal Imaging of Si/SiGe superlattice and bulk Si microrefrigerators
Authors: Michel Hélène , Coppard Rémi , Kendig Dustin , Christofferson James , Maize Kerry , Shakouri Ali 
Published: April 2011

AbstractIn this paper, we present a systematic study of the transient cooling in different Si/SiGe superlattices as well as bulk silicon microrefrigerators. Transient thermoreflectance imaging is used to obtain the temperature map of the device with sub micrometer spatial, 100ns temporal and 0.1C temperature resolution. It is shown that Peltier cooling dominates in the first 10-30 microseconds before Joule heating in the active and buffer layers reach the top surface. The transient characterization shows that at the optimum current for maximum steady-state cooling, the response of bulk silicon cooler is 25% faster than the 3 microns thick superlattice device and that of the 6 microns thick superlattice is 25% slower. However, it is possible to increase the cooling speed by a factor of two or three, down to 3.6 microseconds, by overdriving the current at the expense of the reduced steady-state cooling.
Thermo-Magnetic, Piezo-Electric and Electroactive Energy Harvesting Devices
Authors: Jean-Mistral Claire , Carlioz Louis , Defosseux Maxime , Marzencki Marcin , Cugat Orphèe , Delamare Jèrôme , Basrour Skandar 
Published: April 2011

AbstractWe present three approaches to harvesting ambient energy, based on complementary physical effects in order to exploit three kinds of energy available for harvesting:Mechanical vibrationsMechanical vibration energy can be harvested with resonant mechanical structures excited by the vibrations; this scavenged energy is then transformed into electricity by piezoelectric materials. We propose to use thin piezoelectric layers deposited on the resonant structure.An on-chip integrated prototype, using a seismic mass at the end of a Si cantilever beam coated with a piezoelectric AlN film (overall volume 5 mm3), produces 30 nW of rectified power at 3 V under 0.4 g acceleration, which is enough to power a wireless sensor. Power conditioning electronics adapted to ultra-low voltage input is also proposed, which can efficiently charge a storage capacitor under very low accelerations. The fully micro-fabricated System on a Package combines a MEMS generator and ASIC power management circuit.Evolutions of ambient temperatureA permanent magnet is attached to a PZT/brass bimorph, and placed near a "thermo-magnetic" material (FeNi) which Curie temperature can be tuned around the ambient. During slow cooling or heating by the ambient air, the FeNi magnetic properties vary slowly and thus the attraction force between the FeNi and the NdFeB magnet varies slowly. Despite the slow global evolutions, the opposition between the linearity of the bimorph bending and the strong non-linearity of the magnetic attraction over distance leads to brutal clamping or release of the magnet around Tc: the piezo can then efficiently convert these fast deformations into electricity. Operational temperature range can be set by tuning the FeNi composition to obtain a predefined Curie point; hysteresis between the cooling/heating thresholds can be tuned by modifying the gap between the magnet and the FeNi.The cm-scale prototype generates a peak voltage of 35 V on release (T > Tc). For a discharge time of 0.1 s through a 1 MΩ load, the total energy harvested is 13.5 μJ per stroke, i.e. 1.35 mW of average power (respectively -14 V, 2.2 μJ and 0.22 mW on clamping when T < Tc). Output power is surprisingly constant for various load values tested. Scaling effects must now be addressed to assess the feasibility of an integrated MEMS generator and its potential efficiency.Low-frequency, large amplitude bending from human motion:A very light, flexible electro-active polymer membrane (50 x 30 mm, 31 μm thick) operates in a large frequency spectrum from quasi-static to dynamic range. It scavenges 0.1 mJ per cycle at 1 Hz, under 170 V and constant charge Q: 100 μW is enough to supply a low-power system.Improvements under investigation include achieving poling voltage with piezoelectric polymer or electrets polymer, using multi-stack scavengers to miniaturize the structure and to decrease the poling voltage V, and integration into textile.
A thermophotonic heat pump/heat engine
Authors: Oksanen Jani , Tulkki Jukka 
Published: April 2011

AbstractWe propose a solid state heat pump based on photon assisted heat transfer between two large-area light emitting diodes coupled by the electromagnetic field and enclosed in a semiconductor structure with a nearly homogeneous refractive index. Ideally the thermophotonic heat pump (THP) allows heat transfer and electricity generation at the Carnot efficiency, but in reality there are several factors that limit the efficiency. We present a numerical model that accounts for the most important losses of the thermophotonic heat pump to study the operating regimes and the fundamental limitations of the THP structure. The results show that the thermophotonic heat pump has potential to outperform heat pumps based on the thermoelectric effect especially for heat transfer across large temperature differences. In energy harvesting applications the performance of the THP is good for small power densities, but drops at high power densities unless the losses in the structure can be efficiently minimized.
Constrained Deformation of TiAl PST Crystals
Authors: Goto Kengo , Kishida Kyosuke , Inui Haruyuki 
Published: April 2011

AbstractTiAl polysynthetically twinned (PST) crystals were deformed under plane strain condition, in which the anisotropic macroscopic deformation of PST crystals is restricted with a channel die, in order to clarify the deformation behavior of TiAl/Ti3Al lamellar structure under constraint conditions. TEM analysis of deformation modes together with the Taylor analysis reveals that all TiAl orientation variants deform to yield the relaxed-constraint-type plastic strain, where three shear strain components are not zero for each TiAl variant but are macroscopically compensated to zero by the existence of twin-related TiAl lamellae at the early stage of deformation. The Taylor analysis assuming the relaxed constraint conditions is found to be adaptable for predicting the operative deformation modes in TiAl at the early stage of deformation and also for correlating quantitatively the stress-strain behavior of PST crystals under external constraint with those under the unconstraint condition.
Laser-Assisted Atom Probe Analysis of Bulk Insulating Ceramics
Authors: Ohkubo Tadakatsu , Chen Yimeng M. , Kodzuka Masaya , Li Fang , Oh-ishi Keiichiro , Hono Kazuhiro 
Published: April 2011

AbstractA Yb:KGW femtosecond laser (400 fs) with 3rd and 4th harmonic generators (wavelength = 343 and 258 nm) was adopted to a locally built 3DAP instrument to assist field evaporation from ceramics tips that were bonded on tungsten wire. Using this setting, we have demonstrated that quantitative atom probe tomography is possible from Y2O3-ZrO2-MgAl2O4, (Ce,Y)O2, Li(Co,Ni,Mg,Al)O2 sintered bulk ceramics, which are all insulators.
Characterization and Evaluation of the Integrity of the Onshore Pipelines
Authors: Hernández S. L. , Adame M. , Gonzalez J. , Padilla D. , Contreras A. 
Published: April 2011

ABSTRACTThe pipelines are the main transport and distribution system of production in the oil industry, which are subject to environmental and operational conditions which are not favorable for the operation of the pipelines and sometimes represent the risk of accidents and high economic losses. The evolution of risk begins with a systematic search of possible threats to the integrity of the pipeline. The identification of potential threats should not be limited to known risk categories reviewed, but must complete the steps to find new and unique expressions of risk and the study of particular cases. Thus, the importance of a comprehensive risk assessment of the transmission pipeline is crucial. In this paper an integrity assessment for corrosion damages in pipelines was developed through a methodology based on risk analysis to estimate the propagation rate on the time, the size, location and number of damages. To perform this study a data obtained from smart pig runs and an artificial neural network (ANN) model with retro propagation was used. From the data obtained from launching smart pigs on the pipeline it was carried out the training of the neural network, later on it was applied the network previously trained to get the predictions of damages on the pipeline, considering that pipeline did not have any maintenance.
A Study of the Kinetics of Polylactic Acid Crystallization by Image Processing
Authors: Hernández-Sánchez F. , Carrillo-Escalante H. 
Published: April 2011

ABSTRACTThe polylactic acid (PLLA) is commonly used in the biomedical application. The physical and mechanical properties of PLLA depend on the molecular weight, crystallinity, and synthesis. In this work, we study the PLLA crystallization kinetics. One of the main attractive of these polymers is that its degree of crystallinity can easily be modified, from amorphous state to a high crystallinity degree. In this study a new technique is applied to follow the crystallization kinetic. An optical microscope with cross polarizers, warming plates and video camera were used. A series of images were obtained under isothermal conditions to observe the growth spherulite. Since an image is composed by pixels and each pixel has a value from 0 to 255, which represents gray intensity, being zero for black and 255 are white. Then, the pixels average versus time was plotting and from the plots crystallization kinetic and secondary crystallization are easily obtained.
Phase Stability of the Al-Cu-Co Decagonal Phase Under Conventional Solidification
Authors: Téllez-Vázquez J.O. , Patiño-Carachure C. , Bedolla-Jacuinde A. , García-De León E. , Pérez R. , Rosas G. 
Published: April 2011

ABSTRACTAl65Cu15Co20and Al67Cu13Co20(% at.) alloys with composition near to the quasicrystalline decagonal phase was produced by melting in an induction furnace and solidified at room temperature. The structural characterization was carried out by X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM) and scanning electron microscopy (SEM). For the structural model of decagonal quasicrsytals, it is important to know which crystalline phases have a structural relationship on the formation and decomposition of this type of phases. In the present investigation, the decagonal phase usually coexist with small amounts of the Al(Cu,Co) cubic phase of B2 type. Then, the quasicrystalline (QC) phase is outside of a single-phase region under equilibrium conditions at room temperature. DSC and TGA techniques showed the thermal stability of the alloy system up to 1000 °C.
Structural Characterization of Aluminum Foams Obtained by Powder Metallurgy
Authors: León-Patiño C. A. , Monje-García M. A. , Aguilar-Reyes E. A. , Bedolla-Becerril E. 
Published: April 2011

ABSTRACTThe porous structure of aluminum foams was quantitatively monitored in terms of pore density, pore area, and shape and size distribution using image analysis; then, related to density and expansion profiles by interrupted experiments. This practice offers important information in the control and reproducibility of foams. The aluminum foams were produced by the powder compact melting method at 800°C. The foamable precursors consisted in uniaxial cold pressed Al-TiH2 mixtures compacted at 387 MPa; the pressure applied and particle size distribution of the mixture originated preforms with 95.9% densification. This procedure eliminated the traditional hot-compaction step; besides, the amount of foaming agent was kept to a minimum of 0.5 wt.% TiH2. A volume expansion of 215 to 236% and densities from 0.7730 to 0.8206 g/cm3were obtained in a time window of 420 to 570 s. The calculated shape factors and Feret diameters defined how the roundness of pores varies with size all along the foaming process.
Biocompatibility and Anti-microbial Properties of Silver Modified Amorphous Carbon Films
Authors: Almaguer-Flores Argelia , Olivares-Navarrete René , Ximénez-Fyvie Laurie A. , García-Zarco Oscar , Rodil Sandra E. 
Published: April 2011

ABSTRACTInfection due microbes on implant surfaces has a strong influence on healing and long term viability of dental implants. The prevention and control of biofilms can be achieved by reducing the bacterial adhesion on the surface. The coating of medical devices with silver, or the addition of silver nanoparticles, are two possible ways to prevent device-associated infections. On the other hand, amorphous carbon films, in its different forms and compositions, have been studied as beneficial surface modification for implant materials. However, the bacterial adhesion on these films by oral bacteria in comparison to standard surfaces (Ti and SS) has been seen to be relatively high. In the oral cavity, the microbial ecology is complex and consists of hundreds of bacterial species, and therefore it is recommendable to study bacteria adhesion using various strains. In this work, we tested the biocompatibility and the anti-microbial properties of amorphous carbon films with the addition of silver nanoparticles. The a-C:Ag films were deposited by co-sputtering in an Argon plasma using a target made of graphite with a small piece of pure silver. Biocompatibility tests were performed using osteoblast-like cells (MG63) and included: cell proliferation, alkaline phosphatase specific activity and OPG. The bacterial adhesion test was evaluated after 1, 3 and 7 days of incubation. We used nine oral bacteria strains: Aggregatibacter actinomycetemcomitans serotype b, Actinomyces israelii, Campylobacter rectus, Eikenella corrodens, Fusobacterium nucleatum ss nucleatum, Parvimonas micra, Porphyromonas gingivalis, Prevotella intermedia and Streptococcus sanguinis. The effect of including silver in the a-C films was studied by X-ray Diffraction, Energy Dispersive spectroscopy, Scanning Electron Microscopy. The results showed that the films had silver nanoparticles (40-60 nm) uniformly distributed in the carbon matrix. The silver was crystalline with a maximum content of around 6 at%. The biological tests showed that a-C:Ag films had good biocompatibility properties, allowing the osteoblast to proliferate and produced osteogenic local factors. Concerning the antimicrobial properties of the a-C:Ag films, we did not observe an effect of the silver particles on bacterial adherence after 1 and 3 days of incubation; however, a significant reduction was observed after 7 days, compared to the a-C, Ti films or the bare SS substrate, suggesting that silver nanoparticles have a time-dependent antimicrobial effect.
Graphene Devices Processing Using Direct Writing Laser Lithography and Electrical Properties Characteristics
Authors: Leon Jorge Augusto , Alves Elmo Salomão , Elias Daniel Cunha , Moreira Leandro Malard , Barbosa Tiago Campolina , Pimenta Marcos Asunção , Plentz Flavio Orlando 
Published: April 2011

AbstractIn this work, we establish the use of lithography technique by laser direct writing for fabricating bilayer graphene devices. This technique, which is based on direct laser writing on graphene coated with a photoresist is simple to implement, versatile, and capable of achieving good throughput. Double-layer graphene flakes were obtained by micromechanical cleavage of graphite producing large graphene samples up to 40μm in size. The presence of a bilayer of graphene on SiO2/Si substrate was verified by optical microscopy and resonant Raman spectroscopy. We have measured the four-terminal resistance as a function on the back-gate voltage and found initially p-type doping in graphene, but annealing inside cryostat at 127C° in He atmosphere, the samples become n-type. Our measurements show electron mobility reached values around ˜1,900 cm2/V.s at high electron concentration.