bluuebunny/crossref_metadata_2025_split huggingface dataset:
Anionic and Cationic Effects on the Crevice Corrosion Susceptibility of Alloy 22
Authors: Carranza Ricardo M. , Rebak Raul B. 
Published: April 2011

AbstractAlloy 22 is highly resistant to all forms of corrosion; however, it may suffer crevice corrosion in presence of chloride ions especially at temperatures higher than ambient and at anodic potentials. The susceptibility of Alloy 22 to suffer crevice corrosion is highly dependent on the type of electrolyte solution that is in contact with the alloy including variety of species in solution and their relative concentration. Laboratory research has shown that at a constant chloride concentration, the susceptibility of Alloy 22 to crevice corrosion is not influenced by the nature of the cations present in solution. On the other hand, that nature of the anions is highly influential. Of the anions present in ground water, only chloride is detrimental and the others are inhibitors or innocuous for crevice corrosion susceptibility. That is, the presence of the other anions counter balances the negative effect of chloride. The inhibition effect is explained and the likelihood that Alloy 22 would suffer crevice corrosion in contact with ground water is discussed.
Basic Research Needs on Physical Chemistry of Radionuclides in the Nuclear Fuel Cycle
Authors: Advocat T. , Ferry C. , Goutelard F. , Lamouroux C. , Wagner J.F. , Vautrin-Ul S. , Chaussey A. 
Published: April 2011

AbstractFrom uranium-ore treatment to spent fuel recycling, waste treatment and conditioning and to final storage of waste packages, radionuclides are involved in numerous chemical and physical reactions. The understanding of their chemical forms (speciation) and behavior as well (retention, complexation,...), as a function of the environment conditions (T, P, solid/liquid/gas interfaces), are key issues for the development of the industrial nuclear activities. Dedicated analytical tools are needed to determine the radionuclide concentrations and speciation in the liquids, solids and gas, over a wide range of concentrations and matrixes. The obtained experimental data on radionuclide speciation are integrated in dedicated data bases, supporting various models used to simulate the system behavior (i.e. RN migration under geological disposal, RN contamination in the primary fluids of nuclear power plants, RN behavior in the PUREX process, etc.). There are several needs in the following domains of the fuel cycle :♦ The development of innovative methods to enhance analytical performances of isotopic composition of elements in irradiated fuels or waste streams arising from processed spent fuels. Isobaric interferences may be suppressed by specific ion-molecules reactions in collision/cell coupled with Mass Spectrometer, instead of preliminary chromatographic separations.♦ The thermo chemistry at high temperature and pressure of the coolant fluids of the nuclear power plants, to model the solid/liquids interactions controlling its contamination by the activated products and hideout processes.♦ The development of scientific and operational models of the radiolysis of organic molecules and materials, under extreme conditions (γ and α radiolysis), to understand the controlling long-term degradation phenomena ( i.e. H2 degassing in the waste packages).♦ The fundamental understanding of sorption processes of redox sensitive elements such as U on specific mineral surfaces, in the presence of organic molecules, to develop dedicated tools for radionuclide monitoring and measurement in the environment.
The role of uranium peroxide studtite on the retention of Cs, Sr and Se(VI)
Authors: Gimenez Javier , Sureda Rosa , Pablo Joan de , Casas Ignasi , Martinez-Llado Xavier , Rovira Miquel , Martinez-Esparza Aurora 
Published: April 2011

AbstractThe formation of uranyl secondary solid phases onto the spent nuclear fuel surface might influence the radionuclide concentration in solution via, among others, sorption processes. In this work, the incorporation of some radionuclides onto the uranium peroxide studtite, UO2O2·4H2O, has been tested.The study was carried out in batch experiments where a known amount of studtite (0.05 g) was put in contact with 20 cm3 of radionuclide solution. Once equilibrium was reached, radionuclide concentrations in solution were determined by ICP-MS. The radionuclide amount attached to the solid was calculated from the mass balance. The S/V values of the experiments were also determined from BET specific solid surface area measurements.In this work, data on sorption of caesium, strontium, and selenium as a function of pH are presented. The behaviour of caesium and strontium are similar: a relatively high amount of radionuclide is sorbed at neutral to alkaline pH while there is almost no sorption at acidic pH. On the other hand, in the case of selenium, the sorption maximum occurs at acidic pH and there is almost no sorption at alkaline pH. The different behavior of the radionuclides is related to the element speciation in solution and the surface charge of the solid. Strontium and caesium are sorbed at alkaline pH because they are positively charged in solution and the surface of the studtite is negatively charged (>O- groups) while selenium(VI) sorbs at acidic pH because the surface of the studtite is positively charged, and the predominant selenium(VI) species in solution is anionic.These preliminary data indicate that the sorption capacity of uranyl secondary solid phases such as studtite is an important process to be considered when establishing the migration of different radionuclides released from spent nuclear fuel.
Application of Formal Knowledge Engineering Approaches to Develop a Design Catalogue for a Japanese HLW Repository
Authors: Matsumoto Masaaki , Sato Osamu , Okubo Hiroo , Makino Hitoshi , Ochi Yasuhiro , Hioki Kazumasa , Umeki Hiroyuki , Masuda Sumio , McKinley Ian G. 
Published: April 2011

AbstractThe volunteer siting of disposal facilities for vitrified high-level radioactive waste (HLW) and TRU waste in Japan results in a particular need for flexibility to allow repositories to be tailored to specific sites. Instead of a single reference concept, a “catalogue” of designs for individual repository components is being developed, which can then be combined to form optimum solutions for particular site boundary conditions. As highlighted in a companion paper – Makino et al: Supporting Development of Practical Designs for a Japanese HLW Repository –, which puts the repository design process in the context of the Japanese HLW programme, the complexity of this work justifies use of advanced Knowledge Engineering approaches. In this paper three components are described – development of the knowledge base, assessing tacit system understanding and production of innovative solutions to resolve conflicts between requirements.
Maximum Energy that can be Harvested from a Dielectric Elastomer Generator
Authors: Koh Adrian 
Published: April 2011

AbstractMechanical energy can be converted to electrical energy using a dielectric elastomer generator (DEG). The maximum amount of energy that can be harvested from a DEG is constrained by various modes of failure and operational limits. Known limiting mechanisms include electrical breakdown, electromechanical instability, loss of tension and rupture by stretch. These limits define a cycle where maximum energy can be harvested. The cycle was represented on work-conjugate planes, which can be used as a guide for the design of practical cycles. The amount of energy harvested is larger when a DEG is subject to equal-biaxial stretching.
The Effects of Precipitates and Mn-bearing Particles on the High Strain-Rate Compression of High Strength Aluminum
Authors: Elkhodary Khalil Ibrahim , Lee William , Cheeseman Bryan , Sun Lipeng , Brenner Donald W , Zikry Mohammed 
Published: April 2011

AbstractTransmission electron microscopy (TEM) and specialized dislocation-density based crystal-plasticity formulations and finite-element schemes were used to investigate the effects of nano-sized precipitates and micro-sized Mn-bearing particles on the behavior of Al-Cu-Mg-Ag alloys. By accurately representing crystallography and the morphology of the different precipitates, accurate predictions can be obtained that indicate that the nano-sized Ω and θ’ precipitates promote ductility and toughness by inhibiting shear-strain localization; whereas the micro-sized dispersed particles intensify localization. Collectively, the precipitates and dispersed particles, however, promote the strengthening of the alloy.
Cathodic Protection Effect on the Assessment of SCC Susceptibility of X52 Pipeline Steel
Authors: Contreras A. , Sosa E. , Espinosa-Medina M. A. 
Published: April 2011

ABSTRACTAssessment of anodic and cathodic potentials on stress corrosion cracking (SCC) of API X52 pipeline steel through slow strain rate tests (SSRT) was studied. The SSRT were carried out in a NS4 solution to simulated dilute ground water that has been found to be associated with SCC of pipelines. SSRT were performed and evaluated in air and in the NS4 solution at room temperature at an extension rate of 1×10-6 in/sec. Tests were performed at controlled electrochemical polarization potentials, both anodic and cathodic (100, 200, 400 mV) versus the open circuit corrosion potential. The results of reduction in area ratio (RAR), time to failure ratio (TFR) and plastic elongation ratio (PER) of the specimens tested in the soil solution indicate that X52 pipeline steel was susceptible to SCC at cathodic potentials. These specimens showed a brittle type of fracture with transgranular appearance. The SCC proceess and mechanism of X52 steel in the NS4 solution is mixed-controlled by both anodic dissolution and the hydrogen involvement. At positive potentials the SCC is based mainly on the anodic dissolution mechanism. When the applied potentials shifted negatively, the SCC on the steel follows mainly hydrogen embrittlement mechanism. This mechanism was confirmed through the internal cracks observed in the specimens.
Brazing Process to Repair Wide Gap Cracks of Inconel 738 Superalloy Components
Authors: Guzmán Isidro , Garza Alejandro , García Felipe , Castillo Jesús 
Published: April 2011

ABSTRACTBrazing process is a cost effective technique to repair wide gap cracks in turbine components made from difficult to weld nickel base superalloys. In this process boron and silicon are used as melting point depressants, however, form hard and brittle intermetallic compounds with nickel (eutectic phases) which are detrimental to the mechanical properties of brazed joints. In this paper the effect of brazing parameters such as temperature and time on final microstructure of brazed joint of nickel base superalloy Inconel 738 using a commercial filler metal alloy (Ni-11Cr-3.5Si-2.25B-3.5Fe) was investigated. The microstructure of the joint layer was characterized by optical and scanning electron microscopy; chemical composition was carried out by energy dispersive X-ray spectrometry (EDS) microanalysis and microhardness testing. The results showed that the formation of eutectic microconstituents, within the joint regions, was significantly influenced by the brazing parameters and gap size, also that formation of eutectic constituents decreased by allowing a sufficient amount of time for a complete isothermal solidification to take place at the brazing temperature.
Optical Characterization of the Twisted Nematic Liquid Crystal Display
Authors: Rickenstorff Carolina , Ostrovsky A. S. 
Published: April 2011

ABSTRACTA simple optical characterization technique is developed for to find the amplitude and phase modulation modes for the twisted nematic liquid crystal display (TN-LCD). The developed technique is based on intensity and pixel shift measurements of the interference pattern obtained from the TN-LCD sandwiched between two polarizers in a modified Young's experiment. Particularly, specimen LC2002 Holoeye is characterized and its amplitude and phase modulation curves as a function of image's gray level, bright B and contrast C are presented.
Synthesis of Au/TiO2 Thin Films for Photocatalytic Degradation of Methylene Blue
Authors: Palomar F. , Gómez I. , Zambrano Patricia 
Published: April 2011

ABSTRACTAu/TiO2 thin films have been prepared from Titanium Tetrabuthoxide-acetylacetone solution and buthanol as solvent by sol-gel and dip-coating technique. Au nanoparticles were prepared from HAuCl4 solution. The deposition of Au nanoparticles was by spray pyrolysis method. The films from the sol gel solution were heat treated at 450°C for 1 hour. The surface structures, morphology, composition and optical properties on the films were investigated by atomic force microscopy (AFM), optical microscopy (OM), X-ray Diffraction (XRD) and UV-Vis spectrometer. It was found the film consisted of anatase phase (TiO2), Au nanoparticles in the range of 50 to 100 nm, and few cracks on the surface remaining attached to the glass substrate. In this study, we measured the photocatalytic degradation of a methylene blue (MB) aqueous solution by a film prepared by the sol-gel and dip-coating methods TiO2 and Au/TiO2films prepared by spray pyrolysis method. We found that Au nanoparticles deposited on the TiO2films improved the photocatalytic activity and minor degradation time that TiO2 films.
Photoluminescence and In/Ga Intermixture in InAs/InGaAs DWELL Structures
Authors: Vivas Hernandez A. , Guerrero Moreno I.J. , Velázquez Lozada E. 
Published: April 2011

ABSTRACTThe photoluminescence (PL) and photoluminescence temperature dependences have been studied in InAs quantum dots (QDs) embedded in the In0.15Ga1–0.15As/GaAs quantum wells (QWs) with QDs grown at different temperatures (470–535 °C). Ground state (GS) related QD PL peaks shift into the red side with increasing QD growth temperature to 510 °C and the blue shift is observed when the temperature increased to 535 °C. The temperature dependences of GS PL peak positions were fitted on the base of Varshni relation and the fitting parameters were compared with the bulk InAs and the In0.21Ga0.79As allow. This comparison has revealed that for QDs grown at 490–510 °C the PL fitting parameters are the same as for the bulk InAs crystal. The DWELL structures with QDs grown at other temperatures have fitting parameters different from the bulk InAs. Last fact testifies that in these structures the Ga/In inter-diffusion between QDs and a QW has been realized. This Ga/In intermixture can be stimulated not only by the high temperature (535 °C), but by the essential elastic stress as well in the DWELL structure with lower QD densities.
Surface Functionalization of Polylactic Film with N-vinylcaprolactam using Photoinduction Process
Authors: Gutiérrez-Villarreal Mario H. , Guzmán-Moreno J. Gustavo 
Published: April 2011

ABSTRACTA versatile and non destructive technique for a chemical modification by grafting N-vinylcaprolactam (VCL) monomer on the polylactic (PLA) film surface is described. The film substrate is treated with a VCL solution, hexane and benzophenone (BP), the latest promotes the photo initiation. Grafting percentage is derived by a gravimetric method and the success in grafting is evaluated by contact angle technique, UV and ATR-FTIR analysis. The influence of the photoinitiator concentration is evaluated by the polymerization rate (Cp), grafting percentage (Cg) and grafting efficiency (Eg). The modified surface shows higher level of humectation or hydrophilicity, confirming successful surface functionalization of the polylactic acid film.
Metal-Graphite Couples Synthesized by Means of Mechanical Milling
Authors: Estrada-Guel I. , Carreño-Gallardo C. , Pérez-Bustamante R. , Herrera-Ramírez J. M. , Martínez-Sánchez R. 
Published: April 2011

AbstractThe aim of this work is the characterization of some graphite-metal couples prepared by mechanical milling (MM). The morphological and microstructural changes during MM of graphite processed with metallic powders of Cu, Ni and Ag (10 and 15 at. %) are studied. Milling is performed in a high-energy ball mill under an inert atmosphere during 1, 4 and 8 hours. The process is also repeated with a pure graphite sample in order to compare the role of metal type and concentration on the morphological characteristics of milled samples. The results show that increasing the concentration of metal particles accelerates the milling process as a result of faster work hardening and particle fracture. The results of X-ray diffraction analysis show that some crystallographic characteristics of the milled couples change as a function of milling time and metal addition. Also, SEM-EDS studies show an important effect of milling time on metal particle distribution in the prepared graphite couples.
Wear Properties of an In-Situ Processed TiC-Reinforced Bronze
Authors: Sanchez R. , Lopez H. F 
Published: April 2011

AbstractIn this work, an Al-bronze alloy is reinforced with TiC through reaction of the alloy melt with methane gas. The resultant alloy is then centrifugally cast in cylindrical molds. It is found that the surface at the inner diameter of the cast contained in-situ produced TiC as well as Fe-rich inclusions. Metallographic observations using optical and scanning electron microscopy confirmed the presence of TiC particles (30 % volume), alpha and beta grains including iron precipitates. Cylindrical pins are machined from the inner surface and tested under various conditions in a three pin on disk Falex machine. Pins are tested under a constant load of 2.86 MPa and friction and wear rates are determined from measurements of weight losses versus wear lengths. It is found that under the applied load the reinforced material exhibits high friction and relatively low wear when compared with the unreinforced material. Apparently, under these conditions the TiC particles become abrasive particles thus contributing to wear of the steel counter-face through three body abrasive wear.
Nanoceria Coatings and Their Role on the High Temperature Stability of 316L Stainless Steels
Authors: Mendoza-Del-Angel H. , Lopez H. F 
Published: April 2011

AbstractIn this work, a method is considered to produce uniform nanoceria surface coatings on 316L stainless steel such as dipping. Coated steels using the aforementioned method are exposed to high temperature 800–1000°C and their oxidation behavior is investigated. It is found that the nanoceria particles in the implemented coatings exhibit some growth during high temperature exposure. In addition, thermogravimetric determinations of oxidation resistance in coated and bare samples at 900°C clearly indicates that the nanoceria coated stainless steels exhibits a two fold reduction in mass gain when compared with bare ones. Optical and scanning electron microscopy are employed to characterize the developed oxide scale morphologies. It is found that in areas are nanoceria is not uniformly coated, Fe-rich oxide islands develop, whereas in coated regions the scale is Cr and Ce rich indicating that the scale is probably a Ce doped Cr oxide.
Manufacturing of Hybrid Composites and Novel Methods to Synthesize Carbon Nanoparticles
Authors: Fals Andres E. , Quintero Julio , Hernández F. C. Robles 
Published: April 2011

AbstractIn following are presented the characterization results of nanostructured hybrid composites using alumina matrix reinforced with nanostructured particles of Ni, Ti and soot. The soot used in this work is the byproduct from the synthesis of Carbon Nanotubes (CNT) or fullerene and contains traces (>1wt%) of either CNT or fullerene. Ni and Ti are used in this work for their inherent catalytic ability for heterogeneous nucleation of carbon nanostructures (nanotubes, fullerenes). The hybrid composites are produced by a combination of methods including mechanical milling, sonication, and Spark Plasma Sintering (SPS). Mechanical milling is conducted in high energy mills, the milled and as manufactured powders are sonicated to assure their dispersion, homogeneity and promote percolation of the components during sintering. Mechanical milling and SPS have positive effects to promote the synthesis of different carbon nanoparticles. For instance, it is observed that mechanical milling of fullerene soot sponsors the synthesis of nanostructured diamond particles and using SPS can be synthesized diamond too and fullerene. Although, it is important to notice that SPS conditions are critical to the amount and type of synthesized particles. The use of CNT soot sponsors porosity, hence lower density resulting in an ideal material for membrane and porous media applications. The results of characterization (X-Ray diffraction, electron microscopy (scanning and transmission)) and the mechanical properties (Vickers microhardness) are discussed accordingly.
Surface Coating TiO2 on Sepiolite Fibers and Application in Paper-making Waste Water Treatment
Authors: Guo Yajie , Wang Yuran , Wang Guangjian , Liu Zhengwang , Yang Zhengxing , Wang Fei 
Published: April 2011

AbstractThe purpose of this paper was to describe a method of preparing Fe-TiO2 supported on sepiolite fibers with sol-gel method and to discuss the feasibility of photocatalytic degradation of paper-making waste water with chemical oxygen depletion (CODcr) (Potassium dichromate method) as evaluation criterion of catalytic activity. As-fabricated catalysts consisted of TiO2 particles impregnated with iron and dispersed on the sepiolite fibers (S.F.s). The novel Fe-TiO2-sepiolite was characterized by specific surface area and pore size distribution measurements, scanning electron microscope (SEM), high resolution transmission electron microscope (HRTEM), X-ray diffraction (XRD) and Fourier transform Infrared spectrometer (FT-IR) etc. The effects of parameters such as the amount of Ti/sepiolite fibers, initial pH, H2O2, Fe-doped, concentration of waste water, etc. were studied in detail. The results indicated that the presence of sepiolite in the support preparation and its role as a matrix over which TiO2 particles were dispersed seem to play an important effect in the migration process of oxygen species through the support vacancies. On the basis of these properties, the most promising carriers to be used in a waste water treatment process were selected.
Synthesis and Catalytic Activity of Ni/Ce-MCM-41 Mesoporous Catalysts for Hydrogen Production
Authors: Wang J. A. , Guevara J. C. , Chen L.F. , Salmones J. , Valenzuela M. A. , Salas P. , Cao F. H. , Yu G. X. 
Published: April 2011

AbstractCe-containing MCM-41 mesoporous materials with large surface area and ordered pore structure system have been possible to be synthesized through a surfactant-assisted approach. The textural properties and structural regularity of the materials varied with the Si/Ce molar ratio. It is found that the band at 970 cm-1 in the FTIR spectrum of the Ce-MCM-41 mesoporous materials might be used as an indicator of the formation of the Ce-O-Si bond and its intensity as a measure of a degree of cerium ion substitution in the framework of Si-MCM-41. When Ni was loaded on the Ce-MCM-41 support, the Ni/Ce-MCM-41 catalysts show high catalytic activity which has strong temperature dependence. The methane conversion over these catalysts reached 60-75 % with a 100 % selectivity towards hydrogen.
New Route for the Tetraphenylfuran Synthesis Using a Superacid Sulfonic Clay (SASC) as Catalyst
Authors: Cea Carlos Damián , Labastida Eloy Vázquez , S Manuel Salmon , Valle Sergio O. Flores 
Published: April 2011

AbstractThe transformation of benzoin to tetraphenylfuran catalyzed with a superacid sulfonic clay under different reaction conditions was investigated. Three products with different yields were produced under a nitrogen stream and four products were obtained under an air atmosphere.