bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thermal Diffusivity Measurement in Solids by means of the Photoacoustic Technique
Authors: Rojas-Trigos José B. , Calderón A. , Marín E. 
Published: April 2011

ABSTRACTWe report thermal diffusivity measurements for samples of silicon, gallium arsenide and cupper by means of the photoacoustic technique in a heat transmission configuration in order to obtain a comparison between the results obtained with the use of the conventional RG-model and our SP-model (based in a square periodical heat source) in the fitting process to the experimental data. Our results show that our SP-model is accurate to obtain a good fitting with the experimental data and it improves notably the results obtained with the RG-model.
Characterization of Zinalco Alloy Superplastically Deformed Using Orientation Imaging Microscopy
Authors: Mitsuo Ramos A. , Elizabeth Martínez F. , Jesús Negrete S. , G. Torres-Villaseñor 
Published: April 2011

ABSTRACTZinalco alloy (Zn-21mass%Al-2mass%Cu) specimens were deformed superplastically with a strain rate (ε) of 1×10-3 s-1 at homologous temperature (TH) of 0.68 (5 ). It was observed neck formation that indicate nonhomegeneus deformation. Grain size and grain boundaries misorientation changes, due superplastic deformation, were characterized by Orientation Imagining Microscopy (OIM) technique. It was studied three regions in deformed specimens and the results were compared with the results for a specimen without deformation. Average grain size of 1 mm was observed in non-deformed specimen and a fraction of 82% for grain boundary misorientation angles with a grain boundaries angles between 15° and 55° was found. For deformed specimen, the fraction of angles between 15° and 55° was decreced to average value of 75% and fractions of low angle (<5°) and high angle (>55°) misorientations were 10% and 15% respectively. The grain size and high fraction of grain boundary misorientation angles between 15° and 55° observed in the alloy without deformation, are favorable for grain rotation and grain boundary sliding (GBS) procces. The changes observed in the fraction of favorable grain boundary angles during superplastic deformation, shown that the superplastic capacity of Zinalco was reduced with the deformation.
The Weight Change of SAPO-34 Catalyst During MTO Process in TGA Reactor
Authors: Hu Hao , Ying Weiyong , Cao Fahai , Fang Dingye 
Published: April 2011

ABSTRACTThe Thermax 700 thermo gravimetric analysis (TGA) instrument is introduced for the investigation of the weight change of SAPO-34 catalyst during methanol-to-olefin (MTO) process. By the use of a special sample basket with screen bottom, the TGA instrument can be viewed as fixed-bed reactor, while the weight change of SAPO-34 during MTO reaction can be recorded online. It is noticed that the SAPO-34 catalyst experiences a procedure of dehydration as furnace temperature rises; hence the weight increase of SAPO-34 during MTO reaction should be calculated based on the weight after dehydration. It is checked that the increase of weight is mainly coke ignore of adsorbates. In the range of 648∼773K temperature and 7.08∼35.9h-1 (WHSV) space velocity, the maximum coke deposition is roughly 25% independent of reaction condition. The coke formation experiences a stage of fast increase soon after reaction initiates, while slows down apparently after 18% coke is deposited on the catalyst. Higher temperature, space velocity and methanol partial pressure accelerate the coking rate. Temperature plays an important role in the type of coke formation, which can be distinguished directly by the colour of completely deactivated catalyst. The deactivated catalyst in lower temperature experiences a weight loss with partly recovery of catalyst activity as temperature rises in the hydrothermal atmosphere. The phenomenon of weight loss with catalyst regeneration will not occur as reaction temperature decreases for deactivated catalyst, as well as the different DTA curves for coke burning, are also evidences for the different type of coke formation on SAPO-34 catalyst in different reaction temperature.
Stress Corrosion Cracking Behavior of X60 Pipe Steel in Soil Environment
Authors: Velazquez Z. , Guzman E. , Espinosa-Medina M‥A. , Contreras A. 
Published: April 2011

ABSTRACTStress corrosion cracking (SCC) susceptibility of API X60 pipeline steel in a soil solution by slow strain rate tests (SSRT), and surface fracture analysis was investigated. The SSRT were performed at strain rate of 25.4 × 10-6 mm/sec in a glass autoclave containing the soil solution called NS4 with pH of 3 and 10 at room temperature and 50°C. Both anodic and cathodic polarization potentials of 200 mV referred to Ecorr was applied. The results of ratio reduction area (RRA), time to failure ratio (TFR) and elongation plastic ratio (EPR) indicate that X60 pipeline steel was susceptible to SCC at pH 3 and cathodic polarization of -200 mV at room temperature and 50°C. Scanning electron microscopy (SEM) observations of these specimens showed a brittle type of fracture with transgranular appearance. The SCC process and mechanism of X60 steel into NS4 solution was hydrogen based mechanism. With the different applied potentials the dominance of SCC process changes. At low pH the temperature effect on SCC susceptibility is more noticeable at 20°C. However at high pH this effects changes, being the steel more susceptible to SCC at 50°C.
Synthesis of ZnO2 Nanocrystals Produced by Hydrothermal Process
Authors: Esparza R. , Aguilar A. , Escobedo-Morales A. , Patiño-Carachure C. , Pal U. , Rosas G. , Pérez R. 
Published: April 2011

ABSTRACTZinc peroxide (ZnO2) nanocrystals were directly produced by hydrothermal process. The nanocrystals were synthesized using zinc acetate as precursor and hydrogen peroxide as oxidant agent. The ZnO2 powders were characterized by X-ray powder diffraction and transmission electron microscopy. The results of transmission electron microscopy indicated that the ZnO2powders consisted of nanocrystals with diameters below to 20 nm and a faceted morphology. High resolution electron microscopy observations have been used in order to the structural characterization. ZnO2 nanocrystals exhibit a well-crystallized structure.
Probing Luminescence from Conical Bubble Collapse
Authors: Navarrete M. , Sánchez C. , Godínez F. A. , Valdés R. , Mejía E. , Villagrán M. 
Published: April 2011

ABSTRACTA summary of experimental findings on the luminescence from conical bubble collapse, CBL is presented. Spatial, temporal, and spectral features of luminescence were investigated. In the experimental runs, two inert gases (Ar, Xe) and 1,2-Propanediol, PD, as work liquid were used. Single and multiple light emission events were recorded. Results show that there is a spectral evolution inside each pulse and through the whole experimental sequence. The average spectra consist of a broad continuum background, on which line emissions of OH°, CN, Na+, K+, and Swan lines are superimposed. An increase in continuum intensity from 300 to 860 nm was observed. The molecular and atomic lines as well as the continuum emission arise from different chemical pathways that take place during the bubble compression. Pathways come from the degradation of the liquid due to the repetition of the compression process, resulting in changes of the thermo-chemical conditions inside the cavity, such that each collapse was different. This becomes evident, by using low gas pressures, in which the luminescence was spatially and temporally non uniform. On the other hand if Xe instead of Ar is used the intensity of the luminescence increased one order of magnitude. These findings indicate that several components are presents in the bubble, besides the residual air and inert gas, vapor and liquid droplets, and within the latest water vapor, inert gas and alkali solutions are dissolved.
Development of Biomaterials With Therapeutically Medicinal Application
Authors: Domínguez Patiño M.L. , Chávez M. , Rojas Bribiesca M.G. , Rodríguez-Martínez  , Valladares Cisneros G. 
Published: April 2011

ABSTRACTA biomaterial is a non-biological material used in a medical device in order to interact with biological systems. Many different types of materials such as metals, ceramic or natural and synthetic polymers can be included in this definition. Most of the time they are used as mixed materials where the combination of two or more substances with their own characteristics results in a new material whose features will be superior to the ones of its components for the achievement of the objectives preset [1]. According to the length and characteristics of the contact with an organism, biomaterials can be classified as temporal and permanent and of intra or extra corporal location. According to their functions they can be used as support, diagnostic or treatment [2]. Some biomaterials contain drugs and they are considered as medicines, others may include living cells and become the so called “hybrid biomaterials”.Elaboration of a biomaterial from a medicinal plant called Tonacaxochitl (Distictis buccinatoria (D.C.)) is presented in this work. The Tonacaxochitl is an endemic plant from Morelos state in Mexico. By means of solvents, active principles were extracted from the plant in an integral way. Obtained product (plant extract) was mixed with materials like clay and toncil. The biomaterial obtained from clay and toncil has shown anti-inflammatory activity, what makes it a useful tool for topic treatment of inflammation. Tests are being carried out with different extract concentrations to specify suitable concentrations to get effects on specific parts of the human body.
Microfluidic Synthesis and Functional Patterning for Advanced Nanotechnology
Authors: Choi Kyung 
Published: April 2011

AbstractIn this study, we introduce ‘molecularly imprinted polymer' (MIP) system, which has receptor or binding sites with specific molecular recognitions.Due to the receptor or binding sites in MIP's systems, it can be used for developing bio- or chemical sensors.To fabricate bio-sensors, bio-molecules have been incorporated into MIP's systems as template molecules, but some bio-molecules are sensitive thus denatured during engineering processes.For this reason, bio-sensor fabrications by conventional UV photolithography have shown some limitations.We demonstrate here a photopatterning process, a micromolding in capillary technique (MIMIC) technique, to photopatterning a MIP's system containing a bio-molecule template.The MIMIC technique uses the photo-masks for photopolymerizing MIP's monomer solutions.The photomask is based on silicon rubbers, which are optically transparent and also minimize any damages of sensitive bio-molecules during photo-polymerizations. For visualizing lithographic performances of MIP's systems, we used a fluorescent template molecule to present a comparative result of MIP's photo-cured patterns.It shows a clear different in MIP's patterns with and without the template.We also employed a microfluidic approach to produce micro-sized MIP's particles, which contribute to increase the sensitivity of bio-molecule sensors/devices.
Fourier Thermal Analysis of Eutectic Al-Si Alloy with Different Sr Content
Authors: Aparicio R. , Barrera G. , Trapaga G. , Gonzalez C. 
Published: April 2011

AbstractThe purpose of this work is to explore the capability of Fourier Thermal Analysis (FTA) to detect differences in solidification kinetics between unmodified and Sr modified eutectic Al-Si alloy obtained from the same base alloy. Experimental melts are produced in silicon carbide crucibles using an electrical resistance furnace and burdens of A356 alloy and commercial purity Si. The addition of strontium to the melts is accomplished using Al-10 pct Sr master alloy rod. Chemical composition is controlled using spark emission spectrometry. The changes in microstructure are characterized using optical microscopy. Thermal analysis are performed in cylindrical stainless steel cups coated with a thin layer of boron nitride, using two type-K thermocouples connected to a data acquisition system. Experimental cooling curves are numerically processed using FTA. Results show changes in solidification kinetics of eutectic Al-Si alloy with different Sr content. These changes, measured at the beginning and during solidification of the probes, can be related to the changes in nucleation and growth causing the differences detected during microstructural characterization of the probes.
Mechanofusion Processing of Metal-Oxide Composite Powders for Plasma Spraying
Authors: Cuenca-Alvarez Ricardo , Monterrubio-Badillo Carmen , Ageorges Hélêne , Fauchais Pierre 
Published: April 2011

AbstractComposite particles destined to build plasma sprayed coatings, are prepared by the mechanofusion process (MF). These particles consist of a stainless steel core particle coated by finer particles of alumina. Changes induced by the MF process are monitored by SEM, DRX, and laser granulometry, revealing that the dry particle coating process is governed by agglomeration and rolling phenomena. Simultaneously, the MF performance is controlled by the operating parameters such as the compression gap, the mass ratio of host to guest particle, and the powder input rate. The mechanical energy input leads to a nearly rounded shape of the final composite particles; however, no formation of new phases or components decomposition is detected by XRD analysis. The resulting composite powder features optimal characteristics, concerning particle shape and phases distribution, to be plasma sprayed in air.
Influence of Tempering Temperature in Wear of AISI T15 HSS Tools Produced by HIP and Liquid Phase Vacuum Sintering
Authors: Lima Emmanuel P. R. , das Neves Maurício D. M. , Delijaicov Sérgio , Filho Francisco A. 
Published: April 2011

AbstractThis work aims to investigate the influence of tempering temperature in the wear resistance of AISI T15 HSS tools produced by two different sintering processes – hot isostatic pressing (HIP) and liquid phase vacuum sintering. All materials are submitted to annealing at 870°C, quenching at 1210°C and triple tempering at 540, 550 and 560 °C. Density measurements, hardness and bend strength (transversal rupture strength – TRS) tests are accomplished. To identify the present phases and to evaluate the obtained microstructures, analysis in optical microscopy, SEM and EDX are done. Interchangeable inserts are manufactured by electrical discharge machining process. Frontal machining without coolant of normalized AISI 1045 steel plates is employed. The cutting forces are monitored via a transducer basically constituted of an instrumented table with four load cells mounted with “Strain Gages” sensors capable to measure the cutting efforts. The tools wear is analyzed and used to estimate the performance of two different HSS tools. For both investigated materials, the tools tempered at 540 °C show the lowest wearing.
Thermoluminescence of Vanadium–Doped SiO2 Synthesized by a Sol-Gel Method
Authors: Burruel-Ibarra S. E. , Bernal R. , Díaz-Flores L. L. , Cruz-Vázquez C. , Orante-Barrón V. R. , Castaño V. M. 
Published: April 2011

AbstractThermoluminescence (TL) properties of pulverized SiO2:V monoliths synthesized by a solgel method, and annealed at 1273 K during 12 h under air, are presented in this work. Characteristics TL glow curves display a complex shape with at least three maxima located at ˜379, ˜543 and ˜591K. The TL total signal exhibited a linear behavior for doses below 400 Gy. The integrated TL fades down 26 % after 3 h elapsed between irradiation and the corresponding TL readout. These results lead to conclude that annealed SiO2:V is a promising material for ionizing radiation detection and dosimetry.
Nucleation and Growth of Diamond Thin Films: The Role of Temperature and Pressure
Authors: Morales J. , Bernal R. , Cruz-Vazquez C. , Salcido-Romero E.G. , Castaño V.M. 
Published: April 2011

AbstractDiamond thin films were deposited onto Si (100) substrates using liquid a solution of water and acetone, ethanol, methanol and commercial Tequila as precursors by the Pulsed Liquid Injection Chemical Vapor Deposition (PLICVD) technique. Temperature was varied from 550 °C to 850 °C. In this work we attempted to find a crystal diameter dependence on temperature and pressure from the experimental data. The goal in this work is to found a function that can be adjusted to the experimental data.
Synthesis of Single-Crystalline Silicon Nitride (α-Si3N4) Nanowires with Controlled Diameters by Nitriding Cryomilled Nanocrystalline Silicon Powder
Authors: Chen Fei , Wang Zhihao , Shen Qiang , Huang Zhixiong , Zhang Lianmeng 
Published: April 2011

AbstractIn the present work, silicon nitride nanowires (SNNWs) have been synthesized via nitriding cryomilled nanocrystalline silicon powder. The silicon powder exhibits a fine polycrystalline structure after the cryomilling process, with an average grain size of 25 to 125 nm at various cryomilling times. The SNNWs that form after the nitridation of the cryomilled silicon powder exhibit single crystal structure and are 20 to 100 nm in diameter and ∼10 µm in length. The diameter of the nanowires is in agreement with the grain size of the cryomilled Si powder. Microstructural characterization reveals that the as-synthesized nanowires have a hexagonal structure and their primary growth direction is along the [0001] direction. The formation of the Si–N–Si bond during the cryomilling process, as investigated theoretically with density functional theory, promotes the subsequent synthesis of the α-Si3N4 nanowires. The mechanism for nanowire formation appears to be a vapor-solid (VS) reaction.
Methanol Conversion on SAPO-34 Catalysts Synthesized by Tri-templates
Authors: Ye Liping , Cao Fahai , Ying Weiyong , Fang Dingye , Sun Qiwen 
Published: April 2011

AbstractThe effect of different combinations of a new tri-templating agent TEAOH/DEA/TEA, namely tetraethyl ammonium hydroxide (TEAOH)/diethylamine (DEA)/triethylamine (TEA), on the catalytic performance of SAPO-34 was investigated in MTO conversion. It was found that SAPO-34 and SAPO-5 are competing phases at TEA concentrations higher than 40 %. Pure SAPO-34 with high crystallinity, large BET surface area and small crystal size (0.8~1.4μm) was obtained at a low TEA concentrations. The combination of TEAOH/DEA/TEA strongly governed the acidity of crystals. TEAOH:DEA:TEA=0.67:0.67:0.67 gave an economical catalyst active in MTO reaction with 100 % methanol conversion, 89.39 % ethylene and propylene selectivity, a longest lifetime and a high coke capability of 24.2 wt %.
Synthesis of Propylene Carbonate Catalyzed by Copper-containing Hydrotalcite-like Compounds
Authors: Xie Xianmei , Duan Lian , Wu Zhenghuang , Wang Lina , Yan Kai , Du Lei 
Published: April 2011

AbstractCuFe-Hydrotalcite-Like Compounds (CuFe-HTLcs) were synthesized by coprecipitation with Cu(NO3)2·6H2O, Fe(NO3)3·9H2O, NaOH and Na2CO3 solution. The sample with Cu2+ / Fe3+ = 2 was of the highest crystalline characterized by XRD and particle size distribution. The synthesis of propylene carbonate from 1,2-propanediol (PG) and urea was performed to evaluate the catalytic activities of the CuFe-HTLcs. The effects of reaction time, temperature, dosage of catalyst on the synthesis of propylene carbonate were fully discussed. The optimal reaction conditions were determined by using orthogonal test design: reaction temperature 170 °C, dosage of catalyst 0.2 g, and molar ratio of PG to urea 2:1, reaction time 3 h. Under the optimal conditions, the conversion of urea nearly reached 100 %, and the selectivity of propylene carbonate was up to 90.4%.
Microwave Hydrothermal Synthesis of Bimetallic (Ti-V) Ions Modified MCM-41 for Epoxidation of Styrene
Authors: Guo Yajie , Wang Guangjian , Wang Yuran , Li Zhengwang , Liu Guangqing , Liu Yiwu 
Published: April 2011

AbstractMesoporous molecular sieves MCM-41 modified by single (Ti) and bimetal (Ti-V) ions with highly ordered hexagonal arrangement of their cylindrical channels were prepared by direct synthesis under microwave–hydrothermal (M–H) conditions at 403K. Characterizations with powder X-ray diffraction (XRD), 29Si magic-angle spinning (MAS) NMR, N2 adsorption–desorption, Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray photoelcctron spectra(XPS) and transmission electron microscopy (TEM) showed that Ti and V ions were introduced into MCM-41 under M-H conditions and Ti/V-Si bond was formed. Results revealed that all the samples were of a typical hexagonal arrangement of mesoporous structure. The modified materials were high active and selective in the epoxidation of styrene at 343 K in comparison with single-functional MCM-41. Moreover, compared to conventional method, the presented microwave hydrothermal synthesis of molecular sieves greatly improved the selectivity to styrene oxide, e.g., it reached 58.6% at styrene conversion of 18.7% over Ti-V-MCM-41 (50).
Hydrogen Storage in Ti-Zr Based Systems
Authors: Salmones J. , Zeifert B. , Ortega-Avilés M. , Contreras-Larios J. L. , Garibay-Febles V. 
Published: April 2011

AbstractThis research contributes to the study of hydrogen storage of two Ti-Zr based systems using (I) titanium dioxide (TiO2) + zirconium acetylacetonate (C20H28O8Zr) and (II) titanium dioxide (TiO2) + zirconium tetrachloride (ZrCl4) as starting materials. Both systems were prepared by mechanical grinding under the same conditions, with composition of 50 wt.% Ti and Zr and milling time of 2, 5, 7, 15, 30 and 70 hrs. The samples were evaluated by hydrogen absorption tests and characterized by BET, XRD and TEM. The results of hydrogen storage at different pressures but same temperature showed that samples of the system I absorbed the largest quantities of hydrogen but difficult to release them, while the system II absorbed less amount of hydrogen but completely desorbed the absorbed hydrogen. The increase of the mechanical grinding time is directly associated with changes in hydrogen absorption capacity and formation of new components. The formation of oxide nanoparticles of Ti and Zr on the surface of TiO2in samples from series II was associated with the hydrogen absorption capacity. Keywords: hydrogen storage, Ti-Zr, mechanical milling, sorption.
Wet Air Oxidation of Phenol over Ru Based Catalysts – Effects of Support
Authors: des Los Monteros A. E. Espinosa , Lafaye G. , Torres G. , Barbier J. 
Published: April 2011

AbstractCatalytic wet air oxidation (CWAO) of aqueous solutions of phenol was performed on ruthenium catalysts supported on different oxides: TiO2, ZrO2 and their doped ceria mixtures. Phenol was chosen as a model pollutant molecule because of its wide use in industrial processes. All the samples were found to be highly active for phenol oxidation and the various titania-ceria mixtures were the most efficient for total organic carbon (TOC) removal. ICP analysis of the remaining solution after reaction revealed that ruthenium has not leached. Moreover, elementary analysis of the used catalysts showed that the deposition of carbonaceous species on the surface of the catalysts was rather low and was dependent on the nature of the support.
Photodegradation of Reactive Black 5 by Titanium Oxide Film Obtained with Ultrasonic Pyrolysis Technique
Authors: L. R. T. Hernández , Hernández-Pérez I. , V. D. Y. Medina , Becerril N. , Soyuqui S. 
Published: April 2011

AbstractThe present work reports the photodegradation results of the Reactive Black 5 (RB5) izo dye by using titanium oxide films as photocatalysts. The films were obtained by ultrasonic spray pyrolysis deposit technique from a 0.0076 M of Ti(IV)-acetyl-acetonate and N, Ndimethylformamide solution over corning glasses as substrates. The film obtained by deposition at 450 °C for 6.0 min shows the best photocatalysis behavior, which may degrade 50% of 100 ppm RB5 in a period of 120 min, as monitored with a spectra-photometer UV-Vis between 190 to 900 nm. After 180 minutes of degradation, a 70% conversion could be obtained. These results are better than that obtained with TiO2 powders as photocatalyst.