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101.
Sergio Neves Monteiro Regina Coeli M. P. Aquino Felipe Perisse D. Lopes 《Journal of Materials Science》2008,43(2):489-493
Natural lignocellulosic fibers are successfully replacing synthetic fibers as the reinforcement phase of composite materials
in many engineering applications, including automobile parts. In addition to well-known conventional lignocellulosic fibers,
others with promising properties, like that obtained from the leaves of the curaua plant (Ananas erectifolius) found in the Amazon region of Brazil, are now being considered. The present work investigated microstructural aspects associated
with the performance of curaua fibers in pullout tests carried out to characterize the fibers interfacial strength with a
polyester matrix. The results have shown that the naturally bonded filaments that constitute a curaua fiber present interspatial
voids between them. These voids play an important role in providing adherence of the fiber surface to a polyester matrix,
resulting in an effective reinforcement for a curaua-strengthened composite. 相似文献
102.
The Project SupraMetall: Towards Commercial Fabrication of High‐Temperature Superconducting Tapes
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103.
Avalanche‐Discharge‐Induced Electrical Forming in Tantalum Oxide‐Based Metal–Insulator–Metal Structures
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Katharina Skaja Christoph Bäumer Oliver Peters Stephan Menzel Marco Moors Hongchu Du Manuel Bornhöfft Christoph Schmitz Vitaliy Feyer Chun‐Lin Jia Claus Michael Schneider Joachim Mayer Rainer Waser Regina Dittmann 《Advanced functional materials》2015,25(46):7154-7162
Oxide‐based metal–insulator–metal structures are of special interest for future resistive random‐access memories. In such cells, redox processes on the nanoscale occur during resistive switching, which are initiated by the reversible movement of native donors, such as oxygen vacancies. The formation of these filaments is mainly attributed to an enhanced oxygen diffusion due to Joule heating in an electric field or due to electrical breakdown. Here, the development of a dendrite‐like structure, which is induced by an avalanche discharge between the top electrode and the Ta2O5‐x layer, is presented, which occurs instead of a local breakdown between top and bottom electrode. The dendrite‐like structure evolves primarily at structures with a pronounced interface adsorbate layer. Furthermore, local conductive atomic force microscopy reveals that the entire dendrite region becomes conductive. Via spectromicroscopy it is demonstrated that the subsequent switching is caused by a valence change between Ta4+ and Ta5+, which takes place over the entire former Pt/Ta2O5‐x interface of the dendrite‐like structure. 相似文献
104.
Cristina Yoshie Garcia Takeuchi Alessandra Marques Corrêa‐Afonso Hamilton Pedrazzi Welingtom Dinelli Regina Guenka Palma‐Dibb 《Microscopy research and technique》2011,74(3):287-291
Cigarette smoke is a significant source of cadmium, lead, and toxic elements, which are absorbed into the human organism. In this context, the aim of this study was to investigate in vitro the presence of toxic elements, cadmium, and lead deriving from cigarette smoke in the resin composite, dentine, and dental enamel. Eight cylindrical specimens were fabricated from resin composite, bovine enamel, and root dentin fragments that were wet ground and polished with abrasive paper to obtain sections with 6‐mm diameter and 2‐mm thickness. All specimens were exposed to the smoke of 10 cigarettes/day during 8 days. After the simulation of the cigarette smoke, the specimens were examined with scanning electron microscopy (SEM) and the energy‐dispersive X‐ray analysis. In the photomicrographic analysis in SEM, no morphological alterations were found; however, the microanalysis identified the presence of cadmium, arsenic, and lead in the different specimens. These findings suggest that the deposition of these elements derived from cigarette smoke could be favored by dental structures and resin composite. Microsc. Res. Tech., 2010. © 2010 Wiley‐Liss, Inc. 相似文献
105.
Corredera L Bayarri S Pérez-Arquillué C Lázaro R Molino F Herrera A 《Journal of food protection》2011,74(10):1692-1699
An analytical procedure based on solid-phase extraction, using ethyl acetate as the elution solvent, and high-performance liquid chromatography with fluorescence and diode array detection was developed for the identification and quantification of polycyclic aromatic hydrocarbons (PAHs) in honey. The method has been optimized and validated in accordance with Commission Regulation 333/2007 and Commission Decision 2002/657/EC. This method allows the identification of the 15 PAHs that should be monitored in food matrices, as proposed in 2002 by the Scientific Committee on Food and later by the European Union in the Commission Recommendation 2005/108/EC, because of their genotoxic and carcinogenic properties. The results of the validation study were in agreement with quality criteria described in European legislation in terms of sensitivity, accuracy, and ruggedness, and the method was applied to the analysis of 42 honey samples (21 from Spain and 21 from other regions). The honey samples were not contaminated by PAHs at detectable levels and thus could be marketed without health risk. 相似文献
106.
The ability of nerve cells to receive up to several thousands of synaptic inputs from other neurons provides the anatomical basis for information processing in the vertebrate brain. The formation of functional synapses involves selective clustering of neurotransmitter receptors at presumptive postsynaptic regions of the neuronal plasma membrane. Receptor-associated proteins are believed to be crucial for this process. In spinal neurons, synaptic targeting of the inhibitory glycine receptor (GlyR) depends on the expression of the anchoring protein gephyrin. Here we show that the competitive GlyR antagonist strychnine and L-type Ca2+-channel blockers inhibit the accumulation of GlyR and gephyrin at postsynaptic membrane areas in cultured rat spinal neurons. Our data are consistent with a model in which GlyR activation that results in Ca2+ influx is required for the clustering of gephyrin and GlyR at developing postsynaptic sites. Similar activity-driven mechanisms may be of general importance in synaptogenesis. 相似文献
107.
108.
Jos L Tambosi Michele Di Domenico Waldir N Schirmer Humberto J Jos Regina de FPM Moreira 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2006,81(8):1426-1432
A Fenton‐like process, involving oxidation and coagulation, was evaluated for the removal of odorous compounds and treatment of a pulp and paper wastewater. The main parameters that govern the complex reactive system [pH and Fe(III) and hydrogen peroxide concentrations] were studied. Concentrations of Fe(III) between 100 and 1000 mg L?1 and of H2O2 between 0 and 2000 mg L?1 were chosen. The main mechanism for color removal was coagulation. The maximum COD, color and aromatic compound removals were 75, 98 and 95%, respectively, under optimal operating conditions ([Fe(III)] = 400 mg L?1; [H2O2] = 500–1000 mg L?1; pH = 2.5; followed by coagulation at pH 5.0). The biodegradability of the wastewater treated increased from 0.4 to 0.7 under optimal conditions and no residual hydrogen peroxide was found after treatment. However, partially or non‐oxidized compounds present in the treated wastewater presented higher acute toxicity to Artemia salina than the untreated wastewater. Based on the optimum conditions, pilot‐scale experiments were conducted and revealed a high efficiency in relation to the mineralization of organic compounds. Terpenes [(1S)‐α‐pinene, β‐pinene, (1R)‐α‐pinene and limonene] were identified in the wastewater and were completely eliminated by the Fenton‐like treatment. Copyright © 2006 Society of Chemical Industry 相似文献
109.
Competition has been studied as something to be averted, yet rarely has it been asked what processes may be involved in successful competition. The authors tested whether more accurate modeling of an adversary can assist competitive success. Pairs played a zero-sum game with no specific skill component over 40 trials. The authors measured the relative accuracy of the players' second-order model (i.e., what I think about my opponent: R2MA) and third-order model (i.e., what I think my opponent thinks of me: R3MA), using responses to adjectives indicating personality traits. Performance correlated with both R3MA and having a better strategy (i.e., a better distribution of responses), but these variables contributed separately to performance variance. However, R2MA did not correlate with performance. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
110.
W. Jack Lackey John A. Hanigofsky Garth B. Freeman Regina D. Hardin Ajit Prasad 《Journal of the American Ceramic Society》1995,78(6):1564-1570
The feasibility of preparing small-diameter, high-strength, thermally stable silicon carbide fiber tows by the continuous chemical vapor deposition (CVD) of SiC onto carbon fiber tows was experimentally evaluated. Calculations of bending stresses and stresses caused by thermal expansion mismatch between the substrate and coating were used to evaluate the influence of coating thickness and substrate fiber diameter and type. Statistically designed and analyzed processing studies quantitatively showed the influence of key CVD process variables (temperature, pressure, and flow rates of CH3 SiCl3 and H2 ) on fiber attributes such as coating thickness and uniformity, surface roughness, percent agglomeration, and strength. Emphasis was given to conceiving and evaluating various fiber spreading devices in order to enhance coating uniformity and to minimize filament agglomeration within a tow. Uniform coatings and fiber tensile strengths as high as 4 GPa were achieved. 相似文献