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71.
Suturin SM Sokolov NS Banshchikov AG Kyutt RN Sakata O Shimura T Harada J Tabuchi M Takeda Y 《Journal of nanoscience and nanotechnology》2011,11(4):2990-2996
Surface X-ray diffraction was applied to study structure of the fluorite-silicon interface forming upon epitaxial growth of CaF2 on Si(001) surface kept at 750 degrees C. Samples with CaF2 coverage of 1.5-4 (110)-monolayers were grown and in-situ characterized using synchrotron radiation. The 3 x 1-like surface reconstruction was observed in agreement with the previous studies by electron diffraction. Interestingly, a well pronounced splitting of the fractional x 1/3 reflections was revealed. This splitting was ascribed to the effect of antiphase domain boundaries in the row-like structure of the interface layer. The in-plane integrated intensities were used to reconstruct two-dimensional atomic structure of the high-temperature CaF2/Si(001) interface. 相似文献
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Potential release pathways, environmental fate, and ecological risks of carbon nanotubes 总被引:1,自引:0,他引:1
Petersen EJ Zhang L Mattison NT O'Carroll DM Whelton AJ Uddin N Nguyen T Huang Q Henry TB Holbrook RD Chen KL 《Environmental science & technology》2011,45(23):9837-9856
Carbon nanotubes (CNTs) are currently incorporated into various consumer products, and numerous new applications and products containing CNTs are expected in the future. The potential for negative effects caused by CNT release into the environment is a prominent concern and numerous research projects have investigated possible environmental release pathways, fate, and toxicity. However, this expanding body of literature has not yet been systematically reviewed. Our objective is to critically review this literature to identify emerging trends as well as persistent knowledge gaps on these topics. Specifically, we examine the release of CNTs from polymeric products, removal in wastewater treatment systems, transport through surface and subsurface media, aggregation behaviors, interactions with soil and sediment particles, potential transformations and degradation, and their potential ecotoxicity in soil, sediment, and aquatic ecosystems. One major limitation in the current literature is quantifying CNT masses in relevant media (polymers, tissues, soils, and sediments). Important new directions include developing mechanistic models for CNT release from composites and understanding CNT transport in more complex and environmentally realistic systems such as heteroaggregation with natural colloids and transport of nanoparticles in a range of soils. 相似文献
76.
Nikolai B. Gorev Inna F. Kodzhespirova Yury A. Kovalenko Evgeny N. Privalov Eugenio F. Prokhorov 《Microelectronics Journal》2001,32(12):979-982
The distribution of the electric field in planar film–substrate GaAs structures under backgating is considered. It is shown that backgating can make the film exhibit a long-length region of a low-gradient electric field exceeding the threshold of N-type negative differential mobility, the magnitude of negative differential mobility in this region being high enough. At values of the film doping density and film thickness typical of GaAs transferred-electron devices, this region can be as long as several tens of micrometers. The underlying physical mechanism is discussed. 相似文献
77.
Gregory Ya. Slepyan Nikolai A. Krapivin Sergey A. Maksimenko Akhlesh Lakhtakia Oleg M. Yevtushenko 《AEUE-International Journal of Electronics and Communications》2001,55(4):273-280
Scattering of electromagnetic cylindrical waves by an isolated, semi-infinite, open-ended, single-shell, zigzag carbon nanotube (CN) is considered in the optical regime. The CN is modeled as a smooth homogeneous cylindrical surface with impedance boundary conditions known from quantum-mechanical transport theory. An exact solution of the diffraction problem is obtained by the Wiener-Hopf technique. The differences between the scattering responses of metallic and semiconducting CNs are discussed. 相似文献
78.
The solution of problems on the determination of the stress state within the framework of flow theory with isotropic hardening has been obtained for a solid cylinder made of a material sensitive to the strain rate under conditions of proportional loading in tension combined with torsion. An analysis of the obtained expressions has been performed. The results of tensile tests with simultaneous torsion under conditions of superplasticity were used to plot a stress-strain diagram for titanium alloy VT9 with the use of the expressions for the stress intensity. 相似文献
79.
We have studied the kinetics of high-pressure sintering of a composite SiC(C) ― Si3N4 powder of a certain phase composition. We consider structuring and mechanical properties of the ceramics obtained on the basis of this powder.
相似文献80.
Rhodesherdeline Limage Elad Tako Nikolai Kolba Zhongyuan Guo Alba García‐Rodríguez Cludia N. H. Marques Gretchen J. Mahler 《Small (Weinheim an der Bergstrasse, Germany)》2020,16(21)
Nanoparticles (NPs) are used in food packaging and processing and have become an integral part of many commonly ingested products. There are few studies that have focused on the interaction between ingested NPs, gut function, the mucus layer, and the gut microbiota. In this work, an in vitro model of gastrointestinal (GI) tract is used to determine whether, and how, the mucus layer is affected by the presence of Gram‐positive, commensal Lactobacillus rhamnosus; Gram‐negative, opportunistic Escherichia coli; and/or exposure to physiologically relevant doses of pristine or digested TiO2 NPs. Caco‐2/HT29‐MTX‐E12 cell monolayers are exposed to physiological concentrations of bacteria (expressing fluorescent proteins) and/or TiO2 nanoparticles for a period of 4 h. To determine mucus thickness and composition, cell monolayers are stained with alcian blue, periodic acid schiff, or an Alexa Fluor 488 conjugate of wheat germ agglutinin. It is found that the presence of both bacteria and nanoparticles alter the thickness and composition of the mucus layer. Changes in the distribution or pattern of mucins can be indicative of pathological conditions, and this model provides a platform for understanding how bacteria and/or NPs may interact with and alter the mucus layer. 相似文献