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排序方式: 共有124条查询结果,搜索用时 15 毫秒
31.
Bedri Onur Kucukyiidirim Aysegul Akdogan Eker 《材料科学与工程:中英文B版...》2014,(12):353-357
Nowadays, it is vital to predict strength results of composites in advance of manufacturing process to reduce testing costs; especially in carbon nanotube (CNT) reinforced metal matrix composites. Therefore, compressive mechanical properties of fabricated CNT reinforced aluminum (AI) matrix composites are investigated and compared with the calculation results of dispersion based prediction models. First of all, CNT/6063 AI composites are fabricated by vacuum assisted infiltration of molten 6063 AI alloy into the CNT preform. Then, compressive mechanical properties of these composites are determined. Eventually, model calculations and experimental results are visualized by plotting comparison graphs. As a result, correlation between prediction models and experimental results are established and potential results of difference between these results are discussed. 相似文献
32.
Sule Erten Ela Maja Remskar Gozde Yurdabak Karaca Lutfi Oksuz Emre Uygun 《Particulate Science and Technology》2019,37(5):612-618
Modification of W5O14 and MoS2 nanostructures was carried out using 3,4-ethylenedioxythiophene monomer in a capacitively coupled, RF rotating plasma reactor. Raman spectroscopy and X-ray diffraction (XRD) measurements were used for structural characterization. The surface morphologies of nanomaterials were investigated using transmission electron microscopy. Polymer coated (W5O14/PEDOT, MoS2/PEDOT) and untreated (W5O14, MoS2) nanostructures were used as the counter electrode for dye-sensitized solar cells. Photovoltaic performances of W5O14/PEDOT and MoS2/PEDOT hybrid nanostructures were higher than those of W5O14 and MoS2 inorganic nanostructures. Our results indicate that plasma polymer coated W5O14 and MoS2 nanostructures of the device for cathode increase both its fill factor and its energy conversion efficiency. 相似文献
33.
Bing Wu Meng-Lin Yang Yan-Ci Yan Chong-Geng Ma Hong-Wu Zhang Mikhail G. Brik Miroslav D. Dramićanin Uygun V. Valiev Michal Piasecki 《Journal of the American Ceramic Society》2021,104(3):1489-1500
Elpasolite crystals are very important materials, both from the applied and fundamental points of view. Those elpasolites, which contain rare earth ions with a high atomic number Z, are very much suitable for the low-cost high-performance gamma-ray detection, applications in medicine, food industry, nuclear energy production, processing, and detection of nuclear proliferation. The thermal and structural stabilities are important parameters required for detecting applications, because the performance conditions for such devices are usually very harsh. Since it is widely believed that elpasolites may have even better detection properties, the lack of systematic studies on the elpasolites and thus the unavailability of reliable data on their physical properties and trends in their variation caused by chemical composition considerably hinders search for more efficient new materials. Therefore, to fill in this gap and provide with all essential information about a large number of elpasolites crystals, for the first time, the structural stability, elastic, vibrational, and electronic properties of 60 cubic elpasolite Cs2NaLnX6 (Ln = La, …, Lu, X = F, Cl, Br, I) crystals were consistently calculated in the framework of the same computational approach based on the density functional theory (DFT). Variation of all calculated parameters (such as the lattice constants, elastic constants, Debye temperature, normal vibrational modes frequencies, Mulliken effective charges, bond populations, and band gaps) across the considered groups of crystals was analyzed and several trends, which are important for the search and preparation of new stable materials with improved performance, were identified. 相似文献
34.
To establish en in vitro test method that can predict the drug release and dissolution behaviour of vaginal bioadhesive controlled release tablets, a system was developed and its appropriateness to the in situ conditions was examined. For this purpose, the dissolution rates of vaginal bioadhesive tablets were measured by three different methods. These were, USP dissolution apparatus two and a new vaginal dissolution tester (NVDT) which was developed by us with some modification of the vaginal tablet desentegration apparatus of BP 1988 and, testing in cow vaginas in situ. Four different bioadhesive tablet formulations were used being composed of the drug and the anionic polymer, polyacrylic acid (PAA) and the nonionic polymers, hydroxypropylmethyl cellulose (HPMC) and ethyIcellulose (EC). The release profiles of the in vitro and in situ methods were investigated and evaluated kinetically.
It was found that NVDT could be used to investigate the drug release from vaginal tablets. 相似文献
It was found that NVDT could be used to investigate the drug release from vaginal tablets. 相似文献
35.
36.
In this study, three medicinal and aromatic plants (Foeniculum vulgare, Malva sylvestris L. and Thymus vulgaris) were dried in a pilot scale gas engine driven heat pump drier, which was designed, constructed and installed in Ege University, Izmir, Turkey. Drying experiments were performed at an air temperature of 45 °C with an air velocity of 1 m/s. In this work, the performance of the drier along with its main components is evaluated using exergy analysis method. The most important component for improving the system efficiency is found to be the gas engine, followed by the exhaust air heat exchanger for the drying system. An exergy loss and flow diagram (the so-called Grassmann diagram) of the whole drying system is also presented to give quantitative information regarding the proportion of the exergy input dissipated in the various system components, while the sustainability index values for the system components are calculated to indicate how sustainability is affected by changing the exergy efficiency of a process. Gas engine, expansion valve and drying ducts account for more than 60% amount of exergy in the system. The exergetic efficiency values are in the range of 77.68–79.21% for the heat pump unit, 39.26–43.24% for the gas engine driven heat pump unit, 81.29–81.56% for the drying chamber and 48.24–51.28% for the overall drying system. 相似文献
37.
Specific features of Eu~(3+) and Tb~(3+) magnetooptics in gadolinium-gallium garnet (Gd_3Ga_5O_(12))
Uygun V. Valiev John B. Gruber 付德君 Vasiliy O. Pelenovich Gary W. Burdick Mariya E. Malysheva 《中国稀土学报(英文版)》2011,(8)
We reported magnetooptical properties of Eu3+(4f(6)) and Tb3+(4f(8)) in single crystals of Gd3Ga5O12 (GGG), Y3Ga5O12 (YGG), and Eu3+(4f(6)) in Eu3Ga5O12 (EuGG) for both ions occupying sites of D2 symmetry in the garnet structure. Absorption, luminescence, and magnetic circular polarization of luminescence (MCPL) spectra of Tb3+ in GGG and YGG and absorption and magnetic circular dichroism (MCD) of Eu3+ in EuGG were studied. The data were obtained at 85 K and room temperature (RT). Magnetic susceptibility of... 相似文献
38.
Ground Motion Prediction Equations (GMPEs) are empirical relationships which are used for determining the peak ground response at a particular distance from an earthquake source. They relate the peak ground responses as a function of earthquake source type, distance from the source, local site conditions where the data are recorded and finally the depth and magnitude of the earthquake. In this article, a new prediction algorithm, called Conic Multivariate Adaptive Regression Splines (CMARS), is employed on an available dataset for deriving a new GMPE. CMARS is based on a special continuous optimization technique, conic quadratic programming. These convex optimization problems are very well-structured, resembling linear programs and, hence, permitting the use of interior point methods. The CMARS method is performed on the strong ground motion database of Turkey. Results are compared with three other GMPEs. CMARS is found to be effective for ground motion prediction purposes. 相似文献
39.
The purpose of this work is to assess the radical scavenging activity, acetylcholinesterase inhibition, and proline content of an aqueous extract from wild pistachio (Pistacia atlantica Desf.) leaves. The effect of aqueous extract on superoxide radical scavenging, hydroxyl radical scavenging, N,N-dimethyl-1,4-phenylendiammoniumdichloride (DMPD·+) radical scavenging, ABTS·+ radical scavenging, nitric oxide scavenging, and β-carotene bleaching activities was examined. This study found that the aqueous extract possesses considerable amounts of flavonoids (33.52±2.04 μg catechin equivalents/mg of extract). The effect of this extract in scavenging activity of hydroxyl radical and DMPD·+ was significantly better than that of ascorbic acid and butylated hydroxyanisole (BHA). The effect of the extract in superoxide and ABTS·+ was significantly similar than that of tested standard antioxidants. The proline content of the extract was found to be 0.54±0.01 μg proline/mg of extract. Aqueous extract of P. atlantica inhibited acetylcholinesterase activity effectively with IC50 value of 58.05±0.12 μg/mL. 相似文献
40.
Summary Polytetrahydrofuran macroinimers were synthesized by means of cationic polymerization of tetrahydrofuran, initiated by azo-oxocarbenium salt, followed by termination with methacrylate anion. The macroinimers were characterized by 1H-NMR analysis and GPC measurements. Self polymerization of macroinimers and copolymerization with methyl methacrylate (MMA) yielded crosslinked and soluble branched block copolymers depending on the MMA concentration. 相似文献