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排序方式: 共有408条查询结果,搜索用时 15 毫秒
401.
TiN/TaN multilayer coatings exhibit excellent mechanical properties when compared to single layer nitride coatings. In this study, TiN/TaN multilayer coatings were deposited on Mo-alloy and W-alloy substrates by CFUBMS. The structural and mechanical properties of coatings were analysed using XRD, EDS, SEM and a micro-hardness tester, respectively. To determine the adhesion and fatigue behaviour of the coatings were performed a scratch test in two modes that a standard mode with progressive loading and sliding-fatigue multimode operation with unidirectional sliding, respectively. A microscope was used to characterize adhesion and fatigue failures. The structural, mechanical, adhesion and fatigue properties of TiN/TaN multilayer coatings significantly changed depending on the substrate. 相似文献
402.
Saraswathy Gnanasundaram Srinivasan Kannan Mohan Ranganathan Bhabendra Nath Das Asit Baran Mandal 《Polymer-Plastics Technology and Engineering》2015,54(15):1585-1595
The aim of this research work is to prepare biodegradable polyurethane composites and study their physical, mechanical, thermal, and biodegradation properties. Rigid biodegradable polyester-based polyurethane was synthesized by reacting excess of isocyanate with poly(ε-caprolactone)diol to obtain prepolymer which was then reacted with chain extender. The polyurethane composites are prepared with nanoclay and titanium(IV)oxide nanopowder in different concentrations, and polyurethane containing 2% w/w of nanopowder had shown better properties. Biodegradation studies showed that the developed polyurethane materials when used as shoe soles will retain their strength while storage and use, but will decompose only after disposal into the environment. 相似文献
403.
Monika Barteková Petra ?imon?íková Mária Fogarassyová Monika Ivanová ?udmila Okruhlicová Narcisa Tribulová Ima Dovinová Miroslav Baran?ík 《International journal of molecular sciences》2015,16(4):8168-8185
Quercetin (QCT) is flavonoid that possesses various biological functions including anti-oxidative and radical-scavenging activities. Moreover, QCT exerts some preventive actions in treatment of cardiovascular diseases. The aim of present study was to explore effects of prolonged administration of QCT on changes induced by repeated application of doxorubicin (DOX) in rat hearts. We focused on the ultrastructure of myocardium, matrix metalloproteinases (MMPs), biometric parameters, and apoptosis induction. Our aim was also to examine effects of QCT on ischemic tolerance in hearts exposed to chronic effects of DOX, and to determine possible mechanisms underlying effects of QCT. Our results showed that QCT prevented several negative chronic effects of DOX: (I) reversed DOX-induced blood pressure increase; (II) mediated improvement of deleterious effects of DOX on ultrastructure of left ventricle; (III) prevented DOX-induced effects on tissue MMP-2 activation; and (iv) reversed effects of DOX on apoptosis induction and superoxide dismutase inhibition. Moreover, we showed that rat hearts exposed to effects of QCT were more resistant to ischemia/reperfusion injury. Effects of QCT on modulation of ischemic tolerance were linked to Akt kinase activation and connexin-43 up-regulation. Taken together, these results demonstrate that prolonged treatment with QCT prevented negative chronic effects of DOX on blood pressure, cellular damage, MMP-2 activation, and apoptosis induction. Moreover, QCT influenced myocardial responses to acute ischemic stress. These facts bring new insights into mechanisms of QCT action on rat hearts exposed to the chronic effects of DOX. 相似文献
404.
Magnetic and Electrotransport Properties of the Anion-Deficient Manganites with Perovskite Structure
S. V. Trukhanov I. O. Troyanchuk A. V. Trukhanov H. Szymczak R. Szymczak M. Baran 《Journal of Low Temperature Physics》2005,139(3-4):461-478
The chemical phase content and microstructure as well as magnetic and magnetotransport properties for the doped anion-deficient La3+1-xSr2+xMn3+O2–3-x/2 orthomanganites have been experimentally studied. The high-quality anion-deficient ceramic with controlled chemical phase content and microstructure has been obtained from the parent stoichiometric one at the 800 C in vacuum. The average grain size is ~5 m. It is established that the samples in the region of 0 x 0.125 are O-orthorhombic perovskites whereas in the 0.175 x 0.30—rhombohedric. As doping level increases along with the oxygen vacancies number the samples in ground state undergo a transition from the antiferromagnet A-type (x=0) through the inhomogeneous magnetic state (0 < x 0.175 to the cluster spin glass one (0.175 < x 0.30. The temperature of magnetic moment freezing is ~ 45 K. All the samples are semiconductors and show considerable magnetoresistance over a wide temperature range with peak for x = 0.175 only. Fitting of the electrical resistivity to T–1 and T–1/4 realized. The concentration dependences of the activation energy, spontaneous magnetization, coercivity as well as magnetic transition temperatures for the anion-deficient La3+1-xSr2+xMn3+O2–3-x/2 ortomanganites have been established. Obtained experimental results are interpreted in terms of the oxygen vacancies, isotropic superexchange Mn3+-O–Mn3+ interactions and phase separation models. 相似文献
405.
Kyaw Thu Anutosh Chakraborty Bidyut Baran Saha Kim Choon Ng 《Applied Thermal Engineering》2013,50(2):1596-1602
Thermo-physical properties, surface characteristics and water vapor uptake capacity are key parameters in the selection of adsorbent for an adsorption desalination (AD) cycle. In the AD cycles, silica gel is used as adsorbent due to their high water vapor uptake capacity, reliability, repeatability and inexpensiveness as compared to other adsorbents. Three types of commercially available silica gels (Type-RD 2560,Type-A5BW and Type-A++) are investigated using a surface characteristic analyzer and their thermo-physical properties are evaluated using several analysis methods. The instrument used in this investigation employs the static volumetric method with liquid Nitrogen at 77 K as the filing fluid. The surface area of each adsorbent is studied using Brunauer–Emmett–Teller (BET) method whilst the pore size distribution (PSD) analysis is conducted with the Non-Local Density Functional Theory (NLDFT). It is observed that the Type-A++ silica gel (granular type) possesses the highest surface area of 863.6 m2/g amongst the three parent silica gels studied. It has a two-maxima or bimodal distribution pattern where the pore diameters are distributed mostly between 10 Å and 30 Å. Water vapor uptake capacity of silica gels are studied with water vapor dosage apparatus and the results show that the Type-A++ silica gel exhibits a highest equilibrium uptake at 537 cm3/g. These thermo-physical properties are essential for the design and the numerical simulation of AD cycles. 相似文献
406.
Activity and selectivity of selective CO oxidation in an H2-rich gas stream over Co3O4/CeO2/ZrO2, Ag/CeO2/ZrO2, and MnO2/CeO2/ZrO2 catalysts were studied. Effects of the metaloxide types and metaloxide molar ratios were investigated. XRD, SEM, and N2 physisorption techniques were used to characterize the catalysts. All catalysts showed mesoporous structure. The best activity was obtained from 80/10/10 Co3O4/CeO2/ZrO2 catalyst, which resulted in 90% CO conversion at 200°C and selectivity greater than 80% at 125°C. Activity of the Co3O4/CeO2/ZrO2 catalyst increased with increase in Co3O4 molar ratio. 相似文献
407.
Virtual Reality - This study analyses one of the most popular game engines and an audio middleware to reproduce sound according to sound propagation physics. The analysis focuses on the... 相似文献
408.
Intelligent Service Robotics - Mecanum wheeled robots can exhibit serious slippage problems because of the discontinuous contact between the wheels and the ground which negatively influences the... 相似文献