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排序方式: 共有206条查询结果,搜索用时 15 毫秒
201.
Skála T Tsud N Orti MÁ Menteş TO Locatelli A Prince KC Matolín V 《Physical chemistry chemical physics : PCCP》2011,13(15):7083-7089
The deposition of ceria on a preoxidized W(110) crystal at 870 K has been studied in situ by photoelectron spectroscopy and low-energy electron diffraction. Formation of an epitaxial layer of crystalline cerium tungstate Ce(6)WO(12)(100), with the metals in the Ce(3+) and W(6+) chemical states, has been observed. The interface between the tungsten substrate and the tungstate film consists of WO suboxide. At thicknesses above 0.89 nm, cerium dioxide grows on the surface of Ce(6)WO(12), favoured by the limited diffusion of tungsten from the substrate. 相似文献
202.
Holographic pixel super-resolution in portable lensless on-chip microscopy using a fiber-optic array
Bishara W Sikora U Mudanyali O Su TW Yaglidere O Luckhart S Ozcan A 《Lab on a chip》2011,11(7):1276-1279
We report a portable lensless on-chip microscope that can achieve <1 μm resolution over a wide field-of-view of ~ 24 mm(2) without the use of any mechanical scanning. This compact on-chip microscope weighs ~ 95 g and is based on partially coherent digital in-line holography. Multiple fiber-optic waveguides are butt-coupled to light emitting diodes, which are controlled by a low-cost micro-controller to sequentially illuminate the sample. The resulting lensfree holograms are then captured by a digital sensor-array and are rapidly processed using a pixel super-resolution algorithm to generate much higher resolution holographic images (both phase and amplitude) of the objects. This wide-field and high-resolution on-chip microscope, being compact and light-weight, would be important for global health problems such as diagnosis of infectious diseases in remote locations. Toward this end, we validate the performance of this field-portable microscope by imaging human malaria parasites (Plasmodium falciparum) in thin blood smears. Our results constitute the first-time that a lensfree on-chip microscope has successfully imaged malaria parasites. 相似文献
203.
In this study, steady-state laminar forced flow and heat transfer in a horizontal smooth trapezoidal duct having different corner angles were experimentally investigated in the Reynolds number range from 102 to 103. Flow is hydrodynamically fully developed and thermally developing under a uniform surface temperature condition. Based on the present experimental data of laminar flow in the thermal entrance region, new engineering correlations were presented for the heat transfer and friction coefficients for each corner angle. The results have shown that as the Reynolds number increases heat transfer coefficient increases but Darcy friction factor decreases. Also, it is observed that average Nusselt number increases while average Darcy friction factor decreases with increasing corner angle of the duct. 相似文献
204.
Cai Z Riedel H Thaw Saw NM Kütük O Mewis I Jäger H Knorr D Smetanska I 《Applied biochemistry and biotechnology》2011,164(4):443-453
Plant cell cultures provide a large potential for the production of secondary metabolites. Through the application of different
physical and chemical cell stress factors, we investigated the production of the secondary metabolites in plant cell cultures.
The effects of pulsed electric field (PEF) and ethephon on growth and secondary metabolism, particularly anthocyanins and
phenolic acids synthesis, were investigated by using suspension culture of Vitis vinifera L. cv. Gamay Fréaux as a model system. Anthocyanins were measured by spectrophotometer and extracellular phenolic acids were
determined by high-performance liquid chromatography. The compounds were identified by liquid chromatography–mass spectrometry
and nuclear magnetic resonance. After the treatments with PEF and ethephon, the concentrations of anthocyanins and phenolic
acids in cell culture were higher than in the control, without loss of biomass. The combination of PEF treatment and ethephon
improved secondary metabolites formation. Production levels of extracellular phenolic acids, 3-O-glucosyl-resveratrol were increased by PEF and ethephon treatments. The results show that PEF induced a defense response
of plant cells and may have altered the cell/membrane’s dielectric properties. PEF, an external stimulus or stress, is proposed
as a promising new abiotic elicitor for stimulating secondary metabolites biosynthesis in plant cell cultures. 相似文献
205.
Aleksandra Wypych-Puszkarz Onur Cetinkaya Jiajun Yan Ruslana Udovytska Jarosaw Jung Jacek Jenczyk Grzegorz Nowaczyk Stefan Jurga Jacek Ulaski Krzysztof Matyjaszewski Joanna Pietrasik Marcin Kozanecki 《Molecules (Basel, Switzerland)》2022,27(19)
Core−shell nanocomposites comprising barium titanate, BaTiO3 (BTO), and poly(methyl methacrylate) (PMMA) chains grafted from its surface with varied grafting densities were prepared. BTO nanocrystals are high-k inorganic materials, and the obtained nanocomposites exhibit enhanced dielectric permittivity, as compared to neat PMMA, and a relatively low level of loss tangent in a wide range of frequencies. The impact of the molecular dynamics, structure, and interactions of the BTO surface on the polymer chains was investigated. The nanocomposites were characterized by broadband dielectric and vibrational spectroscopies (IR and Raman), transmission electron microscopy, differential scanning calorimetry, and nuclear magnetic resonance. The presence of ceramic nanoparticles in core–shell composites slowed down the segmental dynamic of PMMA chains, increased glass transition temperature, and concurrently increased the thermal stability of the organic part. It was also evidenced that, in addition to segmental dynamics, local β relaxation was affected. The grafting density influenced the self-organization and interactions within the PMMA phase, affecting the organization on a smaller size scale of polymeric chains. This was explained by the interaction of the exposed surface of nanoparticles with polymer chains. 相似文献
206.
Öztürk Tuğçe Pınar Gelir Ali Keshtiban Nahid Aghabalapoor Yargı Önder Özdemir Onur B. Mucur Selin Pıravadılı Seçgin Alper 《Journal of Solid State Electrochemistry》2023,27(4):885-894
Journal of Solid State Electrochemistry - The motion of the ion pairs under the applied electric field is an important phenomenon in the storage properties of the capacitive devices. In this study,... 相似文献