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1.
The state of the surface of n-GaAs crystals upon high-vacuum microwave plasmachemical (HVMWPC) etching in various gas mixtures and the influence of the semiconductor surface condition on the photoelectric characteristics of related metal-semiconductor-metal structures with double Schottky barrier (MSMDSB structures) are investigated. Dependence of the HVMWPC etching rate of the GaAs surface on the gas mixture composition and substrate temperature is determined. It is shown that the HVMWPC etching regime strongly influences the photoelectric properties of MSMDSB structures: the treatment can lead to either growth or drop in photosensitivity of the samples. Optimum etching regimes are established for which good semiconductor surface quality and high photosensitivity of the MSMDSB structures are retained at a high etching rate. 相似文献
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Robert G Clyde James L Bown Ted R Hupp Nikolai Zhelev John W Crawford 《Journal of the Royal Society Interface》2006,3(10):617-627
The cell cycle is implicated in diseases that are the leading cause of mortality and morbidity in the developed world. Until recently, the search for drug targets has focused on relatively small parts of the regulatory network under the assumption that key events can be controlled by targeting single pathways. This is valid provided the impact of couplings to the wider scale context of the network can be ignored. The resulting depth of study has revealed many new insights; however, these have been won at the expense of breadth and a proper understanding of the consequences of links between the different parts of the network. Since it is now becoming clear that these early assumptions may not hold and successful treatments are likely to employ drugs that simultaneously target a number of different sites in the regulatory network, it is timely to redress this imbalance. However, the substantial increase in complexity presents new challenges and necessitates parallel theoretical and experimental approaches. We review the current status of theoretical models for the cell cycle in light of these new challenges. Many of the existing approaches are not sufficiently comprehensive to simultaneously incorporate the required extent of couplings. Where more appropriate levels of complexity are incorporated, the models are difficult to link directly to currently available data. Further progress requires a better integration of experiment and theory. New kinds of data are required that are quantitative, have a higher temporal resolution and that allow simultaneous quantitative comparison of the concentration of larger numbers of different proteins. More comprehensive models are required and must accommodate not only substantial uncertainties in the structure and kinetic parameters of the networks, but also high levels of ignorance. The most recent results relating network complexity to robustness of the dynamics provide clues that suggest progress is possible. 相似文献
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This paper describes a new optoelectronic device—an optical transistor that provides power amplification of output visible
radiation. The optical transistor is structurally based on a metallized semiconductor plate with a microchannel gap in the
form of a planar Mach-Zehnder interferometer. A device of the light-light type is controlled by modulating the refractive
index in one arm of the interferometer.
Pis’ma Zh. Tekh. Fiz. 24, 17–21 (January 26, 1998) 相似文献
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Automation and Remote Control - The paper considers the problem of constructing a convex subset of the largest area in a nonconvex compact set on the plane as well as the problem of constructing a... 相似文献
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Elisabeth M. Haberl Thomas S. Weiss Georg Peschel Kilian Weigand Nikolai Khler Josch K. Pauling Jürgen J. Wenzel Marcus Hring Sabrina Krautbauer Gerhard Liebisch Christa Buechler 《International journal of molecular sciences》2021,22(10)
Hepatocellular carcinoma (HCC) still remains a difficult to cure malignancy. In recent years, the focus has shifted to lipid metabolism for the treatment of HCC. Very little is known about hepatitis B virus (HBV) and C virus (HCV)-related hepatic lipid disturbances in non-malignant and cancer tissues. The present study showed that triacylglycerol and cholesterol concentrations were similar in tumor adjacent HBV and HCV liver, and were not induced in the HCC tissues. Higher levels of free cholesterol, polyunsaturated phospholipids and diacylglycerol species were noted in non-tumorous HBV compared to HCV liver. Moreover, polyunsaturated phospholipids and diacylglycerols, and ceramides declined in tumors of HBV infected patients. All of these lipids remained unchanged in HCV-related HCC. In HCV tumors, polyunsaturated phosphatidylinositol levels were even induced. There were no associations of these lipid classes in non-tumor tissues with hepatic inflammation and fibrosis scores. Moreover, these lipids did not correlate with tumor grade or T-stage in HCC tissues. Lipid reprogramming of the three analysed HBV/HCV related tumors mostly resembled HBV-HCC. Indeed, lipid composition of non-tumorous HCV tissue, HCV tumors, HBV tumors and HBV/HCV tumors was highly similar. The tumor suppressor protein p53 regulates lipid metabolism. The p53 and p53S392 protein levels were induced in the tumors of HBV, HCV and double infected patients, and this was significant in HBV infection. Negative correlation of tumor p53 protein with free cholesterol indicates a role of p53 in cholesterol metabolism. In summary, the current study suggests that therapeutic strategies to target lipid metabolism in chronic viral hepatitis and associated cancers have to consider disease etiology. 相似文献
9.
Sergey V. Ushakov Alexandra Navrotsky Jean A. Tangeman Katheryn B. Helean 《Journal of the American Ceramic Society》2007,90(4):1171-1176
Aerodynamic levitation combined with laser heating was used to prepare melts in the HfO2 –La2 O3 (–Gd2 O3 ) systems. All melts crystallized upon quenching in oxygen. Hf2 La2 O7 pyrochlore and Gd0.5 Hf0.5 O1.75 fluorite phases were identified. Gd0.5 Hf0.5 O1.75 fluorite was transformed into the pyrochlore structure by annealing at 1450°C. Pyrochlore that crystallized from HfO2 - La2 O3 melts contained 31.6–34.2 mol% La2 O3 . The unit cell parameter increased linearly with La content from 10.736 to 10.789 Å. Drop solution calorimetric experiments were performed in 3Na2 O·4MoO3 melt at 702°C. The enthalpies of formation from the oxides for pyrochlore phases are −107.0±5.0 kJ/mol for Hf2 La2 O7 and −48.8±4.7 kJ/mol for Hf2 Gd2 O7 . The enthalpy of the pyrochlore–fluorite phase transition in Hf2 Gd2 O7 is 23.6±3.1 kJ/mol. 相似文献
10.
Development of monolithic catalysts with low noble metal content for diesel vehicle emission control
Yashnik S. A. Kuznetsov V. V. Ismagilov Z. R. Ushakov V. V. Danchenko N. M. Denisov S. P. 《Topics in Catalysis》2004,30(1-4):293-298
Topics in Catalysis - Monolith washcoated catalysts with potential for diesel emission control have been developed. Two types of catalysts have been prepared for further study: (1) MnO x supported... 相似文献