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51.
Sergey V. Polyakov 《Journal of Modern Optics》2013,60(9):1045-1052
We review radiometric techniques that take advantage of photon counting and stem from the quantum laws of nature. We present a brief history of metrological experiments and review the current state of experimental quantum radiometry. 相似文献
52.
53.
Structure and Thermal Expansion of YSZ and La2Zr2O7 Above 1500°C from Neutron Diffraction on Levitated Samples
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Sergey V. Ushakov Alexandra Navrotsky Richard J. K. Weber Joerg C. Neuefeind 《Journal of the American Ceramic Society》2015,98(10):3381-3388
High‐temperature time‐of‐flight neutron diffraction experiments were performed on cubic yttria‐stabilized zirconia (YSZ, 10 mol% YO1.5) and lanthanum zirconate (LZ) prepared by laser melting. Three spheroids of each composition were aerodynamically levitated and rotated in argon flow and heated with a CO2 laser. Unit cell, positional and atomic displacement parameters were obtained by Rietveld analysis. Below ~1650°C the mean thermal expansion coefficient (TEC) for YSZ is higher than for LZ (13 ± 1 vs. 10.3 ± 0.6) × 10?6/K. From ~1650°C to the onset of melting of LZ at ~2250°C, TEC for YSZ and LZ are similar and within (7 ± 2) × 10?6/K. LZ retains the pyrochlore structure up to the melting temperature with Zr coordination becoming closer to perfectly octahedral. Congruently melting LZ is La deficient. The occurrence of thermal disordering of oxygen sublattice (Bredig transition) in defect fluorite structure was deduced from the rise in YSZ TEC to ~25 × 10?6/K at 2350°C–2550°C with oxygen displacement parameters (Uiso) reaching 0.1 Å2, similar to behavior observed in UO2. Acquisition of powder‐like high‐temperature neutron diffraction data from solid‐levitated samples is feasible and possible improvements are outlined. This methodology should be applicable to a wide range of materials for high‐temperature applications. 相似文献
54.
Sergey Kirpotin Yuriy Polishchuk Nataliya Bryksina Anna Sugaipova Alexei Kouraev Elena Zakharova 《The International journal of environmental studies》2013,70(5):603-623
Palsa peatlands occupy extensive areas in Western Siberia which is one of the most paludified flat lowlands of the world. Climatic changes in Western Siberia are more dramatic compared with other northern regions, and changes in palsa landscapes are more notable due to the severe continental climate here. The distribution, peculiarities and climate-indication capacities of West Siberian palsas are poorly known outside Russia. Thus, Western Siberia is one of the most interesting vast natural polygons for studying climate-driven changes in the landscapes. This paper aims to fill the gap in knowledge on West Siberian palsas and their capacity as a climate regulator. We present issues in distribution, typology and cyclic development of palsa peatlands and their actual climate-driven changes. We also analyse the role of palsas in the atmospheric cycle of CO2, and the hydrology of the palsa regions. 相似文献
55.
Michael Guerette Charles R. Kurkjian Sergey Semjonov Liping Huang 《Journal of the American Ceramic Society》2016,99(3):841-848
In situ Brillouin light scattering measurements with a spatial resolution of ~1 μm have been carried out to study the elastic moduli of silica glass fibers in a single two‐point bend experiment to nominal strains of 7% in both tensile and compressive regions. Such data are necessary in order to convert the failure strains obtained from two‐point bend experiments into failure stress. For the first time, the neutral axis shift in a bent silica glass fiber was observed in our measurements, with more of the fiber deforming in compression than in tension, resulting from the nonlinear elastic behavior of silica glass. Understanding the neutral axis shift will improve the accuracy of strain and stress calculations in bent fibers. This study shows that an expression including a fifth‐order term is required to capture both the minimum in compression and the maximum in tension in the strain‐dependent Young's modulus of silica glass. A stress versus strain relation over a broad range of compressive and tensile strains was established for silica glass in this study, which will significantly improve our understanding of its deformation behavior. 相似文献
56.
Studying of cellular interaction of hairpin‐like peptide EcAMP1 from barnyard grass (Echinochloa crusgalli L.) seeds with plant pathogenic fungus Fusarium solani using microscopy techniques
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57.
Lidia K. Kazantseva Sergey V. Rashchenko 《Journal of the American Ceramic Society》2014,97(6):1743-1749
Lightweight glass‐ceramic material similar to foam glass was obtained at 700°C–800°C directly from alkali‐activated silica clay and zeolitized tuff without preliminary glass preparation. It was characterized by low bulk density of 100–250 kg/m3 and high pore size homogeneity. Chemical processes occurring in alkali‐activated silica clay and zeolitized tuff were studied using X‐ray diffraction, thermal gravimetry, IR‐spectroscopy, and scanning electron microscopy. Pore formation in both compositions is caused by dehydration of hydrated sodium polysilicates (Na2O·mSiO2·nH2O), formed during alkali activation. Additional pore‐forming gas source in alkali‐activated zeolitized tuff is trona, Na3(CO3)(HCO3)·2H2O, formed during interaction between unbound NaOH and CO2 and H2O from air. Influence of mechanical activation of raw materials on chemical processes occurring in alkaline compositions was also studied. 相似文献
58.
Pavel P. Fedorov Vera Y. Proydakova Sergey V. Kuznetsov Valery V. Voronov Alexandr A. Pynenkov Konstantin N. Nishchev 《Journal of the American Ceramic Society》2020,103(5):3390-3400
The thermal analysis and X-ray powder diffraction studies of the Li2SO4–Na2SO4 system, including the high-temperature X-ray diffraction technique, have elucidated four phases of variable composition: three solid solutions based on the α-Li2SO4, α-Na2SO4, and α-LiNaSO4 high-temperature polymorphs, and a low-temperature β-LiNaSO4 phase. α-Na2SO4-Base solid solution disintegrates into two phases via a monotectoid phase transformation. It is quite probable that the monotectoid process is related to the conversion of the second-order phase transition to the first-order phase transition. 相似文献
59.
60.
Sergey Nickolayevich Mensov Gleb A. Abakumov Maxim V. Arsenyev Maxim A. Baten'kin Sergey A. Chesnokov Alexey N. Konev Yuri V. Polushtaytsev Margarita P. Shurygina Maria Yu. Zakharina 《应用聚合物科学杂志》2020,137(34):48976
The process of two-wave photopolymerization of a UV-curable composition with an optically degrading inhibitor is considered. By numerical simulation, it is shown that in the composition layer uniformly exposed to UV-radiation, such systems allow getting segments with different conversion under the action of inhomogeneous visible light. Based on the data on the photopolymerization kinetics of the compositions from triethylene glycol dimethacrylate (TEGDMA) and bisphenol-A glycidyl dimethacrylate (bis-GMA) with the UV-initiator 2,2-dimethoxy-2-phenylacetophenone (DMPA), it was shown that 3,5-di-tert-butyl-o-benzoquinone (35Q) with N,N-dimethylaniline (DMA, “Aldrich”, 99%) can serve as an inhibitor that degrades under action of visible radiation. Combining inhomogeneous visible light generated with a conventional DLP-projector and uniform UV-radiation of LED (365 nm) the two-wave lithographic process was implemented to create polymeric 2D-structures in 20 μm layer of the compositions from TEGDMA (70)/bis-GMA (30)/DMPA (0.05 wt%)/35Q (0.5 wt%)/DMA (1 wt%). 相似文献