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171.
Transparent ceramics for high-energy laser systems 总被引:1,自引:0,他引:1
Jas Sanghera Shyam BayyaGuillermo Villalobos Woohong KimJesse Frantz Brandon ShawBryan Sadowski R. MiklosColin Baker Michael HuntIshwar Aggarwal Fred KungDavid Reicher Stan PeplinskiAl Ogloza Peter LangstonChuck Lamar Peter VarmetteMark Dubinskiy Lewis DeSandre 《Optical Materials》2011,33(3):511-518
We demonstrate that transparent magnesium aluminate spinel ceramic possesses excellent thermo-optical properties, a record low absorption loss of 6 ppm/cm, and superior ruggedness which position it as a prime candidate for an exit window aperture for high energy laser systems, especially in hostile environments. We also demonstrate lasing with an efficiency of about 45% in transparent Yb3+:Y2O3 ceramic made by hot pressing high purity submicron co-precipitated powder. This paves the way forward for high power solid state lasers exploiting hosts with higher thermal conductivity than YAG. 相似文献
172.
173.
In this communication, an inexpensive underground shallow solar pond (SSP) water heater has been suggested, and its performance has also been studied in detail. An explicit analytical expression for temperature has been obtained. The effect of various parameters, viz duration of covering the system by insulation, duration of flow rate, flow rate, insulation thickness, water mass, etc. have also been discussed. Numerical calculations have been made for a typical cold day. 相似文献
174.
SE Galbraith A Tiwari MD Baron BT Lund T Barrett SL Cosby 《Canadian Metallurgical Quarterly》1998,72(12):10292-10297
There is evidence that CD46 (membrane cofactor protein) is a cellular receptor for vaccine and laboratory-passaged strains of measles virus (MV). Following infection with these MV strains, CD46 is downregulated from the cell surface, and consequent complement-mediated lysis has been shown to occur upon infection of a human monocytic cell line. The MV hemagglutinin (H) protein alone is capable of inducing this downregulation. Some wild-type strains of MV fail to downregulate CD46, despite infection being prevented by anti-CD46 antibodies. In this study we show that CD46 is also downregulated to the same extent by wild-type, vaccine, and laboratory-passaged strains of rinderpest virus (RPV), although CD46 did not appear to be the receptor for RPV. Expression of the RPV H protein by a nonreplicating adenovirus vector was also found to cause this downregulation. A vaccine strain of peste des petits ruminants virus caused slight downregulation of CD46 in infected Vero cells, while wild-type and vaccine strains of canine distemper virus and a wild-type strain of dolphin morbillivirus failed to downregulate CD46. Downregulation of CD46 can, therefore, be a function independent of the use of this protein as a virus receptor. 相似文献
175.
A thermal model has been developed for the heating of a greenhouse by using inner thermal curtain and natural flow of geothermal warm water through the polyethylene tube laid on its floor. The calculations were done for a typical production greenhouse with the climatic data in the central part of Argentina during winter period. From the energy conservations point of view, the greenhouse has been divided into three zones i.e., zone I (plants under thermal blanket), zone II (space under ceiling) and zone III (space between roof and ceiling). The model has been tested with the published experimental data of air temperatures in zone I and zone II of the greenhouse. From the results, it was observed that the temperatures of air surrounding the plant mass in zone I were maintained in the range of 14–23 °C during winter night and early morning resulting in the better growth of winter growing plants against the harmful freezing effects. The predicted values of air temperature both in zone I and zone II of the greenhouse obtained from the proposed model exhibited fair agreement with the published experimental values. 相似文献
176.
An indoor simulation study was carried out to evaluate heat and mass transfer relation for a semi-cylindrical metallic (opaque) condensing cover for higher yields at different operating temperatures under free and forced modes of operation. The objective is to design a distillation unit for higher yield for commercialization, particularly in India. Experiments have been conducted for the operating temperature range of 40°C to 80°C in a steady-state condition by using constant temperature bath. Data (temperature and yield) obtained from experimentation have been used to determine the values of coefficient C and n and, consequently, convective as well as evaporative heat transfer coefficients. It is inferred that a higher yield is obtained with an increase of temperature in the forced mode of operation as compared to that in the natural mode of operation due to a fast release of heat from the condensing cover. 相似文献
177.
178.
X-ray diffraction, transmission electron microscopy and differential scanning calorimetry were carried out to study the transformation
from amorphous to icosahedral/crystalline phases in the rapidly quenched Al50Cu45Ti5 and Al45Cu45Ti10 alloys. In the present investigation, we have studied the formation and stability of amorphous phase in Al50Cu45Ti5and Al45Cu45Ti10 rapidly quenched alloys. The DSC curve shows a broad complex type of exothermic overlapping peaks (288- 550†C) for Al50Cu45Ti5 and a well defined peak around 373†C for Al45Cu45Ti10 alloy. In the case of Al50Cu45Ti5 alloy amorphous to icosahedral phase transformation has been observed after annealing at 280†C for 73 h. Large dendritic
growth of icosahedral phase along with α-Al phase has been found. Annealing of Al50Cu45Ti5 alloy at 400†C for 8 h results in formation of Al3Ti type phase. Al45Cu45Ti10 amorphous alloy is more stable in comparison to Al50Cu45Ti5 alloy and after annealing at 400†C for 8 h it also transforms to Al3Ti type phase. However, this alloy does not show amorphous to icosahedral phase transformation. 相似文献
179.
The putative role(s) of a mechanically gated (MG) cation channel in Xenopus oocyte growth, maturation, fertilization and embryogenesis has been examined. Using a pharmacological approach, we have tested the effects of the MG channel blockers, gadolinium, gentamicin and amiloride on the above developmental events. Our results indicate that oocyte maturation, fertilization and early embryogenesis (up to the free-swimming stage 45) can proceed normally in the presence of concentrations of agents that either completely abolish (i.e., > or = 10 microM Gd3+) or partially block (i.e., 1 mM gentamicin) single MG channel activity as measured by patch-clamp recording. However, we also find that higher concentrations of Gd3+ (> or = 50 microM) can lead to an increased percentage (> 20%) of axis-perturbed embryos compared with control (< 1%) and that amiloride (0.5 mM) reduces the success of fertilization (from 100% to < 50%) and increases mortality (by approximately 75%) in developing embryos. Furthermore, we find that all three agents inhibit oocyte growth in vitro. However, their order of effectiveness (amiloride > gentamicin > Gd3+) is opposite to their order for blocking MG channels (Gd3+ > gentamicin > amiloride). These discrepancies indicated that the drugs effects occur by mechanisms other than, or in addition to, MG channel block. Our results provide no compelling evidence for the idea that MG channel activity is critical for development in Xenopus. This could mean that there are other mechanisms in the oocyte that can compensate when MG channel activity is blocked or that the protein that forms the channel can undergo additional interactions that result in a function insensitive to MG channel blockers. 相似文献
180.
Two folding and light solar ovens designed and constructed by Solar Box Cookers International (SBCI), Sacramento, U.S.A., have been studied experimentally. Furthermore, their performance is compared with standard two glass solar ovens designed by one of us (S.S.N.), in the climate of Costa Rica. According to our measurements, made with and without load, taken during 30 different days, both cardboard ovens are 15–25% less efficient than the conventional oven and, secondly, the improved SBCI oven is slightly better than the previous SBCI oven. 相似文献