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A CO/sub 2/ laser (approx.0.5 kJ energy, 70 nsec pulse width) was focussed onto the end of an axially oriented, thick (35 to 350 .mu.) carbon fiber with or without a magnetic field present along the laser-fiber axis. We present evidence for axial-to-transverse enhancement of the CVI 182A (n = 3 .-->. 2) transition, which is correlated with the appearance of a population inversion between levels n = 3 and 2. For the B = 0 kG, zero field case, the maximum gain-length product of kl approx. =3 (k approx. =6 cm/sup -1/) was measured for a carbon fiber coated with a thin layer of aluminum (for additional radiation cooling). The results are interpreted in terms of fast recombination due mostly to thermal conduction from the plasma to the cold fiber core.

By means of the saturation shake-flask technique, the saturation solubility data of 3,3′-diaminodiphenyl sulfone in 14 monosolvents (n-propanol, N,N-dimethylformamide, methanol, ethanol, ethylene g...

Abstract Urban renewal has become a key issue all through China's Transitional Period. The social, economic, political factors, and their correlations have been seriously considered. However, the effects of outdoor pedestrian thermal comfort and fluid ventilation effects as well as the residence living conditions in old city districts under urban reconstruction should, to some extent, be paid closer attention to. As an example, take an old city district in Wuhan where a comprehensive mathematical model describing the fluid flow and heat transfer characteristics has been presented. Considering the influences of ambient crosswind, solar radiation, and natural convection and radiation heat transfer, numerical analysis based on the original layout has been executed. By analyzing the temperature and velocity distributions of the old city district, a new planned layout has been presented in this research. By comparison, some basic rules have been advanced to achieve favorable thermal comfort and flow ventilation effects.

We have observed significant differences in the response to ionizing radiation of two closely related human cells lines, and now compare the effects on these lines of both low and intermediate LET radiation. Compared to TK6, WTK1 has an enhanced X-ray survival, and is also more resistant to cell killing by alpha-particles. The hprt locus is more mutable in WTK1 than in TK6 by both X-rays and alpha-particles. WTK1 is also more mutable by alpha-particles than by X-rays at the hprt locus. X-ray-induced mutation at the heterozygous tk locus in WTK1 is about 25 fold higher than in TK6, while alpha-particle-induced mutation is nearly 50 fold higher at this locus. Also, the slowly growing tk- mutants, which comprise the majority of spontaneous and X-ray-induced tk- mutants of TK6, were not induced significantly by alpha-particles. Previously, we showed that TK6 has a reduced capacity for recombination compared with WTK1, and therefore, these results indicate that recombinational repair may contribute to both cell survival and mutation-induction following exposure to ionizing radiation. Such a mechanism may aid cell survival, but could also result in increased deleterious effects such as the unmasking of recessive mutations in cancer suppresser genes.

We present an extension of the B erenger Perfectly Matched Layer with additional terms and tunable coecien ts which introduce some asymmetry in the absorption rate. We show that the discretized version of the new PML oers superior absorption rates than the discretized standard PML under a plane wave analysis. Taking advantage of the high rates of absorption of the new PML, we have devised a new strategy for introducing the technique of Mesh Renemen t into electromagnetic Particle-In-Cell plasma simulations. We present the details of the algorithm as well as a 2-D example of its application to laser-plasma interaction in the context of fast ignition.

Abstract Ammonia oxidation experiments were conducted at high pressure (30 bar and 100 bar) under oxidizing and stoichiometric conditions, respectively, and temperatures ranging from 450 to 925 K. The oxidation of ammonia was slow under stoichiometric conditions in the temperature range investigated. Under oxidizing conditions the onset temperature for reaction was 850–875 K at 30 bar, while at 100 bar it was about 800 K, with complete consumption of NH3 at 875 K. The products of reaction were N2 and N2O, while NO and NO2 concentrations were below the detection limit even under oxidizing conditions. The data were interpreted in terms of a detailed chemical kinetic model. The rate constant for the reaction of the important intermediate H2NO with O2 was determined from ab initio calculations to be 2.3 × 102 T2.994 exp(−9510 K/T) cm3 mol−1 s−1. The agreement between experimental results and model work was satisfactory. The main oxidation path for NH3 at high pressure under oxidizing conditions is NH3 ⟶ + OH NH2 ⟶ + HO 2 , NO 2 H2NO ⟶ + O 2 HNO ⟶ + O 2 NO ⟶ + NH 2 N2. The modeling predictions are most sensitive to the reactions NH2 + NO = NNH + OH and NH2 + HO2 = H2NO + OH, which promote the ammonia consumption by forming OH radicals, and to NH2 + NO = N2 + H2O and NH2 + NO2 = N2O + H2O, which are the main chain-terminating steps.

Graphene has been used as an electrically tunable material for switchable devices. A large area fabrication of Al-doped ZnO/Al2O3/graphene/Al2O3/gold/silicon device was enabled by a spin-processible hydrophilic mono-layer graphene oxide. The graphene was obtained directly from graphene oxide during the atomic layer deposition without other extra steps. A significant shift of Raman frequency up to 360 cm−1 was observed from graphene in the fabricated device, indicating a structural change in graphene. The absorption from the device was tunable with a negative voltage applied on the Al-doped ZnO side. The generated absorption change was sustainable when the voltage was off and erasable when a positive voltage was applied. The sustainability of tuned optical property in the graphene under investigation can lead to a design of device with less power consumption and many other applications.