Temperature programmed desorption studies of deuterium passivated silicon nanocrystals

As grown silicon (Si) surfaces are known to reconstruct in order to reduce the number of dangling bonds. Surface reconstructions of hydride-terminated Si(1 0 0) and Si(1 1 1) surfaces have already been extensively studied using temperature programmed desorption (TPD). The surfaces of nanocrystals, are yet to be probed using TPD. Si nanocrystals less than 8 nm and ranging from 50 to 200 nm in diameter are grown on SiO₂ surfaces in an ultra high vacuum chamber and the as grown surfaces are exposed to atomic deuterium. Desorption spectra are interpreted using analogies to Si(1 0 0). TPD spectra show that that the nanocrystals surfaces are covered by a mix of monodeuteride, dideuteride and trideuteride species. Monodeuteride species can be isolated by selectively annealing away the dideuteride and trideuteride, monodeuteride and dideuteride species can be isolated by annealing away the trideuteride. The relative populations of the deuterides depend on particle size, and their manner of filling on nanoparticles differs from that for extended surfaces. Etching of the nanocrystal surface is observed during TPD, which is a confirmation of the presence of trideuteride species on the nanocrystal surface.     

Research on improved reconstruction algorithms of optical tomography based on incomplete data

For reconstructing based on incomplete projection data, an improved max-entropy reconstruction algorithm is presented in this paper. Both least-square and max-entropy are used in this algorithm, and the penalize-function method is used in iterative processing. The numerical simulation of three different tested fields has been done. Compared with conventional three-dimensional reconstruction algorithms, this novel algorithm has a higher reconstruction precision as well as a better astringency, particularly in the case of easy tested field. For the reconstruction of asymmetric complicated tested field, it also has a good result if suitable projective direction and iterative times can be choosen. Finally, the application of this novel algorithm to diagnose the temperature field of arc plasma is presented.     

Temperature Sensitivity Control and Mechanical Stress Effect of Boron-Doped Long-Period Fiber Gratings

We will present in this work the quantitative analysis of the relationship between the doping concentrations of GeO 2 and B 2 O 3 in the core and cladding regions and the temperature sensitivity of the resonance wavelength shift in long-period fiber gratings (LPFGs). Based on this analysis, the temperature sensitivity was suppressed and enhanced to 0.002 nm/°C and 0.28 nm/°C, respectively. We will also discuss the effect of the residual mechanical stress on the optical and mechanical properties of LPFGs. In particular, we will present the measurement results of the dependence of the refractive index change and mechanical strength on the residual mechanical stress in the boron-doped fibers with depressed clad and matched clad.     

Effect of soft segment length on the thermal behaviors of fluorinated polyurethanes

Differential scanning calorimetry (DSC) and temperature modulated DSC (MDSC) have been applied to investigate the thermal behaviors of fluorinated polyurethanes (FPU), which were obtained using 2,2,3,3-tetrafluoro-1, 4-butanediol as the chain extender and based on various soft segments—polytetramethyl oxides (PTMO) with molecular weights of 650, 1000, 1400 and 2000. An exothermic peak and/or multiple melting endotherms were observed during the heating to melting temperature of soft and hard segments. Attributed to the simultaneous recrystallization and melting processes during heating, these features have been confirmed via MDSC, where an endotherm and an exotherm were noted in reversing and non-reversing components of the heat flow. Separating the non-reversing components from the reversing curves, the dependencies of polyurethane morphology on the length of the soft segment could be clarified using MDSC analysis. Soft segment lengthening significantly influences the morphology of soft segment domains in FPUs. The phase separation and crystallinity of the soft segment increased with its length. However, soft segment length exerted a minor influence on the dissociation temperature of the short-range ordered hard segment domain and on the melting temperature of hard segment crystals. Examination of the heats of melting based on the quasi-isothermal MDSC experiments indicated that the crystallinity of hard segment domains declined with increasing soft segment length.     

Entropy of the Universe and Standard Cosmology

By means of a variant approach to Standard Relativistic Cosmology, we hint that the entropy of the Universe is growing with t ^3/2, where t stands for time-coordinate. Then, the absolute temperature obeys Standard t ^−1/2-dependence. We make contact with our previous paper (Berman, Int. J. Theor. Phys., 2009), in the context of a Machian Universe; but we also consider the dependencies of the scale-factor and energy density, with time, as in Standard treatments.     

Monte Carlo simulation of the oscillatory behavior in partial oxidation of methane on nickel catalyst under nonisothermal conditions

The Monte Carlo method has been used to simulate the kinetic oscillations during partial oxidation of methane under nonisothermal conditions. The oscillatory behavior can be found with the selected parameters by using oxide formation and removal model. From the simulation, the temperature variation during the reaction synchronizes well with the oscillations of product formation rates, and also with the rates of oxide formation and reduction processes. Compared with the isothermal simulation results, the oscillations under the nonisothermal conditions are observed to have a slightly shorter period, lower maximum carbon coverage and higher nickel oxide coverage.     

低温液体输送过程中的参数计算与分析

首先分析了在稳定的单相流中液体温升和压力损失的计算方法 ,然后介绍了在稳定的两相流中如何计算流体的流量及出口液体的蒸气含量 ,最后对三种最常见的非稳定过程 :管路被冷却、填充盲支管以及打开阀门进行了分析 ,并分析了在这三种情况下如何确定压力波动的最大值     

微波场中化学试剂复介电系数及其温度特性

利用微波腔体微扰法，在３．０ＧＨｚ频点测定了二十一种常用化学试剂的复介电系数及其中几种典型试剂复介电系数的温变特性，在此基础上分析了不同极性化学试剂复介电参数温变的一些规律及其与分子结构间的内在联系。     

Altering efficiency of hydrophobic interaction chromatography by combined salt and temperature effects

The coupled effect of salt concentration and temperature on the retention behavior of proteins in hydrophobic interaction chromatography has been studied. The retention data of four model proteins, i.e., myoglobin, lysozyme, α-chymotrypsinogen and bovine serum albumin, have been acquired by isocratic experiments of chromatographic elution within the temperature range 5–25 °C at different ammonium sulphate concentrations in the mobile phase. The retention dependencies quantified as functions of the salt concentration and temperature have been exploited in designing the process of gradient elution. The propagation velocity of proteins under conditions of the step gradient of salt and temperature has been determined by use of the equilibrium theory. To evaluate kinetic effects accompanying the band propagation the transport-dispersive model has been employed. It has been shown that altering the propagation of the salt and temperature waves in a proper manner allows improving the separation efficiency. Moreover, manipulation of specific kinetics effects can also be exploited in protein separations.