Isolation of Phosphate-Solubilizing Fungi from Phosphate Mines and Their Effect on Wheat Seedling Growth

Three phosphate-solubilizing fungi, identified as Penicillium expansum, Mucor ramosissimus, and Candida krissii, were isolated from phosphate mines (Hubei, People’s Republic of China) and characterized. All the isolates demonstrated diverse levels of phosphate-solubilizing capability in National Botanical Research Institute’s phosphate growth medium containing rock phosphate as sole phosphate source. Acidification of culture medium seemed to be the main mechanism for rock phosphate solubilization. Indeed, citric acid, oxalic acid, and gluconic acid were shown to be present in the culture medium inoculated with these isolates. Moreover, the isolates produced acid and alkaline phosphatases in culture medium, which may also be helpful for RP solubilization. A strong negative correlation between content of soluble phosphorus and pH (r = – 0.89; p < 0.01) in culture medium was observed in this study. All the isolates promoted growth, soil available phosphorus, phosphorus, and nitrogen uptake of wheat seedling in field soil containing rock phosphate under pot culture conditions, thus demonstrating the capability of these isolates to convert insoluble form of phosphorus into plant available form from rock phosphate, and therefore hold great potential for development as biofertilizers to enhance soil fertility and promote plant growth.     

Fabrication of silicon oxycarbide fibers from alkoxide solutions along the sol–gel process

Spinnable solutions are obtained in the sol–gel system of tetraethoxide (TEOS, Si(OC₂H₅)₄) and vinyltrimethoxysilane (VTMS, CH₂=CHSi(OCH₃)₃) under aqueous condition (water) with acid catalysts (HNO₃ and HCl). Polysiloxane (PSO) fibers are drawn from the solution and characterized by spectroscopic and structural analyses. ²⁹Si-nuclear magnetic resonance NMR) spectral analysis of the PSO fiber indicates the incorporation of atomic carbon in the silica network. ¹³C-NMR analysis shows the existence of considerable amount of hydroxyl groups in the PSO fiber. The spinnablity of the solution is studied by varying the mole ratios of the alkoxides, solvents and catalysts as well as precursor chemistries. The amount of water and catalysts are found to be important for the attaining of a spinnable state in the solution. SiOC fibers are obtained after pyrolysis of the PSO fibers with a high ceramic yield (88 wt%). The high ceramic yield attributes to the incorporation of vinyl-groups in the gel fiber that enhances crosslinking during pyrolysis. The SiOC fiber has a tensile strength of 776 MPa and electrical conductivity of 3.6 × 10⁻⁴ S/m.     

两两NQD列加权和的安全收敛性

本文研究两两NQD系加权和的完全收敛性，证明了一般双下标加权系数的加权部分和的完全收敛性，改进了吴群英（2002）的结果。     

Two novel methods for vibration diagnosis to characterize non-linear response

Poincaré maps have been proved to be a valuable tool in the analysis of non-linear dynamical systems, which usually reduce a continuous phase flow into a two-dimensional discrete map. However, they may be inconvenient for reflecting some characteristics of the system response. In this paper, two novel methods, using the period sampling peak-to-peak value (PSP) diagram and the modified Poincaré map, are presented for characterizing different types of non-linear response. These two methods take advantage of some parameters of the response, such as the peak-to-peak value within an exterior excitation period and the mean value of the displacement. In the PSP diagram method, a two-dimensional graph is plotted by taking the peak-to-peak value as ordinate and the sequential periodically sampling number as abscissa. On the other hand, the modified Poincaré map takes the mean value of the velocity within an exterior excitation period as ordinate and the relevant mean value of the displacement as abscissa. The non-linear responses of a Duffing system, a pendulum with circular motion support and an oscillating circuit are studied by these methods. We also studied the intermittent chaos of the Lorenz system by the PSP diagram method. The PSP diagram is a set of mapping points, which form: a straight line for a one-period response; multi-straight lines for a multi-period response; orderly periodic curves for a quasi-period response; long lines interrupted by transitoriness confusion points for intermittent chaos; and totally out-of-order points for chaos. The figures for the modified Poincaré maps for the period, multi-period, quasi-period responses and chaos are almost identical to those for the Poincaré maps, but the modified maps take more sampling points and can reflect the mean values of the responses. Some numerical results are given based on these methods to show their efficiency in distinguishing different non-linear responses.     

半导体激光器纵向泵浦准连续Cr∶LiSAF激光器的实验研究

用波长为653.2nm的半导体激光器实现了纵向泵浦Cr∶LiSAF激光器的准连续运转，晶体平均吸收功率为140mW时获得激光输出，在LD最大输出功率范围内，晶体平均吸收功率为680mW时，可获得最大平均输出功率32mW，斜效率5.6%.     

血管紧张素转换酶与抑制肽结合模式的分子动力学研究

应用分子模拟方法研究了血管紧张素转换酶(Angiotensin-converting enzyme,ACE)C端结构域(C-domain)与两种抑制肽(RIGLF/AHEPVK)的结合机制,预测了两个体系的结合模式,提出在C-domain-RIGLF中His353,Asp377,Asp453,Phe457,His513,Tyr523和Phe527为RIGLF主要结合残基,而在C-domainAHEPVK中Gln281,His353,Ser355,Glu384,Lys511,His513和Tyr523等残基起关键作用.应用结合自由能计算比较了两个体系的结合能力,结果表明,RIGLF和AHEPVK均与C-domain活性位点残基存在较强作用,且AHEPVK对C-domain的结合能力较强,与实验结果一致.