NH_4ZnPO_4晶体结构Rietveld法精修

本文详细阐述用X射线粉末衍射及Rietveld法研究NH_4ZnPO_4晶体结构精修的实验方法。通过对85个结构模型参数、样品特性参数和仪器对衍射谱图的影响参数进行精修,进一步说明在精修过程中应注意的问题。该样品为单科晶系,其空间群为:P2_1,Z=4,精修后的晶胞参数为:a=8.7839(13)A,b=5.4432(21)A,c=8.9543(13)A,β=90.318(38)°,v=428.126(14)×10~(-10)m,Dx=2,830g/cm~3,品质因子:F(20)=27,M(20)=39,结构吻合因子:Rp=16.98％,Rwp=21.25％,R_(EXP)=16.18,S=1.3。     

光谱分析仪器的微机控制和数据处理系统

以日本理学Ｄ／ｍａｘ－Ａ,Ｂ,Ｃ系列Ｘ射线衍射仪和美国贝克曼ＤＵ－８８此外可见光分光光度计为例,详细介绍了这些仪器与ＰＣ联机的方法,以及硬件、软件和数据处理系统的开发工作。     

少掺量钢渣矿渣水泥的研究

在高掺量矿渣水泥中掺少量可看作低质熟料的钢渣,弥补由于熟料掺量少造成的碱性不足。当混合材的总量为６０％～６５％时,钢渣掺量控制在１５％～２０％左右,只需采用普通外加剂,就能够生产４２５水泥。工业性试验在太钢东山水泥厂进行。     

Biological hydrogen production by Clostridium acetobutylicum in an unsaturated flow reactor

A mesophilic unsaturated flow (trickle bed) reactor was designed and tested for H2 production via fermentation of glucose. The reactor consisted of a column packed with glass beads and inoculated with a pure culture (Clostridium acetobutylicum ATCC 824). A defined medium containing glucose was fed at a flow rate of 1.6 mL/min (0.096 L/h) into the capped reactor, producing a hydraulic retention time of 2.1 min. Gas-phase H2 concentrations were constant, averaging 74 +/- 3% for all conditions tested. H2 production rates increased from 89 to 220 mL/hL of reactor when influent glucose concentrations were varied from 1.0 to 10.5 g/L. Specific H2 production rate ranged from 680 to 1270 mL/g glucose per liter of reactor (total volume). The H2 yield was 15-27%, based on a theoretical limit by fermentation of 4 moles of H2 from 1 mole of glucose. The major fermentation by-products in the liquid effluent were acetate and butyrate. The reactor rapidly (within 60-72 h) became clogged with biomass, requiring manual cleaning of the system. In order to make long-term operation of the reactor feasible, biofilm accumulation in the reactor will need to be controlled through some process such as backwashing. These tests using an unsaturated flow reactor demonstrate the feasibility of the process to produce high H2 gas concentrations in a trickle-bed type of reactor. A likely application of this reactor technology could be H2 gas recovery from pre-treatment of high carbohydrate-containing wastewaters.     

点压渐进成形工具头运动轨迹形成方法研究

在普通渐进成形工艺的基础上,结合CNC成形锤渐进成形工艺特点,通过改变成形时的刀路轨迹,将二维等高线层上的点离散为正弦曲线上的插值点,使工具头在每一层上有规律地进行跳跃式运动,从而形成新的点压式渐进成形工艺。在数控渐进成形机床上,使用点压渐进成形工艺成形出65°定角度圆形口锥杯以及方形口锥杯。结果表明,使用这种方法修改后的运动轨迹能在数控渐进成形机床上实现加工,验证了点压式渐进成形工艺的可行性,并且可以用于不同形状的刀路轨迹。     

Gradient decrement of annealing time can improve PCR with fluorescent-labeled primers

The influences of fluorescence labeling on PCR amplification and T-RFLP analysis were examined by the analyses of a soil bacterial and archaeal community using both clone library and T-RFLP methods. The PCR amplification and microbial community structure patterns were compared among the primers labeled with and without fluorescent groups. PCR amplification was negatively affected by the labeling groups of the primers, which may be caused by the increment of primer molecular weight. It is known that thermodynamic movement of molecules will be slowed as molecular weight increased. Therefore it is understandable that the reaction of primer–DNA template hybridization will be inhibited with the fluorescent groups added to the primer(s). An effective “Gradient-Decreasing Annealing Time Program,” in which the annealing time was initially set long and reduced cycle by cycle, can improve PCR efficiency under comparable amplification specificity with the fluorescent-labeled primers. No significant negative impact was observed in the altered conditions.     

克拉玛依减排林区土地开发的效应

基于克拉玛依减排林区的土壤和地下水取样分析结果,应用生态系统服务价值的原理与方法,分析了克拉玛依减排林区的土地开发效应.结果表明土地开发已取得一定的正效应:已开发用地土壤有机质、有效N和速效K的质量分数均高于未开发用地,土地开发明显地改善了土壤的养分状况;土壤浅层总盐量降低67.5%,土壤盐渍化现象得到有效控制;林地生态系统服务价值高达1.5417×10⁹元/a.同时,土地开发也产生了一些负效应:地下水pH值、电导率、矿化度和全盐量均高于未开发用地,减排林区地下水化学特征不利于区域减排林效应的持续发挥;土壤有效P质量分数偏低,也不利于林区植被的生长.     

Phytosynthesis of nanoparticles: concept,controversy and application

Nanotechnology is an exciting and powerful discipline of science; the altered properties of which have offered many new and profitable products and applications. Agriculture, food and medicine sector industries have been investing more in nanotechnology research. Plants or their extracts provide a biological synthesis route of several metallic nanoparticles which is more eco-friendly and allows a controlled synthesis with well-defined size and shape. The rapid drug delivery in the presence of a carrier is a recent development to treat patients with nanoparticles of certain metals. The engineered nanoparticles are more useful in increasing the crop production, although this issue is still in infancy. This is simply due to the unprecedented and unforeseen health hazard and environmental concern. The well-known metal ions such as zinc, iron and copper are essential constituents of several enzymes found in the human system even though the indiscriminate use of similar other metal nanoparticle in food and medicine without clinical trial is not advisable. This review is intended to describe the novel phytosynthesis of metal and metal oxide nanoparticles with regard to their shape, size, structure and diverse application in almost all fields of medicine, agriculture and technology. We have also emphasized the concept and controversial mechanism of green synthesis of nanoparticles.     

基于生态系统服务价值的新疆后备土地资源质量评价

由于人口激增、气候变暖等因素导致的环境恶化、资源短缺及其各种影响成为当今研究的重点．土地资源的有限性对人类的生存和发展产生了制约作用，更加成为研究的热点之一．为了解决土地制约的问题，必须客观地对土地资源做出评价．利用新疆土地调查资料，以新疆土地资源的利用变化图，估算生态系统服务价值（ESV），总VES为7．13×10^8元．其中：农田VES为0．31×10^8元；林地VES为1．27×10^8元；草地VES为3．29×10^8元；水体VES为1．89×10^8元；未利用土地VES为0．37×10^8元．     

Image reconstruction for hybrid true-color micro-CT

X-ray micro-CT is an important imaging tool for biomedical researchers. Our group has recently proposed a hybrid "true-color" micro-CT system to improve contrast resolution with lower system cost and radiation dose. The system incorporates an energy-resolved photon-counting true-color detector into a conventional micro-CT configuration, and can be used for material decomposition. In this paper, we demonstrate an interior color-CT image reconstruction algorithm developed for this hybrid true-color micro-CT system. A compressive sensing-based statistical interior tomography method is employed to reconstruct each channel in the local spectral imaging chain, where the reconstructed global gray-scale image from the conventional imaging chain served as the initial guess. Principal component analysis was used to map the spectral reconstructions into the color space. The proposed algorithm was evaluated by numerical simulations, physical phantom experiments, and animal studies. The results confirm the merits of the proposed algorithm, and demonstrate the feasibility of the hybrid true-color micro-CT system. Additionally, a "color diffusion" phenomenon was observed whereby high-quality true-color images are produced not only inside the region of interest, but also in neighboring regions. It appears harnessing that this phenomenon could potentially reduce the color detector size for a given ROI, further reducing system cost and radiation dose.