Bio-conjugation of CaF2:Eu/chitosan nanoparticles with BSA and photoluminescent properties

CaF₂:Eu nanoparticles capped with chitosan and bio-conjugation of CaF₂:Eu/chitosan nanoparticles with bovine serum albumin (BSA) were synthesized via microemulsion method. As a surfactant, chitosan was employed to cap the nanoparticles during the synthesis process and provided functional groups, such as amino group for further bio-conjunction with BSA. CaF₂:Eu and CaF₂:Eu/chitosan–BSA nanoparticles were characterized by means of X-ray powder diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), ultraviolet spectrophotometer (UV), infrared spectrophotometer (IR) and photoluminescence spectrophotometer (PL). The XRD results indicated that the CaF₂:Eu and CaF₂:Eu/chitosan-BSA nanoparticles have crystallized well and the average sizes were about 16 and 19 nm, respectively. Images of FE-SEM showed that the average grain sizes of the CaF₂:Eu and bio-conjunction of CaF₂:Eu/chitosan nanoparticles with BSA were about 19 and 20 nm. The patterns of UV spectra and IR spectra showed that BSA was linked to CaF₂:Eu/chitosan nanoparticles. In the emission spectrum of the CaF₂:Eu/chitosan–BSA nanoparticles, characteristic emission peaks of Eu³⁺ within the wavelength ranging from 500 to 700 nm were observed, corresponding to the transitions from the excited ⁵D₀ levels to ⁷F_J levels. This confirmed that the Eu³⁺dopant ion is located in a Ca²⁺ crystal site with Td symmetry.     

4-硝基-2,3,5-三甲基吡啶-N-氧化物的合成

对 4 硝基 2 ,3,5 三甲基吡啶 N 氧化物的合成工艺进行了研究和改进。以 2 ,3,5 三甲基吡啶为原料 ,利用质量分数为 30 %的双氧水氧化 ,中间体粗品不经高真空精馏分离直接进行硝化反应 ,用质量分数为 6 5 %的硝酸代替发烟硝酸 ,使二步反应在一个容器中进行 ,简化了设备和操作。硝化反应的最佳反应条件为 :反应温度 80℃ ;反应时间 6h。产品的合成总收率高达95 % ,4 硝基 2 ,3,5 三甲基吡啶 N 氧化物的质量分数≥ 98% (高效液相色谱法 ) ,产品结构经IR ,1HNMR确证。     

飞航导弹子母弹对机场跑道封锁概率研究

针对飞航导弹子母弹打击机场跑道，建立了子母弹抛撒的椭圆散布模型．考虑子母弹精度的影响，研究了飞航导弹子母弹封锁机场跑道的概率，并与弹道导弹子母弹做了比较．分析了散布区域大小、形状和进入角对跑道失效率的影响，为武器系统设计和作战使用提供参考．     

Experimental and numerical study on aerodynamic noise of outdoor unit of room air conditioner with different grilles

The aerodynamic and aeroacoustic performances of outdoor unit with two different types of grille have been investigated in present study. Experimental results indicate that the grille sharp will affect the flow rate and increase broadband noise level of outdoor unit. Based on noise generation mechanism and CFD simulation, vortex shedding noise model and inlet turbulence noise model are adopted to predict the broadband noise level of outdoor unit. When vortex shedding noise is concerned, the wake parameters should be calculated at 3 mm downstream of grille to achieve good accuracy. Inlet turbulence noise is generated from the interaction between blade wake and the grille, and plays less important role in present outdoor unit configuration. In comparison with experimental results, it is shown that the broadband noise prediction method could provide reasonable accuracy and the error between prediction and experiment is less than 1 dBA.     

In vivo study of porous strontium-doped calcium polyphosphate scaffolds for bone substitute applications

The purpose of this study was to investigate in vivo biocompatibility and osteogenesis as well as degradability of the porous strontium-doped calcium polyphosphate (SCPP) scaffolds as a biomaterial for bone substitute applications. The evaluation was performed on a rabbit model over a period of 16 weeks by histology combined with image analysis, X-ray microradiography and immunohistochemistry methods. The histological and X-ray microradiographic results showed that the SCPP scaffold exhibited good biocompatibility and extensive osteoconductivity with host bone. Moreover, a significant more bone formation was observed in the SCPP group compared with that in the CPP group, especially at the initial stage after implantation. New bone volumes (NBVs) of the SCPP group determined at week 4, 8 and 16 were 14, 27 and 45%, respectively. Accordingly, NBVs of the CPP group were 10, 19 and 40%. Immunohistochemical results revealed that both the expression of collagen type I and bone morphogenetic proteins in the SCPP group were higher than that in the CPP group, which might be associated with the release of strontium ions during the implantation. In addition, during 16 weeks implantation the SCPP scaffold exhibited similar degradability with the CPP scaffold in vivo. Both scaffolds showed the greatest degradation rate for the first 4 weeks, and then the degradation rate gradually decreased. The results presented in this study demonstrated that SCPP scaffold can be considered as a biocompatible material, making it attractive for bone substitute application purposes.     

Agriculture and food quality and safety certification agencies in four Chinese cities

Investigations of certification agencies were conducted in four Chinese cities: Guangzhou, Shenzhen, Hangzhou and Qingdao. Based on an analysis of the data and information obtained, the status and character of agro-food certification in China were assessed. The main obstacle for development of agro-food certification was identified as the lack of market acceptance for it. In conclusion, the paper provides some suggestions for improving agro-food certification in China.     

Experimental study on the single event latchup simulated by a pulse laser

This paper introduces major characteristics of the single event latchup (SEL) in CMOS devices. We accomplish SEL tests for CPU and SRAM devices through the simulation by a pulse laser. The laser simulation results give the energy threshold for samples to undergo SEL. SEL current pulses are measured for CMOS devices in the latchup state, the sensitive areas in the devices are acquired, the major traits, causing large scale circuits to undergo SEL, are summarized, and the test equivalence between a pulse laser and ions is also analyzed.     

Stabilization of the Single-Chain Fragment Variable by an Interdomain Disulfide Bond and Its Effect on Antibody Affinity

The interdomain instability of single-chain fragment variable (scFv) might result in intermolecular aggregation and loss of function. In the present study, we stabilized H4—an anti-aflatoxin B₁ (AFB₁) scFv—with an interdomain disulfide bond and studied the effect of the disulfide bond on antibody affinity. With homology modeling and molecular docking, we designed a scFv containing an interdomain disulfide bond between the residues H44 and L100. The stability of scFv (H4) increased from a GdnHCl₅₀ of 2.4 M to 4.2 M after addition of the H44-L100 disulfide bond. Size exclusion chromatography revealed that the scFv (H44-L100) mutant existed primarily as a monomer, and no aggregates were detected. An affinity assay indicated that scFv (H4) and the scFv (H44-L100) mutant had similar IC₅₀ values and affinity to AFB₁. Our results indicate that interdomain disulfide bonds could stabilize scFv without affecting affinity.     

深入学习实践科学发展观 努力开创农村水电工作新局面

目前,全国水利系统正在贯彻落实党的十七大和十七届三中全会精神,深入开展学习实践科学发展观活动,按照中央扩大内需促进经济增长的要求,全力推进水利基础设施建设.召开全国农村水电工作座谈会,主要任务是按照科学发展观的要求,认真落实部党组的工作部署,总结2008年工作,理清农村水电发展思路,明确任务和措施,做好2009年的工作.