从环丝氨酸抗性突变株中筛选α－淀粉酶高产菌株

以枯草杆菌ＢＦ－７６５８发出了菌株，采用化学诱变剂甲基磺酸乙酯（ＥＭＳ）诱变，筛选Ｄ－环丝氨酸抗性株，逐步增加环丝氨酸浓度，从中得到α－淀粉酶高产菌株ＮＨ－５。采用往复式摇床和２Ｌ玻璃发酵罐进行发酵试验，ＮＨ－５菌株酶活较出发菌分别提高３０％和４８％。     

利用假单胞菌天冬氨酸－β－脱羧酶高效生产L－丙氨酸

通过诱变筛选得到一株具有高活性Ｌ－Ａｓｐ－β－脱羧酶的菌株ＰｓｅｕｄｏｍｏｎａｓＮＸ－１，对该株酶形成和酶反应的条件进行了详细研究，该株可以高效地转化Ｌ－Ａｓｐ生成Ｌ－ＡＩａ，转化４～５山每Ｌ培养液可转化Ｌ－Ａｓｐ量高达１４００ｇ左右，生成Ｌ－Ａｌａ浓度高达９０％以上，摩尔转化率近１００％。     

Cu－Zn－Al－Mn－Ni－Ti合金的显微组织及力学行为

本文利用电子拉伸试验、扫描电镜、金相显微镜研究了Ｃｕ－Ｚｎ－Ａｌ－Ｍｎ－Ｎｉ－Ｔｉ合金的细化效果、断裂方式、记忆性能及伪弹性。结果表明：试验合金的铸态、轧态和淬火态组织得到明显细化。晶粒细化后合金室温拉伸断裂强度为７５０ＭＰａ，断裂应变为６．６％，同未细化的Ｃｕ基记忆合金相比强度大大提高，塑性也有所改善。低温拉伸时呈穿晶断裂，断口主要为准解理台阶；高温拉伸时呈微孔聚集型断裂。试验合金的室温完全可恢复应变为４．０％，完全伪弹性恢复应变为４．５％，均达到了多晶体材料的理论平均值。     

心肌组织特异性表达质粒的构建及表达

应用ＰＣＲ方法从大鼠基因组ＤＮＡ中扩增出心肌组织特异性顺式作用元件－－心肌肌钙蛋白Ｃ（Ｃａｒｄｉａｃ Ｔｒｏｐｏｎｉｎ Ｃ，ｃＴｎＣ）增强子／启动子序列，构建成ｃＴｎＣ启动子驱动ＬａｃＺ基因的真核表达质粒ｐｃＴｎＣβ。Ｉｎ Ｖｉｔｒｏ和Ｉｎ Ｖｉｖｏ试验证明该调控元件能驱动外源性基因在心肌细胞中特异性表达。     

2－重氮－1－萘醌－5－磺酸测定方法的研究

报告了紫外分光光度法测定２－重氮－１－萘醌－５－磺酸含量的方法。水溶液中，波长为４０７ｎｍ时，２～４０μｇ／ｍｌ２－重氮－１－萘醌－５－磺酸与吸光度成直线关系。相关系数为０．９９９９８，平均回收率为１０１．３７％，相对标准偏差为０．７４５％。     

2－重氮－1－萘醌－5－磺酰氯测定方法的研究

报告了紫外分光光度法测定２－重氮－１－萘醌－５－磺酰氯含量的方法。无水乙醇溶液中，波长为３７２．５ｎｍ时，该物质在５～４０μｇ／ｍｌ内与吸光度成直线关系，相关系数为０．９９９９。平均回收率为１００．２９％，相对标准偏差为０．４２％。     

新型低温高性能G－M制冷机

介绍了美国Ｂｕｔｔｅｒｗｏｒｔｈ－Ｈｅｉｎｅｍａｎｎ低温公司用普通材料和常规技术制作的高性能Ｇ－Ｍ制冷机，描述了该制冷机的设计原理和性能。该制冷机的制冷温度已达到６．５Ｋ以下，１０Ｋ时制冷能力为５Ｗ。     

2－甲硫基－5－甲氧基－苯并噻唑合成方法的研究

以间氨基苯酚为原料，合成２－甲硫基－５－甲氧基－苯并噻唑，原料易得，合成路线短。该化合物用作感蓝染料的中间体。     

一种新型诱变技术在Vc前体(2-KLG)产生菌遗传改良中的作用

研究了低能离子注入2－酮基－L－古龙酸（2－KLG）生产菌的生物学效应。结果表明能获得较高的突变率和较广的突变谱。比较了三种离子注入2－KLG生产菌的差异，确定了最佳诱变剂量和最适注入离子。由此筛选出若干高产突变株，其糖酸克分子转化率高达97％，目前已通过工业化生产实验，取得了显著的经济效益。同时也为工业微生物的遗传改良提供了一条全新的途径。     

RS高强Al－Zn－Mg－Cu系合金热处理温度与性能的关系

本文系统研究了ＲＳ高强Ａｌ－Ｚｎ－Ｍｇ－Ｃｕ系合金淬火温度、时效温度与性能关系，同时还分析了合金的微观组织。试验得出在４７０℃淬火峰时效（Ｔ６）的拉伸性能达到σ_ｂ＝７４０ＭＰａ，σ_（０．２）＝７０２ＭＰａ，δ_５＝１０％；双级时（Ｔ７３）可获得σ_ｂ＝６３３ＭＰａ，σ_（０．２）＝６０６ＭＰａ，δ_５＝１１．５％。合金的弥散强化相是Ｃｏ_２Ｎ_９、Ａｌ_３Ｚｒ，沉淀强化相为ＧＰ区、η＇和η。     

Cell-based quantification of homocysteine utilizing bioluminescent Escherichia coli auxotrophs

A cell-based quantitative assay system for Hcy has been developed by utilizing two Escherichia coli auxotrophs that grow in the presence of methionine (Met) and either homocysteine (Hcy) or Met, respectively. A bioluminescent reporter gene, which produces luminescence as cells grow, was inserted into the auxotrophs, so that cell growth can be readily determined. When the relative luminescence unit (RLU) values from the two auxotrophs immobilized within agarose gels arrayed on a well plate were measured, the amount of Hcy was quantitatively determined on the basis of differences between two RLU values corresponding to cell growth of two auxotrophs with excellent levels of precision and reproducibility. Finally, the diagnostic utility of this assay system was verified by its employment in reliably determining different stages of hyperhomocysteinemia in human plasma samples providing CVs of within and between assays that are less than 2.9% and 7.1%, respectively, and recovery rates of within and between assays that are in the range of 99.1-103.5% and 97.5-105.5%, respectively. In contrast to existing conventional methods, the new system developed in this effort is simple, rapid, and cost-effective. As a result, it has great potential to serve as a viable alternative for Hcy quantification in the diagnosis of hyperhomocysteinemia.     

Metal biosorption capability of Cupriavidus taiwanensis and its effects on heavy metal removal by nodulated Mimosa pudica

A novel metal biosorption system consisting of the symbiotic combination of an indigenous metal-resistant rhizobial strain, Cupriavidus taiwanensis TJ208, and its host plant Mimosa pudica has been developed for the removal of heavy-metal pollutants. Free-living C. taiwanensis TJ208 cells were able to adsorb 50.1, 19.0, and 19.6 mg/g of Pb, Cu, and Cd, respectively. After nodulation via inoculation with strain TJ208, the metal uptake ability of M. pudica markedly increased, as the nodulated M. pudica displayed a high metal uptake capacity (qmax) of 485, 25, and 43 mg/g, respectively, which is 86, 12, and 70% higher than that of nodule-free plants. Moreover, with TJ208 nodules, the M. pudica plant also displayed a 71, 81, and 33% enhancement in metal adsorption efficiency (eta) for Pb, Cu, and Cd, respectively. The nodulation appeared to give the greatest enhancing effect on the uptake of Pb, which is consistent with the preference of metal adsorption ability of TJ208. This seems to indicate the crucial role that the rhizobial strain may play in stimulating metal uptake of the nodulated plant. Furthermore, the results show that metal accumulation in the nodulated plant mainly occurred in the roots, accounting for 65-95% of total metal uptake. In contrast, the nodules and the shoots only contributed to 3-12 and 2-23% of total metal uptake, respectively. Nevertheless, the specific adsorption capacity of nodules is comparable to that of the roots. Hence, this work demonstrates the feasibility and effectiveness of using the nodulated plants to promote phyto-removal of heavy metals from the polluted environment as well as to restrict the metal contaminants in the unharmful region of the plant.     

Voltammetric determination of tryptophan at a single-wall carbon nanotubes modified electrode

A single-wall carbon nanotubes (SWNT)-film coated glassy carbon electrode (GCE) was described for the determination of tryptophan. In pH 2.5 Na2HPO4-citric acid buffer, tryptophan yields a well-defined and very sensitive oxidation peak at about 1.08 V at the SWNT-film coated GCE. The oxidation peak current increases greatly and the peak potential shifts toward more negative direction at the SWNT-modified GCE in contrast to that at the bare GCE. Under optimized conditions, the oxidation peak current is proportional to the concentration of tryptophan over the range from 4 x 10(-8) to 1 x 10(-5) mol/L. The detection limit is 1 x 10(-8) mol/L at 3 min of accumulation. Using the proposed method, tryptophan in the human's blood serum samples was determined.     

Fast-gated intensified charge-coupled device camera to record time-resolved fluorescence spectra of tryptophan

The possibilities of a 200 ps gated intensified charge-coupled device (CCD) camera to record time-resolved fluorescence were explored using the fluorescing amino acid tryptophan and its derivative Nacetyl-tryptophan amide (NATA) as model compounds. The results were compared to complementary data from time-correlated single-photon counting (TCSPC) experiments. If a spectral resolution of 1-2 nm is desired, the fast-gated intensified CCD (ICCD) camera is the method of choice. For a 10(-5) M tryptophan solution, time-resolved emission spectra and intensity decays (measured over 12 ns at 25 ps resolution) could be obtained in typically 10 minutes, giving the well-known lifetimes of 0.5 and 3 ns. In addition, a longer lifetime of 7 ns was found at the red edge of the spectrum. The very short gate time of the ICCD camera allowed us to observe a shift in the emission maximum of tryptophan even within the first nanosecond of decay of the fluorescence emission. As expected from the tryptophan rotamer model, such a shift is not observed in NATA. Using amplitudes obtained by global analysis, decay-associated spectra of these lifetimes were constructed.     

共晶碳化物团球化对铸铁激光熔敷层抗裂性的影响

为提高铸铁表面大面积激光熔敷层抗裂性问题，通过冶金因元素控制熔敷层组织形态在熔敷材料中加入碱金属元素钾，研究了在激光快速加热条件下钾对铸铁激光熔敷层组织团球化的影响，进而分析了该球状组织对熔敷层抗裂性的影响，结果表明随熔敷金属内钾含量增多熔敷层内共晶碳化物组织呈球状及孤岛状，这种组织明显提高了熔敷层抗裂性，此外大量的渗碳体组织确保了熔敷层具有较高的耐磨性；获得了无裂纹的大面积搭接熔敷层，其对应合金系统为Fe-C-Si-Ni-K。     

Quantitative analysis of individual neurons by open tubular liquid chromatography with voltammetric detection

The ability to analyze individual cells is often important in biology because of the heterogeneity of tissue; this is especially true in the area of neurobiology. A method is described for the determination of trace levels of organic compounds in individual cells by open tubular liquid chromatography with voltammetric detection. In the method, a cell is isolated, an internal standard is added, the cell is homogenized and centrifuged, and the supernatant is injected directly onto the chromatography column. Since data are collected in both the electrochemical and chromatographic domains, the resolution of the method is better than that obtained by using amperometric detection. The combination of voltammetry and chromatography also aids in the identification of compounds. By use of this method three different neurons, D2, E4, and F1, from the land snail Helix aspersa are analyzed. The data show that the cells give certain unique and repeatable chemical profiles. Dopamine, serotonin, tyrosine, and tryptophan were identified and quantified in two of the cells at the femtomole level. In the third cell, only the two amino acids were observed and measured. The quantitative data indicate that the method is at least as reliable as other methods that have been applied to single cells and considerably more sensitive. The combination of qualitative and quantitative information allows for the chemical mapping of cells.     

Isolation and characterization of the heavy metal resistant bacteria CCNWRS33-2 isolated from root nodule of Lespedeza cuneata in gold mine tailings in China

A total of 108 strains of bacteria were isolated from root nodules of wild legumes growing in gold mine tailings in northwest of China and were tested for heavy metal resistance. The results showed that the bacterial strain CCNWRS33-2 isolated from Lespedeza cuneata was highly resistant to copper, cadmium, lead and zinc. The strain had a relatively high mean specific growth rate under each heavy metal stress test and exhibited a high degree of bioaccumulation ability. The partial sequence of the copper resistance gene copA was amplified from the strain and a sequence comparison with our Cu-resistant PCR fragment showed a high homology with Cu-resistant genes from other bacteria. Phylogenetic analysis based on the 16S rRNA gene sequence showed that CCNWRS33-2 belongs to the Rhizobium-Agrobacterium branch and it had 98.9% similarity to Agrobactrium tumefaciens LMG196.     

色氨酸在自制牛血清白蛋白手性柱上的拆分

利用三氯聚氰活化的氨丙基硅胶与牛血清白蛋白反应,快速而经济地制得牛血清白蛋白手性固定相。在反相模式下,将该手性固定相用于色氨酸的拆分,系统探讨了流动相pH值、柱温、有机修饰剂的种类及含量等对手性拆分的影响。色氨酸在自制牛血清白蛋白手性柱上得到了理想的拆分,分离因子可达4.33。     

Fibrous wound repair associated with biodegradable poly-L/D-lactide copolymer implants: study of the expression of tenascin and cellular fibronectin

Extracellular matrix (ECM) proteins are known to play a role in inflammatory and hyperplastic processes. Our aim in the present study was to study the distribution of tenascin (Tn), cellular fibronectins (cFn) and myofibroblasts around biodegradable poly-L/D-lactide (PLA) implants with monoclonal antibodies (MAb). Ethylene-oxide and gamma-irradiation sterilized PLA plate-type implants were inserted into the dorsal subcutaneous tissue of ten adult rabbits. Follow-up times were 4, 12, 16, 36 and 48 wk. Only some inflammatory cells were observed. In electron microscopy, a close coherence between the implant and the stromal tissue was seen. Immunoreactivity for Tn, cFn and -actin was detected as a distinct layer bordering the implant, regardless of the sterilization method for the first 36 wk. From week 36 onwards, Tn immunoreactivity was downregulated while cFn immunoreactivity still persisted. A moderate upregulation for myofibroblasts was seen on the week 48 specimens, when hydrolysation of PLA implant had started. The persistent content of myofibroblasts, Tn and cFn suggests a prolonged wound healing produced by PLA implants. The absence of Tn at the week 48 specimens suggests that cFn, rather than Tn may be needed for -actin-mediated contraction by myofibroblasts.     

快速水解法测定羽毛及其降解物中的色氨酸

通过提高水解温度,减少水解时间的前处理方法,用氨基酸自动分析仪测定羽毛及其降解物中色氨酸的测定值。分析结果表明,采用4mol/LLiOH、145℃、水解5h的快速水解法与常规前处理方法所测得色氨酸含量基本一致,方法回收率91%,变异系数2.24%。可缩短分析时间,且不影响分析结果的准确度。