固定化酶微观活性定位的X射线微区分析

利用X射线微区分析,对共价法得到的固定化L—天门冬酰胺酶的活性进行了分析。L—天门冬酰胺作为底物,MgCl2作为捕捉剂,底物经L-天门冬酰胺酶催化分解产生氨,后者和捕捉剂反应产生沉淀,可以确定固定化L-天门冬酰胺酶的催化活性部位。结果表明：大孔树脂载体,酶活较高,活性L-天门冬酰胺酶分布较均匀。并得到了固定化L-天门冬酰胺酶的活性定位的最佳条件。并对不同结构载体固定化酶活性进行了研究。     

固定化木瓜蛋白酶活性的X-射线微区分析

利用X-射线微区分析,对共价法得到的固定化木瓜蛋白酶的活性进行了分析;Na-苯甲酰-L-精氨酰胺盐酸盐作为底物,FeCl_3作为捕捉剂,底物经木瓜蛋白酶催化分解产生L-精氨酸及氨,后者和捕捉剂反应产生沉淀,可以确定固定化木瓜蛋白酶的催化活性部位。结果表明:以大孔结构吸附树脂为固定化酶载体,酶活较高,木瓜蛋白酶分布较均匀。并得到了固定化木瓜蛋白酶的活性定位的最佳条件。并对不同结构载体固定化木瓜蛋白酶的活性进行了研究。     

酶电极上葡萄糖氧化酶的活性的X射线微区分析

利用X射线微区分析, 对二氧化硅溶胶-凝胶包埋于普鲁士蓝修饰玻碳电极上的葡萄糖氧化酶的活性进行了分析; 以Ce(NO₃)₃为捕捉剂, 底物葡萄糖经葡萄糖氧化酶作用产生过氧化氢,后者与捕捉剂反应生成沉淀于酶的活性部位。从X射线微区分析结果表明： 酶电极表面固定化酶的分布均匀,且保存较高的酶活,从微观的角度说明了酶电极的性能与酶电极表面酶活分布的关系。此法制备的葡萄糖氧化酶电极具有较高的灵敏度,稳定性,这与电化学测试结果是一致的。     

微孔板荧光法对土壤糖酶活性的测定研究

应用荧光共轭物质作为底物,将96微孔板和荧光检测法结合进行稻-麦轮作系统CO₂倍增条件(FACE)下土壤两种糖酶(木聚糖酶和纤维素酶)活性的测定,探讨了微孔板结合荧光法测定糖酶活性的可行性。结果表明,此种方法可以灵敏的检测到土壤稀释液中的糖酶活性,测定结果重现性较好(变异系数最大为4.879%)。与传统的分光光度法相比,是一种准确、快速、简便的土壤糖酶活性测定方法。CO₂倍增条件下土壤木聚糖酶活性高于自然条件,且在小麦的拔节期,抽穗期和成熟期及水稻的抽穗期和成熟期显著高于对照(P<0.05),CO₂浓度升高提高作物的生长代谢水平,进而影响微生物活性造成土壤木聚糖酶活性提高。纤维素酶活性在CO₂倍增条件下未发生显著变化,说明土壤纤维素酶在短时期内对CO₂增加的响应不显著。     

微波消解-石墨炉原子吸收法测定壳聚糖中的痕量镉

采用石墨炉原子吸收法直接测定了壳聚糖中的痕量镉。试验发现,在HNO₃-H₂SO₄-HClO₄体系、HNO₃-H₂O₂体系、HCl-HNO₃体系、HF-HClO₄体系中,以HF-HClO₄ 体系消化效果最佳,经试验,0.2 g样品用1 mL HF,2 mL HClO₄消溶效果较好。以HF-HClO₄体系为消化试样、微波消解,用Pd(NO₃)₂作基体改进剂,灰化温度1 000 ℃,原子化温度2 200 ℃。该方法相对标准偏差为2.8%,回收率在97.0%～106.3%之间,该方法快速、简便、准确。     

胺基化合物修饰戊二醛交联壳聚糖树脂的合成及其红外光谱研究

研究了以三聚氯氰为活化剂,正丁胺、二甲胺、三甲胺、三乙胺、苯甲胺、对甲基苯胺、对氨基苯磺酸修饰戊二醛交联壳聚糖的制备及其红外光谱。壳聚糖1 155 cm-1的糖苷键ν_(C—O—C)吸收峰、899 cm-1的环振动吸收峰和1 030 cm-1的伯羟基ν_(C—OH)吸收峰基本不变。在3 430～3 440 cm-1的ν_(O—H)和ν_(N—H)吸收峰稍有变化,1 400～1 384 cm-1的δ_(C—H)吸收峰变化较明显。氨基化修饰交联壳聚糖仲羟基的ν_(C—OH)吸收峰由1 095 cm-1移至1 060～1 070 cm-1。三聚氯氰活化交联壳聚糖在803～812 cm-1和1 584～1 590 cm-1出现均三嗪环骨架振动吸收峰。随取代度和脱乙酰度不同,壳聚糖的酰胺Ⅰ,Ⅱ,Ⅲ峰强度变化明显。伯仲胺修饰交联壳聚糖在1 517～1 530 cm-1出现质子化氨基δ_(N—H)吸收峰,三甲胺、三乙胺修饰交联壳聚糖此峰消失或减弱,但在1 400～1 500 cm-1出现一组ν_(C—N)吸收峰。     

基于红外光谱分析研究矿化剂对铝酸钙粉制备的影响

研究了矿化剂对中低品位铝矾土对所制备铝酸钙粉的结构及其光谱性能的影响。以中低品位铝钒土和碳酸钙为主要原料,矿化剂CaF₂为添加剂,三者经充分混合、 高温煅烧和粉磨后,生产出的铝酸钙粉可直接用于制备聚合氯化铝、 聚合硫酸铝、 铝酸钠等水处理剂。通过调整原料中铝矾土和碳酸钙的质量比和矿化剂CaF₂投加量的方法优化铝酸钙粉的制备工艺,采用红外光谱分析对铝酸钙粉和铝矾土进行表征,并对矿化剂的矿化机理进行研究。红外光谱分析结果表明：加入矿化剂CaF₂,可促进铝矾土中硬水铝石、 三水铝石和高岭石的分解转化,使碳酸钙的分解完全,使原料中的铝矾土与碳酸钙进行更加充分的反应,不仅有助于碳酸钙中的Ca与铝矾土中的Si结合,还有助于促进铝矾土中的Si—O,Si—O—Al及Al—Si键的断裂,使铝矾土中的Al充分溶出,从而提高Al₂O₃的溶出率;矿化剂CaF₂的投加量(质量比)为3%时,可有效促进Al₂O₃的溶出;矿化剂CaF₂的投加量为1.5%时,不足以起到充分的矿化作用;中低品位铝矾土较高品位铝矾土更易于烧结制备铝酸钙粉;在1 250 ℃下制备铝酸钙粉的最佳物料配比是：原料中铝矾土与碳酸钙的质量比为1∶0.6,矿化剂CaF₂的投加量为3%。     

LiMBO3 : Dy3+材料的发光特性

采用固相法制备了LiM(M=Ca, Sr, Ba)BO₃ : Dy³⁺材料,并研究了材料的发光特性。LiM(M=Ca, Sr, Ba)BO₃ : Dy³⁺材料的发射光谱均呈多峰发射,对应于Ca,Sr,Ba,其主发射峰分别是Dy³⁺的⁴F_9/2→⁶H_15/2(484,486,486 nm),⁶H_13/2(577,578,578 nm)和⁶H_11/2(668,668,666 nm)跃迁。监测黄色发射峰时,所得激发光 谱峰值位置相同,主激发峰分别为331,368, 397,433,462,478 nm,对应Dy³⁺的⁶H_15/2→ ⁴D_7/2,⁶P_7/2,⁶M_21/2,⁴G_11/2,⁴I_15/2和⁶F_9/2跃迁。研究了敏化剂Ce³⁺及电荷补偿剂Li⁺、Na⁺和K⁺对LiM(M=Ca, Sr, Ba)BO₃ : Dy³⁺材料发光强度的影响。结果显示:加入敏化剂Ce³⁺提高了材料的发光强度,发光强度最大处对应的Ce³⁺浓度为3%;加入电荷补偿剂Li⁺、Na⁺和K⁺后,材料的发光强度也得到了明显提高,但发光强度最大处对应的Li⁺、Na⁺和K⁺浓度不同,依次为4%、4%和3%。     

同位素质谱法对土壤反硝化酶活性的测定研究

在评价硝化抑制剂的作用效果时, 需要确认此硝化抑制剂对反硝化过程有无影响。而对此过程的确认是通过反硝化酶活性(denitrifying enzyme activity, 简写为DEA)的测定来实现的。采用加入同位素标记底物结合同位素质谱仪来测定新型硝化抑制剂3,4-二甲基吡唑磷酸盐作用下的反硝化酶活性。结果表明, 此新型方法能够较准确的测定培养体系中的N₂O的浓度,与气相色谱法的测定结果具有良好的相关性(MS_N2O=-0.45+1.03GC_N2O,R2=0.995)。通过测定15N₂O和15N₂的丰度能够较好的区分2种反硝化酶活性(硝酸还原酶和N₂O还原酶), 且克服了传统测定中需要加入乙炔作为酶抑制剂的弊端。对DMPP作用下土壤反硝化酶的测定表明,DMPP对反硝化酶无显著影响, 说明DMPP在使用中不会影响土壤中的反硝化过程。     

26 ℃和常压至1.5 GPa压力下2-甲基戊烷拉曼光谱研究

利用碳化硅压腔在常压至1.5 GPa和26 ℃条件下对液态2-甲基戊烷进行了拉曼光谱测量,讨论了C—H拉曼峰频率、强度、面积、以及谱峰宽度随压力升高的变化规律。实验结果表明,2-甲基戊烷的拉曼位移在2 800～30 00 cm-1范围内的CH₃和CH₂的伸缩振动谱峰随着压力的增大均连续向高波数位移,其拉曼位移与压力的关系可以表示为ν_as(CH₃)=0.013 1p+2 960.1,ν_s(CH₃)=0.008 8p+2 871.0,ν_as(CH₂)=0.008 9p+2 930.2,ν_as(CH₂)’=0.007 0p+2 903.1和ν_s(CH₂)=0.007 9p+2 844.7。另外处理实验结果时发现,在0～1.5 GPa条件下,2-甲基戊烷的ν_as(CH₃)拉曼位移可以进行压力标定,其方程为：P(MPa)=76.2(Δν_p)_{2 960}+21.65(r2=0.995 8)。该压力体标定剂,适合于不希望有Si和Al等元素出现的体系。     

Effects of ultrasound on the catalytic activity of matrix-bound glucoamylase

The effect of ultrasonic waves on the activity of glucoamylase bound to a porous polystyrene matrix is investigated in this Paper. The immobilized enzyme was sonated in a flow cuvette at frequencies between 1 and 11 MHz and sound intensities up to 5 kW m-2. The effect was measured as a function of the type and concentration of the substrate, carrier particle size, flow rate of the substrate solution and ultrasonic frequency. The activity increase is discussed in terms of a possible ultrasonic mechanism.     

Biological functionality of active enzyme structures immobilized on various solid surfaces

We have investigated biological functionality of immobilized enzyme structures according to the immobilizing routes and the surface properties. Horse radish peroxidase (HRP) was immobilized on various solid surfaces such as gold, SiO₂, sapphire and anodized aluminum oxide (AAO) membrane via non-specific adsorption, avidin-mediated and biotin/avidin-mediated layer-by-layer (LBL) assembly. The catalytic activity as a measure of biological functionality, of the biotin-HRP immobilized by avidin-mediated LBL assembly was found to be better than that of the directly adsorbed HRP on the surfaces of gold, SiO₂, sapphire and AAO due to the easy accessibility of reactants to active sites as well as the retention of three dimensional native structure of enzyme for bioactive functionality. In addition, the catalytic activity of the biotin-HRP in LBL-assembled avidin/biotin-HRP on AAO membrane was found to be highly better than that on other substrates due to the increasing amount of immobilized HRP which can be attributed to the high surface area of the substrate. SEM images show that the functional avidin/biotin-HRP enzyme structures were successfully realized by a sequential process of non-specific adsorption and LBL assembly via biotin–avidin interaction.     

Surface functionalization of chitosan-coated magnetic nanoparticles for covalent immobilization of yeast alcohol dehydrogenase from Saccharomyces cerevisiae

A novel and efficient immobilization of yeast alcohol dehydrogenase (YADH, EC1.1.1.1) from Saccharomyces cerevisiae has been developed by using the surface functionalization of chitosan-coated magnetic nanoparticles (Fe₃O₄/KCTS) as support. The magnetic Fe₃O₄/KCTS nanoparticles were prepared by binding chitosan alpha-ketoglutaric acid (KCTS) onto the surface of magnetic Fe₃O₄ nanoparticles. Later, covalent immobilization of YADH was attempted onto the Fe₃O₄/KCTS nanoparticles. The effect of various preparation conditions on the immobilized YADH process such as immobilization time, enzyme concentration and pH was investigated. The influence of pH and temperature on the activity of the free and immobilized YADH using phenylglyoxylic acid as substrate has also been studied. The optimum reaction temperature and pH value for the enzymatic conversion catalyzed by the immobilized YADH were 30 °C and 7.4, respectively. Compared to the free enzyme, the immobilized YADH retained 65% of its original activity and exhibited significant thermal stability and good durability.     

Immobilized protease on the magnetic nanoparticles used for the hydrolysis of rapeseed meals

(3-aminopropl) triethoxysilaneand modified magnetic nanoparticles with the average diameter of 25.4 nm were synthesized in water-phase co-precipitation method. And then these nanoparticles were covalently coupled with alkaline protease as enzyme carrier by using 1,4-phenylene diisothlocyanate as coupling agent. Experiments showed that the immobilized protease can keep the catalytic bioactivity, which can reach to 47.8% when casein was served as substrate. Results showed that the catalytic activity of immobilized protease on these magnetic nanoparticles could retain 98.63±2.37% after 60 days. And it is more stable than the free protease during the shelf-life test. The enzyme reaction conditions such as optimum reaction temperature and pH are the same as free protease. Furthermore, mix-and-separate experiments showed that the immobilized protease could be recycled through the magnetic nanoparticles after the biocatalysis process. When the rapeseed meals were used as substrate, the degree of hydrolysis of immobilized alkaline protease achieved 9.86%, while it was 10.41% for the free protease. The macromolecular proteins of rapeseed meals were hydrolyzed by immobilized protease into small molecules such as polypeptides or amino acids. Thus, a novel efficient and economic way for the recycling of enzymes in the application of continuous production of active peptides was provided based on these magnetic nanoparticles.     

60 MeV/u 18O离子同天然铀反应钡同位素截面的测定

通过60MeV/u18O离子照射天然铀靶产生Ba放射性同位素,使用BaCl2沉淀法从大量铀和其它反应产物混合物中分离出Ba.通过离线γ谱学方法测量了Ba样品的γ射线单谱,根据Ba同位素特征γ射线峰的强度及其它相关数据计算了Ba同位素的生成截面.发现在厚铀靶的情况下,缺中子Ba同位素仍有较高的截面. The radioactive Ba isotopes were produced by 60 MeV/u~(18)O ion bombardment of natural uranium. Ba was separated from U and the reaction product mixture by BaCl_(2) precipitation. The Ba fraction was measured by off-line γ-ray spectroscopy. The cross sections of the individual Ba isotope were calculation based on the intensities of the character γ-ray peaks of Ba isotopes and other relative information. It was found that the n-deficient Ba isotopes have higher cross sections using the thick uranium targets.     

Immobilization of protein molecules on step-controlled sapphire surfaces

We have studied effects of surface morphology on immobilization of protein molecules using step-controlled sapphire surfaces. Preferential adsorption of avidin molecules on the step edges was observed on the single-stepped sapphire surface. A randomly-stepped sapphire surface was found to be suitable for high-density immobilization of protein molecules. These results indicate atomic scale structures of the substrate surface influence the adsorption efficiency of the proteins. By using an atomic force microscopy (AFM) equipped with a biotin-modified cantilever, we have confirmed that the immobilized avidin molecules on the substrates keep their biological activity. This means that the ligand-receptor interaction can be detected using the phase image mode of a standard AFM.     

Luminescence of Ba0.85MgAl10O16.94：Eu^2＋0.09 with different fluxes

BaMgAl10O17:Eu^2 , known as BAM, is a very important blue-emitting phosphor used in plasma display panels (PDP) and three band fluorescent lamps. In this paper, the Ba0.s5MgAl10O16.94:Eu^2 0.09 phosphors with different fluxes (BaF2, MgF2, AIF3, BaCl2, MgCl2, AICl3, H3BO3) were prepared by high temperature solid-state reaction method and the influence of different fluxes on the luminescence of Ba0.85MgAl10O16.94:Eu^2 0.09 phosphor was studied under 254nm excitation and vacuum ultraviolet (VUV) excitation. It was found that fluorides have better flux effects than chlorides and H3BO3. The mechanism of particle growth in the presence of flux in the process of phosphor preparation is discussed in detail. Particle size distribution and the crystal structure of the phosphors are also analysed.