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。     

磁场耦合电化学合成聚合氯化铝的性能

以金属铝板为阳极,金属铁板为阴极,0.1 mol/L的AlCl3水溶液作电解液,应用与重力方向平行的外加磁场耦合直流电解法合成聚合氯化铝(PAC).在磁通密度0.4 T,相邻电极间距15 mm,电解槽电压2.4V,电流密度300 A/m2下,成功制备出盐基度Ba=2.4,总铝含量(AlT)为0.6 mol/L,有效絮凝成分Al13占AlT83.2%的PAC产品,其电压效率85.2%,电能效率81.5%,比电极面积为140.1 m2/m3.恒流法测试表明,磁场对电极极化有抑制作用,并可增大电极表面膜溶解速率,且随磁通密度增加而增强.     

高效液相色谱-蒸发光散射检测法测定藜芦中的介藜芦碱和藜芦胺

建立了高效液相色谱-蒸发光散射检测(HPLC-ELSD)测定藜芦中介藜芦碱、藜芦胺含量的方法,并对4种藜芦属药材样品进行了测定。采用的色谱柱为Kromasil C18柱(250 mm×4.6 mm, 5 μm),以乙腈和0.1%三氟乙酸水溶液为流动相进行梯度洗脱,洗脱程序为:0～5 min, 20%乙腈; 5～30 min, 20%乙腈～40%乙腈, 30～40 min, 40%乙腈～20%乙腈; 40～45 min, 20%乙腈;流速为0.8 mL/min;柱温为35 ℃;采用ELSD检测,漂移管温度为98 ℃,载气流速2.2 L/min 。介藜芦碱和藜芦胺的线性范围分别为42.05～980 mg/L和43.77～1020 mg/L;平均回收率分别为99.2%和101.4%,相对标准偏差分别为1.7%和2.1% (n=6);信噪比为3时,测得介藜芦碱和藜芦胺最低检测限分别为18.37 mg/kg和21.50 mg/kg。该方法快速简便、灵敏度和分离度好,适用于藜芦药材中活性生物碱的测定。     

Ni修饰碳纳米管促进合成气高效制甲醇Cu基催化剂研究

利用化学还原沉积法,制备一类Ni高度分散/修饰的多壁碳纳米管基新型材料y%Ni/MWCNT(y%为质量百分数),并用其作为促进剂,制备共沉淀型y%Ni/MWCNT促进的合成气高效合成甲醇Cu-ZnO-Al₂O₃催化剂,Cu₆Zn₃Al₁-x%(y%Ni/MWCNT)(x%为质量百分数).实验发现,Ni对MWCNT的预修饰能明显地提高单纯MWCNT促进的Cu-ZnO-A1₂O₃催化剂对合成气转化为甲醇的催化活性.在2.0 MPa,493 K,V(H₂):V(CO):V(CO₂):V(N₂)=62:30:5:3,GHSV=2700 mL(STP)·h^-1·(g-cat.)^-1的反应条件下,所观测CO转化率达34%,相应甲醇时空产率为442 mg·h^-1·(g-cat.)^-1,分别是非促进的基质催化剂Cu₆Zn₃Al₁[最佳操作温度513 K时为320 mg·h^-1·(g-cat.)^-1]和单纯MWCNT促进的催化剂Cu₆Zn₃Al₁-12.5%MWCNT[最佳操作温度503 K时为378 mg·h^-1·(g-cat.)^-1]的1.38和1.17倍.在反应温度≤503 K时产物中甲醇的选择性≥98%;当反应温度＞503 K时有可观量CH₄的生成,其选择性随催化剂中M含量及反应温度上升而增加.为兼获较高的CO转化率及相应甲醇选择性,催化剂的组成以Cu₆Zn₃Al₁-12.5%(8%Ni/MWCNT)为佳,反应温度以～493 K为宜.结合催化体系的表征(XRD,TPR,TPD)等结果,讨论了y%Ni/MWCNT促进剂的作用本质.     

Alkali Metal-incorporated Mesoporous Smectites:Crystallinity and Textural Properties

IntroductionSynthesized smectite- like compounds are a newkind of mesoporous materials[1] .Compared withother mesoporous materials like MCM and FSMfamilies[2 ,3 ] ,these smectite- type materials can havewide variations in both chemical composition andpore structure depending on the precursors usedand the synthesis conditions.Various di- or tri- va-lent metals such as Mg,Co,Ni,Fe,Zn and othercatalytically active elements can be introduced intosmectite- like materials.These flexible feature…     

(RXNR)_4(X=B，Al，Ga)簇合物的结构与化学键性质

用自洽场理论（HF）和密度泛函理论（DFT）的B3LYP方法,在6-311G~*水平上 ,首次从理论上研究了(RXNR)_4 (R = B,Al,Ga;R = H,CH_3,NH_2,OH)簇合 物及其先驱化合物（RXNR）_2的几何构型、电子结构和化学键性质,并与其异构体 及其等电子化合物进行了比较。结果表明,(RBNR)_4为环状骨架结构,(RAlNR)_4 和(RGaNR)_4为建立骨架结构。     

(XNR)_4立方簇合物结构与稳定性的DFT研究

用密度泛函理论(DFT),在B3LYP/CEP-121G水平上,首次对(XNR)_4 [X = C, Si,Ge,Sn,Pb;R = H,CH_3,C(CH_3)_3,Si(CH_3)_3,C_6H_5]立方簇合物的 几何构型、电子结构、振动光谱和化学键性质进行了研究,并对其分子碎片(XNR) _2进行了相同方法的优化计算。结果表明,(CNR)_4对应原5种结构均不能稳定存在 。(XNH)_4对应原5种结构稳定性较低。对于同一取代基R,簇合物的稳定性大小顺 序为：(PbNR)_4>(SnNR)_4>(GeNR)_4>(SiNR)_4>(CNR)_4。     

Anomalous Emission And Carrier Effect of Fresh Porous Silicon

IntroductionThe study of luminescent silicon material[1] ,especially porous silicon( PS) ,has received muchattention owing to its potential application ininformation technology. Many models have beenproposed to explain their photoluminescnece andelectroluminescence[1— 11] . Three of the mostpopular models are the quantum confinement[1,2 ] ,surface trapping[3 ,4] ,and oxygen related chemicalspecies formation[5,6] .It has been suggested thatsurface chemical reaction plays an importantrole info…     

Reaction of Crossed Diperoxidation Between Cyclic Ketones and Alkyl Ketones

IntroductionThe thermal and photochemical decompositionof the diperoxides of cyclic ketones has been foundto provide a general method for the facile synthesisof macrocyclic compounds[1,2 ] .In addition,the useof diperoxides as initiators in polymerization hasbeen studied[3] .Forthose reasons,a better methodfor the synthesis of the requisite diperoxides isrequired.There are two different methods for thepreparation of the diperoxides. Griesbaum[4 ]obtained cyclopentanone diperoxide(yield 1 3 % …     

Studies on Thermal Stability and Fluid Property of PVC Filled with Hydrotalcite

IntroductionIt is well known that PVC is a kind of valuableplastic and used in many fields.But PVC isunstable against heat and light,and at the heat-molding step,the thermal decomposition of it maytake place.Finally,the decomposition will reducethe mechanical strength and lose otherproperties ofPVC.In order to overcome those disadvantages,athermal stabilizer is added in the PVC material toreduce the thermal decomposition,and organiccompounds of metals such as Sn,Pb,Ca,Ba,Znand Cd are u…