产纤维素酶原生质体形成和再生条件选择

研究了4种营养缺陷型产纤维素酶菌的原生质体形成和再生条件。结果表明 ,它们原生质体形成条件均以0.2mol·L-1(pH5.8)磷酸缓冲液为好。绿色木霉(Trichodermaviride)UV2 -11 和另一未定木霉(T.sp.)UV2 -2 以0.7mol·L-1KCl的渗透稳定剂为好 ,菌丝菌龄分别为20,18～20h ;康宁木霉(T.Koningii)UV2 -1 和UV2 -15 以0.6mol·L -1NaCl的渗透稳定剂为好 ,菌丝菌龄均为16～20h,酶解时间均为2～3h。原生质体再生培养基以加入0.5%酵母膏和0.5 %泛酸钙的改良Czapek培养基效果好 ,用0.7mol·L-1 KCl和NaCl作为渗透稳定剂 ,菌株原生质体的再生率较高

氮肥和钾肥强化龙葵修复镉污染土壤

采用室外盆栽实验,研究了施用氮肥[(NH4)2SO4]和钾肥(KCl)对镉超积累植物龙葵(Solanum nigrumL.)的生长和吸收累积Cd的影响.结果表明,(NH4)2SO4虽不能显著提高龙葵地上部Cd含量,但可显著提高龙葵地上部干重,因而显著提高了龙葵地上部Cd的积累量,最大可提高2.8倍;KCl在高浓度处理时可以显著提高龙葵地上部Cd含量,然而它对地上部干重有抑制作用,最终没能提高龙葵地上部Cd的积累量.施用(NH4)2SO4可显著降低土壤pH值,但对土壤有效态Cd含量无显著影响;施用KCl可使土壤pH值显著提高,同时使土壤有效态Cd含量显著增加.(NH4)2SO4的强化龙葵修复效果较好.

缓释尿素中硝化抑制剂DMPP的气相色谱法测定

建立了一种检测缓释尿素中吡唑类硝化抑制剂DMPP的气相色谱法。DMPP在尿素水溶液中可定量转化为DMP,从5种有机溶剂中选择氯仿作为DMP的萃取剂,并采用加入KCl盐析的方法将萃取率从96.1%提高到99.5%。本文采用吡啶作为内标物,通过DB-1701气相色谱柱,氢火焰离子化检测器(FID)定量检测氯仿溶液萃取相中的DMP。萃取率为98.8%~100.4%;添加回收率为98.1%~99.5%;RSD为0.84%~1.6%。应用本法测定自制缓释尿素中DMPP质量分数为0.44%。

石灰性土壤供氮能力几种化学测定方法的评价研究

以采自于黄土高原差异较大的25个农田耕层石灰性土壤为供试土样,以淋洗和未淋洗土壤起始NO3--N小麦和玉米两季盆栽试验作物累积吸氮量为参比,对8种反映旱地土壤供氮能力的化学方法进行比较研究。结果表明,在一定程度上,可用有密切关系的土壤全氮或有机质,反映有机氮或全氮存在较大差异的土壤供氮能力,但其灵敏性较差。石灰性土壤矿质氮,特别是NO3--N与未淋洗土壤起始NO3--N作物吸氮量之间有较高相关性(r=0.884,P<0.01),而与淋洗土壤起始NO3--N作物吸氮量间相关系数仅为0.472(P<0.05),说明矿质氮可反映土壤当前供氮水平,而不能反映土壤潜在供氮能力;石灰性土壤起始NO3--N对各化学方法与作物吸氮量之间相关性影响较大。酸性高锰酸钾法既可反映土壤潜在供氮能力,也可反映土壤总供氮能力;酸性高锰酸钾法的修订方法,即硫酸—高锰酸钾法提取出的NH4+-N值接近于KCl水浴法提取出的NH4+-N值,该方法在反映土壤总供氮能力方面与酸性高锰酸钾法相当,但在反映土壤潜在供氮能力方面不及酸性高锰酸钾法优越。KCl水浴法在评价石灰性土壤供氮能力方面,与酸性高锰酸钾法的效果基本相同;沸水浸取法和NaHCO3-UV...

模拟酸雨对果园土壤主要形态酸变化的影响研究

采用室内淋溶的方法研究了模拟酸雨对果园土壤pH(H2O)、pH(KCl)、交换性酸(EA)、交换性铝(EAl)、可滴定酸度(BNC)等各形态酸的变化影响,并依据淋溶前后各形态酸的含量评价了土壤酸度的变化。试验结果表明:以土壤pH(H2O)值作为供试土壤酸化指标,pH≤4.5的模拟酸雨淋溶促进了土壤酸化,而pH≥5.5的酸雨淋溶缓冲了土壤的酸化;以土壤pH(KCl)值、交换性酸(EA)、交换性铝(EAl)或可滴定酸度(BNC)作为土壤酸化的指标,pH2.5的酸雨淋溶促进了土壤酸化,而pH≥3.5的淋溶处理缓冲了土壤的酸化,土壤酸度减弱。

C-60 trianion-mediated electrocatalysis and amperometric sensing of hydrogen peroxide

Heterogeneous electrocatalytic reduction of hydrogen peroxide (H2O2) by C-60 is reported for the first time. C-60 is embedded in tetra octyl ammonium bromide (TOAB) film and is characterized by scanning electron microscopy and cyclic voltammetry. Electrocatalytic studies show that the trianion of C-60 mediates the electrocatalytic reduction of H2O2 in aqueous solution containing 0.1 M KCl. Application of such film modified electrode as an amperometric sensor for H2O2 determination is also examined.

F-肌动蛋白与负电荷磷脂膜的相互作用研究

细胞膜的内膜含有大量的负电荷磷脂,研究F2肌动蛋白与负电荷磷脂的相互作用将有助于更深入 地了解细胞骨架与细胞膜的体内相互作用机制。在金片和金电极上分别构建了负电荷磷脂的杂化双层磷脂 膜,通过表面等离子体共振方法( SPR)和电化学阻抗技术研究了F2肌动蛋白与负电荷磷脂膜的相互作用。结 果表明, F2肌动蛋白可以在没有中间联系蛋白的情况下,直接与负电荷磷脂膜发生相互作用。钙离子可以有 效地促进它们的相互作用,表明钙离子在其中发挥了重要作用。高浓度的KCl显著抑制它们的相互作用,表 明这种相互作用主要受静电作用影响。实验结果进一步证明在F2肌动蛋白与负电荷磷脂膜相互作用时,除 了可以通过其它蛋白发生间接相互作用外,还可以与磷脂膜发生直接的相互作用。

Crystalline organic superlattice

Highly crystalline organic superlattice has great potential for providing innovative function in organic devices. With studies of the structure and fundamental electronical properties, we have demonstrated the phathalocynine organic superlattice, which is a structure composed of periodically alternating crystalline layers of H2Pc and F16CuPc. A periodical crystal structure and electronic structure appear in this organic superlattice system. High density of mobile electrons and holes distribute periodically in F16CuPc and H2Pc layers, respectively, leading to a significant change in intrinsic properties of organic semiconductors.

Electrolytic Deposition and Diffusion of Lithium onto Magnesium-9 Wt Pct Yttrium Bulk Alloy in Low-Temperature Molten Salt of Lithium Chloride and Potassium Chloride

The electrolytic deposition and diffusion of lithium onto bulk magnesium-9 wt pct yttrium alloy cathode in molten salt of 47 wt pct lithium chloride and 53 wt pct potassium chloride at 693 K were investigated. Results show that magnesium-yttrium-lithium ternary alloys are formed on the surface of the cathodes, and a penetration depth of 642 mu m is acquired after 2 hours of electrolysis at the cathodic current density of 0.06 A center dot cm(-2). The diffusion of lithium results in a great amount of precipitates in the lithium containing layer. These precipitates are the compound of Mg41Y5, which arrange along the grain boundaries and hinder the diffusion of lithium, and solid solution of yttrium in magnesium. The grain boundaries and the twins of the magnesium-9 wt pct yttrium substrate also have negative effects on the diffusion of lithium.

Prussian Blue/Multiwalled Carbon Nanotube Hybrids: Synthesis, Assembly and Electrochemical Behavior

Prussian blue/carbon nanotube (PB/CNT) hybrids with excellent dispersibility in aqueous solutions were synthesized by adding CNTs to an acidic solution of Fe3+, [Fe(CN)(6)](3-) and KCl. Fourier transform infrared spectroscopy, UV-vis absorption spectroscopy and scanning electron microscopy were employed to confirm the formation of PB/CNT hybrids. The PB nanoparticles formed on the CNT surfaces exhibit a narrow size distribution and an average size of 40 nm. The present results demonstrate that the selective reduction of Fe3+ to Fe2+ by CNTs is the key step for PB/CNT hybrid formation. The subsequent fabrication of the PB/CNT hybrid films was achieved by layer-by-layer technique. The thus-prepared PB/CNT hybrid films exhibit electrocatalytic activity towards H2O2 reduction.

Application of Ru(bpy)(3)(2+) in control and formation of gold surface nanostructure through oxidation-reduction cycling

It was studied that the nanostructure formed on a gold surface via a simple oxidation-reduction cycles (ORC) in 0.1 M KCl containing Ru(bpy)(3)(2+) with different concentrations. Atomic force microscopy (AFM) and energy-dispersed spectroscopy (EDS) were used to characterize the nanostructure formed on the gold surface. Sweep-step voltammetry and corresponding electroluminescence (ECL) response, in situ electrochemical quartz crystal microbalance (EQCM) measurement were used to monitor the ORC. procedure. It was found that the surface structure became more uniform in the presence of Ru(bpy)(3)(2+), and the surface roughness was decreasing with the increasing of Ru(bpY)(3)(2+) concentration, suggesting a simple and effective method to control the formation of nanostructure on the gold surface.

Interfacial supramolecular self-assembled monolayers of C-60 by thiolated beta-cyclodextrin on gold surfaces via monoanionic C-60

The supramolecular self-assembled monolayers (SAMs) of C-60 by thiolated beta-cyclodextrin (CD) on gold surfaces were constructed for the first time using C-60 monoanion. The results indicate that monoanionic C-60 plays a crucial role in the formation of the C-60-containing self-assembled monolayers. The generation of C-60 monoanion and the formation process of C-60 SAMs were monitored in-situ by UV-visible and near-IR spectroscopy. The resulting C-60 SAMs were fully characterized by spectroscopic ellipsometry (SE), cyclic voltammetry, X-ray photoelectron spectroscopy (XPS), and water contact angle measurements. After the immobilization of C-60 by the SAMs of thiolated beta-CD, the film thickness increased by approximately 1 nm from 0.8 to 1.8 nm as determined by SE, demonstrating the formation of the supramolecular self-assembled monolayers of thiolated beta-CD/C-60. The new C-60 SAMs exhibited one quasi-reversible redox couple at half wave potential of -0.57 V vs SCE in aqueous solution containing 0.1 M KCl. The surface coverage of C-60 on the gold surfaces was estimated to be 1.1 x 10(-10) mol cm(-2). The XPS showed the assembly of C-60 over the thiolated beta-CD SAMs.

Copper hexacyanoferrate multilayer films on glassy carbon electrode modified with 4-aminobenzoic acid in aqueous solution

4-Aminobenzoic acid (4-ABA) was covalently grafted on a glassy carbon electrode (GCE) by amine cation radical formation during the electrooxidation process in 0.1 M KCl aqueous Solution. X-ray photoelectron spectroscopy (XPS) measurement proves the presence of 4-carboxylphenylamine on the GCE. Electron transfer processes of Fe(CN)(6)(3-) in solutions of various pHs at the modified electrode are studied by both cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Changing the solution pH would result in the variation of the terminal group's charge state, based on which the surface pK(a) values were estimated. The copper hexacyanoferrate (CuHCF) multilayer films were formed on 4-ABA/GCE prepared in aqueous solution, and which exhibit good electrochemical behavior with high stability.

Facile preparation of ZnTiO3 ceramic powders in sodium/potassium chloride melts

A facile molten salt synthesis route was developed to prepare ZnTiO3 ceramic powders with simple oxides ZnO and TiO2 using sodium and potassium chloride eutectic salts as flux. The role of calcination temperature and time and the amount of salt addition to ZnTiO3 formation was investigated by thermogravimetry-differential thermal analysis, X-ray diffraction and Fourier transformation-infrared spectroscopy measurements. Pure hexagonal phase of ZnTiO3 could be obtained from the mixture of the simple oxides and the chlorides (50 mol% KCl, 20 times to oxides in molar ratio) heating at 800 degrees C for 6 h. The scanning electron microscopy images revealed the products were hexagonal sheets of about 1-3 mu m size. Increasing the amount of salt aids in reducing the crystal sizes of final ceramic powders because of diluting the solution.

Estimation thermal expansion coefficient from lattice energy for inorganic crystals

By using the study of the lattice energy and the structural parameters of binary inorganic crystals, a new parameter reflecting the thermal expansion property has been found, the relation between the linear expansion coefficient and new parameter has been established. A semiempirical method for evaluation of linear expansion coefficient from the lattice energy is presented, and developed to the complex crystals. The estimated values of the linear expansion coefficients of both simple and complex crystals are in good agreement with the experimental values.