锰氧化菌激活及生物氧化锰去除乙炔基雌二醇试验研究

利用污水厂好氧污泥进行锰氧化细菌的激活试验,探究pH值以及初始Mn2+浓度对激活效果的影响,采用高通量测序技术分析激活前后微生物群落变化,利用X射线衍射(X-ray diffraction,XRD)技术对产生的生物氧化锰进行表征,研究pH值和投加量对生物氧化锰去除乙炔基雌二醇(17α-ethinylestradiol,...     

Fermentation optimization to improve production of antagonistic metabolites by Bacillus subtilis strain BS501a

To improve antagonistic metabolites production of Bacillus subtilis strain BS501a,physical parameters of fermentation and metal inorganic salts in medium,namely initial pH value,culture temperature,fermentation time,concentrations of CaCl2,FeSO4,ZnSO4,MnSO4 and MgSO4,were optimized using one-factor-at-a-time and orthogonal tests.The results show that the optimal physical parameters of fermentation are an initial pH of 7.0,a culture temperature of 30 °C,and a fermentation time of 48 h.The optimal concentrati...     

Preparation of calcium phosphate coating on pure titanium substrate by electrodeposition method

The influences of pH value, electrolyte temperature and loading time on depositing calcium phosphate coating on pure titanium substrate by electrodeposition process were investigated. The process was carried out with an electrochemical work-station supplying a direct current power at potential of -0.8V (vs SCE). The electrolyte consists of 7 mmol·L-1 CaCl2·2H2O, 3 mmol·L-1 Ca(H2PO4)2·H2O and 2.5% H2O2. NaOH and HCl solutions were used to adjust pH value. The deposited samples were characterized by X-ray diffraction and scanning electron microscope. The comparison of the deposits obtained at lower and higher pH values demonstrates that the crystallization process at the interface is favoured by high pH value. With temperature increasing, the deposited hydroxyapatite is occasionally of plate-like shape, and the width and the length of the deposited calcium phosphates at 65 ℃ are larger than those at 55 ℃. Therefore, it is confirmed that the morphology and microstructure of electrochemically deposited calcium phosphates can be regulated. Additionally, the coating formed in electrolyte with H2O2 additive is homogeneous and the evolution of H2 bubble can be eliminated.     

Synthesis of γ-Al2O3 nanoparticles by chemical precipitation method

Highly pure active γ-Al₂O₃ nanoparticles were synthesized from aluminum nitrate and ammonium carbonate with a little surfactant by chemical precipitation method. The factors affecting the synthesis process were studied. The properties of γ-Al₂O₃ nanoparticles were characterized by DTA, XRD, BET, TEM, laser granularity analysis and impurity content analysis. The results show that the amorphous precursor Al(OH)₃ sols are produced by using 0.1 mol/L Al(NO₃)₃ · 9H₂O and 0.16 mol/L (NH₄)₂CO₃ · H₂O reaction solutions, according to the volume ratio 1.33, adding 0.024% (volume fraction) surfactant PEG600, and reacting at 40 °C, 1 000 r/min stirring rate for 15 min. Then, after stabilizing for 24 h, the precursors were extracted and filtrated by vacuum, washed thoroughly with deionized water and dehydrated ethanol, dried in vacuum at 80°C for 8 h, final calcined at 800 °C for 1 h in the air, and high purity active γ-Al₂O₃ nanoparticles can be prepared with cubic in crystal system, O _H ⁷ -FD3M in space group, about 9 nm in crystal grain size, about 20 nm in particle size and uniform size distribution, 131. 35 m²/g in BET specific surface area, 7 – 11 nm in pore diameter, and not lower than 99.93% in purity. Foundation item: Project(03JJY3015) supported by the Natural Science Foundation of Hunan Province     

Influence of rare earth co-dopant on the photocatalytic property of TiO<Subscript>2</Subscript> nano-particles

A series of nanometer TiO2 photocatalysts co-doped respectively with rare earth Er3+-Ce3+ and La3+-Fe3+ were prepared by sol-gel method,and the photocatalytic activity under ultra-violet light was evaluated by photocatalytic degradation of methyl blue.The crystallographic forms,particles size,and morphology were characterized by XRD and TEM.The results showed that the optimum heat temperature of co-doped TiO2 was 550 ℃,and the co-doped TiO2 kept anatase.The anatase crystal had the average size of 20 nm.The ...     

海参肠碱性磷酸酶的提取及粗酶的特性研究

碱性磷酸酶(Alkaline phosphatase,ALP)是最重要的磷酸酶之一,在生物体内直接参与磷酸基团的转移和代谢过程。本文研究了海参肠碱性磷酸酶粗酶的提取,并分析了其酶学特性。经含有0.2%Triton X-100的Tris-HCl缓冲液(pH 8.9)浸提、正丁醇处理、70%硫酸铵沉淀和超滤等步骤获得海参肠ALP粗酶,纯化倍数达到2.74倍,得率为63.32%。ALP粗酶的最适反应pH为11.0,在pH 10.0～12.0稳定性较好;最适反应温度为45℃,在20～45℃具有很高的稳定性。金属离子Mg2+(1～30mmol/L)、Zn2+(<10mmol/L)对海参肠ALP粗酶具有显著的激活作用;Fe3+、Fe2+、Cu2+和Mn2+(10mmol/L)可明显抑制该酶活力。EDTA-Na2、DTT、Na2WO4及Na2HPO4对海参肠ALP粗酶有明显的抑制作用,抑制程度依次为:EDTA-Na2>DTT>Na2WO4>Na2HPO4。     

Synthesis of polycrystalline Yb:Gd3Ga5O12 nanopowders by homogeneous precipitation method

The Ytterbium doped gadolinium gallium garnet [Yb³⁺:Gd₃Ga₅O₁₂, Yb:GGG] precursor powders were synthesized via homogeneous precipitation method using Yb₂O₃, Ga₂O₃, Gd₂O₃ and ammonium bicarbonate [NH₄HCO₃] as precipitator, and ammonium sulfate [(NH₄)₂SO₄] as additive. The evolution of phase composition and micro-structure of the powders were characterized by — TG DTA, XRD, IR, and TEM. The results indicate that all precursor powders completely transform to Yb:GGG phase by calcining at 900 °C for 8 h, the resultant powders are well dispersed and have smaller particle size approximately 80 nm owing to the electrostatic effect.     

Electrochemical mechanism of rusticyanin （Rus.） isolated from A. ferrooxidans measured by Rus.-ZnS-QDs/L-Cys/Au electrode

Electrochimcal behaviors of rusticyanin (Rus.) isolated from Acidithiobacillus ferrooxidans were investigated through Rus.-ZnS-QDs/L-Cys/Au electrode.The cyclic voltammetric results indicate that rusticyanin immobilized on the surface of Rus.-ZnS-QDs/L-Cys/Au electrode can undergo a direct quasi-reversible electrochemical reaction.The immobilized rusticyanin is not denatured and still retains its activity in the temperature range of 19-43 °C.The reduction ability of the protein increases and its oxidation a...     

Phase structure and electrical properties of La<Subscript>2</Subscript>O<Subscript>3</Subscript>-doped BiInO<Subscript>3</Subscript>-PbTiO<Subscript>3</Subscript> ceramics with high curie temperature

The phase structure and electrical properties of pure and La2O3-doped Bi-InO3-PbTiO3 （BI-PT） ceramics were studied respectively. In （1 -x）BI-xPT （x=0.72-0.80） ceramics, the stability of tetragonal phase increased with increasing x, and pure perovskite structure was obtained for x=-0.80 ceramics. The phase transition temperature range was between 575 ℃ and 600 ℃ for x=0.72-0.80 ceramics, higher than that of PT （-490 ℃）. The c/a ratio almost linearly decreased with increasing La2O3 content in x-0.80 ceramics. It is believed that Pb^2＋ vacancies were formed by La^3＋ substituting Pb^2＋ in La2O3-doped BI-PT ceramics. Tc shifted to lower temperature by 30 ℃/mol% La2O3. The maximum dielectric constant 8557 around 559 ℃ was exhibited in 0.5mol%-doped BI-0.80PT ceramics. La2O3-doped ceramics could be poled resulting from decreasing of c/a ratio and improving of dielectric loss and resistivity. The maximum piezoelectric coefficient d33 was 12 pC/N for 2mol%-doped BI-0.80PT ceramics.     

白头翁皂苷糖苷酶的纯化及其酶学性质

本实验对由Absidiasp.B00菌产的白头翁皂苷糖苷酶进行了分离纯化,得到了电泳纯酶蛋白,并对该酶的酶学性质进行了研究。结果表明,该酶的分子质量约为79 ku,酶反应的最适pH和温度分别为5.0和40℃,在40℃以下,pH 3.0~7.0条件下稳定性较好;金属离子Na+、K+、Mg2+、Ca2+对酶反应的影响不大,而Fe3+、Zn2+、Cu2+对其有很明显的抑制作用;酶反应动力学研究表明,vmax=0.16 mmol/(L.h),km=7.17 mmol/L。     

The Effect of Bi2O3 on the Structure and Microwave Dielectric Properties of Ba6-3xNd8＋2xTi18O54 System（x=2/3）

The structures and dielectric properties of Ba6-3xNd8＋2xTi18O54 system（x=2/3） doped with different contents of Bi2O3, whose final molecular formula is Ba6-3x（Nd1-yBiy）8＋2xTi18O54 were investigated. It is indicated that the dielectric constant increases greatly whereas Q value（f0=4 GHz） decreases with the increase of Bi2O3 content. However, the temperature coefficient could be controlled below 0±30×10^-6/℃ in the experiment. These phenomena are related to the appearance of a new phase, Bi4Ti3O12, which has high dielectric constant. Also, that Bi^3＋（0.13 nm） substitutes for Nd^3＋（0.099 5 nm） will increase the unit cell volume, which will lead to the enlargement of the octahedron B site occupied by Ti^4＋. So the spontaneous polarization of Ti^4＋ ions will be strengthened. Besides, Bi^3＋ will fill up some vacancies which Ba^2＋ or Nd^3＋ ions leave in two A1 sites and four A2 sites. More positive ions polarize, which also contributes to higher dielectric constant. The samples got with the optimium properties are sintered at 1 200 ℃ for 4 h, when y=0.25, ε≈110, Q≈5 400（f0=4 GHz）, TCC=-4.7×10^-6/℃; When y=0.3, ε≈120, Q≈5 000（f0=4 GHz）, TCC=-24×10^-6/℃.     

Recovery of copper sulfate after treating As-containing wastewater by precipitation method

The solid sodium hydroxide neutralized acidic As-containing wastewater till pH value was 6. Green copper arsenite was prepared after copper sulfate was added into the neutralized wastewater when the molar ratio of Cu to As was 2:1 and pH value of the neutralized wastewater was adjusted to 8.0 by sodium hydroxide. The arsenious acid solution and red residue were produced after copper arsenite mixed with water according to the ratio of liquid to solid of 4:1 and copper arsenite was reduced by SO₂ at 60 °C for 1 h. The white powder was gained after the arsenious acid solution was evaporated and cooled. Copper sulfate solution was obtained after the red residue was leached by H₂SO₄ solution under the action of air. The results show that red residue is Cu₃(SO₃)₂·2H₂O and the white powder is As₂O₃. The leaching rate of Cu reaches 99.00% when the leaching time is 1.5 h, molar ratio of H₂SO₄ to Cu is 1.70, H₂SO₄ concentration is 24% and the leaching temperature is 80 °C. The direct recovery rate of copper sulfate is 79.11% and the content of CuSO₄·5H₂O is up to 98.33% in the product after evaporating and cooling the copper sulfate solution.     

Preparation and Characterization of Fe^3＋ -doped Nanometer TiO2 Photocatalysts

Fe^3＋ -doped nanometer TiO2 photocatalysts were prepared by sol-gel technique. TiO2 powders with different Fe^3＋ / Ti^4 ＋ molar ratios ranging from 0. 05% to 25% were synthesized by calcinating the gels in the temperature range of 200-600 ℃ . The effects of the content of iron ions and calcination temperature on the physical properties of the powders and their photocatalytic activities were examined by the photodecorapositon of methyl orange in sunlight. The results show that Fe dopant can decrease the temperature of nanatase-ratile transformation. The ideal photocatalytic property was achieved when the sample with an Fe^3＋ / Ti^4＋ ratio of 20 at% was calcined at about 300 ℃ for an hour, which is superior to that of commercial Degussa P-25. The optimum microstructure of the Fe-doped TiO2 for a high photocatalytic activity in sunlight is consisted of nanatase and ratile.     

米曲霉HDF-7蛋白酶的分离纯化及酶学性质研究

对米曲霉 HDF-7 所产蛋白酶进行分离纯化,经硫酸铵沉淀和凝胶过滤层析得到电泳纯的蛋白酶,经SDS-PAGE 电泳测定其相对分子质量约为30 KDa.该酶的最适反应温度为50℃,最适作用pH值为7.0,该酶在20℃时具有良好的热稳定性,在pH6.0～8.0的条件下酶是相对稳定的,Mn2+对该蛋白酶有明显的激活作用,Cu2+对该蛋白酶有强烈的抑制作用,Km值为78μg/mL,最大反应速度V max为6.29μg/min.     

Effect of Fe(III) impurity on the electrochemical performance of LiFePO<Subscript>4</Subscript> prepared by hydrothermal process

Lithium iron phosphate (LiFePO₄) was synthesized from LiOH, FeSO₄ and H₃PO₄ by a hydrothermal process at 180°C. The samples were characterized by X-ray diffraction, scanning electron microscopy and chemical analysis. Electrochemical performance of the samples was tested in terms of charge-discharge capacity and cycling behavior. The results indicated that Fe(III) impurity had obviously effect on the electrochemical properties of LiFePO₄, and the formation of Fe³⁺ was caused by the oxidation of Fe²⁺ in the dissolving and feeding processes accompanying the increase of pH value. It was found that the precipitation separation was effective in decreasing the content of Fe³⁺ in the solution of FeSO₄ and the sealed feeding was useful in preventing the conversion of Fe²⁺ to Fe³⁺. When the content of Fe³⁺ < 0.5 wt%, the hydrothermally synthesized LiFePO₄ calcined at 750°C with sucrose as carbon source exhibited an initial discharge capacity of 154.9 mAh·g⁻¹ at the rate of 0.1 C (1 C = 150 mA·g⁻¹) and the cycling retention rate could reach 98% after 50 cycles at room temperature.     

Preparation of magnetic chitosan nanoparticles and immobilization of laccase

The magnetic chitosan nanoparticles were prepared by reversed-phase suspension method using Span-80 as an emulsifier, glutaraldehyde as cross-linking reagent. And the nanoparticles were characterized by TEM, FT-IR and hysteresis loop. The results show that the nanoparticles are spherical and almost superparamagnetic. The laccase was immobilized on nanoparticles by adsorption and subsequently by cross-linking with glutaraldehyde. The immobilization conditions and characterizations of the immobilized laccase were investigated. The optimal immobilization conditions were as follows: 10 mL of phosphate buffer (0.1 M, pH 7.0) containing 50 mg of magnetic chitosan nanoparticles, 1.0 mg · mL⁻1 of laccase and 1% (v/v) glutaraldehyde, immobilization temperature of 4°C and immobilization time of 4 h. The immobilized laccase exhibited an appreciable catalytic capability (480 units · g⁻¹ support) and had good storage stability and operation stability. The K _m of immobilized and free laccase for ABTS were 140.6 and 31.1 μM in phosphate buffer (0.1 M, pH 3.0) at 37 °C, respectively. The immobilized laccase is a good candidate for the research and development of biosensors based on laccase catalysis. Funded by Key Project of National Science Foundation of China (No. 60537050) and the National Science Foundation of China (No. 60377032)     

氧化—絮凝调理对剩余污泥脱水性能的影响

针对污水处理厂污泥脱水难度大、运行成本高等问题,深入研究NaClO投加量、污泥混合液pH值以及在NaClO最佳投加量和污泥混合液最佳pH值下耦合聚合硫酸铁(PFS)和三氯化铁(FeCl₃)对污泥脱水性能的影响,以期获得氧化—絮凝调理对活性污泥脱水性能的影响机制。结果表明,在NaClO投加量为40 mg/g DS(绝干污泥)和污泥混合液pH值为3时,PFS耦合NaClO调理后的泥饼含水率和污泥比阻(Specific Cake Resistance,SRF)分别降至85.86%和4.74×10¹¹ m/kg;FeCl₃耦合NaClO调理后的泥饼含水率和污泥比阻分别降至86.36%和3.93×10¹¹ m/kg。调理后的污泥絮体粒径D50的大小关系为：NaClO+PFS>NaClO+FeCl₃>pH值>原泥>NaClO。显然,经过氧化—絮凝调理后的污泥絮体粒径明显增大,滤液中的有机质含量降低。氧化—絮凝调理可使活性污泥比阻显著降低,脱水性能显著改善。NaClO...     

Preparation and Performance of Si<Superscript>4+</Superscript>-doping Rod-shaped TiO<Subscript>2</Subscript> Powder by Nonhydrolytic Sol-gel Method

Titania (TiO₂) nanorod powder was prepared by nonhydrolytic sol-gel method using titanic chloride (TiCl₄) as titanium source, methylene dichloride (CH₂Cl₂) as solvent, absolute ethyl alcohol (CH₃CH₂OH) as oxygen donor. The effects of Si⁴⁺ doping on the TiO₂ nanocrystalline phase transformation temperature were systematically researched. The results showed that when the molar ratio of Ti⁴⁺ to Si⁴⁺ is 1 to1.3, TiO₂ prepared by calcination at 1100 °C for 1 hour exhibits rod shape and has good photocatalytic activity. Doping of Si⁴⁺ makes glass phase core-shell structure forming on the surface of anatase crystal particles, which can inhibit crystal phase transformation and raise the transformation temperature, making TiO₂ stable in anatase phase at 1200 °C.     

Dissolution kinetics of malachite in ammonia/ammonium sulphate solution

The dissolution kinetics of malachite was investigated in ammonia/ammonium sulphate solution. The effects of ammonia and ammonium sulphate concentration, pH, leaching time, reaction temperature, and particle size were determined. The results show that the optimum leaching conditions for malachite ore with a copper extraction more than 96.8% are ammonia/ammonium concentration 3.0 mol/L NH₄OH + 1.5 mol/L (NH₄)₂SO₄, liquid-to-solid ratio 25:1 mL/g, leaching time 120 min, stirring speed 500 r/min, reaction temperature 25 °C and particle size finer than 0.045 mm. The dissolution process of malachite with an activation energy of 26.75 kJ/mol is controlled by the interface transfer and diffusion across the product layer. A semi-empirical rate equation is obtained to describe the leaching process and the reaction orders with respect to concentration of ammonia and ammonium sulphate are 2.983 0 and 0.941 1, respectively.     

Structure and dielectric properties of ZnO and Nb<Subscript>2</Subscript>O<Subscript>5</Subscript> doped BaO-TiO<Subscript>2</Subscript> system microwave ceramics

The microwave dielectric properties and microstructure of BaTi4.3ZnyO9.6＋y ＋0.02 mol% SnO2＋0.01 mol% MnCO3＋x mol% Nb2O5（x=0-0.05, y=0-0.08） system ceramics were studied as a function of the amount of ZnO and Nb2O5 doped. Addition of （y=0-0.05） ZnO and （x=0-0.025） Nb2O5 enhanced the reactivity and decreased the sintering temperature effectively. It also increased the dielectric constant ε r and quality factor Q（=1/tan 8） of the system due to the substitution of Ti^4＋ ions with incorporating Zn^2＋and Nb^5＋ ions, which was analyzed by the reaction ZnO＋Nb2O5＋ 3 TiTxTi →ZnTi＋ 2NbTi＋3TiO2. When the system doped with （y=0.05） ZnO and （x=0.025） Nb205 were sintered at 1 160 ℃ for 6 h, the εr. Qf0 value and rfwere 36.5, 42 000 GHz, and＋1.8 ppm/℃, respectively, at 5 GHz.