Spontaneous formation of tubular microstructure vesicle from PTA／SDS system

Spontaneous vesicle formation and transformation of vesicle to tubular microstructure have been observed in aqueous mixtures of tri-(n-dodecyl-dimethyl-hydroxy-propylammonium chloride) phosphate (PTA) and sodium dedecyl sulfate (SDS), which is supported by negative-staining transmission electron microscopy (TEM), scan electron microscopy (SEM) and dynamic light scattering (DLS). Spherical vesicles aggregate to tubular microstructures with their diameters and lengths respectively of about 100 and 7000 nm in the freshly prepared sample at the molar ratio of PTA/SDS=3/7 and a total surfactant concentration of 0.01 mol/L. The diameter, the length and the quantity of tubular structures all increase with the increase of the total concentration of surfactant and the sample aging.     

Effects of medium nutrition on cell growth and isocamptothecin A and B production by suspension cell culture of Camptotheca acuminata

The effects of initial sucrose concentration, nitrate to ammonium ratio, total N concentration and phosphate concentration in medium on cell growth and isocamptothecin A and B synthesis by suspension call culture of Camptotheca acuminata were investigated in 250 mL shake flasks. 30 g L^-1 sucrose concentration was beneficial to secondary metabolites synthesis. The cell growth and metabolites synthesis were also affected by the ratio of NO3^-/NH4^＋ , and nitrate was tavourable for cell growth. The maximum dry weight was achieved when nitrate was used as the sole N souree. The effect of total initial N on the cell cultures was also investigated with NO3^-/NH4^＋ ratio of 1 ： 2. The final dry cell weight was similar throughout culture period and 50 mM initial N was favourable for secondary metabolite synthesis. 50 mM initial phosphate concentration facilitated both cell growth and secondary metabolites synthesis.     

Operational and structural aspects of a vapor-feed semi-passive direct methanol fuel cell supplied with concentrated methanol

Direct methanol fuel cell （DMFC） has great potential to replace the traditional battery in the field of portable power sources. This study investigates the operational and structural aspects of a vapor-feed semi-passive DMFC supplied with concentrated methanol. The effec tiveness of using vaporous methanol to improve the cell performance is experimentally validated. Results indicate that there exits an optimal value of methanol concentration that favors both methanol supply and control of methanol crossover （MCO）. With the increase in vaporization temperature, the cell performance can be enhanced. Based on the traditional structural design, a sintered porous metal plate is further used to depress the impact of MCO so that the cell performance can be significantly improved at a relatively higher methanol concentration. This is of great importance to enhance the energy density and operating duration for portable applications. The mechanisms related to the performance behaviors are discussed in detail.     

Medium optimization for enhanced production of cytosine-substituted mildiomycin analogue （MIL-C） by Streptoverticillium rimofaciens ZJU 5119

Cytosine-substituted mildiomycin analogue （MIL-C） was produced effectively by supplementing cytosine into the culture of Streptoverticillium rimofaciens. In order to improve the yield of MIL-C, statistically-based experimental designs were applied to optimize the fermentation medium for S. rimofaciens ZJU 5119. Fifteen culture conditions were examined for their significances on MIL-C production using Plackett-Burman design. The Plackett-Burrnan design and one-variable-at-a-time design indicated that glucose and rice meal as the complex carbon sources, and peanut cake meal and NH4NO3 as the complex nitrogen sources were beneficial for MIL-C production in S. rimofaciens ZJU 5119. The results of further central composition design （CCD） showed that the optimal concentration of glucose, rice meal and peanut cake meal were 18.7 g/L, 64.8 g/L and 65.1 g/L, respectively. By using this optimal fermentation medium, the MIL-C concentration was increased up to 1336.5 mg/L, an approximate 3.8-fold improvement over the previous concentration （350.0 mg/L） with un-optimized medium. This work will be very helpful to the large-scale production of MIL-C in the future.     

Hydrolysate of corn starch saccharified with a dual-enzyme system and the effect on the crystallization of itaconic acid when used in fermentation

An improved process of hydrolysis of corn starch was adopted in the production of itaconic acid （IA）, the aim was to decrease the unfermentable reducing sugar （RS） in the medium from the beginning of the fermentation and to increase the crystallization efficiency of IA from the fermentation broth. The glucose （GS） syrups saccharified by several combinations of glucoamylase and pullulanase were investigated and used as the carbohydrate source of the fermentation medium for the spore-initiated submerged fermentations experiments. Compared with the conventional process （with pullulanase controlled）, the improved process decreased th.e RS residue in the fermentation broth from 3.01g/L to 1.35g/L and from 4.25g/L to 3.25g/L when the original RS of the medium were 100 and 120g/L, respectively. The crystallization efficiency of IA increased from 65% to 78.8% and from 69.58% to 82.81% with the original RS being 100 and 120g/L, respectively.     

Mixotrophic Cultivation of Tetraselmis sp. - 1 in Airlift Photobioreactor

Tetraselmis sp. -1 is a new microalgae strain constructed by cell fusion technique. In this paper, the mixotrophic cultivation of Tetraselmis sp.-1 in airlift photobioreactor is investigated.Firstly, the paper calculates the light attenuation in the mixotrophic medium, and sets the light attenuation model. Secondly, it uses the same dissolved oxygen coefficient (Ka) of flask culture to select the aeration of bioreactor. Finally, it sets the growth kinetic model, production (chlorophyll - a and total lipid) kinetic models and substrate (glucose) consumption kinetic model of Tetraselmis sp. - 1 in airlift photobioreactor.     

硫化碱烟气脱硫的小试实验

A novel technique of flue gas desulphurization (FGD) using industrial sodium sulfide as absorbent is described to remove SO2 in flue gas. The FGD byproduct in this novel technique is sodium thiosulfate (Na2S2O3·5H2O,Hypo) which can be used as chemical raw material. Optimal operating parameters about this technique have been determined. In order to enhance productive efficiency of sodium thiosulfate,EDTA disodium additive is added into absorption solution to prevent oxidation of sodium thiosulfate. Its optimal concentration is 0.02 wt. %. The pH value of absorption solution is set in the range of 5～6.5. Experimental results show that SO2 removal efficiency averagely reach 98.72 %. The highest productive efficiency of sodium thiosulfate reaches 83.24 %.The sodium thiosulfate formed during FGD can be separated from saturated absorbent by filtration,concentration and crystallization. The filtrate after separating sodium thiosulfate will be reused as SO2 absorbent by replenishing some fresh sodium sulfide.     

Microbial Transformation of Acetophenone to 2—Phenylethanol

Microorganisms are commonly used to transform chemicals to chiral compounds. Pseudomonas cepacia 1813, Pseudomonas stutzeri 1317, Saccharomyces cerev isiae 1912, and 5 Escherichio coil strainswere used to transform acetophenone to 2-phenylethanol. The results show that the E. coli strains have the poorest biotransformation ability. P. stutzeri 1317 provides the best transformation ability with a transformation rate of 30% achieved with either whole or broken P. stutzeri 1317 cells for a reaction pH of 8. 2 and an initial acetophenone concentration of 2 g/L. An acetophenone concentration of 10 g/L strongly inhibits the biotransformation for a pH of 8. 2. Crude alcohol dehydrogenase obtained from S. cerevisiae 1912 transforms acetophenone to 2-phenylethanol when nicotinamide adenine dinucleotide reduced (NADH) is added.     

An experiment on multibubble sonoluminescence spectra in sodium chloride solution

We investigated experimentally the spectra of MBSL in sodium chloride water solution with krypton as dissolved gas. We observed and compared the spectra of hydroxyl ion at 310 nm and that of sodium atom at 589 nm. It has been found that under the same experimental condition, the intensity of sodium atom spectra is obviously higher than that of the hydroxyl ion spectra, and is more sensitive to the experimental condition. The krypton content, the concentration of sodium chloride solution, and the driving sound pressure obviously affect the spectra intensity in certain range.     

Zinc bioleaching from an iron concentrate using Acidithiobacillus ferrooxidans strain from Hercules Mine of Coahuila,Mexico

The iron concentrate from Hercules Mine of Coahuila,Mexico,which mainly contained pyrite and pyrrhotite,was treated by the bioleaching process using native strain Acidithiobacillus ferrooxidans (A.ferrooxidans) to determine the ability of these bacteria on the leaching of zinc.The native bacteria were isolated from the iron concentrate of the mine.The bioleaching experiments were carried out in shake flasks to analyze the effects of pH values,pulp density,and the ferrous sulfate concentration on the bioleaching process.The results obtained by microbial kinetic analyses for the evaluation of some aspects of zinc leaching show that the native bacteria A.ferrooxidans,which is enriched with a 9K Silverman medium under the optimum conditions of pH 2.0,20 g/L pulp density,and 40 g/L FeSO4,increases the zinc extraction considerably observed by monitoring during15 d,i.e.,the zinc concentration has a decrease of about 95% in the iron concentrate.     

中国红豆杉悬浮细胞固定化培养生产紫杉醇

对海藻酸钠包埋法固定中国红豆杉悬浮细胞的条件进行研究,建立了一套合适的固定化操作条件,即海藻酸钠浓度为３０ｇ／Ｌ,聚乙烯醇（ＰＶＡ）浓度为８０ｇ／Ｌ,ＣａＣｌ２浓度为２０ｇ／Ｌ,包埋密度为０．２ｋｇ／Ｌ,接种密度为０．１ｋｇ／Ｌ．在此基础上,对中国红豆杉细胞固定化培养的培养基进行了优化,结果表明,从红豆杉树皮中分离出的真菌培养物作为诱导物能限制细胞生长,且明显促进紫杉醇合成,并诱导紫杉醇分泌到培养液中．在培养基中适量地添加前体亦能提高紫杉醇的产量．对红豆杉细胞固定化培养中紫杉醇合成与分泌进行了动力学研究．     

双载体固定化中国红豆杉细胞的初步研究

对采用海藻酸钠和聚乙烯醇（ＰＶＡ）混合的双勒体包埋中国红豆杉悬浮细胞的条件进行了初步研究,建立了一套合适的国家化细胞条件,海藻酸钠浓度为３０ｇ／Ｌ,聚乙烯醇（ＰＶＡ）浓度为７０ｇ／Ｌ,ＣａＣｌ２浓度２０／Ｌ,包埋浓度为０．１８ｇ／Ｌ,接种密度为０．１２ｇ／Ｌ,在此基础上,对中国红豆杉细胞固定化２的培养基进行了优化,实验结果表明,从红豆杉树皮中分离出的真菌物作为诱导物能限制细胞生长,且明显促进紫杉醇     

纳滤膜脱除高粘度两性表面活性剂中的盐

采用纳滤膜考察了操作压力、不同的料液浓度、流量改变和浓缩过程对两性表面活性剂N,N-二甲基十二烷基甜菜碱（BS-12）中盐的脱除和BS-12浓缩效果的影响。实验结果表明：在操作压力2.5MPa和料液流量为583L／h下,对30％BS-12稀释后的BS-12浓度144g／L和氯化钠浓度39.2g／L料液进行纳滤膜脱盐浓缩,BS-12的截留率达到95％以上,氯化钠除盐率90％以上,可获得含盐量低于1％的BS-12,因而具有实际应用价值。     

海洋小球藻（Chlorella sp.）高密度培养条件优化研究

为提高小球藻（Chlorella sp.）的生物量,须对f/2配方培养基进行响应面优化。首先须确定小球藻培养基的最佳pH值和盐度。在此基础上,利用Plackett-Burman设计方案筛选出影响小球藻生长的3个主要因素分别为NaHCO3、KNO3和维生素B12,然后通过 Box-Behnken 设计试验确定这3个主要因素的最佳质量浓度参数。结果表明,当培养基组成为:NaHCO3 0.93 g/L、MgSO4 0.40 g/L、KNO3 0.46 g/L、K2HPO4 0.020 g/L、维生素B1 0.60 mg/L、维生素B12 1.8 μg/L、生物素 2.0 μg/L时,小球藻经实验室培养72 h后的生物量达到4.5×107个/mL,较优化前提高了32.5%。     

红豆杉细胞植板方法的研究

在红豆杉细胞植板中,适宜的培养基是优化的ＭＳ培养基,其中ＮＡＡ浓度为０．５ｍｇ／Ｌ,６ＢＡ浓度为０．５ｍｇ／Ｌ;培养细胞生长周期约４０ｄ;培养基中最优碳源浓度是：蔗糖３０ｇ／Ｌ、葡萄糖１０ｇ／Ｌ．无机盐最佳浓度是：ＮＨ＋４１０ｍｍｏｌ／Ｌ,ＮＯ－３４０ｍｍｏｌ／Ｌ,ＰＯ３－４１．２５ｍｍｏｌ／Ｌ．研究表明,培养基的ｐＨ值与植板率密切相关．氨基酸及维生素等有机成分能明显促进细胞生长．来自细胞悬浮培养物的条件培养基能显著地促进红豆杉培养细胞的单细胞在低密度植板时的克隆形成     

广西北海凡纳滨对虾养殖池塘叶绿素a和微藻的变化研究

于不同养殖时间,采集广西北海市3口凡纳滨对虾（Litopenaeus vannamei）养殖池塘水样,调查养殖水中叶绿素a浓度和微藻组成。叶绿素a浓度用分光光度三波长法测定,微藻分类计数用镜检法进行,微藻多样性分析用Shannon-Wiener多样性指数、Pielou种类均匀度指数和种类优势度指数进行。结果表明,3口池塘叶绿素a的浓度养殖前期低,在10.0μg/L以内,养殖中期增长迅速,养殖后期达到150.0μg/L;微藻细胞密度在养殖前期低于20×106cells/L,养殖后期高于100×106cells/L;微藻多样性指数和均匀度指数皆为养殖前期高,养殖中后期逐渐降低,多样性指数0.98～3.15,均匀度指数0.28～0.82;在养殖前期,微藻的种类较多,优势种是硅藻和绿藻,养殖中后期种类减少,优势种是绿藻、蓝藻和甲藻。     

黑木耳的富硒发酵

本实验以亚硒酸钠（Na2 SeO3）为硒源对黑木耳进行富硒发酵,以获得富硒黑木耳发酵液,为有机硒多糖等开发利用提供依据.用3种不同碳氮源培养基26℃于200rpm进行液体发酵,在不同时间测定黑木耳菌丝体多糖含量和生物量,确定了最优培养基（每升）为葡萄糖20g,豆饼粉5g,硫酸镁0.5g,磷酸二氢钾2g.在优选培养基中通过添加不同浓度的亚硒酸钠对黑木耳进行富硒发酵.结果与不添加亚硒酸钠黑木耳发酵液相比,在硒浓度为10-50mg/L时,黑木耳菌丝体的硒含量和生物量及发酵液多糖含量均随硒浓度的增加而提高;在50mg/L时,硒含量、生物量和多糖含量达最高,分别为10.48μg/g、9.37g和L20.3g/L;当亚硒酸钠浓度高于50mg/L时,菌丝体硒含量降低,生物量、多糖含量亦下降.结果表明,黑木耳具有较好富硒能力,但培养基中亚硒酸钠的浓度会影响发酵液中多糖含量和黑木耳菌丝体的富硒效果.与不添加亚硒酸钠黑木耳相比,添加适量亚硒酸钠有利于黑木耳菌丝对硒的吸收利用,并可促进黑木耳生长和多糖含量的提高;但过量添加,则可抑制黑木耳生长并降低多糖含量和对硒的利用率.     

一株堆肥高效解磷菌的筛选、鉴定及其溶磷特性

磷是植物必需的营养元素之一,但大多数耕地土壤中磷素易与Ca2+、Fe3+、Fe2+、Al3+等结合成无效态磷,植物难以直接吸收利用.解磷微生物可活化难溶性磷,将其接种于堆肥,有助于提高堆肥产品磷素植物可利用程度.从鸡粪好氧堆肥中筛选获得高效解磷细菌,为生物强化富磷堆肥的制备提供菌种.利用NBRIY培养基初筛获得解磷菌,...     

葡萄糖对莱茵衣藻生长和产氢的影响

通过在莱茵衣藻的培养基中添加葡萄糖,考察了葡萄糖对莱茵衣藻生长及产氢的影响。结果表明,在Tris Acetate Phosphate (TAP)培养基中添加葡萄糖对莱茵衣藻生长有利,最佳葡萄糖浓度为03g/L,藻细胞数和叶绿素浓度分别提高了12.8％和16.4％。在产氢培养基中,添加葡萄糖对莱茵衣藻产氢也有促进作用,氢气产量提高了27％。     

离子交换色谱流动相组成对核糖核酸酶的折叠影响

用离子交换色谱法（IEC）研究了还原变性核糖核酸酶（RNase A）折叠过程中，复性缓冲液种类及pH值、流动相中脲浓度及盐种类对还原变性核糖核酸酶复性的影响。发现pH为弱碱性，用PBS作为缓冲液能提高复性效率；当流动相中含有2．0mol／L脲时复性产率较高；洗脱剂用NaCl时活性回收率较高。