Purification and characterization of extracellular chitinase from a novel strain Aspergillus fumigatus CS-01

Twelve samples derived from different locations in south central area of China are treated by enrichment and spread-plate technique for initial screening. Seven chitinase-producing strains are isolated. The chitinase present in the culture supernatant of strain CS-01 possesses the maximum activity of 0.118 U/mL. Analysis of the morphological feature and the ITS rDNA sequence reveals that strain CS-01 belongs to Aspergillus fumigatus. Production of the chitinase is regulated by a inducible way and the maximum activity appears at 36 h in colloidal chitin culture. Purification of the chitinase is carried out by salting out, gel filtrate chromatography and anion exchange chromatography sequentially. Native-PAGE and SDS-PAGE indicate that the chitinase from A. fumigatus CS-01 is a monomer with the relative molecular mass estimated to be 4.50×10⁴. Its maximum activity appears at pH 5 and 55 °C. The chitinase is stable at pH 4.0–7.5 and below 45 °C. Foundation item: Projects(50621063, 50674101) supported by the National Natural Science Foundation of China     

Methodology of factorial design deriving guidelines for simulation of growth curve and production of sugars by Spirulina (Arthrospira) maxima

It is practical, economic and sometimes essential to derive rules or conclusions by performing lesser runs of experiments. In this part, a methodology based on 2 ^f factorial design was brought up to derive guidelines to simulate growth curve and production of sugars by Spirulina (Arthrospira) maxima. The growth curve or accumulation process of sugars was idealized by sets of straight lines limited by phase transfers of growth or accumulation of sugars. Normal analyses of the critical values of the transfers were used to derive their linear relationships with the initial conditions of the experimental factors. These linear functions were called guidelines and were used to simulate the growth curve or accumulation of sugars. Generalization of the guideline technique was determined by the kinetic limitation of nutrient nitrogen or sulfur that was dependent upon their stoichiometric deficiency directly derived from their initial values in the medium. This method uses the initial conditions of culture and does not need measurements of concentrations of nitrate, sulfate and pigments during cultivation. It is a practical and useful alternative way to trace and predict approximately the growth curve and production of sugars by S. maxima. Foundation item: Scholarship for Ph. D. at FPMs, Belgium Biography of the first author: NIE Zhen-yuan, Engineer of biomedicine, born in 1963, majoring in biotechnology and bioengineering.     

Isolation and characterization of YNTC-1, a novel Alicyclobacillus sendaiensis strain

A heterotrophic acidothermophilic bacterial strain, YNTC-1, was isolated from an acidic hot spring in Tengchong, Yunan, China. YNTC-1 grows at pH value of 1.5-8.0 and temperature of 40-70 ℃, with optimal pH and temperature at 3.0 and 55 ℃, respectively. The cells of the strain are in shape of short rod, with 1.0-1.2 μm in length and 0.7-0.8 μm in diameter, and with distinct spores at both poles of each cell. The predominant fatty acids in cellular membrane of the strain are C18：1 ω7c. 16s rRNA gene analysis reveals that this strain is closely related to Alicyclobacillus sendaiensis, with over 99% sequence similarity. Based on phenotypic and genotypic analyses, YNTC-1 is identified as a member ofA. sendaiensis. Considering some important morphological and biochemical differences between strain YNTC-1 and A. sendaiensis ATCC 27009T, YNTC-1 may be proposed to be a novel subspecies of A. sendaiensis. However, this viewpoint has to be confirmed by further studies. Co-bioleaching of pyrite and chalcopyrite with strain YN22, Sulfobacillus thermosulfidooxidans, shows that strain YNTC-1 has no evident influence on bioleaching rates of these two sulphide minerals.     

木糖发酵产乙醇丝状真菌的鉴定及发酵特性

针对目前对丝状真菌的木糖发酵研究较少的现状,应用杜氏管发酵法初筛和发酵测定法复筛对不同环境的土壤样品进行菌株的筛选,并采用显微镜观察和18S rRNA序列扩增分析对菌种进行鉴定;用重铬酸钾法对菌株的发酵特性进行研究.结果表明：筛选到一株能发酵木糖的丝状真菌,命名为cs-28;经形态学和生物学鉴定为尖孢镰刀菌（Fusar...     

Isolation, identification and characterization of cadmium-resistant Pseudomonas aeruginosa strain E1

Strain E₁ with resistance to 18 mmol/L cadmium (Cd), isolated from Cd-contaminated soil was identified by morphological observation, biochemical and physiological characterization and 16S rDNA sequence analysis. The resistance to heavy metals Cd, Cu, Co, Mn, Pb, Zn and 12 antibiotics was examined. The ability of removing Cd from solution was studied. The characterizations show that strain E₁ is affiliated to Pseudomonas aeruginosa (P. aeruginosa). Strain E₁ has high resistance to heavy metals and the order is found to be Cd>Mn>Zn>Cu>Pb>Co in solid media. Strain E₁ also exhibits the resistance to 12 antibiotics. Both living and non-living cells of strain E₁ can remove Cd from solution, and living cell has better biosorption than non-living cell. Foundation item: Project (50621063) supported by the National Natural Science Foundation of China; Project (2004CB619204) supported by the Major State Basic Research and Development Program of China     

Structural and optical characteristics of Al x Ga1- x N/AlN superlattice

AlN/Al_0.3Ga_0.7N superlattices were grown on (0001) sapphire substrate by metal-organic chemical vapor deposition (MOCVD). The superlattice period varies from 6 to 30. The layer thickness of different period stack was designed. GaN or AlGaN template was employed for growing AlN/AlGaN superlattices. Reflectivity, SEM, AFM and XRD data of the Al _x Ga_1-x N/AlN superlattices are presented. It is found that the templates used have an intensive impact on surface roughness and interfacial properties of following AlN/AlGaN superlattices. The result of atomic force microscopy indicates that AlN/AlGaN superlattices grown on GaN template exhibit quasi-two-dimensional growth mode. The resulting superlattice has a smooth surface morphology and distinct interface. No crack is observed in the area of a 2-inch wafer. Supported by the Special Funds for Major State Basic Research Project (973 Project) (Grant No. 2006CB6049), the Hi-tech Research Project (Grant Nos. 2006AA03A103, 2006AA03A118, and 2006AA03A142), the National Natural Science Foundation of China (Grant No. 60676057), and the Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20050284004)     

纳米塑料对大型 氵 蚤 摄食及生长繁殖的影响

水环境中的纳米塑料（NPs）污染已成为全球性的环境问题。大型溞（Daphnia magna）作为淡水中重要的初级消费者之一,常被运用于基于生物操纵的富营养化水体修复,但关于NPs对大型溞摄食行为的影响尚不清晰。以大型溞和聚苯乙烯纳米塑料（PSNPs,1 000 nm）为研究对象,探究了大型溞21 d内对产毒铜绿微囊藻（Toxic Microcystis aeruginosa）和斜生栅藻（Scenedesmus obliquus）摄食倾向的变化及其生理响应。结果表明,以单一产毒铜绿微囊藻作为食物来源时,大型溞受到的发育和生殖毒性最强;与对照组（单一斜生栅藻饲喂）相比,高浓度产毒铜绿微囊藻组大型溞体内超氧化物歧化酶（SOD）活性和丙二醛（MDA）含量分别升高至对照组的3.97倍和4.55倍,总产卵次数和体长分别降低了73%和13%,且大型溞对产毒铜绿微囊藻的滤食率呈随时间延长而升高的趋势。但在PSNPs（3.56 mg/L）暴露下,在初始藻密度为微囊藻:栅藻为1:9和微囊藻:栅藻为2.5:7.5处理组中,大型溞的滤食能力都显著下降;对照组添加PSNPs后,大型溞对斜生栅藻的滤食率降低了32%。在产毒铜绿微囊藻和斜生栅藻共培养体系中,大型溞对产毒铜绿微囊藻的滤食率比对照组降低了66%,缓解了大型溞所受的发育和生殖毒性,但不利于降低微囊藻的生物量。     

On the calculation of stress intensity factor K for frame components

The stress intensity factorK in the tip of crack which is in the corner of the frame component has been calculated indirectly by means of numeric calculation ofJ Integral. Some laws and relationships among the stress intensity factorK, the applied loads and the crack length for this kind of components have been discovered for the first time. The calculating formula forK has been deduced, the criticalK has been calculated with the formula, that is 5 811.56–6 122.58 MPa · mm^1/2. The conclusions reached in this paper are of great referential and practical value for simplifying the calculation of stress intensity factorK for this type of components. Project supported by Technological Development Foundation of the Nonferrous Metal Industry Corporation of China Synopsis of the first author Liu Yilun, Doctor, associate professor, born in Oct. 30, 1955. Research areas are fatigue strength of component and the technology of continuous casting for non-ferrous metal.     

Speciation of chromium in soil inoculated with Cr（Ⅵ）-reducing strain, Bacillus sp. XW-4

Cr(VI)-amended soil was inoculated with Cr(VI)-reducing strain, Bacillus sp. XW-4 and incubated at 28 °C in an incubator. Cr(VI) reduction, available Cr and Cr fraction in soils were studied. The results show that addition of Bacillus sp. XW-4 can promote Cr(VI) reduction, but inoculation of this strain has a negative effect on the decrease of available Cr content in soil. In controls (without this strain) amended with 100 and 200 mg/kg of Cr(VI), Cr(VI) contents decrease to about 41 and 92 mg/kg respectively after incubation of 4 d, while in soil inoculated with XW-4, Cr(VI) contents decrease to about 18 and 60 mg/kg, respectively. The content of available Cr in soils with inoculation of XW-4 is higher than that in controls. Chromium is partitioned into water soluble Cr, exchangeable Cr, precipitated Cr, Cr bound to organics and residual Cr. The highest content of Cr is observed in residual form and water soluble Cr is not detected for all treatments after 42 d, but the soils inoculated with Bacillus sp. XW-4 contain higher content of exchangeable Cr and lower content of precipitated Cr than the soil without the inoculum. Inoculation of Bacillus sp. XW-4 can increase chromium activity in soils. Foundation item: Project(20050532009) supported by the Doctoral Foundation of Ministry of Education of China; Project supported by Program for Changjiang Scholars and Innovative Research Team in University     

嗜酸性硫杆菌脱除废镀铝膜表面铝的工艺参数及效果研究

镀铝膜袋是电子产品等的常用包装物,使用量大,废弃后铝影响了塑料膜的循环使用.由于缺乏有效和低成本的方法,镀铝膜中的金属铝未完全从镀铝膜中提取出来.因此,需开发新的方法来提高铝塑分离效率,降低成本,提高废镀铝膜的再生利用率.通过利用嗜酸菌的产酸能力等作用溶解铝进行铝塑分离,对包装用废镀铝膜表面铝进行微生物浸出实验研究,探...     

多次采样m序列法辨识LTI脉冲响应计算方法

研究一个时钟周期内多次采样条件下m序列法辨识线性时不变系统脉冲响应的计算方法,推导出脉冲响应序列与m序列周期、幅度及采样率之间的关系表达式。将双极性m序列信号的自相关特性进行均匀抽样,写成全周期内的统一表达式,代入维纳-何甫方程,再利用循环右移矩阵将脉冲响应用输入、输出采样序列表达出来。在matlab平台上对算法进行仿真实验,结果证明这种算法是正确的。     

Structural stability and magnetism of metastable Ni-Pt intermetallic compounds studied by ab initio calculation

The self-consistent electronic structure calculations were carried out with the accurate frozen-core full-potential projector augmented-wave method on 13 Ni-Pt intermetallic compounds of simple crystalline structures, i.e. A15, D0₁₉, D0₃ and L1₂ Ni₃Pt and NiPt₃, and α-NiAs, B1, B2, L2 _a , and L1₀ NiPt. The calculations reveal that the L1₂ Ni₃Pt, L1₀ NiPt and L1₂ NiPt₃ are energetically more stable than their respective competitive structures, indicating that the three structures may be formed in some appropriate conditions. The obtained results match well with the experimental observation or other theory predictions. It is found that there is hybridization between Ni 3d and Pt 5d states, which may significantly affect the structural stability and magnetism of metastable Ni-Pt intermetallic compounds. Supported by the National Natural Science Foundation of China (Grant Nos. 50531040, 50871058), the Ministry of Science and Technology of China (Grant No. 2006CB605201), and the Administration of Tsinghua University     

New development of hydraulic fracturing technique for in-situ stress measurement at great depth of mines

In-situ stress measurement using the hydraulic fracturing technique was made at Wanfu Coal Mine in Shandong Province, China. To solve problems caused by great measuring depth and extra thick overburden soil layers in the mine, a series of improved techniques were developed for the traditional hydraulic fracturing technique and equipment to increase their pressure-enduring ability and to ensure safe and flexible removal of the sealing packers with other experimental apparatus. Successful in-situ stress measurement at 37 points within 7 boreholes, which were mostly over 1000 m deep, was completed. Through the measurement, detailed information of in-situ stress state has been provided for mining design of the mine. The improved hydraulic fracturing technique and equipment also provide reliable tools for in-situ stress measurement at great depth of other mines.     

Thermodynamics and kinetics analysis of in-situ synthesizing AIN

AIN powders were prepared by in-situ synthesis technique. It is a reaction of binary molten Al−Mg alloys with highly pure nitrogen. It was confirmed through thermodynamics calculation that Mg element in Al−Mg alloys can decrease oxygen content in the reacting system. Thus, nitridation reaction can be performed to form AIN. Moreover, an analysis of kinetics shows that the nitridation reaction of Al−Mg alloys can be accelerated and transferred rapidly with the increment of Mg content.     

铜绿微囊藻衰亡过程中产甲烷动态及关键影响因子

为探究铜绿微囊藻水华自然衰亡和水华堆积区藻快速衰亡对CH₄释放的影响,构建了室内模拟实验,研究了铜绿微囊藻自然衰亡和快速衰亡过程中水环境因子和CH₄、CO₂气体释放通量的变化。结果表明：高密度铜绿微囊藻衰亡中水环境因子和产气的变化遵循相似的时间模式,且衰亡对CH₄和CO₂的产生有显著的促进作用。自然衰亡和快速衰亡的CH₄累积释放量分别为对照组的22.80倍37.72倍,CO₂累积释放量分别为对照组的5.36倍和4.03倍。自然衰亡与快速衰亡的总碳（C）释放量差异不大,但快速衰亡释放的气体组分中CH₄的占比是自然衰亡的1.86倍。相关性分析表明,溶解性有机碳（DOC）是铜绿微囊藻衰亡中影响CH₄和CO₂释放的主导因子,且DOC中的芳香蛋白类物质和溶解性微生物代谢产物是CH₄和CO₂产生的主要底物来源。     

二氧化碳管道运输系统优化模型及其应用

二氧化碳捕集利用与封存(CCUS)作为能够实现煤化工行业温室气体大规模减排的前沿技术,已成为当前研究热点.而管道运输是该技术得以实施的关键环节,高昂运输成本是影响该技术大规模推广的主要因素.因此,通过开发煤化工二氧化碳(CO_2)捕集压缩、管道运输系统优化模型,实现CO_2管道运输系统内关键环节的工艺和技术优化配置,降低捕集压缩、运输及注入整个系统的总成本.将模型初步应用于陕西延长榆林煤化工CCUS项目,结果表明:当封存区域CO_2封存需求量小,而且能够在封存现场提供方便的液化压缩设备时,榆林能化煤化工企业可以采用气相压缩输送方案,并结合封存地点液化加压注入;对于大规模CO_2封存及运输需求时,推荐超临界/密相CO_2输送,能够有效减少封存区再次加压环节的成本,从而使整个流程更为经济.     

Homology modeling and evolutionary trace analysis of superoxide dismutase from extremophile Acidithiobacillus ferrooxidans

The gene sod in Acidithiobacillus ferrooxidans may play a crucial role in its tolerance to the extremely acidic, toxic and oxidative environment of bioleaching. For insight into the anti-toxic mechanism of the bacteria, a three-dimensional (3D) molecular structure of the protein encoded by this gene was built by homology modeling techniques, refined by molecular dynamics simulations, assessed by PROFILE-3D and PROSTAT programs and its key residues were further detected by evolutionary trace analysis. Through these procedures, some trace residues were identified and spatially clustered. Among them, the residues of Asn38, Gly103 and Glu161 are randomly scattered throughout the mapped structure; interestingly, the other residues are all distinctly clustered in a subgroup near Fe atom. From these results, this gene can be confirmed at 3D level to encode the Fe-depending superoxide dismutase and subsequently play an anti-toxic role. Furthermore, the detected key residues around Fe binding site can be conjectured to be directly responsible for Fe binding and catalytic function. Foundation item: Project(2004CB619201) supported by the National Basic Research Program of China; Project (50321402) supported by the National Natural Science Foundation of China     

Comparative analysis of chemical components between barks and leaves of Eucommia ulmoides Oliver

The chemical components of the essential oils in the barks and leaves of Eucommia ulmoides Oliver were analyzed and compared by chromatograms and mass spectra technique, heuristic evolving latent projections (HELP), alternative moving window factor analysis (AMWFA) algorithms and normalization method based on the peak areas; the flavones in the barks and leaves of Eucommia ulmoides Oliver were separated on an ODS column by gradient elution carried out with the flow phase consisting of water, methanol and phosphoric acid (0.1%), and their contents were quantitatively determined by standard curve method and diode array detection (DAD) at 362 nm. The results show that 68 and 73 compounds respectively from essential oils of the barks and leaves of Eucommia ulmoides Oliver are identified, and there are 33 mutual compounds among 108 compounds determined. The total contents of these volatile components of the two samples possess 92.9% and 97.75% of the gross of the relevant essential oils, respectively; the contents of the rutin, quercetin and kaempferol in the barks and leaves of Eucommia ulmoides Oliver are 0.016 9, 0.003 6, 0.002 1 and 0.064 4, 0.030 2, 0.010 0 mg/g, respectively, and the determination recoveries are 95.2%–106.2%. The comparative analysis shows that for the barks and leaves of Eucommia ulmoides Oliver, there are significant differences in their components of the relevant essential oils and flavones. Foundation item: Project(20235020) supported by the National Natural Science Foundation of China     

Oxidation kinetics and high temperature in-situ observation of the oxidation behaviour of NbSi2 at 1023 K

By using high temperature optical microscopy, oxidation behaviors of poly-and single crystalline NbSi₂ were observed in-situ at 1023 K. The effects of micro-cracks, porosity and grain boundary on the oxidation behavior of NbSi₂ have been studied. The results indicate that new cracks initiate and extend from the pre-existing cracking areas in the arc-melted poly-crystalline specimen, leading to fragmentation after 220 min at 1023 K. However, although pores and grain boundary are the preferential oxidation site, they do not directly lead to fragmentation during oxidation, indicating that the pre-existing cracks in specimen are the key reason to pesting. The oxidation kinetics of the studied NbSi₂ specimens corresponds well with the in-situ observation.