Purification and characterization of an alkaline protease from <Emphasis Type="Italic">Micrococcus</Emphasis> sp. isolated from the South China Sea

Protease is wildly used in various fields, such as food, medicine, washing, leather, cosmetics and other industrial fields. In this study, an alkaline protease secreted by Micrococcus NH54PC02 isolated from the South China Sea was purified and characterized. The growth curve and enzyme activity curve indicated that the cell reached a maximum concentration at the 30th hour and the enzyme activity reached the maximum value at the 36th hour. The protease was purified with 3 steps involving ammonium sulfate precipitation, ion-exchange chromatography and hydrophobic chromatography with 8.22-fold increase in specific activity and 23.68% increase in the recovery. The molecular mass of the protease was estimated to be 25 kDa by SDS-PAGE analysis. The optimum temperature and pH for the protease activity were 50°C and pH 10.0, respectively. The protease showed a strong stability in a wide range of pH values ranging from 6.0–11.0, and maintained 90% enzyme activity in strong alkaline environment with pH 11.0. Inhibitor trials indicated that the protease might be serine protease. But it also possessed the characteristic of metalloprotease as it could be strongly inhibited by EDTA and strongly stimulated by Mn²⁺. Evaluation of matrix-assisted laser desorption ionization/time-of-flight MS (MALDI-TOF-TOF/MS) showed that the protease might belong to the peptidase S8 family.     

Influence of white spot syndrome virus infection on hepatopancreas gene expression of ‘Huanghai No. 2’ shrimp (<Emphasis Type="Italic">Fenneropenaeus chinensis</Emphasis>)

To elucidate the molecular response of shrimp hepatopancreas to white spot syndrome virus (WSSV) infection, microarray was applied to investigate the differentially expressed genes in the hepatopancreas of ‘Huanghai No. 2’ (Fenneropenaeus chinensis). A total of 59137 unigenes were designed onto a custom-made 60K Agilent chip. After infection, the gene expression profiles in the hepatopancreas of the shrimp with a lower viral load at early (48–96 h), peak (168–192 h) and late (264–288 h) infection phases were analyzed. Of 18704 differentially expressed genes, 6412 were annotated. In total, 5453 differentially expressed genes (1916 annotated) expressed at all three phases, and most of the annotated were either up- or down-regulated continuously. These genes function diversely in, for example, immune response, cytoskeletal system, signal transduction, stress resistance, protein synthesis and processing, metabolism among others. Some of the immune-related genes, including antilipopolysaccharide factor, Kazal-type proteinase inhibitor, C-type lectin and serine protease encoding genes, were up-regulated after WSSV infection. These genes have been reported to be involved in the anti-WSSV responses. The expression of genes related to the cytoskeletal system, including β-actin and myosin but without tubulin genes, were down-regulated after WSSV infection. Astakine was found for the first time in the WSSV-infected F. chinensis. To further confirm the expression of differentially expressed genes, quantitative real-time PCR was performed to test the expression of eight randomly selected genes and verified the reliability and accuracy of the microarray expression analysis. The data will provide valuable information to understanding the immune mechanism of shrimp’s response to WSSV.     

Loading Rate Dependence of Tensile Strength Anisotropy of Barre Granite

Granitic rocks usually exhibit strongly anisotropy due to pre-existing microcracks induced by long-term geological loadings. The understanding of the rock anisotropy in mechanical properties is critical to a variety of rock engineering applications. In this paper, Brazilian tests are conducted statically with a material testing machine and dynamically with a split Hopkinson pressure bar system to measure both static and dynamic tensile strength of Barre granite. To understand the anisotropy in tensile strength, samples are cored and labelled using the three principle directions of Barre granite to form six sample groups. For dynamic tests, a pulse shaping technique is used to achieve dynamic equilibrium in the samples during the dynamic test. The finite element method is then implemented to formulate equations that relate the failure load to the material tensile strength by employing an orthotropic elastic material model. For samples in the same orientation group, the tensile strength shows clear loading rate dependence. The tensile strengths also exhibit clear anisotropy under static loading while the anisotropy diminishes as the loading rate increases, which may be due to the interaction of pre-existing microcracks.     

利用水合硅酸钠钙渣回收碱并用于制备硅灰石纳米粉体的实验研究

从高硅含铝原料霓辉正长岩中提取氧化铝时,硅以水合硅酸钠钙的形式排出。实验研究了水合硅酸钠钙渣的高效利用技术。利用水合硅酸钠钙自身的水解作用和在NaOH溶液中使之分解两种方法来回收其中的Na2O,所得NaOH溶液经蒸发浓缩后可循环利用。回收碱后剩余的固体渣用来制备硅灰石粉体。实验得出回收碱的优化条件为温度180 ℃,起始溶液的Na2O浓度为20 g/L,液固比为4∶1,洗涤6~7次。在此条件下,碱回收率可达90%以上。对回收碱后所得固体渣进行差热-热重分析,确定制备硅灰石粉体的煅烧温度。在820 ℃下煅烧2 h,制得颗粒尺寸为50~100 nm的α-CaSiO3纳米粉体,对其反应机理进行了初步的探讨。     

�������������ֽ�ؿǴ�ֱ�α����������Σ���Է���

??????????????????????????????????????????????????????????????????????????????????????????????????????Σ??????????Σ?????????????????????????ε????????????????У????? ?????????????????????????? ???α???????????????????????????????????????????о??????????????????????????????????????????????????????????????????????????26 mm/a???????α?????????????????????Щ??????????α????????????(??????)??????α?????仯???2008???????????????????????????????????????п??????????????????     

应用最小二乘法辨识SS-Y型伸缩仪的传递函数

给定SS-Y型伸缩仪系统阶跃信号输入,分别记录该系统的输入输出数据,得到系统的输入输出对.应用最小二乘法辨识出该系统的传递函数,并通过Matlab仿真验证了该系统传递函数模型的有效性.     

近40 年山西省初终霜日的变化特征

利用山西省境内分布较为均匀的52 个地面气象站1970-2009 年的霜日观测资料,采用线性倾向估计法、累积滤波器法结合非参数统计检验方法分析了初终霜日的基本特征及其变化趋势;利用M-K法分析了霜日的突变特征。结果表明：初霜日、终霜日的出现以及无霜期的长短与地理因素密切相关,随着纬度逐渐偏北、海拔逐渐升高,初霜日提前、终霜日推后、无霜期缩短。从全省平均情况看,初霜日呈现显著的推后趋势,无霜期呈现显著的延长趋势,而终霜日的变化则以波动为主,线性变化趋势不显著。从突变检测情况看,初霜日、终霜日和无霜期在40 年间均存在一次明显突变,初霜日的突变点出现在2000 年,终霜日和无霜期的突变点出现在1997 年。从变化趋势的空间分布看,初霜日显著推后的区域大片集中在晋中东部、吕梁北部和忻州西部,以及分散在运城南部、临汾西北部和大同南部。终霜日显著提前的区域位于晋中东部山区、吕梁山东部和忻州西部。无霜期显著延长的区域位于西北部黄河沿岸、省境中东部和运城南段。变化趋势为初霜日提前、终霜日推后和无霜期缩短的区域未通过显著性检验。     

矿区植被物化参数高光谱遥感估算研究

基于高光谱遥感数据Hyperion和植物冠层反射光谱,应用指数法、回归统计法和基于光谱位置变量的方法对矿区植被生物量和叶绿素浓度(SPAD)进行估算.结果表明:植被指数R752/R548与植物鲜重相关性最高,相关系数为0.88;选用植物像元光谱,基于植被指数R752/R548,利用三次函数法构建植物鲜重估算模型精度较高,多重判定系数R2达0.883;植被指数DVI[752,640]与植物干重相关性最高,相关系数为0.42;基于植被指数DVI[752,640],应用线性回归法构建植被干重估算模型精度较低,多重判定系数R2为0.177;基于四点内插法提取的红边位置与叶绿素浓度显著相关,相关系数为0.433;Datt(1)和Datt(2)植被指数与叶绿素浓度存在显著相关,相关系数分别为0.871和0.868;基于红边位置(REP)、Datt(1)和Datt(2)植被指数构建植物叶绿素浓度估算模型精度较高,多重判定系数R2分别为0.814、0.805和0.781.应用高光谱遥感技术可有效地检测矿区受损生态环境下的植被,为矿区植物生态修复工程提供本底资料.     

最小数据方法在生态补偿中的应用——以甘南黄河水源补给区为例

甘南黄河水源补给区蓄水、补水功能对整个黄河流域水资源调节起了关键作用,亟需建立生态补偿机制保护生态环境。采用最小数据方法模拟出了草地水源涵养服务供给曲线,根据不同的生态恢复目标,确定补偿标准,估算新增水源涵养量。研究结果显示:(1) 通过生态补偿提高甘南黄河水源补给区水源涵养能力是可行的; (2)当合作、夏河、玛曲、碌曲、卓尼、临潭的补偿额分别达1 024.3、999.79、861.74、1 008.54、585.54、983.22元/hm²时,该区退化草地将全部禁牧,将新增水源涵养量2.253×10⁹m³;(3) 草地提供的水源涵养服务和农户经济行为存在空间异质性,因此应建立差别化、动态化补偿标准。     

动三轴试验固结时间对动剪切模量比和阻尼比影响的初步分析

动三轴试验是将试样在轴对称的三轴应力下进行固结,在不排水条件下进行的振动试验,同时可测定土样的动剪切模量比和阻尼比。土的动剪切模量比和阻尼比是土动力学特性的2个重要参数,在工程场地地震安全性评价工作和土层地震反应分析中不可缺少。为了减少工期,提高工效,及时而又准确地提交报告,我们结合自己多年的土工试验经验,对可塑状态以上的粘性土试样进行了缩短固结时间的对比试验,并得到理想的试验结果。