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921.
中华管鞭虾(Solenocera crassicornis)蛋白酶的纯化及其生化特性研究 总被引:1,自引:0,他引:1
采用Tris-HCl缓冲液(50mmol/L,pH7.5)抽提、Q-sepharose F.F.阴离子交换层析、Sephacryl S-300凝胶过滤层析、SDS-PAGE等方法,进行中华管鞭虾虾头蛋白酶的分离纯化、酶学性质及其动力学特性的研究。结果表明,中华管鞭虾虾头蛋白酶粗提物经层析后,得到聚丙烯酰胺凝胶电泳纯的一酶组分。该蛋白酶的比活力从359.39U/mg增加到8277.83U/mg,提高了23.03倍,回收率达37.69%,SDS-PAGE显示该蛋白酶只含一条谱带,相对分子量为24.50kDa。以偶氮酪蛋白作为底物,该酶的米氏常数Km值为0.28mg/ml,最适温度为55℃,最适pH为7.5;蛋白酶在60℃以下比较稳定,放置1h后活性仍保持在60%以上,而在60℃以上时蛋白酶活性急剧下降,80℃放置1h后,酶活性只残留21.32%。10mmol/L Cu2 、Zn2 和EDTA对该蛋白酶有较强的抑制作用,抑制率分别约为97%、96%和55%,10mmol/LMg2 能显著促进蛋白酶活性,而10mmol/LFe2 、Ba2 、Ca2 对蛋白酶活性的影响不大。推测中华管鞭虾蛋白酶可能为一种金属蛋白酶。 相似文献
922.
Multi-sensor core logger data and index properties were measured onboard the JOIDES resolution during ODP Leg 157 and compared with grain size distribution and carbonate contents measured in the on-shore laboratory. Cored sediments are similar in grain size, but very variable in carbonate content. Magnetic susceptibility clearly defines the volcanic turbidite layers, whereas GRAPE density and acoustic velocity help to define the coarser (silty) bases of some organic or calcareous turbidite layers. Index properties are mostly controlled by consolidation effects. 相似文献
923.
In this study, the correlation between simulated and measured radar velocity spectrum width(σv) is investigated. The results show that the dendrites growth zones(DGZs) and needles growth zones(NGZs) mostly contain dendrites(DN) and needles(NE), respectively.Clear σv zones(1.1 < σv(m s–1) < 1.3 and 0.3 < σv(m s–1) < 0.7 for the DGZ and NGZ, respectively) could be identified in the case studies(27 and 28 February 2016) n... 相似文献
924.
压汞法测定页岩孔隙特征的影响因素分析 总被引:2,自引:1,他引:1
压汞法是目前测定岩石内部孔隙特征的常用方法,但测试结果受样品尺寸、测量范围等多种因素的影响。本文以页岩为主要研究对象,采用压汞法等测试手段分析了不同的样品尺寸、接触角等条件下的孔隙特征。结果表明:1孔隙率与所选的孔径范围有关,在7.1 nm~100μm孔径范围内测量孔隙率的准确性更高;样品制备时可能产生人为裂隙导致孔隙率的测量误差较大。2在一定孔径范围内,与人工合成样品相比,页岩的平均孔径、孔隙率、比孔容等特征值受样品尺寸影响更大。页岩样品尺寸的减小,不仅能增加小孔隙间的连通性,而且可以降低较大裂隙的影响。3接触角从130°增加到150°,平均孔径变大约35%。因此应在准确测量接触角的情况下采用小尺寸样品进行测试,同时进一步完善并统一压汞法测量页岩孔隙特征的实验规范,以提高测试结果的准确性和可比性。 相似文献
925.
Effects of coarse-grained material on hydraulic properties and shear strength of top soil 总被引:2,自引:0,他引:2
Sidewalk failures associated with top soil of low shear strength are a common problem in urban areas. Mixing top soil with granite chips can be used to increase its permeability and shear strength. The effects of mixing granite chips with top soils on the hydraulic properties and shear strength under saturated and unsaturated conditions were investigated in this study. The results showed that the mixing top soils with granite chips caused changes in several key parameters of the soil–water characteristic curve (e.g., the air-entry value, the residual matric suction, and the residual volumetric water content) and the unsaturated permeability of the top soils. The saturated permeability and shear strength of the soil mixture increased with increasing content of granite chips. 相似文献
926.
927.
利用粉煤灰合成莫来石具有良好的工业发展前景,但由于普通粉煤灰中Al2O3含量较低使得合成莫来石时必须添加大量工业氧化铝,从而增加了合成成本.利用高铝粉煤灰直接制备M50莫来石以及高铝粉煤灰与少量工业氧化铝混合合成M60和M70莫来石,其物理性能可以达到我国<烧结莫来石>标准(YB/T5267-2005),这大大降低了合成成本.研究表明,用未处理过的高铝粉煤灰直接制备低牌号莫来石(M50)适宜的烧结温度为1400 ℃,用处理过的高铝粉煤灰或合成高牌号莫来石(M60、M70)适宜的烧结温度为1500 ℃;恒温时间对合成莫来石的影响远小于烧结温度,高温下缩短恒温时间比低温下延长恒温时间有利于莫来石的生成. 相似文献
928.
Comparison of dissolution under oxic acid drainage conditions for eight sedimentary and hydrothermal pyrite samples 总被引:1,自引:0,他引:1
Ran Liu Amy L. Wolfe David A. Dzombak Brian W. Stewart Rosemary C. Capo 《Environmental Geology》2008,56(1):171-182
The abiotic oxidative dissolution behaviors of eight natural pyrite samples, five sedimentary and three hydrothermal, from
various geological environments were compared under oxic conditions at pH 3 and 6 in a highly controlled batch reactor dissolution
system. The three sedimentary pyrite samples associated with coal had greater specific surface areas and also exhibited greater
apparent dissolution rates and extent than the other two sedimentary and three hydrothermal samples under both pH conditions.
However, after normalizing for surface area, the dissolution rate constants for the different pyrite samples were similar;
the greatest difference was between the two non-coal sedimentary pyrite samples. Pyrite morphology and the presence of trace
metals could contribute to the differences in dissolution behavior as reflected in the normalized dissolution rates. The sulfur:iron
ratio observed in the aqueous solution at pH 3 increased with time, but was always less than 2.0 (predicted from the stoichiometry
of dissolution) for all the pyrite samples during the 24-h experimental duration. This can be explained by the disproportionation
dissociation of thiosulfate, an initial product of pyrite dissolution, to elemental sulfur and sulfate which does not occur
in a 1:1 ratio. The results of this work indicate the importance of extracting and using the specific pyrite(s) relevant to
particular mining areas in order to understand pyrite dissolution rates and the influence of environmental conditions on those
rates. 相似文献
929.
930.
This work presents geochemical characterization of isolated kerogen out of clay fraction using petrography studies, infrared absorption and solid state 13C nuclear magnetic resonance (NMR) spectroscopy, with N‐alkane distributions of saturated hydrocarbon. Mineralogical study of clay mineral associations was carried out using X‐ray diffraction (XRD), on Ypresian phosphatic series from Gafsa‐Metlaoui basin, Tunisia. The XRD data indicate that smectite, palygorskite and sepiolite are the prevalent clay minerals in the selected samples. In this clay mineral association, the N‐alkane (m/z = 57) distribution indicates that the marine organic matter is plankton and bacterial in origin. The kerogens observed on transmitted light microscopy, however, appear to be totally amorphous organic matter, without any appearance of biological form. The orange gel‐like amorphous organic matter with distinct edges and homogenous texture is consistent with a high degree of aliphaticity. This material has relatively intense CH2 and CH3 infrared bands in 13C NMR peaks. This aliphatic character is related to bacterial origin. Brown amorphous organic matter with diffuse edges has a lower aliphatic character than the previous kerogen, deduced from relatively low CH2 and CH3 infrared and 13C NMR band intensities. 相似文献