合浦珠母贝基质蛋白KRMP-3对二价金属离子选择性的研究   总被引：1，自引：0，他引：1  

吴晨  苏境坦  梁健  梁晓  谢莉萍  张荣庆 《海洋科学》2013,37(4):26-31

用大肠杆菌表达含有GST标签的基质蛋白KRMP-3。利用圆二色谱(Circular Dichroism, CD)研究不同浓度钙离子和镁离子对基质蛋白 KRMP-3二级结构的影响。结果表明,钙离子对其二级结构的变化远大于镁离子;同时,采用荧光淬灭法研究 KRMP-3对钙,镁,锶,钡等二价金属离子的选择性,结果表明, KRMP-3对钙离子有特异性选择性,钙离子与KRMP-3的结合常数K约为103 L/mol,结合位点数 n 近似为1,表明 KRMP-3与钙离子的结合能力适中,推测基质蛋白 KRMP-3对合浦珠母贝( Pinctada fucata)棱柱层形成起到促进作用。  相似文献   

Implementation schemes for avoiding artifact discontinuities in simulated annealing   总被引：3，自引：0，他引：3  

Steven F. Carle 《Mathematical Geology》1997,29(2):231-244

The simulated annealing algorithm has been applied successfully to conditional simulation of categorical variables (e.g., rock or facies units) with the objective of improving the match between measured and modeled spatial variability. In some implementation schemes, however, spurious features termed “artifact discontinuities” may occur near conditioning data, especially during the “zero- temperature” case referred to as simulated quenching. This paper shows that artifact discontinuities can be avoided by considering the anisotropy of the spatial variability model, reducing the number of lag vectors used in the objective function, and providing a rudimentary initial configuration. Results from several test cases suggest that the artifact discontinuities might be caused by overly precise fitting of measured to modeled spatial variability.  相似文献   

Observations concerning the nature of maceral fluorescence alteration with time     

Alan Davis  R.F. Rathbone  Rui Lin  J.C. Quick 《Organic Geochemistry》1990,16(4-6)

Distinctive features of the alteration of maceral fluorescence intensity with upon blue-light or UV excitation are related to the level of organic maturation. Alteration has been measured in different media; the results demonstrate clearly that the negative component of the alteration phenomenon is due to photochemical oxidation. Highly weathered bituminous coals do not display negative alteration because the potential for oxidation quenching has been reduced. The positive component of alteration is thought to be due to the creation of additional absorption centers and increased molecular rigidity as a result of photochemical oxidation and the enhancement of cross-linking among mobile phase and network molecules.  相似文献   

Determination of Hg and MeHg complexation with dissolved organic matter by fluorescence quenching titration     

Pingqing FU Fengchang WU Feiyue WANG 《中国地球化学学报》2006,25(B08):264-265

In natural waters inorganic mercury （Hg） and methylmercury （MeHg） are complexed with a variety of inorganic and organic ligands, such as OH^-, Cl^-, sulfide, thiols, and dissolved organic matter （DOM）. The bioavailability and toxicity of Hg and MeHg are related to their speciation, instead of their total concentrations. Among these species, Hg-DOM and MeHg-DOM complexes are the least known, due to the complexity and site-specificity of DOM in natural waters. Here we report the complexation between DOM and Hg or MeHg using fluorescence spectroscopy. The Suwannee River fulvic acid, peat humic acid, amino acid typotophan, and natural organic matter from the Suwannee River, Nordic River, and Delta Marsh were studied at their respective excitation/emission maxima,  相似文献   

基于荧光猝灭原理的溶解氧分析仪的研制及其应用     

李文龙  荆淼  王征  王小如 《海洋科学进展》2007,25(3):355-361

研制出一种对溶解氧敏感的传感膜,其荧光材料主要是邻菲咯啉钌。由光源发出的中心波长为465 nm的强光照射到铺有该络合物的膜片上,激发出中心波长为620 nm的荧光,水体中的溶解氧会对激发出的荧光产生猝灭效应,猝灭程度与溶解氧的质量浓度之间存在线性关系。该膜片在无氧水中的荧光强度是空气饱和水中的20倍,变化较为明显。对比检测荧光信号在待测水体中猝灭前后的强度,即可测出水体中溶解氧的质量浓度。基于这一原理和荧光测量技术研制了光学溶解氧分析仪,利用该仪器对6处不同水域的天然水体进行测试,所得测试结果与国标碘量法的测试结果之间不存在显著性差异,误差≤2%,响应时间<1 min。在海水中30 m深处进行36h稳定性考察,所得溶解氧质量浓度数值平均偏差小于0.2 mg.L-1,证实仪器可适应较为恶劣的环境,且稳定性较好。  相似文献   

钻机转盘用大型推力轴承淬火工艺分析及改进          下载免费PDF全文

关蜀军 《探矿工程》2000,(6):43-44

工程钻机及水井钻机转盘用大型推力轴承的加工比较困难,存在淬火变形问题,分析了轴承圈的淬火工艺及淬火变形产生的主要原因,通过设计心用简易淬火压床,改进淬火工艺,减小了轴承圈的变形,提高了制造质量。  相似文献   

RETRACTED ARTICLE: Quorum-sensing of bacteria and its application     

Guoliang Jiang  Mingxia Su 《中国海洋大学学报(英文版)》2009,8(4):385-391

Quorum sensing, or auto induction, as a cell density dependent signaling mechanism in many microorganisms, is triggered via auto inducers which passively diffuse across the bacterial envelope and therefore intracellulaly accumulate only at higher bacterial densities to regulate specialized processes such as genetic competence, bioluminescence, virulence and sporulation. N-acyl homoserine lactones are the most common type of signal molecules. Aquaculture is one of the fastest-growing food-producing industries, but disease outbreaks caused by pathogenic bacteria are a significant constraint on the development of the sector worldwide. Many of these pathogens have been found to be controlled by their quorum sensing systems. As there is relevance between the pathogenic bacteria’s virulence factor expression and their auto inducers, quorum quenching is a new effective anti-infective strategy to control infections caused by bacterial pathogens in aquaculture. The techniques used to do this mainly include the following: (1) the inhibition of signal molecule biosynthesis, (2) blocking signal transduction, and (3) chemical inactivation and biodegradation of signal molecules. To provide a basis for finding alternative means of controlling aquatic diseases by quorum quenching instead of treatment by antibiotics and disinfectants, we will discuss the examination, purification and identification of auto inducers in this paper.  相似文献   

荧光熄灭法测定煤矸石中微量锌   总被引：7，自引：0，他引：7  

罗道成  易平贵等 《岩矿测试》2002,21(1):76-78

在pH8.6的Na2B4O7-HCl缓冲介质中，基于微量Zn^2 对5－溴水杨基荧光酮体系的荧光熄灭效应，建立了测定微量Zn^2 的荧光分析方法。结果表明，当激发波长λex=365nm，荧光发射波长λem=538nm时，Zn^2 量在0.0-400.0μg/L内与体系的荧光熄灭程度呈线性关系，方法的检出限为0.38μg/L。方法用于煤矸石中微量Zn^2 的测定，结果与极谱法结果一致，6次测定的RSD＜3．0％。  相似文献   

Mean Field Dynamos with Algebraic and Dynamic α-Quenchings     

Tworkowski  A.  Covas  E.  Tavakol  R.  Brandenburg  A. 《Studia Geophysica et Geodaetica》1998,42(3):350-355

Calculations for mean field dynamo models (in both full spheres and spherical shells), with both algebraic and dynamic -quenchings, show qualitative as well as quantitative differences and similarities in the dynamical behaviour of these models. We summarise and enhance recent results with extra examples. Overall, the effect of using a dynamic appears to be complicated and is affected by the region of parameter space examined.  相似文献   

Ultraviolet absorbance titration for the determination of conditional stability constants of Hg（Ⅱ） and dissolved organic matter   总被引：1，自引：0，他引：1  

BAI Yingchen WU Fengchang WAN Guojing LIU Congqiang FU Pingqing LI Wen 《中国地球化学学报》2008,27(1):46-52

Strong interaction between natural dissolved organic matter （DOM） and Hg（Ⅱ） may influence the transport, conversion, toxicity and bio-validity of mercury in the environment. In this paper ultraviolet （UV） absorbance titration was employed for the first time for the determination of the conditional stability constants of Hg（Ⅱ） and （DOM）. With increasing Hg（Ⅱ） concentrations, the UV absorbance of fulvic acid, humic acid, and DOM in river increases progressively. By linear and non-linear model fitting, the conditional stability constants （lgK） of Hg（Ⅱ） and DOM were worked out to be 3.54-4.93 and 3.64-4.85, respectively. The results are consistent with those acquired by the typical fluorescence quenching titration method, with the maximum relative error of lgK being 2.6% and the average relative error being 0.2%. The UV absorbance titration method has the advantages of rapid determination, simple performance, and it will probably become a new approach to studying interactions between DOM and trace metallic ions.  相似文献