西沙珊瑚鍶溫度計: 便捷高精度海洋古水溫代用指標

Strontium concentrations in modem Porites coral from XishaIslands were determined by precise thermal ionization mass spectrometry. The coral skeleton grew in the period from 1976 to 1994. The results indicate that the variability of coral Sr is periodically at annual cycles, and is in agreement with in situ measured sea surface temperature (SST). The calibration of Sr and SST with correlation coefficient r = -0. 94 has been developed at monthly sampling resolution. In addition, maximum and minimum seasonal monthly Sr and SST values were also regressed for the 18-year interval, and the correlation coefficient is -0. 98. The error of this Sr thermometer is better than 0. 5 ℃.西沙群島現代濱珊瑚1976～1994年生長期間Sr含量的高精度熱電離質譜測定結果表明，Sr含量隨季節發生周期性的變化，并與當地同期實測海水月平均溫度變化相吻合，其Sr含量與實測海水溫度相關系數為-0.94。這18年冬夏季極端Sr含量與同期月溫的相關系數可高達-0.98。Sr溫度計誤差小于0.5℃。published_or_final_versio

南海北部珊瑚Ba/Ca比值的季节变化及其环境意义

利用等离子体质谱技术分析了取自海南岛南部沿岸的现代滨珊瑚高分辨率的Ba／Ca比值。结果表明，该珊瑚的Ba／Ca比值具有明显的双峰态的季节变化，其中春季和秋季Ba／Ca比值较高，而冬、夏两季则较低。海南岛南部及邻近地区季节降雨的变化所控制的陆源Ba输入是这些珊瑚Ba／Ca比值变化的重要控制因素，而该区夏季相对较高的表层海水生产力可能也对其有重要影响。High-resolution Ba/Ca ratios of a modern Porites coral from Sanya Bay, offshore of Hainan Island, were measured by ICP-MS. The results exhibit seasonal periodical ventilation of the coralline Ba/Ca ratios with higher Ba/ca ratios in spring and autumn and lower in winter and summer. variation of the terrestrial Ba flux to this area,which was controlled by seasonal precipitation of Southern Hainan Island and surmunded areas, is the key role to these Ba/Ca patterns. On the other hand, the relatively high surface productivity of the area in summer may contribute to the lower Ba/Ca ratios of the coral.postprin

Preliminary study on TIMS U-Th dating technique and their application

Thermal ionization mass spectrometry (TIMS) U-Th technique in dating purecarbonate has been established in our laboratory and was used to determine the ages of the Holocene coral samples from the South China Sea and a National Reference Material of uranium-series, GBW04413. The TIMS results of GBW04413 are in good agreement with their reference data determined from α-couning, indication that the ages by TIMS U-Th method are reliable. The TIMS ages of the coral samples older than 5ka have slightly older TIMS U-Th ages than their [14] C ages, which agrees with previous studies [12, 13, 16].尝试了用热电离质谱方法测定南海第四纪珊瑚的U- Th 年龄, 并利用国家铀系年龄标准物质GBW04413 来监测分析结果的合理性。结果显示, GBW04413 的TIMS 年龄与作为推荐值的A记数方法测定结果一致, 反映出其可靠性; 而年龄在1ka 左右的珊瑚样品的TIMS 年龄与14C 年龄一致, >5ka 样品的TIMS 年龄老于14C 年龄, 体现两种方法的系统差别。published_or_final_versio

Coralline Sr/Ca and Mg/Ca thermometer for the northern South China Sea: calibration and primary application high resolution on high-resolution SST reconstructing

利用全谱直读等离子体光谱(ICP2AES) 的分析方法精确分析了南海珊瑚的SrPCa 和MgPCa 比值,结合实测表层海水温度(SST),标定了海南岛南部三亚海域和西沙海域两个滨珊瑚的SrPCa 和MgPCa 温度计。在此基础上,尝试对两个南海北部全新世时期的珊瑚进行SST记录重建。结果显示约540aB.P. (小冰期) 西沙海域夏季月均SST 较现代低约1℃,而约6 500aB.P. (大暖期) 海南岛三亚海域夏季月均SST则高出现代1.0～1.5℃。The method for precisely and simultaneously measuring the coralline Sr/Ca and Mg/Ca ratios was established using inductively coupled plasma atomic emission spectrometry (ICP-AES). Using this method, the high-resolution Sr/Ca and Mg/Ca ratios of two Porites lutea from Sanya, South Hainan Island and Xisha Islands were measured. By comparing to the instrumentally measured sea surface temperatures in these two areas, the coralline Sr/Ca thermometer and the Mg/Ca thermometer were calibrated. These two thermometers can provide SST records with an error bar < 0.2℃, and they are suitable for high-resolution SST reconstructions in these areas. Based on these two thermometers, two short SST records were reconstructed from two Holocene Porites corals of the northern South China Sea. The results indicated that the monthly summer SSTs in Xisha Islands at about 540 years ago (the Little Ice Age) were 1℃ lower than that at present, and the monthly summer SSTs in Sanya, southern Hainan Island at 6 500 years ago (the Megathermal) were about 1℃ to 1 5℃ higher than that at present.published_or_final_versio

Magnetic field effects on the electroluminescence of organic light emitting devices: A tool to indicate the carrier mobility

The magnetoelectroluminescence (MEL) of organic light emitting devices with a N, N′ -bis(l-naphthyl)- N, N′ -diphenyl- 1, l′ -biphentl- 4, 4′ -diamine:tris-(8-hydroxyquinoline) aluminum (NPB: Alq 3) mixed emission layer (EML) has been investigated. We find that MEL is maximized when the volume ratio of NPB of the mixed EML reaches 30% and the EML thickness is 40 nm. The features of MEL under various magnetic field strengths are insensitive to the change in EML thickness and mixing ratio. Meanwhile, MEL has a close relationship with the carrier mobility. We have conducted a theoretical study to further verify the relationship. Our experimental and theoretical results confirm that MEL can function as a tool to indicate the mobility. © 2010 American Institute of Physics.published_or_final_versio

Investigation of the behaviour of electronic resistive switching memory based on MoSe<font size=-1>₂</font>-doped ultralong Se microwires

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Quasi-Normal Modes of Stars and Black Holes

Perturbations of stars and black holes have been one of the main topics of relativistic astrophysics for the last few decades. They are of particular importance today, because of their relevance to gravitational wave astronomy. In this review we present the theory of quasi-normal modes of compact objects from both the mathematical and astrophysical points of view. The discussion includes perturbations of black holes (Schwarzschild, Reissner-Nordstr\"om, Kerr and Kerr-Newman) and relativistic stars (non-rotating and slowly-rotating). The properties of the various families of quasi-normal modes are described, and numerical techniques for calculating quasi-normal modes reviewed. The successes, as well as the limits, of perturbation theory are presented, and its role in the emerging era of numerical relativity and supercomputers is discussed.Comment: 74 pages, 7 figures, Review article for "Living Reviews in Relativity

Cytokines and growth factors cross-link heparan sulfate

The glycosaminoglycan heparan sulfate (HS), present at the surface of most cells and ubiquitous in extracellular matrix, binds many soluble extracellular signalling molecules such as chemokines and growth factors, and regulates their transport and effector functions. It is, however, unknown whether upon binding HS these proteins can affect the long-range structure of HS. To test this idea, we interrogated a supramolecular model system, in which HS chains grafted to streptavidin-functionalized oligoethylene glycol monolayers or supported lipid bilayers mimic the HS-rich pericellular or extracellular matrix, with the biophysical techniques quartz crystal microbalance (QCM-D) and fluorescence recovery after photobleaching (FRAP). We were able to control and characterize the supramolecular presentation of HS chains—their local density, orientation, conformation and lateral mobility—and their interaction with proteins. The chemokine CXCL12α (or SDF-1α) rigidified the HS film, and this effect was due to protein-mediated cross-linking of HS chains. Complementary measurements with CXCL12α mutants and the CXCL12γ isoform provided insight into the molecular mechanism underlying cross-linking. Fibroblast growth factor 2 (FGF-2), which has three HS binding sites, was also found to cross-link HS, but FGF-9, which has just one binding site, did not. Based on these data, we propose that the ability to cross-link HS is a generic feature of many cytokines and growth factors, which depends on the architecture of their HS binding sites. The ability to change matrix organization and physico-chemical properties (e.g. permeability and rigidification) implies that the functions of cytokines and growth factors may not simply be confined to the activation of cognate cellular receptors

Fifteen new risk loci for coronary artery disease highlight arterial-wall-specific mechanisms

Coronary artery disease (CAD) is a leading cause of morbidity and mortality worldwide. Although 58 genomic regions have been associated with CAD thus far, most of the heritability is unexplained, indicating that additional susceptibility loci await identification. An efficient discovery strategy may be larger-scale evaluation of promising associations suggested by genome-wide association studies (GWAS). Hence, we genotyped 56,309 participants using a targeted gene array derived from earlier GWAS results and performed meta-analysis of results with 194,427 participants previously genotyped, totaling 88,192 CAD cases and 162,544 controls. We identified 25 new SNP-CAD associations (P &lt; 5 × 10(-8), in fixed-effects meta-analysis) from 15 genomic regions, including SNPs in or near genes involved in cellular adhesion, leukocyte migration and atherosclerosis (PECAM1, rs1867624), coagulation and inflammation (PROCR, rs867186 (p.Ser219Gly)) and vascular smooth muscle cell differentiation (LMOD1, rs2820315). Correlation of these regions with cell-type-specific gene expression and plasma protein levels sheds light on potential disease mechanisms

Folate polyglutamylation is required for rice seed development

In plants, polyglutamylated folate forms account for a significant proportion of the total folate pool. Polyglutamylated folate forms are produced by the enzyme folylpolyglutamate synthetase (FPGS). The FPGS enzyme is encoded by two genes in rice, Os03g02030 and Os10g35940. Os03g02030 represents the major expressed form in developing seed. To determine the function of this FPGS gene in rice, a T-DNA knockout line was characterised. Disrupting Os03g02030 gene expression resulted in delayed seed filling. LC-MS/MS-based metabolite profiling revealed that the abundance of mono- and polyglutamylated folate forms was significantly decreased in seeds of the knockout line. RT-qPCR detected an increase in the transcript abundance of folate biosynthesis genes in seed of the knockout plant, whereas the folate deglutamating enzyme ?-glutamyl hydrolase mRNA level was reduced. Our study has uncovered a novel role for folate polyglutamylation during rice seed development and a potential feedback mechanism to maintain folate abundance.(Résumé d'auteur