Major and trace element characterization of tephra layers offshore Pantelleria Island: insights into the last 200 ka of volcanic activity and contribution to the Mediterranean tephrochronology

A detailed tephrochronological study was carried out on the deep‐sea core collected from Site 963A in the Sicily Channel during ODP Leg 160. The chronology of the succession is provided by an age–depth model based on isotope stratigraphy and quantitative eco‐biostratigraphy. Major, trace and rare earth element content was obtained on single glass grains through electron probe micro‐analysis and laser ablation–inductively coupled plasma mass spectrometry techniques from six well‐preserved tephra layers, characterized by a discrete thickness found along the succession. These deposits were correlated with the volcanic activity of Pantelleria and dated at 42.5, 127.5, 128.1, 129.1, 188.7 and 197.7 ka. This detailed chemical characterization of the studied deposits aims to provide a valuable reference database for scientists working on both proximal and distal products erupted at Pantelleria island during the Late Pleistocene. This study, moreover, offers the opportunity to better identify Pantelleria‐related marker tephras within the tephrochronological framework of the central and eastern Mediterranean area. Copyright © 2012 John Wiley & Sons, Ltd.     

水分子对硝酸根分子振动的影响

利用第一性原理计算硝酸根与1～3个水分子形成的水合物(NO3-.nH2O,n=1～3)的红外吸收谱,并与测量的硝酸钠水溶液的红外吸收谱进行了比较分析。计算结果表明硝酸根与水分子所形成的水合物具有多种稳定的结构,其中硝酸根与1个水分子结合的亚稳定结构,其硝酸根反对称伸缩振动的劈裂与硝酸钠水溶液中硝酸根的红外吸收谱结果一致,表明硝酸盐溶液中每一硝酸根与附近水分子的作用效果等效为NO3-.1H2O。     

Radiation-induced decomposition of U(VI) phases to nanocrystals of UO2

U⁶⁺-phases are common alteration products, under oxidizing conditions, of uraninite and the UO₂ in spent nuclear fuel. These U⁶⁺-phases are subjected to a radiation field caused by the α-decay of U, or in the case of spent nuclear fuel, incorporated actinides, such as ²³⁹Pu and ²³⁷Np. In order to evaluate the effects of α-decay events on the stability of the U⁶⁺-phases, we report, for the first time, the results of ion beam irradiations (1.0 MeV Kr²⁺) of U⁶⁺-phases. The heavy-particle irradiations are used to simulate the ballistic interactions of the recoil-nucleus of an α-decay event with the surrounding structure. The Kr²⁺-irradiation decomposed the U⁶⁺-phases to UO₂ nanocrystals at doses as low as 0.006 displacements per atom (dpa). U⁶⁺-phases accumulate substantial radiation doses (∼1.0 displacement per atom) within 100,000 yr if the concentration of incorporated ²³⁹Pu is as high as 1 wt.%. Similar nanocrystals of UO₂ were observed in samples from the natural fission reactors at Oklo, Gabon. Multiple cycles of radiation-induced decomposition to UO₂ followed by alteration to U⁶⁺-phases provide a mechanism for the remobilization of incorporated radionuclides.     

海藻生物吸附金属离子的机理和影响因素

本文在前文“海藻生物吸附金属离子技术的特点和功能”的基础上，进一步阐述了生物吸附的机理，影响生物吸附的因子，生物吸附剂的洗脱及固定化等问题．通过对这些工作的了解，使我们对正在发展的海藻生物吸附技术理论基础和实际应用研究有更确切的认识、这些理论基础研究工作正是为对该项技术发展的进一步研究打下实际应用基础。     

Characteristics and quantitative of negative ion in salt aqueous solution by Raman spectroscopy at -170℃

The results from Raman spectroscopy analysis of salt aqueous solutions at -170℃ demonstrate that for those clearly sharp iron peaks whose Raman wavenumber is close to each other such as and , their original shape could be restorable by the stripping technique, and that ice's sharp characteristic peak (3090-3109 cm-1) is steady, while the spectrum band of the complex compound (nCl--[H+-OH-]n) chlorine ion combined chemically with water molecule is 3401-3413 cm-1. On the other hand, the research shows that the higher the negative iron concentration, the stronger its Raman characteristic peak intensity and the smaller the ice's. Based on the number of data and theoretical work, the strong correlation of the molar concentration of negative ion with the band area ratio is built up. Moreover, the developed Raman method is successfully used in the component analysis of the field fluid inclusions from Silurian sandstone in Tarim basin.     

One‐Pot Synthesis of Xanthate‐Functionalized Cellulose for the Detection of Micromolar Copper(II) and Nickel(II) Ions

A one‐pot synthesis and application of cellulose‐based sensors to efficiently detect various toxic metal ions in aqueous solutions in micromolar quantities is reported. Cellulose microfibers have been functionalized with carbon disulfide in alkaline solution to form cellulose xanthate. The material detects several toxic metal ions such as copper, nickel, or cobalt ions through color change detectable by the naked eye. The optical sensor can be used as an ideal flash test for assessing the quality of drinking water.     

基于城市抗震弹塑性分析的我国主要城市建筑地震风险评估

全国尺度的城市建筑地震风险评估对城市防震减灾工作有着重要意义。本文根据全国人口普查和城市统计年鉴等给出的宏观指标建立城市建筑数据库,通过GEAR1方法(Global earthquake activity rate model 1)和第五代中国地震动参数区划图给出具体场地的地面运动强度,通过地面坡度与剪切波速的对应关系确定的场地类别来考虑地震动输入,采用城市抗震弹塑性分析方法建立建筑分析模型,通过地震经济损失风险指标和建筑严重破坏和倒塌风险作为风险评价指标,给出中国大陆主要城市建筑地震风险分布图。结果分析表明,本文方法可以基于可公开获取的数据预测全国不同城市的建筑震害风险;根据第五代地震动参数区划图给出的地面强度,地震经济损失高风险区主要是设防加速度0.3g以上地区;考虑城市人口、GDP因素后,中、东部城市因人口和财富密度较高,建筑地震风险增加明显;不同地震动选波对经济损失风险影响较小,而对倒塌风险影响较大。本文分析方法可以为城市建筑地震风险分析提供相关参考。     

Major and trace element studies on garnets from Palaeozoic kimberlite-borne mantle xenoliths and megacrysts from the North China craton

Palaeozoic kimberlites from Mengyin, Shandong and Fuxian, Liaoning, eastern China, contain plenty of mantle xenoliths (peridotites, eclogites) and megacrystic minerals. In-situ electron and ion microprobe analyses on garnets from these xenoliths and megacrysts as well as relevant theoretical modeling reveal that these garnets were more or less affected by kimberlitic silicate melts prior to the encapsulation, in which eclogitic garnet from Fuxian, Liaoning Province, was little affected by mantle metasomatism, representing the primitive depleted mantle composition. In contrast, garnet from Mengyin, Shandong Province, and all megacrystic garnets were completely modified by metasomatic melts/fluids and reached perfectly chemical equilibrium, thus reflecting the characteristics of the enriched mantle. It is inferred that old lithospheric mantle beneath the North China craton was fairly strongly modified by metasomatism before Palaeozoic kimberlite emplacement.     

Characteristics and quantitative of negative ion in salt aqueous solution by Raman spectroscopy at ?170°C

The results from Raman spectroscopy analysis of salt aqueous solutions at −170°C demonstrate that for those clearly sharp iron peaks whose Raman wavenumber is close to each other such as NO ₃ ⁻ and CO ₃ ²⁻ , their original shape could be restorable by the stripping technique, and that ice’s sharp characteristic peak 3090–3109 cm⁻¹) is steady, while the spectrum band of the complex compound (nCl⁻-[H⁺-OH⁻]_n) chlorine ion combined chemically with water molecule is 3401–3413 cm⁻¹. On the other hand, the research shows that the higher the negative iron concentration, the stronger its Raman characteristic peak intensity and the smaller the ice’s. Based on the number of data and theoretical work, the strong correlation of the molar concentration of negative ion with the S _i/S _{H 2}O band area ratio is built up. Moreover, the developed Raman method is successfully used in the component analysis of the field fluid inclusions from Silurian sandstone in Tarim basin.     

多尺度CT成像技术识别超低渗透砂岩储层纳米级孔喉

以鄂尔多斯盆地X地区长6储层为研究对象,利用多尺度CT成像技术、聚焦离子束扫描电镜技术,结合Avizo软件的强大数据处理和数值模拟功能,对研究区目的层岩石样品进行不同尺度孔喉分维数重构,建立三维超低渗透砂岩储层纳米级孔隙结构模型.研究表明,微米尺度下,超低渗透砂岩储层孔喉形态呈点状、球状和条带状及管状.储集空间类型以溶蚀微孔为主且多孤立分布,局部孔隙为片状,连通性较差.纳米尺度下,超低渗透砂岩储层孔喉系统整体较发育,孔喉形态呈球状、短管状.远离裂隙处多为孤立状,连通性较差,仅具有储集能力.微裂缝、粒间缝发育部位多为短管状,有一定连通性,相当于喉道.微观非均质性较强,岩样整体较致密,局部相互连通,溶蚀孔及裂隙对储集能力、渗滤能力具有控制作用.数值计算求得目的层A、Y、C三个样品的孔隙度分别为6.95%、5.55%、4.44%,渗透率分别为0.828×10^-3μm²、0.115×10^-3μm²、0.00065×10^-3μm².聚焦离子束扫描电镜与多尺度CT成像...