青藏高原多年冻土区高寒草甸植物群落主要植物化学元素含量特征

分析了青藏高原北麓河地区29种高寒植物15个元素含量的特征。结果表明,这些植物中元素平均含量>400μg/g的元素有Ca,Mg,Na,K,Fe,10～100μg/g的有Mn,Cr,Zn,Cu,<10μg/g的有Ni,Co,As,Pb,Cd,Hg;种间同种元素的含量变化规律不统一。相关性分析表明,Cu与Cd,Fe与Cd和Hg,Cr与Ni,Co和Mg极显著正相关,Cr和Ca极显著负相关;聚类分析表明,Na,As元素对本区植物聚类的影响最大,莎草科、禾本科、菊科科内植物元素含量相似。     

基于单颗粒黑碳光度计(SP2)方法的青藏高原冰芯黑碳记录研究

青藏高原冰川蕴含了丰富的历史环境变化信息。通过青藏高原冰芯钻取及环境指标分析,可在季节至万年时间尺度上重建高分辨率环境变化历史。黑碳气溶胶来源于生物和化石燃料燃烧排放,对光具有强烈的吸收作用,是气候环境变化的敏感因子之一。准确测量冰芯中的黑碳粒子浓度,是恢复其排放历史、评估其气候环境效应的必要手段。单颗粒黑碳光度计(Single Particle Soot Photometer, SP2)是近些年发展起来的用于雪冰样品中黑碳测量的主要方法之一,能够获得准确的黑碳浓度信息。近10年来,实验室开展了大量的冰芯黑碳样品测量,从野外冰芯钻取、样品前处理、仪器原理及测试、黑碳数据处理等全过程对SP2在青藏高原冰芯黑碳研究中的应用与问题进行了全面系统的阐述。同时,将SP2与热光学(Thermal-optical method)等测试方法进行对比,强调了SP2对冰芯黑碳样品研究的可靠性,并对未来黑碳研究的进一步发展作出了展望。     

Theoretical Study of the Thermal Decomposition of Chlorofluoromethanol (CHClFOH)

Introduction Hydrochlorofluorocarbons (HCFCs) have been widely used as replacements of chlorofluorcarbons (CFCs). The insertion of O (1D) into the CH bond of HCFC forms the activated alcohol. It has been shown that these hot alcohols play an important role in the degradation mechanism of atmospheric compounds1.Chlorofluoromethanol (CHClFOH) appears in the reaction of O (1D) with CH2ClF (HCFC-31)2. Neither experimental nor theoretical study of this species was available to date. U…     

涡旋提取-电感耦合等离子体发射光谱(ICP-OES)法测定酸性和中性土壤中交换性盐基总量

传统的土壤交换性盐基总量检测方法前处理过程复杂,检测时间长,建立涡旋提取-电感耦合等离子体发射光谱(ICP-OES)法,大大提高了检测效率。采用涡旋提取中性和酸性土壤中交换性盐基总量,结合电感耦合等离子发射光谱仪（ICP-OES）同时测定土壤提取液中交换性盐基总量钙镁钠钾含量。通过考察土液比,涡旋时间,涡旋转速以及方法的精密度和准确度。结果表明,最佳涡旋条件为土液比为1:50,涡旋时间为20 min,涡旋速度为1500 r/min。利用ICP-OES测定国家标准物质RMH-A275、RMH-A274和GBW07458a（ ASA-7a）土壤提取液中交换性盐基总量钙镁钠钾含量,各元素测定结果均在标准值范围内,相对标准偏差均小于2 %,交换性钙镁钠钾的方法检出限分别为0.048 cmol/kg、0.035 cmol/kg、0.038cmol/kg和0.072 cmol/kg。应用该方法检测20份耕地实际土壤样品,与国标法相比,交换性盐基总量钙镁钠钾的测定值相对误差均小于2 %,满足土壤样品分析检测的要求。该方法操作简便、试剂用量少,准确度和精密度好,适用于大批量生态地球化学评价土壤样品中交换性盐基总量钙镁钾钠的测定。     

The application of INAA in a study of environment geochemistry on the Xizang (Tibet) Plateau,China

INAA as a routine analysis method has been used in a study of environment geochemistry on the Xizang (Tibet) Plateau in China, and 34 elements in soil samples were determined by INAA with both short and long irradiations. This paper presents some primary results from the study, including mean element concentrations in Tibetan soil, paterns of element distribution in soils developed from main types of parent materials on the plateau. The results confirm the expectation that soil formed in such cold and dry environment on the plateau retained the main geochemical characteristics of the parent materials. However, the results still imply the possible migration of some elements in different bio-climatic environments during the soil formation. The elements in the top soils, mainly the alkalis and alkaline earths, and also As, Br, etc., were enriched or depleted in varying degrees in proportion to their abundance in the parent materials.     

冠心病（心肌纤维化）微量元素谱的多元分析

用ＩＣＰ－ＡＥＳ分析了冠心病中心肌纤维化男、女患者血液中的１９种元素含量，结果通过因子分析得到男女不同性能别的判别元素谱、应用非线性映射得以二维空间图、男性分辨率达９６．６％，女性达８７．３％。     

New evidence from stable isotope for the uplift of mountains in northern edge of the Qinghai-Tibetan Plateau

New data of oxygen and carbonate isotope in calcite cements from Cenozoic rocks inthe Jianggelesayi area to reconstruct the uplift history of mountains in northern edge of the Qing-hai-Tibetan Plateau are presented. Analyses results show that rapid changes of δ~(18)O and δ~(13)C inthe calcite cement occurred in both the Early Oligocene and Early Miocene. Studies on sedimen-tary features indicate that a rapid up-coarsing of the sediments size occurred in the Early Miocene,and sedimentary velocity increased rapidly during the Pliocene and Early Quaternary. Thus, it issuggested that the uplift of mountains in the northern edge of the Qinghai-Tibetan Plateau initiatedfrom the Early Oligocene, and a rapid uplift occurred in the early stage of the Miocene, while thesharp difference in topography between the northern plateau and the Tarim Basin predominatelyformed later than the Miocene.     

Spectrophotometric Study of 1,2,7-Trihydroxyanthraquinone-Mg(II) Complex. Determination of Mg(II)

Abstract

The spectrophotometric study of violet complex Anthrapurpurin-Mg(II) in a basic medium and a hydroalcoholic solution was made (δ_max - 530 nm., ? = 3.5 × 10³ 1 mol^?1 cm^?1, stoichiometry 1:1, apparent constant of stability log K = 9. 26). A new method for the spectrophotometric determination of Mg(II) is proposed for concentrations between one and six ppm. Relative errors between replicate samples were 0.90 %.     

Study on the Surface Photovoltage and Fluorescence Properties of N, N-Bis(4-aminopheny)-1, 4 quinonenediimine Doped with H_4SiW_(12)O_(40)

Polyaniline, especially its acid-dopping composite material, is a kind of important photoelectric material due to its potential application in many fields1~3. However, it seems to be a problem that the polymers exhibit several deficiencies, including chemical and structural imperfections as a result of mislinkage, saturated sites, molecular weight distribution, the presence of the end groups and conformation defects. All of these defects affect the device efficiency and make it difficult to …     

A DFT Study of the Structures of Aux Clusters on a CeO2(111) Surface

Studying the structures of metal clusters on oxide supports is challenging due to their various structural possibilities. In the present work, a simple rule in which the number of Au atoms in different layers of Au_x clusters is changed successively is used to systematically investigate the structures of Au_x (x=1–10) clusters on stoichiometric and partially reduced CeO₂(111) surface by DFT calculations. The calculations indicate that the adsorption energy of a single Au atom on the surface, the surface structure, as well as the Au? Au bond strength and arrangement play the key roles in determining Au_x structures on CeO₂(111). The most stable Au₂ and Au₃ clusters on CeO₂(111) are 2D vertical structures, while the most stable structures of Au_x clusters (x>3) are generally 3D structures, except for Au₇. The 3D structures of large Au_x clusters in which the Au number in the bottom layer does not exceed that in the top layer are not stable. The differences between Au_x on CeO₂(111) and Mg(100) were also studied. The stabilizing effect of surface oxygen vacancies on Au_x cluster structures depends on the size of Au_x cluster and the relative positions of Au_x cluster and oxygen vacancy. The present work will be helpful in improving the understanding of metal cluster structures on oxide supports.     

二氧化钛(TiO2)表面能的理论研究

用密度泛函理论和虚拟原子轨道方法对二氧化钛-金红石(TiO2)(110)表面的表面能进行了理论计算. 结果表明, 二氧化钛的表面能与表面缺陷的百分率相关. 完整的表面具有最低的表面能, 表面能随着表面缺陷百分率的增大而升高, 这与自然环境下二氧化钛-金红石(TiO2)具有规整的(110)表面一致. 在光催化实验中利用二氧化钛表面的缺陷作催化剂需要考虑到表面的稳定性. 另一方面, 在完整的表面五配位Ti4+上填加氧原子与表面作用时, 表面能起初变化很小, 直到50%的五配位Ti4+被填充后表面能才开始升高.     

Study on the Chemistry and Structure of (Na(1−x)Bix)(Nb(1−y)Mny)O3 Ceramics by XPS, AES and EPMA

The (Na_1–xBi_x)(Mn_yNb_1–y)O₃ ceramics are new compounds, obtained for the first time, on the base of sodium niobate with substitution of bismuth manganite. It was shown that the solubility limit for Mn ions in sodium niobate lattice does not exceed 1% at. Therefore, the co-doping with Bi ions was proposed to increase this limit. Bismuth ions are expected to replace Na ions and to ensure charge compensation in the formed compound, thus enhancing possibility of accumulation of the Mn ions in solution without losing the appropriate electrical and optical properties. To study the morphology of produced ceramic four methods of sample characterization were used: X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), electron microprobe analysis (EPMA) and Scanning Electron Microscopy (SEM).     

Depth Profile Analysis on the Nanometer Scale by a Combination of Electron Probe Microanalysis (EPMA) and Focused Ion Beam Specimen Preparation (FIB)

Electron probe microanalysis (EPMA) offers high sensitivity and high accuracy in quantitative measurements of chemical compositions and mass coverages. Owing to the low detection limits of the wavelength-dispersive technique, monolayers with mass coverages of about 0.05µgcm^–2 can be detected. Assuming a density of 5gcm^–3 this corresponds to a thickness of 0.1nm. With these advantages in mind, EPMA was extended to depth profile analysis in the sub-micron range using a surface removal technique.The present paper shows how depth profile analysis can be improved by combining EPMA and the focused ion beam (FIB) technique. The focused ion beam system uses a Ga⁺ ion beam. The ion beam allows the milling of defined geometries on the nanometer scale, so that very shallow bevels with exactly defined angles in relation to the surface can be obtained. Low surface damage is expected due to low sputtering effects. Calibrated WDX measurements along the bevel deliver quantitative concentration depth profiles. First results obtained with this new combination of methods will be presented for a multilayered sample used in optical data storage.     

Density Functional Theory Study of the Point Defects on KDP (100) and (101) Surfaces

Surface defects are usually associated with the formation of other forms of expansion defects in crystals, which have an impact on the crystals’ growth quality and optical properties. Thereby, the structure, stability, and electronic structure of the hydrogen and oxygen vacancy defects (V_H and V_O) on the (100) and (101) growth surfaces of KDP crystals were studied by using density functional theory. The effects of acidic and alkaline environments on the structure and properties of surface defects were also discussed. It has been found that the considered vacancy defects have different properties on the (100) and (101) surfaces, especially those that have been reported in the bulk KDP crystals. The (100) surface has a strong tolerance for surface V_H and V_O defects, while the V_O defect causes a large lattice relaxation on the (101) surface and introduces a deep defect level in the band gap, which damages the optical properties of KDP crystals. In addition, the results show that the acidic environment is conducive to the repair of the V_H defects on the surface and can eliminate the defect states introduced by the surface V_O defects, which is conducive to improving the quality of the crystal surface and reducing the defect density. Our study opens up a new way to understand the structure and properties of surface defects in KDP crystals, which are different from the bulk phase, and also provides a theoretical basis for experimentally regulating the surface defects in KDP crystals through an acidic environment.     

Measurement of pressure distribution in the Plateau borders of fresh and aged foams

In the interpretation of foam ageing processes it is important to know the laws of fluid motion in the Plateau borders. In foams, the rate of fluid motion is determined, in principle, by the fluid viscosity, the static and dynamic surface tension, the shape of the capillaries and the pressure distribution. An attempt is made to investigate the role of these parameters experimentally. As a first step, the pressure and the pressure distribution were measured in the Plateau borders by liquid-filled manometers kept in contact with the Plateau borders through a porous plate. The pressure is always negative, and the pressure vs. time curves show maxima at the point of the start of draining. Draining starts when pressure difference drops to zero at the bottom of the foam container. After a sufficiently long time the pressure becomes equal to the hydrostatic pressure at the given level, i. e. _p=–gh, where is the density of the liquid andh is the height of the foam column measured from the bottom of the container.     

苯乙烯-甲基丙烯酸十六酯的共聚及降焦研究

利用响应面分析法对聚苯乙烯-甲基丙烯酸十六酯吸油树脂吸附卷烟焦油和烟碱的影响因素进行分析,拟合树脂的单体组成、交联度与致孔剂用量与吸附率间的回归方程,绘制响应面分析图,得到聚合工艺最佳优化条件:单体组成为0.6、交联度0.8%、致孔剂用量9.8%,在最佳条件下,树脂对焦油和烟碱的吸附率分别为37.23%、15.26%,对烟气中多环芳烃吸附率可达80%以上,整个抽吸过程都有吸附效果.     

Surface hydroxylation of poly(vinylidene fluoride) (PVDF) film

The surface of PVDF film was selectively modified by wet chemistry. Treatment with aqueous LiOH produced HF-elimination and the emergence of an oxygen-containing functionality. The XPS analysis clearly indicated the presence of ketone-, ether(epoxide)-, and alcohol motifs. The percentage of alcohols could be significantly increased by reduction of the ketones with NaBH₄ in 2-propanol, followed by reduction of the epoxides with DIBAL-H in hexane. Thus, the full treatment led to a PVDF surface displaying 7 to 16% of oxygen-containing units, of which about 60% consisted in alcohol motifs. The reactvity of the surface-displayed hydroxyl functions was assayed by radiolabeling with [³H]-Ac₂O. © 1997 John Wiley & Sons, Inc. J. Polym Sci A: Polym Chem 35: 1227–1235, 1997     

Comparing the Self-Assembly of Sexiphenyl-Dicarbonitrile on Graphite and Graphene on Cu(111)

A comparative study on the self-assembly of sexiphenyl-dicarbonitrile on highly oriented pyrolytic graphite and single-layer graphene on Cu(111) is presented. Despite an overall low molecule–substrate interaction, the close-packed structures exhibit a peculiar shift repeating every four to five molecules. This shift has hitherto not been reported for similar systems and is hence a unique feature induced by the graphitic substrates.