Catalytic removal of <Emphasis Type="Italic">tert</Emphasis>-butyldimethylsilyl (TBS) and tetrahydropyranyl (THP) groups from protected alcohols by NO<Superscript>+</Superscript>BF<Subscript>4</Subscript><Superscript>−</Superscript> in methanol

An effective, catalytic method has been developed to remove TBS and THP groups from protected alcohols. TBS and THP ethers were selectively cleaved using a catalytic amount of NO⁺BF₄^– (5 mol%) in methanol at room temperature.     

Regional Δ<Superscript>14</Superscript>C patterns and fossil fuel derived CO<Subscript>2</Subscript> distribution in the Beijing area using annual plants

The level of atmosphericΔ14C and the fossil fuel derived CO 2 concentration in the Beijing area from May to September,2009, were systematically analyzed based on radiocarbon(14C)measurements of annual plants by accelerator mass spectrometry(AMS). The results show that the maximumΔ14C in Beijing was 29.6‰±2.2‰,and the minimum was–28.2‰±2.5‰,with a trend of decreasingΔ14C from the outer suburbs to inner suburbs to the urban center.This trend correlates well with increases in fossil fuel derived CO2 caused by human activities such as population density,industrial emissions and traffic,with lower values of atmosphericΔ14C associated with more intensive human activities.The fossil fuel derived CO 2 concentrations from May to September, 2009,ranged from 3.9±1.0 ppm to 25.4±1.0 ppm.It was calculated that each additional 1 ppm of CO2 from fossil fuels depleted the atmosphericΔ14C by approximately 2.70‰.This study suggests that 14C measurements of annual plants by AMS provide an effective method to rapidly trace fossil fuel derived CO2.     

Distribution of <Emphasis Type="Italic">δ</Emphasis><Superscript>18</Superscript>O in surface snow along a transect from Zhongshan Station to Dome A,East Antarctica

Surface snow samples were collected during the 14th (1997/1998) and 24th (2007/2008) Chinese National Antarctica Research Expeditions along a transect from Zhongshan Station to Dome A. The stable oxygen isotope ratios of these samples were measured to investigate their relationships with temperature and geographical parameters (latitude, longitude, altitude and distance to the coast). The results reveal a strong positive correlation (R=0.945) between δ¹⁸O and mean annual temperature, with a gradient of 0.84‰°C ^–1, which is a little higher than that in Terre Adelie Land. Regression analyses also show that the δ¹⁸O of surface snow is strongly correlated with distance to the coast (R=0.942), latitude (R=0.942), and altitude (R=0.941). But no significant correlation was found between δ¹⁸O and longitude in study area. Altitude should be the most important factor influencing the δ¹⁸O distribution because of distinctive topography. The δ¹⁸O-altitude and T-altitude gradients along this transect are determined to be –1.1‰/100 m and 1.31°C/100 m, respectively.     

Electronic properties and stabilities of methoxy-substituted Lindqvist polyoxometalates [Nb<Subscript>2</Subscript>W<Subscript>4</Subscript>O<Subscript>19</Subscript>CH<Subscript>3</Subscript>]<Superscript>3−</Superscript> by DFT

The electronic properties and stabilities of five [Nb₂W₄O₁₈OCH₃]³⁻ isomers have been investigated using a density functional theory method. The results show that the isomer with the methoxy group occupying a bridging position between two tungsten atoms (two tungsten atoms in the plane that contains two niobium atoms) in the [Nb₂W₄O₁₈OCH₃]3⁻ framework is the most stable isomer in acetonitrile. The stability of the one-electron-reduced isomers changes little. The most stable one-electron-reduced isomer has the methoxy group occupying a bridging position between niobium atoms in the [Nb₂W₄O₁₈OCH₃]⁴⁻ framework. The M-Ob (M = Nb, W; b denotes bridging) bond lengths in anions in which the metal atoms are connected by a methoxy group are longer than those in [Nb₂W₄O₁₉]⁴⁻. The highest occupied molecular orbitals (HOMO) in [Nb₂W₄O₁₉]⁴⁻ mainly delocalize over the bridging oxygen atoms of two niobium atoms and two tungsten atoms located in the equatorial plane, and the bridging oxygen atoms on the axial surface. The lowest unoccupied molecular orbitals (LUMO) of [Nb₂W₄O₁₉]⁴⁻ are mainly concentrated on the tungsten atoms and antibonding oxygen atoms. Methoxy substitution modifies the electronic properties of the [Nb₂W₄O₁₈OCH₃]³⁻ isomers. The HOMOs in the five isomers formally delocalize over the bridging oxygen atoms, which are distant from the surface containing the methoxy group and four metal atoms. The LUMOs delocalize over the d-shells of the four metal atoms that are close to the methoxy group, and the p-orbitals of oxygen. One-electron reduction occurred at the tungsten atoms, not the niobium atoms.     

Structural dependences of the <Emphasis Type="Italic">η</Emphasis><Superscript>6</Superscript> complexes of 3-amino-9-ethylcarbazole with chromium tricarbonyl fragment on third-order optical nonlinearities

Degenerate four-wave mixing measurements, using the 35 ps pulses at 532 nm, have been employed to investigate the third-order nonlinear optical parameters of two chromium tricarbonyl complexes η6-bonded to 3-amino-9-ethylcarbazole at either the NH2-substituted aryl ring （1） or the unsubstituted ring （2） and their precursor 3-amino-9-ethylcarbazole （AECz）. The second-order hyperpolarizability y of the compounds 1 and 2 were found to be 42.9×10^-31 and 35.9×10^-31 esu, respectively, approximately one order of magnitude greater than AECz. The relation between the molecular structure and second-order hyperpolarizability of the compounds I and 2 was explored in detail based on the three-level model and the density functional theory （DFT） calculation. The theoretical results indicate that the spatial distribution of electron density has the profound role in the third-order nonlinear optical properties.     

Fatty-acids and their <Emphasis Type="Italic">δ</Emphasis><Superscript>13</Superscript>C characteristics of seep carbonates from the northern continental slope of Gulf of Mexico

Here we reported the fatty-acids and their δ¹³C values in seep carbonates collected from Green Canyon lease block 185 (GC 185; Sample GC-F) at upper continental slope (water depth: ~540 m), and Alaminos Canyon lease block 645 (GC 645; Sample AC-E) at lower continental slope (water depth: ~2200 m) of the Gulf of Mexico. More than thirty kinds of fatty acids were detected in both samples. These fatty acids are maximized at C₁₆. There is a clear even-over-odd carbon number predominance in carbon number range. The fatty acids are mainly composed of n-fatty acids, iso-/anteiso-fatty acids and terminally branched odd-numbered fatty acids (iso/anteiso). The low δ¹³C values (−39.99‰ to −32.36‰) of n-C₁₂:0, n-C₁₃:0, i-C₁₄:0 and n-C₁₄:0 suggest that they may relate to the chemosynthetic communities at seep sites. The unsaturated fatty acids n-C_18:2 and C_18:1△⁹ have the same δ¹³C values, they may originate from the Beggiatoa/Thioploca. Unlike other fatty acids, the terminally branched fatty acids (iso/anteiso) show lower δ¹³C values (as low as −63.95‰) suggesting a possible relationship to sulfate reducing bacteria, which is common during anaerobic oxidation of methane at seep sites.     

Modification of MgO·Al<Subscript>2</Subscript>O<Subscript>3</Subscript> spinel inclusions in Al-killed steel by Ca-treatment

The modification of MgO·Al₂O₃ spinel inclusions in Al-killed steel by Ca-treatment has been studied by industrial trials and thermodynamic calculations. In the industrial trials, samples were taken systematically during the refining process in which the molten steel was treated by calcium, and the characters of the inclusions were analyzed using scanning electron microscopy (SEM) and energy dispersive spectra (EDS). The effects of Ca-treatment were evaluated by tracking the compositions of the inclusions. The results show that the modification of MgO·Al₂O₃ spinel inclusions by Ca-treatment is effective and the transformation sequence of the inclusions during the refining is Al₂O₃→MgO·Al₂O₃→liquid complex inclusions. The modification of spinel inclusions by Ca-treatment was calculated by FactSage6.0 utilizing its free-energy minimization routines. The results of thermodynamic calculations indicate that spinel inclusions are easier to be modified than Al₂O₃ inclusions and the spinel inclusions in 30CrMo steel would transform to liquid complex inclusions when the content of dissolved Ca in the molten steel exceeds 1×10⁻⁶. Also, the results show that adding more calcium into the molten steel would lower the contents of Al₂O₃ and MgO and increase the CaO content of the inclusions, while the change in SiO₂ content is little.     

Thermodynamic analysis on the formation mechanism of MgO·Al<Subscript>2</Subscript>O<Subscript>3</Subscript> spinel type inclusions in casing steel

MgO·Al₂O₃ spinel type inclusions in casing steel were analyzed by scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). The results show that there are three forms. One is pure MgO·Al₂O₃ spinel, another is the composite oxide of the Mg-Al-Ca-Si-O system, and the third is the complex with oxide as a core covered by sulfide. The formation mechanisms were studied. The influences of slag basicity and vacuum degree on the magnesium content during the vacuum treatment of molten steel and furnace lining in molten steel were calculated with the coexistence theory of slag structure. The results show that the magnesium content increases with the increase in slag basicity and aluminum content in molten steel, and decreases with the increase in CO partial pressure.     

A phase field study for influence of elastic energy on L1<Subscript>0</Subscript>→L1<Subscript>2</Subscript> transient ordering in Ni<Subscript>75</Subscript>Al<Subscript>17</Subscript>Zn<Subscript>8</Subscript>

The influence of the elastic energy on L1₀→L1₂ transient ordering transformation was investigated by microscopic phase field method. It is found that there are three stages experienced in atomic ordering: solute clustering+L10 short range ordering → L1₀ long range ordering → L1₂ long range ordering. Before the formation of the high ordered L1₂ phase, it has firstly taken place the transformation from matrix to L1₀ phase, and then held the L1₀→L1₂ secondary transformation. Elastic energy is proved to take little effect on the stage of short range ordering, but as the elastic energy is multiplied, it obviously shortened the course of the solute clustering, and speeded up the proceeding of the L1₀ long range ordering transition. Accordingly, the increased elastic energy also strengthens the single crystalline directionality of L1₀ phase projecting on 2D plane and makes the ordered degree of Al and Zn atoms enhanced. With the temperature elevation, Al’s and Zn’s ordered degree decreased in L10 phase.     

An α-expansin, <Emphasis Type="Italic">VfEXPA1</Emphasis>, is involved in regulation of stomatal movement in <Emphasis Type="Italic">Vicia faba</Emphasis> L.

The wall loosening of guard cells differs from other types of plant cells. However, the regulation of wall loosening during stomatal movement is poorly understood. VfEXPA1 is an α-expansin gene cloned from Vicia faba epidermal strips. Expression of VfEXPA1 is regulated by darkness and submergence, and is not affected by light and abscisic acid (ABA). In situ hybridization showed that VfEXPA1 is expressed primarily in the guard cells. Overexpression of VfEXPA1 in transgenic tobacco accelerated light-induced stomatal opening, and increased both transpiration and photosynthetic rates under favorable growth conditions. Our results indicate the guard cell-expressed expansin VfEXPA1 plays an important role in regulation of stomatal opening.     

Atomic decomposition in L p (ℝ n ) (1 <p < 2)

An atomic decomposition in L^p ( 1 <p < 2) with tent space is given.     

Second organic aerosol formation by irradiation of α-pinene-NO<Subscript>x</Subscript>-H<Subscript>2</Subscript>O in an indoor smog chamber for atmospheric chemistry and physics

Ozone（O3） and secondary organic aerosol （SOA） are considered to be the most serious secondary air pollutants of concern in most metropolitan areas, as well as for Beijing. In this study, 03 and SOA formation potential of α-pinene, the most abundant biogenic VOCs, is investigated at Tsinghua Indoor Chamber Facility. The experiments were conducted under atmospheric relevant HCs/NOx ratios in both presence and absence of ammonia sulfate seed aerosol. A Scanning Mobility Particle Sizer system （3936, TSI） and a Condensation Particle Counter （3010, TSI） were used to study the SOA formation and a gas chromatograph （GC） equipped with a DB-5 column and a flame ionization detector （FID） was used to measure α-pinene simultaneously. The results show that the presence of ammonia sulfate seed aerosol did not change the formation trend of 03, but significantly contribute to SOA formation. A strong linear relationship （r^2 = 0.90） between SOA yield enhancement （△Y＊） and surface concentration of seed aerosol （PM1, s）has been found, denoting that the PMi, s is the control factor for SOA yield enhancement. And the possible reason for the enhancement is acid-catalyzed heterogeneous reactions.     

黄瓜;多糖;自由基;清除;抗氧化性

建立了热水提取、乙醇沉淀、Sevage法除蛋白、有机溶剂分离精制提取黄瓜多糖的方法,并用蒽酮一硫酸比色法测定其含量;采用超氧阴离子自由基、羟基自由基、二苯代苦味肼基自由基(DPPH·)体系,对黄瓜多糖的抗氧化活性进行了研究,结果表明:黄瓜多糖对DPPH·、·OH and O2-·具有较强的清除能力,与其浓度呈线性关系.     

评电视连续剧&lt;&lt;弘一大师&gt;&gt;

本文对２０集电视连续剧《弘一大师》创意和内容提出了批评意见,主要原因是;片名既为“弘一大师”,却化费了１６集之多,,描述他出家前如幻的虚构情节,具有严重歪曲弘一大师之嫌;从整个内容看,纂改了弘一大 师生活的那段历史,张冠李戴,移花接森,对佛教的内涵,编导本身既知之不详,却假借“弘一大师”之口误导观众。文章还在其它方面对该剧提出了异议,如对人的称呼,弘一大师的分相等。     

&lt;&lt;傲慢与偏见&gt;&gt;中的“小中见大“

“小”题材可以反映出“大问题”。小说通过那些“乡间村庄里的三、四户人家”的家务事，尽显１８世纪末１９世纪初尚未受到资本主义工业浪潮中冲击的英国乡镇中的阶段状况和经济关系。     

对&lt;&lt;语言学概论&gt;&gt;教学的再认识

语言学的一般理论主要是在研究、分析印欧语系语言的基础上建立起来的，没有很好概括到汉藏语系尤其是汉语研究成果和材料，和汉语语言学研究难免是会有所脱节的。而《语言学概论》作为普通语言学的一门基础理论课自开设以来，在教学实际中一直存在着不少的意见和问题。本文结合多年的教学实际，就《语言学概论》这门课该讲什么，不该讲什么，如何把语言学的一般理论和汉藏语系的语言特别是汉语的实际相结合，如何吸收国外语言学研究     

李君;武砚斐;郭颖兰;王卓;河南省南

3000,473000,473000自杀;;倾向因素;;因素分析;;统计学;;青少年目的了解南阳市青少年自