Isotope effect of the stereodynamics in the reactions F+HCl→HF+Cl and F+DCl→DF+Cl

Using a new ground-state ab initio potential energy surface reported by Deskevich et al., the product polarizations in the reactions F+HCl→HF+Cl and F+DCl→DF+Cl were studied by employing the quasi-classical trajectory method. At a collision energy of 10 kcal/mol, the four generalized polarization-dependent differential cross-sections (2π/σ)(dσ₀₀/dω _t ), (2π/σ)(dσ₂₀/dω _t ), (2π/σ)(dσ₂₂₊/dω _t ) and (2π/σ)(dσ₂₁₋/dω _t ) were calculated in the center-of-mass frame. The distribution of the angle between k and j′, P(θ _r ), the distribution of the dihedral angle denoting the k-k′-j′ correlation, P(φ _r ), and the angular distribution of the product rotational vectors in the form of polar plots P(θ _r , φ _r ) were also calculated. The evident influence of isotope substitution on the product polarization is revealed. This effect may result from the different mass factors of the two reactions.     

Dissolved inorganic carbon and its isotopic differentiation in cascade reservoirs in the Wujiang drainage basin

Three cascade reservoirs, built in different periods of time in the Wujiang drainage basin, were investigated in this study. Samples were taken at the surface and also at 20, 40, 60, 80 m depths in front of the dams in April, July, October of 2006 and January of 2007. Chemical parameters were calculated and the concentrations of dissolved inorganic carbon [DIC] and its isotopic composition （δ613CDIC） were determined. In surface waters, the δ613CDIC values are high in summer and autumn and low in winter and spring, while the DIC concentrations are relatively low in summer and autumn and relatively high in winter and spring. In the water column, the DIC concentrations increase while δ613CDIC values decrease with water depth. DIC in various reservoirs is significantly different in isotopic composition from that in natural rivers, but is close to that in natural lakes. In addition, in surface waters, the δ613CDIC values tend to become lower whereas the nutrition level tends to become higher with increasing age of the reservoirs. The conclusion is that after dam blocking, changes took place in the hydrochemical properties of river water, and the impounding rivers developed toward lakes and swamps. In addition, differentiation in DIC isotopic composition may be used to some extent to trace the evolution process of a reservoir.     

Electrical anisotropy of orientedtrans-polyacetylene undoped and doped with SO3

We use extended Huckel methods of molecular orbitds and crystal orbitals (EHMO/CO) to calculate the two-dimensional band structures of highly oriented trans-polyacetylene (PA) undoped and doped with SO3. According to the energy band theory of solids, we explain the changes of band gap (Eg) and bandwidth (BW) from undoped PA to SO3-doped PA, and discuss the electrical anisotropy of oriented trans-polyacetylene doped with SO3. The calculated results show that the conductivity anisotropy ratio (σ///σ⊥) is determined by Eg and BW in the directions both parallel (σ//) and perpendicular (σ⊥) to the PA chains, respectively. The conductivity anisotropy ratio σ///σ⊥ decreases when PA is doped with SO3, because the dopant plays a conjugated bridge role between the interchains of PA, and makes the dopant itself and PA chains show a strong interchain coupling. The theoretical results for undoped and doped PA are in good agreement with experimental ones.     

Hydrophobic mechanism and criterion of lotus-leaf-like micro-convex-concave surface

According to the principle that the contact angle of liquid droplet always increases on a limited liquid-solid interface,it is suggested that the integration of many small-size limited liquid-solid interfaces results in the increase of the hydrophobicity of lotus-leaf-like micro-convex-concave surfaces.Mathematical equations of the stability of liquid-droplets on the surface of lotus-leaf-like structure were established.The relationship between the theoretical critical-radius of the void of micro-convex-concave surface and the nature of the solid and the liquid was drawn.The three conditions of realizing hydrophobicity were described.The result of computation has shown that when the radius of the void of micro-concave-convex surface is less than the theoretical critical-radius r c,the droplets may always be in a stable state on the solid surface with the contact angle greater than 90°.Theminimum area of the liquid-solid interface and low surface energy of solids are important factors in realizing hydrophobicity.The effective work of adhesion W a ’ was proposed as a criterion for measuring the hydrophobic ability of the solid surface.     

海浪波谱仪微波散射模型

【目的】建立与观测数据相符的海浪波谱仪(SWIM)散射模型。【方法】利用Kirchhoff近似以及准镜面散射理论,建立从海浪方向谱映射到海浪波谱仪后向散射截面(σ°)的散射模型,并利用热带降雨测量卫星(TRMM)所搭载的降雨雷达(PR)提供的低入射角下的后向散射截面数据,对模型进行检验。【结果】准镜面散射模型结合高阶Gram-Charlier级数型海表斜率概率密度函数,模拟的雷达后向散射截面与入射角的关系在降雨雷达的0~18°入射角范围内与实测数据一致。【结论】海浪波谱仪的信号散射可利用准镜面散射模型结合高阶Gram-Charlier级数型海表斜率概率密度函数来描述。     

Sm-Nd dating and Nd-Sr isotopic characteristics of the Shimian ophiolite suite, Sichuan Province

By measuring the Sm-Nd and Rb-Sr isotopic compositions of harzburgite and gabbro from Shimian ophiolite suite, we got the whole rock Sm-Nd isochron age of (938±30) Ma (2?), and the ??Nd of 7.6±0.8 (2?), which shows that the ophiolite was formed at the Early Neoproterozoic. The obvious change (0.70209-0.70708) of ISr values of the ophiolite is caused by the meteoric hydrothermal alteration. The high ? Nd values indicate that the primitive magma was derived from the intense depleted mantle reservoir. It is suggested that this area was in a back-arc basin environment during the Early Neoproterozic.     

整形器对SHPB入射波形影响规律的定量研究

波形整形器是实现分离式霍普金森压杆（SHPB）实验恒应变率加载的重要手段之一,为研究整形器对入射波形的影响规律,本文以紫铜、黄铜、铝等软材料为研究对象,在37 mm霍普金森压杆（SHPB）设备上开展了整形器直径和厚度、撞击杆速度、长度等因素对入射波形状影响规律的实验研究,并结合数值模拟仿真研究与量纲分析,给出了入射波T₁和T₂拐点的量纲一应力、量纲一时间的定量表达式,T₁拐点的量纲一应力σ/σ*与量纲一参数Y/σ*,（d/D_b）2和h/L_b分别呈线性关系;T₂拐点的量纲一时间t/t*与量纲一参数h/L_b、Y/σ*都是呈线性关系的.      

Formate and acetate as recorded in a mid－latitude glacier in west China

Formic (HCOOH) and acetic (CH3COOH) acids are the chief carboxylic compounds in the troposphere[1]. Although weak acids, they contribute significantly to the free acidity, ionic balance of precipitation and the chemical reactions in the atmosphere, especially in the remote areas[2—4]. General sources for formate and acetate have been identified in the past 3 decades although a satisfactory source attribution is lacking to explain atmospheric observations[5]. Possible sources include veget…     

Synthesis, Characterization and Properties of LiFePO4/C Cathode Material

Lithium iron phosphate coated with carbon (LiFePO₄/C) was synthesized by improved solid-state reaction using comparatively lower temperature and fewer sintering time. The carbon came from citric acid, which acted as a new carbon source. It was characterized by thermogravimetry and differential thermal analysis (TG/DTA), X ray diffractometer (XRD), Element Analysis (EA) and Scanning electron microscope (SEM). We also studied the electrochemical properties of the material. The first discharge capacity of the LiFePO₄/C is 121 mAh·g⁻¹ at 10 mA·g⁻¹, at room temperature. When the current density increased to 100 mA·g⁻¹, the first discharge capacity decreased to 110 mAh·g⁻¹ and retained 95% of the initial capacity after 100 cycles. The LiFePO₄/C obtained shows a good electrochemical capacity and cycle ability at a large current density. Foundation item: Supported by the National Natural Science Foundation of China (20071026) Biography: ZHOU Xin-wen (1980-), male, Master, research direction: inorganic material chemistry.     

Simultaneous in-situ determination of U-Pb age and trace elements in zircon by LA-ICP-MS in 20 μm spot size

Simultaneous in-situ determination of U-Pb ages and 20 trace elements of three international zircon standards （91500, GJ1 and TEMORA 1） and one laboratory zircon standard （SK10-2） separated from Cenozoic fine-grained gabbro was carried out on quadrupole ICP-MS equipped with 193 nm excimer laser in 20 μm spot size. The weighted mean ^206Pb/^238U ages of 91500, GJ1 and TEMORA 1 are 1064.4±4.8 Ma （2σ）, 603.2±2.4 Ma （2σ） and 418.2±2.4 Ma （2σ）, respectively. The relative standard deviations （RSDs） of ^206Pb/^238U ages （2σ） are less than 2.2% for single measurements and 0.6% for weighted means. The obtained weighted mean ^206Pb/^238U ages of three standard zircons agree with the recommended values within 2σrerror. The weighted mean ^206Pb/^238U age of SK10-2 is 31.42=0.25 Ma （2σ） and the RSDs of ^206Pb/^238U ages （2σ） are between 2.4% and 5.7% for single measurements and less than 0.8% for weighted mean. The obtained weighted mean ^206Pb/^238U age is in good agreement with the age obtained by Yuan （2004）. Trace element concentrations of NIST612 and NIST614 obtained under the same LA-ICP-MS operating conditions agree with the recommended values within analytical error. The results indicate that it is possible to measure U-Pb age and trace elements simultaneously by LA-ICP-MS in a small spot size of 20μm.     

Effects of anions on the biosorption of microelement cations by macroalga <Emphasis Type="Italic">Enteromorpha prolifera</Emphasis> in single- and multi-metal systems

The results of research on the effects of anions on the biosorption of microelement cations by the edible marine macroalga Enteromorpha prolifera in singleand multi-metal systems are discussed in this paper. It was shown that the maximum biosorption capacity (qmax) in a single-metal system of Co(II) ions decreased in the following sequence: Cl- (46.0 mg g-1) > SO42- (42.8 mg g-1) > NO3- (41.9 mg g-1). In multi-metal systems, in which the ratios of Cl-, NO3-, and SO42- were 0:0:4, 1:1:2, 3:0:1, and 4:0:0, there were clear differences among the biosorption capacities. In all the examined systems (other than the 0:0:4 system), inhibition of the binding of microelement cations by the macroalga was observed. In all the systems, the highest value of qmax was obtained for Cu(II) cations; the value ranged from 31.9 mg g-1 in 0:0:4 (SO42- only) to 18.2 mg g-1 in 4:0:0 (Cl-only).     

QSPR between Physical-Chemical Properties and Molecule Parameters of Alkanes

A set of molecule parameters, namely, N, N′, p, q, n, were used to express the structures of alkanes. A correlative model was established between certain physical-chemical properties and molecular parameters of alkanes by regression method. Eight physical-chemical properties, such as evaporation heat （△vHm^20）, density（D^20 ）, capacity （C^20）, surface tension （δ^20）, boiling point （Tb）, critical temperature（Tc）, critical pressure（Pc） and critical volume（Vc）, of fifty-six C3-C16 alkanes were calculated directly from the model in this paper. The calculated values are in good accordance with the literature ones reported for alkanes, and the correlation coefficients （R） equal or exceed 0.99 . The research results indicate that the principle of the method is simple and clear, the method is practical, the correlativity is excellent, and the predicted data are credible.     

The formation depth of coesitebearing eclogite, Dabie UHPM zone, China, modified by tectonooriginal additional hydrostatic pressure

The knowledge that hydrostatic pressure is equal to the gravity value of the overlying rocks in studying a dynamic state of certain underground site is argued. It is suggested that the stress field T in the crust is a combination or superposition of total hydrostatic pressure P with differential stress σ , and the total hydrostatic pressure P at any point in the crust comprises two parts: one is spherical stress tensor PG caused by the gravity, and the other is spherical stress tensor Ps caused by tectonic stress; therefore P could not be attributed to the gravity of overlying rocks only. The results obtained by a finite-element simulation indicate that the tectono-original additional hydrostatic pressures Ps decrease gradually from the compressive zone (Pcs) to the shear zone (PSHs) and to the tensile zone (PTs), i. e. PCS>PSHs> PTs in the same depth. On the basis of the above-mentioned research, the method of measurement and calculation of metal logenetic depth corrected by Ps is established, i.e. first tectonic additional hydrostatic pressure Ps is removed from general hydrostatic pressure P to get PG, gravity additional pressure, then accordingly the depth data are measured and calculated. The plastic deformation of garnet in coesite-bearing eclogite, quartz eclogite and garnet amphibo-lite of the ultrahigh-pressure metamorphic (UHPM) complex in the Yingshan County in Dabie Mt. is studied by the transmission electron microscope (TEM). It is shown that the garnets have ductile deformation in the metamorphic condition of eclogite and amphibolite facies. Microstructures of the garnet vary greatly among coesite-bearing eclogite, quartz eclogite and garnet amphibolite. The tectonic principal stress in three-dimensional space and the tectonic additional hydrostatic pressure are reconstructed by differential stress and strain ratio (α) of garnet in minor coesite-bearing eclogite, then the gravity and thickness of overlying rocks are determined. The formation depth of ≥ 32.09-32.106 km of the coesite-bearing eclogite in Yingshan County in the Dabie UHPM zone is obtained from difference PG which comes from P minus Ps, Ps = (σ1 + σ2 + σ3) /3. The value of P is 2.8 GPa resulting from Qz-coes geobarmeter. This result is at all different from other researchers' conclusion that the formation depth of eclogite in Dabie UHPM zone is ≥100 km by the method of weight/ special weight (W/SW). The strong tectionic action makes a great contribution to the formation of e-clogite in the Dabie UHPM zone at so shallow depth of about 32 km, therefore it is thought that attention should be paid to the tectonc-original additional hydrostatic pressure in the study on UHPM zone.     

Giant magneto-optical faraday effect of nanometer Fe-In<Subscript>2</Subscript>O<Subscript>3</Subscript> granular films

The giant magneto-optical Faraday effect of nanometer ferromagnetic metal-semiconductor matrix Fe-ln2O3 granular films prepared by the radio frequency sputtering are studied. The result shows that the Faraday rotation angle θF value of the granular film samples with Fe volume fraction x = 35% is of the order of 10^5（°）/cm at room temperature. Temperature dependence of the Faraday rotation angle θF of Fe0.35（In2O3）0.65 granular films shows that θF value below 10 K increases rapidly with the decrease of the temperature, and when T= 4.2 K, θF value is 106（°）/cm. Through the study of the dependence of low field susceptibility on temperature and the hysteresis loops at different temperatures, it has been found that when the temperature decreases to a critical point Tp = 10 K, the transformation of state from ferro-agnetic to spin-glass-like occurs in Fe0.35（In2O3）0.65 granular films. The remarkable increase of the Faraday rotation angle θF value of Fe0.35（In2O3）0.65 granular films below 10 K seems to arise from the sp-d exchange interaction of the granular film samples in the spin-glass-like state.     

Synthesis of layered LiMnO2 byin situ oxidation-intercalation and a study of the reaction mechanism and electrochemical performance

Using Mn(OH)₂ as precursor, LiOH as lithiating agent and (NH₄)₂S₂O₈ as oxidant, layeredo-LiMnO₂ was obtained by a novel method—in situ oxidation-intercalation under mild conditions (80 °C). The product was characterized by XRD, ICP, TEM and⁷Li-NMR. The results reveal that orthorhombic LiMnO₂ with high purity and good crystallinity can be obtained by this method. During electrochemical tests, a LiMnO₂/Li cell shows an initial reversible capacity of 208 mAh · g⁻¹ and a reversible capacity of 180 mAh · g⁻¹ after 30 cycles at room temperature.     

The first observation of Mo5+ in the passivation layer of Mo2N

Molybdenum nitride powder with S_g of 115 m² · g¹ (passivated) has been prepared by a temperature programmed reaction of MoO₃in H₂/N₂ mixture. It exhibited high catalytic activity in CO oxidation at low temperature. XPS, EPR and LRS studies have shown the existence of mixed valence states of Mo ions, especially Mo⁵⁺ ion (g(tT=1.932,g||=1.892) observed for the first time, in the passivation layer of molybdenum nitride. A surface Superoxide species, O₂ (g = 2.001, Raman band 1 124 cm¹), was found to be produced accompanying the transformation of Mo⁵⁺/Mo⁴⁺ redox pair. Evidence has been given to suggest that this surface superoxide might be responsible for CO oxidation over Mo₂N catalyst.     

Holocene climatic and environmental changes recorded in Baahar Nuur Lake core in the Ordos Plateau, Inner Mongolia of China

A 5.3 m lake core was drilled in Baahar Nuur Lake in the Ordos Plateau, and measurements of meangrain size, organic δ 13C (δ 13Corg), organic carbon content (TOC), C/N, carbonate content, carbonate δ 13C(δ 13Ccar) and δ 18O (δ 18Ocar) were conducted for retrieving the Holocene chronosequence of climaticchanges based on 15 AMS 14C dates. The record documented four major stages of climate change inthe Ordos Plateau: (IV) a cold and dry condition before ～7.65 14C ka BP; (III) a warm and humid stagebetween ～7.65 and ～5.40 ka BP; (II) a generally drier and cooler climate since ～5.40 ka BP with twohumid events occurring from ～4.70 to ～4.60 ka BP and from ～4.20 to ～3.70 ka BP, and (I) a dry climatecharacterized by complete desiccation of the lake after 3.70 ka BP. Stage III can be further divided intothree sub-stages: (IIIa) a warm and humid episode from ～7.65 to ～6.70 ka BP, (IIIb) a warm and relativelydry episode from ～6.70 to ～6.20 ka BP, and (IIIc) the magthermal and maghumid episode of the Holo-cene from ～6.20 to ～5.40 ka BP.     

Long-chain alkenones in sulfate lakes and its paleoclimatic implications

Long-chain alkenones are ubiquitous in marinesediments. The relationship between alkenone unsatura-tion and temperature has been proved by field studies andcultures of E. huxleyi[1] and G. oceanica[2]. As an idealproxy for sea surface paleotemperature estimation, theU37 index is widely applied to reconstructing paleotem- K 'perature in most oceanographic settings[3—10]. The suc-cessful progresses in the ocean invoked the researchers’attention to the study of LCAs in the liminic system.Cr…     

石墨相氮化碳表面包覆改善锂离子电池正极材料LiCoO2电化学性能的研究

通过简单的固相法和液相法,分别制备出石墨相氮化碳（g-C₃N₄）表面改性的商品化LiCoO₂复合材料,采用扫描电子显微镜观察改性后的材料,发现g-C₃N₄都均匀地包裹在LiCoO₂表面。两种g-C₃N₄-LiCoO₂复合材料被用作锂离子电池的正极材料,电化学测试结果显示,固相法制得的g-C₃N₄-LiCoO₂复合材料在0.2 C的倍率下充放电测试,首次比容量达167 mA·h·g^-1,循环80次后,比容量仍达132 mA·h·g^-1,高于未经g-C₃N₄包裹的纯LiCoO₂（98 mA·h·g^-1）;液相法制得的Y-C₃N₄-LiCoO₂复合材料循环稳定性明显优于同类材料,循环80次后容量保持率均在95%以上。试验证实,g-C₃N₄表面改性的策略具有一定的实用价值,改性后,材料优异的电化学性能归因于g-C₃N₄的包裹处理,这不仅增强了固体电解质界面（SEI）的稳定性,也抑制了锂离子嵌入/脱出电极材料时引起LiCoO₂体积的变化。