Imaging of chemical reactivity and buckled dimers on Si(100)2×1 reconstructed surface with noncontact AFM

We have investigated the force interactions between the Si tip and the Si(100)2×1 reconstructed surface in the noncontact atomic-force microscopy (AFM) measurement. We observed two types of frequency shift curves without and with discontinuity, similar to the Si(111)7×7 surface. The image contrast changes drastically whether the frequency shift curve shows discontinuity or not. In the case of the frequency shift curves without discontinuity, the noncontact AFM images almost reflect the surface topography including dimers and adsorbates. In the case of the frequency shift curves with discontinuity, they reflect strongly the chemical reactivity of surface. Furthermore, in the case of the frequency shift curves without discontinuity, for the first time, the stabilize-buckling of dimers induced by a defect can be observed. This suggests that the force interactions during the noncontact AFM measurement hardly influence the surface dynamics.     

[Nd(SSCNH2)4]-的电子结构 一种有机硫配位镧系络合物的模型阴离子

本文详细研究了络阴离子{Nd[SSCN(C_2H_5)_2]_4}~-的简化模型[Nd(SSCNH_2)_4]~-的电子结构和化学键合情况。从对键能的贡献看, 钕和硫原子之间的结合主要是离子性的, 但从电荷的重新分布看,应该认为共价结合对成键有一定贡献。σ键起主要作用, 对Nd—S和Nd—S′键来说, π键级只有σ键级的1/5～1/6。根据计算结果分析了为什么至今只合成了很少几种有机硫配位镧系络合物而存在大量稳定无机复合镧系硫化物的原因。建议了几种合成稳定的有机硫配位镧系络合物的可能途径。     

Surrogate atmospheric dust particles generated from dune soils in laboratory: Comparison with field measurement

Desert dust strongly influences the climate and the environment by altering the radiation budget, participating in atmospheric chemical reactions, and engaging the biogeochemical cycle. Studying its impacts requires knowledge of the physical and chemical properties of the original particles from the source origin. Unfortunately, the field collection of atmospheric samples in the desert is impractical. Fine surface soil is thus considered an alternative material from which to obtain the information applicable to dust particles from the desert soil. In this study, a laboratory system was set up to generate dust particles with simulated natural wind erosion processes from surface soils or directly from desert surfaces. Surface soils and field dust were simultaneously collected during a local blowing dust event. The comparison between the laboratory-generated dust and the field dust showed a consistent trend in particle size distribution and chemical composition. The chemical compositions were found to have explainable differences with the Certified Reference Materials for Asian dust (CJ-2). The laboratory-generated dust particles with the system could be applied as surrogates for soil-emitted dust in desert areas.     

Numerical study on heat and mass transfer mechanisms of Janus particle sedimentation considering corrosion

Janus particle is a research hotspot due to its novelty and settlement in acid liquid during wastewater treatment. Heat and mass transfer mechanisms of Janus particle sedimentation considering corrosion are numerically investigated based on immersed boundary lattice Boltzmann method. Chemical reaction heat ratio, Damkohler number, Peclet number, and particle number effects on temperature field, concentration field, Janus particle mass reduction, position, and velocity are investigated. The uniform particle has an equilibrium position of about 1/4 times the channel width for two corroded uniform particle settlement processes. The Janus particle horizontal position deviates from the uniform particle equilibrium position due to the force caused by nonuniform buoyancy and particle rotation. When the chemical reaction heat ratio is more than 1, the Janus particle horizontal position is closer to the channel centerline and has a positive deviation. However, the converse trend happens when the chemical reaction heat ratio is less than 1, and the Janus particle horizontal position has a negative deviation. The Janus particle horizontal position deviation magnitude increases with increasing Damkohler number and decreasing Peclet number. The horizontal position deviation phenomenon exists for the single corroded Janus particle and two corroded Janus particle settlement processes.     

微波消解-电感耦合等离子体质谱(ICP-MS)法测定化学原料药中痕量钯含量

建立了微波消解-电感耦合等离子体质谱(ICP-MS)法测定酒石酸氢可酮原料药中痕量元素钯含量的方法。样品经过微波消解,在优化ICP-MS仪器工作参数后,对样品中的钯含量进行测定。结果表明,方法检出限为0.002 9μg/mL,加标回收率在94.90%～103.4%,相对标准偏差小于3%。方法实现了对化学原料药中痕量钯的快速、简便、准确的检测。方法有望用于其它类似化学原料药中多种痕量元素的同时检测。     

改进的红外辐射-量热法测量O2(1△)绝对浓度

The absolute O2 （1Δ）concentration measurement performed for a singlet oxygen generator（SOG）by using the infrared radiation-calorimetry method is reported with a detailed discussion of its principle and related technique. The influence of O2 （1Δ）gas temperature variation is considered and the corresponding correction has been made,which is neglected by the previous researchers and may cause a significant error in the case of measurement for the large O2 （1Δ）flowrate. Furthermore,an automatically balanced Wheatstone bridge circuit,which is necessary for O2 （1Δ）detection on the SOG of short operation period,is designed and tested by measuring the heat capacity of oxygen. The final error analyses give out a total relative error of ±16% for the O2 （1Δ）concentration,which mainly arises from the measurements of infrared radiation,pressure and temperature at the optical cell.     

甘肃马衔山和田玉化学成分分析和产地判别研究

甘肃马衔山和田玉具有重要的宝玉石价值和考古文化价值,其中产地区分为甘肃马衔山和田玉的研究重点.通过测试分析马衔山和田玉的化学成分,对比其与国内主要产地和田玉的化学成分差异,建立微量元素产地判别模型,对甘肃马衔山和田玉的产地鉴别进行探究,为甘肃齐家文化中古玉器溯源提供数据支撑.以电子探针分析甘肃马衔山和田玉的主量元素,结...     

Darstellung und Struktur von U2Ta6O19, einer neuen Verbindung mit „Jahnberg‐Struktur”︁, sowie Anmerkungen zu den ersten Oxidchloriden in den Systemen Th/Nb/O/Cl und Th/Zr(Hf)/Nb/O/Cl

Synthesis and Crystal Structure of U₂Ta₆O₁₉, a New Compound with “Jahnberg‐Structure” and a Note to the First Oxide Chlorides in the Systems Th/Nb/O/Cl and Th/Zr(Hf)/Nb/O/Cl Black crystals of U₂Ta₆O₁₉ with hexagonal shape were obtained (at T₁) by chemical transport using HCl (p (HCl, 298 K) = 1 atm; silica tube) as transport agent in a temperature gradient (T₂ → T₁; 1000 °C → 950 °C) and using a mixture of UO₂, Ta₂O₅, and HfO₂ (or ZrO₂) (1 : 2 : 2) as starting materials (at T₂). For the structure determination the best result was achieved in space group P6₃/mcm (No. 193, a = 6.26(2) Å, c = 19.86(6) Å). U₂Ta₆O₁₉ is isotypical to Th₂Ta₆O₁₉. In the crystal structure each uranium atom is surrounded by oxygen atoms like a bi‐capped trigonal antiprism and tantalum atoms like a pentagonal bipyramid (CN = 7). Like the “Jahnberg Structures” both coordination polyhedra arrange themselves in separate layers (U–O‐polyhedra, in o‐, Ta–O‐polyhedra in p‐layers) so that in the direction of the c‐axis the sequence of layers is p‐p‐o. Using chemical transport it was possible to prepare the compounds Th₁₂Nb₁₆O₆₃Cl₂ and Th₈M₄Nb₁₆O₆₃Cl₂ (M = Zr, Hf), which are the first quaternary and quinquinary examples in these systems. They crystallize isotypically.     

Der Chemische Transport von Mischkristallen im System FeS/MnS/ZnS

Chemical Vapor Transport of Solid Solutions. 7. Chemical Vapor Transport of FeS/MnS/ZnS Mixed Crystals By means of chemical vapor transport using iodine as transport agent (900 → 800 °C) it is possible to prepare in the quasiternary system FeS/MnS/ZnS the mixed crystals (Fe,Mn,Zn)S (sphalerite and wurtzite type), (Fe,Mn)S(ZnS) (NaCl type) and FeS(MnS,ZnS) (NiAs type) in form of single crystals. Based on the composition of these phases the phase diagram for the system FeS/MnS/ZnS at 800 °C was drawn up. The incongruent transport process leads to the accumulation of ZnS in the crystallization zone.     

NMR Properties of Polylithiated C60

Endohedral, ¹³C, ⁷Li, and nucleus‐independent (NICS) chemical shifts are reported for selected Li_nC₆₀ isomers (n = 6, 12, 18) at the GIAO (gauge‐including atomic orbitals)‐SCF/DZP//BP86/3–21G level. Li₆C₆₀ closely resembles C₆₀^6– in terms of NMR criteria for aromaticity, as evidenced by an exceptionally high endohedral shielding. In contrast, nonaromaticity is indicated for Li₁₂C₆₀, based on a positive endohedral chemical shift. NICS and δ(endo) values very similar to those of Li₁₂C₆₀ are obtained for Li₁₈C₆₀. According to population analysis, indeed the same number of electrons are transferred to the fullerene cage in both cases. Endohedral chemical shifts, accessible via ³He NMR of the corresponding endohedral helium compounds, could thus be a valuable indicator for the extent of reduction of the C₆₀ molecule. Energetic estimates suggest that in the bulk, Li₁₂C₆₀ should be unstable with respect to decomposition into Li₆C₆₀ and lithium metal.