Axially chiral C2-symmetric N-heterocyclic carbene (NHC) palladium complexes-catalyzed asymmetric arylation of aldehydes with arylboronic acids

Chiral C₂-symmetric N-heterocyclic carbene (NHC) palladium diaquo complexes 5a–c and the chiral C₂-symmetric NHC-palladium complexes 5d and 5e prepared from (R)-BINAM or H₈-(R)-BINAM could be used as the catalysts for the enantioselective arylation of arylaldehydes with arylboronic acids in which NHC-Pd complex 5a was found to be fairly effective in this reaction to give the corresponding adducts in moderate enantioselectivities along with moderate to good yields.     

In-site observation of the crystallization of nylon-6 mediated by the interfacial hydrogen bonds

Hydrogen bonds exist in many polymer systems and play a large role in the physical and chemical properties. In this study, nylon-6, which consists of repeated amide groups and contains large number of hydrogen bonds, is chosen as an example. Meanwhile, the oxidized unzipped MWCNTs (μCNTs) with oxygenated species such as carboxyl and hydroxyl groups are used as mediator to regulate the crystallization process of nylon-6 thin films. In-site experimental techniques, including Fourier transform infrared spectroscopy, X-ray diffraction spectroscopy, and polarized optical microscopy were utilized to get more direct insights on the crystallization mechanism of nylon-6 and μCNTs systems.     

S波段100MW速调管的研制

中国科学院电子学研究所研制的S波段100 MW速调管是国内目前峰值功率最高的速调管,其最大的技术特点是,它有两个输出波导和两个输出窗。在工作电压414.7 kV、工作电流583 A、脉冲宽度2μs和重复频率25 Hz的条件下,该管的峰值功率达到了110.85 MW,效率和增益分别达到了45.8%和58 dB。该管的工作稳定性好,束流通过率高(直流和高频通过率分别为99%和97%),工作中未出现明显的打火和振荡现象。本文详细地介绍了该管的设计考虑和测试结果。     

Syntheses and Crystal Structures of LnIII–CuI Coordination Polymers

Four three‐dimensional heterometallic coordination polymers, [Ln₂Cu₄I₃(IN)₇(H₂O)]_n ( 1 , 2 ) and [LnCu_3.5I₃(IN)_3.5(H₂O)₃]_n · nH₂O ( 3 , 4 ) [HIN = isonicotinic acid, Ln = Nd ( 1 ), Gd ( 2 ), La ( 3 ), Eu ( 4 )] were hydrothermally synthesized by using lanthanide oxides, isonicotinic acid, copper chloride, and potassium iodide. The different molar ratio of raw materials results in two distinct types of three‐dimensional frameworks of compounds 1 – 4 . The structure of compounds 1 and 2 are constructed by the layer modules of [Ln₂(IN)₇(H₂O)]_n^n– and Cu₄I₃ clusters, whereas that of compounds 3 and 4 are built by dimeric Ln₂(IN)₆(H₂O)₆ and layered polymeric [Cu₇I₆]_nⁿ⁺ units.     

Synthesis of N-t-Butyl-N'-Aminocarbonyl-N-(Substituted) Benzoylhydrazine Containing a -Aminoalkylphosphonate Groups

A variety of novel N-t-butyl-N'-aminocarbonyl-N-(substituted)benzoylhydrazines containing a -aminoalkylphosphonate groups were synthesized by the addition of N-t-butyl-N-(substituted)benzoylhydrazines to a -isocyanatoalkylphosphonates, which were synthesized by the reaction of a -aminoalkylphosphonates with triphosgene in good yields. The structures of products including by-products were confirmed by 1H NMR, 31P NMR, IR, mass spectroscopy, and elemental analysis.     

Trapped instability and vortex formation by an unstable coastal current

This paper addresses the instability of a two-layer coastal current in a quasigeostrophic model; the potential vorticity (PV) structure of this current consists in two uniform cores, located at different depths, with finite width and horizontally shifted. This shift allows both barotropic and baroclinic instability for this current. The PV cores can be like-signed or opposite-signed, leading to their vertical alignment or to their hetonic coupling. These two aspects are novel compared to previous studies. For narrow vorticity cores, short waves dominate, associated with barotropic instability; for wider cores, longer waves are more unstable and are associated with baroclinic processes. Numerical experiments were performed on the f-plane with a finite-difference model. When both cores have like-signed PV, trapped instability develops during the nonlinear evolution: vertical alignment of the structures is observed. For narrow cores, short wave breaking occurs close to the coast; for wider cores, substantial turbulence results from the entrainment of ambient fluid into the coastal jet. When the two cores have opposite-signed PV, the nonlinear regimes range from short wave breaking to the ejection of dipoles or tripoles, via a regime of dipole oscillation near the wall. The Fourier analysis of the perturbed flow is appropriate to distinguish the regimes of short wave breaking, of dipole formation, and of turbulence, but not the differences between regimes involving only vortex pairs. To explain more precisely the regimes where two vortices (and their wall images) interact, a point vortex model is appropriate.     

Preparation,morphology, and biolabeling of fluorescent nanoparticles based on conjugated polymers by emulsion polymerization

Novel nanoparticles based on conjugated polymer with good fluorescent properties were synthesized by Suzuki coupling reaction using certain surfactants as one kind of special emulsion polymerization. The luminescent properties of the prepared nanoparticles could be controlled by selecting different monomers. Without using substances comprising any heavy metal element, these fluorescent nanoparticles show very good biocompatibility with cells, thus showing potential applications in cell biolabeling, drug delivery tracing, organic light‐emitting diodes, flat displays, and other areas. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Influence of the KTP crystal boundary temperature on conversion efficiency in high power green laser

The influence of the KTiOPO4 (KTP) crystal boundary temperature on conversion efficiency in high power green laser has been studied theoretically and experimentally. Temperature distribution inside the KTP crystal has been analyzed by solving the thermal conductivity equation. From the temperature distribution inside the KTP crystal, we have calculated the optimal phase-matching angles of the type-Ⅱ KTP crystal as a function of temperature. The second-harmonic conversion efficiency as a function of temperature has also been calculated. In the experiment, two KTP crystals with different phase-matching angles were used in the intrcavity-frequency-doubled resonator. When the boundary temperature of KTP-A (φ = 23.6°,θ = 90° under the condition of 27 ℃ temperature) was setting at 4 ℃, a maximum green light power of 104 W was generated at repetition rate of 20.7 kHz and pulse width of 132 nm with pumping current of laser diode of 18.3 A, leading to 10.2% optical-to-optical conversion efficiency. When KTP-B crystal (φ = 24.68°, θ = 90° under the condition of 80 ℃ temperature) was employed, an average output power of 110 W at 532 nm has been achieved with values of 11.5% and 2% for the optical-to-optical efficiency and the instability, respectively. The optimal boundary temperature of this KTP crystal has been found to be 48.8 ℃.     

基于插件的远程监控系统设计与实现

远程监控系统广泛应用于网络监控、网络管理及远程作业等领域，本文论述了远程监控系统的系统模型、工作流程以及实现技术。这种系统实现简单、快捷，易维护、易升级，并具有较强的系统稳定性。     

Germanium pMOSFETs with Schottky-barrier germanide S/D, high-/spl kappa/ gate dielectric and metal gate

Schottky-barrier source/drain (S/D) germanium p-channel MOSFETs are demonstrated for the first time with HfAlO gate dielectric, HfN-TaN metal gate and self-aligned NiGe S/D. The drain drivability is improved over the silicon counterpart with PtSi S/D by as much as /spl sim/5 times due to the lower hole Schottky barrier of the NiGe-Ge contact than that of PtSi-Si contact as well as the higher mobility of Ge channel than that of Si.