Synthesis and characterization of organotin(IV) compounds with Schiff base of o-vanillin-2-thiophenoylhydrazone

Seven Schiff base adducts of organotin(IV), RSnLCl₂, which L is o-vanillin-2-thiophenoylhydrazone, and R is n-C₄H₉ (1), Me (2), Ph (3), and [R₂SnL], which L is o-vanillin-2-thiophenoylhydrazone, R is n-C₄H₉ (4), Me (5), Ph (6), PhCH₂ (7) have been synthesized. Those products were characterized by elemental analysis, IR, ¹H, ¹³C and ¹¹⁹Sn NMR spectra. The crystal and molecular structures of compounds 1, 4, and 6 have been determined by X-ray single crystal diffraction. In the crystal of compound 1 the tin atom is rendered six-coordinate in a distorted octahedral configuration by coordinating with the N atom of the Schiff base ligand, in compounds 4 and 6 the central tin atoms are five-coordinate in distorted trigonal-bipyramidal geometry and the comparison of the IR spectra reveal that disappearance of the bands assigned to carboxyl unambiguously conforms the ligand coordinate with the tin atom in enol form.     

Generation of minimally persistent circle formation for a multi-agent system

In this paper, two methods of generating minimally persistent circle formation are presented. The proposed methods adopt a leader-follower strategy and all followers are firstly motivated to move into the leader＇s interaction range. Based on the information about relative angle and relative distance, two numbering schemes are proposed to generate minimally persistent circle formation. Distributed control laws are also designed to maintain the desired relative distance between agents. The distinctive features of the proposed methods are as follows. First, only 2n - 3 unilateral communication links for n agents are needed during the circle formation process and thus the communication complexity can be reduced. In addition, the formation topology is kept fixed for the whole motion and achieves a self-stability property. Finally, each follower keeps a regualr interval with its neighbors and the formation converges to a uniform circle formation. Simulation results are also provided to demonstrate the effectiveness of the proposed methods.     

The effect of pre-test deformation on dough rheology

We show that the strain involved in forming a dough specimen before testing will often radically alter the measured rheological properties in shear and in elongation if these pre-strains are greater than about 0.5 (Hencky strain). It is shown that this may be accounted for by changing the G(1) value used in the damage function model to a relevant value.     

Calculation of the photoelectron spectra under the scaling transform

By solving time-dependent Schrödinger equation, the dependence of photoelectron energy spectra on the binding energy of targets, wavelength and intensity of laser pulse is exhibited and a scaling law of kinetic energy spectra of both the direct and the rescattered photoelectrons is concluded. The scaling law provides a convenient tool to determine the equivalent photoionization process of various atoms or molecules in various laser fields. The verification of the scaling law by independent methods provides an incontestable support to the validity of the scaling law.     

一种新型交替迭代算法用于农药GC-MS信号快速分析

化学计量学算法为重叠GC-MS信号解析提供了有效手段. 免疫算法(IAs)可根据标准样品的信号(色谱或质谱)对重叠GC-MS信号进行解析并得到重叠信号中各组分的信息. 但是标样信号与实际测量信号之间的差别会造成解析结果出现偏差. 针对标样信号与测量信号不一致的问题, 作者提出了一种交替迭代算法用于重叠GC-MS测量信号的直接解析. 该方法在不提供标样信号的情况下可以解析出组分的质谱和色谱信息. 计算过程中, 采用随机产生的质谱作为初始输入, 利用最小二乘和IA算法交替计算质谱和色谱, 直到满足终止条件. 采用所建立的方法对40种组分的农药混合物进行了分析, 使用快速升温程序在10 min保留时间内得到了全部组分的色谱和质谱信息.     

负载阿霉素的丝蛋白纳米微球

丝蛋白具有良好的生物相容性, 生物可降解性以及无免疫原性. 利用丝蛋白独特的亲疏水多嵌段共聚物结构特征和构象转变机制, 通过乙醇诱导和冷冻相结合的自组装方法制备得到丝蛋白纳米微球后, 再在纳米微球表面包覆阿霉素, 成功获得了负载阿霉素的丝蛋白纳米载药微球. 该载药丝蛋白纳米微球的尺寸为350～400 nm, 具有圆球形态并且分散性能良好; 其载药率为4.6%, 包封率大于90%, 在磷酸缓释溶液中的释放可达7天以上. 此外, 研究发现其缓释行为具有pH响应性, 在pH=5.0的磷酸缓冲溶液中的缓释量明显大于在pH=7.4的缓冲液中. 体外细胞培养结果显示, 纯丝蛋白纳米微球基本没有细胞毒性; 而负载有阿霉素的丝蛋白纳米微球能明显抑制癌细胞(Hela细胞)的增殖, 且24 h和48 h的培养结果表现出与单纯药物相同的药效. 因此, 该负载阿霉素的丝蛋白纳米微球在临床癌症淋巴化疗方面具有潜在的应用价值.     

Wind induced deformation and vibration of a Platanus acerifolia leaf

Deformation and vibration of twig-connected single leaf in wind is investigated experimentally.Results showthat the Reynolds number based on wind speed and lengthof leaf blade is a key parameter to the aerodynamic problem.In case the front surface facing the wind and with an increase of Reynolds number,the leaf experiences static deformation,large amplitude and low frequency sway,reconfiguration to delta wing shape,flapping of tips,high frequencyvibration of whole leaf blade,recovery of delta wing shape,and twig-leaf coupling vibration.Abrupt changes from onestate to another occur at critical Reynolds numbers.In casethe back surface facing the wind,the large amplitude andlow frequency sway does not occur,the recovered delta wingshape is replaced by a conic shape,and the critical Reynoldsnumbers of vibrations are higher than the ones corresponding to the case with the front surface facing the wind.Apair of ram-horn vortex is observed behind the delta wingshaped leaf.A single vortex is found downstream of theconic shaped leaf.A lift is induced by the vortex,and thislift helps leaf to adjust position and posture,stabilize bladedistortion and reduce drag and vibration.     

Superfluid response in heavy fermion superconductors

Motivated by a recent London penetration depth measurement [H. Kim, et al., Phys. Rev. Lett. 114, 027003 (2015)] and novel composite pairing scenario [O. Erten, R. Flint, and P. Coleman, Phys. Rev. Lett. 114, 027002 (2015)] of the Yb-doped heavy fermion superconductor CeCoIn₅, we revisit the issue of superfluid response in the microscopic heavy fermion lattice model. However, from the literature, an explicit expression for the superfluid response function in heavy fermion superconductors is rare. In this paper, we investigate the superfluid density response function in the celebrated Kondo–Heisenberg model. To be specific, we derive the corresponding formalism from an effective fermionic large-N mean-field pairing Hamiltonian whose pairing interaction is assumed to originate from the effective local antiferromagnetic exchange interaction. Interestingly, we find that the physically correct, temperature-dependent superfluid density formula can only be obtained if the external electromagnetic field is directly coupled to the heavy fermion quasi-particle rather than the bare conduction electron or local moment. Such a unique feature emphasizes the key role of the Kondo-screening-renormalized heavy quasi-particle for low-temperature/energy thermodynamics and transport behaviors. As an important application, the theoretical result is compared to an experimental measurement in heavy fermion superconductors CeCoIn5 and Yb-doped Ce_1?xYb_xCoIn₅ with fairly good agreement and the transition of the pairing symmetry in the latter material is explained as a simple doping effect. In addition, the requisite formalism for the commonly encountered nonmagnetic impurity and non-local electrodynamic effect are developed. Inspired by the success in explaining classic 115-series heavy fermion superconductors, we expect the present theory will be applied to understand other heavy fermion superconductors such as CeCu₂Si₂ and more generic multi-band superconductors.     

基于DSP的航天器压力变化检漏仪的设计

航天器的密封性能是极其重要的指标之一,利用压力变化方法进行舱体密封性检漏是保障其密封性的重要技术手段;设计研制小型压力变化检漏仪对满足航天器检漏设备小型集成化、高精度的迫切需求是十分重要的;以DSP为数据的核心处理器,分析绝压和差压具有温度补偿方法,设计基于485通信接口实现数字绝压传感器的数据采集,采用250Ω的高精度电阻接入电流环的方法实现差压传感器的信号调理,通过ADS1247高精度24位数模转换器实现差压信号的采集;并采用恒流供电和电阻比测量原理实现对两路热敏电阻温度传感器的测量;各信号经DSP中固化的压力变化检漏算法集中处理,得到被测物体的漏率值,检测结果通过LCD显示。所研制集绝压、差压和温度多参量监测于一体的检漏仪,经过温度、压力、检漏试验等测试,验证了其精度和检漏能力满足要求;研究结果表明：所研制的检漏仪小巧,精度高,可靠性高,可实现压力、温度、漏率等多参量的同时监测,漏率检测的最大相对误差为19.3%,相对不确定度小于2%,可有效地解决航天器泄漏检测的问题。     

Cu原子掺杂调控三聚氰胺在Au(111)表面自组装结构

The doping effect of Cu on the self-assembly film of melamine on an Au(111) surface has been investigated with scanning tunneling microscopy (STM). The evaporated Cu adatoms occupy the positions underneath the amino groups and change the hydrogen bonding pattern between the melamine molecules. Accordingly, the self-assembly structure has changed stepwise from a well-defined honeycomb into a track-like and then a triangular structure depending on the amount of Cu adatoms. The interaction between Cu adatom and melamine is moderate thus the Cu adatoms can be released upon mild heating to around 100℃. These findings are different from previous observations of either the coordination assembly or the physically trapped metal adatoms.