温度场在气电立焊机器人磁吸附设计中的应用

爬行式气电立焊机器人的磁吸附机构距离熔池较近,而且采用了磁悬浮铜滑块设计,考虑到温度对铁磁性的影响,研发中需要了解焊接温度场的分布状况.该文以Rykalin公式为基础,构建了气电立焊的温度场模型,采用Matlab7.0.4软件进行了数值计算和仿真,得到了焊接过程中的温度分布.研究表明,温度场对于爬行式气电立焊机器人的磁吸附机构基本没有影响,但是会直接影响到吸附铜滑块的设计,因此在计算悬浮磁块吸力的时候需要考虑温度系数.气电立焊温度场模型的建立为爬行式气电立焊机器人的磁吸附机构和磁悬浮铜滑块的设计提供了重要依据.     

自制固相微萃取探头用于分析大白菜中有机磷农药

采用溶胶-凝胶方法制备的聚甲基苯基乙烯基硅氧烷／羟基硅油（PMPVS／OH-TSO）固相微革取探头与气相色谱（GC）联用对大白菜样品中的有机磷农药（敌敌鼹、二嗪农、甲摹对硫磷、马拉硫磷和乙基对硫磷）进行了分析，同时优化了固相微革取的实验条件．该探头较商用探头萃取能力更强，方法的检出限低（1．01～2．56ng／g），重现性好（3．5％～9．9％），线性范围宽（2个数量级），对市售的大白菜样品进行了标准加入回收实验，5种有机磷农药的同收率分别为80．2％，90．3％，85．4％，81．9％和91.8％，     

全甲基化2,3,6-三-(O-2’-羟丙基)β-环糊精固定液热力学性质和分离机理

将合成的全甲基化２，３，６－三（Ｏ－２’－羟丙基）β－环糊精（ＰＭＨＰ－β－ＣＤ）固定液直接涂渍 在弹性石英毛细管柱内壁，１４组对映异构体、６组芳香族位置异构体化合物等在该柱上得到 满意分离。通过测定以上化合物在该柱上的热力学参数：焓、熵、自由能及焓变差、熵变差，探 讨了固定液对所测化合物的分子识别和色谱分离机理。结果表明，芳香族化合物的－△Ｓ值在 ＰＭＨＰ－β－ＣＤ柱上比 ＴＢ－β－ＣＤ高２０～３０ Ｊ／ｍｏｌ·Ｋ，构型效应明显，极性选择性也比后者高。     

Calix[4] open-chain crown ether-modified, vinyl-functionalized hybrid silica monolith for capillary electrochromatography

A novel calix[4] open-chain crown ether (p-tert-butylcalix[4]arene-1,3-bis(allyloxyethy) ether)-modified, organic-inorganic hybrid silica-based monolithic column possessing vinyl ligands for CEC is described. The monolithic silica matrix containing a vinyl functionality was synthesized by in situ cocondensation of tetramethoxysilane (TMOS) and vinyltrimethoxysilane (VTMS) via sol-gel process and chemically modified with calix[4] open-chain crown ether by free radical polymerization procedure using alpha, alpha'-azobisisobutyronitrile (AIBN) as an initiator. Morphology of the monolithic column was examined by SEM and the successful incorporation of calix[4] open-chain crown ether to the vinyl-hybrid monolith was characterized by infrared (IR) spectra. Compared with an unmodified vinyl-hybrid monolithic column, slightly stronger EOF at pH >7.5 was observed for this monolithic column due to the ionization of phenolic hydroxyls on the lower rim of calix[4]arene. VTMS/TMOS ratios in the reaction mixture were varied and 1:4 was found to be optimum to obtain homogeneous monolith with good permeability. The performance of the column was evaluated by nucleotides, beta-blockers, neurotransmitters, and PAHs as test solutes and compared with that of unmodified vinyl-hybrid monolithic column. Greatly improved column performance was obtained due to the host-guest interaction and intermolecular hydrogen bonding provided by the calix[4] open-chain crown ether moiety. The column efficiencies for neurotransmitters and nucleotides are up to 120 000 and 110 000 plates/m, respectively. Migration time and theoretical plate number reproducibilities were reasonable with RSDs less than 1.0 and 1.8% each for within column runs and not more than 7.2 and 8.6% each for column-to-column measurements, using four nucleotides as test solutes.     

Hydrothermal synthesis, structures, and physical properties of four new flexible multicarboxylate ligands-based compounds

Four new compounds of partially or wholly deprotonated 5,5'-(1,4-phenylenebis(methylene))bis(oxy)diisophthalic acid (H4L1) and 5,5'-(1,3-phenylenebis(methylene))bis(oxy)diisophthalic acid (H4L2), namely {[Co(L1)0.5] x (H2O)2}n (1), {[Mn(L1)0.5] x (H2O)2}n (2), {[Cu(H2L1)](mu2-bipy)}n (bipy = 4, 4'-bipyridyl) (3), and {[Zn2(L2)] x H2O}n (4) were synthesized in the presence or absence of auxiliary bipy ligand. Their structures have been determined by single-crystal X-ray diffraction analysis and further characterized by elemental analysis, IR spectra, and thermogravimetric analysis. Compounds 1 and 2 are isostructural and possess three-dimensional (3D) networks. In compound 3, multicarboxylate ligands and bipy ligands link Cu centers to generate a two-dimensional (2D) sheet structure which is further connected by intermolecular hydrogen bonds to form a 3D supramolecular structure. In compound 4, the Zn centers are connected by L2(4-) anions to generate a 3D framework. Magnetic susceptibility measurements indicate that compounds 1 and 2 exhibit antiferromagnetic coupling between adjacent Co(II) ions and Mn(II) ions. The photoluminescent properties of the free 4L1 and H4L2 ligands and compound 4 have been studied in the solid state at room temperature. Both ligands and compound 4 exhibit strong violet emissions. Compared with the fluorescent emission of the ligand, the emission of 4 is red-shifted and enhanced.     

Syntheses, structures, photoluminescence, and magnetic properties of phenanthrene-based carboxylic acid coordination polymers

Four new coordination complexes, M2(Htmopa)4(H2O)4 (M = Zn2+ (1), Mn2+ (2), (M(Htmopa)2(H2O)2)n (M = Ni2+ (3), Co2+ (4)), have been synthesized by the hydrothermal reaction of Htmopa (Htmopa = 2,3,6,7-tetramethoxyphenanthrene-9-carboxylic acid) with different transition metals at a suitable temperature. Single-crystal determinations revealed that 1 and 2 are isostructural and possess a dinuclear subunit, each connected into 3D networks by hydrogen bonds and C-H...pi interactions. 3 and 4 are also isostructural: the metal ions are bridged through water molecules and carboxylate oxygen atoms to form 1D wavelike double chains, and these double chains are further extended to a 3D network via hydrogen bonds and C-H...pi interactions. The photoluminescent properties of the free Htmopa ligand and its complexes have been studied in the solid state at room temperature. Both Htmopa and 1 exhibit strong blue emissions. Magnetic susceptibility measurements indicate that 2 and 3 exhibit antiferromagnetic coupling, whereas 4 shows a ferromagnetic coupling and exhibits a single-ion behavior of the Co II ion at a higher temperature range.     

环糊精-冠醚用作毛细管气相色谱手性固定相的研究

合成了一种新型的气相色谱固定相６－（１－苯并氮杂－１５－冠－５）－２,３,６－Ｏ－全甲基－β－环糊精,并用于一些对映体与芳香族位置异构体的分离。结果表明,新型固定相具有良好的选择性和拆分能力,显示了环糊精与冠醚对化合物分离的协同作用。     

基于深度学习的反无人机预警神经网络

为解决传统雷达探测设备面对"低小慢"无人机时产生的难检测与易突防问题,通过深度卷积神经网络对空中无人机进行实时识别,提取目标的类别与像空间位置信息;根据无人机像空间位置在时域下的变化趋势,绘制无人机飞行映射轨迹;利用长短期记忆网络对飞行映射轨迹进行预测,获取无人机在未来时域内的预测航迹方向,实现对无人机的预警跟踪、实时检测与轨迹推断。结果表明,所提出的算法中目标识别平均准确率可达到82%,轨迹预测平均准确率可达到80%计算速度可达到24帧/秒,可见能够在地基计算平台下对空中无人机进行实时精确预警,可以有效地防止识别领空内的非合作无人机渗透与突防。     

Analysis of fatty acids in sputum from patients with pulmonary tuberculosis using gas chromatography–mass spectrometry preceded by solid-phase microextraction and post-derivatization on the fiber

A method based on solid-phase microextraction (SPME) and post-derivatization on the fiber coupled to gas chromatography–mass spectrometry (GC–MS) was developed for the analysis of fatty acids in sputum from patients with pulmonary tuberculosis. The sputum specimens were digested, hydrolyzed, extracted, derivertized, injected and analyzed without cultivation or isolation of the microorganism. Under optimized conditions, the relative standard deviations (RSD, n = 5) for all analytes were below 17% and the limits of detection varied from 1.68 (C_24:0) to 150.4 μg L⁻¹ (C_12:0). Good linearity was observed for all the fatty acids studied except for C_12:0 within a wide concentration range of three orders of magnitudes with the correlation coefficients ranging from 0.91 (C_24:0) to 0.99 (C_14:0). Fatty acids in sputum specimens from 21 persons were directly analyzed using the proposed method. The results show that in all the sputum specimens from patients, who were clinically diagnosed with tuberculosis (TB), tuberculosis stearic acid (TBSA) was detected, while in all the sputum samples from persons without TB, TBSA was not found. The possibility of using the proposed method to detect mycobacterium tuberculosis (MTB) via the identification of TBSA in sputum was discussed. The comparison with other methods including sputum culture and microscopy of direct smears indicated that the proposed method is fast and sensitive for the analysis of fatty acids in sputum and offers an alternative for the detection of MTB in sputum.