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81.
A coordination polymer of [Cd{5-(NO2)sal}2(2,2′-bipy)]n(5-(NO2)sal=5-nitrosalicylate, 2,2′-bipy=2,2′-bipyridine) was synthesized by hydrothermal reaction and characterized by elemental analysis, IR and X-ray diffraction single crystal structure analysis. The title complex crystallizes in monoclinic with space group C2/c, a=2.730 8(16) nm, b=1.272 3(5) nm, c=0.674 5(3) nm, β=96.73(2)°, V=2.327(2) nm3, Z=4, R=0.022 2, wR=0.057. The 5-nitrosalicylate anions doubly bridge the Cd(Ⅱ) atoms to form one-dimensional polymeric chain with the repeated eight-membered ring units (Cd-O-C-O)2. The crystal structure is stabilized by intra- and interchain hydrogen bonds interactions. CCDC: 694568. 相似文献
82.
BAIYIN Meng-he LIANG Feng-ying XU Xiao-qing TA Na NA Mi-la BAI Wu-yun BAO Yong-sheng 《高等学校化学研究》2011,27(6):915-918
Sheet Rb2HgSnS4 was synthesized solvothermally and characterized by X-ray single crystal diffraction. The compound is comprised of sheets with admantane-like [Hg2Sn2S10]8– units. The crystals belong to the space group C2/c, with the unit cell parameters a=1.1063(2) nm, b=1.1071(2) nm, c=1.5741(3) nm, a=90°, β=100.13(3)°, γ=90°. A reflectance spectroscopy study reveals the nature of the semiconductor with an energy of 2.1 eV for the compound. 相似文献
83.
Dr. Thomas Schwarze Janine Riemer Holger Müller Leonard John Prof. Dr. Hans-Jürgen Holdt Prof. Dr. Pablo Wessig 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(53):12412-12422
Over the years, we developed highly selective fluorescent probes for K+ in water, which show K+-induced fluorescence intensity enhancements, lifetime changes, or a ratiometric behavior at two emission wavelengths (cf. Scheme 1, K1 – K4 ). In this paper, we introduce selective fluorescent probes for Na+ in water, which also show Na+ induced signal changes, which are analyzed by diverse fluorescence techniques. Initially, we synthesized the fluorescent probes 2 , 4 , 5 , 6 and 10 for a fluorescence analysis by intensity enhancements at one wavelength by varying the Na+ responsive ionophore unit and the fluorophore moiety to adjust different Kd values for an intra- or extracellular Na+ analysis. Thus, we found that 2 , 4 and 5 are Na+ selective fluorescent tools, which are able to measure physiologically important Na+ levels at wavelengths higher than 500 nm. Secondly, we developed the fluorescent probes 7 and 8 to analyze precise Na+ levels by fluorescence lifetime changes. Herein, only 8 (Kd=106 mm ) is a capable fluorescent tool to measure Na+ levels in blood samples by lifetime changes. Finally, the fluorescent probe 9 was designed to show a Na+ induced ratiometric fluorescence behavior at two emission wavelengths. As desired, 9 (Kd=78 mm ) showed a ratiometric fluorescence response towards Na+ ions and is a suitable tool to measure physiologically relevant Na+ levels by the intensity change of two emission wavelengths at 404 nm and 492 nm. 相似文献
84.
基于时域有限差分法(FDTD)建立了松质骨的超声背散射仿真系统,研究了骨小梁材料特性对超声背散射信号的影响。首次得到松质骨中的超声背散射系数(BSC)和积分背散射系数(IBC)随骨小梁材料参数(密度、拉梅常数、黏度系数及声阻抗系数)的变化关系。研究结果表明,IBC随骨小梁密度的增加而增加;BSC和IBC随拉梅常数的增加而增加、随第一黏度系数的增加而近似线性地减小,第二黏度的变化对背散射信号的影响很小;背散射参数随阻抗系数的增加而减小。说明松质骨中的超声背散射特性不仅受骨矿密度(BMD)和骨微结构的影响,还与骨小梁的材料参数密切相关。研究结果有利于理解松质骨中超声的背散射特性,对松质骨骨质状况的评价有一定帮助。 相似文献
85.
K. Nimptsch R. Süß T. Riemer A. Nimptsch M. Schnabelrauch J. Schiller 《Journal of chromatography. A》2010,1217(23):3711-3715
Thin-layer chromatography (TLC) is a simple, fast and inexpensive separation method. Unambiguous identification of the TLC spots is, however, often a problem. Here we show for the first time that oligosaccharides (derived from dextran, alginate, hyaluronan and chondroitin sulfate) can be characterized by matrix-assisted laser desorption and ionization time-of-flight (MALDI-TOF) mass spectrometry (MS) directly on a TLC plate. The applied oligosaccharides were either commercially available or obtained from the polysaccharides by HCl-induced hydrolysis. Normal phase TLC was followed by MALDI-TOF MS subsequent to matrix deposition. It will be shown that high quality mass spectra can be obtained that enable unequivocal assignments. It will also be shown that the high content of formic acid in the solvent system does not confer major problems but is responsible for the partial formylation of the analyte and minor N-acetyl loss from hyaluronan and chondroitin sulfate. 相似文献
86.
87.
A Highly K+‐Selective Fluorescent Probe – Tuning the K+‐Complex Stability and the K+/Na+ Selectivity by Varying the Lariat‐Alkoxy Unit of a Phenylaza[18]crown‐6 Ionophore
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Dr. Thomas Schwarze Radu Schneider Janine Riemer Prof. Dr. Hans‐Jürgen Holdt 《化学:亚洲杂志》2016,11(2):241-247
A desirable goal is to synthesize easily accessible and highly K+/Na+‐selective fluoroionophores to monitor physiological K+ levels in vitro and in vivo. Therefore, highly K+/Na+‐selective ionophores have to be developed. Herein, we obtained in a sequence of only four synthetic steps a set of K+‐responsive fluorescent probes 4 , 5 and 6 . In a systematic study, we investigated the influence of the alkoxy substitution in ortho position of the aniline moiety in π‐conjugated aniline‐1,2,3‐triazole‐coumarin‐fluoroionophores 4 , 5 and 6 [R=MeO ( 4 ), EtO ( 5 ) and iPrO ( 6 )] towards the K+‐complex stability and K+/Na+ selectivity. The highest K+‐complex stability showed fluoroionophore 4 with a dissociation constant Kd of 19 mm , but the Kd value increases to 31 mm in combined K+/Na+ solutions, indicating a poor K+/Na+ selectivity. By contrast, 6 showed even in the presence of competitive Na+ ions equal Kd values (KdK+=45 mm and KdK+/Na+=45 mm ) and equal K+‐induced fluorescence enhancement factors (FEFs=2.3). Thus, the fluorescent probe 6 showed an outstanding K+/Na+ selectivity and is a suitable fluorescent tool to measure physiological K+ levels in the range of 10–80 mm in vitro. Further, the isopropoxy‐substituted N‐phenylaza[18]crown‐6 ionophore in 6 is a highly K+‐selective building block with a feasible synthetic route. 相似文献
88.
超声兰姆(Lamb)波在结构缺陷检测方面愈来愈受到重视,但目前Lamb波的应用局限于单信号源激励,单通道接收的方法,容易受到噪声干扰,其后续的信号分析处理也比较复杂。本文旨在采用多通道Lamb波对板状结构中的裂纹进行定量分析与诊断。在铝板的表面凿刻出不同深度的凹槽作为裂纹,通过线阵换能器采集在一定传播距离内的多通道Lamb波信号,并采用二维傅里叶变换分析在不同深度的裂纹下,Lamb波模式能量的变化规律。结果表明,相对于完好铝板中的Lamb波信号,裂纹的存在会使Lamb波发生模式转换现象,并且转换模式能量百分比随裂纹深度的增加而线性增加。其结果为Lamb波评价板状结构中的裂纹状况提供了一种可能的方法。 相似文献
89.
90.