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91.
Developing an effective method for improving the reproducibility of positive temperature coefficient(PTC) effect is of great significance for large-scale application of polymer based PTC composites, owing to its contribution to the security and reliability. Herein, we developed a carbon black(CB)/high density polyethylene(HDPE)/poly(vinylidene fluoride)(PVDF) composite with outstanding PTC reproducibility, by incorporating 1-octyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide([OMIm][NTf_2]) into the composite. After multiple repeated temperature cycles, the PTC performance of as-prepared material keeps almost unchanged and the varition of resistance at room temperature is less than 7%. Our studies revealed that [OMIm][NTf2] contributes to the improvement of PTC reproducibility in two ways:(i)it acts as an efficient plasticizer for refining the co-continuous phase morphology of HDPE/PVDE blends;(ii) it inhibits the crystallization of PVDF through the dilution effect, leading to more overlaps of the volume shrinkage process of HDPE and PVDF melt which results in the decrease of interface gap between HDPE and PVDF. This study demonstrated that ionic liquids as the multifunctional agents have great potential for improving the reproducibility in the application of the binary polymer based PTC composites. 相似文献
92.
电化学与核磁共振波谱联用技术(EC-NMR)可以实时监测电化学反应过程,从分子水平阐释反应机理,是一种非常有前景的无损在线检测技术。本文首次报道以硅基硼掺金刚石(Si/BDD)作为工作电极的原位EC-NMR三电极单室电解池的设计和制作。研究表明,由于尺寸12.5 mm × 1.2 mm × 0.5 mm的Si/BDD电极在核磁检测区的体积较小且电极材料厚度较薄,因此该电极对射频场的阻碍较小,对磁场均匀性破坏也相应较小。运用自制的EC-NMR电解池并以经典的对苯二酚(QH 2)电氧化生成对苯二醌(Q)作为模型体系,原位研究了该电化学反应的整个动态过程。在1.2 V恒电位下电解0.1 mol·L-1 QH2 64分钟,监测到位于6.83 ppm处的Q特征峰逐渐生成,反应过程中核磁谱峰未发生裂分或明显的展宽。结果表明,应用本文所设计并制备的原位EC-NMR电解池,可有效对电化学反应物和产物进行定性、定量分析,将可在后续的电化学原位核磁波谱研究中发挥重要作用。 相似文献
93.
YUAN Mengjia WANG Xia CHEN Long ZHANG Mingxing HE Linwei MA Fuyin LIU Wei WANG Shuao 《高等学校化学研究》2021,37(3):679-685
As a rising star among porous solid materials, covalent organic frameworks(COFs) with excellent properties including but not limit to facilely controllable structure, high porosity, and multi-chemical functionality represent significant potential for efficient 127Xe/85Kr capture and separation. In this study, through tuning the length of the organic ligands, two-dimensional(2D) COF mate-rials with identical connection group but different pore properties, denoted as ATFG-COF and TpPa-COF with AA-stacking model and TpBD-COF with AB-stacking model were synthesized and tested for Kr and Xe adsorption for the first time. Adsorption measurements indicate that the narrower pore apertures and higher porosity are conducive for COF materials to capture Xe and Kr. Furthermore, the Henry's constant, isosteric heat of adsorption(Qst), and ideal adsorbed solution theory(IAST) selectivity of ATFG-COF, the pore size of which is closest to the kinetic diameter of the Xe atom(0.41 nm) among 2D COF materials, were carried out based on the single component sorption isotherms. The results illustrate that the high isosteric heat values of Xe/Kr adsorption on ATFG-COF are 25 and 16 kJ/mol at room temperature, respectively. Henry's law predicts that the selectivity factor of Xe to Kr is 6.07, consistent with the adsorption selectivity(ca. 6) calculated based on the IAST. 相似文献
94.
Sheida Esmail Tehrani Long Quang Nguyen Giulia Garelli Bettina M. Jensen Tautgirdas Ruzgas Jenny Emnéus Stephan Sylvest Keller 《Electroanalysis》2021,33(12):2516-2528
A highly sensitive amperometric Prussian blue-based hydrogen peroxide sensor was developed using 3D pyrolytic carbon microelectrodes. A 3D printed multielectrode electrochemical cell enabled simultaneous highly reproducible Prussian blue modification on multiple carbon electrodes. The effect of oxygen plasma pre-treatment and deposition time on Prussian blue electrodeposition was studied. The amperometric response of 2D and 3D sensors to the addition of hydrogen peroxide in μM and sub-μM concentrations in phosphate buffer was investigated. A high sensitivity comparable to flow injection systems and a detection limit of 0.16 μM was demonstrated with 3D pyrolytic carbon microelectrodes at stirred batch condition 相似文献
95.
96.
97.
Long Cheng Haonan Yang Xingyu Chen Guozhen Liu Dr. Yanan Guo Prof. Gongping Liu Prof. Wanqin Jin 《化学:亚洲杂志》2021,16(20):3162-3169
Graphene oxide (GO) is a promising two-dimensional building block for fabricating high-performance gas separation membranes. Whereas the tortuous transport pathway may increase the transport distance and lead to a low gas permeation rate, introducing spacers into GO laminates is an effective strategy to enlarge the interlayer channel for enhanced gas permeance. Herein, we propose to intercalate CO2-philic MIL-101(Cr) metal-organic framework nanocrystals into the GO laminates to construct a 2D/3D hybrid structure for gas separation. The interlayer channels were partially opened up to accelerate gas permeation. Meanwhile, the intrinsic pores of MIL-101 provided additional transport pathways, and the affinity of MIL-101 to CO2 molecules resulted in higher H2/CO2 diffusion selectivity, leading to a simultaneous enhancement in gas permeance and separation selectivity. The MIL-101(Cr)/GO membrane with optimal structures exhibited outstanding and stable mixed-gas separation performance with H2 permeance of 67.5 GPU and H2/CO2 selectivity of 30.3 during the 120-h continuous test, demonstrating its potential in H2 purification application. 相似文献
98.
99.
Zhen Long Dongping Yu Yanfang Liu Nana Du Yanduo Tao Lijuan Mei Zhimou Guo Xinmiao Liang 《Analytica chimica acta》2015
This study investigated the influence of organic sample solvents on separation efficiency of basic compounds under strong cation exchange (SCX) mode. The mixtures of acidic aqueous solution and organic solvent such as acetonitrile, ethanol, methanol and dimethyl sulfoxide (DMSO) were tested as sample solvents. For later-eluting analytes, the increase of sample solvent elution strength was responsible for the decrease of separation efficiency. Thus, sample solvents with weak elution strength could provide high separation efficiencies. For earlier-eluting analytes, the retention of organic sample solvents was the main factor affecting separation efficiency. Weakly retained solvents could provide high separation efficiency. In addition, an optimized approach was proposed to reduce the effect of organic sample solvent, in which low ionic solvent was employed as initial mobile phase in the gradient. At last, the analysis of impurities in hydrophobic drug berberine was performed. The results showed that using acidic aqueous methanol as sample solvents could provide high separation efficiency and good resolution (R > 1.5). 相似文献
100.
In this paper, we presented a novel, rapid and highly sensitive sensor for glutathione (GSH), cysteine (Cys) and histidine (His) based on the recovered fluorescence of the carbon quantum dots (CQDs)–Hg(II) system. The CQDs were synthesized by microwave-assisted approach in one pot according to our previous report. The fluorescence of CQDs could be quenched in the presence of Hg(II) due to the coordination occurring between Hg(II) and functional groups on the surface of CQDs. Subsequently, the fluorescence of the CQDs–Hg(II) system was recovered gradually with the addition of GSH, Cys or His due to their stronger affinity with Hg(II). A good linear relationship was obtained from 0.10 to 20 μmol L−1 for GSH, from 0.20 to 45 μmol L−1 for Cys and from 0.50 to 60 μmol L−1 for His, respectively. This method has been successfully applied to the trace detection of GSH, Cys or His in human serum samples with satisfactory results. The proposed method was simple in design and fast in operation, which demonstrated great potential in bio-sensing fields. 相似文献