摘要:
In this study, PM10 samples at four locations of Loudi, China were collected from January 2017 to March 2017 and December 2017 to February 2018 at first. Then, a new analytical strategy of second-order calibration based on the alternating trilinear decomposition (ATLD) coupled with gas chromatography-mass spectrometry (GC-MS) was firstly developed for quantitative analysis of seven polycyclic aromatic hydrocarbons (PAHs) in these samples. This strategy is more sensitive and efficient than traditional chromatography not only, but also it can resolve the problems of baseline drift and peaks overlapping in chromatographic analysis. Without the need for intricate pretreatment process and any derivation reactions, useful qualitative and quantitative information of seven PAHs was quickly extracted from the GC-MS-Sample data array by replacing chemical or physical separation with mathematical separation. In validation samples, the average recoveries of seven PAHs ranged from (96.7 +/- 4.8) % to (107.9 +/- 4.2) %, and the root-mean-square errors of prediction (RMSEPs) were within the range of 0.03-0.35 mu g mL(-1). The highest concentrations of individual PAHs in these samples were for phenanthrene (1.34 mu g mL(-1) in monitoring station), acenaphthylene (0.79 mu g mL(-1) in municipal government) and chrysene (0.53 mu g mL(-1) in monitoring station). Identified by component analysis, coal combustion and vehicle exhaust were the most possible sources of Loudi, China. These results demonstrated that the proposed method is characterised as a more precise, simple and promising analytical strategy to identify and quantify PAHs in actual aerosol.
摘要:
Nickel-based compounds have been regarded as potential sulfur carriers in Li-sulfur (Li-S) battery. However, the relationship between the anions in those compounds, which are crucial to the intrinsic properties, and their electrochemical performances remains unclear. Herein, nickel compounds with the same morphologies, i.e., Ni5P4, NiO, and NiS, grown on carbon cloths (noted as Ni(x)A(y)@CC (A = O, S, P)) have been rationally designed to act as sulfur hosts in Li-S batteries to investigate the compositional effects on their catalytic activities and chemical absorption abilities. Density functional theory (DFT) results demonstrate that such variations in electrochemical performance are attributed to the interaction between polysulfides (PSs) and nickel compounds, leading to different adsorption energies and interfacial states. Among them, Ni5P4@CC exhibits the best electrochemical performance, delivering capacities of 1349.5, 1020.4, 803.7, 656.7 mAh g(-1) at rates of 0.1, 0.5, 2, and 3C, respectively. Moreover, super stable cycling performance has been achieved at 1C and 3C by Ni5P4@CC-based electrode, showing an ultralow decay ratio of 0.0357% and 0.0173% per cycle for over 1000 and 2000 cycles, respectively. In contrast, NiS@CC and NiO@CC show 0.0796% and 0.0787% per cycle at the cycling test. (C) 2020 Elsevier Ltd. All rights reserved.
摘要:
The installation of a HCF2 group is a research area that has received increasing attention, and deoxydifluorination of aldehydes have served as an attractive protocol due to the wide availability of aldehydes. Herein we describe a Ph2S/Selectfluor-promoted deoxydifluorination of aldehydes under mild conditions. Compared with previous deoxydifluorination methods, which usually use hazardous reagents such as SF4, DAST and Deoxo-Fluor, this protocol is quite attractive because of the safe and convenient operations, and the use of easily available reagents. (C) 2021 Elsevier Ltd. All rights reserved.
摘要:
An esterification and amination of benzylic C-H bonds was developed by using 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) under metal- and iodide-free conditions. Both carboxylic acids and amines could be used as ideal coupling partners for the oxidative coupling reactions with various diarylmethanes. A close to equal amount of coupling reagents was enough to afford the product in good to high yields.
期刊:
Journal of Chromatography A,2020年1618:460905 ISSN:0021-9673
通讯作者:
Zhang, Xiao-Hua;Liu, Zhi
作者机构:
[Zhang, Xiao-Hua; Mu, Shu-Ting; Zhou, Qian; Liu, Pan-Hua; Zheng, Jing-Jing] Xuchang Univ, Food & Bioengn Coll, Key Lab Biomarker Based Rapid Detect Technol Food, Xuchang 461000, Peoples R China.;[Liu, Zhi] Zhejiang Acad Agr Sci, State Key Lab Managing Biot & Chem Threats Qual &, Inst Qual & Stand Agr Prod, Hangzhou 310021, Peoples R China.;[Qing, Xiang-Dong] Hunan City Univ, Coll Mat & Chem Engn, Hunan Prov Key Lab Dark Tea & Jin Hua, Yiyang 413049, Peoples R China.
通讯机构:
[Zhang, Xiao-Hua] X;[Liu, Zhi] Z;Xuchang Univ, Food & Bioengn Coll, Key Lab Biomarker Based Rapid Detect Technol Food, Xuchang 461000, Peoples R China.;Zhejiang Acad Agr Sci, State Key Lab Managing Biot & Chem Threats Qual &, Inst Qual & Stand Agr Prod, Hangzhou 310021, Peoples R China.
关键词:
Analysis of tea polyphenols;HPLC-DAD;Second-order advantage;Second-order multivariate methods;Time drift calibration
摘要:
Retention time shifts in second-order calibration-assisted chromatographic analysis seriously impact the modeling and quantitative accuracies in complex systems. In this work, three second-order methods, i.e. alternating trilinear decomposition (ATLD) algorithm, multivariate curve resolution-alternating least squares (MCR-ALS), alternating trilinear decomposition-assisted multivariate curve resolution (ATLD-MCR), were compared their performance to process liquid chromatographic data in the presence of retention time shifts and overlapped peaks. Firstly, the validation samples contain five tea polyphenols at three concentrate levels within the calibration ranges, helped to understand, visualize and interpret these features of three second-order multivariate methods. Secondly, experimental data were studied concerning the determination of polyphenols in Chinese tea samples by HPLC-DAD. The results showed that all three second-order multivariate methods realized satisfactory quantification for five targeted analytes in Pu-Er ripe tea samples and Green tea samples even with the interference of slight retention time shifts, average recoveries were 91.23% -113.16% for ATLD, 89.96%-115.96% for ATLD-MCR, 90.64%-117.60% for MCR-ALS, respectively. However, ATLD was disappointing in the case of larger time shifts (approx. 4.00 s and 6.40 s) occurring for the quantitative analysis of Black tea and Clinacanthus nutans tea, the average recoveries were just 67.33-84.05%. Relatively, MCR-ALS and ATLD-MCR were more significantly excellent, satisfactory results still can be obtained, the average recoveries for MCR-ALS and ATLD-MCR were in the range of 86.04-117.60% and 89.96-115.96%, respectively. (C) 2020 Elsevier B.V. All rights reserved.
摘要:
精炼渣是钢渣的一种,由于其CaO和MgO等碱性成分含量较高,可以用于捕获CO2.本文研究了水热预处理对提高富铝精炼渣CO2捕获容量的积极效果,分析了水热预处理时间、固液比、CO2流量、反应时间和温度等工艺条件对CO2捕获容量的影响,并结合XRD和FESEM分析阐明了水热预处理提高富铝精炼渣碳酸化程度的机理.研究结果表明:水热预处理精炼渣在常温常压条件下,最大的CO2捕获容量为0.126 g CO2/g渣,远远高于未经预处理渣的最大捕获容量0.042 g CO2/g渣;水热预处理使渣中的C12A7快速水化,生成薄片状产物,增大了渣与CO2反应的面积,抑制了渣颗粒表面碳酸钙膜的形成,增大了反应速度,从而提高了反应程度.
摘要:
Abstract: In this thesis, a series of polyimide (PI) composite films with different octaphenylcagesilsesqui-oxane (OPPOSS) contents were successfully prepared, in which 4,4’-diaminodiphenyl ether (ODA) and 3,3’,4,4’-dimethylketonetetracarboxylicdianhydride (BTDA) were used as raw materials. The morphology and properties of the materials were systematically studied. The results show that OPPOSS is well dispersed in PI matrix, and the water absorption of the material increases slightly with the increase of OPPOSS content, but it can be used in microelectronics industry. However, the dielectric constant (ε) of the composites decreases greatly with the increase of OPPOSS content. The ε of composites with 1% and 10% OPPOSS was 3.12 and 1.94, which was 12.4% and 45.5% lower than that of pure PI (3.56). When the content of OPPOSS is high, the material has ultra-low dielectric constant, which is expected to be used in nano electronic devices.#@#@#摘要: 本论文以4,4,-二氨基二苯醚(ODA)和3,3',4,4,-二甲酮四羧酸二酐(BTDA)为原料,成功制备了一系列不同八苯基笼型倍半硅氧烷(OPPOSS)含量的聚酰亚胺(PI)复合薄膜。对材料的形貌、性能进行了较为系统的研究,结果表明,OPPOSS在PI基体中得到了很好的分散,随着OPPOSS含量的增加,材料的吸水率略有增加,但仍能满足其在微电子行业中的应用。材料的介电常数随着OPPOSS含量的增加而得到有效降低。OPPOSS含量分别为1%和10%的PI介电常数为3.12和1.94,相比纯PI的介电常数(3.56)分别下降了12.4%和45.5%。当OPPOSS含量较高时,材料具有超低介电常数,可望在纳电子器件中得到应用。
作者机构:
[Liu, Jingxiao; Chen, Xiaohua; Tang, Qunli; Liu, Zheng; Chen, Xingzhu; Hao, Yisu; Hu, Aiping] Hunan Univ, Coll Mat Sci & Engn, Hunan Prov Key Lab Adv Carbon Mat & Appl Technol, Changsha 410082, Peoples R China.;[Liu, Zheng] Hunan City Univ, Coll Mat & Chem Engn, All Solid State Energy Storage Mat & Devices Key, Yiyang 413000, Peoples R China.
通讯机构:
[Liu, Z; Chen, XH; Liu, Zheng] H;Hunan Univ, Coll Mat Sci & Engn, Hunan Prov Key Lab Adv Carbon Mat & Appl Technol, Changsha 410082, Peoples R China.;Hunan City Univ, Coll Mat & Chem Engn, All Solid State Energy Storage Mat & Devices Key, Yiyang 413000, Peoples R China.
关键词:
Graphene-like porous carbon;Nitrogen-doped;Catalytic graphitized melamine-formaldehyde;Surface area specific capacitance
期刊:
Ecotoxicology and Environmental Safety,2020年190:110140- ISSN:0147-6513
通讯作者:
Xiao, Guqing
作者机构:
[Meng, Qiudong; Xiao, Guqing] Hunan City Univ, Coll Mat & Chem Engn, Yiyang 413000, Peoples R China.
通讯机构:
[Xiao, Guqing] H;Hunan City Univ, Coll Mat & Chem Engn, Yiyang 413000, Peoples R China.
关键词:
D151 resin preloaded with Fe3+;Salt resistance;Glyphosate;Coordination;Adsorption
摘要:
D151 resin preloaded with Fe(3+) [denoted as R-Fe(3+)] was to investigate R-Fe(3+) as an adsorbent for glyphosate from water in the presence high concentration of salt. The adsorption mechanism revealed the coordination of Fe(3+) inside R-Fe(3+) with O atoms of P-O and N atoms in glyphosate molecule. The adsorption capacity of glyphosate by R-Fe(3+) was much larger than that of D151 resin preloaded with Ni(2+), Cu(2+), Na(+) and H(+). Even in glyphosate solutions containing 16% NaCl, R-Fe(3+) showed the constant adsorption capacity of glyphosate. The result provided the fi rst evidence of R-Fe(3+) as a salt resistant adsorbent for glyphosate. The adsorption capacity of glyphosate was the maximum at pH 3.35. The adsorption thermodynamics showed that the adsorption of glyphosate by R-Fe(3+) was the ligand exchange of glyphosate and water. The maximum coordination ratio of glyphosate to Fe(3+) inside R-Fe(3+) was 1:1. The maximum adsorption capacity of glyphosate by R-Fe(3+) was up to 481.85 mg/g, which is much higher than that of other reported adsorbents in the presence 16% NaCl. 2 mol/L NaOH, 2 mol/L H2SO4 and 2 mol/L Fe2(SO4)3 could all be used to achieve over 97% regeneration of R-Fe(3+).