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:
For the comprehensive utilization of antimony smelting arsenic-alkali residue, there are some problems such as the incomplete separation and low recoveries of arsenic and alkali, and the formation of arsenic-alkali mixed salts with secondary pollution. In order to solve these problems, the leaching solution of arsenic-alkali residue (arsenic-alkali solution) was used as a raw material in this study, and a novel process of twice alkali recovery with CO2, deep alkali removal with H2SO4, As(V) reduction with SO2 and evaporation concentration to recover arsenic was proposed to dispose of the arsenic-alkali solution. The total recovery of alkali was 87.8% by twice alkali recovery from the arsenic-alkali solution. After washing and thermal decomposition of crude NaHCO3, the obtained Na2CO3 product can be used as the reagent of arsenic removal in the refining process of crude antimony. In the process of deep alkali removal, compared with the direct treatment, the consumption of H2SO4 after twice alkali recovery was markedly reduced from the arsenic-alkali solution, and also no mirabilite was precipitated. The total recovery of arsenic was 80.6% in the process of arsenic recovery, and the purity of As2O3 in arsenic trioxide product reached 95.2% after washing, which meets the third grade standard of arsenic trioxide (GB 26721–2011). This process realizes the efficient separation and recovery of arsenic and alkali from the arsenic-alkali solution, and also no arsenic-alkali mixed salts are produced.
摘要:
Satellite-based mapping has been proven to be an effective method to reveal the spatiotemporal variations of PM2.5 distributions. However, most satellite AOD (aerosol optical depth) statistical models suffer from unstable accuracy over long time spans. This study thus aims to propose an accurate and stable method for PM2.5 concentration estimations in time series. Specifically, a three-step residual variance constraint method (RVCM) is developed to simulate PM2.5 concentrations from January 2013 to December 2017 with the aid of AODs and other auxiliary data. Results show that the five-year fitting R-2 and cross-validation R-2 of RVCMs improved from 0.77 to 0.88 and 0.71 to 0.84, respectively, compared to those models without residual variance constraint (WO-RVCM). Additionally, RVCM demonstrated more stable performance on time series simulation of PM2.5 concentrations than WO-RVCM, with the yearly fitting R-2 of 0.89, 0.88,0.85, 0.87 and 0.88, and corresponding cross validation R-2 of 0.85, 0.84, 0.80, 0.82 and 0.83, respectively. Furthermore, accuracy verification of removed outliers in residual variance constraint modeling confirmed the credibility of RVCM in outliers' simulation compared to WO-RVCM models. Finally, RVCM-aided estimations of time series PM2.5 concentrations and associated premature deaths in the study area (east and southeast mainland China) revealed their total decrease rates were 35.21% and 21.57%, and excellent air quality days increased from 7% to 35%. These findings suggest that residual variance constraint is effective and could be a reliable solution to providing time series AOD-PM(2.5 )modeling with stable accuracy over long time spans. (C) 2019 Elsevier B.V. All rights reserved.
期刊:
Mathematical Inequalities and Applications,2020年23(1):77-93 ISSN:1331-4343
通讯作者:
Chu, Yu-Ming
作者机构:
[Yang, Zhen-Hang] Huzhou Univ, Dept Math, Huzhou 313000, Peoples R China.;[Qian, Wei-Mao] Huzhou Broadcast & TV Univ, Sch Continuing Educ, Huzhou 313000, Peoples R China.;[Zhang, Wen] Icahn Sch Med Mt Sinai, Friedman Brain Inst, New York, NY 10029 USA.;[Chu, Yu-Ming] Hunan City Univ, Coll Sci, Yiyang 413000, Peoples R China.;[Chu, Yu-Ming] Changsha Univ Sci & Technol, Sch Math & Stat, Changsha 410114, Peoples R China.
通讯机构:
[Chu, Yu-Ming] H;[Chu, Yu-Ming] C;Hunan City Univ, Coll Sci, Yiyang 413000, Peoples R China.;Changsha Univ Sci & Technol, Sch Math & Stat, Changsha 410114, Peoples R China.
关键词:
Gaussian hypergeometric function;complete elliptic integral;arithmetic-geometric mean
摘要:
In the article, we present several monotonicity properties and bounds for the complete elliptic integral of the first kind. As applications. we find sharp hounds for the arithmetic-geometric mean.
摘要:
ABSTRACT The influence of calcium bentonite addition on the compressive strength, efflorescence extent and drying shrinkage of fly-ash based geopolymer mortar was investigated. The results showed that appropriate amount (e.g. 15 wt%) of calcium bentonite addition favoured the enhancement of compressive strength mainly because its addition allowed the geopolymer to tolerate more water glass addition and therefore increased the Si/Al ratio of geopolymer. The maximum 28 d compressive strength of the geopolymer mortar with calcium bentonite addition reached 47.8 MPa, which was evidently larger than the maximum value of the specimen without calcium bentonite addition. Calcium bentonite addition was also beneficial for the reduction of drying shrinkage percentage of geopolymer mortar due to water adsorption and volume expansion properties of calcium bentonite. Moreover, calcium bentonite addition could reduce, even eliminate the efflorescence mainly due to Na+ adsorption by calcium bentonite through ion exchange. GRAPHICAL ABSTRACT
期刊:
IEEE INTERNET OF THINGS JOURNAL,2020年7(3):2247-2262 ISSN:2327-4662
通讯作者:
Qin, Hua
作者机构:
[Qin, Hua; Xiao, Xiang; Cao, Buwen; He, Jianxin; Chen, Weihong] Hunan City Univ, Coll Informat & Elect Engn, Yiyang 413000, Peoples R China.;[Peng, Yang] Univ Washington Bothell, Div Comp & Software Syst, Bothell, WA 98011 USA.
通讯机构:
[Qin, Hua] H;Hunan City Univ, Coll Informat & Elect Engn, Yiyang 413000, Peoples R China.
关键词:
Cross interface;energy-efficiency;gateway;Internet of Things (IoT)
摘要:
Featured with high bandwidth, high reliability, and native IP compatibility, WiFi has been recommended for a wide range of Internet-of-Things (IoT) applications. However, WiFi is inherently energy-hungry and it may impose high energy consumption on not only IoT devices but also gateways. To reduce gateway's WiFi energy consumption, many energy-efficient solutions for WiFi tethering services can be applied. However, these solutions mainly target the energy optimization of downlink data traffic in WLANs, and they are not suitable for the uplink data traffic of delivering massive IoT data from device to gateway (D2G), which is more common in IoT. When a gateway is powered by batteries, the high energy consumption caused by D2G communications may deplete the gateway quickly and renders the whole system dysfunctional as a result. Toward achieving energy-efficient D2G communications, we propose an innovative Green IoT Gateway (GIG) scheme, which aims at minimizing gateway energy consumption while ensuring the specific delay requirements of devices via cross-interface collaboration. Through utilizing the coexisting low-power ZigBee radios, GIG dynamically schedules the wakeup behaviors of high-power WiFi radios for energy-efficient and delay-bounded D2G communications. GIG has been implemented and evaluated in a prototype system, and the experiment results show that, under the moderate uplink data traffic and delay requirements, the energy consumption of GIG is 38.5% and 12.7% lower than those of a state-of-the-art WiFi tethering scheme and a simple version of the GIG scheme, respectively. Moreover, a great reduction of energy consumption at the device side can also be observed.
摘要:
Copper nanowires (CuNWs) are a key building block to facilitate carrier conduction across a broad range of nanodevices. For integration into nanoscale devices, manipulation and welding of these nanowires need to be overcome. Based on high energy density laser processing investigation, we report on innovative welding of single CuNWs to a silver film using a tightly focused laser beam combined with manipulation of CuNWs through the dielectrophoresis (DEP) method. Two types of lasers, femtosecond (FS) and continuous-wave (CW), were employed to analyze, improve, and control Cu-NW melting characteristics under high energy density irradiation. The FS laser welding of CuNWs resulted in a metallic joint with a low contact resistance suitable for functional electronic nanodevices. Computational simulations using the 1-D heat diffusion equation and finite difference method (FDM) were performed to gain an insight into metal-laser interactions for high performance welded contact development. Simulation studies on lasers established contrasting melting behavior of metal under laser irradiation. The device feasibility of CuNW based welded contacts was evaluated in terms of the electrical performance of a glucose sensor. It was possible to sense glucose concentration down to 10(-6) M, demonstrating a path towards integration of CuNWs into wearable, flexible nanoelectronic devices.