摘要：
Amine-modified magnetite (NH(2)-Fe(3)O(4))/reduced graphene oxide nanocomposite modified glassy carbon electrodes (NH(2)-Fe(3)O(4)/RGO/GCEs) were developed for the sensitive detection of dopamine (DA). The NH(2)-Fe(3)O(4)/RGO/GCEs were fabricated using a drop-casting method followed by an electrochemical reduction process. The surface morphologies, microstructure and chemical compositions of the NH(2)-Fe(3)O(4) nanoparticles (NPs), reduced graphene oxide (RGO) sheets and NH(2)-Fe(3)O(4)/RGO nanocomposites were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-Ray diffraction (XRD) and Fourier-transform infrared (FTIR) spectroscopy. The electrochemical behaviors of DA on the bare and modified GCEs were investigated in phosphate buffer solution (PBS) by cyclic voltammetry (CV). Compared with bare electrode and RGO/GCE, the oxidation peak current (ipa) on the NH(2)-Fe(3)O(4)/RGO/GCE increase significantly, owing to the synergistic effect between NH(2)-Fe(3)O(4) NPs and RGO sheets. The oxidation peak currents (ipa) increase linearly with the concentrations of DA in the range of 1 x 10(-8) mol/L - 1 x 10(-7) mol/L, 1 x 10(-7) mol/L - 1 x 10(-6) mol/L and 1 x 10(-6) mol/L - 1 x 10(-5) mol/L. The detection limit is (4.0 +/- 0.36) x10(-9) mol/L (S/N = 3). Moreover, the response peak currents of DA were hardly interfered with the coexistence of ascorbic acid (AA) and uric acid (UA). The proposed NH(2)-Fe(3)O(4)/RGO/GCE is successfully applied to the detection of dopamine hydrochloride injections with satisfactory results. Together with low cost, facile operation, good selectivity and high sensitivity, the NH(2)-Fe(3)O(4)/RGO/GCEs have tremendous prospects for the detection of DA in various real samples.
关键词：
Water quality;Water pollution;Surface water;Rivers;Economic analysis;Land use;Seasons;Cities
摘要：
Comprehensive understanding of the long-term trends and seasonality of water quality is important for controlling water pollution. This study focuses on spatio-temporal distributions, long-term trends, and seasonality of water quality in the Yangtze River basin using a combination of the seasonal Mann-Kendall test and time-series decomposition. The used weekly water quality data were from 17 environmental stations for the period January 2004 to December 2015. Results show gradual improvement in water quality during this period in the Yangtze River basin and greater improvement in the Uppermost Yangtze River basin. The larger cities, with high GDP and population density, experienced relatively higher pollution levels due to discharge of industrial and household wastewater. There are higher pollution levels in Xiang and Gan River basins, as indicated by higher NH4-N and CODMn concentrations measured at the stations within these basins. Significant trends in water quality were identified for the 2004–2015 period. Operations of the three Gorges Reservoir (TGR) enhanced pH fluctuations and possibly attenuated CODMn, and NH4-N transportation. Finally, seasonal cycles of varying strength were detected for time-series of pollutants in river discharge. Seasonal patterns in pH indicate that maxima appear in winter, and minima in summer, with the opposite true for CODMn. Accurate understanding of long-term trends and seasonality are necessary goals of water quality monitoring system efforts and the analysis methods described here provide essential information for effectively controlling water pollution.
摘要：
During past few years, some lightweight block ciphers have been proposed. These lightweight block ciphers take single encryption method that either uses Substitution-Permutation (SP) network structure or Feistel network structure to encrypt. In this paper, we have designed a different encryption method that takes both SP network structure and Feistel network structure to encrypt. Current SP network has a limitation that the encryption and decryption processes are dissimilar. To solve this problem, we have employed involution related properties of the nonlinear and linear components to modify SP network structure. The modified one enables the encryption and decryption program or circuit to work as the Feistel network structure. Additionally, we have implemented a MixRows in SP network structure. Then we instantiate these three novel ideas into the lightweight block cipher called SFN. We have carried out the security evaluation and the hardware and software experiments to it. The result shows that compared to other lightweight block ciphers, SFN has more advantages in terms of being immune to attacks. Also, SFN is not only compact in hardware environment but also efficient in software platforms.
摘要：
<![CDATA[<ce:abstract xmlns:ce="" xmlns="" xml:lang="en" id="abs0010" view="all" class="author"><ce:section-title id="sectitle0010">Abstract</ce:section-title><ce:abstract-sec id="abssec0010" view="all"><ce:simple-para id="abspara0010" view="all">In this work, the N doping together with Pd?Cu@Cu<ce:inf loc="post">2</ce:inf>O hybridization for graphene oxide was achieved by a combined process of hydrothermal treatment and chemical reduction, based on which a novel Pd?Cu@Cu<ce:inf loc="post">2</ce:inf>O cubes decorated N-doped reduced graphene oxide (Pd?Cu@Cu<ce:inf loc="post">2</ce:inf>O/N-RGO) hybrid was obtained. The synthesized Pd?Cu@Cu<ce:inf loc="post">2</ce:inf>O/N-RGO was detailedly characterized by various technologies. The results show that the low Pd loading Cu@Cu<ce:inf loc="post">2</ce:inf>O cubes with the sizes of 300–500?nm are well dispersed on N-RGO sheets, thereby avoiding the serious aggregation and maintaining a large electroactive surface area of the attained hybrid. Benefiting from the synergistic effect of the properties of Pd?Cu@Cu<ce:inf loc="post">2</ce:inf>O particles and N-RGO sheets, the Pd?Cu@Cu<ce:inf loc="post">2</ce:inf>O/N-RGO modified electrode exhibits remarkable electrocatalytic performance on the oxidation of tryptophan with the enhanced oxidation response and the lowered oxidation overpotential. Under the optimal conditions for the electrochemical detection of tryptophan, the constructed sensor displays a wide linear range (0.01–40.0?μM) and a low detection limit (1.9?nM), outperforming most of the reported hybrid-based sensors. The proposed sensor also features good selectivity, stability and reproducibility, which has been successfully applied for the detection of tryptophan in the urine and milk samples with satisfactory recoveries. All these results suggest that the Pd?Cu@Cu<ce:inf loc="post">2</ce:inf>O/N-RGO hybrid could be a promising and convenient material for the fabrication of high-performance electrochemical sensors.</ce:simple-para></ce:abstract-sec></ce:abstract><ce:abstract xmlns:ce="" xmlns="" class="graphical" id="abs0015" view="all"><ce:section-title id="sectitle0015">Graphical abstract</ce:section-title><ce:abstract-sec id="abssec0015" view="all"><ce:simple-para>Display Omitted</ce:simple-para></ce:abstract-sec></ce:abstract><ce:abstract xmlns:ce="" xmlns="" class="author-highlights" xml:lang="en" id="abs0020" view="all"><ce:section-title id="sectitle0020">Highlights</ce:section-title><ce:abstract-sec id="abssec0020" view="all"><ce:simple-para id="abspara0020" view="all"><ce:list id="ulist0010"><ce:list-item id="u0010"><ce:label>?</ce:label><ce:para id="p0010" view="all">The Pd?Cu@Cu<ce:inf loc="post">2</ce:inf>O/N-RGO hybrid was synthesized via a facile wet chemical route.</ce:para></ce:list-item><ce:list-item id="u0015"><ce:label>?</ce:label><ce:para id="p0015" view="all">An enhanced electrocatalytic property of the hybrid has been demonstrated.</ce:para></ce:list-item><ce:list-item id="u0020"><ce:label>?</ce:label><ce:para id="p0020" view="all">The constructed sensor displays super performances for the tryptophan detection.</ce:para></ce:list-item><ce:list-item id="u0025"><ce:label>?</ce:label><ce:para id="p0025" view="all">Advantages include excellent practicability with remarkable reliability.</ce:para></ce:list-item></ce:list></ce:simple-para></ce:abstract-sec></ce:abstract>]]>
作者：
Li Yu-Lin;Li Wei*;Li Chang-Hong*;Tan Xiong-Wen
期刊：
Chinese Journal of Structural Chemistry,2018年37(10):1651-1655 ISSN：0254-5861
通讯作者：
Li Wei;Li Chang-Hong
作者机构：
[Tan Xiong-Wen; Li Yu-Lin; Li Wei] Hengyang Normal Univ, Dept Chem & Mat Sci, Hengyang 421008, Peoples R China.;[Li Chang-Hong] Hunan Inst Technol, Dept Chem Engn, Hengyang 421002, Peoples R China.;[Li Wei] Key Lab Funct Met Organ Cpds Hunan Prov, Hengyang 421008, Peoples R China.
通讯机构：
[Li Wei; Li Chang-Hong] H;[Li Wei] K;Hengyang Normal Univ, Dept Chem & Mat Sci, Hengyang 421008, Peoples R China.;Hunan Inst Technol, Dept Chem Engn, Hengyang 421002, Peoples R China.;Key Lab Funct Met Organ Cpds Hunan Prov, Hengyang 421008, Peoples R China.
关键词：
heteronuclear;cobalt-sodium polymer;electrochemical and fluorescent properties
摘要：
A new cobalt-sodium coordination polymer vertical bar CoNa(C9H9N3O2S)2 center dot H2O vertical bar(2)center dot C2H3N center dot H2O (1) has been synthesized with cobalt chloride, 2-(2-hydroxy-3-methoxybenzylidene)hydrazinecarbothio amide (L) and sodium hydroxide. It crystallizes in the triclinic space group P (1) over bar, with a = 9.972(4), b = 10.923(4), c = 13.489(5) angstrom, alpha = 108.005(10), beta = 92.728(10), gamma = 93.16(1)degrees, V = 1392.0(9) angstrom(3), M-r = 1151.95, D-c = 1.374 g/cm(3), Z = 2, F(000) = 592, the final GOOF = 1.126, R = 0.1091 and wR = 0.2412. Each unit molecule consists of two cobalt ions and two sodium ions bridged by four 2-(2-hydroxy-3-methoxybenzylidene)hydrazinecarbothio amide anions. The coordination environment of Co ion is CoO2N2S2, giving a distorted octahedral geometry and the Na(1) ion is NaO4N, giving a distorted square pyramidal geometry. The results show that 1 shows one strong intense fluorescence emission wavelength of 429 nm with an excitation wavelength of 376 nm, and the electron transfer of 1 is irreversible in electrode reactions.
摘要：
A novel anionic organotin(IV) complex I {[p-ClC6H4CH2)Sn(H2O)(Cl)(2)OCOCH(O)CH(O)CO2Sn(H2O)(Cl)(2)(p-ClC6H4CH2)]center dot 2(HNEt3)} (1) was synthesized by the reaction of di(p-chlorobenzy)tin dichloride with the D-tartaric acid in 2:1 molar in the presence of an organic base triethylamine. The structure was characterized by elemental analysis, IR, TG, XRD and single-crystal X-ray diffraction. It crystallizes in triclinic, P-(1) over bar space group, with a = 0.7067(1), b = 1.9762(3), c = 2.2383(3) nm, alpha = 91.544(2)degrees, beta = 90.075(2)degrees, gamma = 90.110(2)degrees, V = 3.1247(7) nm(3), Z = 3, D-c = 1.621 g/cm(3), mu(MoK alpha) = 16.29 cm(-1), F(000) = 1530, R = 0.0394, wR = 0.1092, (Delta rho)(max) = 1224 and (Delta rho)(min) = -840 e/nm(3). The stabilities, orbital energies and composition characteristics of some frontier molecular orbitals of 1 have been carefully investigated with quantum chemistry calculation. In addition, the in vitro antitumor activity suggested that 1 had stronger inhibitory activity on H460, MCF7 than on A549.
摘要：
Finding a new derivative structure of FeSe-based superconductors with a high superconducting transition temperature ( Tc) is of great significance. Here, in this work, an organic-ion-[cetyltrimethyl ammonium ( CTA+)]-intercalated FeSe-based superconductor (CTA)0.3FeSe with Tc as high as 45 K is synthesized by an electrochemical intercalation method. The as-prepared (CTA)0.3FeSe has a hybrid crystal structure consisting of double layers of CTA+ and one layer of FeSe, which is consistent with a lateral-bilayer model. The superconductivity of (CTA)0.3FeSe is confirmed by magnetic susceptibility. Furthermore, a negative pressure effect on superconductivity dTc/dP=−5 K/GPa is observed. This is the first pure organic-ion-intercalated FeSe-based superconductor with a high Tc and high crystallinity. Our work offers a new method to modify the interface interaction between the FeSe layer and the intercalator, and sheds new light on finding new FeSe-based superconductors with higher Tc.
作者机构：
[Wang Junyun; Qiu Haihong] Hengyang Normal Univ, Hengyang 421008, Hunan, Peoples R China.
通讯机构：
[Wang Junyun] H;Hengyang Normal Univ, Hengyang 421008, Hunan, Peoples R China.
关键词：
Fuzzy decision tree;Internet plus Physical Education teaching;MOOC mode
摘要：
With the continuous development and application of the Internet, the traditional physical education teaching content of ordinary colleges and universities has become more and more serious, and it has not satisfied the students 'needs. Therefore, this paper put forward a research on the MOOC mode of P.E. teaching in the background of "Internet +" based on fuzzy decision tree algorithm, constructed the model of PE MOOC teaching, and introduced the fuzzy decision tree algorithm to optimize it. The results of teaching experiments show that the MOOC mode of physical education in colleges and universities based on fuzzy decision tree algorithm can effectively improve the quality and efficiency of PE teaching, stimulated students 'autonomous learning and improved students 'achievements in all aspects.
摘要：
Protection of entanglement from disturbance of the environment is an essential task in quantum information processing. We investigate the entanglement protection of a qubit-qubit system interacting with a phase decoherence reservoir by employing the weak measurement (WM) and quantum measurement reversal (QMR). We show explicitly that the quantum entanglement can be obviously protected by means of the proper WM and QMR. In particular, we found that there is a specific initial state parameter region, the entanglement protection ratio, which is determined only by the initial state parameter and independent of the form of the spectral density of the reservoir.
作者机构：
[Chen, Shaolin] Soochow Univ, Dept Math, Suzhou 215006, Jiangsu, Peoples R China.;[Chen, Shaolin] Hengyang Normal Univ, Coll Math & Stat, Hengyang 421008, Hunan, Peoples R China.;[Ponnusamy, Saminathan] ISI, Chennai Ctr, SETS, MGR Knowledge City, CIT Campus, Madras 600113, Tamil Nadu, India.
通讯机构：
[Chen, Shaolin] S;[Chen, Shaolin] H;Soochow Univ, Dept Math, Suzhou 215006, Jiangsu, Peoples R China.;Hengyang Normal Univ, Coll Math & Stat, Hengyang 421008, Hunan, Peoples R China.
作者机构：
[Yu, Jiangxi; Zhang, Fuxing; Mao, Fangfang; Wang, Deping; Zheng, Yanwen] Hengyang Normal Univ, Coll Chem & Mat Sci, Hengyang 421008, Hunan, Peoples R China.;[Yang, Min; Xia, Xiaohong] Hunan Univ, Coll Mat Sci & Engn, Changsha 410082, Hunan, Peoples R China.
通讯机构：
[Wang, Deping; Xia, Xiaohong] H;Hengyang Normal Univ, Coll Chem & Mat Sci, Hengyang 421008, Hunan, Peoples R China.;Hunan Univ, Coll Mat Sci & Engn, Changsha 410082, Hunan, Peoples R China.
摘要：
A room-temperature and PTC-free copper-catalyzed N-arylation of aliphatic amines in neat water has been developed. Using a combination of CuI and 6,7-dihydroquinolin-8(5H)-one oxime as the catalyst and KOH as the base, a wide range of aliphatic amines are arylated with various aryl and heteroaryl halides to give the corresponding products in up to 95% yield.
摘要：
Two complexes [Ag(bpy)(H2O)](Hbac) (1) and [Ag-2(bpy)(2)(H2O)(2)](pdc)(H2O)(5) (2) (H(2)bac = benzilic acid, bpy = 4,4 '-bypyridine, H(2)pdc = 2,6-pyridinedicarboxylic acid) have been synthesized and characterized by IR, element analysis, X-ray-single crystal diffraction and TGA. Crystal data for 1: Monoclinic, space group C2/c, alpha = 18.8192(5) a, b = 12.7131(5) a, c = 17.8373(8) a, beta = 95.745(4), V = 4246.1(3) a(3) and Z = 8; 2: Triclinic, space group, P-1, alpha = 8.132(5) a, b = 10.485(6) a, c = 18.026(10) a, alpha = 96.194(10), beta = 91.047(11), gamma = 105.866(10), V = 1468.0(15) a(3) and Z = 2. In complex 1, Ag(I) is coordinated by two discrete 4,4'-bpy ligands and one water molecule and Hbac(-) behaves as a counterpart anion. In the crystal, a 3D network was formed by hydrogen bonds and pi pi face-to-face interactions. In complex 2, Ag(I) is also coordinated by two discrete 4,4'-bpy ligands and one water molecule and pdc(2-) behaves as a counterpart anion, too. In the crystal, a similar 3D network was formed by hydrogen bonds and pi pi face-to-face interactions as well as that of complex 1. The luminescence properties of 1 and 2 have been investigated.
