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991.
Simultaneous preconcentration of polar and non‐polar organophosphorus pesticides from water samples by using a new sorbent based on mesoporous silica
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Zahra Soutoudehnia Korrani Wan Aini Wan Ibrahim Hamid Rashidi Nodeh Mohd Marsin Sanagi 《Journal of separation science》2016,39(6):1144-1151
A new mesoporous silica based on the sol–gel material cyanopropyltriethoxysilane (CNPrTEOS) was successfully synthesized by the hydrolysis and condensation of CNPrTEOS in the presence of ammonium solution as catalyst and methanol as solvent. It was used as a solid‐phase extraction sorbent for the simultaneous extraction of three organophosphorus pesticides, namely, polar dicrotophos and non‐polar diazinon and chlorpyrifos. Analysis was performed using high‐performance liquid chromatography with UV detection. CNPrTEOS was characterized by FTIR spectroscopy, field‐emission scanning electron microscopy and nitrogen gas adsorption. The surface area and average pore diameter of the optimum sol–gel CNPrTEOS are 379 m2/g and 4.7 nm (mesoporous), respectively. The proposed solid‐phase extraction based on CNPrTEOS exhibited good linearity in the range of 0.8–100 μg/L, satisfactory precision (1.15–3.82%), high enrichment factor (800) and low limit of detection (0.072–0.091 μg/L). The limits of detection obtained using the proposed solid‐phase extraction method are well below the maximum residue limit set by European Union and are also lower (13.6–48.5×) than that obtained by using a commercial CN‐SPE cartridge (0.98–4.41 μg/L). The new mesoporous sol–gel CNPrTEOS showed promising alternative as SPE sorbent material for the simultaneous extraction of polar and non‐polar organophosphorus pesticides. 相似文献
992.
Zongming Guo Linfeng Mei Fangshu Wan 《NoDEA : Nonlinear Differential Equations and Applications》2016,23(6):59
We obtain non-radial bifurcation from radial solutions of a semilinear elliptic equation in expanding annuli of \(\mathbb {R}^N\). To obtain the main results, we use a blow-up argument via the Morse index of the regular entire solutions of the equation The main results of this paper can be seen as applications of the properties of regular entire solutions of (0.1).
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$$\begin{aligned} -\Delta u=\lambda u^p \quad \text {in}\quad \mathbb {R}^N. \end{aligned}$$
(0.1)
993.
Ultrafast Photogenerated Hole Extraction/Transport Behavior in a CH3NH3PbI3/Carbon Nanocomposite and Its Application in a Metal‐Electrode‐Free Solar Cell
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Tao Ye Xi Jiang Dongyang Wan Xingzhi Wang Dr. Jun Xing Prof. Thirumalai Venkatesan Prof. Qihua Xiong Prof. Seeram Ramakrishna 《Chemphyschem》2016,17(24):4102-4109
Aligned and flexible electrospun carbon nanomaterials are used to synthesize carbon/perovskite nanocomposites. The free‐electron diffusion length in the CH3NH3PbI3 phase of the CH3NH3PbI3/carbon nanocomposite is almost twice that of bare CH3NH3PbI3, and nearly 95 % of the photogenerated free holes can be injected from the CH3NH3PbI3 phase into the carbon nanomaterial. The exciton binding energy of the composite is estimated to be 23 meV by utilizing temperature‐dependent optical absorption spectroscopy. The calculated free carriers increase with increasing total photoexcitation density, and this broadens the potential of this material for a broad range of optoelectronics applications. A metal‐electrode‐free perovskite solar cell (power conversion efficiency: 13.0 %) is fabricated with this perovskite/carbon composite, which shows great potential for the fabrication of efficient, large‐scale, low‐cost, and metal‐electrode‐free perovskite solar cells. 相似文献
994.
Zhen-Jie Li Xi Zheng Chun-Ping Wan Le Cai Ying Li Lin Huang 《Natural product research》2016,30(10):1136-1143
The branches and leaves of Pyrus pashia are used to cure abdominal pain and diarrhoea in Chinese folk medicine. A new phenilic compound, 4-O-β-d-glucopyranosylbenzyl-benzoate ester (1), along with 21 known ones (2–22) were isolated from the branches and leaves of this plant. Compounds 2 and 3 displayed remarkable antioxidant activities against 1,1-diphenyl-2-picrylhydrazyl radical (IC50 = 13.26 ± 0.04 μM, 13.28 ± 0.11 μM, respectively), which were at the same grade as positive control rutin. The caffeoyl group in compounds 2 and 3 was supposed to play an important role in the antioxidant activities. 相似文献
995.
Single machine SLK/DIF due window assignment problem with job-dependent linear deterioration effects
We consider single machine scheduling problems with deteriorating jobs and SLK/DIF due window assignment, where the deteriorating rates of jobs are assumed to be job-dependent. We consider two different objectives under SLK and DIF due window assignment, respectively. The first objective is to minimise total costs of earliness, tardiness, due window location and due window size, while the second objective is to minimise a cost function that includes number of early jobs, number of tardy jobs and the costs for due window location and due window size. We study the optimality properties for all problems and develop algorithms for solving these problems in polynomial time. 相似文献
996.
Liquid chromatography with mass spectrometry and NMR spectroscopy based discovery of cytotoxic principles from Daphne tangutica Maxim 总被引:1,自引:0,他引:1
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Xinzhou Yang Mi Huang Sijian Zheng Xinhua Ma Dingrong Wan Yunjiang Feng 《Journal of separation science》2016,39(11):2179-2187
An ethyl acetate extract from the barks of the ethnic Chinese medicine Daphne tangutica Maxim. exhibited antihepatocellular carcinoma activity against HepG2 and Hep3B cell lines. By using high‐performance liquid chromatography based activity profiling in combination with offline liquid chromatography with mass spectrometry and NMR analysis, we rapidly identified ten major components of the extract, including seven active principles, coumarins ( 1–4 ) and biscoumarins ( 7, 8, 10 ), along with three inactive flavonoids ( 5, 6, 9 ). This study demonstrated that our combined protocol can be used as an important strategy for chemical profiling, dereplication as well as the identification of bioactive compounds from herbal medicines. 相似文献
997.
Pengjuan Wang Ying Wan Aldalbahi Ali Shengyuan Deng Yan Su Chunhai Fan Shulin Yang 《中国科学:化学(英文版)》2016,59(2):237-242
Organophosphorous pesticide(OP) contamination has serious adverse effects on human health and the environment. Due to the toxicity of OPs and the threat presented by their accidental or intentional release in populated areas, the determination and monitoring of these OPs in food products and environment is of great importance. OPs are present in very small quantities and therefore, methods for their detection need to be highly sensitive and selective. Here, we aimed to develop a simple and selective aptamer-based colorimetric assay for the detection of omethoate, which is one of the commonly used OPs. The principle of the assay is that single-stranded DNA(ss DNA)-wrapped gold nanoparticles(Au NPs) are resistant to salt-induced aggregation. By employing an "artificial antibody" organophosphorous pesticide-binding aptamer(OBA) as the recognition element, aptamer-wrapped Au NPs(Au-apta) show high selectivity towards omethoate, resulting in the disconnection of aptamers from Au NPs and the aggregation of Au NPs. As there is a significant color change from the interparticle plasmon coupling during the aggregation of Au NPs, the established assay showed good linearity between 0.1 and 10 μmol/L, with a low detection limit of 0.1 μmol/L. Other OPs such as profenofos, phorate, and isocarbophos would not interfere with the detection of omethoate despite having similar structures. Thus, the colorimetric method shows potential for use in the detection of omethoate in real soil samples. 相似文献
998.
l-Tryptophan-capped carbon quantum dots (l-CQDs) were facilely synthesized through “green” methodology, and the obtained material was utilized as a sensitive and selective fluorescence sensor for mercury ion (Hg2+) in pure aqueous solutions. Carboxyl-functionalized CQDs were first green synthesized by a one-step hydrothermal route, and l-tryptophan was then attached to CQDs via direct surface condensation reaction in aqueous solution at room temperature. The as-synthesized l-CQDs had an average size of ca. 5 nm with a good dispersity in water, and exhibited a favorable selectivity for Hg2+ ions over a range of other common metal cations in aqueous solution (10 mM PBS buffer, pH 6.0). Upon the addition of Hg2+, a complete fluorescence quenching (ON–OFF switching) of l-CQDs was evident from the fluorescence titration experiment, and the fluorescence detection limit of Hg2+ was calculated to be 11 nM, which indicated that the obtained environmentally friendly l-CQDs had sensitive detection capacity for Hg2+ in aqueous solution. 相似文献
999.
本文以aug-cc-pv5Z为基组, 采用考虑Davidson修正的多参考组态相互作用方法(MRCI+Q)得到了GeS分子基态(X1Σ+)和5个低激发态(11Σ, 11Δ, A1Π, 15Σ+, 25Σ+)的势能曲线. 计算结果表明: 25Σ+态为排斥态, 其余5个态为束缚态; 6个态有着共同的离解通道, 离解极限均为Ge(3P)+S(3P). 利用计算得到的势能曲线得了X1Σ+, 11Σ-, 11Δ, A1Π和15Σ+态的垂直跃迁能Te, 平衡键长Re, 离解能De, 谐振频率ωe, 非谐性常数ωexe及平衡位置的电偶极矩. X1Σ+态的Re 为2.034 Å, De 为5.728 eV, ωe为571.73 cm-1, ωexe为1.6816 cm-1, 平衡位置的电偶极矩为1.9593 Debye. 激发态11Σ, 11Δ, A1Π, 15Σ+的Te 依次为25904.81, 26209.22, 32601.19, 43770.26 cm-1; Re依次为2.313, 2.322, 2.188, 2.8790 Å; De依次为2.524, 2.487, 1.694, 0.3036 eV, ωe依次为358.90, 353.08, 376.32, 134.96 cm-1; ωexe依次为1.2421, 1.2151, 1.6608, 1.9095 cm-1; 平衡位置的电偶极矩依次为1.3178, 1.4719, 1.5917, -1.9785 Debye. 通过求解核运动的薛定谔方程得到了J=0时X1Σ+, 11Σ-, 11Δ, A1Π和15Σ+态前30个振动态的振动能级Gv和分子常数Bv, 得到的结果和已有的实验值及其他理论值符合较好. 相似文献
1000.
钒合金作为聚变堆候选材料, 其辐照损伤行为一直是关注的重点. 研究辐照时形成的位错环的性质, 其意义在于揭示纯钒中辐照空洞的长大机理. 这种机理表现为不同类型位错环对点缺陷吸收的偏压不同, 从而影响金属的辐照肿胀. 本文利用加速器对纯钒薄膜样品进行氢离子辐照, 然后, 利用透射电镜的inside-outside方法分析氢离子辐照所形成的位错环的类型. 结果表明, 在氢离子辐照纯钒中没有发现柏氏矢量b=<110>的位错环, 只有柏氏矢量b=1/2<111>和b=<110>的位错环, 这两种位错环的惯性面处于{110}-{112}之间. 能确定性质的位错环全部为间隙型位错环, 未发现空位型位错环. 相似文献