Xingyi Yuan  Yanji Tan  Xiaoping Wei  Jianping Li 《Luminescence》2017,32(7):1116-1122

A novel molecular imprinting electrochemiluminescence sensor for detecting chiral cinchonine molecules was developed with a molecularly imprinted polymer membrane on the surfaces of magnetic microspheres. Fe₃O₄@Au nanoparticles modified with 6‐mercapto‐beta‐cyclodextrin were used as a carrier, cinchonine as a template molecule, methacrylic acid as a functional monomer and N ,N ′‐methylenebisacrylamide as a cross‐linking agent. Cinchonine was specifically recognized by the 6‐mercapto‐beta‐cyclodextrin functional molecularly imprinted polymer and detected based on enhancement of the electrochemiluminescence intensity caused by the reaction of tertiary amino structures of cinchonine molecules with Ru(bpy)₃²⁺. Cinchonine concentrations of 1 × 10^?10 to 4 × 10^?7 mol/L showed a good linear relationship with changes of the electrochemiluminescence intensity, and the detection limit of the sensor was 3.13 × 10^?11 mol/L. The sensor has high sensitivity and selectivity, and is easy to renew. It was designed for detecting serum samples, with recovery rates of 98.2% to 107.6%.  相似文献   

    

J. Carrasco  M.J. Navarro  M. Santos  F.J. Gea 《The Annals of applied biology》2017,171(1):62-69

The fungicides chlorothalonil, metrafenone, prochloraz‐Mn, thiabendazole and thiophanate‐methyl were tested in vitro and in vivo for their effect on Cladobotryum mycophilum, the mycoparasite that causes cobweb disease in white button mushroom. In vitro experiments showed that metrafenone (EC₅₀= 0.025 mg L^?1) and prochloraz‐Mn (EC₅₀= 0.045 mg L^?1) were the most effective fungicides for inhibiting the mycelial growth of C. mycophilum. Selectivity indexes of the tested fungicides on both C. mycophilum and Agaricus bisporus indicated that metrafenone was also the most selective fungicide, while chlorothalonil was the most toxic fungicide against A. bisporus mycelium. The in vivo efficacy of fungicides for controlling cobweb was evaluated in three mushroom cropping trials, which were artificially inoculated with C. mycophilum (10⁶ conidia m^?2). Prochloraz‐Mn provided good control, although the surface colonised by cobweb reached 12% by the end of the crop cycles. None of the inoculated cropping trials treated with metrafenone showed any cobweb disease symptoms, and neither were any significant phytotoxic effects on mushroom yield recorded. These results indicated that metrafenone can be used as an alternative to prochloraz‐Mn in the control of cobweb disease.  相似文献   

    

Francesco Pietra 《化学与生物多样性》2017,14(11)

In this work, viable models of cysteine dioxygenase (CDO) and its complex with l ‐cysteine dianion were built for the first time, under strict adherence to the crystal structure from X‐ray diffraction studies, for all atom molecular dynamics (MD). Based on the CHARMM36 FF, the active site, featuring an octahedral dummy Fe(II) model, allowed us observing water exchange, which would have escaped attention with the more popular bonded models. Free dioxygen (O₂) and l ‐cysteine, added at the active site, could be observed being expelled toward the solvating medium under Random Accelerated Molecular Dynamics (RAMD) along major and minor pathways. Correspondingly, free dioxygen (O₂), added to the solvating medium, could be observed to follow the same above pathways in getting to the active site under unbiased MD. For the bulky l ‐cysteine, 600 ns of trajectory were insufficient for protein penetration, and the molecule was stuck at the protein borders. These models pave the way to free energy studies of ligand associations, devised to better clarify how this cardinal enzyme behaves in human metabolism.  相似文献   

    

Fei Wang  Liumin Suo  Yujia Liang  Chongyin Yang  Fudong Han  Tao Gao  Wei Sun  Chunsheng Wang 《Liver Transplantation》2017,7(8)

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Yunchao Li  Shun Wan  Gabriel M. Veith  Raymond R. Unocic  Mariappan Parans Paranthaman  Sheng Dai  Xiao‐Guang Sun 《Liver Transplantation》2017,7(4)

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Saravanan Kuppan  Alpesh Khushalchand Shukla  Daniel Membreno  Dennis Nordlund  Guoying Chen 《Liver Transplantation》2017,7(11)

Surface properties of cathode particles play important roles in the transport of ions and electrons and they may ultimately dominate cathode's performance and stability in lithium‐ion batteries. Through the use of carefully prepared Li_1.2Ni_0.13Mn_0.54Co_0.13O₂ crystal samples with six distinct morphologies, surface transition‐metal redox activities and crystal structural transformation are investigated as a function of surface area and surface crystalline orientation. Complementary depth‐profiled core‐level spectroscopy, namely, X‐ray absorption spectroscopy, electron energy loss spectroscopy, and atomic‐resolution scanning transmission electron microscopy, are applied in the study, presenting a fine example of combining advanced diagnostic techniques with a well‐defined model system of battery materials. The present study reports the following findings: (1) a thin layer of defective spinel with reduced transition metals, similar to what is reported on cycled conventional secondary particles in the literature, is found on pristine oxide surface even before cycling, and (2) surface crystal structure and chemical composition of both pristine and cycled particles are facet dependent. Oxide structural and cycling stabilities improve with maximum expression of surface facets stable against transition‐metal reduction. The intricate relationships among morphology, surface reactivity and structural transformation, electrochemical performance, and stability of the cathode materials are revealed.  相似文献   

    

Lihui Xu  Sidong Tu  Congheng Chen  Juan Zhao  Yuan Zhang  Ping Zhou 《Biopolymers》2016,105(2):100-107

The abnormal aggregation of amyloid proteins is reported to play a critical role in the etiology of neurodegenerative disorders. Studies have shown that excessive ferric irons are associated with the misfolding of amyloid proteins, and that (‐)‐epigallocatechin gallate (EGCG) is a good metallic ion chelator with inhibitory effect on the aggregation of amyloid proteins. EGCG has been thus considered as a potential drug candidate for the treatment of neurodegenerative diseases. However, the mechanism of action for EGCG in inhibition of aggregation of amyloid proteins is still remaining unclear. Silk fibroin (SF) shares similarities with amyloid proteins in some amino acid sequences and fibrillation kinetics. In this work, therefore, we used SF as a model of protein to investigate the effects of Fe(III) and EGCG on conformational transition by using turbidity assay, thioflavin T (ThT) fluorescence spectroscopy, Raman spectroscopy, and atomic force microscope (AFM). We demonstrated that low concentration of Fe(III) ions promoted the formation of β‐sheet conformers, while high concentration of Fe(III) ions inhibited further aggregation of SF. EGCG could significantly inhibit the conformational transition of SF when induced by Fe(III), and decrease the amount of β‐sheet conformers dose‐dependently. The findings provide important information regarding to EGCG as a potential agent for the prevention and treatment of neurodegenerative diseases. Fe(III) can accelerate the conformation transition of silk fibrion (SF) from random coil into β‐sheet, while (‐)‐epigallocatechin gallate (EGCG) inhibits Fe(III)‐induced β‐sheet aggregation of SF., 2016. © 2015 Wiley Periodicals, Inc. Biopolymers 105: 100–107, 2016  相似文献   

    

Zhenwen Cui  Zhihong Zhong  Yong Yang  Baofeng Wang  Yuhao Sun  Qingfang Sun  Guo‐yuan Yang  Liuguan Bian 《Journal of biochemical and molecular toxicology》2016,30(8):396-403

Free radical damage caused by ferrous iron is involved in the pathogenesis of secondary brain injury after intracerebral hemorrhage (ICH). NF‐E2‐related factor 2 (Nrf2), a major phase II gene regulator that binds to antioxidant response element, represents an important cellular cytoprotective mechanism against oxidative damage. We hypothesized that Nrf2 might protect astrocytes from damage by Fe²⁺. Therefore, we examined cytotoxicity in primary astrocytes induced by iron overload and evaluated the effects of Fe²⁺ on Nrf2 expression. The results demonstrated that 24‐h Fe²⁺ exposure exerted time‐ and concentration‐dependent cytotoxicity in astrocytes. Furthermore, Fe²⁺ exposure in astrocytes resulted in time‐ and concentration‐dependent increases in Nrf2 expression, which preceded Fe²⁺ toxicity. Nrf2‐specific siRNA further knocked down Nrf2 levels, resulting in greater Fe²⁺‐induced astrocyte cytotoxicity. These data indicate that induction of Nrf2 expression could serve as an adaptive self‐defense mechanism, although it is insufficient to completely protect primary astrocytes from Fe²⁺‐induced neurotoxicity.  相似文献   

    

Raju Kumar Chandrakar  R. N. Baghel  B. P. Chandra 《Luminescence》2016,31(2):317-322

ZnS:Mn nanoparticles were prepared by a chemical precipitation method and characterized by X‐ray diffraction (XRD), field emission gun scanning electron microscope (FEGSEM), and high resolution transmission electron microscopy (HRTEM). Capping agent (mercaptoethanol) concentrations used were 0 M, 0.005 M, 0.01 M, 0.015 M, 0.025 M, 0.040 M, and 0.060 M, and resulted in nanoparticles sizes of 2.98 nm, 2.9 nm, 2.8 nm, 2.7 nm, 2.61 nm, 2.2 nm and 2.1 nm, respectively. The thermoluminescence (TL) glow curve was recorded by heating the sample exposed to UV‐radiation, at a fixed heating rate 1°C sec^–1. The TL intensity initially increased with temperature, attained a peak value I_m for a particular temperature, and then decreased with further increase in temperature. The peak TL intensity increased with decreasing nanoparticle size, whereas the temperature corresponding to the peak TL intensity decreased slightly with reducing nanocrystal size. As a consequence of increase in surface‐to‐volume ratio and increased carrier recombination rates, the TL intensity increased with decreasing nanoparticle size. It was found that, whereas activation energy slightly decreased with decreasing nanoparticle size, the frequency factor decreased significantly with reduction in nanoparticle size. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

    

Le Thi Quynh  Chien Nguyen Van  Yugandhar Bitla  Jhih‐Wei Chen  Thi Hien Do  Wen‐Yen Tzeng  Sheng‐Chieh Liao  Kai‐An Tsai  Yi‐Chun Chen  Chun‐Lin Wu  Chih‐Huang Lai  Chih‐Wei Luo  Yung‐Jung Hsu  Ying‐Hao Chu 《Liver Transplantation》2016,6(18)

Self‐assembled vertical heterostructure with a high interface‐to‐volume ratio offers tremendous opportunities to realize intriguing properties and advanced modulation of functionalities. Here, a heterostructure composed of two visible‐light photocatalysts, BiFeO₃ (BFO) and ε‐Fe₂O₃ (ε‐FO), is designed to investigate its photoelectrochemical performance. The structural characterization of the BFO‐FO heterostructures confirms the phase separation with BFO nanopillars embedded in the ε‐FO matrix. The investigation of band structure of the heterojunction suggests the assistance of photoexcited carrier separation, leading to an enhanced photoelectrochemical performance. The insights into the charge separation are further revealed by means of ultrafast dynamics and electrochemical impedance spectroscopies. This work shows a delicate design of the self‐assembled vertical heteroepitaxy by taking advantage of the intimate contact between two phases that can lead to a tunable charge interaction, providing a new configuration for the optimization of photoelectrochemical cell.  相似文献