Water effect on peroxy radical measurement by chemical amplification: Experimental determination and chemical mechanism

The water effect on peroxy radical measurement by chemical amplification was determined experimentally for HO2 and HO2 OH, respectively at room temperature (298±2) K and atmospheric pressure (1×105 Pa). No significant difference in water effect was observed with the type of radicals. A theoretical study of the reaction of HO2·H2O adduct with NO was performed using density functional theory at CCSD(T)/6-311 G(2d, 2p)//B3LYP/6-311 G(2d, 2p) level of theory. It was found that the primary reaction channel for the reaction is HO2·H2O NO→HNO3 H2O (R4a). On the basis of the theoretical study, the rate constant for (R4a) was calculated using Polyrate Version 8.02 program. The fitted Arrenhnius equation for (R4a) is k = 5.49×107 T 1.03exp(?14798/T) between 200 and 2000 K. A chemical model incorporated with (R4a) was used to simulate the water effect. The water effect curve obtained by the model is in accordance with that of the experiment, suggesting that the water effect is probably caused mainly by (R4a).     

A novel copper(II) complex constructed with mixed ligands of biphenyl-4,4′-dicarboxylic acid (H2bpdc) and dipyrido[3,2-d:2′,3′-f]quinoxaline (Dpq): Synthesis,structure, electrochemistry and electrocatalysis

A novel metal–organic framework [Cu₂(bpdc)₂(Dpq)₂(H₂O)]·H₂O (1) has been obtained from hydrothermal reaction of copper chloride with the mixed ligands [biphenyl-4,4′-dicarboxylic acid (H₂bpdc) and dipyrido[3,2-d:2′,3′-f]quinoxaline (Dpq)], and structurally characterized by elemental analysis, IR, TG and single-crystal X-ray diffraction analysis. The unique feature is that there simultaneously exist two kinds of one-dimensional (1-D) zigzag polymeric chains in complex 1. Moreover, the 1-D polymeric chains are ultimately packed into a three-dimensional (3-D) supramolecular framework through two different hydrogen bonding interactions. The adjacent different chains are linked by C–H?O hydrogen bonding interactions, and the same kind chains are further connected through C–H?π stacking interactions. Additionally, the complex 1 was used as solid bulk-modifier to fabricate renewable carbon paste electrode (Cu-CPE) by the direct mixing method. The electrochemical behavior and electrocatalysis of Cu-CPE have been studied in detail. The results indicate that Cu-CPE give one-electron quasi-reversible redox waves in potential range of 400 to ?300 mV due to the metal copper ion Cu(II)/Cu(I). The Cu-CPE showed good electrocatalytic activity toward the reduction of the bromate, nitrite and hydrogen peroxide. The electrocatalytic reduction peak currents of KBrO₃, KNO₂ and H₂O₂ showed a linear dependence on their concentrations. All of the results revealed that the Cu-CPE had a good reproducibility, remarkable long-term stability and especially good surface renewability by simple mechanical polishing in the event of surface fouling, which is important for practical application.     

Spatial confinement tuning of quenched disorder effects and enhanced magnetoresistance in manganite nanowires

Complex oxides have rich functionalities and advantages for future technologies.In many systems,quenched disorder often holds the key to determine their physical properties,and these properties can be further tuned by chemical doping.However,understanding the role of quenched disorder is complicated because chemical doping simultaneously alters other physical variables such as local lattice distortions and electronic and magnetic environments.Here,we show that spatial confinement is an effective approach to tuning the level of quenched disorder in a complex-oxide system while leaving other physical variables largely undisturbed.Through the confinement of a manganite system down to quasi-one-dimensional nanowires,we observed that the nature of its metal-insulator phase transition exhibits a crossover from a discontinuous to a continuous characteristic,in close accordance with quenched disorder theories.We argue that the quenched disorder,finite size,and surface effects all contribute to our experimental observations.Noticeably,with reduced nanowire width,the magnetoresistance shows substantial enhancement at low temperatures.Our findings offer new insight into experimentally tuning the quenched disorder effect to achieve novel functionalities at reduced dimensions.     

荧光小分子2-氨基-5,6,7-三甲基-1,8-萘啶识别dsDNA中胞嘧啶凸出

双链DNA（dsDNA）中单碱基凸出结构（bulge structure）具有重要生物学意义,这种结构也是DNA靶向药物的目标部位之一.荧光小分子2-氨基-5,6,7-三甲基-1,8-萘啶（ATMND）能够通过氢键识别胞嘧啶（cytosine）,因而对dsDNA中凸出的胞嘧啶表现出明显的特异性结合.与其余三种凸出的碱基相比,ATMND与凸出部位胞嘧啶的结合伴随着ATMND荧光的明显猝灭,因而可以用于胞嘧啶凸出结构的识别.利用解旋温度测量、荧光、圆二色光谱对ATMND和存在胞嘧啶凸出结构的dsDNA相互作用进行了研究.荧光滴定结果表明ATMND和dsDNA中凸出部位未配对的胞嘧啶的结合常数K11=4.8×105M？1.通过对含胞嘧啶凸出结构的dsDNA与ATMND结合前后的解旋温度曲线进行解析,发现胞嘧啶凸出结构相邻碱基对凸出的胞嘧啶与ATMND的结合有较大的影响.荧光测量结果也表明ATMND荧光的猝灭效率与凸出结构相邻碱基的类型有关,当相邻碱基为鸟嘌呤（guanine,G）时,荧光猝灭效率最高.基于dsDNA中凸出的碱基对ATMND荧光猝灭效率存在明显差异这一现象,设计了探针DNA实现了乳腺癌相关基因（PGR gene rs3740753）中单核苷酸多态性（G/C变异）的荧光分型.     

q移动差分方程亚纯解的一些性质（英文）

主要讨论了q移动差分方程零级亚纯解的一些性质,所得结果推广及改进了先前陈宗煊和郑秀敏,Korhonen等人的结果.     

Effect of inorganic positive ions on the adsorption of surfactant Triton X-100 at quartz/solution interface

The electrode-separated piezoelectric sensor (ESPS), an improved setup of quartz crystal microbalance (QCM), has been employed to investigate the adsorption behavior of nonionic surfactant Triton X-100 at the hydrophilic quartz-solution interface in mineralized water medium in situ, which contained CaCl2 0.01 mol·L?1, MgCl2 0.01 mol·L?1, NaCl 0.35 mol·L?1. In a large scale of surfactant concentration, the effects of Ca2 , Mg2 and Na on the adsorption isotherm and kinetics are obviously different. In aque-ous solution containing NaCl only, adsorption of Triton X-100 on quartz-solution interface is promoted, both adsorption rate and adsorption amount increase. While in mineralized water medium, multivalent positive ions Ca2 and Mg2 are firmly adsorbed on quartz-solution interface, result in the increasing of adsorption rate and adsorption amount at low concentration of surfactant and the peculiar desorption of surfactant at high concentration of Triton X-100. The results got by solution depletion method are in good agreement with which obtained by ESPS. The "bridge" and "separate" effect of inorganic positive ions on the adsorption and desorption mechanism of Triton X-100 at the quartz- solution interface is discussed with molecular dynamics simulations (MD), flame atomic absorption spectrometry (FAAS) and atomic force microscopy (AFM) methods.     

Structural properties of hydroxyl-substituted alkyl benzenesulfonates at the water/vapor and water/decane interfaces

Molecular dynamics simulations have been performed to investigate the structural properties of hydroxyl-substituted alkyl benzenesulfonate monolayers formed at the water/vapor and water/decane interfaces.We report a detailed study of the interfacial properties—liquid density profile,hydrogen bond structure,surfactant aggregate structure and order parameter—of the novel anionic surfactant,sodium 2-hydroxy-3-decyl-5-octylbenzenesulfonate(C10C8OHphSO3Na).Simulation results show that:with increasing number of s...     

可溶性鸟苷酸环化酶介导NO信号转导的结构基础及其分子机制研究

可溶性鸟苷酸环化酶(sGC)是NO信号转导通路中的核心金属酶,是NO的敏感器和受体.sGC含有?和?两个亚基,每个亚基分别具有3个结构域,包括血红素结构域、中心结构域和催化结构域,两个亚基的血红素结构域共享有一个血红素,NO结合到sGC的血红素后,激活sGC,催化其底物GTP转化为二级信号分子cGMP,开启PKG信号通路,导致血管舒张.NO信号转导通路异常将导致多种疾病的发生,如多种心血管疾病、肺动脉高血压、心力衰竭及神经退行性疾病等.近20年来,关于sGC的结构、功能、激活机制及其在生理与病理中的作用有了很多进展.本文重点对sGC的结构、功能及其活化/失活机制研究进展进行综述.     

Substituent groups from aromatic dicarboxylates modulated structural diversification in the assembly of Co(II) complexes based on the bis-pyridyl-bis-amide ligands

Four coordination polymers based on two bis-pyridyl-bis-amide ligands and three aromatic dicarboxylates with different substituent groups, namely, [Co(3-bpcb) 1.5 (NPH)(H2O)]·4H2O (1), [Co(3-bpcb)(NIPH)] (2), [Co(3-bpcb)0.5 (5-H2 AIP)]·2H2O (3), [Co(3-bpcd) 0.5 (5-H2 AIP)(H2O)]·2H2O (4) [3-bpcb = N,N′-bis(3-pyridinecarboxamide)-1,4-benzene, 3-bpcd = N,N′-bis(3- pyridine)cyclohexane-1,4-dicarboxamide, H2 NPH = 3-nitrophthalic acid, H2 NIPH = 5-nitroisophthalic acid, 5-H4 AIP = 5-aminoisophthalic acid] have been synthetized under hydrothermal conditions. Complex 1 displays a one dimensional (1D) chain based on the binuclear [Co2 (NPH)2 ] units and 3-bpcb ligands, which is extended into a three dimensional (3D) supramolecular framework through hydrogen bonding and - stacking interactions. In complex 2, the (3,5)-connected two dimensional (2D) layers are constructed from 1D Co-NIPH chains and bidentate-bridging 3-bpcb ligands. Complex 3 is a 2D double layer based on Co-5-H2 AIP 2D layers and 3-bpcb pillars. Complex 4 also displays a 2D network, which is constructed from the Co-5-H2AIP 1D double chains and 3-bpcd ligands. Finally, complexes 2-4 are extended into 3D supramolecular frameworks by hydrogen bonding or - stacking interactions. The substituent groups of dicarboxylates play an important role in the assembly and structures of the title complexes. In addition, the fluorescent properties of complexes 1-4 and the electrochemical behaviors of 3 and 4 at room temperature have been investigated.