Selective activation of 1,2-dichloroethane for access to β-chloroethylarenes enabled by nickel-catalyzed suzuki-type couplings

The selective conversion of one inactive C(sp³)-Cl bond of 1,2-dichloroethane (DCE) into C(sp³)-C(sp²) linkages for access to β-chloroethylarenes is presented here. The key to achieve the required reactivity and chemoselectivity in this synthetic method was the utilization of nickel and combinatorial nitrogen ligands as catalytic system. Synthetic advantages of this coupling chemistry included the step-simplicities to β-chloroethylarenes, the mildness and effectiveness of coupling conditions, together with the convenience for allowing further functional group transformations of the retained homobenzylic C–Cl bonds.     

p‐Nitrophenyl Picolinate Cleavage by Unsymmetrical Bis‐Schiff Base Manganese(III) and Cobalt(II) Complexes with Aza‐Crown Ether or Morpholino Pendants

The unsymmetrical bis‐Schiff base manganese(III) and cobalt(II) complexes with either benzo‐10‐aza‐crown ether pendants (MnL¹Cl, MnL²Cl) or morpholino pendant (MnL³Cl, CoL³) have been employed as models for hydrolase by studying the kinetics of their hydrolysis reactions with p‐nitrophenyl picolinate (PNPP). A kinetic model of PNPP cleavage catalyzed by these complexes is proposed. The effects of complex structures and reaction temperature on the rate of PNPP hydrolysis have been examined. All four complexes exhibit high catalytic activity and the rate increases with pH under 25°C. The complexes of ligands containing a crown ether group exhibit higher catalytic activities than the non‐crown analogues. The catalytic activity of the complexes follows the order Mn(III)>Co(II) under the same ligands.     

Perturbed algorithms for solving nonlinear relaxed cocoercive operator equations with general A-monotone operators in Banach spaces

Based on the notion of general A-monotonicity, the new proximal mapping technique and Alber’s inequalities, a new class of nonlinear relaxed cocoercive operator equations with general A-monotone operators in Banach spaces is introduced and studied. Further, we also discuss the convergence and stability of a new perturbed iterative algorithm with errors for solving this class of nonlinear operator equations in Banach spaces. Since general A-monotonicity generalizes general H-monotonicity (and in turn, generalizes A-monotonicity, H-monotonicity and maximal monotonicity), our results improve and generalize the corresponding results of recent works.     

Multiparty Quantum Rotation Operation Sharing

International Journal of Theoretical Physics - Combining the ideas of quantum state sharing and multi-party quantum remote control, a novel four-participant quantum rotation operation sharing...     

碳量子点增强气液相化学发光检测二氧化碳北大核心CSCD

采用一步溶剂热法合成了能够发射绿色荧光的水溶性碳量子点(CDs),并对其进行了透射电子显微镜(TEM)、紫外可见光谱、荧光光谱以及红外谱图等一系列表征。基于该CDs增强的H_(2)O_(2)-KOH-CO_(2)气液相化学发光体系,利用自助研发的气液相化学发光检测仪实现了对CO_(2)气体的实时在线检测。研究了H_(2)O_(2)、KOH以及CDs浓度对发光强度的影响,结果表明当H_(2)O_(2)浓度为0.15 mol/L、KOH浓度为0.40 mol/L以及CDs溶液与KOH溶液体积比为1∶2时所测得的化学发光强度最大。在最优条件下,在0.196~49 mg/L范围内,CO_(2)浓度与发光强度呈现出良好的线性关系;计算得到二氧化碳的检测限为0.049 mg/L;重复检测11次1.96和4.56 mg/L的CO_(2)的相对标准偏差分别为1.46%和0.65%。采用该方法检测CO_(2)具有灵敏度高、选择性好、精密度高以及能够实现连续在线检测等优点。     

Study of Electrochemical Non-enzyme Glucose Sensor Based on Cu(Ⅱ)Co(Ⅱ) Bimetallic Carbon Nanosheets北大核心CSCD

CuCo-MOF nanofibers are synthesized by one-step solvent blending process at room temperature. Then CuCo-MOF nanofibers are used as the precursors,carbon nanosheets（Cu（Ⅱ）Co（Ⅱ）@C）uniformly loaded with nano-sized copper oxide and cobalt oxide are obtained by calcination at high temperature in air. Cu（Ⅱ）Co（Ⅱ）@C is modified on the glassy carbon electrode to directly catalyze glucose in alkaline solution. Because CuO and CoO are uniformly and firmly embedded on the carbon nanosheets,the agglomeration of catalyst is prevented,which greatly improves the specific surface area,and increases the catalytic active site. Meanwhile,due to the synergistic effect of copper and cobalt bimetals in the carbon nanosheet material,the enzyme free glucose sensor has excellent electrical conductivity and excellent catalytic performance. The detection range of the non-enzymatic electrochemical glucose sensors for glucose is 0. 03 µμmol/L~13. 6 mmol/L, the detection limit is 0. 01 µμmol/L（S/N=3）,and the sensitivity is 10. 56 mA·L/（cm2·mmol）. In addition, the non-enzyme sensor also has good anti-interference and high stability. © 2022, Science Press (China). All rights reserved.     

New estimate the bounds for the generalized Lorenz system

The bound of a chaotic system is important for chaos control, chaos synchronization, and other applications. In the present paper, the bounds of the generalized Lorenz system are studied, based on the Lyapunov function theory and the Lagrange multiplier method. We obtain a precise bound for the generalized Lorenz system. The rate of the trajectories is also obtained. Furthermore, we perform the numerical simulations. Numerical simulations are presented to show the effectiveness of the proposed scheme. Copyright © 2014 John Wiley & Sons, Ltd.     

Synthesis,characterization and spectroscopic investigation of a novel phenylhydrazone Schiff base with solvatochromism

A novel Schiff base of 4,5-diazafluorene-9-p-nitrophenylhydrazone (DAFND) has been synthesized and characterized. The crystal structures of DAFND and its analogue 4,5-diazafluorene-9-phenylhydrazone (DAFPD) were determined by single crystal X-ray diffraction method. X-ray analyses reveal that DAFPD comprise of a nonplanar molecule and all atoms of DAFND are essentially coplanar. The color of DAFND changes from brown to blue when heated, so called thermochromism and the spectroscopic properties of the two compounds are investigated by electronic absorption spectra, showing DAFND possess solvatochromism, while DAFPD does not have thermochromic and solvatochromic properties. The λ_max of DAFND within various pure solvents are different ranging from 370 nm in toluene to 614 nm in pyridine. The imaginable mechanisms of thermochromism and solvatochromism are proposed.     

Preferential binding specificity of silver cation to a single nucleobase over base pairs evaluated by abasic site-containing DNA

The binding specificity of silver cations to abasic (AP) site-containing DNA was electrochemically investigated by comparison with the fully matched DNA without the AP site. AP site-containing DNA is designed in a way that only the nucleotide opposite the AP site is variable to allow for coexistence of an unpaired nucleotide and a number of DNA base pairs. The surface of a gold electrode was modified by AP site-containing DNA duplex on which Ag⁺ binding specificity was evaluated. Electrochemical investigations on the AP-DNA-modified electrodes reveal that Ag⁺ preferentially associates to the unpaired nucleotides instead of the coexisted base pairs and shows sequence-dependant binding, especially stronger for purines than for pyrimidines. Additionally, the hydrogen bond pattern moieties of the unpaired nucleotides should be involved in Ag⁺ binding evidenced by a decrease of the redox signal when introducing a ligand with its hydrogen bond moiety complementary to the nucleotide deoxycytidine. This is the first attempt to make a comparison in one DNA molecule for metal ion binding to coexisted unpaired nucleotide and DNA base pairs. The present method demonstrates an easy way for investigating binding specificity of heavy metal ions to AP site in the presence of coexisted DNA base pairs.     

解析函数空间上的自伴加权复合算子

通过再生核函数刻画了Hardy空间,Bergman空间上自伴加权复合算子以及自伴等距加权复合算子,最后研究了单位球上的分式线性自同构,得到了一个充分条件。