Electrocatalytic oxidation of norepinephrine at a reduced C60-[dimethyl-(β-cyclodextrin)]2 and Nafion chemically modified electrode

The reduced C₆₀-[dimethyl-(β-cyclodextrin)]₂/Nafion chemically modified electrode is demonstrated to catalyze the electrochemical response of norepinephrine (NE) by cyclic voltammetry. A pair of well-defined redox waves were obtained and the calculated standard rate constant (k_s) is 4.4×10⁻³ cm s⁻¹ at this reduced CME, indicating that the reduced C₆₀-[dimethyl-(β-cyclodextrin)]₂ can act as promoter to the electron transfer of NE.     

整流装置滤除谐波的措施

对多相整流电路的高次谐波进行了分析，并指出其对节能工作及微机的集散系统的干扰，经过分析提出了消除谐波的措施，通过应用实例介绍了不同条件时可采取的不同消除办法。     

Bioassembled nanocircuits of Mo6S9-xIx nanowires for electrochemical immunodetection of estrone Hapten

We demonstrate a novel and highly sensitive electrochemical detection of estrone based on an immunosensor platform, composed of bioassembled nanocircuits of Mo 6S 9- x I x nanowires (MoSI NWs) covalently connected to anti-estrone antibodies. The one-step, label-free, and quantitative detection of estrone is realized by employing the [Ru(NH 3) 6] (3+/2+) redox ions to sense anti-estrone antibody and estrone interactions. The MoSI NWs/anti-estrone antibody nanocircuit architectures provide an amplification and conductive pathway for the specific electrochemical sensing of estrone hapten. A detection limit of 1.4 pg x mL (-1) was achieved in contrast to previous electrochemical techniques in which the sensitivity was limited to the nanomolar range.     

Electrochemical DNAzyme sensor for lead based on amplification of DNA-Au bio-bar codes

An electrochemical DNAzyme sensor for sensitive and selective detection of lead ion (Pb(2+)) has been developed, taking advantage of catalytic reactions of a DNAzyme upon its binding to Pb(2+) and the use of DNA-Au bio-bar codes to achieve signal enhancement. A specific DNAzyme for Pb(2+) is immobilized onto an Au electrode surface via a thiol-Au interaction. The DNAzyme hybridizes to a specially designed complementary substrate strand that has an overhang, which in turn hybridizes to the DNA-Au bio-bar code (short oligonucleotides attached to 13 nm gold nanoparticles). A redox mediator, Ru(NH3)6(3+), which can bind to the anionic phosphate of DNA through electrostatic interactions, serves as the electrochemical signal transducer. Upon binding of Pb(2+) to the DNAzyme, the DNAzyme catalyzes the hydrolytic cleavage of the substrate, resulting in the removal of the substrate strand along with the DNA bio-bar code and the bound Ru(NH3)6(3+) from the Au electrode surface. The release of Ru(NH3)6(3+) results in lower electrochemical signal of Ru(NH3)6(3+) confined on the electrode surface. Differential pulse voltammetry (DPV) signals of Ru(NH3)6(3+) provides quantitative measures of the concentrations of Pb(2+), with a linear calibration ranging from 5 nM to 0.1 microM. Because each nanoparticle carries a large number of DNA strands that bind to the signal transducer molecule Ru(NH3)6(3+), the use of DNA-Au bio-bar codes enhances the detection sensitivity by five times, enabling the detection of Pb(2+) at a very low level (1 nM). The DPV signal response of the DNAzyme sensor is negligible for other divalent metal ions, indicating that the sensor is highly selective for Pb(2+). Although this DNAzyme sensor is demonstrated for the detection of Pb(2+), it has the potential to serve as a general platform for design sensors for other small molecules and heavy metal ions.     

金属厚壁结构中深裂纹的重构方法研究

为了提高涡流方法检测厚壁结构中深裂纹的检测精度,使用三维涡流程序对涡流信号进行了仿真,通过分析传感器布置方案对检测信号及噪声的影响,提出了基于反面涡流检测信号的深裂纹重构策略,并开发了相应的逆问题反演程序,对重构策略的可行性进行了验证.数值仿真结果表明,所提出的基于反面涡流检测信号的深裂纹重构策略,可有效提高厚壁结构中深裂纹的重构精度,并可用于工程实践.     

Ferrocene-filled single-walled carbon nanotubes

Ferrocene molecules are successfully introduced into the inner hollow space of Single-walled carbon nanotubes (SWNTs) to get ferrocene-filled SWNTs (Fc@SWNTs). This nanohybrid material was carefully characterized by high resolution microscopy, FTIR spectrum, and Cyclic voltammetry (CV). This new material may not only act as air stable n-type field-effect transistors based on nanotubes, but it may also be employed as building blocks for various devices based on the redox activity of ferrocene. What’s more, upon high temperature annealing, the encapsulated ferrocene molecules will decompose and change into interior tubes, forming double-walled carbon nanotubes (DWNTs). This provides convincing evidence that ferrocene molecules are inserted into the hollow cavities SWNTs. This result also presented a controllable way to synthesize DWNTs.     

Electrochemistry of double-wall carbon nanotubes encapsulating C60 and their spectral characterization

Electrochemistry of double-wall carbon nanotubes (DWCNTs) encapsulating C₆₀ (C₆₀@DWCNT) have been studied by preparing a C₆₀@DWCNT modified electrode, and three pairs of reversible electro-reduction waves corresponding to electron transfer reactions of C₆₀ inside DWCNTs have been obtained in a mixed solvent of toluene and acetonitrile (4:1, v:v) containing tetrabutylammonium cation as supporting electrolyte, which indicates that DWCNTs act as molecular wires to allow electrical communication between the underlying electrode and the redox-active guest C₆₀. The influencing factors on the electrochemistry of C₆₀@DWCNT modified electrodes have been investigated. The results suggest that the voltammetric behavior of C₆₀@DWCNT is dependent on the nature of the supporting electrolyte and the solvent system. In addition, spectral characterization of the C₆₀@DWCNT modified electrodes before and after electrochemical scanning reveals interaction between C₆₀ and DWCNT and verifies the reduction of C₆₀ encapsulated in DWCNTs. C₆₀ molecules inside DWCNTs retains their redox activity, and can also act as an electron-transfer mediator to electrocatalyze the reduction of halohydrocarbon.     

独立电力系统电压源型LCL逆变器虚拟阻尼控制

在独立电力系统中,LCL逆变器作为电压源为电网提供稳定电压,其输出谐振是影响电力系统稳定性的重要因素之一。为了提高系统稳定性,对LCL逆变器输出谐振抑制方法进行了研究,在目前采用的前馈解耦双闭环控制系统的基础上进行改进,引入虚拟阻尼代替实际阻尼,通过有源控制,选取合理的采样点和反馈位置,得到一种基于滤波电容电压前馈的虚拟阻尼控制方法。理论分析和仿真验证表明:该方法避免了额外并联实际电阻所造成的系统损耗,同时有效降低了系统输出阻抗,提高了系统的稳定裕度。     

PSK1 coordinates glucose metabolism and utilization and regulates energy-metabolism oscillation in Saccharomyces cerevisiae

Energy-metabolism oscillations (EMO) are ultradian biological rhythms observed in in aerobic chemostat cultures of Saccharomyces cerevisiae. EMO regulates energy metabolism such as glucose, carbohydrate storage, O₂ uptake, and CO₂ production. PSK1 is a nutrient responsive protein kinase involved in regulation of glucose metabolism, sensory response to light, oxygen, and redox state. The aim of this investigation was to assess the function of PSK1 in regulation of EMO. The mRNA levels of PSK1 fluctuated in concert with EMO, and deletion of PSK1 resulted in unstable EMO with disappearance of the fluctuations and reduced amplitude, compared with the wild type. Furthermore, the mutant PSK1Δ showed downregulation of the synthesis and breakdown of glycogen with resultant decrease in glucose concentrations. The redox state represented by NADH also decreased in PSK1Δ compared with the wild type. These data suggest that PSK1 plays an important role in the regulation of energy metabolism and stabilizes ultradian biological rhythms. These results enhance our understanding of the mechanisms of biorhythms in the budding yeast.     

Topotactic Transformation of Single‐Crystalline Precursor Discs into Disc‐Like Bi2S3 Nanorod Networks

Hierarchical, two‐dimensional (2D), disc‐like networks consisting of crossed single‐crystalline Bi₂S₃ nanorods have been synthesized via a novel 2D‐template‐engaged topotactic transformation process, which involves the formation of intermediate BiOCl single‐crystalline discs and their subsequent chemical transformation into disc‐like Bi₂S₃ nanofabrics. The transformation process from (001)‐oriented BiOCl discs to disc‐like Bi₂S₃ nanorod networks has been followed by using scanning electron microscopy (SEM), transmission electron microscopy (TEM), electron diffraction (ED) and X‐ray diffraction (XRD), which revealed that the close matching between the lattice constants of the c‐axis for orthorhombic Bi₂S₃ and the a‐ or b‐axis for tetragonal BiOCl could be responsible for the preferential growth of [001]‐oriented Bi₂S₃ nanorods on the top faces of (001)‐oriented BiOCl discs along the two perpendicular [100] and [010] directions of BiOCl. The diameter of the Bi₂S₃ nanorods involved in the networks can be adjusted by changing the bismuth ion concentration in the reaction solution; moreover, an increase of the HCl concentration would prevent the formation of precursor BiOCl discs, leading to the formation of Bi₂S₃ nanostructures with varied morphologies. Charge–discharge curves and cyclic voltammograms of the obtained Bi₂S₃ nanostructures were measured to investigate their electrochemical hydrogen storage behaviors. It was found that the disc‐like Bi₂S₃ nanorod networks could electrochemically charge and discharge with a capacity of 162 mA h g^?1 at room temperature, indicating their potential applications in hydrogen storage, high‐energy batteries, and catalytic fields.