二阶椭圆问题的混合元方向交替法

本文研究了一般的二阶椭圆问题的混合元方向交替法，给出了两种迭代格式即Uzawa格式和Arrow－Hurwitz格式，并就系数是常数的情形给出了谱分析．本文的结果对油藏模拟有一定的理论和实际意义．     

Attenuated total reflection method for measurements of optical properties of metallic films bordering anisotropic dielectrics

Thin-film assemblies of magnesium fluoride/aluminium/BK7-glass (MgF₂/Al/BK7) and rutile/aluminium/BK7-glass (TiO₂/Al/BK7) are experimentally studied, both by a direct coupling of evanescent waves and by a coupling of guided waves into surface plasmon waves (SPWs). Anisotropic effects of the prism coupler as well as the MgF₂ and the TiO₂ films on the phase-matching condition are examined theoretically and experimentally. The dielectric function of the Al films is recovered from SPW experiments with an uncertainty <10%.     

From n-alkane to polyacetylene on Cu (110): Linkage modulation in chain growth

Direct coupling or transformation of inert alkanes based on the selective C–H activation is of great importance for both chemistry and chemical engineering. Here, we report the coupling of polyenes that are transformed from n-dotriacontane (n-C₃₂H₆₆)through on-surface cascade dehydrogenation on Cu (110) surface, leading to the formation of polyacetylene (PA). Three distinct linkages have been resolved by scanning tunneling microscope (STM) and noncontact atomic force micros...     

微通道换热器流动和传热特性的研究

通过对微通道换热器流动和传热特性的研究,设计了实验方案并建立了相应的实验装置,结合流动、传热特性的相关准则,得出了雷诺数Re-摩擦系数f,雷诺数Re、普郎特数Pr-努谢尔特数Nu间关系的实验模型,并对该模型进行了分析。     

Multiple weak interaction‐assisted SERS detection platform for triadimefon

In this paper, a surface enhanced Raman spectra (SERS) detection platform for the widely used pesticide of triadimefon (TDF) is described. TDF is difficult to connect to the gold/silver SERS substrate, but the optical properties of the probe molecule 4‐mercaptobenzoic acid (4‐MBA), including the peak intensity and the peak position, are easily altered by the multiple weak interaction‐assisted SERS detection platform. The limit of detection (LOD) of this method is 1.0 × 10^‐9 M, and the linear range is from 1.0 × 10^‐6 M to 1.0 × 10^‐9 M. The linear region is from 1.0 × 10^‐6 M to 1.0 × 10^‐9 M, described by the equation y = 884.01x + 2.24 with a correlation coefficient (R²) of 0.9990. Interference of foreign metal ions with higher concentrations than common mineral water is too weak to the determination. Furthermore, physical insights into the phenomena and the detection mechanism were obtained and investigated theoretically. The preferential conformation of the complex and reduced density gradient (RDG) calculation results indicated that the interactions between TDF and 4‐MBA consisted of multiple weak interactions through two hydrogen bonds and one van der Waals interaction. The intermolecular interaction was negative for the charge transfer from the SERS substrate to the probe molecule; thus, the peak intensity decreased. TDF interacts directly with the carboxyl of the probe molecule and consequently has an effect on the ring vibrations. Copyright © 2014 John Wiley & Sons, Ltd.     

Electrocatalytic oxidation of nucleobases by TiO2 nanobelts

Two kinds of TiO(2) nanobelts were prepared from commercial P-25 powders via an alkaline hydrothermal method with and without an acid etching process. The uncauterized nanobelts (TNs) exhibited a smooth surface, and mixed phases of anatase and TiO(2) (B), whereas the cauterized ones (CTNs) displayed a rough surface and a pure anatase structure. TNs and CTNs were then deposited onto a glassy carbon electrode (GCE) surface with a conductive adhesive (CA), and the resulting chemically modified electrodes exhibited electrocatalytic activities in the oxidation of nucleobases in a 0.1 M phosphate buffer solution (PBS) at pH 7.4. For guanine and adenine, well-defined oxidation peaks were observed in voltammetric measurements at about +0.62 and +0.89 V, respectively, at a potential sweep rate of 100 mV s(-1), whereas for cytosine, uracil and thymine, the voltammetric features were not obvious. The average surface coverages (Γ) of guanine and adenine on the CTNs/CA/GCE electrode were estimated to be 4.75 × 10(-10) and 7.44 × 10(-10) mol cm(-2), respectively, which were about twice those at the TNs/CA/GCE electrode. The enhanced activity of the CTN-based electrode towards purine nucleobase oxidation was ascribed to the large specific surface area and anatase structures with enhanced (001) facets of the CTN that facilitated adsorption of the analytes onto the electrode surface and charge transport through the electrode surface layer.     

A chemoselective Reformatsky–Negishi approach to α-haloaryl esters

A practical synthesis of α-haloaryl esters has been achieved via a chemoselective Negishi coupling of poly-halogenated aromatics and Reformatsky reagents in the presence of catalytic Pd(dba)₂ and Xantphos. This chemistry tolerates a variety of aryl halides and was successfully applied to the synthesis of Ibuprofen. The α-haloaryl ester products, exemplified by ethyl 2-(4-bromo-2-chlorophenyl)acetate (3a), can be further functionalized via palladium or copper catalysis to afford an array of α-aryl esters.     

Simultaneous Degradation of Aqueous Trichloroacetic Acid by the Combined Action of Anodic Contact Glow Discharge Electrolysis and Normal Electrolytic Processes at the Cathode

To enhance the removal of trichloroacetic acid (TCA) by anodic contact glow discharge electrolysis (CGDE), the combined degradation of TCA by the action of anodic CGDE, denoted anodic degradation, and normal electrolytic processes at the cathode, denoted cathodic degradation, was investigated. Here, this overall process is termed simultaneous degradation. Compared to anodic degradation, in simultaneous degradation, the reduction rates for TCA and total organic carbon (TOC) increased from 65.32% and 62.03% to 91.82% and 73.03%, respectively. Meanwhile, the dechlorination rate rose from 64.6 to 80.12%. For simultaneous degradation, the disappearance of TCA, the reduction in the TOC, and the dechlorination of TCA, followed first-order kinetics. The reaction intermediates were detected and, based on the intermediates and the observed kinetics, the effects of the simultaneous degradation of TCA, TOC, and dechlorination of TCA are discussed. The cathode materials, length of the anode dipped into the electrolyte, and Pd loading on the Ni cathode all affected the simultaneous degradation of TCA significantly. The effect of the addition of Fe²⁺ was also investigated. The additive and synergistic effects of the combination of anodic and cathodic degradations on simultaneous degradation are discussed. Based on these results, an analysis of the degradation of TCA suggests that ·OH and ·H/e ^?_aq generated by the action of anodic CGDE, as well as the ·H_ads generated on the Pd-loaded Ni cathode surface, are the key species responsible for the dechlorination of TCA. Furthermore, possible mechanistic routes for the simultaneous degradation of TCA are proposed.

     

Spin-Dependent Thermoelectric Transport in Cobalt-Based Heusler Alloys

Sitting at the intersection of spintronics and thermoelectricity, research investigating the coupling of thermoelectric, magnetic, and electrical transport properties in materials has recently found that the ferromagnetic Heusler alloys are the ideal testbeds. These materials have attracted a lot of attention due to their useful magnetotransport properties and the possibility of tailoring these properties by modifying their composition or producing heterostructures. With the diverse range of interesting phenomena in the Heusler alloys, ferromagnetic Heusler alloys are also ideal candidates for engineering spin caloritronic devices that can take advantage of the interplay of the physics of heat flow, magnetism, and electric potential. The fundamental physical concepts important to spin-dependent thermoelectrics research are introduced and recent studies of several ferromagnetic Heusler compounds are reviewed, highlighting some exceptional latest experiments on half-metallic Co₂TiSn and the ferromagnetic Weyl semimetal Co₂MnGa. Furthermore, the potential to generate useful magnetothermoelectric voltages in electronic devices based on the anomalous Nernst effect is discussed.