AuCu Alloy Nanoparticle Embedded Cu Submicrocone Arrays for Selective Conversion of CO2 to Ethanol

The CO₂ reduction reaction (CO₂RR) driven by renewable electricity represents a promising strategy toward alleviating the energy shortage and environmental crisis facing humankind. Cu species, as one type of versatile electrocatalyst for the CO₂RR, attract tremendous research interest. However, for C₂ products, ethanol formation is commonly less favored over Cu electrocatalysts. Herein, AuCu alloy nanoparticle embedded Cu submicrocone arrays (AuCu/Cu‐SCA) are constructed as an active, selective, and robust electrocatalyst for the CO₂RR. Enhanced selectivity for EtOH is gained, whose Faradaic efficiency (FE) reaches 29 ± 4%, while ethylene formation is relatively inhibited (16 ± 4%) in KHCO₃ aqueous solution. The ratio between partial current densities of EtOH and C₂H₄ (j_EtOH/j_C2H4) can be tuned in the range from 0.15 ± 0.27 to 1.81 ± 0.55 by varying the Au content of the electrocatalysts. The combined experimental and theoretical calculation results identify the importance of Au in modifying binding energies of key intermediates, such as CH₂CHO*, CH₃CHO*, and CH₃CH₂O*, which consequently modify the activity and selectivity (j_EtOH/j_C2H4) for the CO₂RR. Moreover, AuCu/Cu‐SCA also shows high durability with both the current density and FE_EtOH being largely maintained for 24 h electrocatalysis.     

天生桥一级水电站混凝土防渗面板水下检查及修复

天生桥一级水电站大坝上游防渗面板存在渗漏现象,为保证大坝安全运行,对水下面板潜水检查,并用HK-963水下黏结剂、SR防渗盖片等材料修补后渗水量明显减少,保证了大坝继续安全运行。     

The preparation and properties of some petroselinylamine derivatives

Petroselinylamine (cis-6-octadecenylamine) has been prepared by an improved process in which petroselinic acid in xylene is subjected to ammonolysis and treated further to yield the pri-mary amine without isolating the intermediate products. In addition, the petroselinylamine has been reacted with acrylonitrile, followed by reduc-tion with metallic sodium and alcohol, to give N-substituted petroselinyl-l,3-trimethylenediamine adducts, and with ethylene oxide under pressure to yield the oxyethylated tertiary amine deriva-tives. The crude products in each case were mix-tures of derivatives of various molecular weights. It was possible to isolate the N-petroselinyl-1,3-trimethylenediamine in its pure form from the crude mixture of hydrochloride salts by repeated recrystallizations from aqueous ethanol. The mix-ture of petroselinylamine-ethylene oxide deriva-tives could not be separated. 1 Presented at the AOCS Meeting, Cincinnati, October 1965. 2 So. Utiliz. Res. Dev. Div., ARS, USDA.     

The preparation and properties of some nitrogen-containing derivatives of petroselinic acid

Petroselinonitrile was prepared by distilling the ammonolysis products of petroselinic acid over phosphorus pentoxide, and also from parsley seed oil without first isolating the petroselinic acid. A high-boiling antioxidant was employed during the reaction to control polymerization. The reaction by-products were segregated from the pure petroselinonitrile by urea complexing. Petroselinamide was obtained from petroselinic acid by the acidolysis of urea. Although it was not possible to reduce the petroselinonitrile by catalytic hydrogenation without affecting the ethylenic linkage or without producing a mixture of the primary, secondary, and tertiary amines, petroselinonitrile was converted to primary petroselinylmine in good yields by reduction with metallic sodium and alcohol in toluene. The hydrochloride and the acetyl derivative of the pure primary amine have also been prepared. Presented at the AOCS meeting in New Orleans, Louisiana, May 7–9, 1962. One of the laboratories of the Southern Utilization Research and Development Division, Agricultural Research Service, U.S.D.A.     

Fabrication of Ni-matrix carbon nanotube field emitters using composite electroplating and micromachining

Ni-matrix carbon nanotube (CNT) field emitters have been fabricated by composite electroplating and micromachining (CEMM) at room temperature. Pretreated multi-walled CNT and Ni are deposited onto a Cr/Cu conducting layer by composite electroplating and protruding tips of CNTs are obtained as emitters by etching away a layer of Ni, followed by emitter pixels which are formed by micromachining. Through the process of CEMM, CNTs are vertically embedded in the flat Ni substrate. No further treatment is needed to initiate or augment field emission and the field emitters exhibit good field-emission properties such as high current density (13 mA cm⁻² at an applied electric field of 3.4 V μm⁻¹), low turn-on field (0.53 V μm⁻¹), and good stability (110 h for 10% degradation of current density from 400 μA cm⁻²).     

大型风电场无功补偿问题的探讨

介绍了无功补偿的基本原理以及风电场无功补偿所用的主要装置、风电场无功补偿的配置等。     

基于神经网络的机器人控制精度优化方法与技术研究

针对工业生产过程中机器人操作时控制精度不高的问题,采用具有自学习、自适应的智能控制手段——神经网络进行优化控制,将整个操作过程的控制精度由被训练后的网络来优化,从而提高控制精度,提高效率。     

Jet electrodeposition with movable,flexible friction on quality of nanocrystalline nickel coatings

To improve the deposition rate and quality of nanocrystalline nickel coatings, a method involving movable, flexible friction, jet electrodeposition (MFFJE) was proposed in this paper. The effects of cathode scanning speed and current density on electrodeposited nickel coatings prepared by MFFJE were investigated. Compared with traditional jet electrodeposition, the results showed that MFFJE exerted remarkable effects, improving the deposition rate and quality of nickel coatings, and, when the cathode scanning speed was 1000?mm?min^?1, the coating surface morphology was best. The maximum processing current density of nickel plating was more than 250?A?dm^?2. The grain size was decreased to 11.7?nm, hardness increased to 546?HV, and coating corrosion resistance significantly improved.     

Abnormal Graphitization Behavior in Near-Surface/Interface Region of Polymer-Derived Ceramics

The in situ free carbon generated in polymer-derived ceramics (PDCs) plays a crucial role in their unique microstructure and resultant properties. This study advances a new phenomenon of graphitization of PDCs. Specifically, whether in micro-/nanoscale films or millimeter-scale bulks, the surface/interface radically changes the fate of carbon and the evolution of PDC nanodomains, promotes the graphitization of carbon, and evolves a free carbon enriched layer in the near-surface/interface region. Affected by the enrichment behavior of free carbon in the near-surface/interface region, PDCs exhibit highly abnormal properties such as the skin behavior and edge effect of the current. The current intensity in the near-surface/interface region of PDCs is orders of magnitude higher than that in its interior. Ultrahigh conductivity of up to 14.47 S cm⁻¹ is obtained under the action of the interface and surface, which is 5–8 orders of magnitude higher than that of the bulk prepared under the same conditions. Such surface/interface interactions are of interest for the regulation of free carbon and its resultant properties, which are the core of PDC applications. Finally, the first PDC thin-film strain gauge that can survive a butane flame with a high temperature of up to ≈1300 °C is fabricated.     

磷酸系无机粘合剂的研究动态

本文叙述了磷酸系无机粘合剂在提高耐水性、耐热性、粘接强度等方面的研究开发动态。