摘要：Bimetallic nanostructures have attracted great interest as efficient catalyst to enhance activity,selectivity and stability in catalytical ***,we report a facile one‐pot carbothermal route to in‐situ controllable synthesize heterogeneous bimetallic Ni3Fe NPs@C *** X‐ray diffraction,transmission electron microscopy,X‐ray photoelectron spectroscopy and N2 adsorption‐description results reveal that the Ni3Fe alloy nanoparticles are evenly embedded in carbon *** as‐prepared Ni3Fe NPs@C catalyst shows excellent selective hydrogenation catalytic performance toward the conversion of levulinic acid(LA)toγ‐valerolactone(GVL)via both direct hydrogenation(DH)and transfer hydrogenation(TH).In DH of LA,the bimetallic catalyst achieved a 93.8%LA conversion efficiency with a 95.5%GVL selectivity and 38.2 mmol g–1 h–1 GVL productivity(under 130°C,2MPa H2 within 2 h),which are 6 and 40 times in comparison with monometallic Ni NPs@C and Fe NPs@C catalysts,*** addition,the identical catalyst displayed a full conversion of LA with almost 100%GVL selectivity and 167.1 mmol g–1 h–1 GVL productivity at 180°C within 0.5 h in TH of *** optimal reaction conditions,the DH and TH catalytic performance of 500‐Ni3Fe NPs@C(3:1)catalyst for converting LA to GVL is comparable to the state‐of‐the‐art noble‐based *** demonstrated capability of bimetallic catalyst design approach to introduce dual‐catalytic functionality for DH and TH reactions could be adoptable for other catalysis processes.

摘要：In pursuit of low-cost direct formic acid fuel cells,tungsten carbide(WC)supported Pd catalyst is considered as an ideal candidate for efficient decomposition of formic acid due to low Pd utilization and excellent ***,different adsorption configurations and active sites of the intermediates,involved in the HCOOH decomposition,on WC(0001)-supported Pd monolayer(Pd/WC(0001))surface investigated by using density functional *** results reveal that trans-HCOOH,HCOO,cis-COOH,trans-COOH,HCO,CO,H2 O,OH and H exhibit chemisorption on Pd/WC(0001)surface,whereas cis-HCOOH and CO2 exhibit weak interactions with Pd/WC(0001)*** addition,the minimum energy pathways of HCOOH decomposition are analyzed to generate CO and CO2 due to the fracture of C–H,H–O and C–O *** adsorbed HCOOH,HCOO,mH COO,cis-COOH and trans-COOH configurations exhibit dissociation rather than *** formation occurs through the decomposition of cis-COOH,trans-COOH and HCO,whereas the CO2 formation happens due to the decomposition of *** is found that the most favorable pathway for HCOOH decomposition on Pd/WC(0001)surface is HCOOH→HCOO→CO2,where the formation of CO2 from HCOO dehydrogenation determines the reaction ***,CO2 is the most dominant product of HCOOH decomposition on Pd/WC(0001)*** presence of WC,as monolayer Pd carrier,does not alter the catalytic behavior of Pd and significantly reduces the Pd utilization.

摘要：金属负载型催化剂的界面结构设计一直是实现高效、高选择性催化反应的核心研究.本文表明,异质结结构PdNi&Ni_(3)N的界面电荷重新分布可以催化硝基苯选择性加氢成为偶氮类化合物.相比之下,独立的PdNi合金催化硝基苯转化为苯胺,而Ni_(3)N载体在相同条件下对硝基苯加氢的催化几乎没有效果. X射线光电子能谱和理论计算表明,PdNi&Ni_(3)N界面电荷重新分布导致有机反应中间体的吸附能发生变化,从而改变加氢反应途径,实现偶氮化合物的高选择性生成.本研究进一步表明了界面结构设计在有机催化加氢反应中的重要性,而且可能会引起研究者对于异质结构金属(合金)/过渡金属氮化物更多的科学兴趣,以应用于催化领域的不断发展.

摘要：During advanced water detection using the transient electromagnetic method, the exploration effect for water-rich area is often poor due to the interference of bolts that are distributed in different positions in working face. Thus, the study on the interference characteristics of bolts in different states has important directive significance for improving the acquisition quality and data processing method in water detection. Based on the analysis of the distribution laws of magnetic field excited by small multi-turn coincident loop in full space of homogeneity, the test on the interference of bolts has been designed in the mine. Through drilling 18 holes around the overlapping coil in the working face, mass data are collected in order with the posi- tion change and the exposed bolt length. The results of comprehensive data analysis show that the transient electromagnetic field is strongly interfered as the distance between the bolt and the center of the coil is less than 3 m, and the interference varies greatly as the distance varies. On the other hand, the field induced by the bolts can be ignored as the distance exceeds 3 m. The findings can help to improve data acquisition and correction during advanced water detection when using the transient electromagnetic method.

摘要：The SC200 proton therapy superconducting cyclotron was developed by ASIPP (Hefei, China) and JINR (Dubna, Russia). A measurement system was designed to assess the average radial component of the magnetic field (Brav) with 15 search coils in the median plane. The winding differences of the search coils affect the measurement accuracy of the Brav. Based on the electromagnetic induction principle, to measure the Brav accurately, this paper focuses on the design and commissioning of the Brav measurement system. The preliminary results confirm that the system design is reasonable and suitable. After testing the search coil at different speeds, the optimal speed was determined as 2.5 mm/s. The relative error was approximately 0.1% under the maximum radial component of the magnetic field Br of 7 G. The measurement precision was up to 1.0×10^-3, which can provide the required measurement tolerance of 3–7 G for Br in the median plane. The commissioning of the Brav measurement system is an important step for Br measurement. It can check and adjust the asymmetry of the superconducting coils (SCs).

摘要：Ag3PO4 is widely used in the field of photocatalysis because of its unique activity. However, photocorrosion limits its practical application. Therefore, it is very urgent to find a solution to improve the light corrosion resistance of Ag3PO4. Herein, the Z-scheme WO3(H2O)0.333/Ag3PO4 composites are successfully prepared through microwave hydrothermal and simple stirring. The WO3(H2O)0.333/Ag3PO4 composites are characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and UV-Vis spectroscopy. In the degradation of organic pollutants, WO3(H2O)0.333/Ag3PO4 composites exhibit excellent performance under visible light. This is mainly attributed to the synergy of WO3(H2O)0.333 and Ag3PO4. Especially, the photocatalytic activity of 15%WO3(H2O)0.333/Ag3PO4 is the highest, and the methylene blue can be completely degraded in 4 min. In addition, the stability of the composites is also greatly enhanced. After five cycles of testing, the photocatalytic activity of 15%WO3(H2O)0.333/Ag3PO4 is not obviously decreased. However, the degradation efficiency of Ag3PO4 was only 20.2%. This indicates that adding WO3(H2O)0.333 can significantly improve the photoetching resistance of Ag3PO4. Finally, Z-scheme photocatalytic mechanism is investigated.

摘要：目的:准双曲面齿轮副在实际装配过程中不可避免地存在安装误差。本文旨在建立考虑多种安装误差的准双曲面齿轮啮合模型,对齿轮副啮合印痕特征(齿面分布位置、大小和方向)进行参数化建模,精确评价印痕对安装误差的敏感性,以及研究降低接触性能对安装误差的敏感度的方法,为准双曲面齿轮副的加工和安装提供理论依据。创新点:1.对准双曲面齿轮齿面接触印痕进行精确的参数化建模;2.建立考虑轴交角误差、偏置距误差以及大小轮轴向误差的齿轮副啮合分析模型;3.建立准双曲面齿轮副安装误差敏感度综合评价模型;4.通过优化齿轮加工参数,在齿轮副设计环节实现齿轮副安装误差敏感度的降低。方法:1.对准双曲面齿轮副安装误差和齿面接触印痕进行参数化建模,推导出表示接触印痕大小、方向和齿面分布位置的解析表达式(公式(1)^(3));2.建立考虑4种安装误差的准双曲面齿轮副啮合分析模型(公式(4)^(11)),得到不同安装误差对啮合印痕的影响(图5~7);3.建立准双曲面齿轮副安装误差综合敏感度优化模型(公式(15)),并基于改进的多种群遗传算法(图14)实现齿轮副安装误差敏感性的降低(图8)。结论:1.四种安装误差对准双曲面齿轮啮合质量的影响程度不同;其中轴交角误差的影响最大,其次是偏置距误差,而大小轮的轴向安装误差的影响最小,因此安装齿轮副必须注重轴交角及偏置距的安装精度。2.通过降低齿轮副安装误差综合敏感度,可在一定程度上降低系统对装配误差的敏感性;在齿轮副设计环节加入安装误差敏感度分析,优化机床加工参数,对装配后的啮合质量控制具有积极意义。3.考虑安装误差的轮齿接触分析模型能够得到不同安装误差对啮合印痕及传动误差的影响规律,是一种对失配状态下的准双曲面齿轮副进行无载啮合分析的有效工具。

摘要：The recrystallization behavior,grain boundary characteristic distribution,and mechanical properties of pure Cu sheets that were subjected to different cold rolling paths,and then annealed at 400°C for 10,30,60,and 420 min,were *** rolling paths changed the grain boundary orientations of cold-rolled copper,causing recrystallized grains to nucleate and grow in an oriented ***,the evolution of the texture indicated that cold-rolled copper with different rolling paths did not show an obvious preferred orientation after *** RD-60 specimen exhibited the smallest grain size(6.6μm).The results indicated that the grain size and low-ΣCSL grain boundaries worked together to provide RD-60 samples with appropriate mechanical properties and high *** yield strength,ultimate tensile strength,and elongation of RD-60 sample were 81 MPa,230 MPa,and 49%,*** results could provide guidance for tuning the microstructures and properties of pure Cu foils,as well as designing fabrication routes for pure Cu foils through processes such as rolling and drawing.

摘要：Objective:Pediatric cancer patients endure multiple symptoms during treatment and also in *** health technologies provide an innovative way to support their symptom *** review aimed to examine the effect of digital health technologies on managing symptoms among across pediatric cancer ***:A systematic literature search of six English and three Chinese electronic databases was combined with hand searching,to identify eligible research studies from database establishment to November 30,*** reviewers carried out data selection,data extraction,and quality appraisal independently.A narrative approach was taken to summarize ***:Four randomized control trials,two quasi-experiments,and five one group pre-posttest designed studies,were included in the review with a total of 425 *** methodological quality of the studies was generally *** symptoms(anxiety,depression,pain,anger,fatigue,fear,distress)and seven digital health technologies(visual reality,website,humanoid robot,app,wearable devices,short messages and videoconference)were reported in the included ***:Current evidence supports the effect of digital health technologies is generally mixed and *** is a trend of positive effects found in the interventions that feature digital health technologies’interactive *** review highlights the need for further investigation with rigorous research designs and the consideration of influencing factors from the symptoms,participants,and context levels to inform a better digital health implementation.