Au(111)/咪唑基离子液体界面结构研究:阳离子侧链长度的影响

本文结合电化学方法与原子力显微镜力曲线技术,研究了两种烷基侧链长度不同的离子液体BMITFSA和OMITFSA在Au(111)电极表面附近的层状结构的数目和耐受力对电位的依赖性,探究了烷基侧链长度变化对界面层状结构的影响.研究表明,不同烷基侧链长度的离子液体体系力-电位曲线形状基本相似.在零电荷电位(the potential of zero charge,PZC)附近时,力值最小,因为此时电极表面荷电量较小,层状结构不稳定;电位偏离PZC的过程中,第一层层状结构力值呈现先增大后减小的趋势.受到烷基侧链所处的不同位置影响,在PZC电位以负,短侧链离子液体的层状结构稳定性较好,而PZC电位以正,长侧链离子液体的稳定性较好.国家自然科学基金项目(No.21673193);;福建省自然科学基金项目(No.2016J01075)资

金属固溶体热膨胀系数的CALPHAD计算模型

基于计算相图方法(CALPHAD方法),借鉴经典热容模型,通过增加额外的磁性项参数,构建了包含铁磁-顺磁转变的金属固溶体热膨胀系数的CALPHAD计算模型。结合Ni-Fe二元合金的实验结果,采用Levenberg-Marquardt法对模型参数进行了评估,优化得到了300～1200 K范围内Ni-Fe二元金属固溶体热膨胀系数的相互作用参数。采用得到的模型参数,对Ni-Fe二元金属固溶体的热膨胀系数进行了计算,计算结果准确地描述了Ni-Fe二元金属固溶体在居里温度附近的尖锐峰。随着Fe含量的增加,居里温度处的峰值减小,热膨胀曲线由峰状变成谷状,与实验值吻合。该计算模型可以准确计算任意Fe含量<50%(质量分数)的Ni-Fe二元金属固溶体的热膨胀系数。国家重点研发计划项目(2017YFB0701603,2016YFB0701401)福建省自然科学基金项目(2016J01256)国家自然科学基金青年基金项目(51601161

Selective methylation of toluene using CO2 and H2 to para-xylene

二甲苯（PX）是石化工业的基本有机化工原料之一，主要用于生产三大合成材料—合成树脂、合成纤维和合成橡胶。随着我国下游产业的快速发展，PX的需求量迅猛增长，进口依存度大于50%。袁友珠教授课题组提出使用CO2和H2替代甲醇作为甲苯烷基化试剂，利用CO2和H2在相对较低温度下生成的甲氧基中间体（无需经甲醇）直接与甲苯烷基化。化学化工学院2018级博士生左佳昌为论文第一作者，博士生陈伟坤、硕士生刘佳以及醇醚酯化工清洁生产国家工程实验室（厦门大学）段新平博士和叶林敏博士等参与了论文的部分研究。该研究结果已分别申请了中国发明专利（申请号201911149539.2, 2019）和国际专利（申请号PCT/CN2020/077412, 2020）。【Abstract】Toluene methylation with methanol to produce xylene has been widely investigated. A simultaneous side reaction of methanol-to-olefin over zeolites is hard to avoid, resulting in an unsatisfactory methylation efficiency. Here, CO2 and H2 replace methanol in toluene methylation over a class of ZnZrOx–ZSM-5 (ZZO-Z5) dual-functional catalysts. Results demonstrate that the reactive methylation species (H3CO*; * represents a surface species) are generated more easily by CO2 hydrogenation than by methanol dehydrogenation. Catalytic performance tests on a fixed-bed reactor show that 92.4% xylene selectivity in CO-free products and 70.8% para-xylene selectivity in xylene are obtained on each optimized catalyst. Isotope effects of H2/D2 and CO2/13CO2 indicate that xylene product is substantially generated from toluene methylation rather than disproportionation. A mechanism involving generation of reactive methylation species on ZZO by CO2 hydrogenation and migration of the methylation species to Z5 pore for the toluene methylation to form xylene is proposed.This work was supported by the National Key Research and Development Program of China (2017YFA0206801), the National Natural Science Foundation of China (21972113), and the Program for Innovative Research Team in Chinese Universities (IRT_14R31).该工作得到了国家重点研发计划（2017YFA0206801）、国家自然科学基金（21972113、91545115）和教育部创新团队（IRT_14R31）的资助

Analysis on the land use and cover change in Tianjin Binhai New Area based on the remote sensing

采用全国土地分类系统,基于lAndSAT卫星TM遥感影像与天津滨海新区1:50,000地形图,进行相应数据处理,编制出2000年、2005年、2010年三期滨海新区土地利用/覆盖分类图,并运用土地利用转移矩阵对近10年来天津滨海新区土地利用/覆盖变化进行定量分析。在此基础上,进一步分析了经济、人口等驱动因子对土地利用/土地覆盖的影响。结果表明:十年间,滨海新区的建筑用地面积增加显著,而绿地、湿地、滩涂等高生态价值的土地向建筑用地、未利用地等开发建设用地大幅度转化,后五年变化尤为显著。This paper carries out quantitative analysis on the land use/cover(LU/C) change of Tianjin Binhai New Area in recent 10 years through using land use transition matrix from the three-stage LU/C classification maps of 2000, 2005 and 2010 drafted by means of the National Land Classification System of China based on Landsat TM satellite remote sensing image and the Tianjin Binhai New Area 1:50 000 relief maps.On this basis, the impact of such driving factors as the economy and population on LU/C is further analyzed.The results show that the area of the building land in Binhai New Area has increased significantly over the ten years, and the greenland, wetland, and shoals of high ecological value have been dramatically transformed into the building land and unused land for the development and construction, and the change is more significant in the later five years

Transition from tunneling leakage current to molecular tunneling in single-molecule junctions

数十年来，半导体工业一直遵循基于“摩尔定律”所设定的发展蓝图，逐步提升集成电路芯片上晶体管的集成度和运行速度，减小器件尺寸。为探索这一尺寸极限，课题组基于机械可控裂结技术自主开发了具有飞安级电学测量和亚纳米级位移控制灵敏度的科学仪器，在国际上首次获取了一系列具有不同重复单元的寡聚苯乙炔类分子电导随电极间距的演变关系，并发现随着电极间距的缩小，器件电输运由通过分子器件电流占主导逐步转变到由隧穿漏电流占主导。对于本研究中具有最小尺寸的寡聚苯乙炔分子器件，其由于隧穿漏电流所制约的尺寸极限可小至0.66 nm，预示了有机分子器件在未来电子器件小型化方面具有重要的应用潜力。 这一研究工作是在化学化工学院洪文晶教授、萨本栋微纳研究院杨扬助理教授以及英国Durham University的MartinR. Bryce教授共同指导下完成的。能源材料化学协同创新中心iChEM Fellow刘俊扬博士为论文第一作者，博士研究生郑珏婷、李瑞豪和硕士研究生黄晓艳、唐永翔、皮九婵、本科生王飞等参与了研究工作。田中群教授、毛秉伟教授和师佳副教授为论文工作提供了重要指导。【Abstract】The tunneling leakage current will be a major quantum obstacle during miniaturization in the semiconductor industry down to the scale of several nanometers. At this scale, to promote charge transport and overcome the tunneling leakage current between the source and drain terminals, molecular electronic junctions offer opportunities by inserting molecules between these two electrodes. Employing a series of oligo(aryleneethynylene) (OAE) molecules, here we investigate the transition from tunneling leakage current to molecular tunneling in the single-molecule devices using mechanically controllable break junction (MCBJ) technique, and the transition distances of the OAE molecular junctions were determined and even down to 0.66 nm for OAE2 molecular junction, which demonstrates that the intrinsic charge transport properties of a single-molecule device can be outstripped from the tunneling leakage current. Consequently, molecular electronic devices show the potential to push the ultimate limit of miniaturization to the scale of several angstroms.This work was supported by the National Key R&D Program of China (2017YFA0204902). This work was also generously supported by the Young Thousand Talent Project of China, the EC FP7 ITN “MOLESCO” project number 606728, the National Natural Science Foundation of China (nos. 21703188, 21673195, 21503179), and the China Postdoctoral Science Foundation (2017M622060). 该工作获得科技部国家重点研发计划课题（2017YFA0204902），国家自然科学基金委（21673195、21703188、21503179）以及中国博士后科学基金（2017M622060）等项目的资助，也得到了固体表面物理化学国家重点实验室、能源材料化学协同创新中心的支持

Y型聚乙二醇干扰素琢-2b注射液治疗HCV基因2/3型慢性丙型肝炎患者疗效和安全性的多中心随机对照试验研究

目的以标准剂量的聚乙二醇干扰素(Peg IFN)α-2a联合利巴韦林作为阳性对照,评价新型试验药物Y型Peg IFNα-2b注射液联合利巴韦林治疗2型/3型慢性丙型肝炎(CHC)患者的疗效和安全性。方法采用多中心、随机开放、阳性药对照的Ⅲ期临床试验,筛选符合要求的2型/3型CHC患者,按照2:1的比例随机分配到Y型Peg IFNα-2b组和Peg IFNα-2a组,同时口服利巴韦林,疗程24 w,停药随访24 w。采用Abbott Real Time HCV Genotype II检测HCV基因型,采用Cobas Taq Man实时定量PCR法检测血清HCV RNA水平。详细记录不良事件。主要疗效指标为持续病毒学应答(SVR),并进行非劣效检验。结果本试验实际入组2型/3型CHC患者255例,实际治疗241例。全分析集(FAS)数据显示,158例试验组和83例对照组患者SVR分别为85.4%(95%CI 79.94%~90.94%)和79.5%(95%CI 70.84%~88.20%,P=0.2402);对符合方案分析集(PPS)人群分析显示,试验组和对照组患者SVR分别为87.9%(95%CI 82.45%~93.27%)和85.9%(95%CI 77.82%~94.01%,P=0.7060),率差的95%可置信区间均符合非劣效标准;对PPS人群分析显示,85.8%受试者获得了早期病毒学应答(RVR),RVR的阳性预测值为90.1%;试验组和对照组不良事件发生率相似,分别为95.6%和95.2%,严重不良事件发生率分别为3.8%和3.6%。结论应用Peg IFNα联合利巴韦林治疗2型/3型CHC患者,新型试验药物Y型Peg IFNα-2b具有与对照药物Peg IFNα-2a相似的疗效和安全性。国家科技部“十二五”重大专项(编号:2012ZX10002-003)；“重大新药创制”十二五科技重大专项(编号:2012ZX09303019)

a new method for fast simulation of 3d clouds

自然景观真实感的模拟是计算机图形学领域中的研究热点和难点之一.尽管人们对静态云的真实感模拟进行了大量的研究,动态云模拟的工作还比较少.动态云的快速模拟技术在计算机游戏动画、飞行视景仿真、影视广告等许多领域具有重要的应用价值.提出了一种三维动态云快速模拟的新方法.首先,在较低分辨率的网格上求解云运动的物理方程,获得动态云的速度场.然后,采用纹理漂移的方法来增加云的表面细节.通过充分利用GPU的加速性能,该算法可以达到较高的绘制速度.最后,对上述算法进一步优化处理,使其可以适用于多种硬件平台

Half-metallic Ferromagnetism of Heusler Compounds Sc_2VZ(Z=C,Si,Ge,Sn,Pb):a First-principle Study

采用基于密度泛函理论(dfT)第一性原理的投影缀加波方法 (PAW),结合广义梯度近似(ggA),系统研究了Hg2CuTI型HEuSlEr合金SC2Vz(z=C,SI,gE,Sn,Pb)的电子结构和磁性.研究发现HEuSlEr合金SC2Vz(z=SI,gE,Sn,Pb)在平衡晶格常数下表现出半金属铁磁性,其自旋向上态中的带隙宽度分别为0.345,0.354,0.387和0.173EV.计算得到SC2Vz(z=SI,gE,Sn,Pb)的总自旋磁矩均为整数(3.00μb),符合SlATEr-PAulIng规则.分析能带与态密度发现,半金属带隙的产生主要是由于SC和V原子d态电子之间强烈的杂化作用所致.同时计算结果也表明,在一定程度的晶格常数变化范围内,SC2Vz(z=SI,gE,Sn,Pb)合金仍能保持其半金属性质.Half-metallic properties of new Sc-based full Heusler compounds Sc2VZ(Z=C,Si,Ge,Sn,Pb)with Hg2CuTi-prototype structure are systematically investigated using first-principles calculations within generalized gradient approximation(GGA).It is predicted that all the Sc2 VZ Heusler compounds are half-metallic ferromagnets,except for Sc2 VC.The calculated band gaps of majority spin states are 0.345,0.354,0.387 and 0.173 eV for Sc2 VSi,Sc2VGe,Sc2 VSn and Sc2 VPb,respectively.The total magnetic moments of Sc2VZ(Z=Si,Ge,Sn,Pb)compounds are found to be 3.00μBper formula unit,which accords with the Slater-Pauling rule Mtot=18-Ztbetween the total magnetic moment(Mtot)and the total number of valence electrons(Zt)per unit cell.Moreover,the origin of half-metallic majority band gaps has been discussed in terms of band structures and density of states for Sc2VZ(Z=Si,Ge,Sn,Pb)compounds.It is found that the half-metallicity can be maintained within a relatively wide range of lattice constants for Sc2VZ(Z=Si,Ge,Sn,Pb)compounds.国家自然科学基金重点项目(50971109

L1结构γ′-Co(AlW)相的弹性性质和热力学性质的第一性原理研究

采用第一性原理方法并结合准简谐德拜模型,系统研究了W原子分数对Co基高温合金中γ′-Co(AlW)（x=0,0.25,0.50,0.75,1.0）相的弹性性质和热力学性质的影响.研究发现随W原子分数的升高,γ′-Co(AlW)相的弹性模量显著提高,而弹性各向异性的程度明显降低,同时γ′-Co(AlW)相由延性材料向脆性材料过渡转变.通过分析电荷密度和态密度的计算结果,发现随W原子分数的增大,Co和W之间共价键的结合强度呈现增大的趋势,并且Co原子间的电荷密度分布逐渐由各向异性向各向同性过渡转变.在有限温度下,随W原子分数的升高,γ′-Co(AlW)相的热容、热膨胀系数和焓均减小.国家国际科技合作专项(2014DFA53040)

Powder Microelectrode Modified with Nafion-Os(bpy)_3~( 2+) and PVP Composite and Its Catalysis for NO_2 - Reduction

本论文简述用Nafion_Os(bpy) 3 2 + /PVP复合膜修饰的乙炔黑粉末微电极 ,以亚硝酸根还原为模型反应 ,实现从复合修饰及扩大电极比表面两方面改善电极性能的思路 .结果表明 ,它同时显示Nafion_Os(bpy) 3 2 + /PVP修饰电极对NO2 -及NO+ 双重富集并再生活性粒子NO+ 、防止中继体流失、加速膜中中继体传输、改变反应途径等复合修饰电极的多种功能以及粉末微电极的高比表面、高液相传质速度以及薄层效应的特性 .与平面修饰电极及裸粉末微电极相比 ,它明显提高了酸性溶液中亚硝酸根还原的可逆性、呈数量级地提高稳态极限电流密度以及NO2 -的检测指标 .The modified powder microelectrode was prepared by etching a Pt (0.1 mm diameter) disk microelectrode and filling in thus formed cavity with Nation_Os(bpy) 3 2+ /PVP composite modified carbon powder. The composite modified powder microelectrode showed cyclic voltammetric behaviors changing with the mole ratio (denoted X) of SO 3 - to Os(bpy) 3 2+ in Nafion. When X=3, a single pair of current peaks appeared near 0.6V (vs. SCE) due to Os(bpy) 3 2+/3+ redox couple. In contrast, for X=20, a pair of additional current peaks occurred near 0.4V. Both X=3 and X=20 modified powder microelectrodes strongly catalyzed the first electron reduction of nitrite in 0.5 mol/L H 2SO 4. The catalysis was so effective that the steady state polarisation curve showed essentially reversible characteristics with a plateau current density 2.18 mA/cm 2 and half_wave potentials near 0.55 V. While the electrode with X=3 could catalyze nitrite reduction only to the first electron transfer, the modified powder microelectrode with X=20 could catalyze the second electron transfer, resulting in an additional current wave starting near 0.4 V with a plateau current twice the first one. The plateau current densities obtained with the composite modified powder microelectrodes were much larger than those obtainable with flat electrodes (with or without modification), verifying the idea of advantageous combination of the composite modification and the porous electrode technique. The composite modified powder microelectrodes showed high performance in nitrite detection: sensitivity 814 mAL/cm 2 mole, linearity 10 _6 ～0.25 mol/L, lower detection limit 10 _6 mol/L; no interference from 0.1 mol/L ascobic acid, Fe 3+ ,Fe 2+ ,Mg 2+ ,K +,NH 4+ ,Cl -,NO - 3 and PO 3_ 4.作者联系地址：武汉大学化学系!湖北武汉430072,武汉大学化学系!湖北武汉430072Author's Address: Dept. of Chem., Wuhan Univ., Wuhan 430072, Chin