Generalized Shifts on Cartesian Products

It is proved that if E, F are infinite dimensional strictly convex Banach spaces totally incomparable in a restricted sense, then the Cartesian product E×F with the sum or sup norm does not admit a forward shift. As a corollary it is deduced that there are no backward or forward shifts on the Cartesian product`p1×`p2,1\u3c p16=p2\u3c∞, with the supremum norm thus settling a problem left open in Rajagopalan and Sundaresan in J. Analysis 7 (1999(, 75-81 and also a problem stated as unsolved in Rassias and Sundaresan

神经网络机器翻译研究热点与前沿趋势分析

机器翻译是指利用计算机将一种语言文本转换成具有相同语义的另一种语言文本的过程。它是人工智能领域的一项重要研究课题。近年来,随着深度学习研究和应用的快速发展,神经网络机器翻译成为机器翻译领域的重要发展方向。该文首先简要介绍近一年神经网络机器翻译在学术界和产业界的影响,然后对当前的神经网络机器翻译的研究进展进行分类综述,最后对后续的发展趋势进行展望。国家自然科学基金(61672440)国家语委一般项目课题(YB135-49)厦门大学校长基金(ZK1024)国家重点研发计划(2019QY1803

Synthesis and Crystal Structure of Porous Zinc(Ⅱ) Coordination Polymer{[Zn(L)_2(H_2O)_2]·H_2O}_n Constructed by Isonicotinoylhydrazone Ligand

以邻甲酰基苯磺酸钠和异烟肼为原料在乙醇/水溶液中制备了一种酰腙类SCHIff碱配体(nAl),采用常规溶液挥发法合成了由该配体构筑的zn((Ⅱ)配位聚合物{[zn(l)2(H2O)2]·4H2O}n。利用元素分析、Ir、TgA和X-射线单晶衍射分析对配合物进行了表征。配合物晶体属三斜晶系,P1空间群,晶胞参数A=0.786 98(4)nM,b=0.869 26(5)nM,C=1.180 44(7)nM,α=103.353(5)°,β=100.965(4)°,γ=93.123(4)°,z=1,V=0.767 24(7)nM3,dC=1.697 g·CM-3。每个zn(Ⅱ)离子被2个配体l-阴离子双重桥联形成二核环状结构单元,并通过共用锌离子形成一维链配位聚合物,链与链之间通过氢键扩展为具有一维开放孔道的三维超分子网络结构。An acylhydrazone-type Schiff base ligand(NaL) was synthesized by reaction of sodium 2-formylbenzene sulfonate with isoniazide in a mixture of ethanol and water.A Zn(Ⅱ) coordination polymer {[Zn(L)2(H2O)2]·4H2O}n have been synthesized by employing the solution preparation method at room temperature and characterized by elemental analysis,IR,TGA and X-ray diffraction structural analysis.Crystal data:triclinic system,space group P1,a=0.786 98(4) nm,b=0.869 26(5) nm,c=1.180 44(7) nm,α=103.353(5)°,β=100.965(4)°,γ=93.123(4)°,Z=1,V =0.767 24(7) nm3,Dc=1.697 g·cm-3.Each Zn (Ⅱ) ion is bridged by two L-ligands in the monodentatemonodentate mode to form a ring-like dimer units,and a one-dimensional chain is built by sharing a Zn (Ⅱ) ion between the units.The adjacent chains are linked into a 3D supramolecular network structure via hydrogen bonds and π-π interactions with a 1D open channel that are occupied by solvent molecules.CCDC:934292.泉州师范学院学科建设资金; 国家级大学生创新创业训练计划项目(No.201310399018)资

高粱子粒淀粉表面色素的树脂分离研究

对纯化高粱淀粉过程中所得到的淀粉共生天然色素进行了树脂分离纯化研究。得到了树脂分离高粱淀粉共生色素的吸附动力学结果,3 种大孔吸附树脂 HPD-600、AB-8、H103 对高粱红的吸附为慢速平衡型。通过对树脂分离所得色素成份的红外光谱、紫外光谱、质谱分析得出,高粱籽粒淀粉共生色素与高粱壳中的高粱红主要成份是同样的物质,鉴定出所分离的主要成份之一为 5,7,4′-三羟基黄酮

Electrocatalytic Oxidation of Formic Acid on Pt-Se Hollow Nanosphere Modified Glassy Carbon Electrodes

Corresponding authors. Email: [email protected],[email protected]; Tel:+86-13879159319.[中文文摘]以无定形硒溶胶为模板制备了不同硒覆盖度(θSe)(θSe=0.49,0.39,0.06,0)的Pt-Se和Pt纳米空球(分别记为(Pt-Se)HN和PtHN),发展了利用亚硫酸盐彻底除去核壳纳米粒子上Se的方法.对获得的纳米空球进行了形貌和结构的表征,结果表明所制备的(Pt-Se)HN粒径均匀,分散性好,球壳呈多孔结构.以其作为电催化剂制备了(Pt-Se)HN修饰的玻碳(GC)电极((Pt-Se)HN/GC),利用常规电化学方法比较该电极与PtHN/GC和商用碳载铂(Pt/C)修饰GC(Pt/C/GC)电极对甲酸的催化氧化作用,发现对甲酸氧化的活性顺序为(Pt-Se)HN/GC>PtHN/GC>Pt/C/GC.三种电极催化甲酸氧化的机理有所不同:前者更倾向于通过弱吸附中间体直接氧化成CO2的单途径机理进行,后两者则通过强吸附和弱吸附中间体的双途径机理进行.在一定Se覆盖度条件下,(Pt-Se)HN/GC对甲酸的氧化有助催化作用.[英文文摘]Platinum-selenium and platinum hollow nanospheres(denoted as(Pt-Se)HN and PtHN,respectively) with different coverages of Se(θSe)(θSe=0.49,0.39,0.06,0) were prepared using amorphous Se colloids as a sacrificial template.Sulfite was used to completely remove Se from the core-shell nanoparticles.The morphology and structure of the nanoparticles were characterized using various methods,which revealed a hollow structure with a very uniform size distribution and a porous structure on the shell.Assembly of Pt-Se hollow nanospheres ((Pt-Se)HN) on a glassy carbon (GC) electrode produced a (Pt-Se)HN/GC electrode. The electrocatalytic activity of the electrode for the oxidation of formic acid was compared with the PtHN/GC and commercial Pt/C/GC electrodes by cyclic voltammetry and chronoamperometry. The activity followed the order:(Pt-Se)HN/GC > PtHN/GC >Pt/C/GC. The electrooxidation of formic acid on (Pt-Se)HN/C, PtHN/C, and Pt/C catalysts follows different mechanisms: the former tends to directly oxidize formic acid to CO2 via weakly adsorbed intermediates, and the latter two via both weakly and strongly adsorbed intermediates.(Pt-Se)HN with a suitable selenium content showed optimal electrocatalytic activity for the oxidation of formic acid.国家自然科学基金(20663002); 厦门大学固体表面物理化学国家重点实验室基金(200511)资助项

基于PXI轮边减速器结构参数优化设计

行星轮边减速器传动比大、结构紧凑且具备较强的承载能力。基于二级行星轮边减速器结构特点,保持总传动比不变,将齿数、模数及齿宽作为变量,在相同输入功率、转速下,当齿面接触强度和齿根弯曲强度达到一定安全系数时,寻求最优变量,使整体功率损失最小,进行优化设计;基于Simulink建立了最优解轮边减速器模型,并导入Labview,在Labview+PXI环境下实现模型实时仿真,对动态特性进行分析。结果表明,优化后,功率损失率由3. 87%降低至3. 31%;优化后轮边减速器各级齿轮传动啮合变形是混沌的,齿轮副啮合变形大小由其传递的力矩决定,受齿轮啮合时变刚度影响在稳定值周围波动,表明了优化设计的可靠性

Applications of atomic force microscopy in investigating tumors at the single-cell level

肿瘤现已严重威胁人类的生命健康。过去十年间在细胞生物力学方面的研究进展表明肿瘤的发生发展过程中总伴随着细胞表面超微形貌和机械特性的变化,为肿瘤研究带来了新的认识,有助于发展新型免标记临床疾病诊断技术。原子力显微镜(AFM)以其纳米级空间分辨率,溶液环境下对活体细胞、组织等生物样本进行成像、测量的独特优势,成为肿瘤细胞生物力学研究的重要工具。本文综述了AFM在肿瘤细胞机械特性测量,超微形貌成像,及分子识别方面的研究进展,对其面临的困难和挑战进行了讨论,并对其应用前景进行了展望

助溶剂对Ba_3Si_6O_(12)N_2:Eu~(2+)氮氧化物荧光粉制备及光学性能的影响（英文）

采用微波法制备了Eu~(2+)掺杂的Ba_3Si_6O_(12)N_2绿色氮氧化物荧光粉,着重研究了不同助熔剂:BaCl_2、H_3BO_3、KF和NH_4F对Ba_3Si_6O_(12)N_2:Eu~(2+)发光性能的影响。利用X射线衍射(XRD)、荧光光谱仪、扫描电子显微镜(SEM)和量子效率(QE)等检测方法研究了不同助溶剂的作用机理。研究结果表明:添加助溶剂能够显著提高荧光粉的发光强度,添加不同助溶剂制备荧光粉的发光强度大小依次为H_3BO_3>KF>BaCl_2>无助溶剂>NH_4F。当添加1.0wt%的H_3BO_3时,所制备的荧光粉粒径分布比较均匀,形貌较好,荧光粉的发光强度最大,且与不添加助溶剂制备的荧光粉相比,有较高的量子效率和吸收效率,不同温度下的发射光谱表明其热淬灭性低,荧光寿命较短