等离激元共振光转热增强负载纳米金对丁二烯选择性加氢的催化性能

采用阳离子吸附法制备了氧化石墨烯负载纳米金(Au)催化剂(Au/GO), 通过调变Au的负载量(质量分数0.2%~2%), 实现了Au在10~21 nm粒径的可控制备. 室温下热红外测试显示0.2 W/cm²光照条件下, 随着金属负载量和粒径的增加, Au/GO光热温度可升高至110 ℃, 且光热转换效率高达88%. 研究发现, 以丁二烯的选择性催化加氢作为探针反应, 在0.2 W/cm²光照条件下, 丁二烯的转化率随Au负载量的增加先升高后降低, 丁烯选择性在90%以上; 当金负载量为0.5%(颗粒尺寸约15 nm), 光热转换温度为100 ℃时, 样品表现出较高的丁二烯转化率(99%)和丁烯选择性(90%), 且催化剂经过144 h稳定性测试无失活趋势. 与同等条件下的热催化反应相比, 光-热驱动的Au/GO的催化活性提高了5倍. 原位X射线光电子能谱测试分析表明, Au/GO催化性能的提升主要来源于等离子体光转热过程中激发纳米金表面产生了大量的Au ^δ+活性位点.     

Enhanced arbitrated quantum signature scheme using Bell states

We investigate the existing arbitrated quantum signature schemes as well as their cryptanalysis, including intercept- resend attack and denial-of-service attack. By exploring the loopholes of these schemes, a malicious signatory may success- fully disavow signed messages, or the receiver may actively negate the signature from the signatory without being detected. By modifying the existing schemes, we develop counter-measures to these attacks using Bell states. The newly proposed scheme puts forward the security of arbitrated quantum signature. Furthermore, several valuable topics are also presented for further research of the quantum signature scheme.     

金属有机骨架高温自还原制备高性能等级孔碳负载Co基催化剂

以钴基金属有机框架为前驱体, 利用一步高温碳化自还原法, 通过精确调控碳化过程, 实现等级孔道结构及钴纳米颗粒分散性的可控调节, 制备出高催化活性及产物选择性的等级孔碳负载Co基催化剂. 研究发现, 600 ℃碳化后的催化剂为具有高比表面积的等级孔道结构和高分散的钴纳米颗粒, 在选择性催化1,3-丁二烯加氢反应中, 丁二烯完全转化温度低至60 ℃, 对应丁烯的选择性高达61%, 实现了低温高选择性催化加氢.     

赋范线性空间中广义φ-半压缩映射的迭代逼近

研究了实赋范线性空间中一致连续广义φ-半压缩映射带误差的Ishikawa序列迭代逼近问题,改进和推广了现有的结果.     

渐近伪压缩映象的Ishikawa迭代序列强收敛的充要条件

在一般的实Banach空间中,研究Lipschitz渐近伪压缩映象和渐近非扩张映象不动点的迭代逼近问题.给出Ishikawa迭代序列强收敛的充要条件,所得结果改进和推广了张石生,肖建中等人的主要结果,修正和推广了朱玲娣等人的相应结果.     

Multiple modes of perpendicular magnetization switching scheme in single spin—orbit torque device

Spin—orbit torque (SOT) has been considered as one of the promising technologies for the next-generation magnetic random access memory (MRAM). So far, SOT has been widely utilized for inducing various modes of magnetization switching. However, it is a challenge that so many multiple modes of magnetization switching are integrated together. Here we propose a method of implementing both unipolar switching and bipolar switching of the perpendicular magnetization within a single SOT device. The mode of switching can be easily changed by tuning the amplitude of the applied current. We show that the field-like torque plays an important role in switching process. The field-like torque induces the precession of the magnetization in the case of unipolar switching, however, the field-like torque helps to generate an effective z-component torque in the case of bipolar switching. In addition, the influence of key parameters on the mode of switching is discussed, including the field-like torque strength, the bias field, and the current density. Our proposal can be used to design novel reconfigurable logic circuits in the near future.     

广义最速下降法逼近拟增生算子方程解的一个特征条件

倪仁兴最近的文章研究了广义最速下降法强收敛于拟增生算子方程解的一特征条件．本文对此进行了修正和改进，给出了一个新的特征条件．所得结果同时改进和推广了一些已有的结果．     

基于面向对象分类约束的融合方法研究

像素级融合方法中常出现色彩突变或色彩失真现象。通过分类信息对融合进行约束可以部分消除目标地物边界的这些现象。然而传统的基于像素分类的影像融合方法由于分类中的“椒盐效应”,导致融合效果受到一定的影响和限制。采用面向对象分类约束的方法对该融合方法进行改进。首先采用面向对象分类方法进行影像分类,解决了基于像素分类中的“椒盐效应”问题;其次将分类结果作为影像融合的约束条件,利用色度饱和度明度(HSV)变换进行融合;最后将该方法的结果与多种融合方法的结果进行定量比较,发现该方法除在目视上取得很好的增强效果外,在信息熵、方差等指标上也取得了很好的效果。     

Measurements of g-Factor of Rotational Levels in ^83Y

The g-factors of the positive parity rotational levels up to spin Ⅰ= 41/2 in ^83Y have been measured by a transient-magnetic-field ion implantation perturbed angular distribution method. The experimentally measured g-factors show the g9/2 proton alignment followed by the g9/2 neutron alignment. The measured g-factors are in good agreement with the results calculated by an empirical formula based on the cranking shell model.     

介孔SiO_2包覆Ag/ZIF-8核壳型催化材料的合成

通过液相自组装制备了Ag/ZIF-8;进一步以十六烷基三甲基溴化铵(CTAB)为结构导向剂,在疏水Ag/ZIF-8颗粒表面包覆一层介孔二氧化硅(MS)壳,合成了具有核壳结构的Ag/ZIF-8@MS催化剂,并对其进行了结构和性能表征.结果表明,Ag/ZIF-8@MS具有均一的颗粒尺寸(Ag/ZIF-8@MS粒径约为100 nm,Ag粒径约为15 nm)、较高的比表面积(539 m~2/g)及较大的孔体积(0.64 m~3/g);透射电子显微镜表征结果表明,介孔二氧化硅表层厚度约为20 nm.于550℃煅烧后,催化剂结构转变成Ag/Zn O@MS核壳结构.以催化对硝基苯酚生成对氨基苯酚为模型反应,对2种结构的Ag催化剂的催化性能进行了测试.催化反应结果表明,核壳型结构Ag/ZIF-8@MS材料催化对硝基苯酚反应的转化率超过95%,证明了这种以ZIF-8为载体的核壳型材料的优势.