生物可降解聚丁二酸/苯基丁二酸丁二醇酯系列共聚物的合成及其结晶行为

合成了一系列聚丁二酸/苯基丁二酸丁二醇共聚酯(PBSBS),利用DSC、1H-NMR和X射线等测试手段对共聚物组成、热力学性能、结晶性能、等温结晶行为进行了表征和研究.结果表明,含苯基的共聚单元的引入显著改变了聚丁二酸丁二醇酯(PBS)的热力学性能4,利用Hoffman-Week曲线得到的共聚物平衡熔点随共聚组分含量的增加显著降低,玻璃化转变温度则明显升高,结晶熔点符合无规共聚物的Flory方程.此外,利用Avrami方程对均聚物PBS以及共聚物PBSBS-10分别进行了等温结晶行为研究,结果表明共聚使结晶速率降低,PBS和PBSBS-10的Avrami指数分别介于2.8~3.0和2.7~2.9之间,结晶方式为三维生长异相成核,X射线测试结果表明共聚不影响晶体结构.     

苯酚和草酸二甲酯在不同分子筛催化下的酯交换反应

研究了以TS－1、H－ZSM－5、Hβ和H－丝光沸石等不同分子筛为催化剂，苯酚和草酸二甲酯酯交换合成草酸二苯酯反应。通过对催化剂进行吸附吡啶的红外光谱和NH3－TPD表征，考察了不同分子筛催化剂的酸性和酸强度对草酸二苯酯合成反应的影响，确定了催化剂上的弱酸中心是催化苯酚和草酸二甲酯酯交换合成草酸二苯酯反应的活性位，且催化剂的酸性中心越多，酸量越大，催化活性越好。催化剂上的强酸中心促进了副产物苯甲醚的生成。     

奇偶相干态的高阶压缩及其准概率分布函数

本文研究了奇偶相干态的高阶压缩和它们的各种准概率分布函数,结果表明,这两个态的高阶压缩性质是相互排斥的,特征函数和Wigner函数都不是高斯型,而且Wigner函数也不恒为正定,准概率密度(QPD)图形既不是椭圆,也不是月牙状,而是两叶花瓣状,显示出态的QPD图形不能说明态的压缩类型。 关键词：     

元素的起源与0号元素

论述元素的起源是以中子为起点,中子是特殊的0号元素。以中子的衰变特点、核反应的特点、与质子类同的特点、与稀有气体元素类同的特点以及中子星的存在、四中子的发现等论据,提出应当把中子看作元素并纳入元素周期表中。建议给这个特殊的元素命名为"中"。     

Free-space propagation of autofocusing Airy vortex beams with controllable intensity gradients

Vortex splitting is one of the main causes of instability in orbital angular momentum(OAM) modes transmission. Recent advances in OAM modes free-space propagation have demonstrated that abruptly autofocusing Airy vortex beams(AAVBs) can potentially mitigate the vortex splitting effect. However, different modes of vortex embedding will affect the intensity gradients of the background beams, leading to changes in the propagation characteristics of vortex beams. This study presents the unification of two common methods of coupling autofocusing Airy beams with vortices by introducing a parameter(m), which also controls the intensity gradients and focusing properties of the AAVBs. We demonstrate that vortex splitting can be effectively reduced by selecting an appropriate value of the parameter(m) according to different turbulence conditions. In this manner,the performance of OAM-based free-space optical systems can be improved.     

Image charge effect on the light emission of rutile TiO_2(110) induced by a scanning tunneling microscope

The plasmon-enhanced light emission of rutile TiO_2(110) surface has been investigated by a low-temperature scanning tunneling microscope(STM). We found that the photon emission arises from the inelastic electron tunneling between the STM tip and the conduction band or defect states of TiO_2(110). In contrast to the Au(111) surface, the maximum photon energy as a function of the bias voltage clearly deviates from the linear scaling behavior, suggesting the non-negligible effect of the STM tip on the band structure of TiO_2. By performing differential conductance( dI/dV) measurements, it was revealed that such a deviation is not related to the tip-induced band bending, but is attributed to the image charge effect of the metal tip, which significantly shifts the band edges of the TiO_2(110) towards the Femi level(E_F) during the tunneling process. This work not only sheds new lights onto the understanding of plasmon-enhanced light emission of semiconductor surfaces, but also opens up a new avenue for engineering the plasmon-mediated interfacial charge transfer in molecular and semiconducting materials.     

Improved performance of Au nanocrystal nonvolatile memory by N_2-plasma treatment on HfO_2 blocking layer

The N_2-plasma treatment on a HfO_2 blocking layer of Au nanocrystal nonvolatile memory without any post annealing is investigated. The electrical characteristics of the MOS capacitor with structure of Al–Ta N/HfO_2/Si O2/p-Si are also characterized. After N_2-plasma treatment, the nitrogen atoms are incorporated into HfO_2 film and may passivate the oxygen vacancy states. The surface roughness of HfO_2 film can also be reduced. Those improvements of HfO_2 film lead to a smaller hysteresis and lower leakage current density of the MOS capacitor. The N_2-plasma is introduced into Au nanocrystal(NC) nonvolatile memory to treat the HfO_2 blocking layer. For the N_2-plasma treated device, it shows a better retention characteristic and is twice as large in the memory window than that for the no N_2-plasma treated device. It can be concluded that the N_2-plasma treatment method can be applied to future nonvolatile memory applications.