Single-unit-cell thick Mn3O4 nanosheets

Single-unit-cell thick Mn(3)O(4) sheets were synthesized in an aqueous solution at room temperature. These nanosheets have a 001 orientation and are terminated at the Mn(2)O(4) atomic layer. Due to the huge shape anisotropy, they demonstrated lower T(C) and much greater coercivity than those of bulk Mn(3)O(4), respectively.     

Voltage-expandable liquid crystal surface

Based on dielectrophoretic effect, we report a novel approach which can extensively spread a liquid crystal (LC) interface. With interdigitated striped electrodes, the droplets can be stretched along the striped electrode direction; while with zigzag interdigitated electrodes, the droplets can be further stretched sidewise. In our demonstration, the occupied area of a 1.9-mm-aperture LC droplet doped with 1.2 wt% black dye could be expanded over ～3.5× at 78 V(rms). The spreading and recovering times were measured to be ～0.39 s and ～0.75 s, respectively. The slower response time confirms the extreme expanding of the LC surface. The contrast ratio is over ～120?:?1 in transmissive mode. Color light switch was also demonstrated by spreading colored-dye doped LC droplets. The mechanical stability of the device was also evaluated. Liquid devices based on this cell structure have the advantages of good stability, simple operation and low power consumption. This work opens a new gateway for voltage controllable, polarization-insensitive, and broadband liquid photonic devices which may find numerous applications in switchable windows, variable optical attenuators, and displays.     

Flat polymeric microlens array

A polymer-based flat microlens array is demonstrated. Within each pixel of the array, the polymer presents a circular central-symmetric inhomogeneous orientation. Pixel with such a structure behaves a lens-like character. A suitable amount of liquid crystal mixed in the polymer host can improve not only the lens flexibility but also the lens performance. Moreover, the polymer-based microlens array has the advantages of real planar surface, ultra-thin thickness, and can be designed with any aperture size.     

灯泵浦激光器输出激光稳定性实验研究

分析了灯泵浦激光器的特点以及影响其输出激光稳定性的原因,提出了在激光器谐振腔内加一个“Q开关”的方法来控制输出激光的稳定性,以氙灯泵浦的被动锁模Nd:YAG激光器为例进行了实验研究,证实了此方案是可行的.     

β修正光度法测定微量成分及络合比研究：Fe（Ⅱ）－EBT显色体系

在ｐＨ４－５ＨＡｃ－ＮａＡｃ溶液中，Ｆｅ（Ⅱ）与铬黑Ｔ（ＥＢＴ）反应，显色液由蓝变红色。反应较灵敏，ＥＤＴＡ和硫脲可使反应对Ｆｅ２＋具有选择性。本文研究β修正光度法测定微量铁并计算其络合比，该方法能消除显色液中过量显色剂干扰，提高测定灵敏度、准确度和精密度，测定结果表明，铁－ＥＢＴ络合比１：２，相对标准偏差ＲＳＤ≤４．３％，回收率９０．７～１０８％。适合于水及矿石、食品中铁的分析。     

2，5─哌嗪二酮与α，β─不饱和醛反应研究

综合运用了多种波谱学方法及化学手段确证并归属了２，５－哌嗪二酮与α，β－不饱和醛在超声波分散金属钾及双季铵盐作用下反应产物的立体化学与核磁共振信号，为研究这个反应提供了有用的信息．     

On dimension formulas for Jacobi forms

In this paper, we discuss the dimension formula for Jacobi forms via the Selberg trace formula, an explicit dimension formula for the space of Jacobi cusp forms of degree 2 is given as an application.     

Quasi-positive families of continuous Darcy-flux finite volume schemes on structured and unstructured grids

New families of flux-continuous control-volume distributed finite volume schemes are presented for the general full-tensor pressure equation arising in porous media and formulated for structured and unstructured grids. These schemes offer the practical advantage of being flux-continuous while only depending on one degree of freedom per control-volume, unlike rival approximations such as the Mixed Finite Element method. M-matrix bounds are presented, quasi QM-matrices are defined and an optimal quadrilateral scheme is identified. Anisotropy favoring triangulation is also shown to yield an optimal scheme. The new schemes prove to be relatively robust for the cases tested, including strongly anisotropic full tensor fields. Strong oscillations encountered with the earlier formulations, are removed or minimized.     

氯代烷烃、硫粉和氢亚磷酸酯一步合成S-烷基硫磷酸酯

S-苄基硫磷酸酯和S-烷基硫磷酸酯在农药中有着重要的应用。 本文发展了一种无需催化剂,仅在碱作用下,氯代烷烃、硫粉以及氢亚磷酸酯三组份一步生成S-烷基硫磷酸酯的绿色经济方法,该反应可以在一步反应中同时构建磷—硫键和碳—硫键。 以苄氯及衍生物、硫粉、氢亚磷酸酯在碳酸铯的促进下,室温反应,共合成了17个S-苄基硫磷酸酯,产率为70%~99%。 同时,实现了脂肪链的氯代烃、硫粉和氢亚磷酸酯的反应,在三乙胺的促进下,在空气中60 ℃反应,共合成了13个S-烷基硫磷酸酯,产率为45%~93%。 本方法在合成上和工业上将具有较好的应用前景。     

纳米光学传感器用于检测汞离子

汞离子是毒性最大的重金属之一,对环境和人体都会造成严重的不良影响,开发能够快速检测环境中汞离子的分析方法引起了越来越多的关注。纳米材料由于其优良的光学性能和良好的稳定性,被广泛用于环境中汞离子的检测。本文主要综述了近年来一些代表性的基于纳米材料的汞离子荧光、比色传感器。根据纳米材料的不同,将这些传感器分为基于金、银、碳和硅基材料,以及量子点、有机纳米颗粒和其他纳米基材料的荧光、比色传感器,并分别从设计原理、识别性能和实际应用等方面对这些传感器进行了描述和讨论。最后对该领域的研究和发展提出了展望。