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31.
We report on fast-switching and high-efficient optical beam steering based on a polymerisable liquid crystal polarisation grating (PG) in combination with ferroelectric liquid crystal (FLC) phase shutter. The PG was fabricated in a convenient single-step holographic exposure process using photo-sensitive azo-dye material as alignment layer for liquid crystal (LC) director. A binary electro-optical FLC was employed for circular polarisation selection, which enables the electro-tunable steering of the combined system. The efficiency of 95.7% with 82 μs switching time is obtained for 1064 nm laser. This work provides a versatile candidate for non-mechanical beam steering devices. 相似文献
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33.
应用亚硝酸钠-硝酸铝-氢氧化钠体系分光光度法测定核桃花青皮中总黄酮含量时受到共存的胡桃醌和焦性没食子酸的明显干扰,经试验,提出了消除此干扰的校正方法。从乙醇提取液中移取两份等量试液(2.0mL),分别置于25mL容量瓶中,其中一份按方法加显色混合液,以试剂空白为参比,在波长508nm处先后于15,25min测其吸光度A1及A2;另一份中加乙醇(1+1)溶液13mL及40g·L-1氢氧化钠溶液10.0mL,摇匀,测其吸光度A0。根据所推导的公式计算总黄酮的吸光度,代入回归方程计算其含量。按改进的方法分析3份样品,测定值的相对标准偏差(n=6)在0.76%~1.3%之间。加标回收试验的回收率在89.0%~105%之间。 相似文献
34.
采用溶剂热合成法,借助十六烷基三甲基溴化铵(CTAB)和十八烷基三甲基溴化铵 (STAB)的修饰合成了富含硫缺陷的ZnIn2S4-CTAB和ZnIn2S4-STAB光催化剂. 通过透射电镜、X射线衍射、紫外可见漫反射光谱、电子顺磁共振和光电化学性能测试对所有样品进行了表征,并通过光催化甲苯氧化反应测试样品的催化活性. 活性结果表明ZnIn2S4-CTAB和ZnIn2S4-STAB上甲苯转化速率分别达到795 μmol gcat-1 h-1和1053 μmol gcat-1 h-1,是未修饰ZnIn2S4-Blank催化剂的4倍和5倍,同时目标产物苯甲醛选择性均大于92%. 机理研究发现,表面活性剂修饰后的ZnIn2S4-CTAB和ZnIn2S4-STAB较ZnIn2S4-Blank,具有更高浓度的硫缺陷. 硫缺陷通过捕获电子促进了光生载流子的分离与利用,显著提高了ZnIn2S4-CTAB和ZnIn2S4-STAB的光催化甲苯选择性氧化制苯甲醛活性. 相似文献
35.
Jilong Li Yanhui Wang Rushuo Li Bowen Lu Yungang Yuan Hongwei Gao Shiwei Song Shuyu Zhou Jianbing Zang 《Electroanalysis》2021,33(10):2252-2259
A self-modified film electrode consisting of homogeneous snowflake-shaped nanoparticles on the amorphous carbon substrate (HNAC) was prepared by low temperature carbonization of phenolic resin. Such a unique structure was beneficial to enhance the electroanalysis signal responds. Simultaneous detection of DA and UA was performed on the HNAC using differential pulse voltammetry (DPV) at pH 8 phosphate buffer. The well-defined oxidation peak potential separation reached 260 mV between DA and UA. Meanwhile, the detection limit of HNAC were 0.401 μM (DA) and 2.800 μM (UA). 相似文献
36.
Photonic generation of a millimeter-wave signal based on sextuple-frequency multiplication 总被引:2,自引:0,他引:2
A millimeter-wave signal with sextuple-frequency multiplication of a microwave source is obtained with two cascaded optical modulators, which are driven by the same microwave source with phase deviation of pi/2 introduced by an electrical phase shifter. Without any optical filter, a wideband continuously tunable millimeter-wave signal is easily generated. 相似文献
37.
Synthesis of Site‐Specifically Phosphate‐Caged siRNAs and Evaluation of Their RNAi Activity and Stability 下载免费PDF全文
Dr. Li Wu Fen Pei Jinhao Zhang Junzhou Wu Mengke Feng Yuan Wang Dr. Hongwei Jin Prof. Liangren Zhang Prof. Xinjing Tang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(38):12114-12122
A complete set of new photolabile nucleoside phosphoramidites were synthesized, then site‐specifically incorporated into sense or antisense strands of siRNA for phosphate caging. Single caging modification was made along siRNA strands and their photomodulation of gene silencing were examined by using the firefly luciferase reporter gene. Several key phosphate positions were then identified. Furthermore, multiple caging modifications at these key positions led to significantly enhanced photomodulation of gene silencing activity, suggesting a synergistic effect. The caging group on both the terminally phosphate‐caged siRNA and the single‐stranded caged RNA has comparatively high stability, whereas hydrolysis of the caged group from the internally caged siRNA was observed, irrespective of the presence of Mg2+. Molecular dynamic simulations demonstrated that enhanced hydrolysis of the caging group on internally phosphate‐caged siRNAs was due to easy fragmentation of the caging group upon formation of the pentavalent intermediate of the phosphotriester with attack by water. The caging group in the terminally phosphate‐caged siRNA or single‐stranded caged RNA prefers to form π–π stacks with nearby nucleobases. In addition to providing explanations for previous observations, this study sheds further light on the design of caged oligonucleotides and indicates the direction of future development of nucleic acid drugs with phosphate modifications. 相似文献
38.
Lisheng Xu Guizhen Gao Cao Wengen Jigui Xu Liang Zhao Hongwei Shi Xingtao Zhang 《Applied biochemistry and biotechnology》2014,173(4):851-856
A new method for the synthesis of γ-glutamylmethylamide is presented. Glutamic acid γ-methyl ester was used as substrate for γ-glutamylmethylamide synthesis catalyzed by Escherichia coli with γ-glutamyltranspeptidase activity. Reaction conditions were optimized by using 300 mM glutamic acid γ-methyl ester and 3,000 mM methylamine at pH 10 and 40 °C. Bioconversion rate of γ-glutamylmethylamide reached 87 % after 10 h. γ-Glutamyltranspeptidase was reversibly inhibited only when glutamic acid γ-methyl ester was above 300 mM. 相似文献
39.
通过可控的方式精确调控纳米粒子的结构仍是一个富有挑战性和鼓舞人心的课题.尽管单原子或两、三个金属原子的精细调控已经在金纳米粒子中实现,涉及三个以上金属原子的取代(模块取代)还没有报道.本工作报道了环己硫醇配体保护的Au48(CHT)26的合成及其通过赝反伽伐尼过程的模块取代.单晶结构揭示模块取代的产物与母体团簇共用一个相似的Au31(CHT)12主体,但剩余部分不同(Au6(CHT)11 vs.Au16(CHT)14).一个有趣的发现是模块取代抑制了Au48(CHT)26的光热过程,却增强了它的发射,赋予了所合成团簇更好的双(多)功能应用潜力.光热效应的减弱和发射的增强也暗示了这两种作用能够彼此至少部分转化,对于研究这两种效应之间的相互影响也具有重要的启示. 相似文献
40.
B. Hari Babu Chengkun Lyu Hongwei Zhang Zhihao Chen Fenghong Li Lin Feng Xiao‐Tao Hao 《中国化学》2020,38(8):817-822
Interfacial engineering is expected to be a feasible strategy to improve the charge transport properties of the hole transport layer (HTL), which is of crucial importance to boost the device performance of organic solar cells (OSCs). In this study, two types of alcohol soluble materials, 2,3,5,6‐tetrafluoro‐7,7,8,8‐tetracyanoquinodimethane (F4‐TCNQ) and di‐tetrabutylammoniumcis–bis(isothiocyanato)bis (2,2’‐bipyridyl‐4,4’‐dicarboxylato) ruthenium(II) (N719) dye were selected as the dopant for HTL. The doping of F4‐TCNQ and N719 dye in poly (ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) with and without integrating a graphene quantum‐dots (G‐QDs) layer has been explored in poly[[2,6′‐4‐8‐di(5‐ethylhexylthienyl)benzo[1,2‐b:3,3‐b]dithiophene][3‐fluoro‐2[(2‐ethylhexyl)carbonyl]thieno[3,4‐b]thio‐phenediyl:(2,2′‐((2Z,2′Z)‐(((4,4,9, 9‐tetrakis(4‐hexylphenyl)‐4,9‐dihydro‐s‐indaceno[1,2‐b:5,6‐b′]dithiophene‐2,7‐diyl)bis(4‐((2‐ethylhexyl)oxy)thiophene‐5,2‐diyl))bis(methanylylidene))bis(5,6‐difluoro‐3‐oxo‐2,3‐dihydro‐1H‐indene‐2,1‐diylidene))dimalononitrile (PTB7‐Th:IEICO‐4F) OSCs. The power conversion efficiency of the non‐fullerene OSCs has been increased to 10.12% from 8.84%. The influence of HTL modification on the nano‐morphological structures and photophysical properties is analyzed based on the comparative studies performed on the control and modified devices. The use of chemical doping and bilayer strategy optimizes the energy level alignment, nanomorphology, hole mobility, and work‐function of HTL, leading to considerable reduction of the leakage current and recombination losses. Our work demonstrates that the doping of HTL and the incorporation of G‐QDs layer to constitute a bilayer HTL is an promising strategy to fabricate high performance non‐fullerene polymer solar cells 相似文献