Sequential Growth of Cs_(3)Bi_(2)I_(9)/BiVO_(4)Direct Z-Scheme Heterojunction for Visible-Light-Driven Photocatalytic CO_(2)Reduction

The high exciton binding energy and lack of a positive oxidation band potential restrict the photocatalytic CO_(2)reduction efficiency of lead-free Bi-based halide perovskites Cs_(3)Bi_(2)X_(9)(X=Br,I).In this study,a sequential growth method is presented to prepare a visible-light-driven(λ>420 nm)Z-scheme heterojunction photocatalyst composed of BiVO_(4)nanocrystals decorated on a Cs_(3)Bi_(2)I_(9)nanosheet for photocatalytic CO_(2)reduction coupled with water oxidation.The Cs_(3)Bi_(2)I_(9)/BiVO_(4)Z-scheme heterojunction photocatalyst is stable in the gas-solid photocatalytic CO_(2)reduction system,demonstrating a high visible-light-driven photocatalytic CO_(2)-to-CO production rate of 17.5μmol/(g·h),which is approximately three times that of pristine Cs_(3)Bi_(2)I_(9).The high efficiency of the Cs_(3)Bi_(2)I_(9)/BiVO_(4)heterojunction was attributed to the improved charge separation in Cs_(3)Bi_(2)I_(9).Moreover,the Z-scheme charge-transfer pathway preserves the negative reduction potential of Cs_(3)Bi_(2)I_(9)and the positive oxidation potential of BiVO_()4.This study off ers solid evidence of constructing Z-scheme heterojunctions to improve the photocatalytic performance of lead-free halide perovskites and would inspire more ideas for developing leadfree halide perovskite photocatalysts.

ZnO-chitosan/Rectorite Nanocomposite Exhibiting High Photocatalytic Activities under Visible-light Irradiation

Chitosan(CS),hydrated zinc acetate,and rectorite(REC) were used as raw materials to prepare CS-embedded zinc oxide(ZnO) nanoparticle by a chemical precipitation process.Hydrogen-bonded REC-loaded ZnO-CS nanoparticle was to form ZnO-CS/REC nanocomposite photocatalyst,its morphology and structure were analyzed by means of FTIR,XRD,TGA,SEM,and TEM.The effects of the catalyst dosage,methyl orange(MO) initial concentration and solution pH on photocatalytic performance were also discussed.The experimental results show that the ZnO-CS/REC nanocomposite has a particle size of 100 nm with good dispersion and uniformity.Under irradiation of visible light,0.6 g/L photocatalyst was used to degrade MO in solution for 90 min at pH 6,then the MO solution(10 mg/L) was decolored by more than 99%,indicating that the ZnO-CS/REC nanocomposite exhibited highly photocatalytic degradation activity.Therefore,the photodegradation kinetic mechanism of MO in aqueous solution is presumed.

In-situ hydrothermal synthesized γ-Al_2O_3/O-g-C_3N_4 heterojunctions with enhanced visible-light photocatalytic activity in water splitting for hydrogen

In this work,γ-Al_2O_3 and hydrogen peroxide treated g-C_3N_4(O-g-C_3N_4) were combined through a novel in-situ hydrothermal method to form heterojunction structured photocatalysts.These photocatalysts were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),Fourier transform infrared spectroscopy(FT-IR),X-ray photoelectron spectroscopy(XPS),UV–vis diffuse reflectance spectroscopy and photoluminescence spectroscopy(PL).FT-IR results indicate that oxygen functional groups can be grafted on the surface of O-g-C_3N_4 by hydrogen peroxide treatment.The visible light photocatalytic hydrogen evolution rate was investigated in 10 vol% TEOA aqueous solution.The optimal Al_2O_3 mass content is set to be 20 wt% and the corresponding hydrogen evolution rate is 1288 μmol/h/g which is approximately 6,3 folds that of pristine g-C_3N_4 and O-g-C_3N_4 respectively and 1.6 folds that of mechanical mixed composite with the same Al_2O_3 mass content.The photocurrent density–time curves were carried out under visible light illumination for four on–off cycles.The electrochemical impedance spectroscopy(EIS) measurements verified the enhanced separation efficiency of electron–hole pairs.This work raised a new method to form the heterojunction structured photocatalysts and achieved a remarkable improvement of the photocatalytic activity in water splitting for hydrogen under visible light irradiation.

LED Modulation Characteristics in a Visible-Light Communication System

This paper conducts a research on modulation characteristics of blue light-emitting diodes (LEDs) used in a visible-light communication (VLC) system. Through analysis of the modulation characteristics of LEDs with different emitting sizes, we find that there is a similar linear relationship between LED’s 3dB bandwidth and the operation current density. This experiment also shows that high series resistance is one major issue that limits our LED's modulation speed. To further improve the LED bandwidth, the resistance can be reduced by optimizing device layout as well as reducing material bulk resistance. Clearly, this study provides an approach to increase the modulation bandwidth of GaN-based LEDs for VLC systems.

A COMPARATIVE STUDY OF DNA FLOW CYTOMETRY AND MICROSPECTROPHOTOMETRY IN GASTRIC CARCINOMAS

Flow cytometric (FCM) and microspectrophotometric (MSP) measurements of cell nuclear DNA content were made in 53 fresh gastric carcinoma specimens and in 30 gastric mucosal specimens with chronic gastritis. DNA aneuploidy was found in 32/53 (60%) of gastric carcinomas, and appeared more frequently in wellor moderately differentiated tubular adenocarcinomas (90%) than in undifferentiated and mucousa cell carcinomas (23.6%) (P【0.001). No aneuploidy was found in chronic gastritis samples, but their proliferative cell fractions were higher than in normal control gastric mucosa samples (P【0.01). A comparison was made between FCM and MSP analyses of DNA content in 29 cases of gastric carcinoma, a high correlation rate (r=0.90) was found. The advantages and limitations of both methods are discussed, they may be used in combination for more precise cytochemical analysis.

Visible-light all-fiber vortex lasers based on mode selective couplers

We demonstrate visible-light all-fiber vortex lasers by incorporating the home-made mode selective couplers (MSCs). The MSC at green or red wavebands is fabricated by specially designing and fusing a single-mode fiber (SMF) and a few-mode fiber (FMF). The MSCs inserted into visible fiber cavities act as power splitters and mode converters from the LP01 to LP11 mode at green and red wavelengths, respectively. The red-light all-fiber vortex laser is formed by a 10-cm Pr3+/Yb3+:ZBLAN fiber, a fiber Bragg grating, a fiber end-facet mirror and the MSC at 635 nm, which generates vortex beams with OAM±1 at 634.4 nm and an output power of 13 mW. The green-light all-fiber vortex laser consists of a 12-cm Ho3+:ZBLAN fiber, two fiber pigtail mirrors, and the MSC at 550 nm, which generates vortex beams with OAM±1 at 548.9 nm and an output power of 3 mW.

A Novel Visible-light-responsive Photocatalyst Bi1.5Cr0.5WO6 with Suitable Bandgap Structure and Its Application in Water Decontamination

Integrating the advantages of Bi and Cr elements in the bandgap engineering of metal oxides, a visible-light-responsive photocatalyst Bi1.5Cr0.5WO6 is successfully constructed and initially applied in water decontamination. The combination of UV-vis diffuses reflectance and the Mott-Schottky curve from electrochemical testing can be used to determine the conduction band and valence band of Bi1.5Cr0.5WO6 to be about –1.26 and 1.42 V, respectively. The location of energy band structure indicates that the superoxide free radical can be produced in Bi1.5Cr0.5WO6 photocatalytic system without hydroxyl group. This speculation is also confirmed by ESR experiment and active radical species scavenging experiments. In addition, the best photocatalytic performance of Bi1.5Cr0.5WO6 obtained under 180 ℃ is attributed to the smallest impedance and the strongest electronic migration capability.

Rare Earth Ion Yb^3+ Doping of Bi2WO6 with Excellent Visible-light Photocatalytic Activity

The rare earth ion Yb^3+ doped Bi2WO6 photocatalysts were synthesized by hydrothermal method.Moreover,XRD,XPS,FESEM,TEM,Ramam,N2 adsorption-desorption isotherm measurements and UV-vis diffusion reflectance spectra were used to characterize the Yb^3+ doped Bi2WO6 photocatalysts.The morphology,specific surface area,and pore volume distribution were greatly affected after Yb3+ ions doping.Photocatalytic performance of Bi2WO6 was effectively enhanced after Yb3+ ions doping,6% Yb^3+ doped Bi2WO6 had the best photocatalytic performance,and 96.2% Rhodamine B was degradated after irradiated 30 min,which was 1.29 times that of the pristine one.The enhanced photocatalytic performance was due to the increased specific surface area,decreased energy band gap and inhibition of photoelectron-hole recombination after Yb3+ ions doping.

Preparation of Novel Mesoporous Photocatalyst Bi₄O₅Br₂/SBA-15 with Enhanced Visible-Light Catalytic Activity

Photocatalysis is one of the most promising methods owing to its great potential to relieve environmental issue. To construct efficient photocatalyst with low energy consumption, mild catalytic conditions, and stable chemical properties are highly desired. In this work, a novel, highly active and environmental friendly mesoporous photocatalyst Bi4O5Br2/SBA-15 was synthesized by hydrothermal method, and its characteristics and visible-light catalytic activity were investigated. The synthesized photocatalyst consisted of Langmuir type IV hysteresis loops, which was confirmed to be a composite material with mesoporous structure. It exhibited a high visible-light absorption intensity and a low recombination rate of photo-generated electrons and holes. When the mass ratio of Bi/SiO2 was 30/100 during the synthesis, the obtained photocatalyst (Bi30/SBA-15) reflected the fastest Rhodamine B (RhB) removal rate and achieved 100% decolorization of RhB by both adsorption and degradation process. This high decolorization efficiency can also be maintained and realized by recycling the used composite in practice. The enhanced visible-light photocatalytic activity of novel Bi4O5Br2/SBA-15 photocatalyst can be ascribed to the existing active sites both inside and outside SBA-15 which enhanced the separation of photo-generated electrons and holes.

Enhanced visible-light photocatalytic hydrogen evolution using two-dimensional carbon nitride sheets with the removal of amine groups

Two-dimensional(2D)carbon nitride sheets(CNs)with atomically thin structures are regarded as one of the most promising materials for solar energy conversion.However,due to their substantially enlarged bandgap caused by the strong quantum size effect and their incomplete polymerisation with a large number of non-condensed surface amino groups,the practical applicability of CNs in photocatalysis is limited.In this study,CNs with broad visible-light absorption were synthesised using a 5-min fast thermal annealing.The removal of uncondensed amine groups reduces the bandgap of CNs from 3.06 eV to 2.60 eV,increasing their absorption of visible light.Interestingly,the CNs were distorted after annealing,which can differentiate the spatial positions of electrons and holes,enhancing the visible-light absorption efficiency.As a result,when exposed to visible light,the photocatalytic hydrogen production activity of atomically thin 2D CNs rose by 8.38 times.This research presents a dependable and speedy method for creating highly effective visible-light photocatalysts with narrowed bandgaps and improved visible-light absorption.

Additive-free synthesis of S-substituted isothioureas via visible-light-induced four-component reaction ofα-diazoesters,aryl isothiocyanates,amines and cyclic ethers

An additive-free and environmentally friendly strategy has been realized for the construction of S-substituted isothioureas through visible-light-induced multicomponent reaction starting fromα-diazoesters,aryl isothiocyanates,amines and cyclic ethers.This methodology features simple operation,mild reaction conditions,favorable functional group tolerance,easily available starting materials and high efficiency.

Continuous microflow visible-light photocatalytic N-formylation of piperidine and its kinetic study

N-formylation of amines,a class of synthetically important reactions,is typically conducted using metal catalysts that are relatively expensive or not readily available and usually needs harsh conditions to increase the reaction efficiency.Here,an efficient continuous microflow strategy was developed for the gas-liquid visible-light photocatalytic N-formylation of piperidine,which achieved a reaction yield of 82.97%and a selectivity of>99%at 12 min using cheap organic dye photocatalyst under mild reaction conditions.The influence of essential parameters,including light intensity,temperature and equivalents of the gas,additive and photocatalyst,on the reaction yield was systematically studied.Furthermore,kinetic investigations were conducted,exhibiting the dependence of reaction rate and equilibrium yield of N-formylpiperidine on light intensity,temperature and photocatalyst equivalent.The microflow photocatalytic approach established in this work,which realized a markedly higher space-time yield than the conventional batch method(37.9 vs.0.212 mmol h-1 L-1),paves the way for the continuous,green and efficient synthesis of N-formamides.

虚寒薄白苔的细胞化学初步研究

本研究首次运用细胞化学定位定性定量技术对25例虚寒证患者的薄白舌苔与20例正常淡红舌薄白苔舌上皮细胞中的脱氧核糖核酸(DNA)、糖原(PAS)、琥珀酸脱氨酶(SDH)、酸性α-醋酸萘酯酶(ANAE)等化学成分进行对比观察,发现虚寒薄白苔舌上皮细胞中的PAS、DNA高于正常薄白苔(P<0.001,P<0.05),而SDH、ANAE活性显著低于正常薄白苔(P<0.001,P<0.01),并初步探讨了正常薄白苔的细胞化学特点及虚寒薄白苔的变化机制。

对几种百合科植物基因组大小的评价

利用孚尔根显微分光光度法测定了洋葱（ＡｌｌｉｕｍｃｅｐａＬ．）、头（Ａ．ｃｈｉｎｅｓｅＧ．Ｄｏｎ，）、分葱（Ａ．ａｓｃａｌｏｎｉｕｍＬ．）和黄花（ＨｅｍｅｒｏｃａｌｌｉｓｃｉｔｒｉｎａＢａｒｏｎｉ）４种百合科植物根尖的细胞核ＤＮＡ含量，并根据各自的核型得出了每个物种的基因组大小。它们分别为：洋葱１８．１６×１０９ｂｐ、头１２．８４×１０９ｂｐ、分葱１０．４４×ｌ０９ｂｐ和黄花７．４８×１０９ｂｐ。由此认为，基因组是生物体维持其生存所需的全套基因。它反映了生物物种全部的、特定的遗传信息。与胞核ＤＮＡ含量相比较，基因组大小更适合作为生物研究的特征参数。这不仅对细胞学、分类学和遗传学，而且对分子生物学亦有一定的意义。

茶秆竹细胞壁解剖特性以及木质素微区分布

对12个月的茶秆竹进行细胞壁解剖特性和木质素微区分布的研究,运用光学显微镜、激光共聚焦扫描显微镜以及颜色反应鉴定木质素的存在,利用组织化学染色方法及其可见光显微分光光度计半定量测定竹材纤维、薄壁组织和导管细胞壁各微区的木质素含量。12个月时细胞壁全部木质化,木质素在各组织中均有分布,其含量因组织类型及其细胞壁微区不同而有差异。从组织化学染色及可见光吸收光谱图的吸收峰值,说明细胞壁各微区中存在愈创木基(G)和紫丁香基(S)2种木质素组成单元。竹壁径向和纤维帽不同位置的木质素含量未有明显的规律性变化。纤维次生壁具有薄厚层交替的多层结构,薄层木质素含量大于厚层。

正常人及不育者精子核DNA的定量研究

用流式细胞术,Feulgen显微分光光度法,荧光显微分光光度法测定正常人精子核DNA相对含量:结果表明,上述方法所测得的精子核DNA相对含量稳定,变化范围小。同时用Feulgen显微分光光度法测定不育者精子核DNA相对含量。显示不育者精子核DNA相对含量高于正常人,提示精子核DNA核蛋白复合物异常可能是某些男性不育症的原因。此项研究为诊断男性不育症提供了新方法,在男性学精子核分子研究方面提供了依据。

竹材木质素在细胞壁中的微区分布

对12个月的毛竹和茶秆竹进行了木质素微区分布的研究,实验运用光学显微镜和激光共聚焦扫描显微镜鉴定了木质素的存在,并且利用组织化学染色方法及其可见光显微分光光度计半定量测定竹材纤维?薄壁组织和导管的细胞壁各微区木质素含量。毛竹竹茎各组织细胞壁各微区的木质素含量均大于茶秆竹相应部位的。木质素在各组织中均有分布,其含量因组织类型及其细胞壁不同微区而有差异,其结构中存在愈创木基(G)和紫丁香基(S)两种木质素组成单元。竹壁径向和纤维帽不同位置的木质素含量未有明显的规律性变化。纤维次生壁具有薄厚层交替的多层结构,薄层的木质素含量大于厚层的。

可见光显微分光光度法测定毛竹发育过程中木素微区分布

运用光学显微镜和可见光显微分光光度计以及组织化学染色对毛竹发育过程中的木质素微区分布进行了研究。木质素在各组织中均有分布,其含量因竹龄,组织及细胞壁微区不同而有差异。细胞壁各微区中存在愈创木基(G)和紫丁香基(S)两种木质素组成单元。纤维次生壁,细胞角隅区和复合胞间层的木质素含量12个月内逐渐增加,而后变化较小,但是各微区的木质化速率因竹龄变化而变化。同一竹龄竹壁径向和纤维帽不同位置的木质素含量未有明显的规律性变化。薄壁组织次生壁,胞间层以及导管次生壁在12个月内木质化程度不断加强,而后变化较小。

自制显微荧光光度系统及其应用

用自行开发的细胞显微荧光分光光度系统对神经细胞内游离的静息[Ca^(2+)]_j及其动态生理变化成功地进行了测定,实验结果证明系统工作稳定、重复性好,测定结果也符合公认的动态变化特点。本文报道了该项研究工作开发成功的细胞显微荧光光度系统及神经细胞内钙离子的分析测定过程及其结果。

书写材料的无损检验系统研究

本研究运用显微分光光度仪、文件检验仪和傅立叶变换拉曼光谱仪三种方法,分别对在中国市场上收集的不同厂家、牌号、型号的35种黑墨水、20种蓝黑墨水、22种蓝墨水、49种黑色墨水笔、30种蓝色墨水笔、45种黑色圆珠笔、和50种蓝色圆珠笔等七组样品进行非破坏检验。结果表明:(1三种非破坏检验方法都能单独对七组样品进行不同程度的鉴别,区分率在50%—94.4%之间;(2)三种方法联用后对黑墨水、蓝黑墨水、蓝墨水、黑色墨水笔、蓝色墨水笔、黑色圆珠笔和蓝色圆珠笔的区分率可分别提高到93.4%、97.3%、99.1%97.2%、97.2%、95.6%和91.8%。通过三种非破坏检验方法的联用,证明它们之间有较强的互补性,最大限度地提高了检验效应,可建立系统的非破坏检验方法。