ZnS量子点/聚氨酯纳米复合材料的荧光光谱研究

摘要：合成了高水溶性ZnS半导体量子点(QDs)及ZnS量子点/聚氨酯(PU)纳米复合材料。制备了用巯基丙酸(MPA)表面改性的ZnS量子点溶胶,再利用铸膜法得到了ZnS量子点/聚氨酯(PU)纳米复合膜。根据Brus模型和透射电镜分析可知,70 ºC下回流得到的ZnS量子点的尺寸为4-6 nm。荧光光谱表明,提高反应温度可显著提高ZnS量子点的发光强度;位于400 nm左右的发光带属于束缚态或受限态发光,而不是带边发光,这起因于束缚态载流子(电子和空穴)的辐射再结合; ZnS量子点/聚氨酯纳米复合材料的荧光光谱特性表明,复合材料中ZnS量子点的尺寸分布没有受到太大影响,不过发光带从400 nm蓝移到360 nm左右。     

通过静电作用组装CdSe/PDDA纳米复合膜

以巯基丙酸为稳定剂,用水相法合成了表面带负电荷的CASe半导体纳米晶．通过CASe纳米晶与阳离子聚电解质（聚二烯丙基二甲基氯化铵,PDDA）之间的静电相互作用,在经过预处理的带负电的石英基片表面组装多层CdSe／PDDA纳米复合膜．透射电镜（TEM）、紫外-可见光谱和荧光光谱研究结果表明,所得CdSe纳米晶粒径分布比较均匀,平均粒径约为5nm,且具有很高的荧光光致发光性．CdSe／PDDA纳米复合膜的紫外-可见吸收光谱中波长260nm和400nm处薄膜的吸光度与组装层数之间呈现良好的线性关系,表明所得的多层CdSe／PDDA纳米复合薄膜的成膜质量和稳定性良好．     

CdSe量子点的制备及其被聚乳酸包被的研究

以巯基乙酸为稳定剂,制备CdSe量子点,并考察聚乳酸对量子点的包被.采用透射电镜对CdSe量子点被聚乳酸包被前后的形貌进行观察,采用X射线粉末衍射、紫外可见吸收光谱、荧光光谱和荧光显微镜对产物进行分析和表征.研究结果表明:CdSe为闪锌矿型(立方形)的球形纳米晶,量子点的平均尺寸为4 nm,具有明显的量子尺寸效应和较强的荧光强度;组装聚乳酸的量子点相对于纯的量子点尺寸明显增大(40 nm),荧光强度有所增强,且量子点被包裹在内核,具有明显的核壳结构.     

半导体CdS/ZnS核壳结构纳米微粒的制备及光学特性

利用反胶团法合成CAS纳米微粒,并以ZnS对其进行表面修饰,得到具有CdS/ZnS包覆结构的纳米微粒,以紫外-可见吸收光谱(UV)证实了CdS/ZnS核壳结构的实现并表征其光学特征.透射电镜(TEM)表征其粒度和形貌,得到CAS/ZnS包覆结构粒径一般在2-3nm.通过陈化实验发现粒径随时间变化不大.     

还原性巯基修饰的 CdSe/ZnS 量子点合成及其与人血清白蛋白相互作用的研究

以还原型谷光苷肽为修饰剂,在水相中合成了稳定的核壳结构的 CdSe /ZnS 量子点．采用紫外-可见吸收光谱和荧光光谱研究其与人血清白蛋白（HSA）的相互作用,研究表明：CdSe /ZnS 量子点对 HSA 内源荧光的猝灭机制属于形成复合物引起的静态猝灭,28℃时猝灭常数为2．1＆#215;105 Lmol -1,结合常数为2．8＆#215;105,结合位点数为1．0,量子点与 HSA 的结合力为静电作用力,量子点对 HSA 的构型未改变．     

水热法合成荧光碳量子点及其对Fe(Ⅲ)的专一识别

以天然物质银杏果为反应起始物,一步水热法快速合成荧光碳量子点,通过透射电镜、红外光谱、X-射线光电子能谱、紫外可见光吸收光谱以及荧光光谱对其进行表征,得出合成的碳量子点具有准球形且尺寸小于10nm,表面上含有羟基及羧基等亲水基团,紫外最大吸收在280nm处,荧光的发射波长具有激发波长依赖性且最强发射波长在425nm。合成的碳量子点具有很好的光学稳定性。在与金属离子作用实验中得出碳量子点对Fe~(3+)具有很好的专一识别,且在1.0~20μmol/L有良好的线性相关性,检出限为0.18μmol/L,可开发作为一种新型的优良Fe~(3+)传感器。     

Mn/ZnS量子点的制备及表征

为了得到晶型稳定、荧光性可控的Mn/ZnS量子点,用锰、锌、硫的盐溶液进行制备,以X射线衍射、原子吸收光谱、荧光光谱、原子力显微镜扫描等手段进行了表征.利用原子力显微镜可以观察量子点的形貌及分布情况,并能鉴别出Mn2+特殊的形貌结构.结果表明,不同锌硫比条件下的晶面取向稳定,并且锰离子成功掺入了ZnS晶格.不同锌硫比导致发光强度有所不同,在锌硫比为1∶1时,Mn/ZnS发光强度最大.该方法制备出的Mn/ZnS量子点晶型稳定,并且具有可控的荧光性.     

尿素还原法制备碳量子点

将富勒烯C_(60)和C_(70)分别在空气气氛中350℃下煅烧,然后采用尿素还原法在温和(90℃)条件下制备得到碳量子点;以透射电子显微镜、粉末X-射线衍射、拉曼光谱和傅里叶变换红外光谱等对碳量子点的组成和形貌进行表征,通过紫外-可见吸收光谱和荧光光谱对其光学性能进行研究;并推测碳量子点的形成机制.结果表明,在激发光波长为320nm时,两种碳量子点的荧光最大发射峰波长位于450nm附近,相对荧光量子产率分别为23.24%和27.55%,推测其形成机制为尿素对空气气氛中煅烧过的富勒烯表面氧化位点的还原.该结果为温和条件下合成碳量子点提供了一种新的思路.     

CdSe:Zn/ZnS核壳量子点的化学合成及光谱性质研究

采用绿色合成工艺,使用多种配体分别在水溶液中合成了水溶性的CdSe:Zn/ZnS核壳量子点,并通过多种测试手段对产物的结构及光谱性质进行讨论.XRD结果表明,合成的CdSe:Zn/ZnS核壳量子点为立方闪锌矿结构,产物的平均晶粒尺寸约为2.4nm,相比未加配体得到的量子点的晶粒要小一些.SEM图像表明合成的样品为近球形颗粒.有趣的是,合成的样品具有良好的的亲水性,推断样品的表面包覆有亲水性基团,该推断与FT-IR结果相吻合.量子点的吸收峰位与相应的体材料相比,均产生明显的蓝移,展示出明显的量子限域效应.     

ZnSe/5B2O3-95SiO2纳米复合材料的制备及性能表征

采用溶胶凝胶工艺在室温合成合有Zn、Se成分和玻璃相成分的均匀透明凝胶，并通过CO还原气氛热处理，在凝胶玻璃中原位生长出ZnSe纳米晶体．利用BET比表面积、透射电镜、吸收光谱、荧光光谱等分析手段对ZnSe纳米复合材料的组成结构及量子尺寸效应影响下的光学性能进行了表征，结果表明：5B2O3—95SiO2凝胶玻璃的多孔结构可有效地分散ZnSe纳米晶粒；纳米复合材料中ZnSe纳米晶粒呈球形，粒径约为3．5nm；吸收光谱中，ZnSe纳米复合材料的吸收边相对于ZnSe体材料发生蓝移，随着ZnSe在凝胶玻璃中摩尔分数的增大，蓝移量减小，相应ZnSe纳米晶粒尺寸增大；在荧光光谱中，500nm附近的发光带是凝胶玻璃中的ZnSe纳米晶体表面态复合和缺陷发光，当ZnSe的摩尔分数达到0．07时，观测到了浓度的荧光淬灭现象．     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

海南岛地体及其毗邻陆缘晚中生代—新生代古地磁研究和构造演化

本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。     

《Chinese Science Bulletin》SUBJECT INDEX TO VOLUME 59(2014)

正~~     

Achieving Unusual States of Matter Under High Pressure

The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to     

Exciton Seebeck in Molecular Systems

Various applications relevant to the exciton dynamics,such as the organic solar cell,the large-area organic light-emitting diodes and the thermoelectricity,are operating under temperature gradient.The potential abnormal behavior of the exicton dynamics driven by the temperature difference may affect the efficiency and performance of the corresponding devices.In the above situations,the exciton dynamics under temperature difference is mixed with