ZnO纳米片组装的微球和层状集聚体的控制合成及其发光性质

通过锌片与水分别在乙二醇和乙二胺中120 ℃反应12 h,直接在锌片上原位合成出ZnO纳米片组装的微球和层状集聚体。利用X射线粉末衍射、扫描电子显微镜、透射电子显微镜和红外光谱对产物进行了表征和分析。结果表明,在乙二醇中得到的直径为0.3～2 µmZnO微球是由直径为30～50 nm纤锌矿结构的ZnO纳米片通过氢键组装而成;在乙二胺中得到的层状集聚体是由20～30 nm的纤锌矿结构的ZnO纳米片通过氢键组装成尺寸约为450×900 nm纳米片,这些较大尺寸纳米片再通过范德华力组装而成。研究了乙二醇和乙二胺在ZnO微球和层状集聚体形成过程中的作用并提出了可能的生长机理。在波长为300 nm光的激发下,发现ZnO微球和层状集聚体具有发光峰位于397 nm强的紫外光发光、485和520 nm弱的蓝绿光发光,它们分别起源于ZnO宽带隙的激子发射,氧空位与间隙氧之间的跃迁以及表面上离子化氧空位中的电子与价带中光激发的空穴之间的复合。     

ZnO纳米片组装的微球和层状集聚体的控制合成及其发光性质

通过锌片与水分别在乙二醇和乙二胺中120 ℃反应12 h,直接在锌片上原位合成出ZnO纳米片组装的微球和层状集聚体。利用X射线粉末衍射、扫描电子显微镜、透射电子显微镜和红外光谱对产物进行了表征和分析。结果表明,在乙二醇中得到的直径为0.3～2 µmZnO微球是由直径为30～50 nm纤锌矿结构的ZnO纳米片通过氢键组装而成;在乙二胺中得到的层状集聚体是由20～30 nm的纤锌矿结构的ZnO纳米片通过氢键组装成尺寸约为450×900 nm纳米片,这些较大尺寸纳米片再通过范德华力组装而成。研究了乙二醇和乙二胺在ZnO微球和层状集聚体形成过程中的作用并提出了可能的生长机理。在波长为300 nm光的激发下,发现ZnO微球和层状集聚体具有发光峰位于397 nm强的紫外光发光、485和520 nm弱的蓝绿光发光,它们分别起源于ZnO宽带隙的激子发射,氧空位与间隙氧之间的跃迁以及表面上离子化氧空位中的电子与价带中光激发的空穴之间的复合。     

ZnO纳米片自组装空心微球的无模板水热法制备与发光性质

报道了一种简单的制备ZnO纳米片自组装成空心微球的无模板水热法. 即通过醋酸锌与水和乙二醇混合溶剂(V_水/V_乙二醇 = 1/20)在100℃水热反应12 h合成了ZnO空心微球. 利用扫描电子显微镜、透射电子显微镜、X 射线衍射仪和红外光谱对产物进行了表征和分析. 结果表明, 所制备ZnO空心微球的直径为2~5 μm, 它是由直径为10~20 nm纤锌矿结构的ZnO纳米片自组装而成. 研究了水与乙二醇的体积比及反应时间对产物形貌的影响, 结果表明乙二醇在ZnO纳米片的形成与自组装过程中起着关键作用, 并提出了可能的生长机理. 在波长为300 nm光的激发下, 发现ZnO空心微球具有发光峰位于397 nm强的紫外光发光和486 nm弱的蓝绿光发光, 这两种发光分别起源于ZnO宽带隙的激子发射和氧空位与间隙氧之间的跃迁.     

加热覆盖有ZnCl2溶液的锌片制备ZnO亚微米棒阵列

将表面覆盖有ZnCl2溶液的锌片加热到400 ℃反应1 h, 在锌片上生长出了ZnO亚微米棒阵列. 采用扫描电镜、透射电子显微镜和X射线衍射仪对所制备的产物进行了表征和分析. 结果表明产物为六方相纤锌矿单晶结构的ZnO亚微米棒, 其直径和长度分别为300～650 nm和6 μm, 提出了ZnO亚微米棒可能的生长机理. 在波长为300 nm光的激发下, 发现了ZnO亚微米棒阵列具有发光峰位于395 nm强的紫外光发光和位于490 nm弱的蓝绿光发光, 这两种发光分别起源于ZnO宽带隙带边发射和ZnO中相应的缺陷结构.     

杨桃状ZnO纳米片微球的制备及气敏性能的研究

以六水合硝酸锌和尿素为原料,水为反应介质,油酸作为表面活性剂,经水热过程合成了由纳米片组装的碱式碳酸锌微球前驱体,经煅烧后得到形貌一致的氧化锌(ZnO)纳米片组装的杨桃状微球。采用X射线衍射仪(XRD)和环境扫描电镜(SEM)对样品进行表征,结果表明产物为六方纤维矿结构的ZnO,微球尺寸比较均一,直径约为20μm,组装单元扇形ZnO纳米片均匀排列,单元之间存在均匀空隙,BET测试显示纳米片呈现多级介孔结孔结构,比表面积为18.9m2·g-1,室温下的光致发光性能表明其结构表面存在大量氧空位,对产物ZnO气敏元件进行了乙醇和丙酮气体敏感性测试。     

纳米ZnO的阳极消耗法制备和表征

采用阳极消耗法制备了纳米ZnO粉体,并利用XRD,TEM,XPS,UV-V is和PL测试技术对样品进行了表征.结果表明,所制样品为纤锌矿结构的纳米ZnO,颗粒呈类球形,平均粒径15 nm,具有很强的紫外吸收能力.位于531.44 eV的O1 s峰和PL谱上的绿带共同证明了氧空位存在,纳米ZnO的绿光发射带来自氧空位电子与价带空穴的辐射复合.     

图案化锥形氧化锌纳米带的原位热氧化法制备与发光性质

采用光刻技术制备出图案的锌膜,所得锌膜与纯氧在700℃氧化反应10 min,在锌膜的表面上原位生长出具有图案的锥形ZnO纳米带阵列,实现了ZnO纳米带生长位置的可控生长。锌膜上得到的锥形ZnO纳米带为单晶六方纤锌矿结构,长度在1～4μm,纳米带根部和顶部的宽度分别在300～700 nm和100～300 nm。提出了锥形ZnO纳米带的可能生长机理。在波长为300nm光的激发下,发现了锌膜上锥形ZnO纳米带具有发光峰位于395 nm弱的紫外光发光和510 nm强的蓝绿光发光,它们分别起源于ZnO宽带隙的激子发射以及表面上离子化氧空位中的电子与价带中光激发的空穴之间的复合。     

超声化学合成多角星形氧化锌

室温下将乙酸锌和三乙胺的水溶液超声辐照30 min,制得三维的多角星形半导体ZnO微晶。粉体用XRD、FESEM、TEM和EDS进行了表征。结果表明：粉体ZnO为六方纤锌矿相结构的多角星形微晶,星形结构由纳米锥组装而成,纳米锥由微小的纳米粒子构筑而成。改变超声时间和三乙胺浓度的对比实验跟踪了晶体的生长过程,分析了可能的反应机理。粉体室温下的PL表明在387nm处有一弱的紫外发射峰,在561 nm处出现强且宽的黄色发光带,黄光是与间隙氧(填隙氧)有关的深能级缺陷发光引起的。     

纳米ZnO脱硫剂表面结构与室温脱除H2S性能的研究

采用均匀沉淀法制备纳米ZnO，经260 ℃，360 ℃，460 ℃和550 ℃焙烧制备的纳米ZnO均具有六方纤锌矿结构，平均粒径分别为14.3 nm，21.2 nm，24.1 nm和35.3 nm。通过TEM、TPR、XRD和XPS等技术对脱硫剂进行了表征。结果表明，纳米ZnO提高了对H₂S的室温去除率，室温脱除H₂S的活性时间是分析纯ZnO的近40倍；其脱硫性能随粒径增大，氧空位减少而下降，脱硫后高结合能的硫物种增多，硫取代晶格氧的趋势增大。说明粒径大小和氧空位是纳米ZnO室温脱硫的主要影响因素。纳米ZnO(14.3 nm)可直接将H₂S选择氧化为单质硫，尾气中未见SO₂产生。     

Sn掺杂ZnO纳米针的结构及其生长机制(英文)

利用包括磁控溅射和热氧化的两步法在Si(111)衬底上制备了Sn掺杂ZnO纳米针.首先用磁控溅射法在Si(111)衬底上制备Sn:Zn薄膜,然后在650℃的Ar气氛中对薄膜进行热氧化,制备出Sn掺杂ZnO纳米针.样品的结构、成分和光学性质采用X射线衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、高分辨透射电子显微镜(HRTEM)、能量散射X射线(EDX)谱和光致发光(PL)光谱等技术手段进行分析.结果表明,制备的样品为具有六方纤锌矿结构的单晶Sn掺杂ZnO纳米针,Sn掺杂量为2.5%(x,原子比),底部和头部直径分别为200-500 nm和40 nm,长度为1-3μm,结晶质量较高.室温光致发光光谱显示紫外发光峰比纯ZnO的发光峰稍有蓝移,这可归因于能谱分析中探测到的Sn的影响.基于本实验的实际条件,简单探讨了Sn掺杂ZnO纳米针的生长机制.     

Furyl- and thienyl-silatranes and germatranes

We review our research on the synthesis and study of the physical and biological properties of furyl- and thienylgermatranes and -silatranes.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 725–732, June, 1992.     

Review and patents and literature

The use of the insect cell/baculovirus expression system for producing recombinant proteins of bacterial, plant, insect, and mammalian origin has become widespread. The popularity of this eukaryotic expression system is due to many factors, including (1) potentially high protein expression levels, (2) ease and speed of genetic engineering, (3) ability to accommodate large DNA inserts, (4) protein processing similar to higher eukaryotic cells (e.g., mammalian cells), and (5) ease of insect cell growth (e.g., suspension growth). The following review of the literature discusses two engineering aspects of recombinant protein synthesis by insect cell cultures: bioreactor scale-up and insect cell line selection. Following this review patent abstracts and additional literature pertaining to expression of recombinant proteins in insect cell culture are listed.     

多环芳二酐型聚酯亚胺膜的透气性能

多环芳二酐型聚酯亚胺膜的透气性能李悦生，丁孟贤，徐纪平（浙江大学高分子科学与工程研究所，杭州，３１００２７）（中国科学院长春应用化学研究所）关键词聚醚酰亚胺，聚酯酰亚胺，膜，透气性通常的聚酰亚胺加工性能较差，在芳环二酐的苯环间引入醚键等柔性基团后，其...     

Hard and soft acids and bases: structure and process

Under investigation is the structure and process that gives rise to hard-soft behavior in simple anionic atomic bases. That for simple atomic bases the chemical hardness is expected to be the only extrinsic component of acid-base strength, has been substantiated in the current study. A thermochemically based operational scale of chemical hardness was used to identify the structure within anionic atomic bases that is responsible for chemical hardness. The base's responding electrons have been identified as the structure, and the relaxation that occurs during charge transfer has been identified as the process giving rise to hard-soft behavior. This is in contrast the commonly accepted explanations that attribute hard-soft behavior to varying degrees of electrostatic and covalent contributions to the acid-base interaction. The ability of the atomic ion's responding electrons to cause hard-soft behavior has been assessed by examining the correlation of the estimated relaxation energies of the responding electrons with the operational chemical hardness. It has been demonstrated that the responding electrons are able to give rise to hard-soft behavior in simple anionic bases.     

微量元素与疾病诊断治疗的研究现状及展望

对国内外微量元素与疾病的关系及其诊断治疗的研究现状及研究动向进行了综述，包括：微量元素与地方病、癌肿、心血管病、糖尿病、眼病、神经系统病等。参考文献72篇。     

Preparation and photolysis of poly-p-ethylacrylophenone and poly-p-chloroacrylophenone and their copolymers with styrene and methyl methacrylate

Poly-p-ethylacrylophenone (PPEtAP) and poly-p-chloroacrylophenone (PPClAP) and their copolymers with styrene (PEtAP/S) and (PClAP/S) and with methyl methacrylate (PEtAP/MMA) and (PClAP/MMA) were prepared. Quantum yields of main-chain scissions at 366 nm at room temperature in benzene solution are of the same order as those of the unsubstituted polyacrylophenone and its copolymers. Substitution with chlorine and ethyl group in the para position compared to the unsubstituted polyacrylophenone and its copolymers leads to an increase of the lifetime for the n–π^* excited triplet state, as is evident from the measured quenching constants of photolysis. The low-temperature emission spectra of the copolymers are similar to the spectra of the model compounds in a polymer film. For the homopolymer, however, the character of the emission spectrum changes considerably.     

Concentrations and distributions of trace and minor elements in Chinese and Canadian coals and ashes

A total of 35 trace and minor elements including some of environmental significance were determined in each of a selection of 15 Chinese and 6 Canadian thermal coals and their ashes by using the SLOWPOKE-2 nuclear reactor facility of the University of Toronto. The concentrations and distributions of these constituents among the coals and their combustion products (viz. ash and volatile matter) are presented together with an interpretation of their significance in relation to the large scale combustion of these coals as thermal fuels in industrialized countries such as China and Canada. The detailed results showed wide variations in trace impurity concentrations (up to a factor of 100 and more) among the coals studied with few large differences between those of Chinese and Canadian origin except that the rare earths, Sc, Th, U, I, and Se were much higher in the former, other halogens, As and Na were lower. Values for elemental enrichment factors (EF) relative to normal crustal abundances indicated that only As(EF=13), Br(5.7), I(16), S(230), Sb(11) and Se(320) were appreciably enriched in coal. During static ashing at 750°C most of the halogens, S and Se were volatilized whereas most other inorganic constituents were highly retained and concentrated in the ash by factors of 6 to 11.