巯基乙酸稳定的CdSe/ZnS核壳结构量子点的制备与表征

用非均相成核原理,在水溶液中制备CdSe/ZnS核壳结构量子点,并研究合成工艺,包括前驱物的滴加方式和用量、CdSe核的水浴反应时间、CdSe与ZnS的摩尔比等因素对CdSe/ZnS核壳结构量子点荧光性能的影响.用透射电子显微镜和x射线衍射仪测试核壳结构量子点的形貌和结构.用紫外吸收光谱与荧光光谱表征CdSe/ZnS核壳结构量子点的荧光性能.结果表明:ZnS壳层在CdSe核量子点表面外延生长,形成了核壳结构;CdSe/ZnS核壳结构量子点的荧光性能明显高于单一的CdSe量子点;合成的工艺条件会显著影响CdSe/ZnS核壳结构量子点的荧光性能.     

CdSe量子点掺杂硼硅酸盐玻璃的光学性能

将CdO和ZnSe作为量子点引入前驱体,采用高温熔融冷却–热处理法,制备了CdSe量子点掺杂硼硅酸盐玻璃。透射电子显微镜测试表明,CdSe量子点呈六方晶结构。荧光光谱测试表明,CdSe量子点在可见波段存在本征发光和缺陷发光。随热处理温度增高,可以降低缺陷发光,提高量子点本征发光。研究了玻璃网络结构对CdSe量子点析晶影响。结果表明,随着B2O_3含量增大,玻璃中二维(2D)网络结构增多,Cd~(2+)和Se2–移动能力增强,有利于量子点析出和表面缺陷钝化。CdSe量子点波长可调谐发光的特性,使得其有望作为在可见光波段的光增益介质。     

CdSe/CdS-PVP纳米复合材料的制备及其光学性能研究

量子点由于高表面能而易于团聚,影响其使用价值。通常需要对量子点进行表面修饰,以提高材料的光电稳定性。首先通过化学键合法在水溶性CdSe/CdS量子点表面引入4,4-偶氮双(4-氰基戊酸)(ACVA),制备一种新型量子点引发剂CdSe/CdS-azo,然后引发单体N-乙烯基吡咯烷酮(NVP)聚合,成功制备出一种新型水溶性纳米复合材料CdSe/CdS-PVP。光学测试结果表明CdSe/CdS-PVP在多种溶剂中具有稳定而优异的发光性能。因此,该水溶性纳米复合材料CdSe/CdS-PVP有望作为生物荧光探针和示踪材料。     

CdTe量子点/PDDA多层膜的制备及对甲醛的检测

成功制备了L-半胱氨酸-CdTe/PDDA聚电解质多层膜(QDMF)气体传感器,并以此进行了有害气体甲醛的检测。以Te粉,NaBH4和CdCl2为原料制备前驱体,与修饰剂L-半胱氨酸混合,在氮气氛围下加热回流不同的时间得到所需量子点。通过带负点的量子点与带正电的PDDA之间的静电吸引进行层层自组装(LBL)得到聚电解质多层膜。并通过荧光光谱分析仪,紫外分光光度计等对量子点及多层膜进行表征,进一步证实本论文中制备的气体传感器性能稳定,并能灵敏的检测甲醛气体。     

硅壳包裹核/壳型CdSe/CdS纳米晶的制备与性能研究

采用低温水热技术,分别以柠檬酸、聚乙二醇(PEG400)和甲硫氨酸为稳定剂,在水相中合成了核壳型CdSe/CdS量子点,研究了稳定剂、CdSe与CdS物质的量比对量子点发光性能和结构的影响。XRD结果表明,当CdSe∶CdS在1∶3~4时,CdS主要在CdSe的外延生长,形成核壳型纳米粒子,当比例达到1∶5时,CdS单独成晶现象严重。CdSe∶CdS=1∶4时,核壳型量子点具有较高的荧光发射效率。TEM研究表明CdS在CdSe外表面生长形成较为完整的壳层,有效钝化CdSe表面,减少表面缺陷,从而显著提高CdSe量子点的发光效率。CdSe核尺寸为2~3nm的核壳型纳米粒子外包裹一层SiO2壳后,荧光发射效率没有显著提高,发射峰位置无明显红移。量子点包壳后能有效提高该量子点的光化学稳定性,提高量子点的生物相容性。     

CdSe:Mn量子点的制备及其光致发光特性研究

采用低温水热法,以柠檬酸为配位稳定剂制备了Mn2 掺杂的CdSe量子点.用紫外吸收光谱、荧光发射光谱、X射线衍射(XRD)、透射电镜(TEM)等进行了表征.研究了Mn2 掺杂浓度对量子点的结构及其光致发光性能的影响.光致发光光谱表明,当粒子尺寸为3 nm时,在580 nm处出现了属于Mn2 的4T1-6A1跃迁的特征发射峰.当激发波长为480nm时,在630nm处出现了CdSe的表面缺陷发射峰.随着Mn2 的掺杂浓度增大,CdSe:Mn表面陷阱态发射峰位置没有显著红移.TEM分析结果显示,CdSe:Mn量子点为单分散的,尺寸约为5 nm的圆形纳米粒子.当Mn2 离子掺杂浓度不大于5%时,Mn2 取代表面晶格中的Cd2 离子位置形成辐射性表面缺陷,产生表面陷阱态发射.吸收光谱显示,随着量子点变小,吸收带边发生蓝移,显示明显的量子尺寸效应.     

纳米碲化镉/石墨烯水溶液的制备及荧光性能研究

以石墨为原料,通过热还原法制备了还原性氧化石墨烯(rGO),然后采用水热法将CdTe量子点与r GO以非共价键的方式复合在一起,制备出了纳米CdTe/rGO水溶液。通过X射线衍射仪、紫外-可见分光光度计、透射电子显微镜和荧光分光光度计对样品进行了表征。结果表明,160℃下水热30 min制备的CdTe/rGO荧光性能最好。CdTe量子点均匀地负载在rGO表面;CdTe量子点的团聚体尺寸由复合前的220 nm减小到60~120 nm;并在527 nm处产生荧光猝灭,说明rGO与CdTe量子点之间存在着光诱导电子转移,从而为制备性能可靠的光伏器件提供可能。     

CdSe∶Mn量子点的制备及其光致发光特性研究

采用低温水热法,以柠檬酸为配位稳定剂制备了Mn2＋掺杂的CdSe量子点。用紫外吸收光谱、荧光发射光谱、X射线衍射（XRD）、透射电镜（TEM）等进行了表征。研究了Mn2＋掺杂浓度对量子点的结构及其光致发光性能的影响。光致发光光谱表明,当粒子尺寸为3 nm时,在580 nm处出现了属于Mn2＋的4T1-6A1跃迁的特征发射峰。当激发波长为480 nm时,在630 nm处出现了CdSe的表面缺陷发射峰。随着Mn2＋的掺杂浓度增大,CdSe∶Mn表面陷阱态发射峰位置没有显著红移。TEM分析结果显示,CdSe∶Mn量子点为单分散的,尺寸约为5 nm的圆形纳米粒子。当Mn2＋离子掺杂浓度不大于5%时,Mn2＋取代表面晶格中的Cd2＋离子位置形成辐射性表面缺陷,产生表面陷阱态发射。吸收光谱显示,随着量子点变小,吸收带边发生蓝移,显示明显的量子尺寸效应。     

纳米碲化镉/石墨烯水溶液的制备及荧光性能研究

以石墨为原料,通过热还原法制备了还原性氧化石墨烯(rGO),然后采用水热法将CdTe量子点与rGO以非共价键的方式复合在一起,制备出了纳米CdTe/rGO水溶液。通过X射线衍射仪、紫外-可见分光光度计、透射电子显微镜和荧光分光光度计对样品进行了表征。结果发现,160℃下水热30min制备的CdTe/rGO荧光性能最好。CdTe量子点均匀地负载在rGO表面;CdTe量子点的团聚体尺寸由复合前的220nm减小到60nm~120nm;并在527nm处产生荧光猝灭,说明rGO与CdTe量子点之间存在着光诱导电子转移,从而为制备性能可靠的光伏器件提供可能。     

量子点-聚苯乙烯复合微球的制备及荧光光谱的研究

用无皂乳液聚合制备了交联聚苯乙烯微球,讨论了单体、引发剂浓度,共聚单体等对微球粒径,单分散性的影响,并用FTIR和SEM对上述样品的结构进行了表征。在单体的配方中,加入1%二乙烯基苯作为交联剂,加入1%丙烯酸使小球表面功能化,便于后续与无机量子点和有机材料的结合。以氯仿/正丁醇为混合溶胀剂,将聚合物微球与CdSe量子点或CdSe/ZnS复合,制得含有两种或两种以上的不同量子点的高分子复合荧光微球。通过荧光光谱的测试,出现了两个或两种以上互不干扰的特征峰。为在聚合物微球中注入多种量子点,制得荧光探针,并实施量子点编码进行了初步的前期探索工作。     

Insect antifeedant properties of anthranoids from the genusVismia

Vismiones and ferruginins, representatives of a new class of lypophilic anthranoids from the genusVismia were found to inhibit feeding in larvae of species ofSpodoptera, Heliothis, and inLocusta migratoria.     

Direct observation of freeze-thaw instability of latex coatings via high pressure freezing and cryogenic SEM

Despite its industrial importance, the subject of freeze-thaw (F/T) stability of latex coatings has not been studied extensively. There is also a lack of fundamental understanding about the process and the mechanisms through which a coating becomes destabilized. High pressure (2100 bar) freezing fixes the state of water-suspended particles of polymer binder and inorganic pigments without the growth of ice crystals during freezing that produce artifacts in direct imaging scanning electron microscopy (SEM) of fracture surfaces of frozen coatings. We show that by incorporating copolymerizable functional monomers, it is possible to achieve F/T stability in polymer latexes and in low-VOC paints, as judged by the microstructures revealed by the cryogenic SEM technique. Particle coalescence as well as pigment segregation in F/T unstable systems are visualized. In order to achieve F/T stability in paints, latex particles must not flocculate and should provide protection to inorganic pigment and extender particles. Because of the unique capabilities of the cryogenic SEM, we are able to separate the effects of freezing and thawing, and study the influence of the rate of freezing and thawing on F/T stability. Destabilization can be caused by either freezing or thawing. A slow freezing process is more detrimental to F/T stability than a fast freezing process; the latter actually preserves suspension stability during freezing. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004 in Chicago, IL. Tied for first place in The John A. Gordon Best Paper Competition.     

Ethanol and (−)-α-Pinene: Attractant Kairomones for Bark and Ambrosia Beetles in the Southeastern US

In 2002–2004, we examined the flight responses of 49 species of native and exotic bark and ambrosia beetles (Coleoptera: Scolytidae and Platypodidae) to traps baited with ethanol and/or (−)-α-pinene in the southeastern US. Eight field trials were conducted in mature pine stands in Alabama, Florida, Georgia, North Carolina, and South Carolina. Funnel traps baited with ethanol lures (release rate, about 0.6 g/day at 25–28°C) were attractive to ten species of ambrosia beetles (Ambrosiodmus tachygraphus, Anisandrus sayi, Dryoxylon onoharaensum, Monarthrum mali, Xyleborinus saxesenii, Xyleborus affinis, Xyleborus ferrugineus, Xylosandrus compactus, Xylosandrus crassiusculus, and Xylosandrus germanus) and two species of bark beetles (Cryptocarenus heveae and Hypothenemus sp.). Traps baited with (−)-α-pinene lures (release rate, 2–6 g/day at 25–28°C) were attractive to five bark beetle species (Dendroctonus terebrans, Hylastes porculus, Hylastes salebrosus, Hylastes tenuis, and Ips grandicollis) and one platypodid ambrosia beetle species (Myoplatypus flavicornis). Ethanol enhanced responses of some species (Xyleborus pubescens, H. porculus, H. salebrosus, H. tenuis, and Pityophthorus cariniceps) to traps baited with (−)-α-pinene in some locations. (−)-α-Pinene interrupted the response of some ambrosia beetle species to traps baited with ethanol, but only the response of D. onoharaensum was interrupted consistently at most locations. Of 23 species of ambrosia beetles captured in our field trials, nine were exotic and accounted for 70–97% of total catches of ambrosia beetles. Our results provide support for the continued use of separate traps baited with ethanol alone and ethanol with (−)-α-pinene to detect and monitor common bark and ambrosia beetles from the southeastern region of the US.     

Methyl 2,4,6-decatrienoates Attract Stink Bugs and Tachinid Parasitoids

Halyomorpha halys (Stål) (Pentatomidae), called the brown marmorated stink bug (BMSB), is a newly invasive species in the eastern USA that is rapidly spreading from the original point of establishment in Allentown, PA. In its native range, the BMSB is reportedly attracted to methyl (E,E,Z)-2,4,6-decatrienoate, the male-produced pheromone of another pentatomid common in eastern Asia, Plautia stali Scott. In North America, Thyanta spp. are the only pentatomids known to produce methyl 2,4,6-decatrienoate [the (E,Z,Z)-isomer] as part of their pheromones. Methyl 2,4,6-decatrienoates were field-tested in Maryland to monitor the spread of the BMSB and to explore the possibility that Thyanta spp. are an alternate host for parasitic tachinid flies that use stink bug pheromones as host-finding kairomones. Here we report the first captures of adult and nymph BMSBs in traps baited with methyl (E,E,Z)-2,4,6-decatrienoate in central Maryland and present data verifying that the tachinid, Euclytia flava (Townsend), exploits methyl (E,Z,Z)-2,4,6-decatrienoate as a kairomone. We also report the unexpected finding that various isomers of methyl 2,4,6-decatrienoate attract Acrosternum hilare (Say), although this bug apparently does not produce methyl decatrienoates. Other stink bugs and tachinids native to North America were also attracted to methyl 2,4,6-decatrienoates. These data indicate there are Heteroptera in North America in addition to Thyanta spp. that probably use methyl 2,4,6-decatrienoates as pheromones. The evidence that some pentatomids exploit the pheromones of other true bugs as kairomones to find food or to congregate as a passive defense against tachinid parasitism is discussed.     

2007～2008年世界塑料工业进展

收集了2007年7月～2008年6月世界塑料工业的相关资料,介绍了2007～2008年国外塑料工业的发展情况,提供了世界塑料产量、消费量及全球各类树脂的需求量及产能情况.按通用热塑性树脂(聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂)、工程塑料(尼龙、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚)、特种工程塑料(聚苯·硫醚、液晶聚合物、聚醚醚酮)、通用热固性树脂(酚醛、聚氨酯、不饱和聚酯树脂、环氧树脂)不同品种的顺序,对树脂的产量、消费量、供需状况及合成工艺、产品应用开发、树脂品种的延伸及应用的进一步扩展等技术作了详细介绍.     

2005～2006年国外塑料工业进展

收集了2005年7月～2006年6月国外塑料工业的相关资料,介绍了2005—2006年国外塑料工业的发展情况。提供了世界塑料产量、消费量及全球各类树脂生产量以及各国塑料制品的进出口情况。作为对比,介绍了中国塑料的生产情况。按通用热塑性树脂（聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂）、工程塑料（聚酰胺、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚）、通用热固性树脂（酚醛、聚氨酯、不饱和树脂、环氧树脂）、特种工程塑料（聚苯硫醚、液晶聚合物、聚醚醚酮）的品种顺序,对树脂的产量、消费量、供需状况及合成工艺、产品开发、树脂品种的延伸及应用的扩展作了详细的介绍。