Bi和Nd共掺CsI晶体近红外宽带发光性能

采用坩埚下降法生长了Bi和Nd共掺的CsI晶体.X射线衍射分析表明,Bi和Nd共掺并不影响晶体结构,其空间群为Pm3m.通过测试晶体的实际掺杂浓度发现,共掺导致了Bi掺杂浓度的降低.对晶体进行退火处理,并测试了晶体的吸收光谱和发射光谱.结果表明:Bi和Nd共掺能够提高晶体中带电子色心V'Cs的浓度,经高温退火后能获得较多的低价态的Bi离子发光团簇,从而提高了晶体的近红外宽带发光性能.晶体的Raman 光谱显示,掺Bi的CsI晶体近红外宽带发光中心的2个特征Raman峰分别位于164和176 cm-1处.此外,还提出CsI晶体中发光中心Bi+和低价态团簇Bi2+的形成离不开高价态Bi离子的靠拢团聚作用.     

掺质钆镓石榴石晶体的生长及色泽的研究

生长了分别掺Cr、Nd、Co和Ni的钆镓石榴石晶体,不同掺质的晶体具有不同的色泽。用化学分析方法估算了Cr、Co和Ni在此晶体中的有效分凝系数,其数值分别为2.7、0.19和0.017。在 0.3～0.7μm的光波范围内测了这些掺质晶体的光学透过性质。γ射线辐照实验表明,辐照后晶体的色泽有不同程度的变化。     

掺钕钨酸钇钠晶体的缺陷

掺钕钨酸钇钠晶体Nd:NaY(WO4)2是一种性能优良的激光晶体.对该晶体中的包裹物、生长台阶等缺陷进行了观察,并分析了缺陷产生的原因.在晶体的不同部位取样进行扫描电镜和能谱分析,发现随着晶体生长过程的进行,晶体中Nd3 的浓度逐渐增加.研究了晶体中位错蚀坑的分布特点,发现位错蚀坑的密度与晶体生长的不同部位、Nd3 的掺杂浓度等因素有关.     

Nd:YAG晶体的光谱测试及其新波长激光

采用提拉法生长了掺Nd3+量为1.2%(摩尔分数)的Nd3+:Y3A15O12(Nd:YAG)激光晶体.测定了Nd:YAG晶体室温下300～3 000nm的吸收光谱和808nm激光激发的荧光光谱,核定了Stark能级的位置.结果表明:Nd:YAG晶体产生的1.3μm波长激光适用于光通讯,并具有人眼安全,对大气吸收低等特点,可用于激光雷达和和外科手术.4F3/2→4I9/2跃迁的946 nm激光,倍频后产生的473nm蓝色激光,在激光存储和光显示方面有重要应用.4F3/2→4I11/2跃迁的1122nm激光倍频后可产生561 nm黄色激光,可用作生物显微镜光源.     

掺Nd系LiNbO3晶体的生长及外泵浦位相共轭激光器的特性

用提拉法生长Nd:LiNbO3(Nd:LN),In:Nd:LN和Ce:Nd:LN晶体.测试晶体的紫外-可见吸收光谱和抗光损伤能力.结果表明:Nd:LN晶体的吸收边相对同成分纯LN晶体向长波方向移动;In:Nd:LN晶体的吸收边相对Nd:LN晶体向短波方向移动;Ce:Nd:LN晶体的吸收边向长波方向移动.In:Nd:LN晶体的抗光损伤能力比Nd:LN晶体的提高1个数量级以上.以掺Nd系LN光折变晶体为位相共轭镜,He-Ne气体为激活介质,构成外泵浦位相共轭激光器.实验表明:掺Nd系LN晶体外泵浦位相共轭激光器的输出特性稳定,In:Nd:LN晶体的输出光强比Fe:LN晶体的提高了近1个数量级.     

Nd:NaBi(WO4)2晶体生长

采用Czochralski法生长出尺寸为φ8mm×20 mm的掺钕的钨酸铋钠[分子式:Nd:NaBi(WO4)2,简称:Nd:NBW]激光晶体,研究了生长工艺参数对Nd∶NBW晶体结构完整性的影响,确定了最佳的生长工艺参数:轴向温度梯度为0.7～1 ℃/mm,生长速率0.2～0.5 mm/h,晶体转速1～4 r/min.并利用了X射线衍射确定了Nd∶NBW晶体属于四方晶系,I41/a空间群,其晶格常数为a=0.527 5 nm, c=1.149 3 nm.通过TG-DTA分析了Nd∶NBW晶体的相关物理、化学性质,确定了其熔点为936.2 ℃,并与纯的钨酸铋钠晶体(分子式:NaBi(WO4)2,简称:NBW)进行了对比性研究.     

钕单掺LiNbO_3晶体缺陷结构分析

采用提拉法生长了掺Nd~(3+)浓度为0.2 mol(N1)%,0.5 mol(N2)%,0.8 mol(N3)%的Nd:LiNbO_3晶体。测试了Nd:LiNbO_3晶体的红外吸收光谱、紫外-可见吸收光谱并深入研究了其内部缺陷结构。通过对光谱的测试与分析得出:Nd~(3+)在低浓度掺杂过程中优先取代反位铌NbLi~(4+)位及Li~+位,随着掺杂浓度的增加主要取代反位铌NbLi~(4+)位。     

K4体系KTP晶体的制备及其性能研究

本文选用K4P2O7助溶剂体系生长KTP晶体,所生长的晶体具有低吸收率和蓝、绿光波段抗灰迹性能,确定其最佳生长配比为KTP/K4 =0.8 mol/mol,测定其饱和点为850℃左右,从饱和点缓慢降温到820℃所生长晶体质量最佳,并对其进行了PCI抗灰迹吸收测试、倍频效率测试、电导率测试.结果表明:在同样原料纯度的情况下,吸收系数只有普通K6体系KTP晶体的十几分之一;1064 nm调Q到绿光的转化效率为61.8％(普通KTP转化效率为50％);在1 kV直流长时间加压条件下,Z向电导率达到10-10S/cm量级,较普通K6体系生长的KTP晶体低2～3个数量级.     

Nd∶NaBi(WO_4)_2晶体生长

采用Czochralski法生长出尺寸为 8mm× 2 0mm的掺钕的钨酸铋钠 [分子式 :Nd∶NaBi(WO4) 2 ,简称 :Nd∶NBW ]激光晶体 ,研究了生长工艺参数对Nd∶NBW晶体结构完整性的影响 ,确定了最佳的生长工艺参数 :轴向温度梯度为 0 .7～ 1℃ /mm ,生长速率 0 .2～ 0 .5mm/h ,晶体转速 1～ 4r/min。并利用了X射线衍射确定了Nd∶NBW晶体属于四方晶系 ,I41 /a空间群 ,其晶格常数为a =0 .5 2 75nm ,c=1.14 93nm。通过TG -DTA分析了Nd∶NBW晶体的相关物理、化学性质 ,确定了其熔点为 936.2℃ ,并与纯的钨酸铋钠晶体 (分子式 :NaBi(WO4) 2 ,简称 :NBW)进行了对比性研究     

抗灰迹Rb∶KTP晶体的生长及性能研究

本文采用K6P4O13(K6)作助熔剂来生长Rb∶KTP晶体,所生长的晶体具有电导率低,吸收系数稳定和好的抗灰迹性能等优点.本文按照生长比例KTP∶K6=1.345∶1(物质的量比),Rb离子浓度为取代溶液中K离子浓度的1.4 mol％左右来进行配料.测量了Rb∶KTP晶体中掺杂的Rb离子浓度为0.87 mol％,经过测试,晶体的电导率达到10-10 S/cm.测试了晶体随时间延长的光能吸收,发现Rb∶KTP晶体的吸收系数比较稳定,并进行了晶体抗灰迹性能激光测试,发现Rb∶KTP晶体较普通KTP晶体具有很好的抗灰迹性能.     

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。