中远红外超宽波段高反射一维光子晶体薄膜结构设计

红外高反射薄膜是实现超低损耗光学器件、红外隐身等技术的关键基础材料.根据多层光学薄膜的传输矩阵原理,得到一维光子晶体的反射率和透射率表达式,分析推导了一维光子晶体的能带结构.利用传输矩阵原理,以Ge和SiO2为介质材料设计了28层λ/4一维光子晶体结构.随后,利用有限元法计算其光子能带,使用折射率差值更大的PbSe和S...     

三层平板光波导横模解析理论

光波导可以被广泛应用在集成光学各个领域。在实验条件具备的情况下,设计和制作各种实用的集成光学器件,探索制作新工艺,当然对集成光学的发展具有推动作用,然而,在实验条件不具备的情况下,从理论上对各种波导的模式理论进行分析,并在此基础上提出更有效和更简便的理论分析方法,无疑对各种集成光学器件的设计和计算也具有重要的实际意义。     

光纤的模式理论

光波导可以被广泛应用在集成光学各个领域。在实验条件具备的情况下,设计和制作各种实用的集成光学器件,探索制作新工艺,当然对集成光学的发展具有推动作用,然而,在实验条件不具备的情况下,从理论上对各种波导的模式理论进行分析,并在此基础上提出更有效和更简便的理论分析方法,无疑对各种集成光学器件的设计和计算也具有重要的实际意义。     

光波导数值计算方法

光波导可以被广泛应用在集成光学各个领域。在实验条件具备的情况下,设计和制作各种实用的集成光学器件,探索制作新工艺,当然对集成光学的发展具有推动作用,然而,在实验条件不具备的情况下,从理论上对各种波导的模式理论进行分析,并在此基础上提出更有效和更简便的理论分析方法,无疑对各种集成光学器件的设计和计算也具有重要的实际意义。     

含氟聚酰亚胺有机聚合物波导的制备

采用含氟单体4,4′-（六氟异丙基）-苯二酸酐（6FDA）、5,5′-（六氟异丙基）-二-（2-氨基苯酚）（6FHP）及二氨基二苯醚（ODA）合成了含氟聚酰亚胺共聚物材料,对材料的化学和光学性能进行了表征,共聚物材料在溶液状态下用旋涂法获得了较高质量的共聚物薄膜,并在此基础上采用先进的光波导工艺技术将该材料制备成条波导,测试结果表明该波导在光通信波段1550nm处的平均传输损耗小于0．66dB／cm,局部损耗在0．2dB／cm,进一步改进后有望获得性能优异的光电子器件．     

MOPc／DEH双组分单层结构有机光导器件的制作及其光电特性

制作了由金属酞菁，腙和高分子成膜剂组成的单层有机光导器件，测试了单层光导器件的光电性能参数，实验结果表明，这种单层光导器件对白光最敏感，可进行正负性充放电，有优异的光电性能，本文还探讨了MOPc/DEH双组分单层光导器件的电荷传输机理。     

红外光导纤维材料:ZrF_4-BaF_2-LaF_3系玻璃的研究

激光通信用纤维低损耗的研究是七十年代展开的.在这十年中,从理论和实践上弄清了石英玻璃纤维中光波的损耗原因;得到了与理论固有损耗值0.18dB/km基本上一致的实验值0.2dB/km(1.55μm).在非石英系光导纤维材料中,目前提出的有重金属氧化物玻璃、硫化物玻璃、卤化物晶体、氟化物玻璃和液芯纤维等.对这些材料感兴趣的主要原因是:用这些材料制成的可挠性纤维可传输CO_2激光能量和传输石英光纤不能传输的2μm以上的红外线.目前正在调查实现传输损耗为10~(-3)dB/km(约为石英纤维的1/100)的超低损     

波导电铸

波导是无线电通讯设备中的关键元件之一.随着国防工业和航空工业的不断发展,电子设备也相应地向高精尖方面迈进,其微波器件的应用也越来越广.为了满足多方面的技术要求,波导元件的形状和结构也愈加复杂,加工的精度和光洁度也愈加提高.如园方过渡波导、梯形波导、软波导和多向长方喇叭波导等,都在电子设备中获得实际应用.波导电铸比机加工有更多优点.它不仅能成型机械法难以加工的复杂波导,而且能满足     

波导管隔板对废旧橡胶裂解传输功率的影响

采用HFSS软件模拟分析2 450 MHz频率下在波导管中设置石英板对废旧橡胶微波裂解传输功率的影响。结果表明,设置双层石英板且保持合适间距有利于提高波导管能量传输效率,极大地减小能量损耗,解决了废旧橡胶微波裂解中出现的能耗过大及波源易损坏的难题,提高了微波裂解效率以及裂解设备的可靠性和安全性。     

高分子弹性体的表面形貌及其摩擦性能

与其他材料相比,高分子弹性体材料的质地更轻、耐高温效果显著,当前被应用在建筑工程建设、医疗与电子信息传输等行业中。由于较大摩擦力会导致设备使用寿命缩短,因此在高分子摩擦材料基础上,也需以提高高分子弹性润滑度、控制摩擦损耗为目标。针对此,以高分子弹性体表面形貌为切入点,提出高分子弹性体摩擦性能特征,以供参考。     

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.     

Novel polyurethane coating technology through glycidyl carbamate chemistry

Glycidyl carbamate chemistry combines the excellent properties of polyurethanes with the crosslinking chemistry of epoxy resins. Glycidyl carbamate functional oligomers were synthesized by the reaction of polyfunctional isocyanate oligomers and glycidol. The oligomers were formulated into coatings with several amine functional crosslinkers at varying stoichiometric ratios and cured at different temperatures. Properties such as solvent resistance, hardness, and impact resistance were dependent on the composition and cure conditions. Most coatings had an excellent combination of properties. Studies were carried out to determine the kinetics of the curing reaction of the glycidyl carbamate functional oligomers with multifunctional and model amines. Detailed kinetic analysis of the curing reactions was also undertaken. The results indicated that the glycidyl carbamate functional group is more reactive than a glycidyl ether group. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, on October 27–29, 2004, in Chicago, IL.     

Highly moisture-proof polysilsesquioxane coating prepared via facile sol-gel process

A highly moisture-proof polysilsesquioxane coating was obtained from a new bis-silylated precursor, which was synthesized from 3-aminopropyltriethoxysilane (APTES) and m-xylylene diisocyanate (m-XDI) in tetrahydrofuran (THF) and verified by ¹H MAS NMR. For direct comparison purposes, an SiO₂ coating was also prepared by the Stöber method using tetraethoxysilane (TEOS) as the reactant. Interestingly, the coating obtained from the polysilsesquioxane sol exhibited a much higher moisture resistance capability than its counterpart, which was attributed to its more compact feature between nanoparticles as characterized by N₂ absorption experiment and transmission electron microscopy (TEM). Furthermore, its high transparency of about 92% showed potential for application in the protection of optical crystals.     

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.