液相自组装Ce、W掺杂VO2薄膜的制备及其性能研究

利用三氯十八烷基硅烷(octadecyltrichlorosilane--OTS)为模板,以草酸、五氧化二钒,硝酸铈、钨酸铵、为原料,利用自组装薄膜技术,在玻璃基片上成功制备了氧化钒薄膜。测量了紫外光照射后OTS薄膜的亲水性。通过X射线衍射研究了自组装氧化钒薄膜的晶体结构,利用扫描电镜观察了薄膜的表面形貌,表明通过自组装制备的氧化钒薄膜通过退火处理后,可以良好的在玻璃基片上成膜,薄膜质量良好。通过FTIR测试表明,1%Ce和1.5%W共掺杂的VO2薄膜其相变温度从65℃降低到28℃。     

热处理对BiO_x薄膜的组成和结构的影响

采用反应磁控溅射法在氧气和氩气比例为20∶100的混合气体中制备了非化学计量的氧化铋薄膜。薄膜分别在真空和空气中400℃退火30min。采用X射线光电子能谱(XPS)和X射线衍射(XRD)研究了薄膜在真空和空气中退火对其组成和结构的影响。分析表明,在真空退火条件下薄膜中的金属铋和次氧化铋发生了相变,金属铋晶粒长大;而在空气中退火时薄膜主要发生了金属铋和次氧化铋的氧化过程,得到了四方Bi2O3。     

真空蒸发法制备氧化钒薄膜的研究

以V2O5粉末为原料,采用真空蒸发结合真空热处理方法制备V O x薄膜,运用X R D(X射线衍射)和SE M(扫描电子显微镜)技术分析了基片材料、基片温度、真空热处理工艺对氧化钒薄膜结晶状态、物相组成和表面形貌的影响,在基片温度为200℃和400℃时所沉积的氧化钒薄膜在室温附近的电阻温度系数(TC R)分别达到-3%,并发现随着基片温度的升高,薄膜在室温附近的电阻率降低,TC R绝对值减小。     

脉冲准分子激光扫描沉积(PLD)高c轴取向V_2O_5/Si薄膜及结构分析

采用脉冲准分子激光大面积扫描沉积技术 ,在Si(111)单晶衬底上沉积了多晶V2 O5 薄膜 ,经 3 0 0℃以上退火处理得到了具有高c -轴取向生长的V2 O5 薄膜 .3 0 0℃以上热退火处理的薄膜表面具有正常的化学计量比 (无氧缺位 ) ,晶粒间界明显 ,晶粒呈针棒状 ,晶粒尺寸在10 0～ 2 0 0nm之间 .采用X射线衍射 (XRD)、Raman光谱 (RS)、Fourier红外光谱 (FT -IR)及透射电镜扫描附件 (STEM )对沉积及不同温度下退火处理的样品进行了结构分析 .研究结果表明 :V2 O5 /Si薄膜经 40 0℃热处理后表面部分处于低价态的钒离子已被氧化为V2 O5 .     

脉冲准分子激光扫描沉积(PLD)高c轴取向V2O5/Si薄膜及结构分析

采用脉冲准分子激光大面积扫描沉积技术,在Si(111)单晶衬底上沉积了多晶V2O5薄膜,经300℃以上退火处理得到了具有高c-轴取向生长的V2O5膜。300℃以上热退火处理的薄膜表面具有正常的化学计量比（无氧缺位）,晶粒间界明显,晶粒呈针棒状,晶粒尺寸在100－200nm之间。采用X射线衍射（XRD）、Raman光谱（RS）、Fourier红外光谱（FT－IR）及透射电镜扫描附件（STEM）对沉积及不同温度下退火处理的样品进行了结构分析。研究结果表明：V2O5/Si薄膜经400℃热处理后表面部分处于低价态的钒离子已被氧化为V2O5。     

钨掺杂M型二氧化钒粉体的水解法制备与结构分析

采用水解法制备不同W掺杂量的VO2(M)粉体。借助于X射线衍射仪、Fourier变换红外谱、差示扫描量热仪、X射线光电子谱仪和X射线精细结构谱对粉体的成分和结构进行表征。结果表明,W6+进入VO2晶格,形成固溶体V4+1-3xV3+2xWxO2。W掺杂降低了VO2(M)的相变温度,相变温度与W掺杂量在一定范围内成线性关系,掺杂效率约为18℃/1%(摩尔分数)。掺杂的大半径W原子部分替换了VO2(M)晶格中的V原子,晶格膨胀畸变产生的压应力通过共享顶点O,沿着W—O—V链传递到邻近的次晶格,造成V—O键键长变化,促使V周围的氧分布对称性随W掺杂量的增加而增大。当W掺杂量增大至2.5%时,单斜结构中的V—O1键和V—V1a键伸长,V—O2键和V—V1b键缩短,V—O1和V—O2峰合并成金红石结构的V—O峰,V—V1a峰和V—V1b峰合并成金红石结构的V—V1峰,即样品已转变为金红石结构。     

热处理V膜制备VO_(2)薄膜的结构和光电性能EI北大核心CSCD

先用磁控溅射法在石英玻璃基片上制备了金属V膜,然后经过真空退火处理被转变为VO_(2)薄膜。研究了退火温度对VO_(2)薄膜表面形貌、晶体结构、光学性能和电学性能的影响。结果表明:随着退火温度由300℃增加到450℃,VO_(2)薄膜的结晶度明显增加。退火温度在400℃和450℃制备的样品是高纯M相单斜结构,晶粒发育较好,晶界清晰。不同温度退火的样品的表面V元素包含由4+和5+态,5+态的出现是由于表面V元素受环境中氧化导致。虽然退火温度的改变对VO_(2)薄膜的可见光透过率无明显影响,但是可以改善对太阳光的调节效率。VO_(2)薄膜半导体-金属相变温度和半导体相的电阻随热处理温度增加而增加,在400℃和450℃退火样品电阻相变前后的变化幅度可达2个数量级,450℃退火制备样品的滞后宽度和半导体金属相变临界温度分别为14.6℃和61.0℃。     

VO_2-WO_3复合薄膜的制备及其热致变色-电致变色性能研究

智能玻璃是目前建筑节能重点研究方向。本研究将自制氧化钒纳米粉体均匀分散到钨溶胶体系,取上清液旋涂于ITO基板,经干燥、退火后制得VO_2(M)-非晶WO_3复合薄膜。实验结果表明,所制备的VO_2(M)-非晶WO_3复合薄膜兼具热致变色和电致变色性能,通电后薄膜表现典型的电致变色特征,可见光和近红外光透过率明显下降。退火过程中,部分W掺杂到VO_2中,使薄膜的热致相变温度降低10°C左右。复合薄膜在双响应条件下,其可见光透过率为32.6%、调控效率为18.8%。     

Li~+离子嵌入V_2O_5干凝胶薄膜的XPS研究

V2 O5薄膜是最具有实用价值的全固态“灵巧窗”器件中候选锂离子储存材料之一。本研究采用熔融淬冷法成功制备了V2 O5溶胶 ,利用提拉法在ITO玻璃片上制备了表面均匀和无裂纹的V2 O5干凝胶薄膜 ,并采用电化学方法将Li+ 离子嵌入到V2 O5干凝胶薄膜中。本文着重采用X射线光电子能谱 (XPS)分析了Li+ 离子嵌入V2 O5干凝胶薄膜前后的化学组成及钒、氧、锂离子的化学状态     

热致变色V02薄膜的制备及研究进展

VO2作为一种最有应用潜力的功能材料,在智能窗等许多领域发挥着非常重要的作用.V02是一种热致变色材料,相变温度为68℃,相变前后VO2光学性能有较大的变化.详细介绍YVO2薄膜的各种制备方法;同时,分析了降低VO2薄膜相变温度及提高VO2薄膜可见光透过率的方法,并综述了其应用领域.     

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.     

Many Drugs of Abuse May Be Acutely Transformed to Dopamine,Norepinephrine and Epinephrine In Vivo

It is well established that a wide range of drugs of abuse acutely boost the signaling of the sympathetic nervous system and the hypothalamic–pituitary–adrenal (HPA) axis, where norepinephrine and epinephrine are major output molecules. This stimulatory effect is accompanied by such symptoms as elevated heart rate and blood pressure, more rapid breathing, increased body temperature and sweating, and pupillary dilation, as well as the intoxicating or euphoric subjective properties of the drug. While many drugs of abuse are thought to achieve their intoxicating effects by modulating the monoaminergic neurotransmitter systems (i.e., serotonin, norepinephrine, dopamine) by binding to these receptors or otherwise affecting their synaptic signaling, this paper puts forth the hypothesis that many of these drugs are actually acutely converted to catecholamines (dopamine, norepinephrine, epinephrine) in vivo, in addition to transformation to their known metabolites. In this manner, a range of stimulants, opioids, and psychedelics (as well as alcohol) may partially achieve their intoxicating properties, as well as side effects, due to this putative transformation to catecholamines. If this hypothesis is correct, it would alter our understanding of the basic biosynthetic pathways for generating these important signaling molecules, while also modifying our view of the neural substrates underlying substance abuse and dependence, including psychological stress-induced relapse. Importantly, there is a direct way to test the overarching hypothesis: administer (either centrally or peripherally) stable isotope versions of these drugs to model organisms such as rodents (or even to humans) and then use liquid chromatography-mass spectrometry to determine if the labeled drug is converted to labeled catecholamines in brain, blood plasma, or urine samples.     

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.