大孔/介孔Ag/AgBr/TiO2复合光催化剂的制备及其可见光光催化活性

以钛酸四丁酯、硝酸银、溴化钠为前驱体,先采用无模板法制备大孔/介孔TiO_2,再通过浸渍沉淀法和光还原法制备大孔/介孔Ag/AgBr/TiO_2复合光催化剂,通过SEM、XRD、FTIR、BET、XPS、DRS对其进行了表征,并评价了可见光下Ag/AgBr/TiO_2降解罗丹明B水溶液的光催化活性。结果表明,Ag/AgBr改性对大孔/介孔TiO_2的形貌、比表面积、晶型结构、带隙结构和光催化活性影响显著。在Ag/AgBr与TiO_2物质的量比为1时,Ag/AgBr/TiO_2复合光催化剂的光催化活性最高,降解速率常数为50.21×10~(-3) min~(-1),分别是纯TiO_2和纯AgBr的14.5倍和2.15倍。     

回流法制备TiO2微球及其结构和催化性能研究

采用回流法制备了介孔TiO2微球催化剂,利用XRD、FE -SEM、BET等方法对所制备的催化剂进行了表征,并与溶剂热法制备的样品进行比较,研究不同制备方法对TiO2结构、彤貌及催化性能的影响.结果表明,回流法制备的样品为锐钛矿单相微球,晶粒间堆积形成介孔结构,比表面积大;而溶剂热法制备的介孔样品含金红石和锐钛矿两相.以EtOH/HCl为回流溶剂制备的样品孔径约为5nm,孔径分布窄,比表面积可达496 m2/g,光催化去除Cr(Ⅵ)反应速率快,去除率达到99％.     

酚醛树脂辅助合成SiO2/TiO2介孔复合微球及其光催化

利用Stber法合成的纳米SiO2为前体,在酚醛树脂和十六烷基三甲基溴化铵(CTAB)辅助下制备SiO2/TiO2介孔复合微球,并利用XRD、SEM、EDS、BET、BJH以及FTIR对材料的晶型、形貌以及结构进行了表征,以罗丹明B为目标降解物评价样品的光催化性能。结果表明,SiO2/TiO2介孔复合微球是由TiO2和SiO2组成,直径约300 nm,TiO2以纳米薄层方式均匀地沉积在SiO2表面,界面之间存在Si—O—Ti键;SiO2/TiO2介孔复合微球的比表面积为92.3 m2/g,较P25提高了约3倍。光催化评价表明,SiO2/TiO2介孔复合微球对罗丹明B的降解率达98%,较P25光催化降解率有明显提高。     

离子液体辅助Fe掺杂TiO2的制备及可见光活性

以钛酸四丁酯为钛源,FeC2O4·2H2O为铁源,离子液体([C4MIM] BF4)为模板剂采用溶胶凝胶法制备了具有大比表面积及可见光活性的Fe掺杂介孔TiO2光催化材料.采用X射线衍射仪、氮气吸附-脱附仪、透射电子显微镜、紫外可见吸收光谱对样品进行表征.结果表明所制备样品IL-Fe/TiO2中TiO2主要以锐钛矿相存在,Fe掺杂量对TiO2晶相影响不大,样品IL-0.1％ Fe/TiO2具有介孔结构和较大的比表面积,颗粒尺寸在30 nm左右.紫外可见光谱分析表明铁掺杂后TiO2的吸收带红移,带隙能降低.以亚甲基蓝为模拟污染物,在可见光(λ＞420 nm)下测定样品光催化活性,结果表明IL-0.1％ Fe/TiO2的可见光催化活性最高.     

AgBr/ZnO复合材料光催化剂及其光催化性能

通过一步水热法制备了AgBr/ZnO复合光催化剂,并采用扫描电子显微镜、透射电子显微镜、X射线衍射仪、X射线光电子能谱仪、紫外–可见光漫反射光谱仪和光致发光光谱仪对样品进行表征,分析了AgBr/ZnO体系的合成对材料光催化性能的影响。以罗丹明B溶液为目标污染物,研究复合催化剂的光催化活性。结果表明:在制备的复合样品中,Ag Br与ZnO摩尔比为1:5时(AgBr/ZnO-2)光催化活性最好,在可见光照射下,60 min对罗丹明B的降解率可达98.98%,相比于ZnO光催化活性明显提升,降解速率常数提升了11.08倍;与商用TiO2(P25)相比,降解速率常数提升了10.14倍,这主要归因于Ag Br/ZnO拥有比ZnO更低的电子空穴复合概率,且复合催化剂的光学吸收带边发生红移,从而增强了对可见光的吸收。     

回流法制备TiO_2微球及其结构和催化性能研究

采用回流法制备了介孔TiO2微球催化剂,利用XRD、FE-SEM、BET等方法对所制备的催化剂进行了表征,并与溶剂热法制备的样品进行比较,研究不同制备方法对TiO2结构、形貌及催化性能的影响。结果表明,回流法制备的样品为锐钛矿单相微球,晶粒间堆积形成介孔结构,比表面积大;而溶剂热法制备的介孔样品含金红石和锐钛矿两相。以EtOH/HCl为回流溶剂制备的样品孔径约为5 nm,孔径分布窄,比表面积可达496 m2/g,光催化去除Cr（Ⅵ）反应速率快,去除率达到99%。     

Ag@AgCl修饰的具有高活性(001)晶面的锐钛矿相TiO_2的制备和光催化性能研究1

本文采用水热法合成具有高活性(001)晶面的锐钛矿相TiO2微球,利用沉积法将AgCl分散到TiO2微球表面,再通过光化学反应将部分Ag+还原,获得Ag@AgCl等离子体负载的TiO2光催化剂,借助SEM、TEM、UV-Vis DRS等手段对催化剂的结构进行表征,并以酸性红作为模型污染物对样品的光催化性能进行评价。结果表明:经Ag@AgCl修饰后,样品对可见光的响应增强,光生载流子的分离得到有效促进,可见光催化活性有大幅度的提高,对酸性红的降解效率是修饰前的3倍。     

银掺杂介孔二氧化钛的制备及可见光催化性能

以表面活性剂十六烷基三甲基溴化铵(CTAB)为模板、钛酸四丁酯为钛源、硝酸银为掺杂离子前驱体,通过液晶模板辅助溶胶-凝胶法制备银掺杂介孔二氧化钛(Ag/MT),借助于X射线衍射、N2吸附-脱附、差热分析仪、X射线光电子能谱、紫外可见分光光度计、透射电子显微镜等对样品的结构进行了表征,以亚甲基蓝(MB)为目标降解物,探讨了合成产物的可见光催化性能。结果表明:银掺杂降低了介孔二氧化钛(MT)粒径和光生电子-空穴复合率,提高了比表面积和Ti 3+和羟基浓度,使得Ag/MT的光催化活性高于纯MT和P25,银掺杂减小TiO2带隙能,使其具有很高的可见光催化活性。最佳光催化条件为Ag/MT和MB的浓度分别为0.6g/L和1mg/L。     

光催化制备结晶TiO_2介孔薄膜及其性能表征(英文)

提出了一种在室温条件下制备结晶TiO2介孔薄膜的简便方法。首先采用含有罗丹明B的TiO2纳米晶溶胶通过浸渍提拉制备结晶TiO2薄膜,然后将薄膜置于紫外灯下照射,通过TiO2薄膜自身的光催化作用将薄膜中的罗丹明B分解去除,从而形成介孔薄膜。分别采用X射线衍射仪、扫描电子显微镜和透射电子显微镜对样品进行了表征,并考察了薄膜对水的接触角及光催化活性。结果表明:所制备的TiO2介孔薄膜由30～50nm的纳米粒子组成,其晶型为锐钛矿-板钛矿-金红石混晶;适当的罗丹明B添加量有利于介孔形成;由于介孔的作用,TiO2介孔薄膜的亲水性及光催化活性相对于致密TiO2薄膜有显著提高。     

Nd掺杂介孔TiO2光催化剂的制备及其性能研究

本文以十二烷基磺酸钠为模板剂,钛酸四丁酯为钛源,采用水热法制备了介孔TiO2光催化剂和不同摩尔比的Nd掺杂介孔TiO2光催化剂,通过X-射线衍射(XRD)分析、N2吸附-脱附和孔径分布(BET和BJ H)等对其进行表征,并且以甲基橙溶液为目标污染物,考察了所制备样品光催化性能.研究表明,所制备样品均为锐钛矿型结构TiO...     

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.