基板温度对常压化学气相沉积法制备TiO2复合薄膜性能的影响

以Ti(OC3H7)4为先驱体,SnO2:F镀膜玻璃为基板,采用常压化学气相沉积法制备了TiO2/SnO2:F复合薄膜.用扫描电镜、X射线衍射、紫外-可见-近红外透射光谱等手段对样品的物相和性能进行了研究.结果表明:金红石相的SnO2:F底膜促进了TiO2金红石相的形成;当基板温度为480 ℃时,TiO2/SnO2:F复合薄膜出现针状结构,但随着基板温度继续升高,针状结构消失.样品的可见光透过率随基板温度而变化,其值为60%～90%,基本满足建筑物的采光要求.当基板温度为530 ℃时,TiO2/SnO2:F复合薄膜的光催化性能最好.     

脉冲激光沉积法制备ZrW_2O_8薄膜(英文)

采用纯ZrW2O8陶瓷靶材,以脉冲激光沉积法在石英基片上沉积并退火处理后制备了ZrW2O8薄膜.利用X射线衍射仪、X射线光电子能谱 仪和扫描电子显微镜观察和确定r薄膜结构、化学组分和表面形貌,用划痕仪、表面粗糙轮廓仪测量了薄膜与基片之间的结合力和薄膜厚度.结果表明:脉冲激光沉积的薄膜为非晶态,膜层物质各元素之间的化学计量比与靶材成分一致;衬底未加热沉积的薄膜表而粗糙度较大,衬底温度为650℃ 时,薄膜表面平滑致密,粗糙度明显降低:非晶膜在1200℃密闭退火热处理3 min后淬火得到立方相ZrW2O8薄膜,退火后的薄膜品粒较大,同时 还出现一些沿晶界和晶内的裂纹缺陷.随着退火温度升高,薄膜与基片的结合力降低.     

热处理温度对纳米TiO2薄膜光催化性能的影响（英文）

以TiCl4为原料,氨水为沉淀剂,采用水解沉淀法在硅藻土基多孔陶瓷上负载了TiO2薄膜。通过热重–差示扫描量热分析、X射线衍射对经不同温度热处理的样品进行了表征,探讨了热处理温度对TiO2晶相、晶粒尺寸等因素的影响。以甲醛为目标降解物,考察了热处理温度对TiO2光催化性能的影响。结果表明:随着热处理温度的升高,薄膜由锐钛矿型转变为金红石型,TiO2晶粒尺寸由6.5 nm(350℃)增加到52.8 nm(1 000℃);经750℃热处理的薄膜组成中出现金红石相,温度升至1 000℃,锐钛矿型TiO2完全消失;经550℃热处理的TiO2光催化效果最好,在1 m3环境仓内,8 W紫外灯下光照240 min,初始浓度0.526 mg/m3的甲醛去除率达到95.2%。     

镀SiO2膜玻璃基片上化学气相沉积法制备SnO2:Sb薄膜

采用化学气相沉积法在镀有SiO2膜的钠钙硅玻璃基片上制备了Sb掺杂SnO2(antimony-doped tin oxide,ATO)薄膜.研究了基板温度、基板输送速度和氮气流量对ATO薄膜结构和性能的影响.用X射线衍射仪、扫描电镜、X射线光电子能谱仪、紫外-可见光谱仪、双光束红外分光光度计对薄膜的结构、形貌和成分进行了表征.结果表明:沉积温度为490 ℃以上时,薄膜主要以四方相金红石结构存在.随着基板输送速度的提高,薄膜择优取向由(110)转变为(200).薄膜中掺杂的Sb以Sb5 的形式存在;当基板温度为530 ℃时,薄膜表面的C没有完全燃尽,以C-O形式存在于薄膜中.薄膜的可见光透过率随基板温度的升高而增大.具有(110)择优取向的薄膜的红外反射性能较好.     

相组成对TiO_2薄膜生物活性的影响(英文)

以钛酸正丁酯(Cl6H36TiO4)为原料,采用溶胶-凝胶法制备了TiO2薄膜。TiO2薄膜分别在300,400,500,600,800℃下于空气中热处理2h。将热处理前后的TiO2薄膜浸泡于模拟体液(simulated body fluids,SBF)中,考察其表面诱导类骨磷灰石形成的能力。利用X射线衍射、扫描电子显微镜、能谱仪、Fourier变换红外光谱等测试手段表征TiO2薄膜和磷灰石的微观结构。结果表明:原始和经300℃热处理的TiO2薄膜为无定形结构;随着煅烧温度的升高,TiO2由无定形结构向锐钛矿相转变;温度升高至800℃后,锐钛矿相完全转化为金红石相。TiO2薄膜经SBF浸泡7d后,经400,500,600,800℃热处理的TiO2薄膜表面生成含有碳酸根的羟基磷灰石,且其Ca与P的摩尔比为1.52,接近人体骨骼的钙磷比(1.67)。而原始和经300℃热处理的TiO2薄膜无此现象发生,这说明TiO2薄膜的晶型对其生物活性具有重要影响,锐钛矿和金红石相TiO2薄膜均具有诱导磷灰石生成的能力。     

纳米二氧化钛薄膜的制备及性能研究

用溶胶-凝胶法在清洁的玻璃表面成功制备了均匀透明的纳米TiO2薄膜,并用X射线衍射仪,扫描电镜,红外光谱仪和接触角测定仪等对薄膜的结构和性质进行了研究.结果表明:薄膜由晶粒大小为20～45 nm的TiO2球型颗粒组成,膜表面均匀,结构致密,具有平整的组织结构;随热处理温度的增加,TiO2薄膜的晶相由无定型态转变成锐钛矿,最后在850℃热处理后完全转变成金红石相,且TiO2薄膜在经过紫外光的照射后亲水能力增强.     

TiO_2纳米薄膜微结构及光催化性能研究

以钛酸丁酯Ti(OBu)4为原料,采用溶胶-凝胶法在普通钠钙玻璃表面制备了TiO2纳米薄膜,用XRD、UV-VIS等技术对薄膜微结构及紫外吸收性能进行了表征,选用食用油光催化降解为模型对TiO2薄膜光催化性能进行了评价。探讨了退火温度对薄膜晶相结构及其光催化活性的影响,450℃退火处理的薄膜呈锐钛矿和金红石型混晶结构,锐钛矿相平均晶粒尺寸为28.8 nm,金红石相平均晶粒尺寸为40.4 nm,700℃退火后为纯金红石相。焙烧温度在450—490℃光催化活性较为理想,480℃附近光催化活性达到最高。涂膜层数增加,光催化活性增强,8层膜的光催化活性最高。     

纳米TiO_2薄膜的制备及其光谱特性研究

采用溶胶凝胶法和旋转涂膜工艺,以普通玻璃为衬底,制备均匀、透明的TiO2纳米薄膜。利用X射线衍射仪(XRD)、原子力显微镜(AFM)和紫外可见光谱(UV/vis)对TiO2进行表征。通过500℃、600℃、700℃、800℃和900℃恒温烧结2h后XRD测试表明:经500°C退火得到TiO2粉末为锐钛矿晶相,800℃转化为金红石相结构,900℃出现了金红石相与板钛矿相的混合晶相。通过AFM观测,薄膜的平均粗糙度为1.71nm。通过紫外可见光谱分析,探讨了影响TiO2纳米膜厚度和禁带宽度度的各种因素。结果表明:涂膜次数、热处理温度等将直接影响二氧化钛薄膜的紫外可见光谱和禁带宽度。     

退火温度对氮化钽薄膜电阻器性能的影响

通过反应直流磁控溅射法在Si片表面沉积氮化钽(Ta N)电阻薄膜,并在空气中进行退火,系统研究了退火温度对薄膜的物相组成、微观形貌、电阻性能的影响。结合X射线衍射(XRD)物相分析、扫描电子显微镜(SEM)形貌分析及电阻性能测试结果,Ta N薄膜最佳退火温度为400~450℃,在此温度范围内退火,可制备出与硅基底附着良好、较小电阻温度系数(TCR,≤±100×10-6/℃)、2000 h老化电阻变化率(ACR)约0.43%的高稳定Ta N薄膜电阻器。     

溶胶-凝胶法制备亲水性TiO2/SiO2 薄膜的相转变行为研究

采用溶胶-凝胶法在玻璃表面制备了厚度约240nm的亲水性TiO2/SiO2薄膜,用差热分析(DTA)、红外光谱(FT-IR)和X射线衍射分析(XRD)研究了薄膜的热演化过程及晶相转变行为,结果表明:在500℃热处理1h的TiO2膜呈锐钛矿相,TiO2/SiO2复合膜则为非晶态,SiO2的加入使析出锐钛矿晶体所需的温度升高,且提高了TiO2由锐钛矿向金红石结构转变的温度;此外,随薄膜中SiO2含量增多,薄膜的亲水性增强.     

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.