混晶结构纳米TiO2粉体的制备与性能表征

以钛酸丁酯为前驱体,采用溶胶-凝胶法制备了具有混晶结构的二氧化钛纳米粉体材料.研究了煅烧温度、pH值对二氧化钛晶型的影响,并用X射线衍射(XRD)、场发射扫描电镜(SEM)、分光光度计等对其进行测试表征.光催化降解性能测试表明:同一pH值下,随着温度的升高,金红石型TiO2的含量增加,锐钛矿型TiO2的含量减少.随着溶胶pH值的减小,TiO2由锐钛矿相向金红石相的转变温度也随之降低.光催化降解亚甲基兰实验表明,锐钛矿含量为76.12%、金红石含量为23.88%时1h内光降解率达98%.     

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。     

TiO2负载玄武岩纤维毡复合材料的制备及其光催化性能

采用浸渍法将热蚀处理后的玄武岩纤维毡浸渍在Ti溶胶中负载成膜,在300 ～ 650℃烧结制备出TiO2负载玄武岩纤维毡光催化复合材料.利用XRD和SEM对TiO2和纤维毡进行了表征,并通过甲基红配制的模拟印染废水的降解考察了浸渍次数和烧结温度对光催化性能的影响.实验表明:随着玄武岩纤维毡在Ti溶胶中浸渍次数的增加,TiO2负载率增加,甲基红降解率具有先急剧增加后缓慢减小的趋势,TiO2负载率为4.83％时降解率达到极值98.58％.随着烧结温度升高,TiO2晶型由无定形态→锐钛矿→锐钛矿+金红石混晶转变,当锐钛矿与金红石混晶比例为9∶1 ～4.5∶1时,光催化性能较好,随着金红石相增加,甲基红降解率大幅降低.     

纳米TiO_2的低温制备及晶相控制研究

以钛酸丁酯为前躯体,在低温(40℃)下制备TiO2薄膜,并评价其光催化活性。结果表明,制备的TiO2薄膜不需经过高温处理,就有较好的光催化活性;XRD分析表明,未经过热处理的样品,随着反应温度的提高,得到的TiO2粒径变大,经450℃处理2 h的样品,金红石含量随反应温度提高而减少。醋酸的加入不仅能抑制板钛矿相的生成,而且提高了锐钛矿相向金红石相转变的温度。     

Pb2+掺杂TiO2的光催化性能研究

以钛酸丁酯和硝酸铅为原料,用溶胶-凝胶法制备了Pb2+掺杂纳米TiO2粉体,讨论了不同掺杂浓度、不同热处理温度样品在催化降解刚果红染料实验中的光催化活性,分析了Pb2+掺杂TiO2样品的相组成、晶胞参数和晶粒大小对光催化活性的影响.结果表明:Pb2+掺杂能够使锐钛矿向金红石的转变温度向高温方向移动,并且细化了晶粒,实验最佳掺杂浓度为100∶2.0,最佳热处理温度为700℃;Pb2+掺杂的TiO2的锐钛矿相是影响光催化活性的决定性因素.     

纳米TiO_2-WO_3的制备及对甲醛的光催化降解

采用溶胶-凝胶法制备TiO2 WO3纳米复合催化剂,对浓度为3 3×10-3mol/L的甲醛溶液进行光催化,考察了不同条件对其光催化降解的影响。结果表明,相同的焙烧温度下,WO3掺杂能抑制粒径的长大;焙烧温度升高,TiO2金红石相质量分数增加,粒径变大;WO3掺杂量为w(WO3)=3%、600℃焙烧时,金红石相质量分数为13 5%,光催化活性最高,甲醛光催化1 5h后降解率达到64%,比纯TiO2光催化活性高出79 4%。     

明胶对纳米二氧化钛相变和光催化活性的影响

以明胶为分散剂采用溶胶-凝胶法制备了纳米晶TiO2粉末.通过XRD、TG-DTA、AFM、N2吸附-解吸等手段,考察了明胶对TiO2煅烧过程中相变和平均粒径的影响;用光催化降解甲基橙检测了明胶用量对样品光催化活性的影响.结果表明：明胶的存在抑制了TiO2由无定形向锐钛矿的相变,降低了锐钛矿向金红石的相变温度;同时,TiO2纳米晶的平均粒径也随明胶用量的增加而减小.600℃煅烧样品的光催化活性随明胶用量的增加而提高;800℃煅烧样品在mG：mTBOT（明胶与钛酸四丁酯的质量比）=1：8时,具有最高的光催化活性.     

纳米TiO_2的制备及其光催化性能

以钛酸四丁酯为原料,采用溶胶 凝胶法制备了纳米级TiO2颗粒,通过甲苯在样品上的光催化氧化过程评价了样品的光催化活性。考察了制备过程中的焙烧温度对样品颗粒的晶型、粒径和光催化性能的影响。X射线衍射结果表明,焙烧温度低于500℃时得到的样品都是锐钛矿型TiO2,700℃下得到的已基本是金红石型;随着焙烧温度的升高样品的粒径增大,光催化活性下降;甲苯在TiO2上的气相光催化氧化符合一级反应规律。     

溶胶-凝胶制备TiO2空气净化特性研究

利用XRD等手段对以钛酸四丁酯为原料采用溶胶-凝胶法制备的TiO₂纳米粒子的表面特性及其对空气环境中乙醛的光催化降解性能进行了测定。结果表明，乙醇与钛酸四丁酯体积比、溶胶pH、加水量和焙烧温度等对催化剂降解乙醛的活性有显著影响。在实验条件范围内，较短胶凝时间制备出的纳米粉末晶粒尺寸较小，活性较高。焙烧温度不但影响TiO₂粉末的粒径，而且对晶型的组成也有影响。锐钛矿晶型的光催化活性明显高于金红石晶型，锐钛矿型向金红石型转变的临界温度在（500～600） ℃。实验得到TiO₂最佳制备条件为：V(乙醇)∶V(钛酸四丁酯)=4、溶胶pH=3.0、加水量4 mL和焙烧温度(400～500) ℃。     

纳米TiO_2的制备及其在处理含DNBA废水中的应用研究

在室温条件下,以钛酸四丁酯水解制备了无定形Ti(OH)4胶体,然后在酸性条件下,加入分散剂,搅拌、老化16h,加入甲苯,用油水分离器除去水和大部分甲苯,60℃真空干燥,得到纳米TiO2粉末。在400℃煅烧3h即得到锐钛矿晶型TiO2;500℃煅烧3h即有部分锐钛矿晶型TiO2转化为金红石晶型TiO2;700℃煅烧3h主要以金红石晶型存在;在800℃煅烧3h完全转化为金红石晶型,粒径20～50nm。室温条件下,金红石晶型的纳米TiO2粒子,能够使3,5 二硝基苯甲酸(DNBA)发生光催化降解反应,DNBA经光催化反应160min后,其浓度由原来的2×10-4mol/L降为9 7×10-6mol/L。表明金红石晶型的纳米TiO2粒子对DNBA具有很高的光催化活性。H2O2能显著提高DNBA的光催化降解速率。     

Sapindaceae,cyanolipids, and bugs

Scentless plant bugs (Heteroptera: Rhopalidae) are so named because adults of the Serinethinae have vestigial metathoracic scent glands. Serinethines are seed predators of Sapindales, especially Sapindaceae that produce toxic cyanolipids. In two serinethine species whose ranges extend into the southern United States,Jadera haematoloma andJ. sanguinolenta, sequestration of host cyanolipids as glucosides renders these gregarious, aposematic insects unpalatable to a variety of predators. The blood glucoside profile and cyanogenesis ofJadera varies depending on the cyanolipid chemistry of hosts, and adults and larvae fed golden rain tree seeds (Koelreuteria paniculata) excrete the volatile lactone, 4-methyl-2(5H)-furanone, to which they are attracted.Jadera fed balloon vine seeds (Cardiospermum spp.) do not excrete the attractive lactone. Loss of the usual heteropteran defensive glands in serinethines may have coevolved with host specificity on toxic plants, and the orientation ofJadera to a volatile excretory product could be an adaptive response to save time.Mention of a commercial product does not consititute an endorsement by the USDA.     

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.     

2008～2009年世界塑料工业进展

收集了2008年7月～2009年6月世界塑料工业的相关资料,介绍了2008～2009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、环氧树脂、不饱和聚酯树脂)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。     

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.     

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.