草莓状银/聚苯乙烯-丙烯腈复合微球制备及其催化性能

以可聚合单体对苯乙烯磺酸钠(Na SS)作稳定剂,采用两步阴离子稳定分散聚合法,制备了单分散聚苯乙烯-丙烯腈P(St-AN)共聚微球,研究了丙烯腈单体加入时间对聚合物微球粒径及其分布的影响。并以微球为模板通过化学沉积法得到了分布均匀、单分散草莓状的Ag/P(St-AN)复合微球。通过傅里叶红外光谱、X射线衍射、扫描电镜和紫外-可见光谱对复合微球的组成、结构、形貌及催化性能进行了表征。结果表明,反应后1~3h补加丙烯腈可以得到600~800 nm单分散模板微球。得到的Ag/P(St-AN)复合微球表面具有较均一的结构,纳米银粒子具有面心立方结构,在微球表面有较好的分散性及稳定性,同时Ag/P(St-AN)复合微球对硼氢化钠(Na BH4)还原对硝基苯酚(4-NP)具有较高的催化活性。     

聚(苯乙烯-甲基丙烯酸)/银复合微球的制备与表征

本文采用单分散的聚(苯乙烯-甲基丙烯酸)(PSMAA)微球作为基材,在其表面通过静电作用吸附银氨离子([Ag(NH_3)_2]~+),通过聚乙烯吡咯烷酮(PVP)还原成银(Ag)纳米粒子,形成PSMAA/Ag微球。采用红外光谱(FTIR)、透射电镜(TEM)和X射线衍射(XRD)对PSMAA/Ag复合微球进行了表征,结果表明:Ag纳米粒子较为均匀地分布于PSMAA微球表面,Ag纳米粒子的粒径大约为15~40 nm。     

制备球径可控的单分散PMMA微球

单分散聚甲基丙烯酸甲酯(PMMA)微球是由甲基丙烯酸甲酯加聚而成的一种聚合物,在各领域有广泛应用。PMMA微球尺寸在很大程度上影响其纳米材料特性。采用无皂乳液法合成粒径可控(300~500)nm的纯聚甲基丙烯酸甲酯微球。以甲基丙烯酸甲酯在水溶液体系中为单体,2,2-偶氮二(2-甲基丙基咪)二盐酸盐为引发剂,在无任何附加组分的情况下,生成单分散聚甲基丙烯酸甲酯微球。通过调整反应参数,即反应温度、搅拌速率、引发剂用量和初始单体用量,探究其对PMMA微球的粒径及多分散的影响。结果表明,随着反应温度、引发剂浓度升高,微球球径减小而多分散系数增加;与之相反,单体浓度与搅拌速率增大,微球的尺寸和多分散系数增大。因此,在控制变量条件下可以成功制备球径可控和尺寸均一的单分散性微球。     

单分散氢氧化钙/聚苯乙烯微球的制备与表征

以葡萄糖水溶液为反应介质,在氧化钙消化成氢氧化钙的过程中,加入苯乙烯单体和引发剂,采用原位悬浮聚合法成功制备了聚苯乙烯(PS)包覆氢氧化钙[Ca(OH)2]形成Ca(OH)2/PS微球.考察了葡萄糖水溶液、苯乙烯、稳定剂聚乙烯醇以及反应温度对单分散Ca(OH)2/PS微球的粒径及粒子分散系数的影响,得出较佳合成条件.在较佳条件下制备的Ca(OH)2/PS微球平均粒径为30～40 μm,粒子分散系数为0.08～0.10.扫描电镜照片表明,Ca(OH)2/PS具有良好的球形度,表面光滑、无破损.红外光谱表征显示,产物为Ca(OH)2/PS微球.     

无皂乳液聚合法制备亚微米级单分散聚苯乙烯微球

采用无皂乳液聚合法制备了亚微米级聚苯乙烯(PS)微球,考察了苯乙烯(St)单体浓度、引发剂过硫酸钾(K2S2O8)浓度、离子强度(氯化钠浓度)与PS微球粒径及其分布的关系。然后通过加入微量乳化剂或β-环糊精对无皂乳液聚合法进行改进,研究了改进效果。结果表明,PS微球的粒径随St单体浓度和氯化钠浓度的增加而增加、随K2S2O8浓度的增加而减小,通过调节这3种原料的浓度,可制得粒径在450~1000 nm且单分散系数小于0.08的PS微球,但产品收率较低,仅为30%左右。在相同的合成条件下,加入微量乳化剂可制得粒径在100~350 nm且单分散系数小于0.05的PS微球,产品收率提高到75%左右;加入微量β-环糊精可制得粒径在300 nm左右且单分散系数小于0.08的PS微球,产品收率可达80%且反应时间大幅缩短,由原来的12 h缩减到5 h。     

高度单分散聚硫氰基倍半硅氧烷微球的可控合成及其吸附性能研究

在水溶液中,以3-硫氰基丙基三乙氧基硅烷(TCPTES)为前驱体,氨水为催化剂,通过一步法成功合成了不同粒径、高度单分散的聚硫氰基倍半硅氧烷(PTSQ)球形纳米粒子.通过扫描电子显微镜(SEM)、转靶X射线衍射仪(XRD)、傅里叶变换红外光谱(FTIR)、热重(TG)分析对产物的形貌、结构及热性能进行了表征,此外,通过原子吸收光谱(AAS)研究了产物对Cd2+的吸附性能.研究结果表明,通过调节前驱体TCPTES与催化剂氨水的浓度能够可控地制备出粒径为0.45 ～ 1.20 μm的高度单分散PTSQ微球.当PTSQ粒子用于Cd2+的吸附时,其吸附量最高达0.563 mmol/g,几乎为纯二氧化硅微球的两倍.     

SiO2用量对单分散聚脲多孔微球的影响

通过沉淀聚合,以异佛尔酮二异氰酸酯(IPDI)为单体,质量比为3:7的水与丙酮的混合溶液为溶剂,Si O2纳米颗粒为模板制备Si O2/聚脲复合微球,用Na OH溶液刻蚀掉Si O2后得到聚脲多孔微球。固定IPDI用量,改变模板Si O2纳米颗粒的用量制取聚脲多孔微球,用扫描电子显微镜观察微球的形貌,并对聚脲多孔微球的粒径、单分散性进行了测算。结果表明,不加Si O2纳米颗粒制得的实心聚脲微球粒径不均一,加入Si O2纳米颗粒后,制得的聚多孔脲微球的粒径增大,单分散性提高。     

SiO2单分散溶胶微球制备的工艺条件研究

在乙醇介质中,以氨作为催化剂,正硅酸乙酯作为硅源,制备了单分散的二氧化硅溶胶微球。通过激光粒度分析仪及透射电镜测定溶胶粒子的大小。研究了不同工艺参数如催化剂和水的量、硅源的量以及溶剂的类型对二氧化硅粒子大小及形貌的影响,并考察了粒子的形成机理。结果显示:随着氨浓度的升高,溶液初始解离的[OH-]增大,二氧化硅粒子的粒径增大;随着硅源浓度的增加,溶液中水解的中间产物增加,二氧化硅微球的粒径显著增加;在r(水/正硅酸乙酯)值远大于4的情况下,随着初始加入水量的增加,二氧化硅微球的粒径有所增加,但当水量太多时,粒径反而下降;使用不同溶剂作为制备二氧化硅的介质,在丙醇和丁醇中二氧化硅严重团聚,没有得到单分散微球。     

羧基改性单分散二氧化硅纳米球的制备与表征

以浓氨水为催化剂、四乙氧基硅烷(TEOS)为原料,利用Stober溶胶-凝胶法制得二氧化硅(SiO2)微球。粒度仪测试结果表明,SiO2微球粒径为30～100nm,其平均粒径随着催化剂用量的增加而增大。进一步用γ-氨丙基三乙氧基硅烷对SiO2纳米球进行表面改性,后与苯偏三酸酐反应,得到羧基改性的SiO2纳米球。利用TEM、FT-IR对羧基改性纳米球进行表征。结果表明,改性过程对SiO2纳米球的粒径无影响,羧基通过化学键结合在SiO2纳米球表面。     

纳米二氧化硅改性纸/塑复合用聚氨酯胶粘剂的研究

以γ-氨丙基三乙氧基硅烷(KH-550)、正硅酸乙酯(TEOS)为原料,采用溶胶-凝胶法制备了改性纳米Si O2(二氧化硅);然后将其引入至PU(聚氨酯)胶粘剂中,制备了纸/塑软包装复合用无溶剂PU胶粘剂。研究结果表明:硅烷偶联剂(KH-550)已成功接入至纳米Si O2结构中,改性纳米Si O2的单分散性良好且粒径分布在100~200 nm范围内;当w(改性纳米Si O2)=0.8%(相对于胶粘剂总质量而言)时,胶粘剂的剥离强度(为420 N/m)相对最大。     

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.     

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。     

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.     

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.     

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.     

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.