环氧树脂的静电纺丝

研究了环氧树脂的静电纺丝,考察了纺丝电压、溶液浓度及共混溶剂等参数对纤维直径及分布的影响。研究结果表明:随纺丝电压增大,环氧树脂纤维直径减小,分布区间变窄;随环氧树脂溶液浓度升高,纤维直径增大,在高浓度时,纤维直径会产生分化而形成双峰分布;不同溶剂体系对环氧树脂纤维直径产生影响,在1-甲氧基-2-丙醇(MP)/丁酮(BT)体系中,随BT比例增加,溶液黏度上升,电导率下降,纤维直径增大。     

溶剂对静电纺PA6纤维可纺性的影响

分别用甲酸、六氟异丙醇(HFIP)或甲酸与醋酸(HAc)、N,N-二甲基甲酰胺(DMF)、HFIP的混合溶剂溶解聚己内酰胺(PA6),通过静电纺丝法制备了纳米级的PA6纤维。结果表明:甲酸作为溶剂时,PA6可纺丝溶液质量分数为8%～22%,所纺出的PA6纤维直径为50～300 nm;HFIP作为溶剂时PA6可纺丝溶液质量分数为8%～18%,纤维直径为50～500 nm;甲酸与HFIP,HAc,DMF的混合溶剂对纺丝状态及纤维直径分布的影响均表现为随第2种溶剂的加入,纤维直径的分布变广,平均直径增加;HAc的加入能提高PA6溶液的可纺性。     

PA6静电纺纳米纤维

讨论了PA6静电纺丝工艺,利用扫描电镜(SEM)观察纤维的形态结构,研究了影响PA6静电纺丝 的因素及其对所形成纤维的形态、直径的影响。结果表明,在甲酸溶液中,PA6质量分数为8％、电压值为15 kV、喷丝头到收集板的垂直距离为20 cm是PA6静电纺丝的最佳工艺条件,可得到直径小于100 nm的PA6 纳米纤维。     

明胶超细纤维成形研究

以去离子水为溶剂,采用静电纺丝工艺制备明胶超细纤维。系统探讨了温度、浓度及电纺工艺参数对明胶电纺纤维成形的影响。结果表明：纺丝环境温度的升高有利于获得平均直径较小的纤维;随着明胶溶液质量分数从25％下降到15％,所得明胶纤维平均直径从266．5nm下降到167．7nm,其直径分布也逐渐变窄;随着静电纺丝电压升高,所得纤维直径降低;改变静电纺丝接收距离,所得的纤维直径及其分布均无太大变化。考察了纺丝液中的离子对明胶电纺纤维形貌的影响,发现随着添加的NaGl浓度的增大（0．01～0．5mol／L）,所得明胶纤维的直径呈线性增加（196～390nm）,与纯明胶电纺相比,离子的加入使所得纤维直径分布变宽。     

高相对分子质量PAN纺丝溶液的流变性质

研究了聚丙烯腈 (PAN )纺丝溶液的浓度、温度及聚合物相对分子质量对纺丝溶液的 lgηa ～lgγ流动曲线、粘流活化能、非牛顿指数和结构粘度指数的影响。结果表明 :高相对分子质量聚丙烯腈纺丝溶液具有明显的非牛顿性 ,结构粘度指数随纺丝溶液浓度的升高 ,PAN相对分子质量的增大而增大 ,随纺丝溶液温度的升高、聚合物相对分子质量和浓度的降低而减小。纺制高性能的高相对分子质量PA N纤维宜采用较低的溶液浓度和较高的纺丝温度。     

静电纺丝工艺对二醋酸纤维素纳米纤维形貌及直径的影响

以质量比为2∶1的丙酮/N,N-二甲基乙酰胺混合溶液为溶剂配制二醋酸纤维素(CA)溶液,采用静电纺丝制备CA纳米纤维,探讨了CA浓度、纺丝电压、接收距离和溶液推进速度等工艺条件对CA纳米纤维形貌、直径及其分布的影响。结果表明:CA纳米纤维的直径随CA浓度增加而增大,随纺丝电压增大而减小;适当的接收距离和溶液推进速度可以获得直径较小且分布均匀的纤维;当CA质量分数为11%、纺丝电压为30 k V、接收距离为15 cm、溶液推进速度为0.010 m L/min时,纺丝效果好,纤维平均直径约130 nm,且直径分布较均匀。     

静电纺丝热塑性聚氨酯纳米纤维的制备

将N,N-二甲基甲酰胺（DMF）和四氢呋喃（THF）按体积比0：4、1：3、2：2、3：1、4：0混合作为溶剂,确定配比后,在不同浓度、电压下对热塑性聚氨酯（TPU）溶液进行静电纺丝。结果表明,DMF与THF的体积比对聚氨酯静电纺丝纤维的形貌、直径及其均匀性有明显影响,当混合溶液体积比为2：2,浓度为0．18g／mL,电压为26kV时,TPU纺丝液纺丝效果最佳,得到最理想的纤维;纤维直径随DMF含量的增多而减小,但当DMF含量过多时,纤维上容易出现液滴,纤维形貌变差;TPU纺丝液浓度增大,纤维直径增大;电压增大,纤维直径减小。     

钢丝毛刷辊式静电纺PVA纳米纤维

设计了一种批量制备连续纤维的钢丝毛刷辊静电纺丝装置,研究了固定距离时溶液浓度及电压对毛刷PVA溶液静电纺丝产量的影响。考察了不同浓度PVA在不同纺丝距离、纺丝电压、毛刷转速下的纤维直径分布与纤维形貌。借助扫描电镜对制得的纳米纤维形貌进行观察,并应用Nano Measurer软件对纤维的直径及其分布进行了测量统计。综合考察结果,得出最佳的纺丝溶液浓度为12%,接收板距离为10 cm,电压为40 k V。     

含银PA6纳米纤维的制备及抗菌性能研究

以次磷酸钠还原硝酸银制得银溶胶,按不同比例加入到质量分数为12%的聚己内酰胺(PA6)/甲酸溶液中,通过静电纺丝制备含银PA6纳米纤维毡,分析了纤维的表面形貌和抗菌性能。结果表明:当纤维中银质量分数为0.1%时,PA6纳米纤维对大肠杆菌的抑菌率达95%以上。扫描电镜和原子力显微镜分析表明,含银PA6纳米纤维比PA6纳米纤维平均直径稍粗,直径分布更集中,纤维直径为80～100 nm,但其表面有明显的褶痕,粗细节较多,不如PA6纳米纤维光滑。     

聚乙烯醇静电纺丝纳米纤维的制备及形貌研究

利用静电纺丝技术制备聚乙烯醇（PVA）纳米纤维材料,通过正交试验调节制备过程中纺丝电压、纺丝距离和纺丝溶液浓度等工艺参数,探究其对PVA纳米纤维直径大小、直径分布以及纤维形貌的影响。结果表明,影响纳米纤维形貌的主要因素排序是纺丝溶液浓度＞纺丝距离＞纺丝电压,并确定最优水平组合为纺丝电压为20 kV,PVA纺丝溶液浓度为6 %(质量分数,下同),纺丝距离为12 cm。     

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.     

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。     

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.     

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.     

ICP-MS法测定地球化学样品中As、Cr、Ge、V等18种微量痕量元素的研究

建立了测定地球化学样品中包括As、Cr、Ge、V等18种微量、痕量元素的ICP-MS方法。地化试样用HF-HNO3混酸分解后,以1 1 HNO3溶解干渣。由于制样不使用盐酸,避免了Cl对As、Cr、Ge、V的质谱干扰。用国家一级地球化学标准物质GBW 07309制备溶液优化仪器工作参数,并用于校准。方法测定限(6s)为:0.007~6.4μg/g,精密度(RSD%,n=12)为:29%~9.4%,经过国家一级地球化学标准物质的分析验证,结果与标准值吻合。方法已应用于国土资源调查的试样分析。