微生物生长载体磁性PCL/PAN复合纳米纤维膜的制备及性能研究

以聚己内酯(PCL)和聚丙烯腈(PAN)为溶质,N,N-二甲基甲酰胺(DMF)和三氯甲烷(TCM)为溶剂,加入磁性四氧化三铁(Fe_3O_4)纳米粒子,利用静电纺丝技术制备磁性PCL/PAN复合纳米纤维膜,将其作为微生物生长载体应用于污水处理中。试验结果表明:PAN的加入改变了纤维内部结晶的位置,复合纳米纤维直径较小,直径分布较均匀,基本无粘连现象;复合纳米纤维膜力学性能较好,其作为微生物生长载体对污水处理的效果较好,可重复利用。     

聚丙烯腈/氧化铁纳米粒子复合纳米纤维的制备及表征

利用静电纺丝技术制备了一种聚丙烯腈(PAN)/氧化铁(Fe_2O_3)纳米粒子复合纳米纤维。不同分子量的PAN得到不同直径的纤维薄;将PAN的N,N-二甲基甲酰胺溶液(DMF)与纳米Fe_2O_3混合得到PAN/Fe_2O_3溶液,然后利用静电纺丝技术制备PAN/Fe_2O_3纳米粒子复合纳米纤维;将静电纺丝制备的PAN纳米纤维膜与氯化铁(FeCl_3)溶液在不同p H条件下水热合成PAN/Fe_2O_3纳米粒子复合纳米纤维。采用扫描电子显微镜(SEM)、热重分析仪(TGA)对纳米纤维膜进行表征。结果表明:静电纺丝制备的PAN纳米纤维在水热条件下可以一定程度上克服Fe_2O_3纳米粒子易团聚问题。     

静电纺丝法制备PVA/Fe_3O_4磁性纳米纤维

将纳米Fe3O4磁性颗粒加入含分散剂的聚乙烯醇水溶液中,选取卵蛋白粉为分散剂,利用静电纺丝制备磁性纳米纤维。通过扫描电镜(SEM)和透射电镜(TEM)表征纤维形貌和分析溶液中粒子分散情况,选用古埃磁天平对纳米纤维毡进行磁性测试。实验结果表明,所制得的复合纳米纤维成纤性良好,粒子分散均匀,且具有一定的磁性。     

电纺PAN纳米纤维的碳化工艺研究

研究了电纺方法制备的聚丙烯腈(PAN)纳米纤维的碳化工艺。利用热重/差热(TG/DTA)分析仪对其升温过程中的物理化学反应过程进行了分析,讨论了在空气和氮气两种氛围内原纤维的热氧化、分解过程,发现在290℃附近PAN纤维发生强烈的氧化反应,温度达到930℃时,原纤维几乎完全转化为碳纤维。利用扫描电镜(SEM)和Raman光谱仪对不同温度下稳定化和碳化处理得到PAN基碳纤维进行了深入的研究,得到了电纺PAN原纤维碳化的工艺规律。     

PAN-O/MMT复合纳米纤维膜的制备及染料吸附性能

利用静电纺丝法制备了含有不同质量分数(0、1%、3%、5%)有机改性蒙脱土(O/MMT)的聚丙烯腈复合纳米纤维膜,通过亚甲基蓝吸附分析比较了纤维膜的吸附性能。利用粘度、电导率、表面张力分析了MMT的含量对纺丝液性质的影响,利用扫描电子显微镜分析了不同比例O/MMT的加入对所制备的复合纳米纤维的形貌结构的影响,傅里叶变换红外光谱分析结果证实了O/MMT和PAN形成了纳米复合结构,同时借助热重分析仪分析了O/MMT的加入对复合纳米纤维膜热性能的影响。结果表明,随着O/MMT含量的增加,纤维变细、珠节增加,纤维膜的亚甲基蓝吸附能力也同时提高。     

聚丙烯腈前驱体的优化及其中空碳纳米纤维的制备

为制备力学性能较好的聚丙烯腈(PAN)中空碳纳米纤维,首先通过正交试验研究了PAN聚合参数对聚合反应的影响,然后选取适宜于纺丝的PAN进行同轴静电纺丝、预氧化、碳化,对得到的中空碳纳米纤维进行表征。结果表明,引发剂用量(A)对PAN相对黏均分子质量的影响最大;第二单体衣康酸浓度(B)对PAN环化放热的影响最大;第三单体丙烯酸甲酯浓度(C)对PAN聚合收率的影响最大。SEM分析结果表明,PAN中空碳纳米纤维横截面具有明显的中空结构,纤维表面较为致密。BET测试结果表明,PAN中空碳纳米纤维的孔容为0. 069 69 cm3/g,比表面积为55. 719 m2/g。     

静电纺聚丙烯腈基碳纳米纤维的制备及电学表征

利用聚丙烯腈(PAN)及三甲基甲酰胺(DMF)制备静电纺纺丝液:纺制出的纤雏在N2保护下,于500～1500°C范围内进行高温分解,持续约1h后便得到碳纳米纤维.利用SEM分析了纤维的形态结构,未经喷金的碳化PAN纳米纤维的SEM照片表明制备的碳纤维具有导电性能.利用热重分析法(TGA)分析了纤维的热性能.利用间接的四探针方法测量了纳米纤维毡的导电性能,发现导电性会随着高温分解温度的增加而急剧增加.     

PAN/TiO_2纳米纤维膜的制备及性能研究

将聚丙烯腈(PAN)、纳米二氧化钛(TiO_2)溶于N,N-二甲基甲酰胺中,配制成混合溶液,通过静电纺丝制备PAN/TiO_2纳米纤维膜,研究了纳米TiO_2含量对PAN/TiO_2纳米纤维膜的结构与性能的影响。结果表明:随着TiO_2含量增加,PAN/TiO_2纳米纤维膜的平均直径稍许增大,但其外观形貌越来越差;TiO_2的加入对PAN/TiO_2纳米纤维膜的分子结构没有影响;随着TiO_2含量的增加,PAN/TiO_2纳米纤维膜的玻璃化转变温度和熔融温度升高,表面接触角下降,即耐热性能和润湿性能提高。     

ZnO/PAN基纳米碳纤维膜的制备及其光催化性能的研究（英文）

采用N,N-二甲基甲酰胺(DMF)为极性溶剂溶解醋酸锌(Zn(Ac)_2·2H_2O),然后加入聚丙烯腈(PAN)制得前驱体溶液,采用静电纺丝法制备PAN/Zn(Ac)_2复合纳米纤维膜,将PAN/Zn(Ac)_2复合纳米纤维膜在真空管式炉中经过高温煅烧得到PAN基碳纤维/氧化锌(CF/ZnO)纳米纤维膜,以CF/ZnO纳米纤维膜为光催化剂,亚甲基蓝为污染物,进行光催化降解实验,研究了Zn(Ac)_2含量对PAN/Zn(Ac)_2复合纳米纤维形貌、性能的影响,以及CF/ZnO纳米纤维膜的光催化性能。结果表明:Zn(Ac)_2的掺入并未对PAN的化学结构产生影响,二者属于物理结合,Zn(Ac)_2能较均匀地分布在纤维的内部;随着Zn(Ac)_2含量的增加,CF/ZnO纳米纤维膜对亚甲基蓝的降解率会提高,当Zn(Ac)_2质量分数(相对PAN)为60%时,可见光照射80 min后CF/ZnO纳米纤维膜对亚甲基蓝的降解率达到91.6%。     

磁场辅助静电纺PAN纳米纤维有序度的研究

采用磁场辅助静电纺丝法制备了有序聚丙烯腈(PAN)纳米纤维,分析了PAN/二甲基甲酰胺(DMF)溶液浓度、纺丝电压、注射速度、磁铁间距和溶剂DMF及DMF与二甲基亚砜(DMSO)混合溶剂等因素对PAN纤维有序度的影响。结果表明:随着PAN/DMF溶液中PAN浓度增大,PAN纤维有序度逐渐增大;注射速度对纤维有序度影响不明显;随着纺丝电压和磁铁间距增大,PAN纤维有序度先增大后减小;DMSO的加入,使溶液可纺性降低,不利于纤维有序排列;对于PAN/DMF溶液体系,适宜的磁场辅助静电纺丝的工艺参数为PAN质量分数12%,纺丝距离12 cm,电压14 k V,注射速度0.5 m L/h,磁铁间距2.5 cm,纺丝得到的PAN纳米纤维的有序度为92%。     

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.     

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.     

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。