纳米絮状铁纤维的制备及性能测定

用化学气相热解制备纳米絮状铁纤维,通过X射线衍射仪、扫描电子显微镜、震动样磁强计、X射线能谱仪、微波矢量网络分析仪对材料的性能进行了表征。结果表明:制备的材料为体心立方结构的α Fe絮状纤维,研磨成微粉后,微观下仍然呈纤维状,自然降温的比饱和磁化强度(σs)为128～187emu·g-1,快速降温铁纤维的矫顽力(Hc)比自然降温的铁纤维高12倍;纤维的平均直径0 35μm,铁粒子的晶粒尺寸为6 85～15 18nm;在微波X波段有强吸收衰减作用,反射率小于-10dB,面密度为1 72～2 2kg/m2。     

羰基热分解磁场引导制备多晶铁纤维原理分析

多晶铁纤维是一类新型磁性材料,应用十分广泛。本文对羰基铁热分解的有关热力学问题进行了理论分析,并从铁磁理论出发,探讨了利用羰基热分解磁场引导法制备几何尺寸可调的多晶铁纤维的可能。     

电磁感应型HDPE/TPI/铁纤维复合发热体材料的研究

以铁磁质材料为填料,HDPE/TPI为基体制备磁发热复合材料,研究了铁纤维直径、含量对材料电磁热效应的影响。讨论了铁纤维含量对材料导热性能和力学性能的影响。研究了不同含量铁纤维在基体中的分散状态对材料电磁热效应的影响,铁纤维直径为100-250μm,体积含量为9%时,材料具有较理想的综合性能。     

双金属-草酸配合物衍生铁酸镍及其吸附性能评价

本文采用热分解双金属-草酸配合物衍生制备铁酸镍多孔磁性纳米结构。通过改变加料顺序和溶剂组成实现对配合物生长的调节,并进一步获得具有不同尺寸、形貌和结构的多孔铁酸镍颗粒。表征结果显示利用该法制备的铁酸镍具有大的比表面积和较高的饱和磁化强度。染料吸附测试显示铁酸镍对刚果红具有良好的吸附性能,最佳样品的吸附容量可达212.1 mg·g~(-1),动力学拟合则表明可能主要以化学吸附为主。     

吸波多晶铁纤维制备工艺研究

介绍了吸波多晶铁纤维的制备装置和制备工艺,研究了反应温度、励磁电流、羰基铁流速及1次进样总量对多晶铁纤维的影响。通过实验,确定了多晶铁纤维的制备工艺为:反应温度400℃,励磁电流6A,羰基铁滴加速度1.0ml/min,1次进样总量为10ml。     

纳米铁酸镍锂的制备

我们发明了一种新型的纳米晶材料合成方法。以硝酸锂、硝酸镍、硝酸铁和草酸为原料,采用溶胶-凝胶法制备出了铁酸盐前驱体,通过高温煅烧得到了纳米晶铁氧体-铁酸镍锂,其颗料尺寸为纳米级(100 nm)。我们所合成的铁酸镍锂对RDX和AP的分解均有推进作用,降低了RDX和AP的热分解温度。     

铁纤维的常用制备方法及应用

从铁纤维的形成原理和制备与控制技术的角度出发，介绍了制备铁纤维的传统方法和还原法，模板法，磁场引导法等几种常用的化学方法，并简述了铁纤维在一般工业领域以及吸波和磁记录领域中的应用。     

水溶胶-凝胶法合成铌酸铁长纤维及其表征

采用一种简便的方法合成了单相铌酸铁长纤维.以自制Fe(OH)(HCOO)2和Nb2 O5·xH2O为原料,以水为溶剂,柠檬酸为金属离子螯合剂,过氧化氢为催化剂,制备了铌酸铁凝胶纤维;所制备的凝胶纤维和在不同温度热处理后所得铌酸铁无机纤维采用红外(FTIR)、热重(TG)、X-射线粉末衍射(XRD)、扫描电镜(SEM)等手段进行了表征.结果表明,所得纤维长度可达30 cm,直径3μm,XRD结果表明可在低于传统制备方法的温度下得到单斜钨锰铁矿型铌酸铁纤维.     

铁纤维的常用制备方法及应用

从铁纤维的形成原理和制备与控制技术的角度出发,介绍了制备铁纤维的传统方法和还原法、模板法、磁场引导法等几种常用的化学方法,并简述了铁纤维在一般工业领域以及吸波和磁记录领域中的应用。     

有机凝胶前驱体转化法制备CoFe_2O_4–BaTiO_3纳米复合纤维

铁磁–铁电复合纤维是一种新型功能陶瓷纤维材料,可潜在地用于磁、电能量转换。以柠檬酸和金属盐为原料,采用有机凝胶前驱体转化法制备了xCoFe2O4–(1–x)BaTiO3(x=0.2,0.3,0.4,0.5)纳米复合纤维。利用红外光谱、热重–差热分析、X射线衍射、扫描电子显微镜和振动样品磁强计等对纤维前驱体凝胶的结构、热分解过程及热处理产物组成、形貌和磁性能进行表征。研究表明:所制得的复合纤维直径细小、均匀、致密,最小直径达到1μm,长径比可达1×105。随着焙烧温度从900℃升高到1180℃,复合纤维中BaTiO3和CoFe2O4平均晶粒尺寸为20～70nm。xCoFe2O4–(1–x)BaTiO3纳米复合纤维的饱和磁化强度Ms与CoFe2O4在复合纤维中所占的摩尔分数x之间存在线性关系。     

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.     

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。     

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.     

基于ATRP法制备的触角状亲水性羟胺树脂的吸硼性能的研究

以大分子引发剂氯乙酰化聚苯乙烯微球(PS-acyl-Cl)经原子转移自由基聚合(ATRP)法引发丙烯酰胺(AM)和甲基丙烯酸缩水甘油酯(GMA)单体的共聚接枝,制得一种触角状亲水性环氧载体(PS-acyl-g-P(AM-co-GMA)),再经二乙醇胺(DEA)的环氧基开环胺化反应,得到一种含多个-NCH2CH2OH螯合配基的多齿-五元螯合环的触角状亲水性羟胺树脂(PS-acyl-g-P(AM-co-GMA)-DEA)。将此树脂用于硼吸附研究,结果表明,PS-acyl-g-P(AM-co-GMA)-DEA树脂对硼的吸附满足Langmuir方程,为单分子层吸附;饱和吸附量约为37.7 mg·g-1,且树脂5 min即可达到吸附平衡,与其它已报道的吸硼树脂相比,该树脂具有更高的吸附量和吸硼速率。吸附动力学研究表明,树脂吸附硼的过程主要由颗粒扩散过程控制。重复使用5次后该树脂的吸附量基本不变,解吸率均在90%以上,重复使用性能良好。