纳米SiO2的制备及其原位改性

以天然优质粉石英自制的Na2O·3.1SiO2为原料、硅烷偶联剂KH-560、KH-570为改性剂、HCl为沉淀剂、聚乙二醇为表面活性剂,采用化学沉淀法制备了分散性好的改性纳米SiO2粉体.研究了硅烷偶联剂KH-560、KH-570对溶液中生成的二氧化硅粒子表面原位改性的影响及机理,优化了制备改性纳米SiO2粉体的工艺条件.利用扫描电镜(SEM)、红外光谱(FTIR)、热分析仪及粘度计对制备的产物进行了表征.结果表明硅烷偶联剂KH-560、KH-570都是有效的改性剂.     

纳米SiO_2表面化学改性研究

通过γ-(甲基丙烯酰氧)丙基三甲氧基硅烷与纳米SiO2表面的羟基发生化学反应,将KH-570化学键合在纳米SiO2表面,形成化学改性的纳米微粒MPS-SiO2。研究了硅烷偶联剂KH-570的用量、反应温度、反应时间、pH值、溶剂配比对纳米SiO2表面双键含量的影响,利用红外光谱、热失重对改性前、后的纳米SiO2进行了表征。结果表明,纳米SiO2表面成功地实现了化学改性。     

改性电石渣填充聚氯乙烯

利用挤塑辊压成型工艺制备电石渣/聚氯乙烯复合材料,探讨了不同偶联剂对于复合材料力学性能的影响,并对其中改性效果最好的偶联剂的最佳添加量和其改性的电石渣的最佳填充份数作了研究.结果表明:不同偶联剂中以硅烷偶联剂KH-590的改性效果最好,其最佳用量为2.0％.聚氯乙烯为100份时,KH-590改性的电石渣的最佳填充份数为60份.     

纳米锑掺杂氧化锡的表面改性

将纳米锑掺杂氧化锡(antimony doped tin oxide,ATO)分散于乙醇与水的混合改性介质中,利用硅烷偶联剂KH-570与纳米ATO表面羟基的脱水反应以及硅烷偶联剂间的缩合反应,制得了KH-570包覆的纳米ATO粉体。用FTIR、XPS、TG、TEM对纳米ATO粉体的表面结构进行了表征,并通过亲油性的测试,考察了其分散稳定性。结果表明,在ATO纳米粒子表面接枝上了7.36%～7.73%(质量分数)的KH-570,改性后的纳米ATO粒子的亲油性及分散性得到大幅度提高,改性ATO在正丁醇中能够稳定分散100 h以上。     

反应共混改性纳米二氧化硅/炭黑填充溶聚丁苯橡胶的结构与性能

采用动态反应共混法制备了含硫的硅烷偶联剂双-[γ-(三乙氧基硅)丙基]-四硫化物(Si-69)和双-[γ-(三乙氧基硅)丙基]-二硫化物(Si-75)改性纳米SiO2/炭黑填充溶聚丁苯橡胶(SSBR)硫化胶,分析了胶料的微观结构,研究了胶料的物理机械性能和动态力学性能等。结果表明,纳米填料在胶料中呈现较理想的分散状态;当纳米SiO2与炭黑填料的总量为70份时,随改性纳米SiO2用量的增加,SSBR硫化胶的邵尔A硬度、扯断伸长率、永久变形、撕裂强度下降,拉伸强度变化不大,300%定伸应力显著提高,生热明显下降,其中Si-75改性纳米SiO2/炭黑填充的SSBR综合性能更优;纳米填料在橡胶基体中的分散性好,胶料的动态生热低。     

纳米凹凸棒土填充丁苯橡胶的应用研究

通过采用熔融共混的方法,将硅烷偶联剂KH-550,KH-560,KH-570、A-151和硅-69改性过的AT与丁苯橡胶(SBR-1502)复合,制备出性能优异的AT/SBR混炼胶,并对其力学性能测试。研究结果表明,硅-69对AT的改性效果最好,当填充AT 30份时,AT/SBR纳米复合材料综合性能最好,其拉伸强度、撕裂强度、扯断伸长率分别达到13.33 MPa,44.51 MPa和518.8%。此外,鉴于AT与白炭黑同为无机填料,本论文还研究了AT与白炭黑并用对复合材料性能的影响。结果表明,当AT与白炭黑并用比为1:1(20份/20份)时,与填充40份白炭黑的丁苯橡胶的复合材料力学性能相当。因此,可考虑用AT与白炭黑并用,部分代替白炭黑,进而降低丁苯橡胶制品的成本。     

表面改性MCC对PLA复合材料力学与热稳定性能的影响

采用硅烷偶联剂(γ-甲基丙烯酰氧基丙基三甲氧基硅烷,KH-570)和纳米羟基磷灰石(n-HA)分别对微晶纤维素(MCC)表面处理.运用熔融共混方法制备改性微晶纤维素/聚乳酸(MCC/PLA)复合材料.研究了不同的MCC表面改性方法对MCC/PLA复合材料力学性能和热稳定性能的影响.结果表明:硅烷偶联剂KH-570化学包...     

不同硅烷偶联剂改性白炭黑对溶聚丁苯橡胶性能的影响

分别用4种硅烷偶联剂Si-69、KH-550、KH-570和KH-792对白炭黑进行改性,研究硅烷化白炭黑对溶聚丁苯橡胶硫化特性、物理机械性能、微观形态以及动态力学性能的影响。结果表明,加入硅烷偶联剂能够降低溶聚丁苯橡胶混炼胶的门尼黏度,明显提高硫化胶的物理机械性能,降低硫化胶的储能模量和损耗因子,使其Payne效应减弱; 其中用偶联剂Si-69改性白炭黑所填充溶聚丁苯橡胶的综合性能最佳,其次是KH-570。     

纳米锑掺杂氧化锡的表面改性研究

以乙醇与水的混合溶液作为改性介质,将纳米锑掺杂氧化锡(Antimony Doped Tin Oxide,ATO)分散于介质中,利用硅烷偶联剂KH-570与纳米ATO表面羟基的脱水反应以及硅烷偶联剂间的缩合反应,制得了KH-570包覆的纳米ATO粉体。通过FTIR、XPS、TG、TEM以及亲油性的测试对纳米ATO粉体的表面结构以及性能进行了表征,探讨了纳米ATO的与硅烷偶联剂的表面接枝情况以及硅烷偶联剂与纳米ATO在弱极性条件下的反应机理。研究结果表明：在ATO纳米粒子表面接枝上了一层约7.36-7.73wt%的KH570,改性后的纳米ATO粒子的亲油性能以及分散性得到大幅度的提高,改性ATO在正丁醇能够稳定分散100h以上。其根本原因在于改性后纳米ATO表面形成了一个网络结构硅烷偶联剂的包覆层,赋予纳米ATO粒子的表面良好的亲油性能以及分散性能。     

硅烷偶联剂KH-560改性纳米二氧化硅

用硅烷偶联剂KH-560对纳米SiO2样品表面进行接枝改性研究.考察了纳米SiO2的用量、KH-560百分含量、改性温度以及改性时间对改性效果的影响.采用红外光谱、热重分析手段对表面改性前后的纳米SiO2进行表征.纳米SiO2最佳工艺改性条件:纳米SiO2用量4％,KH-560百分含量2％,改性温度90℃C,改性时间6...     

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.     

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.     

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。