阻聚剂在C_5馏分热二聚过程中的应用

为减少C5馏分环戊二烯(CPD)热二聚过程中异戊二烯(IP)的聚合损失,采用封管实验方法考察了添加阻聚剂二乙基羟胺(DEHA)、对叔丁基邻苯二酚(TBC)、邻硝基苯酚(ONP)对热二聚过程中各二烯烃组分聚合程度的影响。结果表明,阻聚剂的加入不影响CPD的二聚,但减少了IP、间戊二烯(PD)的聚合损失。就阻聚效果而言,DEHA优于TBC和ONP。通过正交实验,考察了热二聚温度、时间以及DEHA质量分数等因素对双环戊二烯(DCPD)收率和IP聚合损失的影响。较佳工艺条件是热二聚温度120℃,反应时间3 h,DEHA质量分数500×10-6。该条件下DCPD的收率达到80%左右,IP的聚合损失可控制在8%以内。     

裂解C_5中异戊二烯阻聚工艺条件研究

在玻璃封管里比较了乙醇胺(C2H7NO)、硝基苯(C6H5NO2)、N-甲基吡咯烷酮(NMP)、邻硝基苯酚(ONP)、亚硝酸钠(NaNO2)对异戊二烯(IP)自由基聚合的阻聚效果,阻聚活性的次序为ONP>NaNO2>NMP>C6H5NO2>C2H7NO。并重点考察了反应温度、反应时间、加入量对ONP阻聚作用的影响。结果表明:温度越高,IP聚合速度越快。IP损失率与反应时间呈线性关系。阻聚效果较好的ONP的质量分数范围为0.3%—1.5%。     

二叔丁基氮氧自由基对AN_MA和MMA的高效阻聚作用

用混浊法和沸腾法分别研究了二叔丁基氮氧自由基(DTBNO)对丙烯腈(AN)及丙烯酸甲酯(MA)、甲基丙烯酸甲酯(MMA)自由基聚合的阻聚作用。结果表明,DTBNO对AN有较强的阻聚作用;DTBNO与对苯二酚(HQ)、苯醌(BQ)、二乙基羟胺(DEHA)等分别组成二元混合物时,其阻聚效果非常明显。当DTBNO-DEHA和DtBNO-HQ的浓度(ppm,下同)比分别为500:1000和1000:500时,对AN的阻聚效果最好;在二元混合阻聚剂中加入适量吩噻嗪(PT),其阻聚效果更佳,如DTBNO-DEHA-PT(500:500:500)在100℃时可使MMA完全终止聚合反应。     

N,N-二乙基羟胺对异戊二烯的阻聚作用

裂解C5馏分是裂解石油制乙烯过程中形成的副产物,从其中分离出异戊二烯（Ip）等双烯烃化合物是充分利用资源、提高裂解C5利用价值的有效途径。但是Ip等双烯烃化合物具有共轭双键,在热、氧和金属离子引发下相互作用,自聚或共聚成聚合物（胶质）,出现设备易挂胶的情况,给生产带来不便。因此在从C5馏分中分离Ip时,为防止其自聚或与烯烃类单体共聚,常在分离过程中加入阻聚剂。N,N-二乙基羟胺（DEHA）是一种高效阻聚剂。但是定量地分析时间、温度和DEHA含量对其阻聚效果的影响还未见报道。     

邻仲丁基4,6-二硝基苯酚(DNBP)对苯乙烯热聚合阻聚行为研究

用折光指数法考察了90~120℃下邻仲丁基4,6-二硝基苯酚(DNBP)对苯乙烯热聚合的阻聚效果,并从温度和质量浓度(0.02%~1%)两个方面进行研究。实验结果表明,随着温度的升高,阻聚效果逐渐变弱;随着阻聚剂浓度的增加,阻聚效果逐渐变强;温度对于阻聚过程的影响要强于浓度对其的影响;温度为120℃,DNBP浓度超过0.1%时,可以产生表面意义上的诱导期。     

双乙烯酮的阻聚研究

以醇类、对苯二酚、硫酸铜等为阻聚剂,考察其对双乙烯酮的阻聚作用,并研究了不同醇(甲醇、乙醇、乙二醇、正丁醇、异丙醇等)的阻聚效果。结果表明:醇类对双乙烯酮的阻聚作用较为明显,最优选择为乙二醇;以乙二醇作为阻聚剂加入双乙烯酮中进行蒸馏,可以提高双乙烯酮的收率;乙二醇本身不具有阻聚作用,其与原料中的乙酸酐发生酯化反应,生成的乙二醇二乙酸酯对双乙烯酮具有明显的阻聚效果。     

丁二烯产品中二聚物超标原因分析及预防措施

本文就丁二烯产品中二聚物超标的原因进行了分析 ,并提出预防措施。结果表明 ,TBC(对叔丁基邻苯二酚 )作为阻聚剂起到了很好的阻聚作用     

水解聚马来酸酐和聚丙烯酸阻磷酸钙垢性能及其机理研究

采用静态阻垢法研究在不同温度、不同阻垢剂浓度、不同pH及不同浓度的待测离子条件下水解聚马来酸酐(HPMA)和聚丙烯酸(PAA)阻磷酸钙垢的阻垢性能,并对其机理进行简单研究.结果表明:在相同条件下,HPMA阻磷酸钙垢的效果比PAA效果好.HPMA和PAA的阻垢率随着阻垢剂浓度的增加而升高,但是阻垢率并不是无限升高,在10 mg/L时,阻磷酸钙垢的阻垢率最大;温度较低时,HPMA的阻垢率率较大.并用量子化学方法中的半经验PM3方法研究了HPMA分子结构与其性能之间的关系,探讨了HPMA阻磷酸钙垢的阻垢机理,从微观角度解释了HPMA阻垢性能要优于PAA.     

钛酸丁酯/负载钛体系催化异戊二烯聚合

以钛酸丁酯[Ti(C_4H_9O)_4] 和TiCl_4/MgCl2(简称Ti)为主催化剂、三异丁基铝(简称Al)为助催化剂催化异戊二烯 (Ip)聚合,考察了Ti(C4H9O)4和Al用量对聚合物在汽油中可溶性及单体转化率、催化效率(CE)的影响,并对聚合物进行了表征.结果表明,当Ti/Ip(摩尔比)一定时,聚合物在汽油中的溶解度随着Ti(C_4H_9O)_4/Ip(摩尔比)的增加而增大,Ti(C_4H_9O)_4/Ip为3×10~(-3)时,单体转化率达到最大值;当主催化剂配比及用量一定时,聚合物在汽油中的溶解度随着Al/Ti(C_4H_9O)_4(摩尔比)的增加先增大后减小,当 Al/Ti(C_4H_9O)_4为10～15时,单体转化率和CE存在最大值;该催化体系制得的聚异戊二烯以反式-1,4-结构为主,同时包含一定量的3,4-和1,2-结构.     

温度和应变率对模内嵌膜片材力学性能的影响

通过单向拉伸试验研究了模内嵌膜工艺中常用的聚碳酸酯(PC)和聚甲基丙烯酸甲酯(PMMA)薄膜在不同温度和应变率下的力学性能。结果表明:随着温度的升高和应变率的降低,两种材料的屈服强度下降、断裂伸长率提高。当温度低于120℃时,PC薄膜的应变硬化系数(h)和图案变形度(r')对温度具有较弱的敏感性,而对应变率具有较强的敏感性,h和r'值随着应变率的增加而增大;当温度高于120℃时,PC薄膜的h和r'值则具有较弱的应变率敏感性和较强的温度敏感性,二者随着温度的升高而减小。由于PC薄膜的r'值远大于1而PMMA薄膜的r'值小于1,因此PMMA薄膜成型时的图案变形程度较PC薄膜轻。厚度对两款薄膜材料的屈服强度和h值无明显影响;但薄膜厚度会影响PC薄膜的r'值,薄膜越薄,r'值越小,但成型性能会变差。     

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。