DIN 磨耗半有效硫化体系的研究

通过对促进剂NS用量、硫磺用量和DTDM用量对天然橡胶DIN磨耗及其他物理机械性能的影响的研究,结果表明,在半有效硫磺硫化体系中,促进剂NS用量为1.4～1.6份,硫磺用量为1.8～2.0份, DTDM为0.6～0.8份时,天然橡胶具有好的耐DIN磨耗及好的物理机械性能。又利用正交实验,以确定硫磺、促进剂NS、DTDM及相互间交互作用对性能的影响,并通过直观分析和方差分析确定耐DIN磨耗的最优配方,促进剂NS用量为1.4份,硫磺用量为1.8份, DTDM为0.8份。     

半有效硫化体系对天然橡胶DIN磨耗量的影响

研究硫黄、促进剂NS和硫化剂DTDM用量对天然橡胶(NR)胶料性能的影响。在半有效硫化体系中,当硫黄用量为1.8~2份,促进剂NS用量为1.4~1.6份,硫化剂DTDM用量为0.6~0.8份时,NR硫化胶具有较好的物理性能和耐磨性能。利用正交试验法,确定硫黄、促进剂NS和硫化剂DTDM及其交互作用对NR胶料耐磨性能的影响,并通过直观分析和方差分析确定NR胶料DIN磨耗量最小的半有效硫化体系的配方为:硫黄1.8,硫化剂DTDM 0.8,促进剂NS1.4。     

NR/TPI并用胶半有效硫化体系的研究

考察了促进剂NS用量、硫黄用量和硫载体DTDM对NR/反式-1,4-聚异戊二烯(TPI)并用胶性能的影响.结果表明,在半有效硫化体系中,硫黄用量1.2～1.4份,促进剂NS用量1.4～1.6份时,NR/TPI(80/20)并用胶可以获得良好的综合性能.NR/TPI中使用DTDM后,硫化速度虽略有降低,但胶料焦烧时间延长,加工安全性提高,硫化胶物理机械性能、疲劳性能、滚动阻力以及耐老化性能均得到改善,这与DTDM在NR中的应用相似.     

促进剂NS对环氧化天然橡胶硫化特性与力学性能的影响

研究促进剂NS用量对环氧化程度为25的环氧化天然橡胶(ENR 25)的硫化特性、交联密度、力学性能及耐热空气老化性能的影响。研究结果表明,当硫磺用量一定时,ENR25的焦烧时间T10与正硫化时间T90随着促进剂NS用量的增加而延长,硫化速率指数Vc逐渐下降,MH-ML值逐渐增大;ENR25硫化胶的交联密度随着NS用量的增加而增大;当NS用量为1. 2phr,ENR25硫化胶的拉伸强度达到最佳值,随着促进剂NS用量的增加,ENR25硫化胶的撕裂强度逐渐增大;随着促进剂NS用量的增加,ENR25硫化胶的耐热空气老化性能提高。     

S型四辊压延机纠偏系统的改造

采用回归法分析了硫黄/DTDM并用比对硫化胶性能的影响。结果表明,合理的硫黄/DTDM并用比能赋予硫化胶较好的物理性能和抗热氧老化及抗疲劳性能。根据分析可以看出,硫化胶的定伸应力和交联密度与DTDM用量呈直线递增关系;拉伸强度和撕裂强度随DTDM 用量的增大有一峰值出现;采用促进剂NS,而且当硫黄/DTDM 并用比为0.6/2.4时,硫化胶综合性能最好。     

TMTD/DTDM对废旧轮胎胶粉再生效果的影响

将2种二硫化合物TMTD/DTDM并用,通过力化学法对废旧轮胎胎面胶粉进行了再生。结果表明,TMTD/DTDM用量为0.8份/0.2份时,再生效果比单用TMTD时有所改善;TMTD/DTDM用量为0.5份/0.5份时,再生胶有最佳物理机械性能。SEM结果表明,采用TMTD/DTDM并用且TMTD用量较多时,再生胶硫化胶具有较好界面结合。     

热空气老化对二烯类橡胶磨耗性能的影响规律研究

以丁苯橡胶（SBR）、顺丁橡胶（BR）和天然橡胶（NR）为研究对象,并以它们的基础配方为依据,研究了热空气老化对不同种类橡胶阿克隆磨耗和DIN磨耗性能的影响规律。研究结果表明,热空气老化对这3种橡胶的阿克隆和DIN磨耗性能的影响规律不同。对阿克隆磨耗性能来说,随老化时间的延长,丁苯橡胶和顺丁橡胶的耐磨性能提高,而天然橡胶的耐磨性随老化时间的延长而明显下降。对DIN磨耗性能来说,无论是丁苯橡胶、顺丁橡胶还是天然橡胶,它们的耐DIN磨耗性能都随着老化时间的延长而逐渐降低。防老剂的加入可以提高橡胶的耐阿克隆磨耗性能,但对DIN磨耗性能的影响却很小。     

硫化体系对胶料耐屈挠性能的影响

研究硫化体系对胶料(天然橡胶/顺丁橡胶并用胶为主体材料)耐屈挠性能的影响。结果表明:硫黄与促进剂用量比及促进剂品种均对胶料的各项性能产生影响;高促低硫硫化体系生成单硫键比例较大,胶料的耐屈挠性能较差;低促高硫硫化体系生成多硫键比例较大,胶料的耐屈挠性能提高;与促进剂TBBS相比,促进剂CBS,TiBTD和DTDM均对胶料的耐屈挠性能存在不利影响。     

硫磺用量对环氧化天然橡胶耐热空气老化性能的影响

研究硫磺用量对环氧化程度为25的环氧化天然橡胶(ENR25)的硫化特性、交联密度、力学性能、耐热空气老化性能及热氧稳定性的影响。研究结果表明,当促进剂NS用量一定时,随着硫磺的增加,ENR的焦烧硫化时间T_(10)和正硫化时间T_(90)逐渐缩短,硫化胶的力学性能显著提高,耐热空气老化性能逐渐降低,热稳定性也随之降低。     

TPI／IR并用胶的性能

考察了反式-1,4-聚异戊二烯（TPI）用量、3种典型促进剂次磺酰胺类CZ、噻唑类DM、秋兰姆类TMTD以及硫磺用量对TPI／异戊橡胶（IR）并用胶性能的影响。结果表明,以CZ为促进剂,当TPI的用量为15～25份,硫磺用量为1．7份时．并用胶可以获得良好的综合性能。同时,还比较了相同配方下的TPI／IR并用胶和天然橡胶（NR）的性能,发现除定伸应力和撕裂强度外,TPI／IR并用胶的其它性能均达到或优于NR硫化胶。     

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。