吐温-20对PB-g-PS胶乳改性水泥砂浆的性能影响

通过半连续胶乳接枝聚合反应合成了m(聚丁二烯)/m(苯乙烯)比例为50/50的聚丁二烯接枝聚苯乙烯(St)共聚胶乳(PB-g-PS).并向胶乳中加入了占固体质量为3％、5％和7％的吐温-20,制备三种水泥改性剂.水灰比为0.5(质量比),将三种水泥改性剂用于制备胶乳改性水泥砂浆,考察了吐温-20含量和聚灰比对改性砂浆的流动度、抗压和抗折强度、以及水吸收速率的影响.研究表明:在一定掺量范围内,改性砂浆的流动度随吐温-20含量和聚灰比的增加而增加;三种水泥改性剂均能够显著降低改性砂浆的吸水率;合适的水泥改性剂和吐温-20掺量,可使砂浆的力学性能损失较少;利用SEM进行了微观形貌分析,观察到了桥接结构、互穿网络结构以及孔洞结构,这些结构上的变化均有利于改善砂浆的性能;并对吐温-20的作用机理进行了分析,认为是水分子层的隔离作用.综上,吐温-20可以作为PB-g-PS胶乳的稳定剂.     

聚丁二烯接枝聚苯乙烯和甲基丙烯酸环氧丙酯共聚胶乳的制备及其对水泥水化的影响

以聚丁二烯(PB)、苯乙烯、甲基丙烯酸环氧丙酯(GMA)为原料,采用半连续乳液接枝共聚法合成了PB接枝聚苯乙烯和GMA共聚胶乳,并用其改性水泥砂浆,通过傅里叶变换红外光谱和差示扫描量热法考察了胶乳对水泥水化作用的影响。结果表明,随着GMA含量的增加,胶乳的酯羰基吸收峰变强,说明GMA已经接枝到PB主链上;聚灰比的增加促进了水泥水化作用,Ca(OH)2分解吸热峰向低温方向偏移约40℃;随着GMA含量的增加,水化产物中Ca(OH)2含量呈现减少的趋势,Ca(OH)2分解吸热峰并未向低温方向偏移。     

聚丁二烯接枝聚苯乙烯胶乳改性水泥砂浆的耐硫酸腐蚀性能

通过半连续乳液接枝共聚的方法制备了聚丁二烯(PB)与聚苯乙烯(PS)质量比为50/50的聚丁二烯接枝聚苯乙烯(PB-g-PS)共聚胶乳.在水与水泥的质量比为0.40、胶乳固体质量与水泥的质量比为10％的条件下,将PB-g-PS胶乳掺入水泥砂浆对其进行改性,并通过扫描电镜观察了参比及改性砂浆的微观形貌.经研究发现,当稀硫酸质量浓度增加及浸泡时间延长时,参比水泥砂浆的失重率及吸水率也随之增加,抗压强度变小,但改性水泥砂浆耐稀硫酸腐蚀性明显优于参比水泥砂浆;参比及改性水泥砂浆在质量浓度为15％的稀硫酸溶液中浸泡100 d时,失重率前者几乎达100％而后者为68.65％,且改性水泥砂浆的抗压强度降幅较小;参比及改性水泥砂浆在质量浓度为10％的稀硫酸溶液中浸泡100 d时,吸水率分别为7.19％和4.09％;改性砂浆的结构更致密且界面结构得到了改善,随稀硫酸溶液浓度的增加,氢氧化钙晶体数量减少,形态呈六角形片状结构.     

PB-g-PS胶乳的制备及其改性水泥砂浆

采用种子乳液聚合法制备了聚丁二烯接枝聚苯乙烯(PB-g-PS)核壳结构胶乳,聚丁二烯与聚苯乙烯的质量比为70/30、50/50和30/70,并将3种胶乳用于改性水泥砂浆。在固定水灰质量比为0.5,温度为20℃、相对湿度(RH)为90%的标准养护箱中养护24h后脱模,在混合养护条件下(20℃水中养护5d,再于20℃相对湿度为65%的空气中养护21d,共养护28d),考察了聚灰比(聚合物与水泥质量比)和核壳比(聚丁二烯与聚苯乙烯质量比)对胶乳改性水泥砂浆的流动度、抗压和抗折强度以及水吸收速率的影响。结果表明,在一定掺量范围内,改性砂浆的流动度随聚灰比的增加而增加,随核壳比的增加而降低;能显著降低改性砂浆的毛细孔吸水率;聚合物的加入对砂浆的力学性能产生重要影响,总体使抗压强度降低,部分改性砂浆的抗折强度降低较少。利用扫描电镜(SEM)考察了胶乳改性砂浆(LMMs)的形态结构,微观结构分析表明,改性砂浆的结构更加致密,胶乳在砂浆中可以形成聚合物膜,孔洞被氢氧化钙晶体和聚合物膜封闭,另外,聚合物膜和水泥基体已形成双连续的互穿网络结构,这些结构上的变化改善了砂浆性能。     

硅灰对HPMC改性水泥砂浆性能的影响

研究硅灰对羟丙基甲基纤维素(HPMC)改性水泥砂浆的工作性能、力学性能及孔结构的影响。结果表明:(1)当硅灰掺量2%时,流动度和稠度相对基准组略有提高。当硅灰掺量为4%~10%时,新拌水泥砂浆的流动度和稠度呈现递减的趋势,且硅灰最大掺量10%时,流动度和稠度明显降低并出现空洞。(2)硅灰对HPMC改性水泥砂浆3 d龄期的抗折和抗压强度影响不大,但能显著提高28 d龄期的抗折和抗压强度;当硅灰掺量为8%和10%时,28 d龄期试件的抗折强度提高了19%,抗压强度提高了40%。(3)随着硅灰掺量的增加,HPMC改性水泥砂浆新拌砂浆表面气泡不断减少,28 d龄期试样断面的孔结构不断优化。硅灰掺量为8%和10%时,新拌浆体表面气泡最少,试样断面孔结构达到最佳状态。     

聚丁二烯-g-聚苯乙烯和聚甲基丙烯酸环氧丙酯胶乳改性水泥砂浆的耐腐蚀性能

通过半连续乳液接枝共聚法合成了聚丁二烯（PB）/聚苯乙烯/聚甲基丙烯酸环氧丙酯（质量比）为50/46/4的PB-g-接枝聚苯乙烯和聚甲基丙烯酸环氧丙酯（PSG）胶乳,在水灰比为0.4（质量比）、聚灰比为0.1（质量比）的条件下用其改性水泥砂浆,考察了硫酸溶液的质量分数和浸入时间对PB-g-PSG胶乳改性水泥砂浆耐腐蚀性能的影响。结果表明,随着硫酸溶液质量分数的增大和浸入时间的延长,水泥砂浆的质量损失及吸水率增大,抗压强度降低,但改性水泥砂浆的耐腐蚀性能比参比水泥砂浆显著提高。参比水泥砂浆在质量分数为15%的硫酸溶液中浸入100 d后几乎被完全侵蚀,而改性水泥砂浆的质量损失率仅为69.23%;参比水泥砂浆在质量分数为10%的硫酸溶液中浸入100 d后吸水率为7.19%,而改性水泥砂浆在质量分数为10%和15%硫酸溶液中浸入100 d后其吸水率分别为3.97%和5.24%;改性水泥砂浆的抗压强度降低幅度也比参比水泥砂浆显著减小。     

硅灰掺量对海工水泥混凝土耐久性能的影响

以粉煤灰、矿粉为混合材与硅酸盐水泥熟料、石膏复合,通过内掺硅灰制备海工水泥,研究硅灰掺量对海工水泥物理性能和混凝土耐久性能的影响。试验结果表明,掺入硅灰能明显增加海工水泥的标准稠度用水量,延长凝结时间,且与硅灰掺量呈正相关;当硅灰掺量≤4%时,水泥砂浆的抗压强度和抗折强度均随硅灰掺量的增加而增大,耐久性也逐渐提高;当硅灰掺量4%时,其强度和耐久性能的增加效果并不明显。颗粒分析结果表明,所制备海工水泥在0~30μm粒径范围内的比例高于普通硅酸盐水泥,颗粒分布更合理。XRD分析结果表明,适宜的硅灰掺量(4%)能充分发挥其火山灰效应和物理填充作用,提高水泥石的致密度。     

硅灰掺量对免烧粉煤灰陶粒性能的影响

以粉煤灰为原料,辅掺硅灰制备了碱激发免烧陶粒。采用筒压强度试验、吸水率试验、含泥量试验、磨破率试验、耐腐蚀试验、X射线衍射仪和扫描电子显微镜试验,系统地研究了硅灰掺量对陶粒性能的影响。结果表明,3 d、7 d、14 d龄期时,随着硅灰掺量增加,粉煤灰陶粒的筒压强度呈逐渐增加趋势,磨破率与吸水率呈逐渐下降趋势,耐腐蚀性能也得到提高。当硅灰掺量为15%和20%(质量分数)时,龄期为14 d时,陶粒的筒压强度分别达到19.43 MPa和20.37 MPa。由微观分析知,适量的硅灰掺量可以提高粉煤灰的水化程度,增加陶粒结构密实性,但当掺量达到15%~20%时,水化程度有所减弱。     

NaOH激发矿渣砂浆强度和抗氯离子渗透性能的研究

NaOH激发矿渣砂浆(简称NAS砂浆)和水泥砂浆的强度和抗氯离子渗透性能用NaCl溶液浸泡法研究.保持矿渣数量和水胶比不变,当NaOH数量从2％增加到6％时,NAS砂浆强度先增加后降低,抗氯离子渗透性能随NaOH含量增加而增加,且显著强于同抗压强度的水泥砂浆.在NAS砂浆中掺入水泥取代部分矿渣和NaOH后,砂浆的强度会降低,且水泥掺量越多,砂浆强度降低越多;当水泥掺量为5％～15％时砂浆抗氯离子渗透性能不会降低反而稍有增加,但当水泥掺量为20％时,砂浆抗氯离子渗透性能明显下降;水泥掺量为5％～20％的NAS砂浆抗氯离子渗透性能显著强于同抗压强度的水泥砂浆.用粉煤灰取代NAS砂浆中部分矿渣和NaOH后,砂浆强度会降低,当粉煤灰掺量为10％～ 30％时,砂浆强度降低幅度较小,但当粉煤灰掺量为40％,则砂浆强度会显著降低;当粉煤灰掺量为10％ ～40％时,砂浆抗氯离子渗透性能降低,但显著强于同抗压强度的水泥砂浆.     

橡胶粉、稻壳灰/硅灰改性铁路工程用的水泥砂浆试验

针对传统铁路工程用的水泥砂浆抗冻融性和抗渗透性差的问题,提出用稻壳灰替代一部分硅灰,用橡胶粉替代一部分水泥对砂浆进行改性。以水泥砂浆性能为指标,对水泥砂浆的配比进行设计。结果表明：当橡胶粉替代水泥量为8%,稻壳灰掺量为100%时,28 d水泥基体抗压抗折强度下降了34.5%,质量损失率降低了28.5%,相对动弹性模量降低了21.8%。     

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.     

Sapindaceae,cyanolipids, and bugs

Scentless plant bugs (Heteroptera: Rhopalidae) are so named because adults of the Serinethinae have vestigial metathoracic scent glands. Serinethines are seed predators of Sapindales, especially Sapindaceae that produce toxic cyanolipids. In two serinethine species whose ranges extend into the southern United States,Jadera haematoloma andJ. sanguinolenta, sequestration of host cyanolipids as glucosides renders these gregarious, aposematic insects unpalatable to a variety of predators. The blood glucoside profile and cyanogenesis ofJadera varies depending on the cyanolipid chemistry of hosts, and adults and larvae fed golden rain tree seeds (Koelreuteria paniculata) excrete the volatile lactone, 4-methyl-2(5H)-furanone, to which they are attracted.Jadera fed balloon vine seeds (Cardiospermum spp.) do not excrete the attractive lactone. Loss of the usual heteropteran defensive glands in serinethines may have coevolved with host specificity on toxic plants, and the orientation ofJadera to a volatile excretory product could be an adaptive response to save time.Mention of a commercial product does not consititute an endorsement by the USDA.     

2008～2009年世界塑料工业进展

收集了2008年7月～2009年6月世界塑料工业的相关资料,介绍了2008～2009年国外塑料工业的发展情况,提供了世界塑料产量、消费量及全球各类树脂的需求量及产能情况。按通用热塑性树脂(聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂)、工程塑料(尼龙、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚)、特种工程塑料(聚苯硫醚、液晶聚合物、聚醚醚酮)、通用热固性树脂(酚醛、聚氨酯、环氧树脂、不饱和聚酯树脂)不同品种的顺序,对树脂的产量、消费量、供需状况及合成工艺、产品应用开发、树脂品种的延伸及应用的进一步扩展等技术作了详细介绍。     

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。     

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.