基于高抗折强度的蒸压混凝土配合比优化

通过正交试验优化蒸压混凝土配合比，并以此配合比为依据研究纤维材料对蒸压混凝土抗折强度的影响。结果表明，纤维均有利于蒸压混凝土抗折强度的提高，但抗压强度提高幅度不明显。     

氧化石墨烯沙漠砂水泥基复合材料力学性能研究

通过正交试验,分析了氧化石墨烯(GO)掺量、沙漠砂替代率、水灰比和胶砂比对GO-沙漠砂水泥基复合材料28 d的抗压强度、抗折强度和稠度值的影响趋势.在正交试验基础上,进一步揭示沙漠砂替代率和GO掺量对复合材料7d、28 d抗压强度和抗折强度的影响规律.试验研究表明:随着GO掺量的增加,水泥基复合材料抗折和抗压强度先提高后降低,且对于抗压强度增强效果略超过抗折强度.当GO掺量为0.03wt％时,GO-沙漠砂砂浆试块抗压强度和抗折强度达到最大值;随着沙漠砂替代率增加,GO-沙漠砂砂浆试块抗折和抗压强度呈现先增大后减小趋势,沙漠砂替代率为50％时,氧化石墨烯沙漠砂砂浆试块抗压强度和抗折强度均达到最大值;但沙漠砂替代率为100％时,掺量为0.03wt％的GO-全沙漠沙水泥基材料强度提升最高,且28 d抗压、抗折强度可达标准砂试块强度.通过SEM对GO增强沙漠砂水泥基复合材料微观结构进行表征,发现GO能够优化水泥水化产物的微观结构形态,并且与沙漠砂活性材料产生正相关作用,从而形成更加致密均匀的结构改善沙漠砂水泥基复合材料的宏观性能.     

基于Design-expert的铁尾矿活性粉末混凝土配合比优化试验研究

针对铁尾矿活性粉末混凝土(RPC)原料控制因素繁多、配合比设计复杂的情况,为了制备达到RPC160级的混凝土,基于力学性能进行了配合比设计及优化研究.选取水胶比、胶集比、石英砂量、铁尾矿粒级、粉煤灰粉磨时间、硅灰掺量、钢纤维掺量等影响因素,并利用铁尾矿取代石英砂和粉煤灰取代硅灰,设置7因素4水平的正交试验,得到了RPC的抗压、抗折强度;运用软件Design-expert分析了强度试验结果,建立了响应曲面,拟合出响应曲面方程,并根据拟合方程优化了RPC的配合比.结果表明:以铁尾矿替代石英砂,粉煤灰取代硅灰可制备得到RPC160级混凝土;对抗压强度影响最大的两个因素是水胶比和铁尾矿粒级,对抗折强度影响最大的两个因素是钢纤维掺量和粉煤灰粉磨时间;提出了铁尾矿RPC抗压和抗折强度经验计算公式,根据设计强度指标优化了配比,给出了抗压强度≥170 MPa、抗折强度≥29 MPa的RPC各试验条件参数的范围,并通过验证试验证明了Design-expert软件优化结果的可靠性.     

石墨掺杂装配式结构水泥基复合材料的制备与性能研究

以石墨为掺料、水泥砂浆为基体材料制备了石墨掺杂装配式结构水泥基复合材料,考察了石墨掺量和石墨掺入方式对复合材料抗折强度、抗压强度和导热性能的影响.结果表明,无论是普通搅拌工艺试块还是超高速搅拌工艺试块,随着石墨掺量从0％增加至12％,试块的7 d抗折强度都呈现逐渐减小的趋势,试块的28 d抗折强度都呈现先增加后减小的特征;随着石墨掺量的增加,试块的7 d和28 d抗压强度都呈现逐渐减小的趋势.无论是普通搅拌工艺试块还是超高速搅拌工艺试块,随着石墨掺量从0％增加至12％,试块的28 d导热系数都呈现逐渐升高的趋势;石墨掺量为7％的石墨掺杂水泥基复合材料具有最佳的抗折强度、抗压强度与导热系数组合.     

大掺量粉煤灰混凝土配合比设计正交试验研究

采用正交试验方法对大掺量粉煤灰混凝土配合比进行试验研究,讨论了水泥品种,水胶比,胶凝材料用量和粉煤灰掺量对其28d强度的影响。结果表明,正交试验方法可以应用到大掺量粉煤灰配合比设计试验中;在4个因素中,粉煤灰掺量对混凝土强度的影响最大。     

掺粉煤灰水泥胶砂的正交试验研究

采用正交试验方法,研究了粉煤灰掺量、细度和Na2SO4掺量对水泥胶砂试块抗折、抗压强度影响规律。结果表明:粉煤灰掺量对水泥胶砂试块的7d抗折、抗压强度影响最显著;粉煤灰掺量和粉煤灰细度对28d抗折、抗压强度影响都比较显著;而Na2SO4掺量对7、28d抗折、抗压强度影响不大。     

基于正交试验的活性粉末混凝土力学性能及耐久性研究

通过正交试验设计了18组不同配合比的活性粉末混凝土(RPC),在常温养护制度下对其进行抗压强度和抗折强度试验研究,分析了砂胶比、水胶比、钢纤维掺量等因素对RPC力学性能的影响,考察了RPC破坏过程及形态.基于力学性能最优试验组,对该配合比进行优化,然后进行了抗冻融循环试验和抗硫酸盐侵蚀试验研究.试验结果表明:水胶比和钢纤维含量对RPC抗折和抗压强度影响显著,钢纤维含量过高导致RPC拌合物流动性较差,亦不经济,建议钢纤维体积含量控制在1.5％左右.RPC经冻融循环次数达150次时,其相对动弹模量为95.2％,质量损失忽略不计;经硫酸盐溶液侵泡的RPC试块强度相比在清水侵泡中提高了16.2％,RPC的抗硫酸盐侵蚀系数为116.5％.     

硅灰粉煤灰对喷射混凝土物理力学性能影响的试验研究

根据施工中喷射混凝土普遍存在早期强度低、后期强度不稳定、配合比简单等缺点,本文进行了硅灰、粉煤灰对喷射混凝土物理力学性能影响的试验研究。结果表明,硅灰可以提高喷射混凝土的早期强度,但会降低坍落度;而粉煤灰虽会降低早期强度,但经一段时间激活后可以提高后期强度。根据对正交试验结果的分析,确定了最优配合比,给出了各分项材料的最佳比例,可以满足一般工程需要。     

早强自密实PVA-ECC抗折性能试验研究

提出了一种早强自密实PVA-ECC(Polyvinyl Alcohol-Engineered Cementitious Composite)水泥基复合材料.通过正交试验的方法研究了水灰比、水泥与粉煤灰比和纤维体积掺量对于PVA-ECC流动性和抗折性能的影响,设计和优化了配合比.结果表明:纤维体积掺量对早强自密实PVA-ECC有着显著影响,当纤维掺量不超过0.5％时,纤维对于抗折强度没有明显影响;当纤维掺量超过0.5％时,抗折强度有着较大的提高.水灰比和水泥与粉煤灰比对早强自密实PVA-ECC有着一定影响,随着水灰比的降低,抗折强度有所提高;随着水泥与粉煤灰比的降低,抗折强度有所降低.     

PVA-ECC抗折强度与氯离子渗透性能试验研究

通过抗折强度试验与非稳态氯离子快速迁移方法对11组PVA-ECC试件进行研究,分析粉煤灰掺量及纤维掺量对PVA纤维水泥基复合材料抗折强度与氯离子渗透性能的影响.结果表明:试块抗折强度随粉煤灰掺量的增加而降低,随纤维掺量的增加而提高.当粉煤灰掺量为45％～50％、纤维掺量在1.5％～1.75％之间时,材料氯离子扩散系数最小.     

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.     

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.     

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。     

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。