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以木薯淀粉、硅藻土、丙烯酸为原料,N,N’-亚甲基双丙烯酰胺为交联剂,过硫酸铵为引发剂,通过水溶液聚合法制备了木薯淀粉-硅藻土-丙烯酸复合高吸水树脂。分别对引发剂用量、交联剂用量、丙烯酸与淀粉的摩尔比、中和度、硅藻土用量进行单位因素实验和正交实验,并通过极差分析对影响材料吸水率的因素做统计分析。最佳的反应工艺条件为:以丙烯酸单体质量为基准,引发剂用量0.55%,交联剂用量0.06%,丙烯酸与淀粉摩尔比10.5,中和度75%,硅藻土用量18%。在此条件下合成的木薯淀粉-硅藻土-丙烯酸高吸水性树脂吸水、吸盐率分别为912 g/g,94 g/g。 相似文献
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采用水溶液聚合法,以改性淀粉和丙烯酸为原料,过硫酸钾为引发剂,N,N'-亚甲基双丙烯酰胺为交联剂,接枝共聚制备改性淀粉系高吸水树脂,并对其进行表面改性制备了具有抑菌性能的高吸水树脂。通过单因素试验和正交试验探究了改性淀粉种类、丙烯酸溶液的中和度、反应温度、引发剂和交联剂用量等因素对树脂吸水性能的影响;探讨了表面改性过程中苦参总碱添加量与抑菌效果间的关系。结果表明,以交联B3淀粉为原料,当淀粉用量为丙烯酸质量的15%,糊化温度为75℃,糊化时间为20 min,丙烯酸溶液的中和度为75%,引发剂用量为丙烯酸质量的0.3%,交联剂用量为丙烯酸质量的0.02%,70℃条件下反应4 h时,可制备吸水性能较好的高吸水树脂;当苦参总碱用量达到25.7 mg/g时即可使树脂在自然环境下具有较好的抑菌效果。最终制备的抑菌型改性淀粉系高吸水树脂的吸水倍率为715 g/g,接枝率为90%,在60℃条件下8 h的保水率约为7%。 相似文献
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采用紫外光引发聚合的方法制备淀粉-丙烯酸-丙烯酰胺高吸水性树脂,研究了淀粉用量、单体配比、丙烯酸中和度、交联剂、光引发剂等因素对吸水率的影响。当固化时间15min,淀粉用量10%(占丙烯酸用量的质量百分比).光引发剂用量0.4%,交联剂用量0.02%,中和度85%,丙烯陂/丙烯酰胺(摩尔比)10.可制得吸水率为985.1g/g的吸水树脂。 相似文献
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水溶液聚合小麦淀粉接枝丙烯酸高吸水性树脂的研究 总被引:1,自引:0,他引:1
以小麦淀粉与丙烯酸为原料,以N,N′-亚甲基双丙烯酰胺为交联剂,过硫酸铵为引发剂,采用水溶液聚合法合成高吸水性复合树脂。考察了丙烯酸的中和度、淀粉/单体比例、引发剂、交联剂等对聚合反应和树脂性能的影响。通过正交试验优选出物料的最佳配比:丙烯酸的中和度为90%,引发剂用量为0.5%,交联剂用量为0.05%,淀粉含量为10%。制备得到的吸水性复合树脂吸水率达1060g.g-1,性能优于聚丙烯酸钠高吸水性树脂。 相似文献
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以废弃蛋膜和丙烯酸为主要原料,以N,N'-亚甲基双丙烯酸胺为交联剂,过硫酸钾为引发剂,采用水溶液聚合法制备了改性蛋膜-聚丙烯酸高吸水性树脂。考察了聚合温度、引发剂和交联剂的用量以及改性蛋膜用量等各因素对树脂吸水倍率的影响。结果表明,聚合温度70℃,改性蛋膜用量为单体质量的10%,丙烯酸中和度为70%,引发剂用量为单体质量的0.1%,交联剂用量为单体质量的0.12%,树脂的吸水倍率可达667 g/g,在0.9%的NaCl溶液中吸盐水倍率达到106 g/g,其吸水速率较快。IR初步表明了蛋膜与丙烯酸的接枝聚合作用。 相似文献
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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. 相似文献
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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 总被引:15,自引:0,他引:15
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。 相似文献
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Cheng-Le Zhao Shane Porzio Alan Smith Haiyan Ge H. T. Davis L. E. Scriven 《Journal of Coatings Technology and Research》2006,3(2):109-115
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. 相似文献
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M. S. J. Simmonds W. M. Blaney F. Delle Monache M. Marquina Mac-Quhae G. B. Marini Bettolo 《Journal of chemical ecology》1985,11(12):1593-1599
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. 相似文献
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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. 相似文献
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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。 相似文献