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以木薯淀粉为原料,3-氯-2-羟丙基三甲基氯化铵为阳离子醚化剂,自制碱性复合催化剂为醚化催化剂,双氧水为氧化剂,CuSO4为氧化催化剂,采用微波辅助一步法制备氧化阳离子淀粉。通过单因素实验研究醚化剂用量、碱性催化剂用量、氧化剂用量、CuSO4用量、反应温度和反应时间对粘度、取代度和反应效率的影响,并对工艺参数进行优化验证。结果表明,较佳的工艺条件为:淀粉用量200 g,醚化剂用量15 g,碱性催化剂与醚化剂摩尔比1.5,双氧水用量8 g,CuSO4用量0.09 g,反应温度90℃,反应时间18 min。在此条件下所得产品阳离子取代度(DS)为0.0414,醚化反应效率为92.87%,粘度为32.6 mPa·s(固含量12%,55℃)。本工艺制备的淀粉产品具有糊化温度低,糊液粘度低、稳定性高的特点。 相似文献
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以广西特产木薯淀粉为原料,硫酸铜(CuS04)为催化剂,双氧水(H2O2)为氧化剂,合成氧化淀粉。工艺采用正交试验法得到合成氧化淀粉的最佳工艺条件。考察了pH值、反应时间、反应温度、氧化剂和催化剂用量对氧化淀粉中羧基含量的影响。结果表明,当反应温度为45℃,反应时间为2.5h,pH值为7,氧化剂为20mL,催化剂为4m埘,氧化淀粉中的羧基含量(0.16%)最高。 相似文献
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以玉米淀粉为原料、以过氧化氢和过硫酸钾为复合氧化剂、以Fe2+为催化剂,在酸性条件下采用微波辅助复合氧化法合成氧化玉米淀粉。以反应温度、微波催化合成/萃取仪功率、催化剂质量分数(占干淀粉总量,下同)、复合氧化剂质量分数(占干淀粉总量,下同)、淀粉乳浓度、体系pH值、反应时间等因素为变量,以氧化度为衡量指标,采用单因素实验和正交实验确定微波辅助复合氧化法合成氧化玉米淀粉的最佳工艺条件为:反应温度55℃、微波催化合成/萃取仪功率400 W、催化剂质量分数0.3%、复合氧化剂质量分数8%、淀粉乳浓度45%、体系pH值4.00、反应时间21min,在此条件下,可以制得氧化度为0.140%的氧化玉米淀粉。 相似文献
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以钛硅分子筛为催化剂,以吡啶、双氧水为原料催化氧化合成 N-氧化吡啶。实验考察催化剂用量、吡啶与双氧水配比、反应温度、反应时间等对反应结果的影响。确定了较佳的工艺操作条件,即在TS-1分子筛催化剂作用下,催化剂与吡啶的质量比为1∶10,反应温度为80℃,吡啶与双氧水的摩尔比为1∶2,双氧水分多次滴加,反应时间为6 h。在此操作条件下,吡啶氧化转化率可达92%以上,N-氧化吡啶选择性可达97%。 相似文献
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J. R. Aldrich S. P. Carroll W. R. Lusby M. J. Thompson J. P. Kochansky R. M. Waters 《Journal of chemical ecology》1990,16(1):199-210
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. 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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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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2008~2009年世界塑料工业进展 总被引:4,自引:1,他引:3
中蓝晨光化工研究院有限公司《塑料工业》编辑部 《塑料工业》2010,38(3)
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。 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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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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