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采用超临界CO2萃取花生油脂中主要成分,研究了萃取压力、萃取温度、萃取时间和夹带剂用量等对萃取率的影响。结果表明,在CO2流量为10~12 L/h的前提下,最佳工艺条件是:萃取温度45℃,萃取压力30 MPa,萃取时间2.0 h,夹带剂用量20 mL。在此条件下,花生油脂的萃取率可达50.39%。影响提取率的主次因素为萃取压力萃取时间萃取温度夹带剂用量。 相似文献
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超临界CO2萃取β-胡萝卜素的工艺研究 总被引:1,自引:0,他引:1
对超临界CO2萃取胡萝卜中β-胡萝卜素的工艺进行了实验研究.用L9(34)正交实验研究了萃取压力、CO2流量、原料粒径、萃取温度等因素对萃取效果的影响,且对夹带剂的用量进行了研究与探讨.实验结果表明,4个因素中对提取率影响大小依次为压力>流量>粒径>温度,适宜的超临界萃取条件为萃取压力40 MPa,CO2流量10kg·h,原料粒径为40目,萃取温度40℃,此条件下的提取率为30.25×104.夹带剂可明显提高萃取率,适宜的夹带剂添加量为40 mL.此外还将超临界萃取与有机溶剂提取进行了比较,效果均优于有机溶剂. 相似文献
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超临界CO2流体萃取大黄游离蒽醌的研究 总被引:10,自引:0,他引:10
研究了带夹带剂的超临界流体萃取大黄中的五种有效蒽醌类物质(大黄酚、大黄素、芦荟大黄素、大黄酸和大黄素甲醚)的工艺,考察了萃取条件(温度和压力)、CO2流量、萃取时间、夹带剂种类等对大黄游离蒽醌萃取率的影响.通过正交实验对萃取釜条件(萃取压力、温度和夹带剂用量)进行了优化;采用液相色谱对萃取产物进行了分析.结果表明,分离釜的温度和压力、CO2流量等对萃取效率影响较小;最佳工艺条件为静萃取时间为60 min、动萃取时间为30 min、以乙醇作夹带剂、乙醇用量300 mL·(100g大黄)-1、萃取温度45℃、萃取压力45 MPa.在此条件下大黄游离蒽醌的萃取量达1.15%. 相似文献
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用正交实验法优化采用超临界CO2技术萃取车前草中熊果酸的工艺条件。在单因素实验基础上,采取L9(3^3)探讨萃取压力、萃取温度、CO2流量对萃取车前草熊果酸的得率的影响情况,确定了超临界CO2萃取车前草中熊果酸的适宜条件。超临界萃取最优条件为:萃取压力35MPa,萃取温度为40℃,选择无水乙醇为夹带剂,夹带剂质量分数为20%,萃取时间2h,CO2流量为20L/h,产品的出膏率为3.58%,萃取物中熊果酸的含量为6.93%。该法与传统方法相比,具有操作简便快速,溶剂用量少,有效成分提取率高等优点。 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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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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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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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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