沙枣中总黄酮的提取工艺优选

优选沙枣中总黄酮的提取工艺条件,并通过还原力的测定初步研究黄酮的抗氧化活性。以总黄酮提取率为指标,采用单因素考察乙醇浓度、超声时间、料液比、超声功率对沙枣黄酮提取率的影响;在单因素试验的基础上,采用正交设计法优化沙枣中总黄酮的提取工艺条件。沙枣黄酮提取的最佳工艺条件:乙醇浓度60%、超声时间15 min、料液比1∶22(g/m L)、超声功率320 W,在此条件下,沙枣黄酮的提取率8.64%,影响沙枣黄酮提取率的因素从大到小依次为:料液比超声时间乙醇浓度超声功率;通过还原力的测定,表明沙枣总黄酮有较好的抗氧化活性。     

响应面法优化玫瑰总黄酮超声提取工艺

采用超声法提取苦水玫瑰总黄酮,选取液料比、乙醇体积分数和提取时间3个因子,应用Box-behnken响应面分析、优化工艺条件。结果表明,超声提取黄酮成分的最佳工艺条件为:乙醇体积分数46%,液料比36∶1,提取时间5.7 min。在该工艺条件下总黄酮提取率达9.42%。     

黄桷树叶中总黄酮的乙醇超声提取工艺研究

采用超声乙醇提取黄桷树叶中总黄酮,以芦丁为标准品,研究乙醇体积分数、料液比、提取时间、超声功率对提取率的影响。结果表明最优工艺组合为:超声功率420 W,料液比1∶50 g/mL,乙醇体积分数60%,超声提取20 min。最优工艺条件下,黄桷树叶中总黄酮提取率9.34%。     

黄桷树叶中总黄酮的乙醇超声提取工艺研究

采用超声乙醇提取黄桷树叶中总黄酮,以芦丁为标准品,研究乙醇体积分数、料液比、提取时间、超声功率对提取率的影响。结果表明最优工艺组合为:超声功率420 W,料液比1∶50 g/mL,乙醇体积分数60%,超声提取20 min。最优工艺条件下,黄桷树叶中总黄酮提取率9.34%。     

Box-Behnken响应面法优化藤梨根总黄酮超声提取工艺

目的:优化藤梨根总黄酮超声提取工艺。方法:超声提取药材,利用分光光度计法于510 nm波长处测定总黄酮含量,运用Design-Expert 8.0.6 Trial软件建立以总黄酮提取率作响应值,液料比、乙醇体积分数和提取时间为三因素的Box-Behnken响应面并进行多元二次回归分析。结果:最佳提取工艺条件为液料比12.45,乙醇体积分数78.09%,提取时间39.66 min,总黄酮的提取率为7.49%,与预测值7.58%偏差1.19%。结论:该工艺稳定可行,可用于藤梨根中总黄酮的工业化生产。     

草珊瑚总黄酮的超声提取工艺研究

研究了超声法提取草珊瑚总黄酮的工艺.影响草珊瑚总黄酮提取率的主要因素是乙醇体积分数,其次是提取次数,提取时间和液料比对提取率影响不显著.正交实验确定草珊瑚总黄酮的最佳超声提取条件是:40%乙醇,液料比10∶1,提取时间40 min,提取3次.此条件下总黄酮得率为8.53%.超声提取法具有短时高效的优点,适合于草珊瑚总黄酮的提取.     

响应面法优化提取藏红花中总黄酮的提取工艺

藏红花含有丰富的黄酮类化合物。本文采用超声提取工艺,以乙醇体积分数,超声时间,料液比作为优化因素,从藏红花粉中提取总黄酮,最后进行吸光度测定,并计算含量。其结果用Box-Behnken中心组合设计法处理,得到最适工艺条件:乙醇体积分数为75%,料液比12:1,超声提取时间为40min,总黄酮提取率为0.168%,相对偏差为0.04%。为进一步研究藏红花总黄酮提取工艺提供理论依据。     

超声波提取灯笼草中总黄酮的最佳提取条件的研究

本文以灯笼草为原料,研究超声波提取灯笼草总黄酮的最佳工艺。通过单因素试验研究乙醇体积分数、料液比、超声波功率及超声时间对总黄酮提取量的影响。以此为基础,采用正交试验设计,优化超声波提取灯笼草总黄酮工艺条件结果为乙醇浓度为60%,最佳料液比为1︰40,提取温度为50℃,超声波功率为100 W,提取时间30 min为最佳提取条件。黄酮提取率为5.66%。     

响应面法优化红薯叶多酚超声辅助提取工艺及其抗氧化活性研究

以红薯叶多酚提取率为评价指标,以提取温度、乙醇体积分数、料液比、提取时间为考察因素,在单因素实验的基础上,采用响应面法优化红薯叶多酚的超声辅助提取工艺,并通过测定红薯叶多酚对DPPH自由基、ABTS自由基的清除能力,评价其抗氧化活性.确定红薯叶多酚的最佳提取工艺为:提取温度61℃、乙醇体积分数72％、料液比1:21(g...     

正交实验法优选小蓟中总黄酮的提取工艺

优选小蓟中总黄酮的最佳提取工艺.以总黄酮提取率作为考察的指标,运用超声法提取小蓟中的总黄酮,将乙醇体积分数(A)、超声提取时间(B)和料液比(C)3个因素作为单因素实验对象,在单因素实验的基础上设计正交实验,从而确定最佳工艺为乙醇体积分数80％,超声提取时间45 min,料液比1:20(g·mL-1)时提取率最高.该方法操作简便、准确、提取率高,并且此实验结果为小蓟的进一步研究奠定了基础.     

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.     

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.     

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.     

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。