紫花地丁黄酮体外抗氧化实验

运用溶剂提取法提取紫花地丁黄酮类成分,采用DPPH法和水杨酸清除自由基法测定紫花地丁黄酮体外抗氧化活性。研究发现,黄酮的IC_(50)为0.4632 mg/m L,抗坏血酸IC_(50)的为0.977 mg/m L,紫花地丁总黄酮抗氧化能力与其质量浓度均呈正相关性比例,即随质量浓度的增大其抗氧化能力也增大。结果表明,清除率与浓度存在明显的量效关系,随着质量浓度增大,总抗氧化能力也增加。     

饿蚂蝗中黄酮类化合物的抗氧化活性的研究

提取了饿蚂蝗中的黄酮化合物,并研究了其含量及与体外抗氧化活性关系。用体积分数为75%的乙醇提取饿蚂蝗全草黄酮化合物,并采用HPD-100大孔树脂对粗提液进行精制,利用NaNO2-Al（ NO3）3-NaOH显色法和可见分光光度法测定精制黄酮的含量。采用DPPH和ABTS自由基测定法,对饿蚂蝗黄酮化合物的抗氧化活性进行评价。结果表明：在自由基清除实验中,精制饿蚂蝗黄酮类化合物自由基清除能力高于未精制的乙醇提取物。饿蚂蝗黄酮类化合物的体外抗氧化活性与黄酮含量呈正相关性。     

石上柏中双黄酮对DPPH自由基的清除作用研究

研究石上柏中双黄酮类化合物的抗氧化活性。采用乙醇回流提取,聚酰胺柱色谱和葡聚糖凝胶柱色谱纯化得到双黄酮类混合物结晶,利用液质联用法鉴定组成。采用DPPH自由基清除法测试其抗氧化活性,以抗坏血酸作为阳性对照。获得的石上柏双黄酮类混合物结晶由穗花杉双黄酮,罗波斯塔双黄酮,7-去甲基银杏双黄酮,罗波斯塔-4'-甲醚,罗汉松双黄酮A组成,在质量浓度52.3μg/mL时,总双黄酮对DPPH自由基的清除率为8.0%,而抗坏血酸为95.5%。石上柏中双黄酮类对DPPH自由基有一定的清除作用,相对于抗坏血酸较弱。     

银杏叶总黄酮的提取及其抗氧化性的研究

采取微波辅助乙醇法提取银杏叶总黄酮,探讨最佳提取条件及产品的抗氧化性活性。研究表明,提取的影响因素顺序为乙醇浓度>固液比>微波时间>微波功率,最佳工艺条件为:乙醇浓度90%,固液比1∶40(g/mL),微波时间20 min,微波功率600 W。抗氧化的实验表明,银杏叶黄酮提取物对超氧阴离子、羟自由基和DPPH自由基均有较强的清除作用,且随着添加量的增大而增强。同浓度的银杏提取物比同浓度的Vc溶液清除效果好。     

糙米黄酮的提取及其抗氧化作用的研究

本实验采用乙醇浸提法提取糙米黄酮。首先考察溶剂浓度、料液比、提取温度、提取时间等因素对提取率的影响。在单因素试验的基础上,根据正交试验设计原理,采用极差分析法,对提取条件进行优化。确定糙米黄酮的最佳提取工艺条件为:提取温度60℃,提取时间6 h,料液比为1∶40,乙醇浓度为60%,在此条件下糙米黄酮的提取量为0.556 mg/g。最后,以邻二氮菲-亚铁化学法测定其抗氧化作用。和VC对比,考察糙米黄酮对羟自由基(·OH)的清除能力,结果表明糙米黄酮对羟自由基(·OH)具有较强的清除能力,且在同质量浓度下,糙米黄酮对羟自由基(·OH)的清除能力大于VC对羟自由基的清除能力。     

弯萼金丝桃总黄酮提取及抗氧化、降糖活性

摘要：为获得弯萼金丝桃总黄酮（TF）最佳提取工艺及抗氧化活性、降糖活性,探究5种提取工艺(超声辅助提取、酸解提取、酶解提取、热水提取、热醇提取) 对TF提取量的影响,通过单因素和响应面实验优化提取工艺。采用高效液相色谱(HPLC)测定并分析7种主要黄酮苷元的分布及含量,并进一步研究TF与体外抗氧化活性（DPPH?清除能力、ABTS自由基清除能力、羟基自由基清除能力、还原能力）的相关性及对α-葡萄糖苷酶的体外降糖能力。结果表明,超声辅助提取TF提取量最高。响应面优化最佳提取工艺为：温度68 ℃,时间23 min、乙醇体积分数24 %、液料比63:1 mL/g,在该条件下,TF提取量为34.85 mg RT/g（以每克弯萼金丝桃中黄酮类化合物相当于芦丁RT质量表示）;高效液相色谱法分别鉴定出TF中7种主要黄酮类化合物,其中TF中含量最高的黄酮化合物为槲皮素-3-O-洋槐糖-7-0-鼠李糖苷、槲皮素,分别为3.897 mg/g、2.874 mg/g;TF质量浓度与DPPH?清除能力、ABTS自由基清除能力、羟基自由基清除能力、还原能力呈显著正相关,对α-葡萄糖苷酶的降糖能力可达到92.6 %。     

超声醇提黄花蒿残渣总黄酮的工艺优化及抗氧化活性

以提取青蒿素后黄花蒿残渣为原料,采用超声醇提总黄酮。通过单因素实验方法和正交实验方法确定了最佳提取工艺条件;考察所得黄酮纯化物对羟基自由基的清除能力,与抗坏血酸、柠檬酸对比测定其对油脂的抗氧化性能。结果表明,黄花蒿残渣中总黄酮超声辅助提取的最佳提取工艺为:按料液比1∶30(即每克固体物料加入30 mL液体物料,下同)加入体积分数50%的乙醇,在55℃下用200 W超声辅助提取40 min,黄花蒿残渣中总黄酮提取率可达到9.10%。该黄酮纯化物对羟基自由基具有清除能力,随质量浓度的增大而升高;黄酮纯化物对油脂有明显的抗氧化性作用,对植物油的抗氧化能力强于抗坏血酸和柠檬酸,对动物油脂的抗氧化能力稍弱于抗坏血酸而略强于柠檬酸。     

小叶榕榕树须总黄酮提取及对羟自由基清除研究

采用乙醇提取法从小叶榕榕树须中提取黄酮类物质,对所提取的黄酮类物质进行了验证,并用紫外分光光度法测定其含量。测得样品中总黄酮的质量浓度为1.151mg/mL,回收率为99.36%,纯度和产率均较高。测定了该提取液对Fenton体系产生的羟自由基的清除作用,结果表明,提取液含量的增加,对羟自由基的清除能力也增强。     

银杏叶、乌饭树叶和桑叶提取物的抗氧化性比较

用70乙醇和水分别浸提银杏叶、乌饭树叶和桑叶中的粗黄酮,测定提取物对DPPH自由基的清除能力。结果表明,醇提物和水提物的DPPH自由基清除能力均随料液比的提高而增大。醇提物的DPPH自由基清除能力大小依次为:银杏叶乌饭树叶桑叶,水提物的DPPH自由基清除能力大小依次为:乌饭树叶桑叶银杏叶。     

地肤子黄酮类提取物的抗氧化活性研究

研究了地肤子（Kochiascopana）中黄酮类化合物的提取及其抗氧化活性作用。通过对索氏提取方法来提取地肤子中的黄酮类化合物,确立了地肤子黄酮类化合物最佳提取工艺方案。研究结果表明：最佳提取条件是：提取试剂为75％乙醇,固液比为1：10,提取时间4h,提取温度55℃,提取液中黄酮类化合物产率为8．95％。所得到的地肤子黄酮类化合物在一定浓度范围内具有较强的清除自由基和抗氧化能力,这为地肤子黄酮类化合物的开发提供参考。     

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.     

Methyl 2,4,6-decatrienoates Attract Stink Bugs and Tachinid Parasitoids

Halyomorpha halys (Stål) (Pentatomidae), called the brown marmorated stink bug (BMSB), is a newly invasive species in the eastern USA that is rapidly spreading from the original point of establishment in Allentown, PA. In its native range, the BMSB is reportedly attracted to methyl (E,E,Z)-2,4,6-decatrienoate, the male-produced pheromone of another pentatomid common in eastern Asia, Plautia stali Scott. In North America, Thyanta spp. are the only pentatomids known to produce methyl 2,4,6-decatrienoate [the (E,Z,Z)-isomer] as part of their pheromones. Methyl 2,4,6-decatrienoates were field-tested in Maryland to monitor the spread of the BMSB and to explore the possibility that Thyanta spp. are an alternate host for parasitic tachinid flies that use stink bug pheromones as host-finding kairomones. Here we report the first captures of adult and nymph BMSBs in traps baited with methyl (E,E,Z)-2,4,6-decatrienoate in central Maryland and present data verifying that the tachinid, Euclytia flava (Townsend), exploits methyl (E,Z,Z)-2,4,6-decatrienoate as a kairomone. We also report the unexpected finding that various isomers of methyl 2,4,6-decatrienoate attract Acrosternum hilare (Say), although this bug apparently does not produce methyl decatrienoates. Other stink bugs and tachinids native to North America were also attracted to methyl 2,4,6-decatrienoates. These data indicate there are Heteroptera in North America in addition to Thyanta spp. that probably use methyl 2,4,6-decatrienoates as pheromones. The evidence that some pentatomids exploit the pheromones of other true bugs as kairomones to find food or to congregate as a passive defense against tachinid parasitism is discussed.     

2007～2008年世界塑料工业进展

收集了2007年7月～2008年6月世界塑料工业的相关资料,介绍了2007～2008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、不饱和聚酯树脂、环氧树脂)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.     

2005～2006年国外塑料工业进展

收集了2005年7月～2006年6月国外塑料工业的相关资料,介绍了2005—2006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生产量以及各国塑料制品的进出口情况。作为对比,介绍了中国塑料的生产情况。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（聚酰胺、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚）、通用热固性树脂（酚醛、聚氨酯、不饱和树脂、环氧树脂）、特种工程塑料（聚苯硫醚、液晶聚合物、聚醚醚酮）的品种顺序,对树脂的产量、消费量、供需状况及合成工艺、产品开发、树脂品种的延伸及应用的扩展作了详细的介绍。