苯酚-硫酸显色法测定多糖

芦荟多糖是芦荟的主要生物活性组分,其含量是芦荟制品的重要理化检验指标之一。文章研究了测定芦荟中多糖含量的测定方法。用紫外可见分光计,经苯酚-硫酸显色,对多糖进行测定。该法测定芦荟多糖含量,简单、快速、灵敏,而且结果满意。     

膜分离技术在芦荟原汁加工中的应用

利用膜分离技术将芦荟原汁分成三部分：芦荟水、芦荟苷浓缩液、芦荟多糖浓缩液。芦荟水可作饮料：芦荟苷浓缩液作药用原料;芦荟多糖浓缩液作食品、化妆品添加剂。     

芦荟多糖的微波辅助提取及其保湿性能研究

通过微波提取技术从芦荟中提取芦荟多糖,采用单因素和正交试验,分别考察了微波辐射功率、时间、料液比、温度等因素对芦荟多糖提取率的影响。结果表明:微波时间为5 min,微波功率600 W,料液比1∶6 g/m L,温度为50℃时,提取工艺最佳,提取率为0.231 7%。通过干燥器控制湿度的方法对芦荟多糖提取物进行吸湿和保湿性能测试,结果表明芦荟多糖提取物是良好的保湿剂。     

芦荟多糖的含量测定

芦荟具有很高的药用价值 ,品种极多。我们从中华芦荟中利用热水浸提法分离提取出了水溶性的多糖 ,并应用紫外可见分光光度法对多糖含量进行了测定 ,经苯酚 -硫酸显色 ,于 489nm处测定 ,其中的多糖含量为 7.6 9%,该法测定芦荟多糖含量 ,简单、快速、灵敏 ,而且结果稳定。     

微波法提取木立芦荟多糖的工艺研究

采用微波法提取木立芦荟多糖．通过正交实验确定最佳提取条件为：微波功率420W、微波时间3min、浸提温度70℃、料液比1：30（g：mL）,在此条件下,木立芦荟多糖的提取率达到6．05％,比热水浸提法高出35．8％。     

星点设计-响应面法优化芦荟多糖超声波提取工艺以及其抗氧化活性研究

试验采用星点设计法优化芦荟多糖超声提取工艺,以芦荟多糖对二苯代苦味酸(DPPH)自由基的清除作用评价其抗氧化活性。结果表明:最佳提取工艺是温度为43℃,时间为41 min,功率为72%,液料比为60:1,芦荟多糖的提取率为11.9%。芦荟多糖对DPPH自由基有较强的清除作用,并与多糖质量浓度呈一定的量效关系。说明芦荟多糖较好的抗氧化活性,作为一种天然的抗氧化剂具有较好的应用前景。     

芦荟多糖对小鼠抗肿瘤作用的实验研究

目的研究中华芦荟多糖(AP)对小鼠的抗肿瘤作用。方法观察不同浓度中华芦荟多糖对移植性S180肿瘤小鼠和EAC荷瘤小鼠的抑瘤率,对EAC荷瘤小鼠肿瘤坏死因子(TNF)含量的影响,并以脾系数为指标,观察中华芦荟多糖对环磷酰胺(CTX)的增效减毒作用。结果不同浓度的中华芦荟多糖对S180荷瘤小鼠和EAC荷瘤小鼠的肿瘤均具有不同程度的抑制作用。结论中华芦荟多糖可显著改善CTX引起的机体生理机能紊乱,提高其抑瘤作用。     

芦荟多糖分析方法

介绍了芦荟多糖的分离、纯化方法以及芦荟多糖的组成和特征分析方法。     

星点设计-响应面法优化芦荟多糖提取工艺

文章采用了星点设计-响应面法优化了芦荟多糖的提取工艺。选取提取温度、提取时间、液料比为自变量,多糖得率作为因变量。优化出最佳提取工艺条件为:提取温度为39.22℃,提取时间为3.05 h,液固比为29.62 m L/g,在此优化条件下,多糖得率为9.704%。该方法优化芦荟多糖提取工艺具有简单、预测性好等特点。     

芦荟多糖的分离纯化与分析

芦荟多糖具有杀菌、抗辐射、抗肿瘤、降血糖和降血脂等多种药理作用,在医药、食品、美容保健等领域具有很大的潜在应用价值。综述了近年来国内外芦荟多糖研究的进展,主要包括其化学组成、分离纯化和分析方法等方面,为其进一步深入研究及新产品的开发提供理论参考。     

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。