茶多糖的纯化工艺研究

实验研究了茶多糖的提取纯化工艺,主要考察醇沉、除蛋白、脱色工艺条件,得适宜的纯化工艺:提取液浓缩至1/4倍体积后,加入4倍体积95%乙醇沉淀6h,离心得茶多糖粗品。多糖粗品溶于水,并用Sevag法去除蛋白质,多糖溶液与Sevag试剂比为4:1,析出的蛋白质离心除去。清液最后经非极性大孔吸附树脂ADS-8脱色,冷冻干燥得到茶多糖制品,多糖含量65%,产率2.05%。     

Box-Behnken响应面法优化阿里红总多糖水提醇沉工艺

分别采用单因素实验和Box-Behnken响应面法对阿里红总多糖水提醇沉工艺条件进行优化。以苯酚-硫酸法测定阿里红总多糖含量,在单因素实验基础上,选择多糖提取率为评价指标,以浸泡时间、提取时间、加水倍量作为考察因素,采用Box-Behnken响应面法优化水提工艺条件;选择多糖含量为评价指标,以醇沉浓度、醇沉时间、浓缩倍数为考察因素,采用Box-Behnken响应面法优化醇沉工艺条件;采用Sevage法对阿里红粗多糖进行脱蛋白。得到最佳水提工艺条件为:加水10倍,浸泡时间1.5 h,提取1.0 h,提取1次;最佳醇沉工艺条件为:浓缩倍数10倍,醇沉浓度80%,醇沉时间12 h;Sevage法脱蛋白,蛋白脱除率为42.4%,多糖保留率为61.4%。建立的阿里红总多糖提取纯化工艺简单可靠。     

水提醇沉法提取黄芪中黄芪多糖的工艺优化及含量测定

为得到高效的黄芪多糖提取方法,以提高黄芪多糖的提取效率。采用全面实验法,研究黄芪多糖提取时的温度和时间,以及醇沉时乙醇的浓度对提取率的影响;并用液相色谱法测定黄芪多糖的纯度。实验发现提取黄芪多糖最佳的工艺条件是:温度100℃,水提取2 h,醇沉时乙醇体积分数为90%,黄芪多糖粗提物的质量含量是42.9 mg/g(4.29%),纯度为31.2%。实验结果表明,黄芪多糖的提取效率有所提高,对黄芪多糖的工业化提取奠定了基础。     

灵芝多糖提取及纯化工艺研究

为了优化制备高纯度灵芝多糖的提取及纯化工艺,获得高纯度的灵芝多糖药学研究用样品。以灵芝子实体为原料,药用纯化水为溶剂,以固形物含量和多糖含量为考察指标,通过对比研究确定灵芝水提物生产的最优工艺条件。灵芝水提物制备的最佳工艺条件为:料液比1︰15、提取两次、第一次提取时间为4 h、第二次提取时间为3 h,得到水提物收率6.54%,多糖含量9.1%。灵芝水提物通过分级醇沉方法纯化分离灵芝多糖,以多糖含量为考察指标,对比两组不同梯度的体积分数醇沉工艺,确定灵芝多糖分级醇沉的的最佳工艺条件。灵芝水提物分级醇沉的最优工艺条件为30%、60%和90%三个醇沉体积分数,通过分级醇沉可以将水提物中80%以上的灵芝多糖纯化分离出来,其中60%、90%体积分数醇沉得到的灵芝多糖2#、灵芝多糖3#的多糖含量达到25%以上。     

超声辅助提取葫芦巴中多糖的工艺研究

采用超声辅助水提醇沉法提取葫芦巴中多糖,考察提取时间、乙醇体积、乙醇浓度、料液比对多糖提取率的影响。结果表明,最佳提取工艺参数为:料液比1∶40 g/m L,乙醇浓度90%,乙醇体积倍数40,超声提取时间1.5 h。在最佳提取条件下,葫芦巴多糖提取率1.34 mg/g,多糖纯度达67%。     

超声辅助提取葫芦巴中多糖的工艺研究

采用超声辅助水提醇沉法提取葫芦巴中多糖,考察提取时间、乙醇体积、乙醇浓度、料液比对多糖提取率的影响。结果表明,最佳提取工艺参数为:料液比1∶40 g/m L,乙醇浓度90%,乙醇体积倍数40,超声提取时间1.5 h。在最佳提取条件下,葫芦巴多糖提取率1.34 mg/g,多糖纯度达67%。     

无患子皂苷提取工艺的优化

采用水提醇沉法提取无患子皂苷,以得到无患子皂苷的量为评价指标,用正交设计试验考察醇沉工艺中初膏质量分数、乙醇体积分数和醇沉温度3个因素的影响。结果表明:初膏质量分数是影响无患子皂苷提取量的主要因素,乙醇体积分数和醇沉温度是影响其提取量的次要因素;提取工艺的较优方案为初膏质量分数25%,乙醇体积分数70%,醇沉温度30℃,在此条件下,100g无患子果皮可提取3.6591g的皂苷。     

秦岭岩白菜多糖的提取纯化工艺研究

以秦岭岩白菜多糖的含量和得率为指标,采用正交实验对秦岭岩白菜多糖的提取纯化工艺进行了优化。确定秦岭岩白菜多糖的最佳提取工艺为：用20 BV水在90℃提取3次,每次0.5 h;最佳纯化工艺为：用4 BV 70％(体积分数)乙醇醇沉24 h。该优化提取纯化工艺简便、合理、可行。     

灵芝多糖分离工艺的比较研究

研究了灵芝子实体水提液不同沉淀分离多糖的工艺。结果表明:醇沉法收率高,但需要将灵芝子实体水提液浓缩至小体积,以提高收率、减少乙醇用量;氢氧化钙沉淀法不对水提液浓缩,但要达到较高的收率需要大量的沉淀剂氢氧化钙;采用经过改进的氢氧化钙沉淀法,不对水提液浓缩,通过加入沉淀剂聚合硫酸铁,大幅度减少了氢氧化钙的加入量,多糖沉淀分离完全,收率与醇沉法相近。     

白及多糖提取工艺优化

采用水提醇沉法,提取白及多糖,用乙醇沉淀,考察加水量、浸泡时间、提取时间、提取温度、提取次数及醇沉浓度对多糖提取率的影响。结果表明,6~16μg/m L(r2=0.999 0),平均加样回收率为100.79%(RSD=0.765%,n=9),精密度2.388%;所得最佳提取工艺为加10倍量水,浸泡90 min,90℃水浴提取2次,每次90 min,75%浓度乙醇醇沉,静置,过滤,即得。     

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.     

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.     

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.     

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.     

Novel polyurethane coating technology through glycidyl carbamate chemistry

Glycidyl carbamate chemistry combines the excellent properties of polyurethanes with the crosslinking chemistry of epoxy resins. Glycidyl carbamate functional oligomers were synthesized by the reaction of polyfunctional isocyanate oligomers and glycidol. The oligomers were formulated into coatings with several amine functional crosslinkers at varying stoichiometric ratios and cured at different temperatures. Properties such as solvent resistance, hardness, and impact resistance were dependent on the composition and cure conditions. Most coatings had an excellent combination of properties. Studies were carried out to determine the kinetics of the curing reaction of the glycidyl carbamate functional oligomers with multifunctional and model amines. Detailed kinetic analysis of the curing reactions was also undertaken. The results indicated that the glycidyl carbamate functional group is more reactive than a glycidyl ether group. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, on October 27–29, 2004, in Chicago, IL.     

Highly moisture-proof polysilsesquioxane coating prepared via facile sol-gel process

A highly moisture-proof polysilsesquioxane coating was obtained from a new bis-silylated precursor, which was synthesized from 3-aminopropyltriethoxysilane (APTES) and m-xylylene diisocyanate (m-XDI) in tetrahydrofuran (THF) and verified by ¹H MAS NMR. For direct comparison purposes, an SiO₂ coating was also prepared by the Stöber method using tetraethoxysilane (TEOS) as the reactant. Interestingly, the coating obtained from the polysilsesquioxane sol exhibited a much higher moisture resistance capability than its counterpart, which was attributed to its more compact feature between nanoparticles as characterized by N₂ absorption experiment and transmission electron microscopy (TEM). Furthermore, its high transparency of about 92% showed potential for application in the protection of optical crystals.