玉米麸皮中阿拉伯木聚糖的提取、结构及性质

采用碱-过氧化氢法从玉米麸皮中提取阿拉伯木聚糖(AX),并考察其基本性质。研究发现:0.5 mol/L Na OH溶液提取所得阿拉伯木聚糖色泽浅、产量较高且未发生降解;阿拉伯木聚糖主要由阿拉伯糖和木糖单元组成,还含有少量葡萄糖和半乳糖单元;阿拉伯木聚糖从215℃开始发生热分解,350℃时分解完全;阿拉伯木聚糖还具有一定的增稠效果;此外,AX可用来制备水包油型乳液,所制得的乳液十分稳定。     

玉米麸质阿拉伯木聚糖的疏水改性

从玉米麸质中提取了半纤维素阿拉伯木聚糖(AX),以1-溴代丁烷、1-溴代十二烷、1-溴代十六烷为烷基化试剂,通过醚化反应制备了疏水改性阿拉伯木聚糖(Cn-AX)。采用傅里叶红外光谱和1H NMR表征了改性阿拉伯木聚糖的结构。利用流变仪研究了改性前后阿拉伯木聚糖水溶液的粘度性质,发现疏水改性阿拉伯木聚糖水溶液由于长碳链的聚集,粘度显著升高。     

疏水改性玉米麸皮阿拉伯木聚糖的性能研究

采用碱-过氧化氢法从玉米麸皮中提取碱溶性阿拉伯木聚糖(AX),然后分别用1-溴代丁烷、1-溴代十二烷和1-溴代十六烷对其进行疏水改性得到两亲性的烷基化阿拉伯木聚糖(C_n-AX)。利用荧光分子探针、动态光散射、扫描电子显微镜和流变仪对C_n-AX水溶液的性质进行研究,发现Cn-AX在一定质量浓度时水溶液中形成缔合聚集体。疏水缔合使C_n-AX水溶液的黏度高于AX水溶液。此外,通过制备一系列O/W型乳液,对AX和C_n-AX的乳化能力进行了评价。结果表明,乳液的稳定性受C_n-AX的烷基链长度和质量分数的影响,并且C_(16)-AX的乳化性能优于常用的Tween 80。     

紫外吸收剂阿拉伯木聚糖肉桂酸酯的合成和表征

从玉米麸皮中提取水溶性的阿拉伯木聚糖(AX),以DMF为溶剂,三乙胺为缚酸剂,醚化产物与肉桂酰氯反应,生成高分子紫外吸收剂阿拉伯木聚糖肉桂酸酯(AX-CM)。UV检测表明,AX-CM在283 nm处有较高的紫外吸收,且光稳定性良好。     

玉米麸质阿拉伯木聚糖在水溶液中的聚集和构象

从玉米麸皮中提取碱溶性阿拉伯木聚糖(AX)并用乙醇分级。用体积排除色谱-多角度激光光散射联用(SEC-MALS)和动态光散射(DLS)研究了AX的构象和聚集。碱溶性麸质AX的相对分子质量随均方旋转半径(Rg)的变化可以用Mw~Rdfg表示。玉米麸质AX分子链的分形维数(df)为1.47,其结构因子ρ=Rg/Rh为1.70。忽略分子间作用,根据"蠕虫链"模型可以估算出玉米麸质AX的持久长度(Lp)为1.72 nm。即使在很稀的溶液中,玉米麸质AX也可以形成紧密的聚集,其df在3.0左右。     

双亲阳离子阿拉伯木聚糖的合成及其在香波中的应用

以玉米麸皮阿拉伯木聚糖为原料,以环氧氯丙烷和不同烷基链长的叔胺作为季铵化试剂,在碱性条件下,在水溶液体系里合成双亲阳离子阿拉伯木聚糖。通过核磁共振氢谱和碳谱对其结构进行表征。随烷基链长的增加,双亲阳离子阿拉伯木聚糖溶液粘度增加。添加了双亲阳离子阿拉伯木聚糖的洗发水有着良好的帮助硅油沉积的能力,同时有着良好的梳理性能,而且烷基链越长,取代度越高,帮助硅油沉积的能力越强,干梳和湿梳性能也越好。     

双亲阳离子阿拉伯木聚糖的合成及其在香波中的应用

以玉米麸皮阿拉伯木聚糖为原料,以环氧氯丙烷和不同烷基链长的叔胺作为季铵化试剂,在碱性条件下,在水溶液体系里合成双亲阳离子阿拉伯木聚糖。通过核磁共振氢谱和碳谱对其结构进行表征。随烷基链长的增加,双亲阳离子阿拉伯木聚糖溶液粘度增加。添加了双亲阳离子阿拉伯木聚糖的洗发水有着良好的帮助硅油沉积的能力,同时有着良好的梳理性能,而且烷基链越长,取代度越高,帮助硅油沉积的能力越强,干梳和湿梳性能也越好。     

玉米芯木聚糖硫酸酯化条件的研究

用碱提法从玉米芯中提取木聚糖,采用氯磺酸吡啶法进行硫酸酯化,通过正交试验确定最佳工艺条件为:吡啶与氯磺酸摩尔比1∶1,温度65℃,时间6h;木聚糖硫酸酯wisX-S通过DEAESepharoseFF层析柱分离得到一个相对分子量为1.3×104的组分,硫酸基取代度为2.24。对此木聚糖硫酸酯进行红外光谱分析,结果显示在波数1259、1228和813cm-1处分别有S=O和C-O-S键的特征吸收峰。     

双活性磺酸基蔗渣木聚糖邻苯二甲酸酯的合成与表征

以蔗渣木聚糖为主要原料,经两步酯化反应合成磺酸基蔗渣木聚糖邻苯二甲酸酯,考察反应条件对合成反应的影响,并通过红外光谱(FT-IR)、X射线衍射(XRD)、热重分析(TG-DTG)和扫描电镜(SEM)对蔗渣木聚糖经双酯化改性前后的样品进行表征。结果表明,较优的反应条件为:第一步以邻苯二甲酸酐为羧酸酯化剂,三乙胺为催化剂,在三乙胺与N,N-二甲基甲酰胺体积比为1:16,蔗渣木聚糖单元和邻苯二甲酸酐物质的量之比为1:2时,于80℃下反应4 h,经催化羧酸酯化合成单活性蔗渣木聚糖邻苯二甲酸酯;第二步以氨基三磺酸钠为酯化剂,在碱性条件下,蔗渣木聚糖邻苯二甲酸酯与NaNO_2的质量比为1:2时,于50℃下反应4 h,合成了双活性磺酸基蔗渣木聚糖邻苯二甲酸酯。双酯化后的磺酸基蔗渣木聚糖邻苯二甲酸酯的热稳定性增强,其分子表面形貌更加紧密。     

硫酸盐竹浆 ECF 漂白过程中糖类 组分变化的研究

应用高效液相色谱法研究了硫酸盐竹浆 ECF 漂白过程中二氧化氯漂白段糖类组分的变化情况。结果表明,葡聚糖、木聚糖和阿拉伯聚糖在二氧化氯漂白过程中有不同的降解率,葡聚糖降解率只有 0.133%,而木聚糖的降解率为 0.907%,阿拉伯聚糖的降解率达 79.77%,明显高于葡聚糖的降解率。     

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.     

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.