阳离子壳聚糖和羧甲基纤维素对造纸沉淀碳酸钙填料的改性

沉淀碳酸钙(PCC)的改性对提高它在纸中的留着率并减少对纸张强度的负面影响具有重要意义.本文研究了阳离子壳聚糖和羧甲基纤维素对PCC的改性,并分析了PCC改性对其留着率和纸张抗张指数的影响.实验结果表明,阳离子壳聚糖与羧甲基纤维素的质量比为0.56时,聚电解质复合物的浊度最高,在此条件下聚电解质复合物改性的PCC水分散体上清液具有最小的浊度.与未改性PCC相比,改性后PCC在纸中的留着率更高,而且对纸张抗张指数的负面影响更小.     

壳聚糖/羧甲基纤维素缓释抗菌剂的制备及缓释抗菌性能表征

CaCl2作为交联剂,以天然可生物降解壳聚糖(CS)和和羧甲基纤维素(CMC)为原料,二甲酸钾(KDF)为目标药物,利用凝聚法制备壳聚糖/羧甲基纤维素/二甲酸钾缓释抗菌剂微球。经SEM、FT-IR、TGA分析表明:壳聚糖与羧甲基纤维素之间通过离子键形成聚电解质复合物,具有比天然壳聚糖、羧甲基纤维素更高的稳定性。溶胀测试表明制备的微球具有高pH敏感性,可对二甲酸钾起到良好的缓释效果。体外抗菌测试表明,制备的抗菌剂对大肠杆菌具有较高的抑菌率,有助于调节肠道pH值和微生物群的总数量平衡,有益于仔猪的健康生长。     

羧甲基纤维素-壳聚糖LbL空腔微胶囊的制备

微胶囊技术现已广泛应用于生物医药,环境保护,日用化工,农业科学及航空航天等领域,随着应用范围扩大,开发新技术与新方法制备微胶囊,使其具有更精确可控的结构已成为微胶囊技术发展的重大课题之一。选择两种生物相容性较好的天然聚电解质—羧甲基纤维素(CMC)和壳聚糖(CS),作为制备新型微胶囊的原料,利用聚阴离子羧甲基纤维素和聚阳离子壳聚糖之间的静电结合,成功制备出一种具有新结构的中空聚电解质微胶囊并初步研究了其形貌能基本性能。     

硼改性微粒硅溶胶助留助滤研究

研究了剪切力和CPAM、阳离子淀粉、硼改性硅溶胶用量对硼改性溶胶与阳离子淀粉或CPAM组成不同助留助滤体系的助留助滤效果的影响；同时研究了硫酸铝用量、pH值及电解质用量对助留助滤效果的影响。研究结果发现：阳离子淀粉／硼改性硅溶胶微粒助留体系的抗剪切能力优于阳离子淀粉一元助留体系。阳离子聚合物／硼改性硅溶胶微粒助留助滤体系的助留助滤效果优于一元助留滤体系，同时大大地改善了纸页的匀度。阳离子淀粉／硼改性硅溶胶微粒助留助滤体系在pH值4～8时，以及在松香施胶体系中硫酸铝用量≤3％时较为适用，该体系抗电解质干扰能力强。     

硼改性微粒硅溶胶助留助滤研究

研究了剪切力和CPAM、阳离子淀粉、硼改性硅溶胶用量对硼改性溶胶与阳离子淀粉或CPAM组成不同助留助滤体系的助留助滤效果的影响；同时研究了硫酸铝用量、pH值及电解质用量对助留助滤效果的影响。研究结果发现：阳离子淀粉／硼改性硅溶胶微粒助留体系的抗剪切能力优于阳离子淀粉一元助留体系。阳离子聚合物／硼改性硅溶胶微粒助留助滤体系的助留助滤效果优于一元助留滤体系，同时大大地改善了纸页的匀度。阳离子淀粉／硼改性硅溶胶微粒助留助滤体系在pH值4～8时，以及在松香施胶体系中硫酸铝用量≤3％时较为适用，该体系抗电解质干扰能力强。     

十六烷基三甲基溴化铵-羧甲基纤维素离子复合物的胶束性质研究

十六烷基三甲基溴化铵通过静电相互作用与羧甲基纤维素形成离子复合物胶束。电导率法测定离子复合物的最低聚集浓度为2.42×10-4mol/L。表面活性剂浓度达到聚电解质等电点时,复合物从溶液中析出沉淀。甲基橙的最大吸收波长发生蓝移,证明在复合物溶液中存在胶束的疏水结构。复合物粒径在环糊精加入后减小,溶液透过率增加。     

壳聚糖-丙烯酰胺接枝共聚物的制备

研究了壳聚糖与丙烯酰胺接枝共聚物（简称CAM）的制备、结构表征及对纸张的助留、助滤效果。文中还对接枝共聚物的助留、增强机理进行了探讨。结果表明,该接枝共聚物加入造纸浆料后,可通过对纸料电荷的中和以及接枝共聚物大分子的架桥作用产生很好的絮凝效果,同时壳聚糖的羟基、氨基与纤维通过氢键、离子键等结合使纸张的干强度损失减少,是一种性能优异的造纸助留剂。     

壳聚糖-聚阴离子复合絮凝剂的应用

壳聚糖与天然阴离子絮凝剂卡拉胶等进行复配用于红花水提液的絮凝试验,红外光谱分析表明壳聚糖分子上的NH3^＋与卡拉胶分子上的SO3^-通过静电相互作用而联结形成壳聚糖-卡拉胶聚电解质复合物.通过对红花水提液的絮凝试验,研究了不同聚阳离子-聚阴离子间进行复配以及复配方式、复配配比等条件对絮凝效果的影响,结果表明复配的絮凝剂其絮凝效果得到显著提高.     

纤维素/壳聚糖可生物降解膜的制备及力学性能

将纤维素粉加入壳聚糖的乙酸溶液中制成生物降解膜。研究了影响共混薄膜力学性能的因素。结果表明，在共混体系中加入一定量的羧甲基壳聚糖作为增容剂有助于提高薄膜的强度；在乙酸质量分数为2％、壳聚糖质量分数为4％、纤维素与壳聚糖的质量比为1：1，羧甲基壳聚糖与壳聚糖质量比为1：15，共混搅拌20min的条件下，制得的共混膜拉伸强度达到88MPa。     

羧甲基甲壳素助留助滤剂的制备及性能

以甲壳素(CH)为原料、氯乙酸钠为醚化剂,合成了不同取代度(DS)的水溶性羧甲基甲壳素CCHx(下标x表示取代度,x=0.4,0.5和0.6),并用IR、XRD对其结构进行了表征。结果表明:羧甲基基团成功引入到了CH骨架上,并且破坏了结晶区。考察了CCH对纸浆的助留助滤性能,结果表明:CCH的DS越大,其助留助滤效果越好。当CCH0.6加入量为0.5%(以纸浆干重计,下同)时,留着率由没添加CCH0.6时的35%提升至70%,打浆度由33.0°SR下降至23.0°SR。进一步加入0.5%(以纸浆干重计,下同)的聚合氯化铝(PAC),与CCH0.6构建二元体系,并对其助留助滤性能进行了测试,结果表明:CCH0.6/PAC二元体系的留着率由CCH0.6单独体系的70%提升至80%,打浆度由23.0°SR轻微下降到21.5°SR。     

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.     

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.     

ICP-MS法测定地球化学样品中As、Cr、Ge、V等18种微量痕量元素的研究

建立了测定地球化学样品中包括As、Cr、Ge、V等18种微量、痕量元素的ICP-MS方法。地化试样用HF-HNO3混酸分解后,以1 1 HNO3溶解干渣。由于制样不使用盐酸,避免了Cl对As、Cr、Ge、V的质谱干扰。用国家一级地球化学标准物质GBW 07309制备溶液优化仪器工作参数,并用于校准。方法测定限(6s)为:0.007~6.4μg/g,精密度(RSD%,n=12)为:29%~9.4%,经过国家一级地球化学标准物质的分析验证,结果与标准值吻合。方法已应用于国土资源调查的试样分析。