聚苯硫醚熔体结晶自成核作用的研究--聚苯硫醚多次扫描的熔体结晶行为

用差示扫描量热法多次扫描研究聚苯硫醚（PPS）在不同的熔融温度（Tmelt)以及交变温度熔融对其结晶行为的影响。结果表明：PPS的结晶温度（Tc) 随Tmelt提高而降低；但Tmelt低时，PPS的Tc随扫描次数增加而提高。随扫描次数增加，PPS呈现多结晶峰。同一试样交变温度熔融，低温熔融结晶的Tc总量比高温熔融结晶的Tc高，而且与扫描次数无关，归结于PPS的自成核作用。     

酰胺类β晶型成核剂对PP结晶性影响

研究了新型酰胺类β成核剂对聚丙烯（PP）结晶性能的影响。用差示扫描量热计（DSC）和X射线衍射仪（XRD）对其结晶形态进行了表征，DSC研究表明，该成核剂的加入可以诱导PP中α晶向口晶转变；X射线衍射研究发现，当成核剂加入质量分数为0．3％时，β晶型的相对含量可达到87%，与DSC的研究结果一致。考察了冷却速率对结晶温度和结晶峰温度的影响，结果表明该成核剂的加入使PP结晶向高温方向偏移，结晶速度加快。     

超声波在丙烯酸固相接枝聚丙烯中的应用

利用超声波促进固相接枝反应的原理，研究丙烯酸（AA）接枝聚丙烯（PP）的反应条件：超声波作用时间、接枝反应温度、引发剂过氧化苯甲酰（BPO）及AA用量等对接枝率的影响。研究表明：超声波能有效地促进固相接枝反应的进行。其最佳反应条件是：超声波的作用时间为30min，BPO与AA的用量分别为4％和15％，反应温度为110℃。在上述反应条件下，可以得到接枝率为6％的接枝产物AA接枝PP（PP－g－AA）；并用硅灰石填充含有PP-g-AA的PP复合材料，其力学性能明显优于不含PP－g－AA的硅灰石填充的PP复合材料。     

聚丙烯的高性能化研究

在小型反应器内合成了不含及含有成核剂的聚丙烯(PP)、双峰聚丙烯(BMPP)和聚丙烯共聚物(PPc)，并用纳米CaCO3改性PPc。研究结果表明：釜内成核的PP和BMPP的弯曲模量和热变形温度显著增加，结晶温度和结晶速率明显提高，BMPP的拉伸强度也较PP大幅增加；但成核剂对PPc的性能影响不大，而加入纳米CaCO3后则使PPc的力学性能和结晶温度同步显著增加。     

DSC技术在PE100树脂分析中的应用

采用差示扫描量热法（DSC）研究了低聚物对高密度聚乙烯管材PE100热性能的影响,并且对比分析了5种国内外树脂的热行为。结果表明,通过改变树脂中低聚物配比的方法可以控制树脂的结晶行为。当等温结晶温度升高时,树脂的DSC热分级曲线的低温熔融峰面积和高温熔融峰面积的比例会发生变化。国外进口树脂的低温熔融峰面积相对较低。     

超声波强化铝酸钠结晶工艺

实验考察了超声波强化铝酸钠结晶过程中超声波频率和功率对铝酸钠结晶和晶体形貌的影响,获得了超声波强化铝酸钠溶液结晶的最优工艺条件. 结果表明,超声波能显著强化铝酸钠结晶过程,在结晶温度60℃、超声频率45 kHz、功率100 W的最优工艺条件下,结晶产品为水合铝酸钠,分子式为4NaAlO2×5H2O,晶体随反应条件不同可呈现片状、八面体、无规则等多种形貌. 超声波作用使结晶诱导期缩短66%,溶液的电导率提高1.5倍,溶液中SiO2浓度降至5 g/L.     

PP中成核剂的异相成核作用的热稳定性

用差示扫描量热计（DSC）研究了聚丙烯（PP）中不同类型成核剂的异相成核作用的热稳定性,观察到随扫描次数增加,纯PP的成核作用稳定,降温结晶温度基本不变,而有机磷酸盐类成核剂成核PP的结晶温度比纯PP的高,而且异相成核作用受DSC扫描次数的影响也很小,但山梨醇类成核剂成核PP的异相成核作用随DSC扫描次数增加,结晶温度逐步降低,表明其异相成核作用对热不稳定。     

振动共混对PC/PP多重结晶行为的影响

在传统转矩流变仪上叠加机械振动帛成了振动共混流变仪，叠加机械振动的流动影响共混物的相形态，因此影响了PC／PP的多重结晶行为。DSC和偏光显微联用分析发现，所有峰对应的结晶都是异相成核，共混频率或振幅增高，减小分散相相畴尺寸，PP粒子的异相核会向PC迁移，所以制备的共混物的低温结晶峰越强，而高温结晶峰减弱，共混振幅很大时，中等尺寸粒子界面附生非均相成核等效增加了较高温度成核率，结晶温度较高。     

超声波作用下液滴的冷却冻结规律

超声波液体辅助冻结在食品、海水淡化及冰蓄冷等方面的应用得到了广泛关注。结合声场理论，在对液滴界面处热质传递分析的基础上，建立了超声波作用下的液滴冷却冻结数学模型，讨论了不同超声波频率、强度及作用时间对液滴界面处热质传递的影响，得到了超声波作用下液滴的冷却冻结规律。结果表明：超声波作用下界面处的传质系数随着超声波强度的增加而增大，但随超声波频率的增加而减小；在液滴冷却冻结过程中，质量传递与热量传递的方向相同，液滴的冷却冻结在超声波作用下得到了强化。在超声波频率为20000 Hz（强度为400 W·m^-2），经过相同的时间（60 s），超声波作用下的液滴温度比无超声作用的温度低2.0~2.5℃。研究将有助于深入理解超声波辅助冷却冻结机理，并为其工程应用提供了指导和参考。     

小角激光散射法研究LLDPE/BR、LLDPE/PP的结晶

利用小角激光散射仪研究了LLDPE／顺丁橡胶（BR）、LLDPE／聚丙烯（PP）的结晶。结果表明，BR或PP的加入影响了LLDPE的结晶行为，改变了体系球晶的大小，且随着BR或PP用量的增加，体系的球晶逐渐增大；在较高结晶温度下，随着BR用量的增加，LLDPE／BR体系的结晶诱导期变化明显；而PP用量的改变对LLDPE／PP体系的结晶诱导期几乎没有影响，但LLDPE／PP体系对结晶温度敏感；LLDPE／BR体系和LLDPE／PP体系在等温结晶过程中的散射图形变化相似，且LLDPE与PP没有形成共晶现象。     

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。