扁平形聚酯纤维结构和性能研究

对扁平形聚酯纤维和圆形聚酯纤维的结构和性能进行了研究。结果表明 ,扁平形初生丝的双折射比圆形丝大 ;扁平丝的比表面积、沸水收缩率和功系数都比圆形丝大 ,而其杨氏模量和断裂强伸度却比圆形丝小 ,以致使扁平形聚酯纤维具有更好的干爽感和柔韧性     

不同农药助剂的初级生物降解性研究

以新型复配农药助剂——松脂基表面活性剂1号和2号以及传统农药助剂壬基酚聚氧乙烯醚、松香酸聚乙二醇酯和直链十二醇聚氧乙烯醚为目标物,通过实验考察了不同类型农药助剂的初级生物降解特性。8 d的生物降解实验结果表明,松脂基表面活性剂1号的初级生物降解度为79.1%,松脂基表面活性剂2号的初级生物降解度为82.4%,松香酸聚乙二醇酯的初级生物降解度为84.2%,壬基酚聚氧乙烯醚的初级生物降解度为91.1%,直链十二醇聚氧乙烯醚的初级生物降解度大于99%。新型复配农药助剂的组成结构更为复杂,其初级生物降解度要低于直链醇类、酚类的聚氧乙烯醚及单一结构酸类的聚乙二醇酯等农药助剂。     

Possible Explanations of Transient Neck Formation between Pairs of (100) Faceted Particles

Rankin and Boatner have observed that (100) faceted MgO particles in contact along either corners or edges developed, on heating, necks that initially grew, but then shrank and broke. General thermodynamic models are provided that predict this transient neck formation for any cubic particles that share only a small fraction of an edge and for particles that share an edge that is less than 0.6 times as long as the orthogonal edges. A third model, which assumes that reaction of MgO particles with their carbon substrate removes MgO from the MgO–carbon interface at a constant rate, explains the observation that the neck shrinkage rate greatly exceeds the neck growth rate. Application of the theory to explaining the seeming prevalence of rounded surfaces in sintering powders is described.     

Suppression of Cavity Formation in Ceramics: Prospects for Superplasticity

Ceramics exhibit macroscopic stress/strain rate relations that should lead to superplastic extension. However, premature fracture is normally encountered, due to the formation and growth of grain-boundary cavities. Thus, cavity nucleation and growth were analyzed in an attempt to identify microstructures and/or strain-rate regimes that would suppress cavity evolution and hence allow superplasticity. Analysis of cavity nucleation indicates that fine-grained materials devoid of grain-boundary amorphous phases and inclusions should sustain substantial deformation rates without nucleating cavities, especially if solid-solution additions that encourage rapid grain-boundary diffusion (while not excessively decreasing surface energy) are identified. The analysis of void growth indicates that high relative surface diffusivities are also desirable, indicating that alloy additions that do not depress (and probably enhance) the relative surface diffusivities must be selected.     

单体转化率对聚氯丁二烯微观结构的影响

乳液聚氯丁二稀的微观结构与聚合条件有关.本文通过红外光谱、核磁共振波谱测定,考察了硫调型氯丁橡胶微观结构与聚合转化率之间的关系.结果表明,随着单体转化率的提高,聚合物中反式-1,4-结构含量减少,而顺式-1,4-、1,2-及3.4-结构含量增多。同时.1,4-结构中的头-头、尾-尾联接也增多.即大分子链的规整度下降.剖析日本和国内相应产品表明,国内产品中1.2-结构含量较高,可能与控制聚合转化率较高有关。     

A Multi-Component Species Identifying Pheromone in the Goldfish

Although it has been established that sexually-immature goldfish and their relatives recognize members of their own species by using chemicals that they release, the identity of this cue(s) and whether it might be produced and used by other life stages is not yet known. To address this question, this study tested the behavioral responses of sexually immature and mature goldfish to each other’s body washings, their sensitivity to this cue, the role of the olfactory sense in detecting it, and whether it is comprised of either polar and/or non-polar compounds. Tests that used two-choice mazes discovered that juvenile, immature, mature male, and mature female goldfish all release and respond to a common chemical cue(s). Dilution studies next demonstrated that this cue is active when diluted over 10 times and thus capable of functioning as a short range attractant/identifier. Olfactory occlusion demonstrated that it is detected by the olfactory sense. Finally, chemical fractionation demonstrated that it is comprised of both polar and non-polar components but likely does not include bile acids. Together, these results suggest that all life stages of goldfish use a complex multicomponent pheromonal odor to discern species identity, and that this odor has the potential to function with hormonal metabolites to identify sexual condition in behaviorally active fish of many species.     

T300与国产PAN基炭纤维的结构和性能研究

采用WARD、SAXS、RAMAN、XPS等测试技术对T300和国产聚丙烯腈基炭纤维(PAN-CF)的组织结构及化学组成进行了表征,分析了材料的微观组织结构与宏观性能的关系.结果表明,和T300相比,国产炭纤维的乱层石墨层间距d002略小,微晶尺寸La,Lc略大,微孔尺寸较大,大孔洞所占百分比较多,微孔含量较低.国产炭纤维表面含氧官能团含量较低,为31.35%.表面活性小.     

Reduction in visual science: A philosopher's View

Suppose that we had a complete, utopian understanding of the workings of the nervous system. Would we thereby know all that there is to know about subjective sensory experience? It has been maintained that we would not, and that although sensory experiences are caused by brain events, they cannot be identical with these events. We shall consider three arguments that purport to lead to this conclusion, and discover that each of them is defective. It will then be argued that the question of whether sensory experiences are identical with brain events is an empirical one, to be settled by future science. An affirmative answer will require that the phenomenology be properly regimented, and shown to be isomorphic with an appropriate subset of neural processes. Although the realization of these conditions must be regarded as utopian, contemporary visual science has made progress in this direction.     

氨基磺酸系高效减水剂ASP缓凝性能研究

氨基磺酸系高效减水剂是一种具有缓凝性能的新型高效减水剂，研究的结果表明：氨基磺酸系高效减水剂ASP分散能力强，流动度损失小，120min内相对流动度损失率仅为7．7％，远小于萘系减水剂FDN；掺加0．5％ASP的水泥净浆初凝和终凝时间较空白分别延长1h 55min和6h 30min，水泥水化放热峰较空白推迟约7h，但不能明显降低水化放热峰值；混凝土28d抗压强度为空白的1．38％，其混凝土试块微结构比掺FDN的试块更为均匀、细密，基本上已看不出网状结构。氨基磺酸系高效减水剂适合配制用于泵送的高强高性能混凝土。     

An Engineer Asks: Is it Really More Important that Paint Stays Stuck on the Outside of an Aircraft than that Glue Stays Stuck on the Inside?

The purpose of this article is to draw attention to two problems encountered with modern aircraft: the difficulties in making adhesive and paint adhere to composite substrates and the lack of any after-the-fact inspection that can prove that there will not be any interfacial failures at some time during the service life. It is also observed that the response to paint peeling off is more rapid and thorough than to a discovery of separations between internal components that were once believed to have been bonded together. Because there is so much similarity between the processes of making paint and adhesive adhere, it is suggested that some of the efforts to improve adhesion of the paint might also help improve the processes for making adhesives stick. The article focuses on a series of anecdotes about problems and their resolutions, with the hope that the solutions might help others solve or avoid future such problems. It is pointed out that the cost of improving the adhesion of both paint and adhesive has always been insignificant in comparison with the sometimes enormous costs incurred as a result of fleet-wide occurrences of what were perceived to be bond “failures” but which should more properly be characterized as initially undetected nonbonds. A critical issue is the acknowledged absence of any nondestructive inspection capable of distinguishing between bonds that will “fail” in service and those that will not. Experience has shown that none of the apparent interfacial failures to date have occurred on grit-blasted surfaces. Equally, it must be conceded that not all of the bonded composite structures made using peel-ply surfaces can be expected to fail, even though those associated with released peel plies or prebond moisture probably will, because these conditions have been associated with so many of the past failures. The distinction between interfacial failures and impact damage to properly bonded structures is that the former can extend throughout the entire structure, whereas the broken fibers and interlaminar matrix failures associated with the latter will not extend far beyond the impact area. This is one reason why it is so important to use only surface preparations that ensure the absence of interfacial failures. It is also noted that there is no counterpart, for the bonding of composite structures, of the peel-type test that was so instrumental in solving the equivalent bonding problem that was widespread in bonded metal structures some 30 years ago. It is recommended that there should be, because the use of only shear-load tests has been found to be insufficient to ensure bond durability for both metallic and composite structures.     

Models of confined growth

Models based on boundary nucleation and growth provide good fits to the kinetics of hydration of cement phases, but the models indicate that the degree of hydration is smaller than the measured value. This could mean that the models do not capture the physics of the problem, or that the wrong models have been applied. This paper reviews the available models for boundary nucleation and growth, with emphasis on those that describe growth confined within boundaries (e.g., precipitation in capillary pores bounded by unreacted cement particles). It is shown that they all predict a degree of reaction at the peak that is inconsistent with experiments, so neglect of confinement is not the main problem. The discrepancy can be resolved by assuming that the assemblage of hydrates only contains 40–50% solids, which may mean that the hydrates exhibit dendritic growth.     

Effects of crosslinked polycarboxylate superplasticizers with crosslinking agent containing ester and amide groups on the properties of cementitious systems

Herein, crosslinked polycarboxylate superplasticizers were synthesized using acrylic acid, sodium methylallyl sulfonate and methyl polyethylene glycol acrylate as monomers, and monomers that contain either ester or amide groups as crosslinking agents. The superplasticizers that were synthesized from the ester- and amide-based crosslinking agents were respectively denoted as SP-E and SP-N. In addition, a series of performance characterizations were carried out to explore the influence of different functional groups in crosslinking agents on the performance of superplasticizers. Fluidity test results showed that the dispersibility and fluidity retention of cement pastes treated with the SP-E were better than those of cement pastes treated with SP-N. Meanwhile, the viscosity of the sample containing SP-E was lower than that containing SP-N. In addition, the amount of the two superplasticizers that had become adsorbed onto the surfaces of cement particles also differed, and in this case the adsorption capacity of SP-E was greater than that of SP-N. X-ray diffraction, thermogravimetric analysis, and scanning electron microscopy tests showed that the ester-group based SP-E superplasticizers promoted cement hydration to a greater degree than that was achieved with their amide-bearing SP-N counterparts. This study would provide valuable insight for the development of crosslinked polycarboxylate superplasticizers.     

羧甲基化碱木质素对农药的吸附分散作用机理

为了揭示羧甲基化碱木质素CML较磺化碱木质素（SAL）对农药具有更好分散性能的原因,测定了CML和SAL的亲水基含量、相对分子质量及纯水在木质素涂层的接触角,发现CML的亲水性弱于SAL。对比了两种木质素分散剂在多菌灵颗粒上的吸附等温线,发现CML的吸附量比SAL大,并采用Langmuir、Freundlich方程进行拟合,可知CML的吸附能力大于SAL,说明木质素与农药之间的吸附可能以疏水吸附为主。进一步采用Gaussian模拟计算木质素分散剂与多菌灵的π-π吸附作用力,结果表明羧甲基化碱木质素更易与农药形成稳定π-π作用,进一步促进吸附。亲水性较弱的CML由于与农药具有更强的吸附亲和力,因而吸附量大,对农药颗粒Zeta电位的提高更大,从而具有更好的分散性能。     

高效塔填料——共轭环的性能研究

本文总结了我国自行开发的高效散堆填料——共轭环的流体力学与传质性能,论述了共轭环的结构特点.用φ38塑料共轭环、鲍尔环、阶梯环做对比实验,其结果为:共轭环的每米压强降比阶梯环低40-45%、比鲍尔环低50—55%,共轭环的传质单元高度比阶梯环低15%、比鲍尔环低30%,即共轭环的流体力学和传质性能均比阶梯环、鲍尔环优良.     

Effects of pore mutations and permeant ion concentration on the spontaneous gating activity of OmpC porin

Porins are trimers of ß-barrels that form channels forions and other hydrophilic solutes in the outer membrane ofGram-negative bacteria. The X-ray structures of OmpF and PhoEshow that each monomeric pore is constricted by an extracellularloop that folds into the channel vestibule, a motif that ishighly conserved among bacterial porins. Electrostatic calculationshave suggested that the distribution of ionizable groups atthe constriction zone (or eyelet) may establish an intrinsictransverse electrostatic field across the pore, that is perpendicularto the pore axis. In order to study the role that electrostaticinteractions between pore residues may have in porin function,we used spontaneous mutants and engineered site-directed mutantsthat have an altered charge distribution at the eyelet and comparedtheir electrophysiological behavior with that of wild-type OmpC.We found that some mutations lead to changes in the spontaneousgating activity of OmpC porin channels. Changes in the concentrationof permeant ions also altered this activity. These results suggestthat the ionic interactions that exist between charged residuesat the constriction zone of porin may play a role in the transitionsbetween the channel's closed and open states.     

Studies on fibers spun from poly(vinyl alcohol‐b‐acrylonitrile) emulsions prepared by ultrasonic technique. II. Properties of the fibers

The moisture content of poly(vinyl alcohol‐b‐acrylonitrile) fibers decreases with an increasing hydrophobic AN content and crystallinity of the fibers; however, the copolymer fiber with 26.94% AN, drawn × 5, and heat‐treated at 200°C has a moisture content value slightly lower than that of commercial PVA fiber, but much higher than that of commercial PAN fiber. The block copolymer fibers have a water‐retention value higher than that of commercial PVA fiber, owing to the presence of voids in these fibers, and have a stronger wicking ability than that of commercial PVA, PAN fibers, and wool and cotton mainly due to the grooved surface and bulk porous morphology of the fibers. The tensile strength of the copolymer fibers with an appropriate AN content are lower than that of commercial PVA fiber, but higher than that of commercial PAN fiber and much higher than that of wool and cotton. The melting temperatures of the copolymer fibers increase with increasing heat‐treatment temperature. The copolymer fibers possess a lower peak cyclizing temperature than that of the PAN fiber and have a higher thermal stability than that of both PVA and PAN fibers. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 989–994, 2001     

红外光谱法(IR)与热分析(DSC)联用分析鉴定塑料材料

对于采用红外光谱法（IR）较难正确鉴定典型试样，与热分析（DSC）相结合进行分析鉴定，得到了正确的结果，从而说明IR与DSC相结合方法是分析鉴定各种共混物、复合物和掺有填料的多组份混合物是一种行之有效的方法。     

关于MES性能与应用的疑惑、诀窍和前景

文献报道了MES的许多优点,也提到其性质上可能存在的某些缺点。比如,研究表明纯组分MES的浊点高于其他阴离子表面活性剂,于是怀疑MES的溶解性可能会限制其在冷水中的洗涤。再则,MES的水解稳定性低于其他阴离子表面活性剂,这可能是MES的另一个主要缺点。拟探讨这些问题,并将提出一些证据,以表明MES实际上是一种卓越的表面活性剂,完全可以配方出适用于低温洗涤的洗涤剂产品。介绍了一些采用MES为主要表面活性剂生产洗衣粉和液洗剂的工艺。     

Electro-optical Detection of External Mixtures in Aerosols

A measurement technique was developed that has the capability to resolve externally mixed particles of different refractive indices within the range expected for and observed in atmospheric aerosols. Measurements of laboratory aerosols showed that for a specified geometric size, absorbing particles could be sized either larger or smaller than nonabsorbing particles by an optical particle counter and that the difference was in reasonable agreement with theoretical calculations. Atmospheric measurements showed that there was a range of refractive index present in particles of a specified geometric size from which we conclude that the aerosol was externally mixed chemically with respect to light-absorbing compounds. On some occasions, primarily during times of strong combustion source emissions, the degree of external mixing was large; the percentage of particles in the externally mixed, absorbing subpopulation that we measured ranged from about 20% to 50% of the total at that size. We conclude that the external mixing was largely between soot (or other light absorbing compounds) and inorganic (sulfate and nitrate compounds).     

固体氧化物燃料电池堆的稳定工况特性

以大面积电池和千瓦级电堆为对象,研究了温度、燃料成分、流量等对阳极支撑型电堆性能的影响。结果表明:温度的影响最大,复数阻抗谱中高频弧对应的活化能最高;欧姆阻抗的活化能较低,表明其不全是离子电导的电阻,还包括双极板的表面电阻和可能的接触电阻。利用干氢气燃料测试时,在开路电压附近表现出较大的活化极化,且其活化能很小,表明该活化极化的速率控制步骤并非是电荷转移过程,而是对应某种表面扩散过程。模拟重整气燃料测试过程中活化极化不明显,但开路电压较低,性能比氢气燃料差。随着电堆工作电流的增加,燃料尾气的温度增加,表现出明显的热效应。