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.     

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.     

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     

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.     

ACE2, the Receptor that Enables Infection by SARS-CoV-2: Biochemistry,Structure, Allostery and Evaluation of the Potential Development of ACE2 Modulators

Angiotensin converting enzyme 2 (ACE2) is the human receptor that interacts with the spike protein of coronaviruses, including the one that produced the 2020 coronavirus pandemic (COVID-19). Thus, ACE2 is a potential target for drugs that disrupt the interaction of human cells with SARS-CoV-2 to abolish infection. There is also interest in drugs that inhibit or activate ACE2, that is, for cardiovascular disorders or colitis. Compounds binding at alternative sites could allosterically affect the interaction with the spike protein. Herein, we review biochemical, chemical biology, and structural information on ACE2, including the recent cryoEM structures of full-length ACE2. We conclude that ACE2 is very dynamic and that allosteric drugs could be developed to target ACE2. At the time of the 2020 pandemic, we suggest that available ACE2 inhibitors or activators in advanced development should be tested for their ability to allosterically displace the interaction between ACE2 and the spike protein.     

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。     

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.     

Miniemulsions using static mixers: Part 2. Co‐emulsification and composite materials using SMX static mixers

A 50:50 mixture of methylmethacrylate (MMA) and butyl acrylate was emulsified, then polymerised using different static mixers. It was shown that the emulsification behaviour was very different from that observed for MMA alone under similar conditions. It was shown that the hydrophobicity of the monomers had a strong influence on the droplet size and stability. It was also shown that the amount of work done on the emulsion is important for obtaining polymerisable droplets, and that monomer systems that are difficult to miniemulsify with a low energy system can in fact be made to form stable emulsions simply by changing the emulsification conditions. Finally, it was shown that when the miniemulsification conditions are correctly chosen, it is possible to generate miniemulsion dispersions containing silica that can be successfully polymerised to produce silica/polyacrylic nanocomposites.     

旋转真空浸渍法制备NiO/MgO-γ-Al_2O_3催化剂用于CO_2/CH_4重整研究

采用旋转真空浸渍法和等体积浸渍法分别制备了NiO/MgO-γ-Al2O3催化剂RVIC和WIC。N2吸附实验表明,RVIC催化剂具有更大的比表面积。XRD结果表明,RVIC和WIC中的镍物种存在方式均为尖晶石NiAl2O4;TPR结果表明,两试样均在800℃处出现尖晶石NiAl2O4的还原峰,且RVIC的还原峰面积比WIC的大13%。还原后的XRD结果表明,RVIC的Ni晶粒尺寸仅为5.8 nm,小于WIC的7.3 nm。H2-TPR结果显示,试样RVIC活性组分Ni的分散度为0.491,大于WIC(0.116)。活性评价结果显示,RVIC的CH4与CO2最终转化率分别为98%与77%,远远高于WIC(CH4与CO2最终转化率分别为55%和40%)。240 h寿命实验结果显示,RVIC的CH4转化率高达100%,CO2稳定转化率超过70%。     

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.     

Phenolics in ecological interactions: The importance of oxidation

The ecological activities of plant phenolics are diverse and highly variable. Although some variation is attributable to differences in concentration, structure, and evolutionary history of association with target organisms, much of it is unexplained, making it difficult to predict when and where phenolics will be active. I suggest that our understanding is limited by a failure to appreciate the importance of oxidative activation and the conditions that influence it. I summarize examples of oxidative activation of phenolics in ecological interactions, and argue that physicochemical conditions of the environment that control phenolic oxidation generate variation in ecological activity. Finally, I suggest that measurements of oxidative conditions can improve our predictions of phenolic activity and that experiments must be designed with conditions appropriate to the biochemical mode of phenolic action.     

脂肪酰胺丙基氧化胺的性能及应用研究

测试了不同碳链的脂肪酰胺丙基氧化胺的去污、润湿、泡沫和乳化性能,考察了其在配方中的增稠及耐寒性能,并与椰油基烷醇酰胺对比。实验结果表明,不同碳链的脂肪酰胺丙基氧化胺的去污力和泡沫力均好于椰油基烷醇酰胺,润湿力则不如椰油基烷醇酰胺,前者在配方中的增稠性能均优于后者,耐寒性能方面,月桂基酰胺丙基氧化胺（LAO）、椰油酰胺丙基氧化胺（CAO）与椰油烷醇酰胺（6501）相近,高碳酰胺丙基氧化胺则要差于椰油基烷醇酰胺。     

国产集成橡胶SIBR基本性能的研究

研究了国产集成橡胶(SIBR)的基本性能,结果表明:SIBR与乳聚丁苯橡胶物理机械性能相当;其动态力学性能与通用乳聚丁苯橡胶相比,SIBR在0℃具有更高的tanδ值,在60℃具有更低的tanδ值,说明SIBR具有高抗湿滑性和低滚动阻力;压缩疲劳温升实验结果表明SIBR比丁苯橡胶压缩疲劳温升低,压缩永久变形率更小。实验证明SIBR是一种良好的轮胎胎面用橡胶。     

Structure and properties of bio-based polyurethane coatings for controlled-release fertilizer

Two kinds of bio-based polyurethane coatings for controlled-release urea were prepared by in-situ polymerization used castor oil and liquefied starch as raw materials, respectively. Scanning electron microscopy (SEM) showed that the section morphology of castor oil based polyurethane (Castor-PU) coating was uniform and dense, and that of liquefied starch based polyurethane (Starch-PU) coating had certain proportion of microporous. Infrared spectroscopy (IR) showed that the two coatings had typical urethane characteristic structure, but the difference was that the Starch-PU had obvious unreacted isocyanate structure. Differential scanning calorimetry (DSC) showed that the glass transition temperature of the two coatings was around 58°C, but the Castor-PU had a crystallization domain with obvious crystallization melting peak at 130°C. Thermogravimetric analysis (TG) showed that the thermal stability of Castor-PU was significantly higher than that of Starch-PU. The controlled-release property test showed that when the coating ratio was 2.8%, the nutrient release longevity of urea coated with Castor-PU was 49 days and that of urea coated with Starch-PU was 14 days. The reasons for the poor controlled-release performance of Starch-PU were analyzed, which probably caused by concentrated sulfuric acid and hydrophilic dispersant added in the liquefied starch.     

几种天然纤维素纤维的物理结构研究

对竹纤维等几种天然纤维素纤维的物理结构进行了系统的比较研究。实验结果表明:竹纤维聚合度远高于粘胶、稍低于苎麻;结晶度高、取向度高,属于大分子排列整齐、紧密型超分子结构,接近于苎麻纤维;在形态结构上,横截面为腰圆形,有中腔,壁上有裂纹,截面有孔隙,TEM结果表明,次生层为单层次结构,与苎麻相仿。总之,竹纤维从微观的大分子链结构到聚集态结构,到宏观的纤维形态结构,各种物理指标特征均表明其与苎麻纤维有着非常的相似性。     

Antioxidants and the autoxidation of fats

Summary Experiments on the oxidation of purified methyl oleate support the view that its induction period, and probably that of natural oils, is due to the presence of inhibitors and that purified unsaturated compounds have no induction period, other than the time required for gaseous oxygen to diffuse into the liquid. Experiments with antioxidants indicate that phenolic inhibitors and inhibitols cause no change subsequent to the end of the induction period, that they exert their effect solely by inhibiting the formation of the initial active moloxide, and that they are entirely destroyed before the start of rapid oxidation which characterizes the end of the induction period. The mode of action of several different pro-oxidants is analyzed. Perbenzoic acid, and presumably other peracids, and copper oleate decrease the induction period by virtue of their destruction of natural inhibitors.     

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.     

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.     

Effect of Surface Conditions on Room-Temperature Ductility of Ionic Crystals

With the progress on dislocation theories and a better understanding of flow phenomena, it was predicted that a class of materials normally considered to be brittle, namely, ionic solids having cubic crystal structures, would possess a degree of ductility. Experimental results on a number of ionic materials indicate that face-centered cubic and body-centered cubic ionic materials can exhibit a considerable amount of ductility under controlled conditions. It was found that these materials are inherently ductile rather than brittle and that there appear to be two factors, a surface reaction with components of the air and impurity concentration, that exert control over the ductility. The examination of the air embrittlement indicated that oxygen and nitrogen are the cause of decreased ductility in water-soluble salts such as KC1 and KBr. The effect on the surface can be inhibited by surface treatment or by immersion in oil. Other materials such as MgO and LiF do not seem to exhibit a surface embrittlement. MgO does, however, show a time-dependent ductility that is attributed to the presence of impurities.