铝合金薄板尖边缘缺口试样的机械加工方法及缺口敏感性测试

介绍高强度铝合金薄板的尖边缘缺口拉伸试样的机械加工方法，用该方法制备的仿美７０７５、美制７０７５、国产ＬＣ４、ＬＣ９、ＬＹ１２、ＬＢ７３３等６种铝合金１６种热处理状态下的ＥＮ试样，其内率半径Ｒ满足了ＡＳＴＭＥ３３８－６８标准方法中Ｒｍａｘ０．０１８毫米的要求，并且达到Ｒ＜０．０１０毫米的特高精度。同时，还对仿美７０７５、美制７０７５、国产ＬＣ４的６种热处理状态下的缺口敏感性和宏观断口、以及选择仿美７０７５、ＬＹ１２对扫描断口形态进行了研究。     

合金元素对Fe-Al-Cu合金的组织与性能的影响

研究了不同含量的钛、锰、硼及其交互作用对70.8Fe18.7Cu10.5Al(w/%)合金铸态组织与性能的影响。结果表明:合金由铁固溶体、铜固溶体及弥散分布于铁固溶体中的析出相组成。钛、硼的加入可细化结晶组织并提高合金的抗拉强度;加入适量的钛、锰、硼可使合金获得较好的综合力学性能。     

Strengthening of AISI 2205 duplex stainless steel by strain ageing

In this study, static strain ageing behavior of commercially available and solution heat treated duplex stainless steel was investigated and the effect of static strain ageing on the mechanical properties was also determined in detail. Some of as-received duplex stainless steel test specimens were pre-strained in tension by 5% and then aged at 100 °C, 200 °C, 300 °C, 400 °C, 500 °C and 600 °C for 30 min in furnace. Some of duplex stainless steel test specimens were solution heat treated at 1050 °C for 30 min, water quenched and then pre-strained for 5% in tension shortly after the solution heat treatment.In order to identify the effect of static strain ageing on the mechanical properties, the tensile strength, the change in the strength due to ageing (ΔY), elongation fracture and hardness were determined. The test results showed that the mechanical properties were affected by static strain ageing mechanism which was applied at different temperatures for same time interval.     

Insights into the cross-amyloid aggregation of Aβ40 and its N-terminal truncated peptide Aβ11-40 affected by epigallocatechin gallate

Inhibition of protein misfolding and aggregation is a great challenge in the field of biochemical and biopharmaceutical engineering. Alzheimer's disease (AD) is a protein-misfolding disease, and the interactions between 40-amino-acid-residue β-amyloid peptide (Aβ₄₀) and its N-terminal truncated peptide Aβ_11-40 demonstrate that Aβ_11-40 may play an important role in the pathological process of AD. However, the effect of inhibitors on Aβ_11-40 aggregation and on the cross-amyloid aggregation (co-assembly) between Aβ₄₀ and Aβ_11-40 has never been studied. Herein, coaggregation and seeding interactions between Aβ₄₀ and Aβ_11-40 as well as the effect of epigallocatechin gallate (EGCG), a small molecule inhibitor, on the cross-amyloid aggregation have been investigated by extensive analyses. It is found that Aβ_11-40 participates in the aggregation of Aβ₄₀ and leads to the formation of coaggregates that contain less β-sheet structures than pure Aβ₄₀ aggregates. The aggregation kinetics along with morphologies and secondary structures of the coaggregates are also significantly affected by the Aβ₄₀/Aβ_11-40 ratio. EGCG accelerates the nucleation of Aβ₄₀ but retards that of Aβ_11-40 by affecting their elongation and secondary nucleation processes in solution and on solid surfaces. Meanwhile, EGCG makes the conformations of the seeding-induced Aβ aggregates more compact, especially for the homologous seedings. Isothermal titration calorimetry measurement indicates that hydrophobic interactions mainly contribute to the inhibition of the two Aβ isoforms by EGCG. The findings of this research have provided new insights into Aβ aggregation and the effect of an important inhibitor and the results would benefit in the development of potent inhibitors against co-assembly of different amyloid proteins.     

牛奶蛋白纤维不锈钢长丝包芯纱的研制

分析用于纺织品中的不锈钢长丝的表面形态及力学性能。介绍了不锈钢丝牛奶蛋白纤维包芯纱的纺纱装置、工艺流程及原理。并对5种不同特数、不同不锈钢丝含量包芯纱力学性能、纵向形态及毛羽指数等进行对比分析。结果表明:将不锈钢长丝与牛奶蛋白纤维做成包芯纱用于设计电磁屏蔽面料是可行的。既有牛奶蛋白纤维的舒适性,又具有防电磁辐射的功能。与纯牛奶蛋白纤维纱比较,其断裂强度随不锈钢丝含量增大而减小;断裂伸长在不锈钢丝含量30%以内时,降低不明显,30%以上时明显减小。成纱2 mm、3 mm毛羽数高于纯牛奶蛋白纤维纱。     

Stretching, shearing and solidification

It has been suggested that isothermal flow-induced crystallization is linked jointly to shear strain and strain-rate. By combining continuum mechanics methods and experimental results, an invariant general strain-rate-strain model for some crystallizing polymers, applicable to all flows, is constructed. Examples show the great differences of response in shear and elongation; at a given rate elongation is the more powerful promoter of crystallinity.     

Matched asymptotic solution for flow in a semi-hyperbolic die

A semi-hyperbolic converging geometry finds application as an inexpensive elongation rheometer under certain flow conditions. We provide a matched asymptotic solution for the flow of a Newtonian fluid under no-slip boundary conditions. The predicted velocity and pressure profiles agree nearly quantitatively with CFD simulated values. Our theoretical approach has certain advantages over the known similarity solution proposed by James (1991. A.I.Ch.E. Journal 37, 59-64).     

两种牦牛绒集聚纱性能的对比分析

探讨两种集聚纺装置纺制牦牛绒集聚纱和赛络集聚纱的成纱性能。分别采用网格圈式和空心罗拉式集聚纺装置纺制牦牛绒20.8tex集聚纱和16.7tex赛络集聚纱,并进行了性能对比测试。结果表明:纺制20.8tex牦牛绒集聚纱,两者毛羽水平相当,空心罗拉式集聚纺所纺纱强伸性能显著提高,条干均匀度略好;纺制16.7tex牦牛绒赛络集聚纱,空心罗拉式所纺纱强伸性显著提高,毛羽明显减少,条干均匀度显著改善。认为:实际生产中,可根据纺纱品种和质量要求,合理选择集聚纺装置和赛络纺工艺,能够纺制出性能较好,质量满足要求的牦牛绒纱。