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[en] In combining biomechanical investigations with microanatomical studies, the authors have found new evidence suggesting a mechanobiological link between the altered microstructural response of degenerate cartilage to load, and the way in which structural changes develop in the early osteoarthritic joint. This paper presents the data and background for a new hypothesis exploring the initiation and progression of mechanically-driven osteoarthritic processes.
[en] The purpose of the current work is to analyse the effect of tilt angle and tool hardness on mechanical and microstructural characteristics of FSWed Al-Mg4.2 joints. The joints were fabricated varying the tilt angle and tool hardness at six different levels each, keeping other FSW parameters constant. Microstructure, macrostructure, strength and hardness characteristic of the welds has been sifted in order to understand the sensitivity of studied input variables on the joints quality. The outcome of the present investigation clearly indicates that the tilt angle and tool hardness notably affects the performance parameters of the FSWed joints. The paper suggests that 1°−3° tilt angle and 40–50 HRC tool hardness produces sound quality joints. The present work dredges a novel look on FSWed Al-Mg4.2 joints by dint of relating the macrostructure, microstructure and fractographs with the plasticized material movement in the process. (paper)
[en] Full text:The copolymerization reaction of ρ-(substituted) cyclopropyl styrene's with styrene has been studied. An influence of substituent's on reactivity of ρ-(substituted) cyclopropyl styrene's has been investigated. The copolymerization constant values and Q-e parameters of Alfrey-Praice scheme have been calculated. The parameters of microstructure of copolymers have been determined
[en] We summarize recent advances in modeling of solidification microstructures using computational methods that bridge atomistic to continuum scales. We first discuss progress in atomistic modeling of equilibrium and non-equilibrium solid-liquid interface properties influencing microstructure formation, as well as interface coalescence phenomena influencing the late stages of solidification. The latter is relevant in the context of hot tearing reviewed in the article by M. Rappaz in this issue. We then discuss progress to model microstructures on a continuum scale using phase-field methods. We focus on selected examples in which modeling of 3D cellular and dendritic microstructures has been directly linked to experimental observations. Finally, we discuss a recently introduced coarse-grained dendritic needle network approach to simulate the formation of well-developed dendritic microstructures. The approach reliably bridges the well-separated scales traditionally simulated by phase-field and grain structure models, hence opening new avenues for quantitative modeling of complex intra- and inter-grain dynamical interactions on a grain scale
[en] The high alkaline property in the concrete pore solution protects the embedded steel in concrete from corrosion due to aggressive ions attack. However, a continuous supply of those ions, in particular, chlorides altogether with a pH fall in electrochemical reaction on the steel surface eventually depassivate the steel to corrode. To mitigate chloride-induced corrosion in concrete structures, finely grained mineral admixtures, for example, pulverized fuel ash (PFA), ground granulated blast furnace slag (GGBS) and silica fume (SF) have been often advised to replace ordinary Portland cement (OPC) partially as binder. A consistent assessment of those partial replacements has been rarely performed with respect to the resistance of each binder to corrosion, although the studies for each binder were extensively looked into in a way of measuring the corrosion rate, influence of microstructure or chemistry of chlorides ions with cement hydrations. The paper studies the behavior of steel corrosion, chloride transport, pore structure and buffering capacity of those cementitious binders. The corrosion rate of steel in mortars of OPC, 30% PFA, 60% GGBS and 10% SF respectively, with chloride in cast ranging from 0.0 to 3.0% by weight of binder was measured at 7, 28 and 150 days to determine the chloride threshold level and the rate of corrosion propagation, using the anodic polarization technique. Mercury intrusion porosimetry was also applied to cement pastes of each binder at 7 and 28 days to ensure the development of pore structure. Finally, the release rate of bound chlorides (I.e. buffering capacity) was measured at 150 days. The chloride threshold level was determined assuming that the corrosion rate is beyond 1-2 mA/m3 at corrosion and the order of the level was OPC > 10% SF > 60% GGBS > 30% PFA. Mercury intrusion porosimetry showed that 10% SF paste produced the most dense pore structure, followed by 60% GGBS, 30% PFA and OPC pastes, respectively. It was found that OPC itself is beneficial in resisting to corrosion initiation, but use of pozzolanic materials as binders shows more resistance to chloride transport into concrete, thus delay the onset of corrosion