Formation of Amyloid-Like Fibrils by Y-Box Binding Protein 1 (YB-1) Is Mediated by Its Cold Shock Domain and Modulated by Disordered Terminal Domains

YB-1, a multifunctional DNA- and RNA-binding nucleocytoplasmic protein, is involved in the majority of DNA- and mRNA-dependent events in the cell. It consists of three structurally different domains: its central cold shock domain has the structure of a β-barrel, while the flanking domains are predicted to be intrinsically disordered. Recently, we showed that YB-1 is capable of forming elongated fibrils under high ionic strength conditions. Here we report that it is the cold shock domain that is responsible for formation of YB-1 fibrils, while the terminal domains differentially modulate this process depending on salt conditions. We demonstrate that YB-1 fibrils have amyloid-like features, including affinity for specific dyes and a typical X-ray diffraction pattern, and that in contrast to most of amyloids, they disassemble under nearly physiological conditions

Microstructural Developments Through Marforming in a Ni-Ti-Fe Shape Memory Alloy

A hot-rolled Ni-Ti-Fe alloy was subjected to marforming: approximately 8 pct reduction (in thickness) in the martensite phase by laboratory rolling. Before the next marforming step, the sample was annealed to bring back calorimetric signatures of reversible austenite-martensite phase transformation. Significant differences in microstructure could be achieved by combinations of marforming and annealing. Such differences, on the other hand, originated from the marformed microstructure: two distinct regions of remarkably different substructures. The difference was mainly through the relative presence of defects: micro-twins and dislocations. The regions of lower defect densities got textured gradually, with marforming steps, to gamma (ND//aOE (c) 111 >) fiber. The regions with high defect densities, on the other hand, provided non-gamma fine clustered grains after annealing. Though debates may continue on the exact nature and origin of micro-twins, the present study brought out their dominant role in determining almost all aspects of microstructural developments

Development of Texture and Microstructure During Cold Rolling and Annealing of a Fe-Based Shape Memory Alloy

Texture evolution and microstructural changes during cold rolling and annealing of Fe-14Mn-6Si-9Cr-5Ni shape memory alloy have been investigated. The starting solution-annealed material has a nearly random texture with microstructure composed of equiaxed austenite grains with epsilon martensite plates inside. Cold rolling induces a strong alloy type texture with Brass {011}aOE (c) 211 > and Goss {011}aOE (c) 100 > as major components. Annealing of the cold-deformed material produces a nearly random texture. The microstructural investigation reveals that with increase in cold deformation, the amount of stress-induced epsilon and alpha' martensite volumes increase. The electron back-scattered diffraction (EBSD) phase mapping shows that reversion of the epsilon martensite begins only after recrystallization sets in at a temperature of 1073 K

Effect of Pre-straining on the Shape Recovery of Fe-Mn-Si-Cr-Ni Shape Memory Alloys

The effect of pre-straining on the shape recovery behavior of Fe-14Mn-6Si-9Cr-5Ni (wt pct) shape memory alloy (SMA) has been studied. The shape recovery associated with the reverse epsilon martensitic transformation, i.e., epsilon -> gamma, was characterized by dilatometry using specimens which were pre-strained to different extent (0 to 14 pct). Dilatometric studies revealed that in Fe-Mn-Si-Cr-Ni SMA, the shape recovery takes place in two stages: (i) in the first stage, the unpinned fraction of stress-induced epsilon martensite reverts back to parent phase gamma in the temperature regime of 353 K to 653 K (80 A degrees C to 380 A degrees C) and (ii) in the second stage the remaining "pinned" epsilon martensite is unpinned by the decomposition of deformation-induced alpha' martensite in the temperature range of 743 K to 893 K (470 A degrees C to 620 A degrees C). The amount of recovery in the first stage decreases with pre-strain, whereas it increases in the second stage. The epsilon -> gamma transformation finish temperature, A (f), increases with increase in pre-strain amount, though the reverse transformation start temperature, A (S), remains unaffected. Microstructural characterization revealed that the amount of deformation-induced alpha' martensite depends on the mode of straining and the crystallographic texture of the starting material. The reversion of alpha' martensite is seen to occur by the precipitation of Fe5Ni3Si2-type intermetallic pi-phase within these plates

Origin of Microstructural Irreversibility in Ni-Ti Based Shape Memory Alloys during Thermal Cycling

Different microstructures of Ni-Ti- and Ni-Ti-Fe-based shape memory alloys were subjected to thermal cycling: dipping in liquid nitrogen, for approximately 5 minutes, and then bringing it back to room temperature or austenite (cubic: B2) martensite (monoclinic: B19') reversible solid-state phase transformation. Direct electron backscattered diffraction (EBSD) observations could bring out aspects of microstructural irreversibilities: namely, changes in grain size, mis-orientation buildup, and presence of retained martensite. The average changes in grain size (Delta d) differed by almost 2 to 4 times between different microstructures. The highest Delta d was typically observed in structures having maximum clustering of fine (d orientation relationship between austenite and martensite phases, was proposed to address the observed patterns of microstructural irreversibility