89 research outputs found
Jerky motion of dislocations in high-entropy alloys: The linkage between local Peierls stress fluctuations and dislocation mobility
Breakdown of Varvenne scaling in (AuNiPdPt) Cu high-entropy alloys
The compositional dependence of the yield strength Ï has been studied for a series of polycrystalline (AuNiPdPt)Cu alloys by means of compression tests. Ï is found to decrease linearly with increasing Cu concentration. This behaviour is in contradiction to the generalised theory for solid solution strengthening in concentrated solid solutions provided by Varvenne et al. [1]. A breakdown of the scaling behaviour is found as Ïy should be non-linear and slightly increasing when modifying the composition from AuNiPdPt to AuCuNiPdPt
Origins of strength and plasticity in the precious metal based High-Entropy Alloy AuCuNiPdPt
The precious metal based High-Entropy Alloy (HEA) AuCuNiPdPt crystallises in a face-centred cubic structure and is single phase without chemical ordering after homogenisation. However, a decomposition is observed after annealing at intermediate temperatures. This HEA shows extended malleability during cold work up to a logarithmic deformation degree of Ï=2.42. The yield strength ranges from 820âMPa in the recrystallised state to 1170âMPa when strain hardened by cold working with a logarithmic deformation degree of Ï > 0.6. This work hardening behaviour is traced back to a steep increase in dislocation density as well as in deformation twinning occurring at low strain. The microstructure and the mechanical properties of AuCuNiPdPt are assessed in detail by various methods. EBSD and TEM analyses reveal mechanical twinning as an important deformation mechanism. The high strength in the recrystallised state is evaluated and found to originate predominantly upon solid solution strengthening
The origin of jerky dislocation motion in high-entropy alloys
© 2022 Springer Nature Limited. Dislocations in high-entropy alloys encounter pinning during glide resulting in jerky motion. Here the authors demonstrate that the density of high local Peierls force is proportional to the critical stress required for their glide and mobility. Dislocations in single-phase concentrated random alloys, including high-entropy alloys (HEAs), repeatedly encounter pinning during glide, resulting in jerky dislocation motion. While solute-dislocation interaction is well understood in conventional alloys, the origin of individual pinning points in concentrated random alloys is a matter of debate. In this work, we investigate the origin of dislocation pinning in the CoCrFeMnNi HEA. In-situ transmission electron microscopy studies reveal wavy dislocation lines and a jagged glide motion under external loading, even though no segregation or clustering is found around Shockley partial dislocations. Atomistic simulations reproduce the jerky dislocation motion and link the repeated pinning to local fluctuations in the Peierls friction. We demonstrate that the density of high local Peierls friction is proportional to the critical stress required for dislocation glide and the dislocation mobility.11Nsciescopu
Influence of microRNAs from Semen on Bovine Fertility
The objective of this study was to compare the miRNAs within sperm cells of bulls considered to have high and low fertility
Use of Sperm In Vitro Capacitation and Flow Cytometry to Estimate Bull Fertility
Study Description:
Frozen-thawed semen from five bulls previously identified as high (48.1% and 47.7%, bulls A and B, respectively), intermediary (45.5%, bull C) or low (43.1% and 40.7%, bulls D and E, respectively) fertility, based on pregnancy per AI, were evaluated with several laboratory measures. Measures included total motility, sperm plasma membrane integrity (viability), acrosome integrity, reactive oxygen species (ROS), mitochondrial membrane energy potential (mito-potential), zinc signatures (signatures 1 to 4), and CD9 protein populations at pre-wash, post-wash, h 0 (diluted with non-capacitation media), and at 0, 3, 6, and 24 h after dilution with capacitation media and incubation at 37 ÂșC. Data were analyzed using the GLIMMIX procedure of SAS for repeated measures with bull, time, and the interaction as fixed effects. Bull by time interaction was significant (P †0.01) for total motility and viability. There tended (P = 0.06) to be a bull by time interaction for zinc signatures 1 + 2 combined. There was a significant effect of bull (P †0.03) for viability, viable sperm with disrupted acrosome, zinc signatures 1, 2, and 1 + 2, viable CD9- (CD9 negative), and dead CD9+ (CD9 positive). High and intermediary field fertility bulls had greater (P †0.04) percentages of viable sperm, zinc signature 2, and zinc signature 1 + 2 compared to low fertility bulls. High and intermediary fertility bulls had decreased (P †0.05) percentage of dead CD9+ compared to low fertility bulls. There was or tended to be a positive correlation between pregnancy per AI and viability (P = 0.10; r = 0.81), zinc signature 2 (P = 0.04; r = 0.89), and zinc signature 1 + 2 (P = 0.10; r = 0.80)
Simultaneous measurement of muon neutrino charged-current single production in CH, C, HO, Fe, and Pb targets in MINERvA
Neutrino-induced charged-current single production in the
resonance region is of considerable interest to
accelerator-based neutrino oscillation experiments. In this work, high
statistics differential cross sections are reported for the semi-exclusive
reaction nucleon(s) on scintillator, carbon,
water, iron, and lead targets recorded by MINERvA using a wide-band
beam with \left \approx 6~GeV. Suppression of the cross
section at low and enhancement of low are observed in both light
and heavy nuclear targets compared to phenomenological models used in current
neutrino interaction generators. The cross-section ratios for iron and lead
compared to CH across the kinematic variables probed are 0.8 and 0.5
respectively, a scaling which is also not predicted by current generators.Comment: 6 pages, 6 figures, 117 pages of supplementary material; submitted to
Physical Review Letter
SNAP-tagged Chikungunya Virus Replicons Improve Visualisation of Non-Structural Protein 3 by Fluorescence Microscopy
Chikungunya virus (CHIKV), a mosquito-borne alphavirus, causes febrile disease, muscle and joint pain, which can become chronic in some individuals. The non-structural protein 3 (nsP3) plays essential roles during infection, but a complete understanding of its function is lacking. Here we used a microscopy-based approach to image CHIKV nsP3 inside human cells. The SNAP system consists of a self-labelling enzyme tag, which catalyses the covalent linking of exogenously supplemented synthetic ligands. Genetic insertion of this tag resulted in viable replicons and specific labelling while preserving the effect of nsP3 on stress granule responses and co-localisation with GTPase Activating Protein (SH3 domain) Binding Proteins (G3BPs). With sub-diffraction, three-dimensional, optical imaging, we visualised nsP3-positive structures with variable density and morphology, including high-density rod-like structures, large spherical granules, and small, low-density structures. Next, we confirmed the utility of the SNAP tag for studying protein turnover by pulse-chase labelling. We also revealed an association of nsP3 with cellular lipid droplets and examined the spatial relationships between nsP3 and the non-structural protein 1 (nsP1). Together, our study provides a sensitive, specific, and versatile system for fundamental research into the individual functions of a viral non-structural protein during infection with a medically important arthropod-borne virus (arbovirus)
Effect of the ovulatory follicle diameter and progesterone concentration on the pregnancy rate of fixed-time inseminated lactating beef cows
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