Origin of Deformation Twinning in bcc Tungsten and Molybdenum.

Twinning is profuse in bcc transition metals (TMs) except bulk W and Mo. However, W and Mo nanocrystals surprisingly exhibit twinning during room temperature compression, which is completely unexpected as established nucleation mechanisms are not viable in them. Here, we reveal the physical origin of deformation twinning in W and Mo.

Myricitrin EGCG in the Treatment of Obesity: Target Mining and Molecular Mechanism Exploring based on Network Pharmacology.

Background: Myricitrin is a flavonol glycoside possessing beneficial effects on obesity, a rising global health issue that affects millions of people worldwide. However, the involving target and mechanism remain unclear.

Objective: In the present study, the anti-obesity targets and molecular mechanisms of Myricitrin, along with another flavanol Epigallocatechin gallate (EGCG), were explored through network pharmacology, bioinformatics, and molecular docking.

Atomic-Scale Observation of 5-Fold Twin Formation in Nanoscale Crystal under Mechanical Loading.

A 5-fold twin is usually observed in nanostructured metals after mechanical tests and/or annealing treatment. However, the formation mechanism of a 5-fold twin has not been fully elaborated, due to the lack of direct time-resolved atomic-scale observation. Here, by using nanomechanical testing combined with atomistic simulations, we show that sequential twinning slip in varying slip systems and decomposition of high-energy grain boundaries account for the 5-fold twin formation in a nanoscale gold single crystal under bending as well as the reversible formation and dissolution of a 5-fold twin in a nanocrystal with a preexisting twin under tension and shearing.

Atomic-scale observation of dynamic grain boundary structural transformation during shear-mediated migration.

Grain boundary (GB) structural change is commonly observed during and after stress-driven GB migration in nanocrystalline materials, but its exact atomic scale transformation has not been explored experimentally. Here, using in situ high-resolution transmission electron microscopy combined with molecular dynamics simulations, we observed the dynamic GB structural transformation stemming from reversible facet transformation and GB dissociation during the shear-mediated migration of faceted GBs in gold nanocrystals. A reversible transformation was found to occur between (002)/(111) and Σ11(113) GB facets, accomplished by the coalescence and detachment of [Formula: see text]-type GB steps or disconnections that mediated the GB migration.

Ultimate Strength of Nanotwinned Face-Centered Cubic Metals.

In this work, we present a theoretical model to predict the ultimate strength of nanotwinned face-centered cubic (fcc) metals based on the activation energy for phase transformation (i.e., between the matrix and the twinned counterpart) mediated by the migration of {112}-type step on Σ3(111) twin boundaries.

In situ atomistic observation of disconnection-mediated grain boundary migration.

Shear-coupled grain boundary (GB) migration is of general significance in the deformation of nanocrystalline and polycrystalline materials, but comprehensive understanding of the migration mechanism at the atomic scale remains largely lacking. Here, we systematically investigate the atomistic migration of Σ11(113) coherent GBs in gold bicrystals using a state-of-art in situ shear testing technique combined with molecular dynamic simulations. We show that shear-coupled GB migration can be realised by the lateral motion of layer-by-layer nucleated GB disconnections, where both single-layer and double-layer disconnections have important contributions to the GB migration through their frequent composition and decomposition.

Egg Albumen as a Fast and Strong Medical Adhesive Glue.

Sutures penetrate tissues to close wounds. This process leads to inflammatory responses, prolongs healing time, and increases operation complexity. It becomes even worse when sutures are applied to stress-sensitive and fragile tissues.

Disclination mediated dynamic recrystallization in metals at low temperature.

Recrystallization is one of the most important physical phenomena in condensed matter that has been utilized for materials processing for thousands of years in human history. It is generally believed that recrystallization is thermally activated and a minimum temperature must be achieved for the necessary atomic mechanisms to occur. Here, using atomistic simulations, we report a new mechanism of dynamic recrystallization that can operate at temperature as low as T = 10 K in metals during deformation.

Strong Hall-Petch Type Behavior in the Elastic Strain Limit of Nanotwinned Gold Nanowires.

Pushing the limits of elastic deformation in nanowires subjected to stress is important for the design and performance of nanoscale devices from elastic strain engineering. Particularly, introducing nanoscale twins has proved effective in rising the tensile strength of metals. However, attaining ideal elastic strains in nanotwinned materials remains challenging, because nonuniform twin sizes locally affect the yielding behavior.

Atomistic simulation of slow grain boundary motion.

Existing atomistic simulation techniques to study grain boundary motion are usually limited to either high velocities or temperatures and are difficult to compare to realistic experimental conditions. Here we introduce an adapted simulation method that can access boundary velocities in the experimental range and extract mobilities in the zero driving force limit at temperatures as low as ∼0.2T(m) (T(m) is the melting point).

18F-FDG PET/CT-related metabolic parameters and their value in early prediction of chemotherapy response in a VX2 tumor model.

Objective: This study acquired fluorine-18-deoxyglucose (FDG) kinetic parameters prior and subsequent to cisplatin chemotherapy so as to define the optimal parameters for early prediction of chemotherapy response.

Methods: A total of 12 non-tumor-bearing rabbits were used to obtain noninvasive input function, five VX2 tumor-bearing rabbits were used for validation and 32 tumor-bearing rabbits underwent 4 mg kg(-1) cisplatin chemotherapy. Dynamic FDG PET/CT was performed at pretherapy, Day 0, Day 1, Day 7 and Day 14 after cisplatin administration.

Near-ideal strength in gold nanowires achieved through microstructural design.

The ideal strength of crystalline solids refers to the stress at elastic instability of a hypothetical defect-free crystal with infinite dimensions subjected to an increasing load. Experimentally observed metallic wires of a few tens of nanometers in diameter usually yield far before the ideal strength, because different types of surface or structural defects, such as surface inhomogeneities or grain boundaries, act to decrease the stress required for dislocation nucleation and irreversible deformation. In this study, however, we report on atomistic simulations of near-ideal strength in pure Au nanowires with complex faceted structures related to realistic nanowires.

Enabling ultrahigh plastic flow and work hardening in twinned gold nanowires.

By using molecular dynamics simulations, we show that significant strain hardening and ultrahigh flow stresses are enabled in gold nanowires containing coherent (111) growth twins when balancing nanowire diameter and twin boundary spacing at the nanoscale. A fundamental transition in mechanical behavior occurs when the ratio of diameter to twin boundary spacing is larger than 2.14.