Electrocatalytic Mapping of Metal Fatigue with Persistent Slip Bands.

Metal fatigue, characterized by the accumulation of dislocation defects, is a prevalent failure mode in structural materials. Nondestructive early-stage detection of metal fatigue is extremely important to prevent disastrous events and protect human life. However, the lack of a precise quantitative method to visualize fatigue with spatiotemporal resolution poses a significant obstacle to timely detection.

Strain-Induced Nonlinear Frictional Behavior of Graphene Nanowall Films.

Graphene nanowall (GNW) films, a representation of three-dimensional (3D) carbon nanomaterial films, are emerging as promising candidates for applications in electric devices and composites, on account of their 3D structures and exceptional properties of graphene sheets. However, the frictional responses of GNW films, which exhibit significant influence on their performances, have seldom been reported. Herein, we reported a growth process of a GNW film by the chemical vapor deposition method and studied the frictional behavior of the GNW film for the first time.

Microscopic Mechanisms Behind the High Friction and Failure Initiation of Graphene Wrinkles.

Wrinkling occurs on the surfaces of large-area graphene ubiquitously. Despite that the wrinkled structures are found to degrade the lubricous property, the behind mechanisms remain less understood. Here, atomic force microscopy is adopted to characterize the friction and wear properties of graphene wrinkles (GWs) with different heights by nanoscratch tests.

Redox-Sensitive Ultrashort Peptide Hydrogel with Tunable Mechanical Properties for Anti-Tumor Drug Delivery.

In this study, we report a new ultrashort peptide (LOC), which forms a redox-sensitive hydrogel after cross-linking with the mild oxidant H₂ O₂ and used it for tumor-targeted delivery of doxorubicin hydrochloride (DOX). LOC gelled within a few minutes in low-concentration H₂ O₂ solution. The concentration of H₂ O₂ significantly altered the gelation time and mechanical properties of the hydrogel.

Injectable pH and redox dual responsive hydrogels based on self-assembled peptides for anti-tumor drug delivery.

Traditional anti-tumor drugs still have some shortcomings, such as low solubility, poor selectivity and poor bioavailability, which decrease their anti-tumor efficacy and aggravate systemic toxicity and side effects. In this paper, pH/redox dual responsive IC1-R peptide hydrogels were designed as drug delivery materials for the anti-tumor drug paclitaxel (PTX). The physical and chemical properties of drug-loaded IC1-R peptide hydrogels were characterized by pH/redox sensitivity, drug release, physical description, encapsulation rate, circular dichroism, electron transmission microscopy, and rheological tests.

Double-Vacancy Controlled Friction on Graphene: The Enhancement of Atomic Pinning.

The vacancy-enhanced contact friction of graphene is mainly attributed to the vacancy-enhanced out-of-plane deformation flexibility of the graphene and the climbing of the tip out of the vacancy trap (which actually acts as a step edge). However, this mechanism does not apply for explaining the enhanced friction caused by small-sized vacancies that are unable to accommodate the tip, such as single vacancy and double vacancies, which also commonly exist in the graphene. In the present study, by performing a set of classic molecular dynamics simulations, we demonstrated that the double-vacancy defect in graphene substantially enhanced the contact friction when the tip slides over it and the pinning effect of the reconstructed lattice of the double-vacancy defect with atoms at the bottom of the tip dominated such an influence.

Effect of particle size of hydroxyapatite nanoparticles on its biocompatibility.

Nano-particulate biomaterials have been used in clinical diagnosis and treatment, as drug carrier or in cosmetics because of their excellent performance properties. The toxicity and biocompatibility of nanoparticles (NPs), however, are always a focused concern for a doctor or a scientist. At present, there is almost no systemic evaluation standard or testing methods of safety for nanoparticles.