Tough, Slippery, and Low-Permeability Multilayer Hydrogels Modified by Anisotropic Fiber Membrane for Soft Tissue Replacement.

Hydrogels with sustained lubrication, high load-bearing capacity, and wear resistance are essential for applications in soft tissue replacements and soft material devices. Traditional tough or lubricious hydrogels fail to balance the lubrication and load-bearing functions. Inspired by the gradient-ordered multilayer structures of natural tissues (such as cartilage and ligaments), a tough, smooth, low-permeability, and low-friction anisotropic layered electrospun fiber membrane-reinforced hydrogel was developed using electrospinning and annealing recrystallization.

Construction and Properties of High-Toughness Soft-Soft Interfaces Based on the Adhesion of Natural Polyphenols.

Artificial joint replacement is the most effective way to treat osteoarthritis. However, these artificial joints are too stiff with high interfacial contact stress and poor surface lubrication, resulting in stress shielding and severe wear and tear lead to an extremely high failure rate. At present, hydrogels are considered the most promising substitute for artificial joint prostheses owing to their good biocompatibility, adjustable mechanical properties, and excellent flexibility.

Atomistic Insights into Interfacial Optimization Mechanism for Achieving Ultralow-Friction Amorphous Carbon Films under Solid-Liquid Composite Conditions.

The combination of fluid lubricants and textured amorphous carbon (a-C) can provide an ultralow friction state, which can improve the reliability and service life of dynamic machinery. However, the coupling effects of the contact pressure and oil content on the friction-reducing efficiency is still lack of study, and the corresponding friction mechanism is also not fully understood, which cannot be achieved by experiment due to the limitation of in situ characterization. In this study, using the reactive molecular dynamics simulation, the insight into the evolution of interfacial structures induced by both contact pressures and oil contents on a-C surface was systematically investigated to explore the fundamental mechanism.

Special Issue: Friction, Corrosion and Protection of Material Surfaces.

The current Special Issue, entitled "Friction, Corrosion and Protection of Material Surfaces", aims to discuss the state-of-the-art research progress regarding the friction and corrosion behaviors of new materials and advanced protective materials or technologies, with a special focus on the understanding of underlying friction and corrosion mechanisms and modification approaches of material surfaces against friction and corrosion in order to guide the design and preparation of materials with high performance for practical applications [...

Atomic-Scale Understanding on the Tribological Behavior of Amorphous Carbon Films under Different Contact Pressures and Surface Textured Shapes.

The textured design of amorphous carbon (a-C) film can significantly improve the tribological performance and service life of moving mechanical components. However, its friction dependence on different texture shapes, especially under different load conditions, remains unclear. In particular, due to the lack of information regarding the friction interface, the underlying friction mechanism has still not been unveiled.

In Situ Formation of MoS on the Surface of CF to Improve the Tribological Properties of PUE.

The roller is an important part of the belt conveyor used in coal transportation. Due to the harsh environment of coal mines, the rollers are in a state of high load and high friction for a long time, which causes wear failure and has a serious impact on the reliability and safety of the equipment. In order to prepare roller material with excellent bearing performance and friction performance, CF/PUE composites were prepared by pouring method with polyurethane as the matrix and carbon fiber as reinforcement.

Electrospun fibrous membrane reinforced hydrogels with preferable mechanical and tribological performance as cartilage substitutes.

Hydrogels have attracted much attention as cartilage substitutes due to their human tissue-like characteristics. However, developing cartilage substitutes require the combination of high mechanical strength and low friction. Despite great success in tough hydrogels, this combination was hardly realized.

Bilayer Hydrogels with Low Friction and High Load-Bearing Capacity by Mimicking the Oriented Hierarchical Structure of Cartilage.

Natural articular cartilages exhibit extraordinary lubricating properties and excellent load-bearing capacity based on their penetrated surface lubricated biomacromolecules and gradient-oriented hierarchical structure. Hydrogels are considered as the most promising cartilage replacement materials due to their excellent flexibility, good biocompatibility, and low friction coefficient. However, the construction of high-strength, low-friction hydrogels to mimic cartilage is still a great challenge.

Fretting stimulation enhances bone growth at the interface between hydroxyapatite coating and bone.

Biologically fixed arthroplasty is limited in its development by the long postoperative recovery time and the low quality of solidity of the fixed interface in the short postoperative period. Therefore, fretting stimulation is used to accelerate the combination between bone tissue and the biological fixation interface of artificial joint prostheses. The effects of different compression loads and tangential micro-motion amplitude on the growth rate of bone tissue and the firm quality of fixation interface were studied by using two kinds of micro-motion stimuli: compression and tangential micro-motion.

Freestanding vascular scaffolds engineered by direct 3D printing with Gt-Alg-MMT bioinks.

There is an urgent need for vascular scaffolds as a treatment option for cardiovascular diseases in the clinic. Here, we developed a simple and effective method to fabricate vascular scaffolds by direct 3D printing in air with gelatine (Gt) - alginate (Alg) - montmorillonite (MMT) nanocomposite bioinks. This work includes the optimization of key 3D printing parameters and the characterization of microscopic morphology, physicochemical properties, mechanical properties and preliminary biological properties.

The antibacterial and wear-resistant nano-ZnO/PEEK composites were constructed by a simple two-step method.

Although the polyether ether ketone (PEEK) has excellent comprehensive properties, its non-antibacterial and low wear-resistant limit the wide application in the field of artificial joint materials. In this paper, Nano-ZnO was generated in situ on the surface of PEEK powder by one-step hydrothermal method, which improved the binding force of Nano-ZnO and PEEK matrix. Then the PEEK-based nanocomposites were prepared by melt blending with the synthesized Nano-ZnO-PEEK powders and PEEK powders.

3D printed chitosan-gelatine hydrogel coating on titanium alloy surface as biological fixation interface of artificial joint prosthesis.

To improve the fixation of the prosthesis-bone interface and to prevent postoperative infection, a novel antimicrobial hydrogel coating is designed as the biological fixation interface of the artificial joint prosthesis. Antimicrobial chitosan (CS) and gelatine (GT) were used as bioinks to print a CS-GT hydrogel coating with reticulated porous structure on the titanium alloy substrate by 3D printing technology. The experimental results show that the 7CS-10GT hydrogel coating has a macro-grid structure and honeycomb micro-network structure, excellent hydrophilicity (35.

Real-Time Dynamic Observation of Micro-Friction on the Contact Interface of Friction Lining.

This paper aims to investigate the microscopic friction mechanism based on in situ microscopic observation in order to record the deformation and contact situation of friction lining during the frictional process. The results show that friction coefficient increased with the shear deformation and energy loss of the surfacee, respectively. Furthermore, the friction mechanism mainly included adhesive friction in the high-pressure and high-speed conditions, whereas hysteresis friction was in the low-pressure and low-speed conditions.