Effects of surface coating on reducing friction and wear of orthopaedic implants

Coatings such as diamond-like carbon (DLC) and titanium nitride (TiN) are employed in joint implants due to their excellent tribological properties. Recently, graphite-like carbon (GLC) and tantalum (Ta) have been proven to have good potential as coating as they possess mechanical properties similar to bones—high hardness and high flexibility. The purpose of this systematic literature review is to summarize the coating techniques of these four materials in order to compare their mechanical properties and tribological outcomes. Eighteen studies published between January 2000 and February 2013 have met the inclusion criteria for this review. Details of their fabrication parameters, material and mechanical properties along with the tribological outcomes, such as friction and wear rate, were identified and are presented in a systematic way. Although experiment conditions varied, we conclude that Ta has the lowest wear rate compared to DLC, GLC and TiN because it has a lower wear rate with high contact pressure as well as higher hardness to elasticity ratio. However, a further tribology test is needed in an environment which replicates artificial joints to confirm the acceptability of these findings

Unravelling the physics and mechanisms behind slips and falls on icy surfaces: a comprehensive review and nature-inspired solutions

Slip and Fall (SF) on slippery icy/snowy surfaces during winters is evident worldwide, especially in Nordic regions. Every year millions of people slip and fall due to ice accretion on the roads, streets, and pavements causing traumatic injuries, loss of limbs, and sometime loss of lives, costing billions in hospitals and recovery. An efficient anti-slipping winter shoe-sole could prevent these accidents and save lives. Footwear industries came up with solutions such like crampons, cleats, anti-skidding materials and tread pattern designs, but with limited success because of their ineffectiveness on wet ice, quick rate of wearing. The inspiration from nature like polar bear, seal, arctic fox, penguin, snake, octopus, frog, and gecko where this problem is elegantly solved through evolution process can address these limitations and design advanced anti-slippery surfaces. The review presents a comprehensive understanding of biological designs of the footpads (polar bear, penguin, arctic fox, frog, gecko) and skins (seal, snake, octopus’ suction cups) and recent progress on their translation for practical applications. The review emphasises on the mechanisms of icy slippery surfaces and the contact surfaces (shoe-sole and ice/snow) to mimic anti-slipping mechanism of animals and their movement on ice enabling to design the finest anti-slipping winter shoe-soles.This work is supported by the Foundation for Science and Technology (FCT) Portugal under the national support to R&D units’ grant through the reference project UIDB/04436/2020 and UIDP/04436/ 2020 and through the project “BioInSole-Multi-Functional Bioinspired Slip Resistant Shoe-Sole” with grant reference PTDC/EME-EME/7860/ 2020. VR acknowledges support from FCT for his individual PhD grant under the reference UI/BD/150939/2021. DL and MJN acknowledge support form Australian Research Council, ARC, (IH 150100003 and IH 120100025)

Natural high-porous diatomaceous-earth based self-floating aerogel for efficient solar steam power generation

The application of solar steam generation in seawater desalination is an effective way to solve the shortage of fresh water resources. At present, many kinds of photothermal conversion materials have been developed and used as evaporators in seawater desalination. However, some evaporators need additional thermal insulation or water supply devices to achieve efficient photothermal conversion. In addition, their complex, time consuming and no scalable preparation process, high cost of raw materials and poor salt resistance hinder the practical application of these evaporator. Owing to its distinctive nanoporous structure, diatomite as fossilized single-cells algae diatoms is a promising natural silica-based material for seawater desalination. They are taken from sea and that makes true sense to use them in the sea. Herein, we report the first example of synthesis robust three-dimensional (3D) natural-diatomite composite by assembling polyaniline nanoparticles covered diatomite into the polyvinyl alcohol pre-treated melamine foam frameworks and demonstrate its application as new evaporator for seawater desalination. The porous framework does not only improve the sunlight scattering efficiency, but also offer large network of channels for water transportation. The inherent mechanism behind salt desalination process involves the absorption of water molecules on the surface of the internal silica micro-nano pores, and evaporation under the heat induced by the polyaniline absorbed sunlight. Meanwhile, the metal ions are segregated by many available pores and channels to achieve the self-desalting effect. The developed evaporator possesses the superiority of multi-stage pore structure, strong hydrophilicity, low thermal conductivity, excellent light absorption, fast water transportation and salt-resistant crystallization as well as good durability. The evaporation rate without an additional device is found to be 1.689 kg m−2 h−1 under 1-Sun irradiation, and the energy conversion efficiency is as high as 95%. This work creates a platform and develops the prospect of employing green and sustainable natural-diatomite composite evaporator for practical applications of seawater desalination

Coupling graphene microribbons with carbon nanofibers : New carbon hybrids for high-performing lithium and potassium-ion batteries

Carbon‑carbon allotropic hybrids exhibit remarkable properties, including exceptional electrochemical charge storage capacities. A novel hybrid material composed of 1D carbon nanofibers (CNF) and 2D graphene micro-ribbons (GMR) was synthesized and incorporated as anodes in Li-ion batteries (LIB) and Potassium-ion batteries (KIB) for improved storage capacity. CNF-GMR material was hybridized simultaneously by one-step chemical vapour deposition (CVD) synthetic process, wherein the CNF were grown on the graphene surface using an iron oxide catalyst. Meanwhile, the GMRs were formed by the catalytic cutting of few-layer graphene. This unique carbon‑carbon allotropic hybrid exhibits excellent structural integrity, good electrical conductivity (718 S/m) and high specific surface area (305.6 g/m2). The as-prepared materials, when used as an anode in batteries, exhibited a highly reversible capacity (598 mAhg−1 and 410 mAhg−1 at 0.10 Ag−1 for LIB and KIB, respectively) with fast charging and discharging capability, and long-term cycling stability with 99% Coulombic efficiency over 1000 cycles.</p

Electrocatalytic activity of a 2D phosphorene-based heteroelectrocatalyst for photoelectrochemical cells

Research into efficient synthesis, fundamental properties, and potential applications of phosphorene is currently the subject of intense investigation. Herein, solution-processed phosphorene or few-layer black phosphorus (FL-BP) sheets are prepared using a microwave exfoliation method and used in photoelectrochemical cells. Based on experimental and theoretical (DFT) studies, the FL-BP sheets are found to act as catalytically active sites and show excellent electrocatalytic activity for triiodide reduction in dye-sensitized solar cells. Importantly, the device fabricated based on the newly designed cobalt sulfide (CoS ) decorated nitrogen and sulfur co-doped carbon nanotube heteroelectrocatalyst coated with FL-BP (FL-BP@N,S-doped CNTs-CoS ) displayed an impressive photovoltaic efficiency of 8.31 %, outperforming expensive platinum based cells. This work paves the way for using phosphorene-based electrocatalysts for next-generation energy-storage systems