[Five million wear simulation and particle analysis of carbon-based nano-multilayer coatings titanium alloy femoral head]

Objective: To analyze the wear debris characteristics ofcarbon-based nano- multilayer coatings on Ti(6)Al(4)V alloys and compared with the cobalt chromium molybdenum alloy (CoCrMo) femoral head to evaluate the friction and wear performance of the new coated femoral head. Methods: Three groups were set up in the wear simulation experiment according to the type of femoral head. Group A: imported Cobalt-Chromium-Molybdenum alloy femoral head (CoCrMo); group B: Titanium alloy femoral head (Ti(6)Al(4)V) with carbon-based nano-multilayer coatings; group C: domestic Cobalt-Chromium-Molybdenum alloy femoral head (CoCrMo). All heads were jointed with an ultra-high molecular weight polyethylene (UHMWPE) acetabular cup. Serum samples were collected and stored in the hip joint simulator. After the sample has been digested and diluted, it was filtered through 5 μm, 1.2 μm and 0.4 μm filters, and the filter paper was collected for testing. Scanning electron microscope (SEM) was used to randomly select regions on the filter to obtain images of wear debris. Energy dispersive X-ray spectroscopy (EDS) was used to determine the elemental type of the particle and to eliminate possible contamination. The composition and structure of the abrasive chips were measured using Fourier transform infrared spectrometer (FTIR). The parameters related to the wear debris includingparticle size, shape, number and volume were calculated. The differences in correlation parameters between the groups were compared to evaluate the friction and wear properties of the new coated joints. Results: The main component of the wear debris produced was UHMWPE, and the particle size was mostly below 1 μm. The submicron particle ratio of group B was 49.4%, which was significantly lower than that of the group A and C (75% and 60%, respectively; χ(2)=66.032, 31.754, both P<0.017). The shape was mainly round, and there was no statistical difference between the groups (χ(2)=0.590, P=0.744). The number of particles in group B was significantly less than that of group C on all filters (t=9.960, 8.019, 5.790, all P<0.01), and less than group A on the 0.4 μm filter (t=7.810, P=0.000). Conclusion: The frictional wear performance of the new carbon-based nano-multilayer coatings femoral head is significantly better than that of the domestic femoral head, and even partially exceeds the imported femoral head level, which helps to reduce the production of particles and prevent osteolysis and aseptic loosening induced by UHMWPE particles.

Cobalt disulfide-modified cellular hierarchical porous carbon derived from bovine bone for application in high-performance lithium-sulfur batteries

Improving the insulating nature of sulfur and retaining the soluble polysulfides in sulfur cathodes are crucial for realizing the practical application of lithium-sulfur batteries (LSBs). Biomass-based carbon is becoming increasingly popular for fabricating economical and efficient cathodes for LSBs owing to its unique structure. Herein, we report a facile strategy to transform bovine bone with an organic-inorganic structure into cellular hierarchical porous carbon via carbonization and KOH activation, followed by CoS₂ modification through hydrothermal treatment. The synthesized composite can load abundant sulfur and produce a dual effect of "physical confinement and chemical entrapment" on polysulfides. The conductive carbon frame with the developed porous structure provides adequate space to accommodate sulfur and physically suppress the shuttle effect of polysulfides. The embedded half-metallic CoS₂ sites can chemically anchor the polysulfides and enhance the electrochemical reaction activity as well. Owing to the multifunctional structure and dual restraint effect, the designed electrode exhibits enhanced electrochemical properties including high initial capacity (1230.9 mAh g^-1 at 0.2 C), improved cycling stability and enhanced rate capability.

Niobium doped tungsten oxide mesoporous film with enhanced electrochromic and electrochemical energy storage properties

Exploring high performance cathode materials is of great means for the development of bi-functional electrochromic energy storage devices. Herein, Nb-doped WO₃ mesoporous films as integrated high-quality cathode are successfully constructed via a facile sol-gel method. Chemical state and crystallinity of the WO₃ based films are significantly influenced by doping concentration. Compared with the pure WO₃, the optimal Nb-doped film shows improved optical-electrochemical properties with high specific capacity (74.4 mAh g^-1 at 2 A g^-1), excellent high-rate capability, large optical contrast (61.7% at 633 nm), and ultra-fast switching speed (3.6 s and 2.1 s for coloring and bleaching process, respectively). These positive features suggest the potential application of Nb-doped WO₃ mesoporous cathode. Our research paves the way for the development of multifunctional photoelectrochemical energy devices.

Super Antiwetting Surfaces for Mitigating Drag-Out of Deep Eutectic Solvents

Deep eutectic solvents (DESs) are, at room temperature, about dozens to hundreds of times more viscous than water, which brings pretty thick residues on solid surfaces, for example, causing drag-out and weight loss in the transfer process. Unfortunately, until now little work had been done for solving this knotty problem. In this study, the super antiwetting surface, i.e., super-DES-phobic surface (defined as DES contact angle > 150°) is proposed and fabricated successfully by a facile coating technique. Hierarchical silver dendrites on copper foam substrate provide effective dual-roughness surfaces showing stable superDESphobicity. The superDESphobic surface can repel the DESs and their derived solutions even under elevated temperature of about 120 °C and the impact attack of drops. It is also found that the superDESphobic surface can significantly delay the DESs freezing and reduce the adhesion strength of the frozen DESs. Interestingly, the superDESphobic surface can be applied as an effective tool for gauging the density of DES using an ∼2 μL droplet in virtue of its super antiwetting property. The super antiwetting surfaces show promise for potential applications in DES self-cleaning and antifreezing.

Mechanical tests, wear simulation and wear particle analysis of carbon-based nanomultilayer coatings on Ti6Al4V alloys as hip prostheses

Carbon-based nanomultilayer coatings were deposited on medical-grade Ti₆Al₄V alloy using a magnetron sputtering technique under a graded bias voltage.

Investigation of silicon carbon nitride nanocomposite films as a wear resistant layer in vitro and in vivo for joint replacement applications

Silicon-contained CN_x nanocomposite films were prepared using the ion beam assisted magnetron sputtering under different nitrogen gas pressure. With increase of the nitrogen pressure, silicon and nitrogen content of the CN_x films drastically increase, and is saturated as the P_N2 reach about 40%. Surface roughness and the contact angle are increase, while the friction coefficient decreased. The CN_x film with 5.7at.% Si content possess the lowest friction coefficient of only 0.07, and exhibited the best tribological properties. The impact of CN_x films with different silicon content on the growth and the activation of osteoblasts were compared to that of Ti6Al4V. The incorporation of silicon in the CN_x film also showed an increase cell adhesion. Bonding structure and surface energy were determined to be the factors contributing to the improved biocompatibility. Macrophages attached to 5.7at.% Si contained CN_x films down regulated their production of cytokines and chemokines. Moreover, employed with Si contained CN_x coated joint replacements, which were implanted subcutaneously into Sprague-Dawley mice for up to 36days, the tissue reaction and capsule formation was significantly decreased compared to that of Ti6Al4V. A mouse implantation study demonstrated the excellent in vivo biocompatibility and functional reliability of wear resist layer for joint replacements with a Si doped a-CN_x coating for 36days.

Superior ethanol-sensing behavior based on SnO2 mesocrystals incorporating orthorhombic and tetragonal phases

Nanoporous SnO₂ mesocrystal with mixed tetragonal and orthorhombic phases and superior ethanol-sensing performance is synthesized via a facile annealing topotactic transformation from the ionothermal synthesized SnO precursor under ambient-pressure.

Anomalous self-reduction of layered double hydroxide (LDH): from α-Ni(OH)2 to hexagonal close packing (HCP) Ni/NiO by annealing without a reductant

An anomalous self-reduction phenomenon can occur for Ni LDH synthesized from an ionic liquid system.

A highly porous NiO/polyaniline composite film prepared by combining chemical bath deposition and electro-polymerization and its electrochromic performance

A highly porous NiO/polyaniline (PANI) composite film was prepared on ITO glass by combining the chemical bath deposition and electro-polymerization methods, successively. The porous NiO film acts as a template for the preferential growth of PANI along NiO flakes, and the NiO/PANI composite film has an intercrossing net-like morphology. The electrochromic performance of the NiO/PANI composite film was investigated in 1 M LiClO(4)+1 mM HClO(4)/propylene carbonate (PC) by means of transmittance, cyclic voltammetry (CV) and chronoamperometry (CA) measurements. The NiO/PANI thin film exhibits a noticeable electrochromism with reversible color changes from transparent yellow to purple and presents quite good transmittance modulation with a variation of transmittance up to 56% at 550 nm. The porous NiO/polyaniline (PANI) composite film also shows good reaction kinetics with fast switching speed, and the response time for oxidation and reduction is 90 and 110 ms, respectively.

Photoassisted Charge Behavior of Hydrogen Storage Alloy-TiO2/Pt Electrodes

The photoassisted charge behavior of hydrogen storage alloy modified with TiO2/Pt nanocomposites (HSA-TiO2/Pt electrode) was investigated. The HSA-TiO2/Pt electrode can be photocharged under current. The mechanism of photoassisted behavior of the HSA-TiO2/Pt electrode was explained through the results of cyclic voltammogram and impedance measurements of the HSA-TiO2/Pt electrode. Upon illumination, the photogenerated electrons can charge the electrode, but the photogenerated holes may oxidize the hydrogen storage alloy to form a layer of metal oxide. Because the current could keep the electrode active, the H atoms produced by photogenerated electrons diffused to the hydrogen storage alloy and a metal hydride formed. The electrode delivered a higher discharge capacity due to the assistance of photocharge.