The design of cheap and efficient oxygen reduction reaction (ORR) electrocatalysts is of a significant importance in sustainable and renewable energy technologies. Therefore, ORR catalysts with superb electrocatalytic activity and durability are becoming a necessity but still remain challenging. Herein, we report C/NiCo₂O₄ nanocomposite fibers fabricated by a straightforward electrospinning technique followed by a simple sintering process as a promising ORR electrocatalyst in alkaline condition. The mixed-valence oxide can offer numerous accessible active sites. In addition, the as-obtained C/NiCo₂O₄ hybrid reveals significantly remarkable electrocatalytic performance with a highly positive onset potential of 0.65 V, which is only 50 mV lower than that of commercially available Pt/C catalysts. The analyses indicate that C/NiCo₂O₄ catalyst can catalyze O₂-molecules via direct four electron pathway in a similar behavior as commercial Pt/C catalysts dose. Compared to single NiCo₂O₄ and carbon free NiCo₂O₄, the C/NiCo₂O₄ hybrid displays higher ORR current and more positive half-wave potential. The incorporated carbon matrices are beneficial for fast electron transfer and can significantly impose an outstanding contribution to the electrocatalytic activity. Results indicate that the synthetic strategy hold a potential as efficient route to fabricate highly active nanostructures for practical use in energy technologies.

Polymer matrix composites (PMC) have a competitive and dominant role in a lot of industries, like aerospace and automobiles. Short basalt fiber (SBF) is used to strengthen acrylonitrile–butadiene–styrene (ABS) polymers as a composite. The composite material is fabricated using injection molding with a new technique to obtain a uniform distribution for the ABS matrix at an elevated temperature range from 140 °C to 240 °C. Four types of specimen were produced according to the mechanically mixed amounts of SBF, which were (5, 10, 15, 20) wt %. The produced material was tested for tension, hardness and impact to measure the enhancement of the mechanical properties of the ABS only and the ABS reinforced by SBF composite. Wear tests were carried out using a pin on disc at a velocity of 57.5 m/s at three normal loads of 5, 10 and 15 kN. Tensile strength increased with up to 5 wt % of SBF, then decreased with an increasing amount of SBF reinforcement, while surface hardness increased with increasing SBF. The impact strength was found to degrade with the whole increment of SBF. Wear resistance increased with the increasing SBF reinforcement amount at all applied normal loads.

Hemp fibers are one of the strongest and stiffest available natural fibers and therefore have great potential for use in composite materials. This paper investigated the impact response of reinforcing PP by hemp fibers. Hemp fibers were added at (30%, 33%, 35%, 37%, and 40% wt). Influence of fiber's content on composite tensile strength and strain were revealed and the results show that at 33% wt the tensile strength of PP and hemp fiber composites was improved by 12.75%. At 33% wt, the fibers were longitudinally, at 45°, horizontally, and randomly oriented. The influence of fiber's orientation on both stress and strain of the composites was studied and the results showed that, when the fibers were longitudinally oriented, the tensile strength of the composites was higher than that of the other fiber's orientation. Also, the tensile strength of the composites at 33% wt was highly improved when the fibers were weaved and the tensile strength of the composite was improved by 25.98%. The effect of hemp fiber on the hardness of PP was deliberated where the hardness of the composite was increased by 5.77% better than that of pure PP.

Titanium and its alloys provide optimum metallurgical properties for implants. The formation of an oxide layer favours compatibility with the adjacent hard and soft tissues. This study is concerned with the improvement of hardness and wear resistance of Ti6Al-4V surface by thermal oxidation. In this study, comparative investigation of thermal oxidation treatment for Ti–6Al–4V was carried out to appropriate the oxidation conditions for further evaluation of wear performance. Hardness examination conducted under four different indentation loads of 200 gf to 1000 gf with a Vickers pyramid indenter revealed that surface hardness increased from 450 for untreated samples to 1300 Hv upon oxidation at 900oC for 45 h, which was accompanied by significant improvement in wear resistance. Characterization of modified surface layers was made by means of microscopic and X-ray diffraction analysis. This oxidation condition achieved 25 times higher wear resistance than the untreated alloy during reciprocating wear test conducted in a dry sliding.

Polyvinyl-chloride (PVC) is inexpensive, durable, and flexible thermoplastic material. PVC is one of the most versatile thermoplastics, and plays an important role in the plastic industry. This paper investigated the mechanical properties of reinforcing PVC by hemp fibers. Hemp fibers were added at different weight fractions (4.46%, 6.2%, 7.75%, 9%, and 11% wt). Influence of fiber's content on composite tensile strength and strain were revealed and the results showed that, at 6.2% wt the tensile strength of PVC 75, PVC 55 with hemp fiber composites was improved by 34.93% and 54.8% respectively. At 6.2% wt, the fibers were longitudinally, at 45°, horizontally, and randomly oriented. The influences of fiber's orientation on both stress and strain of the composites were studied and the results showed that, when the fibers were longitudinally oriented, the tensile strength of the composites was higher than that of the other fiber's orientation. Also, the tensile strength of the composites at 6.2% wt was highly improved, when the fibers were weaved. The effect of hemp fiber on the hardness of PVC was deliberated.

– Bone injuries and failures often require the inception of implant biomaterial. Recently, research in this area has received increasing attention. Particularly, porous metals are attractive due to its unique physical, mechanical, and new bone tissue ingrowth properties. In the present study, the production of highly porous Ti-6Al-4V parts by powder metallurgical technology is described. A space-holder method used carbamide with different particle size to produce parts with porosities between 35% to 70%. Spherical pores with size ranged from 560 µm to 1.0 mm were obtained depending on the size distribution of the space holder. The compressive strength and Young’s modulus of porous Ti-6Al-4V were determined. Results indicated that compressive strength and Young’s modulus decrease with increasing porosity and pore size. The porous parts are examined using scanning electron microscopy. The microstructure of porous materials is presented, aiming preferentially at biomedical applications. The results show that this process is promising to fabricate biomaterials for bone implants.