Modifying the photocatalytic property of ZnO-based photoelectrodes by introducing MgFe2O4 nanoparticles

Journal of Materials Science: Materials in Electronics - Limited light absorption and acute charge recombination on the surface of ZnO nanostructure-based photoelectrodes are the basic challenges...     

Bioceramic composites for orthopaedic applications: A comprehensive review of mechanical,biological, and microstructural properties

Bioceramics have been widely utilized for orthopaedic applications in which the biocompatibility and mechanical properties of the materials are vital characteristics to be considered for their clinical use. Till date, extensive studies have been devoted to developing a range of scientific ways for tailoring the microstructure of bioceramics in order to attain the trade-off of mechanical properties and biocompatibility of the final product. Owing to low reactivity, earlier stabilization and longer functional life of bioceramic, the developed implants are capable of replicating the mechanical behaviour of original bone. As the safety of the patient and its ultimate functionality are the ultimate goal of the selected implant material hence, the present literature survey investigates and brings forth the important aspects associated to the mechanical, biological and microstructural characteristics of bioceramics employed in orthopaedic applications. The review paper majorly focuses on effective utilization of various materials as an additive in bioceramics and processing techniques used for enhancement of properties, enabling the use of material in orthopaedic applications. The influence of various additives on the microstructure, mechanical properties and biological performance of developed bioceramics orthopaedic implants has been elaborately discussed. Furthermore, future prospects are proposed to promote further innovations in bioceramics research.     

Ionic liquid-based deep eutectic solvents as novel solvent-cum-catalyst media for thermal dehydrogenation of chemical hydrides

The current work explores the usage of novel synthesized Deep Eutectic Solvent (DES) as a catalyst cum solvent media for the thermal dehydrogenation of chemical hydrides, namely Ammonia Borane (AB) and Ethylene diamine bisborane (EDAB). In the first instance, the quantum chemistry based COSMO-SAC (COnductor like Screening MOdel Segment Activity Coefficient) model was used for the selection of the pertinent solvent. 1-Butyl-3-methylimidazolium methanesulfonate: Imidazole ([BMIM][MeSO₃]:[Im]) turned out to be an ideal eutectic mixture with the highest predicted solubility with amine boranes. The DES was synthesized by combining the Hydrogen Bond Acceptor (HBA), namely 1-Butyl-3-methylimidazolium methanesulfonate and Imidazole as Hydrogen Bond Donor (HBD) at a molar ratio of 1:2 and T = 70 °C. The formation of DES was confirmed by recording the NMR spectra. Further, the thermal dehydrogenation study was performed at a vacuum of 4 × 10^?2 mbar (gauge pressure) of AB/DES and EDAB/DES systems at 105 °C, where a hydrogen equivalent of 1.40 and 2.55 was produced, respectively. The residual samples were further analyzed through ¹H NMR analysis for the reaction mechanism and to confirm the role of Ionic Liquid-based DES as catalyst cum solvent media.     

Alginate–chitosan composite hydrogel film with macrovoids in the inner layer for biomedical applications

Making of a layered composite using two biopolymer gels with regularly aligned voids in the inner layer is described in this article. Calcium alginate constituted the inner layer, within which voids of 500 μm diameter were embedded in monolayer or in multiple layers using a fluidic device for bubbling. The chitosan without any additional crosslinker was used to form the outer layer. The layered structure enabled compartmentalization of drug hold-up, and differential release rates. These aspects were reviewed using bovine serum albumin and vitamin B₁₂ as model solutes. The presence of voids at the inner layer of alginate increased the uptake, raising the level of absorptivity to more than 4000%. The composite film could hold two solutes at a time. The one, held inside the alginate layer started releasing only after 1 h of dipping in the release media. The adhesive strength between layers and the response of the composite film to compressive deformation are studied here. The effect of single or multiple layers of voids in the inner layer is reviewed. The slowing of degradation rate due to chitosan-encapsulation is experimentally determined. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47599.     

Lab scale optimization of various factors for photocatalytic hydrogen generation over low cost Cu0.02Ti0.98O2-δ photocatalyst under UV/Visible irradiation and sunlight

We have demonstrated earlier that maximum H₂ generated @ 1.167 l/h/m² over Cu_0.02Ti_0.98O_2-δ photocatalyst with apparent quantum efficiency, AQE of 7.5% and solar fuel efficiency, SFE of 3.9% under sunlight. With an aim to scale-up the solar photocatalytic hydrogen process to pilot plant, optimization studies at lab scale as well as in upscaled photoreactors were performed over Cu_0.02Ti_0.98O_2-δ, photocatalyst under UV/visible and sunlight. Cu_0.02Ti_0.98O_2-δ was synthesized by facile sol-gel route and characterized by relevant techniques. Several operational parameters were investigated in order to finalize the conditions which are most favourable for photocatalytic hydrogen yield. Factors such as photocatalyst loadings, v/v concentration of sacrificial reagent, replacement of methanol by industrial waste glycerol, role of different configuration of light source with reactor, effect of stirring during the photocatalytic reaction, effect of fluctuations of solar flux at hourly basis, illumination area on hydrogen yield were studied. Contribution of each factor in determining the hydrogen yield was quantified. Relative standard deviation in hydrogen yield as a function of each factor was estimated. Our findings suggest that in addition to catalyst loadings and sacrificial reagent, improved dispersion of photocatalyst obtained by stirring the reaction mixture in horizontal geometry resulted in enhanced H₂ yield. Hydrogen yield obtained at lab scale can be appropriately extrapolated with respect to illumination area instead of weight of photocatalyst. A relative standard deviation (RSD) of ± 3.82% and ± 4.53% in H₂ yield was calculated for sunny and cloudy days in time zone of 10.30–16.30 h IST. Deviation of H₂ yield was more on cloudy days and beyond 16:30 h. These studies have provided a daily window of 11:00–15:00 h to be utilized throughout the year for a commercial scaled up process, prohibiting the illumination during less productive hours of the day for shaping the improved economics of solar hydrogen generation. Our results obtained at lab scale would be useful to perform sunlight driven scaled –up photocatalytic process using low cost visible light efficient photocatalyst, Cu_0.02Ti_0.98O_2-δ.     

Impact of adhesive ingredients on adhesion between rubber and brass-plated steel wire in tire

Proficiency on underlying mechanism of rubber-metal adhesion has been increased significantly in the last few decades. Researchers have investigated the effect of various ingredients, such as hexamethoxymethyl melamine, resorcinol, cobalt stearate, and silica, on rubber-metal interface. The role of each ingredient on rubber-metal interfacial adhesion is still a subject of scrutiny. In this article, a typical belt skim compound of truck radial tire is selected and the effect of each adhesive ingredient on adhesion strength is explored. Out of these ingredients, the effect of cobalt stearate is found noteworthy. It has improved adhesion strength by 12% (without aging) and by 11% (humid-aged), respectively, over control compound. For detailed understanding of the effect of cobalt stearate on adhesion, scanning electron microscopy and energy dispersive spectroscopy are utilized to ascertain the rubber coverage and distribution of elements. X-ray photoelectron spectroscopy results helped us to understand the impact of Cu_XS layer depth on rubber-metal adhesion. The depth profile of the Cu_XS layer was found to be one of the dominant factors of rubber-metal adhesion retention. Thus, this study has made an attempt to find the impact of different adhesive ingredients on the formation of Cu_XS layer depth at rubber-metal interface and establish a correlation with adhesion strength simultaneously.     

Extrusion of highly filled flexible polymer sheet

Highly-filled polymer systems include color masterbatches, feedstocks for powder injection molding, and rigid sheets with high levels of flame retardants, but they have not been explored for flexible sheet. This work investigated the (a) selecting a polymer matrix with enough melt strength and flexibility to form a stable sheet with high filler loading, (b) the maximum achievable filler loading for the sheet, and (c) optimizing the process of extruding a highly-filled flexible polymer system. Extrusion grade low-density polyethylene (LDPE) provided sufficient flexibility and permitted a maximum filler loading of 36 vol% (~78 wt%). Good dispersion of the nanoparticle filler, however, required two passes through multiple screw extruders and a small reduction in the viscosity of the LDPE. Sheet with thickness of 415 μm, surface roughness of <1 μm, and sufficient flexibility was extruded continuously at a rate of 10 m/min., but it required a more traditional coat hanger manifold to prevent filler hang up in the sheet die. The filler particles were distributed uniformly through the core and skin of the sheet, giving the sheet good mechanical properties.