Green Synthesis of Metal Oxides Semiconductors for Gas Sensing Applications.

During recent decades, metal oxide semiconductors (MOS) have sparked more attention in various applications and industries due to their excellent sensing characteristics, thermal stability, abundance, and ease of synthesis. They are reliable and accurate for measuring and monitoring environmentally important toxic gases, such as NO2, NO, N2O, H2S, CO, NH3, CH4, SO2, and CO2. Compared to other sensing technologies, MOS sensors are lightweight, relatively inexpensive, robust, and have high material sensitivity with fast response times. Green nanotechnology is a developing branch of nanotechnology and aims to decrease the negative effects of the production and application of nanomaterials. For this purpose, organic solvents and chemical reagents are not used to prepare metal nanoparticles. On the contrary, the synthesis of metal or metal oxide nanoparticles is done by microorganisms, either from plant extracts or fungi, yeast, algae, and bacteria. Thus, this review aims at illustrating the possible green synthesis of different metal oxides such as ZnO, TiO2, CeO2, SnO2, In2O3, CuO, NiO, WO3, and Fe3O4, as well as metallic nanoparticles doping.

An Overview of the Recent Developments in Metal Matrix Nanocomposites Reinforced by Graphene.

Two-dimensional graphene plateletes with unique mechanical, electrical and thermo-physical properties could attract more attention for their employed as reinforcements in the production of new metal matrix nanocomposites (MMNCs), due to superior characteristics, such as being lightweight, high strength and high performance. Over the last years, due to the rapid advances of nanotechnology, increasing demand for the development of advanced MMNCs for various applications, such as structural engineering and functional device applications, has been generated. The purpose of this work is to review recent research into the development in the powder-based production, property characterization and application of magnesium, aluminum, copper, nickel, titanium and iron matrix nanocomposites reinforced with graphene. These include a comparison between the properties of graphene and another well-known carbonaceous reinforcement (carbon nanotube), following by powder-based processing strategies of MMNCs above, their mechanical and tribological properties and their electrical and thermal conductivities. The effects of graphene distribution in the metal matrices and the types of interfacial bonding are also discussed. Fundamentals and the structure-property relationship of such novel nanocomposites have also been discussed and reported.

Preparation and characterisation of an innovative injectable calcium sulphate based bone cement for vertebroplasty application.

In this study, an innovative injectable and bioresorbable composite cement (Spine-Ghost) has been developed by combining a radiopaque glass-ceramic powder (SCNZgc) and spray-dried mesoporous bioactive particles (W-SC) into type III alpha calcium sulphate hemihydrate (α-CSH) (composition α-CSH/SCNZgc/W-SC, 70/20/10 wt%). The Spine-Ghost cement and pure α-CSH (as a reference) were characterised in terms of physical and mechanical properties and compared to a commercial reference (Cerament®- Bonesupport AB, Sweden). The Spine-Ghost cement had a setting time comparable with Cerament® showing a good injectability in the range of 8-20 minutes after the end of mixing. In addition, the Spine-Ghost cement showed a good radiopacity when compared with standard PMMA (BonOs Inject, aap Biomaterials GmbH Germany) and higher compressive strength when compared to healthy cancellous bone. The bioactivity of both Spine-Ghost and Cerament® was evaluated through in vitro soaking in simulated body fluid (SBF). Spine-Ghost samples were highly bioactive, inducing the precipitation of hydroxyapatite crystals in the first week of soaking in vitro. It was also found that the degradation kinetics of the Spine-Ghost cement were faster than those of pure α-CSH and comparable to those of Cerament® after approximately 1 month of soaking in SBF. Moreover, the Spine-Ghost cement was cytocompatible in indirect-contact culture in vitro. Overall results indicate that the Spine-Ghost cement might be a very good candidate for vertebroplasty application and could enhance new bone formation in vivo.