Sonocatalytic degradation of ciprofloxacin using synthesized TiO2 nanoparticles on montmorillonite

This article provides an overview of current research into the development, synthesis, photocatalytic bacterial activity, biocompatibility and cytotoxic properties of various visible-light active titanium dioxide (TiO2) nanoparticles (NPs) and their nanocomposites. To achieve antibacterial inactivation under visible light, TiO2 NPs are doped with metal and non-metal elements, modified with carbonaceous nanomaterials, and coupled with other metal oxide semiconductors. Transition metals introduce a localized d-electron state just below the conduction band of TiO2 NPs, thereby narrowing the bandgap and causing a red shift of the optical absorption edge into the visible region. Silver nanoparticles of doped TiO2 NPs experience surface plasmon resonance under visible light excitation, leading to the injection of hot electrons into the conduction band of TiO2 NPs to generate reactive oxygen species (ROS) for bacterial killing. The modification of TiO2 NPs with carbon nanotubes and graphene sheets also achieve the efficient creation of ROS under visible light irradiation. Furthermore, titanium-based alloy implants in orthopedics with enhanced antibacterial activity and biocompatibility can be achieved by forming a surface layer of Ag-doped titania nanotubes. By incorporating TiO2 NPs and Cu-doped TiO2 NPs into chitosan or the textile matrix, the resulting polymer nanocomposites exhibit excellent antimicrobial properties that can have applications as fruit/food wrapping films, self-cleaning fabrics, medical scaffolds and wound dressings. Considering the possible use of visible-light active TiO2 nanomaterials for various applications, their toxicity impact on the environment and public health is also addressed.

Visible-Light Active Titanium Dioxide Nanomaterials with Bactericidal Properties

Sonochemical assisted hydrothermal synthesis of pseudo-flower shaped Bismuth vanadate (BiVO4) and their solar-driven water splitting application.

Photocatalytic degradation of microcystin-LR by modified TiO2 photocatalysis: A review.

Photoelectrocatalytic degradation of oxalic acid using WO3 and stratified WO3/TiO2 photocatalysts under sunlight illumination

Fabrication of Fe-doped TiO2 nanoparticles and investigation of photocatalytic decolorization of reactive red 198 under visible light irradiation

The influence of soaking time in deep cryogenic treatment on the tensile and impact properties of low-alloy medium-carbon HY-TUF steel was investigated in this study. Microstructural studies based on phase distribution mapping by electron backscatter diffraction show that the deep cryogenic process causes a decrease in the content of retained austenite and an increase in the volume fraction of η-carbide with increasing soaking time up to 48 h. The decrease in the content of retained austenite from ~1.23vol% to 0.48vol% suggests an isothermal martensitic transformation at 77 K. The η-type precipitates formed in deep cryogenic-treated martensite over 48 h have the Hirotsu and Nagakura orientation relation with the martensitic matrix. Furthermore, a high coherency between η-carbide and the martensitic matrix is observed by high-resolution transmission electron microscopy. The variations in macrohardness, yield strength, ultimate tensile strength, and ductility with soaking time in the deep cryogenic process show a peak/plateau trend.

Influence of soaking time in deep cryogenic treatment on the microstructure and mechanical properties of low-alloy medium-carbon HY-TUF steel

This paper analyzes how a deep cryogenic process changes the microstructure and mechanical properties of a medium-carbon low-alloy steel. The light microscopy, microhardness testing, and transmission electron microscopy reveal that η-carbide and martensite are constituent phases of deep cryogenic treated (DCT) steel, while the microstructure of conventional heat-treated (CHT) steel consists of cementite, martensite, and retained austenite. Transmission electron microscopy also shows that the particles of η-carbide have the shape of ultra-fine globules in DCT martensite. The η-carbides grow in a Hirotsu and Nagakura orientation relationship to the martensitic matrix that enables highly coherent interphase boundaries. The results of the mechanical tests, including tensile and Charpy impact tests, show that the deep cryogenic process can improve toughness in terms of elongation (~12.81%), tensile fracture energy (~266 MPa), and the ductile–brittle transition temperature (~−17.2 °C). The results of fractography are also consistent with the improvement in toughness. It is also found that the strength and macrohardness values are increased. Unlike CHT steel, discontinuous yielding is observed in DCT steel. Moreover, there is no change in Young’s modulus due to the deep cryogenic treatment.

Effect of Deep Cryogenic Treatment on the Microstructure and Mechanical Properties of HY-TUF Steel

Effects of normalizing and annealing treatments on the microstructure of Ti-48Al-2Cr-2Nb (at.%) were investigated. Normalizing processes were done at 1385 ± 5 °C in α-phase domain with the heating rate of 10 °C/min, the average cooling rate of 30 °C/min, and the holding times of 5, 10, 15, 20, and 25 min. The annealing process was done at the same temperature and heating rate, the holding time of 15 min, and the average cooling rate of 2 °C/min. Microstructures, phases, and hardness levels were studied by optical and field emission electron microscopic observations, x-ray diffractometry (XRD), and microhardness testing, respectively. Also, crystallographic texture variations were analyzed by means of texture coefficient and XRD results. Experimental results showed a linear direct relationship between treatment time and grain size, up to 15 min. A linear reversed behavior was observed for longer times. The untreated alloy consisted of γ and α2 phases with a columnar morphology with the length of about 300 μm. A near-lamellar microstructure with equiaxed gamma grains, Widmansttaten, and laminar γ + α2 colonies was obtained by the normalizing process. The maximum reduction of the grain size was about 70%, as achieved by normalizing with the 15 min holding time. A texture-free microstructure was acquired by normalizing treatment in comparison with strong texture of the as-cast and annealed alloys.

Effects of Heat Treatment on Microstructural Modification of As-Cast Gamma-TiAl Alloy

The purpose of the present work was to investigate the effect of primary carbides and the δ-phase on the anisotropic ductile fracture of Inconel 718 in the forging process. Inconel 718 alloys were prepared by VIM + VAR processes with various carbon contents (0.009 and 0.027 wt.%). Then, the alloys were forged and annealed at temperatures of 980 and 1030 °C. The room temperature mechanical anisotropy of the alloys was evaluated at the longitudinal direction (LD) and transverse direction (TD). Tensile and impact tests were used to characterize the mechanical properties of the specimens. The microstructural characterization and the fractography of the alloys were carried out by FE-SEM. The obtained results showed that the fracture strain and the impact energy in the TD were 30-50% lower than the LD. The fracture was accelerated by the δ-phase, leading to the reduction of impact energy in the longitudinal and the lateral directions up to 50%. The low-carbon alloy indicated similar characteristics in both the LD and the TD. Aligned carbides changed the fracture path from a zigzag path in the LD to a fibrous path in the TD, while the δ-phase created a flat fracture path. The shear lip area ratio in the tensile fracture cross section was decreased by reducing ductility.

Seyed Rahman Hosseini

Papers

Fabrication of Fe-doped TiO2 nanoparticles and investigation of photocatalytic decolorization of reactive red 198 under visible light irradiation

Influence of soaking time in deep cryogenic treatment on the microstructure and mechanical properties of low-alloy medium-carbon HY-TUF steel

Effect of Deep Cryogenic Treatment on the Microstructure and Mechanical Properties of HY-TUF Steel

Effects of Heat Treatment on Microstructural Modification of As-Cast Gamma-TiAl Alloy

Effect of the As-Forged and Heat-Treated Microstructure on the Room Temperature Anisotropic Ductile Fracture of Inconel 718