Nanoparticles of Pt loaded on a vertically aligned TiO2 nanotube bed: synthesis and evaluation of electrocatalytic activity

Pt nano particle loaded TiO₂ nanotube (TiNT) electrode with excellent electrocatalytic activity was synthesized via seed mediated hydrothermal reduction method on self-aligned TiNT bed.

Studies to control biofilm formation by coupling ultrasonication of natural waters and anodization of titanium

The main objective of this study was to investigate the combined effect of ultrasonication of natural waters and anodization of titanium on microbial density and biofilm formation tendency on titanium surfaces. Application of 24 kHz, 400 W high power ultrasound through a 14 mm horn type SS (stainless steel) Sonicator with medium amplitude of 60% for 30 min brought about three order decrease in total bacterial density of laboratory tap water, cooling tower water and reservoir water and two order decrease in seawater. Studies on the effect of ultrasonication on dilute pure cultures of Gram-negative and Gram-positive bacteria showed five order and three order decrease for Pseudomonas sp. and Flavobacterium sp. respectively and two order and less than one order decrease for Bacillus sp. and Micrococcus sp. respectively. Ultrasonication increased lag phase and reduced logarithmic population increase and specific growth rate of Gram-negative bacteria whereas for Gram-positive bacteria specific growth rate increased. Studies on the biofilm formation tendency of these ultrasonicated mediums on titanium surface showed one order reduction under all conditions. Detailed biofilm imaging by advanced microscopic techniques like AFM, SEM and epifluorescence microscopy clearly visualized the lysed/damaged cells and membrane perforations due to ultrasonication. Combination of ultrasonication and anodization brought about maximum decrease in bacterial density and biofilm formation with greater than two order decrease in seawater, two order decrease in Bacillus sp. culture and more than four order decrease in Flavobacterium sp. culture establishing the synergistic effect of anodization and ultrasonication in this study.

In-vitro biocompatibility and corrosion resistance of strontium incorporated TiO2 nanotube arrays for orthopaedic applications

This article investigates the in-vitro biocompatibility and corrosion behaviour of strontium ion incorporated TiO2 nanotube arrays formed by anodization method for orthopaedic applications. The morphological studies were carried out using field emission scanning electron microscopy, atomic force microscopy, attenuated total reflectance fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and thin film X-ray diffraction techniques. The morphological investigation indicated that the length and the average diameter of nanotube were 2.1 ± 0.3 µm and 110 ± 4 nm, respectively. The wettability measurements showed that the TiO2 nanotube arrays have super wettability, as well as, strontium ion incorporated TiO2 nanotube arrays exhibited hydrophilic behaviour. Excellent in-vitro bioactivity was observed for TiO2 nanotube arrays with strontium ions. Electrochemical studies in Hank's solution showed that the TiO2 nanotube arrays with strontium ions have enhanced corrosion resistance.

Thermal Decomposition of Nitrated Tri-n-Butyl Phosphate in a Flow Reactor

Tri-n-butyl phosphate (TBP) is a universal nuclear extractant, commercially used in the PUREX process for the last 60 years. However, it is prone to nitration and thermal degradation, and as a consequence a red-oil event may be initiated under several operating conditions resulting in severe pressurization of vessel/cell if venting is inadequate. In this work, an attempt was made to understand the reaction pathway of thermal decomposition of nitrated TBP in a flow reactor at atmospheric pressure. Many reaction products were identified and quantified by instrumental methods like HPLC-RI and GC-TCD. The experimental data was analysed with a power law model and the apparent rate constants were estimated. The activation energy for thermal decomposition of nitrated TBP, assuming an Arrhenius type of temperature dependency, was estimated to be 47.39 ± 0.25 kJ·mol−1. The effect of both varying temperature and concentration of nitric acid on conversion of TBP into degradation products and products distribution was experimentally studied. Based on the experimental observations, a reaction mechanism framework for thermal decomposition of nitrated TBP is proposed.

New Data on Activity Coefficients of Potassium, Nitrate, and Chloride Ions in Aqueous Solutions of KNO3 and KCl by Ion Selective Electrodes

Ion selective electrodes (ISEs) are used to measure the single-ion activity coefficients in aqueous solutions of KNO3 and KCl at 298.15 K against a double-junction reference electrode. The EMF responses of ISEs up to 0.01 m are plotted to obtain the slope and intercept values. The obtained slopes and intercepts are used in Nernst equation for higher concentrated solutions for calculation of individual ion activity coefficient. The mean ionic activity coefficients are estimated from single ion activity coefficient, and the obtained results are compared with the literature values.

Synthesis of hydroxyapatite nanoparticles by a novel ultrasonic assisted with mixed hollow sphere template method

Hydroxyapatite (HAP) is the main inorganic component of bone material and is widely used in various biomedical applications due to its excellent bioactivity and biocompatibility. In this paper, we have reported the synthesis of hydroxyapatite nanoparticles by a novel ultrasonic assisted mixed template directed method. In this method glycine-acrylic acid (GLY-AA) hollow spheres were used as an organic template which could be prepared by mixing of glycine with acrylic acid. The as-synthesized HAP nanoparticles were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM) and tunnelling electron microscope (TEM) to investigate the nature of bonding, crystallinity, size and shape. The thermal stability of as-synthesized nanoparticles was also investigated by the thermo gravimetric analysis (TGA). The effect of ultrasonic irradiation time on the crystallinity and size of the HAP nanoparticles in presence of glycine-acrylic acid hollow spheres template were investigated. From the inspection of the above results it is confirmed that the crystallinity and size of the HAP nanoparticles decrease with increasing ultrasonic irradiation time. Hence the proposed synthesis strategy provides a facile pathway to obtain nano sized HAP with high quality, suitable size and morphology.