M. Z. H. Khan

Graphene Oxide Modified Electrodes for Dopamine Sensing

Dopamine (DA) is one of the most important catecholamine neurotransmitters that plays an important role in the central nervous, renal, hormonal, and cardiovascular systems. Since its discovery, tremendous effort has been made and various techniques have been developed for the DA detection. Recently, graphene-based materials have attracted a tremendous amount of attention due to their high sensitivity and rapid response towards effective detection of DA. This review focuses on current advances of graphene-based materials for DA detection based on recent articles published in the last five years.

Effect of ITO surface properties on SAM modification: A review toward biosensor application

Abstract The aim of this review is to discuss the effect of physical and chemical properties of Indium tin oxide (ITO) thin film on its self-assembled monolayer (SAM) modification, as well as device performance toward biosensor applications. The emphasis is on surface morphology studies of the thin films in order to provide connecting points between surface properties with the broader field of material science of ITO. The morphology of SAM film deposited on it directly affects by the properties of these prepared ITO film. Thus, it is a topic of interest to study the influence of physiochemical properties of this film on device fabrication and applications as biosensor platform.

Nanoparticles Modified ITO Based Biosensor

Incorporation of nanomaterials with controlled molecular architecture shows great promise in improving electronic communication between biomolecules and the electrode substrate. In electrochemical applications metal nanoparticles (NPs) modified electrodes have been widely used and are emerging as candidates to develop highly sensitive electrochemical sensors. There has been a growing technological interest in modified indium tin oxide (ITO) electrodes due to their prominent optoelectronic properties and their wide use as a transducing platform. The introduction of NPs into the transducing platform is commonly achieved by their adsorption onto conventional electrode surfaces in various forms, including that of a composite. The aim of this review is to discuss the role of metallic NPs for surface fabrication of ITO thin films leading to detection of specific biomolecules and applications as a biosensor platform.

Deposition of an Ultraflat Graphene Oxide Nanosheet on Atomically Flat Substrates

In this study, graphene oxide (GO) sheets produced in the form of stable aqueous dispersions were deposited on Au (111), freshly cleaved mica, and highly oriented pyrolytic graphite (HOPG) substrates. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) were used to study the presence and distinct contact of GO sheets on the substrates. It was revealed from the topography images that high-quality ultraflat GO monolayer sheets formed on the substrates without distinct cracking/wrinkling or folding. GO sheets with apparent height variation observed by microscopy also indicate ultraflat deposition with clear underlying steps. It was observed that ultrasonication and centrifuge steps prior to deposition were very effective for getting oxidation debris (OD)-free ultraflat single monolayer GO nanosheets onto substrates and that the process depends on the concentration of supplied GO solutions.

Pyrolytic Waste Plastic Oil and Its Diesel Blend: Fuel Characterization.

The authors introduced waste plastic pyrolysis oil (WPPO) as an alternative fuel characterized in detail and compared with conventional diesel. High density polyethylene, HDPE, was pyrolyzed in a self-designed stainless steel laboratory reactor to produce useful fuel products. HDPE waste was completely pyrolyzed at 330–490°C for 2-3 hours to obtain solid residue, liquid fuel oil, and flammable gaseous hydrocarbon products. Comparison of the fuel properties to the petrodiesel fuel standards ASTM D 975 and EN 590 revealed that the synthetic product was within all specifications. Notably, the fuel properties included a kinematic viscosity (40°C) of 1.98 cSt, density of 0.75 gm/cc, sulphur content of 0.25 (wt%), and carbon residue of 0.5 (wt%), and high calorific value represented significant enhancements over those of conventional petroleum diesel fuel.

Paper Making from Banana Pseudo-Stem: Characterization and Comparison

This study deals with the determination of paper-making potentialities of banana pseudo-stems growing in Thailand. Chlorine dioxide (Do and D1) and extraction (Ep) treatments were all performed in sealed plastic bags in a thermostatically controlled water bath. Unbleached banana kraft pulp in the kappa number range of 23–28 was not easy to bleach with three-stage sequence of D0-EP-D1. The determination of mechanical properties of standard paper after mild beating in the laboratory is discussed as is the interpretation of the results. As an indication of potential paper-making properties, they are important for the pulp producer in the control of fiber characteristics. The brightness was achieved at 45% ISO, with a viscosity level at 585 mL/g. Drainage of pulp was extremely slow and paper-making properties were characterized by low strength, low bulk, rough surface, and extremely poor optical properties.

Formation and Characterization of Copper Nanocube-Decorated Reduced Graphene Oxide Film

In this study, we present a new approach for the formation and deposition of Cu nanocube-decorated reduced graphene oxide (rGO-CuNCs) nanosheet on indium tin oxide (ITO) electrode using very simple method. Cubic Cu nanocrystals have been successfully fabricated on rGO by a chemical reduction method at low temperature. The morphologies of the synthesized materials were characterized by ultraviolet-visible (UV-vis) spectroscopy, scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and atomic force microscopy (AFM). The as-formed CuNCs were found to be homogeneously and uniformly decorated on rGO nanosheets. We demonstrated that the individual rGO sheets can be readily reduced and decorated with CuNCs under a mild condition using L-ascorbic acid (L-AA). Such novel ITO/rGO-CuNCs represent promising platform for future device fabrication and electrocatalytic applications.

The role of drug as corrosion inhibitor for mild steel surface characterization by SEM, AFM, and FTIR

Purpose The purpose of this study is to understand the inhibitor behavior of specific drug against mild steel corrosion and their adsorption mechanism on the surface. Design/methodology/approach Corrosion rates are influenced by the formation of inhibitor aggregates at the mild steel surface. Detail surface characterizations of mild steel have been studied before and after adsorption of drugs in 1N HCl solution. Scanning electron microscopy, atomic force microscopy and Fourier transform infrared spectroscopy were used to examine the effect of drug adsorption on steel surface. Findings Scanning electron microscopy analysis suggested that the metal had been protected from aggressive corrosion because of the addition of the inhibitors. Atomic force microscopy visualization confirmed the formation of protective layer on steel surface, resulting in the decrease in surface roughness with corrosion rates. The nature of metal surface has been analyzed by Fourier transform infrared spectroscopy. Originality/value The findings of this study will help us to understand the interaction of specific drugs with mild steel surface and their potential inhibition mechanism.

Rapid Biological Synthesis of Silver Nanoparticles from Ocimum sanctum and Their Characterization

With development of nanotechnology, the biological synthesis process deals with the synthesis, characterization, and manipulation of materials and further development at nanoscale which is the most cost-effective and eco-friendly and rapid synthesis process as compared to physical and chemical process. In this research silver nanoparticles (AgNPs) were synthesized from silver nitrate (AgNO3) aqueous solution through eco-friendly plant leaf broth of Ocimum sanctum as reactant as well as capping agent and stabilizer. The formation of AgNPs was monitored by ultraviolet-visible spectrometer (UV-vis) and Fourier transform infrared (FTIR) spectroscopy. X-ray diffraction (XRD) and scanning electronic microscopy (SEM) have been used to characterize the morphology of prepared AgNPs. The peaks in XRD pattern are in good agreement with that of face-centered-cubic (FCC) form of metallic silver. Thermal gravimetric analysis/differential thermal analysis (TGA/DTA) results confirmed the weight loss and the exothermic reaction due to desorption of chemisorbed water. The average grain size of silver nanoparticles is found to be 29 nm. The FTIR results indicated that the leaf broths containing the carboxyl, hydroxyl, and amine groups are mainly involved in fabrication of silver AgNPs and proteins, which have amine groups responsible for stabilizing AgNPs in the solution.

Co recovery from spent Li-ion battery by acid leaching - a comparative study

We investigated and compared leaching processes with different acids for the recovery of cobalt from the cathode active materials of spent lithium-ion batteries. The active substances separated from the cathode of spent lithium-ion batteries were dissolved in each acid solutions, and precipitated as CoC2O4•2H2O. The structural morphology of the cathode materials before and after leaching were characterised by X-ray diffraction (XRD). The amount of Co present in the leachate was determined by atomic absorption spectrophotometry (AAS). The experimental study shows that 93% of Co (mass fraction) can be dissolved in the solution of 1.5 M HCl, 2.0% H2O2 (volume fraction), and S:L of 20 g/L−1 results the highest efficient recovery within 60 min at 90°C comparing other acids in this study.