IR@CMERI - The Central Mechanical Engineering Research Institute (CSIR)
IR@CMERI - The Central Mechanical Engineering Research Institute (CSIR)Not a member yet
731 research outputs found
Sort by
Ammonia-Assisted Growth of CoSn(OH)6 Nanostructures and Their Electrochemical Performances for Supercapacitor
No full textIn this work, ammonia-assisted one step growth of SnO₂ and mixed metal hydroxide CoSn(OH)6 on Ni foam is illustrated. The nanostructured films grown on Ni foam are highly porous in nature. The CoSn(OH)6 nanostructures were deposited using three different molar ratios of Sn/Co precursors i.e., 1:1, 1:2 and 2:1 and their performances as supercapacitor have been investigated and compared with pristine SnO₂. Interestingly, the CoSn(OH)6 thin films prepared with 1:2 molar ratio of Sn/Co showed remarkably high areal capacitance and good cyclic stability. It is believed that the presence of different metal cations and their valence states along with the porous nanostructure makes the material outstanding as supercapacitor. The highest areal capacitance of 4189 mF cm-2 was obtained at a current density of 2 mA cm-2 for CoSn(OH)6 thin films offering an excellent cyclic stability with a capacity retention of 90.3% after 2000 cycles
Borane phosphonate DNA: a versatile unnatural internucleotide linkage
No full textBorane phosphonate (bp) is a new class of unnatural internucleotide linkages where one of the oxygens in the phosphodiester linkage is replaced by an electron deficient borane (BH3) group. These unnatural internucleotide linkages are resistant to nuclease, RNase H active and hydrophobic, which significantly enhance the cellular uptake. The bp-linked oligo can be synthesized both enzymatically and chemically. Like borane (BH3) and diborane (B2H6) reagents, the borane group (BH3) in borane phosphonate oligo retains its reactivity towards a specific substrate. BpDNA reduces metal ions, such as Au(III), Ag(I), and Pt(II), and produces the corresponding metal nanoparticles; this enables the DNA-mediated morphology control and spatial positioning of nanoparticles and DNA nanostructures. Moreover, the bp-diesters undergo oxidative substitution with various nucleophiles, such as amines, alcohols, thiols, etc., upon activation by iodine; this leads to a route for post-synthetic modification of DNA including DNA functionalization. This article discusses some of the recent studies reported on bp-oligo synthesis and its applications
Effect of Ion Diffusion in Cobalt Molybdenum Bimetallic Sulfide toward Electrocatalytic Water Splitting
No full textThe electrocatalyst comprising two different metal atoms is found suitable for overall water splitting in alkaline medium. Hydrothermal synthesis is an extensively used technique for the synthesis of various metal sulfides. Time-dependent diffusion of the constituting ions during hydrothermal synthesis can affect the crystal and electronic structure of the product, which in turn would modulate its electrocatalytic activity. Herein, cobalt molybdenum bimetallic sulfide was prepared via hydrothermal method after varying the duration of reaction. The change in crystal structure, amount of Co–S–Mo moiety, and electronic structure of the synthesized materials were thoroughly investigated using different analytical techniques. These changes modulated the charge transfer at the electrode–electrolyte interface, as evidenced by electrochemical impedance spectroscopy. The Tafel plots for the prepared materials were investigated considering a less explored approach and it was found that different materials facilitated different electrocatalytic pathways. The product obtained after 12 h reaction showed superior catalytic activity in comparison to the products obtained from 4, 8, and 16 h reaction, and it surpassed the overall water splitting activity of the RuO2–Pt/C couple. This study demonstrated the ion diffusion within the bimetallic sulfide during hydrothermal synthesis and change in its electrocatalytic activity due to ion diffusion
Effect of stereochemical conformation into the corrosion inhibitive behaviour of double azomethine based Schiff bases on mild steel surface in 1 mol L−1 HCl medium: An experimental, density functional theory and molecular dynamics simulation study
No full textTwo hitherto unexplored double condensed Schiff bases, namely, 4-(4-((Pyridin-2-yl)methyleneamino)phenoxy)-N-((pyridin-2-yl)methylene)benzenamine (PMB) and 4-(4-(4-((Pyridin-2-yl)methyleneamino)phenoxy)phenoxy)-N-((pyridin-2-yl)methylene)benzenamine (PPMB) were synthesized and their corrosion inhibitive performances on mild steel have been investigated in 1 mol L−1 HCl medium by gravimetric and electrochemical measurements. Field emission scanning electron microscopy, energy dispersive X-ray spectroscopy and atomic force microscopy affirmed the formation of protective films on mild steel surfaces. Contact angle measurement revealed the hydrophobic nature of surface modified by the inhibitor molecules applied in the corrosive solution. The influence of molecular configuration in corrosion inhibition behaviour of inhibitors has been explored by DFT, DFTB calculation and MD simulation
Gold nanoparticle-assisted enhancement in the anti-cancer properties of theaflavin against human ovarian cancer cells
No full textRedox-active quinones have been reported to show good potential for biological activities, while efforts are directed to explore the usefulness of these materials further in cancer management. Our previous study demonstrated that theaflavin and theaflavin-gallates (tea-extracted polyphenols) selectively induce apoptosis of tumour cells in vitro, but its concentration for showing half-maximal therapeutic response remains a matter of concern. In this report, we demonstrated that if theaflavin is conjugated with gold nanoparticles (AuNPs) to form a nanoconjugate AuNP@TfQ, its apoptotic ability increases significantly in comparison to the bare theaflavin (Tf). The nanoconjugate is prepared by following a one-step green synthesis ̶ a reaction between HAuCl4 and the aflavin at room temperature. AuNP@TfQ is characterized using particle size analysis, FESEM, UV–vis, FTIR, fluorescence, and X-ray photoelectron spectroscopytechniques. We assume that the enhanced anti-cancer effect of AuNP@TfQ appears due to the facile oxidation of the pristine theaflavin to its quinone derivative on the surface of AuNPs. The presence of quinone motif in AuNP@TfQ induces an increased level of ROS generation probably through the depolarization of mitochondria and resulted in the caspase-mediated apoptotic cell death which may hold the potential for a “magic bullet”-mediated ovarian cancer treatment
Biodiesel production from waste cooking oil using heterogeneous catalysts and its operational characteristics on variable compression ratio CI engine
No full textIn the present work, the optimum biodiesel conversion from waste cooking oil to biodiesel through transesterification method was investigated. The base catalyzed transesterification under different reactant proportions such as the molar ratio of alcohol to oil and mass ratio of catalyst to oil was studied for optimum production of biodiesel. The optimum condition for base catalyzed transesterification of waste cooking oil was determined to be 12:1 and 5 wt% of zinc doped calcium oxide. The fuel properties of the produced biodiesel such as the calorific value, flash point and density were examined and compared to conventional diesel. The properties of produced biodiesel and their blend for different ratios (B20, B40, B60, B80 and B100) were comparable with properties of diesel oil and ASTM biodiesel standards. Tests have been conducted on CI engine which runs at a constant speed of 1500 rpm, injection pressure of 200 bar, compression ratio 15:1 and 17.5, and varying engine load. The performance parameters include brake thermal efficiency, brake specific energy consumption and emissions parameters such as Carbon monoxide (CO), Hydrocarbon (HC), Oxides of Nitrogen (NOx) and smoke opacity varying with engine load (BP). Diesel engine's thermal performance and emission parameters such as CO, HC, and NOx on different biodiesel blends demonstrate that biodiesel produced from waste cooking oil using heterogeneous catalyst was suitable to be used as diesel oil blends and had lesser emissions as compared to conventional diesel
Discrimination of 1‐ and 2‐Propanol by Using the Transient Current Change of a Semiconducting ZnFe2O4 Chemiresistor
No full textA semiconducting metal oxide (SMO) chemiresistor (ZnFe2O4) is used for discriminating two isomeric volatile organic compounds (VOCs), namely 1‐ and 2‐propanol. The transient current of the SMO chemiresistor is correlated with the aerobic oxidation of organic vapors on its surface. The changes in transient current of the ZnFe2O4 chemiresistor are measured at different temperatures (260–320 °C) for detecting equal concentrations (200 ppm) of the two structural isomers of propanol. The transient current of ZnFe2O4 reflects a faster oxidation of 2‐propanol than 1‐propanol on the surface. First‐principles calculations and kinetic studies on the interaction of 1‐ and 2‐propanol over ZnFe2O4 provide further insight in support of the experimental evidence. The calculations predict more spontaneous adsorption of 2‐propanol on the (111) surface of ZnFe2O4 than 1‐propanol. Kinetic parameters for the oxidation of isomeric vapors are estimated by modelling the transient current of ZnFe2O4 using the Langmuir‐Hinshelwood reaction mechanism. The faster oxidation of 2‐propanol and comparatively lower activation energy for the respective process over ZnFe2O4 is justified in accordance to the chemical structures of vapors. The findings have strong implications in exploring a new technique for discriminating isomeric VOCs, which is significant for environmental monitoring and medical applications
Experimental and numerical investigation on the mechanical characteristics of polyethylenimine functionalized graphene oxide incorporated woven carbon fibre/epoxy composites
No full textThe synergistic effects of polyethyleneimine functionalized graphene oxide (PEI-FGO) on the static and dynamic mechanical properties of the carbon fibre reinforced epoxy composites were investigated in detail. The functional groups of PEI-FGO, especially the single bondNH2, experienced strong molecular interaction with the epoxy resin, and increased the load carrying capacity of the matrix, and the corresponding overall mechanical strength of the composites. The tensile and flexural strength of the 0.3 wt% PEI-FGO incorporated CF/epoxy composites was improved by ∼ ((58–62) and (65–70)) %, respectively as compared to the base CF/epoxy composites. The numerical analysis via Finite Element Method of the prepared composites was carried out to validate the experimental results. The numerical models showed linear behavior in the stress-strain diagram, whereas the experimental results expressed non-linear behavior, due to the fibre-matrix de-bonding. The effects of temperature and frequency on the dynamic mechanical properties of the prepared composites were meticulously studied. The broadening of the tan δ curve with increasing frequency also signified that PEI-FGO affects the molecular motions of the epoxy network
Polypyrrole nanoparticles-based soft actuator for artificial muscle applications
No full textCurrently, a straightforward fabrication technique for the development of soft actuators to explore their potential in robotic applications using environmentally compatible raw materials represents an important challenge. A conventional conducting polymer, such as polypyrrole (PPy), shows promising conductivity for such applications. This study presents the synthesis of PPy/polyvinyl alcohol (PPy/PVA)-based ion exchange polymer films containing PEDOT:PSS/SWNT/IL electrodes that undergo conformational changes in response to the applied voltage. Four types of ionic polymer actuator films with different sizes of PPy nanoparticles were fabricated to investigate the size-dependent electromechanical actuation performance. The aim of this study is to design and develop a stable, flexible, and reliable film actuator for robotic applications. Scanning electron microscopy and transmittance electron microscopy were performed to observe the surface morphology and detailed structure of the fabricated actuator films. The current density and ionic conductivity are demonstrated by the cyclic voltammogram and linear sweep voltammogram, respectively. The enhanced values of the water uptake, ion exchange capacity and ionic conductivity of the PPy/PVA polymer composite films enhanced the electrical properties and the tip deflection performance as compared to those of the other reported expensive perfluorinated polymer-based membrane actuators. A two finger-based micro gripping device was also developed, in which both the fingers were made up of the O-PPy/PVA/EL-based ion exchange polymer films. This mechanically stable and flexible film actuator fabricated via a synergistic combination of PPy/PVA composition containing PEDOT:PSS/SWNT/IL electrode surfaces possesses a substantial potential as an actuator material for micro robotic applications
Removing toxic contaminants from groundwater by graphene oxide nanocomposite in a membrane module under response surface optimization
No full textA novel graphene oxide nanocomposite was investigated in a flat membrane module with cross-flow pattern for decontamination of water on optimization of the operating conditions. Response surface optimization methodology was followed in arriving at the best operating conditions. The best module performance in terms of flux and rejection was obtained at the optimum set of operating conditions comprising a pH of 8.0, operating pressure of 14 bars and an hourly cross-flow of 800 L. At the end of a 96-h run, the observed drop in flux was a negligible 3.4%. On rinsing and backwashing at the end of this period, the net drop could be limited to within 2%. The module succeeded in selectively removing 98.5% of arsenic, 96.7% of fluoride, 96–97% of iron and suspended solids from contaminated groundwater while permeating more than 79–81% of the useful calcium and 87–90% of magnesium minerals as desired in potable water. The study shows that if run under properly optimized conditions, a flat membrane module with cross-flow pattern and equipped with the graphene oxide nanocomposite can be a potential technology in producing healthy, tasty and non-toxic drinking water from contaminated groundwater even in the remote areas