Synthesis,characterization and use of iron oxide nano particles for antibacterial activity

In this decade, the use of nano particles (NPs) against bacterial growth is increasing day by day due to remarkable alternative properties compared to molecular antibiotics. Thus, the use of iron oxide nanoparticles (IONPs) has proven one of the most important transition metals oxide‐based remedy in nanotechnological advances and biological applications due to enriched biocompatibility of iron. In this study synthesis of IONPs was carried out via co‐precipitation method. The crystallographic morphology of the synthesized particles was studied via X‐ray diffraction which revealed cubic structure of the particles, whereas, the spinal shaped morphology of the prepared NPs was confirmed from scanning electron microscopy. Likewise, the presence of the major elements in the sample was determined through energy dispersive X‐ray analysis characterization. Bactericidal effect of the NPs was assessed at pre‐defined concentrations (50 and 100 μg/ml) against Gram +ve bacteria Staphylococcus aureus, Gram ?ve bacteria Shigella dysentry and Escherichia coli . Bacterial strains, which demonstrate the potential of NPs. The purpose of this study was assessing the structure of the synthesized NPs for protective effect against harmful bacterial activity.     

Numerical study of mixed convection nanofluid in an annulus enclosure between outer rotating cylinder and inner corrugation cylinder

Numerical investigations are presented for mixed convection problems in a concentric inner sinusoidal cylinder and an outer rotating circular cylinder, which were kept at constant hot and cold temperatures, respectively. The free space between the cylinders and the enclosure walls was filled with a water‐Cu nanofluid. The governing equations are formulated for velocity, pressure, and temperature formulation and are modeled in COMSOL5.2a, a partial differential equation solver based on the Galerkin finite element method. The governing parameters considered are the solid volume fraction, [0, 0.02, 0.04, and 0.06], Re (1, 25, 100, 200, and 300), and Ra (less than 10⁴), and the inner cylinder corrugation frequencies varied from (N = 3, 6, and 9). According to the calculations, the Reynolds number, the Rayleigh number, the nanoparticle volume fraction, and the number of corrugations play an important role of forming the stream and isothermal lines, the local and the average Nusselt number inside the annulus enclosure. The average Nusselt number decreases with increasing Reynolds number and the number of corrugations, while it increases as the Rayleigh number and the volume fraction increase.     

Polyacrylonitrile–poly(1-vinyl pyrrolidone-co-vinyl acetate) blend based gel polymer electrolytes incorporated with sodium iodide salt for dye-sensitized solar cell applications

New gel polymer electrolytes (GPEs) were prepared via the blending of a polyacrylonitrile polymer and a poly(1-vinyl pyrrolidone-co-vinyl acetate) copolymer. The sodium iodide (NaI) salt concentration was varied for each GPE sample. From ionic conductivity (σ) studies, we observed that the sample with a 40 wt % NaI salt content (N40) showed the highest σ of 3.54 × 10⁻³ ± 0.05 S/cm at room temperature, and all of the GPE samples obeyed Arrhenius behavior. The dielectric properties of the GPE samples were also analyzed to study the electrical polarization of the materials. The developed GPE samples were also characterized with X-ray diffraction and Fourier transform infrared spectroscopy. We also then used the developed GPE samples for the fabrication of dye-sensitized solar cells by sandwiching them between a photoanode and Pt counter electrode for photovoltaic studies. The highest photovoltaic performance was achieved by N40, with an efficiency of 3.04%. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47810.     

An Innovative Approach to the Synthesis of PMMA/PEG/Nanobifiller Filled Nanocomposites with Enhanced Mechanical and Thermal Properties

A facile route was adopted to blend the matrix. The PMMA/PEG blend was reinforced with three types of nanofillers, i.e., pristine MWCNT (P-CNT), amine functionalized MWCNT (PDA-EA-CNT) and nanobifiller i.e. nanodiamond functional MWCNT (PDA-EA-CNT-ND) to yield three different types of nanocomposites i.e. PMMA/PEG/P-CNT, PMMA/PEG/PDA-EA-CNT and PMMA/PEG/PDA-EA-CNT-ND. These nanocomposites were reinforced with nanofiller loading (1 wt. %, 3 wt. %, 5 wt. %, 10 wt. %, 30 wt. % and 50 wt. %) by solution casting method. Structure of composite and nanofillers was confirmed by FTIR. FESEM imaging revealed that nanocomposites have micro porous morphology. At high magnification, distribution of functionalized CNT/ND appears to be protruding out of the polymeric matrix. The TGA result suggests that the thermal stability of the nanocomposites was enhanced in comparison to PMMA due to grafting of filler molecules with PMMA/PEG macromolecules. The DTG results showed that the bifiller nanocomposites (PMMA/PEG/PDA-EA-CNT-ND) exhibited improved thermal stability with T_max (431^°C) as compared to P-CNT and amine functionalized CNT (PMMA/PEG/PDA-EA-CNT) with T_max of 395^°C and 418^°C respectively. XRD results showed fine interaction between filler and the polymeric matrix. As the filler loading was increased the composites showed pronounced XRD peak at 25.9^°, corresponding to (002) reflection of nanotubes. Significant improvement in the mechanical properties of composites was recorded with the reinforcement of fillers as compared to the neat matrix. The most significant improvement in tensile strength and elastic modulus was observed for the bifiller nanocomposites with 5 wt. % PDA-EA-CNT-ND. They showed a tensile strength and elastic modulus of 29.9 MPa and 1474.31 MPa respectively as compared to amine functionalized CNT with tensile strength (25.7) and elastic modulus (1466.99 MPa)and P-CNT with tensile strength(25 MPa) and elastic modulus (1155.75 MPa).     

Synthesis and Characterization of Hetero-metallic Oxides-Reduced Graphene Oxide Nanocomposites for Photocatalytic Applications

A new AgO.CuO.WO₃/rGO nanocomposite was designed for the investigation of the degradation ability of the hybrid material under visible light irradiation. The AgO, CuO, WO₃ NPs, and AgO.CuO.WO₃ hetero-metallic oxides were fabricated via the chemical co-precipitation method. The crystallite sizes and phase analyses were investigated by recording X-ray diffraction patterns. The crystallite sizes of three metal oxides in the AgO.CuO.WO₃ hetero metal oxide were 16.7, 15.9, and 16.9 nm, respectively. The FESEM images at various magnifications were probed to study the morphology of synthesized materials. The micrographs of hetero-metallic oxides AgO.CuO.WO₃ exposed that three metal oxides merged like small particles and gives a large bulbous appearance. EDX analyses confirmed the formation of required materials with high purity. FTIR data was in agreement with the literature which facilitated to ensure the purity of synthesized samples. The optical bandgap energy was calculated via the Tauc plot indicating that the blend of three metal oxides generated a new energy level in the electronic structure is suitable for photocatalysis in the presence of visible light. The bandgap energy of hetero metallic oxides was 1.25 eV which is less than individual metal oxides signifying the tuning of the bandgap. The incorporation of rGO in AgO.CuO.WO₃ hetero-metallic oxides gives a new photocatalyst for optimum photodegradation of methylene blue in minimum time. The percentage degradation via AgO.CuO.WO₃ was 87.20% in 70 min while the percentage degradation via AgO.CuO.WO₃/rGO recorded by photocatalytic experiment was 95% in 40 min. The photocatalysis data revealed that AgO.CuO.WO₃ hetero-metallic oxides-rGO nanocomposite ensured a strong potential to uptake organic dyes from water by promoting redox reactions during photocatalysis in the minimum time limit.     

Fabrication of different conductive matrix supported binary metal oxides for supercapacitors applications

Here, we have fabricated the spinel binary-metal oxide (FeCo₂O₄) via a solvent-free and cost-effective approach. The nanocomposites of the as-fabricated binary-metal spinel oxide have been prepared with three different conductive-matrices, namely r-GO, CNTs, and PANI, via ultra-sonication approach. The spinel phase and surface functionalities of the fabricated FeCo₂O₄ sample have been confirmed via XRD and FT-IR analyses, respectively. The morphological-structure and elemental composition of the fabricated samples have been probed via FESEM and EDX results. The role of added conductive-matrices in the improvement of the electrical conductivities of the fabricated nanocomposites has been investigated via I–V experiments. The electrochemical experiments, conducted in half-cell configuration, showed that FeCo₂O₄/PANI nanocomposite exhibited the highest specific capacitance (658.9 Fg^-1) than that of the remaining two nanocomposites. Furthermore, FeCo₂O₄/PANI nanocomposite exhibited excellent cyclic stability as it lost just 8.3% of its initial specific capacitance even after 3000 cyclic tests. The superior capacitive-activity of the FeCo₂O₄/PANI nanocomposite is accredited to its high conductivity, large surface area, and synergy effects between the pseudocapacitance derived from the PANI and FeCo₂O₄ nanostructure. The electrochemical and electrical measurements suggested that FeCo₂O₄/PANI nanostructure is an emerging contender for energy storage applications.