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An intimate physical mixture of graphene oxide (GO) and semiconducting organic molecules like bromophenathrene (BrPh) and bromopyrene (BrPy) was prepared by using a ball milling technique. The structural, microstructural, physical and chemical properties of the mixtures (20 wt% of GO) were analyzed by X-ray diffraction, SEM, FT-IR, TGA and TCSPC studies. Furthermore, the electrochemical properties like AC electrical conductivity, transient photocurrent response (PCTR) and open circuit voltage (OCVD) of the samples were analyzed. It has been observed from TCSPC and OCVD measurements that 20 wt% of GO in the semiconductor composite leads to an enhanced life-time of photo-generated charge carriers. The physical mixture composites exhibit a higher photocurrent than pure BrPh and BrPy.

Hematite (α-Fe2O3) forms iron oxide nanoparticles (NPs) which are thermally stable and have various electrochemical and optochemical applications. Due to their wide applicability, the present work was designed to form the hematite phase of iron oxide (αFe2O3NPs) NPs prepared via a solution process. Their cytological performance was checked with C2C12 cells. The crystalline property of the NPs was examined with X-ray diffraction patterns (XRD) and it was found that the size of the particles formed ranged from 12 to 15 nm. Structural information was also identified via field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM), which again confirmed that the size of each NP is about 12–15 nm. Surface topographical analysis was done via atomic force microscopy (AFM), which reveals that the size of the distance between two particles is in the range of 12 ± 3 nm. The C2C12 cells were cultured in a humidified environment with 5% CO2 and were checked via a microscope. The αFe2O3NPs were used for cytotoxic evaluation against C2C12 cells. A MTT (3-(4,5-dimethyl thiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay was utilized to check the viability of cells in a dose-dependent (100 ng mL−1, 500 ng mL−1 or 1000 ng mL−1) manner. The morphology of the cells under the influence of αFe2O3NPs for live and dead cells in a wet environment was confirmed via confocal laser scanning microscopy (CLSM). The apoptosis caused due to the αFe2O3NPs was evaluated in presence of caspases 3/7 with GAPDH genes, which confirmed the upregulation that is responsible in caspase 3/7 genes, with treatment of C2C12 at low (500 ng mL−1) and high (1000 ng mL−1) doses of αFe2O3NPs. Analytical studies were also performed to authenticate the obtained data for αFe2O3NPs using parameters such as precision, accuracy, linearity, limits of detection (LOD) and limit of quantitation (LOQ), quantitative recoveries and relative standard deviation (RSD). The analyses play a significant role in investigating the large effect of αFe2O3NPs on C2C12 cells.

Herein, we report the covalent functionalization of graphene oxide (GO) through ''click'' reaction and its applications towards ammonia sensing. This inimitable method of covalent functionalization involves linking GO with azide moiety and click coupling of different derivatives of aryl propargyl ether, which enhances the sensitivity towards ammonia. The functionalized GO were characterized using NMR, XRD, SEM, FT-IR, Raman, UV-Vis, TGA and DSC. Compared to pristine GO, the GO functionalized with Ar samples (GO-Ar) exhibit excellent room temperature ammonia sensing properties with good response/recovery characteristics. It has been observed that 2,3-difluoro and 2,3,4-trifluoro substituted aryl propargyl ether functionalized GO (GO-Ar2 and GO-Ar3) shows superior ammonia sensing with response/recovery of 63%/∼90% and 60%/100%, respectively at 20 ppm. The GO-Ar3 exhibits high sensitivity towards ammonia at 20-100 ppm. Computational studies supports the high sensitivity of GO-Ar towards ammonia due to its high adsorption energy.

The present paper describes a systematic study of bacterial growth measured and analysed via UV-visible spectroscopy, which reveals a strong dependence on pH. The morphology of the zinc oxide (ZnO) nanostructures (from sheets to flowers) varies with respect to change in pH and hence their different abilities to inhibit the bacterial (E. coli, S. aureus and K. pneumoniae) densities. The solution of zinc acetate dihydrate (Zn(CH3COO)2·2H2O) was optimized by the addition of NaOH and HCl to obtain various pH values, ranging from pH 7 to 12. The optimized (pH 7, 10 and 12) solutions of zinc acetate dihydrate were further refluxed to obtain the different morphologies, and subsequently qualitative and quantitative determinations were studied. Absorption spectra of the resulting solutions were recorded at desired pH values, and all measurements were obtained at 600 nm with respect to corresponding control solution or blank. The linearity of the proposed method was evaluated at five concentration levels in the range from 0.5 to 2.0 μg mL−1. Minute quantities of the different morphological nanostructures were used to determine the analytical parameters, such as correlation coefficient (r2 = 0.9995, 0.9998, 0.9990), limit of detection (LOD, 0.053, 0.027 and 0.072 μg mL−1), limit of quantitation (LOQ, 0.016, 0.083 and 0.220 μg mL−1), respectively. Relative standard deviation and quantitative recoveries (RSD%) range from 0.113 to 1.58% and 98.66–100.88%. The morphologies of bacteria (E. coli, S. aureus and K. pneumoniae) and their interactions with synthesized ZnO nanostructures were analysed with Bio-TEM. The study suggests that the grown ZnO nanostructures with variable morphologies exhibit good accuracy and precision, revealed by statistical parameters and recovery data.

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The present paper describes a detailed investigation of the nature of the order–disorder transition in the Nd2−yHoyZr2O7 system, over the entire composition range (0.0 ≤ y ≤ 2.0), using a combination of diffraction and spectroscopic analysis techniques. The complete series of solid solutions has been prepared by the gel combustion technique followed by high temperature sintering. Detailed structural characterization of the prepared samples using X-ray diffraction studies confirmed their single-phase solid solution formation throughout the series, as well as identifying the transformation of the system from an ordered pyrochlore structure (0.0 ≤ y ≤ 0.8) to a disordered fluorite-type structure (0.8 < y ≤ 2.0). Micro-Raman studies further supported the structural information. Micro-structural studies by SEM revealed dense products with uniform grain distribution in these materials. Comprehensive studies were performed to investigate the ionic conductivity behavior of these solid solutions in correlation with the structural transformations using AC impedance spectroscopy. A detailed analysis of ionic conductivity and related parameters, such as activation energies, etc. corresponding to individual conduction mechanisms such as bulk and grain boundary conduction, clearly correlated the effect of structural transformation on these charge transport properties. The composition Nd1.2Ho0.8Zr2O7 with the pyrochlore structure has been found to show the highest ionic conductivity in the entire series, which has been attributed to a combined effect of increasing carrier concentration and their preferred movement through an ordered array of vacant anion sites.