The inadvertent discharge of industrial effluents, mainly textile, contributes to the complex contamination load in water bodies. Textile dyes are the critical effluents and recalcitrant to traditional remediation procedures. Therefore, energy viable and environment friendly solutions are needed. In this study, we have synthesized zinc oxide nanorods (NRs) at various temperatures using modified thermal decomposition and evaluated its photocatalytic activities. Field effect scanning electron microscopy has confirmed rod-like morphology till T_S = 500 °C and spherical morphology from T_S = 600 °C onward. Photoluminescence spectra have shown a prominent defect peak in the synthesized ZnO, except for the NRs synthesized at 300 °C. Synthesized ZnO NRs and NPs have been employed to degrade crystal violet (CV) and congo red (CR) dyes. ZnO NRs have shown impressive photocatalytic performance with faster treatment time as compared to the earlier reports. Synthesis parameters are well correlated with the observed high efficiency and the band gap tailoring. Based on our findings, for the first time, we have proposed (i) defect model correlating synthesis parameters with defect states, (ii) systematic correlation of defect states with photocatalytic efficiency, and (iii) ZnO nanorods synthesized at 300 °C via an improved synthesis method as a promising photocatalytic solution to degrade the CV and CR dyes in contaminated water.

Medical devices such as Central Venous Catheters (CVCs), are routinely used in intensive and critical care settings. In the present scenario, incidences of Catheter-Related Blood Stream Infections (CRBSIs) pose a serious challenge. Despite considerable advancements in the antimicrobial therapy and material design of CVCs, clinicians continue to struggle with infection-related complications. These complications are often due colonization of bacteria on the surface of the medical devices, termed as biofilms, leading to infections. Biofilm formation is recognized as a critical virulence trait rendering infections chronic and difficult to treat even with 1,000x, the minimum inhibitory concentration (MIC) of antibiotics. Therefore, non-antibiotic-based solutions that prevent bacterial adhesion on medical devices are warranted. In our study, we report a novel and simple method to synthesize zinc oxide (ZnO) nanoparticles using ethanolic plant extracts of Eupatorium odoratum. We investigated its physio-chemical characteristics using Field Emission- Scanning Electron Microscopy and Energy dispersive X-Ray analysis, X-Ray Diffraction (XRD), Photoluminescence Spectroscopy, UV-Visible and Diffuse Reflectance spectroscopy, and Dynamic Light Scattering characterization methods. Hexagonal phase with wurtzite structure was confirmed using XRD with particle size of ∼50 nm. ZnO nanoparticles showed a band gap 3.25 eV. Photoluminescence spectra showed prominent peak corresponding to defects formed in the synthesized ZnO nanoparticles. Clinically relevant bacterial strains, viz., Proteus aeruginosa PAO1, Escherichia coli MTCC 119 and Staphylococcus aureus MTCC 7443 were treated with different concentrations of ZnO NPs. A concentration dependent increase in killing efficacy was observed with 99.99% killing at 500 μg/mL. Further, we coated the commercial CVCs using green synthesized ZnO NPs and evaluated it is in vitro antibiofilm efficacy using previously optimized in situ continuous flow model. The hydrophilic functionalized interface of CVC prevents biofilm formation by P. aeruginosa, E. coli and S. aureus. Based on our findings, we propose ZnO nanoparticles as a promising non-antibiotic-based preventive solutions to reduce the risk of central venous catheter-associated infections.

Combined scanning tunneling microscopy, spectroscopy, and local barrier height (LBH) studies show that low-temperature-cleaved optimally doped Ba(Fe_1–xCo_x)₂As₂ crystals with x = 0.06, with T_c = 22 K, have complicated morphologies. Although the cleavage surface and hence the morphologies are variable, the superconducting gap maps show the same gap widths and nanometer size inhomogeneities irrelevant to the morphology. Based on the spectroscopy and LBH maps, the bright patches and dark stripes in the morphologies are identified as Ba- and As-dominated surface terminations, respectively. Magnetic impurities, possibly due to Co or Fe atoms, are believed to create local in-gap state and, in addition, suppress the superconducting coherence peaks. This study will clarify the confusion on the cleavage surface terminations of the Fe-based superconductors and its relation with the electronic structures.