The formation of copper oxides and hydroxides from metallic copper and underpotentially deposited copper atoms on platinum nanoparticles, when it is subjected to a potential scan between the hydrogen ...evolution potential and the oxygen evolution potential in alkaline solution as a function of scan rate and the pH of the solution has been investigated. Cyclic voltammetry of bulk copper electrodes in alkaline solution reveal that oxidation proceeds in steps leading to formation of Cu2O, Cu(OH)2 and CuO on the surface as well as some soluble oxides which corroborates well with X-ray photoelectron spectroscopy (XPS) analysis. Furthermore, interesting needle like formations on copper surface was observed in a scanning electron microscope (SEM), which can explain the unusual relation between the peak current and scan rate. On the other hand, the oxidation of copper monolayer on platinum nanoparticles leads primarily to formation of Cu2O and shows the effect of nobility imparted by the underlying platinum in terms of increased potential.
We report the synthesis of a novel nanohybrid based on nickel sulfide (NiS) nanoparticles decorated reduced graphene oxide (rGO) following a facile hydrothermal approach for application as Pt-free ...counter electrode (CE) in dye sensitized solar cells (DSSC). The DSSC devices fabricated using this NiS/rGO nanohybrid film as CE showed an impressive power conversion efficiency (PCE) of 9.5% and a fill factor of about 0.78 when illuminated by AM 1.5 G simulated solar light. These values are well above those reported previously for DSSCs fabricated with Pt free CE and thus establishes the potential of the NiS/rGO nanohybrid as an excellent low-cost CE material for DSSC fabrication. The improvement in the PCE is due to improved electro-catalytic activity of the NiS/rGO nanohybrid for reduction of the triiodide caused by the synergistic effects of highly catalytic NiS nanoparticles and electrically conductive rGO.
Display omitted
•NiS/rGO nanoybrids were synthesized using a facile and cost-effective hydrothermal approach.•Uniformly distributed NiS nanoparticles with average size of 25 nm were observed on rGO sheets.•DSSCs fabricated with NiS/rGO nanoybrid counter electrode showed efficiency as high as 9.5% suggesting its potential replace Pt.•Small charge transfer resistance of the nanoybrid electrode is responsible for the high efficiency of the DSSC.
The RNA-dependent RNA polymerase (RdRp) of SARS-CoV-2 is one of the optimum targets for antiviral drug design and development. The hydroxyl groups of cytidine structures were modified with different ...aliphatic and aromatic groups to obtain 5´-O-acyl and 2´,3´-di-O-acyl derivatives, and then, these derivatives were employed in molecular modeling, antiviral prediction, molecular docking, molecular dynamics, pharmacological and POM studies. Density functional theory (DFT) at the B3LYP/6-31G++ level analyzed biochemical behavior and molecular electrostatic potential (MESP) of the modified cytidine derivatives. The antiviral parameters of the mutated derivatives revealed promising drug properties compared with those of standard antiviral drugs. Molecular docking has determined binding affinities and interactions between the cytidine derivatives and SARS-CoV-2 RdRp. The modified derivatives strongly interacted with prime Pro620 and Lys621 residues. The binding conformation and interactions stability were investigated by 200 ns of molecular dynamics simulations and predicted the compounds to firmly dock inside the RdRp binding pocket. Interestingly, the binding residues of the derivatives were revealed in high equilibrium showing an enhanced binding affinity for the molecules. Intermolecular interactions are dominated by both Van der Waals and electrostatic energies. Finally, the pharmacokinetic characterization of the optimized inhibitors confirmed the safety of derivatives due to their improved kinetic properties. The selected cytidine derivatives can be suggested as potential inhibitors against SARS-CoV-2. The POM Theory supports the hypothesis above by confirming the existence of an antiviral (Oδ--O'δ-) pharmacophore site of Hits.
Carbon-supported Pt@Cu “core−shell” nanoparticles with Pt−Cu alloy core and Pt shell have been synthesized by a galvanic displacement of Cu by Pt4+ at ambient conditions, followed by a leaching out ...of unreacted Cu on the surface by treating with 9 M H2SO4. X-ray diffraction (XRD) data indicate the formation of a Pt−Cu alloy below the Pt shell. Energy dispersive spectroscopic (EDS) analysis in a scanning electron microscope (SEM) reveals that the experimental Cu content is much lower than the initial nominal Cu content, confirming the displacement of a significant amount of Cu by Pt. X-ray photoelectron spectroscopic (XPS) studies indicate surface enrichment by Pt. Cyclic voltammetry (CV) and rotating disk electrode (RDE) measurements demonstrate an enhanced catalytic activity for the oxygen reduction reaction (ORR) for optimum Pt@Cu compositions compared to that found with commercial Pt catalyst, both per unit mass of Pt and per unit active surface area basis. Moreover, the surface area specific activities of the Pt@Cu samples increase linearly with increasing initial nominal Cu content. The increase in activity for ORR is ascribed to an electronic modification of the outer Pt shell by the Pt−Cu core.
Display omitted
•A nanohybrid of CoNi2S4 nanorods (200 nm long and 8 nm dia) embedded on RGO was synthesized.•DSSCs fabricated with CoNi2S4-RGO nanoybrid as counter electrode showed efficiency of ...9.22%.•Large surface area and good catalytic activity of the CoNi2S4-RGO nanoybrid resulted in the good DSSC performance.•The synthesized material shows good commercial prospect as counter electrode for platinum free DSSC.
Dye sensitized solar cell (DSSC) technology could become a low-cost solution for solar energy harvesting if the use of expensive dyes and Pt can be avoided. This work reports the development of a novel nanohybrid based on CoNi2S4 nanorods embedded on sheets of reduced graphene oxide (RGO), which can serve as excellent counter electrode for DSSC showing great promise to replace Pt. The structural and morphological characterisation of the nanocomposite synthesised using a simple one step hydrothermal method revealed well defined crystalline nanorods of CoNi2S4 (with length 195 nm and diameter 8.34 nm) uniformly embedded on the surfaces of the RGO sheets (~2.55 μm in size). The morphology and size of the nanorods were found to be dependent on the duration of the hydrothermal reaction. The optimized CoNi2S4/RGO nanohybrid film when used as counter electrode in DSSC, photo conversion efficiency as high as 9.22% was recorded, a value almost equal to that obtained from the DSSC fabricated with Pt as counter electrode and much higher than that with bare CoNi2S4 justifying its potential use in Pt-free DSSC. The improved performance of the electrode have been attributed to the hierarchical nanohybrid structure consisting of catalytically active 1D CoNi2S4 nanorods embedded on electrically conducting 2D RGO sheets that provides fast ion diffusion pathways, large accessible surface area and good chemical and thermal stability.
•Nickel selenide and nickel seleno-sulfide nanostructures were prepared.•Used as an electrocatalyst for the oxygen evolution reaction.•Variations in the OER performance with different Se/S mass ...ratios were observed.•Short synthesis time and catalytic stability are complimented.
Driven by industrial progress and technology expansions, the search for alternative energy resources has been an avenue of present-day research. Herein, we report the synthesis of nickel selenide (NiSe) supported by three-dimensional conducting nickel foam (NF) as a substrate via hydrothermal process for a short duration of only two-hours. Further, the addition of selenium (Se) and sulfur (S) in different ratios during the synthesis, resulted in the formation of well-ordered nickel seleno-sulfide (NiSeS/NF) nanostructures. Electron microscopy analysis revealed a unique hexagonal nanorod morphology of NiSeS grew on top of the NF, whereas NiSe/NF revealed the flake-like structures. The oxygen evolution reaction (OER) performance of these samples were studied in an alkaline (1 M KOH) environment. The addition of ‘S’ significantly enhanced the OER performance of NiSe/NF and the variation of OER performance with respect to different Se/S ratios was studied. The Se/S ratio of 0.75:0.25 delivered the best performance with a two-fold increase in overall current density with respect to NiSe/NF. At last, this work also shed light on formation of oxyanions and the conceivable mechanism after prolonged electrolysis.
Display omitted
Non-small cell lung cancer (NSCLC) is one of the most lethal malignancies accountings for nearly 80% of all lung cancer cases diagnosed and causing over one million deaths annually worldwide. The ...discovery of molecular alterations including driver mutations and gene fusions has led to innovation of numerous targeted therapies, which certainly provided an edge over the classical chemotherapeutic treatment regimens and improved survival of the patients. Despite all the breakthrough innovations, the five-year survival statistics has not improved the way it was expected, pointing the challenges and limitations of currently approved diagnostic methods and therapies. This review summarizes various innovative therapies, treatment regimens developed over the last two decades for NSCLC treatment and the current challenges and limitations in the NSCLC treatment landscape.
Ultrathin metal layer-coated particles have potential applications in various fields, especially in electrocatalysis, where catalytic activity can be increased by shell@core design. In this article, ...a synthetic method is introduced to synthesize shell@core nanoparticles, in which the selected reducing agent can be electrochemically oxidized preferentially on the core particle but not on the shell metal. Once the shell metal is deposited on the core metal, the oxidation of the reducing agent is inhibited, subsequently forming a shell@core particle with an ultrathin shell. By this method, carbon-supported shell(Pt)@core(Pd) nanoparticles with submonolayer Pt shell were synthesized using formic acid as reducing agent. Spectroscopic characterizations, X-ray photoelectron spectroscopy and energy-dispersive system, confirmed the Pt deposition. The shell@core structure of Pt@Pd was corroborated by scanning transmission electron microscopy analysis. This Pt(shell)@Pd(core) electrocatalyst was tested for electrochemical reduction of oxygen. Further, the influence of lattice parameter on the catalytic activity for oxygen reduction reaction was examined by varying the lattice parameter of Pt@Pd nanoparticles.
Roots are the primary site of interaction between plants and microorganisms. To meet food demands in changing climates, improved yields and stress resistance are increasingly important, stimulating ...efforts to identify factors that affect plant productivity. The role of bacterial endophytes that reside inside plants remains largely unexplored, because analysis of their specific functions is impeded by difficulties in cultivating most prokaryotes. Here, we present the first metagenomic approach to analyze an endophytic bacterial community resident inside roots of rice, one of the most important staple foods. Metagenome sequences were obtained from endophyte cells extracted from roots of field-grown plants. Putative functions were deduced from protein domains or similarity analyses of protein-encoding gene fragments, and allowed insights into the capacities of endophyte cells. This allowed us to predict traits and metabolic processes important for the endophytic lifestyle, suggesting that the endorhizosphere is an exclusive microhabitat requiring numerous adaptations. Prominent features included flagella, plant-polymer-degrading enzymes, protein secretion systems, iron acquisition and storage, quorum sensing, and detoxification of reactive oxygen species. Surprisingly, endophytes might be involved in the entire nitrogen cycle, as protein domains involved in N(2)-fixation, denitrification, and nitrification were detected and selected genes expressed. Our data suggest a high potential of the endophyte community for plant-growth promotion, improvement of plant stress resistance, biocontrol against pathogens, and bioremediation, regardless of their culturability.
PDF