Boosting the electrocatalytic activity of Pd/C by Cu alloying: Insight on Pd/Cu composition and reaction pathway.

Tuning composition of Pd-based bimetallic electrocatalysts of high stability and durability is of great importance in energy-related reactions. This study reports the remarkable electrocatalytic performance of carbon-supported bimetallic Pd-Cu alloy nanoparticles (NPs) towards formic acid oxidation (FAO) and oxygen reduction reaction (ORR). Among various bimetallic compositions, Pd3Cu/C alloy NPs exhibits the best FAO and ORR activity. During FAO reaction, Pd3Cu/C alloy NPs exhibits a peak with a current density of 28.33 mA cm-2 and a potential of 0.2 V (vs. Ag/AgCl) which is higher than that of the other PdCu compositions and standard 20 wt% Pd/C catalyst. Meanwhile, the onset potential (-0.09 V), half-wave potential (-0.18 V), limiting current density at 1600 rpm (-4.9 mA cm-2) and Tafel slope (64 mV dec-1) values of Pd3Cu/C alloy NPs validate its superiority over the conventional 20 wt% Pt/C catalyst for ORR. Experimental and DFT studies have confirmed that the enhanced activity can be attributed to the electronic effect that arises after Cu alloying which causes a downshift of Pd d-band center and structural effect that produces highly dispersed NPs over the carbon matrix with high electrochemically active surface area.

Cu-Based Nanoparticles as Emerging Environmental Catalysts.

This account provides an overview of current research activities on nanoparticles containing the earth-abundant and inexpensive element copper (Cu) and Cu-based nanoparticles, especially in the field of environmental catalysis. The different synthetic strategies with possible modification of the chemical/ physical properties of these nanoparticles using such strategies and/or conditions to improve catalytic activity are presented. The design and development of support and/or bimetallic systems (e. g., alloys, intermetallic, etc.) are also included. Herein, we report synthetic approaches of Cu and Cu-based nanoparticles (monometallic copper, bimetallic copper and copper (II) oxide nanoparticles/nanostructures) and impregnation of such nanoparticles onto support material (e. g., Co3 O4 nanostructure), along with their applications as environmental catalyst for various oxidation and reduction reactions. Finally, this account provides necessary advances and perspectives of Cu-based nanoparticles in the environmental catalysis.

Gold­manganese oxide nanocomposite suppresses hypoxia and augments pro-inflammatory cytokines in tumor associated macrophages.

The tumor microenvironment, essentially hypoxic, is sustained by the hypoxia inducing factor (HIF), released from the pro-tumorigenic tumor associated macrophages (TAMs), functionally identical to the M2 phenotype macrophages. Stability of HIF mainly depends on molecular oxygen and an iron-dependent enzyme prolyl hydroxylase, while its activity may be inhibited by high levels of reactive oxygen species and nitric oxide. The present work showcases a novel approach utilizing the anti-tumorigenic potential of a gold-manganese oxide nanocomposite material in the tumor microenvironment that affects tumor hypoxia, exploring the possibility of restoring the immunoregulatory nature of TAMs from their pro-tumorigenic state. Along with the biochemical markers, ELISA and FACS analyses have also confirmed the potential of these nanoparticles in reverting back the M2 phenotype of TAMs to their classically activated M1 phenotype.

Enhanced catalytic activity of CuPd alloy nanoparticles towards reduction of nitroaromatics and hexavalent chromium.

The present work reports a surfactant-free, economically feasible chemical route to synthesize bimetallic CuPd alloy nanoparticles under hydrothermal condition. The structural and morphological characterizations of the nanoparticles are carried out by XRD, SEM/EDX, TEM, XPS and BET surface area analyses. The synthetic strategy comprises of 9:1 molar composition of Cu2+ and Pd2+ salt in the aqueous solution. The size of the nanoparticles isca. 3-4nmwith very notable specific surface area of 298m2g-1. The synthesized nanoparticles exhibit excellent catalytic performance towards the aqueous phase reduction of 4-nitrophenol and 4-nitroaniline in the presence of NaBH4 as a reducing agent. Furthermore the CuPd alloy nanoparticles also demonstrate remarkable activity towards reductive conversion of toxic Cr(VI) to less toxic Cr(III) at room temperature. Bimetallic CuPd alloy nanoparticles are catalytically more active and exhibit good recyclability in comparison to the monometallic Cu and Pd due to synergistic effect.

Bactericidal activity of selected medicinal plants against multidrug resistant bacterial strains from clinical isolates.

OBJECTIVE: To investigate the antibacterial effect of Curcuma longa (C. longa), Zingiber officinale (Z. officinale) and Tinospora cordifolia (T. cordifolia) against Staphylococcus aureus, Pseudomonas aeruginosa, Klebsiella pneumoniae, Escherichia coli, Bacillus subtilis and Proteus mirabilis of clinical origin. METHODS: The antimicrobial efficacy of said medicinal plants and establishment of multidrug resistant character of these bacteria were carried out using disc diffusion, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) methods. RESULTS: The results of MIC and MBC showed that these clinical bacterial isolates were phenotypically multidrug resistant against standard antibiotics (>500 µg/mL). Compared to standard antibiotics, C. longa, Z. officinale and T. cordifolia were more effective in killing these microbes as evident from MIC and MBC values (5 to 125 µg/mL). Moreover, C. longa had highest antibacterial efficacy compared to Z. officinale and T. cordifolia. CONCLUSIONS: The result thus obtained suggests that bioactive principles of these plants can be used particularly against these multidrug resistant bacteria of clinical origin.