Facile single-step synthesis of nitrogen-doped reduced graphene oxide-Mn(3)O(4) hybrid functional material for the electrocatalytic reduction of oxygen.

Development of efficient electrocatalyst based on non-precious metal that favors the four-electron pathway for the reduction of oxygen in alkaline fuel cell is a challenging task. Herein, we demonstrate a new facile route for the synthesis of hybrid functional electrocatalyst based on nitrogen-doped reduced graphene oxide (N-rGO) and Mn3O4 with pronounced electrocatalytic activity towards oxygen reduction reaction (ORR) in alkaline solution. The synthesis involves one-step in situ reduction of both graphene oxide (GO) and Mn(VII), growth of Mn3O4 nanocrystals and nitrogen doping onto the carbon framework using a single reducing agent, hydrazine. The X-ray photoelectron (XPS), Raman and FTIR spectral, and X-ray diffraction measurements confirm the reduction of GO and growth of nanosized Mn3O4. The XPS profile reveals that N-rGO has pyridinic (40%), pyrrolic (53%), and pyridine N oxide (7%) types of nitrogen. The Mn3O4 nanoparticles are single crystalline and randomly distributed over the wrinkled N-rGO sheets. The hybrid material has excellent ORR activity and it favors the 4-electron pathway for the reduction of oxygen. The electrocatalytic performance of the hybrid catalyst is superior to the N-rGO, free Mn3O4 and their physical mixture. The hybrid material shows an onset potential of -0.075 V, which is 60-225 mV less negative than that of the other catalyst tested. It has excellent methanol tolerance and high durability. The catalytic current density achieved with the hybrid material at 0.1 mg cm(-2) is almost equivalent to that of the commercial Pt/C (10%). The synergistic effect of N-rGO and Mn3O4 enhances the overall performance of the hybrid catalyst. The nitrogen in N-rGO is considered to be at the interface to bridge the rGO framework and Mn3O4 nanoparticles and facilitates the electron transfer.

A comparative study between Truview(PCD) laryngoscope and Macintosh laryngoscope in viewing glottic opening and ease of intubation: A crossover study.

BACKGROUND: Truview(PCD) laryngoscope is specially designed to aid positioning of the endotracheal tube as well as to record entry of the tube into glottis. Aim of the study is to compare the view of glottic opening and ease of intubation between Truview(PCD) laryngoscope and Macintosh laryngoscope in patients undergoing general anesthesia (GA). METHODOLOGY: Two hundred patients undergoing elective surgery, under GA were randomized into two groups, Group TV and Group ML. In Group TV, Trueview(PCD) laryngoscope was used initially to visualize the vocal cords for Cormack and Lehane grading (CLG) and to spray the vocal cords with 10% lignocaine. Then the patient was ventilated for 1 min and Macintosh laryngoscope was used to visualize the vocal cords for CLG and proceed with intubation. In Group ML, Macintosh laryngoscope was used initially and later Truview(PCD) laryngoscope. Time to intubation, CLG, number of attempts and hemodynamic parameters were recorded. RESULTS: Ninety-six and 89 patients had CLG1 visualization when Truview(PCD) laryngoscope was used as 1(st) and 2(nd) device respectively compared to 41 and 68 with Macintosh laryngoscope (P = 0.00). Four patients had CLG 4 visualization with Macintosh laryngoscope that turned out to be grade II visualization with Truview(PCD) laryngoscope (P = 0.00). Mean time taken for intubation with Truview(PCD) and Macintosh laryngoscope was 21.10 ± 5.64 s and 15.79 ± 2.76 s respectively (P = 0.00). CONCLUSION: Better visualization with lesser CLG was found with Truview(PCD) laryngoscope but it took longer time for intubation than Macintosh laryngoscope. The hemodynamic response to intubation was significantly less with the use of Truview(PCD) laryngoscope when compared to that of Macintosh laryngoscope.

Fabrication of multi-structure nanocarbons from carbon xerogel: a unique scaffold towards bio-imaging.

A novel route has been developed to fabricate different carbon nanostructures having individual morphology of carbon nanoparticles: nanofullerene, nanocube, nanoleaf and porous nanorods, through the combustion of carbon xerogel with nitric acid. These fabricated nanostructures exhibited bright green fluorescence under the exposure of UV light.

Synthesis, functionalization and bioimaging applications of highly fluorescent carbon nanoparticles.

Highly fluorescent crystalline carbon nanoparticles (CNPs) have been synthesized by one step microwave irradiation of sucrose with phosphoric acid at 100 W for 3 min 40 s. This method is very simple, rapid and economical and hence can be used for large scale applications. The average particle sizes are 3 to 10 nm and they emit bright green fluorescence under the irradiation of UV-light. Therefore, the particles can be used as a unique material for bioimaging as well as drug delivery. To further increase the fluorescence property of the synthetic carbon nanoparticles we simply functionalized them by using different organic dyes, such as fluorescein, rhodamine B and α-naphthylamine; the maximum fluorescence intensity was observed for the particles functionalized with fluorescein. It is very interesting to note that all of those compounds show maximum fluorescence intensity at 225 nm excitation wavelength and for any excitation wavelength the peak positions are exactly same the position as that of CNPs itself, which is completely different from the individual precursors (dyes). All of the above compounds, including CNPs, have also been successfully introduced into the erythrocyte enriched fraction of healthy human blood cells with minimum cytotoxicity.