Electrochemical synthesis and characterization of self-supported polypyrrole-DBS-MWCNT electrodes

The electrochemical conditions (electrolyte potential window, monomeric oxidation) for the synthesis of polypyrrole- dodecylbenzenesulfonate-multiwalled carbon nanotube (PPy-DBS-MWCNT) composite were determined. Thick PPy-DBS-MWNT films were electrogenerated and peeled off from the working electrode. Selfsupported PPy-DBS-MWCNT electrodes were fabricated. The morphology of the film was analyzed by SEM. Self-supported electrodes were characterized by potential cycling and by consecutive square potential waves in NaClO4 aqueous solution with different cathodic potential limits. Higher reduced structures (the current never drops to zero) are obtained and analyzed fromvoltammetric responses until rising cathodic potential limits (up to−5 V). For high cathodic potentials (N−1 V) a slow hydrogen evolution coexists with the film reduction, as revealed from coulovoltammetric (charge-potential) responses, and the reduction rate decreaseswithout significant polymeric degradation. Degradation of the material electroactivity in NaClO4 is initiated by anodic overpotentials beyond 1.2 V. Both, oxidation and reduction chronoamperometric responses prove the presence of nucleation processes, most significant during oxidation. Chronocoulometric responses illustrate slower oxidation rates from deeper reduced initial states. The electrochemical responses are explained by reaction-driven conformational and structural changes that are clarified by the coulovoltammetric response

Use of Fiberoptic Intubation Simulation to Enhance Skill and Confidence Among Anesthesia Providers

Abstract Background: The purpose of this study was to describe the usefulness of a video-recorded low-fidelity Fiber Optic (FO) intubation simulation and its effect on anesthesia providers’ confidence and skill in performing FO intubation. Method: The study was conducted during the 2019 IANA Airway Workshop using a post-test only study design. All participants who volunteered to participate in the simulation were asked to watch a video-recorded instruction on FO intubation. Immediately after viewing the video, the participants completed a hands-on simulation while the researchers recorded their FO intubation times. Participants were allowed up to three recorded attempts. Results: Fifty-eight participants completed the hands-on simulation and the post-simulation questionnaires. Results showed an improvement in skill as evidenced by faster mean FO intubation times for each of the three attempts (27.34 sec, 24.99 sec, and 16.13 sec). The FO simulation was found to be effective as demonstrated by participants rating the simulation as both useful (M = 3.73; SD = -0.77; Range = 1 to 4) and instilling a sense of confidence (M = 3.58; SD = 0.81; Range = 1 to 4). Conclusion: The simulation enhanced anesthesia providers’ skill and confidence in FO intubation and was found useful by the participants. Key Words: Low-fidelity simulation, fiberoptic intubation, anesthesia providers, instructional video, airway workshop

Essence of enterprise crisis and reasons of its appearance

The effect of the electrolyte concentration (NaCl aqueous electrolyte) on the dimensional variations of films of polypyrrole doped with dodecylbenzenesulfonate PPy(DBS) on Pt and Au wires was studied. Any parallel reaction that occurs during the redox polymeric reaction that drives the mechanical actuation, as detected from the coulovoltammetric responses, was avoided by using Pt wires as substrate and controlling the potential limits, thus significantly increasing the actuator lifetime. The NaCl concentration of the electrolyte, when studied by cyclic voltammetry or chronoamperometry, has a strong effect on the performance as well. A maximum expansion was achieved in 0.3 M aqueous solution. The consumed oxidation and reduction charges control the fully reversible dimensional variations: PPy(DBS) films are faradaic polymeric motors. Parallel to the faradaic exchange of the cations, osmotic, electrophoretic, and structural changes play an important role for the water exchange and volume change of PPy(DBS)

Carbon and oxygen in HII regions of the Magellanic Clouds: abundance discrepancy and chemical evolution

We present C and O abundances in the Magellanic Clouds derived from deep spectra of HII regions. The data have been taken with the Ultraviolet-Visual Echelle Spectrograph at the 8.2-m VLT. The sample comprises 5 HII regions in the Large Magellanic Cloud (LMC) and 4 in the Small Magellanic Cloud (SMC). We measure pure recombination lines (RLs) of CII and OII in all the objects, permitting to derive the abundance discrepancy factors (ADFs) for O^2+, as well as their O/H, C/H and C/O ratios. We compare the ADFs with those of other HII regions in different galaxies. The results suggest a possible metallicity dependence of the ADF for the low-metallicity objects, but more uncertain for high-metallicity objects. We compare nebular and B-type stellar abundances and we find that the stellar abundances agree better with the nebular ones derived from collisionally excited lines (CELs). Comparing these results with other galaxies we observe that stellar abundances seem to agree better with the nebular ones derived from CELs in low-metallicity environments and from RLs in high-metallicity environments. The C/H, O/H and C/O ratios show almost flat radial gradients, in contrast with the spiral galaxies where such gradients are negative. We explore the chemical evolution analysing C/O vs. O/H and comparing with the results of HII regions in other galaxies. The LMC seems to show a similar chemical evolution to the external zones of small spiral galaxies and the SMC behaves as a typical star-forming dwarf galaxy.Comment: Accepted for publication in MNRAS, 17 pages, 11 figures, 8 table