Endergonic Hydrogenation at Ambient Conditions Using an Electrochemical Membrane Reactor.

Here, we determine how the hydrogen loading (x) of an electrochemical palladium membrane reactor (ePMR) varies with electrochemical conditions (e.g., applied current density, electrolyte concentration). We detail how x influences the thermodynamic driving force of an ePMR. These studies are accomplished by measuring the fugacity (P) of hydrogen desorbing from the palladium-hydrogen membrane and subsequently relating P to pressure-composition isotherms to determine x. We find that x increases with both applied current density and electrolyte concentration, but plateaus at a loading of x ≅ 0.92 in 1.0 M H2SO4 at -200 mA·cm-2. The validity of the fugacity measurements is supported experimentally and computationally by: (a) electrochemical hydrogen permeation studies; and (b) a palladium-hydrogen porous flow finite element analysis (FEA) model. Both (a) and (b) agree with the fugacity measurements on the following x-dependent properties of the palladium-hydrogen system during electrolysis: (i) the onset for spontaneous hydrogen desorption; (ii) the point of steady-state hydrogen loading; and (iii) the function describing hydrogen desorption between (i) and (ii). We proceed to detail how x defines the free energy of palladium-hydrogen alloy formation (ΔG(x)PdH), which is a descriptor for the thermodynamic driving force of hydrogenation at the PdHx surface of an ePMR. A maximum value ΔGPdH of 11 kJ·mol-1 is observed, suggesting that an ePMR is capable of driving endergonic hydrogenation reactions. We empirically demonstrate this capability by reducing carbon dioxide to formate (ΔGCO2/HCO2H = 3.4 kJ·mol-1) at ambient conditions and neutral pH.

Perspectives on Telemedicine from a National Study of Youth in the United States.

Introduction: Telemedicine is increasingly popular with the recent surge in use due to the COVID-19 pandemic. Despite youth status as "tech natives," limited data are available on their perspectives on telemedicine. Our study seeks to understand youth telemedicine knowledge, prior experiences, preferences for use, and the impact of COVID-19 on these perspectives. Methods: Participants in MyVoice, a national text message cohort of U.S. youth age 14-24, were sent five open-ended questions in October 2019 and October 2020. A codebook was iteratively developed by using inductive analysis. Responses were independently coded by two investigators, with discrepancies resolved by discussion or a third investigator. Results: Sixty-five percent (836/1,283) and 77% (887/1,129) of participants responded to at least 1 question in 2019 and 2020, respectively. Most youth reported awareness of telemedicine and although many have not used it, COVID-19 has increased use. Further, many are willing to try telemedicine services. Most youth noted a preference for video rather than phone visits, but they believe both to be less effective than in person. Youth also reported varied preferences on services best suited for telemedicine, with COVID-19 positively impacting their views. Discussion: Youth are aware of and willing to use telemedicine services, with many reporting use during the COVID-19 pandemic. Youth are willing to accept a wide variety of telemedicine services, though they still desire in-person options. Health systems and clinics should offer a wide range of services via telemedicine to fit the varying needs of youth both during and after the COVID-19 pandemic.

Electron Beam Transparent Boron Doped Diamond Electrodes for Combined Electrochemistry-Transmission Electron Microscopy.

The majority of carbon based transmission electron microscopy (TEM) platforms (grids) have a significant sp2 carbon component. Here, we report a top down fabrication technique for producing freestanding, robust, electron beam transparent and conductive sp3 carbon substrates from boron doped diamond (BDD) using an ion milling/polishing process. X-ray photoelectron spectroscopy and electrochemical measurements reveal the sp3 carbon character and advantageous electrochemical properties of a BDD electrode are retained during the milling process. TEM diffraction studies show a dominant (110) crystallographic orientation. Compared with conventional carbon TEM films on metal supports, the BDD-TEM electrodes offer superior thermal, mechanical and electrochemical stability properties. For the latter, no carbon loss is observed over a wide electrochemical potential range (up to 1.80 V vs RHE) under prolonged testing times (5 h) in acid (comparable with accelerated stress testing protocols). This result also highlights the use of BDD as a corrosion free electrocatalyst TEM support for fundamental studies, and in practical energy conversion applications. High magnification TEM imaging demonstrates resolution of isolated, single atoms on the BDD-TEM electrode during electrodeposition, due to the low background electron scattering of the BDD surface. Given the high thermal conductivity and stability of the BDD-TEM electrodes, in situ monitoring of thermally induced morphological changes is also possible, shown here for the thermally induced crystallization of amorphous electrodeposited manganese oxide to the electrochemically active γ-phase.