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Formation of C–N containing compounds from plasma-catalytic coupling of CH4and N2over various transition metals (Ni, Pd, Cu, Ag, and Au) is investigated using a multimodal spectroscopic approach, combining polarization-modulation infrared reflection–absorption spectroscopy (PM-IRAS) and optical emission spectroscopy (OES). Through sequential experiments utilizing CH4and N2nonthermal plasmas, we minimize plasma-phase reactions and identify key intermediates for C–N coupling on metal surfaces. Results show that simultaneous CH4and N2exposure with plasma stimulation produces surface C–N species. However, N2–CH4sequential exposure does not lead to C–N species formation, while CH4–N2sequential exposure reveals the presence of CHxsurface species and CN radical species as key precursors to C–N species formation. From further analysis using X-ray photoelectron spectroscopy and liquid chromatography–mass spectrometry, the influence of exposure conditions on the degree of nitrogen incorporation and the nature of C–N species formed were revealed. The work highlights the importance of surface chemistry and exposure conditions in surface C–N coupling with plasma stimulation.

Herein, we present a membrane-based system designed to capture CO2from dilute mixtures and convert the captured CO2into value-added products in a single integrated process operated continuously under mild conditions. Specifically, we demonstrate that quaternized poly(4-vinylpyridine) (P4VP) membranes are selective CO2separation membranes that are also catalytically active for cyclic carbonate synthesis from the cycloaddition of CO2to epichlorohydrin. We further demonstrate that quaternized P4VP membranes can integrate CO2capture, including from dilute mixtures down to 0.1 kPa of CO2, with CO2conversion to cyclic carbonates at 57 °C and atmospheric pressure. The catalytic membrane acts as both the CO2capture and conversion medium, providing an energy-efficient alternative to sorbent-based capture, compression, transport, and storage. The membrane is also potentially tunable for the conversion of CO2to a variety of products, including chemicals and fuels not limited to cyclic carbonates, which would be a transformative shift in carbon capture and utilization technology.

This work describes a new operando surface enhanced Raman spectroscopy (SERS) platform that we developed for use with polymeric membranes that includes (1) a method for preparing SERS-active polymer membranes and (2) a permeation cell with optical access for SERS characterization of membranes under realistic operating conditions. This technique enables the direct correlation of membrane structure to its performance under realistic operating conditions by combining in situ SERS characterization of the molecular structure of polymer membranes and simultaneous measurement of solute permeation rates on the same sample. Using the new operando SERS technique, this work aims to clarify the unknown mechanisms by which reactive amines facilitate CO2transport across polyvinylamine (PVAm), a prototypical facilitated transport membrane for CO2separations. We show that a small amount of plasmonic silver particles added to the PVAm solution prior to knife-casting selectively enhances the sensitivity to detection of chemical intermediates (e.g., carbamate) formed in the PVAm film due to the surface-enhanced Raman scattering effect with only minimal effect on the CO2permeance and selectivity of the membrane. Operando SERS characterization of PVAm during exposure to humidified CO2/CH4biogas mixtures at room temperature shows that CO2permeates across PVAm primarily as carbamate species. This work clarifies the previously unknown mechanism of CO2facilitated transport across PVAm and establishes a new operando SERS platform that can be used with a wide range of polymer membrane systems. This technique can be used to elucidate fundamental transport mechanisms in polymer membranes, to establish reliable structure-performance relationships, and for real-time diagnostics of membrane fouling, among other applications.

AbstractIntroduction:Military chaplains play a vital role in helping the military accomplish their missions. These chaplains can be exposed to traumatic experiences during their deployments with some of them developing posttraumatic stress disorder (PTSD). Method:Using in-depth interviews with 17 former and active-duty chaplains who have been diagnosed with PTSD, this study employs classical grounded theory to formulate a conceptual model explaining key factors that contribute to their trauma resiliency. Results:The conceptual model derived from grounded theory analysis of the interviews theorizes that chaplains with PTSD who have a greater number of overall and religious/spiritual protective factors and fewer overall and religious/spiritual risk factors are more resilient to military-related trauma experiences. Alternatively, chaplains who have more overall and religious/spiritual risk factors and fewer of these protective factors demonstrate decreased resiliency. Key risk factors included high levels of guilt, perceived weakness and stigma associated with symptoms, heavy work demands during deployments, competitive work environments, isolation, and unhelpful leadership responses. Discussion:Implications for military behavioral health to support military chaplains are highlighted. They include recommendations for increased and targeted psychoeducation efforts, expanded use of camaraderie-based approaches/fostering informal support, incorporation of chaplain’s faith/spirituality, increased use of narrative and cognitive interventions, and advocating for chaplains.

Cu-based catalysts are highly active and selective for several CO2conversion reactions; however, traditional monometallic Cu-based catalysts suffer poor thermal stability due to the aggregation of copper particles at high temperatures. In this work, we demonstrate a crystal engineering strategy to controllably prepare copper/silica (CuOx/SiO2) catalysts for the reverse water gas shift reaction (RWGS) at high temperatures. We show that CuOx/SiO2catalysts derived from the in situreduction of pure copper silicate nanotubes in a CO2and H2atmosphere exhibit superior catalytic activity with enhanced stability compared to traditional monometallic Cu-based catalysts for the RWGS at high temperatures. Detailed structural characterization reveals that there is a strong interaction between Cu and SiO2in CuOx/SiO2catalysts, which produces more Cu+sites and smaller CuOxnanoparticles. Moreover, CuOx/SiO2catalysts possess a unique dot core/rod shell structure, which could prevent the aggregation of Cu particles. This structural confinement effect, enhanced CO2adsorption by Cu+, and small CuOxnanoparticles presumably caused the catalyst’s extraordinary activity with enhanced stability at high temperatures.