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1. Obsidian hydration dating by infrared transmission spectroscopy

   https://doi.org/10.1111/arcm.12982  

   Franchetti, Fernando; Neme, Gustavo; Gil, Adolfo; Salgan, M_Laura; Rogers, Alexander_K; Davenport, James; Garvey, Raven; Trofimova, Olga; Ladefoged, Thegn_N; Stevenson, Christopher_M (May 2024, Archaeometry)

   Abstract The obsidian dating method converts the quantity of diffused molecular water within a near‐surface hydration layer to elapsed time using an experimentally derived diffusion coefficient predicted from the structural water content of the glass. Infrared spectroscopic transmission measurements on transparent archaeological samples record vibrational responses of water bands in the near‐infrared region, permitting determination of structural water content (OH), and the amount of diffused ambient water (H₂O). In this application, the H₂O water band at 5200 cm⁻¹is measured directly. The accuracy of the approach is assessed by an evaluation of the precision of each contributing variable. The new protocol is evaluated using obsidian artifacts from radiocarbon‐dated deposits at Salamanca Cave in Argentina. 

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2. Photothermal Utility Heating with Diffused Indoor Light via Multiple Transparent Fe 3O4 @Cu2-xS Thin Films

   https://doi.org/10.1002/ente.202400703  

   Katepalli, Anudeep; Tene, Neshwanth Kumar; Wang, Yuxin; Harfmann, Anton; Bonmarin, Mathias; Krupczak, John; Shi, Donglu (August 2024, Energy Technology)

   The research presented in this study aims to tackle a pivotal challenge in solar energy technologies: how to sustain energy production when direct sunlight is not readily available. By introducing a novel photothermal radiator that effectively harnesses diffused light through plasmonic Fe₃O₄@Cu2-xS nanoparticles, we seek to offer a sustainable solution for maintaining comfortable indoor temperatures without heavy reliance on traditional solar sources. Our approach involves the use of UV and IR lights to photothermally activate transparent Fe₃O₄@Cu2-xS thin films, showcasing a proactive strategy to optimize energy capture even in low-light scenarios such as cloudy days or nighttime hours. This innovative technology carries immense potential for energy-neutral buildings, paving the way to reduce dependence on external energy grids and promoting a more sustainable future for indoor heating and comfort control. The developed photothermal radiator incorporates multiple transparent thin films infused with plasmonic Fe₃O₄@Cu2-xS nanoparticles, known for their robust UV and IR absorptions driven by Localized Surface Plasmon Resonance (LSPR). Through the application of UV and IR lights, these thin films efficiently convert incident photons into thermal energy. Our experiments within a specially constructed Diffused Light Photothermal Box (DLPB), designed to simulate indoor environments, demonstrate the system's capability to raise temperatures above 50°C effectively. This pioneering photothermal radiator offers a promising pathway for sustainable heat generation in indoor spaces, harnessing ubiquitous diffused light sources to enhance energy efficiency. 

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3. Online Topology Inference from Streaming Stationary Graph Signals

   https://doi.org/10.1109/DSW.2019.8755560  

   Shafipour, Rasoul; Hashemi, Abolfazl; Mateos, Gonzalo; Vikalo, Haris (June 2019, 2019 IEEE Data Science Workshop (DSW))

   We address the problem of online topology inference from streaming nodal observations of graph signals generated by linear diffusion dynamics on the sought graph. To that end, we leverage the stationarity of the signals and use the so-called graph-shift operator (GSO) as a matrix representation of the graph. Under this model, estimated covariance eigenvectors obtained from streaming independent graph signals diffused on the sought network are a valid estimator of the GSO's spectral templates. We develop an ADMM algorithm to find a sparse and structurally admissible GSO given the eigenvectors estimate. Then, we propose an online scheme that upon sensing new diffused observations, efficiently updates eigenvectors (thus makes more accurate on expectation) and performs only one or a few iterations of the mentioned ADMM until the new data is observed. Numerical tests illustrate the effectiveness of the proposed topology inference approach in recovering large scale graphs, adapting to streaming information, and accommodating changes in the sought network. 

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4. Analysis of thermal grooving effects on vortex penetration in vapor-diffused Nb ₃ Sn

   https://doi.org/10.1088/1361-6668/ad9416  

   Lechner, Eric M; Trofimova, Olga; Angle, Jonathan W; DiGuilio, Madison C; Pudasaini, Uttar (November 2024, Superconductor Science and Technology)

   Abstract While Nb₃Sn theoretically offers better superconducting radio-frequency (RF) cavity performance (Q₀and $E_{\mathrm{acc}}$) to Nb at any given temperature, peak RF magnetic fields consistently fall short of the ∼400 mT prediction. The relatively rough topography of vapor-diffused Nb₃Sn is widely conjectured to be one of the factors that limit the attainable performance of Nb₃Sn-coated Nb cavities prepared via Sn vapor diffusion. Here we investigate the effect of coating duration on the topography of vapor-diffused Nb₃Sn on Nb and calculate the associated magnetic field enhancement and superheating field suppression factors using atomic force microscopy topographies. It is shown that the thermally grooved grain boundaries are major defects which may contribute to a substantial decrease in the achievable accelerating field. The severity of these grooves increases with total coating duration due to the deepening of thermal grooves during the coating process. 

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5. Smooth, homogeneous, high-purity Nb ₃ Sn superconducting RF resonant cavity by seed-free electrochemical synthesis

   https://doi.org/10.1088/1361-6668/acf5ab  

   Sun, Zeming; Baraissov, Zhaslan; Porter, Ryan D.; Shpani, Liana; Shao, Yu-Tsun; Oseroff, Thomas; Thompson, Michael O.; Muller, David A.; Liepe, Matthias U. (September 2023, Superconductor Science and Technology)

   Abstract Workbench-size particle accelerators, enabled by Nb₃Sn-based superconducting radio-frequency (SRF) cavities, hold the potential of driving scientific discovery by offering a widely accessible and affordable source of high-energy electrons and x-rays. Thin-film Nb₃Sn RF superconductors with high quality factors, high operation temperatures, and high-field potentials are critical for these devices. However, surface roughness, non-stoichiometry, and impurities in Nb₃Sn deposited by conventional Sn-vapor diffusion prevent them from reaching their theoretical capabilities. Here we demonstrate a seed-free electrochemical synthesis that pushes the limit of chemical and physical properties in Nb₃Sn. Utilization of electrochemical Sn pre-deposits reduces the roughness of converted Nb₃Sn by five times compared to typical vapor-diffused Nb₃Sn. Quantitative mappings using chemical and atomic probes confirm improved stoichiometry and minimized impurity concentrations in electrochemically synthesized Nb₃Sn. We have successfully applied this Nb₃Sn to the large-scale 1.3 GHz SRF cavity and demonstrated ultra-low BCS surface resistances at multiple operation temperatures, notably lower than vapor-diffused cavities. Our smooth, homogeneous, high-purity Nb₃Sn provides the route toward high efficiency and high fields for SRF applications under helium-free cryogenic operations. 

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