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1. In situ and ex situ processes for synthesizing metal multilayers with electronically conductive interfaces

   https://doi.org/10.1063/5.0084573  

   Angeles, Frank ; Shi, Xinping ; Wilson, Richard B. ( June 2022 , Journal of Applied Physics)

   A number of technological applications and scientific experiments require processes for preparing metal multilayers with electronically and thermally conductive interfaces. We investigate how in situ vs ex situ synthesis processes affect the thermal conductance of metal/metal interfaces. We use time-domain thermoreflectance experiments to study thermal transport in Au/Fe, Al/Cu, and Cu/Pt bilayer samples. We quantify the effect of exposing the bottom metal layer to an ambient environment prior to deposition of the top metal layer. We observe that for Au/Fe, exposure of the Fe layer to air before depositing the top Au layer significantly impedes interfacial electronic currents. Exposing Cu to air prior to depositing an Al layer effectively eliminates interfacial electronic heat currents between the two metal layers. Exposure to air appears to have no effect on interfacial transport in the Cu/Pt system. Finally, we show that a short RF sputter etch of the bottom layer surface is sufficient to ensure a thermally and electronically conductive metal/metal interface in all materials we study. We analyze our results with a two-temperature model and bound the electronic interface conductance for the nine samples we study. Our findings have applications for thin-film synthesis and advance fundamental understanding of electronic thermal conductance at different types of interfaces between metals. 

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2. Role of in situ (in contact with biomass) and ex situ (in contact with pyrolysis vapors) transition metal catalysts on pyrolysis of cherry pits

   https://doi.org/10.1016/j.fuel.2023.129062  

   Hubble, Andrew H. ; Childs, Bridget A. ; Pecchi, Matteo ; Sudibyo, Hanifrahmawan ; Tester, Jefferson W. ; Goldfarb, Jillian L. ( November 2023 , Fuel)
3. Ex Situ and In Situ Thermal Transformations of M-50 Pitch Revealed by Non-contact Atomic Force Microscopy

   https://doi.org/10.1021/acs.energyfuels.1c02487  

   Chen, Pengcheng ; Metz, Jordan N. ; Gross, Adam S. ; Smith, Stuart E. ; Rucker, Steven P. ; Yao, Nan ; Zhang, Yunlong ( November 2021 , Energy & Fuels)
4. Comparing in-situ and ex-situ stress measurements in polymineralic rocks

   Goddard, Rellie ; Hansen, Lars N. ; Wallis, David ; Stipp, Michael ; Holyoke, Caleb W. ; Kohlstedt, David L. ; Goldsby, David L. ; Durham, William B. ; Kumamoto, Kathryn M. ; Thom, Christopher ( December 2018 , American Geophysical Union Fall Meeting)

   Constraints on the state of stress in the lithosphere are fundamental to understanding a breadth of geological phenomena. Paleo-stresses are generally estimated using microstructural elements for which there are experimentally calibrated relationships with applied stress, with an emphasis on recrystallised grain-size piezometers. However, it is often difficult to clearly distinguish newly recrystallised grains from the relict matrix. Furthermore, these grain-size piezometers are only applicable to rocks consisting of a single mineral. An alternative proxy for paleo-stress in polymineralic rocks is the average subgrain size. Unfortunately, estimates of subgrain size differ significantly among different measurement methods, and therefore, piezometers must be individually calibrated for the method used. Existing subgrain-size piezometers are based on calibrations using optical or transmission electron microscopy. We use electron backscatter diffraction (EBSD), a common method of subgrain-boundary characterisation, to calibrate subgrain-size piezometers for both olivine and quartz. To test the application of our olivine subgrain-size piezometer to polymineralic rocks, we deformed synthetic mixtures of olivine and orthopyroxene. Experiments were conducted using a Deformation-DIA apparatus at beamline 6BM-B Advanced Photon Source, Argonne National Laboratory. These experiments offer the unique possibility of simultaneously deforming the sample and measuring the average stresses within each phase using X-ray diffraction, before applying subgrain-size piezometry to the recovered samples. The results provide tests of (1) the manner in which stress is partitioned between phases, (2) whether the stresses measured in each phase by X-ray diffraction are comparable to those estimated by subgrain-size piezometry, and (3) whether stresses from subgrain piezometry can be used to estimate the macroscopic average applied stress. Stresses estimated from X-ray diffraction agree well with those made from subgrain-size piezometry in both monomineralic and polymineralic samples. In harzburgites, average stresses are similar in both phases and indicate that in this system, subgrain-size piezometric measurements from a single phase can be used to estimate the bulk stress. 

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5. Ex Situ and In Situ Analyses of the Mechanism of Electrocatalytic Hydrogen Peroxide Production by Co x Zn 1–x O (0 x < 0.018) Materials in Alkaline Media

   https://doi.org/10.1021/acsaem.1c04030  

   Del Pilar Albadalejo, Joselyn ; Alonso-Sevilla, Suheily ; Cintrón, Nicohl I. ; Feng, Xinran ; García, Ángel D. ; Martínez-Torres, Dinorah D. ; Rodríguez, Astrid M. ; Román-Montalvo, Natalia I. ; Torres, José I. ; Yang, Yao ; et al ( June 2022 , ACS Applied Energy Materials)

   Metal oxide semiconductors have attracted much attention due to their versatility in different applications, ranging from biosensing to green energy-harvesting technologies. Among these metal oxides, oxide-based diluted magnetic semiconductors have also been proposed for fuel cell applications, especially for the oxygen reduction reaction (ORR) and the oxygen evolution reaction. However, the catalytic mechanism has been proposed to follow a two-electron pathway, forming hydrogen peroxide, instead of the four-electron pathway. Herein, we report cobalt-doped zinc oxide (CoxZn1–xO, 0 < x < 0.018) materials prepared using a co-precipitation method suitable for the electrocatalytic production of hydrogen peroxide. The electrocatalytic performance of CoxZn1–xO materials showed up to 60% hydrogen peroxide production with onset potentials near 649 mV, followed by the two-electron ORR mechanism. Ex situ X-ray absorption spectroscopy experiments at the Co K-edge demonstrated the presence of Co(II) ions at tetrahedral sites within the ZnO lattice. 

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