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1. Intrinsic Constraints on Asymmetric Turbulent Transport of Scalars Within the Constant Flux Layer of the Lower Atmosphere: CONSTANT FLUX LAYER

   https://doi.org/10.1002/2018GL077021  

   Li, Dan ; Katul, Gabriel G. ; Liu, Heping ( February 2018 , Geophysical Research Letters)

   A widely used assumption in boundary layer meteorology is the z independence of turbulent scalar fluxes Fs throughout the atmospheric surface layer, where z is the distance from the boundary. This assumption is necessary for the usage of Monin-Obukhov Similarity Theory and for the interpretation of eddy covariance measurements of Fs when using them to represent emissions or uptake from the surface. It is demonstrated here that the constant flux assumption offers intrinsic constraints on the third-order turbulent transport of Fs in the unstable atmospheric surface layer. When enforcing z independence of Fs on multilevel Fs measurements collected above different surface cover types, it is shown that increasing instability leads to a novel and universal description of (i) the imbalance between ejecting and sweeping eddy contributions to Fs and (ii) the ratio formed by a dimensionless turbulent transport of Fs and a dimensionless turbulent transport of scalar variance. When combined with structural models for the turbulent transport of Fs, these two findings offer a new perspective on “closing” triple moments beyond conventional gradient diffusion schemes. A practical outcome is a diagnostic of the constant flux assumption from single-level Fs measurements. 

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2. Thermal transport in layer-by-layer assembled polycrystalline graphene films

   https://doi.org/10.1038/s41699-019-0092-8  

   Estrada, David ; Li, Zuanyi ; Choi, Gyung-Min ; Dunham, Simon N. ; Serov, Andrey ; Lee, Jungchul ; Meng, Yifei ; Lian, Feifei ; Wang, Ning C. ; Perez, Alondra ; et al ( March 2019 , npj 2D Materials and Applications)

   New technologies are emerging which allow us to manipulate and assemble 2-dimensional (2D) building blocks, such as graphene, into synthetic van der Waals (vdW) solids. Assembly of such vdW solids has enabled novel electronic devices and could lead to control over anisotropic thermal properties through tuning of inter-layer coupling and phonon scattering. Here we report the systematic control of heat flow in graphene-based vdW solids assembled in a layer-by-layer (LBL) fashion. In-plane thermal measurements (between 100 K and 400 K) reveal substrate and grain boundary scattering limit thermal transport in vdW solids composed of one to four transferred layers of graphene grown by chemical vapor deposition (CVD). Such films have room temperature in-plane thermal conductivity of ~400 Wm⁻¹ K⁻¹. Cross-plane thermal conductance approaches 15 MWm⁻² K⁻¹for graphene-based vdW solids composed of seven layers of graphene films grown by CVD, likely limited by rotational mismatch between layers and trapped particulates remnant from graphene transfer processes. Our results provide fundamental insight into the in-plane and cross-plane heat carrying properties of substrate-supported synthetic vdW solids, with important implications for emerging devices made from artificially stacked 2D materials.

    

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3. Degradation Effects at the Porous Transport Layer/Catalyst Layer Interface in Polymer Electrolyte Membrane Water Electrolyzer

   https://doi.org/10.1149/1945-7111/acc1a5  

   Liu, Chang ; Shviro, Meital ; Bender, Guido ; Gago, Aldo S. ; Morawietz, Tobias ; Dzara, Michael J. ; Biswas, Indro ; Gazdzicki, Pawel ; Kang, Zhenye ; Zaccarine, Sarah F. ; et al ( March 2023 , Journal of The Electrochemical Society)

   The porous transport layer (PTL)/catalyst layer (CL) interface plays a crucial role in the achievement of high performance and efficiency in polymer electrolyte membrane water electrolyzers (PEMWEs). This study investigated the effects of the PTL/CL interface on the degradation of membrane electrode assemblies (MEAs) during a 4000 h test, comparing the MEAs assembled with uncoated and Ir-coated Ti PTLs. Our results show that compared to an uncoated PTL/CL interface, an optimized interface formed when using a platinum group metal (PGM) coating, i.e., an iridium layer at the PTL/CL interface, and reduced the degradation of the MEA. The agglomeration and formation of voids and cracks could be found for both MEAs after the long-term test, but the incorporation of an Ir coating on the PTL did not affect the morphology change or oxidation of IrO_xin the catalyst layer. In addition, our studies suggest that the ionomer loss and restructuring of the anodic MEA can also be reduced by Ir coating of the PTL/CL interface. Optimization of the PTL/CL interface improves the performance and durability of a PEMWE.

    

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4. Anisotropic chloride transport in 3D printed concrete and its dependence on layer height and interface types

   https://doi.org/10.1016/j.addma.2023.103405  

   Surehali, Sahil ; Tripathi, Avinaya ; Nimbalkar, Atharwa Samir ; Neithalath, Narayanan ( January 2023 , Additive Manufacturing)
5. Improved moisture resistance and interfacial recombination of perovskite solar cells by doping oleylamine in spiro-OMeTAD based hole-transport layer

   https://doi.org/10.1063/5.0092110  

   Liu, Shan ; Wu, Shuyue ; Xia, Pufeihong ; Xie, Haipeng ; Yuan, Xiaoming ; Li, Youzhen ; Kong, Deming ; Huang, Han ; Gao, Yongli ; Zhou, Conghua ( June 2022 , Applied Physics Letters)

   Hydrophobic and long-chain molecule oleylamine is used to modify the spiro-OMeTAD matrix, which is then adopted for the hole-transport layer in perovskite solar cells. It is observed that after moderate doping, the power conversion efficiency of the devices increases from 17.82 (±1.47)% to 20.68 (±0.77)%, with the optimized efficiency of 21.57% (AM 1.5G, 100 mW/cm2). The improved efficiency is ascribed to the favored charge extraction and retarded charge recombination, as reflected by transient photovoltage/photocurrent curves and impedance spectroscopy measurement. In addition, the grazing incidence photoluminescence spectrum reveals that oleylamine doping causes a blue shift of the luminescence peak of the surface layer of the halide perovskite film, while the Mott−Schottky study observes 100 mV increment in the built-in potential, both of which indicate possible defect passivation behavior on the perovskite. Moreover, an accelerated damp test observes that moisture resistance of the device is also upgraded, which is due to the improved hydrophobicity of the spiro-OMeTAD matrix. 

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