Infrared Thermometer: Ground surface temperature on the tower at 6 meters (b1-level)
Infrared Thermometer: Ground surface temperature on the tower at 6 meters
54 ENVIRONMENTAL SCIENCES↗
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ELM-Wet: Inclusion of a wetland landunit with sub-grid representation of eco-hydrological patches and hydrological forcing in E3SM Land Model (ELM)
Wetlands emit the most biogenic methane (CH4) and present the greatest uncertainty in the global CH4 budget. Modeling these emissions is challenging due to the temporal and spatial variability in wetland structure and CH4 flux rates, along with complex interactions among hydrological, ecological, meteorological, and microbial processes that govern CH4 dynamics. To address these issues, we aim to enhance the accuracy of wetland representation in the U.S. Department of Energy’s Exascale Earth System Model (E3SM) Land Model, ELM. This effort led to the development of ELM-Wet, which incorporates a dedicated wetland landunit with subgrid representation of eco-hydrological patch types. We implement wetland-specific hydrology by imposing site-specific constraints on surface water levels, thereby allowing different patches to sustain varying depths of inundation. Additionally, we refined the calculation of aerenchyma transport diffusivity based on observed conductance across different vegetation types. We validated these enhancements through site-specific simulations of a coastal freshwater wetland, the Salvador WMA Freshwater Marsh (Ameriflux, site ID US-LA2), located in the coast of Louisiana (29.85N,90.29W) at an elevation of 0 m. The site was simulated with ELM-Wet and the default version ELMv1. We use Bayesian Optimization to parameterize CO2 and CH4 fluxes. Eddy covariance observations of CO2 and CH4 fluxes from 2012-2013 were used to train the model and data from 2021 were used for validation. In this repository, we include all the output of all the simulations performed using different versions of ELMv1 and ELM-Wet, all input required to the model, and the Matlab scripts we used to processed the output data. ELM-Wet_flmd.csv includes a detailed description of the datasets files.
54 ENVIRONMENTAL SCIENCES↗
The surface termination of a Fe (III) spin crossover molecular salt
From a comparison of the known molecular stoichiometry and x-ray photoemission spectroscopy, it is evident that the Fe(III) spin crossover salt [Fe(qsal) 2 Ni(dmit) 2 ] has a preferential surface termination with the Ni(dmit) 2 moiety, where qsal = N(8quinolyl)salicylaldimine, and dmit 2- = 1,3-dithiol-2-thione-4,5-dithiolato. This preferential surface termination leads to a significant surface to bulk core level shift for the Ni 2p x-ray photoemission core level, not seen in the corresponding Fe 2p core level spectra. A similar surface to bulk core level shift is seen in Pd 3d in the related [Fe(qsal) 2 ] 2 Pd(dmit) 2 . Inverse photoemission spectroscopy, compared with the x-ray absorption spectra at the Ni-L3,2 edge provides some indication of the density of states resulting from the dmit 2- = 1,3-dithiol-2-thione-4,5-dithiolato ligand unoccupied molecular orbitals and thus supports the evidence regarding surface termination in the Ni(dmit) 2 moiety.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
Data for publication: "A fresh take: Seasonal changes in terrestrial freshwater inputs impact salt marsh hydrology and vegetation dynamics"
This data repository contains data associated with the manuscript "A fresh take: Seasonal changes in terrestrial freshwater inputs impact salt marsh hydrology and vegetation dynamics". This study was conducted at the Elkhorn Slough National Estuarine Research Reserve in Watsonville, California from October 2019 - June 2022. We sought to understand the role of shallow freshwater inputs from adjacent uplands on salt marsh hydrologic behavior and vegetation productivity. This dataset contains CSV files of the following: daily salt marsh subsurface water level and pore water conductivity, monthly vegetation survey measurements, soil core data. Estuary surface water level, conductivity, and local precipitation were downloaded from the National Estuarine Research Reserve System (Centralized Data Management Office) at https://cdmo.baruch.sc.edu/.
54 ENVIRONMENTAL SCIENCES↗
On the hydrogenation of Poly-Si passivating contacts by Al 2 O 3 and SiN x thin films
Doped polycrystalline silicon (poly-Si), when coupled with a thin SiO 2 interlayer, is of large interest for crystalline silicon ( c -Si) solar cells due to its outstanding passivating contact properties. To reach high levels of surface passivation, it is pivotal to hydrogenate the poly-Si and the underlying c -Si/SiO 2 interface. This can be done by capping the poly-Si with a hydrogen-containing dielectric layer such as Al 2 O 3 or SiN x , followed by a thermal anneal. On the basis of recent research, this work addresses several aspects of such hydrogenation by dielectric materials, including the effect of the annealing ambient, the thermal stability and reversibility of hydrogenation, the poly-Si doping level and c -Si surface texture. Additionally, the implementation of hydrogenation of poly-Si by dielectric materials in solar cells is discussed.
14 SOLAR ENERGY↗
Pool boiling critical heat flux studies of accident tolerant fuel cladding materials
Pool boiling experiments have been performed at atmospheric pressure on potential accident tolerant fuel (ATF) cladding materials (Zirlo®, Cr coated Zirlo®, FeCrAl coated Zirlo®, and monolithic SiC) to evaluate the Critical Heat Flux (CHF) points. Corrosion resistant coatings of Cr and FeCrAl alloy were deposited on flat Zirlo® samples using cold spray technology. The as-prepared samples after uniform surface polishing were subjected to autoclave tests at 360 °C water and 18.6 MPa for 360 h to simulate prototypic corrosion of the ATF cladding materials in LWR normal operation. Surface characteristics potentially influencing CHF such as surface morphology, roughness, static contact angle, and surface chemistry were characterized using a suite of characterization methods including scanning electron microscopy, 3D optical profilometry, optical contact angle measurements, and x-ray photoelectron spectroscopy (XPS). Thermo-physical properties of the samples such as density, thermal conductivity, and heat capacity were measured by differential scanning calorimetry and laser flash thermal diffusivity measurement. FeCrAl coatings showed CHF values comparable to bare Zirlo® samples, while slightly lower CHF values were observed for Cr coated samples and bulk SiC flats (produced by chemical vapor deposition, CVD). As-deposited Cr coatings showed 67% higher CHF than the as-polished Cr coatings due to its higher surface roughness level. The autoclave testing for the prepared samples generally increased the CHF except for the surface polished Cr coatings. Similar CHF values of bare Zirlo®, FeCrAl coating, and CVD SiC samples were observed after autoclave test but there were negligible change CHF of Cr coatings. XPS studies indicated that the formation or deposition of a few monolayers of hydrophobic carbonaceous species on surface can affect CHF values. The trends in CHF data are discussed in terms of evolution of the surface characteristics of the ATF materials.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Site-Selective Atomic Layer Deposition on Rutile TiO 2 : Selective Hydration as a Route to Target Point Defects
Routes to area-and especially site-selective atomic layer deposition (ALD) remain an enticing challenge in precision surface science, despite the potentially game-changing capability for many energy applications. An unparalleled level of surface reaction control is required to direct ALD to select sites on the same nominal material, for example, targeted growth on distinct phases, facets, step-edges, and/or defects. However, as a sequential surface synthesis method, ALD is uniquely suited to these challenges, including the possibility of selective deposition at defective surface atom arrangements. Here, we computationally identify conditions for site-selective ALD through hydration of surface defects, including oxygen vacancies and titanium interstitials on low-index rutile TiO 2 facets. First-principles computation is used to predict, as a function of temperature, the hydroxylation of defects that are targeted by proton-exchange-mediated ALD processes. In situ ellipsometric measurements of ALD Al 2 O 3 nucleation on TiO 2 (110) single crystals prepared with and without abundant oxygen vacancies demonstrate striking contrast, corroborating computational predictions and revealing a mechanistically clear path to site-selective ALD.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Reaching for the Edge I: probing the outskirts of massive galaxies with HSC, DECaLS, SDSS, and Dragonfly
ABSTRACT The outer light (stellar haloes) of massive galaxies has recently emerged as a possible low scatter tracer of dark matter halo mass. To test the robustness of outer light measurements across different data sets, we compare the 1D azimuthally averaged surface brightness profiles of massive galaxies using four independent data sets: the Hyper Suprime-Cam survey (HSC), the Dark Energy Camera Legacy Survey (DECaLS), the Sloan Digital Sky Survey (SDSS), and the Dragonfly Wide Field Survey (Dragonfly). We test the sky subtraction and proposed corrections for HSC and DECaLS. For galaxies at z < 0.05, Dragonfly has the best control of systematics, reaching surface brightness levels of μr ≈ 30 mag arcsec−2. At 0.19 < z < 0.50, HSC can reliably recover individual surface brightness profiles to μr ≈ 28.5 mag arcsec−2 (R = 100–150 kpc in semimajor axis). In a statistical sense, DECaLS agrees with HSC to R > 200 kpc. DECaLS and HSC measurements of the stellar mass contained within 100 kpc agree within 0.05 dex. Finally, we use weak lensing to show that measurements of outer light with DECaLS at 0.19 < z < 0.50 show a similar promise as HSC as a low scatter proxy of halo mass. The tests and results from this paper represent an important step forward for accurate measurements of the outer light of massive galaxies and demonstrate that outer light measurements from DECam imaging will be a promising method for finding galaxy clusters.
79 ASTRONOMY AND ASTROPHYSICS↗
Simulative Prediction of Solar Illuminance and Application of the Du-Sharples Model in Estimating Adapted Daylighting Metrics for an Urban Environment
The practice of daylighting in indoor spaces can significantly reduce electricity consumption and carbon emissions, improve human productivity, and enhance mood and cognitive perception. This work discussed the recent developments in daylighting science and practice, computed the periodic variations in average diurnal daylight levels for each month, quantified in terms of global horizontal illuminance and diffuse horizontal illuminance, for Kolkata, India, a city with tropical wet and dry climate, with two empirical luminous efficacy models of estimating solar illuminance, and assessed daylighting metrics with the Du-Sharples model. A program was formulated that could compute and generate daylight data with monthly-hourly solar irradiation data and the Du-Sharples model was utilized to predict dirt-corrected daylighting metrics for three glazing transmittance values and five elemental carbon deposition levels on glazing material. The highest monthly average global horizontal illuminance is recorded in April (64.05 klx for Littlefair model and 66.82 klx for Muneer-Kinghorn model) and the highest monthly average diffuse horizontal illuminance is recorded in July (33.23 klx for Littlefair model and 30.63 klx for Muneer-Kinghorn model). Further, the computed yearly average global and diffuse horizontal illuminance levels agree well with a previous study that applied the Perez model. Yearly average horizontal work surface illuminance level remained >1.5 klx for window-towall area ratio >30 %. The approach adopted in this work and the temporal variation charts of computed exterior daylight level data may assist building service engineers, architects, and indoor lighting practitioners in making informed policy decisions at different stages of building planning.
Engineering↗
Back and forward trajectories on isobaric surfaces for marine ARM sites (c1-level)
Back and forward trajectories on isobaric surfaces for marine ARM sites
ARM↗
The stability of Cl-, Br-, and I-passivated Si(100)-(2 × 1) in ambient environments for atomically-precise pattern preservation
Abstract Atomic precision advanced manufacturing (APAM) leverages the highly reactive nature of Si dangling bonds relative to H- or Cl-passivated Si to selectively adsorb precursor molecules into lithographically defined areas with sub-nanometer resolution. Due to the high reactivity of dangling bonds, this process is confined to ultra-high vacuum (UHV) environments, which currently limits its commercialization and broad-based appeal. In this work, we explore the use of halogen adatoms to preserve APAM-derived lithographic patterns outside of UHV to enable facile transfer into real-world commercial processes. Specifically, we examine the stability of H-, Cl-, Br-, and I-passivated Si(100) in inert N 2 and ambient environments. Characterization with scanning tunneling microscopy and x-ray photoelectron spectroscopy (XPS) confirmed that each of the fully passivated surfaces were resistant to oxidation in 1 atm of N 2 for up to 44 h. Varying levels of surface degradation and contamination were observed upon exposure to the laboratory ambient environment. Characterization by ex situ XPS after ambient exposures ranging from 15 min to 8 h indicated the Br– and I–passivated Si surfaces were highly resistant to degradation, while Cl–passivated Si showed signs of oxidation within minutes of ambient exposure. As a proof-of-principle demonstration of pattern preservation, a H–passivated Si sample patterned and passivated with independent Cl, Br, I, and bare Si regions was shown to maintain its integrity in all but the bare Si region post-exposure to an N 2 environment. The successful demonstration of the preservation of APAM patterns outside of UHV environments opens new possibilities for transporting atomically-precise devices outside of UHV for integrating with non-UHV processes, such as other chemistries and commercial semiconductor device processes.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
Journal Pre-proof3D printed polylactic acid and acrylonitrile butadiene styrene fluidicstructures for biological applications: tailoring bio-material interfaceviasurface modification
Three-dimensional (3D) printing is a rapidly growing technology that best fits for cell culture and other biological applications due to its potential to build immensely complex structures from customized designs. However, use of 3D printed structures for cell adhesion, proliferation, and activation requires tailoring of surface characteristics. In this context, this work investigates the use of two biocompatible 3D printable polymer materials, Poly-L-lactic Acid (PLA) and Acrylonitrile Butadiene Styrene (ABS) for bio applications, and the effect of their post-printing surface modification processes to achieve desired bio functionality. Three post-printing surface modification techniques, alkaline hydrolysis, ultraviolet ozone plasma irradiation and gold thin film deposition are performed with the objective of introducing useful levels of surface functionalities. Poly-L-lysine (PLL) labelled with FITC chromophore is immobilized on the surface modified samples following standard protocols. The effect of surface roughness and porosity of the 3D printed structures on the polypeptide immobilization is compared on as-printed versus mechanically polished surfaces. Different characterization methods, viz., Fluorescence microscopy, Raman Spectroscopy and UV–vis spectroscopy, are used to study the efficacy of the surface modification and PLL immobilization techniques. Our results demonstrated denser PLL attachment on polished hydrolyzed PLA and ABS surfaces which enables the use of these printable polymers for a range of applications such as tissue scaffolds and microfluidics.
3D Printing, PLA, ABS, Biodegradable Polymer, Surf↗
Effect of surface functional groups on MXene conductivity
In this work, we report the in-plane electron transport in the MXenes (i.e., within the MXene layers) as a function of composition using the density-functional tight-binding method, in conjunction with the non-equilibrium Green’s functions technique. Our study reveals that all MXene compositions have a linear relationship between current and voltage at lower potentials, indicating their metallic character. However, the magnitude of the current at a given voltage (conductivity) has different trends among different compositions. For example, MXenes without any surface terminations (Ti 3 C 2 ) exhibit higher conductivity compared to MXenes with surface functionalization. Among the MXenes with –O and –OH termination, those with –O surface termination have lower conductivity than the ones with –OH surface terminations. Interestingly, conductivity changes with the ratio of –O and –OH on the MXene surface. Our calculated I–V curves and their conductivities correlate well with transmission functions and the electronic density of states around the Fermi level. The surface composition-dependent conductivity of the MXenes provides a path to tune the in-plane conductivity for enhanced pseudocapacitive performance.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Surface Finishing and Coating Parameters Impact on Additively Manufactured Binder-Jetted Steel–Bronze Composites
In this paper, electroless nickel plating is explored for the protection of binder-jetting-based additively manufactured (AM) composite materials. Electroless nickel plating was attempted on binder-jetted composites composed of stainless steel and bronze, resulting in differences in the physicochemical properties. We investigated the impact of surface finishing, plating solution chemistry, and plating parameters to attain a wide range of surface morphologies and roughness levels. We employed the Keyence microscope to quantitatively evaluate dramatically different surface properties before and after the coating of AM composites. Scanning electron microscopy revealed a wide range of microstructural properties in relation to each combination of surface finishing and coating parameters. We studied chempolishing, plasma cleaning, and organic cleaning as the surface preparation methods prior to coating. We found that surface preparation dictated the surface roughness. Taguchi statistical analysis was performed to investigate the relative strength of experimental factors and interconnectedness among process parameters to attain optimum coating qualities. The quantitative impacts of phosphorous level, temperature, surface preparation, and time factor on the roughness of the nickel-plated surface were 17.95%, 8.2%, 50.02%, and 13.21%, respectively. On the other hand, the quantitative impacts of phosphorous level, temperature, surface preparation, and time factor on the thickness of nickel plating were 35.12%, 41.40%, 3.87%, and 18.24%, respectively. The optimum combination of the factors’ level projected the lowest roughness of Ra at 7.76 µm. The optimum combination of the factors’ level projected the maximum achievable thickness of ~149 µm. This paper provides insights into coating process for overcoming the sensitivity of AM composites in hazardous application spaces via robust coating.
36 MATERIALS SCIENCE↗
Pinning of energy transitions of defects, complexes, and surface states in AlGaN alloys
In this work, we determine the dependence of the defect transition energies, electronic bands, and surface charge neutrality levels in AlGaN. With Vacuum level as reference, we show that energy transitions of localized defects and the surface Fermi level are independent of the alloy composition as electronic bands diverge with the increase in the bandgap as a function of alloy composition. The invariance of localized states on the alloy composition creates a convenient internal reference energy with respect to which other energy states may be measured. We demonstrate a higher generality to the universality rule with the independence of deep transition states of otherwise shallow donor type defects [(+1/+3) transition for VN] and defect complexes (C N +Si III ) in addition to the earlier predicted independent nature of mid-gap states when they are either the antibonding state between cationic impurities and host anion or acceptors at anion sites.
36 MATERIALS SCIENCE↗
Surface and bulk two-level-system losses in lithium niobate acoustic resonators
Lithium niobate (LN) is a promising material for building acoustic resonators used in quantum applications, but its performance is limited by poorly understood material defects called two-level systems (TLSs). Here, in this work, we fabricate high-performance acoustic resonators from LN with quality factors up to 6 ×10 7 and use them to separate bulk and surface contributions to TLS loss. By comparing these bulk acoustic wave (BAW) resonators with previous surface-acoustic-wave and phononic-crystal studies, we show that devices with high surface-participation ratios are limited by surface TLSs, while our BAW devices reveal an intrinsic bulk TLS limit. Through systematic surface treatments and microscopy, we demonstrate that BAW resonator performance remains unchanged despite surface modifications, confirming operation in a bulk-limited regime. Here, our work establishes quantitative bounds on both surface and bulk TLS losses in LN within the context of the material growth and fabrication approaches we have pursued, and it provides guidance for future device engineering and materials development.
acoustic wave phenomena↗
A numerical study of process complexity in permafrost dominated regions
Numerical modeling of permafrost dynamics requires adequate representation of atmospheric and surface processes, a reasonable parameter estimation strategy, and site-specific model development. The three main research objectives of the study are: (i) to propose a novel methodology that determines the required level of surface process complexity of permafrost models by conducting parameter sensitivity and calibration, (ii) to design and compare three numerical models of increasing surface process complexity, and (iii) to calibrate and validate the numerical models at the Yakou catchment on the Qinghai-Tibet Plateau as an exemplary study site. The calibration was carried out by coupling the Advanced Terrestrial Simulator (numerical model) and PEST (calibration tool). Simulation results showed that (i) A simple numerical model that considers only subsurface processes can simulate active layer development with the same accuracy as other more complex models that include surface processes. (ii) Peat and mineral soil layer permeability, Van Genuchten alpha, and porosity are highly sensitive. (iii) Liquid precipitation aids in increasing the rate of permafrost degradation. (iv) Deposition of snow insulated the subsurface during the thaw initiation period. We have developed and released an integrated code that couples the numerical software ATS to the calibration software PEST. The numerical model can be further used to determine the impacts of climate change on permafrost degradation.
Calibration↗
Atomistic insights into the heat conductance across the interfaces between erythritol and different metals: A non-equilibrium molecular dynamics study
The heat conductance across the interface between a phase change material (PCM) and the metal shell is important for thermal design of latent heat storage systems. Non-equilibrium molecular dynamics simulations were carried out in this work to unravel, at the atomistic level, the interfacial heat conductance mechanisms between erythritol (the most promising medium-temperature polyol PCM) and two different metals (i.e., copper and aluminum). The interfacial contact ratio was introduced as a parameter to represent different contact conditions at the interfaces, for example, different surface roughness levels of the metals. It was found that with the increase of interfacial contact ratio, the temperature difference between the erythritol/metal interfaces decreases, whereas the interfacial heat transfer coefficient increases gradually. At the perfect contact condition, i.e., the interfacial contact ratio reaches 100%, the interfacial heat transfer coefficients across the erythritol/Cu and erythritol/Al interfaces were predicted to be 398 ± 26 MW/m 2 K and 544 ± 11 MW/m 2 K, respectively. The interfacial heat conductance of erythritol/Al is better than that of erythritol/Cu. The mismatch of atomic spectral density across the interfaces between erythritol and the two metals was analyzed and distinguished. These results could guide the selection of packaging materials and the thermal design of erythritol-based latent heat storage systems.
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗