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SSRN 2024年

作者： Nogueira, Felipe Hermínio Meireles Ribeiro, Sharon Gomes Lima, Guilherme Santos Moreira, Luís Clênio Jario da Rocha Neto, Odílio Coimbra Nogueira, Ricardo Emílio Ferreira Quevedo dos Santos Teixeira, Adunias Department of Agricultural Engineering Federal University of Ceara Fortaleza60455-760 Brazil Soil Science Graduate Program Federal University of Ceara Fortaleza60455-760 Brazil Department of Agronomy Federal Institute of Education Science and Technology of Ceara Limoeiro do Norte62930-000 Brazil Department of Metallurgical and Materials Engineering Federal University of Ceara Fortaleza60455-760 Brazil

This study proposes the development and evaluation of a new portable multispectral instrument to estimate the leaf nitrogen concentration in maize crops in the field. The MSPAT (Multispectral Soil Plant Analysis Tools) includes the AS7265x sensor, which has 18 bands and covers the spectrum from 410 to 940 nm. The device was designed to be portable, using the ESP32 microcontroller and incorporating such functionality as data storage on a MicroSD card, communication with a smartphone via WiFi and geolocation of the acquired data. The MSPAT was evaluated in an experiment conducted at the Federal University of Ceará (UFC), where the maize was subjected to different doses of nitrogen fertiliser (0, 60, 90, 120, 150 and 180 ***−1 N). Spectral readings were taken at three phenological stages (V5, V10, R2) using the MSPAT, the SPAD-502 chlorophyll meter and the FieldSpec PRO FR3 spectroradiometer. After taking the optical measurements, the nitrogen content of the leaves was determined in the laboratory using the method proposed by Kjeldahl. The data analysis included the calculation of normalised ratio indices (NRIs) for the estimation using linear regression, and the application of multivariate statistical methods (PLSR and PCR) for predicting the leaf nitrogen concentration (LNC). The results showed that the MSPAT index with the best performance used the 900 nm band in a normalised ratio with the 560 nm band (R2 = 0.64) at stage V10. In the validation, the MSPAT presented an R2 of 0.79, demonstrating superior performance to the SPAD-502, which achieved an R2 of 0.70. This confirms the potential of the MSPAT compared to commercial equipment, and made it possible to obtain similar results to the reference spectroradiometer. The PLSR model with data from the FieldSpec 3 provided important validation metrics when using reflectance data with first-derivative transformation (R2 = 0.88, RMSE = 1.94 and MAE = 1.28). When using the MSPAT, PLSR (R2 = 0.75, RMSE = 2.77 and MAE = 2

关键词： Network security

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Exploring the Potential of Tesla Valve for Filtering and Sorting Microscale Active Swimmers: A Computational Study

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SSRN 2023年

作者： Rogers, Ariel He, Zhiyao Wang, Yong Department of Physics University of Arkansas FayettevilleAR72701 United States Department of Computer Science and Computer Engineering University of Arkansas FayettevilleAR72701 United States Materials Science & Engineering Program University of Arkansas FayettevilleAR72701 United States Cell & Molecular Biology Program University of Arkansas FayettevilleAR72701 United States

An interesting connection between shark spiral intestines and the Tesla valve was proposed recently;however, how Tesla valves interact with active matters and the potential applications of Tesla valves in biology remain largely unexplored. Here, we present a computational study on the potential use of Tesla valves for filtering and sorting microscale active swimmers such as bacteria. We investigated the behavior of microswimmers passing through the Tesla valve at different linear and angular velocities using numerical simulations, and quantified the diodicity of the Tesla valve for active swimmers. Our results demonstrate that the Tesla valve can effectively filter and sort microscale swimmers based on their swimming behavior. The findings of this study suggest that Tesla valves could have potential applications in microscale sorting and chromatography, with significant implications for biomedical and environmental engineering. © 2023, The Authors. All rights reserved.

关键词： Bacteria

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Electronic Structures and Thermoelectric Properties of Heavily Doped N-Type Zrcobi from First Principles Calculations

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SSRN 2022年

作者： Ibrahim, Nura Ahmed, Ridwan A. Adri, Huda Reisya, Ichwani Department of Physics Ahmadu Bello University Zaria Nigeria Materials Science and Engineering Program Department of Mechanical Engineering Worcester Polytechnic Institute WorcesterMA01609 United States

We present a theoretical investigation on the electronic structures and the thermoelectric properties of doped ZrCoBi half-Heusler compound using a combination of density functional theory calculations, semi classical Boltzmann transport theory and deformation potential theory. The effect of doping is described by a combination of rigid band approximation (RBA) and a model that explicitly includes the dopant atom within the lattice of ZrCoBi. The results demonstrate a high power factor with considerable n- and p-doping concentrations at high temperatures. Our findings further reveal that the electronic transport coefficients of ZrCo0.75M0.25Bi (M = Ni, Pd, Pt) are comparable because of their identical electronic structures. At 900 K, a high figure of merit (ZT) of ~ 0.35, ~ 0.38, and ~ 0.40 are obtained for ZrCo0.75Ni0.25Bi, ZrCo0.75Pd0.25Bi and ZrCo0.75Pt0.25Bi respectively. © 2022, The Authors. All rights reserved.

关键词： Electronic structure

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Impact damage and injection repair strength restoration 36

Impact damage and injection repair strength restoration

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36th Technical Conference of the American Society for Composites 2021: Composites Ingenuity Taking on Challenges in Environment-Energy-Economy, ASC 2021

作者： Massey, Justin Romasko, Barrett Kim, Hyonny Materials Science and Engineering Program University of California San Diego La Jolla CA92093 United States Department of Structural Engineering University of California San Diego La Jolla CA92093 United States

ISBN: (纸本)9781713837596

Impact damage to composite structures can lead to a range of damage modes. Of interest is modest damage composed of delaminations less than 50 mm in size, and no visible impact-side fiber breakage. While resin injection is a current-practice repair technique that can be used to address these damage modes in a manner that is much less invasive than bonded scarf patch repair, the injection technique is not currently credited as one restoring strength back to laminate. Issues of quantifying the removal of any internal contamination, assessing degree of resin fill, and demonstration of how much strength is restored are being addressed within the scope of this research activity. Resin injection will be conducted and the resulting strength restoration assessed in local fracture tests (end-notch flexure). The formation of actual impact damage morphologies, namely multiple planes of delamination interconnected with matrix cracks, is a critical aspect of this problem. Three 25-ply composite panel types having varying percentage of 0o fiber content have been impacted under low velocity at a range of energy levels. Resulting force vs. time and ultrasonic mapping of damage extent. Damage produced by such impacts will be used in subsequent injection repair studies. Intentional contamination will be introduced, and then removal will be achieved via injected solvents and atmospheric plasma, with monitoring of contaminant presence achieved by in-line quantitative chemical analysis. © 36th Technical Conference of the American Society for Composites 2021: Composites Ingenuity Taking on Challenges in Environment-Energy-Economy, ASC 2021.

关键词： Restoration

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Bacterial Mobility and Motility in Porous Media Mimicked By Microspheres

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SSRN 2022年

作者： Shrestha, Diksha Ou, Jun Rogers, Ariel Jereb, Amani Wang, Yong Department of Physics Cell and Molecular Graduate Program Materials Science and Engineering Program University of Arkansas FayettevilleAR72701 United States Department of Environmental Resources Engineering Mechanical Engineering Program California State Polytechnic University Humboldt ArcataCA95521 United States

Bacterial motion in porous media are essential for their survival, proper functioning, and variousapplications. Here we investigated the motion of Escherichia coli bacteria in microsphere-mimicked porousmedia. We observed reduced bacterial velocity and enhanced directional changes of bacteria as the densityof microspheres increased, while such changes happened mostly around the microspheres and due to thecollisions with the microspheres. More importantly, we established and quantified the correlation betweenthe bacterial trapping in porous media and the geometric confinement imposed by the microspheres. In addition,numerical simulations showed that the active Brownian motion model in the presence of microspheresresulted in bacterial motion that are consistent with the experimental observations. Our study suggested thatit is important to distinguish the ability of bacteria to move easily – bacterial mobility – from the abilityof bacteria to move independently – bacteria motility. Our results showed that bacterial motility remainssimilar in porous media, but bacterial mobility was significantly affected by the pore-scale confinement. © 2022, The Authors. All rights reserved.

关键词： Microspheres

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Emergent Magnetic Phases and Piezomagnetic Effects in MnxNi1−xF2 Thin Film Alloys

arXiv

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arXiv 2023年

作者： Van Haren, Ryan Hald, Nessa Lederman, David Department of Physics University of California Santa Cruz Santa CruzCA95064 United States Materials Science and Engineering Program School for Engineering of Energy Matter and Transport Arizona State University TempeAZ85287 United States

The effect of random competing single-ion anisotropies in antiferromagnets was studied using epitaxial MnxNi1−xF2 antiferromagnetic thin film alloys grown via molecular beam epitaxy. The crystal structure of this material is tetragonal for all values of x, and the Mn sites have a magnetic easy axis single-ion anisotropy while the Ni sites have an easy plane anisotropy perpendicular to the Mn easy axis. Crystallographic and magnetization measurements demonstrated that the thin film alloys were homogeneously mixed and did not phase-separate into their constituent parts. Pure MnF2 thin films epitaxially grown on MgF2 exhibited compressive strain along all three crystallographic axes which resulted in piezomagnetic effects. The piezomagnetism disappeared if the film was grown on a (MnNi)F2 graded buffer layer. A mean-field theory fit to the transition temperature as a function of the Mn concentration x, which takes into account piezomagnetic effects, gave a magnetic exchange constant between Mn and Ni ions of JMnNi = 0.305±0.003 meV. Mean-field theory calculations also predicted the existence of an oblique antiferromagnetic phase in the MnxNi1−xF2 alloy which agreed with the experimental data. A magnetic phase diagram for MnxNi1−xF2 thin film alloys was constructed and showed evidence for the existence of two unique magnetic phases, in addition to the ordinary antiferromagnetic and paramagnetic phases: an oblique antiferromagnetic phase, and an emergent magnetic phase proposed to be either a magnetic glassy phase or a helical phase. The phase diagram is quantitatively different from that of FexNi1−xF2 because of the much larger single-ion anisotropy of Fe2+ compared to Mn2+ © 2023, CC BY.

关键词： Ions

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Empowering Machines to Think Like Chemists: Unveiling Molecular Structure-Polarity Relationships with Hierarchical Symbolic Regression

arXiv

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arXiv 2024年

作者： Lou, Siyu Liu, Chengchun Chen, Yuntian Mo, Fanyang Department of Computer Science and Engineering Shanghai Jiao Tong University Shanghai200240 China Ningbo Institute of Digital Twin Eastern Institute of Technology Ningbo315200 China School of Materials Science and Engineering Peking University Beijing100871 China -Preferred Program Peking University Shenzhen Graduate School Shenzhen518500 China

Thin-layer chromatography (TLC) is a crucial technique in molecular polarity analysis. Despite its importance, the interpretability of predictive models for TLC, especially those driven by artificial intelligence, remains a challenge. Current approaches, utilizing either high-dimensional molecular fingerprints or domain-knowledge-driven feature engineering, often face a dilemma between expressiveness and interpretability. To bridge this gap, we introduce Unsupervised Hierarchical Symbolic Regression (UHiSR), combining hierarchical neural networks and symbolic regression. UHiSR automatically distills chemical-intuitive polarity indices, and discovers interpretable equations that link molecular structure to chromatographic behavior. Copyright © 2024, The Authors. All rights reserved.

关键词： Thin layer chromatography

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Efficient Predictions of Formation Energies and Convex Hulls from Density Functional Tight Binding Calculations

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SSRN 2022年

作者： Kumar, Anshuman Ali, Zulfikhar A. Wong, Bryan M. Materials Science & Engineering Program University of California Riverside RiversideCA92521 United States Department of Physics & Astronomy University of California Riverside RiversideCA92521 United States Materials Science & Engineering Program Department of Chemical & Environmental Engineering Department of Physics & Astronomy Department of Chemistry University of California Riverside RiversideCA92521 United States

Defects in materials significantly alter their electronic and structural properties, which affect the performance of electronic devices, structural alloys, and functional materials. However, calculating all the possible defects in complex materials with conventional Density Functional Theory (DFT) can be computationally prohibitive. To enhance the efficiency of these calculations, we interfaced Density Functional Tight Binding (DFTB) with the Clusters Approach to Statistical Mechanics (CASM) software package for the first time to calculate formation energies and convex hulls. Using SiC and ZnO as representative examples, we show that DFTB gives accurate results and can be a computationally cheaper alternative to DFT. Our DFTB+CASM implementation allows for an efficient exploration (up to an order of magnitude faster than DFT) of formation energies and convex hulls, which researchers can use to probe other complex systems. © 2022, The Authors. All rights reserved.

关键词： Density functional theory

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Charge-Carrier Dynamics and Relaxation in Cs2SnI6 Perovskite for Energy Storage: Existence of Anharmonic Rattling-Assisted Polaron Dynamics

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Physical Review Applied 2023年第5期20卷 054032-054032页

作者： Moumita Ghosh Pulak Pal Tufan Paul Soumen Maiti Souvik Bhattacharjee Kausik Sardar Aditi Sahoo Aswini Ghosh Kalyan Kumar Chattopadhyay Departments of Physics Jadavpur University Kolkata 700032 India School of Materials Science and Nanotechnology Jadavpur University Kolkata 700032 India Department of Physics St. Thomas College of Engineering & Technology Kolkata 700023 India Advanced Mechanical and Materials Characterization Division CSIR-Central Glass & Ceramic Research Institute Kolkata 700032 India School of Physical Sciences Indian Association for the Cultivation of Science Jadavpur Kolkata 700032 India

We have explored different aspects of charge-carrier dynamics and relaxation in lead-free Cs2SnI6 double perovskite using dielectric spectroscopy and assessed its electrochemical response. The cubic phase (Fm3¯m) with a lattice constant of 11.644 Å is confirmed for synthesized perovskite. The phonon dispersion illustrated by density-functional theory indicates the existence of soft optical modes triggered by anharmonic rattling of Cs atoms and dynamical rotation of SnI6 octahedra. Complex impedance spectra have provided details of the contributions of grain boundaries, grains, and anharmonic rattling to charge-carrier dynamics. The Cs2SnI6 exhibits electrical conductivity of 3.77×10−5Scm−1 at ambient conditions. The values of the power-law exponent for all temperatures suggest superlinear power-law (SPL) behavior of the ac conductivity. The relaxation time and the stretched exponent in the Kohlrausch-Williams-Watts (KWW) function of the electric modulus are caused by charge-carrier short-range mobility and the hopping of rattling-assisted polarons. The supercapacitor fabricated with Cs2SnI6 as the electrode has delivered a specific capacitance of 3830 F g−1 at a current density of 2 A g−1. A quasi-solid-state asymmetric supercapacitor device was also fabricated, which delivered an energy density of 51 Wh kg−1 and a power density as high as 852 W kg−1 at a current density of 1 A g−1. We believe this work will open up the avenue to another generation of lead-free, perovskite-based, sustainable energy-storage systems.

关键词： Carrier dynamics Dielectric properties Impedance Polarons Supercapacitors Energy materials Perovskites Semiconductor compounds

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Influence of Crystallographic Orientation on the Deformation of Ag Nanoparticles During High-Speed Impact

SSRN

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SSRN 2022年

作者： Becker, Michael F. Kovar, Desiderio Chitrakar, T.V. The University of Texas at Austin AustinTX78712 United States Materials Science and Engineering Program Texas Materials Institute United States Department of Electrical and Computer Engineering United States Department of Mechanical Engineering Center for Additive Manufacturing and Design Innovation

Several related aerosol processes utilize high velocity impact of solid nanoparticles to produce nanograined films including the aerosol deposition method, jet molding, vacuum kinetic spraying, and micro cold spray. Although the influence of important variables such as particle size and particle impact velocity, on particle deformation and film formation have been previously explored, other variables have not been systematically explored. Because particles impact with a full range of orientations, an understanding of the effect of particle orientation is required to predict film microstructures. Molecular dynamics simulations were conducted to determine the influence of particle crystallographic orientation on the particle deformation upon impact and the resulting microstructure of the deposit. We show that the orientations that produce the largest overall particle deformation are not correlated to orientations where initiation of plastic deformation is easiest. Rather, the deformation is heterogenous and depends on the mechanisms responsible for deformation. Two deformation mechanisms are identified: 1) dislocation plasticity and 2) disordering followed by viscous flow. The fraction of the atoms in the impacting particle that experience permanent deformation by each mechanism is quantified as a function of particle orientation. The implications of the effects of particle crystallographic orientation on film microstructures are also discussed. © 2022, The Authors. All rights reserved.

关键词： Molecular dynamics

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