jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Ondrej Dyck | Jacob L. Swett | Andrew R. Lupini | Jan A. Mol | Stephen Jesse
Source: Small Methods (article, 2021-01-15)
Field: Materials Science — Surfaces, Coatings and Films

Imaging Secondary Electron Emission from a Single Atomic Layer Graphene-based devices hold promise for a wide range of technological applications. Yet characterizing the structure and the electrical properties of a material that is only one atomic layer thick still poses technical challenges. Recent investigations indicate that secondary-electron electron-beam-induced current (SE-EBIC) imaging can reveal subtle details regarding electrical conductivity and electron transport with high spatial resolution. Here, it is shown that the SEEBIC imaging mode can be used to detect suspended single layers of graphene and distinguish between different numbers of layers. Pristine and contaminated areas of graphene are also compared to show that pristine graphene exhibits a substantially lower SE yield than contaminated regions. This SEEBIC imaging mode may provide valuable information for the engineering of surface coatings where SE yield is a priority. Graphene ; Materials science ; Electron ; Nanotechnology ; Yield (engineering) ; Cathode ray ; Layer (electronics) ; Secondary electrons ; Image resolution ; Electrical resistivity and conductivity ; Optoelectronics ; Optics ; Composite material ; Physics Electron and X-Ray Spectroscopy Techniques ; Semiconductor materials and devices ; Integrated Circuits and Semiconductor Failure Analysis
Authors: Anders M. N. Niklasson
Source: The Journal of Chemical Physics (article, 2021-02-01)
Field: Materials Science — Materials Chemistry

Extended Lagrangian Born–Oppenheimer molecular dynamics for orbital-free density-functional theory and polarizable charge equilibration models Extended Lagrangian Born-Oppenheimer molecular dynamics (XL-BOMD) [A. M. N. Niklasson, Phys. Rev. Lett. 100, 123004 (2008)] is formulated for orbital-free Hohenberg-Kohn density-functional theory and for charge equilibration and polarizable force-field models that can be derived from the same orbital-free framework. The purpose is to introduce the most recent features of orbital-based XL-BOMD to molecular dynamics simulations based on charge equilibration and polarizable force-field models. These features include a metric tensor generalization of the extended harmonic potential, preconditioners, and the ability to use only a single Coulomb summation to determine the fully equilibrated charges and the interatomic forces in each time step for the shadow Born-Oppenheimer potential energy surface. The orbital-free formulation has a charge-dependent, short-range energy term that is separate from long-range Coulomb interactions. This enables local parameterizations of the short-range energy term, while the long-range electrostatic interactions can be treated separately. The theory is illustrated for molecular dynamics simulations of an atomistic system described by a charge equilibration model with periodic boundary conditions. The system of linear equations that determines the equilibrated charges and the forces is diagonal, and only a single Ewald summation is needed in each time step. The simulations exhibit the same features in accuracy, convergence, and stability as are expected from orbital-based XL-BOMD. Molecular dynamics ; Force field (fiction) ; Coulomb ; Physics ; Density functional theory ; Charge (physics) ; Polarizability ; Classical mechanics ; Periodic boundary conditions ; Statistical physics ; Chemistry ; Electron ; Quantum mechanics ; Boundary value problem ; Molecule Machine Learning in Materials Science ; Advanced Chemical Physics Studies ; Advanced NMR Techniques and Applications
Authors: Yongke Sun | Guanben Du | Yong Cao | Qizhao Lin | Lihui Zhong | Jian Qiu
Source: IEEE Access (article, 2021-01-01)
Field: Chemistry — Organic Chemistry

Wood Product Tracking Using an Improved AKAZE Method in Wood Traceability System Tracking of the wood product is an important technology in the trade activity of rare plants. Normally, the factories use Quick Response (QR) and Radio-Frequency Identification (RFID) to identify the individual wood product, but these technologies are not safe enough because they can be easily falsified. It can be seen that traditional methods are hard to catch the detail of the slim wood texture from the wood product. In this study, a novel method is employed to resolve these problems using a biometric feature on the surface of the real wood product to distinguish the individual wood product. AKAZE is used to extract the key-point of wood texture. A sub-area detection technique along with a serialization method is then developed to improve the rate of identification. The sub-area detection technique deals with picking out a sub-region in which there are enough AKAZE points as small as possible. The serialization method is also utilized to reduce the redundant process of feature extraction. The experimental results demonstrate that the values of accuracy, recall, and F1 reach 0.98, 0.96, and 0.96, respectively. The match time that uses serialized function is reduced to 1/3 of which has no application in the original image. The validated results also reveal that our proposed methodology improves the robustness of the wood product identification, and it can be used in Wood Traceability System (WTS) with the blockchain to resolve the digital trust problem and the fast distinction issues of the real wood product. Computer science ; Serialization ; Traceability ; Robustness (evolution) ; Product (mathematics) ; Identification (biology) ; Feature extraction ; Radio-frequency identification ; Process (computing) ; Computer vision ; Mathematics ; Computer security Wood and Agarwood Research ; Industrial Vision Systems and Defect Detection ; Advanced Image and Video Retrieval Techniques
Authors: Ramakrishnan Hariharan | Balasundaram Rathinam | Baskar Neelakandan | Radhakrishnan Beemaraj | Chellamuthu Kannan
Source: Hemijska industrija (article, 2021-01-01)
Field: Materials Science — Metals and Alloys

Surface modification method of duplex type stainless steels by the pack boriding process This work presents the investigation of a boriding process on two grades of stainless steel namely UNS32750 super duplex stainless steel and UNSS31803 duplex stainless steel in order to improve material properties and possibly to reduce catastrophic failure of industrial components. Usage of duplex stainless steels has become customary in the fields of oil and refinery, marine and pipeline applications due to increased corrosion resistance; however, these materials exhibit low wear characteristics. To overcome this problem, in this work the pack boriding process was employed. Evaluation of effects of the boriding process on the microstructure and mechanical properties was performed using scanning electron and optical microscopy, Vickers hardness tests and wear tests. It was shown that the 4 h process resulted in the greatest boriding layer thickness yielding the maximum surface hardness of 1407 HV in the super duplex stainless steel UNS32750 while this value was 1201 HV in the duplex stainless steel UNSS31803. Wear resistance of borided materials were up to 6-fold greater than those of non - treated materials. Also, the borided duplex materials were shown to be more suitable for industrial applications for valve and shaft components as compared to the boronized super duplex stainless steel. Boriding ; Materials science ; Metallurgy ; Duplex (building) ; Microstructure ; Corrosion ; Scanning electron microscope ; Boride ; Composite material Hydrogen embrittlement and corrosion behaviors in metals ; Metal and Thin Film Mechanics ; Corrosion Behavior and Inhibition
Authors: André Mateus | Mikhail M. Savitski | Ilaria Piazza
Source: Molecular Systems Biology (article, 2021-07-01)
Field: Chemistry — Spectroscopy

The rise of proteome‐wide biophysics While informative, protein amounts and physical protein associations do not provide a full picture of protein function. This Commentary highlights the potential of structural and stability proteomic technologies to derive new insights in biology and medicine. Biology ; Proteome ; Computational biology ; Protein function ; Protein stability ; Systems biology ; Proteomics ; Function (biology) ; Structural biology ; Bioinformatics ; Cell biology ; Biochemistry Advanced Proteomics Techniques and Applications ; Bioinformatics and Genomic Networks ; Microbial Metabolic Engineering and Bioproduction
Authors: Xiaodong Zhang | Zhao Hui Duan | Hanping Mao | Hongyan Gao | Zhiyu Zuo
Source: Ciência Rural (article, 2021-11-22)
Field: Chemistry — Analytical Chemistry

A lettuce moisture detection method based on terahertz time-domain spectroscopy ABSTRACT: For non-destructive detection of water stress in lettuce, terahertz time-domain spectroscopy (THz-TDS) was used to quantitatively analyze water content in lettuce. Four gradient lettuce water contents were used . Spectral data of lettuce were collected by a THz-TDS system, and denoised using the S-G derivative, Savitzky-Golay (S-G) smoothing and normalization filtering. The fitting effect of the pretreatment method was better than that of regression fitting, and the S-G derivative fitting effect was obtained. Then a calibration set and a verification set were divided by the Kennan-Stone algorithm, sample set partitioning based on joint X-Y distance (SPXY) algorithm, and the random sampling (RS) algorithm, and the parameters of RS were optimized by regression fitting. The stability competitive adaptive reweighted sampling, iteratively retained information variables and interval combination optimization were used to select characteristic wavelengths, and then continuous projection was used on basis of the three algorithms above. After the successive projection algorithm was re-screened, partial least squares regression was used into modeling. The regression coefficients Rc 2 and RMSEC reach 0.8962 and 412.5% respectively, and Rp 2 and RMSEP of the verification set are 0.8757 and 528.9% respectively. Mathematics ; Smoothing ; Calibration ; Sampling (signal processing) ; Normalization (sociology) ; Partial least squares regression ; Algorithm ; Projection (relational algebra) ; Statistics ; Computer science ; Detector Spectroscopy and Chemometric Analyses ; Advanced Chemical Sensor Technologies ; Spectroscopy Techniques in Biomedical and Chemical Research
Authors: Jinjun Bai | Wei Shen | Jia Shi | Wei Xu | Shusheng Zhang | Shengjiang Chang
Source: Micromachines (article, 2021-03-21)
Field: Materials Science — Electronic, Optical and Magnetic Materials

A Non-Volatile Tunable Terahertz Metamaterial Absorber Using Graphene Floating Gate Based on the graphene floating gate, a tunable terahertz metamaterial absorber is proposed. Compared with the traditional graphene-dielectric-metal absorber, our absorber has the property of being non-volatile and capacity for anti-interference. Using the finite element method, the paper investigates the absorption spectra, the electric field energy distribution, the tunability and the physical mechanism. In addition, we also analyse the influence of geometry, polarization and incident angles on the absorption. Simulation results show that the bandwidth of the absorption above 90% can reach up to 2.597 THz at the center frequency of 3.970 THz, and the maximum absorption can be tuned continuously from 14.405% to 99.864% by controlling the Fermi level from 0 eV to 0.8 eV. Meanwhile, the proposed absorber has the advantages of polarization insensitivity and a wide angle, and has potential applications in imaging, sensing and photoelectric detection. Metamaterial absorber ; Terahertz radiation ; Materials science ; Graphene ; Optoelectronics ; Metamaterial ; Photoelectric effect ; Polarization (electrochemistry) ; Electric field ; Absorption (acoustics) ; Dielectric ; Fermi energy ; Optics ; Tunable metamaterials ; Nanotechnology ; Physics ; Chemistry Metamaterials and Metasurfaces Applications ; Antenna Design and Analysis ; Plasmonic and Surface Plasmon Research
Authors: E. L. Martı́n | J.-Y. Zhang | P. Esparza | Félix Gracia | J. L. Rasilla | T. Masseron | Adam J. Burgasser
Source: Astronomy and Astrophysics (article, 2021-11-01)
Field: Chemistry — Spectroscopy

Ammonia-methane ratios from <i>H</i>-band near-infrared spectra of late-T and Y dwarfs Aims. Our goals are to investigate the relative absorption strengths of ammonia and methane using low-resolution H -band (1.5−1.7 microns) spectra obtained in the laboratory and compared with observational spectra of late-T and Y dwarfs, and to estimate what can be expected from the wide-angle low-resolution near-infrared spectroscopic survey that will be provided by the upcoming Euclid space mission. Methods. Gas cells containing ammonia and methane at atmospheric pressure were custom-made in our chemical laboratory. Low-resolution near-infrared spectroscopy of these gas cells was collected in our optical laboratory. It is compared with simulated spectra using the high-resolution transmission molecular absorption database (HITRAN) for temperatures of 300 K and 500 K, and with near-infrared spectra of late-T dwarfs, Y dwarfs, Jupiter, and Saturn. We selected for this investigation the spectral region between 1.5 and 1.7 microns ( H band) because it is covered by the Euclid red grism, it is particularly sensitive to the relative proportions of ammonia and methane opacity, and it is free from strong contributions of other abundant molecules, such as water vapor. Results. The laboratory spectra showed that the ammonia and methane features present in the simulations that used the HITRAN database are incomplete. Using our laboratory spectra, we propose a modified version of the NH3-H spectral ratio with expanded integration limits that increases the amplitude of variation in the index with respect to spectral type. Combinations of our laboratory spectra were used to find the best fits to the observed spectra with the relative absorption ratio of ammonia to methane as a free parameter. A relationship was found between the T eff and the ratio of ammonia to methane from spectral classes T5 to Y2 (1100 K–350 K), in fairly good qualitative agreement with theoretical predictions for high-gravity objects and temperatures from 1100 K to 500 K. The ammonia-to-methane ratios in late-T and Y dwarfs are similar to that of Jupiter, suggesting a similar chemical composition. Simulations of the spectroscopic performance of Euclid suggest that it will yield T eff values and ratios of ammonia to methane for over 10 3 late-T dwarfs in the entire wide survey. HITRAN ; Spectral line ; Methane ; Infrared spectroscopy ; Spectral resolution ; Infrared ; Absorption spectroscopy ; Analytical Chemistry (journal) ; Spectroscopy ; Chemistry ; Opacity ; Astrophysics ; Physics ; Optics ; Astronomy Spectroscopy and Laser Applications ; Atmospheric Ozone and Climate ; Astro and Planetary Science
Authors: Mariusz Adamski | M. Czechlowski | K. Durczak | Tomasz Garbowski
Source: Energies (article, 2021-12-09)
Field: Chemistry — Analytical Chemistry

Determination of the Concentration of Propionic Acid in an Aqueous Solution by POD-GP Model and Spectroscopy Biorefining and biorefineries are the future of industry and energy. It is still a long way to complete its implementation, but small biorefineries focused mainly on the production of fuels and energy are more and more frequent in rural areas and large areas located near big cities in which, in addition to fuels and energy, various organic substances of high market value are also produced. In order to optimize biogas production and to control methane fermentation processes, fast and accurate identification of carboxylic acid concentrations, including propionic acid as a precursor to acetic acid, is needed. In this study, a process quality control method was developed to evaluate the propionic acid content of an aqueous solution from the fermentation mass. The proposed methodology is based on near infrared spectroscopy with multivariate analysis and stochastic metamodeling with a denoising procedure based on proper orthogonal decomposition (POD). The proposed methodology uses the Bayesian theory, which provides additional information on the magnitude of the correlation between state and control variables. The calibration model was, therefore, constructed by using Gaussian Processes (GP) to predict propionic acid content in the aqueous solution using an NIR-Vis spectrophotometer. The design of the calibration model was based on absorbance spectra and calculation data from selected wavelength ranges from 305 nm to 2210 nm. Measurement data were first denoised and truncated to build a fast and reliable metamodel for precise identification of the acid content of an aqueous solution at a concentration from 0 to 5.66%. The mean estimation error generated by the metamodel does not exceed 0.7%. Aqueous solution ; Process engineering ; Biological system ; Chemistry ; Computer science ; Environmental science ; Engineering ; Organic chemistry Spectroscopy and Chemometric Analyses ; Spectroscopy Techniques in Biomedical and Chemical Research ; Fault Detection and Control Systems
Authors: Sara B. Isbill | Ashley E. Shields | Delis J. Mattei-Lopez | Roger Kapsimalis | J. L. Niedziela
Source: Computational Materials Science (article, 2021-04-26)
Field: Materials Science — Materials Chemistry

Reviewing computational studies of defect formation and behaviors in carbon fiber structural units Graphene ; Materials science ; Carbon fibers ; Graphite ; Nanotechnology ; Structural material ; Carbon nanotube ; Density functional theory ; Structural stability ; Computational chemistry ; Chemistry ; Structural engineering ; Composite material ; Composite number Graphene research and applications ; Fiber-reinforced polymer composites ; Advancements in Battery Materials
Authors: Jieyun Bai | Yaosheng Lu | Yijie Zhu | Huijun Wang | Dechun Yin | Henggui Zhang | Diego Franco | Jichao Zhao
Source: International Journal of Molecular Sciences (review, 2021-07-19)
Field: Materials Science — Materials Chemistry

Understanding PITX2-Dependent Atrial Fibrillation Mechanisms through Computational Models Atrial fibrillation (AF) is a common arrhythmia. Better prevention and treatment of AF are needed to reduce AF-associated morbidity and mortality. Several major mechanisms cause AF in patients, including genetic predispositions to AF development. Genome-wide association studies have identified a number of genetic variants in association with AF populations, with the strongest hits clustering on chromosome 4q25, close to the gene for the homeobox transcription PITX2. Because of the inherent complexity of the human heart, experimental and basic research is insufficient for understanding the functional impacts of PITX2 variants on AF. Linking PITX2 properties to ion channels, cells, tissues, atriums and the whole heart, computational models provide a supplementary tool for achieving a quantitative understanding of the functional role of PITX2 in remodelling atrial structure and function to predispose to AF. It is hoped that computational approaches incorporating all we know about PITX2-related structural and electrical remodelling would provide better understanding into its proarrhythmic effects leading to development of improved anti-AF therapies. In the present review, we discuss advances in atrial modelling and focus on the mechanistic links between PITX2 and AF. Challenges in applying models for improving patient health are described, as well as a summary of future perspectives. PITX2 ; Atrial fibrillation ; Homeobox ; Bioinformatics ; Chromosome ; Medicine ; Computational biology ; Neuroscience ; Transcription factor ; Biology ; Cardiology ; Gene ; Genetics Corrosion Behavior and Inhibition ; Hydrogen embrittlement and corrosion behaviors in metals ; Cancer-related gene regulation
Authors: Melisa Lázaro | Roberto Melero | Charlotte Huet | Jorge P. López‐Alonso | Sandra Delgado | Alexandra Dodu | Eduardo M. Bruch | Luciano A. Abriata | Pedro M. Alzari | Mikel Valle | María‐Natalia Lisa
Source: Communications Biology (article, 2021-06-03)
Field: Materials Science — Materials Chemistry

3D architecture and structural flexibility revealed in the subfamily of large glutamate dehydrogenases by a mycobacterial enzyme Glutamate dehydrogenases (GDHs) are widespread metabolic enzymes that play key roles in nitrogen homeostasis. Large glutamate dehydrogenases composed of 180 kDa subunits (L-GDHs<sub>180</sub>) contain long N- and C-terminal segments flanking the catalytic core. Despite the relevance of L-GDHs<sub>180</sub> in bacterial physiology, the lack of structural data for these enzymes has limited the progress of functional studies. Here we show that the mycobacterial L-GDH<sub>180</sub> (mL-GDH<sub>180</sub>) adopts a quaternary structure that is radically different from that of related low molecular weight enzymes. Intersubunit contacts in mL-GDH<sub>180</sub> involve a C-terminal domain that we propose as a new fold and a flexible N-terminal segment comprising ACT-like and PAS-type domains that could act as metabolic sensors for allosteric regulation. These findings uncover unique aspects of the structure-function relationship in the subfamily of L-GDHs. Enzyme ; Allosteric regulation ; Subfamily ; Biochemistry ; Biology ; Glutamate dehydrogenase ; Glutamate receptor ; Receptor ; Gene Enzyme Structure and Function ; Amino Acid Enzymes and Metabolism ; Bacterial Genetics and Biotechnology
Authors: Jevrem Stojanović | Jovana Krmar | Ana Protić | Bojana Svrkota | Nevena Đajić | Biljana Otašević
Source: Arhiv za farmaciju (article, 2021-01-01)
Field: Chemistry — Spectroscopy

Experimental design in HPLC separation of pharmaceuticals Design of Experiments (DoE) is an indispensable tool in contemporary drug analysis as it simultaneously balances a number of chromatographic parameters to ensure optimal separation in High Pressure Liquid Chromatography (HPLC). This manuscript briefly outlines the theoretical background of the DOE and provides step-by-step instruction for its implementation in HPLC pharmaceutical practice. It particularly discusses the classification of various design types and their possibilities to rationalize the different stages of HPLC method development workflow, such as the selection of the most influential factors, factors optimization and assessment of the method robustness. Additionally, the application of the DOE-based Analytical Quality by Design (AQbD) concept in the LC method development has been summarized. Recent achievements in the use of DOE in the development of stability-indicating LC and hyphenated LC-MS methods have also been briefly reported. Performing of Quantitative structure retention relationship (QSRR) study enhanced with DOE-based data collection was recomended as a future perspective in description of retention in HPLC system. Quality by Design ; High-performance liquid chromatography ; Design of experiments ; Chromatography ; Workflow ; Computer science ; Robustness (evolution) ; Chromatographic separation ; Biochemical engineering ; Chemistry ; Process engineering ; Mathematics ; Engineering Analytical Chemistry and Chromatography ; Analytical Methods in Pharmaceuticals ; Microfluidic and Capillary Electrophoresis Applications