jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: M. Srinivas | P. Rama Chandra Prasad
Source: Journal of Environmental Informatics Letters (article, 2023-01-01)
Field: Chemistry — Analytical Chemistry

Modeling Uncertainty Quantification of NDVI of Agricultural Fields through Bayesian Linear Regression in Time Series Prediction The current research discusses the applications of Bayesian linear regression to predict the uncertainty of remote sensing data. To predict the uncertainty, the study considered the SENTINEL-2 satellite data of agricultural fields of Uttar Pradesh state of India. Using the stratified sampling method in Google Earth Engine, the random points generated are mapped to agricultural fields. Data was collected in the form of maximum Normalized Difference Vegetation Index (NDVI) values of each agricultural field. The dynamics of the time series predictions were explored with Bayesian linear regression, a probabilistic deep learning method. The model uncertainty defined as epistemic uncertainty is evaluated with the prior and posterior probability parameters of Bayesian statistics in linear regression. The number of regression lines predicted for the same data shows evidence of uncertainty. The Bayesian linear regression models show evidence of high uncertainty for the predicted NDVI values. The variation in model uncertainty is measured by dividing the dataset into samples and it is observed that with increase in data the uncertainty is reduced. Also, with the increase in data, the posterior density becomes sharper which corresponds to a decrease in variance. Further, the study extended the concept of regression analysis with Gaussian basis functions to determine the effect of model uncertainty with an increase in data. The analysis has shown the same result in knowing the effect of uncertainty with the increase in data. Further, a nonlinear polynomial regression model with a Gaussian distribution as a basis function was developed to evaluate the marginal probabilities of the evidence function in capturing the uncertainty with varying degrees of freedom. The polynomial regression with a Gaussian distribution using Bayesian statistics has captured the uncertainty and confirmed that the uncertainty is captured at lower degrees of freedom. Bayesian linear regression ; Normalized Difference Vegetation Index ; Statistics ; Mathematics ; Linear regression ; Bayesian probability ; Regression analysis ; Polynomial regression ; Bayesian multivariate linear regression ; Bayesian inference ; Econometrics ; Leaf area index Spectroscopy and Chemometric Analyses ; Smart Agriculture and AI ; Remote Sensing in Agriculture
Authors: Banaz Omer Ahmad | Kamal M. Mahmoud
Source: Journal of Kufa for Chemical Sciences (article, 2023-08-28)
Field: Chemistry — Analytical Chemistry

Determination of Caffeine and Few Metals in Halabja Tea and Comparing with Various Tea Samples in Erbil Markets This paper deals with two main parts: part (I) performed the caffeine levels evaluation in three commercial tea leaves (black, green, and herbal tea) in Erbil markets and Halabja city. The caffeine was extracted by liquid-liquid extraction using dichloromethane and chloroform solvents. The extracted caffeine was purified, and then identified by melting point (M.P), ultraviolet (UV) and Fourier transform infrared (FT-IR) spectroscopy that provides spectra identical to the standard caffeine crystals. The level of caffeine in black tea was found greater than in green tea, presumably because black tea are made of older tea leaves, in contrast, there is no caffeine obtained from Halabja tea. Part (II) mentioned the determination of metal ions (lithium, sodium, potassium, and calcium) in 5 brands of black and green tea (leaves and bags) in addition to Halabja tea; using flame atomic emission (FAES) and flame atomic absorption (FAAS) spectroscopy. The tea beverages were prepared by three different methods: (chemically, infusion, and continuous infusion). There was a moderate quantity of sodium, potassium, and calcium was determined in the 5 brands of tea, while lithium found in the trace. Halabja tea was free from caffeine while lithium, sodium, potassium, and calcium elements of the Halabja herbal tea are all higher than all the other types of tea leaves and bags Caffeine ; Chemistry ; Potassium ; Black tea ; Sodium ; Green tea ; Dichloromethane ; Lithium (medication) ; Chromatography ; Food science ; Biochemistry ; Organic chemistry ; Solvent Heavy Metals in Plants ; Tea Polyphenols and Effects
Authors: Sara Tasnim
Source:  (article, 2023-01-01)
Field: Chemistry — Analytical Chemistry

QUANTITATIVE ANALYTICAL VALIDATION OF HERBAL DRUG FORMULATIONS USING UPLC AND UV-VISIBLE SPECTROSCOPY: ACCURACY, PRECISION, AND STABILITY ASSESSMENT This systematic review evaluates how ultra-performance liquid chromatography and UV–Visible spectrophotometry deliver quantitative analytical validation for finished herbal drug formulations, with emphasis on accuracy, precision, and stability. Following a protocol driven PRISMA process, records were de duplicated, screened in two stages by independent reviewers, and appraised with an Analytical Validation Quality Score to assess reporting completeness, validation coverage, statistical rigor, matrix handling, and stability depth, ensuring transparent selection and high reproducibility across data extraction and synthesis. In total, 115 articles met eligibility and were analyzed, contributing 204 method–analyte–matrix entries and 1,156 validation effects that encompassed recovery at defined spike levels, repeatability and intermediate precision, and multiple stability modalities. Across the corpus, pooled recovery centered at 99.3 percent, with narrow prediction intervals that indicate fit for purpose trueness in complex matrices, and repeatability clustered around practical laboratory thresholds. Platform comparisons showed a consistent but modest advantage for UPLC on tight accuracy and precision bands, while UV–Vis reached broadly acceptable performance when spectral selectivity and matrix aware calibration were emphasized; joint success across accuracy, repeatability, and at least one stability modality reached 81.4 percent overall, rising to 87.5 percent for UPLC. Design choices such as derivative or ratio derivative approaches with standard addition improved UV–Vis outcomes in liquid preparations. The evidence indicates that both platforms, paired with disciplined calibration, matrix aware sample preparation, and stability indicating design, can reliably support routine quality control and stability studies in herbal products. Repeatability ; Reproducibility ; Calibration ; Stability (learning theory) ; Protocol (science) ; Matrix (chemical analysis) ; Accuracy and precision ; High-performance liquid chromatography Spectroscopy and Chemometric Analyses ; Metabolomics and Mass Spectrometry Studies ; Pesticide Residue Analysis and Safety
Authors: Simona Silvia Merola | Christian Antetomaso | Adrian Irimescu | Bianca Maria Vaglieco | Simona Di Micco | Elio Jannelli
Source:  (article, 2023-01-01)
Field: Materials Science — Surfaces, Coatings and Films

3D CFD Simulation of Water Droplet Dynamics on a Fuel Cell Gas Diffusion Layer by Considering a Realistic Woven Structure Proton exchange membrane fuel cells have been identified as suitable for vehicle implementation. As for all fuel cell types, thermal management is a critical issue: the redox reactions taking place in the membrane electrode assembly generate water; a humid membrane is able to enhance transport phenomena, but too much water could flood the pathways of reactant gases. Recently, interest has grown with respect to the properties of the gas diffusion layer of membranes: its fibres pattern can critically affect water removal rates. Computation fluid dynamics represents a powerful tool that can be used for understanding the key design factors of fuel cell components to improve the overall performance. Specifically, in the case of the diffusion layer, 3D simulation can investigate droplet dynamics and define the optimized surface structure for water management. In this paper, optical data and numerical results were combined to characterize the behaviour (oscillation, detachment, etc) of a couple of droplets on the woven gas diffusion layer with a structure retrieved by using an approach typical of the textile industry. High-spatial resolution imaging allowed the evaluation of warp/weft size; these parameters were used for building the 3D mesh for simulations based on the Volume of fluid method. The dynamics of droplets, with diameters ranging from 200 to 600 m, were investigated under the effect of a constant 10 m/s airflow for different gas diffusion layer geometries. In addition, the cases of the droplet pairs, deposited at different reciprocal distances, were studied by using the same methodological approach. Results demonstrated the impact of layer structure on the results obtained through simulations; moreover, an optimised design can contribute to control water removal and minimise flooding effects. Proton exchange membrane fuel cell ; Computational fluid dynamics ; Diffusion ; Gaseous diffusion ; Materials science ; Water transport ; Membrane ; Mechanics ; Mechanical engineering ; Fuel cells ; Chemical engineering ; Environmental science ; Chemistry ; Water flow ; Thermodynamics ; Environmental engineering ; Engineering ; Physics Surface Modification and Superhydrophobicity ; Fuel Cells and Related Materials ; Electrospun Nanofibers in Biomedical Applications
Authors: Yingying Shi | Ming Zhou | Min Kou | Kailin Zhang | Xianyi Zhang | Xianglei Kong
Source: Frontiers in Chemistry (article, 2023-03-09)
Field: Chemistry — Spectroscopy

Simultaneous quantitative chiral analysis of four isomers by ultraviolet photodissociation mass spectrometry and artificial neural network Although mass spectrometry (MS) has its unique advantages in speed, specificity and sensitivity, its application in quantitative chiral analysis aimed to determine the proportions of multiple chiral isomers is still a challenge. Herein, we present an artificial neural network (ANN) based approach for quantitatively analyzing multiple chiral isomers from their ultraviolet photodissociation mass spectra. Tripeptide of GYG and iodo-L-tyrosine have been applied as chiral references to fulfill the relative quantitative analysis of four chiral isomers of two dipeptides of <sup><i>L/D</i></sup> His <sup><i>L/D</i></sup> Ala and <sup><i>L/D</i></sup> Asp <sup><i>L/D</i></sup> Phe, respectively. The results show that the network can be well-trained with limited sets, and have a good performance in testing sets. This study shows the potential of the new method in rapid quantitative chiral analysis aimed at practical applications, with much room for improvement in the near future, including selecting better chiral references and improving machine learning methods. Photodissociation ; Mass spectrometry ; Tripeptide ; Artificial neural network ; Ultraviolet ; Chemistry ; Chirality (physics) ; Biological system ; Computer science ; Chromatography ; Artificial intelligence ; Materials science ; Amino acid ; Physics ; Organic chemistry Mass Spectrometry Techniques and Applications ; Analytical Chemistry and Chromatography ; Advanced Proteomics Techniques and Applications
Authors: Fei Liu | Yan Zhang | Xiu Qin Li | Yan Gao | Kang Li | Qing He Zhang
Source: Research Square (preprint, 2023-07-07)
Field: Chemistry — Spectroscopy

Generic and accurate prediction of retention times in liquid chromatography by post-projection calibration Calibration ; Projection (relational algebra) ; Chromatography ; Computer science ; Artificial intelligence ; Chemistry ; Mathematics ; Statistics ; Algorithm Analytical Chemistry and Chromatography ; Metabolomics and Mass Spectrometry Studies ; Chromatography in Natural Products
Authors: Fei Yi | Junyu Li | Jinzhao Li
Source:  (preprint, 2023-11-27)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Particle swarm optimization of multilayer multi-sized metamaterial absorber for long-wave infrared polarimetric imaging Infrared polarization imaging holds significant promise for enhancing target recognition in both civil and defense applications. The Division of Focal Plane (DoFP) scheme has emerged as a leading technology in the field of infrared polarization imaging due to its compact design and absence of moving parts. However, traditional DoFP solutions primarily rely on micropolarizer arrays, necessitating precise alignment with the focal plane array and leading to challenges in alignment and the introduction of optical crosstalk. Recent research has sought to augment the performance of infrared detectors and enable polarization and spectral selection by integrating metamaterial absorbers with the pixels of the detector. Nevertheless, the results reported so far exhibit shortcomings, including low polarization absorption rates and inadequate polarization extinction ratios. Furthermore, there is a need for a comprehensive figure of merit to assess the performance of polarization-selective thermal detectors systematically. In this study, we employ the particle swarm optimization algorithm to present a multilayer, multi-sized metamaterial absorber capable of achieving a remarkable polarization-selective absorption rate of up to 87.2% across the 8-14 μm spectral range. Moreover, we attain a polarization extinction ratio of 38.51. To elucidate and predict the resonant wavelengths of the structure, we propose a modified equivalent circuit model. Our analysis employs optical impedance matching to unveil the underlying mechanisms responsible for the high absorption. We also introduce a comprehensive figure of merit to assess the efficacy of infrared polarization detection through the integration of metamaterials with microbolometers. Finally, drawing on the proposed figure of merit, we suggest future directions for improving integrated metamaterial absorber designs, with the potential to advance practical mid-infrared polarization imaging technologies. Metamaterial ; Figure of merit ; Polarization (electrochemistry) ; Optics ; Cardinal point ; Polarimetry ; Detector ; Infrared ; Metamaterial absorber ; Extinction ratio ; Physics ; Optoelectronics ; Wavelength ; Scattering ; Tunable metamaterials Metamaterials and Metasurfaces Applications ; Polydiacetylene-based materials and applications ; Optical Polarization and Ellipsometry
Authors: Yue Sun | Sándor Brockhauser | Péter Hegedűs | Christian Plückthun | Luca Gelisio | D. E. Ferreira de Lima
Source: Research Square (preprint, 2023-02-28)
Field: Materials Science — Materials Chemistry

Self-Supervised Approaches to the Classification of Spectra: Application to Phase Transitions in X-ray Diffraction Data Abstract The ability to detect interesting events is instrumental to effectively steer experiments and maximize their scientific efficiency. To address this, here we introduce and validate three frameworks based on self-supervised learning which are capable of classifying 1D spectral data using a limited amount of labeled data. In particular, in this work we focus on the identification of phase transitions in samples investigated by x-ray diffraction. We demonstrate that the three frameworks, based either on relational reasoning, contrastive learning, or a combination of the two, are capable of accurately identifying phase transitions. Furthermore, we discuss in detail the selection of data augmentations, crucial to ensure that scientifically meaningful information is retained. Computer science ; Focus (optics) ; Identification (biology) ; Artificial intelligence ; Diffraction ; Machine learning ; Selection (genetic algorithm) ; Phase (matter) ; Supervised learning ; Phase transition ; Pattern recognition (psychology) ; Data mining ; Physics ; Optics ; Artificial neural network ; Biology Machine Learning in Materials Science ; X-ray Diffraction in Crystallography ; Domain Adaptation and Few-Shot Learning
Authors: S.S. Shaikh | Suryakant B. Borul | Shahebaz Sakhawat Khan
Source: International Journal of Engineering Technology and Management Sciences (article, 2023-01-01)
Field: Materials Science — Materials Chemistry

A Study on the Gamma-ray Attenuation coefficient Parameters for Potassium Carbonate The linear attenuation coefficient (LAC) and mass attenuation coefficient (MAC) are most important while studying of radiation, radio-isotopes in dosimentry and irradiation of materials. In the present work to calculate linear attenuation coefficient (LAC) and mass attenuation coefficient (MAC) values of different salts samples by using Gamma-ray spectrometry with Photo-Multiplier Tube (PMT) and Multi-Channel Analyzer (MCA). The 0.123, 0.511, 0.662, 1.17, 1.28 and 1.33MeV gamma energy rays used for the experiment in the interaction of Potassium carbonate salt samples and compared the Mass attenuation coefficient (MAC) values of salt samples. The obtained gamma-ray spectra were analyzed using computer software. Attenuation coefficient ; Attenuation ; Mass attenuation coefficient ; Analytical Chemistry (journal) ; Gamma ray ; Radiation ; Radiochemistry ; Potassium ; Mass spectrometry ; Materials science ; Chemistry ; Optics ; Physics ; Nuclear physics Radiation Shielding Materials Analysis ; Advanced X-ray and CT Imaging ; Radiation Dose and Imaging
Authors: Tucker Carrington | Nuoyan Yang | Spencer Hill | Sergei Manzhos
Source: ChemRxiv (preprint, 2023-02-08)
Field: Chemistry — Organic Chemistry

A local Gaussian Processes method for fittingpotential surfaces that obviates the need to invertlarge matrices In order to compute a vibrational spectrum, one often wishes to start with a set of ab initio Born-Oppenheimer potential values at points, called fitting points, and interpolate or fit to find values of the potential at quadrature or collocation points. It is common to do this once to build a potential energy surface (PES). Once the PES is known, it can be evaluated at any point in configuration space. Gaussian Process (GP) is frequently being used to make a PES. As is the case in other interpolation methods, to use GP one must store and invert a matrix whose size is the number of fitting points. The matrix is sometimes large enough that approximations are introduced to reduce the cost of the calculation. We show that is possible to use many local Gaussian Process fits rather than one global fit. Retaining only local Gaussians and the associated points works well despite the fact that other Gaussians have tails with significant amplitude in the local region. We demonstrate that from the potential values obtained from the local fits it is possible to compute accurate energy levels of formaldehyde. In one calculation, potential values were obtained with N = 120, 000 fitting points by inverting matrices of size less than m = 400. The local idea reduces the cost from N^3 to T(m3 + N), where T is the number of desired potential points. Interpolation (computer graphics) ; Potential energy ; Gaussian process ; Gaussian ; Kriging ; Potential energy surface ; Mathematics ; Superposition principle ; Matrix (chemical analysis) ; Determinantal point process ; Random matrix ; Applied mathematics ; Mathematical analysis ; Computer science ; Ab initio ; Physics ; Quantum mechanics ; Statistics Chemical Thermodynamics and Molecular Structure ; Spectroscopy and Laser Applications ; Gaussian Processes and Bayesian Inference
Authors: Huawei Liu | Peng He | Wentao Li | Wei Sun | Kai Shi | Youqin Wang | Qian‐Kun Mo | Xinyu Zhang | Shou‐Fei Zhu
Source: Angewandte Chemie (article, 2023-09-12)
Field: Chemistry — Organic Chemistry

Catalyst‐Oriented Design Based on Elementary Reactions (CODER) for Triarylamine Synthesis Abstract Recently, the application of computational tools to the rational design of catalysts has received considerable attention, but progress has been limited by the reliance on databases and because mechanistic data have been almost neglected. Herein, we report a new strategy for catalyst design, designated c atalyst‐ o riented d esign based on e lementary r eactions (CODER), which fully utilizes mechanistic data, combines the strengths of computational tools and researcher experience. CODER enabled the development of extremely efficient Pd catalysts for C−N coupling, which markedly improved the efficiency of the synthesis of widely used triarylamine optoelectronic materials by enhancing the turnover numbers (up to 340000) to 1–3 orders of magnitude towards literature values. Catalysis ; Computer science ; Rational design ; Coupling (piping) ; Combinatorial chemistry ; Nanotechnology ; Chemistry ; Materials science ; Organic chemistry Catalytic Cross-Coupling Reactions ; Nanocluster Synthesis and Applications ; Nanomaterials for catalytic reactions
Authors: Jianan Zhang | Aditya Koneru | Subramanian K. R. S. Sankaranarayana | Carmen M. Lilley
Source: arXiv (Cornell University) (preprint, 2023-09-29)
Field: Materials Science — Materials Chemistry

Evolutionary Search and Theoretical Study of Silicene Grain Boundaries' Mechanical Properties Defects such as grain boundaries (GBs) are almost inevitable during the synthesis process of 2D materials. To take advantage of the fascinating properties of 2D materials, understanding the nature and impact of various GB structures on the pristine 2D sheet is crucial. In this work, using an evolutionary algorithm search, we predict a wide variety of silicene GB structures with very different atomic structures compared to those found in graphene or hexagonal boron-nitride. Twenty-one GBs with the lowest energy were validated by density functional theory (DFT) - a majority of which were previously unreported to our best knowledge. Based on the diversity of the GB predictions, we found that the formation energy and mechanical properties can be dramatically altered by adatoms positions within a GB and certain types of atomic structures, such as four-atom rings. To study the mechanical behavior of these GBs, we apply strain to the GB structures stepwise and use DFT calculations to investigate the mechanical properties of 9 representative structures. It is observed that GB structures based on pentagon-heptagon pairs are likely to have similar or higher in-plane stiffness and strength compared with the zigzag orientation of pristine silicene. However, an adatom located at the hollow site of a heptagon ring can significantly deteriorate the mechanical strength. For all the structures, the in-plane stiffness and strength were found to decrease with increasing formation energy. For the failure behavior of GB structures, it was found that GB structures based on pentagon-heptagon pairs have failure behavior similar to graphene. We also found that the GB structures with atoms positioned outside of the 2D plane tend to experience phase transitions before failure. Utilizing the evolutionary algorithm, we locate diverse silicene GBs and obtain useful information for their mechanical properties. Silicene ; Materials science ; Density functional theory ; Graphene ; Zigzag ; Stiffness ; Grain boundary ; Boron nitride ; Atom (system on chip) ; Crystallography ; Nanotechnology ; Computational chemistry ; Geometry ; Composite material ; Chemistry ; Microstructure Graphene research and applications ; 2D Materials and Applications ; Topological Materials and Phenomena
Authors: Ryan Katona | Demitri Maestas | Matthew Roop | Rebecca Schaller | Mark P. Wilson | David Montes de Oca Zapiain | Michael Melia | Philip Noell
Source:  (article, 2023-07-01)
Field: Materials Science — Materials Chemistry

Modeling the Stochastic Nature of Corrosion Reactions in Atmospheric Conditions Corrosion ; Atmospheric model ; Environmental science ; Computer science ; Materials science ; Meteorology ; Metallurgy ; Physics Material Properties and Failure Mechanisms