jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Stanislav S. Borysov | Bart Olsthoorn | M. Berk Gedik | R. Matthias Geilhufe | Alexander V. Balatsky
Source: npj Computational Materials (article, 2018-08-14)
Field: Materials Science — Materials Chemistry

Online search tool for graphical patterns in electronic band structures Abstract Many functional materials can be characterized by a specific pattern in their electronic band structure, for example, Dirac materials, characterized by a linear crossing of bands; topological insulators, characterized by a “Mexican hat” pattern or an effectively free electron gas, characterized by a parabolic dispersion. To find material realizations of these features, manual inspection of electronic band structures represents a relatively easy task for a small number of materials. However, the growing amount of data contained within modern electronic band structure databases makes this approach impracticable. To address this problem, we present an automatic graphical pattern search tool implemented for the electronic band structures contained within the Organic Materials Database. The tool is capable of finding user-specified graphical patterns in the collection of thousands of band structures from high-throughput calculations in the online regime. Using this tool, it only takes a few seconds to find an arbitrary graphical pattern within the ten electronic bands near the Fermi level for 26,739 organic crystals. The source code of the developed tool is freely available and can be adapted to any other electronic band structure database. Task (project management) ; Electronic band ; Electronic band structure ; Electronic structure ; Fermi Gamma-ray Space Telescope ; Code (set theory) Machine Learning in Materials Science ; Topological Materials and Phenomena ; Topological and Geometric Data Analysis
Authors: Tomasz Majchrzak | W. Wojnowski | Tomasz Dymerski | Jacek Gębicki | Jacek Namieśnik
Source: Food Analytical Methods (article, 2018-07-07)
Field: Chemistry — Organic Chemistry

Complementary Use of Multi-dimensional Gas Chromatography and Proton Transfer Reaction Mass Spectrometry for Identification of Rapeseed Oil Quality Indicators The change of concentration of various volatiles generated during frying may be an indicator of oil quality. Chemical compounds such as aldehydes, ketones, alcohols and carboxyl acids are the products of oxidation during thermal degradation of edible oils. Shown in this work is a complementary use of GC×GC-TOFMS and PTR-MS for the detection and determination of quality indicators of rapeseed oil. The former technique was used for the identification of potential markers and the latter for their quantitative determination. As a result of the GC×GC analysis, it was determined that 2-pentanone, heptane, octane, 1-heptanol and nonanal can be considered indicators of thermal degradation of rapeseed oil. Using PTR-MS, it was possible to monitor the concentration of these volatile indicators in real time. Based on the results of the analysis and of the reference method, it was concluded that 1-heptanol is best suited for the role of a quality indicator of thermal degradation of rapeseed oil. Rapeseed ; Nonanal ; Chemistry ; Chromatography ; Mass spectrometry ; Gas chromatography ; Gas chromatography–mass spectrometry ; Degradation (telecommunications) ; Food science ; Computer science Edible Oils Quality and Analysis ; Advanced Chemical Sensor Technologies ; Spectroscopy and Chemometric Analyses
Authors: Shiu Fai Frankie Li
Source: Research Showcase @ Carnegie Mellon University (Carnegie Mellon University) (article, 2018-01-01)
Field: Materials Science — Materials Chemistry

Imaging of Orientation and Geometry in Microstructures: Development and Applications of High Energy X-ray Diffraction Microscopy Near-field High Energy X-ray Diffraction Microscopy (HEDM) is a synchrotron based imaging technique capable of resolving crystallographic orientation in a bulk, polycrystalline material non-destructively. Recent advances in data acquisition and analysis methods have led to micron-scale spatial resolution and ≤ 0.1º angular resolution of the measured volumetric orientation maps across millimeter sized samples. This is a significant improvement over the previous generation of three-dimensional X-ray techniques, which provides us with the access of statistically significant microstructure volumes. Combined with the use of state-of-the-art surface mesh generation algorithms, this markedly improved resolution results in the capability to directly measure geometrical evolution, such as grain boundary motion, and material deformation in the form of lattice rotations. In this thesis, the algorithms and analysis methods recently developed for HEDM are discussed. This includes the descriptions of the robust geometrical extraction methods used for microstructure feature characterization. A set of validation tests for the Forward Modeling Method and the newly developed orientation reconstruction algorithm, the Stratified Monte Carlo Pruning method, is also detailed. By using HEDM to measure the annealing of high purity nickel, grain boundary motion for different boundary types are measured and presented. Moreover, the use of HEDM enabled us to observe the first ever spatially resolved lattice rotation in a high purity copper wire under uni-axial tension, thus demonstrating HEDM’s applicability to defected materials. Orientation (vector space) ; Geometry ; Microscopy ; Materials science ; Diffraction ; X-ray ; Optics ; Development (topology) ; X-ray crystallography ; Crystallography ; Physics ; Chemistry ; Mathematics ; Mathematical analysis X-ray Diffraction in Crystallography ; Advanced X-ray Imaging Techniques
Authors: Xiaodan Hong | Biao Huang | Yongsheng Ding | Fan Guo | Lei Chen | Lihong Ren
Source: Transactions of the Institute of Measurement and Control (article, 2018-11-21)
Field: Chemistry — Analytical Chemistry

Multivariate Gaussian process regression for nonlinear modelling with colored noise Nonlinearity of process systems along with colored noises is common in chemical processes. A multivariate (multiple inputs and multiple outputs) Gaussian process regression (MGPR) modelling approach, which can model multivariate nonlinear processes, is developed in this paper. The developed GPR model considers the Gaussian colored noise, rather than the traditional Gaussian white noise. The colored noise is described by the moving average (MA) model and the autoregressive (AR) model, respectively, with unknown parameters so that a MA-GPR model and an AR-GPR model are developed. These two colored noise based models are further extended to the MGPR model to generate the MA-MGPR model and the AR-MGPR model. The covariance functions of the MA-MGPR model or the AR-MGPR model are formulated with consideration of the autocorrelation of noises. Moreover, all parameters are estimated by using a unidimensional updated particle swarm optimization (PSO) algorithm, simultaneously. Numerical examples as well as a three-level drawing model of Carbon fiber production process are used to demonstrate the effectiveness of the proposed modelling approaches. Autoregressive model ; Colors of noise ; White noise ; Gaussian process ; Noise (video) ; Autocorrelation ; Multivariate statistics ; Colored ; Kriging ; Gaussian noise ; Covariance ; Nonlinear system ; Computer science ; Mathematics ; Gaussian ; Algorithm ; Artificial intelligence ; Statistics ; Physics Spectroscopy and Chemometric Analyses ; Fault Detection and Control Systems ; Mineral Processing and Grinding
Authors: Liu Chu | Jiajia Shi | Eduardo Souza de Cursi | Xunqian Xu | Yazhou Qin | Hongliang Xiang
Source: Journal of Nanomaterials (article, 2018-10-10)
Field: Materials Science — Materials Chemistry

Monte Carlo-Based Finite Element Method for the Study of Randomly Distributed Vacancy Defects in Graphene Sheets This paper proposed an effective stochastic finite element method for the study of randomly distributed vacancy defects in graphene sheets. The honeycomb lattice of graphene is represented by beam finite elements. The simulation results of the pristine graphene are in accordance with literatures. The randomly dispersed vacancies are propagated and performed in graphene by integrating Monte Carlo simulation (MCS) with the beam finite element model (FEM). The results present that the natural frequencies of different vibration modes decrease with the augment of the vacancy defect amount. When the vacancy defect reaches 5%, the regularity and geometrical symmetry of displacement and rotation in vibration behavior are obviously damaged. In addition, with the raise of vacancy defects, the random dispersion position of vacancy defects increases the variance in natural frequencies. The probability density distributions of natural frequencies are close to the Gaussian and Weibull distributions. Vacancy defect ; Materials science ; Finite element method ; Graphene ; Monte Carlo method ; Vibration ; Lattice (music) ; Condensed matter physics ; Structural engineering ; Physics ; Nanotechnology ; Mathematics ; Statistics ; Quantum mechanics Graphene research and applications ; Probabilistic and Robust Engineering Design ; Graphite, nuclear technology, radiation studies
Authors: Cristian Balbuena | Melisa M. Gianetti | Ezequiel R. Soulé
Source: The Journal of Chemical Physics (article, 2018-09-07)
Field: Materials Science — Materials Chemistry

Looking at the dynamical heterogeneity in a supercooled polymer system through isoconfigurational ensemble The dynamic correlations that emerge in a polymer system in supercooling conditions have been studied using molecular dynamic simulations. It is known that when a glass former approaches the glass transition temperature, the dynamics of the system (in terms of the mobilities of the particles) not only significantly slows down but also becomes more heterogeneous. Several theories relate this slowing down to increasing spatial (structural) correlations, for example, through the onset of cooperative relaxation regions in the Adam-Gibbs theory. In this work, we employ Pearson's coefficient in the isoconfigurational ensemble (ICE) which allows us to study the dynamic correlations of the monomers in the ICE and establish the relation between the structure of the monomers and its dynamic behavior. Similar to what happens with mobility, monomers with highest correlation are clustered, and the clustering increases with decreasing temperature. An interesting result is that regions with high ICE dynamic correlation are not coincident with highly mobile or immobile regions. These results represent a new approach to the study of dynamic heterogeneity that emerges in glass forming liquids, complementing the more traditional characterization in terms of mobility. The methodology proposed in this work that characterize the connected dynamic regions to structural causes can represent an alternative way to observe the cooperative relaxation regions. Supercooling ; Glass transition ; Statistical physics ; Dynamical heterogeneity ; Relaxation (psychology) ; Work (physics) ; Molecular dynamics ; Thermodynamics ; Monomer ; Characterization (materials science) ; Polymer ; Materials science ; Chemical physics ; Physics ; Chemistry ; Nanotechnology ; Computational chemistry Material Dynamics and Properties ; Phase Equilibria and Thermodynamics ; Rheology and Fluid Dynamics Studies
Authors: Yair Litman | Hernán B. Rodríguez | Silvia E. Braslavsky | Enrique San Román
Source: Photochemistry and Photobiology (article, 2018-07-07)
Field: Chemistry — Physical and Theoretical Chemistry

Photophysics of Xanthene Dyes at High Concentrations in Solid Environments: Charge Transfer Assisted Triplet Formation The photophysical behavior of two xanthene dyes, Eosin Y and Phloxine B, included in microcrystalline cellulose particles is studied in a wide concentration range, with emphasis on the effect of dye concentration on fluorescence and triplet quantum yields. Absolute fluorescence quantum yields in the solid-state were determined by means of diffuse reflectance and steady-state fluorescence measurements, whereas absolute triplet quantum yields were obtained by laser-induced optoacoustic spectroscopy and their dependence on dye concentration was confirmed by diffuse reflectance laser flash photolysis and time-resolved phosphorescence measurements. When both quantum yields are corrected for reabsorption and reemission of radiation, Φ<sub>F</sub> values decrease strongly on increasing dye concentration, while a less pronounced decay is observed for Φ<sub>T</sub> . Fluorescence concentration quenching is attributed to the formation of dye aggregates or virtual traps resulting from molecular crowding. Dimeric traps are however able to generate triplet states. A mechanism based on the intermediacy of charge-transfer states is proposed and discussed. Calculation of parameters for photoinduced electron transfer between dye molecules within the traps evidences the feasibility of the proposed mechanism. Results demonstrate that photoactive energy traps, capable of yielding dye triplet states, can be formed even in highly-concentrated systems with random dye distributions. Xanthene ; Photochemistry ; Chemistry ; Phosphorescence ; Fluorescence ; Triplet state ; Flash photolysis ; Dye laser ; Intersystem crossing ; Quenching (fluorescence) ; Excited state ; Analytical Chemistry (journal) ; Molecule ; Singlet state ; Laser ; Optics ; Atomic physics ; Kinetics ; Organic chemistry Photochemistry and Electron Transfer Studies ; Porphyrin and Phthalocyanine Chemistry ; Luminescence and Fluorescent Materials
Authors: Hector Lopez-Rios | Jose-L. Mendoza-Cortes | Serguei Fomine | Pablo Pedro, Ricardo | Jing Kong | Troy Van Voorhis | M. S. Dresselhaus
Source: DSpace@MIT (Massachusetts Institute of Technology) (article, 2018-02-01)
Field: Materials Science — Materials Chemistry

Exploring Low Internal Reorganization Energies for Silicene Nanoclusters This paper is a contribution to the Physical Review Applied collection in memory of Mildred S. Dresselhaus. High-performance materials rely on small reorganization energies to facilitate both charge separation and charge transport. Here, we perform density-functional-theory calculations to predict small reorganization energies of rectangular silicene nanoclusters with hydrogen-passivated edges denoted by H-SiNC. We observe that across all geometries, H-SiNCs feature large electron affinities and highly stabilized anionic states, indicating their potential as n-type materials. Our findings suggest that fine-tuning the size of H-SiNCs along the “zigzag” and “armchair” directions may permit the design of novel n-type electronic materials and spintronics devices that incorporate both high electron affinities and very low internal reorganization energies. Nanoclusters ; Silicene ; Materials science ; Chemical physics ; Nanotechnology ; Physics ; Graphene Graphene research and applications ; 2D Materials and Applications ; Carbon and Quantum Dots Applications
Authors: M. Barletta | Clizia Aversa | Elisa Pizzi | M. Puopolo | Silvia Vesco
Source: Polymer Engineering and Science (article, 2018-10-17)
Field: Materials Science — Biomaterials

Engineered poly(lactic acid)‐talc biocomposites for melt processing: Effects of co‐blending with poly(butylene succinate) and poly(butylene terephthalate) on thermal and mechanical behavior This article deals with the design and manufacturing of a novel class of PLA‐based material specifically engineered for injection molding, suitable for food contact and characterized by a good balance of mechanical properties and thermal resistance. A commercial PLA grade was modified by blending it with microlamellar talc as reinforcing filler, poly(butylene succinate) (PBS), and poly(butylene terephthalate) (PBT) as secondary polymeric phases. Ternary blend/talc biocomposites were achieved. The different constituents of the biocomposites were compatibilized by reactive compounding extrusion using maleic anhydride (MAH) grafted PLA (PLA‐MA). The thermal properties of the compounds prior and after injection molding were characterized by differential scanning calorimetry. The mechanical response of the injection molded materials was evaluated by flat indentation and flexural tests. The mechanical properties of the PLA/talc‐based biocomposites and crystallinity of PLA can be controlled by fine tuning the blend by the addition of PBS and PBT in the formulation. In particular, biocomposites characterized by good strength and toughness can be obtained by injection molding, without affecting thermal stability. Based on the experimental findings, the PLA‐based formulations pose; therefore, solid bases for replacing oil‐based plastics in several markets, specifically in the segment of food and pharmaceutical packaging. POLYM. ENG. SCI., 59:264–273, 2019. © 2018 Society of Plastics Engineers Materials science ; Talc ; Composite material ; Polybutylene succinate ; Compounding ; Molding (decorative) ; Extrusion ; Injection moulding ; Differential scanning calorimetry ; Maleic anhydride ; Thermal stability ; Crystallinity ; Polymer ; Chemical engineering ; Copolymer biodegradable polymer synthesis and properties ; Additive Manufacturing and 3D Printing Technologies ; Carbon dioxide utilization in catalysis
Authors: Yong Yu | Preston Yi Jie Ching | Yen Nee Tan
Source: Advanced Materials Letters (article, 2018-07-26)
Field: Materials Science — Materials Chemistry

Microwave-assisted synthesis and mechanistic study of multicolor emissive Au nanoclusters using thiol-containing biomolecules Developing effective synthesis method for few-atom gold nanoclusters (AuNCs) with tunable emissions is vitally important to gain better understanding of their formation mechanism and provide more design flexibilities to suite for various applications such as multiplex cellular imaging and/or light-emitting diodes. This paper reports a fast method (<30 minutes) of preparing multicolour (red, orange, near infrared) emissive AuNCs via a microwave-assisted biotemplating synthesis approach. A series of analytical tools such as UV-vis and photoluminescence spectroscopies, transmission electron microscopy (TEM) and polyacrylamide gel electrophoresis (PAGE) have been utilized to characterize the resultant AuNCs and unravel the formation mechanism that lead to their multicolour emissive properties. It was found that the surface charge of the thiol-containing peptide reagent and the peptide-to-Au ratio are crucial factors to control the size and emission colour of the resultant AuNCs. By bringing the solution pH to near the isoelectric point of peptide ligand (~3), the red (lem = 725 nm) emissive AuNC which is initially stable at alkaline conditions (pH-12) tends to aggregate due to deficiency of surface charge, thus forming a larger and orange (lem = 640 nm) emissive AuNC. By further applying an even lower peptide-to-Au ratio to fine-tune the protection power of thiolate ligands, a near-infrared (lem = 846 nm) emissive AuNC has been synthesized. Compared to other microwave-assisted synthesis of AuNCs, current study is featured by its simplicity, rapidity, and versatility to tune the emission wavelength of resultant AuNCs in a much broader range (up to 206 nm). Nanoclusters ; Materials science ; Photoluminescence ; Biomolecule ; Nanomaterials ; Nanotechnology ; Optoelectronics Nanocluster Synthesis and Applications ; Advanced Nanomaterials in Catalysis ; Gold and Silver Nanoparticles Synthesis and Applications
Authors: Sven Warfsmann | Dereje H. Taffa | Michael Wark
Source: Journal of Photochemistry and Photobiology A Chemistry (article, 2018-05-24)
Field: Materials Science — Materials Chemistry

Photoelectrocatalytic behavior of electrodeposited zinc ferrite films with varying Zn:Fe ratio X-ray photoelectron spectroscopy ; Zinc ; Materials science ; Raman spectroscopy ; Amorphous solid ; Stoichiometry ; Photocurrent ; Ferrite (magnet) ; Zinc ferrite ; Triethanolamine ; Analytical Chemistry (journal) ; Transmission electron microscopy ; Inorganic chemistry ; Chemical engineering ; Chemistry ; Metallurgy ; Nanotechnology ; Crystallography Copper-based nanomaterials and applications ; Iron oxide chemistry and applications ; Magnetic Properties and Synthesis of Ferrites
Authors: Florian Strassl | Alexander Hoffmann | Benjamin Grimm‐Lebsanft | Dieter Rukser | Florian Biebl | Mai Anh Tran | Fabian Metz | Michael Rübhausen | Sonja Herres‐Pawlis
Source: Inorganics (article, 2018-10-20)
Field: Chemistry — Inorganic Chemistry

Fluorescent Bis(guanidine) Copper Complexes as Precursors for Hydroxylation Catalysis Bis(guanidine) copper complexes are known for their ability to activate dioxygen. Unfortunately, until now, no bis(guanidine) copper-dioxygen adduct has been able to transfer oxygen to substrates. Using an aromatic backbone, fluorescence properties can be added to the copper(I) complex which renders them useful for later reaction monitoring. The novel bis(guanidine) ligand DMEG2tol stabilizes copper(I) and copper(II) complexes (characterized by single crystal X-ray diffraction, IR spectroscopy, and mass spectrometry) and, after oxygen activation, bis(µ-oxido) dicopper(III) complexes which have been characterized by low-temperature UV/Vis and Raman spectroscopy. These bis(guanidine) stabilized bis(µ-oxido) complexes are able to mediate tyrosinase-like hydroxylation activity as first examples of bis(guanidine) stabilized complexes. The experimental study is accompanied by density functional theory calculations which highlight the special role of the different guanidine donors. Guanidine ; Chemistry ; Copper ; Hydroxylation ; Adduct ; Photochemistry ; Copper protein ; Polymer chemistry ; Combinatorial chemistry ; Organic chemistry Metal-Catalyzed Oxygenation Mechanisms ; Metal complexes synthesis and properties ; Vanadium and Halogenation Chemistry
Authors: А. С. Вашурин | Ilya A. Kuzmin | Mikhail Razumov | О. А. Голубчиков | О. И. Койфман
Source: Macroheterocycles (article, 2018-01-01)
Field: Materials Science — Materials Chemistry

Catalytically Active Systems of Cobalt Complexes with Wa-ter-Soluble Phthalocyanines The work reports catalytic properties of series of cobalt phthalocyanines peripherally substituted with consistently changing sulfonated fragments. Data on heterogenization of cobalt phthalocyaninates onto organic and inorganic polymers are provided. Comparing catalytic activity of the macrocycles in dependence on structure and peripheral substituent as well as polymer carrier's type is given. Application of cobalt phthalocyanine's sulfonic acids for fine synthesis of thiuram E upon both homogeneous and heterogeneous catalysis is shown to be prospective. Cobalt ; Chemistry ; Polymer chemistry ; Organic chemistry Porphyrin and Phthalocyanine Chemistry ; Metal-Catalyzed Oxygenation Mechanisms ; Organic Chemistry Cycloaddition Reactions