jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Yakun Yuan | Yanfu Lu | Greg Stone | Ke Wang | Charles M. Brooks | Darrell G. Schlom | Susan B. Sinnott | Hua Zhou | Venkatraman Gopalan
Source: Nature Communications (article, 2018-11-30)
Field: Materials Science — Materials Chemistry

Three-dimensional atomic scale electron density reconstruction of octahedral tilt epitaxy in functional perovskites Octahedral tilts are the most ubiquitous distortions in perovskite-related structures that can dramatically influence ferroelectric, magnetic, and electronic properties; yet the paradigm of tilt epitaxy in thin films is barely explored. Non-destructively characterizing such epitaxy in three-dimensions for low symmetry complex tilt systems composed of light anions is a formidable challenge. Here we demonstrate that the interfacial tilt epitaxy can transform ultrathin calcium titanate, a non-polar earth-abundant mineral, into high-temperature polar oxides that last above 900 K. The comprehensive picture of octahedral tilts and polar distortions is revealed by reconstructing the three-dimensional electron density maps across film-substrate interfaces with atomic resolution using coherent Bragg rod analysis. The results are complemented with aberration-corrected transmission electron microscopy, film superstructure reflections, and are in excellent agreement with density functional theory. The study could serve as a broader template for non-destructive, three-dimensional atomic resolution probing of complex low symmetry functional interfaces. Tilt (camera) ; Atomic units ; High-resolution transmission electron microscopy ; Materials science ; Perovskite (structure) ; Epitaxy ; Density functional theory ; Superstructure ; Polar ; Substrate (aquarium) ; Ferroelectricity ; Octahedron ; Transmission electron microscopy ; Thin film ; Condensed matter physics ; Crystallographic point group ; Scanning transmission electron microscopy ; Chemical physics ; Crystallography ; Nanotechnology ; Optoelectronics ; Chemistry ; Crystal structure ; Physics ; Computational chemistry ; Geology ; Geometry ; Dielectric Electronic and Structural Properties of Oxides ; Magnetic and transport properties of perovskites and related materials ; Ferroelectric and Piezoelectric Materials
Authors: Daomin Min | Chenyu Yan | Rui Mi | Chao Ma | Yin Huang | Shengtao Li | Qingzhou Wu | Zhaoliang Xing
Source: Polymers (article, 2018-10-30)
Field: Materials Science — Materials Chemistry

Carrier Transport and Molecular Displacement Modulated dc Electrical Breakdown of Polypropylene Nanocomposites Dielectric energy storage capacitors have advantages such as ultra-high power density, extremely fast charge and discharge speed, long service lifespan and are significant for pulsed power system, smart power grid, and power electronics. Polypropylene (PP) is one of the most widely used dielectric materials for dielectric energy storage capacitors. It is of interest to investigate how to improve its electrical breakdown strength by nanodoping and the influencing mechanism of nanodoping on the electrical breakdown properties of polymer nanocomposites. PP/Al₂O₃ nanocomposite dielectric materials with various weight fraction of nanoparticles are fabricated by melt-blending and hot-pressing methods. Thermally stimulated current, surface potential decay, and dc electrical breakdown experiments show that deep trap properties and associated molecular chain motion are changed by incorporating nanofillers into polymer matrix, resulting in the variations in conductivity and dc electrical breakdown field of nanocomposite dielectrics. Then, a charge transport and molecular displacement modulated electrical breakdown model is utilized to simulate the dc electrical breakdown behavior. It is found that isolated interfacial regions formed in nanocomposite dielectrics at relatively low loadings reduce the effective carrier mobility and strengthen the interaction between molecular chains, hindering the transport of charges and the displacement of molecular chains with occupied deep traps. Accordingly, the electrical breakdown strength is enhanced at relatively low loadings. Interfacial regions may overlap in nanocomposite dielectrics at relatively high loadings so that the effective carrier mobility decreases and the interaction between molecular chains may be weakened. Consequently, the molecular motion is accelerated by electric force, leading to the decrease in electrical breakdown strength. The experiments and simulations reveals that the influence of nanodoping on dc electrical breakdown properties may origin from the changes in the charge transport and molecular displacement characteristics caused by interfacial regions in nanocomposite dielectrics. Polypropylene ; Materials science ; Nanocomposite ; Composite material ; Displacement (psychology) High voltage insulation and dielectric phenomena ; Dielectric materials and actuators ; Electrostatic Discharge in Electronics
Authors: Ivan S. Novikov | Yury V. Suleimanov | Alexander V. Shapeev
Source: Physical Chemistry Chemical Physics (article, 2018-01-01)
Field: Materials Science — Materials Chemistry

Automated calculation of thermal rate coefficients using ring polymer molecular dynamics and machine-learning interatomic potentials with active learning We propose a methodology for the fully automated calculation of thermal rate coefficients of gas phase chemical reactions, which is based on combining ring polymer molecular dynamics (RPMD) and machine-learning interatomic potentials actively learning on-the-fly. Based on the original computational procedure implemented in the RPMDrate code, our methodology gradually and automatically constructs the potential energy surfaces (PESs) from scratch with the data set points being selected and accumulated during the RPMDrate simulation. Such an approach ensures that our final machine-learning model provides a reliable description of the PES that avoids artifacts during exploration of the phase space by RPMD trajectories. We tested our methodology on two representative thermally activated chemical reactions studied recently by RPMDrate at temperatures within the interval of 300-1000 K. The corresponding PESs were generated by fitting to only a few thousand automatically generated structures (less than 5000) while the RPMD rate coefficients showed deviation from the reference values within the typical convergence error of RPMDrate. In future, we plan to apply our methodology to chemical reactions that proceed via complex-formation thus providing a completely general tool for calculating RPMD thermal rate coefficients for any polyatomic gas phase chemical reaction. Molecular dynamics ; Computer science ; Interatomic potential ; Interval (graph theory) ; Phase space ; Convergence (economics) ; Thermal ; Polyatomic ion ; Potential energy ; Algorithm ; Simulation ; Thermodynamics ; Chemistry ; Computational chemistry ; Mathematics ; Physics ; Atomic physics ; Molecule ; Quantum mechanics Machine Learning in Materials Science ; Computational Drug Discovery Methods ; Nuclear Materials and Properties
Authors: Kehang Han | Adeel Jamal | Colin A. Grambow | Zachary J. Buras | William H. Green
Source: International Journal of Chemical Kinetics (article, 2018-02-08)
Field: Chemistry — Organic Chemistry

An Extended Group Additivity Method for Polycyclic Thermochemistry Estimation ABSTRACT Automatic kinetic mechanism generation, virtual high‐throughput screening, and automatic transition state search are currently trending applications requiring exploration of a large molecule space. Large‐scale search requires fast and accurate estimation of molecules' properties of interest, such as thermochemistry. Existing approaches are not satisfactory for large polycyclic molecules: considering the number of molecules being screened, quantum chemistry (even cheap density functional theory methods) can be computationally expensive, and group additivity, though fast, is not sufficiently accurate. This paper provides a fast and moderately accurate alternative by proposing a polycyclic thermochemistry estimation method that extends the group additivity method with two additional algorithms: similarity match and bicyclic decomposition. It significantly reduces H f (298 K) estimation error from over 60 kcal/mol (group additivity method) to around 5 kcal/mol, C p (298 K) error from 9 to 1 cal/mol/K, and S (298 K) error from 70 to 7 cal/mol/K. This method also works well for heteroatomic polycyclics. A web application for estimating thermochemistry by this method is made available at http://rmg.mit.edu/molecule_search . Thermochemistry ; Additive function ; Chemistry ; Molecule ; Group (periodic table) ; Computational chemistry ; Decomposition ; Quantum chemistry ; Density functional theory ; Thermodynamics ; Physical chemistry ; Mathematics ; Organic chemistry ; Physics Chemical Thermodynamics and Molecular Structure ; Computational Drug Discovery Methods ; Machine Learning in Materials Science
Authors: Tianyu Zhang | Jiawen Kang | Dezhuang Meng | Hongwei Wang | Zhengming Mu | Meng Zhou | Xiaotong Zhang | Chen Chen
Source: Sensors (review, 2018-12-06)
Field: Chemistry — Spectroscopy

Mathematical Methods and Algorithms for Improving Near-Infrared Tunable Diode-Laser Absorption Spectroscopy Tunable diode laser absorption spectroscopy technology (TDLAS) has been widely applied in gaseous component analysis based on gas molecular absorption spectroscopy. When dealing with molecular absorption signals, the desired signal is usually interfered by various noises from electronic components and optical paths. This paper introduces TDLAS-specific signal processing issues and summarizes effective algorithms so solve these. Tunable diode laser absorption spectroscopy ; Absorption (acoustics) ; Spectroscopy ; Diode ; Absorption spectroscopy ; Laser ; SIGNAL (programming language) ; Infrared spectroscopy ; Signal processing ; Tunable laser ; Materials science ; Infrared ; Optoelectronics ; Optics ; Computer science ; Chemistry ; Physics ; Digital signal processing ; Computer hardware Spectroscopy and Laser Applications ; Water Quality Monitoring and Analysis ; Advanced Chemical Sensor Technologies
Authors: Yang Zhou | Guori Zhang | Haiyan Chen | Peiheng Zhou | Xin Wang | Linbo Zhang | Li Zhang | Jianliang Xie | Longjiang Deng
Source: Scientific Reports (article, 2018-05-31)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Design of Phase Gradient Coding Metasurfaces for Broadband Wave Modulating Wave modulating is one of the most interesting applications of metasurfaces. It requires an effective method to design metasurfaces with arbitrary space-variant phase. In this paper, we proposed an optimized design method for arbitrarily modulating wave based on the Genetic Algorithm, which is efficient to optimize designated radiation patterns according to application requirements. In order to verify the availability of the method, wave modulating of single lobe radiation at 10 GHz and broadband 3-lobes radiation at X band are optimized. For wave modulating of single lobe radiation, eight basic codes are chosen to excite the specific phases evenly dispersed from 0 to 2π for smooth phase gradient, and the 8 × 8, 20 × 20 and 40 × 40 arrays of the basic codes are optimized. It proves that the wave modulation accuracy is enhancing with the increase of elements quantity. For wave modulating of 3-lobes radiation, the 20 × 20 arrays are proposed and optimized, and their basic codes are increased to 32 for meeting the broadband requirement. Its broadband wave modulating has been verified by simulation and experiment, and it is shown that the directional 3-lobes radiation patterns keeps nearly stable within the broadband frequency range of 8.7-11.3 GHz. Broadband ; Coding (social sciences) ; Computer science ; Phase (matter) ; Phase response ; Telecommunications ; Optics ; Physics ; Mathematics Metamaterials and Metasurfaces Applications ; Advanced Antenna and Metasurface Technologies ; Antenna Design and Analysis
Authors: Cecilia A. Zito | Marcelo O. Orlandi | Diogo P. Volanti
Source: Journal of Electroceramics (article, 2018-03-12)
Field: Chemistry — Organic Chemistry

Accelerated microwave-assisted hydrothermal/solvothermal processing: Fundamentals, morphologies, and applications Materials science ; Nanotechnology ; Ostwald ripening ; Hydrothermal circulation ; Graphene ; Microwave ; Solvothermal synthesis ; Chemical engineering ; Computer science ; Telecommunications Microwave-Assisted Synthesis and Applications ; Nanomaterials for catalytic reactions ; MXene and MAX Phase Materials
Authors: Biao Chen | Xuepeng Zhang | Yucai Wang | Hui Miao | Guoqing Zhang
Source: Chemistry - An Asian Journal (article, 2018-07-19)
Field: Materials Science — Materials Chemistry

Aggregation‐Induced Emission with Long‐Lived Room‐Temperature Phosphorescence from Methylene‐Linked Organic Donor–Acceptor Structures Aggregation-caused quenching (ACQ), where excited-state and/or ground-state electronic structures are altered to exhibit an increased proclivity for non-radiative decay for the aggregates, is largely responsible for the lack of fluorescence and phosphorescence in molecular solids in general. Here we show that ACQ could be effectively circumvented by constructing an aromatic system with a methylene-linker, where the system exhibits typical aggregation-induced emission (AIE) with long-lived room-temperature phosphorescence, since the tetrahedral structure in the solid state may significantly reduce strong intermolecular interactions contributing to ACQ. Phosphorescence ; Acceptor ; Photochemistry ; Methylene ; Methylene blue ; Chemistry ; Materials science ; Fluorescence ; Catalysis ; Organic chemistry ; Optics ; Physics Luminescence and Fluorescent Materials ; Molecular Sensors and Ion Detection ; Organic Light-Emitting Diodes Research
Authors: Bowen Ding | Carol Hua | Cameron J. Kepert | Deanna M. D’Alessandro
Source: Chemical Science (article, 2018-10-29)
Field: Chemistry — Inorganic Chemistry

Influence of structure–activity relationships on through-space intervalence charge transfer in metal–organic frameworks with cofacial redox-active units Understanding charge transfer in redox-active metal-organic frameworks (MOFs) is of fundamental importance given the potential of these materials to be used in myriad applications including porous conductors, electrocatalysts and battery materials, amongst others. An important challenge is quantifying the spectroscopic features of these materials in order to elucidate their charge transfer properties. Herein, two topologically related Zn(ii) and Cd(ii) frameworks, [Zn<sub>2</sub>(DPPTzTz)<sub>2</sub>(SDC)<sub>2</sub>] (<b>1-Zn</b>) and [Cd<sub>2</sub>(DPPTzTz)<sub>2</sub>(SDC)<sub>2</sub>] (<b>2-Cd</b>) (where DPPTzTz = 2,5-bis(4-(4-pyridinyl)phenyl)thiazolo[5,4-<i>d</i>]thiazole and SDC = selenophene-2,5-dicarboxylate), incorporating cofacially stacked pairs of redox-active DPPTzTz ligands are presented. The differences in the through-space intervalence charge transfer properties of the mixed-valence forms of the two frameworks generated upon solid state spectroelectrochemical reduction are quantified using Marcus-Hush theory. Further, charge transfer theory is applied to calculate electron mobilities in both extended framework systems. A larger electronic coupling constant, <i>H</i> <sub>ab</sub>, of 118 cm<sup>-1</sup> corresponding to an electron mobility, <i>k</i>, of 6.02 × 10<sup>8</sup> s<sup>-1</sup> was observed for the Zn(ii) analogue compared to the Cd(ii) analogue (<i>H</i> <sub>ab</sub> = 61.2 cm<sup>-1</sup> and <i>k</i> = 2.22 × 10<sup>8</sup> s<sup>-1</sup>) and was correlated primarily with the larger cofacial stacking distance and increasingly offset stacking geometry between DPPTzTz ligands in the latter. Establishing structure-activity relationships in electroactive MOFs, in addition to methods for quantifying their charge transfer properties, represents an important advance in fine tuning solid state materials for device applications. Redox ; Metal ; Space (punctuation) ; Charge (physics) ; Transfer (computing) ; Chemistry ; Photochemistry ; Materials science ; Inorganic chemistry ; Physics ; Computer science ; Organic chemistry ; Quantum mechanics Metal-Organic Frameworks: Synthesis and Applications ; Crystallography and molecular interactions ; Organic and Molecular Conductors Research
Authors: Simon H. Tran | Clive Wilson | F. Philipp Seib
Source: Pharmaceutical Research (review, 2018-11-05)
Field: Materials Science — Biomaterials

A Review of the Emerging Role of Silk for the Treatment of the Eye Silk is a remarkable biopolymer with a long history of medical use. Silk fabrications have a robust track record for load-bearing applications, including surgical threads and meshes, which are clinically approved for use in humans. The progression of top-down and bottom-up engineering approaches using silk as the basis of a drug delivery or cell-loaded matrix helped to re-ignite interest in this ancient material. This review comprehensively summarises the current applications of silk for tissue engineering and drug delivery, with specific reference to the eye. Additionally, the review also covers emerging trends for the use of silk as a biologically active biopolymer for the treatment of eye disorders. The review concludes with future capabilities of silk to contribute to advanced, electronically-enhanced ocular drug delivery concepts. SILK ; Drug delivery ; Biopolymer ; Tissue engineering ; Nanotechnology ; Medicine ; Biomedical engineering ; Computer science ; Materials science Silk-based biomaterials and applications ; Biochemical and Structural Characterization ; Protease and Inhibitor Mechanisms
Authors: Vishwesh Venkatraman | Bjørn K. Alsberg
Source: Polymers (article, 2018-01-22)
Field: Materials Science — Materials Chemistry

Designing High-Refractive Index Polymers Using Materials Informatics A machine learning strategy is presented for the rapid discovery of new polymeric materials satisfying multiple desirable properties. Of particular interest is the design of high refractive index polymers. Our in silico approach employs a series of quantitative structure⁻property relationship models that facilitate rapid virtual screening of polymers based on relevant properties such as the refractive index, glass transition and thermal decomposition temperatures, and solubility in standard solvents. Exploration of the chemical space is carried out using an evolutionary algorithm that assembles synthetically tractable monomers from a database of existing fragments. Selected monomer structures that were further evaluated using density functional theory calculations agree well with model predictions. Polymer ; Refractive index ; Monomer ; Glass transition ; Materials science ; Computer science ; Decomposition ; Biological system ; Chemistry ; Organic chemistry ; Optoelectronics Machine Learning in Materials Science ; Computational Drug Discovery Methods ; Catalysis and Oxidation Reactions
Authors: Søren Ager Meldgaard | Esben L. Kolsbjerg | Bjørk Hammer
Source: The Journal of Chemical Physics (article, 2018-10-02)
Field: Materials Science — Materials Chemistry

Machine learning enhanced global optimization by clustering local environments to enable bundled atomic energies We show how to speed up global optimization of molecular structures using machine learning methods. To represent the molecular structures, we introduce the <i>auto-bag</i> feature vector that combines (i) a local feature vector for each atom, (ii) an unsupervised clustering of such feature vectors for many atoms across several structures, and (iii) a count for a given structure of how many times each cluster is represented. During subsequent global optimization searches, accumulated structure-energy relations of relaxed structural candidates are used to assign local energies to each atom using supervised learning. Specifically, the local energies follow from assigning energies to each cluster of local feature vectors and demanding the sum of local energies to amount to the structural energies in the least squares sense. The usefulness of the method is demonstrated in basin hopping searches for 19-atom structures described by single- or double-well Lennard-Jones type potentials and for 24-atom carbon structures described by density functional theory. In all cases, utilizing the local energy information derived on-the-fly enhances the rate at which the global minimum energy structure is found. Cluster analysis ; Atom (system on chip) ; Cluster (spacecraft) ; Feature (linguistics) ; Global optimization ; Computer science ; Artificial intelligence ; Energy (signal processing) ; Feature vector ; Pattern recognition (psychology) ; Physics ; Algorithm ; Quantum mechanics Machine Learning in Materials Science ; Computational Drug Discovery Methods ; Crystallography and molecular interactions
Authors: Daniela Florentina Enache | Eugenia Tanasă | Claudia Maria Simonescu | Daniela C. Culiţă | Eugeniu Vasile | Ovidiu Oprea | Andreea Mădălina Pandele | Anca Răzvan | Florina Dumitru | Gheorghe Nechifor
Source: RSC Advances (article, 2018-01-01)
Field: Materials Science — Materials Chemistry

Schiff base-functionalized mesoporous silicas (MCM-41, HMS) as Pb(<scp>ii</scp>) adsorbents MCM-41@salen, HMS-C12@salen and HMS-C16@salen sorbents present high sorption capacities for Pb(<sc>ii</sc>) and are suitable materials for the removal of Pb(<sc>ii</sc>). Mesoporous material ; Sorption ; Adsorption ; Chemistry ; MCM-41 ; Schiff base ; Nuclear chemistry ; Polymer chemistry ; Organic chemistry ; Catalysis Mesoporous Materials and Catalysis ; Adsorption and biosorption for pollutant removal ; Zeolite Catalysis and Synthesis
Authors: Guangya Xu | Bin Li | Ting Wang | Jun Wan | Yan Zhang | Jingwei Huang | Yangmei Shen
Source: RSC Advances (article, 2018-01-01)
Field: Materials Science — Biomaterials

Enhancing the anti-ovarian cancer activity of quercetin using a self-assembling micelle and thermosensitive hydrogel drug delivery system In this study, a quercetin-loaded thermosensitive injectable hydrogel system (Qu-M–hydrogel composites) was constructed based on nanotechnology. Micelle ; Drug delivery ; Quercetin ; Ovarian cancer ; Drug ; Self-healing hydrogels ; Chemistry ; Nanotechnology ; Pharmacology ; Biomedical engineering ; Cancer ; Materials science ; Medicine ; Internal medicine ; Biochemistry ; Polymer chemistry ; Organic chemistry ; Aqueous solution Nanoparticle-Based Drug Delivery ; Nanoplatforms for cancer theranostics ; Supramolecular Self-Assembly in Materials