jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Volker L. Deringer | Noam Bernstein | Gábor Cśanyi | Mark Wilson | D. A. Drabold | Stephen R. Elliott
Source: arXiv (Cornell University) (preprint, 2019-12-16)
Field: Materials Science — Materials Chemistry

Structural transitions in dense disordered silicon from quantum-accurate ultra-large-scale simulations Structurally disordered materials continue to pose fundamental questions, including that of how different disordered phases ("polyamorphs") can coexist and transform from one to another. As a widely studied case, amorphous silicon (a-Si) forms a fourfold-coordinated, covalent random network at ambient conditions, but much higher-coordinated, metallic-like phases under pressure. However, a detailed mechanistic understanding of the liquid-amorphous and amorphous-amorphous transitions in silicon has been lacking, due to intrinsic limitations of even the most advanced experimental and computational techniques. Here, we show how machine-learning (ML)-driven simulations can break through this long-standing barrier, affording a comprehensive, quantum-accurate, and fully atomistic description of all relevant liquid and amorphous phases of silicon. Combining a model system size of 100,000 atoms (ten-nanometre length scale) with a prediction accuracy of a few meV per atom, our simulations reveal a remarkable, three-step transformation sequence for a-Si under increasing external pressure. First, up to 10-11 GPa, polyamorphic low- and high-density amorphous (LDA and HDA) regions are found to coexist, rather than appearing sequentially. Then, we observe a structural collapse into a distinct, very-high-density amorphous (VHDA) phase at 12-13 GPa, reminiscent of the dense liquid but being formed at a much lower temperature. Finally, our simulations indicate the transient nature of this VHDA phase: it rapidly nucleates crystallites at 13-16 GPa, ultimately leading to the formation of a poly-crystalline, simple-hexagonal structure, consistent with experiments but not seen in earlier simulations. Amorphous solid ; Materials science ; Polyamorphism ; Chemical physics ; Atom (system on chip) ; Molecular dynamics ; Silicon ; Crystallite ; Atomic units ; Phase (matter) ; Amorphous silicon ; Length scale ; Nanotechnology ; Crystallography ; Crystalline silicon ; Physics ; Chemistry ; Computational chemistry ; Computer science ; Optoelectronics Machine Learning in Materials Science ; Force Microscopy Techniques and Applications ; Ion-surface interactions and analysis
Authors: Seyed Jafar Sadjadi | Mohammad Reza Naimi‐Jamal
Source: Current Chemistry Letters (article, 2019-01-01)
Field: Chemistry — Inorganic Chemistry

A survey on application of MOFs in chemistry Metal-organic frameworks (MOFs) are combinations of metal ions or clusters accommodated to organic ligands to shape different dimensional structures. MOFs are considered as a subclass of coordination polymers, with the possible characteristics that they are normally porous. The metals are considered to offer flexible, co-ordination environment under virtually various topologies. Besides, because of the usual liability of metal complexes, the shape of the coordination bonds between the metal ions and the organic linkers can be reversible and this helps the rearrangement of metal ions and organic linkers through the process of polymerization to give highly ordered framework structures. The study has indicated that MOFs has maintained extensive applications in Biological imaging and sensing, Drug delivery systems, Methane storage, Semiconductors, Bio-mimetic mineralization, Carbon capture, Desalination/ion separation, Water vapor capture and Ferroelectrics and Multiferroics. This paper presents a scientometrics study on 1273 papers published articles, books, patents, etc. indexed in Web of Science database over the period 2001-2019. The study presents the most popular keywords used in the literature, determines the network of scientific scholars and discusses the clusters of keywords used for different surveys. The results indicate that metalorganic frameworks and zeoitic imidazolate frameworks are two keywords considered as motor keywords in MOFs studies. Chemistry ; Nanotechnology Metal-Organic Frameworks: Synthesis and Applications ; Gas Sensing Nanomaterials and Sensors ; Chemical Synthesis and Reactions
Authors: Nicole Cordonnier
Source: Scholar Commons (University of South Carolina) (article, 2019-01-01)
Field: Materials Science — Materials Chemistry

Flame Spray Pyrolysis of Ce-Mn Solid Solutions for Catalytic Applications Flame spray pyrolysis (FSP) is a method of quickly synthesizing active particles in a flame. Precursors are dissolved in a flammable organic solvent before being sprayed into the flame environment where they rapidly burn. Particle formation occurs on the order of 10 milliseconds. FSP has been shown to be a viable method of producing materials on an industrial scale, capable of producing grams of particles per minute. Metastable structures which exist in the liquid phase, but are difficult to synthesize using traditional impregnation methods can be formed with FSP due to fast quenching times. For example, solid solutions of Ce-Zr synthesized using FSP have been shown to have higher thermal stability when compared to Ce-Zr solid solutions made through traditional wet synthesis methods. Flame made particles have been shown to have higher activity in a variety of catalytic reactions, including oxidation reactions, photocatalytic reactions, and combustion reactions. Due to the favorable properties of solid solution FSP materials, a flame spray pyrolysis system was built using a premixed flat flame burner and atomizing nozzle for the synthesis of Ce-Mn solid solutions. Liquid solutions with varying ratios of Ce and Mn (1:1, 1:3, 3:1) were synthesized in the FSP system under a variety of different conditions. The liquid to dispersion gas ratio and atomization pressure were altered in order to determine each parameter’s effect on final particle morphology and stability. Particle morphology was characterized using x-ray diffraction and scanning electron microscopywith energy dispersive x-ray spectroscopy. Raman spectroscopy was used to determine the chemical composition of the materials, and TGA was used to determine the amount of water and carbon in the material. The hydrothermal stability of FSP made Ce- Mn solid solutions was also investigated. Samples at each atomization pressure (P=0, 0.5, 1 bar) exhibited peaks corresponding to both crystalline and amorphous ceria. The presence of amorphous ceria indicates that complete combustion is not achieved. The lattice constants for crystalline samples were calculated using Scherrer’s equation. The flame made Ce-Mn solid solutions had lower lattice constants when compared to the literature value for the lattice constant of ceria (5.411 A), indicating the incorporation of Mn into the ceria lattice. Raman and TGA data show that incomplete combustion is occurring in the flame, which matches well with the XRD data. Characterization of samples after water stability testing revealed an increase in particle size when compared to fresh samples. Pyrolysis ; Spray pyrolysis ; Catalysis ; Materials science ; Solid solution ; Chemical engineering ; Metallurgy ; Chemistry ; Nanotechnology ; Organic chemistry ; Engineering Catalytic Processes in Materials Science
Authors: Viraj Shah | Ameya Joshi | Balaji Sesha Sarath Pokuri | Sambuddha Ghosal | Soumik Sarkar | Baskar Ganapathysubramanian | Chinmay Hegde
Source: Iowa State University Digital Repository (Iowa State University) (article, 2019-01-01)
Field: Materials Science — Materials Chemistry

Binary 2D Morphologies of Polymer Phase Separation: Dataset and Python Toolbox Study of the intricate connection between the design of material distributions (also called morphology or microstructure) and the final properties of the material system has been an attractive research theme for material science community. Such analysis provides ability to synthesize the microstructures exhibiting desired properties. This theme encompasses several material systems including porous materials [26], steels and welds [2], composites [14], powder metallurgy [28], 3D printing [22], energy storage devices as batteries [10], and energy converting devices like bulk hetero-junction solar cells [20]. Microstructure-sensitive design has been used to tailor a wide variety of properties including strengths, heat and mass diffusivities, energy storage capacity and lifetime, and energy conversion efficiency. Toolbox ; Python (programming language) ; Binary number ; Computer science ; Materials science ; Mathematics ; Programming language Solidification and crystal growth phenomena ; nanoparticles nucleation surface interactions ; Block Copolymer Self-Assembly
Authors: Saeed K. Kashani | Jacob E. Jessiman | Stephen G. Newman
Source: ChemRxiv (preprint, 2019-11-06)
Field: Chemistry — Organic Chemistry

Exploring Homogeneous Conditions for Mild Buchwald-Hartwig Amination in Batch and Flow We describe the use of high throughput experimentation to identify a number of conditions that enable Buchwald-Hartwig reactions to be carried out using readily available ligands (e.g. XantPhos) with DBU as a soluble, functional group tolerant, homogeneous base. Application of this system to diverse aminations in batch and flow are demonstrated, as is the translation of this technique to performing continuous Mizoroki-Heck and Sonogashira coupling reac-tions. Amination ; Sonogashira coupling ; Xantphos ; Homogeneous ; Chemistry ; Base (topology) ; Borylation ; Combinatorial chemistry ; Organic chemistry ; Computer science ; Palladium ; Catalysis ; Mathematics ; Aryl Catalytic Cross-Coupling Reactions ; Radical Photochemical Reactions
Authors: R.L Mitchell | M. Coleman | P. Davies | L. North | E.C. Pope | C. Pleydell-Pearce | W. Harris | R. Johnston
Source: bioRxiv (Cold Spring Harbor Laboratory) (preprint, 2019-03-27)
Field: Materials Science — Biomaterials

Macro-to-nano scale investigation of wall-plate joints in the acorn barnacle <i>Semibalanus balanoides</i> : correlative imaging, biological form and function, and bioinspiration 1. Abstract Correlative imaging combines information from multiple modalities (physical-chemical-mechanical properties) at various length-scales (cm to nm) to understand complex biological materials across dimensions (2D-3D). Here, we have used numerous coupled systems: X-ray microscopy (XRM), scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), optical light microscopy (LM), and focused-ion beam (FIB-SEM) microscopy to ascertain the microstructural and crystallographic properties of the wall-plate joints in the barnacle Semibalanus balanoides . The exoskeleton is composed of six interlocking wall-plates, and the interlocks between neighbouring plates (alae) allow barnacles to expand and grow whilst remaining sealed and structurally strong. Our results indicate that the ala contain functionally-graded orientations and microstructures in their crystallography, which has implications for naturally functioning microstructures, potential natural strengthening, and preferred oriented biomineralisation. Elongated grains at the outer edge of the ala are oriented perpendicularly to the contact surface, and the c-axis rotates with the radius of the ala. Additionally, we identify for the first time three-dimensional nano-scale ala pore networks revealing that the pores are only visible at the tip of the ala, and that pore thickening occurs on the inside (soft-bodied) edge of the plates. The pore networks appear to have the same orientation as the oriented crystallography, and we deduce that the pore networks are probably organic channels and pockets which are involved with the biomineralisation process. Understanding these multi-scale features contributes towards an understanding of the structural architecture in barnacles, but also their consideration for bioinspiration of human-made materials. The work demonstrates that correlative methods spanning different length-scales, dimensions and modes enable the extension of structure-property relationships in materials to form and function of organisms. Correlative ; Microscopy ; Barnacle ; Microstructure ; Perpendicular ; Optical microscope ; Electron microscope ; Orientation (vector space) Calcium Carbonate Crystallization and Inhibition ; Marine Biology and Environmental Chemistry ; Marine and coastal plant biology
Authors: Vlad Mureşan | Mihaela-Ligia Ungureșan | Delia Gligor | Codruţa Varodi
Source: Coatings (article, 2019-07-06)
Field: Chemistry — Electrochemistry

Neural Modeling of Laviron Treatment for Coating of Electrodes with Mediator In this paper, an original solution for modeling and simulation of the nonlinear electrochemical process associated to the Laviron treatment is proposed. The graphite electrodes were coated with mediator by adsorption. The Laviron treatment was firstly used to determine the efficiency of modified electrodes coatings. The experimental data were obtained using an electrochemical experiment. The mathematical model of the process is expressed using a neural network with complex structure, an aspect which represents a novel approach in this domain. The main advantages of the proposed model are: its accuracy in relation to the experimental data and the fact that its usage permits the numerical simulation of the process, with multiple future applications. Based on the proposed neural model, an original procedure to determine the parameters of the nonlinear Laviron equation is presented. Another interesting element is represented by proving the fact that the value of heterogeneous electron-transfer rate constant kS is a function depending in the potential scan rate. This aspect is possible due to the original proposed approach of the Laviron treatment as a nonlinear process, on the entire range of input signals, in contrast with the big majority of the studies from the literature which are based on the linearization of this process near particular steady state working points. Nonlinear system ; Linearization ; Artificial neural network ; Computer science ; Process (computing) ; Transfer function ; Domain (mathematical analysis) ; Algorithm ; Biological system ; Materials science ; Artificial intelligence ; Mathematics ; Mathematical analysis ; Engineering ; Physics Electrochemical Analysis and Applications ; Conducting polymers and applications ; Electrochemical sensors and biosensors
Authors: Guillermo Restrepo
Source: arXiv (Cornell University) (preprint, 2019-08-20)
Field: Chemistry — Physical and Theoretical Chemistry

Challenges for the periodic systems of elements: chemical, historical\n and mathematical perspectives Unveiling numerical trends among either atomic or equivalent weights that\nsomehow preserved resemblances among elements was frequent in the 1860s.\nStanding out from the crowd, Meyer and Mendeleev went beyond numerical\nrelationships, certainly motivated by a pedagogical aim. Both were after a\nsystem synthesizing the chemical knowledge of their times in an appealing way\nto be presented to chemistry students. Is it still the periodic system aiming\nat that? Is it really a map of the current chemistry landscape? Solving these\nquestions entails addressing others such as: what is the periodic system? If it\nis about chemical elements, do we really know what a chemical element is? Is\nthe system unique? How was and how is currently built up? Is it actually used\nto conduct chemical research? A suitable tool for chemical predictions? Or is\nit just a mnemotechnic for fancy trends? Does it have a limit, or multiple\nones, instead? Let us try to address these questions and let us begin by\nanalysing the concept of chemical element.\n Periodic system ; Element (criminal law) ; Limit (mathematics) ; Computer science ; Epistemology ; Mathematics ; Philosophy ; Mathematical analysis ; Political science ; Law History and advancements in chemistry ; Various Chemistry Research Topics ; Chemistry and Chemical Engineering
Authors: Aslı Göçenoğlu Sarıkaya
Source: Balıkesir Üniversitesi Fen Bilimleri Enstitüsü Dergisi (article, 2019-03-15)
Field: Chemistry — Organic Chemistry

Direct Blue 2 diazo-boyarmaddesinin sulu çözeltiden P(HEMA) nanopartiküller ile uzaklaştırılması Bu çalışmada, Direct Blue 2 (DB2) diazo-boyar maddesinin poli(Hidroksietil metakrilat) [P(HEMA)] nanopartikülleri ile sulu çözeltiden giderimi çalışılmıştır.&amp;nbsp; Adsorpsiyona ortam pH’ının, sıcaklığın, başlangıç boya derişiminin ve temas süresinin etkileri incelenmiştir.&amp;nbsp; Optimum koşullar altında, 50 mg/mL başlangıç boya derişimi ve 2 mg polimer kullanılarak % 89.1 giderim elde edilmiştir.&amp;nbsp; Adsorpsiyon mekanizmasının anlaşılabilmesi için Langmuir, Freundlich ve Sips (Langmuir-Freundlich) izoterm sabitleri hesaplanmıştır.&amp;nbsp; Elde edilen verilere göre adsorpsiyonun Langmuir izoterm modeline uygun olduğu (R2: 0.993, Qmax: 27.1 mg/g) rapor edilmiştir.&amp;nbsp; Adsorpsiyon öncesi ve sonrası boya derişimleri UV-Vis spektrofotometresinde ölçülmüş, adsorpsiyon öncesi ve sonrası polimer FTIR ve SEM ile karakterize edilmiştir.&amp;nbsp; Nuclear chemistry ; Diazo ; Chemistry ; Freundlich equation ; Langmuir ; Fourier transform infrared spectroscopy ; Medicinal chemistry ; Physics ; Organic chemistry ; Adsorption Nanomaterials for catalytic reactions ; Adsorption and biosorption for pollutant removal ; Membrane Separation Technologies
Authors: Chetan Kumar Arya | Swati Yadav | Jonathan Fine | Ana Casañal | Gaurav Chopra | Gurunath Ramanathan | Kutti R. Vinothkumar | S. Ramaswamy
Source: bioRxiv (Cold Spring Harbor Laboratory) (preprint, 2019-12-18)
Field: Materials Science — Materials Chemistry

Breaking a Strong Amide Bond: Structure and Properties of Dimethylformamidase Abstract Dimethylformamidase (DMFase) breaks down the human-made synthetic solvent N,N -dimethyl formamide(DMF) used extensively in industry(1). DMF is not known to exist in nature and was first synthesized in 1893. In spite of the recent origin of DMF, certain bacterial species such as Paracoccus, Pseudomonas , and Alcaligenes have evolved pathways to breakdown DMF and use them as carbon and nitrogen source for growth(2, 3). The work presented here provides a molecular basis for the ability of DMFase from Paracoccus to function in exacting conditions of high solvent concentrations, temperature and ionic strength to catalyze the hydrolysis of a stable amide bond. The structure reveals a multimeric complex of the α 2 β 2 type or (α 2 β 2 ) 2 type. One of the three domains of the large subunit and the small subunit are hitherto undescribed folds and as yet of unknown evolutionary origin. The active site is made of a distinctive mononuclear iron that is coordinated by two tyrosine residues and a glutamic acid residue. The hydrolytic cleavage of the amide bond is catalyzed at the Fe 3+ site with a proximal glutamate probably acting as the base. The change in the quaternary structure is salt dependent with high salt resulting in the larger oligomeric state. Kinetic characterization reveals an enzyme that shows cooperativity between subunits and the structure provides clues on the interconnection between the active sites. Significance Statement N,N -dimethyl formamide(DMF) is a commonly used industrial solvent that was first synthesized in 1893. The properties that make DMF a highly desired solvent also makes it a difficult compound to breakdown. Yet, certain bacteria have evolved to survive in environments polluted by DMF and have enzymes that breakdown DMF and use it as their carbon and nitrogen source. The molecular structure of the enzyme that breaks down the stable amide bond in these bacteria, reveals two new protein folds and a unique mononuclear iron active site. The work reported here provides the structural and biochemical framework to query the evolutionary origins of the protein, as well as in engineering this enzyme for use in bioremediation of a human made toxic solvent. Chemistry ; Amide ; Formamide ; Peptide bond ; Stereochemistry ; Protein quaternary structure ; Active site ; Cooperativity ; Solvent ; Organic chemistry ; Catalysis ; Protein subunit ; Enzyme ; Biochemistry Enzyme Structure and Function ; Biochemical and Molecular Research ; Gut microbiota and health
Authors: S.K. Sadrnezhaad | Mahdis Parsafar | Y. Rashtiani | Mohsen Jadidi
Source: International Journal of Engineering (article, 2019-06-01)
Field: Materials Science — Materials Chemistry

Nitinol Spinal Vertebrae: A Favorable New Substitute Scoliosis, kyphosis, and bone fracture are health problems, especially of the elderly throughout the world. The vertebra protects the spinal cord. Any impairment to the vertebra can lead to pain and nervousness. Ni-Ti alloy (Nitinol) helps to resolve the problem by fulfilling such requirements as for strength, durability, resistance to wear, and shockwave damping which is due to the shape memory effect. Nitinol medical applications have so far been restricted to surgical devices and orthopaedics. Little has been said about Nitinol use for medication of the spinal vertebra disorder. This article appraises the potential features of Nitinol for vertebral implantation and therapeutic prescription consistent with the specific anatomical variation. Staples, screws, cages, stents, and posterior-stabilizers made of Nitinol have passed in-vitro tests and in some cases in-vivo examinations. Using anatomically tailored Nitinol for treatment and administration of the damaged vertebra is proposed as a forecastable dream. Vertebra ; Kyphosis ; Medicine ; Scoliosis ; Spinal cord ; Shape-memory alloy ; Implant ; Orthodontics ; Surgery ; Materials science ; Radiography ; Metallurgy Shape Memory Alloy Transformations ; Aortic Disease and Treatment Approaches ; Spinal Fractures and Fixation Techniques
Authors: Ya Zhuo | Jiyou Zhong | Jakoah Brgoch
Source: ChemRxiv (preprint, 2019-11-06)
Field: Materials Science — Materials Chemistry

Controlling Eu2+ Substitution towards a Narrow-Band Green-Emitting Borate Phosphor NaBaB9O15:Eu2+ Highly efficient, thermally stable, narrow-band phosphors that can be excited by a blue LED chip are crucial for energy-efficient light bulbs and display lighting. Here, a rare narrow-band, green-emitting phosphor based on the compound NaBaB9O15:Eu2+ is demonstrated. The emission peak is centered at 515 nm with a full-width at half-maximum (fwhm) of 61 nm (2294 cm−1), and a photoluminescence quantum yield of >80% using blue or near-UV LED excitation. This borate’s remarkable green emission stems from Eu2+ substituting on the smaller [NaO6] polyhedron instead of the larger and more favorable [BaO9] polyhedron. The phosphor also exhibits negligible thermal quenching up to 650 K owing to the wide band gap, high connectivity of the rigid NaBaB9O15 crystal structure, and the depopulation of trap-states. This combination of optical properties and its straightforward synthesis conditions makes NaBaB9O15:Eu2+ an ideal green phosphor for next-generation LED-based lighting or display systems. Phosphor ; Full width at half maximum ; Photoluminescence ; Materials science ; Excited state ; Optoelectronics ; Band gap ; Luminescence ; Crystal structure ; Boron ; Quantum efficiency ; Chemistry ; Crystallography ; Physics ; Atomic physics Luminescence Properties of Advanced Materials ; Radiation Detection and Scintillator Technologies ; Perovskite Materials and Applications