jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: V. V. Savinkin | Petrică Vizureanu | Andrei Victor Sandu | Tatyana Yu. Ratushnaya | Andrey A. Ivanischev | Andriana Surleva
Source: Coatings (article, 2020-01-10)
Field: Materials Science — General Materials Science

Improvement of the Turbine Blade Surface Phase Structure Recovered by Plasma Spraying This paper presents the results of research on the construction, technological parameters and criteria that control the process of formation of optimal phase structure of austenitic- and martensitic-class material for steam turbine blades. The hypothesis that the established correlation could increase the quality of blade recovery and its resistance against dynamic and vibrational loads was proved. The efficiency of the developed implantation method for the recovery of steam turbine blades was demonstrated. The optimal technological parameters of the process of laser plasma recovery were established empirically, allowing the development of the system for the fine tuning of the phase composition of austenitic- and martensitic-class steel. Steam turbine ; Martensite ; Turbine blade ; Austenite ; Materials science ; Blade (archaeology) ; Turbine ; Plasma ; Process (computing) ; Phase (matter) ; Metallurgy ; Mechanical engineering ; Microstructure ; Computer science ; Engineering ; Chemistry Material Properties and Applications ; Surface Treatment and Coatings ; Coal Combustion and Slurry Processing
Authors: Xiaoli Wang | Xingfa Gao
Source: The Journal of Physical Chemistry C (article, 2020-04-17)
Field: Materials Science — Materials Chemistry

Substituent Effects on Electronic Structures and Peroxidase-Mimicking Activities of Graphyne and Palladium-Doped Graphyne: A Computational Study The substituent effects on the electronic structures and peroxidase-mimicking activities of γ-graphyne (GY) and Pd-doped GY are studied by density functional theory calculations. Both the inductive and mesomeric effects of the substituents significantly influence the electronic structures of GY and its derivatives. However, the complexation strength between Pd atoms and GY is mainly affected by the long-range mesomeric effect rather than the short-range inductive effect of the substituents. The pristine GY hardly has peroxidase-mimicking activity because H2O2 molecules strongly chemisorb on the triple bonds in the form of hydroxyl groups. However, GY doped with Pd atoms, namely, Pd@GY, has greatly enhanced peroxidase-mimicking activity. The activity can be further tuned by decorating Pd@GY with external functional groups. The decorated groups alter not only the rate-limiting reaction steps of the catalysis but also the energies associated with the reactions. Pd@GY decorated with F atoms may have the largest peroxidase-mimicking activity among that of the substituents studied here. The results provide an in-depth understanding of the substituent effects on the electronic structures of GY and Pd@GY and suggest the potential of chemical functionalization in fine-tuning the peroxidase-mimicking activities of the materials. Graphyne ; Substituent ; Chemistry ; Density functional theory ; Peroxidase ; Palladium ; Catalysis ; Electronic effect ; Photochemistry ; Computational chemistry ; Stereochemistry ; Organic chemistry ; Enzyme Advanced Nanomaterials in Catalysis ; Carbon and Quantum Dots Applications ; Nanocluster Synthesis and Applications
Authors: A. D’Elia | Cesare Grazioli | Albano Cossaro | B.W. Li | Chongwen Zou | S.J. Rezvani | N. Pinto | A. Marcelli | Marcello Coreno
Source: Applied Surface Science (article, 2020-11-03)
Field: Materials Science — Polymers and Plastics

Strain mediated Filling Control nature of the Metal-Insulator Transition of VO2 and electron correlation effects in nanostructured films Condensed matter physics ; Metal–insulator transition ; Electronic correlation ; Materials science ; Fermi level ; Phase transition ; Electron ; Strongly correlated material ; X-ray photoelectron spectroscopy ; XANES ; Spectroscopy ; Metal ; Physics ; Nuclear magnetic resonance Transition Metal Oxide Nanomaterials ; Ga2O3 and related materials ; ZnO doping and properties
Authors: Samrat Ghosh | Akinobu Nakada | Maximilian A. Springer | Takahiro Kawaguchi | Katsuaki Suzuki | Hironori Kaji | Igor A. Baburin | Agnieszka Kuc | Thomas Heine | Ryu Abe | Shu Seki
Source: ChemRxiv (preprint, 2020-03-09)
Field: Materials Science — Materials Chemistry

Identification of Prime Factors to Maximize the Photocatalytic Hydrogen Evolution of Covalent Organic Frameworks Visible light driven hydrogen (H2) production from water is a promising strategy to convert and store solar energy as chemical energy. Covalent organic frameworks (COFs) are front runners among different classes of organic photocatalyst, owing to their tunable porosity, crystallinity, optical and electronic properties. Photocatalytic activity of COFs depends on numerous factors such as band gap, crystallinity, porosity, exciton migration, charge separation and transport, stability etc. However, it is challenging to fine tune all these factors simultaneously to enhance the photocatalytic activity. Hence, in this report, we have prioritized the key factors for efficient photocatalytic H2 production through structure–property–activity relationship combined with microwave spectroscopy and first–principles calculations. Careful molecular engineering allowed us to tune the light absorption (i.e. band gap), crystallinity, porosity, layer stacking and charge carrier generation and transport of a series of isoreticular COFs. We have assessed how these properties and the interplay between them impact photocatalytic activity of studied COFs. From the structure–property–activity relationship, we found that light absorption and charge carrier generation and transport are the prime factors, which influence the photocatalytic H2 production of COFs in much greater extent than other factors. Photocatalysis ; Crystallinity ; Materials science ; Hydrogen production ; Absorption (acoustics) ; Porosity ; Band gap ; Stacking ; Charge carrier ; Covalent bond ; Chemical engineering ; Nanotechnology ; Photochemistry ; Hydrogen ; Optoelectronics ; Chemistry ; Catalysis ; Composite material ; Organic chemistry Covalent Organic Framework Applications ; Advanced Photocatalysis Techniques ; Catalytic Processes in Materials Science
Authors: Luís F. B. Fontes | Raquel Nunes da Silva | Artur M. S. Silva | Samuel Guieu
Source: ChemPhotoChem (article, 2020-07-04)
Field: Materials Science — Materials Chemistry

Unsymmetrical 2,4,6‐Triarylpyridines as Versatile Scaffolds for Deep‐Blue and Dual‐Emission Fluorophores Abstract Pyridines substituted with different aromatic groups at C‐2, C‐4 and C‐6 were prepared following a Kröhnke synthetic route. Introducing ortho ‐anisole at C‐2 resulted in deep blue emitters in solution, with quantum yields up to 74 %. On the other hand, when ortho ‐phenol was introduced, forming a strong hydrogen bond with the pyridine nitrogen, excited‐state intramolecular proton transfer was witnessed by the dual emission of the fluorophores, which is sensitive to the dye environment. The phenyl ring at C‐4 was used to introduce electron‐donating or withdrawing groups, to fine‐tune the photophysical properties of the dyes. Crystal structures of the fluorophores, together with theoretical studies using DFT/TD‐DFT calculations, were used to rationalize the experimental photophysical properties of the two families of dyes. Unsymmetrical 2,4,6‐triarylpyridines are therefore versatile scaffolds for the preparation of deep‐blue and dual emission fluorophores, and are promising building blocks for luminescent devices and sensors. Intramolecular force ; Pyridine ; Photochemistry ; Anisole ; Excited state ; Luminescence ; Chemistry ; Phenol ; Hydrogen bond ; Fluorescence ; Ring (chemistry) ; Materials science ; Combinatorial chemistry ; Molecule ; Optoelectronics ; Organic chemistry Luminescence and Fluorescent Materials ; Synthesis and Properties of Aromatic Compounds ; Organic Light-Emitting Diodes Research
Authors: R. Narendran | Archita Patnaik
Source: Soft Matter (article, 2020-11-17)
Field: Chemistry — Spectroscopy

Synergistic effect of hydrophobic and hydrogen bonding interaction-driven viologen–pyranine charge-transfer aggregates: adenosine monophosphate recognition Understanding the role of non-covalent interactions that dictate and fine-tune the direction of self-assembly of functional molecules is crucial for developing stimuli responsive materials. Herein, we systematically designed and synthesized viologen derivatives with hydrophobic dodecyl chains and alkyl carboxylic acid functionalities. The complementary electronic and electrostatic counterpart of viologens was chosen as pyranine. Viologens comprising of a hydrophobic dodecyl chain on one terminal and hydrogen bonding alkyl carboxylic acid on the other (V1 and V2) underwent aggregation to a varying extent upon interaction with pyranine. The length of the alkyl carboxylic acid had a greater impact on the nature and morphology of the aggregates. Control molecules (V3 and V4) in which 4,4'-bipyridine was symmetrically quaternized with alkyl carboxylic acids did not aggregate upon interaction with pyranine. The delicate balance existing between the hydrophobicity of the dodecyl chains and the intermolecular hydrogen bonding interaction between the alkyl carboxylic acid groups in V1 or V2 of the corresponding charge transfer (CT) complexes was instrumental in driving the aggregation. The CT aggregates of [V1-Pyr] and [V2-Pyr] exhibited excellent stability in water which disaggregated at physiological pH. We emphasize on the importance of synergy between hydrophobic and hydrogen bonding interactions in reinforcing each other to drive the supramolecular aggregation of the CT complexes. Such pH dependent CT aggregates are of importance as scaffolds in pH controlled drug release. In the present study, the CT aggregates were evaluated for adenosine nucleotide recognition in water; [V1-Pyr] and [V2-Pyr] exhibited selective response towards adenosine monophosphate via deprotonation induced dissolution of aggregates in water leading to emission enhancement. Pyranine ; Viologen ; Chemistry ; Hydrophobic effect ; Hydrogen bond ; Microscale chemistry ; Covalent bond ; Molecule ; Photochemistry ; Biophysics ; Organic chemistry ; Biochemistry ; Membrane Molecular Sensors and Ion Detection ; Supramolecular Self-Assembly in Materials ; Luminescence and Fluorescent Materials
Authors: Paulo De Carvalho Gomes | Jonathan James Stanley Rickard | Pola Goldberg Oppenheimer
Source: ACS Applied Nano Materials (article, 2020-06-22)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Electrofluidynamic Patterning of Tailorable Nanostructured Substrates for Surface-Enhanced Raman Scattering The unique attributes of surface enhanced Raman spectroscopy (SERS) make it well suited to address the challenges associated with portable diagnostics. However, despite the remarkable progress in this field, where the instrumentation has made great strides forward providing a route to the miniaturization of sensing devices, to date producing three-dimensional low-cost SERS substrates which simultaneously fulfill the multitude of criteria of high sensitivity, reproducibility, tunability, multiplexity, and integratability for rapid sensing has not yet been accomplished. Successful implementation of SERS requires readily fine-tuned nanostructures, which create a high enhancement. Here, an advanced electrofluidynamic patterning (EFDP) technique enables rapid fabrication of SERS active topographic morphologies with high throughput and at a nanoresolution via the spatial and lateral modulation of the dielectric discontinuity due to the high electric field generated across the polymer nanofilm and air gap. The subsequent formation of displacement charges within the nanofilm by coupling to the electric field yield a destabilizing electrostatic pressure and amplification of EFDP instabilities enabling the controllable pattern formation. The top of each gold coated EFDP fabricated pillar generates controllable high SERS enhancement by coupling of surface plasmon modes on top of the pillar, with each nanostructure acting as an individual sensing unit. The absolute enhancement factor depends on the topology as well as the tunable dimensions of the nanostructured units, and these are optimized in the design and engineering of the dedicated EFDP apparatus for reproducible, low-cost fabrication of the three-dimensional nanoarchitectures on macrosurfaces, rendering them for easy integration in further lab-on-a-chip devices. This unique combination of nanomaterials and nanospectroscopic systems lay the platform for a variety of applications in chemical and biological sensing. Materials science ; Nanotechnology ; Fabrication ; Miniaturization ; Nanostructure ; Plasmon ; Raman scattering ; Dielectric ; Optoelectronics ; Raman spectroscopy ; Optics Gold and Silver Nanoparticles Synthesis and Applications ; Biosensors and Analytical Detection ; Electrohydrodynamics and Fluid Dynamics
Authors: Md. Mehboob Alam | Maarten T. P. Beerepoot | Kenneth Ruud
Source: The Journal of Chemical Physics (article, 2020-06-22)
Field: Materials Science — Electronic, Optical and Magnetic Materials

A generalized few-state model for the first hyperpolarizability The properties of molecules depend on their chemical structure, and thus, structure-property relations help design molecules with desired properties. Few-state models are often used to interpret experimental observations of non-linear optical properties. Not only the magnitude but also the relative orientation of the transition dipole moment vectors is needed for few-state models of the non-linear optical properties. The effect of the relative orientation of the transition dipole moment vectors is called dipole alignment, and this effect has previously been studied for multiphoton absorption properties. However, so far, no such studies are reported for the first hyperpolarizability. Here, we present a generalized few-state model for the static and dynamic first hyperpolarizability β, accounting for the effect of dipole alignment. The formulas derived in this work are general in the sense that they can be used for any few-state model, i.e., a two-state model, a three-state model, or, in general, an n-state model. Based on the formulas, we formulate minimization and maximization criteria for the alignment of transition dipole moment vectors. We demonstrate the importance of dipole alignment by applying the formulas to the static first hyperpolarizability of ortho-, meta-, and para-nitroaniline. The formulas and the analysis provide new ways to understand the structure-property relationship for β and can hence be used to fine-tune the magnitude of β in a molecule. Hyperpolarizability ; Dipole ; Moment (physics) ; Statistical physics ; Transition dipole moment ; Orientation (vector space) ; Physics ; Computational chemistry ; Mathematics ; Chemistry ; Quantum mechanics ; Nonlinear system ; Geometry ; Nonlinear optical Nonlinear Optical Materials Research ; Nonlinear Optical Materials Studies ; Synthesis and Properties of Aromatic Compounds
Authors: Felix Unglaube | Paul Hünemörder | Xuewen Guo | Zixu Chen | Dengxu Wang | Esteban Mejía
Source: Helvetica Chimica Acta (article, 2020-11-11)
Field: Chemistry — Organic Chemistry

Phenazine Radical Cations as Efficient Homogeneous and Heterogeneous Catalysts for the Cross‐Dehydrogenative Aza‐<i>Henry</i> Reaction Abstract The redox activity of molecular phenazine catalysts has been previously exploited for aerobic oxidative amine homo‐ and cross‐coupling reactions. In this contribution, we have extended the reaction scope of this novel type of organocatalyst and used them in the cross‐dehydrogenative aza‐ Henry coupling of isoquinolines with nitromethane under aerobic conditions. Additionally, we have designed and prepared a novel porous organic polymer by cross‐linking of tetrakis(4‐bromophenyl)silane and dihydrophenazine through Pd‐catalyzed Buchwald‐Hartwig cross‐coupling. This new type of heterogeneous catalyst, apart from being robust and easily reusable, also showed outstanding catalytic activities and improved selectivity compared to its molecular counterpart. A plausible reaction mechanism was proposed based on spectroscopic and kinetic measurements. Chemistry ; Nitromethane ; Phenazine ; Catalysis ; Coupling reaction ; Selectivity ; Nitroaldol reaction ; Amine gas treating ; Redox ; Combinatorial chemistry ; Photochemistry ; Organic chemistry ; Enantioselective synthesis Catalytic C–H Functionalization Methods ; Covalent Organic Framework Applications ; Radical Photochemical Reactions
Authors: Marta Piątek-Hnat | Kuba Bomba | Jakub Pęksiński
Source: Molecules (article, 2020-03-28)
Field: Materials Science — Biomaterials

Structure and Properties of Biodegradable Poly (Xylitol Sebacate-Co-Butylene Sebacate) Copolyester In this work, a bio-based copolyester with good mechanical properties was synthesized and characterized in terms of structure, main properties and biodegradability Determining the chemical structure of such materials is important to understand their behavior and properties. Performing an extraction of insoluble cross-linked polymer using different solvents allowed us to analyze how the polymer behaves when subjected to different chemical environments, and to obtain soluble samples suitable for more in-depth analysis. Chemical structure of poly (xylitol sebacate-co-butylene sebacate) was determined by a <sup>1</sup>H NMR and FTIR analysis of both prepolymer gel sample and samples obtained by extraction of cross-linked polymer using different solvents. Block structure of the copolymer was confirmed by both NMR and DSC. Gel fraction, swelling value, water contact angle, and mechanical properties were also analyzed. Biodegradability of this material was confirmed by performing enzymatic and hydrolytic degradation. Synthesizing sugar-alcohol based copolyester using three monomers leads to obtaining a material with interesting chemical structure and desirable mechanical properties comparable to conventional elastomers. Copolyester ; Materials science ; Polymer ; Biodegradation ; Prepolymer ; Chemical structure ; Elastomer ; Chemical engineering ; Copolymer ; Fourier transform infrared spectroscopy ; Monomer ; Polymer chemistry ; Composite material ; Organic chemistry ; Chemistry ; Polyester ; Polyurethane biodegradable polymer synthesis and properties ; Electrospun Nanofibers in Biomedical Applications ; Enzyme Catalysis and Immobilization
Authors: Lars May | Thomas J. J. Müller
Source: Molecules (review, 2020-05-07)
Field: Materials Science — Materials Chemistry

Dithieno[1,4]thiazines and Bis[1]benzothieno[1,4]thiazines—Organometallic Synthesis and Functionalization of Electron Density Enriched Congeners of Phenothiazine This mini-review summarizes the syntheses and functionalizations of dithieno[1,4]thiazines and bis[1]benzothieno[1,4]thiazines, both electron density-enriched congeners of phenothiazines with remarkable electronic properties. Diversity-oriented, straightforward, and efficient syntheses, including versatile one-pot processes, have been developed for the anellated 1,4-thiazines as well as various functionalization for the expansion of the π-systems. Thereby, syntheses of different regioisomers depending on the (benzo)thieno-thiazine anellation are discussed, which exert a deep impact on the electronic properties. The tunable photophysical and electrochemical properties of dithieno[1,4]thiazines and bis[1]benzothieno[1,4]thiazines outscore phenothiazines on many points and promise an enormous potential in molecular electronics and applications beyond. Phenothiazine ; Surface modification ; Thiazine ; Combinatorial chemistry ; Electrochemistry ; Chemistry ; Organic chemistry ; Physical chemistry Porphyrin and Phthalocyanine Chemistry ; Luminescence and Fluorescent Materials ; Photochromic and Fluorescence Chemistry
Authors: Carlos Bartual‐Murgui | Cristian Pérez-Padilla | Simon J. Teat | Olivier Roubeau | Guillem Aromı́
Source: Inorganic Chemistry (article, 2020-08-19)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Allosteric Spin Crossover Induced by Ligand-Based Molecular Alloying The spin crossover (SCO) phenomenon represents a source of multistability at the molecular level, and dilution into a nonactive host was originally key to understand its cooperative nature and the parameters governing it in the solid state. Here, we devise a molecular alloying approach in which all components are SCO-active, but with significantly different characteristic temperatures. Thus, the molecular material [Fe(Mebpp)<sub>2</sub>](ClO<sub>4</sub>)<sub>2</sub> (<b>2</b>) has been doped with increasing amounts of the ligand Me2bpp (Mebpp and Me2bpp = methyl- and bis-methyl-substituted bis-pyrazolylpyridine ligands), yielding molecular alloys with the formula [Fe(Mebpp)<sub>2-2<i>x</i></sub>(Me2bpp)<sub>2<i>x</i></sub>](ClO<sub>4</sub>)<sub>2</sub> (<b>4</b><i>x</i>; 0.05 < <i>x</i> < 0.5). The effect of the composition on the SCO process is studied through single-crystal X-ray diffraction (SCXRD), magnetometry, and differential scanning calorimetry (DSC). While the attenuation of intermolecular interactions is shown to have a strong effect on the SCO cooperativity, the spin conversion was found to occur at intermediate temperatures and in one sole step for all components of the alloys, thus unveiling an unprecedented allosteric SCO process. This effect provides in turn a means of tuning the SCO temperature within a range of 42 K. Chemistry ; Spin crossover ; Differential scanning calorimetry ; Cooperativity ; Ligand (biochemistry) ; Intermolecular force ; Crystallography ; Spin transition ; Allosteric regulation ; Spin states ; Molecule ; Thermodynamics ; Inorganic chemistry ; Organic chemistry Magnetism in coordination complexes ; Lanthanide and Transition Metal Complexes ; Metal-Catalyzed Oxygenation Mechanisms
Authors: Marie Gestranius | Issei Otsuka | Sami Halila | Daniel Hermida‐Merino | Eduardo Solano | Rédouane Borsali | Tekla Tammelin
Source: Advanced Materials Interfaces (article, 2020-02-16)
Field: Materials Science — Biomaterials

High‐Resolution Patterned Biobased Thin Films via Self‐Assembled Carbohydrate Block Copolymers and Nanocellulose Abstract The exploitation of the effortless self‐assembly behavior of biomass‐based bricks can be seen as a promising route toward the innovative architectures. Here, a straightforward approach is presented where carbohydrate‐based diblock copolymer, polystyrene‐ block ‐maltoheptaose (PS‐ b ‐MH), is organized either on a rigid ultrathin film or on a flexible self‐standing film of wood‐derived cellulose nanofibrils (CNFs). During solvent annealing PS‐ b ‐MH deposited on relatively rough CNF film undergoes spontaneous rearrangement into high‐resolution patterns with a diblock domain spacing of 10–15 nm. The ideal conditions the self‐assembly require weak interactions between block copolymer and the substrate to increase the chain mobility and enable rearrangements. This is exactly how the system behaves. Adsorption studies of PS‐ b ‐MH on CNF surfaces reveal weak interactions, and the formed PS‐ b ‐MH layer is soft and mobile. Even the appearance of more challenging vertical orientation formed on smooth CNF substrates is tentatively evidenced by grazing‐incidence small‐angle X‐ray scattering and atomic force microscope indicating favorable surface interactions between CNF and PS‐ b ‐MH. Materials science ; Copolymer ; Nanocellulose ; Cellulose ; Polystyrene ; Chemical engineering ; Self-assembly ; Thin film ; Grazing-incidence small-angle scattering ; Annealing (glass) ; Polymer chemistry ; Nanotechnology ; Scattering ; Composite material ; Polymer ; Optics Advanced Cellulose Research Studies ; Pickering emulsions and particle stabilization ; Block Copolymer Self-Assembly