jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Pavol Ondrisek | Margaux Elie | Marion Pupier | Adiran de Aguirre | Amalia I. Poblador‐Bahamonde | Céline Besnard | Jérôme Lacour
Source: Chemistry - A European Journal (article, 2022-01-18)
Field: Chemistry — Organic Chemistry

Acetylene Derivatives of Cationic Diazaoxatriangulenes and Diaza [4]Helicenes ‐ Access to Red Emitters and Planar Chiral Stereochemical Traits Cationic triangulenes, and related helicenes, constitute a rich class of dyes and fluorophores, usually absorbing and emitting light at low energy, in the orange to red domains. Recently, to broaden the scope of applications, regioselective late-stage functionalizations on these core moieties have been developed. For instance, with the introduction of electron-donating groups (EDGs), important bathochromic shifts are observed pushing absorptions towards or in the near-infrared (NIR) spectral domain while emissive properties disappear essentially completely. Herein, to upset this drawback, acetylene derivatives of cationic diazaoxa triangulenes (DAOTA) and [4]helicenes are prepared (16 examples). Contrary to other EDG-functionalized derivatives, C≡C- functionalized products remain broadly fluorescent, with red-shifted absorptions (Δλ<sub>abs</sub> up to 25 nm) and emissions (Δλ<sub>em</sub> up to 73 nm, Φ<sub>PL</sub> up to 51 %). Quite interestingly, a general dynamic stereoisomerism phenomenon is evidenced for the compounds derived from achiral DAOTA cores. At low temperature in <sup>1</sup> H NMR spectroscopy (218 K), N-CH<sub>2</sub> protons become diastereotopic with chemical shifts differences (Δδ) as high as +1.64 ppm. The signal coalescence occurs around 273 K with a barrier of ∼12 kcal mol<sup>-1</sup> . This phenomenon is due to planar chiral conformations (S<sub>p</sub> and R<sub>p</sub> configurations), induced by the geometry of the alkyl (n-propyl) side-chains next to the acetylenic substituents. Ion pairing studies with Δ-TRISPHAT anion not only confirm the occurrence of the chiral conformations but evidence a moderate but definite asymmetric induction from the chiral anion onto the cations. Finally, DFT calculations offer a valuable insight on the geometries, the corresponding stereodynamics and also on the very large difference in NMR for some of the diastereotopic protons. Cationic polymerization ; Chemistry ; Alkyl ; Regioselectivity ; Acetylene ; Photochemistry ; Stereochemistry ; Crystallography ; Organic chemistry ; Catalysis Synthesis and Properties of Aromatic Compounds ; Luminescence and Fluorescent Materials ; Photochromic and Fluorescence Chemistry
Authors: Qian Xiao | Wenliang Zhang | Teguh Citra Asmara | Dong Li | Qizhi Li | Shilong Zhang | Yi Tseng | Xiaoli Dong | Yao Wang | Cheng-Chien Chen | Thorsten Schmitt | Y. Y. Peng
Source: npj Quantum Materials (article, 2022-08-18)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Dispersionless orbital excitations in (Li,Fe)OHFeSe superconductors Abstract The superconducting critical temperature T c of intercalated iron-selenide superconductor (Li,Fe)OHFeSe (FeSe11111) can be increased to 42 from 8 K of bulk FeSe. It shows remarkably similar electronic properties as the high- T c monolayer FeSe and provides a bulk counterpart to investigate the origin of enhanced superconductivity. Unraveling the nature of excitations is crucial for understanding the pairing mechanism in high- T c iron selenides. Here we use resonant inelastic x-ray scattering (RIXS) to investigate the excitations in FeSe11111. Our high-quality data exhibit several Raman-like excitations, which are dispersionless and isotropic in momentum transfer in both superconducting 28 K and 42 K samples. Using atomic multiplet calculations, we assign the low-energy ~0.3 and 0.7 eV Raman peaks as local e g − e g and e g − t 2 g orbital excitations. The intensity of these two features decreases with increasing temperature, suggesting a dominating contribution of the orbital fluctuations. Our results highlight the importance of the orbital degree of freedom for high- T c iron selenides. Superconductivity ; Physics ; Condensed matter physics ; Raman spectroscopy ; Resonant inelastic X-ray scattering ; Pairing ; Selenide ; Raman scattering ; Antiferromagnetism ; Energy (signal processing) ; Chemistry ; X-ray Raman scattering ; Quantum mechanics Iron-based superconductors research ; Rare-earth and actinide compounds ; Corporate Taxation and Avoidance
Authors: Danuta Raj
Source: Molecules (article, 2022-05-05)
Field: Chemistry — Spectroscopy

Eutectic Thin-Layer Chromatography as a New Possibility for Quantification of Plant Extracts—A Case Study Deep eutectic solvents (DES), compared to classic ones, have interesting properties, such as the ability to solubilize compounds differing in polarity or increased dissolution of selected chemical compounds. They also offer specific interactions between the mobile and stationary phases. Those features make them promising solvents in chromatographic techniques, including the use in the separation of complicated samples. The first quantitative analysis with eutectic thin-layer chromatography (TLC) is presented in the paper. As a case study, five alkaloids from <i>Chelidonium maius</i> were selected as target compounds. A wide range of terpene-based DESs was investigated to develop the chromatographic system, both pure and after dilution. Moreover, a novel approach was employed to adjust polarity, involving mixing DESs differing in chromatographic properties. This procedure has proved to be effective. The best results were obtained with a 2:1 (wt/wt) mixture of DESs: camphor + phenol and menthol + limonene, with a 20% addition of methanol. The chromatographic system was validated and checked on the real sample, which made it the first applicable and operational quantitative eutectic TLC system. Chromatography ; Chemistry ; Menthol ; Eutectic system ; Camphor ; Phenol ; Thin-layer chromatography ; Dilution ; Methanol ; Organic chemistry Analytical Chemistry and Chromatography ; Ionic liquids properties and applications ; Chemical synthesis and alkaloids
Authors: Guiomar Delgado Soria | K. Freindl | J. E. Prieto | Adrián Quesada | Juan de la Figuera | N. Spiridis | J. Korecki | José F. Marco
Source: Applied Surface Science (article, 2022-02-12)
Field: Materials Science — Materials Chemistry

Growth and characterization of ultrathin cobalt ferrite films on Pt(111) Annealing (glass) ; Materials science ; Cobalt ; Analytical Chemistry (journal) ; Auger electron spectroscopy ; Molecular beam epitaxy ; Spinel ; Thin film ; Oxygen ; Crystallography ; Chemistry ; Metallurgy ; Nanotechnology ; Epitaxy Magnetic Properties and Synthesis of Ferrites ; Magnetic properties of thin films ; Multiferroics and related materials
Authors: Arnab Ganguly | Gobind Das
Source: Nanomaterials (article, 2022-10-04)
Field: Materials Science — Surfaces, Coatings and Films

Combining Azimuthal and Polar Angle Resolved Shadow Mask Deposition and Nanosphere Lithography to Uncover Unique Nano-Crystals In this article, we present a systematic investigation on a multistep nanosphere lithography technique to uncover its potential in fabricating a wide range of two- and three-dimensional nanostructures. A tilted (polar angle) electron beam shower on a nanosphere mask results in an angled shadow mask deposition. The shape of the shadow also depends on the azimuthal angle of the mask sitting on top of the substrate. We performed angled shadow mask depositions with systematic variation of these two angular parameters, giving rise to complex nanostructures (down to 50 nm), repeated over a large area without defect. In this article, nanosphere lithography with two- and four-fold azimuthal symmetry was studied at constant tilt angles followed by variations in tilt without azimuthal rotation of the substrate. Finally, both angular parameters were simultaneously varied. The structure of shadow crystals was explained using Matlab simulation. This work stretches the horizons of nanosphere lithography, opening up new scopes in plasmonic and magnonic research. Nanosphere lithography ; Azimuth ; Optics ; Materials science ; Tilt (camera) ; Lithography ; Substrate (aquarium) ; Deposition (geology) ; Rotation (mathematics) ; Shadow mask ; Electron-beam lithography ; Nanotechnology ; Physics ; Resist ; Geometry Optical Coatings and Gratings ; Nanofabrication and Lithography Techniques ; Plasmonic and Surface Plasmon Research
Authors: Jungho Shin | Fulin Wang | Glenn H. Balbus | Tianjiao Lei | Timothy J. Rupert | Daniel S. Gianola
Source: Journal of materials research/Pratt's guide to venture capital sources (article, 2022-09-08)
Field: Materials Science — Materials Chemistry

Optimizing thermal stability and mechanical behavior in segregation-engineered nanocrystalline Al–Ni–Ce alloys: A combinatorial study Materials science ; Nanocrystalline material ; Annealing (glass) ; Thermal stability ; Microstructure ; Grain boundary ; Grain size ; Homogeneous ; Thermal ; Grain growth ; Chemical engineering ; Metallurgy ; Composite material ; Chemical physics ; Thermodynamics ; Nanotechnology Microstructure and mechanical properties ; Aluminum Alloys Composites Properties ; Aluminum Alloy Microstructure Properties
Authors: Veronika Kovacova | Sebastjan Glinšek | Stéphanie Girod | Emmanuel Defaÿ
Source: Sensors (article, 2022-05-27)
Field: Materials Science — Materials Chemistry

High Electrocaloric Effect in Lead Scandium Tantalate Thin Films with Interdigitated Electrodes Lead scandium tantalate, Pb(Sc,Ta)O<sub>3</sub>, is an excellent electrocaloric material showing large temperature variations, good efficiency, and a broad operating temperature window. In form of multilayer ceramic capacitors integrated into a cooling device, the device can generate a temperature difference larger than 13 K. Here, we investigate Pb(Sc,Ta)O<sub>3</sub> in form of thin films prepared using the sol-gel chemical solution deposition method. We report the detailed fabrication process of high-quality films on various substrates such as c-sapphire and fused silica. The main originality of this research is the use of interdigitated top electrodes, enabling the application of very large electric fields in PST. We provide structural and electrical characterisation, as well as electrocaloric temperature variation, using the Maxwell relation approach. Films do not show a B-site ordering. The temperature variation from 7.2 to 15.7 K was measured on the Pb(Sc,Ta)O<sub>3</sub> film on a c-sapphire substrate under the electric field of 1330 kV/cm between 14.5 °C and 50 °C. This temperature variation is the highest reported so far in Pb(Sc,Ta)O<sub>3</sub> thin films. Moreover, stress seems to have an effect on the maximum permittivity temperature and thus electrocaloric temperature variation with temperature in Pb(Sc,Ta)O<sub>3</sub> films. Tensile stress induced by fused silica shifts the "transition" of Pb(Sc,Ta)O<sub>3</sub> to lower temperatures. This study shows the possibility for electrocaloric temperature variation tuning with stress conditions. Materials science ; Electrocaloric effect ; Thin film ; Electric field ; Sapphire ; Substrate (aquarium) ; Ferroelectricity ; Ceramic ; Pyroelectricity ; Dielectric ; Optoelectronics ; Composite material ; Nanotechnology ; Optics Ferroelectric and Piezoelectric Materials ; Microwave Dielectric Ceramics Synthesis ; Dielectric materials and actuators
Authors: Jordan Baglo | Jiasheng Chen | Keiron Murphy | Roos Leenen | A. McCollam | Michael Sutherland | F. M. Grosche
Source: Physical Review Letters (article, 2022-07-20)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Fermi Surface and Mass Renormalization in the Iron-Based Superconductor <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mrow><mml:msub><mml:mrow><mml:mi>YFe</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow><mml:mrow><mml:msub><mml:mrow><mml:mi>Ge</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:mrow></mml:math> Interaction-enhanced carrier masses are central to the phenomenology of iron-based superconductors. Quantum oscillation measurements in the new unconventional superconductor YFe_{2}Ge_{2} resolve all four Fermi surface pockets expected from band structure calculations, which predict an electron pocket in the Brillouin zone corner and three hole pockets enveloping the centers of the top and bottom of the Brillouin zone. Carrier masses reach up to 20 times the bare electron mass and are among the highest ever observed in any iron-based material, accounting for the enhanced heat capacity Sommerfeld coefficient ≃100 mJ/mol K^{2}. Mass renormalization is uniform across reciprocal space, suggesting predominantly local correlations, as in the Hund's metal scenario. Renormalization ; Physics ; Fermi surface ; Superconductivity ; Condensed matter physics ; Mathematical physics Iron-based superconductors research ; Rare-earth and actinide compounds ; Physics of Superconductivity and Magnetism
Authors: Amanda C. Daulagala | Antonis Kourtidis
Source: Cells (article, 2022-11-23)
Field: Materials Science — Biomaterials

ECM Substrates Impact RNAi Localization at Adherens Junctions of Colon Epithelial Cells The extracellular matrix (ECM) plays crucial roles in tissue homeostasis. Abnormalities in ECM composition are associated with pathological conditions, such as fibrosis and cancer. These ECM alterations are sensed by the epithelium and can influence its behavior through crosstalk with other mechanosensitive complexes, including the adherens junctions (AJs). We have previously shown that the AJs, through their component PLEKHA7, recruit the RNAi machinery to regulate miRNA levels and function. We have particularly shown that the junctional localization of RNAi components is critical for their function. Here, we investigated whether different ECM substrates can influence the junctional localization of RNAi complexes. To do this, we plated colon epithelial Caco2 cells on four key ECM substrates found in the colon under normal or pathogenic conditions, namely laminin, fibronectin, collagen I, and collagen IV, and we examined the subcellular distribution of PLEKHA7, and of the key RNAi components AGO2 and DROSHA. Fibronectin and collagen I negatively impacted the junctional localization of PLEKHA7, AGO2, and DROSHA when compared to laminin. Furthermore, fibronectin, collagen I, and collagen IV disrupted interactions of AGO2 and DROSHA with their essential partners GW182 and DGCR8, respectively, both at AJs and throughout the cell. Combinations of all substrates with fibronectin also negatively impacted junctional localization of PLEKHA7 and AGO2. Additionally, collagen I triggered accumulation of DROSHA at tri-cellular junctions, while both collagen I and collagen IV resulted in DROSHA accumulation at basal areas of cell-cell contact. Altogether, fibronectin and collagens I and IV, which are elevated in the stroma of fibrotic and cancerous tissues, altered localization patterns and disrupted complex formation of PLEKHA7 and RNAi components. Combined with our prior studies showing that apical junctional localization of the PLEKHA7-RNAi complex is critical for regulating tumor-suppressing miRNAs, this work points to a yet unstudied mechanism that could contribute to epithelial cell transformation. Adherens junction ; Cell biology ; RNA interference ; Chemistry ; Biology ; Cadherin ; Cell ; Gene ; Biochemistry ; RNA Magnesium Alloys: Properties and Applications ; RNA Interference and Gene Delivery ; MicroRNA in disease regulation
Authors: Pedro Carreira | Daniel Gatões | Nuno Alves | Ana Sofia Ramos | M.T. Vieira
Source: Materials (article, 2022-07-19)
Field: Materials Science — Materials Chemistry

Searching New Solutions for NiTi Sensors through Indirect Additive Manufacturing Shape Memory Alloys (SMAs) can play an essential role in developing novel active sensors for self-healing, including aeronautical systems. However, the NiTi SMAs available in the market are almost limited to wires, small sheets, and coatings. This restriction is mainly due to the difficulty in processing NiTi through conventional processes. Thus, the objective of this study is to evaluate the potential of one of the most promising routes for NiTi additive manufacturing-material extrusion (MEX). Optimizing the different steps during processing is mandatory to avoid brittle secondary phases formation, such as Ni<sub>3</sub>Ti. The prime NiTi powder is prealloyed, but it also contains NiTi<sub>2</sub> and Ni as secondary phases. The present study highlights the role of Ni and NiTi<sub>2</sub>, with the later having a melting temperature (Tm = 984 °C) lower than the NiTi sintering temperature, thus allowing a welcome liquid phase sintering (LPS). Nevertheless, the reaction of the liquid phase with the Ni phase could contribute to the formation of brittle intermetallic compounds, particularly around NiTi and NiTi<sub>2</sub> phases, affecting the final structural properties of the 3D object. The addition of TiH<sub>2</sub> to the virgin prealloyed NiTi powder was also studied and revealed the non-formation of Ni<sub>3</sub>Ti for a specific composition. The balancing addition of extra Ni revealed priority in the Ni<sub>3</sub>Ti appearance, emphasizing the role of Ni. Feedstocks extruded (filaments) and green strands (layers), before and after debinding & sintering, were used as homothetic of 3D objects for evaluation of defects (microtomography), microstructures, and mechanical properties. The composition of prealloyed powder with 5 wt.% TiH<sub>2</sub> addition after sintering showed a homogeneous matrix with the NiTi<sub>2</sub> second phase uniformly dispersed. Nickel titanium ; Materials science ; Process engineering ; Metallurgy ; Shape-memory alloy ; Engineering Shape Memory Alloy Transformations ; Additive Manufacturing Materials and Processes ; Material Selection and Properties
Authors: Y. Urade | Kai Fukawa | Fumiaki Miyamaru | Kunio Okimura | Toshihiro Nakanishi | Yosuke Nakata
Source: Nanophotonics (article, 2022-01-10)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Dynamic inversion of planar‐chiral response of terahertz metasurface based on critical transition of checkerboard structures Dynamic inversion of the planar-chiral responses of a metasurface is experimentally demonstrated in the terahertz regime. To realize this inversion, the critical transition of the checkerboard-like metallic structures is used. Resonant structures with planar chirality and their complementary enantiomeric patterns are embedded in the checkerboard. Using vanadium dioxide as a variable resistance, the metasurface is implemented in the terahertz regime. The responses of the metasurface to circularly polarized waves are then characterized by terahertz time-domain spectroscopy. Further, the sign of the circular conversion dichroism, which is closely related to the handedness of the planar chirality of the metasurface, is observed to be inverted at 0.64 THz by varying the temperature. Such invertible planar-chiral responses can be applied practically to the handedness-invertible chiral mirrors. Checkerboard ; Planar ; Terahertz radiation ; Metamaterial ; Materials science ; Inversion (geology) ; Nanomaterials ; Optics ; Optoelectronics ; Nanotechnology ; Physics ; Computer science ; Mathematics ; Geometry ; Geology Metamaterials and Metasurfaces Applications ; Terahertz technology and applications ; Antenna Design and Analysis
Authors: Andrea Schirato | Andréa Toma | Remo Proietti Zaccaria | Alessandro Alabastri | Giulio Cerullo | Giuseppe Della Valle | Margherita Maiuri
Source: Advanced Optical Materials (article, 2022-03-23)
Field: Materials Science — Electronic, Optical and Magnetic Materials

All‐Optical Reconfiguration of Ultrafast Dichroism in Gold Metasurfaces Abstract Optical metasurfaces have come into the spotlight as a promising platform for light manipulation at the nanoscale, including ultrafast all‐optical control via excitation with femtosecond laser pulses. Recently, dichroic metasurfaces have been exploited to modulate the polarization state of light with unprecedented speed. This work theoretically predicts and experimentally demonstrates by pump–probe spectroscopy the capability to reconfigure the ultrafast dichroic signal of a gold metasurface by simply acting on the polarization of the pump pulse, which is shown to reshape the spatio‐temporal distribution of the optical perturbation. The photoinduced anisotropic response, driven by out‐of‐equilibrium carriers and extinguished in a sub‐picosecond temporal window, is readily controlled in intensity by tuning the polarization direction of the excitation up to a full sign reversal. Hence, nonlinear metasurfaces are here demonstrated to offer the flexibility to tailor their ultrafast optical response in a fully all‐optically reconfigurable platform. Ultrashort pulse ; Dichroic glass ; Femtosecond ; Materials science ; Picosecond ; Optics ; Polarization (electrochemistry) ; Optoelectronics ; Dichroism ; Dichroic filter ; Excitation ; Photonics ; Laser ; Physics ; Wavelength Metamaterials and Metasurfaces Applications ; Plasmonic and Surface Plasmon Research ; Orbital Angular Momentum in Optics
Authors: Long Chen | Qingbao Yang | Xue Yang | Zhanqiang Liu | Qinghua Song
Source: Nanotechnology Reviews (article, 2022-01-01)
Field: Materials Science — Polymers and Plastics

An investigation on thermo-mechanical performance of graphene-oxide-reinforced shape memory polymer Abstract Based on micro morphology, a thermo-mechanical coupling model of shape memory graphene oxide/epoxy resin (SMGO/EP) was proposed. The heat transfer capability, mechanical property and shape memory ability of shape memory polymer (SMP) were further investigated. The reliability of the modeling was verified by comparing the heat transfer and shape fixation rate of the experimental and simulation data. The results showed that the maximum error of heat transfer was 6.04%, and shape fixing rate error was 2.33%. When the volume fraction of GO was 1.50 vol%, the maximum stress can reach 158.39 MPa, 46.52% higher than that of pure shape memory EP. With the increase in the volume fraction of GO in the SMGO/EP composites, the heat transfer enhancement and recovery rate of SMGO/EP were directly affected by the doping content of GO. The surface temperature of the composites with GO doping content of 1.50 vol% was 20.26°C higher than that of pure SMEP after heating for 300 s. Under the coupling effect of heat transfer and stress characteristics, the mechanism of shape memory effect of SMGO/EP composites was revealed. The thermo-mechanical coupling modeling of SMGO/EP can effectively predict the shape memory characteristics of the SMGO/EP composites. Materials science ; Composite material ; Volume fraction ; Shape-memory alloy ; Graphene ; Oxide ; Heat transfer ; Coupling (piping) ; Epoxy ; Shape-memory polymer ; Polymer ; Doping ; Stress (linguistics) ; Nanotechnology ; Thermodynamics Polymer composites and self-healing ; Photochromic and Fluorescence Chemistry ; Conducting polymers and applications