jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Emanuele Lago | Péter S. Tóth | Silvia Gentiluomo | Sanjay Thorat | Vittorio Pellegrini | Francesco Bonaccorso
Source: Journal of Physics Materials (article, 2021-06-11)
Field: Materials Science — Materials Chemistry

Dependence of the polycarbonate mechanical performances on boron nitride flakes morphology Abstract A key requirement for the exploitation of two-dimensional (2D)-crystals in the field of composites relies on their large-scale production. In this respect, liquid phase exfoliation of layered-crystals is emerging as one of the most promising approaches for the scalable production of high-quality 2D-crystals. However, the dependence of the 2D crystal flakes morphology, i.e. thickness and lateral size, on the mechanical properties of the polymer composites is not fully understood yet. Herein, we tackle this issue by designing an environmentally friendly approach, based on the exfoliation of bulk hexagonal-boron nitride ( h -BN), widely used as filler in polymer composites for its high intrinsic stiffness, i.e. approaching 1 TPa, in a water/surfactant solution with controlled thickness and lateral size by using cascade ultra-centrifugation. Our approach allows us to obtain two populations of flakes with aspect ratio, i.e. lateral size over thickness, equal to 250 and 350, respectively. The h -BN flakes with tuned aspect ratio are subsequently used as filler in a polycarbonate (PC) matrix by exploiting solution blending in 1,3-dioxolane, a solvent with Hansen’s solubility parameters matching the ones of h -BN, thus enhancing the dispersion of the filler inside the matrix, as evaluated by Raman mapping. We tested the composite mechanical properties finding that flakes with higher aspect ratio show superior reinforcements in terms of both ultimate tensile strength and Young’s modulus, compared with their lower aspect ratio counterparts. As example, at 0.1 wt% of loading, the difference in reinforcement in terms of Young’s Modulus is of 56 MPa, being the increment, compared to pristine PC, of ∼22% for composites produced with higher aspect ratio fillers, whereas it is instead of only ∼17% for lower aspect ratio fillers. Materials science ; Composite material ; Exfoliation joint ; Boron nitride ; Ultimate tensile strength ; Polycarbonate ; Aspect ratio (aeronautics) ; Composite number ; Polymer ; Nanotechnology ; Graphene Graphene research and applications ; Advanced Sensor and Energy Harvesting Materials ; Thermal properties of materials
Authors: Sam Rajan | Arun Kumar | Jayakumari Isac
Source: Processing and Application of Ceramics (article, 2021-01-01)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Colossal magnetoresistance of Nd-doped LaCaMnO3 polycrystalline ceramics The cation doped polycrystalline compound La0.5Nd0.15Ca0.35MnO3 has been synthesized by a conventional solid state reaction method. The Rietveld analysis of the powder XRD of the composites reveals an orthorhombic structure with Pbnm space group symmetry. The cell parameters are a = 5.4505 ?, b = 5.4457 ? and c = 7.6876?. The AC magnetization studies show a semiconducting paramagnetic to metallic ferromagnetic transition at a temperature below the Curie temperature TC which is found to be 206.3K. It is also observed that metal to semiconductor transition temperature TMS is very close to TC. The sample also possesses high magnetoresistance, which is revealed in MR studies. Materials science ; Magnetoresistance ; Rietveld refinement ; Orthorhombic crystal system ; Magnetization ; Crystallite ; Colossal magnetoresistance ; Condensed matter physics ; Ferromagnetism ; Curie temperature ; Paramagnetism ; Crystallography ; Crystal structure ; Metallurgy ; Magnetic field ; Chemistry Magnetic and transport properties of perovskites and related materials
Authors: Claudia S. Cox | Valeria Cossich Galicia | Martina Lessio
Source: Australian Journal of Chemistry (article, 2021-09-02)
Field: Chemistry — Inorganic Chemistry

Computational Investigation of Adsorptive Removal of Pb2+ from Water by the UiO-66 Metal–Organic Framework: Comparison of Adsorption Sites on Defects and Functionalised Linkers Adsorption using metal–organic frameworks (MOFs) such as UiO-66 has shown great promise in remediating water sources contaminated with toxic heavy metals such as Pb2+, but detailed information about the adsorption process remains limited. In this article, we gained mechanistic insights into Pb2+ adsorption using both functionalised and defective UiO-66 by performing density functional theory calculations using cluster models. Our benchmarked approach led to a computational model of solvated Pb2+ (a hemidirected Pb(H2O)62+ complex) fully consistent with experimental reports. The analysis of Pb2+ adsorption using functionalised UiO-66 determined that factors such as electrostatic attraction, chelation, and limited constraints on the Pb2+ coordination geometry lead to enhanced binding affinity. For these reasons, UiO-66-COO– was identified as the most promising functionalised MOF, consistent with experimental literature. We additionally explored a novel aspect of Pb2+ adsorption by UiO-66: the role of missing linker defects that often characterise this MOF. We found that the defects expected to form in an aqueous environment can act as excellent adsorption sites for Pb2+ and the preferred adsorption geometry is again determined by electrostatic attraction, chelation, and constraints on the Pb2+ coordination geometry. Overall, we conclude that functional groups and defect sites can both contribute to Pb2+ adsorption and our study provides crucial design principles for improving the UiO-66 MOF performance in toxic Pb2+ removal from water. Adsorption ; Density functional theory ; Chemistry ; Metal-organic framework ; Aqueous solution ; Chelation ; Cluster (spacecraft) ; Computational chemistry ; Linker ; Metal ions in aqueous solution ; Metal ; Inorganic chemistry ; Physical chemistry ; Organic chemistry ; Computer science Metal-Organic Frameworks: Synthesis and Applications ; X-ray Diffraction in Crystallography ; Radioactive element chemistry and processing
Authors: Paulina Valencia-Gálvez | Daniela Delgado | Marı́a Luisa López | Inmaculada Álvarez-Serrano | Silvana Moris | Antonio Galdámez
Source: Crystals (article, 2021-07-26)
Field: Materials Science — Materials Chemistry

AgSn[Bi1−xSbx]Se3: Synthesis, Structural Characterization, and Electrical Behavior Herein, we report the synthesis, characterization, and electrical properties of lead-free AgSnm[Bi1−xSbx]Se2+m (m = 1, 2) selenides. Powder X-ray diffraction patterns and Rietveld refinement data revealed that these selenides consisted of phases related to NaCl-type crystal structure. The microstructures and morphologies of the selenides were investigated by backscattered scanning electron microscopy, energy-dispersive X-ray spectroscopy, and high-resolution transmission electron microscopy. The studied AgSnm[Bi1−xSbx]Se2+m systems exhibited typical p-type semiconductor behavior with a carrier concentration of approximately ~+1020 cm−3. The electrical conductivity of AgSnm[Bi1−xSbx]Se2+m decreased from ~3.0 to ~10−3 S·cm−1 at room temperature (RT) with an increase in m from 1 to 2, and the Seebeck coefficient increased almost linearly with increasing temperature. Furthermore, the Seebeck coefficient of AgSn[Bi1−xSbx]Se3 increased from ~+36 to +50 μV·K−1 with increasing Sb content (x) at RT, while its average value determined for AgSn2[Bi1−xSbx]Se4 was approximately ~+4.5 μV·K−1. Seebeck coefficient ; Electrical resistivity and conductivity ; Materials science ; High-resolution transmission electron microscopy ; Scanning electron microscope ; Thermoelectric effect ; Analytical Chemistry (journal) ; Microstructure ; Rietveld refinement ; Transmission electron microscopy ; Semiconductor ; Thermoelectric materials ; Powder diffraction ; Crystal structure ; Crystallography ; Chemistry ; Nanotechnology ; Metallurgy ; Thermal conductivity ; Optoelectronics ; Composite material ; Electrical engineering Advanced Thermoelectric Materials and Devices ; Chalcogenide Semiconductor Thin Films ; Heusler alloys: electronic and magnetic properties
Authors: Xin Chen | Cian Bartlam | Vicent Lloret | Narine Moses Badlyan | Stefan Wolff | Roland Gillen | Tanja Stimpel‐Lindner | Janina Maultzsch | Georg S. Duesberg | Kathrin C. Knirsch | Andreas Hirsch
Source: Angewandte Chemie (article, 2021-03-26)
Field: Materials Science — Materials Chemistry

Covalent Bisfunctionalization of Two‐Dimensional Molybdenum Disulfide Abstract Covalent functionalization of two‐dimensional molybdenum disulfide (2D MoS 2 ) holds great promise in developing robust organic‐MoS 2 hybrid structures. Herein, for the first time, we demonstrate an approach to building up a bisfunctionalized MoS 2 hybrid structure through successively reacting activated MoS 2 with alkyl iodide and aryl diazonium salts. This approach can be utilized to modify both colloidal and substrate supported MoS 2 nanosheets. We have discovered that compared to the adducts formed through the reactions of MoS 2 with diazonium salts, those formed through the reactions of MoS 2 with alkyl iodides display higher reactivity towards further reactions with electrophiles. We are convinced that our systematic study on the formation and reactivity of covalently functionalized MoS 2 hybrids will provide some practical guidance on multi‐angle tailoring of the properties of 2D MoS 2 for various potential applications. Covalent bond ; Alkyl ; Electrophile ; Molybdenum disulfide ; Reactivity (psychology) ; Chemistry ; Surface modification ; Aryl ; Adduct ; Molybdenum ; Combinatorial chemistry ; Iodide ; Substrate (aquarium) ; Hybrid material ; Polymer chemistry ; Materials science ; Organic chemistry ; Catalysis ; Physical chemistry 2D Materials and Applications ; Covalent Organic Framework Applications ; MXene and MAX Phase Materials
Authors: Victor Krivenkov | Pavel Samokhvalov | И. С. Васильевский | Nikolai I. Kargin | Igor Nabiev
Source: Nanoscale (article, 2021-01-01)
Field: Materials Science — Materials Chemistry

Plasmon–exciton interaction strongly increases the efficiency of a quantum dot-based near-infrared photodetector operating in the two-photon absorption mode under normal conditions Semiconductor quantum dots (QDs) are known for their high two-photon absorption (TPA) capacity. This allows them to efficiently absorb infrared photons with energies lower than the bandgap energy. Moreover, TPA in QDs can be further enhanced by the interaction of excitons of the QDs with plasmons of a metal nanoparticle. We fabricated nonlinear plasmon-exciton photodetectors based on QDs and silver nanoplates (SNPs) to demonstrate the optoelectronic application of these effects. A thin layer of CdSe QDs was used as a source of charge carriers for a photoresistor-type photodetector. SNPs with near-infrared plasmon modes were introduced into the layer of QDs to increase the light absorption efficiency. Under near-infrared irradiation, the power of the dependence of the photocurrent on the excitation intensity was twice the power of the corresponding dependence under one-photon excitation with visible light. This proved that the new photodetector efficiently operated under two-photon excitation. Although the SNP light absorption was linear, energy was transferred from plasmons to excitons in the two-quantum mode, which led to a nonlinear dependence. Moreover, we found that the photocurrent from the designed photodetector containing the QD-SNP composite was an order of magnitude higher than that from a photodetector containing QDs alone. This can be explained by the plasmon-induced increase in the TPA efficiency. Photodetector ; Photon ; Quantum dot ; Plasmon ; Optoelectronics ; Infrared ; Exciton ; Absorption (acoustics) ; Materials science ; Optics ; Physics ; Condensed matter physics Quantum Dots Synthesis And Properties ; Photonic and Optical Devices ; Nonlinear Optical Materials Studies
Authors: Zheng Shi | Hai-Zhou Lu | Tianyu Liu
Source: Physical Review Research (article, 2021-08-11)
Field: Materials Science — Materials Chemistry

Pseudo Landau levels, negative strain resistivity, and enhanced thermopower in twisted graphene nanoribbons As a canonical response to the applied magnetic field, the electronic states of a metal are fundamentally reorganized into Landau levels. In Dirac metals, Landau levels can be expected without magnetic fields, provided that an inhomogeneous strain is applied to spatially modulate electron hoppings in a way similar to the Aharonov-Bohm phase. We here predict that a twisted zigzag nanoribbon of graphene exhibits strain-induced pseudo Landau levels of unexplored but analytically solvable dispersions at low energies. The presence of such dispersive pseudo Landau levels results in a negative strain resistivity characterizing the ($1+1$)-dimensional chiral anomaly if partially filled and can greatly enhance the thermopower when fully filled. Zigzag ; Seebeck coefficient ; Landau quantization ; Graphene ; Strain (injury) ; Magnetoresistance ; Anomaly (physics) Graphene research and applications ; Topological Materials and Phenomena ; 2D Materials and Applications
Authors: Pilar Gómez-Rodríguez | Esther Soria | Jin Yu | A. Caño | I. Llorente | Alexander Cuadrado | A. Mariscal | A. K. Petford‐Long | R. Serna | J. Gonzalo
Source: Nanophotonics (article, 2021-10-16)
Field: Materials Science — Materials Chemistry

Toward white light emission from plasmonic‐luminescent hybrid nanostructures Abstract We study the light emission of plasmonic‐luminescent hybrid nanostructures consisting of Ag nanoparticles (NPs) embedded in europium oxide (EuO X ). The Ag NPs present a bidimensional organization in the nanostructures and they optically behave as oblate spheroids. The photoluminescence (PL) spectral response of the nanostructures evolves from a narrow red emission characteristic of Eu 3+ ions in absence of Ag NPs to a broad blue‐green emission band associated with Eu 2+ ions when the layer of Ag NPs is present. This behavior is not related to a change in the Eu 2+ /Eu 3+ ratio, which is verified by compositional analysis. Instead, a detailed investigation of the PL emission of the nanostructures suggests that the coupling of the Ag NPs to the Eu 2+ ions present in the EuO X layer, which manifests itself in an efficient sensitization of these ions, enhances their broad visible emission. In particular, the longitudinal mode of the Ag NPs surface plasmon is considered to be responsible for the efficient energy transfer for the non‐normal incidence excitation PL configuration used. Finally, the use of a capping amorphous Al 2 O 3 layer allows improving the robustness of hybrid nanostructures and further enhances their PL emission. These findings provide a new path to actively control the selective excitation of Eu 2+ and Eu 3+ ions via a controlled coupling with the surface plasmon resonance modes of the Ag NPs and points to these nanostructures as promising building blocks for the development of integrable white light sources. Materials science ; Photoluminescence ; Luminescence ; Nanostructure ; Surface plasmon resonance ; Europium ; Plasmon ; Ion ; Optoelectronics ; Amorphous solid ; Nanoparticle ; Surface plasmon ; Nanotechnology ; Chemistry ; Crystallography Nanocluster Synthesis and Applications ; Gold and Silver Nanoparticles Synthesis and Applications ; Luminescence Properties of Advanced Materials
Authors: Toshinori Ozaki | Takuya Kashihara | Itsuhiro Kakeya | Ryoya Ishigami
Source: Quantum Beam Science (article, 2021-06-04)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Effect of 1.5 MeV Proton Irradiation on Superconductivity in FeSe0.5Te0.5 Thin Films Raising the critical current density Jc in magnetic fields is crucial to applications such as rotation machines, generators for wind turbines and magnet use in medical imaging machines. The increase in Jc has been achieved by introducing structural defects including precipitates and vacancies. Recently, a low-energy ion irradiation has been revisited as a practically feasible approach to create nanoscale defects, resulting in an increase in Jc in magnetic fields. In this paper, we report the effect of proton irradiation with 1.5 MeV on superconducting properties of iron–chalcogenide FeSe0.5Te0.5 films through the transport and magnetization measurements. The 1.5 MeV proton irradiation with 1 × 1016 p/cm2 yields the highest Jc increase, approximately 30% at 5–10 K and below 1 T without any reduction in Tc. These results indicate that 1.5 MeV proton irradiations could be a practical tool to enhance the performance of iron-based superconducting tapes under magnetic fields. Materials science ; Irradiation ; Chalcogenide ; Proton ; Superconductivity ; Condensed matter physics ; Magnet ; Magnetization ; Magnetic field ; Nuclear physics ; Optoelectronics ; Physics Iron-based superconductors research ; Physics of Superconductivity and Magnetism ; Rare-earth and actinide compounds
Authors: Teija Laukala | Sami-Seppo Ovaska | Ninja Kerttula | Kaj Backfolk
Source: Cellulose (article, 2021-08-25)
Field: Materials Science — Biomaterials

Three-dimensional thermomechanical converting of CTMP substrates: effect of bio-based strengthening agents and new mineral filling concept Abstract The effects of bio-based strengthening agents and mineral filling procedure on the 3D elongation of chemi-thermomechanical pulp (CTMP) handsheets with and without mineral (PCC) filling have been investigated. The 3D elongation was measured using a press-forming machine equipped with a special converting tool. The strength of the handsheets was altered using either cationic starch or microfibrillated cellulose. Precipitated calcium carbonate (PCC) was added to the furnish either as a slurry or by precipitation of nano-sized PCC onto and into the CTMP fibre. The 3D elongation of unfilled sheets was increased by the dry-strengthening agents, but no evidence on the theorised positive effect of mineral fill on 3D elongation was seen in either filling method. The performance of the strengthening agent depended on whether the PCC was as slurry or as a precipitated PCC-CTMP. The starch was more effective with PCC-CTMP than when the PCC was added directly as a slurry to the furnish, whereas the opposite was observed with microfibrillated cellulose. The 3D elongation correlated positively with the tensile strength, bursting strength, tensile stiffness, elastic modulus and bending stiffness, even when the sheet composition was varied, but neither the strengthening agent nor the method of PCC addition affected the 3D elongation beyond what was expectable based on the tensile strength of the sheets. Finally, mechanisms affecting the properties that correlated with the 3D elongation are discussed. Elongation ; Ultimate tensile strength ; Materials science ; Slurry ; Composite material ; Cellulose ; Starch ; Young's modulus ; Chemical engineering ; Chemistry Advanced Cellulose Research Studies ; Polysaccharides Composition and Applications ; Nanocomposite Films for Food Packaging
Authors: Giulio Giovannetti | Alessandra Flori | Maria Filomena Santarelli | Vincenzo Positano | Nicola Martini | Roberto Francischello | Rolf F. Schulte | Jan Henrik Ardenkjær‐Larsen | Luca Menichetti | Giovanni Donato Aquaro | Andrea Barison | Francesca Frijia
Source: Electronics (article, 2021-02-03)
Field: Chemistry — Spectroscopy

Radio Frequency Coils for Hyperpolarized 13C Magnetic Resonance Experiments with a 3T MR Clinical Scanner: Experience from a Cardiovascular Lab Hyperpolarized 13C magnetic resonance (MR) is a promising technique for the noninvasive assessment of the regional cardiac metabolism since it permits heart physiology studies in pig and mouse models. The main objective of the present study is to resume the work carried out at our electromagnetic laboratory in the field of radio frequency (RF) coil design, building, and testing. In this paper, first, we review the principles of RF coils, coil performance parameters, and estimation methods by using simulations, workbench, and MR imaging experiments. Then, we describe the simulation, design, and testing of different 13C coil configurations and acquisition settings for hyperpolarized studies on pig and mouse heart with a clinical 3T MRI scanner. The coil simulation is performed by developing a signal-to-noise ratio (SNR) model in terms of coil resistance, sample-induced resistance, and magnetic field pattern. Coil resistance was calculated from Ohm’s law and sample-induced resistances were estimated with a finite-difference time-domain (FDTD) algorithm. In contrast, the magnetic field per unit current was calculated by magnetostatic theory and a FDTD algorithm. The information could be of interest to graduate students and researchers working on the design and development of an MR coil to be used in 13C studies. Electromagnetic coil ; Ohm ; Finite-difference time-domain method ; Radiofrequency coil ; Scanner ; Nuclear magnetic resonance ; Magnetic resonance imaging ; Radio frequency ; Magnetic field ; Computer science ; Physics ; Acoustics ; Biomedical engineering ; Engineering ; Electrical engineering ; Medicine ; Telecommunications ; Optics ; Radiology Advanced NMR Techniques and Applications ; Advanced MRI Techniques and Applications ; NMR spectroscopy and applications
Authors: Vidhyadhar Manee | Roberto Baratti | José A. Romagnoli
Source: UNICA IRIS Institutional Research Information System (University of Cagliari) (article, 2021-01-01)
Field: Materials Science — Materials Chemistry

Optimal Strategies to Control Particle Size and Variance in Antisolvent Crystallization Operations Using Deep Rl Solution crystallization operations have complex dynamics that are typically lumped into two competing processes namely nucleation and growth. Mathematical models can be used to describe these two processes and their effect on the crystal population when subject to variables like temperature, addition of anti-solvent, etc. To ensure that the crystals meet specific performance objectives, the models need to be solved and the control variables need to be optimized. This has largely been done until now using algorithms from dynamic programming or optimal control theory. Recently, however, it has been shown that learning frameworks like Reinforcement Learning can solve large optimization problems efficiently while offering distinct advantages. In this work, we explore the possibility of computing the optimal profiles of a semi-batch crystallizer to control the mean size and variance using four different deep RL algorithms. The performance on one of the tasks is evaluated experimentally on the anti-solvent crystallization of NaCl in a water-ethanol system. Crystallization ; Variance (accounting) ; Particle size ; Particle (ecology) ; Control (management) ; Computer science ; Materials science ; Mathematics ; Statistics ; Artificial intelligence ; Chemical engineering ; Engineering ; Business ; Biology Crystallization and Solubility Studies