jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Junfeng Qiao | Giovanni Pizzi | Nicola Marzari
Source: Research Square (preprint, 2023-03-22)
Field: Materials Science — Materials Chemistry

Projectability disentanglement for accurate and automated electronic-structure Hamiltonians Abstract Maximally-localized Wannier functions (MLWFs) are a powerful and broadly used tool to characterize the electronic structure of materials, from chemical bonding to dielectric response to topological properties. Most generally, one can construct MLWFs that describe isolated band manifolds, e.g. for the valence bands of insulators, or entangled band manifolds, e.g. in metals or describing both the valence and the conduction manifolds in insulators. Obtaining MLWFs that describe a target manifold accurately and with the most compact representation often requires chemical intuition and trial and error, a challenging step even for experienced researchers and a roadblock for automated high-throughput calculations. Here, we present a very natural and powerful approach that provides automatically MLWFs spanning the occupied bands and their natural complement for the empty states, resulting in Wannier Hamiltonian models that provide a tight-binding picture of optimized atomic orbitals in crystals. Key to the success of the algorithm is the introduction of a projectability measure for each Bloch state onto atomic orbitals (here, chosen from the pseudopotential projectors) that determines if that state should be kept identically, discarded, or mixed into a disentangling algorithm. We showcase the accuracy of our method by comparing a reference test set of 200 materials against the selected-columns-of-the-density-matrix algorithm, and its reliability by constructing Wannier Hamiltonians for 21737 materials from the Materials Cloud. Statistical physics ; Electronic structure ; Physics ; Computer science ; Condensed matter physics Machine Learning in Materials Science ; Advancements in Photolithography Techniques ; Semiconductor materials and devices
Authors: N.N. Eliseev | A. A. Nevzorov | V. A. Mikhalevsky | А. В. Киселев | А.А. Бурцев | V. V. Ionin | А. А. Лотин
Source: Scientific and technical journal of information technologies mechanics and optics (article, 2023-10-01)
Field: Materials Science — Materials Chemistry

Switching the electrical properties of thin-film memristive elements based on GeTe by sequences of ultrashort laser pulses The work is devoted to the study of the characteristics of the state control of a thin-film element based on a phase-change GeTe material. The properties of such an element have been controlled by the action of sequences of ultrashort laser pulses. This action leads to a rapid heating of the thin film element and provides a phase transition between states with a resistance different by several orders of magnitude. The dynamics of the resistance was studied using a high speed oscilloscope according to the scheme where the element under study was the voltage divider arm of a highly stable source. Three different types of conductivity switching were observed for 100 nm thin films. For low energy laser radiation, several distinct states were obtained in which the material film has predominantly semiconducting properties. As the energy of the optical pulses increases, the number of possible stable states determined by the specific conductivity of the material decreases to two, one of which (low resistance) is exclusively metallic properties. In all cases, the time taken to switch to a stable state does not exceed a few tens of nanoseconds for films up to 100 nm thick. The study has demonstrated that the structures described can be used to implement optically controlled memristive elements. In addition, the large number of possible allowable specific resistances of the element will make it possible to use it to increase the information capacity of memory cells based on phase-change materials or to implement optoelectronic neuromorphic systems. Materials science ; Laser ; Thin film ; Optoelectronics ; Electrical element ; Phase (matter) ; Conductivity ; Nanosecond ; Phase transition ; Voltage ; Optics ; Nanotechnology ; Condensed matter physics ; Electrical engineering ; Physics Phase-change materials and chalcogenides ; Photoreceptor and optogenetics research ; Nonlinear Dynamics and Pattern Formation
Authors: Shannon S. Nicley | Gavin W. Morley | Ken Haenen
Source: Philosophical Transactions of the Royal Society A Mathematical Physical and Engineering Sciences (article, 2023-12-04)
Field: Materials Science — Materials Chemistry

A special issue preface: diamond for quantum applications This special issue discusses current progress in the utilization of defect centres in diamond as spin-photon interfaces for quantum applications. This issue is based on the discussions of the Theo Murphy meeting 'Diamond for quantum applications' which covered the recent progress of diamond growth and engineering for the creation and optimization of colour centres, toward the integration of diamond-based qubits in quantum systems. This article is part of the Theo Murphy meeting issue 'Diamond for quantum applications'. Diamond ; Quantum ; Qubit ; Engineering physics ; Quantum technology ; Nanotechnology ; Computer science ; Physics ; Quantum mechanics ; Materials science ; Open quantum system Diamond and Carbon-based Materials Research ; Electronic and Structural Properties of Oxides ; High-pressure geophysics and materials
Authors: Michaël Lobet | Nathaniel Kinsey | Iñigo Liberal | Hümeyra Çağlayan | Paloma A. Huidobro | Emanuele Galiffi | J. R. Mejía-Salazar | Giovanna Palermo | Zubin Jacob | Nicolò Maccaferri
Source: arXiv (Cornell University) (preprint, 2023-06-02)
Field: Materials Science — Electronic, Optical and Magnetic Materials

New horizons in near-zero refractive index photonics and hyperbolic metamaterials The engineering of the spatial and temporal properties of both the electric permittivity and the refractive index of materials is at the core of photonics. When vanishing to zero, those two variables provide new knobs to control light-matter interactions. This perspective aims at providing an overview of the state of the art and the challenges in emerging research areas where the use of near-zero refractive index and hyperbolic metamaterials is pivotal, in particular light and thermal emission, nonlinear optics, sensing applications and time-varying photonics. Photonics ; Metamaterial ; Refractive index ; Photonic metamaterial ; Transformation optics ; Permittivity ; Optics ; Index (typography) ; Physics ; Optoelectronics ; Computer science ; Dielectric Metamaterials and Metasurfaces Applications ; Thermal Radiation and Cooling Technologies ; Plasmonic and Surface Plasmon Research
Authors: N. D. Andriushin | A. S. Sukhanov | A. N. Korshunov | M. S. Pavlovskiĭ | M. C. Rahn | С. Е. Никитин
Source: Physical Review Letters (article, 2023-12-14)
Field: Materials Science — Materials Chemistry

Phonon Topology and Winding of Spectral Weight in Graphite The topology of electronic and phonon band structures of graphene is well studied and known to exhibit a Dirac cone at the $K$ point of the Brillouin zone. Here, we applied inelastic x-ray scattering (IXS) along with ab initio calculations to investigate phonon topology in graphite, the 3D analog of graphene. We identified a pair of modes that form a very weakly gapped linear anticrossing at the $K$ point that can be essentially viewed as a Dirac cone approximant. The IXS intensity in the vicinity of the quasi-Dirac point reveals a harmonic modulation of the phonon spectral weight above and below the Dirac energy, which was previously proposed as an experimental fingerprint of the nontrivial topology. We illustrate how the topological winding of IXS intensity can be understood in terms of atomic displacements and highlight that the intensity winding is not in fact sensitive in telling quasi- and true Dirac points apart. Graphite ; Phonon ; Topology (electrical circuits) ; Materials science ; Condensed matter physics ; Physics ; Composite material ; Mathematics ; Combinatorics Graphene research and applications ; Topological Materials and Phenomena ; Thermal properties of materials
Authors: Mirco Scaccaglia | Giorgio Pelosi | Silvana Pienlli | Angelo Frei
Source: ChemRxiv (preprint, 2023-09-05)
Field: Chemistry — Inorganic Chemistry

Discovery of Antibacterial Manganese(I) Tricarbonyl Complexes through Combinatorial Chemistry The continuous rise of antimicrobial resistance is a serious threat to human health and already causing hundreds of thousands of deaths each year. While natural products and synthetic organic small molecules have provided the majority of our current antibiotic arsenal, they are falling short in providing new drugs with novel modes of action able to treat multidrug resistant bacteria. Metal complexes have recently shown promising results as antimicrobial agents, but the number of studied compounds is still vanishingly small, making it difficult to identify promising compound classes or elucidate structure-activity relationships. To accelerate the pace of discovery we have applied a combinatorial chemistry approach to the synthesis of metalloantibiotics. Utilizing robust Schiff-base chemistry and combining 7 picolinaldehydes with 10 aniline derivatives, and 5 axial ligands we have prepared a library of 420 novel manganese tricarbonyl complexes. All compounds were evaluated for their antibacterial properties and 10 lead compounds were identified, re-synthesized and fully characterized. All 10 compounds showed high and broad activity against Gram-positive bacteria. The best manganese complex displayed low toxicity against human cells with a therapeutic index of >100. In initial mode of action studies, we show that it targets the bacterial membrane without inducing pore formation or depolarisation. Instead, it releases its carbon monoxide ligands around the membrane and inhibits the bacterial respiratory chain. This work demonstrates that large numbers of metal complexes can be accessed through combinatorial synthesis and evaluated for their antibacterial potential, allowing for the rapid identification of promising metalloantibiotic lead compounds. Combinatorial chemistry ; Chemistry ; Antimicrobial ; Antibacterial activity ; Manganese ; Aniline ; Bacteria ; Organic chemistry ; Biology Metal-Catalyzed Oxygenation Mechanisms ; Microbial Natural Products and Biosynthesis ; Metal complexes synthesis and properties
Authors: Yash Pachaury | G. F. Warren | Janelle P. Wharry | Giacomo Po | Anter El‐Azab
Source: arXiv (Cornell University) (preprint, 2023-01-04)
Field: Materials Science — Materials Chemistry

Plasticity in irradiated FeCrAl nanopillars investigated using discrete dislocation dynamics In this paper, we investigate plasticity in irradiated FeCrAl nanopillars using discrete dislocation dynamics simulations (DDD), with comparisons to transmission electron microscopic (TEM) in situ tensile tests of ion and neutron irradiated commercial FeCrAl alloy C35M. The effects of irradiation-induced defects, such as a/2 111 and a 100 type loops and composition fluctuations representative of phase separation in irradiated FeCrAl alloys, are investigated separately as well as superposed together in simulations. We explore the effects of defects on the stress-strain behavior, specifically yield strength and hardening response, of FeCrAl nanopillars. Our simulations confirm the widely accepted fact that irradiated alloys exhibit a stress-strain response with higher yield strength and hardening as compared to homogeneous alloys. However, our DDD calculations reveal an atypical superposition of the hardening contributions due to composition inhomogeneity and irradiation loops wherein hardening due composition inhomogeneity counteracts hardening due to irradiation loops at small scales. As a result, we observe that the yield strength in irradiated alloys, after taking into consideration the effects of both composition inhomogeneity and irradiation loops, is smaller than the yield strength of the alloys with only irradiation loops and is approximately same for the alloy with composition inhomogeneity alone. We identify this destructive interference in the superposition in our parallel TEM in situ tensile tests on unirradiated, ion irradiated, and neutron irradiated C35M FeCrAl alloy as well. This destructive interference in the hardening contributions contrasts with the widely utilized dispersed barrier hardening (DBH) models by the experimental community to model the hardening contributions due to different irradiation induced defects. Materials science ; Irradiation ; Hardening (computing) ; Nanopillar ; Alloy ; Ultimate tensile strength ; Dislocation ; Composite material ; Plasticity ; Nanotechnology ; Nuclear physics ; Physics ; Nanostructure Fusion materials and technologies ; Ion-surface interactions and analysis ; Microstructure and mechanical properties
Authors: Raghav Tewari | Ritu Joshi
Source: Journal of Spectroscopy (article, 2023-01-01)
Field: Chemistry — Analytical Chemistry

In Situ Compositional Analysis of Tomato Plants and Cell Wall Using Fiber Optic Fourier‐Transform Near‐Infrared Spectroscopy This research was intended to define and interpret cell wall attributes and other chemical composition of eight different varieties of tomato plants by utilizing fiber optic Fourier‐transform near‐infrared spectroscopy (FT‐NIR) to acquire in situ chemical signatures of leaf, flower, fruit, and stem of tomato plant and cell wall at different developmental stages. Chemical spectral signatures of the tomato’s leaf, flower, fruit, and stem were only acquired during its session and in live mode such as green, yellow, and red in cell wall color. The spectral signature analysis of each tomato plant was performed to see substantial differences in chemical compositions using chemometric data modeling of FT‐NIR spectra. In addition, principal component analysis (PCA) was performed to discriminate leaf, flower, fruit, and stem from the same variety. PCA was also performed to differentiate eight different varieties of tomato plants. The study showed how in situ FT‐NIR could distinguish eight types of tomato leaf, flower, fruit, and stem chemical composition at different developmental stages related to cell wall and other attributes. This study has also demonstrated how in situ FT‐NIR can discriminate between rusty vs. healthy leaf and intact fruit vs. off‐the‐plant fruit. The main objective of this study is to present the chemical signature differences in the live and developing tomato plants to improve crucial factors of tomatoes that would benefit plant breeding, tomato cell wall study, and ultimately human health. Principal component analysis ; Chemical composition ; In situ ; Cell wall ; Fourier transform infrared spectroscopy ; Botany ; Spectral signature ; Chemical constituents ; Horticulture ; Biology ; Chemistry ; Mathematics ; Chromatography ; Remote sensing ; Optics Spectroscopy and Chemometric Analyses ; Leaf Properties and Growth Measurement ; Phytochemicals and Antioxidant Activities
Authors: Laraib Ul Nissa | Rabia Amir | Misbah Noreen | S. K. Karim | Muhammad Adeel Shahzad | Muhammad Arief Irfan | Muhammad Yasir
Source: European Journal of Applied Science Engineering and Technology (article, 2023-12-01)
Field: Materials Science — Materials Chemistry

Magnetic Properties of M-Type Hexagonal Ferrite: Mechanical Applications As the information era continues to advance at a rapid pace, M-type strontium ferrite and other magnetic materials are finding more and more traditional uses. Numerous industries rely on it as a permanent magnet material because of its inexpensive cost, ease of preparation, and outstanding overall performance in areas including electronics, national defense, and communication. In this paper, we investigate some the magnetoelectric coupling properties at room temperature by solid phase method and sol-gel method. The phase structure was determined using an X-ray diffractometer, and the samples were all single-phase polycrystalline with a spatial group of P63/mmc. Observing the surface morphology using field emission scanning electron microscopy, it was found that the composition distribution of the samples prepared by solid-phase method was uneven and there was a "scandium rich phase". The samples prepared by the sol gel method have uniform composition distribution, hexagonal grain shape, and grain size of about 3-5 μ M. The magnetic properties of the samples prepared by the sol gel method and the solid phase method were studied, respectively. The results showed that the phase transition occurred in the solid phase method at about 250K, and the hysteresis loop at room temperature did not show the magnetoelectric coupling behavior. The magnetic phase transition of the sample prepared by the sol gel method occurred near 330K. Combined with the research on the hysteresis loops of the temperature above and below this phase transition point, it shows that this phase transition corresponds to the change of the ferromagnetic to the conical magnetic structure. The similar relationship between magnetic capacitance and magnetization intensity with magnetic field indicates that this conical magnetic structure can induce ferroelectric polarization, which can be understood based on the inverse Dzyaloshinskii-Moriya model. Materials science ; Hexagonal crystal system ; Ferrite (magnet) ; Composite material ; Crystallography ; Chemistry Magnetic Properties and Synthesis of Ferrites ; Multiferroics and related materials ; Iron oxide chemistry and applications
Authors: M. Szűcs | Viktor Kárpáti | Tamás Mikó | László S. Tóth
Source: Materials (article, 2023-11-10)
Field: Materials Science — Materials Chemistry

Compression Behavior and Textures of Ti57-Nb43 Alloy at High Temperatures The mechanical behavior, microstructures, as well as the crystallographic textures of the Ti57-Nb43 alloy were investigated on cylindrical specimens compressed at high temperatures, in the range of 700-1000 °C, and strain rates between 0.001 and 1.0 s<sup>-1</sup>. Hardening, followed by softening behaviors, were observed as a function of strain due to the occurrence of dynamic recrystallization/recovery in hot deformation. The modified five-parameter Voce-type equation described well the stress-strain curves, but, for the present alloy, it was also possible with only four parameters. A new two-variables polynomial function was employed on the four parameters that described well the flow curves as a direct function of temperature and strain rate. It permitted the reduction in the number of parameters and had the predictive capacity for the flow stress at any temperature, strain, and strain rate in the investigated range. The crystallographic textures were similar at all temperatures, with an increase in intensity from 900 °C. The textures could be characterized by a double <100> and <111> fiber and a unique component of (001) <110>, the latter inherited from the initial hot-rolling texture. Viscoplastic polycrystal self-consistent deformation modeling reproduced the measured textures showing that dynamic recrystallization did not alter the development of the deformation texture, only increased its intensity. Materials science ; Alloy ; Compression (physics) ; Composite material Titanium Alloys Microstructure and Properties ; Intermetallics and Advanced Alloy Properties ; Aluminum Alloys Composites Properties
Authors: Haimyapriya Buragohain | Kaushik Talukdar
Source: ChemRxiv (preprint, 2023-11-29)
Field: Chemistry — Physical and Theoretical Chemistry

Exploring Computational Chemistry with ChemCompute In this article, we review ChemCompute, a free web platform providing access to various open-source electronic structure and molecular dynamics software packages for exploring the structure and properties of chemical systems. We also illustrate how one can introduce high-quality computational chemistry in undergraduate lab courses without any financial limitations using this platform. Finally, an overview of its existing features and their possible applications in the lab experiments, which can benefit undergraduate students as beginners to computational chemistry, is presented. Computer science ; Software ; Quality (philosophy) ; Computational science ; Chemistry ; Software engineering ; Data science ; Programming language ; Physics Various Chemistry Research Topics ; History and advancements in chemistry ; Molecular Junctions and Nanostructures
Authors: Jean de Bruin Jordaan | Ken Nixon | Craig S. Carlson | Michiel Postema
Source: BIO Integration (article, 2023-01-01)
Field: Materials Science — Materials Chemistry

First experiments with carbon black pigment dispersion acting as a Janus ultrasound contrast agent Abstract Background: Theranostic ultrasound contrast agents comprise a therapeutic component whose controlled release is triggered by an ultrasound pulse. However, once the therapeutic component has been released from an ultrasound contrast agent microbubble, its intended uptake cannot be monitored, as its acoustically active host has been destroyed. Acoustic Janus particles, whose hydrophobic and hydrophilic properties depend on the external acoustic regime, are of potential use as contrast agents and drug-delivery tracers. The purpose of this study was to evaluate the hypothesis that submicron particles with Janus properties may act as ultrasound contrast agents whose hydrophobicity changes over time. Methods: Fifty samples of carbon black were subjected to 5-minute sonication with pulses with a center frequency of 10 MHz and a 1% duty cycle, after which the optical absorption coefficients were measured in n -octanol and water. These coefficients were compared with those of unsonicated samples. Results: Our preliminary results show that the difference between the linear absorption coefficients of sonicated and unsonicated samples was Δα = 80 ± 13 m −1 immediately after sonication, indicating that the carbon black particles were less hydrophobic after sonication than prior to it. Forty-eight hours after sonication, the difference in linear optical absorption coefficients had lessened to Δα = 16 ± 9 m −1 , indicating that the carbon black particles had become more hydrophobic over time, but not equal to the hydrophobicity situation prior to sonication. Conclusion: The experiments confirmed that submicron carbon black particles have acoustic Janus properties. Sonication ; Carbon black ; Ultrasound ; Absorption (acoustics) ; Materials science ; Janus ; Dispersion (optics) ; Carbon fibers ; Therapeutic ultrasound ; Contrast (vision) ; Particle size ; Chemistry ; Chromatography ; Nanotechnology ; Composite material ; Acoustics ; Optics ; Composite number Ultrasound and Cavitation Phenomena ; Ultrasound and Hyperthermia Applications ; Electrospun Nanofibers in Biomedical Applications