jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Annika M. Krieger | Vivek Sinha | Guanna Li | Evgeny A. Pidko
Source: Organometallics (article, 2022-04-15)
Field: Chemistry — Inorganic Chemistry

Solvent-Assisted Ketone Reduction by a Homogeneous Mn Catalyst The choice of a solvent and the reaction conditions often defines the overall behavior of a homogeneous catalytic system by affecting the preferred reaction mechanism and thus the activity and selectivity of the catalytic process. Here, we explore the role of solvation in the mechanism of ketone reduction using a model representative of a bifunctional Mn-diamine catalyst through density functional theory calculations in a microsolvated environment by considering explicit solvent and fully solvated ab initio molecular dynamics simulations for the key elementary steps. Our computational analysis reveals the possibility of a Meerwein-Ponndorf-Verley (MPV) type mechanism in this system, which does not involve the participation of the N-H moiety and the formation of a transition-metal hydride species in ketone conversion. This path was not previously considered for Mn-based metal-ligand cooperative transfer hydrogenation homogeneous catalysis. The MPV mechanism is strongly facilitated by the solvent molecules present in the reaction environment and can potentially contribute to the catalytic performance of other related catalyst systems. Calculations indicate that, despite proceeding effectively in the second coordination sphere of the transition-metal center, the MPV reaction path retains the enantioselectivity preference induced by the presence of the small chiral <i>N</i>,<i>N</i>'-dimethyl-1,2-cyclohexanediamine ligand within the catalytic Mn(I) complex. Chemistry ; Catalysis ; Ketone ; Hydride ; Bifunctional ; Transition state ; Solvation ; Ligand (biochemistry) ; Coordination sphere ; Homogeneous catalysis ; Moiety ; Solvent ; Solvent effects ; Methyl vinyl ketone ; Computational chemistry ; Combinatorial chemistry ; Molecule ; Metal ; Organic chemistry Asymmetric Hydrogenation and Catalysis ; Catalysis for Biomass Conversion ; Nanomaterials for catalytic reactions
Authors: Zahra Rajabi | Michela Martinelli | Gabriel F. Upton | Caleb D. Watson | Donald C. Cronauer | A. Jeremy Kropf | Gary Jacobs
Source: Catalysis Today (article, 2022-06-17)
Field: Materials Science — Materials Chemistry

Low temperature ethanol steam reforming: Selectivity control with lithium doping of Pt/m-ZrO2 Chemistry ; Catalysis ; Steam reforming ; Selectivity ; Formate ; Methanation ; Decarbonylation ; Inorganic chemistry ; Water-gas shift reaction ; Desorption ; Methanol ; Photochemistry ; Hydrogen production ; Physical chemistry ; Adsorption ; Organic chemistry Catalytic Processes in Materials Science ; Catalysts for Methane Reforming ; Ammonia Synthesis and Nitrogen Reduction
Authors: Minfang Zhang | Mei Yang | Yuki Okigawa | Takatoshi Yamada | H. Nakajima | Yoko Iizumi | Toshiya Okazaki
Source: Scientific Reports (article, 2022-03-16)
Field: Materials Science — Materials Chemistry

Patterning of graphene using wet etching with hypochlorite and UV light Graphene patterning via etching is important for enhancing or controling the properties of devices and supporting their applications in micro- and nano-electronic fields. Herein, we present a simple, low-cost, and scalable wet etching method for graphene patterning. The technique uses hypochlorite solution combined with ultraviolet light irradiation to rapidly remove unwanted graphene areas from the substrate. Raman spectroscopy, atomic force microscopy, scanning electron microscopy, and optical microscopy results showed that well-patterned graphene with micrometer scale regions was successfully prepared. Furthermore, graphene field effect transistor arrays were fabricated, and the obtained devices exhibited good current-voltage characteristics, with maximum mobility of ~ 1600 cm<sup>2</sup>/Vs, confirming the feasibility of the developed technique. Graphene ; Materials science ; Raman spectroscopy ; Etching (microfabrication) ; Nanotechnology ; Optoelectronics ; Micrometer ; Substrate (aquarium) ; Ultraviolet ; Scanning electron microscope ; Ultraviolet light ; Optics ; Composite material Graphene research and applications ; Graphene and Nanomaterials Applications ; 2D Materials and Applications
Authors: Churna Bhandari | Durga Paudyal
Source: Physical Review Research (article, 2022-04-05)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Enhancing stability and magnetism of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>ThMn</mml:mi><mml:mn>12</mml:mn></mml:msub></mml:math>-type cerium-iron intermetallics by site substitution There is considerable research interest in discovering new permanent magnetic materials that perform equally as champion neomagnets, with the minimal use of critical rare-earth elements. Recently ${\mathrm{ThMn}}_{12}$-type (1:12) rare-earth iron (Ce-Fe) intermetallic materials have been on the frontline of research as Ce is naturally abundant that drastically lowers the cost of permanent magnets. Here, we investigate the lattice stability and electronic and magnetic properties of Ti- or Zr-substituted ${\mathrm{CeFe}}_{12}$ and ${\mathrm{CeFe}}_{12}\mathrm{N}$ using density functional theory. We find negative formation energy for all compositions in the bulk structure with respect to unaries except for ${\mathrm{CeFe}}_{12}$. The inclusion of nitrogen in the interstitial sites of ${\mathrm{CeFe}}_{12}$ improves its chemical stability by reducing the formation energy. The first time successfully calculated phonon frequencies including $4f$ electrons indicate that all compositions are dynamically stable. With the help of electronic structure calculations, we demonstrate that cerium exhibits the mixed-valence character in 1:12 materials. The mixed-valency sensibly affects the magnetocrystalline anisotropy (MCA) and magnetic moment. Nitrogen improves the net magnetic moment by influencing the spin polarization with extra electrons, although it has the opposite effect in the MCA constant, ${K}_{1}$. The predicted value of ${K}_{1}$ confirms all compounds uniaxial along the crystalline $c$ axis. Especially for ${\mathrm{CeZrFe}}_{11}$, ${K}_{1}$ is the largest in which Ce exhibits ${\mathrm{Ce}}^{3+}$ $(S=1/2)$, and $\mathrm{Ce}(4f)$ spin-density contour is elongated towards the uniaxial direction. The substantially large values of the MCA and magnetic moments suggest that these critical element-free materials qualify for high-performance permanent magnets. Magnetism ; Magnetic moment ; Materials science ; Density functional theory ; Magnetocrystalline anisotropy ; Condensed matter physics ; Crystallography ; Physics ; Machine learning ; Magnetic anisotropy ; Chemistry ; Quantum mechanics ; Computer science ; Magnetization Magnetic Properties of Alloys ; Magnetic properties of thin films ; Rare-earth and actinide compounds
Authors: Matthew Rosi | Brandon Russell | Line G. Kristensen | Erik R. Farquhar | Rohit Jain | Donald Abel | Michael Sullivan | Shawn M. Costello | María Agustina Domínguez-Martín | Yan Chen | Susan Marqusee | Christopher J. Petzold | Cheryl A. Kerfeld | Daniel P. DePonte | Farid Farahmand | Sayan Gupta | Corie Y. Ralston
Source: Communications Biology (article, 2022-08-25)
Field: Chemistry — Spectroscopy

An automated liquid jet for fluorescence dosimetry and microsecond radiolytic labeling of proteins X-ray radiolytic labeling uses broadband X-rays for in situ hydroxyl radical labeling to map protein interactions and conformation. High flux density beams are essential to overcome radical scavengers. However, conventional sample delivery environments, such as capillary flow, limit the use of a fully unattenuated focused broadband beam. An alternative is to use a liquid jet, and we have previously demonstrated that use of this form of sample delivery can increase labeling by tenfold at an unfocused X-ray source. Here we report the first use of a liquid jet for automated inline quantitative fluorescence dosage characterization and sample exposure at a high flux density microfocused synchrotron beamline. Our approach enables exposure times in single-digit microseconds while retaining a high level of side-chain labeling. This development significantly boosts the method's overall effectiveness and efficiency, generates high-quality data, and opens up the arena for high throughput and ultrafast time-resolved in situ hydroxyl radical labeling. Microsecond ; Radiolysis ; Synchrotron ; Chemistry ; In situ ; Fluorescence ; Jet (fluid) ; Analytical Chemistry (journal) ; Optics ; Chromatography ; Radical ; Physics ; Organic chemistry Mass Spectrometry Techniques and Applications ; Microfluidic and Capillary Electrophoresis Applications ; Innovative Microfluidic and Catalytic Techniques Innovation
Authors: Mohamed Salaheldeen | Asma Wederni | M. Ipatov | J. González | V. Zhukova | А. Zhukov
Source: Crystals (article, 2022-12-04)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Elucidation of the Strong Effect of the Annealing and the Magnetic Field on the Magnetic Properties of Ni2-Based Heusler Microwires We study the effect of annealing and the applied magnetic field from 50 Oe to 20 kOe on the magneto-structural behavior of Ni2FeSi-based Heusler microwires fabricated by using Taylor-Ulitovsky technique. Using the XRD analysis, a strong effect of annealing, manifested as the development of the crystallization process, was observed. The average grain size and crystalline phase content of annealed sample increase from 21.3 nm and 34% to 32.8 nm and 79%, respectively, as-compared to the as-prepared one. In addition, upon annealing, phase transforms into a monoclinic martensitic structure with a modulation of 10 M, which cannot be found in the as-prepared sample. Concerning the magnetic properties, both samples show ferromagnetic behavior below and above the room temperature, where the Curie temperature of Ni2FeSi is higher than the room temperature. The induced secondary phases have a noticeable effect on the magnetic behavior of the annealed sample, where a high normalized saturation magnetization (NMs) and low normalized reduced remenance (Mr = M/M5K), compared to the as-prepared have been detected. Additionally, the coercivity of annealed sample shows one flipping point at 155 K where its behavior changes with temperature. Meanwhile, the as-prepared sample show two flipped point at 205 K and 55 K. A mismatch between field cooling (FC) and field heating (FH) magnetization curves with temperature has been detected for annealed sample at low applied magnetic field. The difference in magnetic and structure behavior of Ni2FeSi microwires sample is discussed considering the effect of induced internal stresses by the presence of a glass coating and the recrystallization and stresses relaxation upon annealing. Materials science ; Coercivity ; Annealing (glass) ; Curie temperature ; Condensed matter physics ; Ferromagnetism ; Magnetic field ; Magnetization ; Monoclinic crystal system ; Metallurgy ; Crystallography ; Crystal structure ; Chemistry ; Physics Heusler alloys: electronic and magnetic properties ; Shape Memory Alloy Transformations ; Magnetic properties of thin films
Authors: Y. Zamora Garcia | Michael Martin | M.D. Ynsa | V. Torres‐Costa | Miguel L. Crespillo | M. Tardı́o | J. Olivares | Federico Bosia | O. Peña | J. Nicolas | Massimo Tallarida
Source: The European Physical Journal Plus (article, 2022-10-19)
Field: Materials Science — Materials Chemistry

Process design for the manufacturing of soft X-ray gratings in single-crystal diamond by high-energy heavy-ion irradiation Abstract This paper describes in detail a novel manufacturing process for optical gratings suitable for use in the UV and soft X-ray regimes in a single-crystal diamond substrate based on highly focused swift heavy-ion irradiation. This type of grating is extensively used in light source facilities such as synchrotrons or free electron lasers, with ever-increasing demands in terms of thermal loads, depending on beamline operational parameters and architecture. The process proposed in this paper may be a future alternative to current manufacturing techniques, providing the advantage of being applicable to single-crystal diamond substrates, with their unique properties in terms of heat conductivity and radiation hardness. The paper summarizes the physical principle used for the grating patterns produced by swift heavy-ion irradiation and provides full details for the manufacturing process for a specific grating configuration, inspired in one of the beamlines at the ALBA synchrotron light source, while stressing the most challenging points for a potential implementation. Preliminary proof-of-concept experimental results are presented, showing the practical implementation of the methodology proposed herein. Grating ; Beamline ; Diamond ; Materials science ; Irradiation ; Optics ; Synchrotron radiation ; Optoelectronics ; Substrate (aquarium) ; Process (computing) ; Radiation hardening ; Radiation ; Computer science ; Physics ; Composite material ; Nuclear physics Diamond and Carbon-based Materials Research ; Integrated Circuits and Semiconductor Failure Analysis ; Advanced Surface Polishing Techniques
Authors: Hsing-Yu Wu | Shaorong Huang | Chih-Hsuan Shih | Li‐Jen Hsiao | Hongwei Chen | Ming-Chung Cheng | Jin–Cherng Hsu
Source: Nanomaterials (article, 2022-03-23)
Field: Materials Science — Surfaces, Coatings and Films

Highly Reflective Silver-Enhanced Coating with High Adhesion and Sulfurization Resistance for Telescopes Highly reflective metal coatings are essential for manufacturing reflecting telescope mirrors to achieve the highest reflectivity with broad spectral bandwidth. Among metallic materials, enhanced silver-based coatings can provide higher reflectivity in the 400-500 nm spectral range to better performance from visible to near IR. Moreover, over-coating a dielectric protective layer on the mirror's front side attains additional hardness and oxidation stability. In this paper, we study a combination of thermal and electron beam evaporation as a technology to form protected enhanced high reflective Ag coatings. A newly designed multiplayer film can pass ASTM 5B adhesive performance testing and give sulfurization inhibition. The average specular reflectivity for the enhancement coating is about 98% in wavelengths across the spectral range from 400-1000 nm. This innovation has been demonstrated on a Newtonian type telescope, with storage in an ambiance humidity H = 60-85%, and temperature T = 10-35 °C, for more than six months without degradation in coating performance. Materials science ; Coating ; Anti-reflective coating ; Optical coating ; Specular reflection ; Composite material ; Optics ; Adhesive ; Silicone resin ; Layer (electronics) ; Electron beam physical vapor deposition ; Optoelectronics ; Thin film ; Nanotechnology Optical Coatings and Gratings ; Advanced optical system design ; Thin-Film Transistor Technologies
Authors: Jerome Lloyd | Sounak Biswas | Steven H. Simon | S. A. Parameswaran | Felix Flicker
Source: Physical review. B./Physical review. B (article, 2022-09-12)
Field: Materials Science — Materials Chemistry

Statistical mechanics of dimers on quasiperiodic Ammann-Beenker tilings We study classical dimers on two-dimensional quasiperiodic Ammann-Beenker (AB) tilings. Using the discrete scale-symmetry of quasiperiodic tilings, we prove that each infinite tiling admits ``perfect matchings'', where every vertex is touched by one dimer. We show the appearance of so-called monomer pseudomembranes. These are sets of edges, which collectively host exactly one dimer, which bound certain eightfold-symmetric regions of the tiling. Regions bounded by pseudomembranes are matched together in a way that resembles perfect matchings of the tiling itself. These structures emerge at all scales, suggesting the preservation of collective dimer fluctuations over long distances. We provide numerical evidence, via Monte Carlo simulations, of dimer correlations consistent with power laws over a hierarchy of different lengthscales. We also find evidence of rich monomer correlations, with monomers displaying a pattern of attraction and repulsion to different regions within pseudomembranes, along with signatures of deconfinement within certain annular regions of the tiling. Substitution tiling ; Quasiperiodic function ; Combinatorics ; Dimer ; Disjoint sets ; Quasicrystal ; Hexagonal tiling ; Penrose tiling ; Mathematics ; Partition function (quantum field theory) ; Physics ; Geometry ; Quantum mechanics ; Mathematical analysis ; Grid Quasicrystal Structures and Properties ; Theoretical and Computational Physics ; Diffusion and Search Dynamics
Authors: Qinglei Ji | Xi Vincent Wang | Lihui Wang | Lei Feng
Source: Control Engineering Practice (article, 2022-07-01)
Field: Materials Science — Polymers and Plastics

Online reinforcement learning for the shape morphing adaptive control of 4D printed shape memory polymer Combining 3D printing and smart materials, 4D printing technologies enable the printed actuators to further change their shapes or other properties after prototyping. However, the shape morphing of 4D printed actuators suffers from poor controllability and low precision. One of the main challenges is that the 4D printed actuators are hard to be modeled and it is difficult to develop an appropriate controller for them. In this study, various popular reinforcement learning (RL) methods are applied to address the problem of online and adaptive model-free control of 4D printed shape memory polymer (SMP). Their training efficiencies are compared and an adaptive LQR controller based on Q learning is developed to realize efficient online learning. The RL controller achieves precise and quick shape control within 2−−3 learning episodes and is adaptive to the changing properties of SMP. The RL controller performance is then compared with a model-based LQR controller and shows high control precision and excellent adaptability to the varying control plant. Morphing ; Reinforcement learning ; Actuator ; Controller (irrigation) ; Controllability ; Computer science ; Adaptability ; Adaptive control ; Control engineering ; Control (management) ; Artificial intelligence ; Engineering Polymer composites and self-healing ; Advanced Materials and Mechanics ; Dielectric materials and actuators
Authors: Jing Tian | Xinyu Chen | Zhennan Liang | Wen-Liang Qi | Xiaohuan Zheng | Daoli Lu | Bin Chen
Source: Journal of Food Quality (article, 2022-04-12)
Field: Chemistry — Analytical Chemistry

Application of NIR Spectral Standardization Based on Principal Component Score Evaluation in Wheat Flour Crude Protein Model Sharing In order to explore spectral standardization methods for spectra collected by different NIR spectrometers, to reduce spectral differences, and to realize model sharing among different instruments, the crude protein content of 154 wheat flour samples was measured using one grating and three Fabry-Perot tunable filter NIR spectrometers in wavelength. At the same wavelength range and wavelength interval, three algorithms, namely, direct standardization (DS), piecewise direct standardization (PDS), and simple linear regression direct standardization (SLRDS), were used to standardize spectra collected by different instruments from the same samples. Spectral standardization error rate (SSER), principal component score error rate (PCSER), and other indicators were employed to analyze the spectral differences between the master and the target spectra, and the effect of model sharing was evaluated using parameters including prediction correlation coefficient (Rp), root mean square error of prediction (RMSEP), and relative prediction deviation (RPD). The results show the following: (1) The difference between spectra can be quantitatively evaluated through analyzing SSER and PCSER. (2) After standardization by the three algorithms, the spectral difference between the three target and the master spectrometers is significantly reduced and the prediction effect of the master model is greatly improved. (3) Among the three algorithms, DS algorithm had the smallest error rate in standardizing spectra from three target spectrometers. After standardization by the DS algorithm, the master model had the best effect. Its prediction accuracy was greatly improved compared with that before standardization. (4) The standard model established based on the S450 spectrometer can be applied to the same spectrometer as the N500 spectrometer with the same resolution and different wavelength ranges, so as to achieve model sharing. Therefore, DS, PDS, and SLRDS algorithms can effectively reduce the spectral differences between different instruments and realize the sharing of NIR calibration models for wheat flour crude protein measurement. Standardization ; Spectrometer ; Principal component analysis ; Mean squared error ; Correlation coefficient ; Standard error ; Mathematics ; Biological system ; Spectral line ; Principal component regression ; Calibration ; Statistics ; Computer science ; Algorithm ; Optics ; Physics Spectroscopy and Chemometric Analyses ; Water Quality Monitoring and Analysis ; Spectroscopy Techniques in Biomedical and Chemical Research
Authors: Cuong Viet Bui | Thomas Rosenau | Hubert Hettegger
Source: Cellulose (article, 2022-10-25)
Field: Chemistry — Spectroscopy

Synthesis by carbonate aminolysis and chiral recognition ability of cellulose 2,3-bis(3,5-dimethylphenyl carbamate)-6-(α-phenylethyl carbamate) selectors Abstract Novel chiral selectors based on cellulose 2,3- bis (3,5-dimethylphenyl carbamate)-6-( α -phenylethyl carbamate) were regioselectively synthesized by carbonate aminolysis and isocyanate chemistry. By oxycarbonylation with phenyl chloroformate, carbamoylation with 3,5-dimethylphenyl isocyanate, and subsequent aminolysis of the previously introduced reactive carbonate moiety at C6 with enantiopure ( R )-or ( S )- α -phenylethylamine, chiral selectors have been obtained, which regioselectively carry two different phenyl carbamate substituents. The cellulose derivatives were comprehensively characterized by ATR-FTIR, solid-state NMR, GPC, and elemental analysis. In parallel, 3-aminopropyl-functionalized silica gel as an inert carrier material for the chiral selectors was prepared and the obtained coated-type chiral stationary phases were characterized by both solid-state 29 Si NMR, 13 C NMR, and elemental analysis. The enantioseparation performance of the chiral selectors was studied and compared to cellulose tris (3,5-dimethylphenyl carbamate) as a reference. With this protocol in hand, certain shortcomings of conventional approaches towards the regioselective synthesis of polysaccharide-based chiral selectors were overcome, such as the limitation to standard isocyanate reagents, being able to apply now the whole wealth of commercially available (chiral) primary and also secondary alkylamines instead. Graphical abstract Isocyanate ; Aminolysis ; Carbamate ; Cellulose ; Organic chemistry ; Chemistry ; Moiety ; Polyurethane ; Catalysis Analytical Chemistry and Chromatography ; Advanced NMR Techniques and Applications ; Molecular spectroscopy and chirality