jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Sujeet Dutta | Anne Galarneau | Delphine Minoux | Cindy Aquino | J.-P. Dath | Flavien Guenneau | Benoît Coasne
Source: The Journal of Physical Chemistry C (article, 2023-01-11)
Field: Chemistry — Spectroscopy

Molecular Diffusion in Hierarchical Zeolites with Ordered Mesoporosity: Pulsed Field Gradient Nuclear Magnetic Resonance Combined with Thermodynamic Modeling The dynamics of fluids confined in hierarchical porous materials is gaining increasing attention. Here, using pulsed field gradient nuclear magnetic resonance, we report an experimental study of the self-diffusivity of cyclohexane confined at different temperatures in the bi-porous structure of hierarchical faujasite zeolites (i.e., combining the intrinsic zeolite microporosity of < 2 nm diameter and an ordered MCM-41-like mesoporosity of 4 nm diameter). For different mesoporous volumes, we consider cyclohexane self-diffusivity at chemical potentials where the porosity is either totally or only partially filled (in the latter case, the microporosity is completely filled, while the mesoporous surface is only covered by a molecular thin film). On one hand, in completely filled materials, as expected, the effective cyclohexane self-diffusivity is found to increase as the mesoporous volume increases. Moreover, in this regime, the self-diffusivity follows an Arrhenius behavior with an activation energy that is close to─although slightly smaller than─that for bulk cyclohexane. On the other hand, for partially filled materials, a striking behavior is observed as the measured self-diffusivity decreases upon increasing the loading and remains nearly constant upon increasing the temperature. We propose here that such a behavior can be rationalized by considering (1) the population redistribution between the microporosity and mesoporosity (including the gas phase in the mesopores) and (2) the effective number of molecules that contribute to spin echo attenuation upon increasing the temperature. In particular, while molecules diffuse faster overall with the increasing temperature, we show here that our measurements rely at each temperature on a slower and slower population (therefore leading to unexpected temperature variations). Thermal diffusivity ; Cyclohexane ; Mesoporous material ; Materials science ; Porosity ; Pulsed field gradient ; Population ; Diffusion ; Arrhenius equation ; Chemical physics ; Thermodynamics ; Activation energy ; Chemistry ; Physical chemistry ; Composite material ; Organic chemistry Advanced NMR Techniques and Applications ; NMR spectroscopy and applications ; Zeolite Catalysis and Synthesis
Authors: Jinsong Yan | Zongyi Ma | Jianquan Xu | Haoran Nie | Hailin Yuan | Xinping Wang | Tong Wang | Lu‐Tao Weng | Ophelia K. C. Tsui
Source: Macromolecules (article, 2023-07-27)
Field: Materials Science — Materials Chemistry

Glass Transition of the Surface Monolayer of Polystyrene Films: Effect of Thermal Preannealing In a previous experiment, we observed that the glass transition temperature of the surface monolayer glass transition temperature (Tgsurf) of unannealed polystyrene (PS) films spin-coated on oxide-coated silicon decreased with decreasing film thickness (h < ∼60 nm). However, this h dependence could be removed by thermal preannealing. In this experiment, we investigated the origin of this preannealing effect. We found that Tgsurf of the thin films increased with preannealing time (tANN) and reached the steady-state thick-film value at a characteristic time (τsurf) following the τsurf ∼ h2 scaling for diffusion. Moreover, chain adsorption occurred alongside the increase in Tgsurf during thermal preannealing and reached the steady-state adsorbed amount at a time similar to τsurf. We tentatively suggest that the observed increase in Tgsurf with tANN was caused by diffusion of free-volume holes from the polymer–substrate interface to the free surface due to densification of the interfacial polymer upon chain adsorption. Monolayer ; Polystyrene ; Adsorption ; Polymer ; Glass transition ; Materials science ; Diffusion ; Substrate (aquarium) ; Polymer chemistry ; Analytical Chemistry (journal) ; Chemistry ; Composite material ; Thermodynamics ; Nanotechnology ; Physical chemistry ; Chromatography ; Geology Material Dynamics and Properties ; Liquid Crystal Research Advancements ; Adhesion, Friction, and Surface Interactions
Authors: N.A. Sazelee | Muhamad Faiz Md Din | M. Ismail
Source: Materials (article, 2023-03-08)
Field: Materials Science — Materials Chemistry

Ni0.6Zn0.4O Synthesised via a Solid-State Method for Promoting Hydrogen Sorption from MgH2 Magnesium hydrides (MgH<sub>2</sub>) have drawn a lot of interest as a promising hydrogen storage material option due to their good reversibility and high hydrogen storage capacity (7.60 wt.%). However, the high hydrogen desorption temperature (more than 400 °C) and slow sorption kinetics of MgH<sub>2</sub> are the main obstacles to its practical use. In this research, nickel zinc oxide (Ni<sub>0.6</sub>Zn<sub>0.4</sub>O) was synthesized via the solid-state method and doped into MgH<sub>2</sub> to overcome the drawbacks of MgH<sub>2</sub>. The onset desorption temperature of the MgH<sub>2</sub>-10 wt.% Ni<sub>0.6</sub>Zn<sub>0.4</sub>O sample was reduced to 285 °C, 133 °C, and 56 °C lower than that of pure MgH<sub>2</sub> and milled MgH<sub>2</sub>, respectively. Furthermore, at 250 °C, the MgH<sub>2</sub>-10 wt.% Ni<sub>0.6</sub>Zn<sub>0.4</sub>O sample could absorb 6.50 wt.% of H<sub>2</sub> and desorbed 2.20 wt.% of H<sub>2</sub> at 300 °C within 1 h. With the addition of 10 wt.% of Ni<sub>0.6</sub>Zn<sub>0.4</sub>O, the activation energy of MgH<sub>2</sub> dropped from 133 kJ/mol to 97 kJ/mol. The morphology of the samples also demonstrated that the particle size is smaller compared with undoped samples. It is believed that in situ forms of NiO, ZnO, and MgO had good catalytic effects on MgH<sub>2</sub>, significantly reducing the activation energy and onset desorption temperature while improving the sorption kinetics of MgH<sub>2</sub>. Hydrogen storage ; Magnesium hydride ; Desorption ; Activation energy ; Materials science ; Sorption ; Non-blocking I/O ; Hydrogen ; Magnesium ; Kinetics ; Chemical engineering ; Inorganic chemistry ; Catalysis ; Chemistry ; Metallurgy ; Adsorption ; Physical chemistry ; Organic chemistry Hydrogen Storage and Materials ; Ammonia Synthesis and Nitrogen Reduction ; Superconductivity in MgB2 and Alloys
Authors: Daniel Voignac | Shylee Belsey | Elisabeth Wermter | Yossi Paltiel | Oded Shoseyov
Source: Nanomaterials (article, 2023-08-06)
Field: Materials Science — Biomaterials

Biobased Electronics: Tunable Dielectric and Piezoelectric Cellulose Nanocrystal—Protein Films Cellulose has been a go-to material for its dielectric properties from the onset of capacitor development. The demand for an energy storage solution continues to grow, but the supply remains limited and relies too often on fossil and mined materials. This work proposes a fully sustainable and green method with which to produce dielectric thin films made of renewable and degradable materials. Cellulose nanocrystals (CNC) made an excellent matrix for the dispersion of proteins and the fabrication of robust transparent thin films with enhanced dielectric permittivity. A range of proteins sources, additives and concentrations allowed for us to control the dielectric permittivity from <i>ε<sub>r</sub></i> = 4 to 50. The proteins screened came from animal and plant sources. The films were formed from drying a water suspension of the CNC and proteins through evaporation-induced self-assembly. This yielded nano-layered structures with very high specific surface areas, ideal for energy storage devices. The resulting films were characterized with respect to the electrical, mechanical, piezoelectric, and optical properties to be compared. Electrically conductive (σ = 1.53 × 10<sup>3</sup> S/m) CNC films were prepared with carbon nanotubes (CNT). The fabricated films were used to make flexible, sustainable, and degradable capacitors by layering protein-based films between CNC-CNT composite films. Materials science ; Dielectric ; Fabrication ; Thin film ; Piezoelectricity ; Evaporation ; Capacitor ; Cellulose ; Nanotechnology ; Composite material ; Optoelectronics ; Chemical engineering ; Voltage Advanced Cellulose Research Studies ; Nanocomposite Films for Food Packaging ; Electrospun Nanofibers in Biomedical Applications
Authors: Junlin Yuan | Conghui Li | Shanshan Wang | Hui Zhang | Zengming Wang | Aiping Zheng | Xiuli Gao
Source: Polymers (article, 2023-02-27)
Field: Chemistry — Spectroscopy

Methods and Characteristics of Drug Extraction from Ion-Exchange-Resin-Mediated Preparations: Influences, Thermodynamics, and Kinetics Since the discovery of ion-exchange resins, they have been used in many fields, including pharmacy. Ion-exchange resin-mediated preparations can realize a series of functions, such as taste masking and regulating release. However, it is very difficult to extract the drug completely from the drug-resin complex because of the specific combination of the drug and resin. In this study, methylphenidate hydrochloride extended-release chewable tablets compounded by methylphenidate hydrochloride and ion-exchange resin were selected for a drug extraction study. The efficiency of drug extraction by dissociating with the addition of counterions was found to be higher than other physical extraction methods. Then, the factors affecting the dissociation process were studied to completely extract the drug from the methylphenidate hydrochloride extended-release chewable tablets. Furthermore, the thermodynamic and kinetic study of the dissociation process showed that the dissociation process obeys the second-order kinetic process, and it is nonspontaneous, entropy-decreasing, and endothermic. Meanwhile, the reaction rate was confirmed by the Boyd model, and the film diffusion and matrix diffusion were both shown to be rate-limiting steps. In conclusion, this study aims to provide technological and theoretical support for establishing a quality assessment and control system of ion-exchange resin-mediated preparations, promoting the applications of ion-exchange resins in the field of drug preparation. Ion-exchange resin ; Chemistry ; Dissociation (chemistry) ; Chromatography ; Drug ; Diluent ; Endothermic process ; Ion exchange ; Materials science ; Ion ; Organic chemistry ; Adsorption ; Pharmacology ; Medicine Analytical Chemistry and Chromatography ; Crystallization and Solubility Studies ; Chemical and Physical Properties in Aqueous Solutions
Authors: Harry Supriadi | Iga Trisnawati | Tri Handini | Sri Rinanti Susilowati | Vincent Sutresno Hadi Sujoto | Panut Mulyono | Himawan Tri Bayu Murti Petrus
Source: Indonesian Journal of Chemistry (article, 2023-03-03)
Field: Chemistry — Inorganic Chemistry

Kinetics Study of Yttrium Leaching from Zircon Tailings Using Sulfuric Acid From the analysis of zircon tailings using X-Ray Fluorescence (XRF), Yttrium is a rare earth element (REE) with the highest concentration compared to other REEs. The purpose of this study is to determine the best kinetic model for describing how sulfuric acid extracts Yttrium from zircon tailings. Leaching temperatures of 200, 250, and 300 °C were used to determine the kinetics. Samples were obtained at 0, 20, 40, 60, 80, 100, and 120 min for each temperature. This study discovered that the chemical reaction model's kinetics are the most closely related to those of the leaching process. The evaluation of the model utilizing the coefficient of determination (R2) on the relationship between each model and time lends support to this conclusion. The activation energy (Ea) of the leaching process is determined by the Arrhenius plot between ln k and 1/T. In the Yttrium leaching procedure, the Ea value is 14.42 kJ/mol. The chemical reaction model was in charge of the leaching process, according to the Ea value. The premise of the chemical reaction model is that chemical reactions regulate the rate of the reaction. Leaching (pedology) ; Yttrium ; Chemistry ; Tailings ; Activation energy ; Zircon ; Sulfuric acid ; Arrhenius equation ; Kinetics ; Scandium ; Chemical kinetics ; Chemical reaction ; Order of reaction ; Inorganic chemistry ; Nuclear chemistry ; Reaction rate constant ; Physical chemistry ; Geology ; Organic chemistry ; Soil science ; Geochemistry Radioactive element chemistry and processing ; Minerals Flotation and Separation Techniques ; Metal Extraction and Bioleaching
Authors: Weizhong Zou | Grace Tan | Mike Weaver | Peter H. Koenig | Ronald G. Larson
Source: Physical Review Research (article, 2023-10-09)
Field: Chemistry — Organic Chemistry

Mesoscopic modeling of the effect of branching on the viscoelasticity of entangled wormlike micellar solutions The effect of branches on the linear rheology of entangled wormlike micelle solutions is modeled by tracking the diffusion of micellar material through branch points. The model is equivalent to a Kirchhoff circuit model with the sliding of an entangled branch along an entanglement tube due to the constrained diffusion of micellar material analogous to the flux of current in the Kirchhoff circuit model. When combined with our previous mesoscopic pointer algorithm for linear micelles that can both break and fuse, the model adds a branch sprouting process and therefore enables simulation of the dynamics of structural change and stress relaxation in ensembles of micelle clusters of different topologies. Applying this model to study the relationships between fluid rheology and microstructure of micelles, our results show that branches change the scaling law exponents for viscosity vs micelle strand length. This contrasts with the longstanding hypothesis that branches affect viscosity and relaxation in the same way that micelle ends do. The model also suggests a process for inferring branching density from salt-dependent linear rheology. This is exemplified by mixed surfactant solutions over a range of salt concentrations with flow properties measured using both mechanical rheometry and diffusing wave spectroscopy. By elucidating the connection between the branching characteristics, such as strand length and branching density, with the nonmonotonic variation of solution viscosity, the above model provides a powerful tool to help extract branching information from rheology. Branching (polymer chemistry) ; Rheology ; Viscoelasticity ; Micelle ; Mesoscopic physics ; Materials science ; Reptation ; Scaling ; Rheometry ; Viscosity ; Stress relaxation ; Chemical physics ; Thermodynamics ; Chemistry ; Polymer ; Physics ; Mathematics ; Condensed matter physics ; Physical chemistry ; Composite material ; Aqueous solution ; Geometry Surfactants and Colloidal Systems ; Material Dynamics and Properties ; Electrostatics and Colloid Interactions
Authors: S. N. Yudin | I. A. Alimov | Sergey Volodko | Alexander Gurianov | Galina Markova | А. В. Касимцев | Т. А. Свиридова | Darya Permyakova | E. V. Evstratov | В. В. Чеверикин | Dmitry Moskovskikh
Source: Journal of Functional Biomaterials (article, 2023-05-13)
Field: Materials Science — Materials Chemistry

Fabrication of Biomedical Ti-Zr-Nb by Reducing Metal Oxides with Calcium Hydride In the present study, a powder of Ti-18Zr-15Nb biomedical alloy with spongy morphology and with more than 95% vol. of β-Ti was obtained by reducing the constituent oxides with calcium hydride. The influence of the synthesis temperature, the exposure time, and the density of the charge (TiO<sub>2</sub> + ZrO<sub>2</sub> + Nb<sub>2</sub>O<sub>5</sub> + CaH<sub>2</sub>) on the mechanism and kinetics of the calcium hydride synthesis of the Ti-18Zr-15Nb β-alloy was studied. Temperature and exposure time were established as crucial parameters with the help of regression analysis. Moreover, the correlation between the homogeneity of the powder obtained and the lattice microstrain of β-Ti is shown. As a result, temperatures above 1200 °C and an exposure time longer than 12 h are required to obtain a Ti-18Zr-15Nb powder with a single β-phase structure and uniformly distributed elements. The analysis of β-phase growth kinetics revealed that the formation of β-Ti occurs due to the solid-state diffusion interaction between Ti, Nb, and Zr under the calcium hydride reduction of TiO<sub>2</sub> + ZrO<sub>2</sub> + Nb<sub>2</sub>O<sub>5</sub>, and the spongy morphology of reduced α-Ti is inherited by the β-phase. Thus, the results obtained provide a promising approach for manufacturing biocompatible porous implants from β-Ti alloys that are believed to be attractive candidates for biomedical applications. Moreover, the current study develops and deepens the theory and practical aspects of the metallothermic synthesis of metallic materials and can be compelling to specialists in powder metallurgy. Materials science ; Hydride ; Titanium hydride ; Alloy ; Powder metallurgy ; Fabrication ; Chemical engineering ; Metal ; Homogeneity (statistics) ; Titanium alloy ; Kinetics ; Diffusion ; Phase (matter) ; Metallurgy ; Titanium ; Microstructure ; Thermodynamics Titanium Alloys Microstructure and Properties ; Advanced materials and composites ; Orthopaedic implants and arthroplasty
Authors: Menghui Zhou | Juan Li | Guoying Dong | Shufang Gao | Jianghe Feng | Ruiheng Liu
Source: Crystals (article, 2023-04-01)
Field: Materials Science — Materials Chemistry

Enhancement of Thermoelectric Performance for InTe by Selective Substitution and Grain Size Modulation The different masses, ionic radii, and chemical valences of the nonequivalent crystallographic sites of thermoelectric (TE) compounds provide an effective way to modulate the thermoelectric performance by selective substitution. In this work, the selective substitution of In+ by Pb for the binary InTe material monotonically reduces the carrier concentration, which is greatly beneficial to the mechanism investigation of serious grain boundary scattering (GBS). This is the first time this point has been mentioned with regard to InTe material. As a result, we found that GBS was dominated by the grain size when the carrier concentration was higher than 0.7 × 1019 cm−3 but was inversely governed by the carrier concentration when the carrier was situated at a lower density. In particular, the occupation of Pb on the targeted In+ site could further reduce the lattice thermal conductivity. Finally, In0.9999Pb0.0001Te achieved the improved power factor and average zT value, which could contribute to high-power generation below a medium temperature. This effect of increasing the carrier concentration on the suppression of GBS sheds light on the possibility of improving electron mobility by increasing the carrier concentration. Thermoelectric effect ; Grain boundary ; Materials science ; Electron mobility ; Grain size ; Seebeck coefficient ; Thermal conductivity ; Carrier scattering ; Electrical resistivity and conductivity ; Crystallographic defect ; Scattering ; Condensed matter physics ; Analytical Chemistry (journal) ; Optoelectronics ; Thermodynamics ; Chemistry ; Metallurgy ; Optics ; Composite material ; Physics Advanced Thermoelectric Materials and Devices ; Chalcogenide Semiconductor Thin Films ; Thermal properties of materials
Authors: Konstantinos Katsoulas | Monica Tirapelle | Eva Sørensen | Luca Mazzei
Source: Journal of Chromatography A (article, 2023-09-04)
Field: Chemistry — Spectroscopy

On the apparent dispersion coefficient of the equilibrium dispersion model: An asymptotic analysis To model chromatography, researchers have developed several approaches. These cover a broad range of applications and, depending on the assumptions adopted, have different levels of accuracy. In general, the most suitable modelling approach is the simplest that can describe a process with the desired accuracy. A model that often meets this criterion is the equilibrium dispersion model (EDM). This features one mass balance equation per analyte, including an axial dispersion term, and assumes the analyte concentrations in the mobile and stationary phases to be in local equilibrium. To account for the finite mass transfer rate between the phases, the model employs an apparent dispersion coefficient. Two expressions are available for this coefficient, one being used much more frequently than the other. In this paper, we aimed to clarify which one should be favoured. A desirable feature of simple models is that they can be derived from more general ones with appropriate physical assumptions and rigorous mathematical methods. Thus, to answer our research question, we derived the EDM from the more general pore diffusion model (POR), using an asymptotic method. The expression obtained for the apparent dispersion coefficient does agree with one of the two reported in the literature - the less frequently used. To test the validity of this expression, we simulated elution profiles using the two versions of the EDM and compared the results against those from the POR model. The simulations were conducted in the range where the POR and EDM models should be essentially equivalent, their results confirming the outcome of the asymptotic analysis. This work offers a solid theoretical grounding for the EDM, clarifies which formulation of the model is correct, and provides usable applicability conditions for the model. Dispersion (optics) ; Chemistry ; Applied mathematics ; Expression (computer science) ; Range (aeronautics) ; Diffusion ; Analyte ; Statistical physics ; Mechanics ; Statistics ; Thermodynamics ; Mathematics ; Chromatography ; Physics ; Computer science ; Optics ; Materials science Analytical Chemistry and Chromatography ; Protein purification and stability ; Microfluidic and Capillary Electrophoresis Applications
Authors: Malavika Kayyil Veedu | Julia Osmólska | Agata Hajda | Joanna Olesiak‐Bańska | Jérôme Wenger
Source: Nanoscale Advances (article, 2023-12-04)
Field: Materials Science — Materials Chemistry

Unveiling the photoluminescence dynamics of gold nanoclusters with fluorescence correlation spectroscopy Gold nanoclusters (AuNCs) have captured significant interest for their photoluminescent properties; however, their rapid photodynamics remain elusive while probed by ensemble-averaging spectroscopy techniques. To address this challenge, we use fluorescence correlation spectroscopy (FCS) to uncover the photoluminescence dynamics of colloidal Au<sub>18</sub>(SG)<sub>14</sub> nanoclusters. Our FCS analysis reveals the photoluminescence (PL) brightness per nanocluster, elucidating the impact of photoexcitation saturation and ligand interactions. Unlike DNA-encapsulated silver nanoclusters, their gold counterparts notably exhibit minimal blinking, with moderate amplitudes and 200 μs characteristic times. Our data also clearly reveal the occurrence of photon antibunching in the PL emission, showcasing the quantum nature of the PL process, with each AuNC acting as an individual quantum source. Using zero-mode waveguide nanoapertures, we achieve a 16-fold enhancement of the PL brightness of individual AuNCs. This constitutes an important enabling proof-of-concept for tailoring emission properties through nanophotonics. Overall, our study bridges the gap between ensemble-averaged techniques and single-molecule spectroscopy, offering new insights into AuNC photodynamics for biosensing and imaging applications. Nanoclusters ; Photoluminescence ; Photoexcitation ; Spectroscopy ; Fluorescence ; Materials science ; Brightness ; Quantum yield ; Quantum dot ; Photobleaching ; Chemical physics ; Fluorescence spectroscopy ; Nanotechnology ; Nanophotonics ; Photochemistry ; Optoelectronics ; Chemistry ; Physics ; Optics ; Atomic physics ; Excited state Nanocluster Synthesis and Applications ; Gold and Silver Nanoparticles Synthesis and Applications ; Carbon and Quantum Dots Applications