jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Fateme Poorsharbaf Ghavi | Fereshteh Raouf | Ahmad Dadvand Koohi
Source: Journal of Water and Health (article, 2020-12-29)
Field: Chemistry — Spectroscopy

The effect of alkaline pretreatment on surfactant-modified clinoptilolite for diclofenac adsorption: isotherm, kinetic, and thermodynamic studies Abstract The elimination of diclofenac traces from aqueous environments is important. In this research, the effect of alkaline (NaOH) pretreatment on clinoptilolite before its modification with a surfactant (HDTMA) for diclofenac adsorption under the speculation of the sole presence of diclofenac in the aqueous solution is investigated. The results are compared through isotherm, kinetic, and thermodynamic studies and supplemented by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET), and the zeta potential analyses. The contact time was investigated in a 0–180-min range. The pH effect was studied in a range of 5–10 because of diclofenac dissociation below pH = 5. The effect of the temperature on diclofenac adsorption was also considered by establishing the experiments at 25, 35, and 45 °C. For HDTMA-modified clinoptilolite, Temkin, and for NaOH-HDTMA-modified clinoptilolite, Dubinin–Radushkevich, and Freundlich isotherm models and in both cases, the pseudo-second-order kinetic model fitted the experimental data best. All the enthalpy and the entropy changes were negative, suggesting exothermic adsorption with a decrease in the degree of freedom of diclofenac anions after the adsorption. Furthermore, diclofenac physisorption was confirmed through isotherm and kinetic studies. Clinoptilolite ; Chemistry ; Freundlich equation ; Adsorption ; Enthalpy ; Aqueous solution ; Fourier transform infrared spectroscopy ; Pulmonary surfactant ; Diclofenac ; Physisorption ; Inorganic chemistry ; Langmuir ; Nuclear chemistry ; Langmuir adsorption model ; Organic chemistry ; Zeolite ; Chemical engineering ; Thermodynamics ; Catalysis ; Biochemistry Analytical Chemistry and Chromatography ; Analytical chemistry methods development ; Electrochemical Analysis and Applications
Authors: Joelle T. Reiser | Joseph V. Ryan | Marc H. Weber | Ján Ilavský | Matthew J. Olszta | Daniel K. Schreiber | Nathalie A. Wall
Source: npj Materials Degradation (article, 2020-02-21)
Field: Materials Science — Ceramics and Composites

Comparative structural investigations of nuclear waste glass alteration layers and sol-gel synthesized aerogels Abstract While various glass alteration layer formation mechanisms have been debated in recent years, the glass alteration community generally agrees that more information on physical properties of the alteration layers is needed to further the understanding of their impacts on overall glass alteration. In this work, pore volumes and solid structures of glass (International Simple Glass, ISG) alteration layers formed in solutions of various pH conditions in initially dilute conditions at 90 °C are evaluated with positron annihilation spectroscopy, small-angle X-ray scattering, and scanning transmission electron microscopy. Pore volumes of alteration layers formed at pH 9 were found to be at their lowest near the surfaces of the alteration layers. Solid structures of alteration layers are compared with those of synthetic aerogels of comparable compositions produced under various pH conditions. Alteration layers formed at pH 11 on ISG were shown to contain large structures (&gt;10 nm) similar to synthetic aerogels created under neutral and basic conditions whereas alteration layers formed at pH 9 did not. Available dissolved silica species defined by silica solubility were proposed to have the greatest impact on alteration layer structure. Chemical engineering ; Materials science ; Transmission electron microscopy ; Layer (electronics) ; Solubility ; Scanning electron microscope ; Mineralogy ; Chemistry ; Composite material ; Nanotechnology ; Organic chemistry Glass properties and applications ; Muon and positron interactions and applications ; Nuclear materials and radiation effects
Authors: Ghzzai Almutairi
Source: Energy Transitions (article, 2020-11-12)
Field: Materials Science — Materials Chemistry

A simple model for solid oxide fuel cells Abstract It is widely accepted that solid oxide fuel cells (SOFCs) represent a promising energy conversion approach that deliver a myriad of benefits including low environment pollution, high efficiency, and system compactness. This paper describes the construction of a basic model based on ohmic considerations, mass transfer, and kinetics that can effectively evaluate the performance of small button SOFCs. The analysis of the data indicates that there is a close alignment between the cell potential calculated using the model and previous experimental data. As such, it can be concluded that the model can be employed to optimize, evaluate, or control the design parameters within a SOFC system. Solid oxide fuel cell ; Fuel cells ; Oxide ; Computer science ; Ohmic contact ; Simple (philosophy) ; Energy transformation ; Process engineering ; Materials science ; Nanotechnology ; Engineering ; Chemical engineering ; Chemistry ; Thermodynamics Advancements in Solid Oxide Fuel Cells ; Electronic and Structural Properties of Oxides ; Catalysis and Oxidation Reactions
Authors: Alberto Adán-Más | Maryna Taryba | Teresa M. Silva | Liliane Guerlou‐Demourgues | M.F. Montemor
Source: Journal of The Electrochemical Society (article, 2020-01-05)
Field: Materials Science — Polymers and Plastics

In-Situ Localized pH, pNa and Dissolved O<sub>2</sub> Measurements During Charge-Discharge of Mixed Ni–Co Hydroxide Electrodes This work reports, for the first time, the use of ion-selective localized electrochemical techniques to elucidate the charge-discharge mechanism of nickel-cobalt hydroxide electrodes for electrochemical energy storage. The charge-discharge mechanism of electrodeposited nickel-cobalt hydroxide electrodes was studied in Na 2 SO 4 0.05 M by localized in situ measurements of pH, pNa and dissolved O 2 during cyclic voltammetry. Local pH and pNa distributions were recorded using micro-potentiometric sensors with liquid membrane, while dissolved O 2 was monitored using a fiber-optic microsensor. These original results highlight how localized potentiometry can provide new insights to better understand the charge mechanism of metal (hydr)oxide electrodes by directly measuring the concentrations/activities of relevant species at the electrode-electrolyte interface during charge-discharge. Potentiometric titration ; Hydroxide ; Electrode ; Electrochemistry ; Electrolyte ; Nickel ; Inorganic chemistry ; Cyclic voltammetry ; Cobalt ; Chemistry ; Analytical Chemistry (journal) ; Cobalt hydroxide ; Cobalt oxide ; Sodium hydroxide ; Chromatography Conducting polymers and applications ; Supercapacitor Materials and Fabrication ; Advanced battery technologies research
Authors: Kristýna Kantnerová | Malte Frydenlund Jespersen | Stefano M. Bernasconi | Lukas Emmenegger | Matthew S. Johnson | Joachim Mohn
Source: Atmospheric Environment X (article, 2020-10-09)
Field: Chemistry — Spectroscopy

Photolytic fractionation of seven singly and doubly substituted nitrous oxide isotopocules measured by quantum cascade laser absorption spectroscopy There is strong interest in using isotopic analysis to better constrain the budget of atmospheric nitrous oxide (N2O). This interest is supported by emerging instruments that allow analysis of multiply substituted species. We have studied fractionation during UV photolysis of singly and doubly isotopically substituted molecules (isotopocules) of N2O. N2O was photolyzed in an electropolished stainless-steel reactor using a broadband laser-driven light source with bandpass filters. Isotopocule ratios were quantified at different stages of photolysis using a quantum cascade laser absorption spectroscopy (QCLAS) system. Wavelength-dependent fractionation constants were determined using the Rayleigh distillation model. The fractionation constants for photolysis with 200 nm and 214 nm bandpass filters, respectively, for the seven most abundant isotopocules of N2O (after 14N14N16O) are: 14N15N16O (456): (−48.9 ± 7.4) ‰ /(−82.4 ± 22.3) ‰, 15N14N16O (546): (−22.2 ± 5.3) ‰ /(−36.1 ± 19.6) ‰, 14N14N17O (447): (−12.7 ± 4.5) ‰ /(−21.9 ± 15.7) ‰, 14N14N18O (448): (−33.5 ± 12.0) ‰ /(−44.1 ± 29.8) ‰, 14N15N18O (458): (−80.9 ± 6.5) ‰ /(−120.9 ± 23.7) ‰, 15N14N18O (548): (−52.7 ± 10.8) ‰ /(−79.1 ± 28.5) ‰, 15N15N16O (556): (−66.9 ± 9.8) ‰ /(−110.9 ± 27.5) ‰. The fractionation constants determined here for isotopocules 456, 546, 447, 448, and 556 are in agreement with previous theoretical models employed in this study and previous experiments. For 458 and 548, the fractionation constants were determined for the first time, confirming the prediction of more negative fractionation for 15N substitution in the central position. The effect of stratospheric photolysis on the clumped isotope Δ values of tropospheric N2O was found to be modest with Δ458 = (4.0 ± 1.0) ‰, Δ548 = (−4.0 ± 1.0) ‰, and Δ556 = (−1.5 ± 1.0) ‰ at 9% photolysis. Therefore, atmospheric variations of doubly substituted N2O isotopocules will likely be dominated by the characteristics of the N2O sources, which strongly supports their value for source attribution and quantification. Fractionation ; Photodissociation ; Chemistry ; Analytical Chemistry (journal) ; Mass-independent fractionation ; Spectroscopy ; Absorption (acoustics) ; Isotope fractionation ; Photochemistry ; Materials science ; Chromatography Spectroscopy and Laser Applications ; Atmospheric Ozone and Climate ; Atmospheric and Environmental Gas Dynamics
Authors: Fuqiang Yang | Wen-juan Zhan | Tao Yan | Haibing Zhang | Xiurong Fang
Source: Mathematical Problems in Engineering (article, 2020-04-25)
Field: Materials Science — Metals and Alloys

Numerical Analysis of the Coupling between Hydrogen Diffusion and Mechanical Behavior near the Crack Tip of Titanium Hydrogen plays a detrimental effect on the degeneration of titanium and its alloys, and it is very important to quantify the hydrogen concentration when estimating the microstructure evaluation of titanium and its alloys in a hydrogen environment. In this paper, the hydrogen atoms are assumed to reside in interstitial sites and in trapping sites such as dislocations, and a mechanic-diffusion coupled model was proposed to describe the stress effects on the diffusion of hydrogen in titanium. A titanium plate with a central crack was modeled to verify the mechanic-diffusion model, and it is solved by the finite element method in commercial software COMSOL. The results indicate that hydrogen diffusion near the crack is determined by the stress state. When the stress state of the crack tip is elastic, the hydrogen will diffuse from both sides of the crack towards the tip and lead to the highest hydrogen concentration in the crack tip. When a plastic zone exists in front of the crack tip, the highest hydrogen concentration at crack surface deviates to the side near the crack tip; a hydrogen concentration peak exists at a characterized distance in front of crack tip initially and then diminishes with the diffusion process. The proposed model is expected to solve the hydrogen concentration under stress in more complex structures. Hydrogen ; Materials science ; Diffusion ; Titanium ; Stress (linguistics) ; Titanium alloy ; Crack closure ; Diffusion process ; Composite material ; Fracture mechanics ; Metallurgy ; Forensic engineering ; Mechanics ; Thermodynamics ; Chemistry ; Physics Hydrogen embrittlement and corrosion behaviors in metals ; Nuclear Materials and Properties ; Fusion materials and technologies
Authors: T. Toyama | Miyuki Yajima | N. Ohno | T. Kuwabara | V.Kh. Alimov | Yuji Hatano
Source: Plasma and Fusion Research (article, 2020-11-19)
Field: Materials Science — Materials Chemistry

Dynamics of Hydrogen Isotope Absorption and Emission of Neutron-Irradiated Tungsten This overview presents recent results regarding hydrogen isotope absorption and emission dynamics in neutron-irradiated tungsten (W) using our recently developed Compact Diverter Plasma Simulator (CDPS), a linear plasma device in a radiation-controlled area. Neutron irradiation to 0.016 - 0.06 displacement per atom resulted in a significant increase in deuterium (D) retention due to trapping effects of radiation-induced defects. We analyzed the dependency of D retention on the D plasma fluence by exposing neutron-irradiated pure W to D plasma at 563 K over a range of D fluence values. The total retention was revealed to be proportional to the square root of D fluence, indicating that the implanted D atoms first occupy the defects caused by neutron-irradiation near the surface and then the defects located in deeper regions. We further investigated the effects of post-plasma annealing on D emission; neutron-irradiated pure W was exposed to D plasma at 573 K and was then annealed at the same temperature for 30 hours. Approximately 10% of the absorbed D was released by annealing, suggesting that a heat treatment of the plasma-facing component of a fusion reactor at moderately elevated temperatures could contribute to the removal of accumulated hydrogen isotopes. The experimental results obtained in this study were only available by investigating neutron-irradiated specimens with the CDPS system, which will be essential for future studies of material behavior and plasma-wall interactions in the fusion reactor environment. Materials science ; Irradiation ; Fluence ; Tungsten ; Neutron ; Plasma ; Hydrogen ; Neutron flux ; Deuterium ; Radiochemistry ; Annealing (glass) ; Analytical Chemistry (journal) ; Atomic physics ; Nuclear physics ; Chemistry ; Physics ; Composite material Fusion materials and technologies ; Nuclear Materials and Properties ; Metal and Thin Film Mechanics
Authors: A. C. Garcia‐Castro | Philippe Ghosez | Éric Bousquet | A. Romero
Source: Physical review. B./Physical review. B (article, 2020-12-17)
Field: Materials Science — Materials Chemistry

Oxyfluoride superlattices <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi mathvariant="normal">K</mml:mi><mml:mi>Ta</mml:mi><mml:msub><mml:mrow><mml:mi mathvariant="normal">O</mml:mi></mml:mrow><mml:mn>3</mml:mn></mml:msub><mml:mo>/</mml:mo><mml:mi mathvariant="normal">K</mml:mi><mml:mi>M</mml:mi><mml:msub><mml:mrow><mml:mi mathvariant="normal">F</mml:mi></mml:mrow><mml:mn>3</mml:mn></mml:msub></mml:math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mo>(</mml:mo><mml:mi>M</mml:mi><mml:mo>=</mml:mo><mml:mi>Zn</mml:mi><mml:mo>,</mml:mo><mml:mi>Ni</mml:mi><mml:mo>)</mml:mo></mml:math>: Structural and electronic phenomena The structural and electronic properties of ${\mathrm{KTaO}}_{3}$/${\mathrm{KZnF}}_{3}$ and ${\mathrm{KTaO}}_{3}$/${\mathrm{KNiF}}_{3}$ oxyfluoride superlattices are studied from first-principles density functional theory calculations. We highlight, that beyond a critical layer thickness, these systems exhibit an insulator to metal transition that gives rise to the appearance of two-dimensional electron and hole gas, confined both, due the band alignment, within the oxide layer. The origin of the insulator to metal transition is related to the polar discontinuity at the interfaces. The behavior is discussed in terms of a simple electrostatic model and compared to that of the prototypical ${\mathrm{LaAlO}}_{3}$/${\mathrm{SrTiO}}_{3}$ oxide system. The magnetic properties ${\mathrm{KTaO}}_{3}$/${\mathrm{KNiF}}_{3}$ superlattices are further discussed, revealing a sizable Rashba-type spin splitting at these interfaces, much larger than in similar oxide/oxide systems. Superlattice ; Condensed matter physics ; Materials science ; Oxide ; Discontinuity (linguistics) ; Crystallography ; Physics ; Chemistry ; Mathematics Electronic and Structural Properties of Oxides ; Magnetic and transport properties of perovskites and related materials ; Advanced Condensed Matter Physics
Authors: Maha S. Almutairi | Areej N. Al Suwayyid | Amal Aldarwesh | Omaima M. Aboulwafa | Mohamed I. Attia
Source: Molecules (article, 2020-03-28)
Field: Chemistry — Organic Chemistry

Antiestrogenic Activity and Possible Mode of Action of Certain New Nonsteroidal Coumarin-4-acetamides The preparation of certain 2-(2-oxo-2<i>H</i>-chromen-4-yl)-<i>N</i>-substituted acetamides <b>IIIa-h</b> was planned as a step in the development of new modified nonsteroidal antiestrogens. The purity of target compounds <b>IIIa-h</b> was checked by thin-layer chromatography (TLC), and their structures were confirmed using various spectroscopic tools including IR, <sup>1</sup>H-NMR, <sup>13</sup>C-NMR, and MS spectroscopy. Viability tests were applied using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay to evaluate the cytotoxic effect of the synthesized compounds against two breast cancer cell lines, MCF-7 and MDA-MB-231. Compound <b>IIIb</b> proved the most active against MCF-7 cells, with an IC<sub>50</sub> value of 0.32 μM. The results of an analysis of in vitro antiestrogenic activity indicated that only compound <b>IIIb</b> exhibited antiestrogenic activity; its IC<sub>50</sub> value of 29.49 μM was about twice as potent as that of the reference compound, MIBP. The aromatase activity was evaluated for the synthesized target compounds <b>IIIa-g</b> and the intermediates <b>Ib</b> and <b>IIa</b>. A significant aromatase inhibition was observed for the intermediate <b>Ib</b> and compound <b>IIIe</b>, with IC<sub>50</sub> values of 14.5 and 17.4 μM, respectively. Compound <b>IIIb</b>, namely 7-methoxy-4-(2-oxo-2-(piperidin-1-yl)ethyl)-2H-chromen-2-one, could be used as an antiestrogen and/or cytotoxic agent with selective activity against tumor cells. Coumarin ; Nonsteroidal ; Mode of action ; Action (physics) ; Pharmacology ; Chemistry ; Medicine ; Biochemistry ; Organic chemistry ; Physics Free Radicals and Antioxidants ; Synthesis and biological activity ; bioluminescence and chemiluminescence research
Authors: Badr Malek | İmane BAHAMMOU | Omar Zimou | Achraf El Hallaoui | Rachida Ghaılane | Saı̈d Boukhris | Abdelaziz Souızı
Source: Journal of the Turkish Chemical Society Section A Chemistry (article, 2020-04-25)
Field: Chemistry — Organic Chemistry

Eco-friendly Synthesis of Quinoxaline Derivatives Using Mineral Fertilizers as Heterogeneous Catalysts The synthesis of quinoxaline derivatives were heterogeneously catalyzed by phosphate-based catalyst fertilizers, MAP, DAP, or TSP. The reaction affords the desired products in excellent yields at ambient temperature. A series of studies were conducted to investigate the effect of solvent reaction, its volume, and catalyst amount. A study of the recyclability of catalysts removed from the reaction mixture by simple filtration was also carried out to find that the three phosphate-based catalysts retain their catalytic activities up to six cycles. Catalysis ; Quinoxaline ; Chemistry ; Filtration (mathematics) ; Solvent ; Organic chemistry ; Phosphate ; Reaction conditions ; Mathematics Synthesis and Biological Evaluation
Authors: Carmen Creţu | Loredana Maiuolo | Domenico Lombardo | Elisabeta I. Szerb | Pietro Calandra
Source: Journal of Nanomaterials (article, 2020-10-13)
Field: Materials Science — Biomaterials

Luminescent Supramolecular Nano- or Microstructures Formed in Aqueous Media by Amphiphile-Noble Metal Complexes The involvement of metal ions within the self-assembly spontaneously occurring in surfactant-based systems gives additional and interesting features. The electronic states of the metal, together with the bonds that can be established with the organic amphiphilic counterpart, are the factors triggering new photophysical properties. Moreover, the availability of stimuli-responsive supramolecular amphiphile assemblies, able to disassemble in a back-process, provides reversible switching particularly useful in novel approaches and applications giving rise to truly smart materials. In particular, small amphiphiles with an inner distribution, within their molecular architecture, of various polar and apolar functional groups, can give a wide variety of interactions and therefore enriched self-assemblies. If it is joined with the opportune presence and localization of noble metals, whose chemical and photophysical properties are undiscussed, then very interesting materials can be obtained. In this minireview, the basic concepts on self-assembly of small amphiphilic molecules with noble metals are shown with particular reference to the photophysical properties aiming at furnishing to the reader a panoramic view of these exciting problematics. In this respect, the following will be shown: (i) the principles of self-assembly of amphiphiles that involve noble metals, (ii) examples of amphiphiles and amphiphile-noble metal systems as representatives of systems with enhanced photophysical properties, and (iii) final comments and perspectives with some examples of modern applications. Amphiphile ; Supramolecular chemistry ; Noble metal ; Materials science ; Nanotechnology ; Self-assembly ; Molecule ; Metal ; Copolymer ; Chemistry ; Organic chemistry ; Polymer Supramolecular Self-Assembly in Materials ; Metal-Organic Frameworks: Synthesis and Applications ; Supramolecular Chemistry and Complexes
Authors: Veronika Zeindlhofer | Phillip S. Hudson | Ádám Márk Pálvölgyi | Matthias Welsch | Mazin Almarashi | H. Lee Woodcock | Bernard R. Brooks | Katharina Bica | Christian Schröder
Source: International Journal of Molecular Sciences (article, 2020-08-28)
Field: Chemistry — Spectroscopy

Enantiomerization of Axially Chiral Biphenyls: Polarizable MD Simulations in Water and Butylmethylether In this study, we investigate the influence of chiral and achiral cations on the enantiomerization of biphenylic anions in <i>n</i>-butylmethylether and water. In addition to the impact of the cations and solvent molecules on the free energy profile of rotation, we also explore if chirality transfer between a chiral cation and the biphenylic anion is possible, i.e., if pairing with a chiral cation can energetically favour one conformer of the anion via diastereomeric complex formation. The quantum-mechanical calculations are accompanied by polarizable MD simulations using umbrella sampling to study the impact of solvents of different polarity in more detail. We also discuss how accurate polarizable force fields for biphenylic anions can be constructed from quantum-mechanical reference data. Polarizability ; Umbrella sampling ; Chemistry ; Chirality (physics) ; Diastereomer ; Polarizable continuum model ; Conformational isomerism ; Computational chemistry ; Pairing ; Molecular dynamics ; Chemical physics ; Quantum ; Ion ; Molecule ; Solvent ; Interaction energy ; Solvent effects ; Stereochemistry ; Physics ; Organic chemistry ; Quantum mechanics Molecular spectroscopy and chirality ; Advanced NMR Techniques and Applications ; Crystallography and molecular interactions