jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Christopher M. Bottoms | Tanguy Terlier | Gila E. Stein | Manolis Doxastakis
Source:  (article, 2021-02-19)
Field: Materials Science — Materials Chemistry

Probing ion diffusion in chemically amplified resists through experiments and atomistic simulations Catalyst diffusion is a critical component of the pattern formation process in chemically amplified resists (CARs). In this study, we used a concerted experimental and modeling effort to examine diffusion of an inert catalyst analogue (sodium triflate) in a hydroxystyrene-based ESCAP terpolymer resin. First, atomistic simulations at high temperatures reveal an order-of-magnitude enhancement of the Fickian diffusivity in the protected reactant versus the fully deprotected product, while time-of-flight secondary ion mass spectrometry (TOF-SIMS) measurements at temperatures near the glass transition show no appreciable differences. The data from simulations and experiments conform to a unified curve, enabling estimates of the Fickian diffusivity at relevant post-exposure bake (PEB) temperatures through extrapolation. Second, acid-catalyzed reaction kinetics were measured with Fourier-transform infrared spectroscopy and compared with reaction-diffusion models based on the estimated Fickian diffusivities. The initial kinetics in experiments is orders-of-magnitude faster than predictions, demonstrating that models of catalyst transport should capture effects beyond Fickian diffusion. Finally, the simulations examined ion-ion and polymer-ion interactions at the atomistic level, features that are difficult to probe by experimental investigations. These data show that ion pair clustering in the protected and deprotected materials is similar as temperature is reduced, and ion pair dynamics in both materials is dominated by interactions with hydroxystyrene repeat units. These trends explain the experimental observations that ion diffusion is similar in the protected and deprotected polymers. Fick's laws of diffusion ; Diffusion ; Thermal diffusivity ; Ion ; Chemistry ; Chemical physics ; Analytical Chemistry (journal) ; Materials science ; Thermodynamics ; Organic chemistry Block Copolymer Self-Assembly ; Advancements in Photolithography Techniques ; Ion-surface interactions and analysis
Authors: Amit K. Thakur | Rahul Kumar | Nilanjana Banerjee | Pranava Chaudhari | Amit Kumar
Source: Materials Today Proceedings (article, 2021-12-01)
Field: Chemistry — Organic Chemistry

Simulation of ethylene polymerization in continuous slurry reactors Continuous stirred-tank reactor ; Polymerization ; Dispersity ; Materials science ; Polyethylene ; Slurry ; Chemical engineering ; Monomer ; Polymer ; Yield (engineering) ; Diffusion ; Mass transfer ; Particle (ecology) ; Continuous reactor ; Polymer chemistry ; Catalysis ; Thermodynamics ; Chemistry ; Chromatography ; Organic chemistry ; Composite material Advanced Polymer Synthesis and Characterization ; Organometallic Complex Synthesis and Catalysis ; biodegradable polymer synthesis and properties
Authors: Temilolu J. Popoola | Afamefuna Elvis Okoronkwo | Olugbenga Oludayo Oluwasina | Matthew A. Adebayo
Source: Research Square (preprint, 2021-02-08)
Field: Chemistry — Organic Chemistry

Preparation, Characterization and Application of a Home–made Graphene for the Removal of Congo Red From Aqueous Solutions Congo red ; Graphene ; Characterization (materials science) ; Aqueous solution ; Materials science ; Nanotechnology ; Chemical engineering ; Polymer science ; Chemistry ; Engineering ; Organic chemistry ; Adsorption Nanomaterials for catalytic reactions ; Graphene and Nanomaterials Applications ; Dye analysis and toxicity
Authors: Giulio Antunes de Medeiros | Leonardo Martins da Silva | Márcio Teodoro Fernandes | Daniel Gomes de Souza dos Santos | José Adílson de Castro
Source: Materials Research (article, 2021-01-01)
Field: Chemistry — Organic Chemistry

Analysis of the Carbothermic Reduction of Iron Ore-Coke Composite Mixtures by Microwave Heating In recent decades, microwave energy has been successfully experimented for mining and metallurgy processes and is considered a promising new method for ironmaking. In this context, in the present work, self-reducing mixtures composed of fines of iron ore and coke were prepared, intending to evaluate the degree of reduction of iron ore using microwave energy, applying different contents of coke, levels of power, and reaction times. For this, the degree of reduction was assessed as a function of these variables. Additionally, the reduction kinetics was investigated using chemical and diffusional models, and the microstructure of the samples was evaluated using scanning electron microscopy (SEM). The highest degree of reduction obtained after the experiments was greater than 60% and a statistical investigation showed that the reaction time is the factor with the greatest influence on these results, followed by microwave power and coke content. The investigation of the reaction kinetics showed that the process is chemically controlled, depending on the gasification steps governed by the Boudouard reaction. The images obtained by SEM led to the conclusion that the temperature inside the sample reached 1200C. Pig iron was found both in the form of whiskers and in the form of metallic droplets. Coke ; Iron ore ; Pig iron ; Materials science ; Metallurgy ; Scanning electron microscope ; Microstructure ; Microwave ; Whiskers ; Context (archaeology) ; Kinetics ; Petroleum coke ; Chemical engineering ; Composite material Microwave-Assisted Synthesis and Applications ; Advanced materials and composites ; Metal Extraction and Bioleaching
Authors: Yao-Hsuan Lai | Jin-Chun Lim | Ya-Chu Lee | Jian‐Jang Huang
Source: ACS Omega (article, 2021-04-02)
Field: Chemistry — Electrochemistry

Analysis of the Biochemical Reaction Status by Real-Time Monitoring Molecular Diffusion Behaviors Using a Transistor Biosensor Integrated with a Microfluidic Channel Traditional methods of monitoring biochemical reactions measure certain detectable reagents or products while assuming that the undetectable species follow the stoichiometry of the reactions. Here, based upon the metal-oxide thin-film transistor (TFT) biosensor, we develop a real-time molecular diffusion model to benchmark the concentration of the reagents and products. Using the nicotinamide adenine dinucleotide (NADH)-oxaloacetic acid with the enzyme of malate dehydrogenase as an example, mixtures of different reagent concentrations were characterized to extract the ratio of remaining concentrations between NAD<sup>+</sup> and NADH. We can thus obtain the apparent equilibrium constant of the reaction, (8.06 ± 0.61) × 10<sup>4</sup>. Because the whole analysis was conducted using a TFT sensor fabricated using a semiconductor process, our approach has the advantages of exploring biochemical reaction kinetics in a massively parallel manner. Reagent ; Biosensor ; Chemistry ; Diffusion ; Nicotinamide adenine dinucleotide ; Transistor ; Microfluidics ; Stoichiometry ; NAD+ kinase ; Materials science ; Combinatorial chemistry ; Analytical Chemistry (journal) ; Nanotechnology ; Chromatography ; Enzyme ; Biochemistry ; Physical chemistry Electrochemical Analysis and Applications ; Analytical Chemistry and Sensors ; Innovative Microfluidic and Catalytic Techniques Innovation
Authors: Palash Mishra | Moutusi Paul | Shubham Mishra
Source:  (article, 2021-12-03)
Field: Materials Science — Materials Chemistry

Understanding the Liquid Permeation Properties ot RTV Silicone Rubber Nanocomposites Subjected to Strong Electrolytic Solutions Room temperature vulcanized (RTV) silicone rubber (SiR) has been demonstrated to be the most effective hydrophobic coating material for augmenting the pollution performance of outdoor high voltage (HV) ceramic insulators. However, water/liquid ingress severely degrades the material properties of SiR. Therefore, the proposed work investigates the liquid immersion/permeation resistance of Silica (SiO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> ) and Titania (TiO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> ) doped RTV SiR nanocomposites through weight-gain experiments performed at room temperature of 27°C. The test was performed with the SiR nanocomposites exposed to deionized water (DI) and strong electrolytic sodium chloride (NaCl) and nitric acid (HNO3) solution. The diffusion rate for each test configuration was numerically investigated using the Fickian diffusion model. Investigation results propose that the permeation resistance of SiR amalgamates depend upon the solution and the nanofiller type. Further, depending upon the test observations, RTV SiR nanocomposite with higher degradation resistance against strong electrolytic solutions is identified and reported. Permeation ; Vulcanization ; Materials science ; Silicone rubber ; Nanocomposite ; Electrolyte ; Chemical engineering ; Composite material ; Nitric acid ; Natural rubber ; Membrane ; Chemistry ; Metallurgy High voltage insulation and dielectric phenomena ; Dielectric materials and actuators ; Power Transformer Diagnostics and Insulation
Authors: Princy Philip | Tomlal Jose | Jomit T. Mathew | Jinesh M. Kuthanapillil
Source: Nano Futures (article, 2021-04-09)
Field: Materials Science — Biomaterials

Multilayer adsorption and kinetic studies of dyes on pure and structurally modified poly(methyl methacrylate) electrospun nanofibers Abstract Natural fibers and materials are well known for adsorption studies, whereas synthetic fibers have not received enough attention in this field. Therefore, an attempt is made here to study the adsorption properties of synthetic poly(methyl methacrylate) (PMMA) nanofibers and methods for improving or modifying their adsorption properties. PMMA nanofibers are prepared by the most recent electrospinning technique and the structural, and hence, the adsorption properties of the PMMA nanofibers are modified by preparing them in surface-roughened and coaxial hollow forms through electrospinning. Studies of the adsorption of methylene blue (MB) and brilliant green (BG) dyes by the three types of PMMA nanofiber demonstrate that all the PMMA nanofibers show a certain amount of adsorption. Fiber samples that had adsorbed MB and BG were subjected to various adsorption isotherms which confirmed the multilayer adsorption properties of the fiber samples by satisfying various isotherms, mainly the Freundlich and Elovich adsorption isotherms. Kinetic studies of pure and structurally modified PMMA nanofibers that had adsorbed MB and BG dyes proved that the intraparticle diffusion model applied to these fiber samples. Here, it is also shown that the adsorption properties of electrospun synthetic fibers can be further improved by structural modification using the possibilities of electrospinning. Adsorption ; Nanofiber ; Electrospinning ; Materials science ; Chemical engineering ; Freundlich equation ; Methyl methacrylate ; Synthetic fiber ; Fiber ; Poly(methyl methacrylate) ; Langmuir ; Polymer chemistry ; Composite material ; Polymer ; Organic chemistry ; Chemistry ; Polymerization Electrospun Nanofibers in Biomedical Applications ; Conducting polymers and applications ; Advanced Sensor and Energy Harvesting Materials
Authors: Jordon Hemingway | Gregory Henkes
Source: Goldschmidt2021 abstracts (article, 2021-01-01)
Field: Chemistry — Spectroscopy

A distributed activation energy model for clumped isotope bond reordering in carbonates Carbonate clumped isotopes (47) have become a widely applied method for paleothermometry, with applications spanning many environmental settings over hundreds of millions of years. However, 47-based paleothermometry can be complicated by closure temperature-like behavior whereby C-O bonds are reset at elevated diagenetic or metamorphic temperatures, sometimes without obvious mineral alteration. Laboratory studies have constrained this phenomenon by heating well-characterized materials at various temperatures, observing temporal 47 evolution, and fitting results to kinetic models with prescribed C-O bond reordering mechanisms. While informative, these models are inflexible regarding the nature of isotope exchange, leading to potential uncertainties when extrapolated to geologic timescales. Here, we instead propose that reordering kinetics arise naturally from random-walk 18O diffusion through the carbonate lattice, and we develop a "disordered" kinetic framework that treats C-O bond reordering as a continuum of first-order processes occurring in parallel at different rates. We show theoretically that all previous models are specific cases of disordered kinetics; thus, our approach reconciles the transient defect/equilibrium defect and paired reaction-diffusion models. We estimate the rate coefficient distributions from published heating experiment data by finding a regularized inverse solution that best fits each 47 timeseries. Importantly, this approach does not assume a particular mechanism or energy distribution a priori. Resulting distributions are well-approximated as lognormal for all experiments on calcite or dolomite; aragonite experiments require more complex distributions that are consistent with a change in oxygen bonding environment during the transition to calcite. Presuming lognormal rate coefficient distributions and Arrhenius-like temperature dependence yields an underlying activation energy, E, distribution that is Gaussian with a mean value of E = 224.327.6 kJmol-1 and a standard deviation of E = 17.40.7 kJmol-1 (1 uncertainty; n=24) for calcite and E = 230.347.7 kJmol-1 and E = 14.82.2 kJmol-1 (n=4) for dolomite. These model results are adaptable to other minerals and may provide a basis for future experiments whereby the nature of carbonate C-O bonds is altered (e.g., by inducing mechanical strain or cation substitution). Finally, we apply our results to geologically relevant heating/cooling histories and suggest that previous models underestimate low-temperature alteration but overestimate 47 blocking temperatures. Computer science ; Isotope ; Geology ; Parallel computing ; Physics ; Nuclear physics Advanced NMR Techniques and Applications ; Methane Hydrates and Related Phenomena ; High-pressure geophysics and materials
Authors: Mehmet Uğurlu | Hussien H. Osman | Ali İmran Vai̇zoğullar | Abdul J. Chaudhary
Source: International Journal of Engineering Science Technologies (article, 2021-04-11)
Field: Chemistry — Organic Chemistry

FLUOROQUINOLONES ANTIBIOTICS ADSORPTION ONTO POLYMER COATED MAGNETIC NANOPARTICULAR ACTIVATED CARBON The present study investigated the adsorption of molecular fluoroquinolone (FLQ) from aqueous solution onto active carbon (AC), magnetic activated carbon (MagAC), styrene-butadiene styrene magnetic activated carbon (SBS/MagAC) and poly charbon magnetic activated carbon (PC/MagAC) as adsorbent materials. The process optimization was carried by investigating the effects of pH, temperature, solid-liquid ratio, adsorbent type and initial concentration of FLQ. The data showed that adsorption reached equilibrium in as little as one hour. The adsorption cacapcity was comparatively less at low pH values than at approximately pH 5.0. The results also showed that the polymer coated magnetic materials did not perform very well at high pH values. However, all the materials performed well at room temperature when the situation was examined in terms of kinetics. It was also observed that AC, SBS/MagAC and PC/MagAC are more effective than MagAC to remove FLQ from aqueous medium. The kinetic data support pseudo-second-order model (r2 ⩾ 0.95) but showed very poor fit for pseudo-first-order model (r2 ≤ 0.90). Intra-particle model also showed that there were two separate stages in sorption process, namely, external diffusion and the diffusion of inter-particle. Adsorption isotherms for all adsorbends were fitted to Langmuire models more effectively than Freundlich models (r2 ⩾ 0.98). Thermodynamics parameters such as; free energy (ΔG0), enthalpy (ΔH0) and entropy (ΔS0) were also calculated. In conclusion, our results revealed that FLQ can be removed more easily from the aqueous medium by using magnetic and polymeric material. Adsorption ; Activated carbon ; Enthalpy ; Sorption ; Aqueous solution ; Freundlich equation ; Diffusion ; Chemistry ; Materials science ; Styrene-butadiene ; Polymer ; Particle size ; Chemical engineering ; Styrene ; Thermodynamics ; Organic chemistry ; Physical chemistry ; Copolymer ; Physics Nanomaterials for catalytic reactions ; Adsorption and biosorption for pollutant removal ; Pharmaceutical and Antibiotic Environmental Impacts
Authors: Nicolae Baranov | Ștefania Racoviță | Silvia Vasiliu | Ana‐Maria Macsim | Cătălina Lionte | Valeriu Şunel | Marcel Popa | Jacques Desbrières | Corina Cheptea
Source: Molecules (article, 2021-06-01)
Field: Chemistry — Organic Chemistry

Immobilization and Release Studies of Triazole Derivatives from Grafted Copolymer Based on Gellan-Carrying Betaine Units New polymer-bioactive compound systems were obtained by immobilization of triazole derivatives onto grafted copolymers and grafted copolymers carrying betaine units based on gellan and N-vinylimidazole. For preparation of bioactive compound, two new types of heterocyclic thio-derivatives with different substituents were combined in a single molecule to increase the selectivity of the biological action. The 5-aryl-amino-1,3,4 thiadiazole and 5-mercapto-1,2,4-triazole derivatives, each containing 2-mercapto-benzoxazole nucleus, were prepared by an intramolecular cyclization of thiosemicarbazides-1,4 disubstituted in acidic and basic medium. The structures of the new bioactive compounds were confirmed by elemental and spectral analysis (FT-IR and <sup>1</sup>H-NMR). The antimicrobial activity of 1,3,4 thiadiazoles and 1,2,4 triazoles was tested on gram-positive and gram-negative bacteria. The triazole compound was chosen to be immobilized onto polymeric particles by adsorption. The Langmuir, Freundlich, and Dubinin-Radushkevich adsorption isotherm were used to describe the adsorption equilibrium. Also, the pseudo-first and pseudo-second models were used to elucidate the adsorption mechanism of triazole onto grafted copolymer based on N-vinylimidazole and gellan (PG copolymer) and grafted copolymers carrying betaine units (PGB1 copolymer). In vitro release studies have shown that the release mechanism of triazole from PG and PGB1 copolymers is characteristic of an anomalous transport mechanism. Copolymer ; Betaine ; Chemistry ; Adsorption ; Triazole ; Freundlich equation ; Polymer chemistry ; Combinatorial chemistry ; Langmuir ; Polymer ; Organic chemistry Click Chemistry and Applications ; Biopolymer Synthesis and Applications ; Antimicrobial agents and applications
Authors: Ahmed M. Elbarbary | Yasser H. Gad
Source: Research Square (preprint, 2021-03-24)
Field: Materials Science — Polymers and Plastics

Radiation Synthesis and Characterization of Poly(Vinyl Alcohol)/ Acrylamide/ TiO2/ SiO2&amp;nbsp;Nanocomposite for Removal of Metal Ion and Dye From Waste Water Abstract An effective and novel adsorbent of poly(vinyl alcohol)/polyacrylamide/TiO 2 /SiO 2 (PVA-co-AAm/TiO 2 /SiO 2 ) nanocomposite synthesized by γ-irradiation polymerization of PVA and AAm in presence of TiO 2 /SiO 2 nanoparticles at different irradiation doses (10, 30 and 50 kGy) for removal of Cu(II) ions and basic blue 3 dye from their aqueous solutions. FT-IR, TEM, XRD, SEM, EDS and DLS analyzed the chemical properties of nanocomposites. The nanocomposite prepared at 30 kGy (PVA-co-AAm/TiO 2 /SiO 2 -30) shows high swelling of 197.7 (%) and gelation of 93.1 %. The adsorption capacity (mg/g) and removal (%) of basic blue 3 dye and Cu(II) ions onto nanocomposites by varying experimental conditions were investigated. The PVA-co-AAm/TiO 2 /SiO 2 -30 showed high adsorption capacity 3 folds rather than PVA-co-AAm. The equilibrium adsorption for basic blue 3 dye and Cu(II) was 123.9 mg/g and 190.3 mg/g with removal of 82.6 and 95.1 %, respectively. The results of the adsorption of dye or metal ions follow the Pseudo-second order adsorption kinetic, fit with the Langmuir isotherm and the adsorption process is endothermic and spontaneous in nature. The results revealed that the PVA-co-AAm/TiO 2 /SiO 2 nanocomposites could be employed as an effectual adsorbent for adsorption of basic blue dye and Cu(II) ions from wastewater with high adsorption capacity and recovery. Vinyl alcohol ; Adsorption ; Nanocomposite ; Langmuir adsorption model ; Aqueous solution ; Metal ions in aqueous solution ; Nuclear chemistry ; Materials science ; Endothermic process ; Chemical engineering ; Chemistry ; Polymer chemistry ; Metal ; Polymer ; Organic chemistry ; Composite material Polymer Nanocomposite Synthesis and Irradiation ; Graphene and Nanomaterials Applications ; Recycling and Waste Management Techniques
Authors: Stephen Peppin
Source:  (preprint, 2021-04-27)
Field: Materials Science — Materials Chemistry

Anomalous tracer diffusion in hard-sphere suspensions Coupled equations describing diffusion and cross-diffusion of tracer particles in hard-sphere suspensions are derived and solved numerically. In concentrated systems with strong excluded volume and viscous interactions the tracer motion is subdiffusive. Cross diffusion generates transient perturbations to the host-particle matrix, which affect the motion of the tracer particles leading to nonlinear mean squared displacements. Above a critical host-matrix concentration the tracers experience clustering and uphill diffusion, moving in opposition to their own concentration gradient. A linear stability analysis indicates that cross diffusion can lead to unstable concentration fluctuations in the suspension. The instability is a potential mechanism for the appearance of dynamic and structural heterogeneity in suspensions near the glass transition. TRACER ; Diffusion ; Instability ; Anomalous diffusion ; Particle (ecology) ; Suspension (topology) ; Nonlinear system ; Matrix (chemical analysis) ; Physics ; Classical mechanics ; Mechanics ; Chemistry ; Thermodynamics ; Mathematics ; Geology ; Chromatography ; Innovation diffusion Material Dynamics and Properties ; Granular flow and fluidized beds ; Theoretical and Computational Physics
Authors: Selmi Erim Bozbağ
Source: Turkish Journal of Engineering (article, 2021-10-27)
Field: Materials Science — Materials Chemistry

Single and multisite detailed kinetic models for the adsorption and desorption of NO2 over Cu based NH3-SCR catalyst Kinetic modeling of NH3 Selective Catalytic Reduction (NH3-SCR) of NOx in Cu-chabazite washcoated monolithic reactors has recently become an important task for design, control and calibration of heavy-duty engine aftertreatment systems. Development of detailed and accurate kinetic models rely on the correct simulation of the NO2 and NH3 storage at different conditions. Here, different kinetic schemes for NO2 adsorption and desorption were developed and compared to experimental data. For this purpose, firstly, realistic values of the active Cu sites in the Cu-zeolite were obtained using the temperature programmed desorption (TPD) of NH3 and NO2 which showed fractional coverages of 0.04 and 0.17 for the so-called ZCuOH and Z2Cu species which reside in the 8 and 6 membered rings (MR) of the zeolitic framework, respectively. Active site concentrations were used in the kinetic models which included simultaneous formation of nitrate/nitrite species or the formation of HNO3 intermediate which in turn resulted in the formation of nitrates or nitrites over the ZCuOH. Models also included or excluded the NO2 storage over the so called secondary Z2Cu sites. It was shown that models taking into account HNO3 intermediate formation along with two NO2 storage sites were better fits to the experimental data. Chabazite ; Desorption ; Catalysis ; Kinetic energy ; Adsorption ; Chemistry ; Selective catalytic reduction ; Nitrite ; Zeolite ; NOx ; Thermal desorption spectroscopy ; Chemical engineering ; Nitrate ; Physical chemistry ; Organic chemistry ; Combustion ; Physics Catalytic Processes in Materials Science ; Ammonia Synthesis and Nitrogen Reduction ; Nanomaterials for catalytic reactions