Constant Values Research Articles

Self-organization of Janus particles: Impact of hydrodynamic interactions in substrate consumption for structure formation.

We show that the formation of active matter structures requires them to modify their surroundings by creating inhomogeneities such as concentration gradients and fluid flow around the structure constituents. This modification is crucial for the stability of the ordered structures. We examine the formation of catalytic Janus particle aggregates at low volumetric fractions in the presence of hydrodynamic interactions (HIs). Our study shows the types of structures formed for various values of the kinetic constant of the catalytic reaction. The presence of HI causes the aggregate particles to have higher mobility than in the case of the absence of such interactions, which is reflected in the behavior of the pair distribution function. Although HI decreases energy conversion efficiency, they play a significant role in the formation of complex structures found in nature. Self-organization of these structures is driven by direct feedback loops between structure formation and the surrounding medium. As the structures alter the medium by consuming substrate and perturbing fluid flow, the substrate concentration, in turn, dictates the kinetics and configuration of the structures.

CHEMICAL TRANSFORMATIONS OF PYRROLO-1,5-BENZODIAZEPINE DERIVATIVES

One of the most important tasks in modern organic chemistry is search and development of simple synthesis methods and study of the chemical properties of new biologically active substances. Pyrrolo-1,5-benzodiazepine derivatives refer to an important class of nitrogen-containing heterocycles with a wide range of biological activities. Based on the structure of the synthesized 4,5-dihydropyrrolo[1,2,3-e,f][1,5]-benzodiazepin-6(7H)-ones, it can be concluded that they possess high reactivity towards chemical transformations. This work examines the chemical properties of these derivatives (hydrolysis, transesterification, restoration, alkylation, amidation) and evaluates the acid-base properties of pyrrolo-1,5-benzodiazepine derivatives. As a result of the research we obtained two values for ionization constants that correspond to the protonation of the amide group of the diazepine ring and the indole part of the molecule. Protonation of the amide group of the diazepine ring can occur either on the nitrogen atom or the oxygen atom. However, O-protonation is more likely. In this case the mesomeric bonding of the electron pair of nitrogen atom with π/r-electron sextet of the benzene ring is not disrupted. These data provide valuable information on the reliance of the biological activity of the compound on its chemical structure and its chemical properties. The prospects for studying the biological activity of synthesized pyrrolo-1,5-benzodiazepine derivatives for their further use in medical practice is demonstrated.

Thermodynamic aspects of the [3+2] cycloaddition reaction of triphenyl-substituted TACs and the ethyl oleate

The [3+2] cycloaddition reactions of triphenyl-substituted TACs and the ethyl oleate were examined on the basis of the DFT thermodynamic calculations. Free thermodynamic potentials of the reaction, values of the equilibrium constants K and equilibrium degrees were estimated on the basis of results derived from the vibrational analysis. Obtained results were compared with experimental studies on the model reaction with the participation of the C,C,N-triphenylnitrone.

Host–Guest Complexation of Olmesartan Medoxomil by Heptakis(2,6-di-O-methyl)-β-cyclodextrin: Compatibility Study with Excipients

Background: Olmesartan medoxomil (OLM) is the prodrug of olmesartan, an angiotensin II type 1 receptor blocker that has antihypertensive and antioxidant activities and renal protective properties. It exhibits low water solubility, which leads to poor bioavailability and limits its clinical potential. To improve the solubility of OLM, a host–guest inclusion complex (IC) between heptakis(2,6-di-O-methyl)-β-cyclodextrin (DMβCD) and the drug substance was obtained. Along with active substances, excipients play a crucial role in the quality, safety, and efficacy of pharmaceutical formulations. Therefore, the compatibility of OLM/DMβCD IC with several pharmaceutical excipients was evaluated. Methods: IC was characterized in both solid and liquid states, employing thermoanalytical techniques, universal-attenuated total reflectance Fourier-transform infrared spectroscopy, powder X-ray diffractometry, UV spectroscopy, and saturation solubility studies. Compatibility studies were carried out using thermal and spectroscopic methods to assess potential physical and chemical interactions. Results: The 1:1 OLM:DMβCD stoichiometry ratio and the value of the apparent stability constant were determined by means of the phase solubility method that revealed an AL-type diagram. The binary system showed different physicochemical characteristics from those of the parent entities, supporting IC formation. The geometry of the IC was thoroughly investigated using molecular modeling. Compatibility studies revealed a lack of interaction between the IC and all studied excipients at ambient conditions and the thermally induced incompatibility of IC with magnesium stearate and α-lactose monohydrate. Conclusions: The results of this study emphasize that OLM/DMβCD IC stands out as a valuable candidate for future research in the development of new pharmaceutical formulations, in which precautions should be considered in choosing magnesium stearate and α-lactose monohydrate as excipients if the manufacture stage requires temperatures above 100 °C.

A New Bis-Urea Based Cage Receptor for Anions: Synthesis, Solid State Structures and Binding Studies.

The synthesis and characterization of a novel bis-urea-based cage receptor for anions (3S,15S)-3,15,20,25-tetramethyl-1,4,6,12,14,17,20,25-octaazatricyclo[15.5.5.17.11]octacosa-7(28),10-diene-2,5,13,16-tetraone (L) is reported. L is a macro-bicyclic ligand built on the 1,7-dimethyl-1,4,7,10-tetraazacyclododecane scaffold to obtain a cage topology in which two ureido moieties have been inserted as binding sites for anions. L can interact with anion guests (G) via H-bonding; in particular, it binds both spherical (Cl-) and V-shaped anions (AcO-) as well as more complex carboxylate anions, such as the norfloxacin (Nor-). NMR experiments highlight that the interaction between L and G mainly occurs at the ureido moieties. L forms L-G adducts of 1 : 1 ([LG]-) and 1 : 2 ([LG2]2-) stoichiometry with Cl- and AcO-. Otherwise, in the case of Nor- only the formation of the [LG]- complex is observed. L shows higher formation constants values for [LAcO]- (2.9) and [LNor]- (3.6) than [LCl]- suggesting a stronger interaction with the carboxylate anions. In the solid state, three crystal structures of the HL⋅G species were obtained (G=Cl-, AcO-, ClO4 -) highlighting the H-bonding interaction between the chloride, acetate or perchlorate anions and the -NH functions of the ureido fragment. The comparison between the two parent open chain receptors (Lb-c) and L has been reported and discussed.

Desing and In Silico Validation of Vitamin B5 and Its Derivatives As A Potential Target Against Cyclophilin A (CyPA)

The title molecule (N-(2,4-dihydroxy-3,3-dimethylbutyryl)b-alanine), DDBBA and its derivatives were selected for theoretical investigations viz geometry optimization, ADME profiling, binding affinity using quantum-mechanical calculations and modelling simulation tools. Geometry optimization by Gaussian 09 program revealed the stability and electrophilic nature of the investigated molecules. In order to depict the charge density distributions that may be related to biological activity, the contour maps of HOMO-LUMO as well as the associated chemical descriptors such as chemical potential (µ), electronegativity (χ), electrophilicity (ω), hardness (η) and softness (σ) were explored. Utilizing molecular docking, the antiviral, antibacterial, and anticancer activities was examined. The docked molecules showed strong propensity for binding to 2HQ6 cancer protein active sites. Vit B5-CH=CF2 and VitB5-CCl3 showed lowest binding energies (-5.861 and -5.478 kcal/mol) and low inhibition constant values (1.43 M). Studies on the (NBO) natural bond orbital, the Mulliken population, and the Fukui function were all analyzed. Further, the interactions between the derivatives and other molecules were studied using Hirshfeld surface analysis.

A systematic approach for synthesizing 3D-printable all-dielectric devices

We present a systematic approach for synthesizing 3D-printable all-dielectric devices. Inverse design approaches yield, in many cases, configurations with a continuous range of dielectric constant values. However, 3D printer resins usually provide a very limited set of such values; commonly, a single resin and air are the only available materials. We propose a methodology for transforming a device with a continuous range of material properties to a manufacturable one, while preserving the device’s performance as close as possible to the continuous case. We develop an algorithm that takes the continuous range of dielectric constant profile as input and generates a binary and connected device that can be 3D-printed using a single resin. Our methodology advances state-of-the-art algorithms by using manufacturable configurations of prescribed local air/resin composition to realize each designed dielectric material instead of being limited to a predetermined shape. The additional degrees of freedom provided by our approach may be particularly useful in devices of conformal complex-shaped dielectric constant profiles. We demonstrate the proposed methodology by designing a 3D-printable wide-angle refraction metagrating with performance very close to the inversely designed device of a continuous dielectric constant profile. The approach can be adapted to accommodate three-dimensional devices and other applications.

Spiral-Hole Moderation Enhances Borehole-Image Interpretation in Carbonates

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper IPTC 23355, “Spiral-Hole Moderation Enhances High-Resolution Borehole-Image Interpretation Across Fractured Carbonate Reservoirs,” by Alawi Altarouti, Abdullah Alotaibi, SPE, and Prudencio Guerreiro, Saudi Aramco, et al. The paper has not been peer reviewed. Copyright 2024 International Petroleum Technology Conference. _ Dynamic phenomena while drilling such as borehole spiraling or corkscrewing can create a physical imprint on the borehole surface, which masks fine features of imaging. During a drilling campaign in a carbonate reservoir using logging-while-drilling (LWD) technology, corkscrewing affected ultrahigh-resolution borehole image quality severely. The complete paper presents the methodology and results of the bit-design test to mitigate the presence of borehole spiraling, resulting in a significantly improved ultrahigh-resolution borehole image. Introduction A recent drilling campaign in an offshore carbonate reservoir in horizontal wellbores required the use of resistivity-based LWD ultrahigh-resolution images (UHRI) with rotary steerable systems (RSS) to evaluate the presence of natural fractures. During LWD logging of the targeted carbonate reservoirs using water-based mud, borehole artifacts were observed as spirals around the borehole. These artifacts had an adverse effect on the borehole-log analysis and interpretation and evaluation of natural fractures, particularly partial fractures that could be masked. In some cases, it was estimated that more than 30% of the fractures could not be identified. Comparing log results of LWD with historical wireline logs run in the same formation and similar well profiles across the field indicated that the artificial spirals only were present when using LWD tools to image the wells. More commonly, borehole spiraling has been observed on a macro scale, wherein the spiraling can be measured in feet. The spiraling in this well was detected only with high-resolution LWD laterolog imaging and affected fracture interpretation. The spiraling remained undetected, below resolution, on the conventional LWD measurements. Methodology Technical Analysis. Spiraling occurred primarily while drilling across relatively soft formations with bulk density values of approximately 2.15 to 2.20 g/cm3. Intervals with higher densities were affected to a lesser extent or not at all. The spiraling occurred in a consistent manner. While downhole shocks and vibration were considered to be a possible cause of spiraling, the periodic occurrence of the traces did not align with the chaotic nature of shocks and vibration. The shape of the traces did not match with possible lateral or axial motions of the bottomhole assemblies (BHAs); however, these spirals may have been caused and aggravated by low-frequency torsional vibrations. Although the level of the stick and slips was found to be medium to high throughout the runs, no evidence supported this theory. The wide range of downhole rotational speed fluctuations could not explain the perfect shape of the spirals. It also was observed that the distance between each trace or spiral correlated with the rate of penetration (ROP) and had constant values in similar ROP ranges. It could have been suspected that the spiraling did not occur across the hard formations because of lower ROP and the overlapping between them as the result of slow drilling. However, the ROP reduced marginally compared with the drilling in the soft formations (approximately only 10%). Thus, ROP was considered one of the lowest-affecting parameters to mitigate spiraling effects.

A fluorescent probe based on scopoletin-3-carboxylic acid: pH and micellization evaluation

Coumarins are a class of compounds known for their synthetic and structural versatility, as well as their properties of great interest, such as biological and photophysical activities, and their application in the analysis of molecular microenvironments and their characteristics, such as pH. In this work, the synthesis of 7-hydroxy-6-methoxy-2-oxo-2H-chromene-3-carboxylic acid (3-SCA) was reported, and its absorption, emission, and excitation spectral properties, along with photophysical properties such as molar absorption coefficient, lifetime, and Stokes Shift (Δν) in different solvents and pHs, were evaluated for the first time. High values of fluorescence quantum yield were observed for 3-SCA in solvents of different polarities, with a lifetime of approximately 5 ns. The Stokes shift values for 3-SCA were high, with these values being greater in aqueous medium. Additionally, the acid equilibrium constant values of 3-SCA were evaluated through absorption, emission, and excitation measurements, resulting in two pKa values of 3.7 for the carboxylic acid group at C-3 and 6.6 for the hydroxyl group at C-7. 3-SCA was successfully applied in determining the critical micellar concentration of the surfactants: anionic (SDS), zwitterionic (SB3-14), neutral (F-127), and cationic (CTAB). The high sensitivity of the spectral properties of 3-SCA as a function of pH, combined with the high Stokes shift values in different media, indicates that 3-SCA is an interesting probe with applications in the evaluation of local pH and micelle formation.

Layer-by-layer growth, apparent instability, and mound coarsening in thin film deposition controlled by thermally activated surface diffusion

Thin film deposition from vapor with adsorbate diffusion and Ehrlich-Schwoebel (ES) barriers at step edges is studied by kinetic Monte Carlo (KMC) simulations and scaling approaches. Mound coarsening with slope selection is shown at the largest thicknesses, where roughness (W) and correlation length (ξ) scale in time with exponents β≈n≈0.25, consistently with theoretical works but contrasting with previous simulations that systematically showed temperature-dependent exponents. At a given film thickness, we show that the mounded morphology is independent of the ES barrier, so that interlayer transport is suppressed, while the temperature increase of W and ξ is consistent with intralayer transport limited by adatom detachment from flat terrace borders. Initial layer-by-layer (LBL) growth occurs above a characteristic temperature that increases with the activation energies of terrace diffusion and of ES barrier, but weakly depends on the external flux. Subsequently, as the surface roughness is near the atom/molecule size, there is rapid roughening where, counterintuitively, larger effective growth exponents (β>0.5, suggesting unstable growth) are correlated with longer LBL regimes. Similar LBL-rough transitions were reported in organic film deposition and the model application to diindenoperylene films suggests a large ES barrier ∼0.4eV. In the mound coarsening regime, W/ξ and θ1/2/Wξ converge to constant values dependent on surface diffusion coefficients (θ is the film thickness). This convergence suggests mound coarsening with slope selection in SnTe films whose effective β is anomalously large, showing how film morphology can be interpreted beyond exponent measurements.

Capillary Electrophoresis-Frontal Analysis (CE-FA) and Molecular Docking Studies on the Albumin-Binding Properties of Dopamine and Serotonin.

Dopamine and serotonin are neurotransmitters that are crucial for numerous physiological processes, including mood regulation, reward, and motor function. Dysregulation of these neurotransmitters is associated with various neuropsychiatric disorders. Albumin in plasma modulates the bioavailability of drugs and free concentrations of bioactive constituents. This study aimed to characterize the interactions of dopamine and serotonin with bovine serum albumin. Capillary electrophoresis in the frontal analysis mode was utilized as an effective method to assess dopamine-bovine serum albumin and serotonin-bovine serum albumin affinity. The free neurotransmitter plateaus were distinctly separated from the bovine serum albumin-neurotransmitter complex plateaus. Free dopamine and serotonin concentrations were determined by monitoring the heights of their respective plateaus. In contrast, the bound concentrations were calculated from the difference between the total and free plateau heights. Dopamine and serotonin were found to bind to bovine serum albumin at independent sites with binding constant values of 1.90×103 and 2.90×103L/mol, respectively. Additionally, an in silico molecular docking approach revealed the binding sites for dopamine and serotonin near the glutamic acid-291 and serine-428 residues of bovine serum albumin, respectively.

Characterization of the Dust and Sodium Tails of Comet C/2020 F3 (NEOWISE) from Parker Solar Probe and Amateur Observations

Comet C/2020 F3 (NEOWISE) reached perihelion on 2020 July 3 at 0.29 au and exhibited a highly structured dust tail. Using a simplified Finson–Probstein model, structures such as striae, observed in the tail in images obtained by the Parker Solar Probe spacecraft and amateur observers, are characterized in this work and parameterized in terms of dust ejection dates and dust β values. Other dust tail features are syndynic bands: bright, curved regions of the dust tail that lie within constant values of dust β. This study is the first in-depth analysis of these structures. Analysis revealed that the dust β distribution in the tail was approximately bimodal, corresponding to the two syndynic bands observed in the tail. The region between these bands, bounded by the β = 0.82 ± 0.02 and β = 1.20 ± 0.02 syndynes, appeared to have a reduced dust population, suggesting that dust grains of these β values were produced at a much lower rate. The alignments of the striae in the tail were measured and compared to the interleaved striae seen in C/2006 P1. C/2020 F3 was found to have no interleaved striae, which is possibly due to the timing of the comet’s heliospheric current sheet crossing, not coinciding with, the main period of dust ejection.

Studies of the Novel Bioactive Acridine‐1,3‐thiazolidin‐4‐one Derivatives With Human Serum Albumin Using Fluorescence Spectroscopy and Molecular Modelling

ABSTRACTIn this study, we employ spectroscopic, thermodynamic and molecular docking approaches to identify the mechanism by which thiazolidinone derivatives 4a–4d bind with human serum albumin. It has been suggested that the affinity of the interaction of derivatives 4a–4d with HSA is within the optimal range necessary for the transportation and distribution of compounds within the organism. The binding constant values for the derivative/HSA complexes were found to be 0.03–5.87 × 105 M−1. Both ΔH0 and ΔS0 values were negative, which indicates that binding occurs mainly through van der Waals forces and hydrogen bonding. The negative values calculated for ΔG0 indicate that the binding of derivatives 4a–4d with HSA is a spontaneous process. Our study also reveals that derivatives 4a–4d bind to the subdomain IB (Site III) of HSA and that this binding alters the conformation and thermodynamic stability of HSA. Molecular docking simulations suggest that the main binding forces are van der Waals interactions, hydrophobic interactions and hydrogen bonds. The studied compounds showed weak DPPH‐scavenging activity at all of the tested concentrations. The results suggest that compound 4b with a phenyl substituent at the nitrogen atom of the 1,3‐thiazolidin‐4‐one moiety can be considered the most potent antioxidant in the series.

Correlation and application of thermal expansion coefficient/elastic modulus for co-sintered composite cermet/ceramic materials

Deformation and stress concentration appearing during high-temperature sintering process significantly affect production quality of solid oxide cell (SOC), due to mismatched mechanical and thermophysical properties of the sintered electrode and electrolyte. In this study, a coarse-grained molecular dynamics (CG-MD) method is developed to evaluate and correlate coefficient of thermal expansion (CTE) and elastic modulus during the entire co-sintering process (including temperature-increasing, −insulation, and -decreasing stages). It is revealed that, in the sintered porous cermet electrode, CTE primarily exhibits an increasing trend until temperature-decreasing stage. Compared to the constant values commonly applied in the literature, the elastic modulus experiences a decay trend with a reduction of 32.14 % in the porous electrode and 9.68 % reduction in the dense electrolyte. The obtained CTE and elastic modulus are correlated with the sintering parameters and further applied to a macroscopical model for predicting overall sintering warpage and stress in a co-sintered SOC half-cell composed of a thick porous electrode and a thin dense layer. The varied CTE is identified as the main factor influencing warpage deformation, while the elastic modulus as a more significant impact on the von Mises stress during the co-sintering of the half-cell. Analysis is further conducted by orthogonal testing method for sintering temperature, sintering time, material content and diameter ratio of the porous cermet nanoparticles, aiming to optimize the varied CTE and elastic modulus, particularly during the temperature-insulation process. Subsequently, the optimized properties are implemented, and it is found that, after sintering insulation for 120 min, the maximum warpage displacement is about 7.34 mm, which represents a decrease of approximately 14.11 %; while the von Mises stress is observed to be 379.24 MPa, which indicates a reduction of around 37.33 % compared with the predictions by the constant properties.

Photocatalytic Degradation of Methylene Blue by Engineering Tungstic Acid@ZIF‐67 Cocatalyst

AbstractThe zeolitic imidazolate frameworks have gained significant attention in various applications owing to their exceptional surface area, customizable porosity, and excellent thermal and chemical stability, making them a remarkable nanomaterial. The present study involved the utilization of ultrasonic‐assisted techniques to integrate tungstic acid into the zeolitic imidazolate framework (TA@ZIF‐67) with the aim of augmenting the photocatalytic activity. The as‐synthesized nanocomposite was characterized using X‐ray diffraction and scanning electron microscopic analysis to inspect the structural aspects and morphology. The reduction in particle size of TA@ZIF‐67 due to the incorporation of tungstic acid results in a higher surface area, leading to a significant improvement in the photocatalytic activity of ZIF‐67. The assessment of the photocatalytic performance of ZIF‐67 and TA@ZIF‐67 was conducted through the degradation of methylene blue (MB) under sunlight. The degradation efficiency of ZIF‐67 and TA@ZIF‐67 was observed to be 61% and 85%, respectively, of the MB solution following a 60 min irradiation period. The investigation of the kinetics study based on rate constant values revealed that the utilization of TA@ZIF‐67 presented a greater efficiency in the removal of MB from an aqueous solution. The results pave a new avenue toward the design of MOF‐based photocatalysts for water treatments.

Designing ZrO2-blended nanocomposite MIM capacitors for future OFET applications and their characterizations

Organic field-effect transistors (OFETs) have been exploited as sensors for a variety of applications due to their excellent advantages over diodes and other electronic devices. Capacitors are one of the key components of the OFET designs that consist of a dielectric layer sandwiched between two parallel metal plates. The dielectric layer should be thin and/or have a high k constant value to achieve a high capacitance value (Ci, areal capacitance), so more charge carriers can be accumulated at the interface between the dielectric and the organic semiconductor, for OFETs to operate under low voltage (< 3 V). In this study, high-k nanocomposites (NCs) of ZrO2 metal oxide ceramic nanoparticles (NPs) in varying concentrations blended in two different polymer matrixes, poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) and cyanoethyl cellulose (CEC) have been utilised as the dielectric layer in metal-insulator-metal (MIM) capacitors. The physical and electrical properties of fabricated MIM capacitors were evaluated. The measured areal capacitance, Ci, values demonstrated a gradual rise with increasing ZrO2 metal oxide content in both polymer matrixes. ZrO2-PVDF-HFP-based capacitors exhibited a two-fold increase in Ci, 91.86 ± 6.1 nF/cm2 (a 140 % increase) for 10 wt % NP content. Similarly, areal capacitance values of 76 ± 3.03 nF/cm2 (a 45 % rise) was measured on MIMs using CZ10 dielectric layer. High average dielectric constant (k) values of 28.61 and 35.68 for CZ5 and PZ5, respectively) were obtained. As expected, leakage current density increased for higher NP % in polymer matrixes. Nevertheless, all MIMs yielded average leakage current density < 1.75 × 10−6 (A/cm2) at 2 V. Therefore, the reported nanocomposites are suitable dielectric layers for OFETs and as platforms for gas, chemical and photoactivated sensing devices.

Fluorescent sensing copolymers: Synthesis, nanofiber fabrication and application in picric acid sensors

Increasing attention has been paid to the detection of explosives due to the occurrence of terrorist attacks around the world. Here, we used free radical polymerization to develop two different types of fluorescent copolymers for use in detecting picric acid. One exhibits aggregation-caused quenching (ACQ) and is called PNNS [poly (N-isopropyl acrylamide-co-N-hydroxymethyl acrylamide -co-styrene-pyrene), poly (NIPAAm-co-NMA-co-St-Py)]. The other possesses aggregation-induced emission (AIE) properties and is called PNNP [poly (N-isopropyl acrylamide-co-N-hydroxymethyl acrylamide-co-2-(1,2,3,4,5-pentaphenyl-1H-silol-1-yloxy) ethyl methacrylate), poly (NIPAAm-co-NMA-co-PPS-HEMA)]. Nanofibrous thin films of these copolymers were obtained by electrospinning. Upon interaction with picric acid, the fluorescence intensity of each copolymer was quenched due to photo-induced electron transfer (PET). The average diameters of PNNS and PNNP nanofibers were 179 ± 28 nm and 235 ± 143 nm, respectively. Sensing performance was evaluated by Stern-Volmer analysis. The Stern-Volmer constant (Ksv) values for PNNS and PNNP nanofibers were 0.012 μΜ−1 and 0.119 μΜ−1, respectively. Since the aggregated state of PNNP nanofibrous thin films can increase dramatically, the AIE property of this material provides a large dynamic range. Finally, the reusability of water- and methanol-washed nanofiber thin films was tested, revealing that the nanofiber sensors were reusable for detecting picric acid.

Effect of grinding methods on slime dissociation characteristics and flotation kinetics of coking coal

Despite extensive research on the connection between coal flotation kinetics and particle size, little is known about the shape effect. To fill this gap, this study aims not only to explore dissociation characteristics and particle shape properties resulting from the grinding of coking coal in a planetary ball mill (PBM) and a vertical shaft impact crusher (VSIC) but also to investigate their effects on flotation kinetics. Moreover, for the first time in the literature, shape, kinetic rate constant, and bubble loading capacity (hydrophobicity) properties of coking coal products ground in two different mills were compared by shape characterization, flotation kinetics, and single bubble loading tests, respectively. The findings are: (1) Compared to PBM, VSIC produced rounder-shaped particles with a better communition selectivity, (2) Since PBM's flotation rate constant values (Km) were higher than VSIC's, the particles produced by the PBM exhibit a favorable aspect ratio for faster flotation.

Estimation of multicomponent reactions’ yields from networks of mechanistic steps

This work describes estimation of yields of complex, multicomponent reactions (MCRs) based on the modeled networks of mechanistic steps spanning both the main reaction pathway as well as immediate and downstream side reactions. Because experimental values of the kinetic rate constants for individual mechanistic transforms are extremely sparse, these constants are approximated here using Mayr’s nucleophilicity and electrophilicity parameters fine-tuned by correction terms grounded in linear free-energy relationships. With this formalism, the model trained on the mechanistic networks of only 20 – but mechanistically- and yield-diverse MCRs – transfers well to newly discovered MCRs that are based on markedly different mechanisms and types of individual mechanistic transforms. These results suggest that mechanistic-level approach to yield estimation may be a useful alternative to models that are derived from full-reaction data and lack information about yield-lowering side reactions.

Elastic waves scattering by the schoty in microscopic system 2D

We investigate the scattering phenomenon at the non-uniform crystalline surface. Localized modes emerge in its vicinity due to the inhomogeneity-induced breakdown of translation symmetry. The phonon scattering mechanisms at the inhomogeneity are investigated by means of the Newton equation and matching approach. Numerical findings are presented across a wide range of scattering energies, together with the estimation of the transmission and reflection probabilities and the elastic wave average transmittance across the defect. This shows how the softening, homogeneity, and hardening characteristics of the perturbed defect vary in their scattering spectra. Fano resonances in the spectra are caused by the coherent coupling between the localized modes created by the defect and the propagating mode of the ideal waveguide. For a variety of values of the elastic constants in the bulk and inhomogeneous domain, a comprehensive explanation is given. The features of the system model and the stimulating dimensionless frequencies are used to calculate the conductance of the system.