Absorption Parameters Research Articles

Mathematical Study of unsteady micropolar fluid flow due to non-linear stretched sheet in the presence of magnetic field

The goal of this research is to check irregularity in heat generation, chemical reaction and thermal radiation effect an unsteady micropolar fluid flow. With the help of suitable similarity variables, the group of governing system of PDE and their associative boundary conditions are converted into the family of ODE and then solved using the HAM. The effect of various and important dimensionless parameters on the momentum, micro-rotation, energy and concentration equations have been discussed with graphical representation as well as tabular forms. It is observed that buoyancy force parameter, mixed convection parameter and permeability parameter enhance the velocity distribution while micropolar reduces the velocity profile. The temperature profiles are boosted for time and space dependent heat generation and absorption parameter respectively but reverse trend is observed for Prandtl number and unsteadiness parameter. Skin-friction factor, mass transfer rate and heat transfer rate have been listed and displayed in tables.

The Effect of Soil Depth on the Radiation Absorption Parameters of Soil Samples

The Effect of Soil Depth on the Radiation Absorption Parameters of Soil Samples

Peristaltic mechanism of couple stress nanomaterial in a tapered channel

This paper addresses the analysis of chemical reaction for mixed convection peristaltic movement of electrically conducting couple stress nanomaterial in an asymmetric tapered porous channel under the influence of heat generation/absorption. The heat and mass performances of nanofluid are captured with an evaluation of the famous Buongiorno model, which enables us to determine the attractive features of Brownian motion and thermophoretic diffusion. The velocity slip and viscous dissipation effects are also be accounted. Mathematical modeling incorporates lubrication approximation. The expressions for temperature, pressure rise, concentration, velocity, pressure gradient, and streamlines are estimated numerically and scrutinized for dissimilar flow parameters such as magnetic parameter 1≤M≤4, Darcy number 0.1≤Da≤0.5, couple stress fluid parameter 3≤γ≤6, Brinkman number 1≤Br≤4, heat absorption parameter 1≤B≤2, Brownian motion parameter 1≤Nb≤4, thermophoresis parameter 1≤Nt≤4, Schmidt number 0.3≤Sc≤1.5 and chemical reaction parameter 0.4≤kc≤0.9. Furthermore, the skin friction and Nusselt number at the channel walls are established for a choice of assessments of significant parameters and which are exhibited in a tabular manner. Outcomes reveal that velocity and pressure gradient increase by enhancing the velocity slip parameter. Further, the thermophoresis parameter favors the nanofluid temperature and declines the concentration. To ensure the accuracy of the developed code, obtained results are compared with the results available in the literature and found in excellent agreement.

Nitrogen Sources in Young Peach Trees in the Presence and Absence of Paspalum notatum Co-Cultivation

Nitrogen (N) sources are applied to soils cultivated with peach trees. But, soil cover crops, as Paspalum notatum, a Pampa biome native species, commonly present in orchards, can absorb part of N, decreasing the amount used by peach trees. The study aimed to evaluate N absorption and physiological parameters of young peach trees cultivated in soil with the presence and absence of Paspalum notatum. The experiment was carried out for 180 days in a greenhouse, where N sources were applied to peach trees in the presence or absence of Paspalum notatum. Urea and organic compost were used. Dry matter, tissue N and physiological parameters were evaluated in peach trees. Dry matter and tissue N were evaluated in Paspalum notatum. Nitrogen in soil was evaluated. The N uptake by the peach trees with urea application, on average, was 32% higher than the N uptake by the peach trees in the control treatment or with organic compost, regardless of the presence or absence of Paspalum notatum. Cultivation with Paspalum notatum decreased N uptake by peach trees and, consequently, peach trees photosynthetic pigment content, and stimulated senescence anticipation in about 30 days. However, the total dry matter of peach trees cultivated with Paspalum notatum in any of the treatments applied was not modified. These results may guide new ways of co-cultivating cover crops and young peach trees.

Correlation assessment between degradation ratios of UCS and non-destructive properties of rock under freezing-thawing cycles

Bedrocks of engineering projects are commonly affected by freezing-thawing (F-T) process in mountainous areas. Consequently, determining the degradation rate of rocks due to F-T cycles in cold areas has a key role in project design and its safety level. In this research, influence of F-T process on some physico-mechanical characteristics of three main rocks of Angouran mine (limestone, amphibolite-schist, and mica-schist) was investigated. For this purpose, unconfined compressive strength (UCS), Schmidt hardness, dry density, water absorption and porosity were firstly determined at five different F-T cycle numbers between 0 and 75 cycles. Increasing of the F-T number led to decrease of UCS, Schmidt hardness and dry density, whereas water absorption and porosity parameters were increased. It is also proved that the UCS loss of rock samples due to the F-T process was related to the losses of other physic-mechanical properties. Therefore, the changes of UCS losses were determined at 0, 7, 15, 40, and 75F-T cycles to establish their relationships. According to the results, after 75 cycles, there is a good relationship between UCS degradation ratio with those of the water absorption and Schmidt hardness (R2 = 0.99).

Influence of multi-walled carbon nanotubes in polytetrafluoroethylene on the parameters of electronic structure and absorption of ultra-high-frequency radiation

Using the methods of angular correlation of annihilation radiation (ACAR), attenuation of electromagnetic radiation in 1.5–2.2 GHz frequency range, and optical ellipsometry, it was shown that in composites of polytetrafluoroethylene (PTFE) + multi-walled carbon nanotubes (MWCNTs), a 2% decrease in the probability of annihilation of positrons in free volumes in PTFE leads to changes in other parameters of electronic structure of composites by 8–29%. Polytetrafluoroethylene is transparent to electromagnetic radiation, but after the addition of 10 wt.% or more of MWCNTs, the composites demonstrate 200–410-fold decrease in the electromagnetic radiation intensity when the radiation passes through a specimen with a thickness of ≈2 mm. It was found that the average radius of the free volumes and the probability of annihilation of positrons are determined by the defect and electronic structures of the polymer matrix only. The Fermi angle and the probability of positrons annihilation with free electrons are determined by the analogous structures of MWCNTs only. Since the electronic characteristics of the atoms and defects in the polymer matrix (at least outside the interphase) do not change, the changes in the other ACAR parameters are mainly due to changes in the imperfect MWCNTs’ atomic and electronic structures. The average radius of free volumes reaches its maximum value in the composite with 10 wt.% MWCNTs. It was found that in a specimen with 10 wt.% MWCNTs, the highest density of free electrons is observed due to charge transfer from free volumes to MWCNTs, and the highest electron density is observed on defects. A disorder of MWCNTs and their branched conductive network can form the ‘tails’ of electronic density of states in a band gap. Thus, composite with 10 wt.% MWCNTs has the highest absorption coefficient for electromagnetic radiation.

Unsteady MHD natural convection flow past an infinite vertical porous plate with radiation absorption effects

AbstractIn this paper, we have explored the unsteady hydromagnetic free convective flow over an infinite perpendicular porous plate with temperature resource and/or radiation absorption. The prevailing equations are subsequently resolved systematically by utilizing perturbation methodology. The velocity, temperatures as well as concentrations sketches are shown in graphics. The impacts in the flow area for dissimilar leading parameters have been explored. Also, the skin friction, Nusselt quantity along with Sherwood quantity are computed with different parameters and mentioned in the tables. The velocity diminishes with escalating in the chemically reacting parameter as well as improves with an increment in temperature resource parameters. The temperature field reduces with an augment in the Prandtl number, whereas it enlarges with an augment in temperature absorption parameters. The concentrations field is enhanced by an amplifying in chemically reacting variable, whereas it lessens with an amplifying Schmidt number.

Spectral Light Absorption Coefficient of Particles and Colored Dissolved Organic Matter in the Sea of Azov

The research was carried out based on the results of measuring the concentration of chlorophyll-a (TChl-a), spectral coefficient of light absorption by phytoplankton, non-algal particles (NAP) and colored dissolved organic matter (CDOM) in the southern part of the Sea of Azov in different seasons from 2016 to 2020. New data for the Sea of Azov on the variability of the spectral coefficient of light absorption by all optically active components have been obtained. A high (more than an order of magnitude) variability of all studied parameters was shown. The seasonal dynamics of TChl-a shows maxima in winter and summer. A relationship between the phytoplankton absorption and TChl-a has been revealed, which is described by a power function. Significant seasonal differences (two or more times) between the coefficients in the equation for parametrization of light absorption by phytoplankton were revealed. The NAP and CDOM light absorption were parametrized, the ranges of variability of the absorption coefficient and the exponential slope were revealed, and their seasonal dynamics was shown. Annual variability of absorption coefficient of NAP and CDOM was opposite to the annual cycle of TChl-a. The NAP and CDOM absorption coefficients increased after phytoplankton blooms, when TChl-a decreased. The relative contribution of phytoplankton, NAP, and CDOM to the total absorption by particles and dissolved matter at 440 nm varied significantly over the year. The share of phytoplankton was maximum in winter and summer, while in spring and autumn the maximum contribution to absorption was made by CDOM and NAP.

Intensification of hydrogen sulfide absorption by diethanolamine in industrial scale via combined simulation and data-based optimization strategies

A novel combinatorial approach including computer-aided simulation and robust statistical data-based methods was introduced to intensify the chemical absorption process of H2S by diethanolamine (DEA) from sour industrial off-gas. Effects of three parameters (lean amine H2S impurity (LAHI), lean amine temperature (LAT) and column pressure (CP) on the alteration trends and sensitivity of H2S removal were studied using response surface methodology (RSM) and Sobol’s sensitivity analysis (SA). Then, the optimal conditions for maximizing the H2S removal were determined. Results depicted that H2S removal will be decreased at higher LAHI and LAT. SA showed that LAHI (83%) was the most impactful factor on H2S removal. LAT (15%) and CP (2%) showed a relatively-low and negligible effects on the removal efficiency, respectively. It was shown that low impact of LAT and CP on H2S removal arised from weak variations of thermodynamic parameters of H2S absorption (H2S solubility, equilibrium constant, and enthalpy of absorption) with those factors. Maximum H2S removal of 99.995% was resulted at the optimal values of LAHI = 0.01 molH2S/molDEA, LAT = 53.7 °C, and CP = 1500 kPa.

Optical characterization and theoretical investigations of (Ge2S8)100-xTex chalcogenide system for the IR applications

The present research reports the optical and theoretical studies for (Ge2S8)100-xTex (0 ≤ x ≤ 12) amorphous chalcogenide thin films. The glassy samples have been prepared from the traditional melt quenching technique. The thermal evaporation process has been involved in depositing the thin films on clean glass substrates under a vacuum of 10−5 mbar and at room temperature. The X-ray diffraction patterns affirm the amorphous nature of the samples under investigation. The absorbance spectra have been utilized to estimate the absorption parameters, optical band gap (Eg) and tailing parameter of the Ge-S-Te system. The value of Eg and the energy of the absorption edge decrease; however, band tail-width energy values increase when the Te ratio is enhanced in the binary Ge–S system. The physical parameters viz. density (ρth), compactness (δ), and molar volume (Vm) have also been evaluated for the current system. Conduction band and valence band positions have also been estimated, and a correlation between the refractive index (n) and Eg has been set up. Results indicate that Ge-S-Te system samples are appropriate for various optical applications.

Temperature dependence of the complex permittivity in microwave range of some industrial polymers

The microwave properties of a number of polymers common in industry are investigated. A cylindrical resonator in the TM012 mode is used. The cavity perturbation method and detailed COMSOL simulations are applied for extracting the complex permittivity as a function of temperature. The results are useful for the design of plastic processing tools by heating with electromagnetic fields. The intrinsic parameters of absorption are derived based on two exponential decays: polarization and Arrhenius dependence of the decay times on temperature.

Development and Simulation of Natural Gas Refining Mechanism Based on Exergy Study

Abstract: This study will examine a domestic gas field in Bayelsa, Nigeria, to improve the natural gas purification process. This study's main goals are to reduce energy use and improve purification levels. A complete technical and economic assessment was carried out utilizing Aspen Plus TM software. The absorption parameters reflux ratio and stage number were estimated using single-factor sensitivity analysis. The energy system's energy-saving technique was used to examine the heat transfer mechanism and recommend a change. The optimization results show that the suggested system has better purifying performance, lower total energy consumption, and 9 percent improved energy efficiency.

Spectral relaxation computation of Maxwell fluid flow from a stretching surface with quadratic convection and non-Fourier heat flux using Lie symmetry transformations

A mathematical model for nonlinear quadratic convection with non-Fourier heat flux in coating boundary layer flow of a Maxwell viscoelastic fluid is presented. Nonlinear quadratic thermal radiation and heat source/ sink effects are also considered. The transformations of Lie symmetry are employed. The resultant nonlinear differential equations with defined boundary conditions are numerically solved using the spectral relaxation technique (SRM), a robust computational methodology. Graphical visualization of the velocity and temperature profiles is included for a range of different emerging parameters. For skin friction and the Nusselt number, numerical data are also provided. There is a very strong correlation between the outcomes of this study and those published in the literature. Higher values of the nonlinear thermal radiation, mixed convection, thermal conductivity, nonlinear convection and heat source/ generation parameters increase temperature as well as the thickness of the thermal boundary layer. However, a higher Prandtl number, thermal relaxation parameter and heat sink/ absorption parameter all reduce temperature. Deborah number causes velocity to be raised (and momentum boundary layer thickness to be lowered), whereas raising nonlinear mixed convection parameter causes velocity to be decreased (and momentum boundary layer thickness to be increased), and a velocity overshoot is calculated. The models are applicable to simulations of high-temperature polymeric coatings in material processing.

Green monoterpenes based deep eutectic solvents for effective BTEX absorption from biogas

The combustion of biogas which contains significant amounts of monoaromatic hydrocarbons, i.e. benzene, ethylbenzene, toluene, and xylene (BTEX) can cause many technological, environmental, and health problems. Therefore, in these studies, a new physical absorption method based on deep eutectic solvents (DES) consisting of monoterpenes and carboxylic acids was developed for BTEX removal. A total of 39 DES were synthesized, of which seven were selected based on their affinity to BTEX, favorable physicochemical properties, and “green” character. Detailed structural (i.e. 1H NMR, 13C NMR, and FT-IR) and physicochemical experiments (i.e. melting point, density, viscosity, and surface tension) were performed for the DES. Then, DESs were used for the absorption process in both the laboratory and enlarged scale. BTEX absorption was monitored using two methods, including "in-situ" gas chromatography, and "online" sensors matrices. The crucial absorption parameters i.e. type of DES, temperature, and regeneration possibility were carefully studied. The mechanism of BTEX absorption was explained using experimental spectroscopic techniques and theoretical analysis based on the COSMO-RS model. The obtained results indicate that Eucalyptol:Octanoic acid can selectively capture BTEX from a biogas mixture due to the formation of electrostatic interaction. DES absorption capacity is 53.96 mg/g, which is comparable with commercially available absorbents.

Machine learning and artificial intelligence in physiologically based pharmacokinetic modeling.

Physiologically based pharmacokinetic (PBPK) models are useful tools in drug development and risk assessment of environmental chemicals. PBPK model development requires the collection of species-specific physiological, and chemical-specific absorption, distribution, metabolism, and excretion (ADME) parameters, which can be a time-consuming and expensive process. This raises a need to create computational models capable of predicting input parameter values for PBPK models, especially for new compounds. In this review, we summarize an emerging paradigm for integrating PBPK modeling with machine learning (ML) or artificial intelligence (AI)-based computational methods. This paradigm includes 3 steps (1) obtain time-concentration PK data and/or ADME parameters from publicly available databases, (2) develop ML/AI-based approaches to predict ADME parameters, and (3) incorporate the ML/AI models into PBPK models to predict PK summary statistics (eg, area under the curve and maximum plasma concentration). We also discuss a neural network architecture "neural ordinary differential equation (Neural-ODE)" that is capable of providing better predictive capabilities than other ML methods when used to directly predict time-series PK profiles. In order to support applications of ML/AI methods for PBPK model development, several challenges should be addressed (1) as more data become available, it is important to expand the training set by including the structural diversity of compounds to improve the prediction accuracy of ML/AI models; (2) due to the black box nature of many ML models, lack of sufficient interpretability is a limitation; (3) Neural-ODE has great potential to be used to generate time-series PK profiles for new compounds with limited ADME information, but its application remains to be explored. Despite existing challenges, ML/AI approaches will continue to facilitate the efficient development of robust PBPK models for a large number of chemicals.

An unsteady MHD flow of a second‐grade fluid passing through a porous medium in the presence of radiation absorption exhibits Hall and ion slip effects

AbstractIn the presence of radiation absorption, we analyzed the effects of Hall and ion slip effects on an unsteady laminar magnetohydrodynamics convective rotating flow of heat‐producing or absorbing second‐grade fluid across an inclined moving permeable surface in the presence of chemical reaction and radiation absorption. Using the perturbation method, the nondimensional equations for the governing flow are solved to the most excellent conceivable investigative answer. The effects of various factors on velocity, temperature, and concentration are visually and explored in depth. Shear stresses, Nusselt number, and Sherwood number are calculated analytically, rendered computationally in a tabular style, and discussed concerning the essential characteristics for engineering inquiry. It is inferred that an increase in radiation absorption, Hall, and ion slip parameters across the fluid area leads to a rise in the resulting velocity. The thermal and solutal buoyancy forces contribute to the resultant velocity, constantly growing to a very high level. The rotation parameter is used to reduce skin friction, while the Hall and ion slip effects enhance it. The rate of mass transfer increases when the chemical reaction parameter is raised.

Solute transport in laminar channel flows with floating vegetation islands: Dispersion and vegetation absorption

In view of the concerns regarding contaminant transport and removal after water pollution incidents, this study focuses on the temporal and spatial evolutions of concentration distribution and removal performance in channel flows with floating vegetation islands (FVIs). For a typical case of instantaneous and uniform contaminant release, the analytical solution of the spatial concentration distribution is deduced based on the multi-scale perturbation method. With the combined effects of advection and vegetation absorption, a tremendous concentration gradient forms on cross-sections and cannot be smeared out until the contaminant is completely removed. Both the vertical and longitudinal concentration distributions are reshaped in different degrees due to the different intensities of vegetation absorption. The stronger the vegetation absorption is, the greater the vertical distribution of the mass proportion deviates from that for pure dispersion. By establishing the relationships of the removal rate and removal efficiency with the residence time, distance and absorption parameter based on the control volume analysis, the temporal and spatial evolutions of the removal performances with different absorption intensities are assessed quantitatively. The significantly reduced critical lengths and durations of influenced regions confirm the ecological effects of FVIs from the perspective of hydraulic research.

Recent Development of Heat and Mass Transport in the Presence of Hall, Ion Slip and Thermo Diffusion in Radiative Second Grade Material: Application of Micromachines.

This article describes the incompressible two-dimensional heat and mass transfer of an electrically conducting second-grade fluid flow in a porous medium with Hall and ion slip effects, diffusion thermal effects, and radiation absorption effects. It is assumed that the fluid is a gray, absorbing–emitting but non-scattering medium and the Rosseland approximation is used to describe the radiative heat flux in the energy equation. It is assumed that the liquid is opaque and absorbs and emits radiation in a manner that does not result in scattering. It is considered an unsteady laminar MHD convective rotating flow of heat-producing or absorbing second-grade fluid across a semi-infinite vertical moving permeable surface. The profiles of velocity components, temperature distribution, and concentration are studied to apply the regular perturbation technique. These profiles are shown as graphs for various fluid and geometric parameters such as Hall and ion slip parameters, radiation absorption, diffusion thermo, Prandtl number, Schmidt number, and chemical reaction rate. On the other hand, the skin friction coefficient and the Nusselt number are determined by numerical evaluation and provided in tables. These tables are then analysed and debated for various values of the flow parameters that regulate it. It may be deduced that an increase in the parameters of radiation absorption, Hall, and ion slip over the fluid region increases the velocity produced. The resulting momentum continually grows to a very high level, with contributions from the thermal and solutal buoyancy forces. The temperature distribution may be more concentrated by raising both the heat source parameter and the quantity of radiation. When one of the parameters for the chemical reaction is increased, the whole fluid area will experience a fall in concentration. Skin friction may be decreased by manipulating the rotation parameter, but the Hall effect and ion slip effect can worsen it. When the parameter for the chemical reaction increases, there is a concomitant rise in the mass transfer rate.

Regulation of glomerulotubular balance. IV. Implication of aquaporin 1 in flow-dependent proximal tubule transport and cell volume.

The water channel aquaporin-1 (AQP1) is the principal water pathway for isotonic water reabsorption in the kidney proximal tubule (PT). We investigated flow-mediated fluid (Jv) and [Formula: see text] ([Formula: see text]) reabsorption in PTs of the mouse kidney by microperfusion in wild-type (WT) and AQP1 knockout (KO) mice. Experiments were simulated in an adaptation of a mathematical model of the rat PT. An increase in perfusion rate from 5 to 20 nL/min increased Jv and [Formula: see text] in PTs of WT mice. AQP1 KO mice significantly decreased Jv at low and high flow rates compared with control. In contrast, [Formula: see text] was not reduced at either low or high flow rates. Cell volume showed no significant difference between WT and AQP1 KO mice. Renal clearance experiments showed significantly higher urine flow in AQP1 KO mice, but there was no significant difference in either Na+ and K+ or [Formula: see text] excretion. Acid-base parameters of blood pH, Pco2, [Formula: see text], and urine pH were the same in both WT and KO mice. In model calculations, tubules whose tight junction (TJ) water permeability (Pf) was that assigned to the rat TJ, showed no difference in Jv between WT and KO, whereas TJ Pf set to 25% of the rat predicted Jv concordant with our observations from AQP1 KO. These results affirm the dominance of AQP1 in mediating isotonic water reabsorption by the mouse PT and demonstrate that flow-stimulated [Formula: see text] reabsorption is intact and independent of AQP1. With reference to the model, the findings also suggest that TJ water flux in the PT is less prominent in the mouse than in the rat kidney.NEW & NOTEWORTHY We found an absence of flow-dependent modulation of fluid absorption but no effect on either proximal tubule (PT) [Formula: see text] absorption or acid-base parameters in the aquaporin 1 (AQP1) knockout mouse. We affirmed the dominance of the water channel AQP1 in mediating isotonic water reabsorption by the mouse PT and demonstrated that flow-stimulated [Formula: see text] reabsorption is independent of AQP1. With reference to the model, the findings also suggest that tight junctional water flux in the PT is less prominent in the mouse than rat kidney.

Effect of calcination temperature on structural, antibacterial, radiation shielding and magnetic properties of cubic spinel cobalt nanoferrite

For the first time, Cobalt ferrite (CoFO) nanoparticles (NPs) were synthesized by solution combustion method using BigThyme leaf extract as a reducing agent followed by varying the calcination temperature as-formed — 800 °C. At all the calcination temperatures, Bragg reflections matches well with FCC cubic spinel structure. Crystallite size increases from 12–79 nm with increase in calcination temperature. The SAED pattern and d-spacing from Transmission electron microscopy matches well with the PXRD pattern and the calculated crystallite size matches well with the Scherrer’s formula. The direct energy band gap was found to be 1.55 eV. The effect of calcination temperature on different magnetic properties such as retentivity, coercivity, saturation of magnetization, squareness ratio and Bohr magneton was discussed in detail. Large coercivity (2.26 kOe) is observed at low calcination temperature. Further, X-ray/gamma radiation absorption parameters such as mass attenuation coefficient, half value layer and Zeff are established which is an essential in the field of radiation dosimetry. CoFO NPs exhibited sensitivity against both Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria. The cytotoxic properties were examined on cervical cancer HeLa cells and compared with the cisplatin drug. CoFO NPs shows higher % cell viability and less % cell death. Thus, CoFO NPs can be used as a drug carrier in cancer therapy.