Values Of Effective Diffusion Coefficient Research Articles

Migration of copper(II) ions in humic systems—effect of incorporated calcium(II), magnesium(II), and iron(III) ions

The mobility of heavy metals in natural soil systems can be affected by the properties and compositions of those systems: the content and quality of organic matter as well as the character of inorganic constituents. In this work, the diffusion of copper(II) ions in humic hydrogels with incorporated calcium(II), magnesium(II), and iron(III) ions was investigated. The methods of instantaneous planar source and of constant source were used. Experimental data yielded the time development of the concentration in hydrogels and the values of effective diffusion coefficients. The coefficients include both the influence of the hydrogel structure and the interaction of diffusing particles with the hydrogel. Our results showed that the presence of natural metal ions such as calcium, magnesium, or iron can strongly affect the diffusivity of copper in humic systems. They indicate that the mobility of copper ions depends on their concentration. The mobility can be supported by higher contents of copper in the system. While the incorporation of Ca and Mg resulted in the decrease in the diffusivity of copper ions, the incorporation of Fe(III) into humic hydrogel resulted in an increase in the diffusivity of Cu(II) in the hydrogel in comparison with pure humic hydrogel.

Laboratory investigation on the retention performance of a soil-bentonite mixture used as an engineered barrier: insight into the effects of ionic strength and associated heavy metal ions.

Soil-bentonite (S-B) materials are promising backfill materials for use as engineered barriers in heavy metal-contaminated sites. The effects of contaminant exposure on the retention performance of the S-B barrier remain unrevealed. In this study, based on the pollution status of an abandoned ferroalloy factory located in southern China, the retention performance of the S-B mixture toward Cr(VI) and Zn(II) was studied through adsorption and diffusion experiments sequentially; the separate effect of ionic strength (binary solution) and the combined effect of ionic strength and associated heavy metal ion (ternary solution) were discussed. In NaCl-Cr(VI)/Zn(II) binary solutions, the adsorption of Zn(II) onto the S-B mixture is larger than that of Cr(VI). Kd, Qmax, and ɛacc (accessible porosity) of Cr(VI) increase through increasing ionic strength, while Zn(II) shows the opposite trend; De (effective diffusion coefficient) values for both Cr(VI) and Zn(II) increased with increasing ionic strength and follow a sequence of Cr(VI) > Zn(II), indicating a better retention performance of the S-B mixture to Zn(II). For a given ionic strength, the adsorption of Zn(II) was larger than that of Cr(VI), which can be attributed to the retention specificity of the S-B mixture to anion and cation. In Cr(VI)-Zn(II)-NaCl ternary solutions, the adsorptions of Cr(VI) and Zn(II) are enhanced in varying degrees when compared with their binary solution, which probably could be attributed to the ion bridge role of Cr(VI)/Zn(II) to connect each other that relatively increased the adsorption capacity of S-B material. This work will contribute to an in-depth understanding of the retention performance of the S-B mixture in complicated chemical environments and facilitate the selection of future remediation strategies.

How the Addition of Chitosan Affects the Transport and Rheological Properties of Agarose Hydrogels

Agarose hydrogels enriched by chitosan were studied from a point of view diffusion and the immobilization of metal ions. Copper was used as a model metal with a high affinity to chitosan. The influence of interactions between copper and chitosan on transport properties was investigated. Effective diffusion coefficients were determined and compared with values obtained from pure agarose hydrogel. Their values increased with the amount of chitosan added to agarose hydrogel and the lowest addition caused the decrease in diffusivity in comparison with hydrogel without chitosan. Liesegang patterns were observed in the hydrogels with higher contents of chitosan. The patterns were more distinct if the chitosan content increased. The formation of Liesegang patterns caused a local decrease in the concentration of copper ions and concentration profiles were affected by this phenomenon. Thus, the values of effective diffusion coefficient covered the influences of pore structure of hydrogels and the interactions between chitosan and metal ions, including precipitation on observed Liesegang rings. From the point of view of rheology, the addition of chitosan resulted in changes in storage and loss moduli, which can show on a "more liquid" character of enriched hydrogels. It can contribute to the increase in the effective diffusion coefficients for hydrogels with higher content of chitosan.

Investigation on Purification of Saturated LiNO3 Solution Using Titanium Phosphate Ion Exchanger: Kinetics Study

Lithium compounds are of high interest to many industries. The presence of undesirable impurities in Li precursors leads to uncontrolled change in the functional properties of final compounds. Therefore, the development of reliable methods for lithium salt purification is considered a key factor for their application in various industries. This work focuses on the application of a titanium phosphate ion exchanger (Li-TiOP) toward Cu2+, Co2+, Mn2+, Ni2+, and Cr3+ ions in the purification of a saturated LiNO3 solution. The sorption kinetics of the selected ions, considering external and internal mass transfer, as well as chemical interaction, were deeply studied. The kinetic study showed that the values of intraparticle diffusion rate and effective diffusion coefficients for the studied ions decreased in the following order: Cr(III) ˃ Cu(II) Mn(II) ˃ Co(II) ˃ Ni(II). For all the selected ions, chemical interaction was described with a pseudo-second-order reaction model. The sorption kinetics were controlled by the size of the solvated metal ion, its effective charge, the electronic structure of the adsorbed ion, and the interaction with the functional groups of the sorbent. Due to fast kinetics, the high degree of removal of trace quantities of the impurities this material gives it consideration as a promising sorbent for the deep purification of lithium salts.

Mikrodalga Destekli Köpük Kurutma Yöntemi ile Kurutulan Ejder Meyvesi Tozlarının Kuruma Kinetiği ve Toz Ürün Özelliklerinin İncelenmesi

In this study, dragon fruit was dried by a microwave-assisted foam drying method and the effect of different microwave powers (350, 460 and 700W) on the drying kinetics and powder product properties were investigated. The properties (foam stability, expansion and density) of the foams obtained by adding egg white to dragon fruit puree were examined. The highest R2 and lowest RMSE and χ2 values of foam dried samples obtained from the Silva models. The effective moisture diffusion coefficient values of the samples (5.93×10-8-1.16×10-7 m2/s) increased due to the increase of microwave power. Activation energy values were calculated as 74.77 W/g. The effects of different microwave powers on moisture, water activity, color and powder product properties of dragon fruit powders dried by foam drying method were determined. In addition, in all conditions where microwave foam drying is performed, dragon fruit powders showed very good flowability and low stickiness.

Evaluation of In Vitro Skin Permeation of Enzymatically Synthesized Phloridzin Acetates from Emulsions and Liposomes Dispersed in Gel

AbstractThis work aims to evaluate the effect of cosmetic formulations on the skin permeation of phloridzin acetates, therefore in vitro transdermal delivery of these bioactive compounds across Strat‐M membrane is investigated. The formulations tested are gel emulsion, oil in water emulsion (O/W emulsion), gel in oil emulsion, liquid crystal emulsion, and liposomes dispersed in gel. The release of esters from the O/W emulsion is diffusion‐controlled (n = 0.5), while release kinetics from gel‐based formulations depends on coupled diffusion and polymer relaxations effect (0.5 < n < 1). The highest values of effective diffusion coefficient are obtained after release from O/W emulsion (24.64 × 10−10 m2 min−1 for phloridzin acetate and 6.55 × 10−10 m2 min−1 for phloridzin diacetate). The lag phase lasting from 1 h (gel emulsion) to 5 h (liquid crystal emulsion) indicates that esters permeation is significantly affected by the formulation used. Formulations in which the water is continuous phase are the most appropriate carrier system for transdermal delivery of phloridzin esters. Additionally, liposomes are successfully applied as carrier systems for the controlled release of esters, although it should be noted that liposomes without cholesterol show remarkable stability (ζ = −43 mV) and homogeneity (polydispersity index = 0.198).Practical application: Phloridzin is a flavonoid glycoside that possesses many beneficial activities such as antioxidant, UV‐protecting, and anti‐inflammatory activity, so the use of this flavonoid and its derivatives in numerous cosmetic and pharmaceutical formulations seems very attractive. Results obtained in this study give a comprehensive insight into the release mechanism of phloridzin acetates from emulsions and liposomes, enable the selection of optimum cosmetic formulations depending on the application, and provide significant scientific contribution in the field of topical administration of bioactive flavonoid derivatives.

Application of Mathematical Models and Thermodynamic Properties in the Drying of Jambu Leaves

Jambu is a vegetable originally from the northern region of Brazil, has bioactive properties, being little explored by other regions, due to its high peresivity. And one of the methods to increase the shelf life of plant products is the removal of water. The objective of this work was to evaluate the drying kinetics of jambu leaf mass. Two treatments were carried out: The mass of fresh jambu leaves and the mass of fresh jambu leaves with the addition of drying foam, both submitted in an oven with forced air circulation at temperatures (50, 60 and 70 °C and thickness of 1.0 cm). The proximate composition of the materials was performed before and after drying. Twelve mathematical models were tested on drying kinetics data and thermodynamic properties were calculated. The parameters of the proximate composition for the mass of leaves and foam after drying were: Moisture content of (2 to 7%), ash content of (13 to 17%), protein content of (22 to 30%), lipids of (0.6 to 4%) and total titratable acidity (0.20 to 0.28%) of tartaric acid. The models that best fit the experimental data to describe the drying kinetics of jambu masses were: Wang & Singh. The use of foam mat presented higher values of effective diffusion coefficient and activation energy and lower values of enthalpy and entropy, reducing the drying time.

Extraction of phenolic compounds from apple pomace, process modeling and antioxidant potential evaluation of extracts

Abstract Apple pomace, a byproduct of juice and cider production, is rich in phenolic compounds with antioxidant activity. This work studies the kinetics of solid–liquid extraction of phenolic compounds from apple pomace. Extraction kinetics were determined using a 50% water–ethanol solution and fitted to a phenomenological model. Equilibrium isotherms were also modeled. Effective diffusion coefficient values between 1.85x10−11 and 7.37x10−11 m2/s were found. External mass transfer resistance showed negligible results. The best yields (43.94%) were obtained at 60 °C with a solid–liquid ratio of 1:10 g/mL. Those conditions resulted in a total phenolic content of 9.95 mg gallic acid equivalents (GAE)/g apple pomace d.b., antioxidant FRAP activity of 5.07 mmol ascorbic acid equivalents (AAE)/100 g apple pomace d.b. and 3.74 mmol trolox equivalents (TRE)/100 g apple pomace d.b. based on a DPPH assay. Apple pomace extract efficiently stabilized sunflower oil and may represent a natural alternative to synthetic antioxidants.

EFFECT OF ULTRASOUND PRE-TREATMENT ON DRYING KINETICS AND QUALITY PROPERTIES OF JERUSALEM ARTICHOKE

-- Jerusalem artichoke (Helianthus tuberosus L.) is primarily used as a biomass for ethanol production. It is also utilized for human consumption as a healthy snack by having good nutritional value and inulin content. In this study, ultrasound pre-treatment (USPT) was selected to minimize drying defects and 5, 10 and 15 min. treatments were applied before hot air drying at 60 °C and 80 °C. The effect of pre-treatment on drying performances and properties as color, total phenolic content and total antioxidant were investigated. Effective diffusion coefficient values ​​ranged from 1.72 × 10-8 m2/min to 2.94 × 10-8 to m2/min, and it was observed that the effective moisture diffusion coefficient was higher in the samples where ultrasound was applied compared to the control sample. L * value 72.72 ± 2.71 was found highest at samples that were 5 minutes ultrasound treated and dried at 60 ° C for 60 minutes. The highest antioxidant and phenolic content in the drying process at 60 °C was determined in the samples where ultrasound was applied for 15 minutes. Consequently, more conserved quality in shorter drying time with desired end product moisture content can be achieved by the application of USPT.

Evaluation of heat mass performances for freeze drying of mint leaves

Mint leaves are one of the most used medicinal and aromatic plants in the world, having a wide range of minerals and vitamins. It is necessary to prevent nutrient content and quality loss during the drying of the leaves. This study aimed to perform the drying of mint leaves and to experimentally specified the effective diffusion coefficient, activation energy, and heat and mass transfer coefficients values throughout the drying process. Mint leaves were dried using a laboratory-scale dryer with three different drying temperatures (30, 40, and 50°C) and three different chamber pressures (50, 60, and 70 kPa). As a result, heat transfer coefficients varied from 0.3347 to 0.3353 W/m2K, and mass transfer coefficients varied from 3.33 × 10−10 to 2.27 × 10−9 m/s for different drying conditions. The effective moisture diffusivity during drying varied from 5.01 × 10−14 to 4.80 × 10−13 m2/s. The activation energy for mint leaves during drying varied from 79.07 to 76.44 kJ/mol at different drying temperatures. Practical applications Drying is an energy-intensive process that involves simultaneous heat and mass transfer. In this study, the heat and mass transfer coefficients of mint leaves at different drying temperatures and pressures were studied. In order to optimize the drying process, the heat and mass parameters of the product must be fully understood. Understanding these parameters can easily provide a basis for designing dryers with the best energy saving.

Characterization of Effective Diffusion within Viscoelastic Fluids with Elastic Instabilities

We considered effective diffusion, characterized by magnitudes of effective diffusion coefficients, in order to quantify mass transport due to the onset and development of elastic instabilities. Effective diffusion coefficient magnitudes were determined using different analytic approaches, as they were applied to tracked visualizations of fluorescein dye front variations, as circumferential advection was imposed upon a flow environment produced using a rotating Couette flow arrangement. Effective diffusion coefficient results were provided for a range of flow shear rates, which were produced using different Couette flow rotation speeds and two different flow environment fluid depths. To visualize the flow behavior within the rotating Couette flow environment, minute amounts of fluorescein dye were injected into the center of the flow container using a syringe pump. This dye was then redistributed within the flow by radial diffusion only when no disk rotation was used, and by radial diffusion and by circumferential advection when disk rotation was present. Associated effective diffusion coefficient values, for the latter arrangement, were compared to coefficients values with no disk rotation, which were due to molecular diffusion alone, in order to quantify enhancements due to elastic instabilities. Experiments were conducted using viscoelastic fluids, which were based on a 65% sucrose solution, with different polymer concentrations ranging from 0 ppm to 300 ppm. Associated Reynolds numbers based on the fluid depth and radially averaged maximum flow velocity ranged from 0.00 to 0.5. The resulting effective diffusion coefficient values for different flow shear rates and polymer concentrations quantified the onset of elastic instabilities, as well as significant and dramatic changes to local mass transport magnitudes, which are associated with the further development of elastic instabilities.

Multiple-perspective research on the spatial distribution of full-size aerobic granular sludge in wastewater treatment

With the further application of aerobic granular sludge (AGS), the granules specific morphological and structural assessment is more essential. Full-size AGS was evaluated from multiple-perspective of mass transfer performance, spatial structure and specific morphology. The results demonstrated that AGS with 2–3 mm particle size had the best performance in all aspects. Effective diffusion coefficient (De) values of ammonia nitrogen and oxygen for 2–3 mm AGS was 0.945 × 10−9 m2/s and 0.678 × 10−9 m2/s respectively, which was higher than other particle size. Pore distribution and specific surface area revealed the differences in full-size AGS. Excellent development of 2–3 mm AGS on mesopores and macropores provided a pathway for the diffusion of NH4+-N and O2. Its specific surface area was significantly higher than other granules, reaching 151.293 m2/g, which contributed to the adsorption of the substrate. Digital holographic microscopy (DHM) images were applied firstly to observe full-size AGS without staining, indicating the 2–3 mm AGS had the highest bacterial activity. Confocal laser scanning microscopy (CLSM) images showed a good distribution of extracellular polymeric substances (EPS) and cells in AGS. By optimizing the proportion of 2–3 mm AGS in all particles, the efficiency and stability of the AGS system is expected to be greatly improved.

A Modeling Study for Moisture Diffusivities and Moisture Transfer Coefficients in Drying of “<i>Violet de Galmi</i>” Onion Drying

In the present work, the mass transfer characteristics, namely moisture diffusivity and moisture transfer coefficient of “Violet de Galmi” variety of onions were evaluated using the analytical model. Onions were dried in a single layer at different temperatures (40℃, 50℃, 60℃, and 70℃) and for a relative humidity of drying air of 20%. The results showed a reasonably good agreement between the values predicted by the correlation and the experimental observations. This model computed the Biot number, effective moisture diffusivity, and mass transfer coefficient. Effective diffusion coefficient values are obtained between 0.2578 × 10-9 m2·s-1 and 0.5460 × 10-9 m2·s-1. Mass transfer coefficients of “Violet de Galmi” onion drying vary between 3.37 × 10-7 m·s-1 and 13.38 × 10-7 m·s-1. Numbers of mass transfer Biot are found between 0.9797 and 2.9397. The activation energy Ea is 31.73 kJ·mol-1.

Unique Eu(III) transport selectivity seen using a supported liquid membrane containing a diglycolamide dendrimer ligand

ABSTRACT Dendrimers are exotic multi-functional ligands and are expected to give rise to better extraction/transport results as compared to the mono-functional ligands. Diglycolamide (DGA) based dendrimers are scarcely reported and literature on their transport studies are very limited. Transport of Am(III) and Eu(III) across a PTFE (polytetrafluoroethylene) based flat sheet supported liquid membrane containing a generation 1 dendrimer of tris(2-aminoethyl)amine (TREN), containing six diglycolamide (DGA) pendent arms (termed as TREN-G1-DenDGA) was investigated from nitric acid feed solutions. The transport studies involved 5.75 × 10−4 M ligand solution in 5% isodecanol modified n-dodecane. Am(III) transport was slower than that of Eu(III) under identical conditions. The transport of both Am(III) and Eu(III) increased with increasing nitric acid concentration from 1 to 6 M HNO3 suggesting a solvation extraction mechanism with nitrate ions playing a significant role. A unique preferential Eu(III) transport over Am(III) was seen at 3 M HNO3 with a transport selectivity factor (ratio of permeability coefficient values) of 6.2 which decreased upon changing the acid concentration. Carrier ligand concentration also played a significant role in transport selectivity. Membrane parameters such as permeability coefficient and effective diffusion coefficient (D eff) values were determined experimentally. The liquid membrane stability studies were also carried out.

Impact of process parameters on drying behaviour, mass transfer and quality profile of refractance window dried banana puree

Refractance Window (RW) is a relatively new drying technique for producing dried powders, slices or leathers from fruits and vegetables. In the present study, the effect of temperature (70, 80 and 90 °C) and thickness of puree (2 and 3 mm) on drying characteristics, mass transfer and quality attributes of RW dried banana puree were investigated. Results showed that drying at 90 °C reduced drying time (~61–64%) and energy consumption (~30–44%), as compared to drying at a lower temperature (70 °C) for both the thickness. The effective diffusion coefficient (Deff) values obtained (2.89 × 10−9 to 8.84 × 10−9 m2/s) using Dincer and Dost analytical approach had higher R2 (0.980–0.991) and lower RMSE (0.029–0.053) values. RW drying at 90 °C resulted in higher ascorbic acid retention (~76–78%) with the least total colour change (3.4–6.9) compared to other studied conditions. Besides, retention of total phenolic (10.3 mg GAE/g dm) and flavonoid contents (3.4 mg QE/g dm), as well as antioxidant capacity (58.8 mM TE/g dm), were also better in samples dried at 90 °C. The study suggested that drying at a higher temperature during RW not only reduces drying time but also improves retention of quality attributes.

Experimental and Numerical modeling on dye adsorption using pyrolyzed mesoporous biochar in Batch and fixed-bed column reactor: Isotherm, Thermodynamics, Mass transfer, Kinetic analysis

Adsorbents derived from agro-waste can be a feasible substitute for the synthesis of the activated biochar for the removal of pollutants from their aqueous solution. ZnCl2 was used to activate the pyrolyzed biochar, derived from sugarcane bagasse. Physical characterizations of synthesized activated pyrolyzed biochar were analyzed by XRD, FTIR, and SEM. From the BET analysis, the surface area of activated pyrolyzed biochar was determined as 51.733 m2/g. Investigations on the adsorption of Malachite Green (MG) dye using activated biochar was studied in batch and fixed-bed system. Isotherm study suggested that the Freundlich isotherm model (R2=0.9955) provided the best fit to the equilibrium adsorption and the biosorption capacity obtained as 90.1mg/g at 30°C. Experimental data showed well in accordance with the pseudo-second-order kinetic model. The thermodynamic study indicated the spontaneous and exothermic nature of reactions involved. Boyd's film diffusion model was used with the kinetic data of the Batch adsorption experiment to evaluate the diffusion mechanism and rate-limiting step. The derived value of the average effective diffusion coefficient (De) was 0.014 × 10−7 m2/s. The Yoon-Nelson and Thomas model ware well fitted with the experimental data obtained from column adsorption study. The dispersion coefficient and mean pore velocity for adsorbent columns were estimated using the breakthrough curves at various experimental conditions. Adsorption Kinetic parameters for MG dye were estimated using the solute transport model by combining convective flow and hydrodynamic dispersion with a two-site adsorption model and coupled with inverse modeling of breakthrough curves.

DRYING KINETICS OF REDUCED FAT WHITE CHEESE DRIED BY DIFFERENT METHODS

In the current study, three different drying methods, including hot air drying (50, 60, 70 °C and 1.8 m/s), microwave drying (180, 360, 540 W) and freeze-drying (0.2, 0.15, 0.1 mbar) were experimentally studied and the drying kinetics of reduced-fat white cheese (RFWC) were determined. Microwave drying process time was significantly shorter than hot air drying and freeze-drying for RFWC. Semi-empirical models were applied to determine the most appropriate drying model targeting the highest R2 and the lowest RMSE and χ2 values representing the drying kinetics of RFWC. The effective diffusion coefficient values for different drying methods varied from 1.521 x 10-9 to 4.432 x 10-8 m2/s. Through increasing the temperature, microwave power, and vacuum pressure, effective diffusion coefficient values increased. The activation energy values were determined as 12.421 kJ/mol for hot air drying and 5.599 W/g for microwave drying.

Drying kinetics behavior of turkey breast meat in different drying methods

AbstractIn this study, turkey breast meat samples were dried with hot air (60, 75, 90°C), microwave (180, 360, 540 W) and freeze (0.1, 0.15, 0.2 mbar) drying and parameters related to the drying kinetics of turkey breast meat were investigated. Although a constant drying rate was not observed for all drying methods, the drying process occurred only during the falling drying rate period. Microwave drying process times were lower than those of hot air and freeze drying because of volumetric heating. Drying times decreased by increasing temperature, power and vacuum pressure. Kinetic parameters were determined by using the semi‐empirical models of 2. Fick's diffusion equation. Two terms, Logarithmic and Page models were found to be better for hot air, microwave and freeze drying, respectively. In addition, the effective diffusion coefficient values were found in range of 2.03–2.53 × 10−10, 27.89–103.96 × 10−10 and 2.99–3.36 × 10−10 m2/s for hot air, microwave and freeze drying, respectively. Effective diffusion coefficients increased in direct proportion with temperature, microwave power and vacuum pressure. The activation energy obtained by the modified Arrhenius equation were 7.481 kJ/mol to 6.043 W/g for hot air and microwave drying respectively.Practical ApplicationsThe drying kinetics behavior of foods is important for protecting the final product quality, determining the process method and optimizing the process parameters in the food industry. Despite the availability of many drying kinetics studies, meat products exhibit different behaviors during the drying process due to their structure and composition. The drying kinetics behavior of turkey breast meat with different drying techniques was investigated in this study. When the effective diffusion coefficient and activation energy data were considered, it was noticed that microwave drying provided a faster and more effective drying process. The moisture content and water activity values, which are very important especially for meat products, showed that freeze drying provided a more reliable product by reducing the moisture content and water activity of final product more than other drying methods.

CH4 and CO2 sorption and diffusion carried out in various temperatures on hard coal samples of various degrees of coalification

The aim of the study was to analyse the effect of temperature on the sorption and diffusion of CO2 and CH4 on hard coal. Four coal samples, characterized by various degrees of coalification, were used in the research. The sorption measurements were carried out in three temperature values: 278 K, 313 K and 353 K and for the consecutive pressure values of 1 bar, 5 bar and 15 bar. Langmuir's sorption capacity in relation to CH4 and CO2 was the highest for the coal with the lowest degree of coalification and was 32.15 cm3/g and 76.4 cm3/g respectively. The lowest Langmuir sorption capacity in relation to CH4 and CO2 were obtained for medium-rank coal (19.23 cm3/g and 29.26 cm3/g) and high-rank coal (20.33 cm3/g and 32.89 cm3/g). The temperature growth resulted in a reduction of the sorption capacity of coal in relation to CH4 and CO2, and that decline was exponential in relation to temperature. The absolute decreases in the total sorption capacity were from 0.03 cm3/g to 0.21 cm3/g in relation to CH4, and from 0.10 cm3/g to 0.51 cm3/g in relation to CO2, per 1 K temperature increase. Within the measurement temperature range of 278–353 K, no „critical temperature point”, above which there is no reduction in CH4 and CO2 sorption, was observed. An increase in the temperature pushed up the values of the effective diffusion coefficients, in relation to CH4 by more than one order of magnitude, and in relation to CO2 by approximately four times. A decrease in the selectivity of CO2/CH4 was also observed along with the coal rank. The ratio of effective diffusion coefficient values DeCO2/DeCH4 for all the investigated coal samples declined strongly along with temperature growth.

Anisotropic diffusion assessment in salmon (salmo salar) composite muscle tissue: Theoretical and image-processing experimental approaches

A simple method to study the diffusion of a probe molecule into muscle tissue, which considers real composite architecture and anisotropy, was proposed. An anisotropic diffusion study of methylene blue (MB) as a probe molecule into the composite muscle tissue of salmon (Salmo salar) was performed using an image-processing technique. The concentration profile was determined in the middle sagittal plane by considering the muscle fiber orientation angle (θ). The mean value of the angle was θ=31±1.2°, and the fractional anisotropy values showed an anisotropic behavior for all samples tested. The presence of the discontinuity between muscle and connective tissue was characterized by the distribution coefficient. The simulation using the generalized minimum residual method iterative solver in COMSOL Multiphysics™ software described the anisotropic condition of the tissue with root mean square values of less than 27%. Significant differences were found in effective diffusion coefficient values between the muscle and connective tissue at 2°C (p-value<0.05). Further studies may consider other diffusing molecules and muscle tissues.