Effective Diffusion Coefficient Deff Research Articles

Effects of Carbon Deposition on Deuterium Plasma-Driven Permeation Through Tungsten-Coated RAFM Steel

In steady-state operation of fusion reactors, eroded materials and contaminations, especially carbon (C), may deposit on the surface of plasma-facing components. In this work, the effects of C deposition on hydrogen isotope permeation behavior through tungsten (W)–coated reduced activation ferritic/martensitic (RAFM) steel were systematically investigated by plasma-driven permeation (PDP) measurements in the temperature range of 633 to 893 K. A C deposition layer with thickness of ~200 nm was prepared by magnetron sputtering to simulate the formation of C impurities in the first-wall area of tokamaks. The implantation depth of incident deuterium (D) ions was estimated to be <10 nm at incident energy of 114 eV. Deuterium effective diffusion coefficients (Deff’s) for W-coated RAFM steel with/without a C layer were obtained. It was found that the C layer tended to increase Deff in the low-temperature region of ~675 to 820 K. At high temperature, however, Deff was measured be lower than that without a C layer. Nevertheless, the addition of a C layer had no significant effect on Deff compared to the W coating alone with respect to bare RAFM steels. For steady-state D-PDP flux, it was found that the C layer significantly decreased D permeation flux at low temperature. But, the permeation flux difference between the samples with/without a C layer became smaller with increasing temperature, indicating that the influence of C deposition on D permeation was negligible at high temperature. Similar D-PDP behavior was detected as increasing the incident ion flux by means of increasing plasma discharge power. Surface reemission of absorbed D as well as the D concentration gradient throughout the sample was found to be influenced by C deposition; therefore, D permeation flux changed correspondingly.

In vitro assessment of skin permeation properties of enzymatically derived oil-based fatty acid esters of vitamin C.

Current topical formulations containing vitamin C face limitations in therapeutic effectiveness due to the skin's selective properties that impede drug deposition. Consequently, the widespread use of toxic and irritating chemical permeation enhancers is common. Hereby, we investigated enzymatically derived fatty acid ascorbyl esters (FAAEs) obtained using natural oils for their skin permeation properties using the Strat-M® skin model in a Franz cell diffusion study. By evaluating various cosmetic formulations without added enhancers, we found that emulgel is most suitable for enhancing the cutaneous and transdermal delivery of FAAEs. Furthermore, medium-chain coconut oil-derived FAAEs exhibited faster diffusion rates compared to sunflower oil-based FAAEs with long-side acyl residues, including the commonly applied ascorbyl palmitate. Experimental data were successfully fitted using the Peppas and Sahlin model, which accounted for a lag phase and the combined effect of Fickian diffusion and polymer relaxation. In the case of long-chain esters, the lag phase was prolonged, and the calculated effective diffusion coefficients (Deff) were lower compared to medium-chain FAAEs. Accordingly, the highest Deff value was observed for ascorbyl caprylate, being even 60 times higher than for ascorbyl palmitate. These results suggest the emerging potential of emulgel with incorporated coconut oil-derived FAAEs for efficiently delivering vitamin C into the skin.

Drying kinetics and water adsorption properties of jalapeño pepper seeds (Capsicum annuum L.): A study aiming at their recovery and integral exploitation

Drying kinetics (DK) and water adsorption isotherms (WAI) of Jalapeño pepper seeds (JPS) were evaluated and modeled at different temperatures. The proximate composition, flavonoid content (FC), and total phenolic compounds (TPC) of JPS were determined. Furthermore, JPS oil was extracted and characterized. Five mathematical models were tested to describe the JPS drying kinetics at five temperatures (40–80 °C) as well as the effective diffusion coefficient (Deff) and activation energy (Ea) were calculated. The WAI of the JPS was determined at nine temperatures (8–72 °C) and five mathematical models were fitted to JPS adsorption data. Thermodynamic properties were also estimated. The JPS presented TPC (30.9 mg GAE/g), FC (17.4 mg catechin equivalents/g), fibers (54.8 g/100 d.b.), lipids (22.2 g/100 d.b.), and proteins (15.5 g/100 d.b.). The study on drying kinetics pointed out that the Weibull model best fitted to drying kinetics data, Deff increased directly to temperature, and the Ea = 30.302 kJ/mol. The GAB model presented good accuracy in describing the WAIs that were classified as BET Type II. The net isosteric heat of adsorption and differential entropy decreased with increasing EMC. Enthalpy-entropy compensation theory was corroborated and characterized the adsorption of JPS as enthalpy-driven and spontaneous.

Drying kinetic, thermodynamic and quality analyses of infrared drying of truffle slices.

Kinetic and thermodynamic parameters are the most important part for making a suitable tool for drying agricultural products. Moreover, calculation of the energy required for the drying of product, the properties of the rehydration ratio, the food appearance changes, and the evaluation of the microstructure of food are crucial. Since the thermodynamic properties of truffle slices have not yet been reported, this study aims to establish a mathematical model to describe drying process of agriculture product, evaluate the effective moisture diffusion coefficient (Deff), determining the activation energy (Ea) to elucidate the thermodynamic characteristics, measure color characteristics, and rehydration ratio (RR) during the drying process of truffle slices. Truffle slices were dried in an infrared (IR) dryer at four temperatures of 50-80°C and two thicknesses of 0.5 and 1cm. The best model to describe the drying process of truffle slices was Midilli etal.'s model. The value of Deff, SEC, and RR were in the range of 3.06 × 10-8 to 2.48 × 10-7 m2/s, 79.68-191.271kWh/kg, and 5.99-7.49, respectively. The Deff of truffle slices increased with the above-mentioned parameters of the samples. The Ea obtained was 26.62-27.43kJ/mol. The results indicated that enthalpy and entropy decreased with increasing drying temperature, while Gibbs free energy improved. The enthalpy, entropy, and Gibbs free energy values changed between 24.48-25.28kJ/mol, -130.47 to -122.63 J/mol °K, and 63.97-70.17kJ/mol, respectively. In addition, the results of color attributes decreased with increasing temperature, while chroma oppositely increased.

Synthesis of ultrathin hybrid membranes via the co-polymerization of acrylic acid, styrene and molybdenum disulfide and their high adsorption selectivity for lead(II) in the mixture of metal ions

Lead(II) is a potential carcinogen of heavy-metal ions (HIs). With the wide application of Pb-bearing products including lead alloy products, and new-energy lead-ion batteries, lead pollution has become a tricky problem. To solve such a difficulty, novel ultrathin MoS2-vinyl hybrid membranes (MVHMs) with a “spring” effect were synthesized via co-polymerization of acrylic acid, styrene and molybdenum disulfide (MoS2) and their adsorptions for HIs were explored. The “spring” effect derived from the interaction between the tendency of the short polyacrylic acid (PAA) chain connected with MoS2 to spread outward and the coulomb force between layers from MoS2 (s-MoS2), which enlarge the spacing of MoS2 layers without changing the number of layers after membrane formation, which changes the swelling membrane to a dense membrane and reduces the original thickness from 0.5 cm to 0.011 mm in the thickness direction. The adsorption experiment revealed that these MVHMs had super adsorption performance and high selectivity for Pb2+ by comparison with other five metal ions: Cu2+, Cd2+, Ni2+, Cr3+ and Zn2+. Especially, the adsorption quantity of MVHMs for Pb2+ could approach 2468 mg/g and the maximum adsorption ratio of qe[Pb2+]/qe[Cu2+] can reach 10.909. These values were much larger than the data obtained with the adsorbents reported in the last decade. A variety of models are applied to evaluate the effect of ionic groups. It was confirmed that –COOH plays a key role in adsorption of HIs and s-MoS2 also has a certain contribution. Conversely, ion exchange plays only a minor role during the period of adsorption process. Effective diffusion coefficient (Deff) of Pb(II) had the largest values among these metal ions. Hence, these hybrid membranes are promising adsorbents for the removal of Pb2+ from water containing various ions.

Mass transfer of solute in an oscillating flow in a two-dimensional channel

The effective diffusion of a solute in a rectangular two-dimensional channel is experimentally studied. We experimentally examine the effective diffusion of Rhodamine B dissolved in water oscillating in a rectangular Hele–Shaw cell. The concentration of Rhodamine B in water is measured by the intensity of its fluorescence emission. In particular, we consider two problems: (i) effective diffusion of solute in water oscillating in a two-dimensional rectangular channel (Hele–Shaw cell) and (ii) effective diffusion of solute in pores between monosized hard spheres randomly packed in a rectangular Hele–Shaw cell. It is revealed that the rate of solute mass transfer exceeds the molecular diffusion rate in both cases. It has been demonstrated that when water oscillates between parallel walls, diffusion is accelerated by Taylor dispersion with the effective diffusion coefficient Deff exceeding the molecular diffusion coefficient Dm by 1–2 orders of magnitude. The effective diffusion coefficient Deff depends only on the relative amplitude but not on the frequency of the fluid oscillations in the studied range of frequencies and amplitudes. When the fluid oscillates in the pores of the porous medium, solute transport is faster than in the case of Taylor dispersion. Here, the effective diffusion coefficient depends on both the frequency and amplitude of oscillations. The analysis shows that the experimental data obtained at various frequencies and amplitudes of oscillations are consistent with the relation Deff/Dm∼Pe2 (Pe is the Peclet number). We suggest that the enhanced solute mass transfer is associated with the time-averaged fluid flows that arise due to spatial heterogeneity of the amplitude of water oscillations in the pores between randomly packed hard spheres.

Theoretical analysis of the effect of isotropy on the effective diffusion coefficient in the porous and agglomerated phase of the electrodes of a PEMFC

In polymer membrane fuel cells (PEMFC), the pore microstructure and the effective diffusion coefficient (Deff\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$D_{eff}$$\\end{document}) of the catalytic layer have a significant impact on the overall performance of the fuel cell. In this work, numerical methods to simulate PEMFC catalytic layers were used to study the effect of isotropy (Ixy\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$I_{xy}$$\\end{document}) on the Deff\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$D_{eff}$$\\end{document}. The proposed methodology studies reconstructed systems by Simulated Annealing imaging with different surface fractions of microstructures composed by two diffusive phases: agglomerates and pores. The Deff\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$D_{eff}$$\\end{document} is determined numerically by the Finite Volume Method solved for Fick's First Law of Diffusion. The results show that the proposed methodology can effectively quantify the effect of isotropy on the Deff\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$D_{eff}$$\\end{document} for both diffusion phases. Two trends were obtained in the magnitude of the Deff\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$D_{eff}$$\\end{document} concerning the change in isotropy: (1) an analytical equation is proposed in this article for Deff≥5%D0\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$D_{eff} \\ge 5\\% D_{0}$$\\end{document} and (2) numerical solutions are determined for Deff<5%D0.\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$D_{eff} < 5\\% D_{0} .$$\\end{document} In our analytical equation are both a lineal and a logarithmic sweep. When the surface fraction is ∅=\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\emptyset =$$\\end{document} 50%, the Deff\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$D_{eff}$$\\end{document} decreases more linearly than ∅=10%\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\emptyset = 10\\%$$\\end{document} at the beginning of the isotropy change, which indicates that small changes in isotropy in the particulate material modify it drastically; under these conditions the diffusion coefficient in the pore is predominant. (3) When the surface fraction is less than 50%, the Deff\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$D_{eff}$$\\end{document} decreases more exponentially at the beginning and more linearly at the end of the isotropy change, which shows that small isotropy changes in the bar-aligned material drastically alter it. In this trend, diffusion in the agglomerate is less affected by isotropy. The proposed methodology can be used as a design tool to improve the mass transport in porous PEMFC electrodes.

Mass transfer research on solid-liquid separation of extracted coal tar residue based on diffusion model

A large amount of coal tar residue (CTR) produced in the process of coal coking and tar processing is recognized as hazardous industrial waste with a high carbon content and strong carcinogenic polycyclic aromatic hydrocarbons. Through solvent extraction, CTR can be separated into economically valuable tar and fixed carbon, and waste recycling can be realized. In this paper, a mathematical model of CTR solid-liquid extraction is established based on a diffusion model and experiments, and the mass transfer law, mass transfer equation, and influence of different conditions of solid-liquid separation of CTR from toluene extraction are studied. First, the empirical formula is used to derive the change in the mass transfer coefficient kf outside the particles during extraction, and the kf gradually decreases as the extraction progresses. The particle swarm optimization is used to obtain the best effective diffusion coefficient Deff, inside the particles, which is 9.65 × 10−14 m2/s. The effective diffusion coefficient, Deff, was determined and corrected based on experimental data. A second-order function was fitted to describe the variation of Deff with temperature. MATLAB software was used to solve the model the concentration change law and extraction law during extraction were obtained. According to the model simulation, the influence of different conditions such as agent residue ratio, stirring speed, particle radius, and temperature on the extraction process is calculated.

Simulation Study of Li-Ion Batteries Considering the Porosity and Tortuosity of Separator

Lithium-ion batteries (Li-ion batteries) offer high energy and power densities, making them the most widely used battery technology for energy storage in various applications such as grid-scale, automotive, and electronic devices. One of the critical components of a Li-ion battery is the porous separator which can impair performance at high charge/discharge rates. Separator has a considerable influence on the transport of lithium ions. The structural properties of the separator, such as porosity and tortuosity can have a significant impact on heat generation and polarization of lithium concentration as well as the current density distribution inside the separator. The porosity of a porous separator is a well-defined feature that may be easily determined. In contrast, the tortuosity of separators, is more difficult to assess.To model and calculate the separator properties, in this study, the simulated structural separator was constructed by numerical analysis1 based on actual separator structure from Cryo-FIB-SEM. The numerical simulation of the ion-transport model for concentrated electrolyte solutions using the model developed by Newman et al2. Different structures of separators provided different behaviors at different charge/discharge rates. To evaluate overall battery performance, using the previously reported structural information3,4, lithium nickel manganese cobalt oxides (NCM), 1.0 M LiPF6 solution in EC-DEC solvent, and graphite were used for the cathode, electrolyte, and anode, respectively.This work simulated and compared three different separator structures: foam, non-woven fabric, and stretched structure with three different constant charging rate (C-rate) conditions (1 C, 5 C and 8 C). The calculation of porosity and tortuosity has been done for through-plane model. The higher C-rate will increase the heat generation significantly and affect the battery`s thermal behavior. The tortuosity and porosity have correlation on the effective ionic conductivity σeff = (ε/τ)*σ and effective diffusion coefficient Deff = (ε/τ)*D. Higher separator porosity can effectively increase the effective diffusion coefficient, hence improving mass transfer and reducing resistance. The separator with uniform porosity and smaller tortuosity showed smaller diffusion polarization because Li+ can be transported easily and uniformly in it, leading to lower heat generation even in high C-rate condition. The model developed in this study is intended to be valuable in understanding behavior of porous separators and optimizing the battery design.Acknowledgement: This research was carried out under the project (Grant Number JPMJMI21G4) supported by the JST-Mirai Program, Japan.

Detailed analysis of the effective and intra-particle diffusion coefficient of proteins at elevated pressure in columns packed with wide-pore core-shell particles

To determine the efficiency that can be obtained in a packed-bed liquid-chromatography column for a particular analyte, a correct determination of the molecular and effective diffusion coefficients (Dm and Deff) of the analyte is required. The latter is usually obtained via peak parking experiments wherein the flow is stopped. As a result, the column pressure rapidly dissipates and the measurement is essentially conducted at ambient pressure. This is problematic for analytes whose retention depends on pressure, such as proteins and potentially other large (dipolar) molecules. In that case, a conventional peak parking experiment is expected to lead to large errors in Deff. To obtain a better estimate ofDeff, the present study reports on the use of a set-up enabling peak parking measurements under pressurized conditions. This approach allowed us to report, for the first time, Deff for proteins at elevated pressure under retained conditions. First, Deff was determined at a (average) pressure of about 105 bar for a set of proteins with varying size, namely: bradykinin, insulin, lysozyme, β-lactoglobulin, and carbonic anhydrase in a column packed with 400 Å core-shell particles. The obtained data were then compared to those of several small analytes: acetophenone, propiophenone, benzophenone, valerophenone, and hexanophenone. A clear trend between Deff and analyte size was observed. The set-up was then used to determine Deff of bradykinin and lysozyme at variable (average) pressures ranging from 28 bar to 430 bar. These experiments showed a decrease in intra-particle and surface diffusion with pressure, which was larger for lysozyme than bradykinin. The data show that pressurized peak parking experiments are vital to correctly determine Deff when the analyte retention varies significantly with pressure.

Comprehensive analysis of the effective and intra-particle diffusion of weakly retained compounds in silica hydrophilic interaction liquid chromatography columns

A detailed analysis of intra-particle volumes and layer thicknesses and their effect on the diffusion of solutes in hydrophilic interaction liquid chromatography (HILIC) was made. Pycnometric measurements and the retention volume of deuterated mobile phase constituents (water and acetonitrile) were used to estimate the void volume inside the column, including not only the volume of the mobile phase but also part of the enriched water solvent acting as the stationary phase in HILIC. The mobile phase (hold-up) volume accessible to non-retained components was estimated using a homologous series approach. The joint analysis of the different approaches indicated the formation of enriched water layers on the hydrophobic silica mesopore walls with a thickness varying significantly with mobile phase composition. The maximal thickness of the enriched water layers, which corresponded to the minimum void volume accessible to unretained solutes, marked a transition in the retention behavior of the studied analytes. Discrepancies between deuterated solvent measurements and pycnometry were explained by the existence of an irreplaceable water layer adsorbed on the silica surface. Regarding the diffusion behavior in HILIC, peak parking experiments were used to interpret the influence of the acetonitrile content on the effective diffusion coefficient Deff. A systematic decrease in Deff and molecular diffusion Dm was observed with decreasing acetonitrile concentration, primarily attributed to variations in mobile phase viscosity. Notably, Deff/Dm remained nearly unaffected by variations in mobile phase composition. Finally, the effective medium theory was used to make a comprehensive analysis of Dpart/Dm to study the contribution to band broadening when the solute resides in the mesopores. The obtained data unveiled a curvature with a minimum corresponding to conditions of maximum water-layer thickness and retention. For the weakly retained compounds (k’ < 0.5) the Dpart/Dm-values were found to be relatively high (order of 0.35-0.5), which directly reflects the high γsDs/Dm-values that were observed (order 0.35-7).

Hydrogen Diffusion in Nickel Superalloys: Electrochemical Permeation Study and Computational AI Predictive Modeling.

Ni-based superalloys are materials utilized in high-performance services that demand excellent corrosion resistance and mechanical properties. Its usages can include fuel storage, gas turbines, petrochemistry, and nuclear reactor components, among others. On the other hand, hydrogen (H), in contact with metallic materials, can cause a phenomenon known as hydrogen embrittlement (HE), and its study related to the superalloys is fundamental. This is related to the analysis of the solubility, diffusivity, and permeability of H and its interaction with the bulk, second-phase particles, grain boundaries, precipitates, and dislocation networks. The aim of this work was mainly to study the effect of chromium (Cr) content on H diffusivity in Ni-based superalloys; additionally, the development of predictive models using artificial intelligence. For this purpose, the permeability test was employed based on the double cell experiment proposed by Devanathan-Stachurski, obtaining the effective diffusion coefficient (Deff), steady-state flux (Jss), and the trap density (NT) for the commercial and experimentally designed and manufactured Ni-based superalloys. The material was characterized with energy-dispersed X-ray spectroscopy (EDS), atomic absorption, CHNS/O chemical analysis, X-ray diffraction (XRD), brightfield optical microscopy (OM), and scanning electron microscopy (SEM). On the other hand, predictive models were developed employing artificial neural networks (ANNs) using experimental results as a database. Furthermore, the relative importance of the main parameters related to the H diffusion was calculated. The Deff, Jss, and NT achieved showed relatively higher values considering those reported for Ni alloys and were found in the following orders of magnitude: [1 × 10-8, 1 × 10-11 m2/s], [1 × 10-5, 9 × 10-7 mol/cm2s], and [7 × 1025 traps/m3], respectively. Regarding the predictive models, linear correlation coefficients of 0.96 and 0.80 were reached, corresponding to the Deff and Jss. Due to the results obtained, it was suitable to dismiss the effect of Cr in solid solution on the H diffusion. Finally, the predictive models developed can be considered for the estimation of Deff and Jss as functions of the characterized features.

Evaluation of infrared drying for okra: Mathematical modelling, moisture diffusivity, energy activity and quality attributes

Okra (Hibiscusesculentus L.) was dried using an infrared drier at radiation intensities of 0.167, 0.235, and 0.520 W/cm2 and air velocities of 0.3, 0.5, and 0.7 m/s to determine its thin-layer drying characteristics and quality parameters. Okra dried during falling rates, and drying time was reduced with rising infrared intensity and declining air velocity. Eleven alternative numerical simulations fit the data gathered through the drying kinetics. The equation developed by Midilli et al. was determined to be the most useful model for illuminating okra's drying behavior. Fick's diffusion model was used to derive effective moisture diffusion coefficients (Deff), which ranged from 2.89 to 12.23 ×10−10 m2/s for the drying conditions. The rehydration ratio improved with increasing air velocity and reduced with higher infrared radiation intensity. In contrast, the shrinkage ratio increased with raised infrared radiation intensity and reduced with higher air velocity. The overall color difference between fresh and dried okra increased as air velocity and radiation intensity increased.

Effect of Different Drying Systems on Drying Performance of Maraş Green Pepper (C.annum)

Drying is the simultaneous transfer of heat and mass, which is defined as the reduction of moisture in food. The aim of the study the drying performances of refractance window drying (95°C), fluidized bed drying (95°C, 2m3/m air velocity), and convective drying (95°C) were examined in the drying of Maraş green pepper (C.annuum). Drying performance was evaluated for effective diffusion coefficient (Deff), activation energy (Ea), Chroma (C) and total color change (ΔE). Drying curves were obtained by recording sample weights in 10-min periods. For the refractance window drying, fluidized bed drying and convective drying the time for the samples to reach 6-7% humidity level according to the wet base was found to be 70, 80 and 110min, and the effective diffusion coefficient was 6.49x10-10, 5.68x10-10 and 4.87x10-10 m2/s the activation energy was 53.54, 54.65 and 55.93kJ/mol, respectively. When the color properties are examined the Chroma value was determined as 18.23, 8.85 and 4.80 and the total color as 15.42, 26.29 and 30.33, respectively. It was seen that the closest value to the fresh product was in the samples dried with a refractance window drying. In the study, it was concluded that the use of a refractance window drying shortened the drying time by 14-36%, increased the effective diffusion coefficient, provided drying with lower activation energy, and better preserved the color quality in the production of dried Maraş green pepper.

Quantifying of the Best Model for Prediction of Greenhouse Gas Emission, Quality, and Thermal Property Values during Drying Using RSM (Case Study: Carrot)

The aim of this study is to use the response surface methodology (RSM) to mathematically model the response parameters and emission of greenhouse gases (GHG) and optimize the drying variables for a carrot dried with the microwave method using various pretreatments. To this end, the influence of the drying parameters (independent), such as microwave power and slice thickness dried by two pretreatments of ultrasonication at 30 °C for 10 min and blanching at 70 ℃ for 2 min, was explored on the dependent (response) parameters including the thermal properties (drying time, effective moisture diffusion coefficient (Deff), specific energy consumption, energy efficiency, quality features (color changes and shrinkage), and GHG emission (including CO2 and NOx). It should be mentioned that the emission of GHG was determined based on the energy consumption of various types of power plants such as the gas turbine steam power turbine, and combined cycle turbines using various fuels such as natural gas, heavy oil, and gas oil. The results indicated that the ultrasonication and blanching pretreatments can decrement the drying time (linearly), energy consumption (linearly or quadratically), shrinkage(quadratically), and color changes(quadratically) and enhance the Deff (linearly) and energy efficiency (linearly or quadratically) in all samples with R2 &gt; 0.86. Moreover, the shortest drying time (42 min), lowest SEC (9.51 MJ/kg), and GHG emission ((4279.74 g CO2 in the combined cycle turbines plant, and 18.16 g NOX in the gas turbine plant) with natural gas for both plants) were recorded for the samples pretreated with blanching while the lowest color changes (13.69) and shrinkage (21.29) were observed in the ultrasonicated samples. Based on the optimization results, a microwave power of 300 W and steam power turbine of 2 mm were the best variables with a desirability of about 80% which resulted in the highest-quality products at the lowest GHG emission.

Effect of combined convective hot air and far-infrared radiation on physic-chemical aspects of black raspberry powder produced by foam mat method

In recent years the use of hybrid drying methods has been noticed because of the improvement of the dried products quality. The effect of infrared (IR) power (0, 400, 600, and 800 W) in combination with convective hot air (60 °C, 3 m/s) on the quality properties of black raspberry pulp during foam mat drying was investigated in this study. According to the findings, increasing the IR power, (IR-CHA) had no effect on the moisture content, moisture ratio, or drying rate of the product; however, the effective moisture diffusion coefficient (Deff) was significantly increased. The effect of IR power on the physicochemical properties of black raspberry powder revealed that combining infrared with convective hot air (IR-CHA) improved the powder's flowability and total polyphenol content while decreasing its moisture content (p < 0.05). Furthermore, FESEM images revealed that the increase in IR power resulted in particles with smooth surfaces.

Ultrahigh Effective Diffusion in Oxide by Engineering the Interfacial Transporter Channels.

Mass storage and removal in solids always play a vital role in technological applications such as modern batteries and neuronal computations. However, they were kinetically limited by the slow diffusional process in the lattice, which made it challenging to fabricate applicable conductors with high electronic and ionic conductivities at room temperature. Here, we proposed an acid solution/WO3/ITO sandwich structure and achieved ultrafast H transport in the WO3 layer by interfacial job-sharing diffusion, which means the spatially separated transport of the H+ and e- in different layers. From the color change of WO3, the effective diffusion coefficient (Deff) was estimated, dramatically increasing ≤106 times and overwhelming values from previous reports. The experiments and simulations also revealed the universality of extending this approach to other atoms and oxides, which could stimulate systematic studies of ultrafast mixed conductors in the future.

Self-discharge kinetics behaviors of the Li-Si anode for thermal batteries: Modeling, quantifying and fitting analysis

Self-discharge has significant influence on the service life of thermal batteries. The kinetics process of self-discharge depends on both the structure evolution and intrinsic property of electrodes. Herein, the kinetics model to quantify the self-discharge degree of the Li-Si anode is constructed according to the structure of thermal cells. Typical operation and preparation parameters, i.e. temperature, discharge current and electrode thickness, are evaluated based on the specially designed combined-discharge scheme. Then the effective diffusion coefficients (Deff) of soluble lithium (Li0) that are affected by the three variables are calculated and fitted. The calculation results consequently confirm self-discharge process of the Li-Si anode can be described by the derived equations exactly, and then the process is demonstrated to be diffusion-controlled. Further, Deff increase at the higher temperature and larger discharge current, while decrease with the increased electrode thickness, which is analyzed by scanning electron microscope and X-ray microcomputed tomography. The entire effects on Deff can be coupled in one fitting expression based on Arrhenius equation, and the apparent activation energies decrease under the larger discharge current and smaller electrode thickness. Finally, the additional experiments were conducted to verify the accuracy of the fitting expression.

Hydrogen Embrittlement Susceptibility of Corrosion-Resistant Spring Rod Used in High-Speed Railway

The corrosion of spring steel is very important for vehicle safety. In this work, we conducted an experiment on multi-element micro-alloy composition design; the corrosion resistance of a 60Si2Mn spring was improved by adding Cr, Ni, Cu and other corrosion-resistant elements, and the corrosion resistance index (I) was increased from 3.21 to 8.62. Hydrogen embrittlement resistance was studied using a hydrogen permeation experiment and a slow strain rate tensile experiment. For this study, the following steps were performed: Firstly, the material composition was designed, and the experimental materials that met the experimental design were prepared according to the corresponding deformation and heat treatment process; secondly, the experimental materials were charged with hydrogen; and finally, conventional tensile testing, slow tensile testing and fracture morphology testing were carried out. A hydrogen permeation experiment was carried out for the materials. The result showed that, with the increase of hydrogen charging time, the hydrogen content of two steel samples increased, and the plasticity indexes such as elongation and reduction of the area appeared in three different stages which rapidly decreased, slowly declined, and then tended to balance. The uniform NbC nano precipitated phase can double the number of irreversible hydrogen traps (Nir) per unit volume, and decreased the effective hydrogen diffusion coefficient (Deff) from 1.135 × 10−10 to 6.036 × 10−11. It limited the free diffusion of hydrogen and made the immersed hydrogen harmless, thus improving the hydrogen embrittlement resistance of corrosion-resistant spring steel 60Si2Mn.

Hydrogen embrittlement behavior in the nugget zone of friction stir welded X100 pipeline steel

Hydrogen-induced damage is an inevitable challenge in pipeline safety applications, especially, the fusion welded joints owing to microstructure heterogeneity caused by welding process. In this work, X100 pipeline steel was subjected to friction stir welding (FSW) at rotation rates of 300–600 rpm under water cooling, and the relationship among the microstructure, hydrogen diffusivity, and hydrogen embrittlement (HE) behavior of the nugget zone (NZ) were studied. The NZ at 600 rpm had the highest effective hydrogen diffusion coefficient (Deff) of 2.1 × 10−10 m2/s because of the highest dislocation density and lowest ratio of effective grain boundary. The Deff decreased with decreasing rotation rate due to the decrease of dislocation density and the increase of ratio of effective grain boundary, and the lowest Deff of 1.32 × 10−10 m2/s was obtained at 300 rpm. After hydrogen charging, the tensile strength of all specimens decreased slightly, while the elongation decreased significantly. As the rotation rate decreased, the elongation loss was obviously inhibited, and ultimately a lowest elongation loss of 31.8% was obtained at 300 rpm. The abovementioned excellent mechanical properties were attributed to the fine ferrite/martensite structure, low Deff, and strong {111}//ND texture dramatically inhibiting hydrogen-induced cracking initiation and propagation.