PredicDiff™: a computational tool for the prediction of PERLs concentrations based on extractables data.

Understanding the mechanisms governing ionic transport in ceramics is important for improving the performance and durability of Solid Oxide Fuel Cells (SOFCs). Properties such as the tracer diffusivity, D* , can be measured by Isotopic Exchange Depth Profiling (IEDP) as developed by Kilner et al. [1]. This method has, so far, primarily been used to characterise the material properties of single materials; however, SOFCs are multilayer devices with solid-solid interface that may also affect transport. Some investigations into the diffusion behaviour across multiple layers using the IEDP technique have been done in thin film samples [2][3]. Profiles obtained from these studies appear to show an abrupt concentration drop at the interface between certain materials, indicating an interface which significantly impacts the diffusion behaviour (and by extension the overall cell performance). However, no attempt was made to quantify this interface effect with a theoretical modelling approach.A finite-difference model for diffusion in a system containing multiple layers with interfaces has been developed. It numerically solves Fick’s second law of diffusion with various boundary conditions. This model can be used to fit experimental data obtained from tracer diffusion SIMS data, yielding a new way of quantifying interfacial resistance. A new interfacial resistance parameter, r int , has been defined, which quantifies the resistance to diffusion across an interface.The validity of the developed method has been experimentally demonstrated in a sample consisting of a layer of lanthanum strontium cobalt ferrite (LSCF) on a gadolinium-doped ceria (GDC) substrate, both common materials in SOFCs. Initial data from tracer diffusion experiments have shown the presence of a significant concentration drop at the interface of the LSCF-GDC stack, which can be fitted to the numerical model developed by the authors. This approach could be used to measure the changing interface properties under various ageing conditions, as well as the influence of interlayers and material selection on the interfacial resistances both in SOFC and other diffusion systems with interfaces, such as solid state batteries.[1] J. A. Kilner, B. C. H. Steele, and L. Ilkov. Oxygen self-dffusion studies using negative-ion secondary ion mass-spectrometry (sims). Solid State Ionics, 12(MAR):89-97, 1984.[2] K. Develos-Bagarinao, H. Yokokawa, H. Kishimoto, T. Ishiyama, K. Yamaji, and T. Horita. Elucidating the origin of oxide ion blocking effects at gdc/srzr(y)o-3/ysz interfaces. Journal of Materials Chemistry A, 5(18):8733-8743, 2017.[3] Katherine Develos-Bagarinao, Haruo Kishimoto, Jeffrey De Vero, Katsuhiko Yamaji, and Teruhisa Horita. Effect of la0.6sr0.4co0.2fe0.8o3-delta microstructure on oxygen surface exchange kinetics. Solid State Ionics, 288:6-9, 2016.Figure: Isotope Exchange Depth Profile Data taken by linescan from an LSCF-GDC multi-layer sample. Original image data and isotopic fraction profile, as well as the corresponding fit obtained using the numerical model is shown. Figure 1

Chapter 7 - Atomic Models for Diffusion

Involved regions of the skin in patients with atopic dermatitis (AD) have been shown to have higher transepidermal water loss (TEWL), indicating a compromised skin barrier. Whether uninvolved skin also has diminished barrier characteristics is controversial. To study the penetration of sodium lauryl sulphate (SLS) into uninvolved skin of patients with AD compared with the skin of control subjects. Percutaneous penetration was assessed using the tape stripping technique on the stratum corneum (SC). Twenty patients with AD and 20 healthy subjects were exposed to 1% SLS for 4 h on the mid-volar forearm. After the end of exposure the SC was removed by adhesive tape. The amount of SLS was determined in each consecutive strip. Fick's second law of diffusion was used to deduce the diffusivity and the partition coefficient of SLS between water and the SC. The SC thickness was similar in both groups; however, the TEWL was higher in patients with AD compared with that of the control group (mean+/-SD 8.4+/-4.3 and 6.3+/-2.0 g m-2 h-1, respectively). There was a correlation between SC thickness and TEWL in control subjects but no correlation was found in patients with AD. The diffusivity of SLS through uninvolved AD skin was higher compared with normal skin (mean+/-SD 12.7+/-5.8x10(-9) and 6.2+/-3.0x10(-9) cm-2 h-1, respectively), while the partition coefficient between SC and water was lower (mean+/-SD 137+/-64 and 196+/-107, respectively). The results show a different penetration profile of SLS into the SC of patients with AD compared with control subjects. This indicates that even noninvolved skin in patients with AD has altered barrier characteristics, emphasizing the importance of skin protection and prevention of skin contact with chemicals.

Objective: Production sites of thromboxane and prostacyclin are compartmentalized within the human placenta. Thromboxane is produced primarily by the trophoblast cells closest to the maternal circulation, whereas prostacyclin is produced primarily by the endothelial cells closest to the fetal circulation. Theoretically, this arrangement allows for a selective inhibition of placental thromboxane by maternally derived aspirin because according to Fick's Second Law of Diffusion, the concentration of aspirin would decline as it crossed from the maternal to the fetal side, thereby sparing prostacyclin on the fetal side. We hypothesized that perfusion of aspirin on the maternal side of the placenta would result in inhibition of thromboxane with a sparing of prostacyclin.Study Design: To test this, we perfused human placental cotyledons in vitro with low doses of aspirin (5 × 10−-5 mom and 1 × 10−-4 mol/L) from the maternal side and measured the secretion rates of the stable metabolites of thromboxane and prostacyclin (TXB2 and 6–keto-PGF1α respectively). We also determined the transport of aspirin across the placenta.Results: Only 34% of the aspirin perfused on the maternal side crossed to the fetal side, providing proof of Fick's Second Law of Diffusion for the transport of aspirin across the human placenta. Compared to the control, perfusion of aspirin on the maternal side of the placenta preferentially inhibited the secretion of thromboxane while sparing prostacyclin. The total placental secretion rate of TXB2 was decreased by 48.8% by aspirin at a concentration of 5 × 10−-5 mom and by 80.2% at a concentration of 1 × 10−-4 mom. In contrast, the secretion rate of 6–keto-PGF1α was decreased by only 4.2% and 21.5% by these concentrations of aspirin. The placental secretion rate ratio of TXB, to 6–keto-PGF1α decreased from 14.9 for the control to 7.9 and 3.8 with each dose of aspirin, respectively. There were no changes over time in maternal or fetal secretion rates of thromboxane or prostacyclin for placental cotyledons perfused without aspirin.Conclusions: The compartmentalization of thromboxane and prostacyclin synthesis within the human placenta provides an arrangement whereby low doses of maternally derived aspirin can preferentially inhibit thromboxane because as aspirin crosses from the maternal to the fetal side, the higher concentrations of aspirin on the maternal side inhibit thromboxane in the trophoblast cells, but as aspirin crosses, its concentrations decline, so prostacyclin synthesis by the endothelial cells on the fetal side is spared. This is a beneficial effect of low-dose aspirin therapy for the prevention of preeclampsia.

Diffusion coefficients of organics in high density polyethylene (HDPE)

Tuna is one of the common fish consumed by Indonesian people. Tuna is highly perishable. Therefore, the handling technique is needed to maintain tuna’s quality. This research brought about the application of ozonated water in controlling quality of tuna by observing the effect of contact time, contact temperature and ozone dosage. The standard quality of tuna is detected from the number of aerobic mesophyll bacteria, pH value, water content and the protein content. The study was conducted by testing the ozone solubility in water and contacting tuna to ozonated water. Tuna was contacted to ozonated water for 40, 80, 120 minutes’ contact time at 8°C and ozone dosage of 0.3 mg/L; contacted at 37°C, 25°C and 8°C for 120 minutes and ozone dosage of 0.3 mg/L; and contacted at 8°C for 120 minutes with ozone dosage of 0.3 mg/L and 0.24 mg/L. After the treatment process, tuna was saved in 8°C chiller for 168 hours or seven days. The results show that the longer duration contact, the lower contact temperature, and the higher ozone dose, the lower the rate of quality degradation of tuna. Contacting tuna for 120 minutes can eliminate bacteria up to 66.7%, pH value decreases to 5.58 shortly after tuna was contacted to ozonated water; water content increases to 1.20% and protein decreases to 0.67% after 168 hours of storage. Contacting tuna at 8°C can eliminate bacteria up to 91.2%, pH value decreases to 5.48 shortly after tuna was contacted; water content increases to 1.14% and protein decreases to 0.22% after 168 hours. Meanwhile highest ozone dosage (0.3 mg/L) can eliminate bacteria up to 66.7%, pH value decreases to 5.58 after tuna was contacted; water content increases to 1.20% and protein decreases to 0.67% after 168 hours of storage.

Adsorption of heavy metal cationic ions (Cr, Pb, and Cu) onto coconut husk carbon (CHC) adsorbent has been studied using batch-adsorption method. The study was carried out to investigate the adsorption kinetic and adsorption isotherm of the coconut husk adsorbent for the removal of heavy metals in waste liquid effluent. The influence of pH, contact time, adsorbent dose, and adsorbent concentration, and temperature on the adsorption process was also studied. Results indicated an initial increase in adsorption rate, and optimal removal of heavy metal was reached within 70 minutes, further increase in contact time and temperature show significant change in equilibrium concentration. Also, further increase in adsorbent dosage revealed significant change in the sorption capacity of the CHC. The adsorption isotherms could be fitted well by both Langmuir and Freundlich models. The RI (equilibrium parameter) value in the present investigation was less than 1 (one) which indicates that the adsorption of the heavy metals ions on the CHC is favorable. The value of n for this study which indicates the degree of non-linearity between solution concentration and adsorption were 0.31–0.39, this result indicated that the adsorption of heavy metals onto the CHC is a chemical sorption. After treatment of synthetic heavy metal solution with the CHC, the adsorption isotherm model analysis revealed that the adsorption capacity (b) of CHC for the heavy metal were 89 mg/L (Cr), 125.5 mg/L (Pb), and 129.7 mg/L (Cu). Conclusively, the results indicate that the freely abundant agricultural waste-coconut husk can be treated for heavy metal adsorption but it’s not economically viable because it’s not renewable due to the chemisorption nature of the adsorption process.

In this paper, 60% ethanol was used as solvent to extract polyphenol from infructescence ofPlatycarya Strobilacea Sieb.et Zucc(IPSSZ), and the mass transfer kinetics of polyphenol at different temperature was investigated. According to Fick’s second law of diffusion, the kinetic equation forIPSSZ.extraction process was established with plate model, and the parameters, such asK(rate constant),Ea(activation energy) were gained. The results can provide the valuable theory basis for the technical design and further research of total polyphenol extraction process.

Convective drying characteristics of sludge from treatment plants in tomato processing industries

Surface chemical gradients were prepared on porous supports using a modified vapor deposition approach, and the shape and length of the gradient were controlled by restricting the diffusion layer. The gradients were formed on silica thin-layer chromatography (TLC) plates using organomonochlorosilanes of different sizes (C3, C4, C8, and phenyl) and visualized under UV radiation due to loss of fluorescence from the embedded fluorescent dye. Diffuse reflectance FT-IR chemically confirms the presence of C3 ligands. By constricting the diffusion of the silane vapor, the gradient shapes could be changed from concave to flat, and their lengths controlled. Photographs coupled with analysis using ImageJ were used to measure the saturation length of the gradient and the degree of curvature. C3 lengths covered 17.4-69.4% of the length of the TLC plate, and their curvature ranged from -1.9 to 11.9%, depending on the experimental conditions. Gradients formed by significantly restricting the diffusional profiles of the vapor yielded gradients with flat profiles, while those formed traditionally with no restriction of the vapor yielded gradients with an unusual concave shape due to the depletion of vapor in the center of the plate. By fitting the gradient profiles extracted from the photographs with Fick's second law of diffusion, diffusion coefficients (D) could be obtained. For the C3 silane, D was (0.8-2.2) × 10-3 cm2/s, depending on the specifics of the configuration used. As expected, smaller values of D were obtained for the larger molecular weight silanes (C3 > C4 > phenyl > C8). The lower molecular weight silanes gave rise to a higher degree of silane modification, whereas the larger ones gave rise to a lesser degree of silane modification. This work shows, for the first time, how to control the size and shape of surface chemical gradients on porous supports using a vapor phase diffusion method.

The design of a solar drier requires detailed information about drying kinetics of the products to be dried. The objective of our work is to characterize drying kinetics of tomato, okra, potato and mango and calculate the main drying parameters namely the drying rate, the moisture ratio and the effective diffusivity from the derivative form of the Fick’s second law of diffusion. We found that solar drying of tomato, okra, potato and mango occur in both constant and falling-rate phases. Sound experimental conditions and specifically continuous measurements and data collection during experiments, emerged as a major factor allowing the observation of both a constant-rate and falling-rate phases. Two models namely the Henderson & Pabis Model and the Page Model were used to characterize the evolution of moisture ratios <i>(MR)</i> over time. For each of the abovementioned crops, the Page Model appeared to give a better description of <i>MR</i> = <i>f(t)</i> with χ² varying from 0.0051 to 0.0978. As per the Effective Moisture Diffusivity, its values were 8.866×10^-09, 4.651×10^-09, 4.969×10^-09 and 5.177×10^-09 for mango, tomato, potato and okra respectively. Calculated drying constants were compared with the ones obtained by other authors in similar experimental conditions. The experimental dryer we used was a forced convective solar tunnel dryer. All experimentations were conducted in Niamey (Niger) from 7 to 9 June 2018, 3 to 4 Mars 2019, 24 to 26 April 2018 and 1 to 3 May 2018 for mango, tomato, potato and okra respectively.

abstractThe existing deterministic solution for prediction model of corrosion initiation cannot reflect input variable uncertainties very well. Thus there is a growing tendency for a stochastic model based on the probabilistic method to be developed and applied. This paper presents an approach to the fuzzy arithmetic based modeling of the chloride-induced corrosion of reinforcement in concrete structures that takes into account the uncertainties in the physical models of chloride penetration into concrete and corrosion of steel reinforcement, as well as the uncertainties in the governing parameters, including concrete diffusivity, concrete cover depth, surface chloride concentration and critical chloride level for corrosion initiation. There are a lot of models for predicting the onset time of reinforcement corrosion of structures exposed to corrosion environment. In this work, the RILEM model formula and Crank's solution of Fick's second law of diffusion are used. The parameters of the models are regarded as fuzzy numbers with proper membership function adapted to statistical data of the governing parameters, while the fuzziness of the corrosion time is determined by the fuzzy arithmetic of the interval arithmetic and extension principle. An analysis is implemented by comparing the deterministic calculation with fuzzy arithmetic for the above two prediction models.

A novel spectrophotometric method to measure the diffusion coefficient of aniline in benzene at 298.15 K

Theoretical and experimental approaches towards the determination of solute effective diffusivities in foods

Since the number of existing steel-reinforced concrete buildings affected by carbonation-induced corrosion is steadily increasing, there is a high demand for durable repair methods. Chemical re-alkalization (CRA) represents one such approach, relying on the transport of alkaline pore solution from a repair mortar into carbonated concrete. With the introduction of clinker-reduced binder systems such as hybrid alkali-activated binders (HAABs), their suitability for CRA and governing material parameters require further clarification. In this study, material-related chemical and structural influences on CRA were investigated using an adapted form of Fick’s second law of diffusion, incorporating a time-dependent attenuation factor, β(t). The CRA progression was evaluated over 28 days, distinguishing between an initial suction phase and a subsequent diffusion phase. The results show that a high initial alkalinity of the mortar pore solution (pH > 14) significantly enhances re-alkalization during the suction phase, reflected by suction factors a > 1. In contrast, progression during the diffusion phase is primarily governed by the potassium concentration gradient at the mortar–concrete interface, while structural parameters such as capillary porosity show no systematic correlation with the deceleration factor b (−0.46 ≤ b ≤ −0.26). The findings indicate that, within the investigated range, mortar pore solution chemistry has a stronger influence on CRA than structural properties, providing guidance for the targeted design of alkaline repair mortars.