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The proton‐exchange membrane is a crucial component of proton‐exchange membrane fuel cells (PEMFCs), and its mass transfer plays a vital role in the performance and energy conversion efficiency of fuel cells. In this article, the fundamental structure and working principle of PEMFCs, as well as the microstructure of the membrane, are introduced. The mass‐transfer mechanism of the membranes is systematically sorted out from the model of mass transfer and the corresponding simulation method, and the mass transfer is quantitatively calculated from the macroscopic perspective. Additionally, methods to improve the mass‐transfer efficiency from both internal and external aspects are discussed. In conclusion, in this article, mass transfer in PEMFCs is comprehensively discussed and a valuable reference is offered for future research and development in this field. [ABSTRACT FROM AUTHOR]

In 2022, China produced 1.018 billion tons of crude steel, with steel slag accounting for 10–15% of the output. The presence of 10–20% f‐CaO in steel slag causes volume instability, hindering comprehensive utilization. The generation of f‐CaO is closely associated with the dissolution of quicklime during the converter slag‐forming procedure. This study focuses on investigating the evolution of the lime–slag interface and the variations in lime dissolution rate under different slag conditions using the electron probe microanalyzer and ImageJ. The results reveal that the formation of the CaO–FeO solid solution, (Ca, Mg, Fe) olivine, and low‐melting point (Ca, Mg) olivine at 1400 °C. As the FeO content decreases, a dense and high‐melting‐point 2CaO·SiO2 layer is formed. A maximum thickness of the 2CaO·SiO2 layer is precipitated at a dissolution time of 180 s. Additionally, the average dissolution rate of lime in different slags shows an initial increase followed by a subsequent decrease. Among the slag studied, the highest average dissolution rate is in slag A3 at 2.24 × 10−6 m s−1, while the lowest rate is in slag A4 at 1.49 × 10−6 m s−1. The presence of the 2CaO·SiO2 layer hinders the mass transfer, thereby further inhibiting the reaction. [ABSTRACT FROM AUTHOR]

Li-O 2 batteries (LOBs) possess the highest theoretical gravimetric energy density among all types of secondary batteries, but they are still far from practical applications. The poor rate performance resulting from the slow mass transfer is one of the primary obstacles in LOBs. To solve this issue, a rotating cathode with periodic changes in the electrolyte layer thickness is designed, decoupling the maximum transfer rate of Li + and O 2 . During rotation, the thinner electrolyte layer on the cathode facilitates the O 2 transfer, and the thicker electrolyte layer enhances the Li + transfer. As a result, the rotating cathode enables the LOBs to undergo 58 cycles at 2.5 mA cm -2 and discharge stably even at a high current density of 7.5 mA cm -2 . Besides, it also makes the batteries exhibit a large discharge capacity of 6.8 mAh cm -2 , and the capacity decay is much slower with increasing current density. Notably, this rotating electrode holds great promise for utilization in other electrochemical cells involving gas-liquid-solid triple-phase interfaces, suggesting a viable approach to enhance the mass transfer in such systems., (© 2024 Wiley‐VCH GmbH.)

The chance of developing lung cancer is increased through being exposed to cigarette smoke illustrated by studies. It is vital to understand the development of particular histologic-type cancers regarding the deposition of carcinogenic particles, which are present in human airway. In this paper, the mass transfer and deposition of cigarette smoke, inside the human airway, are investigated applying the finite element method. The mass transfer and depositions of four types of critical cigarette smoke, namely 1, 3-butadiene, acrolein, acetaldehyde and carbon monoxide (CO), in a complete human-airway model (from mouth to B3 generation), under inhalation conditions, have been simulated. In this study, concentration distribution in inhalation is evaluated. The vapour deposition was modelled with 30 and 80 L.min-1 volumetric flow rates. Therefore, a two-dimensional model of human airway from the mouth to generation B3 was reconstructed. Then, for simulating the mass transfers and deposition fraction, the low-Reynolds-number (LRN) k–ω turbulence equation was used.

In front of the building energy issues and environmental impact bound, it appears that the earth envelopes are a promising track in terms of improving thermal comfort, indoor air quality, energy consumption and indoor humidity regulation. For this purpose, a characterization of hygrothermal transfers in the unfired earth was been conducted with experimental and numerical approaches. Thus, the studies at the material and wall scales were necessary to check dissociate and coupled hygrothermal behaviour. The material scale has been used to characterize properties related to heat and mass transfers. The hygrothermal coupling has been the subject of a specific study via a dual-climate test chamber at an earth wall scale. Finite Differences (FD) and Finite Elements (FE) implementations have resulted in a detailed analysis of transfers across the tested earth wall with a reduction work of order required to limit the calculation time. Emphasis is placed on the effects of moisture in the hygrothermal transfer in order to validate a digital tool developed in this work. [ABSTRACT FROM AUTHOR]

High levels of humidity in buildings lead to building pathologies. Moisture also has an impact on the indoor air quality and the hygrothermal comfort of the building’s occupants. To better assess these pathologies, it is necessary to take into account the heat and moisture transfer between the building envelope and its indoor ambience. In this work, coupled heat, air and moisture transfer model in multilayer walls (HAM) was established. Thereafter, the HAM model is coupled dynamically to a building behavior code (BES). The coupling concerns a co-simulation between COMSOL Multiphysics and TRNSYS softwares. Afterward, the HAM-BES co-simulation accuracy was verified by conducting an experimental validation using an experimental device devoted to assess the hygrothermal response of building walls under several hygrothermal conditions. The comparison between numerical and experimental results showed good agreement with acceptable errors margins. [ABSTRACT FROM AUTHOR]

SUMMARY A two-scales numerical analysis is set up in order to upscale the permeability of fractured materials such as concrete. To that aim, we couple finite element (FE) kinematics enhancements (strong discontinuities) representing fine scale cracks to the fine scale permeability tensor. The latter may be split into two parts: the first one is isotropic and corresponds to flows within the porosity of the material; the second one, based upon a set of cracks with different orientations and openings, is anisotropic. For the latter, each crack is a path for mass flow according to the Poiseuille law considering two infinite planes. We show how the upscaling procedure leads both to the definition of macroscopic permeability tensors as well as the flow rate evaluation for components of concrete structures. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Abstract: In foundry, induction furnace is a well-known, clean, energy-efficient and well-controllable melting process. In order to improve its refining capacity, a salty or oxide liquid layer can be added at the surface of the liquid metal. This paper aims to simulate numerically mass transfers that occur at the liquid–liquid interface between these two liquid layers. To achieve this, the flows in both salty and metallic phases are calculated, taking into account all the present phenomena in the bulks (i.e. electromagnetic stirring, buoyancy, turbulence, heat transfer), as well as those at the interface (i.e. electromagnetic shaping, viscous shear driving). Comparison is made with literature experimental measurements. [Copyright &y& Elsevier]

Abstract: A novel method of chitin hydrogel preparation, called vapor induced gelation, using exposure of chitin/N-methyl-pyrrolidone/LiCl solution to water vapors is presented. Compared to gelation induced by direct immersion in water, hydrogels are characterized by smaller deformation during gelation (area shrinkage is 20% instead of 65%), larger water volume fraction (75 instead of 62%, v/v) and 10 times higher apparent compression moduli. Their nanostructure consists of thicker and larger crystalline platelets network (thickness=37Å, apparent coherent crystalline size L 020 =145Å) comparatively to direct immersion gels (25Å and L 020 =95Å). Drug delivery potential of chitin hydrogels was determined for non-interactive low molecular molecules. [Copyright &y& Elsevier]

The formation of chitosan hydrogels using experimental and modeling approaches are described. Chitosan gelation was induced by an ammonia intake from a liquid phase (wet process) or a gaseous phase (vapor process), involving three steps: (i) external mass transfer at the interface, (ii) internal transport within the polymer solution, and (iii) chemical reactions inducing gelation. The experimental study allowed quantifying gelation fronts speeds from local measurement. The main resistance to gelation was investigated for both gelation processes. Experimental results exhibited that internal diffusion through the chitosan matrix was the main resistance in the whole gelation mechanism. The numerical model involved a coupling between mass and heat transfer phenomena and chemical reactions, in transient conditions. Numerical results were first validated and then used as a predictive tool to investigate (i) coupled mechanisms localized in the chitosan matrix and (ii) the influence of operating conditions on gelation rates. © 2011 American Institute of Chemical Engineers AIChE J, 2012 [ABSTRACT FROM AUTHOR]

The article presents a study that investigated the formation of chitosan-activated carbon composite hydrogels by vapor-induced phase separation process throughout the gelation with the use of inline gravimetric measurements. Results of the study revealed that the activated carbon particles used do not affect the gravimetric kinetics.The study showed that the ammonia partial pressure plays a part in gravimetric behaviors.

Abstract: The island of Taiwan is located on the convergent boundary between the Philippine Sea plate and the Chinese continental margin. It offers very active mountain building and collapsing processes well illustrated by the rugged topography, rapid uplift and denudation, young tectonic landforms, active faulting and numerous earthquakes. In this paper, using simple models, we have estimated vertical movements and associated absolute gravity variations which can be expected along a profile crossing the southern part of the island and probably suffering the highest rates of rising. The two different tectonic styles proposed for the island, thin-skinned and thick-skinned, were taken into account. Horizontal and vertical movements were modeled by an elastic deformation code. Gravity variations due to these deformations are then modeled at a second step. They are dominated by plate and free-air effects, i.e. elevation of the topography, with several μGalyr−1. By comparison, gravity changes generated by mass transfers are weak: maximum 0.1μGalyr−1 with the thin-skinned tectonic and 0.3μGalyr−1 with the thick-skinned tectonic. Though elastic rheology has limitations, this modeling offers interesting results on what gravity signal can be expected from the AGTO project (Absolute Gravity in the Taiwanese Orogen), which proposes to study the dynamic of these mountain ranges using absolute gravimetry (AG) and also including relative gravimetry (RG) and GPS measurements. [Copyright &y& Elsevier]

Abstract: Chitin membranes (3–5 wt.%) were prepared using immersion-gelation and vapor induced phase separation–gelation processes. The influence of the main physico-chemical parameters such as polymer concentration, pH, temperature, and coagulation bath composition on the area shrinkage and on the mass variation of the gel during chitin gelation has been studied. Results have shown that the key parameter was the mass transport phenomena between the polymer solution and the external environment. The slowing-down of the mass transfer kinetics, i.e. non-solvent penetration and solvent extraction, allows the formation of more homogenous gel morphology. [Copyright &y& Elsevier]

We describe amphibolite-facies shear zones affecting an orthogneiss from the Armorican Hercynian belt (Ile d’Yeu, western France). The deformation pattern is consistent with top-to-the-South thrusting followed by E–W extension, as documented elsewhere in the region. Shearing was accompanied by channelled fluid flow that transformed the orthogneiss into a peraluminous micaschist. Structural and mineralogical data indicate rather early strain localization. Then, temperature increase associated with crustal thickening favoured more distributed deformations marked by shear zone stretching and the development of a HT regional foliation. Chemical analyses made across five shear zones show mass transfers that mainly implied losses in Ca and Na, and gains in H2O, Mg, and K. Most results indicate constant volume transformation, but some suggest records of either gains or losses of volume (between +20% and −30%). This might reflect variable records of fluid-rock interactions according to the timing of initiation and subsequent evolution of individual shear zones, early thrusting stages being marked by up-temperature flow, and late thrusting stages by down-temperature flow. δ18O analyses suggest that fluids experienced significant isotopic exchange with orthogneisses. [ABSTRACT FROM AUTHOR]

Vacuum tumbling in a 1–5% lactic acid solution for a short time (1–10 min) improves the microbiological quality of deboned chicken legs, while inducing a light acidification and water absorption. The most significant variable of the process is the tumbling speed. High tumbling speeds lead to a high decontamination level of the chicken legs with regard to total viable counts and Enterobacteriaceae. Sodium lactate alone is unable to induce any decontamination at the same concentrations. Decontamination is probably more linked to acidification than to lactate ions. The use of vacuum tumbled (1 min in a 1% lactic acid solution) deboned chicken legs in the industrial manufacture of fresh chicken sausages led to a clear decrease in the number of Salmonella-positive batches. The incidence of positive batches was reduced threefold and the acid decontamination process did not adversely affect the sensory quality of the sausages. [ABSTRACT FROM AUTHOR]

Mass transfers triggered by a rare rainfall event on 20–21 July, 2004, with 58.4 mm of rain within 24 h and 71.7 mm of rain within 48 h in the Latnjavagge catchment (9 km2 , 950–1440 m a.s.l.; 68°20'N, 18°30'E) in the higher Abisko mountain region (Swedish Lapland), are quantified and analysed in direct comparison with mean annual mass transfers in this drainage basin. In years without rare rainfall events the Latnjavagge catchment is characterized by restricted sediment availability resulting in low mechanical denudation and mass transfers. During the rare rainfall event of 20–21 July, 2004, major stability thresholds on the slope systems (triggering debris flows and slides) and in the channel systems (break-up of channel debris pavements and step–pool systems) in the Latnjavagge catchment were passed and mass transfers by debris flows, slides and fluvial debris transport in creeks and channels were several times higher than the mean annual mass transfers in Latnjavagge. In the calculation of longer-term mass transfers and sediment budgets, rare events like the 20–21 July, 2004 rainfall event have to be considered as essential components. A reliable estimation of the recurrence intervals of such rare events is especially problematic. The general problem of defining an adequate length of process monitoring programmes is pointed out. [ABSTRACT FROM AUTHOR]

This work analyzes the electro-chemical phenomena that come up when surfaces of steel AISI-1010 contacts emulsions of the oil/water type. It was demonstrated that by using the disk-rotatory electrode (EDR) and the cell of incident submerged spout, in combination with techniques of potentio-dynamic polarization and spectroscopy of electro-chemical impedance, it is very much possible to correlate not only the intensity of the limit current, an eminent electro-chemical variable-answer that depends essentially on the transfer of mass, but also the intensity of corrosion, a variable that could be influenced by the phenomenon of mass transfer, with hydrodynamic variables; such as, the numbers of Reynolds and Schmidt and the phenomena of transfer of electric load. It was found that the mass transfer is important for the corrosion of steels in emulsions in conditions of sheeting regimen, coupling in these conditions to correlations of adimensional numbers inherent to the phenomena of mass and momentum transfer. [ABSTRACT FROM AUTHOR]