Diffusion Step Research Articles

Impacts of Surface Adsorption on Water Uptake within a Metal Organic Nanotube Material.

The confinement-dependent properties of solvents, particularly water, within nanoporous spaces impart unique physical and chemical behavior compared to those of the bulk. This has previously been demonstrated for a U(VI)-based metal organic nanotube that displays ice-like arrays of water molecules within the 1-D pore space and complete selectivity to H2O over all other solvents and isotopologues. Based upon our previous work on D2O and HTO adsorption processes, we suggested that the water uptake was controlled by a two-step process: (1) surface adsorption via hydrogen bonding to hydrophilic amine and carboxylic groups and (2) diffusion of the water into the hydrophobic 1-D nanochannels. The current study seeks to evaluate this hypothesis and expand our existing kinetic model for the water diffusion step to account for the initial surface adsorption process. Vapor sorption experiments, paired with thermogravimetric and Fourier-transform infrared analyses, yielded uptake data that were fit using a Langmuir model for the surface-adsorption step of the mechanism. The water adsorption curve was designated a type IV Brunauer-Emmett-Teller isotherm, which indicated that our original hypothesis was correct. Additional work with binary solvent systems enabled us to evaluate the uptake in a range of conditions and determine that the uptake is not controlled by the vapor pressure but is instead completely dependent on the relative humidity of the system.

Adsorption of naphthenic acids on peanut shell activated carbon: Batch and fixed-bed column study of the process

This study reports the adsorption of the naphthenic acids (NA) presents in an aviation kerosene (AVK) model mix using adsorbents prepared from peanut shell (PS). Both carbonization and the CO2 activation of the PS favored the adsorptive process. In the factorial design, the activated carbon prepared presented the highest adsorptive capacity for the lowest levels of the variables studied (<0.09 mm and without agitation). The adsorption equilibrium after 360 min, and the process is not only controlled by the intraparticle diffusion step. The adsorption isotherm was best fitted to Langmuir model with a maximum adsorbed amount of 884 mg g−1, whose heat of adsorption indicated that the process was of the physisorption. In the continuous adsorption study, it was verified that the increase of the flow and the concentration of NA decreased the rupture time. The breakthrough time and adsorptive capacity were reduced at each adsorption/desorption cycle. Given the shortage of works on this topic in literature, this study contributes with new findings that describe naphthenic acid adsorption in AVK.

Epoxy Functional Porous POSS Microparticle Synthesis

Epoxy-functional porous polyhedral oligomeric silsesquioxane (POSS) microparticles were synthesized by templated polymerization in two-steps by using monodisperse 2µm poly(GMA) seed latex particles as a template. In the first step, templated polymer latex was swollen in emulsion medium to obtain micron size porous POSS particles. In the second step, the hydrophobic monomers metharcyl-POSS, epoxy-functional monomer glycidyl methacrylate (GMA), the crosslinking agent GDMA and the thermal imitator diffused into the swollen template in emulsion medium for free-radical polymerization. The resultant poly(POSS-co-GDMA-co-GMA) microparticles were obtained in polydisperse form due to the high molecular weight of the silica cage core of POSS created difficulty in the diffusion step. However; monodisperse composite microparticles were obtained around 5.8 ± 0.4µm in size via centrifugal post-separation. The spherical fine porous hybrid structure was fully characterized as morphological, thermal, chemical composition, and crystalline form by SEM, TGA, FTIR, and XRD respectively.

Electrochemical Characterization of the Self-Assembled 4,4’-Bipyridine Layers at the Electrode | Ionic Liquid Interface

Self-assembled monolayers (SAMs) have significant importance in many modern applications1-2. The properties of SAMs depend on many aspects, such as the characteristics of individual molecules, forming the monolayer; by the interactions between these molecules; and SAM interactions with the electrolyte; the crystalline surface of the substrate; etc3. Therefore, the fundamental studies of these systems are crucial in determining the function of SAMs in various applications4-5.The aim of the current work was to study the adsorption characteristics of 4,4’- bipyridine from ionic liquid media at different electrodes6.Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements were conducted to characterize the electrochemical behavior of the self-assembled 4,4’-bipyridine (4,4’-BP) layers at the Sb(111) and Cd(0001) | 4,4’-BP+1-ethyl-3-methylimidazolium tetrafluoroborate (EMImBF4) interface. All the experiments were carried out in a three-electrode electrochemical cell in a glove-box, i.e., a nitrogen-controlled atmosphere.CV method was used to examine the electrochemical characteristics of the system under investigation within the potential region −0.9 V < E < 0.0 V for Sb(111) and −2.1 V < E < -0.8 V for Cd(0001) vs. Ag|AgCl. The current values increase rapidly at the more negative end of the studied potential region, indicating that reduction processes started at the Sb(111) and Cd(0001) | 4,4’-BP+EMImBF4 interface. In contrast with the data measured in EMImBF4, where the system shows ideal polarisable behaviour in the whole potential range. Interfacial capacitance (C s) values were calculated using the relation Cs=−(Z′′2\U0001d70bf)−1 . Capacitance values calculated depend on the composition of the electrolyte (i.e., on the concentration of 4,4’-BP), electrode material as well as on applied potential. Cs values are lower in the mixture than those measured in pure EMMImBF4 at a certain potential region in the case of both electrode materials. This effect is caused by the adsorption of 4,4’-BP molecules at the electrode surface. The shape of the phase angle vs. frequency (f) curves shows that mixed kinetic processes occur in the whole f range measured (i.e. diffusion and charge transfer steps in addition to adsorption).Acknowledgments:This work was supported by the Estonian Research Council grant PSG249, and by the EU through the European Regional Development Fund under project TK141 (2014-2020.4.01.15-0011).

Mathematical modeling of transport phenomena in compressible multicomponent flows

The present article proposes a diffuse interface model for compressible multicomponent flows with transport phenomena of mass, momentum and energy (i.e., mass diffusion, viscous dissipation and heat conduction). The model is reduced from the seven-equation Baer-Nuziato type model with asymptotic analysis in the limit of instantaneous mechanical relaxations. The main difference between the present model and the Kapila's five-equation model consists in that different time scales for pressure and velocity relaxations are assumed, the former being much smaller than the latter. Thanks to this assumption, the velocity disequilibrium is retained to model the mass diffusion process. Aided by the diffusion laws, the final model still formally consists of five equations. The proposed model satisfy two desirable properties: (1) it respects the laws of thermodynamics, (2) it is free of the spurious oscillation problem in the vicinity of the diffused interface zone. For solution of the model governing equations, we implement the fractional step method to split the model into five physical steps: the hydrodynamic step, the viscous step, the heat transfer step, the heat conduction step and the mass diffusion step. The split governing equations for the hydrodynamic step formally coincide with the Kapila's five-equation model and are solved with the Godunov finite volume method. The mass diffusion, viscous dissipation and heat conduction processes contribute parabolic partial differential equations that are solved with the Chebyshev method of local iterations. Numerical results show that the proposed model maintains pressure, velocity and temperature equilibrium near the diffused interface. Convergence tests demonstrate that the numerical methods achieve second order in space and time. The proposed model and numerical methods are applied to simulate the hydrodynamic instability problems in the inertial confinement fusion. Good agreement with experimental results is observed.

Design of Clothing with Encrypted Information of Lost Children Information Based on Chaotic System and DNA Theory

Abstract The encryption design is partly based on the fractional chaotic system and DNA theory. First, the dynamic characteristics of the newly proposed fractional Lü chaotic system are analyzed, and based on the analysis, a multi-image encryption algorithm is proposed. That is, the Arnold scrambling algorithm is used to scramble the image matrix, and then the DNA encryption theory is used to diffuse the image matrix. Among them, the scrambling step and the diffusion step are based on the chaotic sequence, and the encrypted image is finally obtained. Finally, the new encryption algorithm is evaluated, and the results show that the key space of the new encryption algorithm is further expanded and is very sensitive to key changes. The algorithm can effectively destroy the correlation of the original image, and can resist various cracking attacks. In summary, the multi-image encryption algorithm proposed in this paper has good encryption performance and provides a theoretical basis for practical applications. By reading those labels, children's identity and other relevant information can be acquired. This method may help police to obtain information on lost children and find their family rapidly.

Alginate-reinforced poly(3-hydroxybutyrate)/ poly(hydroxybutyrate-co-hydroxyvalerate) aerogel monoliths fabricated by phase separation as environmental floating adsorbents

Poly(3-hydroxybutyrate) (PHB)/poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) aerogel monoliths were prepared via nonsolvent induced phase separation and then sequentially immersed in ethanol and sodium alginate (ALG) solutions. The resulting composite aerogels contained up to a 52 wt% fraction ALG, causing a remarkable increase in their compressive modulus and collapse strength from 0.3 MPa and 33 kPa to 4 MPa and 406 kPa, respectively, i.e., by 13/12 times. An increase in the ALG contents in the composite aerogels allowed them to effectively adsorb both water and soybean oil, according to pseudo-second-order adsorption kinetics. The highly porous composite aerogel acted as an efficient floating adsorbent for a cationic dye (i.e., methylene blue (MB)) in water. MB adsorption was found to be strongly dependent on ALG contents in the adsorbent, as well as operating parameters such as the initial concentration, pH, and temperature of MB solutions. MB adsorption is best described by the Langmuir isotherm and follows pseudo-second-order kinetics. Ca2+-crosslinking of ALG further increased compressive strength but significantly decreased MB adsorption capability following pseudo-first-order kinetics, implying a slow internal diffusion step for MB adsorption due to its tightened network structure relative to noncrosslinked adsorbents.

Optimization, Nature, and Mechanism Investigations for the Adsorption of Ciprofloxacin and Malachite Green onto Carbon Nanoparticles Derived from Low-Cost Precursor via a Green Route.

The spread of organic pollutants in water spoils the environment, and among the best-known sorbents for removing organic compounds are carbonaceous materials. Sunflower seed waste (SFSW) was employed as a green and low-cost precursor to prepare carbon nanoparticles (CNPs) via pyrolysis, followed by a ball-milling process. The CNPs were treated with a nitric–sulfuric acid mixture (1:1) at 100 °C. The scanning electron microscopy (SEM) showed a particle size range of 38 to 45 nm, and the Brunauer–Emmett–Teller (BET) surface area was 162.9 m2 g−1. The elemental analysis was performed using energy-dispersive X-ray spectroscopy, and the functional groups on the CNPs were examined with Fourier transform infrared spectroscopy. Additionally, an X-ray diffractometer was employed to test the phase crystallinity of the prepared CNPs. The fabricated CNPs were used to adsorb ciprofloxacin (CFXN) and malachite green (MLG) from water. The experimentally obtained adsorption capacities for CFXN and MLG were 103.6 and 182.4 mg g−1, respectively. The kinetic investigation implied that the adsorption of both pollutants fitted the pseudo-first-order model, and the intraparticle diffusion step controlled the process. The equilibrium findings for CFXN and MLG sorption on the CNPs followed the Langmuir and the Fredulich isotherm models, respectively. It was concluded that both pollutants spontaneously adsorbed on the CNPs, with physisorption being the likely mechanism. Additionally, the FTIR analysis of the adsorbed CFXN showed the disappearance of some functional groups, suggesting a chemisorption contribution. The CNPs showed an excellent performance in removing CFXN and MLG from groundwater and seawater samples and possessed consistent efficiency during the recycle–reuse study. The application of CNPs to treat synthetically contaminated natural water samples indicated the complete remediation of polluted water using the ball-mill-fabricated CNPs.

Electrochemical Characterization of the Self-Assembled 4,4’-Bipyridine Layers at the Sb(111) | Ionic Liquid Interface

Self-assembled monolayers (SAMs) have significant importance in many modern applications1-2. The characteristics of SAMs depend on many aspects, like the characteristics of individual molecules, forming the monolayer; by the interactions between these molecules; and by SAM interactions with the electrolyte; the crystalline surface of the substrate; etc3. Therefore, the fundamental studies of these systems are crucial to determine the function of SAMs in various applications4-5.The aim of the current work was to study the adsorption characteristics of 4,4’- bipyridine from ionic liquid media and compare the results with previous data measured in aqueous electrolyte solutions.Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements were conducted to characterize the electrochemical behavior of the self-assembled 4,4’-bipyridine (4,4’-BP) layers at the Sb(111) | 4,4’-BP+1-ethyl-3-methylimidazolium tetrafluoroborate (EMImBF4) interface. All the experiments were carried out in a three-electrode electrochemical cell in a glove-box, i.e., nitrogen-controlled atmosphere.CV method was used to determine and to evaluate the electrochemical characteristics of the system under investigation within potential region, −0.9 V < E < 0.0 V vs. Ag|AgCl. The current values increase rapidly at E < −0.8 V, indicating that a reduction process started at the Sb(111) | 4,4’-BP+EMImBF4 interface. Thus, unlikely to the data measured in EMImBF4, where the system shows ideal polarisable behaviour in the whole potential range. Interfacial capacitance (C s) values were calculated using relation C s =−(Z′′2\U0001d70bf) −1 . Capacitance values calculated depend on the composition of the electrolyte (i.e., on the concentration of 4,4’-BP) as well as on the potential applied. C s values are lower in the mixture than those measured in pure EMImBF4 at E > – 0.7 V. This effect is caused by the adsorption and formation of the compact layer of 4,4’-BP molecules at the electrode surface. The C s vs. E dependences of the mixture increase significantly at E < −0.8 V (similarly to CV curves), which is not visible in the case of pure EMImBF4. This is also confirmed by small negative phase angle values at E < −0.8 V, where the shape of the phase angle vs. frequency (f) curves shows that mixed kinetic processes occurring in the whole f range measured (i.e. diffusion and charge transfer steps in addition to adsorption). At E > −0.8 V, phase angle values are close to − 80° for Sb(111)|4,4’-BP + EMImBF4 in a wide range of f. Only at low frequency values the mixed kinetic processes (adsorption, diffusion and partial charge transfer) were observed.The formation of ordered 4,4’-BP arrangements was most pronounced in the potential range −0.7 V < E < 0.0 V due to the reductive desorption of 4,4’BP at E < −0.8 V.Acknowledgments:This work was supported by the Estonian Research Council grant PSG249, and by the EU through the European Regional Development Fund under project TK141 (2014-2020.4.01.15-0011).

Removal and kinetics of cadmium and copper ion adsorption in aqueous solution by zeolite NaX synthesized from coal gangue.

Zeolite can remove the heavy metals in wastewater, but the removal efficiency was determined by the types of zeolites and the treatment conditions. In this study, a kind of zeolite NaX synthesized from the coal gangue, a by-product of coal production, was used and the removal efficiency of Cd2+ and Cu2+and the kinetic models were studied. The effects of its dosage, initial pH value of wastewater, and adsorption temperature on its adsorption of heavy metals Cd2+ and Cu2+ in the simulated wastewater were studied through the indoor experiments in laboratory, and the adsorption mechanism was analyzed by the adsorption kinetic model based on its adsorption efficiency and its structures. The results show that the zeolite NaX synthesized from coal gangue has a good adsorption effect on Cd2+ and Cu2+. The adsorption reaches the best effect when the dosage of zeolite is 2g/L, the initial pH of simulated wastewater is 5, the adsorption temperature is room temperature (25 ℃), and the removal efficiency of Cd2+ and Cu2+ (100mg/L) is more than 90%. Additionally, the Langmuir, Freundlich, and Temkin isothermal adsorption models were used to compare and analyze the adsorption effects. The equilibrium data was better fitted by the Langmuir model with the maximum adsorption capacities of 100.11mg/g (Cd2+) and 95.29mg/g (Cu2+), and both separation coefficients were 0-1, which shows that the process was the favorable adsorption. Weber Morris diffusion model shows that the adsorption process at 120min was more consistent with the pseudo-second-order kinetics model, and the adsorption efficiency was simultaneously controlled by the liquid diffusion step and intraparticle diffusion step. Moreover, the removal mechanism of Cd2+ and Cu2+ mainly includes physical adsorption and ion exchange. Therefore, the adsorption effect of zeolite synthesized from coal gangue is remarkable, which will provide a feasible and potential alternative for its resource application.

DiffSinger: Singing Voice Synthesis via Shallow Diffusion Mechanism

Singing voice synthesis (SVS) systems are built to synthesize high-quality and expressive singing voice, in which the acoustic model generates the acoustic features (e.g., mel-spectrogram) given a music score. Previous singing acoustic models adopt a simple loss (e.g., L1 and L2) or generative adversarial network (GAN) to reconstruct the acoustic features, while they suffer from over-smoothing and unstable training issues respectively, which hinder the naturalness of synthesized singing. In this work, we propose DiffSinger, an acoustic model for SVS based on the diffusion probabilistic model. DiffSinger is a parameterized Markov chain that iteratively converts the noise into mel-spectrogram conditioned on the music score. By implicitly optimizing variational bound, DiffSinger can be stably trained and generate realistic outputs. To further improve the voice quality and speed up inference, we introduce a shallow diffusion mechanism to make better use of the prior knowledge learned by the simple loss. Specifically, DiffSinger starts generation at a shallow step smaller than the total number of diffusion steps, according to the intersection of the diffusion trajectories of the ground-truth mel-spectrogram and the one predicted by a simple mel-spectrogram decoder. Besides, we propose boundary prediction methods to locate the intersection and determine the shallow step adaptively. The evaluations conducted on a Chinese singing dataset demonstrate that DiffSinger outperforms state-of-the-art SVS work. Extensional experiments also prove the generalization of our methods on text-to-speech task (DiffSpeech). Audio samples: https://diffsinger.github.io. Codes: https://github.com/MoonInTheRiver/DiffSinger.

A phase-change model for diffusion-driven mass transfer problems in incompressible two-phase flows

We present a VOF-based numerical method for incompressible Direct Navier–Stokes (DNS) equations for diffusion-driven phase-change flows. A special emphasis is placed on the treatment of velocity discontinuities across the interface. A novel algorithm is presented to smoothly extend the liquid velocity field across the interface in a way that the interface can be transported by a divergence-free velocity field. The transport of species is treated with a two-scalar approach and special attention is paid to the advection and diffusion steps in order to prevent artificial mass transfer. The methodology is implemented in the open-source code Basilisk and is validated against analytical and semi-analytical models. The relative errors on the relevant quantities are generally below 1% for the finest grids. The method is finally applied to study the growth of electrochemically generated bubbles on planar electrodes and the effect of contact angles and number of nucleation sites is investigated.

Evaluation of the Immobilization of Coexisting Heavy Metal Ions of Pb2+, Cd2+ , and Zn2+ from Water by Dairy Manure-Derived Biochar: Performance and Reusability.

Heavy metals including Cd, Pb, and Zn are prevalent stormwater and groundwater contaminants derived from natural and human activities, and there is a lack of cost-effective treatment for their removal. Recently, biochar has been increasingly recognized as a promising low-cost sorbent that can be used to remediate heavy metal contaminated water. This study evaluates the immobilization/release performance of dairy manure-derived biochar (DM-BC) as a sustainable material for competitive removal of coexisting heavy metal ions from water and explains the underlying mechanism for regeneration/reusability of biochar. Results showed that the metal ions exhibited competitive removal in the order of Pb2+ ≫ Zn2+ > Cd2+. The pH played a decisive role in influencing metal ion speciation affecting the electrostatic attraction/repulsion and surface complexation. Higher pH led to greater removal for Pb2+ and Cd2+, whereas Zn2+ showed maximum removal at pH ≈ 7.5. Diffuse reflectance infrared spectroscopy, scanning electron microscopy, and X-ray diffraction confirmed the interactions and precipitation reactions of oxygen-containing functional groups (e.g., ─OH, , and Si─O) as key participants in metal immobilization. Langmuir, Freundlich, and Redlich-Peterson isotherm modeling data showed varied and unique results depending on the metal ion and concentration. The removal kinetics and model fitting showed that the three steps of intraparticle diffusion might be more representative for describing the immobilization processes of metal ions on the external surface and internal pores. In the flow-through columns, DM-BC effectively retained the mixed metal ions of Cd2+, Pb2+, and Zn2+ showing 100% removal for the duration of the column run over three cycles of regeneration and reuse.

Real-time changes in the AC magnetic susceptibility of reagents during immunomagnetic reduction assays

Antibody-functionalized magnetic nanoparticles dispersed in phosphate-buffered saline solution were used as reagents in immunomagnetic reduction assays. Biomolecules are detected in bioliquid samples when they associate with magnetic nanoparticles and reduce the AC magnetic susceptibility χac of the reagent at a given frequency. In this study, the chemical kinetics for the real-time χac during the association was investigated. The association kinetics between biomolecules and nanoparticles consists of diffusion and binding steps. It was found that the diffusion speeds up in samples with higher concentrations of molecules. Furthermore, the period of association was longer for samples having higher concentrations of molecules. The association rates were proportional to the T-Tau concentration. The results showed that one biomolecule was associated with one magnetic nanoparticle.

Kinetics and isotherm studies for the adsorption of boron from water using titanium dioxide

AbstractBoron is a necessary element for plants that are generally found in the ground and seawater, but it can also be poisonous in large doses. Contamination of water with boric acid or borate ions is a global concern. Due to the absence of the chemical charge that boron possesses, its removal is often difficult. To investigate boron's adsorption characteristics, kinetic, isotherm, and isothermal studies were performed. The adsorption of boron was shown to be a pH‐dependent mechanism, with the best results at around pH 9.0. About 47% of the boron from a solution of 50 mg L−1 was removed using 5 g titanium dioxide in 30 min. It was also demonstrated that boron adsorption kinetics increased with temperature, which is best described by the pseudo‐second‐order kinetic model (R2 &gt; 0.98) and also fits well with Elovich and pseudo‐first‐order models (R2 &gt; 0.94) at pH 9.0. Equilibrium was reached in about 40 min for all the samples. The film boundary layer diffusion step limits the rate. Experimental results correspond well to the Freundlich isotherm (R2 = 0.95–0.99). Langmuir and Temkin's isotherms also fitted reasonably well (R2 = 0.94–0.98). The Freundlich and Langmuir constants indicate favourable adsorption. The Gibbs free energy (ΔG) values increased negatively (from −11.47 to −15.63 kJ mol−1) with increasing temperature, signifying a feasible and spontaneous process. The enthalpy change (ΔH) value of about 30.35 kJ mol−1 indicated endothermic physical adsorption. The results indicate that titanium dioxide is an excellent and safe adsorbent for the removal of boron from water.

A novel multi-resolution technique for solving complex vorticity patterns in planar viscous flows past bodies through the DVH method

The Diffused Vortex Hydrodynamics (DVH) is a Vortex Particle Method widely validated in the last decade. This numerical approach allows cost-effective simulations of viscous flows past bodies at moderate and high Reynolds numbers, by taking into account only the rotational part of the flow field. In the present work a novel multi-resolution technique is presented in order to limit the number of particles in the computational domain, further improving the solver efficiency. The proposed technique preserves the total circulation and uses the (Benson et al., 1989) deterministic algorithm to regularize the particle spatial distribution during the diffusion step. Simulations of the planar flow past five cylindrical sections at Re=10,000 are discussed: flat plate, triangle, square, circular cylinder and a symmetrical airfoil. Although the simulations are carried out in a two-dimensional framework, complex vorticity patterns develop because of the flow separation and the Reynolds number considered. Comparisons with a Finite Volume solver are carried out and discussed, such highlighting the advantages of the present numerical approach.

Smart Sustainable Cities—Case Study Südwestfalen Germany

The transformation of society into sustainable structures is one of the most important tasks for the future. That cities have a decisive role to play in this transformation process has been known at least since Rio 1992. They have enormous pressure to act for change: They are at the same time problem and solution for sustainable development. Currently there is another significant development for cities—the need and external pressure to be “smart”, often understood merely as applying the latest digital technologies to become more efficient. The Smart City and the Sustainable City can work hand in hand or hinder each other, depending on their interpretation. In this study we focus on five Smart Cities in Western Germany to get a closer look at how they shape their processes and whether the underlying motivation is to become a technologically Smart City, focus on sustainable development, or both. With the help of the innovation biography research method, we show how cities shape the dynamic process towards forming a Smart City, the role sustainable urban development plays in the process, who the actors involved are, and the important role improved knowledge management then plays for the diffusion of the Smart Sustainable City within the region. It becomes clear how important communication and narratives are both in the process within each City towards forming a Smart Sustainable City and for the first step of diffusion, the adaptation of other cities within the region. This study is intended to serve both as a basis for cross-regional consideration and dialogue for the transfer of successful processes.

Radio-frequency magnetron sputtered thin-film La0.5Sr0.5Co0.95Nb0.05O3-δ perovskite electrodes for intermediate temperature symmetric solid oxide fuel cell (IT-SSOFC)

The present work explores the application of La0.5Sr0.5Co0.95Nb0.05O3-δ (LSCNO) perovskite as electrode material for the symmetric solid oxide fuel cell. Symmetric solid oxide fuel cells of thin-film LSCNO electrodes were prepared to study the oxygen reduction reaction at intermediate temperature. The Rietveld refinement of synthesized material shows a hexagonal structure with the R-3c space group of the prepared perovskite material. Lattice parameter and fractional coordinates were utilized to calculate the oxygen ion diffusion coefficient for molecular dynamic simulation. At 973 K, the oxygen ion diffusion of LSCNO was 1.407 × 10−8 cm2 s−1 higher by order of one magnitude than that of the La0.5Sr0.5CoO3-δ (7.751 × 10−9 cm2 s−1). The results suggest that the Nb doping provide the structural stability which improves oxygen anion diffusion. The enhanced structural stability was analysed by the thermal expansion coefficient calculated experimentally and from molecular dynamics simulations. Furthermore, the density functional theory calculation revealed the role of Nb dopant for oxygen vacancy formation energy at Sr–O and La–O planes is lower than the undoped structure. To understand the rate-limiting process for sluggish oxygen diffusion kinetics, 80 nm and 40 nm thin films were fabricated using radio frequency magnetron sputtering on gadolinium doped ceria electrolyte substrate. The impedance was observed to increase with an increasing thickness, suggesting the bulk diffusion as a rate-limiting step for oxygen ion diffusion. The electrochemical performance was analysed for the thin-film symmetric solid oxide fuel cell, which achieved a peak power density of 390 mW cm−2 at 1.02 V in the presence of H2 fuel on the anode side and air on the cathode side.

Implementation of tissue clearing and 3‐dimensional volumetric imaging approaches for visualization of anatomical structures in autonomic nuclei

Alterations within central nervous system (CNS) autonomic nuclei contribute to a wide array of diseases. In this context, significant advancements have been made into disease‐related molecular mechanisms in autonomic brain regions. While helpful, it is important to consider that information processing within the CNS occurs through dynamic micro‐architectural structural interactions, such astrocyte‐neuron synaptic connections. However the traditional method for evaluating CNS morphology and synaptic contacts between cells is performed with immunohistochemistry on thin brain sections. An inherent limitation of this approach is not only the narrow 2‐dimensional field of view, but also the lack of optical transparency that minimizes high‐resolution imaging of anatomical structures and cell‐cell interactions. To overcome these limitations, here we sought to optimize tissue clearing approaches combined with 3D volumetric imaging for autonomic CNS nuclei. We focused our initial efforts on the forebrain subfornical organ (SFO), a region lacking a blood‐brain‐barrier, given: 1 Alterations in the SFO have been described to contribute to numerous disease conditions; and 2 The SFO represents a unique technical challenge for 3D imaging due to the complexity of cellular processes and surrounding lateral ventricle space. As a first step, we used a “passive” CLARITY tissue approach in 8‐week‐old C57Bl/6J male mice. Mice were transcardially perfused with an acrylamide‐based hydrogel in standard fixative. Subsequently, a brain section encompassing the entire SFO (~1mm) was obtained, and a series of thermal diffusion steps was performed to place existing protein structures in a “scaffold” and remove the lipid contents ‐ rendering the tissue transparent. Whole‐mount immunohistochemistry for astrocytes was then conducted using GFAP and DAPI as a nuclei marker, followed by 3D volumetric multiphoton imaging to acquire high‐resolution visualization of the entire SFO in three planes (Figure top). In brief, this approach proved to be a significant advancement beyond standard 2D histology, and 3D visualization of intricate astrocyte processes throughout the whole SFO was possible. However, a major limitation was the extensive amount of time required to process a single sample; 2 weeks for tissue clearing and 2 weeks for primary and secondary antibody incubation. Based on this, we adapted our protocol to an “active” CLARITY approach and employed electrophoretic‐based clearing of large brain sections (n=5), which resulted in a reduction in clearing time from 2 weeks to 4 hours. It was also readily apparent that this approach rendered the tissue more transparent than passive clearing, allowing for greater visualization of astrocyte processes (Figure middle). Preliminary analysis with IMARIS software to analyze astrocyte surface area and dendritic processing (Figure bottom) revealed highly complex SFO astrocytic structures with some dendrites extending from soma at the lateral ventricle throughout and surrounding nearly the entire SFO; these processes are not visualized with standard histology. Collectively, these approaches highlight the utility of tissue‐based clearing for 3D visualization of anatomical structures within autonomic nuclei and provide a framework to understand structure‐function relationships within these brain regions in the regulation of physiological and pathophysiological conditions.

Humic acid and nano-zeolite NaX as low cost and eco-friendly adsorbents for removal of Pb (II) and Cd (II) from water: characterization, kinetics, isotherms and thermodynamic studies

Humic acid as a green-sorbent was synthesized from marine sediments. While kaolin was modified to nano-zeolite NaX. Different tools such as FT-IR, SEM, EDX and XRD were applied to confirm the characteristics of the generated green-sorbents. Different factors such as pH, contact time, sorbent dosage, initial metal ion concentration, temperature and interfering ions were carefully examined and used to optimize the batch adsorption process for Cd2+ and Pb2+. A small dose of nano-zeolite of 100 mg was required to attain the maximum adsorption of Pb2+ at pH about 7, shacking time at 60 min and Pb2+ concentration at 30 ppm. Also, the maximum sorption capacity of Cd2+ ions on nano-zeolite was achieved in a neutral medium and very short contact time implying the economic feasibility of the adsorption process. In the case of humic acid, the maximum removal capacity for Pb2+ and Cd2+ was operated at acidic medium and shacking time was 40 min. Metal ions remediation results were evaluated by some adsorption isotherm models at different temperatures. The kinetic and thermodynamic variables were also computed. The data fitted very well with the linear Langmuir and the pseudo-second-order model implying a favourable adsorption process. The sorption of Cd2+ and Pb2+ was regulated by both external mass transfer and intraparticle diffusion steps over the whole range of concentrations, as shown by the results. The metal ions removal percentage from four real water samples by green sorbents were applied and provides good evidence of two sorbents as promising eco-sorbent for removal of heavy metal ions.