Exchange Diffusion Research Articles

Novel ionic liquid-infused PVA-based anion exchange membranes boosting bioelectricity yield from microbial fuel cells.

The goal of this research is to develop and characterize low-cost NH4I doped polyvinyl alcohol (PVA)-4-ethyl-4-methylmorpholiniumbromide (ionic liquid) anion exchange membranes (AEM) and its application for membrane cathode assembly. Physical characterization like FTIR, POM, and XRD notified the functional groups, basic structure, and amorphosity of the produced membrane, and it was employed in single-chambered microbial fuel cells (sMFCs) as a separator. The membranes in terms of oxygen diffusion, proton conductivity, and ion exchange capabilities were evaluated. PVA-ionic liquid composite membrane had a greater volumetric power density (PD) with a rise in the ionic liquid concentration, owing to lower internal resistance and reduced biofouling. Ionic conductivity also reduces as loading increases over a certain level of concentration. The incorporation of ionic liquid into the membrane had a considerable impact on impedance minimization (an enhancement in anionic conductivity) and biofouling. When MFC was used with a PVA-ionic liquid-based membrane cathode assembly (MCA), the highest PD of 7.98W/m3 was attained which is better than other composite membranes. The MCA surface area boosted the power output. The PVA-ionic liquid composite membrane proved to be a viable alternative to the more costly commercially available MFC membrane. This paper's novelty lies in synthesizing ammonium iodide (NH4I) doped PVA-ionic liquid membrane and further utilizing it as a separator in MFC. Also, this study demonstrates the membrane's potential for enhancing MFC performance, establishing it as a viable alternative to expensive commercial membranes.

Impact of Li+ Ion Diffusion Coefficient and Grain Size of Active Material on Overpotential

Introduction The charge–discharge reaction focusing on the lithium insertion material has two steps: (1) the charge transfer process and (2) the ion diffusion process within the particle. The Butler–Volmer equation is valid when ion diffusion is sufficiently fast and charge transfer is dominant. However, when ion diffusion dominates, the Butler–Volmer equation is inapplicable. Nevertheless, the effect of ion diffusion in active material particles is not well understood.We investigated the effect of the active material diffusion coefficient on the electrochemical response, particularly the overpotential, using Battery Design StudioⓇ (BDS), a one-dimensional lithium-ion battery performance simulator using the Newman model, to create a single-particle measurement model with the exchange current density and diffusion coefficient as parameters.[1] In this paper, we discuss the effect of the active material particle size, in addition to the active material exchange current density and diffusion coefficient, on the electrochemical response by simulating pulse application tests and generating Tafel plots. Experimental A single-particle measurement model with the area, thickness, porosity, and specific surface area reproducing spherical LiCoO2 inside a cubic working electrode was set up in the BDS. A flat Li metal electrode was used as the counter electrode. To minimize the overpotential, the parameters of the counter electrode and electrolyte were set significantly higher than their actual values.We experimented with combinations of three different exchange current densities (1 × 10−4, 1 × 10−3, and 1 × 10−2 A cm− 2), eight different diffusion coefficients (1 × 10−5, 1 × 10−6, 1 × 10−7, 1 × 10−8, 1 × 10−9, 1 × 10−10, 1 × 10−11, and 1 × 10−12 cm2 s−1), and three different diameters (1, 10, and 100 μm) for LiCoO2. The Tafel plots were obtained using the overpotential from the simulated pulse application at 50% state of charge. The setup model is described in detail in our previous study [1]. Results and discussion Fig. 1 shows the Tafel plots for different grain sizes and the same parameters (exchange current density = 1 × 10−3 A cm−2, different diffusion coefficient = 1 × 10−9 cm2 s−1). When the current density is not excessively small, the aforementioned parameters demonstrate a linear relationship between the current density (log i) and the overpotential (η), indicating a Tafel region lying on the dashed straight line. This indicates that charge transfer is dominant. As the current density (log i) increases, the overpotential (η) deviates from the dashed line, the gap of which is attributed to the effect of ion diffusion. Compared to the 1 and 100 μm grain sizes, the shape of the Tafel plots is different, although the parameters (exchange current density and diffusion coefficient) are the same except for the grain size. The plots for the 100 µm grain size fall out of the Tafel region at the current density (log i) of -2.2 or higher, which is earlier than those for the 1 µm grain size. In other words, a larger grain size causes the diffusion coefficient to become dominant at lower current densities. In the presentation, we discuss the real parameters of LiCoO2. Acknowledgement This study was partially funded by JSPS KAKENHI under Grant Numbers JP20K14729 and JP23K13327. Reference [1] K. Ando, et al. Journal of Electroanalytical Chemistry, 948 (2023) 117802. Figure 1

Fabrication and Characterizations of Microwave‐Assisted Gelatin Cross‐Linked LBG/Guar Gum–Based Super Porous Hydrogels With Metformin Hydrochloride for Open Incision Wound Healing

ABSTRACTThe goal of this study was to fabricate gelatin cross‐linked Locust bean gum (LBG)/guar gum–based hydrogels with microwave assistance for diabetic wound healing applications and evaluate it for physicochemical properties. In the last few years, microwave irradiation has gained acceptance as a reliable technique for quickening and streamlining chemically modified reactions. In order to achieve this, metformin‐loaded LBG and guar gum–based hydrogel were formulated employing microwave radiation. Moreover, the microwave‐assisted–based metformin hydrogel are microwave‐assisted reaction sudden increase in temperature may led to distortion of molecules, very vigorous and which may be hazardous, but environmental sustainability and friendly chemistry concepts are supported by microwave irradiation. The optimized formulation (F3) showed significantly improved physicochemical properties, with a swelling capacity of 480.4% ± 2.5%. The results indicate an appropriate duration for adequate drugs diffusion and nutrition exchange. Controlled disintegrate and sustained release of embedded drug molecules from F3 may have an impact on antibacterial activity. The study indicated that microwave‐assisted polymer blend hydrogels had adequately improved physical qualities, making them a promising candidate for improving diabetic wound healing and hastening skin tissue regeneration.

Engineering a novel interface structure on La0.75Sr0.25Cr0.5Mn0.5O3-δ-Gd0.1Ce0.9O2-δ fuel electrode with excellent electrochemical performance and sulfur tolerance for electrocatalytic CO2 reduction

Surface and interface engineering as an efficient and controllable strategy in designing electrode structure has been widely investigated for achieving high catalyst activity and durability of robust electrodes in solid oxide cells (SOCs). The constructed heterojunction structures favor expedited charge transfer and promote the catalytic reaction. Anti-coking La0.75Sr0.25Cr0.5Mn0.5O3-δ (LSCM)-based fuel electrodes are considered as promising candidates for alternative Ni-based cermet electrodes in solid oxide electrolysis cell (SOEC), however, they suffer from insufficient electrocatalytic activity for CO2 electrolysis. Herein, Mn-containing Pr0.6Sr0.4FeO3-δ (Pr0.6Sr0.4Fe0.8Mn0.2O3-δ, PSFM) nanoparticles with excellent catalyst activity are synthesized and epitaxially grown on the surface of LSCM via infiltration technique. The spontaneous connected interface can provide direct tunnel for oxygen ion and electron transport along the (110) plane of LSCM. Meanwhile, this interface promotes an increase in oxygen vacancies and enhances both surface oxygen exchange and bulk oxygen diffusion capacities. These improvements are advantageous for CO2 adsorption and carbonate dissociation at three phase boundaries (TPBs), leading to a significant enhancement in the kinetics of CO2 reduction reaction. The electrolyte-supported single with PSFM/La0.75Sr0.25Cr0.5Mn0.5O3-δ-Gd0.1Ce0.9O2-δ (LSCM-GDC) fuel electrode exhibits an impressive current density of 1.09 A cm−2 at the applied voltage of 1.5 V and 800 °C, which increases by approximately 336 % than that of LSCM-GDC. In addition, the atomic arrangement enables in-situ formation of PSFM by trapping of surface Sr/Mn atoms on the LSCM surface, avoiding Sr segregation and enhancing the resistance to sulfur poisoning. This study demonstrates a strategy for achieving the enhanced CO2 electrolysis performance and sulfur tolerance by engineering highly active interface.

KMT5C leverages disorder to optimize cooperation with HP1 for heterochromatin retention

A defining feature of constitutive heterochromatin compartments is the heterochromatin protein-1 (HP1) family, whose members display fast internal mobility and rapid exchange with the surrounding nucleoplasm. Here, we describe a paradoxical state for the lysine methyltransferase KMT5C characterized by rapid internal diffusion but minimal nucleoplasmic exchange. This retentive behavior is conferred by sparse sequence features that constitute two modules tethered by an intrinsically disordered linker. While both modules harbor variant HP1 interaction motifs, the first comprises adjacent sequences that increase affinity using avidity. The second motif increases HP1 effective concentration to further enhance affinity in a context-dependent manner, which is evident using distinct heterochromatin recruitment strategies and heterologous linkers with defined conformational ensembles. Despite the linker sequence being highly divergent, it is under evolutionary constraint for functional length, suggesting conformational buffering can support cooperativity between modules across distant orthologs. Overall, we show that KMT5C has evolved a robust tethering strategy that uses minimal sequence determinants to harness highly dynamic HP1 proteins for retention within heterochromatin compartments.

Boundary Layer Modelling of Flow Acceleration and Energy Transfer Effects in Smart Pavement Design

The integration of remote technology into the construction industry has advanced the emergence of smart, self-learning infrastructure across all levels of land transportation design and development. However, energy harvesting capabilities for smart road ventilation purposes have not yet been fully researched as the world gravitates towards energy sustainability. This study thus presents a mathematical investigation of the self-draining design potentials of road pavements, leveraging on energy absorption and conversion to accelerate conductive and convective ventilation of these pavements during wet conditions, as a means of ensuring the skid resistance and safety of such pavements are not compromised. Applying numerical methods with the aid of commercial software code MATLAB®, the classical physics of fluid-surface interaction was used to model accelerated drainage of microflood off paved surfaces through methodical modification of the thickness of the boundary layer associated with the flow regime over the flat road surface. Results indicate significant influences of energy exchange, thermal, and viscous diffusivity on flow acceleration. Alterations in parameters such as the slip factor, thermally induced Brownian motion or phoretic characteristics of the fluid particles at the boundary induce accelerated flow at the surface of the pavement. The findings contribute to the advancement of smart infrastructure by offering practical insights into the potential benefits of integrating energy-harvesting technologies into road pavement systems. By optimizing flow acceleration mechanisms, smart pavements can play a crucial role in improving road safety and sustainability in urban environments.

Multiphase flow and reactive transport benchmark for radioactive waste disposal

Compacted bentonite is part of the multi-barrier system of radioactive waste repositories. The assessment of the long-term performance of the barrier requires using reactive transport models. Here we present a multiphase flow and reactive transport benchmark for radioactive waste disposal. The numerical model deals with a 1D column of unsaturated bentonite through which water, dry air and CO2(g)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\hbox {CO}_{2{(g)}}}$$\\end{document} may flow and with the following reactions; aqueous complexation, calcite and gypsum dissolution/precipitation, cation exchange and gas dissolution. INVERSE-FADES-CORE V2, DuMuX\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {DuMu}^X$$\\end{document}, TOUGHREACT and iCP were benchmarked with 6 test cases of increasing complexity, starting with conservative tracer transport under variably unsaturated conditions and ending with water flow, gas diffusion, minerals and cation exchange. The solutions of all codes exhibit similar trends. Small discrepancies are found in conservative tracer transport due to differences in hydrodynamic dispersion. Computed CO2(g)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\hbox {CO}_{2{(g)}}}$$\\end{document} pressures agree when a sufficiently refined grid is used. Small discrepancies in CO2(g)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\hbox {CO}_{2{(g)}}}$$\\end{document} and pH are found near the no-flow boundary at early times which vanish later. Discrepancies are due differences in the formulations used for gas flow at nearly water-saturated conditions. Computed CO2(g)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\hbox {CO}_{2{(g)}}}$$\\end{document} pressures show a fluctuation between 10-4\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$10^{-4}$$\\end{document} and 10-3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$10^{-3}$$\\end{document} years which slows down the in-diffusion of CO2(g)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\hbox {CO}_{2{(g)}}}$$\\end{document}. This fluctuation is associated with chemical reactions involving CO2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\hbox {CO}_{2}}$$\\end{document}. There are discrepancies in solute concentrations due to differences in the Debye–Hückel (DH) formulation. They are overcome when all codes use the same DH formulation. The results of this benchmark will contribute to increase the confidence on multiphase reactive transport models for radioactive waste disposal.

129Xe Image Processing Pipeline: An open-source, graphical user interface application for the analysis of hyperpolarized 129Xe MRI.

Hyperpolarized 129Xe MRI presents opportunities to assess regional pulmonary microstructure and function. Ongoing advancements in hardware, sequences, and image processing have helped it become increasingly adopted for both research and clinical use. As the number of applications and users increase, standardization becomes crucial. To that end, this study developed an executable, open-source 129Xe image processing pipeline (XIPline) to provide a user-friendly, graphical user interface-based analysis pipeline to analyze and visualize 129Xe MR data, including scanner calibration, ventilation, diffusion-weighted, and gas exchange images. The customizable XIPline is designed in MATLAB to analyze data from all three major scanner platforms. Calibration data is processed to calculate optimal flip angle and determine129Xe frequency offset. Data processing includes loading, reconstructing, registering, segmenting, and post-processing images. Ventilation analysis incorporates three common algorithms to calculate ventilation defect percentage and novel techniques to assess defect distribution and ventilation texture. Diffusion analysis features ADC mapping, modified linear binning to account for ADC age-dependence, and common diffusion morphometry methods. Gas exchange processing uses a generalized linear binning for data acquired using 1-point Dixon imaging. The XIPline workflow is demonstrated using analysis from representative calibration, ventilation, diffusion, and gas exchange data. The application will reduce redundant effort when implementing new techniques across research sites by providing an open-source framework for developers. In its current form, it offers a robust and adaptable platform for 129Xe MRI analysis to ensure methodological consistency, transparency, and support for collaborative research across multiple sites and MRI manufacturers.

Waste glass as a source for green synthesis of mesoporous adsorbent for efficient removal of heavy metals

Mesoporous analcime Adsorbent (MaA) was cogently synthesized in a hydrothermal reaction where a waste silica glass powder was mixed into NaOH solution. The satisfactory reaction properties were achieved by regulating the conditioning time (Ct), reaction temperature (Rt), and relative ratio of the reactants (Rr = SiO2:Na2O). XRF, XRD, SEM, BET, FTIR, AFM, TG and TEM analysis formed part of the selected samples. The prepared MaA adsorbent was then applied to treat Pb2+, Cd2+ and Cu2+ ions, thus effectively allowing the physicochemical properties (pH, temperature and contact duration), on the adsorption amount to be examined. Upon completion, the results indicated that the initial pH as well as the contact duration had notable effect on the adsorption amount. Conversely, the temperature change had an insignificant effect on the equilibrium adsorption amount. In addition, a dosage of 0.1 g of MaA, concentration of 1000 mg/L, pH ranging from 6 to 8, and temperature of about 25 °C were found to be the optimum process conditions for the adsorption of the examined heavy metals, whereas difference in contact time was recorded as follows: 1 h for Pb2+ and Cu2+ ions with adsorption amounts of 75.081 mg/g and 74.054 mg/g, respectively; and 3 h for Cd2+ ion with adsorption equal to 75.530 mg/g. In the analysis of the trend, the coefficients of correlation (R2 = 0.99) of the Langmuir isotherm model were increasingly consistent compared to Freundlich isotherm model (R2 from 0.10 to 0.55), thus indicating that the process to be a homogeneous monomolecular layer adsorption. Moreover, the kinetic aspects were similarly consistent in relation to quasi-secondary kinetic equation, which then further established that the process was primarily controlled by ion exchange, extra-particle, intra-particle, and liquid film diffusion. In addition, research on the potential reusability of MaA adsorbent after being employed to treat heavy metals was also performed. The crystalline phase of the composite after subjected to high temperature indicated wollastonite (CaSiO₃) and gregoryite (Na₂CO₃) as the main mineralogical phases. These minerals are beneficial in the preparation of functional building materials by promoting a sustainable solution for the full recycling of waste glass and contributing to efficient solid waste management and environment protection.

Exploring the atomic-scale dynamics of Fe3O4(001) at catalytically relevant temperatures using FastSTM

Surfaces and interfaces of functional nanoscale materials are typically highly dynamic when employed at elevated temperatures. Both, lateral surface and vertical bulk exchange diffusion processes set in, which can be relevant for applications such as heterogeneous catalysis. Time-resolved scanning tunneling microscopy (STM) is being pushed to ever faster measurement modes to follow such dynamic phenomena in situ. Here, we present FastSTM movies monitoring a range of atomic-scale dynamics of a prototypical reducible oxide catalyst support, Fe3O4(001), at elevated temperatures. Antiphase domain boundaries between two domains of the reconstructed surface exhibit local mobility from around 350 K, while Fe-rich point defects, in a stable equilibrium with the bulk, appear to diffuse in a peculiar zigzag pattern above 500 K. Finally, exploiting the diffusivity of Fe interstitials, we follow the propagation of step edges in the topmost atomic layer of the Fe3O4(001) surface in an oxygen atmosphere.

Selective Sorption of Noble Metals on Polymer Gel Modified with Ionic Liquid.

The solid phase extraction of Au, Ir, Pd, Pt, and Rh on a polymer gel modified with ionic liquid containing methylimidazolium groups (MIA-PG) has been investigated. The positively charged surface of the sorbent is highly suitable for the sorption of stable chlorido complexes of the studied analytes, while the retention of base metals Cu, Fe, Ni, Zn, and Mn is negligible. Optimization experiments performed showed that, at 0.05 M HCl, the degree of sorption of Au, Ir, Pd, and Pt is above 95%, and only for Rh, the maximum degree is 65%; complete elution is achieved in the mixture of thiourea in HCl. The results obtained from the equilibrium adsorption studies are fitted in various adsorption models, such as Langmuir and Freundlich, and the model parameters have been evaluated. The kinetics analysis indicated that the adsorption of Au, Ir, Pd, Pt, and Rh onto the sorbent follows the pseudo-second-order model. Intraparticle diffusion and ion exchange reactions were the rate-limiting steps. Analytical procedures were developed for Pd, Pt, and Rh determination in road dust and soil and for Au determination in copper ore and copper concentrate. The procedures are validated by the analysis of certified reference materials. Analytical figures of merit confirmed their applicability in routine laboratory practice.

Hyperpolarized 129Xe Lung MRI and Spectroscopy in Mechanically Ventilated Mice.

Hyperpolarized (HP) xenon-129 (129Xe) is an inhaled magnetic resonance imaging (MRI) contrast agent with unique spectral and physical properties that can be exploited to quantify pulmonary physiology, including ventilation, restricted diffusion (alveolar-airspace size), and gas exchange. In humans, it has been used to evaluate disease severity and progression in a variety of pulmonary disorders and is approved for clinical use in the United States and United Kingdom. Beyond its clinical applications, the ability of 129Xe MRI to noninvasively assess pulmonary pathophysiology and provide spatially resolved information is valuable for preclinical research. Among animal models, mice are the most widely used due to the accessibility of genetically modified disease models. Here, 129Xe MRI is promising as a minimally invasive, radiation-free, and sensitive technique to longitudinally monitor lung disease progression and therapy response (e.g., in drug discovery). This technique can extend to preclinical applications by incorporating an MRI-triggered, free-breathing apparatus or mechanical ventilator to deliver gas. Here, we describe the steps and provide checklists to ensure robust data collection and analysis, including creating a thermally polarized xenon gas phantom for quality control, optimizing polarization, animal handling (sedation, intubation, ventilation, and care for mice), and protocols for ventilation, restricted diffusion, and gas exchange data. While preclinical 129Xe MRI can be applied in various animal models (e.g., rats, pigs, sheep), this protocol focuses on mice due to the challenges posed by their small anatomy, which are balanced by their affordability and the availability of many disease models.

Assessing tumor microstructure with time-dependent diffusion imaging: Considerations and feasibility on clinical MRI and MRI-Linac.

Quantitative imaging biomarkers (QIBs) can characterize tumor heterogeneity and provide information for biological guidance in radiotherapy (RT). Time-dependent diffusion MRI (TDD-MRI) derived parameters are promising QIBs, as they describe tissue microstructure with more specificity than traditional diffusion-weighted MRI (DW-MRI). Specifically, TDD-MRI can provide information about both restricted diffusion and diffusional exchange, which are the two time-dependent effects affecting diffusion in tissue, and relevant in tumors. However, exhaustive modeling of both effects can require long acquisitions and complex model fitting. Furthermore, several introduced TDD-MRI measurements can require high gradient strengths and/or complex gradient waveforms that are possibly not available in RT settings. In this study, we investigated the feasibility of a simple analysis framework for the detection of restricted diffusion and diffusional exchange effects in the TDD-MRI signal. To promote the clinical applicability, we use standard gradient waveforms on a conventional 1.5 T MRI system with moderate gradient strength (Gmax=45 mT/m), and on a hybrid 1.5 T MRI-Linac system with low gradient strength (Gmax=15 mT/m). Restricted diffusion and diffusional exchange were simulated in geometries mimicking tumor microstructure to investigate the DW-MRI signal behavior and to determine optimal experimental parameters. TDD-MRI was implemented using pulsed field gradient spin echo with the optimized parameters on a conventional MRI system and a MRI-Linac. Experiments in green asparagus and 10 patients with brain lesions were performed to evaluate the time-dependent diffusion (TDD) contrast in the source DW-images. Simulations demonstrated how the TDD contrast was able to differentiate only dominating diffusional exchange in smaller cells from dominating restricted diffusion in larger cells. The maximal TDD contrast in simulations with typical cancer cell sizes and in asparagus measurements exceeded 5% on the conventional MRI but remained below 5% on the MRI-Linac. In particular, the simulated TDD contrast in typical cancer cell sizes (r=5-10µm) remained below or around 2% with the MRI-Linac gradient strength. In patients measured with the conventional MRI, we found sub-regions reflecting either dominating restricted diffusion or dominating diffusional exchange in and around brain lesions compared to the noisy appearing white matter. On the conventional MRI system, the TDD contrast maps showed consistent tumor sub-regions indicating different dominating TDD effects, potentially providing information on the spatial tumor heterogeneity. On the MRI-Linac, the available TDD contrast measured in asparagus showed the same trends as with the conventional MRI but remained close to typical measurement noise levels when simulated in common cancer cell sizes. On conventional MRI systems with moderate gradient strengths, the TDD contrast could potentially be used as a tool to identify which time-dependent effects to include when choosing a biophysical model for more specific tumor characterization.

Dilational rheological properties of extended anionic surfactants at decane-water interface

The dynamic interfacial dilational properties of extended surfactants octadecyl-(polypropylene oxide)m-(polyethylene oxide)n-carboxylic sodium (C18POmEOnC) with different numbers of polypropylene oxide (PO) and polyethylene oxide (EO) groups at the decane–water interface were investigated by means of oscillating drop method. The influences of interface ageing time, dilational frequency, bulk concentration and interfacial pressure on the dilational properties were investigated. The experimental results demonstrate that, at low concentrations, the adsorption film is predominantly influenced by diffusion exchange, while intermolecular interactions at the interface play a more significant role at high concentrations. Beyond the critical micelle concentration (CMC), the primary relaxation process in the adsorption film is driven by the formation of micellar structures. Additionally, the weak hydrophobic PO groups exhibit compressibility and extensibility, facilitating the formation of spring-like helical structures at the decane–water interface. As a result, the dilational modulus increases and the phase angle decreases in low concentration with the increase of PO number. With increasing concentration, the weak hydrophilic EO chains gradually transition from a partially flat state to an upright orientation toward the aqueous phase, forming sublayer structures through polar interactions. At this stage, the increase in EO group chain length has a more pronounced impact on the elastic modulus compared to PO groups. These experimental findings suggest the existence of a mechanistic model for the extended surfactant adsorption films.

Medium-entropy strategy to inhibit the surface Sr segregation and enhance the stability of Sr2Fe1.5Mo0.5O6-δ cathode for CO2 direct electrolysis

Solid oxide electrolysis cell (SOEC) is a promising solid-state electrochemical device that can convert CO2 into CO with high efficiency. However, the poor catalytic activity and Sr segregation of the cathode diminish the electrode reaction, hindering the large-scale application. Herein, a medium-entropy strategy is proposed to suppress the Sr enrichment while enhancing the catalytic activity for CO2. The surface Sr content on Sr2Fe1.2Ni0.1Cu0.1Co0.1Mo0.5O6-δ (SFNCCM) is significantly reduced after the Ni, Cu, and Co co-doping at Fe-site. Moreover, the oxygen surface exchange and bulk diffusion coefficient at 800 °C for SFNCCM oxide reach 2.42 × 10−4 cm2 s−1 and 2.28 × 10−5 cm2 s−1, which are 1.35 and 1.39 times higher than parent Sr2Fe1.5Mo0.5O6-δ(SFM) oxide. At 850 °C and 1.5 V, single with SFNCCM-Sm0.2Ce0.8O6-δ(SDC) composite exhibits a current density of 2.22 A cm−2 with good stability for up to 100 h. The results suggest that the medium-entropy strategy is a promising method to inhibit Sr segregation and enhance the performance of CO2 direct electrolysis.

Reversible image hiding algorithm based on adaptive embedding mechanism

A reversible blind image hiding algorithm (ReBIHA) with help of an adaptive embedding mechanism and a compressive sensing technology is presented in this paper, of which can effectively hide the secret image through a natural meaningful carrier image. In the first phase, a new key generation model (KeyGM) is built by combining random numbers and the plaintext, followed by a newly designed four dimensional chaotic map (NewCM) with stronger pseudo-randomness. Then, the generated chaotic sequence is taken to produce a measurement matrix for compressive sensing. In the second phase, the plain image is sparsely processed, confused, encrypted and compressed to get measurements. Afterward, these measurements are subjected to diffusion and binary exchange to achieve a middle cipher image (MCI). In the third stage, a meaningful carrier image is randomly selected, and integer wavelet transform (IWT) is applied to it, getting one low-frequency and three high-frequency coefficients. Then, the pixels of MCI are subjected by splitting and symmetrically shifting transformation for three element matrices. Finally, these matrices are respectively embedded into the high-frequency coefficients through an adaptive mechanism to find replaceable elements, and a final carrier image hiding secrets (CiHS) can be achieved after performing an inverse IWT. The experimental results show that the proposed algorithm can avoid the extra transmission of original carrier image. Moreover, peak signal-to-noise ratio (PSNR) of reconstructed image can surpass 32 dB at compression ratio 0.5. Especially, the proposed adaptive embedding mechanism can not only achieve blind extraction of secrets well, but also ensure the visual quality for the original carrier image.

Nd Isotopic Equilibration During Channelized Melt Transport Through the Lithosphere: A Feasibility Study Using Idealized Numerical Models

AbstractThis study is motivated by the observed variability in trace element isotopic and chemical compositions of primitive (Si52 wt %) basalts in southwest North America (SWNA) during the Cenozoic transition from subduction to extension. Specifically, we focus on processes that may explain the enigmatic observation that in some localities, basalts with low Ta/Th, consistent with parental melts in a subduction setting, have signatures consistent with continental lithospheric mantle (CLM). In locations with the oldest CLM (Proterozoic and Archean), Cenozoic basalts with low Ta/Th have well below zero. We model channelized magma transport through the CLM using simple 1D transport models to explore the extent to which diffusive and reactive mass exchange can modify Nd isotopic compositions via open system melt‐wallrock interactions. For geologically reasonable channel spacings and volume fractions, we quantify the reactive assimilation rates required for incoming melt with a different than the wall‐rock to undergo a substantial isotopic shift during 10 km channelized melt transport. In the presence of grain boundaries, enhanced diffusion between melt‐rich channels and melt‐poor surrounding rock contributes to isotopic equilibration, however this effect is not enough to explain observations; our models suggest a significant contribution from reactive assimilation of wall‐rock. Additionally our models support the idea that the observed covariability in Ta/Th and in Cenozoic basalts cannot be attributed to transport alone and must also reflect the transition from subduction‐related to extension‐related parental melts in SWNA.

Advanced alginate-based nanofiber aerogels: A synthetic matrix for high-efficiency lysozyme adsorption and controlled release

The development of materials with high lysozyme adsorption is critical for drug delivery and skin wound applications, as it enhances antibacterial properties, stability, and controlled release of therapeutic agents, thereby improving treatment efficacy and safety. Alginate-based nanofiber scaffolds, featuring high surface area and multiple adsorption sites, can efficiently absorb lysozyme and regulate its release through tunable pore channels, offering a promising approach to chronic wound management. In this study, we fabricated poly (vinyl alcohol-co-ethylene) (EVOH) nanofiber-based sodium alginate (ENSA) aerogels using a simple two-step crosslinking procedure. The resulting aerogels, with controllable porosity formed via high-pressure spraying techniques (aerogel film) and molding (aerogel sponge), were evaluated for their high-loading capacity and controllable release of lysozyme. The aerogel film exhibited a remarkable lysozyme adsorption capacity of 1965 ± 36 mg/g, while the aerogel sponge sustained lysozyme release over 14 days. Analysis of the drug-release mechanism through four kinetic models revealed two distinct processes: cation exchange and matrix diffusion. The aerogel's pore structure influenced the diffusion processes, enabling tailored drug release profiles. Additionally, the ENSA aerogels demonstrated good mechanical properties, non-cytotoxicity, and potent antibacterial activity, positioning them as promising materials for skin wound dressings.

Research of surface diffusion and growth of Ni-Pd nanoparticles

ABSTRACT Building upon the foundation of embedded atom method potential, this study employs the Nudged Elastic Band method to computationally investigate the diffusion and structural behaviour of Ni-Pd bimetallic nanoparticles on Wulff surfaces. The results reveal that, whether Ni or Pd serves as the substrate, the energy barrier is significantly lower when adatom exchange occurs with two adjacent (111) interfacet atoms compared to the interfacet of (111) and (100). The optimal diffusion path is identified as the centre-positive diagonal exchange (CPDE). Furthermore, it is observed that the energy of the system decreases after the exchange diffusion with the substrate surface atoms. However, successful exchange diffusion requires overcoming specific energy barriers (>0.43 eV), enabling the deposition of NicorePdshell and PdcoreNishell nanoparticles at low temperatures. In Ni-Pd nanoparticles, surface energy plays a predominant role when the size is very small (Natom≦55), leading to the stable configuration of NicorePdshell nanoclusters. However, as the size increases, the impact of bond energy becomes more pronounced, resulting in an alloyed structure as the stable configuration. Furthermore, in cases where the proportion of Pd atoms is small, all Pd atoms are situated on the surface, displaying a discrete distribution morphology.

Comparison of non-reactive solute transport models for the evaluation of fluid flow in packed beds with implications for heap leaching practice

This study investigated the effects of mean particle size fraction, bottom particle size, particle porosity and wettability on solution scale preferential flow behaviour via step input tracer tests in drip irrigated, narrowly and mixed-sized beds under steady state fluid flux. Nine solute transport models were used to quantify this behaviour reflected in the residence time distribution (RTD) profiles. Four were empirical models: three compartmental model configurations (CM-1, CM-2, CM-3) and tanks-in-series (TIS) model. The remainder five models were semi-empirical: advection dispersion (AD), piston exchange (PE), piston exchange - diffusion variant (PE-D), piston dispersion and exchange (PDE) and piston dispersion and exchange - diffusion variant (PDED). The model fit results showed that the mono-porosity TIS, AD and CM-2 models were the worst performers, while the dual porosity PDE and novel PDE-D models achieved the lowest average error values across the various systems. Higher levels of particle wettability coupled with capillary effects produced peculiar RTD curves that were relatively more difficult for the mono-porosity models to simulate. The model parameters investigated included the longitudinal dispersion coefficient (Dds), dead to total volume fraction (VD/VT), dynamic to total saturation fraction (βd/βT), overall mass transfer coefficient (Kma) and maximum diffusional pore length (X). The results showed that an increase in the average particle size within the beds led to higher VD/VT, Dds and X values, but lower βd/βT and Kma values. These indicate an overall increase in solution scale preferential flow behaviour. Decreased capillary suction and connectivity between particle pores and inter-particle voids were deemed responsible for the results. Higher levels of particle porosity acted as a buffer against these effects. Overall, the results highlight the benefit of the addition of fines (0.1–1 mm particles) during the agglomeration process in heaps to help reduce solution scale preferential flow behaviour and increase liquid hold-up. This is more necessary when the ore has low to moderate levels of porosity (surface area: <2 m2/g) and will also increase the modelling options available as most models performed better fitting data from such beds.