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The occurrence of hydrogen embrittlement often leads to significant fracturing in materials. Thus, a comprehensive understanding of the interactions of hydrogen and its effects on material properties is essential. In this study, first‐principle calculations based on density functional theory are conducted to investigate the adsorption and diffusion characteristics of hydrogen at the Ni/Ni3Al(γ/γ') interface of a Ni‐based single‐crystal superalloy. The results show that hydrogen can stably adsorb onto the γ/γ′ interface, nearby octahedral interstitial sites, and tetrahedral interstitial sites in the γ‐phase. Analysis of the density of states and charge density confirms that the hydrogen atoms formed covalent bonds and ionic bonds with nearby Al atoms. A transition state structure search based on linear synchronous transit (LST) and quadratic synchronous transit (QST) models is utilized to calculate the diffusion paths and energy barriers of the hydrogen atoms between the stable adsorption sites near the interface. In addition, the permeation characteristics of hydrogen atoms at the interface are analyzed. Furthermore, it is confirmed that hydrogen atoms entering the matrix from the interface preferentially occupy the positions of the regular octahedral interstitial sites, diffuse towards adjacent regular 6Ni octahedral interstitial sites through the inclined octahedral interstitial sites between the atomic layers, and converge at the interface. [ABSTRACT FROM AUTHOR]

Purpose: To compare the performance of multi‐echo (ME) and time‐division multiplexing (TDM) sequences for accelerated relaxation‐diffusion MRI (rdMRI) acquisition and to examine their reliability in estimating accurate rdMRI microstructure measures. Method: The ME, TDM, and the reference single‐echo (SE) sequences with six TEs were implemented using Pulseq with single‐band (SB) and multi‐band 2 (MB2) acceleration factors. On a diffusion phantom, the image intensities of the three sequences were compared, and the differences were quantified using the normalized RMS error (NRMSE). Shinnar–Le Roux (SLR) pulses were implemented for the SB‐ME and SB‐SE sequences to investigate the impact of slice profiles on ME sequences. For the in‐vivo brain scan, besides the image intensity comparison and T2‐estimates, different methods were used to assess sequence‐related effects on microstructure estimation, including the relaxation diffusion imaging moment (REDIM) and the maximum‐entropy relaxation diffusion distribution (MaxEnt‐RDD). Results: TDM performance was similar to the gold standard SE acquisition, whereas ME showed greater biases (3–4× larger NRMSEs for phantom, 2× for in‐vivo). T2 values obtained from TDM closely matched SE, whereas ME sequences underestimated the T2 relaxation time. TDM provided similar diffusion and relaxation parameters as SE using REDIM, whereas SB‐ME exhibited a 60% larger bias in the map and on average 3.5× larger bias in the covariance between relaxation‐diffusion coefficients. Conclusion: Our analysis demonstrates that TDM provides a more accurate estimation of relaxation‐diffusion measurements while accelerating the acquisitions by a factor of 2 to 3. [ABSTRACT FROM AUTHOR]

To realize efficient solid‐state batteries, many efforts are directed toward maximizing the bulk Li+ conductivity of sulfide superionic conductors, as demonstrated for the argyrodite‐type materials Li6PS5Cl and Li6PS5Br. Notably, in these archetype materials, the fast Li+ transport benefits from considerable anion disorder on the halide and sulfur sublattices. To further improve the Li+ conductivity, however, one must consider not only the bulk properties of the solid electrolyte (SE) but also microstructural aspects. It is, however, controversially discussed whether grain boundary (GB) transport is generally detrimental for the overall ion conductivity in agyrodite‐type SEs. Thus, by means of atomistic computer simulations, the Li+ ion transport is studied in twist and tilt GBs of Li6PS5Br, revealing that the Br/S site exchange determines whether the presence of GBs deteriorates the ionic conductivity: Whereas the material with 0% Br/S site exchange only shows locally limited bulk diffusion but enhanced GB conductivity, at higher degrees of site exchange, GBs deteriorate Li+ diffusion. These results show that the interplay of GB transport directly depends on the degree of site exchange in argyrodite‐type materials. [ABSTRACT FROM AUTHOR]

Mercury's surface undergoes large temperature gradients between day and night, which repeats periodically over the same longitudes due to its 3:2 spin‐orbit resonance. This effect combined with the orbit's eccentricity, creates hot and cold geographic longitudes. The planet is covered with a highly porous regolith, allowing exospheric atoms to diffuse in depth. By using a 1‐D diffusion model, we studied the subsurface precipitation of gas over the cold and hot longitudes to understand gas retention. This work identifies the cold longitudes as favorable regions to form subsurface reservoirs closer to the surface. Moreover, subsurface reservoirs of adsorbates increase two to three times faster over cold longitudes than over hot longitudes, depending on the surface binding energy distribution of the atoms. We suggest that this result may be related to the observation that Mercury's sodium exosphere persists at later local times over the cold pole. Plain Language Summary: The surface of Mercury experience large temperature differences between day and night, and this repeatedly occurs over the same geographic positions as an orbit of the planet around the Sun lasts exactly one and half Mercury day. Additionally, Mercury's orbit is highly elliptic, causing the planet‐Sun distance to vary. This creates cold and hot geographic longitudes on the planet surface. Mercury's surface is porous and covered with very fine grains which allows gas to diffuse through it. By using a one dimensional model, we study how gases can penetrate Mercury's surface depending on the geographic position. We identify that colder regions are favorable to the formation of shallow gas reservoirs, which grow two to three times faster than over the hottest regions, depending on the gas‐surface interactions. This result may be related to the higher measurements of sodium over the cold geographic longitudes of Mercury, which last through each local afternoon. Key Points: Subsurface diffusion of sodium forms shallow reservoir in the first meter of regolith, which is denser at the cold longitudesGreater surface binding energies increase the amount of sodium retained in the regolith per synodic cycleConvergence of the sodium accumulation should happen on timescales of billions of years, which could lead to the saturation of the regolith [ABSTRACT FROM AUTHOR]

Understanding crystal characteristics down to the atomistic level increasingly emerges as a crucial insight for creating solid state platforms for qubits with reproducible and homogeneous properties. Here, isotope concentration depth profiles in a SiGe/28Si/SiGe heterostructure are analyzed with atom probe tomography (APT) and time‐of‐flight secondary‐ion mass spectrometry down to their respective limits of isotope concentrations and depth resolution. Spin‐echo dephasing times T2echo=128μs$T_2^\mathbf {echo}=128 \,\umu\mathrm{s}$ and valley energy splittings EVS around 200μeV$200 \,\umu\mathrm{e\mathrm{V}}$ have been observed for single spin qubits in this quantum well (QW) heterostructure, pointing toward the suppression of qubit decoherence through hyperfine interaction with crystal host nuclear spins or via scattering between valley states. The concentration of nuclear spin‐carrying 29Si is 50 ± 20ppm in the 28Si QW. The resolution limits of APT allow to uncover that both the SiGe/28Si and the 28Si/SiGe interfaces of the QW are shaped by epitaxial growth front segregation signatures on a few monolayer scale. A subsequent thermal treatment, representative of the thermal budget experienced by the heterostructure during qubit device processing, broadens the top SiGe/28Si QW interface by about two monolayers, while the width of the bottom 28Si/SiGe interface remains unchanged. Using a tight‐binding model including SiGe alloy disorder, these experimental results suggest that the combination of the slightly thermally broadened top interface and of a minimal Ge concentration of 0.3$0.3$% in the QW, resulting from segregation, is instrumental for the observed large EVS=200μeV$E_\mathrm{VS}=200 \,\umu\mathrm{e\mathrm{V}}$. Minimal Ge additions <1%, which get more likely in thin QWs, will hence support high EVS without compromising coherence times. At the same time, taking thermal treatments during device processing as well as the occurrence of crystal growth characteristics into account seems important for the design of reproducible qubit properties. [ABSTRACT FROM AUTHOR]

Diffusion models are increasingly applied in low‐light image enhancement tasks due to their exceptional capability to model data distributions, but most current methods focus only on the original pixel space and neglect the potential of Fourier frequency information. In this article, SFDiff is proposed, a novel low‐light image enhancement method that integrates Fourier frequency information into the diffusion process. Specifically, Fourier transforms are applied at both the image and feature levels to separately enhance the amplitude and phase components, which restores global illumination degradation and positional information. Then a Spatial‐Frequency Fusion (SFF) block is used to fully integrate and interact with the information across spatial and frequency domains. Since illumination degradation is primarily manifested in the amplitude component, a loss function based on maximum likelihood learning is employed to constrain the amplitude component at each step of the sampling process, ensuring that the reverse process maintains an optimal trajectory. Owing to the streamlined network design and the fact that the Fourier transform requires no extra parameters, SFDiff achieves a reduction in parameters of over 35%$35\%$ compared to several state‐of‐the‐art (SOTA) diffusion models and delivers high‐quality enhancement results on multiple real‐world datasets. The code is available at https://github.com/MrWan001/SFDiff. [ABSTRACT FROM AUTHOR]

Intracellular molecules are transported by motor proteins or move by diffusion resulting from random molecular motion. Cardiomyocytes are packed with structures that are crucial for function, but also confine the diffusional spaces, providing cells with a means to control diffusion. They form compartments in which local concentrations are different from the overall, average concentrations. For example, calcium and cyclic AMP are highly compartmentalized, allowing these versatile second messengers to send different signals depending on their location. In energetic compartmentalization, the ratios of AMP and ADP to ATP are different from the average ratios. This is important for the performance of ATPases fuelling cardiac excitation‐contraction coupling and mechanical work. A recent study suggested that compartmentalization modulates the activity of creatine kinase and adenylate kinase in situ. This could have implications for energetic signaling through, for example, AMP‐activated kinase. It highlights the importance of taking compartmentalization into account in our interpretation of cellular physiology and developing methods to assess local concentrations of AMP and ADP to enhance our understanding of compartmentalization in different cell types. [ABSTRACT FROM AUTHOR]

Computational image analysis combined with label‐free imaging has helped maintain its relevance for cell biology, despite the rapid technical improvements in fluorescence microscopy with the molecular specificity of tags. Here, we discuss some computational tools developed in our lab and their application to quantify cell shape, intracellular organelle movement and bead transport in vitro, using differential interference contrast (DIC) microscopy data as inputs. The focus of these methods is image filtering to enhance image gradients, and combining them with segmentation and single particle tracking (SPT). We demonstrate the application of these methods to Escherichia coli cell length estimation and tracking of densely packed lipid granules in Caenorhabditis elegans one‐celled embryos, diffusing beads in solutions of different viscosities and kinesin‐driven transport on microtubules. These approaches demonstrate how improvements to low‐level image analysis methods can help obtain insights through quantitative cellular and subcellular microscopy. [ABSTRACT FROM AUTHOR]

Designing waste forms using the cocktail effect of high‐entropy ceramics can improve the efficiency of ceramic waste forms. In this work, traditional garnet (Y1.2Nd1.8Fe5O12, YIG) and high‐entropy (HE) garnet (Y0.6Gd0.6Sm0.6Eu0.6Dy0.6Fe5O12, HEG) are synthesized through ignition and plasma sintering to form dense ceramic waste forms. The chemical stability of YIG and HEG was studied by using static leaching tests at pH = 3, 5, 7, 9, 11. The results indicate that acidic environments can increase the leaching rate of ceramics. Leaching behavior leads to a decrease in lattice volume, but the elements remain uniformly distributed. The leaching mechanism indicates that YIG and HEG are controlled by dissolution and surface effect in the early stage (1–7 days) of leaching. The leaching mechanism in the later stage (14–42 days) is characterized by diffusion control. The diffusion coefficient of long‐term leaching indicates that HEG is more suitable as the immobilization substrate for high‐level radioactive waste (HLW) than YIG. [ABSTRACT FROM AUTHOR]

Based on the generalized results of experimental methods for studying the viscosity of oligomers—DSC, electron microscopy, NMR spin echo, x‐ray diffraction analysis, edge wetting angles, laser microinterference, atomic force microscopy, dynamic light scattering, plastic flow—an analysis of the features of the supramolecular organization of melts and solutions of epoxy oligomers was carried out. In terms of thermofluctuation approach, a qualitative assessment of the structural elements forming a macroscopic polymer body is given, and direct morphological evidence of their structure, thermodynamic stability, size evolution with temperature changes and elastic‐strain effects is presented. A mathematical apparatus has been developed to describe the destruction of domains in solutions and melts of oligomers. Analytical equations have been proposed for calculating the time of thermofluctuation relaxation of domains. Based on the analysis of the supramolecular structure of dian epoxy oligomers by transmission electron microscopy and translational mobility of oligomer macromolecules in the high temperature region (Tg + 150°C), it has been suggested that a structure such as "flickering clusters" of free volume elements is formed in the oligomer melts. Highlights: Phase diagrams of aromatic and aliphatic epoxy oligomers have been constructed.The influence of molecular weight on the activation energy of diffusion of viscous flow is estimated.It has been shown that the supramolecular structure of epoxy oligomers in the melt contains "flickering clusters."The lifetime of density fluctuations of epoxy oligomers domains in melts has been calculated. [ABSTRACT FROM AUTHOR]

Purpose: To develop a fast denoising framework for high‐dimensional MRI data based on a self‐supervised learning scheme, which does not require ground truth clean image. Theory and Methods: Quantitative MRI faces limitations in SNR, because the variation of signal amplitude in a large set of images is the key mechanism for quantification. In addition, the complex non‐linear signal models make the fitting process vulnerable to noise. To address these issues, we propose a fast deep‐learning framework for denoising, which efficiently exploits the redundancy in multidimensional MRI data. A self‐supervised model was designed to use only noisy images for training, bypassing the challenge of clean data paucity in clinical practice. For validation, we used two different datasets of simulated magnetization transfer contrast MR fingerprinting (MTC‐MRF) dataset and in vivo DWI image dataset to show the generalizability. Results: The proposed method drastically improved denoising performance in the presence of mild‐to‐severe noise regardless of noise distributions compared to previous methods of the BM3D, tMPPCA, and Patch2self. The improvements were even pronounced in the following quantification results from the denoised images. Conclusion: The proposed MD‐S2S (Multidimensional‐Self2Self) denoising technique could be further applied to various multi‐dimensional MRI data and improve the quantification accuracy of tissue parameter maps. [ABSTRACT FROM AUTHOR]

ABSTRACT The present study aimed at investigating and modelling the release behaviour of encapsulated d‐limonene from electrosprayed Alyssum homolocarpum seed gum (AHSG) nanoparticles. For this purpose, release profiles of d‐limonene from 10% or 20% loaded nanocapsules were obtained in deionised water and simulated mouth conditions by a spectrophotometric method. The experimental results showed that complete release takes ranging between 7 and 15 min, depending on the d‐limonene loading and type of release medium. A gradual increase in the flavour release rate over time without initial burst revealed there are several phenomena involved in the release process due to the hydrophilic nature of AHSG nanocapsules. Based on these findings, a mechanistic approach modelled flavour diffusion as a transport process of combined matrix swelling and erosion mechanisms. The model parameters were obtained via best fitting procedure applying simulated annealing (SA) algorithm. The good correlation between the predicted and experimental results of d‐limonene release confirmed validation of the developed model. The simulation results showed that although matrix erosion contributes more than diffusion process in d‐limonene release from AHSG nanocapsules, the model describing the release mechanism as only governed by the erosion is not able to provide accurate predictions of flavour release as compared to the coupled model. [ABSTRACT FROM AUTHOR]

Diffusion of Ge donors in β‐Ga2O3 is studied using a combination of secondary‐ion mass spectrometry, diffusion simulations, and first‐principles calculations, and compared to previous studies on Sn diffusion. Ge is implanted into (2¯$\bar{2}$01)‐oriented samples and annealed at temperatures from 900 to 1050 °C for a total of 8 h. From previous first‐principles calculations, Sn is predicted to diffuse via the formation of a mobile complex with VGa that migrates through a sequence of exchange and rotation jumps. Herein, it is similarly predicted that Ge diffusion is mediated by VGa. However, the microscopic mechanism differs, as Ge can diffuse more easily through exchange combined with complex dissociation, rather than rotational jumps. This is explained by the difference in Ga‐site preference of Ge compared to Sn, and the three‐split mechanism that enables low migration barriers for VGa. The dissociation mechanism leads to a considerably faster transport for Ge as compared to Sn. The experimentally obtained Ge diffusion profiles are successfully fitted using a reaction–diffusion model based on the predicted diffusion mechanism, yielding a migration barrier of 2.5 ± 0.2 eV for the complex. The 2.72 eV obtained from first‐principles calculations is in good agreement with this value. [ABSTRACT FROM AUTHOR]

Enantiomers are ubiquitous in many areas of science, such as pharmaceuticals, agriculture, and food. Nuclear magnetic resonance (NMR) alone is not able to differentiate enantiomers as their spectra are identical. However, these can be distinguished using chiral auxiliaries (such as chiral complexing agents) that form diastereomeric complexes, but absolute identification is still troublesome, usually requiring a chemical reaction with a chiral derivatizing agent. Here, we propose a new method that uses a hybrid mixture of solvating agents in a simple comparison of diffusion NMR experiments, which can discriminate enantiomers in both frequency and diffusion domains, dubbed CHIMERA (CHIral Micelle Enantiomer Resolving Agent). The new method was assessed for twenty‐three small chiral molecules using a combination of BINOL and (−)‐DMEB, a chiral surfactant, and initial results indicate that absolute configuration can be obtained from a simple experiment. [ABSTRACT FROM AUTHOR]

Every biological and physicochemical process occurring in a fluid phase depends on the diffusion coefficient (D) of the species in solution. In the present work, a model to describe and fit the behaviour of D ${D}$ as a function of structure and extensive thermodynamics parameters in binary solutions of linear chain organic molecules is developed. Supporting experimental and computational evidences for this model are obtained by measuring D ${D}$ for a series of n ${n}$ ‐alcohols through a novel surface plasmon resonance method and molecular dynamics simulations. This allows to propose a kind of combined analysis to explain the dependence of D ${D}$ on various thermodynamic and structural parameters. The results suggest that for small linear systems in the range from 0 to 200 g mol−1 and under the assumption that the diffusive activation energy is a linear function of mass, D ${D}$ is strictly dependent on the molecular shape and on the relative strength of the solute‐solvent intermolecular forces represented by a parameter named R. The newly proposed approach can be utilized to characterize and monitor progressive changes in physicochemical properties for any investigated species upon increasing the dimension of the aggregate/molecule along a certain direction. [ABSTRACT FROM AUTHOR]

The obsidian dating method converts the quantity of diffused molecular water within a near‐surface hydration layer to elapsed time using an experimentally derived diffusion coefficient predicted from the structural water content of the glass. Infrared spectroscopic transmission measurements on transparent archaeological samples record vibrational responses of water bands in the near‐infrared region, permitting determination of structural water content (OH), and the amount of diffused ambient water (H2O). In this application, the H2O water band at 5200 cm−1 is measured directly. The accuracy of the approach is assessed by an evaluation of the precision of each contributing variable. The new protocol is evaluated using obsidian artifacts from radiocarbon‐dated deposits at Salamanca Cave in Argentina. [ABSTRACT FROM AUTHOR]

Measurement of ethanol above the skin surface (supradermal) is used to monitor blood alcohol concentrations (BAC) in both legal and consumer settings. Previously, the relationship between supradermal alcohol concentration (SAC) and BAC was described using partial and ordinary differential equations (PDE model: J. Appl. Physiol. 100: 649‐55, 2006). Using a range of BAC profiles by varying absorption times and peak concentrations, the PDE model accurately predicted experimental measures of SAC. Recently, other mathematical models have relied on the PDE model. This paper proposes a new approach to modeling transdermal ethanol kinetics using a mass transfer coefficient and only ordinary differential equations (ODE model). Using a range of BAC profiles, the ODE model performed very similarly to the PDE model. The ODE model had slightly slower washout rates and slightly slower times to peak SAC and to zero SAC. Similar to the PDE model, a sensitivity analysis on the ODE model showed changes in solubility and diffusivity within the stratum corneum, stratum corneum thickness, and the volume of gas above the skin affected model performance. This new model will streamline integration into larger physiologic models, reduce computation time, and decrease the time to transform skin alcohol measurements to blood alcohol concentrations. [ABSTRACT FROM AUTHOR]

Background: Intravoxel incoherent motion (IVIM) diffusion weighted MRI (DWI) has potential for evaluating hepatic fibrosis but image acquisition technique influence on diffusion parameter estimation bears investigation. Purpose: To minimize variability and maximize repeatably in abdominal DWI in terms of IVIM parameter estimates. Study Type: Prospective test–retest and image quality comparison. Subjects: Healthy volunteers (3F/7M, 29.9 ± 12.9 years) and Family Study subjects (18F/12M, 51.7 ± 16.7 years), without and with liver steatosis. Field Strength/Sequence: Abdominal single‐shot echo‐planar imaging (EPI) and simultaneous multi‐slice (SMS) DWI sequences with respiratory triggering (RT), breath‐holding (BH), and navigator echo (NE) at 3 Tesla. Assessment: SMS‐BH, EPI‐NE, and SMS‐RT data from twice‐scanned healthy volunteers were analyzed using 6 × b‐values (0–800 s⋅mm−2) and lower (LO) and higher (HI) b‐value ranges. Family Study subjects were scanned using SMS and standard EPI sequences. The biexponential IVIM model was used to estimate fast‐diffusion coefficient (Df), fraction of fast diffusion (f), and slow‐diffusion coefficient (Ds). Scan time, estimated signal‐to‐noise ratio (eSNR), eSNR per acquisition, and distortion ratio were compared. Statistical Tests: Coefficients of variation (CoV) and Bland Altman analyses were performed for test–retest repeatability. Interclass correlation coefficient (ICC) assessed interobserver agreement with P < 0.05 deemed significant. Results: Within‐subject CoVs among volunteers (N = 10) for f and Ds were lowest in EPI‐NE‐LO (11.6%) and SMS‐RT‐HI (11.1%). Inter‐observer ICCs for f and Ds were highest for EPI‐NE‐LO (0.63) and SMS‐RT‐LO (0.76). Df could not be estimated for most subjects. Estimated eSNR (EPI = 21.9, SMS = 4.7) and eSNR time (EPI = 6.7, SMS = 16.6) were greater for SMS, with less distortion in the liver region (DR‐PE: EPI = 23.6, SMS = 13.1). Data Conclusion: Simultaneous multislice acquisitions had significantly less variability and higher ICCs of Ds, higher eSNR, less distortion, and reduced scan time compared to EPI. Evidence Level: 2 Technical Efficacy: Stage 1 [ABSTRACT FROM AUTHOR]

Many studies show that supranational governance structures (SGS)—understood as international organizations or international treaties—contribute to the global diffusion of public policies. However, we still have a limited understanding of which properties of SGS hasten the number of policy adoptions. To advance this literature, we argue that SGS making legally binding and univocal claims are more likely to act as diffusion accelerators. We demonstrate the suitability of this argument through a case study of the global diffusion of mifepristone approvals, a single‐purpose medicine to terminate pregnancies that has revolutionized abortion services. The analysis supports our expectation. Links to the EU and the Maputo Protocol—the only two considered SGS that make binding claims with clear implications for this policy field—hasten mifepristone approvals. By contrast, ratification of four other treaties—that do not make binding and univocal claims—and exposure to World Health Organization guidelines on medical abortion does not hasten these approvals. [ABSTRACT FROM AUTHOR]

Purpose: To investigate microstructural alterations induced by perfusion fixation in brain tissues using advanced diffusion MRI techniques and estimate their potential impact on the application of ex vivo models to in vivo microstructure. Methods: We used oscillating gradient spin echo (OGSE) and b‐tensor encoding diffusion MRI to examine in vivo and ex vivo microstructural differences in the marmoset brain. OGSE was used to shorten effective diffusion times, whereas b‐tensor encoding allowed for the differentiation of isotropic and anisotropic kurtosis. Additionally, we performed Monte Carlo simulations to estimate the potential microstructural changes in the tissues. Results: We report large changes (˜50%–60%) in kurtosis frequency dispersion (OGSE) and in both anisotropic and isotropic kurtosis (b‐tensor encoding) after perfusion fixation. Structural MRI showed an average volume reduction of about 10%. Monte Carlo simulations indicated that these alterations could likely be attributed to extracellular fluid loss possibly combined with axon beading and increased dot compartment signal fraction. Little evidence was observed for reductions in axonal caliber. Conclusion: Our findings shed light on advanced MRI parameter changes that are induced by perfusion fixation and potential microstructural sources for these changes. This work also suggests that caution should be exercised when applying ex vivo models to infer in vivo tissue microstructure, as significant differences may arise. [ABSTRACT FROM AUTHOR]

Purpose: This study aims to assess how T2 heterogeneity biases IMPULSED‐derived metrics of tissue microstructure in solid tumors and evaluate the potential of estimating multi‐compartmental T2 and microstructural parameters simultaneously. Methods: This study quantifies the impact of T2 relaxation on IMPULSED‐derived microstructural parameters using computer simulations and in vivo multi‐TE IMPULSED MRI in five tumor models, including brain, breast, prostate, melanoma, and colon cancer. A comprehensive T2 + IMPULSED method was developed to fit multi‐compartmental T2 and microstructural parameters simultaneously. A Bayesian model selection approach was carried out voxel‐wisely to determine if the T2 heterogeneity needs to be included in IMPULSED MRI in cancer. Results: Simulations suggest that T2 heterogeneity has a minor effect on the estimation of d in tissues with intermediate or high cell density, but significantly biases the estimation of vin$$ {v}_{in} $$ with low cell density. For the in vivo animal experiments, all IMPULSED metrics except vin$$ {v}_{in} $$ are statistically independent on TE. For B16 tumors, the IMPULSED‐derived vin$$ {v}_{in} $$ exhibited a notable increase with longer TEs. For MDA‐MB‐231 tumors, IMPULSED‐derived vin$$ {v}_{in} $$ showed a significant increase with increasing TEs. The T2 + IMPULSED‐derived T2in$$ {T}_2^{in} $$ of all five tumor models are consistently smaller than T2ex$$ {T}_2^{ex} $$. Conclusions: The findings from this study highlight two key observations: (i) TE has a negligible impact on IMPULSED‐derived cell sizes, and (ii) the TE‐dependence of IMPULSED‐derived intracellular volume fractions used in T2 + IMPULSED modeling to estimate T2in$$ {T}_2^{in} $$ and T2ex$$ {T}_2^{ex} $$. These insights contribute to the ongoing development and refinement of non‐invasive MRI techniques for measuring cell sizes. [ABSTRACT FROM AUTHOR]

Objective Methods Results Conclusions We investigate the contributions of state and local governments to the diffusion of American fair housing law and policy, focusing on the period from 1919 to 1968, prior to similar legal requirements and policies being approved at the federal level.Relying on archival data obtained at two presidential libraries, our findings provide insights into diffusion's political effects.Myriad state and local laws, constituting breakthroughs that spread horizontally and/or bottom‐up, preceded similar requirements in the national Fair Housing Act of 1968 and implementation policies subsequently adopted by the federal bureaucracy.Progressive subnational governments can promote the rights of politically marginalized individuals and groups when the national government and other subnational jurisdictions do not. States and localities can use desegregation approaches not available at the federal level. [ABSTRACT FROM AUTHOR]

Mass transport in porous systems is inherently complex, but at the same also of utmost importance for large‐scale industrial processes such as heterogeneous catalysis. For each of the different length scales of diffusive motion potentially involved or relevant, specific characterization techniques have been developed and successfully applied over the years – including, but not limited to pulsed field gradient nuclear magnetic resonance (PFG‐NMR) spectroscopy, zero length column (ZLC) measurements and inverse gas chromatography (iGC). While each of these methods can deliver detailed information on certain types of diffusion, none of them are capable of delivering a full picture of mass transport across multiple length scales alone. In this context, the goal of the present work was to evaluate the technical feasibility and characterization potential of the hyphenated combination of PFG‐NMR and iGC in a coupled experimental setup. Challenges, advantages, and limitations of this approach are discussed using the example of propane adsorption and diffusion in two different zeolite catalysts (Mg(H)‐ZSM‐5 and Silicalite‐1). It is shown that the simultaneous detection of self‐diffusion on short length scales (as probed by PFG‐NMR) and transport diffusion covering longer distances (detectable by iGC) cannot be realized under the used conditions, essentially due to the lack of kinetic control at higher reactant loadings. The key advantage of the developed coupled setup is the ability of the iGC instrument to provide defined and readily variable levels of catalyst loading, which enables advanced pore connectivity studies by PFG‐NMR and yields thermodynamic data on reactant adsorption at the same time. [ABSTRACT FROM AUTHOR]

Transformation of maleic anhydride (MA) into succinic anhydride (SA) through the development of high‐performance catalysts is an appealing approach from a sustainable development perspective. Herein, a core‐shell catalyst with silicate‐1 supported and MCM‐41 encapsulated nickel was prepared, which exhibited extraordinarily high MA conversion (99.8 %) and SA selectivity (99.9 %). Detailed structural characterizations and catalytic evaluation demonstrated that the core‐shell catalyst derived from the liquid deposition method is a hierarchically porous material with tunable shell thicknesses, possessing strong interaction between Ni particles and the supports. Key to this success is the MCM‐41 shell that covered the defects such as silanol nests on the surface of the silicate‐1 zeolite, diminishing both the surface and intra‐particle diffusion barriers, thus the specially‐designed catalyst achieved high activity under rather mild conditions (100 °C, 3.0 MPa), which is 59 % higher than the conventional silicate‐1 supported Ni catalyst. Furthermore, the mesoporous MCM‐41 shell plays a crucial role in minimizing the leaching and sintering of Ni particles, thereby bolstering catalytic stability. Overall, the research provides a new approach for the rational design to optimize the performance of hydrogenation catalysts and introduces a novel idea to enhance the activity and stability of Ni‐supported catalysts. [ABSTRACT FROM AUTHOR]

For independency from the fossil fuels and to save environment, we need to move toward the green energies, which requires better energy storage devices, especially for usage in electric vehicles. Li‐ion and beyond‐lithium insertion batteries are promising to this aim. However, they suffer from some inherent limitations which must be understood to allow their development and pave the way to find suitable energy storage alternatives. It is found that each positive or negative electrode material (cathode or anode) of the intercalation batteries has its own behavioral (charge‐discharge) properties. The modification of preparation parameters (composition, loading density, porosity, particle size, etc.) may improve some aspects of the electrode performance, but cannot change the intrinsic property of the electrode itself. Accordingly, these properties are called as the "inherent behavior characteristics" of the active material. It is concluded that the behavior of a specific electrode substance, even following different preparation routes, depends only on diffusion mechanisms. This work shows that the inherent electrode properties can be visualized by representation of current density vs. capacity. [ABSTRACT FROM AUTHOR]

Adopting an advanced microscopic model of the Au–graphite interaction, a systematic study of Au nanoclusters (up to sizes of 11 238 atoms) on graphene and on graphite is carried out to explore their structure and energy landscape. Using parallel tempering molecular dynamics, structural distribution as a function of temperature is calculated in the entire temperature range. Low‐energy structures are identified through a combination of structural optimization and Wulff–Kaischew construction which are then used to explore the energy landscape. The potential energy surface (PES), which is energy as a function of translation and rotation, is calculated for a few Au nanoclusters along specific directions on carbon lattice. Minimum‐energy pathways are identified on the PES indicating a reduced barrier for pathways involving simultaneous rotation and translation. Diffusion simulations of Au233 on graphite show that diffusion mechanism is directly related to the PES, and the information of the cluster pinning events is already present in the PES. Finally, a comparison of various interaction models highlights the importance of reasonably correct Au–C interactions which is crucial for studying the energy landscape and cluster sliding. [ABSTRACT FROM AUTHOR]

Reported depth profiles of hydrogen in plasma‐exposed n‐Si samples can be fitted with a simple model of hydrogen transport by negative and neutral species (H− and H0) accompanied by a reversible formation of hydrogen–donor pairs (HD) and by an irreversible production of mobile dimers H2A—in particular by a bulk pairing reaction of the H− and H0 species. Contrary to a complicated behavior of hydrogen found in p‐Si (with multiple independent states for positive ions and passivated boron), the situation in n‐Si appears to be much simpler as only single states for H−, H0, and HD are sufficient for profile reproduction. The parameters deduced from the profiles are the diffusivity of H−, the characteristic electron concentration marking equal contributions of H− and H0 into hydrogen transport, and the diffusivity of H2A dimers (in the available temperature range 120–225 °C). [ABSTRACT FROM AUTHOR]

Mafic magma recharge of crustal reservoirs and subsequent magma mixing has been considered a direct trigger of volcanic eruptions. However, although recharge frequently occurs in many active volcanoes, it rarely leads to an eruption immediately, making its role as a trigger ambiguous. Sakurajima volcano, Japan, has vigorously erupted three times since the 15th century following a common process; mixed magmas after recharge were once stored in a shallow, thick conduit before each eruption (conduit pre‐charge). We reconstructed the magma migration with a high time resolution by diffusion modeling on orthopyroxene and magnetite. Orthopyroxene phenocrysts recorded prolonged diffusive re‐equilibration timescales of years or more after recharge‐and‐mixing. Magnetite, which has the fastest elemental diffusivity among the phenocrysts examined, predominantly lacks zoning. This demonstrates that the mineral phase was re‐equilibrated with surrounding magma and homogenized via elemental diffusion after the final magmatic perturbation, implying the final repose of the shallow pre‐charged magma body for more than several tens of days. After this shallow stagnation period, the Plinian magmas began to ascend and reached the surface within 55 hr. Mass balance calculations show that crystallization‐driven vesiculation upon pre‐charge can produce overpressure sufficient to cause an eruption. The Sakurajima cases demonstrate the hierarchical timescales of trigger processes leading to the explosive eruptions. Plain Language Summary: Understanding how volcanic eruptions are triggered is an important scientific challenge that directly contributes to studying volcanic hazard. Volcanic ejecta often shows evidence of the injection of hot magma into magma reservoirs, with the injection often considered an eruption trigger. However, such injection is frequently observed in many active volcanoes, while rarely leads to an eruption immediately. Sakurajima volcano, Japan, is an excellent test field to understand the trigger mechanism because three large‐scale eruptions occurred in historical time following a similar sequence. A previous study has revealed that the Sakurajima magmas once stagnated in a shallow, thick conduit before each of the eruptions. In this study, we conducted elemental diffusion simulation of phenocrysts and constrained the duration of the shallow stagnation to be more than tens of days. We also found that magma injection occurred repeatedly but did not immediately lead to the eruptions. Crystallization within the shallow conduit, which causes vesiculation (over‐pressurization) of magma, could have finally led to the eruptions. To prepare to the next large eruption at Sakurajima, one should consider the multiple cascading trigger process, which includes a shallow stagnation period followed by fast magma ascent to the surface. Key Points: We investigated the timescales of hierarchical trigger processes leading to three historical eruptions at Sakurajima volcanoDiffusion modeling reveals that magma reservoir recharges occurred repeatedly but did not immediately lead to eruptionsAfter a shallow stagnation period of more than several tens of days, magma began to ascend and reached the surface within 55 hr [ABSTRACT FROM AUTHOR]

Research question/issue: This study examines the influence of group behavior on board gender diversity and identifies obstacles to its diffusion. It investigates whether boards are influenced by group behavior in determining their gender composition and explores barriers that impede the diffusion process. Research findings/insights: Analyzing a network of over 18,000 US‐listed boards observed over 20 years, we find a pattern of mimetic behavior, whereby boards imitate the proportion of women on boards (WoB) among their directly tied boards. We also identify resistant firms with low representation of women on their boards. Our findings suggest that, among those boards, there are heavily male‐dominated boards resisting the appointment of women, even when surrounded by women directors among their tied boards. The diffusion of board gender diversity is slowed down by these resistant boards, hindering the overall progress in increasing gender diversity within the board network. Theoretical/academic implications: This research contributes insights into group behavior and resistance in board gender diversity. Adopting a network theory lens, our study sheds light on interactions between firms and their connected companies in terms of imitation practices. Drawing on social identity theory, we highlight the significance of the resistance to increasing women's representation exhibited by some boards. Practitioner/policy implications: Resistant boards, despite group pressure, slow down the diffusion of board gender diversity within the network, leading to overall stagnation. Understanding the sources of resistance allows an exploration of alternative measures to promote diversity without rigid mandates. [ABSTRACT FROM AUTHOR]

Intravoxel incoherent motion (IVIM) MRI has emerged as a valuable technique for the assessment of tissue characteristics and perfusion. However, there is limited knowledge about the relationship between IVIM‐derived measures and changes at the level of the vascular network. In this study, we investigated the potential use of IVIM MRI as a noninvasive tool for measuring changes in cerebral vascular density. Variations in quantitative immunohistochemical measurements of the vascular density across different regions in the rat brain (cortex, corpus callosum, hippocampus, thalamus, and hypothalamus) were related to the pseudo‐diffusion coefficient D* and the flowing blood fraction f in healthy Wistar rats. We assessed whether region‐wise differences in the vascular density are reflected by variations in the IVIM measurements and found a significant positive relationship with the pseudo‐diffusion coefficient (p < 0.05, β = 0.24). The effect of cerebrovascular alterations, such as blood–brain barrier (BBB) disruption on the perfusion‐related IVIM parameters, is not well understood. Therefore, we investigated the effect of BBB disruption on the IVIM measures in a rat model of metabolic and vascular comorbidities (ZSF1 obese rat) and assessed whether this affects the relationship between the cerebral vascular density and the noninvasive IVIM measurements. We observed increased vascular permeability without detecting any differences in diffusivity, suggesting that BBB leakage is present before changes in the tissue integrity. We observed no significant difference in the relationship between cerebral vascular density and the IVIM measurements in our model of comorbidities compared with healthy normotensive rats. [ABSTRACT FROM AUTHOR]

In this paper, we consider a diffusive predator–prey model with spatial memory of prey and gestation delay of predator. For the system without delays, we study the stability of the positive equilibrium in the case of diffusion and no diffusion, respectively. For the delayed model without diffusions, the existence of Hopf bifurcation is discussed. Further, we investigate the stability switches of the model with delays and diffusions when two delays change simultaneously by calculating the stability switching curves and obtain the existence of Hopf bifurcation. We also calculate the normal form of Hopf bifurcation to determine the direction of Hopf bifurcation and the stability of bifurcation periodic solutions. Finally, numerical simulations verify the theoretical results. [ABSTRACT FROM AUTHOR]

Highlights This work investigates the comprehensive exploration of transport properties in natural rubber/graphene oxide‐silica hybrid core‐shell (NR/GSC) nanocomposites, focusing on diffusion, sorption behavior, swelling parameters, and gas permeability. The study evaluates the performance of the composite membranes concerning oxygen and nitrogen gas permeability (71.3% and 68.48% reduction, respectively). The experimental results reveal the sorption behavior, swelling parameters, and transport coefficients of NR/GSC composites, providing valuable insights into the material's behavior in different environments. Among various compositions, GSC10 stands out as the optimal composition, exhibiting superior diffusion and gas permeability behavior compared to other compositions. How the filler geometry and concentration are interconnected on the transport properties is carefully dissected, offering a deeper comprehension of the correlation between filler characteristics and composite performance. The study predicts that the Peppas‐Sahlin model and Affine model for mole percentage solvent uptake and molecular mass between successive crosslinks, respectively, best fit experimental values. This work contributes to the growing knowledge in the field of nanocomposites, providing a meticulous perspective on the transport properties of NR/GSC membranes and emphasizing the superior performance of the GSC10 composition. NR/GSC hybrid nanocomposites showed reduced solvent uptake. A 71.3% reduction in oxygen and 68.48% reduction in nitrogen permeation. Theoretically modeled using Peppas‐Sahlin, Korsmeyer‐Peppas, Nielsen and s GSC nanoparticles shows excellent dispersion in NR matrix Enhanced fuel efficiency and reduced environmental footprint in tire manufacturing technology. [ABSTRACT FROM AUTHOR]

This study utilized molecular dynamics simulations (MD) to explore the impact of cyclization and lysine charges on antimicrobial peptides (AMPs) across eight simulation boxes designed with water and water‐sodium dodecyl sulfate (SDS) micelles. Cyclic AMPs with positively charged lysine residues (c‐AMP+) displayed increased stability in both environments compared to linear AMPs (l‐AMP+), with removal of positive charges notably destabilizing the linear form in water‐SDS. Findings revealed enhanced mobility due to cyclization and charged lysine residues, further boosted by SDS presence. Notably, lysine residues exhibited a stronger affinity for SDS than tryptophan and phenylalanine, especially lysine number 5. Analysis extended to peptide backbone conformation and electronic features, showing cyclization's greater impact on psi and phi angles over charge presence, with linear AMPs displaying lower reactivity than cyclic counterparts. This research underscores the significance of cyclization and lysine charges in AMP behavior, suggesting the potential of c‐AMP+ for further development owing to their improved stability, mobility, and membrane interactions. [ABSTRACT FROM AUTHOR]

Silicone rubber is a good candidate as a carrier of small molecules in such applications as drug, fragrance and semiochemical delivery. When one matrix is loaded, the molecular interactions between the molecules and the matrix may affect their release rates. For this reason, it is important to investigate the effects of molecular interactions on release to better develop delivery systems with desirable release rates. In this study, the mass transfer and diffusion coefficients of three model molecules (i.e., octanol, octyl acetate, and octyl butyrate) were determined by monitoring their release from silicone rubber sheets loaded using headspace gas chromatography–mass spectrometry. Differential scanning calorimetry was used to characterize the plasticizing effects and Fourier transform infrared spectroscopy was used to characterize the molecular interactions. It was found that the release of octanol conformed to the Fickian diffusion pattern at 1 wt% initial concentration but deviated as the concentration increased due to hydrogen bonding between octanol and the silanol group of the silica filler. When two small molecules were released simultaneously, the effects of one molecule on the diffusion coefficient of the other differed, a result explained by the competing effects of plasticizing and hydrogen bonding. [ABSTRACT FROM AUTHOR]

This research focuses on comparing the properties of molybdenum disulfide (MoS2) diffused coir fiber polyester composites (MCF‐PCs) with neat coir fiber polyester composites (NCF‐PCs) and exploring its applications in various industrial sectors such as automotive, construction and manufacturing, where mechanical strength and fire resistance are critical factors. The study aims to investigate the physical, mechanical, thermal degradation, fire performance, and vibration properties of these composites. Compression molding was used to develop composites with different coir fiber loadings (10%, 20%, and 30% by weight). MoS2 nanoparticles diffused on the fiber surface significantly improved mechanical characteristics, thermal stability, and fiber‐matrix compatibility. The findings indicate better crystallinity and physical properties in MCF‐PCs compared to NCF‐PCs. Morphological observations confirmed improved fiber‐matrix compatibility in MoS2‐diffused fiber composites with polyester. The MCF‐PC with 20% loading exhibited the highest tensile (28 ± 1.24 MPa), flexural (50 ± 0.50 MPa), and impact (15 ± 1.01 kJ/m2) strength. The flame retardancy of the composites was evaluated using a horizontal combustion test apparatus. In addition, MCF‐PCs exhibited better flame retardancy as evidenced by lower flame propagation velocity (9 ± 0.20 mm/min) and increased ignition time (13 ± 0.29 Sec). The MCF‐PC with 20% loading shows maximum natural frequencies of 77 ± 4.1 Hz. Highlights: This study investigated MoS2‐diffused coir fiber‐reinforced polyester composites.Fiber‐matrix adhesion can be improved with modified fiber‐reinforced composites.The MoS2 diffusion on fibers improved the physical and mechanical properties of polyester composites.The MoS2 diffusion on fibers enhanced the thermal and vibrational characteristics of polyester composites.MoS2‐diffused natural fiber composites offer considerable research potential. [ABSTRACT FROM AUTHOR]

The unstable solid electrolyte interface (SEI) formed on the surface of Li metal can induce dendrite growth, resulting in capacity fading, battery short circuit, and other problems, thus hindering the practical application of Li metal battery. In order to obtain stable and effective SEI, it is an effective strategy to construct an ideal artificial SEI (ASEI) by regulating the composition and structure of the interface. Among the inorganic materials used in the construction of ASEI, carbon quantum dots (CQDs) stand out as promising material due to their small size and abundant active sites. Herein, benefiting from the fluidity, surface smoothness, and high reactivity of liquid metal, combined with the use of N‐doped CQDs as dispersing particles, a surface modification method to achieve uniform dispersion of particles within the liquid metal is proposed. This technique offers a low‐cost solution for achieving uniform dispersion of little quantities of N‐doped CQDs (single dose < 0.1 mg cm−2) while ensuring enhanced interface adhesion to realize the construction of dense, strong and uniform ASEI. The corresponding symmetrical cells show lower voltage polarization and outstanding cycling stability than the bare Li electrode. [ABSTRACT FROM AUTHOR]

This study aims to investigate how inert gas affects the partial pressure of alveolar and venous blood using a fast and accurate operator splitting method (OSM). Unlike previous complex methods, such as the finite element method (FEM), OSM effectively separates governing equations into smaller sub‐problems, facilitating a better understanding of inert gas transport and exchange between blood capillaries and surrounding tissue. The governing equations were discretized with a fully implicit finite difference method (FDM), which enables the use of larger time steps. The model employed partial differential equations, considering convection‐diffusion in blood and only diffusion in tissue. The study explores the impact of initial arterial pressure, breathing frequency, blood flow velocity, solubility, and diffusivity on the partial pressure of inert gas in blood and tissue. Additionally, the effects of anesthetic inert gas and oxygen on venous blood partial pressure were analyzed. Simulation results demonstrate that the high solubility and diffusivity of anesthetic inert gas lead to its prolonged presence in blood and tissue, resulting in lower partial pressure in venous blood. These findings enhance our understanding of inert gas interaction with alveolar/venous blood, with potential implications for medical diagnostics and therapies. [ABSTRACT FROM AUTHOR]

In this study, a series of biodegradable poly(butylene alkylene carboxylate‐co‐terephthalate) copolymers with varying methylene numbers in the alkylene units (0, 2, 4, and 8) are synthesized. These copolymers, namely, poly(butylene oxalate‐co‐terephthalate) (PBOT), poly(butylene succinate‐co‐terephthalate) (PBST), poly(butylene adipate‐co‐terephthalate) (PBAT), and poly(butylene sebacate‐co‐terephthalate) (PBSeT), are prepared with nearly identical structural and molar compositions. The objective of this study is to comprehensively examine the impact of alkylene unit length on the barrier properties of the materials, delving into aspects such as crystallinity, free volume, molecular chain mobility, as well as adsorption and diffusion of gases within the materials. The findings indicate a decrease in crystallinity from 17.2% for PBOT to 10.2% for PBSeT as the alkylene chain length increases, while maintaining the same chemical composition. Concurrently, the fractional free volume increases from 0.9% to 2.6%, and the melt flow activation energy decreases from 106.6 to 52.1 kJ mol−1. Importantly, theoretical calculations are performed, demonstrating that the predominant site for gas adsorption and diffusion is within the material's free volume. These combined observations indicate a gradual decrease in barrier properties as the number of methylene groups increases. [ABSTRACT FROM AUTHOR]

Complementary aspects of tissue microstructure can be studied with diffusion‐weighted imaging (DWI). However, there is no consensus on how to design a diffusion acquisition protocol for multiple models within a clinically feasible time. The purpose of this study is to provide a flexible framework that is able to optimize the shell acquisition protocol given a set of DWI models. Eleven healthy subjects underwent an extensive DWI acquisition protocol, including 15 candidate shells, ranging from 10 to 3500 s/mm2. The proposed framework aims to determine the optimized acquisition scheme (OAS) with a data‐driven procedure minimizing the squared error of model‐estimated parameters. We tested the proposed method over five heterogeneous DWI models exploiting both low and high b‐values (i.e., diffusion tensor imaging [DTI], free water, intra‐voxel incoherent motion [IVIM], diffusion kurtosis imaging [DKI], and neurite orientation dispersion and density imaging [NODDI]). A voxel‐level and region of interest (ROI)‐level analysis was conducted over the white matter and in 48 fiber bundles, respectively. Results showed that acquiring data for the five abovementioned models via OAS requires 14 min, compared with 35 min for the joint recommended acquisition protocol. The parameters derived from the reference acquisition scheme and the OAS are comparable in terms of estimated values, noise, and tissue contrast. Furthermore, the power analysis showed that the OAS retains the potential sensitivity to group‐level differences in the parameters of interest, with the exception of the free water model. Overall, there is a linear correspondence (R2 = 0.91) between OAS and reference‐derived parameters. In conclusion, the proposed framework optimizes the shell acquisition scheme for a given set of DWI models (i.e., DTI, free water, IVIM, DKI, and NODDI), combining low and high b‐values while saving acquisition time. [ABSTRACT FROM AUTHOR]

The glymphatic system is a system of specialized perivascular spaces in the brain that facilitates removal of toxic waste solutes from the brain. Evaluation of glymphatic system function by means of magnetic resonance imaging (MRI) has thus far been largely focused on rodents because of the limitations of intrathecal delivery of gadolinium‐based contrast agents to humans. This review discusses MRI methods that can be employed clinically for glymphatic‐related measurements intended for early diagnosis, prevention, and the treatment of various neurological conditions. Although glymphatic system‐based MRI research is in its early stages, recent studies have identified promising noninvasive MRI markers associated with glymphatic system alterations in neurological diseases. However, further optimization in data acquisition, validation, and modeling are needed to investigate the glymphatic system within the clinical setting. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the use of pre‐excitation gradients for eddy current–nulled convex optimized diffusion encoding (Pre‐ENCODE) to mitigate eddy current–induced image distortions in diffusion‐weighted MRI (DWI). Methods: DWI sequences using monopolar (MONO), ENCODE, and Pre‐ENCODE were evaluated in terms of the minimum achievable echo time (TE min$$ {}_{\mathrm{min}} $$) and eddy current‐induced image distortions using simulations, phantom experiments, and in vivo DWI in volunteers (N=6$$ N=6 $$). Results: Pre‐ENCODE provided a shorter TE min$$ {}_{\mathrm{min}} $$ than MONO (71.0 ±$$ \pm $$ 17.7ms vs. 77.6 ±$$ \pm $$ 22.9ms) and ENCODE (71.0 ±$$ \pm $$ 17.7ms vs. 86.2 ±$$ \pm $$ 14.2ms) in 100%$$ \% $$ of the simulated cases for a commercial 3T MRI system with b‐values ranging from 500 to 3000 s/mm 2$$ {}^2 $$ and in‐plane spatial resolutions ranging from 1.0 to 3.0mm 2$$ {}^2 $$. Image distortion was estimated by intravoxel signal variance between diffusion encoding directions near the phantom edges and was significantly lower with Pre‐ENCODE than with MONO (10.1%$$ \% $$ vs. 22.7%$$ \% $$, p=6−5$$ p={6}^{-5} $$) and comparable to ENCODE (10.1%$$ \% $$ vs. 10.4%$$ \% $$, p=0.12$$ p=0.12 $$). In vivo measurements of apparent diffusion coefficients were similar in global brain pixels (0.37 [0.28,1.45]×10−3$$ \times 1{0}^{-3} $$ mm 2$$ {}^2 $$/s vs. 0.38 [0.28,1.45]×10−3$$ \times 1{0}^{-3} $$mm 2$$ {}^2 $$/s, p=0.25$$ p=0.25 $$) and increased in edge brain pixels (0.80 [0.17,1.49]×10−3$$ \times 1{0}^{-3} $$ mm 2$$ {}^2 $$/s vs. 0.70 [0.18,1.48]×10−3$$ \times 1{0}^{-3} $$mm 2$$ {}^2 $$/s, p=0.02$$ p=0.02 $$) for MONO compared to Pre‐ENCODE. Conclusion: Pre‐ENCODE mitigated eddy current–induced image distortions for diffusion imaging with a shorter TE min$$ {}_{\mathrm{min}} $$ than MONO and ENCODE. [ABSTRACT FROM AUTHOR]

Purpose: To determine whether intravoxel incoherent motion (IVIM) describes the blood perfusion in muscles better, assuming pseudo diffusion (Bihan Model 1) or ballistic motion (Bihan Model 2). Methods: IVIM parameters were measured in 18 healthy subjects with three different diffusion gradient time profiles (bipolar with two diffusion times and one with velocity compensation) and 17 b‐values (0–600 s/mm2) at rest and after muscle activation. The diffusion coefficient, perfusion fraction, and pseudo‐diffusion coefficient were estimated with a segmented fit in the gastrocnemius medialis (GM) and tibialis anterior (TA) muscles. Results: Velocity‐compensated gradients resulted in a decreased perfusion fraction (6.9% ± 1.4% vs. 4.4% ± 1.3% in the GM after activation) and pseudo‐diffusion coefficient (0.069 ± 0.046 mm2/s vs. 0.014 ± 0.006 in the GM after activation) compared to the bipolar gradients with the longer diffusion encoding time. Increased diffusion coefficients, perfusion fractions, and pseudo‐diffusion coefficients were observed in the GM after activation for all gradient profiles. However, the increase was significantly smaller for the velocity‐compensated gradients. A diffusion time dependence was found for the pseudo‐diffusion coefficient in the activated muscle. Conclusion: Velocity‐compensated diffusion gradients significantly suppress the IVIM effect in the calf muscle, indicating that the ballistic limit is mostly reached, which is supported by the time dependence of the pseudo‐diffusion coefficient. [ABSTRACT FROM AUTHOR]

Background: The uterus undergoes dynamic changes throughout the menstrual cycle. Diffusion kurtosis imaging (DKI) is based on the non‐Gaussian distribution of water molecules and can perhaps represent the changes of uterine microstructure. Purpose: To investigate the temporal changes in DKI‐parameters of the normal uterine corpus and cervix during the menstrual cycle. Study Type: Prospective. Population: 21 healthy female volunteers (26.64 ± 4.72 years) with regular menstrual cycles (28 ± 7 days). Field Strength/Sequence: Readout segmentation of long variable echo‐trains (RESOLVE)‐based DKI and fast spin‐echo T2‐weighted sequences at 3.0T. Assessment: Each volunteer was scanned during the menstrual phase, ovulatory phase, and luteal phase. Regions of interest (ROI) were manually delineated in the endometrium, junctional zone, and myometrium of the uterine body, and in the mucosal layer, fibrous stroma layer, and loose stroma layer of the cervix. The mean Kapp (diffusion kurtosis coefficient), Dapp (diffusion coefficient), and ADC (apparent diffusion coefficient) values were measured in the ROI. Statistical Tests: ANOVA with Bonferroni or Tamhane correction. Intraclass correlation coefficient (ICC) for assessing agreement. P < 0.05 was considered statistically significant. Results: During the menstrual cycle, the highest Kapp (0.848 ± 0.184) and lowest Dapp (1.263 ± 0.283 *10−3 mm2/sec) values were found in the endometrium during the menstrual phase. The Dapp values for the myometrium were significantly higher than those of the endometrium and the junctional zone in every phase. Meanwhile, the Dapp values for the three zonal structures of the cervix during ovulation were significantly higher than those during the luteal phase. However, there was no significant difference in the ADC values of the loose stroma between ovulation and the luteal phase (P = 0.568). The reproducibility of DKI parameters was good (ICC, 0.857–0.944). Data Conclusion: DKI can show dynamic changes of the normal uterus during the menstrual cycle. Level of Evidence: 2 Technical Efficacy: Stage 2 [ABSTRACT FROM AUTHOR]

Objective: Subcortical nuclei such as the thalamus and striatum have been shown to be related to seizure modulation and termination, especially in drug‐resistant epilepsy. Enhance diffusion‐weighted imaging (eDWI) technique and tri‐component model have been used in previous studies to calculate apparent diffusion coefficient from ultra high b‐values (ADCuh). This study aimed to explore the alterations of ADCuh in the bilateral thalamus and striatum in MRI‐negative drug‐resistant epilepsy. Methods: Twenty‐nine patients with MRI‐negative drug‐resistant epilepsy and 18 healthy controls underwent eDWI scan with 15 b‐values (0–5000 s/mm2). The eDWI parameters including standard ADC (ADCst), pure water diffusion (D), and ADCuh were calculated from the 15 b‐values. Regions‐of‐interest (ROIs) analyses were conducted in the bilateral thalamus, caudate nucleus, putamen, and globus pallidus. ADCst, D, and ADCuh values were compared between the MRI‐negative drug‐resistant epilepsy patients and controls using multivariate generalized linear models. Inter‐rater reliability was assessed using the intra‐class correlation coefficient (ICC) and Bland–Altman (BA) analysis. False discovery rate (FDR) method was applied for multiple comparisons correction. Results: ADCuh values in the bilateral thalamus, caudate nucleus, putamen, and globus pallidus in MRI‐negative drug‐resistant epilepsy were significantly higher than those in the healthy control subjects (all p < 0.05, FDR corrected). Significance: The alterations of the ADCuh values in the bilateral thalamus and striatum in MRI‐negative drug‐resistant epilepsy might reflect abnormal membrane water permeability in MRI‐negative drug‐resistant epilepsy. ADCuh might be a sensitive measurement for evaluating subcortical nuclei‐related brain damage in epilepsy patients. Plain Language Summary: This study aimed to explore the alterations of apparent diffusion coefficient calculated from ultra high b‐values (ADCuh) in the subcortical nuclei such as the bilateral thalamus and striatum in MRI‐negative drug‐resistant epilepsy. The bilateral thalamus and striatum showed higher ADCuh in epilepsy patients than healthy controls. These findings may add new evidences of subcortical nuclei abnormalities related to water and ion hemostasis in epilepsy patients, which might help to elucidate the underlying epileptic neuropathophysiological mechanisms and facilitate the exploration of therapeutic targets. [ABSTRACT FROM AUTHOR]

BACKGROUND: This article aims to fit kinetic models of the passion fruit seed drying process, in addition to mathematical modeling using traditional models and fractional calculus of the extraction of lipids from the seeds. RESULTS: Regarding the drying process, it was found that the model that best suited the two drying temperatures employed was the fractional order one. CONCLUSION: Analysis showed that for both drying conditions the value of parameter α was greater than 1, indicating that the profile that occurs for the seeds is superdiffusion. Regarding the mathematical fits of oil extraction, it was found that the two models that presented the best fits for the lipid extraction kinetics were hyperbolic and fractional order. Regarding the fractional order model, as the value of parameter α was lower than 1, it can be seen that the process again does not follow Fick's law, and in this case a subdiffusion process occurs. © 2024 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

Cryo‐electron microscopy (cryo‐EM) has transformed structural biology over the past 12 years, with it now being routine rather than exceptional to reach a near‐atomic level of resolution for proteins and macromolecular complexes. Samples are immobilized by vitrification and this sample can be maintained at liquid nitrogen temperatures in the vacuum of the electron microscope with negligible sublimation. Due to the low electron doses needed to avoid radiation damage, averaging over tens of thousands to hundreds of thousands of particle images is used to achieve a high signal‐to‐noise ratio. An alternative approach has been proposed where samples are at room temperature in the liquid state, maintained in the vacuum of the electron microscope by thin film enclosures that are relatively transparent to electrons while preventing evaporation of the liquid. A paper has argued that using this liquid‐phase approach, higher resolution (3.2 Å) can be achieved than using cryo‐EM (3.4 Å) when imaging and reconstructing adeno‐associated virus particles. I show here that these assertions are untrue, and that basic principles in mathematics and physics would need to be violated to achieve the stated resolution in the liquid state. Thus, high resolution liquid phase EM of macromolecules remains science fiction. [ABSTRACT FROM AUTHOR]

In this work, a particle‐resolved computational fluid dynamics model of the acetylene hydrogenation process is developed to investigate the effects of catalyst particle structures on the reaction–diffusion behaviors aiming to improve selectivity toward target ethylene. The effects of packing structures on mass and heat transfer are explored by employing particles with varying shapes, wall thicknesses, and external diameters. The simulation results reveal that decreasing diffusion paths and elevating reactor bed temperature will enhance ethylene selectivity, and cylinder and Raschig ring packing structures exhibit the lowest and highest ethylene selectivity of 35.6% and 48.9% at 70% of acetylene conversion, respectively. Reducing wall thicknesses of Raschig ring particles facilitates the diffusion of generated ethylene from the interior zone of catalysts but concurrently inhibits the conversion of acetylene to ethylene. The Raschig ring catalyst particle with 1.9 mm of wall thickness and 3.5 mm of external diameter is finally revealed to exhibit the highest ethylene selectivity. [ABSTRACT FROM AUTHOR]

The coupling between energy‐consuming molecular processes and the macroscopic dimension plays an important role in nature and in the development of active matter. Here, we study the temporal evolution of a macroscopic system upon the local activation of a dissipative self‐assembly process. Injection of surfactant molecules in a substrate‐containing hydrogel results in the local substrate‐templated formation of assemblies, which are catalysts for the conversion of substrate into waste. We show that the system develops into a macroscopic (pseudo‐)non‐equilibrium steady state (NESS) characterized by the local presence of energy‐dissipating assemblies and persistent substrate and waste concentration gradients. For elevated substrate concentrations, this state can be maintained for more than 4 days. The studies reveal an interdependence between the dissipative assemblies and the concentration gradients: catalytic activity by the assemblies results in sustained concentration gradients and, vice versa, continuous diffusion of substrate to the assemblies stabilizes their size. The possibility to activate dissipative processes with spatial control and create long lasting non‐equilibrium steady states enables dissipative structures to be studied in the space‐time domain, which is of relevance for understanding biological systems and for the development of active matter. [ABSTRACT FROM AUTHOR]

Interactions at high temperatures between thin films and the Si substrate limit materials discovery using combinatorial processing platforms (CPPs). To overcome this, a diffusion and reaction barrier, SiO2, by thermal oxidation of Si tips is developed. The application of this diffusion barrier in CPPs for atomic‐scale investigations of new materials in atom probe tomography is reported. Thermal SiO2 layers (20 and 50 nm thick) are examined as barriers to separate coatings from Si tips. Pt is chosen as it easily forms silicides. CPPs are sequentially annealed in vacuum at 400 °C for 10 h, 600 °C for 2 h, and 800 °C for 2 h. The thermal SiO2 diffusion barrier remains stable and prevents intermixing at least up to 800 °C. Moreover, it provides improved film adhesion as dewetting of Pt on the oxide surface occurred at 800 °C instead of 600 °C without a thermal diffusion barrier. A comprehensive structural and chemical analysis of the Pt film, the thermal SiO2 layer, and their interfaces is performed using scanning and transmission electron microscopy, and atom probe tomography. As a result, the thermal SiO2 forms a stable barrier, even at the lowest thickness of 20 nm, avoiding the formation of Pt silicides, even at 800 °C. [ABSTRACT FROM AUTHOR]

Rechargeable multivalent‐ion batteries are attractive alternatives to Li‐ion batteries to mitigate their issues with metal resources and metal anodes. However, many challenges remain before they can be practically used due to the low solid‐state mobility of multivalent ions. In this study, a promising material identified by high‐throughput computational screening is investigated, ε‐VOPO4, as a Mg cathode. The experimental and computational evaluation of ε‐VOPO4 suggests that it may provide an energy density of >200 Wh kg−1 based on the average voltage of a complete cycle, significantly more than that of well‐known Chevrel compounds. Furthermore, this study finds that Mg‐ion diffusion can be enhanced by co‐intercalation of Li or Na, pointing at interesting correlation dynamics of slow and fast ions. [ABSTRACT FROM AUTHOR]