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Purpose: This work reports for the first time on the implementation and application of cardiac diffusion‐weighted MRI on a Connectom MR scanner with a maximum gradient strength of 300 mT/m. It evaluates the benefits of the increased gradient performance for the investigation of the myocardial microstructure. Methods: Cardiac diffusion‐weighted imaging (DWI) experiments were performed on 10 healthy volunteers using a spin‐echo sequence with up to second‐ and third‐order motion compensation (M2$$ {M}_2 $$ and M3$$ {M}_3 $$) and b=100, 450$$ b=100,450 $$, and 1000 s/mm2$$ \mathrm{s}/\mathrm{m}{\mathrm{m}}^2 $$ (twice the bmax$$ {b}_{\mathrm{max}} $$ commonly used on clinical scanners). Mean diffusivity (MD), fractional anisotropy (FA), helix angle (HA), and secondary eigenvector angle (E2A) were calculated for b = [100, 450] s/mm2$$ \mathrm{s}/\mathrm{m}{\mathrm{m}}^2 $$ and b = [100, 1000] s/mm2$$ \mathrm{s}/\mathrm{m}{\mathrm{m}}^2 $$ for both M2$$ {M}_2 $$ and M3$$ {M}_3 $$. Results: The MD values with M3$$ {M}_3 $$ are slightly higher than with M2$$ {M}_2 $$ with ΔMD=0.05±0.05[×10−3mm2/s](p=4e−5)$$ \Delta \mathrm{MD}=0.05\pm 0.05\kern0.3em \left[\times 1{0}^{-3}\kern0.3em {\mathrm{mm}}^2/\mathrm{s}\right]\kern0.3em \left(p=4e-5\right) $$ for bmax=450s/mm2$$ {b}_{\mathrm{max}}=450\kern0.3em \mathrm{s}/{\mathrm{mm}}^2 $$ and ΔMD=0.03±0.03[×10−3mm2/s](p=4e−4)$$ \Delta \mathrm{MD}=0.03\pm 0.03\kern0.3em \left[\times \kern0.3em 1{0}^{-3}\kern0.3em {\mathrm{mm}}^2/\mathrm{s}\right]\kern0.3em \left(p=4e-4\right) $$ for bmax=1000s/mm2$$ {b}_{\mathrm{max}}=1000\kern0.3em \mathrm{s}/{\mathrm{mm}}^2 $$. A reduction in MD is observed by increasing the bmax$$ {b}_{\mathrm{max}} $$ from 450 to 1000 s/mm2$$ \mathrm{s}/{\mathrm{mm}}^2 $$ (ΔMD=0.06±0.04[×10−3mm2/s](p=1.6e−9)$$ \Delta \mathrm{MD}=0.06\pm 0.04\kern0.3em \left[\times \kern0.3em 1{0}^{-3}\kern0.3em {\mathrm{mm}}^2/\mathrm{s}\right]\kern0.3em \left(p=1.6e-9\right) $$ for M2$$ {M}_2 $$ and ΔMD=0.08±0.05[×10−3mm2/s](p=1e−9)$$ \Delta \mathrm{MD}=0.08\pm 0.05\kern0.3em \left[\times \kern0.3em 1{0}^{-3}\kern0.3em {\mathrm{mm}}^2/\mathrm{s}\right]\kern0.3em \left(p=1e-9\right) $$ for M3$$ {M}_3 $$). The difference between FA, E2A, and HA was not significant in different schemes (p>0.05$$ p>0.05 $$). Conclusion: This work demonstrates cardiac DWI in vivo with higher b‐value and higher order of motion compensated diffusion gradient waveforms than is commonly used. Increasing the motion compensation order from M2$$ {M}_2 $$ to M3$$ {M}_3 $$ and the maximum b‐value from 450 to 1000 s/mm2$$ \mathrm{s}/{\mathrm{mm}}^2 $$ affected the MD values but FA and the angular metrics (HA and E2A) remained unchanged. Our work paves the way for cardiac DWI on the next‐generation MR scanners with high‐performance gradient systems. [ABSTRACT FROM AUTHOR]

Background and Aims: The prevalence of carbapenemase‐producing Enterobacterales (CPE) continues to increase worldwide. Combination of β‐lactam and novel β‐lactamase inhibitors introduce a revolutionary treatment option for CPE. Ceftazidime/avibactam (CAZ/AVB) has been recently developed for treatment of severe infections caused by multidrug‐resistant bacteria. We aimed to evaluate in vitro activity of CAZ/AVB on a collection of 85 ESBL‐producing‐carbapenemase negative and CPE from Iran. Methods: ESBL and carbapenemase production was phenotypically confirmed by combined disk test and modified carbapenem inactivation method respectively. The presence of clinically important carbapenemase encoding genes was examined using PCR. Susceptibility of all isolates to CAZ/AVB was determined using discs containing 30 μg ceftazidime +20 μg avibactam (AVB). Minimum inhibitory concentrations (MICs) of CAZ/AVB in 28 CPE (4 Escherichia coli and 24 Klebsiella pneumoniae) was determined by gradient diffusion method using MIC test strips (0.016−256 mg/L ceftazidime +4 mg/L AVB). Results: All phenotypically identified ESBL positive‐carbapenemase negative isolates were found to be susceptible to CAZ/AVB. Among the carbapenem resistant isolates, CAZ/AVB showed potent inhibitory activity against all OXA‐48‐like (MIC ranges 0.125/4−0.75/4 mg/L) and KPC positive isolates (MIC ranges <0.016/4−0.19/4 mg/L). However, AVB could not restore the activity of ceftazdime against isolates producing metallo‐β‐lactamases (MLBs) including VIM, NDM (MIC > 256/4 mg/L) and IMP (MIC > 8/4 mg/L). Conclusion: Our data highlighted the excellent in vitro performance of CAZ/AVB against ESBL‐producing and CPE suggesting that this combination can efficiently be used as therapeutic option for management of CPE infections particularly in regions with high prevalence of KPC and/or OXA‐48‐like positive but MBL‐negative Enterobacterales. [ABSTRACT FROM AUTHOR]

Purpose: Diffusion‐weighted (DW) imaging provides a useful clinical contrast, but is susceptible to motion‐induced dephasing caused by the application of strong diffusion gradients. Phase navigators are commonly used to resolve shot‐to‐shot motion‐induced phase in multishot reconstructions, but poor phase estimates result in signal dropout and Apparent Diffusion Coefficient (ADC) overestimation. These artifacts are prominent in the abdomen, a region prone to involuntary cardiac and respiratory motion. To improve the robustness of DW imaging in the abdomen, region‐based shot rejection schemes that selectively weight regions where the shot‐to‐shot phase is poorly estimated were evaluated. Methods: Spatially varying weights for each shot, reflecting both the accuracy of the estimated phase and the degree of subvoxel dephasing, were estimated from the phase navigator magnitude images. The weighting was integrated into a multishot reconstruction using different formulations and phase navigator resolutions and tested with different phase navigator resolutions in multishot DW‐echo Planar Imaging acquisitions of the liver and pancreas, using conventional monopolar and velocity‐compensated diffusion encoding. Reconstructed images and ADC estimates were compared qualitatively. Results: The proposed region‐based shot rejection reduces banding and signal dropout artifacts caused by physiological motion in the liver and pancreas. Shot rejection allows conventional monopolar diffusion encoding to achieve median ADCs in the pancreas comparable to motion‐compensated diffusion encoding, albeit with a greater spread of ADCs. Conclusion: Region‐based shot rejection is a linear reconstruction that improves the motion robustness of multi‐shot DWI and requires no sequence modifications. [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: Magnetic resonance diffusion tensor imaging (DTI) has recently been used to evaluate the developing cartilage of children, but the influencing factors have not been well studied. Objective: The objective of this study was to investigate the influence of the diffusion gradient strength (b value), diffusion gradient direction, age and sex on knee cartilage DTI in healthy children aged 6–12 years. Materials and methods: A total of 30 healthy child volunteers, with an average age of 8.9 ± 1.6 (mean ± standard deviation) years, were enrolled in this study. They were categorized into three groups according to their age range: 6–8 years, 8–10 years and 10–12 years, ensuring equal sex distribution in each group (5 boys and 5 girls). These volunteers underwent routine left knee joint magnetic resonance imaging (MRI) and serial DTI scans. DTI parameters were altered as follows: when b value = 600 s/mm2, diffusion gradient direction was set to 6, 15, 25, 35 and 45; and when diffusion gradient direction = 25, b value was set to 300, 600, 900 and 1200 s/mm2. The values of fractional anisotropy (FA) and apparent diffusion coefficient (ADC) were separately acquired using image post-processing techniques. The correlation between various b values, diffusion gradient directions, age and sex on the one hand and FA and ADC values on the other, was investigated. Results: (1) When diffusion gradient direction was fixed and the b value was varied, both FA and ADC exhibited a decreasing trend as the b value increased (P < 0.001). (2) When the b value was fixed and diffusion gradient direction was varied, the FA of knee cartilage showed a decreasing trend with increasing diffusion gradient direction (P < 0.001). (3) The FA value increased with age (P < 0.05). Conclusion: The b value, diffusion gradient direction value and age exert a significant impact on both FA and ADC values in MR DTI of knee cartilage in children aged 6–12 years. In order to obtain a stable DTI, it is recommended to select a b value ≥ 600 s/mm2 and a diffusion gradient direction ≥ 25 during scanning. [ABSTRACT FROM AUTHOR]

Background The glycopeptide vancomycin is the antimicrobial agent-of-choice for the treatment of severe non-gastrointestinal infections with members of Bacillus cereus sensu lato (s.l.). Recently, sporadic detection of vancomycin-resistant phenotypes emerged, mostly for agar diffusion testing such as the disc diffusion method or gradient test (e.g. Etest®) method. Results In this work, we were able to disprove a preliminarily assumed high resistance to vancomycin in an isolate of B. cereus s.l. using broth microdilution and agar dilution. Microscopic imaging during vancomycin susceptibility testing showed spreading towards the inhibition zone, which strongly suggested sliding motility. Furthermore, transcriptomic analysis using RNA-Seq on the nanopore platform revealed several key genes of biofilm formation (e.g. calY , tasA , krsEABC) to be up-regulated in pseudo-resistant cells, substantiating that bacterial sliding is responsible for the observed mobility. Down-regulation of virulence (e.g. hblABCD , nheABC , plcR) and flagellar genes compared with swarming cells also confirmed the non-swarming phenotype of the pseudo-resistant isolate. Conclusions The results highlight an insufficiency of agar diffusion testing for vancomycin susceptibility in the B. cereus group, and reference methods like broth microdilution are strongly recommended. As currently no guideline mentions interfering phenotypes in antimicrobial susceptibility testing of B. cereus s.l. , this knowledge is essential to obtain reliable results on vancomycin susceptibility. In addition, this is the first report of sliding motility undermining accurate antimicrobial susceptibility testing in B. cereus s.l. and may serve as a basis for future studies on bacterial motility in susceptibility testing and its potential impact on treatment efficacy. [ABSTRACT FROM AUTHOR]

We investigate crystallization-driven convection in carbon–oxygen white dwarfs. We present a version of the mixing length theory that self-consistently includes the effects of thermal diffusion and composition gradients, and provides solutions for the convective parameters based on the local heat and composition fluxes. Our formulation smoothly transitions between the regimes of fast adiabatic convection at large Peclet number and slow thermohaline convection at low Peclet number. It also allows for both thermally driven and compositionally driven convection, including correctly accounting for the direction of heat transport for compositionally driven convection in a thermally stable background. We use the MESA stellar evolution code to calculate the composition and heat fluxes during crystallization in different models of cooling white dwarfs, and determine the regime of convection and the convective velocity. We find that convection occurs in the regime of slow thermohaline convection during most of the cooling history of the star. However, at the onset of crystallization, the composition flux is large enough to drive fast overturning convection for a short time (∼10 Myr). We estimate the convective velocities in both of these phases and discuss the implications for explaining observed white dwarf magnetic fields with crystallization-driven dynamos. [ABSTRACT FROM AUTHOR]

Diffusion weighted imaging (DWI) with optimized motion-compensated gradient waveforms reduces signal dropouts in the liver and pancreas caused by cardiovascular-associated motion, however its precision is unknown. We hypothesized that DWI with motion-compensated DW gradient waveforms would improve apparent diffusion coefficient (ADC)-repeatability and inter-reader reproducibility compared to conventional DWI in these organs. In this IRB-approved, prospective, single center study, subjects recruited between October 2019 and March 2020 were scanned twice on a 3 T scanner, with repositioning between test and retest. Each scan included two respiratory-triggered DWI series with comparable acquisition time: 1) conventional (monopolar) 2) motion- compensated diffusion gradients. Three readers measured ADC values. One-way ANOVA, Bland-Altman analysis were used for statistical analysis. Eight healthy participants (4 male/4 female), with a mean age of 29 ± 4 years, underwent the liver and pancreas MRI protocol. Four patients with liver metastases (2 male/2 female) with a mean age of 58 ± 5 years underwent the liver MRI protocol. In healthy participants, motion-compensated DWI outperformed conventional DWI with mean repeatability coefficient of 0.14 × 10−3 (CI:0.12–0.17) vs. 0.31 × 10−3 (CI:0.27–0.37) mm2/s for liver, and 0.11 × 10−3 (CI:0.08–0.15) vs. 0.34 × 10−3 (CI:0.27–0.49) mm2/s for pancreas; and with mean reproducibility coefficient of 0.20 × 10−3 (CI:0.18–0.23) vs. 0.51 × 10−3 (CI:0.46–0.58) mm2/s for liver, and 0.16 × 10−3 (CI:0.13–0.20) vs. 0.42 × 10−3 (CI:0.34–0.52) mm2/s for pancreas. In patients, improved repeatability was observed for motion-compensated DWI in comparison to conventional with repeatability coefficient of 0.51 × 10− 3 mm2/s (CI:0.35–0.89) vs. 0.70 × 10−3 mm2/s (CI:0.49–1.20). Motion-compensated DWI enhances the precision of ADC measurements in the liver and pancreas compared to conventional DWI. [ABSTRACT FROM AUTHOR]

Large skin injuries heal as scars. Stiffness gradually increases from normal skin to scar tissue (20x higher), due to excessive deposition and crosslinking of extracellular matrix (ECM) mostly produced by (myo)fibroblasts. Using a custom mold, skin-derived ECM hydrogels (dECM) were UV crosslinked after diffusion of ruthenium (Ru) to produce a Ru-dECM gradient hydrogel. The Ru diffusion gradient equates to a stiffness gradient and models physiology of the scarred skin. Crosslinking in Ru-dECM hydrogels results in a 23-fold increase in stiffness from a stiffness similar to that of normal skin. Collagen fiber density increases in a stiffness-dependent fashion while stress relaxation also alters, with one additional Maxwell element necessary for characterizing Ru-dECM. Alignment of fibroblasts encapsulated in hydrogels suggests that the stiffness gradient directs fibroblasts to orientate at ∼45 ° in regions below 120 kPa. In areas above 120 kPa, fibroblasts decrease the stiffness prior to adjusting their orientation. Furthermore, fibroblasts remodel their surrounding ECM in a gradient-dependent fashion, with rearrangement of cell-surrounding ECM in high-stiffness areas, and formation of interlaced collagen bundles in low-stiffness areas. Overall, this study shows that fibroblasts remodel their local environment to generate an optimal ECM mechanical and topographical environment. This study developed a versatile in vitro model with a gradient stiffness using skin-derived ECM hydrogel with unchanged biochemical environment. Using Ruthenium crosslinking, a 20-fold stiffness increase was achieved as observed in fibrotic skin. The interaction between fibroblasts and matrix depends on changes in the matrix stiffness. The stiffness gradient directed the alignment of fibroblasts with ∼45° in regions with≤ 120 kPa. The cells in regions with the higher stiffness decreased stiffness first and then oriented themselves. Furthermore, fibroblasts remodeled surrounding ECM and regulated its mechanics in a gradient-dependent fashion to reach an optimal condition. Our study highlights the dynamic interplay between cells and surrounding matrix, shedding light on potential mechanisms and strategies to target scar formation and remodeling. [Display omitted] [ABSTRACT FROM AUTHOR]

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Purpose: Joint analysis of flow‐compensated (FC) and non‐flow‐compensated (NC) diffusion MRI (dMRI) data has been suggested for increased robustness of intravoxel incoherent motion (IVIM) parameter estimation. For this purpose, a set of methods commonly used or previously found useful for IVIM analysis of dMRI data obtained with conventional diffusion encoding were evaluated in healthy human brain. Methods: Five methods for joint IVIM analysis of FC and NC dMRI data were compared: (1) direct non‐linear least squares fitting, (2) a segmented fitting algorithm with estimation of the diffusion coefficient from higher b‐values of NC data, (3) a Bayesian algorithm with uniform prior distributions, (4) a Bayesian algorithm with spatial prior distributions, and (5) a deep learning‐based algorithm. Methods were evaluated on brain dMRI data from healthy subjects and simulated data at multiple noise levels. Bipolar diffusion encoding gradients were used with b‐values 0–200 s/mm2 and corresponding flow weighting factors 0–2.35 s/mm for NC data and by design 0 for FC data. Data were acquired twice for repeatability analysis. Results: Measurement repeatability as well as estimation bias and variability were at similar levels or better with the Bayesian algorithm with spatial prior distributions and the deep learning‐based algorithm for IVIM parameters D$$ D $$ and f$$ f $$, and for the Bayesian algorithm only for vd$$ {v}_d $$, relative to the other methods. Conclusion: A Bayesian algorithm with spatial prior distributions is preferable for joint IVIM analysis of FC and NC dMRI data in the healthy human brain, but deep learning‐based algorithms appear promising. [ABSTRACT FROM AUTHOR]

Assays mimicking in vitro the concentration gradients triggering biological responses like those involved in fighting infections and blood clotting are essential for biomedical research. Microfluidic assays prove especially attractive as they allow precise control of gradient shape allied to a reduction in scale. Conventional microfluidic devices are fabricated using solid plastics that prevent direct access to responding cells. Fluid-walled microfluidics allows the manufacture of circuits on standard Petri dishes in seconds, coupled to simple operating methods; cell-culture medium sitting in a standard dish is confined to circuits by fluid walls made of an immiscible fluorocarbon. We develop and experimentally validate an analytical model of diffusion between two or more aqueous streams flowing at different rates into a fluid-walled conduit with the cross-section of a circular segment. Unlike solid walls, fluid walls morph during flows as pressures fall, with wall shape changing down the conduit. The model is validated experimentally for Fourier numbers < 0.1 using fluorescein diffusing between laminar streams. It enables a priori prediction of concentration gradients throughout a conduit, so allowing rapid circuit design as well as providing bio-scientists with an accurate way of predicting local concentrations of bioactive molecules around responsive and non-responsive cells. [ABSTRACT FROM AUTHOR]

Purpose: This study aims to evaluate two distinct approaches for fiber radius estimation using diffusion-relaxation MRI data acquired in biomimetic microfiber phantoms that mimic hollow axons. The methods considered are the spherical mean power-law approach and a T2-based pore size estimation technique. Theory and Methods: A general diffusion-relaxation theoretical model for the spherical mean signal from water molecules within a distribution of cylinders with varying radii was introduced, encompassing the evaluated models as particular cases. Additionally, a new numerical approach was presented for estimating effective radii (i.e., MRI-visible mean radii) from the ground truth radii distributions, not reliant on previous theoretical approximations and adaptable to various acquisition sequences. The ground truth radii were obtained from scanning electron microscope images. Results: Both methods show a linear relationship between effective radii estimated from MRI data and ground-truth radii distributions, although some discrepancies were observed. The spherical mean power-law method overestimated fiber radii. Conversely, the T2-based method exhibited higher sensitivity to smaller fiber radii, but faced limitations in accurately estimating the radius in one particular phantom, possibly because of material-specific relaxation changes. Conclusion: The study demonstrates the feasibility of both techniques to predict pore sizes of hollow microfibers. The T2-based technique, unlike the spherical mean power-law method, does not demand ultra-high diffusion gradients, but requires calibration with known radius distributions. This research contributes to the ongoing development and evaluation of neuroimaging techniques for fiber radius estimation, highlights the advantages and limitations of both methods, and provides datasets for reproducible research. [ABSTRACT FROM AUTHOR]

The efficiency of iron/aluminum co-modified zeolite (FeAl-Z) covering and amendment for controlling the internal loading of phosphorus (P) from sediment to the overlying water (OW) and its controlling mechanism were explored. The response of the composition of sedimentary microbial communities in sediment and their function to the FeAl-Z capping and amendment was also examined. FeAl-Z showed good removal performance for phosphate in aqueous solution. The maximum phosphate adsorption quantity for FeAl-Z at pH 7 attained 11.2 mg P/g. The release of sediment endogenous phosphorus to OW can be successfully restrained by the FeAl-Z covering and amendment, and the suppression ability of FeAl-Z covering was stronger than that of FeAl-Z amendment. Under the capping or amendment condition, FeAl-Z can effectively inactivate the labile phosphorus measured by diffusion gradient in thin film (DGT-LP) in the overlying water and surface sediment. The added FeAl-Z transformed redox-sensitive phosphorus (BD-P) to metal oxide-bound phosphorus (NaOH-IP) and residual phosphorus (Res-P) in sediment, which increased the stability of inorganic phosphorus in the sediment. The passivation of soluble reactive phosphorus (SRP) and DGT-LP in the surface sediment by FeAl-Z significantly contributed to the inhibition of sediment endogenous phosphorus release to OW by the FeAl-Z capping, and the passivation of SRP, DGT-LP and mobile phosphorus in the surface sediment played a pivotal role in the control of sediment internal phosphorus release by the FeAl-Z amendment. The FeAl-Z amendment and capping did not increase the liberation risk of Fe from sediment, and the microorganisms in the sediments under the conditions of FeAl-Z amendment and covering still can perform good ecological functions. Results of this research demonstrate that FeAl-Z capping has high application potential in the control of phosphorus transfer from sediment to OW. [ABSTRACT FROM AUTHOR]

BACKGROUND: Diffusion-weighted imaging (DWI) is a noninvasive method used for investigating the microstructural properties of the brain. However, a tradeoff exists between resolution and scanning time in clinical practice. Super-resolution has been employed to enhance spatial resolution in natural images, but its application on high-dimensional and non-Euclidean DWI remains challenging. OBJECTIVE: This study aimed to develop an end-to-end deep learning network for enhancing the spatial resolution of DWI through post-processing. METHODS: We proposed a space-customized deep learning approach that leveraged convolutional neural networks (CNNs) for the grid structural domain (x-space) and graph CNNs (GCNNs) for the diffusion gradient domain (q-space). Moreover, we represented the output of CNN as a graph using correlations defined by a Gaussian kernel in q-space to bridge the gap between CNN and GCNN feature formats. RESULTS: Our model was evaluated on the Human Connectome Project, demonstrating the effective improvement of DWI quality using our proposed method. Extended experiments also highlighted its advantages in downstream tasks. CONCLUSION: The hybrid convolutional neural network exhibited distinct advantages in enhancing the spatial resolution of DWI scans for the feature learning of heterogeneous spatial data. [ABSTRACT FROM AUTHOR]

Antimicrobial resistance in Neisseria gonorrhoeae (NG) is increasing worldwide. Second-line treatments with macrolides or fluoroquinolones are an option for NG infections in some cases following the STI guideline recommendations. In our study, we compared the gradient diffusion test using EUCAST 2024 breakpoints with a new molecular method using the Allplex™ NG&DR assay (Seegene®) including A2059G/C2611 mutations (23S rRNA) associated with high/moderate-level macrolide resistance and S91F mutation (gyrA) relationship with fluoroquinolone resistance in NG isolates (n = 100). We calculated the sensitivity, specificity, and correlation of the molecular test for fluoroquinolone using the gradient diffusion as the reference method. In twenty-three strains was not detected any mutation associated with macrolides or fluoroquinolone resistance. No A2059G/C2611T mutations were detected, and the S91F mutations were detected in 77 out of the 100 isolates screened. Twenty-three NG isolates were reported to be resistant to azithromycin (ECOFF: >1 mg/L), and 78 NG isolates were resistant to ciprofloxacin (MIC: >0.06 mg/L). The molecular method showed a sensitivity of 96.1% and, a specificity of 90.9% for fluoroquinolone susceptibility, but the statistical analysis between the molecular test and gradient diffusion test was not statistically significant for fluoroquinolone resistance (p = 1). Statistical analysis was not performed for macrolides because of the absence of positive RT-PCR results. According to our data, Allplex™ assay cannot replace the gradient diffusion test for macrolide resistance. However, the assay could be used to test fluoroquinolone resistance in NG isolates as a replacement for phenotypic methods. [ABSTRACT FROM AUTHOR]

We describe a compact finite-difference discretization and Gaussian-radial basis function for the two-dimensional local fractional elliptic PDEs that describe anomalous diffusion-convection of groundwater contamination. Precisely estimating pollutant concentration over a long period helps protect water reservoirs. The local fractional partial differential equations and their discretization described here are the generalization of the integer order elliptic partial differential equations and their high-order scheme. The high-order discretization of fractal gradient and anomalous diffusion on a non-uniformly spaced nine-point single-cell grid network gives the result in small computing time. The new scheme is supported by a detailed convergence analysis describing the monotone property and a strongly connected Jacobian (iteration) matrix graph. The computational illustration of various anomalous diffusion-convection models demonstrates the proposed methodology's effectiveness. [ABSTRACT FROM AUTHOR]

Introduction: Carbapenem-resistant gram-negative bacilli are a worldwide concern because of high morbidity and mortality rates. Additionally, the increasing prevalence of these bacteria is dangerous. To investigate the extent of antimicrobial resistance and prioritize the utility of novel drugs, we evaluated the molecular characteristics and antimicrobial susceptibility profiles of carbapenem-resistant Enterobacterales, Pseudomonas aeruginosa and Acinetobacter baumannii in Ecuador in 2022. Methods: Ninety-five clinical isolates of carbapenem non-susceptible gram-negative bacilli were collected from six hospitals in Ecuador. Carbapenem resistance was confirmed with meropenem disk diffusion assays following Clinical Laboratory Standard Institute guidelines. Carbapenemase production was tested using a modified carbapenemase inactivation method. Antimicrobial susceptibility was tested with a disk diffusion assay, the Vitek 2 System, and gradient diffusion strips. Broth microdilution assays were used to assess colistin susceptibility. All the isolates were screened for the blaKPC,blaNDM,blaOXA-48,blaVIM and blaIMP genes. In addition, A. baumannii isolates were screened for the blaOXA-23, blaOXA-58 and blaOXA-24/40 genes. Results: Carbapenemase production was observed in 96.84% of the isolates. The blaKPC, blaNDM and blaOXA-48 genes were detected in Enterobacterales, with blaKPC being predominant. The blaVIM gene was detected in P. aeruginosa, and blaOXA-24/40 predominated in A. baumannii. Most of the isolates showed co-resistance to aminoglycosides, fluoroquinolones, and trimethoprim/sulfamethoxazole. Both ceftazidime/avibactam and meropenem/vaborbactam were active against carbapenem-resistant gram-negative bacilli that produce serin-carbapenemases. Conclusion: The epidemiology of carbapenem resistance in Ecuador is dominated by carbapenemase-producing K. pneumoniae harbouring blaKPC. Extensively drug resistant (XDR) P. aeruginosa and A. baumannii were identified, and their identification revealed the urgent need to implement strategies to reduce the dissemination of these strains. [ABSTRACT FROM AUTHOR]

Purpose: The characterization of tissue microstructure using diffusion MRI (dMRI) signals is rapidly evolving, with increasing sophistication of signal representations and microstructure models. However, this progress often requires signals to be acquired with very high b‐values (e.g., b > 30 ms/μm2), along many directions, and using multiple b‐values, leading to long scan times and extremely low SNR in dMRI images. The purpose of this work is to boost the SNR efficiency of dMRI by combining three particularly efficient spatial encoding techniques and utilizing a high‐performance gradient system (Gmax ≤ 300 mT/m) for efficient diffusion encoding. Methods: Spiral readouts, multiband imaging, and sampling on tilted hexagonal grids (T‐Hex) are combined and implemented on a 3T MRI system with ultra‐strong gradients. Image reconstruction is performed through an iterative cg‐SENSE algorithm incorporating static off‐resonance distributions and field dynamics as measured with an NMR field camera. Additionally, T‐Hex multiband is combined with a more conventional EPI‐readout and compared with state‐of‐the‐art blipped‐CAIPIRINHA sampling. The advantage of the proposed approach is furthermore investigated for clinically available gradient performance and diffusion kurtosis imaging. Results: High fidelity in vivo images with b‐values up to 40 ms/μm2 are obtained. The approach provides superior SNR efficiency over other state‐of‐the‐art multiband diffusion readout schemes. Conclusion: The demonstrated gains hold promise for the widespread dissemination of advanced microstructural scans, especially in clinical populations. [ABSTRACT FROM AUTHOR]

Purpose: To demonstrate the feasibility of motion compensating diffusion gradient schemes in the acquisition of quality diffusion tensor images (DTI) of the brain during continuous gross head motion. Methods: Five healthy subjects were scanned using a clinical 3 T MRI with and without continuous head motion. For one volunteer, DTI data was acquired using standard (M0) diffusion‐weighted (DW) gradients, and first (M1) and second (M2) order gradient schemes that were previously developed for use in cardiac DTI. In four additional volunteers, DTI data was acquired with M0 and M2 gradients. DTI parameters were calculated and compared with established retrospective motion corrections. Results: In the absence of motion, DTI parameters calculated from M0, M1, and M2 data were consistent. In the presence of motion, up to 44% of DW images acquired with M0 gradients were corrupted by signal dropout, compared to 0% of the M2 images. In voxelwise comparisons, DTI parameters calculated using motion‐M0 data were elevated compared to reference data. Retrospective corrections for extreme motion applied to motion‐M0 data did not improve consistency with reference data in cases where motion corrupted >15% of DW images. In contrast, DTI parameters calculated with motion‐M2 data were consistent with reference data. Conclusion: This proof‐of‐principle study demonstrates that motion compensating diffusion gradients can mitigate artifacts because of continuous motion in DTI of the brain and offers promise for improved DTI accessibility. Further study will be necessary to determine the robustness of the approach in patient populations with high susceptibility to head motion. [ABSTRACT FROM AUTHOR]

(La0.2Yb0.2Sm0.2Eu0.2Gd0.2)2Zr2O7 (HEZ) has shown considerable promise as a novel thermal barrier coating material for temperatures exceeding 1300 °C. This study systematically investigates the interfacial stability of (La0.2Yb0.2Sm0.2Eu0.2Gd0.2)2Zr2O7 with yttria-stabilized zirconia (YSZ), which is of paramount importance for its application in double-layer thermal barrier coatings. Our findings highlight that rare earth elements with a smaller radius diffuse more easily into the YSZ lattice, resulting in a broader diffusion zone. Simultaneously, the incorporation of rare earth elements into the YSZ lattice inhibits tetragonal-to-monoclinic phase transformation. Compared to La2Zr2O7/YSZ, HEZ/YSZ demonstrates superior high-temperature stability, which could be attributed to the higher fracture toughness and lower thermal expansion coefficient of HEZ, the absence of t-m transformation and the formation of a continuous gradient diffusion layer that minimizes interface stress. This study offers a practical strategy for designing materials for durable double-layer thermal barrier coating systems. [ABSTRACT FROM AUTHOR]

Purpose: This study aims to develop a high‐efficiency and high‐resolution 3D imaging approach for simultaneous mapping of multiple key tissue parameters for routine brain imaging, including T1, T2, proton density (PD), ADC, and fractional anisotropy (FA). The proposed method is intended for pushing routine clinical brain imaging from weighted imaging to quantitative imaging and can also be particularly useful for diffusion‐relaxometry studies, which typically suffer from lengthy acquisition time. Methods: To address challenges associated with diffusion weighting, such as shot‐to‐shot phase variation and low SNR, we integrated several innovative data acquisition and reconstruction techniques. Specifically, we used M1‐compensated diffusion gradients, cardiac gating, and navigators to mitigate phase variations caused by cardiac motion. We also introduced a data‐driven pre‐pulse gradient to cancel out eddy currents induced by diffusion gradients. Additionally, to enhance image quality within a limited acquisition time, we proposed a data‐sharing joint reconstruction approach coupled with a corresponding sequence design. Results: The phantom and in vivo studies indicated that the T1 and T2 values measured by the proposed method are consistent with a conventional MR fingerprinting sequence and the diffusion results (including diffusivity, ADC, and FA) are consistent with the spin‐echo EPI DWI sequence. Conclusion: The proposed method can achieve whole‐brain T1, T2, diffusivity, ADC, and FA maps at 1‐mm isotropic resolution within 10 min, providing a powerful tool for investigating the microstructural properties of brain tissue, with potential applications in clinical and research settings. [ABSTRACT FROM AUTHOR]

Purpose: To investigate whether spatiotemporal magnetic field monitoring can correct pronounced eddy current‐induced artifacts incurred by strong diffusion‐sensitizing gradients up to 300 mT/m used in high b‐value diffusion‐weighted (DW) EPI. Methods: A dynamic field camera equipped with 16 1H NMR field probes was first used to characterize field perturbations caused by residual eddy currents from diffusion gradients waveforms in a 3D multi‐shot EPI sequence on a 3T Connectom scanner for different gradient strengths (up to 300 mT/m), diffusion directions, and shots. The efficacy of dynamic field monitoring‐based image reconstruction was demonstrated on high‐gradient strength, submillimeter resolution whole‐brain ex vivo diffusion MRI. A 3D multi‐shot image reconstruction framework was developed that incorporated the nonlinear phase evolution measured with the dynamic field camera. Results: Phase perturbations in the readout induced by residual eddy currents from strong diffusion gradients are highly nonlinear in space and time, vary among diffusion directions, and interfere significantly with the image encoding gradients, changing the k‐space trajectory. During the readout, phase modulations between odd and even EPI echoes become non‐static and diffusion encoding direction‐dependent. Superior reduction of ghosting and geometric distortion was achieved with dynamic field monitoring compared to ghosting reduction approaches such as navigator‐ and structured low‐rank‐based methods or MUSE followed by image‐based distortion correction with the FSL tool "eddy." Conclusion: Strong eddy current artifacts characteristic of high‐gradient strength DW‐EPI can be well corrected with dynamic field monitoring‐based image reconstruction. [ABSTRACT FROM AUTHOR]

Dragonfly nymphs breathe water using tidal ventilation, a highly unusual strategy in water-breathing animals owing to the high viscosity, density and low oxygen (O2) concentration of water. This study examines how well these insects extract O2 from the surrounding water during progressive hypoxia. Nymphs were attached to a custom-designed respiro-spirometer to simultaneously measure tidal volume, ventilation frequency and metabolic rate. Oxygen extraction efficiencies (OEE) were calculated across four partial pressure of oxygen (pO2) treatments, from normoxia to severe hypoxia. While there was no significant change in tidal volume, ventilation frequency increased significantly from 9.4 ± 1.2 breaths per minute (BPM) at 21.3 kPa to 35.6 ± 2.9 BPM at 5.3 kPa. Metabolic rate increased significantly from 1.4 ± 0.3 µl O2 min−1 at 21.3 kPa to 2.1 ± 0.4 µl O2 min−1 at 16.0 kPa, but then returned to normoxic levels as O2 levels declined further. OEE of nymphs was 40.1 ± 6.1% at 21.3 kPa, and did not change significantly during hypoxia. Comparison to literature shows that nymphs maintain their OEE during hypoxia unlike other aquatic tidal-breathers and some unidirectional breathers. This result, and numerical models simulating experimental conditions, indicate that nymphs maintain these extraction efficiencies by increasing gill conductance and/or lowering internal pO2 to maintain a sufficient diffusion gradient across their respiratory surface. [ABSTRACT FROM AUTHOR]

The gas diffusion layer (GDL) plays a vital role in water management of proton exchange membrane fuel cells. In this study, GDLs with nanoscale gradient pore sizes (nano-GDLs) are fabricated using electrospinning to explore the influence of the gradient layer number and degree of the pore size gradient on the water transport performance. The breakthrough pressure and water saturation tests indicate that nano-GDLs with uniform and gradient structures have higher breakthrough pressures and lower water saturation compared with those of the commercial Toray GDL, which facilitates back diffusion of water through the membrane and water discharge in the GDL. Specifically, among the nano-GDLs with a gradient structure, the three-layer medium-gradient nano-GDL sample (3-MG) possesses the maximum breakthrough pressure and minimum water saturation ratio. The fuel cell test determined that the maximum power density of the 3-MG nano-GDL sample is 14% higher than that with commercial Toray GDL without cathode humidification. • Electrospinning can fabricate gas diffusion layers with gradient pore sizes. • The nano-GDL pore size is much smaller than that of commercial Toray GDL. • The 3-MG nano-GDL has higher breakthrough pressure and lower water saturation. • The power density of 3-MG nano-GDL is 14% higher than commercial Toray GDL. [ABSTRACT FROM AUTHOR]

Water‐enabled electricity generation technologies that are highly accessible and fundamentally clean are promising for next‐generation green energy. However, the challenge of scalability in both material processing and device fabrication greatly limits their practical applications. A high‐performance polyelectrolyte moist‐electric generator (MEG), which can be directly 3D printed for massive production and efficient integration, is reported. The printed MEG (p‐MEG) generates a high open‐circuit voltage of 0.8 V and a short‐circuit‐current density of 0.12 mA cm−2 by actively harvesting moisture from humid conditions. The synergistic effects of moisture gradient, ionic concentration gradient, and ion diffusion gradient, which remarkably enhance the driving force to separate ion pairs and notably facilitate the directional ion transport, are responsible for the high power generation performance of p‐MEG, as further backed up by in situ ion dynamics investigations and molecular simulations. When connected in serial and parallel, hundreds of p‐MEGs can deliver a high voltage of more than 180 V and a current of more than 1 mA. A constructed "moisture‐powered cup lamp" that lights up for hours further demonstrates the practicability of p‐MEG. This work provides a feasible and scalable 3D printing approach for the next‐generation environment‐adaptive self‐powered system. [ABSTRACT FROM AUTHOR]

Diffusion-weighted double-echo steady-state (dwDESS) MRI with bipolar diffusion gradients is a promising candidate to obtain diffusion weighted images (DWI) free of geometric distortions and with low motion sensitivity. However, a wider clinical application of dwDESS is currently hindered as no method is reported to explicitly calculate the effective b-value of the obtained DWI from the diffusion-gradients applied in the sequence. To this end, a previously described signal model was adapted for dwDESS with bipolar diffusion gradients, which allows to estimate an effective b -value, dubbed b '. Evaluation in phantom examinations was performed on a clinical 1.5 T MR system. Experimental results were compared with theoretical predictions, including the apparent diffusion coefficient (ADC) based on b-values from a standard EPI-DWI sequence and ADC' based on the effective b ' from the dwDESS sequence. The adapted signal model was able to describe the experimental results, and the obtained values of ADC' were in line with conventional ADC measurements. [ABSTRACT FROM AUTHOR]

While internal aeration in plants is critical for adaptation to waterlogging, there is a gap in understanding the differences in oxygen diffusion gradients from shoots to roots between hypoxia-tolerant and -sensitive species. This study aims to elucidate the differences in tissue oxygen concentration at various locations on the shoot and root between a hypoxia-tolerant species and a -sensitive species using a microneedle sensor that allows for spatial oxygen profiling. Job's tears, a hypoxia-tolerant species, and sorghum, a hypoxia-susceptible species, were tested. Plants aged 10 days were acclimated to a hypoxic agar solution for 12 days. Oxygen was profiled near the root tip, root base, root shoot junction, stem, and leaf. An anatomical analysis was also performed on the roots used for the O2 profile. The oxygen partial pressure (pO2) values at the root base and tip of sorghum were significantly lower than that of the root of Job's tears. At the base of the root of Job's tears, pO2 rapidly decreased from the root cortex to the surface, indicating a function to inhibit oxygen leakage. No significant differences in pO2 between the species were identified in the shoot part. The root cortex to stele ratio was significantly higher from the root tip to the base in Job's tears compared to sorghum. The pO2 gradient began to differ greatly at the root shoot junction and root base longitudinally, and between the cortex and stele radially, between Job's tears and sorghum. Differences in the root oxygen retention capacity and the cortex to stele ratio are considered to be related to differences in pO2. [ABSTRACT FROM AUTHOR]

The utilization of the thin film gradient diffusion technique has been on the rise for appraising the efficacy of soil cadmium (Cd). Nonetheless, in contrast to conventional methodologies employed to gauge the efficacy of soil Cd, there exists a dearth of adequate research concerning whether the technique of diffusive gradients in thin films (DGT) can furnish a more precise and all-encompassing evaluation of soil Cd effectiveness in soil passivation and remediation procedures. Herein, this study selects four popular amendments (i.e. oyster shells, red mud, hydroxyapatite and biochar) and analyses the correlations among soil Cd availability, Cd uptake amount and spinach biomass. Results showed that the following concentration ranges: DGT-Cd (1.78-21.1 µg L-1), HAc-Cd (1.84-2.22 mg kg-1), DTPA-Cd (0.62-1.22 mg kg-1) and CaCl2-Cd (0.0489-0.103 mg kg-1). Among the methods, CaCl2 extraction had a lower capacity to extract soil Cd compared with the other methods. These amendments improved soil environment, promoted spinach growth and decreased plant Cd concentrations. Oyster shells and red mud treatments significantly reduced DGT-Cd levels (by 90.4% and 82.2%, respectively), which led to a reduction in plant Cd concentrations (by 77.1% and 72.4%) and bioconcentration factor (by 75.8% and 68.8%). Furthermore, oyster shells were found to be most effective in reducing soil-available Cd and inhibiting Cd uptake by spinach. Based on correlation analysis, the DGT method showed the largest measurement range and provided the best prediction of Cd accumulation in spinach compared with chemical extraction methods (R2 = .88, p <.001). Overall, the use of DGT in combination with plant uptake and chemical extraction data can provide a comprehensive assessment of soil Cd bioavailability. These findings facilitate an accurate and comprehensive evaluation of the bioavailability of Cd after applying amendments. These results also showed that oyster shells can be regarded as a promising eco-friendly and low-cost amendment for large-scale immobilizing Cd and producing plants with lesser Cd concentrations. [ABSTRACT FROM AUTHOR]

Introduction: Antimicrobial resistance is a growing problem that necessitates the development of new therapeutic options. Cefiderocol and aztreonam (AT) are often the last active β-lactams for treating metallo-β-lactamases (MBL)-producing Gram-negative bacilli. In these difficult-to-treat bacterial strains, AT resistance is frequently attributed to the co-occurrence of other resistance mechanisms. In the case of β-lactamases they can often be inhibited by avibactam. In the present study, we evaluated the use of the double-disc synergy test (DDST) as a screening tool for the detection of synergy between AT-avibactam (ATA). We validated both the Gradient Diffusion Strips (GDSs) superposition method and the commercially available Liofilchem’s ATA GDS. Materials and methods: We tested AT susceptibility in combination with ceftazidime-avibactam for 65 strains, including 18 Serine-β-Lactamase (SBL)- and 24 MBL-producing Enterobacterales, 12 MBL-producing P. aeruginosa, and 11 S. maltophilia isolates. Interpretation was done with EUCAST breakpoints (version 13.0), AT breakpoints being used for ATA. The accuracy and validity of the GDSs superposition method and ATA GDS were evaluated using an AT GDS applied on Mueller Hinton Agar plates supplemented with avibactam (MH-AV). A DDST was performed to screen for synergy between antibiotic combinations. Results: Using MH-AV, all SBL- and MBL-positive Enterobacterales were susceptible or susceptible at increased exposure to the combination AT-avibactam. In contrast, only 2 out of the 12 (17%) P. aeruginosa strains and 9/11 (82%) of the S. maltophilia strains were susceptible- or susceptible at increased exposure for the combination of AT-avibactam. The DDST detected all synergies, demonstrating a 100% sensitivity and 100% negative predictive value for all bacterial strains. Conclusion: The DDST is a sensitive tool for screening for antibiotic synergy. Unlike S. maltophilia and SBL- and MBL-positive Enterobacterales, most MBLpositive P. aeruginosa strains remain resistant to AT-avibactam. ATA GDS should be preferred for MIC determination of the AT-avibactam combination, while the GDSs superposition method can be used as an alternative to the commercial test. [ABSTRACT FROM AUTHOR]

Background and Aim: The agar dilution method is the approved method for determining the minimum inhibitory concentration (MIC) in fosfomycin susceptibility testing, whereas the broth dilution method is not recommended. This study aimed to investigate the potential of the gradient diffusion method as a more convenient alternative to agar dilution method for MIC evaluation, particularly for the susceptibility testing of Staphylococcus spp. and Enterococcus spp. to fosfomycin. Materials and Methods: A total of 194 isolates of Staphylococcus spp. and Enterococcus spp. were collected from urine samples of dogs diagnosed with bacterial cystitis. Bacterial identification and susceptibility to multiple antibiotics were tested using the Vitek 2 automated system. The susceptibility to fosfomycin was compared between agar dilution (reference method) and the gradient diffusion method. We assessed the agreement rates and errors between the two approaches by analyzing the MIC data. Results: Staphylococcus pseudintermedius (98.7%) and Enterococcus faecalis (80.0%) exhibited high fosfomycin susceptibility rates, whereas Enterococcus faecium exhibited a lower susceptibility rate (38.5%). The gradient diffusion method demonstrated unacceptably low essential agreement (EA) rates (>90%) but acceptable categorical agreement (CA) rates (≥ 90%) for S. pseudintermedius (83.54% EA and 97.47% CA) and coagulase-negative staphylococci (CoNS) such as Staphylococcus chromogenes, Staphylococcus hominis, and Staphylococcus simulans (85.00% EA and 95.00% CA). Enterococcus spp. had an acceptable EA of 93.75%, but an unacceptably low CA rate of 82.81%, with a minor error rate of 17.19%. No significant errors were observed for Staphylococcus and Enterococcus spp. Conclusion: The gradient diffusion method reliably determines MICs and interpretative breakpoints (S, I, R) for S. pseudintermedius. However, its applicability to CoNS and enterococci may be limited due to unacceptable errors. [ABSTRACT FROM AUTHOR]

Background: Diffusion magnetic resonance imaging (dMRI) provides a powerful tool to non‐invasively investigate neural structures in the living human brain. Nevertheless, its reconstruction performance on neural structures relies on the number of diffusion gradients in the q‐space. High‐angular (HA) dMRI requires a long scan time, limiting its use in clinical practice, whereas directly reducing the number of diffusion gradients would lead to the underestimation of neural structures. Purpose: We propose a deep compressive sensing‐based q‐space learning (DCS‐qL) approach to estimate HA dMRI from low‐angular dMRI. Methods: In DCS‐qL, we design the deep network architecture by unfolding the proximal gradient descent procedure that addresses the compressive sense problem. In addition, we exploit a lifting scheme to design a network structure with reversible transform properties. For implementation, we apply a self‐supervised regression to enhance the signal‐to‐noise ratio of diffusion data. Then, we utilize a semantic information‐guided patch‐based mapping strategy for feature extraction, which introduces multiple network branches to handle patches with different tissue labels. Results: Experimental results show that the proposed approach can yield a promising performance on the tasks of reconstructed HA dMRI images, microstructural indices of neurite orientation dispersion and density imaging, fiber orientation distribution, and fiber bundle estimation. Conclusions: The proposed method achieves more accurate neural structures than competing approaches. [ABSTRACT FROM AUTHOR]

Through a simple and effective method for preparing broadband reflective liquid crystal films, the advantages of the three‐layer system are expanded based on the two‐layer system. The cholesteric liquid crystals form a prepolymerized layer after semi‐curing. In the design of the top prepolymerization layer, there is less content of the chiral compound R5011, which results in the formation of cholesteric liquid crystal molecules with a larger pitch. Mainly by controlling the content of polymerizable monomers and UV‐absorbing dyes in cholesteric liquid crystals (CLCs), a polymer network with density gradient distribution suitable for substance diffusion is formed, and the oleophobic substrate on one side of the low‐density polymer network is more likely to be peeled off. In the design of the lowest prepolymerization layer, the content of R5011 is higher, which results in the formation of cholesteric liquid crystals with a larger pitch. One side substrate of two cholesteric liquid crystal cassettes is peeled off and merged into a new liquid crystal cassette whose left and right sides are stacked with septum pads (20 μm), and the nematic liquid crystals are poured into the middle layer to form a three‐layer integrated film. The polymer network of the polymer‐stabilized cholesteric liquid crystals (PSCLCs) itself in the bilayer was used as a diffusion channel. Chiral compounds and UV‐absorbing dyes were diffused from the cholesteric liquid crystal layer to the intermediate nematic liquid crystal layer by diffusion gradient method, resulting in liquid crystal films with arbitrary wavelength bands and ultrawide broadband reflection. [ABSTRACT FROM AUTHOR]

Premixed flames exhibit different asymptotic regimes of interaction between heat release and turbulence depending on their respective length scales. At high Karlovitz number, the dilatation caused by heat release does not have any relevant effect on turbulent kinetic energy with respect to non-reacting flow, while at low Karlovitz number, the mean shear is a sink of turbulent kinetic energy, and counter-gradient transport is observed. This latter phenomenon is not well captured by closure models commonly used in Large Eddy Simulations that are based on gradient diffusion. The massive amount of data available from Direct Numerical Simulation (DNS) opens the possibility to develop data-driven models able to represent physical mechanisms and non-linear features present in both these regimes. In this work, the databases are formed by DNSs of two planar hydrogen/air flames at different Karlovitz numbers corresponding to the two asymptotic regimes. In this context, the Generative Adversarial Network (GAN) gives the possibility to successfully recognize and reconstruct both gradient and counter-gradient phenomena if trained with databases where both regimes are included. Two GAN models were first trained each for a specific Karlovitz number and tested using the same dataset in order to verify the capability of the models to learn the features of a single asymptotic regime and assess its accuracy. In both cases, the GAN models were able to reconstruct the Reynolds stress subfilter scales accurately. Later, the GAN was trained with a mixture of both datasets to create a model containing physical knowledge of both combustion regimes. This model was able to reconstruct the subfilter scales for both cases capturing the interaction between heat release and turbulence closely to the DNS as shown from the turbulent kinetic budget and barycentric maps. [ABSTRACT FROM AUTHOR]

Liquid-liquid phase separation yields spherical droplets that eventually coarsen to one large, stable droplet governed by the principle of minimal free energy. In chemically fueled phase separation, the formation of phase-separating molecules is coupled to a fuel-driven, non-equilibrium reaction cycle. It thus yields dissipative structures sustained by a continuous fuel conversion. Such dissipative structures are ubiquitous in biology but are poorly understood as they are governed by non-equilibrium thermodynamics. Here, we bridge the gap between passive, close-to-equilibrium, and active, dissipative structures with chemically fueled phase separation. We observe that spherical, active droplets can undergo a morphological transition into a liquid, spherical shell. We demonstrate that the mechanism is related to gradients of short-lived droplet material. We characterize how far out of equilibrium the spherical shell state is and the chemical power necessary to sustain it. Our work suggests alternative avenues for assembling complex stable morphologies, which might already be exploited to form membraneless organelles by cells. Dissipative structures are governed by non-equilibrium thermodynamics. Here, the authors describe a size-dependent transition from active droplets to active spherical shells—a dissipative structure that arises from reaction diffusion gradients. [ABSTRACT FROM AUTHOR]

Sequentially managing the coverage and dimerization of *CO on the Cu catalysts is desirable for industrial-current-density CO2 reduction (CO2R) to C2+, which required the multiscale design of the surface atom/architecture. However, the oriented design is colossally difficult and even no longer valid due to unpredictable reconstruction. Here, we leverage the synchronous leaching of ligand molecules to manipulate the seeding-growth process during CO2R reconstruction and construct Cu arrays with favorable (100) facets. The gradient diffusion in the reconstructed array guarantees a higher *CO coverage, which can continuously supply the reactant to match its high-rate consumption for high partial current density for C2+. Sequentially, the lower energy barriers of *CO dimerization on the (100) facets contribute to the high selectivity of C2+. Profiting from this sequential *CO management, the reconstructed Cu array delivers an industrial-relevant FEC2+ of 86.1% and an FEC2H4 of 60.8% at 700 mA cm-2. Profoundly, the atomic-molecular scale delineation for the evolution of catalysts and reaction intermediates during CO2R can undoubtedly facilitate various electrocatalytic reactions. [ABSTRACT FROM AUTHOR]

Fractional calculus and fractional-order calculus are arranged in lineage as regards the mathematical models with complexity-theoretical tenets capable of capturing the subtle molecular dynamics by the integration of power-law convolution kernels into time- and space-related derivatives emerging in equations concerning the Magnetic Resonance Imaging (MRI) phenomena to which the fractional models of diffusion and relaxation are applied. Endowed with an intricate level of complexity and a unique physical and structural scaffolding at molecular and cellular levels with numerous synapses forming elaborate neural networks which entail in-depth probing and computing of patterns and signatures in individual cells and neurons, human brain as a heterogeneous medium is constituted of tissues with cells of different sizes and shapes, distributed across an extra-cellular space. Characterization of the unique brain cells is sought after to unravel the connections between different cells and tissues for accurate, reliable, robust and optimal models and computing. Accordingly, Diffusion Magnetic Resonance Imaging (DMRI), as a noninvasive and experimental imaging technique with clinical and research applications, provides a measure related to the diffusion characteristics of water in biological tissues, particularly in the brain tissues. Compatible with these aspects and beyond the diffusion coefficients' measurement, DMRI technique aims to exceed the spatial resolution of the MRI images and draw inferences from the microstructural properties of the related medium. Thus, novel tools become essential for the description of the biological (organelles, membranes, macromolecules and so on) and neurological (axons, dendrites, neurons and so forth) tissues' complexity. Mathematical model-based computational analyses with multifaceted methods to extract information from the DMRI with SpinDoctor into neuronal dynamics can provide quantitative parametric instruments in order to reflect the tissue properties focusing on the precise link between the tissue microstructure and signals acquired by employing advanced medical imaging technologies. Coalesced with accurate neuron geometry models as well as numerical DMRI simulations, a novel extended and multifaceted predictive mathematical model based on SpinDoctor and Bloch–Torrey partial differential equation (BTPDE) with the Caputo fractional-order derivative (FOD) with three-parameter (α , β , δ) Mittag-Leffler function (MLF) has been proposed and developed in our study by extending for the application on Brain Neuron Spin Unit dataset with the relevant multi-stage application-related steps. The feedforward neural networks (FFNNs) with BFGS Quasi-Newton equation, as one of the artificial neural network (ANN) algorithms, are applied on BTPDE with Caputo fractional-order derivative for the neurons and their algorithmic complexity is computed by building a BTPDE with Caputo FOD Neuron model based on different fractional orders. The fractional-order degree of the proposed and developed model is applied in relation to their corresponding complexity degrees. Consequently, experimentation and observations from the simulation-driven FFNN (with BFGS Quasi-Newton equation) learning scheme applied to the Bloch–Torrey PDE–Caputo FOD with MLF Neuron model (named as FFNN–BTPDE–CFODMLF Neuron model) proposed in this study, are made. Thus, by investigating whether the mathematical models based on the accurate neuron geometry models obtained can be optimized by comparing the errors in order to define the order parameter and identify to what optimal extent the errors are in relation to the prediction results with a particular focus on the neuron model, we have been able to estimate and predict brain microstructure through DMRI, accentuating mathematical and medical contributions based on the exploitation and corroboration of powerful modeling as well as computational capabilities. [ABSTRACT FROM AUTHOR]

Since diffusion-weighted imaging (DWI) images are high-dimensional medical images with rich texture features, existing traditional zero-watermarking algorithms cannot effectively protect the copyright of DWI images while satisfying the conditions of equilibrium and distinguishability. In this paper, a robust zero-watermarking algorithm for DWI images based on multiscale feature fusion is proposed to achieve effective copyright protection of DWI images. Firstly, a Siamese network for multiscale feature extraction based on the imaging characteristics of DWI images is proposed to extract robust features of two-dimensional slice sequences in each diffusion gradient direction by using different transforms. Next, to address the low distinguishability of extracted features due to the similar anatomical structure of different people under the same medical imaging mode, a variety of features based on texture and spatial correlations are integrated as a prior knowledge features into the network to enhance the distinguishability of zero-watermarking. Then, the dimensionality of the extracted features is reduced by using a clustering algorithm, and the key slice images are selected in each category of each diffusion gradient direction by using the clustering results. The eigenvalues of the eigenmatrix of the key slices are extracted by singular value decomposition to generate a binary feature map according to the gray average of the eigenvalue matrix. Finally, the binary feature map and the watermarking signals are modulated by logic chaos, and the zero-watermarking information is generated by performing the XOR operation. The experimental results show that the proposed algorithm is robust against various intentional or unintentional attacks on medical image processing, such as noise, filtering, JPEG compression and geometric attacks. The extraction accuracy rate of watermarking is above 97%, and it is more robust than traditional robust zero-watermarking methods. [ABSTRACT FROM AUTHOR]

Although the existing cardiac diffusion tensor imaging (DTI) denoising methods have achieved promising results, most of them are dependent on the number of diffusion gradient directions, noise distributions, and noise levels. To address these issues, we propose a novel self-supervised cardiac DTI denoising network, Node2Node, which firstly expresses the diffusion-weighted (DW) image volumes along different directions as a graph, then the graph framelet transform (GFT) is implemented to map the DW signals into the GFT coefficients at different spectral bands, allowing us to accurately match the DW image pairs. After that, using the matched image pairs as input and target, a ResNet-like network is used to denoise in a self-supervised manner. In addition, a novel edge-aware loss based on pooling operation is proposed to retain the edge. Through comparison with several state-of-the-art methods on synthetic, ex vivo porcine, and in vivo human cardiac DTI datasets, we showed that the root mean square error (RMSE) of DW images and the average angular error (AAE) of fiber orientations obtained using Node2Node are the smallest, improved by 47.5% and 23.7%, respectively, on the synthetic dataset, demonstrating that Node2Node is not sensitive to the properties of the dataset. [ABSTRACT FROM AUTHOR]

Purpose: Preliminary study to determine whether double pulsed field gradient (PFG) diffusion MRI is sensitive to key features of muscle microstructure related to function. Methods: The restricted diffusion profile of molecules in models of muscle microstructure derived from histology were systematically simulated using a numerical simulation approach. Diffusion tensor subspace imaging analysis of the diffusion signal was performed, and spherical anisotropy (SA) was calculated for each model. Linear regression was used to determine the predictive capacity of SA on the fiber area, fiber diameter, and surface area to volume ratio of the models. Additionally, a rat model of muscle hypertrophy was scanned using a single PFG and a double PFG pulse sequence, and the restricted diffusion measurements were compared with histological measurements of microstructure. Results: Excellent agreement between SA and muscle fiber area (r2 = 0.71; p < 0.0001), fiber diameter (r2 = 0.83; p < 0.0001), and surface area to volume ratio (r2 = 0.97; p < 0.0001) in simulated models was found. In a scanned rat leg, the distribution of these microstructural features measured from histology was broad and demonstrated that there is a wide variance in the microstructural features observed, similar to the SA distributions. However, the distribution of fractional anisotropy measurements in the same tissue was narrow. Conclusions: This study demonstrates that SA—a scalar value from diffusion tensor subspace imaging analysis—is highly sensitive to muscle microstructural features predictive of function. Furthermore, these techniques and analysis tools can be translated to real experiments in skeletal muscle. The increased dynamic range of SA compared with fractional anisotropy in the same tissue suggests increased sensitivity to detecting changes in tissue microstructure. [ABSTRACT FROM AUTHOR]

This article compares two methods, the ETEST® superposition method and the MTS™ Aztreonam-avibactam strip, with the reference method for determining the susceptibility of aztreonam/avibactam. The study used a collection of 145 clinical isolates that produce carbapenemase-producing Gram-negative bacteria (GNB) and are resistant to aztreonam. The results showed that the MTS™ Aztreonam-avibactam strip had a higher concordance with the reference method compared to the ETEST® superposition method. The study concludes that the MTS™ Aztreonam-avibactam strip is an easy-to-use option for routine testing. [Extracted from the article]

This paper focuses on tracing the connectivity of white matter fascicles in the brain. In particular, a generalized order algorithm based on mixture of non-central Wishart distribution model is proposed for this purpose. The proposed algorithm utilizes the generalization of integer order based approach with the mixture of non-central Wishart distribution model. Pseudo super anomalous behavior of water diffusion inside human brain is the prime motivation of the the present study. We have shown results on multiple synthetic simulations with fibers orientations in two and three directions in each voxel as well as experiments on real data. Synthetic simulations were performed with varying noise levels and diffusion weighting gradient i.e. |$b-$| values. The proposed model performed outstanding especially for distinguishing closely oriented fibers. [ABSTRACT FROM AUTHOR]

The capillary fringe (CF) is a well-known zone of tension saturation immediately above the water table and has significant influence on solute transport in soil profile, yet the CF has not been included in available models for contaminant transport in composite liners. This study presents an exact analytical solution to thermal gradient enhanced diffusion of organic contaminants through unsaturated composite liner considering the existence of CF. The exact solution is obtained by the separation of variables method and validated by two existing analytical solutions and a numerical model. The influence of CF on the diffusion of two organic contaminants is analyzed under different desaturation coefficients, Soret coefficients, and the temperature difference between the upper and the bottom surfaces of the composite liner. A corresponding simplified solution is also proposed by using a new Robin-type boundary and evaluated for engineering practice. The mass flux by thermal diffusion is considered when developing the new Robin-type boundary. The results show that the CF has a remarkable influence on contaminant diffusion in unsaturated composite liners and the influence is more distinct for unsaturated composite liners with higher desaturation coefficient. The enhancement of thermal diffusion process by the increase of Soret coefficient and the temperature difference between the upper and the bottom surfaces of the composite liner is more significant if the CF is included in the diffusion model. The simplified solution shows excellent performance when the CF is not considered and when the desaturation coefficient is low (e.g., 0.1 m−1) regardless of the variations of CF and Soret coefficient. The results are useful for analyzing organic contaminants diffusion through unsaturated composite liners considering the existence of CF and thermal effects in both theory and engineering practice. [ABSTRACT FROM AUTHOR]

Here, we examine the behavior of micropolar fluids as they travel through a curved stretching surface. We integrate thermo‐diffusion and diffusion‐thermo effects into the temperature and concentration equations to study the impact of cross‐diffusion gradients on velocities, temperatures, and concentrations. The equations governing the flow are nonlinear, thus by applying practical similarity transformations, we obtain a system of nonlinear ordinary differential equations that can be solved. Using the Runge–Kutta numerical procedure, we are able to determine an answer to the modified system. The profiles of velocity, concentration, and temperature are shown, along with the influence of non‐dimensional parameters on those variables. The skin friction coefficient, as well as the Nusselt and Sherwood numbers, is computed numerically, and their fluctuations as a function of various parameters are investigated. The implications of these findings for engineering and industry are greater. [ABSTRACT FROM AUTHOR]

Relaxation rates R1ρ in the rotating frame measured by spin‐lock methods at very low locking amplitudes (≤ 100 Hz) are sensitive to the effects of water diffusion in intrinsic gradients and may provide information on tissue microvasculature, but accurate estimates are challenging in the presence of B0 and B1 inhomogeneities. Although composite pulse preparations have been developed to compensate for nonuniform fields, the transverse magnetization comprises different components and the spin‐lock signals measured do not decay exponentially as a function of locking interval at low locking amplitudes. For example, during a typical preparation sequence, some of the magnetization in the transverse plane is nutated to the Z‐axis and later tipped back, and so does not experience R1ρ relaxation. As a result, if the spin‐lock signals are fit to a monoexponential decay with locking interval, there are residual errors in quantitative estimates of relaxation rates R1ρ and their dispersion with weak locking fields. We developed an approximate theoretical analysis to model the behaviors of the different components of the magnetization, which provides a means to correct these errors. The performance of this correction approach was evaluated both through numerical simulations and on human brain images at 3 T, and compared with a previous correction method using matrix multiplication. Our correction approach has better performance than the previous method at low locking amplitudes. Through careful shimming, the correction approach can be applied in studies using low spin‐lock amplitudes to assess the contribution of diffusion to R1ρ dispersion and to derive estimates of microvascular sizes and spacings. The results of imaging eight healthy subjects suggest that R1ρ dispersion in human brain at low locking fields arises from diffusion among inhomogeneities that generate intrinsic gradients on a scale of capillaries (~7.4 ± 0.5 μm). [ABSTRACT FROM AUTHOR]

Purpose: To develop a time‐efficient pulse sequence that acquires multiple diffusion‐weighted images with distinct diffusion times in a single shot by using multiple stimulated echoes (mSTE) with variable flip angles (VFA). Methods: The proposed diffusion‐weighted mSTE with VFA (DW‐mSTE‐VFA) sequence begins with two 90° RF pulses that straddle a diffusion gradient lobe (GD) to excite and restore one half of the magnetization into the longitudinal axis. The restored longitudinal magnetization was successively re‐excited by a series of RF pulses with VFA, each followed by another GD, to generate a set of stimulated echoes. Each of the multiple stimulated echoes was acquired with an EPI echo train. As such, the train of multiple stimulated echoes produced a set of diffusion‐weighted images with varying diffusion times in a single shot. This technique was experimentally demonstrated on a diffusion phantom, a fruit, and healthy human brain and prostate at 3 T. Results: In the phantom experiment, the mean ADC measured at different diffusion times using DW‐mSTE‐VFA were highly consistent (r = 0.999) with those from a commercial spin‐echo diffusion‐weighted EPI sequence. In the fruit and brain experiments, DW‐mSTE‐VFA exhibited similar diffusion‐time dependence to a standard diffusion‐weighted stimulated echo sequence. The ADC showed significant time dependence in the human brain (p = 0.003 in both white matter and gray matter) and prostate tissues (p = 0.003 in both peripheral zone and central gland). Conclusion: DW‐mSTE‐VFA offers a time‐efficient tool for investigating the diffusion‐time dependency in diffusion MRI studies. [ABSTRACT FROM AUTHOR]

Objective: To study the origin of compartment size overestimation in double diffusion encoding MRI (DDE) in vivo experiments in the human corticospinal tract. Here, the extracellular space is hypothesized to be the origin of the DDE signal. By exploiting the DDE sensitivity to pore shape, it could be possible to identify the origin of the measured signal. The signal difference between parallel and perpendicular diffusion gradient orientation can indicate if a compartment is regular or eccentric in shape. As extracellular space can be considered an eccentric compartment, a positive difference would mean a high contribution to the compartment size estimates. Materials and methods: Computer simulations using MISST and in vivo experiments in eight healthy volunteers were performed. DDE experiments using a double spin-echo preparation with eight perpendicular directions were measured in vivo. The difference between parallel and perpendicular gradient orientations was analyzed using a Wilcoxon signed-rank test and a Mann–Whitney U test. Results: Simulations and MR experiments showed a statistically significant difference between parallel and perpendicular diffusion gradient orientation signals ( α = 0.05 ). Conclusion: The results suggest that the DDE-based size estimate may be considerably influenced by the extra-axonal compartment. However, the experimental results are also consistent with purely intra-axonal contributions in combination with a large fiber orientation dispersion. [ABSTRACT FROM AUTHOR]

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Background: Liver diseases represent a significant global health concern, necessitating accurate detection and characterization of focal liver lesions (FLLs). Precise differentiation between benign and malignant lesions, as well as distinguishing primary liver lesions from metastases, is pivotal for effective clinical management. This study aims to compare the efficacy of respiratory-triggered diffusion-weighted single-shot echo planar imaging (RT DW-SS-EPI) and T2 weighted turbo spin echo imaging (T2W TSE) in detecting and characterizing FLLs. Additionally, the study aims to determine the apparent diffusion coefficients (ADCs) of FLLs and normal liver parenchyma. Methods: A total of 30 patients with suspected focal liver lesions and 10 healthy volunteers without FLLs were enrolled. Patients referred for MRI with clinical suspicion of FLLs were included. The study employed respiratory-triggered fat-suppressed singleshot echo-planar DW imaging in the transverse plane with tridirectional diffusion gradients and three b values (0, 500, and 1000 sec/mm²). ADC maps were generated, and routine MR sequences were obtained using a 1.5 Tesla MRI scanner. ADC values were calculated using operator-defined regions of interest (ROIs), and differences in ADC values were analyzed. Results: The study encompassed 85 lesions in 30 patients, including 23 hepatocellular carcinomas (HCCs), 4 cholangiocellular carcinomas, 36 metastatic lesions, and 22 benign lesions. Males comprised 63.3% of participants. DWI demonstrated significantly higher FLL detection rates than T2WI (p < 0.001), particularly for malignant lesions (98.4% with DWI vs. 76.5% with T2WI). No significant difference was observed in detecting HCCs alone. DWI exhibited superior detection capabilities for both liver lobes compared to T2WI. Mean ADC values for various lesion types showed significant differences, with malignant lesions displaying lower ADC values than benign lesions (p < 0.001). Conclusion: Respiratory-triggered diffusion-weighted MRI (RT DWI) emerges as a valuable and contrast-free diagnostic tool for detecting and characterizing focal liver lesions. DWI outperformed T2 weighted imaging in detecting malignant lesions and showed potential for accurate differentiation between benign and malignant lesions based on ADC values. The study highlights DWI's clinical utility for liver lesion evaluation in routine practice. [ABSTRACT FROM AUTHOR]