Changes In Diffusion Coefficient Research Articles

Interval changes of histogram-derived diffusion indices predict treatment response to induction chemotherapy in head and neck cancer: a feasibility study.

This retrospective study investigated whether the interval change of apparent diffusion coefficient (∆ADC) [baseline and after the first cycle of induction chemotherapy (ICT)] can be used as a valid predictive imaging biomarker of the treatment response to ICT in head and neck cancer (HNC). A total of 19 consecutive patients with HNC who underwent diffusion-weighted magnetic resonance imaging (DWI) at baseline and after the first cycle of ICT were included. Whole-tumor ADC histogram parameters (mean, median, kurtosis, skewness, entropy, minimal, maximum, 25th percentile, and 75th percentile) were obtained. The correlations of ∆ADC histogram parameters, volume, T-stage, N-stage, and age with the treatment response were examined using the Mann-Whitney U test. The predictive value of histogram parameters was examined using receiver operating characteristic (ROC) curves. Responders showed significantly higher values of ∆ADC25 (0.19±0.23) and ∆ADCmin (1.78±2.98) than non-responders (-0.09±0.15 and -0.73±0.36; P=0.035 and 0.009, respectively). When ∆ADC25 and ∆ADCmin were used for predicting the treatment response, the area under the ROC curve was 0.850/0.933 with a sensitivity of 73.3%/80.0% and specificity of 100%/100% (P=0.036 and 0.009, respectively). ∆ADC25 and ∆ADCmin derived from whole-tumor histogram analysis are valuable imaging biomarkers for the early prediction of the ICT response in HNC.

Quantitative analysis of age-related changes in cervical lymph nodes using diffusion-weighted imaging

ObjectivesThis study aimed to investigate age-related changes in apparent diffusion coefficient (ADC) values of cervical lymph nodes using diffusion-weighted imaging (DWI). MaterialsWe conducted a retrospective cohort study of patients who underwent pantomography and magnetic resonance imaging (MRI) between November 2017 and July 2018. The participants comprised 101 patients with 389 nodes (males: 22, females: 79, mean age: 44.33 [range: 14–77] years). The correlation between the age group of the criterion variable and ADC value of the explanatory variable was analyzed using Spearman's correlation coefficient. p < 0.05 was considered statistically significant. ResultsThere was a significant negative correlation between age and the ADC values for each sex (p < 0.001). The mean ADC value of the submandibular nodes for all age groups was 0.88 ± 0.15 × 10−3 mm2/s in men and 0.83 ± 0.12 × 10−3 mm2/s in women (p = 0.211). The mean ADC value of the superior internal jugular nodes for all age groups was 0.90 ± 0.14 × 10−3 mm2/s in men and 0.91 ± 0.16 × 10−3 mm2/s in women (p = 0.857). ConclusionsThis study demonstrated that normal ADC values of cervical lymph nodes exhibited significant negative correlation with increasing age. These findings could be useful for the diagnosis of cervical lymph node diseases, including malignant tumors.

CTNI-67. DUAL INHIBITION OF POST-RADIOGENIC ANGIO-VASCULOGENESIS BY OLAPTESED PEGOL (NOX-A12) AND BEVACIZUMAB IN GLIOBLASTOMA – INTERIM DATA FROM THE FIRST EXPANSION ARM OF THE GERMAN PHASE 1/2 GLORIA TRIAL

Abstract BACKGROUND We recently reported favorable safety, promising clinical efficacy and immunohistochemical indicators of response after radiotherapy (RT) plus escalating doses of the CXCL12-neutralizing RNA-Spiegelmer olaptesed pegol (NOX-A12) for glioblastoma in the German multicenter phase 1/2 GLORIA trial (NCT04121455). Here, we report outcomes after RT plus dual inhibition of vasculogenesis (NOX-A12) and angiogenesis (bevacizumab). METHODS After establishing safety in the monotherapy arm, we enrolled six patients with incompletely resected GBM, ECOG ≤ 2, age ≥ 18 and without MGMT promoter hypermethylation into a pre-planned expansion arm. Patients received standard RT (60 Gy in 30 fractions), continuous i.v. infusions of NOX-A12 (600 mg/week) and i.v. infusions of bevacizumab (10 mg/kg q2w). The primary endpoint was safety. Secondary endpoints included radiographic response, perfusion/diffusion imaging and neurologic performance. RESULTS Dual treatment was well-tolerated and safe. Of all G ≥ 2 AEs (n = 37), two G2 events (5.4%) were deemed related to NOX-A12. There were no dose-limiting toxicities and no treatment-related deaths. Longitudinal NANO assessment revealed stable neurologic functioning in all patients. Five out of six patients achieved partial responses (PRs) as per mRANO in week 9. All PRs remained durable at a median follow up of 5.6 months (range 3.6 to 9.3 months). No progression occurred. The mean best response was -65.9% (-13.3% to -99.9%) for target lesion sums and -92.1% (-76.2% to -100%) for non-target lesion (NTL) sums. In all three patients with NTL at least one lesion disappeared. The mean best change from baseline of the highly perfused-tumor fraction was -84.5% (-51.9% to -100%) and the mean best change of the apparent diffusion coefficient was 20.1% (-24.5% to 59.1%). CONCLUSION Interim data of the ongoing trial confirm the previously established safety profile of NOX-A12 and suggest improved efficacy of dual inhibition of post-radiogenic angio- and vasculogenesis by the addition of bevacizumab.

Experimental Research to Determine the Effect of Ultrasound in Drying Bo Chinh Ginseng by Ultrasound-Assisted Heat Pump Drying Method

This study focused on the experimental drying of Bo Chinh ginseng by the ultrasound-assisted heat pump drying method, in which the effects of drying air temperature (T), ultrasonic power (P), intermittency ratio of ultrasound generator (A) on the moisture effective diffusion coefficient (Deff), saponin content (Sp) and color change (dE) during the drying process were determined. The results showed that the drying time was reduced from 12.5 h at 35 °C to 8.9 h at 40 °C and greatly reduced to 5.8 h at 55 °C. The moisture diffusion coefficient Deff and color change index increased with the increase in drying temperature. Meanwhile, from 35 °C to 45 °C, the saponin content after drying tended to increase gradually, but when the temperature continued to rise from 45 °C to 55 °C, the saponin content decreased. The effect of ultrasonic power in the drying process was in particular as follows. The drying time of 8.8 h at 40 W ultrasonic power reduced to 7.8 h at 80 W ultrasonic power, and reduced to 7 h at 160 W ultrasonic power. The remaining saponin content after drying tended to increase gradually at the power level of 40–120 W (from 89.2% to 95.2%) and decrease when the power increased from 120 to 160 W (from 95.2% to 90.5%). The moisture diffusion coefficient Deff also increased with the increase in ultrasonic power. Meanwhile, the color change of dried products decreased as the ultrasonic power increased in the range of 40–120 W but increased with the ultrasonic power range from 120 to 160 W. Additionally, the experimental method and Box–Behnken design were used for optimizing the drying process with the optimal drying conditions such as drying air temperature of 45.2 °C, ultrasonic power of 127.7 W and intermittency ratio of ultrasound generator of 0.18.

Capturing the start point of the virus-cell interaction with high-speed 3D single-virus tracking.

The early stages of the virus-cell interaction have long evaded observation by existing microscopy methods due to the rapid diffusion of virions in the extracellular space and the large three-dimensional cellular structures involved. Here we present an active-feedback single-particle tracking method with simultaneous volumetric imaging of the live cell environment called 3D-TrIm to address this knowledge gap. 3D-TrIm captures the extracellular phase of the infectious cycle in what we believe is unprecedented detail. We report what are, to our knowledge, previously unobserved phenomena in the early stages of the virus-cell interaction, including skimming contact events at the millisecond timescale, orders of magnitude change in diffusion coefficient upon binding and cylindrical and linear diffusion modes along cellular protrusions. Finally, we demonstrate how this method can move single-particle tracking from simple monolayer culture toward more tissue-like conditions by tracking single virions in tightly packed epithelial cells. This multiresolution method presents opportunities for capturing fast, three-dimensional processes in biological systems.

Quantitative analysis of tongue changes with aging using diffusion‐weighted magnetic resonance imaging

AbstractObjectiveThis study aimed to quantitatively assess the changes in the apparent diffusion coefficient (ADC) value of the tongue with aging using diffusion‐weighted imaging (DWI).MethodsIn this retrospective study, we analyzed the ADC map of 480 patients (230 men, 250 women; mean age, 53.66 years; age range, 20–89 years) with the tongue not affected by disease, between January 2018, and February 2020. The Mann–Whitney U test was performed with the ADC value as the explanatory variable and the sex as the criterion variable. Moreover, we calculated the Spearman's correlation coefficient with age as the criterion variable and ADC value as the explanatory variable.ResultsA significantly positive correlation was found between age and ADC values of the tongue in the men and women groups (P &lt; 0.001). However, no significant differences were observed between the sex and the ADC values of the tongue (P = 0.19).ConclusionsThese findings suggest that age should be taken into consideration when making a differential diagnosis of the tongue using ADC values.

Branched Glucan from Leuconostoc Mesenteroides as the channel for ionic migration in the fabrication of protonic (H+) battery

This research paper reports the characteristics of dextran-glycerol-ammonium hexafluorophosphate (NH4PF6) electrolyte system and application in proton batteries. The solid polymer electrolyte films are obtained by solution cast method. Interaction between dextran, glycerol and NH4PF6 salt is examined using Fourier transform infrared spectroscopy (FTIR) analysis. Electrolyte with 18 wt.% NH4PF6 exhibits the highest room temperature conductivity of (1.43 ± 0.16) × 10−4 S cm−1. It is inferred that the conductivity is mainly controlled by the changes in ionic mobility and diffusion coefficient. Field emission scanning electron microscopy (FESEM) analysis shows the difference in the morphology with respect to NH4PF6 content and verifies the conductivity result. Differential scanning calorimetry (DSC) analysis confirms that the presence of plasticizer and 18 wt.% salt has decreased the glass transition temperature (Tg). The temperature dependence of conductivity for the highest conducting electrolyte shows a typical Vogel-Tamman-Fulcher (VTF) behavior. The proton batteries have been discharged at different constant currents.

Molecular Simulation of the Effects of Cyclic Organic Compounds on the Stability of Lccbm Hydrates.

CH4 can be separated from low-concentration coal bed methane (LCCBM) by using the hydrate-based gas separation (HBGS) method. To study the contribution of different cyclic organic compounds to the separation of CH4 in LCCBM, an LCCBM hydrate model was constructed. Based on the Monte Carlo and molecular dynamics theory, we simulated the effect of three cyclic organic compounds—cyclopentane (CP), cyclopentanone (CP-one), and cyclopentanol (CP-ol)—on the stability of the LCCBM hydrate at P = 2 MPa, various temperatures, and discussed the structural stability of the hydrate in depth in terms of final snapshots, radial distribution function, mean square displacement, diffusion coefficient, and potential energy change. The results showed that for the CH4-N2 LCCMM gas mixture, CP showed the best facilitation effect compared to the other two cyclic compounds by maintaining the stability of the LCCBM hydrate well at T = 293 K. The promotion effect of CP-one is between CP and CP-ol, and when the temperature increases to T = 293 K, the oxygen atoms in the water molecule can maintain the essential stability of the hydrate structure, although the orderliness decreases significantly. Moreover, the structure of the hydrate model containing CP-ol is destroyed at T = 293 K, and the eventual escape of CH4 and N2 molecules in solution occurs as bubbles. The research results are important for further exploration of the mechanism of action of cyclic promoter molecules with LCCBM hydrate molecules and promoter preferences.

Assessment of Durability Indicators for Service Life Prediction of Portland Limestone Cementitious Systems Produced with Permeability-Reducing Admixtures

Supplementary cementing materials (SCMs) and the challenges associated with admixture compatibility and durability performance are continuous challenges for the construction industry. Utilizing SCMs has apparent benefits in reducing the carbon footprint and improving the durability performance of concrete structures. This work investigates the performance of mortars composed of Portland limestone cement, calcium carbonate, butyl stearate, and oleic acid. The effort focuses on transport properties using electrical resistivity, chloride migration, porosity, and water permeability measurements. Then, various methods based on the last parameters are compared to assess the changes in the effective chloride diffusion coefficient and the intrinsic liquid water permeability. Measurements for drying shrinkage, thermal expansion, and compressive strength are conducted to verify durability and mechanical performance. The effect of the admixture addition on the service life of a structure fully submerged in marine exposure conditions is then evaluated using Fick’s second law of diffusion and the approach described by FIB model code 34. The results indicate that incorporating calcium carbonate, butyl stearate, and oleic acid in mortar mixtures provides enhanced durability compared to plain Portland limestone cement mortars.

MRI Imaging Omics and Risk Factors Analysis of PWMD in Premature Infants Based on Fuzzy Clustering Algorithm.

The magnetic resonance imaging (MRI) characteristics of periventricular white matter damage (PWMD) in premature infants using the fuzzy c-means clustering algorithm (FCM) is explored, and the influencing factors are further clarified. A total of 100 premature infants admitted to the neonatal department of our hospital from February 2020 to February 2022 are selected for in-depth investigation. According to the occurrence of PWMD, they are divided into the PWMD group and the simple premature delivery group, with 50 cases in each group. All preterm infants are examined by MRI and the changes in image characteristics and apparent diffusion coefficient (ADC) values are analyzed. Clinical information of the subjects is collected and the influencing factors of PWMD in preterm infants are analyzed by multivariate regression analysis. In the first magnetic resonance imaging (MRI) examination, the cases of punctured, clustered, and linear lesions are 28 cases, 12 cases, and 10 cases, respectively. The experimental results showed that PWMD of preterm infants presented punctate, clustered, and high linear T1 signal MRI manifestations, which caused a downward trend of ADC value, and caused respiratory distress, low birth weight, premature rupture of membranes, respiratory tract infection, and other risk symptoms.

Diffusion-Weighted MRI for Predicting Pathologic Complete Response in Neoadjuvant Immunotherapy.

Simple SummaryImmunotherapy targets patients’ immune systems to fight cancer. The aim of this retrospective study is to assess tumor response to pre-operative immunotherapy and predict pathologic complete response using MRI at an early treatment time- point. Based on our analysis with a cohort from the multi-center I-SPY 2 clinical trial, we found diffusion-weighted MRI is superior to dynamic contrast-enhanced MRI, where the latter is a standard and most-commonly used MRI modality, in assessing immunotherapy, while no significant difference was observed in the control cohort where only standard chemotherapy was provided.This study tested the hypothesis that a change in the apparent diffusion coefficient (ADC) measured in diffusion-weighted MRI (DWI) is an independent imaging marker, and ADC performs better than functional tumor volume (FTV) for assessing treatment response in patients with locally advanced breast cancer receiving neoadjuvant immunotherapy. A total of 249 patients were randomized to standard neoadjuvant chemotherapy with pembrolizumab (pembro) or without pembrolizumab (control). DCE-MRI and DWI, performed prior to and 3 weeks after the start of treatment, were analyzed. Percent changes of tumor ADC metrics (mean, 5th to 95th percentiles of ADC histogram) and FTV were evaluated for the prediction of pathologic complete response (pCR) using a logistic regression model. The area under the ROC curve (AUC) estimated for the percent change in mean ADC was higher in the pembro cohort (0.73, 95% confidence interval [CI]: 0.52 to 0.93) than in the control cohort (0.63, 95% CI: 0.43 to 0.83). In the control cohort, the percent change of the 95th percentile ADC achieved the highest AUC, 0.69 (95% CI: 0.52 to 0.85). In the pembro cohort, the percent change of the 25th percentile ADC achieved the highest AUC, 0.75 (95% CI: 0.55 to 0.95). AUCs estimated for percent change of FTV were 0.61 (95% CI: 0.39 to 0.83) and 0.66 (95% CI: 0.47 to 0.85) for the pembro and control cohorts, respectively. Tumor ADC may perform better than FTV to predict pCR at an early treatment time-point during neoadjuvant immunotherapy.

Effect of atmospheric temperature on underground radon: A laboratory experiment

The effect of atmospheric temperature on underground radon flow was investigated in a customized climate-controlled laboratory (CCL) system, which enabled us to isolate the impact of ambient atmospheric temperature variations on underground radon transport. The soil thermal gradients that developed, following atmospheric warming, acted as the driving force for the diffusive radon flow, resulting in a decrease in the radon concentration along the experimental column setup at a rate of ∼70 Bq∙m−3 per oC∙m−1 (∼0.4% of the radon concentration). When the ambient temperature decreased, compared to the soil temperature, an air-soil temperature difference developed along the column, which acted as a driving force for radon to flow along the column and promptly increased the radon concentration at a rate of ∼140 Bq∙m−3 per oC (∼0.8% of the radon concentration). The overall radon concentration changes under the experimental conditions were up to 30%. The changes in the molecular diffusion coefficient in the experimental temperature range were ∼7%, with thermal diffusion as a possible additional mechanism contributing to radon transport due to temperature. The cyclic changes in ambient temperature in the forced conditions experiments were found to be directly correlated with underground radon oscillations. The same frequency for ambient temperature and radon concentration, along the experimental column in low frequency warming-cooling cycles (i.e., 4–8 days), was found. This good correlation was lost at higher frequencies (two days or more), due to the asymmetrical response of radon to atmospheric warming and cooling. The results of this study explain some of the field observations in underground radon monitoring.

Changes in Apparent Diffusion Coefficient (ADC) in Serial Weekly MRI during Radiotherapy in Patients with Head and Neck Cancer: Results from the PREDICT-HN Study.

Background: The PREDICT-HN study aimed to systematically assess the kinetics of imaging MR biomarkers during head and neck radiotherapy. Methods: Patients with intact squamous cell carcinoma of the head and neck were enrolled. Pre-, during, and post-treatment MRI were obtained. Serial GTV and ADC measurements were recorded. The correlation between each feature and the GTV was calculated using Spearman’s correlation coefficient. The linear mixed model was used to evaluate the change in GTV over time. Results: A total of 41 patients completed the study. The majority (76%) had oropharyngeal cancer. A total of 36 patients had intact primary tumours that can be assessed on MRI, and 31 patients had nodal disease with 46 nodes assessed. Median primary GTV (GTVp) size was 14.1cc. The rate of GTVp shrinkage was highest between pre-treatment and week 4. Patients with T3-T4 tumours had a 3.8-fold decrease in GTVp compared to T1-T2 tumours. The ADC values correlated with residual GTVp. The median nodal volume (GTVn) was 12.4cc. No clinical features were found to correlate with GTVn reduction. The overall change in ADC for GTVn from pre-treatment was significant for 35th–95th percentiles in weeks 1–4 (p < 0.001). Conclusion: A discrepancy in the trajectory of ADC between primary and nodal sites suggested that they exhibit different treatment responses and should be analysed separately in future studies.

Diffusion of cesium in oxidized and unoxidized IG-110 nuclear graphite

Time-release diffusion measurements of cesium have been conducted over the temperature range 1073 K – 1973 K on oxidized and unoxidized IG-110 graphite. Four cesium concentrations were tested to investigate the concentration dependence of the diffusion coefficient. Two levels of oxidation were tested and compared to unoxidized concentration-matched sets to explore the effects of graphite oxidation. The results demonstrate that cesium diffusion coefficient in unoxidized IG-110 graphite is independent of concentration within the range 34 – 163 µg Cs/ggraphite. Above this, the effective cesium diffusion coefficient changes with concentration. The diffusion coefficient was increased by a factor of 2–12 in the oxidized set with 7.8% mass loss. These results can be used to aid predictive modeling of cesium diffusion in HTGR cores.

Dynamic characterization of breast cancer response to neoadjuvant therapy using biophysical metrics of spatial proliferation

Current tools to assess breast cancer response to neoadjuvant chemotherapy cannot reliably predict disease eradication, which if possible, could allow early cessation of therapy. In this work, we assessed the ability of an image data-driven mathematical modeling approach for dynamic characterization of breast cancer response to neoadjuvant therapy. We retrospectively analyzed patients enrolled in the I-SPY 2 TRIAL at the Atrium Health Wake Forest Baptist Comprehensive Cancer Center. Patients enrolled on the study received four MR imaging examinations during neoadjuvant therapy with acquisitions at baseline (T0), 3-weeks/early-treatment (T1), 12-weeks/mid-treatment (T2), and completion of therapy prior to surgery (T3). We use a biophysical mathematical model of tumor growth to generate spatial estimates of tumor proliferation to characterize the dynamics of treatment response. Using histogram summary metrics to quantify estimated tumor proliferation maps, we found strong correlation of mathematical model-estimated tumor proliferation with residual cancer burden, with Pearson correlation coefficients ranging from 0.88 and 0.97 between T0 and T2, representing a significant improvement from conventional assessment methods of change in mean apparent diffusion coefficient and functional tumor volume. This data shows the significant promise of imaging-based biophysical mathematical modeling methods for dynamic characterization of patient-specific response to neoadjuvant therapy with correlation to residual disease outcomes.

Random walk diffusion simulations in semi-permeable layered media with varying diffusivity

In this paper we present random walk based solutions to diffusion in semi-permeable layered media with varying diffusivity. We propose a novel transit model for solving the interaction of random walkers with a membrane. This hybrid model is based on treating the membrane permeability and the step change in diffusion coefficient as two interactions separated by an infinitesimally small layer. By conducting an extensive analytical flux analysis, the performance of our hybrid model is compared with a commonly used membrane transit model (reference model). Numerical simulations demonstrate the limitations of the reference model in dealing with step changes in diffusivity and show the capability of the hybrid model to overcome this limitation and to offer substantial gains in computational efficiency. The suitability of both random walk transit models for the application to simulations of diffusion tensor cardiovascular magnetic resonance (DT-CMR) imaging is assessed in a histology-based domain relevant to DT-CMR. In order to demonstrate the usefulness of the new hybrid model for other possible applications, we also consider a larger range of permeabilities beyond those commonly found in biological tissues.

Analysis of Apparent Diffusion Coefficient Value and Dynamic Contrast-Enhanced Magnetic Resonance Imaging Parameters of Prostate Cancer Patients after Diagnosis and Treatment with Magnetic Resonance Imaging.

This research was aimed at exploring the changes in the apparent diffusion coefficient (ADC) and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) parameters of prostate cancer (PCa) patients. Sixty PCa patients from the hospital were recruited as the research object, and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) scans were performed to determine the shape, scope, and enhancement characteristics of prostate lesions and their relationship with surrounding tissues. The quantitative parameters of ADC and DCE-MRI were measured. There were 4 patients (6.67%) with a Gleason score of 6 and 15 patients (25%) with a 4 + 3 score. The ADC with Gleason = 6 is 0.81 ± 0.08 × 10−3 s/mm2, the ADC with Gleason = 3 + 4 is 0.74 ± 0.07 × 10−3 s/mm2, the ADC with Gleason = 4 + 3 is 0.73 ± 0.05 × 10−3 s/mm2, the ADC with Gleason = 9 is 0.65 ± 0.06 × 10−3 s/mm2, and the ADC with Gleason = 10 is 0.59 ± 0.07 × 10−3 s/mm2. As the Gleason score increased, the ADC decreased and the permeation parameter transfer constant increased. When the ADC was combined with the permeability parameter transfer constant, the AUC of Gleason = 6 points and Gleason = 7 points was greatly different (P < 0.05). The 95% CI of the ADC combined permeability parameter transport constant when Gleason = 6 points and Gleason = 7 points was 0.898-0.934, the sensitivity was 75.4%, and the specificity was 86.2%. The ADC value was negatively correlated with Gleason score. The ADC value combined with VTC value has good diagnostic performance in evaluating the invasion of PCa, which is very important for making treatment plan and evaluating prognosis.

Discrimination of gas diffusion state in intact coal and tectonic coal: Model and experiment

As the prediction indexes of gas outbursts, the gas content and gas desorption index K1 of drilling cuttings are affected by the gas diffusion in coal particles. According to the current research results, the steady-state and unsteady-state gas diffusion cannot be excellently defined, which leads to the measurement distortion of prediction indexes of gas outbursts in coal particles. Therefore, a general form of simplified diffusion model (GFSDM) considering steady-state and unsteady-state diffusion was established. And the experimental validation and reliability analysis were carried out. The results show that the fitting accuracy of GFSDM for gas diffusion data and the calculation accuracy of the lost gas amount are both greater than those of the simplified unipore diffusion model and simplified mathematical unsteady-state diffusion model. Then, the discriminant index of gas diffusion state and the boundaries of pure diffusion and pure steady diffusion were determined. Based on the boundaries of pure unsteady diffusion and pure steady diffusion, the gas diffusion state was divided into three zones, namely the ultra-negative unsteady diffusion zone, negative unsteady diffusion zone and positive unsteady diffusion zone. The influence mechanism of gas pressure, particle size and tectonism on the gas diffusion state was discussed. It is found that the main reasons for controlling the change of effective diffusion coefficients with time include the influence of diffusion length, influence of free gas pressure and influence of absorbed gas thickness. The research results can improve the gas diffusion theory and provide a theoretical basis for predicting coal and gas outbursts.

Molecular dynamics simulation of hydrogen diffusion in water-saturated clay minerals; implications for Underground Hydrogen Storage (UHS)

A suitable option for Underground Hydrogen Storage (UHS) is aquifers composed of porous and permeable media. However, the successful execution and long-term safety of the UHS process require further understanding of hydrogen transport behavior in the pathway of caprock to eliminate the possibility of hydrogen leakage. In this regard, we employ Molecular Dynamics simulation to predict the hydrogen diffusion coefficient in five different water-saturated clay minerals, major components of caprock, and to assess the effects of clay mineral characteristics in terms of pore size (1–8 nm), layer charge distribution (octahedral sheet and tetrahedral sheets), and counterion type (Na+ and Ca2+) on hydrogen diffusion. The results show that the diffusion of hydrogen in negatively charged water-saturated clay minerals significantly increases for pore size increments of less than 2 nm (critical pore size) based on layer charge distribution and interlayer cations. However, no considerable changes in the hydrogen diffusion coefficients are observed for pore sizes larger than 2 nm. While the hydrogen diffusion coefficient in pyrophyllite (no charge, no interlayer cation) experiences a monotonous rise as pore size increases. Our findings in this study assist in better experimental test design to examine the possibility of leakage in actual field implementation by focusing on the clay mineral characteristics.

Electron Transfer Kinetics in Ethaline/Water Mixtures: An Apparent Non‐Marcus Behavior in a Deep Eutectic Solvent

AbstractEffects of water on the charge‐transfer (CT) kinetics in deep eutectics solvents (DES) have been investigated in ethaline (1 : 2 choline chloride+ethylene glycol), taken as a prototypical example of a hydrophilic DES. Standard heterogeneous CT rate constants ks were measured for two redox couples: 1,1’‐ferrocene‐dimethanol/1,1’‐ferrocenium‐dimethanol and ferro‐/ferricyanide on a glassy carbon electrode in ethaline as function of the water amount in the DES. Contrarily to the behavior reported in classical solvents and in apparent contradiction with the Marcus Theory, ks values show very little or no variation with the amount of water in the DES or the changes of viscosities or diffusion coefficients that are observed. This unexpected phenomenon is discussed as function of the known physical‐chemistry parameters of ethaline.