Permeability Measurements Research Articles

Unique Self-Phosphorylating Polybenzimidazole of the 6F Family for HT-PEM Fuel Cell Application.

High-temperature polymer-electrolyte membrane fuel cells (HT-PEMFCs) are a very important type of fuel cells since they operate at 150-200 °C, making it possible to use hydrogen contaminated with CO. However, the need to improve the stability and other properties of gas-diffusion electrodes still impedes their distribution. Self-supporting anodes based on carbon nanofibers (CNF) are prepared using the electrospinning method from a polyacrylonitrile solution containing zirconium salt, followed by pyrolysis. After the deposition of Pt nanoparticles on the CNF surface, the composite anodes are obtained. A new self-phosphorylating polybenzimidazole of the 6F family is applied to the Pt/CNF surface to improve the triple-phase boundary, gas transport, and proton conductivity of the anode. This polymer coating ensures a continuous interface between the anode and proton-conducting membrane. The polymer is investigated using CO2 adsorption, TGA, DTA, FTIR, GPC, and gas permeability measurements. The anodes are studied using SEM, HAADF STEM, and CV. The operation of the membrane-electrode assembly in the H2/air HT-PEMFC shows that the application of the new PBI of the 6F family with good gas permeability as a coating for the CNF anodes results in an enhancement of HT-PEMFC performance, reaching 500 mW/cm2 at 1.3 A/cm2 (at 180 °C), compared with the previously studied PBI-O-PhT-P polymer.

Assessing seromuscular layer and serosa removal on intestinal permeability measurements in weaned piglet everted sac segments.

The integrity of the intestinal barrier is crucial for regulating the passage of pathogens and toxins, while facilitating nutrient absorption. The everted gut sac technique, an ex-vivo technique, can be used to study interventions on barrier function. This cost-effective approach utilizes relatively large gut segments to study specific intestinal regions. Typically, intact (non-stripped) intestinal segments are used, but their use may underestimate permeability due to the medial positioning of blood vessels relative to the seromuscular layer and serosa. However, removing these layers risks physical damage, resulting in an overestimation of intestinal permeability. Therefore, we investigated the impact of stripping jejunal segments on permeability to fluorescein isothiocyanate-dextran (FITC, 4kDa) and tetramethylrhodamine isothiocyanate-dextran (TRITC, 40kDa), and on the absorption of glucose, lysine, and methionine in jejunal segments from 80 piglets at 8 d postweaning. Piglets were subjected to either high or low sanitary housing conditions and diets provoking intestinal protein fermentation or not, expected to influence intestinal permeability. Stripping of the seromuscular layer and serosa increased the passage of 4kDa FITC-dextran (stripped vs. non-stripped; 1.1 vs. 0.9 pmol/cm2/min, P < 0.001), glucose (40.0 vs. 19.1 pmol/cm2/min, P < 0.001), lysine (2.5 vs. 2.0 nmol/cm2/min, P < 0.001), and methionine (4.1 vs. 2.7 pmol/cm2/min, P < 0.001). As permeability increased, the differences in methionine passage between stripped and non-stripped intestinal segments also increased (slope = 1.30, P = 0.009). The coefficients of variation were comparable between stripped and non-stripped intestines (over all treatments, stripped vs. non-stripped 38% vs. 40%). Stripping, by isolating mucosal processes without introducing additional variation, is thus recommended for studies on intestinal permeability or absorption.

Steady-state two-phase relative permeability measurements in proppant-packed rough-walled fractures

Understanding multiphase flow in fractures filled with minerals and proppants is vital in various subsurface applications. Limited experimental data have led to reliance on correlations lacking physical basis. We conducted experiments to characterize relative permeability in rough-walled fractures packed with unconsolidated porous media. We tested fractures packed with water-wet 40/70 sand (silica) and surface-coated ceramic proppants. Brine and mineral oil were used as the wetting and non-wetting fluid phases, respectively. Steady-state (SS) drainage (non-wetting-phase displacing wetting-phase) and imbibition (wetting-phase displacing non-wetting-phase) tests were performed under a wide range of saturation histories (full-cycle and scanning-curves) to study relative permeability hysteresis of the propped fractures. Every SS drainage or imbibition test consisted of several discrete points at which fluid saturations and the corresponding relative permeability were measured by varying the fractional flow rates of fluids whilst maintaining a constant total flow rate. We analyzed residual non-wetting phase saturations and relative permeability trends to understand two-phase flow behavior in each proppant pack. High-resolution x-ray microtomography was used to understand the pore-scale topology, wettability, and to provide insights about the pore-scale displacement mechanisms involved in this study. The results showed that commonly used models to estimate relative permeabilities of fractures significantly overestimated the SS brine and oil relative permeabilities (denoted as krw and kro) measured in this study. Further analysis unveiled that the kro values during imbibition exceeded their drainage counterparts in both proppants, the ceramic proppant exhibited a lower initial water saturation and a higher end-point kro permeability at the end of the drainage displacement, as well as higher krw across all flooding processes. Updated fitting parameters for a Brooks-Corey-type relative permeability correlation are introduced. This study presents improved insights, extensive experimentally generated relative permeability data, and an updated relative permeability correlation, which can be collectively utilized to reduce uncertainties associated with continuum-scale forecasts of multiphase flow behavior in fractured subsurface formations.

#2055 Variations in free water transport condition ultrafiltration capacity since basal times

Abstract Background and Aims There is great variability in free water carrying capacity (FFWC) in incident patients, but the extent to which this variability impacts inherent ultrafiltration failure (UF) is unknown. The peritoneal equilibration test (PET) with 3.86% glucose allows measurement of permeability (D/Pcr), standard UF (UFs) and sodium screening (CriNa) as an indirect measure of TAL. Our objectives were to determine to what extent variations in free water transport condition a related ultrafiltration failure. To assess, according to the variables studied, whether or not the patient`s comorbidities or anthropometric data influenced our study. Method We conducted a study in 58 incident patients in our hospital between 2009-2023 in which we evaluated D/Pcr, UFs and CriNa in PET -3.86. We recorded the dialysis pattern and daily UF. Results The PET -3.86% results were evaluated (Table 1), showing the clinical and peritoneal transport characteristics of the total patients and the comparison between patients with CriNa lower or higher than the median. The patients with lower CriNa were older and had lower UFs and UFd. We found a correlation between CriNa and UFs (0.39, p = 0.002) and daily UF (0.318, p = 0.05). In the multiple regression analysis, CriNa and D/Pcr maintain the correlation with UFs independently. While only CriNa maintains the correlation with daily UF, despite there being no differences in the use of DPA or icodextrin. Conclusion On analyzing the results, we found that the intrinsic variations of the membrane, in the free water transport capacity, justify part of the ultrafiltration capacity measured both in kinetics and daily ultrafiltration. As for age, we found that the older the patient is, the lower the sodium sieving, at least initially. With this study we emphasize the importance of assessing variations in free water transport capacity using the peritoneal equilibrium test as a tool.

#780 “In vivo” difference in ultrafiltration coefficient between two same membrane dialyzers: bigger surface area accounts for better dialysis outcomes?

Abstract Background and Aims Ultrafiltration coefficient (KUF) is a measure of dialyzer permeability to water, given by manufacturers, and expressed in milliliters/hour/mmHg of pressure gradient. Most dialyzers used at this moment are classified as high-flow as having a KUF &amp;gt;20 mL/h/mmHg. KUF value of a dialyzer is an “in vitro” measure which does not correlate with “in vivo” measure, stated to be 5-30% less than theoretical KUF. According to this statement, we wanted to study differences between theoretical and real KUF of two dialyzers with the same membrane composition and different surface area. For this task, we chose 2 dialyzers of usual use in our dialysis unit: FX CorDiax 1000 and FX CorDiax 80 (®FMC). These dialyzers have a main difference in Surface area: 2.3 and 1.8 m2, respectively, and have a theoretical KUF of 76 and 64 mL/h/mmHg. Also, both dialyzers differ in intern diameter (210 vs 185 µm). Method A prospective, not randomized trial was conducted. Inclusion criteria were patients in chronic dialysis at our center, in postdilutional online hemodiafiltration with a FX1000 dialyzer. All patients were informed and accepted freely signing an informed consentment. On 2 consecutive weeks, the intermediate dialysis session of the week was performed in a DBB-EXA dialysis monitor (®Nikkiso), first with a FX CorDiax 1000 and next week with a FX CorDiax 80, with habitual patient dialysis parameters (240 minutes). Blood tests were taken previous and after the session to evaluate clearance differences between both filters. During the session, pressure and flow data was recorded, with an “in vivo” KUF measurement given by the monitor. Results Dialysis sessions were performed in 12 patients who met inclusion criteria. Data results are shown in Table 1. Significant differences between FX CorDiax 1000 and FX CorDiax 80 were observed in prefilter pressure (p 0.008), convective volume (p 0.034), prolactin reduction ratio (p 0.012), “in vivo” KUF/ “in vitro” KUF ratio (p 0.002). “In vivo” KUF graphic given by the monitor showed a logarithmic function curve, with a stabilization between the 2nd and 3rd hour of the session. Conclusion In our study, measurement of “in vivo” KUF by Nikkiso monitor showed a slow decrease after 2nd hour of session, probably related with protein cake of membrane pores. “In vivo” KUF measure was approximately a 40-45% of theoretical value given by manufacturer. The “in vivo” KUF/ “in vitro” KUF ratio was higher for the smaller dialyzer, which probably means a higher optimization of its surface area with usual dialysis sessions. Convective volume and prolactin reduction ratio, as parameters of dialysis efficacy, are higher in the dialyzer with higher surface area and inner intern diameter.

METHODOLOGY AND FEATURES OF RESEARCH OF FILTRATION PROPERTIES OF COMPACTED DEEP-SEATED ROCKS

As a result of the depletion of conventional hydrocarbon reserves, there is a need to explore deposits at great depths and under difficult geological conditions. This requires the improvement of technologies for studying rocks and fluids using computer modeling systems and laboratory equipment. Laboratory modeling of the processes occurring in rocks during drilling, development, stimulation or various chemical treatments plays a significant role in modern hydrocarbon production, as it reduces the number of errors at the design stage of field development or methods of impacting productive formations. There are a number of well-known manufacturers of laboratory equipment that model filtration processes in rocks, but any system has both advantages and disadvantages. To implement the tasks of studying filtration processes in rocks, technologies for the development of compacted and conventional reservoirs, stimulation methods and physical and chemical effects in hydrocarbon production, filtration equipment has been developed that allows for standard and special studies of rock core material. The first low-pressure unit allows for fast and accurate measurements of porosity and permeability at pressures up to 10 MPa and temperatures up to 120℃. In addition to filtration processes, the equipment allows for evaluation studies of the impact of various chemical solutions, drilling and other process fluids on natural and artificial cores in scientific and industrial research. For the study of rocks and fluids in reservoir conditions, a filtration system has been developed that allows for all of the above studies at pressures up to 100 MPa and temperatures up to 200℃. The peculiarity of the developed equipment is high accuracy of measurements, automation of monitoring processes, corrosion-resistant design of the main components and assemblies, which allows conducting research in any aggressive environment. Laboratory studies allow avoiding mistakes in the design of new areas development, reducing drilling accidents and selecting effective technologies for rock impact.

Morphological Study before and after Thermal Treatment of Polymer-Polymer Mixed-Matrix Membranes for Gas Separations.

A good integration of the polymer materials that form a mixed-matrix membrane (MMM) for gas separation is essential to reaching interesting permselective properties. In this work, a porous polymer network (PPN), obtained by combining triptycene and trifluoroacetophenone, has been used as a filler, which was blended with two o-hydroxypolyamides (HPAs) that act as polymer matrices. These polymer matrices have been thermally treated to induce a thermal rearrangement (TR) of the HPAs to polybenzoxazoles (β-TR-PBOs) through a solid-state reaction. For its structural study, various techniques have been proposed that allow us to undertake a morphological investigation into the integration of these materials. To access the internal structure of the MMMs, three different methods were used: a polishing process for the material surface, the partial dissolution of the polymer matrix, or argon plasma etching. The argon plasma technique has not only revealed its potential to visualize the internal structure of these materials; it has also been proven to allow for the transformation of their permselective properties. Force modulation and phase contrast in lift-mode techniques, along with the topographic images obtained via the tapping mode using a scanning probe microscope (SPM), have allowed us to study the distribution of the filler particles and the interaction of the polymer and the filler. The morphological information obtained via SPM, along with that of other more commonly used techniques (SEM, TGA, DSC, FTIR, WASX, gas adsorption, and permeability measurements), has allowed us to postulate the most probable structural configuration in this type of system.

Resonant cavity method based on RF measurement and simulation for measuring complex permittivity or permeability of RF absorbing materials

Accurate measurement of complex permittivity and/or permeability of radio-frequency (RF) absorbing materials is essential to predict the performances of higher-order-mode damping in damped accelerating cavities or in vacuum chambers. We propose an improved resonant cavity method that can be used as a complement to the widely used Nicolson–Ross–Weir method for measuring the RF characteristics of materials. The conventional resonant cavity method is based on the cavity perturbation theory. However, the measurements are inaccurate when losses in the materials are large. The improved method we propose determines the complex permittivity or permeability of materials from the measured resonant frequencies and Q factors based on eigenmode simulations. Because the reliability on the eigenmode calculation for RF cavities with lossy materials has become sufficiently reliable, determination of complex permittivity and permeability can be achieved using such a simulation software. We demonstrate this method using ferrite HF70 (TDK Corp.), which is useful for RF absorbers in damped accelerating cavities or in vacuum chambers.

Ameliorating carbon capture efficiency of polysulfone membranes via collegial incorporation of zeolite imidazole frameworks and carbon nanotubes

AbstractContinuously exacerbating situation of global warming can be effectively mitigated by controlling carbon emissions from combustion processes through economically attractive membrane technology. Carbon capture efficiency of prospective membranes can be significantly improved via synergistically incorporating CO2‐selective ZIF‐300 nanoparticles and carbon nanotubes (CNTs) into polysulfone (PSF) matrix. Solution‐casting coupled with phase‐inversion processes were employed to concoct hybrid membranes containing varying loadings of both nanofillers. Manufactured composite membranes showed improved matrix structure, uniform nanofillers scattering, enhanced thermal resistance, and ameliorated nanofillers‐polysulfone interfacial adhesion as evidenced by morphological and thermal analysis. Both sorption and permeation measurements for CO2 and N2 gases performed on created membranes indicated upgraded CO2 permeability and CO2/N2 permselectivity on account of collegial impact of added nanofillers. In contrast to pristine polysulfone membrane rendering CO2 intake of 4.1 and CO2/N2 sorption selectivity of 12, hybrid membrane containing 15% ZIF‐300 and 3% CNTs uplifted corresponding values to 12 and 22, respectively. As compared to unadulterated polysulfone membrane, CO2 permeability and CO2/N2 permselectivity of hybrid membrane doped with optimized nanofillers loading of were, respectively, elevated by five‐ and three‐folds. Unique features of manufactured membranes can best be manifested in terms of their ability to maintain gas separation performance from post‐combustion effluents.

Estimation of mixed-gas selectivity of membranes using the linear friction-based model

The development of analytical models for predicting the transport properties of membranes in the separation of multicomponent mixtures is highly relevant because (1) measurements of permeability and sorption of gas mixtures in membrane materials are laborious and time-consuming, and (2) estimation of transport properties based on pure gas measurements is desirable, however, rather unreliable and can lead to serious errors. In this paper, within the framework of the well-known frictional-coefficient formalism, we present nonlinear equations for the fluxes of gas mixture components through the membrane, which take into account the diffusional coupling of the fluxes compared to independent gas transport. As a result, an analytical equation for the mixed-gas selectivity was obtained. This equation has an implicit form, which is not quite convenient for practical application, since it has to be solved numerically. A simple explicit expression for mixed gas selectivity was derived using the so-called linear transport model, which is a linearized version of the original nonlinear flux equations. It is important to emphasize that a comparison of the linear model with the formally more rigorous nonlinear model showed only minor quantitative differences. The input parameters for the model are the single gas transport parameters. Testing the linear model using experimental data for the separation of hydrocarbons (n-butane/methane, n-butane/i-butane, propylene/propane) revealed an acceptable fit. A comparison of the model with recent experimental data on the separation of CO2-containing mixtures using microporous polymers is also presented. It is found that the calculated CO2/N2 mixed gas selectivity is in good agreement with the experimental data, while only a semi-quantitative agreement is observed for the CO2/CH4 separation. Besides, it is shown that the model developed for binary gas separation can be extended to ternary gas mixtures.

Poly(vinyl chloride)-based advanced polymer inclusion membranes with Aliquat 336 and inorganic filler for efficient Cr(VI) removal

Poly(vinyl chloride) (PVC) hybrid polymer inclusion membranes (PIMs) with an ion carrier (Aliquat 336) and containing an inorganic filler (Cloisite (CNa) or mica) are successfully elaborated. The filler nature and its content in the PIM composition are optimized in terms of the PIM stability and reuse. It is found that the filler presence in the PVC matrix provokes a more irregular surface and an internal structure with apparent microvoids. Tensile tests reveal two different mechanical behaviors according to the filler type – a drop in Young’s modulus (up to ∼ 51 MPa) observed for membranes containing mica, thus resulting in more flexible membranes; on the contrary, membranes with decreased flexibility are obtained in the CNa presence. The higher Cr(VI) permeability of mica-based PIMs (∼9 µmol/(m2·s)) is attributed to their porous structure and high flexibility. During 5 cycles of Cr(VI) permeation measurements, membrane based on mica and Aliquat 336 preserves its stability, while the transport performance of both unfilled membrane and PIM with CNa is deteriorated. It is also noted that the carrier percolation threshold strongly affects the membrane stability – the lower is the percolation threshold, the higher is the membrane reusability, which is explained by the high stability of mica-based PIMs. This result testifies to the possibility of using hybrid PIMs loaded with mica and containing Aliquat 336 for metal ions separation.

Characterization and synthesis of high permeance SSZ-13 membranes to separate CO2 from CH4 for biogas upgrading

Small-pore zeolites, such as CHA (0.38 nm), have pores that are comparable to the size of CH4 but larger than the size of CO2. As a result of the combination of diffusion and adsorption, these membranes are projected to have strong CO2/CH4 selectivity and CO2 permeance. During this work, SSZ-13 CHA membranes were synthesized, evaluated, and characterized by X-ray Diffraction, Field-Emission Scanning Electron Microscopy, Energy-Dispersive X-ray Spectroscopy, Fourier Transform Infrared Spectroscopy, Solid-State Nuclear Magnetic Resonance, and Thermogravimetric Analysis. Synthesized membranes on the inner surface of single channel alumina supports with a pore size of 200 nm and a length of 105 mm and an active membrane area of ∼17 cm2 showed an ideal permselectivity for CO2/CH4 of 122 (in the single gas permeation measurement) and a CO2 permeance of 36.1 × 10−7 [mol/(m2 s Pa)] and CO2/CH4 selectivity of 173 and a CO2 permeance of 6.5 × 10−7 [mol/(m2 s Pa)] for equimolar CO2 − CH4 mixture. According to the results, the membranes are capable of separating CO2 from natural gas and upgrading biogas for industrial purposes.

PSIII-4 Evaluating the variability of the dual sugar absorption test as a measure of intestinal permeability in pigs

Abstract The intestinal barrier of pigs can be compromised by many factors including health challenges, off-feed events, and environmental stressors. If dysregulated barrier function is caught early, proper treatment can be initiated to potentially prevent more severe complications to overall health. However, there are few procedures to measure intestinal function in pigs that are both validated, sensitive, and minimally invasive. In this research, the dual sugar test using lactulose and mannitol was conducted on a total of 534 pigs of varying age, sex, body weight (BW), and health status. Each pig received the same oral dose of 500 mg/kg body weight lactulose and 50 mg/kg BW mannitol, and blood was collected either 60 or 240 min following the dose. Plasma concentrations of lactulose and mannitol were quantified by high performance liquid chromatography using validated methods. The ratio of lactulose to mannitol absorption (L:M) served as the indicator of barrier function such that a larger L:M ratio was indicative of greater intestinal permeability. In these pigs, L:M ratios ranged from 0 to 6.96. The median L:M ratio was 0.41 while the average was 0.70, indicating that the distribution of the data was right skewed, influenced by 21.0% of pigs exhibiting a L:M of 0. Collecting blood sooner after oral gavage yielded better detectability as only 2.71% of L:M in pigs from the 60 min group was 0 compared with 43.5% from the 240 min group. Ostensibly, an L:M ratio of 0 is biologically relevant, but interpretation of such values is challenging both from statistical and biological perspectives. Intestinal barrier permeability, absorption kinetics between pigs, and delivery efficiency of the L:M solution may all affect lactulose absorption yielding a ratio of 0. In general, the data werewere highly variable, with a standard deviation of 0.95, so a regression analysis was performed to determine which factors may be influencing this variation. Neither a forward nor a backward elimination model determined any of the five explanatory variables (i.e., BW, timing of blood collection, health status, age, or sex) to be significant. Additional correlational analyses further confirmed that there were no significant interactions. Overall, it appears that these factors do not help to explain the variability in the L:M ratio. Further investigation is warranted to validate this process and understand the source and impact of L:M ratios equaling 0.

New test rig for biaxial and plane strain states on uniaxial testing machines

The increasing interest in hydrogen technology and storage systems has also significant influence on material characterization. Storage solutions such as cryo-compressed hydrogen (CcH2) or compressed gaseous hydrogen (CGH2) use high pressure to improve the energy density. The pressurized hydrogen is stored in a pressure vessel. This leads to various strain states in the vessel, which are difficult to reproduce with standard testing equipment, such as a uniaxial testing machine. This contribution presents a new test rig for uniaxial testing machines that is able to generate a biaxial load on a cruciform specimen. A hinged structure converts the uniaxial load into a biaxial load. Different attachments allow both equi-biaxial and plane strain states. In addition, the test rig provides access to both sides of the specimen, extending the possibilities for testing under load, such as optical measurement, specimen cooling or permeability measurement. Finally, experiments show the functionality of the test rig and the desired strain states in the specimen.

Experimental investigation of sandy soil stabilization using chitosan biopolymer

The performance of an environmentally friendly biopolymer synthesised from secondary resources to overcome the wind erosion of sandy soil was investigated in this study. The study employed a multi-scale approach to investigate the mechanical, erosional, and hydraulic properties of sandy soil. At the macroscale, experimental techniques such as unconfined and triaxial compression tests, permeability measurements, contact angle assessments, and wind tunnel experiments were utilized to characterize the bulk behavior of the soil. Concurrently, molecular dynamics (MD) simulations were conducted at the nanoscale to predict surface mechanical characteristics and elucidate chemical interactions at the molecular level. Results show that when the outer surface of the sandy particles is coated with a sparse concentration of biopolymer, the sandy aerosol inhibitory performance is significant even under extreme storm conditions reaching speeds of 140 km/h of storms. The study on the impact of biopolymer content, curing time, and curing conditions revealed that the addition of chitosan biopolymer has the ability to enhance the bonding between particles and significantly enhance the mechanical properties of sandy soil. The atomic insight from molecular dynamics reveals huge entanglement between sandy particles and biopolymer by Van der Waals interaction. The results of the Unconfined Compressive Strength test indicate that chitosan enhances the compressive strength of sand by up to 320 kPa. Additionally, the triaxial test demonstrated that the application of chitosan led to a 34.2 kPa improvement in the cohesion of sand. Furthermore, analysis of the permeability test results revealed a decrease in the hydraulic conductivity coefficient from 1.6 × 10^-6 m/s to 5.7 × 10^-7 m/s, representing a reduction of approximately 35 %.

Mitochondrial function in lungs of rats with different susceptibilities to hyperoxia-induced Acute Respiratory Distress Syndrome (ARDS)

Objective: Rat exposure to hyperoxia is a well-established model of human ARDS. Adult rats exposed to hyperoxia (100% O2) die from respiratory failure within 60-72 hours. However, rats preconditioned by exposure to &gt;95% O2 for 48 hrs followed by a 24-hr “rest period” in room air (H-T) acquire tolerance of the otherwise lethal effects of exposure to 100% O2. In contrast, rats preconditioned by exposure to 60% O2 for 7 days (H-S) become more susceptible to 100% O2. The objective was to evaluate lung tissue mitochondrial bioenergetics in H-T and H-S rats. Methods: Adult rats were exposed to room air (normoxia), &gt;95% O2 for 48 hrs followed by exposure to room air for 24 hrs (H-T), or 60% O2 for 7 days (H-S). Mitochondria were isolated from lung tissue and used to assess mitochondrial bioenergetics. Expressions of electron transport chain complexes were measured in lung tissue homogenate using western blot. Isolated perfused lungs (IPL) were used to determine pulmonary vascular endothelial filtration coeffcient ( Kf) as a measure of pulmonary vascular permeability, and lung tissue mitochondrial membrane potential (ΔΨm). Results: Western blot shows decreased (38%) complex I expression, but increased (70%) complex V expression in H-T lung tissue homogenate compared to normoxia. Complex I expression decreased (43%) in H-S lung tissue homogenate. State 3 oxidative phosphorylation (OxPhos) capacity (Vmax) and respiratory control ratio decreased in mitochondria isolated from H-S lungs. Vmax increased in mitochondria of H-T lungs. Time for ΔΨm repolarization following ADP-stimulated depolarization increased in mitochondria isolated from H-S lungs. IPL studies revealed that tissue ΔΨm is unchanged in H-S and H-T lungs compared to normoxics. Furthermore, complex I plays the dominant role in ΔΨm in H-T and normoxia lungs with no contribution from complex II, whereas complex II has a larger contribution to ΔΨm in H-S lungs than in H-T or normoxia. Kf increased (+178%) in H-S, but not H-T lungs. Discussion: For H-T lungs, decreased complex I expression is countered by increased complex V expression, which could also account for increased Vmax. This along with high tissue glutathione content protects mitochondria from stress such as exposure to 100% O2. For H-S lungs, the effect of decreased complex I expression on lung tissue ΔΨm is countered by a larger contribution from complex II. However, higher dependency of ΔΨm on complex II could lead to higher mitochondrial oxidant production since complex II is the main source of oxidants in rat lungs. This along with decreased Vmax and increased Kf make H-S rats more susceptible to stress such as exposure to 100% O2. These results are clinically relevant since exposure to hyperoxia is a primary therapy for patients with ARDS, and ventilation with 60% O2 is often required for prolonged periods of time, particularly with COVID-19. This study was funded by NHLBI grant 2R15HL129209-03, Department of Veterans Affairs Merit Review Award BX001681, and NSF grant DMS 2153387. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Role of CRF1 and CRF2 Receptors in Stress-induced Increase of Intestinal Epithelial Permeability in the Mouse Colon

Background and Aims: Stress is known to increase intestinal permeability, which may contribute to the development of irritable bowel syndrome (IBS) and other intestinal disorders. Corticotropin releasing factor (CRF) has been proven to mediate stress-induced changes in gut function, such as increased colonic motility, ion secretion, and intestinal permeability. Actions of CRF are mediated by two G-protein coupled receptors, CRF1 and CRF2; both are expressed in the intestine. However, the roles of the CRF1 and CRF2 receptors in stress-induced increase of intestinal epithelial permeability remain unknown. Methods: Adult male and female C57BL/6 mice were restrained (1h/d) for five consecutive days. The selective CRF1 and CRF2 receptor antagonists were injected intraperitoneally 15 min prior to the restraint stress. Control mice were kept in their home cages without restraint. After the last restraint stress/control session, the proximal colon was removed, and the mucosa/submucosa preparations were dissected and mounted onto the Ussing Chamber System for the measurement of intestinal permeability. Transepithelial resistance (TER) and FITC-inulin (4kD) flux across the colonic epithelium were used as indicators of paracellular permeability. Horseradish peroxidase (HRP, 40kD) flux was used to measure transcellular permeability. Results: Restraint stress did not alter TER or FITC-inulin flux in male mice. Pretreatment with the CRF1 receptor antagonist NBI 27914 or the CRF2 receptor antagonist antisauvagine-30 had no effect on TER or FITC-inulin flux in male mice. In female mice, restraint stress significantly reduced TER and increased FITC-inulin flux in the proximal colon, which were blocked by NBI 27914 but not by antisauvagine-30. Restraint stress significantly increased HRP flux in both male and female mice. In male mice, pretreatment with NBI 27914 significantly reduced stress-evoked increase of HRP flux, while antisauvagine-30 had no effect. In female mice, both NBI 27914 and antisauvagine-30 significantly reduced stress-evoked increase of HRP flux. Conclusions: Stress evokes different changes in epithelial permeability in the proximal colon of male and female mice. In male mice, stress does not influence paracellular permeability but increases transcellular permeability, which is mediated by the CRF1 receptor. In female mice, stress increases both transcellular and paracellular permeability. Stress-induced increase of paracellular permeability was mediated by the CRF1 receptor, but the increased transcellular permeability was mediated by both CRF1 and CRF2 receptors. University of Wisconsin-La Crosse Undergraduate Research Grant (CS and LB). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Prediction Model of Coal Gas Permeability Based on Improved DBO Optimized BP Neural Network.

Accurate measurement of coal gas permeability helps prevent coal gas safety accidents effectively. To predict permeability more accurately, we propose the IDBO-BPNN coal body gas permeability prediction model. This model combines the Improved Dung Beetle algorithm (IDBO) with the BP neural network (BPNN). First, the Sine chaotic mapping, Osprey optimization algorithm, and adaptive T-distribution dynamic selection strategy are integrated to enhance the DBO algorithm and improve its global search capability. Then, IDBO is utilized to optimize the weights and thresholds in BPNN to enhance its prediction accuracy and mitigate the risk of overfitting to some extent. Secondly, based on the influencing factors of gas permeability, effective stress, gas pressure, temperature, and compressive strength, they are chosen as the coupling indicators. The SPSS 27 software is used to analyze the correlation among the indicators using the Pearson correlation coefficient matrix. Additionally, the Kernel Principal Component Analysis (KPCA) is employed to extract the original data. Then, the original data is divided into principal component data for the model input. The prediction results of the IDBO-BPNN model are compared with those of the PSO-BPNN, PSO-LSSVM, PSO-SVM, MPA-BPNN, WOA-SVM, BES-SVM, and DPO-BPNN models. This comparison assesses the capability of KPCA to enhance the accuracy of model predictions and the performance of the IDBO-BPNN model. Finally, the IDBO-BPNN model is tested using data from a coal mine in Shanxi. The results indicate that the predicted outcome closely aligns with the actual value, confirming the reliability and stability of the model. Therefore, the IDBO-BPNN model is better suited for predicting coal gas permeability in academic research writing.

Evaluation and comparison of the effects of a new paste containing 8% L-Arginine and CaCO3 plus KNO3 on dentinal tubules occlusion and dental sensitivity: a randomized, triple blinded clinical trial study

BackgroundDentin hypersensitivity, often occurring after dental treatments or from erosive lesions, is a prevalent patient complaint. This study introduces a paste combining 8% L-arginine, calcium carbonate, and potassium nitrate to evaluate its impact on dentinal tubules occlusion, dentin permeability, and tooth sensitivity.MethodsDentin surfaces from 24 third molars (thickness: 2 mm) were divided into two groups of 12. One received the experimental paste, while the other received a placebo without desensitizer. Permeability and sealing ability were assessed through scanning electron microscopy (SEM) and dentin permeability measurement. The pastes’ effects on hypersensitivity were then examined in a triple-blind, randomized parallel-armed clinical trial with 16 eligible patients. Sensitivity to cold, touch, and spontaneous stimuli was recorded using the VAS scale at various intervals post-treatment. Statistical analysis was conducted using Shapiro-Wilk, Mann-Whitney U, Friedman, and Wilcoxon tests (α = 0.05).ResultsThe permeability test demonstrated a significant reduction in dentin permeability in the experimental group (P = 0.002) compared to the control (P = 0.178). SEM images revealed most dentinal tubules in the intervention samples to be occluded. Clinically, both groups showed a significant decrease in the three types of evaluated sensitivity throughout the study. However, no significant difference in sensitivities between the two groups was observed, with the exception of cold sensitivity at three months post-treatment (P = 0.054).ConclusionThe innovative desensitizing paste featuring 8% L-arginine, calcium carbonate, and potassium nitrate effectively occluded dentinal tubules and reduced dentin permeability. It mitigated immediate and prolonged dentin hypersensitivity to various stimuli, supporting its potential role in managing dentin hypersensitivity.Trial registrationhttp://irct.ir: IRCT20220829055822N1, September 9th, 2022.

Structural Features of the Porous Network of Poly(Urethane) Aerogels via Gas Permeability Measurements.

The permeability for gases through polyurethane (PUR) aerogels prepared from unsorted PUR scraps by means of a recycling technique is measured with a dynamic pressure method. The permeabilities are in the range of 10-15 to 10-13 m2 and thus reflect the pore morphology observed with scanning electron microscopy. The permeability depends on the envelope density and microstructural features of the aerogels and decreases with increasing inner surface area. The comparison of the permeability with the Porod constant, which is obtained independently via small-angle X-ray scattering (SAXS), yields a high consistency with the expected theoretical relationship. However, a calculation of inner surface area based on permeability yields lower results than expected from data based on the established SAXS technique, revealing that the famous Carman-Kozeny law correlates only by trend, which is attributed to additional gas transport through the micro- and mesopores. A possible approach for the correlation of this behavior to the tortuosity is given. Several models accounting for the combined action of viscous flow, Knudsen diffusion, and molecular slip along pore walls are fitted to the experimental data, effectively qualifying the permeability measurement as time-efficient and inexpensive technique for the characterization of structural features ofaerogels.