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Results for “interfacial resistance”

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PubMed1977

Dissolution rates of model gallstones in human and animal biles and importance of interfacial resistance.

Cholesterol monohydrate dissolution kinetics in human gallbladder bile were studied to determine the magnitudes of the in vitro dissolution rates, the rate resistances in human gallbladder bile, and the extent that the interfacial resistance is the rate-determining factor. Dissolution rate studies also were conducted using human duodenal bile and animal bile for comparison. The dissolution rate resistance, R, ranged from 10(4) sec/cm for chicken bile to 10(4)-10(6) sec/cm for human bile. Interfacial resistance was the rate-determining factor for essentially all results. Where chemical composition data were obtained, the R values for the human bile samples were consistent with predictions made from the simulated bile studies. In two human gallbladder specimens having low bile acid-lecithin molar ratios (i.e., 2.9 and 2.3), very high R values of 1.9 X 10(5) and 4.1 X 10(5) sec/cm were found. These values were in good agreement with the findings in the simulated bile studies and suggest that stone dissolution in patients with low bile acid-lecithin ratios may proceed very slowly, even when the bile is highly undersaturated with respect to cholesterol.

Animals↗

PubMed2026

Direct Modeling of the Interfacial Resistance in All-Solid-State Battery.

Interfacial reconstruction and its associated high resistance govern the performance of all-solid-state batteries (ASSBs). However, indirectly inferring interfacial potentials from bulk band alignments masks the true solid-solid electrochemistry, causing orders-of-magnitude discrepancies in predicting space-charge layer (SCL) resistances and impeding interface screening. Herein, by traversing 310 distinct interfaces from ∼29,000 literatures, we develop a non-empirical numerical procedure that directly maps lithium‑ion redistribution to interfacial resistance by integrating ligand‑field theory with the SCL model. Considering electric potential differences and intrinsic carrier properties during interfacial reconstruction via a modified ligand-field splitting strength (MLFSS) descriptor yields unprecedented bridging between modeling and measurement, reducing predicted resistance discrepancies from over ten orders of magnitude to within two. On this basis, we resolve the highly system-dependent controversy over oxide interfacial resistances by identifying extreme MLFSS disparities (>3.5 eV) as the decisive factor, while emphasizing ion‑intercalation sulfides (<0.2 eV) as cathodes for their intrinsic SCL suppression. The predictive capability of this tunable criterion is validated in an all-sulfide V0.5Cr1.5S4/Li10GeP2S12/75% Li2S-24% P2S5-1% P2O5/Li prototype. The resulting ultralow interfacial resistance of 8.8 Ω cm2 ensures superior cycling stability at an active-material energy density of 562 Wh kg-1, establishing a practical paradigm for breaking the energy and kinetics trade-off in ASSBs.

all‐solid‐state battery↗

PubMed1978

Dissolution kinetics of cholesterol in simulated bile II: influence of simulated bile composition.

Normal human gallbladder bile and gallbladder bile of patients undergoing chenodeoxycholic acid therapy were simulated by using appropriate combinations of taurine and glycine conjugates of cholic, chenodeoxycholic, and deoxycholic acids. Also, the total bile acid concentration and the total bile acid to lecithin ratio were varied over physiological ranges. Dissolution rates of cholesterol monohydrate pellets (model gallstone) in these solutions were 90--99% interfacially controlled. Even under conditions favorable for dissolution, i.e., high bile acid concentration and high bile acid to lecithin ratio, the interfacial resistances were extremely large. These results are of the same order of magnitude as those found in the limited studies with actual gallbladder bile and suggest that the bile acids, lecithin, and the electrolytes are the primary determinants of the interfacial resistance for cholesterol dissolution. Furthermore, the kinetics of dissolution were always much faster with the chenodeoxycholic acid-rich compositions than with the corresponding normal compositions. This finding suggests, therefore, that in addition to desaturating bile with respect to cholesterol, the feeding of chenodeoxycholic acid further facilitates cholesterol gallstone dissolution by reducing the interfacial resistance of the process.

Bile↗

PubMed2024

Micro-interfacial behavior of antibiotic-resistant bacteria and antibiotic resistance genes in the soil environment: A review.

Overutilization and misuse of antibiotics in recent decades markedly intensified the rapid proliferation and diffusion of antibiotic resistance genes (ARGs) within the environment, thereby elevating ARGs to the status of a global public health crisis. Recognizing that soil acts as a critical reservoir for ARGs, environmental researchers have made great progress in exploring the sources, distribution, and spread of ARGs in soil. However, the microscopic state and micro-interfacial behavior of ARGs in soil remains inadequately understood. In this study, we reviewed the micro-interfacial behaviors of antibiotic-resistant bacteria (ARB) in soil and porous media, predominantly including migration-deposition, adsorption, and biofilm formation. Meanwhile, adsorption, proliferation, and degradation were identified as the primary micro-interfacial behaviors of ARGs in the soil, with component of soil serving as significant determinant. Our work contributes to the further comprehension of the microstates and processes of ARB and ARGs in the soil environments and offers a theoretical foundation for managing and mitigating the risks associated with ARG contamination.

Soil Microbiology↗

PubMed1979

Effects of mucosal lanthanum on electrical parameters of isolated frog skin. Mechanism of action.

The effect of mucosal La3+ on electrical parameters of isolated frog skins was studied on isolated frog skins with normally polarized or depolarized apical membrane. La3+ increases R8, the paracellular or shunt resistance and diminishes RNa, the resistance of the active sodium path, in both polarized and depolarized skins. The stimulatory effect of La3+ on short-circuit current (Is.c.) is correlated with this decrease in RNa. The characteristics of the stimulatory effect are: very rapid onset, ionic strength dependency, the possibility of being elicited by many other ions besides La3+. These features allow us to postulate that La3+ might affect the external interfacial potential which in turn affects the resistance of the sodium path.

Animals↗

PubMed1977

Some biophysical and biochemical properties of poly(phthaloyl L-lysine) microcapsules containing hemolysate.

Measurements of oxygen equilibrium, zeta-potential, resistance to flow, carbonic anhydrase activity, and catalase activity were made on sheep erythrocyte hemolysate-loaded poly(phthaloyl L-lysine) microcapsules (artificial red blood cells) prepared by an interfacial polycondensation technique. The measurements revealed that oxygen dissociation equilibrium, zeta-potential, and carbonic anhydrase activity of the microcapsules are almost the same as those of sheep erythrocytes, while the microcapsules have a higher resistance to flow and a lower catalase activity than the erythrocytes. Possible ways of improving the properties of the microcapsules were suggested.

Animals↗

PubMed2026

Genomic and structural insights into the atpB L173I substitution: modulation of the F₀ rotor architecture in Mycobacterium tuberculosis ATP synthase and altered Bedaquiline binding dynamics.

The F₀F₁ ATP synthase of Mycobacterium tuberculosis (M. tuberculosis) is an essential membrane-embedded rotary motor responsible for ATP synthesis and maintenance of the proton motive force in bacteria. The transmembrane F₀ domain comprises the c-subunit (atpE) and the a-subunit (atpB). Their coordinated interactions are needed for proton translocation and torque generation. Bedaquiline (BDQ), FDA-approved diarylquinoline for the treatment of multidrug-resistant tuberculosis (MDR-TB), targets the F₀ motor by binding at the a-c interface and inhibiting rotary catalysis. To the best of our knowledge, this study represents the first attempt to analyze the effects of mutations in the atpB protein on its structural stability in the F₀ domain, thereby highlighting the novelty of this work. In this study, we integrated Indian whole-genome sequencing (WGS) datasets (PRJNA37907) with long-timescale (1000 ns) membrane-embedded molecular dynamics (MD) simulations. Among 57 atpB mutations identified from WGS analysis, L173I was selected for structural and MD analysis. L173I is located at the atpB-atpE interface near the BDQ-binding region, despite V177L and S184A showing higher prevalence. Comparative MD simulations encompassed four systems: wild-type apo, wild-type with BDQ, L173I apo, and L173I with BDQ. Structural interrogation revealed that the L173I substitution induces subtle destabilization of the global fold of the atpB-atpE complex relative to the apo state, while more critically attenuating inter-subunit contacts between the a-subunit and the c-ring. These perturbations provide a mechanistic rationale for reduced BDQ susceptibility, arising from altered interfacial dynamics rather than complete abrogation of drug binding. This integrative genomic-structural framework advances our understanding of ATP synthase-mediated resistance in M. tuberculosis.

Diarylquinolines↗

PubMed1977

Umbilical vascular compliance in sheep.

To explore the mechanical properties of umbilical vessels and to test for possible interactions between maternal and fetal circulations, we recorded pressure-volume curves from isolated in situ placentas of 17 sheep. We estimated static umbilical compliance by extrapolating to infinitely slow rates of volume change. We found that compliance averaged .231 +/- .014 SE ml/mmHg per kg fetal wt under control conditions, a value that increased 26.5% when maternal arterial pressure was lowered 85 mmHg (clamping the aorta), but did not change when venous pressure was raised 37 mmHg (clamping IVC). After replacing blood with kerosene which does not penetrate small vessels because of interfacial tension, we found arteries accounted for 22% and veins for 41% of total compliance, leaving 37% attributable to small placental vessels and surrounding tissue. We conclude that umbilical vessels are about one-half as compliant as adult vessels on a body-weight basis, but only slightly less compliant than vessels elsewhere in the fetal body. When maternal vessels expand they interact with surrounding placental tissue, displacing fetal blood and altering the apparent compliance of umbilical vessels.

Animals↗