Gap Formation Research Articles

Pathophysiological Mechanisms of the Onset, Development, and Disappearance Phases of Skin Eruptions in Chronic Spontaneous Urticaria.

Chronic spontaneous urticaria (CSU) is a typical example of an intractable skin disease with no clear cause and significantly affects daily life of patients. Because CSU is a human-specific disease and lacks proper animal model, there are many questions regarding its pathophysiological dynamics. On the other hand, most clinical symptoms of urticaria are notable as dynamic appearance of skin eruptions called wheals. In this study, we explored dynamics of wheal by dividing it into three phases using a mathematical model: onset, development, and disappearance. Our results suggest that CSU onset is critically associated with endovascular dynamics triggered by basophils positive feedback. In contrast, the development phase is regulated by mast cell dynamics via vascular gap formation. We also suggest a disappearance mechanism of skin eruptions in CSU through an extension of the mathematical model using qualitative and quantitative comparisons of wheal expansion data of real patients with urticaria. Our results suggest that the wheal dynamics of the three phases and CSU development are hierarchically related to endovascular and extravascular pathophysiological networks.

Cyclic stretch regulates epithelial cell migration in a frequency dependent manner via intercellular vinculin recruitment

The epithelial microenvironment is incredibly dynamic, subjected to mechanical cues including cyclic stretch. While cyclic cell stretching platforms have revealed epithelial cell reorientation and gap formation, few studies have investigated the long-term effects of cyclic stretch on cell migration. We measured the migratory response of the epithelium to a range of physiologically relevant frequencies and stretch. Our results indicate that lower stretch frequencies (i.e., 0.1 Hz) suppress epithelial migration, accompanied by cell reorientation and high cell shape solidity. We found that this response is also accompanied by increased recruitment of vinculin to cell-cell contacts, and this recruitment is necessary to suppress cell movements. These results confirm the mechanosensitive nature of vinculin within the adherens junction, but independently reveal a novel mechanism of low frequency stress response in supporting epithelial integrity by suppressing cell migration.

Ultrasound-activated microbubbles mediate F-actin disruptions and endothelial gap formation during sonoporation

Locally opening up the endothelial barrier in a safe and controlled way is beneficial for drug delivery into the extravascular tissue. Although ultrasound-induced microbubble oscillations can affect the endothelial barrier integrity, the mechanism remains unknown. Here we uncover a new role for F-actin in microbubble-mediated endothelial gap formation. Unique simultaneous high-resolution confocal microscopy and ultra-high-speed camera imaging (10 million frames per second) reveal that single oscillating microbubbles (radius 1.3–3.8 μm; n = 48) induce sonoporation in all cells in which F-actin remodeling occurred. F-actin disruption only mainly resulted in tunnel formation (75 %), while F-actin stress fiber severing and recoil mainly resulted in cell-cell contact opening within 15 s upon treatment (54 %) and tunnel formation (15 %). F-actin stress fiber severing occurred when the fibers were within reach of the microbubble's maximum radius during oscillation, requiring normal forces of ≥230 nN. In the absence of F-actin stress fibers, oscillating microbubbles induced F-actin remodeling but no cell-cell contact opening. Together, these findings reveal a novel mechanism of microbubble-mediated transendothelial drug delivery, which associates with the underlying cytoskeletal F-actin organization.

Dust ring and gap formation by gas flow induced by low-mass planets embedded in protoplanetary disks. II. Time-dependent model

The observed dust rings and gaps in protoplanetary disks could be imprints of forming planets. Even low-mass planets in the 1--10 Earth-mass regime, which have not yet carved deep gas gaps, can generate such dust rings and gaps by driving a radially-outward gas flow, as shown in previous work. However, understanding the creation and evolution of these dust structures is challenging due to dust drift and diffusion, requiring an approach beyond previous steady state models. Here we investigate the time evolution of the dust surface density influenced by the planet-induced gas flow based on post-processing three-dimensional hydrodynamical simulations. We find that planets larger than a dimensionless thermal mass of $m=0.05$ corresponding to $0.3$ Earth mass at 1 au or 1.7 Earth masses at 10 au generate dust rings and gaps provided that solids have small Stokes numbers St and that the disk midplane is weakly turbulent ($ diff As dust particles pile up outside the orbit of the planet, the interior gap expands with time when the advective flux dominates over diffusion. Dust gap depths range from a factor of a few to several orders of magnitude, depending on planet mass and the level of midplane particle diffusion. We constructed a semi-analytic model describing the width of the dust ring and gap, and then compared it with the observational data. We find that up to 65<!PCT!> of the observed wide-orbit gaps could be explained as resulting from the presence of a low-mass planet, assuming diff and St However, it is more challenging to explain the observed wide rings, which in our model would require the presence of a population of small particles ($ Further work is needed to explore the role of pebble fragmentation, planet migration, and the effect of multiple planets.

Bragg resonances in left-handed bigyrotropic media based on periodic ferromagnetic semiconductor

In this work, a theoretical model for a periodic bigyrotropic left-handed medium, which is a ferromagnetic semiconductor, is developed. The presence of periodicity in such a structure leads to the formation of Bragg band gaps in the spectrum of propagating waves, both in the microwave and terahertz ranges. Band gaps in the microwave range are formed in the frequency region with double negative effective parameters of the medium. The band gaps density decreases with increasing frequency in the microwave range and increases in the terahertz range.

Investigating the photocatalytic efficacy of a porous cuprous gallate (CuGa2O4) thick film

Abstract The study aimed to investigate the photocatalytic activity of porous copper gallate (CuGa2O4) thick film with significant wall dimensions. The thick film was meticulously fabricated using tape casting systems, with CuGa2O4 nanoparticles synthesized by Sol–Gel technique and subsequently transformed into gels for the tape casting process. Rietveld refinements were employed to elucidate the crystal structure and lattice parameters of the CuGa2O4 spinel oxide lattice. Moreover, electronic energy configurations and optical transmittance measurements were acquired through UV-visible spectrophotometry. The correlations between the crystal structure, band gap change and formation of electronic energy levels in relation to the photocatalytic performance of CuGa2O4 were explored. The comprehensive examination provides valuable insights into the complex interaction between material properties and photocatalytic behavior, offering a nuanced understanding of the potential applications of porous CuGa2O4 thick films in various technological fields.

Comparison of continuity index for drag versus point-by-point ablation with the use of proactive esophageal cooling

Abstract Background Proactive esophageal cooling was recently FDA cleared to reduce the likelihood of esophageal injury during radiofrequency (RF) ablation for treatment of atrial fibrillation (AF). Long-term follow-up data have also shown improved freedom from arrhythmia with proactive esophageal cooling compared to luminal esophageal temperature (LET) monitoring during pulmonary vein isolation (PVI). One hypothesized mechanism is the greater lesion continuity attainable with the use of cooling, which can be quantified by the Continuity Index (which increases as continuity decreases). Increasing the Continuity Index increases gap formation, reduces isolation, and leads to greater AF recurrence; however, the difference in Continuity Index between ablating in a point-by-point fashion versus a dragging fashion has not previously been analyzed. Purpose To prospectively measure the Continuity Index of PVI cases and compare the dragging technique to point-by-point technique when using proactive esophageal cooling or LET monitoring. Methods We determined the Continuity Index for 101 patients: 77 prospectively utilizing proactive esophageal cooling, 24 retrospectively recorded using LET monitoring. Cases were completed by four operators, three utilizing point-by-point technique, and one using the drag technique. The Continuity Index was calculated by incrementing one unit for each lesion that did not border the previous lesion during the PVI (simplifying the original description of the Continuity Index). Results For cases using esophageal cooling and performing RF ablation using the drag technique, the average Continuity Index was 8.5 (range: 1 to 14). For point-by-point operators using esophageal cooling, the average Continuity Index was 1.2 (range: 0 to 9), representing a difference of 7.3 between the dragging technique and point-by-point ablation (p < .001). Patients receiving LET monitoring and RF ablation using the drag technique had Continuity Indices of 23.8 (range 15 to 30). Patients receiving LET monitoring and RF ablation using point-by-point ablation had Continuity Indices of 28.4 (range 16 to 50). Figure 1 compares these findings. Only 4 patients (5%) in the esophageal cooling group had a Continuity Index above 6 on either side (all in the dragging group), versus 100% (24) of patients in the LET monitoring group. Conclusion Proactive esophageal cooling during PVI is associated with a high degree of lesion continuity, as represented by the low Continuity Index. The drag technique resulted in a higher index than the point-by-point technique, but both provided significantly lower Continuity Indices (greater lesion continuity) than cases using LET monitoring. This may offer a mechanism for the greater freedom from arrhythmia seen to date with proactive cooling in long-term follow-up.Figure 1.Comparison of Continuity Index

Impact of oxidized low-density lipoprotein on rat liver sinusoidal endothelial cell morphology and function

Atherogenesis is associated with elevated plasma levels of oxidized low-density lipoproteins (oxLDL). In vivo, oxLDL causes liver endothelial swelling, and disrupts liver sinusoidal endothelial cell (LSECs) fenestrations. We mapped the nanoscale kinetics of these changes in vitro in isolated rat LSECs challenged with oxLDL and monitored viability with endocytosis and cytotoxicity assays. OxLDL disrupted LSEC ultrastructure – increasing oxLDL concentrations and oxidation levels caused sieve plate loss, fenestration fusion, and gap formation. Importantly, these effects were not uniform across all LSECs. LSECs retained the ability to endocytose ligands irrespective of the presence of oxLDL. However, increasing oxidation levels and concentrations of oxLDL inhibited LSEC mediated degradation of endocytosed ligands. Viability was unaffected by any oxLDL challenge. In conclusion, oxLDL disrupts LSEC ultrastructural morphology in vitro but LSECs remain viable and mostly maintain the scavenging function during oxLDL challenge.

SNF2L suppresses nascent DNA gap formation to promote DNA synthesis.

Nucleosome remodelers at replication forks function in the assembly and maturation of chromatin post DNA synthesis. The ISWI chromatin remodeler SNF2L (or SMARCA1) travels with replication forks but its contribution to DNA replication remains largely unknown. We find that fork elongation is curtailed when SNF2L is absent. SNF2L deficiency elevates replication stress and causes fork collapse due to remodeling activities by fork reversal enzymes. Mechanistically, SNF2L regulates nucleosome assembly to suppress post-replicative ssDNA gap accumulation. Gap induction is not dependent on fork remodeling and PRIMPOL. Instead, gap synthesis is driven by MRE11 and EXO1 indicating susceptibility of nascent DNA to nucleolytic cleavage and resection when SNF2L is removed. Additionally, nucleosome remodeling by SNF2L protects nascent chromatin from MNase digestion and gap induction highlighting a critical role of SNF2L in chromatin assembly post DNA synthesis to maintain unperturbed replication.

Rhizosheath Formation and Its Role in Plant Adaptation to Abiotic Stress

The rhizosheath, the layer of soil tightly attached to the roots, protects plants against abiotic stress and other adverse conditions by providing a bridge from the plant root system to the soil. It reduces the formation of air gaps between the root and soil and facilitates the transportation of water at the root–soil interface. It also serves as a favourable niche for plant-growth-promoting rhizobacteria in the surrounding soil, which facilitate the absorption of soil water and nutrients. This review compares the difference between the rhizosheath and rhizosphere, and summarises the molecular and physiological mechanisms of rhizosheath formation, and identifying the causes of rhizosheath formation/non-formation in plants. We summarise the chemical and physical factors (root hair, soil-related factors, root exudates, and microorganisms) that determine rhizosheath formation, and focus on the important functions of the rhizosheath in plants under abiotic stress, especially in drought stress, phosphorus deficiency, aluminium stress, and salinity stress. Understanding the roles played by the rhizosheath and the mechanisms of its formation provides new perspectives for improving plant stress tolerance in the field, which will mitigate the increasing environmental stress conditions associated with on-going global climate change.

Tunable wave coupling in periodically rotated Miura-ori tubes.

Origami folding structures are vital in shaping programmable mechanical material properties. Of particular note, tunable dynamical properties of elastic wave propagation in origami structures have been reported. Despite the promising features of origami metamaterials, the influence of the kinematics of tessellated origami structures on elastic wave propagation remain unexplored. This study proposes elastic metamaterials using connected Miura-ori tubes, the kinematics of which are coupled by folding and unfolding motions in a tubular axis; achieved by periodically connecting non-rotated and rotated Miura-ori tubes. The kinematics generate wave modes with localized deformations within the unit cell of the metamaterials, affecting the global elastic deformation of Miura-ori tubes via the coupling of wave modes. Dispersion analysis, using the generalized Bloch wave framework based on bar-and-hinge models, verifies the influence of kinematics in the connected tubes on elastic wave propagation. Furthermore, folding the connected tubes changes the coupling strength of wave modes between the kinematics and global elastic deformation of the tubes by breaking the ideal kinematics. The coupling of wave modescontributes to the formation of the band gaps and their tunability. These findings enable adaptive and in situ tunability of band structures to prohibit elastic waves in the desired frequency ranges.This article is part of the theme issue 'Origami/Kirigami-inspired structures: from fundamentals to applications'.

Study on solidification and heat transfer of billet shell in a new-structure high-speed continuous casting mold

In this work, a three-dimensional finite element model of a newly structured high-speed continuous casting mold was established to study the heat transfer and solidification process of the billet shell. A complete billet shell, from the meniscus to the secondary cooling zone, was obtained through flame cutting. Using both simulations and test verification, detailed analyses were conducted on the temperature field distribution, thickness variation law, and cooling rate law of the billet shell within the mold, revealing its solidification behavior. Additionally, the effects of casting speed, molten steel superheat, and mold taper on the solidification behavior of the billet shell were discussed. Results showed that the simulation data were basically consistent with the test verification results. Within 200 mm from the meniscus, the heat dissipation accounted for three-quarters of the mold's total heat dissipation. The cooling rate at the corners of the billet shell was slightly higher than that at the sides. Between 200 mm and 400 mm from the meniscus, air gaps caused the temperature at the corners of the billet shell to rise. Afterwards, the whole billet shell eventually reached a similar the heat dissipation rates. The thickness of the billet shell increased exponentially within 110 mm from the curved meniscus, and from 110 mm to the exit of the mold, the thickness increased linearly but slowly. The effect of molten steel superheat within a range of 10 °C on billet shell solidification was relatively minor. Increasing the casting speed reduced the billet shell thickness and raised the billet shell surface temperature. However, increasing the taper of the mold had the opposite effect. Both adjustments shifted the gap formation position backward.

Existence of forced waves and gap formations for a Lotka-Volterra competition system with nonlocal dispersal in a time periodic shift habitat

This paper is devoted to the study of a class of time periodic Lotka-Volterra competition system with nonlocal dispersal and shifting habitats. By using some known results of the periodic KPP model and employing the iterative techniques, we prove that there exist two positive numbers $c_{0}(d_{1})$ and $c_{0}(d_{2})$ such that the system admits a forced wave provided that the forcing speed $c\in(-c_{0}(d_{2}),c_{0}(d_{1}))$. In addition, based on the theoretical results, we show that the gap formations exist for $c>c_{0}(d_{1})$ and $c<-c_{0}(d_{2})$.

Composite metastructure with tunable ultra-wide low-frequency three-dimensional band gaps for vibration and noise control

Low-frequency vibration and noise control present enduring engineering challenges that garner extensive research attention. Despite numerous active and passive control solutions, achieving multiple ultra-wide attenuation regions remains elusive. Addressing vibration and noise control across a multidirectional broad low-frequency spectrum, three-dimensional metastructures have emerged as innovative solutions. This study introduces a novel three-dimensional composite metastructure featuring multiple ultra-wide three-dimensional complete band gaps. The research emphasizes the design strategy of elastic ligaments to achieve multiple ultra-wide attenuation regions spanning from 0.7 to 40 kHz. The band structures are elucidated through modal analysis and further substantiated by an analytical model based on a spring-mass chain with an additional resonator. The underlying physical mechanism for the formation of multiple ultra-wide band gaps is revealed through novel vibration modes from finite element analyses. Furthermore, we demonstrate that the distribution and the relative width of the ultra-wide band gaps can be tuned by modifying the geometric parameters of the metastructure. Utilizing additive manufacturing, prototypes are fabricated, and low-amplitude vibration tests are conducted to evaluate real-time vibration attenuation properties. Consistency is observed among theoretical, numerical, and experimental results. The proposed structure shows significant potential for high-performance meta-devices aimed at controlling noise and vibration across an extremely wide low-frequency spectrum.

Quantifying the role of electron plateau distribution on the chorus gap formation using one-dimension PIC simulations

Although ubiquitous in the Earth’s inner magnetosphere, how chorus waves with a gap in intensity near half the electron cyclotron frequency, 0.5fce, is formed remains to be understood. One hypothesis invokes the often-observed feature in electron phase space density where two anisotropic populations of warm and hot temperatures, respectively, are separated by a relatively isotropic beam-like component, called the parallel plateau distribution. According to linear theory, its mean velocity is such that the plateau population can lead to a sufficient cyclotron damping in a narrow frequency range near 0.5fce. To test this hypothesis more quantitatively, we carry out a series of one-dimensional particle-in-cell simulations in a parabolic magnetic field with observationally constrained plateau density and mean velocity. We find that even though the chorus generation involves nonlinear physics, the gap formation is largely determined by the linear properties of plateau electrons. In addition, given a sufficiently large plateau density with a right combination of warm and/or hot source populations, our simulations were able to generate lower-band-only chorus, upper-band-only chorus, banded chorus with partial damping at the gap, and banded chorus with a strong power gap. When it comes to comparing with observations, however, we find that (1) the minimum plateau density required to generate banded chorus is somewhat larger than that observed; (2) even with the largest plateau density used, the gap formation in the simulations is not consistent; and (3) most importantly, the dependence of the gap frequency on the plateau velocity in our parametric analysis differs quite substantially from that of the recent statistical results. Provided that the simplifying assumptions in our simulations remain valid, these discrepancies would indicate that the electron plateau distribution is not the major contributor to the chorus gap formation.

Gas dynamics around a Jupiter-mass planet

Context. Giant planets grow and acquire their gas envelope during the disk phase. At the time of the discovery of giant planets in their host disk, it is important to understand the interplay between the host disk and the envelope and circum-planetary disk properties of the planet. Aims. Our aim is to investigate the dynamical and physical structure of the gas in the vicinity of a Jupiter-mass planet and study how protoplanetary disk properties, such as disk mass and viscosity, determine the planetary system as well as the accretion rate inside the planet’s Hill sphere. Methods. We ran global 3D simulations with the grid-based code fargOCA, using a fully radiative equation of state and a dust-to-gas ratio of 0.01. We built a consistent disk structure starting from vertical thermal equilibrium obtained by including stellar irradiation. We then let a gap open with a sequence of phases, whereby we deepened the potential and increased the resolution in the planet’s neighbourhood. We explored three models. The nominal one features a disk with surface density, ∑, corresponding to the minimum mass solar nebula at the planet’s location (5.2 au), characterised by an α viscosity value of 4 10−3 at the planet’s location. The second model has a surface density that is ten times smaller than the nominal one and the same viscosity. In the third model, we also reduced the viscosity value by a factor of 10. Results. During gap formation, giant planets accrete gas inside the Hill sphere from the local reservoir. Gas is heated by compression and cools according to opacity, density, and temperature values. This process determine the thermal energy budget inside the Hill sphere. In the analysis of our disks, we find that the gas flowing into the Hill sphere is approximately scaled as the product ∑ν, as expected from viscous transport. The accretion rate of the planetary system (envelope plus circum-planetary disk) is instead scaled as √Σv, with its efficiency depending on the thermal energy budget inside the Hill sphere. Conclusions. Previous studies have shown that pressure-supported or rotationally supported structures are formed around giant planets, depending on the equation of state (EoS) or on the opacity; namely, on the dust content within the Hill sphere. In the case of a fully radiative EoS and a constant dust to gas ratio of 0.01, we find that low-mass and low-viscosity circum-stellar disks favour the formation of a rotationally supported circum-planetary disk. Gas accretion leading to the doubling time of the planetary system of > 105 years has only been found in the case of a low-viscosity disk.

Wear and Gap formation assessment of thermos-viscous resin composites.

Wear and Gap formation assessment of thermos-viscous resin composites.

Does the femoral component design modified in consideration of Asian anatomical characteristics fit better than the conventional design for Korean femora in reality?

We aimed to investigate the anatomical and clinical advantages of an Asian-specific femoral component design with a high femoral aspect ratio, compared with the conventional femoral component design. A retrospective analysis of the operation and outpatient clinic records of 239 knees operated on using an anatomically modified femoral component design (MFCD, Group A) and 153 knees operated on using a conventional femoral component design (CFCD, Group B) in Korean patients was performed. Three subgroups were created based on the mediolateral size of the two different femoral component designs. The geometric accommodation of each femoral component was assessed using intraoperatively measured femoral posterior condylar resection and posterior condylar trimming amounts. Clinical outcomes were assessed using a range of motion (ROM) and patient-reported outcome measurements. In the comparison between Groups A and B, the mean combined bilateral posterior condylar trimming (XPCT) was 2.91 [2SD: -4.12-9.94] and 1.45 [2SD: -5.89-8.80], and the median XPCT was 3 and 1.5. In the largest subgroup (subgroup 2), Groups A and B included 100 and 112 patients, all six posterior condylar resection and trimming parameters were significantly larger in Group A. Preoperative and postoperative ROM and Hospital for Special Surgery scores were similar between the two groups. Preoperative Western Ontario and McMaster Universities Arthritis Index (WOMAC) was higher in Group A. However, postoperative WOMAC was similar between the groups. Perioperative improvement in WOMAC index was significantly greater in Group B. The Asian-specific femoral component design resulted in more resection and trimming of the femoral posterior condyle than the conventional design despite it was not associated with different clinical outcomes. Surgeons should be aware of unexpected excessive posterior condylar resection and formation of large flexion gap when using femoral component design with high femoral aspect ratio.

Tunnelling-induced nonlinear responses of continuous pipelines resting on tensionless Winkler foundation

Prevailing analytical approaches for tunnelling-induced soil-pipeline interactions predominantly rely on linear analyses, limiting their applicability in nonlinear scenarios. This study introduces a novel tensionless Winkler solution that accounts for gap formation and soil yielding, validated against three well-documented experiments and demonstrating superiority over existing Winkler solutions. Additionally, plate load tests refine traditional soil-bearing theories for buried pipelines in sand, providing subgrade stiffness and ultimate bearing capacity values pertinent to tunnelling-induced interactions. Parametric studies highlight amplified nonlinearity in pipeline behaviours with increased pipeline flexural rigidity and tunnel volume loss, due to soil-pipeline separation and subgrade yielding. Notably, ignoring gap formation and soil yielding leads to overly conservative estimations of pipeline deflections and bending moments. Higher subgrade moduli increase pipeline strains, while enhanced subgrade bearing capacity above the pipeline prevents soil yielding, rendering its effect negligible, whereas the bearing capacity beneath the pipeline is inconsequential in tunnelling scenarios.

A study on radial oil seal leakage failure due to viscoelasticity under dynamic eccentricity

Purpose This study aims to investigate the causes of leakage in radial oil seals under dynamic eccentricity, elucidate the influence of operating parameters on leakage failure and develop methods for predicting and preventing such leakage. Design/methodology/approach Based on the principle of cam motion and considering viscoelasticity, develops a motion model of the compression and release of the shaft seal and proposes a method to determine its failure. In addition, this study quantifies the leakage gap and formulates a quantitative calculation model to accurately determine the location and shape parameters of the leakage gap. Findings Leakage gaps predominantly occur during the release phase of the shaft seal. Their presence can be identified by comparing the descending times of the seal and the shaft during this phase. An increase in rotation speed and eccentricity heightens the likelihood of gap formation, with both the dimensions and leakage rate of the gap increasing as these factors escalate. Eccentricity, in particular, has a more pronounced effect on gap formation. Originality/value This study clarifies the failure mechanisms of radial oil seals under dynamic eccentricity and introduces a criterion for identifying leakage gaps, providing valuable theoretical guidance for the design and optimization of radial oil seals. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-05-2024-0192/.