Symmetric Disk Research Articles

Neonatal epithelial reparative capacity is enhanced by acellular placental extract in porcine models

Necrotizing enterocolitis (NEC) is a devastating condition with a ~30% mortality rate in pre-term, very low birth-weight infants. Premature infants lack vital in utero ingestion of amniotic fluid which accelerates intestinal maturation and reduces inflammation. Therefore, an acellular placental extract (PE) akin to amniotic fluid may be therapeutic for NEC. The objective of this study was to evaluate PE’s capacity to accelerate repair following or prevent the induction of NEC-like injury. We hypothesized that PE would enhance neonatal porcine intestinal epithelial cells’ capacity to repair in vitro and in vivo. NEC was induced in 12 piglets via pre-term cesarean delivery and hyperosmolar formula feeding. Prior to formula feeding, piglets were nil per os or enterally supplemented with PE. Tissue, collected at euthanasia, up to 72H after formula initiation, was evaluated grossly and histologically and with immunohistochemical staining for proliferation (Ki67), stem cell identity (Sox9), and apoptosis (CC3). Numerical outputs were assessed with Kolmogorov-Smirnov testing. PE’s effect on epithelial restitution was assessed with scratch assays performed on confluent monolayers derived from ~1-day old piglet ileum. Monolayers were pre-treated with either actin polymerization inhibitor, Latrunculin A, or a cell cycle inhibitor, hydroxyurea. After scratch, either media or PE in media was applied. Scratch-closure was monitored for 24H; percentage-closure was calculated and analyzed using 2-way ANOVA and Tukey multiple comparison. Scratch-wound leading-edge cells were examined for EdU and Ki67 immunofluorescent positivity which was evaluated using Kolmogorov-Smirnov analysis. Tight junction recovery was assessed using identically derived confluent monolayers grown on Transwell inserts and exposed to hypoxia (18H, 1%O2, 5%CO2). Following hypoxia, PE or media alone was added to the apical chamber. Transepithelial electrical resistance (TEER) was measured every 6-12H for 48H using a symmetrical disc electrode chamber. TEER rate of change was analyzed using a two-way ANOVA. For all analyses, significance was set at p<0.05. In vivo PE administration resulted in reduced gross and histological NEC damage in treated compared to untreated piglets (p=0.02). Ki67 and Sox9 expression increased (p=0.71; p=0.93) and CC3 expression decreased with PE treatment (p=0.65). Evaluation of these markers in additional animals is pending. In vitro, PE expedited scratch wound closure (p<0.05) and expanded proliferative cell number along scratch edges (EdU/DAPI, p<0.05; Ki67+EdU/DAPI, p<0.01). Other analyses are pending. PE application prevented gross NEC development in vivo and accelerated recovery in vitro. NIH #R44HD100243; #T32562967-39806. 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.

Realization of exciton-polariton optical chirality based on strong coupling between intrinsic chiral quasibound states in the continuum and monolayer WS2.

Hybrid quasiparticles produced by the strong interaction between nanostructures and excitons will exhibit optical chirality when one of the coupled components is chiral. Due to the tunability of hybrid states, the coupled system has potential applications in chiral devices and chiral sensing. However, reported chiral materials including chiral molecules and three-dimensional chiral structures in the coupled system limit the application due to the weak chiroptical responses and difficult fabrication, respectively. In this paper, we design chiral quasibound states in the continuum (q-BIC) metasurface by introducing planar symmetry-breaking and z-axis perturbation into an array structure whose unit cell is a C4 rotational symmetric disk. By tuning the polarization state of the eigenmode, a significant chiroptical response is obtained in our q-BIC metasurface. Furthermore, mode splitting is observed not only in the reflection spectrum but also in the circular dichroism (CD) spectrum in the chiral q-BIC and monolayer WS2 strong coupling system, which indicates the realization of the exciton-polariton optical chirality. More importantly, one order of magnitude difference in the reflection to left and right circularly polarized light is achieved resulting in significant CD signals. Our work provides a new strategy to realize the exciton polaritons with significant chiroptical responses, which exhibits promising applications in on-chip chiral devices.

A shadow study for a static dyonic black hole with a global monopole surrounded by perfect fluid

In this paper, we mainly study the shadow and observable features of a dyonic black hole (DBH) with a global monopole surrounded by perfect fluid under various profiles of accretions. We investigate the influence of model parameters on the observational signatures and space-time structure of black holes (BHs). We observe that the value of bps\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$b_{ps}$$\\end{document} increases with the increasing values of α\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\alpha $$\\end{document} and η\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\eta $$\\end{document}, while it decreases with the increasing values of the electromagnetic parameter. We found that the corresponding regions and the observed specific intensities of the direct, lensing and photon ring emissions dramatically changed according to the variation of BH state parameters. It is noticed that the total observed flux is dominated by the direct emission and the lensing ring makes a small contribution while the photon ring makes a negligible contribution due to its exponential narrowness, even the photon ring intersects the thin plane more than three times to pick up a larger intensity. Assuming the spherically symmetric accretion disk, it is found that due to the Doppler effect of infalling motion, shadows of infalling accretion are found to be darker as compared to static ones. However, the size and position of the DBH shadows do not change in both cases, implying that the BH’s shadow size depends on the geometric space-time and the shadow’s luminosities rely on the accretion flow models. Finally, the discussion is done analytically and numerically, and ray-tracing methods are adopted to obtain the proper visualizations.

P-VALENTLY BAZILEVIˇ C FUNCTIONS DEFINED WITH HIGHER ORDER DERIVATIVES

The object of this paper is to derive various properties and characters for a class of p-valently Bazileviˇ c functions defined with higher order derivatives. Using the technique of Briot-Bouquet differential subordination we obtained several results, some of them presented here generalize and improve a few earlier results, and several others are new ones involving differential inequalities. These last implications deal with the symmetric open disc and symmetric conic domains with respect to the real axe. Our results extends and improves many other previous ones, and some of them are the best possible under the given assumptions.

Symmetry breaking bifurcation of membranes with boundary

We use a bifurcation theory due to Crandall and Rabinowitz to show the existence of a symmetry breaking bifurcation of a specific one parameter family of axially symmetric disc type solutions of a membrane equation with fixed boundary. In place of working directly with the fourth order membrane equation, it is replaced by a second order reduction found in Palmer and Pámpano (2022).

Numerical study of heat and mass transfer for micropolar fluid flow due to two symmetrical stretchable disks

In this study, heat transfer is analyzed for an incompressible steady laminar micropolar fluid flow among two symmetrical stretchable disks. The associated partial differential equations (PDEs) are converted into ordinary differential equations (ODEs) through appropriate similarity transformations and then solved numerically by applying the quasi-linearization method along with the finite difference method (FDM). This impact from certain inclusive parameters in the heat transfer and fluid flow is presented schematically. The results are tabulated and depict that the shear stress rises for the upper disk and the opposite trend for the lower disk. It is also noted that a couple stress and heat transfer rates were reduced across the disks. The slip factor enhances the tangential stress on the top disc and it reduces on the bottom disc. Twisting stress decreases where increases due to the effect of the slip factors.

Diagnostic Yield of Investigations in Symmetric Optic Neuropathy.

Symmetric optic neuropathy (SON) is commonly seen in neuro-ophthalmic practice and is often discovered incidentally. Although multiple investigations might be performed to discover the underlying cause, they are not always indicated. The aim of this study was to report a clinically reasonable and cost-effective approach to investigating patients with SON. SON was defined as bilateral optic neuropathy with normal and/or symmetrically decreased central visual acuity, absence of relative afferent pupillary defect, presence of symmetric optic disc pallor, symmetric thinning of peripapillary retinal nerve fiber layer on optical coherence tomography, and absence of other identifiable causes of optic neuropathy. Records of all patients diagnosed with SON seen at a tertiary university-affiliated neuro-ophthalmology practice from 2016 to 2022 were reviewed to identify the yield of various investigations. Clinical data from the initial and last follow-up visit were obtained. Subgroup analysis was performed to ascertain whether diagnostic yield is higher in patients with severe visual loss (central acuity worse than 20/40) compared with those with mild visual loss (acuity 20/40 or better). One hundred thirty-six patients met inclusion criteria. Testing for OPA1 and OPA2 mutations had the highest diagnostic yield (16.0%), followed by mitochondrial genome sequencing (13.6%), serum vitamin B12 (6.1%), and serum folate (1.6%). MRI brain was performed in 54.4% of patients and had a diagnostic yield of only 5%. Both patients who had abnormal MRI had symptoms of demyelination at presentation. Patients were followed for a mean of 15.0 (SD 21.3) months. The most frequently identified etiologies of SON were Leber hereditary optic neuropathy (8.1%), alcohol/tobacco amblyopia (7.4%), vitamin B12 deficiency (5.9%), and dominant optic atrophy (2.9%). Patients with severe visual impairment were more likely to have a final diagnosis compared with those with milder visual impairment (63.9% vs 12.0%, P < 0.001). The diagnostic yield of investigating SON in patients with preserved visual function, normal diet, and absence of other neurological symptoms is very low. It is reasonable to observe patients with SON with mild visual impairment, reserving costly investigations for those with the visual acuity worse than 20/40 or progressive course.

Strength Properties and Damage Evolution Mechanism of Single-Flawed Brazilian Discs: An Experimental Study and Particle Flow Simulation

Understanding the tensile strength properties and damage evolution mechanism in fissured rock is very important to fundamental research and engineering design. The effects of flaw dip angle on the tensile strength, macroscopic crack propagation and failure mode of symmetrical Brazilian discs of rock-like materials were investigated. A parallel bonding model was proposed to examine the damage of pre-flawed discs under splitting the load. The microscopic parameters of particles and bonds in the model that can characterize rock-like materials’ mechanical and deformation properties were obtained by calibrating against the laboratory test results. The crack development, energy evolution and damage characteristics of Brazil discs containing a single pre-existing flaw were studied at the microscopic scale. The results show that the flaw significantly weakens the strength of the Brazilian disc, and both the peak load and the initial cracking load decrease with increasing flaw angle. The failure modes of the rock-like specimens are mainly divided into three types: wing crack penetration damage mode, tensile-shear penetration damage mode and radial penetration failure mode. Except for the flaw dip angle 0°, the wing cracks generally sprouted at the tip of the pre-flaw, and the wing cracks at both tips of the pre-flaw are centrosymmetric. Crack coalescence was concentrated in the post-peak stage. Based on the particle flow code (PFC) energy partitions, the damage variables characterized by dissipation energy were proposed. The disc specimen’s pre-peak damage variables and peak damage variables decreased with increasing flaw angle, and the damage was concentrated in the post-peak phase.

Whole-transcriptome sequencing identifies key differentially expressed circRNAs/lncRNAs/miRNAs/mRNAs and linked ceRNA networks in adult degenerative scoliosis.

Adult degenerative scoliosis (ADS) is forecast to be a prevalent disabling condition in an aging society. Universally, its pathogenesis is perceived as intervertebral disc degeneration (IDD), however, a thought-provoking issue is why precisely a subset of patients with disc degeneration develop ADS. Exploring the diversities between common IDD and ADS would contribute to unraveling the etiological mechanisms of ADS. Therefore, we aimed to integrate the circRNA, lncRNA, miRNA, and mRNA expression profiles from normal adults (Normal), patients with lumbar disc herniation (LDH), and ADS by whole transcriptome sequencing, which identifies critical functional ncRNA and ceRNA networks and crosstalk between the various transcripts. The fresh whole blood samples (n = 3/group) were collected from ADS patients, LDH patients, and healthy volunteers (Normal group), which were examined for mRNA, miRNA, lncRNA, and circRNA expression and screened for differentially expressed (DE) ncRNAs. Then, Gene Ontology (GO) and KEGG analyses were performed for gene annotation and enrichment pathways on the DE RNAs, which were constructed as a lncRNA-miRNA-mRNA network. Eventually, DE RNAs were validated by qRT-PCR targeting disc nucleus pulposus (NP) tissue in ADS and LDH group (n = 10/group). Compared to the LDH group, we identified 3322 DE mRNAs, 221 DE lncRNAs, 20 DE miRNAs, and 15 DE circRNAs in the ADS. In contrast to Normal, 21 miRNAs and 19 circRNAs were differentially expressed in the ADS. The expression of multiple differentially expressed ncRNAs was confirmed by qRT-PCR analysis to be consistent with the sequencing results. In addition, GO, and KEGG analysis demonstrated that most DE mRNAs and ncRNAs target genes are involved in various biological processes, including Endocytosis, Apoptosis, Rap1 signaling pathway, Notch signaling pathway, and others. The constructed lncRNA-miRNA-mRNA co-expression network was primarily related to angiogenesis and regulation. By focusing on comparing asymmetric and symmetric disc degeneration, whole-transcriptome sequencing and bioinformatics analysis systematically screened for key ncRNAs in the development of ADS, which provided an abundance of valuable candidates for the elucidation of regulatory mechanisms. The DE ncRNAs and the lncRNA-miRNA-mRNA network are intrinsically involved in the regulation of mediator and angiogenesis, which may contribute to the insight into the pathogenesis of ADS.

The Apparent Absence of Forward Scattering in the HD 53143 Debris Disk

HD 53143 is a mature Sun-like star and host to a broad disk of dusty debris, including a cold outer ring of planetesimals near 90 au. Unlike most other inclined debris disks imaged at visible wavelengths, the cold disk around HD 53143 appears as disconnected “arcs” of material, with no forward-scattering side detected to date. We present new, deeper Hubble Space Telescope Imaging Spectrograph coronagraphic observations of the HD 53143 debris disk and show that the forward-scattering side of the disk remains undetected. By fitting our KLIP-reduced observations via forward modeling with an optically thin disk model, we show that fitting the visible wavelength images with an azimuthally symmetric disk with unconstrained orientation results in an unphysical edge-on orientation that is at odds with recent ALMA observations, while constraining the orientation to that observed by ALMA results in nearly isotropically scattering dust. We show that the HD 53143 host star exhibits significant stellar variations due to spot rotation and revisit age estimates for this system.

Disentangling the protoplanetary disk gas mass and carbon depletion through combined atomic and molecular tracers

Context. The total disk gas mass and elemental C, N, and O composition of protoplanetary disks are crucial ingredients for improving our understanding of planetary formation. Measuring the gas mass is complicated, since H2 cannot be detected in the cold bulk of the disk and the elemental abundances with respect to hydrogen are degenerate with gas mass in all disk models. Aims. We aim to determine the gas mass and elemental abundances ratios C/H and O/H in the transition disk around LkCa 15, one of the few disks for which HD data are available, in combination with as many chemical tracers as possible. Methods. We present new NOrthern Extended Millimeter Array observations of CO, 13CO, C18O, and optically thin C17O J = 2−1 lines, along with high angular-resolution Atacama Large Millimeter Array millimeter continuum and CO data to construct a representative model of LkCa 15. Using a grid of 60 azimuthally symmetric thermo-chemical DALI disk models, we translated the observed fluxes to elemental abundances and constrained the best-fitting parameter space of the disk gas mass. Results. The transitions that constrain the gas mass and carbon abundance the most are C17O J = 2−1, N2H+ J = 3−2 and HD J = 1−0. Using these three molecules, we find that the gas mass in the LkCa 15 disk is Mg = 0.01−0.004+0.01 M⊙, which is a factor of 6 lower than previous estimations. This value is consistent with cosmic ray ionization rates between 10−16−10−18 s−1, where 10−18 s−1 is a lower limit based on the HD upper limit. The carbon abundance is C/H = (3 ± 1.5) × 10−5, implying a moderate depletion of elemental carbon by a factor of 3–9. All other analyzed transitions also agree with these numbers, within a modeling uncertainty of a factor of 2. Using the resolved C2H image we find a C/O ratio of ~1, which is consistent with literature values of H2O depletion in this disk. The absence of severe carbon depletion in the LkCa 15 disk is consistent with the young age of the disk, but stands in contrast to the higher levels of depletion seen in older cold transition disks. Conclusions. Combining optically thin CO isotopologue lines with N2H+ is promising with regard to breaking the degeneracy between gas mass and CO abundance. The moderate level of depletion for this source with a cold, but young disk, suggests that long carbon transformation timescales contribute to the evolutionary trend seen in the level of carbon depletion among disk populations, rather than evolving temperature effects and presence of dust traps alone. HD observations remain important for determining the disk’s gas mass.

On a New Subclass of q-Starlike Functions Defined in q-Symmetric Calculus

Geometric function theory combines geometric tools and their applications for information and communication analysis. It is also successfully used in the field of advanced signals, image processing, machine learning, speech and sound recognition. Various new subclasses of analytic functions have been defined using quantum calculus to investigate many interesting properties of these subclasses. This article defines a new class of q-starlike functions in the open symmetric unit disc ∇ using symmetric quantum calculus. Extreme points for this class as well as coefficient estimates and closure theorems have been investigated. By fixing several coefficients finitely, all results were generalized into families of analytic functions.

Mechanical intelligent wave energy harvesting and self-powered marine environment monitoring

Harvesting wave energy to power wireless sensors can realize marine environment monitoring. However, the low frequency and irregularity of waves, as well as the harsh marine environment, have become bottlenecks limiting the development of wave energy harvesting. Herein, we propose a novel concept of mechanical intelligent energy harvesting, i.e., adaptive external excitation and regulation of energy harvesting system by mechanical structure or mechanism rather than electrical components, and illustrate this concept by designing an irregular wave energy harvesting system. The proposed gravity-driven roller and seesaw-inspired structure are sensitive to low-frequency and irregular excitation, thereby wave energy can be more easily harvested into the system. Further, the bidirectional swinging of the seesaw is converted into a high-speed unidirectional rotation of the permanent magnet disc in one direction, resulting in a significant increase in the efficiency of electromechanical conversion. Moreover, symmetrical discs on both sides can rotate synchronously via magnetic coupling mechanism, which increases the magnetic flux in the coils for higher output power and the consistent phase of the voltage is conducive to the use of electricity. Besides, the rolling behavior is used by the triboelectric nanogenerator (TENG) to convert more mechanical energy into electricity without affecting the electromagnetic energy harvester. The experimental results show that the harvester can work effectively at the ultra-low frequency (0.1 Hz) and it can charge a 0.47 F capacitor to 5 V within 6 min to achieve a self-powered wireless marine environment monitoring system under simulated wave excitation. This work demonstrates that mechanical intelligent energy harvesting is a potential solution for irregular energy harvesting and self-powered Internet of Things (IoT).

Evaluation of Spinopelvic Parameters in Patients with Different Grades of Intervertebral Disc Degeneration in Lumbosacral Spine vs Normal Asymptomatic Population: A Retrospective Observational Study

Introduction: Spinopelvic malalignment causes continual backache. Intervertebral Disc Degeneration (IDD) is a leading cause of low backache. Understanding the relationship between spinopelvic parameters and IDD can help with better diagnosis and treatment and avoid unnecessary investigations. Aim: To measure radiographic spinopelvic parameters of patients diagnosed with varying grades of IDD in the lumbosacral spine on Magnetic Resonance Imaging (MRI), and to compare them with radiographs of the asymptomatic population (controls). Materials and Methods: A hospital-based retrospective observational study was done from January 2021 to August 2022 at a tertiary care hospital in Uttar Pradesh, India with 80 patients diagnosed with IDD on MRI and 80 controls. Cases were defined as patients diagnosed to have IDD on MRI and controls were those individuals who did not have disc degeneration on MRI. Lateral lumbosacral spine radiographs were taken, and spinopelvic parameters {Pelvic Tilt (PT), Sacral Slope (SS), Pelvic Incidence (PI), Lumbar Lordosis (LL), lumbo-sacral angle, and sacral horizontal angle} were measured using Surgimap Spine Software. T-test and Chi-square test were used for comparison between cases and controls. Results: Six patients had asymmetric disc bulge, 11 had symmetric disc bulge, 18 had disc extrusion and 45 had disc protrusion. Mean PT in patients with IDD was 11.05±3.84°, and control was 8.65±3.19°, p-value=0.009. Mean SS in case group was 38.38±3.03° and control was 36.56±3.43°, p-value=0.031. The mean PI of cases was 49.44±8.39° and control 46.19±9.01°, p-value=0.02. LL angle was higher in IDD at 46.34°, and was 45.36° in healthy individuals, without statistically significant difference. The mean lumbo-sacral angle in both study groups was similar. The mean Sacral Inclination Angle (SIA) was found to be 43.99° and 44.96° in the case and control group respectively without showing significant differences. A statistically significant difference was found only for the comparison of PT between different grades of IDD (p-value=0.039). Conclusion: Using Surgimap Spine Software, one can predict the individuals that possess a greater propensity of developing degeneration of disc and chronic low back pain in a more costeffective manner.

On a Certain Subclass of p-Valent Analytic Functions Involving q-Difference Operator

This paper introduces and studies a new class of analytic p-valent functions in the open symmetric unit disc involving the Sălăgean-type q-difference operator. Furthermore, we present several interesting subordination results, coefficient inequalities, fractional q-calculus applications, and distortion theorems.

Hole spin manipulation in inhomogeneous and nonseparable electric fields

The usual models for electrical spin manipulation in semiconductor quantum dots assume that the confinement potential is separable in the three spatial dimensions and that the AC drive field is homogeneous. However, the electric field induced by the gates in quantum dot devices is not fully separable and displays significant inhomogeneities. Here, we address the electrical manipulation of hole spins in semiconductor heterostructures subject to inhomogeneous vertical electric fields and/or in-plane AC electric fields. We consider Ge quantum dots electrically confined in a Ge/GeSi quantum well as an illustration. We show that the lack of separability between the vertical and in-plane motions gives rise to an additional spin-orbit coupling mechanism (beyond the usual linear and cubic in momentum Rashba terms) that modulates the principal axes of the hole gyromagnetic g-matrix. This non-separability mechanism can be of the same order of magnitude as Rashba-type interactions, and enables spin manipulation when the magnetic field is applied in the plane of the heterostructure even if the dot is symmetric (disk-shaped). More generally, we show that Rabi oscillations in strongly patterned electric fields harness a variety of g-factor modulations. We discuss the implications for the design, modeling and understanding of hole spin qubit devices.

Certain Coefficient Problems for q-Starlike Functions Associated with q-Analogue of Sine Function

This study introduces a subclass Sqs* of starlike functions associated with the q-analogue of the sine function defined in symmetric unit disk. This article comprises the investigation of sharp coefficient bounds, and the upper bound of the third-order Hankel determinant for this class. It also includes the findings of Zalcman and generalized Zalcman conjectures for functions of this class.

Extraembryonic tissue in chelicerates: a review and outlook.

The formation of extraembryonic membranes (EEMs) contributes to the proper development of many animals. In arthropods, the formation and function of EEMs have been studied best in insects. Regarding the development of extraembryonic tissue in chelicerates (spiders and relatives), most information is available for spiders (Araneae). Especially two populations of cells have been considered to represent EEMs in spiders. The first of these potential EEMs develops shortly after egg deposition, opposite to a radially symmetrical germ disc that forms in one hemisphere of the egg and encloses the yolk. The second tissue, which has been described as being extraembryonic is the so-called dorsal field, which is required to cover the dorsal part of the developing spider germ rudiment before proper dorsal closure. In this review, we summarize the current knowledge regarding the formation of potential extraembryonic structures in the Chelicerata. We describe the early embryogenesis of spiders and other chelicerates, with a special focus on the formation of the potential extraembryonic tissues.This article is part of the theme issue ‘Extraembryonic tissues: exploring concepts, definitions and functions across the animal kingdom’.

Simulation of Thermal Surface Waves in a Protoplanetary Disk in a Two-Dimensional Approximation

Theoretical models predict that the obscuration of stellar radiation by irregularities on the surface of a protoplanetary disk can cause self-generating waves traveling towards the star. However, this process is traditionally simulated using the 1+1D approach, the key approximations of which - vertical hydrostatic equilibrium of the disk and vertical diffusion of IR radiation - can distort the picture. This article presents a two-dimensional radiative hydrodynamic model of the evolution of an axially symmetric gas and dust disk. Within this model, but using simplified assumptions from 1+1D models, we have reproduced the spontaneous generation and propagation of thermal surface waves. The key conclusion of our work is that taking into account two-dimensional hydrodynamics and diffusion of IR radiation suppresses the spontaneous generation and development of thermal waves observed in the 1+1D approximation. The search for the possibility of the existence of surface thermal waves should be continued by studying the problem for various parameters of protoplanetary disks.

Modelling of Ceramic Particle Motion during Semi-Solid Forming of Aluminium Matrix Composites via CFD-DEM Four-Way Coupling

Today, aluminium matrix composites (AMC) are widely used for the manufacturing of lightweight, yet highly stressed components in automotive, aeronautic and electrical engineering. In order to achieve particle distributions as homogeneous as possible within these component’s volumes and thus ensure optimum component properties, efforts are being made to simulate the manufacturing process prior to production. In this paper, AMC with extremely high particle fractions of more than 25 vol.% are considered in particular, as their processing still poses significant technological challenges. To model the particle motion in a computational fluid dynamics (CFD) simulation of the semi-solid forming process of this type of materials, a Lagrangian multiphase approach combining CFD and discrete element method (DEM) was used. Here, the DEM allowed all particle-particle interactions to be considered. Thus, different parameters influencing particle agglomeration, particle distribution as well as particle interaction with the cavity can be investigated during a numerical study. More specifically, the influence particle parameters such as cohesion forces and the influence of the forming speed onto the particle distribution in the final component ́s volume was analysed. The simulations were performed for a symmetric disc geometry. A forming tool was already available for this geometry, with which components could be manufactured to validate the simulation results. In the end, the study shows that by using four-way CFD-DEM coupling, simulation predictability for the semi-solid forming process of AMC could be significantly improved.