Search Results (258)

The use of computational fluid dynamics (CFD) to study hemodynamics in arteries offers significant potential for addressing complex flow problems. Due to its enhanced performance hardware and software, CFD has become an important approach for studying hemodynamics in human arteries. This approach is utilized to investigate hemodynamics and forecast risk factors for atherosclerotic lesion development and progression, including circulatory flow, and to analyze local flow fields and flow profiles resulting from geometric changes. This foundational study will aid in analyzing blood flow behavior through the abdominal aorta and the origin and courses of renal arteries, as well as investigating the causes of disorders such as atherosclerosis and hypertension. The current study investigates three idealized abdominal aorta–renal artery junction models under varying blood pressure settings. Materialise software V19 was used to extract the geometry data to create idealized 3D abdominal aorta–renal branching models. Unsteady flow simulations were performed in ANSYS Fluent, utilizing rigid walls and Newtonian and Carreau–Yasuda viscosity conditions. Oscillatory shear index (OSI) and Time-averaged wall shear stress (TAWSS) were measured to enhance understanding of atherosclerotic plaque formation and progression. Also, the effect of geometric change at the bifurcation area was explored, and it was discovered that this location causes considerable vortex forming zones. The evident velocity reduction and backflow development were seen, reducing shear stress. The findings indicate that low TAWSS < 0.4 Pa and OSI > 0.15 areas within the bifurcation region are more susceptible to atherosclerosis development. Full article

Background/Objective: Traditional hip implant evaluations often overlook patient-specific dynamic loadings. This study investigates the performance of novel collared hip implant designs under walking conditions, focusing on geometric profiles and two common stem materials: Ti-6Al-4V and CoCr alloy. Methods: Patient-specific dynamic forces were applied using commercial finite element analysis, adhering to ISO and ASTM standards. Four cross-sectional profiles—circular, elliptical, oval, and trapezoidal—were initially evaluated for induced stresses and displacements. Subsequently, wear characteristics at implant junctions were analyzed, comparing CoCr (MC 1) and Ti-6Al-4V (MC 2) stems. The study also assessed the impact of using Ultra-High Molecular Weight Polyethylene (UHMWPE) acetabular cups. Results: The elliptical (CS 2) cross-sectional profile demonstrated superior performance. Junction analysis revealed that the CoCr stem (MC 1) exhibited a stem-to-head sliding distance four times higher and contact pressure 5.5 times higher than the Ti-6Al-4V stem (MC 2). Specifically, MC 1 showed 82% higher contact pressure and 89% greater sliding distance at the stem–head junction compared to MC 2. Additionally, utilizing UHMWPE cups effectively eliminated squeaking sounds attributed to CoCr cups due to superior wear resistance. Conclusions: The combination of an elliptical (CS 2) cross-sectional profile with a Ti-6Al-4V stem and UHMWPE acetabular cup offers optimal performance. This configuration significantly reduces wear and contact pressure, suggesting enhanced functionality and durability for hip implants under dynamic loading conditions. Full article

Supercritical carbon dioxide (sCO₂) is characterized by low viscosity and a peak in specific heat capacity near the pseudo-critical point, making it a promising coolant for microelectronics. However, most existing sCO₂ test rigs are designed for large-scale thermodynamic cycle studies and lack the capability for controlled, localized heat transfer measurements in small channels. This work presents CO₂-SASS (Scientific Assessment of heat transfer in the Supercritical State), a modular, high-pressure test rig designed to measure local heat transfer coefficients and pressure drops in stainless-steel tubes with diameters on the order of 1–3 mm. The system provides independent control of pressure, mass flow and heating, with direct local wall and fluid temperature as well as precise absolute and differential pressure measurements. Particular emphasis is placed on high-accuracy temperature acquisition, including individual thermocouple calibration and cold-junction bias correction. A detailed uncertainty analysis highlights the dominant role of temperature measurement accuracy, especially for small wall–fluid temperature differences near the pseudo-critical point. Full article

With the rapid development of electrified railways in high-altitude regions, section insulators in catenary systems frequently experience gap breakdown and surface flashover under low atmospheric pressure conditions, posing serious threats to safe train operation. This paper investigates the discharge mechanisms of section insulators in high-altitude environments and conducts research on discharge characteristics under extremely non-uniform electric fields, along with structural optimization. First, the physical mechanisms of gap discharge and surface flashover in section insulators are analyzed. A three-dimensional electric field simulation model of the section insulator is established, and numerical analysis is performed to reveal the electric field distribution characteristics. The results indicate that the electric field is predominantly concentrated at the junction between metal electrodes and insulators, as well as at the tip of the arcing horn. The local maximum field strength reaches 3.84 × 10⁵ V/m, exceeding the corona inception field strength of air, which readily induces discharge. Subsequently, power frequency and lightning impulse discharge tests are conducted in both plain region and regions at an altitude of 4300 m. The results show that under high-altitude conditions, the power frequency breakdown voltage decreases by 28%, and the 50% lightning impulse breakdown voltage decreases by 42%. The discharge voltages under standard atmospheric conditions are obtained through correction. Finally, optimization schemes involving arcing horn structural modification and surface coating application are proposed. Adjusting the arcing horn angle to 55° and adding a grading ring structure with a radius of 70 mm reduces the local maximum field strength by 26%. After applying an RTV insulating coating, the field strength at the junction decreases by 35.9%, effectively enhancing the insulation performance of section insulators in high-altitude regions. Full article

The lack of integrity at the implant–abutment junction (IAJ) contributes to problems such as micromovements and microbial colonisation. This study aimed to (1) design a protocol for assessing microleakage at the IAJ using chromophore analysis not previously reported for this specific application, (2) compare gas and dye leakage between titanium (Ti) and cobalt chrome (CoCr) abutments, and (3) assess the effect of gold (Au) gilding on sealing. Forty abutments were divided into five groups: milled Ti (MTi); cast CoCr (CCoCr); milled CoCr (MCoCr); cast CoCr with Au gilding (CCoCrG); and milled CoCr with Au gilding (MCoCrG). Samples were subjected to internal pressure within a gas and dye reservoir. Chromophore analysis via UV-Vis spectrometer was used to calculate crystal violet leakage concentrations. Scanning electron microscopy (SEM) revealed close adaptation in the MTi and MCoCr groups, contrasting with irregularities in the CCoCr groups. Correspondingly, gas leakage and dye leakage were most prevalent in the CCoCr group. Fisher exact test demonstrated a statistically significant difference (p = 0.026) between the MCoCr and CCoCr abutments. While CCoCr exhibited the highest failure rate (62.5%), Au gilding demonstrated a trend toward reduced leakage (25% failure rate), though this did not reach statistical significance (p = 0.315). This chromophore analysis represents a viable and objective assessment of IAJ integrity. Full article

This study presents an ASME-based structural assessment of the head–shell junction in a 60 m³ pressurized railway tank wagon subjected to an internal pressure of 0.45 MPa, combining classical shell theory with finite element analysis (FEA) in accordance with ASME Section VIII Division 2 stress categorization and linearization procedures. An analytical model based on the moment theory of shells of revolution was developed to describe displacement and rotation compatibility at the ellipsoidal head–cylindrical shell junction, allowing for the determination of contour interaction loads governing membrane–bending coupling in the discontinuity region. The calculated contour loads (Q₀ = 795 N/mm, M₀ = 13,350 N·mm/mm) indicate localized membrane–bending interactions caused by geometric discontinuity. Finite element simulations using axisymmetric (2D) and full 3D models were evaluated through the ASME VIII-2 stress linearization procedure, enabling comparison between analytical predictions and numerical results. The maximum equivalent stress according to the Coulomb–Tresca criterion reached 115 MPa (2D) and 117 MPa (3D), with less than 2% deviation, confirming the adequacy of the axisymmetric model. Stress linearization shows that the maximum combined primary membrane and bending stress (109.5 MPa) remains well below the ASME allowable limit of 308 MPa, while the discontinuity influence zone extends approximately 120–150 mm from the junction. The results confirm compliance with ASME VIII Division 2 requirements and demonstrate that the combined analytical–numerical approach provides a reliable method for evaluating stress concentration effects in railway tank wagons. Full article

Aortic valve disease is increasingly recognized as a chronic, progressive condition in which the initial valve intervention exerts a decisive influence on all subsequent therapeutic options. The persistence of prosthesis–patient mismatch (PPM), often driven by implantation of small surgical prostheses (≤21–23 mm), is associated with higher residual transvalvular gradients, attenuated left ventricular reverse remodeling, inferior long-term survival, and compromised outcomes following valve-in-valve (ViV) transcatheter procedures. Accumulating clinical and imaging evidence indicates that aortic annular enlargement (AAE), particularly using contemporary Y-incision and extended “roof” reconstruction techniques, can safely and reproducibly expand the annulus, sinuses of Valsalva, and sinotubular junction, thereby permitting implantation of larger prostheses and substantially reducing the risk of PPM. Insights from computational fluid dynamics further demonstrate that annular and root enlargement favorably alters postoperative flow dynamics, resulting in lower peak velocities, reduced pressure gradients, and more physiologic flow patterns in both primary surgical valve replacement and simulated ViV settings. From a lifetime management perspective, valve diameter optimization emerges as a critical determinant of both immediate hemodynamic performance and future procedural feasibility. Surgical programs that adopt a systematic approach to anatomic assessment, valve sizing strategy, PPM surveillance, and ViV preparedness may achieve meaningful improvements in short- and long-term outcomes. This review integrates anatomic, operative, hemodynamic, and quality-oriented evidence to support consideration of valve upsizing as a central principle in contemporary aortic valve replacement. Full article

Gastroesophageal reflux disease (GERD) is a common chronic condition mainly caused by the dysfunction of the antireflux mechanism at the gastroesophageal junction. This is composed of the lower esophageal sphincter and the crural diaphragm. Increasing evidence suggests that diaphragmatic dysfunction and reduced inspiratory muscle strength may contribute to the persistence of GERD symptoms. Although respiratory physiotherapy has shown beneficial effects, the role of a structured inspiratory muscle training (IMT) program has not been sufficiently examined. This study aims to investigate the effects of an inspiratory muscle training program on inspiratory muscle strength and secondary clinical outcomes in individuals with GERD. A total of thirty adults with a confirmed GERD diagnosis will be enrolled in a two-arm randomized controlled trial. These volunteers will be randomly assigned either to the experimental group, which will undergo a 3-month inspiratory muscle training (IMT) using tapered flow resistive loading at 40% of maximal inspiratory pressure (MIP), or to the control group, which will receive sham IMT with a consistent low resistance. Primary outcomes will include maximal inspiratory pressure (MIP) and maximal dynamic inspiratory pressure (S-index). Secondary outcomes will assess GERD symptoms, disease-related quality of life, and pulmonary function. Measurements will be performed at baseline, at three months of intervention, and at six months from recruitment (follow-up). IMT is expected to lead to significant improvements in inspiratory muscle strength, symptom burden, and quality of life compared with sham training. This trial will provide novel evidence regarding the role of inspiratory muscle training as a non-pharmacological intervention in the management of GERD. Trial registration: ClinicalTrials.gov Identifier: NCT07131397. Full article

Background: Traditional echocardiographic assessment of aortic stenosis (AS) using aortic valve area (AVA) may overestimate severity due to pressure recovery phenomena, while subclinical myocardial dysfunction remains undetected despite preserved ejection fraction. This study evaluated whether energy loss index (ELI)—which accounts for pressure recovery—demonstrates superior correlation with global longitudinal strain (GLS), a marker of subclinical myocardial dysfunction, compared to conventional AVA-based classification in patients with moderate-to-severe AS and preserved left ventricular ejection fraction (LVEF). Methods: This retrospective single-center study analyzed 149 patients with moderate-to-severe AS (AVA < 1.5 cm²) and LVEF > 50% from 2015 to 2019. Among 97 patients with severe AS by AVA (<1.0 cm²), ELI was calculated using the formula ELI = (AVA × Aa)/(Aa − AVA) ÷ BSA, where Aa represents sinotubular junction cross-sectional area. Patients with ELI ≥ 0.6 cm²/m² were reclassified as moderate AS. Spearman correlation assessed relationships between AVA, ELI, and GLS. Multivariable linear regression models determined independent predictors of myocardial dysfunction, adjusting for age, body surface area, hypertension, LVEF, and mean pressure gradient. Results: ELI reclassified 28 of 97 patients (29%) from severe to moderate AS. Reclassified patients had significantly better myocardial function, with less impaired GLS (−15.0 ± 3.9% vs. −12.1 ± 5.0%, p = 0.013) and higher LVEF (60.1 ± 6.2% vs. 56.5 ± 9.1%, p = 0.017) compared to non-reclassified patients. In the overall cohort, ELI demonstrated stronger correlation with GLS than AVA (r = −0.307, p = 0.0003 vs. r = −0.209, p = 0.0115). Critically, among patients with severe AS by AVA criteria, ELI maintained significant correlation with GLS (r = −0.443, p = 0.0003) while AVA showed no correlation (r = −0.144, p = 0.159). In multivariable analysis, ELI independently predicted GLS (β = 5.847, 95% CI: 2.85–8.84, p = 0.0002; adjusted R² = 0.289), whereas AVA did not (β = 2.234, 95% CI: −1.08 to 5.55, p = 0.188; adjusted R² = 0.234). When both parameters were included simultaneously, only ELI remained significant (p = 0.0024). Conclusions: In this retrospective cohort, ELI-based reclassification identified a subgroup of patients with less severe myocardial dysfunction as measured by GLS and LVEF, and ELI demonstrated superior correlation with subclinical myocardial dysfunction compared to AVA. These findings suggest ELI may provide a more physiologically reflective assessment of hemodynamic burden in AS with preserved LVEF. However, the absence of systematic symptom assessment and clinical outcome data represents critical limitations. Prospective studies with standardized symptom evaluation, longitudinal follow-up, and adjudicated clinical endpoints are required to determine whether ELI-based reclassification improves risk stratification and clinical decision-making before this approach can be recommended for routine practice. Full article

Coral reefs in Djibouti, located at the biogeographic junction of the Red Sea and the Indian Ocean, remain among the least studied in the region despite increasing climate-driven pressures. This study provides the first scientific documentation of a large-scale bleaching event in Djibouti following the extreme thermal anomaly of 2023. Benthic surveys conducted across 16 sites in Moucha–Maskali Islands, Arta, Tadjourah, and Obock revealed bleaching at all sites, with the highest levels recorded at Ras Bir (23.4%) and Sable Blanc (24.1%), predominantly affecting thermally susceptible such as Acropora and Pocillopora. More thermally tolerant massive corals, particularly Porites, Favia, and Platygyra, exhibited limited bleaching and dominated healthier sites such as Arta. Satellite-derived sea surface temperature (SST) and Degree Heating Week (DHW) data confirmed record-breaking heat stress in 2023, with SST peaking at 35.2 °C and DHW reaching 13.87 °C·week⁻¹—the highest recorded. The pronounced spatial variability in bleaching reflects the combined influence of thermal stress, sedimentation, water quality, and reef geomorphology. Although mortality remained moderate, the findings indicate rising vulnerability of Djibouti’s reefs and underscore the urgent need for continuous monitoring, targeted management interventions, and mitigation of local stressors to enhance resilience in the region. Full article

To investigate the hypersonic boundary layer transition over complex three-dimensional configurations, this study conducted an experiment using infrared thermography, Rayleigh scattering visualization, and high-frequency pressure sensors in a Mach 6 Ludwieg wind tunnel. The infrared results indicate that increasing the Reynolds number promotes boundary layer transition on the model surface. Spectral analysis reveals a high-frequency peak centered at 250 kHz on the finless side of the windward surface. Comprehensive analysis indicates this represents high-frequency secondary instability triggered by the traveling crossflow mode in its nonlinear phase. On the finless side of the leeward surface, a typical Mack second-mode high-frequency instability amplification process is observed within the 140–280 kHz frequency band. Additionally, the spectrum results for the fin–cone junction became more complex. On the windward side, the primary energy concentration in the junction zone is observed between 80 and 200 kHz, with calculated wave packet velocities higher than those on the finless side. Wavelet analysis reveals that low-frequency modes are amplified first and gradually excite high-frequency components, with significant modal coupling appearing in the high-frequency region of the bicoherence. The leeward fin–cone junction exhibits dual-band characteristics at 60–120 kHz and 180–260 kHz, demonstrating stronger intermodal interactions. Both the windward and leeward surfaces of the fin show low-frequency transverse flow-like modes around 70–180 kHz. The spectral results for the windward and leeward sides are largely consistent, with only slight differences in amplitude levels and saturation positions. Full article

Pseudolysimachion pyrethrinum var. gasanensis (Gasan spike speedwell) is a valuable Korean endemic variety with significant horticultural potential. Despite its morphological distinctiveness, its taxonomic status and evolutionary position have remained a subject of debate. In this study, we assembled and characterized the first complete chloroplast (cp) genome of P. pyrethrinum var. gasanensis using high-throughput sequencing. The complete plastome is 152,251 bp in length, exhibiting a typical quadripartite structure with a large single-copy (LSC) region (83,191 bp), a small single-copy (SSC) region (17,690 bp), and two inverted repeats (IRs) (25,685 bp each). The genome contains 133 genes, including 88 protein-coding, 37 tRNA, and 8 rRNA genes. Genomic analysis identified 42 simple sequence repeat (SSR) units across 38 distinct loci, predominantly mononucleotide A/T motifs, which serve as potential molecular markers for variety-level identification. Selective pressure analysis revealed that the majority of protein-coding genes are under strong purifying selection (Ka/Ks < 1.0), emphasizing the evolutionary stability of the plastome. Comparative analysis of IR boundaries using IRscope revealed a high degree of structural conservation among Pseudolysimachion species, with minor variations at the junction sites. Phylogenetic analysis based on 18 complete plastomes strongly supported the monophyly of the genus Pseudolysimachion (Bootstrap = 100%) and placed P. pyrethrinum var. gasanensis as a sister to the European P. spicatum. These genomic resources provide a foundational tool for the molecular breeding, systematic conservation, and sustainable utilization of this endemic variety, while offering clarity to its taxonomic classification within the tribe Veroniceae. Full article

Background/Objectives: Cerebral angiography is a cornerstone diagnostic and therapeutic procedure for cerebrovascular diseases; however, its potential effects on vascular integrity and cellular homeostasis remain incompletely elucidated. This systematic review aims to comprehensively evaluate endothelial and histopathological alterations induced by cerebral angiographic procedures, with particular emphasis on oxidative stress, inflammation, endothelial dysfunction, and blood–brain barrier disruption. Methods: This systematic review was conducted in accordance with the PRISMA 2020 guidelines. PubMed, Scopus, and Web of Science databases were systematically searched for studies published between 1981 and 2025 using predefined keywords related to cerebral angiography, endothelial injury, oxidative stress, inflammation, and histopathological changes. A total of 1142 records were identified, and 216 duplicates were removed. Following title and abstract screening, 312 full-text articles were assessed for eligibility, of which 112 were excluded due to irrelevance or insufficient endothelial or histopathological data. Ultimately, 200 studies were included in the qualitative synthesis. The literature identification, screening, and selection process are summarized in the manuscript. The review protocol was not prospectively registered. Results: The included studies demonstrated that cerebral angiographic procedures induce endothelial and microvascular alterations through both mechanical and contrast-mediated mechanisms. Iodinated contrast agents were consistently associated with increased reactive oxygen species production, reduced endothelial nitric oxide bioavailability, mitochondrial dysfunction, and activation of pro-inflammatory signaling pathways, including nuclear factor kappa B (NF-κB). Histopathological findings revealed endothelial swelling, vacuolization, apoptosis, microthrombus formation, inflammatory cell infiltration, and disruption of endothelial junctions, leading to increased vascular permeability and blood–brain barrier impairment. Mechanical factors related to catheter manipulation and high-pressure contrast injection further exacerbated endothelial injury by altering shear stress and promoting leukocyte adhesion. The severity of endothelial damage and inflammatory responses was consistently greater in patients with comorbid conditions such as diabetes mellitus, hypertension, and atherosclerotic disease. Conclusions: Cerebral angiography may induce endothelial dysfunction and histopathological vascular injury predominantly through oxidative and inflammatory mechanisms. Optimization of contrast agent selection, refinement of procedural techniques, and implementation of endothelial-protective strategies may mitigate vascular injury and improve procedural safety. Further translational and clinical studies are warranted to identify biomarkers and protective interventions targeting angiography-induced endothelial damage. Full article

Severe crusting dermatosis affecting the mucocutaneous junctions, pressure points, and trunk of dogs fed low-quality dry food was first reported in the United States in the 1980s. Since then, only a few cases have been documented. Twenty-two adult dogs owned by private individuals were evaluated. All dogs exhibited thick crusts forming plaques and marked scaling on the face—particularly around the lips, nasal bridge, and eyelids—as well as on the paw pads, dorsal digits, abdomen, and dorsum. Pruritus ranged from moderate to severe, and all dogs showed varying degrees of lethargy and reduced activity. Each dog was fed a low-quality commercial diet. A presumptive diagnosis of dermatosis associated with poor-quality food was made. Skin biopsies from nine dogs revealed similar histopathologic changes, characterized by epidermal hyperplasia, severe parakeratotic hyperkeratosis with spongiosis, and exocytosis of lymphocytes and neutrophils. The skin lesions resolved within 15–30 days after switching to a high-quality diet. This case series highlights that dermatosis associated with low-quality food should remain in the differential diagnosis for dogs presenting with symmetric crusted and scaly lesions on the face, mucocutaneous junctions, and paws, particularly when nutritional deficiencies are suspected. Full article

Background/Objectives: Aneurysmal subarachnoid hemorrhage (aSAH) involves a sudden onset of a perfusion-pressure injury from the initial insult combined with a secondary injury phase produced by delayed cerebral ischemia, cerebrospinal fluid circulation disturbances, and generalized instability of the patient’s physiological state. The situation may be further complicated when there has been rupture of the aneurysm at the site of the carotid–posterior communicating (PCom) artery junction that occurs in conjunction with a fetal configuration of the posterior cerebral artery (fPCA), thereby making definitive treatment dependent on preserving the critical nature of the branches of the posterior circulation since the aneurysm’s neck plane coincides with the dominant posterior circulation conduit. Case Presentation: A 65-year-old female patient who was obese (Grade III BMI = 42), had chronic bronchial asthma, and arterial hypertension experienced a “thunderclap” type of headache in the right retro-orbital area followed by a syncopal episode and developed acute confusion with agitation. Upon admission to the hospital, her Glasgow Coma Scale (GCS) was 13, her FOUR score was 15, her Montreal Cognitive Assessment (MoCA) score was 12/30, her Hunt–Hess grade was 3, WFNS grade 2, and Fisher grade 4 SAH with intraventricular extension. Digital subtraction angiography (DSA) and three-dimensional rotational angiography revealed a posteriorly directed right carotid communicating aneurysm that had a relatively compact neck (approximately 2.5 mm) and sac size of approximately 7.7 × 6.6 mm, with the fPCA originating at the neck plane. Microsurgical treatment was performed with junction-preserving reconstruction with skull base refinement, temporary occlusion of the internal carotid artery for a few minutes, placement of clips reconstructing the carotid–PCom interface, and micro-Doppler verification of patent vessel. Postoperatively, the blood pressure was kept within the range of 110–130 mmHg with nimodipine and closely monitored. The neurological recovery was sequential (GCS of 15 by POD 2; MoCA of 22 by POD 5). By POD 5 CT scan, the clip remained positioned in a stable fashion without evidence of infarct, hemorrhage, or hydrocephalus; at three months she was neurologically intact (mRS 0; Barthel 100; MoCA 28/30), and CTA confirmed persistent exclusion of the aneurysm and preservation of fPCA flow. Conclusions: In cases where the ruptured aneurysm is located at the carotid communicating junction with the PCom artery in a configuration of the posterior cerebral artery that is described as fetal, clip treatment should be viewed as a form of branch-preserving junction reconstruction of the carotid–PCom junction supported by adherence to controlled postoperative physiology and close ppostoperativesurveillance. Full article