Search Results (365)

Background/Objectives: The rapid progression of stroke often results in irreversible brain damage and poor outcomes when treatment is delayed. Prophylactic administration of FAD012 (3,5-dimethyl-4-hydroxycinnamic acid), a synthetic derivative of ferulic acid (FA), has demonstrated cerebroprotective effects in ischemic models through antioxidant and endothelial protective mechanisms. This study investigated the effects of FAD012 on cerebral infarction and blood–brain barrier (BBB) integrity using a photothrombotic stroke model in rats. Methods: Male Sprague Dawley rats received a single intraperitoneal injection of FAD012 or FA (100 or 300 mg/kg) 60 min prior to stroke induction. Under isoflurane anesthesia, the middle cerebral artery was exposed, and stroke was induced by intravenous administration of Rose Bengal followed by green laser irradiation. Cerebral blood flow (CBF) was monitored by laser Doppler flowmetry. BBB disruption was evaluated by Evans Blue extravasation and immunohistochemistry for tight junction (TJ) proteins. Results: Control rats exhibited extensive infarction, BBB disruption, and reduced expression of claudin-5, occludin, and ZO-1, along with fragmented collagen IV. In contrast, FAD012 (300 mg/kg) significantly attenuated CBF reduction, reduced infarct size, preserved BBB integrity, and maintained TJ protein expression, with greater efficacy than an equivalent dose of FA. FAD012 also preserved the expression and phosphorylation of endothelial nitric oxide synthase (eNOS), a key marker of vascular integrity. The CBF-preserving effect of FAD012 was completely abolished by N^G-nitro-L-arginine methyl ester (L-NAME), a nitric oxide synthase inhibitor. Conclusions: These findings suggest that FAD012 protects endothelial function, thereby contributing to the maintenance of CBF and BBB integrity, supporting its potential as a prophylactic therapeutic agent for ischemic stroke. Full article

Background: Glaucoma is a multifactorial optic neuropathy and the leading cause of irreversible blindness worldwide. Vascular mechanisms, including impaired perfusion of the optic nerve head, are increasingly recognized as contributors to disease progression. Optical coherence tomography angiography (OCTA) enables non-invasive assessment of retinal and choroidal microvasculature, including peripapillary microvasculature dropout (MvD), which may serve as a marker of glaucomatous damage. Methods: A cross-sectional case–control study was conducted, including patients with primary open-angle glaucoma (OAG) and healthy controls. All participants underwent a comprehensive ophthalmic evaluation and OCTA imaging using the PLEX Elite 9000 system. Peripapillary vessel density (pVD), flow index (pFI), peripapillary choroidal thickness (PCT), β-zone parapapillary atrophy (β-PPA), and choroidal vascular indices were measured. MvD was defined as the complete absence of microvasculature within the β-PPA boundary. Statistical analyses included univariate and multivariate regression models to examine variables associated with PCT and to assess the association between MvD and visual field mean defect (MD), as well as other glaucoma characteristics. ROC curve analysis was performed to evaluate the ability of MvD to discriminate between different levels of visual field defects. Results: A total of 87 eyes (41 glaucomatous, 46 controls) were analyzed. Glaucoma patients exhibited significantly lower pVD, pFI, PCT, and choroidal vascular indices compared to the controls. MvD was detected in 10 glaucomatous eyes and was associated with a larger β-PPA area, smaller choroidal luminal and stromal areas, and worse mean deviation (MD) values. Multivariate regression showed that the number of ocular hypotensive treatments and StructureIndex variables were significantly associated with PCT (adjusted R² = 0.14). Logistic regression analysis identified MD, MD slope, and β-PPA area as variables significantly associated with the presence of MvD. ROC analysis showed that the presence of MvD had good discriminatory ability for visual field mean defects (MDs) (AUC = 0.77, 95% CI: 0.69–0.87; p = 0.005). Conclusions: Peripapillary MvD detected by OCTA is associated with reduced choroidal vascularity, increased β-PPA, and greater visual field deterioration in glaucoma patients. MvD may serve as a structural marker associated with functional deterioration in glaucoma patients. Full article

Formation damage sensitivity is a primary constraint on productivity in coalbed methane (CBM) reservoirs. Conventional experimental methods, which often employ crushed or plug coal samples, disrupt the natural fracture network, thereby overestimating matrix damage and underestimating fracture-related damage. In this study, synchronous comparative experiments were conducted using raw coal and briquette coal cores, integrated with scanning electron microscopy (SEM) and nuclear magnetic resonance (NMR) analyses to characterize coal composition and pore structure. This approach elucidates the underlying mechanisms controlling reservoir sensitivity. The main findings are as follows: The dual-sample comparative system reveals substantial deviations in traditional experimental assessments. Due to post-dissolution compaction, briquette coal samples overestimate acid sensitivity while underestimating water sensitivity. Stress sensitivity is primarily attributed to the irreversible compression of natural fractures. Differences in acid sensitivity are governed by structural integrity: mineral dissolution leads to collapse in briquette coal, whereas fractures help maintain stability in raw coal. Raw coal exhibits a lower critical flow rate for velocity sensitivity and undergoes significant water sensitivity damage below 1 MPa. Both sample types show weak alkaline sensitivity, with damage acceleration observed within the pH range of 7 to 10. Full article

Introduction: Leukoaraiosis (LA) or white matter disease is a significant component of vascular dementia. There is a large overlap noted between normal-pressure hydrocephalus (NPH) and LA. A previously reported lumped parameter modelling study of NPH led to novel findings in this disease. Given the overlap between LA and NPH, the purpose of the current study is to perform a lumped parameter study into LA to see if the vascular pathophysiology is similar to NPH. Methods: A lumped parameter model originally developed to study normal-pressure hydrocephalus was extended to investigate LA. The model was constrained by the known cerebral blood flow and cerebral blood volumes found in LA, as derived from the literature. Results: Similar to NPH, in LA, the model predicted a balanced increase in arterial and venous outflow resistance, with the resulting ischemia affecting the white matter rather than the grey matter. However, unlike NPH, in LA, the findings are irreversible, most likely due to structural venous wall changes. Conclusions: The model suggests that the vascular physiology of LA maybe similar to NPH. A common pathophysiology is discussed based on a pulsation-induced increase in the venous outflow resistance. Full article

Sand is the backbone of modern civilization and faces heightened demand in the Anthropocene. The uncontrolled extraction of sand raises concerns regarding its irreversible ecological impact. The sand industry is not well understood, especially from the perspective of sustainability. To address this knowledge gap, this systematic review combines policy analysis with the use of material flow analysis (MFA) indicators, environmental externalities, and geopolitics to assess the overall sustainability of the sand industry. By utilizing trade data, this study identified the primary importers and exporters of sand within each continent and selected the top 3–4 countries for analysis. Based on these countries, relevant studies in the literature on the trade and domestic extraction of sand and that used the principles of MFA were found to assess the patterns of its consumption. Illicit sand mining adds a further challenge regarding data accuracy and verification. This study revealed that China’s consumption of sand surpasses that of all the other countries studied, at 17,700 million tonnes, and China has the highest mass of recycled aggregates in use. Using gross domestic product as a proxy for size of the economy, it was found that China consumed 0.001251 million tonnes of sand per million USD. European nations showed a striking balance in their sand industries by placing equal importance on using virgin sand and recycled aggregates, thus contributing to a circular economy. The use of MFA for future research can reveal hidden flows by positioning itself as a science–policy interface, enabling greater circularity within the lock-ins of the construction sector. Full article

The prevalence of (TDF)-induced Acute Kidney Injury (AKI) in Africa is a concern, given the widespread use of Tenofovir disoproxil fumarate (TDF) for Human Immunodeficiency Virus (HIV) therapy. Current tests used to detect AKI are based on increased urinary creatinine levels and are often not sensitive and specific enough for early detection. There is a need for more sensitive and specific rapid tests for the early detection of AKI, particularly in resource-limited countries for early detection and timely intervention. In the present study, a multiplex lateral flow assay, named An Africa Lateral Flow Assay-Based Early Recognition Test for Acute Kidney Injury (ALERT-AKI), detecting a set of three unique biomarkers of TDF-induced AKI was developed with a limit of detection of 2 ug/mL to 50 ug/mL, indicating the suitability of developed test for determining the selected AKI biomarkers in a clinically relevant range. This study shows proof of concept for a multiplex lateral assay tested on clinical samples. The ALERT-AKI multiplex platform will be the first of its kind once further clinical studies are conducted, offering multiple advantages, including early detection, simplicity, rapidity, high sensitivity, cost-effectiveness, and timely intervention, potentially reducing the severity and prevalence of AKI. Using a multiplexed protein biomarker rather than single protein molecules will allow for a much more accurate detection of kidney damage before it becomes significant or irreversible. Full article

Background/Objectives: Acute scrotal pain in children and adolescents requires prompt evaluation to differentiate testicular torsion from other scrotal pathologies. Testicular torsion, a surgical emergency, can lead to irreversible testicular damage if not managed rapidly. This study aims to assess the clinical signs, diagnostic tools, and outcomes related to testicular torsion in patients presenting with acute scrotal pain. Methods: A retrospective analysis was conducted on 111 patients diagnosed with acute scrotal conditions. Clinical signs, presentation times, ultrasound findings, and treatment outcomes (surgical intervention, orchiectomy, or medical management) were evaluated. The statistical analysis was performed with a p-value < 0.05 being considered significant. Correlations between clinical signs, diagnostic imaging, and treatment modalities were assessed. Results: The most prevalent clinical signs were scrotal swelling (92.2%), pain on palpation (93.5%), and scrotal hyperemia (84.4%). Testicular torsion was strongly associated with the absence of the cremasteric reflex (p < 0.0001) and testicular retraction (p < 0.0001). Ultrasound findings, including absent blood flow and testicular heterogeneity, were highly predictive of surgical intervention (p < 0.01). Patients presenting within 8 h of symptom onset had higher success rates of detorsion and testicular preservation. Conclusions: Timely and accurate clinical assessment, including the identification of key signs such as the absence of the cremasteric reflex and testicular retraction, is critical for differentiating testicular torsion from other conditions. Ultrasound findings are pivotal in guiding treatment decisions in cases of clinical uncertainty. Early intervention significantly improves testicular viability and outcomes, underscoring the importance of rapid diagnosis and management. Full article

This study presents a novel mathematical model for bubble cavitation, demonstrating its application in the numerical simulation of steam bubble dynamics within hydrodynamic cavitation phenomena. While previous research has largely focused on the negative consequences of cavitation or its industrial applications, a key unresolved issue remains the physical mechanism of bubble destruction during collapse. This paper investigates the conditions leading to the instability of a spherical bubble’s surface, which in turn causes its irreversible collapse. The model is based on the hypothesis that a bubble is destroyed when its surface temperature exceeds a critical value (T_cr). The modified model, which accounts for heat and mass transfer processes at the bubble boundary, was used to analyse the behaviour of bubbles under different flow conditions. Our computational experiments show that the bubble collapses when the surface temperature surpasses the critical point, irrespective of its size. A comparison of theoretical and experimental data on bubble behaviour during hydrodynamic cavitation validates the proposed criterion. Specifically, the collapse of bubbles in the Venturi tube upon exceeding a critical temperature is shown, supported by experimental data with a maximum error of 6%.The results suggest that the hydraulic parameters of the flow are key factors determining the intensity of cavitation, and that the fulfillment of the condition T_s ≥ T_cr (T_cr = 647 K, p_cr = 22.5 MPa) can serve as a reliable criterion for bubble destruction. Full article

Stirling engines are widely applied due to their high thermal efficiency and ability to operate with diverse heat sources. An accurate thermodynamic model is essential for optimising engine design parameters and evaluating the thermal performance of Stirling engines. Despite the fact that the Schmidt model and the ideal adiabatic model quite commonly approximate the performance, they frequently neglect critical loss mechanisms such as regenerator inefficiency, flow resistance, and mechanical friction. In order to address the limitations identified, this study proposes a numerical performance analysis of the GENOA 03 α-type Stirling engine under real operating conditions. The analysis is conducted using an extended second-order Simple Model and Finite Speed approach. The model incorporates significant irreversibilities, including the effectiveness of the regenerator, pressure losses, the shuttle effect, and mechanical friction. A novel aspect of this study is the experimental determination of mechanical friction losses under no-load conditions at various rotational speeds, which are then integrated into the numerical model. The findings of the study indicate that regenerator imperfection and friction losses are significant factors affecting the performance of Stirling engines, and contribute approximately 23% and 14% of the total engine inefficiency, respectively. The model also identifies 1.25 MPa as the minimum operational pressure threshold. The proposed approach integrates experimental data with modified analytical modelling providing more accurate performance predictions for Stirling engines. Full article

Efficient reinjection is critical for maintaining reservoir pressure and ensuring the sustainable development of sandstone geothermal systems. However, complex thermal–hydraulic–chemical (THC) interactions often lead to progressive permeability reduction, significantly impairing injection performance. This study systematically investigates the coupled effects of injection flow rate, temperature, and suspended particle size on permeability evolution during geothermal reinjection. Laboratory-scale core flow-through experiments were conducted using sandstone samples from the Guantao Formation in the Huanghua Depression, Bohai Bay Basin. The experimental schemes included graded flow rate tests, temperature-stepped injections, particle size control, long-term seepage, and reverse-flow backflushing operations. The results reveal that permeability is highly sensitive to injection parameters. Flow rates exceeding 6 mL/min induce irreversible clogging and pore structure damage, while lower rates yield more stable injection behavior. Injection at approximately 35 °C resulted in a permeability increase of 15.7%, attributed to reduced fluid viscosity and moderate clay swelling and secondary precipitation. Particles larger than 3 μm were prone to bridging and persistent clogging, whereas smaller particles exhibited more reversible behavior. During long-term seepage, reverse injection implemented upon permeability decline restored up to 98% of the initial permeability, confirming its effectiveness in alleviating pore throat blockage. Based on these findings, a combined reinjection strategy is recommended, featuring low flow rate (≤5 mL/min), moderate injection temperature (~35 °C), and fine filtration (≤3 μm). In addition, periodic backflushing should be considered when permeability loss exceeds 30% or a sustained injection pressure rise is observed. This study provides robust experimental evidence and practical guidance for optimizing geothermal reinjection operations. Full article

This paper presents the design of a permanent-magnet-assisted synchronous reluctance motor (PMa-SynRM) for compressor applications using Sm-series injection-molded magnets that eliminate heavy rare-earth elements. The high shape flexibility of the injection-molded magnets enables the formation of a curved multi-layer flux-barrier rotor geometry based on the Joukowski airfoil potential, optimizing magnetic flux flow under typical compressor operating conditions. Furthermore, electromagnetic performance, irreversible demagnetization behavior, and rotor stress sensitivity were analyzed with respect to key design variables to derive a model that satisfies the target performance requirements. The validity of the proposed design was confirmed through finite element method (FEM) comparisons with a conventional IPMSM using sintered NdFeB magnets, demonstrating the feasibility of HRE-free PMa-SynRM for high-performance compressor drives. Full article

The Aral Sea Basin (ASB), situated in Central Asia, serves as a prime example of a man-made environmental disaster. The practice of irrigation can be traced back to ancient times. However, the substantial water withdrawals that have occurred since the second half of the 20th century appear to have led to the irreversible drying up of the Aral Sea and the disruption of the flow of the Amu Darya and Syr Darya rivers. This study conducts a comprehensive review of satellite data from the past sixty years, drawing upon a selection of peer-reviewed papers available on Scopus. The selection of papers is conducted in accordance with a methodology that is predicated on the combination of keywords. The study focuses on geoscientific aspects, including the atmosphere, water resources, geology, and geological hazards. The primary sensors employed in this study were Terra-MODIS, NOAA-AVHRR, and the Landsat series. It is evident that certain data types, including radar data, US or Soviet archives, and very-high-resolution data such as OrbView-3, have seen minimal utilisation. Despite the restricted application of remote sensing data in publications addressing the ASB, remote sensing data offer a substantial repository for monitoring the desiccation of the Aral Sea, once the fourth largest continental body of water, and for the estimation of its water surface and volume. Nevertheless, the utilisation of remote sensing in publications concerning the Aral region remains limited, with less than 10% of publications employing this method. Sentinel-2 data has been utilised to illustrate the construction of the Qosh Tepa Canal in Afghanistan, a project which has been the subject of significant controversy, with a particular focus on the issue of water leakage. This predicament is indicative of the broader challenges confronting the region with regard to water management in the context of climate change. A comparison of the Aral Sea’s case history is drawn with analogous examples worldwide, including Lake Urmia, the Great Salt Lake, and, arguably more problematically, the Caspian Sea. Full article

This paper presents a theoretical optimization of an endoreversible compressor under steady-state conditions. A parametric study using finite-time thermodynamic principles highlights the effect of external irreversibilities on compressor performance. A compressor efficiency metric is established based on heat pump theory’s analogous performance coefficient concept. The external irreversibilities are characterized as functions of the conductance coefficients between the compressor and the low- and high-pressure reservoirs. In particular, the influence of suction and discharge tube diameters and gas pressures is investigated to determine the optimum compressor operating performance for a given gas mass flow rate. The results highlight the importance of selecting optimal suction and discharge tube diameters to improve compressor power efficiency and minimize energy consumption during gas compression. Full article

A model for the flow and thermal explosion of a micropolar gas is investigated, assuming the equation of state for a real gas. This model describes the dynamics of a gas mixture (fuel and oxidant) undergoing a one-step irreversible chemical reaction. The real gas model is particularly suitable in this context because it more accurately reflects reality under extreme conditions, such as high temperatures and high pressures. Micropolarity introduces local rotational dynamic effects of particles dispersed within the gas mixture. In this paper, we first derive the initial-boundary value system of partial differential equations (PDEs) under the assumption of spherical symmetry and homogeneous boundary conditions. We explain the underlying physical relationships and then construct a corresponding approximate system of ordinary differential equations (ODEs) using the Faedo–Galerkin projection. The existence of solutions for the full PDE model is established by analyzing the limit of the solutions of the ODE system using a priori estimates and compactness theory. Additionally, we propose a numerical scheme for the problem based on the same approximate system. Finally, numerical simulations are performed and discussed in both physical and mathematical contexts. Full article

This paper investigates the interplay between rubber network damage, carbon black (CB) network damage, heat exchange, and voiding mechanisms in filled Styrene-butadiene rubber (SBR) under cyclic loading. To do so, three carbon black filled SBR composites, SBR5, SBR30 and SBR60 are studied. The study aims to quantify molecular damage and its role in inducing reversible or irreversible heat flow and voiding behavior to inform the design of more resilient rubber composites with improved fatigue life and thermal management capabilities. The study effectively demonstrated how increasing carbon black content, particularly in SBR60, leads to a shift from mostly reversible to irreversible and cumulative damage mechanisms during cyclic loading, as evidenced by thermal, volumetric, and electrical resistivity changes. In particular, we identify a critical mechanical energy of 7 MJ.m⁻³ associated with such transition. These irreversible changes are strongly linked to the damage and re-arrangement of the carbon black filler network, as well as the rubber chains network and the formation/growth of voids, while reversible mechanisms are likely related to rubber chains alignment associated with entropic elasticity. Full article