Search Results (1,441)

This study develops and optimizes a hybrid plant that couples a recompression sCO₂ Brayton cycle to a central-tower particle receiver with a bottoming Organic Rankine Cycle (ORC), including environmental and exergy balances. The two scenarios revealed Pareto points that raised the exergy efficiency to 0.65 in winter and reduced the fuel flow to 15 kg/s. Scenario number two achieves an overall thermal efficiency of 0.50 with total daily emissions of 2520 t CO₂ and 2850 kg NO_x, enabling nearly constant net power. Exergy destruction is concentrated in the high-temperature recuperator (HTR) and ORC turbines (27% each) and the ORC condenser (25%). Compared to a non-optimized baseline, the best solutions increased the ORC and Brayton efficiencies by 6.8–12.66% and 33.4–33.5%, respectively; cut gas-turbine power by 34% and ORC power to 10%; and lowered daily CO₂ and NO_x emissions by 52%. The gains stem from the coordinated adjustments of key levers: lower gas-turbine inlet temperature (about 10%), reduced Brayton mass flow (23%), and tuned ORC turbine inlet pressure. Full article

Objective: Although an Alberta Stroke Program Early CT Score (ASPECTS) < 7 is known to be associated with poor clinical outcomes in patients with acute ischemic stroke (AIS), the relationship between regional differences in infarct location within the ASPECTS territory and clinical outcome has not been fully clarified. The aim of this study is to evaluate the association between infarct area localization and clinical outcomes in AIS patients with large vessel occlusion and to investigate whether these regional patterns can be used to predict prognosis independently of the total ASPECTS. Methods: In this retrospective, single-center study, patients with acute ischemic stroke who had undergone non-contrast brain CT prior to endovascular thrombectomy between January 2020 and July 2023 and were found to have internal carotid artery (ICA) and/or middle cerebral artery (MCA) M1 segment occlusion were included. Patients with a premorbid modified Rankin Scale (mRS) score of 0–2 were eligible for inclusion. Patients with unavailable imaging or clinical follow-up data were excluded. Clinical outcomes were assessed using the modified Rankin Scale at 90 days. An mRS score of 0–2 was defined as a good clinical outcome, whereas an mRS score of 3–6 was defined as a poor clinical outcome. Results: A total of 283 patients were included (median age 73 years; 57.2% female), of whom 147 (51.9%) achieved a good clinical outcome. The poor outcome group had higher NIHSS scores and lower total ASPECTS values (both p < 0.001). In the regional analysis, involvement of the internal capsule (32.4% vs. 4.1%; p < 0.001) and ASPECTS M1 region (26.5% vs. 10.2%; p < 0.001) was associated with poor outcome. In multivariable analysis, internal capsule involvement (adjusted odds ratio [aOR] ≈ 12) and M1 region involvement (aOR ≈ 2.7) remained independent predictors. In the subgroup with successful recanalization, only internal capsule involvement remained an independent predictor (aOR ≈ 19). In hemisphere-stratified analyses, M1 involvement in the right hemisphere and internal capsule involvement in the left hemisphere were independently associated with poor outcome. Conclusions: The prognostic contribution of individual ASPECTS regions is not uniform in patients with acute ischemic stroke undergoing endovascular thrombectomy (EVT). In particular, involvement of the internal capsule and the M1 region shows a strong association with poor clinical outcome independent of the total ASPECTS. However, these findings suggest that regional localization alone is not sufficient for EVT patient selection. Further large-scale, multicenter studies are needed to clarify the role of regional ASPECTS assessment in clinical decision-making. Full article

To enhance the aerodynamic performance of organic Rankine cycle (ORC) turbines under increasing energy demands, surrogate-based optimization was applied to a 100 kW ORC turbine rotor. Four representative surrogate models—a radial basis neural network (RBNN), Kriging, response surface approximation (RSA), and a PRESS-based weighted (PBW) ensemble—were comparatively evaluated under identical numerical conditions. Independent optimizations of the first- and second-stage rotors enabled an examination of how different design variable space characteristics influenced surrogate predictive behavior. A fractional factorial sampling strategy was used to construct the training dataset, and learning curve analysis was conducted to assess sample size adequacy. Sensitivity estimation revealed distinct response surface characteristics between stages, allowing the interpretation of variations in surrogate stability. In both stages, geometric modifications were primarily concentrated near the outlet blade angle, identified as a dominant variable influencing efficiency. CFD validation confirmed that surrogate-based exploration successfully identified improved rotor geometries. Flow-field analysis indicated reduced entropy generation near the trailing edge region, suggesting the mitigation of aerodynamic losses. The results demonstrate that surrogate-based optimization can reliably improve turbine performance within a bounded design space, while the relative effectiveness of surrogate models depends on the sensitivity structure of the underlying problem. Full article

Digital health technologies are being used in healthcare more than ever, which has implications for the daily work of nurses. As the newest members of the nursing profession, new graduate nurses (NGNs) experience great change during the transition to practice experience. The experience of NGNs transitioning to practice while digital health technologies are being increasingly integrated is not well elucidated in the nursing literature. This proposed scoping review will address this gap and aims to explore and describe the literature involving NGNs and digital health technologies. This review will use the Joanna Briggs Institute (JBI) guidelines to search CINAHL, MEDLINE, Embase, and ERIC databases for keywords and subject headings related to the concepts of “digital health technology” and “new graduate nurses”, published between 2020 and 2026. Included articles will involve new graduate nurses with 0–12 months of experience, use digital health technology in the clinical context of nursing, and be peer-reviewed primary research. Articles will be screened and extracted using Covidence and described in line with JBI guidance and presented narratively. The findings of this scoping review will be key in positioning the transition to practice experience for NGNs in an age of digital revolution. Results will be instrumental in enhancing nursing curriculum, ensuring transition policies and procedures are supportive of developing digital health competence and assuring the delivery of better care to patients when using digital health technologies. The contribution of this review will be unique and novel in exploring NGNs and digital health, providing context for the modern experience of transition to practice. Full article

Background: Acute ischemic stroke (AIS) remains a major cause of morbidity and mortality, with an unmet need for reliable blood-based biomarkers. Glial fibrillary acidic protein (GFAP), an astrocytic structural protein, is established in hemorrhagic stroke and traumatic brain injury, but its role in AIS remains incompletely defined. Methods: In this retrospective case-control study, we enrolled AIS patients and healthy controls. Serum GFAP was measured within 24 h using the Lumipulse G1200 automated assay. Stroke severity and outcome were assessed with the National Institutes of Health Stroke Scale (NIHSS) and functional outcome with the modified Rankin Scale (mRS). Associations with clinical measures were explored using Spearman correlation, and diagnostic accuracy was determined by ROC analysis. Results: GFAP levels were significantly higher in AIS patients than controls (median 132.9 vs. 30.0 pg/mL, p < 0.001). The ROC analysis yielded an AUC of 0.88 (95% CI 0.81–0.96). A cutoff of 71 pg/mL achieved 74% sensitivity and 92% specificity, while 150 pg/mL and 32 pg/mL optimized positive and negative predictive values (95% and 96%). GFAP was correlated with stroke severity (NIHSS, ρ = 0.37–0.40, p < 0.001) and disability (mRS, ρ = 0.48–0.49, p < 0.001). No significant differences appeared across TOAST subtypes. Conclusions: Serum GFAP is significantly elevated in AIS and demonstrates strong diagnostic and prognostic value. Integration of GFAP into clinical workflows may enhance early stroke detection and outcome prediction, supporting its role as a promising biomarker in AIS. Full article

Background/Objectives: Acute ischemic stroke (AIS) is one of the leading causes of mortality worldwide and the primary cause of acquired neurological disability in adults. As part of a stroke magnetic resonance (MR) protocol, fluid-attenuated inversion recovery (FLAIR) plays an important role in the detection and assessment of the degree of leukoaraiosis (LA), while susceptibility-weighted angiography (SWAN) detects cerebral microbleeds (CMBs). The present study sought to examine the association of the degree of LA and CMBs with absolute cerebral blood flow (aCBF) values and functional outcome prediction in patients with AIS. Methods: We conducted a cross-sectional study including a total of 205 male and female patients. All of the patients underwent brain magnetic resonance imaging (MRI) examinations in the first 24 h following suspected AIS, using the stroke protocol. A modified Rankin scale (mRS) was used to evaluate the degree of functional dependence and disability three months after AIS. Results: The incidence of an unfavorable functional outcome evidently increased with more pronounced LA modalities (p < 0.05; χ² test). The Kruskal–Wallis test found a statistically significant difference in aCBF values in relation to a degree of LA (p < 0.05). As there were a small number of multiple CMBs, no statistically significant difference was found based on the detection and degree of CMBs with aCBF and functional outcome; hence, the hypothesis was not entirely confirmed. Conclusions: This study indicates the reliability of MRI application in the initial diagnostic evaluation in order to gain an additional insight into the prediction of AIS outcomes. We demonstrated that LA correlates significantly with an unfavorable functional outcome after AIS, with decreased perfusion values. On the other hand, a higher proportion of unfavorable functional outcomes was observed in patients with CMBs. However, this result was not statistically significant and should be interpreted with caution. Full article

The supercritical carbon dioxide (SCO₂) Brayton cycle presents a promising alternative to the traditional steam Rankine cycle, owing to its superior thermal efficiency, high power density, and compact design. As a key component governing system performance, the heat exchanger requires a highly compact and efficient design. This study proposes a novel additively manufactured (AM) wavy microchannel heat exchanger that achieves a compactness of 1670 m²/m³. The design incorporates adaptive flow channels to accommodate SCO₂’s density variation, along with wavy patterns and ribs to enhance thermal performance. A comprehensive fluid–thermal–mechanical coupling numerical analysis was conducted to evaluate its thermal–hydraulic and mechanical performance. Within the Reynolds number range of about 900–6000, the wavy structures improve the heat transfer rate by 21–58%, compared with the straight channel. The maximum effectiveness (ε = 0.66) occurs at a Reynolds number of 900. Compared with other heat exchangers used in the SCO₂ cycle, the overall performance of the hot and cold channels has improved by 12–44% and 3–89%, respectively. Structural analysis confirms that the average total stress under operating conditions remains below the yield strength of the Inconel 617 material, with thermal stress being the dominant contributor. This work underscores the potential of the proposed AM heat exchanger to deliver a superior combination of compactness, thermal–hydraulic performance, and structural integrity for advanced SCO₂ power cycles. Full article

The rapid evaporation of liquid droplets across a normal shock wave is a phenomenon of critical importance in advanced propulsion and clean energy systems, such as NH₃ supersonic separation. The conventional Spalding d²-law is commonly used to model such phenomena, but it is not suitable for predicting the complete vaporization of sub-micron droplets, particularly as evaporation approaches the free-molecular regime. To address this issue, this paper introduces a novel time-dependent one-dimensional CFD model, which is used to analyze the shock structure, the non-equilibrium heat and mass transfer between the liquid and gas phases, and the evolution of the droplets’ size through the shock. The model describes the evaporation of NH₃ sub-micron droplet sprays across a stationary normal shock for various fractions of the liquid phase. The Gyarmathy evaporation model is utilized to accurately account for the transition from diffusion-governed to free-molecular regimes, alongside a new two-phase Rankine–Hugoniot shock jump formulation. The study reveals the influence of a steady normal shock on the physical structure of a droplet-laden flow, including the existence of an initial droplet size swelling through the shock, and quantifies the subsequent complete evaporation of the suspended droplets. The maximum swelling throughout the shock is up to 17%, which corresponds to the case with 8% liquid phase mass fraction in the flow. The model provides acceptable accuracy in calculating the two-phase parameters in high-speed flows and can be extended for modeling more complex, multidimensional detonation and propulsion systems. Full article

The increasing regulatory pressure on the maritime sector to decarbonize, driven in part by market-based mechanisms at the European level, is accelerating the development of onboard carbon management and energy-efficiency solutions. In this context, this study evaluates an integrated architecture that combines a CO₂ liquefaction system with organic Rankine cycles. The system captures 66% of the total CO₂ emitted by ship engines and is capable of recovering up to 2600.8 kW of energy from onboard hot and cold sources. To identify the most suitable working fluids, an extensive screening of 208 low-GWP zeotropic mixtures is conducted, assessing their thermophysical behavior and energy recovery performance. A detailed thermo-economic assessment is undertaken, including the calculation of CO₂-equivalent savings, GHG abatement cost, and payback periods. To account for fuel price variability, probabilistic modelling based on Monte Carlo sampling is applied to estimate the distribution of discounted payback outcomes. The results demonstrate that Novec 649-based zeotropic mixtures combined with the proposed architecture reduce fuel consumption and enhance onboard CO₂ management while remaining safe and economically viable across a wide range of operating scenarios. Full article

This paper investigates an Organic Rankine Cycle (ORC) system for low-to-medium temperature heat recovery using comparative thermodynamic, exergoeconomic and economic modelling. A working-fluid study considering environmental and thermodynamic perspectives is conducted. A 20 kW ORC unit is tested and used as a feasibility and trend-consistency reference to support the modelling assumptions and practical operating bounds. A parametric study then examines the effects of evaporator pressure, condensation temperature, superheat, subcooling and heat-exchanger pinch-point temperature differences on net power output, first- and second-law efficiencies, total product cost and total capital investment under prescribed boundary conditions. Multi-objective optimization is applied to identify Pareto-optimal trade-offs and representative compromise solutions. Results show an intermediate evaporator pressure maximizes net power output, while lower condensation temperature generally improves efficiency; superheat has limited efficiency impact but should ensure safe operation, and a small subcooling margin (around 3 °C) mitigates cavitation risk. The best overall performance is obtained with an evaporator pinch of 3 °C and a condenser pinch of 5–9 °C; tightening pinch constraints increases required heat-transfer area and makes heat exchangers the main cost bottleneck for high-efficiency solutions. Full article

Background/Objectives: Stroke is a leading cause of long-term disability, and predicting functional outcome at discharge, such as the modified Rankin Scale (mRS), is important for guiding treatment and rehabilitation. Many existing approaches depend on advanced imaging or complex corticospinal tract (CST) segmentation from multi-shell diffusion MRI, limiting clinical feasibility. Automated lesion segmentation is also challenging due to lesion heterogeneity and MRI variability. This study proposes a clinically feasible multimodal MRI pipeline based on routine imaging. Methods: Lesion segmentation models were trained and evaluated on the ISLES 2022 dataset (250 training, 150 test cases). Zero-shot external evaluation was performed on 149 cases from ISLES 2024 using standard MRI sequences only. An ensemble of deep learning models (SEALS, NVAUTO, FACTORIZER) was evaluated on ISLES 2022, while SEALS alone was used for external testing. CST segmentation was performed using TractSeg on single-shell diffusion-weighted imaging. Imaging biomarkers included lesion volume, shape, ADC-based texture features, CST integrity, and lesion–CST overlap. These features were used to train machine learning models for binary mRS prediction at discharge. Results: The ensemble achieved a Dice score of 0.82 on ISLES 2022, while zero-shot evaluation on ISLES 2024 achieved 0.57. In exploratory analysis, CatBoost achieved the highest point estimates (accuracy 0.88, F1-score 0.87, ROC-AUC 0.83). Key predictors included lesion–CST overlap, lesion volume, surface area, dissimilarity, and contrast. Conclusions: This exploratory study demonstrates the feasibility of combining automated lesion segmentation with anatomically informed biomarkers using routine clinical MRI, supporting interpretable stroke outcome modelling and motivating future large-scale validation. Full article

This study introduces a novel transcritical CO₂ pumpless Rankine power generation cycle based on the thermal compression concept, utilizing low-temperature renewable sources. The investigated theoretical system consists of a 5 kW_e unit incorporating the aforementioned working cycle coupled with a 50 m² evacuated tube solar collector arrangement installed on the rooftop of a multifamily house in Athens, Greece. The proposed innovative configuration is parametrically analyzed for different hot water inlet temperature levels ranging from 70 to 120 °C and its efficiency is compared to the typical Organic Rankine Cycle (ORC) topology employing different conventional refrigerants. The energetic assessment is made using validated mathematical models developed in MATLAB integrating the CoolProp library. The derived results show that the investigated topology increases the performance figures compared to the baseline system for all the examined refrigerants, leading up to over 15% thermal efficiency enhancement for operation under low heat source temperatures. Finally, the year-round operation of the proposed system generates up to 5221 kWh/year for the building. Full article

Background: The relationship between inflammatory markers and cerebral small vessel disease (CSVD) in patients with acute ischaemic stroke (AIS) remains unclear. This study aimed to investigate the association between simplified inflammatory biomarkers and neuroimaging markers of CSVD. Methods: This retrospective cohort study included patients with AIS who had symptom onset within 72 h and underwent MRI brain between January 2019 and December 2023. The associations between tertiles (T) of the neutrophil-to-lymphocyte ratio (NLR) and CSVD markers were studied using multinomial logistic regression. Functional outcomes at discharge and 90 days, as measured by the modified Rankin Scale (mRS), were also evaluated. Results: A total of 299 eligible patients were included, with a mean age of 65.7 ± 13.8 years and 55.5% (166/299) were male, and categorised into three tertiles of NLR (T1: 101, T2: 101, T3: 97). Patients with a higher NLR tertile had more admission NIHSS (T3 vs. T1: 3 (2, 5) vs. 2 (1, 3), p = 0.005). NLR was associated with an increased risk of ≥5 lobar cerebral microbleeds (CMBs) in an unadjusted model (T3 vs. T1: relative risk ratio (RRR), 5.69 (95% confidence interval (CI) 1.21–26.68); p = 0.03); however, this was not significant when adjusted for potential confounders (RRR 3.86; 95% CI 0.79–18.89; p = 0.10). No significant associations were observed in the remaining neuroimaging markers of CSVD. Patients in the T2 of NLR had a higher likelihood of achieving an mRS of 0–1 at 90 days (RRR 2.16; 95% CI 1.05–4.44; p = 0.04) compared to those in T1. Conclusions: In AIS, admission NLR showed a possible association with higher lobar CMB burden in unadjusted analyses, but this was not robust after adjustment, and no consistent relationships were observed with other CSVD markers. Associations with functional outcomes were not uniform across tertiles, and the apparent benefit in the middle NLR tertile should be interpreted cautiously as a potentially non-linear or chance finding, indicating that NLR is not a reliable independent imaging or prognostic marker in this cohort. Full article

Background/Objectives: Periprocedural blood pressure influences outcomes after endovascular treatment (EVT), but the impact of pulse pressure (PP) remains unclear. We assessed associations between intraprocedural PP and clinical and radiological outcomes after EVT. Methods: We retrospectively analyzed adults with acute ischemic stroke (AIS) due to proximal anterior circulation large vessel occlusion treated with EVT under general anesthesia. Non-invasive BP was recorded every 5 min during EVT. From these recordings, we derived baseline, maximal, minimal, and median PP, PP variability indices, and cumulative time above predefined PP thresholds. The primary endpoint was poor functional outcome at 90 days (modified Rankin Scale 3–6). Secondary endpoints were final infarct volume (FIV), malignant brain edema (MBE), symptomatic intracranial hemorrhage (sICH), and hemorrhagic transformation (HT). Multivariable regression models were adjusted for established prognostic factors. Results: In the 217 patients included, higher median PP during EVT independently predicted poor functional outcome, larger FIV, MBE, and HT, but not sICH. Longer duration of PP > 50 mmHg was independently associated with poor outcome, MBE, and HT. Among other hemodynamic variables, only a >40% mean arterial pressure (MAP) drop from baseline independently predicted poor outcome. Adding median PP to the baseline multivariable model modestly increased its discriminative ability and significantly improved model fit. Conclusions: In AIS patients with proximal anterior circulation large vessel occlusion treated with EVT under general anesthesia, higher intraprocedural PP and longer exposure to elevated PP are associated with worse functional and radiological outcomes, supporting PP as a potential hemodynamic target alongside avoidance of large MAP reductions. Full article

Background/Objectives: Subarachnoid hemorrhage (SAH) is frequently complicated by cerebral vasospasm (VS). Clazosentan has reduced VS in Japanese studies but shown inconsistent efficacy in Western trials. We hypothesized that clinical and pharmacologic interactions may influence its effectiveness. Methods: We analyzed the multicenter “Database of Cohort Study for Outcome of SAH In Japan” (DCI Japan) registry, prospectively collected from 2020 to 2023, to assess associations between clazosentan use, VS prevention, functional outcomes, and potential interactions in adults with aneurysmal SAH (aSAH) treated by surgical clipping or endovascular coiling within 4 days of onset. Outcomes included angiographic VS (AVS), symptomatic VS (SVS), cerebral infarction, and modified Rankin Scale (mRS) scores at discharge and at 6 months. Predictors and interactions were first screened using univariable analysis and Light Gradient Boosting Machine, then evaluated via multivariable logistic regression. Results: Among 544 patients (mean age 65.2 ± 14.2 years; 71.5% female), 34.0% received clazosentan. AVS, SVS, and cerebral infarction occurred in 20.6%, 16.0%, and 22.4%, respectively. Poor outcomes (mRS 3–6) were observed in 48.8% at discharge and 33.7% (137/406) at 6 months. Clazosentan use was associated with reduced odds of AVS (OR 0.27, 95% CI [0.11–0.69]), SVS (OR 0.15 [0.04–0.64]), and poor 6-month outcome (OR 0.08 [0.01–0.68]). A potential interaction with nicardipine was linked to higher odds of AVS (OR 1.85 [1.43–2.65]). Conclusions: Clazosentan was associated with reduced VS and improved 6-month outcomes after aSAH, although concomitant nicardipine may attenuate its prophylactic effectiveness against AVS. Full article