Search Results (121)

Chronic obstructive pulmonary disease remains a leading cause of death worldwide, with emphysema contributing significantly to dyspnea, exercise limitation, and mortality. Bronchoscopic lung volume reduction (BLVR) using endobronchial valves (EBVs) has emerged as a minimally invasive, reversible alternative to lung volume reduction surgery for carefully selected patients with severe emphysema who remain symptomatic despite optimal medical therapy. EBVs are one-way valves placed bronchoscopically to achieve complete lobar occlusion, inducing atelectasis of the most diseased lung segments while allowing better ventilated parenchyma to expand, thereby improving respiratory mechanics and reducing hyperinflation. Landmark randomized controlled trials demonstrated that BLVR using EBVs produces significant improvements in forced expiratory volume in one second (FEV₁), exercise capacity, and quality of life comparable to surgical lung volume reduction but with reduced morbidity and mortality. Critical to treatment success is meticulous patient selection based on emphysema distribution, absence of collateral ventilation, and appropriate physiologic parameters. Pneumothorax represents the most common serious complication, occurring in approximately 26% of patients, though paradoxically, it indicates successful lobar occlusion and predicts favorable long-term outcomes. As the most extensively studied BLVR, endobronchial valve therapy represents a cornerstone intervention for appropriately selected patients with severe emphysema. Full article

In hot and humid regions, urban underground utility tunnels are susceptible to high temperature and humidity due to moist inlet air, cable heat dissipation, and limited ventilation jointly affecting the internal environment. To address this issue, an alternating ventilation strategy, in which fan operation is periodically reversed to switch between air supply and exhaust, is proposed. Compared to conventional mechanical ventilation, this strategy overcomes the constraints of unidirectional airflow and mitigates thermal and humidity stratification, with low retrofit requirements and good adaptability. Ventilation performance was evaluated using non-guarantee rates for temperature and relative humidity, i.e., the ratio of the number of measurement points where the temperature/relative humidity exceeds 40 °C/65% to the total number of measurement points in the utility tunnel (TNGR and RHNGR), non-uniformity coefficients (K_T and K_RH), and mean temperature (T_m). The alternating mode outperformed the conventional mode, reducing TNGR by 6.0% and Tm by 0.3 °C while improving temperature and humidity distributions and lowering cable temperatures. Although the reduction in T_m appears modest, it is practically meaningful because it helps weaken thermal stratification and local overheating, improves cable operating conditions, and may reduce the need for high-airflow operation when tunnel temperatures approach the permissible limit. Response surface methodology was further used to optimize the alternating ventilation parameters, indicating that the recommended fan commutation frequency is 2 under different inlet air temperatures. CFD validation confirmed the effectiveness of the optimized scheme. At an inlet air temperature of 35 °C, KRH decreased from 11.9% to 11.0% and Tm decreased from 37.5 °C to 36.9 °C. Full article

In early 2020, a respiratory virus swept across the world. The World Health Organization (WHO) confirmed pandemic status and the virus was identified as a coronavirus with superlative transmission properties. Using work from the 1950s, the WHO declared that the virus was transmitted through respiratory ‘droplets’, which were expelled by infected persons through coughing/sneezing. These would fall to the ground within 1–2 m. Scientists investigating viral transmission questioned this premise because recent work had shown that viruses populate the smallest respiratory particles, remaining airborne for much longer than larger ‘droplets’ and capable of spreading throughout the indoor environment. Advice such as handwashing, surface disinfection and social distancing was not as important as face masks and adequate indoor ventilation. People needed to know that poor ventilation constituted the highest risk for contracting the virus. Instead, homes and surfaces were disinfected and social distancing was maintained in community settings. The scientists formed a consortium named Group 36 in order to contest the WHO over airborne transmission but they could not present definitive evidence in the short term to reverse initial guidance. This account details the evolution of understanding of COVID-19 transmission and the role of Group 36 and others in challenging WHO-based policies based on dated physical science. Full article

Accurately quantifying the driving mechanisms of land surface temperature (LST) is fundamental to developing climate-resilient urban strategies. However, traditional linear models often fail to capture the complex nonlinear interactions and spatial non-stationarity inherent in urban thermal environments, especially when hindered by multicollinearity among morphological indicators. This study proposes a multi-scale spatial explainability attribution framework by integrating an XGBoost machine learning model with SHAP (SHapley Additive Explanations) to decipher the thermal dynamics of Changchun, a representative cold-region city in China. Utilizing a 500 m grid-based dataset, we incorporated 3D urban morphology (BVD), land cover (NDVI, NDWI), and socioeconomic factors. The results indicate that the XGBoost model achieves superior predictive performance (R² = 0.694) compared to traditional OLS models. SHAP global attribution identified Building Volume Density (BVD) as the primary warming driver, as its three-dimensional volume creates “thermal traps” through radiation trapping and reduced ventilation. Notably, NDVI exhibits a significant nonlinear “cooling threshold effect” at 0.3, beyond which its mitigation efficiency stagnates or even reverses due to vegetation fragmentation and heat-induced physiological stress. Furthermore, spatial mapping reveals a distinct “sign reversal” in NDWI’s impact, reflecting the dualistic thermal regulation of water bodies across different urban–rural gradients. These findings suggest that urban thermal management strategies should shift from merely restricting 2D surface occupancy (e.g., Building Density) to a more sophisticated approach focused on precisely controlling 3D volume intensity (BVD). This study provides a “point-to-area” diagnostic tool supporting a transition to spatially targeted urban planning interventions. Full article

Monolithic ceramic catalysts are a key technology for the industrial treatment of coal mine ventilation air methane (VAM). The preparation of straight-channel NiO/CeO₂ monolithic ceramic catalysts via phase inversion addresses critical bottlenecks for industrial VAM abatement. However, high-temperature sintering leads to irreversible NiO agglomeration and coarsening, severely reducing catalytic activity. In this study, an in situ reduction–oxidation reconstruction method is developed to regenerate sinter-degraded NiO. The reconstructed catalyst increases methane conversion from below 70% after sintering to over 95% at 550 °C and achieves full conversion at 600 °C. The catalyst maintains near 100% conversion during 400 h of continuous operation at 600 °C and shows no performance degradation over 15 thermal cycles. Moreover, the reconstructed catalyst exhibits excellent steam tolerance with fully reversible deactivation. The reconstructed catalyst presents a refined porous structure with BET surface area rising from 4.5 to 11.4 m² g⁻¹, an elevated Ni³⁺/Ni²⁺ ratio (1.47 to 1.97), a higher surface adsorbed oxygen proportion (36.8% to 48.7%) and significantly strengthened NiO-CeO₂ interfacial interaction. This work provides a facile and efficient in situ regeneration strategy, greatly enhancing the VAM oxidation activity and stability of sinter-degraded monolithic ceramic catalysts. Full article

Background/Objectives: Multidrug-resistant (MDR) Acinetobacter baumannii (Ab) has emerged as a significant bacterial pathogen responsible for nosocomial infections. The most common clinical manifestations of Ab infection include ventilator-associated pneumonia and catheter-related bloodstream/urinary infections. Given the extensive MDR phenotype of Ab, preventive vaccination strategies are crucial for protecting susceptible populations. Methods: We utilized immunoinformatics to identify candidate peptides containing both putative B- and T-cell epitopes from proteins associated with Ab pathogenesis. Subsequently, we designed novel Acinetobacter Multi-Epitope Vaccines (AMEVs), each comprising an Ab thioredoxin A (TrxA) leader protein, five to seven of the identified peptide antigens, and a C-terminal His(6x)-tag to facilitate protein purification. Results: Subcutaneous vaccination of C57BL/6 mice with AMEV1 or AMEV2, formulated with TiterMax adjuvant, conferred 60% and 80% protection, respectively, against intraperitoneal Ab challenge. AMEV vaccination induced a robust antibody response to each corresponding whole protein and most of its component peptides. We then constructed an improved vaccine, AMEV5, which included the Ab TrxA protein and seven confirmed B-cell epitope peptides. Subcutaneous immunization of BALB/c mice (n = 10 per group) with rAMEV5 emulsified in Adda03 adjuvant activated antigen-specific IL-5-secreting T cells and antibody-producing B cells. Evaluation of vaccine efficacy demonstrated that AMEV2- and AMEV5-immunized mice were protected from a lethal intraperitoneal Ab challenge, with survival rates of 70% and 90%, respectively. Conclusions: These study results provide insights into the application of reverse vaccinology to combat the rise of MDR Acinetobacter infection. Full article

Microclimate and built environment jointly influence outdoor activities among the elderly. However, existing studies largely focus on a single season or environmental factor, lacking a comprehensive analysis of seasonal variation and multi-factor coupling effects. This paper investigates the seasonal interaction effects of microclimate and built environment on elderly outdoor activities, with implications for elderly-friendly urban design. Using a typical residential neighbourhood in Xi’an as a case, we constructed a multi-source spatio-temporal dataset through high-density microclimate monitoring in winter and summer, fine-grained POI mapping, and computer-vision-based behavioural annotation. Generalised Additive Models (GAM) and SHAP analysis were employed for modelling and mechanism exploration. The results show that: (1) Elderly activity patterns exhibit a fundamental seasonal reversal—characterised as “sun-seeking and wind-avoiding” in winter and “shade-seeking and wind-pursuing” in summer; (2) Environmental factors exhibit marked nonlinear and threshold-dependent influences that vary by season; (3) Microclimate and built environment elements demonstrate synergistic interaction effects, especially pronounced in summer. Quantitatively, GAM and SHAP analyses indicate that the “effective service radius” of Elderly-Friendly POIs (defined as the threshold where positive influence approaches zero) contracted from approximately 45–50 m in winter to 35–40 m in summer, while their peak promotional effect occurred at 20–25 m. Positive POIs exhibited a significantly shorter influence range, and Negative POIs demonstrated negligible distance-dependent effects. This study confirms a “seasonal dynamic interaction” mechanism and proposes the adaptive design strategy of “sunlight and wind-shelter pockets—shade and ventilation corridors,” offering empirical and methodological support for climate-responsive elderly-friendly community planning. Full article

Hypoxic pulmonary vasoconstriction (HPV) is a rapid and reversible constrictor response of the pulmonary vasculature, and especially its small muscular precapillary arteries, which is initiated by episodes of local alveolar hypoxia. Acting as a protective homeostatic vasomotor mechanism, HPV enables maximal gas exchange by diverting blood from poorly ventilated alveoli into those rich in oxygen, thereby optimizing oxygen uptake and the ventilation–perfusion (V/Q) ratio so as to maintain the arterial oxygen partial pressure (P_aO₂) within the physiological range. HPV is an intrinsic mechanism of pulmonary artery smooth muscle cells (PASMCs), and requires an O₂ sensor which acts through mediator(s) to trigger effector mechanisms within these cells to evoke constriction. Whereas HPV effector mechanisms are reasonably well defined, the nature of the O₂ sensor and mediators remains in dispute, and a number of proposals have been developed to account for these. Some (but not all) of these share a focus on the concept that hypoxia activates effector mechanisms by inducing a change in the PASMC cytoplasmic redox state. Of these, the Redox Theory, first proposed by Kenneth Weir and Stephen Archer in 1995, proposes that hypoxia inhibits mitochondrial production of reactive oxygen species (ROS), thereby causing the cytoplasm to become more reduced. This inhibits ongoing vasorelaxation maintained by the opening of voltage-gated K⁺ channels. In contrast, according to the Mitochondrial ROS hypothesis, introduced by Paul Schumacker and Naveen Chandel in 2001, hypoxia increases mitochondrial ROS production, causing an oxidizing shift in the cytoplasmic redox state that activates several vasoconstricting pathways. In a third redox-based scenario, developed by Michael Wolin and Sachin Gupte, hypoxia evokes contraction by causing a fall in H₂O₂ production by NADPH oxidase and by activating the pentose phosphate pathway. These effects inhibit basal vasorelaxation maintained by the guanylate cyclase and protein kinase G and also stimulate vasoconstricting mechanisms. In this comprehensive review, we first provide a detailed summary of the key studies contributing to the development of these proposals and then subject the evidence supporting them to a critical appraisal, based in part on how well they accord with the wider literature and recent developments in our understanding of how cells shape and deploy redox mechanisms in order to regulate cell function. Full article

The overdose mortality landscape has shifted from predominantly opioid exposures to a polysubstance epidemic increasingly driven by illicit fentanyl and fentanyl analogs combined with other centrally active agents. Among the co-intoxicants, veterinary α₂-adrenoceptor (α₂AR) agonists such as xylazine have emerged as clinically confounding adulterants. Recent reports from forensic toxicology, medical examiners, and border/interdiction agencies indicate that medetomidine, a veterinary sedative racemate with the highly selective α₂AR agonist enantiomer dexmedetomidine, is increasingly being detected together with fentanyl and its analogs in seized materials and postmortem assays. Prior reviews have covered these aspects. The current review synthesizes current evidence and clinical experience relevant to fentanyl + medetomidine co-exposure-induced respiratory depression—a primary cause of death. We focus on convergent µ-opioid receptor (MOR) and α₂AR signaling within key physiological substrates, including respiratory rhythm-generating networks, ascending arousal pathways, chemosensory reflex control of ventilation, and autonomic cardiovascular regulation, integrating mechanistic pharmacology, respiratory and cardiovascular toxicology, emergency-room treatment, and emerging public-health implications. Available evidence supports a model in which combined MOR and α₂AR activation produces additive-to-synergistic suppression of ventilation and consciousness, attenuation of hypoxic ventilatory drive and CO₂ responsiveness, with marked sympatholysis manifested as bradycardia and hypotension, all of which can persist beyond presumptive opioid reversal with a MOR antagonist. We discuss the implications for prehospital and emergency care. In sum, the increasing detection of medetomidine in the illicit fentanyl supply represents an emerging and potentially high-risk co-exposure pattern that may be only partially naloxone-responsive. Lastly, we highlight potential future pharmacologic countermeasures for polysubstance overdose, such as the BK-channel antagonist ENA-001, which may address naloxone-insensitive ventilatory suppression in opioid-dominant polysubstance overdose. Full article

Modern high-speed train compartments contain intricate internal configurations. In the event of a fire emergency, the propagation velocity of flames through the passenger cabin is determined by multiple factors, including compartment design, ignition source characteristics, and airflow conditions. This study employed computational fluid dynamics (CFD) and large eddy simulation (LES) to investigate the effects of fire source power, fire source location, and longitudinal ventilation velocity on the rate of flame progression. Unlike simplified homogeneous fuel models, this study incorporates the specific heterogeneous material layout of the CR400AF to capture realistic flame spread dynamics. The simulation results reveal that, under forward ventilation conditions, the magnitude of fire power has a minimal influence on flame propagation speed. However, stronger fire sources lead to earlier initiation of flame spread along the carriage. Central positioning of the ignition source results in bidirectional flame movement toward both ends of the carriage, with faster propagation rates than those of fires originating at the extremities. Longitudinal airflow patterns significantly influence the fire dynamics. When the airflow speed within the tunnel remains below 3 m/s, the impact of longitudinal ventilation on fire propagation speed in the train is minimal under forward ventilation conditions. Conversely, in reverse-ventilation scenarios, the rate of flame advancement shows a positive correlation with increasing ventilation speed. Nevertheless, once tunnel ventilation velocities exceed 3 m/s, combustion propagation within high-speed rail carriages becomes impossible due to intact windows, which create oxygen-deficient conditions that prevent the development of fire. This paper investigates the heat release rate and spread process of vehicle fires. It comprehensively considers the effects of fire source power, fire source location, and longitudinal ventilation rate on the rate of spread. The research results provide data support for the fire-resistant design of rail transit vehicles and for the formulation of emergency evacuation strategies for different fire scenarios, which are vital for enhancing rail vehicle fire safety and ensuring personnel evacuation safety. Full article

The Church of San Juan del Hospital in Valencia (Spain) is a Gothic church whose main architectural feature—the western façade—remained unresolved, posing structural and compositional challenges. The intervention addressed this issue while preserving the historical integrity of the building and its heritage context. A systematic methodology was applied, following principles of reversibility, sustainability, and compatibility with medieval ribbed-vault construction. The project resolved five key aspects: completion of the nave’s façade, coverage of the former atrium remains, access from the north courtyard, compositional coherence of the west courtyard front, and integration of the church and museum entrances. Contemporary materials and techniques, including aluminum, recycled wood, and handmade ceramic brick, were selected to harmonize with historic stonework, ensure durability, and minimize environmental impact. Design strategies guided visual perception, emphasizing the lower façade and resolving dispersive compositional elements, while creating functional spaces for ventilation, climate control, and circulation. This intervention demonstrates how a methodical, heritage-sensitive approach can solve complex architectural problems, combining innovation with historical authenticity, and enhancing both the functionality and aesthetic experience of the Church of San Juan del Hospital. Full article

Background/Objectives: Venovenous extracorporeal membrane oxygenation (VV ECMO) supports reversible respiratory failure when mechanical ventilation fails. Technological advances and specialized teams now enable ECMO initiation at referring centers, even for high-risk transports. This study aimed to evaluate the safety of pediatric patients on ECMO support during medical transfer, based on a single-center experience and a systematic review of the literature. Methods: A retrospective analysis was conducted on all pediatric patients supported with ECMO transferred from regional hospitals to our university hospital (January 2023–September 2025), focusing on transport-related mortality and morbidity. We also performed a systematic review of original articles (2015–2025) using the PubMed, Embase, and Cochrane databases. Results: Fourteen critically ill children with a median age of 16 months (range: 2 months to 11 years) and acute respiratory failure were transferred to our hospital’s Intensive Therapy Unit. All transported patients in the local cohort were supported with VV ECMO. Transport distances ranged from 5 to 520 km (median: 151 km). No mortality or serious adverse events occurred during transfer. Two technical issues were noted. In the systematic review, 14 articles met the inclusion criteria, reporting a total of 900 transfers, mainly primary ECMO initiations (779–86.6%). The number of ground transports was 337, which accounted for 37.4%. Adverse events were reported in 252 out of 900, which was 28%. One death during transport was reported (mortality: 1‰). Conclusions: All transports were safely performed by our experienced multidisciplinary mobile ECMO team. Both our experience and literature review confirmed low mortality in pediatric ECMO transport, despite potential life-threatening adverse events. Full article

Fast-track extubation has emerged as a vital component of Enhanced Recovery After Surgery pathways, designed to optimize recovery and resource utilization after cardiac surgery, contrasting with traditional prolonged ventilation. This review explores the evidence supporting fast-track extubation, detailing patient selection criteria based on preoperative risk factors and functional status and outlining perioperative management strategies. It synthesizes findings from various studies, including randomized controlled trials, retrospective studies, and meta-analyses, focusing on intraoperative techniques such as low-dose opioids, neuromuscular blockade reversal, controlled cardiopulmonary bypass duration, judicious inotrope use, and minimal transfusion, alongside structured postoperative protocols emphasizing early sedative weaning and spontaneous breathing trials. Results demonstrate that fast-track extubation decreases intensive care unit stay, reduces costs and ventilator-associated complications, with a safety comparable to conventional care. Prolonged cardiopulmonary bypass time, dependency on inotropes, and intraoperative blood transfusions are identified as critical predictors of fast-track extubation failure. In conclusion, the successful implementation of fast-track extubation protocols requires a collaborative, multidisciplinary approach, proving essential for improving patient outcomes, minimizing complications such as postoperative delirium, and enhancing hospital efficiency in cardiac surgery. Further research should aim to refine patient selection and standardize protocols across healthcare systems. Full article

Background/Objectives: The physiological ventilation–perfusion ratio (V/Q) in the upper pulmonary field is >3 and in the lower pulmonary field it is <1 due to the effect of gravity when the body is in an upright position. Pneumonectomy leads to significant changes in ventilation and perfusion conditions. The aim of this study was to evaluate perfusion and ventilation after pneumonectomy complicated by pleural empyema, including the relationship between surgical outcomes, sex, and time from pneumonectomy. Methods: The study group included 30 patients (25 men, 5 women) who underwent pneumonectomy complicated by pleural empyema. Lung function was assessed using ventilation–perfusion scintigraphy. Twenty-one patients were assessed within 5 years after pneumonectomy and nine patients >5 years after pneumonectomy. Results: Average flow was 21.1% in the upper field, 47.8% in the middle field, and 30.35% in the lower field. The mean perfusion value was significantly higher in the lower field of the right lung than in the lower field of the left lung (33.35 vs. 28.05, p = 0.001). Average ventilation was 17.21% in the upper field, 46.73% in the middle field, and 34.28% in the lower field. The mean V/Q in the upper field was in the range of 0.81–0.87, but it reached approximately 1 (0.96–1) in the middle field and exceeded 1 (1.05–1.25) in the lower field. Conclusions: Pneumonectomy led to increased perfusion in the upper pulmonary field and increased ventilation in the lower pulmonary field compared to the literature for patients with the two lungs (the two-lung system), with a reversal of the V/Q between the upper and lower field. Full article

This study systematically investigates the velocity characteristics and coupling mechanisms of tunnel flow fields under the interactions of natural wind, traffic wind, mechanical ventilation, and structural factors (such as transverse passages and relative positions between vehicles and fans). Using CFD simulations combined with turbulence model analyses, the flow behaviors under different coupling scenarios are explored. The results show that: (1) Under natural wind conditions, transverse passages act as key pressure boundaries, reshaping the longitudinal wind speed distribution into a segmented structure of “disturbance zones (near passages) and stable zones (mid-regions)”, with disturbances near passages showing “amplitude enhancement and range contraction” as natural wind speed increases. (2) The coupling of natural wind and traffic wind (induced by moving vehicles) generates complex turbulent structures; vehicle motion forms typical flow patterns including stagnation zones, high-speed bypass flows, and wake vortices, while natural wind modulates the wake structure through momentum exchange, affecting pollutant dispersion. (3) When natural wind, traffic wind, and mechanical ventilation are coupled, the flow field is dominated by momentum superposition and competition; adjusting fan output can regulate coupling ranges and turbulence intensity, balancing energy efficiency and safety. (4) The relative positions of vehicles and fans significantly affect flow stability: forward positioning leads to synergistic momentum superposition with high stability, while reverse positioning induces strong turbulence, compressing jet effectiveness and increasing energy dissipation. This study reveals the intrinsic laws of tunnel flow field evolution under multi-factor coupling, providing theoretical support for optimizing tunnel ventilation system design and dynamic operation strategies. Full article