BACKGROUND Acute respiratory distress syndrome(ARDS)is a critical condition characterized by acute hypoxemia,non-cardiogenic pulmonary edema,and decreased lung compliance.The Berlin definition,updated in 2012,classifi...BACKGROUND Acute respiratory distress syndrome(ARDS)is a critical condition characterized by acute hypoxemia,non-cardiogenic pulmonary edema,and decreased lung compliance.The Berlin definition,updated in 2012,classifies ARDS severity based on the partial pressure of arterial oxygen/fractional inspired oxygen fraction ratio.Despite various treatment strategies,ARDS remains a significant public health concern with high mortality rates.AIM To evaluate the implications of driving pressure(DP)in ARDS management and its potential as a protective lung strategy.METHODS We conducted a systematic review using databases including EbscoHost,MEDLINE,CINAHL,PubMed,and Google Scholar.The search was limited to articles published between January 2015 and September 2024.Twenty-three peer-reviewed articles were selected based on inclusion criteria focusing on adult ARDS patients undergoing mechanical ventilation and DP strategies.The literature review was conducted and reported according to PRISMA 2020 guidelines.RESULTS DP,the difference between plateau pressure and positive end-expiratory pressure,is crucial in ARDS management.Studies indicate that lower DP levels are significantly associated with improved survival rates in ARDS patients.DP is a better predictor of mortality than tidal volume or positive end-expiratory pressure alone.Adjusting DP by optimizing lung compliance and minimizing overdistension and collapse can reduce ventilator-induced lung injury.CONCLUSION DP is a valuable parameter in ARDS management,offering a more precise measure of lung stress and strain than traditional metrics.Implementing DP as a threshold for safety can enhance protective ventilation strategies,po-tentially reducing mortality in ARDS patients.Further research is needed to refine DP measurement techniques and validate its clinical application in diverse patient populations.展开更多
BACKGROUND Many studies have revealed a link between non-alcoholic fatty liver disease(NA-FLD)and coronavirus disease 2019(COVID-19),making understanding the relationship between these two conditions an absolute requi...BACKGROUND Many studies have revealed a link between non-alcoholic fatty liver disease(NA-FLD)and coronavirus disease 2019(COVID-19),making understanding the relationship between these two conditions an absolute requirement.AIM To provide a qualitative synthesis on the currently present data evaluating COVID-19 and NAFLD.METHODS This systematic review was conducted in accordance with the guidelines pro-vided by preferred reporting items for systematic reviews and meta-analyses and the questionnaire utilized the population,intervention,comparison,and outcome framework.The search strategy was run on three separate databases,PubMed/MEDLINE,Scopus,and Cochrane Central,which were systematically searched from inception until March 2024 to select all relevant studies.In addition,ClinicalTrials.gov,Medrxiv.org,and Google Scholar were searched to identify grey literature.RESULTS After retrieval of 11 studies,a total of 39282 patients data were pooled.Mortality was found in 11.5%and 9.4%of people in NAFLD and non-NAFLD groups.In all,23.2%of NAFLD patients and 22%of non-NAFLD admissions diagnosed with COVID-19 were admitted to the intensive care unit,with days of stay varying.Ventilatory support ranged from 5%to 40.5%in the NAFLD cohort and from 3.1%to 20%in the non-NAFLD cohort.The incidence of acute liver injury showed significance.Clinical improvement on days 7 and 14 between the two classifications was significant.Hospitalization stay ranged from 9.6 days to 18.8 days and 7.3 days to 16.4 days in the aforementioned cohorts respectively,with 73.3%and 76.3%of patients being discharged.Readmission rates varied.CONCLUSION Clinical outcomes except mortality consistently showed a worsening trend in patients with NAFLD and concomitant COVID-19.Further research in conducting prospective longitudinal studies is essential for a more powerful conclusion.展开更多
This paper is based on the rainwater collection project in the retrofit of the Dongyi teaching block in Zhejiang University Xixi Campus.The analysis incorporates the local meteorological data, recycling water utilizat...This paper is based on the rainwater collection project in the retrofit of the Dongyi teaching block in Zhejiang University Xixi Campus.The analysis incorporates the local meteorological data, recycling water utilization, and precipitation adjustment.The rainwater collection system in this program also adds the condensation water from the heating, ventilation and air conditioning （ HVAC） system and the concentration from the reverse-osmosis system used for watering greens and supplying waterscapes.By calculating, the quantity of the HVAC condensation water in summer is 3.48 m3/d, and the quantity of the reverse-osmosis concentrated water is 198 to 396 L/d.This method solves the water shortage caused by high evaporation in summer and low precipitation in winter.Supported by empirical monitoring data, the proposed method significantly increases the economic efficiency of the system during the summer period.展开更多
https://www.sciencedirect.com/journal/energy-and-buildings/vol/342/suppl/C Volume 342,1 September 2025[OA](1)Experimental validation of neural network-based prediction of natural ventilation bulk airflow rate by Jo ao...https://www.sciencedirect.com/journal/energy-and-buildings/vol/342/suppl/C Volume 342,1 September 2025[OA](1)Experimental validation of neural network-based prediction of natural ventilation bulk airflow rate by Jo ao Carlos Sim oes,Guilherme Carrilho da Graca,Article115871Abstract:To fully exploit natural ventilation(NV)as an energysaving strategy in mixed-mode buildings,accurate real-time prediction of NV airflow rates is essential.Current approaches for NV airflow rates prediction often rely heavily on expertise knowledge and computationally demanding methods such as Computational Fluid Dynamics(CFD)as well as expensive and complex direct airflow measurements.展开更多
BACKGROUND A major cause of mortality in the coronavirus disease 2019(COVID-19)pandemic was acute respiratory distress syndrome(ARDS).Currently,moderate to severe ARDS induced by COVID-19(COVID ARDS)and other viral an...BACKGROUND A major cause of mortality in the coronavirus disease 2019(COVID-19)pandemic was acute respiratory distress syndrome(ARDS).Currently,moderate to severe ARDS induced by COVID-19(COVID ARDS)and other viral and non-viral etiologies are treated by traditional ARDS protocols that recommend 12-16 hours of prone position ventilation(PPV)with neuromuscular blocking agents(NMBA)and a trial of inhaled vasodilators(IVd)if oxygenation does not improve.However,debate on the efficacy of adjuncts to PPV and low tidal volume ventilation persists and evidence about the benefits of IVd/NMBA in COVID ARDS is sparse.In our multi-center retrospective review,we evaluated the impact of PPV,IVd,and NMBA on outcomes and lung mechanics in COVID ARDS patients with moderate to severe ARDS.AIM To evaluate the impact of PPV used alone or in combination with pulmonary IVd and/or NMBA in mechanically ventilated patients with moderate to severe ARDS during the COVID-19 pandemic.METHODS A retrospective study at two tertiary academic medical centers compared outcomes between COVID ARDS patients receiving PPV and patients in the supine position.PPV patients were divided based on concurrent use of ARDS adjunct therapies resulting in four subgroups:(1)PPV alone;(2)PPV and IVd;(3)PPV and NMBA;and(4)PPV,IVd,and NMBA.Primary outcomes were hospital and intensive care unit(ICU)length of stay(LOS),mortality,and venovenous extracorporeal membrane oxygenation(VV-ECMO)status.Secondary outcomes included changes in lung mechanics at 24-hour intervals for 7 days.RESULTS Total 114 patients were included in this study.Baseline respiratory parameters and Sequential Organ Failure Assessment scores were significantly worse in the PPV group.ICU LOS and LOS were significantly longer for patients who were proned,but no mortality benefit or difference in VV-ECMO status was found.Among the subgroups,no difference in primary outcomes were found.In the secondary analysis,PPV was associated with a significant improvement in arterial oxygen partial pressure(PaO_(2))/fractional inspired oxygen(FiO_(2))(P/F)ratio from day 1 to day 4(P<0.05)and higher driving pressures day 5 to day 7(P<0.05).The combination of PPV and IVd together resulted in improvements in P/F ratio from day 1 to day 7 and plateau pressure on day 4 and day 6(P<0.05).PPV with NMBA was not associated with improvements in any of the secondary outcomes.The use of all three rescue therapies together resulted in improvements in lung compliance on day 2(P<0.05)but no other improvements.CONCLUSION In mechanically ventilated patients diagnosed with moderate to severe COVID ARDS,PPV and PPV with the addition of IVd produced a significant and sustained increase in P/F ratio.The combination of PPV,IVd and NMBA improved compliance however this did not reach significance.Mortality and LOS did not improve with adjunct therapies.Further research is warranted to determine the efficacy of these therapies alone and in combination in the treatment of COVID ARDS.展开更多
BACKGROUND:In this study,we aimed to evaluate the impact of mechanical ventilator(MV)utilizaton during cardiopulmonary resuscitation(CPR)on out-of-hospital cardiac arrest(OHCA)patient clinical outcomes in the emergenc...BACKGROUND:In this study,we aimed to evaluate the impact of mechanical ventilator(MV)utilizaton during cardiopulmonary resuscitation(CPR)on out-of-hospital cardiac arrest(OHCA)patient clinical outcomes in the emergency department.METHODS:This single-centered,retrospective,case-control study analyzed electronic medical records.Patients aged>18 years with non-traumatic OHCA who were treated at an emergency medical center between January 2019 and December 2023 were included.These patients were accessed according to the ventilatory method used:MV ventilation(volume control,tidal volume 6-8 mL/kg,frequency 10 beat per minute,inspiratory time 1 s)and manual resuscitator bag valve(BV)ventilation.The primary outcome was the return of spontaneous circulation(ROSC).After 1:1 propensity score matching,the clinical outcomes were analyzed.RESULTS:A total of 649 patients were enrolled in this study.Before matching,the clinical outcomes and pneumothorax incidence did not differ between the MV and BV groups.After 1:1 matching between the two groups using propensity scores,522 patients(261 MV and 261 BV)were analyzed.Propensity score matching yielded an adequate balance(standardized mean difference<0.10)for all covariates.The estimated odds ratio(OR)for ROSC was 1.23(95%confidence interval[CI]:0.85-1.77;P=0.267),for survival at hospital admission was 1.02(95%CI:0.68-1.53;P=0.918),for survival at hospital discharge was 2.31(95%CI:1.10-5.20;P=0.033),and for good neurologic outcome was 2.56(95%CI:0.84-9.43;P=0.116).CONCLUSION:In patients with OHCA admitted to the emergency department,MV ventilation during CPR showed clinical outcomes similar to those of BV ventilation in most measures.However,survival at hospital discharge was significantly higher in the MV group,suggesting potential benefits of MV use in selected patients.展开更多
Prediction of weaning success from invasive mechanical ventilation remains a challenge in everyday clinical practice.Several prediction scores have been developed to guide success during spontaneous breathing trials t...Prediction of weaning success from invasive mechanical ventilation remains a challenge in everyday clinical practice.Several prediction scores have been developed to guide success during spontaneous breathing trials to help with weaning decisions.These scores aim to provide a structured framework to support clinical judgment.However,their effectiveness varies across patient populations,and their predictive accuracy remains inconsistent.In this review,we aim to identify the strengths and limitations of commonly used clinical prediction tools in assessing readiness for ventilator liberation.While scores such as the Rapid Shallow Breathing Index and the Integrative Weaning Index are widely adopted,their sensitivity and specificity often fall short in complex clinical settings.Factors such as underlying disease pathophysiology,patient characteristics,and clinician subjectivity impact score performance and reliability.Moreover,disparities in validation across diverse populations limit generalizability.With growing interest in artificial intelligence(AI)and machine learning,there is potential for enhanced prediction models that integrate multidimensional data and adapt to individual patient profiles.However,current AI approaches face challenges related to interpretability,bias,and ethical implementation.This paper underscores the need for more robust,individualized,and transparent prediction systems and advocates for careful integration of emerging technologies into clinical workflows to optimize weaning success and patient outcomes.展开更多
BACKGROUND Gastroesophageal reflux disease(GERD)is common among neonates,particularly those requiring mechanical ventilation.Pepsin,a reliable marker of gastric aspi-ration,may help detect GER episodes in ventilated n...BACKGROUND Gastroesophageal reflux disease(GERD)is common among neonates,particularly those requiring mechanical ventilation.Pepsin,a reliable marker of gastric aspi-ration,may help detect GER episodes in ventilated neonates and assess associated clinical outcomes.AIM To determine the incidence of GERD,associated risk factors,and morbidities among full-term mechanically ventilated neonates by detecting pepsin in endo-tracheal aspirates(ETA).METHODS This study included 97 full-term neonates admitted to the neonatal intensive care unit at Cairo University Hospitals from April 2023 to March 2024.ETA samples were collected at three intervals:Immediately post-intubation(Sample A),48 hours after intubation(Sample B),and just before extubation(Sample C).Pepsin concentration was measured using enzyme-linked immunosorbent assay.Clinical data,including hospital stay duration and feeding parameters,were correlated with pepsin levels.RESULTS Pepsin was detected in 76(78.4%)of Sample A,78(81.3%)of Sample B,and 47(68.1%)of Sample C.A significant positive correlation was found between pepsin levels and FiO_(2) in Sample B(r=0.203,P=0.047).Prolonged hospital stay was also associated with pepsin detection in Samples B and C(P<0.05).A negative correlation was observed between feeding amount and pepsin levels across all samples(P<0.05).CONCLUSION The incidence of GERD in full-term mechanically ventilated neonates is high,correlating with pepsin levels,FiO_(2),feeding intolerance,and hospital stay,highlighting the importance of early detection.展开更多
BACKGROUND Lung ultrasonography is being increasingly used in mechanically ventilated patients to evaluate the lung aeration during incremental positive end expiratory pressure(PEEP)adjustments and to evaluate the wea...BACKGROUND Lung ultrasonography is being increasingly used in mechanically ventilated patients to evaluate the lung aeration during incremental positive end expiratory pressure(PEEP)adjustments and to evaluate the weaning process from mechanical ventilation.The effects of PEEP may vary across different lung pathologies and may not consistently correlate with changes in lung aeration as assessed by lung ultrasound scores(LUSs).AIM To assess the role of lung ultrasonography in evaluating lung aeration during the application of PEEP in mechanically ventilated patients with various lung pathologies.METHODS An observational study was conducted over 18 months in a tertiary care hospital.Patients of both genders,aged between 18-75 years,who had been admitted to the intensive care unit,and required mechanical ventilation,were studied.A standard ventilatory strategy was used and incremental levels of PEEP[5,10,and 15 cm water(H_(2)O)]were applied.Baseline characteristics,including oxygen saturation(SpO2),LUS,mean arterial pressure(MAP),heart rate(HR),and their changes with incremental PEEP levels,were recorded and analyzed.RESULTS In this study,45.9%of patients required a PEEP of 5 cm H_(2)O to achieve the endpoint of lung aeration(LUS of 0).In addition,86.5% and 13.5% of patients reached the endpoint of lung aeration at PEEP levels of 10 and 15 cm H_(2)O,respectively.The proportion of patients with higher lung scores decreased significantly with increasing PEEP levels(P<0.001 for 5 and 10 cm H_(2)O and P=0.032 for 15 cm H_(2)O).SpO2 increased significantly with higher PEEP levels(P<0.001),confirming the effectiveness of PEEP in improving oxygenation.The results also revealed a significant increase in HR and a decrease in MAP following the application of higher PEEP levels.CONCLUSION Increasing PEEP levels in mechanically ventilated patients improves lung aeration,which can be effectively assessed using bedside lung ultrasonography.展开更多
Mechanical ventilation is a specialized oxygen therapy and life support technology with significant importance for critically ill patients. In fact, 40%–66% of patients in the intensive care unit(ICU) require mechani...Mechanical ventilation is a specialized oxygen therapy and life support technology with significant importance for critically ill patients. In fact, 40%–66% of patients in the intensive care unit(ICU) require mechanical ventilation.^([1,2]) However, the mechanical ventilation can lead to ventilatorassociated lung injury(VALI),^([3]) ultimately resulting in difficulties in weaning from mechanical ventilation,prolonged hospital stays, and even increased mortality.展开更多
The longitudinal ventilation strategy is commonly used for road tunnels in urban environment in Sweden.This is partly due to how tunnels in urban environment was planned and designed before the EU Directive[1](2004/54...The longitudinal ventilation strategy is commonly used for road tunnels in urban environment in Sweden.This is partly due to how tunnels in urban environment was planned and designed before the EU Directive[1](2004/54/EC)came in place.Even in new tunnels both to practical and economic reasons the use of longitudinal ventilation has been an outspoken demand from the Swedish road authority,SRA.Swedish law[2]requires that a risk analysis is carried out to demonstrate that an acceptable level of risk is achieved in the tunnels with longitudinal ventilation if there is a risk of queues.Otherwise transverse or semi-transverse ventilation strategy shall be used.During recent development,or a late awakening,it is clear that dense populated areas in Sweden will experience queues.This threatens the foundation of the Swedish modern tunnel safety concept which calls for enhancement.This paper presents the risk-reducing effect of three alternative strategies,enhancements package,focusing on evacuation safety for road users.It is a combination of traffic management,fixed firefighting systems,reduced distance between escape routes and regulation of traffic with dangerous goods.In addition,it provides a comprehensive review of safety system details,combined with a longitudinal ventilation concept.展开更多
With different structural forms of ventilation pipes have various attenuation effects on incident shock waves while meeting ventilation requirements.The attenuation mechanism and the propagation law of shock waves in ...With different structural forms of ventilation pipes have various attenuation effects on incident shock waves while meeting ventilation requirements.The attenuation mechanism and the propagation law of shock waves in ventilation pipes of different structures are investigated by experiments and numerical simulations.Furthermore,for the same structure,the effects of peak pressure and positive pressure time on the attenuation rate are discussed.It is found that the attenuation rate increases with the incident shock wave pressure,and the shock wave attenuation rate tends to reach its limiting value k for the same structure and reasonably short positive pressure time.Under the same conditions,the attenuation rate is calculated using the pressure of the shock wave as follows:diffusion chamber pipe,branch pipe and selfconsumption pipe;the attenuation rate per unit volume is calculated as follows:self-consumption pipe,branch pipe and diffusion chamber pipe.In addition,an easy method is provided to calculate the attenuation rate of the shock wave in single and multi-stage ventilation pipes.Corresponding parameters are provided for various structures,and the margin of error between the formulae and experimental results is within 10%,which is significant for engineering applications.展开更多
Objective:To explore the role of lung ultrasound combined with multi-organ evaluation in assessing the risk of weaning from mechanical ventilation(MV)in severe patients.Methods:A retrospective analysis was conducted o...Objective:To explore the role of lung ultrasound combined with multi-organ evaluation in assessing the risk of weaning from mechanical ventilation(MV)in severe patients.Methods:A retrospective analysis was conducted on 60 severe patients admitted to the hospital from December 2022 to December 2024,all of whom underwent MV treatment.Based on weaning status,thirty-eight patients were successfully weaned(success group),and 22 patients failed weaning(failure group).All patients underwent lung ultrasound and multi-organ evaluation.The parameter differences between the two groups were compared,risk factors for weaning risk were evaluated,and a receiver operating characteristic curve(ROC)was drawn to assess the predictive value of lung ultrasound combined with multi-organ evaluation for weaning risk.Results:The lung ultrasound score(LUS)of the success group was lower than that of the failure group,the left ventricular ejection fraction(LVEF)was higher than that of the failure group,and the diaphragmatic excursion(DE)and diaphragmatic thickening fraction(DTF)were higher than those of the failure group(P<0.05).Multifactor analysis showed that LUS was a risk factor for weaning risk,while LVEF,DE,and DTF were protective factors(P<0.05).The ROC showed that the area under the curve(AUC)of a single parameter for weaning risk was smaller than that of the combined parameters(P<0.05).Conclusion:Lung ultrasound combined with multi-organ evaluation can predict the weaning risk of severe patients undergoing MV treatment,and the diagnostic efficiency of multiple parameters combined evaluation is higher.展开更多
Indoor air quality(IAQ)is often overlooked,yet a poorly maintained environment can lead to significant health issues and reduced concentration and productivity in work or educational settings.This study presents an in...Indoor air quality(IAQ)is often overlooked,yet a poorly maintained environment can lead to significant health issues and reduced concentration and productivity in work or educational settings.This study presents an innovative control system for mechanical ventilation specifically designed for university classrooms,with the dual goal of enhancing IAQ and increasing energy efficiency.Two classrooms with distinct construction characteristics were analyzed:one with exterior walls and windows,and the other completely underground.For each classroom,a model was developed using DesignBuilder software,which was calibrated with experimental data regarding CO_(2) concentration,temperature,and relative humidity levels.The proposed ventilation system operates based on CO_(2) concentration,relative humidity,and potential for free heating and cooling.In addition,the analysis was conducted for other locations,demonstrating consistent energy savings across different climates and environments,always showing an annual reduction in energy consumption.Results demonstrate that mechanical ventilation,when integrated with heat recovery and free cooling strategies,significantly reduces energy consumption by up to 25%,while also maintaining optimal CO_(2) levels to enhance comfort and air quality.These findings emphasize the essential need for well-designed mechanical ventilation systems to ensure both psychophysical well-being and IAQ in enclosed spaces,particularly in environments intended for extended occupancy,such as classrooms.Furthermore,this approach has broad applicability,as it could be adapted to various building types,thereby contributing to sustainable energy management practices and promoting healthier indoor spaces.This study serves as a model for future designs aiming to balance energy efficiency with indoor air quality,especially relevant in the post-COVID era,where the importance of indoor air quality has become more widely recognized.展开更多
BACKGROUND For over half a century,the administration of maternal corticosteroids before anticipated preterm birth has been regarded as a cornerstone intervention for enhancing neonatal outcomes,particularly in preven...BACKGROUND For over half a century,the administration of maternal corticosteroids before anticipated preterm birth has been regarded as a cornerstone intervention for enhancing neonatal outcomes,particularly in preventing respiratory distress syndrome.Ongoing research on antenatal corticosteroids(ACS)is continuously refining the evidence regarding their efficacy and potential side effects,which may alter the application of this treatment.Recent findings indicate that in resource-limited settings,the effectiveness of ACS is contingent upon meeting specific conditions,including providing adequate medical support for preterm newborns.Future studies are expected to concentrate on developing evidence-based strategies to safely enhance ACS utilization in low-and middle-income countries.AIM To analyze the clinical effectiveness of antenatal corticosteroids in improving outcomes for preterm newborns in a tertiary care hospital setting in Kazakhstan,following current World Health Organization guidelines.METHODS This study employs a comparative retrospective cohort design to analyze single-center clinical data collected from January 2022 to February 2024.A total of 152 medical records of preterm newborns with gestational ages between 24 and 34 weeks were reviewed,focusing on the completeness of the ACS received.Quantitative variables are presented as means with standard deviations,while frequency analysis of qualitative indicators was performed using Pearson'sχ^(2) test(χ^(2))and Fisher's exact test.If statistical significance was identified,pairwise comparisons between the three observation groups were conducted using the Bonferroni correction.RESULTS The obtained data indicate that the complete implementation of antenatal steroid prophylaxis(ASP)improves neonatal outcomes,particularly by reducing the frequency of birth asphyxia(P=0.002),the need for primary resuscitation(P=0.002),the use of nasal continuous positive airway pressure(P=0.022),and the need for surfactant replacement therapy(P=0.038)compared to groups with incomplete or no ASP.Furthermore,complete ASP contributed to a decrease in morbidity among preterm newborns(e.g.,respiratory distress syndrome,intrauterine pneumonia,cerebral ischemia,bronchopulmonary dysplasia,etc.),improved Apgar scores,and reduced the need for re-intubation and the frequency of mechanical ventilation.However,it was associated with an increased incidence of uterine atony in postpartum women(P=0.0095).CONCLUSION In a tertiary hospital setting,the implementation of ACS therapy for pregnancies between 24 and 34 weeks of gestation at high risk for preterm birth significantly reduces the incidence of neonatal complications and related interventions.This,in turn,contributes to better outcomes for this cohort of children.However,the impact of ACS on maternal outcomes requires further thorough investigation.展开更多
Ventilation systems are critical for improving the cabin environment in high-speed trains,and their interest has increased significantly.However,whether air supply non-verticality deteriorates the cabin air environmen...Ventilation systems are critical for improving the cabin environment in high-speed trains,and their interest has increased significantly.However,whether air supply non-verticality deteriorates the cabin air environment,and the flow mechanism behind it and the degree of deterioration are not known.This study first analyzes the interaction between deflection angle and cabin flow field characteristics and ventilation performance.The results revealed that the interior temperature and pollutant concentration decreased slightly with increasing deflection angle,but resulted in significant deterioration of thermal comfort and air quality.This is evidenced by an increase in both draught rate and non-uniformity coefficient,an increase in the number of measurement points that do not satisfy the micro-wind speed and temperature difference requirements by about 5% and 15%,respectively,and an increase in longitudinal penetration of pollutants by a factor of about 5 and the appearance of locking regions at the ends of cabin.The results also show that changing the deflection pattern only affects the region of deterioration and does not essentially improve this deterioration.This study can provide reference and help for the ventilation design of high-speed trains.展开更多
Heat Recovery Ventilators(HRVs)are essential for improving indoor air quality(IAQ)and reducing energy consumption in residential buildings situated in cold climates.This study considers the efficiency and performance ...Heat Recovery Ventilators(HRVs)are essential for improving indoor air quality(IAQ)and reducing energy consumption in residential buildings situated in cold climates.This study considers the efficiency and performance optimization of HRVs under cold climatic conditions,where conventional ventilation systems increase heat loss.A comprehensive numerical model was developed using COMSOL Multiphysics,integrating fluid dynamics,heat transfer,and solid mechanics to evaluate the thermal efficiency and structural integrity of an HRV system.The methodology employed a detailed geometry with tetrahedral elements,temperature-dependent material properties,and coupled governing equations solved under Tehran-specific boundary conditions.A multi-objective optimization was implemented in the framework of the Nelder-Mead simplex algorithm,targeting the maximization of the average outlet temperature and minimization of the maximum von Mises thermal stress,with inlet flow velocity as the design variable(range:0.5–1.2m/s).Results indicate an optimal velocity of 0.51563 m/s,achieving an average outlet temperature of 289.44 K and maximum von Mises stress of 221 MPa,validated through mesh independence and detailed contour analyses of temperature,velocity,and stress distributions.展开更多
During the train meeting events,train equipment compartments are exposed to the worst pressure changes,potentially affecting the ventilation performance of equipment,particularly for electrical facilities equipped wit...During the train meeting events,train equipment compartments are exposed to the worst pressure changes,potentially affecting the ventilation performance of equipment,particularly for electrical facilities equipped with independent air ducts.In this paper,a two-step method is used for numerical computation:(1)obtaining the temporal and spatial transient node data of the flow field sections during the train-passing simulation and(2)using the data as the input data for the equipment compartment simulation.In addition,this paper also compares the difference in equipment ventilation between the single-train and trainpassing scenarios in real vehicle tests.The results indicate that the primary factors influencing ventilation effectiveness are the aerodynamic compression and deceleration of airflow induced by the other train's nose,as well as the instability of the external flow field in the wake of the other train.During train crossing,the air is forced into the air duct,with a maximum ratio of the airflow in-duct to the airflow out-duct reaching 3.2.The average mass flow falls below the rated mass flow for the converter.Compared to the rated air volume of converter,the maximum suppression rates obtained from testing and simulation are-24.5%and-16.8%,respectively.Compared to the single-train operation,the maximum suppression rates obtained from testing and simulation are-15%and-18%,respectively.These findings provide valuable insights into the design and operation of high-speed trains.展开更多
The preservation condition of historical buildings is closely related to their ventilation environment.This study focuses on the rock temples in Wudang Mountain,specifically comparing the ventilation conditions of Yin...The preservation condition of historical buildings is closely related to their ventilation environment.This study focuses on the rock temples in Wudang Mountain,specifically comparing the ventilation conditions of Yinxian Rock and Huayang Rock.The following conclusions are drawn:(1)The main wind direction at Yinxian Rock aligns with its orientation,which is an easterly wind,while Huayang Rock experiences a westerly wind,deviating from its southwestern entrance;(2)Huayang Rock has significantly lower wind speeds compared to Yinxian Rock,with minimal airflow;(3)The surrounding environment of Huayang Rock features steep terrain,dense tree cover,and the presence of railings and other structures that impede wind entry into the cave,whereas Yinxian Rock is surrounded by fewer trees and has a flat terrain;(4)In terms of cave morphology,Yinxian Rock is completely open on the east side,while Huayang Rock's opening accounts for only half of its area and is not directly aligned with the rock temple.In summary,Huayang Rock's ventilation environment is inferior to that of Yinxian Rock,leading to more severe pathologies.It is inferred that Huayang Rock's preservation issues are closely related to its poor ventilation environment.Therefore,improving its ventilation conditions is crucial for preventive conservation.Using environmental simulation,this study compares the ventilation conditions of Huayang Rock under different wind directions and speeds,identifies the two most ideal scenarios,and proposes several feasible solutions.展开更多
Background:Mechanical ventilation(MV)provides life support for patients with severe respiratory distress but can simultaneously cause ventilator-induced lung injury(VILI).However,due to a poor understanding of its mec...Background:Mechanical ventilation(MV)provides life support for patients with severe respiratory distress but can simultaneously cause ventilator-induced lung injury(VILI).However,due to a poor understanding of its mechanism,there is still a lack of effective remedies for the often-deadly VILI.Recent studies indicate that the stretch associated with MV can enhance the secretion of extracellular vesicles(EVs)and induce endoplasmic reticulum(ER)stress in airway smoothmuscle cells(ASMCs),both of which can contribute to VILI.But whetherMVassociated stretch enhances the secretion of EVs via ER stress in ASMCs as an underlying mechanism of VILI remains unknown.Methods:In this study,we exposed cultured human ASMCs to stretch(13%strain)and mouse models to MV at tidal volume(18 mL/kg).Subsequently,the amount of secreted EVs in the culture medium of ASMCs and the bronchoalveolar lavage fluid(BALF)of mousemodels was quantitatively evaluated by ultracentrifugation,transmission electron microscopy,Western blot,flow cytometry,and nanoparticle tracking analysis.The cultured ASMCs and the lung tissues of mouse models were assessed for expression of biomarkers of EVs(cluster of differentiation antigen 63,CD63),ER stress(heat shock protein family A member 5,HSPA5),and EVs regulating molecule Rab27a by immunofluorescence microscopy,immunohistochemistry(IHC)and enzyme-linked immunosorbent assay(ELISA),respectively.MicroRNAs(miRNAs)in EVs from ASMCs were measured with miRNA whole genome sequencing(miRNA-Seq).Results:We found that stretch enhanced EV secretion from cultured ASMCs.In addition,the cultured ASMCs and the mouse models were either or not pretreated with ER stress inhibitor(tauroursodeoxycholic acid,TUDCA)/EV secretion inhibitor(GW4869)prior to stretch or MV.We found that MV-associated stretch enhanced the expression of CD63,HSPA5,and Rab27a in cultured ASMCs and BALF/lung tissues of mousemodels,which could all be attenuated with TUDCA/GW4869 pretreatment.miRNA-Seq data show that differentially expressed miRNAs in EVsmainlymodulate gene transcription.Furthermore,the EVs fromcultured ASMCs under stretch tended to enhance detachment and expression of inflammatory cytokines,i.e.,transforming growth factor-β1(TGF-β1),interleukin-10(IL-10)in cultured airway epithelial cells.The expression of TGF-β1 and IL-10 in BALF of the mouse models also increased in response to MV,which was attenuated together with partial improvement of lung injury by pretreatment with TUDCA,GW4869/Rab27a siRNAs.Conclusion:Taken together,our data indicate thatMV-associated stretch can enhance the secretion of EVs from ASMCs via ER stress signaling to mediate airway inflammation and VILI,which provides new insight for further exploring EVs for the diagnosis and treatment of VILI.展开更多
文摘BACKGROUND Acute respiratory distress syndrome(ARDS)is a critical condition characterized by acute hypoxemia,non-cardiogenic pulmonary edema,and decreased lung compliance.The Berlin definition,updated in 2012,classifies ARDS severity based on the partial pressure of arterial oxygen/fractional inspired oxygen fraction ratio.Despite various treatment strategies,ARDS remains a significant public health concern with high mortality rates.AIM To evaluate the implications of driving pressure(DP)in ARDS management and its potential as a protective lung strategy.METHODS We conducted a systematic review using databases including EbscoHost,MEDLINE,CINAHL,PubMed,and Google Scholar.The search was limited to articles published between January 2015 and September 2024.Twenty-three peer-reviewed articles were selected based on inclusion criteria focusing on adult ARDS patients undergoing mechanical ventilation and DP strategies.The literature review was conducted and reported according to PRISMA 2020 guidelines.RESULTS DP,the difference between plateau pressure and positive end-expiratory pressure,is crucial in ARDS management.Studies indicate that lower DP levels are significantly associated with improved survival rates in ARDS patients.DP is a better predictor of mortality than tidal volume or positive end-expiratory pressure alone.Adjusting DP by optimizing lung compliance and minimizing overdistension and collapse can reduce ventilator-induced lung injury.CONCLUSION DP is a valuable parameter in ARDS management,offering a more precise measure of lung stress and strain than traditional metrics.Implementing DP as a threshold for safety can enhance protective ventilation strategies,po-tentially reducing mortality in ARDS patients.Further research is needed to refine DP measurement techniques and validate its clinical application in diverse patient populations.
文摘BACKGROUND Many studies have revealed a link between non-alcoholic fatty liver disease(NA-FLD)and coronavirus disease 2019(COVID-19),making understanding the relationship between these two conditions an absolute requirement.AIM To provide a qualitative synthesis on the currently present data evaluating COVID-19 and NAFLD.METHODS This systematic review was conducted in accordance with the guidelines pro-vided by preferred reporting items for systematic reviews and meta-analyses and the questionnaire utilized the population,intervention,comparison,and outcome framework.The search strategy was run on three separate databases,PubMed/MEDLINE,Scopus,and Cochrane Central,which were systematically searched from inception until March 2024 to select all relevant studies.In addition,ClinicalTrials.gov,Medrxiv.org,and Google Scholar were searched to identify grey literature.RESULTS After retrieval of 11 studies,a total of 39282 patients data were pooled.Mortality was found in 11.5%and 9.4%of people in NAFLD and non-NAFLD groups.In all,23.2%of NAFLD patients and 22%of non-NAFLD admissions diagnosed with COVID-19 were admitted to the intensive care unit,with days of stay varying.Ventilatory support ranged from 5%to 40.5%in the NAFLD cohort and from 3.1%to 20%in the non-NAFLD cohort.The incidence of acute liver injury showed significance.Clinical improvement on days 7 and 14 between the two classifications was significant.Hospitalization stay ranged from 9.6 days to 18.8 days and 7.3 days to 16.4 days in the aforementioned cohorts respectively,with 73.3%and 76.3%of patients being discharged.Readmission rates varied.CONCLUSION Clinical outcomes except mortality consistently showed a worsening trend in patients with NAFLD and concomitant COVID-19.Further research in conducting prospective longitudinal studies is essential for a more powerful conclusion.
文摘This paper is based on the rainwater collection project in the retrofit of the Dongyi teaching block in Zhejiang University Xixi Campus.The analysis incorporates the local meteorological data, recycling water utilization, and precipitation adjustment.The rainwater collection system in this program also adds the condensation water from the heating, ventilation and air conditioning （ HVAC） system and the concentration from the reverse-osmosis system used for watering greens and supplying waterscapes.By calculating, the quantity of the HVAC condensation water in summer is 3.48 m3/d, and the quantity of the reverse-osmosis concentrated water is 198 to 396 L/d.This method solves the water shortage caused by high evaporation in summer and low precipitation in winter.Supported by empirical monitoring data, the proposed method significantly increases the economic efficiency of the system during the summer period.
文摘https://www.sciencedirect.com/journal/energy-and-buildings/vol/342/suppl/C Volume 342,1 September 2025[OA](1)Experimental validation of neural network-based prediction of natural ventilation bulk airflow rate by Jo ao Carlos Sim oes,Guilherme Carrilho da Graca,Article115871Abstract:To fully exploit natural ventilation(NV)as an energysaving strategy in mixed-mode buildings,accurate real-time prediction of NV airflow rates is essential.Current approaches for NV airflow rates prediction often rely heavily on expertise knowledge and computationally demanding methods such as Computational Fluid Dynamics(CFD)as well as expensive and complex direct airflow measurements.
文摘BACKGROUND A major cause of mortality in the coronavirus disease 2019(COVID-19)pandemic was acute respiratory distress syndrome(ARDS).Currently,moderate to severe ARDS induced by COVID-19(COVID ARDS)and other viral and non-viral etiologies are treated by traditional ARDS protocols that recommend 12-16 hours of prone position ventilation(PPV)with neuromuscular blocking agents(NMBA)and a trial of inhaled vasodilators(IVd)if oxygenation does not improve.However,debate on the efficacy of adjuncts to PPV and low tidal volume ventilation persists and evidence about the benefits of IVd/NMBA in COVID ARDS is sparse.In our multi-center retrospective review,we evaluated the impact of PPV,IVd,and NMBA on outcomes and lung mechanics in COVID ARDS patients with moderate to severe ARDS.AIM To evaluate the impact of PPV used alone or in combination with pulmonary IVd and/or NMBA in mechanically ventilated patients with moderate to severe ARDS during the COVID-19 pandemic.METHODS A retrospective study at two tertiary academic medical centers compared outcomes between COVID ARDS patients receiving PPV and patients in the supine position.PPV patients were divided based on concurrent use of ARDS adjunct therapies resulting in four subgroups:(1)PPV alone;(2)PPV and IVd;(3)PPV and NMBA;and(4)PPV,IVd,and NMBA.Primary outcomes were hospital and intensive care unit(ICU)length of stay(LOS),mortality,and venovenous extracorporeal membrane oxygenation(VV-ECMO)status.Secondary outcomes included changes in lung mechanics at 24-hour intervals for 7 days.RESULTS Total 114 patients were included in this study.Baseline respiratory parameters and Sequential Organ Failure Assessment scores were significantly worse in the PPV group.ICU LOS and LOS were significantly longer for patients who were proned,but no mortality benefit or difference in VV-ECMO status was found.Among the subgroups,no difference in primary outcomes were found.In the secondary analysis,PPV was associated with a significant improvement in arterial oxygen partial pressure(PaO_(2))/fractional inspired oxygen(FiO_(2))(P/F)ratio from day 1 to day 4(P<0.05)and higher driving pressures day 5 to day 7(P<0.05).The combination of PPV and IVd together resulted in improvements in P/F ratio from day 1 to day 7 and plateau pressure on day 4 and day 6(P<0.05).PPV with NMBA was not associated with improvements in any of the secondary outcomes.The use of all three rescue therapies together resulted in improvements in lung compliance on day 2(P<0.05)but no other improvements.CONCLUSION In mechanically ventilated patients diagnosed with moderate to severe COVID ARDS,PPV and PPV with the addition of IVd produced a significant and sustained increase in P/F ratio.The combination of PPV,IVd and NMBA improved compliance however this did not reach significance.Mortality and LOS did not improve with adjunct therapies.Further research is warranted to determine the efficacy of these therapies alone and in combination in the treatment of COVID ARDS.
文摘BACKGROUND:In this study,we aimed to evaluate the impact of mechanical ventilator(MV)utilizaton during cardiopulmonary resuscitation(CPR)on out-of-hospital cardiac arrest(OHCA)patient clinical outcomes in the emergency department.METHODS:This single-centered,retrospective,case-control study analyzed electronic medical records.Patients aged>18 years with non-traumatic OHCA who were treated at an emergency medical center between January 2019 and December 2023 were included.These patients were accessed according to the ventilatory method used:MV ventilation(volume control,tidal volume 6-8 mL/kg,frequency 10 beat per minute,inspiratory time 1 s)and manual resuscitator bag valve(BV)ventilation.The primary outcome was the return of spontaneous circulation(ROSC).After 1:1 propensity score matching,the clinical outcomes were analyzed.RESULTS:A total of 649 patients were enrolled in this study.Before matching,the clinical outcomes and pneumothorax incidence did not differ between the MV and BV groups.After 1:1 matching between the two groups using propensity scores,522 patients(261 MV and 261 BV)were analyzed.Propensity score matching yielded an adequate balance(standardized mean difference<0.10)for all covariates.The estimated odds ratio(OR)for ROSC was 1.23(95%confidence interval[CI]:0.85-1.77;P=0.267),for survival at hospital admission was 1.02(95%CI:0.68-1.53;P=0.918),for survival at hospital discharge was 2.31(95%CI:1.10-5.20;P=0.033),and for good neurologic outcome was 2.56(95%CI:0.84-9.43;P=0.116).CONCLUSION:In patients with OHCA admitted to the emergency department,MV ventilation during CPR showed clinical outcomes similar to those of BV ventilation in most measures.However,survival at hospital discharge was significantly higher in the MV group,suggesting potential benefits of MV use in selected patients.
文摘Prediction of weaning success from invasive mechanical ventilation remains a challenge in everyday clinical practice.Several prediction scores have been developed to guide success during spontaneous breathing trials to help with weaning decisions.These scores aim to provide a structured framework to support clinical judgment.However,their effectiveness varies across patient populations,and their predictive accuracy remains inconsistent.In this review,we aim to identify the strengths and limitations of commonly used clinical prediction tools in assessing readiness for ventilator liberation.While scores such as the Rapid Shallow Breathing Index and the Integrative Weaning Index are widely adopted,their sensitivity and specificity often fall short in complex clinical settings.Factors such as underlying disease pathophysiology,patient characteristics,and clinician subjectivity impact score performance and reliability.Moreover,disparities in validation across diverse populations limit generalizability.With growing interest in artificial intelligence(AI)and machine learning,there is potential for enhanced prediction models that integrate multidimensional data and adapt to individual patient profiles.However,current AI approaches face challenges related to interpretability,bias,and ethical implementation.This paper underscores the need for more robust,individualized,and transparent prediction systems and advocates for careful integration of emerging technologies into clinical workflows to optimize weaning success and patient outcomes.
文摘BACKGROUND Gastroesophageal reflux disease(GERD)is common among neonates,particularly those requiring mechanical ventilation.Pepsin,a reliable marker of gastric aspi-ration,may help detect GER episodes in ventilated neonates and assess associated clinical outcomes.AIM To determine the incidence of GERD,associated risk factors,and morbidities among full-term mechanically ventilated neonates by detecting pepsin in endo-tracheal aspirates(ETA).METHODS This study included 97 full-term neonates admitted to the neonatal intensive care unit at Cairo University Hospitals from April 2023 to March 2024.ETA samples were collected at three intervals:Immediately post-intubation(Sample A),48 hours after intubation(Sample B),and just before extubation(Sample C).Pepsin concentration was measured using enzyme-linked immunosorbent assay.Clinical data,including hospital stay duration and feeding parameters,were correlated with pepsin levels.RESULTS Pepsin was detected in 76(78.4%)of Sample A,78(81.3%)of Sample B,and 47(68.1%)of Sample C.A significant positive correlation was found between pepsin levels and FiO_(2) in Sample B(r=0.203,P=0.047).Prolonged hospital stay was also associated with pepsin detection in Samples B and C(P<0.05).A negative correlation was observed between feeding amount and pepsin levels across all samples(P<0.05).CONCLUSION The incidence of GERD in full-term mechanically ventilated neonates is high,correlating with pepsin levels,FiO_(2),feeding intolerance,and hospital stay,highlighting the importance of early detection.
文摘BACKGROUND Lung ultrasonography is being increasingly used in mechanically ventilated patients to evaluate the lung aeration during incremental positive end expiratory pressure(PEEP)adjustments and to evaluate the weaning process from mechanical ventilation.The effects of PEEP may vary across different lung pathologies and may not consistently correlate with changes in lung aeration as assessed by lung ultrasound scores(LUSs).AIM To assess the role of lung ultrasonography in evaluating lung aeration during the application of PEEP in mechanically ventilated patients with various lung pathologies.METHODS An observational study was conducted over 18 months in a tertiary care hospital.Patients of both genders,aged between 18-75 years,who had been admitted to the intensive care unit,and required mechanical ventilation,were studied.A standard ventilatory strategy was used and incremental levels of PEEP[5,10,and 15 cm water(H_(2)O)]were applied.Baseline characteristics,including oxygen saturation(SpO2),LUS,mean arterial pressure(MAP),heart rate(HR),and their changes with incremental PEEP levels,were recorded and analyzed.RESULTS In this study,45.9%of patients required a PEEP of 5 cm H_(2)O to achieve the endpoint of lung aeration(LUS of 0).In addition,86.5% and 13.5% of patients reached the endpoint of lung aeration at PEEP levels of 10 and 15 cm H_(2)O,respectively.The proportion of patients with higher lung scores decreased significantly with increasing PEEP levels(P<0.001 for 5 and 10 cm H_(2)O and P=0.032 for 15 cm H_(2)O).SpO2 increased significantly with higher PEEP levels(P<0.001),confirming the effectiveness of PEEP in improving oxygenation.The results also revealed a significant increase in HR and a decrease in MAP following the application of higher PEEP levels.CONCLUSION Increasing PEEP levels in mechanically ventilated patients improves lung aeration,which can be effectively assessed using bedside lung ultrasonography.
文摘Mechanical ventilation is a specialized oxygen therapy and life support technology with significant importance for critically ill patients. In fact, 40%–66% of patients in the intensive care unit(ICU) require mechanical ventilation.^([1,2]) However, the mechanical ventilation can lead to ventilatorassociated lung injury(VALI),^([3]) ultimately resulting in difficulties in weaning from mechanical ventilation,prolonged hospital stays, and even increased mortality.
文摘The longitudinal ventilation strategy is commonly used for road tunnels in urban environment in Sweden.This is partly due to how tunnels in urban environment was planned and designed before the EU Directive[1](2004/54/EC)came in place.Even in new tunnels both to practical and economic reasons the use of longitudinal ventilation has been an outspoken demand from the Swedish road authority,SRA.Swedish law[2]requires that a risk analysis is carried out to demonstrate that an acceptable level of risk is achieved in the tunnels with longitudinal ventilation if there is a risk of queues.Otherwise transverse or semi-transverse ventilation strategy shall be used.During recent development,or a late awakening,it is clear that dense populated areas in Sweden will experience queues.This threatens the foundation of the Swedish modern tunnel safety concept which calls for enhancement.This paper presents the risk-reducing effect of three alternative strategies,enhancements package,focusing on evacuation safety for road users.It is a combination of traffic management,fixed firefighting systems,reduced distance between escape routes and regulation of traffic with dangerous goods.In addition,it provides a comprehensive review of safety system details,combined with a longitudinal ventilation concept.
文摘With different structural forms of ventilation pipes have various attenuation effects on incident shock waves while meeting ventilation requirements.The attenuation mechanism and the propagation law of shock waves in ventilation pipes of different structures are investigated by experiments and numerical simulations.Furthermore,for the same structure,the effects of peak pressure and positive pressure time on the attenuation rate are discussed.It is found that the attenuation rate increases with the incident shock wave pressure,and the shock wave attenuation rate tends to reach its limiting value k for the same structure and reasonably short positive pressure time.Under the same conditions,the attenuation rate is calculated using the pressure of the shock wave as follows:diffusion chamber pipe,branch pipe and selfconsumption pipe;the attenuation rate per unit volume is calculated as follows:self-consumption pipe,branch pipe and diffusion chamber pipe.In addition,an easy method is provided to calculate the attenuation rate of the shock wave in single and multi-stage ventilation pipes.Corresponding parameters are provided for various structures,and the margin of error between the formulae and experimental results is within 10%,which is significant for engineering applications.
基金Sichuan Provincial Medical Scientific Research Project(Project No.:s19085)。
文摘Objective:To explore the role of lung ultrasound combined with multi-organ evaluation in assessing the risk of weaning from mechanical ventilation(MV)in severe patients.Methods:A retrospective analysis was conducted on 60 severe patients admitted to the hospital from December 2022 to December 2024,all of whom underwent MV treatment.Based on weaning status,thirty-eight patients were successfully weaned(success group),and 22 patients failed weaning(failure group).All patients underwent lung ultrasound and multi-organ evaluation.The parameter differences between the two groups were compared,risk factors for weaning risk were evaluated,and a receiver operating characteristic curve(ROC)was drawn to assess the predictive value of lung ultrasound combined with multi-organ evaluation for weaning risk.Results:The lung ultrasound score(LUS)of the success group was lower than that of the failure group,the left ventricular ejection fraction(LVEF)was higher than that of the failure group,and the diaphragmatic excursion(DE)and diaphragmatic thickening fraction(DTF)were higher than those of the failure group(P<0.05).Multifactor analysis showed that LUS was a risk factor for weaning risk,while LVEF,DE,and DTF were protective factors(P<0.05).The ROC showed that the area under the curve(AUC)of a single parameter for weaning risk was smaller than that of the combined parameters(P<0.05).Conclusion:Lung ultrasound combined with multi-organ evaluation can predict the weaning risk of severe patients undergoing MV treatment,and the diagnostic efficiency of multiple parameters combined evaluation is higher.
基金Funding Statement:This research was conducted as part of the Tech4You Project“Technologies for climate change adaptation and quality of life improvement”,n.ECS0000009,CUP H23C22000370006,Italian PNRR,Mission 4,Component 2,Investment 1.5 funded by the European Union-NextGenerationEU.
文摘Indoor air quality(IAQ)is often overlooked,yet a poorly maintained environment can lead to significant health issues and reduced concentration and productivity in work or educational settings.This study presents an innovative control system for mechanical ventilation specifically designed for university classrooms,with the dual goal of enhancing IAQ and increasing energy efficiency.Two classrooms with distinct construction characteristics were analyzed:one with exterior walls and windows,and the other completely underground.For each classroom,a model was developed using DesignBuilder software,which was calibrated with experimental data regarding CO_(2) concentration,temperature,and relative humidity levels.The proposed ventilation system operates based on CO_(2) concentration,relative humidity,and potential for free heating and cooling.In addition,the analysis was conducted for other locations,demonstrating consistent energy savings across different climates and environments,always showing an annual reduction in energy consumption.Results demonstrate that mechanical ventilation,when integrated with heat recovery and free cooling strategies,significantly reduces energy consumption by up to 25%,while also maintaining optimal CO_(2) levels to enhance comfort and air quality.These findings emphasize the essential need for well-designed mechanical ventilation systems to ensure both psychophysical well-being and IAQ in enclosed spaces,particularly in environments intended for extended occupancy,such as classrooms.Furthermore,this approach has broad applicability,as it could be adapted to various building types,thereby contributing to sustainable energy management practices and promoting healthier indoor spaces.This study serves as a model for future designs aiming to balance energy efficiency with indoor air quality,especially relevant in the post-COVID era,where the importance of indoor air quality has become more widely recognized.
基金Supported by Non-profit Joint Stock Company“S.D.Asfendiyarov Kazakh National Medical University”,Almaty,Kazakhstan。
文摘BACKGROUND For over half a century,the administration of maternal corticosteroids before anticipated preterm birth has been regarded as a cornerstone intervention for enhancing neonatal outcomes,particularly in preventing respiratory distress syndrome.Ongoing research on antenatal corticosteroids(ACS)is continuously refining the evidence regarding their efficacy and potential side effects,which may alter the application of this treatment.Recent findings indicate that in resource-limited settings,the effectiveness of ACS is contingent upon meeting specific conditions,including providing adequate medical support for preterm newborns.Future studies are expected to concentrate on developing evidence-based strategies to safely enhance ACS utilization in low-and middle-income countries.AIM To analyze the clinical effectiveness of antenatal corticosteroids in improving outcomes for preterm newborns in a tertiary care hospital setting in Kazakhstan,following current World Health Organization guidelines.METHODS This study employs a comparative retrospective cohort design to analyze single-center clinical data collected from January 2022 to February 2024.A total of 152 medical records of preterm newborns with gestational ages between 24 and 34 weeks were reviewed,focusing on the completeness of the ACS received.Quantitative variables are presented as means with standard deviations,while frequency analysis of qualitative indicators was performed using Pearson'sχ^(2) test(χ^(2))and Fisher's exact test.If statistical significance was identified,pairwise comparisons between the three observation groups were conducted using the Bonferroni correction.RESULTS The obtained data indicate that the complete implementation of antenatal steroid prophylaxis(ASP)improves neonatal outcomes,particularly by reducing the frequency of birth asphyxia(P=0.002),the need for primary resuscitation(P=0.002),the use of nasal continuous positive airway pressure(P=0.022),and the need for surfactant replacement therapy(P=0.038)compared to groups with incomplete or no ASP.Furthermore,complete ASP contributed to a decrease in morbidity among preterm newborns(e.g.,respiratory distress syndrome,intrauterine pneumonia,cerebral ischemia,bronchopulmonary dysplasia,etc.),improved Apgar scores,and reduced the need for re-intubation and the frequency of mechanical ventilation.However,it was associated with an increased incidence of uterine atony in postpartum women(P=0.0095).CONCLUSION In a tertiary hospital setting,the implementation of ACS therapy for pregnancies between 24 and 34 weeks of gestation at high risk for preterm birth significantly reduces the incidence of neonatal complications and related interventions.This,in turn,contributes to better outcomes for this cohort of children.However,the impact of ACS on maternal outcomes requires further thorough investigation.
基金Project(12372049)supported by the National Natural Science Foundation of ChinaProject(2682023ZTPY036)supported by the Fundamental Research Funds for the Central Universities,ChinaProject(2023TPL-T06)supported by the Independent Project of State Key Laboratory of Rail Transit Vehicle System,China。
文摘Ventilation systems are critical for improving the cabin environment in high-speed trains,and their interest has increased significantly.However,whether air supply non-verticality deteriorates the cabin air environment,and the flow mechanism behind it and the degree of deterioration are not known.This study first analyzes the interaction between deflection angle and cabin flow field characteristics and ventilation performance.The results revealed that the interior temperature and pollutant concentration decreased slightly with increasing deflection angle,but resulted in significant deterioration of thermal comfort and air quality.This is evidenced by an increase in both draught rate and non-uniformity coefficient,an increase in the number of measurement points that do not satisfy the micro-wind speed and temperature difference requirements by about 5% and 15%,respectively,and an increase in longitudinal penetration of pollutants by a factor of about 5 and the appearance of locking regions at the ends of cabin.The results also show that changing the deflection pattern only affects the region of deterioration and does not essentially improve this deterioration.This study can provide reference and help for the ventilation design of high-speed trains.
文摘Heat Recovery Ventilators(HRVs)are essential for improving indoor air quality(IAQ)and reducing energy consumption in residential buildings situated in cold climates.This study considers the efficiency and performance optimization of HRVs under cold climatic conditions,where conventional ventilation systems increase heat loss.A comprehensive numerical model was developed using COMSOL Multiphysics,integrating fluid dynamics,heat transfer,and solid mechanics to evaluate the thermal efficiency and structural integrity of an HRV system.The methodology employed a detailed geometry with tetrahedral elements,temperature-dependent material properties,and coupled governing equations solved under Tehran-specific boundary conditions.A multi-objective optimization was implemented in the framework of the Nelder-Mead simplex algorithm,targeting the maximization of the average outlet temperature and minimization of the maximum von Mises thermal stress,with inlet flow velocity as the design variable(range:0.5–1.2m/s).Results indicate an optimal velocity of 0.51563 m/s,achieving an average outlet temperature of 289.44 K and maximum von Mises stress of 221 MPa,validated through mesh independence and detailed contour analyses of temperature,velocity,and stress distributions.
基金support by Technology R&D Program of China State Railway Group Co.,Ltd(Grant number N2022J013)the Hunan Provincial Innovation Foundation for Postgraduate(Grant number CX20220279)+1 种基金the Fundamental Research Funds for the Central Universities of Central South University(Grant number 2022ZZTS0193)China Scholarship Council(202106370112)。
文摘During the train meeting events,train equipment compartments are exposed to the worst pressure changes,potentially affecting the ventilation performance of equipment,particularly for electrical facilities equipped with independent air ducts.In this paper,a two-step method is used for numerical computation:(1)obtaining the temporal and spatial transient node data of the flow field sections during the train-passing simulation and(2)using the data as the input data for the equipment compartment simulation.In addition,this paper also compares the difference in equipment ventilation between the single-train and trainpassing scenarios in real vehicle tests.The results indicate that the primary factors influencing ventilation effectiveness are the aerodynamic compression and deceleration of airflow induced by the other train's nose,as well as the instability of the external flow field in the wake of the other train.During train crossing,the air is forced into the air duct,with a maximum ratio of the airflow in-duct to the airflow out-duct reaching 3.2.The average mass flow falls below the rated mass flow for the converter.Compared to the rated air volume of converter,the maximum suppression rates obtained from testing and simulation are-24.5%and-16.8%,respectively.Compared to the single-train operation,the maximum suppression rates obtained from testing and simulation are-15%and-18%,respectively.These findings provide valuable insights into the design and operation of high-speed trains.
基金Supported by the National Natural Science Foundation of China(Grant No.52278042)for the research on"Architectural issue mechanisms and defense of architectural heritage under harsh environments-Taking the rock temples of Wudang Mountain as an example."。
文摘The preservation condition of historical buildings is closely related to their ventilation environment.This study focuses on the rock temples in Wudang Mountain,specifically comparing the ventilation conditions of Yinxian Rock and Huayang Rock.The following conclusions are drawn:(1)The main wind direction at Yinxian Rock aligns with its orientation,which is an easterly wind,while Huayang Rock experiences a westerly wind,deviating from its southwestern entrance;(2)Huayang Rock has significantly lower wind speeds compared to Yinxian Rock,with minimal airflow;(3)The surrounding environment of Huayang Rock features steep terrain,dense tree cover,and the presence of railings and other structures that impede wind entry into the cave,whereas Yinxian Rock is surrounded by fewer trees and has a flat terrain;(4)In terms of cave morphology,Yinxian Rock is completely open on the east side,while Huayang Rock's opening accounts for only half of its area and is not directly aligned with the rock temple.In summary,Huayang Rock's ventilation environment is inferior to that of Yinxian Rock,leading to more severe pathologies.It is inferred that Huayang Rock's preservation issues are closely related to its poor ventilation environment.Therefore,improving its ventilation conditions is crucial for preventive conservation.Using environmental simulation,this study compares the ventilation conditions of Huayang Rock under different wind directions and speeds,identifies the two most ideal scenarios,and proposes several feasible solutions.
基金funded by the Natural Science Foundation of China(NSFC),Grants No.12072048 to M.L.,12272063,and 11532003 to L.D.partially supported by the Science and Technology Innovation Leading Plan of High-Tech Industry in Hunan Province,China,Grant No.2020SK2018 to L.D.
文摘Background:Mechanical ventilation(MV)provides life support for patients with severe respiratory distress but can simultaneously cause ventilator-induced lung injury(VILI).However,due to a poor understanding of its mechanism,there is still a lack of effective remedies for the often-deadly VILI.Recent studies indicate that the stretch associated with MV can enhance the secretion of extracellular vesicles(EVs)and induce endoplasmic reticulum(ER)stress in airway smoothmuscle cells(ASMCs),both of which can contribute to VILI.But whetherMVassociated stretch enhances the secretion of EVs via ER stress in ASMCs as an underlying mechanism of VILI remains unknown.Methods:In this study,we exposed cultured human ASMCs to stretch(13%strain)and mouse models to MV at tidal volume(18 mL/kg).Subsequently,the amount of secreted EVs in the culture medium of ASMCs and the bronchoalveolar lavage fluid(BALF)of mousemodels was quantitatively evaluated by ultracentrifugation,transmission electron microscopy,Western blot,flow cytometry,and nanoparticle tracking analysis.The cultured ASMCs and the lung tissues of mouse models were assessed for expression of biomarkers of EVs(cluster of differentiation antigen 63,CD63),ER stress(heat shock protein family A member 5,HSPA5),and EVs regulating molecule Rab27a by immunofluorescence microscopy,immunohistochemistry(IHC)and enzyme-linked immunosorbent assay(ELISA),respectively.MicroRNAs(miRNAs)in EVs from ASMCs were measured with miRNA whole genome sequencing(miRNA-Seq).Results:We found that stretch enhanced EV secretion from cultured ASMCs.In addition,the cultured ASMCs and the mouse models were either or not pretreated with ER stress inhibitor(tauroursodeoxycholic acid,TUDCA)/EV secretion inhibitor(GW4869)prior to stretch or MV.We found that MV-associated stretch enhanced the expression of CD63,HSPA5,and Rab27a in cultured ASMCs and BALF/lung tissues of mousemodels,which could all be attenuated with TUDCA/GW4869 pretreatment.miRNA-Seq data show that differentially expressed miRNAs in EVsmainlymodulate gene transcription.Furthermore,the EVs fromcultured ASMCs under stretch tended to enhance detachment and expression of inflammatory cytokines,i.e.,transforming growth factor-β1(TGF-β1),interleukin-10(IL-10)in cultured airway epithelial cells.The expression of TGF-β1 and IL-10 in BALF of the mouse models also increased in response to MV,which was attenuated together with partial improvement of lung injury by pretreatment with TUDCA,GW4869/Rab27a siRNAs.Conclusion:Taken together,our data indicate thatMV-associated stretch can enhance the secretion of EVs from ASMCs via ER stress signaling to mediate airway inflammation and VILI,which provides new insight for further exploring EVs for the diagnosis and treatment of VILI.
