Development of a New Method for Evaluating Heat-and-Moisture Exchanger Performance.

BACKGROUND: A model system described in International Organization for Standardization 9360 is the standard method for estimating the humidifying performance of heat-and-moisture exchangers (HMEs). However, there are no reliable bedside methods for evaluating the ongoing humidification performance of HMEs. Therefore, this study aimed to develop 2 clinically applicable methods for estimating the ongoing humidifying performance of HMEs and to evaluate their reliability in a model system. METHODS: Physiologically expired gas was simulated using a heated humidifier, and ventilation was delivered using a ventilator with constant flow through 3 different types of HMEs. Relative humidity (RH) was measured using a capacitive-type moisture sensor. Water content lost during expiration was calculated by integrating absolute humidity (AH), instantaneous gas flow measured at the expiratory outlet of the ventilator, and time. We also calculated the water content released and captured by the HMEs during tidal ventilation by integrating the difference in AH across the HMEs, instantaneous gas flow, and time. RESULTS: We found that the RH, temperature, and AH were almost constant on the expiratory outlet of the ventilator but rapidly varied near the HMEs. The water content lost by the 3 HMEs was associated with the manufacturer-reported values and inversely correlated with the calculated values of the water content exchanged by the HMEs. The water content released and captured by HMEs was closely correlated with the difference in HME weight measured at the end of inspiration and expiration; however, the water content captured by HMEs seemed to be overestimated. CONCLUSIONS: Our results demonstrated that our system was able to detect the differences in the performance of 3 models of HMEs and suggest that our method for calculating water loss is reliable for estimating the water retention performance of HMEs during mechanical ventilation, even in the presence of a constant flow.

Design of easily swallowable xerogel pill with enough physical strength through hardening-process under heating and humidification.

The xerogel pill has been developed as a novel dosage form with dose-adjusting and swallow-assisting functions by using drop freeze-drying (DFD) technique. It was double-structured small sphere composed of an inner drug core and an outer dried-gel layer, however, had problem of insufficient physical strength. In this study, it was attempted to use dextrin (DEX), one of oligosaccharides, to strengthen the xerogel pill. DEX was co-dissolved in the dropping fluid in the DFD process and co-loaded in the conventional pill, which was mainly composed of mannitol (MNT) as a filler, to prepare the rigid body. DEX-loaded pill could be successfully prepared with high recovery (>90 %) by optimizing the ratio of DEX and MNT. Further, the representative pills with and without DEX (P-DEX and P-MNT, respectively) were hardening-processed under humidification. The physical strength of P-DEX pill was significantly increased when humidified under severe condition, resulting in enough hardness (>5N) and friability (<1.0 %). Processed P-DEX was found to have dense structure covered with a thick outer shell, which would be formed by interparticle bridge of DEX. It was also found that processed P-DEX pill suppressed initial drug dissolution significantly and exhibited sustained dissolution behavior, suggesting the potential function of bitter taste masking. Processed P-DEX pill had excellent sliding behavior with low friction forces as a result of lubricant effect of xanthan gum (XG) surrounding the pills. Furthermore, the sliding test also suggested that processed P-DEX pill had hard candy-like texture, in contrast unprocessed P-DEX pill had orally disintegrating (OD) tablet-like texture. Various xerogel pills with such different swallowing texture would have a potential to accommodate the children's preferences when taking medication.

Humidification during Invasive and Non-Invasive Ventilation: A Starting Tool Kit for Correct Setting.

The humidification process of medical gases plays a crucial role in both invasive and non-invasive ventilation, aiming to mitigate the complications arising from bronchial dryness. While passive humidification systems (HME) and active humidification systems are prevalent in routine clinical practice, there is a pressing need for further evaluation of their significance. Additionally, there is often an incomplete understanding of the operational mechanisms of these devices. The current review explores the historical evolution of gas conditioning in clinical practice, from early prototypes to contemporary active and passive humidification systems. It also discusses the physiological principles underlying humidity regulation and provides practical guidance for optimizing humidification parameters in both invasive and non-invasive ventilation modalities. The aim of this review is to elucidate the intricate interplay between temperature, humidity, and patient comfort, emphasizing the importance of individualized approaches to gas conditioning.

Assessment of high-flow nasal cannula efficacy in humidification of infant airways: A computational fluid dynamics approach.

INTRODUCTION: High-flow nasal cannula therapy has garnered significant interest for managing pathologies affecting infants' airways, particularly for humidifying areas inaccessible to local treatments. This therapy promotes mucosal healing during the postoperative period. However, further data are needed to optimize the use of these devices. In vivo measurement of pediatric airway humidification presents a challenge; thus, this study aimed to investigate the airflow dynamics and humidification effects of high-flow nasal cannulas on an infant's airway using computational fluid dynamics. METHODS: Two detailed models of an infant's upper airway were reconstructed from CT scans, with high-flow nasal cannula devices inserted at the nasal inlets. The airflow was analyzed, and wall humidification was modeled using a film-fluid approach. RESULTS: Air velocities and pressure were very high at the airway inlet but decreased rapidly towards the nasopharynx. Maximum relative humidity-close to 100%-was achieved in the nasopharynx. Fluid film development along the airway was heterogeneous, with condensation primarily occurring in the nasal vestibule and larynx. CONCLUSION: This study provides comprehensive models of airway humidification, which pave the way for future studies to assess the impact of surgical interventions on humidification and drug deposition directly at operative sites, such as the nasopharynx or larynx, in infants.

Effect of Interrupting Heated Humidification on Nebulized Drug Delivery Efficiency, Temperature, and Absolute Humidity During Mechanical Ventilation: A Multi-Lab In Vitro Study.

Introduction: During mechanical ventilation (MV), inspired gases require heat and humidification. However, such conditions may be associated with reduced aerosol delivery efficiency. The practice of turning off heated humidification before nebulization and the impact of nebulization on humidity in a dry ventilator circuit remain topics of debate. This study aimed to assess the effect of turning off heated humidification on inhaled dose and humidity with nebulizer use during adult MV. Methods: A bronchodilator (albuterol) and two antibiotics (Colistimethate sodium and Amikacin sulfate) were nebulized with a vibrating mesh nebulizer placed at the humidifier inlet and in the inspiratory limb at the Y-piece. Additionally, albuterol was nebulized using a jet nebulizer in both placements. Aerosol particle size distribution was determined through a cascade impactor. Absolute humidity (AH) and temperature of inspired gases were determined with anemometer/hygrometers before, during, and after nebulization, before, during, and up to 60 minutes after interrupting active humidification. Aerosol collected on a filter distal to the endotracheal tube and on impactor stages were eluted and assayed by spectrophotometry. Results: The inhaled dose was greater when both nebulizers were placed at the humidifier inlet than the inspiratory limb at the Y-piece. Irrespective of the nebulizer types and placements, the inhaled dose either decreased or showed no significant change after the humidifier was turned off. The aerosol particle size ranged from 1.1 to 2.7 µm. With interruption of active humidification, humidity of inspired gas quickly dropped below recommended levels, and nebulization in dry ventilator circuit produced an AH between 10 and 20 mgH2O/L, lower than the recommended minimum of 30 mgH2O/L. Conclusion: Interrupting active humidification during MV before nebulization did not improve aerosol delivery efficiency for bronchodilator or antibiotics, but did reduce humidity below recommended levels.

Impact of Humidification Modality on Incidence of Endotracheal Tube Occlusion in COVID-19 Patients.

Background: Endotracheal tube (ETT) occlusion is reported at a higher frequency among coronavirus disease-2019 (COVID-19) patients. Prior to the COVID-19 pandemic, literature examining patient and ventilator characteristics, including humidification, as etiologies of ETT occlusion yielded mixed results. Our study examines the relationship of humidification modality with ETT occlusion in COVID-19 patients undergoing invasive mechanical ventilation (IMV). Methods: We conducted a retrospective chart review of COVID-19 patients requiring IMV at a tertiary care center in New York from April 2020 to April 2021. Teleflex Neptune heated wire heated humidification (HH) and hygroscopic Intersurgical FiltaTherm and Sunmed Ballard 1500 heat and moisture exchangers (HME) were used. Episodes of ETT occlusion were recorded. Univariate and multivariable logistic regression models were used to investigate the relationship between humidification modality and the occurrence of ETT occlusion. Findings: A total of 201 eligible patients were identified. Teleflex HH was utilized in 50.2% of the population and the others Intersurgical and Sunmed HME devices. Median age was 62 years and 78.6% of patients had at least one medical comorbidity. Precisely, 24% of patients experienced an ETT occlusion after a median of 12 days. The HME group was younger (58.5 vs 64 years), predominantly male (75% vs 59.4%), and experienced more total ventilator days than the HH group (24 vs 12). Those using the studied HME devices had significantly higher odds of ETT occlusion (OR 4.4, 95% CI 1.8-10.6, P = .0011). Three patients (6.1%) experienced cardiac arrest as a consequence of their occlusion. There were no deaths directly attributed to ETT occlusion. Conclusions: The studied HME devices were significantly associated with higher odds of ETT occlusion in COVID-19 patients requiring invasive mechanical ventilation. These events are not without significant clinical consequences. Prolonged use of under-performing HME devices remains suspect in the occurrence of ETT occlusions.

Diversity Patterns of Eukaryotic Phytoplankton in the Medog Section of the Yarlung Zangbo River.

As one of the important biodiversity conservation areas in China, the ecosystem in the lower reaches of the Yarlung Zangbo River is fragile, and is particularly sensitive to global changes. To reveal the diversity pattern of phytoplankton, the metabarcode sequencing was employed in the Medog section of the lower reaches of the Yarlung Zangbo River during autumn 2019 in present study. The phytoplankton assemblies can be significantly divided into the main stem and the tributaries; there are significant differences in the phytoplankton biomass, alpha and beta diversity between the main stem and the tributaries. While both the main stem and the tributaries are affected by dispersal limitation, the phytoplankton assemblages in the entire lower reaches are primarily influenced by heterogeneous selection. Community dissimilarity and assembly process were significantly correlated with turbidity, electrical conductivity, and nitrogen nutrition. The tributaries were the main source of the increase in phytoplankton diversity in the lower reaches of the Yarlung Zangbo River. Such diversity pattern of phytoplankton in the lower reach may be caused by the special habitat in Medog, that is, the excessive flow velocity, and the significant spatial heterogeneity in physical and chemical factors between stem and tributaries. Based on the results and conclusions obtained in present study, continuous long-term monitoring is essential to assess and quantify the impact of global changes on phytoplankton.

Application of the integrated airway humidification device enhances the humidification effect of the rabbit tracheotomy model.

Long-term mechanical ventilation after tracheotomy is a common treatment in intensive care unit patients. This study investigated the differences among the effects of different wetting states on the airway, lung, and serum inflammatory factors. New Zealand rabbits (n = 36) were selected to construct tracheotomy models and then divided into four groups: Model, Mask, YTH, and Sham groups. Lung tissue dry/wet ratio was used to evaluate the humidification effect; cytokines, including tumor necrosis factor-α, interleukin (IL)-6, IL-8, and IL-10, were used to evaluate the inflammatory response; hematoxylin and eosin staining was used to evaluate the histopathology. Post hoc analysis based on the Dunnett t-test was applied. A self-developed integrated wetting device could increase the utilization of wetting solution, enhance the effect of wetting to protect tissue integrity, and suppress airway inflammation, reducing the expression of pro-inflammatory factors while promoting the expression of anti-inflammatory factor IL-10 to inhibit the inflammatory response, compared to other methods. The integrated humidification device provided a new method for clinical nursing practice, improving clinical efficiency and reducing nursing workload. Further clinical trials are required to test its effectiveness and safety in the clinic.

Experimental assessment of energy tower's performance: evaluation of the impacts of solar radiation, humidity, and chimney's height on the overall efficiency.

Solar energy is one of the most feasible options to produce energy in countries where unexploited desert areas or solar radiation are abundant. An energy tower is an effective system for electrical power generation that can perform more efficiently along with solar radiation. As the primary aim of the present study, effects of different environmental parameters on total efficacy of energy tower were investigated. In this study, the efficiency of the energy tower system is investigated experimentally by an indoor fully adjustable apparatus. In this regard, a comprehensive set of influencing parameters like air velocity, humidity, and temperature and the effects of tower height on the performance of the energy tower are individually assessed. It is demonstrated that there is a direct relationship between an increase in humidity percentage of the surrounding and performance of energy tower, meaning that a 274% increase in humidification rate led to 43% elevation in airflow velocity. The kinetic energy increases in the direction of airflow from top to bottom, and as the height of the tower lengthens, the kinetic energy enhances and subsequently increases the overall efficiency of the tower. An elevation about 2.7% in airflow velocity was seen due to an increase from 180 to 250 cm in chimney height. Although the energy tower performs efficiently in the nighttime, airflow velocity increases averagely about 8% during the daytime and at the peak of the solar radiation, the airflow velocity enhances by 58% compared to nighttime.

Salinity impacts on humidification dehumidification (HDH) desalination systems: review.

The use of humidification-dehumidification water desalination technology has been shown to be a practical means of meeting the demand for freshwater. The aim of this review is to investigate the impact of salinity on HDH techniques that have various benefits in terms of both economics and the environment, including the capacity to operate at low temperatures, utilize sustainable energy sources, the need for low maintenance, and straightforward construction requirements. Also, in this review, it is observed that the HDH system's components are strong and capable of treating severely salinized water. It can treat water in an appropriate way than other desalination technologies. This technology has recently been commercialized to treat highly salinized generated water. However, more research is needed to determine how salinity affects HDH productivity. According to several research investigations, while the specific thermal energy consumption increased considerably and the productivity of water per unit of time decreased significantly as the salt mass percentage grew, the purity of clean water did not suffer. The rejected brine must be reduced by increasing the total water recovery ratio in the HDH system. Through this review, it was found that brine control is becoming increasingly important in the water processing industry. ZLD systems, which aim to recover both freshwater and solid salts, can be a viable replacement for disposal methods. Finally, through this reviewer, it was concluded that HDH desalination systems may operate with extremely saline water while increasing salinity has a significant influence on system performance.

Investigations on a solar humidification dehumidification desalination system equipped with various packing materials and multi-stage bubble column dehumidifier.

This work presents the theoretical and experimental investigation of a solar-powered humidification dehumidification desalination (HDD) system with different humidifier packing materials and a two-stage bubble column dehumidifier (BCD). Naturally available coconut shells (CS) and coconut shells with drilled holes (CSH) on the surface to improve water permeability were used as packing materials in the humidifier, and their performance was compared with that of commercial-type pall ring (PR) and raschig ring (RR) packings. An in-house developed numerical model of the HDD system in conjunction with a flat plate solar water collector was used in this study. Steady-state experimental results showed that CSH packing exhibited the highest volumetric mass transfer coefficient (0.00852 kg/s), resulting in maximum humidifier efficiency (96%) and freshwater yield (2.16 kg/hr), followed by PR (0.00841 kg/s, 94%, and 2.137 kg/hr), CS (0.00831 kg/s, 90%, and 2.127 kg/hr), and RR (0.0081 kg/s, 81%, and 2.087 kg/hr) at feedwater mass flow rate of 1.5 kg/min and humidifier inlet temperature of 75 [Formula: see text]. Furthermore, transient outdoor test results showed that using a two-stage configuration in a BCD increased the daily average effectiveness to 0.93, as against 0.79 for a single-stage BCD. Employing CSH instead of PR and RR packings in the humidifier reduced freshwater costs by 6.2% and 7.6%, respectively.

Significant increase in humidity since 2003 in Qinghai Province, China: evidence from annual and seasonal precipitation.

Recently, extreme climate events have become more frequent under global warming, resulting in increasingly severe disaster losses. Essentially, the variability in precipitation is more uncertain compared to temperature. In this study, monthly precipitation data from 30 stations in Qinghai Province from 1960 to 2020 were selected to investigate the spatial-temporal variations in precipitation via linear tendency estimation, variability, cumulative anomaly, Mann-Kendall test, and spatial interpolation methods. The conclusions are as follows. (1) The annual and four seasons' average precipitation in Qinghai Province showed an increasing trend over the last 61 years, and the enhancement of summer and spring average precipitation contributed more to the annual. (2) There are increasing trends from northwest to southeast in the annual and seasonal mean precipitation, whose distributions are jointly controlled by the East Asian summer monsoon (EASM), the westerlies, and geomorphological features. (3) It is reasonable to conclude that the annual and four seasons' average precipitation has increased significantly since 2003 by integrating the results of variability, cumulative anomaly, and Mann-Kendall test. In other words, the significant intensification of humidity in Qinghai since 2003 is closely related to the ongoing intensification of the EASM and the westerly wind circulation, with the latter contributing considerably. These findings confirm the view of warming and humidification in northwest China and provide a reliable time point for discussing warming and humidification in northwest China.

Effect of nasal high-flow oxygen humidification on patients after cardiac surgery.

Background: Although high-flow humidified oxygen therapy (HFNC) has emerged as an important treatment for respiratory failure, few studies have reported on whether HFNC is appropriate for patients with hypoxemia after cardiac surgery, and the clinical efficacy of HFNC in patients undergoing cardiac surgery is unclear. Objective: To investigate the clinical effect of HFNC after cardiac surgery. Methods: Convenience sampling was used to select 76 patients who underwent invasive mechanical ventilation and oxygen therapy after valve replacement or coronary artery bypass grafting from July 2019 to June 2021. The patients were divided into the routine group and the HFNC group according to the oxygen therapy provided after the operation. The patients in the routine group (N = 38) were treated with oxygen inhalation by face mask after the operation, while those in the HFNC group (N = 38) were treated with HFNC via nasal cavity. The arterial partial pressure of oxygen (PaO2), the arterial partial pressure of carbon dioxide (PaCO2) and the oxygenation index (OI) were observed and compared between the two groups at 6 h, 12 h and 24 h after treatment. The sputum viscosity, incidence of second intubation and the intensive care unit (ICU) stay time were evaluated. Results: The difference in PaCO2 between the two groups was statistically significant at 24 h after treatment (p < 0.05). The PaO2 in the HFNC group was significantly higher than in the routine group at 24 h after treatment, and the OI of the routine group was lower than in the HFNC group at 6 h, 12 h and 24 h after treatment (p < 0.05). The sputum viscosity in the HFNC group was better than in the routine group at 12 h and 24 h after treatment. The second intubation rate and ICU stay time in the HFNC group were lower than in the routine group (p < 0.05). Conclusion: Compared with conventional mask oxygen inhalation, HFNC can effectively reduce sputum viscosity, improve oxygenation, reduce the incidence of repeated intubation and meet patients' comfort needs. It is an advantageous respiratory support strategy for patients after cardiac surgery compared with invasive mechanical ventilation to oxygen therapy and is beneficial to the recovery of cardiopulmonary function.

Current treatment strategies in managing side effects associated with domiciliary positive airway pressure (PAP) therapy for patients with sleep disordered breathing: A systematic review and meta-analysis.

Sleep disordered breathing is commonly treated with positive airway pressure therapy. Positive airway pressure therapy is delivered via a tight-fitting mask with common side effects including: leak, ineffective treatment, residual sleep disordered breathing, eye irritation, nasal congestion, pressure ulcers and poor concordance with therapy. This systematic review and meta-analysis aimed to identify the effectiveness of current treatment strategies for managing side effects associated with positive airway pressure therapy. Five databases were searched and 10,809 articles were screened, with 36 articles included in the review. Studies investigated: dressings, nasal spray/douche, chin straps, heated humidification and interfaces. No intervention either improved or detrimentally affected: positive airway pressure concordance, Epworth Sleepiness Score, residual apnoea hypopnea index or interface leak. The review was limited by study heterogeneity, particularly for outcome measures. Additionally, patient demographics were not reported, making it difficult to apply the findings to a broad clinical population. This review highlights the paucity of evidence supporting treatment strategies to manage side effects of positive airway pressure therapy.

Biocompatible Polymer for Self-Humidification.

Lung supportive devices (LSDs) have been extensively utilized in treating patients diagnosed with various respiratory disorders. However, these devices can cause moisture depletion in the upper airway by interfering with the natural lubrication and air conditioning process. To remedy this, current technologies implement heated humidification processes, which are bulky, costly, and nonfriendly. However, it has been demonstrated that in a breath cycle, the amount of water vapor in the exhaled air is of a similar quantity to the amount needed to humidify the inhaled air. This research proposes to trap the moisture from exhaled air and reuse it during inhalation by developing a state-of-the-art hydrophilic/hydrophobic polymer tuned to deliver this purpose. Using the atom transfer radical polymerization (ATRP) method, a substrate was successfully created by incorporating poly (N-isopropyl acrylamide) (PNIPAM) onto cotton. The fabricated material exhibited a water vapor release rate of 24.2 ± 1.054%/min at 32 °C, indicating its ability to humidify the inhaled air effectively. These findings highlight the potential of the developed material as a promising solution for applications requiring rapid moisture recovery.

Evaluation of a Novel Dry Powder Surfactant Aerosol Delivery System for Use in Premature Infants Supported with Bubble CPAP.

Aerosolized lung surfactant therapy during nasal continuous positive airway pressure (CPAP) support avoids intubation but is highly complex, with reported poor nebulizer efficiency and low pulmonary deposition. The study objective was to evaluate particle size, operational compatibility, and drug delivery efficiency with various nasal CPAP interfaces and gas humidity levels of a synthetic dry powder (DP) surfactant aerosol delivered by a low-flow aerosol chamber (LFAC) inhaler combined with bubble nasal CPAP (bCPAP). A particle impactor characterized DP surfactant aerosol particle size. Lung pressures and volumes were measured in a preterm infant nasal airway and lung model using LFAC flow injection into the bCPAP system with different nasal prongs. The LFAC was combined with bCPAP and a non-heated passover humidifier. DP surfactant mass deposition within the nasal airway and lung was quantified for different interfaces. Finally, surfactant aerosol therapy was investigated using select interfaces and bCPAP gas humidification by active heating. Surfactant aerosol particle size was 3.68 µm. Lung pressures and volumes were within an acceptable range for lung protection with LFAC actuation and bCPAP. Aerosol delivery of DP surfactant resulted in variable nasal airway (0-20%) and lung (0-40%) deposition. DP lung surfactant aerosols agglomerated in the prongs and nasal airways with significant reductions in lung delivery during active humidification of bCPAP gas. Our findings show high-efficiency delivery of small, synthetic DP surfactant particles without increasing the potential risk for lung injury during concurrent aerosol delivery and bCPAP with passive humidification. Specialized prongs adapted to minimize extrapulmonary aerosol losses and nasal deposition showed the greatest lung deposition. The use of heated, humidified bCPAP gases compromised drug delivery and safety. Safety and efficacy of DP aerosol delivery in preterm infants supported with bCPAP requires more research.

High-flow via a tracheostomy tube and speaking valve during weaning from mechanical ventilation and tracheostomy.

BACKGROUND: Weaning from mechanical ventilation and tracheostomy after prolonged intensive care consume enormous resources with optimal management not currently well described. Restoration of respiratory flow via the upper airway is essential and early cuff-deflation using a one-way valve (OWV) is recommended. However, extended OWV use may cause dry airways and thickened secretions which challenge the weaning process. High-flow therapy via the tracheostomy tube (HFT-T) humidifies inspired air and may be connected via an in-line OWV (HFT-T-OWV) alleviating these problems. We aim to provide clinical and experimental data on the safety of HFT-T-OWV along with a practical guide to facilitate clinical use during weaning from mechanical ventilation and tracheostomy. METHODS: Data on adverse events of HFT-T-OWV were retrieved from a quality register for patients treated at an intensive care rehabilitation center between 2019 and 2022. Benchtop experiments were performed to measure maximum pressures and pressure support generated by HFT-T-OWV at 25-60 L/min flow using two different HFT-T adapters (interfaces). In simulated airway obstruction using a standard OWV (not in-line) maximum pressures were measured with oxygen delivered via the side port at 1-3 L/min. RESULTS: Of 128 tracheostomized patients who underwent weaning attempts, 124 were treated with HFT-T-OWV. The therapy was well tolerated, and no adverse events related to the practice were detected. The main reason for not using HFT-T-OWV was partial upper airway obstruction using a OWV. Benchtop experiments demonstrated HFT-T-OWV maximum pressures <4 cmH2 O and pressure support 0-0.6 cmH2 O. In contrast, 1-3 L/min supplemental oxygen via a standard OWV caused pressures between 84 and 148 cmH2 O during simulated airway obstruction. CONCLUSIONS: Current study clinical data and benchtop experiments indicate that HFT-T-OWV was well tolerated and appeared safe. Pressure support was low, but humidification may enable extended use of a OWV without dry airway mucosa and thickened secretions. Results suggest the treatment could offer advantages to standard OWV use, with or without supplementary oxygen, as well as to HFT-T without a OWV, for weaning from mechanical ventilation and tracheostomy. However, for definitive treatment recommendations, randomized clinical trials are needed.

Changing characteristics of ecosystem and water storage under the background of warming and humidification in the Qilian Mountains, China.

The Qilian Mountains provide an ecological security barrier, and the region is an important river runoff area in China. Water resources play an essential role in the natural environment of Northwest China. This study used daily temperature and precipitation data from meteorological stations in the Qilian Mountains from 2003 to 2019, Gravity Recovery and Climate Experiment, and Moderate Resolution Imaging Spectroradiometer satellite data. Additionally, we used the Gravity Recovery and Climate Experiment satellite's monthly gravity field model data. Furthermore, we analyzed the characteristics of climate warming and humidification in the eastern, central, and western sections of the Qilian Mountains based on spatial precipitation interpolation and linear trend analysis. Finally, we examined the relationship between water storage changes and precipitation and its impact on vegetation ecology. The results revealed a significant warming and humidification trend in the western Qilian Mountains. The temperature increased significantly, and the increased precipitation rate in summer reached 1.5-3.1 mm/10a. Water storage in the Qilian Mountains displayed an increasing trend, with an increase of approximately 14.3 × 108 m3 over the 17 years study period, averaging an increase of 8.4 mm/year. The spatial distribution of water storage in the Qilian Mountains increased from north to south and east to west. There were noticeable seasonal differences, with the largest surplus occurring in the western Qilian Mountains (71.2 mm in summer). The fractional vegetation coverage in 95.2 % of the western Qilian Mountains and net primary productivity in 90.4 % of the area displayed an increasing trend, and vegetation ecology improved significantly. This study aims to investigate the characteristics of ecosystem and water storage changes in the Qilian Mountain area under the background of climate warming and humidification. The results obtained from this study provided an assessment of the vulnerability of alpine ecosystems and helped in making spatially explicit decisions for the rational utilization of water resources.

Water Management Capacity of Metal Foam Flow Field for PEMFC under Flooding Situation.

Porous metal foam with complex opening geometry has been used as a flow field to enhance the distribution of reactant gas and the removal of water in polymer electrolyte membrane fuel cells. In this study, the water management capacity of a metal foam flow field is experimentally investigated by polarization curve tests and electrochemical impedance spectroscopy measurements. Additionally, the dynamic behavior of water at the cathode and anode under various flooding situations is examined. It is found that obvious flooding phenomena are observed after water addition both into the anode and cathode, which are alleviated during a constant-potential test at 0.6 V. Greater abilities of anti-flooding and mass transfer and higher current densities are found as the same amount of water is added at the anode. No diffusion loop is depicted in the impedance plots although a 58.3% flow volume is occupied by water. The maximum current density of 1.0 A cm-2 and the lowest Rct around 17 mΩ cm2 are obtained at the optimum state after 40 and 50 min of operation as 2.0 and 2.5 g of water are added, respectively. The porous metal pores store a certain amount of water to humidify the membrane and achieve an internal "self-humidification" function.

Experimental Study on Humidification Coagulation and Removal of Fine Particles Using an Electrostatic Precipitator.

A wet electrostatic precipitator (WESP) has much higher capture rate for fine particulate matter, PM2.5, than a traditional dry type electrostatic precipitator does. In order to make full use of existing dust removal equipment and reduce the emissions of smoke and dust to zero, a combination of chemical coagulation and humidification coagulation is proposed using a WESP. The results show that the addition of chemical coagulant can promote the coagulation of coal-fired dust particles. After the addition of pectin (PG), the median diameter of dust particles increases from 28.19 µm to 45.28 µm. Water vapor humidification can promote the coagulation of dust particles. When the water vapor injection rate increases from 0 kg/h to 3.2 kg/h, the median diameter of dust particles increases from 28.19 µm to 36.45 µm. The synergistic effect of the coagulant and water vapor can enhance the chemical coagulation effect; when 1.0 × 10-2 g/L PG and 3.2 kg/h water vapor synergize, the collection efficiency reaches 98.17%, and when 1.0 × 10-2 g/L polyacrylamide (PAM) and 3.2 kg/h water vapor synergize, the collection efficiency reaches 96.68%. Both chemical coagulation and water vapor humidification can promote the condensation of coal dust, which is beneficial to improve the efficient capture of fine particles using WESP.