Relative Humidity Levels Research Articles

Predicting the strength development of 3D printed concrete considering the synergistic effect of curing temperature and humidity: From perspective of modified maturity model

This study aims to establish a development model for the compressive strength of 3D printed concrete (3DPC) under the coupling influence of temperature and humidity, utilizing the maturity method. Initially, diverse curing conditions were applied to 3D printed specimens, incorporating varying temperatures (10 °C, 20 °C, 40 °C) and relative humidity levels (100% RH, 80% RH, 60% RH, 40% RH), with strength value assessed at different ages. Subsequently, a maturity model for humidity modification was proposed, and the model was calibrated through experimental results. The results show that the strength of the specimens increases over time, irrespective of the variations in curing temperatures and humidity levels. Moreover, with a decrease in humidity level, a more pronounced decline in strength is observed. Furthermore, the anisotropy index values of the rate constant in the Y-direction specimen, when cured at temperatures of 10 °C and higher humidity conditions, such as 100% RH and 80% RH, exhibit significant variations across different temperatures and moisture levels, leading to increased anisotropies. The modified maturity model can be used to predict and evaluate the strength development of 3D PC under different environmental conditions with high accuracy.

Relative humidity measurements of a thin-film humidity sensor in condensing conditions in the temperature range from −40 °C to 5 °C

In condensing conditions, metastable states such as supersaturation of water vapour and supercooling of liquid water are commonly observed in the free atmosphere. This study investigates the response of a polymeric thin-film humidity sensor under condensing conditions at various temperatures (−40 °C, −20 °C, −5 °C, and 5 °C) and different relative humidity (RH) levels. To ensure precise control of RH, a saturator-based humidity generator operating in a two-temperature mode is utilized. The condensing conditions are achieved in two ways: by increasing water vapour pressure (WVP) at a fixed temperature and by decreasing the temperature while maintaining a constant WVP. In general, when measuring RH under condensing conditions, the sensor indicates a temporary supersaturation state with an RH peak exceeding 100% before the onset of condensation. Subsequently, the RH value exhibits a delayed decrease when exposed to a non-condensing RH level. The experiments with a constant WVP demonstrate a lower likelihood of ice condensation compared to those with a constant temperature. This study demonstrates the measurement capability and behaviour of thin-film humidity sensors above 100% RH in the supersaturation states that are commonly observed in the free atmosphere at meteorologically-relevant temperatures.

Environmental fatigue crack growth of PV glass/EVA laminates in the melting range

AbstractThe delamination of encapsulants in photovoltaic (PV) modules is a common issue that leads to power loss due to optical losses. Encapsulant debonding is usually examined under monotonic loading conditions subsequent to environmental exposure such as damp heat. Service‐relevant, superimposed environmental‐mechanical fatigue loads are not considered adequately. Hence, the environmental fatigue delamination resistance of thermally toughened double glass laminates with an ethylene vinyl acetate copolymer (EVA) adhesive layer was investigated in this study. Focus was given to the melting range of EVA, in which the non‐crosslinked crystalline phase fraction is already in the partly molten state. Double cantilever beam specimens were tested on an electrodynamic test machine at temperatures of 60, 70, 80, and 90°C and relative humidity (rh) levels of 2%, 30%, 50%, and 80%. The fractured surfaces were characterized by digital microscopy, Fourier transform infrared spectroscopy (FTIR), X‐ray photoelectron spectroscopy (XPS), and differential scanning calorimetry (DSC). The cyclic fatigue tests revealed a decay in delamination resistance at elevated temperature and humidity levels. At 70°C, the delamination resistance was low, regardless of the relative humidity. Most of the laminates failed by debonding. XPS analysis showed a reduction of the C=O and C–O content, along with an increase in Si–O content with increasing relative humidity. For laminates tested at 60 and 70°C, an EVA recrystallization peak was observed in DSC experiments. This peak was shifted to significantly higher temperatures at 80% rh. XPS and DSC indicated local hydrolysis within the porous fracture process zone ahead of the crack tip. Consequently, acetic acid formation led to a decrease in delamination resistance, resulting in lower fatigue threshold values. The investigations confirmed the significant impact of environmental conditions on the fatigue delamination resistance within glass/encapsulant laminates. Notably, acetic acid formation and a significant reduction in delamination properties were observed after around 100 h of environmental fatigue exposure.

The Impact of Indoor Air Humidity on the Infiltration of Ambient Particles

Ambient particles contribute to occupant exposure as they infiltrate indoor environments through building envelope cracks, impacting indoor air quality. This study investigates the impact of indoor air humidity on the infiltration of ambient particles, highlighting humidity’s crucial role in influencing particle dynamics in indoor environments. Employing a controlled chamber system, we conducted experiments to quantify the infiltration of size-resolved particles under varying relative humidity (RH) conditions. Both the total number and the mass concentration of particles increased with RH in the experimental chamber. The smallest particles (0.3–0.4 μm) experienced reduced infiltration at higher RH levels due to hygroscopic growth, while intermediate-sized particles showed increased infiltration, resulted from coagulation effects. Large particles (>1.0 μm) demonstrated reduced infiltration factors, caused by lower penetration and higher deposition rates, with minimal impact from RH changes. Our findings reveal that RH influences particle hygroscopic growth, deposition rate, and coagulation process, thereby affecting indoor particle size distribution and concentration.

Optimization of inoculum production of Stemphylium botryosum for large-scale resistance screening of lentils

BackgroundStemphylium blight incited by Stemphylium botryosum poses a significant threat to lentil crops worldwide, inducing severe defoliation and causing substantial yield losses in susceptible varieties under favorable conditions. While some moderate levels of resistance have been identified within lentil germplasm, a low number of resistant cultivars are available to farmers. Adding to the common constraints of resistance breeding, a notable challenge is generating a sufficient number of spores for large-scale screenings, which are essential for pinpointing additional sources of resistance for integration into breeding programs. Therefore, there is a pressing need to improve existing screening methods and tailor them for large-scale material selection. In pursuit of this objective, a protocol for the efficient production of fungal material has been adapted.ResultsOptimization of fungal material production was successfully achieved by comparing the use of fungal mycelia and spores. Spore production was found to be optimal when produced on solid V8-PDA(hi) medium, while liquid Richard’s medium was identified as superior for mycelium yield. Furthermore, a refined screening method was developed by evaluating the resistance of six lentil accessions to stemphylium blight. This assessment included the use of either fungal mycelia (at densities ranging from 1 to 5 g L− 1) or spores (with densities ranging from 5 × 104 to 2 × 105 conidia mL− 1) under three different relative humidity levels (from 50 to 100%). Both humidity levels and inoculum dose significantly influenced the final disease rating (DR) and the relative Area Under the Disease Progress Curve (rAUDPC). Differences among genotypes in final symptom severity (DR) became more pronounced after inoculation with inoculum densities of 5 g L− 1 of mycelium or of 105 and 2 × 105 conidia mL− 1 of spore under 100% relative humidity. Given the challenges associated with the large-scale production of S. botryosum spores, inoculations with 5 g L− 1 of mycelium is highly recommended as a practical alternative for conducting mass-scale screenings.ConclusionsThe findings from this study underscore the critical importance of maintaining high level of humidity during inoculation and disease progression development for accurately assessing resistance to stemphylium blight. The optimization of mycelial production for suspension inoculation emerges as a more reliable and efficient approach for conducting large-scale screening to assess germplasm resistance against stemphylium blight in lentil crops.

Climatically Accelerated Material Processes Determining the Long-Term Reliability of Light-Emitting Diodes.

LEDs (Light-Emitting Diodes) are widely applied not only in decorative illumination but also in everyday lighting in buildings, flats, public areas, and automotive fields. These application areas often mean harsh environments, for example, regarding the humidity content of the surrounding air: besides outdoor and automotive illumination, even the household use cases (kitchen, bathroom, cellar) may represent extreme temperature and humidity variations (often reaching relative humidity levels close to 100%) for these devices; thus, their reliability behaviour in such circumstances should be better understood. Thermally activated processes were studied in several previous publications, but less information is available regarding high-humidity environmental tests. Moisture and temperature ageing tests with appropriate environmental parameter settings were performed as accelerated lifetime tests to investigate not only the effect of temperature but also that of humidity on the ageing and reliability of LED packages containing RGB (red green blue) chips and phosphor-converted white (pcW) LEDs. The ageing was followed not only through monitoring optical/electrical/spectral parameters but also with material analysis. Moisture-material interaction models were proposed and set up. It was found that humidity-accelerated ageing processes are more severe than expected from previous assumptions. RGB and pcW LEDs showed strongly different behaviour.

Hydrolysis of Cellulose Acetate Phthalate and Hydroxypropyl Methylcellulose Phthalate in Amorphous Solid Dispersions

The preparation of amorphous solid dispersions (ASDs) represents a promising strategy for addressing the solubility limitations of poorly soluble drugs, facilitating enhanced absorption. Acidic polymers such as cellulose acetate phthalate (CAP) and hydroxypropyl methylcellulose phthalate (HPMCP) have emerged as effective carriers for ASDs. Although the hydrolytic degradation of these polymers has been documented, its impact on the stability of ASDs has not been systematically investigated. This research aimed to explore the potential hydrolysis of CAP and HPMCP and how it influences the stability of ASDs containing ketoconazole (KTZ), at drug loadings of 10 % and 50 %. Our study utilized thermal analysis, infrared spectroscopy, and evaluations of physical and chemical stability. The results revealed that although KTZ remained physically stable in all ASDs over a 60-day period under various stability conditions, the emergence of crystalline phthalic acid (PA), a byproduct of polymer hydrolysis, was observed at elevated temperatures and relative humidity levels. The acidic microenvironment fostered by the release of PA further catalyzed drug chemical degradation. This study underscores the susceptibility of CAP and HPMCP to hydrolytic degradation, highlighting the inherent risk of PA-induced drug degradation, particularly for acid-labile compounds. These insights into the understanding of polymer hydrolysis in ASDs pave the way for the development of targeted approaches to safeguard drug stability and optimize pharmaceutical formulations for enhanced bioavailability, efficacy, and safety.

Multichannel Hierarchical Analysis of Time-Resolved Hyperspectral Data for Advanced Colorimetric E-Nose.

The colorimetric sensor-based electronic nose has been demonstrated to discriminate specific gaseous molecules for various applications, including health or environmental monitoring. However, conventional colorimetric sensor systems rely on RGB sensors, which cannot capture the complete spectral response of the system. This limitation can degrade the performance of machine learning analysis, leading to inaccurate identification of chemicals with similar functional groups. Here, we propose a novel time-resolved hyperspectral (TRH) data set from colorimetric array sensors consisting of 1D spatial, 1D spectral, and 1D temporal axes, which enables hierarchical analysis of multichannel 2D spectrograms via a convolution neural network (CNN). We assessed the outstanding classification performance of the TRH data set compared to an RGB data set by conducting a relative humidity (RH) concentration classification. The time-dependent spectral response of the colorimetric sensor was measured and trained as a CNN model using TRH and RGB sensor systems at different RH levels. While the TRH model shows a high classification accuracy of 97.5% for the RH concentration, the RGB model yields 72.5% under identical conditions. Furthermore, we demonstrated the detection of various functional volatile gases with the TRH system by using experimental and simulation approaches. The results reveal distinct spectral features from the TRH system, corresponding to changes in the concentration of each substance.

Heat Transfer by Sweat Droplet Evaporation.

Sweating regulates the body temperature in extreme environments or during exercise. Here, we investigate the evaporative heat transfer of a sweat droplet at the microscale to unveil how the evaporation complexity of a sweat droplet would affect the body's ability to cool under specific environmental conditions. Our findings reveal that, depending on the relative humidity and temperature levels, sweat droplets experience imperfect evaporation dynamics, whereas water droplets evaporate perfectly at equivalent ambient conditions. At low humidity, the sweat droplet fully evaporates and leaves a solid deposit, while at high humidity, the droplet never reaches a solid deposit and maintains a liquid phase residue for both low and high temperatures. This unprecedented evaporation mechanism of a sweat droplet is attributed to the intricate physicochemical properties of sweat as a biofluid. We suppose that the sweat residue deposited on the surface by evaporation is continuously absorbing the surrounding moisture. This route leads to reduced evaporative heat transfer, increased heat index, and potential impairment of the body's thermoregulation capacity. The insights into the evaporative heat transfer dynamics at the microscale would help us to improve the knowledge of the body's natural cooling mechanism with practical applications in healthcare, materials science, and sports science.

Experimental study of relative humidity absorbed through capillarity of building material under isothermal conditions: Clay-Kaolin reinforced with Alfa fibers

The research article aims to investigate the hygroscopic behavior of water absorbed by capillarity in clay supplemented with Alfa fibers. This specific clay-fiber composite holds significant importance in Moroccan construction practices. The primary aim is to enhance comprehension and control over the material's hydrothermal behavior by investigating moisture absorption traits, responses to varying humidity and temperature conditions, and the influence of fiber reinforcement on moisture equilibrium and structural stability. As temperature levels rise, the equilibrium water content absorbed through capillarity demonstrates a downward trend. The introduction of Kaolin-Alfa fibers into the clay composite profoundly affects the pace at which equilibrium moisture content is lost. This attribute effectively mitigates the likelihood of cracks developing in earthen structures during the drying phase, as it uniformly disperses tensions resulting from shrinkage. The findings showed that by understanding its unique region, Predictions regarding the sorption tendencies of other building materials are possible because of the approximate estimation of Clay-Kaolin reinforced with Alfa fibers sorption behavior. Surface flaws arise on Clay-Kaolin reinforced with Alfa fibers as a result of rising average pore radius and spreading pressure brought on by rising temperature and relative humidity. Furthermore, the heightened average pore volume observed in regions characterized by elevated relative humidity levels precipitates various defects within building materials, a phenomenon that has a discernible impact on their durability.

Abstract 2063: Using the edge wells in 96-well plates without increasing variability in cytotoxicity assays through thermal controls

Abstract There are very few things as fundamental to cancer research as the 96-well-plate, yet edge effect has continued to cause problems since its introduction. The most common remedy for edge effect is to avoid using edge wells altogether, which eliminates 37% of the plate from the assay. If all of those wells could be used, an estimated USD $119M could be saved in research costs annually across the globe. We have shown previously that maintaining constant thermal control of plating conditions reduces variability in stem cell toxicity assays. Here, we ask the question: can we use the edge wells in cancer screening assays if we control thermal changes that happen in the traditional lab as cells are plated at room temperature and incubated at 37 degrees C? We had the null hypothesis that including the edge wells would add variability to an A549 cytotoxicity assay, even if the cell handling and incubation temperatures were matched and held constant. We plated A549 cells at either room temperature (like a BSC) or at 37 degrees C using the Xvivo System, which maintains constant temperature, oxygen, CO2, and relative humidity levels around cell handling operations. The cells were treated with serial dilutions of peracetic acid/hydrogen peroxide solution. After incubation for 3 days, the plates were stained with Crystal Violet and assessed for cell density (n=3 separate experiments). The null hypothesis was disproven. We found that if the plates were maintained at 37 degrees C during cell handling as well as incubation, that cell distribution was random and even across all wells, even edge wells. We found that there was no statistical difference between edge well and center well results in cytotoxicity assays. Edge wells were usable without increasing variability in the assays. This is consistent with earlier findings showing that when temperature changes between cell plating and incubation were averted, stem cell distribution across the plate was random and the edge effect was eliminated. Citation Format: Alicia D. Henn, Shannon Darou, Randy Yerden. Using the edge wells in 96-well plates without increasing variability in cytotoxicity assays through thermal controls [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2063.

Adsorption isotherm of building materials at different temperatures: A review and measurement

The temperature dependency of the adsorption isotherm renders its significance as one of the primary input parameters in models dealing with moisture transport. The present study involved the determination of the adsorption isotherm of sixteen building materials from various categories, including cladding, building paper, wood, sheathing boards, and insulations. The measurements were conducted under nine climatic conditions, a combination of three temperatures (3 °C (37.4 °F), 21 °C (69.8 °F), 45 °C (113 °F)) and three relative humidity levels (50%, 70%, 90%). The study indicated that relative humidity increased the building materials’ equilibrium moisture content (EMC). In opposition, an increase in temperature decreased the EMC of the tested materials. It was discovered that cellulose fiber and wood-based materials had a greater capacity to store moisture than others. Conversely, the minimum moisture content was observed in brick, Densglass gold gypsum, and EPS products. Furthermore, we used the ABC model as an adaptable mathematical equation for a novel nonlinear surface fitting of adsorption isotherms of tested materials to make optimal use of the experimental data and effectively analyze the simultaneous impact of all temperatures and relative humidities. Tested against the measured experimental data, we obtained the best R-squared values from the second-order polynomial Equation.

Impact of thermal conductivity of aerogel-enhanced insulation materials on building energy efficiency in environments with different temperatures and humidity levels

New building thermal insulation materials, such as aerogel-enhanced insulation materials, are constantly emerging. To study how cement-based aerogel-enhanced thermal insulation materials perform under temperature and humidity changes, various aerogel-enhanced hollow glass microsphere insulation boards (HGBs) have been developed as building thermal insulation materials. The thermal conductivity of aerogel-enhanced HGBs, expanded polystyrene (EPS), and foamed cement (FC) was measured at various relative humidity levels and temperatures, and the summer cooling load of buildings with aerogel-enhanced HGBs, EPS, or FC as the insulation layer was simulated for different building heights and thermal zones. The results show that (1) the new aerogel-enhanced HGB materials are more suitable for building insulation in humid and hot areas than FC; (2) the cooling load of small buildings with fewer floors is more sensitive to the variation in the thermal conductivity with temperature and humidity; (3) for buildings in areas with hot summers and warm winters, the impact of the outdoor relative humidity should be fully considered when calculating summer cooling loads.

Impacts of Northward Typhoons on Autumn Haze Pollution Over North China Plain

AbstractAlthough air quality in China has improved substantially over recent years, haze pollution events still occur frequently, especially over the North China Plain (NCP). Previous studies showed that typhoons are conducive to regional pollution events in eastern China; however, the underlying mechanism and quantitative understanding of the typhoons' impact on haze pollution remain unclear there. Here, based on ground‐based and satellite observations, reanalysis data, and model simulations, we show that northward typhoons approaching China are essential for autumn haze pollution over NCP. Elevated relative humidity levels and enhanced pollution accumulation, caused by northward typhoons and the corresponding high‐pressure systems, are responsible for the pollution enhancements over NCP. Compared with episodes without typhoon influence, cities near Taihang and Yan Mountain suffer from heavier haze pollution when typhoons approach, with PM2.5 concentrations increasing from 87.1 to 106.4 μg m−3. More water vapor from the Yellow and Bohai Seas and pollutants from eastern China are transported to these cities by typhoon‐induced southeasterly wind anomalies, facilitating the chemical formation of aerosols there. In addition, by the block of mountains, these southeasterly wind anomalies also lead to stronger local accumulation over cities and an elevation of pollutants along the mountains. What is more, with the implementation of emission reduction, the relative changes of PM2.5 concentrations between typhoon‐induced episodes and no‐typhoon episodes increase. This work highlights the importance of understanding the impact of synoptical weather on PM2.5 transport, accumulation, and formation processes in haze pollution mitigation in eastern China.

Effects of humidity and temperature on quality factor of micro-beam resonators in atmospheric pressure and gas rarefaction

At atmospheric pressure (p=101325 Pa), the effects of humidity and temperature on moist air become important when discussing the quality factor of micro-cantilever and micro-bridge resonators. The squeeze film damping (SFD) problem, the dominant damping source for micro-beam resonators, is modelled using the modified molecular gas lubrication (MMGL) equation with finite element modelling (FEM) in the eigenvalue problem. The MMGL equation is modified with the effective viscosity of moist air (μeff) to account for the effects of humidity and temperature. Other damping sources, such as thermoelastic damping (TED) and the support loss of micro-beam resonators, are also calculated. The quality factor of micro-beam resonators is then discussed over a wide range of temperatures and relative humidity levels at atmospheric pressure and gas rarefaction. The results show that the quality factor of micro-cantilever and micro-bridge resonators increases as both humidity and temperature rise in atmospheric pressure and gas rarefaction. Furthermore, the quality factor of a micro-bridge resonator with changes in humidity and temperature is significantly higher than that of a micro-cantilever resonator in atmospheric pressure and gas rarefaction.

Half of the 18O enrichment of leaf sucrose is conserved in leaf cellulose of a C3 grass across atmospheric humidity and CO2 levels.

The 18O enrichment (Δ18O) of cellulose (Δ18OCel) is recognized as a unique archive of past climate and plant function. However, there is still uncertainty regarding the proportion of oxygen in cellulose (pex) that exchanges post-photosynthetically with medium water of cellulose synthesis. Particularly, recent research with C3 grasses demonstrated that the Δ18O of leaf sucrose (Δ18OSuc, the parent substrate for cellulose synthesis) can be much higher than predicted from daytime Δ18O of leaf water (Δ18OLW), which could alter conclusions on photosynthetic versus post-photosynthetic effects on Δ18OCel via pex. Here, we assessed pex in leaves of perennial ryegrass (Lolium perenne) grown at different atmospheric relative humidity (RH) and CO2 levels, by determinations of Δ18OCel in leaves, Δ18OLGDZW (the Δ18O of water in the leaf growth-and-differentiation zone) and both Δ18OSuc and Δ18OLW (adjusted for εbio, the biosynthetic fractionation between water and carbohydrates) as alternative proxies for the substrate for cellulose synthesis. Δ18OLGDZW was always close to irrigation water, and pex was similar (0.53 ± 0.02 SE) across environments when determinations were based on Δ18OSuc. Conversely, pex was erroneously and variably underestimated (range 0.02-0.44) when based on Δ18OLW. The photosynthetic signal fraction in Δ18OCel is much more constant than hitherto assumed, encouraging leaf physiological reconstructions.

Environmental causality calibration: Advancing WLAN RF fingerprinting for precise indoor localization.

In recent years, considerable and valuable research progress has been made in indoor positioning technologies based on WLAN Radio Frequency (RF) fingerprinting, identifying it as one of the most promising positioning technologies with substantial potential for wider adoption. However, indoor environmental factors significantly influence the propagation of wireless RF signals, resulting in a considerable decrease in positioning accuracy as the indoor environmental conditions vary. Thus, effectively mitigating the impact of indoor environmental factors on WLAN RF fingerprinting-based positioning systems has become a crucial research problem. Currently, there is a dearth of comprehensive research on the influence of indoor climatic factors, particularly the variations in relative humidity, on the propagation of WLAN RF signals within indoor spaces and its consequential impact on positioning accuracy. To address the aforementioned issues, this paper proposes an Adaptive expansion fingerprint database (AeFd) model based on a regression learning algorithm. The AeFd, through the design of a relationship model describing the interaction between fingerprint databases under varying relative humidity, allows the fingerprint database expanded by AeFd to dynamically adapt to the changes in indoor relative humidity. Our experiments show that using the AeFd model with the KNN algorithm, a 5% performance improvement was observed over 10 days and an 8% improvement over 10 months. According to experimental test results, the fingerprint database expansion model AeFd proposed in this paper can effectively expand the fingerprint database under different relative humidity levels, thereby significantly enhancing the positioning performance of the system and improving its stability.

The Effects of Ambient Temperature and Atmospheric Humidity on the Diffusion Dynamics of Hydrogen Fluoride Gas Leakage Based on the Computational Fluid Dynamics Method.

In order to investigate the impact of environmental temperature and atmospheric humidity on the leakage and diffusion of hydrogen fluoride (HF) gas, this study focused on the real scenario of an HF chemical industrial park. Based on the actual dispersion scenario of HF gas, a proportionally scaled-down experimental platform for HF gas leakage was established to validate the accuracy and feasibility of numerical simulations under complex conditions. Using the validated model, the study calculated the complex scenarios of HF leakage and diffusion within the temperature range of 293 K to 313 K and the humidity range of 0% to 100%. The simulation results indicated that different environmental temperatures had a relatively small impact on the hazardous areas (the lethal area, severe injury area, light injury area, and maximum allowable concentration (MAC) area) formed by HF gas leakage. At 600 s of dispersion, the fluctuation range of hazardous area sizes under different temperature conditions was between 3.11% and 13.07%. In contrast to environmental temperature, atmospheric relative humidity had a more significant impact on the dispersion trend of HF leakage. Different relative humidity levels mainly affected the areas of the lethal zone, light injury zone, and MAC zone. When HF continued to leak and disperse for 600 s, compared to 0% relative humidity, 100% relative humidity reduced the lethal area by 35.7%, while increasing the light injury area and MAC area by 27.26% and 111.6%, respectively. The impact on the severe injury area was relatively small, decreasing by 1.68%. The results of this study are crucial for understanding the dispersion patterns of HF gas under different temperature and humidity conditions.

Unlocking the Mystery of Aerosol Phase Transitions Governed by Relative Humidity History Through an Advanced Outdoor Nephelometer System

AbstractThis study introduces an innovative outdoor nephelometer system designed to monitor the dynamic hygroscopic behavior of aerosols in ambient air. Field measurements conducted in the Pearl River Delta region of China unveil significant roles of relative humidity (RH) swings on aerosol phase states. Highlighting the occurrence of aerosol crystallization in the afternoon followed by gradual deliquescence as RH increases, particularly when minimum afternoon RH drops below 35%, with no such behavior observed when it exceeds 40%. Emphasizing that aerosol phase states are shaped not only by RH and chemical composition but also by their RH history, illustrating that RH levels of 70% in the morning or evening may correspond to fully dissolved metastable or partially dissolved metastable states of ambient aerosols. These findings underscore the need to account for RH history when predicting aerosol phase states and have broader implications for comprehending aerosol behavior and its atmospheric impacts.

The impact of short-term exposure to meteorological factors on the risk of death from hypertension and its major complications: a time series analysis based on Hefei, China.

This study aimed to reveal the short-term impact of meteorological factors on the mortality risk in hypertensive patients, providing a scientific foundation for formulating pertinent prevention and control policies. In this research, meteorological factor data and daily death data of hypertensive patients in Hefei City from 2015 to 2018 were integrated. Time series analysis was performed using distributed lag nonlinear model (DLNM) and generalized additive model (GAM). Furthermore, we conducted stratified analysis based on gender and age. Relative risk (RR) combined with 95% confidence interval (95% CI) was used to represent the mortality risk of single day and cumulative day in hypertensive patients. Single-day lag results indicated that high daily mean temperature (T mean) (75th percentile, 24.9°C) and low diurnal temperature range (DTR) (25th percentile, 4.20°C) levels were identified as risk factors for death in hypertensive patients (maximum effective RR values were 1.144 and 1.122, respectively). Extremely high levels of relative humidity (RH) (95th percentile, 94.29%) reduced the risk of death (RR value was 0.893). The stratified results showed that the elderly and female populations are more susceptible to low DTR levels, whereas extremely high levels of RH have a more significant protective effect on both populations. Overall, we found that exposure to low DTR and high T mean environments increases the risk of death for hypertensive patients, while exposure to extremely high RH environments significantly reduces the risk of death for hypertensive patients. These findings contribute valuable insights for shaping targeted prevention and control strategies.