Simulating atmospheric drought: Silica gel packets dehumidify mesocosm microclimates

As global temperatures rise, droughts are becoming more frequent and severe. To predict how drought might affect plant communities, ecologists have traditionally designed drought experiments with controlled watering regimes and rainout shelters. Both treatments have proven effective for simulating soil drought. However, neither are designed to directly modify atmospheric drought. Here, we detail the efficacy of a silica gel atmospheric drought treatment in outdoor mesocosms with and without a co-occurring soil drought treatment. At California State University, Los Angeles, we monitored relative humidity, temperature, and vapor pressure deficit every 10 min for 5 months in bare-ground, open-top mesocosms treated with soil drought (reduced watering) and/or atmospheric drought (silica dehumidification packets suspended 12 cm above soil). We found that silica packets dehumidified these mesocosm microclimates most effectively (-5% RH) when combined with reduced soil water, regardless of the ambient humidity levels of the surrounding air. Further, packets increased microclimate vapor pressure deficit most effectively (+0.4 kPa) when combined with reduced soil water and ambient air temperatures above 20°C. Finally, packets simulated atmospheric drought most consistently when replaced within 3 days of deployment. Our results demonstrate the use of silica packets as effective dehumidification agents in outdoor drought experiments. We emphasize that incorporating atmospheric drought in existing soil drought experiments can improve our understandings of the ecological impacts of drought.

Effect of humidity on postmortem changes in rats

IMPORTANCE

In veterinary forensic science, accurately determining the postmortem interval (PMI) is crucial for identifying the causes of animal deaths. Autolysis, a significant postmortem process, influences PMI estimation, but its relationship with humidity is not well understood.

OBJECTIVE

This study aimed to improve the accuracy of PMI estimates in veterinary forensic cases by looking into how different humidity levels affect autolysis in different organs of rats.

METHODS

The study involved 38 male rats, examining histopathological changes in their heart, liver, and pancreas. These organs were subjected to controlled humidity levels (20%, 55%, and 80%) at a constant 22°C. Tissue samples were collected at several intervals (0 h, 12 h, 24 h, 3 days, and 8 days) for comprehensive analysis.

RESULTS

Distinct autolytic characteristics in animal organs emerged under varying humidity conditions. The low-humidity environment rapidly activated autolysis more than the high-humidity environment. In addition, it was found that lower humidity caused nuclear pyknosis, cytoplasmic disintegration, and myofiber interruption. The liver, in particular, showed portal triad aggregation and hepatocyte individuation. The pancreas experienced cell fragmentation and an enlarged intracellular space. High humidity also caused the loss of striations in cardiac tissues, and the liver showed vacuolation. Under these conditions, the pancreas changed eosinophilic secretory granules.

CONCLUSIONS AND RELEVANCE

The study successfully established a clear connection between the autolytic process in PMIs and relative humidity. These findings are significant for developing a more accurate and predictable method for PMI estimation in the field of veterinary forensic science.

Impact of PM2.5, relative humidity, and temperature on sleep quality: a cross-sectional study in Taipei

INTRODUCTION

TWe investigated impacts of particulate matter with an aerodynamic diameter of less than 2.5 μm (PM2.5), relative humidity (RH), and temperature on sleep stages and arousal.

MATERIALS AND METHODS

A cross-sectional analysis involving 8,611 participants was conducted at a sleep center in Taipei. We estimated individual-level exposure to RH, temperature, and PM2.5 over 1-day, 7-day, and 30-day periods. Linear regression models assessed the relationship between these environmental factors and sleep parameters across different seasons. Mediation analysis was used to explore PM2.5, RH, and temperature roles in these relationships.

RESULTS

A 1% increase in RH over 1 and 7 days was associated with changes in non-rapid eye movement (NREM) sleep stages and increases in the arousal index across all seasons. A 1°C increase in temperature over similar periods led to increases in rapid eye movement (REM) sleep. During cold season, changes in RH and temperature were linked to variations in arousal and NREM sleep stages. In hot season, RH and temperature increases were correlated with changes in NREM sleep stages and arousal. Across all groups, a 1-μg/m³ increase in PM2.5 levels was associated with alterations in NREM and REM sleep stages and increases in the arousal index. We found PM2.5 levels mediated relationships between RH, temperature, and various sleep stages, particularly in cold season.

CONCLUSIONS

Lower RH and temperature, contributing to deep sleep reduction and increased arousal, were influenced by elevated PM2.5 exposure, especially during colder months. Enhancing environmental quality and reducing PM2.5 levels may lead to improved sleep quality.

Simulating atmospheric drought: Silica gel packets dehumidify mesocosm microclimates

1. As global temperatures rise, droughts are becoming more frequent and severe. To predict how drought might affect plant communities, ecologists have traditionally designed experiments with controlled watering regimes and rainout shelters. Both treatments have proven effective for simulating soil drought. However, neither are designed to directly modify atmospheric drought. 2. Here, we detail the efficacy of a silica gel atmospheric drought treatment in outdoor mesocosms with and without a cooccurring soil drought treatment. At California State University, Los Angeles, we monitored relative humidity (RH), temperature, and vapor pressure deficit (VPD) every 10 minutes for five months in a bare-ground experiment featuring mesocosms treated with soil drought (reduced watering) and/or atmospheric drought (silica packets suspended 12 cm above soil). 3. We found that silica packets dehumidified these microclimates most effectively (-5% RH) when combined with reduced soil water, regardless of the ambient humidity levels of the surrounding air. Further, packets increased microclimate VPD most effectively (+0.4 kPa) when combined with reduced soil water and ambient air temperatures above 20°C. Finally, packets simulated atmospheric drought most consistently when replaced within three days of deployment. 4. Our results demonstrate the use of silica packets as effective dehumidification agents in outdoor drought experiments. We emphasize that incorporating atmospheric drought in existing soil drought experiments can improve our understandings of the ecological impacts of drought.

Garage-Fabricated, Ultrasensitive Capacitive Humidity Sensor Based on Tissue Paper

The role of humidity sensors in different industries and field applications, such as agriculture, food monitoring, biomedical equipment, heating, and ventilation, is well known. However, most commercially available humidity sensors are based on polymers or electronic materials that are not degradable and thus contribute to electronic waste. Here, we report a low-cost, flexible, easy-to-fabricate, and eco-friendly parallel-plate capacitive humidity sensor for field applications. The sensor is fabricated from copper tape and tissue paper, where copper tape is used to create the plates of the capacitor, and tissue paper is used as a dielectric sensing layer. Along with the low cost, the high sensitivity, better response and recovery times, stability, and repeatability make this sensor unique. The sensor was tested for relative humidity (RH), ranging from 40% to 99%, and the capacitance varied linearly with RH from 240 pF to 720 pF, as measured by an Arduino. The response time of the sensor is ~1.5 s, and the recovery time is ~2.2 s. The experiment was performed 4-5 times on the same sensor, and repeatable results were achieved with an accuracy of ±0.1%. Furthermore, the sensor exhibits a stable response when tested at different temperatures. Due to the above advantages, the presented sensor can find ready applications in different areas.

Moisture Adsorption-Desorption Behaviour in Nanocomposite Copolymer Films

Dehumidifying air via refrigerant cooling method consumes a tremendous amount of energy. Independent humidity control systems using desiccants have been introduced to improve energy efficiency. This research aimed to find an alternative to the commonly used solid desiccant, silica gel, which has weak physical adsorption properties. It also aimed to overcome the limitation of liquid desiccants that may affect indoor air quality and cause corrosion. This study reports on the synthesis of poly(vinyl alcohol-co-acrylic acid), P(VA-AA), through solution polymerisation by hydrolysing poly(vinyl acetate-co-acrylic acid), P(VAc-AA). This viable copolymer was then incorporated with graphene oxide (GO) at different concentrations (0 wt.%, 0.5 wt.%, 2 wt.% and 5 wt.%) to enhance the adsorption-desorption process. The samples were tested for their ability to adsorb moisture at different levels of relative humidity (RH) and their capability to maintain optimum sorption capacity over 10 repeated cycles. The nanocomposite film with 2% GO, P(VA-AA)/GO2, exhibited the highest moisture sorption capacity of 0.2449 g/g for 60-90% RH at 298.15 K, compared to its pristine copolymer, which could only adsorb 0.0150 g/g moisture. The nanocomposite desiccant demonstrated stable cycling stability and superior desorption in the temperature range of 318.15-338.15 K, with up to 88% moisture desorption.

Dynamics and Viability of Airborne Respiratory Syncytial Virus under Various Indoor Air Conditions

The factors governing the viability of airborne viruses embedded within respiratory particles are not well understood. This study aimed to investigate the relative humidity (RH)-dependent viability of airborne respiratory syncytial virus (RSV) in simulated respiratory particles suspended in various indoor air conditions. We tested airborne RSV viability in three static indoor air conditions, including sub-hysteresis (RH < 39%), hysteresis (39% < RH < 65%), and super-hysteresis (RH > 65%) air as well as in three dynamic indoor air conditions, including the transitions between the static conditions. The dynamic conditions were hysteresis → super-hysteresis → hysteresis, sub-hysteresis → hysteresis, and super-hysteresis → hysteresis. We found that after 45 min of particle aging in static conditions, the viability of RSV in sub-hysteresis, hysteresis, and super-hysteresis air was 0.72% ± 0.06%, 0.03% ± 0.006%, and 0.27% ± 0.008%, respectively. After 45 min of aging in dynamic conditions, the RSV viability decreased for particles that remained in a liquid (deliquesced) state during aging when compared with particles in a solid (effloresced) state. The decreased viability of airborne RSV for deliquesced particles is consistent with prolonged exposure to elevated aqueous solutes. These results represent the first measurements of the survival of airborne RSV over particle aging time, with equal viability in low, intermediate, and high RHs at 5 and 15 min and a V-shaped curve after 45 min.

Investigation of the Compressive Strength and Void Analysis of Cement Pastes with Superabsorbent Polymer

This study aimed to experimentally investigate the compressive strength and air voids of cement pastes with varying dosages of Superabsorbent Polymer (SAP) and water-to-cement (w/c) ratios. Cement pastes were prepared using three different w/c ratios of 0.4, 0.5, and 0.6, along with different dosages of SAP ranging from 0.2% to 0.5% by weight of cement. Additionally, SAP was introduced in two forms: dry and wet. After casting the cubes, two distinct curing conditions were employed: curing at a temperature of 20 °C with a Relative Humidity (RH) of 60% (Curing 1), and water curing (Curing 2). The results revealed that the addition of SAP increased early strength when subjected to Curing 1, followed by a decrease in later strength. On the other hand, samples with SAP and water curing exhibited higher strength compared to those without SAP, especially with w/c ratios of 0.4 and 0.5. However, at a w/c ratio of 0.6, nearly all samples showed a reduction in strength compared to those without SAP. Furthermore, air void analysis was performed on all samples cured for 28 days using an image analysis technique. The samples containing wet SAP resulted in a higher total air content compared to the samples with dry SAP. Additionally, the incorporation of wet SAP in cement paste led to lower specific surface areas and a higher spacing factor than the samples with dry SAP. These findings suggest that the clumping of wet SAP particles during presoaking resulted in coarser air voids compared to the samples containing dry SAP.

Influence of Incubation Temperature and Relative Humidity on the Egg Hatchability Pattern of Two-Spotted (Gryllus bimaculatus) and House (Acheta domesticus) Crickets

This study aimed to determine the influence and optimal conditions of incubation temperature and relative humidity (RH) on the egg hatchability patterns of two-spotted (Gryllus bimaculatus) and house (Acheta domesticus) crickets. Experiment I involved 100 cricket eggs per hatching box for each species, with six replications for each controlled incubation temperature of 23, 25, 27, 29, 30, 31, 32, and 33 °C at 70% RH. Experiment II used all the same procedures as Experiment I, except for incubation temperatures of 29, 30, 31, and 32 °C tested with varied RH levels of 65%, 70%, and 75%. In Experiment I, two-spotted crickets (9.47 ± 1.99 days) exhibited faster hatching than house crickets (13.70 ± 2.78 days). Additionally, the onset of hatching decreased with higher incubation temperatures for both types of crickets. In Experiment II, an incubation temperature of 31 °C and 70% RH resulted in a hatching rate of 79.75% for two-spotted crickets, with hatching beginning in 6 days. For house cricket eggs, the optimal conditions of 30 °C and 65-75% RH led to a peak daily hatching rate of 62.00-65.50% and hatching onset in 12 days. Thus, this study established the optimal incubation temperature and RH for egg hatching of two-spotted and house crickets.

Microclimate of Brown Bear (Ursus arctos L.) Dens and Denning Area

The aim of this study was to determine the microclimate of brown bear dens depending on their size, their status (active or inactive), and the location of the den. The study included five dens of different sizes and locations in the Velebit Mountains, in the Dinaric Alps. The measurements of air temperature (°C) and relative humidity (%) in dens and the forest stands were carried out over 182 days. The absolute minimum air temperature in inactive dens was between -2.88 °C and -0.38 °C and belonged to the dens with shorter tunnels and without chambers. The exception was inactive den 1, which was situated in a thermophilic forest. No negative absolute minimum air temperatures were recorded in active dens. The absolute minimum air temperatures in the forest stands were lower than in the dens. The relative humidity was significantly higher in all dens than in the forest stands. Dens with a large entrance opening and a short tunnel were strongly influenced by the local microclimate of the forest stand. The greatest temperature difference (den-forest) was between elongated dens with chambers and the associated forest stand, while the smallest temperature differences occurred in dens with a short tunnel, without a chamber, and at the northern exposure. The greatest differences in relative humidity (den-forest) were found in dens with chambers. The den temperatures correlated with the air temperatures in the forest stands.

[Characteristics of Key Size Spectrum of PM2.5 Affecting Winter Haze Pollution in Taiyuan]

PM_2.5 is generally considered as a main pollutant causing the formation of haze. Based on meteorological parameters, aerosol distribution, and PM monitoring data in Taiyuan during November and December 2016, the characteristics of the key size spectrum of PM_2.5 affecting haze were discussed. During the observation period, haze was frequent and serious. Heavy haze time accounts for 25.35% of the total haze time. Haze events occurred frequently when the relative humidity was greater than 80% and wind speed was less than 1.5 m·s^-1, especially for severe haze. Mild and moderate level haze occurred frequently when the relative humidity was less than 80% and greater than 40% and when wind speed was less than 1.5 m·s^-1. Slight haze mainly occurred when the relative humidity was 20%-40% and the wind speed was 1.25-2.55 m·s^-1. The average mass concentration of PM_2.5 was 209.45 μg·m^-3, which was three times the level during non-haze events. With an increase in the haze level, the mass concentration of PM_2.5 and the ratio of PM_2.5/PM₁₀ increased. PM₁ was the key particle size affecting haze in the low humidity environment. PM_0.5 was the key particle size that affects slight haze, mild haze, and moderate haze in the high humidity environment, while PM₁ was the key particle size that affects heavy haze. The contribution of surface concentration to visibility decreased with high humidity, but the particle size increased by moisture absorption leading to an increase in the extinction efficiency factor, which compensated for the lack of surface concentration. The increase in the particle size parameter was an important factor for PM_2.5 affecting the haze pollution with high humidity.

Effects of air pollution and weather on the initial COVID-19 outbreaks in United States, Italy, Spain, and China: A comparative study

Contrasting effects have been identified in association of weather (temperature and humidity) and pollutant gases with COVID-19 infection, which could be derived from the influence of lockdowns and season change. The influence of pollutant gases and climate during the initial phases of the pandemic, before the closures and the change of season in the northern hemisphere, is unknown. Here, we used a spatial-temporal Bayesian zero-inflated-Poisson model to test for short-term associations of weather and pollutant gases with the relative risk of COVID-19 disease in China (first outbreak) and the countries with more cases during the initial pandemic (the United States, Spain and Italy), considering also the effects of season and lockdown. We found contrasting association between pollutant gases and COVID-19 risk in the United States, Italy, and Spain, while in China it was negatively associated (except for SO₂ ). COVID-19 risk was positively associated with specific humidity in all countries, while temperature presented a negative effect. Our findings showed that short-term associations of air pollutants with COVID-19 infection vary strongly between countries, while generalized effects of temperature (negative) and humidity (positive) with COVID-19 was found. Our results show novel information about the influence of pollution and weather on the initial outbreaks, which contribute to unravel the mechanisms during the beginning of the pandemic.

Raman micro-spectroscopy of two types of acetylated Norway spruce wood at controlled relative humidity

Water is a key element for wood performance, as water molecules interact with the wood structure and affect important material characteristics such as mechanical properties and durability. Understanding wood-water interactions is consequently essential for all applications of wood, including the design of wood materials with improved durability by chemical modification. In this work, we used Raman micro-spectroscopy in combination with a specially designed moisture chamber to map molecular groups in wood cell walls under controlled moisture conditions in the hygroscopic range. We analyzed both untreated and chemically modified (acetylated to achieve two different spatial distributions of acetyl groups within the cell wall) Norway spruce wood. By moisture conditioning the specimens successively to 5, 50, and 95% relative humidity using deuterium oxide (D₂O), we localized the moisture in the cell walls as well as distinguished between hydroxyl groups accessible and inaccessible to water. The combination of Raman micro-spectroscopy with a moisturizing system with deuterium oxide allowed unprecedented mapping of wood-water interactions. The results confirm lower moisture uptake in acetylated samples, and furthermore showed that the location of moisture within the cell wall of acetylated wood is linked to the regions where acetylation is less pronounced. The study demonstrates the local effect that targeted acetylation has on moisture uptake in wood cell walls, and introduces a novel experimental set-up for simultaneously exploring sub-micron level wood chemistry and moisture in wood under hygroscopic conditions.

Aerial roots elevate indoor plant health: Physiological and morphological responses of three high-humidity adapted Araceae species to indoor humidity levels

Heightened by the COVID-19 pandemic there has been a global increase in urban greenspace appreciation. Indoor plants are equally important for improving mental health and air quality but despite evolving in humid (sub)tropical environments with aerial root types, planting systems ignore aerial resource supply. This study directly compared nutrient uptake preferences of aerial and soil-formed roots of three common houseplant species under high and ambient relative humidities. Growth and physiology parameters were measured weekly for Anthurium andreanum, Epipremnum aureum and Philodendron scandens grown in custom made growth chambers. Both aerial and soil-formed roots were then fed mixtures of nitrate, ammonium and glycine, with one source labelled with ¹⁵ N to determine uptake rates and maximum capacities. Aerial roots were consistently better at nitrogen uptake than soil roots but no species, root type or humidity condition showed a preference for a particular nitrogen source. All three species grew more in high humidity, with aerial roots demonstrating the greatest biomass increase. Higher humidities for indoor niches, together with fertiliser applications to aerial roots will support indoor plant growth, creating lush calming indoor environments for people inhabitants.

SAW Humidity Sensing with rr-P3HT Polymer Films

In the present paper the humidity sensing properties of regioregular rr-P3HT (poly-3-hexylthiophene) polymer films is investigated by means of surface acoustic wave (SAW) based sensors implemented on LiNbO3 (1280 Y-X) and ST-quartz piezoelectric substrates. The polymeric layers were deposited along the SAW propagation path by spray coating method and the layers thickness was measured by atomic force microscopy (AFM) technique. The response of the SAW devices to relative humidity (rh) changes in the range ~5-60% has been investigated by measuring the SAW phase and frequency changes induced by the (rh) absorption in the rr-P3HT layer. The SAW sensor implemented onto LiNbO3 showed improved performance as the thickness of the membrane increases (from 40 to 240 nm): for 240 nm thick polymeric membrane a phase shift of about -1.2 deg and -8.2 deg was measured for the fundamental (~78 MHz operating frequency) and 3rd (~234 MHz) harmonic wave at (rh) = 60%. A thick rr-P3HT film (~600 nm) was deposited onto the quartz-based SAW sensor: the sensor showed a linear frequency shift of ~-20.5 Hz per unit (rh) changes in the ~5-~50% rh range, and a quite fast response (~5 s) even at low humidity level (~5% rh). The LiNbO3 and quartz-based sensors response was assessed by using a dual delay line system to reduce unwanted common mode signals. The simple and cheap spray coating technology for the rr-P3HT polymer films deposition, complemented with fast low level humidity detection of the tested SAW sensors (much faster than the commercially available Michell SF-52 device), highlight their potential in a low-medium range humidity sensing application.

Identification of Damping of Spruce Wood (Picea abies) under Various Levels of Moisture Content Using Time-Scale Decomposition

The damping of spruce wood is analysed at different moisture content levels for the first three vibration modes of tangentially and radially vibrating samples. Two methods were used to determine the damping. The first was the vibration envelope fitting as an improved version of the well-known logarithmic decrement, and the second was the newer and recently increasingly used wavelet transform. Both methods showed that the damping of spruce wood first decreases and then increases with moisture content, with the damping in the first vibration mode being about 9% higher in the radial direction than in the tangential direction. In the second and third vibration modes, the damping in the tangential direction was higher than in the radial direction by about 10% and 8.8%, respectively. The measured damping factors from the envelope fitting had, on average, 15.9% higher values than those from the wavelet transform. It can be concluded from the results that the wavelet transform is more accurate for determining the damping factor, as it enables the decoupling of multi-degree of freedom systems if mode coupling is present.

Relative contributions of selected multigeneration products to chamber SOA formed from photooxidation of a range (C10-C17) of n-alkanes under high NO x conditions

A series of chamber experiments was conducted to investigate the composition of secondary organic aerosol (SOA) following oxidation of a range of parent n-alkanes (C10-C17) in the presence of NO x . The relative contribution of selected species representing first, second, and higher generation products to SOA mass was measured using a high-resolution aerosol mass spectrometer. Gas chromatography was also used for a limited set of amenable species. Relative contributions varied substantially across the range of investigated alkanes reflecting slight changes in SOA composition. The contribution of first-generation cyclic hemiacetal is minimal toward the small end of the investigated range and gradually increase with n-alkane size. The relative contribution of second generation and higher nitrate-containing species, in contrast, decrease with an increased alkane size. A similar trend is observed for relative contribution of organonitrates to SOA. Finally, SOA yield and composition are sensitive to water vapor concentrations. This sensitivity is limited to a narrow range (dry to ~15% RH) with little, if any, impact above 15% suggesting that this impact may be negligible under ambient conditions. The impact of water vapor also appears to decrease with increasing alkane carbon number.

The Effect of Relative Humidity on Creep Behavior of Cement Paste Microprism

Despite decades of extensive studies, the mechanism of concrete creep remains a subject of debate, mainly due to the complex nature of cement microstructure. This complexity is further amplified by the interplay between water and the cement microstructure. The present study aimed to better understand the creep mechanism through creep tests on microprisms of cement paste at hygral equilibrium. First, microprisms with dimensions of 150 mm × 150 mm × 300 mm were prepared by precision cutting from a cement paste specimen with a water-to-cement ratio of 0.4. Subsequently, uniaxial compression and creep tests were carried out on these microprisms in a chamber with controlled relative humidity (RH). To mitigate the impact of plasticity and damage, the applied peak load was set to generate a stress level that was approximately 40% of the compressive strength. Moreover, an analytical coefficient φ was formulated to account for the foundation effect on microprism creep, agreeing with the numerical analysis employing the finite element method. Our findings showed that the microscale creep compliance varied when the RH level was changed from 90% to 11%. Furthermore, logarithmic and power-law models were both applied to simulate creep curves. Lastly, the modeled creep behaviors were compared with those obtained by microindentation experiments in previous studies.

Assay system for mesocotyl elongation and hydrotropism of maize primary root in response to low moisture gradient

We designed and validated a test system that simulates a growth environment for Zea mays L. maize seedlings under conditions of low moisture gradient in darkness. This system allowed us to simultaneously measure mesocotyl elongation and the primary root hydrotropic response in seedlings before the emergence phase in a collection of maize hybrids. We found great variation in these two traits with statistically significant reduction of their elongations under the low moisture gradient condition that indicate the richness of maize genetic diversity. Hence, the objective of designing a new test system that evaluates the association between these underground traits with the potential use to measure other traits in maize seedlings related to early vigor was achieved.

Association of temperature and relative humidity with the growth rate of the coronavirus disease 2019 epidemic

The effects of temperature and relative humidity on the growth of coronavirus disease 2019 (COVID-19) remain unclear. Data on the COVID-19 epidemic that were analyzed in this study were obtained from the official websites of the National Health Commission of China and the Health Commissions of 31 provinces in China. From January 26 to February 25, 2020, the cumulative number of confirmed COVID-19 cases in each region was counted daily using data from our database. Curve fitting of daily scatter plots of the relationship between epidemic growth rate (GR) with average temperature (AT) and average relative humidity (ARH) was conducted using the loess method. The heterogeneity across days and provinces was calculated to assess the necessity of using a longitudinal model. Fixed-effect models with polynomial terms were developed to quantify the relationship between variations in the GR and AT or ARH. An increased AT markedly reduced the GR when the AT was lower than -5°C, the GR was moderately reduced when the AT ranged from -5°C to 15°C, and the GR increased when the AT exceeded 15°C. ARH increased the GR when it was less than 72% and reduced the GR when it exceeded 72%. The temperature and relative humidity curves were not linearly associated with the GR of COVID-19. The GR was moderately reduced when the AT ranged from -5°C to 15°C. When the AT was lower or higher than -5°C to 15°C, the GR of COVID-19 increased. An increased ARH increased the GR when the ARH was lower than 72% and reduced the GR when the ARH exceeded 72%.

Management and Mitigation of Temperature and Humidity Events in the Perioperative Setting

Temperature or relative humidity variations that fall outside the recommended parameters for the perioperative environment can have serious implications for patient safety and satisfaction as well as business continuity. Some pathogenic microbes can thrive in prolonged elevated humidity. Supplies and equipment in perioperative environments exposed to variations in temperature and humidity may become sources of infection or undergo alterations in function, putting patients at increased risk of harm. Other negative effects include increased costs, legal liability, and decreased patient satisfaction stemming from delays or rescheduled procedures. This article includes two hypothetical scenarios in which facility personnel respond to a condensation event and a fluid leak to avoid substantial negative effects in perioperative services. Also discussed is the role perioperative staff members play in preventing adverse consequences through rapid identification of temperature and humidity variations and early intervention. Finally, the existing guidelines on perioperative temperature and humidity and multidisciplinary risk assessments and recommendations for education, prevention, and risk mitigation are explored.

[Effects of urban wetlands with different shapes on the temperature and humidity of ambient environment.]

To quantify the effects of urban wetlands on temperature and humidity of ambient environment, five urban wetlands with different shapes and surroundings were selected in Daqing City, and the air temperature and relative humidity were investigated in spring, summer and autumn using small-scale quantitative measurement method. The results indicated that the urban wetlands with different shapes all could decrease the temperature and increase the humidity, with the effect being strongest in summer, followed by in spring, and the smallest effect in autumn. The shape of the urban wetland had significant effect on temperature and humidity, which decreased in the order of irregular-shaped wetland > regular-shaped wetland (subcircular-shaped wetland, subcuboid-shaped wetland) > long-shaped wetland. The diurnal variation of temperature and humidity was influenced by the ambient temperature, namely the effect of wetlands was weak in morning and evening, but strong at noon. The maximum effect occurred at12:00-14:00 in spring and autumn, and at 14:00-16:00 in summer.

[Pollution Characteristics of Aerosol Number Concentration in Winter and Spring in a Northern Suburb of Nanjing]

Using APS-3321, the atmospheric aerosol number concentrations (0.5-20 μm) were continuously monitored to analyze the characteristics of winter and spring pollution in 2014 in a northern suburb of Nanjing. The average number concentrations were (364.8±297.8) cm^-3 and (79.6±62.4) cm^-3 in winter and spring, respectively; fine particles (0.5-1.0 μm) accounted for 87.8% and 86.6% of the total, respectively. There were significant variations in number concentration at different periods. The diurnal variations in number concentrations were evident with high concentrations at night and low concentrations during the day. The early peaks were at 07:00 and 09:00, and number concentrations began to increase rapidly starting at 17:00 and 18:00 in winter and spring, respectively. The distribution of the number concentrations was unimodal, with peak sizes between 0.583 and 0.626 μm in winter and less than 0.542 μm in spring. With the increase in relative humidity, aerosol number concentrations increased gradually; at the same time, the peak size moved to a larger diameter which reflected the influence of hygroscopic growth of aerosols. During the total observation period, it reached 83.3% of the proportion of hazy days. The number concentration of particles less than 2.0 μm increased significantly with the increase in the haze pollution level, which was more obvious in winter. In spring, the proportion of fine particles increased with the increase in the haze level but in winter, it decreased during hazy days due to a significant increase in particle size caused by aging. The analysis of the typical pollution process in January indicated that there was a strong correlation between the source of air mass and the surface wind direction. Pollutants transmitted from the northern Jiangsu Province and the accumulation of pollutants due to slow winds were important causations of the pollution process.

Severe acute respiratory syndrome coronavirus-2 medical solid waste treatment: A need for efficient and effective strategies in low-resourced settings

Understanding infections related to handling healthcare waste products is of critical importance and the application of simple and low-cost strategies remain a priority in low-income and middle-income countries to protect healthcare workers. We examined the potential effect of relative humidity (RH), air temperature and ultraviolet irradiation (UI) to establish an efficient and effective way to facilitate disposal of medical waste. Literature is emerging on the effect of high RH and high temperature, which would increase airborne mass deposition and decrease the viability of viruses in both airborne particles and on surfaces. On the other hand, severe acute respiratory syndrome coronavirus-2 has been proven to be susceptible to UI when suspended in air like other coronaviruses. An innovative approach utilizing environmental conditions might represent an effective and efficient way to ensure better and sustainable protection of the healthcare workers in low-resourced settings.

Influence of Humidity and Heating Rate on the Continuous ZIF Coating during Hydrothermal Growth

Zeolitic imidazolate frameworks (ZIFs) have potential for various gas and ion separations due to their well-defined pore structure and relatively easy fabrication process compared to other metal-organic frameworks and zeolites. As a result, many reports have focused on preparing polycrystalline and continuous ZIF layers on porous supports with good separation performance in various target gases, such as hydrogen extraction and propane/propylene separation. To utilize the separation properties in industry, membrane is required to be prepared in large scale with high reproducibility. In this study, we investigated how humidity and chamber temperature influence the structure of a ZIF-8 layer prepared by the hydrothermal method. Many synthesis conditions can affect the morphology of polycrystalline ZIF membranes, and previous studies have mainly focused on reaction solutions, such as precursor molar ratio, concentration, temperature, and growth time. On the other hand, we found that the humidity of the chamber and the heating rate of the solution also lead to dramatic changes in the morphology of ZIF membranes. To analyze the trend between humidity and chamber temperature, we set up the chamber temperature (ranging from 50 °C to 70 °C) and relative humidity (ranging from 20% to 100%) using a thermo-hygrostat chamber. We found that as the chamber temperature increased, ZIF-8 preferentially grew into particles rather than forming a continuous polycrystalline layer. By measuring the temperature of the reacting solution based on chamber humidity, we discovered that the heating rate of the reacting solution varied with humidity, even at the same chamber temperature. At a higher humidity, the thermal energy transfer was accelerated as the water vapor delivered more energy to the reacting solution. Therefore, a continuous ZIF-8 layer could be formed more easily at low humidity ranges (ranging from 20% to 40%), while micron ZIF-8 particles were synthesized at a high heating rate. Similarly, under higher temperatures (above 50 °C), the thermal energy transfer was increased, leading to sporadic crystal growth. The observed results were obtained with a controlled molar ratio, in which zinc nitrate hexahydrate and 2-MIM were dissolved in DI water at a molar ratio of 1:45. While the results are limited to these specific growth conditions, our study suggests that controlling the heating rate of the reaction solution is critical for preparing a continuous and large-area ZIF-8 layer, particularly for the future scale-up of ZIF-8 membranes. Additionally, humidity is an important factor in forming the ZIF-8 layer, as the heating rate of the reaction solution can vary even at the same chamber temperature. Further research related to humidity will be necessary for the development of large-area ZIF-8 membranes.