Water Vapor Pressure Research Articles

Critical Analysis of Published Physical Property Data for Aqueous Potassium Hydroxide. Collation into Detailed Models for Alkaline Electrolysis

Physical properties of aqueous KOH solutions are crucial to the design and operation of alkaline electrolyzers but have been scarcely and sometimes unreliably reported. Obtaining published data for various properties currently requires time-consuming searches and subsequent interpretation, interpolation, and extrapolation. This work collates and critically analyzes published data for a range of physical properties relevant to alkaline electrolysis, including the density, viscosity, conductivity, surface tension, oxygen/hydrogen solubility, oxygen/hydrogen diffusivity, and water vapor pressures of aqueous KOH solutions, as a function of temperature, KOH molarity, and pressure. Correlation functions, in the form of excel spreadsheets, have been developed to allow interpolation of the most reliable data and computation of desired quantities at specific temperatures, pressures, and KOH concentrations. Composite models incorporating these properties have been developed for automated computation of (i) diffusive gas crossover and (ii) gas production volumes, including (iii) water vapor content, and associated (iv) dissolved gas concentrations in the liquid electrolyte, as a function of KOH concentration, temperature, pressure, current density, and separator thickness and porosity. These spreadsheets are provided in the Supporting Information, as tools and reference points for researchers and practitioners in alkaline electrolysis.

Onset of cardiovascular drift during progressive heat stress in young adults (PSU HEAT project).

With climate change, humans are at a greater risk for heat-related morbidity and mortality, often secondary to increased cardiovascular strain associated with an elevated core temperature (Tc). Critical environmental limits (i.e., the upper limits of compensable heat stress) have been established based on Tc responses for healthy, young individuals. However, specific environmental limits for the maintenance of cardiovascular homeostasis have not been investigated in the context of thermal strain during light activity. Therefore, the purposes of this study were to 1) identify the specific environmental conditions (combinations of ambient temperature and water vapor pressure) at which cardiovascular drift [i.e., a continuous rise in heart rate (HR)] began to occur and 2) compare those environments to the environmental limits for the maintenance of heat balance. Fifty-one subjects (27 F; 23 ± 4 yr) were exposed to progressive heat stress across a wide range of environmental conditions in an environmental chamber at two low metabolic rates reflecting minimal activity (MinAct; 159 ± 34 W) or light ambulation (LightAmb; 260 ± 55 W). Whether systematically increasing ambient temperature or humidity, the onset of cardiovascular drift occurred at lower environmental conditions compared with Tc inflection points at both intensities (P < 0.05). Furthermore, the time at which cardiovascular drift began preceded the time of Tc inflection (MinAct P = 0.01; LightAmb P = 0.0002), and the difference in time between HR and Tc inflection points did not differ (MinAct P = 0.08; LightAmb P = 0.06) across environmental conditions for either exercise intensity. These data suggest that even in young adults, increases in cardiovascular strain precede the point at which heat stress becomes uncompensable during light activity.NEW & NOTEWORTHY To our knowledge, this study is the first to 1) identify the specific combinations of temperature and humidity at which an increase in cardiovascular strain (cardiovascular drift) occurs and 2) compare those environments to the critical environmental limits for the maintenance of heat balance. We additionally examined the difference in time between the onset of increased cardiovascular strain and uncompensable heat stress. We show that an increase in cardiovascular strain systematically precedes sustained heat storage in young adults.

Variation characteristics of Poyang Lake water area and its response to meteorological factors in the past 35 years

Abstract The hydrological situation of Poyang Lake has undergone changes due to the influence of climate change and human activities. Its typical throughput and seasonal variation characteristics have attracted much attention. Research on the long-term hydrological variation of Poyang Lake needs to be enriched. Using remote sensing images from 1986 to 2020 and combining them with the Normalized Difference Vegetation Index (NDVI), this study extracts the water area of Poyang Lake and analyzes its variation characteristics. The results show that the water area of Poyang Lake has a consistent periodic variation with meteorological factors. Both the water area and meteorological factors have a main period of 18 m (months). Water area change points occurred in 2003, 2010, and 2016. In different research periods, there is a significant correlation between the water area and meteorological factor changes. Furthermore, the correlation between water vapor pressure and precipitation with the water area change is the strongest.

A dataset of carbon dioxide flux observation of the &amp;lt;italic&amp;gt;Miscanthus sacchariflorus&amp;lt;/italic&amp;gt; ecosystem of Dongting Lake Wetland from 2014 to 2016

With considerable carbon sequestration potential, lakes are active channels of terrestrial carbon cycle. As the second largest freshwater lake in China, Dongting Lake has huge annual water level fluctuations (12–14 m), and the unique hydrological situation is a major challenge and of significance to the study of the carbon and water cycle processes at Dongting Lake, the control mechanism and its response to environmental changes. Miscanthus sacchariflorus is widely distributed at Dongting Lake and is a perennial tall bamboo-like herb with well-developed rhizomes and high carbon sequestration potential. Targeting the Miscanthus sacchariflorus ecosystem of Dongting Lake as the research object, we used the eddy-correlation (EC) system in the study to conduct long-term localized observations of carbon fluxes in the Miscanthus sacchariflorus ecosystem. As the first Dongting Lake ecosystem research station in China, National Field Scientific Observation and Research Station of Dongting Lake Wetland Ecosystem in Hunan Province (Dongting Lake National Station) collated the fluxes and conventional meteorological data of the Dongting Lake Miscanthus sacchariflorus ecosystem from June 2014 to December 2016 based on the data processing system of the China Flux Observation and Research Network (ChinaFLUX). The dataset includes the data files of net ecosystem carbon exchange, ecosystem respiration, ecosystem carbon exchange, latent heat flux, sensible heat flux, air temperature, relative air humidity, water vapor pressure, net radiation, and soil temperature at half-hourly, daily, monthly, and yearly scales. It can provide a strong data base for scientific understanding of the spatial and temporal dynamics of carbon, water and heat in the Miscanthus sacchariflorus ecosystem, material and energy cycles, estimation of global carbon sequestration potential, as well as response and adaptation to global climate change.

Osmotic Coefficients of Gabapentin Drug in Aqueous Solutions of Deep Eutectic Solvents: Experimental Measurements and Thermodynamic Modeling

Most of the applications for aqueous deep eutectic solvent (DES) solutions are directly related to molecular interactions, which can be studied using thermodynamic properties. In this regard, the activity coefficient and osmotic coefficient studies have provided evidence for understanding the depth of ion pair formation, ion solvent, and ion–ion interactions in solutions. In this study, the osmotic coefficients for binary gabapentin (GBP)/water and ternary GBP/DES (ChCl/EG and ChCl/U) aqueous solutions were calculated using vapor pressure osmometry measurements at T = 298.15 K and pressure 872 hPa. Water activities, osmotic coefficients, and vapor pressure depressions were all calculated for binary solutions. The Pitzer equation was used to correlate the osmotic coefficient values. Activity coefficients for GBP in the binary systems were determined by the obtained parameters of this equation. The standard deviation for the osmotic coefficient value in the binary system with the Pitzer equation is 0.0059. In ternary solutions, two different DES concentrations (about molality 1 and 3) were used to investigate the effect of concentration on osmotic coefficients. For ternary solutions, it was also possible to obtain quantities like water activity and osmotic coefficient data. Finally, the predicted values of water activity using the Lin and ECA models were applied to compare the results of water activity in the studied systems. The results showed that the ECA and Lin models have 0.00045 and 0.0011 average standard deviation, respectively.

The effect of time scales on the distribution of evapotranspiration and driving factors in desert grasslands

Promoting the reasonable allocation of evaporation (E) and transpiration (T) at a certain time scale is important for controlling the grassland desertification. Nevertheless, evapotranspiration (ET) and its components on a single time scale often cannot guarantee the dynamic and reasonable distribution of E and T. This study quantified ET and its component distribution in different time scales of the plant-growing season in desert grassland ecosystems to address this contradiction. Further the main driving factors of ET and its components at different time scales were clarified under multi-factor coupling. Results indicated that E was the leading component of ET in the ecosystem, with an average T/ET of 39.64%. The dominant factors of T/ET on different time scales were air temperature (Ta) and surface temperature (Ts), which showed significant negative correlations (p < 0.05). ET and its components showed obvious unimodal changes at the hourly scale. The peaks occurred at 12:00–14:00, and they all increased with increasing radiation (Ra), Ts, Ta, and saturated water vapor pressure difference (VPD). Ta was the dominant factor with a correlation coefficient of 0.76, followed by VPD> Ra>Ts. At the daily scale, ET and its components showed clear seasonal changes, ET was 1.94 mm d-1and T was 0.77 mm d-1. The dominant factors were soil moisture content (SWC) of the 0–10 cm soil layer and Ts. The dominant factors affecting ET and its components in the early, middle, and late stages of growth were relative humidity (RH), SWC, and Ts. At the monthly scale, the cumulative values of ET and its components were the largest in August and the lowest in October, mainly regulated by precipitation (P), whereas, T/ET had no significant correlation with P. The results from this study can provide a scientific basis for vegetation restoration and environmental protection in desert grassland ecological function areas.

Temperature-Humidity-Dependent Wind Effects on Physiological Heat Strain of Moderately Exercising Individuals Reproduced by the Universal Thermal Climate Index (UTCI).

Increasing wind speed alleviates physiological heat strain; however, health policies have advised against using ventilators or fans under heat wave conditions with air temperatures above the typical skin temperature of 35 °C. Recent research, mostly with sedentary participants, suggests mitigating the effects of wind at even higher temperatures, depending on the humidity level. Our study aimed at exploring and quantifying whether such results are transferable to moderate exercise levels, and whether the Universal Thermal Climate Index (UTCI) reproduces those effects. We measured heart rates, core and skin temperatures, and sweat rates in 198 laboratory experiments completed by five young, semi-nude, heat-acclimated, moderately exercising males walking the treadmill at 4 km/h on the level for three hours under widely varying temperature-humidity combinations and two wind conditions. We quantified the cooling effect of increasing the wind speed from 0.3 to 2 m/s by fitting generalized additive models predicting the physiological heat stress responses depending on ambient temperature, humidity, and wind speed. We then compared the observed wind effects to the assessment performed by the UTCI. Increasing the wind speed lowered the physiological heat strain for air temperatures below 35 °C, but also for higher temperatures with humidity levels above 2 kPa water vapor pressure concerning heart rate and core temperature, and 3 kPa concerning skin temperature and sweat rate, respectively. The UTCI assessment of wind effects correlated positively with the observed changes in physiological responses, showing the closest agreement (r = 0.9) for skin temperature and sweat rate, where wind is known for elevating the relevant convective and evaporative heat transfer. These results demonstrate the potential of the UTCI for adequately assessing sustainable strategies for heat stress mitigation involving fans or ventilators, depending on temperature and humidity, for moderately exercising individuals.

Elucidating the Mechanism of Self-Healing in Hydrogel-Lead Halide Perovskite Composites for Use in Photovoltaic Devices.

Since the emergence of organometal halide perovskite (OMP) solar cells, there has been growing interest in the benefits of incorporating polymer additives into the perovskite precursor, in terms of both photovoltaic device performance and perovskite stability. In addition, there is interest in the self-healing properties of polymer-incorporated OMPs, but the mechanisms behind these enhanced characteristics are still not fully understood. Here, we study the role of poly(2-hydroxyethyl methacrylate) (pHEMA) in improving the stability of methylammonium lead iodide (MAPI, CH3NH3PbI3) and determine a mechanism for the self-healing of the perovskite-polymer composite following exposure to atmospheres of differing relative humidity, using photoelectron spectroscopy. Varying concentrations of pHEMA (0-10 wt %) are incorporated into a PbI2 precursor solution during the conventional two-step fabrication method for producing MAPI. It is shown that the introduction of pHEMA results in high-quality MAPI films with increased grain size and reduced PbI2 concentration compared with pure MAPI films. Devices based on pHEMA-MAPI composites exhibit an improved photoelectric conversion efficiency of 17.8%, compared with 16.5% for a pure MAPI device. pHEMA-incorporated devices are found to retain 95.4% of the best efficiency after ageing for 1500 h in 35% RH, compared with 68.5% achieved from the pure MAPI device. The thermal and moisture tolerance of the resulting films is investigated using X-ray diffraction, in situ X-ray photoelectron spectroscopy (XPS), and hard XPS (HAXPES). It is found that exposing the pHEMA films to cycles of 70 and 20% relative humidity leads to a reversible degradation, via a self-healing process. Angle-resolved HAXPES depth-profiling using a non-destructive Ga Kα source shows that pHEMA is predominantly present at the surface with an effective thickness of ca. 3 nm. It is shown using XPS that this effective thickness reduces with increasing temperature. It is found that N is trapped in this surface layer of pHEMA, suggesting that N-containing moieties, produced during reaction with water at high humidity, are trapped in the pHEMA film and can be reincorporated into the perovskite when the humidity is reduced. XPS results also show that the inclusion of pHEMA enhances the thermal stability of MAPI under both UHV and 9 mbar water vapor pressure.

Minimizing Area-Specific Resistance of Electrochemical Hydrogen Compressor under Various Operating Conditions Using Unsteady 3D Single-Channel Model.

Extensive research has been conducted over the past few decades on carbon-free hydrogen energy. Hydrogen, being an abundant energy source, requires high-pressure compression for storage and transportation due to its low volumetric density. Mechanical and electrochemical compression are two common methods used to compress hydrogen under high pressure. Mechanical compressors can potentially cause contamination due to the lubricating oil when compressing hydrogen, whereas electrochemical hydrogen compressors (EHCs) can produce high-purity, high-pressure hydrogen without any moving parts. A study was conducted using a 3D single-channel EHC model focusing on the water content and area-specific resistance of the membrane under various temperature, relative humidity, and gas diffusion layer (GDL) porosity conditions. Numerical analysis demonstrated that the higher the operating temperature, the higher the water content in the membrane. This is because the saturation vapor pressure increases with higher temperatures. When dry hydrogen is supplied to a sufficiently humidified membrane, the actual water vapor pressure decreases, leading to an increase in the membrane's area-specific resistance. Furthermore, with a low GDL porosity, the viscous resistance increases, hindering the smooth supply of humidified hydrogen to the membrane. Through a transient analysis of an EHC, favorable operating conditions for rapidly hydrating membranes were identified.

Evaluation of Hydrogen Ions Flowing through Protonic Ceramic Fuel Cell Using Ytterbium-Doped Barium Zirconate as Electrolyte

To measure the proton current in a PCFC (protonic ceramic fuel cell), the proton current detector was developed using a proton conducting oxide. The amount of proton current that flowed in the PCFC can be measured by an apparatus developed based on the electromotive force of an electrochemical cell using 10 mol% In-doped CaZrO3 (hydrogen sensor) and Y-stabilized zirconia (oxygen sensor). The water vapor pressure on the cathode changed when hydrogen ions pass through the PCFC. The hydrogen ion current can be determined by monitoring the water vapor pressure. The electronic leakage was then estimated from the hydrogen ion current and external current. We measured the current of hydrogen flowing through protonic ceramic fuel cell using ytterbium-doped barium zirconate as the electrolyte. Hydrogen ions and holes were found to leak under the OCV at 700°C. The electronic leakage was found to be suppressed with the increasing electrolyte film thickness. On the other hand, no leakage of hydrogen and holes was observed at 500°C.

Estimation of the Daily Production Levels of a Run-of-River Hydropower Plant Using the Artificial Neural Network

Renewable energy sources, as well as the studies being conducted regarding these energy sources, are becoming increasingly important for our world. In this manuscript, the daily energy production level of a small (15 MW) run-of-river hydropower plant (RRHPP) was estimated using the artificial neural network (ANN) model. In this context, the model utilized both meteorological data and HPP-related data. The input parameters of the artificial neural network included the daily total precipitation, daily mean temperature, daily mean water vapour pressure, daily mean relative humidity, and the daily mean river water elevation at the hydropower plant, while the only output parameter consisted of the total daily energy production. For the ANN, data from the four years between 2017 and 2020 were used for training purposes, while data from the first eight months of 2021 were used for testing purposes. Ten different ANN networks were tested. A comparison of the ANN data with the real data indicated that the model provided satisfying results. The minimum error rate was 0.13%, the maximum error rate was 9.13%, and the mean error rate was 3.13%. Furthermore, six different algorithms were compared with each other. It was observed that the best results were obtained from the Levenberg-Marquardt algorithm.This study demonstrated that the ANN can estimate the daily energy production of a run-of-river HPP with high accuracy and that this model can potentially contribute to studies investigating the potential of renewable energies.

Feasibility and adaptability investigation on wet hydrogen dehumidification using vortex tube

This paper aims at exploring the feasibility of removing water vapour from wet hydrogen by vortex tube. For this purpose, a numerical model is developed for wet hydrogen condensing flow by adding two transport equations. Three different operating parameters, cold mass fraction, inlet pressure and molar fraction of water vapour, are discussed in terms of the impact on the flow and condensation process. The results show that the increase of the inlet pressure and the cold mass fraction can provide a favourable condensation environment for water vapour, which resulting in the increase of the number of droplets and mass fraction of the liquid. Condensation process is aggravated with high molar fraction of water vapour at inlet, although there is no significant change in pressure and temperature fields. Furthermore, a comprehensive study is performed by analysing the dehumidification performance and entropy generation. The maximum value of dehumidification performance up to 83.12% while cold mass fraction is 0.8218 and inlet pressure is 5 bar, which shows a good feasibility for wet hydrogen dehumidification.

Saturation Vapor Pressure of Water over Sodium Borohydride Dihydrate

Saturation Vapor Pressure of Water over Sodium Borohydride Dihydrate

Electrical properties of BaZr0.5Ce0.3Y0.1Yb0.1O3-δ proton conductor for reversible proton-conducting solid oxide electrochemical cells

Proton-conducting oxide-based reversible solid oxide electrochemical cells (protonic-SOEC, P-SOEC) have a great potential to be the most efficient transition technology operating at intermediate temperatures. Here, we have introduced a perovskite-type proton conductor BaZr0.5Ce0.3Y0.1Yb0.1O3-δ (BZCYYb5311) and evaluated its electrochemical and transport properties. The chemical stability of BZCYYb5311 was confirmed by thermo-gravimetric analysis (TGA) under pure CO2 conditions and X-ray diffraction analysis. The total and partial conductivities were obtained using DC four-probe conductivity measurements under various pO2 and pH2O conditions. The ratio of proton conductivity to ionic conductivity including the oxygen-ion conductivity of this material was 98% at 600 °C, indicating that it is a relatively pure proton conductor with most of the ionic conduction almost exclusively carried out by protons. Chemical diffusivities were calculated from Fick's 2nd law by non-linear least squares fitting during oxidation/reduction and hydration/dehydration processes and were faster than other proton conductor BZCY (Y-doped BaCeO3-BaZrO3) series, which have a similar zirconium contents. In addition, the theoretical performance and efficiency of the reversible P-SOEC were determined from the spatial distribution of oxygen and hydrogen partial pressure in BZCYYb5311, calculating the maximum power density (4.5 Wcm−2 at 600 °C, 3% of water vapor pressure) for the fuel cell mode and current density (12.3 Acm−2 at 1.5 V, 600 °C, and 20% of water vapor pressure) for the electrolysis mode. The fuel consumption efficiency is high (99.1% at 0.6 V at 600 °C), while the electrolysis efficiency is low (72.3% at 1.6 V) due to the dominant p-type regime in the electrolyte during electrolysis. This low electrolysis efficiency can be enhanced by recovering the electrolyte regime by increasing pH2O or decreasing pO2 in the air electrode; however, it will still have low efficiency. Consequently, BZCYYb5311 is not an efficient electrolyte material for electrolyzers, but is promising for fuel cells because of its superior chemical stability, exceptional pure proton conductivity, and better bulk diffusion than those of the BZCY system.

Relative influence of individual characteristics on critical WBGT limits in young adults (PSU HEAT Project)

Critical environmental limits are temperature-humidity thresholds above which heat balance cannot be maintained for a given metabolic heat production. This study examined the association between individual characteristics [sex, body surface area (A D ), aerobic capacity (V̇O 2max ; L∙min-1), and body mass (m b )] and critical environmental limits in young adults. Forty-four (20 M/24 F; 23±4 yr) subjects were exposed to progressive heat stress in an environmental chamber at two low net metabolic rates (M net ); minimal activity (MinAct; M net = 160±35 W) and light ambulation (LightAmb; M net = 259±54 W). In 2 hot-dry (HD; &lt;25% rh) environments, ambient water vapor pressure (P a = 12 or 16 mmHg) was held constant and dry-bulb temperature (T db ) was systematically increased. In 2 warm-humid (WH; &gt;50% rh) environments, T db was held constant at 34 or 36 °C and P a was systematically increased. The critical wet-bulb globe temperature (WBGT crit ) was determined for each condition. There were no sex differences in WBGT crit for any condition ( p ≥ 0.21). During MinAct, only m b was retained in a backward linear regression model explaining the variance in WBGT crit in WH (R 2adj = 0.08, p &lt; 0.001), whereas m b and V̇O 2max were retained for HD environments (R 2adj = 0.09, p &lt; 0.001). During LightAmb, m b and A D were retained in the model for both WH (R 2adj = 0.46, p &lt; 0.001) and HD environments (R 2adj = 0.22; p &lt; 0.001). These data demonstrate the relative importance of individual characteristics on WBGTcrit during low-intensity weight-bearing (LightAmb) and non-weight-bearing (MinAct) activity in extreme thermal environments. This work was supported by NIH R01 AG067471. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Secular changes (1826–2021) of human thermal stress according to UTCI in Kraków (southern Poland)

AbstractThe set of meteorological data from the Jagiellonian University station in Kraków is one of the longest‐recorded in central Europe. Measurement records date back to 1826. Based on the average monthly values of air temperature, total cloudiness, water vapour pressure and wind speed at 1200 UTC, the UTCI values were calculated and the occurrence of cold stress (UTCI &lt; −13°C) and heat stress (UTCI &gt; 32°C) was estimated. The variability of the applied measures of thermal stress conditions was studied both annually and in individual seasons (MAM, JJA, SON, DJF). Statistically significant changes in the studied characteristics of the bioclimate were found. Average annual UTCI values increased at the rate of 0.27°C/10 years. In individual seasons, the trend of UTCI changes ranged from 0.10°C/10 years in summer to 0.43°C/10 years in winter. The number of days with cold stress decreased by 1.8 days/10 years and the number of days with heat stress significantly increased (0.5 days/10 years). Two subperiods with different trends of changes were determined. The first covers the years 1826–1940, and the second, 1941–2021. The former indicates a negative UTCI trend of −0.17°C/10 years, and the latter, an increasing trend of 1.09°C/10 years. The last eight decades have brought a decrease in cold days of 6.5/10 years and an increase in heat days of 2.6/10 years.

Comprehensive Effects of Atmosphere and Soil Drying on Stomatal Behavior of Different Plant Types

The soil water supply and atmospheric humidity conditions are crucial in controlling plants’ stomatal behavior and water use efficiency. When there is water stress caused by an increase in saturated water vapor pressure (VPD) and a decrease in soil water content (SWC), plants tend to close stomata to reduce water loss. This affects the gross primary productivity (GPP) and evapotranspiration (ET), subsequently leading to changes in water use efficiency (WUE) and carbon use efficiency (CUE) in plants. However, land–atmosphere interactions mean that water vapor in the atmosphere and soil moisture content causing water stress for plants are closely related. This study aims to compare and estimate the effects of VPD and SWC on the carbon cycle and water cycle for different plant functional types. Based on the fluxnet2015 dataset from around the world, the WUE and CUE of five plant functional types (PFTs) were estimated under varying levels of VPD and SWC. The results showed that high VPD and low SWC limit the stomatal conductance (Gs) and gross primary productivity (GPP) of plants. However, certain types of vegetation (crops, broad-leaved forests) could partially offset the negative effects of high VPD with higher SWC. Notably, higher SWC could even alleviate limitations and partially promote the increase in GPP and net primary production (NPP) with increasing VPD. WUE and CUE were directly affected by Gs and productivity. In general, the increase in VPD in the five PFTs was the dominant factor in changing WUE and CUE. The impact of SWC limitations on CUE was minimal, with an overall impact of only −0.05μmol/μmol on the four PFTs. However, the CUE of savanna plants changed differently from the other four PFTs. The rise in VPD dominated the changes in CUE, and there was an upward trend as SWC declined, indicating that the increase in VPD and decrease in SWC promote the increase in the CUE of savanna plants to some extent.

Interspecific Differences of Stem Diameter Variations in Response to Water Conditions for Six Tree Species in Northeast China

It is important to understand the response of stem diameter variations in dominant tree species to water conditions in Northeast China. The results will provide basic information for scientific predictions of the future development trend of temperate forests in the eastern mountainous area of northeast China. We employed a high-precision dendrometer to continuously monitor the stem radial changes of six dominant tree species in temperate forests in northeast China from 15 April to 24 October in 2021. Precipitation significantly promoted the tree stem diameter increment. The increment of stem diameter in Juglans mandshurica Maxim., Quercus mongolica Fisch. and Betula platyphylla Suk. had a significantly positive correlation with cumulative precipitation. Correlation analysis revealed that the stem radial change (SRC) of six tree species was positively correlated with precipitation (Pre) and relative humidity (RH), and negatively correlated with water vapor pressure deficit (VPD), indicating that the diameter growth of the six tree species was mainly restricted by water conditions. Under drought stress, the stem radial growth rate of the six tree species slowed down, the growth duration decreased and the tree water deficit (TWD) value increased, while there were obvious interspecific differences. Therefore, water conditions limited the stem radial growth of the six tree species, while each tree species had a different response to drought stress.

Environmental drivers of the current and future distribution of high-yielding lacquer trees (Toxicodendron vernicifluum (stokes) F. A. Barkley)

Abstract Lacquer trees (Toxicodendron vernicifluum (Stokes) F.A. Barkley) are an important natural resource with significant economic and cultural value in East Asia. The main product, raw lacquer, is in high demand due to its commercially valuable characteristics. This study analyzed environmental drivers of the current and future distribution of lacquer trees in high-yielding locations using a machine-learning algorithm and Maxent models. Results identified suitable value ranges for four key environmental variables and their relative contribution to environmentally suitable areas (shown as percentages in parentheses): solar radiation, 12 000–13 000 kJ m−2 day−1 (43.1 per cent); min temperature of the coldest month, −3.5 to 3°C (18.7 per cent); annual precipitation, 900–1400 mm (13.9 per cent) and water vapour pressure, 1.2–1.6 KPa (5.1 per cent). Overall, projected climate change until 2100 will reduce the extent of environments suitable for high-yielding lacquer trees in China and the Republic of Korea, although these areas will expand in Japan. In addition to the three East Asian countries in which lacquer trees and production are currently important, the study identified environmentally suitable areas for growing lacquer trees in other countries worldwide under future climate conditions. The study’s methodology, which divided high-yielding records from other occurrence records and modeled them separately, was applicable in analyzing environmental drivers and modelling suitable areas for lacquer trees. This approach may also be beneficial to study the distributions of other plants, especially economically important crops and trees. In future studies, additional data sets capturing anthropogenic drivers and information on single tree level could further improve models exploring the productivity and sustainability of lacquer trees under future climates.

Competitive adsorption and selectivity of water vapor/R134a on activated carbon for indoor air purification

As an efficient tracer gas of activated carbon filter quality testing, the use of R134a is limited by relative humidity (RH) due to water vapor competitive adsorption. To analyze the competitive effect, the isosteric heats between vapor and ASZMT were calculated by C–C equation, the adsorption selectivity was predicted using the DIH method, and the binary adsorption equilibrium of water vapor and R134a on ASZMT were investigated via IAST model. Results showed that water vapor exhibited a higher isosteric heat than R134a at the same adsorption capacity, indicating a stronger interaction with ASZMT. The water vapor/R134a adsorption selectivity on ASZMT increases from 0 to 6.6, proving that the ASZMT is more selective for water vapor than R134a with water vapor pressure increasing. Besides, with water vapor pressure ratio improving, the R134a adsorption capacity on ASZMT decreases obviously, but water vapor adsorption capacity keeps increasing continuously. R134a breakthrough curves (1000 ppm) also showed that with relative humidity increasing, the R134a breakthrough times and dynamic adsorption capacities both became shorter, from 15 min to 9 min and from 6.68 mg/g to 1.49 mg/g, respectively. It proves that R134a and water vapor have obvious competitive adsorption behavior which is mainly dominated by water vapor concentration. It is necessary for ppm-level R134a to control the lower relative humidity of airflow in application.