Water Vapor Pressure Research Articles

Analysis of drought response thresholds and drought-causing factors of central Asian vegetation

Understanding the threshold responses of vegetation to drought is essential for predicting and mitigating drought risk. Across Central Asia, extreme weather is expected to increase by the end of the 21st century. However, the threshold responses of different Central Asian vegetation types are not well understood. Here, we calculated drought indices for Central Asia based on meteorological data and remotely sensed vegetation indices from 2001 to 2020, used trend analysis to assess changes in drought and vegetation in Central Asia over the past 20 years, evaluated the threshold responses of five vegetation types to drought, and explored the drought causative factors of different vegetation types using coexistence analysis. All five Central Asian vegetation types responded to increasing drought in a nonlinear manner, and thus exhibited drought-responsive thresholds. Forests were the first responders to increasing drought, and wetlands were the least responsive overall. Grasslands, cultivated lands, shrublands, and forests crossed the drought threshold in different years between 2001 and 2020, with shrublands exhibiting the largest percentage of area crossing the threshold. Finally, the drought causative factor for grasslands, shrublands, and wetlands was soil moisture; for cultivated lands was precipitation; and for forests was saturated water vapor pressure difference. This study uncovers the characteristic responses of different Central Asian vegetation types to drought, and lays a theoretical foundation for drought assessment and ecological restoration in Central Asia.

Quantifying the Time-course of Changes in Maximal Skin Wettedness with 7 days of Heat Acclimation.

The aim of the present study was to quantify the time-course of changes in maximum skin wettedness (ωmax) - i.e., the proportion of skin surface area covered in sweat at the point of uncompensable heat stress, throughout 7 consecutive days of heat acclimation. Nine adults (6M, 3F) completed a humidity-ramp protocol (RAMP) on days 1, 3, 5 and 7 of seven consecutive days of heat acclimation. In each RAMP trial, participants cycled continuously at 275 W·m-2 for 120 min at 37°C: 60-min at a vapour pressure of 2.05 kPa followed by 60-min with vapour pressure increased by 0.045 kPa·min-1. An upward inflection in esophageal temperature (Teso) signaled a transition to uncompensable heat stress with the critical water vapour pressure at that point used to calculate ωmax. In days between RAMP assessments participants cycled for 90-min at 75% HRmax at 37°C, 60% RH. Teso, whole-body sweat rate (WBSR), local sweat rate (LSRback, LSRarm) and activated sweat gland density (AGSD) were measured throughout. ωmax was progressively and significantly greater from Day 1 (0.68±0.10) to Day 3 (0.75±0.10;P=0.002), to Day 5 (0.79±0.10;P=0.004), to Day 7 (0.87±0.06;P=0.009). WBSR was higher on Day 5 (1.11±0.30 L·h-1;P=0.01) and Day 7 (1.12±0.19 L·h-1;P<0.001) compared to Day 1 (0.94±0.21 L·h-1). ASGD was higher on Day 5 (78±15 glands·cm-2;P<0.001), and Day 7 (81±17 glands·cm-2;P=0.001) compared to Day 1 (65±12 glands·cm-2). There were no observed differences in sweat gland output (P=0.21). In conclusion, ωmax significantly increased throughout 7 days of heat acclimation. These progressive increases in ωmax were predominantly mediated by an increase in the number of active sweat glands, not the output per gland.

Analysis of the influence of thermal insulation parameters on the effectiveness of enclosing structures and building heating systems

The results of thermal engineering calculations of external multilayer enclosing structures of buildings and the thermal power of the heating system of residential buildings are presented, including calculations of temperature fields and partial pressures of water vapor at various parameters of structural layers and thermal insulation layers. Variants are considered and an assessment is given of the variation of parameters and the different location of thermal insulation in external multilayer fences for changes in temperature fields and partial pressures of water vapor in the fence, as well as for changes in the thermal power of the heating system of the building premises for two climatological design areas. The calculations were performed according to the methodology presented below using a specially developed computer program.

Reaction-controlled triple O-isotope exchange trajectories during experimental alteration of olivine

The measurements and application of triple O-isotope system is a relatively new and powerful tool in tracing water-rock interaction, allowing to distinguish the temperature-dependent fractionation from the water amount that interacted with the rock. While the use of 18O/16O fractionation between minerals and fluids is well-established, most natural mineral-water reactions remain uncharacterized in terms of the triple isotope fractionation (17O/16O and18O/16O). The triple O-isotope approach is especially promising when it comes to natural samples, where an array of exchanged samples constrains the fluid endmembers. However, multiple exchange mechanisms are likely to occur between the reacting rock and water, which has not been investigated for triple O-isotopes. This study examines the triple O-isotope exchange between fluid and olivine experimentally, as this is a common reaction in nature and mechanisms/rates of reaction are societally important for CO2 sequestration. Water-olivine reaction in batch experiments was investigated at 275 °C at the saturated water vapor pressure of 59.5 bar. Reactants were loaded at mass ratios 0.6 to 2 and exchanged for periods of time between 44 and 1048 h. Local meteoric water and mantle olivine were taken as the initial reactants. The mineral products are brucite, serpentine and minor magnetite that occur as coatings on unreacted olivine as well as individual crystals. The progress of this dissolution-precipitation reaction was traced with the δD-δ′18O-Δ′17O values of reacted fluids and mineral products. After 1048 h of reaction, ∼50 wt% of unreacted olivine remained. In general, experimental data conforms with the triple O-isotope fractionation factors calculated for the co-existing secondary minerals forming in equilibrium with fluid. However, there is scatter and deviations in the reacted fluid compositions likely driven by the difference in relative rates of secondary mineral formation and changing modal and chemical mineral composition. We observe that brucite and magnetite form abundant aggregates early in the progress of the reaction, while chrysotile forms fine-grained coatings that become abundant later. Since individual mineral-water fractionation 103ln18/16α range over 10 ‰ with θ ranging between 0.51 and 0.53, the dynamic behavior of dissolution-precipitation mechanism during alteration of olivine is the main factor to the “wandering” triple O-isotope trajectories in our relatively short experiments.

Seasonal Prediction Model for Airborne Pollen Content in Beijing Urban Area

Airborne pollen is considered to be one of the air pollutants that can cause allergic reactions in humans, leading to the occurrence or aggravation of a series of allergic diseases. The latest study showed that the positive rate of pollen allergens in allergic rhinitis patients in urban areas of Beijing exceeded 80%. Accurate prediction of pollen content could provide more effective assistance to susceptible populations. Based on the measured data from multiple stations in the urban area of Beijing during the pollen season from 2021 to 2022, the spatiotemporal distribution characteristics of pollen content were analyzed. The results showed that the main meteorological factors affecting spring pollen content in the urban area of Beijing were daily average wind speed, 3-day average temperature, water vapor pressure, daily average, temperature, and accumulated temperature. The main meteorological factors affecting autumn pollen content were 3-day average temperature, water vapor pressure, minimum surface temperature, and daily average temperature. In addition, it was found that there was a consistent spatial correlation between the current air pollen content and meteorological elements in the urban area of Beijing, but this correlation had significant seasonal differences. Furthermore, the Granger causality test method was applied to select the main meteorological factors that affected airborne pollen content in the urban area of Beijing, and two prediction models for air pollen content in the Beijing urban area for different seasons were established based on the support vector machine method （SVM） and multiple linear regression theory. The test of the prediction results for 2023 showed that both the SVM model considering seasonal differences and the multiple linear regression model could predict the daily distribution trend of pollen content well. The overall correlation coefficients between the predicted pollen content and the measured values were 0.693 and 0.636 （P &lt;0.01）, respectively. Additionally, both models had good predictive ability for several severe content pollen pollution events within the year. In the spring of 2023, the prediction accuracy of the SVM model and linear model were 61.2% and 60.1%, respectively. During autumn, the prediction accuracy was 68.1% and 66.7%, respectively. The performance was better than that of existing business models, especially in the cross-level error improvement of heavy pollution event prediction. The research results provide reference value for further improving the prediction technology of airborne pollen content in the Beijing area.

Spatio-temporal changes in atmospheric aridity over the arid region of Central Asia during 1979–2019

The arid region of Central Asia (CA) is the largest non-zonal arid region in the world. It has experienced significant changes in climate and hydrological cycle systems owing to global warming, which has posed serious impacts on the water resources and ecological environment in this region. Although the atmospheric water vapor pressure deficit (VPD) can directly reflect the atmospheric moisture condition, studies on the change of atmospheric moisture deficit in CA are scarce. Thus, we investigated the changes in VPD in the arid region of CA from the perspective of atmospheric aridity based on the CRU TS4.04 and ERA5 data. Our results showed that the VPD in more than 95 % of grids in the arid region had a significantly increasing trend during 1979–2019. Seasonally, VPD trends were increasing in spring, summer, and autumn but decreasing in winter. The changes in saturated water vapor pressure and actual water vapor pressure determined the VPD changes. The saturated water vapor pressure showed a clearly upward trend, whereas the actual water vapor pressure did not increase at the same rate, resulting in the increase of VPD. The first four leading modes revealed by empirical orthogonal function (EOF) analysis represented the patterns by explaining 81.4 % of the total variance. The positive phase of EOF1 was characterized by a monopole pattern, and this mode continued to increase. Contrastingly, EOF2 (and EOF3) showed dipole patterns over east–west CA (and north–south CA), with a mainly interannual variability. Due to the combined effect of increasing temperatures and decreasing relative humidity, the VPD has been intensifying since the mid-to-late 1990 s in CA, and the atmosphere has become significantly drier. These research results can deepen the scientific understanding of global warming impacts on atmospheric moisture and provides a reference for revealing the VPD changes and their impacts on the climate system and ecosystem in arid regions. Our results highlight that the impacts of VPD change should be adequately considered in environmental management and policy-making processes in Central Asia.

Detectability of biosignatures in warm, water-rich atmospheres

Warm rocky exoplanets within the habitable zone of Sun-like stars are favoured targets for current and future missions. Theory indicates these planets could be wet at formation and remain habitable long enough for life to develop. However, it is unclear to what extent an early ocean on such worlds could influence the response of potential biosignatures. In this work we test the climate-chemistry response, maintenance, and detectability of biosignatures in warm, water-rich atmospheres with Earth biomass fluxes within the framework of the planned LIFE mission. We used the coupled climate-chemistry column model 1D-TERRA to simulate the composition of planetary atmospheres at different distances from the Sun, assuming Earth's planetary parameters and evolution. We increased the incoming instellation by up to 50 percent in steps of 10 percent, corresponding to orbits of 1.00 to 0.82 AU. Simulations were performed with and without modern Earth’s biomass fluxes at the surface. Theoretical emission spectra of all simulations were produced using the GARLIC radiative transfer model. LIFEsim was then used to add noise to and simulate observations of these spectra to assess how biotic and abiotic atmospheres of Earth-like planets can be distinguished. Increasing instellation leads to surface water vapour pressures rising from 0.01 bar (1.31&lt;!PCT!&gt;, S = 1.0) to 0.61 bar (34.72&lt;!PCT!&gt;, S = 1.5). In the biotic scenarios, the ozone layer survives because hydrogen oxide reactions with nitrogen oxides prevent the net ozone chemical sink from increasing. Methane is strongly reduced for instellations that are 20&lt;!PCT!&gt; higher than that of the Earth due to the increased hydrogen oxide abundances and UV fluxes. Synthetic observations with LIFEsim, assuming a 2.0 m aperture and resolving power of a R = 50, show that ozone signatures at 9.6 mu m reliably point to Earth-like biosphere surface fluxes of O$_2$ only for systems within 10 parsecs. The differences in atmospheric temperature structures due to differing H$_2$O profiles also enable observations at 15.0 mu m to reliably identify planets with a CH$_4$ surface flux equal to that of Earth's biosphere. Increasing the aperture to 3.5 m and increasing instrument throughput to 15&lt;!PCT!&gt; increases this range to 22.5 pc.

Enhancing GNSS tropospheric delay corrections through an innovative lapse rate grid and adiabatic modelling

Since measurements of meteorological parameters like air pressure, water vapor pressure, and temperature are typically not conducted at the receiving antenna’s height, accurate vertical adjustments are indispensable for the tropospheric delay calculation in GNSS applications. We developed an enhanced GPT3 model named as GPT3a, incorporating a new temperature lapse rate grid model and the adiabatic method. The capabilities of GPT3a in predicting atmospheric parameter profiles are assessed by comparison with radiosonde data, NCEP reanalysis data, and GNSS data. Compared with GPT3, IGPT, UNB3, and the constant model with a value of 6.5 K/km, the accuracy of the GPT3a is improved by 50 %, 26 %, 21 %, and 31 % respectively in predicting lapse rate. The RMSEs of GPT3a, GPT3 and IGPT, across temperature profiles (4.2 K, 10.7 K and 6.6 K, respectively), pressure profiles (5.7 hPa, 18.7 hPa and 6.8 hPa, respectively), and ZHD profiles (16.4 mm, 36.4 mm and 17.5 mm, respectively), demonstrate that GPT3a performs superiorly to the GPT3 and IGPT models. Moreover, in the GNSS-based water vapor retrieval, when there is a large height difference between GNSS sites and the model, the GPT3a obviously outperforms GPT3. In short, GPT3a can be used as an enhancement of GPT3 to support GNSS positioning, GNSS meteorology and atmospheric research, which extends the applicability of GPT3 beyond the Earth’s surface to airspace.

Improving Liquid Desiccant Dehumidifiers through Square Baffle Plate Design and Nanofluid Innovation

Enhancing the performance of the liquid desiccant dehumidifier (LDDs) is pivotal, with mass transfer playing a significant role. Compared to the previous method, using a baffles plate improved liquid desiccant dehumidification performance. The study utilized an aqueous solution containing nanocarbon tubes (NCTs) in LiCl/H2O as the desiccant, cascading over baffles plate with a square profile. The performance of this system was determined using numerical methods. The concentrations of NCTs ranged from 0.03% to 0.5% by weight. Furthermore, this paper investigates the impact of nanoparticles and parameters, including flow rates, solution concentration, humidity, solution temperature, etc. on the analysis through Computational Fluid Dynamics (CFD) simulation. The study shows a 29% increase in moisture removal and humidity change, along with a 15.57% improvement in film thickness. These findings are underpinned by the principle of a reduced in contact angle from 57° to 29°, resulting in reduced partial pressure of water vapor from the solution, thereby enhancing the mass transfer mechanism. Consequently, the utilization of baffles plate demonstrates a significant improvement in the moisture removal performance of the LDDs.

Low‐temperature bubble formation in silica glass

AbstractPhase separation was observed in silica glass following low‐temperature heat treatment in high water vapor pressure through the formation of bubbles. Although the 6 day diffusion treatment in saturated water vapor pressure at 250°C does not normally cause phase separation, the reactive fracture surface and subsurface damage caused by polishing with cerium oxide (CeO2) allowed for an increase in water absorption during treatment and heterogeneous nucleation of the bubbles at damaged sites. The sub‐surface damage, characteristic of blunt contact damage, was only revealed when the polished sample was etched. The formation of bubbles and polishing damage were observed in two silica glasses—one containing chlorine impurities and the other containing OH impurities. Raman spectra collected after fracture or polishing and water diffusion treatment demonstrated an increase in the abundance of –OH species including silanol (SiOH) groups and an evolution in the glass structure in the bubble regions compared with the bubble‐free regions. These results indicate an increase in the reactivity between water and glass fracture surfaces relative to the bulk.

Synthesis and Characterization of Calcium Sulfoaluminate Hydrates-Ettringite (AFt) and Monosulfate (AFm).

The goal of the presented work was to find the most favorable conditions for the synthesis and stabilization of chemically pure ettringite and monosulfate. The reaction was carried out by mixing pure tricalcium aluminate (C3A) and gypsum (CS¯H2) in an excess amount of water. The impact of hydration time (2-7 days), C3A:CS¯ molar ratio (1:1-1:3) and water vapor pressure of the selected drying agents (anhydrite-III and supersaturated CaCl2 solution) on the phase composition of the products was evaluated. After 7 days of hydration, either ettringite or monosulfate was obtained as the main product, depending on the C3A:CS¯ molar ratio. The synthesis carried out at a C3A:CS¯ molar ratio of 1:3 produced pure ettringite. In the case of the sample characterized by the ratio of 1:1 (typical of monosulfate), a considerable portion of ettringite (27.9%) was present in the final products along the AFm phase. Therefore, a different synthesis method has to be selected in order to obtain pure monosulfate. The results showed that thermal analysis, X-ray diffractometry and FTIR spectroscopy can be used to distinguish the characteristic features of ettringite and monosulfate.

A molecular study of CO2 adsorption performance of functionalized Mg-MOF-74 at different water vapor concentrations and pressures

This study numerically evaluates the CO2 adsorption capability of functionalized Mg-MOF-74 at different water vapor concentrations and pressures. The −O-Li- and –NO2 display the most advantageous adsorption locations for CO2 and enhance the adsorption energy for H2O within the secondary building unit region. The enhancement of CO2 adsorption at 1 bar is achieved through the incorporation of Li-O and –NO2, whereas introducing –CH3 improves the selectivity of Mg-MOF-74 towards CO2/H2O. The absorption of CO2 at 10 bar is influenced by the available void space within the pores and altering the functional groups leads to a reduced porosity, thereby hindering the CO2 adsorption. However, –CH3 can effectively improve the CO2/H2O selectivity. The increased CO2 adsorption sites by the functionalization is more advantageous for enhancing CO2 adsorption capacity in gas/vapor mixtures at low pressures. Furthermore, enhancing absorbent hydrophobicity results in an enhanced selectivity for CO2/H2O, thereby facilitating CO2 adsorption at elevated pressures.

Impact of broader ecological and socio-environmental components on Aedes mosquito population dynamics: a spatial-temporal longitudinal study.

The increasing spread of mosquito-borne diseases is a significant problem globally, but mosquito management strategies are less efficient. Therefore, a comprehensive understanding of the population dynamics of Aedes mosquito is essential for improving mosquito management strategies. Constructing a model to understand Aedes mosquito development in response to environmental factors is crucial to addressing these challenges. An extensive data set on Aedes spp. mosquito populations was constructed, considering the environmental factors temperature, water vapor pressure, wind speed, daylength, and rainfall. This data set, compiled from mosquito collections over a period of four years across multiple locations in Alabama, USA, facilitated the prediction of mosquito dynamics. The random forest model was used to explain mosquito population changes in response to these factors. These findings indicated that temperature, daylength, and water vapor pressure had the most significant impacts on mosquito population dynamics. The model also allowed predictions of mosquito population changes over time and across different geographic regions, extending beyond Alabama to the southeastern USA. This study provided valuable insights into the impacts of environmental factors on mosquito populations. This novel approach using machine learning and the random forest model will enable researchers to predict future mosquito populations and contribute to developing more-effective strategies for mosquito management. © 2024 Society of Chemical Industry. Published by John Wiley & Sons Ltd.

The Synergistic Effect of the Same Climatic Factors on Water Use Efficiency Varies between Daily and Monthly Scales

The coupled processes of ecosystem carbon and water cycles are usually evaluated using the water use efficiency (WUE), and improving WUE is crucial for maintaining the sustainability of ecosystems. However, it remains unclear whether the WUE in different ecosystem responds synchronously to the synergistic effect of the same climate factors at daily and monthly scales. Therefore, we employed a machine learning-driven factor analysis method and a geographic detector model, and we quantitatively evaluated the individual effects and the synergistic effect of climate factors on the daily mean water use efficiency (WUED) and monthly mean water use efficiency (WUEM) in different ecosystems in China. Our results showed that (1) among the 10 carbon flux monitoring sites in China, WUED and WUEM exhibited the highest positive correlations with the near-surface air humidity and the highest negative correlation with solar radiation. The correlation between WUEM and climate factors was generally greater than that between WUED and climate factors. (2) There were significant differences in the order of importance and degree of impact of the same climate factors on WUED and WUEM in the different ecosystems. Among the 10 carbon flux monitoring sites in China, the near-surface air humidity imposed the greatest influence on the WUED and WUEM changes, followed by the near-surface water vapor pressure. (3) There were significant differences in the synergistic effects of the same climate factors on WUED and WUEM in the different ecosystems. Among the 10 carbon flux monitoring sites in China, the WUED variability was most sensitive to the synergistic effect of solar radiation and photosynthetically active radiation, while the WUEM variability was most sensitive to the synergistic effect of the near-surface air humidity and soil moisture. The research results indicated that synchronous responses of the WUE in very few ecosystems to the same climate factors and their synergistic effect occurred at daily and monthly scales. This finding enhances the understanding of sustainable water resource use and the impact of climate change on water use efficiency, providing crucial insights for improving climate-adaptive ecosystem management and sustainable water resource utilization across different ecosystems.

Toward Water-Resistant, Tunable Perovskite Absorbers Using Peptide Hydrogel Additives.

In recent years, hydrogels have been demonstrated as simple and cheap additives to improve the optical properties and material stability of organometal halide perovskites (OHPs), with most research centered on the use of hydrophilic, petrochemical-derived polymers. Here, we investigate the role of a peptide hydrogel in passivating defect sites and improving the stability of methylammonium lead iodide (MAPI, CH3NH3PbI3) using closely controlled, in situ X-ray photoelectron spectroscopy (XPS) techniques under realistic pressures. Optical measurements reveal that a reduction in the density of defect sites is achieved by incorporating peptide into the precursor solution during the conventional one-step MAPI fabrication approach. Increasing the concentration of peptide is shown to reduce the MAPI crystallite size, attributed to a reduction in hydrogel pore size, and a concomitant increase in the optical bandgap is shown to be consistent with that expected due to quantum size effects. Encapsulation of MAPI crystallites is further evidenced by XPS quantification, which demonstrates that the surface stoichiometry differs little from the expected nominal values for a homogeneously mixed system. In situ XPS demonstrates that thermally induced degradation in a vacuum is reduced by the inclusion of peptide, and near-ambient pressure XPS (NAP-XPS) reveals that this enhancement is partially retained at 9 mbar water vapor pressure, with a reduced loss of methylammonium (MA+) from the surface following heating achieved using 3 wt % peptide loading. A maximum power conversion efficiency (PCE) of 16.6% was achieved with a peptide loading of 3 wt %, compared with 15.9% from a 0 wt % device, the former maintaining 81% of its best efficiency over 480 h storage at 35% relative humidity (RH), compared with 48% maintained by a 0 wt % device.

Augmentation strategy toward superior water absorption performance: An attempt utilizing [EMIm]Ac ionic liquid/water pair

Ionic liquids (ILs) offer significant advantages as alternative absorbents in absorption refrigeration cycles due to their superior physicochemical properties. Assessing the performance of new IL-based working pairs in absorption systems is essential for their rapid application in industrial applications. This study evaluates the water absorption performance of an aqueous solution of 1-ethyl-3-methylimidazolium acetate ([EMIM]Ac) under both saturated atmospheric and vacuum conditions. Additionally, the performance of an absorption chiller utilizing the [EMIM]Ac/H2O working pair was analysed using the Aspen Plus process simulator. A discrepancy was observed between the water vapor pressure in the air and the saturated vapor pressure of the aqueous solution at equilibrium. A theoretical criterion for the minimum relative humidity required for effective water vapor absorption by this absorbent at a given mass fraction is proposed. Under vacuum conditions, lower absolute pressure or higher mass fraction enhances absorption. Surfactants significantly improve absorption performance, with 2-octanol and 1-octanol demonstrating approximately double the absorption capacity compared to [EMIM]Ac. Higher mass fractions of the aqueous solution enhance the absorption rate but reduce the desorption rate. The coefficient of performance (COP) of the system decreases with increasing pressure and mass fraction, reaching a peak of 0.9 at a mass fraction of 20 % and a pressure of 3 kPa. Lower pressure and mass fraction enhance exergy efficiency.

Different States of water in α-Cyclodextrin hydrates

The pressure of saturated and unsaturated water vapor over α-CD·nH2O hydrates has been measured by static method with membrane-gauge manometer under conditions of complete loss of water. The temperature dependences of water vapor pressure have been obtained in the wide range of temperatures (287–469 K), pressures (0.04–34.95 kPa) and water content (0.17 ≤ n ≤ 6.0).The data obtained indicate the presence of water molecules with different volatility in α-CD·nH2O hydrates. Water molecules with lower volatility can be considered “external”, included in the network of intermolecular hydrogen bonds, while water molecules with higher volatility, discovered in our previous study, are considered “internal”, presumably located in the α-CD cavity. For each composition, the amount of “external” and “internal” water has been determined and the equations described the dependence of the content of each type of water on n in α-CD·nH2O have been obtained. The analytical expressions for the lnp – 1/T dependences as well as the values of enthalpy and entropy of processes studied have been calculated. Experimental data were used to obtain the Gibbs energy changes when “external” water molecules bind to the α-CD framework. The values obtained are differed from the values for “internal” water given in our previous study. The phase transition in α-CD·nH2O revealed in our previous study is also observed in this work and its thermodynamic characteristics are in good agreement with the results obtained earlier. The findings have been confirmed by 1H NMR studies.

Multiple-Win Effects and Beneficial Implications from Analyzing Long-Term Variations of Carbon Exchange in a Subtropical Coniferous Plantation in China

To improve our understanding of the carbon balance, it is significant to study long-term variations of all components of carbon exchange and their driving factors. Gross primary production (GPP), respiration (Re), and net ecosystem productivity (NEP) from the hourly to the annual sums in a subtropical coniferous forest in China during 2003–2017 were calculated using empirical models developed previously in terms of PAR (photosynthetically active radiation), and meteorological parameters, GPP, Re, and NEP were calculated. The calculated GPP, Re, and NEP were in reasonable agreement with the observations, and their seasonal and interannual variations were well reproduced. The model-estimated annual sums of GPP and Re over 2003–2017 were larger than the observations of 11.38% and 5.52%, respectively, and the model-simulated NEP was lower by 34.99%. The GPP, Re, and NEP showed clear interannual variations, and both the calculated and the observed annual sums of GPPs increased on average by 1.04% and 0.93%, respectively, while the Re values increased by 4.57% and 1.06% between 2003 and 2017. The calculated and the observed annual sums of NEPs/NEEs (net ecosystem exchange) decreased/increased by 1.04%/0.93%, respectively, which exhibited an increase of the carbon sink at the experimental site. During the period 2003–2017, the annual averages of PAR and the air temperature decreased by 0.28% and 0.02%, respectively, while the annual average water vapor pressure increased by 0.87%. The increase in water vapor contributed to the increases of GPP, Re, and NEE in 2003–2017. Good linear and non-linear relationships were found between the monthly calculated GPP and the satellite solar-induced fluorescence (SIF) and then applied to compute GPP with relative biases of annual sums of GPP of 5.20% and 4.88%, respectively. Large amounts of CO2 were produced in a clean atmosphere, indicating a clean atmospheric environment will enhance CO2 storage in plants, i.e., clean atmosphere is beneficial to human health and carbon sink, as well as slowing down climate warming.

The Usability of Metallurgical Production Waste as a Siliceous Component in Autoclaved Aerated Concrete Technology

The reconstruction of buildings is a complex process that often requires the consideration of the construction load when selecting correct building materials. Autoclaved aerated concrete (AAC)—which has a lower bulk density (compared to traditional masonry materials)—is very beneficial in such applications. A current trend in AAC development is the utilization of secondary raw materials in high-performance AAC, characterized by higher bulk density and compressive strength than regular AAC. The increase in bulk density is achieved by increasing the content of quartz sand in the mixing water. In this study, part of the siliceous component was replaced by ladle slag, foundry sand, furnace lining, and chamotte block powder. These materials are generated as by-products in metallurgy. The substitution rates were 10% and 30%. The samples were autoclaved in a laboratory autoclave for 8 h of isothermal duration at 190 °C with a saturated water vapor pressure of 1.4 MPa. The physical–mechanical parameters were determined, and the microstructure was described by XRD and SEM analyses. The results were compared with traditional AAC, with silica sand being used as the siliceous component. The measurement results show that sand substitution by the secondary raw material is possible, and it does not have a significant impact on the properties of AAC, and in a proper dosage, it can be beneficial for AAC production.

A novel model for the estimation of water vapor pressure and temperature considering diurnal variations in China

Water vapor pressure (e) and temperature (T) are essential tropospheric parameters in the Global Navigation Satellite System (GNSS) high-precision positioning navigation and GNSS meteorology. Current models for water vapor pressure and temperature exhibit insufficiently detailed vertical profiling and fail to effectively capture diurnal variations. For two tropospheric parameters, e and T, the empirical models of meteorological parameters in China, CET-H models, were established based on the fifth-generation European Center for Medium-Range Weather Forecasts Reanalysis (ERA5) reanalysis data and the elaborate diurnal variation from 2017 to 2019. The 2020 ERA5 atmospheric reanalysis data and radiosonde data are used as reference values and compared with the current GPT3 model with higher accuracy. The results show that: (1) The BIAS and Root Mean Square Error (RMSE) of e obtained by the CET-H model at the ERA5 surface are 0.18 hPa and 2.65 hPa, respectively, higher by 42.4 % compared to the GPT3 model. The BIAS and RMSE of T obtained by the CET-H model at the ERA5 surface are −0.90 K and 3.63 K, respectively, higher by 21 % compared to the GPT3 model. The atmospheric layer mean values of both models are superior to the GPT3 model in all seasons across different latitude bands. (2) The BIAS and RMSE of e obtained by the CET-H model at the radiosonde station are −0.05 hPa and 3.17 hPa, higher by 43 % compared to the GPT3 model. The BIAS and RMSE of T obtained by the CET-H model at the radiosonde station are 4.49 hPa and 6.80 hPa, higher by 15 % compared to the GPT3 model. The atmospheric layer mean values of both models are superior to the GPT3 model in all seasons across different latitude bands. Therefore, the new model will provide a new reference for GNSS meteorology.