High Relative Air Humidity Research Articles

Effects on the Indoor Environment in a Stable for Horses in Winter: A Case Study

The aim of this article is to show the most significant factors influencing the indoor environment in winter considering the operating conditions of an older stable modified for housing 12 horses and an indoor riding arena for teaching and sports purposes. This research focused on assessing the influences affecting the internal environment from the point of view of the construction of the building and ventilation control in the operating conditions of working and non-working days. The analysis of the results showed that the massive masonry structure has sufficient thermal insulation and accumulation, which was manifested by good temperature stability inside the stable of 7.2 ± 1.7 °C when the outside air temperature was −4.80 ± 1.5 °C. At low outdoor air temperatures of −6.44 ± 0.4 °C, the following conditions were found: a higher relative air humidity (76.0 ± 5.3%), a high CO2 concentration 2317.1 ± 931.7 ppm, and a high airborne dust concentration PM10 = 231.94 ± 19.13 μg·m−3 and PM2.5 = 160.13 ± 6.28 μg·m−3. Therefore, it is necessary to improve the solution and function of the stable ventilation. The small size of the windows and their uneven distribution (average daylight factor ei from 0.313 ± 0.154 to 0.835 ± 0.309) caused insufficient daylight in some individual boxes.

Kinetic and cracking analysis of paddy rice drying using refrigeration-assisted air dehumidification system

The presence of high relative air humidity in regions characterized by a humid climate results in a slow drying process and the rehydration of paddy. To address this issue, the utilization of a liquefied petroleum gas refrigeration system for the purpose of dehumidifying the ambient air has been shown to reduce drying time and enhance the quality of the final product. In the present investigation, the impact of ambient air dehumidification on the quality and moisture reduction of the Hashemi rice variety was examined. The drying of paddy was modeled and optimized using the Response Surface Method, taking into consideration three key factors: temperature (40, 45, and 50 °C), air velocity (1.7, 2.2, and 2.7 m/s), and relative air humidity (70, 80, and 90 %) as the variables in the conducted experiments. The findings of this study revealed that under dehumidification conditions, samples with a moisture content of 6 % exhibited the lowest cracking rate of 2 %. Moreover, the use of liquefied petroleum gas resulted in a 13 % reduction in cracking and drying times, ranging from 22.3 % to 68.9 %, depending on the experimental conditions. Irrespective of whether dehumidification was employed or not, the temperature was identified as the most influential parameter, impacting the experimental responses by 73.29 % and 73.09 % for the non-dehumidified and dehumidified conditions, respectively. Under optimal conditions, a cracking rate of 2 % was attained during dehumidification at a temperature of 40 °C, a relative air humidity of 80 %, and an air velocity of 1.7 m/s, yielding a desirability index of 0.958. The Response Surface Method, when applied in the dehumidification case, displayed an excellent fit between the experimental and predicted data for both the moisture content (R2 = 0.99) and the cracking index (R2 = 0.98). These results demonstrate the efficacy of the refrigeration system that employs liquefied petroleum gas inefficiently drying paddy in humid regions, rendering it applicable in industrial settings.

Production patterns of loblolly pine plantations along a geographic gradient in southern Brazil

Pinus taeda plantations depend directly on the supply of resources (light, water, and nutrients) available to the stand. However, studies quantifying edaphic and climatic factors in P. taeda stands are scarce. This study aimed to identify the main edaphic, climatic and stand factors that influence the productivity and growth pattern of P. taeda plantations in southern Brazil. A total of 24 stands, ranging between 8 and 10 years old were evaluated. Biometric variables such as height, diameter at breast height (DBH), stem analysis, growth rings, specific gravity, and soil chemical and physical variables were evaluated. Site index (SI), stem biomass, mean annual increment without bark (MAI) and correlations between variables were calculated. We observed that by nine years after planting, none of the plots had reached their maximum growth; and MAI, standing stem biomass and SI ranged from 15 to 35 m³ ha−1 year−1, 56–131 Mg ha−1, and 12–19 m, respectively, with higher values in Três Barras site. Stem biomass were positively related with SI (r = 0.89), and stem production was related with higher available water content (r = 0.41), warm temperatures (r = 0.61), and higher relative air humidity (r = 0.58). The study corroborates the role of nutrients, well-drained soils, mild climatic conditions, and low water deficit to explain the high yields of P. taeda in Brazil compared to other locations around the world. Based on these results, studies on fertilization, genetic material, and more frequent use of stem analysis, associated with X-ray densitometry, are recommended for P. taeda.

Thermodynamic analysis of drying cycles utilizing a desiccant wheel thermoelectric modules and heat pipe for the drying of hazel nuts in the East Blacksea climatic conditions

The use of renewable energy sources to maintain appropriate thermal humidity and temperature conditions in food drying technologies, especially in humid climate zones, is a current area of research. In the Eastern Black Sea Region, the high relative and specific humidity of the atmospheric air lead to a low drying rate of the products. Therefore, in this study, to enhance the drying rate of the products, three models and their psychometric cycles were studied on decreasing the specific humidity of the drying air and increasing the moisture saturation degree of the drying air. The innovative hazelnut drying models proposed for the climatic conditions of the Eastern Black Sea region incorporate several components, including thermoelectric modules (TEM), photovoltaic thermal (PV/T) systems, desiccant wheels (DW), heat pipes (HP) and heat exchangers (HX). The thermodynamic analysis was conducted on the theoretical cycles belonging proposed models. Emphasis was given to the development of Model-C, taking into account the drying conditions specific to hazelnuts in the Eastern Black Sea region, among the cycles named Model-A, Model-B and Model-C. The energy efficiencies and SEMER values of Model-A, Model-B and Model-C were presented based on selected atmospheric conditions. Each model is valid under its characteristic operating conditions, and the energy efficiencies, SEMER values and the exergetic efficiencies for Model-A, Model-B and Model-C were determined as (4.66%-0.271 kg-H2O kWh−1–62%), (9.87%-0.1542 kg-H2O kWh−1–22%) and (9.13%-0.1381 kg-H2O kWh−1–10%), respectively. Also, presented models of hazelnut drying supported by renewable energy have achieved high sustainable index (SI) values. Consequently, these models ensure the sustainability of energy in the drying sector and facilitate the assessment of their environmental, economic and social impacts. The utilization of renewable energy in the models will lead to a reduction in CO2 emissions during the drying process. These results indicate that TEM systems are a viable option for food drying in the future.

Impact of environmental factors on Biomphalaria pfeifferi vector capacity leading to human infection by Schistosoma mansoni in two regions of western Côte d'Ivoire

AbstractBackgroundIntestinal schistosomiasis remains a worrying health problem, particularly in western Côte d'Ivoire, despite control efforts. It is therefore necessary to understand all the factors involved in the development of the disease, including biotic and abiotic factors. The aim of this study was to examine the factors that could support the maintenance of the intermediate host and its vectorial capacity in western Côte d'Ivoire.MethodsData on river physicochemical, microbiological, and climatic parameters, the presence or absence of snails with Schistosoma mansoni, and human infections were collected between January 2020 and February 2021. Spearman rank correlation tests, Mann–Whitney, analysis of variance (ANOVA), and an appropriate model selection procedure were used to analyze the data.ResultsThe overall prevalence of infected snails was 56.05%, with infection reaching 100% in some collection sites and localities. Of 26 sites examined, 25 contained thermophilic coliforms and 22 contained Escherichia coli. Biomphalaria pfeifferi was observed in environments with lower land surface temperature (LST) and higher relative air humidity (RAH), and B. pfeifferi infection predominated in more acidic environments. Thermal coliforms and E. coli preferred higher pH levels. Lower maximum LST (LST_Max) and higher RAH and minimum LST (LST_Min) were favorable to E. coli, and lower LST_Max favored coliforms. The presence of B. pfeifferi was positively influenced by water temperature (T °C), LST_Min, RAH, and precipitation (Pp) (P < 0.05) and negatively influenced by pH, total dissolved solids (TDS), electrical conductivity (EC), LST_Max, and mean land surface temperature (LST). The parameters pH, TDS, EC, LST_Min, LST, and Pp had a positive impact on snail infection, while LST_Max had a negative impact on infection. Only pH had a positive effect on coliform and E. coli abundance. Of the 701 people examined for human schistosomiasis, 73.13% were positive for the point-of-care circulating cathodic antigen (POC-CCA) test and 12.01% for the Kato–Katz (KK) test. A positive correlation was established between human infections and the abundance of Biomphalaria (r2 = 0.879, P = 0.04959).ConclusionsThe results obtained reflect the environmental conditions that are conducive to the maintenance of S. mansoni infection in this part of the country. To combat this infection as effectively as possible, it will be necessary not only to redouble efforts but also to prioritize control according to the level of endemicity at the village level.Graphical

Increased heat stress for the population of urbanized areas against the background of global climate change

The combination of high temperature and relative humidity of the atmospheric air creates heat stress, which has a serious impact on the environment, society and the health of the population in urban areas. Using the example of the city of Kyiv, the paper investigated long-term changes in heat stress depending on global climate changes. Averaged monthly long-term climate data of the urban environment were studied, starting from 1981, based on monitoring data using the Copernicus Climate Change Service toolkit and data from the Borys Sreznevsky Central Geophysical Observatory. Predictive dynamics of temperature by conventional and wet bulb was investigated using OriginPro8 software. Data on the dependence of the frequency and unevenness of precipitation during the last decades are presented. The dependences of the value of the heat index (NI) on the temperature and air humidity for different observation periods were obtained. Over the past decade, Kyiv has seen a significant increase in average heat stress and the frequency of days and events with extreme heat stress. According to the obtained forecast estimates, in 2050 the heat index should increase by almost 30%, and the risk to the health of the population in the surrounding area and for workers in the open air will be interpreted as "high" levels at a relative humidity of 80%; "moderate" at a relative humidity of 50% and "low" at a relative humidity of 20%. The forecast temperature dynamics according to the conventional and according to the wet thermometer in the month of July at the end of different years is: 2021–2030 – 24.136°С and 26.24°С; 2030–2050 – 26.371°С and 28.918°С, respectively, with other equal conditions of the urban environment. An additional possibility of influence on the thermal dome appears already at the design stage, thanks to the variability of the placement of the projected buildings on the general plan, and the formation of individual buildings, in the correct area ratio green plantings to stone surfaces of facades and paving. The research data will be useful for the possible reduction of the size of the thermal dome over the city during the planning and reconstruction of the housing stock and the development of climate neutrality measures for the cities of Ukraine.

The Effect of Geoclimatic Factors on the Distribution of Paracoccidioidomycosis in Mato Grosso do Sul, Brazil.

The incidence of paracoccidioidomycosis (PCM) varies in Latin America, and it is influenced by environmental factors. This study evaluated the distribution of PCM acute/subacute form (AF) cases and their correlation with geoclimatic factors in the Mato Grosso do Sul (MS) state. The study included 81 patients diagnosed with the PCM/AF at the University Hospital of the Federal University of Mato Grosso do Sul between January 1980 and February 2022. Geographic coordinates, health microregion of patient's residence, compensated average temperature, relative air humidity (RH), El Niño Southern Oscillation (ENSO), and average global temperature were analyzed. The highest incidence was observed in the Aquidauana (7/100,000 inhabitants), while Campo Grande, the state's capital, had the highest number (n = 34; 42.4%) and density (4.4 cases/km2) of cases. The number of cases increased during extended periods of the El Niño phenomenon. A positive correlation was found between higher RH and PCM/AF cases. Most PCM/AF cases were found in areas with loamy soils and RH ranging from 60.8 to 73.6%. In MS, the health microregions of PCM/AF patients are characterized by deforestation for agricultural and pasture use, coupled with loamy soils and specific climatic phenomena leading to higher soil humidity.

Technical note: Isotopic fractionation of evaporating waters: effect of sub-daily atmospheric variations and eventual depletion of heavy isotopes

Abstract. Isotopic fractionation of evaporating waters has been studied constantly in recent decades, particularly because it enables calculation of both the volume of water evaporated from a water body and the isotopic composition of its source water. We studied the stable water isotopic composition of an artificial pan filled with water and subject to total evaporation in a sub-humid environment, in order to put into practice an operational method for estimating the time since disconnection of riverine pools when these are sampled for the quality of aquatic life. Results indicate that (i) when about 70 % of pan water had evaporated and its isotopic composition had become enriched in heavy isotopes, some subsequent periods of depletion instead of enrichment happened; and (ii) the customary application of isotopic fractionation equations to determine the isotopic composition of the water in the pan using weekly averaged atmospheric conditions (temperature and relative humidity) strongly underestimated the changes observed but predicted an early depletion of heavy isotopes. The first result, rarely reported in the literature, was found to be fully consistent with the early studies of the isotopic composition of evaporating waters. The second one could be attributed to the fact that weekly averages of temperature and relative humidity strongly overestimated air relative humidity during daylight periods of active evaporation. However, when the fractionation equations were parameterized using temperature and relative humidity weighted by potential evapotranspiration at sub-hourly time steps, they adequately reproduced the observed isotopic composition of the water in the pan, including the late periods of heavy isotope depletion. We demonstrate how weekly increases in air relative humidity when the pan water was already enriched in heavy isotopes led to their depletion. We also analyse the errors that can be incurred if time averages are used instead of flux-weighted meteorological data for model parameterization and if unidentified periods of heavy isotope depletion occur. Our results should be taken into account when applying fractionation equations, particularly in conditions or areas with high air relative humidity.

Impacts of high temperature, relative air humidity, and vapor pressure deficit on the seed set of contrasting maize genotypes during flowering

Heat stress is a major constraint to current and future maize production at the global scale. Male and female reproductive organs both play major roles in increasing seed set under heat stress at flowering, but their relative contributions to seed set are unclear. In this study, a 2-year field experiment including three sowing dates in each year and 20 inbred lines was conducted. Seed set, kernel number per ear, and grain yield were all reduced by more than 80% in the third sowing dates compared to the first sowing dates. Pollen viability, silk emergence ratio, and anthesis–silking interval were the key determinants of seed set under heat stress; and their correlation coefficients were 0.89***, 0.65***, and –0.72***, respectively. Vapor pressure deficit (VPD) and relative air humidity (RH) both had significant correlations with pollen viability and the silk emergence ratio. High RH can alleviate the impacts of heat on maize seed set by maintaining high pollen viability and a high silk emergence ratio. Under a warming climate from 2020 to 2050, VPD will decrease due to the increased RH. Based on their pollen viability and silk emergence ratios, the 20 genotypes fell into four different groups. The group with high pollen viability and a high silk emergence ratio performed better under heat stress, and their performance can be further improved by combining the improved flowering pattern traits.

128 Contribution of a Multi-Exposure Measurement Strategy on the Documentation of Cheese Workers' Exposures to Biological and Chemical Agents

Abstract A large-scale measurement campaign (9 days, more than 400 measurements) was conducted to characterise the exposure of cheese workers involved in maturing and packaging. Airborne microbial and chemical agents were measured in a company producing different types of cheeses. Several air pollutants were investigated (culturable microorganisms, total particles, carbon dioxide, ammonia, VOCs etc.) by mean of ambient and personal measurements. A massive emission of particles into the air was found for tasks involving the brushing of a category of cheeses, with significant personal exposures to culturable fungi (up to 108 CFU/m3_filter cassettes_2L/min). Dominant fungi belonged to Penicillium species with allergenic potential. Ripening rooms can contain high concentrations of carbon dioxide and several tasks performed in them have shown high individual exposures levels (instantaneous concentration up to 10 000 ppmv_ToxiRAE Pro CO2 portable detector). High relative air humidity (&amp;gt; 95%) was also found in the ripening rooms. Real-time measurement of airborne particles (FIDAS Frog particle counter) and gases (FTIR Gasmet™ gas analyser) allowed the identification of events (ventilation, door opening, etc.) that could affect pollutant concentrations and flows. The observed exposure of cheese worker to funig represents an immuno-allergic risk and their exposure to carbon dioxide appeals attention. The multiple nature of exposure raises questions about the technical and organisational mitigation strategies to implement. The multi-exposure measurement strategy deployed in the company proved to be relevant and allowed for a more comprehensive risk assessment. It provided valuable information for formulating prevention recommendations appropriate to the situation. A study including several cheese companies is in course.

Respiratory infections among junior high school students in upper northern Thailand: The role of building dampness and mould, biomass burning and outdoor relative air humidity (RH)

BackgroundFew studies exist on environmental risk factors for respiratory infections in Thai school children. AimTo study associations between home and outdoor environment and respiratory infections among school children in Northern Thailand in dry and wet season. MethodsA repeated questionnaire survey among the children (N = 1159). Data on ambient temperature and relative air humidity (RH) and PM10 and ozone was collected from nearby monitoring stations. We used logistic regression to calculate odds ratios (OR). Results14.1% had current respiratory infections (last 7 days), 32.1% had any respiratory infection last 3 months, and 26.1% had any respiratory infection last 12 months with antibiotic treatment. Students with diagnosed allergy (7.7%) and diagnosed asthma (4.7%) had more often respiratory infections (ORs 1.40–5.40; p < 0.05). Current respiratory infections were more common in dry (18.1%) than in wet season (10.4%) (p < 0.001) and was associated with indoor mould (OR 2.16; p = 0.024) and outdoor RH (OR 1.34 per 10% RH; p = 0.004.) in the total material. In wet season, mould (OR 2.32; p = 0.016), window pane condensation (OR 1.79; p = 0.050), water leakage (OR 1.82; p = 0.018), environmental tobacco smoke (ETS) (OR 2.34; p = 0.003) and outdoor RH (OR 2.70 per 10% RH; p = 0.01) were risk factors for current respiratory infections. In dry season, mould (OR 2.64; p = 0.004) and outdoor RH (OR 1.34 per 10% RH; p = 0.046) were associated with current respiratory infections. Irrespectively of season, biomass burning inside or outside the home was a risk factor for respiratory infections (ORs 1.32–2.34; p < 0.05). Living in a wooden house decreased the risk of respiratory infections (OR 0.56: p = 0.006). ConclusionsDry season, high outdoor RH, household dampness, indoor mould and ETS can increase childhood respiratory infections. Living in a traditional wooden house can reduce respiratory infections, possibly due to better natural ventilation. Smoke from biomass burning can increase childhood respiratory infections in northern Thailand.

Diversity and assembly of lichens and bryophytes on tree trunks along a temperate to boreal elevation gradient.

Based on hypotheses related to environmental filtering vs. stochastic community assembly, we tested taxon-specific predictions regarding the relationships of alpha diversity, beta diversity and species composition of epiphytic macrolichens and bryophytes with elevation and the lateral gradient on trees (the different sides of the tree bole related to aspect and trunk inclination) at Parc national du Mont-Mégantic in Southeastern Québec, Canada. For lichens on firs, increasing elevation was associated with increasing alpha diversity, and a marked shift in community composition, at the scale of whole trees. In contrast, for bryophytes on maples, tree inclination and the lateral gradient had the strongest effects: more inclined trees had greater whole-tree alpha diversity and stronger within-tree contrasts in composition between the upper and lower bole surfaces. For lichens on maples, whole-tree alpha diversity showed a weak, negative relationship with inclination, and beta diversity increased slightly with elevation. Our results are consistent with theories predicting greater alpha diversity in more favorable environments (for lichens: high elevation with high relative air humidity and lower temperatures; for bryophytes: upper surfaces of tree boles with liquid water available), but support was weak for the prediction of greater beta diversity in more favorable environments. Overall, the important predictors of epiphytic cryptogam diversity vary more among the species of tree host (maple vs. fir) than focal taxa (lichens vs. bryophytes), with patterns likely related to different effects of water, temperature, and competition between lichens and bryophytes.

CO2 emissions from reed litter in the air and on the soil surface in the Yellow River Delta, China

The decay of litter in the air (that is, standing litter) and on the ground is an essential process of litter decomposition for many plant species. However, the contribution of standing litter to litter decomposition (e.g., CO2 emission) is still ambiguous, especially for non-leaf litter. In this study, we examined the CO2 emission from reed litter (Phragmites communis) in coastal wetlands in the Yellow River Delta (YRD), China. The results showed that the soil litter released more CO2 than the standing litter due to its rapid loss of labile organic carbon and high enzyme activities (that is, invertase and β-glucosidase). In contrast, cumulative CO2 emissions from standing litter were equivalent to 56%–70% of those on the soil surface, indicating that CO2 emissions from standing litter cannot be ignored. The sheath litter had the highest cumulative CO2 emission per unit of dry biomass among the three types of litter. Taking into account the biomass per unit area, the non-leaf litter (that is, culm and sheath) emitted more CO2 than leaf litter. On the daily scale, the litter released more CO2 at night than in the daytime, because low air temperature and high relative air humidity at night can help dew formation, accelerating CO2 emission at night. On the seasonal scale, air temperature and relative air humidity were positively related to CO2 emission, leading to rapid CO2 emission in summer and fall. The Q10 value of CO2 emission from standing litter (an average of 1.44) was lower than that of litter on the ground (an average of 2.16) due to a low residual rate of recalcitrant organic carbon in standing litter. Our findings highlight that standing litter decomposition should not be overlooked and suggest that more attention should be paid to the decay of non-leaf litter in the coastal wetland of the YRD.

A research agenda for nonvascular photoautotrophs under climate change.

Nonvascular photoautotrophs (NVP), including bryophytes, lichens, terrestrial algae, and cyanobacteria, are increasingly recognized as being essential to ecosystem functioning in many regions of the world. Current research suggests that climate change may pose a substantial threat to NVP, but the extent to which this will affect the associated ecosystem functions and services is highly uncertain. Here, we propose a research agenda to address this urgent question, focusing on physiological and ecological processes that link NVP to ecosystem functions while also taking into account the substantial taxonomic diversity across multiple ecosystem types. Accordingly, we developed a new categorization scheme, based on microclimatic gradients, which simplifies the high physiological and morphological diversity of NVP and world-wide distribution with respect to several broad habitat types. We found that habitat-specific ecosystem functions of NVP will likely be substantially affected by climate change, and more quantitative process understanding is required on (1) potential for acclimation, (2) response to elevated CO2 , (3) role of the microbiome, and (4) feedback to (micro)climate. We suggest an integrative approach of innovative, multimethod laboratory and field experiments and ecophysiological modelling, for which sustained scientific collaboration on NVP research will be essential.

Potable water generation from atmospheric moisture in coastal areas using the thermoelectric effect

Although water covers more than two-thirds of the globe’s area by a percentage of approximately 70 %, safe potable water is still scarce and therefore many countries where freshwater resources are scarce have directed to conduct many research and studies to find a suitable way to provide potable water, from this standpoint, many countries that possess coasts on the sea, including Egypt, have tended to desalinate seawater, but this method is very expensive and may be disrupted for various technical reasons such as lack of energy to operate or damage mechanical parts, and this is what happened recently in the Egyptian northern coast and the Red Sea islands. They depend on desalination plants or bottles of mineral water extracted from wells to meet their potable water needs. This article aims to solve the problem of potable water scarcity in the northern coast of Egypt, which is characterized by the high relative humidity of air in the atmosphere (60-80%) by designing a portable potable water capture device that depends on the (Peltier Effect) and takes the energy necessary to operate it from solar energy. This device can generate 2.86 L/h of fresh potable water at a temperature of 30 O C and Relative humidity of R.H = 60 %.

High relative humidity improves leaf burn resistance in flowering Chinese cabbage seedlings cultured in a closed plant factory.

Plant factories that ensure the annual production of vegetable crops have sparked much attention. In the present study, thirty types of common vegetable crops from 25 species and eight families, were grown in a multi-layer hydroponic system in a closed-type plant factory to evaluate the adaptive performance. A total of 20 vegetable crops, belonging to 14 species and 4 families, unexpectedly exhibited different degrees of leaf margin necrosis in lower leaves firstly, then the upper leaves gradually. We defined this new physiological disorder as "leaf burn". It occurred more commonly and severely in cruciferous leafy vegetables. Two different light intensities (150 and 105 µmolm-2s-1 photosynthetic photon flux density (PPFD)), three photoperiod conditions (12, 10 and 8 hd-1) and two canopy relative air humidity (RH) (70% and 90% RH) were set to evaluate the suppression effects on leaf burn occurrence in two commercial flowering Chinese cabbage cultivars ('Sijiu' and 'Chixin'), the special cruciferous vegetable in South China. We discovered that changing light conditions did not fully suppress leaf burn occurrence in the cultivar 'Sijiu', though lower light intensity and shorter photoperiod partly did. Interestingly, the occurrence of leaf burn was completely restrained by an increased canopy RH from 70% to 90%. Specifically, the low RH-treated seedlings occurred varying degree of leaf burn symptoms, along with rapidly decreased water potential in leaves, while the high RH treatment significantly lessened the drop in leaf water potential, together with increased photosynthetic pigment contents, net photosynthetic rate, stomatal conductance and transpiration rate, decreased leaf stomatal aperture and density, and thus reduced the incidence of leaf burn in 'Sijiu' and 'Chixin', from 28.89% and 18.52% to zero, respectively. Taken together, high canopy RH may favor maintaining leaf water potential and improving photosynthesis performance, jointly regulating leaf burn incidence and plant growth.

Depth distribution and chemistry of salts as factors controlling tafoni and honeycombs development

Salts play a pivotal role in the processes forming tafoni and honeycombs but only few studies have focused on their areal and depth distribution. An X-ray diffraction, rock leachates chemistry, and evaporation front depth were combined to get a deeper insight into factors controlling salt composition and distribution. Five sites representing various lithological and/or climate conditions were studied. The data show that salt composition is a result of the interaction between chemical compositions of rainwater and lithology. Gypsum was found to be a major salt on all sites with halite dominating in arid sites. On humid sites the high relative air humidity prevents its precipitation. Gypsum and epsomite dominate also on sites where the rock contains a considerable amount of pyrite. Alum-(K) occurs in quartz sandstones when affected by acid rain. Some ions probably occur in residual brines, rather than precipitated salts (CaCl in arid or NaCl in humid sites). On arid sites, the salt content in the tafoni backwalls is 4–20 times higher than in outer walls and rapidly decreases with depth which is consistent with shallow evaporation front in backwalls. The low salt content in the outer walls reflects the dilution effect of surface runoff after rains and the infiltration of water through the outer walls toward depth. In two humid sites, on the contrary, no differences were found between the salt content of the backwalls and the outer walls. At one site the data shows that the whole surface of tafoni serves as the salt precipitation zone and tafoni are thus recently degrading. The honeycomb site differs from all tafoni sites since the honeycombs are mostly protected from rain runoff, which prevents the washing-out of salts even from the outer walls.

Variability of soybean yield and seed quality depending on environmental hydrothermal factors

Variability of soybean yield and seed quality depending on environmental hydrothermal factors

Experimental investigation on water vapor permeability in porous dust layers on cold fin surface of heat exchanger

Removing the dust layers on a heat exchanger of air conditioner by impelling the permeated water to freeze and expand is a promising technique to avoid the heat transfer performance deterioration, and the key for this technique is to permeate enough water vapor by controlling the operation conditions of air conditioners. The purpose of this study is to obtain the influence law of operation conditions on the water vapor permeation mass in dust layers, and experimental investigations are carried out covering the representative conditions of air conditioners, e.g., the inlet air relative humidity ranging from 15% ∼ 90% and the fin temperature ranging from 2 ∼ 8°C. The results show that the water vapor may preferentially permeate into the pore channels constructed by adjacent dust particle aggregates, and the water vapor condensation may block the pore channels and prevent the further water vapor permeation. High relative humidity of inlet air or low temperature of fin facilitates the water vapor permeation, and the maximum water vapor permeation mass increased by 21.8% and 20.6% respectively as the relative humidity increases or the fin temperature decreases, while the water vapor may not permeate into the porous dust layer if the relative humidity is lower than a threshold value. It can be concluded that, in order to improve the dust removal effectiveness by the enhancement of water vapor permeation, the fin temperature should be controlled adaptively according to the relative humidity in the actual operation environment of air conditioners.

A two-phase model for simulation of water transfer during lipase production by solid-state cultivation in a tray bioreactor using babassu residues as substrate

This research aimed to model and to simulate water transfer during lipases production by solid-state cultivation of the fungus Metarhizium anisopliae using babassu coconut bagasse as substrate in a pilot-scale tray bioreactor. A material balance was applied for water and individual equations for drying processes were adapted for both solid and gas phases. Physical and thermal properties of the bed, fermentation process conditions and microbial were determined experimentally or extracted from literature. Simulations were run in Matlab R2019a. Results showed that inlet air with 50% relative humidity is predicted to cause severe reduction in the moisture content of the solid matrix up to half of the trays' total length. Afterwards, air and solid reach the equilibrium and the drying process stops. Substrate dries when the air is introduced with 50% relative humidity independently of its velocity. By keeping the temperature of the solid-phase constant, fungal growth is limited by its water activity. For high relative humidity (95%) of the inlet air, the water activities are predicted to remain above 0.97 throughout the cultivation and on the entire length of the tray, ensuring the optimal fungal growth. The model proposed is a powerful tool for guiding the bioreactors scale-up.