Investigation of relative humidity effects on the response behavior of a pH indicator-based OWG vapor sensor

Field observations in four pear orchards during 5 years from April to October indicated that days with uninterrupted wetness of variable length represented 83.9% of the total days studied. However, days with surface wetness interruptions and with high relative humidity (RH) (>/=90%) without wetness occurred with a frequency of 7.1 and 6.2%, respectively. Accordingly, the effect of interruption of 24-h wetness periods by dry periods of high or low RH on infections caused by Stemphylium vesicarium on pear was determined. Pear plants inoculated with conidia of S. vesicarium were exposed to a 12-h wet period followed by a dry period of variable length (0, 3, 6, 12, 18, or 24 h) and a second wet period of 12 h. The dry period consisted either of low (60%) or high (96%) RH. The infection process was irreversibly stopped under low RH during dry periods between wetness, but continued at high RH. The effect of high RH on disease severity in the absence of wetness was also determined. Pear plants inoculated with S. vesicarium were exposed to periods of variable length (3 to 24 h) either at high RH (96%) in the presence of wetness or at high RH (96%) without wetness. No infections were observed on plants incubated under high RH without wetness, indicating that conidia of S. vesicarium require the presence of a water film in the plant surface to develop infections on pear.

Risk effects of high and low relative humidity on allergic rhinitis: Time series study

Effect of relative humidity on the uptake, translocation, and efficacy of glufosinate ammonium in wild oat ( Avena fatua)

Effects of relative humidity on the water repellency of fire-affected soils

In this study, an artificial neural network (ANN) approach was applied for modeling the relation between environmental variables and daily change in the Cleanness Index (ΔCI, a measure of performance loss due to soiling) of photovoltaic modules in the field in Doha, Qatar. The daily ΔCI was examined among a number of three-dimensional intervals of the daily mean of the environmental variables (i.e., the intervals of two environmental variables were presented on x and y dimensions, and average values of daily ΔCI on the third dimension), in order to qualitatively establish the relations that might help to develop improved PV soiling prediction models. Then, an ANN-based model was set up to simulate the relationship between daily ΔCI and environmental variables and compared with a linear regression model, both models using the same input variables, including present day and previous day environmental conditions, and cumulative exposure time. Strong interactions were observed among environmental variables PM10, relative humidity (RH) and wind speed (WS) regarding their effect on the daily ΔCI. Overall, higher PM10 resulted in more negative daily ΔCI (i.e. the module became more soiled), and this effect was more visible at low WS and RH levels, but at high WS (>4ms−1) and high RH (>65%) levels, PM10 had no significant (p>0.05, two tailed t-test) effect on daily ΔCI. Mostly, WS and RH determined how much airborne dust accumulates on the module surfaces and thereby affects the output of the PV modules. Higher WS typically favored more positive daily ΔCI when RH was low, but at higher RH levels (>50%) daily ΔCI was more likely to be negative with increasing WS. In fact, high RH levels were related to negative daily ΔCI only at higher WS levels (>2ms−1); at lower WS levels RH had no significant effect on daily ΔCI. These effects were apparently due to the deposition-resuspension mechanisms of dust accumulation on the PV panel surfaces. The ANN model performed significantly better in predicting daily ΔCIas well as cumulative CI than the linear model in term of R2 values and statistical error indexes. The previous day environmental conditions had a significant effect on the modeling outcome. The inclusion of the wind gustiness and cumulative exposure time also considerably improved the model prediction capability. The advantage of the ANN-based model is its simplicity, ease of data fitting and no requirement of an accurate mathematical model.

The quality of dried egg white with respect to functional properties can be affected by storage conditions. The effect of temperature and relative humidity (RH) on changes in colour and gelling properties in freeze-dried egg white (FDEW) during storage was investigated. The glass transition temperature (Tg ) of FDEW decreased with increasing % RH. The colour of FDEW stored at 60 °C was darker yellow than those at 40 and 25 °C, particularly at high % RH. RH had no effect on hardness and water-holding capacity (WHC) of gels made from FDEW stored at 25 °C for 1 week. However, hardness and WHC of gels from FDEW stored at higher temperatures; 40 °C, 48% RH and 60 °C, 11% RH dramatically increased. These results related to the differential scanning calorimeter thermograms which showed a broadening peak with lower enthalpy of protein denaturation. Moreover, the protein's SDS-PAGE pattern in the samples stored at high temperatures or RH levels showed protein aggregation. Storage of FDEW at high temperature and RH levels induced protein conformation changes. These have contributed to protein aggregation which affected the gelling properties of FDEW. © 2016 Society of Chemical Industry.

Abstract. The effect of relative humidity (RH) on secondary organic aerosol (SOA) formation from the photooxidation of m-xylene initiated by OH radicals in the absence of seed particles was investigated in a Teflon reactor. The SOA yields were determined based on the particle mass concentrations measured with a scanning mobility particle sizer (SMPS) and reacted m-xylene concentrations measured with a gas chromatograph–mass spectrometer (GC-MS). The SOA components were analyzed using a Fourier transform infrared (FTIR) spectrometer and an ultrahigh-performance liquid chromatograph–electrospray ionization–high-resolution mass spectrometer (UPLC-ESI-HRMS). A significant decrease was observed in SOA mass concentration and yield variation with the increasing RH conditions. The SOA yields are 14.0 %–16.5 % and 0.8 %–3.2 % at low RH (14 %) and high RH (74 %–79 %), respectively, with the difference being nearly 1 order of magnitude. Some of the reduction in the apparent yield may be due to the faster wall loss of semi-volatile products of oxidation at higher RH. The chemical mechanism for explaining the RH effects on SOA formation from m-xylene–OH system is proposed based on the analysis of both FTIR and HRMS measurements, and the Master Chemical Mechanism (MCM) prediction is used as the assistant. The FTIR analysis shows that the proportion of oligomers with C-O-C groups from carbonyl compounds in SOA at high RH is higher than that at low RH, but further information cannot be provided by the FTIR results to well explain the negative RH effect on SOA formation. In the HRMS spectra, it is found that C2H2O is one of the most frequent mass differences at low and high RHs, that the compounds with a lower carbon number in the formula at low RH account for a larger proportion than those at high RH and that the compounds at high RH have higher O : C ratios than those at low RH. The HRMS results suggest that the RH may suppress oligomerization where water is involved as a by-product and may influence the further particle-phase reaction of highly oxygenated organic molecules (HOMs) formed in the gas phase. In addition, the negative RH effect on SOA formation is enlarged based on the gas-to-particle partitioning rule.

Combined effects of high relative humidity and ultraviolet irradiation: Enhancing the production of gaseous NO2 from the photolysis of NH4NO3

Long-term transport and storage of peeled almonds under unsuitable conditions may cause the product's rejection. To get knowledge in this topic, peeled almonds were stored at 25°C and 60, 70, and 80% relative humidity (RH). The maintenance of high RH (80%) caused some visual defects after 4 months. Even though the 60, 70, and 80% RH did not clearly affect the production of primary and secondary products formed in the lipid oxidation during the 6 months of storage, sometimes an increase in the values of the specific extinction at the wavelength of 268nm (K268 ) was observed at 80% RH, suggesting the occurrence to some extent of secondary oxidation. Concerning microbial counts, the almonds stored at 60 and 70% RH presented a satisfactory microbial quality until 6 months; however, at 80% RH, the mold counts were higher than the reference values after 2 months. Several mycotoxins were detected at low levels, including aflatoxins B1 and G1, although some showed higher amounts at 80% RH. In general, it is recommended that almond producers and industrials should consider the use of low RH (<80%) for maritime transport and long-term storage of almond kernels. PRACTICAL APPLICATION: High levels of relative humidity during storage/transport of almond kernels favor fungal growth, mycotoxin production, and secondary oxidation (rancidity). It is recommended to keep the almond kernels under low RH(<80%) in maritime transport and long storage, especially in tropical countries.

Rising air pollution by surface ozone (O3) in China has induced extensive efforts to control ozone generation in major urban and industrial areas, yet mechanisms ruling the ozone production and loss are not well understood. In particular, ozone levels are strongly influenced by meteorological factors such as relative humidity, but this has been explored only in local situations, and the effect of relative humidity on ozone levels in warm seasons on a large scale in China is still unknown. Here we studied surface ozone, relative humidity, temperature, and other meteorological variables in 74 major cities in China during 2017–2018, focusing on the warm seasons in seven regions. Results show that ozone levels decrease with increasing relative humidity in all cities, with an average correlation coefficient of − 0.58, ranging from − 0.17 in Zhangjiakou to − 0.84 in Hengshui. At high relative humidity levels, above 75%, average ozone levels ranged from 44.6 to 122.5 μg m−3, which is lower than Chinese quality threshold of hourly average ozone level of 200 μg m−3. The decreases of ozone with relative humidity were more pronounced at high temperature, above 30 °C, than below 25 °C. The increases of ozone with temperature were more pronounced at low relative humidity, below 40%. Overall, our findings reveal that mechanisms ruling surface ozone levels are similar on a large scale. This is promising to design common methods of climate engineering to protect human health.

The use of fresh sage is increasingly popular due to its unique aroma and sensory characteristics. However, sage is a perishable fresh produce with a short shelf life, with limited knowledge of its storage conditions. This work investigated the effects of various temperatures (2, 6, and 20 °C) and relative humidity (RH) levels (atmospheric-65 % and high-95 %) on the quality characteristics of fresh sage during postharvest storage. The results indicated lower weight loss and respiration rate at lower temperatures and high RH. In addition, a higher phytochemical content (phenols, flavonoids, and ascorbic acid) and antioxidant activity were observed in sage stored at 2 and 6 °C (at a high RH level). Sage stored at 6 °C and 65 % RH, also presented higher phenolics and antioxidants. Storage at 20 °C resulted in higher microbial load compared to lower temperatures. Higher sage essential oil yield was found at plants stored at 6 °C, while camphor was also found at higher levels at this temperature. Thus, from the results, it could be suggested that postharvest storage of fresh sage at 6 °C along with high RH could contribute to the preservation of a fresh, aromatic fresh produce of high nutritional value.

Effects of relative humidity on childhood hand, foot, and mouth disease reinfection in Hefei, China

An integrated humidity sensor able to detect and measure a very low humidity concentration and higher relative humidity (RH) levels as well with the possibility of industrial application has been designed and fabricated using very large scale integration technology where thin porous Al2O3 film acts as humidity sensing material. The porous structure of Al2O3 has been obtained by anodic oxidation of a thin film of Al in sulfuric acid. During anodic oxidation, a few top atomic layers of Ta are also oxidized into Ta2O5 whose properties affect the normal sensing properties of Al2O3 and a better quality of sensor with higher sensitivity and speed is obtained. The gate insulator structure of the field-effect transistor is SiO2/Si3N4/Ta/Ta2O5/Al2O3. The device is basically an enhancement mode metal–oxide–semiconductor field-effect transistor. The drain current ID of the device is measured at constant gate and drain voltages at 25 °C and found to be sensitive up to less than ∼1 ppmv moisture concentration. The response time of the sensor in ppmv level is less than 1 s. The device is also found to be very sensitive at higher RH levels and shows a linear dependency on RH. The response and recovery times of the sensor are 2 and 6 s, respectively.

Active food package incorporating an ethanol vapour-controlled release sachet has been known for its efficacies to delay microbial proliferation in fresh fruit and vegetable. High humidity inside the package could be utilized as a stimulus for conditional releases as a means to stabilize the sachet prior to being used. The present research was undertaken to investigate the effects of relative humidity on ethanol vapour release from the hydrophilic film-based sachet. The prototype 4-side sealed sachets were made of either ethylene vinyl acetate (EVA) or laminated film comprising EVA and Nylon/PE (designated as ENP). A gas chromatogram equipped with a flame-ionized detector (FID-GC) was employed to analyze ethanol vapour concentration levels released from both sachet types and accumulated in headspaces of sealed glass beakers having different relative humidity (RH) levels. For a given RH level, the concentrations in the headspaces containing the ENPbased sachets were lower than those containing the EVA-based sachets. Delays of ethanol vapour release up to 24 h were observed in the ENP-based sachet system, whilst these did not occur among EVA-based sachets. Both sachets could release ethanol vapour with faster rates and subsequently higher concentrations accumulated at the very high relative humidity level (90-99% RH), compared to lower RH levels (60-89% RH). However, the release rates and concentration levels accumulated in 60-75% RH were not different from those in 80-89% RH. Extents of water vapour uptake by films were relatively small when the films were kept at the lower RH levels, but these became exponentially increased when the RH levels were ≥90%RH. Experimental data on water vapour uptakes were well predicted by an exponential model (R2 0.92-0.99; and root mean square of errors (RMSE) 0.004-0.054). Overall, experiment findings indicate that the ENP film caused delayed ethanol vapour releases from the sachet. The relative humidity levels had significant effects on the releases from hydrophilic film-based sachets

The predatory mite Amblyseius swirskii (Athias-Henriot) (Acari: Phytoseiidae) is currently used as an efficient biological control agent of thrips, whiteflies and spider mites, which are economically damaging pests of ornamental plants and vegetable crops grown in greenhouses and fields worldwide. Currently, the effects of relative humidity (RH) and water availability on the optimal growth of A. swirskii are unknown. Here, we test the combined effects of different levels of RH (33%, 53%, 73% and 92%) and water availability on the development and reproduction of male and female A. swirskii feeding on the dried fruit mite, Carpoglyphus lactis (Linnaeus). While eggs failed to hatch at 33% RH, the survival rates of the immature stages at ≥ 53% RH increased solely in response to water availability and not due to changes in RH. Regarding growth and development, low RH extended the egg–adult duration and pre-oviposition period. We also found that the negative effects of low RH on fecundity were partially or completely eliminated when drinking water was available. For the life table parameters, the highest values of net reproductive rate (R0) and intrinsic rate of natural increase (r) were achieved at the highest RH and when drinking water was available. Overall, water availability mitigated the negative effect of low RH on female reproduction, and female development was more sensitive to water availability than male development. Lastly, a comparison of similar research on A. swirskii suggested that water availability and RH are more influential on r than food source or temperature.