Influence Of Humidity Research Articles

Effect of curing condition on mechanical properties and durability of alkali-activated slag mortar

While alkali-activated slag (AAS) has emerged as a promising alternative binder in construction engineering, a consensus on the optimal curing condition for this material has not been reached yet. It is well known that AAS can harden at ambient temperatures, but the influence of humidity on its properties remains poorly understood. Herein, we considered five curing conditions with different relative humidities (RH), including ambient/dry condition (RH=55 %), sealed condition (RH=80–95 %), fog condition (RH>95 %), water immersion condition (RH=100 %), and saturated limewater immersion condition (RH=100 %). Various properties have been examined, including flexural and compressive strengths, elastic modulus, shrinkage, pore structure, carbonation resistance, and freeze-thaw resistance of AAS mortars (AASM). Two types of activators, sodium hydroxide and sodium silicate (modulus at 1) solutions were used. The experimental results indicate that drying at early ages is detrimental to almost all the properties investigated. Sealed curing can deliver desirable mechanical properties and durability, but considerable shrinkage. Fog and water curings are highly effective at mitigating early shrinkage in AASM, but the problem of leaching adversely affects its long-term properties. Generally, limewater curing offers limited benefits compared to other high-humidity curing methods.

Impact of relative humidity on SARS-CoV-2 RNA extraction using Nextractor automated extraction system.

This study investigated the influence of relative humidity (RH) on the efficiency of SARS-CoV-2 RNA extraction using the Nextractor automated system. Experiments employing clinical samples demonstrated satisfactory sensitivity and reproducibility for RNA extraction at low humidity (below 50% RH). Conversely, extractions at high humidity (above 70% RH) resulted in complete failure of reverse transcription-polymerase chain reaction assays, with neither SARS-CoV-2 RNA nor the human RNase P gene (internal control) detected. Analysis suggested that residual ethanol, incompletely evaporating due to high humidity, acted as a potent polymerase chain reaction inhibitor in these samples. These findings highlighted the importance of maintaining optimal laboratory humidity (<50% RH) for reliable SARS-CoV-2 RNA extraction using the Nextractor system. Furthermore, laboratories should implement strategies such as regular humidity monitoring, staff training on humidity's impact, and system validation under specific humidity conditions to ensure accurate molecular diagnostic workflows for COVID-19 testing.

A scale-bridging model for proton exchange membrane fuel cells: Understanding interactions among multi-physics transports, electrochemical reactions and heterogeneous aging

The lifetime issues caused by catalyst degradation is one of the most critical challenges for the commercial application of proton exchange membrane fuel cells. However, the understanding concerning the interactions among transport, reaction, and catalyst degradation is inadequate for further durability enhancement. Herein, a scale-bridging model that couples a cell-scaled model to reveal the reactive transport process and a catalyst-scaled model to unveil Pt degradation is proposed to capture the degradation characteristics. It is found that the heterogeneous aging is observed in both the through-plane and channel-rib directions due to the enhanced mass loss near the membrane and the water accumulation under the rib, resulting in the mitigation of the core reaction region away from the membrane, thereby causing an increase in ohmic loss after cycles. More importantly, the local oxygen transport resistance increases with degradation, leading to a remarkable cell performance loss under high current density. Additionally, the influences of cell voltage load and inlet humidity on Pt degradation are also investigated. And the proposed gradient catalyst layer shows a significant mitigating effect on Pt degradation. This work reveals the degradation-performance interactions, which is conducive to design the high-performance fuel cell to prolong lifetime.

Influence of humidity on the performance of floating photovoltaic systems over ponds in a tropical urban environment

Influence of humidity on the performance of floating photovoltaic systems over ponds in a tropical urban environment

Influences of high temperature and humidity on vegetable-tanned leather

Leather artifacts, mainly composed of collagen and tanning agents, possess significant historical importance. However, external factors could lead to the aging of such artifacts during preservation. Therefore, it is crucial to examine the impact of various factors on leather aging. In order to know the effects of high temperature and humidity conditions on the changes of leather artifacts, the traditional vegetable tanning agents (chestnut, tara, quebracho, and mimosa) were used to tan the pickled sheepskins to prepare leather artifact model samples. The leather artifact model samples were aged for 0, 2, 4, 8, 16, and 32 days at 80°C and 40–80 % relative humidity (RH). The changes in appearance, structure and thermal stability of the vegetable-tanned leather samples under the synergistic impact of temperature and RH were analyzed using total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), chromatography, and scanning electron microscopy (SEM). The thermal degradation of the samples before and after being tanned with vegetable tanning agents was analyzed using thermal gravimetric analyzer (TGA) analysis. Furthermore, the shrinkage temperature (Ts), tensile strength and elongation at break of the samples were investigated during different aging periods. The study aims to provide valuable insights into the stability of leather artifacts during long-term storage, as well as guidance for their restoration and conservation.

A highly sensitive temperature sensor based on long period fiber grating coated with polymer-bilayer-membrane

This study introduces a highly sensitive temperature sensor based on long-period fiber grating (LPFG). The sensor is composed of a long period fiber grating covered by a higher RI (RI) layer of polyvinyl alcohol (PVA) and a lower RI layer of polydimethylsiloxane (PDMS). The PVA layer enables the sensor to operate in the mode transition region with high sensitivity, and the PDMS layer further enhances the temperature sensitivity owing to its high thermos-optic coefficient. In addition, the sensor can mitigate the influence of humidity due to the hydrophobic properties of PDMS. Experimental results show that the temperature sensitivity can achieve to 1232.3 pm/℃ within the range of 20℃-100℃ for an LPFG with a period of 363 μm coated with a 265 nm PVA layer and a 20 μm PDMS layer.

Determining the influence of relative humidity on the working parameters of a gas sensor based on zinc oxide

This paper investigates the dependence of operating parameters of a gas sensor based on zinc oxide obtained by the method of direct current magnetron sputtering. The production of gas sensor films was carried out using a VUP-5M vacuum unit with an original material-saving magnetron. The study of the dependence of the working parameters of the gas sensor was carried out under standard conditions. It was found that with increasing humidity, the electrical resistance of the gas sensor decreases and, accordingly, the sensitivity to the target gas decreases. A significant reaction of the gas sensor to an increase in humidity was observed in the range of 65–80 % relative humidity. The mechanism of influence of relative humidity on the sensitivity of a gas sensor based on ZnO was investigated. The change in resistance of the gas sensor is caused by trapped electrons on adsorbed oxygen molecules on the surface of the sensitive layer. The capture of electrons from the conduction zone leads to bending of the conduction zone and an increase in the space charge zone, respectively, to a change in the resistance of the sensitive layer of the gas sensor. In the atmosphere, when O2 molecules are adsorbed on the ZnO surface, they remove an electron from the conduction band. The reaction of oxygen adsorbed on the ZnO surface with reducing gases and the replacement of adsorbed oxygen with other molecules changes the bending of the conduction band and reduces the area of space charge. Adsorption of water on the surface of zinc oxide occurs according to the dissociation mechanism, which consists in the adsorption of steam molecules or hydroxyl groups with the subsequent displacement of previously adsorbed oxygen and free electrons and, accordingly, leads to a decrease in the sensitivity of the gas sensor. In addition, the adsorption of water vapor (H2O) molecules leads to less chemisorption of oxygen species on the ZnO surface due to the reduction of the surface area, which is responsible for the sensor response. Approaches to reduce the influence of relative humidity on the sensitivity of a gas sensor based on zinc oxide have been proposed

Analysis of the Energy-Saving Effect of a Novel Central Air-Conditioning System with an Internal Heat Exchanger in Summer

In this paper, a novel central air-conditioning system with an internal heat exchanger is proposed and analyzed for its energy-saving effect. Two frequently used systems are chosen as the reference systems, i.e., a conventional system with a sensible heat exchanger (Reference System I) and a conventional system with a total heat exchanger (Reference System II). Analysis models are built to simulate the performance of the system. The energy-saving effects of the proposed system and the two reference systems under different conditions are theoretically calculated using a case-studied shopping mall in Nanjing, China. The results show that the influence of indoor relative humidity (RH) on the energy-saving effect is much greater than that of the indoor design temperature. Indoor design parameters have a greater impact on energy saving than outdoor design parameters. Under the studied conditions, the maximum energy-saving rates of the proposed system, Reference System I, and Reference System II, are 52.7%, 2.3%, and 12.1%, respectively. With the decrease in fresh-air ratio from 70% to 20%, the difference in energy-saving rates between the proposed system and Reference System II (Reference System I) can increase from 5% to 23% (15% to 30%). Therefore, the proposed system has obvious energy-saving potential and advantage, especially under the condition of a lower fresh-air ratio.

A new photoionization-induced substitution reaction chemical ionization time-of-flight mass spectrometry for highly sensitive detection of trace exhaled ethylene

Highly sensitive and rapid detection of ethylene, the smallest alkene of great significance in human physiological metabolism remains a great challenge. In this study, we developed a new photoionization-induced substitution reaction chemical ionization time-of-flight mass spectrometry (PSCI-TOFMS) for trace exhaled ethylene detection. An intriguing ionization phenomenon involving a substitution reaction between the CH2Br2+ reactant ion and ethylene molecule was discovered and studied for the first time. The formation of readily identifiable [CH2Br·C2H4]+ product ion greatly enhanced the ionization efficiency of ethylene, which led to approximately 800-fold improvement of signal intensity over that in single photon ionization mode. The CH2Br2+ reactant ion intensity and ion-molecule reaction time were optimized, and a Nafion tube was employed to eliminate the influence of humidity on the ionization of ethylene. Consequently, a limit of detection (LOD) as low as 0.1 ppbv for ethylene was attained within 30 s at 100 % relative humidity. The application of PSCI-TOFMS on the rapid detection of trace amounts of exhaled ethylene from healthy smoker and non-smoker volunteers demonstrated the satisfactory performance and potential of this system for trace ethylene measurement in clinical diagnosis, atmospheric measurement, and process monitoring.

A Method for Predicting Wear Behaviours of Roller Linear Guides Under the Influence of the Relative Humidity and Ambient Temperature

The wear of roller linear guides (RLG) has a direct impact on the tooling precision of CNC machine tool. Wear depends on working conditions: load P, speed V, work environment which includes relative humidity RH and ambient temperature T. In this paper the mathematical regression function describes the relationship between the wear amount U of RLG with the three factors P, RH and T built on the basis of experimental research. The results show that the wear regression function U has an exponential form, which is consistent with experiments about the influence of climatic environment. It describes the simultaneous impact of three factors P, RH, T that affect wear of CNC machine tool rolling guide. With Vietnam's hot and humid environmental conditions, relative humidity RH% = 51 - 99%, temperature T = 15 - 450C, and load P = 2 - 6kgf, the influence on rolling guide wear of normal load P is 2 times the humidity RH% and about 3.8 times that of temperature T. Therefore, it is possible to predict the change in wear amount according to two environmental factors when loading P at certain values.

Stability of giant dielectric properties in co‐doped rutile TiO2 ceramics under temperature and humidity

AbstractThis research investigated the influence of temperature and humidity on the giant dielectric (GD) properties of 1% indium tin oxide and 1% Ta2O5 co‐doped TiO2 ceramics sintered at different temperatures. A single phase of rutile TiO2 was obtained in all sintered samples. The mean grain size increased with higher sintering temperatures, resulting in ceramics with a relative density exceeding 98%. A uniform dispersion of dopants and major elements was achieved. Remarkably, the dielectric constant increased significantly from 2 × 103 to 3.7 × 104 with a rising sintering temperature, primarily due to the enlarged grain size. Concurrently, the authors observed low loss tangents, ranging from tanδ≈0.016 to 0.024 at 1 kHz. Slight variations in the dielectric constant were observed with temperature from room temperature up to 210°C, while maintaining remarkably low tanδ. The GD properties were attributed to space charge polarisation at internal interfaces and defect dipoles. Further research explored the impact of environmental conditions on dielectric properties. Remarkably, the ceramics exhibited minimal capacitance variations of less than 10% within the relative humidity range of 30%–95% and temperatures from 15 to 85°C, indicating excellent dielectric stability.

A new approach for selective and ultrasensitive ammonia sensors by CuBr encapsulation in a mesoporous thin film for potential metabolic acidosis non-invasive monitoring

Ammonia (NH3) can be considered as a chronic kidney disease bioindicator. The detection of skin emitted ammonia would allow a non-invasive medical monitoring of patients. Here, we develop a highly-sensitive and selective room-temperature ammonia microsensor based on copper-bromide (CuBr). The CuBr is impregnated in a mesoporous layer prepared by sol-gel synthesis and deposited by dip-coating on interdigitated platinum electrodes. The sensing performances are evaluated at 34 °C in dry air for short exposures (2 min) to ammonia. The sensor exhibits very high response (Rg/Ra of 4.5 for 200 ppb) with rapid recovery time and a very good selectivity. Moreover, the influence of humidity and temperature on the sensor performances are evaluated. The reported results demonstrate the possibility of developing an ultrasensitive gas sensor by a simple and low-cost approach consisting of the impregnation of the sensitive element in a mesoporous thin film.

Influence of relative humidity on carbon sequestration and crystal morphology of air lime: A sustainable building material

This study investigated the carbon sequestration potential of air lime by carbonation in two different relative humidity conditions. The carbonation rate and amount of carbon dioxide captured were quantified using weight gain and various analytical techniques. Samples cured in high relative humidity showed almost complete carbon capture by sequestering 94.8 % of carbon dioxide from atmospheric air within 56 days, with calcite crystal formation and a high crystallinity index. Similarly, samples cured in low relative humidity conditions showed slightly less carbonation around 83.8 % with different calcium carbonate polymorphs like aragonite and vaterite, along with amorphous calcium carbonate. Results demonstrated that carbonation of lime is a promising technology for carbon capture and utilization in buildings as non-load bearing mortars or plasters and could be used to reduce carbon dioxide levels in the atmosphere.

The influence of activity patterns and relative humidity on particle resuspension in classrooms

This paper investigates the impact of children's recess activity patterns on particulate matter (PM) resuspension in indoor environments, highlighting the complex, multi-dimensional nature of these activities and their interaction with environmental parameters. Despite the recognized role of indoor human activity in PM resuspension, research specifically addressing the effects of children's movements has been sparse. Through experimental scenarios that account for the characteristics of student activities, such as movement speed, trajectory, the number of participants, aisle widths, and varying humidity levels, this study uncovers significant differences in PM resuspension rates. It reveals that not only do movement speed and trajectory have a profound impact, but also the interaction between humidity and these factors plays a critical role, especially under lower humidity conditions. Additionally, the study demonstrates how the combination of people density and spatial configurations can significantly influence resuspension rates. The findings offer valuable insights for designing strategies to mitigate particle pollution in classrooms and similar indoor environments.

Relationship between indoor and outdoor temperature and humidity in a residential building in Central Europe

Relative humidity and temperature in indoor spaces are two important environmental factors that not only determine the behaviour and well-being of building occupants but also influence airborne transmission of respiratory diseases in closed spaces. While recent studies have examined how well indoor conditions relate to outdoor ambient weather, most studies on weather-related health effects still use a single central site monitor such as a weather station since outdoor values are more convenient to measure. However, the correlation between indoor and outdoor values is not always straightforward. Our case study explores the relationships between indoor and outdoor temperature and humidity in a residential building apartment in a temperate climate in Central Europe. Measurements performed over the period of one year allow for a detailed comparison and analysis of correlations between both daily averages as well as daily profiles of indoor and outdoor variables. The results of this case study add further evidence to the observations that day-to-day variation in indoor temperature and relative humidity are not well-represented by outdoor measurements. It further adds to the growing body of data on indoor environmental variables and should thus prove useful in studies aiming to determine the influence of relative humidity and temperature on indoor transmission of airborne diseases as well as in studies examining the influence of these two variables on the well-being of building occupants.

A simplified fatigue model for CFRP-strengthened RC beams under the coupling action of a hot–wet/saline environment and cyclic loading

Reinforced concrete (RC) structures in subtropical coastal areas are subjected to the combined influences of temperature, humidity, and salt exposure. Previous studies on the fatigue failure of fiber-reinforced polymer (FRP)-RC structures did not consider the coupling effect of the environment and loading. In this study, a simplified hot–wet/saline environmental fatigue model was developed to consider the linear influence of environmental parameters, including temperature, humidity, and salinity. Then, a closed environmental box was self-designed to provide the temperature–saline environment. By simulating a subtropical coastal environment with typical salinity levels (0, 3, and 5 wt% NaCl) and temperatures (10, 35, and 50 °C), fatigue tests were conducted on 38 typical carbon fiber-reinforced polymer–RC beams. In assessing the simplified model’s predictive accuracy, the average errors for estimating the fatigue limits and lives in the validation groups with or without saline conditions were 4.1 % and 33.7 %, respectively. The simplified model indicated that higher unit temperature and humidity similarly reduced the fatigue limit and that higher salinity decreased the fatigue limit by approximately 7.2 times greater than temperature or humidity. This research provides valuable insights into the strength design and life prediction of RC structures in the offshore or subsea regions of subtropical coastal areas.

Epidemic Characteristics and Meteorological Risk Factors of Hemorrhagic Fever With Renal Syndrome in 151 Cities in China From 2015 to 2021: Retrospective Analysis.

Hemorrhagic fever with renal syndrome (HFRS) continues to pose a significant public health threat to the population in China. Previous epidemiological evidence indicates that HFRS is climate sensitive and influenced by meteorological factors. However, past studies either focused on too-narrow geographical regions or investigated time periods that were too early. There is an urgent need for a comprehensive analysis to interpret the epidemiological patterns of meteorological factors affecting the incidence of HFRS across diverse climate zones. In this study, we aimed to describe the overall epidemic characteristics of HFRS and explore the linkage between monthly HFRS cases and meteorological factors at different climate levels in China. The reported HFRS cases and meteorological data were collected from 151 cities in China during the period from 2015 to 2021. We conducted a 3-stage analysis, adopting a distributed lag nonlinear model and a generalized additive model to estimate the interactions and marginal effects of meteorological factors on HFRS. This study included a total of 63,180 cases of HFRS; the epidemic trends showed seasonal fluctuations, with patterns varying across different climate zones. Temperature had the greatest impact on the incidence of HFRS, with the maximum hysteresis effects being at 1 month (-19 ºC; relative risk [RR] 1.64, 95% CI 1.24-2.15) in the midtemperate zone, 0 months (28 ºC; RR 3.15, 95% CI 2.13-4.65) in the warm-temperate zone, and 0 months (4 ºC; RR 1.72, 95% CI 1.31-2.25) in the subtropical zone. Interactions were discovered between the average temperature, relative humidity, and precipitation in different temperature zones. Moreover, the influence of precipitation and relative humidity on the incidence of HFRS had different characteristics under different temperature layers. The hysteresis effect of meteorological factors did not end after an epidemic season, but gradually weakened in the following 1 or 2 seasons. Weather variability, especially low temperature, plays an important role in epidemics of HFRS in China. A long hysteresis effect indicates the necessity of continuous intervention following an HFRS epidemic. This finding can help public health departments guide the prevention and control of HFRS and develop strategies to cope with the impacts of climate change in specific regions.

Effect of the porous structure on the hygrothermal vibration analysis of functional graded nanoplates using nonlocal high-order continuum plate model

This study delves into the thermomechanical vibration behavior of functionally graded porous nanoplates under extreme thermal temperature and humidity conditions. The equation of motion of the nanoplate was derived using advanced theories in elasticity and deformation. The nanoplate consists of metal (SUS304) on the bottom surface and ceramic (Ni3S4) on the top surface, with the material distribution changing according to the power law across the plate thickness. The nanoplate was modeled with uniform and symmetric distributions of porosity reaching as high as 60%. Upon incorporating the thermal and moisture loads from the humid surroundings into the equations of motion derived from Hamilton's principle, the equations were solved using Navier's method and simplified to the eigenvalue equation. Analyzed within a broad framework are the thermomechanical vibration behavior of the nanoplate, temperature impact, humidity influence, porosity and its distribution, material grading parameter effects, and nonlocal integral elasticity effects. Observations indicate that variations in thermal temperature, humidity, and nonlocal parameters can lower the thermomechanical vibration frequency of the nanoplate, whereas porosity has the opposite effect. The effects mentioned are influenced by factors, such as the porosity ratio, porosity distribution, material ratios, and the size of the nonlocal parameter in the plate. The primary objective of this work is to uncover the nonlinear frequency response of nanoplates with high porosity in conditions characterized by high temperature and humidity.

Incorporation of ground mustard seeds in an active packaging film: structural properties and controlled release of allyl isothiocyanate

SummaryGround mustard seeds can be incorporated into a packaging film material to have a controlled release of allyl isothiocyanates (AITC). However, the properties of film material loaded with ground mustard seeds need to be evaluated, since they might influence the release of AITC from the film materials. This study aimed to assess properties, including surface morphology, spectral analysis, crystallinity, the moisture‐related, thermal and mechanical properties, of the film materials incorporated with the ground seeds and the release of antimicrobial compounds. Furthermore, the effects of relative humidity on AITC release in the headspace were investigated. The results showed that incorporating a larger quantity of ground mustard seeds resulted in the quicker release of AITC due to direct exposure to moisture, as indicated by higher concentrations observed in the headspace. Meanwhile, a smaller quantity of ground seeds added to the film maintained the thermal properties of the materials until 100 °C, resulting in significantly better moisture‐related properties and higher mechanical strength in terms of tensile strength, elastic modulus, and strain at break. However, the smallest ratio (1:5) showed no release of AITC into the packaging headspace at 75% and 100% RH. Furthermore, the relative humidity led to the release of more AITC in the headspace, which is potentially applied for high‐moisture food products. Based on the influence of relative humidity on AITC concentrations, the mechanism of AITC release from the film materials is proposed, describing the AITC diffusion from ground mustard seeds, film, and headspace.

Influence of Humidity on the Dielectric Properties of Two-Dimensional Microsized Molybdenum Disulfide Powders

Influence of Humidity on the Dielectric Properties of Two-Dimensional Microsized Molybdenum Disulfide Powders