Influence Of Ambient Humidity Research Articles

Humidity-tolerant and highly sensitive gas sensor for hydrogen sulfide based on WO3 nanocubes modified with CeO2.

The influence of ambient humidity on the gas-sensing characteristics of metal oxide semiconductors has been one of the greatest obstacles for gas-sensing applications. In this paper, the pure WO3 and CeO2-modified WO3 nanocubes were prepared by a simple hydrothermal method, and their gas-sensing characteristics in dry and humid atmospheres were investigated. The results show that CeO2/WO3 demonstrated excellent gas-sensing properties toward H2S with high sensitivity and high selectivity at 115 °C. Noteworthy, the humidity independence of the CeO2/WO3 increased compared to the WO3. The response retentions over the whole humidity range of the CeO2/WO3-6 and CeO2/WO3-15 sensors were 70.3, and 76%, respectively, which were much higher than the WO3 sensor (17.9%). The gas-sensing mechanism of CeO2-modified WO3 is discussed based on the gas sensitivity properties. The obtained results provide a promising route to enhance the anti-humidity properties of metal oxide semiconductor gas sensors.

Influence of temperature and humidity coupling on rutting deformation of asphalt pavement

Abstract In this article, ABAQUS finite-element software is used to establish an asphalt pavement structure model under high-temperature environment in summer. The changes in the temperature field and moisture concentration field of asphalt pavement are studied under the condition of 1-day continuous temperature change. The creep model is used to analyse the influence of ambient temperature and humidity on the rutting deformation of asphalt pavement. The results show that the maximum temperature of asphalt pavement can reach 60°C in the high-temperature environment in summer. The temperature accumulation effect causes the temperature of the middle and lower layers to increase by approximately 10°C, which easily induces rutting. Ambient humidity has a great influence on the change in moisture concentration in the upper layer. Considering the influence of ambient humidity in the high-temperature environment, the rut depth increases by 67%.

Evaporation of alcohol droplets on surfaces in moist air

Droplets of alcohol-based formulations are common in applications from sanitizing sprays to printing inks. However, our understanding of the drying dynamics of these droplets on surfaces and the influence of ambient humidity is still very limited. Here, we report the drying dynamics of picoliter droplets of isopropyl alcohol deposited on a surface under controlled humidity. Condensation of water vapor in the ambient environment onto alcohol droplets leads to unexpectedly complex drying behavior. As relative humidity (RH) increases, we observed a variety of phenomena including enhanced spreading, nonmonotonic changes in the drying time, the formation of pancake-like shapes that suppress the coffee-ring effect, and the formation of water-rich films around an alcohol-rich drop. We developed a lubrication model that accounts for the coupling between the flow field within the drop, the shape of the drop, and the vapor concentration field. The model reproduces many of the experimentally observed morphological and dynamic features, revealing the presence of unusually large spatial compositional gradients within the evaporating droplet and surface-tension-gradient-driven flows arising from water condensation/evaporation at the surface of the droplet. One unexpected feature from the simulation is that water can evaporate and condense concurrently in different parts of the drop, providing fundamental insights that simpler models based on average fluxes lack. We further observed rim instabilities at higher RH that are well-described by a model based on the Rayleigh-Plateau instability. Our findings have implications for the testing and use of alcohol-based disinfectant sprays and printing inks.

Design and analysis of integrated environmental control system for Plateau cold chain transport vehicles

Plateaus, one of the most important terrain types in China, contain high-quality agricultural and livestock resources. However, due to their natural conditions, they host major deficiencies in cold chain logistics. Existing studies have focused on improving the temperature regulation capabilities of cold chain vehicle refrigeration or air conditioning systems, but have neglected the unique low-pressure environment faced by the Plateau cold chain transport vehicles. Using zoning design, air and vapor cycle refrigeration technologies, this study proposed a bootstrap-type integrated environmental control system (BIECS) and simple-type integrated environmental control system (SIECS) to realize vehicle “micro-environmental control.” The analytical solution of the thermal characteristics of the system was obtained based on the scaling-endoreversible thermodynamic analysis model. Moreover, the influence of ambient humidity on the thermal performance of the system was evaluated based on the enthalpy method. According to the typical working conditions, the system performances using different refrigerants, R404A, R448A, and R452A, were analyzed at different trailer temperatures, cooling capacities, and altitudes. Our results showed that, under the same design requirements, the coefficient of performance (COP) of the BIECS was slightly higher than that of the SIECS. Higher the trailer temperature and cooling capacity, higher is the COP of the system. Comparing the three refrigerants under the same working conditions, compared with R404A, the COP of the BIECS and SIECS increased by 13.4% and 10.9%, respectively, using R484A, and increased by 6.1% and 5.0%, respectively, using R452A. The performance of the systems that used R448A was the best. The system could ensure a 2.4-km cab pressure altitude at an ambient altitude of 5 km, but the COP could decrease by 31.8–35.6%, compared to that on the plains. This study provides and comprehensively evaluates a new technical solution for the environmental control of Plateau cold chain transportation vehicles. It also provides comprehensive health protection measures for drivers and technical support for the promotion and development of Plateau cold chains.

Influence of ambient humidity on the adhesion and damage behavior of wheel–rail interface under hot weather condition

A wheel/rail system is an open system, where the operating environment factors, such as atmospheric humidity, temperature, and oxidation behavior, are subject to change. This study conducts experiments on a twin-disc test rig with a climate chamber to examine the effect of ambient humidity on adhesion and damage between the wheel and rail interface under hot weather conditions. Results indicate that humidity has a remarkable effect on the adhesion behavior of a wheel–rail rolling contact interface. Under low humidity levels, fatigue wear is predominant, abrasive wear becomes increasingly serious with an increase in humidity, oxide wear debris acts as abrasive particles and accelerates the wear process. Under high humidity levels, a friction-reducing layer is formed, and the rollers are protected from excessive wear. Adhesive wear is the main damage mechanism in addition to oxidative wear. Raising the humidity level helps the rollers to avoid excessive wear. However, high humidity level is unconducive to the safe operation of trains because high humidity and a high heat environment promotes the formation of tribochemical products which are a mixture of iron oxide and water molecules and lead to a great decrease in the adhesion between wheel and rail.

The role of oxygen vacancies on SnO2 surface in reducing cross-sensitivity between ambient humidity and CO: A first principles investigation

The sensing properties of SnO2 based CO gas sensors can be affected by ambient humidity and oxygen pressure. In this study the effect of oxygen vacancy along with the adsorption mechanism of H2O and CO on SnO2 (110) surface has been investigated by performing density functional theory (DFT) calculations. The influence of ambient humidity has been taken into consideration in order to better understand the CO sensing mechanism in SnO2 based gas sensors. Molecular and dissociative adsorption of H2O on both stoichiometric and oxygen deficient surface were simulated. Adsorption energies, Bader charge analysis and the projected density of states were investigated by employing electronic structure calculations. The findings show that CO adsorption in most cases is less favorable in the presence of H2O and on the reduced SnO2 surface. However, oxygen vacancies provide more sites to adsorb H2O molecules to compensate the humidity cross-interference. Furthermore, CO to CO2 conversion along with dissociative H2O adsorption on the vacancy of oxygen site presents the highest charge transfer and very strong adsorption energy among other adsorption configurations. These findings provide a guideline for fabricating more efficient CO sensors.

Influence of ambient humidity on the stability of negative bias illumination for amorphous indium gallium zinc oxide thin film transistors

Influence of ambient humidity on the stability of negative bias illumination for amorphous indium gallium zinc oxide thin film transistors

Tetrahydroxyphenyl porphyrin membrane: a high-sensitivity optical waveguide gas sensor for NO2 detection

In this study, 5,10,15,20-(4-hydroxyphenyl) porphyrin (THPP) was used as an optical waveguide (OWG) sensing material to detect several harmful acidic gases and volatile organic compounds. With this material, the sensor showed high selectivity and sensitivity to NO2. First, a OWG sensor based on THPP was prepared using the spin-coating method. Next, the absorbance changes in the porphyrin film before and after interaction with NO2 gas were analyzed using an ultraviolet-visible spectrophotometer. A 670 nm detection light source was selected for testing the OWG detection system; the optimum conditions were studied, where the lowest concentration detected by the sensor was 10 ppb. The film thickness (190 nm) was measured using scanning electron microscopy (SEM). Thereafter, the gas-sensing mechanism was further investigated through SEM, IR, and x-ray diffraction. Finally, the influence of ambient humidity on the sensor was analyzed. The results showed that ambient humidity can be neglected. The transducer exhibited uncomplicated fabrication and easy portability, and the detection process of OWG could be conducted at ambient temperature and resist electromagnetic interference.

Friction vs. Area Scaling of Superlubric NaCl-Particles on Graphite

Structural lubricity is an intriguing tribological concept, where extremely low friction is anticipated, if two surfaces in relative motion do not share the same lattice structure and consequently instabilities originating from interlocking surface potentials are strongly reduced. Currently, the challenges related to the phenomenon of structural lubricity are considered to be twofold. On one hand, experimental systems suitable for showing structural lubricity must be identified, while at the same time, it is also crucial to understand the intricate details of interface interaction. Here, we introduce a new material combination, namely NaCl-particles on highly oriented pyrolithic graphite (HOPG), where the nanoparticles coalesce under the influence of ambient humidity. Our experiments reveal that the interfacial friction can be described by the concept of structural lubricity despite the seemingly unavoidable contamination of the interface. By systematically analyzing the friction versus area scaling, this unlikely candidate for structural lubricity then shows two separate friction branches, with distinct differences of the friction versus area scaling. The exact tribological behavior of the nanoparticles can ultimately be understood by a model that considers the influence of nanoparticle preparation on the interface conditions. By taking into account an inevitable water layer at the interface between particle and substrate that can exist in different crystalline configurations all friction phenomena observed in the experiments can be understood.

Influence of Ambient Humidity on the Conductivity Enhancement of PEDOT:PSS Films during the Acetic Acid Treatment

In this work, well-controlled ambient humidity can adjust the conductivity of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) films during an acetic acid rinse. The conductivity of PEDOT:PSS films can be dramatically enhanced by optimizing post-treatment ambient humidity. The conductivity of PEDOT:PSS films increase from 0.33 S/cm for the pristine to 1090 S/cm at relative humidity (RH) of 60% while that of PEDOT:PSS films is only 5.04 S/cm at H2O < 1 ppm. The improvement conductivity should be attributed to enhanced phase segregation, removing of some PSS chains from PEDOT:PSS and reorganization of PEDOT chains at higher RH. This facile solvent-treated route provides a promising transparent electrode fabrication method to replace ITO electrode in organic photovoltaics (OPVs).

Surface Electrical Properties of Fluorinated Epoxy Resin and Influence of Ambient Humidity

As-prepared epoxy resin samples were surface fluorinated using a F2/N2 mixture. The fluorination resulted in a remarkable increase in surface conductivity of the epoxy sample by over three orders of magnitude. Corona charges deposited on the fluorinated surface could not be stored even at room temperature. Obvious dependence of surface conductivity and steady state surface current on ambient humidity was found for the fluorinated sample. ATR-IR analysis and SEM imaging of surface and cross-section demonstrated substantial changes in surface layer chemical composition and morphology due to the fluorination, which are responsible for the changes in surface electrical properties.

Effect of humidity on the a.c. impedance of CH3NH3SnCl3 hybrid films

Impedance spectroscopy measurements show that complex conductivity of thermally ablated CH3NH3SnCl3 films is strongly enhanced when humidity increases. Coplanar two-electrode test devices are modeled through an equivalent circuit comprising one resistance and two constant phase elements. It is shown that the influence of ambient humidity is mainly resistive. The dynamic responses of the devices to humidification/dehumidification cycles point out that the a.c. current varies by more than three orders of magnitude when humidity is varied between dry air and 80% relative humidity. The rise times are few hundred seconds while fall times are as short as few tens of seconds. This observation suggests that impedance variations are determined by mechanisms involving loosely bound water molecules physisorbed at the surface of the hybrid film. The results obtained are discussed in terms of protonic conduction.

A Mass-Sensitive Approach for the Detection of Anaesthetic Xenon

Quartz crystal microbalances (QCMs) were utilized for the detection of the noble gas xenon (Xe) by combining them with different recognition layers such as permethylated calixarenes (tetramethyl-tert-butylcalix[4]arene (Cal4Me), hexamethyl-tert-butylcalix[6]arene (Cal6Me)), and polyurethanes, with covalently embedded Cal4OH (Poly4Cal), or Cal6OH (Poly6Cal). A third type of sensitive material is synthesized from polyacrylic acid (PAA) and polyvinyl alcohol (PVA) and utilized as a sensitive coating. The results demonstrate that the Cal4Me layer gives higher response towards Xe, while, by the use of a second uncoated QCM channel, the influence of ambient humidity could be nearly completely compensated by signal subtraction. Moreover, the Cal4Me sensor shows excellent reversibility and rapid response time, providing a potentially reliable way to determine Xe during anaesthesia.

Influence of ambient humidity on the surface conductivity of hydrogenated diamond

The enhancement of the electrical conductivity of hydrogen-terminated diamond surfaces due to the adsorption of various chemical species represents a challenging problem and has a high application potential as well. In the transfer doping model of Maier et al. the presence of a water layer that forms spontaneously in moist atmospheres on any surface plays a crucial role. Hence, in the present contribution we have focused our attention on the influence of the relative humidity (RH) on the surface conductivity. In order to perform conductivity measurements in a wet atmosphere an original technique eliminating leakage effects due to adsorbed water was developed. The conductivity was measured at room temperature for RH between 2% and 100%. Despite a rather weak dependence on RH, three well distinguished regions can be identified in the conductivity as a function of RH. Not pretending to offer a first-principles account for this behaviour, a phenomenological explanation of the data is given.

Thriving in an arid environment: High prevalence of avian lice in low humidity conditions

Abiotic factors have been reported to cause variation in parasite pressure among host populations, but such relationships have not been studied in detail, and conflicting evidence exists about the nature of these relationships. Here we study within- and between-population variation in chewing lice parasitization in an arid bird species, the Trumpeter finch (Bucanetes githagineus), and the influence of ambient humidity on parasite load. We found a high prevalence of 2 chewing lice even in particularly dry years and a positive effect of humidity on prevalence at a monthly scale. Nonetheless, our results clearly reveal that lice can become abundant at low ambient humidity conditions and that birds in arid environments are not necessarily under lower ectoparasitic pressure than birds in humid regions. We suggest that lice may adapt their life cycle to overcome the most critical period by synchronizing the more resistant phase (eggs) to the period when relative humidity is lowest (i.e., summertime). We stress that studies on the effect of ecological factors on host-parasite relationships should consider detailed aspects of the life cycle of the latter and the main biological traits of the different stages of the parasites.

Nanocones on (a-C:H):Si composite films: Thermal stability, growth dynamics and electrical properties

Some aspects of Scanning Probe Microscopy (SPM) — based nanostructuring of (a-C:H):Si composite films, including (i) correlations between geometrical and electrical properties of modified regions during SPM actions, (ii) deviations of the nanocone shape under heat treatment, and (iii) the influence of ambient humidity on the nanocone growth, were studied. The investigations revealed an initial period of SPM actions, during which no modification of the film surface was registered. On finishing this period, the film conductivity was found to rapidly decrease, and just at this moment the nanocone growth started. The formed nanocone kept its shape after heat treatments up to 700 °C under vacuum conditions of ∼ 100 Pa. It was also found that the higher the humidity, the faster was the nanocone growth. The latter was accompanied by the formation of a corrugated pedestal. The nature of the observed phenomenon is discussed.

Influence of ambient humidity on the current delivered by air-vented ionization chambers revisited

The influence of ambient humidity on the current delivered by a vented ionization chamber has been re-investigated. A Nucletron 077.091 well-type chamber together with a 192Ir HDR brachytherapy source was enclosed in a climatic test chamber and the current was recorded for various humidity values. Great care has been taken for the design of the experimental setup in order to obtain reliable measurements of currents and humidity values inside the chamber active volume. A ±0.35% linear variation of the measured currents has been observed over a common range of humidities. This result is larger than the expected variation. No formal explanation of such a discrepancy has been found yet, however the present results could lead to a set of recommendations.

Sputtered and screen-printed metal oxide-based integrated micro-sensor arrays for the quantitative analysis of gas mixtures

Either by screen-printing or sputtering, sensitive layers of tin oxide were deposited on silicon micromachined substrates (four-element integrated microarrays). The procedures allow the deposition of sensing layers before membranes have been etched, which leads to gas micro-sensors with an excellent fabrication yield. The response of the different microarrays to ethanol, acetone and ammonia vapours and their binary mixtures was studied. The influence of ambient humidity was also investigated. By using an integrated array of four integrated microsensors operated at two different temperatures and a fuzzy ARTMAP neural network, it was possible to simultaneously identify and quantify the different species (success rate was 100%). These results confirm the viability of the techniques introduced to obtain micromachined sensors suitable for battery-powered gas/vapour monitors.

The repeatability of friction and wear results obtained from unlubricated reciprocating sliding tests

AbstractLaboratory tests can help in the analysis of tribological failures of elements, and improve tribo‐systems by choosing appropriate materials. In order to characterise the friction and wear behaviour of candidate materials, various different test methods have been developed in the past and are still in use. One such method is the reciprocating sliding of a ball against a disc.In the work reported here, the repeatability of friction and wear results was evaluated with ten tests under identical conditions with a steel (100Cr6) or alumina (Al2O3) ball against a steel (100Cr6) disc under unlubricated conditions at room temperature. The influence of ambient humidity on friction and wear behaviour was determined in three additional tests in dry and in moist air, respectively. The repeatability of friction coefficient in normal air was better than 5% for alumina/100Cr6 and 12% for 100Cr6/100Cr6, while the repeatability of volumetric wear was slightly better than 10% for alumina/steel, and slightly worse than 10% for steel/steel.For both couples the coefficient of friction is lowest in moist air and about 50% higher in dry air. The coefficient of wear is also least in moist air and higher by a factor of 3(5) in dry air for tests with a 100Cr6 (alumina) ball.

Influence of Ambient Humidity and Root Zone Shielding on Tomato Seedling Growth1

Abstract Low ambient humidity reduced growth and increased H2O consumption by seedlings of tomato (Lycopersicon esculentum Mill. cv. Kokomo) grown in well-watered peat pellets. Shielding the root medium with a thin, flexible plastic sleeve prevented growth reduction, which appeared to be largely the result of root zone evaporative cooling. Low inlet relative humidity (5%) depressed root temperature of unjacked peat pellets –7° to –9°C. Root zone shielding reduced the temperature depressions of both humidity treatments to –4°. Of various growth parameters observed, root growth was most dramatically improved by shielding at either level of humidity.