Effects Of Changes In Humidity Research Articles

Integrative analysis of yeast colony growth

Yeast colonies are routinely grown on agar plates in everyday experimental settings to understand basic molecular processes, produce novel drugs, improve health, and so on. Standardized conditions ensure these colonies grow in a reproducible fashion, while in nature microbes are under a constantly changing environment. Here we combine the power of computational simulations and laboratory experiments to investigate the impact of non-standard environmental factors on colony growth. We present the developement and parameterization of a quantitative agent-based model for yeast colony growth to reproduce measurements on colony size and cell number in a colony at non-standard environmental conditions. Specifically, we establish experimental conditions that mimic the effects of humidity changes and nutrient gradients. Our results show how colony growth is affected by moisture changes, nutrient availability, and initial colony inoculation conditions. We show that initial colony spread, not initial cell number have higher impact on the final size and cell number of colonies. Parameters of the model were identified by fitting these experiments and the fitted model gives guidance to establish conditions which enable unlimited growth of yeast colonies.

Effects of Strain Differences, Humidity Changes, and Saliva Contamination on the Inactivation of SARS-CoV-2 by Ion Irradiation.

One of the methods to inactivate viruses is to denature viral proteins using released ions. However, there have been no reports detailing the effects of changes in humidity or contamination with body fluids on the inactivation of viruses. This study investigated the effects of humidity changes and saliva contamination on the efficacy of SARS-CoV-2 inactivation with ions using multiple viral strains. Virus solutions with different infectious titers were dropped onto a circular nitrocellulose membrane and irradiated with ions from 10 cm above the membrane. After the irradiation of ions for 60, 90, and 120 min, changes in viral infectious titers were measured. The effect of ions on virus inactivation under different humidity conditions was also examined using virus solutions containing 90% mixtures of saliva collected from 10 people. A decrease in viral infectivity was observed over time for all strains, but ion irradiation further accelerated the decrease in viral infectivity. Ion irradiation can inactivate all viral strains, but at 80% humidity, the effect did not appear until 90 min after irradiation. The presence of saliva protected the virus from drying and maintained infectiousness for a longer period compared with no saliva. In particular, the Omicron strain retained its infectivity titer longer than the other strains. Ion irradiation demonstrated a consistent reduction in the number of infectious viruses when compared to the control across varying levels of humidity and irradiation periods. This underscores the notable effectiveness of irradiation, even when the reduction effect is as modest as 50%, thereby emphasizing its crucial role in mitigating the rapid dissemination of SARS-CoV-2.

Study on spore release of Polytrichum commune Hedw. var. commune by synergetic effects of sub-hygroscopic movement and wind.

The effect of humidity change on spore release of the Nematodontae Polytrichaceae has never been tested experimentally. Similarly, the impact of humidity alterations on structure of the peristome have never been studied. Polytrichum commune Hedw. var. commune from Guizhou Province, China, was selected as the research object to examine effects of simulated wind in the laboratory. By controlling humidity and wind, the mechanism of spore dispersal was revealed. When humidity increased, the size of the peristome and epiphragm enlarged significantly (the peristome has no obvious spatial displacement, unlike the hygroscopic movement of Arthrodontae mosses. Thus, we named it 'sub-hygroscopic movement'), then recovered to normal size when humidity decreased. When humidity was controlled and wind applied, the scattering of spores gradually decreased as the capsule dried out and finally reached a very low level; when the capsule was wetted or rewetted, the amount of spores released rose and returned to the initial state. Through comparison of moist and dry capsules, only enhanced humidity of the sporophytes led to increases in spore release. The results show that the dispersal of spores was significantly improved in windy conditions and the sub-hygroscopic movement of the capsule peristome, which ensure the continuity and effectiveness of P. commune reproduction.

Effects of humidity on natural gut harp strings

Natural gut harp strings are notoriously sensitive to changes in humidity, but the nature of this sensitivity is poorly understood. The results of some recent measurements will be presented, in which a number of well-settled strings were held at constant temperature and subjected to changes in humidity. It will be shown that there appears to be some form of coupling between humidity-induced changes in the string linear density and its tension. Moreover, these changes in linear density and tension largely cancel out, with little net effect on the string frequency. It appears, instead, that the major effect of changes in humidity is to trigger episodes of additional string creep. The longevity of gut harp strings may therefore be determined as much by their propensity to creep as by their breaking strength.

Humidity-tolerant rate-dependent capillary viscous adhesion of bee-collected pollen fluids

We report a two-phase adhesive fluid recovered from pollen, which displays remarkable rate tunability and humidity stabilization at microscopic and macroscopic scales. These natural materials provide a previously-unknown model for bioinspired humidity-stable and dynamically-tunable adhesive materials. In particular, two immiscible liquid phases are identified in bioadhesive fluid extracted from dandelion pollen taken from honey bees: a sugary adhesive aqueous phase similar to bee nectar and an oily phase consistent with plant pollenkitt. Here we show that the aqueous phase exhibits a rate-dependent capillary adhesion attributed to hydrodynamic forces above a critical separation rate. However, the performance of this adhesive phase alone is very sensitive to humidity due to water loss or uptake. Interestingly, the oily phase contributes scarcely to the wet adhesion. Rather, it spreads over the aqueous phase and functions as a barrier to water vapor that tempers the effects of humidity changes and stabilizes the capillary adhesion.

Comparison of Mechanical Properties of Natural Gut and Synthetic Polymer Harp Strings.

The long-term mechanical behaviour of a number of fluorocarbon and gut harp strings has been examined, and the results compared with a previous study of rectified nylon strings. The stretching behaviour of the three materials was studied via different measures of the Young’s modulus; with test time scales on the order of weeks, minutes, and milliseconds. The strings were subjected to cyclic variations in temperature, enabling various aspects of their thermal behaviour to be investigated. The effects of humidity changes on gut strings were also examined. The behaviour of the fluorocarbon strings was found to be similar in many ways to that of the nylon strings, despite their different chemical formulation and significantly higher density. In particular, the faster measures of Young’s modulus were found to show an almost identical strong variation with the applied stress; while the thermal behaviour of both materials was largely determined by the balance between opposing effects associated with thermal contraction and thermal variations in the Young’s modulus. The gut strings showed some similarities of behaviour to the synthetic materials, but also major differences. All three measures of the Young’s modulus remained constant as the applied stress was increased. The gut strings were far more sensitive to changes in humidity than the synthetic materials, although some of the results, especially the thermal tuning sensitivity of the strings when held at constant length, displayed remarkable stability under changing humidity. The observed behaviour suggests very strongly that there is significant coupling between humidity-related changes in the linear density of a gut string and complementary changes in its tension.

Effect of humidity changes on dimensional stability of 3D printed parts by selective laser sintering

Across many industries, additive manufacturing, also known as 3D printing, is being recognized more and more as an innovative manufacturing technology for the next generation. The automotive industry, especially, has paid huge attention to additive manufacturing, and actively applies it to their design, research, development and manufacturing processes. Selective laser sintering (SLS) in additive manufacturing is emerging and popular, and is often used to produce jigs and fixtures for cost benefits and efficiency in the manufacturing industry. However, the application of additive manufacturing is still limited due to the lack of dimensional stability of 3D printed parts associated with changes in temperature and humidity. This paper examines the effect of humidity changes on the dimensional stability of 3D printed parts made by the SLS process. The test results demonstrated changes in relative humidity may result in design specification violation in terms of dimensional requirement while in use.

Humidity sensor based on zeolite for application under environmental conditions

This work evaluates two different zeolite-based humidity sensors. In the first case, interdigital capacitive sensors (IDC-S) were fabricated on the surface of Al2O3 ceramic substrates, using electrode gaps of 20 μm, and were coated with films of LTA-type (Lind Type A) zeolite with Si/Al ratio of 1.28. Complex impedance spectroscopy (IS) was used to measure the sensor response, which was related to the change in capacitance of the interdigital electrodes and, in turn, to the electrical properties of the zeolites. The zeolite-based sensors were characterized in terms of the effects of changes in humidity and temperature on the sensor response.The results showed that this sensor provided detectable capacitance changes at very low water contents (up to 300 ppmv of H2O in N2), at temperatures ranging from 25 to 100 °C, and was therefore suitable for moisture trace measurements.In the second part of the work, evaluation was made of a humidity sensor based on ZSM-5 (Zeolite Socony Mobil - 5) zeolite. Interdigital capacitive sensors were fabricated on the surface of Al2O3 ceramic substrates, with electrode gaps of 20 μm, and were coated with films of ZSM-5. The results showed that the sensor was capable of good performance (detection limit of ∼7.32% RH) and was suitable for use under a broader range of environmental conditions (∼39% RH - 96% RH), compared to sensors based on other materials such as polyimide (detection limit of 20% RH) and TiO2 (detection limits from 10% to 30% RH).

Challenges in hydrogen quantification using Kelvin probe technique at different levels of relative humidity

Kelvin probe-based contact potential measurements were conducted with in situ electrochemical hydrogen loading of a Pd membrane with a thickness of 100 μm. The theoretical basis of diffusion coefficient calculation based on measured response time of potential drop, arising from hydrogen arriving at the detection side of the Pd membrane, was discussed. In situ hydrogen loading was also utilized for insertion of different amounts of hydrogen into the Pd sample while monitoring the resulting contact potential difference changes. Measurement of contact potential difference at different final values of hydrogen concentration in the Pd membrane was performed at various atmospheric conditions, focusing in this work on increasing relative humidity (4 to 85% rH). Moreover, the effect of humidity changes on hydrogen effusion kinetics at room temperature and low oxygen content (<1%) was studied.Graphical abstractᅟ

Analysis of changes in pulmonary functions at rest following humidity changes.

[Purpose] The purpose of this study was to compare the effect of humidity changes on the values of pulmonary function at rest. [Subjects and Methods] This study was conducted with 30 young adults (9 males, 21 females; mean age 19.4 years). Participants’ mean height was 165.1 cm, and their mean weight was 60.2 kg. The experimental setting was a laboratory in which temperature was fixed at 25 °C. Using a humidifier, relative humidity was successively to adjusted 25%, 50%, and 90%, and pulmonary were measured functions at each level. Using a spirometer, forced vital capacity (FVC), forced expiratory volume in one second (FEV1), expiratory reserve volume (ERV), and tidal volume (TV) were measured, and the results were compared and analyzed. [Results] Controlling for temperature, FVC and FEV1 showed statistically significant differences among different levels of relative humidity, but FEV1/FVC, TV, and ERV showed no significant difference. [Conclusion] In the case of exercises that require large respiration volumes, such as aerobic exercises or exercise load tests, it is recommended that higher than normal humidity levels should be maintained.

악취성 Carbonyl 화합물의 카트리지 채취 분석: 습도가 채취효율에 미치는 영향

In this study, the effect of humidity change on DNPH cartridge sampling efficiency for carbonyl compounds (CCs) has been investigated. For this analysis, gaseous standard of 6 different CCs (formaldehyde (FA), acetaldehyde (AA), propionaldehyde (PA), butyraldehyde (BA), isovaleraldehyde (IA), and valeraldehyde (VA)) was calibrated after derivatization with three types of DNPH cartridge products. Their calibration results derived at RH values between 0 and 80% were then compared against liquid phase standards. If the results of our analysis are compared by the RH values between 20 and 80%, the effect of RH can be distinguished between light and heavy CCs. For lighter CCs (like FA and AA), there was no significant change. However, for the ones heavier than PA, there was fairly noticeable increase in relative recovery ratio in RH value between 20 and 80%. Such patterns are seen consistently from all three DNPH products tested for comparison. The results of our analysis suggest that proper correction for RH change may be needed for heavier CCs by the cartridge method.

Mapping of tooth deformation caused by moisture change using moiré interferometry

Bonding of composite restorative materials to teeth usually involves surface etching and drying of both dentin and enamel. These two hard tissues have very different water contents. Objectives: The purpose of this study was to evaluate the effects of changes in humidity on the dimensional changes in dentin disks constrained by enamel and in unconstrained dentin. Methods: Changes in humidity were used to induce changes in the moisture level of the hard tissues, which created a mechanical load across the dentin–enamel junction (DEJ). High-sensitivity moiré interferometry was used to measure the magnitudes of the strains. Diffraction gratings (with a sensitivity of 2400 lines/mm) were transferred to moist polished sections of human teeth, which were subsequently dehydrated and then hydrated again. The fringe patterns from moiré interferometry recorded the change in deformation between the moisture states. Results: The results indicated that there were wide variations in strain between the two specimen geometries. The strains were fairly constant through the bulk of the dentin in both specimen types. However, the strain gradients were very high across the dentin–enamel interface into the dentin in the unconstrained geometry, and nearly zero in the constrained geometry. Significance: Moiré interferometry is a powerful tool to study the deformation of materials that are not isotropic and are not linearly elastic. It provides full-field, high-resolution deformation fields in tooth specimens. Deformations observed in this study indicate that the DEJ zone is a unique material interface that needs to be better understood in terms of normal tooth function, and that its material properties be taken into account when natural hard tissues are restored.

A unified approach to creep of wood

For many structural applications the most important mechanical property of wood is its resistance to deflection, including elastic and creep deflection. Creep includes three distinct types of behaviour, which are difficult to separate because they can all operate simultaneously. These are time–dependent (viscoelastic) creep, mechano–sorptive (moisture–change) creep, and the pseudo–creep and recovery that has been ascribed to differential swelling and shrinkage. This paper describes how two special techniques can be used to help assess the relative importance of the three types of behaviour. Contrary to previous views, the experimental results led to the conclusion that time–dependent creep and mechano–sorptive creep are different means of reaching the same creep result. This finding led, logically, to a new way of characterizing wood creep, namely, plotting data in the form of strain rate against strain. Solution of this differential equation can then lead to the more normal strain against time relation. It was also found that normalization of both the ordinate and abscissa resulted in a single master creep curve for all pieces from a given sample, and also, approximately, for all test humidities. This method therefore helps to control the important contemporary problem of using juvenile wood. By using this method, the characterization of time–dependent creep was reduced to the measurement of a master creep curve and the determination of the magnitude of the normalizing parameter. The effects of humidity changes require the additional measurement of an increased ‘activity’ associated with the molecular destabilization, and its relaxation–time constant, associated with the physical–ageing phenomenon. Application of the physical–ageing theory suggests that the speed of moisture change might be important in mechano–sorptive creep, indicating a size effect that has been predicted by van der Put but otherwise usually ignored.

Effect of Humidity on Heavy-Duty Transient Emissions from Diesel and Natural Gas Engines at High Altitude

The Code of Federal Regulations (CFR 40 Part 86 Subpart N) defines a universal humidity correction for NOx emissions from heavy–duty diesel and alternative fueled engines measured by the heavy–duty transient test. This testing procedure and humidity correction apply to any heavy–duty engine subject to regulation of particulate matter emissions, including spark ignited engines. This correction has been evaluated for a 1988 Detroit Diesel Series 60 engine and a 1995 Cummins B5.9G natural gas engine. The correction at high altitude for the diesel engine is in excellent agreement with the correction published in the Code of Federal Regulations. In addition, humidity is found to affect particulate matter in agreement with the Engine Manufacturers Association correction factor. This suggests that these results, acquired at high altitude, are generally applicable to all altitudes. CO emissions are also correlated with humidity. Emission traces show that humidity affects NOx uniformly for the diesel engine. A modification to the CFR correction method to allow accounting for the effect of humidity changes during the transient test on NOx emissions is proposed. The NOx correction factor for the natural gas engine is much more significant than for the diesel engine. Total hydrocarbon, principally methane, also correlates with humidity. The development of a natural gas correction, rather than the CFR diesel correction, for NOx and hydrocarbon emissions is suggested.

The Effect of Moisture on Layer Thicknesses Used to Monitor Global Temperatures

Abstract Mean layer virtual temperature estimates, based on geopotential height measurements, form the basis for one approach being used to monitor changes in upper-air temperature. However, virtual temperature is a function of atmospheric moisture content as well as temperature. This paper investigates the impact of real or apparent changes in atmospheric moisture on changes in mean layer virtual temperature. Real changes in mean layer specific humidity of up to 50% would cause changes in mean layer virtual temperature of less than 1°C, except in the tropical boundary layer, where the high moisture content would lead to larger virtual temperature changes. The effect of humidity changes is negligible in polar regions and most pronounced in the tropics, which could influence the interpretation of the latitudinal gradient of virtual temperature trend estimates. Improvements in radiosonde humidity sensors since 1958 have led to an apparent decrease in atmospheric humidity. On global average, for the 850–300-...

Modeling and interpreting [formula omitted] ratios in tree rings: A test case of white pine in the northeastern United States

D H ratios of cellulose nitrate in white pine ( Pinus strobus L.) from a site in southeastern New York have been used to test a model for isotopic fractionation in tree rings. Both intra-ring (six samples per year) and inter-ring samples were collected. All of the parameters currently thought to influence D H ratios in tree rings were also measured: D H ratios in source water and air vapor, temperature, and humidity. The model incorporates leaf water fractionation and fractionation during photosynthesis. In the context of the model, D H ratios in tree rings respond most strongly to changes in D H ratios of source water. This is due to negative feedback pairs which cancel the impacts of other variables. Potential effects of changes in humidity are canceled by accompanying changes in the D H ratio of air vapor. The net biological fractionation factor is apparently a function of temperature. Its change with temperature cancels the change with temperature of the phase change fractionation. The model predicts a relationship between cellulose nitrate and source water D H ratios which fits very well with the data. This predicted relationship is not applicable to all areas, however, as it depends partly on the relationship between D H ratios in air vapor and relative humidity, which can vary with location. Despite the success of the model, a less complicated model in which re-equilibration of starches with source water negates the effects of leaf water and biochemical fractionations is also compatible with the data.

Effects of humidity changes on damping and stress relaxation in wood

Mechanical damping (tan δ) and stress relaxation on pine veneer samples under stepwise humidity changes were investigated. The loss factor shows a transient peak every time the relative humidity (RH) of the surrounding atmosphere is changed. The effect appears to be associated with the diffusion of water molecules into or out of the material, the peaks being observed both when the sample is humidified (5%–85% RH) or subjected to drying. The results are supplemented by stress relaxation data obtained on similar specimens. Also in this case a higher relaxation rate is observed when the RH level around the sample is changed, the total stress decrease after several cycles being significantly larger than the corresponding value observed after the same period at the higher RH level.

THE EFFECTS OF HUMIDITY ON THE PROFILE OF PHOTOGRAPHIC PLATES

AbstractThis paper examines the quantitative measurements of out‐of‐plane displacement produced by the effect of humidity changes on photographic plates in an attempt to provide a compensation which can be applied in situations involving photographic measurements in unstable ambient conditions. The two approaches discussed are profile measurements by holographic methods and a mechanical transducer technique.

A personal sampling method for the determination of nitrous oxide exposure.

A diffusive sampler is described which is suitable for the determination of time weighted average personal and static exposures to nitrous oxide. The sampler is based on a commercially available tube design and is analyzed by thermal desorption techniques. The performance of the sampler when exposed to a wide range of nitrous oxide concentrations is described. The effects of humidity changes on diffusive uptake have been tested and shown to be negligible. The precision of the sampler has been determined and the effects of back-diffusion and storage have been investigated. The results of these experiments and those of field comparisons between the diffusive sampler and conventional pump and tube techniques suggest that the precisions of both methods are similar. The diffusive method is preferred because of its simplicity and convenience.

EFFECT OF AMBIENT HUMIDITY AND LEAF DISPOSITION ON LEAF DIFFUSIVE CONDUCTANCE OF FESTUCA ARUNDINACEA CV. S170

SummaryThe effects of changes in humidity on leaf diffusive conductance of Festuca arundinacea cv. SI 70 during a sequence of changes in leaf orientation were studied in a controlled environment cabinet. Reducing the vapour pressure deficit from 0.95 to 0.32 kPa at 25 °C (increasing relative humidity from 70 to 90 %) increased total leaf conductance by 73 %. Leaf orientation markedly influenced the conductance of individual leaf surfaces, the uppermost nearly always having the greater conductance.Total leaf conductance was greater when the ridged adaxial surface was uppermost and, overall, the adaxial surface was more sensitive than the abaxial to humidity and orientation changes. Mean leaf conductance was significantly greater 8 h after the lights were switched on than after 1 and 4 h. Leaves which naturally displayed the adaxial surface upwards had a higher leaf conductance than those in which the abaxial surface was normally uppermost for most of their length.