Effect Of Environmental Temperature Research Articles

Mode transition of air surface micro-discharge and its effect on the water activation and antibacterial activity

The chemical characteristics of atmospheric pressure dielectric barrier discharge plasma generated in air are very sensitive to some factors, such as environment temperature and discharge power. There are two typical modes, namely the ozone mode and nitrogen oxides mode. In this paper, the air surface micro-discharge plasma in the ozone mode and nitrogen oxides mode are respectively generated at environment temperatures of 5 °C and 50 °C when discharge power is almost kept at 6 W, and the plasma-activated water (PAW) is prepared by means of passing the plasma exhaust gases into deionized water. By comparing the reactive species in PAW under these two modes and their sterilization effects, it is found that the concentrations of H+, H2O2, NO2 −, NO3 − and ONOO− in PAW for the nitrogen oxides mode are about 2–3 fold over those for the ozone mode, while the concentration of O3 in PAW for the ozone mode is more than 28 times that in the nitrogen oxides mode. The sterilization effect under the nitrogen oxides mode is two orders of magnitude higher than that in the ozone mode. For the biological effects, it is found that treatment of a methicillin-resistant Staphylococcus aureus suspension by PAW leads to approximately a four-log reduction in the nitrogen oxides mode, which is higher than that in the ozone mode, leading to speculations that the reactive nitrogen species represented by ONOO− in PAW may be the critical species in sterilization. Furthermore, the transition between ozone mode and nitrogen oxides mode can be achieved by adjusting the discharge power. Interestingly, both of the compositions and concentrations of the reactive species in gas and liquid phases under 5 °C & 9.5 W and 50 °C & 6 W conditions are roughly identical, indicating that the effect of environment temperature on the mode transition is consistent with that of discharge power.

Vibration frequency of thick functionally graded material cylindrical shells with fully homogeneous equation and third-order shear deformation theory under thermal environment

The effects of third-order shear deformation theory and varied shear correction coefficient on the vibration frequency of thick functionally graded material cylindrical shells with fully homogeneous equation under thermal environment are investigated. The nonlinear coefficient term of displacement field of third-order shear deformation theory is included to derive the fully homogeneous equation under free vibration of functionally graded material cylindrical shells. The determinant of the coefficient matrix in dynamic equilibrium differential equations under free vibration can be represented into the fully fifth-order polynomial equation, thus the natural frequency can be found. Two parametric effects of environment temperature and functionally graded material power law index on the natural frequency of functionally graded material thick cylindrical shells with and without the nonlinear coefficient term of displacement fields are computed and investigated.

Effects of environmental temperature and sample pre-straining on high cycle fatigue strength of WE43-T5 magnesium alloy

This work investigates the effects of test temperature and sample pre-straining on the high cycle fatigue behavior of a magnesium alloy, WE43. Fatigue strength is found to deteriorate with environmental temperature from room to 100℃. In contrast to the samples pre-strained in tension, fatigue strength improves for the samples pre-strained in compression. The peak improvements of over 2x is determined for the samples pre-compressed to 6% strain. Significantly, the alloy sufficiently pre-strained in compression begins to exhibit the endurance limit. The interesting characteristics of the alloy behavior in fatigue are rationalized in terms of the microstructural evolution and deformation mechanisms.

LAJU PENDINGINAN PENGELASAN BAJA CARBON SEDANG PADA TEMPERATUR LINGKUNGAN BERBEDA

The quality of welding results is influenced by the shape of the microstructure of the welding material especially in the HAZ region. The shape of the welding microstructure is largely determined by the cooling rate of the weld material. The cooling rate of the weld is greatly influenced by the heat input from the arc and the ambient temperature. This study aimed to determine the effect of different environmental temperatures on the cooling rate of welding results. Welding of GMAW fillets on medium carbon steel plates S50C, with variations in welding currents 90 A, 100A and 110A and carried out at variations in environmental temperature of 15oC, 10oC and 5oC. Temperature data on the middle, welding part is taken with a digital thermometer to compare the effect of each variable. The test results show that the greater the welding current, the slower the cooling rate. Similarly, an increase in ambient temperature causes a decrease in the weld metal's cooling rate.

The Friction and Wear Behaviors of Vegetable Oil‐Based Waxes, Natural Beeswax, and Petroleum Paraffin Wax

AbstractQuantitative analyses on the coefficient of friction of common coating waxes are necessary and essential for designing systems for coating, conveying, packaging operations, transporting, and storing of papers and paperboards, while analyses on wear behavior can be helpful for predicting performance durability of the coating surface. In this study, we investigated the friction and wear behaviors of six waxes including four commercial waxes and two soybean oil‐based wax developed in our lab for bulk corrugated coating. The effect of normal load, sliding velocity, and environmental temperature was evaluated. The friction coefficient of different waxes varies with sliding conditions. Higher normal load, sliding velocity, and environmental temperature resulted in significantly greater wear loss. Crystalline morphology and crystallinity of waxes were affected by the environmental temperature, and they correlate to the variations in friction coefficient and wear loss of these materials.

Modelling the effect of environmental temperatures, microhabitat and behavioural thermoregulation on predicted activity patterns in a desert lizard across its thermally diverse distribution

AbstractAimTemperature plays an important role in determining distributions of ectothermic species, yet many ectotherms have wide distributions across diverse environmental conditions. Our goal was to model regional differences in annual and seasonal activity patterns among populations of Phrynosoma platyrhinos across its climatically diverse distribution. We hypothesize that microhabitat availability and behavioural thermoregulation will not mitigate large‐scale climatic differences across the species' distribution, resulting in alteration of activity patterns of populations.LocationWestern deserts of North America.TaxonDesert Horned Lizard (Phrynosoma platyrhinos).MethodsWe used biophysical models to (a) model microhabitat conditions at 31 localities across the species' range, (b) model body temperature profiles of a theoretical lizard using microhabitat conditions, physiological and thermal parameters and the ability of lizards to thermoregulate behaviourally and (c) predict year‐round activity patterns of P. platyrhinos across its range, quantified as the percentage of time permissible for basking or foraging.ResultsThe models identified that different populations of P. platyrhinos experience differences in predicted activity patterns, both daily and seasonally, with up to 67% more time suitable for foraging in the southern than northern deserts. Southern populations have more potential for year‐round activity, but predicted activity is reduced during hot summer months. The northern populations have less time for activity overall because of low temperatures in the spring and fall. However, summer‐predicted activity is greater than in the southern regions.Main conclusionsWe detected pronounced regional differences in the times available to P. platyrhinos for activity. We conclude that behaviour and microclimate conditions are not able to fully mitigate the effects of large‐scale thermal variation, and that lizards compensate for climatic variation by shifting their daily and seasonal predicted activity patterns. These differences can be tied to inter‐population variation in life history traits.

Laboratory Study on the Performance of Asphalt Mixes Modified with a Novel Composite of Diatomite Powder and Lignin Fiber

The performance and the fundamental weaknesses of asphalt mix under environmental temperature and water effects have made researchers try to modify the asphalt mix properties by using the proper additives. For this reason, this paper aims to improve the anti-cracking performance and water stability of asphalt pavement by adding a novel composite of diatomite and lignin fiber in asphalt mixes. Four types of asphalt mixes, including control asphalt mix (CAM), diatomite modified asphalt mix (DMAM), lignin fiber modified asphalt mix (LFMAM), and diatomite-lignin fiber composite modified asphalt mix (DLFMAM) were prepared in the laboratory. Low-temperature bending test, Marshall Immersion test, and freeze-thaw splitting test were employed to evaluate the performance of the asphalt mixes. Results reveal that the use of the lignin fiber in reinforced asphalt mixes combined with diatomite led to an enhancement in the asphalt pavement performance more than the other three types of mixes. Diatomite has an important influence on the water damage resistance of asphalt mix more than lignin fiber. On the other hand, diatomite has a small effect on the anti-cracking performance; meanwhile, lignin fiber showed a significant improvement in the cracking resistance of asphalt mixes. DLFMAM has the best traveling performances among all asphalt mixes. Thus, this work provides a good reference for the design of composite asphalt mixes.

Theoretical efficiency limit of graphene-semiconductor solar cells

The maximum power conversion efficiency (PCE) of graphene-semiconductor solar cells (GSSCs) is calculated with regard to the universal scaling laws of thermionic emission across graphene/3D-semiconductor Schottky junctions. The performance of GSSCs as a function of the interface Schottky barrier height and the bandgap of semiconductor (Eg) is investigated. Under ideal conditions, these photovoltaic cells reveal a broad maximum at Eg=1.1–1.7 eV with PCE exceeding 25%. The efficiency limits of graphene/silicon and graphene/GaAs solar cells are determined to be 25.5% and 27.5%, respectively. The effect of environmental temperature on the solar cell performance is also investigated, and it is found that to a good degree, the PCE of GSSCs varies linearly with temperature. The thermal coefficients of PCE for graphene/silicon and graphene/GaAs solar cells are obtained to be −0.076%/K and −0.058%/K, respectively. This study is of fundamental importance for GSSCs and provides insights for further improvements.

An investigation of the improvement in energy storage performance of Na2/3Mn1/2Fe1/2O2 by systematic Al-substitution

We successfully fabricated Na2/3Mn1/2Fe1/2−xAlxO2, where x = 0, 0.01, … 0.10, by a modified solid-state reaction technique. The structural properties of the Al-substituted samples were investigated by x-ray diffraction (XRD), scanning electron microscope (SEM), Fourier transform infrared spectroscopy and x-ray absorption fine structure (XAFS) measurements. It was found that there were no impurity phases in the XRD patterns of the samples and they fit the P63/mmc symmetry. The Al substitution in Na2/3Mn1/2Fe1/2O2 causes a decrease in the a-lattice parameter, but the c-parameter starts to increase after a certain substitution value of Al. We suggest that a certain proportion of Al in the samples triggers the change of the spin configuration of the Fe ions, and it may cause an increase in the lattice parameters. The size of the grains was found to be less than 0.9 µm, from SEM images for all samples. The valence states of the substituted samples as well as the local structure around Fe and Mn were investigated by means of XAFS measurements. The highest capacity for the first cycle was obtained as 134.3 mAh/g for x = 0.07, and the best capacity fade was found to be 0.23 for x = 0.08 substitution. So, the highest performance of the Al-substituted cells was found when 0.08 ≥ x ≥ 0.06. The environmental temperature effects on the battery cells were determined at 10 oC, room temperature and 50 oC, and it was found that the temperature plays a crucial role in the Na-ion batteries.

Environmental relative humidity affects Schirmer tear test results in normal dogs.

To investigate the effects of environmental temperature and relative humidity on tear test results in dogs. 22 normal dogs. Routine Schirmer tear tests (STT1) and phenol red thread tests (PRTT) were administered to normal dogs in four environmental conditions with different relative humidity (RH) and temperature (T). Environmental conditions (mean±SD) included the following: normal indoor (RH=49±4%, T=72±2°F), outdoor (RH=62±11%, T=85±6°F), indoor high humidity (RH=85±6%, T=71±1°F), and indoor low humidity (RH=39±2%, T=76±1°F). ANCOVA models were used to assess for significant associations between tear test readings and RH/T (P<.05). A significant, direct positive relationship between RH and STT1 results was detected (y=0.04909*X+19.11, P=.006) but not between T and STT1. There was no significant relationship between PRTT and RH or T. These results suggest that STT1 but not PRTT is affected by RH and that T does not influence STT1 or PRTT results in normal dogs. RH is unlikely, however, to cause clinically significant effects on STT1 readings in normal dogs when performed in average indoor conditions. Future studies should investigate the influence of RH on STT1 readings obtained in dogs with keratoconjunctivitis sicca.

Temperature-dependent proportional limit stress of SiC/SiC fiber-reinforced ceramic-matrix composites

AbstractIn this paper, the temperature-dependent proportional limit stress (PLS) of SiC/SiC fiber-reinforced ceramic-matrix composites (CMCs) is investigated using the micromechanical approach. The PLS of SiC/SiC is predicted using an energy balance approach considering the effect of environment temperature. The relation between the environment temperature, PLS, and composite damage state is established. The effects of the fiber volume, interface properties, and matrix properties on the temperature-dependent PLS and composite damage state of SiC/SiC composite are analyzed. The experimental PLS and interface debonding length of 2D SiC/SiC composites with the PyC and BN interphase at elevated temperatures are predicted. The temperature-dependent PLS of SiC/SiC composite increases with the fiber volume, interface shear stress and interface debonding energy, and the matrix fracture energy and decreases with the interface frictional coefficient at the same temperature.

Multivariate Analysis of Black Race and Environmental Temperature on COVID-19 in the US

BackgroundThere has been much interest in environmental temperature and race as modulators of Coronavirus disease-19 (COVID-19) infection and mortality. However, in the United States race and temperature correlate with various other social determinants of health, comorbidities, and environmental influences that could be responsible for noted effects. This study investigates the independent effects of race and environmental temperature on COVID-19 incidence and mortality in United States counties. MethodsData on COVID-19 and risk factors in all United States counties was collected. 661 counties with at least 50 COVID-19 cases and 217 with at least 10 deaths were included in analyses. Upper and lower quartiles for cases/100,000 people and halves for deaths/100,000 people were compared with t-tests. Adjusted linear and logistic regression analyses were performed to evaluate the independent effects of race and environmental temperature. ResultsMultivariate regression analyses demonstrated Black race is a risk factor for increased COVID-19 cases (OR=1.22, 95% CI: 1.09–1.40, P=0.001) and deaths independent of comorbidities, poverty, access to health care, and other risk factors. Higher environmental temperature independently reduced caseload (OR=0.81, 95% CI: 0.71–0.91, P=0.0009), but not deaths. ConclusionsHigher environmental temperatures correlated with reduced COVID-19 cases, but this benefit does not yet appear in mortality models. Black race was an independent risk factor for increased COVID-19 cases and deaths. Thus, many proposed mechanisms through which Black race might increase risk for COVID-19, such as socioeconomic and healthcare-related predispositions, are inadequate in explaining the full magnitude of this health disparity.

Behavioral constraints on local adaptation and counter-gradient variation: Implications for climate change.

Resource allocation to growth, reproduction, and body maintenance varies within species along latitudinal gradients. Two hypotheses explaining this variation are local adaptation and counter‐gradient variation. The local adaptation hypothesis proposes that populations are adapted to local environmental conditions and are therefore less adapted to environmental conditions at other locations. The counter‐gradient variation hypothesis proposes that one population out performs others across an environmental gradient because its source location has greater selective pressure than other locations. Our study had two goals. First, we tested the local adaptation and counter‐gradient variation hypotheses by measuring effects of environmental temperature on phenotypic expression of reproductive traits in the burying beetle, Nicrophorus orbicollis Say, from three populations along a latitudinal gradient in a common garden experimental design. Second, we compared patterns of variation to evaluate whether traits covary or whether local adaptation of traits precludes adaptive responses by others. Across a latitudinal range, N. orbicollis exhibits variation in initiating reproduction and brood sizes. Consistent with local adaptation: (a) beetles were less likely to initiate breeding at extreme temperatures, especially when that temperature represents their source range; (b) once beetles initiate reproduction, source populations produce relatively larger broods at temperatures consistent with their local environment. Consistent with counter‐gradient variation, lower latitude populations were more successful at producing offspring at lower temperatures. We found no evidence for adaptive variation in other adult or offspring performance traits. This suite of traits does not appear to coevolve along the latitudinal gradient. Rather, response to selection to breed within a narrow temperature range may preclude selection on other traits. Our study highlights that N. orbicollis uses temperature as an environmental cue to determine whether to initiate reproduction, providing insight into how behavior is modified to avoid costly reproductive attempts. Furthermore, our results suggest a temperature constraint that shapes reproductive behavior.

Effect of temperature on matrix multicracking evolution of C/SiC fiber-reinforced ceramic-matrix composites

AbstractIn this paper, the temperature-dependent matrix multicracking evolution of carbon-fiber-reinforced silicon carbide ceramic-matrix composites (C/SiC CMCs) is investigated. The temperature-dependent composite microstress field is obtained by combining the shear-lag model and temperature-dependent material properties and damage models. The critical matrix strain energy criterion assumes that the strain energy in the matrix has a critical value. With increasing applied stress, when the matrix strain energy is higher than the critical value, more matrix cracks and interface debonding occur to dissipate the additional energy. Based on the composite damage state, the temperature-dependent matrix strain energy and its critical value are obtained. The relationships among applied stress, matrix cracking state, interface damage state, and environmental temperature are established. The effects of interfacial properties, material properties, and environmental temperature on temperature-dependent matrix multiple fracture evolution of C/SiC composites are analyzed. The experimental evolution of matrix multiple fracture and fraction of the interface debonding of C/SiC composites at elevated temperatures are predicted. When the interface shear stress increases, the debonding resistance at the interface increases, leading to the decrease of the debonding fraction at the interface, and the stress transfer capacity between the fiber and the matrix increases, leading to the higher first matrix cracking stress, saturation matrix cracking stress, and saturation matrix cracking density.

Effect of environmental temperature and humidity on milk production and milk composition of Guanzhong dairy goats

The present study was undertaken with the aim to examine the relationship between temperature and humidity and milk production traits in Guanzhong dairy goats reared in China, and to assess the possibility of future genetic selection in dairy goats for increased tolerance to adverse environmental conditions, thereby improving goat farm management in China. Production data included 149 Guanzhong dairy goats with the first-lactation collected throughout 2019. The traits investigated were milk yield, and indicators of milk composition of Guanzhong dairy goats. For high temperature, significant and marked daily milk yield drops, up to 16% (about 0.23 kg/d per head) were observed in July and August when compared with the other months. The fat content, protein content, and dry matter were significantly lower in July and August. Importantly, milk production traits present significant correlations with high temperature, while high humidity had little effect on milk composition of Guanzhong dairy goats. Therefore, the adverse environmental conditions on farm profit is not negligible, and the strategies could be improving the goat farm management as well as obtaining thermotolerant animals through genetic selection.

A cointegration approach for cable anomaly warning based on structural health monitoring data: An application to cable-stayed bridges

For long-span cable-stayed bridges, cables are one of the most important components to resist various actions. With the application of structural health monitoring technique, real-time recording of cable forces is achieved, and hence, the warning system on cable anomaly established. However, it is still difficult and there are challenges to conduct the warning system effectively, especially due to the phenomena of false alarm or omission. A practical reason is the warning index’s sensitivity to the ambient environment. Temperature variations, for instance, usually disturb the force-based cable anomaly warning and result in the false evaluation of structural condition. In view of eliminating the effects of environmental temperature, cointegration, a statistical concept from econometrics, is employed in cable anomaly warning studies. An approach that extracts warning index by linear combination of two non-stationary time series using the cointegration algorithm is developed in order to produce a more stationary cointegrated residual series (warning index series). The calculated stationary relationship between two time series is insensitive to the influence of environmental temperature and is capable of cable anomaly warning. Specifically, the framework of the cable anomaly warning system is first proposed. Subsequently, time-series test methods are introduced to check the non-stationary order and calculate the cointegration parameters of measured cable forces and environmental temperature. The computed cointegrated residual series is fed into statistical analysis as a warning index and the procedure of cable anomaly warning under the influence of environmental temperature is illustrated in detail. Finally, a case study for a cable-stayed bridge is demonstrated with results and discussions.

Life Cycle Dynamics of a Key Marine Species Under Multiple Stressors

Identifying key indicator species, their life cycle dynamics and the multiple driving forces they are affected by is an important step in ecosystem-based management. Similarly important is understanding how environmental changes and trophic interactions shape future trajectories of key species with potential implications for ecosystem state and service provision. We here present a statistical modelling framework to assess and quantify cumulative effects on the long-term dynamics of the copepod Pseudocalanus acuspes, a key species in the Baltic Sea. Our model integrates linear and non-linear responses to changes in life stage density, climate and predation pressure as well as stochastic processes. We use the integrated life cycle model to simulate copepod dynamics under a combination of stressor scenarios and to identify conditions under which population responses are potentially mitigated or magnified. Our novel modelling approach reliably captures the historical P. acuspes population dynamics and allows us to identify females in spring and younger copepodites in summer as stages most sensitive to direct and indirect effects of the main environmental stressors, salinity and temperature. Our model simulations furthermore demonstrate that population responses to stressors are dampened through density effects. Multiple stressor interactions were mostly additive except when acting on the same life stage. Here, negative synergistic and positive dampening effects lead to a lower total population size than expected under additive interactions. As a consequence, we found that a favorable increase of oxygen and phosphate conditions together with a reduction in predation pressure by 50% each could counteract the negative effect of a 25% decrease in salinity by only 6%. We therefore advocate that management strategies aimed to mitigate the effects of climate-related stressors should target life stage not affected by climate for more effective and predictable results. Our modelling framework can help here as simple tool for species with a discrete life cycle to explore stressor interactions and the safe operating space under future climate change.

Thermodynamic performance assessment of boron based thermochemical water splitting cycle for renewable hydrogen production

The present study is related with the thermodynamic performance assessment of renewable hydrogen production through Boron thermochemical water splitting cycle. Therefore, all step efficiencies and overall cycle efficiency are calculated based on complete reaction. Additionally, a parametric study is conducted to determine the effect of the reference environment temperature on the overall cycle efficiency. In this regard, exergy efficiencies, exergy destruction rates and also inlet and outlet exergy rates of the cycle are calculated and presented for various reference temperatures. The exergy efficiency of the cycle is calculated as 0.4393 based on complete reaction and occurs at 298 K. This study has shown that Boron thermochemical water splitting cycle has a great potential due to cycle performance. As a result, Boron based thermochemical water splitting cycle can help achieve better environment and sustainability due to high exergetic efficiency. By the way, economic and technical issues of the storage and transportation of the hydrogen can find a proper solution if the hydrogen production reaction of the Boron thermochemical water splitting cycle takes place on-board of a vehicle.

Effect of Environmental Temperature and Humidity on Different Metal Oxide Gas Sensors at Various Gas Concentration Levels

Metal Oxide (MOX) semiconductor gas sensors have been widely used in monitoring targeted gases that are present in the environment. This type of gas sensor can also be utilized as a safety device to detect the source of gas leakage. Their uses in many applications are due to being user-friendly, lower in cost, high sensitivity and relatively quick response time. However, there are several factors that could affect their performance. This work investigates the effects of the changes in ambient temperature and humidity on the readings of these sensors at various gas concentration levels. A PCB board was developed, which consists of temperature and humidity sensors, as well as eight different MOX gas sensors (TGS2600, TCS2602, CCS803, MiCS552, GM-402B, GM-502B, GM-702B and MiCS6814). The board was subjected to various temperatures (16˚C to 30˚C) and humidity levels (45% to 75%). At each of these parameter settings, the gas sensor responses were recorded at different ethanol gas concentrations. The results of the study showed that the temperature and humidity affected all the gas sensor response. The magnitude of the sensors responses was observed to decrease with rising temperature and humidity levels, except for MICS6814 (NH3 sensor) which responses in the opposite manner. Hence, there is the need to take into consideration of the drift of gas sensors’ responses when there are changes in temperature and humidity.

An Analytical Approach of Nonlinear Thermo-mechanical Buckling of Functionally Graded Graphene-reinforced Composite Laminated Cylindrical Shells under Compressive Axial Load Surrounded by Elastic Foundation

This paper deals with an analytical approach to predict the nonlinear buckling behavior of functionally graded graphene-reinforced composite laminated cylindrical shells under axial compressive load surrounded by Pasternak’s elastic foundation in a thermal environment. Piece-wise functionally graded graphene-reinforced, composite layers are sorted with different types of graphene distribution. The governing equations are established by using Donnell’s shell theory with von Karman nonlinearity terms and three-term solution of deflection is chosen for modeling the uniform deflection of pre-buckling state, linear and nonlinear deflection of post-buckling state. Galerkin method is applied to determine the critical axial compressive buckling load expression, post-buckling load-deflection and load-end shortening relations of the shell. The effects of environment temperature, foundation, geometrical properties, and graphene distribution on buckling behavior of shell, are numerically evaluated.