Global change drivers (elevated atmospheric CO.sub.2, rising surface temperatures, and changes in resource availability) have significant consequences for global plant communities. In the northern ...sagebrush steppe of North America, the invasive annual grass Bromus tectorum (cheatgrass) is expected to benefit from projected warmer and drier conditions, as well as increased CO.sub.2 and nutrient availability. In growth chambers, we addressed this expectation using two replacement series experiments designed to test competition between B. tectorum and the native perennial bunchgrass Pseudoroegneria spicata. In the first experiment, we tested the effects of elevated temperature, decreased water and increased nutrient availability, on competition between the two species. In the second, we tested the effects of elevated atmospheric CO.sub.2 and decreased water availability on the competitive dynamic. In both experiments, under all conditions, P. spicata suppressed B. tectorum, though, in experiment one, warmer and drier conditions and elevated nutrient availability increased B. tectorum's competitiveness. In experiment two, when grown in monoculture, both species responded positively to elevated CO.sub.2. However, when grown in competition, elevated CO.sub.2 increased P. spicata's suppressive effect, and the combination of dry soil conditions and elevated CO.sub.2 enhanced this effect. Our findings demonstrate that B. tectorum competitiveness with P. spicata responds differently to global change drivers; thus, future conditions are unlikely to facilitate B. tectorum invasion into established P. spicata communities of the northern sagebrush steppe. However, disturbance (e.g., fire) to these communities, and the associated increase in soil nutrients, elevates the risk of B. tectorum invasion.
Abstract In the paper, effects of temperature and launch pressure on variations of the maximum impact acceleration in cross media water-entry process are systematically investigated via experiments. ...Results indicated that under the water entry angle of 25°, the maximum impact acceleration increased gradually with the growing of launch pressure from 2.5MPa to 3.0MPa when the temperature is 30°C, 40°C, and 50°C. The maximum impact acceleration decreased constantly with the increase of the temperature from 30°C to 50°C when launch pressure is the constant. According to the comprehensive analysis, effect degrees of variations of the launch pressure on the maximum impact acceleration are more significant than that of the variations of temperature.
Few studies have examined variation in the associations between heat waves and mortality in an international context.
We aimed to systematically examine the impacts of heat waves on mortality with ...lag effects internationally.
We collected daily data of temperature and mortality from 400 communities in 18 countries/regions and defined 12 types of heat waves by combining community-specific daily mean temperature ≥90th, 92.5th, 95th, and 97.5th percentiles of temperature with duration ≥2, 3, and 4 d. We used time-series analyses to estimate the community-specific heat wave-mortality relation over lags of 0-10 d. Then, we applied meta-analysis to pool heat wave effects at the country level for cumulative and lag effects for each type of heat wave definition.
Heat waves of all definitions had significant cumulative associations with mortality in all countries, but varied by community. The higher the temperature threshold used to define heat waves, the higher heat wave associations on mortality. However, heat wave duration did not modify the impacts. The association between heat waves and mortality appeared acutely and lasted for 3 and 4 d. Heat waves had higher associations with mortality in moderate cold and moderate hot areas than cold and hot areas. There were no added effects of heat waves on mortality in all countries/regions, except for Brazil, Moldova, and Taiwan. Heat waves defined by daily mean and maximum temperatures produced similar heat wave-mortality associations, but not daily minimum temperature.
Results indicate that high temperatures create a substantial health burden, and effects of high temperatures over consecutive days are similar to what would be experienced if high temperature days occurred independently. People living in moderate cold and moderate hot areas are more sensitive to heat waves than those living in cold and hot areas. Daily mean and maximum temperatures had similar ability to define heat waves rather than minimum temperature. https://doi.org/10.1289/EHP1026.
•The effects of temperature on the performance of batteries were performed.•Battery modeling methods and thermal management strategies were discussed.•A systematic review of liquid based thermal ...management system was presented.•An integrated system with suitable energy allocation and control unit is desirable.
Electric vehicles with green power system are viable alternatives to reduce greenhouse gas emissions and dependence on fossil energy resources. The power source such as Li-ion battery has high sensitivity to temperature, which is a challenge related to battery thermal management. Battery thermal management system plays a vital role in the high efficiency, dependability and security of these batteries. Modern commercial electric vehicles normally use liquid based battery thermal management system, which has high heat transfer efficiency with the function of cooling or heating. This paper firstly looks at the effects of temperature on the battery performance from three aspects: low temperature, high temperature and differential temperature. Then the battery management system is discussed with the main emphasis on battery modeling methods and thermal management strategies. Further, a systematic review of liquid based system is presented in terms of direct and indirect contact mode. Progress made in liquid channel configuration and heat transfer fluid aiming at improving the overall thermal performance is also discussed. With the function of liquid-gas phase change process, the heat pipe based battery thermal management is feasible and effective for its high heat transfer efficiency. To further facilitate vehicle-mounted energy optimization, an integrated vehicle thermal management system with appropriate energy allocation is required. In addition, the battery thermal management system connected with the other subsystems (e.g., heating ventilation air conditioning system) by utilizing the liquid circulation in vehicle thermal management has great potential in energy-saving and efficiency promotion.
The phenomenon of contact electrification (CE) has been known for thousands of years, but the nature of the charge carriers and their transfer mechanisms are still under debate. Here, the CE and ...triboelectric charging process are studied for a metal–dielectric case at different thermal conditions by using atomic force microscopy and Kelvin probe force microscopy. The charge transfer process at the nanoscale is found to follow the modified thermionic‐emission model. In particular, the focus here is on the effect of a temperature difference between two contacting materials on the CE. It is revealed that hotter solids tend to receive positive triboelectric charges, while cooler solids tend to be negatively charged, which suggests that the temperature‐difference‐induced charge transfer can be attributed to the thermionic‐emission effect, in which the electrons are thermally excited and transfer from a hotter surface to a cooler one. Further, a thermionic‐emission band‐structure model is proposed to describe the electron transfer between two solids at different temperatures. The findings also suggest that CE can occur between two identical materials owing to the existence of a local temperature difference arising from the nanoscale rubbing of surfaces with different curvatures/roughness.
The effect of temperature on contact electrification (CE) is investigated at the nanoscale. It is found that hotter materials tend to be positively charged while cooler materials tend to be negatively charged in CE. Based on the results, an electron thermal‐emission model is proposed. The temperature effect provides strong evidence for electron transfer in CE.
Extracted Mango and Orange juices were investigated by using spectroscopic techniques such as UV/Visible and Fluorescence. Three portions of samples (fresh juice) were stored at 22 °C for eight days, ...stored in a water bath and heated at 40 °C, 60 °C, and 80 °C for ten minutes. The highest wavelengths (455 nm) were observed from the UV/Vis results for fresh Mango juices, while 270 nm and 460 nm were observed for stored Mango juices. Furthermore, wavelengths of 320 nm were observed in heat-treated mango juice (40 °C). No absorption peaks were observed at 60 °C and 80 °C due to temperature effects. Absorption peaks of fresh fruit were observed at 330 nm and 390 nm, while 260 nm and 320 nm reflect stored orange juices absorptions peaks. From heat-treated stored (40 °C and 60 °C) samples, 320 nm and 260 nm absorption peaks were observed, respectively. Wavelength observed (454 nm, 540 nm & 700 nm) peaks represent the fresh mango juice spectra, while 460 nm and 700 nm are for stored Mango juices. The peaks observed in the region of 400-500 nm and at 700 nm represent heat-treated mango juices at 40 °C. Heat stored Mango juices (60 °C & 80 °C) have peaks at 700 nm. Peaks observed at 700 nm, 500 nm, and 455 nm reflect fresh orange juice, while 460-500 nm and 700 nm represent the emission spectra of the samples. The stored orange juice peaks at 460-500 nm and at 700 nm, but heated-stored orange juice peaks only at 700 nm. The pH values for orange and mango juices were 3.52-3.73 and 4.02-4.72, respectively.
Abstract The study presents results concerning the comparison of modelling and experimental work on rubberized concrete exposed to high temperatures. Crumb rubber was used in different concentrations ...to replace coarse aggregate. Experiments were made on flat-cylindrical specimens extracted from larger samples in order to be analysed. Simulations have been employed to calibrate measurements and to further analyse the specimens in an effort to prove their worth as a viable mechanism in studying larger-scale phenomena.
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