Negative Effect Of Temperature Research Articles

Demographic and net primary productivity dynamics of primary and secondary tropical forests in Southwest China under a changing climate

AbstractTropical forests are major carbon sinks on the Earth's land surface. However, our understanding of how the demographic rate and carbon sink capacities of tropical forests respond to climate change remains limited. In this study, we investigated the impacts of environmental drivers on forest growth, mortality, recruitment, and stem net primary productivity (NPPstem) over 16 years at five tropical forest plots in Xishuangbanna, Southwest China. These plots are along a successional gradient spanning three tropical secondary forests (tropical secondary forest‐1 [TSF‐1], tropical secondary forest‐2 [TSF‐2], and tropical secondary forest‐3 [TSF‐3]) and two primary forests (tropical rainforest [TRF] and tropical karst forest [TKF]). Our results showed that early successional secondary forests (TSF‐2 and TSF‐3) had higher diameter growth rates and relative mortality rates. An extreme drought event during 2009–2010 reduced the growth rate, relative recruitment rate, and NPPstem for most plots while increasing mortality in early successional forest plots. We observed significant negative effects of maximum temperature (Tmax) on NPPstem and diameter growth rate across all plots. Additionally, we found that precipitation had significant positive effects on diameter growth rate across all plots. Furthermore, tree mortality increased with rising Tmax, whereas precipitation significantly enhanced tree recruitment. Our findings highlight the vulnerability of tree growth, mortality, recruitment, and productivity in tropical forests to extreme drought events in Southwest China. Continued climate warming and more frequent droughts will induce higher mortality rates and impede growth, thus reducing the carbon sink capacity of tropical forests, especially in early successional stage tropical secondary forests.

Temperatures and Their Impact on Tourism Activity in Dhi Qar Governorate: An Applied Climate Study

Temperatures significantly impact individuals, affecting their health and comfort. Extreme temperatures, whether high or low, can hinder a person's ability to work and engage in various activities. Consequently, people seek to minimize the negative effects of temperature on their comfort by finding places that alleviate thermal discomfort. Tourism is particularly sensitive to temperature variations, thriving during times and seasons with moderate temperatures and a comfortable atmosphere. Tourist activity tends to increase during these favorable periods, while it declines markedly during seasons with extreme temperatures. This research investigates the impact of three climatic elements on tourism activity in Dhi Qar Governorate. The study adopts Thom's temperature hypothesis and the wind cooling hypothesis by Sabul and Basel to determine the types of comfort influencing tourism in the area, utilizing climatic data from the Nasiriyah station. The analysis identifies general comfort levels, both day and night, to ascertain the optimal times and months for tourism. The findings reveal that March and November are the most comfortable and ideal months for tourism based on general temperature and humidity. April and November are considered relatively comfortable, with 10% of tourists experiencing some discomfort. When examining temperature and humidity during the day, December and February are identified as the best months for tourism, providing complete comfort. March, November, and January are found to be relatively comfortable. Additionally, the study evaluates the effect of wind on tourist comfort using general temperature and wind speed data. The wind cooling hypothesis shows that winds significantly cool the atmosphere in April and October (primary degree) and in February and November (secondary degree), making these months colder. In contrast, the negative impact of winds becomes evident during the extremely hot summer months, making the weather unsuitable for tourism.

The role of cis-zeatin in enhancing high-temperature resistance and fucoxanthin biosynthesis in Phaeodactylum tricornutum.

Phaeodactylum tricornutum a prominent source of industrial fucoxanthin production, faces challenges in its application due to its tolerance to high-temperature environments. This study investigates the physiological responses of P. tricornutum to high-temperature stress and its impact on fucoxanthin content, with a specific focus on the role of cis-zeatin. The results reveal that high-temperature stress inhibits P. tricornutum's growth and photosynthetic activity, leading to a decrease in fucoxanthin content. Transcriptome analysis shows that high temperature suppresses the expression of genes related to photosynthesis (e.g., psbO, psbQ, and OEC) and fucoxanthin biosynthesis (e.g., PYS, PDS1, and PSD2), underscoring the negative effects of high temperature on P. tricornutum. Interestingly, genes associated with cis-zeatin biosynthesis and cytokinesis signaling pathways exhibited increased expression under high-temperature conditions, indicating a potential role of cis-zeatin signaling in response to elevated temperatures. Content measurements confirm that high temperature enhances cis-zeatin content. Furthermore, the exogenous addition of cytokinesis mimetics or inhibitors significantly affected P. tricornutum's high-temperature resistance. Overexpression of the cis-zeatin biosynthetic enzyme gene tRNA DMATase enhanced P. tricornutum's resistance to high-temperature stress, while genetic knockout of tRNA DMATase reduced its resistance to high temperatures. Therefore, this research not only uncovers a novel mechanism for high-temperature resistance in P. tricornutum but also offers a possible alga species that can withstand high temperatures for the industrial production of fucoxanthin, offering valuable insights for practical utilization.IMPORTANCEThis study delves into Phaeodactylum tricornutum's response to high-temperature stress, specifically focusing on cis-zeatin. We uncover inhibited growth, reduced fucoxanthin, and significant cis-zeatin-related gene expression under high temperatures, highlighting potential signaling mechanisms. Crucially, genetic engineering and exogenous addition experiments confirm that the change in cis-zeatin levels could influence P. tricornutum's resistance to high-temperature stress. This breakthrough deepens our understanding of microalgae adaptation to high temperatures and offers an innovative angle for industrial fucoxanthin production. This research is a pivotal step toward developing heat-resistant microalgae for industrial use.

Changes in global carbon use efficiency in the 21st century and the potential controlling factors

Extensive studies have demonstrated the spatiotemporal changes in carbon use efficiency (CUE) and its driving factors over the past three decades. However, how the global CUE will change and to what extent the CUE is affected by the dominant factor in this century is still unclear. Herein, based on CMIP6 model outputs, we estimated the situation and change trends of CUE in baseline (1982–2014) and future (2015–2100), and identified the controlling factor of CUE variation by boosted regression tree. Further, we predicted the CUE-controlling factor sensitivity (S value, referring to higher/lower controlling factor producing more/less CUE) and its variation under four representative pathways, and revealed the relationship between S value and social economy. Results showed decreased CUE at the end of the 21st century, especially in the SSP5-8.5, its decline rate of CUE is 1.2 × 10−2 ± 5.2 × 10−4/decade, which is 10 times higher than that in the SSP1-2.6. Spatially, 56.9%, 74.5%, 83.1%, and 88.6% of the global land will exhibit a decreased CUE under the SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5 scenarios, and primarily concentrates at the middle-high latitudes of the Northern Hemisphere (30°–60° N). Except in Africa, temperature is the controlling factor for CUE variation, and the S value decreases over time, indicating an enhanced inhibitory effect of temperature on CUE. The turning time of S value change will advance with increases in CO2 emission, presenting prolonged high-temperature stress of vegetation ecosystem under high-emission scenarios. A threshold effect can be found between S value change and precipitation, and the precipitation threshold is higher under the SSP5-8.5 scenario. The negative effect of temperature on CUE is attenuated by economic development and population control but this effect diminishes with rising CO2 concentrations; in the future, developing clean energy and formulating population management policies can be used to enhance the carbon sink ability of the global ecosystem.

Stress-strain state of steel corrugated I-beams prestressed by flange drawing

The material distribution in structures is an urgent scientific and technical problem. Corrugated and prestressed steel structures are efficient and reliable.Purpose: The aim of this paper is to study the operation of steel I-beam with a thin corrugated wall, prestressed by flange drawing.Methodology/approach: Finite element modeling of beams with corrugated and flat walls (models with flat wall, transversely corrugated wall, downward corrugation at an angle of inclination 20 degrees, ascending corrugation at an angle of inclination 20 degrees). The proposed method is used for prestressing the lower beam flange using negative temperature effects. Numerical experiments in LIRA-SAPR software allow to obtain the stress distribution isofields and deformation patterns. A comparative analysis of the stress-strain state.Research findings: The normal stress distribution over flanges of corrugated beams with and without prestress under the external load has low difference. Prestress produces significant deflections of structures and the greatest deflection of the beam with ascending corrugations.

Study of the Methane Adsorption Characteristics in a Deep Coal Reservoir Using Adsorption Potential Theory

The gas adsorption characteristics in deep coal reservoirs are the focus of deep coalbed methane geology research. In order to reveal the adsorption characteristics in deep coal reservoirs and quantitatively characterize the amount of adsorbed methane in the deep coal seams, four coals were collected from the Permian Longtan Formation in southern Sichuan Province. Methane isothermal adsorption tests were carried out on the collected coal samples at 30 °C. The adsorption characteristic curve was established based on the data of the isothermal adsorption. The adsorption potential theory was used to predict the isothermal adsorption curves under different temperatures and the evolutionary relationship between the methane adsorption capacity and the coal seam burial depth in the C17 and C25 coal seams of the Permian in southern Sichuan Province, China. The results showed that the methane isothermal adsorption curve at 30 °C belonged to the Type I isotherm adsorption curve. The methane isothermal adsorption curves for various samples at 45 °C, 60 °C, and 75 °C were predicted based on the uniqueness of the methane adsorption characteristic curve. The amount of adsorbed gas in deep coal reservoirs was comprehensively controlled by pressure and temperature. The pressure showed a positive effect on the amount of methane adsorbed, while the temperature showed a negative effect on the adsorption of methane. The negative effect of temperature became more significant with the increase in pressure. The results of the study are beneficial for further promoting the exploration and development of deep coalbed methane in the southern Sichuan Province of China.

Numerical simulation of frost heaving damage of earth-rock dam berms in cold regions with thermo-hydro-mechanical coupling

In order to investigate the freezing damage problem of berms of earth-rock dams in cold regions, an earth-rock dam in a cold region was selected as the research object in this study. A finite element model, considering the effect of thermo-hydro-mechanical coupling, has been developed to solve the problem by combining the characteristics of the earth-rock dam. The whole process of freezing damage of berms under the influence of the reservoir level and the water migration of the dam filling was investigated, and the laws in temperature, humidity and displacement of earth-rock dams were analyzed. The calculated displacement field was then compared with the measured frozen deformation data to validate the results of the finite element simulation. The results showed that the freezing influence range of the dam slope was about 2 m, the range of temperature influence on the dam slope mainly depended on the depth of freezing, and the temperature change in the shallow range (0–2 m) of the dam slope was influenced by the outside air temperature. Also, the internal temperature of the dam body was small relative to the shallow dam slope, and there was a certain hysteresis. In addition, the effect of negative temperature was such that the shallow pore water phase of the dam slope turned into ice, manifesting macroscopically as a reduction in unfrozen water content. Water phase change, water migration from the dam filling to the dam slope, and the movement of the ice peak towards the dam body were found to be the main causes of berm freezing and expansion damage. The calculated amount expansion (due to freezing) of the dam slope was found to be in the range of 20–30 cm with a maximum value of 36 cm, which was consistent with the measured results. It was also found that the freezing and expansion damage of the berm is mainly caused by the joint action of freezing and expansion of the soil and rock mixture such as gravel bedding and dam filling, as well as the ice thrust force. It is expected that the results of this research can provide a basis for the design of berms of earth-rock dams in cold regions.

Effect of late spring frosts on the growth and development of garden strawberry

The paper presents the results of research for 2022–2023, as well as the analysis of the effect of prolonged negative late spring temperatures on garden strawberry on May 8-12, 2023. The research was aimed at evaluating garden strawberry varieties for a complex of economically valuable characteristics after exposure to prolonged late spring frosts on May 8–12, 2023. Objects of study included 14 garden strawberry varieties of foreign selection: NF 421, ‘Festivalnaya romashka’, ‘Florida Festival’, ‘Verona’, ‘Dely’, ‘Joli’, ‘Senga Sengana’ (k), ‘Sweetheart’, ‘Syria’, ‘Cabot’, ‘Elianni’, ‘Malvina’ and 2 varieties selected by the Institute: ‘Zvezdochka’ (k), ‘Zhanna’. The plants were planted on May 6, 2022, the survival rate accounted for 100%. The research was conducted in the Research Institute of Horticulture and Medicinal Plants “Zhigulyovskie sady” (Samara, Russia) on the collection variety plot in accordance with the generally accepted program and methodology of varietal study of fruit, berry and nut crops. The analysis of weather conditions for 2022–2023 was performed using the data of the Volga Department for Hydrometeorology and Environmental Monitoring (UGMS), with additional data obtained from the temperature and humidity control system located on the test plot in Malaya Tsarevshchina, Krasnoyarsky District, Samara Oblast. The varieties ‘Verona’, ‘Zvezdochka’ (k), ‘Cabot’, ‘Sweetheart’, ‘Festivalnaya Romashka’, and ‘Malvina’ demonstrated the highest resistance to late spring frosts according to the complex of characteristics. The main part of the varieties had 28-33% damage to flowers and buds. The highest damage figure was revealed in the variety of the average maturity period NF 421 and the early variety ‘Zvezdochka’ (k). The late variety ‘Malvina’ did not suffer from frost.The lowest degree of fruit deformation was observed in the varieties ‘Sweetheart’, ‘Zvezdochka’ (k), and ‘Malvina’. The greatest degree of freezing after exposure to low temperatures on May 8-12 was observed in the varieties ‘Dely’, ‘Joli’, ‘Florida Festival’ and ‘Elianni’. The best adaptive capacity according to the results of overall plant condition for the period 2022-2023 was shown by the varieties ‘Verona’, ‘Zvezdochka’ (k), ‘Senga Sengana’ (k), ‘Cabot’, ‘Sweetheart’, ‘Syria’. The highest average berry weight was recorded in NF 421 (19.5 g/bush). The highest productivity was observed in later ripening varieties – ‘Malvina’ (261.4 g/bush) and ‘Cabot’ (241.0 g/ bush), as well as in the control variety ‘Seng Sengana’ (k) (197.1 g/bush). The lowest indicators were reported in ‘Dely’ (50.1 g/bush) and ‘Florida Festival’ (29.0 g/bush). The genotype was revealed to influence the resistance to low late spring temperatures and recovery ability of plants after late spring frosts.

Synergistic effect of positive temperature coefficient and thermally conductive micro‐nano fillers on electrical and thermal properties of epoxy resin

AbstractThis study investigates the effect of positive temperature coefficient (PTC) fillers, i.e., barium strontium titanate (BST‐60) and nano hexagonal boron nitride (h‐BN) fillers, on thermal and dielectric insulation properties of epoxy (EP). The electrical resistivity, DC breakdown strength, space charge, thermal conductivity, thermogravimetric analysis, and glass transition temperature (Tg) of EP composites were measured. Results indicate that, below curie temperature, the EP composites containing 0.5 and 1 wt% of BST and 5 wt% of h‐BN have superior electrical resistivity, breakdown strength, and thermal conductivity. However, above curie temperature, the EP composites containing 2 and 2.5 wt% of BST and 5 wt% of h‐BN have superior insulation properties than the pure EP and other composites. While the thermal properties of EP improve with an increase in h‐BN loading to 10 wt%, its dielectric properties are slightly compromised due to the presence of tiny defects in the composite material. It is hypothesized that the BST‐60 suppresses the negative temperature coefficient effect (NTC) of EP by regulating the electrical resistivity above the curie point, whereas nano h‐BN enhances the thermal conductivity of EP by constructing a heat dissipation path. The proposed mechanism for charge dynamics along with heat conduction‐dissipation explains the fillers' behavior at different temperatures.Highlights Analysis of epoxy composites with polydopamine‐modified BST and h‐BN fillers. PTC fillers are used to mitigate the negative temperature effect of epoxy. Optimal fillers wt% improves dielectric and thermal properties. This study shows that optimized epoxy composites can be used for packaging.

Change and influence of agroclimatic conditions on oat yield in Yakutia

The results of the dynamics analysis of multi-year meteorological indicators and study of their influence on the yield of the released oat varieties in different agroclimatic zones of Yakutia are presented. It is shown that in the period from 1960 to 2021 the mean annual air temperature in Central Yakutia (Pokrovsk meteorological station) increased annually by 0.045 °C, from 1999 to 2021 – by 0.088 °C, the number of dry years in June increased from 67 to 92% due to a 21% increase in years with medium (HTC = 0.41-0.60) and very strong (HTC < 0.21) drought. In July, drought was recorded in 50% of the years, in August – in 38%. In all agroclimatic zones in the period from 2014 to 2021 for June – August the average daily air temperature annually increased by 0.16...0.34 °С and their sum by 14...28 °С, with precipitation decreasing by 3-16 mm and HTC value by 0.04-0.12 units. Climate change from 2014 to 2021 was 3 to 8 times more intense than from 1999 to 2022. There was a strong variability of yields of the released oat varieties in each agroclimatic zone: Central – from 0.38 to 2.14 t/ha (V = 60–73%), Zarechnaya – from 0.31 to 3.55 t/ha (V = 41–49%), Srednelenskaya – from 1.51 to 4.66 t/ha (V = 30–36%). The greatest annual decrease in grain yield of oat varieties (by 0.25–0.26 t/ha) was observed in arid agroclimatic zones – Central (Yakutsk SCTS) and Zarechnaya (Megino-Kangalassky SCTS) – compared to the wetter Srednelenskaya zone (Olyokminsky SCTS – by 0.10 t/ha). More significant influence on the yield in the Central and Zarechnaya zones was made by precipitation and HTC of the growing season (r = 0.77...0.84), in the Srednelenskaya zone – by temperature (r = – 0.79). Negative effect of temperature on the yield in the Central zone was observed in June (r = – 0.83), Zarechnaya zone - in July (r = – 0.83), in the Srednelenskaya zone – in August (r = –0.86). Precipitation and HTC had the greatest influence on the yield in the Central zone in June and July (r = 0.56...0.59), Zarechnaya zone – July and August (r = 0.60...0.76). In the Srednelenskaya zone the relationship of the yield with precipitation and HTC in June and July was positive (r = 0.23...0.37), in August – negative (r = – 0.57...– 0.71). Significant variability in grain yields of the released oat varieties indicates the variability of weather conditions and the need to cultivate oat varieties that provide a more stable yield in different agroclimatic zones of Yakutia.

Tropical bloom-forming mesoalgae Cladophoropsis sp. and Laurencia sp.-responses to ammonium enrichment and a simulated heatwave.

Algal blooms are increasing worldwide, driven by elevated nutrient inputs. However, it is still unknown how tropical benthic algae will respond to heatwaves, which are expected to be more frequent under global warming. In the present study, a multifactorial experiment was carried out to investigate the potential synergistic effects of increased ammonium inputs (25 μM, control at 2.5 μM) and a heatwave (31°C, control at 25°C) on the growth and physiology (e.g., ammonium uptake, nutrient assimilation, photosynthetic performance, and pigment concentrations) of two bloom-forming algal species, Cladophoropsis sp. and Laurencia sp. Both algae positively responded to elevated ammonium concentrations with higher growth and chlorophyll a and lutein concentrations. Increased temperature was generally a less important driver, interacting with elevated ammonium by decreasing the algaes'%N content and N:P ratios. Interestingly, this stress response was not captured by the photosynthetic yield (Fv/Fm) nor by the carbon assimilation (%C), which increased for both algae at higher temperatures. The negative effects of higher temperature were, however, buffered by nutrient inputs, showing an antagonistic response in the combined treatment for the concentration of VAZ (violaxanthin, antheraxanthin, zeaxanthin) and thalli growth. Ammonium uptake was initially higher for Cladophoropsis sp. and increased for Laurencia sp. over experimental time, showing an acclimation capacity even in a short time interval. This experiment shows that both algae benefited from increased ammonium pulses and were able to overcome the otherwise detrimental stress of increasingly emerging temperature anomalies, which provide them a strong competitive advantage and might support their further expansions in tropical marine systems.

Effects of Beauveria bassiana (Bals.-Criv.) Vuill. on the growth of Vigna unguiculata (Linnaeus) Walpers under laboratory and field conditions, and the resistance of the plant to insect attack

Beauveria bassiana (Bals.-Criv.) Vuill. is an established biocontrol agent in laboratory, but studies have shown negative effects of temperature and Ultraviolet radiation on its potential in vitro. Nevertheless, there is a lack of studies about its endophytic colonization in vivo, especially in field conditions in cowpea [Vigna unguiculata (L.) Walp.]. In this sense, this study aimed to evaluate the effects of B. bassiana applied to cowpea seed on the growth of the plants under laboratory and field conditions, and on their resistance to insect attack. Cowpea seeds were treated with suspension of 5 x 108 conidia/mL of B. bassiana. The plants were cultivated in two independent conditions (laboratory and field). The resistance to attack of the pest in field conditions was assessed by monitoring weekly the plants three times a week during 12 weeks, from the initial vegetative to the reproductive stage. According to the results, in laboratory conditions, there were significant differences among the inoculated and control plants for the variables of height of the plants (31.17 cm for treatment and 23.00 cm for control plants) and dry mass of the root (2.38 g for treatment and 0.97 g for control plants). In field conditions, the observed pest insects were miner fly [Liriomyza sp.] (Diptera: Agromyzidae), Cerotoma arcuata Olivier, 1791 (Coleoptera: Chrysomelidae), aphid (Aphis craccivora Koch, 1854) (Hemiptera: Aphididae) and the polyphagous hemipteran [Crinocerus sanctus (Fabricius, 1775)] (Hemiptera: Coreidae). The treated plants were less affected than control plants by these pests, especially at the beginning of the vegetative phase.

The impact of high temperatures on performance in work-related activities

High temperatures can have a negative effect on work-related activities because workers may experience difficulties concentrating or have to reduce effort in order to cope with heat. We investigate how temperature affects performance of professional tennis players in outdoor singles matches in big tournaments. We find that performance significantly decreases with ambient temperature. This result is robust to including wind speed and air pollution in the analysis. There are no differences between men and women. However, there is some heterogeneity in the magnitude of the temperature effect in other dimensions. In particular, we find that the temperature effect is smaller when there is more at stake. Our findings also suggest that the negative temperature effect is smaller if the heat lasts, i.e. there is some adaptation to high temperatures.

Experimental studies and computational exploration on an exceptionally salt/condensate resistant gas well foaming mixture compromising amino-betaine-ammonium surfactants and dodecanol

Liquid accumulation in natural gas wells is typically addressed by foam-based deliquification. This study systematically investigated the development of a green and cost-effective foaming mixture comprising lauramidopropyl trimethylammonium chloride (LATC), lauramidopropyl betaine (LAPB), sodium lauroyl glutamate (SLG) and dodecanol (LA). Properly combined LATC/SLG/LAPB/LA mixture demonstrated synergistic effects in enhancing foam generation, foam stabilization and liquid unloading. Remarkably, the LATC/SLG/LAPB/LA foam exhibited exceptional performance in unloading liquid, even at a condensate fraction of up to 50 %. Adding a chelator (NTA) to LATC/SLG/LAPB/LA further improved the foaming efficiency and liquid unloading performance at salinity levels of up to 33 × 104 mg/L, which was likely the highest salt tolerance according to the available literature. The negative effect of temperature on the performance of LATC/SLG/LAPB/LA foam was resolved by adding 15 % methanol. At 90 °C, almost all the liquid can be removed from the column by the LATC/SLG/LAPB/LA foam, which produced a liquid unloading efficiency of 90 % and a foaming efficiency of 100 %. Surface tension, viscosity and morphological analysis supported the observed synergistic effects, while molecular dynamic simulations revealed the mechanisms of the excellent salt/condensate resistance of the LATC/SLG/LAPB/LA foam. These findings demonstrated the promising potential of the LATC/SLG/LAPB/LA foam in gas well deliquification.

Pressure and temperature dependent kinetics and the reaction mechanism of Criegee intermediates with vinyl alcohol: a theoretical study.

Criegee intermediates (CIs), the key intermediates in the ozonolysis of olefins in atmosphere, have received much attention due to their high activity. The reaction mechanism of the most simple Criegee intermediate CH2OO with vinyl alcohol (VA) was investigated by using the HL//M06-2X/def2TZVP method. The temperature and pressure dependent rate constant and product branching ratio were calculated using the master equation method. For CH2OO + syn-VA, 1,4-insertion is the main reaction channel while for the CH2OO + anti-VA, cycloaddition and 1,2-insertion into the O-H bond are more favorable than the 1,4-insertion reaction. The 1,4-insertion or cycloaddition intermediates are stabilized collisionally at 300 K and 760 torr, and the dissociation products involving OH are formed at higher temperature and lower pressure. The rate constants of the CH2OO reaction with syn-VA and anti-VA both show negative temperature effects, and they are 2.95 × 10-11 and 2.07 × 10-13 cm3 molecule-1 s-1 at 300 K, respectively, and the former is agreement with the prediction in the literature.

Negative-temperature pressure in black holes

The concept of negative temperature is unique to quantum physics and describes systems that are hotter than any positive-temperature system. For decades, negative temperatures have been shown in a number of spin systems, but experiments only recently demonstrated atomic ensembles with negative temperatures in their motional degrees of freedom. An observed behavior of such negative-temperature ensembles is that despite highly attractive forces between an arbitrary number of particles, there is a self-stabilization against collapse. Negative temperatures are only possible in quantum systems because there exists upper bounds on the energy of particles —a property not found in classical physics. Here we consider whether event horizons set up similar upper limits within black holes, giving rise to negative-temperature systems just within event horizons. Combining black-hole thermodynamics with experimentally observed negative-temperature effects could imply a quantum-based outward pressure in black holes.

Impact of Meteorological Parameters on Solar Radiation over Langtang National Park, Nepal

The main objective of this research is to study the impact of meteorological parameters on atmospheric turbidity index on Langtang National Park (28.2112° N, 85.5663° E, 3862 m asl) for a period of one year (2018). Daily data of Aerosol optical depth (AOD) and meteorological parameters are obtained from AERONET and NASA website respectively. The maximum and minimum values of direct solar radiation (IB) during the study period are found 1286 ± 24 W/m2 in January and 1123 ± 3 W/m2 in August respectively. The maximum and minimum value of diffuse solar radiation (ID) is found 119 ± 21 W/m2 in April and 59 ± 2 W/m2 in August respectively. The annual average of direct solar radiation and diffuse solar radiation are found 1202 ± 63 W/m2 and 90 ± 20 W/m2 respectively. There is a negative effect of maximum temperature, minimum temperature, dew point, relative humidity, water contend and rainfall on IB, but no significant effect of those parameters on ID. The result of this research work is beneficial for the further identification, impact and analysis of solar radiation at different places with same geographical and meteorological condition. The study of solar radiation is important for energy harvesting and agriculture.

Benefits of watermelon juice and ascorbic acid supplementation on Institut de Sélection Animale brown layers managed under hot climate

Loss of homeostasis and poor egg production are common in laying hens during hot season. These negative effects of extreme ambient temperature have resulted in great economic losses to poultry farmers in the tropical regions. This study investigated benefits of supplementing watermelon juice (WJ) and ascorbic acid (AA) to ISA Brown (IB) hens managed under hot climate on productive performance and some hormonal responses. Ninety-six IB pullets aged 34 weeks were randomly allotted to four groups (C, T1, T2, and T3), each containing 24 in triplicates. The control group (C) was given water with neither WJ nor AA. Water given to groups T1, T2 was supplemented with 20% and 40% WJ, respectively, while T3 was supplemented with 200mg AA/litre of water. The results show a significant (P≤0.05) increase in water intake in T3 compared to other groups. Total egg production, daily egg production and hen-day egg production were significantly (P≤0.05) improved by the supplements, as total egg weights improved in T1:(272.2 ± 35.16g) and T2:(272.1 ± 35.06g) compared to C:(212.2 ± 25.06g) and T3:(238.5 ± 19.23g). The supplements caused 24.46%, 22.70% and 9.43% rise in percentage egg production in groups T1, T2, and T3 respectively. Serum corticosterone (C:10.88 ± 1.12; T1:10.20 ± 1.06; T2:9.61 ± 0.792; T3:7.23 ± 2.36ng/mL) and thyroxine levels (C:1.45 ± 0.562; T1:0.41 ± 0.109; T2:0.39 ± 0.367; T3:0.60 ± 0.489μg/dL) decreased significantly (P≤0.05) in supplemented layers, while serum prolactin and triiodothyronine differed non-statistically. In conclusion, WJ and AA supplementation ameliorated heat stress in IB layers managed under hot climate as it significantly lowered corticosterone and improved egg production. Therefore, supplementing 20%, 40%WJ or 200mg AA/litre in water is recommended for managing heat stress in IB layer chickens

Influence of negative temperature hardening on hydration, pore structure evolution and strength development of cement paste

The pre-cured 24-h demolded cement pastes were directly cured at −5 °C and +20 °C for different ages to investigate the influence of negative temperature hardening on hydration, pore structure evolution, and strength development. Thermogravimetric (TG) results show that the inhibition effect of negative temperature hardening on the hydration degree and C–S–H gel content is different. As the hydration age increases to 120 days, the hydration degree and gel-space ratio of negative temperature hardening cement paste can reach the positive temperature hardening level of 120 days, while the C–S–H gel content is still lower than the positive temperature hardening level of 120 days. Mercury intrusion porosimetry (MIP) results indicated that negative temperature hardening increases all types of pore volumes, especially the pore volume of <10 nm. Similar to the hydration degree, by giving sufficient negative temperature hardening time (120 days), the pore characteristic parameters of negative temperature hardening cement pastes can approach the level of 120-day positive temperature hardening. Also, the fractal analysis shows that negative temperature hardening increases the proportion of large-diameter pores in the range of <100 nm, and decreases the proportion of large-diameter pores in the range of >3000 nm. In addition, the micro-mechanisms of limiting strength development are different at different negative temperature hardening stages. The early strength development is affected by the coupled effects of hydration and pore structure, while the later strength development is limited due to the lower C–S–H gel content.

Fe/amorphous-Al2SiO5 composites fabricated by low-temperature solid-phase reaction densification achieve synergistically enhanced structural and soft magnetic properties

To date, an urgent problem for various metal-based soft magnetic composites (SMCs) is that it is difficult to simultaneously achieve high strength and optimum magnetic performance, which actually restricts their large-scale applications in many electromagnetic fields. In this work, we have tried to resolve this basic problem by proposing a new concept of low-temperature solid-phase reaction densification instead of conventional particle-deformation densification to fabricate high-performance metal-based SMCs. Specifically, fully-densified nanoscale amorphous Al2SiO5 coating layers are formed through a solid phase reaction at 500 °C between initially-prepared nano-sized amorphous SiO2 and amorphous Al2O3, and meanwhile coated in situ on the surface of deformed Fe to fabricate novelly-structured Fe/amorphous-Al2SiO5 SMCs. The low-temperature solid-phase reaction for fabrication of Fe/amorphous-Al2SiO5 SMCs can avoid negative effects of high processing temperature for conventional metal-based SMCs on their structure and magnetism resulting in their high strength, increased resistivity, low core loss and high saturation magnetic inductions. Thus, Fe/amorphous-Al2SiO5 SMCs show synergistically enhanced structural and soft magnetic properties, which exceed those of most conventional metal-based SMCs. This work also provides a special and useful insight into the design and applications of metal-based composites needing both functional and structural properties.