Thermal Limits Research Articles

Flexibility in thermal requirements: a comparative analysis of the wide-spread lizard genus Sceloporus.

Adaptation or acclimation of thermal requirements to environmental conditions can reduce thermoregulation costs and increase fitness, especially in ectotherms, which rely heavily on environmental temperatures for thermoregulation. Insight into how thermal niches have shaped thermal requirements across evolutionary history may help predict the survival of species during climate change. The lizard genus Sceloporus has a widespread distribution and inhabits an ample variety of habitats. We evaluated the effects of geographical gradients (i.e. elevation and latitude) and local environmental temperatures on thermal requirements (i.e. preferred body temperature, active body temperature in the field, and critical thermal limits) of Sceloporus species using published and field-collected data and performing phylogenetic comparative analyses. To contrast macro- and micro-evolutional patterns, we also performed intra-specific analyses when sufficient reports existed for a species. We found that preferred body temperature increased with elevation, whereas body temperature in the field decreased with elevation and increased with local environmental temperatures. Critical thermal limits were not related to the geographic gradient or environmental temperatures. The apparent lack of relation of thermal requirements to geographic gradient may increase vulnerability to extinction due to climate change. However, local and temporal variations in thermal landscape determine thermoregulation opportunities and may not be well represented by geographic gradient and mean environmental temperatures. Results showed that Sceloporus lizards are excellent thermoregulators, have wide thermal tolerance ranges, and the preferred temperature was labile. Our results suggest that Sceloporus lizards can adjust to different thermal landscapes, highlighting opportunities for continuous survival in changing thermal environments.

Temporally-resolved decomposition of Ti0.12Al0.21B0.67 thin films at 1000 °C

The thermal stability of stoichiometric Ti0.12Al0.21B0.67 thin films synthesized by magnetron sputtering was investigated by vacuum annealing at 1000 °C for 1 and 3 h. The as-deposited and post-annealed films were compared regarding changes in chemical composition, phase formation, and morphology.X-ray diffraction (XRD) data indicate the formation of a single-phase solid solution in the as-deposited Ti0.12Al0.21B0.67 thin film. After annealing for 1 h, scanning transmission electron microscopy (STEM), energy-dispersive X-ray mapping (EDX), and atom probe tomography (APT) investigations reveal segregation into Al- and Ti-rich (Ti,Al)B2 domains, consistent with spinodal decomposition. Furthermore, the formation of AlB12 with a concomitant reduction in Al concentration from 20.9 to 16.8 at. %, likely by evaporation, indicate the decomposition of Al-rich (Ti,Al)B2 domains during annealing for 1 h.Analysis of the film after annealing for 3 h shows evidence for continued spinodal decomposition as well as for further decomposition of Al-rich (Ti,Al)B2 domains, leading besides the formation of AlB12 to a reduction in Al concentration to 12.5 at. % by Al evaporation. The observed phase formation trend during in situ transmission electron microscopy (TEM) studies at 1100 °C is consistent with the above discussed decomposition processes. The here identified thermal stability limit, revealed with spatially resolved structure and composition probes, confines the application temperature range of Ti0.12Al0.21B0.67 in vacuum to temperatures <1000 °C and underlines that thermal stability investigations solely based on XRD data result in an overestimated thermal stability.

Anticipating change: The impact of simulated seasonal heterogeneity on heat tolerances along a latitudinal cline.

An understanding of thermal limits and variation across geographic regions is central to predicting how any population may respond to global change. Latitudinal clines, in particular, have been used to demonstrate that populations can be locally adapted to their own thermal environment and, as a result, not all populations will be equally impacted by an increase in temperature. But how robust are these signals of thermal adaptation to the other ecological challenges that animals commonly face in the wild? Seasonal changes in population density, food availability, or photoperiod are common ecological challenges that could disrupt patterns of thermal tolerance along a cline if each population differentially used these signals to anticipate future temperatures and adjust their thermal tolerances accordingly. In this study, we aimed to test the robustness of a cline in thermal tolerance to simulated signals of seasonal heterogeneity. Experimental animals were derived from clones of the Australian water flea, Daphnia carinata, sampled from nine distinct populations along a latitudinal transect in Eastern Australia. We then factorially combined summer (18 h light, 6 h dark) and winter (6 h light, 18 h dark) photoperiods with high (5 million algal cells individual-1 day-1) and low (1 million algal cells individual-1 day-1) food availabilities, before performing static heat shock assays to measure thermal tolerance. We found that the thermal tolerances of the clonal populations were sensitive to both measures of seasonal change. In general, higher food availability led to an increase in thermal tolerances, with the magnitude of the increase varying by clone. In contrast, a switch in photoperiod led to rank-order changes in thermal tolerances, with heat resistance increasing for some clones, and decreasing for others. Heat resistance, however, still declined with increasing latitude, irrespective of the manipulation of seasonal signals, with clones from northern populations always showing greater thermal resistance, most likely driven by adaptation to winter thermal conditions. While photoperiod and food availability can clearly shape thermal tolerances for specific populations, they are unlikely to overwhelm overarching signals of thermal adaptation, and thus, observed clines in heat resistance will likely have remained robust to these forms of seasonal heterogeneity.

Modelling thermal reaction norms for development and viability in Drosophila suzukii under constant, fluctuating and field conditions

Phenological models for insect pests often rely on knowledge of thermal reaction norms. These may differ in shape depending on developmental thermal conditions (e.g. constant vs. fluctuating) and other factors such as life-stages. Here, we conducted an extensive comparative study of the thermal reaction norms for development and viability in the invasive fly, Drosophila suzukii, under constant and fluctuating thermal regimes. Flies, were submitted to 15 different constant temperatures (CT) ranging from 8 to 35 °C. We compared responses under CT with patterns observed under 15 different fluctuating temperature (FT) regimes. We tested several equations for thermal performance curves and compared various models to obtain thermal limits and degree-day estimations. To validate the model's predictions, the phenology was monitored in two artificial field-like conditions and two natural conditions in outdoor cages during spring and winter. Thermal reaction norm for viability from egg to pupa was broader than that from egg to adult. FT conditions yielded a broader thermal breadth for viability than CT, with a performance extended towards the colder side, consistent with our field observations in winter. Models resulting from both CT and FT conditions made accurate predictions of degree-day as long as the temperature remained within the linear part of the developmental rate curve. Under cold artificial and natural winter conditions, a model based on FT data made more accurate predictions. Model based on CT failed to predict adult's emergence in winter. We also document the first record of development and adult emergence throughout winter in D. suzukii. Population dynamics models in D. suzukii are all based on summer phenotype and CT. Accounting for variations between seasonal phenotypes, stages, and thermal conditions (CT vs. FT) could improve the predictive power of the models.

Flies on the rise: acclimation effect on mitochondrial oxidation capacity at normal and high temperatures in Drosophila melanogaster.

Increased average temperatures and extreme thermal events (such as heatwaves) brought forth by climate change impose important constraints on aerobic metabolism. Notably, mitochondrial metabolism, which is affected by both long- and short-term temperature changes, has been put forward as an important determinant for thermal tolerance of organisms. This study examined the influence of phenotypic plasticity on metabolic and physiological parameters in Drosophila melanogaster and the link between mitochondrial function and their upper thermal limits. We showed that D. melanogaster acclimated to 15°C have a 0.65°C lower critical thermal maximum (CTmax) compared with those acclimated to 24°C. Drosophila melanogaster acclimated to 15°C exhibited a higher proportion of shorter saturated and monounsaturated fatty acids, concomitant with lower proportions of polyunsaturated fatty acids. No mitochondrial quantitative changes (fractional area and number) were detected between acclimation groups, but changes of mitochondrial oxidation capacities were observed. Specifically, in both 15°C- and 24°C-acclimated flies, complex I-induced respiration was increased when measured between 15 and 24°C, but drastically declined when measured at 40°C. When succinate and glycerol-3-phosphate were added, this decrease was however compensated for in flies acclimated to 24°C, suggesting an important impact of acclimation on mitochondrial function related to thermal tolerance. Our study reveals that the use of oxidative substrates at high temperatures is influenced by acclimation temperature and strongly related to upper thermal tolerance as a difference of 0.65°C in CTmax translates into significant mitochondrial changes.

DC bias impact analysis on the capability of power transformer and failure risks

A significant transition towards low-carbon, renewable energy sources and technological adaptation is mandatory in the present scenario to address climate change and achieve a sustainable energy system. Aligned with the upgradation in technology, as the need for efficient and smart energy grows, power electronics are being extensively used in power systems. Various factors can affect the pervasive use of power electronics associated with power transformers, thereby introducing the DC bias in the system. DC bias in the transformer leads to a shift in operating point, a rise in excitation current and a generation of harmonics. This causes an increase in core losses and temperature, resulting in exceeding the thermal limits and leading to transformer failure. Consequently, there is an emergency need to understand the DC bias capability of power transformers that aims at optimal transformer selection without being overrated. This research employs Ansys maxwell software to model and simulate a 500 kVA, 11kV/420V three-phase power transformer. The experimental investigation is carried out through a scale-down value of a 5 kVA laboratory prototype. The research findings revealed a significant negative impact of DC bias on power transformer capabilities that could be detrimental to its performance, health and lifespan. The analysis results provide valuable insights for the design engineer during the initial stages of designing a high-performance, cost-effective transformer with a low failure rate.

Thermal tolerance for the tropical clawed frog, Xenopus tropicalis with comments on comparative methods for amphibian studies

Thermal tolerance data are important for identifying the potential range of non-native species following introduction and establishment. Such data are particularly important for understanding invasion risks of tropical species introduced to temperate climates and identifying whether they can survive outside tropical regions. A breeding population of the tropical clawed frog (Xenopus tropicalis) was recently discovered in west-central Florida, U.S.A. This fully aquatic species is native to the rainforest belt of west Africa and has not been documented outside its native range. Because of the lack of invasion history, data are sparse on the thermal limits for this species. We used chronic lethal and critical thermal methodologies to investigate thermal tolerance on adult stages and critical thermal methods on tadpoles. Because of our use of both chronic and critical methodologies, we also examined the literature to reveal common methods used to investigate thermal minimum and maximum temperature in amphibians, which were found to be dominated by the critical maximum. Chronic lethal temperatures for adult X. tropicalis were 9.73 °C and 36.68 °C. Critical temperatures were affected by acclimation temperature and life stage; adults were more tolerant of extreme temperatures. Based on these critical thermal data and the fact that breeding tends to occur when temperatures are suitable for survival, tadpole stages are unlikely to be affected by extreme temperatures. Instead, range expansion in Florida will likely be limited by the adult stages. Our findings indicate that the tropical clawed frog could occupy much of southern Peninsular Florida and other tropical and subtropical regions worldwide.

Large‐scale deviations between realized and fundamental thermal niches in global seaweed distributions

AbstractAimClimate change has profound effects on species' distributions, and it is crucial to understand how well physiological limits correspond to distribution patterns to provide realistic estimations of future range shifts and/or extinctions. Seaweeds are foundation species of global coastal ecosystems, and sea surface temperature is a main predictor to explain their distributions and redistributions under global warming. We here test the hypothesis that, in contrast to other marine ectotherms, physiological knowledge of temperature niches is a weak predictor for seaweed distributions.LocationGlobal.Time PeriodPresent (1984–2019).TaxaSeaweeds.MethodsWe analysed the predictive power of physiological temperature limits to predict real‐world distributions in 126 globally distributed seaweed species with linear and generalized linear mixed models.ResultsIn 72% of the species, there was a difference of ≥|2|°C between the physiological and the realized thermal limits. Both, thermal underfilling (distributional thermal limits narrower than the physiological limits) and overfilling (distributional thermal limits wider than the physiological limits) were present. Thus, in only 28% of the species the physiological limits corresponded to the distributional limits. While heat‐tolerance is a significant predictor for upper distributional temperature limits, we found no relationship between cold‐tolerance and lower distributional temperature limits and the latter two seem to be independent.Main ConclusionsPhysiological thermal limits have limited predictive power for seaweed distributions and deviations may be large. Especially cold‐tolerances are a weak predictor, and forecasting of migrations under changing global conditions (e.g. towards the poles) will need special attention. This indicates that responses towards climate change might be highly variable between seaweed species and difficult to predict. Further, nearly 60% of the investigated species had populations which are close to or beyond their reported upper survival limits and are thus probably under threat of eradication by elevation of sea surface temperature.

Thermal-noise-limited ultra-stable laser operated at 698 nm

Ultra-stable lasers are indispensable in high precision measurements. Here we demonstrate an ultra-stable laser system that reaches the thermal noise limit of the optical cavity for the 698 nm clock transition laser of strontium atomic optical clock. This is achieved by locking the frequency of the external-cavity diode laser (ECDL) to a full ULE optical cavity with a length of 10 cm. By suppressing noise such as temperature disturbance, vibration, residual amplitude modulation (RAM), and fiber phase noise, the measured laser linewidth is less than 0.9 Hz. After subtracting the linear drift of 60 mHz/s, the frequency instability of the beat signal reaches 1.2 × 10−15 at 1 s averaging time, which is close to the thermal noise limit of the optical cavity.

Despite plasticity, heatwaves are costly for a coral reef fish

Climate change is intensifying extreme weather events, including marine heatwaves, which are prolonged periods of anomalously high sea surface temperature that pose a novel threat to aquatic animals. Tropical animals may be especially vulnerable to marine heatwaves because they are adapted to a narrow temperature range. If these animals cannot acclimate to marine heatwaves, the extreme heat could impair their behavior and fitness. Here, we investigated how marine heatwave conditions affected the performance and thermal tolerance of a tropical predatory fish, arceye hawkfish (Paracirrhites arcatus), across two seasons in Moorea, French Polynesia. We found that the fish’s daily activities, including recovery from burst swimming and digestion, were more energetically costly in fish exposed to marine heatwave conditions across both seasons, while their aerobic capacity remained the same. Given their constrained energy budget, these rising costs associated with warming may impact how hawkfish prioritize activities. Additionally, hawkfish that were exposed to hotter temperatures exhibited cardiac plasticity by increasing their maximum heart rate but were still operating within a few degrees of their thermal limits. With more frequent and intense heatwaves, hawkfish, and other tropical fishes must rapidly acclimate, or they may suffer physiological consequences that alter their role in the ecosystem.

Heat tolerance and evaporative cooling capacity in an arid-zone elephant shrew

Endotherms vary widely in their capacity to defend sublethal body temperature (Tb) during acute heat exposure. Interspecific variation in the upper thermal limits of small mammals remains poorly studied, particularly in taxa other than bats. We hypothesised that rupicolous elephant shrews (Macroscelidae), on account of their occupancy of above-ground rock crevices in hot habitats and rapid cursorial locomotion, have evolved pronounced heat tolerance capacities. To test this hypothesis, we quantified relationships between Tb, resting metabolic rate (RMR) and evaporative water loss (EWL) in western rock elephant shrews (Elephantulus rupestris) exposed to air temperature (Tair) approaching or exceeding Tb under conditions of low humidity representative of the study population’s arid, winter-rainfall habitat in western South Africa. Our data revealed a pronounced capacity to tolerate Tair > Tb, with E. rupestris tolerating Tair up to 48.0 ± 0.1 °C while defending Tb > 7 °C below Tair (maximum Tb = 41.64 ± 0.16 °C). Three behavioural pathways were employed to dissipate heat: open mouth panting, flattening their body posture, and nose-licking. At the highest experimental Tair values achieved, EWL increased 15.05-fold relative to normothermic levels and heat was dissipated evaporatively at rates equivalent to 174%—240% of metabolic heat production. The heat tolerance limit of Tair = 48 °C in E. rupestris is one of the highest yet recorded in a non-volant small mammal, and our data support the notion that elephant shrews possess a pronounced capacity to avoid lethal hyperthermia during acute heat exposure.

Embryonic and larval development of yellow perch (Perca flavescens) and its sensitivity to incubation temperature.

The ontogenetic development in teleost fish is sensitive to temperature, and the developmental rate has a direct relationship with the environmental temperature within a species' thermal tolerance limit. Temperature determines time to and survival at hatching. Yellow perch is a North American species of ecological and commercial importance, and its phenology is vulnerable to climate change. The embryonic development of yellow perch was comparable to closely related members of the family Percidae. Developmental progression was fastest at 18°C and slowest at 12°C, with medial progression at 15°C. Time to hatch and swim-up, feeding onset, and exogenous feeding phases were different across all incubation temperatures regardless of a gradual post-hatch warming of the 12 and 15°C groups to a common garden temperature of 18°C. Incubation temperature may lower the rate of survival to hatch at 15°C and had complex impacts on developmental abnormalities. Temperature had significant effects on the development rate, time of hatch, survival, and incidence of developmental abnormalities. Early ontogenetic thermal history in ectotherms is an important factor determining phenotypic variation. It will be important to link the thermally induced changes in development described here to the physiological and morphological differences and to link the developmental abnormalities to functional performance.

The need for innovations to secure the future of artisanal mussel farming in the coastal sea of the Gulf of Trieste (Slovenia)

Mariculture along the Slovene coastline is mainly mussel culture operated as a family business; in one case, it is combined with sea bass farming. It started in the early 70 s with cultivation of Mediterranean mussels, while today, the two largest producers incorporate the cultivation of Venus clams and oysters as species with higher economic value on the market. Currently, all mussels and clams produced in Slovenia are sold in the Slovenian, Italian, Croatian and French markets. The production of Mediterranean mussels (Mytilus galloprovincialis) has increased steadily, with the main obstacles being a limited area for cultivation, occasional harmful algal blooms, predation by gilthead seabream and flatworms. In addition, more recent summer heatwaves negatively affected mussel production when seawater reached high temperatures at the thermal limits unsuitable for mussel growth. This study aimed to collect first-hand information about the current mussel production technology, processes and needs to identify opportunities for innovations that could benefit the entire sector (increased knowledge, production yield, reduced workload and effort with administrative issues). The study was based on a semi-structured questionnaire with the owners of mussel farms. Analysis of the questionnaire was supplemented with current knowledge from the field and provided comprehensive insight into a small sector of mussel farming along the Slovenian coast and its possible development in the future.

Thermal tolerance, development, and physiological impacts of climate warming on zoea larvae of brachyuran crabs

Predicted effects of increasing ocean temperatures, due anthropogenic climate change, might be more challenging for early life history stages owing to reduced thermal tolerance. Thus, determining species responses to the projected climate warming conditions on marine ecosystems is essential to access their vulnerability. Here, we experimentally evaluated the effect of increased temperature on larval survival, development time and metabolic responses of two intertidal crab species (Menippe nodifrons and Ucides cordatus). The metabolic rate (measured as oxygen consumption), ammonia excretion and heartbeat rates were measured in standard fashion way, while the coefficient of temperature was obtained as a measure of organism's sensitivity to temperature increase. Critical thermal maximum and minimum, and thermal safety margins were also obtained. The results indicate a decrease in survival probability and development time for both species, from zoea I to zoea III stage, which was seen in higher extent to larvae of M. nodifrons. There is no significant effect of temperature increase on heartbeats and ammonia excretion rates to both species; however, increases in temperature had a differential effect on metabolic responses of two species. In addition, the critical thermal limits for the larval phase were described for the first time, suggesting that larvae of M. nodifrons are more vulnerable and have lower acclimation capacity to warming waters. Although a high sensitivity in metabolism was seen in U. cordatus, this species demonstrates higher thermal tolerance accompanied by a greater physiological plasticity. Our data emphasize that warming of coastal waters may reduce the larval survival and development time of both species, which can potentially impact its distribution and population size.

Performance analysis of a refrigeration system integrated with a thermoelectric cooler and microchannels in terms of heat transfer using a hybrid nanofluid

Advancements in chip technology increase energy consumption due to larger chip capacity, leading to intensive heat flux generation. Cooling solutions, including fan-only, fan-conventional heat sink (HS), or fan-conventional HS-heat pipe (HP) integrated systems, face penalties such as noise, dust accumulation, high electricity usage, space constraints, and thermal limitations of the working fluid. While thermoelectric coolers (TEC) have advantages like compactness and noise-free operation, they alone are insufficient for cooling sophisticated chips; combining them with microchannel heat sinks (MCHS) and superior fluid is crucial for achieving faster and more efficient cooling. Considering previous studies involving TECs used alone, with conventional fluids integrated into MCHS, and with a mono-nanofluid integrated into MCHSs, this is the first study to consider a TEC integrated with two MCHSs and to use a ZnO-TiO2/water hybrid nanofluid to maximize the performance of this miniature refrigeration system. Accordingly, an experimental study was carried out on the aforementioned refrigeration system using various concentrations (φ) of ZnO-TiO2/water hybrid nanofluid for different flow rates, utilizing both conventional heat transfer and the TEC’s mathematical operating principle. The results were interpreted via Reynolds number, Prandtl number, heat transfer rate, Nusselt number, total thermal resistance, and coefficient of performance (COP). The increase in φ from 0% to 0.03%, accompanied by a decrease in flow rate from 16 × 10−5 m3/s to 9 × 10−5 m3/s, increased the heat transfer rate for the heat-absorbing and the heat-emitting sides of the refrigeration system from 19.510 W to 45.794 W, and 13.639 W to 22.406 W, respectively. The experimental COP for pure water was 0.325 at the lowest volume flow rate, but increased to 0.934 at a φ of 0.030%. Considering the thermal characteristics, this study demonstrates that the proposed system is particularly advantageous at low flow rates and high φ, making it a potential candidate for electronic circuit cooling. Considerations such as investigating certain material properties to allow for further improvement of the proposed system were offered.

Acclimation to warming but not hypoxia alters thermal tolerance and metabolic sensitivity in an estuarine crustacean

Coastal species are challenged by multiple anthropogenic stressors. Plasticity may buffer the effects of environmental change, but investigation has largely been restricted to single-stressor performance. Multistressor studies have often been short-term and relatively less is known about the consequences of plasticity under one stressor for performance under another. Here, we aimed to test for the effects of thermal or hypoxic acclimation on thermal tolerance in the amphipod Gammarus chevreuxi. Animals were chronically exposed to raised temperature or hypoxia prior to determination of upper thermal limits and routine metabolic rate (RMR). Warm acclimation increased all metrics of thermal tolerance, but hypoxic acclimation had no effect. Different responses to the two stressors was also observed for the thermal sensitivity of RMR. Consequently, this species possesses the ability to increase thermal tolerance via plasticity in response to chronic warming but increasing duration of hypoxic episodes will not confer cross-tolerance to a warming environment.

Efficacy and Safety of Local Liver Radioablation in Hepatocellular Carcinoma Lesions within and beyond Limits of Thermal Ablation

Introduction: CT-guided interstitial brachytherapy (iBT) radiotherapy has been established in the treatment of liver tumors. With iBT, hepatocellular carcinoma (HCC) lesions can be treated beyond the limits of thermal ablation (i.e., size and location). However, a comprehensive analysis of the efficacy of iBT in patients within and beyond thermal ablation limits is lacking. Materials and Methods: A total of 146 patients with 216 HCC lesions have been analyzed retrospectively. Clinical and imaging follow-up data has been collected. Lesions were evaluated in terms of suitability for thermal ablation or not. The correlation between local tumor control (LTC), time to progression (TTP), overall survival (OS), and clinical and imaging parameters have been evaluated using univariable and multivariable Cox regression analyses. Results: LTC rates at 12 months, 24 months, and 36 months were 87%, 75%, and 73%, respectively. 65% of lesions (n = 141) were not suitable for radiofrequency ablation (RFA). The median TTP was 13 months, and the median OS was not reached (3-year OS rate: 70%). No significant difference in LTC, TTP, or OS regarding RFA suitability existed. However, in the overall multivariable analysis, lesion diameter >5 cm was significantly associated with lower LTC (HR: 3.65, CI [1.60–8.31], p = 0.002) and shorter TTP (HR: 2.08, CI [1.17–3.70], p = 0.013). Advanced BCLC stage, Child-Pugh Stage, and Hepatitis B were associated with shorter OS. Conclusion: iBT offers excellent LTC rates and OS in local HCC treatment regardless of the limits of thermal ablation, suggesting further evidence of its alternative role to thermal ablation in patients with early-stage HCC.

Monolithic three-dimensional tier-by-tier integration via van der Waals lamination.

Two-dimensional (2D) semiconductors have shown great potential for monolithic three-dimensional (M3D) integration due to their dangling-bonds-free surface and the ability to integrate to various substrates without the conventional constraint of lattice matching1-10. However, with atomically thin body thickness, 2D semiconductors are not compatible with various high-energy processes in microelectronics11-13, where the M3D integration of multiple 2D circuit tiers is challenging. Here we report an alternative low-temperature M3D integration approach by van der Waals (vdW) lamination of entire prefabricated circuit tiers, where the processing temperature is controlled to 120 °C. By further repeating the vdW lamination process tier by tier, an M3D integrated system is achieved with 10 circuit tiers in the vertical direction, overcoming previous thermal budget limitations. Detailed electrical characterization demonstrates the bottom 2D transistor is not impacted after repetitively laminating vdW circuit tiers on top. Furthermore, by vertically connecting devices within different tiers through vdW inter-tier vias, various logic and heterogeneous structures are realized with desired system functions. Our demonstration provides a low-temperature route towards fabricating M3D circuits with increased numbers of tiers.

Acclimation to moderate temperatures can have strong negative impacts on heat tolerance of arctic arthropods

Abstract The Arctic is impacted by some of the fastest temperature changes observed on Earth, but the impact on the terrestrial arthropod fauna is unclear. Acute physiological thermal limits of terrestrial ectotherms from high latitudes often exceed the local air temperatures, suggesting that they may be able to cope with increasing temperatures. However, knowledge on how Arctic terrestrial arthropods cope with elevated temperatures for longer periods is lacking. Here we investigate how acclimation temperature and exposure time affect the acute physiological heat tolerance of five terrestrial arthropod species (Neomolgus littoralis, Megaphorura arctica, Nysius groenlandicus, Psammotettix lividellus and Nabis flavomarginatus) immediately after collection in Arctic and sub‐Arctic habitats. We show that although acute heat tolerances are relatively high, even exposure to moderate (temperature span assessed ca. 3–29°C) acclimation temperatures for a 24 h period have strong negative effects on heat tolerance for four of the five species. Similarly, exposure time negatively affected heat tolerance, but depending on species and temperature. Together our results suggest that exposure to even moderately elevated temperatures for periods of 24 h or even shorter can lead to lower acute heat tolerance for cold adapted terrestrial arthropod species from sub‐Arctic and Arctic regions. Consequently, climate change leading to extended periods of mildly elevated temperatures may have strong negative effects on these species. We argue that this aspect is currently overlooked when assessing the ability of arthropods from Arctic and sub‐Artic regions to cope with climate changes as such predictions are typically based on acute heat tolerance estimates and with the assumption of beneficial acclimation responses. Read the free Plain Language Summary for this article on the Journal blog.

Acclimation to higher temperature and antioxidant supplemented diets improved rainbow trout (Oncorhynchus mykiss) resilience to heatwaves

Coldwater species are challenged with increasing water temperatures and fluctuations over their upper thermal limits. This study evaluated the potential of acclimation to higher temperature and dietary antioxidants capacity to mitigate the adverse effects of heat shocks in rainbow trout. To this end, rainbow trout fingerlings were acclimated at optimal (14 °C) and high (20 °C) temperatures and fed on selenium (5 mg/kg) and polyphenol (2 g/kg) supplemented diets for 60 days and then were exposed to heat shocks by increasing water temperature up to 30 °C. Growth performance, survival rate, haemato-immunological parameters, and expression of HSP70α, HSP70β, HSP90β, and IL-1β genes were measured to evaluate the hypothesises. The rainbow trout acclimated to 20 °C and fed on antioxidants supplemented diets showed a significantly higher aftershock survival rate. Moreover, fish acclimated to higher temperature showed higher red blood cell counts as well as serum total protein and albumin during the acclimation trial and heat shocks phase. Acclimation to higher temperature and feeding on antioxidants remarkably enhanced fish immune and antioxidant capacity in comparison to fish adapted to cold water and fed on the basal diet measured by improved respiratory burst and lysozyme activities and upregulation of IL-1β expression during exposure of fish to heat shocks. Furthermore, fish acclimated to higher temperature, especially those fed on antioxidant supplemented diets, showed lower expression levels of HSPs genes during the heat shock phase, indicating that high heat shocks were less stressful for these fish in comparison to cold water acclimated fish. This finding was also supported by lower cortisol levels during heat shocks in fish acclimated to higher temperature. In conclusion, the results of this study indicated that acclimation to higher temperature and/or fed on diets supplemented by selenium and polyphenol, can help to mitigate the adverse effects of the heat shock in rainbow trout.