Temperature Cycling Research Articles

Ultralow Thermal Conductivity and Very High Seebeck Coefficient in Two-Dimensional TeSe2 Semiconductor.

Emerging chalcogenide-based two-dimensional (2D) materials possess various unique yet fully explored properties and are thus considered promising candidates for next-generation optoelectronic and energy conversion applications. Here, TeSe2 crystals with interesting thermoelectric features were synthesized using a simple solid-state reaction. High-resolution transmission electron microscopy reveals that TeSe2 stabilizes in a 2D atomic structure with helical chains, resembling 2D tellurene. The thermoelectric properties were measured from 2 to 390 K in a polycrystalline pellet, showing an ultralow thermal conductivity below 0.25 W m-1 K-1 and a very high positive Seebeck coefficient of up to 865 μV K-1. Particularly, the thermal conductivity shows a hysteresis effect upon temperature cycling, which is tentatively explained as cracks opening and partially closing. Optical measurements indicate that TeSe2 is a semiconductor with two bandgaps at 1.43 and 1.65 eV. These results highlight that TeSe2 is an intriguing 2D semiconductor with complex thermoelectric properties, which provides a platform to further study the interplay of emerging 2D structure, thermal, and electronic properties.

Rigid polyurethane foam with durable hydrophobicity and flame retardancy endowed by novel functional surfactants

Traditional rigid polyurethane foam (RPUF) with flame retardancy might be easily damaged in some moist condition due to its hydrophobicity, which would lead to unsafety. Therefore, novel surfactants with both hydrophobic fluorinated group and flame-retardant phosphorus group were synthesized. With lower surface tension and more hydrogen bonds formed in polyurethane, the mixed surfactants, which were used in the preparation of RPUF, have not only obviously improved the size uniformity and integrity of cells but also enhanced its hydrophobicity, compressive strength and thermal insulating performance. Besides, effective ‘protection’ could be constructed on the surface of RPUF by prepared surfactants, when ammonium polyphosphate (APP) and expandable graphite (EG) were introduced to provide good flame retardancy. As a result, with just 2.8wt% content of those functional surfactants, hydrophobic and flame-retardant RPUF with water contact angle of 126 °, limiting oxygen index of 25%, compressive strength of 1.3MPa and thermal conductivity of 27mW/mK, were finally obtained, which is ahead of other flame-retardant RPUF reported before. It’s worth noting that, this hydrophobic and flame-retardant RPUF exhibits more stable and durable properties when soaking in HCl solution (2mol/L), NaOH solution (2mol/L), NaCl saturated solution and various solvents (THF and EtOH), or under strong fiction for 100 times and high and low temperature cycling test for 20 times. This would provide a novel and effective strategy to endow RPUF with enhanced and durable flame retardancy, hydrophobicity, compressive strength and thermal insulating performance even under extreme conditions.

Effects of urban areas on the diurnal cycle of temperature and precipitation in a global climate simulation

AbstractAnalyses of global climate model results for urban impacts on temperature and precipitation are rare. Previous analyses of the global Conformal Cubic Atmospheric Model simulation results for 1985–2010 have revealed urban effects on minimum and maximum temperatures. Using the same dataset to derive time‐zone‐corrected three‐hourly local time period (LTP) data, averaged diurnal cycles of temperature and precipitation were calculated for grid cells with greater than 10% urban fraction (urban grid cells) globally. Three latitudinal bands were assessed: northern extratropics (NET, 274 urban grid cells), southern extratropics (SET, 39 urban grid cells), and the Tropics (26 urban grid cells). The largest statistically significant urban influences on temperature are consistently found at night, in agreement with many previous studies on urban heat islands. Signs of urban cooling were found for a few hours, from 09:00 to 15:00 LTP, most often in summer. Influences of urban areas on precipitation varied, with small increases and decreases in all latitudinal bands and seasons. For NET, increases were generally found. In the Tropics, increases were found from 21:00 to 09:00 LTP for all seasons except DJF, with decreases for all seasons from 15:00 to 18:00 LTP. In SET, all seasons had increases for 21:00 to 00:00 LTP and decreases for 15:00 to 18:00 LTP. DJF had decreases for all LTPs except 21:00 to 00:00 LTP and SON had increases for all times except 15:00 to 18:00 LTP. Differences in rainfall in the region surrounding the urban areas were broadly similar to local changes in NET. For the Tropics and SET, regional decreases were found for DJF and JJA, with a more varied pattern for other months. Regional effects appeared to be more restricted to near‐urban areas in the Tropics than in NET. The results indicate some influence of nearby urban areas on regional temperature and precipitation.

Calibration of Heat Source Models in Numerical Simulations of Welding Processes

This article presents issues related to the methodology of the correct definition of the heat source model in the numerical analyses of welding processes. The problem of determining the input data for the stage of a heat source model definition, obtaining input data from experiments, and their proper interpretation and use in defining the numerical model was discussed. Particular attention is paid to the specificity of the problem of defining the heat source model, the way of interpreting the results of the analyses and the way of comparing them with the results of real experiments. The basic problems related to the mapping of the complex geometry of the molten metal pool and the ways to solve them were indicated. The solutions and guidelines presented in the article allow to improve the accuracy and quality of the obtained results of numerical analyses, as well as to shorten the time of preparation of computational models by reducing the number of computational iterations related to the search for the maximum consistency of the compared values and temperature cycles.

Finite element simulation investigation of warping deformation during baking temperature cycle of dissimilar materials sandwich adhesive bonded structures of car body

Adhesive bonding is crucial for joining lightweight, mixed-material car bodies but can cause distortion due to changes in adhesive properties during heat curing. In this paper, based on the characteristics of the roller-hemming structures, a sandwich adhesive bonded structure of aluminum-steel dissimilar materials was designed. A viscoelastic model for the hemming adhesive was developed, and a coupled thermal-chemical-structural model was implemented in ABAQUS. Baking experiments validated the model. Stress and strain variations were analyzed to understand warping mechanisms during the temperature cycle. Further analysis results showed that decreasing heating rate, holding temperature, or increasing cooling rate can reduce deformation.

Regulation of Crystal Habit via Coupling “Growth Dead Zone” and Temperature Cycling Strategy: Modeling and Validation

Regulation of Crystal Habit via Coupling “Growth Dead Zone” and Temperature Cycling Strategy: Modeling and Validation

Assessing the viability of using ground-air heat exchangers during winter months in different climatic conditions of Iran

ABSTRACT Ground combined with subsurface tubes as heat exchangers, known as Ground-Air Heat Exchangers (GAHEs), have recently gained attention for heating and cooling. However, several simplifications were used to capture complex airflow characteristics in previous studies which potentiate inaccuracy in their results. This gap is addressed in this study by developing a 3D transient model incorporating realistic heat dynamics and turbulent airflow simulation using the k-epsilon model over a complete temperature cycle. The experimental result serves to corroborate the model’s accuracy. Further, the model is utilised to assess energy-conversion potential of GAHEs for heating a generic building during January in four Iranian cities with different climates. Findings show distinct differences between the GAHE’s energy-conservation capacity in these cities. The GAHE can conserve up to 714.6 kWh of energy monthly in the coldest climate and reduce peak heating loads by up to 36.0% in the hottest climate, with these averages observed across all soil types. GAHE energy saving is increased up to 27.7% when the soil around it is silt with a higher conductivity. Additionally, an adverse impact on building’s heating is created by the GAHE in some cases, highlighting the significance of hourly management of the system. Highlights A 3D transient numerical scheme was created based on fluid mechanics principles to simulate a multitube GAHE, and the solution was verified using empirical data. The effectiveness of the GAHE and its ability to reduce the maximum heating demand of a particular building for different climates within Iran in January were examined. The impact of soil characteristics on the energy-saving capability of the GAHE was found to be significant in the four cities under study, and a distinct difference in heat flux to the working fluid was discovered in different climates.

Addressing challenges for operating electrochemical solar fuels technologies under variable and diurnal conditions

The outdoor operation of electrochemical solar fuels devices must contend with challenges presented by the cycles of solar irradiance, temperature, and other meteorological factors. Herein, we discuss challenges associated with these fluctuations presented over three timescales, including the effects of diurnal cycling over the course of many days, a single diurnal cycle over the course of hours, and meteorological phenomena that cause fluctuations on the order of seconds to minutes. We also highlight both reaction-independent and reaction-specific effects of variable conditions for the hydrogen evolution reaction and CO2 reduction reaction. We identify key areas of research for advancing the outdoor operation of solar fuels technology and highlight the need for metrics and benchmarks to enable the comparison of diurnal studies across systems and geographical locations.

Hispolon-loaded lipid nanocapsules for the management of hepatocellular carcinoma: comparative study with solid lipid nanoparticles and suspension.

Aim: The present study aims to develop, optimize and assess hispolon (HPN) lipid nanocapsules (LNCs), solid lipid nanoparticles (SLNs) and suspension for treating hepatocellular carcinoma (HCC).Materials & methods: It included UPLC-MS/MS, solubility, optimization, characterization, stability, in vitro and in vivo studies.Results: HPN-loaded LNCs were developed using phase-inversion and temperature cycling, while SLNs and suspension using hot homogenization and trituration methods. HPN-LNCs had a particle size (PS) of 196.9nm, a PDI of 0.315 and a zeta potential of -24.3mV. HPN-S2 had a PS of 199.90nm, a PDI of 0.381 and a zeta potential of -19.1mV. HPN-SPN3 showed a PS of 946.60nm, a PDI of 0.31 and a zeta potential of -0.1945mV. Stability tests over 3 months and gastric stability testing in different media showed no significant changes in PS, PDI, entrapment efficiency (EE) and loading capacity (LC). HPN-LNCs demonstrated 96.22% sustained drug release over 25h, outperforming HPN-S2 (87.12%) and HPN-SPN3 (22% within 2h). HPN-loaded LNCs improved oral bioavailability by 2.03-times, the most effective hepatoprotective action and higher localization in liver tumors over HPN-S2 and HPN-SPN3.Conclusion: HPN-Loaded LNCs results are promising, but more safety data needed in the future.

Strain Measurement on a PBX during Temperature Cycling Using Fibre Bragg Gauges

AbstractThe anisotropic and irreversible expansion properties of polymer‐bonded explosives (PBX) can significantly influence the utility and reliability of associated equipment. The physical state of PBX under temperature cycling affects the strain distribution across the surface of cylindrical specimens. This strain is indicative of the irreversible growth and anisotropic expansion of the specimens. In this study, fiber Bragg grating sensors are employed to monitor the strain of PBX throughout the temperature cycling process, and our focus was on analyzing the changes in anisotropy and strain distribution during the cycle. The relationships between strain, temperature, material properties, and differences among various materials are examined. Experimental results indicate that the strain along the height and radial directions of the PBX specimens displayed a monotonic gradient distribution, increasing progressively in areas of higher density. TATB‐based PBX exhibited anisotropic expansion throughout the temperature cycling, with the degree of anisotropy increasing during heating and decreasing upon cooling. Conversely, HMX‐based PBX showed greater expansion in the height direction during both the heating and cooling phases, but it did not display noticeable anisotropy following the temperature cycling. At the highest temperature‐holding stage (100°C), the HMX‐based PBX was isotropic. The extent of strain in PBX was correlated with the thermal expansion coefficient of the crystal, although the final degree of expansion was not dependent on the initial range of strain. The ratchet growth of TATB‐based PBX was approximately 31 μϵ greater than that of HMX‐based PBX.

A Combined Experimental and Computational Study on the Effect of the Reactor Configuration and Operational Procedures on the Formation, Growth and Dissociation of Carbon Dioxide Hydrate

Clathrate hydrate-based technologies are considered promising and sustainable alternatives for the effective management of the climate change risks related to emissions of carbon dioxide produced by human activities. This work presents a combined experimental and computational investigation of the effects of the operational procedures and characteristics of the experimental configuration, on the phase diagrams of CO2-H2O systems and CO2 hydrates’ formation, growth and dissociation conditions. The operational modes involved (i) the incremental (step-wise) temperature cycling and (ii) the continuous temperature cycling processes, in the framework of an isochoric pressure search method. Also, two different high-pressure PVT configurations were used, of which one encompassed a stirred tank reactor and the other incorporated an autoclave of constant volume with magnetic agitation. The experimental results implied a dependence of the subcooling degree, (P, T) conditions for hydrate formation and dissociation, and thermal stability of the hydrate phase on the applied temperature cycling mode and the technical features of the utilized PVT configuration. The experimental findings were complemented by a thermodynamic simulation model and other calculation approaches, with the aim to resolve the phase diagrams including the CO2 dissolution over the entire range of the applied (P, T) conditions.

The effects of specimens geometry on solidification conditions and microstructure formation in laser powder bed fusion fabricated Ti–6Al–4V alloys

Laser powder bed fusion (LPBF) excels at creating intricately shaped parts, which will result in variations in solidification conditions, microstructure formation and mechanical properties. To address this issue, three distinct shapes: cubic, pyramidal and inversed pyramidal Ti–6Al–4V alloy specimens were fabricated using LPBF technology. The effects of specimen geometry on microstructure formation, transformation as well as its effects on mechanical properties were investigated in the present study. Our results show that specimen geometry significantly affects the thermal gradient, influencing nucleation and growth during fabrication. EBSD (Electron Backscatter Diffraction) characterization reveals that the primary β-phase grows in columnar grains in cubic specimens, coarse columnar grains along lateral faces in pyramidal specimens, and nearly equiaxed grains in inverted pyramidal specimens, leading to a significant reduction in texture. Nanoindentation tests show higher nanohardness in the top parts of cubic and pyramidal specimens compared to the bottom parts, while inverted pyramidal specimens have consistent nanohardness throughout. This variation is due to differences in solid solute concentration, melt pool undercooling, and thermal histories during and post solidification processes respectively. TEM results indicate that the fine lath phase on the top parts has transformed into β-phase, while the bottom parts remain as α′ phase, highlighting a disparity due to different thermal cycling times and temperatures.

Fundamental and Practical Aspects of Break-In/Conditioning of Proton Exchange Membrane Fuel Cells.

Proton exchange membrane fuel cells (PEMFCs) have proven to be a promising power source for various applications ranging from portable devices to automotive and stationary power systems. The production of PEMFC involves numerous stages in the value chain, with each stage presenting unique challenges and opportunities to improve the overall performance and durability of the PEMFC stack. These include steps such as manufacturing the key components such as the platinum-based catalyst, processing these components into the membrane electrode assemblies (MEAs), and stacking the MEAs to ultimately produce a PEMFC stack. However, it is also known that the break-in or conditioning phase of the stack plays a crucial role in the final performance as well as durability. It involves several key phenomena such as hydration of the membrane, swelling of the ionomer, redistribution of the catalyst and the creation of suitable electrochemical interfaces - establishment of the triple phase boundary. These improve the proton conductivity, the mass transport of reactants and products, the catalytic activity of the electrode and thus the overall efficiency of the FC. The cruciality of break-in is demonstrated by the improvement in performance, which can even be over 50 % compared to the initial state. The state-of-the-art approach for the break-in of MEAs involves an electrochemical protocol, such as voltage cycling, using a PEMFC testing station. This method is time-consuming, equipment-intensive, and costly. Therefore, new, elegant, and cost-effective solutions are needed. Nevertheless, the primary aim is to achieve maximum/optimal performance so that it is fully operational and ready for the market. It is therefore essential to better understand and deconvolute these complex mechanisms taking place during break-in/conditioning. Strategies include controlled humidity and temperature cycling, novel electrode materials and other advanced break-in methods such as air braking, vacuum activation or steaming. In addition, it is critical to address the challenges associated with standardisation and quantification of protocols to enable interlaboratory comparisons to further advance the field.

The Reindeer Circadian Clock Is Rhythmic and Temperature-compensated But Shows Evidence of Weak Coupling Between the Secondary and Core Molecular Clock Loops.

Circadian rhythms synchronize the internal physiology of animals allowing them to anticipate daily changes in their environment. Arctic habitats may diminish the selective advantages of circadian rhythmicity by relaxing daily rhythmic environmental constraints, presenting a valuable opportunity to study the evolution of circadian rhythms. In reindeer, circadian control of locomotor activity and melatonin release is weak or absent, and the molecular clockwork is reportedly non-functional. Here we present new evidence that the circadian clock in cultured reindeer fibroblasts is rhythmic and temperature-compensated. Compared with mouse fibroblasts, however, reindeer fibroblasts have a short free-running period, and temperature cycles have an atypical impact on clock gene regulation. In reindeer cells, Per2 and Bmal1 reporters show rapid responses to temperature cycles, with a disintegration of their normal antiphasic relationship. The antiphasic Per2-Bmal1 relationship re-emerges immediately after release from temperature cycles, but without complete temperature entrainment and with a marked decline in circadian amplitude. Experiments using Bmal1 promoter reporters with mutated RORE sites showed that a reindeer-like response to temperature cycles can be mimicked in mouse or human cell lines by decoupling Bmal1 reporter activity from ROR/REV-ERB-dependent transcriptional regulation. We suggest that weak coupling between core and secondary circadian feedback loops accounts for the observed behavior of reindeer fibroblasts in vitro. Our findings highlight diversity in how the thermal environment affects the temporal organization of mammals living under different thermoenergetic constraints.

Satellite-based estimation of monthly mean hourly 1-km urban air temperature using a diurnal temperature cycle model

Cities worldwide face escalating climate change risks, underscoring the need for spatially and temporally resolved urban air temperature (Ta) data. While satellite-derived land surface temperature (LST) data have been widely used to estimate Ta, high-resolution hourly Ta estimation in urban areas remains underexplored. Traditional methods typically rely on LST data from geostationary satellites and continuous 24-h Ta observations from weather stations. To address these limitations, we introduce a method that combines a diurnal temperature cycle (DTC) model with a random forest model to estimate monthly mean hourly urban Ta at 1-km resolution. This approach leverages a limited number of diurnal Ta observations from weather stations, MODIS LST data, and ancillary information. The core idea of the proposed method is to transform the estimation of monthly mean hourly 1-km Ta into estimating 1-km DTC model parameters, primarily daily maximum and minimum Ta values. This method capitalizes on MODIS LST's ability to estimate daily Ta extremes and requires only four diurnal Ta observations within a daily cycle to estimate monthly mean hourly 1-km Ta. Station-based five-fold cross-validation yields overall RMSE values consistently below 1.0 °C across nine cities with diverse geographic and climatic contexts. The accuracy achieved with only four diurnal Ta observations rivals that obtained using continuous 24-h Ta observations. Even with a limited training set of ten stations, the overall RMSE remains below 1.0 °C for most cities. The proposed method proves effective for both single-city and multi-city modeling and can estimate daily hourly 1-km Ta under clear-sky conditions. In conclusion, this study offers a feasible, efficient, and versatile method for accurately estimating monthly mean hourly 1-km Ta, which can be readily applied to other cities and holds potential for various applications.

A-271 Expansion of sample viability for self-collected urine specimens containing CT/NG & TV/MG utilizing the Roche cobas® 6800 System

Abstract Background The CDC estimates that 1 in 5 Americans have an STI. Home collection for STIs could help mitigate the stigma, cost, and accessibility, which contribute to low diagnosis rates and disparities in diagnosis and treatment. Home self-collected specimens occasionally arrive in the lab with volumes higher or lower than what is required by the assay manufacturer’s specifications for self-collection. This study demonstrates that sample stability is retained after temperature fluctuation via shipping - even when the correct ratio of buffer to sample has been disturbed, a precise and accurate measurement persists. Our goal is to improve accessibility to discreet, patient collected STI tests. Methods Positive samples were prepared by spiking negative urine with organisms near the manufacturer’s limit of detection (LoD). Properly collected samples were aliquoted into tubes with 5mL volumes as per manufacturer specifications. Improperly collected samples were either overfilled (9mL for CT/NG, 7mL for TV/MG) or underfilled (1mL for CT/NG, 2mL for TV/MG). Samples underwent temperature cycling to mimic summer or winter shipping conditions. Ambient temperature studies were conducted on over/underfilled specimens. All samples were baseline tested and compared qualitatively to the manufacturer's claimed LoD using the Roche c6800 and the IVD assays for CT/NG & TV/MG. Results Improperly filled samples were stable at ambient temperature for 63 days for CT/NG, and 59 days for TV/MG. See chart for temperature cycling results. All samples (n=164) showed 100% qualitative agreement with their baseline result after summer and winter shipping challenges. Conclusions Urine samples that fail to satisfy the manufacturer’s self-collection specifications or have endured temperature fluctuations still yield accurate CT/NG & TV/MG results. These results indicate the potential to enhance sample viability and patient accessibility utilizing validated IVD assays.

Trends and cycles in rainfall, temperature, NDVI, IOD and SOI in the Mara-Serengeti: Insights for biodiversity conservation

Trends and cycles in rainfall, temperature, NDVI, IOD and SOI in the Mara-Serengeti: Insights for biodiversity conservation

The Streamflow Response to Multi‐Day Warm Anomaly Events: Sensitivity to Future Warming and Spatiotemporal Variability by Event Magnitude

AbstractPersistent warm temperature anomalies can drive streamflow in regions where snow and glacier melt are important constituents of streamflow. However, the spatiotemporal variability of the streamflow response depends on both the magnitude of the forcing temperature anomalies and the nature of the underlying hydrological system. Here we ask: when, where, and for what magnitude of temperature anomalies will the streamflow response change most rapidly under warming? We use observed streamflow and temperature for 868 basins across Canada to quantify the streamflow response during warm temperature anomalies and how such responses vary in space, time, and by anomaly magnitude. We first identify two temporal modes of the streamflow response, one in autumn and one in spring, the relative strength of which varies by climate. We then use sinusoidal approximations of seasonal temperature cycles to characterize the sensitivity of such modes to changes in annual temperature. At individual basins, we find that relative to moderate warm events, the streamflow response to more extreme warm events is more sensitive to changes in mean annual temperatures, and this sensitivity is greatest in the coastal, southern, and central regions of Canada. Our results have implications for how the hydrological impacts of extreme events, such as heatwaves, will change in space and time under future climate change.

Increased offspring size and reduced gestation length in an ectothermic vertebrate under a worst-case climate change scenario

As global temperatures continue to rise, understanding the impacts of warming environments has become increasingly important. Temperature is especially relevant for ectothermic organisms which depend upon consistent and predictable annual temperature cycles for reproduction and development. However, additional research is required in this area to elucidate the potential impacts of climate change on future generations. To understand how projected increases in environmental temperatures may impact reproductive outcomes within natural populations of ectothermic vertebrates, we manipulated minimum ambient temperatures during gestation in Red-sided garter snakes (Thamnophis sirtalis parietalis). Wild snakes were collected in the Interlake region of Manitoba, Canada during their spring mating season and allowed to mate in controlled conditions. For the duration of gestation, mated females were placed into one of two ambient thermal conditions: temperatures emulating those found in the species’ natural habitat or temperatures with a consistent 5 °C increase to match end-of-century climate change projections. We recorded observations for each litter and all neonates resulting from controlled mating trials. We observed no difference in litter sizes or birth rates between thermal conditions. However, we observed a significant reduction in gestation length and significant increase to neonate body mass and body condition associated with increased ambient temperatures. These results suggest that increased minimum temperatures during gestation may confer reproductive benefits for the northern populations of this species even under the most extreme current modeled warming predictions. We discuss the broader implications of this effect, including possible negative ecological outcomes.

Analysis of High and Low Temperature Performance of Titanium Zirconium Molybdenum Alloy and High Temperature Alloy Brazed Joint

Abstract Using niobium as the intermediate layer and gold nickel (Au82-Ni) filler metal, TZM alloy and high-temperature alloy GH3128 were brazed. The brazed specimens were subjected to 400 cycles of high and low temperature cycling tests at temperatures ranging from 650 °C ∼ 680 °C (high temperature) to -196 °C (low temperature) for 10 minutes seperately. Then the microstructure variation before and after the experiment were observed and the shear strength of the specimens were tested at room temperature for 50 cycles of 400 high and low temperature testing.. The results show that the microstructure of the transition zone at the brazing interface after brazing is uniform and dense, with good wettability with the substrate and no defects such as cracks. The solder and substrate undergo diffusion reactions, and the molybdenum alloy, niobium, and niobium, high-temperature alloy had each form diffusion layers, formed intermetallic compounds on the brazing surface. After high and low temperature cycling, cracks exist in the braze seam between molybdenum alloy and niobium alloy. The cracking mode should be thermal fatigue based on the fracture morphology and phase analysis. The reasons of interface cracking are that due to different thermal expansion coefficients, low mutual solid solubility, and the formation of a large number of different types of intermetallic compounds, Mo and Nb materials have poor brazing compatibility and lower interface strength. Under cold and hot cycling conditions, brittle intermetallic compounds are prone to form crack source areas. As the number of cycles increases, the cracks gradually expand, ultimately leading to product leakage. In addition, the shear strength of brazed joints shows a decreasing trend with the increase of high and low temperature cycles in 400 high and low temperature tests.