Difference In Temperature Dependence Research Articles

Factors influencing the in situ formation of Δ9-THC from cannabidiol during GC-MS analysis.

Gas chromatography-mass spectrometry (GC-MS) is widely used for the identification of cannabinoids in seized plant material. Conditions used for instrumental analysis should maximize decarboxylation, while minimizing the in situ production of Δ9-THC inside the GC inlet. In this study, decarboxylation of the acidic Δ9-THC precursor and in situ degradation of cannabidiol (CBD) were investigated using seven commercial GC liners with different deactivation chemistries and geometries. While the inlet temperature was previously optimized at 250°C in a previously validated assay, we systematically examined the temperature-dependent decarboxylation of tetrahydrocannabinolic acid-A (Δ9-THCA-A) and cyclization of CBD between 230°C and 310°C using different liners using favorable and unfavorable conditions. Significant differences in decarboxylation rate and CBD cyclization were observed between different liner types. While no temperature-dependent differences in decarboxylation rate were observed within liner type, liner-dependent differences were observed (α =0.05), particularly between those with different geometry. In contrast, temperature and liner-dependent differences were observed for in situ formation of Δ9-THC (α =0.05). This was influenced by liner geometry and to a smaller extent by surface deactivation. Effects were exacerbated with liner usage. While significant differences were observed using new and used GC liners, differences between liners of the same type but different lot numbers were not observed. Inter-instrument differences using the same liner were also evaluated and had minimal effect. Liner- and temperature-dependent effects were also confirmed using more than 20 cannabis plant extracts. Careful selection of liner, inlet conditions, and regular preventive maintenance can mitigate the risks associated with in situ formation Δ9-THC from CBD.

The genome and sex-dependent responses to temperature in the common yellow butterfly, Eurema hecabe

BackgroundLepidoptera (butterflies and moths) is one of the most geographically widespread insect orders in the world, and its species play important and diverse ecological and applied roles. Climate change is one of the biggest challenges to biodiversity this century, and lepidopterans are vulnerable to climate change. Temperature-dependent gene expression differences are of relevance under the ongoing climate crisis. However, little is known about how climate affects gene expression in lepidopterans and the ecological consequences of this, particularly with respect to genes with biased expression in one of the sexes. The common yellow butterfly, Eurema hecabe (Family Pieridae), is one of the most geographically widespread lepidopterans that can be found in Asia, Africa, and Australia. Nevertheless, what temperature-dependent effects there may be and whether the effects differ between the sexes remain largely unexplored.ResultsHere, we generated high-quality genomic resources for E. hecabe along with transcriptomes from eight developmental stages. Male and female butterflies were subjected to varying temperatures to assess sex-specific gene expression responses through mRNA and microRNA transcriptomics. We find that there are more temperature-dependent sex-biased genes in females than males, including genes that are involved in a range of biologically important functions, highlighting potential ecological impacts of increased temperatures. Further, by considering available butterfly data on sex-biased gene expression in a comparative genomic framework, we find that the pattern of sex-biased gene expression identified in E. hecabe is highly species-specific, rather than conserved across butterfly species, suggesting that sex-biased gene expression responses to climate change are complex in butterflies.ConclusionsOur study lays the foundation for further understanding of differential responses to environmental stress in a widespread lepidopteran model and demonstrates the potential complexity of sex-specific responses of lepidopterans to climate change.

Self-driven thermoelectric cooling contraption for liquid metals under the static magnetic field

The presence of large temperature gradients in liquid metals during heat transfer can also induce thermoelectric effects, which can lead to pumping or stirring of liquid metals under the action of magnetic fields. The thermoelectric effect of liquid metals has potential application background in both nuclear fusion and metal metallurgy. In this paper, an experimental study of flow driven by the Seebeck effect, in which the temperature-dependent voltage difference at an interface between dissimilar metals, in the presence of a magnetic field, can be used to create a Lorentz force. It is proposed that this method could be used for cooling electronics, fusion reactors, and solar technologies. The working fluid is eutectic gallium–indium–tin, and flow measurements are made with ultrasound. The flow velocity tends to increase and then decrease as the magnetic field increases. Two scaling relations are developed to predict the velocity, one for weak magnetic fields and one for strong magnetic fields. Those predictions are combined to estimate the maximum velocity. Temperature gradients and wall conductance ratio have a significant effect on the Seebeck effect self-driven flow. It is found that the self-driven flow velocity caused by the Seebeck effect is positively correlated with the number of channels in the multi-channel experiments. This design idea of self-generated flow and heat transfer of liquid metal in the magnetic field will provide the possibility of pumpless self-driven liquid lithium flow in nuclear fusion reactors and provide new ideas for cooling of electronic products and related energy-saving and emission reduction applications.

Influence of spin fluctuations on structural phase transitions of iron

The effect of spin fluctuations on the $\ensuremath{\alpha}$ (bcc)-$\ensuremath{\gamma}$ (fcc)-$\ensuremath{\delta}$ (bcc) structural phase transitions in iron is investigated with a tight-binding (TB) model. The orthogonal $d$-valent TB model is combined with thermodynamic integration, spin-space averaging, and Hamiltonian Monte Carlo to compute the temperature-dependent free-energy difference between bcc and fcc iron. We demonstrate that the TB model captures experimentally observed phonon spectra of bcc iron at elevated temperatures. Our calculations show that spin fluctuations are crucial for both the $\ensuremath{\alpha}\text{\ensuremath{-}}\ensuremath{\gamma}$ and $\ensuremath{\gamma}\text{\ensuremath{-}}\ensuremath{\delta}$ phase transitions but they enter through different mechanisms. Spin fluctuations impact the $\ensuremath{\alpha}\text{\ensuremath{-}}\ensuremath{\gamma}$ phase transition mainly via the magnetic/electronic free-energy difference between bcc and fcc iron. The $\ensuremath{\gamma}\text{\ensuremath{-}}\ensuremath{\delta}$ phase transition, in contrast, is influenced by spin fluctuations only indirectly via the spin-lattice coupling. Combining the two mechanisms, we obtain both the $\ensuremath{\alpha}\text{\ensuremath{-}}\ensuremath{\gamma}$ and $\ensuremath{\gamma}\text{\ensuremath{-}}\ensuremath{\delta}$ phase transitions with our TB model. The calculated transition temperatures are in very good agreement with experimental values.

Ab initio prediction of temperature-dependent stability of heterogeneous B19′ phase in TiNi alloy using atomistically informed Eshelby’s ellipsoidal inclusion

In this study, we energetically predicted the temperature-dependent stability of the heterogeneous B19′ phase in the B2 matrix of TiNi alloys using density functional theory (DFT) and phonon analysis informed Eshelby’s ellipsoidal inclusion. The temperature-dependent eigenstrains and elastic constants for Eshelby’s ellipsoidal inclusion were calculated using DFT and phonon analysis under a quasi-harmonic approximation. The stable orientation of the disk-shaped B19′ phase in the B2 matrix and its total strains were evaluated with respect to temperature using Eshelby’s ellipsoidal inclusion analysis. Using the total strains, the elastically deformed atomic structure of the heterogeneous B19′ phase in the B2 matrix was determined, and its temperature-dependent free energy was calculated using DFT calculations and phonon analysis. Comparing the temperature-dependent free energies of the B2 and elastically deformed B19′ structures, we successfully predicted that the transformation between the two phases occurs at 300 K, which agrees with experimental observations. Moreover, it is shown that the temperature-dependent difference in the elastic constants between the B19′ phase and B2 matrix influences the phase transformation, which is the origin of the shape-memory effect of TiNi alloy.

Room-temperature crystallography reveals altered binding of small-molecule fragments to PTP1B.

Much of our current understanding of how small-molecule ligands interact with proteins stems from X-ray crystal structures determined at cryogenic (cryo) temperature. For proteins alone, room-temperature (RT) crystallography can reveal previously hidden, biologically relevant alternate conformations. However, less is understood about how RT crystallography may impact the conformational landscapes of protein-ligand complexes. Previously, we showed that small-molecule fragments cluster in putative allosteric sites using a cryo crystallographic screen of the therapeutic target PTP1B (Keedy et al., 2018). Here, we have performed two RT crystallographic screens of PTP1B using many of the same fragments, representing the largest RT crystallographic screens of a diverse library of ligands to date, and enabling a direct interrogation of the effect of data collection temperature on protein-ligand interactions. We show that at RT, fewer ligands bind, and often more weakly - but with a variety of temperature-dependent differences, including unique binding poses, changes in solvation, new binding sites, and distinct protein allosteric conformational responses. Overall, this work suggests that the vast body of existing cryo-temperature protein-ligand structures may provide an incomplete picture, and highlights the potential of RT crystallography to help complete this picture by revealing distinct conformational modes of protein-ligand systems. Our results may inspire future use of RT crystallography to interrogate the roles of protein-ligand conformational ensembles in biological function.

Platelet Aggregation, Mitochondrial Function and Morphology in Cold Storage: Impact of Resveratrol and Cytochrome c Supplementation.

Donated platelets are critical components of hemostasis management. Extending platelet storage beyond the recommended guidelines (5 days, 22 °C) is of clinical significance. Platelet coagulation function can be prolonged with resveratrol (Res) or cytochrome c (Cyt c) at 4 °C. We hypothesized that storage under these conditions is associated with maintained aggregation function, decreased reactive oxygen species (ROS) production, increased mitochondrial respiratory function, and preserved morphology. Donated platelets were stored at 22 °C or 4 °C supplemented with 50 μM Res or 100 μM Cyt c and assayed on days 0 (baseline), 5, 7 and 10 for platelet aggregation, morphology, intracellular ROS, and mitochondrial function. Declining platelet function and increased intracellular ROS were maintained by Res and Cyt c. Platelet respiratory control ratio declined during storage using complex I + II (CI + CII) or CIV substrates. No temperature-dependent differences (4 °C versus 22 °C) in respiratory function were observed. Altered platelet morphology was observed after 7 days at 22 °C, effects that were blunted at 4 °C independent of exposure to Res or Cyt c. Storage of platelets at 4 °C with Res and Cyt c modulates ROS generation and platelet structural integrity.

Dual effect of metals on branchial and renal Na,K-ATPase activity in thermally acclimated crucian carp (Carassius carassius) and rainbow trout (Oncorhynchus mykiss)

Heavy metals are harmful to aquatic animals by disrupting their ionic balance. Here, we compare the effects of three metals, zinc (Zn), nickel (Ni) and manganese (Mn) on Na,K-ATPase activity in gills and kidneys in fish species with different ecophysiological characteristics. Crucian carp (Carassius carassius), a cold-dormant species, and rainbow trout (Oncorhynchus mykiss), a cold-active species, were acclimated to 2 °C and 18 °C, and branchial and renal Na,K-ATPase activities were measure in the presence of Zn, Ni and Mn. Under basal conditions, species-, tissues- and temperature-dependent differences appeared in Na,K-ATPase activity. Renal Na,K-ATPase activity was higher in trout than carp, and cold-acclimation increased Na,K-ATPase activity in both species. Cold-acclimation reduced branchial Na,K-ATPase activity in carp, but no acclimation effect was found in trout. In both species and tissues, Zn stimulated Na,K-ATPase in concentration-dependent manner at 0.1 to 3 μM. At 30 µM, Zn strongly inhibited both branchial and renal Na,K-ATPase in both species. Inhibition by Zn was stronger in trout than carp, but no differences existed between acclimation groups in either species. Ni (0.1–3.0 µM) stimulated renal Na,K-ATPase in crucian carp but not in rainbow trout. At 30 µM, Ni depressed the renal Na,K-ATPase of carp back to the control level. Mn had no statistically significant effect on Na,K-ATPase in either species. At low concentrations, Zn and Ni impose an energetic cost to fish by increasing ATP consumption in Na,K-ATPase activity. At higher concentrations, Zn, but not Ni and Mn, strongly inhibit renal and branchial Na,K-ATPase. Due to differences in baseline activity level and acclimation-induced changes in renal and branchial Na,K-ATPase, metal pollution may impair ion regulation of fish in species-specific manner and depending on season.

Temperature-dependent Small RNA Expression Depends on Wild Genetic Backgrounds of Caenorhabditis briggsae.

Geographically distinct populations can adapt to the temperature conditions of their local environment, leading to temperature-dependent fitness differences between populations. Consistent with local adaptation, phylogeographically distinct Caenorhabditis briggsae nematodes show distinct fitness responses to temperature. The genetic mechanisms underlying local adaptation, however, remain unresolved. To investigate the potential role of small noncoding RNAs in genotype-specific responses to temperature, we quantified small RNA expression using high-throughput sequencing of C. briggsae nematodes from tropical and temperate strain genotypes reared under three temperature conditions (14 °C, 20 °C, and 30 C). Strains representing both tropical and temperate regions showed significantly lower expression of PIWI-interacting RNAs (piRNAs) at high temperatures, primarily mapping to a large ∼7 Mb long piRNA cluster on chromosome IV. We also documented decreased expression of 22G-RNAs antisense to protein-coding genes and other genomic features at high rearing temperatures for the thermally-intolerant temperate strain genotype, but not for the tropical strain genotype. Reduced 22G-RNA expression was widespread along chromosomes and among feature types, indicative of a genome-wide response. Targets of the EGO-1/CSR-1 22G-RNA pathway were most strongly impacted compared with other 22G-RNA pathways, implicating the CSR-1 Argonaute and its RNA-dependent RNA polymerase EGO-1 in the genotype-dependent modulation of C. briggsae 22G-RNAs under chronic thermal stress. Our work suggests that gene regulation via small RNAs may be an important contributor to the evolution of local adaptations.

Cost and time effective performance evaluation methods for photovoltaic module cooling techniques: Analytical and experimental study

For assessing the performance of a photovoltaic module (PV) cooler, the temperature-dependent PV efficiency difference factor, FTDED, was introduced earlier. The assessment was accomplished by differentiating whether the PV cooler performance was contributing to the gain or loss to the PV efficiency. That method is costly because it requires the availability of a fixed amount of solar irradiance of 1000 W/m2 that satisfy the PV standard test conditions, and also the use of one unit of a PV without a cooler that has the same solar cell number as a PV with a cooler. This paper proposes new methods that have the flexibility to be applied under various solar irradiance values. The new methods depend on a PV that has a single solar cell only, without a cooler, when executing the performance assessment for a PV with a cooler that has a known number of solar cells. As a result, the assessment cost can be significantly reduced. An experimental work is conducted for three PV cooler types and found that the performance assessment cost can be reduced by up to 33.33 %, by using the new methods, as compared to using the existing method. Hence, the new methods are cost effective. It is also shown that the experimental measurements are the same as the results obtained from the new methods. When the new method (FTDPD) is compared with the temperature-dependent photovoltaic power difference (ΔP) that is defined and derived, it is shown that the computational work can be reduced, because it has less influential parameters, thus, it is also a time-efficient method. PV cooler designers and manufacturers could be the possible users of the new methods.

Effects of thermal, elastic, and surface properties on the stability of SiC polytypes

SiC polytypes have been studied for decades, both experimentally and with atomistic simulations, yet no consensus has been reached on the factors that determine their stability and growth. Proposed governing factors are temperature-dependent differences in the bulk energy, biaxial strain induced through point defects, and surface properties. In this work, we investigate the thermodynamic stability of the 3C, 2H, 4H, and 6H polytypes with density functional theory (DFT) calculations. The small differences of the bulk energies between the polytypes can lead to intricate changes in their energetic ordering depending on the computational method. Therefore, we employ and compare various DFT codes, i.e., vasp, cp2k, and fhi-aims; exchange-correlation functionals, i.e., LDA, PBE, PBEsol, PW91, HSE06, SCAN, and RTPSS; and nine different van der Waals (vdW) corrections. At $T=0$ K, 4H-SiC is marginally more stable than 3C-SiC, and the stability further increases with temperature by including entropic effects from lattice vibrations. Neither the most advanced vdW corrections nor strain on the lattice have a significant effect on the relative polytype stability. We further investigate the energies of the (0001) polytype surfaces that are commonly exposed during epitaxial growth. For Si-terminated surfaces, we find 3C-SiC to be significantly more stable than 4H-SiC. We conclude that the difference in surface energy is likely the driving force for 3C-nucleation, whereas the difference in the bulk thermodynamic stability slightly favors the 4H and 6H polytypes. In order to describe the polytype stability during crystal growth correctly, it is thus crucial to take into account both of these effects.

An optimized protocol for assessment of sputum macrorheology in health and muco-obstructive lung disease

Background: Airway mucus provides important protective functions in health and abnormal viscoelasticity is a hallmark of muco-obstructive lung diseases such as cystic fibrosis (CF). However, previous studies of sputum macrorheology from healthy individuals and patients with CF using different experimental protocols yielded in part discrepant results and data on a systematic assessment across measurement settings and conditions remain limited. Objectives: The aim of this study was to develop an optimized and reliable protocol for standardized macrorheological measurements of airway mucus model systems and native human sputum from healthy individuals and patients with muco-obstructive lung disease. Methods: Oscillatory rheological shear measurements were performed using bovine submaxillary mucin (BSM) at different concentrations (2% and 10% solids) and sputum samples from healthy controls (n = 10) and patients with CF (n = 10). Viscoelastic properties were determined by amplitude and frequency sweeps at 25°C and 37°C with or without solvent trap using a cone-plate geometry. Results: Under saturated atmosphere, we did not observe any temperature-dependent differences in 2% and 10% BSM macrorheology, whereas in the absence of evaporation control 10% BSM demonstrated a significantly higher viscoelasticity at 37°C. Similarly, during the measurements without evaporation control at 37°C we observed a substantial increase in the storage modulus G′ and the loss modulus G″ of the highly viscoelastic CF sputum but not in the healthy sputum. Conclusion: Our data show systematically higher viscoelasticity of CF compared to healthy sputum at 25°C and 37°C. For measurements at the higher temperature using a solvent trap to prevent evaporation is essential for macrorheological analysis of mucus model systems and native human sputum. Another interesting finding is that the viscoelastic properties are not much sensitive to the applied experimental deformation and yield robust results despite their delicate consistency. The optimized protocol resulting from this work will facilitate standardized quantitative assessment of abnormalities in viscoelastic properties of airway mucus and response to muco-active therapies in patients with CF and other muco-obstructive lung diseases.

On the role of pH and temperature on ground – and excited – state proton transfer of hydroxyflavones in lipidic bilayers of lecithin

Absorption and emission monitoring of bioactive flavonols, Hydroxyflavones (HFs), (3-HF, 3,6-diHF and 3,7-diHF), to explore their microenvironments as a function of pH and temperature in lipidic bi-layers of lecithin (EYPC), have been studied. The influence of lipidic bi-layers on the − OH groups deprotonation of HFs with several distribution in the vicinity of the polar phosphate groups of EYPC when pH changed as well as the position of −OH groups in the HFs structure on the excited-state intramolecular proton transfer (ESIPT), have been studied by fluorescence spectroscopy. It was found that at physiological pH, EYPC leads to the increase of the quantum yield of Tautomer fluorescence for HFs with multiple −OH groups. There is a temperature-dependent difference in the ESIPT process which takes place in HFs/EYPC systems. The findings are relevant for in vivo and in vitro studies of the oxidative stress process which involves cell membranes, where HFs are used as sensitive fluorescence probes.

Stereolithography 3D Printing of a Heat Exchanger for Advanced Temperature Control in Wire Myography.

We report the additive manufacturing of a heat-exchange device that can be used as a cooling accessory in a wire myograph. Wire myography is used for measuring vasomotor responses in small resistance arteries; however, the commercially available devices are not capable of active cooling. Here, we critically evaluated a transparent resin material, in terms of mechanical, structural, and thermal behavior. Tensile strength tests (67.66 ± 1.31 MPa), Charpy impact strength test (20.70 ± 2.30 kJ/m2), and Shore D hardness measurements (83.0 ± 0.47) underlined the mechanical stability of the material, supported by digital microscopy, which revealed a glass-like structure. Differential scanning calorimetry with thermogravimetry analysis and thermal conductivity measurements showed heat stability until ~250 °C and effective heat insulation. The 3D-printed heat exchanger was tested in thermophysiology experiments measuring the vasomotor responses of rat tail arteries at different temperatures (13, 16, and 36 °C). The heat-exchange device was successfully used as an accessory of the wire myograph system to cool down the experimental chambers and steadily maintain the targeted temperatures. We observed temperature-dependent differences in the vasoconstriction induced by phenylephrine and KCl. In conclusion, the transparent resin material can be used in additive manufacturing of heat-exchange devices for biomedical research, such as wire myography. Our animal experiments underline the importance of temperature-dependent physiological mechanisms, which should be further studied to understand the background of the thermal changes and their consequences.

Temperature-dependent growth and sexuality of the ciguatoxin producer dinoflagellate Gambierdiscus spp. in cultures established from the Canary Islands

Benthic dinoflagellates of the genus Gambierdiscus produce ciguatoxins, compounds that when metabolized in fish and consumed by humans cause ciguatera poisoning (CP). This syndrome, which is widespread in tropical and subtropical regions, has recently been reported also in subtropical-temperate latitudes such as the Canary Islands where CP events have been regularly detected since 2004. This study examined the effect of temperature on the growth of Gambierdiscus isolated from Canary waters: G. australes, G. caribaeus, G. carolinianus, G. excentricus, and G. silvae. From the temperature vs. growth curves, the maximum growth (µm), optimum temperature range for growth (Topt), and the temperature yielding maximum growth (Tm) were estimated for each species. The results revealed temperature-dependent differences in the growth parameters. G. caribaeus had the highest Tm and Topt, followed by G. australes, G. carolinianus, G. silvae, and G excentricus. G. australes tolerated the widest range of temperatures (from 15 °C to 29 °C), which may explain its broader geographic distribution, both worldwide and across the Canary archipelago. Neither G. excentricus nor G. silvae survived at 29 °C whereas G. caribaeus reached mean growth rates (± standard deviation) up to 0.19 ± 0.01 div.day−1 at that temperature, followed by G. australes (0.16 ± 0.01 div.day−1) and G. carolinianus (0.14 ± 0.04 div.day−1). G. caribaeus showed no measurable growth at 19°C, whereas G. excentricus and G. silvae along with G. australes appeared as the species better adapted to lower temperatures. In an intraspecific variability study of 12 strains of G. australes, the mean (± standard deviation) of µm and Tm were 0.17 ± 0.01 div.day−1 and 27.7 ± 0.5 °C, respectively. An analysis of the shapes and position of the cell nuclei at the different temperatures showed that nuclei characteristic of vegetative cells appeared mainly at 26 °C but extreme temperatures resulted in nuclei with a more variable morphology. The presence of putative zygotes at extreme temperatures (17 °C, 19 °C and 29 °C) suggests that sexual reproduction is promoted as an adaptive strategy which could play an important role in the expansion of geographic distribution of Gambierdiscus species.

Temperature-dependent effects of house fly proto-Y chromosomes on gene expression could be responsible for fitness differences that maintain polygenic sex determination.

Sex determination, the developmental process by which sexually dimorphic phenotypes are established, evolves fast. Evolutionary turnover in a sex determination pathway may occur via selection on alleles that are genetically linked to a new master sex determining locus on a newly formed proto-sex chromosome. Species with polygenic sex determination, in which master regulatory genes are found on multiple different proto-sex chromosomes, are informative models to study the evolution of sex determination and sex chromosomes. House flies are such a model system, with male determining loci possible on all six chromosomes and a female-determiner on one of the chromosomes as well. The two most common male-determining proto-Y chromosomes form latitudinal clines on multiple continents, suggesting that temperature variation is an important selection pressure responsible for maintaining polygenic sex determination in this species. Temperature-dependent fitness effects could be manifested through temperature-dependent gene expression differences across proto-Y chromosome genotypes. These gene expression differences may be the result of cis regulatory variants that affect the expression of genes on the proto-sex chromosomes, or trans effects of the proto-Y chromosomes on genes elswhere in the genome. We used RNA-seq to identify genes whose expression depends on proto-Y chromosome genotype and temperature in adult male house flies. We found no evidence for ecologically meaningful temperature-dependent expression differences of sex determining genes between male genotypes, but we were probably not sampling an appropriate developmental time-point to identify such effects. In contrast, we identified many other genes whose expression depends on the interaction between proto-Y chromosome genotype and temperature, including genes that encode proteins involved in reproduction, metabolism, lifespan, stress response, and immunity. Notably, genes with genotype-by-temperature interactions on expression were not enriched on the proto-sex chromosomes. Moreover, there was no evidence that temperature-dependent expression is driven by chromosome-wide cis-regulatory divergence between the proto-Y and proto-X alleles. Therefore, if temperature-dependent gene expression is responsible for differences in phenotypes and fitness of proto-Y genotypes across house fly populations, these effects are driven by a small number of temperature-dependent alleles on the proto-Y chromosomes that may have trans effects on the expression of genes on other chromosomes.

Proteome plasticity in response to persistent environmental change

Temperature is a variable component of the environment, and all organisms must deal with or adapt to temperature change. Acute temperature change activates cellular stress responses, resulting in refolding or removal of damaged proteins. However, how organisms adapt to long-term temperature change remains largely unexplored. Here we report that budding yeast responds to long-term high temperature challenge by switching from chaperone induction to reduction of temperature-sensitive proteins and re-localizing a portion of its proteome. Surprisingly, we also find that many proteins adopt an alternative conformation. Using Fet3p as an example, we find that the temperature-dependent conformational difference is accompanied by distinct thermostability, subcellular localization, and, importantly, cellular functions. We postulate that, in addition to the known mechanisms of adaptation, conformational plasticity allows some polypeptides to acquire new biophysical properties and functions when environmental change endures.

Hypercooling limit and physical properties of liquid MoNbReTaW refractory high-entropy alloy

ABSTRACT The thermophysical properties of refractory MoNbReTaW high-entropy alloy in both supercooled liquid and high-temperature solid states were explored by an electrostatic levitation technique. The maximum supercooling attains 504 K, and the hypercooling limit is derived as 571 K. The liquid density at liquidus temperature is measured to be 13.3 g cm−3, which increases linearly with decreasing temperature at a slope of 6.83 × 10−4 g cm−3 K−1. The liquid alloy exhibits 5.3% relative volume shrinkage during crystallization. The thermal expansion coefficient of liquid and solid alloy at liquidus temperature are determined as 5.0 × 10−5 K−1 and 3.6 ×10−5 K−1, respectively. The liquid specific heat at liquidus temperature is found to be 38.2 J mol−1 K−1, and basically displays a linear decreasing tendency with temperature. According to the calculated enthalpy of fusion 24.7 kJ mol−1 and measured specific heats, the temperature-dependent entropy and Gibbs free energy difference between supercooled liquid and crystalline solid are obtained.

High-intensity illumination treatments against LeTID – Intensity and temperature dependence of stability and inline feasibility

We study the mitigation of light- and elevated temperature-induced degradation (LeTID) with high-intensity illumination treatments, placing special emphasis on inline feasibility. After the treatments, we investigate the stability upon degradation conditions close to the recently suggested standard, which allows estimating the LeTID behavior during the operating lifetime of solar modules in the field. Subsequently, we map the stability at different treatment intensities and temperatures achievable with an air-cooled tool. We show that, when applying short treatment times, the stability improves with increasing treatment intensity and deteriorates steeply with rising temperature above an optimum region around 250 °C. However, these intensity- and temperature-dependent differences largely vanish when increasing the treatment time sufficiently. We also investigate the significance of darkness/illumination during the cooling ramp from the treatment temperature in view of the LeTID stability. We discuss our results based on suggested defect models of LeTID, and provide hypotheses of the origin of the instabilities observed at the high treatment temperatures. After identifying optimal treatments, we demonstrate that the energy yield loss due to LeTID reduces by over 60% after an inline-feasible process consisting of only 30 s of high-intensity illumination, combined with cooling of the samples from the process temperature under a lower-intensity illumination.

Martensitic Transformation Induced by Electro-Chemical Polishing in Metastable Austenitic Stainless Steel

We determined that a severe martensitic transformation during electrochemical polishing (EP) in 16Cr-5Ni metastable austenitic stainless steel was caused solely by EP. The specimen was treated by EP, then sealed in a quartz tube to protect the surface, then annealed at 1150 °C to form a single austenite phase, and again subjected to EP. As the duration of the second EP increased, the fraction of martensite increased to 72.2% when the duration is 160s at 20V of voltage. However, Ferritescope measurements showed that the martensite fraction of the whole specimen was < 1%; comparison of these results suggests that the martensite transformation by EP was limited to the surface. Calculation of the temperature-dependent difference in Gibbs free energy between α’ martensite and austenite confirmed that the energy applied to the specimen during EP is sufficient to cause martensitic transformation at room temperature.