Temperature-induced Changes Research Articles

Abnormal reduction and luminescence properties of Sm2+-doped Sr5(PO4)3Cl prepared by solution combustion synthesis

Sm-doped Sr5(PO4)3Cl was prepared by a solution combustion synthesis in the air atmosphere. The pure hexagonal phases of the samples were confirmed via the XRD, Raman, and FT-IR measurements. The typical microrod shape of the products was also demonstrated by SEM, TEM, and HRTEM images. The spectral properties and lifetimes were applied to characterize the luminescence of the samples as-prepared and subsequently heated in the air atmosphere. The luminescence of as-prepared Sm-doped Sr5(PO4)3Cl contains a broad emission band and a group of narrow lines, which are ascribed to the radiative transitions of 4f5d→4f and 5D0→7FJ (J = 0, 1, 2) of Sm2+ ions, respectively. It indicates that the Sm3+ can be successfully reduced to Sm2+ ions in hexagonal Sr5(PO4)3Cl prepared by combustion synthesis. The temperature dependent luminescence spectra and decay curves of Sm2+ were measured in a very wide temperature region from 10 K to 300 K. The thermal quenching and activation energy of Sm2+ doped Sr5(PO4)3Cl were reported. The crystal field energy level diagram and excitation mechanism of Sm2+ ions-doped Sr5(PO4)3Cl were characterized by the high resolution luminescence at low temperature. The luminescence of Sm2+ in Sr5(PO4)3Cl shows a great dependence on heating temperature in the air atmosphere (50–700 °C). The heating treatments at the elevated temperature depress Sm2+ emission along with the appearance of Sm3+ ions. The temperature-induced changes in the modification of the spectral components could be applied as potential luminescence thermometry.

Predictability of initial hydrogeochemical effects induced by short-term infiltration of ∼75 °C hot water into a shallow glaciogenic aquifer

Despite their potential in heating supply systems, thus far high-temperature aquifer thermal energy storages (HT-ATES) currently lack widespread application. Reducing the potential risks by improving the predictability of hydrogeochemical processes accelerated or initiated at elevated temperatures might promote the development of this technology. Therefore, we report the results of a short-term hot water infiltration field test with subsurface temperatures above 70 °C, along with associated laboratory batch tests at 10, 40 and 70 °C for 28 sediment samples to determine their usability for geochemical prediction.Most groundwater components had lower maximal concentrations and smaller concentration ranges in field samples compared to the batch tests. This indicates that the strongest geochemical effects observed in laboratory tests with sufficient site-specific sediment samples will likely be attenuated at the field scale. A comparison of field measurements with predicted concentration ranges, based on temperature induced relative concentration changes from the batch tests, revealed that the predictive power was greatest, where the hot infiltrated water had cooled least and the strongest geochemical effects occurred. The batch test-based predictions showed the best accordance with field data for components, with significant temperature-induced concentration changes related to ion exchange and (de)sorption processes. However, accurate prediction of concentration changes based on other processes, e.g. mineral dissolution, and downstream reversals in concentrations, requires further investigation.The here presented procedure enables the prediction of maximal expectable temperature-dependant concentration changes for most environmentally relevant ancillary groundwater components, e.g. As, with limited effort.

Temperature-induced pH changes govern hydrate transformation during cooling crystallization of potassium acid phthalate

Achieving greater control on crystallization to obtain desired crystal structure and morphology is a significant challenge in material synthesis. The highly stochastic nature of crystallization makes it necessary to conduct thorough experimental and computational investigations of crystalline materials. Polymorphic transformation, including hydrate formation during crystallization of potassium acid phthalate (KAP) is one such example. The hydrated form of crystals can appear during crystallization when water interacts strongly with functional groups of solute molecules, leading to its inclusion into the crystal lattice. Here, we show the temperature-dependent transformation of anhydrous KAP (form-I) to monohydrate KAP (form-II) crystal. Such polymorphic and associated morphological changes as a function of temperature and supersaturation are studied using in-situ hot-stage optical microscopy and validated with morphology domain analysis. While the measured growth rates and morphologies do not vary significantly with supersaturation, they show a stronger temperature dependence due to the formation of hydrated forms. The computational results uncover the previously unknown effect of temperature-dependent pH increase, which causes deprotonation of the carboxylic group leading to destabilization of [110] facets. The appearance of hydrated form seems to be due to temperature-induced pH changes. These results provide fundamental insights into the mechanism of hydrate transformations during cooling crystallization.

Fine-Tuning Window Apertures in ZIF-8/67 Frameworks by Metal Ions and Temperature for High-Efficiency Molecular Sieving of Xylenes.

Separation of structurally similar components from their mixtures is one of the most promising applications of metal-organic frameworks (MOFs). A high efficiency of such molecular sieving requires fine tuning of the MOF structure. In this work, we investigate subtle metal- and temperature-induced changes in window dimensions of zeolitic imidazolate frameworks (ZIF-8(Zn) and ZIF-67(Co)) and apply such structural tuning for efficient separation of xylene isomers (p-, m-, and o-xylenes). The use of Co instead of Zn favorably modifies window geometry: it accelerates the diffusion of all components by a factor of 2-3 while maintaining closely the same separation efficiency as that of ZIF-8(Zn). Outstanding selectivity above 18:1 and faster isolation of demanded p-xylene from the ternary mixture using ZIF-67(Co) have been demonstrated at room temperature, opening new horizons for its energy-efficient xylene separation. More generally, our findings suggest the prospective ways to tune various MOFs for target liquid-state separations.

Structural insights into the temperature-induced colour changes of [(CH3)2NH2]2NiCl4

Structural insights into the temperature-induced colour changes of [(CH₃)₂NH₂]₂NiCl₄

Full-range behavior of FRP-to-concrete bonded joints subjected to combined effects of loading and temperature variation

Concrete structures strengthened with externally bonded fiber-reinforced polymer (FRP) composites are likely to experience significant temperature variations (i.e., thermal loadings) due to daily and seasonal temperature changes or possible fire exposure during service life. Such thermal loadings may lead to changes in the mechanical properties of components (including FRP, bonding adhesive and concrete substrate) and induce interfacial thermal stress due to the thermal incompatibility between FRP and concrete. A limited bond length is usually adopted to investigate the bond behavior (e.g., the local bond-slip characteristics) of the FRP-to-concrete interface under temperature variations. This paper presents an analytical study for the first time to predict the full-range deformation behavior of a mechanically loaded FRP-to-concrete bonded joint with a limited bond length under temperature variations. The solution is in a closed-form manner and has enabled isolation of the interfacial thermal stress effect from the temperature-induced changes of material properties, thereby leading to an accurate calibration of the bond-slip characteristics and the interfacial fracture energy. The closed-form analytical solution has been verified by comparing the analytical predictions with the existing experimental and numerical results in the literature. To further understand the mechanism of the FRP-to-concrete interface under combined thermal and mechanical loadings, the effects of thermal stress and bond length on the interfacial responses and the full-range deformation behavior of the FRP-to-concrete interface are comprehensibly analyzed.

Temperature sensing using ruby coatings created by plasma electrolytic oxidation

Thermographic properties of Cr3+-doped Al2O3 coatings created by plasma electrolytic oxidation (PEO) are investigated. Scanning electron microscopy revealed dense coatings uniformly distributed over the aluminum surface with uniform elemental maps, confirming homogeneous distribution of chromium ions. X-ray diffraction analysis shows that created coatings consist of a mixture of alpha and gamma phase of alumina and that alpha-to-gamma phase ratio increases with PEO processing time. Room-temperature photoluminescent measurements revealed two deep-red, sharp emissions placed at 694 nm (R1 line) and 693 nm (R2 line) typical for Cr3+ in Al2O3 octahedral configuration. No evidence of broad 680−800 nm emission typical for alumina gamma phase is observed and emissions were predominantly attributed to the ruby α-Al2O3:Cr3+. The temperature is obtained from the coating’s emission using temperature-induced changes in: i) band shift of the R1 line, (ii) luminescence intensity ratio (LIR) between two Cr3+ R1,2 lines, and (iii) lifetime of the Cr3+ red emission with maximal sensitivities of 0.2 cm−1 K−1 @ 550 K, 4.8 % K−1 @ 20 K and 0.9 % K−1 @ 450 K, respectively.

Trans-seasonal activation of the neuroendocrine reproductive axis: Low-temperature winter dormancy modulates gonadotropin-releasing hormone neurons in garter snakes.

All animals use external cues from the environment to accurately time life-history events. How the brain decodes environmental stimuli to effect changes in physiology and behavior, however, is poorly understood, particularly with regard to supplementary environmental cues such as temperature. We asked if low-temperature dormancy alters the synthesis and/or release of gonadotropin-releasing hormone (GnRH). We used the well-studied red-sided garter snake (Thamnophis sirtalis) for this study, as low-temperature exposure is both necessary and sufficient to induce reproduction in northern populations of this species. Snakes were collected from the field and hibernated at 4°C or 10°C in complete darkness for up to 16 weeks. In males, increasing duration of low-temperature dormancy significantly increased GnRH-immunoreactive cell number and GnRH soma size (a proxy for relative cell activity) in the forebrain. These changes mirrored those in male reproductive behavior (reported previously) and plasma androgen concentrations. The changes in GnRH cell area observed in males were specific to the neuroendocrine population of cells in the medial preoptic area; soma size in the rostral GnRH cells did not change. Finally, temperature-induced changes in GnRH were sexually dimorphic: neither hibernation temperature nor the duration of winter dormancy significantly modulated GnRH cell number or soma size in females, despite the fact that plasma estradiol and corticosterone increased significantly in response to both. These data demonstrate that the neuroendocrine GnRH system is sensitive to environmental temperature and suggest that GnRH neurons play a conserved but trans-seasonal role in mediating changes in reproductive physiology and behavior in dissociated breeders.

Cold acclimation induces life stage-specific responses in the cardiac proteome of western painted turtles (Chrysemys picta bellii): implications for anoxia tolerance.

Western painted turtles (Chrysemys picta bellii) are the most anoxia-tolerant tetrapod. Survival time improves at low temperature and during ontogeny, such that adults acclimated to 3°C survive far longer without oxygen than either warm-acclimated adults or cold-acclimated hatchlings. As protein synthesis is rapidly suppressed to save energy at the onset of anoxia exposure, this study tested the hypothesis that cold acclimation would evoke preparatory changes in protein expression to support enhanced anoxia survival in adult but not hatchling turtles. To test this, adult and hatchling turtles were acclimated to either 20°C (warm) or 3°C (cold) for 5 weeks, and then the heart ventricles were collected for quantitative proteomic analysis. The relative abundance of 1316 identified proteins was compared between temperatures and developmental stages. The effect of cold acclimation on the cardiac proteome was only evident in the context of an interaction with life stage, suggesting that ontogenic differences in anoxia tolerance may be predicated on successful maturation of the heart. The main differences between the hatchling and adult cardiac proteomes reflect an increase in metabolic scope with age that included more myoglobin and increased investment in both aerobic and anaerobic energy pathways. Mitochondrial structure and function were key targets of the life stage- and temperature-induced changes to the cardiac proteome, including reduced Complex II proteins in cold-acclimated adults that may help down-regulate the electron transport system and avoid succinate accumulation during anoxia. Therefore, targeted cold-induced changes to the cardiac proteome may be a contributing mechanism for stage-specific anoxia tolerance in turtles.

Borderline first-order magnetic phase transition in AlFe2B2

The thermal evolution of lattice parameters coupled with heat capacity data provide insight into tailorable magnetism-structure attributes in the orthorhombic compound AlFe2B2 that was synthesized with and without small additions of gallium. Temperature-dependent X-ray powder diffraction experiments conducted through the magnetic phase transition reveal that the a- and b-parameters of both samples increase with increasing temperature while the c-parameter decreases. While a weak volumetric thermal expansion is noted over a range of temperatures well below and above the magnetic phase transition, anomalous behavior was observed within the phase transition region itself to reveal a magnetostructural phase transition with borderline first-order character in the Ga-modified sample but of more second-order character in the Ga-free sample. It is established that the nearest-neighbor Fe-Fe interatomic distance within the (ab)-plane plays a dominant role in influencing the magneto-functional response of these compounds. The magnetocaloric properties are discussed in the context of temperature-induced changes of the interatomic bonding that are influenced by the hypothesized presence of iron antisite defects in the AlFe2B2 lattice.

Drying and temperature induced conformational changes of nucleic acids and stallion sperm chromatin in trehalose preservation formulations

Even though dried sperm is not viable, it can be used for fertilization as long as its chromatin remains intact. In this study, we investigated drying- and temperature-induced conformational changes of nucleic acids and stallion sperm chromatin. Sperm was diluted in preservation formulations with and without sugar/albumin and subjected to convective drying at elevated temperatures on glass substrates. Accumulation of reactive oxygen species was studied during storage at different temperatures, and the sperm chromatin structure assay was used to assess DNA damage. Fourier transform infrared spectroscopy was used to identify dehydration and storage induced conformational changes in isolated DNA and sperm chromatin. Furthermore, hydrogen bonding in the preservation solutions associated with storage stability were investigated. Reactive oxygen species and DNA damage in dried sperm samples were found to accumulate with increasing storage temperature and storage duration. Non-reducing disaccharides (i.e., trehalose, sucrose) and albumin counteracted oxidative stress and preserved sperm chromatin during dried storage, whereas glucose increased DNA damage during storage. When sperm was dried in the presence of trehalose and albumin, no spectral changes were detected during storage at refrigeration temperatures, whereas under accelerated aging conditions, i.e., storage at 37 °C, spectral changes were detected indicating alterations in sperm chromatin structure.

Reversible changes in galactolipid saturation level and head group composition are associated with tolerance to postharvest chilling in tomato fruit

Chilling injury (CI) is a physiological disorder that results in a limitation for cold storage (CS) of many fruits and vegetables. The low temperature-induced changes in the properties and composition of cell membranes are involved in the response to chilling temperature and in the mechanism of CI and tolerance. We compared the changes in the lipid composition by gas chromatography-mass spectrometry before, immediately after CS, as well as during a 3-day subsequent period, of tomato fruits with different chilling-sensitivity: Micro-Tom (tolerant) and Minitomato (susceptible). The changes in linolenic acid content, double bond index and digalactosyldiacylglycerol/monogalactosyldiacylglycerol ratio (DGDG/MGDG) showed membrane fluidity adjustment, depending on the temperature. By a database search, we identified 18 membrane-bound fatty acid desaturase (FAD) genes and five DGDG synthases (DGD) genes that phylogenetically clustered into four and two subfamilies, respectively. The FAD and DGD genes were differentially expressed in response to CS, as determined by quantitative reverse transcriptase-polymerase chain reaction analysis. The data strongly suggest that reversion of CS-induced changes during the recovery period is important for the proper function of the membrane and tolerance to postharvest CI in tomato fruit. © 2021 Society of Chemical Industry.

Tensile Strength of Compacted Clays during Desiccation under Elevated Temperatures

Abstract The tensile strength of unsaturated soils is a critical factor controlling the initiation and propagation of desiccation cracks, which can threaten the structural integrity of natural and man-made earthen structures and slopes. Several engineering applications involve unsaturated soils subjected to elevated temperatures (e.g., earthen structure-atmospheric interaction under prolonged droughts, nuclear water disposal, energy piles, ground source heat pumps). Although the temperature dependency of desiccation cracking is demonstrated in the literature, critical gaps remain regarding the characterization of the tensile strength under elevated temperatures. The main objective of this study is to investigate the effect of elevated temperature on the tensile strength of unsaturated clays during desiccation. To accomplish this objective, a novel testing setup that can be used to directly determine soil tensile strength during desiccation was placed in an oven to measure the tensile strength of two compacted clayey soils of medium to high plasticity under different temperatures ranging from 20°C to 60°C. The clays are compacted at 95 % of their respective maximum dry unit weights over a range of water contents from dry to wet of optimum to investigate the influence of initial water content on tensile strength. The results demonstrated that the tensile strength decreased with increasing temperature. At the optimum water content, a tensile strength reduction of 36 % and 27 % in the highly plastic clay and the medium plastic clay, respectively, was observed when the temperature increased from 20°C to 60°C. Additionally, for the partially saturated condition, the initial water content affected the tensile strength significantly. Temperature-induced changes in key factors contributing to the tensile strength of unsaturated clays are discussed to provide further insight into tensile strength of clays at elevated temperatures. The findings of this study can contribute toward a more realistic analysis and design of earthen structures subjected to elevated temperatures.

Influence of Temperature on the Natural Vibration Characteristics of Simply Supported Reinforced Concrete Beam.

Natural vibration characteristics serve as one of the crucial references for bridge monitoring. However, temperature-induced changes in the natural vibration characteristics of bridge structures may exceed the impact of structural damage, thus causing some interference in damage identification. This study analyzed the influence of temperature on the natural vibration characteristics of simply supported beams, which is the most widely used bridge structure. The theoretical formula for the variation of the natural frequency of simply supported beams with temperature was proposed. The elastic modulus of simply supported beams in the range of −40 °C to 60 °C was acquired by means of the falling ball test and the theoretical formula and was compared with the elastic modulus obtained by the three-point bending test at room temperature (20 °C). In addition, the Midas/Civil finite-element simulation was carried out for the natural frequency of simply supported beams at different temperatures. The results showed that temperature was the main factor causing the variation of the natural frequency of simply supported beams. The linear negative correlation between the natural frequency of simply supported beams and their temperature were observed. The natural frequency of simply supported beams decreased by 0.148% for every 1 °C increase. This research contributed to the further understanding of the natural vibration characteristics of simply supported beams under the influence of temperature so as to provide references for natural frequency monitoring and damage identification of beam bridges.

Size dependent correlation between structure and apparent stiffness of viral DNA during temperature variation

Nucleic acid is indispensable to most viruses, and its mechanical property is an important factor for virus infectivity. Recent experiments found a temperature dependence of viral apparent stiffness, which stirred up controversy if apparent stiffness variation was ascribed to temperature-dependent structure variation of viral DNA. This paper is aimed to clarify this controversy by exploring the mechanism in apparent stiffness variation of viral DNA. A multi-scale correlation between microscopic structure of viral DNA and its apparent stiffness is formulated by presenting an alternative mesoscopic free energy model of viral DNA with the inclusion of its two-domain structural feature. Results reveal that the increasing temperature promotes DNA structural transformation from order to disorder, larger viral size will induce more dramatic DNA structural transformation, and this size-dependent temperature effect of viral DNA structure leads to corresponding change of its free energy and apparent stiffness. These temperature-induced changes in DNA structure, energy, stiffness are reflection of competition between microscopic interactions of ordered and disordered DNA domains, and the ordered DNA domain dominates the changes of general viral DNA structure and energy. The results can provide insights into potential methods to prevent viral infection disease or to regulate gene delivery.

Temperature-induced changes in polymer-based fractal patterns due to Ag metal aggregation

The present study throws light on the formation of silver fractal patterns when temperature treatment is given to the chitosan–AgNO3 solution for different temperatures and time periods. Temperature treatment results in both an enhanced degradation of the polymer (i.e., chitosan) and reduction rate of Ag+ ions to the silver particles. Small-sized clusters of silver particles form in the polymeric matrix, which were confirmed by ultraviolet–visible spectroscopy and scanning electron microscopy. Silver clusters aggregate giving different patterns due to the different temperature treatments. Changes in Fourier transform infrared spectra were invoked to explain the reduction of the Ag+ ions and the degradation mechanism of chitosan due to the temperature exposure. Degradation of chitosan due to temperature treatment results in a change in the viscosity. Viscosity measurements were taken by using an Ubbelohde viscometer for the chitosan–AgNO3 system as a function of storage time and temperature treatment time. A decrement in the viscosity was observed in all the cases, which confirms the degradation of chitosan both with and without complexation of salt (AgNO3). The degradation behavior of the polymer in different experimental conditions significantly modifies the aggregation patterns due to silver particles.

Temperature differently affected methanogenic pathways and microbial communities in sub-Antarctic freshwater ecosystems

Freshwater ecosystems are responsible for an important part of the methane (CH4) emissions which are likely to change with global warming. This study aims to evaluate temperature-induced (from 5 to 20 °C) changes on microbial community structure and methanogenic pathways in five sub-Antarctic lake sediments from Magallanes strait to Cape Horn, Chile. We combined in situ CH4 flux measurements, CH4 production rates (MPRs), gene abundance quantification and microbial community structure analysis (metabarcoding of the 16S rRNA gene). Under unamended conditions, a temperature increase of 5 °C doubled MPR while microbial community structure was not affected. Stimulation of methanogenesis by methanogenic precursors as acetate and H2/CO2, resulted in an increase of MPRs up to 127-fold and 19-fold, respectively, as well as an enrichment of mcrA-carriers strikingly stronger under acetate amendment. At low temperatures, H2/CO2-derived MPRs were considerably lower (down to 160-fold lower) than the acetate-derived MPRs, but the contribution of hydrogenotrophic methanogenesis increased with temperature. Temperature dependence of MPRs was significantly higher in incubations spiked with H2/CO2 (c. 1.9 eV) compared to incubations spiked with acetate or unamended (c. 0.8 eV). Temperature was not found to shape the total microbial community structure, that rather exhibited a site-specific variability among the studied lakes. However, the methanogenic archaeal community structure was driven by amended methanogenic precursors with a dominance of Methanobacterium in H2/CO2-based incubations and Methanosarcina in acetate-based incubations. We also suggested the importance of acetogenic H2-production outcompeting hydrogenotrohic methanogenesis especially at low temperatures, further supported by homoacetogen proportion in the microcosm communities. The combination of in situ-, and laboratory-based measurements and molecular approaches indicates that the hydrogenotrophic pathway may become more important with increasing temperatures than the acetoclastic pathway. In a continuously warming environment driven by climate change, such issues are crucial and may receive more attention.

Effect of pH and temperature on the aggregation behaviour of dirhamnolipid biosurfactant. An experimental and molecular dynamics study

HypothesisPseudomonas aeruginosa dirhamnolipid (diRL) has been shown to form aggregates of different size and structure, under various conditions. Due to the presence of a carboxyl group in the molecule, it is expected that pH would strongly affect this aggregation behaviour. In addition, preliminary observations of temperature-induced changes in the states of aggregation of diRL supported the need of further investigation. ExperimentsA systematic experimental study, using differential scanning calorimetry (DSC), small-angle Xray diffraction (SAXD), and Fourier-transform infrared spectroscopy (FTIR), has been carried out to characterize pH and temperature driven changes in the aggregation behavior of diRL biosurfactant. Molecular dynamics (MD) simulations, supported by the experimental results, allowed depicting molecular details on formation of diRL membranes and other aggregated structures under various physicochemical conditions. FindingsDiRL could adopt fairly organized multilayered structures (membranes) at low pH and temperature, which became highly disordered upon increasing either of these parameters. The effect of pH on the gauche/all-trans conformer ratio of the diRL acyl chains was not of significance, whereas temperature-induced effects were observed. For the first time it is described that diRL underwent an endothermic thermotropic transition with Tc = 34 °C as observed by DSC, at pH 4.5 (protonated diRL), but not at pH 7.4 (unprotonated diRL). FTIR confirmed these findings, showing a significant additional disordering of the all-trans acyl chains upon increasing temperature around that same value in the protonated form, an effect not observed for the dissociated form of the biosurfactant. In addition, at pH 7.4, changing temperature did not modify the hydration state of the polar moiety of diRL, whereas at pH 4.5 a significant decrease in the hydration state around 34 °C took place. SAXD data showed that protonated diRL formed multilayered structures at 20 °C, which converted into poorly correlated layers at 50 °C. MD simulations supported these findings, showing that the membrane-like structures formed by protonated diRL at 20 °C became unstable at higher temperatures, tending to form other structures, which could be micelles or other type of layered structures, whereas the negatively charged form of diRL organized in micelle-type aggregates in the whole range of temperature under study.

Temperature-induced alteration of the extracellular matrix in the tropical sea anemone, Exaiptasia pallida

Coral bleaching results from the loss of the endosymbiotic dinoflagellate the cells of coral. The symbionts provide photosynthetic products for nourishment of the coral, and loss of the symbiont can result in death of the coral. Many stressors can cause coral bleaching, but we are focusing on the effect of increased water temperature in this research because of rising oceanic temperatures. We are how investigating how increased temperature affects the extracellular matrix (ECM) using the tropical sea anemone, Exaiptasia pallida as our model organism, since this anemone has similar physiological characteristics and similar symbionts as coral. Research on the effects of a heat-shock (from 25°C to 30°C) in anemones embedded, sectioned, and then stained with the Russel-Movat Pentachrome stain showed that the mesoglea of the anemone, was altered after a 12 hour heat-shock compared to control anemones. To confirm these findings, staining with an additional ECM stain, Masson’s Trichrome, will be conducted. Additionally, we are investigating how alteration in the ECM because of increased temperature affects apoptosis to determine if there is a positive correlation between temperature-induced changes in the ECM and loss of cells through apoptosis. Results from these experiments will help us better understand the timing and consequences of temperature-induced breakdown of the coral-algal symbiosis.

The Melt Heat Treatment and the Structural Changes in ZhS6U and Inconel 718

One of the most curious phenomena observed in metal melts is the temperature-induced liquid-liquid structural changes. As a result of the thermal treatment lead to LLT, a more equilibrium and micro-uniform melt consisting of atomic associations is formed. In nickel alloy melts, the changes that have occurred are irreversible and have a significant effect on the formation of the final structure and the mechanical properties of the metal in the solid state after its crystallization. In addition, they are the starting point for the scientific substantiation of new technological modes of smelting and heat treatment of alloys, which further improve their operational properties, as well as reduce metallurgical defects and production waste, and rational use of expensive ligands. All this in general will lead to a significant increase in the performance of melts and metal products. Our work is devoted to the experimental confirmation of the LLT transition in two common nickel-based alloys by a non-invasive electromagnetic method.