Gradual Decrease In Temperature Research Articles

Effect of gradual increase and decrease in temperature on innate, cellular and humoral immunity in striped hamsters

Effect of gradual increase and decrease in temperature on innate, cellular and humoral immunity in striped hamsters

Low-temperature superplastic deformation of EK61 and EP975 wrought nickel-based superalloys with an ultrafine-grained structure

It is shown that thermomechanical treatment (TMT) of the EK61 superalloy with a strain rate (ε∙) of 10−3 s−1 and a gradual decrease in the treatment temperature from (0.92 – 0.65)Tδ leads to the transformation of the initial coarse-grained structure into an ultrafine-grained (UFG) mixed type structure. Such a mixed UFG microstructure consists of γ-phase grains and δ-phase particles 0.3 μm in size and relatively large particles of the δ-phase up to 2 μm in size. The EK61 superalloy having such a microstructure exhibits low-temperature superplasticity in the temperature range of 700 – 900°C, the maximum characteristics of which are achieved at 850°C and ε∙ =10−3 s−1. Low-temperature TMT in the temperature range of (0.84 – 0.8)Тγ' also leads to the formation of an UFG structure in the EP975 superalloy. The UFG microstructure of the EP975 superalloy consists of γ-phase grains and γ'-phase particles 0.5 μm in size. And there are relatively large particles of the γ'-phase up to 3.5 μm in size of a globular-shaped form. The EP975 superalloy with such a structure exhibits low-temperature superplasticity in the temperature range of 900 –1000°C, the maximum characteristics of which are achieved at 1000°C and ε∙ =10−3 s−1.

Geochemical Characterization of Laminated Crystalline Crust Travertines Formed by Ca2+-Deficient Hot Springs at Sobcha (China)

Travertines formed of crystalline crust have been widely reported, but there has not been focus on their geochemical characteristics. We therefore carefully conducted a series of geochemical investigations and U-Th dating on a travertine mound mainly composed of crystalline crust from Sobcha (southwest China) to determine their geochemical features and geological implications. The Sobcha travertines dominantly consist of granular crystals and fan crystals and show δ13C from 3.4‰ to 4.9‰ V-PDB, δ18O from −26.7‰ to −23.7‰ V-PDB, and 87Sr/86Sr from 0.712458 to 0.712951. When normalized to PASS, the Sobcha travertines exhibit MREE enrichment relative to HREE and LREE, HREE enrichment relative to LREE, and positive Eu anomalies. The δ13C signatures and mother CO2 evaluation of the Sobcha travertines show that the Sobcha travertines were thermogene travertines largely receiving mother CO2 from (upper) mantle (i.e., magmatic CO2) or a mixture of soil-derived CO2 and CO2 related to carbonate decarbonation. The 87Sr/86Sr of the Sobcha travertines is out of the 87Sr/86Sr ranges of local deposits exposed at Sobcha and surrounding areas but is well matched with the mean 87Sr/86Sr of Nadi Kangri volcanic rocks which cropped out to the northeast of the studied travertines (over 20 km away). This might indicate the important role of the Nadi Kangri volcanic rocks in suppling Sr to the studied travertines, but more studies are required. The LREE depletion compared to MREE and HREE in the Sobcha travertines was interpreted to be caused by the difference in geochemical mobility between LREEs and HREEs during water–rock interaction at depth, while the MREE enrichment compared to HREE was considered to be most likely inherited from reservoir/aquifer rocks. The positive Eu anomalies of the Sobcha travertines may result from very high reservoir temperatures and/or preferential dissolution of Eu-rich minerals/rocks (especially plagioclase). The Sobcha travertine mounds displays no or very slight vertical variations in δ13C, 87Sr/86Sr, and REE patterns, indicating the compositional stability of mother CO2 and paleo-fluids. However, a significant vertical increase in δ18O was observed and was explained as the result of gradual water temperature decrease related to climate cooling, self-closure of the vents, or mound vertical growth. The findings in this study might help us better understand the deposition of crystalline crust in Ca2+-deficient hot spring systems.

Analysis and numerical simulation of temperature measurements made on earth and from space

The sum of all currently known facts confirms the existence of a global warming process. The development models of this process are statistical in nature and often do not take into account the specifics of local conditions. This fact confirms our analysis of measurements of the average annual surface air temperature during the period 1980–2019 in the city of Krasnodar (Russia). We used data from ground based (World Data Center) and space based (POWER project) measurements. A comparison of the data showed that the discrepancies in ground and space based measurements of surface air temperatures until 1990 do not exceed the data error (s=±0.7 °C). After 1990, the most significant short-term discrepancies were observed in 2014 (−1.12°С) and 2016 (1.33°С). An analysis of the forecast model of the Earth's surface air average annual temperature for 1918–2020 indicates a gradual decrease in the average annual temperature even in the presence of short-term impulses of its increase. The rate of decrease in the average annual temperature from ground based observations is slightly higher than from space based observations, which is probably due to a more complete consideration of local conditions in ground based observations.

An Evaluation to the Performance of Evacuated Tube Solar Heaters for Arid and Hot Areas

Solar energy applications could be the best alternative to the conventional fuels for the purposes of domestic, water and space heating and some industries in the sunny, arid, and hot areas. In the present study, the performance of an evacuated tube solar heater for water heating for months of February and March was experimentally investigated. This was performed in a hot and arid area (Nasiriya City, South of Iraq). A solar heater with ten evacuated tube solar collectors with a capacity of 100 liter was used in the experiments. Each evacuated tube had a length of 1.8 m with an outside diameter of 8 cm. It was observed that for the two selected months, water temperature of the solar heater reached a maximum more than 70°C during sunny days with no heat extraction from the tank of the solar heater. Moreover, heat was extracted from the solar collector with four different flowrates 0.5, 0.75, 1, and 1.25 l/min, respectively. The results showed that temperature of the solar heater behaved differently from the static situation. When the heat extraction begun, there was a gradual and noticeable decrease in the water temperature of the heater. The observed decrease was slight with the lowest flowrate (0.25 l/m) and becomes sharp with the highest flowrate (1.25 l/min). However, water temperature of the solar heater remained higher than 40°C for the investigated flowrates except the case of 1.25 l/min. The results showed that evacuated tube solar heater can work efficiently in arid and hot areas in winter and spring seasons when the conditions of solar radiation are suitable.

Exploring the role of preferential solvation in the stability of globular proteins through the study of ovalbumin interaction with organic additives

<abstract> <p>The impact of denaturing and stabilizing osmolytes on protein conformational dynamics has been extensively explored due to the significant contribution of protein solvation to the stability, function, malfunction and regulation of globular proteins. We studied the effect of two nonspecific organic molecules, urea, which is a conventional denaturant, and dimethyl sulfoxide (DMSO), which is a multilateral organic solvent, on the stability and conformational dynamics of a non-inhibitory serpin, ovalbumin (OVA). A differential scanning microcalorimetry (DSC) experimental series conducted in the phosphate buffer solutions containing 0–30% of additives revealed the destabilizing impact of both urea and DMSO in a mild acidic media, manifested in the gradual decrease of thermal unfolding enthalpy and transition temperature. These findings differ from the results observed in our study of the mild alkaline DMSO buffered solutions of OVA, where the moderate stabilization of OVA was observed in presence of 5–10% of DMSO. However, the overall OVA interaction patterns with urea and DMSO are consistent with our previous findings on the stability and conformational flexibility of another model globular protein, α-chymotrypsin, in similar medium conditions. The obtained results could be explained by preferential solvation patterns. Positive preferential solvation of protein by urea in urea/water mixtures mainly weakens the hydrophobic interactions of the protein globule and eventually leads to the disruption of the tertiary structure within the whole range of urea concentrations. Alternatively, under certain experimental conditions in DMSO/water mixtures, positive preferential solvation by water molecules can be observed. We assume that the switch to the positive preferential solvation by DMSO, which is shown to have a soft maximum around 20–30% DMSO, could be shifted towards lower additive concentrations due to the intrinsic capability of ovalbumin OVA to convert into a heat-stable, yet flexible set of conformations that have increased the surface hydrophobicity, characteristic to molten-globule-like states.</p> </abstract>

Metallogenic Material Source and Genesis of the Jilinbaolige Pb-Zn-Ag Deposit, the Great Xing’an Range, China: Constraints from Mineralogical, S Isotopic, and Pb Isotopic Studies of Sulfide Ores

The Jilinbaolige Pb-Zn-Ag polymetallic deposit is located in the eastern part of Inner Mongolia and in the central-southern part of the Great Xing’an Range, in which several large-sized Pb-Zn-Ag deposits have been found. The Jilinbaolige deposit, which occurs mainly at the contact zone between Yanshanian granite intrusion and sedimentary strata, shows strong NE-to-NNE structural control. The deposit includes three ore-forming stages: (1) the arsenopyrite–pyrite–chalcopyrite–sphalerite stage, (2) the galena–sphalerite–quartz stage, and (3) the pyrite–calcite–quartz stage. In this study, we present a systematic study on the mineralogical and geochemical characteristics (including major elements, S isotopes, and Pb isotopes) of the main sulfide ore minerals in the Jilinbaolige Pb-Zn-Ag deposit in order to evaluate the metallogenic environment, ore-forming material source, and genesis of this polymetallic deposit. The sulfide typomorphic characteristics, ore fabric, and thermometry suggest that the genesis of sulfides in the deposit is closely related to magmatic-hydrothermal activity. The early stage of mineralization might have evolved from a high-temperature hydrothermal environment. The sulfur isotopic results show that the δ34S values in the Jilinbaolige deposit range from 2.3‰ to 6.1‰, with an average value of 3.98‰, indicating that the sulfur originated from magmas with both mantle and crustal components. The Pb isotopic compositions (206Pb/204Pb = 18.214–18.330, 207Pb/204Pb = 15.478–15.615, 208Pb/204Pb = 37.957–38.292, μ = 9.24–9.50, ω = 34.49–36.49) of the sulfide ores suggest that that the lead is of crust-mantle mixed origin. The comparison between the S and Pb isotopic compositions of the Jilinbaolige deposit and the polymetallic deposits from the central-southern parts of the Great Xing’an Range suggests that these deposits have a similar metallogenic source, which is closely related to the Yanshanian granite and medium-temperature hydrothermal fluids. These ore-bearing hydrothermal fluids that evolved from deep magmatic sources migrated along the contact and fracture zones and during the subsequent gradual decrease in temperature, and the metallogenic components were deposited in the relatively open fracture and fissure space. Our results provide insights for further mineral prospecting in the south-central part of the Great Xing’an Range.

Early Cretaceous climate in North Africa: Insights from the calcareous nannofossils in the atlantic passive margin of Morocco

The Early Cretaceous was a time of marked changes in global climate and carbon cycle. To reconstruct the paleoclimate in North Africa, four well-dated stratigraphic sections in the Atlantic passive margin of Morocco (Essaouira-Agadir Basin) were investigated. Calcareous nannofossil assemblages were used as indicators for medium-term climatic fluctuations. The spatiotemporal changes of key taxa, nannofossil assemblages, and the Temperature and Nutrient Indices (TI and NI) were used to reconstruct the paleoclimate. Nonmetric Multidimensional Scaling and permutational analysis of variance (PERMANOVA) indicated that only early Albian assemblage was significantly different from Barremian and Aptian ones. A steady but gradual decrease in sea surface temperature and increase in nutrients and diversity from the Barremian to the early Albian was observed. The opening of the Atlantic Ocean between Africa and South America has allowed the intrusion of cold waters and higher latitudinal taxa, where warm oligotrophic Aptian times were followed by a cool eutrophic condition in the Albian. The sea-level highstand in the Early Albian may have increased water circulation and intrusion of the upwelling induced, nutrients-rich cold-water, where surface water fertility increased significantly. Consequently, nannofossil diversity increased.

Temperature determines the shift of thermal neutral zone and influences thermogenic capacity in striped hamsters.

The thermoneutral zone (TNZ) reflects the adaptation of mammals to their natural habitat. However, it remains unclear how TNZ shifts in response to variations in ambient temperature. To test the hypothesis that ambient temperature plays a key role in determining TNZ variations between seasons, we measured metabolic rate, body temperature, and cytochrome c oxidase (COX) activity of several visceral organs in striped hamsters (Cricetulus barabensis) either acclimated to semi-natural conditions over a year, or subjected to a gradual decrease in mean temperature from 30 ± 1°C to -15 ± 1°C. The TNZ range in striped hamsters differed seasonally, with a wider TNZ and a lower lower-critical temperature in winter compared to summer. The hamsters showed a considerable leftward shift of lower-critical temperature from 30°C to 20°C after the ambient temperature of acclimation from 30°C down to -15°C, whereas the upper-critical temperature of TNZ remained fixed at 32.5°C. The resting metabolic rate in thermoneutral zone (RMRt), nonshivering thermogenesis (NST), and COX activity of brown adipose tissue, liver, skeletal muscle, brain, and kidneys, increased significantly in hamsters acclimated at lower ambient temperatures. Following acute exposure to 5°C and -15°C, hamsters acclimated to 32.5°C had significantly lower maximal NST and lower serum thyroid tri-iodothyronine (T3 ) levels compared to those kept at 23°C. These findings suggest that acclimation to the upper-critical temperature of TNZ impairs the hamsters' thermogenic capacity to cope with extreme cold temperature. Reduced ambient temperature was mainly responsible for the leftward shift of TNZ in striped hamsters, which reflects the adaptation to cold environments.

Geochemical characteristics of the Chang 7 Member in the southwestern Ordos Basin, China: the influence of sedimentary environment on the organic matter enrichment

The enrichment of organic matter is of great significance to the formation of source rocks, while its mechanism in the Chang 7 Member (Chang 71, Chang 72, and Chang 73 periods) of the southwestern Ordos Basin has not been studied in depth. Forty-eight samples obtained from Chang 7 Member were subjected to rock pyrolysis, gas chromatography-mass spectrometry (GC-MS) analysis, and determination experiments of major and trace elements to evaluate the hydrocarbon potential of the source rock, to reconstruct the sedimentary environment, and to analyze the factors of the organic matter enrichment. The results showed that the average total organic carbon (TOC) contents were 0.70%, 5.48%, and 7.70% for Chang 71, Chang 72, and Chang 73, respectively. From Chang 73 to Chang 71 period, the contents of TiO2, Al2O3, Fe2O3, and P2O5 represented a gradual increase of terrigenous input and a gradual decrease in volcanism; the Chemical Alteration Index and the Sr/Cu values reflected warm and humid paleoclimate conditions with a gradual decrease in temperature; the V/(V+Ni) and the Mo-U covariation revealed an anoxic environment with a weakened reduction; and the P/Ti-Cu/Ti model indicated a gradual decrease in paleoproductivity. The linear relationship between indicators of paleoenvironment and TOC indicated that a small amount of terrigenous input, volcanism, warm and humid climate and reducing conditions were more conducive to the enrichment of organic matter; thus we propose a Chang 73 organic matter enrichment production model and a Chang 71 organic matter enrichment preservation-dilution model.

Selective aspects of the epizootiology of Parathelohania iranica (Microsporidia: Amblyosporidae)

Parathelohania is a genus of microsporidia that preferentially attacks Anopheline mosquitoes. This study explored some selective aspects of the epizootiology of Parathelohania iranica (Microsporidia: Amblyosporidae) in its malaria mosquito host Anopheles superpictus s.l. (Diptera: Culicidae). For this study, Sar-rok Village, a place adjacent to the type locality of the parasite, located at the central western part of Iran was visited twice a month to collect host larvae from mid-summer to mid-autumn of 2017–2021. Patent infections were detected by the whitish discoloration of the involved segments. Superficially uninfected larvae were reared up to 26 days in the insectary to elucidate hidden infections. Molecular investigation and laboratory trials were conducted to evaluate the possibility of secondary infections in subsequent days. Morphological characters were used to determine the sex of larvae and adults. Data were entered in SPSS 23.0 and analyzed with relevant statistical tests as needed. In total, 584 P. iranica infected larvae of An. superpictus s.l. were collected in the study years at day zero (D0). Extended observations in the insectary revealed that 849 larvae (84.2 %), 22 dead pupae (2.2 %), and 137 emerged adults (13.6 %) were also infected. In the first two years of the study, the mean infection rate for D0 and D0 + D1-D26 infections was 6.25 % and 15.6 %, respectively. Exposure experiments indicated that subsequent infections in larvae (D1-D26) were not affected by a possible source in the accompanying field water. Patent (D0) infections were seasonal and had about a month delay compared to the general population of larvae. Concealed infections of larvae (D1-D26) were significantly more frequent in late mosquito season (P < 0.01). It is proposed that the gradual decrease of ambient temperature and the shortening of day length postpones the growth and development of P. iranica in the affected larvae. Both sexes of larvae were involved and none of them survived beyond a couple of days. The frequency of infections in adult males (5.8 %) were significantly more than females (4 %) (P = 0.02). The infections of larvae were more common in the late mosquito season, and the infections of adults were more frequent in the early mosquito season. This suggests the relative importance of vertical and horizontal routes of transmission in early and late mosquito seasons, respectively. However, age-specific data revealed that only 26 % of hidden infections of larvae (D1-D26) were stemmed from I to II age group. This implies that the vertical route may be less efficient than the horizontal route in the transmission of P. iranica to the mosquito host. These inferences should be verified with further field and laboratory investigations.

Analytical and Numerical Studies of Transient Heat Transfer in Soil for Geothermal Systems

The study of geothermal systems requires a good knowledge of heat transfers in the depth of the soil. The aim of this work is to study the distribution of temperature in the ground under the climatic conditions of Togo. The analytical and numerical solutions of unidirectional heat transfer equation assuming the soil as a semi-infinite medium are found. The analytical solution is validated by comparing the results of the present work to those found in literature. A good qualitative agreement between these results was noted. The results show that the attenuation depth decreases when the attenuation accuracy of the thermal wave increases. The analysis of the effect of moisture content indicates that the increasing in soil conductivity with moisture result in the decreasing of the attenuation depth. Soil temperature increases when increasing soil thermal diffusivity. It is found also that, soil temperatures decrease with depth and stabilize around an average value of 30°C for depths greater than about 5.8 m for all type of soil studied in the month of March which is the hottest month of the year in Togo. A gradual decrease in temperature can be seen from March to August (hot period) followed by stabilization at around 28°C with a depth of 5.8 m. The phenomenon is reversed for the months of September to February (cold period). The soil warms up slowly during the day and cools down slowly at night because of the thermal inertia of the soil. A decrease in amplitude of the thermal wave near ground surface, is observed when the Leaf Area Index (LAI) increases. However, ils influence on the stabilization depth is not very significant. Stabilization of soil temperatures in March month is observed at a depth of about 40 cm for all LAI with a value of 37°C.

Meso-structural characteristics of porous asphalt mixture based on temperature-stress coupling and its influence on aggregate damage

This paper studies the meso-structural characteristics of porous asphalt (PA) mixture and the influence of heterogeneity on the overall mechanical and thermal properties of pavement. A porous asphalt mixture model considering the temperature-stress dual-field coupling is developed. The effect of temperature stresses generated during the gradual decrease of the internal temperature of porous asphalt mixture from 25 °C to −25 °C on the micro-cracked inside the aggregate, is simulated using the finite element software. The magnitude of the temperature stress values generated inside the mixture when the internal voids of the porous asphalt mixture are filled with air and water, is analyzed. In order to analyze the tendency of expansion of micro-cracks within the aggregates in asphalt mixes under temperature stress, a macroscopic test of the maximum cooling range is carried out with Marshall specimens, and the simulation results of the finite element software are verified. The results show that when there are micro-cracked aggregates in porous asphalt mixtures, as the temperature of the asphalt mixture decreases, stress concentration occurs at the cracks of the aggregate, and the stress concentration at the end of the aggregate crack is the most obvious. The temperature stress value generated at the crack end of the damaged aggregate first reaches the aggregate crushing value. Under the same cooling amplitude, the stress value generated in the mixture when the voids of the porous asphalt mixture are filled with water is larger than that when the voids are filled with air. Finally, the obtained results have a certain reference value for the study of the damage law of porous asphalt mixture by temperature stress, when the ambient temperature decreases.

Effect of Structure and Hydrogen on the Short-Term Creep of Titanium Ti-2.9Al-4.5V-4.8Mo Alloy.

In this paper, the effect of hydrogenation, in the amount of 0.15 wt.%, on the short-term creep of a titanium Ti-2.9Al-4.5V-4.8Mo alloy in fine-grained (FG) and ultrafine-grained (UFG) states is studied at 723 K. The UFG structure was formed by the method of pressing with the change of the deformation axis and gradual temperature decrease. Creep tests are performed under conditions of uniaxial tension at a constant load for the creep rates at an interval of (10−7 ÷ 10−6) s−1. The UFG alloy’s resistance to creep under the investigated conditions is revealed to be substantially lower than in the FG state. When hydrogen presents in the alloy in a solid solution, a 1.3–2.5-fold rise in the value of the steady-state creep rate for the hydrogenated FG and UFG alloys is observed. The creep of the non-hydrogenated FG and UFG alloys is described by the creep power law. The presence of dissolved hydrogen leads to a violation of the creep power law. The values of stress sensitivity indices, steady-state creep rate, and effective creep activation energy are determined. The relationships between the hydrogenation, structure, and creep mechanisms of the alloy at the steady-state are discussed.

Effect of process parameters on the microstructure and mechanical properties of bars from Al-Cu-Mg alloy processed by multipass radial-shear rolling

The study of microstructure and mechanical properties formation of A2024 alloy obtained by the multipass radial-shear rolling (RSR) method is discussed in this article. FEM simulation was carried out that made it possible to evaluate the influence degree of rolling temperature–velocity parameters on the strain state of material. It has been found the increase in rotary velocity of rolls significantly influences on the deformation heating of bar after RSR (predominantly in its surface layer). The combination of rolling temperature–velocity conditions at selection of deformation regime has complex effect on structure and properties formation. The analysis of sizes and distribution of phase particles has shown that the rolling at lower temperatures allowed to increase the mechanical strength due to the more intensive refinement of undissolved Fe-containing phase. The gradual decrease in the rolling temperature in each pass makes possible to achieve the high strength (UTS ~ 430 MPa and YS ~ 255 MPa) while maintaining the ductility level ~ 15%, that are comparable to ones obtained at some severe plastic deformation (SPD) methods.

Effects of Growing Substrate, Mode of Nutrient Supply, and Saffron Corm Size on Flowering, Growth, Photosynthetic Competence, and Cormlet Formation in Hydroponics

Hydroponics is a promising method for cultivation of saffron (Crocus sativus). In this study, saffron corms were sprouted using a gradual decrease in air temperature, and they were cultivated hydroponically in either perlite or volcanic rock for 24 weeks. A nutrient solution was supplied using either an ebb-and-flow system or continuous immersion. First blooming was observed 29 days after transplantation. Among flowering traits, only the stigma length was significantly influenced by the type of hydroponic system. Saffron plants displayed better growth parameters, a higher photosynthetic rate and stomatal conductance (gS), as well as daughter corm (cormlet) production under the continuous immersion system, in comparison with the ebb-and-flow system. Small corms (22–25 mm diameter) did not bloom, and the emergence of flowers increased with corm size. Plant growth and photosynthetic parameters, as well as cormlet production, significantly increased with corm size. We obtained the highest stigma yield [number of flowers (1.9), stigma length (39.4 mm), stigma fresh (42.8 mg), and dry weight (5.3 mg)] and cormlet yield [number of cormlets (5.7), average corm diameter (25 mm), and fresh weight (6.4 g)] using mother corms sized ≥32 mm diameter grown hydroponically in the volcanic rock–based continuous immersion system.

Chromite Composition and Platinum-Group Element Distribution in the Proterozoic Chimalpahad Anorthosite Complex, South India: Implications for Magmatic Processes and Discrimination of Tectonic Setting

Abstract The Proterozoic Chimalpahad Anorthosite Complex (CAC) is a deformed and dismembered complex in South India comprising of anorthosite-leucogabbro-gabbro-ultramafic rocks. It is located in the Nellore-Khammam Schist Belt (NKSB) within the contact zone between the Eastern Dharwar Craton (EDC) and the Eastern Ghats Belt (EGB). The chromitites occur as small dismembered lensoidal bodies within the ultramafic rocks. Presence of micrometric inclusions of iridium-like platinum-group minerals (IPGM), such as laurite (RuS2), erlichmanite (OsS2), irarsite (IrAsS), and Ir-Os-Ru alloys, is reported for the first time in the CAC chromites. The chromite cumulates preserve magmatic character (Cr#: 0.61 to 0.77; Mg#: 0.29 to 0.55), while disseminated chromites and rims of some grains (Cr#: 0.59 to 0.89; Mg#: 0.10 to 0.25) show postmagmatic modifications. The chromites are characterised by higher Cr and Al contents and lower Fe and Ti contents. The mineral chemistry of chromites such as Cr# and Mg# contents of Al2O3 (10.05–20.07 wt.%) and TiO2 (0.1 to 0.25 wt.%) typically suggests that the CAC chromitites and their ultramafic hosts were generated from the S-undersaturated boninite melt in a magmatic arc in suprasubduction tectonic setting. A general negative slope of bulk-rock PGE distribution with upward convex pattern is observed for the CAC chromitites in the chondrite-normalized plot. These geochemical and mineral chemical characters in addition to location of the chromitites and the CAC in the tectonic zone between Eastern Dharwar Craton and Eastern Ghats Mobile Belt point towards ophiolitic affinity of the CAC chromitites. Laurite (RuS2) grains are trapped close to the cores of chromites, whereas erlichmanites (OsS2) are trapped away from the cores. Textural relations indicate primary orthomagmatic nature of laurite and Or-Ir-Ru alloys and their precipitation prior to or concomitant with chromite from an S-undersaturated melt at ~1200–1300°C and log fS2 varying between −2 and −1.3. Ru-Os disulfide and erlichmanite crystallized subsequently with a gradual decrease in temperature in the differentiating ultramafic magma. Precipitation of irarsite and base-metal sulfides can be attributed to local and rapid fluctuations of temperature, fS2, and fAs during the formation of the chromitites due to influx of fresh batch of melts or crystallization in an open magmatic system. The compositional variations of laurite-erlichmanite record heterogeneous physicochemical environment during their crystallization. In addition to zoning, preservation of IPGMs in the CAC chromites points towards fast cooling of the magma possibly associated with rapid exhumation of the chromitites and their ultramafic hosts from the roots of the subcontinental lithospheric mantle (SCLM) towards their final emplacement into the crust. Occurrence of the CAC along a linear extension with the Kondapalli Ultramafic Complex and deformed remnants of ophiolites (Kandra and Kanigiri complexes) along the eastern margin of the Eastern Dharwar Craton (EDC) bordering the Eastern Ghats Belt (EGB) indicates this zone to be a Proterozoic convergent margin.

Can slowing the rate of water temperature decline be utilized to reduce the impacts of cold water pollution from dam releases on fish physiology and performance?

Cold water pollution (CWP) is caused by releases of unseasonably cold water from large, thermally stratified dams. Rapid and prolonged decreases in water temperature can have depressive effects on the metabolism, growth and swimming performance of fish. However, it is unknown if reducing the rate of temperature decrease could mitigate these negative effects by allowing thermal acclimation/acclimatization to occur. This study investigated the rate of temperature decrease as a potential CWP mitigation strategy in juvenile Murray cod Maccullochella peelii. M. peelii were exposed to a gradual, intermediate or rapid temperature decrease from 24 to 14°C. Energetic costs, locomotor performance, growth and survival were measured to determine if the initial thermal regime affected the thermal acclimation capacity of M. peelii. Cold exposure had significant acute and lasting depressive effects regardless of the rate of temperature decrease, although M. peelii showed varying degrees of thermal compensation in swimming performance and metabolism after 8 weeks of exposure to low temperatures. The short‐term effects of CWP‐like reductions in temperature are significant, but over time M. peelii can offset some of the depressive effects of CWP through thermal plasticity. This study highlights the importance of understanding physiological responses of fish to inform management and conservation. We conclude that rate of water temperature decline cannot be used to mitigate the sublethal effects of CWP on juvenile M. peelii but may still be useful for managing the negative effects in other native Australian fish species.

How does temperature affect aggression during and after dominance hierarchy formation in Nile tilapia?

Social animals commonly establish dominance relationships by means of aggressive interaction, leading to hierarchical stability and priority of access to limited resources by high-ranked individuals. In poikilothermic animals, temperature is a major abiotic factor influencing social and non-social behaviors, including aggression. Here, we investigated the effect of cold temperature on aggression in dominance hierarchies of the commercially important tropical fish Nile tilapia (Oreochromis niloticus). Aggression components were examined in fish shoals during hierarchy formation (T1) and after hierarchy establishment (T2) under optimal (26 °C) or cold (14 °C) temperatures, and 24 h afterwards (T3) following gradual temperature increase (14–26 °C, IT treatment), decrease (26–14 °C, DT treatment) or constant optimal conditions (26 °C, CT control). During dominance hierarchy formation, fish in cold water showed reduced aggressive interactions involving lower-intensity behaviors whereas fish under warm temperature exhibited high aggression involving escalated fighting. Following temperature alterations, at T3, aggression levels increased in the IT groups, decreased in the DT groups and remained similarly high in the CT groups. However, despite the drop of temperature in the DT treatment, aggression level at T3 in cold temperature in this treatment was similar to that in the IT treatment and CT control in warm temperature. Likewise, despite the increase of temperature, aggression level in the IT treatment at T3 was lower than that observed under the same warm temperature conditions in the DT and CT groups. Our results demonstrate that in addition to the acute effect of the current temperature on aggression in dominance hierarchies, there is a significant carryover effect of prior thermal conditions under which dominance hierarchy has been formed. Thus, cold temperature can possibly be applied during hierarchy formation for mitigating adverse social effects arising from fish grouping under captive conditions.

Variscan granitic magmatism in the Western Carpathians with linkage to slab break-off

The Variscan basement within the Western Carpathian Alpine architecture generally consists of metaluminous/peraluminous tonalite/granodiorite massifs and high-grade metamorphic complexes of metapelites, metaultramafites, and metabasites with relics of eclogites. Unfortunately, the Variscan crystalline basement of the Western Carpathians is only fragmentally exposed. Therefore, the proposed geodynamic evolutionary model for the Variscan granites of the Western Carpathians is primarily based on granite data from the Malá Fatra Mts. with additional dating from the High Tatra Mts. The oldest magmatic age of 362 ± 4 Ma in the Malá Fatra horst was recorded in diatexites from a high-grade metamorphic complex, which is related to crustal anatexis during Variscan subduction. Subsequent collisional event and break-off of the subducted slab promoted exhumation of the diatexites within the high grade metamorphic complex and intrusion of 353 ± 3 Ma old Tournaisian tonalite. Intensive heat input after slab break-off from the rising asthenosphere generated melting of the lower crust and extensive calc-alkaline, Mg-rich granitic magmatism in a short time span from 347 ± 4 to 342 ± 3 Ma. These Visean granitic rocks caused thermal overprint on the roof metamorphic rocks, including diatexites and Tournaisian tonalites at ca. 348 ± 5.6 to 342 ± 3 Ma. The Visean granite formation was controlled by the mixing of hot magmas, which is indicated by the presence of composite oligoclase/andesine plagioclase with preserved labradorite cores, alkali feldspars with Na2O ≥ 2 wt%, zoned apatite, the presence of antiperthite, and quartz ocelli. Elevated contents of mantle-derived elements like V, Ni, Cr, Ba, high Sr/Y ratio of ~44, steep LREE and flat HREE segments of chondrite-normalised patterns document adakite-like feature of the investigated granitic rocks which resulted from melting of a mixed lower-crustal and mantle sources and crystallisation in the presence of garnet. Unusual abundance of Fe–Ti oxides in granodiorites with magmatic cooling temperatures of 735–756 °C supports high-T input from mantle. In the High Tatra Mts., diorite xenolith shows the age of 359.2 ± 3 Ma, and its host granodiorite the age of 350.1 ± 2.6 Ma. The diorite contains acicular zircons, which points to rapid exhumation. Stubby zircon of the host granodiorite shows regular, oscillatory zoning controlled by a gradual temperature decrease. The non-comagmatic relationships between diorite and host granodiorite are indicated also by a difference in zircon Th/U ratio, which is 0.2 for the host granodiorite, but 1.0 for the diorite on average. The presented data show that slab break-off could have been a mechanism that promoted Variscan granitic magmatism in the Western Carpathians.