Gradual Increase In Temperature Research Articles

Steady-state Calorimetry Measurement Method for Total Hemispherical Emissivity of Thermal Insulating Coating

The steady-state calorimetry technique was used to measure the total hemispherical emissivity of thermal insulating coating, after testing the the total hemispherical emissivity of thermal insulating coatings, the result showed that with the gradual increase of the test temperature, the hemispherical emissivity of heat insulation coating decreases as a whole, and with the increase of temperature, the radiation ability of heat insulation coating is reduced.

BEHAVIOR OF RARE-EARTH METALS IN HYDROMETALLURGICAL PROCESSING OF PYROCHLOR-MONAZITE-GOETHITE ORES

The article is dedicated to finding out the specific features of the behavior of rare-earth metals in hydrometallurgical processing of pyrochlore-monazite-goetite ores of the Chuktukonsky ore field is shown in the work. Chuktukonsky ore field is a potential source of rare earth metals. The mentioned ores are practically unenforceable. Hydrometallurgical methods for their complex processing were suggested. Agitational and autoclave nitric acid leaching depending on such technological parameters as temperature, HNO3 concentration, process duration, S:L ratio and the use of H2O2 were studied. The possibility of transferring manganese (that is present in a significant amount in the ore) into a nitric acid solution by hydrogen peroxide was considered. Based on the results of the conducted studies, the distribution of REM in the products of the hydrometallurgical conversion of pyrochlore-monazitegoetite ore was estimated. It was found out that incomplete opening of the ore material was observed during agitational leaching: average REM recovery into the solution is 60%. The study made it possible to solve the problem of purifying nitric acid solutions from phosphorus that hinders the subsequent extraction and separation of rare earth metal ions forming strong complexes with rare earths. Removal of phosphorus from the solution was achieved by conducting the process under pressure at elevated temperatures (200-230 0C). It was found that the optimal decomposition conditions ensuring the transfer of almost 99% of the REM into the nitric acid solution are: 25% solution of HNO3, ore size - 0.071 mm; 5% by volume H2O2; t(160 0С) = 1 h; t(230 0С) = 1 h, gradual temperature increase from 160 to 230 0С; S:L = 1:8. Autoclave nitric-acid leaching allows selecting rare earth metals from the main part of iron, phosphorus and niobium.

Prototype heat exchange and monitoring system at a municipal solid waste landfill in China

A prototype heat exchange and monitoring system was installed and operated in a newly filled municipal solid waste (MSW) landfill, located in Wuxi City, China. In this study, a test was conducted using the system to investigate the influence of heat exchange on waste temperature over three heat exchange stages. During the period of sharp increase of waste temperature, the first stage test was performed, whereas during the period of gradual increase of waste temperature, the second and third stages were performed. The results showed that (1) the waste temperature increased during the first two months after the commencement of temperature observations. This increase in temperature partially counteracted the effect of the heat exchange system on waste temperature during the first stage test. (2) During the subsequent 360 days, the waste temperature increased gradually. The influence of the heat exchange system was relatively more effective during the second and third stages than during the first stage. (3) During the test, the waste temperatures showed similar changes throughout the saturated portion of the waste, which was below the leachate level. (4) At ten days after the third heat exchange stage, the waste temperature increased gradually to the previous elevated temperature. The results of the test demonstrate that waste temperatures are mainly affected by thermal conduction in the waste mass and thermal convection in the leachate. Moreover, preliminary suggestions are provided for the installation of heat exchange pipes in landfills.

Warming and oligotrophication cause shifts in freshwater phytoplankton communities.

While there is a lot of data on interactive effects of eutrophication and warming, to date, we lack data to generate reliable predictions concerning possible effects of nutrient decrease and temperature increase on community composition and functional responses. In recent years, a wide-ranging trend of nutrient decrease (re-oligotrophication) was reported for freshwater systems. Small lakes and ponds, in particular, show rapid responses to anthropogenic pressures and became model systems to investigate single as well as synergistic effects of warming and fertilization in situ and in experiments. Therefore, we set up an experiment to investigate the single as well as the interactive effects of nutrient reduction and gradual temperature increase on a natural freshwater phytoplankton community, using an experimental indoor mesocosm setup. Biomass production initially increased with warming but decreased with nutrient depletion. If nutrient supply was constant, biomass increased further, especially under warming conditions. Under low nutrient supply, we found a sharp transition from initially positive effects of warming to negative effects when resources became scarce. Warming reduced phytoplankton richness and evenness, whereas nutrient reduction at ambient temperature had positive effects on diversity. Our results indicate that temperature effects on freshwater systems will be altered by nutrient availability. These interactive effects of energy increase and resource decrease have major impacts on biodiversity and ecosystem function and thus need to be considered in environmental management plans.

Microbial community adaptability to altered temperature conditions determines the potential for process optimisation in biogas production

The operating temperature in anaerobic digestion strongly affects biogas yield, process stability and the potential for process optimisation. However, many questions remain on how to manage process operation for optimized microbial community adaptation following temperature changes. A long-term anaerobic digestion experiment was conducted to determine temperature-related issues in operative full-scale biogas plants and to evaluate optimisation potential and links to microbial community structure and responses. Four digesters fed household and slaughterhouse waste were operated in sets of two, at 37 °C or 52 °C, followed by a gradual increase or decrease in temperature in one digester in each set. Stability and flexibility of the digesters were then assessed by step-wise increases in organic loading rate (OLR) from 3 to 7 g VS/(L day), concurrently with decreased hydraulic retention time from 33–40 days to 14–17 days. Transition of operating temperature regime was possible, irrespective of starting temperature. However, slight temporary instability occurred at 42–44 °C and for the thermophilic to mesophilic process a period of adaptation was required to overcome this imbalance. The digesters with constant temperature and the mesophilic-to-thermophilic digester remained stable at the target OLR, demonstrating considerable optimisation potential for the large-scale biogas plants investigated. However, the digester that was changed from thermophilic to mesophilic conditions failed at 6 g VS/(L day). Comparisons of biological and chemical parameters suggested that this failure was caused by a lag in resilience of the acetate and propionate-degrading populations inherited from the community shaped by initial operation in thermophilic conditions. Taken together, these results demonstrate that the existing biogas plants are operating below capacity and that, depending on temperature, the annual energy production could be increased from 26–28 to 59–65 GWh through increasing OLR from 3 to 7 g VS/(L day). However, the results also highlight the importance of careful management and the risks when applying strategies not fully evaluated for the specific system. To our knowledge, this is the first study to demonstrate process performance, optimisation potential and microbial community adaptability to temperature changes in continuously fed anaerobic digesters under both increasing and decreasing operating temperature. The results could be used to guide operation management under temperature changes and increasing OLR in industrial-scale biogas processes.

Natural variation at qHd1 affects heading date acceleration at high temperatures with pleiotropism for yield traits in rice

BackgroundRice is highly sensitive to temperature fluctuations. Recently, the frequent occurrence of high temperature stress has heavily influenced rice production. Proper heading date in specific environmental conditions could ensure high grain yield. Rice heading greatly depends on the accurate measurement of environmental changes, particularly in day length and temperature. In contrary to the detailed understanding of the photoperiod pathway, little has been known about how temperature regulates the genetic control of rice heading.ResultsNear isogenic lines that were segregated for qHd1, were developed from a cross between indica rice varieties Zhenshan 97 (ZS97) and Milyang 46 (MY46). Using a five sowing-date experiment in the paddy field, we observed the involvement of qHd1 in temperature responses. With the gradual increase of temperature from Trial I to V, heading date of MY46 homozygotes continued to decrease for about 5 d per trial from 76 to 58 d, while that of ZS97 homozygotes was promoted at the same rate from Trial I to III and then stabilized at 69 d. This thermal response was confirmed in a temperature-gradient experiment conducted in the phytotron. It is also found that tolerance of the ZS97 allele to heading acceleration at high temperature was associated with higher grain weight that resulted in higher grain yield. Then, by qRT-PCR and RNA-seq, we found the pathway OsMADS51-Ehd1-RFT1/Hd3a underlying the qHd1-mediated floral response to temperature. By sequence comparison, OsMADS51 for qHd1 displayed a 9.5-kb insertion in the 1st intron of the ZS97 allele compared to the MY46 allele. Furthermore, this large insertion is commonly found in major early-season indica rice varieties, but not in the middle- and late-season ones, which corresponds to the requirement for high-temperature tolerance during the heading and grain-filling stages of early-season rice.ConclusionsBeneficial alleles at qHd1 confer tolerance to high temperatures at the heading and grain-filling stages, playing a significant role in the eco-geographical adaptation of early-season indica rice during modern breeding. These results, together with the underlying OsMADS51-Ehd1-RFT1/Hd3a floral pathway, provide valuable information for better understanding the molecular mechanism of temperature responsive regulation of heading date and yield traits in rice.

Minimal Heating at the Skin Surface During Transcranial Direct Current Stimulation

To assess if transcranial direct current stimulation (tDCS) produces a temperature change at the skin surface, if any change is stimulation polarity (anode or cathode) specific, and the contribution of passive heating (joule heat) or blood flow on such change. Temperature differences (ΔTs) in an agar phantom study and an in vivo study (forearm stimulation) including 20 volunteers with both experimental measures and finite element method (FEM) multiphysics prediction (current flow and bioheat) models of skin comprising three tissue layers (epidermis, dermis, and subcutaneous layer with blood perfusion) or of the phantom for active stimulation and control cases were compared. Temperature was measured during pre, post, and stimulation phases for both phantom and subject's forearms using thermocouples. In the phantom, ΔT under both anode and cathode, compared to control, was not significantly different and less than 0.1°C. Stimulation of subjects resulted in a gradual increase in temperature under both anode and cathode electrodes, compared to control (at t = 20 min: ΔTanode = 0.9°C, ΔTcathode = 1.1°C, ΔTcontrol = 0.05°C). The FEM phantom model predicted comparable maximum ΔT of 0.27°C and 0.28°C (at t = 20 min) for the control and anode/cathode cases, respectively. The FEM skin model predicted a maximum ΔT at t = 20 min of 0.98°C for control and 1.36°C under anode/cathode electrodes. Taken together, our results indicate a moderate and nonhazardous increase in temperature at the skin surface during 2 mA tDCS that is independent of polarity, and results from stimulation induced blood flow rather than joule heat.

Combined cycle schemes coupled with a Very High Temperature gas-cooled reactor

With gradual increase in reactor outlet temperature, the efficient power conversion technology has become one of developing trends of (very) high temperature gas-cooled reactors (HTGRs/VHTRs). In this paper, physical and mathematical models of two combined cycle schemes coupled with the VHTR, Reheated Combined Cycle (RCC) and Regenerative-Reheated Combined Cycle (RRCC), are established. Their topping cycle is a no precooling and no intercooling Brayton cycle, and their bottoming cycle is a supercritical Rankine cycle. The effects and mechanism of key parameters were analyzed. Based on parameter analysis, two schemes were compared within the temperature range of the VHTRs (ROT 950–1200 °C). The analysis shows that, for the combined cycle of the VHTR, by adding a recuperator, can further utilize the helium turbine exhaust heat, then to improve the cycle efficiency. When the ROT is 1050 °C, the cycle efficiency of the RRCC (recuperator's effectiveness 0.4）is 56.4%, which is 2.18% higher than that of the RCC. But because of the regenerative process, the reactor inlet temperature (RIT) of the RRCC is higher than 490 °C, additional reactor pressure vessel (RPV) cooling system is necessary, and it increases the system complexity and reduce the cycle's efficiency. The RIT of the RCC can be controlled below 490 °C, no RPV cooling system is required. Amongst the main parameters, the recuperator's effectiveness and compression ratio are the most important factor affecting the cycle efficiency of the VHTR. The cycle efficiency can be increased by 0.61% when the recuperator's effectiveness is increased by 0.1. The main factors that limit the increase of the recuperator's effectiveness are the RIT and the system flow resistance. When the average compression ratio increases by 0.1, the combined cycle efficiency increases by 0.33% (RCC) and 0.373% (RRCC). The main factors that limit the increase of compression ratio are the manufacturing capacity of magnetic bearings, turbines and compressors. These results provide insights on the combined cycle of the VHTRs, and reveal the effects of key parameters on performance of these cycles. It could be helpful to understand and develop a combined cycle coupled with a VHTR in the future.

Structural and magnetic properties of ytterbium substituted spinel ferrites

Chemical co-precipitation route adopted to synthesize the magnetic materials. In the present work, iron is replaced by ytterbium ion in manganese-based spinel ferrites. The yield chemically represented by MnYb x Fe2−xO4 (x = 0.00, 0.025, 0.05, 0.075, 0.10) and its structural, magnetic and electrical properties were observed. The cubic structure of spinel ferrites was confirmed by X-ray diffraction analysis. Spherically shaped grains were perceived in SEM pictures and size lessened with the growth of ytterbium concentration. SEM profile also shows little irregularity in spherical particles. The substitution of ytterbium (Yb) results in the enhancement of electrical resistivity. The resistivity was reduced with the gradual increase in temperature from 303 to 693 K. The trend of activation energy was found to be similar to that of room temperature resistivity. The coercivity of samples was raised with Yb-ion substitution while saturation magnetization and remanence reduced.

Adaptation strategies of yak to seasonally driven environmental temperatures in its natural habitat.

The gradual increase of ambient temperature (TA) at high altitude can cause heat stress as an effect of climate change and may shift the traditional habitat of yak to further higher altitude. Therefore, an attempt has been made in this study to evaluate the thermo-adaptability of yaks to different seasons at high altitude. The adaptive capabilities of yaks were assessed based on different heat tolerance tests in relation to changes in rectal temperature (RT; °F), respiration rate (RR; breaths/min), pulse rate (PR; beats/min), and plasma heat shock protein (HSP) profile. The experiment was conducted in 24 yaks, divided into three groups based on age as calf (n = 8), adult (n = 8), and lactating cow (n = 8). Thermal adaptability was determined by temperature humidity index (THI), dairy search index (DSI), and Benezra's thermal comfort index (BTCI) along with HSP70 profile. The THI was higher (P < 0.01) in summer than winter which increased from lowest (40.87) to highest (61.03) in summer by 20 points, where yaks were under heat load beyond THI 52. The RT (100.09 ± 0.18°F), RR (21.76 ± 0.18), and PR (59.78 ± 0.32) increased by 23-35%, and this was correlated to the higher values of DSI exceeding 1 in calves (1.35 ± 0.03), lactating cows (1.29 ± 0.04), and adults (1.23 ± 0.32) during summer in comparison to winter (0.98 ± 0.02). The BTCI also showed values greater (P < 0.01) than 2 in calves (3.47 ± 0.27), lactating cows (3.23 ± 0.28), and adults (2.98 ± 0.29) which reflected 49-75% increase in rectal temperature and respiration rate during summer. Further, heat stress was substantiated by threefold higher (P < 0.01) level of plasma HSP70 in calves (189.61 ± 3.90pg/ml) followed by lactating cows (168.62 ± 3.03pg/ml) and adults (155.33 ± 2.30pg/ml) against the winter average of 87.92 ± 3.19pg/ml. Present results revealed that yaks were experiencing heat stress in summer at an altitude of 3000m above sea level and calves were more prone to heat stress followed by lactating cows and adults.

SOME FEATURES IN INTERACTIONS BETWEEN SYMBIONTS AND THEIR HOSTS AS EXEMPLIFIED BY STARFISH CULCITA NOVAEGUINEAE AND GASTROPODS STILIFER VARIABILIS

During the observations of echinoderms in the natural conditions (South China Sea, Nha Trang Bay), a peculiar phenomenon of the rejection of symbiotic gastropods by host-starfish tissues was discovered. Later on, laboratory experiments were carried out in aquariums in order to find the cause of this phenomenon. Starfish Culcita novaeguin eae bearing gastropods Stilifer variabilis were kept for 10 days in aquariums with no aeration and a gradual increase in water temperature. as a result, an unusual behavior of gallforming symbiotic gastropods was revealed: the apex of the shell began to stick more out of the surface of the host’s body, and in some cases sudden ejection of egg capsules by the symbionts was noted. In contract to the natural conditions, however, the symbionts neither died nor were totally rejected by the host’s tissues. There are plans to continue aquarium-based laboratory experiments with a larger selection of starfish and their sym bionts, and to analyze various abiotic environmental factors (not only the temperature regime and the oxygen content in the water).

English

This paper treats the impacts of climate change on peanut yield in Ziguinchor (Southwest of Senegal) during the near future (2021 to 2050) and the far future (2071 to 2100). The Decision Support System for Agrotechnology Transfer (DSSAT) crop model was run using daily weather data (maximum and minimum surface temperature, rainfall and solar radiation) of four (4) regional climate models (RCMs) of the Coordinated Regional Climate Downscaling Experiment (CORDEX). Two climate change scenarios (RCP4.5 and RCP8.5) are used to assess the climate change impact on peanut yield. First of all, the DSSAT crop model is calibrated and validated for peanut using relevant observed data: peanut yield and meteorological data. Compared to the reference period (1976 to 2005), the RCMs exhibit some disparities in the projected rainfall during the near and the far future. The ensemble mean of the models (Ens/RCMs) predict a strong decrease of rainfall under the RCP4.5 scenario and a slight decrease under the RCP8.5 scenario during both periods. A gradual increase in mean temperature is predicted by all models. However, this increase is stronger for the RCP8.5 scenario. Analysis of the yield change during the near future shows a decrease for all RCMs except RACMO22T model under the two considered scenarios. During the far future, all RCMs predict a decrease of the peanut yield. Moreover, this decrease is stronger for the RCP8.5 scenario. These results indicated that the peanut crop could be negatively affected by the climate change and adaptation strategies are needed to protect this sector. Key words: Climate change, Regional Climate Models, Coordinated Regional Climate Downscaling Experiment (CORDEX), Decision Support System for Agrotechnology Transfer (DSSAT), peanut.

Residual heat generated during laser processing of CFRP with picosecond laser pulses

Abstract One of the major reasons for the formation of a heat-affected zone during laser processing of carbon fiber-reinforced plastics (CFRP) with repetitive picosecond (ps) laser pulses is heat accumulation. A fraction of every laser pulse is left as what we termed residual heat in the material also after the completed ablation process and leads to a gradual temperature increase in the processed workpiece. If the time between two consecutive pulses is too short to allow for a sufficient cooling of the material in the interaction zone, the resulting temperature can finally exceed a critical temperature and lead to the formation of a heat-affected zone. This accumulation effect depends on the amount of energy per laser pulse that is left in the material as residual heat. Which fraction of the incident pulse energy is left as residual heat in the workpiece depends on the laser and process parameters, the material properties, and the geometry of the interaction zone, but the influence of the individual quantities at the present state of knowledge is not known precisely due to the lack of comprehensive theoretical models. With the present study, we, therefore, experimentally determined the amount of residual heat by means of calorimetry. We investigated the dependence of the residual heat on the fluence, the pulse overlap, and the depth of laser-generated grooves in CRFP. As expected, the residual heat was found to increase with increasing groove depth. This increase occurs due to an indirect heating of the kerf walls by the ablation plasma and the change in the absorbed laser fluence caused by the altered geometry of the generated structures.

Adaptation to Heat and Cold in the Context of a Changing Climate: A Multi-Country Analysis

Background/Aim: The net impact of global warming will depend on the extent to which adaptation overcomes the effect of gradual changes in temperature. Disentangling the two processes is critical to provide accurate projections of future temperature-related impacts under climate change scenarios. We present evidence from a multi-country investigation that assessed temporal trends in mortality attributed to both heat and cold, and adaptation. Methods: We collected data from 305 locations in 10 countries between 1985 and 2012. Temporal trends in country-specific attributable mortality fractions (AF) for heat/cold (temperatures above/below minimum mortality temperature) were estimated using a two-stage time series design with time-varying distributed lag non-linear models and multivariate meta-analysis. To disentangle the contribution of adaptation from changes in attributable mortality due to gradual increases in temperature, we compared yearly AF with those predicted assuming either temperature distribution or exposure-response relationships as constant across the study period, respectively. Results: Heat-AF decreased in all countries except Australia and United Kingdom, from 0.45-1.39% in the first to 0.15-0.93% in the last 5-year periods, respectively. Different patterns were found for cold, with ranges from 5.56-15.43% to 2.17-8.54%, showing either decreasing (Japan, Spain, Australia, Ireland), increasing (US), or stable trends (Canada, South Korea, United Kingdom). We found inconsistent patterns in Brazil and Switzerland and a null heat-impact in Ireland. Long-term trends were mostly captured by temporal variation in exposure-response associations (interpreted as adaptation), while year-to-year fluctuations were driven by changes in temperature distribution. Conclusions: Our findings indicate that heat-mortality impacts decreased in most countries consistent with previous studies, whereas cold-mortality exhibited heterogeneous trends. In addition, the pace of adaptation has been faster than the observed warming, suggesting there is scope for the implementation of effective public health policies under climate change. Further investigations should focus on identification of the factors responsible for these adaptation trends.

The risk of tardive frost damage in French vineyards in a changing climate

Tardive frosts, i.e. frost events occurring after grapevine budburst, are a significant risk for viticultural practices, which have recently caused substantial yield losses over different winegrowing regions of France, e.g. in 2016 and 2017. So far, it is unclear whether the frequency of late frosts events is destined to increase or decrease under future climatic conditions. Here, we assess the risk of tardive frosts for the French vineyards throughout the 21st century by analyzing temperature projections from eight climate models and their statistical regional downscaling. Our approach consists in comparing the statistical occurrences of the last frost (day of the year) and the characteristic budburst date for nine grapevine varieties as simulated by three different phenological models. Climate models qualitatively agree in projecting a gradual increase in temperature all over the France, which generally produces both an earlier characteristic last frost day and an earlier characteristic budburst date. However, the latter notably depends on the specific phenological model, implying a large uncertainty in assessing the risk exposure. Overall, we identified Alsace, Burgundy and Champagne as the most vulnerable regions, where the probability of tardive frost is projected to significantly increase throughout the 21st century for two out of three phenological models. The third phenological model produces opposite results, but the comparison between simulated budburst dates and observed records over the last 60 years suggests its lower reliability. Nevertheless, for a more trustworthy risk assessment, the validity of the budburst models should be accurately tested also for warmer climate conditions, in order to narrow down the associated large uncertainty.

Nanoscale defolding influence of polypeptides in the charge-transfer process through an organic-inorganic nanohybrid system.

A biologically important polypeptide [with an alternate sequence of alanine (ALA) and 2-aminobutyric acid (AiB)] is used as a linker molecule to investigate the charge-transfer phenomenon between CdSe nanoparticle (NP) (diameter ∼6-7 nm) assemblies and gold (Au) substrates. The (ALA-AiB)n polypeptides, with varying chain lengths n = 5, 8, 11, were attached to the surface to form self-assembled monolayers (SAMs) through a thiol group located either at the N-terminal or C-terminal of the sequence. Temperature dependent photoluminescence (PL) spectra showed anomalous behavior in the quenching regime of CdSe NPs in the 237 K to 290 K region. In principle, the fluorescence intensity of any fluorophore decreases with a gradual increase in temperature, due to dominating non-radiative relaxation over radiative relaxation. PL spectral intensity follows this general trend from 77 K to 237 K for all chain lengths. For chain length n > 5 (n = 5 showed a kink, but the extent of the kink is negligible in comparison with n > 5) polypeptide-based monolayers, there is a sudden increase in fluorescence intensity above 237 K. This sudden increase is probed using molecular dynamics simulations which reveals that this unprecedented behavior arises due to interchain polypeptide interactions. An insertion of an alkyl chain with an almost similar length of peptide along with polypeptide (in a 3 : 1 ratio, in terms of concentration) diminishes the interchain polypeptide hydrogen-bonding interactions and manifests the normal trend of PL spectra.

Reproductive gene expression in a coral reef fish exposed to increasing temperature across generations.

Reproduction in marine fish is generally tightly linked with water temperature. Consequently, when adults are exposed to projected future ocean temperatures, reproductive output of many species declines precipitously. Recent research has shown that in the common reef fish, Acanthochromis polyacanthus, step-wise exposure to higher temperatures over two generations (parents: +1.5°C, offspring: +3.0°C) can improve reproductive output in the F2 generation compared to F2 fish that have experienced the same high temperatures over two generations (F1 parents: +3.0°C, F2 offspring: +3.0°C). To investigate how a step-wise increase in temperature between generations improved reproductive capacity, we tested the expression of well-known teleost reproductive genes in the brain and gonads of F2 fish using quantitative reverse transcription PCR and compared it among control (+0.0°C for two generations), developmental (+3.0°C in second generation only), step (+1.5°C in first generation and +3.0°C in second generation), and transgenerational (+3.0°C for two generations) treatments. We found that levels of gonadotropin receptor gene expression (Fshr and Lhcgr) in the testes were reduced in developmental and transgenerational temperature treatments, but were similar to control levels in the step treatment. This suggests Fshr and Lhcgr may be involved in regulating male reproductive capacity in A. polyacanthus. In addition, lower Fshb expression in the brain of females in all temperature treatments compared to control, suggests that Fshb expression, which is involved in vitellogenesis, is sensitive to high temperatures. Our results help elucidate key genes that facilitate successful reproduction in reef fishes when they experience a gradual increase in temperature across generations consistent with the trajectory of climate change.

Environmental changes around the Oligocene/Miocene boundary in the Limagne graben, Massif Central, France

Continental environments are very sensitive to climatic variations. A unique opportunity to study the climate changes around the Oligocene/Miocene boundary is offered by the Limagne graben Basin (France) where this stage boundary is well constrained by fossils. Indeed, some localities of the Limagne Graben Basin are so rich in mammal remains that they have become a European reference for mammal biostratigraphy. The dominant sedimentary facies of the lacustrine deposits in the northern part of the Limagne Graben Basin are composed of poorly cemented marls and calcarenites containing various plants and animals remains (e.g.algae, fish bones and teeth, gastropods, ostracods, mammals, birds and reptiles remains) associated with stromatolites. Mammal remains, well described in this area from the literature, were used to constrain the chronostratigraphic context of this lacustrine basin, with refinement thanks to new carbon and oxygen isotope measurements, palynological and sedimentological data. In this work, the available information obtained from a classical paleoecological study has been refined by new carbon and oxygen isotope analyses of carbonates and fish teeth retrieved from the washed sediment residues. The results of this study confirm that the Oligocene/Miocene boundary in Europe was a general period of aridity, associated with a cooler climate, which could be the cause of the decline in mammal paleodiversity observed during this period. The gradual evolution from brackish to fresh waters is indicated by the presence of ostracods and gastropods, and the major development of caddisflies. This period is associated to humid climatic conditions while a gradual increase in temperature took place throughout the second part of the Aquitanian. These environmental changes were driven by strong variations of temperatures and a contrasted seasonality.

Effects of Preheating Electrolyte in Micro ECDM Process

ECDM is a hybrid machining process with enormous potential in machining both conducting & non conducting materials. Present paper focuses on determining the effects of preheating the electrolyte in ECDM process experimentally. Through detailed experimental study, it was found that temperature of electrolyte plays a major role in Material Removal Rate (MRR) and Heat Affected Zone (HAZ) formation.In this work, NaOH was chosen as the electrolyte and was heated to various temperature ranges. Micro features were then machined on the Poly Propylene (PP) work piece and the effect on micro structure formation was analysed. It was found that higher temperature produces spark reduction but causes an increase in heat affected zones in PP. SEM images were used to study the micro features generated on PP. An experimental plan based on Taguchi’s L32orthogonal array was chosen. The machining rate was found to improve with gradual increase in temperature. Beyond certain level, temperature was found to have adverse effects on the properties of PP. An optimum temperature range was calculated in order to carry out the machining at a faster rate without destruction of micro-features.

Effect of environmental conditions and management strategies in commercial aquaculture systems on juvenile milkfish (Chanos chanos) quantified by scale cortisol

Event Abstract Back to Event Effect of environmental conditions and management strategies in commercial aquaculture systems on juvenile milkfish (Chanos chanos) quantified by scale cortisol Inken Hanke1, 2*, Bart Ampe3, 4, Andreas Kunzmann1, Astrid Gärdes1 and Johan Aerts2, 3 1 Leibniz Centre for Tropical Marine Research (LG), Germany 2 Ghent University, Faculty of Pharmaceutical Sciences, Belgium 3 Institute for Agricultural and Fisheries Research (ILVO), Belgium 4 Institute for Agricultural and Fisheries Research (ILVO), Animal Sciences Unit, Belgium The global intensification of commercial aquaculture production has become an increasing threat for the performance and growth of cultured fish. Besides suboptimal management strategies, such as high stocking densities, fish have to cope with changing environmental conditions, as commonly encountered in outdoor systems. In a previous experimental study, we observed a significant increase in stress response mediated by the hypothalamic-pituitary-interrenal (HPI) axis and quantified by ontogenetic and regenerated scale cortisol, when exposing juvenile milkfish to a single stimulus of minute and gradual temperature increase (manuscript currently under review). In this study, we evaluated for the first time the stress response of juvenile milkfish in a commercial aquaculture setting by using ontogenetic scale cortisol. Fish were collected from four different cages, from the beginning of the mariculture park, nearby channel inlet to the open ocean (F1, F2), along the Guiguiwanen Channel in mid (F3) and the end region (F4) of the mariculture park in Bolinao (Philippines). Ontogenetic scales of 6 fish per cage/sampling point were analyzed for cortisol and environmental conditions were monitored after 86 (D86) and 100 days (D100) of culture time. For all stations, scale cortisol was significantly higher at D100. Hereby, significant differences in scale cortisol levels were observed between stations per sampling as well as in daily incorporation of scale cortisol. Highest scale cortisol levels were recorded at F4, where fish were kept at the highest stock density. On the other hand, fish from F1 exhibited the highest rate of daily incorporated scale cortisol. Subsequently, when taking into account the existing culture conditions, scale cortisol levels showed that management strategy as well as location of the cage in the mariculture park/along the channel had a significant effect on the stress level of fish. This is to our knowledge the first study on chronic stress in milkfish. Hereby, the use of scale cortisol was shown to be effective, making it a powerful tool in optimizing aquaculture systems as well as in monitoring gradual climate changes in wild stock. Keywords: Scale cortisol, stress response, Aquaculture, temperature, Milkfish Conference: IMMR'18 | International Meeting on Marine Research 2018, Peniche, Portugal, 5 Jul - 6 Jul, 2018. Presentation Type: Oral Presentation Topic: Aquaculture Citation: Hanke I, Ampe B, Kunzmann A, Gärdes A and Aerts J (2019). Effect of environmental conditions and management strategies in commercial aquaculture systems on juvenile milkfish (Chanos chanos) quantified by scale cortisol. Front. Mar. Sci. Conference Abstract: IMMR'18 | International Meeting on Marine Research 2018. doi: 10.3389/conf.FMARS.2018.06.00081 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 23 Apr 2018; Published Online: 07 Jan 2019. * Correspondence: Ms. Inken Hanke, Leibniz Centre for Tropical Marine Research (LG), Bremen, Germany, Inken.Hanke@leibniz-zmt.de Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Inken Hanke Bart Ampe Andreas Kunzmann Astrid Gärdes Johan Aerts Google Inken Hanke Bart Ampe Andreas Kunzmann Astrid Gärdes Johan Aerts Google Scholar Inken Hanke Bart Ampe Andreas Kunzmann Astrid Gärdes Johan Aerts PubMed Inken Hanke Bart Ampe Andreas Kunzmann Astrid Gärdes Johan Aerts Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.