Central Temperature Research Articles

A Physics-Informed Auto-Learning Framework for Developing Stochastic Conceptual Models for ENSO Diversity

Abstract Understanding El Niño–Southern Oscillation (ENSO) dynamics has tremendously improved over the past few decades. The ENSO diversity in spatial pattern, peak intensity, and temporal evolution is, however, still poorly represented in conceptual ENSO models. In this paper, a physics-informed auto-learning framework is applied to derive ENSO stochastic conceptual models with varying degrees of freedom. The framework is computationally efficient and easy to apply. Once the state vector of the target model is set, causal inference is exploited to build the right-hand side of the equations based on a mathematical function library. Fundamentally different from standard nonlinear regression, the auto-learning framework provides a parsimonious model by retaining only terms that improve the dynamical consistency with observations. It can also identify crucial latent variables and provide physical explanations. This methodology successfully reconstructs the equations of a realistic six-dimensional reference ENSO model based on the recharge oscillator theory from its data. A hierarchy of lower-dimensional models is derived, and their representation of ENSO (including its diversity) is systematically assessed. The minimum model that represents ENSO diversity is four-dimensional, with three interannual variables describing the western Pacific thermocline depth, the eastern and central Pacific sea surface temperatures (SSTs), and one intraseasonal variable for westerly wind events. Without the intraseasonal variable, the resulting three-dimensional model underestimates extreme events and is too regular. A limited number of weak nonlinearities in the model are essential in reproducing the observed extreme El Niño events and the observed nonlinear relationship between eastern and western Pacific SSTs. Significance Statement This study develops a physics-informed auto-learning approach to improve the modeling and understanding of El Niño–Southern Oscillation (ENSO), a major climate phenomenon influencing global weather and climate. The auto-learning framework explores the causality between key processes to systematically produce stochastic conceptual models with different climate factors that simulate the diversity of observed ENSO events. The key finding is that the minimal model for characterizing the ENSO diversity (with the least number of climate factors) is a four-variable model capturing thermocline depth, sea surface temperatures, and wind bursts that can reproduce intensity and spatial pattern variation. This advancement provides an interpretable tool to identify the minimum sufficient processes governing ENSO behavior for improved predictability.

Thermal-hydraulic and safety analysis of alternative ceramic fuels in next generation of VVER-1000 reactor

Abstract The main aim of this study is the thermohydraulic and safety analysis of alternative UN and UC ceramic fuels in the next generation of VVER-1000/V446 reactor core. One of the advantages of these alternative fuels is their higher thermal conductivity and density relative to the UO2 conventional fuels. Thermohydraulic analysis has been performed under full power conditions. Also, the safety evaluation of alternative ceramic fuels has been researched by the Rod Ejection Accident (REA) scenario. RELAP5 Mod3.2 code is used for thermo-hydraulic analysis in both steady state and transient state in VVER-1000/V446 reactor. In addition, calculations of the fuel center temperature in mean and hot channels for steady state, the temperature of the hottest rod in the fuel assembly, the radial distribution of fuel temperature for both channels, and the maximum clad temperature during the reactivity injection have been performed. The results showed that in the steady state with full power, the fuel centreline temperature in UO2 is about twice the corresponding values for UN and UC alternative fuels which is very attractive from a safety point of view. In general, due to the large difference between the hot spot point and the melting point in alternative fuels, the thermal power and safety factors can be significantly increased in the next generation of VVER-1000/V446 reactors.

Study on the anti-ablation behavior of (Ti,W)3AlC2 under oxyacetylene flame above 2500 K

To evaluate the reliability of (Ti,W)3AlC2 in aerospace ablation conditions, the ablation behavior of (Ti,W)3AlC2 ceramic is investigated by using oxyacetylene flame above 2550 K. Results show a four-stage process exists with the formation of TiO2-Al2TiO5-Al2O3. Once the central ablation temperature exceeds 2350 K, the innermost Al2O3 layer melts and collapses, exposing the decomposed TiCx-Al matrix directly to the flame with rapid oxidation and a remarkable increase of the linear ablation rate. The melt finally flows out with the flame from the ablation center and solidifies into a stripe-like TiO2-Al2TiO5 eutectic oxide above the protective oxide layer. The refractory W particles detected in the eutectic TiO2-Al2TiO5 may retard the flowing rate of the fluid by increasing its viscosity, resulting in a better ablation resistance performance in the later period of the ablation process, making the linear ablation rate lower from 10.30 μm/s of Ti3AlC2 to 9.01 μm/s of (Ti,W)3AlC2.

2-D modeling of torrefaction of a large biomass particle: effect of L/D ratio, internal convection and shrinkage

ABSTRACT Torrefaction of a large biomass particle was investigated using a transient 2-D model, including primary and secondary reactions kinetics and heat transfer, internal convection, and shrinkage. The model predictions matched with the experimental results within +2%. Spatial and temporal distributions of temperature, residual mass fraction, velocity, and pressure inside the particle and the effect of reactor temperature, residence time, particle size, and shrinkage on the torrefaction behaviour were investigated. Evolution of moisture, volatiles and gases due to drying and torrefaction increase the pressure inside the particle, setting up a velocity field and internal convection. Average velocity and pressure reached a peak during the initial drying period due to moisture evolution, and a subsequent second peak due to the formation of volatiles and gases by torrefaction at a reactor temperature > 493 K. Internal convection influenced torrefaction significantly but the particle shrinkage did not impact it appreciably. The degree of overshoot of the particle center temperature above the reactor temperature increased with the reactor temperature and the particle diameter. Simulations suggest that a reactor temperature of 550 K and residence of about 30 min would be suitable for torrefaction of a particle with L = D = 25.4 mm.

First map of D2H+ emission revealing the true centre of a prestellar core: Further insights into deuterium chemistry

Context. IRAS 16293E is a rare case of a prestellar core being subjected to the effects of at least one outflow. Aims. We want to disentangle the actual structure of the core from the outflow impact and evaluate the evolutionary stage of the core. Methods. Prestellar cores being cold and depleted, the best tracers of their central regions are the two isotopologues of the trihydrogen cation that are observable from the ground: ortho-H2D+ and para-D2H+. We used the Atacama Pathfinder EXperiment (APEX) telescope to map the para-D2H+ emission in IRAS 16293E and collected James Clerk Maxwell Telescope (JCMT) archival data of ortho-H2D+. We compared their emission to that of other tracers, including dust emission, and analysed their abundance with the help of a 1D radiative transfer tool. The ratio of the abundances of ortho-H2D+ to para-D2H+ can be used to estimate the stage of the chemical evolution of the core. Results. We have obtained the first complete map of para-D2H+ emission in a prestellar core. We compare it to a map of ortho-H2D+ and show their partial anti-correlation. This reveals a strongly evolved core with a para-D2H+/ortho-H2D+ abundance ratio towards the centre for which we obtain a conservative lower limit from 3.9 (at 12 K) to 8.3 (at 8 K), while the high extinction of the core is indicative of a central temperature below 10 K. This ratio is higher than predicted by the known chemical models found in the literature. Para-D2H+ (and indirectly ortho-H2D+) is the only species that reveals the true centre of this core, while the emission of other molecular tracers and dust are biased by the temperature structure that results from the impact of the outflow. Conclusions. This study is an invitation to reconsider the analysis of previous observations of this source and possibly questions the validity of the deuteration chemical models or of the reaction and inelastic collisional rate coefficients of the H+3 isotopologue family. This could impact the deuteration clock predictions for all sources.

Effects of asymmetric rough boundaries on turbulent Rayleigh–Bénard convection

We report on an experimental study of turbulent Rayleigh–Bénard convection with asymmetric top and bottom plates. The plates are covered with pyramid-shaped roughness elements whose aspect ratios are $\lambda =1$ or $\lambda =4$ . In the low-Rayleigh-number regime ( $Ra<1.9\times 10^9$ ), the heat transport efficiencies in the asymmetric cells, characterized by the Nusselt number, are smaller than those measured in a symmetric $\lambda = 1$ cell and are greater than those for a symmetric $\lambda = 4$ cell, whereas in the high-Rayleigh-number regime ( $Ra>1.9\times 10^9$ ), the Nusselt numbers of the asymmetric cells are, in turn, greater than those for the symmetric cell with $\lambda = 1$ and smaller than those for the symmetric cell with $\lambda = 4$ . In addition, the heat transports of individual plates are studied based on the temperature drops across both halves of the cell. In the low- $Ra$ regime, the $\lambda =1$ plate shows higher heat transfer than the $\lambda =4$ plate, while for the high- $Ra$ regime, the $\lambda =4$ plate shows a higher heat transport ability. In both regimes, the individual Nusselt number of the plate with lower heat transfer is insensitive to the topology of the other plate. Besides, it is found that the symmetry of the centre temperature distribution is robust to the symmetry breaking of boundary topographies. For the $Ra$ range explored, a weak temperature inversion is observed in the bulk of asymmetric rough cells. Finally, we remark that the temperature fluctuation at the cell centre and the Reynolds number associated with the large-scale circulation show universal power laws in terms of the flux Rayleigh number as $\sigma _{T_{c}}\sim Ra_F^{0.68}$ and $Re_{LSC}\sim Ra_F^{0.36}$ , respectively.

Numerical Investigation on the Effect of Air Humidification and Oxygen Enrichment on Combustion and Emission Characteristics of Gas Boiler

Gas boilers exhibit thermal inefficiency and unsatisfying pollutant emissions. In this study, numerical simulations were conducted to examine the effect of humidified oxygen-enriched air on methane combustion in a furnace and the effects of different premixed ratios of air on the temperature field inside the furnace, intermediate product OH groups, component concentration distribution, and pollutants. Although humidification of ambient air effectively reduced the flame center temperature and mass concentration of the NOx generated during combustion in the furnace, the highest growth rate of CO concentration at the furnace outlet was 18.6%. Humidification of oxygen-enriched air increased the center temperature and outlet NO concentration of the furnace compared with those during no oxygen enrichment, but the outlet CO concentration showed a decreasing trend, with the highest decrease rate of 34.6%. This study determined an optimal CO–air premix ratio with a moisture concentration of 50 g/kg dry air and an oxygen concentration of 23%. The air humidification and oxygen enrichment technology proposed in this article provides a technical reference for low nitrogen transformation of existing gas boilers.

A methodology to replicate LTGC engine conditions in a single-zone model and validate gasoline surrogate formulations versus experimental measurements

In this work, surrogate fuels for three premium-grade gasoline fuels were formulated and its autoignition behavior was validated, together with that of an existing surrogate for E10 regular gasoline, by comparison to experimental data measured in the Sandia Low-Temperature Gasoline Combustion research engine facility. Surrogate fuels have been previously designed by matching fuel properties such as octane number, fuel/air stoichiometric ratio and hydrogen/carbon ratio. However, similar octane rating can be obtained with several blends that will show different ignition characteristics. To avoid this issue, the surrogate fuels shown in this paper have been formulated by matching the main components of the fuel detailed hydrocarbon analysis. Validation of the surrogates was performed by replicating engine experiments run with the real fuel in a 0-D internal combustion engine reactor model with detailed chemistry. A fitted heat-loss model had to be implemented to properly replicate the experimental in-cylinder thermodynamic conditions, which invalidates the adiabatic assumption sometimes applied to engine simulations. Furthermore, minor species present in the EGR and residuals, such as CO and NOx, had to be taken into account to replicate the experimental low-temperature heat release (LTHR) trends. Therefore, accounting for heat losses and detailed in-cylinder composition are essential to accurately simulate the engine data. The bottom dead center temperature deviation required to obtain the same combustion timing as in the experiments was used as a metric to evaluate the accuracy of simulations. The surrogates gave good performance for the whole explored range, and replication of LTHR is a key factor in matching the experimental data. Chemical kinetic analyses showed that replication of LTHR is controlled by the ability of the surrogate to properly balance radical generation from low-temperature chain branching decomposition with radical consumption from stable species. Surrogate components that act as a sink of radicals tend to suppress the LTHR of the fuel, which may lead to large deviations between simulations and experiments. Especial attention should be paid to these fuel species when selecting the surrogate components.

Legionella in Primary School Hot Water Systems from Two Municipalities in the Danish Capital Region.

Legionella contamination in public water systems poses significant health risks, particularly in schools where vulnerable populations, including children, regularly use these facilities. This study investigates the presence of Legionella in the hot water systems from 49 primary schools across two municipalities in the Danish capital region. Water samples were collected from taps in each school, and both first-flush and stabile temperature samples were analysed for Legionella contents. The findings revealed that 97% of schools in Municipality 1 and 100% in Municipality 2 had Legionella in their hot water systems. The content of Legionella colonies was significantly higher in schools in Municipality 1, which was probably because of overall lower water temperatures. At stabile temperatures, 76% and 50% of the schools in the two municipalities exceeded the European Union's recommended limit of 1000 CFU/L. Stabile peripheral water temperatures were achieved after 3 min. Tap water temperatures above 54 °C and central tank temperatures above 59 °C were associated with Legionella contents below 1000 CFU/L. This study highlights the need for more stringent Legionella control procedures in schools, including higher water temperatures and refining Legionella reducing interventions with the addition of regular flow and draining procedures.

Enhancing heat dissipation for laser illumination by utilizing the phosphor in metal combined with vapor chamber (PiMCVC)

Laser-driven illumination has unique advantages in high-power applications. However, the low thermal conductivity of the phosphor converter and high-power density of the laser result in a serious heat dissipation problem. Although the thermal conductivity has been improved in the previous work, the heat transferred from the facula cannot be further dissipated. Herein, a phosphor in metal combined with vapor chamber (PiMCVC) was proposed. A copper foam skeleton structure (CFSS) coated with boron nitride (BN) was welded to an ultra-thin vapor chamber (UTVC). The heat dissipated from the facula can be transferred through the CFSS. The heat dissipation area is significantly enlarged by the UTVC. The facula central temperature of PiMCVC can be maintained below 107.0 °C under a load of 4.92 W while that of the reference sample is 530.18 °C. Even at a laser load of 11.58 W, the PiMCVC can still work normally with a luminous flux of 1568.37 lm. Due to the superior thermal management, under the laser power of 9.20 W, the PiMCVC sample can be stably operated for 720 min with a luminous flux of approximately 1150 lm and a CCT of about 4000 K. This work provides a new approach to the thermal management of high-power laser-driven illumination.

Preliminary study on temperature distribution and pyroelectric current of LiNbO3 heated by nanosecond pulse laser

In order to reduce the volume of compact neutron generators, a lot of investigations are carried out on generating high voltages by heating pyroelectric crystals with external heating. Laser irradiation is an effective non-contact heating method. Different laser parameters determine the crystal's temperature distribution, impacting the accelerating electric field. A preliminary study on the temperature distribution and pyroelectric current response of LiNbO3 heated by nanosecond pulse laser is presented, including both direct heating and heating with Cu and Ti disks adhered to the crystal. A two-dimensional transient heat transfer and circuit model is constructed in COMSOL. To validate the simulation model of temperature field distribution, FLIR thermal camera is utilized to measure the temperature in laser spot center experimentally. The experimental results coincide with simulations, which prove that the simulation model can predict temperature field distribution of the pyroelectric crystal effectively. This study can benefit the optimization of laser parameters for modulating high-quality deuterium ion acceleration fields.

The interior of Uranus

We present improved empirical density profiles of Uranus and interpret them in terms of their temperature and composition using a new random algorithm. The algorithm to determine the temperature and composition is agnostic with respect to the temperature gradient in non-isentropic regions and chooses amongst all possible gradients randomly that are stable against convection and correspond to an Equation of State (EoS) compatible composition. Our empirical models are based on an efficient implementation of the Theory of Figures (ToF) up to tenth order including a proper treatment of the atmosphere. The accuracy of tenth order ToF enables us to present accurate calculations of the gravitational moments of Uranus up to J14: J6 = (5.3078 ± 0.3312) 10−7, J8 = (−1.1114 ± 0.1391) 10−8, J10 = (2.8616 ± 0.5466) 10−10, J12 = (−8.4684 ± 2.0889) 10−12, and J14 = (2.7508 ± 0.7944) 10−13. We consider two interior models of Uranus that differ with respect to the maximal number of materials allowed per layer of Uranus (three versus four composition components). The case with three materials does not allow Hydrogen and Helium (H-He) in deeper parts of Uranus and results in a higher water (H2O) abundance which leads to lower central temperatures. On the other hand, the models with four materials allow H-He to be mixed into the deeper interior and lead to rock-dominated solutions. We find that these four composition components’ models are less reliable due to the underlying empirical models’ incompatibility with realistic Brunt frequencies. Most of our models are found to be either purely convective with the exception of boundary layers, or only convective in the outermost region above ~80% of the planets’ radius rU. Almost all of our models possess a region ranging between ~(0.75–0.9) rU that is convective and consists of ionic H2O which could explain the generation of Uranus’ magnetic field.

MgCr2O4/MgIn2S4 Spinel/Spinel S-Scheme Heterojunction: A Robust Catalyst for Photothermal-Assisted Photocatalytic CO2 Reduction.

Photocatalytic CO2 reduction technology has engaged significant attention due to its high efficiency, high selectivity, and environmental friendliness. However, its application is severely restrained by issues such as low separation efficiency of photogenerated carriers and a limited light absorption range. This work proposes an innovative MgCr2O4/MgIn2S4 magnesium-based spinel/spinel heterostructure photocatalyst to improve the photocatalytic CO2 reduction efficiency through the synergistic contributions of S-scheme heterojunction and photothermal effect. On the one hand, the unique S-scheme charge transfer mechanism enables the effective separation of photogenerated carriers. On the other hand, the photothermal effect allows an accelerated charge migration by increasing the reaction center temperature. Moreover, the abundant oxygen vacancies serve as electron traps and CO2 adsorption sites, unifying reaction and adsorption sites and substantially improving catalytic efficiency. Under UV-vis and UV-vis-NIR illumination, the average CO yields of the MgCr2O4/MgIn2S4 composite are 8.03 and 15.62 μmol g-1 h-1, respectively, greatly higher than those of pure MgCr2O4 and MgIn2S4 samples. Furthermore, the fabricated photocatalyst demonstrates excellent performance and structure stability. Therefore, this work may offer a new strategy for designing efficient and stable photocatalysts.

Numerical simulation of an externally heated fixed bed reactor for coal pyrolysis based on porous media

A cutting-edge three-dimensional transient model utilizing porous media has been developed to accurately simulate the pyrolysis process of externally heated coal. This innovative model comprehensively considers the evaporation and condensation of water, as well as the release of volatiles. In addition, it meticulously examines the change in coal seam porosity and the interphase heat transfer between pyrolysis gas and solid coal seam. The model's precision has been appropriately confirmed through validation against the central temperature evolution inside the experimental reactor. Notably, this model systematically illustrates various aspects, including the evolution of coal layer temperature, evaporation and moisture density, changes in coal layer density, porosity distribution, volatile release, and interphase heat transfer. The obtained results reveal that the heat absorption by moisture phase change causes the coal seam temperature to relatively stabilize at around the water boiling point for a period, thus delaying the initiation of the coal pyrolysis reaction. The pyrolysis gas released by center coal seam pyrolysis tends to flow radially toward the heating wall before flowing out of the reactor. Additionally, the change in coal seam porosity increases the heat transfer rate by an average of 1.5 °C/min during the rapid heating stage. The analysis also highlights the significant occurrence of interphase heat transfer throughout the pyrolysis process and elucidates its mechanism in various stages. Ultimately, this work offers essential theoretical guidance for the design, optimization, and scaling of subsequent externally heated fixed-bed coal pyrolysis reactors.

Multi-scale collaborative modeling and deep learning-based thermal prediction for air-cooled data centers: An innovative insight for thermal management

Investigating the data center (DC) thermal environment and temperature distribution is crucial to responding to unforeseen events such as equipment failure or environmental changes. However, building full-scale simulation models from DC room level to chip level faces significant challenges. In this paper, we propose a distinctive approach that combines multi-scale collaborative modeling with deep learning techniques for thermal prediction in air-cooled DCs. By taking the simulation results of the parent model as the boundary conditions of the child model, we constructed the DC multi-scale simulation model, which significantly reduces the model complexity and computational resources. Leveraging experimental data, the models at different scales were validated separately. The effects of different cooling strategies, air supply temperatures and air supply flow rates on multi-scale simulation models were investigated. Based on the parametric simulation approach, datasets for training data-driven models are constructed. Simultaneously, we propose the CNN-BiLSTM-Attention neural network model to predict the maximum CPU temperature and optimize the hyperparameters of the neural network through by Bayesian optimization. The prediction results of the coupled multi-scale model and the deep learning prediction model show that the absolute error is controlled within ±0.1 K, and the R2 value of the model evaluation metric is as high as 0.9899. Herein, the results provide valuable insights for enhancing thermal management in air-cooled DCs, paving the way for more efficient and resilient DC operations in the future.

Towards the perfect soft-boiled chicken eggs: defining cooking conditions, quality criteria, and safety assessments

In recent years, ready-to-eat soft-boiled chicken eggs, with coagulated whites and semi-solid yolks have become popular among Chinese consumers due to their convenience, tender texture, and nutritional benefits. However, the standards for these products are currently inconsistent, and quality evaluation parameters and food safety issues remain unclear. Softness ratio, representing the semi-liquid yolk proportion in a cross-section, was defined through a survey of different brands of ready-to-eat soft-boiled chicken eggs. By accounting for egg weight and cooking time, optimal softness under specific conditions was determined. A quality evaluation method was established based on the softness ratio and shelling score. Finally, the safety of soft-boiled chicken eggs was assessed by measuring yolk center temperature. The optimal softness ratio was 0.46 to 0.64. Optimal cooking times in boiling water (100°C) with a 5:1 water-to-egg ratio were 300 s for 43 to 48 g eggs, 330 seconds for 48 to 53g, 350 s for 53 to 58 g, and 370 s for 58 to 63g. After cooking, eggs were cooled for 6 min in an ice water mixture with a 3:1 water-to-egg ratio. Shelling scores (0-5) depended on the egg white surface exposed post-shelling, peaking at an air cell diameter of 21.55 ± 2.26 mm. Egg weight and shelling score had a correlation of -0.41, while egg white springiness and shelling score had a correlation of 0.86. Ensuring core yolk pasteurization standards was difficult, thus stricter management or whole egg irradiation was suggested for safety.

ThP7.14 - CSF Leak or Ear Wax? Logical Thinking in Emergency Management of a Collapsed Patient With Heat stroke

Abstract A man in his 60s presented to RESUS by ambulance on the hottest day of the year with suspected STEMI and collapse at home. The patient was intubated and unresponsive (GCS 5), with global rigors. Hospital ECG showed sinus tachycardia. Body temperature was in excess of 41°C, confirmed on central temperature monitoring. Bilateral clear fluid was noted to be discharging from both ear canals. Query CSF leak was indication for CT head, which was unremarkable. Considering this, efforts were focused on optimising body temperature. This was done with the use of ice packs and fans as well as continuous misting of cool water over the exposed patient. Improvement was shown with temperatures decreasing to 38°C. In questioning the cause of the “clear fluid,” a swab of it placed on an icepack swiftly returned the fluid to its natural consistency of ear wax. As a result of the extraordinarily high body temperatures, ear wax had melted in both ear canals and started to leak out, giving the impression of a CSF leak. This was simply identified at the bedside to refute the idea of a CSF leak. As CSF leak was the indication for a CT head, this could have been avoided with rapid cooling initiated earlier. Unfortunately, this patient later died due to heat stroke. Whilst avoiding the delay of a CT head most likely would not have changed the prognosis for this patient, it is useful to note the importance of logical thinking in an emergency setting.

Effect of viscous dissipation in heating/cooling of grade three fluid in a pipe subjected to uniform surface temperature

Forced convection in Newtonian and non-Newtonian fluids flowing through pipes maintained at uniform heat flux or uniform wall temperature are important for understanding heat transfer characteristics in design and thermal management of heat exchangers. Convective heat transfer in both Newtonian and non-Newtonian fluids flowing through pipes and parallel plates, subjected to uniform wall heat flux condition, were extensively studied by researchers. But for uniform wall temperature, studies on non-Newtonian fluids in pipes are rarely considered. Forced convective heating and cooling of a third-grade fluid, flowing in a pipe subjected to uniform (constant) wall temperature is considered. Effect of viscous dissipation is included in the energy equation. Separate energy conservation equations for heating and cooling are formulated and their dimensionless forms are obtained. Numerical solutions by shooting technique are obtained for the governing equations. The same equations are also solved by the least square method and semi-analytical solutions are yielded. Least square method is a widely used semi-analytical tool used for solving non-linear differential equations. Results of the numerical solution and semi-analytical solutions are compared and are observed to be in close agreement. This validates the numerical solution. Few important observations are presented. For heating, when the non-Newtonian parameter increases from 0 – 0.1, the peak temperature drops from 1.15 – 0.55 which occurs at the centre. In case of cooling, when non-Newtonian parameter increases from 0 – 0.1, the difference in central line temperature and wall temperature increases to 0.17 from 0.09. For change in the non-Newtonian parameter from 0.2 – 0.3, both for heating and cooling the peak temperature change is not drastic. Heat transfer coefficient, in case of heating, differs by nearly 3.5 when the non-Newtonian parameter increases from 0 – 0.1.

Effect of stepwise cooking on the water-retention capacity and protein denaturation degree of chicken breast

This study investigated the impact of different center temperatures (60 °C, 65 °C, 70 °C) combined with low temperature long time cooking (cooking at 60 °C for 30 min or 60 min) on the water-retention capacity of chicken breasts. The effects of different heat treatment methods on microstructure, texture parameters, water content, cooking loss, color, pH value, protein denaturation degree and secondary structure content of chicken breast were analyzed. The results revealed that both center temperature and low temperature long times cooking (LTLT cooking) time significantly influenced the water-retention capacity of chicken breasts (P < 0.05). With increasing heat exposure levels, there was a corresponding rise in pH value as well as protein solubility and hydrophobicity in meat. This led to increased alignment of myofibrils along with gradual structural disruption and connective tissue efflux resulting in significant increases in meat hardness, chewiness and cooking loss (P < 0.05). However, when the center temperature reached 70 °C with an LTLT cooking time of 60 min, the muscle fiber structure is almost completely destroyed, causing the connective tissue between the muscle bundles or fibers to refill, resulting in a random coil content increase of about 2%, increased the water content by around 12% and decreased hardness by about 31%. These findings demonstrate that the group subjected to a combination treatment involving a center temperature of 70 °C and an LTLT cooking time of 60 min was effective in enhancing the water content while reducing the hardness of meat.

Impact of Prewarming on Maintaining Perioperative Body Temperature: A Randomized Clinical Trial

PurposeTo determine the prewarming effect on body temperature in the perioperative period of patients undergoing conventional abdominal surgery and the level of thermal comfort. DesignA randomized controlled clinical trial. MethodsA Brazilian oncology hospital located in São Paulo. A total of 99 patients aged 18 years or over undergoing elective conventional abdominal surgeries, with a minimum duration of 1 hour of anesthesia. The study was carried out from 2019 to 2021. Patients were randomized into 3 groups: prewarming with a blanket and cotton sheet (control; n = 33); prewarming with a forced-air warming system for 20 minutes (intervention 1; n = 33); prewarming with a forced-air warming system for 30 minutes (intervention 2; n = 33). Central temperature was measured by a zero-heat-flux temperature sensor every 20 minutes from the preoperative period until the surgery end time. The level of thermal comfort was determined through self-report during the preanesthetic and postanesthetic periods. FindingsThere was a significant difference between the temperatures between the groups (P = .048), with evidence of greater benefit in maintaining the temperature in the group that received the prewarming intervention for 20 minutes. There was no significant difference between the percentage of temperatures below 36 °C among the groups (P = .135). Patients in the intervention groups were more comfortable during the postanesthetic recovery period than those in the control group (P = .048). Only 7 (8.24%) patients had postoperative chills (P = .399) and more than half of these incidents occurred in the control group (4; 13.3%). ConclusionsPrewarming for 20 minutes obtained the best results, showing the lowest average of temperature episodes below 36 °C during the intraoperative period and greater thermal comfort as reported by patients.