Peak Temperature Research Articles

Dy3+ doped Zn0.66Mg0.3Al2O4 nanophosphor for high dose radiation thermoluminescence dosimetric applications

Zinc Magnesium Aluminate doped with Dysprosium (Zn (1-x-y) Mg(y)Al2O4:x Dy (x=0.04 and y=0.3 mol%)) was prepared using the solution combustion synthesis method. The prepared phosphor was characterized using energy-dispersive X-ray spectroscopy, scanning electron microscopy, X-ray diffraction, transmission electron microscopy, and Fourier transform infrared, respectively, to study crystal structure, surface morphology, and vibrational properties. The thermoluminescence peak temperatures were 250°C, 248°C, and 246°C at irradiating doses of 600–1000 Gy, respectively. Through the computation of the activation energy (E), order of kinetics (b), and frequency factor (s−1), the kinetic parameters were assessed using the TL glow curve. It is observed from the TL dose-response curve that the intensity rises nearly linearly for all doses between 600 and 1000 Gy. Nanophosphor Zn0.66Mg0.3Al2O4:0.04Dy shows almost linear dose-response for a dose range of 600–1000 Gy and an optimum activation energy (E) of 0.93–0.97 eV, which makes it suitable for high-dose radiation thermoluminescence dosimetric applications.

Reactivity tuning of metastable intermolecular composite Al/PFOA by polydopamine interfacial control

Controlling the high reactivity resulting from interfacial contact between nanoscale components poses a significant challenge. This study introduces an approach utilizing an aluminum (Al) surface-modified material to regulate the interaction between Al and perfluorooctanoic acid (PFOA), employing an in-situ synthesized polydopamine (PDA) interfacial layer. The optimal ratio was determined through molecular dynamics simulations. Various characterization techniques, including scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS), were employed to comprehensively analyze the structure and elemental distribution of the samples. The findings indicate that the PDA coating process did not alter the surface structure of Al while maintaining the integrity of the functional groups of both PDA and PFOA. Results from simultaneous thermal analysis (TG-DSC) demonstrate that the PDA interfacial layer increased the pre-ignition reaction (PIR) peak temperature of PFOA/Al by 2 °C and enhanced the heat release of the PIR and fluorination reaction by 1.3 and 34.8 times, respectively. Thermal analysis kinetics investigation revealed a reduction of 6.66 kJ⋅mol−1 in the activation energy of the fluorination reaction and an increase of 20.28 kJ⋅mol−1 in the activation energy of the PIR. Furthermore, the combustion heat and reaction degree of PFOA/Al@PDA powder increased by 43.4 % and approximately 8 %, respectively, compared to PFOA/Al powder generated by physical mixing. This study demonstrated that the inclusion of PDA modifiers in the PFOA/Al system effectively controls the exothermic reaction between fuel and oxidant and enhances the oxidation degree of Al.

Effect of peak temperature on microstructure and mechanical performances of ART-Flash processed medium Mn steel

The combination of ART and Flash annealing has been utilized to enhance the mechanical properties of medium Mn AHSS, demonstrating significant effectiveness. However, the industrial application was constrained by the absence of research on the impact of critical processing variables. In this work, the peak temperature of the flash heating was varied in the intercritical field to manipulate the microstructure and mechanical response of a 5 wt% Mn steel. The mechanisms of microstructural evolution during heat treatment and deformation were thoroughly discussed through interrupted tensile testing. A collection of ultrafine multiphase structures, consisting of retained austenite (RA), ferrite, and martensite with flexible phase constituents, were constructed, resulting in an ultrahigh YS increment (∼450 MPa) and exceptional strength-ductility combination (YS: 1125 MPa, UTS: 1544 MPa, TE: ∼21 %). The significant strengthening is primarily attributed to the increase in α′-martensite, while the sustained TRIP effect induced by stable retained austenite is responsible for the appropriate ductility. The interaction between austenite and adjacent phases and grain size exhibit a crucial influence on the mechanical stability of austenite. Benefiting from the “shielding” effect provided by the surrounding martensite, the Flash-810 sample achieved great ductility, despite possessing only a 5 % volume fraction of retained austenite. The YS of the experimental steels is sensitive to peak temperature, while the UTS and ductility remains relatively stable. Our work suggests the substantial potential of intercritical flash heating in enhancing the mechanical response of medium Mn steels and the profound significance of controlling the peak temperature.

Experimental study under thermal shock environment to investigate effect of welding width on properties of ultrasonically welded joints of multiple copper cables

Based on the ultrasonic welding technology, this study uses three different welding widths to weld copper cables with different specifications. The influence of welding width on the mechanical properties and microstructure of each group of welded joints was systematically studied for the first time. The thermal shock test was carried out for each group of welded joints under optimum welding width to simulate the influence of severe temperature change environment on joint performance. It is found that the cross-sectional area of joint is 20 mm2 and optimal welding width of joint composed of two and three cables is 7 mm. The optimal welding temperature of the joint composed of four cables is 5 mm. Under the optimal welding width, the average shear strength of two-cable joint reaches 309.4 N. The four-cable joint is only 232.2 N. Moreover, the welding strength weakens significantly as the number of cables and the peak temperature decreases. The high temperature of bonding interface is the key factor to form a good weld. The peak temperature during welding is negatively correlated with the porosity of joint and positively correlated with peeling strength of joint. In addition, the morphology of ultrasonically welded joints has changed obviously after thermal shock test. With the participation of oxygen, the surface of welded joint is gray and bright brass, while the interior of joint is purple due to lack of oxygen. Moreover, the phenomenon of atomic diffusion and thermal expansion generates joints which were initially in a mechanically interlocked form and welding interface of the metallurgical bond under the action of high temperature. So the maximum joint peel strength is slightly improved.

Predictive Value of Physiological Values and Symptom Scores for Exacerbations in Bronchiectasis and Chronic Obstructive Pulmonary Disease With Frequent Exacerbations: Longitudinal Observational Cohort Study.

COPD (chronic obstructive pulmonary disease) and bronchiectasis are common, and exacerbations contribute to their morbidity and mortality. Predictive factors for the frequency of future exacerbations include previous exacerbation frequency and airway colonization. Earlier treatment of exacerbations is likely to reduce severity. This study tested the hypothesis that, in a population with bronchiectasis, COPD, or both who have frequent exacerbations and airway colonization, changes in symptom scores or physiological variables within 10 days prior to an exacerbation would allow the prediction of the event. We performed a 6-month, longitudinal, observational, cohort study among 30 participants with bronchiectasis, COPD, or both; at least 2 exacerbations per year; and colonization with Pseudomonas aeruginosa or Haemophilus influenzae. Daily symptom and physiological data were collected, comprising pulse rate, blood pressure, oxygen saturation, peak flow rate, step count, weight, and temperature. Exacerbations (defined as the onset of new antibiotic use for respiratory symptoms) were collected, and predictive values for abnormal values in the 10 days prior to an exacerbation were calculated. A total of 30 participants were recruited, collecting a total of 39,534 physiological and 25,334 symptom data points across 5358 participant-days; these included 78 exacerbations across 27 participants, with the remaining 3 participants not having exacerbations within the 6-month observation period. Peak flow rate, oxygen saturation, and weight were significantly different at the point of exacerbation (all P<.001), but no significant trends around exacerbation were noted and no clinically beneficial predictive value was found in the overall or individually adjusted model. Symptom scores tended to worsen for 10 days on either side of an exacerbation but were of insufficient magnitude for prediction, with area under the receiver operating characteristic curve values of ranging from 0.4 to 0.6. Within this small cohort with bronchiectasis, COPD, or both and airway colonization, physiological and symptom variables did not show sufficient predictive value for exacerbations to be of clinical utility. The self-management education provided as standard of care may be superior to either of these approaches, but benefit in another or larger cohort cannot be excluded. RR2-10.2196/resprot.6636.

Study on Oxygen Balance Regulation of TKX‐50 Based on Emulsion Method

AbstractDuring the process of external work, the energy of the negative oxygen balanced 5,5′‐Bi‐tetrazolium‐1,1′dioxyhydroxylammonium salt (TKX‐50) is not fully released, resulting in low energy utilization efficiency and the generation of harmful gases that pollute the environment. Based on this, in order to adjust the oxygen balance of TKX‐50, nano TKX‐50/AP composites with positive, zero and negative oxygen balance were prepared by emulsion method. The morphology of nano TKX‐50/AP composite was similar to that of hedgehog‐like spherical‐like particles, with many dense pores formed on the surface, and the average particle size was about 30 μm. During the composite process, part of TKX‐50 reacted with AP to form 5,5′‐bistetrazole‐1,1′dioxidamide (ABTOX). The first thermal decomposition peak temperature of zero‐oxygen balance TKX‐50/AP composite was 236.0°C, which was slightly reduced compared with that of TKX‐50. The second thermal decomposition peak temperature was 275.1°C, which was 22.2°C higher than that of TKX‐50. The heat release of zero‐oxygen balance TKX‐50/AP composite reached 2206 J g−1, which increased by 35.9% compared to TKX‐50, and the energy utilization efficiency was also greatly improved. The drop height of 50% explosion probability (H50) of zero‐oxygen balance TKX‐50/AP composite was 63.5 cm, and the explosion probability of friction sensitivity was 72%. Compared with TKX‐50, it increased by 15.1 cm and decreased by 28%, respectively. The results showed that the mechanical safety performance of TKX‐50 had been improved.

Comparison of non-premixed and premixed flamelets for ultra WET aero engine combustion conditions

The Water-Enhanced Turbofan (WET) is a future concept for aero engine applications being developed by MTU Aero Engines AG. Steam is injected into the combustion chamber to reduce temperature peaks and emission of pollutants. Depending on the steam content, the combustion process is modified. To analyze the effect of steam on the reaction kinetics and the temperature, detailed chemistry has to be employed. By comparing laminar flame speed and mole fraction distribution across the flame front, an appropriate chemical mechanism for the considered operating conditions including high steam loads was selected. Tabulated chemistry based on flamelets was employed, which enables the use of complex mechanisms in CFD analysis at reasonable computational costs. A comparison of premixed freely propagating flames and non-premixed counterflow diffusion flames to represent the manifolds was investigated. Various definitions of the progress variable are studied for ultra WET combustion considered under aero engine conditions. The manifolds from both model flames are compared from dry to ultra WET conditions with kerosene in an adapted Sandia Flame D large eddy simulation. While the premixed flamelets are generated efficiently, the results obtained with non-premixed flamelets are more reliable for the range of operating conditions investigated.

Electronic Passivation of Crystalline Silicon Surfaces Using Spatial‐Atomic‐Layer‐Deposited HfO2 Films and HfO2/SiNx Stacks

Spatial atomic layer deposition (SALD) is applied to the electronic passivation of moderately doped (≈1016 cm−3) p‐type crystalline silicon surfaces by thin layers of hafnium oxide (HfO2). For 10 nm thick HfO2 layers annealed at 400 °C, an effective surface recombination velocity Seff of 4 cm s−1 is achieved, which is below what has been reported before on moderately doped p‐type silicon. The one‐sun implied open‐circuit voltage amounts to iVoc = 727 mV. After firing at 700 °C peak temperature in a conveyor‐belt furnace, as applied in the production of solar cells, still a good level of surface passivation with an Seff of 21 cm s−1 is attained. Reducing the HfO2 thickness to 1 nm, the passivation virtually vanishes after firing (i.e., Seff &gt; 1000 cm s−1). However, by adding a capping layer of plasma‐enhanced‐chemical‐vapor‐deposited hydrogen‐rich silicon nitride (SiNx) onto the 1 nm HfO2, a substantially improved firing stability is attained, as demonstrated by Seff values as low as 30 cm s−1 after firing, which is attributed to the hydrogenation of interface states. The presented study demonstrates that SALD‐deposited HfO2 layers and HfO2/SiNx stacks have the potential to evolve into an attractive surface passivation scheme for future solar cells.

The development of undercut and bulge on a solidified surface

Abstract This study numerically investigates the development of undercuts and bulges parallel to the scanning direction on the surface solidified from a thermocapillary molten pool. The analysis considers various parameters, including power-off time, active solute concentration, beam power and radius, surface tension, liquid thermal conductivity, viscosity, and density. The formation and shapes of undercuts and bulges directly impact the yield, fatigue, fracture strength, and stress concentration in the solidified region. Unsteady two-dimensional fluid flow and heat transfer, which drive surface deformation in metals containing surface-active solutes (e.g., iron with sulfur), are solved using COMSOL Multiphase version 5.6. The development of the undercut, bulge, and molten pool is identified in six stages, based on whether the peak temperature is below the melting temperature, between the melting and critical temperatures, or above the critical temperature during heating and power-off periods. The critical temperature, determined as a function of solute content and temperature, leads to inward surface flow in the undercut near the pool edge, while the bulge in the central region can form due to either inward or outward surface flow. The predicted undercut depth and bulge height align well with previous scaling analyses and experimental data from laser polishing. These findings are relevant to various processes, including welding, additive manufacturing, polishing, melting, and solidification.

Effect of the synergistic interaction of zinc adipate, hydrotalcite and ethylene propylene rubber on the performances of polypropylene

Polypropylene (PP) is widely used in a range of areas due to its excellent physical and chemical properties, but its low-temperature brittleness and low-impact resistance largely limits its application. Hence, this study investigated the changes in mechanical and thermal properties of isotactic polypropylene (iPP) modified by the addition of the β-nucleating agent zinc adipate (ZnAA), the inorganic rigid particle hydrotalcite (HT), and the rubber elastomer bipropylene rubber (EPR). The structure and properties of modified PP were investigated by Fourier transform infrared (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), electronic universal material testing machine, and simple-beam impact testing machine. At last, the non-isothermal crystallization kinetics of iPP was investigated by the Caze method. It was found that with the addition of EPR reached 30 wt%, the notched impact strength of iPP was 34.74 kJ/m2, which was 542.43 % higher than that of pure iPP, and more than twice as high as that of ZnAA and HT modification, and the relative crystallinity ( K β) value of the β-crystalline form reached 79.66 % when 10 wt% EPR was added to the iPP. The addition of ZnAA, HT and EPR could significantly increase the crystallisation peak temperature ( T c), shorten the half-crystallisation time ( t 1/2) and increase the crystallisation activation energy ( ΔE) of iPP.

Comparative Study Between Design and Parameter Adjustment for Profit Maximization of Low-Density Polyethylene (LDPE) Production in High-Pressure Tubular Reactor

Low density polyethylene (LDPE) market becomes increasingly competitive and profit margins are tightening, manufacturers must create solutions to optimize profit in LDPE high pressure tubular reactors. Thus, in this study, the optimization of LDPE was proposed and conducted by improving the design and parameter adjustment of the LDPE tubular reactor. A mathematical model was developed and validated with industrial data by using MATLAB R2021. Input parameter study was carried out to investigate the effect of initiator concentration (CI), monomer concentration (CM), and solvent concentration (CS) to the ethylene conversion rate, reaction temperature rate, and final product grade, respectively. The CM was identified as the most significant parameter to influence LDPE polymerization process. CM increment results in the highest reaction temperature peak, which was originating from 249.58 to 299.21oC. The highest MFI value was also obtained when the CM was increased from 0.01954 to 0.01979 mol/cm3. Then, a comparative study between design and parameter adjustment for profit maximization in LDPE High Pressure Tubular Reactor was conducted. With the profit of RM166.83 million/year, compared to RM106.83 million/year, double reaction zones demonstrates that it has much better ethylene conversion rate compared to single reaction zone with optimization.

Investigation of Temperature at Al/Glass Fiber-Reinforced Polymer Interfaces When Drilling Composites of Different Stacking Arrangements

This attempt covers an investigation of cutting temperature at interfaces of Fiber Metal Laminates (FMLs) made of glass fiber-reinforced polymer (GFRP) stacked with an Al2020 alloy. GFRP/Al/GFRP and Al/GFRP/Al composite stacks are both investigated to highlight the effect of stacking arrangement on thermal behavior within the interfaces. In a first test series, temperature history is recorded within the metal/composite stack interfaces using preinstalled thermocouples. In a second test series, a wireless telemetry system connected to K-type thermocouples implanted adjacent to the cutting edge of the solid carbide drill is used to record temperature evolution at the tool tip. Focus is put on the effects of cutting speed and stacking arrangement on the thrust force, drilling temperature, and delamination. From findings, the temperature histories show high sensitivity to the cutting speed. When cutting Al/GFRP/Al, the peak temperature is found to be much higher than that recorded in GFRP/Al/GFRP and exceeds the glass transition point of the GFRP matrix under critical cutting speeds. However, thrust force obtained at constitutive phases exhibits close magnitude when the stacking arrangement varies, regardless of cutting speed. Damage analysis is also discussed through the delamination factor at different stages of FML thickness.

Improvement of thermal environment in the outdoor atrium by employing the spray system

Outdoor atriums have recently been applied with increasing frequency for natural illumination, but they produce a harsh thermal environment easily in summer. Moreover, overheating of the outdoor atrium necessitates air-conditioning to moderate indoor thermal comfort. Simultaneously, the substantial heat emissions from air-conditioning outdoor units worsen the outdoor thermal environment, creating a vicious cycle. Traditional passive evaporative methods involving water and greenery, while capable of regulating the thermal environment, suffer from low evaporative efficiency and pose significant challenges. To improve thermal environment in outdoor atriums, the spray system was employed due to its high cooling efficiency, especially in open or semi-open spaces. In this study, a comparative experiment was conducted to evaluate the effectiveness of using a spray system for evaporative cooling in open outdoor spaces. Furthermore, employing high-efficiency evaporative cooling through spraying to disrupt the vicious cycle of indoor and outdoor thermal environments. The dual goals include regulating indoor and outdoor thermal conditions while also mitigating the local heat island effect. Temperature and humidity distribution within the atrium and adjacent hallways were monitored, along with the impact on air-conditioning operation consumption in neighboring offices. Results showed that the spray system significantly improved the thermal environment in the outdoor atrium, reducing the average and peak air temperatures by 0.94–2.83 °C and 2.92–5.21 °C, respectively. It also resulted in a drop in the average temperature by 0.56–1.62 °C and the peak temperature by 2.31–3.25 °C in adjacent hallways. This effectively eased the issue of overheating in these areas while raising the comfort level in adjacent office spaces. The predicted mean vote decreased from 1.46 to 0.87, indicating a significant improvement in thermal environment in neighboring offices. Furthermore, the daily energy consumption was reduced by 10.6–12.4% in neighboring offices. This study provided the valuable guidance for improving thermal environments within outdoor atrium.

Enhancing horticultural harvest efficiency: The role of moisture content in ultrasonic cutting of tomato stems

Ultrasonic vibration has notable benefits in the harvesting and processing of tomato stems, particularly in reducing cutting force and minimizing moisture loss. Given the anisotropic nature of biological materials, the moisture content of tomato stems significantly impacts their physical properties. This study investigates the influence of varying moisture content on temperature and cutting force during the ultrasonic cutting of tomato stems. Initially, the moisture content of tomato stems at different maturity stages was measured using a water activity meter. Mechanical properties were characterized using a universal testing machine, and thermal properties were analyzed with a differential scanning calorimeter (DSC). Regression models were established to correlate moisture content with these material properties. Additionally, a three-dimensional microscopic model of stem skeletons, interfaces, and fiber bundles was created to simulate the fracture mechanisms during ultrasonic cutting under different moisture levels. Single-factor and response surface optimization experiments were conducted using a custom experimental setup under varying maturity stages, excitation frequencies, and voltage variations. Results showed that after 24 h, the peak temperatures for tomato stems at different maturity stages were 97.84 °C, 80.59 °C, and 74.15 °C, with corresponding cutting forces of 0.492 N, 0.544 N, and 0.998 N, respectively. The discrepancy between experimental results and simulation data was within 10 %. Higher moisture content was found to enhance the thermal conductivity of fiber materials, aiding in the fracture of fiber bundles, thus reducing cutting time and force. This study provides a theoretical foundation for the application of ultrasonic technology in the efficient harvesting and processing of industrial crops, with significant implications for horticultural crop treatment and processing.

Experimental study on laser-assisted machining of SiCp/Al composites considering laser preheating history based on in-situ observation

The application of laser-assisted machining (LAM) has been demonstrated to improve the surface integrity of SiCp/Al composites. The dynamic process of laser preheating affects the deformation mechanism of materials. In this paper, the laser preheating history under different parameters is characterized by the changes in peak temperature and instantaneous preheating temperature. SiCp/Al cutting experiments under different laser preheating histories are carried out based on the high-speed imaging system. The influence of laser preheating history on the shear angle and the spatial–temporal distribution of the physical information in the shear zone are analyzed by the digital image correlation (DIC) method. The deformation characteristics during the SiCp/Al composites cutting process under different laser preheating histories are discussed. Additionally, the influence of the laser preheating history on the surface integrity is analyzed according to the changes of the Al matrix and SiC particles under different combinations of peak temperature and instantaneous preheating temperature. It has been demonstrated that the deformation degree in the shear zone during LAM of SiCp/Al composites is depended on the material softening degree related to the peak temperature and the material deformation temperature dominated by the instantaneous preheating temperature. The deformation uniformity is primarily determined by the deformation temperature. An appropriate material softening degree and deformation temperature can improve the surface integrity. The results provide a foundation for further mechanism studies for cutting load and surface integrity in LAM of SiCp/Al composites.

Comparative study of flame propagation characteristics of methane explosion in pipeline with different venting structures at different ignition positions

The effect of central ignition and four types of explosion vents (circular vents with areas of 22.89, 15.20, and 9.07 cm2 and a cross-shaped vent with an area of 15.20 cm2) on the flame propagation of methane explosions was investigated by using a rectangular blast pipe system and analyzed in comparison with the closed-end ignition condition. Central ignition shows that the flame propagation velocity on both sides of the pipe increases and decreases. The peak pressure decreases as the vent area increases. Specifically, Pm (9.07 cm2) > Pm (15.20 cm2) > Pm (22.89 cm2). The flame temperature at the closed end was consistently higher than that at the vented end. The vm values in the closed-end ignition pipe increased by 20.0 %, 41.8 %, 45.8 %, 40.9 %, 31.5 %, and 19.0 %, respectively, over the central ignition position when the methane concentration was 8–13 %. When the methane concentration deviates from the stoichiometric ratio, the difference in peak pressure between closed-end and central ignition can be up to 0.15 MPa, which is 26.7 % of that of central ignition. The peak temperatures observed at points 1–2 in the closed-end ignition were consistently higher than the central ignition.

Insight into evolution characteristics of pyrolysis products of HLH and HL coal with Py-VUVPI-MS and DFT

To achieve a comprehensive understanding of the influence of chemical structure on the evolution characteristics of coal pyrolysis products, pyrolysis reaction of two kinds of low rank coal (Huolinhe and Huangling coal) were investigated with pyrolysis-vacuum ultraviolet photoionization mass spectrometry (Py-VUVPI-MS). The soft ionized mass spectral detection can provide evolved information of original pyrolysis product. The chemical structure of coal samples was characterized by solid-state 13C-NMR, indicating HLH coal with more branched chain and longer aliphatic chain structure. The bond dissociation enthalpies (BDE) of β-Cal-Cal and β-Cal-O within model compounds were obtained with density functional theory. The difference of peak temperature with maximum evolution was collected to investigate the effect of the chemical environment on evolution behavior of pyrolysis products. The results reveal that branched and long aliphatic side-chains can reduces BDE of β-Cal-Cal and β-Cal-O, resulting in the lower peak temperature of pyrolysis products derived from HLH coal. Substituent groups (such as alkyl and hydroxyl groups) attached on the aromatic rings can reduce peak temperatures. Moreover, the effects of the different substituted position on the aromatic ring of the methyl group presented on differences of the BDE. An increase in aromatic ring size correlates with a certain degree of reduction in BDE for β-Cal-Cal; consequently, peak temperature of pyrolysis products with larger aromatic rings is lower. The pyrolysis behavior of coal were discussed based on the experimental observations and theoretical calculation, which are beneficial to understand the reaction route and mechanism of coal pyrolysis.

Ultradian rhythms of activity in a wild subterranean rodent.

Many animals adapt their activity patterns to the best environmental conditions using daily rhythms. African mole-rats are among the mammals that have become models for studying how these rhythms can be entrained by light or temperature in experimental laboratory studies. However, it is unclear whether they exhibit similar circadian rhythms in their natural lightless, subterranean environment. In this study, we used biologging to investigate the activity rhythms of wild, highveld mole-rats. We show that their activity cycle exhibited an ultradian rhythm with a length between 4 and 8 h. On an individual level, mole-rats displayed about five activity bouts per day, occurring at various times during the day and night. On a population level, activity peaked in the afternoon, coinciding with the peak in ambient temperature. Our research suggests that wild subterranean mammals, which experience reduced environmental variation, are unlikely to show clear circadian rhythmicity in activity patterns. Instead, activity periods are distributed over several bouts throughout the day and night, and activity coincides with the peak in daily temperature. We propose that ultradian rhythms in activity may be more common than previously thought and discuss how physiological processes may generate differences in periodicity between laboratory and wild populations.

Implementation of a mixed-methods heat acclimation programme in a professional soccer referee before the 2022 FIFA world cup in Qatar: a case study

ObjectivesThis case study reports the real-world practicalities of implementing a mixed-methods heat acclimation (HA) programme before the 2022 FIFA World Cup.MethodsOne male English soccer referee (age: 44 years; height: 1.82...

Mutation of MeMinD increased amyloplast size with a changed starch granule morphologenesis and structures in cassava storage roots

Amyloplasts are the sites of starch synthesis and accumulation. Little is known about amyloplast division and its effects on the size, structure, and physicochemical properties of starch granules. In this study, we created mutants of plastid division-related gene MeMinD by CRISPR/Cas9 technology, leading to the disruption of normal division of amyloplasts in cassava storage roots. The memind mutants exhibited significantly enlarged amyloplasts with an increased number of starch granules, and broader range of granule sizes. The loss of MeMinD function led to transcriptional reprogramming of gene expressions related to starch-synthesizing enzymes, affecting the fine structure of starch. Starch in memind mutant storage roots showed a significantly decreased proportion of shorter amylopectin chains and an increased proportion of medium and long chains, which ultimately led to a significant increase in apparent amylose content (AAC) in memind mutants compared to that in WT. The changes in starch granule size and structure resulted in a significant increase in onset temperature (To), peak temperature (Tp), and conclusion temperature (Tc) of the gelatinization process, extending the time to reach peak temperature. These data suggest that regulating amyloplast division affects starch accumulation in cassava, presenting an effective strategy for developing novel cassava starch.