Heating Duration Research Articles

Micro/Meso-Porous Double-Shell Hollow Carbon Spheres through Spatially Confined Pyrolysis for Supercapacitors and Zinc-Ion Capacitor.

Energy storage in supercapacitors and hybrid zinc ion capacitors (ZIC) using porous carbon materials offers a promising alternative method for clean energy solutions. The unique combination of hierarchical porous structure and nitrogen doping in these materials has demonstrated significant capacity for energy storage. Nevertheless, the full potential of these materials, particularly the relationship between pore structure configuration and performance, remains underexplored. Herein, a confined pyrolysis strategy based on the polymerization characteristics of polydopamine (PDA) was developed to construction of hollow carbon spheres with microporous/mesoporous dual shell structure. The depth of micropores and cavity can be controlled by adjusting the duration of heat treatment and hydrothermal treatment, in accordance with the decomposition and polymerization characteristics of PDA. Due to the elasticity of this structure, the relationship between the micro/mesoporous depth of the prepared carbon spheres and the energy storage performance in supercapacitors and ZIC is established. Through optimizing the ion transport capacity of carbon spheres and considering the influence of its internal cavity structure on energy storage, the resulting carbon spheres exhibit high specific capacitance of 389 F g-1 in supercapacitor and specific capacitance of 260 F g-1 and excellent stability with 99.3 % retention after 30000 chare/discharge cycles in ZIC.

Examining the impact of dry climates temperature on citrus fruit internal ripening

High temperatures alter the ripening process of citrus fruit, affecting quality, flavor, harvest time and marketing period. For example, citrus fruits ripen faster and are sweeter in tropical hot-humid climates than in Mediterranean warm-dry climates due to higher sugar accumulation and organic acid catabolism. Considering that: 1) over 60 % of the world's citrus exports come from countries with warm Mediterranean climates, and 2) the Mediterranean region is warming 20 % faster than the global average, the citrus industry will face significant challenges in the coming years. The range of high temperatures and the timing at which they determine sugar and acid content in dry climates have not been studied under field conditions. Therefore, a study was undertaken over 6 years to determine the relationship between high temperature and citrus ripening in two dry macroclimates, hot (Arid, in Morocco) and warm (Mediterranean, in Spain), and 5 microclimates of the Mediterranean region.Heat stress in these dry climates correlates with changes in fruit quality (lower juice and sugar content, and higher organic acids), depending on the maximum temperature threshold and the time of onset and duration of heat. In the arid climate, the heat stress threshold was found to be a significant number of days above 35 °C. This was particularly important at the beginning of summer (July in the northern hemisphere). However, in the current Mediterranean climate of Spain, the percentage of summer days above 35 °C is still low indicating that other microclimatic conditions are involved in determining fruit quality. In particular, an increase in the number of days with temperatures between 27 °C and 33 °C in late summer and early autumn was found to correlate with reduced citric acid concentration. Microclimate did not determine sucrose, fructose, and glucose concentrations.

Effect of precipitation hardening on the microstructure, mechanical, and corrosion properties of additively manufactured A20X aluminum alloy

The effect of age hardening treatment on microstructure, tensile properties, and corrosion behavior of additively manufactured A20X alloy was investigated. Three single-step aging temperatures (150 °C, 175 °C, and 200 °C) and one double-step aging temperature (pre-aging at 165 °C followed by aging at 185 °C) along with varying heat treatment durations ranging from 30 min to 144 h, were studied systematically. Microstructural characterizations revealed that the co-existence of coherent/semi-coherent (Ω, θ′) and incoherent precipitates (θ) resulted in the maximum hardening effect (up to 30 % higher microhardness). This improved the yield strength at room and 150 °C by 33.4 % and 22.6 %, respectively. Double aging delivered the best combination of microstructure with fine grains and optimal precipitate assembly in a short duration (12–16 h). The heat-treated LPBF A20X showed higher ductility and similar mechanical properties compared to the cast A20X. However, optimal precipitate characteristics reduced the corrosion potential by 13–16 % due to a higher galvanic reaction. The highest corrosion potential (−0.622 V) was achieved in the solutionized state.

Microstructural Evolution of Quaternary AlCoCrNi High-Entropy Alloys during Heat Treatment.

This study examines the microstructural evolution and mechanical properties of quaternary AlCoCrNi high-entropy alloys after heat treatment at 873 K for 72 and 192 h. The changes in nanostructure and phase transformation based on the heat treatment duration were as follows: B2 dendrite + BCC interdendrite and sigma phases after 72 h; B2 dendrite and interdendritic sigma phases + BCC after 192 h. After annealing, the morphology of the dendritic region shifted from spherical to needle-like, and the interdendritic region transformed from a spinodal-like to a plate-like morphology. Additionally, a phase transformation was observed in the dendritic regions of the annealed alloys at the nano-scale. The presence of the sigma phase in AlCoCrNi high-entropy alloys significantly improved the yield strength to around 1172 MPa; nevertheless, it decreased the compressive strain rapidly to 0.62%.

Effect of dry- and moist-heat treatment processes on the structure, solubility, and in vitro digestion of macadamia protein isolate.

This study aimed to enhance the solubility and digestibility of macadamia protein isolate (MPI) for potential utilization in the food industry. The impact of dry- and moist-heat treatments at various temperatures (80, 90, and 100°C) and durations (15 and 30min) on macadamia protein's microstructure, solubility, molecular weight, secondary and tertiary structure, thermal stability, and digestibility were investigated and evaluated. The heating degree was found to cause roughening of the MPI surface. The solubility of MPI after dry-heat treatment for 15 min at 100°C reached 290.96±2.80% relative to that of untreated protein. Following heat treatment, the bands of protein macromolecules disappeared, while MPI was stretched by vibrations of free and hydrogen-bonded hydroxyl groups. Additionally, an increase in thermal stability was observed. After heat treatment, hydrophobic groups inside the protein are exposed. Heat treatment significantly improved the in vitro digestibility of MPI, reaching twice that of untreated protein. The results also demonstrated that dry- and moist-heat treatments have distinct impacts on MPI, while heating temperature and duration affect the degree of modification. With a decreased ordered structure and increased random coil content, the dry-heat treatment significantly enhanced the in vitro digestibility of MPI. The digestibility of MPI after dry-heat treatment for 30 min at 90°C increased by 77.82±2.80% compared to untreated protein. Consequently, compared to moist-heat treatment, dry-heat treatment was more effective in modifying macadamia protein. Dry-heat treatment of 30 min at 90°C was determined as the optimal condition. PRACTICAL APPLICATION: Heat treatment enhances MPI characteristics, potentially advancing macadamia-derived food production, including plant-based beverages and protein supplements.

Distribution characteristics of radiant heat flux on tank surfaces exposed to wildland fires

AbstractThe expansion of wildland‐urban interface tends to expose fuel tanks to wildland fires, the frequency and intensity of which have increased in recent years due to climate change and global warming. This study aims to examine the distribution of radiant heat flux on a tank surface exposed to a wildland fire front, with a particular focus on extreme wildland fires. A theoretical framework is proposed, which consists of a flame length correlation, a thermal radiation model, and a correlation of time to failure, to calculate the radiant heat flux received by the tank surface and the potential for tank failure. The horizontal and circumferential distribution characteristics of the radiant heat flux are intensively discussed, in terms of the heat flux profile, heating area, total heat, time to failure versus the fireline intensity, fireline width, spacing, and tank volume. In particular, extreme wildland fires, characterized by large fireline intensities, could potentially destroy the tank within the safety spacing mandated by the current regulations. Therefore, a comparison between the time to failure and the radiant heating duration is suggested to ascertain the necessary safety spacing. The uncertainties in model calculations are also addressed, which arise from the use of different flame length correlations and flame radiative fractions.

Green synthesis and characterization of zinc oxide nanoparticles using Monoon longifolium leave extract for biological applications

The present study deals with the biosynthesis of zinc oxide nanoparticles (ZnO NPs) using the Monoonlongifolium (M. longifolium) leaf extract. The prepared ZnO NPs were characterized by XRD, FTIR, UV–Vis, TGA/DTA, and SEM. The synthesis parameters, such as plant extract volume (10–50 mL), heating duration (15 min), zinc nitrate concentration (1 mM), reaction time (1 h), and temperature (60 °C), were optimized. The synthesized ZnO NPs exhibited significant antibacterial activity against Staphylococcusaureus (22 ± 0.57 mm) and Escherichiacoli (19 ± 1 mm), as well as antifungal activity against Candidaalbicans (21 ± 0.16 mm), as determined by the agar-well-diffusion method. The minimum inhibitory concentration (MIC) of ZnO-NPs against S. aureus (6.25µg/mL) and E. coli (12.5 µg/mL), respectively, while the minimum fungicidal concentration (MFC) was 25 µg/mL against Candidaalbicans. Additionally, the antioxidant activity of the ZnO NPs ranged from 0 to 78% (IC50 = 12.5 μg/mL). These results demonstrate the potential of the synthesized ZnO NPs as effective antibacterial, antifungal, and antioxidant agents.

Highly sensitive analysis of fatty aldehydes in vegetable oils using a novel coumarin-based fluorescent probe by HPLC for quality control

A novel fluorescent probe, 3-(4-((hydroxylamino)methyl)-1H-pyrazol-1-yl)-7-methoxyl coumarin (HAPMC), has been designed and synthesized. The compound exhibits exceptional fluorescence properties due to a coumarin-pyrazolyl fluorophore. Moreover, it incorporates an N-hydroxylamine functional group capable of reacting with aldehydes to yield nitrone derivatives under mild conditions. This unique combination renders it an ideal derivatization reagent for aldehyde analysis. A standard method was established for the quantitative analysis of eight fatty aldehydes by utilizing high-performance liquid chromatography with fluorescence detection (HPLC-FLD) and a pre-column derivatization process, which has low detection limits (0.3–1.2 nM), satisfactory reproducibility (intraday and interday relative standard deviations in the range of 1.29 %-2.92 % and 1.73 %-3.45 %), and an extensive linear range (25–5000 nM) with excellent linearity (R2 ≥ 0.9989). The spiked recoveries of the fatty aldehydes range from 89.6 % to 106.0 %. The greenness and sustainability of our approach are reinforced by evaluations conducted with the AGREE and RGB 12 algorithms. The established method was successfully applied to the qualitative and quantitative detection of fatty aldehydes in nine real vegetable oil samples, including peanut, canola, rice, soybean, olive, rapeseed, corn, sunflower, and blended oils. The fatty aldehydes are known to have adverse effects on human health due to their carcinogenic and mutagenic properties. The findings revealed that hexanal and nonanal were the most prevalent saturated fatty aldehydes, with a notable increase in the total aldehyde concentration observed as the temperature and duration of heating increased. Compared to alternative analytical techniques, this pre-column derivatization method utilizing HAPMC displayed simplicity, reliability, and sensitivity. The results demonstrate the potential for broad application of this approach in various important research domains, including food quality control, environmental monitoring, and medical research.

Numerical and experimental study of thermography parameters for inspection of composites repaired by CFRP patches

ABSTRACT Considering the ever-increasing importance of composite patches applied to repair or reinforce composite structures, radical health monitoring of these patches seems inescapable. Thermography method is one of the most influential non-destructive methods applied to inspect the repaired structures. Since there are many parameters influencing defects detection in repaired composite structures, extracting the most influential method to determine these parameters is significantly important. In the present study, a repaired carbon fiber reinforced plastic (CFRP) composite structure having defects of different dimensions, types and features located in different depths, is investigated by experiment and finite element simulations to assess the influence of the experimental parameters, like the thermal excitation pulse duration and the best image frame. In thermal simulation, two criteria, maximum thermal variations versus time and path length, are developed to derive the most optimum heating duration and the best thermal frames. The obtained results are validated through defining direct and diagonal paths passing through defects demonstrated on thermography images and thermal map images. The average error of thermal variations on different paths displayed on thermography and simulation images is less than 4.5 percent which confirms the correspondence of obtained results of both mentioned methods.

A contemporary view of the mechanisms of formation of new contaminants in vegetable oils – esters of monochloropropanediols and high molecular weight carboxylic acids

Monochloropropanediols (MCPD) and their esters with high molecular weight carboxylic (fatty) acids are new types of technological contaminants present in refined deodorized oils and other foods.The development of measures to minimize the content of MCPD esters in vegetable oils, which are an important component of various food systems, is a priority direction of modern foreign and domestic research in the field of ensuring food safety. The effectiveness of such measures should be based on ideas about the mechanisms of formation of MCPD esters and the identification of their predecessors (precursors) present in the lipid complex of oil seeds, as well as those formed during their processing.Systematized statistically reliable scientific knowledge about the mechanisms of formation of MCPD esters and their derivatives is still missing. Presumably, the formation of MCPDs and their esters with fatty acids should correlate with the presence of chlorine compounds in oilseed raw materials and in the oil itself; chlorine-containing pesticides and biologically active substances (fertilizers) used in agricultural production are one of the sources.Thus, the goal of the research is a systematic and comprehensive synthesis of ideas about precursors and mechanisms of formation of MCPD esters.As a result of analysis and synthesis of literature sources, it has been established that the main precursors of MCPD esters are DAG, TAG and various chlorine-containing compounds. The main factors influencing the rate of formation and amount of accumulation of MCPD esters are high temperatures (more than 120°C), duration of heat treatment, the presence of free fatty acids, antioxidants and moisture. Different chlorine compounds appear to have different activities in the reactions leading to the formation of MCPD esters. The presence of antioxidants in lipid systems can inhibit the formation of 3-MCPD ester, and the effectiveness of the process is determined by the type of antioxidant. According to the degree of increase in inhibitory ability, the most applicable antioxidants in lipid systems can be ranked as follows: α-tocopherol, BOA, BOT, AP, PG and TBHQ. The role of the composition of fatty acids in the formation of MCPD esters still remains unclear; however, there is indirect evidence indicating the influence of the composition of fatty acids on the level of accumulation of MCPD esters, which determines the feasibility of an in-depth study of this issue.

Experimental behavior of axially loaded circular high-strength concrete-filled high-strength steel tubular stub columns after exposure to fire

The high-strength concrete-filled high-strength steel tubular (HCFHST) column is an innovative type of high-performance steel-concrete composite component, which has a broad prospect for engineering applications. To investigate the axial compressive behavior of post-fire HCFHST stub columns with circular cross-sections, twenty-five specimens were heated following ISO 834 standard fire and then loaded to failure under axial compression after being cooled. The effects of various heating durations, concrete and steel strength on the temperature distribution, spalling of the steel-concrete interface, post-fire ultimate bearing capacity and axial stiffness were analyzed. The residual ultimate capacity and axial stiffness of HCFHST stub columns experience a pronounced decrease as the heating duration increases. High strength steel has no significant contribution to the enhancement of the post-fire axial stiffness of HCFHST stub columns, and the effect level of high-strength concrete on the failure load of composite columns subjected to different heating durations is similar. Finally, the applicability of relevant equations for the residual compressive capacity of the ordinary strength CFST column to HCFHST stub columns was evaluated. The evaluation results revealed that available methods of conventional strength CFST stub columns cannot obtain accurate post-fire resistance predictions of circular HCFHST stub columns.

Effect of solid solution heat treatment duration on microstructure evolution and the high temperature and low stress creep properties of a low-cost fourth-generation single crystal superalloy

Low-cost Ni-based single crystal superalloy with high performance attracted much attention to the researchers in recent years. A Ru-free low-cost fourth-generation single crystal superalloy was designed in this study, which was rarely reported previously. This study mainly focused on the effect of solid solution heat treatment duration on the microstructure evolution and high temperature and low stress creep properties on the experimental superalloy. By the metallographic method, it was revealed that the dendritic segregation was gradually eliminated with the increasing solid solution heat treatment duration. Segregation of Al and Ta were well homogenized as well as W. Segregation of Re could still be observed after 32 h solid solution heat treatment. Quantity and fraction of pores increased, which has a significant influence on the creep properties. Compositional variation between dendritic and inter-dendritic region was the main factor that caused the qualitative difference in the size and volume fraction of the γ' phase. Gap of the γ' size and volume fraction between dendritic cores and inter-dendritic region after solid solution heat treatment became minor. Homogeneous dislocation networks formed during the creep test and the ruptured dislocation networks of the specimen subjected to 32 h solid solution heat treatment were found. In the tertiary stage of the creep test, the primary creep deformation mechanism is the super-dislocations with Burgers vector of a 〈010〉 shearing the rafted γ' phases. The specimen subjected to 16 h solid solution heat treatment has the optimal creep performance, followed by those subjected to 32 h and 8 h, respectively.

Effect of carburizing time treatment on microstructure and mechanical properties of low alloy gear steels

Gas carburizing significantly enhances the surface properties of low-alloy gear steels, resulting in superior micro-hardness, layer thickness, carbon content, and overall mechanical properties. Unlike other thermochemical processes such as nitriding and carbonitriding, which have limitations in core properties and hardening depth, gas carburizing offers unmatched surface hardness, wear resistance, and mechanical strength. This makes it ideal for demanding applications in the automotive, aerospace, and manufacturing industries. In this research, samples were gas-carburized for 4, 6, or 8 h. The results showed significant improvements: micro-hardness increased from approximately 140 HV to over 819 HV, and the surface layer thickness grew by more than 41%, from 1166 μm to 1576 μm. Additionally, the carbon content in the surface layer increased by over 450%, reaching up to 0.94 wt%. Clear correlations were observed between the duration of heating and the mechanical properties. Longer heating times, particularly after 8 h, raised ultimate tensile strength from 427.29 MPa to 778.33 MPa, while simultaneously decreasing elongation from 26.07% to 2.88% and resilience from 180 J cm−2 to 6.66 J cm−2. This optimization not only enhances surface hardness and durability but also improves key mechanical properties such as tensile strength, stiffness, resilience, and overall mechanical performance.

Microwave irradiation-induced deterioration of rock mechanical properties and implications for mechanized hard rock excavation

In this study, a novel microwave-water cooling-assisted mechanical rock breakage method was proposed to address the issues of severe tool wear at elevated temperatures, poor rock microwave absorption, and excessive microwave energy consumption. The investigation object was sandstone, which was irradiated at 4 kW microwave power for 60 s, 180 s, 300 s, and 420 s, followed by air and water cooling. Subsequently, uniaxial compression, Brazilian tension, and fracture tests were conducted. The evolution of damage in sandstone was measured using active and passive nondestructive acoustic detection methods. The roughness of the fracture surfaces of the specimens was quantified using the box-counting method. The damage mechanisms of microwave heating and water cooling on sandstone were discussed from both macroscopic and microscopic perspectives. The experimental results demonstrated that as the duration of the microwave irradiation increased, the P-wave velocity, uniaxial compressive strength (UCS), elastic modulus (E), tensile strength, and fracture toughness of sandstone exhibited various degrees of weakness and were further weakened by water cooling. Furthermore, an increase in the microwave irradiation duration enhanced the damaging effect of water cooling. The P-wave velocity of the sandstone was proportional to the mechanical parameters. Microwave heating and water cooling weakened the brittleness of the sandstone to a certain extent. The fractal dimension of the fracture surface was correlated with the duration of microwave heating, and the water-cooling treatment resulted in a rougher fracture surface. An analysis of the instantaneous cutting rate revealed that water cooling can substantially enhance the efficiency of microwave-assisted rock breakage.

Humidity modifies species-specific and age-dependent heat stress effects in an insect host-parasitoid interaction.

Climate change is projected to increase the frequency and intensity of extreme heat events, and may increase humidity levels, leading to coupled thermal and hydric stress. However, how humidity modulates the impacts of heat stress on species and their interactions is currently unknown. Using an insect host-parasitoid interaction: the Indian meal moth, Plodia interpunctella, and its endoparasitoid wasp, Venturia canescens, we investigated how humidity interacted with heat stress duration, applied at different host developmental stages, to affect life history traits. Hosts parasitized as 4th instar larvae and unparasitized hosts were maintained in high- (60.8% RH) or low-humidity (32.5% RH) at constant 28°C. They were then exposed to a 38°C thermal stress with a duration of 0 (no heat stress), 6 or 72 h in either the 4th or 5th host instar. Neither humidity nor heat stress duration affected emergence of unparasitized hosts, but increasing heat stress duration during the 4th instar decreased parasitoid emergence irrespective of humidity. When applied during the 5th instar, increasing heat duration decreased parasitoid emergence under low humidity, but no effect of heat stress was found under high humidity. Moreover, experiencing longer heat stress in the 4th instar increased host larval development time and decreased body size under high humidity, but this effect differed under low humidity; increasing heat duration in the 5th instar decreased parasitoid body sizes only under low humidity. Larval stage and heat stress duration directly affected parasitized host survival time, with a concomitant indirect reduction of parasitoid sizes. We show that humidity modifies key life history responses of hosts and parasitoids to heat stress in species-specific ways, highlighting the potential importance of humidity in regulating host-parasitoid interactions and their population dynamics. Finally, we emphasize that interactions between environmental stressors need to be considered in climate change research.

Determining patterns of leaching titanium(IV) from the Irshansky deposit ilmenite

The research object is the ilmenite concentrate from the Irshansky deposit. This study describes an elemental composition of the mineral raw material and confirms its structure using the X-ray diffraction and scanning electron microscopy. Experimental studies have shown that the ilmenite concentrate from the Irshansky deposit has a significant titanium content in terms of titanium dioxide (79 %). Mineral raw materials with such a chemical composition are unique, so there is a need to find alternative methods for its processing. The research demonstrates that the maximum degree of extraction in the process of alkaline leaching of the ilmenite concentrate is achieved under the condition that the average diameter of particles of the mineral raw material should be ≤71 μm. As a result of temperature studies, it has been found that a temperature of 453 K would suffice to obtain potassium titanate at atmospheric pressure. Further temperature increase does not provide for a significant increase in the degree of titanium extraction, and also contributes to the formation of polytitanates of various compositions. The study of the influence of the molar ratio of the starting reagents on the degree of extraction of titanium(IV) from the ilmenite concentrate has showed that the optimal molar ratio between the components corresponds to the stoichiometric one and is 1:2. Increasing the amount of potassium hydroxide in the reaction mixture is impractical as it reduces the yield of potassium titanate, and the final product will have high alkalinity due to excess alkali. The optimal time for alkaline leaching is three hours of continuous heating in a glycerin bath. A further increase in the duration of heating does not lead to an increase in the degree of extraction, which is associated with the diffusion of alkali from the surface of the nucleus into the volume of ilmenite particles due to the formed products of interaction and annihilation of the initial nuclei

The impact of heat stress on the human plasma lipidome.

The year of 2023 displayed the highest average global temperatures since it has been recorded-the duration and severity of extreme heat are projected to increase. Rising global temperatures represent a major public health threat, especially to occupations exposed to hot environments, such as construction and agricultural workers, and first responders. Despite efforts of the scientific community, there is still a need to characterize the pathophysiological processes leading to heat related illness and develop biomarkers that can predict its onset. Here, we performed a plasma lipidomic analysis on male and female subjects who underwent heat tolerance testing (HTT), consisting of a 2-h treadmill walk at 5 km/h with 2% inclination at a controlled temperature of 40°C. We identified 995 lipids from 27 classes, with nearly half of all detected lipids being responsive to HTT. Lipid classes related to substrate utilization were predominantly affected by HTT, with a downregulation of triacylglycerols and upregulation of free fatty acids and acyl-carnitines (CARs). We additionally examined correlations between changes in plasma lipids by using the physiological strain index (PSI). Here, even chain CAR 4:0, 14:0 and 16:1, suggested by-products of incomplete beta oxidation, and diacylglycerols displayed the highest correlation to PSI. PSI did not correlate with plasma lactate levels, suggesting that correlations between even chain CARs and PSI is related to metabolic efficiency versus physical exertion. Overall, our results show that HTT has a strong impact on the plasma lipidome and that metabolic inefficiencies may underlie heat intolerance.

Flame-catalytic infrared dry system for tomato continuous peeling

To eliminate the need for alkali and excess water while accelerating the industrial application of dry tomato peeling, a highly efficient industrial flame-catalytic infrared continuous peeling apparatus was designed. The synthesis of the catalytic layer (Pt/Al2O3) within the device was optimized to improve cost-effectiveness and enable modular installation, making it suitable for industrial applications. This study determined the optimal production parameters for industrial flame-catalytic infrared peeling (F-CIP) through experiments. Current findings demonstrated that, under optimal F-CIP conditions, characterized by a flame heating time of 5.8 s, an infrared heating temperature of 456 °C, an infrared heating distance of 70.6 mm, and an infrared heating duration of 246 s, peeling efficiency reached 99.2±0.9 %, with a peel loss of 4.1±0.3 %. Comparative analysis with lye peeling (LP) and hot water peeling (HWP) showed that F-CIP reduced hardness and peel loss and better preserved nutritional and antioxidant compounds. The mechanism responsible for the loosening and cracking of the fruit skin in the F-CIP peeling process involved a reduction in adhesion between the skin and the pulp due to the alteration of the pectin structure, an expansion of cell structure due to internal vaporization, and an increase in the Young’s modulus of the tomato skin. The F-CIP method, with its proven peeling efficiency, energy-saving attributes, and environmentally friendly features, is expected to attract increased attention from equipment manufacturers and the tomato industry. This paper serves as a foundational guide and contributes to the application and parameter control of F-CIP in the tomato peeling.

Research on the residual compressive properties of concrete with preload after sustained high temperatures

The containment vessel of nuclear power plants, concrete structures near the furnaces and roller lines, and chimneys, are exposed to high temperatures (120 °C to 350 °C) for long term. Research on the compressive properties of concrete after short-term high temperatures (usually within 3 h) has been widely conducted, while that of concrete after sustained high temperatures is scarce. In this research, the effects of temperature (120 °C to 350 °C), heating duration (3 h to 32 h) and initial stress level (0.2 to 0.6, ratio of initial applied stress to compressive strength at room temperature) on the failure mode, compressive strength, peak strain and stress-strain relationship of concrete after sustained high temperatures were studied. The results show that with increasing temperature and heating duration, concrete compressive strength gradually decreases, while concrete peak strain gradually increases. At heating duration of 24 h, the properties of concrete have basically stabilised. Preloading helps the concrete to resist the adverse effects of high temperatures by inhibiting the dehydration of cement matrix and the cracking of interfacial transition zone. For concrete with preload, transient thermal strain and short-term creep at high temperatures could not be recovered after cooling, which causes a significant increase in the peak strain of concrete. A compressive stress-strain model for concrete with preload after sustained high temperatures was developed, which consists of pre-creep ascending segment, creep segment, post-creep ascending segment and descending segment. Comparison of the prediction results with the test results proves that the model has high accuracy.

Microwave Welding of Thermoplastic using Silicon Carbide Nanowhiskers as Susceptor: Effect of Heating Duration

Microwave welding is becoming more popular than conventional joining methods due to its advantages such as rapid and localised heating as well as applicable to components with complicated geometry. Previously reported susceptor, such as carbonaceous materials and conductive polymers, are toxic and the welding process involving these susceptors is time-consuming. Because of its exceptional microwave absorption and biocompatibility, silicon carbide nanowhiskers (SiCNWs) was employed as the microwave susceptor for microwave welding. Microwave welding in this study comprises of only three simple steps: SiCNWs suspension preparation, SiCNWs application and microwave heating. The weld strength of welded joint was then characterised using tensile test and energy dispersive x-ray spectroscopy equipped scanning electron microscopy (EDS-SEM) to study its mechanical properties and cross-section microstructure. The influence of microwave irradiation time was studied in this study, and it is found that the weld strength rose with the extension of microwave irradiation time, until a maximum weld strength of 1.61 MPa was achieved by 17 s welded joint. The development of SiCNWs reinforced PP nanocomposite welded joint layer is responsible for the enhanced weld strength. Prolonged heating duration may also result in flaws such as void formation at the welded joint, which subsequently lowered the weld strength to 0.60 MPa when the heating duration was extended to 20 s. In sum, a strengthen welded joint can be formed with rapid microwave heating under the proper control of heating duration.