Peak Temperature Change Research Articles

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.

Thermoluminescence (TL) properties of Eu3+ incorporated with CaB4O7 phosphors prepared by solution-combustion process

The solution-combustion approach was used to create CaB4O7:Eu3+phosphors using Ba (NO3)2, Eu (NO3)3·5H2O, H3BO3, NH3(ON)H2, and NH4NO3 as source materials. We investigated the thermoluminescence (TL) characteristics of beta (β)-irradiated CaB4O7:Eu3+. When the TL intensity was evaluated at different dosages of β, it rose with the dose. Changes in peak temperature were observed because of the investigation of the effects of varying heating rates on TL glow curves. Moreover, the positions of the peak temperature and the TL intensity did not change when the same sample was measured again, suggesting that the sample was stable. Additionally, the study calculated several kinetic parameters, including activation energy (E), frequency factor (s), and geometrical factor (μg), for distinct TL glow curves. Through geometric analysis of TL glow peaks, the study determined activation energies and kinetic orders, enabling the calculation of the frequency factor. The findings highlight the suitability of the prepared phosphor for dosimetry and provide insights into trap characteristics crucial for continuous illumination at room temperature. The study also emphasises the importance of optimising trap depth for prolonged afterglow, shedding light on the interplay between trap energies and luminescence characteristics. These findings deepen our comprehension of phosphor behavior and open the door to better dosimetry applications.

Bimetallic FeCo-MOFs mediated Au nanorods etching for the multi-colorimetric and photothermal immunosensing of illegal additive

With the rapid expansion of the health food industry, the scope of safety supervision has also increased. However, traditional instrument detection methods cannot meet the requirements for the rapid on-site detection. Hence, the development of a rapid, precise, and simple method for the analysis of illegal additives in health foods is of great importance. In this work, by using FeCo-MOFs as mimetic peroxidase to mediate Au nanorods (Au NRs) etching, a dual-mode immunosensor based on multi-colorimetric and photothermal signals was fabricated to detect furosemide (FUR). In multi-colorimetric channel, the localized surface plasmon resonance (LSPR) peaks of Au NRs shifted blue, resulting in multi-color changes from red to gray to blue and finally to purple. In photothermal channel, the photothermal effect of Au NRs decreased, resulting in temperature changes. In the range of 1.0 × 10−5-1.0 × 10−2 μg/mL, both LSPR peak blue shift and temperature changes were linearly correlated with the logarithm of FUR concentration, with the detection limits were 4.9 × 10−6 and 8.5 × 10−6 μg/mL, respectively. Furthermore, its concentration can be accurately and intuitively assessed through the observation of vivid colorimetric changes. This advancement offers a highly promising approach for the on-site detection of FUR, facilitating timely and efficient monitoring, thereby significantly enhancing regulatory compliance and ensuring consumer safety.

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.

Experiment and Molecular Dynamic Simulation on Interactions between 3,4-Bis(3-nitrofurazan-4-yl) Furoxan (DNTF) and Some Low-Melting-Point Explosives.

3,4-bis(3-nitrofurazan-4-yl) furoxan (DNTF) is an explosive with excellent performance, and the use of DNTF as a high-energy component is of great significance for improving the comprehensive performance of weapons. To explore the effect of DNTF on low-melting-point molten carrier explosives, the compatibility between DNTF and other low-melting-point explosives was analyzed by differential scanning calorimetry, and mechanical sensitivity was tested. The compatibility and cohesive energy density between DNTF and other low-melting-point explosives were calculated by Materials Studio. The results showed that DNTF has good compatibility with most low-melting-point explosives, and the peak temperature change of the mixed system formed by melt-casting is not obvious. Among them, DNTF has the best compatibility with MTNP, TNT, and DNAN; moderate compatibility with DFTNAN and DNP; and the worst compatibility with DNMT. The sensitivity test results indicate that the combination of DNTF and TNT has the most significant reduction in mechanical sensitivity. DFTNAN and MTNP have better stability than DNTF and can generate strong interaction forces with DNTF. Other low-melting-point explosives mixed with DNTF have lower intermolecular forces than DNTF. The DNTF/MTNP system requires the most energy to phase change when heated compared to other mixed systems and is the least sensitive to heat. The DNTF/DNMT system has the lowest cohesive energy density and is the most sensitive to heat.

28Assessment of thermal variations in the pulpal chamber during fabrication of provisionals using two different techniques and three materials.

The issue of an increase in pulpal temperature affects direct and indirect techniques, where the fabricating material will come in direct contact with the prepared teeth. The aim of this study was to assess the pulpal thermal variations during provisional fabrication using direct and indirect-direct techniques, with three commonly commercially available provisional fabricating materials. In this vitro analytical study, 120 extracted human teeth were placed in a dentulous mould and dental stone was poured, to create a working model with an embedded natural right maxillary central incisor. Recording of thermal changes in the pulp chamber during provisionalization with direct (technique 1) and indirect-direct (technique 2) using three common types of provisional crown materials. 120 provisional crowns were fabricated using polymethyl methacrylate (DPI) (Group 1), Bis-acryl composite (Protemp 4) (Group 2) and Visible-light polymerizing (VLP) Urethane Dimethacrylate (Revotek LC) (Group 3) by two techniques and recording of peak temperature changes were done. Temperature rise in the pulp chamber was recorded using a thermocouple. The mean initial and final temperature of the pulp chamber recorded for Groups 1, 2 and 3 was 31.52, 32.56; 31.01, 32.34; 32.29, 34.47 for technique 1 and 29.13, 30.5; 29.29, 31.11; 30.31, 32.65 for technique 2. The mean change in temperature was higher in Group 3 compared to the other groups. The temperature rise detected according to this study was within the safer pulpal health limits with all the investigated materials and techniques. The resin material recommended for clinical use when the direct technique is employed for the fabrication of provisional crowns is bis-acryl composite resin (Protemp-4) as it caused minimal temperature rise in the pulpal chamber.

The 3D Printing and Evaluation of Surgical Guides with an Incorporated Irrigation Channel for Dental Implant Placement.

Dental implant insertion requires the preparation of the implant bed via surgical drilling. During this stage, irrigation is essential to avoid thermal damage to the surrounding bone. Surgical guides enhance the accuracy of the implant site preparation, but they mask the drilling site, hampering coolant delivery. A variety of designs are aimed at improving the coolant access to the target site. Using standard dental implant simulation software, this paper presents an in-house design and 3D printing workflow for building surgical guides that incorporate a coolant channel directed toward the entry point of the burr. The proposed design was evaluated in terms of the bone temperature elevations caused by drilling performed at 1500 rpm, under an axial load of 2 kg, and irrigation with 40 mL/min of saline solution at 25 °C. Temperature measurements were performed on porcine femoral pieces, in the middle of the cortical bone layer, at 1 mm from the edge of the osteotomy. The mean temperature rise was 3.2 °C for a cylindrical sleeve guide, 2.7 °C for a C-shaped open-sleeve guide, and 2.1 °C for the guide with an incorporated coolant channel. According to a one-way ANOVA, the differences between these means were marginally insignificant (p = 0.056). The individual values of the peak temperature change remained below the bone damage threshold (10 °C) in all cases. Remarkably, the distribution of the recorded temperatures was the narrowest for the guide with internal irrigation, suggesting that, besides the most effective cooling, it provides the most precise control of the intraosseous temperature. Further studies could test different design variants, experimental models (including live animals), and might involve computer simulations of the bone temperature field.

Physical modification of high amylose starch using electron beam irradiation and heat moisture treatment: The effect on multi-scale structure and in vitro digestibility.

This study explores a new strategy for manipulating the digestibility of high-amylose maize starch (HAMS) through combinative modifications, namely depolymerization via electron beam irradiation (EBI) followed by reorganizing glucan chains via heat moisture treatment (HMT). The results show that semi-crystalline structure, morphological features and thermal properties of HAMS remained similar. However, EBI increased branching degree of the starch at high irradiation dosage (20kGy), resulting in more readily leached amylose during heating. HMT increased the relative crystallinity (3.9-5.4% increase) and V-type fraction (0.6-1.9% increase), without significant changes (p>0.05) in gelatinization onset temperature, peak temperature and enthalpy. Under simulated gastrointestinal conditions, the combination of EBI and HMT either had no effect or negative effect on starch enzymatic resistance, depending on the irradiation dosage. These results suggest that the depolymerization by EBI predominantly affects the changes in enzyme resistance, rather than the growth and perfection of crystallites induced by HMT.

Effect of post-welding coating process on the organization and properties of MIG-welded T-joints of 6063-T6 aluminum alloy

Abstract With the rapid development of the precision industry, aluminum alloy structural parts have been widely used. However, in the welding process of aluminum alloy, there are problems such as welding deformation and weld tumor defects due to the special physical characteristics of aluminum alloy. Therefore, this paper mainly focuses on 6063-T6 aluminum alloy as the research object to analyze the effect of the coating process on the organizational properties of MIG welded T-joints of 6063-T6 aluminum alloy. First, based on the Simufact welding finite element analysis platform, the establishment of a three-dimensional welding simulation model, the simulation calculations and test results for comparison, the peak temperature and temperature change trend of each measurement point between the two. Secondly, according to the T-joint welding process, welding numerical simulation of 6063-T6 aluminum alloy rear compartment structural parts to obtain the rear compartment assembly welding residual stress is mainly concentrated in the vicinity of the weld. Finally, the impact of welding current on the organization and properties of T-shaped welded joints of 6063-T6 aluminum alloy was discussed. The results show that the coating process has a good strengthening effect on the mechanical properties of welded joints. Compared with the pre-coating process, the welded joint tensile strength increased by 14.93%, and the welding coefficient of 73% of the parent material heat-affected zone microhardness increased by 21.82% compared to the pre-coating process. In this paper, the finite element theory of the coating process and MIG welding, T-joint organization between the found welding heat-affected zone after the coating process can make Mg, and Si atoms continue to be enriched, and mechanical properties strength is enhanced.

Use of electrocautery devices for suture passage through the greater tuberosity: a biomechanical study.

The use of electrocautery to facilitate passage of a suture needle through bone without the aid of a drill or burr is a novel technique that has potential utility in orthopedic procedures, but there is a scarcity of research to support its utility. The specific aims of this cadaveric biomechanical study were to evaluate (1) the axial force reduction during suture passage using electrocautery when applied to rotator cuff repair, (2) the temperature change caused while using electrocautery, and (3) the failure loads and failure modes of this technique. Five matched pairs of fresh frozen humeri were used, classified into 2 groups: with electrocautery on needle (study group) and without electrocautery on needle (control group). Four individual osseous tunnels were made on the greater tuberosity around the insertion of the supraspinatus tendon. Each specimen was sequentially tested in 2 parts: a needle penetration test (part I) to measure the peak axial force and temperature change and a single load-to-failure test (part II) to measure the maximum load to failure as well as the mechanism of failure. A No. 2 FiberWire suture with a straight needle was used. In part I, the mean peak axial force was lower in the study group compared with the control group for all osseous tunnels but was not statistically significant for individual tunnels. However, there was a significant decrease in peak axial force in the study group of 36% compared with the control group overall (P=.033). There was no significant change in temperature of the tunnel site with the use of electrocautery (mean: 0.2±0.3°C, P=.435). In part II, 100% of the samples from each study group experienced bone tunnel failure. Forty percent of the trials in the study group found lower ultimate failure loads compared with the control group (reduction range: 7%-38%). There was no statistically significant difference in the ultimate failure load between either the loop tested or between the 2 study groups (loop 1: P=.352; loop 2: P=.270). Suture passage using electrocautery does significantly decrease the peak force needed to pass a needle directly through the greater tuberosity. This technique does not appear to burn the bone or weaken the bone tunnels. This technique may be useful during open rotator cuff repair or shoulder arthroplasty, although clinicians should be cautious when using this technique as its utility depends on bone quality and cortical thickness, and invivo results may differ.

Ratcheting of climate pledges needed to limit peak global warming.

The new and updated emission reduction pledges submitted by countries ahead of COP26 represent a meaningful strengthening of global ambition compared to the 2015 Paris pledges1,2. Yet, limiting global warming below 1.5°C this century will require countries to ratchet ambition for 2030 and beyond2-6. We explore a suite of emissions pathways in which countries ratchet and achieve ambition through a combination of increasing near-term ambition through 2030, accelerating post-2030 decarbonization, and advancing the dates for national net-zero pledges. We show that ratcheting near-term ambition through 2030 will be crucial to limiting peak temperature changes. Delaying ratcheting ambition to beyond 2030 could still deliver end-of-century temperature change of less than 1.5°C, but that would result in higher temperature overshoot over many decades with the potential for adverse consequences. Ratcheting near-term ambition would also deliver benefits from enhanced non-CO2 mitigation and facilitate faster transitions to net-zero emissions systems in major economies.

The path to 1.5 °C requires ratcheting of climate pledges.

Increasing climate ambition through 2030 will be crucial to limiting global peak temperature changes this century. Countries need to ratchet their 2030 pledges made in Glasgow to reduce temperature overshoot and consequently reduce the risks of irreversible and adverse consequences to natural and human systems.

Multi-scan laser bending of duplex stainless steel under different cooling conditions

This study focuses on the effect of three different cooling conditions during multi-scan laser bending of duplex stainless-steel sheet. Results show that the trend of temperature distribution with number of scans is almost similar in all three conditions, but the peak temperature changes. The bend angle, heat affected zone, tensile strength and hardness are significantly affected by the cooling condition. The tensile strength and hardness of scanned specimen is increased compare to base material in all three cooling conditions. The microstructure shows grain refinement and sigma phase formation at the top and bottom surfaces, respectively, in all three cooling conditions.

The structural, functional and digestive characteristics of acorn starch after combined debranching and heat–moisture treatment and their relationships

SummaryIn this work, acorn (Quercus suber) starch was first modified by debranching, and then subjected to heat–moisture treatment (HMT) at different temperatures (90 °C, 100 °C and 110 °C). Debranching and HMT could facilitate the aggregation of starch samples. The short‐range order and crystallinity were improved after debranching and HMT. The onset temperature (53.24 °C), peak temperature (63.41 °C), conclusion temperature (75.47 °C) and enthalpy change (11.38 J g−1) of native acorn starch increased after debranching and HMT. The solubility of native acorn starch increased after debranching, whereas the swelling power and freeze–thaw stability decreased. Compared with debranched starch, the freeze–thaw stability increased after HMT, while the swelling power and solubility decreased. Compared with native acorn starch, the water absorption capacity (WAC) was reduced after debranching, while the oil absorption capacity (OAC) was enhanced, and WAC and OAC of the debranched samples decreased after subsequent HMT. The total amount (72.98%, dry basis) of slowly digestible starch and resistant starch of native acorn starch after debranching and HMT increased significantly up to a maximum (80.36%, dry basis). These results indicated that the combination of debranching and HMT could be used as an effective strategy to improve the physicochemical properties of acorn starch.

Zinc oxide nanorods effect in micro structural and mechanical characteristics of aluminium composite material

In the present study, aluminium zinc oxide (Al-ZnO) nanorods composites with 3.5 and 5 wt% ZnO in Al were manufactured using powder metallurgy and microwave hybrid sintering. A fairly uniform reinforcement distribution and clear interface was perceived in the micro structural and energy dispersive spectroscopy analysis of composite material. It was observed from XRD analysis that no secondary (intermetallic) phase of Al and ZnO were present in the composite material. The simultaneous thermal analysis of the composites was done to understand the variation in the exothermic peak temperature and weight change percentage of composite material. The developed composite material with 5 wt% ZnO exhibited promising results in terms of micro-hardness (∼2 times), nano hardness (∼3.5 times) and elastic modulus (∼1.9 times) greater value compared to Al. The increased addition of ZnO nanorods in aluminium shows enrichment in properties rendering the material suitable for different engineering applications.

Effect of Fermented Lettuce Extract on Starch Retrogradation in Korean Rice Cake, Garaetteok

Starch retrogradation, i.e., reassociation or recrystallization of gelatinized starch, affects the flavor and texture of food. To prevent starch retrogradation, various methods such as replacement of chemically modified starch and use of hydrolytic and branching enzymes or additives have been studied. However, the relationship between fermented products and starch retrogradation has been not studied. Here, we investigated the effect of fermented lettuce extract on the retrogradation of Korean rice cake, garaetteok using Rapid Visco Analyzer (RVA), differential scanning calorimetry (DSC), texture analysis, and scanning electron microscopy (SEM). Fermented lettuce extract reduced peak viscosity, trough viscosity, breakdown, and setback of rice flour, as determined using the RVA. DSC revealed reduced onset temperature, peak temperature, and enthalpy change of cakes prepared from flour treated with fermented lettuce extract during storage compared with those of an untreated control. The change in the hardness of the treated rice cakes during storage, as determined via texture analysis, was smaller than that in the control. The surface of the fermented lettuce extract treated–rice cakes was found to be less cracked and porous than that of the control, as determined via SEM. Collectively, these findings showed that starch retrogradation during storage was retarded in fermented lettuce extract treated-rice cakes compared with untreated rice cakes. Therefore, these results suggested that fermented lettuce extract prevents starch retrogradation, improves food quality, and could be used as a food additive to retard starch retrogradation in the food industry.

Morphological, Thermal, and Mechanical Properties of Electrospun Recycled Poly(ethylene terephthalate)/Graphene Oxide Composite Nanofiber Membranes.

This study investigates the influence of graphene oxide (GO) on the properties of electrospun recycled poly(ethylene terephthalate) (rPET) composite nanofiber membranes. GO nanosheet layers, with good hydrophilic properties, were incorporated at various loadings (0–8 wt %) during electrospinning. The surface morphological analysis revealed that GO loadings of less than 0.5 wt % lead to smoother fiber surfaces due to less agglomeration, as shown by the scanning electron microscope images. The smooth fiber surface shows that the nanosheets are intact within the rPET polymer matrix at low GO loadings. The differential scanning calorimetry results reveal that nucleation increases linearly with GO content as observed by the change in crystallization peak temperature (Tc) of rPET from 184 to 200 °C. Both the Tc and characteristic rPET crystallization peak in the X-ray diffraction pattern indicate the presence of a physical interaction between the GO sheets and the rPET polymer matrix. A decrease of up to 10° in the water contact angle at 0.5 wt % GO loading; beyond this, it starts to increase due to the agglomeration of GO sheets. From this study, it is preferable to maintain the GO content to a maximum of 0.5 wt % to maximize hydrophilicity. This has the implication of enhanced filtration permeation flux in applications where hydrophilic membranes are desired.

Population Ethics and the Prospects for Fertility Policy as Climate Mitigation Policy

What are the prospects for using population policy as tool to reduce carbon emissions? In this paper, we review evidence from population science, in order to inform debates in population ethics that, so far, have largely taken place within the academic philosophy literature. In particular, we ask whether fertility policy is likely to have a large effect on carbon emissions, and therefore on temperature change. Our answer is no. Prospects for a policy of fertility-reduction-as-climate-mitigation are limited by population momentum, a demographic factor that limits possible variation in the size of the population, even if fertility rates change very quickly. In particular, a hypothetical policy that instantaneously changed fertility and mortality rates to replacement levels would nevertheless result in a population of over 9 billion people in 2060. We use a leading climate-economy model to project the consequence of such a hypothetical policy for climate change. As a standalone mitigation policy, such a hypothetical change in the size of the future population – much too large to be implementable by any foreseeable government programme – would reduce peak temperature change only to 6.4°C, relative to 7.1°C under the most likely population path. Therefore, fertility reduction is unlikely to be an adequate core approach to climate mitigation.

Impacts of long-term temperature change and variability on electricity investments

Long-term temperature change and variability are expected to have significant impacts on future electric capacity and investments. This study improves upon past studies by accounting for hourly and monthly dynamics of electricity use, long-term socioeconomic drivers, and interactions of the electric sector with rest of the economy for a comprehensive analysis of temperature change impacts on cooling and heating services and their corresponding impact on electric capacity and investments. Using the United States as an example, here we show that under a scenario consistent with a socioeconomic pathway 2 (SSP2) and representative concentration pathway 8.5 (RCP 8.5), mean temperature changes drive increases in annual electricity demands by 0.5-8% across states in 2100. But more importantly, peak temperature changes drive increases in capital investments by 3-22%. Moreover, temperature-induced capital investments are highly sensitive to both long-term socioeconomic assumptions and spatial heterogeneity of fuel prices and capital stock characteristics, which underscores the importance of a comprehensive approach to inform long-term electric sector planning.

Reversibility of the Hydrological Response in East Asia from CO2-Derived Climate Change Based on CMIP6 Simulation

Understanding the response of the Earth system to CO2 removal (CDR) is crucial because the possibility of irreversibility exists. Therefore, the Carbon Dioxide Removal Model Inter-comparison Project (CDRMIP) for the protocol experiment in the Coupled Model Inter-comparison Project Phase 6 (CMIP6) has been developed. Our analysis focuses on the regional response in the hydrological cycle, especially in East Asia (EA). The peak temperature changes in EA (5.9 K) and the Korean peninsula (KO) (6.1 K) are larger than the global mean surface air temperature (GSAT) response. The precipitation changes are approximately 9.4% (EA) and 23.2% (KO) at the phase change time (130–150 years); however, the largest increase is approximately 16.6% (EA) and 36.5% (KO) in the ramp-down period (150–160 years). In addition, the differences are below 5 mm/day and 1 day for the precipitation intensity indices (Rx1day and Rx5day) and frequency indices (R95 and R99), respectively. Furthermore, the monsoon rainband of the ramp-down period moves northward as the earlier onset with high confidence compared to the ramp-up period; however, it does not move north to the KO region. The results suggest that reducing CO2 moves the rainband southward. However, a detailed interpretation in terms of the mechanism needs to be carried out in further research.