Increase In Peak Temperature Research Articles

Physicochemical properties of potato starch fermented by amylolytic Lactobacillus plantarum

This study investigated the effect of fermentation by Lactobacillus plantarum CGMCC 14177 strain on physicochemical properties and morphological characteristics of potato starch. The maximum total amylase and α-amylase production of L. plantarum CGMCC 14177 were 286.8 and 208.1 U/g, respectively. Fermented granules clearly exhibited pocked and dimpled surfaces. The granule properties changed to have a 1.9% increase in relative crystallinity. Overall the starch changed to have slight increases in onset and peak temperature, but resulted decreases of conclusion temperature and enthalpy. Fermentation decreased peak viscosity and breakdown value, while increased trough viscosity, final viscosity, and setback. Further analysis showed that fermentation increased the gel hardness and chewiness of the potato starch, but made little differences in the springiness, cohesiveness and resilience. Collectively, these results provide insight on how Lactobacillus strains can be used to modify the physicochemical properties of potato starch in ways that extend its use in industrial applications.

Effect of heat-moisture treatment on the structure and physicochemical properties of ball mill damaged starches from different botanical sources

The morphology, structure and physicochemical properties of ball milling (BM) damaged starches from mung bean, potato, corn and waxy corn were investigated before and after heat-moisture treatment (HMT) (100 °C, for 12 h at a moisture content of 25%). The results showed that the damaged starch (DS) content of BM modified starches was decreased by 4.49%, 10.68%, 17.11% and 22.98% after HMT for mung bean, potato, corn and waxy corn starch, respectively. The solubility and swelling power were significantly decreased, and the modified effect was depended on the type of starch, among which waxy corn starch exhibited the maximum reduction. Different degrees of aggregation and fusion of granules were found in starches modified with BM-HMT, and the extent of fusion was related to amylose content and crystalline pattern. The crystallinity of BM modified starches was increased by 6.3%, 5.9%, 17.9% and 22.4% after HMT for mung bean, potato, corn and waxy corn starch, respectively. The dual physical modification had various effects on the starches from different botanical sources, the increase in crystallinity and peak temperature (Tp) were related to the DS and amylose content, and the changes in gelatinization temperature range (Tc-To) were related to the crystalline pattern of starches.

Thermal decomposition mechanism of diisopropyl azodicarboxylate and its thermal hazard assessment

Thermal decomposition behavior and decomposition mechanism of diisopropyl azodicarboxylate (DIAD) were characterized and analyzed by C80 micro-calorimetery and STA-FTIR-MS system. And thermal hazard of DIAD was assessed by using self-accelerating decomposition temperature (SADT) as the evaluation index. The results show that only one exothermic peak appeared in decomposition process, and that the onset temperature and peak temperature increase with heating rate, whereas the released reaction heat at the heating rates remained approximately constant at 945.67±23.45 kJ/kg. Based on C80 data, the calculated activation energy of DIAD decomposition ranges from 45 kJ/mol to 77 kJ/mol by Friedman method, while the reaction progress in the range of 0.10–0.90. During thermal decomposition process of DIAD, there is only one stage of weight loss, which starts at about 80 ℃, reaches to the maximum rate of weight loss at 138 ℃, and end up at about 150 ℃. The thermal decomposition mechanism of DIAD can be mainly summarized as the route that the CO single bond breaks at first, then CC breaks, and the NN bond breaks subsequently, then the CO bond or the CN bond breaks, final products such as H2O, CO2 etc. appear from further dissociation and oxidation of molecular ionic fragments at last. According to the above-metioned results, the calculated SADT of DIAD is 89.0 ℃ based on Semenov model, when packed in 25kg standard package.

Effects of impregnation combined heat treatment on the pyrolysis behavior of poplar wood.

To investigate the effects of urea-formaldehyde (UF) resin impregnation combined heat treatment (IMPG-HT) on the pyrolysis behavior of poplar wood, the chemical composition, pyrolysis characteristics, pyrolysis kinetics, and gaseous products released during pyrolysis of untreated (control), IMPG-HT, IMPG and HT woods were analyzed. The results demonstrate that IMPG-HT changes pyrolysis behavior of poplar wood significantly. Unlike the control and HT samples, the thermogravimetric / derivative thermogravimetric (TG/DTG) curves of IMPG wood shift toward lower temperature, and the shoulder on DTG curves weaken or even disappear. The maximum mass loss rate of IMPG-HT samples decreases, and carbon residual yield increases to 23% or more and activation energy (E) increases sharply after conversion rate (α) reaching 0.80. HT improves the thermal stability of IMPG wood, which is represented by the increase of decomposition temperature (Td) and DTG peak temperature (Tpeak) and the higher E value of IMPG-HT wood. For the pyrolysis gaseous products, IMPG-HT wood produces nitrogen-containing gases (HNCO and NH3) due to the presence of UF resin, but the amounts of these gases are less than that produced by IMPG wood because the heat treatment had removed part of N elements.

Hydrothermal modifications of nonconventional kithul (Caryota urens) starch: physico-chemical, rheological properties and in vitro digestibility.

Effect of hydrothermal modifications (autoclaving, annealing and heat moisture treatment) on physico-chemical, rheological properties and in vitro digestibility of kithul starch was studied. Annealing and heat moisture treatment decreased swelling index, solubility and increased crystalline properties as compared with autoclaving. Autoclaving, annealing and heat moisture treatment caused significant morphological damages such as large holes and fissures on the kithul starch, in addition, granules changed from oval to donut shape. Heat moisture treatment formed higher number of agglomerated starch granules. Light transmittance decreased after hydrothermal modifications. Autoclaving and annealing increased the pasting viscosities (except break down viscosity) of kithul starch. A significant increase (p ≤ 0.05) in peak temperature, conclusion temperature and enthalpy was found in annealed and heat moisture treated kithul starches. The digestibility of kithul starch decreased with increasing resistant starch after annealing and heat moisture treatment. Autoclaved, annealed and heat moisture treated kithul starches exhibited higher value of storage modulus (G') and loss modulus (G″) than native kithul starch. It entail to higher firmness of modified starch gel. The current study showed that the remarkable changes formed by hydrothermal modifications increased the industrial acceptance of kithul starch.

Synthesis of Lithium Mangan Oxide (LiMn2O4) Using Solution Method for Lithium Ion Battery Catodes Materials

Synthesis of Lithium Manganese Oxide (LiMn2O4) for Lithium Ion Battery Cathodes with Solution Method has been conducted. This experiment was carried out using the solution method. In this study, the synthesis was carried out by varying the calcination temperature. The raw materials used were Lithium Acetate (C2H3O2Li), Manganese Acetate (C4H6MnO4.4H2O), Hydrochloric Acid (HCl), and Ethanol (C2H5OH) as solvents which were dissolved to become LiMn2O4 precursors. Synthesis was carried out at calcination temperatures of 600oC, 700oC and 800oC, for 4 hours then pounded with a mortar until smooth. The characterization includes: The results of the STA test at 280oC-380oC showed a mass decrease of 11.9973% due to the release of mass of water vapor and decomposition of C4H6MnO4.4H2O raw material. XRD analysis shows that the increase in peak temperature of the LiMn2O4 phase intensity is getting sharper, the peak showing the impurity Li2O phase decreases. SEM analysis results show that the higher the calcination temperature, the larger the particle size is formed, because in the calcination process the densification process occurs.

Shear-induced non-isothermal crystallization of poly(butylene adipate-co-terephthalate)

The influence of shear on non-isothermal crystallization of commercial poly(butylene adipate-co-terephthalate) (PBAT) was investigated. PBAT melt was sheared at 130 and 150 °C at rates of 10–100/s, and then cooled. The crystallization was followed by a light depolarization technique, whereas the crystallized specimens were analyzed by DSC, 2D-SAXS, 2D-WAXS, PLM and SALS. Shear flow shifted crystallization to higher temperature, and the effect was augmented by lower temperature of shearing as well as by higher shear rate and strain. Crystallization peak rate temperature of PBAT, sheared at 130 °C for 5 min at 100/s, increased by up to 12 °C. However, no evidence of crystal orientation due to shear was found, indicating that the shear induced the point-like nucleation. Only a small increase of melting peak temperatures, by up to 2–5 °C, was observed for the specimens sheared at the highest rates (≥50/s).

Karakteristik Termal dan Fungsionalitas Komposit Silika Sekam Padi dengan Aspal

This research was carried out to investigate the effect of asphalt addition to thermal characteristics, functional groups, physical properties (water absorption, water content, and swelling thickness) of rice husk silica. The mass ratio of silica and asphalt alloys were 1:0; 1:0,4; 1:0,5; and 1:0,6. Silica and asphalt were mixed at 160˚C followed by calcination at 150˚C for 3 hours. Thermal characteristics and phase structures were analyzed using Differential Thermal Analysis/Thermo Gravimetrical Analysis (DTA/TGA), X-ray Diffraction (XRD), and Fourier Transform Infrared (FTIR). DTA/TGA analysis results show that the addition of asphalt causes a decreasing in mass, on set temperature, maximum temperature, endothermic temperature And an increase in exothermic peak temperature. The results of XRD analysis showed that the addition of asphalt resulted in the appearance of amorphous carbon, shifting the range and the highest intensity of 2θ amorphous silica. The results of FTIR analysis showed that the addition of asphalt resulted in appearance the functional grups of C-H. The addition of asphalt causes a decrease in the value of water absorption, water content, and swelling thickness.

Characterization of Prata Banana (Musa AAB‐Prata) Starch: Native and Modified by Annealing

AbstractPrata variety banana starch is little known and has great economic potential due to its extensive cultivation in developing countries. This study characterizes this native starch and modifies by annealing at different temperatures (45, 50, and 55 °C). The native starch presents a high apparent amylose content (46.67%), besides it showing granules of several sizes and shapes containing rounded ends, which remain unchanged with the annealing. The weaker crystals are seen to be strengthened by the treatments at 50 and 55 °C, since the gelatinization onset and peak temperature increase. It also is possible to verify that the molecular order of the double amylopectin helices (ΔH) remains unaltered, but the uniformity of the molecular structure (Tc − To) increases. Regarding the pasting properties, annealing contributes to improving the paste's stability to heat and shear, but contributes to decreasing the stability of cooled starch paste. In addition, annealing increases the paste clarity and the least gelation concentration. Native starch stands out by its high resistant starch content (34.71%), which can be increased to 74.5% through annealing at 55 °C.

The sensitivity of the microstructure and properties to the peak temperature in an ultrafast heat treated low carbon-steel

In this work, we investigate the sensitivity of the microstructure and mechanical properties of an ultrafast heat treated low carbon-steel to the peak temperature. In all studied cases, the steel was heated within the intercritical temperature range (i.e. between the AC1 and AC3 temperatures). Both the peak temperature and soaking time were varied, and their effect on the size, the fraction of individual microstructural constituents and their tensile mechanical response were investigated. It is shown that the increasing peak temperature and soaking time promote austenite formation and recrystallization processes in the ferritic matrix. The highest nanohardness is shown by martensitic grains, while recovered ferrite demonstrated slightly higher nanohardness compared to recrystallized ferrite. The applied heat treatment parameters have a strong effect on the nanohardness of martensite, whereas the nanohardness of ferrite microconstituents is not sensitive to variations of peak temperature and soaking time. The non-recrystallized ferrite is harder than its recrystallized counterpart due to the higher dislocation density of the former. Increasing peak temperatures promote strengthening in the material at the expense of its ductility mainly due to increased martensite fraction. The steel demonstrates enhanced strain hardening ability independently of the peak temperature. Analysis of the experimental results showed that the industrial processing window of ±10 °C may lead to some heterogeneity of the local microstructure in the ultrafast heat treated sheets. However, the latter should not have any negative effect on the overall mechanical behavior of the ultrafast heat treated steel sheets on the macro-scale.

A generalised additive model to characterise dairy cows’ responses to heat stress

Heat stress is one of the most critical issues jeopardising animal welfare and productivity during the warm season in dairy cattle farms. The global trend of increase in average and peak temperatures is making the problem more and more serious. Many devices have been introduced in livestock farms to monitor and control temperature-humidity index, as well as animal behaviour and production parameters. The consequent availability of collected databases has increasingly enhanced the research aimed to understand the consequences of heat stress in cattle, in relation to genetic, reproductive, productive and behavioural features. Moreover, these investigations laid the foundations for the development, calibration, validation and test of numerical models quantifying the individual responses to heat stress conditions. In this work, a generalised additive model with mixed effects has been developed to analyse the relationship between milk production, animal behaviour and environmental parameters based on data surveyed in 2016 in an Italian dairy farm. Each cow has been characterised in terms of her response to heat conditions, and the results led to define three classes of susceptibility to heat stress within the herd. These attributes have then been related to the various phenotypic parameters collected by the precision livestock farming devices used in the farm. The study provides a model to understand the effects of heat stress conditions on individual animals in relation to the main parameters describing their rearing conditions; moreover, the results contribute to improve the herd management by lending indications to define targeted treatments according to the cow’s characteristics.

Thermal tolerance depends on season, age and body condition in imperilled redside dace Clinostomus elongatus.

Urbanization tends to increase water temperatures in streams and rivers and is hypothesized to be contributing to declines of many freshwater fishes. However, factors that influence individual variation in thermal tolerance, and how these may change seasonally, are not well understood. To address this knowledge gap, we studied redside dace Clinostomus elongatus, an imperilled stream fish native to rapidly urbanizing areas of eastern North America. In wild redside dace from rural Ohio, USA, acute upper thermal tolerance (i.e. critical thermal maximum, CTmax) ranged between ~34°C in summer (stream temperature ~22°C) and 27°C in winter (stream temperature ~2°C). Juveniles had higher CTmax than adults in spring and summer, but in winter, CTmax was higher in adults. Thermal safety margins (CTmax - ambient water temperature; ~11°C) were less than the increases in peak water temperature predicted for many redside dace streams due to the combined effects of climate change and urbanization. Furthermore, behavioural agitation occurred 5-6°C below CTmax. Safety margins were larger (>20°C) in autumn and winter. In addition, redside dace were more sensitive (2.5°C lower CTmax) than southern redbelly dace Chrosomus erythrogaster, a non-imperilled sympatric cyprinid. Body condition (Fulton's K) of adult redside dace was positively correlated with CTmax, but in juveniles, this relationship was significant only in one of two summers of experiments. Next, we measured CTmax of captive redside dace fed experimentally manipulated diets. In adults, but not juveniles, CTmax was higher in fish fed a high- vs. low-ration diet, indicating a causal link between nutrition and thermal tolerance. We conclude that redside dace will be challenged by predicted future summer temperatures, especially in urbanized habitats. Thus, habitat restoration that mitigates temperature increases is likely to benefit redside dace. We also suggest habitat restoration that improves food availability may increase thermal tolerance, and thus population resilience.

Mechanisms of thermal cycling damage in polycrystalline Sn-rich solder joints

Solder joints will experience elevated temperatures during operation due to resistive heating and ambient conditions. Device components have different thermal expansion characteristics, leading to straining of the solder joint and development of surface damage features. The anisotropic thermal expansion of βSn grains and discrepancy between the thermal expansion of intermetallic compounds causes degradation to be localized near grain boundaries and phase interfaces. Three experiments were conducted to investigate thermal effects on solder joint microstructure. Interrupted low temperature aging revealed the formation and movement of grain boundary ledges and uninterrupted thermal aging confirmed that the ledges formed during the cooling cycle of the experiment. Finally, high temperature thermal cycling demonstrated the acceleration of surface damage that accompanies an increase in peak temperature and cycling frequency. The orientation of the c-axis of the Sn matrix grains proved to be the critical feature controlling the direction of grain boundary ledge migration and type of surface deformation surrounding Cu6Sn5 intermetallic needles.

Composite Materials: Functional Soft Composites As Thermal Protecting Substrates for Wearable Electronics (Adv. Funct. Mater. 45/2019)

In article number 1905470, Yuhang Li, Jizhou Song, and co-workers report a functional soft composite, which incorporates an embedded phase change material with a thin metal film on the top in a soft polymer, as a thermal protection substrate for wearable electronics. Compared with conventional substrates, the proposed functional soft composite offers novel routes to manipulate heat flow and absorb excessive heat energy, which can reduce the peak temperature increase by 85%.

A Computational Modeling of the Influence of Different Oxy-fuel Combustion Environment on Combustion Characteristics and Particles Temporal History

ABSTRACT In the present article, CFD simulation of various oxy-fuel combustion cases has been performed to find out the influences of oxy-fuel combustion environment on temperature distribution, char consumption, radiative properties and temporal variation of particle phase variables such as particle temperature, volatile and char mass fraction. The oxy-fuel combustion cases are obtained by varying O2 and CO2 concentrations while keeping the total volume flow rate constant. Four oxy-fuel cases are considered in the present work having oxygen concentration 21%, 25%, 30%, and 35%. The present article also investigates the influence of char gasification reactions on temperature distribution, species concentration and temporal profile of particle char mass fraction. The predicted temperature distribution and radiative properties under oxy-fuel cases are compared with the corresponding values obtained under air-fired combustion as for retrofit existing power plants comparable values are desirable. The oxy-30 case having 30% oxygen has almost identical temperature and radiative profiles. With an increase in oxygen concentration in oxy-fuel cases leads to an increased peak temperature and surface incident radiation due to the rise in local stoichiometry, which results in enhanced reaction kinetics and burning rate. The peak temperature obtained in oxy-25, oxy-30 and oxy-35 cases is around 10%, 18%, and 24% higher than the oxy-21 case. Reduced char burnout time is obtained due to the presence of gasification reactions.

Compatibility of FeCrAlMo with flowing PbLi at 500°-650 °C

To explore the upper temperature limit of a fusion blanket utilizing eutectic Pb-17at.%Li for tritium breeding, a series of three mono-metallic thermal convection loops have been fabricated from alloy APMT (Fe–21Cr–5Al–3Mo) and operated with commercial PbLi and increasing peak temperatures of 550°, 600° and 650 °C, flow rates of 0.4–0.7 cm/s and temperature gradients of 85–115 °C. Chains of APMT specimens including 25 mm long tensile specimens were hung in the hot and cold legs of the loops to evaluate post-exposure room temperature tensile properties after 1000 h exposures in each experiment. For specimens exposed to flowing PbLi above 500 °C, only minor changes in tensile properties were observed after exposure. Most APMT specimens were pre-oxidized to form alumina prior to exposure and exhibited small mass losses as the alumina was partially transformed to α-LiAlO2 that tended to spall after exposure. Specimens without pre-oxidation exhibited higher mass losses and formed γ-LiAlO2 but with less spallation. While promising for increasing blanket temperatures, the small mass losses suggest that the surface oxide is not completely stable. However, even at the highest temperatures, there was no indication of classic dissolution/precipitation behavior suggesting that higher temperature compatibility may be possible.

Biochar from pyrolysis of biological sludge from wastewater treatment

It was studied the production of biochar by pyrolysis of biological sludge from wastewater treatment in the pulp and paper industry. The pyrolysis process was conducted in bench-scale fixed-bed reactor using distinct operating conditions of heating rate (2, 10, 20 and 30 ºC/min) and peak temperature (300, 375, 450, 525, and 600 ºC). The biochar yield is in the range 0.40 to 0.73 kg/kg dry sludge, and decreases with increasing peak temperature and heating rate. The organic matter content of the biochar is in the range 55.9 to 75.3%wt. (dry basis). Both the temperature increase and the heating rate increase promote the decrease of biochar volatile matter content within values between 14.4 and 48.4%wt. (dry basis). The biochar ash content increases with peak temperature and heating rate, and it has values in the range 24.7 to 44.1%wt. (dry basis). The corresponding fixed carbon content is between 26.2 and 42.4%wt. (dry basis), and increases with an increase in the peak temperature. The carbon concentration in the biochar is in the range 42.8 to 47.0%wt. (dry basis). The biochar pH is in the range 6.9 to 11.2, and the electrical conductivity (EC) is in the range 2.2 to 5.0 mS/cm.

Low intensity, continuous wave focused ultrasound reversibly depresses heart rate in anesthetized mice

Focused ultrasound (FUS) can noninvasively and reversibly modulate brain activity. Observed motor activity or behavioral changes are commonly used to infer neuromodulatory effects. Changes in autonomic nervous system regulation such as heart and respiratory function can potentially be used for studying the effects of FUS neuromodulation that do not produce outwardly observable motor or behavioral activity. In this study, low pressure (850 kPa), long duration (120 s) continuous-wave (CW) FUS at 2 MHz was targeted such that the focus spanned the visual cortex, hippocampus, and thalamus. These parameters were shown to reversibly depress heart rate in in vivo mice anesthetized with sodium pentobarbital by an average of 8.1 ± 3.7%. Following stimulus offset, heart rate either increased or varied in trend. Higher pressure (2 MPa), short duration (0.3 s) pulses at the same frequency resulted in either small, transient increases in heart rate or no change. Thermocouple measurements show the peak temperature elevation in the dura to be approximately 2 °C. Thermal simulations predict a peak temperature increase in the brain of 2.3 °C. These results indicate that CW FUS can alter autonomic nervous system regulation through very low heating and show that cardiorespiratory responses can be altered as a result of FUS neuromodulation.

Functional Soft Composites As Thermal Protecting Substrates for Wearable Electronics

AbstractThermal management of wearable electronics integrated with biological tissues remains one of the critical challenges for their practical applications. The undesired heating can cause thermal discomfort or even thermal damage to biological tissues. Here, a novel thermal protecting substrate design is proposed for wearable electronics with abilities to manipulate the heat flow and efficiently absorb the excessive heat energy without the compromise of substrate flexibility. The thermal protecting substrate features a functional soft composite, which incorporates the embedded phase change material with a thin metal film on the top in a soft polymer. Compared with conventional substrate, the proposed thermal protecting substrate can reduce the peak temperature increase by over 85% with appropriate parameters. Experimental and numerical studies reveal the fundamental aspects of the design and operation of functional soft composite to effectively avoid excessive heating of biological tissues. Influences of geometrical parameters on temperature reduction are investigated. Device demonstration of thermal protecting substrate in a wearable heater on pig skin illustrates the unusual capability to reduce the maximum skin temperature, thereby enabling practical applications of wearable electronics and creating engineering opportunities in biointegrated applications requiring thermal protection of biological tissues.

Thermal and mechanical properties of injection moulded heat-treated oil palm empty fruit bunch fibre-reinforced high-density polyethylene composites

ABSTRACTOil palm empty fruit bunch (OPEFB) was heat treated at 180°C using a vacuum oven for one hour, extruded and compounded with high-density polyethylene at 10%, 20% and 30% weight fraction. The composites then were injection moulded into dumb-bell shaped specimens. The effect of composition and heat treatment on the thermal properties of composites were investigated using Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). The tensile and flexural properties were also tested using an Instron Universal Testing Machine. TGA shows an increase in the degradation peak temperature of the heat-treated composites. DSC revealed an increasing trend in the degree of crystallinity (Xc) of the matrix as the heat-treated empty fruit bunch was used as a filler. An increment in the tensile modulus and tensile strain were observed for the treated fibre composites. In addition, the tensile strength value was increased for treated fibre composites with lower fibre loading.