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The Arrhenius equation was used to describe the dynamics of two-state switching in mesoscale, ferromagnetic particles. Using square permalloy dots as an idealized two-state switching system, measurements of the prefactor of the Arrhenius law changed by 26 decades over barrier heights from 30 to 700 meV. Measurements of the prefactor ratios for a two well system revealed significant deviations from the common interpretation of the Arrhenius law. The anomalous Arrhenius prefactors and the prefactor ratios can be fitted to a modified model that includes entropic contributions to two-state transitions. Similar considerations are likely for the application of the Arrhenius law to other mesoscale systems. [ABSTRACT FROM AUTHOR]

We present a quasi-elastic neutron scattering study of liquid deuterium hydride carried out using the Disk Chopper Spectrometer at the National Institute of Standards and Technology. Under saturated vapor pressure, the self-diffusion constant of deuterium hydride obeys an Arrhenius law D = D 0 exp − E A / k B T , where the prefactor D0 is given by D 0 = 9.5 ± 1.2 A ̊ 2 / p s and the activation energy is given by EA = 58 ± 2 K. We apply the quantum law of corresponding states to the known diffusion constants of the hydrogen isotopologues. From this application, we estimate that D 0 ≈ 9.1 A ̊ 2 / p s and EA ≈ 75 K in liquid tritium. Young's theory of quantum-mechanical effects in van der Waals fluids [Young, Phys. Rev. A 23, 1498 (1981)] is shown to apply to the diffusion constants of the liquid hydrogens. Our results underscore the importance of nuclear quantum effects in shaping the properties and behavior of the hydrogen isotopologues. [ABSTRACT FROM AUTHOR]

Thermal activation of a particle from a deep potential trap follows the Arrhenius law. Recently, this result has been generalized for interacting diffusive particles in the trap, revealing two universality classes—the Arrhenius class and the excluded volume class. The result was demonstrated with the aid of numerical analysis. Here, we present a perturbative hydrodynamic approach to analytically validate the existence and range of validity for the two universality classes. [ABSTRACT FROM AUTHOR]

In this work, we investigate the diffusion of LiCl electrolytes in 3D-nanoporous graphene structures (3D-NGSs) through molecular dynamics simulations. The diffusion coefficients, D, of water, Li+, and Cl− are calculated in 3D-NGSs with different LiCl concentrations, porosities, and surface charge densities under various temperatures. It is found that the diffusion coefficients follow the Arrhenius Equation and power laws for the dependence on the temperature and porosity, respectively. They decrease with increasing salt concentration. At high surface charge densities, the diffusion coefficients decrease with increasing charge density, which, however, plays a minor role in affecting the diffusion coefficients in the range of 0–0.2 C m−2. The mechanisms are investigated through the potential energy distribution in the 3D-NGSs. General scaling laws for the diffusion coefficients of water, Li+, and Cl− are proposed. The results in this work provide useful information for the design of electrodes and various energy systems. [ABSTRACT FROM AUTHOR]

ABSTRACT In this work, the etching characteristics of InGaZnO4 (IGZO) thin films were systemically investigated in inductively coupled CH4/Ar plasmas with various gas ratios, bias voltages, and surface temperatures. The ion flux in the CH4/Ar plasmas was analyzed using bias power and voltage, whereas the relative densities of CH and H radicals were quantified through optical actinometry. The change in CH3 radical density was also estimated based on plasma kinetics analysis. The correlations between the plasma properties and IGZO etch rate were investigated. In CH4/Ar plasmas with CH4 ratios below 80%, the IGZO etch rate increases with a higher CH4 proportion, aligning with the ascending trend of CH3 radical density, which suggests that CH3 radical density acts as a limiting factor (radical‐limited regime). However, the IGZO etch rate decreases when the CH4 ratio exceeds 80%, corresponding to the reduction in ion flux, which indicates that ion flux becomes a limiting factor in this ion‐limited regime. The IGZO etch rate shows a linear relationship with bias voltage and follows the Arrhenius equation with varying surface temperature in plasmas without bias voltage. A spontaneous etch model was proposed based on these relationships. In this model, the IGZO etch rate depends on CH3 radical density and IGZO surface reactivity, where ion bombardment contributes more significantly to surface reactivity than high surface temperature. IGZO thin film was deposited on SiO2 during the fabrication of a 3D stacked ferroelectric field‐effect transistor (FeFET) memory device. The interaction between IGZO and SiO2 during CH4/Ar plasma processing was investigated using time‐of‐flight secondary ion mass spectrometry. The efficacy of removing IGZO atoms that had diffused into the SiO2 network was enhanced when subjected to plasma with a bias voltage, compared to the process without a bias voltage. However, exposure to CH4/Ar plasma resulted in a deeper diffusion of IGZO atoms into the SiO2 network, primarily attributed to ion bombardment rather than elevated surface temperature. A significant improvement in surface smoothness was achieved after IGZO and SiO2 etch by introducing BCl3 into the SiO2 etching chemistry. [ABSTRACT FROM AUTHOR]

This paper presents the results of analytical studies of the combustion process of semi-coke, cedar sawdust, and their mixtures using the TGA method at three different heating rates with the determination of the main characteristics of heating: the presence of synergetic interaction between the components of the mixture affecting the maximum rate of combustion and kinetic parameters. Calculations of activation energy and pre-exponential multiplier of the Arrhenius equation by the Friedman and Ozawa–Flynn–Wall priori methods for initial combustibles and their mixtures have been carried out. Semi-coke was obtained by thermal treatment of brown coal at 700–900 °C to remove volatile substances, which makes it more environmentally friendly than the original coal. Semi-coke has a higher heat of combustion than biomass, and biomass has a higher reactivity than semi-coke. The combustion process of biomass occurs in a lower temperature range, and adding biomass to semi-coke shifts the combustion process to a lower temperature range than such for biomass. Adding at least 50% of biomass to semi-coke increases the combustion index by at least 1.1 times. Regardless of the heating rate of mixtures, synergetic interaction between the mixture's components increases the maximum combustion rate of coke residue by 20%. [ABSTRACT FROM AUTHOR]

A novel nickel-molybdenum carbide-graphite nanofiber composite is introduced as an electrocatalyst for ethanol electrooxidation. The proposed nanofibers have been prepared by calcinating electrospun nanofibers composed of nickel acetate tetrahydrate, molybdenum chloride, and polyvinyl alcohol. The calcination process was conducted at different temperatures (700, 850, and 1000°C) under a nitrogen gas atmosphere with a heating rate of 2.5 deg/min and a holding time of 5 h. Physicochemical characterizations have indicated that nickel acetate is entirely reduced to nickel metal during the sintering process, and molybdenum has bonded with carbon to produce molybdenum carbide. At the same time, the used polymer has been pyrolyzed to produce a carbon nanofiber matrix embedding formed inorganic nanoparticles. Electrochemical measurements concluded that molybdenum content and calcination temperature should be controlled to maximize the electrocatalytic activity of the proposed catalyst. Typically, the oxidation peak current density was 28.5, 28.8, 51.5, 128.3, 25.6, and 3 mA/cm2 for nanofibers prepared from an electrospun solution containing 0, 5, 10, 15, 25, and 35 wt% molybdenum carbide, respectively. Moreover, it was observed that increasing the calcination temperature distinctly improves the electrocatalytic activity. Kinetic studies have indicated that the reaction order is close to zero with a reaction temperature-dependent value. Moreover, it was detected that the electrooxidation reaction of ethanol over the proposed nanofiber composite follows the Arrhenius equation. The determined activation energy is 33 kJ/mol, which indicates good catalytic activity for the introduced nanofibers. Through the application of a set of visualization-based tools and the general linear model (GLM), the optimal conditions that generate the highest current density were identified. The computations unveiled that the optimal parameter settings are as follows: Mo content at 15 wt.%, methanol concentration of 1.55 M, and reaction temperature of 59°C. [ABSTRACT FROM AUTHOR]

The hot compression tests (T = 850–1100 °C, ε˙ = 0.1–10 s−1) of Cu–Cr–Ni bridge weathering steel with different Cr content (0.46% (#1), 0.64% (#2)) were performed on Gleeble‐3800‐D thermomechanical simulator. The effects of Cr content on hot deformation and microstructure evolution are systematically investigated by the Arrhenius constitutive equation, processing map, electron backscatter diffraction technology, and transmission electron microscope. In the results, it is demonstrated that the increase of Cr content from 0.46% to 0.64% enhances the solution strengthening and inhibits the dynamic recrystallization of the experimental steels during hot compression, resulting in the increase of flow stress. The Arrhenius constitutive equation with strain compensation is constructed. The increase of Cr content results in an augmentation of hot deformation activation energy, rising from Q#1 = 358.47 kJ mol−1 to Q#2 = 396.79 kJ mol−1, causing the increase of deformation resistance of Cu–Cr–Ni bridge weathering steel in hot compression. The optimal hot processing window of #1 and #2 experimental steels is as follows: ε˙ = 0.1–0.2 s−1, T = 1050–1100 °C, ε˙ = 0.1–0.15 s−1, and T = 1050–1100 °C, the increase of Cr content leads to the narrowing of the hot processing window of the experimental steels. [ABSTRACT FROM AUTHOR]

The presence of water in coal and its interaction plays pivotal roles in the storage and migration of coalbed methane (CBM), making it imperative to understand the water-occurrence across different coal ranks to guide CBM exploitation effectively. Here, a novel method for categorizing water into condensed and adsorbed forms based on their dehydration dynamics is proposed using differential thermogravimetric curve and the Arrhenius equation, offering a straightforward process and enabling the assessment of the interaction strength between water and coal. The result indicates that the total water capacity decreases initially before subsequently increasing as coal rank increases from 0.28 to 2.33% Ro,max, with the ratio of condensed water exhibiting an S-shaped curve. Remarkably, the condensed water capacity is correlated linearly with the total pore volume. The adsorbed water in low-rank coal is controlled primarily by the level of oxygen functional groups, whereas in medium-high rank coal it is controlled primarily by the specific surface area. Based on this, the controlling equations of water capacity and coal–water structure models were established. Additionally, coal–water interaction strength decreases significantly after the first coalification jump, with the strength of low-rank coal being approximately 2.54 times higher than that of medium-high rank coal. This discrepancy arises from the combined influence of multiple oxygen functional groups in low-rank coal on adsorbed water. This paper enhances the understanding of drainage process in coal reservoirs of varying ranks, which can facilitate the efficient extraction of CBM. [ABSTRACT FROM AUTHOR]

Fe-based materials exhibiting high dielectric constants have been attracting great attention due to their potential for application in electronic devices. In this work, iron niobate (FeNbO 4) fibres were produced by the Laser Floating Zone technique, applying three different growth speeds: 5, 10 and 25 mm/h. The XRD patterns showed the presence of two phases, being the FeNbO 4 the major one in all the samples. The effect of the growth speed is well perceptible in the morphology of the fibres. The dielectric measurements revealed that all samples have at least one dielectric relaxation phenomenon that is thermally activated, with the activation energy, estimated through the Arrhenius law, presenting values between 0.057 and 0.072 eV. The Nyquist plots showed the presence of a single semicircle for each temperature, that could be modelled by an equivalent electrical circuit consisting of an offset resistance in series with a parallel combination of a grain resistance and a grain constant phase element. The grain resistance increased with the increasing growth speed, from 574 to 64497 Ω, with the constant phase element showing the opposite trend, decreasing from 0.40 to 0.17 nF. [Display omitted] [ABSTRACT FROM AUTHOR]

Ethylene-propylene-diene monomer (EPDM) is a key engineering material; its mechanical characterization is important for the safe use of the material. In this paper, the coupled effects of thermal degradation temperature and time on the tensile mechanical behavior of EPDM rubber were investigated. The tensile stress-strain curves of the aged and unaged EPDM rubber show strong nonlinearity, demonstrating especially rapid stiffening as the strain increases under small deformation. The popular Mooney–Rivlin and Ogden (N = 3) models were chosen to fit the test data, and the results indicate that neither of the classical models can accurately describe the tensile mechanical behavior of this rubber. Six hyperelastic constitutive models, which are excellent for rubber with highly nonlinearity, were employed, and their abilities to reproduce the stress-strain curve of the unaged EPDM were assessed. Finally, the Davis–De–Thomas model was found to be an appropriate hyperelastic model for EPDM rubber. A Dakin-type kinetic relationship was employed to describe the relationships between the model parameters and aging temperature and time, and, combined with the Arrhenius law, a thermal aging constitutive model for EPDM rubber was established. The ability of the proposed model was checked by independent testing data. In the moderate strain range of 200%, the errors remained below 10%. The maximum errors of the prediction results at 85 °C for 4 days and 100 °C for 2 and 4 days were computed to be 17.06%, 17.51% and 19.77%, respectively. This work develops a theoretical approach to predicting the mechanical behavior of rubber material that has suffered thermal aging; this approach is helpful in determining the safe long-term use of the material. [ABSTRACT FROM AUTHOR]

The debate surrounding the roles of thermal and non-thermal pathways in plasmonic catalysis has captured the attention of researchers and sparked vibrant discussions within the scientific community. In this review, we embark on a thorough exploration of this intriguing discourse, starting from fundamental principles and culminating in a detailed understanding of the divergent viewpoints. We probe into the core of the debate by elucidating the behavior of excited charge carriers in illuminated plasmonic nanostructures, which serves as the foundation for the two opposing schools of thought. We present the key arguments and evidence put forth by proponents of both the non-thermal and thermal pathways, providing a perspective on their respective positions. Beyond the theoretical divide, we discussed the evolving methodologies used to unravel these mechanisms. We discuss the use of Arrhenius equations and their variations, shedding light on the ensuing debates about their applicability. Our review emphasizes the significance of localized surface plasmon resonance (LSPR), investigating its role in collective charge oscillations and the decay dynamics that influence catalytic processes. We also talked about the nuances of activation energy, exploring its relationship with the nonlinearity of temperature and light intensity dependence on reaction rates. Additionally, we address the intricacies of catalyst surface temperature measurements and their implications in understanding light-triggered reaction dynamics. The review further discusses wavelength-dependent reaction rates, kinetic isotope effects, and competitive electron transfer reactions, offering an all-inclusive view of the field. This review not only maps the current landscape of plasmonic photocatalysis but also facilitates future explorations and innovations to unlock the full potential of plasmon-mediated catalysis, where synergistic approaches could lead to different vistas in chemical transformations. The authors present a comprehensive review exploring the mechanistic understanding of plasmonic photocatalysis through examining the evidence for and interplay of thermal and non-thermal effects in this broad class of reactions. [ABSTRACT FROM AUTHOR]

The solid-state reaction method was employed to synthesize (1−x)[0.90NaNbO3–0.10Bi(Mg0.5Ta0.5)O3]–x(Bi0.5Na0.5)0.7(Sr0.7La0.2)0.3Ti0.9Zr0.1O3, denoted as (1−x)(NN–BMT)–xBNSLTZ (xBNSLTZ). XRD analysis of xBNSLTZ confirmed that all samples possessed a pure perovskite structure. SEM micrographs demonstrated homogeneous grain distribution and minimal porosity. With an increasing concentration of BNSLTZ, there was a gradual reduction in average grain size. Impedance spectroscopy was utilized to investigate the electrical properties of xBNSLTZ across a frequency sweep of 10 Hz–1 MHz and over a temperature range of 420–560 °C. The complex impedance and modulus spectra reveal non-Debye-type dielectric relaxation, indicative of two contributing mechanisms: grain and grain boundary effects on conduction. Electric modulus analysis indicated that the low-frequency relaxation process was temperature independent. The dc conductivity variation with temperature follows the Arrhenius equation. The ac conductivity was found to adhere to Jonscher power law. The Ea (the relaxation activation energy) and Ec (conductance activation energy) confirmed the relaxation mechanism of 0.3BNSLTZ is dipolar conduction. The dielectric properties showed a significant dependence on both frequency and temperature. A dielectric anomaly pointed to the presence of a single relaxation behavior. It was observed that an increase in BNSLTZ concentration led to a decrease in the maximum dielectric constant. Optimum performance was obtained with the 0.3BNSLTZ ceramics, which has the smallest average grain size (1.54 μm), considerable resistance value (R ~ 1000 K Ω c m ), and moderate dielectric constant (εr ~ 600), superior to the pure NN-BMT ceramic. These results demonstrate that the electrical property of the xBNSLTZ ceramics have some potential value in the application of electrical materials. [ABSTRACT FROM AUTHOR]

Azide-tetrazole tautomerism in a series of substituted 2-azidopyrimidines were studied by NMR spectroscopy methods. The structures of the tautomers existing in a solution were determined. By varying the temperature, the activation parameters of the studied tautomerism were determined from the integrated signal intensity in the NOESY/EXSY spectra. It was found that the phenyl substituents accelerate the tautomeric transformations. [ABSTRACT FROM AUTHOR]

Structure and mechanical properties for experimental heat-resistant steels with 12% Cr with a ferritic or ferritic- martensitic structure, as well as austenitic steel 08Kh18N10T after quenching from different temperatures (950 – 1250°C), are studied. The behavior of steels of different groups, classified according to structural features (grain size and phase content), under these conditions is analyzed. The effect of heating temperature for hardening on yield strength of steels at 20 and 720°C during static compression tests is demonstrated. [ABSTRACT FROM AUTHOR]

The mass transfer (diffusion) properties of a colloidal capillary-porous material (pears cut into plates 5 mm thick for convective drying) as a function of the moisture content of the material at different temperatures of the drying agent (air) were studied experimentally. Since the pear sample shrinks significantly during drying, the change in sample thickness during the process was taken into account when calculating the mass conductivity coefficient. At the same time, the linear shrinkage of the specified material was studied. The dependences of the mass conductivity coefficient on the moisture content of the material k = f(u) were obtained from drying curves based on the zonal method at a constant temperature of the drying agent tdr. They represent dependences concave to the abscissa axis that increase with moisture content, which is typical of dried materials. The minimum values of the mass conductivity coefficient on the graphs k = f(u) vary from 0.3∙10–10 m2/s at 30°C to 2.2∙10–10 m2/s at 60°C. With a change in the moisture content of the material, the mass conductivity coefficient changes multiply. The shrinkage data for engineering calculations was described by equation. The possibility of describing the temperature dependence of the mass conductivity coefficient (moisture diffusion) by Arrhenius equation is shown. The values of the Arrhenius equation parameters are obtained. [ABSTRACT FROM AUTHOR]

The study primarily focuses on the in situ synthesis of polystyrene (PS) and copper oxide (CuO) nanocomposites. An extensive analysis was conducted on the optical, thermal, mechanical, and electrical properties of PS with different CuO concentrations. The effective inclusion of CuO into PS was characterized by Fourier-transform infrared spectroscopy (FTIR), UV–visible spectroscopy, filed emission scanning electron microscopy (FE-SEM), X-ray diffractometry (XRD), differential scanning calorimetric analysis (DSC) and thermal gravimetric analysis (TGA). The reinforcement of CuO into the PS was established through FTIR. The optical bandgap energy deduced from UV–visible spectra decreases with CuO addition, whereas the refractive index rises significantly with the addition of CuO nanoparticles up to 7 mass%. The XRD analysis revealed the amorphous to crystalline transformation of PS with the homogeneous dispersion of nanoparticles. The SEM–EDX analysis revealed the uniform distribution of CuO nanofillers in the PS matrix. The CuO addition considerably increased the glass transition temperature and thermal stability of PS. The tensile strength, impact resistance and hardness of nanocomposite were significantly increased with the loading of CuO in the polymer matrix. The AC conductivity and dielectric constant of the PS was improved with the addition of CuO nanoparticles. The effect of temperature on conductivity, activation energy, and pre-exponential factor was determined using the universal power law and the Arrhenius equation. The highest electrical and mechanical properties were observed for 7 mass% nanocomposite. The synthesized PS/CuO nanocomposites with excellent optical characteristics, thermal stability, electrical conductivity, dielectric constant and mechanical strength can be used in supercapacitors and flexible nano-electronic devices. [ABSTRACT FROM AUTHOR]

Understanding the thermal aging kinetics of animal oils is of vital importance in the storage and applications of animal oils. In this work, we use four different techniques, including UV-Vis spectrometry, viscometry, impedance spectroscopy, and acid–base titration, to study the thermal aging kinetics of tallow, chicken oil, lard, and sheep oil in the temperature range from 120 °C to 180 °C. The evolutions of the UV-Vis absorbance, dynamic viscosity, electric impedance, and acid titration are discussed with the defect kinetics. The evolutions of the color centers, defects for dynamic viscosity, and electric dipoles follow second-order, first-order, and zero-order kinetics, respectively. The temperature dependence of rate constants for the evolutions of the UV-Vis absorbance, dynamic viscosity, electric impedance, and acid titration satisfies the Arrhenius equation with the same activation energy for individual animal oils. The activation energies are ~43.1, ~23.8, ~39.1, and ~37.5 kJ/mol for tallow, chicken oil, lard, and sheep oil, respectively. The thermal aging kinetics of the animal oils are attributed to the oxidation of triglycerides. [ABSTRACT FROM AUTHOR]

A bottleneck characterized by high strain and low hysteresis has constantly existed in the design process of piezoelectric actuators. In order to solve the problem that actuator materials cannot simultaneously exhibit large strain and low hysteresis under relatively high electric fields, Nb5+-doped 0.975(Ba0.85Ca0.15)[(Zr0.1Ti0.9)0.999Nb0.001]O3-0.025(Bi0.5Na0.5)ZrO3 (BCZTNb0.001-0.025BiNZ) ceramic thick films were prepared by a film scraping process combined with a solid-state twin crystal method, and the influence of sintering temperature was studied systematically. All BCZTNb0.001-0.025BiNZ ceramic thick films sintered at different sintering temperatures have a pure perovskite structure with multiphase coexistence, dense microstructure and typical dielectric relaxation behavior. The conduction mechanism of all samples at high temperatures is dominated by oxygen vacancies confirmed by linear fitting using the Arrhenius law. As the sintering temperature elevates, the grain size increases, inducing the improvement of dielectric, ferroelectric and field-induced strain performance. The 1325 °C sintered BCZTNb0.001-0.025BiNZ ceramic thick film has the lowest hysteresis (1.34%) and relatively large unipolar strain (0.104%) at 60 kV/cm, showing relatively large strain and nearly zero strain hysteresis compared with most previously reported lead-free piezoelectric ceramics and presenting favorable application prospects in the actuator field. [ABSTRACT FROM AUTHOR]

Understanding the response of aquatic microbial biofilms to changes in stream water temperature is crucial because temperature directly regulates microbial processes. We investigated the temperature sensitivity of benthic biofilm gross primary production (GPP) and respiration in a lowland stream during 3 seasons with contrasting thermal conditions (winter, spring, summer). We used laboratory-based incubations to estimate metabolic biofilm temperature dependence and applied the Arrhenius equation to estimate activation energy between seasons. As expected, the temperature sensitivity of GPP decreased with increasing in situ temperature conditions (i.e., higher activation energy values in winter and spring compared with summer), suggesting that biofilm GPP rates were more sensitive to temperature change during colder seasons. In contrast, temperature sensitivity of respiration was the lowest in spring, suggesting a limited response to ambient temperature increases and the predominant role of other environmental variables on biofilm temperature sensitivity. Our findings indicate that biofilm metabolic balance is inconsistent with seasonal temperature changes and underscore the importance of considering other environmental variables that influence aquatic microbial biofilm responses to warming. [ABSTRACT FROM AUTHOR]

The rise in early-age temperature concrete structures, driven by the exothermic reactions during cement hydration, significantly increases the risk of thermal cracking. To address this issue, the construction industry employs several strategies, including the partial substitution of cement with ground granulated blast furnace slag (GGBS) due to its lower heat of hydration. Accurately predicting the hydration temperature of concrete is critical for preventing thermal cracking. This task becomes more complex, with fluctuating ambient temperatures influencing hydration kinetics and heat dissipation. Previous studies often assume adiabatic or isothermal conditions, thus overlooking the impact of ambient temperature variations. This paper presents an innovative finite element modelling (FEM) approach to simulate the hydration temperature progression in in situ concrete slabs, incorporating the effects of ambient temperature fluctuations. Isothermal calorimetry curves were adjusted using the Arrhenius-based approach to express the cement hydration rate as a function of ambient temperature. The FEM outcomes, validated with semi-adiabatic calorimetry tests, demonstrate the model's capability to forecast temperature development in in situ concrete under varying ambient conditions. Additionally, the study examines the influence of partial cement replacement with GGBS on thermal behaviour, revealing that while GGBS effectively reduces thermal reactions at higher contents, its efficacy diminishes with rising ambient temperatures. [ABSTRACT FROM AUTHOR]

The calculation of the activation energy helps to understand and to identify the underlying phenomenon of oxidation. We propose a new method without any a priori hypothesis on the oxidation law, to retrieve the activation energy of partially and totally oxidized samples subject to successive annealing. The method handles the uncertainties on the measurement of metal and oxide thicknesses, at the beginning and at the end of the annealing process. The possible change in oxidation law during annealing is included in the model. By using an adapted Particle Swarm Optimization method to solve the inverse problem, we also calculate the time of final oxidation during the last annealing. We apply the method to successive annealings of three samples with initial nanometric layers of copper, at ambient pressure, in the open air. One, two and three successive laws are recovered from experimental data. We found activation energy values about 105–108 kJ mol − 1 at the beginning of the oxidation, 76–87 kJ mol − 1 at the second step, and finally 47–59 kJ mol − 1 in a third step. We also show that the time evolution of copper and oxide thicknesses can also be retrieved with their uncertainties. [ABSTRACT FROM AUTHOR]

CI, CM, and CR carbonaceous chondrites contain hydrous minerals, indicating that their parent bodies underwent aqueous alteration at low temperatures. Some of these chondrites, such as heated CM, CI, and CY chondrites, experienced thermal dehydration by impacts or solar radiation after aqueous alteration. This study conducted heating experiments on carbonaceous chondrites and evaluated their dehydration/dehydroxylation kinetics in an effort to explain the thermal history of the parent asteroids of heated carbonaceous chondrites using their degrees of dehydration/dehydroxylation of hydrous minerals. Murchison (CM2.5) and Ivuna (CI1), relatively primitive (having not undergone thermal alteration) carbonaceous chondrites, were used as starting materials. Weakening in the OH band at ~3680 cm−1 (2.72 μm) with isothermal heating at 350–500°C (Murchison) and 450–525°C (Ivuna) were observed under in situ infrared spectroscopy (FT‐IR) equipped with a heating stage. To determine the rate constants, the decrease in the OH band was fitted using kinetic models such as first‐order reactions, two‐dimensional diffusion, and three‐dimensional diffusion. The apparent activation energies and frequency factors were determined using the Arrhenius equation. Time–temperature transformation diagrams were drawn to represent the decrease in the OH‐band intensity as a function of temperature and heating duration. Such kinetic approaches can provide constraints on the temperature and time of the dehydration/dehydroxylation processes and enable us to estimate long‐term effects from experiments in the laboratory within a short time. [ABSTRACT FROM AUTHOR]

Copyright of Food & Fermentation Industries is the property of Food & Fermentation Industries and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Graphene/copper composites are promising in electronic and energy fields due to their superior conductivity, but microstructure control during thermal mechanical processing (TMP) remains a crucial issue for the manufacturing of high-performance graphene/copper composites. In this study, the hot deformation behavior of graphene/copper composites was investigated by isothermal compression tests at deformation temperatures of 700~850 °C and strain rates of 0.01~10 s−1, and a constitutive equation based on the Arrhenius model and hot processing map was established. Results demonstrate that the deformation mechanism of the graphene/copper composites mainly involves dynamic recrystallization (DRX), and such DRX-mediated deformation behavior can be accurately described by the established Arrhenius model. In addition, it was found that the strain rate has a stronger impact on the DRX grain size than the deformation temperature. The optimum deformation temperature and strain rate were determined to be 800 °C and 1 s−1, respectively, with which a uniform microstructure with fine grains can be obtained. [ABSTRACT FROM AUTHOR]

Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The effectiveness of oil-in-water (O/W) microemulsion (ME) in enhancing the oxidation and the storage stability of peony seed oil (PSO), its fatty acid mixtures (FAM-1, FAM-2), and α-linolenic acid (ALA) were investigated in this work. Storage stability was assessed by measuring iodine value, acid value, and fatty acid composition under varying temperature conditions devoid of oxygen. Additionally, antioxidant stability of both the oil phase and ME was evaluated by measuring the peroxide value, with oxidation kinetics modeled using the Arrhenius equation to predict shelf life. The results demonstrated that the change of iodine values for PSO, FAM-1, FAM-2 and ALA at 4, and -20 °C for 90 days was not obvious. At 25°C, the ALA content in PSO, FAM-1, FAM-2 and ALA samples decreased by 4.81%, 3.94%, 2.86%, and 0.12% after 90 days. Therefore, low temperature without oxygen environment is more suitable for the storage of oil and fatty acid. Embedding PSO in ME can effectively control the generation rate of peroxides. At 4°C, the shelf life of PSO, FAM-1 and FAM-2 encapsulated in MEs was prolonged by 28.36%, 9.89% and 4.24%, respectively. Thes results confirm that O/W ME can improve the oxidation stability and prolong the storage period of fat-soluble compounds. These findings provide valuable insights into enhancing the oxidative stability of PSO and its fatty acids, thereby facilitating the development of ME products loaded with fatty acids in the future. [ABSTRACT FROM AUTHOR]

In 2018 the first subglacial lake in the Canadian Arctic was proposed to exist beneath the Devon Ice Cap, based on the analysis of airborne radar data. Here, we report a new interpretation of the subglacial material beneath the Devon Ice Cap, supported by data acquired from multiple surface-based geophysical methods in 2022. The geophysical data recorded included 9 km of active-source seismic-reflection profiles, seven transient electromagnetic (TEM) soundings, and 17 magnetotellurics (MT) stations. These surface-based geophysical datasets were collected above the inferred locations of the subglacial lakes and show no evidence for the presence of subglacial water. The acoustic impedance of the subglacial material, estimated from the seismic data, is 9.49 ± 1.92 × 10 6 kg m -2 s -1 , comparable to consolidated or frozen sediment. The resistivity models obtained by inversion of both the TEM and MT measurements show the presence of highly resistive rock layers (1000–100 000 Ω m) directly beneath the ice. Re-evaluation of the airborne reflectivity data shows that the radar attenuation rates were likely overestimated, leading to an overestimation of the basal reflectivity in the original radar studies. Here, we derive new radar attenuation rates using the temperature- and chemistry-dependent Arrhenius equation, and when applied to correct the returned bed power, the bed power does not meet the basal reflectivity threshold expected over subglacial water. Thus, the radar interpretation is now consistent with the seismic and electromagnetic observations of dry or frozen, non-conductive basal material. [ABSTRACT FROM AUTHOR]

The rarely considered fundamental difference between the temperature dependences of the reaction rate and the rate constant is emphasized. The small change in the rate of reactions with high activation energies, contrary to existing ideas, is illustrated. It was shown that the main reason for the deviation between the calculated and experimental rates is the neglect of the temperature dependence of the reagent concentrations during the reaction. It has been shown that the main reason for the deviation between the calculated and experimental rate values is the neglect of the temperature dependence of the reactant concentrations in the course the reaction. The concept of the temperature rate constant is introduced: the change in the rate with a unit change in temperature, i.e., the temperature derivative of the rate constant. It is shown that this characteristic determines the competition between the stages of a complex process under nonisothermal conditions. The law of temperature dependence of the chain process was discovered, and its agreement with experiment was verified. The difference between the self-acceleration of a reaction from an increase in temperature and from the multiplication of active particles is explained. An experimental illustration is provided. The difference between the temperature dependences of the reaction rates in a gas heated from outside before and after the onset of ignition is explained. Based on experimental data, the determining role of the hydrogen atom concentrations in the combustion rate at hundredths of atmospheric pressure and at atmospheric pressure is quantitatively demonstrated. This demonstrates the determining role in combustion of the conversion of a significant part of the enthalpy of the initial reagents into the free-valence energy. [ABSTRACT FROM AUTHOR]

This investigation is devoted to exhibit the thermal damage of skin tissue exposed to a moving heat source. Modelling of the problem is performed by adopting dual phase lag theory of bio heat transfer in context of memory dependent derivative. Laplace transform technique has been adopted to represent the analytical solutions of temperature and thermal damage of skin tissue. Thermal damages to the tissues are calculated by the extent of the denatured protein employing with the Arrhenius equation. In order to predict the significance of memory dependent derivative approach, computational results of temperature and thermal damage are evaluated in the frame of different kernel functions as well as time-delay. For the purpose of exhibiting the attractiveness of the present model, obtained results are compared with the results corresponding to the absence of memory dependent derivative. Also, the impact of the velocity of moving heat source has been precisely investigated on temperature variation and thermal damage of skin tissue using quantitative results. Authors' believe that this study will be helpful to study the thermal treatment of several diseases such as hyperthermia. [ABSTRACT FROM AUTHOR]

Originally, the Arrhenius parameters were used to estimate the rate of chemical reactions. This article aims to develop the optimal temperature to inhibit specific zero-order kinetic reactions. The model extends the use of the Arrhenius equation and heat capacity modeling to derive the optimal temperature solution. Specifically, the Arrhenius equation, which connects temperature to reaction rates, and the heat equation are formulated to create a comprehensive heat accumulation model. Analytical modeling is utilized through a derivative process to provide optimization. According to a case study of carotene oxidation, the derivative solution proposes −1.73 °C and can extend the reaction time by 206,160.29 days compared to a solution with no temperature change. The derivative solution also offers higher advantages in practical application than setting the lowest temperature limit due to the high initial energy requirement. The temperature derivative solution exhibits a global optimum property because of its high heat accumulation and slower kinetic reactions. These slower kinetic reactions can prevent reactant substances from deteriorating, making them valuable for maintaining a chemical's shelf life. The temperature solutions offer valuable insights for devising an effective temperature strategy to inhibit specific chemical processes and verifying the relationship between temperature and heat accumulation with curvature. [ABSTRACT FROM AUTHOR]

Isothermal information is rarely available for the formation of martensite in Fe or Fe alloys due to a very high rate of transformation compared to the rate of heat conduction. Such information has now been extracted for lath martensite in some sets of Fe alloys from available information on ultra-rapid quenching but only at a single temperature for each alloy, related to its two MS temperatures. The temperature dependence could, thus, be studied only on binary sets of alloys. Those results have been applied to mathematical models based on the Arrhenius equation and illustrated with Arrhenius plots. For three sets of binary Fe alloys, a large group of rates came close to the rate of an almost pure and carbon-free Fe-C alloy. It illustrated that Cr, Ni, and Ru in low contents have relatively small effects on the rate of formation of lath martensite in Fe. It also demonstrated that the present measurements have considerable reproducibility. In contrast, a set of Fe-C alloys did not give a straight line in the Arrhenius plot. Using a new mathematical model based on the concept of the Arrhenius equation to express the effect of carbon, it was possible to predict the rate of formation of lath martensite for Fe-C alloys with fixed C content and their temperature dependencies which are not available experimentally due to the very high rate of formation. [ABSTRACT FROM AUTHOR]

This study explores the impact of varying temperatures on the release behavior of Triptorelin Acetate (TA) from a PLGA-based in-situ forming implant (ISFI) and polymer degradation. Formulations were prepared using the in situ forming method in an acetate buffer (pH = 6.8) and then exposed to temperatures of 4 to 60 °C. The drug release and polymeric depot behavior were evaluated using HPLC, SEM, GPC, Rheometer, and pH measurements. A modified Gallagher-Corrigan Model-based mathematical model was applied to fit the in-vitro data, and the activation energy for peptide release in diffusional and erosional phases was calculated using the Arrhenius equation. The results revealed that matrices formed at 37, 45, and 53 °C exhibited a highly porous structure, resulting from rapid phase inversion and surface pore closing. This led to a reduction in TA burst release, observed as 38%, 27%, and 15% at 37 °C, 45 °C, and 53 °C respectively. Conversely, matrices at 4 and 25 °C demonstrated a faster initial release, followed by the formation of dense structures. The accelerated drug release profiles at 45 and 53 °C showed a shortened ultimate drug release duration and a good correlation with the real-time results at 37 °C. Due to the discernible PLGA matrices degradation at different temperatures, biphasic and tri-phasic release patterns were observed. The experimental release results aligned well with the proposed mathematical model, and the drug release kinetic parameters were estimated. Thus, in in-vitro studies, the release medium temperature plays a significant role in the drug-release behavior of ISFIs. [ABSTRACT FROM AUTHOR]

The rise in early-age temperature concrete structures, driven by the exothermic reactions during cement hydration, significantly increases the risk of thermal cracking. To address this issue, the construction industry employs several strategies, including the partial substitution of cement with ground granulated blast furnace slag (GGBS) due to its lower heat of hydration. Accurately predicting the hydration temperature of concrete is critical for preventing thermal cracking. This task becomes more complex, with fluctuating ambient temperatures influencing hydration kinetics and heat dissipation. Previous studies often assume adiabatic or isothermal conditions, thus overlooking the impact of ambient temperature variations. This paper presents an innovative finite element modelling (FEM) approach to simulate the hydration temperature progression in in situ concrete slabs, incorporating the effects of ambient temperature fluctuations. Isothermal calorimetry curves were adjusted using the Arrhenius-based approach to express the cement hydration rate as a function of ambient temperature. The FEM outcomes, validated with semi-adiabatic calorimetry tests, demonstrate the model’s capability to forecast temperature development in in situ concrete under varying ambient conditions. Additionally, the study examines the influence of partial cement replacement with GGBS on thermal behaviour, revealing that while GGBS effectively reduces thermal reactions at higher contents, its efficacy diminishes with rising ambient temperatures.

The significant production of sewage sludge by wastewater treatment plants on a global scale and the lack of correspondence between housing development and the expansion of sanitation infrastructure indicate a genuine concern regarding environmental preservation. This study addresses the crucial issue of effective sewage sludge management and its environmental impact. In the context of searching for new drying methods that optimize energy use and effectively stabilize sewage sludge, this work investigated the drying behavior of sewage sludge from treatment plants in two northern Moroccan cities using a prototype of an indirect forced convection solar dryer. The drying experiments enabled the determination of drying kinetics as well as highlighted the influence of temperature and humidity on the drying rate. The characteristic drying curve (CDC) and its mathematical expression were determined using Van Meel’s formalism. Thermal diffusivity of wastewater sludge during drying was also investigated. Using Fick’s diffusion model, diffusion coefficients ranged between 0.59 × 10-9 m²/s and 1.43 × 10-9 m²/s, demonstrating an increase in effective diffusivity with rising temperature. The Arrhenius equation provided activation energy values of 16.80 kJ/mol for Oujda samples and 19.72 kJ/mol for Nador samples, indicating the effect of temperature on effective diffusivity. A new equation based on the Midilli-Kucuk model was proposed to predict the drying behavior under untested aerothermal conditions, considering drying temperature and the initial dryness. This study offers a comprehensive analysis of the drying kinetics and effective diffusivity of sewage sludge, providing valuable insights for designing large dryers for sludge management in WWTPs. This approach presents an optimal solution for drying and stabilizing sludge, contributing to environmental preservation efforts. [ABSTRACT FROM AUTHOR]

A linear model for predicting the ignition delay time of hypergolic ignition is presented based on thermal diffusion theory. The heat released by the hypergolic reaction is assumed to diffuse through a given length scale while being governed by a heat source in the form of an Arrhenius equation. A linearized approach is used to reach analytical expressions for the ignition delay times, defined when the temperature change at the reactants interface drastically increases, diverges, or tends toward infinity. Ignition delay times for three different geometries, cartesian, cylindrical, and spherical, are derived and compared. The results show that, for spherical coordinates, the ignition depends on a critical condition, which is based on material and chemical properties and geometry. A prediction of the ignition condition for all cases where one of the reactants is a droplet/particle is given. The ignition process is analyzed based on non-dimensional parameters in order to understand the behavior of the temperature change during ignition. The results obtained are consistent with results presented in the literature. In addition, a prediction for ignition delay times is provided. [ABSTRACT FROM AUTHOR]

When heated rapidly, glasses often devitrify heterogeneously, i.e., by a softening front that originates at the surface of an amorphous film. Yet the fundamentals of this devitrification regime are not completely understood; depending on experimental conditions, the reported front propagation distances differ by an order of magnitude. Using a high-resolution fast scanning calorimetry technique, we have investigated the softening of glassy methylbenzene films with thicknesses between 30 and 1400 nm. We confirm first that, in all films, the devitrification process begins with the formation of a softening front that propagates through the films over distances of ∼50 nm and that the front propagation kinetics at this stage follow an Arrhenius law. However, we also show that, in films with thicknesses above 165 nm, the front propagation does not terminate with the onset of bulk softening. Specifically, increasing the films' thicknesses above 165 nm yields sharp, clearly discernible endotherms that precede the bulk softening endotherms and that are consistent with a two-fold increase in the enthalpic barrier to front propagation at a well-defined critical temperature. We term this phenomenon "Arrhenius discontinuity" and use reaction rate and continuum front dynamics theories to explain its origins and the physical nature of the resulting distinct heterogeneous devitrification processes. Finally, we discuss the findings in the context of recent theoretical, computational, and experimental studies of heterogeneous devitrification by other research groups. [ABSTRACT FROM AUTHOR]

Exploring the sealing stability of different media to plasma-sprayed refractory Al 2 O 3 –13%TiO 2 ceramic coatings is of guiding significance for rational application. Thus, the protective performance of commonly used organic and inorganic sealing agents under different environmental temperatures in chloride ion-containing solutions was investigated in this paper. Firstly, the corrosion resistance of each sample at different temperatures was characterized by potentiodynamic polarization studies. Then the effect of solution temperature was analyzed by Arrhenius equation. Moreover, the mechanism of solution temperature influence was discussed via electrochemical impedance spectroscopy, aiming to provide guidance on the selection of sealing agent types for different environments. The results indicated that both sealing agents provided corrosion resistance far beyond that of the as-sprayed coating at different temperatures. However, as the temperature increased, despite the stable behavior of the inorganic sealing coating itself, the organic sealing agent exhibited a more stable application effect in corrosion resistance, even at 80 °C, it can still show a corrosion current density in the order of 10−8 A cm−2. [ABSTRACT FROM AUTHOR]

• The Arrhenius-type constitutive model for the rare-earth magnesium alloy WE43 is given. • The applicability of the phenomenological constitutive model in the twinning-rich interval needs to be evaluated more objectively. • The occurrence of twinning changes the local internal stress distribution and thus causes the material parameters to deviate from the linear relationship. • The effect of deformation parameters on the twinning fraction is explained from the perspective of dislocation-twinning interaction. According to a high-temperature compression test of rare earth magnesium alloy (WE43), a strain-compensated constitutive model of the Arrhenius equation based on Zener-Hollomon parameters was established, and the rheological behaviors were predicted. The model exhibited relatively serious prediction distortion in the low-temperature and high-strain rate parameter interval, and its accuracy was still unsatisfactory even after modification by a correction operator considering the coupling of temperature and strain rate. The microstructure characterization and statistical analysis showed that a large number of twinning occurred in the parameter intervals with prediction deviation. The occurrence of twinning complicated the local internal stress distribution by drastically changing the crystal orientation and led to significant fluctuations in the macroscopic strain-stress and hardening curves relative to the rheological processes dominated by the dislocation and softening mechanisms, making the logarithm of the strain rate and stress deviate from the linear relationship. This twinning phenomenon was greatly influenced by the temperature and strain rate. Herein, the influence mechanism on twinning behavior was analyzed from the perspective of the interaction of dislocation and twinning. [ABSTRACT FROM AUTHOR]

A numerical study of the processes of heat and mass transfer in the furnace of a thermogravimetric analyzer was carried out, aimed at improving the accuracy of determining the kinetic characteristics of samples during their thermal transformations in different media. Validation of the model and prognostic estimates were carried out in relation to specially conducted thermogravimetric studies of the conversion of fossil and renewable carbon-containing raw materials in successive processes of decarbonization (combustion) and carbonation (mineralization of ash residue). The application of the study results allows to calculate the actual concentrations of the reagent over the sample uncontrolled by the device during pulsed switching of media and the actual temperatures of the sample during its thermochemical transformations. [ABSTRACT FROM AUTHOR]

Lead-free relaxor ferroelectrics are useful in energy storage applications. In particular, BaTi 2 O 5 -based dielectric materials may have great potential for such applications. In this study, polycrystalline Ba 0.95 Sr 0.05 Ti 2 O 5 - x La (BST2- x La) ceramics were synthesized using a standard solid-state reaction method with as-prepared nanoparticles prepared via a modified Pechini polymeric precursor method. The structural and electrical properties of the BST2- x La ceramics were systematically investigated using a series of measurements. The phase analysis results confirm that La3+ is a donor dopant that replaced Ba2+ sites in the structure, which results in a decrease in oxygen vacancies to maintain charge neutrality. The intrinsic electronic conduction mechanism for electrical conductivity was evaluated from the fitted activation energy based on the Arrhenius equation. The relaxor ferroelectric behaviour and energy storage density and efficiency are improved by the addition of a small amount of lanthanum (<3.6 mol%) because of the charge and ionic radius mismatch in the structure. These results suggest that lanthanum can effectively optimise the relaxor ferroelectrics of BST2- x La ceramics, which have promising potential as energy storage materials. • Pure monoclinic-phase polycrystalline BST2- x La ceramics were synthesized. • La3+ acted as a donor dopant in the structure. • Mechanism of intrinsic electronic conduction in the ceramics was deduced. • La3+ could optimise the relaxor ferroelectric properties of BST2- x La ceramics. • The energy storage density and efficiency were improved at small values of x. [ABSTRACT FROM AUTHOR]

Corrosion resistance is the critical in-pile property for developing new Zircaloy cladding. As a new Zircaloy developed by China General Nuclear Power Corporation, CZ will be used as fuel rod cladding. This study is devoted to investigating the corrosion behavior of CZ. A two-stage Arrhenius equation is proposed to model the corrosion rate. A total of 1,510 measurement data points taken from 151 fuel rods irradiated for 1-4 cycles were used to develop the corrosion model. The burnup of these fuel rods ranges from 13.7 MWd/kgU to 55.9 MWd/kgU. The mean value and standard deviation of P-M (predicted value minus measured value) are 0.54 and 3.65 microns, respectively, and the mean value and standard deviation of P/M (predicted value divided by measured value) are 1.09 and 0.34 microns, respectively. P-M and P/M increase with the local burnup. When the burnup is greater than 40 MWd/kgU, the mean values of P-M and P/M are 6.2 and 1.20 microns, respectively; on the other hand, the prediction of the proposed model is more conservative in high burnup. In the typical case in which the average burnup reaches 57 MWd/kgU, the oxide thickness of CZ cladding is much less than 30 microns, whereas the oxide thickness of Zr-4 cladding is approximately 80 microns, and this manifests that CZ cladding possesses excellent performance in corrosion resistance. [ABSTRACT FROM AUTHOR]

The Arrhenius equation is generally adopted for the application of accelerated aging in laboratory tests, and activation energy is one of the important parameters in the equation. In most cases, activation energy was determined by obtaining a series of viscosity data at different temperature, which was a complex process. Therefore, this study aimed to analyze the correlation between activation energy for viscous flow (Eη) and molecular characteristics as well as rheological properties and obtain easily measurable properties that can be used to predict Eη. In this study, nine base asphalt binders were subjected to accelerated aging, and their viscosity, rheological properties, and molecular weight distribution were tested. Small molecule size (SMS) content was the most strongly correlated parameter with Eη for unaged asphalt binder compared with medium molecule size (MMS) content and large molecule size (LMS) content from the result of gray relation analysis. The correlation further weakened after considering aging, which indicated that the change in molecular distribution of asphalt binder may not be the decisive parameter in determining the change in Eη of asphalt binder. Single regression analysis showed a significant correlation between rheological performance parameters and Eη. It was feasible to predict Eη based on the failure temperature and obtain the modified Arrhenius equation. The modified equation could be used to calculate the accelerated aging factor and obtain the aging asphalt and accurate aging status of asphalt binders. By verification, the average error in predicting the Eη of the asphalt binder using the modified equation was less than 5%. [ABSTRACT FROM AUTHOR]

When analyzing materials non-isothermally using the Arrhenius equation under linear heating, a temperature integration is necessary. While the frequency factor in this equation is typically assumed to be constant, it can actually vary with temperature for certain solid-state reactions. The resulting temperature integral, known as the Arrhenius or general temperature integrals, usually have no analytical solutions. Therefore, special functions and approximation functions are often used to estimate them. In this particular study, new rational approximations for the Arrhenius and general temperature integrals were derived through the expansion of the incomplete gamma function. Two sets of these rational approximations, which exhibit excellent accuracy, are presented. One set of approximations for the Arrhenius integral matches the widely used Senum and Yang's approximations, while the other set, which offers even greater accuracy, has not been previously reported. An obtained rational approximation has been utilized to simulate the thermal degradation of a commercially available PMMA, illustrating a practical application example. [ABSTRACT FROM AUTHOR]

The study investigates the transient dynamics of a third-grade fluid, capable of undergoing exothermic reactions, in a two-dimensional rectangular micro-channel. The combined effects of the adverse pressure gradients and electro-osmotic forces constitute the primary flow drivers. In addition to exothermic reactions, the system if also subjected to joule heating and convective cooling at the micro-channel boundaries. Newton's law of cooling and Arrhenius kinetics are employed to model the boundary-cooling and exothermic-reactions respectively. The temperature-dependent fluid viscosity is modelled via a Nahme-type law. It is assumed that the area in between the micro-channels is a porous material with constant permeability. Computational solutions (implemented on the MATLAB software) are employed for the non-homogeneous partial differential equations for temperature and velocity. These computational solutions are developed from efficient, convergent, and unconditionally stable, semi-implicit finite difference methods. In contrast, the linearized Poisson–Boltzmann equation is solved analytically. The sensitivity of the field variables to variations in the various flow parameters are explored graphically and discussed qualitatively. [ABSTRACT FROM AUTHOR]

Self-diffusion in amorphous germanium is studied at temperatures between 325 and 370 °C utilizing amorphous isotopically controlled germanium multilayer structures. The isotope multilayer is epitaxially grown on a single crystalline germanium-on-insulator structure by means of molecular beam epitaxy and subsequently amorphized by self-ion implantation. After heat treatment, the diffusional broadening of the isotope structure is measured with time-of-flight secondary ion mass spectrometry. The temperature dependence of self-diffusion is accurately described by the Arrhenius equation with the activation enthalpy Q = (2.21 ± 0.12) eV and pre-exponential factor D 0 = (2.3 2 − 2.10 + 20.79 ) cm2 s−1. The activation enthalpy equals the activation enthalpy of solid phase epitaxial recrystallization (SPER). This agreement suggests that self-diffusion in amorphous germanium is similar to SPER, also mainly mediated by local bond rearrangements. Classical molecular dynamics simulations with a modified Stillinger–Weber-type interatomic potential yield results that are consistent with the experimental data and support the proposed atomic mechanism. [ABSTRACT FROM AUTHOR]

The effects of different hot air speeds and temperatures on the drying characteristics of half-ripe rice paper were investigated by hot air convection drying experiments. The thin-layer drying experiments were carried out at three different combinations of air speeds of 1.97 m/s, 3.00 m/s, and 3.90 m/s and temperatures of 85 °C, 100 °C and 115 °C. The results show that among the 10 drying kinetic models selected, the Modified Page model is the most suitable model to describe the drying characteristics of the thin layer of half-ripe rice paper; the whole drying process exists obvious ascending, constant and descending processes; the effective moisture diffusion coefficient of half-ripe rice paper is in the range of 1.52656 × 10−9 m2/s–3.15816 × 10−9 m2/s, whose size increases with the increase of the hot wind speed and temperature. Its magnitude increases with the increase of wind speed and temperature; the drying activation energy of half-ripe rice paper is 6.55 kJ/mol calculated by Arrhenius equation. [ABSTRACT FROM AUTHOR]

The ceramic compound CuFe2O4 was synthesised via conventional high-temperature solid-state reaction route. The structural study of the compound was done using X-ray diffraction technique. The preliminary structural study was performed using POWD software and a tetragonal structure was suggested. The Rietveld refinement of XRD (X-ray Diffraction) data was carried out using FullProf software and the refined lattice parameters were obtained as a = 5.80030 Å and c = 8.69400 Å with high tetragonality ratio. The crystallite size and lattice strain were calculated using Williamson–Hall (W-H) plot. The temperature and frequency dependent electrical properties of this compound are analysed using complex impedance technique. The impedance and modulus study of the compound showed the contribution of intra-grain effect to the overall electrical response. The studied ceramic possessed a non-Debye-type relaxation mechanism. The bulk resistance decreased with the increase in temperature, thus showing negative temperature coefficient of resistance behaviour. Modulus and conductivity study showed the evidence of conduction via hopping mechanism inside the material. Frequency-dependent AC conductivity followed Jonscher's universal power law. The Arrhenius equation was fitted with the temperature-dependent AC conductivity at different frequencies, and activation energies were determined to understand the charge species involved in the conduction mechanism. [ABSTRACT FROM AUTHOR]

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