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To target development of bioelectrochemical systems, we developed an advanced microfluidic method to identify reaction bottlenecks in the metabolic activity of a pure‐culture Geobacter sulfurreducens electroactive biofilm (EAB). The microfluidic system was devised to include perpendicular flow orientation for improved boundary layer uniformity and was combined with an embedded 3‐electrode system to accurately apply a constant potential during the entire experimental duration which lasted se. A 3‐sensor temperature control system provided the basis of accurate temperature pulsing, which modified the EAB metabolic activity over short time intervals relative to the bacterial doubling rate. The system, together with the unique ability to control hydrodynamic, electrochemical, and thermal conditions, was used as the basis for an Arrhenius approach to obtain activation energy barrier values at different growth times, acetate concentrations, and flow rates. The results indicated that bottlenecks in the overall metabolic activity after 1 month of growth time were related to electron transfer through extracellular cytochrome c. After the EAB further matured to 4 months old, the bottleneck appeared to switch to enzyme‐driven acetate oxidation. Based on this hypothesis, we observed after 4‐months, that strong increases in effective enzyme concentration were primarily obtained by increasing flow rate, and secondarily by increasing acetate concentration [ABSTRACT FROM AUTHOR]

The Arrhenius energy of activation of unfolding Ea unfolding and Gibbs free energy of unfolding ΔG unfolding have been calculated utilizing DSC differential scanning calorimetry for 4 mAbs (1 biosimilar) in 3 formulations. DSC derived ΔTm melting temperature changes for each mAb domain (CH2, Fab, CH3) at calorimetric scan rates at 60 °C, 90 °C, 150 °C and 200 °C / hr. were utilized to calculate the kinetic Ea unfolding. The DSC derived Ea trend with observed aggregate formation and can be used to predict%HMW formation post 9-month storage at 5 °C and 40 °C for all formulations analyzed. Additionally, thermodynamic ΔG unfolding energies were also derived (Tm, ΔCp and ΔH measurements) for each mAb at every scan rate to observe scan rate dependence of ΔG and for extrapolation to 0 °C/hr. (to report ΔG at true equilibrium conditions). Both derived thermodynamic ΔG and kinetic Ea energies were combined to build full energetic landscapes for mAb unfolding and aggregation. Statistical multivariate analysis of kinetic (Ea CH2, Ea Fab, Ea CH3) energies, thermodynamic (ΔG 5 ° C and ΔG 40 ° C) energies and in-silico modeled surface properties was also performed. Analysis revealed key significant parameters contributing to aggregation. These parameters were utilized to build predictive aggregation models for 25 mg/mL mAb formulations stored 9-months at 5 °C and 40 °C. [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]

The objective of this study is to assess, characterize, and forecast the aging effects on the mechanical properties of a vegetable‐based polyurethane foam (PUF) derived from castor oil under elevated relative humidity conditions and at two distinct load orientations (aligned with the expansion direction and perpendicular to it). Ten specimens were subjected to temperatures of 60, 75, and 90°C, along with a relative humidity of 90%, for a duration of up to 60 days. Compression tests, following ASTM D1621‐16 standards and supplemented by 3D digital image correlation, revealed nearly isotropic behavior with marginally lower compression strength in the expansion direction. On the other hand, the strength of the foams at 90°C was higher in that direction. This led to a smaller activation energy (Ea) in this property, which ended up showing a shorter lifespan prediction considering the strength retention in this direction. The stiffness values were proportionally more similar in both directions than the strength ones and this was observed in the Ea for those curves. In contrast to several other foams and polyurethanes, the one examined in this study exhibited consistently higher Ea values for its mechanical properties, particularly in the transverse direction to expansion, surpassing 94 kJ/mol. This indicates a robust diffusion and chemical stability, suggesting its potential for prolonged utilization compared to conventional oil‐based foams. A prediction was made that this foam would lose 50% of its stiffness and strength in around 9.8 and 9.5 years at 20°C, respectively, considering the directions more sensitive to the aging process. This research offers valuable insights for predicting lifespan based on operating temperatures and property retention needs, contributing to the advancement of sustainable materials in structural applications. Highlights: Fifty specimens investigated for each of two directions.Evaluation of vegetable‐based PUF aging process unveils density changes.Unique behavior noted: different Ea values for each direction.High Ea values indicate enhanced mechanical stability over oil‐based foams.Lifespan prediction enhances material application prospects. [ABSTRACT FROM AUTHOR]

This study aims to determine the shelf life of "hiwan tahu" based on changes in Total Plate Count (TPC), pH, water content, and αw. This research was carried out by storing the samples at three different temperatures, including 5℃, 27℃, and 40℃. The initial characteristic and quality degradation of "Hiwan Tahu" during storage were determined by TPC, pH, water content, and αw tests. Observations were carried out every 3 hours until the 12th hour for storage at 40℃, every 24 hours until the 96th hour at 27℃, and every 48 hours until the 192nd hour for storage at 5℃. Shelf life was determined using the ASLT method with the Arrhenius model. Data were analyzed by Microsoft Excel 2016 by presenting data in a scatter diagram, selecting the reaction order based on the higher R², determining the Arrhenius equation using a chart with a trendline, and calculating shelf life using Excel formulas and functions. The results showed that quality decrease of "hiwan tahu" during storage, including an increase in TPC, pH, water content, and *x value. The shelf life of "hiwan tahu" was determined based on the critical parameter of TPC with the smallest Energy Activation (Ea). The shelf life of "hiwan tahu," according to the TPC parameter, is 68.54 days if stored at -18℃, 16.27 days if stored at 5℃, and 5.05 days if stored at 27℃. The rate of change in "hiwan tahu" quality increases with high temperature and storage time. [ABSTRACT FROM AUTHOR]

This study investigated the pyrolysis properties and kinetic behavior of Ermenek (Konya, Turkey) lignite. For this purpose, lignite was carbonized at 500°C and different heating rates (5, 10, 15, and 20°C/min). Proximate, elemental, XRF, and TGA-DTA lignite and chars were performed. Thermal analyses were performed at a heating rate of 10°C/min from room temperature to 1000°C and an inert (N2) gas flow of 50 ml/min. Peak temperatures and mass losses were determined from the data obtained from the experiments. By examining the thermogram curves, three different temperature regions depended on moisture loss, the release of volatile matter, and fixed carbon combustion. In addition, from these data, kinetic calculations were performed using Arrhenius and Coats-Redfern approaches, and the apparent activation energies were calculated for each region. The activation energy values calculated according to the Coats-Redfern kinetic model are significantly lower than those calculated according to the Arrhenius kinetic model. The highest activation energies calculated were: for Region 1 and Region 2 at 5°C/min heating rate and for Region 3 at 10°C/min heating rate. [ABSTRACT FROM AUTHOR]

Prediction of lyophilized product shelf-life using accelerated stability data requires understanding the temperature dependence of the degradation rate. Despite the abundance of published studies on stability of freeze-dried formulations and other amorphous materials, there are no definitive conclusions on the type of pattern one can expect for the temperature dependence of degradation. This lack of consensus represents a significant gap which may impact development and regulatory acceptance of freeze-dried pharmaceuticals and biopharmaceuticals. Review of the literature demonstrates that the temperature dependence of degradation rate constants in lyophiles can be represented by the Arrhenius equation in most cases. In some instances there is a break in the Arrhenius plot around the glass transition temperature or a related characteristic temperature. The majority of the activation energies (E a), which are reported for various degradation pathways in lyophiles, falls in the range of 8 to 25 kcal/mol. The degradation E a values for lyophiles are compared with the E a for relaxation processes and diffusion in glasses, as wells as solution chemical reactions. Collectively, analysis of the literature demonstrates that the Arrhenius equation represents a reasonable empirical tool for analysis, presentation, and extrapolation of stability data for lyophiles, provided that specific conditions are met. [ABSTRACT FROM AUTHOR]

In this paper, a methodology is proposed for studying the current collapse effects of Gallium Nitride (GaN) power diodes and the consequences on the dynamic on-resistance (RON). Indeed, the growing interest of GaN based, high frequency power conversion requires an accurate characterization and a deep understanding of the device's behaviour before any development of power converters. This study can ultimately be used to model observed trap effects and, thus, improve the equivalent electrical model. Using an in-house circuit and a specific experimental setup, a current-collapse phenomenon inherent to gallium nitride semiconductor is studied on planar 650 V—6 A GaN diodes by applying high voltage stresses over a wide range of temperatures. With this method, useful data on activation energy and capture cross section of electrical defects linked to dynamic RON are extracted. Finally, the origins of such defects are discussed and attributed to carbon-related defects. [ABSTRACT FROM AUTHOR]

The temperature sensitivity of soil processes is of major interest, especially in light of climate change. Originally formulated to explain the temperature dependence of chemical reactions, the Arrhenius equation, and related Q10 temperature coefficient, has a long history of application to soil biological processes. However, empirical data indicate that Q10 and Arrhenius model are often poor metrics of temperature sensitivity in soils. In this opinion piece, we aim to (a) review alternative approaches for characterizing temperature sensitivity, focusing on macromolecular rate theory (MMRT); (b) provide strategies and tools for implementing a new temperature sensitivity framework; (c) develop thermal adaptation hypotheses for the MMRT framework; and (d) explore new questions and opportunities stemming from this paradigm shift. Microbial ecologists should consider developing and adopting MMRT as the basis for predicting biological rates as a function of temperature. Improved understanding of temperature sensitivity in soils is particularly pertinent as microbial response to temperature has a large impact on global climate feedbacks.

The encapsulates of carrot waste oil extract improved the antioxidant properties of durum wheat pasta. The aim of this research was to study the kinetics of carotenoids degradation in the freeze-dried (FDE) and spray-dried (SDE) encapsulates of carrot waste extract during storage at four different temperatures (+4, +21.3, +30, +37 °C) up to 413 days by HPLC. Carotenoids levels decreased as a function of time and temperature, following zero-order kinetics. At 4 °C carotenes were stable for at least 413 days, but their half-lives decreased with increasing temperatures: 8–12 months at 21 °C; 3–4 months at 30 °C; and 1.5–2 months at 37 °C. The freeze-drying technique was more effective against carotenes degradation. An initial lag-time with no or very limited carotenes degradation was observed: from one week at 37 °C up to 3 months (SDE) or more (FDE) at 21 °C. The activation energies (Ea) varied between 66.6 and 79.5 kJ/mol, and Ea values tended to be higher in FDE than in SDE. [ABSTRACT FROM AUTHOR]

The encapsulates of carrot waste oil extract improved the antioxidant properties of durum wheat pasta. The aim of this research was to study the kinetics of carotenoids degradation in the freeze-dried (FDE) and spray-dried (SDE) encapsulates of carrot waste extract during storage at four different temperatures (+4, +21.3, +30, +37 °C) up to 413 days by HPLC. Carotenoids levels decreased as a function of time and temperature, following zero-order kinetics. At 4 °C carotenes were stable for at least 413 days, but their half-lives decreased with increasing temperatures: 8–12 months at 21 °C; 3–4 months at 30 °C; and 1.5–2 months at 37 °C. The freeze-drying technique was more effective against carotenes degradation. An initial lag-time with no or very limited carotenes degradation was observed: from one week at 37 °C up to 3 months (SDE) or more (FDE) at 21 °C. The activation energies (Ea) varied between 66.6 and 79.5 kJ/mol, and Ea values tended to be higher in FDE than in SDE.

Summary: Understanding biological temperature responses is crucial to predicting global carbon fluxes. The current approach to modelling temperature responses of photosynthetic capacity in large scale modelling efforts uses a modified Arrhenius equation.We rederived the modified Arrhenius equation from the source publication from 1942 and uncovered a missing term that was dropped by 2002. We compare fitted temperature response parameters between the correct and incorrect derivation of the modified Arrhenius equation.We find that most parameters are minimally affected, though activation energy is impacted quite substantially. We then scaled the impact of these small errors to whole plant carbon balance and found that the impact of the rederivation of the modified Arrhenius equation on modelled daily carbon gain causes a meaningful deviation of c. 18% day−1.This suggests that the error in the derivation of the modified Arrhenius equation has impacted the accuracy of predictions of carbon fluxes at larger scales since > 40% of Earth System Models contain the erroneous derivation. We recommend that the derivation error be corrected in modelling efforts moving forward. [ABSTRACT FROM AUTHOR]

Performances of rotational shear rheometers are sometimes limited to measuring low viscosity at high temperatures of water-based polymer solutions. These limitations are typically due to the instrument resolution, sample inertia, and volumetric effects. Moreover, such measurements are not possible for temperatures exceeding 80 °C because of evaporation phenomena leading to a distortion of the value. The working principle of rheometers suitable for measuring viscosity above the boiling temperature reduces their sensitivity and limits their use to high-viscosity fluids. Acrylamide-based polymers are viscoelastic complex fluids exhibiting non-Newtonian behavior. Their viscosifying properties are strongly related to their charge density, molar mass, temperature, and salinity. The prediction of their rheological properties at high temperatures is challenging and is often extrapolated with an empiric law, such as Arrhenius equation. To the best of our knowledge, no commercially available rheometers are capable of measuring low viscosity of water-soluble complex fluids at high temperatures. In this work, we investigate a home-made fully automated capillary rheometer that has been developed to give an accurate measurement of viscosity and intrinsic viscosity of polymer solutions. This device is an affordable cost portable apparatus compared with a commercialized rheometer specifically designed for a wide range of viscosities and temperatures for various applications. The intrinsic viscosity has been measured on two acrylamide-based polymers of different chemical compositions using the capillary rheometer at high temperatures. This device has also been explored for measurement of a water-soluble polymer solution viscosity commonly used in enhanced oil recovery applications to limit chemical degradation. [ABSTRACT FROM AUTHOR]

Float currents are steady-state self-discharge currents after a transient phase--caused by anode overhang, polarization, etc.--is accomplished. The float current is measured in this study with a standard test bench for five 18650 cells (Samsung 25R) at potentiostatic conditions while the temperature is changed in 5 K steps from 5 °C to 60 °C. The entire test is performed in about 100 days resulting in 12 measurement points per cell potential for an Arrhenius representation. The float current follows the Arrhenius law with an activation energy of about 60 kJ/mol. The capacity loss measured at reference condition shows a high correlation to the results of float currents analysis. In contrast to classical calendar aging tests, the performed float current analysis enables determining the aging rate with high precision down to at least 10 °C. Returning from higher temperatures to 30 °C reference temperature shows reducing float currents at 30 °C for increasing temperature steps that may originate from an hysteresis effect that has to be investigated in future publications. [ABSTRACT FROM AUTHOR]

The effect of pressure (0.1, 15, 50 and 100 MPa) and temperature (43, 53, 63 °C) on the formation rate (k) of Maillard α-dicarbonyls (absorbance at 294) and melanoidins (absorbance at 420 nm), was studied during hyperbaric storage (HS) of glucose-glycine model solutions (pH 6). While increasing storage temperature increased k values according to the Arrhenius equation (E a ~ 85 kJ mol−1), increasing pressure decreased reaction rates as predicted by the Eyring model (V a ~ 11 mL mol−1). Pressure did not affect reaction temperature sensitivity, indicating no significant mechanism changes under hyperbaric conditions. A combined model predicting the effect of concomitant changes of temperature and pressure on Maillard reaction rate was implemented and validated within and outside (20–25 °C, 20–200 MPa) its building range. Results indicate HS to limit Maillard browning in food, with possible practical applications, and the potential to develop predictive models based on temperature-accelerated HS trials. The capability of hyperbaric storage to impair Maillard reaction rate extends the scope of this multi-tasking technology to the prevention of color alterations due to non-enzymatic browning. The latter is expected to be of industrial relevance in the case of perishable foods affected by this phenomenon, such as thermally-treated milk. In these matrices, the technology could concomitantly guarantee microbiological safety, protein functionalization, and Maillard browning impairment. • The effect of hyperbaric storage (HS) on Maillard reaction kinetics was studied. • Glucose-glycine solutions (pH 6) were selected as model systems and subjected to HS. • HS impaired α-dicarbonyls and melanoidins formation rate according to Eyring equation. • Pressure reduced the Arrhenius frequency factor without affecting activation energy. • A combined Arrhenius-Eyring model was developed to predict Maillard reaction rate. [ABSTRACT FROM AUTHOR]

Methods. An accelerated shelf life test (ASLT) was conducted, and various quality indicators were measured during this time, such as: pH, titratable acidity, colour, total aerobic count (TAC) and sensory analysis. The test was performed on smoothie beverages purchased from Romanian market for 24 days, the samples being stored at three different temperatures: 5°C, 10°C and 15°C. The analysis of the quality parameters showed that the pH, titratable acidity and the measurement of colour suffered a minor value modification, while the TAC number increased as the storage temperature increased. The results of the research were analysed using Arrhenius equation and Q10 Rule. The TAC changes followed an apparent first-order kinetics, their rates and activation energies were estimated from the experimental data (as a plot of temperature vs time). The fruit smoothies had an estimated shelf life of about 57 days (at 5°C) and 50 days (at 7°C) using the Arrhenius equation and an estimated shelf life about 49 days using the Q10-Rule, after extrapolating the data to real temperature conditions. [ABSTRACT FROM AUTHOR]

For asphalt concrete preparation in laboratory mix-design operations, bitumens are usually mixed with micrometer-sized particles (filler), sand and centimeter-sized crushed stones in a gyratory press at a temperature of about 140–155 °C depending on the bitumen viscosity, until adequate homogenization and compaction take place (air voids optimum). This requires energy consumption. To minimize it, the process needs to be optimized and is usually made empirically. The aim of this manuscript is to gain a comprehension of the physico-chemical mechanisms involved in the process by exploring: (i) the rheological properties (viscosity, activation energy) of a neat and RTFOT-aged bitumen, in presence and in absence of a filler, (ii) the volumetric and resistance behavior under the compaction in a standard Gyratory Compactor (GC) of their blends with aggregates and (iii) the mechanical properties (Indirect Tensile Strength, compression and tensile deformation) of the final products. Correlations between activation energy and pre-exponential factor of the viscosity on a side, and between viscosity, workability and final mechanical properties on the other side allowed to provide a rational interpretation of the physico-chemical processes involved in the framework of the physics of complex fluids. The scientific clues will be of help in optimizing the workability in asphalt concretes productions with obvious repercussions in terms of energy savings, useful for economic and environmental issues. [ABSTRACT FROM AUTHOR]

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Steelmaking slag (SS) is one of the largest generation waste in the integrated and semi-integrated plants, but it has application restrictions due to its high expansibility. To overcome these constraints, this research had as its main objective the reactions is kinetics parameters estimation that result in the expansion of SS using the Arrhenius global equation. It was obtained 12.5 kJ/mol for activation energy and 260.42% for the pre-exponential factor. It was also noted that the temperature significantly impacts the final expansion values, increasing them exponentially. Furthermore the time of expansion of the slag obey an asymptotic equation (Exp = a - b.ct) whose results presented initially having a large expansion velocity, which tends to zero at times very long when the material has stabilized.

Abstract: Traits‐based approaches in microbial ecology provide a valuable way to abstract organismal interaction with the environment and to generate hypotheses about community function. Using macromolecular rate theory (MMRT), we recently identified that temperature sensitivity can be characterized as a distinct microbial trait. As temperature is fundamental in controlling biological reactions, variation in temperature sensitivity across communities, organisms, and processes has the potential to vastly improve understanding of microbial response to climate change. These microbial temperature sensitivity traits include the heat capacity ( Δ C P ‡), temperature optimum (Topt), and point of maximum temperature sensitivity (TSmax), each of which provide unique insights about organismal response to changes in temperature. In this meta‐analysis, we analyzed the distribution of these temperature sensitivity traits from bacteria, fungi, and mixed communities across a variety of biological systems (e.g., soils, oceans, foods, wastewater treatment plants) in order to identify commonalities in temperature responses across these diverse organisms and reaction rates. Our analysis of temperature sensitivity traits from over 350 temperature response curves reveals a wide distribution of temperature sensitivity traits, with Topt and TSmax well within biological relevant temperatures. We find that traits vary significantly depending on organism type, microbial diversity, source environment, and biological process, with higher temperature sensitivity found in fungi than bacteria and in less diverse systems. Carbon dioxide production was found to be less temperature sensitive than denitrification, suggesting that changes in temperature will have a potentially larger impact on nitrogen‐related processes. As climate changes, these results have important implications for basic understanding of the temperature sensitivity of biological reactions and for ecological understanding of species’ trait distributions, as well as for improved treatment of temperature sensitivity in models. [ABSTRACT FROM AUTHOR]

We report the activation energy, ΔEa, for the quantum yield in thermally assisted photoelectron emission (TAPE) under 210-nm-wavelength light irradiation, and the associated X-ray photoelectron spectroscopy (XPS) results. Samples were cleaned only in acetone and scratched in air, water, methanol, ethanol, acetone, benzene, and cyclohexane. Glow curves, describing the temperature dependence of photoelectron emission (PE) quantum yield (emitted electrons/photon), Y, were obtained. A simple method of determining ΔEa using Y, called YGC, at seven temperatures up to 353 °C, for the same Y glow curve, was proposed. The ΔEa obtained using this method was almost the same as that obtained from Y for seven stationary temperatures (YST). For scratched samples, the TAPE was measured over two cycles of temperature increase and subsequent decrease (Up1, Down1 and Up2, Down2 scans) in the 25-339 °C range, and ΔEa was obtained from YGC. The Arrhenius plot was approximated by a straight line, although a convex swelling peak appeared in the Up1 scan. ΔEaUp1 was in the 0.212-0.035 eV range, depending on the environment in which scratching was performed; ΔEaUp1 for water was much higher than that for acetone. This was explained in terms of the mode of the acid-base interaction between the liquid molecules and the hydroxyl group of Fe-OH. The values of ΔEaDown1, ΔEaUp2, and ΔEaDown2 were in the 0.038-0.012 eV range. The total count of electrons emitted during the Up1 and Up2 scans was found to decrease with increasing ΔEaUp1 and ΔEaUp2, respectively. ΔEaUp2 was found to increase with increasing presence of the FeO component in the analyzed Fe oxides. The convex swelling peak was attributed to the removal of carbon materials from the scratched surface and the effect of the increased electron density of the surface hydroxyl group of FeOH under the light irradiation. [ABSTRACT FROM AUTHOR]

For intermediate temperature solid oxide fuel cells (IT-SOFCs), (Bi 2 O 3 ) 1− x − y (Sm 2 O 3 ) x (Yb 2 O 3 ) y ternary systems ( x =0.01 and y = 0.11), ( x =0.05 and y = 0.07), ( x =0.07 and y =0.05), and ( x =0.11 and y =0.01) as electrolytes have been fabricated at different temperatures (700, 750, and 800 °C) by solid state ceramic technique (SST). The characterization of the samples has been performed by X-ray powder diffractometer (XRD), scanning electron microscopy (SEM), four point-probe method (FPPM), X-ray energy diffraction spectroscopy (EDX), and differential thermal analysis (DTA). XRD measurements have shown that only the samples (Bi 2 O 3 ) 1- x-y (Sm 2 O 3 ) x (Yb 2 O 3 ) y ( x =0.01, y =0.11 synthesized at 700, 750, and 800 °C) and ( x =0.05, y =0.07 synthesized at 800 °C) have stable fluorite type face centered cubic (FCC) δ-phase. SEM images have shown the morphology of the stable samples. The conductivity and the operation temperature region of the samples have been determined from Arrhenius curves obtained from the FPPM measurements data and they vary from 1.83 to 9.95×10 −1 S cm −1 . Moreover, activation energy of the samples have been calculated by means of Arrhenius curves of the samples and relationships between them and the conductivity of the samples have been investigated in detail. The results obtained from XRD and FPPM measurements were confirmed by the DTA measurements. [ABSTRACT FROM AUTHOR]

In this paper, Schottky diodes, consisting of an n-doped 4H–silicon carbide substrate, and molybdenum and molybdenum nitride thin-film metallization, are presented. By the variation of the nitrogen amount in the molybdenum nitride thin films, we successfully manage to adjust the effective Schottky barrier height in the range 0.68–1.03 eV at room temperature. In addition, the temperature dependence of the Schottky barrier height can be influenced by the nitrogen fraction used during sputter deposition. The electrical behavior of the junctions is analyzed using current over voltage ( $I/V$ ) and capacitance over voltage ( $C/V$ ) measurements in a temperature range of 25 °C–300 °C and 25 °C–175 °C, respectively. The characteristics are evaluated, and typical diode parameters are extracted. [ABSTRACT FROM AUTHOR]

The activation energies of Chlorinated isobutylene-co-isoprene (CIIR) and Brominated isobutylene-co-isoprene (BIIR) were determined after thermo-oxidation in the 23–100 °C temperature range. Fourier Transform Infrared (FTIR) spectroscopy was used to follow carbonyl growth and aid in the identification of oxidative species along with 1 H Nuclear Magnetic Resonance (NMR). Two thermo-oxidative processes at high (100–80 °C) and at low temperatures (60–23 °C) including a transition zone at 70 °C were identified. Halobutyl oxidation is occurring at the exomethylene microstructure and residual isoprene units during low temperature aging while the isobutylene sequences undergo oxidation at higher temperatures. Loss of bromine radical is quicker than chlorine, which is in line with their inherent bond strengths and agrees with the lower activation energy for BIIR (22 kJ/mol) compared to CIIR (52 kJ/mol) at low temperatures. Chain cleavage reactions dominate at low temperatures and a reaction pathway showing loss of halogen and the formation of macroradicals which undergo oxidation has been proposed. At higher temperatures (80–100 °C), chain crosslinking reactions become more numerous causing a substantial increase in activation energies for halobutyl in comparison to butyl rubber. [ABSTRACT FROM AUTHOR]

• Recommendations are provided for kinetic analysis of thermal polymerization. • Main focus is on analysis of DSC measurements. • Multi-step nature of polymerization kinetics is emphasized. • Model-fitting, isoconversional, and deconvolution analyses are discussed. • Specific advices are offered for efficient usage of each analysis. The present recommendations have been developed by the Kinetics Committee of the International Confederation for Thermal Analysis and Calorimetry (ICTAC). The recommendations provide guidance on kinetic analysis of thermal polymerization, which incorporates both linear and crosslinking polymerization (curing). The focus is on treating the kinetics as measured by differential scanning calorimetry (DSC). The recommendations discuss basic reaction mechanisms and emphasize the multi-step nature of the polymerization kinetics. An overview of mechanistic and phenomenological models is provided for polymerization controlled by reaction kinetics and diffusion. Three different approaches to evaluation of kinetic parameters (activation energy, preexponential factor, reaction model) for individual steps are considered. These approaches comprise model-fitting, isoconversional, and deconvolution analyses. Practical advices are offered for effective usage of each approach. Attention is paid to the typical problems and to the ways of addressing them. The recommendations are intended to assist with efficiently conducting kinetic analysis and interpreting its results. [ABSTRACT FROM AUTHOR]

The inactivation of catalase during spray-drying over a range of outlet gas temperatures could be closely represented by the Arrhenius equation. From this an activation energy for damage to the catalase could be calculated. The close fit to Arrhenius suggests that the thermally-induced part of inactivation of the catalase during the complex drying and particle-formation processes takes place at constant temperature. These processes are rapid compared with the residence time of the powder in the collecting vessel of the cyclone where dried catalase is exposed to a constant temperature equal to approximately the drying gas outlet temperature. A lower activation energy after spray drying with the ultrasonic nozzle was found than with the 2-fluid nozzle under otherwise identical spray drying conditions. It is feasible that the ultrasonic nozzle when mounted in the lid of the spray dryer heats up toward the drying gas inlet temperature much more that the air-cooled 2-fluid nozzle. Calculation of the Arrhenius activation energy also showed how the stabilizing efficacy of trehalose and mannitol on the catalase varies in strength across the range of drying gas inlet and outlet temperatures examined. [ABSTRACT FROM AUTHOR]

The paper discusses of some issues of thermoanalytical kinetics that have not been addressed in the previously published CTAC kinetic recommendations. Namely the true nonequilibrium degree of conversion, factual and fictional modeling, nucleation-growth exponents, cold crystallization, effect of undercooling, logistic equations, model-free methods, meaning of activation energy, Arrhenius and non-Arrhenius approach, thermal gradients, misfit of Kissinger method and the true meaning of temperature measured during rapid temperature changes. Insensitiveness of traditional kinetic model discrimination is attributable to the equivalency of exploited plots (from 1/ T to divergent T —legitimate for a narrow temperature interval) and further smoothing effect due to using logarithm. The most important impact on kinetic data evaluation is a persisting neglect of thermal inertia when evaluating DTA peaks presented on every occasion of real measurements. The majority of 149 references are focused on papers published in Thermochimica Acta. [ABSTRACT FROM AUTHOR]

Knowledge of how biochar impacts soil denitrification kinetics as well as the mechanisms of interactions is essential in order to better predict the nitrous oxide (NO) mitigation capacity of biochar additions. This study had multiple experiments in which the effect of three biochar materials produced from corn stover ( Zea mays L.), ponderosa pine wood residue ( Pinus ponderosa Douglas ex Lawson and C. Lawson), switchgrass ( Panicum virgatum L.), and their corresponding biomass materials (corn stover, ponderosa pine wood residue, and switchgrass) on cumulative NO emissions and total denitrification in soils from two different landscape positions (crest and footslope) were studied under varying water-filled pore space (40, 70, and 90 % WFPS). Cumulative NO emissions were reduced by 30 to 70 % in both crest and footslope soils. The effect of biochars and biomass treatments on cumulative NO emissions and total denitrification were only observed at ≥40 % WFPS. The denitrification enzyme activity (DEA) kinetic parameters, K (half-saturation constant), and V (maximum DEA rate) were both significantly reduced by biochar treatments, with reductions of 70-80 % in footslope soil and 80-90 % in the crest soil. The activation energy ( E) and enthalpy of activation of DEA (Δ H) were both increased with biochar application. The trends in DEA rate constants ( K and V) were correlated by the trends of thermodynamic parameters (activation energy E and enthalpy of activation Δ H) for denitrifying enzyme activity (DEA). The rate constant V/ K evaluated the capacity of biochars to mitigate the denitrification process. Denitrifying enzyme kinetic parameters can be useful in evaluating the ability of biochars to mitigate NO gas losses from soil. [ABSTRACT FROM AUTHOR]

Global change is affecting plant and animal populations and many of the changes are likely subtle and difficult to detect. Based on greenhouse experiments, changes in temperature and rainfall, along with elevated CO2, are expected to impact the nutritional quality of leaves. Here, we show a decline in the quality of tree leaves 15 and 30 years after two previous studies in an undisturbed area of tropical forest in Kibale National Park, Uganda. After 30 years in a sample of multiple individuals of ten tree species, the mature leaves of all but one species increased in fiber concentrations, with a mean increase of 10%; tagged individuals of one species increased 13% in fiber. After 15 years, in eight tree species the fiber of young leaves increased 15%, and protein decreased 6%. Like many folivores, Kibale colobus monkeys select leaves with a high protein-to-fiber ratio, so for these folivores declining leaf quality could have a major impact. Comparisons among African and Asian forests show a strong correlation between colobine biomass and the protein-to-fiber ratio of the mature leaves from common tree species. Although this model, predicts a 31% decline in monkey abundance for Kibale, we have not yet seen these declines. [ABSTRACT FROM AUTHOR]

Variation in resource supply can cause variation in temperature dependences of metabolic processes (e.g., photosynthesis and respiration). Understanding such divergence is particularly important when using metabolic theory to predict ecosystem responses to climate warming. Few studies, however, have assessed the effect of temperature-resource interactions on metabolic processes, particularly in cases where the supply of limiting resources exhibits temperature dependence. We investigated the responses of biomass accrual, gross primary production (GPP), community respiration (CR), and N2 fixation to warming during biofilm development in a streamside channel experiment. Areal rates of GPP, CR, biomass accrual, and N2 fixation scaled positively with temperature, showing a 32- to 71-fold range across the temperature gradient (~7°-24°C). Areal N2-fixation rates exhibited apparent activation energies (1.5-2.0 eV; 1 eV ¼ ;1.6 3 10-19 J) approximating the activation energy of the nitrogenase reaction. In contrast, mean apparent activation energies for areal rates of GPP (2.1-2.2 eV) and CR (1.6-1.9 eV) were 6.5- and 2.7-fold higher than estimates based on metabolic theory predictions (i.e., 0.32 and 0.65 eV, respectively) and did not significantly differ from the apparent activation energy observed for N2 fixation. Mass-specific activation energies for N2 fixation (1.4-1.6 eV), GPP (0.3-0.5 eV), and CR (no observed temperature relationship) were near or lower than theoretical predictions. We attribute the divergence of areal activation energies from those predicted by metabolic theory to increases in N2 fixation with temperature, leading to amplified temperature dependences of biomass accrual and areal rates of GPP and R. Such interactions between temperature dependences must be incorporated into metabolic models to improve predictions of ecosystem responses to climate change. [ABSTRACT FROM AUTHOR]

The activation energies of two poly(isobutylene-co-isoprene) (IIR) copolymers containing 0.9 and 1.85 mol% isoprene were determined under thermo-oxidation conditions from ambient to 100 °C. Transmission Fourier Transform Infrared (FTIR) spectroscopy was used to follow the functional group development. Ketone generation was the dominant oxidative product above 70 °C whereas below this temperature, carboxylic acid formation was prevalent. Non-Arrhenius kinetic behavior was observed due to curvature taking place near 70 °C. The estimated activation energies for the high and low temperature degradation processes were 85–87 kJ/mol and 49 kJ/mol. Test results were interpreted in terms of two competing thermo-oxidative zones, isobutylene and isoprene, the latter operating at low temperatures as shown by isoprene depletion and chain scission reactions. A set of thermo-oxidative reactions for IIR copolymers is proposed comprising allylic and addition reactions at the isoprene unit. [ABSTRACT FROM AUTHOR]

We have investigated the role of temperature in the degradation of GaN High-Electron-Mobility-Transistors (HEMTs) under high-power DC stress. We have identified two degradation mechanisms that take place in a sequential manner: the gate leakage current increases first, followed by a decrease in the drain current. Building on this observation, we demonstrate a new scheme to extract the activation energy ( E a ) of device degradation from step-temperature measurements on a single device. The E a ’s we obtain closely agree with those extracted from conventional accelerated life test experiments on a similar device technology. [ABSTRACT FROM AUTHOR]

An accurate, semi-analytic solution of the Arrhenius temperature integral is the basis for an isoconversion method to extract kinetic parameters of single-step reactions from multiple heating rate experiments in a single iteration. The isoconversion method can be expressed as a finite difference (FD) formula identical in form and function to Kissinger's maximum reaction rate equation or can be differentiated to yield an analytic derivative (AD) formula similar to Ozawa's equation. The FD and AD isoconversion formulae provide identical, model-free activation energies by direct calculation when applied to differential thermal analysis data without the need for recursion as in some standard test methods. A model-dependent frequency factor can be obtained from the FD formula. [ABSTRACT FROM AUTHOR]

Abstract: The thermo-oxidation of poly(isobutylene) (PIB) has been investigated by using accelerated heat aging in the 40–100 °C range and functional group analysis by transmission Fourier Transform Infrared (FTIR) spectroscopy. Time–temperature superposition (TTS) and the Arrhenius approach were used to calculate activation energies. Oxidation product evolution was continuous within the temperature range. PIB displayed excellent TTS and linear Arrhenius behavior leading to an energy of activation (E a) range of 116–125 kJ/mol for the growths of the carbonyl (ketone), hydroxyl and β-lactone groups. The similarity between the E a values strongly suggests that the reactions that they comprise are interrelated, agreeing with the currently accepted oxidation mechanisms of PIB. [Copyright &y& Elsevier]

Sensitive ingredients of food, pharmaceutical products, or bioproducts can be damaged due to inappropriate processing conditions. The knowledge of the kinetics of degradation reactions allows optimizing production processes with regard to the nutritional quality. The essential amino acid lysine is an important nutrient in dairy powders that can be blocked, e.g., due to the Maillard reaction during drying processes. In this study, we showed that lysine loss can be modeled with pseudo-second-order reaction kinetics. The reaction rate constants increased with increasing temperature. At 90 °C, the highest reaction rate constant was found at a water activity of 0.23. This maximum was shifted to higher water activities for lower temperatures. The temperature dependence of the reaction rate constants could be modeled by the Williams-Landel-Ferry equation in the vicinity of the glass transition temperature and in the rubbery state. The glass transition temperature was calculated with the Gordon and Taylor equation. At higher temperatures and water contents, Arrhenius-type behavior was determined. The activation energy E and the pre-exponential factor $$ k_0^{*} $$ of the Arrhenius equation were expressed as a function of the water content. Thus, it is possible to model lysine loss under conditions that are typical of the production of dairy powders as a function of the temperature, water content, and physical state. The established pseudo-second-order reaction kinetics model can be used to minimize lysine loss during the production of milk powder and to ensure a high nutritional quality. [ABSTRACT FROM AUTHOR]

As product-development cycles become shorter and companies demand more rapid achievement of reliability goals, it is becoming more and more important to use quantitative accelerated life tests (ALT) to predict and improve reliability. Today there is an abundance of methods to plan and analyze accelerated tests, but there are also many pitfalls. This paper identifies some major problems and concerns in conducting and interpreting the results of accelerated tests. We identify various pitfalls, such as using an equal unit allocation at all levels of an accelerating variable, using unnecessarily complex testing and data analysis schemes, attempting to predict life from a HALT, using ALT at the system level, not having adequate time-to-failure information, using extreme extrapolation, ignoring the impact of idle time in use-rate acceleration tests, and not understanding interactions between accelerating variables. [ABSTRACT FROM AUTHOR]

Devolatilization behavior of several types of agricultural stalks (sunflower, rice, corn, and wheat) was studied using thermogravimetric system (TG) under nitrogen atmosphere at different heating rates (10, 15, and 20 °C min). Coats&Redfern, Horowitz&Metzger, and Arrhenius non-isothermal kinetic models were applied to calculate the devolatilization kinetic parameters and the devolatilization rate equations have been established. In addition, the kinetic compensation effect (KCE) has also been used to correlate pre-exponential factor ( k) with activation energy ( E) and an existence of the KCE is accepted. TG-FT/IR analyses were applied of the different stalks and FT/IR stack plot used to analyze the devolatilization gas products (CO, CH, HCOOH, CHOH). Infrared vibrational frequencies, micro structure and crystallinity of stalks were investigated by Fourier transform infrared spectroscopy (FT/IR), scanning electron microscope (SEM), and X-ray diffraction analysis (XRD), respectively. [ABSTRACT FROM AUTHOR]

Abstract: A new enzyme homologous to phosphotriesterase was identified from the bacterium Geobacillus stearothermophilus (GsP). This enzyme belongs to the amidohydrolase family and possesses the ability to hydrolyze both lactone and organophosphate (OP) compounds, making it a phosphotriesterase-like lactonase (PLL). GsP possesses higher OP-degrading activity than recently characterized PLLs, and it is extremely thermostable. GsP is active up to 100°C with an energy of activation of 8.0kcal/mol towards ethyl paraoxon, and it can withstand an incubation temperature of 60°C for two days. In an attempt to understand the thermostability of PLLs, the X-ray structure of GsP was determined and compared to those of existing PLLs. Based upon a comparative analysis, a new thermal advantage score and plot was developed and reveals that a number of different factors contribute to the thermostability of PLLs. [Copyright &y& Elsevier]

[Display omitted] • New asymmetrical dioxidothiomorpholinium-morpholinium dicationic ionic liquid. • Electrical conductivities of IL binary solutions in propylene carbonate. • Activation energies of conductivity using Arrhenius, Litovitz and VFT equations. • Electrochemical window increases from 3.9 V at 363 K to 4.8 V at 233 K. A new asymmetrical 1,1-dioxidothiomorpholinium- and morpholinium-based dicationic ionic liquid (4-ethyl-4-[3-(4-ethyl-1,1-dioxidothiomorpholin-4-ium-4-yl)propyl]morpholin-4-ium tetrafluoroborate (EtDTMC 3 EtM·2BF 4)) was synthesized in four stages and characterized by 1H, 13C, 1H,1H–COSY NMR, single X-ray diffraction, XPS spectroscopy and simultaneous thermal analysis. Electrical conductivities of several EtDTMC 3 EtM·2BF 4 solutions in propylene carbonate (PC) were measured in the 298 – 368 K temperature range and analyzed using the Arrhenius, Litovitz, and Vogel–Fulcher–Tammann (VFT) equations. [ABSTRACT FROM AUTHOR]

Abstract: Some aspects of proper linearization of the Boyle–van’t Hoff (BVH) relationship for calculation of the osmotically inactive volume , and Arrhenius plot (AP) for the activation energy are discussed. It is shown that the commonly used determination of the slope and the intercept (), which are presumed to be independent from each other, is invalid if the initial intracellular molality is known. Instead, the linear regression with only one independent parameter () or the Least Square Method (LSM) with as the only fitting LSM parameter must be applied. The slope can then be calculated from the BVH relationship as the function of . In case of unknown (for example, if cells are preloaded with trehalose, or electroporation caused ion leakage, etc.), it is considered as the second independent statistical parameter to be found. In this (and only) scenario, all three methods give the same results for and . AP can be linearized only for water hydraulic conductivity () and solute mobility () while water and solute permeabilities ≡ L p RT and ≡ cannot be linearized because they have pre-exponential factor (RT) that depends on the temperature T. [Copyright &y& Elsevier]

Samples of full‐length glove‐fingers cut from chlorinated and nonchlorinated latex medical examination gloves were aged for various times at several fixed temperatures and 25% relative humidity. Creep testing was performed using an applied stress of 50 kPa on rectangular specimens (10 mm × 8 mm) of aged and unaged glove fingers as an assessment of glove loosening during usage. Variations in creep curves obtained were compared to determine the threshold aging time when the amount of creep became larger than the initial value. These times were then used in various models to estimate shelf lives at lower temperatures. Several different methods of extrapolation were used for shelf‐life estimation and comparison. Neither Q‐factor nor Arrhenius activation energies, as calculated from 10°C interval shift factors, were constant over the temperature range; in fact, both decreased at lower temperatures. Values of Q‐factor and activation energies predicted up to 5 years of shelf life. Predictions are more sensitive to values of activation energy as the storage temperature departs from the experimental aging data. Averaging techniques for prediction of average activation energy predicted the longest shelf life as the curvature is reduced. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008 [ABSTRACT FROM AUTHOR]

Abstract: An attempt is made to explain why the apparent activation energy of respiration of fresh produce is negative at the higher temperatures of 40–50°C. We assumed that maintenance of respiratory enzyme function was reduced at high temperatures, but the activity of the individual enzymes was not changed. In this study, experiments for testing the assumption were carried out to examine the influence of high temperature (50°C) on the Arrhenius parameters of respiration rate. As a result, for asparagus and broccoli, the apparent activation energy of the respiratory reaction barely changed. However, the pre-exponential factor decreased with increasing exposure time at 50°C. The apparent activation energy is defined as the minimum kinetic energy that reactants must have to form products and the pre-exponential factor reflects the frequency of interaction between reactants. Considering that the respiratory reaction is composed of many different enzyme reactions, the apparent activation energy and pre-exponential factor of the respiratory reaction reflect the activation energy of the enzyme reaction and the concentration of enzyme, respectively, under conditions of enriched oxygen and respiratory substrate. Therefore, the results for asparagus and broccoli in this study support our assumption. Also, a temperature of 50°C is proposed to reduce the quantity of respiratory enzyme, with no affect on the apparent activation energy of enzyme reaction when the produce is heated to 50°C. [Copyright &y& Elsevier]