Temperature Range Research Articles

Influence of hydrogen bonds on state diagrams of cryoprotectant solutions

BACKGROUND: Transformation of state diagrams of cryoprotectant solutions under the influence of weak intramolecular interactions was considered. MATERIALS AND METHODS: Phase states of aqueous glycerol and DMSO solutions within temperature range +25???−150 °?? were studied using method of volumetric scanning tensodilatometry. Temperatures below which hydrogen bonds significantly affect crystallization-melting kinetics of such solutions were determined. RESULTS: Principles for plotting of state diagram for binary solutions with weak intermolecular interaction of the components were set up. The study demonstrates that in such solutions formation of clusters based on ice microcrystals and cryoprotectant occurs. Based on the obtained results, state diagrams for glycerol and DMSO aqueous solutions were plotted. These diagrams include area of cluster phase existence and differ fundamentally from those describing eutectic crystallization. CONCLUSION: Nanostructures occurring in cryoprotectant solutions during their cooling were analyzed. Difference between these structures and classical solid phase eutectics were demonstrated.

An Extensive Review of MR Sensors with Design and Characteristic Evaluation of Three-layered TMR Sensor

Abstract: The reliability and efficacy of sensor-based automated systems have improved due to the proliferation of electric vehicles, renewable sources, and integrated systems in power industries extensively. This has been accomplished by increasing the power density and decreasing the volume of the system. Background: Mathematical estimation and comparative analysis of the physical factors result in massive usage of operational matrices measured using sensors. Magnetic field sensors, used in industries and biomedical applications, have a high level of precision in the evaluation of measurements. In order to extract the measured parameters such as sensitivity, accuracy, operating cost, the linear range of operation, and power utilisation, these sensors adhere to the physical constraints during their nominal working conditions. The characteristics of the aforementioned sensors are enumerated in detail in this article. Objective: This objective is highly focused on providing a comprehensive overview of classification and the properties of Hall-Effect, anisotropic magnetoresistive (AMR), giant magnetoresistive (GMR), and tunnelling magnetoresistive (TMR) sensors. The dissertation on its properties concludes that TMR is more reliable and sensitive in variable operating conditions. Methods: The methods for selecting the sensors for an application are confined to voltage fluctuations and sensitivity. A three-layered TMR sensor with two magnetic layers and an insulator in between is proposed as a significant advancement compared to the literature. The micromagnetic simulation is carried out at room temperature for a three-layered TMR made up of neodymium alloy, magnesium oxide, and cobalt platinum alloy. Conclusion: Based on the studies executed, it is determined that TMR is more sensitive than both conventional and MR sensors. The proposed schematic claims that the higher free layer thickness offers maximum sensitivity with 77% negative magnetoresistance. The reduced coercivity of 1.9Oe is achieved in this combination at a specified temperature range.

Impact of metakaolin on hydration properties of magnesium phosphate cement

The degradation of mechanical properties in magnesium phosphate cement (MPC) is commonly observed under conditions of rapid heat release and high ambient temperature. To mitigate this phenomenon, the incorporation of metakaolin has been investigated as a means to reduce the hydration heat of MPC and enhance its mechanical properties at elevated temperatures. Experimental findings reveal a pronounced influence of metakaolin on the heat flow behavior of MPC. Specifically, the addition of a small fraction of metakaolin (not exceeding 20wt%) leads to an accelerated heat release rate during the initial 0.13hours, followed by a substantial reduction in the heat release rate with further increments of metakaolin. Furthermore, the inclusion of metakaolin significantly improves the mechanical properties of MPC. For instance, a composition comprising 30% metakaolin yields a notable 79.2% increase in strength after 7 days. It is worth noting that temperatures below 400℃ are found to have an adverse impact on the mechanical properties of MPC, whereas a temperature range encompassing 600℃>T>400℃ enhances these properties due to vitrification at high temperatures. Importantly, MPC incorporating metakaolin exhibits superior mechanical performance compared to its metakaolin-free counterpart across all tested temperatures, which can be attributed to the attainment of a denser microstructure facilitated by metakaolin incorporation.

In Ukrainian

The contact wetting is one of the effective methods of studying the adsorption capacity of sorbents. The purpose of the work was to compare the experimentally obtained data on the adsorption capacity of shungite, obtained by the sessile drop method, and the results of modeling the behavior of liquid droplets on heterogeneous surfaces using the Boltzmann lattice method, and to show the suitability of the simplified version of the LBM method that we applied within the framework of a two-dimensional model for modeling complex cases of contact interaction between liquids and sorbent, when it cannot be carried out by the method of contact wetting. The adsorption properties of shungite with regard to the extraction of various impurities from water-alcohol solutions and the capability of the sorbent to recover were investigated by the method of contact wetting and analyzed by involving the data obtained by the methods of nitrogen adsorption, thermogravimetry and IR spectroscopy. It is shown that the adsorption properties of shungite are due to the presence on its surface of hydroxyl functional groups attached to carbon atoms in phenol or enol form, which give the surface hydrophilic characteristics. These groups play a key role in the adsorption of components from the liquid (aqueous) phase due to the formation of a hydrogen bond during the sorption of components from the liquid phase, and are restored after heating in the temperature range of 80–180 °C with the formation of carbon-containing gases and water. It has been found that silanol groups present in shungite do not participate in sorption. Compared to the original shungite sample, the sample after five cycles of adsorption is characterized by a noticeable effect of mass loss (1.8 %) in the temperature range of 80–180 °С. At the same time, the loss of mass is not significant at temperatures below 100 °С. This suggests that the sorbed substances are in the pores and not on the surface of shungite, and they begin to be removed only after heating above 100 °C. The LBM method was used to study fast-moving processes at the meso-level. A comparative analysis of the experimental data obtained by the method of contact wetting with the results of simulation by the Boltzmann lattice method within the framework of the two-dimensional model was carried out. 2D modeling by the LBM method turned out to be an effective means of studying capillary condensation in mesopores, anticipatory wetting of the solid phase, liquid penetration into a porous medium with different topologies, and the formation of anisotropic droplets and anisotropic bridges. The role of mesopores in the sorption process was analyzed by modeling the behavior of liquid droplets on heterogeneous surfaces and using data on the course of adsorption and capillary processes on the surface of a solid phase with different levels of porosity, roughness, and functional composition.

Effect of Heat Treatment on the Supramolecular Structure of Copolymers Based on Poly(propylene glycol fumarate phthalate) with Acrylic Acid

Previous studies investigating the thermal decomposition of p-PGFPh:AA copolymers in an inert atmosphere have provided only a general understanding of the changes that occur during thermolysis. Comprehensive studies are required to gain a better understanding of these processes [1]. The most comprehensive information on the influence of various factors on both the kinetics and the supramolecular structure of the resulting products can be obtained by combining the method of thermal analysis with IR, mass spectrometry, and scanning electron microscopy. The compounds studied have two different compositions, namely p‑PGFPh:AA 6.77:93.23 mol % and p-PGFPh:AA 86.67:13.33 mol %. These compounds were then subjected to a thermolysis process, which resulted in the emission of gases and a decrease in sample weight. The degradation process can be divided into three stages: 1) Depolymerization of the main chain; 2) Depolymerization of the side chain; 3) Final decomposition. These processes occur sequentially at different temperature ranges. According to TG- and DTG studies, complete decomposition of p-PGFPh:AA copolymers occurred at Tterm = 340–350 °C. In this temperature range, a slight loss of sample mass (less than 10 wt %) was observed along with a slight gas evolution. The main gaseous products from the transformation of the studied samples were CO and CO2. This was supported by IR-CO (2000–2200 cm−1) and CO2 (2310–2370 cm−1) as well as mass spectrometric observations. The final products resulting from the thermolysis of p-PGFPh:AA copolymers were examined under an electron microscope. The results showed a similar morphological pattern of mesostructures with sizes ranging from 0.3–1.5 μm, which were observed depending on the porous structure of the initial polymer material. Based on the experimental data, it can be concluded that the p-PGFPh:AA copolymers (in proportions of 6.77:93.23 mol % and 86.67:13.33 mol %) have a relatively high degree of resistance to heating and do not undergo any changes in chemical composition, particle size and shape. In conclusion, the results clearly indicate that the selection of conditions for pyrolysis plays a crucial role in increasing the thermal stability of polymeric materials. This method allows for purposeful changes in the structure and properties of polymers.

Low Energy (< 10 eV) Electron Collision with Benzonitrile-CCl4 Admixture: A Combined Theoretical and Experimental Study.

Benzonitrile (BZN) and carbon tetrachloride (CCl4) are versatile solvents used as a precursor for the synthesis of many products. As multi-usage molecules, these compounds may be involved in sustainable chemistry processes such as the cold plasma techniques for which the generated electrons are known to be responsible for reactions. Therefore, it is desirable to explore the interaction of low energy electrons with the co-compounds in the gas phase. The production of chlorine and cyanine anions, initiated by the electron collision with CCl4 and BZN, respectively, undergo nucleophilic substitution SN2 reaction with the precursors molecules for the synthesis of chlorobenzene and tricholoacetonitrile. The mechanism of fragmentation of benzonitrile and the synthesis reactions are rationalized by DFT calculations. The yield of the cyanine anion produced from the ion reaction increases with the temperature of the admixture gas, probed in the 25 °C-100 °C temperature range. The present work may contribute to a potential process for the production of chlorobenzene for instance via (cold) plasma techniques.

Photo-triggered Phase Transition of Crystals and Photoactuation.

Photo-triggered phase transition is a new type of phase transition in which a photochromic crystal with a thermal phase transition transforms into an identical high-temperature phase in a temperature region lower than the thermal phase transition temperature upon light irradiation. Here, we report a second crystal that exhibits a photo-triggered phase transition, thereby demonstrating that the photo-triggered phase transition is a general phenomenon that occurs in crystals. When the chiral salicylidenephenylethylamine crystal was irradiated with ultraviolet (UV) light, the photo-triggered phase transition occurred in the temperature range -30 to -10 °C. The photo-triggered phase transition is induced by local stress due to trans-keto molecules produced by photoisomerization near the irradiated surface. Crystal cantilevers exhibited stepwise bending by the combination of the photo-triggered phase transition and photoisomerization. Alternate irradiation with UV and visible light achieved locomotion of single crystals driven by repeated stepwise bending. Finally, a detailed comparison of photo-triggered and non-photo-triggered phase transition crystals revealed that a sufficient molecular conformation change in affordable crystal voids, smooth photoisomerization, and most likely a chiral molecular arrangement are required for inducing the photo-triggered phase transition.

Investigation of the temperature dependence of the dielectric relaxation of chlorobenzene, bromobenzene and iodobenzene

This paper deals with the investigation results of temperature dependence of complex permittivity’sε∗ = έ − iε˝ of chloro, bromo and iodo- benzene at wavelength 11,50 cm and 12,80 cm within the temperature range 20 ÷ -80˚. It is established that dielectric properties of given liquids are characteristic of one relaxation time. The dielectric spectra were studied taking into account other frequencies given in the literature. In all investigated liquids, a jump appears in the real and imaginary parts of the complex permittivity at the point of the phase transition. The temperature dependence of the dielectric relaxation time of molecules in the liquid state has been determined. It was found that with an increase in the amount of the halogen substituent, an increase in the relaxation time occurs. Macroscopic and molecular relaxation times were calculated from the experimental values. The thermodynamic quantities characterizing the process of dielectric relaxation are calculated. The activation enthalpy of dielectric relaxation processes is compared. The studies were carried out using the dielectric spectroscopy method. This method allows a more detailed study of the dielectric properties of the objects of study due to the large equilibrium (“static”) dielectric constant of the object. It has been determined that the height of the potential barrier separating the two equilibrium positions of a polar molecule is greatest in the state of a pure polar liquid and decreases with dilution in a non-polar solvent.

Characterization of elastic wave propagation in high-speed railway tracks considering temperature effects

This study establishes a three-dimensional infinite-length periodic ballasted track model, considering the effect of coupling between bending and torsion and the impact of sleeper width. The GPWE method is employed to investigate the energy bandgap structure of the track. The results show three vertical bending wave bandgaps below 1500 Hz: 0–109 Hz, 110–167 Hz, and 1081–1126 Hz. The node responses from a hammer impact experiment are used in the WSM to calculate the frequency dispersion curves, which confirms the validity of this model. The model is then utilized to analyze the influence of rail temperature forces and temperature-dependent fastener stiffness on the vibration transmission characteristics of the track within a temperature range of −35°C to 25°C. As temperature increases, the starting and cutoff frequency values and the width of bandgaps both decrease nonlinearly and later stabilize, with the width of the Bragg bandgap showing a significant reduction of 83%. The vibration attenuation rate in the bandgap gradually increases and finally stabilizes, especially above 15°C, while the vibration transfer characteristics are not significantly affected by temperature.

Drying kinetics, thermodynamic properties and physicochemical characteristics of Rue leaves

Generally, medicinal plants are harvested with high amount of water, so it is essential to subject the product to drying as soon as possible to prevent degradation before application. Most compounds from medicinal plants are sensitive to drying processes, so it is important to adjust the drying conditions. The objective of this study was to describe the drying of Rue (Ruta chalepensis L.) leaves, select the models that best fit each drying condition, determine the activation energy and thermodynamic properties of the leaves, and evaluate their quality after drying. Leaves were harvested with moisture content of 3.55 ± 0.05 kg water kg−1dry matter and subjected to drying at temperatures of 40, 50, 60 and 70 °C. Valcam model showed the best fit to represent the drying kinetics of Rue leaves at temperatures of 40 and 70 °C, and Midilli model proved to be better for the temperatures of 50 and 60 °C. Effective diffusion coefficient increased linearly with the increase in drying air temperature, and the activation energy was 60.58 kJ mol−1. Enthalpy, entropy and Gibbs free energy values ranged from 57.973 to 57.723 kJ mol−1, from − 0.28538 to − 0.28614 kJ mol−1 K−1 and from 147.34 to 155.91 kJ mol−1, respectively, for the temperature range of 40–70 °C. Drying air temperature promoted darkening or tendency to loss of green color; increase in drying air temperature leads to greater discoloration, as well as a higher concentration of total phenolic compounds (about 221.10 mg GAE mL−1 g–1 dm), with a peak at temperature of 60 °C.

Mechanistic and kinetic insights of the formation of allene and propyne from the C3H3 reaction with water.

Allene (H2C = C = CH2) and propyne (CH3-C≡CH) are important compounds in the combustion chemistry. They can be created from the reaction of proparyl radicals with water. In this study, therefore, a computational study into the C3H3 + H2O potential energy landscape has been carefully conducted. The computed results indicate that the reaction paths forming the products (allene: CH2CCH2 + •OH) and (propyne: HCCCH3 + •OH) prevail under the 300-2000K temperature range, where the latter is much more predominant compared to the former. However, these two products are not easily formed under ambient conditions due to the high energy barriers. In the 300 - 2000K temperature range, the branching ratio for the propyne + •OH product declines from 100 to 86%, whereas the allene + •OH product shows an increase, reaching 14% at 2000K. The overall bimolecular rate constant of the title reaction can be presented by the modified Arrhenius expression of ktotal = 1.94 × 10-12 T0.14 exp[(-30.55kcal.mol-1)/RT] cm3 molecule-1s-1. The total rate constant at the ambient conditions in this work, 2.37 × 10-34 cm3 molecule-1s-1, was found to be over five orders of magnitude lower than the total rate constant of the C3H3 + NH3 reaction, 7.98 × 10-29 cm3 molecule-1s-1, calculated by Hue et al. (Int. J. Chem. Kinet. 2020, 4(2), 84-91). The results in this study contribute to elucidating the mechanism of allene and propylene formation from the C3H3 + H2O reaction, and they can be used for modeling C3H3-related systems under atmospheric and combustion conditions. All the geometric structures of the C3H3 + H2O system were optimized by the B3LYP method in conjunction with the 6-311 + + G(3df,2p) basis set. Single-point energies of these species were calculated at the CCSD(T)/6-311 + + G(3df,2p) level of theory. The CCSD(T)/CBS level has also been used to compute single-point energies for the two major reaction channels (C3H3 + H2O → allene + •OH and C3H3 + H2O → propyne + •OH). Rate constants and branching ratios of the key reaction channels were calculated in the 300-2000K temperature interval using the Chemrate software based on the transition state theory (TST) with Eckart tunneling corrections.

X-ray Thomson scattering absolute intensity from the f-sum rule in the imaginary-time domain

We present a formally exact and simulation-free approach for the normalization of X-ray Thomson scattering (XRTS) spectra based on the f-sum rule of the imaginary-time correlation function (ITCF). Our method works for any degree of collectivity, over a broad range of temperatures, and is applicable even in nonequilibrium situations. In addition to giving us model-free access to electronic correlations, this new approach opens up the intriguing possibility to extract a plethora of physical properties from the ITCF based on XRTS experiments.

Modeling the species occurrence probability and response of climate change on Himalayan Somalata plant under different Shared Socioeconomic Pathways.

In this study, the current distribution probability of Ephedra gerardiana (Somalata), a medicinally potent species of the Himalayas, was assessed, and its spatial distribution change was forecasted until the year 2100 under three Shared Socioeconomic Pathways. Here, we used the maximum entropy model (MaxEnt) on 274 spatially filtered occurrence data points accessed from GBIF and other publications, and 19 bioclimatic variables were used as predictors against the probability assessment. The area under the curve, Continuous Boyce Index, True Skill Statistics, and kappa values were used to evaluate and validate the model. It was observed that the SSP5-8.5, a fossil fuel-fed scenario, saw a maximum habitat decline for E. gerardiana driving its niche towards higher altitudes. Nepal Himalayas witnessed a maximum decline in suitable habitat for the species, whereas it gained area in Bhutan. In India, regions of Himachal Pradesh, Uttarakhand, Jammu and Kashmir, and Sikkim saw a maximum negative response to climate change by the year 2100. Mean annual temperature, isothermality, diurnal temperature range, and precipitation seasonality are the most influential variables isolated by the model that contribute in defining the species' habitat. The results provide evidence of the effects of climate change on the distribution of endemic species in the study area under different scenarios of emissions and anthropogenic coupling. Certainly, the area of consideration encompasses several protected areas, which will become more vulnerable to increased variability of climate, and regulating their boundaries might become a necessary step to conserve the regions' biodiversity in the future.

Protic ionic Liquids-Water Interactions: A study on 2-Hydroxypropylammonium formate through experimental analysis and computer simulations

In this study, interactions within a mixture of the protic ionic liquid 2-hydroxypropylammonium formate and water were investigated across the entire range of ionic liquid compositions and a wide temperature range from 283.15 K to 333.15 K. This investigation was based on the measurement results of density, viscosity, and electrical conductivity, and was supported by computational simulations. The synthesized ionic liquid was further characterized thermally using Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC) techniques. The study focuses on the analysis of excess molar quantities of volume, thermal expansion coefficients, viscosity, and Gibbs energy of viscous flow, aiming to examine the influence of temperature and mixture composition on thermophysical properties. The impact of temperature on the system’s viscosity and Angell’s strength parameter was investigated to assess the influence of the ionic liquid’s content on the system’s structural organization. The dependency of molar conductivity on viscosity was analyzed through the Walden rule. Based on this analysis, the effect of temperature and mixture composition on deviations from the ideal behavior in diluted solutions of strong electrolytes was estimated. Computational molecular dynamics simulations were employed for a more detailed study of the structural organization of the system’s components.

Deformation behavior, constitutive modeling and microstructure evolution of 2195 Al-Li alloy deformed at high strain rates and cryogenic temperatures

High-speed and cryogenic-temperature forming technologies have exhibited great potential for fabricating advanced Al-Li alloy components for aircraft due to their ability to enhance materials’ formability. However, there remains an urgent need to study the high-accuracy constitutive model and complex deformation mechanism of Al-Li alloys deformed at high strain rates and cryogenic temperatures. In this study, the flow stress behavior and microstructure evolution of 2195 Al-Li alloy were investigated over a wide stain rate range (from 2000 s−1 to 5000 s−1) and temperature range (from 298 K to 123 K). The flow stress increases by ∼ 32% at 2000 s−1 and ∼ 37% at 5000 s−1 as the deformation temperature drops from 298 K to 123 K, but only increases by ∼ 4% at 298 K and ∼ 8% at 123 K as the strain rate increases from 2000 s−1 to 5000 s−1. At the high strain rate of 5000 s−1, the T1 phases exhibit bending (at 298 K) and fracturing (at 123 K), with increased lattice distortion and substructure generation around the intersections of T1 phases. A new constitutive model (g-Johnson-Cook model) is developed, which shows a higher accuracy than both the Arrhenius model and Johnson-Cook model in describing the deformation behavior.

Record of a pioneering geothermal borehole in London

This paper records the results of a pioneering exploration borehole drilled in 1984 to a depth of 403.84 m in the London Basin and underlying London–Brabant basement high. The key objectives of the project were to measure the equilibrium temperature in the Paleozoic basement, estimate the temperature gradient after climate impact corrections and assess the heat flow in the area. From this, estimates of temperature at depths of 2000 m could be made with a view to evaluating potential geothermal resources. From the downhole measurements, a temperature gradient of 16°C km −1 was estimated with a temperature range between 46°C and 51°C at a depth of 2000 m, considered to be consistent with other UK sites where there is no contribution from high heat production granites. The results of the Thamesmead exploration borehole suggested that the geothermal potential of the Devonian and the Paleozoic basement below London is poor, and no further work was carried out. The work has remained unpublished until now but in view of the current renewed interest in geothermal resources it is appropriate to make the work public. Although the results were not encouraging, they do remain as a contribution to the revitalized assessment of geothermal resources in the London area and the UK in general.

The effect of the outer-sphere cations on the photophysical and magnetic properties of rare earth complexes with 2,2,2-trichloro-N-(diphenylphosphoryl)acetamide

Two series of rare earth coordination compounds have been synthesized (Na[RE(L4)] (labeled as 1RE) and PPh4[RE(L4)] (labeled as 2RE), where RE = Y3+, Eu3+, Tb3+, L = 2,2,2-trichloro-N-(diphenylphosphoryl)acetamide) to determine the possibility of modifying their photophysical and magnetical properties by changing the counterion. The crystal structure of 1RE was determined based on the single-crystal X-ray diffraction and the crystal structure of 2RE was determined based on quantum chemistry computational procedures. Characterization of the physicochemical properties of the compounds was carried out using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), 1H and 31P NMR spectroscopy as well as FT-IR, absorption and luminescence spectroscopy in the temperature range of 300 - 77 K. The rate constants of radiative (Arad) and non-radiative (Anrad) transitions, intrinsic (QLnLn) and overall (QLnL) emission quantum yields, sensitization efficiency (ηsens), the experimental and theoretical intensity parameters (Ωλ), the forward (WS, WT) and backward (WbS, WbT) intramolecular energy transfer (IET) rates were determined. Magnetic properties of Tb3+ compounds were studied in a constant field of 0.5 T in the temperature range of 1.8–300 K. Dynamic AC magnetic susceptibility measurements were carried out as a function of temperature and frequency for 1Tb and 2Tb. Only in the case of 2Tb, in the presence of an external DC field, a slight temperature dependence of in-phase χ′ and out-of-phase χ'' susceptibility was recorded. Based on experimental and theoretical results, the significant effect of counterion on the photophysical and magnetic properties of RE chelates has been demonstrated and clarified, providing valuable guidance for the design of bifunctional electromagnetic radiation converters.

MOF-derived high oxygen vacancies CuO/CeO2 catalysts for low-temperature CO preferential oxidation

The CO preferential oxidation reaction (CO-PROX) is an effective strategy to remove residual poisonous CO in proton exchange membrane fuel cells, in which oxygen vacancies play a critical role in CO adsorption and activation. Herein, a series of CuO/CeO2 catalysts derived from Ce-MOFs precursors were synthesized using different organic ligands via the hydrothermal method and the CO-PROX performance was investigated. The CuO/CeO2-135 catalyst derived from homophthalic tricarboxylic acid (1,3,5-H3BTC) exhibited superior catalytic performance with 100 % CO conversion at a relatively low temperature (T100% = 100 °C), with a wide reaction temperature range and excellent stability. The superior catalytic properties were attributed to the structural improvements provided by the 1,3,5-H3BTC precursors and the promotional effects of oxygen vacancies. Additionally, in-situ Raman spectroscopy was performed to verify the dynamic roles of oxygen vacancies for CO adsorption and activation, while in-situ DRIFTS analysis revealed key intermediates in the CO-PROX reaction, shedding light on the mechanistic aspects of the catalytic process. This work not only demonstrates insights into the effective CuO/CeO2 catalysts for CO preferential oxidation, but also provides a feasible way to synthesize MOF-derived catalysts.

Method for determining the Schottky injection barrier at the interface of a metal electrode with insulating oil or pressboard

The Schottky injection barrier plays a crucial role in determining the charge movement and migration process, yet its electric field and temperature properties remain unclear. The precise determination of the Schottky injection barrier value is essential for understanding the charge migration dynamics at the interface between the metal electrode and the oil-pressboard insulating medium. This study introduces a computational approach to determine the Schottky injection barrier, derived from classical Schottky emission theory. The methodology employed in this research aligns with previous studies, utilizing the Schottky emission current mechanism to describe steady-state conduction current. Results indicate that the Schottky injection barrier increases with temperature, with a 17.09% rise for oil-electrode and an 8.3% increase for pressboard-electrode in the temperature range of 299 K–353 K. These temperature-dependent variations are attributed to the negative temperature dependence of the Fermi energy levels of the metal electrodes. Furthermore, the impact of electric field strength on the Schottky injection barrier is found to be minimal. By developing a bipolar charge transport simulation model and validating the injection barrier for 0.5 mm oil-immersed pressboard, this study confirms the accuracy of the calculated Schottky injection barrier. The insights provided in this research could aid in simulating charge transport and analyzing charge characteristics in oil-paper/pressboard insulation systems.

Autocombustion Route Derived Zinc Ferrite Nanoparticles as Chemiresistive Sensor for Detection of Alcohol Vapors.

Prolonged exposure to alcohol vapors can have detrimental effects on human health, potentially leading to eye irritation, dizziness, and in some cases, damage to the nervous system. The present article aims to provide a comprehensive understanding on the synthesis and characterization of zinc ferrite (ZnFe2O4) nanoparticles, as well as their interactions with a range of alcohol vapors, including methanol, ethanol, n-propanol, and isopropanol. These alcohols differ in their molecular weight, boiling points, diffusivity, and other properties. The study reveals the semiconducting ZnFe2O4 nanoparticulate sensor's capability for reversible, repeatable, and sensitive detection of alcohol vapors. The sensor exhibits the highest response to ethanol within operating temperature range (225-300 °C). An attempt is made to establish a correlation between the properties of the target analytes and the observed sensing signals. Additionally, the response conductance transients of ZnFe2O4 under the exposure to the studied alcohol vapors are modeled based on the Langmuir-Hinshelwood adsorption mechanism. The characteristic time constants obtained from this modeling are justified with respect to the properties of the analytes.