147,464 results on '"TEMPERATURE effect"'
Search Results
2. Origin of the vibrational structure of the first absorption band of cis/trans isomeric 1,6-diphenylhexatrienes by (TD)DFT calculations.
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Martin-Somer, Ana and Catalán, Javier
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DENSITY functional theory , *DOUBLE bonds , *ABSORPTION spectra , *TEMPERATURE effect , *FUNCTIONALS - Abstract
We present a detailed spectroscopic analysis of the first absorption band of the six possible conformers of 1,6-diphenyl-1,3,5-hexatriene, obtained by changing the configuration of trans double bonds to cis. To this end, we computed the absorption spectra using FCclasses 3.0 code. First, we assessed the performance of PBE0 and CAM-B3LYP density functional theory functionals with different basis sets to reproduce the experimental spectra. Additionally, we considered different models to compute the spectra. PBE0/def2tZVP with an adiabatic hessian model with internal coordinates yields results in very good agreement with experimental data. Subsequently, we analyzed the different contributions of vibronic transition to the spectral structure, correlating ground state conformation with spectral shape, and studied the effect of temperature on the absorption first band. [ABSTRACT FROM AUTHOR]
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- 2024
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3. Measurement bias in self-heating x-ray free electron laser experiments from diffraction studies of phase transformation in titanium.
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Ball, O. B., Husband, R. J., McHardy, J. D., McMahon, M. I., Strohm, C., Konôpková, Z., Appel, K., Cerantola, V., Coleman, A. L., Cynn, H., Dwivedi, A., Goncharov, A. F., Graafsma, H., Huston, L. Q., Hwang, H., Kaa, J., Kim, J.-Y., Koemets, E., Laurus, T., and Li, X.
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TEMPERATURE distribution , *FINITE element method , *PHASE transitions , *TEMPERATURE effect , *X-ray diffraction , *FREE electron lasers - Abstract
X-ray self-heating is a common by-product of X-ray Free Electron Laser (XFEL) techniques that can affect targets, optics, and other irradiated materials. Diagnosis of heating and induced changes in samples may be performed using the x-ray beam itself as a probe. However, the relationship between conditions created by and inferred from x-ray irradiation is unclear and may be highly dependent on the material system under consideration. Here, we report on a simple case study of a titanium foil irradiated, heated, and probed by a MHz XFEL pulse train at 18.1 keV delivered by the European XFEL using measured x-ray diffraction to determine temperature and finite element analysis to interpret the experimental data. We find a complex relationship between apparent temperatures and sample temperature distributions that must be accounted for to adequately interpret the data, including beam averaging effects, multivalued temperatures due to sample phase transitions, and jumps and gaps in the observable temperature near phase transformations. The results have implications for studies employing x-ray probing of systems with large temperature gradients, particularly where these gradients are produced by the beam itself. Finally, this study shows the potential complexity of studying nonlinear sample behavior, such as phase transformations, where biasing effects of temperature gradients can become paramount, precluding clear observation of true transformation conditions. [ABSTRACT FROM AUTHOR]
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- 2024
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4. First-principles investigations of the energetics of He-defect cluster in FCC nickel.
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Huang, Gui-Yang, Zhou, Yanyao, Li, Yongchun, and Hu, Xunxiang
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LATTICE dynamics , *BINDING energy , *ACTIVATION energy , *TEMPERATURE effect , *HELIUM - Abstract
We have done comprehensive first-principles calculations of He-vacancy-interstitial clusters in FCC nickel. The calculated total binding energy of V n (Ni vacancy cluster), I n (Ni interstitial cluster), He n (helium interstitial cluster), He n V (helium interstitials in one vacancy), and He n V 2 (helium interstitials in one divacancy) cluster is reported. The total binding energy of a two Ni interstitial cluster is relatively large (1.07 eV), and the binding energy between a monovacancy and a vacancy cluster containing < 20 vacancies is relatively small (< 0.8 eV). The dissociation/emission energy barrier of a Ni interstitial from a He 3 interstitial cluster (three helium interstitial clusters) and a He 8 V cluster (eight helium interstitials in one vacancy) is ≤ 1.06 and ≤ 1.32 eV, respectively. The diffusion activation energy of helium is 1.36 eV via a dissociative mechanism. Comparisons with reported experimental results of helium diffusion and helium desorption have been done to verify the calculation results. The relative stability of stacking fault tetrahedron and void has been investigated further based on quasi-harmonic phonon calculations directly to consider the temperature effects. The reported binding energy results can be used to build molecular simulation potentials or provide input parameters for the cluster dynamics or lattice Monte Carlo simulations of helium-defect cluster evolution. [ABSTRACT FROM AUTHOR]
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- 2024
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5. Simulating temperature and tautomeric effects for vibrationally resolved XPS of biomolecules: Combining time-dependent and time-independent approaches to fingerprint carbonyl groups.
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Wei, Minrui, Zuo, Junxiang, Tian, Guangjun, and Hua, Weijie
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X-ray photoelectron spectroscopy , *CARBONYL group , *TEMPERATURE effect , *CHEMICAL bond lengths , *COUPLINGS (Gearing) - Abstract
Carbonyl groups (C=O) play crucial roles in the photophysics and photochemistry of biological systems. O1s x-ray photoelectron spectroscopy allows for targeted investigation of the C=O group, and the coupling between C=O vibration and O1s ionization is reflected in the fine structures. To elucidate its characteristic vibronic features, systematic Franck–Condon simulations were conducted for six common biomolecules, including three purines (xanthine, caffeine, and hypoxanthine) and three pyrimidines (thymine, 5F-uracil, and uracil). The complexity of simulation for these biomolecules lies in accounting for temperature effects and potential tautomeric variations. We combined the time-dependent and time-independent methods to efficiently account for the temperature effects and to provide explicit assignments, respectively. For hypoxanthine, the tautomeric effect was considered by incorporating the Boltzmann population ratios of two tautomers. The simulations demonstrated good agreement with experimental spectra, enabling differentiation of two types of carbonyl oxygens with subtle local structural differences, positioned between two nitrogens (O1) or between one carbon and one nitrogen (O2). The analysis provided insights into the coupling between C=O vibration and O1s ionization, consistently showing an elongation of the C=O bond length (by 0.08–0.09 Å) upon O1s ionization. [ABSTRACT FROM AUTHOR]
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- 2024
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6. Dislocation evolution and hardening of CoCrFeMnNi high entropy alloy under Fe ion irradiation at room temperature and 500 °C.
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Zhang, Lisong, Zhang, Peng, Li, Na, Zhang, Xiaonan, and Mei, Xianxiu
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HIGH-entropy alloys , *NUCLEAR reactor materials , *DISLOCATION density , *HIGH temperatures , *BINDING energy , *TEMPERATURE effect - Abstract
Recently, high entropy alloy (HEA) has become a research hotspot as a new candidate structural material in nuclear reactors due to its good irradiation resistance in swelling and hardening. Focusing on the temperature effect of irradiation damage, this work investigated the influence of irradiation temperature on dislocation evolution and irradiation hardening of HEAs. CoCrFeMnNi HEA was irradiated by high-energy Fe ions at room temperature and 500 °C. It was found that dense small dislocations were produced in the damage attenuation region (i.e., the tail of the ion range) of HEAs after irradiation at room temperature, whereas the irradiation-induced dislocations could not be observed in the damage attenuation region when the irradiation temperature was increased to 500 °C. For the small-sized dislocations, dissociation may occur more easily than long-range migration in HEAs (such as CoCrFeNi systems) due to the inhibition of defect migration and the decrease in defect binding energy, and this order is reversed in pure metals (such as Ni, W). Therefore, at 500 °C irradiation, small dislocations in the damage attenuation region of CoCrFeMnNi HEAs were dissociated before migrating to deeper regions, thereby resulting in the depth of dislocation distribution smaller than the stopping and range of ions in matter-calculated damage stopping depth, unlike the phenomenon in pure metals where dislocations migrated to regions exceeding the calculated depth. In addition, the dislocation density of CoCrFeMnNi HEAs decreased significantly due to the promotion of dissociation and merging of dislocations by elevated temperatures, and the hardening after 500 °C irradiation was less than that after room temperature irradiation. [ABSTRACT FROM AUTHOR]
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- 2024
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7. Optimal tree tensor network operators for tensor network simulations: Applications to open quantum systems.
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Li, Weitang, Ren, Jiajun, Yang, Hengrui, Wang, Haobin, and Shuai, Zhigang
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QUANTUM operators , *SPECTRAL energy distribution , *TEMPERATURE effect , *PHONONS , *TOPOLOGY - Abstract
Tree tensor network states (TTNS) decompose the system wavefunction to the product of low-rank tensors based on the tree topology, serving as the foundation of the multi-layer multi-configuration time-dependent Hartree method. In this work, we present an algorithm that automatically constructs the optimal and exact tree tensor network operators (TTNO) for any sum-of-product symbolic quantum operator. The construction is based on the minimum vertex cover of a bipartite graph. With the optimal TTNO, we simulate open quantum systems, such as spin relaxation dynamics in the spin-boson model and charge transport in molecular junctions. In these simulations, the environment is treated as discrete modes and its wavefunction is evolved on equal footing with the system. We employ the Cole–Davidson spectral density to model the glassy phonon environment and incorporate temperature effects via thermo-field dynamics. Our results show that the computational cost scales linearly with the number of discretized modes, demonstrating the efficiency of our approach. [ABSTRACT FROM AUTHOR]
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- 2024
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8. Modeling temperature-dependent transport properties in dissipative particle dynamics: A top-down coarse-graining toward realistic dynamics at the mesoscale.
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Lauriello, N., Lísal, M., Boccardo, G., Marchisio, D., and Buffo, A.
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PARTICLE dynamics , *MESOSCOPIC systems , *TEMPERATURE effect , *WATER use - Abstract
Dissipative particle dynamics (DPD) is a widespread computational tool to simulate the behavior of soft matter and liquids in and out of equilibrium. Although there are many applications in which the effect of temperature is relevant, most of the DPD studies have been carried out at a fixed system temperature. Therefore, this work investigates how to incorporate the effect of system temperature variation within the DPD model to capture realistic temperature-dependent system properties. In particular, this work focuses on the relationship between temperature and transport properties, and therefore, an extended DPD model for transport properties prediction is employed. Transport properties, unlike the equilibrium properties, are often overlooked despite their significant influence on the flow dynamics of non-isothermal mesoscopic systems. Moreover, before simulating the response of the system induced by a temperature change, it is important to first estimate transport properties at a certain temperature. Thus here, the same fluid is simulated across different temperature conditions using isothermal DPD with the aim to identify a temperature-dependent parametrization methodology, capable of ensuring the correctness of both equilibrium and dynamical properties. Liquid water is used as a model system for these analyses. This work proposes a temperature-dependent form of the extended DPD model where both conservative and non-conservative interaction parameters incorporate the variation of the temperature. The predictions provided by our simulations are in excellent agreement with experimental data. [ABSTRACT FROM AUTHOR]
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- 2024
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9. Effect of the deformation temperature and strain on the strain rate sensitivity of fcc medium-entropy alloys.
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Mahato, Swati, Jha, Saumya R., Sonkusare, Reshma, Biswas, Krishanu, and Gurao, Nilesh P.
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STRAINS & stresses (Mechanics) , *FACE centered cubic structure , *SHEAR (Mechanics) , *TEMPERATURE effect , *DISLOCATION structure , *STRAIN rate , *GRAIN size - Abstract
The primary objective of the present investigation is to elucidate the operative micromechanisms influencing the strain rate sensitivity and activation volume in (FeCrNi)99Si1 and FeMnNi medium-entropy alloys. Room-temperature nanoindentation experiments at different loading rates were performed to study the evolution of the strain rate sensitivity and activation volume in (FeCrNi)99Si1 and FeMnNi medium-entropy alloys. The (FeCrNi)99Si1 samples were subjected to plane strain deformation by rolling at 77 and 300 K to study the effect of temperature on the strain rate sensitivity, while the FeMnNi and (FeCrNi)99Si1 samples were subjected to simple shear deformation by high-pressure torsion at 300 K to examine the effect of strains. Contrary to the well-documented trend observed in fcc metals and alloys, where the strain rate sensitivity typically increases with decreasing grain size, the present study reveals a distinct behavior for the current alloys. Similarly, these alloys are characterized by extremely low activation volumes of a few tens of b3 compared to 100–1000 b3 for conventional fcc metals and alloys in the microcrystalline grain size regime. Unlike conventional fcc metals and alloys, there is an insignificant change in the activation volume of the current high-/medium-entropy alloy (H/MEA) with decreasing grain size from the microcrystalline to nanocrystalline regime. The unique evolution of strain rate sensitivity and activation volume in H/MEAs is explained in terms of the evolution of distinct dislocation structures as well as synergistic operation of additional mechanisms such as twinning, phase transformation from fcc to hcp phases, cluster strengthening, and short-range ordering due to the aperiodic energy landscape existing in MEAs. [ABSTRACT FROM AUTHOR]
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- 2024
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10. Effects of temperature and CO2 concentration on the early stage nucleation of calcium carbonate by reactive molecular dynamics simulations.
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Qin, Ling, Yang, Junyi, Bao, Jiuwen, Sant, Gaurav, Wang, Sheng, Zhang, Peng, Gao, Xiaojian, Wang, Hui, Yu, Qi, Niu, Ditao, and Bauchy, Mathieu
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MOLECULAR dynamics , *CALCIUM carbonate , *CARBON sequestration , *TEMPERATURE effect , *NUCLEATION , *ACTIVATION energy - Abstract
It is significant to investigate the calcium carbonate (CaCO3) precipitation mechanism during the carbon capture process; nevertheless, CaCO3 precipitation is not clearly understood yet. Understanding the carbonation mechanism at the atomic level can contribute to the mineralization capture and utilization of carbon dioxide, as well as the development of new cementitious materials with high-performance. There are many factors, such as temperature and CO2 concentration, that can influence the carbonation reaction. In order to achieve better carbonation efficiency, the reaction conditions of carbonation should be fully verified. Therefore, based on molecular dynamics simulations, this paper investigates the atomic-scale mechanism of carbonation. We investigate the effect of carbonation factors, including temperature and concentration, on the kinetics of carbonation (polymerization rate and activation energy), the early nucleation of calcium carbonate, etc. Then, we analyze the local stresses of atoms to reveal the driving force of early stage carbonate nucleation and the reasons for the evolution of polymerization rate and activation energy. Results show that the higher the calcium concentration or temperature, the higher the polymerization rate of calcium carbonate. In addition, the activation energies of the carbonation reaction increase with the decrease in calcium concentrations. [ABSTRACT FROM AUTHOR]
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- 2024
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11. Effect of temperature on polaronic transport in CeO2 thin-film.
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Paul, Mousri, Karmakar, Sabyasachi, Tripathi, Shilpa, Jha, S. N., Satpati, Biswarup, and Chakraborty, Supratic
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CERIUM oxides , *TEMPERATURE effect , *ELECTRONIC band structure , *PHOTOELECTRON spectroscopy , *POLARONS , *SUBSTRATES (Materials science) - Abstract
The outstanding catalytic property of cerium oxide (CeO2) strongly depends on the polaron formation due to the oxygen vacancy ( V ̈ O ) defect and Ce4+ to Ce3+ transformation. Temperature plays an important role in the case of polaron generation in CeO2 and highly influences its electrical transport properties. Therefore, a much needed attention is required for detailed understanding of the effect of temperature on polaron formation and oxygen vacancy migration to get an idea about the improvement in the redox property of ceria. In this work, we have probed the generation of polarons in CeO2 thin-film deposited on a silicon (Si) substrate using the resonance photoemission spectroscopy (RPES) study. The RPES data show an increase in polaron density at the substrate–film interface of the thermally annealed film, indicating the formation of an interfacial Ce2O3 layer, which is, indeed, a phase change from the cubic to hexagonal structure. This leads to a modified electronic band structure, which has an impact on the capacitance–voltage (C–V) characteristics. This result nicely correlates the microscopic property of polarons and the macroscopic transport property of ceria. [ABSTRACT FROM AUTHOR]
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- 2024
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12. Theoretical investigation of (La4O6)n, (La2Ce2O7)n, and (Ce4O8)n nanoclusters (n = 10, 18): Temperature effects and O-vacancy formation.
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Mocelim, Mauricio, Santos, Mylena N., Bittencourt, Albert F. B., Lourenço, Tuanan C., and Da Silva, Juarez L. F.
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TEMPERATURE effect , *PHASE transitions , *RADIAL distribution function , *CERIUM oxides , *TRANSITION temperature , *DENSITY functional theory - Abstract
We report a theoretical investigation of temperature, size, and composition effects on the structural, energetic, and electronic properties of the (La4O6)n, (La2Ce2O7)n, and (Ce4O8)n nanoclusters (NCs) for n = 10, 18. Furthermore, we investigated the single O vacancy formation energy as a function of the geometric location within the NC. Our calculations are based on the combination of force-field molecular dynamics (MD) simulations and density functional theory calculations. We identified a phase transition from disordered to ordered structures for all NCs via MD simulations and structural analysis, e.g., radius changes, radial distribution function, common neighbor analysis, etc. The transition is sharp for La36Ce36O126, La20Ce20O70, and Ce72O144 due to the crystalline domains in the core and less abrupt for Ce40O80, La40O60, and La72O108. As expected, radius changes are abrupt at the transition temperature, as are morphological differences between NCs located below and above the transition temperature. We found a strong dependence on the O vacancy formation energy (Evac) and its location within the NCs. For example, for La40O60, Evac decreases almost linearly as the distance from the geometric center increases; however, the same trend was not observed for Ce40O80, while there are large deviations from the linear trend for La20Ce20O70. Evac has smaller values for Ce40O80 and higher values for La40O60, that is, almost three times, while Evac has intermediate values for mixed oxides, as expected from weighted averages. Therefore, the mixture of one formula unit of La2O3 with two formula units of CeO2 has the effect of increasing the stability of CeO2 (binding energy), which increases the magnitude of the formation energy of the O vacancy. [ABSTRACT FROM AUTHOR]
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- 2024
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13. Prediction of the univariant two-phase coexistence line of the tetrahydrofuran hydrate from computer simulation.
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Algaba, Jesús, Romero-Guzmán, Cristóbal, Torrejón, Miguel J., and Blas, Felipe J.
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COMPUTER simulation , *DISPERSIVE interactions , *TETRAHYDROFURAN , *MOLECULAR dynamics , *GAS hydrates , *TEMPERATURE effect - Abstract
In this work, the univariant two-phase coexistence line of the tetrahydrofuran (THF) hydrate is determined from 100 to 1000 bar by molecular dynamics simulations. This study is carried out by putting in contact a THF hydrate phase with a stoichiometric aqueous solution phase. Following the direct coexistence technique, the pressure is fixed, and the coexistence line is determined by analyzing if the hydrate phase grows or melts at different values of temperature. Water is described using the well-known TIP4P/Ice model. We have used two different models of THF based on the transferable parameters for phase equilibria-united atom approach (TraPPE-UA), the original (flexible) TraPPe-UA model and a rigid and planar version of it. Overall, at high pressures, small differences are observed in the results obtained by both models. However, large differences are observed in the computational efforts required by the simulations performed using both models, being the rigid and planar version much faster than the original one. The effect of the unlike dispersive interactions between the water and THF molecules is also analyzed at 250 bar using the rigid and planar THF model. In particular, we modify the Berthelot combining rule via a parameter ξO-THF that controls the unlike water–THF dispersive interactions. We analyze the effect on the dissociation temperature of the hydrate when ξO-THF is modified from 1.0 (original Berthelot combining rule) to 1.4 (modified Berthelot combining rule). We use the optimized value ξO-THF = 1.4 and the rigid THF model in a transferable way to predict the dissociation temperatures at other pressures. We find excellent agreement between computer simulation predictions and experimental data taken from the literature. [ABSTRACT FROM AUTHOR]
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- 2024
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14. Temperature dependence of the dynamics and interfacial width in nanoconfined polymers via atomistic simulations.
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Patsalidis, Nikolaos, Papamokos, George, Floudas, George, and Harmandaris, Vagelis
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INTERFACE dynamics , *TEMPERATURE effect , *MOLECULAR dynamics , *TEMPERATURE , *HIGH temperatures , *INTERFACIAL friction - Abstract
We present a detailed computational study on the temperature effect of the dynamics and the interfacial width of unentangled cis-1,4 polybutadiene linear chains confined between strongly attractive alumina layers via long, several μs, atomistic molecular dynamics simulations for a wide range of temperatures (143–473 K). We examine the spatial gradient of the translational segmental dynamics and of an effective local glass temperature ( T g L ). The latter is found to be much higher than the bulk Tg for the adsorbed layer. It gradually reduces to the bulk Tg at about 2 nm away from the substrate. For distant regions (more than ≈ 1.2 n m), a bulk-like behavior is observed; relaxation times follow a typical Vogel–Fulcher–Tammann dependence for temperatures higher than Tg and an Arrhenius dependence for temperatures below the bulk Tg. On the contrary, the polymer chains at the vicinity of the substrate follow piecewise Arrhenius processes. For temperatures below about the adsorbed layer's T g L , the translational dynamics follows a bulk-like (same activation energy) Arrhenius process. At higher temperatures, there is a low activation energy Arrhenius process, caused by high interfacial friction forces. Finally, we compute the interfacial width, based on both structural and dynamical definitions, as a function of temperature. The absolute value of the interfacial width depends on the actual definition, but, regardless, the qualitative behavior is consistent. The interfacial width peaks around the bulk Tg and contracts for lower and higher temperatures. At bulk Tg, the estimated length of the interfacial width, computed via the various definitions, ranges between 1.0 and 2.7 nm. [ABSTRACT FROM AUTHOR]
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- 2024
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15. Fluorescence pressure sensors: Calibration of ruby, Sm2+: SrB4O7, and Sm3+: YAG to 55 GPa and 850 K.
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Wei, Yingzhan, Zhou, Qiang, Zhang, Caizi, Li, Liang, Li, Xinyang, and Li, Fangfei
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SAMARIUM , *PRESSURE sensors , *ND-YAG lasers , *YTTRIUM aluminum garnet , *TEMPERATURE effect , *FLUORESCENCE , *CALIBRATION - Abstract
In this work, a calibration of ruby, samarium-doped strontium tetraborate (Sm2+: SrB4O7), and samarium-doped yttrium aluminum garnet (Sm3+: YAG) using Raman and fluorescence spectra was conducted within the temperature range of 296–850 K and pressure range of 0–55 GPa. The obtained calibration can be applied independently for high-temperature or high-pressure conditions and described as the unit form of P = (A′/B′) × [(λ/λT)B′ − 1] with A′ = A (296 K) + A1 × (T − 296) + A2 × (T − 296)2, B′ = B(296 K) + B1 × (T – 296), and λT = λT (296 K) + ΔλT, where the specific parameters are provided in the main text. It was observed that for the λ1 line (5D0 → 7F0 transition, about 685.2 nm under ambient conditions, also known as the 0-0 line) of Sm2+: SrB4O7, the neglect of the temperature effect on the pressure coefficient may lead to an underestimation of pressure above 35–40 GPa, with a maximum deviation of approximately 2.5 GPa within the range of 55 GPa and 850 K. For Sm3+: YAG, it may introduce significant errors under the whole high temperature and high pressure range if the effect of temperature is ignored, that is, about 3.9 GPa for Y1 line (4G5/2 → 6H7/2 transition, about 617.8 nm under ambient conditions) and 4.6 GPa for Y2 line (4G5/2 → 6H7/2 transition, about 616.0 nm under ambient conditions) at 850 K. Comparing the three fluorescence pressure sensors, the ruby has the strongest signal intensity and highest temperature sensitivity, and the Sm2+: SrB4O7 and the Sm3+: YAG possess lower temperature sensibility, wider used temperature range, and better spectral quality under high temperature and high pressure (HTHP), especially Sm2+: SrB4O7, which has a sharp high-intensity single peak λ1, perhaps the most promising sensor for high P–T experiments. Therefore, in view of the potential deflections of fluorescence peaks of each pressure sensor under HTHP, we recommend utilizing the HTHP-corrected relationships for pressure calibration. [ABSTRACT FROM AUTHOR]
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- 2024
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16. Room-Temperature Superconductivity Heats Up.
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Greengard, Samuel
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SUPERCONDUCTIVITY , *TEMPERATURE effect , *GRAPHITE , *ELECTRIC power transmission , *ENERGY dissipation - Abstract
The quest for room-temperature superconductivity captivates researchers, as it could revolutionize energy efficiency, computing, and electronics by enabling near-zero energy loss during electrical transmission. However, finding the right materials to achieve this goal has been an elusive challenge, with past breakthroughs often proving irreproducible or flawed. Recently, scientists reported a new method using defects in graphite that may enable superconductivity at ambient temperatures, though skepticism remains until further validation occurs. Achieving reliable room-temperature superconductivity could drastically transform technology, from power grids to quantum computing.
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- 2024
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17. High-temperature effects for transition state calculations in solids.
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Ke, Chengxuan, Nie, Chenxi, and Luo, Guangfu
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ELECTRONIC excitation , *KIRKENDALL effect , *TEMPERATURE effect , *HIGH temperatures , *ACTIVATION energy , *SEMICONDUCTOR defects - Abstract
Transition state calculation is a critical technique to understand and predict versatile dynamical phenomena in solids. However, the transition state results obtained at 0 K are often utilized for the prediction or interpretation of dynamical processes at high temperatures, and the error bars of such an approximation are largely unknown. In this benchmark study, all the major temperature effects, including lattice expansion, lattice vibration, electron excitation, and band-edge shift, are evaluated with first-principles calculations for defect diffusion in solids. With the inclusion of these temperature effects, the notable discrepancies between theoretical predictions at 0 K and the experimental diffusivities at high temperatures are dramatically reduced. In particular, we find that lattice expansion and lattice vibration are the dominant factors lowering the defect formation energies and hopping barriers at high temperatures, but the electron excitation exhibits minor effects. In sharp contrast to typical assumptions, the attempt frequency with lattice expansion and vibration varies significantly with materials: several THz for aluminum bulk but surprisingly over 500 THz for 4H-SiC. For defects in semiconductors, the band-edge shift is also significant at high temperatures and plays a vital role in defect diffusion. We expect that this study would help accurately predict the dynamical processes at high temperatures. [ABSTRACT FROM AUTHOR]
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- 2023
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18. Fast low bias pulsed DC transport measurements for the investigation of low temperature transport effects in semiconductor devices.
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Fuchs, C., Hofer, M., Fürst, L., Shamim, S., Kießling, T., Buhmann, H., and Molenkamp, L. W.
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SEMICONDUCTOR devices , *TEMPERATURE effect , *LOW temperatures , *OHMIC resistance , *QUANTUM wells , *QUANTUM transitions - Abstract
We present a setup for fast, low-bias (≤ 1 mV) DC transport measurements with μs time resolution for high ohmic resistance (≈ 20 k Ω) semiconducting samples. We discuss the circuitry and instrumentation for the measurement approach that can be applied to any kind of semiconductor device or (gated) two-dimensional material and demonstrate the main measurement artifacts in typical measurements by means of circuit simulation. Based on the latter, we present a simple two-step protocol for eliminating the measurement artifacts reliably. We demonstrate the technique by measuring the transitions between quantum Hall plateaus in the HgTe quantum wells and resolve plateaus as short-lived as 100 μs. [ABSTRACT FROM AUTHOR]
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- 2023
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19. Charge carrier dynamics in conducting polymer PEDOT using ab initio molecular dynamics simulations.
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Zahabi, Najmeh, Baryshnikov, Glib, Linares, Mathieu, and Zozoulenko, Igor
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CHARGE carriers , *MOLECULAR dynamics , *CONDUCTING polymers , *CHEMICAL bond lengths , *TEMPERATURE effect , *ELECTRONIC equipment - Abstract
As conducting polymers become increasingly important in electronic devices, understanding their charge transport is essential for material and device development. Various semi-empirical approaches have been used to describe temporal charge carrier dynamics in these materials, but there have yet to be any theoretical approaches utilizing ab initio molecular dynamics. In this work, we develop a computational technique based on ab initio Car–Parrinello molecular dynamics to trace charge carrier temporal motion in archetypical conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT). Particularly, we analyze charge dynamics in a single PEDOT chain and in two coupled chains with different degrees of coupling and study the effect of temperature. In our model we first initiate a positively charged polaron (compensated by a negative counterion) at one end of the chain, and subsequently displace the counterion to the other end of the chain and trace polaron dynamics in the system by monitoring bond length alternation in the PEDOT backbone and charge density distribution. We find that at low temperature (T = 1 K) the polaron distortion gradually disappears from its initial location and reappears near the new position of the counterion. At the room temperature (T = 300 K), we find that the distortions induced by polaron, and atomic vibrations are of the same magnitude, which makes tracking the polaron distortion challenging because it is hidden behind the temperature-induced vibrations. The novel approach developed in this work can be used to study polaron mobility along and between the chains, investigate charge transport in highly doped polymers, and explore other flexible polymers, including n-doped ones. [ABSTRACT FROM AUTHOR]
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- 2023
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20. Ultra-high temperature Soret effect in a silicate melt: SiO2 migration to cold side.
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Nishida, Yuma, Shimizu, Masahiro, Okuno, Tatsuya, Matsuoka, Jun, Shimotsuma, Yasuhiko, and Miura, Kiyotaka
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THERMOPHORESIS , *TEMPERATURE effect , *MOLECULAR volume , *EARTH sciences , *MOLECULAR dynamics - Abstract
The Soret effect, temperature gradient driven diffusion, in silicate melts has been investigated intensively in the earth sciences from the 1980s. The SiO2 component is generally concentrated in the hotter region of silicate melts under a temperature gradient. Here, we report that at ultra-high temperatures above ∼3000 K, SiO2 becomes concentrated in the colder region of the silicate melts under a temperature gradient. The interior of an aluminosilicate glass [63.3SiO2–16.3Al2O3–20.4CaO (mol. %)] was irradiated with a 250 kHz femtosecond laser pulse for local heating. SiO2 migrated to the colder region during irradiation with an 800 pulse (3.2 ms irradiation). The temperature analysis indicated that migration to the colder region occurred above 3060 K. In the non-equilibrium molecular dynamics (NEMD) simulation, SiO2 migrated to the colder region under a temperature gradient, which had an average temperature of 4000 K; this result supports the experimental result. On the other hand, SiO2 exhibited a tendency to migrate to the hotter region at 2400 K in both the NEMD and experimental study. The molar volume calculated by molecular dynamics simulation without a temperature gradient indicates two bends at 1650 and 3250 K under 500 MPa. Therefore, the discontinuous (first order) transition with coexistence of two phases of different composition could be related to the migration of SiO2 to colder region. However, the detailed mechanism has not been elucidated. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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21. Occupancies of tetra- and octahedral sites in CoFe2O4 nanoparticles: The effect of the sintering temperature.
- Author
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Bilovol, Vitaliy, Sikora, Marcin, Lisníková, Soňa, Żukrowski, Jan, Berent, Katarzyna, and Gajewska, Marta
- Subjects
- *
TEMPERATURE effect , *RIETVELD refinement , *X-ray diffraction , *MOSSBAUER spectroscopy , *FERRITES , *X-ray absorption - Abstract
A temperature factor is one of the main parameters in the synthesis of nanoparticles and can affect considerably the arrangement of atoms in the lattice. In the system of magnetically hard CoFe2O4 spinel ferrite, the distribution of cations directly determines the magnetic properties of the sample. It was studied, on products of co-precipitation synthesis followed by a temperature dependent sinterization, by x-ray diffraction (XRD), x-ray absorption (XAS) using synchrotron radiation, vibrating sample magnetometry, and 57Fe Mössbauer spectroscopy (MS). From the Rietveld refinement of XRD patterns, the site occupancies reveal the following trend: with a decrease in the sintering temperature, the inversion degree parameter γ, which is a fraction of Co ions residing in the octahedral sites, decreases. For the highest sintering temperature explored in this work, 1000 °C, γ ≈ 0.83 giving rise to (Co0.17Fe0.83)A[Co0.83Fe1.27]BO4 formulation. For the lowest sintering temperature explored, 500 °C, the inversion degree is approximately 0.69 giving rise to (Co0.31Fe0.69)A[Co0.69Fe1.31]BO4 formulation. The propensity for the cationic arrangement was also confirmed by MS. Qualitative analysis of XAS at Co L3,2 edges strongly supports the tendency observed by XRD: the lower the sintering temperature, the more Co ions tend to occupy the tetrahedral sites. The magnetic behavior of the samples is consistent with the particle size which was determined by transmission/scanning electron microscopies. The particle size is the product of different sintering temperatures after the primary synthesis. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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22. A molecular dynamics approach to revealing effect mechanism of asphaltene on wax deposition behavior.
- Author
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Zhai, Shengbo, Cao, Guangsheng, Zuo, Songlin, YuJie, Bai, Cheng, QingChao, Zhang, Ning, Li, Dan, and Liu, Ying
- Subjects
- *
MOLECULAR dynamics , *PETROLEUM , *ASPHALTENE , *WAXES , *TEMPERATURE effect - Abstract
The complex structure of asphaltene itself leads to obvious precipitation and aggregation characteristics, and it interacts with wax molecules, thereby affecting the wax precipitation characteristics of waxy crude oil. To clarify the effect of asphaltene on wax deposition behavior, molecular dynamics simulations were conducted to analyze the aggregation behavior of wax molecules in waxy crude oil systems and the effect of asphaltene on wax deposition. Subsequently, dynamic wax deposition experiments were used to validate the simulation results, and the influence of asphaltene on wax deposition behavior was further discussed in conjunction with the simulation results. The results show that the lower the temperature of the crude oil system, the lower the cooling rate, and the higher the aggregation degree of wax molecules; As the concentration of asphaltene increases, the existence state of asphaltene will undergo a transition, with a concentration of 0.2 wt% asphaltene as the transition boundary. The aggregation of asphaltene molecules is mainly in the form of F-type stacking, and the presence of asphaltene weakens the structural strength of the wax deposition layer. On the other hand, the aggregated asphaltene hinders the growth of wax crystal clusters due to spatial hindrance; Increase the concentration of asphaltene in the model oil, when the asphaltene concentration is 0.2 wt%, the wax deposition rate reaches its maximum, which means that the asphaltene concentration will affect its existence state in the waxy crude oil system, thereby affecting the wax deposition behavior. And analyzed the effects of temperature and moisture content on wax deposition. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
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23. Continuous wave laser ablation for tailored titanium nanoparticle synthesis: temperature and liquid medium effects.
- Author
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Ali, Mubasher, Su, Zhou, Tan, Yuanfu, Lin, Feng, Liao, Wei-Hsin, and Wong, Hay
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- *
SURFACE charges , *NANOPARTICLE synthesis , *LASER ablation , *MOLECULAR structure , *TEMPERATURE effect , *SODIUM dodecyl sulfate - Abstract
We reported for the first time the generation of titanium (Ti) nanoparticles (NPs) in different liquids (deionized (DI) water and sodium dodecyl sulfate (SDS) solution) and at a range of temperatures (5 °C, 28 °C, 60 °C, and 80 °C) using continuous-wave high-power laser ablation in liquid (CWLAL). The CWLAL technique is a convenient and cost-effective way to generate NPs. The key outcomes of our investigation are the effects of temperature and the liquid mediums on the average size, generation rate, shape, surface charges, and crystallographic structure of the NPs. Generated NPs show consistent spherical shape regardless of liquid medium changes and temperature variation. SDS solution notably impacts NP size and generation rate with higher surface charges than DI water. For instance, at temperatures of 28 °C and 80 °C, the generation rates in SDS solution are 316 mg/hr and 309 mg/hr, with average NP sizes of 33 nm and 34 nm, respectively. In contrast, the generation rates in DI water are 96 mg/hr and 302 mg/hr, with NP sizes of 13 nm and 20 nm, respectively. The weaker crystallographic structure observed in NPs generated in SDS solution, compared to the more robust crystallographic structure of NPs synthesized in DI water. Liquid temperature plays a significant role in determining surface charges, average particle size, and molecular structure of NPs. The choice of the liquid medium and temperature can be critical for tailoring NP characteristics to specific applications. Ongoing work is being conducted to explore the possibilities of further progress in this area to generate efficient and customized NPs. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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24. Understanding the Temperature Effect on Carbon‐Carbon Coupling during CO2 and CO Electroreduction in Zero‐Gap Electrolyzers†.
- Author
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Zhuansun, Mengjiao, Wang, Xuan, Teng, Wenzhi, and Wang, Yuhang
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- *
TEMPERATURE effect , *MASS transfer , *HIGH temperatures , *THERMODYNAMICS , *ELECTROLYTIC cells , *ELECTROLYTIC reduction - Abstract
Comprehensive Summary: Cu‐catalyzed electrochemical CO2 reduction reaction (CO2RR) and CO reduction reaction (CORR) are of great interest due to their potential to produce carbon‐neutral and value‐added multicarbon (C2+) chemicals. In practice, CO2RR and CORR are typically operated at industrially relevant current densities, making the process exothermal. Although the increased operation temperature is known to affect the performance of CO2RR and CORR, the relationship between temperatures and kinetic parameters was not clearly elaborated, particularly in zero‐gap reactors. In this study, we detail the effect of the temperature on Cu‐catalyzed CO2RR and CORR. Our electrochemical and operando spectroscopic studies show that high temperatures increase the activity of CO2RR to CO and CORR to C2H4 by enhancing the mass transfer of CO2 and CO. As the rates of these two processes are highly influenced by reactant diffusion, elevating the operating temperature results in high local CO2 and CO availability to accelerate product formation. Consequently, the *CO coverage in both cases increases at higher temperatures. However, under CO2RR conditions, *CO desorption is more favorable than carbon‐carbon (C—C) coupling thermodynamically at high temperatures, causing the reduction in the Faradaic efficiency (FE) of C2H4. In CORR, the high‐temperature‐augmented CO diffusion overcomes the unfavorable adsorption thermodynamics, increasing the probability of C—C coupling. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
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25. Understanding the Temperature Effect on Carbon‐Carbon Coupling during CO2 and CO Electroreduction in Zero‐Gap Electrolyzers†.
- Author
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Zhuansun, Mengjiao, Wang, Xuan, Teng, Wenzhi, and Wang, Yuhang
- Subjects
TEMPERATURE effect ,MASS transfer ,HIGH temperatures ,THERMODYNAMICS ,ELECTROLYTIC cells ,ELECTROLYTIC reduction - Abstract
Comprehensive Summary: Cu‐catalyzed electrochemical CO2 reduction reaction (CO2RR) and CO reduction reaction (CORR) are of great interest due to their potential to produce carbon‐neutral and value‐added multicarbon (C2+) chemicals. In practice, CO2RR and CORR are typically operated at industrially relevant current densities, making the process exothermal. Although the increased operation temperature is known to affect the performance of CO2RR and CORR, the relationship between temperatures and kinetic parameters was not clearly elaborated, particularly in zero‐gap reactors. In this study, we detail the effect of the temperature on Cu‐catalyzed CO2RR and CORR. Our electrochemical and operando spectroscopic studies show that high temperatures increase the activity of CO2RR to CO and CORR to C2H4 by enhancing the mass transfer of CO2 and CO. As the rates of these two processes are highly influenced by reactant diffusion, elevating the operating temperature results in high local CO2 and CO availability to accelerate product formation. Consequently, the *CO coverage in both cases increases at higher temperatures. However, under CO2RR conditions, *CO desorption is more favorable than carbon‐carbon (C—C) coupling thermodynamically at high temperatures, causing the reduction in the Faradaic efficiency (FE) of C2H4. In CORR, the high‐temperature‐augmented CO diffusion overcomes the unfavorable adsorption thermodynamics, increasing the probability of C—C coupling. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
26. New Double Perovskite Solar Cell Containing Ba3PCl3 (A3BX3) and CsSnI3 (ABX3) Leading to an Improved Efficiency Above 30%.
- Author
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Rahman, Mahabur, Lubaba, Afifa, Irfan, Ahmad, and Rahman, Md. Ferdous
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- *
SOLAR cells , *DOPING agents (Chemistry) , *OPTICAL properties , *TEMPERATURE effect , *HALIDES - Abstract
In photovoltaic (PV) technology, halide perovskites stand out for their exceptional optical properties, improved performance, and cost‐effectiveness. This study utilized SCAPS‐1D to examine a novel dual absorber solar cell, using Ba3PCl3 as the top absorber and CsSnI3 as the bottom absorber, marking the first comprehensive analysis of this pairing. The research thoroughly investigated the thickness, doping concentrations, and defect densities of each absorber to evaluate their impact on electrical properties such as VOC, JSC, FF, and power conversion efficiency (PCE). Additionally, the study meticulously analyzed the effects of temperature, shunt, and series resistances. The results show that the first device (FTO/SnS2/Ba3PCl3/Au) achieved a PCE of 17.75%, while the second device (FTO/SnS2/CsSnI3/Au) reached a PCE of 20.63%. Optimized designs combining both absorbers (FTO/SnS2/Ba3PCl3/CsSnI3/Au) resulted in a PCE of 30.97%, with a JSC of 47.52 mA/cm2, FF of 80.42%, and VOC of 0.81 V. These promising findings offer valuable insights for the future development of experimental solar devices. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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27. Impact of Slice Thickness and Baking Temperature on the Physicochemical Quality and Nutritional Properties of Newly Developed Baked Coconut Chips.
- Author
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Pandiselvam, R., Krishnan, Rupa, Manikantan, M. R., Jacob, Anjitha, Ramesh, S. V., Beegum, Shameena, and Aamer, Rai
- Subjects
- *
ENTHALPY , *COCONUT , *MANUFACTURING processes , *PRODUCT quality , *TEMPERATURE effect - Abstract
Due to rising health concerns, consumers are increasingly inclined toward reduced‐fat products, which have driven the need for nutritious alternatives through modifications in recipes and production processes. Despite the growing popularity of coconut‐based products, there is limited research on baked coconut chips, particularly regarding the effects of baking temperatures and product thicknesses. This study addresses this gap by developing baked coconut chips samples (BCSs) as a healthier alternative to traditional fried chips. Baking experiments were conducted at temperatures of 140°C, 160°C, and 180°C, with 160°C identified as optimal for balancing processing time and product quality. The study also compared baked coconut chips with those that were dried and then baked (dried baked coconut chips samples [DBCS]). Among the trials, the 0.5‐mm‐thick coconut chips baked at 160°C exhibited favorable sensory attributes and notable biochemical properties, including 3.13% moisture content, 1.13% ash, 40.49% fat, and significant antioxidant activity. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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28. Temperature Effects on the Distribution of Aragonitic and Calcite‐Secreting Epifaunal Bivalves.
- Author
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Eichenseer, Kilian, Balthasar, Uwe, Smart, Christopher W., and Kiessling, Wolfgang
- Subjects
- *
SEASONAL temperature variations , *TEMPERATURE distribution , *WATER temperature , *COLD (Temperature) , *TEMPERATURE effect - Abstract
ABSTRACT Aim Location Taxa Methods Results Main Conclusions Significance To test if temperature significantly influences the global biogeographic distribution of marine epifaunal bivalves via their skeletal mineralogy.Global.Marine, epifaunal bivalves.The skeletal mineralogy of 45,789 epifaunal bivalve occurrences from 669 species from the Ocean Biodiversity Information System (OBIS) was related to sea surface temperatures from Bio‐ORACLE. Binomial regression was used to assess the influence of temperature and seasonality on the distribution of aragonitic and calcite‐secreting bivalve occurrences, aggregated in equal‐area grid cells.The proportion of aragonitic bivalve occurrences significantly increases with mean annual temperature in our global analysis and most marine biogeographic realms. A greater prevalence of calcite‐secreting bivalves in seasonal climates could be shown at low mean annual temperatures at the global scale but not within biogeographic realms.The global biogeographic distribution of epifaunal bivalves is significantly influenced by water temperature via their skeletal mineralogy. The mechanism driving this pattern is best explained by the temperature modulation of the effect of Mg2+ on calcite growth. Although this Mg2+ effect predicts an advantage for aragonite secretion at higher temperatures, poleward migration in response to higher temperature extremes will expose tropical taxa to cooler temperatures in the cold season, which may impede aragonite secretion in taxa not adapted to these climates.Our results suggest that skeletal mineralogy is likely to influence ocean warming‐induced migration patterns. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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29. A Study of the Effect of Temperature on the Capacitance Characteristics of a Metal- μ hemisphere Resonant Gyroscope.
- Author
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Yao, Xiangxian, Zhao, Hui, Su, Zhong, Gu, Xibing, and Chu, Sirui
- Abstract
Metal- μ hemispherical resonant gyros (M- μ HRGs) are widely used in highly dynamic navigation systems in extreme environments due to their high accuracy and structural stability. However, the effect of temperature variations on the capacitance characteristics of M- μ HRGs has not been fully investigated, which is crucial for optimizing the performance of the gyro. This study aims to systematically analyze the effect of temperature on the static and dynamic capacitances of M- μ HRGs. In this study, an M- μ HRG structure based on a 16-tooth metal oscillator is designed, and conducted simulation experiments using non-contact capacitance measurement method and COMSOL Multiphysics 6.2 finite element simulation software in the temperature range of 233.15 K to 343.15 K. The modeling analysis of the static capacitance takes into account the thermal expansion effect, and the results show that static capacitance remains stable across the measured temperature range, with minimal effect from temperature. The dynamic capacitance exhibits significant nonlinear variations under different temperature conditions, especially in the two end temperature intervals (below 273.15 K and above 313.15 K), where the capacitance values show local extremes and fluctuations. In order to capture this nonlinear behavior, the experimental data were smoothed and fitted using the LOESS method, revealing a complex trend of the capacitance variation with temperature. The results show that the M- μ HRG has good capacitance stability in the mid-temperature range, but its dynamic performance is significantly affected at extreme temperatures. This study provides a theoretical reference for the optimal design of M- μ HRGs in high- and low-temperature environments. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
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30. Study on a Pseudo-Elastic Model for High-Damping Rubber.
- Author
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Guo, Zhihao and Peng, Tianbo
- Subjects
- *
STRAINS & stresses (Mechanics) , *CONTINUUM mechanics , *REGRESSION analysis , *MATERIALS testing , *TEMPERATURE effect - Abstract
With advancements in seismic isolation and damping technology, high-damping rubber (HDR) bearings are now widely used. However, significant gaps remain in HDR-analysis model research, with few studies integrating multiple factors, the Mullins effect, and stiffness hardening for more accurate practical predictions. This study classifies the effective behavior of HDR and examines the stress–strain relationships of different behavioral types using more appropriate equations. Mathematical models were established based on pseudo-elasticity theory, which is an extension of continuum mechanics. Subsequently, parameter functions were developed through parameter determination tests and regression analysis, leading to the completion of the pseudo-elastic model for HDR. Finally, the model's effectiveness was validated through validation tests. This study finds that behavior classification effectively examines phenomenological-based HDR stress–strain relationships, as distinct behavioral patterns are not adequately captured by a single approach. Incorporating tests to functionalize material parameters complements theoretical models. Additionally, accurately explaining HDR behavior requires considering the Mullins effect and stiffness hardening, influenced by the coupled effects of temperature, strain amplitude, and compressive stress. Consequently, this HDR pseudo-elastic model offers a comprehensive explanation of HDR behavior, including the Mullins effect and stiffness hardening, under various influencing factors based on clear mechanical principles and explicit computational procedures. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
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31. Energy Recovery from Municipal Sewage Sludge: Combustion Kinetics in a Varied Oxygen–Carbon Dioxide Atmosphere.
- Author
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Bień, Jurand and Bień, Beata
- Subjects
- *
ACTIVATION energy , *CONTRAST effect , *CARBON dioxide , *RATE coefficients (Chemistry) , *TEMPERATURE effect - Abstract
Energy from municipal sewage sludge can be obtained by applying a thermal conversion method. In this study, the combustion kinetics of municipal sewage sludge were analyzed in an O2/CO2 atmosphere. Studies were conducted in different gaseous atmospheres consisting of varying proportions of oxygen and carbon dioxide. The participation of oxygen was as follows: 20, 40, 60, 80 and 100% vol. The experimental temperatures varied from 873 to 1273 K. The experimentally obtained results helped establish the basic kinetic parameters, such as the reaction order n, factor Ko and activation energy Ea of sludge grains. The values of the activation energy Ea and Ko were, respectively, 46 kJ/mol and 0.0127 mg/m2sPa. They show that the limiting factor of combustion is the diffusion of oxygen and that combustion reactions take place in the outer layer of the unreacted core. Therefore, sludge is promising for energy recovery because it has quite a high net calorific value (NCV) and a high gross calorific value (GCV). The GCV was 14.1 MJ/kg and the NCV was 12.8 MJ/kg. The experimental studies with a wide range of process parameters helped to create an array of apparent reaction rates as a function of the temperature and oxygen concentration, showing the significant effect of oxygen on the apparent reaction rate, in contrast to the effect of temperature. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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32. Effect of Temperature and Electric Field Strength on Carrier Mobility of Oil-Impregnated Pressboard Under DC Voltage.
- Author
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Deng, Jun, Xie, Zhicheng, Ge, Hao, Xue, Xiaoqiang, Gao, Chunjia, Cheng, Jianwei, Zhou, Haibin, Pan, Zhicheng, Lyu, Gang, and Wu, Heng
- Subjects
- *
CHARGE carrier mobility , *ELECTRIC field effects , *ELECTRIC insulators & insulation , *SURFACE potential , *CARDBOARD - Abstract
The influence of carrier mobility on the space charge transport behavior inside the oil-impregnated pressboard insulation of converter transformers cannot be neglected. However, at present, current knowledge is usually derived from empirical or theoretical values, lacks experimental studies, and often ignores the effects of temperature and field strength under actual operating conditions. In this paper, based on the variable-temperature surface potential decay (SPD) method, a carrier mobility measurement platform for oil-impregnated pressboard is established, and the carrier mobility values for different combinations of oil and oil-impregnated pressboard are obtained experimentally to analyze and reveal the influence mechanisms of temperature and field strength on the carrier mobility. The results indicate the following: (1) The positive and negative carrier mobilities of oil-impregnated pressboard are in the range of 10−12–10−13 m2·V−1·s−1, and the negative carrier mobility is always higher than the positive carrier mobility. (2) The carrier mobility is positively correlated with the changes of temperature and field strength, and when the temperature increases from 20 °C to 80 °C, the positive and negative carrier mobilities increase by 4.01 times and 4.72 times, respectively; when the field strength increases from 1 kV/mm to 7 kV/mm, the positive and negative carrier mobility increases by 2.53 and 2.72 times, respectively. (3) The carrier mobility of the pressboard with a higher oil absorption rate changes more significantly with temperature; when the field strength is 7 kV/mm and the temperature increases from 20 °C to 80 °C, the positive polarity carrier mobility increases from 3.96 × 10−13 m2·V−1·s−1 to 2.64 × 10−11 m2·V−1·s−1, an increase of 66.67 times, while the increase in the carrier mobility of the pressboard with a lower oil absorption rate is only 1.59 times. (4) The carrier mobility of the naphthenic transformer oil-impregnated pressboard is higher than that of the paraffin-based transformer oil-impregnated pressboard, and the carrier mobility of two kinds of naphthenic transformer oil-impregnated pressboard is 3.16 times and 2.47 times higher than that of the paraffin-based transformer oil-impregnated pressboard, respectively, under the conditions of 60 °C and 7 kV/mm. (5) Utilizing the Darcy model and microscopic scanning results of the pressboard morphology, it was revealed that permeability and fiber structure are key factors influencing the variation in carrier mobility. The research results of this paper can provide theoretical basis for the calibration and optimization of the oil-pressboard insulation structure of converter transformers. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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33. Magnetic Memory Effects in BaFe 2 (As 0.68 P 0.32) 2 Superconducting Single Crystal.
- Author
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Badea, Alina M., Ivan, Ion, Miclea, Corneliu F., Crisan, Daniel N., Galluzzi, Armando, Polichetti, Massimiliano, and Crisan, Adrian
- Subjects
- *
CRITICAL currents , *SINGLE crystals , *TEMPERATURE effect , *CRITICAL temperature , *COOLING , *IRON-based superconductors - Abstract
Among many iron-based superconductors, isovalently substituted BaFe2(As1−xPx)2 displays, for x ≈ 0.3, apart from the quite usual Second Magnetization Peak (SMP) in the field dependence of the critical current density, an unusual peak effect in the temperature dependence of the critical current density in the constant field, which is related to the rhombic-to-square (RST) structural transition of the Bragg vortex glass (BVG). By using multi-harmonic AC susceptibility investigations in three different cooling regimes—field cooling, zero-field cooling, and field cooling with measurements during warming up—we have discovered the existence of a temperature region in which there is a pronounced magnetic memory effect, which we attributed to the direction of the structural transition. The observed huge differences in the third harmonic susceptibility at low and high AC frequencies indicates the difference in the time-scale of the structural transition in comparison with the timescale of the vortex excitations. Our findings show that the RST influence on the vortex dynamics goes beyond the previously observed influence on the onset of the SMP. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
34. Relative Radiometric Correction Method Based on Temperature Normalization for Jilin1-KF02.
- Author
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Huang, Shuai, Yang, Song, Bai, Yang, Sun, Yingshan, Zou, Bo, Wu, Hongyu, Zhang, Lei, Li, Jiangpeng, and Yang, Xiaojie
- Subjects
- *
ACHROMATISM , *RADIOMETRIC methods , *STANDARD deviations , *TEMPERATURE effect , *OPTICAL sensors - Abstract
The optical remote sensors carried by the Jilin-1 KF02 series satellites have an imaging resolution better than 0.5 m and a width of 150 km. There are radiometric problems, such as stripe noise, vignetting, and inter-slice chromatic aberration, in their raw images. In this paper, a relative radiometric correction method based on temperature normalization is proposed for the response characteristics of sensors and the structural characteristics of optical splicing of Jilin-1 KF02 series satellites cameras. Firstly, a model of temperature effect on sensor output is established to correct the variation of sensor response output digital number (DN) caused by temperature variation during imaging process, and the image is normalized to a uniform temperature reference. Then, the horizontal stripe noise of the image is eliminated by using the sensor scan line and dark pixel information, and the vertical stripe noise of the image is eliminated by using the method of on-orbit histogram statistics. Finally, the method of superposition compensation is used to correct the vignetting area at the edge of the image due to the lack of energy information received by the sensor so as to ensure the consistency of the image in color and image quality. The proposed method is verified by Jilin-1 KF02A on-orbit images. Experimental results show that the image response is uniform, the color is consistent, the average Streak Metrics (SM) is better than 0.1%, Root-Mean-Square Deviation of the Mean Line (RA) and Generalized Noise (GN) are better than 2%, Relative Average Spectral Error (RASE) and Relative Average Spectral Error (ERGAS) are greatly improved, which are better than 5% and 13, respectively, and the relative radiation quality is obviously improved after relative radiation correction. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
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35. Mutual impact of temperature and voltage on electro-osmotic dewatering process of mine tailings – a numerical study.
- Author
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Hamidi, Amir, Sheikhy, Farzad, and Asemi, Farhad
- Subjects
- *
ELECTRIC currents , *VOLTAGE , *TEMPERATURE effect , *ELECTRO-osmosis , *POROSITY - Abstract
AbstractTemperature and voltage are critical operational parameters that significantly influence the efficiency of the electro-osmosis dewatering process. Despite their importance, there is a lack of comprehensive research to evaluate their combined effects on enhancing electro-osmotic dewatering process efficiency. In this study, mutual effects of temperature and voltage on electro-osmotic dewatering of tailings were investigated using numerical simulation. To validate the model, output data were compared with experimental results on thermal electro-osmotic dewatering of red mud. The results indicated that increase in temperature from 25 °C to 35 °C and 25 °C to 45 °C resulted in a 12% and 27% increase in electric current, and 25% and 50% increase in fluid outflow velocity, respectively. Additionally, electric current and fluid outflow velocity increased by about 50% and 100% for all considered temperatures when voltage increased from 10.5 V to 15.75 and 10.5 V to 21 V, respectively. Furthermore, the results proved that increase in temperature was more effective than voltage in enhancing Joule’s heating-induced dewatering. The study also revealed that increase in distance between electrodes by more than 1 m decreases the efficiency of electro-osmotic dewatering. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
36. Experimental determination of tin partitioning between titanite, ilmenite, and granitic melts using improved capsule designs.
- Author
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Huang, Fangfang, Wang, Jintuan, Xiong, Xiaolin, Gao, Mingdi, Li, Li, and Wei, Chunxia
- Subjects
- *
PRECIOUS metals , *SPHENE , *ILMENITE , *ALLOYS , *TEMPERATURE effect - Abstract
Investigating mineral/melt Sn partitioning at high temperatures and pressures is a difficult task because Sn is a redox-sensitive multivalent element and easily alloys with noble metal sample capsules. To obtain accurate Sn partition coefficients between titanite, ilmenite, and granitic melts, we developed single capsule Pt or Au and double capsule Pt95Rh5 (or Au)-Re designs to avoid significant Sn loss at a controlled oxygen fugacity (fO2). With these new capsule designs, we performed piston-cylinder experiments of Sn partitioning between titanite, ilmenite, and granitic melts. The experimental P-T-fO2 conditions were 0.5–1.0 GPa, 850–1000 °C, and ~QFM+8 to ~QFM-4 (quartz-fayalite-magnetite, QFM, buffer), with fO2 controlled by the solid buffers of Ru-RuO2, Re-ReO2, Co-CoO, graphite, and Fe-FeO. The obtained mineral/melt Sn partition coefficients ( D S n m i n / m e l t ) are 0.48–184.75 for titanite and 0.03–69.45 for ilmenite at the experimental conditions. The D S n m i n / m e l t values are largely dependent on fO2, although the effects of temperature and melt composition are also observed. D S n T t n / m e l t strongly decreases with decreasing fO2, from ~46–185 at the most oxidizing conditions (Ru-RuO2 buffer), to ~2–16 at moderately oxidizing to moderately reducing conditions (Re-ReO2 to Co-CoO and graphite buffers), to < 1 at the most reducing conditions (Fe-FeO buffer). D S n I l m / m e l t exhibits a variation trend similar to D S n T t n / m e l t but is always lower than D S n T t n / m e l t at a given fO2. These D S n m i n / m e l t values can be applied to quantitatively assess the mineralization potential of granitic magmas. Using D S n T t n / m e l t , we estimate that Sn contents are ~150–400 ppm in the pre-mineralization magmas of the tin-mineralized Qitianling plutons (South China). [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
37. Statistical optimization and sequential scale-up of α-galactosidase production by Actinoplanes utahensis B1 from shake flask to pilot scale.
- Author
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John Babu, D., Balumahendra, K., Venkateswarulu, T.C., and Sathish, T.
- Subjects
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TEMPERATURE effect , *GALACTOSE , *INDUSTRIAL applications , *FERMENTATION , *SECRETION - Abstract
α-Galactosidase (α-GAL) is a class of hydrolase that releases galactose from galacto-oligosaccharides and synthetic substrates such as pNPG. In this study, the production of α-GAL by Actinoplanes utahensis B1 in submerged fermentation was enhanced by using statistical methods. The effects of temperature, pH, and inoculum percentage on enzyme secretion were optimized using BBD of RSM. The optimized process was scaled up from the shake flask to the laboratory scale (5 L) and to pilot scale (30 L) using KLa based scale-up strategy. By using BBD, a maximum yield of 62.5 U/mL was obtained at a temperature of 28 °C, a pH of 6.9, and an inoculum of 6.4%. Scale-up was performed successfully and achieved a yield of 74.4 U/mL and 76.8 U/mL in laboratory scale and pilot scale fermenters. The TOST was performed to validate the scale-up strategy and the results showed a confidence level of 95% for both scales indicating the perfect execution of scale-up procedure. Through the implementation of BBD and scale-up strategy, the overall enzyme yield has been significantly increased to 76%. This is the first article to explore the scale-up of α-GAL from the A. utahensis B1 strain and provide valuable insights for industrial applications. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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38. Two-species model for nonlinear flow of wormlike micelle solutions. Part II: Experiment.
- Author
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Salipante, Paul F., Cromer, Michael, and Hudson, Steven D.
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VISCOSITY solutions , *SHEARING force , *TEMPERATURE effect , *VISCOSITY , *PREDICTION models , *MEASUREMENT of viscosity - Abstract
Applications often expose wormlike micelle solutions to a very wide range of shear and temperature conditions. The two-species model presented in Part I [Salipante et al., J. Rheol. 68 (2024)] describes the nonlinear rheology over a wide range of shear rates. Here, we compare the model predictions to measurements using a combination of microcapillary and rotational rheology to measure the viscosity of surfactant solutions across seven decades of shear rate and five decades of viscosity. The effect of temperature is studied between 20 and 60 ° C for different surfactant concentrations. Model parameters are determined from both small-amplitude shear measurements and fitting to the nonlinear data. Under shear stress, the model predicts due to hindered combination kinetics that the average micelle length decreases from several micrometers to a few hundred nanometers. At sufficiently high stress, the micelle shear rheology exhibits a transition from entangled wormlike behavior to a dilute rod rheology in agreement with the model. Transient stress-growth measurements exhibit a large overshoot, which is rather well predicted by the model with hindered combination rate. Microcapillary flow birefringence also is adequately predicted by the model, confirming the accuracy of its predicted micelle lengths and exhibiting a marked change in stress-optic response at the transition between entangled polymers and dilute rods. The relaxation of retardance after flow cessation follows model predictions that include micelle-micelle interactions, which are sensitive to the rotational diffusivity and length. These methods can be applied broadly to explore relationships between composition and performance. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
39. A 2DEG‐Based GaN‐on‐Si Terahertz Modulator with Multi‐Mode Switchable Control.
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Chen, Shanri, Duan, Siyu, Zou, Yongtu, Zhou, Shaolin, Wu, Jingbo, Jin, Biaobing, Zhu, Haoshen, Che, Wenquan, and Xue, Quan
- Subjects
- *
TWO-dimensional electron gas , *WIRELESS communications , *DATA warehousing , *TEMPERATURE effect , *STRUCTURAL design - Abstract
As terahertz (THz) technology has been widely considered as a key candidate for future sixth‐generation wireless communication networks, THz modulators show profound significance in wireless communication, data storage, and imaging. In special, dynamic tuning of THz waves through 2D electron gas (2DEG) incorporated with a hybrid design of metasurface has attracted keen interest due to the combined merits of deliberate structural design, rapid switching speed and the process compatibility. Current meta‐modulator enables very high modulation depth but encounter limited bandwidth. In this paper, by taking into account the co‐functional effects of temperature and voltage‐dependent dynamic control on transmission amplitude, a 2DEG‐based GaN‐on‐Si modulator with two switchable operational states (or four modes) of active wave control is proposed. Under cryogenic temperature conditions, the proposed device exhibits prominent 2D plasmons characteristics with switchable transitions between the gated mode and ungated mode for active control. Under room temperature conditions, the proposed device exhibits non‐resonance broadband spectra characteristics with tunable transitions between the linearity mode and depletion mode for transmission control. The scheme provides an option for the development of the actively tunable THz meta‐modulator and paves a way for the robust multifunctionality of electrically controllable THz switching, and biosensors. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
40. Effect of Drying Time and Frying Conditions on the Quality of Pork Rinds by Response Surface Methodology.
- Author
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Wang, Shang‐Ta, Lin, Hong‐Ting Victor, Syu, Yu‐Jin, and Sung, Wen‐Chieh
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RESPONSE surfaces (Statistics) , *PORK processing , *PROCESS optimization , *TEMPERATURE effect , *PORK - Abstract
ABSTRACT Fried pork rind, a processed pork by‐product, is popular as a snack globally, prized for its distinctive flavor and crisp texture achieved through frying. Although various studies have examined processing factors such as thickness, moisture content, and brine concentration, there is a scarcity of research addressing the effect of frying temperature on the quality of fried pork rinds. In the present study, the effects of varying hot air drying times (12, 18, and 24 h at 50°C), traditional deep‐fat frying temperatures (180°C, 195°C, and 210°C), and frying durations (3, 4, and 5 min) on the oil content, moisture content, breaking force, color, puffing ratio, and microstructural appearance of pork rinds were evaluated. The results revealed a significant correlation between frying temperature and time with the oil content of the pork rinds. The oil content and puffing ratio peaked at approximately 195°C. Moreover, the breaking force of the pork rinds decreased with increased frying time at 180°C, while the opposite trend was observed at 210°C. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
41. Nanoemulsions stabilized by nonionic surfactants to promote spontaneous imbibition in ultra-low permeability reservoirs: performance evaluation and mechanism study.
- Author
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Wu, Da, Liu, Dexin, Xu, Jiaju, Zhao, Han, Dong, Yeliang, and Adnan Massawe, Neema
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- *
NONIONIC surfactants , *WETTING , *TEMPERATURE effect , *SALINITY , *PERMEABILITY , *INTERFACIAL tension - Abstract
Nano-emulsions stabilized by nonionic surfactants have the characteristics of ultra-low interfacial tension (IFT) and altered wettability in ultra-low permeability reservoirs. Thus, in this work, a new nanoemulsion is proposed to enhance spontaneous imbibition recovery in ultra-low permeability reservoirs. The nanoemulsion is prepared using n-dodecane, Tween-20, and coconut oil acid diethanolamine n-amyl alcohol. The effects of temperature and salinity on particle size, IFT, and wettability alteration performance of the nanoemulsions were systematically studied. Experimental results show that the particle size of nanoemulsions increases with salinity, and the highest level is up to 100 nm, while an increase in temperature is beneficial to the formation of smaller nanoemulsions. The IFT of the nanoemulsion system can be reduced to an ultra-low level (10–3 mN/m) when the salinity is lower than 50,000 mg/L. As for the wettability alteration property of a nanoemulsion system, an increase in temperature can improve its performance, but variations in salinity seldom have any effects. At 56 °C and 30,000 mg/L salinity, the spontaneous imbibition recovery of 1.00 wt% nanoemulsion can reach 53.8% under the synergistic effect of three mechanisms: extremely small droplet size, excellent wettability alteration performance, and ultra-low IFT. These three mechanisms work together to significantly improve the displacement efficiency of ultra-low-permeability reservoirs. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
42. A Study of Temperature Effect on the Dripping Mode of Electrohydrodynamic Atomization with Viscous Liquids.
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Wu, Honglei, Liu, Hailong, and Wang, Junfeng
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FREQUENCIES of oscillating systems , *MENISCUS (Liquids) , *VISCOSITY , *TEMPERATURE effect , *WORKING fluids - Abstract
Electrohydrodynamic atomization (EHDA) has advantages in producing fine uniform droplets with low energy consumption. In this work, the droplets generated by the EHDA under the dripping mode have been captured by a backlit high-speed imaging system under various liquid temperatures T (293–343 K) and electric Bond numbers BoE (0–0.75). The temperature-viscosity relationships of the working fluids (G20, G40, G50, and G66) were fitted by an Arrhenius-type model. The effects of BoE, We, and T on the dimensionless droplet limiting length l* and oscillation frequency f were investigated through extensive experiments. The experimental results show that the droplet limiting length elongated with the higher liquid viscosity. However, the oscillation frequency of the meniscus declines with the liquid viscosity. By the elevation of liquid temperatures, the droplet limiting length diminishes, but the oscillation frequency of the liquid meniscus accelerates. Coefficients to estimate the effects of the flow rate and the temperature on oscillation frequency are introduced into the classical theory of meniscus oscillation to develop a semi-empirical model. The proposed model could estimate oscillation frequency for the meniscus under various electric Bond numbers, Weber numbers, and temperatures. The prediction achieves good agreements with experimental results. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
43. Effect of Varying Temperatures on the Electrochemical Performance of Lithium‐Ion Batteries Using LiNi0.3Mn0.3Co0.3Ti0.1O2 Cathode Materials.
- Author
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Elong, Kelimah, Kasim, Muhd Firdaus, Badar, Nurhanna, Azahidi, Azira, and Osman, Zurina
- Subjects
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CATHODES , *TEMPERATURE effect , *HIGH temperatures , *COMBUSTION , *VOLTAGE - Abstract
LiNi1/3Mn1/3Co1/3O2 (NMC 111) materials show promise as cathodes for lithium‐ion batteries (LIBs). However, their widespread use is hampered by various technical challenges, including rapid capacity fading and voltage instability. The cathode materials synthesized using the combustion method were annealed at various temperatures ranging from 650 to 900 °C for 24 h. In this study, we identified an optimal annealing temperature of 750 °C for LiNi0.3Mn0.3Co0.3Ti0.1O2 (NMCT) materials. NMCT‐750 exhibits an initial discharge capacity of about 140.1 mAh g−1 and retains the capacity of 91 % after 30th cycles. The good performance of NMCT‐750 is directly attributed to reduced cation mixing and the establishment of a stable structure with small particle sizes. In contrast, higher annealing temperatures (850 °C) lead to a rapid increase in primary particle size and result in poor cycling stability. Therefore, NMCT‐750, annealed at 750 °C, holds great potential as a cathode material for the next generation of LIBs. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
44. Porous wood ceramics for CO2 adsorption: adsorption capacity, kinetics, isotherms and CO2/N2 selectivity.
- Author
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Wang, Xiulei, Guo, Xiurong, Jiang, Wenjun, Jia, Mingxu, Zhang, Wei, Hao, Zewei, Wang, Hanwen, Du, Danfeng, Zhang, Yanlin, and Qi, Zhanfeng
- Subjects
- *
WOOD , *ADSORPTION kinetics , *ADSORPTION isotherms , *ADSORPTION capacity , *TEMPERATURE effect - Abstract
The objective of this study was to produce hydrophobic porous wood ceramics as adsorbents for CO2 through the resin treatment of pine. The prepared samples underwent analysis using various methods to determine their structure and properties. An orthogonal experimental approach was employed to obtain adsorbents with optimal preparation process. The highest adsorption capacity was determined to be 1.36 mmol/g at a temperature of 30 ℃ and a CO2 concentration of 15 vol%. The effect of temperature on the microstructure of wood ceramics was studied by characterization. Increasing temperatures adversely affected the adsorption capacity. Nevertheless, the hydrophobic nature of wood ceramics resulted in little impact of humidity on CO2 absorption. The CO2 adsorption kinetics of wood ceramics were analyzed using kinetic studies, which demonstrated that the kinetics can be accurately fitted by both the pseudo-first-order and Avrami models. The findings of the adsorption isotherm analysis showed that the Langmuir model fit was optimal. Following 30 cycles of adsorption-desorption in the presence of simulated gas, the CO2 sorption capacity of the wood ceramics was maintained at over 90%. In terms of CO2/N2 selectivity, the wood ceramics showed a clear preference for CO2, especially at 30 °C, where the CO2/N2 selectivity ratio reached 24.50. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
45. Microbial Preservation Performance of Cold Storage Units Assessed by Modeling of Time–Temperature Data.
- Author
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Martínez Martínez, Enrique, Cortés, Andrés García, de la Cruz Quiroz, Reynaldo, Alejandro, José Guadalupe Ríos, Fagotti, Fabian, and Torres, J. Antonio
- Subjects
- *
COLD storage , *FOOD preservation , *TEMPERATURE effect , *ENERGY consumption , *CONFIDENCE intervals - Abstract
Globally, regulations focus on the energy use of cold chain units and not on their food preservation performance. Our hypothesis is that this reflects a lack of practical/science-based assessment protocols which is addressed in this work. About 3 million time–temperature values for fish fillets stored in the bottom drawer independently set at 0.0 °C and a peer-reviewed predictive model were used to assess the microbial preservation performance of a residential refrigerator operating at 5.0 °C. The temperature effect on the exponential growth rate of Pseudomonas spp. on fish fillets was used to generate a refrigerator preservation indicator (RPI) with values < 1, ~ 1, and > 1 describing excellent, acceptable, or poor microbial preservation performance, respectively. Experimental effects evaluated were refrigerator technology (single/variable speed compressor, SS/VS), ambient temperature (21.1/32.2 °C, LT/HT), refrigerator load (22.5/39 kg, RL/HL), and emulation of door openings during meal preparation. Deterministic RPI estimations for the VS compressor ranged from 1.28 to 1.71, while those for SS ranged from 1.13 to 1.24. Probabilistic estimations yielded confidence intervals also exceeding the desirable 1.0 value. Mean comparisons through Tukey's HSD identified p-values < 0.05 for all main effects; nonetheless, compressor technology was the most influential factor since the compressor × ambient temperature interaction was significant for both compressors and the compressor × food load interaction was significant for VS compressors. It is concluded that users of cold chain units would benefit from regulations covering energy use and preservation performance with the latter assessed by RPI determinations. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
46. The effect of coprecipitation and heating temperature on structural evolution and electrochemical performance of iron-based prussian blue analogs.
- Author
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Liu, Yuqing, Chu, Wencheng, Xu, Yaozu, Yuan, Zijian, Liu, Jiarui, Zhao, Haitao, Liu, Quan, and Zhang, Wu
- Subjects
- *
PRUSSIAN blue , *TEMPERATURE effect , *SODIUM ions , *ELECTROCHEMISTRY , *CITRATES - Abstract
Iron-based Prussian blue analogs (PBAs) are synthesized using a modified coprecipitation approach at different temperatures to study the effect of coprecipitation reaction temperature on structural and electrochemical performance. The experimental results showed that the iron-based PBAs transferred from the cubic structure to the monoclinic phase as the temperature increased from 5 °C to 60 °C, with the former exhibiting rich-in-boundary morphology and the latter showing a well-defined cubic shape. The electrochemical performance of the samples is closely related to the structure: the PBAs with monoclinic structures exhibit a higher charge/discharge specific capacity than those of PBAs with cubic structures. In addition, the samples are further treated at 270 °C, new phases are probed, and the charge/discharge specific capacity for the HT-PB-60 sample is significantly improved by more than 36.15%. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
47. Fabrication of Si3N4 ceramic balls by SPS method with SiC powder bed.
- Author
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Liang, Zhen‐Quan, Liang, Jia‐Ji, Yu, Jun‐Jie, Cai, Pei‐Bin, Guo, Wei‐Ming, and Lin, Hua‐Tay
- Subjects
- *
SPECIFIC gravity , *VICKERS hardness , *FRACTURE toughness , *TEMPERATURE effect , *MICROSTRUCTURE - Abstract
Spark plasma sintering (SPS) is an ultrafast sintering method for the preparation of ceramics and ceramic composites with simple geometrical shapes, with the combined application of uniaxial pressure. This study aims to propose an SPS densification method for Si3N4 ceramic balls without necessitating alterations to tools and equipment. The Si3N4 ceramic balls intended for sintering are positioned within a SiC powder bed inside the conventional die used in SPS. The study systematically investigates the effects of presintering temperature (1400°C, 1500°C, and 1600°C) and SPS temperature (1600°C, 1700°C, and 1800°C) on the sphericity, relative density, phase composition, microstructure, and mechanical properties of Si3N4 ceramic balls. Experimental findings reveal that Si3N4 ceramic balls exhibiting an optimal combination of sphericity (0.94 ± 0.02), relative density (98.4%), and mechanical properties (Vickers hardness: 17.5 ± 0.4 GPa, fracture toughness: 6.4 ± 0.1 MPa·m1/2) were successfully achieved at a pre‐sintering temperature and SPS temperature of 1600°C, coupled with the use of a SiC powder bed and SPS method. Consequently, the SPS method demonstrates its capability to fabricate Si3N4 ceramic balls with excellent performance. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
48. Substrate Moisture and Temperature Effects on Limestone Reaction Rate in a Peat-Based Substrate.
- Author
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Huang, Jinsheng and Fisher, Paul R.
- Subjects
- *
BIOCHEMICAL substrates , *TEMPERATURE effect , *PH effect , *LOW temperatures , *HIGH temperatures - Abstract
Lime reaction rate in a container substrate is influenced by temperature and moisture, which are factors that vary between batches of substrate during manufacturing, storage, and crop production. The effects of temperature and moisture on the duration required to achieve a stable substrate-pH are useful information for substrate companies and growers, as well as a key component when modeling lime reaction over time. The pH of a 70 peat : 30 perlite (by volume) substrate was quantified over time under a range of different storage temperature (1.9 to 33.3°C) and substrate volumetric water content (VWC, 0.168 to 0.568 L of H2O/L of substrate). The lime source was a horticultural dolomitic carbonate limestone screened to the fraction that passed through a 100 US mesh but was retained on a 200 US mesh (0.075–0.15 mm) incorporated at 2.67 g·L−1 of substrate. Experiments provided two data sets for calibration and validation. Lime reaction rate increased with increasing substrate temperature and substrate moisture level. The duration required to reach a target substrate-pH value of 6.0 was used to indicate 90% of maximum pH effect from lime. Duration varied from 4 days with the combined high temperature (20.6 and 33.3 °C) and high VWC (0.468 and 0.568 L H2O/L of substrate) to 53 days with low temperature (1.9 °C) and low VWC (0.168 L H2O/L of substrate) for the calibration data set. At an example low VWC of 0.168 L of H2O/L of substrate, the duration required to reach substrate-pH 6.0 at 1.9, 7.8, 10, 20.6, and 33.3°C was 53, 38, 34, 23, and 17 days, respectively. Similarly, if the temperature was held constant at 33.3°C, reducing VWC from 0.568 L H2O/L to 0.128 L H2O/L would decrease lime reaction rate from 100% to 21%, requiring five times the duration to reach an equilibrium pH. Results can be used to compare the relative effects of moisture and temperature on lime reaction rate for substrate manufacturers and growers. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
49. Molecular-Level Analysis of Oxygen and Asphalt Behavior on Aggregate Surfaces.
- Author
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Liu, Qi, Yi, Xiaoying, Li, Yao, Cai, Mingmao, Zhang, Xiaoyu, Liu, Jinzhou, Yu, Bin, and Cannone Falchetto, Augusto
- Subjects
- *
RADIAL distribution function , *MOLECULAR dynamics , *MOLECULAR structure , *DIFFUSION coefficients , *TEMPERATURE effect , *ASPHALT - Abstract
The diffusion of oxygen molecules significantly influence the rate and extent of asphalt's oxidative aging. This research delves into the dynamic diffusion of oxygen within asphalt, examining the effects of temperature, water, aggregate types, and oxygen concentration. It establishes models for the mixed diffusion of oxygen and asphalt molecules and layered diffusion models for oxygen/(water) asphalt (aggregate) to simulate the dispersion processes of oxygen molecules within and into asphalt. Molecular dynamics simulations uncover the subtle interplay of these factors on oxygen distribution and their impact on asphalt's oxidative aging. By analyzing the molecular dynamics parameters (relative concentration, diffusion coefficient, and radial distribution function) of molecular structures within the model, the study reveals that, unlike diffusion in a vacuum, oxygen diffusion in asphalt follows a quadratic function with temperature changes. The presence of moisture decreases the concentration of oxygen within the asphalt, potentially reducing the degree of oxidation. Aggregates exhibit adsorption effects on oxygen and asphalt components, with their properties also influencing molecular mobility patterns. Oxygen accumulation at the aggregate/asphalt interface may increase the risk of damage. This research contributes to a deeper understanding of oxygen diffusion behavior during asphalt's oxidative aging process, offering insights for improving asphalt durability and developing antioxidants through managing oxygen diffusion. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
50. A Predictive Model for Estimation of the Degree of Reclaimed Asphalt Pavement Bitumen Activity.
- Author
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Tavva, Tejaswini Lakshmi, Arjun, P. V., and Reddy, Kusam Sudhakar
- Subjects
- *
ASPHALT pavement recycling , *BITUMEN , *TEMPERATURE effect , *PREDICTION models , *REGRESSION analysis - Abstract
The proportion of reclaimed asphalt pavement (RAP) bitumen that gets activated and coats the virgin aggregate during the initial stage of plant production of RAP mixes, in which the RAP material is initially mixed with superheated virgin aggregate, designated as the degree of RAP bitumen activity (DoA), is an important parameter influencing the quality and performance of the RAP mix. DoA is influenced by a variety of mix and process parameters. This paper presents an empirical model, developed using the results from a previous experimental investigation and those obtained from the additional experiments conducted in the present investigation, for prediction of the DoA of RAP binder under varying combinations of mix and process variables. The experimental investigation involved mixing separately identifiable size fractions of RAP material (1.18 to 4.75 mm) and virgin aggregate (9.5 to 26.5 mm) and measuring the quantity of RAP bitumen transferred to virgin aggregate to estimate the DoA. The 41 sets of experimental data considered for the development of the empirical model covered different RAP material proportions (15% to 75%), RAP binder quality (softening point of 69°C to 78°C), RAP binder content (4.0% to 6.0%), mixing duration (0.5 to 3 min), mixing temperature (70°C to 180°C), and superheating temperature of virgin aggregate (155°C to 197.5°C). The gradation and shape of the RAP material used in different coating experiments were also different. Additional experiments were carried out in the present investigation to study the effect of superheating temperature of virgin aggregates. DoA decreased exponentially with RAP bitumen stiffness and RAP content, whereas it increased with mixing temperature, mixing time, RAP bitumen content, and the proportion of coarser RAP material. The superheating temperature of virgin aggregate did not affect DoA significantly. A regression model was developed for estimation of DoA with reasonable accuracy without having to carry out the coating experiments. Such a predictive model is useful for obtaining inputs for the estimation of the quality of final binder blend in the RAP mix. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
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