Temperature Region Research Articles

Terpene speciation: Analytical insights into the oxidation and pyrolysis of limonene and 1,8-cineole via molecular-beam mass spectrometry

Comprehensive speciation datasets for the stoichiometric oxidation and pyrolysis of the two monoterpenes limonene (C10H16) and 1,8-cineole (C10H18O) are measured in an atmospheric laminar flow reactor using electron-ionization molecular-beam mass spectrometry. This setup allows direct sampling from the reactive flow and preserves the actual gas composition. Furthermore, clear determination of the exact elemental composition of the formed species is possible with the used time-of-flight mass spectrometer. Limonene is a monocyclic terpene and 1,8-cineole is a saturated bicyclic terpene ether and both terpenes might be potential biofuel candidates. Focus in this study is the intermediate temperature region between 673 and 1173 K to obtain insights into the first fuel decomposition steps and the formation of typical soot precursors. The obtained mole fraction profiles for over 40 species in each of the investigated terpenes are a first step for future development and validation of chemical kinetic combustion mechanisms. While the overall species pool is similar, significant concentration differences can be observed for certain combustion intermediates. For limonene, larger quantities of C8–C10 hydrocarbons are detected and most of them are probably substituted benzenes or cyclohexadienes formed from hydrogen abstraction. Some reaction steps in the decomposition of limonene may also involve initial isomerization of the fuel molecule. In contrast, direct formation of C7H11 radicals and acetone (C3H6O) is identified as an important decomposition step of 1,8-cineole. C7H11 is then a source of toluene (C7H8) and cyclohexadienes (C6H8). Generally, a higher sooting propensity of limonene compared to 1,8-cineole can be expected due to the higher concentrations of polycyclic aromatic hydrocarbons (PAHs) in the investigated temperature range. During limonene oxidation, formation of oxygenated species larger than the fuel molecule are observed and might represent carbonyls or cyclic ethers from the first oxygen addition due to low-temperature chemistry.

Growth of (Cu,C)Ba2Ca2Cu3O9±δ thin films on flexible Hastelloy tapes

Abstract The applications of superconducting cable or magnet require that the superconductors are made into wires or tapes. For cuprate superconductors, this is a big challenge because of the friability and short coherence length of the materials; weak links are easy to be formed at the grain boundaries hindering the flowing of the supercurrent. One of the ways is to fabricate superconducting films on flexible metallic tapes with oxide buffer layers. The successful one so far is the REBa2Cu3O7 (RE=rare earth elements) films in tape form, as called the coated conductors. While the superconducting transition temperature of REBCO system is limited to around 90 K. Here we report the successful fabrication of another new non-toxic superconducting film, namely (Cu,C)Ba2Ca2Cu3O9±δ on these flexible metallic tapes with LaMnO3 and CeO2 as the top buffer layers. The onset superconducting transition occurs at 112 K and 110 K, and the zero-resistance transition temperatures are about 96 K and 98 K, respectively. The temperature dependent resistivity under magnetic fields in different directions reveals a relatively small anisotropy. Further optimization of the films will improve the zero resistance transition temperature, thus can also improve the characteristic properties for applications. Our results show that the (Cu,C)Ba2Ca2Cu3O9±δ is a promising candidate material for the high power applications in liquid nitrogen temperature region.

Thermally Induced FeII Spin Crossover Hybrid Complex incorporating para‐sulfocinnamic acid

Anion‐Driven Light‐Induced Spin Change (AD‐LISC) enables multifunctional materials to switch magnetic states with light, enhancing potential applications in data storage, sensors, and molecular electronics, by improving spin state control by integrating photoactive anions. In this study, we report the synthesis and characterization of new mononuclear FeII coordination complexes, [Fe(3‐bpp)2](psca)2∙solvent (1∙solvent), which includes para‐sulfocinnamic acid (psca) as a non‐coordinated anion. 57Fe Mössbauer spectroscopy and magnetic susceptibility measurements (SQUID) reveals a mixture of high‐spin and low‐spin states in 1 and 1∙2.5H2O, with a predominance of low‐spin sites at room temperature. The desolvated form 1 shows a gradual spin crossover behaviour centred around the room temperature region. Additionally, single crystal X‐ray diffraction, evaluated according to Schmidt's criteria for [2 + 2] photodimerization, revealed that 1∙X does not satisfy the spatial requirements for photodimerization; accordingly, no colour change was noticed upon UV light exposure.

Global modeling of iodine Hall thruster performance and discharge properties

A 0D model for an iodine-fed Hall thruster is presented. A complete set of reactions is used to account for iodine plasma chemistry phenomena and trace the presence of multiple neutrals and ionized species. The model is developed using novel assumptions based on experimental data trends as derived from the literature. The simulation domain is divided into two zones in order to refine the iodine molecule dissociation process localized in the low electron temperature region found upstream in the channel. After validating a xenon version of the model against SPT-100 characteristics, numerical results are compared against experimental data relative to a low-power iodine-fed Hall thruster. Discharge current and thrust are predicted with satisfactory quantitative agreement, and overall trends are effectively captured. The numerical results indicate a relatively large portion of ionized molecules, while negative ions appear to occur in non-negligible amount upstream in the thruster channel.

Relaxation dynamics of a mixed ferrimagnetic Ising system with random anisotropy

The relaxation dynamics of a mixed spin-1/2 and spin-1 ferrimagnetic Ising system with random anisotropy has been investigated using Onsager’s theory of irreversible thermodynamics. The magnetic Gibbs energy production, arising due to irreversible processes, is computed using the equilibrium mean-field Gibbs energy, based on the variational principle and the Gibbs–Bogoliubov inequality. In the framework of linear response theory, the time derivatives of the sublattice magnetizations are treated as fluxes conjugate to their corresponding generalized forces. Two relaxation times are computed, and their dependence on temperature and crystal field variances is examined near phase transition points for four distinct topologies, each corresponding to different phase diagrams. These phase diagrams emerge from random anisotropy drawn from a bimodal probability distribution: P(Δi)=12δ(Δi-Δ(1+α))+δ(Δi-Δ(1-α)). One of the relaxation times, denoted as τ1, increases rapidly and diverges near the critical and tricritical points separating the ferrimagnetic and paramagnetic phases. For α≥0, critical slowing down, characterized by the divergence of τ1, is observed near the isolated ordered critical points between the ferrimagnetic and disorder-induced ferrimagnetic phases. Finally, the variance of the relaxation times is analyzed across regions of crystal field and temperature, as well as the values of α at which re-entrant phenomena occur, due to the competing interactions in the random system.

Deciphering the Sulfur-Involved Bonding Interactions in Sulfurized Polyacrylonitrile: The Formation Thermodynamics and the Roles in Electrochemical Characteristics.

Sulfurized polyacrylonitrile (SPAN) exhibits a very high cycle stability by overcoming the shuttle effect of conventional Li-S batteries. However, there are still controversies in SPAN about the bonding types of sulfur with the matrix, their critical synthesis temperature regions, and their roles in the electrochemical lithium storage reaction, seriously hindering the economical synthesis of SPAN, the optimization of performances, and the exploration of other SPAN-like alternatives. The key to solving the above problems lies in accurate measurements of the thermodynamic evolution of bonding interactions in the synthesis process as well as in the electrochemical process. In this study, soft and tender X-ray absorption spectroscopy (XAS) is utilized to achieve a fine resolution of specific bonding interactions through the selective excitation of C, N, and S. Sulfur-involved bonding interactions have been elucidated, including the bonding type, critical temperature region, linking site, and their interplays. Furthermore, their contributions to lithium storage and their regulations on electrochemical performances are discussed. This study demonstrates the resolving capability of XAS for organic electrode materials and provides insights for further analyzing the cyclability of SPAN and rationally designing alternatives from the perspective of bonding interactions.

The effect of SiCW on the bonding performance of powder/whisker hybrid phenolic adhesive for joining Al2O3 ceramics at different temperature regions (RT-1400 °C)

The effect of SiCW on the bonding performance of powder/whisker hybrid phenolic adhesive for joining Al2O3 ceramics at different temperature regions (RT-1400 °C)

Geographical patterns of intraspecific genetic diversity reflect the adaptive potential of the coral Pocillopora damicornis species complex.

Marine heatwaves are increasing in intensity and frequency however, responses and survival of reef corals vary geographically. Geographical differences in thermal tolerance may be in part a consequence of intraspecific diversity, where high-diversity localities are more likely to support heat-tolerant alleles that promote survival through thermal stress. Here, we assessed geographical patterns of intraspecific genetic diversity in the ubiquitous coral Pocillopora damicornis species complex using 428 sequences of the Internal Transcribed Spacer 2 (ITS2) region across 44 sites in the Pacific and Indian Oceans. We focused on detecting genetic diversity hotspots, wherein some individuals are likely to possess gene variants that tolerate marine heatwaves. A deep-learning, multi-layer neural-network model showed that geographical location played a major role in intraspecific diversity, with mean sea-surface temperature and oceanic regions being the most influential predictor variables differentiating diversity. The highest estimate of intraspecific variation was recorded in French Polynesia and Southeast Asia. The corals on these reefs are more likely than corals elsewhere to harbor alleles with adaptive potential to survive climate change, so managers should prioritize high-diversity regions when forming conservation goals.

Differential effects of warming on carbon budget, photosynthetic yield and biochemical composition of cold-temperate and Arctic isolates of Laminaria digitata (Phaeophyceae).

Cold-temperate and Arctic hard bottom coastal ecosystems are dominated by kelp forests, which have a high biomass production and provide important ecosystem services, but are subject to change due to ocean warming. However, the photophysiological response to increasing temperature of ecologically relevant species, such as Laminaria digitata, might depend on the local thermal environment where the population has developed. Therefore, the effects of temperature on growth rate, biochemical composition, maximum quantum yield, photosynthetic quotient and carbon budget of young cultured sporophytes of Laminaria digitata from the Arctic at Spitsbergen (SPT; cultured at 4, 10 and 16°C) and from the cold-temperate North Sea island of Helgoland (HLG; cultured at 10, 16 and 22°C) were comparatively analyzed. Temperature significantly affected growth rates of L. digitata from SPT and HLG, with the highest rates occurring at 10°C, but growth did not differ between both isolates neither at 10°C nor at 16°C. Nevertheless, maximum quantum yield and carbon fixation rate were highest at 4°C for the Arctic and at 16°C for the cold-temperate L. digitata. Significantly higher rates of oxygen production and carbon fixation were observed in the cold-temperate relative to the Artic L. digitata at 10 and 16°C, respectively. Neither temperature nor biogeographic region of origin affected the photosynthetic quotient, and release rates of dissolved or particulate organic carbon. Total carbon and mannitol content were significantly higher in the Arctic compared to the cold-temperate L. digitata at 10°C, revealing an increased accumulation of storage compounds in the high latitude L. digitata. We conclude that L. digitata from SPT and HLG differ in their sensitivity to increasing temperatures and that the Arctic population from Spitsbergen is likely to benefit from ocean warming, while the temperate population from Helgoland will be negatively affected by further increases in ambient temperature.

Role of divalent doping at A-sites (A=Ca2+, Sr2+, Ba2+ & Pb2+) on thermoelectric and magnetoresistive properties in La0.67(Bi0.0835Na0.0835) A0.165MnO3

The present work reports on the effect of divalent ion doping (Ca2+, Sr2+, Pb2+ & Ba2+) ions at A-site in the compound with compositional formula La0.67(Bi0.0835Na0.0835)A0.165MnO3 on structural, magnetic, magneto-transport and thermoelectric properties. X-ray diffraction reveals orthorhombic structure for calcium and barium doped with no peak splitting observed at ~ 32o whereas rhombohedral structure for strontium and lead dopants with a peak splitting in the main intensity. Doping with divalent ions at A-site in La0.67(Bi0.0835Na0.0835)A0.165MnO3 manganites has introduced Mn2+ ions, changing the ratio of Mn3+/Mn4+ in octahedral site and this has been confirmed from X-ray photospectroscopy studies. The field emission scanning electron microscope images confirm different grain sizes and morphologies for different doping elements and distinguished variation is noticed for strontium doped manganites with a grain size of 1.08µm. Room temperature ferromagnetic behavior was observed in the samples at room temperature except for calcium doped sample and magnetic behavior has been discussed on the basis of the various interactions between mixed valence manganese ions and Mn3+/Mn4+ ratio. Electrical resistivity (ρ) as a function of temperature (T) without magnetic field indicates the double peak behavior and with the application of external magnetic fields, the double peak disappears, in all the investigated samples. Highest MR% at their respective transition temperatures (TP1) has been obtained for lead doped samples when compared to barium, strontium and calcium samples. Activation energies (EP) estimated decreases initially for calcium and strontium whereas it increases for lead and barium dopants i.e. for further increases in ionic radii. The change of sign from positive to negative in Seebeck coefficient (S) was noticed with increasing ionic radii suggesting the variation in the nature of charge carriers. The electron-electron, electron-magnon, magnon-magnon scattering mechanism contributes to the temperature dependent resistivity and thermopower in the low temperature region while in the paramagnetic insulating region is governed by a small polaron hopping mechanism.

Crystal facet tailoring: a promising pathway toward high-performance Y2/3Cu3Ti4O12 thermosensitive ceramics

Y2/3Cu3Ti4O12 (YCTO) thermosensitive ceramics with high-sensitivity and fast-response characteristics have potential applications in the next generation of smart electronic devices.

Hopping conduction in CuInSe2, CuIn3Se5, and CuGa3Te5: are there two different temperature regions in which variable-range hopping occurs?

ABSTRACT Previous studies on the temperature-dependent electrical conductivity σ(T) of n-CuInSe2, n-CuIn3Se5, and p-CuGa3Te5 reported the observations of two temperature regions in which variable-range hopping (VRH) conduction occurs in each of the samples, but cannot explain their origins. In the present study, the σ(T) data have been critically analysed using a model which includes not only VRH conduction but also nearest-neighbor hopping (NNH) conduction in addition to free-carrier conduction. As a result, the σ(T) curves have been deconvoluted into the contributions from VRH, NNH, and free-carrier conduction to prove that the two temperature regions of VRH are only apparent.

Effect of chiral imbalance on the electrical conductivity of hot and dense quark matter using Green–Kubo method within the 2-flavour gauged NJL model

The electrical conductivity of hot and dense quark matter is calculated using the 2-flavour gauged Nambu–Jona–Lasinio (NJL) model in the presence of a chiral imbalance quantified in terms of a chiral chemical potential (CCP). To this end, the in-medium spectral function corresponding to the vector current correlator is evaluated employing the real time formulation of finite temperature field theory. Taking the long wavelength limit of the spectral function we extract the electrical conductivity using the Green–Kubo relation. The thermal widths of the quarks/antiquarks that appear in the expression of electrical conductivity are calculated by considering the 2→2 scattering in the NJL model. The scattering amplitudes containing the polarization functions of the mesonic modes in the scalar and pseudoscalar channels are also evaluated by considering finite value of CCP. We find that the ratio of electrical conductivity to temperature has significant dependence on CCP especially in the low temperature region.

Research on the Fast Charging Strategy of Power Lithium-Ion Batteries Based on the High Environmental Temperature in Southeast Asia

To address the problem of excessive charging time for electric vehicles (EVs) in the high ambient temperature regions of Southeast Asia, this article proposes a rapid charging strategy based on battery state of charge (SOC) and temperature adjustment. The maximum charging capacity of the cell is exerted within different SOCs and temperature ranges. Taking a power lithium-ion battery (LIB) with a capacity of 120 Ah as the research object, a rapid charging model of the battery module was established. The battery module was cooled by means of a liquid cooling system. The combination of the fast charging strategy and the cooling strategy was employed to comprehensively analyze the restrictions of the fast charging rate imposed by the battery SOC and temperature. The results indicate that when the coolant flow rate was 12 L/min and the inlet coolant temperature was 22 °C, the liquid cooling system possessed the optimal heat exchange capacity and the lowest energy consumption. The maximum temperature (Tmax) of the battery during the charging process was 50.04 °C, and the charging time was 2634 s. To lower the Tmax of the battery during the charging process, a charging rate limit was imposed on the temperature range above 48 °C based on the original fast charging strategy. The Tmax decreased by 0.85 °C when charging with the optimized fast charging strategy.

Systematic analysis of New Technologies and trends of infrared photodetectors

Infrared detection has always been regarded as an important technology with significant applications in military, industrial, and daily life. Infrared photodetectors (IRPDs) have experienced the development process from thermal IRPDs to photonic IRPDs, until now, the latter can be widely used in focal plane array (FPA). For a long time, IRPD technology based on HgCdTe and InSb materials has dominated the market, but there are still limitations in operating temperature and detectable wavelength region. Since the 21st century, people have been committed to researching new types of IRPDs. Type-II superlattice system technology is considered an alternative solution to the long wave region, and its performance can be improved by adding unipolar potential barriers, which only allow one type of carriers to pass normally. Quantum well and quantum dot are new IRPD technologies based on quantum theory. The former is based on developed GaAs growth technology and can reduce production costs; The latter utilizes the binding mechanism of quantum dots to increase the operating temperature, but whether it can be applied to large-scale devices remains to be researched. All these technologies will contribute to the development and application of the third generation of IRPD.

Surface Microstructure Enhanced Cryogenic Infrared Light Emitting Diodes for Semiconductor Broadband Upconversion.

Broadband upconversion has various applications in solar photovoltaic, infrared and terahertz detection imaging, and biomedicine. The low efficiency of the light-emitting diodes (LEDs) limits the broadband upconversion performance. In this paper, we propose to use surface microstructures to enhance the electroluminescence efficiency (ELE) of LEDs. Systematical investigations on the cryogenic-temperature performances of microstructure-coupled LEDs, including electroluminescence efficiency, luminescence spectrum, and recombination rate, have been carried out by elaborating their enhancement mechanism and light emitting characteristics both experimentally and theoretically. We have revealed that the reason for the nearly 35% ELE enhancement of the optimized structure under cryogenic temperature and weak injection current is the efficient carrier injection efficiency and the high recombination rate in the active region. We also compare studies of the surface luminescence uniformity of the optimized LED with that of the unoptimized device. This work gives a precise description, and explanation of the performance of the optimized microstructure coupled LED at low temperatures, providing important guidance and inspiration for the optimization of broadband upconverter in the cryogenic temperature region.

Hydration behavior of asparagine: an approach using time domain reflectometry at low temperatures

The dielectric behavior of Asparagine (C4H8N2O3) in water over the frequency range of 10 MHz to 30 GHz in the temperature region of 278.15–303.15 K in a step of 5 K has been carried out using time domain reflectometry (TDR) at various concentrations of asparagine. The obtained dielectric spectra reveal two relaxation peaks. The low frequency relaxation is attributed to the interaction between solute-solute molecules, while the high frequency relaxation is due to the reorientation of solvent molecules. The various dielectric and thermodynamic parameters were calculated such as the dielectric constant (εj), relaxation time (τj), effective dipole moment (μeff), Kirkwood correlation factor (g1), hydration number or the number of solvent molecules effectively bounded to solute molecule (Zib), effective volume of rotation (Veff), free energy of activation (ΔFj), entropy of activation (ΔSj) and enthalpy of activation (ΔHj). The static dielectric constant (ε1) shows increasing trend towards the higher concentration of asparagine, where as the high frequency dielectric constant (ε2) decreases with the concentration of asparagine. The relaxation time of low frequency (τ1) and high frequency (τ2) processes increases towards higher concentration of solute molecule and also towards lower temperature. As the concentration of asparagine increases, the value of effective dipole moment (μeff) decreases. With increasing amino acid concentrations hydration dynamics get affected and indicated by decreasing the hydration number (Zib) but the hydration dynamics of aqueous asparagine was found least temperature dependent.

Role of doping level, electric field and temperature on the charge transport properties of electrochemically polymerized poly(3-butylthiophene) and poly(3-hexylthiophene) devices

Abstract In this article, the charge transport properties of electrochemically polymerized poly(3-butylthiophene) (P3BT) and poly(3-hexylthiophene) (P3HT) devices using a sandwiched metal/polymer/metal structure are explored. These devices are successfully fabricated at different doping levels using electrochemical polymerization and thermal evaporation techniques. Low temperature-dependent Current-Voltage (I-V) measurement reveals that space charge limited conduction (SCLC) mechanism with a field and temperature-dependent mobility in the form of the Poole-Frenkel model governs the transport mechanism. The zero-field dependent mobility exhibits a thermally activated behavior, with two activation processes observed- one at higher and another at lower temperatures. The activation energy increases with the decrease in doping level at higher temperature regions, indicating the significant role of doping level in the activation process. However, electric field plays a significant role in the transport mechanism at lower temperatures. Comparatively, P3HT devices exhibit lower conductivity and mobility values than P3BT devices. The mobility ratio μ(0,300K)/μ(0,50K) for P3HT devices is considerably larger than that for P3BT devices. Additionally, the activation energy of P3HT devices is higher, providing evidence of a higher relative energetic disorder than P3BT devices.

Changing Geography of Hop Regions in the World 1990–2022

Has the territorial concentration of hop production in the world increased? Has there been an increase in hop production in cooler temperature and higher rainfall hop regions as would be expected due to global warming? How has hop production developed in countries with different levels of the hop industry? These are some of the questions that the article tries to answer. The article is mainly based on data from BarthHass reports from 1990 to 2022. The analysis shows that the United States and German hop regions were responsible for the significant increase in the territorial concentration of production in the world, while in many countries with a tradition of growing hops, production weakened or even ended. Despite global warming, production has increased mainly in hop regions with somewhat higher temperatures and low rainfall. For the development of hop farming in individual countries and hop regions, the maturity of their hop industry is important. It is mainly about the level of breeding and cultivation of hops and the level of hop research.

Polarization-induced two-dimensional hole gases in N-polar AlGaN/GaN heterostructures

We report the observation of two-dimensional hole gases (2DHGs) in N-polar AlGaN/GaN heterostructures grown on single-crystal GaN substrates by plasma-assisted molecular beam epitaxy. A systematic study varying AlGaN barrier thickness is performed. The presence of 2DHGs is confirmed by persistent p-type conductivity and high hole mobility observed in temperature-dependent Hall-effect measurements down to 10 K, and the dependence of 2DHG density on the AlGaN barrier thickness indicates its polarization induced origin. 2DHG with a sheet density of 7.5×1012 cm−2 shows a relatively high hole mobility of 273 cm2 V−1 s−1 at 10 K. Mobility model fit suggests that acoustic phonon scattering is the dominant scattering mechanism in the sub-room temperature region. This work indicates that the quality of N-polar 2DHGs is comparable to that of state-of-the-art metal-polar 2DHGs, contributing to a building block for potential high-quality N-polar p-channel devices.