Positive Temperature Research Articles

Investigations into penetration depth profiles of hydrogenic species in beryllium plasma-facing components via molecular dynamics simulations

During the operation of nuclear fusion reactors, plasma-facing components lining the reactor vessel are continually bombarded by plasma species. The penetration and subsequent trapping of these bombarding plasma ions has implications for component damage as well as in-vessel inventory. Accurately predicting the expected ion penetration depth profiles at a range of plasma ion and surface temperatures typical of fusion reactor operating conditions will inform the scrape-off layer design to limit particle radiation damage and tritium trapping in order to prolong the lifetime of the plasma-facing components and satisfy the DT fuel cycle requirements. By defining a statistical distribution for ion penetration depth and describing the evolution of its parameters across the fusion parameter space of interest, the expected ion deposition depth profiles can be calculated for any subset of ion and surface temperature ranges as needed. Molecular dynamics simulations were used to study the bombardment of beryllium lattices with surface temperatures of up to 1100 K by 5 eV–150 eV deuterium and tritium ions, and the resulting ion penetration depths were investigated. The distributions of two penetration depth quantities, considered from the perspectives of lattice damage and hydrogen retention are defined and their distribution parameter dependence on surface and ion temperature is identified. The expected positive correlation between penetration depth and ion temperature is observed, where the non-linear relationship between these quantities indicates the expected form of the velocity dependence of nuclear stopping power at low bombardment energies. Isotope effects on the distributions are also investigated, with results suggesting that heavier ions have comparably lower mobility within the sample and will generally accumulate closer to the surface. A short study on ion deposition rates is also performed; a non-linear increase of deposition rate with increasing bombarding ion energy has been observed, and evidence of a weak positive surface temperature correlation has been noted.

Thickness-Dependent Electrical Characteristics of Sputtered BFO Thin Films over Wide Temperature Range

This study explores how thickness and grain size impact leakage current in RF-sputtered BFO thin films. Morphology reveals that increasing film thickness leads to larger grains, boosting grain resistivity by altering oxygen vacancies, thus reducing leakage current. Pt/Ti/BFO/FTO capacitive heterostructures are examined at varied temperatures, demonstrating a positive temperature coefficient of resistance effect. This effect stems from the closely linked interaction between multiferroic BFO and highly conductive oxide FTO, and potentially forming an electrical double layer at the Pt/Ti/BFO interface. Additionally, a dominant modified Space Charge Limited Current conduction mechanism is observed in Pt/Ti/BFO/FTO capacitive heterostructures under varying electric fields.

Continuous Growth of Crystalline InGaZnO on InLaO by Spray Pyrolysis for High‐Performance Thin‐Film Transistors with Excellent Stability

AbstractInGaZnO (IGZO) based thin film transistors (TFTs) are successfully employed in commercial displays due to their excellent electrical properties but next‐generation displaybackplanes demand higher mobility. A heterojunction structure crystalline oxides can offer superior mobility and stability. Herein, the continuous growth of IGZO is reported on the crystalline InLaO (ILO) layer by spray pyrolysis, which closely resembles the crystalline structure of grown ILO layer. The crystalline structure of the IGZO is confirmed by grazing incidence X‐ray diffraction and high‐resolution transmission electron microscopy. The bilayer IGZO/ILO TFT exhibits remarkable electrical performance, including a high saturation mobility of 55.0 cm2 V−1 s−1, low subthreshold swing of 110 mV dec−1, and high ION/OFF ratio of ≈109 with excellent stability under positive bias temperature stress with In addition, the inverter and ring oscillator based on the IGZO/ILO TFTs demonstrate a high voltage gain of 120 and a low propagation delay of 16.8 ns, respectively. The remarkable performance of bilayer IGZO/ILO TFT by spray pyrolysis is attributed to the In2O3‐like crystalline IGZO grown on ILO film. This leads to reduced lattice mismatch, resulting in minimizing grain boundaries and defects that can hinder electron transport at the interface. The matched crystal structure leads to efficient charge transport at the IGZO and ILO heterojunction, resulting in remarkable TFT performance.

PH regulates the formation of organosulfates and inorganic sulfate from organic peroxide reaction with dissolved SO2 in aquatic media

Abstract. Organic peroxides (OPs) are an important component of dissolved organic matter (DOM), detected in various aquatic media. Despite their unique functions as redox agents in water ecosystems, the complete mechanisms and factors controlling their transformation are not explicitly established. Here, we evaluate the pH effect on the aqueous-phase reaction of three selected OPs (methyl hydroperoxide (MHP), peracetic acid (PAA), and benzoyl peroxide (BZP)) with dissolved SO2. Results show that due to the presence of the hydroperoxyl group in their structures, MHP and PAA are susceptible to forming inorganic sulfate and organosulfate (methyl sulfate for MHP and acetyl sulfate for PAA) depending on the pH, while BZP exclusively forms organosulfate (benzoyl sulfate) in the pH range investigated. Moreover, it is seen that the ability of PAA to form inorganic sulfate relative to organosulfate is more pronounced, which is supported by a previous experimental observation. The effective rate constants of the transformation of these peroxides within the pH 1–10 and 240–340 K ranges exhibit positive pH and temperature dependencies, and BZP is seen to degrade more effectively than MHP and PAA. In addition to the pH impact, it is highlighted that the formation of organic and/or inorganic sulfate strongly depends on the nature of the substituents on the peroxy function. Namely, PAA and BZP are more reactive than MHP, which may be attributed to the electron-withdrawing effects of -C(O)R (R = -CH3 and -C6H5 for PAA and BZP, respectively) substituents that activate the peroxy function. The results further indicate that the aqueous-phase degradation of OPs can adequately drive the change in the chemical composition of DOM, both in terms of organic and inorganic sulfate mass fractions.

What caused large ozone variabilities in three megacity clusters in eastern China during 2015–2020?

Abstract. Due to a robust emission control policy, significant reductions in major air pollutants, such as PM2.5, SO2, NO2, and CO, were observed in China between 2015 and 2020. On the other hand, during the same period, there was a notable increase in ozone (O3) concentrations, making it a prominent air pollutant in eastern China. The annual mean concentration of maximum daily 8 h average (MDA8) O3 exhibited alarming linear increases of 2.4, 1.1, and 2.0 ppb yr−1 (ppb is for parts per billion) in three megacity clusters: Beijing–Tianjin–Hebei (BTH), the Yangtze River Delta (YRD), and the Pearl River Delta (PRD), respectively. Meanwhile, there was a significant 3-fold increase in the number of O3-exceeding days, defined as MDA8 O3 > 75 ppb. Our analysis indicated that the upward increases in the annual mean concentration of MDA8 were primarily driven by the rise in consecutive O3-exceeding days. There were expansions of high O3 in urban centers to rural areas accompanied by a saturation effect so that MDA8 O3 concentrations at the high-O3 stations in 2015 remained nearly constant at 100 ppb. Last, we found a close association between O3 episodes with 4 or more consecutive O3-exceeding days and the position and strength of tropical cyclones (TCs) in the northwest Pacific and the West Pacific subtropical high (WPSH). The TC and WPSH contributed to meteorological conditions characterized by clear skies, subsiding air motion, high vertical stability in the lower troposphere, increased solar radiation, and a positive temperature anomaly at the surface. These favorable meteorological conditions greatly facilitated the formation of O3. Thus, we propose that the worsening O3 increases observed in the BTH, YRD, and PRD regions from 2015 to 2020 can be mostly attributed to enhanced photochemical O3 production resulting from an increased occurrence of meteorological conditions with high solar radiation and positive temperature anomalies under the influence of the WPSH and TCs.

Percolation behavior and sensing performance of polypropylene‐based conductive polymer composites under compressive strains and temperature

AbstractPercolation behavior is highly significant for mechanical, thermal, and electrical properties, as well as manufacturing processes of conductive polymer composites (CPCs). It has been reported that temperature and external loads are important parameters directly affecting the percolation threshold. Herein, carbon black/polypropylene (CB/PP) and carbon black/multiwalled carbon nanotubes/polypropylene (CB/MWCNTs/PP) composites are prepared via the melt blending method. After the synthesis of composites, the rheological properties, the filler distribution, crystallization, and conductive network formation within the composite are evaluated. The effect of conductive network structure on conductive percolation behavior is studied under various compressive strains and temperatures. Finally, the sensing performance under compressive strain and temperature cycling is discussed. Obtained results reveal that MWCNTs work as “bridges” between segregated CB particles leading to a synergic effect on the conducting properties. The volume resistivity of PP‐based CPCs exhibits a critical strain and a positive temperature coefficient (PTC), resulting in altered percolation. PP‐based CPCs with the addition of MWCNTs have greater PTC intensity, demonstrating sensing stability and sensitivity to compressive strain under temperature cycling. This study underscores the essential contribution of MWCNTs in building conductive networks and elucidates the potential application of PP‐based CPCs with superior sensing performance under compressive strain and varying temperatures.

Effect of Weather Parameters on Population Dynamics of Bihar Hairy Caterpillar [Spilarctia (Spilosoma) obliqua Walker] in Mungbean [Vigna radiata (L.) Wilczek

The present investigation revealed that Bihar hairy caterpillar was first recorded during 32nd standard week (1.92 larvae/plant) which reached to its maximum during 41st standard week (11.93 larvae/plant) and there after gradually decreased up to 1.33 larvae/plant during 44th standard week.
 The maximum temperature showed non-significant positive correlation, minimum temperature and relative humidity showed non-significant negative correlation while rain fall showed significant negative correlation with the population buildup of Bihar hairy caterpillar.

Multidecadal Changes in the Flow Velocity and Mass Balance of the Hailuogou Glacier in Mount Gongga, Southeastern Tibetan Plateau

Maritime glaciers in the southeastern Tibetan Plateau (TP) have experienced important changes in mass and dynamics over the past decades, challenging the regional water supply and glacier-related hazards. However, knowledge about long-term variations in the surface velocity and mass balance of maritime glaciers remains incomplete due to the lack of representative observations in the southeastern TP. In this study, offset tracking is employed to measure spatiotemporal variation in the surface velocity of the Hailuogou Glacier (HLG) in Mount Gongga of the southeastern TP using Sentinel-1A imagery, while the time series of the HLG mass balance is reconstructed since 1950 by a physically based energy–mass balance model. Our satellite-based results find that HLG surface velocity shows significant spatial heterogeneity with a double-peak pattern along the flow line, and sustained slowdown below the icefall zone has been observed during the past nearly 40 years, although the icefall zone and the area above it have become relatively active. Our modeling indicates a persistent increase in mass loss over the last seven decades with an average rate of −0.58 m water equivalent (w.e.) year−1, which has accelerated in the past two decades. Sustained slowdown on the glacier is concomitant with pronounced negative mass balance, thereby enhancing glacier wastage in recent decades. The long-term trend in HLG mass loss is mainly driven by an increase in positive air temperature that decreases surface albedo and solid precipitation ratio and increases longwave incoming radiation, besides the influence of supraglacial debris cover. Large-scale atmospheric circulation patterns in the Eurasian region provide important implications for regional-to-local climate variability, unsustainably intensifying the trend of the negative mass balance of the HLG in the southeastern TP in the past two decades.

Origins of Underestimated Indian Ocean Dipole Skewness in CMIP5/6 Models

Abstract The Indian Ocean dipole (IOD) is the dominant mode of interannual variability in the tropical Indian Ocean (TIO), characterized by warming (cooling) in western TIO and cooling (warming) in eastern TIO during its positive (negative) phase. Observed IOD events exhibit distinct amplitude asymmetry in relation to negative nonlinear dynamic heating. Nearly all models in phase 5 of the Coupled Model Intercomparison Project (CMIP) simulate a less-skewed IOD than observed, but 6 out of 20 CMIP6 models can reproduce realistic high skewness. Analysis of less-skewed models indicates that the positive IOD-like biases in the mean state, which can be traced back to their weaker simulations of the preceding Indian summer monsoon, reduce the convective response to positive sea surface temperature anomalies in the western TIO, resulting in a weaker zonal wind response and weaker nonlinear zonal advection during positive IOD events. Besides, ocean stratification in the eastern TIO influences the IOD skewness: stronger stratification leads to larger mixed-layer temperature response to thermocline changes, contributing to larger anomalous vertical temperature gradient, larger nonlinear vertical advection, and thus stronger positive IOD skewness. Our findings underscore the importance of reducing Indian summer monsoon biases and eastern TIO stratification biases, for properly representing the IOD in Earth system models.

Numerical simulation of temperature gradient effects on gallium nitride crystal growth by sodium-flux method

During the growth of gallium nitride single crystals by sodium-flux method, temperature significantly impacts crystal quality. In this study, the mechanism of the effect of different temperature gradients on crystal growth is analyzed in depth using a combination of numerical simulation and experiment. The experimental results show that epitaxial growth of crystals occurs under positive temperature gradient conditions, while there is dissolution of seed crystals under negative temperature gradient conditions. The temperature, flow, and concentration data of the melted material during crystal growth were calculated using numerical simulation. The simulation findings reveal that the distribution of solution supersaturation varies according to temperature. High supersaturation at the bottom of the melt is favorable for crystal epitaxial growth on the surface of seed crystals under a positive temperature gradient. Meanwhile, low supersaturation at the top of the melt suppresses the hard polycrystalline layer here. Under negative temperature gradient conditions, low supersaturation at the bottom of the melt may lead to remelting of seed crystals, which is consistent with the experimental phenomenon. Furthermore, we propose an optimized heat source profile. This profile manages high supersaturation near seed crystals, aiding continuous growth. Finally, we have applied the curve in an applied way by proposing a multi-stage heating device, based on which the desired arbitrary temperature profile can be modulated. This research has broad applications in a variety of crystal growth experiments using fluid as the mother phase.

The Extraordinary March 2022 East Antarctica “Heat” Wave. Part II: Impacts on the Antarctic Ice Sheet

Abstract Between 15 and 19 March 2022, East Antarctica experienced an exceptional heat wave with widespread 30°–40°C temperature anomalies across the ice sheet. In Part I, we assessed the meteorological drivers that generated an intense atmospheric river (AR) that caused these record-shattering temperature anomalies. Here, we continue our large collaborative study by analyzing the widespread and diverse impacts driven by the AR landfall. These impacts included widespread rain and surface melt that was recorded along coastal areas, but this was outweighed by widespread high snowfall accumulations resulting in a largely positive surface mass balance contribution to the East Antarctic region. An analysis of the surface energy budget indicated that widespread downward longwave radiation anomalies caused by large cloud-liquid water contents along with some scattered solar radiation produced intense surface warming. Isotope measurements of the moisture were highly elevated, likely imprinting a strong signal for past climate reconstructions. The AR event attenuated cosmic ray measurements at Concordia, something previously never observed. Last, an extratropical cyclone west of the AR landfall likely triggered the final collapse of the critically unstable Conger Ice Shelf while further reducing an already record low sea ice extent. Significance Statement Using our diverse collective expertise, we explored the impacts from the March 2022 heat wave and atmospheric river across East Antarctica. One key takeaway is that the Antarctic cryosphere is highly sensitive to meteorological extremes originating from the midlatitudes and subtropics. Despite the large positive temperature anomalies driven from strong downward longwave radiation, this event led to huge amounts of snowfall across the Antarctic interior desert. The isotopes in this snow of warm airmass origin will likely be detectable in future ice cores and potentially distort past climate reconstructions. Even measurements of space activity were affected. Also, the swells generated from this storm helped to trigger the final collapse of an already critically unstable Conger Ice Shelf while further degrading sea ice coverage.

Dynamics of the Barrier Layer Dipole in the Equatorial Indian Ocean

AbstractThe barrier layer (BL) significantly impacts the upper ocean circulation and thermodynamic structure by inhibiting the heat and momentum exchange between the mixed layer (ML) and the subsurface layer. There exist sea surface temperature and salinity dipole modes in the tropical Indian Ocean, however, a BL dipole mode has not yet been identified. Using the latest observations and ocean reanalysis, here we show a robust BL dipole mode in the central and eastern equatorial Indian Ocean, which is highly correlated with the Indian Ocean Dipole (IOD) events. Composite analysis shows that the BL thickness anomalies peak in autumn and are much larger during positive IOD events than during negative IOD events. We show that a positive BL dipole phase is characterized by positive BL thickness anomalies in the central equatorial Indian Ocean and negative BL thickness anomalies in the eastern equatorial Indian Ocean, and vice versa for a negative BL dipole phase. During positive IOD events, negative surface salinity anomalies slightly affect the ML depth along the equatorial Indian Ocean. Positive subsurface temperature anomalies deepen the isothermal layer (IL) in the central equatorial Indian Ocean and strong negative subsurface temperature anomalies significantly lift the IL in the eastern equatorial Indian Ocean, controlling the BL thickness anomalies and forming a positive BL dipole pattern. This operates in an opposite direction during negative IOD events. Our study shows a close relationship between the BL dipole and the IOD and has far‐reaching implications for better understanding and predicting the IOD events.

Hot-Carrier Damage in N-Channel EDMOS Used in Single Photon Avalanche Diode Cell through Quasi-Static Modeling.

A single photon avalanche diode (SPAD) cell using N-channel extended-drain metal oxide semiconductor (N-EDMOS) is tested for its hot-carrier damage (HCD) resistance. The stressing gate-voltage (VGS) dependence is compared to hot-hole (HH) injection, positive bias temperature (PBT) instability and off-mode (VGS = 0). The goal was to check an accurate device lifetime extraction using accelerated DC to AC stressing by applying the quasi-static (QS) lifetime technique. N-EDMOS device is devoted to 3D bonding with CMOS imagers obtained by an optimized process with an effective gate-length Leff = 0.25 µm and a SiO2 gate-oxide thickness Tox = 5 nm. The operating frequency is 10 MHz at maximum supply voltage VDDmax = 5.5 V. TCAD simulations are used to determine the real voltage and timing configurations for the device in a mixed structure of the SPAD cell. AC device lifetime is obtained using worst-case DC accelerating degradation, which is transferred by QS technique to the AC waveforms applied to N-EDMOS device. This allows us to accurately obtain the AC device lifetime as a function of the delay and load for a fixed pulse shape. It shows the predominance of the high energy hot-carriers involved in the first substrate current peak during transients.

Evaluating Hydrogen-based Moderators in High-Temperature Gas-cooled Reactors with 5 wt% Enriched Uranium Annular Fuel Rods

Abstract Small Modular Reactors (SMRs) based on high temperature gas-cooled reactor (HTGR) technology are being developed for providing high-temperature process heat and high-efficiency (>40%) electrical power generation. However, most of the HTGR-SMR concepts require high assay low enriched uranium (HALEU) fuel, with enrichments typically above 10 wt% 235U/U, to get sufficiently high burnup levels and fuel lifetime. The need for HALEU is primarily a consequence of the low volumetric density of fissionable material in tri-structural isotropic (TRISO) fuel particles, and also the use of graphite as a moderator/reflector. A previous study has shown that a modified prismatic HTGR fuel assembly with hydrogen-based moderator (7LiH) and cylindrical fuel elements of 5 wt% 235U/U enriched uranium can greatly reduce fuel consumption of a HTGR. However, such a design concept could lead to positive temperature reactivity coefficients (TRCs), making reactor control more challenging, with reduced passive safety. The purpose of this study is to evaluate variations of the hydrogen-based moderator in this alternative fuel assembly concept to identify configurations that achieve negative TRCs, thus improving passive safety characteristics. Calculation results demonstrate that negative TRCs can be achieved with reduced hydrogen mass such that natural uranium consumption is substantially less than that of the TRISO fuel concept, with comparable or higher core life. This study also explores the option of using 7LiOH and NaOH as hydrogen-based moderators, instead of 7LiH, thus allowing operation at higher temperatures, where hydrogen TRCs are lower.

A CMIP6 Analysis of Past and Future Arctic Winter Stratospheric Temperature Trends

AbstractReanalysis data reveal a weak warming trend in the midwinter Arctic stratosphere, contrary to the cooling expectation based on the greenhouse gas effect. This trend is also influenced by the occurrence of sudden stratospheric warmings (SSWs). Using Phase 6 of the Coupled Model Intercomparison Project (CMIP6) we investigate temperature trends over a similar timescale as ERA5 and find that CMIP6 models can replicate the positive midwinter temperature trend in the mid‐lower stratosphere. However, when considering the multi‐model mean, this positive temperature trend is much weaker than ERA5. Extrapolating to the future, we find that the SSW‐driven positive temperature trend will likely not continue in the future based on the SSP2‐4.5 and SSP5‐8.5 climate scenarios. Instead, the models project there will be widespread cooling throughout the Arctic winter stratosphere regardless of the occurrence of SSWs. Using a subsample of CMIP6 models which replicate the seasonality of the Arctic winter stratosphere most similarly to that of ERA5, we also find that the zonal wind strength during SSWs correlates the most with the temperature trends found there. However, trends in the zonal wind strength alone cannot account for the observed temperature trends among the CMIP6 models.

Shear strength model of unsaturated frozen soil based on soil freezing characteristic and soil water characteristic

The strength characteristics of unsaturated soil after freezing significantly influence the safety of engineering construction in frozen soil regions. In this study, the soil freezing characteristic curve (SFCC) and soil water characteristic curve (SWCC) of unsaturated lean clay were tested. Based on the similarity between SFCC and SWCC, the unfrozen water content of SFCC was used to replace the water content of the SWCC to obtain the expression for soil suction under different negative temperatures. A shear strength model of unsaturated frozen soil was established. According to unsaturated triaxial tests under different conditions, the effectiveness of the established unsaturated soil shear strength model was verified. The test results show that in the rapid freezing stage of the SFCC, the volumetric unfrozen water content with an initial matrix suction of 57 kPa exhibited the largest rate of change. The stress-strain curve of soil at positive temperature is strain hardening type, and that at negative temperature presents different types under the influence of temperature, initial matrix suction and confining pressure. The effective cohesion and internal friction angle of soil varied significantly under the influence of temperature and initial matrix suction. When the initial matrix suction was constant, the unsaturated shear strength of the soil increased nonlinearly with a decrease in temperature. When the temperature was ≥−5 °C, the shear strength increased with an increase in initial matrix suction, but decreased when the temperature was ≤−5 °C. The model fitting results were consistent with the measured results of the unsaturated triaxial test, which verifies the validity of the model. This research can provide a reference for studying the mechanical characteristics of unsaturated frozen soil under negative temperature.

Solubility determination and thermodynamic model analysis of L-α-glyceryl phosphorylcholine in different organic solvents of 278.15 K to 323.15 K

L-α-glyceryl phosphorylcholine, also referred to as choline ethanol phosphate and phosphocholine glycerophosphate, is a naturally occurring metabolite of water-soluble phospholipids in animals. This molecular property is important for informing the crystallization and purification of drugs. The solubility of L-α-glyceryl phosphorylcholine was determined in ten pure solvents and three mixed solvents under atmospheric pressure. The experimental results indicate that L-α-glyceryl phosphorylcholine is most soluble in methanol and least soluble in acetone. Additionally, the solubility of L-α-glyceryl phosphorylcholine was found to increase with temperature within the experimental range. Furthermore, the solubility of L-α-glyceryl phosphorylcholine in binary solvents is dependent on the proportion of positive solvent and temperature. The solubility of L-α-glyceryl phosphorylcholine increases with the proportion of positive solvent. XRD and DSC results indicate that the crystal form of L-α-glyceryl phosphorylcholine remains unchanged before and after dissolution in the reagent, and its melting point temperature is 413.15 K. Various models, including the modified Apelblat model, λh model, Jouyban-Acree model, SUN model, and CNIBS/R-K model, were used to fit the solubility data of L-α-glyceryl phosphorylcholine in different solvents. The study found that the modified Apelblat model and CNIBS/R-K model were the most appropriate for fitting the data. The KAT-LSER model was used to analyze the molecular interactions between solvents and solutes, revealing that the solvent step method with non-specific polarity/polarization interaction had the greatest impact on solubility.

Computational investigation of HO•-induced atmospheric transformation and ecological risk assessment of 2-methyl-4-chlorophenoxyacetic acid

2-Methyl-4-chlorophenoxyacetic acid (MCPA) is a pervasive phenoxyacetic acid herbicide, frequently identified in environmental matrices. This study undertakes a systematic investigation of the atmospheric environmental transformation behavior and potential ecological risks of hydroxyl radical (HO•) induced MCPA for the first time, employing computational chemistry and computational toxicology methodologies. Our findings indicate that the initial degradation of MCPA can be triggered by both HO•-addition and hydrogen-abstraction reactions, with the latter being more likely to occur. The primary reaction pathways were identified as R2, R3, R8, and R13. The total rate constant for the gas-phase reaction of MCPA with HO• was calculated as 8.59 × 10−12 cm3 molecule −1 s−1 at 298 K. This total rate constant displayed a distinct positive temperature dependence within the temperature range of 250–375 K. Structures of 25 transformation products, which include 7 experimentally observed compounds, were determined from further reactions of crucial intermediates. The toxicity assessment of MCPA and its transformation products indicated that most of the hydroxyl oxidation products exhibit toxicity to aquatic organisms and possess mutagenic, developmental toxic, non-genotoxic carcinogenic, and skin irritating or corrosive properties. This research contributes to a comprehensive understanding of the transformation mechanisms, kinetics, and environmental repercussions of gas-phase MCPA, enhancing our ability to predict and mitigate its ecological impact.

Investigation of structural, temperature and frequency dependent dielectric behavior of Zn2SnO4@amorphous SiO2 core shell nanocomposites

Herein, the detailed investigation of frequency and temperature dependent dielectric behavior of Zn2SnO4@SiO2 core shell nanocomposites (CSNs) is reported. Powder XRD analysis and FTIR spectral analysis were employed to comprehend the structure. The chemical and valence states are analyzed using XPS which confirms the existence of Zn, Sn, and SiO2, each with their distinctive Zn 2p, Sn 3d, and Si 2p valence states. The core shell formation is confirmed from their distinct color contrast in the TEM micrographs. The electrical response was investigated using impedance spectroscopy in the frequency range 1Hz-1 MHz at various temperatures. Positive temperature coefficient of resistance type behavior was established from impedance and modulus formalism. The total conductivity values were well fitted by the universal Jonscher law σtotal = σdc+ Aωn, and the temperature dependence of dc conductivity was discussed.

Performance Research on Heating Performance of Battery Thermal Management Coupled with the Vapor Injection Heat Pump Air Conditioning

Compared to the use of positive temperature coefficient (PTC) materials that consume electrical energy for low-temperature heating, heat pump air conditioners can provide more energy-efficient heating performance by absorbing and utilizing heat from the outdoor air to heat the cab in order to improve the range of electric vehicles. In addition, in order to make the battery work under safe working conditions, this paper proposes battery thermal management coupled with vapor injection heat pump air conditioning. The system is modeled and analyzed through simulation, and the impact of the compressor speed and ambient temperature changes in the battery cooling performance of the system. The results show that under different compressor RPM (Revolution Per Minute) with an ambient temperature of 5 °C, the average temperature of the battery pack remains below 30 °C, and the majority of individual cell temperatures are maintained within the range of 20 to 35 °C. At a constant compressor RPM of 4000/min under varying ambient temperatures, the average temperature of the battery pack remains below 30 °C, with the majority of individual cell temperatures staying within the range of 20 to 35 °C. And the battery cooling performance still performs well. In the low temperature of −10 °C and −20 °C, the system can still maintain a relatively stable heating capacity compared with the 2009.1W, provided by the environment temperature of 5 °C at the same RPM.