Increase In Temperature Research Articles

Molecular dynamics study on the influence of thermal aging on the mechanical properties of epoxy resins for high voltage bushing.

Thermal aging significantly deteriorates the mechanical properties and service performance of epoxy resins used for the high-voltage bushing. Current studies on the thermal aging behavior of epoxy resins mainly focus on experimental observations. However, an in-depth understanding of the mechanism of thermal aging of epoxy resins requires the monitoring of structural evolution of epoxy resins during thermal aging at the molecular level. To thoroughly analyze the intrinsic factors affecting structural evolution and the effect of thermal aging on the mechanical properties of epoxy resin for high-voltage bushing, epoxy resin models with different crosslinking degrees were established and thermal aging treatments at various temperatures and time periods were carried out by molecular dynamics simulation. It was found that the tensile strength of the epoxy resin was enhanced with the increase of the crosslinking degree, which was related to the elevation of the proportion of C-N and O-H bonds in its structure. With the increase of thermal aging temperature, the tensile strength of the epoxy resin decreased, which was related to the formation of weak bonds. At the early stage of thermal aging and after a period of high-temperature thermal aging, the strength of epoxy resin significantly decreases. The thermal aging of the epoxy resin is accelerated under external loading. In addition, the crosslinking degree and curing agent also affect the thermal aging resistance of epoxy resins. The results of this study can provide guidance for predicting and improving the thermal aging resistance of epoxy resins. Materials Studio was used to construct molecular models and complete crosslinking reactions. DGEBA and 44DDS (or 33DDS) were mixed at a ratio of 2:1, followed by crosslinking reaction. During this process, the Nose method was used to control temperature, the Berendsen method was used to control pressure, and the polymer consistent force field (PCFF) was used to control the motion and force of atoms. Isobaric-isothermal ensemble (NPT ensemble) was used to heat up epoxy resin models to various thermal aging temperatures of 400K, 500K, 600K and 700K. The models were maintained at these temperatures for different thermal aging times of 100ps, 200ps, 300ps, 400ps, 500ps, 600ps, 700ps and 800ps. Afterwards, the models were cooled down to 300K and subjected to uniaxial tensile testing at this temperature with a strain rate of 1 × 109s-1. The structural configurations and stress-strain data during the tensile process were recorded. The flow stress of the material was derived by counting the average stress in the 20-50% strain interval.

Seeded Growth of Size-Tunable Au@Ag Core-Shell Nano-Octahedra and Their Yolk-Shell Derivatives for Near Infrared Photothermal Conversion.

Gold-based nanostructures with well-defined morphologies and hollow interiors have significant potential as a versatile platform for various plasmonic applications including biomedical diagnostics and sensing. In this study, we report the synthesis of Au@Ag core-shell nanocrystals with perfect octahedral shapes and tunable edge lengths via seeded growth. These nanocrystals were then oxidatively carved into yolk-shell nanocages with a retained octahedral morphology. The increase in octahedral edge length and volume of the interior hollow cavity synergistically leads to a red-shift of the LSPR peak. As a result, the optimized Au@AuAg yolk-shell octahedral nanocages showed a remarkable temperature increase of 23 °C upon 15 min irradiation of an 808 nm laser at a power density of 1 W cm-2. This study provides a feasible strategy for creating octahedral AuAg nanostructures with tunable sizes and hollow interiors and validates their promising use in NIR photothermal conversion.

MR Safety of Inductively Coupled and Conventional Intraoral Coils.

Intraoral coils (IOCs) in magnetic resonance imaging (MRI) significantly improve the signal-to-noise ratio compared with conventional extraoral coils. To assess the safety of IOCs, we propose a 2-step procedure to evaluate radiofrequency-induced heating of IOCs and compare maximum temperature increases in 3 different types of IOCs. The 2-step safety assessment consists of electric field measurements and simulations to identify local hotspots followed by temperature measurements during MRI. With this method, 3 different coil types (inductively coupled IFC, transmit/receive tLoop, and receive-only tLoopRx) were tested at 1.5 T and 3 T for both tuned and detuned coil states. High SAR and regular MRI protocols were applied for 2 coil positions. The measured E field maps display distinct hotspots for all tuned IOCs, which were reduced by at least 40-fold when the IOCs were detuned. Maximum temperature rise was higher when the coils were positioned at the periphery of the phantom with the coil planes parallel to B0. When neither active nor passive detuning was applied, maximum temperature increase of ΔT = 1.3/0.5/1.8 K was found for IFC/tLoop/tLoopRx coils. Hotspots detected by E field measurements, and simulations were consistent. In the simulations, the results were different for homogeneous phantoms compared with full anatomical models. The 2-step test procedure is applicable to different coil types. The results indicate that a risk for radiofrequency-induced heating exists for tuned IOCs, so that adequate detuning circuits need to be integrated in the coils to ensure safe operation.

A Study on the Performance, Structure, Composition, and Release Behavior Changes of Polybutylene Adipate Terephthalic Acid (PBAT) Film during Food Contact

Polybutylene adipate terephthalic acid (PBAT) is an emerging biodegradable material in food packaging. However, concerns have been raised regarding the potential hazards it could pose to food safety. In this study, the changes of PBAT films during food contact and the release of small molecules were inestigated by a multiscale approach. On a macro-scale, the surface roughness of the films increased with the reduction in the concentration of food simulants and the increase in contact temperatures, especially after immersion in acidic food environments. On a micro-scale, the crystallinity (Xc) and degradation indexes (DI) of the films increased by 5.7% - 61.2% and 7.8% - 48.6%, respectively, which led to a decrease in thermal stability. On a scale approaching the molecular level, 2,4-di-tert-butylphenol (2,4-DTBP) was detected by gas chromatography-mass spectrometry (GC-MS/MS) with the highest migration content, and the release behavior of 2,4-DTBP was further investigated by migration kinetics. In addition, terephthalic acid (TPA), a hydrolysis product of PBAT, was detected in acidic food environments by liquid chromatography-mass spectrometry (LC-MS/MS). The results of this study could provide practical guidance and assistance to promote sustainable development in the field of food packaging. Environment ImplicationPBAT film is a new biodegradable material in food packaging that may release small molecular during its contact with food, and pose potential risks to human health. In this study, PBAT films were immersed in a variety of food simulants, and it was found there released a variety of small molecules including TPA, resulting from the hydrolysis of PBAT. The study also revealed that some of these small molecules inhibited cell growth. These findings could promote the safe application of PBAT films in food packaging.

Renewable energy storage using hydrogen produced from seawater membrane-less electrolysis powered by triboelectric nanogenerators

Utilization of widely available seawater for hydrogen generation using robust electrolysis methods can provide sustainable solutions to energy carriers. Sea waves at the same time provide abundant renewable energy that can produce the electricity required for seawater electrolysis. This work presents a novel design for a self-powered hydrogen generation based on membrane-less seawater electrolysis integrated with spring-assisted spherical triboelectric nanogenerators. To streamline fabrication and minimize maintenance expenses, water electrolysis is conducted in a membrane-less electrochemical cell reactor. Employing a mathematical model, the system's performance is analyzed across different catalysts, electrolytes, and operational temperatures. The modeling outcomes indicate that elevating the cell's temperature can lower the necessary potential, enhancing overall electrochemical cell efficiency and decreasing capacitor charging duration. The voltage required for the cell to reach 100 mA cm−2 in the seawater decreases from 2.4 V to 1.9 V as the cell temperature increase from 25 °C to 70 °C. This is due to the decline in the hydrogen and oxygen evolution reaction overpotentials for NPNNS and Ti supported PtPd from 351 mV to 246 mV and 568 mV–394 mV, respectively. Furthermore, increase in the temperature results in an additional 19 % improvement in cell efficiency from 78 % to 97 % and producing hydrogen per cycle during electrolysis of seawater increase from 0.015 μmole to 0.020 μmole.

Ultrafast Raman thermometry in driven YBa2Cu3O6.48

Signatures of photoinduced superconductivity have been reported in cuprate materials subjected to a coherent phonon drive. A “cold” superfluid was extracted from the transient Terahertz conductivity and was seen to coexist with “hot” uncondensed quasiparticles, a hallmark of a driven-dissipative system of which the interplay between coherent and incoherent responses is not well understood. Here, time resolved spontaneous Raman scattering was used to probe the lattice temperature in the photoinduced superconducting state of YBa2Cu3O6.48. An increase in lattice temperature of up to 140 K was observed by measuring the time dependent Raman scattering intensity of an undriven “spectator” phonon mode. This value is consistent with the estimated increase in quasiparticle temperature measured under the same excitation conditions. These temperature changes provide quantitative information on the nature of the driven state and its decay, and may suggest a strategy to optimize this effect. Published by the American Physical Society 2024

Experimental study on the effect of water-heat-force triple-field coupling on the electrical and fatigue properties of cement stabilized layer power generation pavement

Road piezoelectric energy capture technology has developed rapidly in recent years. However, the research of road piezoelectric energy harvester (RPEH) in road environment has rarely been reported. Therefore, in this study, Cement stabilized layer power generation pavement were prepared. Firstly, the output performance of an RPEH under different environmental factors (load, temperature, and water immersion) was tested through indoor tests. Secondly, the 3D simulation model of cement stabilized layer power generation pavement has established, and the output performance of cement stabilized layer power generation pavement has simulated and analyzed under the coupled environment of water, heat and force. Then, the short-term fatigue performance of the RPEH under harsh environments was evaluated. Finally, the fatigue life of cement stabilized layer power generation pavement under extreme environment is predicted by 3D simulation model. The results reveal that the excitation load is the main factor affecting the electrical energy output of the RPEH; The voltage increase is 204.3 % when the excitation load is increased from 0.26 MPa to 1 MPa. Furthermore, an increase in temperature leads to a decrease in the equivalent force of cement stabilized layer and the effect of stress reduction is affected by water immersion environment; When the excitation load is 0.7 MPa, the temperature increases from 20℃ to 50℃, and the immersed environment is 500, 1000 and 1500 ml, the stress attenuation rates are 0.28 %, 0.34 % and −0.025 %, respectively. The water-immersed environment which attenuates the equivalent force and output voltage by more than 40 % and simultaneously attenuates the enhancement effect of the load and temperature on the voltage output of the RPEH. The short-term fatigue degradation rate of piezoelectric ceramics under high temperature and water immersion is 18.5 %, The accuracy of the 3D simulation model in extreme environment was verified through the comparison between the laboratory test results and the 3D simulation results, and the fatigue life of cement stabilized layer power generation pavement was predicted to be greater than five years. The results of this study provide an important reference for the construction design of RPEH for complex road environments.

Effect of Structural Parameters on Output Characteristics of a Novel Self-Supplied Aviation Intelligent Pump

The aviation intelligent pump system is an effective solution to aircraft hydraulic systems’ inefficient power consumption and temperature increase. A self-supplied aviation intelligent pump (SAIP) has a high power-to-weight ratio and compact structure, making it the optimal choice for an intelligent pump. To analyze the output characteristics of a novel aviation intelligent pump, it is crucial to establish an accurate mathematical model that describes its dynamic characteristics. This can be achieved by analyzing the working principle and exploring the influence of critical parameters. The paper introduces the composition and working principle of a self-supplied electro-hydraulic servo variable displacement pump. It then establishes a mathematical model of the whole pump, with a detailed analysis and modeling of the critical variable mechanism and the swash plate assembly’s load moment. A simulation model was created to examine the impact of crucial structural parameters, such as the offset spring’s stiffness and control piston’s diameter, on the output characteristics of the intelligent pump. An experimental platform was also constructed, and the experimental results confirm the accuracy of the SAIP model presented in this paper. The investigation of the output characteristics fully reveals the dynamic performance of the SAIP. This provides the basis for the subsequent design of high-performance flow and pressure control strategies and aids in researching intelligent aircraft hydraulic systems.

Batatas lam leaf extract as a biodegradable corrosion inhibitor for copper in 0.5 M H2SO4 solution

In this study, the Ipomoea Batatas Lam Leaf Extract (IBLE) was obtained through a pure water decoction process. To investigate the corrosion inhibition capabilities of Ipomoea Batatas Lam Leaf Extract (IBLE), a comprehensive approach encompassing electrochemical techniques, X-ray Photoelectron Spectroscopy (XPS), Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM), and theoretical calculations has been employed. The electrochemical test results demonstrate a remarkable corrosion inhibition efficiency of up to 96.7% when utilizing an 800 mg/L concentration of IBLE. As the temperature increases, IBLE can still maintain a high standard of anti-corrosion performance and the corrosion inhibition performance can even maintain more than 95% at a temperature of 315 K. Polarization curve test results demonstrate that IBLE belongs to the mixed corrosion inhibitor, which restrains both anode and cathode reactions of copper electrodes in 0.5 M H2SO4 medium. The EIS test shows that the effective inhibition of the charge transfer process by the adsorption of IBLE onto the interface of copper, as the concentration of IBLE increases, there is a notable and significant rise in it, thus showing a great corrosion inhibition property. The surface morphology test shows that the erosion of the copper surface is significantly suppressed after IBLE adsorbing on the copper surface. XPS test reveals that the active ingredients in IBLE can generate Cu–N bonds on the copper surface, producing chemisorption. Theoretical calculation results reveal that the active ingredients of IBLE have great corrosion suppression property.

Revisiting O(N) σ model at unphysical pion masses and high temperatures

Roy-equation analysis on lattice data of ππ scattering phase shifts at mπ=391 MeV reveals that the lowest f0 meson becomes a bound state under this condition. In addition, there is a pair of complex poles below threshold generated by crossing symmetry [X.-H. Cao , ]. We use the N/D method to partially recover crossing symmetry of the O(N) σ model amplitude at leading order of 1/N expansion, and qualitatively reproduce the pole structure and pole trajectories with varying pion masses as revealed by Roy-equation analyses. The σ pole trajectory with varying temperature is also discussed and found to be similar to its properties when varying mπ. As the temperature increases, the complex σ poles firstly move from the second Riemann sheet to the real axis becoming two virtual state poles, and then one virtual state pole moves to the first sheet turning into a bound state pole and finally tends to the pion pole position at high temperature which is as expected from the chiral symmetry restoration. Our results provide further evidence that the lowest f0 state extracted from experiments and lattice data plays the role of the σ meson in the spontaneous breaking of chiral symmetry. Finally, we also briefly discuss the problems of the effective potential in the situation when mπ and the temperature become large. Published by the American Physical Society 2024

Van Hove Singularity and Enhanced Superconductivity in Ca-Intercalated Bilayer Graphene Induced by Confinement Epitaxy.

We demonstrate the impact of high-density calcium introduction into Ca-intercalated bilayer graphene on a SiC substrate, wherein a metallic layer of Ca has been identified at the interface. We have discerned that the additional Ca layer engenders a free-electron-like band, which subsequently hybridizes with a Dirac band, leading to the emergence of a van Hove singularity. Coinciding with this, there is an increase in the critical temperature for superconductivity. These findings allude to the manifestation of Ca-driven confinement epitaxy, augmenting superconductivity through the enhancement of attractive interactions in a pair of electron and hole bands with flat dispersion around the Fermi level.

Heat stress-induced oviposition behavioral change correlates with sperm damage in the pine sawyer beetle, Monochamus alternatus.

Global climate change is causing an increase in extreme high temperatures (EHTs), which subject insects to unprecedented stress. Behavior plasticity in response to EHTs, particularly oviposition behavior, is important for the persistence and outbreak of insect populations. Investigating the plasticity of oviposition behavior and its underlying mechanisms has theoretical importance to pest management, but knowledge gaps still remain. Herein, we characterized the reproductive traits of Monochamus alternatus, a dominant insect vector of the destructive pine wilt disease, including oviposition behavioral patterns, fecundity, offspring fitness and sperm viability, under simulated heatwave conditions in the laboratory. The results showed that (i) EHTs induced a novel oviposition behavior, whereby females deposited multiple eggs into a single groove rather than laying one egg per groove under normal condition; (ii) EHTs exerted stage- and sex-specific effects on fecundity, offspring fitness and sperm viability; and (iii) there was a significant correlation between frequency of the novel oviposition strategy and sperm viability. We hypothesized that this beetle pest has the ability to flexibly shift towards a low-cost oviposition strategy to counteract the fitness costs caused by heat stress. Taken together, these findings provide a theoretical foundation for personalized pest management strategies in the context of climate change. © 2024 Society of Chemical Industry.

Impact of simultaneous increase in CO2 and temperature on soil aggregates, associated organic carbon, and nutritional quality of rice–wheat grains

AbstractBackgroundFood and nutritional security remain a major thrust area in the under developed and developing countries. These problems are exaggerated by the unprecedented challenges of climate change.AimsThe aim of this study was to assess the impact of climate change on grain quality of wheat and rice genotypes as well as their effect on soil aggregate fractions and aggregate associated carbon.MethodologyIn the context, the present study was formulated by considering four predicted climate scenarios, namely, T0C0 (ambient condition), T0C1 (approx. 25% higher CO2), T1C0 (2°C higher temperature) and T1C1 (25% higher CO2 + 2°C higher temperature) and their impact on grain quality of wheat (HD2967, HD2733, DBW17, and HD3093) and rice (IR83376‐B‐B‐24‐2, IR84895‐B‐127‐CRA‐5‐1‐1, R Bhagwati, and IR64) genotypes as well as soil aggregate fractions and aggregate associated carbon.ResultsThe result revealed that T0C1 has a negative impact on grain nitrogen and protein content. On an average, nitrogen content in wheat and rice showed a decrease of about 15.55% (5.52%–25.32%) and 11.44% (3.33%–23.86%), respectively. Interestingly, the concurrent effect of elevated CO2 and temperature resulted in higher nitrogen and protein content as compared to other climate conditions. Further, P (P) content in the wheat and rice grains also improved under the elevated CO2 condition, whereas the content of potassium was not significantly influenced. Apart from major nutrients, micronutrients (Zn and Fe) were significantly influenced by climatic variables. The study revealed that grain Zn and Fe content of both the crops were reduced due to elevated CO2. The data on soil aggregate fractions revealed that elevated CO2 favors the formation of macro‐aggregate, whereas an increase in temperature favors micro‐aggregate fractions in the soil. Further, the elevation of CO2 also resulted in the accumulation of more carbon in the macro‐aggregates.ConclusionWe conclude that elevated CO2 and temperature cause specific changes in soil aggregate formation and grain nutrient quality. Based on molar ratio of P/Zn and P/Fe, we identified varieties of rice (IR83376‐B‐B‐24‐2) and wheat (HD2733) with higher bioavailability to address the nutritional security with changing climate in developing countries.

Numerical and experimental investigation of temperature dependence vs. mobility degradation on I–V characteristics in N-LDMOS structure

The thermal behavior analysis is undoubtedly the main concern when studying semiconductor devices' and structures' physical mechanics. To the best of our knowledge, simulations studies with an experimental validation of the temperature effect vs. mobility on electrical characteristics in semiconductor devices, specifically in LDMOSFET devices are not well explored in the research literature. Considering this, this paper investigates the thermal influence vs. mobility degradation in the N-LDMOS structure and its impact on electrical performance. It also addresses the temperature impact on channel current Ids and these effects on component performance. The zero-temperature coefficient (ZTC) is evaluated in a N-LDMOS structure using numerical simulations and experimental tests. A study of the drain current behavior at ZTC (IZTC) is proposed in the linear and saturation regions. The influence of temperature mobility degradation on IZTC is analyzed. The consequences of mobility degradation show that the temperature increase gives rise to two contradictory phenomena: firstly, the channel current Ids increases when its value is lower than the current level (IZTC) and secondly, decreases when is higher. These two phenomena are studied by using simulated and experimental approaches, in order to extract and prove the physical aspects near the gate-drain access region (hot spot, electric field, electron concentration, surface carrier density, electron mobility), at the parameter evaluation origin, using SILVACO-TCAD based numerical simulation. Mobility degradation due to the temperature effect is compared to the critical value in N-LDMOS based on I–V behavior obtained with experimentation and simulations. This is explained by the role of negative thermal coefficient in LDMOS transistors. This coefficient proves to be particularly beneficial in terms of mobility gain at low inversion densities.

Chloride Corrosion Process of Concrete with Different Water–Binder Ratios under Variable Temperature Drying–Wetting Cycles

In this paper, four water–binder ratios (w/b) of 0.29, 0.33, 0.39, and 0.46 were designed. A variable test temperature was implemented in the drying–wetting cycle test according to the temperature fluctuations in the actual service environment, and the constant temperature test was established as the control group. The mechanical properties and chloride corrosion resistance of concrete with different w/b ratios under variable temperature drying–wetting cycles, as well as the microstructure changes, phase composition, and damage mechanism inside the concrete, were investigated. The results showed that the mechanical properties of concrete increased first and then decreased with drying–wetting cycles increasing, whereas the chloride corrosion resistance continued to decline. A higher w/b exacerbated the deterioration of the concrete performance. A higher w/b increased the porosity, chloride diffusion depth, and chloride content, thus reducing the resistance of chloride corrosion. Compared with w/b = 0.29, the compressive strength, splitting tensile strength, mass, and relative dynamic elasticity modulus of w/b = 0.46 exposed to 60 drying–wetting cycles decreased by 54.50%, 52.44%, 0.96%, and 6.50%, respectively, while the porosity, peak chloride content, and erosion depth increased by 45.12%, 70.45%, and 45.00%. Compared with the drying–wetting cycle with a constant temperature, the cumulative damage caused by the drying–wetting cycle with a variable temperature was greater, resulting in more severe deterioration of concrete performance. The increase in the test temperature significantly accelerated the diffusion rate, penetration depth, and chemical binding capacity of chloride ions. After 60 drying–wetting cycles, the peak chlorine content and erosion depth of w/b = 0.46 under variable temperature cycles were 15.38% and 10.32% higher than those under a constant temperature, while the compressive strength, splitting tensile strength, mass, and relative dynamic elastic modulus were reduced by 7.76%, 14.81%, 0.33%, and 2.40%, respectively. Microscopic analysis confirmed that higher w/b and variable temperature cycles accelerated the decay of mechanical properties and the decline of chloride corrosion resistance. According to the numerical fitting analysis, the w/b should be 0.29~0.39 under the condition that the mechanical properties and chloride corrosion resistance of concrete are met.

Effect of nano-graphene lubricating oil on particulate matter of a diesel engine

Nano-graphene lubricating oil with appropriate concentration shows excellent performance in reducing friction and wear under different working conditions of diesel engines, and has been widely concerned. Lubricating oil has a significant impact on particulate matter (PM) emissions. At present, there are few studies on the impact of nano-graphene lubricating oil on the physicochemical properties of PM. In order to comprehensively evaluate the impact of nano-graphene lubricating oil on diesel engines, this paper mainly focused on the effects of lubricating oil nano-graphene additives on the particle size distribution and physicochemical properties of PM. The results show that, compared with pure lubricating oil, the total number of nuclear PM and accumulated PM of nano-graphene lubricating oil is significantly increased. The fractal dimension of PM of nano-graphene lubricating oil increases and its structure becomes more compact. The average fringe separation distance of basic carbon particles decreases, the average fringe length increases. The degree of ordering and graphitization of basic carbon particles are higher. The fringe tortuosity of basic carbon particles decreases, and the fluctuation of carbon layer structure of basic carbon particles decreases. Aliphatic substances in PM are basically unchanged, aromatic components and oxygen functional groups increase. The initial PM oxidation temperature and burnout temperature increase, the maximum oxidation rate temperature and combustion characteristic index decrease, and the activation energy increases, making it more difficult to oxidize. This was mainly caused by the higher graphitization degree of PM of nano-graphene lubricating oil and the increased content of aromatic substances.

Tailored Phototherapy Agent by Infection Site in Situ Activated against Methicillin-Resistant S. aureus.

Phototherapy, including photodynamic therapy (PDT) and photothermal therapy (PTT), is a promising treatment approach for multidrug resistant infections. PDT/PTT combination therapy can more efficiently eliminate pathogens without drug resistance. The key to improve the efficacy of photochemotherapy is the utilization efficiency of non-radiation energy of phototherapy agents. Herein, we design a facile phototherapy molecule (SCy-Le) with the enhancement of non-radiative energy transfer by an acid stimulation under a single laser. Introduction of the protonated receptor into SCy-Le results in a distorted intramolecular charge in the infected acidic microenvironment, pH≈5.5, which in turn enhances light capture, reduces the singlet-triplet transition energies (ΔES1-T1), promotes electron system crossing, enhances capacity of ROS generation, and a significant increase in temperature by improving vibrational relaxation. SCy-Le showed more than 99% bacterial killing rate against both methicillin-resistant Staphylococcus aureus (MRSA) and its biofilms in vitro, and caused bacteria-induced wound healing in mice. This work will provide a new perspective for the design of phototherapy agents, and the emerging photochemotherapy will a promising approach to combat the problem of antibiotic resistance. This article is protected by copyright. All rights reserved.

Study on the influencing factors of mechanical properties of anti-icing modified asphalt mortar

Accumulated snow and ice on road surface affect traffic operation. Anti-icing asphalt pavement is widely implemented as an active snow melting technology. However, there are few studies on anti-icing modified asphalt mortar mechanical properties and the effect of mortar materials on the interaction between modified asphalt and anti-icing filler. For this reason, this study investigated the mechanical properties of asphalt including rheological, high-temperature, fatigue and low-temperature properties through frequency and temperature scan, multiple stress creep recovery, linear amplitude scan, and single edge notched beam test. Based on this, the significant factors affecting asphalt mechanical properties were identified by analysis of variance. Subsequently, the Palierne-C-G* parameter was used to quantify the interaction between modified asphalt and anti-icing filler, and the effect of asphalt chemical structure on the interaction was revealed by Fourier Transform Infrared Spectroscopy (FTIR) test. The results indicated that the anti-icing filler significantly improved the high temperature and fatigue resistance of asphalt. Compared with SBS modified asphalt mortar, the mechanical properties of composite modified asphalt mortar were superior. The most significant factor affecting the mechanical properties of SBS modified asphalt mortar was modifier dosage, while the most significant factor affecting the composite modified asphalt mortar was crushed rubber dosage. The interaction showed a decreasing trend with the increase of frequency, while it appeared to increase and then decrease with the increase of temperature. The carbonyl functional group of asphalt correlated best with the interaction between asphalt and filler.

Density functional theory study on the mechanism of water gas shift reaction catalyzed by molybdenum hexacarbonyl in aqueous solvent

The mechanism of the water gas shift reaction (WGSR) catalyzed by Mo(CO)6 in both gaseous and aqueous phases were analyzed using the density functional theory (DFT) method. This study indicates that aqueous phase slightly increased every energy barrier for each step along the reaction path. The turnover frequency (TOF) of the reaction was determined using the energy span model (ESM). The TOF value in the aqueous phase (2.48 × 10−16 s−1) is slightly lower than in the gas phase (6.08 × 10−16 s−1). Actually, the advantages of aqueous phase may be attributed to high solubility and concentration of H2O, CO, OH−. The study of temperature (300–900 K) on energy profile shows that the reaction rate of WGSR can be increased with the increase of temperature. This research filled the gap in understanding the mechanism for the WGSR in aqueous phase, provides a reasonable theoretical foundation for molybdenum-based catalysts development.

Unconventional superconductivity without doping in infinite-layer nickelates under pressure

High-temperature unconventional superconductivity quite generically emerges from doping a strongly correlated parent compound, often (close to) an antiferromagnetic insulator. The recently developed dynamical vertex approximation is a state-of-the-art technique that has quantitatively predicted the superconducting dome of nickelates. Here, we apply it to study the effect of pressure in the infinite-layer nickelate SrxPr1−xNiO2. We reproduce the increase of the critical temperature (Tc) under pressure found in experiment up to 12 GPa. According to our results, Tc can be further increased with higher pressures. Even without Sr-doping the parent compound, PrNiO2, will become a high-temperature superconductor thanks to a strongly enhanced self-doping of the Ni dx2−y2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${d}_{{x}^{2}-{y}^{2}}$$\\end{document} orbital under pressure. With a maximal Tc of 100 K around 100 GPa, nickelate superconductors can reach that of the best cuprates.