Search

Bi1−xBaxFeO3 (BBFO, x = 0, 0.03, 0.1) thin films were epitaxially grown on SrRuO3-buffered SrTiO3 (001) substrates by pulsed laser deposition. With increasing Ba content, the BBFO thin films show significantly reduced leakage currents but suppressed ferroelectric polarization. X-ray diffraction reciprocal space mappings and Raman spectra indicate a structural evolution from a rhombohedral-like to tetragonal-like phase in the BBFO thin films. Optical absorption and photoelectron spectroscopy measurements demonstrate a modulation of energy band structures in the BBFO thin films. With A-site Ba acceptor doping, the BBFO thin films exhibit a blue-shift of optical bandgap and an increase in work function. The energy positions of conduction and valence bands of the BBFO thin films have been modulated, and the Fermi level shifts down to the center of the forbidden band, but acceptor-doped BFO thin films still show n-type conduction. The presence of extra oxygen vacancies by acceptor doping is supposed to make contribution to conduction behavior. This study provides a method to manipulate the functional properties and gives insights into the physics of Ba doping in BFO thin films. [ABSTRACT FROM AUTHOR]

The traditional mine gas sensor is vulnerable to the influence of temperature and ambient humidity and other factors, resulting in low stability. In order to solve the above problem, based on the principle of local surface plasmon resonance (LSPR) and the phase change characteristics of vanadium dioxide (VO2), a kind of metasurface dual-gas sensor based on VO2 is designed. The sensor structure is composed of three layers, and the surface is composed of multi-layer metal-dielectric-metal (MDM) structure. According to the phase change characteristics of VO2, the metal plate is heated in the form of resistance heating by changing the applied bias voltage. The temperature of VO2 is carefully controlled, and the different states of VO2 are simulated by changing the conductivity of VO2. When VO2 is in a high-temperature metal state, the upper three layers form MDM structure. VO2 shows metal properties and excites local surface plasmon resonance (LSPR) at 1721.3 nm to realize methane detection. The sensor's absorptance reaches 94.3%, and the methane sensitivity reaches 4.21 nm/%. When VO2 is in a low-temperature insulation state, the lower three layers form MDM structure. LSPR is excited at 2694.6 nm to realize hydrogen detection. The sensor's absorptance reaches 95.9%, and the hydrogen sensitivity reaches 2.10 nm/%. When the environmental refractive index changes, the absorption peaks of VO2 in both states are red-shifted and linear,which can be used to detect the change of the environmental refractive index. In order to verify the feasibility of the sensor, six different concentrations of methane, hydrogen and four different environmental refractive indexes are simulated and analyzed. The results show that the metasurface dual-gas sensor based on VO2 can effectively detect methane and hydrogen with lower concentration. The sensitivity is greatly improved compared with the existing gas sensors. The error between the calculated and theoretical values of the resonant peak shift and the environmental refractive index change and the methane volume fraction change is very small. This indicates that the sensor has high accuracy. By analyzing the relationship between the environmental refractive index and the resonant wavelength, it is concluded that the sensor also has high detection sensitivity when the environmental refractive index changes.

The Tibetan Plateau has exhibited a discernible trend towards increased precipitation over the past 50 years. However, previous research predominantly focused on thermal stability of permafrost without the consideration of water flux boundary conditions, and therefore ignored the dynamics of water migration and its impacts on the embankment stability. To bridge this gap, a novel water-heat transfer model incorporating rainfall and water migration was developed and subsequently validated using monitored data. Comparative analyses were then conducted across three distinct rainfall intensities to investigate the variations in the moisture and temperature of superficial soil. Results indicate rainfall events exert a notable cooling effect during warm seasons but have little influence on cooling during cold seasons. By increasing the latent heat of evaporation, sensible heat and reducing the soil heat flux, rainfall results in embankment cooling, and the cooling effect correlates positively with rainfall intensity. Disregarding the water flux boundary conditions will overestimate the embankment temperature and underestimate the variation of water content, especially at the superficial soil. Rainfall results in a decline in water vapor flux and an increase in liquid water flux, which facilitates rapid downward transport and accumulation of liquid water. Despite the increased convective heat transfer of liquid water, the decrease in heat conduction, latent heat of evaporation and convective heat transfer of water vapor in the embankment is more pronounced. Rainfall changes the stability of permafrost embankment mainly by adjusting the energy distribution, which delays temperature increases in the underlying permafrost. When predicting the stability of permafrost, it is recommended to incorporate the water flux boundary conditions. [ABSTRACT FROM AUTHOR]

Sevoflurane (Sev) is a commonly used inhalation anaesthetic that has been shown to cause hippocampus dysfunction through multiple underlying molecular processes, including mitochondrial malfunction, oxidative stress and inflammation. Dihydromyricetin (DHM) is a 2,3‐dihydroflavonoid with various biological properties, such as anti‐inflammation and anti‐oxidative stress. The purpose of this study was to investigate the effect of DHM on Sev‐induced neuronal dysfunction. HT22 cells were incubated with 10, 20 and 30 μM of DHM for 24 h, and then stimulated with 4% Sev for 6 h. The effects and mechanism of DHM on inflammation, oxidative stress and mitochondrial dysfunction were explored in Sev‐induced HT22 cells by Cell Counting Kit‐8, flow cytometry, enzyme‐linked immunosorbent assay, reverse transcription‐quantitative polymerase chain reaction, colorimetric detections, detection of the level of reactive oxygen species (ROS), mitochondrial ROS and mitochondrial membrane potential (MMP), immunofluorescence and western blotting. Our results showed that DHM increased Sev‐induced cell viability of HT22 cells. Pretreatment with DHM attenuated apoptosis, inflammation, oxidative stress and mitochondrial dysfunction in Sev‐elicited HT22 cells by remedying the abnormality of the indicators involved in these progresses, including apoptosis rate, the cleaved‐caspase 3 expression, as well as the level of tumour necrosis factor α, interleukin (IL)‐1β, IL‐6, malondialdehyde, superoxide dismutase, catalase, ROS, mitochondrial ROS and MMP. Mechanically, pretreatment with DHM restored the Sev‐induced the expression of SIRT1/FOXO3a pathway in HT22 cells. Blocking of SIRT1 counteracted the mitigatory effect of DHM on apoptosis, inflammation, oxidative stress and mitochondrial dysfunction in Sev‐elicited HT22 cells. Collectively, pretreatment with DHM improved inflammation, oxidative stress and mitochondrial dysfunction via SIRT1/FOXO3a pathway in Sev‐induced HT22 cells. [ABSTRACT FROM AUTHOR]

Adopting zero-carbon fuels, like hydrogen, can significantly reduce environmental harm and pave the way for a decarbonised trajectory with zero carbon emissions. The hydrogen internal combustion engine (ICE) technology has demonstrated its reliability and capacity to seamlessly integrate into the current ICE platform, originally designed for diesel and gasoline operation. The direct utilisation of pure hydrogen eradicates steady-state carbon dioxide and hydrocarbon emissions. It is important to highlight that efforts to comprehend and comprehensively tackle NOx emissions are underway. A comprehensive study was carried out to assess the NOx emissions for a hydrogen ICE with different injection modes from gasoline. The study involved varying the relative air-to-fuel ratio (AFR) from stoichiometric to the lean-burn limit in a boosted spark ignition (SI) engine fuelled with gasoline or hydrogen. A fast NOx emissions analyser was employed to measure the instantaneous NO and NO2 emissions in the engine exhaust. The study provides a detailed analysis of NOx emissions, including steady-state averaged emissions, average crank angle domain NOx distribution and emissions, in-cylinder pressure analysis, as well as time and cycle analyses of NOx emissions' temporal and cyclic variations. The primary discovery was that NOx emissions are almost zero between lambda 2.75 and 3.7, and hydrogen produces 13.8% less NOx emissions than gasoline at stoichiometric operation. Finally, the full NOx time analysis revealed that the consistency of NOx emissions is higher with hydrogen than with gasoline by using a novel approach by identifying the coefficient of variation of the NOx emission of each cycle. [ABSTRACT FROM AUTHOR]

Although it is well known that properly used Rollover Protective Structures (ROPS) can virtually prevent agricultural tractor rollover fatalities, the U.S. still has hundreds of these fatalities per year. An estimated 1.6 million tractors are not equipped with ROPS. Many of these tractors do not have ROPS commercially available although they were originally designed to support a ROPS. Some tractors have foldable ROPS that are not used properly. Other ROPS, although meet appropriate performance standards, are not effective at eliminating continuous rolls. To meet this need, a Computer-based ROPS Design Program (CRDP) was developed to quickly generate ROPS designs based on agricultural tractor weights and dimensions. The ROPS designed with the CRDP for the Allis Chalmers 5040 tractor successfully passed the SAE J2194 static longitudinal, transverse, and vertical tests. A simple foldable ROPS lift assist was designed and tested to ease in the raising and lowering of ROPS; decreasing the raising torque from 90 Nm to less than 50 Nm, while also lowering the resisting torque to lower the ROPS. A model to determine the critical ROPS height CRH based on off-road vehicle dimensions and center of gravity (CG) height was developed and evaluated.