Oxide perovskite BaSnO3: A promising high-temperature thermoelectric material for transparent conducting oxides

The new technology of energy conversion must be developed to ensure energy sustainability. Thermoelectric (TE) materials provide an effective means to solve the energy crisis. As a potential TE candidate, the TE properties of perovskite have received extensively attention. We here investigate the TE transport properties of the transparent conducting oxide (TCO) BaSnO3 by first-principles calculations. We find that the BaSnO3 perovskite exhibits outstanding dynamic and thermal stabilities, which provide excellent electronic and thermal transport properties simultaneously. These properties contribute to the remarkable Seebeck coefficient and power factor, which gives rise to the ZT of n-1.03 and p-3.64 at 900 K. Additionally, doping and nanostructure open prospects for effectively improving the TE properties of BaSnO3. Our work provides a basis for further optimizing the TE transport properties of cubic BaSnO3 and may have worthwhile practical significance for applying cubic perovskite to the high-temperature thermoelectric field.Comment: 29 pages,6 figures,1 tabl

Two distinct superconducting states controlled by orientation of local wrinkles in LiFeAs

We observe two types of superconducting states controlled by orientations of local wrinkles on the surface of LiFeAs. Using scanning tunneling microscopy/spectroscopy, we find type-I wrinkles enlarge the superconducting gaps and enhance the transition temperature, whereas type-II wrinkles significantly suppress the superconducting gaps. The vortices on wrinkles show a C2 symmetry, indicating the strain effects on the wrinkles. A discontinuous switch of superconductivity occurs at the border between two different wrinkles. Our results demonstrate that the local strain effect could affect superconducting order parameter of LiFeAs with a possible Lifshitz transition, by alternating crystal structure in different directions.Comment: 21 pages, 9 figure

Corona Onset Characteristics of Bundle Conductors in UHV AC Power Lines at 2200 m Altitude

The corona onset characteristic of bundle conductors is an important limiting factor for the design of UHV AC power lines in high-altitude areas. An experimental study on the corona characteristics of 8 × LGJ630, 6 × LGJ720, 8 × LGJ720 and 10 × LGJ720 bundle conductors commonly used in UHV power lines under dry and wet conductor conditions, as well as artificial moderate and heavy rain conditions, was conducted in Ping’an County, Xining City (elevation 2200 m). By using the tangent line method, the corona onset voltages and onset electric field of four types of conductors at high altitudes are obtained for the first time. In addition, the calculation model of corona onset voltage considering the outer strands’ effect on the electric field and the geometric factor in the corona cage in high altitude areas is established. The comparison of the calculation results and experimental results under dry conditions verifies the model’s correctness. Based on the results, an optimal selection scheme for high altitudes is proposed. The roughness coefficient was also calculated and analysed: the roughness coefficient of bundled conductors was between 0.59 and 0.77, and the roughness coefficient of the wet conductor was between the dry and rainy conditions. Both the experimental data and the calculation model can provide a reference for conductor selection for UHV AC power lines for use in high-altitude areas

Research of long-span bridge and traffic system subjected to winds: A system and multi-hazard perspective

Wind effects on long-span bridges and moving vehicles have drawn considerable attention during the past years. Effectively considering the dynamic interactions between wind, vehicles and bridges and rationally assessing the bridge performance becomes essential to this type of critical infrastructure system. The impact of strong winds on long-span bridge transportation systems has received a lot of attention during the past decades. Meanwhile, low to moderate winds may serve as a type of important service load acting on the long-span bridge transportation system, along with other extreme or hazardous loads. In addition to the structural integrity, it is also important to appropriately assess the vehicle performance, such as safety and comforting issues, under wind so that the associated risks can be identified and mitigated. This paper summarizes some recent advances on the research of wind effects on long-span bridge and traffic systems with a focus on the efforts from a system and multi-hazard perspective

The Dynamic Relationship among Bank Credit, House Prices and Carbon Dioxide Emissions in China

This paper explores the dynamic relationship among bank credit, house prices and carbon dioxide emissions in China by systematically analyzing related data from January 2000 to December 2019 with the help of the time-varying parameter vector autoregression with stochastic volatility (TVP-SV-VAR) model and the Bayesian DCC-GARCH model. Empirical results show the expansion of bank credit significantly drives up house prices and increases carbon dioxide emissions in mosttimes. The rise in house prices inhibits the expansion of bank credit but increases carbon dioxide emissions and aggravates environment pollution, and that the increase in carbon dioxide is helpful to stimulate bank credit expansion and house price rise. In addition, bank credit and house prices are most relevant, followed by bank credit and carbon dioxide emissions, then by house prices and carbon dioxide emissions. Therefore, we believe that in order to stabilize skyrocketing house prices, restrain carbon dioxide emissions, and secure a stable and healthy macro-economy, the government should strengthen management of bank credit, and effectively control its total volume

Magnetic Solid-Phase Extraction of Dichlorodiphenyltrichloroethane and Its Metabolites from Environmental Water Samples Using Ionic Liquid Modified Magnetic Multiwalled Carbon Nanotube/Zeolitic Imidazolate Framework-8 as Sorbent

As persistent organic pollutants, dichlorodiphenyltrichloroethanes (DDTs) and their metabolites pose considerable risks to human health and the environment. Therefore, monitoring DDTs in the environment is essential. Here, we developed a green, simple, and effective magnetic solid-phase extraction (MSPE) method coupled with gas chromatography tandem triple-quadrupole mass spectrometry to determine the DDT content of environmental water samples. A magnetic ionic liquid (IL) adsorbent was developed based on a modified magnetic multiwalled carbon nanotube/zeolitic imidazolate framework-8 (MM/ZIF-8/IL), synthesized by immobilizing the IL on the surface of MM/ZIF-8. We confirmed successful synthesis of MM/ZIF-8/IL by material characterization, and our results suggested that the MM/ZIF-8/IL had a high Brunauer–Emmett–Teller surface area (159.9 m2 g−1), good thermostability (<800 °C), and a high degree of superparamagnetism (52.9 emu g−1). Several experimental conditions affecting the MSPE efficiency were optimized. Under the best conditions, good detection linearity was achieved (0.5–500 µg L−1) with determination coefficients ranging from 0.9927 to 0.9971. The lower limits of detection (0.0016–0.0072 µg L−1) also had good precision, having an intraday relative standard deviation (RSD) ≤ 6.5% and an interday RSD ≤ 8.9%. Finally, we used the as-developed method to determine DDT levels in environmental water samples