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[Introduction] With the increase of operation time of overhead transmission lines and the aggravation of aging and corrosion of equipment, the rusted ground wire replacement is significantly increased. Due to the large cross span of overhead transmission lines and the decrease of mechanical properties of corroded ground wires, there is a high risk in the replacement construction, especially when the same grade crosses multiple high-voltage power lines. Therefore, it is necessary to explore the methods, steps and safety precautions of replacement construction. [Method] Taking the replacement construction of corroded ground wire of a 500 kV transmission line spanning three 220 kV power lines in the same span from Pingguo to Laibin as an example, in order to reduce the risk in the replacement process, the measures were taken, such as wire sealing, two-way protection of steel wire rope installed on the ground wire support, reasonable setting of the traction field, reducing the traction speed of the ground wire and reclosure of the crossing line one by one. [Result] These measures are verified to be safe and effective on site, which can well protect the safety of the power lines across and reduce the risk of construction operations. [Conclusion] These key technologies in construction have important reference significance for future similar operations.

Abstract Hypersonic boundary layer transition is a hot yet challenging problem restricting the development and breakthrough of hypersonic aerodynamics. In recent years, despite great progress made by wind tunnel experiment, transition mechanism and transition prediction, only partial knowledge has been gained so far. In this paper, firstly, the specific scenarios of hypersonic boundary layer transition control are clarified. Secondly, the experimental research progress and mechanism of passive control and active control methods under different hypersonic transition control demands are summarized, with their advantages and disadvantages being analyzed separately. Plasma actuation is easy to produce controllable broadband aerodynamic actuation, which has potential in the field of boundary layer transition control. Hence, the following part of the paper focuses on plasma flow control. The feasibility of plasma actuation to control the hypersonic boundary layer transition is demonstrated and the research ideas are presented. Finally, hypersonic boundary layer transition control methods are summarized and the direction of future research is prospected.

Panax notoginseng is a highly valued perennial medicinal herb in China and is widely used in clinical treatments. The main purpose of this study was to elucidate the changes in the composition of P. notoginseng saponins (PNSs), which are the main bioactive substances, triggered by arbuscular mycorrhizal fungi (AMF) via ultrahigh-performance liquid chromatography–electrospray ionization–tandem mass spectrometry (UPLC–ESI–MS/MS). A total of 202 putative terpenoid metabolites were detected, of which 150 triterpene glycosides were identified, accounting for 74.26% of the total. Correlation analysis, principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS–DA) of the metabolites revealed that the samples treated with AMF (group Ce) could be clearly separated from the CK samples. In total, 49 differential terpene metabolites were identified between the Ce and CK groups, of which 38 and 11 metabolites were upregulated and downregulated, respectively, and most of the upregulated differentially abundant metabolites were mainly triterpene glycosides. The relative abundances of the two major notoginsenosides (MNs), ginsenosides Rd and Re, and 13 rare notoginsenosides (RNs), significantly increased. The differential saponins, especially RNs, were more easily clustered into one branch and had a high positive correlation. It could be concluded that the biosynthesis and accumulation of some RNs share the same pathways as those triggered by AMF. This study provides a new way to obtain more notoginsenoside resources, particularly RNs, and sheds new light on the scientization and rationalization of the use of AMF agents in the ecological planting of medicinal plants. [ABSTRACT FROM AUTHOR]

The aims of our study were to examine whether initial or subsequent adiposity status had a greater effect on hypertension. We collected data in 1992 and again in 2007 from the same group of 597 individuals in the middle age. The subjects were classified into four groups: individuals with a normal body mass index (BMI) in 1992 and 2007 were in Group I; those with a normal BMI in 1992, but became overweight or obese in 2007 were in Group II; those who were overweight or obese in 1992, but had a normal BMI in 2007 were in Group III; and those who were overweight or obese in 1992 and 2007 were in Group IV. Their demographic data were recorded. The relationship between adiposity status and hypertension was analyzed using logistic regression model. The cumulative incidence of hypertension was 35.5%, 56.3%, 50.0%, and 65.1% for Group I to IV, respectively. Compared with Group I, after adjusted factors, the hazard ratio (HR) was 1.80 for Group II (P =.001), 1.40 for Group III (P =.150), and 2.31 for Group IV (P <.001). Adiposity status in 2007 could predict hypertension (OR = 2.5, P <.001), as opposed to the initial adiposity status (P =.148). Subsequently adiposity status could have major effects on hypertension. Our society is very short of public health resources, particularly in developing countries, we should pay more attention to current adiposity status and encourage middle‐aged people to lose weight. [ABSTRACT FROM AUTHOR]

Yunnan plays a pivotal role in transmitting electricity from west to east within China's Southern Power Grid. During 7–13 January 2021, a large-scale continuous ice-covering event of ultra-high voltage (UHV) transmission lines occurred in the Qujing area of eastern Yunnan Province. Based on ERA5 reanalysis data and meteorological observation data of UHV transmission line icing in China's Southern Power Grid, the synoptic causes of the icing are comprehensively analyzed from various perspectives, including weather situations, vertical stratification of temperature and humidity, local meteorological elements, and atmospheric circulation indices. The results indicate a strong East Asian trough and a blocking high directing northern airflow southward ahead of the ridge. Cold air enters the Qujing area and combines with warm and moist air from the subtropical high pressure of 50–110° E. As warm and cold air masses form a quasi-stationary front over the northern mountainous area of Qujing due to topographic uplift, the mechanism of "supercooling and warm rain" caused by the "warm–cold" temperature profile structure leads to freezing rain events. Large-scale circulation indices in the Siberian High, East Asian Trough, and 50–110° E Subtropical High regions provided clear precursor signals within 0–2 days before the icing events. [ABSTRACT FROM AUTHOR]