TianQin is a planned space-based gravitational wave (GW) observatory consisting of three Earth-orbiting satellites with an orbital radius of about $10^5 \, {\rm km}$. The satellites will form an equilateral triangle constellation the plane of which is nearly perpendicular to the ecliptic plane. TianQin aims to detect GWs between $10^{-4} \, {\rm Hz}$ and $1 \, {\rm Hz}$ that can be generated by a wide variety of important astrophysical and cosmological sources, including the inspiral of Galactic ultra-compact binaries, the inspiral of stellar-mass black hole binaries, extreme mass ratio inspirals, the merger of massive black hole binaries, and possibly the energetic processes in the very early universe and exotic sources such as cosmic strings. In order to start science operations around 2035, a roadmap called the 0123 plan is being used to bring the key technologies of TianQin to maturity, supported by the construction of a series of research facilities on the ground. Two major projects of the 0123 plan are being carried out. In this process, the team has created a new-generation $17 \, {\rm cm}$ single-body hollow corner-cube retro-reflector which was launched with the QueQiao satellite on 21 May 2018; a new laser-ranging station equipped with a $1.2 \, {\rm m}$ telescope has been constructed and the station has successfully ranged to all five retro-reflectors on the Moon; and the TianQin-1 experimental satellite was launched on 20 December 2019—the first-round result shows that the satellite has exceeded all of its mission requirements.

Quantitative methods were used to examine soil properties and their spatial heterogeneity in a 0-year fenced mobile dune (MD0), an 11-year fenced mobile dune (MD11) and a 20-year fenced mobile dune (MD20) in Horqin Sandy Land, Northern China. The objective of the study was to assess the effect of vegetation restoration on heterogeneity of soil properties in sand dunes and to provide a concept model to describe the relationship between vegetation succession and spatial heterogeneity variation of soil properties in the dunes. The results showed that the average values of vegetation cover, species number and diversity, soil organic carbon (C), total nitrogen (N), and electrical conductivity (EC) increased with the increase in fenced age of mobile dunes, while soil water content (0-20 cm) showed the reverse trend. Geostatistical analysis revealed that the spatial heterogeneity of soil organic C, total N, EC, very fine sand content, and soil water content (0-20 cm) increased from MD0 to MD11 with succession from sand pioneer plant to shrub species then decreased from MD11 to MD20 due to continuous development of herbaceous plants. Canonical correspondence analysis (CCA) showed that there was a relatively high correspondence between vegetation and soil factors, suggesting that the major gradients relating soil organic C, total N, EC, pH, slope, very fine sand content, and soil water content are the main factors for the distribution of dune plants and account for 68.1% of the species-environment relationship among the three sites. In addition, the distribution of the sand pioneer plant was positively related to the relative height of the sampling site and soil water content, and that of most herbaceous plants were determined by soil organic C, total N, EC, pH, and very fine sand content in mobile dunes. The conceptual model of relationship between vegetation succession and spatial heterogeneity of soil properties in mobile dunes suggests spatial patterns of soil properties are most strongly related to plant-induced heterogeneity in dune ecosystems prone to wind erosion, and conversely, the magnitude and degree of spatial heterogeneity in soil properties can influence the plant distribution pattern and vegetation succession of mobile dunes.

No abstract

A new strategy of constructing an additional heterojunction on the surface of epitaxially grown Ga 2 O 3 film with a distorted lattice is proposed to solve the problem of low external quantum efficiency (EQE) in traditional Ga 2 O 3 heterojunction photovoltaic devices. Experimentally, an organic-inorganic hybrid poly(3,4-ethylenedioxythiophene):polystyrene sulfonate/Ga 2 O 3 /p-type Si solar-blind ultraviolet (SBUV) photovoltaic detector is constructed to achieve an ultrahigh EQE of ≈15% at 0 V bias, which is 1-2 orders of magnitude higher than that of the Ga 2 O 3 photovoltaic devices reported previously. Here, an enhanced mechanism of photogenerated carrier separation efficiency induced by dual built-in fields is proposed to explain the high EQE of Ga 2 O 3 SBUV photovoltaic devices. In addition, the organic-inorganic hybrid detector displays a high SBUV-visible rejection ratio (R 255 nm /R 405 nm of ≈450) and fast response speed (rise time of 60 ms and decay time of 88 ms). All these results indicate that the strategy proposed could provide reference for the fabrication of high-performance Ga 2 O 3 SBUV photovoltaic detectors.