Design
and synthesis of air-stable and easily tailored high-performance
single-molecule magnets (SMMs) are of great significance toward the
implementation of SMMs in molecular-based magneto-electronic devices.
Here, by introducing electron-withdrawing fluorinated substituents on equatorial
ligand, two chiral Dy(III) macrocyclic complexes, RRRR-Dy-D
6hF12 (1) and SSSS-Dy-D
6hF12 (2), with a record anisotropy barrier exceeding
1800 K and the longest relaxation time approaching 2500 s at 2.0 K
for all known air-stable SMMs, were obtained. The nearly perfect axiality
of the ground Kramers doublet (KD) enables the open hysteresis loops
up to 20 K in the magnetically diluted sample. It is notable that
they are structurally rigid with high thermal stability and the apical
ligand can be tailored to carry proper surface-binding groups. This
finding not only improves the magnetic properties for air-stable SMMs
but also provides a new avenue for deposition of SMMs on surfaces.
For thousands of years, humans have created different types of terraces in different sloping conditions, meant to mitigate flood risks, reduce soil erosion and conserve water. These anthropogenic landscapes can be found in tropical and subtropical rainforests, deserts, and arid and semiarid mountains across the globe. Despite the long history, the roles of and the mechanisms by which terracing improves ecosystem services (ESs) remain poorly understood. Using literature synthesis and quantitative analysis, the worldwide types, distributions, major benefits and issues of terracing are presented in this review. A key terracing indicator, defined as the ratio of different ESs under terraced and non-terraced slopes (δ), was used to quantify the role of terracing in providing ESs. Our results indicated that ESs provided by terracing was generally positive because the mean values of δ were mostly greater than one. The most prominent role of terracing was found in erosion control (11.46 ± 2.34), followed by runoff reduction (2.60 ± 1.79), biomass accumulation (1.94 ± 0.59), soil water recharge (1.20 ± 0.23), and nutrient enhancement (1.20 ± 0.48). Terracing, to a lesser extent, could also enhance the survival rates of plant seedlings, promote ecosystem restoration, and increase crop yields. While slopes experiencing severe human disturbance (e.g., overgrazing and deforestation) can generally become more stable after terracing, negative effects of terracing may occur in poorly-designed or poorly-managed terraces. Among the reasons are the lack of environmental legislation, changes in traditional concepts and lifestyles of local people, as well as price decreases for agricultural products. All of these can accelerate terrace abandonment and degradation. In light of these findings, possible solutions regarding socio-economic changes and techniques to improve already degraded terraces are discussed.
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