Slidephononics: Tailoring Thermal Transport Properties by van der Waals Sliding

By interlayer sliding in van der Waals (vdW) materials, the switching electric polarization of ultrathin ferroelectric materials leads to the widely studied slidetronics. In this work, we report that such sliding can further tailor anharmonic effects and hence thermal transport properties due to the changed intrinsic coupling between atomic layers. And we propose an unprecedented concept dubbed as slidephononics, where the phonons and associated physical properties can be controlled by varying the intrinsic stacking configurations of slidetronic vdW materials. Based on the state-of-the-art first-principles calculations, it is demonstrated that the thermal conductivity of boron nitride (BN) bilayers can be significantly modulated (by up to four times) along the sliding pathways. Detailed analysis reveals that the variation of thermal conductivities can be attributed to the tunable (de-)coupling of the out-of-plane acoustic phonon branches with the other phonon modes, which is induced by the interlayer charge transfer. Such strongly modulated thermal conductivity via interlayer sliding in vdW materials paves the way to engineer thermal management materials in emerging vdW electronic devices, which would shed light on future studies of slidephononics

Restoration of soil quality of degraded grassland can be accelerated by reseeding in an arid area of Northwest China

Grassland restoration measures control soil degradation and improve soil quality (SQ) worldwide, but there is little knowledge about the effectiveness of restoration measures affecting SQ in arid areas, and the restoration rate of degraded grasslands to natural restoration grasslands and reseeded grasslands remains unclear. To establish a soil quality index (SQI) to evaluate the effects of different grassland restoration measures on SQ, continuous grazing grassland (CG) (as a reference), grazing exclusion grassland (EX), and reseeding grassland (RS) were selected and sampled in the arid desert steppe. Two soil indicator selection methods were conducted (total data set (TDS) and minimum data set (MDS)), followed by three SQ indices (additive soil quality index (SQIa), weighted additive soil quality index (SQIw), and Nemoro soil quality index (SQIn)). The results indicated that SQ was better assessed using the SQIw (R2 = 0.55) compared to SQIa and SQIn for indication differences among the treatments due to the larger coefficient of variance. The SQIw-MDS value in CG grassland was 46% and 68% lower than that of EX grassland and RS grassland, respectively. Our findings provided evidence that restoration practices of grazing exclusion and reseeding can significantly improve the SQ in the arid desert steppe, and native plant reseeded can accelerate soil quality restoration