Wind and sand control features are important tools for limiting desertification. Sand barriers are one of the oldest engineering measures used to reduce wind-sand hazards. Their efficacy and exact mechanism by which they work has remained a topic of scientific debate however. Sediment grain-size distributions can help constrain their utility and function. This research analyzed sediment grain size distributions in samples collected from areas around six different types of sand barriers installed along the southeastern margin of the Tengger Desert. Results were compared with sediment from a bare dune area (no barriers) used as a control. The barrier area samples contained high proportions of coarse sand and relatively low proportions of silty sand and very fine sand. Fine and medium sand were present but clay was not. The lower proportions of fine sand and higher proportions of coarse sand relative to bare dunes documented an effective reduction in aeolian transport by the barriers. Samples from the barrier areas also showed poorer sorting relative to bare dune areas. This appeared as lower kurtosis values and wider frequency distribution curves relative to those measured from bare dunes samples. The wider cumulative frequency curves for samples from the barrier areas likely reflects the higher proportion of coarse-grained material. The Straw/1.5 and PLA/1 barrier types hosted greater sediment accumulation than that observed for the other barrier types (Straw/1, PLA/1.5, Mixed/1 and Mixed/1.5). Sediment grain size distributions showed that the base and middle slope areas of the dune experienced deposition, while the top of the dunes experienced erosion. The Straw/1 barrier (straw installed as a 1 × 1 m grid) performed best in terms of installation costs and protective effects for the study area. This study demonstrates how sediment grain size distributions can be used as quantitative proxies for sand barrier performance in reducing desertification.

As the dimensions of transistors have scaled down over the last decades, technology has evolved from planar silicon (Si) to silicon-on-insulator (SOI) to FinFETs to counter in particular short channel effects. To further improve the electrostatics of field-effect transistors (FETs), researchers recently are exploring the use of stacked gate-all-around Si nano-sheet device structures [1]. These novel devices, like FinFETs, give rise to a larger effective channel width for the same footprint and thus allow for higher current drives. The ultimate extension of such a structure would utilize an atomically thin sheet of semiconductor, which makes two-dimensional (2D) transition metal dichalcogenides (TMDs) an ideal choice for applications that rely on the vertical stacking of multiple 2D sheets. In this work we demonstrate for the first time the three-dimensional (3D) integration of two vertically stacked MoS ₂ FETs which shows promising performance specs towards high current drives.

This study describes the effects of coal mine collapse on soil physical and chemical properties in the semi-arid Bulianta mining area of northwest China. Statistical analysis of soil data from 2006, 2012 and 2019 show systematic long term changes of soil physical and chemical properties in response to a 2004 subsidence event. Results show that soil moisture content increased while soil bulk density (SBD) decreased gradually with the passage of time. Samples from different years since the subsidence event showed no significant difference in soil pH (P>0.05). The 0-5 cm soil layers showed the highest organic matter levels but values decreased with soil depth. The average organic matter content of soils in the subsided area increased with time since the subsidence event. Variation coefficients and average rate of change for available nitrogen (AN), available phosphorus (AP) and available potassium (AK) all decreased as contents tended to stabilize over time. Changes in soil physicochemical properties caused by subsidence represent long term economic, social and environmental costs. The results from this study demonstrate the benefits of early stage remediation or preemptive avoidance of risks posed by mine construction. They also provide references for long term monitoring of soil quality and restoration of mining areas.