International audiencePollen data from China for 6000 and 18,000 C-14 yr BP Were compiled and used to reconstruct palaeovegetation patterns, using complete taxon lists where possible and a biomization procedure that entailed the assignment of 645 pollen taxa to plant functional types. A set of 658 modern pollen samples spanning all biomes and regions provided a comprehensive test for this procedure and showed convincing agreement between reconstructed biomes and present natural vegetation types, both geographically and in terms of the elevation gradients in mountain regions of north-eastern and south-western China. The 6000 C-14 yr BP map confirms earlier studies in showing that the forest biomes in eastern China were systematically shifted northwards and extended westwards during the mid-Holocene. Tropical rain forest occurred on mainland China at sites characterized today by either tropical seasonal or broadleaved evergreen/warm mixed forest. Broadleaved evergreen/warm mixed forest occurred further north than today, and at higher elevation sites within the modern latitudinal range of this biome. The northern limit of temperate deciduous forest was shifted c. 800 km north relative to today. The 18,000 C-14 yr BP map shows that steppe and even desert vegetation extended to the modem coast of eastern China at the last glacial maximum, replacing today's temperate deciduous forest. Tropical forests were excluded from China and broadleaved evergreen/warm mixed forest had retreated to tropical latitudes, while taiga extended southwards to c. 43 degreesN

Proxy-based reconstructions and modeling of Holocene spatiotemporal precipitation patterns for China and Mongolia have hitherto yielded contradictory results indicating that the basic mechanisms behind the East Asian Summer Monsoon and its interaction with the westerly jet stream remain poorly understood. We present quantitative reconstructions of Holocene precipitation derived from 101 fossil pollen records and analyse them with the help of a minimal empirical model. We show that the westerly jet-stream axis shifted gradually southward and became less tilted since the middle Holocene. This was tracked by the summer monsoon rain band resulting in an early-Holocene precipitation maximum over most of western China, a mid-Holocene maximum in north-central and northeastern China, and a late-Holocene maximum in southeastern China. Our results suggest that a correct simulation of the orientation and position of the westerly jet stream is crucial to the reliable prediction of precipitation patterns in China and Mongolia.

The strategy of turning ferroelectric into relaxor is feasible and effective to boost the energy density and efficiency for sodium bismuth titanate-based bulk ceramics.

Recently, ceramic capacitors with fast charge–discharge performance and excellent energy storage characteristics have received considerable attention. Novel NaNbO3-based lead-free ceramics (0.80NaNbO3-0.20SrTiO3, abbreviated as 0.80NN-0.20ST), featuring ultrahigh energy storage density, ultrahigh power density, and ultrafast discharge performance, were designed and prepared in this study. These 0.80NN-0.20ST ceramics exhibited a high breakdown strength of 323 kV/cm, attributable to their small grain size and dense microstructure, a recoverable energy storage density of 3.02 J/cm3, and an energy storage efficiency of 80.7% at an applied electric field of 310 kV/cm. The excellent stability of energy storage properties in frequency (0.1–1000 Hz), temperature (20–120 °C), and fatigue resistance (cycle number: 105) were also observed in the 0.80NN-0.20ST ceramics. In contrast with other recently reported lead-free ceramic-based dielectric capacitors, the 0.80NN-0.20ST ceramics display a high energy storage efficiency combined with a high recoverable energy storage density, which indicates that they have wide application foreground and potential in the field of energy storage. These ceramics also show a considerable current density of 677 A/cm2, an ultrahigh power density of 23.7 MW/cm3, and a short release duration (∼225 ns). This study brings the NaNbO3-based ceramics into a new chapter of research and application of energy storage dielectric capacitors.