Abstract. The Tibetan Plateau (TP) has the largest areas of permafrost terrain in the mid-and low-latitude regions of the world. Some permafrost distribution maps have been compiled but, due to limited data sources, ambiguous criteria, inadequate validation, and deficiency of high-quality spatial data sets, there is high uncertainty in the mapping of the permafrost distribution on the TP. We generated a new permafrost map based on freezing and thawing indices from modified Moderate Resolution Imaging Spectroradiometer (MODIS) land surface temperatures (LSTs) and validated this map using various ground-based data sets. The soil thermal properties of five soil types across the TP were estimated according to an empirical equation and soil properties (moisture content and bulk density). The temperature at the top of permafrost (TTOP) model was applied to simulate the permafrost distribution. Permafrost, seasonally frozen ground, and unfrozen ground covered areas of 1.06 × 10 6 km 2 (0.97-1.15 × 10 6 km 2 , 90 % confidence interval) (40 %), 1.46 × 10 6 (56 %), and 0.03 × 10 6 km 2 (1 %), respectively, excluding glaciers and lakes. Ground-based observations of the permafrost distribution across the five investigated regions (IRs, located in the transition zones of the permafrost and seasonally frozen ground) and three highway transects (across the entire permafrost regions from north to south) were used to validate the model. Validation results showed that the kappa coefficient varied from 0.38 to 0.78 with a mean of 0.57 for the five IRs and 0.62 to 0.74 with a mean of 0.68 within the three transects. Compared with earlier studies, the TTOP modelling results show greater accuracy. The results provide more detailed information on the permafrost distribution and basic data for use in future research on the Tibetan Plateau permafrost.

Nitrogen (N) fertilization affects the rate of soil organic carbon (SOC) decomposition by regulating extracellular enzyme activities (EEA). Extracellular enzymes have not been represented in global biogeochemical models. Understanding the relationships among EEA and SOC, soil N (TN), and soil microbial biomass carbon (MBC) under N fertilization would enable modeling of the influence of EEA on SOC decomposition. Based on 65 published studies, we synthesized the activities of α-1,4-glucosidase (AG), β-1,4-glucosidase (BG), β-D-cellobiosidase (CBH), β-1,4-xylosidase (BX, β-1,4-N-acetyl-glucosaminidase (NAG), leucineamino peptidase (LAP), urease (UREA), acid phosphatase (AP), phenol oxidase (PHO), and peroxidase (PEO) in response to N fertilization. The proxy variables for hydrolytic C acquisition enzymes (C-acq), N acquisition (N-acq), and oxidative decomposition (OX) were calculated as the sum of AG, BG, CBH and BX; AG and LAP; PHO and PEO, respectively. The relationships between response ratios (RRs) of EEA and SOC, TN, or MBC were explored when they were reported simultaneously. Results showed that N fertilization significantly increased CBH, C-acq, AP, BX, BG, AG, and UREA activities by 6.4, 9.1, 10.6, 11.0, 11.2, 12.0, and 18.6%, but decreased PEO, OX and PHO by 6.1, 7.9 and 11.1%, respectively. N fertilization enhanced SOC and TN by 7.6% and 15.3%, respectively, but inhibited MBC by 9.5%. Significant positive correlations were found only between the RRs of C-acq and MBC, suggesting that changes in combined hydrolase activities might act as a proxy for MBC under N fertilization. In contrast with other variables, the RRs of AP, MBC, and TN showed unidirectional trends under different edaphic, environmental, and physiological conditions. Our results provide the first comprehensive set of evidence of how hydrolase and oxidase activities respond to N fertilization in various ecosystems. Future large-scale model projections could incorporate the observed relationship between hydrolases and microbial biomass as a proxy for C acquisition under global N enrichment scenarios in different ecosystems.

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Layered metal oxides have been widely used as the best cathode materials for commercial lithium-ion batteries and are being intensively explored for sodium-ion batteries. However, their application to potassium-ion batteries (PIBs) is hampered because of the poor cycling stability and low rate capability due to the larger ionic size of K than of Li or Na. Herein, a facile self-templated strategy was used to synthesize unique P2-type KCoO microspheres that consist of aggregated primary nanoplates as PIB cathodes. The unique KCoO microspheres with aggregated structure significantly enhanced the kinetics of the K intercalation/deintercation and also minimized the parasitic reactions between the electrolyte and KCoO. The P2-KCoO microspheres demonstrated a high reversible capacity of 82 mAh g at 10 mA g, high rate capability of 65 mAh g at 100 mA g, and long cycle life (87% capacity retention over 300 cycles). The high reversibility of the P2-KCoO full cell paired with a hard carbon anode further demonstrated the feasibility of PIBs. This work not only successfully demonstrates exceptional performance of P2-type KCoO cathodes and microspheres KCoO∥hard carbon full cells, but also provides new insights into the exploration of other layered metal oxides for PIBs.

Low-cost multivalent battery chemistries (Mg , Al ) have been extensively investigated for large-scale energy storage applications. However, their commercialization is plagued by the poor power density and cycle life of cathodes. A universal polyimides@CNT (PI@CNT) cathode is now presented that can reversibly store various cations with different valences (Li , Mg , Al ) at an extremely fast rate. The ion-coordination charge storage mechanism of PI@CNT is systemically investigated. Full cells using PI@CNT cathodes and corresponding metal anodes exhibit long cycle life (>10000 cycles), fast kinetics (>20 C), and wide operating temperature range (-40 to 50 °C), making the low-cost industrial polyimides universal cathodes for different multivalent metal batteries. The stable ion-coordinated mechanism opens a new foundation for the development of high-energy and high-power multivalent batteries.

Nitrogen-induced suppression of lignin-modifying enzyme activity contributes to soil carbon sequestration.

Lithiated silicon significantly increases the Li plating/stripping Coulombic efficiency to a recorded highest value of >99.7% due to successful elimination of the dead Li. The reported principle can be broadly applied to other active materials (such as Sn, Bi, Sb) for other metal anodes including K and Na batteries. The discovery opens up an entirely new avenue for all alkali metal batteries and will attract a broad range of scientists and engineers working on metal anode battery technologies in general.

Potassium-ion batteries have been regarded as the potential alternatives to lithium-ion batteries (LIBs) due to the low cost, earth abundance, and low potential of K (−2.936 vs standard hydrogen electrode (SHE)). However, the lack of low-cost cathodes with high energy density and long cycle life always limits its application. In this work, high-energy layered P2-type hierarchical K 0.65 Fe 0.5 Mn 0.5 O 2 (P2-KFMO) microspheres, assembled by the primary nanoparticles, are fabricated via a modified solvent-thermal method. Benefiting from the unique microspheres with primary nanoparticles, the K + intercalation/deintercalation kinetics of P2-KFMO is greatly enhanced with a stabilized cathodic electrolyte interphase on the cathode. The P2-KFMO microsphere presents a highly reversible potassium storage capacity of 151 mAh g −1 at 20 mA g −1 , fast rate capability of 103 mAh g −1 at 100 mA g −1 , and long cycling stability with 78% capacity retention after 350 cycles. A full cell with P2-KFMO microspheres as cathode and hard carbon as anode is constructed, which exhibits long-term cycling stability (>80% of retention after 100 cycles). The present high-performance P2-KFMO microsphere cathode synthesized using earth-abundant elements provides a new cost-effective alternative to LIBs for large-scale energy storage.The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10. 1002/adfm.201800219. in vain due to the limited and unevenly distributed Li sources. [2] In addition, the rapid expansion of renewable energy market from wind, solar, hydropower, and other intermittent energy sources has also triggered growing demand for high-energy density and low-cost energy storage systems, which further stimulated broad investigation beyond the Li-ion battery technologies. [3][4][5] Among these technologies, sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs) are the two most promising alternatives to LIBs due to the earth-abundance and accessibility of Na and K compared with Li. [3][4][5][6][7][8] Statistically, K and Na elements remarkably occupy 2.09 and 2.3 wt% of the earth's crust (vs 0.0017% of Li) respectively. [3,9] However, since K has lower standard redox potential (−2.936 V vs standard hydrogen electrode (SHE)) than Na (−2.714 V), and is close to Li's potential (−3.040 V), a higher operating voltage, thus a high energy density could be delivered for PIBs, which seems to be a more attractive choice as affordable replacement of LIBs as large-scale energy storage system. [4,6,7] Extensive efforts have been devoted to explore high capacity PIB anode and significant advances have been achieved in high performance anode materials. [10][11][12][13][14][15][16][17][18][19] Among them, the carbonaceous materials (graphite, [10,13,14] hard/soft carbon, [12,13] and graphene [18] ) and metal (antimony, [19] tin [15] ) and metal oxides (K 2 Ti 4 O 9 ) [17] show very promising performance. Different from the wide range of options on anode materials, only a limited number...