Immediate and legacy effects of snow exclusion on soil fungal diversity and community composition

Background:Soil fungi play crucial roles in ecosystem functions.However,how snow cover change associated with winter warming affects soil fungal communities remains unclear in the Tibetan forest.Methods:We conducted a snow manipulation experiment to explore immediate and legacy effects of snow exclusion on soil fungal community diversity and composition in a spruce forest on the eastern Tibetan Plateau.Soil fungal communities were performed by the high throughput sequencing of gene-fragments.Results:Ascomycota and Basidiomycota were the two dominant fungal phyla and Archaeorhizomyces,Aspergillus and Amanita were the three most common genera across seasons and snow manipulations.Snow exclusion did not affect the diversity and structure of soil fungal community in both snow-covered and snow-free seasons.However,the relative abundance of some fungal communities was different among seasons.Soil fungal groups were correlated with environmental factors(i.e.,temperature and moisture)and soil biochemical variables(i.e.,ammonium and enzyme).Conclusions:These results suggest that the season-driven variations had stronger impacts on soil fungal community than short-term snow cover change.Such findings may have important implications for soil microbial processes in Tibetan forests experiencing significant decreases in snowfall.

Multi-Scale Superhydrophobic Anti-Icing Coating for Wind Turbine Blades

As a surface functional material,super-hydrophobic coating has great application potential in wind turbine blade anti-icing,self-cleaning and drag reduction.In this study,ZnO and SiO2 multi-scale superhydrophobic coatings with mechanical flexibility were prepared by embedding modified ZnO and SiO2 nanoparticles in PDMS.The prepared coating has a higher static water contact angle(CA is 153°)and a lower rolling angle(SA is 3.3°),showing excellent super-hydrophobicity.Because of its excellent superhydrophobic ability and micro-nano structure,the coating has good anti-icing ability.Under the conditions of−10
C and 60%relative humidity,the coating can delay the freezing time by 1511S,which is 10.7 times slower than the normal freezing time.More importantly,due to the mechanical properties provided by SiO2 and the synergistic effect of micro-nano particles,the coating has excellent mechanical durability.After 10 wear tests,the contact angle of the coating is still as high as 141°and the rolling angle is 6.8°.This research provides a theoretical reference for the preparation of a mechanically stable coating with a simple preparation process,as well as a basic research on the anti-icing behavior of the coating.

Chemical profiling of principle active and toxic constituents in herbs containing aristolochic acids

Objective:To clear the amounts of the principal active/toxic components in herbs containing aristolochic acids(HCAAs),which are still used as medicine and/or seasoning in many ethnic minority areas of China.Methods:In this study,six major active and toxic components in HCAAs were extracted with ultrasonic extraction.With 6-O-methyl guanosine as internal standard,the target compounds were analyzed qualitatively and quantitatively by using ultrahigh performance liquid chromatography-electrospray ionization-tandem mass spectrometry(UPLC-ESI-MS/MS)with multiple reaction monitoringinformation dependent acquisition-enhanced production ion scanning mode(MRM-IDA-EPI)combined with dynamic background subtraction(DBS)function.Results:The method showed good linearity in the linear range of the six analytes.The limit range of detection was from 0.01 ng/mL to 0.27 ng/mL.All of the detection repeatability,extraction repeatability and accuracy of the method were good.After extraction,the samples remained stable at 15℃ within 24 h.Six analytes were all found in samples except aristolactam(AL)in sample 2,and the contents varied greatly.The contents of these compounds decreased in fruits,leaves and stems of Aristolochia delavayi successively.Conclusion:This method has the advantages of less sample dosage,simple operation,short analysis cycle,high sensitivity,specificity and accuracy.It laid a good foundation for guiding the safety of HCAAs,the indepth study of pharmacological and toxicological effects and the scientific and standardized processing and compatibility of HCAAs.

Air plasma-sprayed high-entropy (Y_(0.2)Yb_(0.2)Lu_(0.2)Eu_(0.2)Er_(0.2))_(3)Al_(5)O_(12) coating with high thermal protection performance

High-entropy rare-earth aluminate(Y_(0.2)Yb_(0.2)Lu_(0.2)Eu_(0.2)Er_(0.2))_(3)Al_(5)O_(12)(HE-RE_(3)Al_(5)O_(12))has been considered as a promising thermal protection coating(TPC)material based on its low thermal conductivity and close thermal expansion coefficient to that of Al2O3.However,such a coating has not been experimentally prepared,and its thermal protection performance has not been evaluated.To prove the feasibility of utilizing HE-RE_(3)Al_(5)O_(12) as a TPC,HE-RE_(3)Al_(5)O_(12) coating was deposited on a nickelbased superalloy for the first time using the atmospheric plasma spraying technique.The stability,surface,and cross-sectional morphologies,as well as the fracture surface of the HE-RE_(3)Al_(5)O_(12) coating were investigated,and the thermal shock resistance was evaluated using the oxyacetylene flame test.The results show that the HE-RE_(3)Al_(5)O_(12) coating can remain intact after 50 cycles at 1200℃ for 200 s,while the edge peeling phenomenon occurs after 10 cycles at 1400℃ for 200 s.This study clearly demonstrates that HE-RE_(3)Al_(5)O_(12) coating is effective for protecting the nickel-based superalloy,and the atmospheric plasma spraying is a suitable method for preparing this kind of coatings.

Atomic-resolution investigation of structural transformation caused by oxygen vacancy in La_(0.9)Sr_(0.1)TiO_(3+δ)titanate layer perovskite ceramics

Perovskite functional ceramics have been widely applied for thermal protection owing to their unique physical properties.However,formation of oxygen vacancies under external stimuli usually limits their performance in practical applications.Therefore,the mechanism of the effect of oxygen vacancy on the layer structure of perovskite La_(0.9)Sr_(0.1)TiO_(3+δ)was investigated by experiments and first-principles simulations.The experimental results showed that the lattice distortion occurred in oxygen-deficient environment to give a longer c-axis,along with a significant adjustment in the modes of A/B–O bond vibration,resulting in lower reflectivity.Advanced transmission electron microscopy studies revealed that oxygen vacancies induced localized atomic rearrangements via[TiO_(6)]layer movements to adapt to the lattice distortion.This eventually restructured a part of the layer interfaces by expanding the overlapping projection of atoms in the c-axial direction.The specific transformation process was described as a compendious process,while geometric phase analysis effectively clarified how oxygen vacancies can inhibit reflectivity on the layer structure.Thus,this study provides effective approaches for researching the effects of oxygen vacancy on the physical properties of orthorhombic layer perovskite structures,which may facilitate the development of perovskite-based functional devices.

Effects of snow absence on available N pools and enzyme activities within soil aggregates in a spruce forest on the eastern Tibetan Plateau

Winter climate change has great potential to affect the functioning of terrestrial ecosystems.In particular,increased soil frost associated with reduced insulating snow cover may impact the soil nitrogen(N)dynamics in cold ecosystems,but little is known about the variability of these effects among the soil aggregates.A snow manipulation experiment was conducted to investigate the effects of snow absence on N cycling within soil aggregates in a spruce forest on the eastern Tibetan Plateau of China.The extractable soil available N(ammonium and nitrate),net N mineralization rate,and N cycling-related enzyme activities(urease,nitrate reductase,and nitrite reductase)were measured in large macroaggregate(>2 mm),small macroaggregate(0.25–2 mm),and microaggregate(<0.25 mm)during the early thawing period in the years of 2016 and 2017.Snow absence increased soil N availabilities and nitrite reductase activity in microaggregate,but did not affect net N mineralization rate,urease or nitrate reductase activities in any of the aggregate fractions.Regardless of snow manipulations,both soil inorganic N and nitrate reductase were higher in small macroaggregate than in the other two fractions.The effect of aggregate size and sampling year was significant on soil mineral N,net N mineralization rate,and nitrite reductase activity.Our results indicated that snow cover change exerts the largest impact on soil N cycling within microaggregate,and its effect is dependent on winter conditions(e.g.,snow cover and temperature).Such findings have important implications for soil N cycling in snow-covered subalpine forests experiencing pronounced winter climate change.