Evapotranspiration (ET) plays an important role in the hydrological cycle of river basins. Studying ET in the Yellow River Basin (YRB) is greatly significant for the scientific management of water resources. Here, we made full use of the advantages of the Gravity Recovery and Climate Experiment (GRACE) and GRACE Follow-On (GRACE-FO) gravity satellites for monitoring large-scale hydrological changes to calculate the terrestrial water storage anomaly (TWSA) and terrestrial water flux in the YRB from May 2002 to June 2020. Furthermore, combined with terrestrial water flux, precipitation, and runoff data, ET in the YRB was calculated based on the water budget equation and then compared with other traditional ET products. The mutation of annual mean ET was identified by the Mann–Kendall trend test method, and the seasonal and interannual variations of ET were explored. ET was closely related to precipitation. Annual mean ET exhibited a sudden change in 2011, with an insignificant downward trend from 2003 to 2010, followed by an increasing trend from 2011 to 2019, particularly after 2016. Compared with the traditional ET monitoring methods and products, the ET estimated by GRACE/GRACE-FO observations provides a new way to effectively obtain continuous and reliable ET data in a wide range of river basins.
Matrix-assisted
laser desorption/ionization mass spectrometry imaging
(MALDI MSI) is widely applied in mapping macrobiomolecules in tissues,
but it is still limited in profiling low-molecular-weight (MW) compounds
(typically metabolites) due to ion interference and suppression by
organic matrices. Here, we present a versatile “top-down”
strategy for rational engineering of carbon material-based matrices,
by which heteroatom-doped graphene quantum dots (HGQDs) were manufactured
for LDI MS detection and imaging of small biomolecules. The HGQDs
derived from parent materials inherited the π-conjugated networks
and doping sites for promoting energy transfer and negative ion generation,
while their extremely small size guaranteed the matrix uniformity
and signal reproducibility in LDI MSI. Compared to other HGQDs, nitrogen-doped
graphene quantum dots (NGQDs) exhibited superior capability of assisting
LDI
of various small molecules, including amino acids, fatty acids, saccharides,
small peptides, nucleobases, anticancer drugs, and bisphenol pollutants.
Density functional theory simulations also corroborated that the LDI
efficiency was markedly raised by the proton-capturing pyridinic nitrogen
species and compromised by the electron-deficient boron dopants. NGQDs-assisted
LDI MS further enabled label-free investigation on enzyme kinetics
using an ordinary short peptide as the substrate. Moreover, due to
the high salt tolerance and signal reproducibility, the proposed negative-ion
NGQDs-assisted LDI MSI was able to reveal the abundance and distribution
of low-MW species in rat brain tissue and achieved the imaging of
low-MW lipids in coronally sectioned rat brains subjected to traumatic
brain injury. Our work offers a new route for customizing nanomaterial
matrices toward LDI MSI of small biomolecules in biomedical and pathological
research.
We report a DNA origami cipher disk (DOCD) allowing random, continuous and reversible switchover between six visibly different patterns in response to the input DNA strands. A DOCD-enabled tandem-in-time cryptographic...
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