ANN-Based Estimation of Low-Latitude Monthly Ocean Latent Heat Flux by Ensemble Satellite and Reanalysis Products.

Ocean latent heat flux (LHF) is an essential variable for air-sea interactions, which establishes the link between energy balance, water and carbon cycle. The low-latitude ocean is the main heat source of the global ocean and has a great influence on global climate change and energy transmission. Thus, an accuracy estimation of high-resolution ocean LHF over low-latitude area is vital to the understanding of energy and water cycle, and it remains a challenge. To reduce the uncertainties of individual LHF products over low-latitude areas, four machine learning (ML) methods (Artificial Neutral Network (ANN), Random forest (RF), Bayesian Ridge regression and Random Sample Consensus (RANSAC) regression) were applied to estimate low-latitude monthly ocean LHF by using two satellite products (JOFURO-3 and GSSTF-3) and two reanalysis products (MERRA-2 and ERA-I). We validated the estimated ocean LHF using 115 widely distributed buoy sites from three buoy site arrays (TAO, PIRATA and RAMA). The validation results demonstrate that the performance of LHF estimations derived from the ML methods (including ANN, RF, BR and RANSAC) were significantly better than individual LHF products, indicated by R2 increasing by 3.7-46.4%. Among them, the LHF estimation using the ANN method increased the R2 of the four-individual ocean LHF products (ranging from 0.56 to 0.79) to 0.88 and decreased the RMSE (ranging from 19.1 to 37.5) to 11 W m-2. Compared to three other ML methods (RF, BR and RANSAC), ANN method exhibited the best performance according to the validation results. The results of relative uncertainty analysis using the triangle cornered hat (TCH) method show that the ensemble LHF product using ML methods has lower relative uncertainty than individual LHF product in most area. The ANN was employed to implement the mapping of annual average ocean LHF over low-latitude at a spatial resolution of 0.25° during 2003-2007. The ocean LHF fusion products estimated from ANN methods were 10-30 W m-2 lower than those of the four original ocean products (MERRA-2, JOFURO-3, ERA-I and GSSTF-3) and were more similar to observations.

Estimation of Daily Terrestrial Latent Heat Flux with High Spatial Resolution from MODIS and Chinese GF-1 Data.

Reliable estimates of terrestrial latent heat flux (LE) at high spatial and temporal resolutions are of vital importance for energy balance and water resource management. However, currently available LE products derived from satellite data generally have high revisit frequency or fine spatial resolution. In this study, we explored the feasibility of the high spatiotemporal resolution LE fusion framework to take advantage of the Moderate Resolution Imaging Spectroradiometer (MODIS) and Chinese GaoFen-1 Wide Field View (GF-1 WFV) data. In particular, three-fold fusion schemes based on Enhanced Spatial and Temporal Adaptive Reflectance Fusion Model (ESTARFM) were employed, including fusion of surface reflectance (Scheme 1), vegetation indices (Scheme 2) and high order LE products (Scheme 3). Our results showed that the fusion of vegetation indices and further computing LE (Scheme 2) achieved better accuracy and captured more detailed information of terrestrial LE, where the determination coefficient (R2) varies from 0.86 to 0.98, the root-mean-square error (RMSE) ranges from 1.25 to 9.77 W/m2 and the relative RSME (rRMSE) varies from 2% to 23%. The time series of merged LE in 2017 using the optimal Scheme 2 also showed a relatively good agreement with eddy covariance (EC) measurements and MODIS LE products. The fusion approach provides spatiotemporal continuous LE estimates and also reduces the uncertainties in LE estimation, with an increment in R2 by 0.06 and a decrease in RMSE by 23.4% on average. The proposed high spatiotemporal resolution LE estimation framework using multi-source data showed great promise in monitoring LE variation at field scale, and may have value in planning irrigation schemes and providing water management decisions over agroecosystems.

Romboutsia lituseburensis JCM1404 supplementation ameliorated endothelial function via gut microbiota modulation and lipid metabolisms alterations in obese rats.

Our previous study revealed moderate-intensity exercise improved endothelial function associated with decreasing Romboutsia in rats on a high-fat diet. However, whether Romboutsia influences endothelial function remains unclear. The aim of this study was to determine the effects of Romboutsia lituseburensis JCM1404 on the vascular endothelium of rats under standard diet (SD) or high-fat diet (HFD). Romboutsia lituseburensis JCM1404 had a better improvement effect on endothelial function under HFD groups, while no significant effect on small-intestinal and blood vessel morphology. HFD significantly decreased villus height of small intestine and increased outer diameter and media thickness of the vascular tissue. After the treatments by R. lituseburensis JCM1404, the expression of claudin5 was increased in the HFD groups. Romboutsia lituseburensis JCM1404 was found to increase alpha diversity in the SD groups, with an increase in beta diversity in the HFD groups. The relative abundance of Romboutsia and Clostridium_sensu_stricto_1 was decreased significantly in both diet groups after R. lituseburensis JCM1404 intervention. The functions of human diseases and endocrine and metabolic diseases significantly downregulated in the HFD groups by Tax4Fun analysis. Furthermore, we found Romboutsia was significantly associated with bile acids, triglycerides, amino acids and derivatives and organic acids and derivatives in the SD groups, while Romboutsia was significantly associated with triglycerides and free fatty acid in the HFD groups. Romboutsia lituseburensis JCM1404 significantly upregulated several metabolism-related pathways by KEGG analysis in the HFD groups, including glycerolipid metabolism, cholesterol metabolism, regulation of lipolysis in adipocytes, insulin resistance, fat digestion and absorption, thermogenesis. Overall, R. lituseburensis JCM1404 supplementation ameliorated endothelial function via gut microbiota modulation and lipid metabolisms alterations in obese rats.

Simultaneous determination of eight bioactive compounds by LC-MS/MS and its application to the pharmacokinetics, liver first-pass effect, liver and brain distribution of orally administrated Gouteng-Baitouweng (GB) in rats.

Only focusing on the circulating levels is insufficient for the comprehensive understanding of the physiological disposition of herbal medicine in vivo. Therefore, we conducted the comprehensive investigation on the in vivo dynamic process of orally administrated Gouteng-Baitouweng (GB), a classical herb pair with anti-Parkinson potentials. Serving as the technical base, a sensitive and selective liquid chromatography-tandem mass spectrometry method was established and validated in the plasma, liver and brain, for simultaneous determination of five alkaloids (rhynchophylline, isorhynchophylline, corynoxeine, isocorynoxeine and geissoschizine methyl ether) and three saponins (anemoside B4, anemoside A3 and 23-hydroxybetulinic acid). Following liquid-liquid extraction, favorable chromatographic behaviors of eight analytes were obtained on Waters Xbrigde C18 column within 13 min. This method elicited good linearity for the analytes at the concentration range of 0.3-1000 or 1.8-6000 ng/mL with favorable precision, accuracy and stability. Following oral administration of GB (25 g/kg) in rats, this method was applied to the quantitative analysis in the portal vein plasma, liver, systemic plasma, and brain. Consequently, anemoside B4 was of the highest exposure, followed by 23-hydroxybetulinic acid, anemoside A3, rhynchophylline and isocorynoxeine in vivo. Notably, three saponins were all observed with certain exposure in the brain, along with rhynchophylline at low levels. Besides, five alkaloids and 23-hydroxybetulinic acid underwent serious liver first-pass effect. Hence, the pharmacokinetics, liver first-pass effect, liver and brain distribution of ingredients in GB were clarified, which laid a solid foundation for interpreting its efficacy and safety.