Isolation and identification of two galangin metabolites from rat urine and determination of their in vitro hypolipidemic activity

Purpose: To investigate the lipid-lowering activity of two metabolites of galangin, namely, galangin-3-O-β-D-glucuronic acid (GG-1) and galangin-7-O-β-D-glucuronic acid (GG-2).Methods: Female Sprague-Dawley rats were orally administered with galangin. The two metabolites of galangin were isolated from urine sample and purified using Sephadex LH-20 and semi-preparative high performance liquid chromatography (HPLC). The structures of the metabolites were identified by analyzing spectroscopic data. Hypolipidemic activity was evaluated in HepG2 cells. The down- or upregulation of lipogenic genes was detected using real-time quantitative polymerase chain reaction (qPCR).Results: Both metabolites of galangin showed hypolipidemic activity. These  activities are closely associated with the down-regulation of lipogenic genes such as SREBP-1a, SREBP-1c, and SREBP-2 transcription factors, and the downstream genes such as FAS, ACC, and HMGR were revealed by realtime qPCR data.Conclusion: The results show that both metabolites possess better lipid-lowering activities than galangin. These hypolipidemic activities are closely associated with inhibiting key genes or proteins that regulated the biosynthesis of both cholesterol and triglycerides.Keywords: Galangin, Galangin-3-O-β-D-glucuronic acid, Galangin-7-O-β- D-glucuronic acid, Hypolipidemic, Lipogenic genes, Metabolite

Quantification of the Adjacency Effect on Measurements in the Thermal Infrared Region

International audienceSensor-observed energy from adjacent pixels, known as the adjacency effect, influences land surface reflectivity retrieval accuracy in optical remote sensing. As the spatial resolution of thermal infrared (TIR) images increases, the adjacency effect may influence land surface temperature (LST) retrieval accuracy in TIR remote sensing. However, to our knowledge, few studies have focused on quantifying this adjacency effect on TIR measurements. In this study, a forward adjacency effect radiative transfer model (FAERTM) was developed to quantify the adjacency effect on high-spatial-resolution TIR measurements. The model was verified to be in good agreement with moderate resolution atmospheric transmission (MODTRAN) code, with a discrepancy 3 K in some cases. These findings indicate that the adjacency effect should be considered when retrieving LSTs from TIR measurements, at least in some specific conditions. The proposed FAERTM provides a useful model for quantifying and addressing the adjacency effect on TIR measurements

A new thermal infrared channel configuration for accurate land surface temperature retrieval from satellite data

International audienc

A self-adaptive wildfire detection algorithm by fusing physical and deep learning schemes

Currently, the spectra-based physical models and deep learning methods are frequently used to detect wildfires from remote sensing data. However, physical algorithms mainly rely on radiative transfer processes, which limit their effectiveness in detecting small and weak fires. On the other hand, deep learning methods usually lack mechanism constraints, thus generally resulting in false alarms of bright surfaces. It is promising to combine the advantages of them and correspondingly reduce the inherent error of a single algorithm. To this end, in this paper, both the local contextual and the global index method based on physical mechanisms are optimized, simultaneously, a new U-Net model is also establish to accurately detect fires. Moreover, YOLO v5 is incorporated for the first time to extract and remove the false alarms of objects with high exposure. Based on the above series of novel works, a self-adaptive fusing algorithm is finally proposed. Our results reveal that: (1) Short-wave infrared band of about 2.15 μm is crucial in fire detection for data with moderate-to-high resolutions. Taking Landsat 8 as an example, the band combinations of 7, 6, 2(SWIR + VI), 7, 6, 5(SWIR + NIR), and 7, 5, 3(SWIR + VI + NIR) show reasonable accuracy, with recall rate of greater than 81 %. The thermal infrared band can be used to assist in detecting the general location of the fire and serve as alternative choice in extreme cases. (2) The optimized physical algorithm can reduce false alarms and predict more accurate fire positions. (3) It is very effective to introduce the YOLO v5 framework to remove false alarms with high exposure in urban and suburban regions. (4) The proposed self-adaptive fusion algorithm integrates the advantages of various schemes, proving its better performance in terms of robustness, stability and generality compared to any single method. Even in extreme situations such as the Gobi Desert, thin cloud edges, and mountain shadow areas, the fusion algorithm still works well. The generality tests based on Sentinel-2A, WorldView-3, and SPOT-4 reveal the potential applicability of the newly proposed fusing algorithm, especially for data with fine spatial and spectral resolutions

Proteomic analysis of blue light-induced twining response in Cuscuta australis

The parasitic plant Cuscuta australis (dodder) invades a variety of species by entwining the stem and leaves of a host and developing haustoria. The twining response prior to haustoria formation is regarded as the first sign for dodders to parasitize host plants, and thus has been the focus of studies on the host-parasite interaction. However, the molecular mechanism is still poorly understood. In the present work, we have investigated the different effects of blue and white light on the twining response, and identified a set of proteins that were differentially expressed in dodder seedlings using a proteomic approach. Approximately 1,800 protein spots were detected on each 2-D gel, and 47 spots with increased or decreased protein levels were selected and analyzed with MALDI-TOF-MS. Peptide mass fingerprints (PMFs) obtained for these spots were used for protein identification through cross-species database searches. The results suggest that the blue light-induced twining response in dodder seedlings may be mediated by proteins involved in light signal transduction, cell wall degradation, cell structure, and metabolism

Effect of memory behavior on electric-field-induced phase transition and electrocaloric response in antiferroelectric ceramics

Field-induced phase transition in antiferroelectric (AFE) materials always facilitates giant positive/negative electrocaloric (EC) responses for a promising cooling application, while it is not only associated with external field conditions but also applied field history, i.e., memory behavior. Herein, we demonstrate that memory behavior increases the likelihood of observing an EC response when the operating field is parallel to the pre-poling field, as compared to the antiparallel condition. Additionally, when the temperature is slightly above the AFE-ferroelectric (FE) phase transition temperature, the field-off process induces a two-step microstructure change, characterized by a rapid domain rotation followed by a slow phase transition, which finally produces an abnormal EC heat flow signal. Through a Landau theory analysis, this kinetic behavior is contributed to the competition between the ferroelectric (FE) order pinned by memory behavior and the thermal agitation favored AFE state. This work deepens the understanding of the phase transition in the ferroelectric system

Large electrocaloric effect over a wide temperature span in lead-free bismuth sodium titanate-based relaxor ferroelectrics

For efficient solid-state refrigeration technologies based on electrocaloric effect (ECE), it is a great challenge of simultaneously obtaining a large adiabatic temperature change (ΔT) within a wide temperature span (Tspan) in lead-free ferroelectric ceramics. Here, we studied the electrocaloric effect (ECE) in (1-x)(Na0.5Bi0.5)TiO3-xCaTiO3 ((1-x)NBT-xCT) and explored the combining effect of morphotropic phase boundary (MPB) and relaxor feature. The addition of CT not only constructs a MPB region with the coexistence of rhombohedral and orthorhombic phases, but also enhances the relaxor feature. The ECE peak appears around the freezing temperature (Tf), and shifts toward to lower temperature with the increasing CT amount. The directly measured ECE result shows that the ceramic of x = 0.10, which is in the MPB region, has an optimal ECE property of ΔTmax = 1.28 K @ 60 °C under 60 kV/cm with a wide Tspan of 65 °C. The enhanced ECE originates from the electric-field-induced transition between more types of polar nanoregions and long-range ferroelectric macrodomains. For the composition with more relaxor feature in the MPB region, such as x = 0.12, the ECE is relatively weak under low electric fields but it exhibits a sharp increment under a sufficiently high electric field. This work provides a guideline to develop the solid–state cooling devices for electronic components