The Min River basin, China. In order to investigate the ecohydrological response under historical and future land use changes, we simulated daily runoff sequences under different land use scenarios by coupling the PLUS model with the Physical Hydrological Model and quantitatively assessed the ecohydrological impacts of different land use changes in the watershed by combining the IHA method. The Min River Basin is dominated by grassland, woodland and, cultivated land which account for 94 % of the total. During the period 2000–2020, the area of cultivated land decreased by 4.47 % overall, and construction land increased by 78.68 % overall. Compared to the base year of 2010, the multi-year average monthly runoff increased under different land use scenarios. The high flow indicators (1 daymax, 7 daymax, and 30 daymax) had the largest increasing trend under the natural development scenario in 2030, 54 m3/s, 33 m3/s, and 24 m3/s, respectively, whereas their increase decreased under the ecological protection scenario in 2030; the low flow indicators (1 daymin, 7 daymin, and 30 daymin) decreased less in the 2030 eco-protection scenario than in the natural development scenario, where they decreased by − 5 m3/s, − 9 m3/s, and − 11 m3/s, respectively. The results of the study contribute to a deeper understanding of the response of watershed hydrological processes to land-use change.
Sulfate polysaccharides can inhibit DNA digestion in simulated gastric juice in vitro, which is important for regulating dietary nucleic acids metabolism, but the mechanism of inhibition is unclear. This study used dextran sulfate (DS) with different sulfate groups and molecular weights to explore the effect of DS on DNA digestion. Molecular interactions between DS and DNA were investigated by biolayer interferometry (BLI), isothermal titration calorimetry (ITC) and molecular dynamics simulations. Results indicated that DS with higher molecular weight and sulfate group content showed stronger inhibitory effect of DNA digestion. ITC results showed that the combined Kd value of DNA and DS was about 2.53 mM. The main reason for inhibition of DNA digestion is that the formation of hydrogen bonds between the sulfate group of DS and DNA bases hinders the binding of DNA to pepsin. This finding will facilitate new strategies for nucleic acid metabolism and oral drug delivery.
Fungal cell walls are dynamic extracellular matrices that enable efficient adaptation to changing environments. While the cell wall compositions of yeasts, human, and plant pathogenic fungi have been studied to some extent, the cell walls of mycoparasites remain poorly characterized.
Mixed-linkage (1,3;1,4)-β-glucans, which are widely distributed in cell walls of the grasses, are linear glucose polymers containing predominantly (1,4)-β-linked glucosyl units interspersed with single (1,3)-β-linked glucosyl units. Their distribution in cereal grains and unique structures are important determinants of dietary fibers that are beneficial to human health. We demonstrate that the barley cellulose synthase-like CslF6 enzyme is sufficient to synthesize a high-molecular weight (1,3;1,4)-β-glucan in vitro. Biochemical and cryo-electron microscopy analyses suggest that CslF6 functions as a monomer. A conserved "switch motif" at the entrance of the enzyme's transmembrane channel is critical to generate (1,3)-linkages. There, a single-point mutation markedly reduces (1,3)-linkage formation, resulting in the synthesis of cellulosic polysaccharides. Our results suggest that CslF6 monitors the orientation of the nascent polysaccharide's second or third glucosyl unit. Register-dependent interactions with these glucosyl residues reposition the polymer's terminal glucosyl unit to form either a (1,3)- or (1,4)-β-linkage.
With the development of new concepts and technologies of laparoscopic diagnosis and treatment, inguinal hernia repair is increasingly and widely used in clinical practice, and accordingly, the corresponding complications of deep vein thrombosis have also attracted clinical attention. Deep-venous thrombosis and pulmonary embolism have become one of the potential and very dangerous serious complications in patients with inguinal hernia. One case of sudden pulmonary embolism shortly after the laparoscopic inguinal hernia repair was reported in this paper, the patient has been trapped in a persistent plant survival state after rescue. The patient was a male, 67-year-old patient with up to 4 hours of operation, and no available clinical evidences about operative vascular injury have been found, however, this case have been triggered a civil lawsuit for medical damages and the filing of a judicial expertise. Combined with the disputes of this case and the results of the technical review, the legal related preoperative notification and informed consent, the requirements and functions of working system before operation, the preoperative examination and the related surgical risk-factors of pulmonary embolism are discussed. It is suggests that the preoperative discussion, preoperative examination and preoperative notification of laparoscopic inguinal hernia should be paid great attention to in clinical work, and form an institutionalized and normative workflow, which plays an important role in effectively controlling the operation time, reducing surgical complications and avoiding medical disputes.
Polymer flooding is widely and successfully used to enhance oil recovery. How to further enhance oil recovery after polymer flooding becomes an important question that needs to be solved to stabilize oil production. Branched-preformed particle gel (B-PPG) is a newly developed chemical agent to enhance the oil recovery from heterogeneous reservoirs. Here, laboratory experiments were performed to investigate the enhanced oil recovery of B-PPG/hydrolyzed polyacrylamide (HPAM) mixed solutions through heterogeneous porous media by the core flood test. The results show that the B-PPG/HPAM mixed solutions have a higher oil recovery than solutions containing HPAM or B-PPG alone because of the synergistic effect between B-PPG and HPAM. B-PPG can adjust flows in different permeability zones by its properties of blocking, deforming, and passing through the throat during flow, which can be proved by the fractional flow behaviors in the parallel-sandpack displacement test. HPAM can not only increase the viscosity of the flooding but also enhance the sustained effect of B-PPG. The resistance factors during the flow of B-PPG/HPAM mixed solutions through heterogeneous porous media were also measured. The B-PPG/HPAM mixed solutions have higher resistance factors and residual factors than the solutions of HPAM or B-PPG alone. The relationships between oil recovery and resistance factor show that B-PPG/HPAM mixed solutions have better abilities to enhance oil recovery because of the synergistic effect. Furthermore, the microscopic displacement behaviors in the heterogeneous microscopic model were investigated. The results are consistent with the core flood test and confirm that B-PPG and HPAM have the synergistic effect on further-enhanced oil recovery after polymer flooding.
Liquid chromatography electrospray ionization tandem mass spectrometry (LC/ESI-MS/ MS) and high-performance liquid chromatography (HPLC) methods have been used to identify and quantify the major taxoids from extracts of Taxus chinensis cell cultures. Chromatography was carried out on a reverse phase C18 column with isocratic-mode elution. By analytically comparing LC/ESI-MS/MS of the extracts with that of the available reference substances and literature, six taxoids were identified as taxuyunnanine C (Tc, 1), yunnanxane (2), 2α,5α,10β-triacetoxy-14β-propionyloxytaxa-4(20),11-diene (3), 2α,5α,10β-triacetoxy-14β- (2-methyl)butyryloxytaxa-4(20),11-diene (4), taxol (5), and baccatin III (B III, 6), respectively. Among them, 2, 3 and 4 were assigned in the absence of the corresponding reference substances, and 3 and 4 were detected in this cell line for the first time. The identification was validated by NMR spectra. The precise quantification of 1 and 5 was made using HPLC. The limit of detection (LOD), 0.5 μg/ml for 5, 1.5 μg/ml for 1, and the linearity and accuracy of the quantitative method were evaluated, indicating a wide linear range and satisfactory accuracy. The amounts of other identified taxoids were calculated on the basis of comparison of the absolute response factors of similar structural substances. The proposed method provides a rapid, conventional and reliable tool to characterize and study cell lines for elucidating the taxane biosynthesis.
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