2,685 research outputs found

    Evidence of Carbon Uptake Associated with Vegetation Greening Trends in Eastern China

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    Persistent and widespread increase of vegetation cover, identified as greening, has been observed in areas of the planet over late 20th century and early 21st century by satellite-derived vegetation indices. It is difficult to verify whether these regions are net carbon sinks or sources by studying vegetation indices alone. In this study, we investigate greening trends in Eastern China (EC) and corresponding trends in atmospheric CO₂ concentrations. We used multiple vegetation indices including NDVI and EVI to characterize changes in vegetation activity over EC from 2003 to 2016. Gap-filled time series of column-averaged CO₂ dry air mole fraction (XCO₂) from January 2003 to May 2016, based on observations from SCIAMACHY, GOSAT, and OCO-2 satellites, were used to calculate XCO₂ changes during growing season for 13 years. We derived a relationship between XCO₂ and surface net CO₂ fluxes from two inversion model simulations, CarbonTracker and Monitoring Atmospheric Composition and Climate (MACC), and used those relationships to estimate the biospheric CO₂ flux enhancement based on satellite observed XCO₂ changes. We observed significant growing period (GP) greening trends in NDVI and EVI related to cropland intensification and forest growth in the region. After removing the influence of large urban center CO₂ emissions, we estimated an enhanced XCO₂ drawdown during the GP of −0.070 to −0.084 ppm yr⁻¹. Increased carbon uptake during the GP was estimated to be 28.41 to 46.04 Tg C, mainly from land management, which could offset about 2–3% of EC’s annual fossil fuel emissions. These results show the potential of using multi-satellite observed XCO₂ to estimate carbon fluxes from the regional biosphere, which could be used to verify natural sinks included as national contributions of greenhouse gas emissions reduction in international climate change agreements like the UNFCC Paris Accord

    Quantum interface between frequency-uncorrelated down-converted entanglement and atomic-ensemble quantum memory

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    Photonic entanglement source and quantum memory are two basic building blocks of linear-optical quantum computation and long-distance quantum communication. In the past decades, intensive researches have been carried out, and remarkable progress, particularly based on the spontaneous parametric down-converted (SPDC) entanglement source and atomic ensembles, has been achieved. Currently, an important task towards scalable quantum information processing (QIP) is to efficiently write and read entanglement generated from a SPDC source into and out of an atomic quantum memory. Here we report the first experimental realization of a quantum interface by building a 5 MHz frequency-uncorrelated SPDC source and reversibly mapping the generated entangled photons into and out of a remote optically thick cold atomic memory using electromagnetically induced transparency. The frequency correlation between the entangled photons is almost fully eliminated with a suitable pump pulse. The storage of a triggered single photon with arbitrary polarization is shown to reach an average fidelity of 92% for 200 ns storage time. Moreover, polarization-entangled photon pairs are prepared, and one of photons is stored in the atomic memory while the other keeps flying. The CHSH Bell's inequality is measured and violation is clearly observed for storage time up to 1 microsecond. This demonstrates the entanglement is stored and survives during the storage. Our work establishes a crucial element to implement scalable all-optical QIP, and thus presents a substantial progress in quantum information science.Comment: 28 pages, 4 figures, 1 tabl

    Hypoglycemic and Hypolipidemic Effects of Ethanolic Extract of Mirabilis jalapa L. Root on Normal and Diabetic Mice

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    The present study investigated the insulin sensitivity, hypoglycemic, and hypolipidemic activities of ethanolic extract of Mirabilis jalapa L. root (EEM) in normal and diabetic mice. After induction of diabetes with streptozotocin, both normal and diabetic mice were singly or repeatedly for 28 days administrated with EEM at doses of 2, 4, 8 g/kg, respectively. Before induction of diabetes, mice were administrated with EEM at doses of 2, 4, 8 g/kg for 14 days and were injected with streptozotocin and continued on EEM administration for another 28 days. Both after and before induction of diabetes, repeated administration with 4, 8 g/kg EEM continually lowered blood glucose level, decreased serum insulin level and improved insulin sensitivity index, and lowered serum total cholesterol, triglyceride levels and triglyceride content in liver and skeletal muscle, and increased glycogen content in these tissues; but repeated administration had no influence on those indexes of normal mice. Single administration with EEM (4, 8 g/kg) showed hypoglycemic effect in oral glucose tolerance test in normal and diabetic mice. Single administration with EEM had no hypoglycemic and hypolipidemic effects on normal and diabetic mice. These results suggest that EEM possesses both potential insulin sensitivity, hypoglycemic, and hypolipidemic effects on diabetes

    Corneal optical density: Structural basis, measurements, influencing factors, and roles in refractive surgery

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    The cornea is the main refractive medium of the human eye, and its clarity is critical to visual acuity. Corneal optical density (COD) is an important index to describe corneal transparency. Intact corneal epithelial and endothelial cells, regular arrangement of collagen fibers in the stroma, and normal substance metabolism are all integral for the cornea to maintain its transparency. In the last two decades, the Pentacam Scheimpflug imaging system has emerged as a breakthrough for the measurement of COD (also called corneal densitometry). It has been found that a wide variety of factors such as age, refractive status, and corneal diseases can affect COD. Different corneal refractive surgery methods also change COD in different corneal regions and layers and affect visual acuity following the surgery. Thus, COD has gradually become a significant indicator to evaluate corneal health, one on which the attention of clinicians has been increasingly focused

    Poly[[hemi-μ4-oxalato-hemi-μ2-oxalato-bis­(μ3-pyrazine-2-carboxyl­ato)erbium(III)silver(I)] monohydrate]

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    The asymmetric unit of the title complex, {[AgEr(C5H3N2O2)2(C2O4)]·H2O}n, contains one ErIII atom, one AgI atom, two pyrazine-2-carboxyl­ate (pyc) ligands, two half oxalate ligands (each lying on an inversion center) and one uncoordinated water mol­ecule. The ErIII atom is coordinated by two O atoms and two N atoms from two pyc ligands, one O atom from a third pyc ligand and four O atoms from two oxalate ligands in a distorted monocapped square-anti­prismatic geometry. The AgI atom is coordinated by two N atoms from two pyc ligands, one O atom from a third pyc ligand and one O atom from one oxalate ligand. The crystal structure exhibits a three-dimensional heterometallic polymeric network. O—H⋯O hydrogen bonding between the uncoordinated water mol­ecule and carboxyl­ate O atoms is observed

    A Novel Postbiotic From Lactobacillus rhamnosus GG With a Beneficial Effect on Intestinal Barrier Function

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    It has long been known that probiotics can be used to maintain intestinal homeostasis and treat a number of gastrointestinal disorders, but the underlying mechanism has remained obscure. Recently, increasing evidence supports the notion that certain probiotic-derived components, such as bacteriocins, lipoteichoic acids, surface layer protein and secreted protein, have a similar protective role on intestinal barrier function as that of live probiotics. These bioactive components have been named ‘postbiotics’ in the most recent publications. We previously found that the Lactobacillus rhamnosus GG (LGG) culture supernatant is able to accelerate the maturation of neonatal intestinal defense and prevent neonatal rats from oral Escherichia coli K1 infection. However, the identity of the bioactive constituents has not yet been determined. In this study, using liquid chromatography-tandem mass spectrometry analysis, we identified a novel secreted protein (named HM0539 here) involved in the beneficial effect of LGG culture supernatant. HM0539 was recombinated, purified, and applied for exploring its potential bioactivity in vitro and in vivo. Our results showed that HM0539 exhibits a potent protective effect on the intestinal barrier, as reflected by enhancing intestinal mucin expression and preventing against lipopolysaccharide (LPS)- or tumor necrosis factor α (TNF-α)-induced intestinal barrier injury, including downregulation of intestinal mucin (MUC2), zonula occludens-1 (ZO-1) and disruption of the intestinal integrity. Using a neonatal rat model of E. coli K1 infection via the oral route, we verified that HM0539 is sufficient to promote development of neonatal intestinal defense and prevent against E. coli K1 pathogenesis. Moreover, we further extended the role of HM0539 and found it has potential to prevent dextran sulfate sodium (DSS)-induced colitis as well as LPS/D-galactosamine-induced bacterial translocation and liver injury. In conclusion, we identified a novel LGG postbiotic HM0539 which exerts a protective effect on intestinal barrier function. Our findings indicated that HM0539 has potential to become a useful agent for prevention and treatment of intestinal barrier dysfunction- related diseases

    MicroRNA-203 inhibits cell proliferation by repressing ΔNp63 expression in human esophageal squamous cell carcinoma

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    <p>Abstract</p> <p>Background</p> <p>This study was performed to investigate the effect of microRNA-203 (miR-203) and ΔNp63 on cell proliferation and the functional connection between miR-203 and ΔNp63 in ESCC.</p> <p>Methods</p> <p>We employed 2 human ESCC cell lines, Eca109 and TE-1, as the model system. The effect of miR-203 and ΔNp63 on cell proliferation was determined in cells transfected with miR-203 mimic and ΔNp63 small interfering RNA (siRNA), respectively. The regulation of ΔNp63 expression in ESCC cells by miR-203 was studied by luciferase reporter assay, RT-PCR and western blot analysis in cells transfected with miR-203. The effect of ΔNp63 re-expression on miR-203 induced inhibition of cell proliferation was studied by cell proliferation assay in cells cotransfected with miR-203 and pcDNA-ΔNp63 plasmid (without the 3'-UTR of <it>ΔNp63</it>).</p> <p>Results</p> <p>We found that both miR-203 and ΔNp63 siRNA signicantly inhibited cell proliferation in ESCC. MiR-203 could down-regulate endogenous ΔNp63 expression at the posttranscriptional level. Moreover, re-expression of ΔNp63 in cells transfected with miR-203 significantly attenuated the miR-203 induced inhibition of cell proliferation.</p> <p>Conclusions</p> <p>Our data implied that miR-203 could inhibit cell proliferation in human ESCC through ΔNp63-mediated signal pathway. Therefore, we propose that miR-203 might be used as a therapeutic agent for human ESCC.</p
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