648 research outputs found

    Spatial distribution of the persistent organic pollutants across the Tibetan Plateau and its linkage with the climate systems: a 5-year air monitoring study

    Get PDF
    The Tibetan Plateau (TP) has been contaminated by persistent organic pollutants (POPs), including legacy organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) through atmospheric transport. The exact source regions, transport pathways and time trends of POPs to the TP are not well understood. Here polystyrene–divinylbenzene copolymer resin (XAD)-based passive air samplers (PASs) were deployed at 16 Tibetan background sites from 2007 to 2012 to gain further insight into spatial patterns and temporal trends of OCPs and PCBs. The southeastern TP was characterized by dichlorodiphenyltrichloroethane (DDT)-related chemicals delivered by Indian monsoon air masses. The northern and northwestern TP displayed the greatest absolute concentration and relative abundance of hexachlorobenzene (HCB) in the atmosphere, caused by the westerly-driven European air masses. The interactions between the DDT polluted Indian monsoon air and the clean westerly winds formed a transition zone in central Tibet, where both DDT and HCB were the dominant chemicals. Based on 5 years of continuous sampling, our data indicated declining concentrations of HCB and hexachlorocyclohexanes (HCHs) across the Tibetan region. Inter-annual trends of DDT class chemicals, however, showed less variation during this 5-year sampling period, which may be due to the ongoing usage of DDT in India. This paper demonstrates the possibility of using POP fingerprints to investigate the climate interactions and the validity of using PAS to derive inter-annual atmospheric POP time trends

    Effect of HNO3 treatment on the La0.6Sr0.4Co0.2Fe0.8O3-delta obtained via combined EDTA-citrate complexing process

    Get PDF
    The La0.6Sr0.4Co0.2Fe0.8O3-delta(LSCF) composite oxide was prepared via combined EDTA-citrate complexing process with concentrated nitric acid treatment. The treatment would result in the self-combustion of solid state precursors at low temperatures. The effect of preparing conditions on LSCF's catalytic properties was investigated by using decomposition of peroxide hydrogen as the model. The FT-IR results of the solid state precursor and the pH values of aqueous solution of it were studied to determine the mechanism of the thermal decomposition of organic in the precursor and of the self-combustion process. Moreover, XRD was employed to characterize the crystal structure of LSCF calcined at higher temperatures. The study shows that the treatment can depress the growth of crystallite and improve the catalysis for decomposition of peroxide hydrogen. Of the all samples, the LSCF-40-900 has the highest activity to the decomposition of peroxide hydrogen

    Visualizing the elongated vortices in γ\gamma-Ga nanostrips

    Get PDF
    We study the magnetic response of superconducting γ\gamma-Ga via low temperature scanning tunneling microscopy and spectroscopy. The magnetic vortex cores rely substantially on the Ga geometry, and exhibit an unexpectedly-large axial elongation with aspect ratio up to 40 in rectangular Ga nano-strips (width ll << 100 nm). This is in stark contrast with the isotropic circular vortex core in a larger round-shaped Ga island. We suggest that the unusual elongated vortices in Ga nanostrips originate from geometric confinement effect probably via the strong repulsive interaction between the vortices and Meissner screening currents at the sample edge. Our finding provides novel conceptual insights into the geometrical confinement effect on magnetic vortices and forms the basis for the technological applications of superconductors.Comment: published in Phys. Rev. B as a Rapid Communicatio

    Food for special medical purpose for cancer patients and related nutrition research progress

    Get PDF
    This review outlined the regulatory policy and approval progress of food for the special medical purpose (FSMP), analyzed the development status and the development key point of cancer FSMP. And the recent nutrition research related to cancer FSMP was reviewed

    Rescue of mesangial cells from high glucoseinduced over-proliferation and extracellular matrix secretion by hydrogen sulfide

    Get PDF
    Abstract Background. Hydrogen sulfide (H 2 S) is considered as the third gasotransmitter after nitric oxide and carbon monoxide. This gas molecule participates in the regulation of renal function. Diabetic nephropathy (DN) is one of the major chronic complications of diabetes. The present study aimed to explore the changes in H 2 S metabolism in the early stage of DN and the effects of H 2 S on cultured rat renal glomerular mesangial cells (MCs). Methods. Cultured rat MCs and streptozotocin (STZ)-induced diabetic rats were used in this study. Expression levels of cystathionine γ-lyase (CSE), transforming growth factor-β1 (TGF-β1) and collagen IV in rat renal cortex and in cultured MCs were determined by quantitative real-time PCR and western blot. Reactive oxygen species (ROS) released from rat MCs was assessed by fluorescent probe assays. MCs proliferation was analyzed by 5′-bromo-2′-deoxyuridine incorporation assay. Results. H 2 S levels in the plasma and renal cortex and the levels of CSE messenger RNA (mRNA) and protein in renal cortex were significantly reduced, while the levels of TGF-β1 and collagen IV increased 3 weeks after STZ injection. Administration of NaHS, a H 2 S donor, reversed the increases in TGF-β1 and collagen IV in diabetic rats. By contrast, NaHS did not alter the TGF-β1 and collagen IV levels in non-diabetic rats. But NaHS lowered the CSE mRNA level in renal cortex. Exposure to high glucose promoted ROS generation and cell proliferation, up-regulated the expression of TGF-β1 and collagen IV but decreased the CSE expression in cultured MCs. Treatment of cultured MCs with NaHS reversed the effect of high glucose. NaHS did not change ROS generation, cell proliferation, TGF-β1 and collagen IV expression in the cells cultured with normal glucose. Reduction of endogenous H 2 S generation by DLpropargylglycine, a CSE inhibitor, produced similar cellular effects as high glucose, including increases in cell proliferation, TGF-β1 and collagen IV expressions and ROS generation. Conclusion. Suppressed CSE-catalyzed endogenous H 2 S production in the kidney by hyperglycemia may play an important role in the pathogenesis of DN

    Construction of Shanghai Diabetes Clinical Database and real-world study

    Get PDF
    Objective·To construct a clinical database of diabetes in Shanghai, mine the value of clinical data, and carry out real-world study.Methods·The data were extracted from Shanghai Link Healthcare Database. All original clinical data have undergone standard processes such as desensitization, encryption, cleaning, standardization, information extraction and structuring, and clinical data were analyzed by the method of medical statistics or machine learning according to different research contents.Results·The database has imported the clinical data of 150 million visits and treatment records of 2.12 million diabetic patients in 37 municipal hospitals over a ten-year period from 2013 to 2022. The overall analysis showed the basic characteristics and development trends of all aspects of diabetes disease in real-world settings, the potential risks of diabetes are discovered by constructing retrospective cohort, and the inherent patterns of the disease are revealed by using machine learning methods such as cluster analysis and network analysis.Conclusion·The establishment of Shanghai Diabetes Clinical Database can not only summarize and show the clinical status of diabetes, but also obtain more scientific achievements with realistic clinical value by real-world clinical data study

    The LAMOST Survey of Background Quasars in the Vicinity of the Andromeda and Triangulum Galaxies -- II. Results from the Commissioning Observations and the Pilot Surveys

    Full text link
    We present new quasars discovered in the vicinity of the Andromeda and Triangulum galaxies with the LAMOST during the 2010 and 2011 observational seasons. Quasar candidates are selected based on the available SDSS, KPNO 4 m telescope, XSTPS optical, and WISE near infrared photometric data. We present 509 new quasars discovered in a stripe of ~135 sq. deg from M31 to M33 along the Giant Stellar Stream in the 2011 pilot survey datasets, and also 17 new quasars discovered in an area of ~100 sq. deg that covers the central region and the southeastern halo of M31 in the 2010 commissioning datasets. These 526 new quasars have i magnitudes ranging from 15.5 to 20.0, redshifts from 0.1 to 3.2. They represent a significant increase of the number of identified quasars in the vicinity of M31 and M33. There are now 26, 62 and 139 known quasars in this region of the sky with i magnitudes brighter than 17.0, 17.5 and 18.0 respectively, of which 5, 20 and 75 are newly-discovered. These bright quasars provide an invaluable collection with which to probe the kinematics and chemistry of the ISM/IGM in the Local Group of galaxies. A total of 93 quasars are now known with locations within 2.5 deg of M31, of which 73 are newly discovered. Tens of quasars are now known to be located behind the Giant Stellar Stream, and hundreds behind the extended halo and its associated substructures of M31. The much enlarged sample of known quasars in the vicinity of M31 and M33 can potentially be utilized to construct a perfect astrometric reference frame to measure the minute PMs of M31 and M33, along with the PMs of substructures associated with the Local Group of galaxies. Those PMs are some of the most fundamental properties of the Local Group.Comment: 26 pages, 6 figures, AJ accepte

    A simulation study on the measurement of D0-D0bar mixing parameter y at BES-III

    Full text link
    We established a method on measuring the \dzdzb mixing parameter yy for BESIII experiment at the BEPCII e+e−e^+e^- collider. In this method, the doubly tagged ψ(3770)→D0D0‾\psi(3770) \to D^0 \overline{D^0} events, with one DD decays to CP-eigenstates and the other DD decays semileptonically, are used to reconstruct the signals. Since this analysis requires good e/πe/\pi separation, a likelihood approach, which combines the dE/dxdE/dx, time of flight and the electromagnetic shower detectors information, is used for particle identification. We estimate the sensitivity of the measurement of yy to be 0.007 based on a 20fb−120fb^{-1} fully simulated MC sample.Comment: 6 pages, 7 figure
    • …
    corecore