50 research outputs found

    Evaluation of Early Prognostic Factors of Mortality in Patients with Acute Pancreatitis: A Retrospective Study

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    Early and accurate assessment of severity in acute pancreatitis (AP) is of great importance to provide effective disease management and prevent mortality. In this study, we aim to evaluate early indicators that predict the mortality of AP. We retrospectively analyzed 24-hour clinical characteristics and laboratory data in 166 AP patients recruited between January 2014 and November 2015 in Baotou Central Hospital. In total, 18 patients did not survive the disease. Multivariate logistic regression showed that red cell distribution (RDW) (OR = 2.965, P=0.001) and creatinine (OR = 1.025, P=0.005) were early independent risk factors of AP mortality while albumin (OR = 0.920, P=0.032) levels reduced AP mortality. The corresponding optimal cut-off values were 14.45, 125.5, and 34.95, respectively. The positive predictive values of the AP mortality were 80.1%, 54.5%, and 69.5%. In combined measurement, the area under the curve of RDW, creatinine, and albumin was 0.964 (95% CI: 0.924 to 1.000, P<0.001). RDW ≥ 14.45%, creatinine ≥ 125.5 μmol/l, and albumin ≤ 34.95 g/l indicated a good predictive value for mortality in AP patients with a sensitivity of 100% and specificity of 64.2%. RDW, creatinine, and albumin may serve as early indicators for AP mortality which warrants further clinical investigation

    Facile synthesis of monodisperse Cu3SbSe4 nanoparticles and thermoelectric performance of Cu3SbSe4 nanoparticle-based materials

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    International audienceIn this study, large-scale synthesis of Cu3SbSe4 and Cu3Sb0.98Sn0.02Se4 nanoparticles with a narrow size distribution was achieved through a rapid-injection route. These nanoparticles showed a monodisperse and quasi-spherical morphology. The Cu3SbSe4 and Cu3Sb0.98Sn0.02Se4 nanoparticle-based bulk materials were then prepared by hot-pressed sinter of the nanoparticles, and their thermoelectric performances were systematically studied. Due to the reduced lattice thermal conductivity from enhanced phonon scattering at the grain interfaces of the bulk materials, the maximum ZT value of the Cu3Sb0.98Sn0.02Se4 bulk materials reached 0.50 at 575

    Spectroscopic properties of Er3+ and Yb3+ co-doped glass ceramics containing SrF2 nanocrystals

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    International audienceThe spectroscopic properties of Er3+/Yb3+ co-doped 50SiO2-10Al2O3-20ZnF2-20SrF2 glass and glass ceramic containing SrF2 nanocrystals were investigated. The formation of SrF2 nanocrystals in the glass ceramic was confirmed by XRD. The oscillator strengths for several transitions of the Er3+ ions in the glass ceramic have been obtained and the Judd-Ofelt parameters were then determined. The XRD result and Judd-Ofelt parameters suggested that Er3+ and Yb3+ ions had efficiently enriched in the SrF2 nanocrystals in the glass ceramic. The lifetime of excited states has been used to reveal the surroundings of luminescent Er3+ and Yb3+ and energy transfer (ET) mechanism between Er3+ and Yb3+. Much stronger upconversion luminescence and longer lifetime of the Er3+/Yb3+ co-doped glass ceramic were observed in comparison with the Er3+/Yb3+ co-doped glass, which could be ascribed to more efficient ET from Yb3+ to Er3+ due to the enrichment of Yb3+ and Er3+ and the shortening of the distance between lanthanide ions in the precipitated SrF2 nanocrystals

    Near-infrared emission of Yb3+ through energy transfer from ZnO to Yb3+ in glass ceramic containing ZnO nanocrystals.

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    International audienceYb(3+)-doped glass and glass ceramic containing ZnO nanocrystals were prepared by the melting-quenching method and subsequent heat treatment. Intense near-IR emission around 1000 nm that originated from the transition of Yb(3+):(2)F(5/2)→(2)F(7/2) was generated as a result of energy transfer from oxygen interstitials in ZnO nanocrystals to Yb(3+) with energy transfer efficiency of about 10%. The quantum yield for the near-IR emission of Yb(3+) under the excitation of 390 nm was about 16.7%. These materials have potential application in achieving high-efficiency Si solar cells via spectrum modification

    Preparation and luminescence properties of Ce3+ and Tb3+ co-doped glasses and glass ceramics containing SrF2 nanocrystals

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    International audienceThe Ce3+ and Tb3+ co-doped glasses and glass ceramics containing SrF2 nanocrystals were prepared by melt-quenching and subsequent heat treating and their luminescence properties were described. The formation of SrF2 nanocrystals in glass ceramics was confirmed by X-ray diffraction and transmission electron microscopy. The XRD patterns and photoluminescence spectra revealed that the Ce3+ ions and Tb3+ ions have been incorporated into SrF2 nanocrystals. The decay time of excited states has been used to reveal the energy transfer mechanism between Ce3+ and Tb3+. The emission intensity of Tb3+ ions in the glass ceramics was much stronger than that in the precursor glass, which could be ascribed to the more efficient energy transfer from Ce3+ to Tb3+ in the glass ceramics due to the enrichment of Ce3+ and Tb3+ ions and the shortening of the distance between Ce3+ and Tb3+ ions in the precipitated SrF2 nanocrystals. The glasses and glass ceramics could emit bright green light by adjusting concentration ratio of Ce3+ to Tb3+ and heat treatment temperature

    Spectroscopic properties of Er3+/Yb3+ co-doped 50SiO2-20Al2O3-30CaF2 glass and glass ceramics

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    International audienceA spectroscopic investigation of Er3+/Yb3+ co-doped 50SiO2-20Al2O3-30CaF2 glasses and transparent glass ceramics containing CaF2 nanocrystals is presented. The formation of CaF2 nanocrystals in the glass ceramic was confirmed by x-ray diffraction (XRD) and transmission electron microscopy (TEM). The Judd-Ofelt parameters of the Er3+ ions in the glass and glass ceramic have been calculated; they suggested that Er3+ ions had been incorporated into CaF2 nanocrystals in the glass ceramics. The upconversion luminescence intensity of the Er3+/Yb3+ co-doped glass ceramic was much stronger than that of the Er3+/Yb3+ co-doped glass. The upconversion luminescence mechanism has been ascribed to a two-photon absorption process for the green and red luminescence and a three-photon absorption process for the blue luminescence

    Luminescence behavior of Er3+ doped glass ceramics containing Sr2RF7 (R=Y, Gd, La) nanocrystals

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    International audienceThe luminescence behaviors of Er3+ doped glass ceramics containing Sr2RF7 (R = Y,Gd,La) nanocrystals were investigated. The formation of Sr2RF7 nanocrystals in the glass ceramics was confirmed by x-ray diffraction and high resolution transmission electron microscopy. Energy dispersive x-ray spectroscopy analysis showed that the Er3+ ions were efficiently incorporated in Sr2GdF7 nanocrystals. The efficient upconversion luminescence of the Er3+ in the glass ceramics can be observed. The lifetime of the Er3+ in the glass ceramics was found to be much longer than that in the glass due to the lower phonon energy of fluoride crystals when Er3+ entered efficiently fluoride crystals in the glass ceramics

    Luminescence Properties of Eu2+-Doped Glass Ceramics Containing SrF2 Nanocrystals

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    International audienceThe Eu2+-doped glasses and glass ceramics containing SrF2 nanocrystals were prepared and their luminescence properties were investigated. The formation of SrF2 nanocrystals in glass ceramics was confirmed by X-ray diffraction and transmission electron microscopy. The melting in a reducing atmosphere and then the crystallization of glass resulted in the reduction of almost all Eu3+ ions to Eu2+ ions in the glass ceramics. The Eu2+-doped glass ceramics containing SrF2 nanocrystals exhibited a much stronger broad blue emission band and a longer lifetime of excited state than the glasses

    Spectroscopic properties of Er3+-Yb3+ co-doped glass ceramics containing BaF2 nanocrystals

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    International audienceA Er3+ and Yb3+ co-doped transparent oxyfluoride glass ceramic containing BaF2 nanocrystals has been prepared. The formation of BaF2 nanocrystals in the glass ceramic was confirmed by X-ray diffraction. Intense upconversion luminescence in the Er3+ and Yb3+ co-doped glass ceramic could be observed. Stark splitting of the Er3+ upconversion luminescence peaks in the glass ceramic indicated that Er3+ and Yb3+ had been incorporated into the BaF2 nanocrystals. Near infrared luminescence decay curves showed that the Er3+ and Yb3+ co-doped glass ceramic had higher luminescence efficiency than the precursor glass

    Preparation process and upconversion luminescence of Er3+-Doped glass ceramics containing Ba2LaF7 nanocrystals.

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    International audienceThe preparation process and upconversion luminescence of the Er(3+)-doped glass ceramics containing Ba(2)LaF(7) nanocrystals were investigated. The formation of Ba(2)LaF(7) nanocrystals in the glass ceramics was confirmed by X-ray diffraction. Er(3+)-doped glass ceramics containing Ba(2)LaF(7) nanocrystals exhibited highly efficient upconversion luminescence in comparison with glasses. With the increase of heat treatment temperature the upconversion luminescence intensity increased gradually. The composition of glasses was also found to have significant influence on the crystallization process of glass ceramics. The mixture of Ba(2)LaF(7) and La(2)O(3) nanocrystals and the mixture of La(2)F(3) and La(2)O(3) nanocrystals in the glass ceramics could be obtained by controlling different compositions of glasses. The upconversion luminescence intensity also varied significantly with different nanocrystals in the glass ceramics
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