1,348 research outputs found

    Historical water level change of Lake Weishan in East China from 1758–1902 AD: relationship with the flooding of the Yellow River

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    published_or_final_versionSpringer Open Choice, 28 May 201

    Satellite estimates of wide-range suspended sediment concentrations in Changjiang (Yangtze) estuary using MERIS data

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    The Changjiang (Yangtze) estuarine and coastal waters are characterized by suspended sediments over a wide range of concentrations from 20 to 2,500 mg l-1. Suspended sediment plays important roles in the estuarine and coastal system and environment. Previous algorithms for satellite estimates of suspended sediment concentration (SSC) showed a great limitation in that only low to moderate concentrations (up to 50 mg l-1) could be reliably estimated. In this study, we developed a semi-empirical radiative transfer (SERT) model with physically based empirical coefficients to estimate SSC from MERIS data over turbid waters with a much wider range of SSC. The model was based on the Kubelka–Munk two-stream approximation of radiative transfer theory and calibrated using datasets from in situ measurements and outdoor controlled tank experiments. The results show that the sensitivity and saturation level of remote-sensing reflectance to SSC are dependent on wavelengths and SSC levels. Therefore, the SERT model, coupled with a multi-conditional algorithm scheme adapted to satellite retrieval of wide-range SSC, was proposed. Results suggest that this method is more effective and accurate in the estimation of SSC over turbid water

    Hierarchical CO2-protective shell for highly efficient oxygen reduction reaction

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    The widespread application of intermediate-temperature solid oxide fuel cells is mainly being hurdled by the cathode's low efficiency on oxygen reduction reaction and poor resistance to carbon dioxide impurity. Here we report the fabrication of a hierarchical shell-covered porous cathode through infiltration followed by microwave plasma treatment. The hierarchical shell consists of a dense thin-film substrate with cones on the top of the substrate, leading to a three-dimensional (3D) heterostructured electrode. The shell allows the cathode working stably in CO2-containing air, and significantly improving the cathode's oxygen reduction reactivity with an area specific resistance of ∼0.13 Ωcm2 at 575°C. The method is also suitable for fabricating functional shell on the irregularly shaped substrate in various applications

    Heterostructured electrode with concentration gradient shell for highly efficient oxygen reduction at low temperature

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    Heterostructures of oxides have been widely investigated in optical, catalytic and electrochemical applications, because the heterostructured interfaces exhibit pronouncedly different transport, charge, and reactivity characteristics compared to the bulk of the oxides. Here we fabricated a three-dimensional (3D) heterostructured electrode with a concentration gradient shell. The concentration gradient shell with the composition of Ba0.5-xSr0.5-yCo0.8Fe0.2O3-δ (BSCF-D) was prepared by simply treating porous Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF) backbone with microwave-plasma. Electrochemical impedance spectroscopy reveals that the oxygen surface exchange rate of the BSCF-D is enhanced by ~250% that of the pristine BSCF due to the appearance of the shell. The heterostructured electrode shows an interfacial resistance as low as 0.148 Ω cm2 at 550°C and an unchanged electrochemical performance after heating treatment for 200 h. This method offers potential to prepare heterostructured oxides not only for electrochemical devices but also for many other applications that use ceramic materials

    Analysis of Risk Factors for Intraoperative Bleeding in the Surgical Treatment of Cesarean Scar Pregnancy and Development of Predictive Models

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    Xiao-Li Wan,1 Xu Wang,1 Zhi-Ping Feng,1 Xiao-Ling Zhou,1 Zhen-Wen Han,1 Jia-Mei Wu,1 Hong-Mei Xu,1 Ting Hu2 1Department of Gynaecology and Obstetrics, People’s Hospital of Leshan, Leshan, Sichuan, 614000, People’s Republic of China; 2Department of Gynaecological Oncology, Sichuan Clinical Research Center for Cancer, Sichuan Cancer Hospital & Institute, Sichuan Cancer Center, Affiliated Cancer Hospital of University of Electronic Science and Technology of China, Chengdu, Sichuan, 610041, People’s Republic of ChinaCorrespondence: Ting Hu, Department of Gynaecological Oncology, Sichuan Clinical Research Center for Cancer, Sichuan Cancer Hospital & Institute, Sichuan Cancer Center, Affiliated Cancer Hospital of University of Electronic Science and Technology of China, 55 Section 4, Renmin South Road, Chengdu, Sichuan, 610041, People’s Republic of China, Tel +86 18615786531, Email [email protected] Hong-Mei Xu, Department of Gynaecology and Obstetrics, People’s Hospital of Leshan, No. 238 of BaiTa Street, Shizhong District, Leshan, Sichuan, 614000, People’s Republic of China, Tel +86 18981392030, Email [email protected]: The objective of this study was to investigate the risk factors associated with cesarean scar pregnancy (CSP) and to develop a model for predicting intraoperative bleeding risk.Methods: We retrospectively analyzed the clinical data of 208 patients with CSP who were admitted to the People’s Hospital of Leshan between January 2018 and December 2022. Based on whether intraoperative bleeding was ≥ 200 mL, we categorized them into two groups for comparative analysis: the excessive bleeding group (n = 27) and the control group (n = 181). Identifying relevant factors, we constructed a prediction model and created a nomogram.Results: We observed that there were significant differences between the two groups in several parameters. These included the time of menstrual cessation (P = 0.002), maximum diameter of the gestational sac (P < 0.001), thickness of the myometrium at the uterine scar (P = 0.001), pre-treatment blood HCG levels (P = 0.016), and the grade of blood flow signals (P < 0.001). We consolidated the above data and constructed a clinical prediction model. The model exhibited favorable results in terms of predictive efficacy, discriminative ability (C-index = 0.894, specificity = 0.834, sensitivity = 0.852), calibration precision (mean absolute error = 0.018), and clinical decision-making utility, indicating its effectiveness.Conclusion: The clinical prediction model related to the risk of hemorrhage that we developed in this experiment can assist in the development of appropriate interventions and effectively improve patient prognosis.Keywords: cesarean section, prediction modeling, risk factors, uterine scar pregnanc

    Optimisation of substrate angles for multi-material and multi-functional inkjet printing

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    Three dimensional inkjet printing of multiple materials for electronics applications are challenging due to the limited material availability, inconsistencies in layer thickness between dissimilar materials and the need to expose the printed tracks of metal nanoparticles to temperature above 100 °C for sintering. It is envisaged that instead of printing a dielectric and a conductive material on the same plane, by printing conductive tracks on an angled dielectric surface, the required number of silver layers and consequently, the exposure of the polymer to high temperature and the build time of the component can be significantly reduced. Conductive tracks printed with a fixed print height (FH) showed significantly better resolution for all angles than the fixed slope (FS) sample where the print height varied to maintain the slope length. The electrical resistance of the tracks remained under 10Ω up to 60° for FH; whereas for the FS samples, the resistance remained under 10Ω for samples up to 45°. Thus by fixing the print height to 4 mm, precise tracks with low resistance can be printed at substrate angles up to 60°. By adopting this approach, the build height “Z” can be quickly attained with less exposure of the polymer to high temperature

    ISRM-Suggested Method for Determining the Mode I Static Fracture Toughness Using Semi-Circular Bend Specimen

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    The International Society for Rock Mechanics has so far developed two standard methods for the determination of static fracture toughness of rock. They used three different core based specimens and tests were to be performed on a typical laboratory compression or tension load frame. Another method to determine the mode I fracture toughness of rock using semicircular bend specimen is herein presented. The specimen is semicircular in shape and made from typical cores taken from the rock with any relative material directions noted. The specimens are tested in three-point bending using a laboratory compression test instrument. The failure load along with its dimensions is used to determine the fracture toughness. Most sedimentary rocks which are layered in structure may exhibit fracture properties that depend on the orientation and therefore measurements in more than one material direction may be necessary. The fracture toughness measurements are expected to yield a size-independent material property if certain minimum specimen size requirements are satisfied

    Observation of a ppb mass threshoud enhancement in \psi^\prime\to\pi^+\pi^-J/\psi(J/\psi\to\gamma p\bar{p}) decay

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    The decay channel ψπ+πJ/ψ(J/ψγppˉ)\psi^\prime\to\pi^+\pi^-J/\psi(J/\psi\to\gamma p\bar{p}) is studied using a sample of 1.06×1081.06\times 10^8 ψ\psi^\prime events collected by the BESIII experiment at BEPCII. A strong enhancement at threshold is observed in the ppˉp\bar{p} invariant mass spectrum. The enhancement can be fit with an SS-wave Breit-Wigner resonance function with a resulting peak mass of M=186113+6(stat)26+7(syst)MeV/c2M=1861^{+6}_{-13} {\rm (stat)}^{+7}_{-26} {\rm (syst)} {\rm MeV/}c^2 and a narrow width that is Γ<38MeV/c2\Gamma<38 {\rm MeV/}c^2 at the 90% confidence level. These results are consistent with published BESII results. These mass and width values do not match with those of any known meson resonance.Comment: 5 pages, 3 figures, submitted to Chinese Physics
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