13 research outputs found

    Table_1_Factors influencing secondary school students’ reading literacy: An analysis based on XGBoost and SHAP methods.docx

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    This paper constructs a predictive model of student reading literacy based on data from students who participated in the Program for International Student Assessment (PISA 2018) from four provinces/municipalities of China, i.e., Beijing, Shanghai, Jiangsu and Zhejiang. We calculated the contribution of influencing factors in the model by using eXtreme Gradient Boosting (XGBoost) algorithm and sHapley additive exPlanations (SHAP) values, and get the following findings: (1) Factors that have the greatest impact on students’ reading literacy are from individual and family levels, with school-level factors taking a relative back seat. (2) The most important influencing factors at individual level are reading metacognition and reading interest. (3) The most important factors at family level are ESCS (index of economic, social and cultural status) and language environment, and dialect is negative for reading literacy, whereas proficiency in both a dialect and Mandarin plays a positive role. (4) At the school level, the most important factors are time dedicated to learning and class discipline, and we found that there is an optimal value for learning time, which suggests that reasonable learning time is beneficial, but overextended learning time may make academic performance worse instead of improving it.</p

    Fabrication of Core–Sheath NiCoP@FeP<sub><i>x</i></sub> Nanoarrays for Efficient Electrocatalytic Hydrogen Evolution

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    Construction of effective, stable, eco-friendly, and earth-abundant electrocatalysts that substitute noble metals for hydrogen evolution reaction (HER) is essential for developing renewable and clean energy. Here we report a layer-by-layer assembly route to fabricate core–sheath structured nanoarrays composed of nickel cobalt phosphide and iron phosphide (NCP@FeP<sub><i>x</i></sub>) on a conductive Ni wire by atomic layer deposition (ALD). The as-fabricated multimetallic phosphide exhibits high electrocatalytic activity in both alkaline and acidic media, with small overpotentials of 82.5 and 96 mV at 10 mA cm<sup>–2</sup>, respectively. The self-supported electrode displays superior long-term stability and favorable durability. The excellent activity is originated from the unique core–sheath structure, and the synergistic effects of the FePx sheath and the NCP core contributed to the enhanced activity. The present ALD-assisted layer-by-layer strategy may provide a general route for the controlled fabrication of nanostructured electrocatalysts with tunable compositions and surfaces

    <i>Citrobacter amalonaticus</i> Phytase on the Cell Surface of <i>Pichia pastoris</i> Exhibits High pH Stability as a Promising Potential Feed Supplement

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    <div><p>Phytase expressed and anchored on the cell surface of <i>Pichia pastoris</i> avoids the expensive and time-consuming steps of protein purification and separation. Furthermore, yeast cells with anchored phytase can be used as a whole-cell biocatalyst. In this study, the phytase gene of <i>Citrobacter amalonaticus</i> was fused with the <i>Pichia pastoris</i> glycosylphosphatidylinositol (GPI)-anchored glycoprotein homologue <i>GCW61</i>. Phytase exposed on the cell surface exhibits a high activity of 6413.5 U/g, with an optimal temperature of 60°C. In contrast to secreted phytase, which has an optimal pH of 5.0, phytase presented on the cell surface is characterized by an optimal pH of 3.0. Moreover, our data demonstrate that phytase anchored on the cell surface exhibits higher pH stability than its secreted counterpart. Interestingly, our <i>in vitro</i> digestion experiments demonstrate that phytase attached to the cell surface is a more efficient enzyme than secreted phytase.</p></div

    Phytase activity after induction with methanol and after treatment with laminarinase.

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    <p>A: Time dependence of the activity of cell surface phytase after induction with methanol. B: Cell surface phytase activity after laminarinase treatment. Column 1 represents cell wall fractions without treatment with laminarinase. Columns 2 and 4 represent cell wall fractions after laminarinase treatment, and column 3 and 5 represent supernatant fractions after laminarinase treatment. Columns 2 and 3 show phytase activities after treatment with 5 mU of laminarinase, while columns 4 and 5 represent the remaining activities after treatment with 50 mU of laminarinase. All activities were compared to the activity of the whole cell surface phytase, with GS115/ZαA as a background measurement.</p

    Effect of metal ions on cell surface and secreted phytases.

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    <p>The counter of all metals was chloride. <i><sup>b</sup></i>Without metal ion added (as 100%). <i><sup>c</sup></i>Values in the same column differ significantly from values without metal added (<i>p</i><0.05).</p><p>Effect of metal ions on cell surface and secreted phytases.</p

    <i>In vitro</i> digestibility test of cell surface and secreted phytases.

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    <p>A: Measured phosphate (Pi) released from a corn-based diet mixed with cell surface or secreted phytases. B: Simulation of the pelleting process (i.e., incubation for 3 min at 80°C or 5 min at 90°C prior to activity measurement), followed by determination of the amount of released Pi. The levels of released Pi were compared with samples without heat treatment. GS115/ZαA served as a background measurement.</p

    Fluorescence microscopy and flow cytometry analyses of yeast cells.

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    <p>Fluorescence microscopy and flow cytometry analyses of yeast cells.</p

    Constructing Three-Dimensional Honeycombed Graphene/Silicon Skeletons for High-Performance Li-Ion Batteries

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    Silicon has been considered to be an attractive high-capacity anode material for next-generation lithium-ion batteries (LIBs). Currently, the commercial application of Si-based anodes is still restricted by its limited cycle life and rate capacity, which could be ascribed to the colossal volumetric change during the cycling process and poor electronic conductivity. We report the design of a unique Si-based nanocomposite of three-dimensional (3D) honeycombed graphene aerogel and the reduced graphene oxide sheets preprotected silicon secondary particles (SiNPs@rGO1). Through simple electrostatic self-assembly and hydrothermal processes, SiNPs are able to be wrapped with rGO1 to form reunited SiNPs@rGO1, and embedded into the backbone of 3D graphene honeycomb (rGO2). Such an intriguing design (namely, SiNPs@rGO1/rGO2) not only provides a conductive skeleton to improve the electrical conductivity, but also possesses abundant void spaces to accommodate the dramatic volume changes of SiNPs. Meanwhile, the outer rGO1 coats protect the inner SiNPs away from the electrolyte and prevent the destruction of the solid electrolyte interphase (SEI) film. As a result, the 3D honeycombed architecture achieves a high cyclability and excellent rate capability

    Free-Standing Mn<sub>3</sub>O<sub>4</sub>@CNF/S Paper Cathodes with High Sulfur Loading for Lithium–Sulfur Batteries

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    Free-standing paper cathodes with layer-by-layer structure are synthesized for high-loading lithium–sulfur (Li–S) battery. Sulfur is loaded in a three-dimensional (3D) interconnected nitrogen-doped carbon nanofiber (CNF) framework impregnated with Mn<sub>3</sub>O<sub>4</sub> nanoparticles. The 3D interconnected CNF framework creates an architecture with outstanding mechanical properties. Synergetic effects generated from physical and chemical entrapment could effectively suppress the dissolution and diffusion of the polysulfides. Electrochemical measurements suggest that the rationally designed structure endows the electrode with high utilization of sulfur and good cycle performance. Specifically, the cathode with a high areal sulfur loading of 11 mg cm<sup>–2</sup> exhibits a reversible areal capacity over 8 mAh cm<sup>–2</sup>. The fabrication procedure is of low cost and readily scalable. We believe that this work will provide a promising choice for potential practical applications
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