150 research outputs found

    Educating L2 learners about collaborative writing: exploring the relationship between knowledge of collaborative writing and writing products

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    Although research about the effectiveness of second or foreign language collaborative writing for jointly written products has proliferated in the last few decades, there has been less examination of whether and how pre-task preparation could maximize the language learning opportunities that collaborative writing can afford learners. Informed by metacognition theory, this study used a mixed-methods approach to investigate the impacts of one technique for preparing students, namely educating them about collaborative writing knowledge. This study compared collaborative writing products from two parallel classes (one with exposure to explicit collaborative writing knowledge and one without) to investigate whether and how knowledge about collaborative writing affected the complexity, fluency, accuracy, and quality of collaboratively drafted essays. The findings indicated that students who were exposed to collaborative writing knowledge outperformed those who were not in terms of the accuracy, fluency, and quality (content, organization, grammar, and vocabulary) of their collaboratively drafted essays. The findings also revealed that knowledge of collaborative writing affects the quality of collaboratively drafted essays from the perspective of metacognitive strategies, namely planning, monitoring, and evaluating one’s own writing process.</p

    A Genetically Encoded FRET Sensor for Hypoxia and Prolyl Hydroxylases

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    Oxygen is vital for all aerobic life forms. Oxygen-dependent hydroxylation of hypoxia-inducible factor (HIF)-1α by prolyl hydroxylase domain enzymes (PHDs) is an important step for controlling the expression of oxygen-regulated genes in metazoan species, thereby constituting a molecular mechanism for oxygen sensing and response. Herein, we report a genetically encoded dual-emission ratiometric fluorescent sensor, ProCY, which responds to PHD activities <i>in vitro</i> and in live cells. We demonstrated that ProCY could monitor hypoxia in mammalian cells. By targeting this novel genetically encoded biosensor to the cell nucleus and cytosol, we determined that, under normoxic conditions, the HIF-prolyl hydroxylase activity was mainly confined to the cytosol of HEK 293T cells. The results collectively suggest broad applications of ProCY on the evaluation of hypoxia and PHD activities and understanding of pathways for the control of hypoxic responses

    Light Activation of Protein Splicing with a Photocaged Fast Intein

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    Intein-mediated protein splicing has found broad biotechnological applications. Herein, we describe our recent result in engineering a photoactivatable intein compatible with living mammalian cells. A photocaged cysteine amino acid residue was genetically introduced into a highly efficient Nostoc punctiforme (Npu) DnaE intein. The resulting photocaged intein was inserted into a red fluorescent protein (RFP) mCherry and a human Src tyrosine kinase to create inactive chimeric proteins. A light-induced photochemical reaction was able to reactivate the intein and trigger protein splicing. Active mCherry and Src were formed as observed by direct fluorescence imaging or imaging of an Src kinase sensor in mammalian cells. The genetically encoded photocaged intein is a general optogenetic tool, allowing effective photocontrol of primary structures and functions of proteins

    Inner wall temperature cooling curves of steel pipe for 5s spraying.

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    <p>Inner wall temperature cooling curves of steel pipe for 5s spraying.</p

    Heat Transfer Modeling of an Annular On-Line Spray Water Cooling Process for Electric-Resistance-Welded Steel Pipe

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    <div><p>On-line spray water cooling (OSWC) of electric-resistance-welded (ERW) steel pipes can replace the conventional off-line heat treatment process and become an important and critical procedure. The OSWC process improves production efficiency, decreases costs, and enhances the mechanical properties of ERW steel pipe, especially the impact properties of the weld joint. In this paper, an annular OSWC process is investigated based on an experimental simulation platform that can obtain precise real-time measurements of the temperature of the pipe, the water pressure and flux, etc. The effects of the modes of annular spray water cooling and related cooling parameters on the mechanical properties of the pipe are investigated. The temperature evolutions of the inner and outer walls of the pipe are measured during the spray water cooling process, and the uniformity of mechanical properties along the circumferential and longitudinal directions is investigated. A heat transfer coefficient model of spray water cooling is developed based on measured temperature data in conjunction with simulation using the finite element method. Industrial tests prove the validity of the heat transfer model of a steel pipe undergoing spray water cooling. The research results can provide a basis for the industrial application of the OSWC process in the production of ERW steel pipes.</p></div

    Internal structure of cooling box.

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    <p>Internal structure of cooling box.</p

    Inner wall temperature cooling curves of steel pipe for 10s spraying.

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    <p>Inner wall temperature cooling curves of steel pipe for 10s spraying.</p

    Graphene Surface-Anchored Fluorescence Sensor for Sensitive Detection of MicroRNA Coupled with Enzyme-Free Signal Amplification of Hybridization Chain Reaction

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    A new enzyme-free signal amplification-based assay for microRNA (miRNA) detection is developed by using hybridization chain reaction (HCR) coupled with a graphene oxide (GO) surface-anchored fluorescence signal readout pathway. MiRNAs can efficiently initiate HCR between two species of fluorescent hairpin probes. After HCR, both of the excess hairpin probes and the HCR products will be anchored on the GO surface. The fluorescence of the hairpin probes can be completely quenched by GO, whereas the HCR products maintain strong fluorescence. Therefore, integrating HCR strategy for signal amplification with selective fluorescence quenching effects of GO provides a versatile miRNA assay

    Arrangement of nozzles for spray water cooling system.

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    <p>(A) Centripetal. (B) Tangential to a circle of radius <i>r</i>.</p

    Mechanical properties and cooling temperatures at different spraying pressures.

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    <p>Mechanical properties and cooling temperatures at different spraying pressures.</p
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