Emission Mechanism of High Al-content AlGaN Multiple Quantum Wells

紫外LED的发光功率和效率还远不能令人们满意,波长短于300 nm的深紫外LED的发光效率普遍较低。厘清高Al组分Al Ga N多量子阱结构的发光机制将有利于探索改善深紫外LED的发光效率的新途径、新方法。为此,本文通过金属有机气相外延技术外延生长了表面平整、界面清晰可辨且陡峭的高Al组分AlGa N多量子阱结构材料,并对其进行变温光致发光谱测试,结合数值计算,深入探讨了Al Ga N量子阱的发光机制。研究表明,量子阱中具有很强的局域化效应,其发光和局域激子的跳跃息息相关,而发光的猝灭则与局域激子的解局域以及位错引起的非辐射复合有关。The quantum efficiency of deep UV light emitting diodes( LED) drops dramatically with the increasing of Al content. Understanding the emission mechanism of high Al-content Al Ga N multiple quantum wells( MQW) is the one of the most important objects for improving the quantum efficiency of deep UV LED. In this work,high Al-content Al Ga N MQW structure with atomically flat hetero-interfaces was grown and characterized by photoluminescence( PL) measurements at different temperatures. The results indicate that there is a strong exciton-localization effect in the MQW structure and the emission is closely related to the hopping of the excitons. Due to the exciton delocalization and nonradiative recombination at defects,the PL intensity is strongly quenched at high temperatures.“973”国家重点基础研究发展计划(2012CB619300);; “863”国家高技术研究发展计划(2014AA032608);; 国家自然科学基金(U1405253;61227009;11204254;11404271);; 福建省自然科学基金(2015J01028)资助项

Correlation between length of stay in acute stroke wards and the functional prognosis after comprehensive rehabilitation

　脳卒中発症後の機能予後改善には回復期リハビリテーションが有効である．急性期病棟から回復期リハビリテーション病棟に早期に移ることが，機能予後改善につながる可能性がある．本研究では，急性期病棟の在院期間と長期予後改善効果の関連性を検討することを目的とした．2018年１月1日から2018年12月31日までに川崎医科大学附属病院脳卒中科に入院した急性期脳卒中症例のうち，回復期リハビリテーション病棟に転棟・転院した症例を対象とした．脳卒中科退院時に比し，一年後に modified Rankin scale が１以上改善した症例を改善有と定義した．改善有と関連する患者背景因子，入院中の診療データについて検討を行った．関連性はカイ二乗検定を用いて評価し，有意な関連性を示した因子についてはロジスティック回帰分析を用いて解析した．対象期間に入院した急性期脳卒中408例中，回復期リハビリテーション病棟に転棟・転院したのは142例であった（男性90人，中央値76.0歳）．改善有は57例であり，在院期間の第一四分位である17日未満で回復期病棟に移った群で改善有が有意に多かった（P < 0.01）．ロジスティック回帰分析でも急性期病棟の在院期間が短い（17日未満）ことが改善有と独立して関連した．急性期脳卒中患者の急性期病棟在院期間を短縮することが機能予後改善につながることが示唆された．　Neurological symptoms and functional disability of stroke survivors can be improved through comprehensive rehabilitation in the post-acute phase. Early transfer from the stroke unit to the rehabilitation ward possibly leads to an improvement of functional prognosis. The purpose of this study was to investigate the relationship between the length of stay in the stroke unit and the long-term prognosis improvement. The study involved acute stroke patients admitted to the Department of Stroke, Kawasaki Medical School Hospital between January 1, 2018 and December 31, 2018. Specifically, those selected and included in the study were patients eventually transferred to a rehabilitation department or hospital. Improvement of functional prognosis was defined as a 1-point decrease on the modified Rankin scale at 1 year compared with that at the time of discharge from the stroke department. Factors associated with the improvement group were evaluated using the chi-square test and then logistic regression analysis. Of the 408 patients with acute stroke admitted during the study period, 142 were transferred to rehabilitation centers (90 men, median age: 76.0 years). Fifty-seven patients had improvement. The rate of improvement was significantly higher in the group transferred to the rehabilitation ward by day 17, the first quartile of time in the stroke unit (p < 0.01). Logistic regression analysis also showed that a shorter length of stay (< 17 days) in the stroke unit was independently associated with improvement. The results suggest that early initiation of comprehensive rehabilitation in the post-acute phase leads to improved functional outcomes of patients with acute stroke

北極海におけるカイアシ類の季節変動と食性の種間比較に関する研究 [全文の要約]

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