以“四季”小白菜为试材,采用短波UV-C结合LED白光辐照,0.03 mm PE袋包装,于20℃下贮藏,研究不同处理对小白菜贮藏期间的感官品质、损耗率、失重率、叶绿素含量、维生素C含量、丙二醛(MDA)含量、过氧化物酶(POD)及过氧化氢酶(CAT)活性...以“四季”小白菜为试材,采用短波UV-C结合LED白光辐照,0.03 mm PE袋包装,于20℃下贮藏,研究不同处理对小白菜贮藏期间的感官品质、损耗率、失重率、叶绿素含量、维生素C含量、丙二醛(MDA)含量、过氧化物酶(POD)及过氧化氢酶(CAT)活性的影响,以期为采后光辐照处理小白菜贮藏保鲜技术的研究提供参考依据。结果表明:短波UV-C结合LED白光辐照可显著提高小白菜的感官品质,降低其损耗率和失重率,保持较高的叶绿素含量和维生素C含量,减缓MDA含量的积累,同时提高了POD活性和CAT活性。因此,短波UV-C结合LED白光辐照处理对小白菜采后贮藏起到较好的保鲜作用。展开更多
The objective of this work is to simulate a single quantum well ultraviolet light emitting diode(LED) based on AlGaN/GaN/AlGaN and AlGaN/BGaN/AlGaN, by using TCAD Silvaco simulator. The first structure has a GaN quant...The objective of this work is to simulate a single quantum well ultraviolet light emitting diode(LED) based on AlGaN/GaN/AlGaN and AlGaN/BGaN/AlGaN, by using TCAD Silvaco simulator. The first structure has a GaN quantum well taken between two layers, of n-AlGaN and p-AlGaN. The second one has a BGaN quantum well instead of GaN. We fix the concentration of the boron in BGaN to only 1% and we vary the thickness of GaN and BGaN quantum well layer from 7 to 20 nm, for the two structures. As results, we obtain respectively for GaN-LED and BGaN-LED, a maximum current of 0.52 and 0.27 mA, a maximum power spectral density of 1.935 and 6.7 W cm^(-1) eV^(-1), a maximum spontaneous emission of 3.34 × 10^(28) and 3.43 × 10^(28) s^(-1) cm^(-3) eV^(-1), and a maximum Light output power of 0.56 and 0.89 mW.展开更多
文摘以“四季”小白菜为试材,采用短波UV-C结合LED白光辐照,0.03 mm PE袋包装,于20℃下贮藏,研究不同处理对小白菜贮藏期间的感官品质、损耗率、失重率、叶绿素含量、维生素C含量、丙二醛(MDA)含量、过氧化物酶(POD)及过氧化氢酶(CAT)活性的影响,以期为采后光辐照处理小白菜贮藏保鲜技术的研究提供参考依据。结果表明:短波UV-C结合LED白光辐照可显著提高小白菜的感官品质,降低其损耗率和失重率,保持较高的叶绿素含量和维生素C含量,减缓MDA含量的积累,同时提高了POD活性和CAT活性。因此,短波UV-C结合LED白光辐照处理对小白菜采后贮藏起到较好的保鲜作用。
基金supported by the University of Abou-Bekr-Belkaid, Materials and Renewable Energy Research Unit, Tlemcen, Algeria
文摘The objective of this work is to simulate a single quantum well ultraviolet light emitting diode(LED) based on AlGaN/GaN/AlGaN and AlGaN/BGaN/AlGaN, by using TCAD Silvaco simulator. The first structure has a GaN quantum well taken between two layers, of n-AlGaN and p-AlGaN. The second one has a BGaN quantum well instead of GaN. We fix the concentration of the boron in BGaN to only 1% and we vary the thickness of GaN and BGaN quantum well layer from 7 to 20 nm, for the two structures. As results, we obtain respectively for GaN-LED and BGaN-LED, a maximum current of 0.52 and 0.27 mA, a maximum power spectral density of 1.935 and 6.7 W cm^(-1) eV^(-1), a maximum spontaneous emission of 3.34 × 10^(28) and 3.43 × 10^(28) s^(-1) cm^(-3) eV^(-1), and a maximum Light output power of 0.56 and 0.89 mW.
文摘氮化铝(AlN)作为一种宽带隙半导体,具有优异的物理和化学性能,在紫外发光二极管(Light Emitting Diode,LED)领域有着广泛的应用。同样,发展较为成熟的氮化镓(GaN)在该领域也有着不可替代的作用。而高性能的器件需要有良好的外延层。AlGaN基紫外LED外延层的传统制备方法是采用金属有机化学气相沉积法(Metal Organic Chemical Vapor Deposition,MOCVD),但是由于该方法中存在着强烈的预反应和Al原子本身迁移速率慢等原因,导致外延层中出现大量缺陷,使得紫外LED器件的性能降低。此外,由于不同材料以及材料与空气的折射率存在差异,使得光难以逃逸到外界,大部分光被局域在芯片内部,从而降低光提取效率以及光强。为了提高器件的光学性能,一种新的紫外LED结构被提出,文章采用时域有限差分模拟(Finite Difference Time Domain,FDTD)软件对该外延结构的光提取效率和出光强度进行了仿真。研究发现,与传统的LED结构相比,新型紫外LED结构的横磁波(TM)光模式和横电波(TE)光模式的光提取效率分别提高了19.1%和29.3%,最大出光强度分别提高了42.78%和47.18%,对器件的光学性能有着显著的改善。另外,文章还研究了新型紫外LED外延层的结构参数对器件整体光学性能的影响,在光源、物理模型尺寸和仿真条件等因素不变的情况下,获得了光学性能最佳的结构参数。
