白光LED用稀土红色荧光粉研究进展

白光LED因其具有功耗低、发光效率高、寿命长等特点被广泛应用,蓝光LED芯片激发黄色荧光粉是实现白光LED的主流方法,因其先天缺少红光成分使其显色指数低、色温高,加入红色荧光粉对调节显色指数和色温有重要意义,本文主要介绍白光LED用红色荧光粉主要系列材料红色荧光粉的研究进展。     

LED警示服的发光性能测试方法研究

研究LED警示服发光性能的测试方法,采用亮度计和照度计分别测量警示服表面LED发光的平均亮度和平均照度;用万用表测量警示服的工作电压和电流;根据相关公式计算LED警示服的光通量和发光效能,用亮度、光通量和发光效能3个指标评价LED警示服的发光性能。该方法的建立可以为LED警示服的生产和质量监督提供检测依据。     

温度与电流对于白光LED发光效率的影响分析

LED工作过程中,较高的工作温度或是较大的工作电流会严重影响发光效率。如果LED显示器工作的温度超出芯片承载温度,就导致LED显示屏发光效率的减小,出现光衰现象,同时对LED显示屏造成损坏,而LED显示器的工作电流超出芯片的饱和电流,也会导致LED显示器的损坏。因此,研究与分析温度、电流对白光LED发光效率的影响十分重要。     

GaN基白光LED的荧光粉涂层封装技术研究

本文所研究的是利用GaN基半导体芯片发出蓝色光后通过荧光粉转换成白光的LED技术。本文的重点环节是在于对LED制作过程中的将蓝色光转换成白光的荧光粉的平面涂层技术进行详细的分析和研究。     

糖膏非牛顿流体流变特性的实验研究

以甲糖膏为研究对象,考察了其流变特性及锤度、剪切速率、温度和时间对糖膏粘度的影响.在实验条件范围内,结果表明:糖膏呈现拟塑性,并且具有触变性;粘度随锤度的增大而增加;粘度先随温度的升高快速降低,当达到一定温度后粘度缓慢降低;流变指数n随温度的升高而增大,稠度系数K随锤度的增加而降低.最后绘出间歇煮糖过程中流变指数n随煮糖时间变化的曲线和粘度随煮糖时间变化的曲线,为煮糖过程中粘度作为控制参数的在线检测和控制提供理论依据和控制参数值.     

老化对LED光色电参数的影响探究

针对LED产品在使用过程中的老化现象。文章对某品牌LED贴片在室温下进行老练。结果表明,老练后样品相关色温、光通量和正向电压的变化存在一定的联系。     

人工老化对大豆种子活力和生理生化特性的影响

以晋豆19号大豆种子为研究材料,对其进行40℃、100%RH高温高湿老化处理,并对种子发芽指标﹑相对电导率、可溶性糖和丙二醛含量以及4种抗氧化酶活性的变化进行测定。结果表明：随着种子老化加深种子的各发芽指标均逐渐降低,相对电导率、外渗可溶性糖和丙二醛含量逐渐升高,铜锌和总超氧化物歧化酶随老化时间延长而增加,锰超氧化物歧化酶呈波浪式变化,过氧化物酶和谷胱甘肽还原酶活性变化的总趋势是随老化时间延长而降低,而过氧化氢酶呈先升后降趋势。种子活力和生理生化指标之间呈显著的相关性。用该老化方法评价大豆种子耐贮藏性的适宜老化时间在36～60h。在所测定的生理指标中,丙二醛（MDA）含量和过氧化物酶（POD）及谷胱甘肽还原酶（GR）活性与大豆种子活力快速下降相吻合,可作为敏感指标监测大豆种子的劣变状况。     

Ce~(3+)/Mn~(2+)共掺Ca_3Y(PO_4)_3红色荧光粉的制备及其能量传递

为了改善白光LED荧光粉中红光的缺失,采用高温固相法制备Ce~(3+)/Mn~(2+)共掺Ca_3Y(PO_4)_3的新型红色荧光粉。通过X射线衍射(XRD)分析,证明在1 350℃下煅烧10 h,反应结束后应迅速降温才能合成所需样品。在波长325 nm光激发下,Ca_3Y(PO_4)_3∶Ce~(3+), Mn~(2+)样品存在2个发光中心,即383 nm和620 nm,分别对应于Ce~(3+)的5d-4f和Mn~(2+)的~4T_1(~4G)-~6A_1(~6S)的电子跃迁。随着Mn~(2+)离子浓度的增加,样品的发光颜色从蓝光逐渐向红光区域移动,直到Mn~(2+)离子浓度达到0.12 mol时,样品的色度坐标为(0.406, 0.221),位于红光部分。原因在于Ce~(3+)→Mn~(2+)间的能量传递,能量传递机理为电四极-电四极相互作用。由于Mn~(2+)离子发光中心周围的晶体场环境受到Mn~(2+)掺杂浓度的影响而发生改变,使其中心波长从615 nm红移到627 nm。成功合成了一种新型的单一基质的Ca_3Y(PO_4)_3∶Ce~(3+)/Mn~(2+)红色荧光粉,在荧光粉转换白光LED的方案中拥有潜在的应用价值。     

湿热老化过程对桑蚕丝性能与结构的影响

对桑蚕丝织物湿热老化样品进行了相关表征,利用衰减全反射-傅里叶转换光谱技术和红外光谱去卷积拟合计算技术对样品的性能和结构变化情况进行了考察,并用X射线衍射技术考察了样品的结晶度变化规律。结果表明,随着老化时间延长和温湿度的增加,蚕丝断裂强度及白度总体呈下降趋势;湿热老化下,桑蚕丝的β-sheet结构相对百分含量也随时间延长而下降,且同样湿度下,温度越高下降越明显;湿热老化下,桑蚕丝β-sheet结构相对百分含量变化、结晶度与断裂强度及白度的变化趋势相关。     

氙灯老化及汗浸对毛革的影响

采用氙灯光源照射模拟毛革制品的自然老化。测定毛革一些性质变化,以及用人工碱性汗液对老化后的样品做浸泡处理考察。实验发现,相同老化下醛鞣及铬鞣毛革的Ts均有类似下降,而透水汽值增加。汗浸处理后,铬鞣毛革的汗浸出物量随光照时间延长而增加,而醛鞣毛革却逐渐减低;其次,两种样品的相同性是汗浸面积收缩随光照时间延长而增加,而pH值均降低。     

蚕丝织物上茜草染料的光老化

模拟茜草染色丝绸文物在展览时的自然光老化过程,设计了一套系统的光老化实验.采用荧光紫外灯、卤素灯和白光LED灯,对自制茜草染色样品进行光老化实验,得到3种照明条件下染料的褪色规律曲线,并用高效液相色谱对光老化的内在规律和机制进行更进一步的分析.结果表明:紫外辐射对茜草染料破坏较严重;卤素灯照明下染料褪色速率稍慢于LED...     

The effect of LED irradiation on the quality of cabbage stored at a low temperature

The effects of light emitting diode (LED) irradiation on maintaining freshness and nutrition in cabbage during low temperature storage were investigated. Cabbage, ‘Dongdori’ was stored at 4–5°C for 18 days under white, green, blue, and red LED light. On day 15 of storage, the total chlorophyll content of cabbage was highest for green, followed by white, red, blue, and a nonirradiated control group. The vitamin C content was highest for blue, followed by white, green, red, and the control. On day 18 of storage, the total polyphenolic content in cabbage was highest for blue followed by white, red, green, and the control. LED irradiation is effective for enriching the chlorophyll, vitamin C, and polyphenol contents of cabbage stored at a low temperature and results suggest that LED colors have different effects.     

LED光照处理对豇豆采后贮藏品质和生理特征的影响

为探究LED单色光照射对豇豆采后生理特征的影响,采用光照强度为40 μmol·m-2·s-1的LED白光和蓝光两种单色光,在整个贮藏期照射处理豇豆,测定15 ℃贮藏条件下豇豆贮藏品质和生理特性的变化。结果表明:在15 ℃下,LED光照处理有效地延缓豇豆外观品质的下降和失重率的升高,抑制锈斑的产生和发展,减缓可溶性固形物和叶绿素的降解,抑制MDA的积累,有效维持细胞膜的完整性,保持较好的总酚含量,同时增强了POD和CAT抗氧化酶活性,减轻了活性氧对组织细胞的损伤,其中光照强度为40 μmol·m-2·s-1 LED白光的保鲜效果优于光照强度为40 μmol·m-2·s-1 LED蓝光。     

Impact of using Trepat and Monastrell red grape varieties on the volatile and nitrogen composition during the manufacture of rosé Cava sparkling wines

The impact of using Trepat and Monastrell red grape varieties during the manufacture of rosé sparkling Cava wines on the nitrogen and volatile composition compared to a white Cava manufactured with a blend of typical white grape varieties (Xarello: Macabeo: Parellada) has been investigated. The wines were industrially manufactured in a cellar, and the concentrations of outstanding nitrogen compounds and 23 target volatile compounds belonging to different chemical classes were determined in the base wines and in the corresponding Cava wines after 9, 12, 15 and 18 months of aging on lees. After the application of multivariate statistical analysis, the results showed the large effect of the variety employed in the manufacture of Cavas compared to the changes in wine composition due to the aging time. Depending on the composition, Trepat and White Cava wines were more similar than those manufactured with the variety Monastrell. However, the sensory study showed that the two rosé Cava wines had good sensory attributes and even slightly better foam characteristics than the white ones. The sensory study highlighted for the first time the adequacy of using Monastrell red grape variety to manufacture rosé sparkling wines.     

Crystallization and demineralization phenomena in stabilized white mold cheese

Stabilized white mold cheese is a commercially important variant of traditional white mold cheese (sometimes called bloomy rind cheese) that has an extended shelf life compared with the traditional permutation. The objectives of this observational study were to document mineral element movements and the development of a pH gradient in stabilized white mold cheese, and to use novel crystallographic techniques to identify crystals that form in the rind of this cheese. Cheeses from 3 separate batches were collected from a commercial supplier at d 1, 4, 10, 14, and 18 of aging and analyzed in a randomized block design. Samples from the center and rind of each cheese were analyzed for calcium, magnesium, phosphorus, sodium, and moisture content. The effect of location within the cheese wheel was significant for all effects, whereas the effect of aging time was significant for all effects except sodium content. The interaction between location within the cheese and aging time was significant for all effects. Using powder x-ray diffractometry, the crystals that formed in the rind during aging were identified as brushite (CaHPO₄ · 2H₂O). The accumulation of mineral elements in the rind resulted in a substantial decrease in calcium, magnesium, and phosphorus in the center. After 18 d, calcium, magnesium, and phosphorus in the center had decreased by 26.4, 14.8, and 12.1%, respectively, compared with the first day of aging. The observations in the present study represent the first definitive identification of crystals in the rind of a white mold cheese. The use of novel crystallographic techniques in the present study lays the groundwork for the use of this technology in future investigations of mineral element diffusion phenomena in surface-ripened cheese.     

宰后成熟过程中猪肉保水性的变化

以三元猪背最长肌为研究对象,在第4、8、12、16、20、24、28、32和36 h分别检测蒸煮损失率、滴水损失率、贮藏损失率、剪切力值和pH值的变化情况,研究宰后成熟过程中猪肉保水性的变化规律。结果表明,蒸煮损失率呈先升高后降低的趋势,在第20 h蒸煮损失率达到最大值32.80%;贮藏损失率和滴水损失率呈先下降后上升再下降的趋势;剪切力值在4~12 h内显著性上升（p<0.05）,且在12 h达到最大62.29 N;pH值呈整体先下降后上升再下降最后趋于稳定的变化趋势;其中,成熟时间与剪切力值呈显著负相关（p<0.01）,pH值与蒸煮损失率呈极显著负相关（p<0.01）,滴水损失率与贮藏损失率呈较高的相关性（p<0.01）。综合指标,猪肉在宰后成熟36 h内保水性有先变弱后增强的趋势,在12~16 h内进入僵直高峰点,随后进入解僵成熟期。该研究结果可为后续深入研究宰后成熟过程中猪肉嫩度变化规律及机理提供基础指标和参考依据。     

Effect of Short Ageing on Lees on the Mannoprotein Content,Aromatic Profile,and Sensorial Character of White Wines

In Albariño white wines, aging of wines on lees is a technique not used or only used empirically by some producers to obtain a distinctive character in the final wine. This study analyzes the influence of a short aging on lees on the chemical and sensorial parameters of this young white wine. Albariño grape must was inoculated with a locally selected yeast (Saccharomyces cerevisiae 1) and the effect of a short aging on lees was studied during different times (10, 20, 30, 40, and 50 d). Mannoprotein content and the aromatic profile were determined and a sensorial analysis of the wines was conducted. Results showed that aging time was correlated with the concentration of some key aroma compounds and mannoproteins in Albariño wines. The best sensorial character was obtained in wines aged 20 d on lees. Further aging times decreased the sensorial quality of Albariño wine and modified its volatile profile and mannoprotein concentration.     

基于深度学习的籽棉中异性纤维检测方法

针对籽棉图像阴影多、常规图像处理方法难于识别的问题,以去除棉叶、棉壳等有机杂物的籽棉为样本,将不同颜色、形状、尺寸的12种常见异性纤维和籽棉样本随机地分布在运转中的传送带上,采用线扫描相机获得发光二极管（LED）照明的籽棉图像520张,“LED+线激光”双光源照明的籽棉图像1 148张。然后采用一种由13个卷积层、13个采样层和4个池化层构成的Faster RCNN深度学习人工神经网络,对 2 种成像方法获得的籽棉图像进行基于人工智能的网络训练,再进行异性纤维检测验证。实验数据表明,LED照明和“LED+线激光”双光源照明条件下,籽棉图像中的异性纤维的检出率分别达到了90.3%和86.7%,特别是LED照明条件下对白色异性纤维进行识别,其识别率由5.9%提升到了90.3%。     

基于激光线结构光的羊毛中白色污杂物检测

分别采用LED、LED+激光线结构光和单独使用激光线结构光3种照明方式,利用A601 basler黑白相机获取白色羊毛背景上的典型白色污杂物的图像,并根据图像直方图分布对不同成像方法的检测性能进行了分析.实验结果表明:利用激光线结构光的照明方式获取到的图像的直方图呈明显的双峰结构分布,能够对羊毛中白色污杂物进行有效检测.经测试,采用激光线结构光的照明方式对与羊毛质地呈明显差异的白色污杂物检测效果良好.