Geographic Characterization of Leccinum rugosiceps by Ultraviolet and Infrared Spectral Fusion

Leccinum rugosiceps is an edible mushroom belonging to genus Leccinum of Boletaceae. Its fruiting bodies are richer in nutrients than many vegetables and fruit. The model of support vector machine was established for the discrimination of L. rugosiceps from regions based on rapid and low-cost ultraviolet and infrared spectroscopies. The mid-level data fusion was performed by support vector machine. Compared to a single spectroscopic technique, mid-level data fusion provided higher accuracy by selecting the most significant variance from data matrixes based on partial least squares discriminant analysis. The accuracy of the classification of samples in the calibration and test sets were 85.00 and 94.74%, higher than separate measurements by ultraviolet or infrared spectroscopy. This approach has applications for authentication and quality assessment of L. rugosiceps.     

3类高关注紫外线吸收剂的前处理与检测技术研究进展

紫外线吸收剂是一种具有强烈吸收紫外线作用的光稳定剂,会对生态环境以及人体健康造成危害,国内外许多国家已制定相关法规限制其使用。该文综述了近几年来国内外关于二苯甲酮类、三嗪类和苯并三唑类3类紫外线吸收剂检测的研究现状,分别对样品前处理与检测技术进行了详细介绍,并对其研究发展趋势进行了展望。     

离子色谱法-间接紫外检测离子液体中三种含氟酸根阴离子

建立了离子色谱-间接紫外检测法同时分析离子液体中的三氟乙酸根(CF3COO-)、四氟硼酸根(BF4-)和三氟甲烷磺酸根(CF3SO3-)的方法。用Shodex IC NI-424阴离子交换柱作为分离柱,探讨了影响上述三种离子保留和检测的因素及其保留规律。最终选用色谱条件为:以1.75 mmol·L-1邻苯二甲酸-1.68 mmol·L-1三(羟甲基)氨基甲烷为淋洗液,柱温45℃,流速1.0 m L·min-1,UV检测波长设定在265 nm。在此条件下,可实现上述三种阴离子的同时分析,且色谱峰形良好。所测阴离子的检出限(S/N=3)为0.39~1.57 mg·L-1,保留时间和峰面积的相对标准偏差(n=5)均在1%以下。将此方法应用于测定离子液体中的三氟乙酸根、四氟硼酸根及三氟甲烷磺酸根,加标回收率为99%~102%。该方法简单、准确、可靠,具有较好的实用性。     

NaGdF4:Eu3+的结构和VUV荧光性质

利用水热方法合成了纯度较高的六方结构的ＮaGdF4,在氧气存在条件下950℃加热处理可以使其转变为CaF2型立方结构,在真空紫外光激发下,六方结构的NaGdF4:Eu^3 中的Gd^3 离子吸收一个光子,并将能量分两步传递给Eu^3 离子,发生双光子发射,立方结构的NaGdF4:Eu^3 中存在有一定量的氧离子取代缺陷,使Gd^3 离子4f-5d跃迁移到177nm附近,这与惰性气体放电产生的真空紫外波长一致。     

Spectroscopy Investigation on Conformational Transition of Tea Glycoconjugate from Green Tea

The conformational transition of a new glycoconjugate, tea glycoconjugate (TGC), was investigated by spectroscopy techniques including circular dichroism (CD) and ultraviolet (UV) spectroscopy. The solution behaviors of TGC in the mediums of different temperature, pH value, and ions were compared. Results showed that the native conformation of TGC was partially ordered. The CD value and UV absorbance of TGC altered with the change of pH value, temperature, the addition of ions, and also accompanied order-disorder transition. Especially the conditions with temperature higher than the glass transition temperature (Tg=62℃), higher pH value or lower pH value will have the most impact on the conformation of TGC, which will destroy the hydrogen bonds between the TGC molecules. The results indicated that the outside factors play important roles on the stability of the conformation of TGC.     

牛血清白蛋白与十二烷基硫酸钠作用的机理

利用电动势法得到了牛血清白蛋白(BSA)与十二烷基硫酸钠(SDS)相互作用的结合等温线. 通过四阶导数紫外光谱法和荧光光谱法研究了相互作用过程中芳香族氨基酸残基微环境极性的变化. 通过研究发现, 随着SDS浓度的逐渐增大, SDS在BSA上的平均结合数(v)逐渐增大, 色氨酸(Trp)残基所处微环境的极性在减弱后保持基本不变, 酪氨酸残基所处微环境的极性在明显增强后稍有减弱, 苯丙氨酸残基所处微环境的极性略有增强. 结果表明, 当v由0增大到14时, SDS主要结合在BSA的Trp-213附近并逐渐形成聚集体, 从而诱导BSA由结构域ⅡA 开始逐渐展开. 此后, SDS呈正协同作用的特点与BSA 结合, v急剧增大. 当v约为302 时, SDS在BSA上的结合基本达到饱和, BSA的构象趋于稳定.     

离子对色谱法同时分离测定吡啶及咪唑离子液体阳离子

建立了用紫外检测的反相离子对色谱梯度淋洗同时分离测定4种吡啶离子液体阳离子和5种咪唑离子液体阳离子的方法。实验采用ZORBAX Eclipse XDB-C18反相色谱柱,以离子对试剂水溶液(用柠檬酸调节pH值)+乙腈为流动相,考察了离子对试剂种类和浓度、乙腈浓度和色谱柱温度对保留的影响,探讨了相关保留规律,确定最佳色谱条件为:流速1.0 mL/min、柱温30℃,以1.0 mmol/L庚烷磺酸钠水溶液(pH 4.0)-乙腈为淋洗液进行梯度洗脱。在此条件下,4种吡啶阳离子和5种咪唑阳离子在15 min内达到基线分离。检出限(S/N=3)为0.31～0.54 mg/L,峰面积的相对标准偏差为0.10%～0.75%。将该方法用于实验室合成的离子液体样品分析,加标回收率为94%～98%。该方法准确、可靠,具有较好的实用性。     

In气氛下晶体生长对Mg掺杂p-Al_xGa_(1-x)N激活能的影响

Ⅲ-Ⅴ族氮化物宽禁带半导体材料体系中,普通方法生长的p型外延层电导率一般都很低,成为了制约器件性能提高的瓶颈。在p-AlxGa1-xN材料中,Mg受主的激活能较大,并且随Al组份增加而增大。通过在p-AlxGa1-xN材料生长过程中引入三甲基铟(TMIn),发现能有效地降低AlxGa1-xN材料中受主态的激活能。为研究不同In气氛下生长的p-AlxGa1-xN材料的性质,在使用相同二茂基镁(CP2Mg)的情况下,改变TMIn流量,生长了A,B,C和D四块样品。X射线衍射(XRD)组份分析表明:在1100℃下生长AlxGa1-xN外延层时,In的引入不会影响晶体组份。利用变温霍尔(Hall)测试研究了p-AlxGa1-xN材料中受主的激活能,结果表明:In气氛下生长的外延层相比无In气氛下生长的外延层,受主激活能明显降低,电导率显著提高。采用这种方法改进深紫外发光二极管(LED)的p-AlxGa1-xN层后,LED器件性能明显提高。     

自由大气紫外光学通信的研究

本文对紫外日盲区光谱在近距离、保密通信中的应用进行了探讨 ,并建立了紫外光学通信原理实验系统。所描述的系统是以日盲区紫外光作为信息载体的 ,用被调制的低压汞蒸汽紫外放电灯作为发射器件 ,以日盲型滤光片和光电倍增管或日盲型紫外光电倍增管作为接收器件 ,以达到在任何时间和在任何气候下完成窄频带模拟或低速数字信号的传输。由于近地表大气臭氧层的吸收 ,所以传输距离被限制在一个较小的范围内 ,构成了短距离的、秘密的、安全的和抗干扰的通信系统 ,并且不需要传统意义上的天线。由于地球大气上层臭氧的吸收作用 ,阳光中的日盲区 (2 0 0～ 2 80 nm)辐射几乎无法到达地球表面 ,因此 ,采用这个波段的光学通信系统几乎不会受到太阳光的干扰。典型的大气臭氧浓度高度分布大约在距地表 2 5 km处达到最高值 ,在海平面处有一个较低的值。相对较低的浓度值来说 ,虽然紫外辐射传输有限 ,但是具有足够远的距离 ,同时可达到安全、秘密和抗干扰的目的     

Prospective study on observations of γ-ray sources in the Galaxy using the HADAR experiment

The High Altitude Detection of Astronomical Radiation (HADAR) experiment is a refracting terrestrial telescope array based on the atmospheric Cherenkov imaging technique. It focuses the Cherenkov light emitted by extensive air showers through a large aperture water-lens system for observing very-high-energy γ-rays and cosmic rays. With the advantages of a large field-of-view (FOV) and low energy threshold, the HADAR experiment operates in a large-scale sky scanning mode to observe galactic sources. This study presents the prospects of using the HADAR experiment for the sky survey of TeV γ-ray sources from TeVCat and provids a one-year survey of statistical significance. Results from the simulation show that a total of 23 galactic point sources, including five supernova remnant sources and superbubbles, four pulsar wind nebula sources, and 14 unidentified sources, were detected in the HADAR FOV with a significance greater than 5 standard deviations (σ). The statistical significance for the Crab Nebula during one year of operation reached 346.0 σ and the one-year integral sensitivity of HADAR above 1 TeV was ~1.3%–2.4% of the flux from the Crab Nebula.