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。     

气相色谱-质谱法测定水体中5种典型有机紫外防晒剂

建立了水体中5种典型有机紫外防晒剂甲氧基肉桂酸乙基己酯（ethylhexyl methoxycinnamate,EHMC）、二苯酮-3（benzophenone-3,BP-3）、4-甲基苄亚基樟脑（4-methylbenzylidene camphor,4-MBC）、奥克立林（octocrylene,OC）和胡莫柳酯（homosalate,HMS）的气相色谱-质谱检测方法。对HMS、BP-3衍生化条件进行了系统的优化。以100 μL双（三甲基硅烷基）三氟乙酰胺（N,O-bis（trimethylsilyl） trifluoroacetamide,BSTFA）为衍生化试剂,在100 ℃下反应100 min。水样固相萃取选用Oasis HLB萃取柱（0.5 g）,洗脱溶剂为乙酸乙酯-二氯甲烷（1：1,v/v）,水样pH 3~5。该方法对5种化合物的检出限范围为0.5~1.2 ng/L,定量限范围为1.4~4.0 ng/L。最佳实验条件下,加标水样回收率为87.85%~102.34%,相对标准偏差（n=3）均小于5%。该方法成功地应用于昆明市第一污水厂进出口水样中目标物质的分析。     

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。     

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.     

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。     

Deep‐ultraviolet laser ablation electrospray ionization mass spectrometry

A 193‐nm wavelength deep ultraviolet laser was used for ambient laser ablation electrospray ionization mass spectrometry of biological samples. A pulsed ArF excimer laser was used to ablate solid samples, and the resulting plume of the desorbed material merged with charged electrospray droplets to form ions that were detected with a quadrupole time‐of‐flight mass spectrometer. Solutions containing peptide and protein standards up to 66‐kDa molecular weight were deposited on a metal target, dried, and analyzed. No fragmentation was observed from peptides and proteins as well as from the more easily fragmented vitamin B₁₂ molecule. The mass spectra contained peaks from multiply charged ions that were identical to conventional electrospray. Deep UV laser ablation of tissue allowed detection of lipids from untreated tissue. The mechanism of ionization is postulated to involve absorption of laser energy by a fraction of the analyte molecules that act as a sacrificial matrix or by residual water in the sample.     

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。     

超声萃取-高效液相色谱法同时测定人造革中7种苯并三唑类紫外线吸收剂含量

建立了超声萃取-高效液相色谱法(HPLC)同时测定人造革中7种苯并三唑类紫外线吸收剂UV-P、UV-326、UV-327、UV-329、UV-350、UV-320和UV-328含量的方法。该方法以甲醇为萃取溶剂,超声萃取人造革中的苯并三唑类紫外线吸收剂,萃取液经处理后直接进行HPLC分析,外标法定量。在信噪比(S/N)=3的条件下,UV-P、UV-326、UV-327、UV-329、UV-350的检出限均为0.05mg/kg,UV-320、UV-328的检出限均为0.10 mg/kg。在3个不同加标浓度水平下,各组分的平均加标回收率为88.19%~98.32%,相对标准偏差(RSD)为0.61%~3.74%。该方法简便快捷、灵敏度高,可用于人造革中苯并三唑类紫外线吸收剂的测定。采用该方法对市售人造革样品进行测定,结果在6个样品中检出了不同浓度水平的UV-P和UV-329。     

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.     

Energy-Efficient Optimization for Energy-Harvesting-Enabled mmWave-UAV Heterogeneous Networks

Energy Harvesting (EH) is a promising paradigm for 5G heterogeneous communication. EH-enabled Device-to-Device (D2D) communication can assist devices in overcoming the disadvantage of limited battery capacity and improving the Energy Efficiency (EE) by performing EH from ambient wireless signals. Although numerous research works have been conducted on EH-based D2D communication scenarios, the feature of EH-based D2D communication underlying Air-to-Ground (A2G) millimeter-Wave (mmWave) networks has not been fully studied. In this paper, we considered a scenario where multiple Unmanned Aerial Vehicles (UAVs) are deployed to provide energy for D2D Users (DUs) and data transmission for Cellular Users (CUs). We aimed to improve the network EE of EH-enabled D2D communications while reducing the time complexity of beam alignment for mmWave-enabled D2D Users (DUs). We considered a scenario where multiple EH-enabled DUs and CUs coexist, sharing the full mmWave frequency band and adopting high-directive beams for transmitting. To improve the network EE, we propose a joint beamwidth selection, power control, and EH time ratio optimization algorithm for DUs based on alternating optimization. We iteratively optimized one of the three variables, fixing the other two. During each iteration, we first used a game-theoretic approach to adjust the beamwidths of DUs to achieve the sub-optimal EE. Then, the problem with regard to power optimization was solved by the Dinkelbach method and Successive Convex Approximation (SCA). Finally, we performed the optimization of the EH time ratio using linear fractional programming to further increase the EE. By performing extensive simulation experiments, we validated the convergence and effectiveness of our algorithm. The results showed that our proposed algorithm outperformed the fixed beamwidth and fixed power strategy and could closely approach the performance of exhaustive search, particle swarm optimization, and the genetic algorithm, but with a much reduced time complexity.