大环Schiff碱化合物的合成、表征及其荧光活性研究

含乙酰丙酮类大环Schiff碱化合物一般都具有良好的荧光活性．采用模板合成法,用对苯二胺与乙酰丙酮反应合成得到的Schiff碱配体（H2L）与烷基二胺（即1,2-乙二胺,1,3-丙二胺,1,4-丁二胺）反应合成了3种新型大环Schiff碱化合物,通过元素分析,^1H NMR,IR,MS,UV,摩尔电导等手段对合成得到的化合物进行了组成和结构表征,同时在DMF溶液中对大环Schiff碱锌（Ⅱ）配合物的荧光活性进行了初步研究．     

Stabilization of All-trans-retinol by Cyclodextrins: A Comparative Study Using HPLC and Fluorescence Spectroscopy

Purpose: To formulate preparations incorporating cyclodextrins (CDs) which could be used for direct delivery to the retina of vitamin A (all-trans-retinol), while also protecting it from degradation in the aqueous environment. Vitamin A supplementation is being considered for treatment of several ophthalmic diseases characterised by progressive photoreceptor degeneration. Methods: The complexation between vitamin A and ten cyclodextrins, Captisol^®(sulfobutyl ether-7--cyclodextrin), hydroxypropyl--CD, 2-hydroxypropyl--CD, -CD, hydroxypropyl--CD, hydroxypropyl--CD, -CD, methyl--CD,Heptakis-(2,6-di-O-methyl)--CD andHeptakis-(2,3,6-tri-O-methyl)--CD,was investigated using bothhigh sensitivity fluorescence spectrometry and HPLC (high pressure liquid chromatography). Samples of retinol-CD complexes in phosphate buffer, pH 7.4 were analysed for up to 72 hours. Optimum conditions for formation of the Captisol-retinol complexes were investigated. Results: Using spectroscopic measurements and HPLC, the complexes formed between ten cyclodextrins and all-trans-retinol were evaluated. The results indicate that all cyclodextrins tested were able to form inclusion complexes as shown by the fluorescence signals which are considerably larger than those obtained in the absence of cyclodextrin. Only minimal degradation of retinol over 48 hours was observed with three of these cyclodextrins. Captisol was able to stabilise all-trans-retinol for up to 72 hours, as shown by HPLC, and the optimum ratio of Captisol to retinol was determined to be 50 to 1. Addition of glutathione and decrease in pH did not improve stability of the complex. Conclusions: This survey suggests that Captisol and other cyclodextrins could be used to stabilise and solubilise vitamin A in aqueous media and this establishes the basis for an ocular Captisol-retinol drug delivery system now under development in our laboratory.     

基于傅里叶变换红外光声光谱的包膜控释肥料聚合物膜疏水性的表征

以不饱和有机硅改性的丙烯酸酯为基材,在不同条件下制备了30种水基聚合物包膜控释肥料模型膜,测定了模型膜的溶胀度及模型膜的傅里叶变换红外光声光谱.分别以红外光声光谱和溶胀度为自变量和因变量进行简单相关分析,同时也构建了偏最小二乘模型,并利用该模型对模型膜的疏水性进行预测.结果表明,聚合物模型膜具有明显不同的疏水性,其红外光声光谱具有相似的吸收特征,但不同吸收带的相对强度发生明显改变;常用的简单相关分析无法实现模型膜疏水性的预测,表明模型膜的疏水性与谱区更多的特征峰相关;基于偏最小二乘法的多元校正分析具有很好的预测能力,模型的校正系数(R2)为0.9864,校正标准误差为0.70%,验证标准误差为1.92%.此模型可用于模型膜疏水性的预测.本方法样品用量少,测定快速,操作简便且可实现原位测定,为控释肥料包膜材料的研制提供新的手段.     

A Simultaneous,Laser-Excited Fluorescence,Photoacoustic, and Two-Photon Photoionization Detector for Liquid Chromatography

Abstract

A laser-excited windowless flow cell has been developed for simultaneous fluorescence, photoacoustic, and two-photon photoionization detection of aromatic compounds in HPLC eluents. Sensitive three-mode detection of acridine, naphthalene, 7,8-benzoflavone, N-ethylcarbazole, and anthracene in 70/30 V/V acetonitrile/water is demonstrated with conservative detection limits in the nanogram range and below.     

A Crystalline Quartz,Laser-Excited Fluorescence,Photoacoustic, and Two-Photon Photoionization Detector for HPLC

Abstract

A crystalline quartz flow cell has been developed for simultaneous fluorescence, photoacoustic effect, and two-photon photoionization detection of aromatic compounds in HPLC eluents. Excimer laser-excited three mode detection of naphthalene, 7,8-benzoflavone, N-ethylcarbazole, and anthracene in 70/30 v/v acetonitrile/water is exhibited. The flow cell is suitable for use with deoxygenated solvent systems and is orientation independent.     

Characterization of Refuse Derived Fuel Using Thermogravimetric Analysis and Chemometric Techniques

An approach for characterization of refuse derived fuel (RDF) using thermogravimetry and chemometric techniques was developed. For this purpose, a series of samples coming from lignocellulosic products (wood, cardboard, paper, newspaper) and plastics (polyethyleneterephthalate, high density polyethylene, polypropylene, polypropylene, nylon and polyvinylchloride), as well as their mixtures, were investigated by means of thermogravimetry (TG) in a temperature range between 25 and 800°C. The datapoints of TG diagrams (weight loss) were then subjected to principal component analysis in order to unravel similarities/ dissimilarities of the investigated samples. A classification was obtained according to their woody/petroleum derived origination. This classification was more evident if partial least square discriminant analysis was employed. Finally, a partial least square analysis was carried out for the determination of lignocellulosic content in the sample. The model was validated by application to samples with known mass fraction of lignocellulosic products. Finally, the model was applied to two RDF samples using fractions of their particle sizes from 1 mm to less than 0.032 mm, and the results were compared with their ultimate and proximate analysis.     

A Novel Green Synthesis of Silver Nanoparticles Using Gum Karaya: Characterization,Antimicrobial and Catalytic Activity Studies

Stable silver nanoparticles have been synthesized using gum karaya acting as both reducing and stabilizing agent without using any synthetic reagent. The reaction is performed using water, which is an environmentally safe solvent. This reaction was carried out in an autoclave at a pressure of 15 psi and 120 °C temperature by varying the time. The influence of different parameters such as time, change of concentration of silver nitrate and concentration of gum karaya on the formation of silver nanoparticles has been studied. The synthesized silver nanoparticles are characterized by UV–Vis spectroscopy, FTIR, XRD and TEM. UV–Vis analysis of the sample confirmed the formation of silver nanoparticles exhibiting a sharp peak at a wavelength of 420 nm. TEM micrographs showed the formation of well-dispersed silver nanoparticles of size 2–4 nm. The antimicrobial activity of silver nanoparticles stabilized in gum karaya is tested against Escherichia coli, Micrococcus luteus and is found to be possessing inhibiting property. The silver nanoparticles stabilized in gum karaya exhibited very good catalytic activity and the kinetics of the reaction was found to be pseudo first order with respect to the 4-nitrophenol.     

Measurement of A Two Layer Sample Using Pseudo Pulse Excited Photoacoustic Spectrometry

Abstract

To obtain surface layer thickness easily, a simple pseudo pulse excited photoacoustic spectrometric method was proposed. An argon ion laser was chopped mechanically to generate a pseudo pulse (pulse width; 6.6 ms, duty 1.67%), which was then led to a sample enclosed in photoacoustic cell. Two layer samples made of polymethyl methacrylate (PMMA) were used as model samples. The photoacoustic signal waveform observed showed a maximum from the negative edge of the pseudo pulse of the laser. The delay of the signal increased concomitant with the sample surface thickness. The delay time of the signal was calculated by a cross-correlation method. A linear relationship was obtained between the delay time of the photoacoustic signal from the input pseudo pulse and the surface transparent layer thickness in the range of 0–90 mm. The regression line between the film thickness x (cm) and the delay time was expressed with the thermal diffusivity of the film k, as follows; Δτ (s) = 1.16 × 10^?1 κ^?½ x + 0.006. Using this result, the method proposed was successfully applied to the measurement of the thickness for laminated polyethylene film on papers. The method proposed is simple and easy to perform without any modification of usual photoacoustic instrumentation.     

Sensitive Detection of Aromatic Molecules by Laser Photoacoustic Spectrometry: Signal Enhancement by Fluorescence Quencher

Highly sensitive detection of aromatic molecules has been investigated by pulsed laser excitation. A cylindrical cell surrounded by a piezoelectric transducer has improved the detection limit. Fluorescence quencher, CH₃NO, increased the photoacoustic signal of perylene up to three times and the signal-to-noise ratio by about 50%. Typical detection limits of pyrene and perylene were 0.4 ppb in hexane and 6.7 ppb in methanol with nitromethane, respectively.     

荧光探针技术在两亲分子有序组合体研究中的应用

荧光技术具有灵敏度高、可测量参数丰富、扰动小、无破坏性等优点,因而在两亲分子有序组合体的研究方面得到极为广泛的应用。本文介绍了国内外利用各种荧光探针技术测定两亲分子有序组合体的微极性、微粘度、动力学过程、聚集数等微观信息,并对具有表面活性剂结构的荧光探针做了简要介绍,最后对基于荧光探针技术的两亲分子有序组合体的研究进行了展望。     

A Study of the Antioxidant Effect of Flavonic Compounds for Preventing Lipid Oxidation by Using Fluorescence Spectroscopy

In this paper a study of the effect of flavonic compounds in preventing and/or reducing the membrane lipid oxidation due to free radical attack was performed by using fluorescence spectroscopy techniques. Lipid peroxidation was investigated by using liposomes-artificial membrane models, which were prepared by lipid hydration method. Their oxidation was performed with a 15-W ultraviolet germicidal lamp having wavelength radiation 253.7 nm. In the first series of experiments, the protective effect of two synthetic antioxidants (quercetin and caffeic acid) against free radicals was monitored, while in the second series two 70% hydroalcoholic extracts from blueberry and blackcurrant leaves was used. It was determined that natural antioxidants have a much higher antioxidant power against free radicals than synthetic compounds but they degrade after two hours of oxidation. Liposomes are better protected when using natural antioxidants, but their degradation is completed more quickly, than in the case of synthetic antioxidants.     

蝶呤类化合物的荧光性能研究

研究了蝶呤类化合物的天然荧光特性。着重考察了新蝶呤、生物蝶呤、黄蝶呤和蝶呤在 p H7.7磷酸盐缓冲溶液条件下的荧光光谱及各种因素对其荧光强度的影响。在最佳实验条件下 ,四种蝶呤类化合物的线性范围为 :蝶呤 0 .6～ 2 .8μg/m L,新蝶呤 0～ 2 .6μg/m L,生物蝶呤 0～ 2 .4μg/m L,黄蝶呤 0～ 6.0 μg/m L,检出限依次为 :4.2 9× 1 0 - 7g/m L,6.71× 1 0 - 8g/m L,5.79× 1 0 - 9g/m L和 1 .75× 1 0 - 8g/m L     

激光二极管激光诱导荧光检测器的研制

采用紫色激光二极管作为荧光检测器的激发光源,以普通光电倍增管作为光电转换装置,构建共聚焦光学结构的激光诱导荧光检测器。考察了物镜放大倍数、滤光片、光源电流和增益大小等条件对于仪器分析性能的影响,并用荧光胺和FITC衍生的氨基酸、罗丹明类染料、荧光素等物质对灵敏度进行了表征,得到该检测器对荧光胺衍生的亮氨酸的检出限为0.02nmol·L-1,对于罗丹明B和荧光素钠的检出限分别为9.46nmol·L-1和1.02nmol·L-1。该检测器相对文献报道的其它激发光源的检测器,在保持了低成本优势的同时还具有高灵敏度的优点,而且可用于多类染料标记物的分析检测。     

基于固相萃取的微量糖蛋白糖基化修饰表征技术的建立

结合自制亲水固相萃取富集柱和生物质谱鉴定技术,实现了糖基化蛋白质核糖核酸酶B的糖含量测定、糖基化位点确认、聚糖富集及结构表征,以及不同糖型相对丰度分析。结果表明:其糖含量8.47%,糖基化位点为34位的Asn,糖链主要为5种高甘露糖型结构(Man5-9GlcNAc2)。所建立的HILIC富集技术,有利于针对微量生物样本,如生物工程药物糖蛋白及重要功能糖蛋白,开展位点特异性糖链结构解析,为糖蛋白质的药效或功能研究提供线索。     

用循环伏安法和同步荧光光谱技术研究肌红蛋白的电化学行为

用循环伏安法和同步荧光光谱技术研究了肌红蛋白的电化学行为，实验结果表明，高铁肌红高蛋白分子至少存在的一个可调节分子构象变化的氧分子，而且长时间通入高纯氮气可以除掉高铁肌红蛋白分子内的这个氧，当高肌红蛋白分子内的氧被彻底除去后，用循环伏安法可以观察到肌红蛋白在三氧化二铟电极上的准可逆的电学反应，同步荧光光谱实验表明，高铁肌红蛋白在彻底除氧后，分子构象发生了变化，而且这种构象变化是可逆的。     

Carbon Black Detector,A Novel Approach to Visible Spectroscopy of Liquids Using Photoacoustic Detection

Abstract

A simple and reproducible method of recording visible spectra of solutions using photoacoustic spectrometry and carbon black as a thermal detector is introduced. Light intensity is proportionally measured by carbon black detector, a microphone system and a simple cell compartment placed after monochromator for liquid samples. Exact match with the absorption spectra is found with certain standard solutions. Aqueous solutions of Cr(III), KMnO₄, disodium fluorescein and chlorpromazine semiquinone cation radicals are tested.     

Crystallization of Silica Xerogels: A Study by Raman and Fluorescence Spectroscopy

Pure and europium doped silica xerogels were annealed at 1050°C to obtain full densification, and at 1300°C to induce crystallization. Raman spectroscopy, time resolved selective luminescence and lifetime measurements were performed on glassy and crystallized samples. We discuss the differences between the Raman spectra of the xerogel annealed at 1050°C and those of a commercial silica. The typical Raman structures of -crystobalite are evident for the 1300°C annealed samples, but a glassy phase coexists, indicating an incomplete crystallization. Fluorescence measurements give information on the environment of the Eu³⁺ ions in the glassy and crystallized sample.     

Geographical Characterization of Greek Olive Oils Using Rare Earth Elements Content and Supervised Chemometric Techniques

Different ANNs models [Multi-layer Perceptrons (MLPs) and Radial Basis Function (RBF)] were developed and evaluated for the discrimination of olive oils produced in four Greek regions according to their geographical origin. For this purpose, ninety-seven samples were analyzed for 10 rare earth elements (REE) by ICP-MS. Moreover, two additional supervised techniques, discriminant analysis (DA) and classification trees (CTs), were applied to the same set for the data pre-treatment and for comparison purposes. In addition, two approaches were used for models' training and evaluation: the classical random choice of samples for the learning data set and an innovative one, which used the two linear discriminant functions (LDFs) of the preceding DA to choose the most representative learning sample set. The results were very satisfactory for the new ANNs classifiers. Over-fitting phenomena were overcome and the prediction ability was 73%, as evaluated by an independent test sample set. The results are encouraging for the ANNs efficiency even in demanding data bases, as the one under consideration.

[Supplementary materials are available for this article. Go to the publisher's online edition of Analytical Letters for the following free supplemental resources: Additional figures and tables.]     

Fabrication of Dye-sensitized Solar Cells and Fluorescence Quenching Study Using Thiophene Based Copolymers

Photovoltaic performance of dye sensitized solar cells fabricated with a commercially available thiophene based copolymer was investigated. Poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(bithiophene)], a highly soluble polythiophene, was used as a sensitizer. An open-circuit voltage of 0.64 V and a short-circuit current density of 0.36 mA/cm² were measured. The incident photon to current conversion efficiency for the polymer was measured. Fluorescence from the other polythiophene, poly(3,3′-didodecyl quarter thiophene) was found to be quenched when blended with phenyl C₆₁ butyric acid methyl ester (PCBM) (1:1 wt ratio), indicating the charge transfer from the conjugated polymer to PCBM.