Laser ablation parameters of atherosclerotic arteries

Summary The threshold of atherosclerotic plaque ablation in water by the XeCl laser radiation was measured to be of (1.5±0.2) J/cm². Within the simple thermal model this value corresponds to the mean temperature of about 373 K in the irradiated volume as for other angioplasty lasers. Time-of-flight probing of ablation in air by the XeCl and CO₂ lasers revealed microsecond lifetimes of ablated volumes that confirm the mechanism of explosive boiling of superheated tissue water. So the local temperature must be about 582 K which can be due to inhomogeneous light distribution and absorption. The short lifetime leads to the absence of heat diffusion and, hence, to the ablative character of tissue destruction.     

非接触二次色散法测量人体血糖的初步研究

提出了一种测量血糖浓度的新方法——二次色散法，此方法采用低相干干涉仪来测量时间相干干涉信号，通过傅里叶变换和多项式拟合获得二次色散。初步测量了三种不同浓度的糖溶液在0．55μm到0．8μm之间的二次色散，实验结果发现随着血糖浓度的增加，二次色散也随之增加。研究证明该方法是一种潜在的无接触、无伤害在线探测人体血糖浓度的方法。为设计一种非接触、无伤害在线探测人体血糖浓度的光学医疗仪器奠定基础。最后讨论了采用本方法尚需改进的问题和进一步的工作。     

Validation of two analytical methods for the determination of ochratoxin A by reversed-phased high-performance liquid chromatography coupled to fluorescence detection in musts and sweet wines from Andalusia

Some Spanish sweet wines are made from raisins, grapes dried by direct exposure to the sun after picking. This drying process can encourage ochratoxin A (OTA) formation. OTA is a mycotoxin formed by several fungi. It has been linked to nephropathy in humans, and may have a long half-life in humans. The aim of this study is to develop and to apply two procedures for the analysis of OTA in grape musts (during the raisining process) and sweet wines, respectively. Reversed-phase high-performance liquid chromatography (RP-HPLC) coupled to fluorescence detection (FLD) was employed in both analytical methods. In grape must, the method involves the direct injection of the sample in a HPLC-FLD system without any kind of prior clean-up procedure. The complexity of the sweet wine samples requires a solid-phase extraction (SPE) clean-up on a C18 column which enables the OTA to be isolated from the matrix. The methods used were statistically validated. The validation also included the comparison of the slopes of the curve obtained with standards and the regression curves obtained by the addition of a standard. Two different studies of standard additions were conducted. One method was validated without sample preparation and it was applied to must samples. The other method was validated with SPE extraction and it was applied to sweet wine samples. Recovery was always better than 89.69%. The limit of detection (S/N = 3) and limit of quantification (S/N = 10) were established at 0.22 and 0.77 μg l⁻¹, respectively. In general, the analytical data obtained provided good results at the sub-μg l⁻¹ concentration level.     

Radiation‐induced migration of additives in PVC‐based biomedical disposable devices Part 2. Surface analysis by XPS

Extruded parts of non‐sterilized and β‐irradiated (25 and 50 kGy) plasticized poly(vinyl chloride) (PVC) used for disposable medical devices have been studied to investigate the effect of sterilization on surface chemical composition. The polymer surfaces were analysed using angle‐resolved x‐ray photoelectron spectroscopy. The inner surface of the blood tubing lines showed a fairly smooth surface both before and after sterilization, so a laterally homogeneous surface can be assumed for XPS analysis. The XPS survey spectra exhibited no signals besides carbon, chlorine, oxygen and calcium. Detailed analysis of the regions showed the C 1s, Cl 2p and O 1s signals to be multi‐component, presenting signals of the PVC, the plasticizer and the other additives. Binding energies remained constant irrespective of β‐radiation dosage, but the amount of chlorine component at 198.4 ± 0.1 eV (associated with modified PVC) decreased with sterilization dosage. Angle‐resolved XPS revealed that this component is located at the outermost surface of the polymer. It can be hypothesized that the production processes themselves (extrusion and/or injection molded) already induce modifications of the polymer surface and also lead to surface segregation of the plasticizer. During the subsequent thermal sterilization of the polymer dehydrochlorination continues but, because of the very short time required by the β‐irradiation technology to sterilize devices, the atmospheric oxygen is unable to diffuse into the irradiated material, thus inhibiting further side‐degradation of the materials, such as thermo‐oxidative degradation. Copyright © 2003 John Wiley & Sons, Ltd.     

Fluorometric quantification of total d-gluconate by a flow-injection system using an immobilized-enzyme reactor

A method for the quantification of total d-gluconate by flow-injection analysis was developed using an immobilized-enzyme reactor and fluorescence detection. d-Gluconate was quantified using co-immobilized gluconate kinase (GK) and 6-phosphogluconate dehydrogenase (PGDH) reactor. d-Gluconate was phosphorylated to 6-phospho-d-gluconate by GK in the presence of ATP, and then the 6-phospho-d-gluconate produced was oxidized by PGDH with NADP⁺. The NADPH produced by the GK-PGDH reactor was monitored fluorometrically at 455 nm (excitation at 340 nm). A linear relationship between the responses and concentrations of d-gluconate was obtained in the ranges of 1.0 × 10⁻⁶-1.6 × 10⁻⁴ M. The relative standard deviation for 10 successive injections was 0.57% at the 0.1 mM level. This analytical method was applied to the quantification of d-gluconate in honeys, vinegars and noble rot wines, and the results showed good agreement with those obtained using the conventional F-kit method.     

Effect of freeze-dried immobilized cells on delignified cellulosic material in low-temperature and ambient-temperature wine making

In this article, were port on wine making by freeze-dried immobilized cells on delignified cellulosic material for ambient and low temperatures. Biocatalyst supported by freeze-dried delignified cellulosic (FDC) material recovered after the first repeated-batch fermentations the fermentation efficiency and startup, which become about equal to those of biocatalyst supported by wet delignified cellulosic material. The FDC biocatalyst was suitable for wine making at low temperatures (5–15°C), and produced wine of 12% alcoholic degree, with the main volatiles contained in the wine and reduced by a decrease in temperature. The fermentation efficiency was not affected by total acidity of must, while an increase in initial Be density improved percentages of higher alcohols and ethylacetate. The quality of the wine was validated by a preliminary taste test to be in the range of acceptable to excellent.     

Comparative analysis of volatile compounds of ‘fino’ sherry wine by rotatory and continuous liquid-liquid extraction and solid-phase microextraction in conjunction with gas chromatography-mass spectrometry

Different headspace solid-phase microextraction (HS-SPME) methods have been selected and applied to the analysis of volatile compounds in ‘fino’ sherry wine by gas chromatography-mass spectrometry. A method based on rotary and continuous liquid-liquid extraction (LLE) for analysis of these same compounds has been optimised. The best conditions to extract this type of compounds using SPME and LLE were determined and both methods were validated. Both methodologies show adequate detection and quantitation limits, and linear ranges for correctly analysing these compounds. The recoveries obtained were close to 100%, with good repeatability values. The analytical and procedural advantages and disadvantages of these two methods have been compared. In general, SPME presented higher sensitivities. Both analytical methods were used to analyse five samples of ‘fino’ sherry wine supplied by different producers. No significant differences were found between the techniques at a significance level of 5%. The regression coefficients (r²) for analysis using LLE and SPME exceeded 0.94 for all compounds. The LLE procedure is a method with high repeatability and has the possibility of simultaneous extraction of several samples (up to 12), however the SPME technique is a solvent-free method presenting major advantages, such as small sample volume and higher sensitivity and simplicity.     

葡萄酒分析中模式识别方法的研究：Ⅱ.原汁含量的多元判别分析

本实验采用常规分析方法，分析了１８个不同含汁量酒样的乙醇，总酸，挥发酸，固定酸，干浸出物，ｐＨ值，灰份，灰份碱度，总酚，甘油，钾，钠，镁，干浸出物与甘油比，Ｑ值，修正干浸出物共１７个变量。采用计算机模式识别技术，利用逐步判别方法，得出了葡萄酒中原汁含量种逐步别方法的判别函数和回判结果。     

Separation of Structurally Related Anthocyanins by MEKC

Summary A method based on micellar electrokinetic chromatography has been developed for the simultaneous separation of six anthocyanins (malvidin-3,5-diglucoside, malvidin-3-glucoside, malvidin-3-galactoside, pelargonidin-3-glucoside, cyanidin-3,5-diglucoside, cyanidin-3-galactoside). Optimum selectivity was achieved in the buffer 30 mM phosphate + 400 mM borate-TRIS, pH=7.0 supported with 50 mM sodium dodecylsulphate. High content of borate was essential mainly for the separation of diastereomeric pair malvidin-3-glucoside-malvidin-3-galactoside. The calibration dependencies exhibit good linearity in the ranges of concentration 10–100 g mL^–1 for diglycosylated and 25–100 g mL^–1 for monoglycosylated derivatives (R² = 0.9711–0.9989). The optimized method was applied to a sample of wine grape skin extract. Malvidin-3-glucoside was identified as main anthocyanin colorant in this sample.