Ti/TiO<Subscript>2</Subscript> nanotube array electrode as a new sensor to photoelectrocatalytic determination of ethylene glycol

The photoelectrocatalytic oxidation behaviour of ethylene glycol (EG) was studied in the present work using the TiO₂-modified Ti foil (Ti/TiO₂) electrode. The Ti/TiO₂ nanotube array (Ti-NTA) electrode was prepared by anodizing of the Ti foil in the HF aqueous solution (0.2% v/v). The anodization was conducted in the constant 30 V for 2 h, and then the as-prepared Ti-NTA electrode was calcinated at 50 ^° C for 2 h. The surface morphology of Ti- NTA electrode was studied using scanning electron microscopy images. For EG determination, the photocurrent of EG (EG oxidation current in the UV irradiation) was assessed using the hydrodynamic photoamperometric method in the phosphate buffers. Ultimately, the optimum conditions of EG determination were studied in various pH values and applied bias potentials, and the pH = 3.0 and E= 1.0 V (vs. reference electrode) were determined as the optimum conditions. It was found that the photocurrent of EG was linearly dependent on the concentration of EG in the range of 3.0 × 10 ^?5 to 0.88 mol l ^?1 , and the detection limit of EG determination was found to be 7.2 × 10^?6 mol l^?1 (3 σ).     

Preparation and characterization of silver nanoparticles in natural polymers using laser ablation

In this paper we have done a comparative study on efficiency of natural polymers for stabilizing silver nanoparticles (Ag-NPs) prepared by laser ablation technique. The selected polymers are starch (St), gelatin (Gt) and chitosan (Ct). The fabrication process was carried out through ablation of a pure Ag plate by nanosecond Q-switched Nd?CYg pulsed laser (?? = 532?nm, 360?mJ/pulse). The stability of the samples was studied by measuring UV-visible absorption spectra of the samples one month after preparation. The result showed that the formation efficiency of NPs in St were highest and also the prepared NPs in St solution were more stable than other polymers during one month storage.     

Effect of process parameters on coating composition of cathodic-plasma-electrolysis-treated copper

Cathodic plasma electrolysis is a novel technique to form nanostructured layers on metallic surfaces by application of high voltage in a suitable aqueous electrolyte. In the present study, copper is treated by plasma electrolysis in 50 vol% ethanol electrolyte and coatings comprising carbon nanostructure and copper oxide are formed on the copper. The effect of some process parameters such as electrical conductivity, volume and temperature of electrolyte and ratio of anode to cathode surface area on current–voltage behaviour and subsequently coating compositions are investigated at 150 V deposition voltage. The composition and morphology of these coatings are characterized by X-ray diffraction, Raman spectroscopy and scanning electron microscopy. Different current–voltage behaviours, temperatures of substrate and the contents and energies of radicals and ions around the substrate by changes in the mentioned parameters cause different compositions from 100 vol% copper oxide to different ratios of copper oxide to carbon, the structure changing from amorphous to graphitic structure in carbon and amorphous to cubic morphology in copper oxide on the substrate. Therefore, the understanding of cathodic plasma electrolysis can be developed.     

模糊环境下汽车故障模式风险水平综合评价方法

针对车辆故障模式风险评价,提出了一种新的模糊综合评价方法,即先利用基于维修数据的失效模式与效果分析(FMEA)筛选出关键故障模式进行进一步研究,再分别采用模糊层次分析法(AHP)与模糊扩展全乘比例多目标优化(MULTIMOORA)计算风险评价因素与故障模式的权重,通过计算车辆故障模式的最终权重得到故障模式进行风险排序.同时利用逻辑语言表征评审专家的评估信息并将其转化为三角模糊数,实现了客观维修数据与专家经验判断的有机结合.利用本文提出的新评价方法对现代一款轻型客车进行故障模式风险评估与排序,进行灵敏度分析验证此方法的有效性.     

CONTAMINATION OF PATULIN IN CLEAR APPLE JUICE IN MASHHAD, IRAN

Patulin is a frequent contaminant of moldy and rotten apples and apple products. The aim of this study was to evaluate patulin contamination in 58 apple juices collected from a retail market in Mashhad during winter and spring of 2006.
Samples were assayed for patulin by high-performance liquid chromatography. Fifty-four samples were positive for patulin at levels that ranged from 10.5 to 121.8 µg/L, and six samples had patulin levels higher than 50 µg/L. The overall mean of patulin concentration was 29.2  ±  19.5 µg/L. Forty-eight samples had patulin concentration between 5 and 50 µg/L. Although the mean concentration of patulin samples was lower than Iranian maximum tolerated level of 50 µg/L, contamination of 10% of the samples at levels higher than 50 µg/L indicated the need for improving production techniques by the industry.

PRACTICAL APPLICATIONS

Studies have shown that the concentration of patulin may exceed the determined limits in apple juice and in other fruit products. Its presence can be a potential threat to the health of consumers, particularly children. The results may help us in understanding what should be the level of patulin in apple juice. The awareness of the apple industry of patulin contamination in fruit and the implementation of improved techniques for the production of apple products with reduced patulin concentrations have contributed to the quality of apple juice that are available on the Iranian market.