Characterisation of volatile components of Pinotage wines using comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC × GC–TOFMS)

As part of the ongoing research into the chemical composition of the uniquely South African wine cultivar Pinotage, the volatile composition of nine young wines of this cultivar was investigated using comprehensive two-dimensional gas chromatography (GC × GC) in combination with time-of-flight mass spectrometry (TOFMS). Headspace solid phase micro-extraction (HS-SPME) using a carboxen/polydimethylsiloxane (CAR/PDMS) fibre was used to extract the volatile compounds from the wine matrix. Extracts were analysed using an in-house developed GC × GC system equipped with a single jet, liquid nitrogen-based cryogenic modulator. In the current study, 206 compounds previously reported in wine and related matrices have been detected in nine Pinotage wines. Positive identification for 48 compounds was performed using authentic standards, while tentative identification of 158 compounds was based on deconvoluted mass spectra and comparison of linear retention indices (LRI) with literature values. Identified compounds included esters, alcohols, aldehydes, ketones, acids, acetals, furans and lactones, sulphur compounds, nitrogen compounds, terpenes, hydrocarbons, volatile phenols and pyrans. Volatile compounds potentially capable of influencing wine aroma are highlighted. Many of the compounds were common to all 9 wines, although volatile components unique to specific samples were also observed. The results represent the most detailed characterisation of volatile constituents of this cultivar reported to date.     

Application of a New Functionalized Nanoporous Silica for Simultaneous Trace Separation and Determination of Cd(II), Cu(II), Ni(II), and Pb(II) in Food and Agricultural Products

A novel sorbent for simultaneous separation of cadmium, copper, nickel, and lead was prepared by functionalizing SBA-15 nanoporous silica with dithizone. A solid-phase extraction method using the above sorbent was developed to separate and preconcentrate trace amounts of cadmium, copper, nickel, and lead ions from food and agricultural products by flame atomic absorption spectrometry measurements. The optimum experimental conditions such as pH; flow rates; type, concentration, and volume of the eluent; breakthrough volume; and effect of coexisting ions on the separation and determination of these heavy metals were evaluated. The extraction efficiencies for the mentioned heavy metals were greater than 97 %, and the limits of detection were 0.09, 0.16, 0.21, and 0.45 μg?L^?1 for cadmium, copper, nickel, and lead, respectively. The preconcentration factor for simultaneous analysis of the four heavy metals was found to be 100 approximately. The relative standard deviations of the method were <5 % for 10 separate column experiments for the determination of 5.0 μg of cadmium, copper, nickel, and lead ions. The adsorption capacity of the dithizone-SBA-15 was 189 mg?g^?1 for cadmium, 102 mg?g^?1 for copper, 91 mg?g^?1 for nickel, and 208 mg?g^?1 for lead.     

Design and simulation of a novel bipolar plate based on lung‐shaped bio‐inspired flow pattern for PEM fuel cell

Finding the optimal flow pattern in bipolar plates of a proton exchange membrane is a crucial step for enhancing the performance of the device. This design plays a critical role in fluid mass transport through microporous layers, charge transfer through conductive media, management of the liquid water produced in microchannels, and microporous layers and heat management in fuel cells. This article investigates different types of common flow patterns in bipolar plates while considering a uniform pressure and velocity distribution as well as a uniform distribution of reactants through all the surfaces of the catalyst layer as the design criteria so that there would be a consistent electron production by the catalyst layer. Then, by identifying the important parameters in achieving the best performance of a fuel cell, a microfluidic flow pattern is inspired from the lungs in the human body, and an innovative bipolar plate is suggested, which was not proposed before. Afterwards, numerical simulations were carried out using computational fluid dynamics methods, and the mentioned bipolar plate called lung‐shaped bipolar plate was modeled. Simulations in this research showed that the lung‐shaped microfluidic flow pattern is an appropriate flow pattern to gain maximum power and energy density. In other words, the best polarization curve and power density curve are obtained by using the lung‐shaped bipolar plate in a proton exchange membrane fuel cell compared with previously suggested patterns. Copyright © 2017 John Wiley & Sons, Ltd.     

Comparison of cigarette and water pipe smoking among female university students in Egypt.

This study investigated behavioral and sociodemographic factors associated with tobacco use among female university students patronizing water pipe cafes in Cairo, Egypt. We interviewed two groups of female university student smokers (100 and 96 students from a public and a private university, respectively). The interviews took place in nine water pipe cafes near the two universities. A logistic regression model was developed to analyze the relationship between tobacco-related knowledge and beliefs and the choice between smoking water pipe or cigarettes. Among these smokers, 27% smoked cigarettes only, 37.8% smoked water pipe only, and 35.2% smoked both types of tobacco. Most of the water pipe smokers (74.1%) preferred this method because they believe it to be less harmful than smoking cigarettes. More than half of the subjects were encouraged to start smoking by other females (56.6%). Curiosity was a significant factor for initiation (OR = 2.8, 95% CI = 1.3-6.2, p<.01). We found no significant differences between water pipe and cigarette smokers regarding current age, age at initiation, quit attempts, knowledge about the hazards of smoking, wanting to be fashionable, or smoking with friends. About one in four (23.7%) attempted to quit, with health cited as a major reason. An urgent need exists for correction of the misperception among this study population that water pipe smoking is safe and less harmful than cigarette smoking.