Methanol diffusion in polyimides: A molecular description

In this contribution the diffusion of methanol in two commercial polyimides (6FDA-ODA and Ultem^® 1000) is investigated in detail by gravimetric analysis and in-situ, time-resolved FTIR spectroscopy. Two methods of spectral data analysis are employed, namely difference spectroscopy (DS) and least-squares curve fitting (LSCF). These approaches provided complementary information about the overall diffusivity, the interactions and the dynamics of the molecular species present in the investigated systems. Spectroscopic measurements on thin film samples (2–4 μm) allowed us to identify the interaction site(s) on the polymer backbone and to propose likely structures for the H-bonding molecular aggregates.     

Antioxidant and anti-inflammatory activity of red and white wine extracts

Two commercially available Greek wines were treated with two different extraction methods in order to obtain either the total lipid fraction or several fractions containing different classes of phenolic compounds.     

Unemployment by gender and gender catching‐up: Empirical evidence from the Italian regions*

We examine the dynamic behaviour of unemployment rates by gender and of the gender unemployment gap over the 1992–2009 period by Italian regions. The results from unit root tests with unknown structural breaks indicate that the gender unemployment gap has narrowed in most cases. However, the pace of catching‐up and the dynamic behaviour characterizing the individual unemployment series differ substantially from one region to another. We comment on our results in the light of the reforms applied in the Italian labour market over the last two decades.     

Blackbody radiation shifts in optical atomic clocks

A review of recent theoretical calculations of blackbody radiation (BBR) shifts in optical atomic clocks is presented. We summarize previous results for monovalent ions that were obtained by a relativistic all-order single-double method, where all single and double excitations of the Dirac- Fock wave function are included to all orders of perturbation theory. A recently developed method for accurate calculations of BBR shifts in divalent atoms is then presented. This approach combines the relativistic all-order method and the configuration interaction method, which provides for accurate treatment of correlation corrections in atoms with two valence electrons. Calculations of the BBR shifts in B+, Al+, and In+ have enabled us to reduce the present fractional uncertainties in the frequencies of their clock transitions as measured at room temperature: to 4 × 10-19 for Al+ and 10-18 for B+ and In+. These uncertainties approach recent estimates of the limits of precision of currently proposed optical atomic clocks. We discuss directions of future theoretical developments for reducing clock uncertainties resulting from blackbody radiation shifts.     

Advantages and drawbacks of immunoaffinity columns in analysis of mycotoxins in food

A number of countries are setting legislations on mycotoxins. In order to reduce dispute between importing and exporting countries, the analytical data should be as comparable as possible, especially when levels are close to the regulatory limits. The present trend in the analysis of mycotoxins is to use immunoaffinity column (IAC) as a clean-up and enrichment technique, and Association of Official Analytical Chemists and European Union have validated methods which address a few food commodities. This study describes our experience using both conventional and IAC approaches in the analysis of three mycotoxins. Aflatoxins (AFs): Aflatoxin G1 has been detected by liquid-liquid partitioning methods with HPLC detection as false-positive in some maize. On IACs, this compound behaves as an AF, lowering the amount of the AFs trapped. The problem was solved using either TLC or HPLC with detection in the Kobra cell. Depending on the additives to food during the processing and cooking, the AFs might appear as an opened ring not recognised by the antibody. Fumonisins (FB): Compounds interfering with the FB's antibodies were also observed while analysing breakfast cereals leading to underestimation of FB. Ochratoxin A (OTA): Depending on the food composition and extraction techniques, OTA is underestimated with IAC in some breakfast cereals and coffee. These data strengthen the necessity to validate methods using IAC for each complex matrix.     

Evaluating benefits of low-cost household digesters for rural Andean communities

Low-cost household digesters are a promising appropriate technology which can help reducing the pressure on the environment due to deforestation and greenhouse gases emissions. The biogas and biofertilizer produced can alleviate poverty, by improving health conditions, increasing crops productivity and saving working time and burden for women and children. The aim of this study is to evaluate low-cost digesters technical, environmental and socio-economic impacts in rural communities of the Peruvian Andes, where a pilot project was developed during the last 3 years. Although the benefits are restricted by the performance of anaerobic digestion at high altitude, the results show that the digesters improve household living conditions and economy, while reducing environmental impacts. Biogas production covers around 60% of fuel needs for cooking, leading to 50-60% decrease in firewood consumption (i.e. deforestation) and greenhouse gases emissions; the annual income is increased by 3-5.5% due to fertilizer savings and potato sales. These values could be improved by enhancing digesters performance and the sustainability of the technology.     

Plasticizer migration from cross‐linked flexible PVC: Effects on tribology and hardness

Uses of flexible poly(vinyl chloride) (PVC) are restricted by plasticizer migration affecting material properties. Moreover, the use of phthalate‐based plasticizers is being questioned worldwide because of their potential toxicity to humans and environment. Chemical modification of PVC structure is one of the most effective tools for reduction of plasticizer diffusion. In this work, a flexible dry blend based on cross‐linked PVC was obtained using a difunctional amine, namely isophoron diamine (IPDA) as the cross‐linking agent. The gel fraction was evaluated from insoluble portions obtained by means of solvent extraction; the efficiency of cross‐linking in reducing the plasticizer leaching was evaluated by migration tests. Effects of addition of IPDA on PVC thermal stability were determined by thermogravimetric analysis (TGA). The cross‐linking reaction turned out to be responsible for accelerating thermal degradation. Tribological properties of flexible uncross‐linked, cross‐linked and rigid PVC were determined. Flexible formulations were held in contact for 32 days with rigid PVC sheets. Plasticizer migration towards the interface caused an increase of dynamic friction compared to that of the reference rigid PVC.Vickers microhardness h_Vickers values of rigid PVC sheets decreased due to plasticizer surface absorption. POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers     

Mathematical generation of normal data for evaluating myocardial perfusion studies

In this paper, we present a new mathematical method that synthesizes normal data sets for quantification of regional myocardium perfusion. In clinical practice, regional myocardial perfusion is often measured with a gamma camera and quantified via circumferential profile analysis. Normal reference profile data is used to increase the accuracy of the clinical interpretations. Our goal is to create reference data from an existing set of archived studies. An iterative mathematical method, based on two statistical hypotheses, was used to generate the study set instead of collecting normal examinations from a healthy population. Clinical validation is based on interpretations by six independent observers. Results of evaluation with synthesized normal data and its validation are presented.