Development of an in-house method for the incorporation of model migrants in polyethylene films and determination of diffusion constants in food

Two methods were tested and compared for the additivation of low density polyethylene (LDPE). The aim was to obtain highly contaminated plastic films to enable the study of migration (diffusion and partition phenomena). One of the methods involved immersion of low density polyethylene (LDPE) films in a concentrated solution of the selected substances. The other method involved achieving close contact of plastic films with a polyethylene wax contaminated with the selected compounds. The PE-wax method provided better results as regards the final concentration and homogeneity of the contaminants in the plastic films (deviations between replicates for each plastic film was lower than 10% for both migrants tested). This method was therefore considered suitable for preparing a homogeneous additive release system. Finally, to test the applicability of the method, concentration profiles were studied in chocolate spread placed in contact with the contaminated films, and diffusion coefficients were estimated in this foodstuff. Estimated diffusion coefficients were 4.6 × 10⁻⁰⁷ cm²/s for DPBD and 3.2 × 10⁻⁰⁷ cm²/s for triclosan in the same conditions.     

The Propensity of Wooden Crevices to Smoldering Ignition by Firebrands

Fire Technology - Fires occurring at the wildland-urban interface (WUI) have rapidly increased in frequency and severity over the past few decades. As a result of these extreme fires, multiple...     

Ignition and Burning of Fibreboard Exposed to Transient Irradiation

Fire Technology - Natural materials like wood are increasingly used in the construction industry, making the understanding of their ignition and burning behaviour in fires crucial. The state of the...     

基于有限元法的汽车变速器齿轮与轴承优化

采埃孚集团开发和生产了种类繁多的传动齿轮。对于齿轮的优化和可靠设计,有限元法是尤为适合的。而且,这种方法能容易集成于采埃孚的程序系统。本文展示了在开发过程中如何运用该方法进行齿轮优化。此外,文中多处演示了齿轮和轴承之间的相互作用。这也是采埃孚集团致力于开发轴承计算的原因。文中实例展现了如何优化滚动轴承以达到理想的齿轮接触印痕。当然,这些优化方法也适用于传动齿轮。     

ESBL-producing E. coli in Austrian sewage sludge

The aim of this study was to investigate the degree of contamination of sewage sludge with ESBL-producing Escherichia coli strains and the effectiveness of different sewage sludge treatment methods.Monthly sewage sludge samples were collected between January and September 2009 in 5 different sewage treatment plants and tested for the presence of ESBL E. coli. In addition, the number of colony forming units (CFU) of E. coli and coliform bacteria before and after the different sludge treatment methods (aerobic/anaerobic digestion, lime stabilization, and thermal treatment) was investigated.Of the 72 sewage sludge samples investigated, ESBL-positive E. coli were found in 44 (61.1%) sewage sludge samples. The classification of β-lactamase groups was carried out in 15 strains resulting in the detection of 2 different groups (CTX-M and TEM) of bla genes. All 15 of them had a CTX-M gene and 4 of these strains furthermore carried a TEM gene.With regard to the CFU of E. coli and coliform bacteria, thermal treatment and lime stabilization following dehydration sufficiently reduced pathogen concentrations. The plants using merely stabilization and dehydration showed an increase of E. coli and coliform bacteria and thus also an increase in ESBL-producing E. coli.     

Development of an HPLC method for measurements of the stability of Irganox-type polymer antioxidants in fatty food simulants

 A reversed-phase high-performance liquid chromatography (RP-HPLC) method has been developed to measure the stability of four Irganox-type polymer antioxidants (Irganox 245, Irganox 1035, Irganox 1098 and Irganox 3114) in an olive oil food simulant and isooctane, which has been proposed as an alternative fatty food simulant. The tests of stability in olive oil were carried out under three different conditions, i.e. 40°C for 10 days, 100°C for 1 h and 175°C for 1 h. The exposure conditions for isooctane were 60°C for 3 h. Results showed that for all additives tested no instability phenomena in olive oil or isooctane simulants were observed under the exposure conditions applied. The analytical methodology developed could eventually be used for stability testing and migration studies of other similarly structured antioxidants in fatty food simulants. Received: 11 September 1997     

Investigations on the oxalic acid content of honey from oxalic acid treated and untreated bee colonies

Varroa destructor, an ectoparasitic mite, is one of the major pests of honeybees in many parts of the world. In order to keep bee colonies alive and productive, effective biological, biotechnical, or acaricidal control measures are necessary. Oxalic acid is one substance under discussion to replace synthetic acaricides (e.g. pyrethroids, organophosphates) to minimize the risk of residues in bee products. The application of oxalic acid based solutions (Bienenwohl or a self-prepared oxalic acid solution with sugar) to control Varroa destructor resulted in no relevant changes in the oxalic acid content of honey produced the following year, compared with honey samples from untreated colonies from the same location. The range of oxalic acid content in honey was 5–68 mg/kg in oxalic acid treated and 5–65 mg/kg in untreated colonies. The oxalic acid content of the honey was positively correlated with its electrical conductivity and thus with its original nectar or honeydew source.