Über die Verwendung von Glyoxal-bis(tert.-butylnitron) als Spin-Trap

On the Use of Glyoxal Bis (t-Butyl Nitron) as a Spin Trap Nitroxides derived from glyoxal bis(t-butyl nitrone), GBBN , have been studied by e.s.r. spectroscopy. Well resolved e.s.r. spectra exhibiting extra hyperfine splitting by magnetic active nuclei in γ-position have been recorded for the spin adducts of alkyl, as well as ^.N₃ and ^.CH₂Cl radicals. Enhanced stability was found for the spin adducts of halogen atoms. However, a wider application of this spin trap is limited by the strong superposition of the e.s.r. signals of different radical spin adducts which is directly related to almost identical conformations of these nitroxides.     

A New Field-Compatible Methodology for the Collection and Analysis of Fungal Fragments

A field-compatible collection system was developed and tested for the collection and analysis of fungal fragments. The new collection system consists of two types of Sharp-Cut cyclone samplers (PM _2.5 and PM _1.0 ) and an after-filter. Fungal particles are collected into three size fractions: (1) spores ( > 2.5 μ m); (2) a fragment-spore mixture (1.0–2.5 μ m); and (3) submicrometer-sized fragments ( < 1.0 μ m). The system was laboratory-tested using polystyrene latex (PSL) particles and particulate matter aerosolized from sporulating Aspergillus versicolor and Stachybotrys chartarum cultures. In addition to the particle count measured with direct-reading instruments, the (1 → 3)- β -D-glucan content in each size fraction was determined with the Limulus Amebocyte Lysate (LAL) assay.

Experiments conducted with PSL particles showed that the 50% cut-off values of the two cyclone samplers under the test conditions were 2.25 μ m and 1.05 μ m, respectively. No particle bounce onto the after-filter was observed when the total particle number entering the collection system was kept below 1.6 × 10 ⁸ . The (1 → 3)- β -D-glucan assay of samples aerosolized from both fungal species suggested that surface area is an important factor for determining the (1 → 3)- β -D-glucan content in the entire size-range of particles.

In conclusion, the new methodology is a promising tool for separating and analyzing fungal fragment samples.     

Industrial thin-film deodorization of seed oils with SoftColumnTM technology

Development of thin-film deodorizers started in the 1970ies, and they have been in industrial use since the middle of the 1980ies. The latest type is the SoftColumn^TM, a deodorizer specially developed for mild, low cost processing of seed oils. This deodorizer consists of a structured packing section and a flexible holding section. Regenerative oil heating/cooling and final heating is carried out in external, sparged vacuum heat exchangers, and the design of the heat exchangers leads to superior heat recovery and savings in fuel consumption. This set-up provides major advantages with regard to oil quality, economy, and flexibility. The extremely effective stripping of free fatty acids (FFAs) leads to shorter overall holding times of the oil at elevated temperatures, and steam consumption is cut to a third of the amount required in conventional deodorizers. The product oil has not only low acidity, low colour, good taste and stability, but also low trans fatty acid (TFA) concentrations. By adjusting the stripping steam flow the plant can be optimized both for tocopherol retention or removal. Flexible holding times allow optimization of heat bleaching/TFA formation without compromising on capacity. In this paper product analysis data on tocopherol and trans fatty acids from thin-film deodorizers in industrial operation are shown.     

Intercomparison exercise of high pressure gas flow test facilities within GERG

Ten of the main European gas Companies decided to carry out the second intercomparison exercise of high pressure test facilities within GERG (Groupe Européen de Recherches Gazières). The survey has compared the performances of 8 high pressure gas flow laboratories in the period autumn 1998–autumn 1999.

The aim was to check to what extent results obtained at the various laboratories are comparable and to reveal possible ways of improving the performances. Tests have been carried out using three transfer standard packages of three different diameters. The considered performance parameters have been: (1) agreement of results between laboratories, (2) short term stability and (3) day to day reproducibility of the reference flow.

The following main conclusions have been drawn:

• The majority of the laboratories involved in the intercomparison produced very accurate results. Despite the involvement of five independent traceability chains, 92.5% of the test results are within a band of ±0.25%.

• For most facilities the short term fluctuations are of the order of ±0.1%. Individual facilities may perform even better.

• This exercise allowed us to confirm the good results of the previous campaign and to identify some items to improve future intercomparisons.

Sputtered ZnO seed layer enhances photovoltaic behavior in hybrid ZnO/P3HT solar cells

We investigated the characteristics of inverted solar cells comprising bulk-heterojunction active layers of ZnO nanowire arrays and poly(3-hexylthiophene), P3HT. By utilizing a sputtered ZnO seed layer, we are able to grow vertically oriented ZnO nanowire arrays homoepitaxially. Unlike the ZnO nanowires that are grown on sol–gel derived seed layers, our nanowires are more uniform in their dimensions and spatial distribution. This sputtered seed layer also acts as the hole-blocking layer when these nanowire arrays are incorporated in solar cells; hybrid solar cells comprising these nanowires and P3HT exhibit power conversion efficiencies of 1.6%. To date, this is the highest efficiency observed for ZnO nanowire arrays:P3HT hybrid solar cells.