Thermodynamic and kinetic parameters have been determined suitable for the numerical simulation of the curing reaction of the epoxy/anhydride based casting resin system Araldite CY 225/HY 225/filler. In particular, the decisive role of the heating rate on the evaluation of the kinetic parameters from dynamic DSC-experiments is discussed.
Instrumental neutron activation analysis (INAA) was used for the determination of 23 elements and prompt gamma neutron activation analysis (PGNAA) was used for the determination of 10 elements in U.S. National Bureau of Standards (NBS) 1633A Fly Ash Standard Reference Material (SRM). The results are in excellent agreement with the limited number of NBS certified values available.
A preliminary study to evaluate the use of neutron activation analysis for the characterization of six groups of man-made
fibers for forensic purposes has been made. A total of 81 samples of acetate, acrylic, modacrylic, nylon, polyester and rayon
were analyzed. Small samples, approximately the size typically found during a crime scene search, were analyzed using a Ge(Li)
detector system following a 20 min irradiation at a flux of 5·1013 n·cm−2·sec−1. The following elements were determined quantitatively in one or more of the samples: Ti, Sr, Au, Zn, Sb, Br. Mn, Mg, Cu,
In, Co, Cu, V, K, Al, Cl, Na, Ca, and S. Significant qualitative and quantitative differences were found both between and
within the six groups. However, within certain groups some fibers from different manufacturers showed marked similarities
in qualitative and quantitative composition.
Thick target particle-induced X-ray emission (TTPIXE) spectrometry has been increasingly used for multielement and trace element analyses. The theoretical background and a formalism are presented for their evaluation by means of a minicomputer. Numerical results are given and compared with the experimental ones. The advantage of the program is shown by a special experimental example.
Authors:J. Vogt, C. Graham, M. Glascock, and R. Cobean
An extensive study of Mesoamerican obsidian source samples from 37 sites has been begun to better differentiate and define
the trace element content at known Mesoamerican obsidian quarries, with particular emphasis on those in Mexico. This paper
reports on the first results in that study as well as studies of sample contamination by grinding and results for the new
National Bureau of Standards No. 278 Obsidian SRM.
Authors:Kerstin Stingl, M.-T. Knüver, P. Vogt, C. Buhler, N.-J. Krüger, K. Alt, B.-A. Tenhagen, M. Hartung, A. Schroeter, L. Ellerbroek, B. Appel, and A. Käsbohrer
Campylobacter is a poorly recognized foodborne pathogen, leading the statistics of bacterially caused human diarrhoea in Europe during the last years.
In this review, we present qualitative and quantitative German data obtained in the framework of specific monitoring programs and from routine surveillance. These also comprise recent data on antimicrobial resistances of food isolates. Due to the considerable reduction of in vitro growth capabilities of stressed bacteria, there is a clear discrepancy between the detection limit of Campylobacter by cultivation and its infection potential. Moreover, antimicrobial resistances of Campylobacter isolates established during fattening of livestock are alarming, since they constitute an additional threat to human health.
The European Food Safety Authority (EFSA) discusses the establishment of a quantitative limit for Campylobacter contamination of broiler carcasses in order to achieve an appropriate level of protection for consumers. Currently, a considerable amount of German broiler carcasses would not comply with this future criterion. We recommend Campylobacter reduction strategies to be focussed on the prevention of fecal contamination during slaughter. Decontamination is only a sparse option, since the reduction efficiency is low and its success depends on the initial contamination concentration.