Epidemiologie des EHEC O104:H4/HUS-Ausbruchs in Deutschland, Mai bis Juli 2011

From May to July 2011 the largest outbreak of infections with enterohemorrhagic Escherichia coli (EHEC) O104:H4 and hemolytic uremic syndrome (HUS) reported to date with more than 3,800 diseased persons and 53 deaths occurred mainly in Northern Germany. Infections predominantly affected adults. This contrasts EHEC gastroenteritis and HUS surveillance data of previous years when mainly children where affected. In relation to disease onset (symptoms of diarrhea) of reported cases, the outbreak began on 8 May 2011, peaked on 22 May, and then subsided. On 26 July 2011, the outbreak was declared to be over by the Robert Koch Institute (RKI), because at this point in time new cases that were obviously associated with the outbreak and had a disease onset after 4 July had not been reported in the three previous weeks. Epidemiological studies of the RKI in cooperation with local and state public health authorities and hospitals as well as investigations by food safety authorities identified contaminated sprouts from producer A in Lower Saxony and, more specifically, imported fenugreek seeds used for sprout cultivation as the most likely vehicle of infection. Close cooperation between health and food safety authorities during the outbreak investigation was essential for solving the outbreak within a short timeframe.     

Adsorption of the Inhalation Anesthetic Isoflurane from Dry and Humid Atmosphere

For environmental and occupational safety reasons, the inhalation anesthetic isoflurane must be removed from indoor air in hospitals. The present work investigated experimentally the coadsorption of isoflurane and water on four different commercial adsorbents: two activated carbons and two zeolites. Adsorption isotherms from dry and humid atmosphere are shown and discussed, i.e., mixture data are compared with those of the pure substances. For all four adsorbents the dominant parameter regarding structural properties is the pore size distribution. In the case of the zeolites, the surface chemistry, especially the aluminum content, plays a role, too.     

Order acceptance in food processing systems with random raw material requirements

This study considers a food production system that processes a single perishable raw material into several products having stochastic demands. In order to process an order, the amount of raw material delivery from storage needs to meet the raw material requirement of the order. However, the amount of raw material required to process an order is not exactly known beforehand as it becomes evident during processing. The problem is to determine the admission decisions for incoming orders so as to maximize the expected total revenue. It is demonstrated that the problem can be modeled as a single resource capacity control problem. The optimal policy is shown to be too complex for practical use. A heuristic approach is proposed which follows rather simple decision rules while providing good results. By means of a numerical study, the cases where it is critical to employ optimal policies are highlighted, the effectiveness of the heuristic approach is investigated, and the effects of the random resource requirements of orders are analyzed.     

Formation of cross-linked glucose oxidase aggregates in mesocellular foams

Enzyme immobilization into solid mesoporous inorganic supports is a promising strategy to enable their use in continuous-flow fixed-bed reactors. In this study, the formation of cross-linked enzyme aggregates (CLEAs) of glucose oxidase (GOx) in the pores of mesocellular foams (MCFs) was investigated. The enzymes can enter the ultra-large cavities connected through the smaller windows, where their agglomeration and cross-linking with glutardialdehyde (GA) will take place. After cross-linking, the diameter of the CLEAs is larger than the diameter of the pore entrance and, thus, the enzymes are trapped in the pores of the support. By varying the experimental parameters, the optimum conditions for the preparation of active and stable immobilized biocatalysts were determined with respect to the resulting activity and to the enzyme loading. It is found that the preparation is preferably performed at pH 5.0, with a time delay between GA and GOx addition of 2 h and a n _GA/n _GOx-ratio of more than 400.     

Effect of excess silicate on the structure formation and textural properties of MTS materials

The synthesis of micellar templated silica (MTS) materials has been conducted with different SiO₂/CTAB molar ratios for two different cetyltrimethylammoniumbromide (CTAB) concentrations of 0.02 and 0.07 M to examine the structure formation for cubic (SBA-1) as well as for hexagonal (SBA-3) surfactant arrangement in acidic reaction medium with increasing silicate excess. Reaction products were analyzed with X-ray diffraction, N₂ physisorption and TG-MS. It was found that an increase of the silicate concentration leads to the formation of additional silica gel in the resulting MTS material, which causes not only a decrease of specific surface area and pore volume, but also of the mesopore diameter. The latter effect is explained by a proposed embedding theory. Furthermore, with increasing silicate content in the synthesis mixture a phase transformation from hexagonal to cubic pore arrangement was found for the CTAB concentration of 0.07 M and the maximum SiO₂/CTAB molar ratio for ordered pore arrangement has been determined.     

Degradation studies of a commercial radiation-resistant polypropylene sterilized by gamma and electron beam technology before and after subsequent accelerated aging cycles

Irradiation is one of the most widely used technologies for sterilization of medical products. Unfortunately, some polymers in the medical field are susceptible to high-energy radiation. In the case of polypropylene, this leads to yellowing and embrittlement due to degradation mechanisms. This study compares the impact of gamma and eBeam sterilizations at a dose of 45 kGy on a commercially available, radiation-resistant polypropylene in combination with accelerated aging studies. Mechanical behavior as well as yellowing, accompanied by structural investigations like molar mass characterization and crystallinity analysis, have been investigated. It is shown that eBeam has less damaging effects compared with gamma irradiation. This is shown by an initial drop in elongation at break by 46% for gamma irradiated samples in contrast to 24% decrease using eBeam irradiation. Also, an initial drop in molar mass by 43% was found for gamma irradiated samples and by 27% for eBeam. Change in color was observed by an initial increase in the yellowness index of 42% at samples after gamma irradiation, respectively, of 22% for eBeam irradiated samples. Interestingly, molar mass remained constant during aging, whereas yellowing and Embrittlement further change. Additionally, empirical equations were found, which describe the experimental data. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48436.     

The effect of contact torques on porosity of cohesive powders

The porosity of uniaxially compacted cohesive powders depends on the applied stress (including gravity). The case, where these stresses are weak, is considered. The compaction results in a porosity which is a function of sliding, rolling and torsion friction. By contact dynamics simulations it is shown that the influences of contact torques (static rolling and torsion friction) on the porosity are significant and approximately additive. The relevance for nano-powder pressure sintering is discussed.