Over the years nuclear methods have proved to be a valuable asset to industry in general and to the automotive industry in particular. This paper summarizes some of the most important recent contributions of nuclear technology to the development of vehicles having high quality and long-term durability. Radiotracer methods are used to measure engine oil consumption and the wear rates of inaccessible components. Radiographic and tomographic methods are used to image fluids and structures in engines and accessory components. Tracers are used to understand combustion chemistry and quantify fluid flow. Gauging methods are used for inspection and process control. Nuclear analytical methods are used routinely for materials characterization and problem solving. Although nuclear methods are usually considered as the means of last resort, they can often be applied more easily and quickly than conventional methods when those in industrial engineering and R&D are aware of their unique capabilities.
Cytolethal distending toxins (CDT) represent an emerging toxin family, widely distributed among pathogenic bacteria. The cdtABC genes in E. coli are either part of the genome of prophages, plasmid or pathogenicity island. In order to investigate the stability and the transfer potential of cdt-IV genes cdtB gene was replaced by chloramphenicol (Cm) resistance encoding cat gene in the avian pathogenic E. coli (APEC) strain E250. After consecutive passages in non-selective medium at 37 °C 7.6% (219/2900) of the investigated colonies of E250::cat strain became Cm-sensitive (CmS). To reveal deletion mechanism 177 CmS colonies were investigated for presence of cdtA, cdtC and cdtC associated gene by PCR. One hundred and sixteen colonies of the CmS colonies (65.5%) showed partial or complete deletion in the cdt-IV region. Progressive loss of the upstream genes of the cdt cluster in E250 compared to other CDT-IV producing APEC strains and the fact that all the potential deletion patterns were identified, suggests the presence of an unstable hitherto unknown genomic region. The failure of in vitro transfer of cdt genes into a porcine EPEC E. coli strain suggests that the deletion of cdt-IV flanking genes alone do not promote the spread of cdt-IV.
Authors:E. Urbanovici, H. A. Schneider, D. Brizzolara, and H. J. Cantow
A DSC study was carried out of the isothermal melt crystallization kinetics of poly(L-lactic acid), PLLA, at 110, 115, 120, 125 and 130‡C. The experimental data were evaluated within the framework of the well-known Avrami kinetic model and an extended model involving an additional third kinetic parameter . In order to perform the necessary numerical calculations, a number of functions built into the Mathematica® software system were used. The results showed that the isothermal melt crystallization kinetics of PLLA can be described adequately by both these kinetic models. It should also be stressed that the kinetic model of Urbanovici and Segal offers a better description of the experimental melt crystallization data of PLLA than the classical Avrami model.
Authors:E. Grell, E. Lewitzki, R. Schneider, G. Ilgenfritz, I. Grillo, and M. von Raumer
Differential scanning calorimetry (DSC) studies of micellar, 60 mM solutions of the octaethyleneglycol alkylethers C14E8 and C16E8 provide evidence for a narrow endothermic transition at 41 and 32C,respectively, characterized by an enthalpy change of
2 kJ mol−1 for both detergents. The observed thermal transition is indicative of a concerted transition of the surfactant molecules,
as illustrated on the basis of a simple molecular model. The effect of co-solvents such as different alcohols on the thermal
transition is investigated. Glycerol markedly lowers the transition temperature whereas the transition is absent in the presence
of at least 10% ethanol. The calorimetric transition correlates with the temperature dependent increase of viscosity and static
light scattering as well as with changes observed by small-angle neutron scattering (SANS). The SANS results provide clear
evidence for a distinct structural change occurring at the transition temperature, which is interpreted as a sphere-to-rod
transition of the detergent micelles. Moreover, the rod length increases with increasing temperature. We suggest that the
process causing the thermal transition acts as the prerequisite of the growth process.
Authors:S. Landsberger, A. Plionis, S. Biegalski, K. Foltz-Biegalski, E. Schneider, D. O’Kelly, J. Braisted, S. O’Kelly, and L. Welch
Over the last three years we have developed a very robust nuclear and radiochemistry program at The University of Texas at
Austin. The cornerstone of support was the DOE Radiochemistry Educational Award Program (REAP) that was awarded from 2002–2005.
A second award for the period of 2005–2008 was just received. This award has enabled us to support many educational activities
from vanguard classroom instruction, to laboratory enhancements, to research activities at the graduate and undergraduate
levels. Both traditional radiochemistry and advanced topics in nuclear instrumentation have been supported. Various DOE university
programs, national lab funding and IAEA fellowship grants, have allowed the Nuclear and Radiation Engineering Program at the
University of Texas to be at the forefront of nuclear and radiochemistry educational and research activities and help secure
the next generation of needed expertise.