Measurement of temperature and emissivity of specularly reflecting glowing bodies

A new method of measuring the thermodynamic temperature of an object as well as the surface emissivity based on laser reflectivity has been developed. By using rotating analyzer ellipsometry, the light reflected from the sample at a specific angle of incidence can be analyzed for its ellipticity. The normal incidence reflectivity and emissivity were then extracted using standard relations. The thermodynamic temperature of the body was obtained simultaneously by measuring the intensity of emitted light at the same angle of incidence. Room temperature measurements were carried out on selected metals to test the system. Elevated temperature measurements on platinum foils showed that this technique was reliable and accurate for monitoring and measuring the temperature and emissivity of specularly reflecting glowing bodies. This paper is based on a presentation made in the symposium “Experimental Methods for Microgravity Materials Science Research” presented at the 1988 TMS-AIME Annual Meeting in Phoenix, Arizona, January 25-29, 1988, under the auspices of the ASM/MSD Thermo-dynamic Data Committee and the Material Processing Committee.     

Dispersions of functionalized single-walled carbon nanotubes in strong acids: solubility and rheology

The manipulation and processing of single-wall carbon nanotubes (SWNTs) is limited by their poor solubility in most common solvents. Covalent sidewall functionalization of SWNTs provides an excellent route to improve their solubility. Here we have studied the relationship between sidewall functionalization and phase behavior of solutions of functionalized SWNTs (f-SWNTs) in strong acids. We use centrifugation in conjunction with UV-Vis-nlR spectroscopy to quantify the solubility of f-SWNTs in strong acids. We image the dispersions of functionalized tubes by polarized light microscopy. We find that adding butyl groups increases marginally the solubility of SWNTs in 102% sulfuric acid in the isotropic phase; adding 9-nonadecyne groups roughly doubles the solubility of SWNTs. Viscosity measurements in dilute solutions are sensitive to de-bundling. We compare the viscosity-concentration dependence of dilute pristine and f-SWNTs to assess whether and how functionalization promotes de-bundling and stabilizes the tubes. The phase behavior and rheology of these f-SWNTs parallels with that of pristine SWNTs; 9-nonadecylated SWNTs have higher solubility and should be easier to process.     

Supramolecular porphyrin polymers in solution and at the solid-liquid interface

We have investigated in detail the self-assembly of a chiral porphyrin trimer in different solvents and correlated this behavior to the aggregation of the molecule at a solid-liquid interface. In n-hexane and cyclohexane, CD spectroscopy and dynamic and static light scattering studies showed that the porphyrin trimer self-assembles already at micromolar concentrations into long, chiral supramolecular polymers, which precipitate as fibers when the solution is drop-cast onto a mica surface. In contrast, in chloroform, the compound is molecularly dissolved up to concentrations of 0.2 mM and when micromolar solutions are drop-cast onto mica, no precipitation of large assemblies occurs. Instead, at the moment that the chloroform film becomes subject to spinodal dewetting and the porphyrin trimers within this film start to self-assemble, extended patterns of equidistant lines of single molecule thick columnar stacks are formed.     

Ausmaß und Folgen des Tabakkonsums und Passivrauchens in Deutschland

In consequence of the health hazards of smoking and environmental tobacco smoke (ETS) and the high prevalence in the German population there are more than 100,000 deaths annually in Germany. Still more than half of the German population ever starts smoking and currently about a third of the adult population and a fifth of the adolescents are smokers at present. Additionally about 55 percent of all non-smokers between the age of 18 and 79 are often exposed to ETS at home, at work or in their leisure time. A differentiation of smoking prevalence and of exposure to ETS concerning socio-economic determinants shows that social differences have grown with successive birth cohorts. Thus, significant social inequalities can be observed today. In contrast to this, gender differences are becoming increasingly irrelevant, particularly in smoking prevalence. Tobacco consumption and ETS therefore has become one high-priority field of action of health and prevention politics in Germany, which manifests in an improved tobacco control policy. International achievements in the implementation of a comprehensive tobacco control policy show however, that in Germany further efforts are needed to reduce smoking prevalence significantly. Eingegangen: 11. Mai 2007; Angenommen: 15. Mai 2007