[Does external heat application have an influence on kidney function?].

Two challenges for effectively exploiting the remarkable properties of single-walled carbon nanotubes (SWNTs) are the isolation of intact individual nanotubes from the raw material and the assembly of these isolated SWNTs into useful structures. In this study, we present atomic force microscopy (AFM) evidence that we can isolate individual peptide-wrapped SWNTs, possibly connected end-to-end into long fibrillar structures, using an amphiphilic alpha-helical peptide, termed nano-1. Transmission electron microscopy (TEM) and well-resolved absorption spectral features further corroborate nano-1's ability to debundle SWNTs in aqueous solution. Peptide-assisted assembly of SWNT structures, specifically in the form of Y-, X-, and intraloop junctions, was observed in the AFM and TEM images.

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PubMed2004

Two enzymes in one; two yeast peroxiredoxins display oxidative stress-dependent switching from a peroxidase to a molecular chaperone function.

Although a great deal is known biochemically about peroxiredoxins (Prxs), little is known about their real physiological function. We show here that two cytosolic yeast Prxs, cPrxI and II, which display diversity in structure and apparent molecular weights (MW), can act alternatively as peroxidases and molecular chaperones. The peroxidase function predominates in the lower MW forms, whereas the chaperone function predominates in the higher MW complexes. Oxidative stress and heat shock exposure of yeasts causes the protein structures of cPrxI and II to shift from low MW species to high MW complexes. This triggers a peroxidase-to-chaperone functional switch. These in vivo changes are primarily guided by the active peroxidase site residue, Cys(47), which serves as an efficient "H(2)O(2)-sensor" in the cells. The chaperone function of these proteins enhances yeast resistance to heat shock.

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PubMed2004

Mid-infrared laser-induced superheating of water and its quantification by an optical temperature probe.

Free-running thulium laser pulses (Cr:Tm:YAG, lambda = 2.01 microm, tp = 300 micros) were applied to a purified, degassed water sample and the resulting temperature rise was investigated by an optical temperature probe. The probe detected water reflectance index changes with temperature and also the onset of vaporization, which was found to occur in a superheat regime, at approximately 230 degrees C. The experimental data were compared with theoretical temperature calculations, and deviations of less than 20 degrees C were stated. The best agreement between theory and experiment was found for temperatures below 180 degrees C, defining by this the method's high accuracy limit. In conclusion, both the optical temperature probe and the presented calculations can help to improve dosimetry in pulsed IR laser applications by precise temperature measurement and prediction.

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