Evaluation of the Surface Roughness of Cystine Stones Using a Visible Laser Diode Scattering Approach

To understand the processes of fragmentation and the chemical reactivity of solids, proper characterization of surface topography is crucial. This paper describes a non-destructive technique of quantifying the surface roughness of cystine renal stones, using visible laser diode scattering and fractal geometry. Fragments of cystine stones were mounted on microscope slides and coated by a carbon-sputtering apparatus. The slides were placed under a dynamic active-vision system, using a visible laser diode to measure three-dimensional surface coordinates. The data obtained were analyzed by fractal geometry. Surface fractal dimensions were determined by the variation method. The results showed that the surface of a compact-size sample can be evaluated quantitatively. The technique is valuable for the accurate presentation of surfaces in three dimensions

First stages of low temperature and low pressure carbonization of Si(001) in acetylene"

The thermal growth of 3C-SiC films at 820 degrees C in acetylene (chosen among other hydrocarbons because of its high reactivity with Si) was performed and the resulting films were analyzed by nuclear reaction analysis (NRA), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM), Films were grown on clean single domain 2 x 1 reconstructed Si (0 0 1)vicinal surfaces either in natural (C2H2) or in 99% deuterium enriched (C2D2) acetylene under 2 x 10(-6) Torr, In order to characterize the electronic structure and the short range order of the films, XPS and its by-product X-ray photodiffraction (XPD) were performed in situ in an analysis chamber connected to the preparation chamber, The growth kinetics was followed by measuring, ex situ, the amount of incorporated carbon using the C-12(d,p)C-13 reaction at 970 keV, while for determining the hydrogen incorporation in the films the D(He-3,p)He-4 reaction at 700 keV was used. Also ex situ, the film morphology was followed by SEM as the thickness of the layer increased. By using these complementary techniques, phenomena like I-I incorporation, C in-diffusion and 3C-SiC nucleation have been evidenced at the very beginning of the growth (amount of C-12 incorporated in the films smaller than 10(16) atoms/cm(2)). Besides, it was observed that the imperfect coalescence of 3C-SiC nuclei determine the morphology of films grown during longer times