A geometric model for active contours in image processing

Summary We propose a new model for active contours based on a geometric partial differential equation. Our model is intrinsec, stable (satisfies the maximum principle) and permits a rigorous mathematical analysis. It enables us to extract smooth shapes (we cannot retrieve angles) and it can be adapted to find several contours simultaneously. Moreover, as a consequence of the stability, we can design robust algorithms which can be engineed with no parameters in applications. Numerical experiments are presented.     

Optical studies of carbon nanotubes and nanographites

Resonance Raman and photoluminescence excitation (PLE) spectroscopies are used to study the optical properties of different types of carbon nanostructures such as carbon nanotube, nanoribbons, nanographites and graphite edges. In the resonance Raman experiments of carbon nanotubes, the (n,m) assignment is obtained by comparing the experimental and theoretical diameter and chirality dependence of the optical transitions. The influence of the environment on the optical transitions of the nanotubes is also obtained in the Raman experiments. The PLE measurements in different samples of carbon nanotubes show both direct and phonon-assisted optical transitions, and the results give new evidences that the optical transitions in nanotubes have an excitonic character, which is very strong for the low energy transitions. We also analyze the Raman spectra of nanoribbons and nanographites, showing that this technique is an important tool for defect characterization in graphitic materials, and can be used to distinguish the atomic structure of the graphite edges.     

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Infrared-active vibrational modes of single-walled carbon nanotubes

The IR-active vibrational modes of single-walled carbon nanotubes have been observed by optical transmission through thin films of bundled nanotubes. Because IR-active chemical functional groups, e.g., -COOH, -OH, might be attached to the tube walls and contribute additional spectral features, we have also studied the effects of chemical purification and long-term high-temperature vacuum annealing on the IR spectrum. Through comparison with theory, we are able to assign much of the sharp structure observed in our IR spectra.     

Pr?parative Trennung von biologisch aktiven Ribonucleins?uren durch HPLC

Ohne Zusammenfassung

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Preparative separation of biologically active ribonucleic acids by HPLC

     

Multiplication in changing bases: A note on Lewis Carroll

In this note, we examine a Carrollian treatment of the base of a number system as it appears in Alice in Wonderland.     

PHOTOSENSITIZED HERBICIDAL ACTION

Abstract— The herbicidal action produced by the colorless hydrocarbon fluoranthene sprayed on the leaves of growing plants does not occur when UV radiation is removed from the light to which the plants are exposed. If the UV component of the light under which the plants are grown is augmented, the herbicidal effect of fluoranthene is increased. The mechanism of this photodynamic action is discussed.     

Synthesis of mono-amino-functionalised ferrocene, ferrocene salts and ferrocenium salts

A number of mono-amino-functionalised ferrocenes, ferrocene salts and a mono-amino-functionalised ferrocenium salt have been synthesised and characterised. This represents a novel method of accessing these important classes of molecules. In the cases of some of the ferrocene salts, there are some interesting structural features in the solid state. These include N-H...O and N-H...F hydrogen bonds.