Semi-implicit complementary volume scheme for solving level set like equations in image processing and curve evolution

Summary. We introduce linear semi-implicit complementary volume numerical scheme for solving level set like nonlinear degenerate diffusion equations arising in image processing and curve evolution problems. We study discretization of image selective smoothing equation of mean curvature flow type given by Alvarez, Lions and Morel ([3]). Solution of the level set equation of Osher and Sethian ([26], \[30]) is also included in the study. We prove and estimates for the proposed scheme and give existence of its (generalized) solution in every discrete time-scale step. Efficiency of the scheme is given by its linearity and stability. Preconditioned iterative solvers are used for computing arising linear systems. We present computational results related to image processing and plane curve evolution. Received April 25, 2000 / Revised version received June 11, 2001 / Published online November 15, 2001     

Improved high-performance liquid chromatographic method for the determination of coenzyme Q10 in plasma.

Coenzyme (Co) Q10 was dissociated from lipoproteins in plasma by treatment with methanol and extraction with n-hexane. Subsequent clean-up on silica gel and C18 solid-phase extraction cartridges with complete recovery (99 +/- 1.2%) produced a clean extract. High-performance liquid chromatographic (HPLC) separation was performed on a C18 reversed-phase column. Three simple, rapid procedures are presented: HPLC with final UV (275 nm) detection, a microanalysis utilizing a three-electrode electrochemical detector and a microanalysis with column-switching HPLC and electrochemical detection. The methods correlate very well with classical ethanol-n-hexane extraction with UV detection. The identity and purity of the Co Q10 peak were investigated and the resulting methods were concluded to be suitable for total plasma Co Q10 determination. The average level in healthy subjects was 0.80 +/- 0.20 mg/l; the minimum detectable Co Q10 plasma level was 0.05 and 0.005 mg/l for UV and electrochemical detection, respectively. The methods were applied to many samples and the plasma Co Q10 reference values for healthy subjects, athletes, hyperthyroid, hypothyroid and hypercholesterolaemic patients are given.     

Transition Metal Complexes with Bidentate Ligands Spanning trans-Positions. VIII. The reactions of the nucleophile trans-[RuCl(NO)(1)] (1 = 2,11-bis(diphenylphosphinomethyl)benzo[c]-phenanthrene) with carbon monoxide and the phosphite ligand (2) (2 = 1-ethyl-3,5,8-trioxa-4-phosphabicyclo (2.2.2)octane)

The preparation of the nucleophile trans-[RuCl(NO)( 1 )], where 1 is the bidentate ligand Ph₂PCH₂C₁₈CH₂PPh₂, and of the five-coordinate species [RuCl(CO)(NO)( 1 )], [RuCl(CO)(NO)(Ph₂PCH₂Ph)₂] and [RuCl(NO)( 2 )( 1 )] are reported. The crystal structure of [RuCl(CO)(NO)( 1 )] shows that the coordination around the metal atom is distorted trigonal bipyramidal with the phosphorus atoms in axial positions. The Ru? N? O bond angle is 142.8°. ¹H- and ³¹P-NMR. and \documentclass{article}\pagestyle{empty}\begin{document}$ \tilde \nu $\end{document}_NO IR.-data for the above complexes are reported and related to the coordination geometry.     

A weak formulation of boundary integral equations for time dependent parabolic problems

A weak formulation for ‘direct’ boundary methods for time dependent parabolic problems, deduced from distribution theory, is presented. The present approach seems particularly valuable when dealing with problems with non-integrable singularities and solutions with an exponential growth. Numerical examples are also reported for plane diffusion.     

Amphoteric 2-(sulfonylamino)benzaldehydes,secondary amines and isocyanides in the multicomponent synthesis of elusive N-alkyl-2,3-diaminoindoles

A novel interrupted Ugi reaction between ortho-sulfonylaminated aryl aldehydes, secondary amines, and isocyanides affords in good to high yields N-alkyl-2,3-diaminoindoles, providing access to a so far unexplored area of the indole chemical space. With only one single chemical operation, this novel reaction affords a broad gamma of substituted 2,3-diaminoindoles with five points of diversity. The success of this novel multicomponent transformation lies in presence of the amphoteric sulfonylamino group, which sequentially acts as a Brønsted acids and as a nucleophile the lack of need for additional catalysts and the high atom economy, with the loss of only one molecule of water, renders this approach a very effective one.     

Singular densities,test particles and generalized Hamiltonian systems in general relativity

We derive the motion equations and the structure equations of neutral and charged test particles, starting from the gravitational field equations. The method consists in the application of conservation laws to singular tensor densities, which represent regions of strong matter concentration. Moreover, a Hamiltonian formulation of the particle equations is given, in the form of implicit differential equations generated by Hamiltonian Morse families.     

Chemo-enzymatic approach to the synthesis of the antithrombotic clopidogrel

The (S)-2-chlorophenylglycine moiety is well recognized in the structure of (S)-clopidogrel, a known antithrombotic drug. We prepared an enantiomerically pure chiral building block via an enzyme-catalyzed resolution of (RS)-N-Boc-2-chlorophenylglycine methylester. The best results were obtained by means of an immobilized subtilisin, the cross-linked enzyme aggregate (Alcalase-CLEA®). The high enantiomeric excess of the synthon obtained remained the same over the course of clopidogrel synthesis; the simplicity of the process makes this pathway suitable for large-scale preparation.     

Highly photoresponsive monolayer-protected gold clusters by self-assembly of a cyclodextrin-azobenzene-derived supramolecular complex

Reversibly-photoswitchable gold nanoparticles containing azobenzene and exhibiting a light response "virtually identical" to that of the free chromophore were achieved by self-assembling a host-guest inclusion complex between alpha-cyclodextrin and an azobenzene-terminated alkanethiol in an aqueous medium.     

Stable isotope ratio analysis as a tool to discriminate between rainbow trout (O. mykiss) fed diets based on plant or fish-meal proteins

The use of stable isotope ratio analysis (SIRA) as a rapid analytical tool to characterize and discriminate farmed fish on the basis of the feedstuffs included in the diet formulation is discussed. Two isoproteic (44.8%) and isolipidic (19.6%) extruded diets were formulated: a fish-meal-based diet (FM diet), containing fish meal as the sole protein source; a plant-protein-based diet (PP diet), where pea protein concentrate and wheat gluten meal replaced 80% of fish meal protein. The diets were fed to eight groups of rainbow trout (initial body weight: 106.6g) for 103 days in two daily meals under controlled rearing conditions. Growth performance (final body weight: 318.5 g; specific growth rate: 1.06%) and feed-to-gain ratio (0.79) were not affected by the dietary treatment. The differences in isotopic values of the two diets were clearly reflected in the different carbon and nitrogen isotopic values in rainbow trout fillets. The delta(13)C and delta(15)N values of muscle of farmed rainbow trout showed differences between farmed fish fed a fish-protein-based diet (-20.47 +/- 0.34 and 12.38 +/- 0.57 for delta(13)C and delta(15)N, respectively) and those fed a plant-protein-based diet (-23.96 +/- 0.38 and 7.15 +/- 0.51 for delta(13)C and delta(15)N, respectively). The results suggest that SIRA provides a robust and verifiable analytical tool to discriminate between fish fed on a plant or a fish protein diet.