Search

Your search keyword '"Wrzeciono A"' showing total 498 results
Start Over Author "Wrzeciono A"
498 results on '"Wrzeciono A"'

304. Azole. 44.

Author

Gzella, Andrzej, Wrzeciono, Urszula, and Pöppel, Wolfram

Abstract

The structure analyses of racemic 3‐chloro‐1‐(4‐morpholino‐5‐nitro­imidazol‐1‐yl)­propan‐2‐ol, C10H15ClN4O4, (II), and 3‐chloro‐1‐(5‐morpholino‐4‐nitro­imidazol‐1‐yl)­propan‐2‐ol, C10H15ClN4O4, (III), have been undertaken in order to determine the position of the morpholine residue in these two isomers. The morpholine residue in (II) is connected at the 4‐position, while in (III), it is connected at the 5‐position of the imidazole ring. The morpholine mean planes and nitro groups in the two compounds deviate from the imidazole planes to different extents. The nitro groups in (II) and (III) take part in the conjugation system of the imidazole rings. In consequence, the exocyclic C—N bonds are significantly shorter than the normal single Csp2—NO2bond and the nitro groups in (II) and (III) show an extraordinary stability on treatment with morpholine and piperidine [Gzella, Wrzeciono & Pöppel (1999). Acta Cryst. C55, 1562–1565]. In the crystal lattice, the mol­ecules of both compounds are linked by O—H⃛N and C—H⃛O intermolecular hydrogen bonds.

Published
2000
Full Text
View/download PDF

307. Visualization of nonlocality in coupled map lattices

Author

Maciej Janowicz, Joanna Kaleta, Arkadiusz Orłowski, Piotr Wrzeciono, and Andrzej Zembrzuski

Subjects
Computer Vision and Pattern Recognition, Computer Graphics and Computer-Aided Design, Software
Abstract

Numerical simulations of coupled map lattices with various degree of nonlocality have been performed. Quantitative characteristics of recently introduced for local coupling have been applied in the nonlocal case. It has been attempted to draw qualitative conclusions about nonlocality from the emerging pictures.

308. Acoustic carpets

Author

Maciej Janowicz, Joanna Kaleta, Piotr Wrzeciono, and Andrzej Zembrzuski

Subjects
Computer Vision and Pattern Recognition, Computer Graphics and Computer-Aided Design, Software
Abstract

Initial-boundary value problem for linear acoustics has been solved in two spatial dimensions. It has been assumed that the initial acoustic field consists of two Gaussian distributions. Dirichlet boundary conditions with zero acoustic pressure at the boundaries have been imposed. The solution has been obtained with the help of a split-operator technique which resulted in a cellular automaton with uncountably many internal states. To visualize the results, the Python library matplotlib has been employed. It has been shown that attractive graphical output results in both the transient and stationary regimes. The visualization effects are similar to, but different from, the well-known quantum-mechanical carpets.

309. Triterpenoide. XIV. † [2,3-d]Isoxazoltriterpenderivate

Author

U. Wrzeciono, L. Zaprutko, E. Linkowska, and Andrzej Gzella

Subjects
chemistry.chemical_classification, Stereochemistry, Cyclohexane conformation, General Medicine, Crystal structure, Ring (chemistry), Hydroxylamine Hydrochloride, General Biochemistry, Genetics and Molecular Biology, chemistry.chemical_compound, Polycyclic compound, Triterpene, chemistry, Molecule, Isoxazole
Abstract

The X-ray crystal structure analyses of two triterpene isoxazoles, namely olean-2,12-dieno[2,3-d]isoxazol-28-oic acid methyl ester {methyl isoxazolo[4,5-b]olean-2,12-dien-28-oate, C 32 H 47 NO 3 , (2a)} and 19β,28-epoxy-18α-olean-2-eno[2,3-d]isoxazole {19β,28-epoxy-isoxazolo[4,5-b]-18α-olean-2-ene, C 31 H 47 NO 2 , (4a)} are described. These compounds were obtained by treatment of 2-formyl- or 2-hydroxymethylene derivatives of 3-oxoolean-12-en-28-oic methyl ester, (la) and (1b), and 19β,28-epoxy-18Hα-oleanan-3-one, (3a) and (3b), with hydroxylamine hydrochloride according to the method described by Govardhan, Reddy, Ramaiah & Rao [J. Indian Chem. Soc. (1983), pp. 858-860] for the synthesis of ring-A-fused triterpene [3,2-c]isoxazoles. The structures of the obtained [2,3-d]isoxazoles, (2a) and (4a), were confirmed by the comparison of the bord lengths and bord angles found for the isoxazole rings of compounds (2a) and (4a) with the corresponding data given in the literature. The isoxazole rings in both compounds are planar. Ring A in (2a) and (4a) has a conformation between the half-chair and sofa form. Rings B. D and E in (2a), and B, C, D and E in (4a) have the chair conformation. Ring C in (2a) has a distorted sofa form. In (2a), the rings A/B, B/C and C/D are trans-fused and the rings DIE cis-fused. In (4a), the A/B, B/C, C/D and DIE ring junctions are trans. The axial 02 and C28 atoms in (4a) are β oriented and form, together with the C17. C18 and C19 atoms, the five-membered ring F, which has an envelope conformation.

Catalog

Books, media, physical & digital resources
See catalog results