Search results for "Pyramid"
showing 10 items of 410 documents
Multiresolution Analysis for Irregular Meshes
2003
International audience; The concept of multiresolution analysis applied to irregular meshes has become more and more important. Previous contributions proposed a variety of methods using simplification and/or subdivision algorithms to build a mesh pyramid. In this paper, we propose a multiresolution analysis framework for irregular meshes with attributes. Our framework is based on simplification and subdivision algorithms to build a mesh pyramid. We introduce a surface relaxation operator that allows to build a non-uniform subdivision for a low computational cost. Furthermore, we generalize the relaxationoperator to attributes such as color, texture, temperature, etc. The attribute analysis…
Which social program supports sustainable grass-root finance? Machine-learning evidence
2019
Resources for development are used efficiently when social programs help to promote at the same time the sustainability of grass-root financial associations at the bottom of the pyramid. This study applies machine-learning to a worldwide database of grass-root associations in order to identify which social programs are good predictors of financial returns in the groups. The results indicate that education, income-generating activities and health programs are the most frequent programs provided by development agencies. Business training is not the most frequent intervention applied to grass-root associations, but it is in fact the most important social program to encourage financial sustaina…
Aromatic dicarboxylate incorporated new di- and tetranuclear cobalt(II) complexes: Synthetic and structural aspects, and evaluation of properties and…
2020
Abstract The synthetic and structural aspects as well as evaluation of magnetic properties and catalytic activity toward aerial oxidation of 3,5-di-tert-butylcatechol to 3,5-di-tert-butylbenzoquinone of three new, two di- and one tetranuclear cobalt(II) complexes, [Co2(cpdp)(Hphth)]∙5H2O (1), [Co2(cpdp)(Hisophth)] (2) and [Co4(cpdp)2(terephth)]∙4.5CH3OH·5.5H2O (3), based on a symmetrical multidentate ligand, N,N'-Bis[2-carboxybenzomethyl]-N,N'-Bis[2-pyridylmethyl]-1,3-diaminopropan-2-ol (H3cpdp) in combination with exogeneous aromatic dicarboxylic acids, such as phthalic acid (H2phth), isophthalic acid (H2isophth) and terephthalic acid (H2terephth) are reported. All three coordination compl…
The ionic tin(IV) complex tri-μ2-methoxy-μ3-oxo-tris[di-tert-butyltin(IV)] tri-μ2-methoxy-bis[tert-butyldimethoxystannate(IV)]
2004
The solid-state of the title compound, [Sn3(C4H9)6(CH3O)3O][Sn2(C4H9)2(CH3O)7], consists of distinct [tBu6Sn3(μ-OCH3)3(μ3-O)]+ cations and [tBu2Sn2(OCH3)4(μ-OCH3)3]− anions, apparently formed as a result of slow hydrolysis of pure di(tert-butyl)dimethoxystannane, tBu2Sn(OCH3)2. In the monocation, the coordination about the Sn atoms is distorted trigonal bipyramidal, and, in the monoanion, distorted octahedral. The trigonal bipyramidal arrangement induces planarity of the Sn3O4 motif.
Synthesis, characterization, crystal structures and magnetic exchange in dinuclear copper complexes with 3-amino-1-propanol as terminal and bridging …
1990
Abstract The synthesis, X-ray structures and spectroscopic and magnetic properties are described for two groups of dinuclear Cu(II) compounds with the ligand 3-amino-1-propanol (Hap). The formulae of the compounds are for group A: [Cu(ap)(anion)]2, in which ap is the dehydronated Hap and the anions are formate, nitrate, chloride and bromide and for group B: [Cu(ap)(Hap)]2(anion)2, with anion = iodide, bromide, chloride, nitrate and tetrafluoroborate. The structure of group A compounds consists of dinuclear units with the co-planar centrosymmetric chromophore ANCuOO′CuNA, in which the A ligands (anions) bridge to neighbouring units as axial ligands, thereby forming infinite chains. Dimer Cu……
Organotin(IV) azido and mixed azidothiocyanato complex anions; A Mössbauer and vibrational spectroscopic study
1975
Abstract Tetraphenylarsonium and tetramethylammonium salts of the complex anions Ph 3 Sn(N 3 ) − 2 , Ph 3 Sn(N 3 )(NCS) − , Me 2 Sn(N 3 ) 2− 4 and Ph 2 Sn(N 3 ) 2 (NCS) 2− 2 have been synthesized, and the solid state configuration of the complex anions has been studied by Mossbauer and vibrational spectroscopies. Trigonal bipyramidal structures are advanced for the Ph 3 Sn IV derivatives, with equatorial SnC 3 and apical pseudohalide ligands, while the R 2 Sn IV compounds are assumed to be trans -octahedral species. The NCS − ligands are observed to be N-bonded to Sn IV . Conductance and PMR (for the Me 2 Sn IV compound) data suggest the presence of the complex anions also in solution phase…
Soft Pyramid Symmetry Transforms
2005
Pyramid computation is a natural paradigm of computation in planning strategies and multi-resolution image analysis. This paper introduces a new paradigm that is based on the concept of soft-hierarchical operators implemented in a pyramid architecture to retrieve global versus local symmetries. The concept of symmetry is mathematically well defined in geometry whenever patterns are crisp images (two levels). Necessity for a soft approach occurs whenever images are multi-levels and the separation between object and background is subjective or not well defined. The paper describes a new pyramid operator to detect symmetries and shows some experiments supporting the approach. This work has bee…
Structural basis and effect of copper(II) complexes with 4-oxo-thiazolidine ligands on DNA binding and nuclease activity
2020
Abstract Seven novel Copper(II) complexes, namely [Cu(Am4DHotaz)(H2O)2](ClO4) (1), [Cu(Am4DHotaz)(NO3)(MeOH)]·H2O (2), [Cu(Am4Motaz)2(H2O)](ClO4)2·0.83H2O (3), [Cu(Am4Motaz)2(NO3)]NO3·MeOH (4), [Cu(Am4Eotaz)2(NO3)]3(NO3)3·2H2O (5), [Cu(Am4Eotaz)2(ClO4)](ClO4) (6) and [Cu(Am4Eotaz)(ClO4)(H2O)](ClO4) (6a) (HAm4DHotaz = N′-(4-oxothiazolidin-2-ylidene)pyridine-2-carbohydrazonamide, Am4Motaz = N′-(3-methyl-4-oxothiazolidin-2-ylidene)pyridine-2-carbohydrazonamide and Am4Eotaz = N′-(3-ethyl-4-oxothiazolidin-2-ylidene)pyridine-2-carbohydrazonamide), have been successfully synthesized and characterized by several physicochemical techniques and, for 1–6 complexes, single crystal X-ray diffraction. Ha…
Syntheses, crystal structures and magnetic properties of copper(II) polynuclear and dinuclear compounds with 2,3-bis(2-pyridyl)pyrazine (dpp) and pse…
2001
Abstract The preparation, crystal structures and magnetic properties of four heteroleptic copper(II) complexes with 2,3-bis(2-pyridyl)pyrazine (dpp) and azide, cyanate or thiocyanate as ligands are reported, [Cu(dpp)(N3)2]n (1), [Cu(dpp)(NCO)2]n (2), [Cu(dpp)(NCS)2]2 (3) and [Cu(H2O)(dpp)(NCS)2]2·2H2O (4). Compounds 1 and 2 are isomorphous, triclinic, space group P1, and consist of mononuclear building blocks featuring copper atoms with close to square planar coordination geometries. The mononuclear units are, however, associated into chains through weak axial Cu–N bonds formed by end-on asymmetrically bridging azido/cyanato groups and by pyridyl nitrogen atoms. Taking these contacts into a…
Coordinative Versatility of Guanazole [3,5‐Diamino‐1,2,4‐triazole]: Synthesis, Crystal Structure, EPR, and Magnetic Properties of a Dinuclear and a L…
2006
New complexes with guanazole (3,5-diamino-1,2,4-triazole = Hdatrz), [Cu 2 (Hdatrz) 2 (μ-OH 2 )(H 2 O) 4 (SO 4 )](SO 4 )·3.5H 2 O (1) and [Cu 3 (Hdatrz) 4 (μ-Cl) 2 (H 2 O) 4 (SO 4 ) 2 ]·11.4H 2 O (2), have been prepared and structurally characterized. Complex 1 is a noncentrosymmetric dinuclear compound in which the cop-per(II) ions are bridged by two triazole ligands and one μ-OH 2 molecule, with a Cu(1)···Cu(2) distance of 3.4945(8) A. The chromophores are Cu(1)N 2 O 2 O' (square pyramidal), and Cu(2)N 2 O 2 O'O" (octahedral). Complex 2 has a linear trinuclear copper(II) structure, with two crystallographically independent copper(II) atoms. Neighboring copper(II) ions are linked by two tri…