Search results for "Pyramid"
showing 10 items of 410 documents
Mediterranean diet and longevity: an example of nutraceuticals?
2013
The Mediterranean diet (Mediet) is an eating pattern characterizing a lifestyle and culture that has been reported to contribute to better health and quality of life. The Mediet reflects food patterns typical of Mediterranean regions, where olive oil plays an essential role in the food pyramid. Olive oil is located in the middle and it is considered the principal source of dietary fat because of its high nutritional quality (particularly extra virgin olive oil). Several studies have shown the effect of the Mediet on healthy status by lowering the rates of coronary heart disease, certain cancers, and some other age-related chronic diseases. Although the scientific literature regarding diet a…
Synthesis, characterization, crystal structures and in vitro antistaphylococcal activity of organotin(IV) derivatives with 5,7-disubstituted-1,2,4-tr…
2011
Abstract New organotin(IV) complexes of 5,7-ditertbutyl-1,2,4-triazolo[1,5-a]pyrimidine ( dbtp ) and 5,7-diphenyl-1,2,4-triazolo[1,5-a]pyrimidine ( dptp ) with 1:1 and/or 1:2 stoichiometry were synthesized and investigated by X-ray diffraction, FT-IR and 119 Sn Mossbauer in the solid state and by 1 H and 13 C NMR spectroscopy, in solution. Moreover, the crystal and molecular structures of Et 2 SnCl 2 (dbtp) 2 and Ph 2 SnCl 2 (EtOH) 2 (dptp) 2 are reported. The complexes contain hexacoordinated tin atoms: in Et 2 SnCl 2 (dbtp) 2 two 5,7-ditertbutyl-1,2,4-triazolo[1,5-a]pyrimidine molecules coordinate classically the tin atom through N(3) atom and the coordination around the tin atom shows a …
Substituted 1,4-Diaza-1,3-butadiene Monocyclopentadienyl Titanium Complexes. Crystal Structure of Ti(η5-C5Me5)(η4-iPrNCHCHNiPr)Me
2000
We report the synthesis of 1,4-diaza-1,3-butadiene (dad) complexes Ti(η5-C5R5)(η4-R‘2-dad)Cl (R = H, Me; R‘ = iPr, tBu) by reaction of Ti(η5-C5R5)Cl3 (R = H, Me) with the dilithium salts of diisopropyl- and di-tert-butyl-substituted 1,4-diaza-1,3-butadienes (Li2[R‘2-dad]). Alkylation of the pentamethylcyclopentadienyl diisopropyl and di-tert-butyl derivatives with methylmagnesium chloride and methyllithium gave complexes Ti(η5-C5Me5)(η4-iPr2-dad)Me and Ti(η5-C5Me5)(η4-tBu2-dad)Me, respectively. Addition of excess water to di-tert-butyl chloro complexes gave the oxo-bridged complexes [{Ti(η5-C5R5)(η4-tBu2-dad)}2(μ-O)] (R = H, Me). The temperature-dependent spectroscopic behavior of Ti(η5-C5H…
Moderno BI un analītisko platformu īpašību izpēte
2018
Bakalaura darbs apskata moderno BI un analītisko platformu īpašības, ko piedāvā dažādi autori. Padziļināti tiek apskatīts Gartner uzņēmuma piedāvātais BI un analītisko platformu Maģiskais kvadrants, kas ar vairāku kritēriju palīdzību, iedala uzņēmumus 4 kategorijās: Līderi, Nišas spēlētāji, Redzētāji un Pretendētāji. Darbā tika analizēti 3 kritēriji, kas tika apskatīti ar katra kvadranta rīka palīdzību - MicroStrategy, Tableau, Sisense un Pyramid Analytics. Darba mērķis ir noskaidrot, kādas īpašības raksturo jaunākos BI rīkus un izvērtēt MicroStrategy, Tableau, Sisense un Pyramid Analytics rīku atbilstību moderno BI rīku klasei (cik lielā mērā atbilst/neatbilst) - gan pēc dokumentācijas, ga…
Spatiotemporal receptive fields: A dynamical model derived from cortical architectonics
1986
We assume that the mammalian neocortex is built up out of some six layers which differ in their morphology and their external connections. Intrinsic connectivity is largely excitatory, leading to a considerable amount of positive feedback. The majority of cortical neurons can be divided into two main classes: the pyramidal cells, which are said to be excitatory, and local cells (most notably the non-spiny stellate cells), which are said to be inhibitory. The form of the dendritic and axonal arborizations of both groups is discussed in detail. This results in a simplified model of the cortex as a stack of six layers with mutual connections determined by the principles of fibre anatomy. This …
Phosphatase-like Activity of Tetranuclear Iron(III) and Zinc(II) Complexes
2018
Three new tetranuclear iron(III) and zinc(II) complexes, [Fe4(cpdp)2(phth)2(OH)2]·8H2O (1), [Fe4(cpdp)2(terephth)2(OH)2] (2), and [Zn4(Hcpdp)2(suc)]Br2·12H2O (3), have been synthesized as models for the active site of phosphoester hydrolases by utilizing a polydentate ligand, N, N'-bis[2-carboxybenzomethyl]- N, N'-bis[2-pyridylmethyl]-1,3-diaminopropan-2-ol (H3cpdp) in combination with exogeneous phthalate (phth), terephthalate (terephth), and succinate (suc). Single crystal X-ray analyses reveal that the metallic core of complex 1 consists of four distorted octahedral iron(III) ions with average intraligand Fe---Fe separation of 3.656(2) A, while the structure 3 represents a tetranuclear m…
Guanine-containing copper(ii) complexes: synthesis, X-ray structures and magnetic properties
2008
Three new compounds of formula {[Cu(gua)(H(2)O)(3)](BF(4))(SiF(6))(1/2)}(n) (1), {[Cu(gua)(H(2)O)(3)](CF(3)SO(3))(2).H(2)O}(n) (2) and [Cu(gua)(2)(H(2)O)(HCOO)]ClO(4).H(2)O.1/2HCOOH] (3) [gua = 2-amino-1H-purin-6(9H)-one] showing the unprecedented coordination of neutral guanine, have been synthesised and structurally characterized. The structures of the compounds 1 and 2 contain uniform copper(II) chains of formula [Cu(gua)(H(2)O)(3)](n)(2n+), where the copper atoms are bridged by guanine ligands coordinated via N(3) and N(7). The electroneutrality is achieved by uncoordinated tetrafluoroborate and hexafluorosilicate (1) and triflate (2). Each copper atom in 1 and 2 is five-coordinated in …
Geometric Isomerism in Pentacoordinate Cu2+ Complexes: Equilibrium, Kinetic, and Density Functional Theory Studies Reveal the Existence of Equilibriu…
2009
A ligand (L1) (bis(aminoethyl)[2-(4-quinolylmethyl)aminoethyl]amine) containing a 4-quinolylmethyl group attached to one of the terminal amino groups of tris(2-aminoethyl)amine (tren) has been prepared, and its protonation constants and stability constants for the formation of Cu(2+) complexes have been determined. Kinetic studies on the formation of Cu(2+) complexes in slightly acidic solutions and on the acid-promoted complex decomposition strongly suggest that the Cu(2+)-L1 complex exists in solution as a mixture of two species, one of them showing a trigonal bipyramidal (tbp) coordination environment with an absorption maximum at 890 nm in the electronic spectrum, and the other one bein…
Cubane-Type CuII4 and MnII2MnIII2 Complexes Based on Pyridoxine: A Versatile Ligand for Metal Assembling
2013
By using Vitamin B6 in its monodeprotonated pyridoxine form (PN-H) [PN = 3-hydroxy-4,5-bis(hydroxymethyl)-2-methylpyridine], two tetranuclear compounds of formula [Mn4(PN-H)4(CH3CO2)3Cl2]Cl·2CH3OH·2H2O (1) and [Cu4(PN-H)4Cl2(H2O)2]Cl2 (2) have been synthesized and magneto-structurally characterized. 1 crystallizes in the triclinic system with space group P1 whereas 2 crystallizes in the orthorhombic system with Fdd2 as space group. They exhibit Mn(II)2Mn(III)2 (1) and Cu(II)4 (2) cubane cores containing four monodeprotonated pyridoxine groups simultaneously acting as chelating and bridging ligands (1 and 2), three bridging acetate ligands in the syn-syn conformation (1), and two terminally …
Oxidation of substituted phenols using copper(II) metallatriangles formed through ligand sharing
2014
Reaction of N(2),N(2')-bis-[(1-butyl-benzimidazol-2yl)methyl]biphenyl-2,2'-dicarboxamide (L) with CuX2⋅nH2O in methanol leads to the assembly of four trinuclear Cu(II) complexes with the general formula [Cu3(L)3X3]⋅3X⋅nH2O⋅mMeCN, where X=Cl(-), Br(-), NO3(-) and C6H5COO(-) and n=0-5, m=0-8 (compounds 1-4, respectively). The structure of one of the complex contains three Cu(II) metal ions at the corners of an equilateral triangle. Each of the copper(II) are coordinated through two benzimidazolyl imine N-atoms and two amide carbonyl O-atoms and the apical position is occupied by an anionic nitrate ion, leading to a distorted square pyramidal environment. The magnetic susceptibility data were …