186 research outputs found
Convergence of the Crank-Nicolson-Galerkin finite element method for a class of nonlocal parabolic systems with moving boundaries
The aim of this paper is to establish the convergence and error bounds to the
fully discrete solution for a class of nonlinear systems of reaction-diffusion
nonlocal type with moving boundaries, using a linearized
Crank-Nicolson-Galerkin finite element method with polynomial approximations of
any degree. A coordinate transformation which fixes the boundaries is used.
Some numerical tests to compare our Matlab code with some existing moving
finite elements methods are investigated
EP20.01: Twin pregnancy birth in a new non-tertiary hospital
info:eu-repo/semantics/publishedVersio
Influence of the sterol aliphatic side chain on membrane properties: a molecular dynamics study
Following a recent experimental investigation of the effect of the length of the alkyl side chain in a series
of cholesterol analogues (Angew. Chem., Int. Ed., 2013, 52, 12848–12851), we report here an atomistic
molecular dynamics characterization of the behaviour of methyl-branched side chain sterols (iso series) in
POPC bilayers. The studied sterols included androstenol (i-C0-sterol) and cholesterol (i-C8-sterol), as well
as four other derivatives (i-C5, i-C10, i-C12 and i-C14-sterol). For each sterol, both subtle local effects and
more substantial differential alterations of membrane properties along the iso series were investigated. The
location and orientation of the tetracyclic ring system is almost identical in all compounds. Among all the
studied sterols, cholesterol is the sterol that presents the best matching with the hydrophobic length of
POPC acyl chains, whereas longer-chained sterols interdigitate into the opposing membrane leaflet. In
accordance with the experimental observations, a maximal ordering effect is observed for intermediate
sterol chain length (i-C5, cholesterol, i-C10). Only for these sterols a preferential interaction with the
saturated sn-1 chain of POPC (compared to the unsaturated sn-2 chain) was observed, but not for either
shorter or longer-chained derivatives. This work highlights the importance of the sterol alkyl chain in the
modulation of membrane properties and lateral organization in biological membranes
A supramolecular zigzag chain of organometallic dipoles mediated by PF6 2- anions
Complex {Fe( 5-cyclopentadienyl)(PMe3)[P(OPh)3](4–NCC6H4NO2)} [PF6] has been characterized
by spectroscopic and X-ray diffraction in order to evaluate the tuning of the electron
density at the metal center and the extension ofthe delocalization on the molecule due to the
presence of phosphite and phosphine co-ligands. The compound crystallizes in the centrosymmetric
space group P21/c which destroys the possibility of exhibiting any quadratic NLO properties.
The packing shows a supramolecular zigzag chain of antiparalell dimmers connected via the PF6
anions with C—H—F −distances ranging from 2.389 (7) to 2.667 (6)°A . Each zigzag chain is
composed by isomeric organometallic fragments containing either R or S molecules. These chains
are connected through weak intermolecular interactions (C—H· · ·C) forming a two dimensional
plane along [101]
A supramolecular zigzag chain of organometallic dipoles mediated by PF6 2- anions
Complex {Fe( 5-cyclopentadienyl)(PMe3)[P(OPh)3](4–NCC6H4NO2)} [PF6] has been characterized
by spectroscopic and X-ray diffraction in order to evaluate the tuning of the electron
density at the metal center and the extension ofthe delocalization on the molecule due to the
presence of phosphite and phosphine co-ligands. The compound crystallizes in the centrosymmetric
space group P21/c which destroys the possibility of exhibiting any quadratic NLO properties.
The packing shows a supramolecular zigzag chain of antiparalell dimmers connected via the PF6
anions with C—H—F −distances ranging from 2.389 (7) to 2.667 (6)°A . Each zigzag chain is
composed by isomeric organometallic fragments containing either R or S molecules. These chains
are connected through weak intermolecular interactions (C—H· · ·C) forming a two dimensional
plane along [101]
Synthesis of Cyclodextrin Inclusion Complexes with (h-Cyclopentadienyl)iron Derivatives as Potential Nonlinear Optics Materials*
Dicarbonyl(h-cyclopentadienyl)iron tetrafluoroborates containing aromatic nitriles as ligands were
synthesized. These and other (h-cyclopentadienyl)iron derivatives were used to obtain intercalation compounds
with b-cyclodextrin
Synthesis of new donor/acceptor 5-cyclopentadienyl and 5-indenyliron(II) complexes with p-benzonitrile derivatives. Crystal structures of [Fe( 5-C5H5)(CO)(P(OC6H5)3)(p-NCC6H4NO2)][BF4]·CH2Cl2 and [Fe( 5-C9H7)(CO)(P(OC6H5)3)(p-NCC6H4NO2)][BF4]
New complexes of the type [Fe( 5-Cp or Ind)(L)(L )(p-NCR)][BF4] (L, L =CO, P(OC6H5)3, P(C6H5)3; R=C6H4N(CH3)2,
C6H4NO2, (E)-C(H) C(H)C6H4NO2, (E)-C(H) C(H)C6H4N(CH3)2) have been synthesised and characterised. Spectroscopic data
were analysed in order to evaluate the tuning of the electronic density at the metal centre and the extension of the -delocalisation
on the molecule, due to the presence of coligands with different acceptor/donor abilities. The structures of two complexes
[Fe( 5-C5H5)(CO)(P(OC6H5)3)(p-NCC6H4NO2)][BF4] and [Fe( 5-C9H7)(CO)(P(OC6H5)3)(p-NCC6H4NO2)][BF4] were determined
by X-ray crystallographic analysis. The compounds crystallised in the centrosymmetric space groups P1 and P21/n, respectively.
Bond distances within the nitrile ligand are discussed in order to evaluate the nature of iron–nitrile bonding in these complexes
Conventional vs. Microwave-or mechanically-assisted synthesis of dihomooxacalix[4]arene phthalimides: NMR, X-ray and photophysical analysis
Direct O-alkylation of p-tert-butyldihomooxacalix[4]arene (1) with N-(bromopropyl)-or N-(bromoethyl)phthalimides and K2 CO3 in acetonitrile was conducted under conventional heating (reflux) and using microwave irradiation and ball milling methodologies. The reactions afforded mono-and mainly distal di-substituted derivatives in the cone conformation, in a total of eight compounds. They were isolated by column chromatography, and their conformations and the substitution patterns were established by NMR spectroscopy (1 H,13 C, COSY and NOESY experiments). The X-ray structures of four dihomooxacalix[4]arene phthalimide derivatives (2a, 3a, 3b and 5a) are reported, as well as their photophysical properties. The microwave (MW)-assisted alkylations drastically reduced the reaction times (from days to less than 45 min) and produced higher yields of both 1,3-di-substituted phthalimides (3a and 6a) with higher selectivity. Ball milling did not reveal to be a good method for this kind of reaction
Studies of the Antiproliferative Activity of Ruthenium (II) Cyclopentadienyl-Derived Complexes with Nitrogen Coordinated Ligands
Four cationic ruthenium(II) complexes with the formula [Ru(η5-C5H5)(PPh3)2]+, with L = 5-phenyl-1H-tetrazole (TzH) 1, imidazole (ImH) 2, benzo[1,2-b;4,3-b′] dithio-phen-2-carbonitrile (Bzt) 3, and [5-(2-thiophen-2-yl)-vinyl]-thiophene-2-carbonitrile] (Tvt) 4 were prepared and characterized in view to evaluate their potentialities as antitumor agents. Studies by Circular Dichroism indicated changes in the secondary structure of ct-DNA. Changes in the tertiary structure of pBR322 plasmid DNA were also observed in gel electrophoresis experiment and the images obtained by atomic force microscopy (AFM) suggest strong interaction with pBR322 plasmid DNA; the observed decreasing of the viscosity with time indicates that the complexes do not intercalate between DNA base pairs. Compounds 1, 2, and 3 showed much higher cytotoxicity than the cisplatin against human leukaemia cancer cells (HL-60 cells)
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