Biomedical subjects

Filip Uhlík

Publications and source records attributed to Filip Uhlík.

4 recordsLinked to original sources

PubMed2006

Computed structures of two known Yb@C74 isomers.

Six isomers of Yb@C74 are considered, namely one cage with isolated pentagons, three isomers with a pentagon-pentagon junction, two structures with one pentagon-pentagon pair, and one heptagon. The computations based on the Gibbs energy point out the endohedral derived from the only C74 cage with the isolated pentagons and from a cage with one pentagon-pentagon junction as the major and minor observed isomer, respectively. Temperatures giving the best agreement with the experimental production ratio are evaluated.

Journal Article↗

PubMed2006

La2@C72 and Sc2@C72: computational characterizations.

The La2@C72 and Sc2@C72 metallofullerenes have been characterized by systematic density functional computations. On the basis of the most stable geometry of 39 C72 hexaanions and the computed energies of the best endofullerene candidates, the experimentally isolated La2@C72 species was assigned the structure coded #10611. The good agreement between the computed and the experimental 13C chemical shifts for La2@C72 further supports the literature assignment (Kato, H.; Taninaka, A.; Sugai, T.; Shinohara, H. J. Am. Chem. Soc. 2003, 125, 7782). The geometry, IR vibrational frequencies, and 13C chemical shifts of Sc2@C72 were predicted to assist its future experimental characterization.

Journal Article↗

PubMed2004

Polyelectrolyte shells of copolymer micelles in aqueous solutions: a Monte Carlo study.

Multimolecular micelles, formed by polystyrene-block-poly(methacrylic acid) in water, are studied by lattice Monte Carlo method. Electrostatic interactions are calculated in the mean-field approximation by solving the Poisson-Boltzmann equation. The model is parametrized according to available experimental data. The dependence of micellar size on pH and ionic strength is calculated and compared with experimental data. A special attention is devoted to the behavior in solutions with a low ionic strength.

Journal Article↗

PubMed2003

Computations of model narrow nanotubes closed by fragments of smaller fullerenes and quasi-fullerenes.

New type of carbon nanotubes-narrow nanotubes-has recently been observed with diameters of 4-5 A. It has been postulated that the narrow nanotubes are closed by fullerene fragments of C(20) and C(36). This paper presents computational results on related model nanotubes with stoichiometries such as C(80), C(84), C(96), C(108), or C(120). The computations were carried out at the PM3, AM1, SAM1, HF/3-21G, HF/4-31G, and B3LYP/6-31G(*) levels. Two C(36) fullerenes were considered, D(6h) and D(2d). At the PM3 level and with the C(84) nanotube stoichiometry, the D(2d) cage closure gave a lower energy (by 185 kcal/mol and a diameter of 5.42 A). There is another possible candidate, a C(32) cage with D(4d) symmetry (two four-membered rings). At the PM3 level and with the C(96) nanotube stoichiometry, the D(4d) closure (with a diameter of 5.43 A) had energy lower by 210 kcal/mol than that of the D(6h) nanotube closure. On the other hand, four-membered rings should not play a significant role for narrow nanotubes with a diameter of 4 A, where the dodecahedron-related closure should be exclusive. Still narrower nanotubes are briefly discussed.

Fullerenes↗