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G Stan

Publications and source records attributed to G Stan.

8 recordsLinked to original sources
PubMed2000

Condensation of helium in nanotube bundles

Helium atoms are strongly attracted to the interstitial channels within a bundle of carbon nanotubes. The strong corrugation of the axial potential within a channel can produce a lattice gas system wherein the weak mutual attraction between atoms in neighboring channels induces a transition to an anisotropic condensed phase. At low temperatures, the specific heat of the adsorbate phase (with fewer than 2% of the atoms) greatly exceeds that of the host.

Journal Article↗
PubMed2000

Threshold criterion for wetting at the triple point

Grand canonical simulations are used to calculate adsorption isotherms of various classical gases on alkali metal and Mg surfaces. Ab initio adsorption potentials and Lennard-Jones gas-gas interactions are used. Depending on the system, the resulting behavior can be nonwetting for all temperatures studied, complete wetting, or (in the intermediate case) exhibit a wetting transition. An unusual variety of wetting transitions at the triple point is found in the case of a specific adsorption potential of intermediate strength. The general threshold for wetting near the triple point is found to be close to that predicted with a heuristic model of Cheng et al. This same conclusion was drawn in a recent experimental and simulation study of Ar on CO2 by Mistura et al. These results imply that a dimensionless wetting parameter w is useful for predicting whether wetting behavior is present at and above the triple temperature. The nonwetting/wetting crossover value found here is w approximately 3.3.

Journal Article↗
PubMedDate not supplied

[Association between phakomatosis and neoplasia in children pathology. IV Pediatric Clinic experience].

The risk to developing a neoplasm is increased when associated to a patient phakomatosis (Recklinghausen neurofibromatosis, Bourneville's tuberous sclerosis). We analysed 6 cases with phakomatosis and tumours, admitted in the Department of Oncopediatry, between 1993-1998; five of these children had neurofibromatosis and one Bourneville's disease. The associated tumours were hematologic malignancies (juvenile myeloid chronic leukemia) and solid tumors (rhabdomyosarcoma, hepatic carcinoma, CNS tumour, NHL optic glioma). The diagnosis was confirmed by microscopic examination of the bioptic material in all cases. Tumoral staging was performed by clinics, biology and imagistic investigations. All cases had extensive and aggressive tumours at the moment of diagnosis, We noticed a poor response and an early relapse after chemotherapy. A special follow-up and a different management has to be established for the patients with phakomatosis, in order to have a good oncological prophylaxis.

Adolescent↗