PubMed Health⌕ Search

Biomedical subjects

V Bustos

Publications and source records attributed to V Bustos.

5 recordsLinked to original sources
PubMed2006

Dynamic Monte Carlo simulation of the NO + CO reaction on Rh(111).

The kinetics of the catalytic reduction of NO by CO on Rh(111) surfaces was investigated by using dynamic Monte Carlo simulations. Our model takes into account recent experimental findings and introduces relevant modifications to the classical reaction scheme, including an alternative pathway to produce N2 through an (N-NO)* intermediate, the formation of atomic nitrogen islands in the adsorbed phase, and the influence of coadsorbed species on the dissociation of NO. All elementary steps are expressed as activated processes with temperature-dependent rates and realistic values dictated by experiments. Calculated steady-state phase diagrams are presented for the NO + CO reaction showing the windows for the conditions under which the reaction is viable. The model predicts variations in both production rates and adsorbate coverages with temperature consistent with experimental data. The effect of varying the individual kinetic parameters and the importance of each step in the reaction scheme were probed.

Journal Article↗
PubMed2000

Kinetic phase transitions in a contaminated monomer-dimer reaction model

The irreversible kinetics of a monomer-dimer reaction on a catalyst surface [the Ziff-Gulari-Barshad (ZGB) model] in the presence of a contaminant species is studied by means of Monte Carlo simulation. The only processes allowed to the contaminant are adsorption and desorption; it is otherwise inert. The reaction window, delimited by a second order irreversible phase transition at low monomer concentration (lower bound transition) and by a first order one at high monomer concentration (upper bound transition) in the ZGB model is found to shrink with increasing contaminant concentration in a way that depends on its adsorption-desorption kinetics. Through epidemic analysis, it is also found that the upper bound transition changes from first to second order and that the lower bound transition can also be affected depending on the contaminant adsorption-desorption kinetics. The results may provide alternative explanations for experimental observations.

Journal Article↗
PubMed1998

Propagation of genetically altered tumor cells derived from fine-needle aspirates of primary breast carcinoma.

Because primary breast tumors are diagnosed earlier in the clinic, procurement of sufficient amounts of tumor tissue for in-depth biological characterization is becoming increasingly difficult. We demonstrate here that relatively small numbers of tumor cells within samples of fine-needle aspirates (FNA) can be propagated in culture. Of 25 cases attempted, 12 were passageable, resulting in up to 10(7) viable cells. FNA-derived cultures were evaluated for anchorage-independence, c-erb-B2 overexpression, aneusomy, and pattern of allelic loss. In every case examined, the cultured cells closely resembled the original tumor tissue and displayed one or more tumor phenotypes. The incidence of erb-B2 overexpressing tumors was similar in passageable and nonpassageable cases (33% versus 31%, respectively). FNAs that are expanded from a wide range of clinical breast material could be useful for functional studies presently limited to rare established cell lines, such as aberrant signal transduction and gene regulation, and for testing potential anticancer vaccines and drugs.

Biopsy, Needle↗