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P Fons

Publications and source records attributed to P Fons.

6 recordsLinked to original sources
PubMed2006

Pressure-induced site-selective disordering of Ge2Sb2Te5: a new insight into phase-change optical recording.

We demonstrate that , the material of choice in phase-change optical recording (such as DVD-RAM), can be rendered amorphous by the application of hydrostatic pressure. It is argued that this structural change is due to a very strong second-nearest-neighbor Te-Te interaction that determines the long-range order in the metastable cubic phase of and also to the presence of vacancies. This newly discovered phenomenon suggests that pressure is an important factor for the formation of the amorphous phase which opens new insight into the mechanism of phase-change optical recording.

Journal Article↗
PubMed2000

[Anti-angiogenesis strategies in cancer].

It is generally accepted that tumor development requires the secretion by cancer cells of soluble mediators which activate the formation of new vessels, called "Tumor Angiogenic Factors". The intense quest for identifying these factors has recently been confirmed by strong experimental data. The discovery in 1989 of the Vascular Endothelial Growth Factor VEGF and of new proteases had led to the identification of the key actors of tumor angiogenesis. The elucidation of their mechanisms of action allowed to design new therapeutic strategies already confirmed by preclinical trials. There are now almost twenty molecules which are under clinical investigation in man.

Angiogenesis Inducing Agents↗
PubMed1998

Formalistic description of multislice calculation method.

This paper presents a formalistic description of the multislice method. The effects of the number of beams, the number of Fourier components for the projected potential used for the phase grating, the number of the iterations and the slice thickness on multislice calculations are discussed qualitatively. The phenomenon of "leaking" of the wave function to higher order reflections in reciprocal space in a multislice calculation is also discussed. The relationship between the number of Fourier components of the projected potential and the number of beams used for the wave function in reciprocal space is discussed. Additionally, the difference between the eigenvalue method and the multislice method is introduced. The difference between the use of the Fourier transformation vs. the convolution in reciprocal space on multislice calculations is also discussed. Multislice computer simulations were carried out using the commercial program Cerius2 for rutile TiO2. Calculated results are compared with the results of other programs reported in the literature. The effect of slice thickness of the multislice calculation is also shown.

Fourier Analysis↗
PubMed1997

Overexpression of DNA polymerase beta sensitizes mammalian cells to 2',3'-deoxycytidine and 3'-azido-3'-deoxythymidine.

Mammalian DNA polymerase beta is a DNA repair enzyme expressed constitutively at a low level. In vitro, purified DNA polymerase (Pol) beta incorporates the nucleotide analogues 2'-3' deoxycytidine (ddC)-triphosphate and 3'-azido-3'-deoxythymidine (AZT)-triphosphate into DNA, causing chain termination. We have tested the possibility of enhancing the cytotoxicity of these chain terminators against mammalian cells by increasing the level of Pol beta. Chinese hamster ovary AA8 and murine melanoma B16 cell lines were stably transfected with rat pol beta cDNA under the control of a viral enhancer/promoter. We found that overexpression of Pol beta sensitized the cells to ddC and AZT. To confirm the role of this polymerase in this process, we prepared cell extracts from the control and Pol beta overexpressing Chinese hamster ovary cell lines and tested in vitro their capacity to incorporate ddC-triphosphate and AZT-triphosphate into DNA. We found that inhibition of DNA replication by both chain terminators was more pronounced when extracts from pol beta-transfected cells were used, providing a direct evidence of the involvement of Pol beta in the sensitization process. In addition, we showed that cotransfection with bacterial or viral thymidine/thymidylate kinase genes enhanced the Pol beta-mediated cytotoxicity of AZT, suggesting that phosphorylation and polymerization activities might be combined to potentiate their respective effects. These observations may be useful for improving therapeutic efficiency of DNA chain terminators.

Animals↗