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H Saadaoui

Publications and source records attributed to H Saadaoui.

9 recordsLinked to original sources
PubMed2006

Near-surface structural phase transition of SrTiO3 studied with zero-field beta-detected nuclear spin relaxation and resonance.

We demonstrate that zero-field beta-detected nuclear quadrupole resonance and spin relaxation of low energy (8)Li can be used as a sensitive local probe of structural phase transitions near a surface. We find that the transition near the surface of a SrTiO(3) single crystal occurs at T(c) approximately 150K, i.e., approximately 45K higher than T(c)bulk, and that the tetragonal domains formed below T(c) are randomly oriented.

Journal Article↗
PubMed2005

Microarrays of near-field optical probes with adjustable dimensions.

We present the fabrication and the characterization of high-density microarrays comprising thousands of near-field optical probes. Two types of microarrays have been prepared by adapting the SNOM methodology: arrays of uncoated fiber nanotips (i.e. apertureless probes) and arrays of apertures with adjustable subwavelength dimensions. Such arrays were fabricated by retaining the coherent structure of monomode optical fiber bundles and therefore keeping their imaging properties. The size of the apertures in a microarray was tuned at the nanometer scale by modifying the fabrication parameters. Far-field characterization of these near-field probe arrays shows completely different behavior depending both on their architecture and on their characteristic size. The angular distribution of the far-field intensity transmitted through the aperture arrays is used to determine the optical size of such diffracting apertures. Aperture radii ranging from 95 to 250 nm were found in good agreement with SEM data. Furthermore, each nanoaperture of the array is optically independent in the far-field regime. Eventually, this study demonstrates potential applications of these imaging arrays as parallel near-field optical probes in both configurations (apertureless and with apertures).

Journal Article↗
PubMed2004

Role of interfacial effects in carbon nanotube/epoxy nanocomposite behavior.

The interfacial effects are critical to understand the nanocomposite behavior based on polymer matrices. These effects are dependent upon the morphology of carbon nanotubes, the type of used polymer and the processing technique. Indeed, we show that the different parameters, as the eventual surfactant use, the ultrasonic treatment and shear mixing have to be carefully examined, in particular, for nanotube dispersion and their possible alignment. A series of multiwalled nanotubes (MWNT) have been mixed with a regular epoxy resin under a controlled way to prepare nanocomposites. The influence of nanotube content is examined through helium bulk density, glass transition temperature of the matrix and direct current electrical conductivity measurements. These results, including the value of the percolation threshold, are analyzed in relationship with the mesostructural organization of these nanotubes, which is observed by standard and conductive probe atomic force microscopy (AFM) measurements. The wrapping effect of the organic matrix along the nanotubes is evidenced and analyzed to get a better understanding of the final composite characteristics, in particular, for eventually reinforcing the matrix without covalent bonding.

Adsorption↗
PubMed1996

[Multiple congenital tarsal synostoses].

Tarsal coalition is an abnormal fusion of two or more tarsal centers. Talo-calcaneal and calcaneo-navicular coalition are the most frequent types. If multiple tarsal coalition is suspected, computed tomography with sagittal reconstruction is the best method for diagnosis.

Adult↗
PubMed1996

[Contribution of imaging in intestinal intussusception in the adult. Apropos of a case of ileocolic intussusception secondary to cecal lipoma].

On the basis of a case of ileocolonic intussusception in a 35-year-old patient secondary to an obstructive lipoma of the caecum, the authors review the literature and discuss the clinical and radiological aspects of this disease. The diagnosis was established by CT scan and barium enema before surgery. Adult intussusception is a rare disease, which does not have any specific clinical features. Radiological imaging is the only complementary investigation which can suggest the diagnosis.

Abdominal Pain↗