In vitro sonodynamic cytotoxicity in regulated cavitation conditions

Sonodynamic toxicity has always been linked to the cavitation phenomenon. In this work, sonodynamic effect with Photofrin^® was evaluated with a new ultrasound device: a regulated cavitation generator. In this way, acoustic intensity was substituted with cavitation level as ultrasound parameter. Photofrin^® potentiated significantly the cavitation cytotoxicity even for low setpoints where no inertial cavitation appeared. Therefore sonodynamic mechanism was principally mechanical, facilitated by the Photofrin^® insertion in cellular cytoplasmic membranes. This assertion was also supported by the fact that sonodynamic cytotoxicity was independent from the Photofrin^® presence or absence in the extracellular medium. Reproducible sonodynamic efficiency was perfectly obtained with this new regulated cavitation generator.     

Very first tests on SOLEIL regarding the Zn environment in pathological calcifications made of apatite determined by X‐ray absorption spectroscopy

This very first report of an X‐ray absorption spectroscopy experiment at Synchrotron SOLEIL is part of a long‐term study dedicated to pathological calcifications. Such biological entities composed of various inorganic and/or organic compounds also contain trace elements. In the case of urinary calculi, different papers already published have pointed out that these oligo‐elements may promote or inhibit crystal nucleation as well as growth of mineral. Use of this analytical tool specific to synchrotron radiation, allowing the determination of the local environment of oligo‐elements and thus their occupation site, contributes to the understanding of the role of trace elements in pathological calcifications.     

Excimer laser-induced crystallization of CdSe thin films

We have investigated ArF (λ=193 nm) excimer laser-induced crystallization of amorphous CdSe semiconductor thin films. The crystallization has been monitored by a related photoluminescence emission in the free-exciton and defect-band transition regions. For different irradiation conditions, we have observed formation of nanorods, up to 2 μm long, as well as the formation of arrays of CdSe nanobeads with a narrow size distribution and characteristic dimensions corresponding to λ/2 and λ/8. The successful crystallization has also been confirmed by confocal Raman spectroscopy.     

Local vibration of an elastic plate and zero-group velocity Lamb modes

Elastic plates or cylinders can support guided modes with zero group velocity (ZGV) at a nonzero value of the wave number. Using laser-based ultrasonic techniques, we experimentally investigate some fascinating properties of these ZGV modes: resonance and ringing effects, backward wave propagation, interference between backward and forward modes. Then, the conditions required for the existence of ZGV Lamb modes in isotropic plates are discussed. It is shown that these modes appear in a range of Poisson's ratio about the value for which the cutoff frequency curves of modes belonging to the same family intercept, i.e., for a bulk wave velocity ratio equal to a rational number. An interpretation of this phenomenon in terms of a strong repulsion between a pair of modes having a different parity in the vicinity of the cutoff frequencies is given. Experiments performed with materials of various Poisson's ratio demonstrate that the resonance spectrum of an unloaded elastic plate, locally excited by a laser pulse, is dominated by the ZGV Lamb modes.     

Magic features of 68Ni

From measurements of the angular distribution around 0° for the ⁷⁰Zn(¹⁴C, ¹⁶O) reaction, the first excited state of ⁶⁸Ni observed at 1.77 ± 0.04 MeV is shown to be 0⁺. This result establishes a new case of 2⁺₁ and 0⁺₂ inversion.     

Periodic structure at the free surface of smectics A

We observe at the free surface of several smectics A in a hoeizontal magnetic field H a periodic focal conic texture. The period varies roughly as 1/H.     

Core-electron relaxation energy in small metallic particles

A general calculation method for screening in a finite electron gas proposed by Cini, is applied to study of core-hole relaxation energy in small metallic particles. In order to obtain quantitative results, a pseudopotential theory is developed for the core-hole perturbation which provides excellent agreement with the generally accepted excited-atom model in the bulk limit. The transition and noble metals treated by means of a semi-empirical extension of the method. The present calculation method of extra-atomic relaxation energies, involving an electron gas approximation for the conduction electrons allows straightforward applications of the method of Cini in the case of a finite-spherical metal particle. The relaxation energy is found to give an important contribution to core-hole binding energy shifts in small particles.     

The complex transfer reaction (14C, 15O) on Ni,Zn and Ge targets: Existence and mass of 69Ni

The (¹⁴C, ¹⁵O) complex transfer reaction has been studied at 72 MeV incident energy on ^58,60,62.64Ni ^68,70Zn and ^74,76Ge targets. Spectra and differential cross sections have been measured in a 5° angular range centred around a laboratory angle of 6°. The nucleus ⁶⁹Ni has been observed for the first time and its mass determined.     

Anisotropy of the turbidity of a nematic liquid crystal

The absorption coefficient of a nematic liquid present an important anisotropy. The measurement of this coefficient in three simple geometries allows the determination of the three Frank elastic constants on the same sample. We give the results obtained for MBBA at room temperature.