Spatial and temporal properties of parametric fluorescence around degeneracy in a type I LBO crystal

We present a theoretical and experimental study of the spatio-temporal properties of the spontaneous parametric emission generated in a type I LBO crystal around degeneracy. The number of quasi-phase-matched modes is shown to be equal to the number of spatio-temporal degrees of freedom of the image that can be parametrically amplified. From this number, we demonstrate the possibility of predicting the total number of photons generated by parametric fluorescence. Correlation is observed between spatial intensity fluctuations corresponding to pairs of signal-idler modes. Received 18 February 1999 and Received in final form 9 June 1999     

Plasmonic coherent drive of an optical trap

We demonstrate that optical trapping can be driven by delocalized surface plasmon modes resonantly excited within a standing wave trap. Dynamical modifications are shown to be determined by the near-field symmetry of the plasmonic modes with negligible thermal effect. With low trapping powers and polarization control, remarkable stiffness enhancements are recorded, the larger the smaller the particle. The results can be simply modeled accounting for a coherent interaction between the plasmon field and the Gaussian standing wave of the trap.     

Self-collimation of surface plasmon beams

We generate self-collimating surface plasmon beams in a doubly periodic plasmonic grating. The self-collimation effect is understood from the local anisotropy of the isofrequency surface of the grating in the vicinity of the bandgap. The properties of the beams are analyzed by leakage radiation microscopy and show to an unprecedented level significantly reduced diffraction as compared with plasmon beams propagating on a flat metal film.     

Pp IX Silica Nanoparticles Demonstrate Differential Interactions with In Vitro Tumor Cell Lines and In Vivo Mouse Models of Human Cancers

Protoporphyrin IX (Pp IX) silica nanoparticles, developed for effective use in photodynamic therapy (PDT), were explored in in vitro and in vivo models with the ambition to improve knowledge on the role of biological factors in the photodamage. Pp IX silica nanoparticles are found efficient at temperature with extreme metabolic downregulation, which suggest a high proportion of passive internalization. For the first time, clearance of silica nanoparticles on tumor cells is established. Cell viability assessment in six tumor cell lines is reported. In all tumor types, Pp IX silica nanoparticles are more efficient than free Pp IX. A strong fluorescence signal of reactive oxygen species generation colocalized with Pp IX silica nanoparticles, correlates with 100% of cell death. In vivo studies performed in HCT 116, A549 and glioblastoma multiforme tumors-bearing mice show tumor uptake of Pp IX silica nanoparticles with better tumor accumulation than the control alone, highlighting a high selectivity for tumor tissues. As observed in in vitro tests, tumor cell type is likely a major determinant but tumor microenvironment could more influence this differential time accumulation dynamic. The present results strongly suggest that Pp IX silica nanoparticles may be involved in new alternative local applications of PDT.     

Identification of free radicals trapped in solid methacrylated resins

Photopolymerization of methacrylated dental resins at room temperature leads to the appearance of long‐life free radicals because of system vitrification. These free radicals were observed by electronic paramagnetic resonance (EPR), and their characterization was undertaken by reference to the reactional mechanism, from the comparison with the model EPR signal and from theoretical simulation. Overlapping of two EPR signals assigned to two different kinds of radicals because of methacrylate end groups accounted for all the experimental and theoretical results. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1691–1699, 2003     

Retrieval of spatial shot-noise in the full dynamic range of calibrated CCD cameras

The pixel by pixel calibration of a scientific CCD camera allows Poissonian statistics of the spatial fluctuations of an uniform enlightening to be retrieved in the full range of the camera dynamic. The procedure works efficiently for thermal as well as for laser sources, provided that the wavelength and the coherence properties of the source are chosen in order to avoid the formation of equal thickness fringes in the chip (etaloning effect). Calibration allows also the comparison at the shot noise level of images recorded at different places on the chip. Received 9 September 2002 / Received in final form 16 October 2002 Published online 21 January 2003     

Glas

Analytical and Bioanalytical Chemistry -     

Glas

Ohne Zusammenfassung     

Evidence for radial flow of thermal dileptons in high-energy nuclear collisions

The NA60 experiment at the CERN SPS has studied low-mass dimuon production in 158A GeV In-In collisions. An excess of pairs above the known meson decays has been reported before. We now present precision results on the associated transverse momentum spectra. The slope parameter Teff extracted from the spectra rises with dimuon mass up to the rho, followed by a sudden decline above. While the initial rise is consistent with the expectations for radial flow of a hadronic decay source, the decline signals a transition to an emission source with much smaller flow. This may well represent the first direct evidence for thermal radiation of partonic origin in nuclear collisions.