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Time-resolved detection of field-free molecular alignment is investigated by phase contrast. The technique based on a 4 f imager operating as an inverted Zernike spatial filter makes it possible to discriminate between positive and negative molecular alignment revivals produced in a linear molecule. The measurements are performed in a way that minimizes the contamination of the signal by the plasma generated during the aligning pulse. The observations are supported by a semi-analytical model, from which the degree of alignment produced at the beam focus is estimated. [ABSTRACT FROM AUTHOR]

We demonstrate the generation of a persistent planar molecular alignment by subjecting a relatively warm gas sample to a resonant femtosecond laser pulse. By optically probing I_{2} molecules in their vibronic ground states, we observe a persistent delocalization of their axes near the plane orthogonal to the field direction. This phenomenon is attributed to the one-photon resonant excitation, primarily removing molecules from the thermal ground-state distribution that are initially aligned along the field, i.e., those with small projection of their rotational angular momentum along the field.

We present a model for the lowest two potential energy surfaces (PESs) that describe the photoinduced ring-opening reaction of benzopyran taken as a model compound to study the photochromic ring-opening reaction of indolinobenzospiropyran and its evolution toward its open-chain analog. The PESs are expressed in terms of three effective rectilinear coordinates. One corresponds to the direction between the equilibrium geometry in the electronic ground state, referred to as the Franck-Condon geometry, and the minimum of conical intersection (CI), while the other two span the two-dimensional branching space at the CI. The model correctly reproduces the topography of the PESs. The ab initio calculations are performed with the extended multiconfiguration quasidegenerate perturbation theory at second order method. We demonstrate that accounting for electron dynamic correlation drastically changes the global energy landscape since some zwitterionic states become strongly stabilized. Quantum dynamics calculations using this PES model produce an absorption spectrum that matches the experimental one to a good accuracy.

We report on the polarization analysis of shortpulse ultraviolet radiation produced by third-harmonic generation in a gas of coherently spinning molecules. A pulse of twisted linear polarization imprints a unidirectional rotational motion to the molecules leading to an orientation of their rotational angular momenta. A second pulse, time-delayed with respect to the first one, circularly polarized in the plane of rotation of the molecules, acts as a driving field for third-harmonic generation. The angular momentum and energy conservation applied to this process foresees the generation of two Doppler-shifted circularly-polarized harmonics of opposite handedness. Our analysis reveals that spinning molecules enable the generation of a well polarized third-harmonic radiation exhibiting a high degree of ellipticity. Tracking the orientation of the latter allows a time-capture of the molecular axis direction from which the average angular velocity of the rotating molecules is inferred. This method provides a user-friendly polarization-based tachometer for measurement of the rotational speed of spinning nonlinear rotors.

We demonstrate a polarized all-normal dispersion supercontinuum generated in a birefringent silica microstructured fiber spanning beyond 2.5 µm. To our knowledge, this is the spectra reaching the furthest in mid-infrared ever generated in normal dispersion silica fibers. The generation process was studied experimentally and numerically with 70 fs pump pulses operating at different wavelengths on short propagation distances of 48 mm and 122 mm. The all-normal operation was limited by the zero-dispersion wavelength at 2.56 µm and spectral broadening was stopped by OH absorption peak at 2.72 µm. We identified the asymmetry between propagation in both polarization axes and showed that pumping along a slow fiber axis is beneficial for a higher degree of polarization. Numerical simulations of the generation process conducted by solving the generalized nonlinear Schrödinger equation (NLSE) and coupled NLSEs system showed good agreement with experimental spectra.

We report herein a versatile cooperative dual catalysis reaction based on a Cu(I)/Pd(0) system. Mechanistic investigation shows that every component plays a crucial role in determining the reaction outcome. The reaction is successfully extended to various substrates; such as α,β-unsaturated ketones, malonates and coumarins. The strategy tolerates different substitution patterns and affords good yields for each family of substrates., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A new modification of Julia-Kocienski olefination reaction based on the use of cation-specific chelating agents that yields 1,3-dienes with predictable (E/Z)-selectivity on newly created double bond was developed. The influence of the aldehyde structure on reaction (E/Z) selectivity is discussed and rationalized.

Transverse "chemical" interfaces are revealed with a conventional two beam narrowband coherent anti-Stokes Raman scattering microscopy setup in a collinear configuration. The exciting "pump" and "Stokes" beams are focused on the sample in two opposite directions. The subtraction of the two generated anti-Stokes signals gives rise to a signal that is directly proportional to the pure Raman spectrum of the resonant medium. This property is used to highlight an interface between glass and N,N-dimethylformamide (DMF) and recover the pure Raman spectrum of DMF around its 1408 cm(-1) vibrational band.

We study tight focus coherent anti-Stokes Raman scattering (CARS) emission in a microcavity where the active medium is squeezed between two independent planar mirrors. We show strong modifications in the CARS forward and backward far-field radiation patterns. For low-order cavities, we demonstrate that most of the emitted power can be concentrated into a direction perpendicular to the mirrors.

We present the results of Z-scan studies carried out on fused silica at 1064nm and 532nm with two different nanosecond pulse durations. Such measurements in silica and in the nanosecond regime are possible thanks to a high sensitivity setting up of the Z-scan method and in-situ characterizations of the spatio-temporal parameters of the beam. Besides, with the use of a newly adapted numerical simulation only the calibration errors of the measurement devices are significant. In these conditions, we found a higher value of the nonlinear refractive index than in the femtosecond regime and we show that these values depend on pulse duration, which indicates the contribution of nanosecond mechanisms like electrostriction.

Capsular tumors of the kidney are uncommon or poorly documented. The authors report two cases of benign vascular tumors: a so-called "vascular leiomyoblastoma" and a glomus tumor. An ultrastructural study of the first tumor demonstrated smooth muscular characteristics. Obvious histological features of glomus were seen in the second. Immunohistochemical study revealed positive immunoreactivity for epithelial and mesenchymal antibodies in the two tumors. Glomus tumor originates from the particular system of vessels in the capsule. Histogenesis of the vascular leiomyoblastoma is more controversial. This tumor could be akin to leiomyomas of the renal capsule and intra parenchymatous leiomyomas; lymphatic origin and even a glomangiomatous nature are also possible explanations.

The generalized use of phosphocalcic biological assays makes the discovery of sporadic primary hyperparathyroidism increasingly common. In 1989-1990, first-intention surgery was performed in 26 female patients. In all cases, an exploratory cervicotomy under cervical peridural anesthesia allowed discovering and treating a parathyroid lesion: adenoma, asymmetric or symmetric hyperplasia, cancer. We discuss: the circumstances of the clinical diagnosis and the biological criteria, the timeliness of preoperative radiological assessment, the surgical strategy advocated. In more than 90% of all cases, a cervicotomy for the exploration of all areas of parathyroid migration should allow curing primary hyperparathyroidism.

Parathyroid hormone (PTH) and chromogranin A/secretory protein-I (SP-I) have been localized on immunoelectron microscopy in double-fixed tissues from adenomatous and secondary hyperplastic parathyroid glands. Storage organelles, identified on the basis of their consistent labelling, included tow morphologically distinct varieties of granules/vesicles; the mature granules and the progranules. The former consisted of dense, mostly rounded, medium to large-sized bodies which were strongly labelled and predominant in the proximity of the cell membrane. The other variety of body included a spectrum of small pale vesicles/granules which were mainly located in the Golgi area. Because their morphology and their labelling pattern varied other bodies were assumed to be engaged in degradation or cleavage of the secretory proteins. These bodies comprised crinophagic structures, that is to say multivesicular bodies and large Golgi-related vesicles, as well as a number of atypical solid bodies. Whereas most of the granulated cells stored a mature or a maturing population of vesicles/granules, the process of maturation appeared to be either absent or incomplete in a number of cells from some glands. The major defects were frequently associated with an unusual labelling pattern of the Golgi area and selectively affected groups of cells from all the transitional oxyphil cell adenomas. The minor defects concerned individual cells of different types present in both categories of glands. The present data suggest that in hyperfunctioning glands, the type of hormone processing depends on the capacity of each cell in progranule maturation and that the maturation capacity may decrease dramatically in adenomatous or chronically hyperstimulated cells of the transitional oxyphil type.