Conformational Landscape of the 1/1 Diacetyl/Water Complex Investigated by Infrared Spectroscopy and ab Initio Calculations.

The complexes of diacetyl with water have been studied experimentally by Fourier transform infrared (FTIR) spectroscopy coupled to solid neon matrix and supersonic jet, and anharmonic ab initio calculations. The vibrational analysis of neon matrix spectra over the 100-7500 cm infrared range confirms the existence of two nearly isoenergetic one-to-one (1/1) diacetyl-water S and S isomers already evidenced in a previous argon matrix study. A third form (S) predicted slightly less stable ( J.

Topological insights into the 1/1 diacetyl/water complex gained using a new methodological approach.

The 1/1 diacetyl/water complex is of atmospheric relevance. Previous experimental and theoretical studies have focused on two isomeric forms, and geometry optimizations were carried out on them. Herein, we propose a six-step methodological approach based on topological properties to search for and characterize all of the isomeric forms of the 1/1 noncovalent diacetyl/water complex: (1) a molecular electrostatic potential (MESP) study to get an overview of the V min and V max regions on the molecular surfaces of the separate molecules (diacetyl and water); (2) a topological (QTAIM and ELF) study allowing thorough characterization of the electron densities (QTAIM) and irreducible ELF basins of the separate molecules; (3) full optimization of the predicted structures based on the interaction between complementary reaction sites; (4) energetic characterization based on a symmetry-adapted perturbation theory (SAPT) analysis; (5) topological characterization of the optimized complexes; (6) analysis of the complexes in terms of orbital overlaps (natural bond orbitals, NBO analysis).

Polarization control in spun and telecommunication optical fibers.

We consider the counterpropagating interaction of a signal and a pump beam in a spun fiber and in a randomly birefringent fiber, the latter being relevant to optical telecommunication systems. On the basis of a geometrical analysis of the Hamiltonian singularities of the system, we provide a complete understanding of the phenomenon of polarization attraction in these two systems, which allows to achieve a control of the polarization state of the signal beam by adjusting the polarization of the pump. In spun fibers, all polarization states of the signal beam are attracted toward a specific line of polarization states on the Poincaré sphere, whose characteristics are determined by the polarization state of the injected backward pump.

Bilateral negative sentinel nodes accurately predict absence of lymph node metastasis in early cervical cancer: results of the SENTICOL study.

Purpose: Sentinel lymph node (SLN) biopsy may be used to target lymph node metastases in patients with early cervical cancer. Whether SLN biopsy only is acceptable in the staging and surgical management of early cervical cancer remains unknown. This prospective multicenter study (SENTICOL [Ganglion Sentinelle dans le Cancer du Col]) assessed the sensitivity and negative predictive value (NPV) of SLN biopsy.