Core-shell excitation of isoxazole at the C, N, and O K-edges - an experimental NEXAFS and theoretical TD-DFT study.

The near-edge X-ray absorption fine structure (NEXAFS) spectra of the gas-phase isoxazole molecule have been measured by collecting total ion yields at the C, N, and O K-edges. The spectral structures have been interpreted using time-dependent density functional theory (TD-DFT) with the short-range corrected SRC2-BLYP exchange-correlation functional. Experimental and calculated energies of core excitations are generally in good agreement, and the nature of observed core-excitation transitions has been elucidated. The experimental C 1s, N 1s, and O 1s core electron binding energies (CEBEs) have additionally been estimated from another yield measurement where the neutral fragments in high-Rydberg (HR) states were ionized by the electric field. For comparison, theoretical CEBEs have been calculated at the ΔM06-2X//mixed basis set level. We have also calculated the vibrationally resolved spectra pertaining to the lowest C 1s and N 1s core-excited roots in the Franck-Condon-Herzberg-Teller (FCHT) approximation. These spectra correlate well with the observed spectral features and have proven useful in resolving certain ambiguities in the assignment of the low-lying C 1s NEXAFS bands.

Frontier orbital stability of nitroxyl organic radicals probed by means of inner shell resonantly enhanced valence band photoelectron spectroscopy.

We have investigated the frontier orbitals of persistent organic radicals known as nitroxyls by resonant photoelectron spectroscopy (ResPES) under inner shell excitation. By means of this site-specific technique, we were able to disentangle the different atomic contributions to the outer valence molecular orbitals and examine several core-hole relaxation pathways involving the singly occupied molecular orbital (SOMO) localized on the nitroxyl group. To interpret the ResPES intensity trends, especially the strong enhancement of the SOMO ionized state at the N K-edge, we computed the Dyson spin orbitals (DSOs) pertaining to the transitions between the core-excited initial states and several of the singly ionized valence final states. We found that the computed vertical valence ionization potentials and norms of the DSOs are reasonably reliable when based on the long-range corrected CAM-B3LYP density functional. Thanks to their unpaired electrons, nitroxyls have recently found application in technological fields implying a spin control, such as spintronics and quantum computing. The present findings on the electronic structure of nitroxyl persistent radicals furnish important hints for their implementation in technological devices and, more in general, for the synthesis of new and stable organic radicals with tailored properties.

A surprisingly complex aqueous chemistry of the simplest amino acid. A pulse radiolysis and theoretical study on H/D kinetic isotope effects in the reaction of glycine anions with hydroxyl radicals.

A pulse radiolysis study was carried out of the reaction rate constants and kinetic isotope effects of hydroxyl-radical-induced H/D abstraction from the most-simple alpha-amino acid glycine in its anionic form in water. The rate constants and yields of three predominantly formed radical products, glycyl (NH2-*CH-CO2-), aminomethyl (NH2-*CH2), and aminyl (*NH-CH2-CO2-) radicals, as well as of their partially or fully deuterated analogs, were found to be of comparable magnitude. The primary, secondary, and primary/secondary H/D kinetic isotope effects on the rate constants were determined with respect to each of the three radicals. The unusual variety of products for such an elementary reaction between two small and simple species indicates a complex mechanism with several reactions taking place simultaneously. Thus, a theoretical modeling of the reaction mechanism and kinetics in the gas- and aqueous phase was performed by using the unrestricted density functional theory with the BB1K functional (employing the polarizable continuum model for the aqueous phase), unrestricted coupled cluster UCCSD(T) method, and improved canonical variational theory. Several hydrogen-bonded prereaction complexes and transition states were detected. In particular, the calculations pointed to a significant mechanistic role of the three-electron two-orbital (sigma/sigma* N therefore O) hemibonded prereaction complexes in the aqueous phase. A good agreement with the experimental rate constants and kinetic isotope effects was achieved by downshifting the calculated reaction barriers by 3 kcal mol(-1) and damping the NH(D) stretching frequency by a factor of 0.86.

Inferior angle of the scapula as a vascularized bone graft: an anatomic study.

In reconstructing patients with massive midface losses, the authors required a vascularized bone graft that could be used to reconstruct the palate and orbital floor, provide vertical maxillary support, and provide soft tissue. The inferior angle of the scapula appears to be a promising source of vascularized bone stock, and until now, there has been no clear description of its vascular anatomy. The purpose of this study was to define the vascular anatomy of the inferior angle of the scapula. Thirteen fresh cadavers were studied. The subscapular artery was injected with Microfil (Flow Tec, Carver, MA) at its origin. Two branches of the subscapular artery were found to converge on the angle of the scapula: the descending osseous branch of the circumflex scapular, and the transverse branch of the thoracodorsal. The descending osseous branch of the circumflex scapular artery supplied the inferior angle of the scapula in 100 percent of cases. The transverse branch of the thoracodorsal artery supplied it in 76 percent of cases. The descending osseous branch of the circumflex scapular artery is the principal artery supplying the inferior angle of the scapula.