Isomerization of Silylallene

The isomerization of silylallene to seven of its isomers has been studied using ab initio molecular orbital theory. The energetics were obtained using quadratically convergent configuration interaction (QCISD(T)) with the 6-311G(d,p) basis set, at geometries optimized by second-order perturbation theory (MP2) with the 6-31G(d) basis set. Test calculations using multiconfiguration wave functions show that the configurational mixing is small; therefore, the single-configuration-based methods are reliable. In comparison to the isomerization of the parent allene, the silyl group was found to migrate more easily than the hydrogen. In particular, the 1,3-migration that converts silylallene to silylpropyne has barriers of 55.8 and 52.9 kcal mol-1 for the forward and backward reactions, respectively. These are roughly half of the 1,3-hydrogen migration barrier in allene

β-Silicon Effect on Singlet Carbene Stability

Calculations using double ζ plus polarization basis sets or effective core potentials and two configuration MCSCF wave functions augmented by multireference singles and doubles configuration interaction are used to investigate the effect of various Substituents on the singlet triplet splitting in methylene. Of particular interest is the conclusion that when CH2SiH3 or CH2GeH3 is a substituent, the cumulative effect of the polarizability of the C-Si and C-Ge bonds and the rotation of these bonds into the appropriate alignment required for effective electron donation into the carbene π orbital results in preferential stabilization of the corresponding singlet carbenes, a β-silicon (or germanium) effect analogous to that which is well-known in cation chemistry

Reconsideration of a structural model of a casein micelle for small-angle X-ray scattering measurements

departmental bulletin pape

Optimal Temperature of Graft Preservation after ex Vivo Gene Transfer in Lung Isografts

The aim of this study was to determine the optimal temperature of graft preservation after ex vivo gene transfer to rat lung isografts. Left lungs were harvested and infused with cationic lipid/LacZ-DNA complex via the pulmonary artery, and the grafts were stored for 4h. The grafts (n＝7) were allocated into groups IﾝIV according to the storage temperature:4℃, 10℃, 16℃, and 23℃, respectively. Forty-eight h after orthotopic transplantation, the arterial blood gas was analyzed and the peak airway pressure (PAP) and the level of LacZ protein production in the grafts were measured by reverse transcription polymerase chain reaction. After reperfusion, the grafts were stained with hematoxylin and eosin. The grafts in groups III and IV showed more deterioration as evidenced by decreased arterial oxygen tension, increased PAP, and predominant infiltration of inflammatory cells compared with groups I and II. The level of LacZ production was significantly lower in group I than in groups IIﾝIV. The optimal temperature of lung graft preservation after ex vivo gene transfer was determined to be 10℃, balancing considerations of lung injury and efficiency of transgene expression.</p