ABSTRACT
Achieving selective C-H bond cleavage is critical for developing catalytic processes that transform small alkanes to value-added products. The present study clarifies the molecular-level origin for an exceptionally strong preference for propane to dissociate on the crystalline PdO(101) surface via primary C-H bond cleavage. Using reflection absorption infrared spectroscopy (RAIRS) and density functional theory (DFT) calculations, we show that adsorbed propane σ-complexes preferentially adopt geometries on PdO(101) in which only primary C-H bonds datively interact with the surface Pd atoms at low propane coverages and are thus activated under typical catalytic reaction conditions. We show that a propane molecule achieves maximum stability on PdO(101) by adopting a bidentate geometry in which a H-Pd dative bond forms at each CH3 group. These results demonstrate that structural registry between the molecule and surface can strongly influence the selectivity of a metal oxide surface in activating alkane C-H bonds.
ABSTRACT
Surgical advances using the retrohepatic caval preservation technique in liver transplantation (LT) has significantly decreased the need for veno-venous bypass (VVB). However, VVB still remains a viable adjunct of LT. The venous return cannula has traditionally been inserted using a cut-down technique via the axillary vein, but this technique carries significant risks for lymphorrhea, infection, or nerve damage. Since 2001, our institution has routinely used VVB in adult LT surgery. Percutaneous insertion of an internal jugular venous return cannula is performed by the attending anesthesiologist. The aim of this report is to describe the method of insertion and management of a percutaneous veno-venous return cannula in the internal jugular vein during LT. In-depth detail as well as video clips will provide a reference for LT centers wishing to apply this method in their practice.