Carbene Addition Isomers of C70 formed in the Flame of Low-Pressure Combustion.

In the flames during low-pressure combustion, not only a rich variety of fullerenes but also many reactive intermediates can be produced (e.g., carbene, CH2) that are short-lived and cannot be stabilized directly under normal circumstances. These intermediates can be captured by fullerene carbon cages for stabilization. In this paper, three C71H2 isomers were synthesized in situ in low-pressure benzene-acetylene-oxygen diffusion flame combustion. The results, which were unambiguously characterized by single-crystal X-ray diffraction, show that the three isomers are carbene addition products of D5h-C70 on different sites. The relative energies and stability of different C71H2 isomers are revealed by Ultraviolet-Visible (UV-Vis) absorption spectroscopy, in combination with theoretical calculations, in this work. Both the in situ capture and theoretical study of these C71H2 isomers in low-pressure combustion will provide more information regarding carbene additions to other fullerenes or other carbon clusters at high temperatures.

Lateral epicondyle osteotomy approach vs. olecranon osteotomy approach: an anatomic study of cadavers.

BACKGROUND: Exposure of the articular surface is the key to successful open reduction and internal fixation treatment for coronal shear fractures of the distal humerus. The olecranon osteotomy approach has previously been described as one of the most effective exposure approaches. Nevertheless, this approach cannot expose the anterior trochlea, and it is impossible to reduce and fix the capitellum under direct vision. The purpose of this study was to compare the exposure of the articular surface of the distal humerus between the lateral epicondyle osteotomy approach (group L) and the olecranon osteotomy approach (group O). METHODS: Each approach was performed on 8 freshly frozen upper limbs of adult cadavers. After each approach was completed, a 0.5-mm Kirschner wire is inserted along the edge to mark the visible part of the articular surface. Then, the soft tissue of each elbow is removed, and a surface-scanning system is used to create a digital 3-dimensional model. The visible part of the articular surface obtained by each surgical approach was mapped and quantified using markers created by Kirschner wires. RESULTS: The lateral epicondyle osteotomy approach and the olecranon osteotomy approach exposed 0.8 ± 0.0 and 0.6 ± 0.0 of the distal humeral articular surface (P < .001), 1.0 ± 0.0 and 0.3 ± 0.1 of the capitellum (P < .001), 0.6 ± 0.0 and 0.7 ± 0.0 of the trochlea (P < .001), 0.7 ± 0.0 and 0.5 ± 0.1 of the anterior trochlea (P < .001), and 0.5 ± 0.0 and 1.0 ± 0.0 of the posterior trochlea, respectively (P < .001). CONCLUSION: Compared with the olecranon osteotomy approach, the lateral epicondyle osteotomy approach could more fully expose the total articular surface of the distal humerus, capitellum, and anterior trochlea, but the olecranon osteotomy approach could more fully expose the trochlea and posterior trochlea.