High-Temperature XAS Study of Fe2SiO4 Liquid: Reduced Coordination of Ferrous Iron.

X-ray absorption spectroscopy (XAS) of Fe(2+) in Fe(2)SiO(4) liquid at 1575 kelvin and 10(-4) gigapascal (1 bar) shows that the Fe(2+) -O bond length is 1.98 +/- 0.02 angstroms compared with approximately 2.22 angstroms in crystalline Fe(2)SiO(4) (fayalite) at the melting point (1478 kelvin), which indicates a decrease in average Fe(2+) coordination number from six in fayalite to four in the liquid. Anharmonicity in the liquid was accounted for using a data analysis procedure. This reduction in coordination number is similar to that observed on the melting of certain ionic salts. These results are used to develop a model of the medium-range structural environment of Fe(2+) in olivine-composition melts, which helps explain some of the properties of Fe(2)SiO(4) liquid, including density, viscosity, and the partitioning of iron and nickel between silicate melts and crystalline olivines. Some of the implications of this model for silicate melts in the Earth's crust and mantle are discussed.

[Closure of sternotomy with Cotrel staplers]. / Fermeture des sternotomies à l'aide des agrafes de Cotrel.

The authors describe a new method for the closure of median sternotomies based on immediate compression with two or three Cotrel-Dubousset (CD) staples. This method was effective in a series of 100 patients. It was the curative treatment of septic sternal pseudarthrosis, and has been extended to high risk patients (age, severe sternal osteoporosis, obesity, diabetes, chronic respiratory insufficiency) or when surgery requires resection of the internal mammary arteries (IMA).

[Value of intramedullary locked nailing in distal fractures of the tibia]. / Intérêts de l'enclouage centromédullaire verrouillé dans les fractures distales de jambe.

PURPOSE OF THE STUDY: This study is a retrospective analysis of 38 extra-articular distal tibial fractures treated by intramedullary locked nailing. PATIENTS AND METHODS: 38 patients with a distal metaphyseal extra-articular fracture (43 A AO type) or with minimal ankle joint extension were managed. There was 26 men and 12 women with a mean age of 32.3 years, 10 fractures were open. The fractures were transverse or oblique in 13 cases, with torsional or flexion wedge in 12 cases and spiroïd in 13 cases. In only 2 cases was the fibula intact. AO classification was not useful because many fractures began more proximally than the limit described by Müller. All the fractures were fixed by closed locked intramedullary nailing : the nail was cut just after the distal hole and impacted close to the subchondral plate. In 7 cases the fibula was fixed too. RESULTS: There was no postoperative complication in 27 cases. Three patients had a transient nerve palsy (one tibial nerve and two common fibular nerve). In ten cases the nail was dynamized. One patient had a non union but healed with a new dynamic nail. Two patients had a delayed union and healed after dynamization and osteotomy of the fibula. The mean time to union was 5 months (2 to 8). 8 patients had a varus or a valgus deformity of 3 to 6 degrees. 11 patients suffered from anterior knee pain and in 5 patients the fracture site was painful. In 18 patients a CT scan was performed : 6 had a rotational deformity from 4 to 26 degrees, and 2 a tibial lengthening (discrepancy of 7 and 9 mm). CONCLUSION: Closed intramedullary nailing is a safe and effective method for the treatment of distal metaphyseal tibial fractures. The authors propose a new classification.

Contribution to the study of the tributaries and the termination of the external jugular vein.

The dissection of 100 external jugular veins in 50 cadavers was the object of this anatomic study. A certain number of notions concerning the afferent veins, the mode of termination and the valvular system of this vessel were defined. 1) Afferent veins. Along its pathway toward the deep venous system, the external jugular vein successively received: the transverse cervical vein in 88 cases (88%), usually opposite the intersection of the external jugular vein with the dorsal border of the sterno- cleidomastoid muscle; the suprascapular vein in 47 cases (47%); the anterior jugular vein in 46 cases (46%); the cervical vein or anastomosis with the latter in 13 cases (13%). 2) Mode of termination. Forty-three subjects presented a symmetric mechanism. 100 anastomoses can be classed into three types: in 60 cases (60%), the external jugular vein flowed into the jugulo-subclavian venous confluence; in 36 cases (36%), in to the subclavian vein at a distance from its junction with the internal jugular vein; in 4 cases (4%) in to the trunk of the internal jugular vein. 3) Study of the valves. There were studied in 25 subjects (50 external jugular veins). The valves were found in the ostial and paraostial position in 49 out of 50 veins.