Determination of the metal ordering in meteoritic (Fe,Ni)3P crystals.

Synchrotron radiation diffraction studies of meteoritic (Fe,Ni)3P crystals have been performed to reveal the ordering of the elements Fe and Ni on the three metal sites M1, M2 and M3 of the unit cell. The delta synthesis technique, which is a two-wavelength method using anomalous dispersion effects, was applied. For (Fe,Ni) phosphide crystals with different Fe:Ni ratios extracted from different meteorites, it was found that Ni occupies the M3 site and also partially the M2 site, avoiding the M1 position, whereas the M1 site is preferentially occupied by Fe. In connection with earlier results known from the literature, this metal distribution seems to be characteristic of this compound, and is independent of thermodynamic formation conditions.

Reversal of paraparesis after thoracic aneurysm repair by cerebrospinal fluid drainage.

PURPOSE: To describe a case of reversal of delayed paraparesis, after an elective type I thoracoabdominal aortic aneurysm (TAAA) repair, via cerebrospinal fluid (CSF) drainage. CLINICAL FEATURES: A 75-yr-old woman developed paraparesis 13 hr after type I TAAA repair. The patient had been given combined regional and general anesthesia. There was no cerebrospinal fluid drain inserted at the time of surgery. The patient was hemodynamically stable throughout the procedure and was transported to the intensive care unit with trachea intubated and lungs ventilated. She demonstrated some initial lower limb paraparesis but had good recovery of limb function three hours after cessation of the epidural infusion. However, five hours and forty-five minutes after stopping the epidural, she was again paraparetic. Peripheral nerve injury, prolonged effects of epidural local anesthetic, and epidural hematoma were ruled out as precipitating factors. Cord ischemia was considered possible and a CSF catheter was inserted. Immediate improvement was seen upon catheter insertion and commencement of drainage, beginning with movement in the left toes and foot. Drainage was performed when the CFS pressure became > 15 mmHg. Motor function in the lower limbs continued to improve with each drainage extending to complete recovery after 40 hr. She was discharged home 11 days after surgery with no neurological deficit. CONCLUSION: Drainage of CSF was useful in treating a case of post-TAAA neurologic deficit.

Impact process: an important geological phenomenon.

The impact process was for a long period of time, even after a wider acceptance among the geological community, considered to be a marginal phenomenon in the Earth sciences. The first decade or two have showed an importance of the process itself and consequent events only too clearly. The present paper is a review describing the history and development of the impact hypothesis, structure and origin of impact craters, influence of huge impacts on the living environment and other aspects of the impact process from the point of view of geology s.l.

Ancrod (Arvin) as an alternative to heparin anticoagulation for cardiopulmonary bypass.

Heparin is the anticoagulant used during cardiopulmonary bypass (CPB). Both the use of heparin and the reversal of its effect with protamine have well-documented complications. Ancrod is a defibrinogenating enzyme that has been used as an anticoagulant in humans, but its use as an anticoagulant for CPB has been limited to studies in animals. Twenty patients for elective aortocoronary bypass surgery were anticoagulated by means of an intravenous infusion of ancrod pre-operatively. Target plasma fibrinogen concentrations of 0.40-0.80 g/l were achieved within 13.3 +/- 2.5 h using an average dose of ancrod of 1.65 +/- 0.55 U/g. All perfusions were without incident. Postoperative blood loss (2286 +/- 1311 cc) was compared to that of 20 matched controls (1737 +/- 973 cc), as was blood product use; 4.1 +/- 2.1 U of packed cells versus 2.5 +/- 2.3 U (P less than 0.05) and 5.6 +/- 3.1 U of plasma versus 2.6 +/- 2.9 U (P less than 0.05) in the ancrod and heparin-treated groups, respectively. There were no differences in the postoperative courses or recovery periods of the ancrod-treated and control patients. This study confirms the efficacy and feasibility of ancrod as an alternative form of anticoagulation for CPB.