Refractory status epilepticus after inadvertent intrathecal injection of tranexamic acid treated by magnesium sulfate.

We present a case of accidental injection of tranexamic acid during spinal anesthesia for an elective cesarean delivery. Immediately following intrathecal injection of 2mL of solution, the patient complained of severe back pain, followed by muscle spasm and tetany. As there was no evidence of spinal block, the medications given were checked and a 'used' ampoule of tranexamic acid was found on the spinal tray. General anesthesia was induced but muscle spasm and tetany persisted despite administration of a non-depolarizing muscle relaxant. Hemodynamic instability, ventricular tachycardia, and status epilepticus developed, which were refractory to phenytoin, diazepam, and infusions of thiopental, midazolam and amiodarone. Magnesium sulfate was administered postoperatively in the intensive care unit, following which the frequency of seizures decreased, eventually stopping. Unfortunately, on postoperative day three the patient died from cardiopulmonary arrest after an oxygen supply failure that was not associated with the initial event. This report underlines the importance of double-checking medications before injection in order to avoid a drug error. As well, it suggests that magnesium sulfate may be useful in stopping seizures caused by the intrathecal injection of tranexamic acid.

New mechanism for the alpha to omega martensitic transformation in pure titanium.

We propose a new direct mechanism for the pressure driven alpha-->omega martensitic transformation in pure titanium. A systematic algorithm enumerates all possible pathways whose energy barriers are evaluated. A new, homogeneous pathway emerges with a barrier at least 4 times lower than other pathways. The pathway is shown to be favorable in any nucleation model.

Nucleation in systems with elastic forces.

Systems with long-range interactions when quenched into a metastable state near the pseudospinodal exhibit nucleation processes that differ from classical nucleation seen near the coexistence curve. In systems with long-range elastic forces the description of the nucleation process can be quite subtle due to the presence of bulk and surface elastic compatibility constraints. We analyze the nucleation process in a simple 2D model with elastic forces and show that the nucleation process generates critical droplets with a different structure than the stable phase. This has implications for nucleation in many crystal-crystal transitions, specifically martensites and shape memory alloys, and for the structure of the final state.

Raman spectroscopic analysis of mo/si multilayers.

Raman spectra are reported from MoSi2 polycrystalline powder and soft x-ray Mo/Si multilayers. The sharp lines at 323 and 438 cm-1 are all due to crystalline MoSi2. These lines in the powder sample intensify with annealing. The Raman spectra of as-deposited multilayers shows a broad asymmetric peak, highest at about 480 cm-1. We attribute this to α-Si which is highly disordered. In contrast to α-Si in semiconductor/semiconductor and semiconductor/dielectric multilayers, in the Mo/Si samples the Raman signal can vanish after modest heating. This provides evidence that the composition of the silicon component of the multilayer changes even with 200°C annealing. Further annealing also produces the signature for crystalline MoSi2 in the multilayer samples. This is the first report of the characterization of Mo/Si soft x-ray multilayers by Raman spectroscopy, and it indicates that Raman spectroscopy may be an effective technique for characterizing these soft x-ray multilayers and may be useful in studying their interfaces.