Experimental evidence of phase transition of silica polymorphs in basaltic eucrites: implications for thermal history of protoplanetary crust.

Silica polymorphs occur under various pressures and temperature conditions, and their characteristics can be used to better understand the complex metamorphic history of planetary materials. Here, we conducted isothermal heating experiments of silica polymorphs in basaltic eucrites to assess their formation and stability. We revealed that each silica polymorph exhibits different metamorphic responses: (1) Quartz recrystallizes into cristobalite when heated at ≥ 1040 °C.

Hydrogen transfer reactions via organic radicals in gamma-irradiated chibaite.

Chibaite, a silica-framework structure with cage-like voids occupied by gaseous molecules, was found in marine sediments. Its formation age could be evaluated using electron spin resonance (ESR) if the radicals formed by natural radiation can be assumed to accumulate over time. To investigate whether hydrogen transfer reactions, where organic radicals withdraw hydrogen atoms from other molecules in adjacent cages, occur in chibaite and affect ESR dating, gamma-irradiated chibaite was measured by ESR.

Reversible and multiphasic parenchymal changes in MRI after coil embolization for a ruptured cerebral aneurysm.

Background: Reversible and multiphasic parenchymal changes in magnetic resonance imaging (MRI) are exceedingly rare. The authors experienced a case of reversible and multiphasic parenchymal changes in MRI after coil embolization for a ruptured cerebral aneurysm.

Case Description: A 48-year-old woman had a sudden onset of severe headaches and was referred to us for coil embolization.

[Usefulness of CT in the Lateral Decubitus Position for Preoperative Evaluation of Cranioplasty].

Patients with massive brain swelling undergo external decompressive craniectomy to manage intracranial pressure. Following supratentorial craniectomy, and after the brain swelling is relieved, cranioplasty is performed. Although feasibility of the surgery is usually assessed by CT scanning in a supine position, it is sometimes difficult to determine whether the surgery can be performed safely.

Multiple Cerebral Hemorrhagic Lesions Depicted by Susceptibility-Weighted Imaging in a Patient with Down Syndrome: Case Report.

Our objective is to study a 53-year-old woman with Down syndrome presented with massive lobar hematoma in the left fronto-parietal lobe, and who underwent craniotomy and hematoma evacuation. Histopathological diagnosis of surgical specimen was amyloid angiopathy. Postoperative magnetic resonance studies were performed.