RESUMEN
Objective: The aim of our study was to investigate the role of three-dimensional arterial spin labeling (3D-ASL) perfusion in the diagnosis and follow-up of children with viral encephalitis. Methods: Twenty-five consecutive children with viral encephalitis and 25 healthy children of similar age were recruited for the study between 2017 and 2020. Conventional magnetic resonance imaging and 3D-ASL were performed for all subjects, and a color map of cerebral blood flow (CBF) was generated. The images were classified into three groups depending on the time points at which the magnetic resonance examinations were conducted, including the initial admission scan, inpatient review, and follow-up review. Clinical, neuroradiologic, and follow-up features were studied.The CBF values of the lesion area in the diseased brain group and the bilateral temporal cortex in the control group were measured and the differences between the two groups were compared. Results: Perfusion was significantly increased in the acute cerebral disease group, and CBF and normalized cerebral blood flow(nCBF) were significantly higher than in the control group (124.5 vs 70.3 mL/100 g/min, 2.85 vs 1.36). Follow-up revealed that brain tissue perfusion in the lesion area of nine children decreased gradually after treatment, as their condition improved. Conclusion: Brain tissue perfusion in children with viral encephalitis increases during the acute stage and decreases when the condition improves. 3D-ASL provides a reference for diagnosis and follow-up of viral encephalitis in children.
RESUMEN
We successfully prepared butyl rubber (IIR)/polypropylene (PP) thermoplastic vulcanizate (IIR/PP-TPV) for shock-absorption devices by dynamic vulcanization (DV) using octyl-phenolic resin as a vulcanizing agent and studied the morphological evolution and properties during DV. We found that the damping temperature region of the IIR/PP-TPV broadened with the disappearance of the glass transition temperature (Tg) in the PP phase, which is ascribed to the improvement of compatibility between the IIR and PP with increasing DV time. As DV progresses, the size of the dispersed IIR particles and the PP crystalline phase decreases, leading to the formation of a sea-island morphology. After four cycles of recycling, the retention rates of tensile strength and elongation at break of the IIR/PP-TPV reached 88% and 86%, respectively. The size of the IIR cross-linking particles in the IIR/PP-TPV becomes larger after melt recombination, and the continuous PP phase provides excellent recyclability. Significantly, the prepared IIR/PP-TPV exhibits excellent recyclability, high elasticity, and good damping property.
