The current research presents a novel and sustainable load-bearing system utilizing cellular lightweight concrete block masonry walls. These blocks, known for their eco-friendly properties and increasing popularity in the construction industry, have been studied extensively for their physical and mechanical characteristics. However, this study aims to expand upon previous research by examining the seismic performance of these walls in a seismically active region, where cellular lightweight concrete block usage is emerging. The study includes the construction and testing of multiple masonry prisms, wallets, and full-scale walls using a quasi-static reverse cyclic loading protocol. The behavior of the walls is analyzed and compared in terms of various parameters such as force–deformation curve, energy dissipation, stiffness degradation, deformation ductility factor, response modification factor, and seismic performance levels, as well as rocking, in-plane sliding, and out-of-plane movement. The results indicate that the use of confining elements significantly improves the lateral load capacity, elastic stiffness, and displacement ductility factor of the confined masonry wall in comparison to an unreinforced masonry wall by 102%, 66.67%, and 5.3%, respectively. Overall, the study concludes that the inclusion of confining elements enhances the seismic performance of the confined masonry wall under lateral loading.
INTRODUCTION: Cortical spreading depolarization (CSD) represents a pathomechanistic target for neuroprotective therapy given the association with lesion development and poor outcomes following traumatic brain injury (TBI).METHODS: Experiments were conducted using 9-week-old Sprague Dawley rats. Daily neurobehavioral scores were recorded by trained, blinded observers. Using an established weight-drop model, animals received either single moderate (modTBI; n = 23) or four daily mild (rmTBI; n = 30) head impacts. Sham animals received brief anesthetic without TBI (n = 40). Animals underwent cranial window surgery and CSDs were electrically triggered by cortical stimulation; electrophysiological, imaging and blood-flow were monitored using intravital microscopy. Ketamine (100uM topical and 25 mg/kg IP, respectively) and memantine (10 mg/kg IP) were tested in vivo. Subsequently, a RCT was conducted (N=31) using memantine (10 mg/kg) or saline (2.5 cc/kg). Primary outcome: proportion of animals resilient to rmTBI (neurobehavioral scores ≥ 6 out of 12).RESULTS: In modTBI, and rmTBI animal models, intraperitoneal ketamine and memantine reduced the proportion of electrically triggered CSDs by 79-88%, and 42-73%, respectively. The average relative amplitude of change in ECoG were reduced by 70-75%, and 51-60%, respectively. Memantine significantly reduced spreading depression and cortical hypoperfusion following CSD. RCT animals in the memantine group were more likely resilient to injury (93% vs. 56%; p = 0.023) and had higher mean neurological scores (9.27 (SD 3.08) vs. 5.56 (SD 3.05)), p < 0.001) compared to saline.CONCLUSIONS: The NMDA-receptor antagonist memantine supresses CSDs and reduces pathological cerebral hypoperfusion in vivo following CSDs. In a rmTBI RCT, memantine prevented neurological decline.
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