Effects of cement addition and briquetting of rock wool on its geomechanical stability in landfills.

Landfilling of mineral wool waste in big bags at separate landfill compartments is required in Austria. This results in enormous differences in the Young's moduli between common construction and demolition (C&D) waste compartments and mineral wool compartments, which causes severe accidents in terms of overturned vehicles due to sudden subsidence of the subsurface. Conditioning of mineral wool waste might be applied to adjust its geomechanical behaviour to that of common C&D waste but has never been investigated scientifically before. In this study we compare three scenarios for the conditioning of rock wool for landfilling: (A) loosely packing, (B) cutting comminution + cement addition and (C) cutting comminution + cement-supported briquetting. The performance of the different sample bodies under landfill conditions was simulated at the lab scale by cyclic loading (1223-3112 N, up to 160 cycles) using a 'Wille Geotechnik UL 300' press. The deformation was monitored during the experiment and Young's modulus was derived graphically, whereas the test execution was piston controlled. The Young's modulus increased during the experiments from 0.2 MPa to 4.6 MPa for scenario (A), from 0.6 MPa to 20.5 MPa for scenario (B) and from 7.5 MPa to 111.0 MPa for scenario (C). These results show that a combination of comminution and cement-supported briquetting significantly increases the geotechnical performance of mineral wool waste with respect to landfilling, which is still three orders of magnitude below that of common C&D waste, which is in the range of 30,000 MPa.

Fiber-optic Monitoring of Spinal Cord Hemodynamics in Experimental Aortic Occlusion.

BACKGROUND: Spinal cord ischemia occurs frequently during thoracic aneurysm repair. Current methods based on electrophysiology techniques to detect ischemia are indirect, non-specific, and temporally slow. In this article, the authors report the testing of a spinal cord blood flow and oxygenation monitor, based on diffuse correlation and optical spectroscopies, during aortic occlusion in a sheep model. METHODS: Testing was carried out in 16 Dorset sheep. Sensitivity in detecting spinal cord blood flow and oxygenation changes during aortic occlusion, pharmacologically induced hypotension and hypertension, and physiologically induced hypoxia/hypercarbia was assessed. Accuracy of the diffuse correlation spectroscopy measurements was determined via comparison with microsphere blood flow measurements. Precision was assessed through repeated measurements in response to pharmacologic interventions. RESULTS: The fiber-optic probe can be placed percutaneously and is capable of continuously measuring spinal cord blood flow and oxygenation preoperatively, intraoperatively, and postoperatively. The device is sensitive to spinal cord blood flow and oxygenation changes associated with aortic occlusion, immediately detecting a decrease in blood flow (-65 ± 32%; n = 32) and blood oxygenation (-17 ± 13%, n = 11) in 100% of trials. Comparison of spinal cord blood flow measurements by the device with microsphere measurements led to a correlation of R = 0.49, P < 0.01, and the within-sheep coefficient of variation was 9.69%. Finally, diffuse correlation spectroscopy is temporally more sensitive to ischemic interventions than motor-evoked potentials. CONCLUSION: The first-generation spinal fiber-optic monitoring device offers a novel and potentially important step forward in the monitoring of spinal cord ischemia.

Dataset of fire tests with lithium-ion battery electric vehicles in road tunnels.

A set of five fire tests involving battery electric vehicles and conventional cars was performed in a tunnel. This data article provides the dataset of some of the determined parameters: air temperature, air velocity and heat release rate. The air temperature was measured at several locations and at different heights, distributed in the cross section of the tunnel. The velocity of the incoming air was also measured. The third parameter, the heat release rate (HRR), was calculated based on the enthalpy flow before and after the fire location. This parameter is important for characterizing the size of a vehicle fire. The data provide a reference for the evaluation of BEV fires and could be taken as reference for further fire studies. They might be also of interest to research groups dealing with simulation applications, like three-dimensional CFD simulations.

Cerebellar infarction requiring surgical decompression in patient with COVID 19 pathological analysis and brief review.

BACKGROUND: This report and literature review describes a case of a COVID-19 patient who suffered a cerebellar stroke requiring neurosurgical decompression. This is the first reported case of a sub-occipital craniectomy with brain biopsy in a COVID-19 patient showing leptomeningeal venous intimal inflammation. CLINICAL DESCRIPTION: The patient is a 48-year-old SARS-COV-2 positive male with multiple comorbidities, who presented with fevers and respiratory symptoms, and imaging consistent with multifocal pneumonia. On day 5 of admission, the patient had sudden change in mental status, increased C-Reactive Protein, ferritin and elevated Interleukin-6 levels. Head CT showed cerebral infarction from vertebral artery occlusion. Given subsequent rapid neurologic decline from cerebellar swelling and mass effect on his brainstem emergent neurosurgical intervention was performed. Brain biopsy found a vein with small organizing thrombus adjacent to focally proliferative intima with focal intimal neutrophils. CONCLUSION: A young man with COVID-19 and suspected immune dysregulation, complicated by a large cerebrovascular ischemic stroke secondary to vertebral artery thrombosis requiring emergent neurosurgical intervention for decompression with improved neurological outcomes. Brain biopsy was suggestive of inflammation from thrombosed vessel, and neutrophilic infiltration of cerebellar tissue.

Laser safety in fiber-optic monitoring of spinal cord hemodynamics: a preclinical evaluation.

The prevention and treatment of spinal cord injury are focused upon the maintenance of spinal cord blood flow, yet no technology exists to monitor spinal cord ischemia. We recently demonstrated continuous monitoring of spinal cord ischemia with diffuse correlation and optical spectroscopies using an optical probe. Prior to clinical translation of this technology, it is critically important to demonstrate the safety profile of spinal cord exposure to the required light. To our knowledge, this is the first report of in situ safety testing of such a monitor. We expose the spinal cord to laser light utilizing a custom fiber-optic epidural probe in a survival surgery model (11 adult Dorset sheep). We compare the tissue illumination from our instrument with the American National Standards Institute maximum permissible exposures. We experimentally evaluate neurological and pathological outcomes of the irradiated sheep associated with prolonged exposure to the laser source and evaluate heating in ex vivo spinal cord samples. Spinal cord tissue was exposed to light levels at ∼18 × the maximum permissible exposure for the eye and ∼ ( 1 / 3 ) × for the skin. Multidisciplinary testing revealed no functional neurological sequelae, histopathologic evidence of laser-related injury to the spinal cord, or significant temperature changes in ex vivo samples. Low tissue irradiance and the lack of neurological, pathological, and temperature changes upon prolonged exposure to the laser source offer evidence that spinal cord tissues can be monitored safely with near-infrared optical probes placed within the epidural space.

Neurosurgery in East Africa: Innovations.

In the last 10 years, considerable work has been done to promote and improve neurosurgical care in East Africa with the development of national training programs, expansion of hospitals and creation of new institutions, and the foundation of epidemiologic and cost-effectiveness research. Many of the results have been accomplished through collaboration with partners from abroad. This article is the third in a series of articles that seek to provide readers with an understanding of the development of neurosurgery in East Africa (Foundations), the challenges that arise in providing neurosurgical care in developing countries (Challenges), and an overview of traditional and novel approaches to overcoming these challenges to improve healthcare in the region (Innovations). In this article, we describe the ongoing programs active in East Africa and their current priorities, and we outline lessons learned and what is required to create self-sustained neurosurgical service.

Optical monitoring and detection of spinal cord ischemia.

Spinal cord ischemia can lead to paralysis or paraparesis, but if detected early it may be amenable to treatment. Current methods use evoked potentials for detection of spinal cord ischemia, a decades old technology whose warning signs are indirect and significantly delayed from the onset of ischemia. Here we introduce and demonstrate a prototype fiber optic device that directly measures spinal cord blood flow and oxygenation. This technical advance in neurological monitoring promises a new standard of care for detection of spinal cord ischemia and the opportunity for early intervention. We demonstrate the probe in an adult Dorset sheep model. Both open and percutaneous approaches were evaluated during pharmacologic, physiological, and mechanical interventions designed to induce variations in spinal cord blood flow and oxygenation. The induced variations were rapidly and reproducibly detected, demonstrating direct measurement of spinal cord ischemia in real-time. In the future, this form of hemodynamic spinal cord diagnosis could significantly improve monitoring and management in a broad range of patients, including those undergoing thoracic and abdominal aortic revascularization, spine stabilization procedures for scoliosis and trauma, spinal cord tumor resection, and those requiring management of spinal cord injury in intensive care settings.

Biomechanical comparison of instrumented and uninstrumented multilevel cervical discectomy versus corpectomy.

STUDY DESIGN: In vitro flexibility test comparing biomechanics of cervical corpectomy versus discectomy with and without instrumentation. OBJECTIVES: To evaluate whether the additional effort required to perform multilevel discectomies instead of corpectomies is worthwhile biomechanically. SUMMARY OF BACKGROUND DATA: Both cervical corpectomy and discectomy have been shown to be effective clinically. No previous biomechanical comparison exists. METHODS: Fourteen human cadaveric cervical spines were studied: 1) intact, 2) after discectomy and wedge grafting at C4-C5, C5-C6, and C6-C7 (Group 1) or corpectomy and strut grafting of C5 and C6 (Group 2), 3) after attaching a locking metal plate from C4-C7, and 4) after adding posterior locking lateral mass screw/rod instrumentation across C4-C7. Non-constraining, nondestructive torques induced flexion, extension, lateral bending, and axial rotation (maximum, 1.5 Nm) while angular motion was measured stereophotogrammetrically. RESULTS: Discectomy and grafting did not alter the range of motion (ROM) significantly from normal during any loading mode (P > 0.11). Corpectomy and grafting allowed a significantly greater range of motion than normal during flexion, lateral bending, and axial rotation (P < 0.05). Addition of an anterior plate reduced ROM to significantly less than normal during all loading modes in both groups (P < 0.005). Addition of posterior instrumentation further reduced ROM significantly in both groups (P < 0.01). There was no significant difference in ROM between corpectomy and discectomy groups in any loading mode whether uninstrumented (P > 0.18), anteriorly plated (P > 0.33), or anteriorly and posteriorly instrumented (P > 0.30). CONCLUSIONS: Less difference in stability was observed than was predicted between specimens receiving multilevel discectomy versus multilevel corpectomy, regardless of whether specimens were left unplated, plated anteriorly, or fixated with combined anterior/posterior instrumentation.

Orthogonal interlocking tandem clipping technique for the reconstruction of complex middle cerebral artery aneurysms.

OBJECTIVE: Complex aneurysms arising at the middle cerebral artery (MCA) bifurcation frequently present a microsurgical challenge to effectively obliterate while maintaining patency of the distal MCA branches. These aneurysms are often multilobed, with their long axis aligned with the long axis of the M1 trunk, placing the dome of the aneurysm in the surgeons' line of sight, preventing an unobstructed view of the entire bifurcation and proximal M1 segment. MCA aneurysms often have a broad neck, splaying the bifurcation. An orthogonal interlocking tandem clipping technique, maximizing the use of fenestrated aneurysm clips, is presented as a means to completely obliterate the aneurysm and simultaneously "reconstruct" the MCA bifurcation. CLINICAL PRESENTATIONS AND INTERVENTION: Fifteen complex MCA aneurysms were treated using an interlocking tandem clipping technique. In its simplest application, the blades of the initial aneurysm clip are incorporated into the fenestration of the second clip. Obliteration of the residual aneurysm is achieved with the blades of the second, fenestrated clip. RESULTS: Satisfactory aneurysm obliteration and reconstruction of the MCA bifurcation was achieved in all cases using this technique, with excellent neurological outcomes. CONCLUSION: Morphologically complex multilobed MCA aneurysms can be effectively clipped with "reconstruction" of the normal vascular anatomy using a tandem interlocking clipping technique. A fenestrated clip is used to incorporate the blades of the initial clip, while obliterating the remainder of the aneurysm.