Analysis of micromixers and biocidal coatings on water-treatment membranes to minimize biofouling.

Biofouling, the unwanted growth of biofilms on a surface, of water-treatment membranes negatively impacts in desalination and water treatment. With biofouling there is a decrease in permeate production, degradation of permeate water quality, and an increase in energy expenditure due to increased cross-flow pressure needed. To date, a universal successful and cost-effect method for controlling biofouling has not been implemented. The overall goal of the work described in this report was to use high-performance computing to direct polymer, material, and biological research to create the next generation of water-treatment membranes. Both physical (micromixers - UV-curable epoxy traces printed on the surface of a water-treatment membrane that promote chaotic mixing) and chemical (quaternary ammonium groups) modifications of the membranes for the purpose of increasing resistance to biofouling were evaluated. Creation of low-cost, efficient water-treatment membranes helps assure the availability of fresh water for human use, a growing need in both the U. S. and the world

Spinal dural arteriovenous fistula formation after scoliosis surgery: case report

Spinal dural arteriovenous fistulas are diagnostically challenging lesions, and they are not well described in patients with a history of a spinal deformity correction. The authors present the challenging case of a 74-year-old woman who had previously undergone correction of a spinal deformity with subsequent revision. Several years after the last deformity operation, she developed a progressive myelopathy with urinary incontinence over a 6-month period. After evaluation at the authors\u27 institution, an angiogram was obtained, demonstrating a fistula at the T12-L1 region. Surgical ligation of the fistula was performed with subsequent improvement of the neurological symptoms. This case is thought to represent the first fistula documented in an area of the spine that had previously been operated on, and to the authors\u27 knowledge, it is the first case report to be associated with spinal deformity surgery. A brief historical overview and review of the pathophysiology of spinal dural arteriovenous fistulas is also included

Repair of Thoracic Spinal Cord Herniation: 2-Dimensional Operative Video

Spinal cord herniation is an uncommon surgically treatable cause of thoracic myelopathy and progressive paraplegia. The thoracic spinal cord focally protrudes through a defect in the dura, resulting in progressive weakness, numbness, and spasticity affecting the lower extremities, in addition to possible urinary symptoms. In this video, we present the case of a 69-yr-old female who presented with 3 yr of progressive thoracic myelopathy due to a thoracic spinal cord herniation at T4-T5. We demonstrate the surgical steps to lyse arachnoid webs, mobilize the spinal cord, reduce the spinal cord herniation, and repair the dural defect. Appropriate patient consent was obtained

A comparison of ventricular volume and linear indices in predicting shunt dependence in aneurysmal subarachnoid hemorrhage

Background: Guidelines for determining shunt dependence after aneurysmal subarachnoid hemorrhage (aSAH) remain unclear. We previously demonstrated change in ventricular volume (VV) between head CT scans taken pre- and post-EVD clamping was predictive of shunt dependence in aSAH. We sought to compare the predictive value of this measure to more commonly used linear indices. Methods: We retrospectively analyzed images of 68 patients treated for aSAH who required EVD placement and underwent one EVD weaning trial, 34 of whom underwent shunt placement. We utilized an in-house MATLAB program to analyze VV and supratentorial VV (sVV) in head CT scans obtained before and after EVD clamping. Evans' index (EI), frontal and occipital horn ratio (FOHR), Huckman's measurement, minimum lateral ventricular width (LV-Min.), and lateral ventricle body span (LV-Body) were measured using digital calipers in PACS. Receiver operating curves (ROC) were generated. Results: Area under the ROC curves (AUC) for the change in VV, sVV, EI, FOHR, Huckman's, LV-Min., and LV-Body with clamping were 0.84, 0.84, 0.65, 0.71.0.69, 0.67, and 0.66, respectively. AUC for post-clamp scan measurements were 0.75, 0.75, 0.74, 0.72, 0.72, 0.70, and 0.75, respectively. Conclusion: VV change with EVD clamping was more predictive of shunt dependence in aSAH than change in linear measurements with clamping and all post-clamp measurements. Measurement of ventricular size on serial imaging with volumetrics or linear indices utilizing multidimensional data points may therefore be a more robust metric than unidimensional linear indices in predicting shunt dependence in this cohort. Prospective studies are needed for validation

Lumbar Lateral Recess Decompression: 2-Dimensional Operative Video

Lateral recess stenosis is a common cause of lumbar radiculopathy in adults. A lumbar nerve root travels in the lateral recess prior to exiting the spinal canal via the neural foramen. In the lateral recess, the traversing nerve root is susceptible to compression by the degenerative hypertrophy of the medial facet in addition to hypertrophied ligamentum flavum and herniated intervertebral disc.1 These degenerative changes are also typically associated with neural foraminal stenosis. Surgical treatment in unilateral cases consists of hemilaminectomy, medial facetectomy, foraminotomy, and, if applicable, microdiscectomy. In this video, we present a case of a 64-yr-old male presenting with progressive left L5 radiculopathy refractory to conservative management, with magnetic resonance imaging (MRI) findings of left L4-5 foraminal and lateral recess stenosis. We demonstrate the operative steps to complete a left L4-5 hemilaminectomy, medial facetectomy, foraminotomy, and microdiscectomy. Appropriate patient consent was obtained

CFD Simulation and Performance Analysis of Alternative Designs for High-Temperature Solid Particle Receivers

Direct-absorption solid particle receivers are theoretically capable of yielding temperatures in excess of 1000°C, which enables higher efficiency power cycles and lower thermal storage costs. This paper presents rigorous CFD simulations of alternative solid particle receiver designs with recirculation to help identify optimal configurations that maximize the receiver thermal efficiency. The alternative receiver designs considered are a north-facing cavity receiver and a face-down surround-field cavity receiver. The CFD simulations model incident solar radiation from a heliostat field as a boundary condition on the model domain. The CFD simulations also couple convective flow with the thermal and discrete-phase (particle) solutions, which in turn affects absorption of incident solar radiation and thermal re-radiation within the receiver. The receivers are optimized to yield comparable particle temperatures at the outlets of 750-850°C, heated from an injection temperature of 300°C, and are compared on the basis of thermal efficiency. The CFD simulations yielded thermal efficiencies of the north-facing receiver at 72.3% (losses were 6.5% radiative and 20.9% convective) and the face-down receiver at 78.9% (losses were 11.4% radiative and 9.6% convective) at solar noon on March 22. Ongoing efforts are focused on reducing convective and radiative losses from both receiver configurations