Spinal involvement in mucopolysaccharidosis IVA (Morquio-Brailsford or Morquio A syndrome): presentation, diagnosis and management.

Mucopolysaccharidosis IVA (MPS IVA), also known as Morquio-Brailsford or Morquio A syndrome, is a lysosomal storage disorder caused by a deficiency of the enzyme N-acetyl-galactosamine-6-sulphate sulphatase (GALNS). MPS IVA is multisystemic but manifests primarily as a progressive skeletal dysplasia. Spinal involvement is a major cause of morbidity and mortality in MPS IVA. Early diagnosis and timely treatment of problems involving the spine are critical in preventing or arresting neurological deterioration and loss of function. This review details the spinal manifestations of MPS IVA and describes the tools used to diagnose and monitor spinal involvement. The relative utility of radiography, computed tomography (CT) and magnetic resonance imaging (MRI) for the evaluation of cervical spine instability, stenosis, and cord compression is discussed. Surgical interventions, anaesthetic considerations, and the use of neurophysiological monitoring during procedures performed under general anaesthesia are reviewed. Recommendations for regular radiological imaging and neurologic assessments are presented, and the need for a more standardized approach for evaluating and managing spinal involvement in MPS IVA is addressed

Effect of surgical experience and spine subspecialty on the reliability of the {AO} Spine Upper Cervical Injury Classification System

OBJECTIVE The objective of this paper was to determine the interobserver reliability and intraobserver reproducibility of the AO Spine Upper Cervical Injury Classification System based on surgeon experience (< 5 years, 5–10 years, 10–20 years, and > 20 years) and surgical subspecialty (orthopedic spine surgery, neurosurgery, and "other" surgery). METHODS A total of 11,601 assessments of upper cervical spine injuries were evaluated based on the AO Spine Upper Cervical Injury Classification System. Reliability and reproducibility scores were obtained twice, with a 3-week time interval. Descriptive statistics were utilized to examine the percentage of accurately classified injuries, and Pearson’s chi-square or Fisher’s exact test was used to screen for potentially relevant differences between study participants. Kappa coefficients (κ) determined the interobserver reliability and intraobserver reproducibility. RESULTS The intraobserver reproducibility was substantial for surgeon experience level (< 5 years: 0.74 vs 5–10 years: 0.69 vs 10–20 years: 0.69 vs > 20 years: 0.70) and surgical subspecialty (orthopedic spine: 0.71 vs neurosurgery: 0.69 vs other: 0.68). Furthermore, the interobserver reliability was substantial for all surgical experience groups on assessment 1 (< 5 years: 0.67 vs 5–10 years: 0.62 vs 10–20 years: 0.61 vs > 20 years: 0.62), and only surgeons with > 20 years of experience did not have substantial reliability on assessment 2 (< 5 years: 0.62 vs 5–10 years: 0.61 vs 10–20 years: 0.61 vs > 20 years: 0.59). Orthopedic spine surgeons and neurosurgeons had substantial intraobserver reproducibility on both assessment 1 (0.64 vs 0.63) and assessment 2 (0.62 vs 0.63), while other surgeons had moderate reliability on assessment 1 (0.43) and fair reliability on assessment 2 (0.36). CONCLUSIONS The international reliability and reproducibility scores for the AO Spine Upper Cervical Injury Classification System demonstrated substantial intraobserver reproducibility and interobserver reliability regardless of surgical experience and spine subspecialty. These results support the global application of this classification system

Engineering Solution in Monitoring Nanoparticle-Fluid Flow During Nanocomposites Processing

New generation composites using nanoparticle-filled matrices have been significantly broadened to encompass a large variety of one-, two-, and three-dimensional systems made of distinctly dissimilar components mixed at the nanometer scale. Nevertheless, during the fabrication process of these novel composites, many problems potentially could arise. One such problem is the clogging of the channels of the microfiber matrix used due to strong interactions between the nanoparticle additives and the matrix walls. In this paper, a two-dimensional simulation model based on Lagrangian multiphase approach for nanoparticle-filled fluid, which flows around an aligned microfiber matrix, is introduced to investigate and predict the nanoparticles trajectories and their interactions with fluid flow and microfiber walls. An energy “imbalance” technique has been applied between the fluid and the microfiber walls to prevent any potential sticking of the nanoparticle additives on the microfiber walls. The trajectory of the nanoparticle has been predicted by integrating the force balance on it in a Lagrangian reference frame. The governing integral equations for the conservation of mass, momentum and energy have been solved in a segregated numerical fashion by a Control-Volume-Based Finite-Element Method

Carbon Nanofluids Flow Behavior in Novel Composites

Nanocomposite materials have broadened significantly to encompass a large variety of systems, made of distinctly dissimilar components and mixed at the nanometer scale. This rapidly expanding field is generating many exciting new advanced composites with promising properties. However, during the fabrication of nanocomposites, many problems could arise and remain as challenging tasks. One such problem is controlling of the nanofluid flow behavior around the microfiber perform as in case of Resin Transfer Molding (RTM) process because of the high resin viscosity and the low preform permeability. In this paper, a two-dimensional simulation model based on the Eulerian multiphase approach has been performed and solved to investigate and predict the flow characteristics of a carbon nanofluid around a staggered microfiber matrix. ‘The interactions between the microfiber walls and the interfacial nanofluid layers during the flow process have been also studied. Based on the predicted results an energy “imbalance” technique has been applied between the microfiber walls and the interfacial nanofluid layers allowing them the potential to flow more smoothly around the microfiber walls to prevent any potential sticking on the microfiber walls

Carbon Nanoparticle-Filled Polymer Flow in the Fabrication of Novel Fiber Composites

During the fabrication process of advanced composites using nanoparticle-filled matrices, many problems potentially could arise. One such problem is the clogging of the channels of the microfiber matrix used due to strong interactions between the nanoparticle additives and the matrix walls. In the present paper, a two-dimensional simulation model based on an Eulerian multiphase flow approach is introduced to investigate and predict the flow characteristics of carbon nanoparticle-filled fluid around carbon microfiber matrix. The interactions between the microfiber matrix walls and the nanoparticle additives have been studied, and an energy “imbalance” technique has been applied between the fluid and the microfiber walls to prevent any potential sticking of the nanoparticle additives on the microfiber matrix walls during the flow process. The concept of phasic volume fractions is utilized, and the effects of external body forces, lift forces, and virtual mass forces are introduced into the momentum equations. The phase coupled SIMPLE algorithm is employed to solve the model

Effect of Carbon Nanofiber Additives on Thermal Behavior of Phase Change Materials

Thermal performance of nanocomposite carbon nanofibers filled paraffin wax was studied experimentally and analytically. The transient temperature response of made nanocomposite was measured during its solidification process and the cooling rate was predicted. It was found that nanocomposite thermal conductivities were enhanced significantly causing the cooling rate to increase. An analytical model was introduced based on one-dimensional heat conduction approach to predict the effective thermal conductivity for the new nanocomposites and its findings showed good agreement with the experimental data. Also, a comparative study was performed to investigate the effect of carbon nanofibers surface characteristics on thermal performance of paraffin wax

Bubble Growth Mechanism in Carbon Foams

The present work is a numerical study to predict the growth mechanism of a non-spherical bubble assisted for a carbon foam fabrication process. An approach for two dimensional non-spherical mass-diffusion controlled bubble growth in an isothermal Newtonian liquid of infinite extent is considered. Using the two dimensional unsteady form of the equations governing the conservation of mass and momentum, bubble growth is solved as a function of time using a fixed-grid sharp interface finite volume method. A comparative study is performed by considering previous cases of study and shows good agreement, which reflects the validity of the present model. A parametric study highlighting the effects of the non-spherical growth of the bubble is performed in order to emphasize how controlled bubble growth can be achieved. In each case a change in a particular parameter resulted in a distinct change of the bubble shape

Merits of Employing Foam Encapsulated Phase Change Materials for Pulsed Power Electronics Cooling Applications

In the present work, the potential of using foam structures impregnated with phase change materials (PCMs) as heat sinks for cooling of electronic devices has been numerically studied. Different design parameters have been investigated such as foam properties (porosity, pore size, and thermal conductivity), heat sink shape, orientation, and use of internal fins inside the foam-PCM composite. Due to huge difference in thermal properties between the PCM and the solid matrix, two energy equation model has been adopted to solve the energy conservation equations. This model can handle local thermal nonequilibrium condition between the PCM and the solid matrix. The numerical model is based on volume averaging technique, and the finite volume method is used to discretize the heat diffusion equation. The findings show that, for steady heat generation, the shape and orientation of the composite heat sink have significant impact on the system performance. Conversely, in the case of power spike input, use of a PCM with low melting point and high latent heat is more efficient

Graphite Foams Infiltrated with Phase Change Materials as Alternative Materials for Space and Terrestrial Thermal Energy Storage Applications

In this work, a numerical study is proposed to investigate and predict the thermal performance of graphite foams infiltrated with phase change materials, PCMs, for space and terrestrial energy storage systems. The numerical model is based on a volume averaging technique while a finite volume method has been used to discretize the heat diffusion equation. A line-by-line solver based on tri-diagonal matrix algorithm has been used to iteratively solve the algebraic discretization equations. Because of the high thermal conductivity of graphite foams, the PCM-foam system thermal performance has been improved significantly. For space applications, the average value of the output power of the new energy storage system has been increased by more than eight times. While for terrestrial applications, the average output power using carbon foam of porosity 97% is about five times greater than that for using pure PCM

Numerical and Experimental Investigations of Melting and Solidification Processes of High Melting Point PCM in a Cylindrical Enclosure

In the present work, a computational model is developed to investigate and predict the thermal performance of high melting point phase change material during its melting and solidification processes within a cylindrical enclosure. In this model the phases are assumed to be homogeneous and a source term, S, arises from melting or solidification process is considered as a function of the latent heat of fusion and the liquid phase fraction. The numerical model is verified with a test problem and an experiment is performed to assess the validity of the assumptions of it and an agreement between experimental and computational results is achieved. The findings show that utilizing of PCMs of high melting points is a promising technique especially in space applications