Vertebral fracture assessment:Current research status and application in patients with kyphoplasty

Imaging of the spine is of paramount importance for the recognition of osteoporotic vertebral fractures(VFs), and standard radiography(SR) of the spine is the suggested diagnostic method but is not routinely used because of the cost and radiation exposure considerations. VF assessment(VFA) is an efficient, low radiation method for identifying VFs at the time of bone mineral density(BMD) measurement. Prediction models used to indicate the need for VFA may have little predictive power in subspecialty referral populations such as rheumatologic patients or patients who underwent kyphoplasty. Rheumatologic patients are frequently at increased risk for VFs, and VFA should be performed on an individual basis, also taking in account the guidelines for the general population. Kyphoplasty is a new minimal invasive procedure for the treatment of VFs and is being performed with increasing frequency. Following kyphoplasty, there may be a risk of new VFs in adjacent vertebrae. The assessment and follow-up of patients who underwent kyphoplasty requires repetitive X-ray imaging with the known limitations of SR. Thus, VFA may facilitate the evaluation of VFs in these patients because most of the kyphoplasty patients would fulfill the criteria. In a pilot study, we measured the BMD and performed VFA in 28 patients treated with kyphoplasty. Ratios of anterior to posterior(A/P) and middle to posterior(M/P) height were measured, and Genant's method was used to classify vertebrae accordingly. Intraobserver and interobserver reliability for A/P, M/P and the Genant's method were determined. Only 1 patient did not meet the criteria for VFA. Of the 364 available vertebrae, 295 could be analyzed. Most missing data(concerning 69 vertebrae) occurred in the upper thoracic region. Three of the 69 non-eligible vertebrae were lumbar vertebrae with cement leakage from the kyphoplasty procedure. In our hands, VFA was highly reproducible, demonstrating very good agreement in terms of intraobserver and interobserver reliability. Agreement was very good onthe vertebral level, "vertebrae with kyphoplasty" level and "2 above and 1 below the kyphoplasty vertebrae"level. The application of Genant's method to these patients also resulted in perfect agreement. We believe that the potential value of VFA in patients treated with kyphoplasty requires further evaluation, particularly comparing VFA with SR and performing a longitudinal follow-up. More research will help to adopt care processes that determine which patients require VFA and how often VFA should be performed, while also considering the impact of this technique on the cost of healthcare organizations.

Characterization of InGaN Solar Cells

The III-V materials are extensively studied for optoelectronic applications in the blue and UV spectral regions. InGaN ternary alloy is considered for its wide spectral coverage, good electrical characteristics and appreciable resistance to high electrical currents. For this purpose, the operation of InGaN photovoltaic cells was studied by 2D numerical simulation under AM1.5 spectrum illumination, using the software Silvaco and the two environments Athena/Atlas.

Comparative study of abrasion via microindentation and microscratch tests of reinforced and unreinforced lamellar cast iron

This study compares micro-abrasive wear in two kinds of grey cast iron. Classical lamellar cast iron with fully pearlitic matrix(FGL1) and lamellar micro-alloyed cast iron with phosphorus and boron(FGL2) are used. FGL2 has a fully pearlitic matrix reinforced by the hard phosphorus eutectic phase. The microstructures of these two types of iron are mechanically characterized using nanoindentation tests. Vickers microindentation and microscratch tests are also performed on these iron samples. The indent and scratch images obtained via scanning electron microscopy were used to compare the scratch damage to the two kinds of iron. The friction coefficient is discussed in terms of applied load, indenter attack angle, and scratch damage. Nanoindentation tests show an improvement in graphite’s mechanical properties and an increase in the matrix hardness of the FGL2, relatively to FGL1. The same damage forms for both microindentation and microscratch testing were observed for the two iron samples. However, cracking of the hard phase is observed in FGL2. The results show that the scratching of the micro-alloyed iron(FGL2) leads to less matrix damage and to an extended microploughing wear mechanism. However, at low normal load, the reinforcement of the matrix can increase the friction coefficient.

A CFD modeling of oil-water flow in pipeline: Interaction analysis and identification of boundary separation

The aim of this study is to simulate the flow of emulsion (immiscible liquids) which is a complex phenomenon in the petroleum industry. In this study, three types of emulsions (O/W) were simulated usingby CFD which has been applied to predict the interaction behavior of oil with water for differentemulsions (25%Oe75%W, 50%Oe50%W and 75%Oe25%W). Numerical modeling illustrated that the obtained results of the velocity profiles were very good agreement with the experimental data for threetype of emulsions. In addition, the analytical model of interaction analysis and identification of boundaryseparation for two-phase flow approve with the experimental data available, despite the emulsionsremain to be more difficulty due to the complex chemical reactions. The results of this study can providethe best solutions for corrosion during hydrocarbons transportation. Thus, CFD approach is recommended to use for numerical investigates due to the high accuracy.