Mechanical and Industrial Engineering, Department of

Learning Retention of Thoracic Pedicle Screw Placement Using a High-Resolution Augmented Reality Simulator With Haptic Feedback

Thu, 01 Sep 2011 05:00:00 GMT

Learning Retention of Thoracic Pedicle Screw Placement Using a High-Resolution Augmented Reality Simulator With Haptic Feedback Luciano, Cristian J; Banerjee, P Pat; Bellotte, Brad; Oh, G Michael; Lemole, Michael; Charbel, Fady T.; Roitberg, Ben Background. In this study we evaluated the use of a part-task simulator with 3D and haptic feedback as a training tool for a common neurosurgical procedure – placement of thoracic pedicle screws. Objective. The purpose of this study was to evaluate the learning retention of thoracic pedicle screw placement on a high-performance augmented reality and haptic technology workstation. Methods. Fifty one fellows and residents performed thoracic pedicle screw placement on the simulator. The virtual screws were drilled into a virtual patient’s thoracic spine derived from a computed tomography data set of a real patient. Results: With a 12.5% failure rate, a two-proportion z-test yielded P= 0.08. For performance accuracy, an aggregate Euclidean distance deviation from entry landmark on the pedicle and a similar deviation from the target landmark in the vertebral body yielded P=0.04 from a two sample t-test in which the rejected null hypothesis assumes no improvement in performance accuracy from the practice to the test sessions, and the alternative hypothesis assumes an improvement. Conclusions. The performance accuracy on the simulator was comparable to the accuracy reported in literature on recent retrospective evaluation of such placements. The failure rates indicated a minor drop from practice to test sessions, and also indicated a trend (P=0.08) towards learning retention resulting in improvement from practice to test sessions. The performance accuracy showed a 15% mean score improvement and over 50% reduction in standard deviation from practice to test. It showed evidence (P=0.04) of performance accuracy improvement from practice to test session. Post print version of article may differ from published version. The definitive version is available through Lippincott, Williams & Wilkins at DOI: 10.1227/NEU.0b013e31821954ed Luciano, C. J., Banerjee, P. P., Bellotte, B., Lemole, G. M., Jr., Oh, M., Charbel, F. T., & Roitberg, B. 2011. Learning retention of thoracic pedicle screw placement using a high-resolution augmented reality simulator with haptic feedback. Neurosurgery.2011 Sep;69(1 Suppl Operative):ons14-9;

Nano-Encapsulated Smart Tunable Phase Change Materials

Mon, 01 Aug 2011 05:00:00 GMT

Nano-Encapsulated Smart Tunable Phase Change Materials Sinha-Ray, S.; Sahu, R.P.; Yarin, A.L. We achieve the intercalation of different types of paraffins and their mixtures with triglycerides inside carbon nanotubes (CNTs) by means of self-sustained diffusion followed by a proper rinsing. The CNTs were investigated using TEM, which showed that they were intercalated inside and clean outside. For the mixtures melting can be realized in an interval of about 20 0C, which opens new opportunities for Phase Change Materials (PCM) attracting attention in relation to solar energy storage, cooling of power electronic devices and the energy-saving technologies. This is a copy of an article published in the journal Soft Matter © 2011 Royal Society of Chemistry. DOI: 10.1039/c1sm05973d

Superoleophobic and conductive carbon nanofiber/fluoropolymer composite films

Thu, 01 Mar 2012 06:00:00 GMT

Superoleophobic and conductive carbon nanofiber/fluoropolymer composite films Das, Arindam; Schutzius, Thomas M.; Bayer, Ilker S.; Megaridis, Constantine M. A solution-based, large-area coating procedure is developed to produce conductive polymer composite films consisting of hollow-core carbon nanofibers (CNFs) and a fluoroacrylic copolymer available as a water-based dispersion. CNFs (100 nm dia., length similar to 130 mu m) were dispersed by sonication in a formic acid/acetone co-solvent system, which enabled colloidal stability and direct blending of the CNFs and aqueous fluoroacrylic dispersions in the absence of surfactants. The dispersions were sprayed on smooth and microtextured surfaces, thus forming conformal coatings after drying. Nanostructured composite films of different degrees of oil and water repellency were fabricated by varying the concentration of CNFs. The effect of substrate texture and CNF content on oil/water repellency was studied. Water and oil static contact angles (CAs) ranged from 98 degrees to 164 degrees and from 61 degrees to 164 degrees, respectively. Some coatings with the highest water/oil CAs displayed self-cleaning behavior (droplet roll-off angles <10 degrees). Inherent conductivity of the composite films ranged from 63 to 940 S/m at CNF concentrations from 10 to 60 wt.%, respectively. Replacement of the long CNFs with shorter solid-core carbon nanowhiskers (150 nm dia., length 6-8 mu m) produced stable fluoropolymer-nanowhisker dispersions, which were ink-jetted to generate hydrophobic, conductive, printed line patterns with a feature size similar to 100 mu m. (C) 2011 Elsevier Ltd. All rights reserved. NOTICE: this is the author’s version of a work that was accepted for publication in Carbon. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Carbon, [Vol 50, Issue 3, March 2012] DOI: 10.1016/j.carbon.2011.11.006

Fuel and diluent property effects during wet compression of a fuel aerosol under RCM conditions

Thu, 01 Mar 2012 06:00:00 GMT

Fuel and diluent property effects during wet compression of a fuel aerosol under RCM conditions Goldsborough, S.S.; Johnson, M.V.; Zhu, G.S.; Aggarwal, S.K. Wet compression of fuel aerosols has been proposed as a means of creating gas-phase mixtures of involatile diesel-representative fuels and oxidizer + diluent gases for rapid compression machine (RCM) experiments. The intent of this study is to investigate the effects of fuel and diluent gas properties on the wet compression process, specifically to: (a) explore a range of fuels which could have applicability in aerosol RCM experiments, and (b) fundamentally understand how fuel and diluent gas properties affect the wet compression process and assess which ones are most important. Insight gained from this work can be utilized to aid the design and successful operation of aerosol RCMs. A spherically-symmetric, single-droplet wet compression model is used where n-Heptane, n-dodecane, 2,2,4,4,6,8,8- heptamethylnonane (isocetane), n-hexadecane (cetane) and n-eicosane are investigated as the dieselrepresentative fuels, while comparisons are made to water droplets. Nitrogen, neon and argon are selected as the gas-phase diluents while the oxidizer is considered to be oxygen at atmospheric concentrations. Initial droplet diameters of d0 = 3 and 8μm are used based on results of previous studies where the overall compression time is set to 15.3ms with the maximum volumetric compression ratio 13.4. An overall equivalence ratio of ϕ = 1.0 is used. It is shown that under these conditions, involatile fuels up to ~ n-hexadecane appear to be candidates for aerosol RCM experiments. However, the use of small droplets (d0 < 5μm) will be necessary in order to ensure complete vaporization and adequate gas-phase mixing in advance of low temperature chemical reactivity. Fuels with higher boiling points might not be useable unless extremely small droplets (d0 < 1μm) and low pressures (e.g., P0 < 0.5bar) are employed along with longer compression times. In addition, the boiling curve (i.e., saturation pressure) and Lf are found to be the dominant fuel properties while the density-weighted mass diffusivity, ρgDg, which controls the rate of gas phase mass diffusion, and thus compositional stratification, generally plays a secondary role. The heat capacity and molar mass are the dominant diluent properties that affect the near-droplet and ‘far-field’ conditions. The gas-phase mixture Lewis number (Leg) contributes to either greater compositional (Leg>1) or thermal (Leg<1) stratification. For large hydrocarbons and oxygenated hydrocarbons that are representative of diesel fuels Leg ~ 3-5, and therefore compositional stratification could be significant; this characteristic has the potential to complicate interpretation of ignition/oxidation data acquired from these machines. NOTICE: this is the author’s version of a work that was accepted for publication in Fuel. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Fuel, Vol 93, Issue 1, (MAR 2012) DOI: 10.1016/j.fuel.2011.06.027