A feasible and automatic free tool for T1 and ECV mapping

Purpose: Cardiac magnetic resonance (CMR) is a useful non-invasive tool for characterizing tissues and detecting myocardial fibrosis and edema. Estimation of extracellular volume fraction (ECV) using T1 sequences is emerging as an accurate biomarker in cardiac diseases associated with diffuse fibrosis. In this study, automatic software for T1 and ECV map generation consisting of an executable file was developed and validated using phantom and human data. Methods: T1 mapping was performed in phantoms and 30 subjects (22 patients and 8 healthy subjects) on a 1.5T MR scanner using the modified Look-Locker inversion-recovery (MOLLI) sequence prototype before and 15 min after contrast agent administration. T1 maps were generated using a Fast Nonlinear Least Squares algorithm. Myocardial ECV maps were generated using both pre- and post-contrast T1 image registration and automatic extraction of blood relaxation rates. Results: Using our software, pre- and post-contrast T1 maps were obtained in phantoms and healthy subjects resulting in a robust and reliable quantification as compared to reference software. Coregistration of pre- and post-contrast images improved the quality of ECV maps. Mean ECV value in healthy subjects was 24.5% ± 2.5%. Conclusions: This study demonstrated that it is possible to obtain accurate T1 maps and informative ECV maps using our software. Pixel-wise ECV maps obtained with this automatic software made it possible to visualize and evaluate the extent and severity of ECV alterations

Traditional as radical

An essay that considers the traditional methodologies of making as a model for contemporary sustainable design

Characteristics of Keratoconus Patients at a Tertiary Eye Center in India

Purpose: To evaluate the presentation and characteristics of patients with keratoconus at a tertiary eye care center in Mumbai, India. Methods: This single center, non-comparative, retrospective cohort analysis was performed on patients with keratoconus who presented to the Clear Vision Eye Center clinic from April 2007 to March 2009. Data was collected to characterize correlations among visual acuity, corneal biomicroscopic findings, and refractive and topographic findings in keratoconus. Results: Records of 274 patients including 189 male and 85 female subjects with mean age of 20.1±3.5 (range, 13 to 29) years at the time of diagnosis were assessed. There was history of skin allergy in 73 (26.6%), symptomatic ocular allergy in 67 (24.45%) and asthma in 31 (11.31%) patients. The most frequent corneal sign was Fleischer′s ring which was observed in 81% of cases. Corneal topography revealed mean simK (simulated keratometry) of 53.3±6.1 (range, 41.2 to 69.0) diopters. Corneal topography analysis with the Cone Location Magnitude Index disclosed the presence of inferior cones in 93% of patients. Conclusion: This group of patients had younger age at presentation and more severe keratoconus as compared to western populations; contact lenses were used only in a minority of patients

Active heat exchange system development for latent heat thermal energy storage

Active heat exchange concepts for use with thermal energy storage systems in the temperature range of 250 C to 350 C, using the heat of fusion of molten salts for storing thermal energy are described. Salt mixtures that freeze and melt in appropriate ranges are identified and are evaluated for physico-chemical, economic, corrosive and safety characteristics. Eight active heat exchange concepts for heat transfer during solidification are conceived and conceptually designed for use with selected storage media. The concepts are analyzed for their scalability, maintenance, safety, technological development and costs. A model for estimating and scaling storage system costs is developed and is used for economic evaluation of salt mixtures and heat exchange concepts for a large scale application. The importance of comparing salts and heat exchange concepts on a total system cost basis, rather than the component cost basis alone, is pointed out. The heat exchange concepts were sized and compared for 6.5 MPa/281 C steam conditions and a 1000 MW(t) heat rate for six hours. A cost sensitivity analysis for other design conditions is also carried out

Resolving X-Ray Photoelectron Spectra of Ionic Liquids with Difference Spectroscopy

X-ray photoelectron spectroscopy (XPS) is a powerful element-specific technique to determine the composition and chemical state of all elements in an involatile sample. However, for elements such as carbon, the wide variety of chemical states produce complex spectra that are difficult to interpret, consequently concealing important information due to the uncertainty in signal identity. Here we report a process whereby chemical modification of carbon structures with electron withdrawing groups can reveal this information, providing accurate, highly refined fitting models far more complex than previously possible. This method is demonstrated with functionalised ionic liquids bearing chlorine or trifluoromethane groups that shift electron density from targeted locations. By comparing the C 1s spectra of non-functional ionic liquids to their functional analogues, a series of difference spectra can be produced to identify exact binding energies of carbon photoemissions, which can be used to improve the C 1s peak fitting of both samples. Importantly, ionic liquids possess ideal chemical and physical properties, which enhance this methodology to enable significant progress in XPS peak fitting and data interpretation

High efficient material and process combination for future aircraft applications based on advanced sheet molding compound technologies

The increasing need for efficient passenger aircraft led to the development of innovative lightweight designs and an increasing demand on new lightweight materials such as carbon fiber reinforced plastics (CFRP) in the recent decades. Due to the high weight specific mechanical properties and the relatively high cost of raw materials, semi-finished and manufacturing the use of CFRP is limited on high performance applications, especially for components of the primary structures of aircraft. Subsequently, fiber reinforced plastics (FRP) are also used in cabin and interior. Due to lower mechanical loads, but high requirements on fire protection, optics, surface and acoustics sandwich structures are used in most cases. Generally, these sandwich structures are made of honey comb cores and top layers based on glass fiber fabrics impregnated by phenolic resin. However, higher complexity of the parts, directly integrated functions and the required surface properties for applying the decorative films or paintings can only be realized by a lot of manufacturing, finishing and assembly steps. In order to meet the increasing demands for lightweight structures for cabin and cargo applications the aerospace industry is working on improvements and developments of new materials, manufacturing processes and construction methods for secondary structures. One auspicious technology is the combination of Sheet Molding Compounds (SMC) with long fiber reinforcements and directed, pre-impregnated continuous fiber reinforcements, which are processed in a single-stage pressing and curing process to produce a new kind of hybrid composite components for aircraft. This hybrid composite technology is characterized by the realization of geometrically complex, highly functional and lightweight components with low process cycle times in the range of 30 to 180 seconds. Depending on the specific requirements and the application thermoset matrix systems based on unsaturated polyester, vinyl ester or epoxy resins can be used. The ability of full automation and the relatively high material usage in the range of 90 percent and higher make this technology economically efficient. In addition, the process obtains the possibility to integrate various functions directly. Coloring and the direct integration of metallic components such as inserts or nuts are only some examples for that. Time and costs for rework assembly and further process steps can be reduced due to the extended possibilities of functional integration and the higher complexity of the components. In addition, an optimized utilization of material and the possibility of using recycled carbon fibers from a pyrolysis process or dry chopped fibers from production waste obtain an increase of resource and energy efficiency. The carbon fibers may be reused as long-fiber reinforcements for veils. Due to the described potentials there are a lot of auspicious applications of this hybrid composite material for future aircraft cabins. Load carrying cabin monuments, highly functional storage systems for hand luggage, complex fittings, holders or brackets are only some exemplary applications. By the integration of continuous fiber reinforcements following the load paths of the appropriate component high lightweight potentials and also structural applications can be realized. However, the high requirements on fire, smoke and toxicity (FST) and the required lightweight specifications of cabin and cargo structures create huge challenges for the material and the process development. This publication deals with the development of the combination of SMC and pre-impregnated, tailored carbon fiber reinforcements for cabin and cargo applications in aerospace industry. The main focusses are different investigations on the material properties and analyses of the manufacturing procedures of advanced SMC formulations based on unsaturated polyester resin with a high proportion of the inorganic flame retardant additives as well as aluminum trihydrate (ATH). Generally, a high degree of fire resistance additives has negative effects on the fiber-resin adhesion, the impregnation of the fibers and the flow behavior during the compression molding. Nevertheless, the findings on this hybrid composite technology obtain promising possibilities for functional integrations, lightweight constructions and the cost-efficient production of secondary structure aircraft components

Composite Crew Module (CCM) Permeability Characterization

In January 2007, the NASA Administrator chartered the NASA Engineering and Safety Center (NESC) to form an Agency team to design and build a composite crew module in 18 months in order to gain hands-on experience in anticipation that future exploration systems may be made of composite materials. One of the conclusions from this Composite Crew Module Primary Structure assessment was that there was a lack of understanding regarding the ability for composite pressure shells to contain consumable gases, which posed a technical risk relative to the use of a metallic design. After the completion of the Composite Crew Module test program, the test article was used in a new program to assess the overall leakage/permeability and identify specific features associated with high leak rates. This document contains the outcome of the leakage assessment

Development of a Microfluidic Device Coupled to Microdialysis Sampling for the Pre-concentration of Cytokines

A proof-of-concept microfluidic device combined with heparin-immobilized magnetic beads was created to concentrate cytokine proteins collected from microdialysis samples. Cytokines are known to be related to several diseases such as cancer, and Parkinson\u27s diseases, so to be able to develop more effective diseases treatments their interactions have to be well understood. Amine-functionalized polystyrene and carboxyl-functionalized magnetic microspheres of ~6.0 ìm in diameter were used to immobilize heparin. The amount of heparin immobilized on polystyrene beads was 5.82 x 10-8 ± 0.36 x 10-8 M per 1.0 x 106 beads and for magnetic beads was 0.64 x 10-8 ± 0.01 x 10-8M per 1.0 x 106 beads. The minimum initial heparin concentration needed to bind ~ 100% cytokines was 36.8 ìM based on estimations for a fixed initial concentration (1.0 nM) of cytokines. For polystyrene beads, it was found that 0.1 and 1.0 nM ratCCL2 (MCP-1) bound to immobilized heparin at levels of 94.50 and 83.67%, respectively. For heparin immobilized magnetic beads, experimental percentages of cytokine bound to heparin were 70.38 ± 1.71 % (ratCCL2, 0.57 nM) and 11.07 % (ratTNF-á, 0.09 nM). The differences between experimental and estimated percentages of cytokine bound to heparin were 28.31 and 31.56% for ratCCL2 and ratTNF-á. A microfluidic system was designed and made of polydimethylsiloxane (PDMS) with soft lithography. The dimensions were as follows: a) Inlet channel width of 0.1 mm, b) circular trapping area of 3.6 mm in diameter, and c) outlet channel width of 0.2 mm. The equivalent circuit theory was used to estimate the pressure drop for each channel at a flow rate of 1.0 ìL/min. Estimated Reynolds numbers for each channel were low (0.17, 0.01, and 0.11) in agreement with the theory. Estimated pressure drops were 112.2, 0.20, and 30.28 Pa. Using different flow rates, the infusion of magnetic microspheres into the device and their spreading behavior within circular channel was observed and quantified. Spreading behavior of magnetic microspheres on a circular channel could be controlled by changing their flow rate. Controlling the behavior of magnetic microspheres is very crucial for pre-concentration of cytokine proteins on bead-based microfluidic devices. This microfluidic device is now ready for testing of the trapping and preconcentration of cytokines in real microdialysis samples

Building a Parameterized 4D Cardiac Model with Respiratory Motion from 2D MR Time Series

Projecte final de carrera fet en col.laboració amb Northeastern UniversityAtrial fibrillation (AF) is a growing problem in modern societies with an enormous impact in both short term quality of life and long term survival. A recently developed promising approach to cure AF uses radiofrequency (RF) ablation to carry out "pulmonary vein antrum isolation" (PVAI), electrically isolating the pulmonary veins from the rest of the atrium. However, the lack of proper 3D surgery training, planning, and guidance, along with current limitations in understanding of the true causes and mechanisms of AF, makes this surgery a very difficult task for the surgeons. Therefore recurrence rates and even failures of the procedure, as well as the risk for the patient, increase. The purpose of this work is to develop methods for automatically segmenting and tracking the heart in 4-D cardiac MRI datasets. The reconstructed heart surface will serve as a virtual computer model for the 3D surgery training, planning and guidance. The method used in this project is based on an active contour model for segmentation, followed by a spatial-time post-filtering and processing of the data obtained by the segmentation