Search Results

Prediction of Partition Coeffecients and Permeability of Drug Molecules in Biological Systems with Abraham Model Solute Descriptors Derived from Measured Solubilities and Water-to-Organic Solvent Partition Coefficients

Description: Book chapter on the prediction of partition coefficients and permeability of drug molecules in biological systems with Abraham model solute descriptors derived from measured solubilities and water-to-organic solvent partition coefficients.
Date: February 10, 2012
Creator: Acree, William E. (William Eugene); Grubbs, Laura M. & Abraham, M. H. (Michael H.)
Item Type: Book Chapter
Partner: UNT College of Arts and Sciences

Hybrid Approach for Energy-Aware Synchronization

Description: This book chapter discusses a time synchronization scheme for wireless sensor networks that aims to save sensor battery power while maintaining network connectivity for as long as possible.
Date: December 2010
Creator: Akl, Robert G.; Saravanos, Yanos & Haidar, Mohamad
Item Type: Book Chapter
Partner: UNT College of Engineering

Soybean Oil Derivatives for Fuel and Chemical Feedstocks

Description: Plant based sources of hydrocarbons are being considered as alternatives to petrochemicals because of the need to conserve petroleum resources for reasons of national security and climate change. Changes in fuel formulations to include ethanol from corn sugar and methyl esters from soybean oil are examples of this policy in the United States and elsewhere. Replacements for commodity chemicals are also being considered, as this value stream represents much of the profit for the oil industry and one that would be affected by shortages in oil or other fossil fuels. While the discovery of large amounts of natural gas associated with oil shale deposits has abated this concern, research into bio-based feedstock materials continues. In particular, this chapter reviews a literature on the conversion of bio-based extracts to hydrocarbons for fuels and for building block commodity chemicals, with a focus on soybean derived products. Conversion of methyl esters from soybean triglycerides for replacement of diesel fuel is an active area of research; however, the focus of this chapter will not reside with esterification or transesterification, except has a means to provide materials for the production of hydrocarbons for fuels or chemical feedstocks. Methyl ester content in vehicle fuel is limited by a number of factors, including the performance in cold weather, the effect of oxygen content on engine components particularly in the case of older engines, shelf-life, and higher NOx emissions from engines that are not tuned to handle the handle the enhanced pre-ignition conditions of methyl ester combustion [1]. These factors have led to interest in synthesizing a hydrocarbon fuel from methyl esters, one that will maintain the cetane number but will achieve better performance in an automobile: enhanced mixing, injection, and combustion, and reduce downstream issues such as emissions and upstream issues such as fuel preparation and transportation. ...
Date: January 2013
Creator: McFarlane, Joanna
Item Type: Book
Partner: UNT Libraries Government Documents Department

Quality Assessment of Retinal Fundus Images using Elliptical Local Vessel Density

Description: Diabetic retinopathy is the leading cause of blindness in the Western world. The World Health Organisation estimates that 135 million people have diabetes mellitus worldwide and that the number of people with diabetes will increase to 300 million by the year 2025 (Amos et al., 1997). Timely detection and treatment for DR prevents severe visual loss in more than 50% of the patients (ETDRS, 1991). Through computer simulations is possible to demonstrate that prevention and treatment are relatively inexpensive if compared to the health care and rehabilitation costs incurred by visual loss or blindness (Javitt et al., 1994). The shortage of ophthalmologists and the continuous increase of the diabetic population limits the screening capability for effective timing of sight-saving treatment of typical manual methods. Therefore, an automatic or semi-automatic system able to detect various type of retinopathy is a vital necessity to save many sight-years in the population. According to Luzio et al. (2004) the preferred way to detect diseases such as diabetic retinopathy is digital fundus camera imaging. This allows the image to be enhanced, stored and retrieved more easily than film. In addition, images may be transferred electronically to other sites where a retinal specialist or an automated system can detect or diagnose disease while the patient remains at a remote location. Various systems for automatic or semi-automatic detection of retinopathy with fundus images have been developed. The results obtained are promising but the initial image quality is a limiting factor (Patton et al., 2006); this is especially true if the machine operator is not a trained photographer. Algorithms to correct the illumination or increase the vessel contrast exist (Chen & Tian, 2008; Foracchia et al., 2005; Grisan et al., 2006;Wang et al., 2001), however they cannot restore an image beyond a certain level of quality degradation. On ...
Date: January 1, 2010
Creator: Giancardo, Luca; Meriaudeau, Fabrice; Karnowski, Thomas Paul; Chaum, Edward & Tobin Jr, Kenneth William
Item Type: Book
Partner: UNT Libraries Government Documents Department

Processing of Soybean Oil into Fuels

Description: Abundant and easily refined, petroleum has provided high energy density liquid fuels for a century. However, recent price fluctuations, shortages, and concerns over the long term supply and greenhouse gas emissions have encouraged the development of alternatives to petroleum for liquid transportation fuels (Van Gerpen, Shanks et al. 2004). Plant-based fuels include short chain alcohols, now blended with gasoline, and biodiesels, commonly derived from seed oils. Of plant-derived diesel feedstocks, soybeans yield the most of oil by weight, up to 20% (Mushrush, Willauer et al. 2009), and so have become the primary source of biomass-derived diesel in the United States and Brazil (Lin, Cunshan et al. 2011). Worldwide ester biodiesel production reached over 11,000,000 tons per year in 2008 (Emerging Markets 2008). However, soybean oil cannot be burned directly in modern compression ignition vehicle engines as a direct replacement for diesel fuel because of its physical properties that can lead to clogging of the engine fuel line and problems in the fuel injectors, such as: high viscosity, high flash point, high pour point, high cloud point (where the fuel begins to gel), and high density (Peterson, Cook et al. 2001). Industrial production of biodiesel from oil of low fatty-acid content often follows homogeneous base-catalyzed transesterification, a sequential reaction of the parent triglyceride with an alcohol, usually methanol, into methyl ester and glycerol products. The conversion of the triglyceride to esterified fatty acids improves the characteristics of the fuel, allowing its introduction into a standard compression engine without giving rise to serious issues with flow or combustion. Commercially available biodiesel, a product of the transesterification of fats and oils, can also be blended with standard diesel fuel up to a maximum of 20 vol.%. In the laboratory, the fuel characteristics of unreacted soybean oil have also been improved by dilution with ...
Date: January 1, 2011
Creator: McFarlane, Joanna
Item Type: Book
Partner: UNT Libraries Government Documents Department