Spin resonance excitation of Gd-based contrast agents for thermal energy deposition

A thesis submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctor of Philosophy. Johannesburg, 2016The theoretical and experimental investigation of electron spin-resonance relaxation to deposit thermal energy into liquid gadolinium-based contrast agents for cancer hyperthermia treatment is presented. Previous works suggest that using protons in water are inadequate, with a thermal deposition rate of approximately 1 ◦C per two years. A novel component of this research relies on the use of gadolinium-chelated molecules, which are currently used as contrast agents in clinical MRI scans. The chelating agents, or ligands, investigated are Gadobenate (MultiHance R ), Gadopentetate (Magnevist R ), Gadoterate (DotaremR ) and Gadoteridol (ProHance R ). The gadolinium atom has seven unpaired electrons in its inner f shell orbital and as a result has a 660 times stronger paramagnetic response when placed in an external magnetic field. The research tests the hypothesis that by using an appropriate external homogeneous DC magnetic field, together with a radiofrequency excited resonator, that a measurable amount of thermal energy is deposited into a liquid gadolinium-based contrast agent. The aim of this research is to ultimately discover a new cancer hyperthermia treatment. The research theory suggests that a temperature rate of 13.4 ◦C · s−1 can be achieved using the gadolinium-based contrast agents under certain experimental conditions, and a maximum of 29.4 ◦C · s−1 under more optimal conditions. The temperature rates are calculated using parameter values commonly found in literature and practice. The simulation and design of the DC magnetic field coil system is discussed, together with the simulation results and design parameters of the radiofrequency loop-gap resonator. The experimental results and analysis indicate that the selected contrast agents have varied responses based on their chemical nature and that only two out of the four contrast agents, Dotarem and ProHance, show a measurable effect albeit sufficiently small that statistical techniques were necessary to distinguish the effect from background. A model fit to the data is performed in order to determine the spin-lattice relaxation time of the contrast agents under the specified experimental conditions. The model estimate is significantly smaller than the values found in literature under similar conditions, with a spin-lattice relaxation time τ1e of approximately 0.2 ps compared to the literature value of 0.1 ns. Although the observed electron spin resonance heating rate is in the milli-Watt range it is still notably larger (167 000 times) compared to the heating rate obtained using protons. The low temperature rates suggest that a more suitable agent or molecule with a larger spin-relaxation time be used, in order to achieve clinical useful temperature rates in the range of 14 ◦C · s−1.MT201

The Affect Effect: State Affect, Cognitions and IT Usage

This study presents state affect as a necessary theoretical and empirical component of information systems (IS) research models addressing the cognitions regarding, and usage of, information technology (IT). We position state affect as a powerful predictor of trusting cognitions and explain how state affect may also directly impact IT use. We tested our research model using data from 376 users of Microsoft Excel. Results indicate that positive and negative affect influence various trusting cognitions as well as directly impact post-adoptive use intentions. Our findings offer particular implications IS research models intending to comprehensively model cognitions and attitudes regarding IT and IT usage

Cluster analysis of gene expression data on cancerous tissue samples.

The cluster analysis of gene expression data is an important unsupervised learning method that is commonly used to discover the inherent structure in the large amounts of data generated by microarray measurements. The focus of this research is to develop a novel clustering algorithm that adheres to the definition of unsupervised learning whilst minimising any sources of bias. The developed diffractive clustering algorithm is based on the fundamental diffraction properties of light, which presents a novel view and framework for clustering data. The algorithm is tested on multiple cancerous tissue data sets that are well established in the literature. The overall result is a clustering algorithm that outperforms the conventional clustering algorithms, such as k-means and fuzzy cmeans, by 10% in terms of accuracy and more than 30% in terms of cluster validity. The diffraction-based clustering algorithm is also independent of any parameters and is able to automatically determine the correct number of clusters in the data

Chemical Analysis of Fish Tissue: Kentucky Army National Guard Wendell H. Ford Western Kentucky Training Site, Muhlenberg County, Kentucky

Thirty-one analytes were measured in fish tissue taken from largemouth bass, catfish, and bluegill harvested from lakes and ponds in reclaimed and unreclaimed coal-mine spoil of Pennsylvanian age. The spoil area is approximately 7,756 acres created primarily from surface mining, and has been used in increasing intensity since 1969 as a training site by the Kentucky Army National Guard. Four fish were harvested for analysis from the area of unreclaimed spoil that resulted from mining prior to 1977, and 15 fish were harvested for analysis from the part of the training facility that was reclaimed by 1985. Twenty-six analytes had values above the method reporting limit, and only one sample, L15-8A, had a mercury concentration of 1.22 mg/kg. This concentration is slightly above the federal Food and Drug Administration action concentration level of 1 mg/kg

Water-Quality and -Quantity Data for Abandoned Underground Coal Mines in Eastern Kentucky

Water-quality and -quantity analyses were performed between 1997 and 2003 by the Kentucky Geological Survey under contract from the Kentucky River Authority and the Kentucky Infrastructure Authority to study abandoned underground coal mines as possible water supplies for communities in the Eastern Kentucky Coal Field. The steep terrain of the coal field limits surface-water supplies, and groundwater systems are difficult to locate and often have too low a yield to provide community water supplies. KGS has been working with the Kentucky River Authority, the Kentucky Infrastructure Authority, and local government officials to search for water supplies in abandoned underground coal mines. The data in the appendices of this report are interpreted in Cumbie and others (2006)

Hydrogeologic Investigations of Pavement Subsidence in the Cumberland Gap Tunnel

Cumberland Gap Tunnel was constructed under Cumberland Gap National Historical Park in 1996 to improve transportation on a segment of U.S. 25E, connecting Kentucky and Tennessee and restoring Cumberland Gap to its historical appearance. The concrete pavement in the tunnel started to subside in 2001. Ground penetrating radar surveys revealed voids in many areas of the limestone roadbed aggregate beneath the pavement. To investigate possible hydrogeologic processes that may have caused favorable conditions for voids to form in the aggregate, we studied geology, groundwater flow, and groundwater chemistry in the tunnel using a variety of methods, including bore drilling, packer test, dye tracing, groundwater- and surface-flow monitoring, water-chemistry modeling, and an aggregate dissolution experiment. The study revealed that the aggregate receives a large volume of groundwater from much of the bedrock invert, but the flow velocity is too slow to transport small particles out of the aggregate. Calcite saturation indices calculated from water-chemistry data suggest that the groundwater was capable of continuously dissolving calcite, the primary mineral in the limestone aggregate. Water samples taken during different flow conditions indicate that groundwater under low-flow conditions. The dissolution experiment showed that all the limestone aggregate placed beneath the roadbed and in contact with groundwater lost mass; the highest mass loss was 3.4 percent during a 178-day period. The experiment also suggested that water with higher calcite-dissolving potential removed limestone mass quicker than water with low calcite-dissolving potential. We recommend that the limestone aggregate be replaced with noncarbonate aggregate, such as granite, to prevent dissolution and future road subsidence

RNAcentral : a hub of information for non-coding RNA sequences

RNAcentral is a comprehensive database of non-coding RNA (ncRNA) sequences, collating information on ncRNA sequences of all types from a broad range of organisms. We have recently added a new genome mapping pipeline that identifies genomic locations for ncRNA sequences in 296 species. We have also added several new types of functional annotations, such as tRNA secondary structures, Gene Ontology annotations, and miRNA-target interactions. A new quality control mechanism based on Rfam family assignments identifies potential contamination, incomplete sequences, and more. The RNAcentral database has become a vital component of many workflows in the RNA community, serving as both the primary source of sequence data for academic and commercial groups, as well as a source of stable accessions for the annotation of genomic and functional features. These examples are facilitated by an improved RNAcentral web interface, which features an updated genome browser, a new sequence feature viewer, and improved text search functionality. RNAcentral is freely available at https://rnacentral.org