This thesis deals with electrical conductivity in thin films. Classical and quantum size effects in conductivity are discussed including some experimental evidence of quantum size effects. The component conductivity along the applied electric field of a thin film in a transverse magnetic field is developed in a density matrix method.

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This study investigates of the effect of nanoparticle volume fractions, NaCl concentration and pH on size of agglomerates, electrical conductivity and zeta potential of alumina nanofluids. The volume fractions used were 1, 2, 3 and 5 vol%. Different base fluids were prepared by adding NaCl (100, 300 and 500 ppm) or adjusting the pH (9, 7, 5 and 3). The results showed that the size of nanoparticle agglomerates was increased with an increase in nanoparticles concentration and NaCl concentration. Also, the electrical conductivity was increased with an increase in nanoparticle concentration and NaCl concentration. The size of nanoparticle agglomerates was 110 nm and the electrical conductivity was 290.2 μS/cm at pH 3 and 0 ppm, which was the highest value of electrical conductivity and smallest agglomerates nanoparticle size at 1 vol% with no salt. The highest value was 1830 μS/cm at pH 9 and 500 ppm of NaCl with 5 vol% of nanoparticles.

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Solid Oxide Fuel Cells have attracted much attention over the past few decades due to their huge potential for clean power generation in stationary, portable and transport applications and our increasing need for sustainable energy resources. The purpose of this research is to develop an interconnect and cathode material for use in solid oxide fuel cells which demonstrates desired properties of high electrical conductivity, excellent chemical stability at high temperatures, desirable thermal expansion characteristics and which can be easily manufactured by sintering in conditions acceptable with other cell components. The present work was initiated to study the synthesis and properties of five different perovskite oxides comprising of Lanthanum in combination with different mol% of Chromium, Ferrum, Cobalt and Nickel. A polymer complexing route with slight modifications was used to prepare the precursor powders. The powder x-ray diffraction patterns at room temperature show that all samples were formed in single phase. The powders in the form of pellets were sintered at 1400°C. The temperature dependent resistivity data was measured and the conductivity data was calculated. This conductivity data have been fitted with the Arrhenius model for entire studied range of temperature (25-800°C) to calculate the activation energy. La based perovskite oxides were characterized using X-ray diffraction (XRD), and scanning electron microscopy (SEM). Electrical properties and microstructural studies show potential applications of the materials as interconnect and cathode for Solid Oxide Fuel Cell. The material which has the above desired properties was proposed and component modifications for tailoring such properties were shown for SOFCs and other similar applications.

Subsoil compaction is a major yield limiting factor for most agricultural crops. Tillage is the most efficient method to quickly treat compacted subsoil, but it is also expensive, increases erosion, and accelerates nutrient cycling. The use of real-time electrical conductivity (EC) and near-infrared (NIR) reflectance values to differentiate compacted areas from uncompacted areas was studied. This method has potential to reduce monetary and time investments inherent in traditional grid sampling and the resultant deep tillage of an entire field. EC and NIR reflectance are both very sensitive to spatial variability of soil attributes. The objective of this research was to determine whether the amount of soil moisture affects the efficacy of EC and NIR spectroscopy (at 2151.9 nm) in identifying subsoil compaction through correlation analysis, and also to determine whether a minimum level of compaction was necessary for these same methods to detect compaction in three different soil textures across a variable water gradient. Bulk density measurements were taken in late 2007 from plots traversing an induced soil moisture gradient, and low, medium, and high levels of compaction at three locations with different soil textures. A Veris Technologies (Salina, KS) Near-Infrared Spectrophotometer equipped with an Electrical Conductivity Surveyor 3150 was used to measure and geo-reference EC and NIR reflectance data over the same plots. Analysis of the data for a correlation between compaction (bulk density values) and EC, as well as compaction and NIR reflectance, produced clear results. It was found that electrical conductivity is not significantly different between compacted or uncompacted soils even when tested at all moisture extremes and in different soil textures in Utah. Also, NIR spectroscopy was unsuccessful at identifying subsoil compaction because all tested procedures to induce a spectrometer into the soil resulted in changes the physical properties of the soil.

Sulfate-bearing soils are a problem in highway construction as they combine with materials used for lime stabilization to form minerals, particularly ettringite, that expand and induce heave in the stabilized soil. This research involves quantifying sulfate in soils that may be potentially used in highway construction using electromagnetic induction. The objectives are to: 1) document electrical conductivity (EC) variability within selected sites that contain sulfate-bearing materials, and 2) determine if electromagnetic induction has potential for locating hazardous levels of sulfate-bearing materials. The 0.43 ha study area is located in the Blackland Prairies and is a Vertisol known to contain gypsum at the time of site selection. Apparent EC using a model EM38 electromagnetic induction instrument was measured at 200 locations in July and November 2003, using a sampling grid with 5-m spacings. Representative rows and columns were selected from the map of apparent electrical conductivity, and soil cores taken to a depth of 1.5 m at 29 points. Soil samples were obtained by dividing cores into depth increments of 0 to 25 cm, 25 to 75 cm, and 75 to 150 cm. Laboratory analyses were run for each sample and included moisture content, EC and soluble cations and anions of the saturated paste extract, and percent gypsum. Elevation measurements were made to determine if changes in elevation related to EC measurements. Apparent EC proved to be more successful at detecting soluble salts during the dry sampling period (July) when the effect of soil moisture content was less. For July data, EC and gypsum were significantly correlated in the deepest samples (r2 = 0.51 and 0.15, respectively) to apparent EC. Further, soluble sulfate was significantly correlated to apparent EC (r2 = 0.30) at a depth of 25 to 75 cm. Results suggest that the EM38 can be used successfully to map variability of soil salinity across a field, but although correlation exists between apparent EC and sulfate-bearing materials, it is not sufficiently strong to serve as a good predictor for conditions surrounding lime-induced heave in soil.

Conductive and flexible nanocomposites can have wide applications in textiles, including wearable sensors, antenna, electrodes, etc. The objective of this research is to develop electrically conductive fibers and films that are flexible and deformable for use in textile structures able to accommodate the drape and movement of the human body. To achieve this objective, we evaluate the electrical properties of PEDOT:PSS/nickel nanostrand as well as nylon 6/nickel nanostrand nanocomposites. Nickel nanostrands (NiNS) were first used to reinforce an intrinsically conductive polymer, Poly(3,4-ethylenedioxythiophene) (PEDOT:PSS), in order to fabricate nanocomposite films with high electrical conductivity. The electrical properties of the films were evaluated by the Van der Pauw method. The addition of 10 wt% nanostrands in PDOT:PSS provided a two order of magnitude improvement in electrical conductivity. In addition to PDOT:PSS, nylon 6/NiNS nanocomposite fibers were produced using electrospinning and exhibited diameters in the sub-micron range. The NiNS-reinforced fibers had electrical conductivity that exceeded the ESD range, which offers the potential for use in protective textile applications. / text

Balancing plant growth between vegetative and reproductive status is crucial for producing high quality greenhouse tomatoes while maintaining high productivity in long crop production seasons. In the tomato industry, certain plant morphological characteristics are used to classify plant growth status as vegetative, reproductive or balanced. Each growth status has been associated with distinct greenhouse environments which reduce or enhance transpiration.The effect of different transpiration on vegetative, reproductive or balanced plant growth status as defined by a set of plant morphological characteristics was investigated. To validate the practical significance of such classification, growth status was quantified as the relationship between variations in morphological characteristics and the fresh weight distributed between reproductive and vegetative organs.Two electrical conductivity (EC) levels of the nutrient solution, high and standard EC, were combined with two potential transpiration environments, low and high potential transpiration. All treatment combinations were contrasted with a reference greenhouse environment similar to the industry standard.Electrical conductivity had the greatest effect on morphological characteristics which were reduced in size with high EC. For each EC level, the response decreased for increasing potential transpiration. Stem diameter had the greatest sensitivity to the different treatment combinations. For the standard EC and for the range of potential transpirations achieved, stem diameter varied within a relatively narrow range, close to the industry standard 'threshold' used to classify a balanced tomato plant. A reproductive plant growth status, as evaluated by a smaller value than this threshold, was observed only with high EC. No vegetative plants were produced within any potential transpiration or EC treatment combination.High EC decreased the cumulative total fresh weight production by the same magnitude for all potential transpirations. Potential transpiration had a minimal effect on the total fresh weight production or on its components. As a result, the fresh weight ratio between reproductive and vegetative plant organs was similar for most potential transpiration environments, regardless of variations in stem diameter. Therefore, within the range of potential transpiration environments achieved, the distinction between vegetative and reproductive growth status as an indicator of fresh weight distribution and fruit yields could not be quantitatively validated.