No description available.

Erosion and weed dominance often limit the recovery of burned piñon-juniper woodlands. Soil water repellency (SWR) is one factor that may contribute to this by increasing overland flow and impeding seedling establishment. In spite of these effects, the extent of SWR within piñon-juniper woodlands is unknown. In this study, the extent, severity and thickness of SWR were sampled across 41 1,000 m2 plots within three 2009 Utah wildfires. Predictive models of SWR were built from ecological site characteristic data collected at each site. Across the study, SWR was found at 37% of the points sampled. SWR extent was strongly related to piñon-juniper canopy cover (r2 = 0.60) and was found to be significantly higher in tree/shrub mound zones (71%) as compared to interspaces (16%). Endorsed predictive models of SWR extent and severity had R2 adj values of 0.63 and 0.61; both models included piñon-juniper canopy cover and relative humidity the month before the fire as coefficient terms. These results suggest that as piñon-juniper canopy cover increases due to infilling processes in the coming years, post-fire SWR extent and severity will increase. As the effects of a changing climate in the Intermountain West link additively with infilling processes to increase the frequency and intensity of wildfires, the net effect will be stronger SWR over a greater spatial extent. To cope with these changes, land managers can apply the predictive models developed in this study to prioritize fuel control and post-fire restoration treatments with respect to SWR.

An intrinsic link exists between soil moisture and soil nitrogen. Factors that increase or decrease soil moisture can have a profound effect on soil nitrogen cycling, which may have later repercussions in the plant community. Post-fire soil water repellency is one factor that can limit soil moisture acquisition and may indirectly affect nitrogen cycling and weed invasion in woody islands of fertility. Plots centered on burned Juniperus osteosperma trees were either left untreated or treated with a surfactant to ameliorate water repellency. Two years later, soils were excavated from the untreated and treated field plots. In the greenhouse, half of each soil type received a surfactant treatment while the other half was left untreated. Pots were seeded with either Bromus tectorum or Pseudoroegneria spicata. Analysis of field soil prior to the greenhouse trial showed that untreated, repellent soils had inorganic nitrogen levels an order of magnitude higher than wettable, surfactant-treated soils. Greenhouse pots that had received a surfactant treatment in the field and/or greenhouse had similar soil water content, plant density, and above ground biomass, which were, respectively, 55-101%, 31 to 34 -fold, and 16 to 18 -fold greater than pots without a surfactant treatment. No species effects were found. This study indicates that water repellency can reduce wetting and retention of water in the soil while promoting the retention of high levels of inorganic nitrogen. However, the effects of soil water repellency on inorganic nitrogen appeared to have a minimal effect on plant growth compared to the effect of soil water repellency on water availability.

No description available.

Superhydrophobic fabrics have gained a huge interest in the industries recently. New legislation pushes the industries to eliminate the use of fluorinated materials in the production of these type of fabrics. Hydrophobic and self-cleaning garments textiles can deliver stable water repellent properties without the need for fluorinated chemicals and reduce the consumption of detergents. New methods that could be implemented in current textile industry processes without major changes in instruments or materials is essential to move this industry to the next level. Filament development with the hydrophobic structure without coating could be strategic on one side and tricky on the other side. It has been proved that a stable hydrophobic self cleaning surface needs a hierarchical micro-nano structure to present sustainable properties. In this thesis, we used common materials in the textile industry for filament production which are polyethylene terephthalate (PET) and high molecular weight polystyrene (PS) and low molecular weight polystyrene (LMPS) to shape the microstructures on the surface of filaments. By adding the common compatibilizer polystyrene-co-maleic anhydride (PSMA) to the blend, PS in the matrix of PET could migrate to the surface. Even 1% wt. of PSMA boosted the migration of PS polymer droplets to the surface. The blend including compatibilizer was compounded, melt-spun into the monofilament, drawn, and annealed for various time durations in the furnace. Next, the filaments were immersed in tetrahydrofuran(THF) to remove the PS component obtaining the rough surface. We investigated the effect of mixture components content and different process parameters such as draw ratio and annealing time on hydrophobicity by the aid of statistical design. Applying the Wilhelmy method for contact angle measurement, we could achieve an advancing contact angle (ACA)of 114º and the average ACA of 96º by making micro-size structure on raw PET with an average ACA of 80º and the intrinsic contact angle of around 70º.

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No description available.

Opportunistic premise plumbing pathogens (OPPPs) are responsible for many infections linked to drinking water. The annual cost of disease caused by these waterborne pathogens is $850 million. Key characteristics of these opportunistic waterborne pathogens include: disinfectant- resistant, biofilm formation, thermal-tolerance, desiccation-resistant, growth in amoebae and growth in low oxygen conditions. Methylobacterium spp. have been recognized as an emerging OPPP, so the purpose of this study was to investigate these waterborne bacteria in more detail to determine whether they have all characteristics of OPPPs. Seven Methylobacterium spp. strains were studied to measure growth in laboratory broth medium and drinking water, measure hydrophobicity on surfaces found in household plumbing, measure adherence and biofilm formation to surfaces found in household plumbing and measure susceptibility to hot water heater temperatures. Methylobacterium spp. were found to aggregate in lab broth medium and drinking water, hydrophobic on different surfaces in household plumbing, adhere readily and form biofilm on different surfaces and thermal-tolerant to water heater temperatures. These results support and identify Methylobacterium spp. as opportunistic premise plumbing pathogens. / Master of Science

Coal preparation plants use large quantities of water for cleaning processes. Upon cleaning, the spent water must be removed such that the final product moisture level meets market constraints. However, removal of free water from the surface of fine particles is difficult and costly, and often the results are less than desirable. Fine particles inherently have very large surface areas, and hence retain large amounts of water. Increased amounts of fines also cause denser particle packing, which creates relatively small capillaries in filter cakes and, thus, cause slower dewatering kinetics. As a result, dewatering costs for fine particles are much higher than for dewatering coarse particles. Considering the technical and economic issues associated with dewatering coal and mineral fines, an extensive matrix of laboratory- and pilot-scale dewatering tests have been conducted to evaluate the use of novel dewatering aids. The reagents are designed to lower the surface tension of water, increase the hydrophobicity of the particles to be dewatered, and increase the capillary radius by hydrophobic coagulation. All of these are designed to lower the moisture of the filter cakes produced in mechanical dewatering processes. Laboratory-scale dewatering tests confirmed that using the novel dewatering aids can lower the final cake moisture of coal by 20-50%, while increasing the dewatering kinetics. Several on-site, pilot-scale tests were conducted to demonstrate that the process of using the novel dewatering aids can be scaled. Based on the laboratory- and pilot-scale tests conducted, a scale-up model for the process of using the novel dewatering aids has been developed. It can predict the final cake moistures as a function of vacuum pressure, filtration time and specific cake weight. The model can be useful for the scale-up of vacuum disc filters (VDF) and horizontal belt filters (HBF). Simulation results indicate that dewatering aids can be very effective, especially when used in conjunction with HBF due to its ability to control cake thickness and drying cycle time independently. In light of the promising laboratory- and pilot-scale test results, an industrial demonstration of the novel dewatering aids has been conducted at the Smith Branch impoundment site, which contains 2.9 million tons of recoverable coal. When the reagent was used for dewatering flotation products using a VDF, the moisture content was reduced from 26 to 20% at 0.5 lb/ton of reagent addition and to 17.5% at 1 lb/ton. The use of the dewatering aid also improved the kinetics of dewatering, increased the throughput, and reduced the power consumption of vacuum pumps by 30%. The novel dewatering aids were also tested successfully for dewatering of kaolin clays. In this case, the mineral was treated with a cationic surfactant before adding the dewatering aids. This two-step hydrophobization process was able to reduce the cake moisture and also increase the throughput. / Ph. D.

Fresh produce is increasingly associated with foodborne outbreaks. In order to develop effective intervention and measures to reduce microbial risks, it is essential to attain a better understand the mechanisms of attachment of foodborne pathogens to fruits and vegetables. Using lettuce as a model, the attachment of Escherichia coli O157:H7 to produce surfaces was studied. Strains expressing various extracellular proteins (curli, O157-antigen, and intimin) known to influence attachment of E. coli to intestinal cells were evaluated for their physicochemical properties and ability to adhere to cut edge and whole leaf lettuce. Escherichia coli O157:H7 strains included: 0018, 43894 and 43895 (curli producing and non-producing); 86-24 (WT), F-12 (O157-antigen negative), pRFBE (O-antigen replaced on plasmid); and 86-24, 86-24Ã eae10 (intimin negative). The eleven strains were surveyed for their hydrophobicity and cell charge using hydrophobic interaction chromatography (HIC) and electrostatic interaction chromatography (ESIC) techniques. Iceberg lettuce squares (2 x 2 cm) were inoculated with E. coli O157:H7 strains separately (7.0 log CFU/square) and dried in a laminar flow hood. Lettuce was sampled before (unrinsed) and after being rinsed twice with sterile de-ionized water (rinsed). Strips (2 mm wide) of each cut edge of the lettuce were aseptically removed. Cut-edge and whole-leaf samples were homogenized and spiral plated onto Luria-Bertani agar, supplemented with nalidixic acid (50ppm), to assess levels of bacteria remaining on the lettuce leaf after rinsing. The rinse steps were not effective in significantly removing bacteria from lettuce (p>0.05). Curli-producing and non-producing strains preferentially attached to cut edge versus the whole leaf portions of lettuce (p<0.05); however the 86-24 strains showed no preference for attachment. With the exception of 0018 curli-producing and non-producing strains, presence/absence of extracellular proteins surveyed did not influence attachment of E. coli O157:H7 to either cut edge or whole leaf lettuce. There was significantly greater attachment of the curli-producing 0018 strain over the curli non-producing 0018 strain to cut and whole lettuce surfaces (p<0.05). Production of curli and O-polysaccharide significantly increased (p<0.05) the cell's overall hydrophobicity of the cell; however this did not affect attachment (p<0.05). The overall cell charge of all strains was negative; however, charge did not affect attachment of E. coli O157:H7 to lettuce. The presence of extracellular appendages (curli, O157-antigen, intimin) as well as hydrophobicity and cell charge properties had no affect on attachment of the cell to lettuce. / Ph. D.