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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

ESTIMATION OF EVAPOTRANSPIRATION OF COTTONWOOD TREES IN THE CIBOLA NATIONAL WILDLIFE REFUGE, CIBOLA, ARIZONA

JETTON, AMITY J. 29 May 2008 (has links)
No description available.
42

Essential oil treatment of VTC wood

Scouse, Adam A. 13 September 2012 (has links)
Western juniper and cinnamon essential oils were combined with ethanol at 2.5, 5, and 10% concentrations by weight and applied to hybrid poplar (Populus trichocarpa x P. deltoids) veneers by vacuum soaking to produce a naturally durable wood veneer with increased mechanical properties for use in structural composites. Half of these veneers were then modified using viscoelastic thermal compression to increase veneer density and modulus of elasticity. Following densification, unprocessed and VTC processed veneers receiving an essential oil treatment were subjected to an AWPA E21-06 Formosan termite exposure test, AWPA E24-06 mold box test, and brown rot (Gloeophyllum trabeum) decay bending test. While VTC processing drastically reduced the abundance of chemical components inherent within essential oil treatments, veneer specimens without VTC processing showed increased durability. A 10% juniper oil treatment drastically reduced Formosan termite attack on hybrid poplar veneers while a 10% cinnamon oil treatment significantly reduced mold growth. Timbor��, an industrial powdered borate treatment, withstood VTC processing and inhibited Formosan termite attack and mold growth. Tests to evaluate the effectiveness of essential oil treatments against brown rot were unsuccessful. Results suggest that incorporating a disodium octaborate tetrahydrate (DOT) treatment prior to VTC processing could help improve VTC wood durability. / Graduation date: 2013
43

Environmental Economics: A Case Study for the Big Cottonwood Canyon Watershed

Hull, Robert 01 May 2013 (has links)
Environmental economics is the application of economic principles to the study of how natural resources are developed and managed. The methodologies used attempt to value ecosystem services provided by healthy, functioning natural lands and ecosystems. Ecosystem services attributed to natural lands contribute significant human welfare benefits that go largely undervalued or misrepresented in the decision-making process for the development of land. As environmental valuation methodologies and techniques continue to advance, policy decisions will be better able to create outcomes that maximize benefits for targeted populations and landscapes. The purpose of this paper is to first describe the methodologies used in environmental economics. These methodologies will then be applied to the Big Cottonwood Canyon Watershed located to the east of Salt Lake City, Utah. The case study will describe the ecosystem services provided by the watershed and value them. Using these values, the study focuses on the proposed development of SkiLink, a gondola system that would connect two separate ski resorts in two separate canyons – the Solitude Mountain Resort, located in Big Cottonwood Canyon, and Canyons Resort, located near Park City, Utah. The debate over the proposed SkiLink focuses on weighing its potential contribution to Utah’s economy against its potential environmental consequences. Based on a detailed analysis of the economic benefits and ecosystem losses created by the proposal, a cost-benefit analysis of the project will be presented along with recommendations for further study of potential development that would likely accompany the building of SkiLink.
44

A study of the glycosides in the hot water extract of the green bark of Populus trichocarpa

Estes, Timothy K., January 1967 (has links) (PDF)
Thesis (Ph. D.)--Institute of Paper Chemistry, 1967. / Includes bibliographical references (p. 79-81).
45

The influence of geomorphology and flow regulation on riparian cottonwoods

Willms, Chad Ryan, University of Lethbridge. Faculty of Arts and Science January 2005 (has links)
This study investigated the influence of geomorphic context and flow regulation on cottonwood (Populus) age structure, stand size, recruitment rates, and annual radial growth patterns along the Oldman River in southern Alberta. Dendrochronological techniques were used to age trees, establish population structures, and measure annual radial growth on three reaches in differing geomorphic contexts. Cottonwoods within a narrow, 'constrained' reach were more negatively impacted by partial dewatering of the river, but responded more favorably to increased late-summer flows combined with suitable recruitment conditions than the trees within a wide, 'alluvial' reach. A positive linear relationship between early-summer peak discharge and annual radial growth was found only on the alluvial reach. However, these trees also had the slowest growth rates, likely due to competition between trees because alluvial reaches often support large, dense stands of cottonwoods. This study demonstrates the need to consider the geomorphic context when studying cottonwood responses to river regulation. / xvi, 141 leaves : ill. ; 29 cm.
46

Succession of arbuscular mycorrhizal fungi causes, consequences, and considerations /

Piotrowski, Jeffrey Scott. January 2007 (has links)
Thesis (Ph. D.)--University of Montana, 2007. / Title from title screen. Description based on contents viewed Aug. 12, 2008. Includes bibliographical references.
47

Implications of Geochemistry and Textures of Titanite for the Geologic Histories of the Notch Peak Intrusion and Little Cottonwood Stock, Utah

Henze, Porter 27 July 2020 (has links)
Textural and compositional variations in titanite, along with whole-rock geochemistry, provide constraints on the emplacement and cooling histories of two plutons: the Jurassic Notch Peak pluton and the Oligocene Little Cottonwood stock, both in Utah. Titanite textures observed with back-scattered electron (BSE) imaging along with their compositions were used to determine four periods of growth: cores, rims, interstitial overgrowths, and secondary replacements. Brightness in BSE images correlates mostly with rare earth elements (REE). REE patterns in cores and rims are compositionally similar in both plutons, although the Notch Peak intrusion tend to be slightly more enriched in REE. Overgrowths and secondary replacements typically have lower concentrations of REE and Fe and higher Al, Mn, F, and U. They also have similar δ18O values to primary titanite, indicating alteration and recrystallization from exolved magmatic fluids rather than meteoric sources. In the Notch Peak intrusion, titanite grains usually have simple, oscillatory zoned textures that include cores which include bright sector zones. These are overprinted by secondary titanite that grows within and replaces the primary titanite grain. At some localities, Notch Peak titanites have been hydrothermally altered to fine-grained aggregates of rutile or brookite, magnetite, quartz, and plagioclase. These observations indicate a simple cooling path after magmatic intrusion, followed by hydrothermal alteration for the Notch Peak intrusion. The Little Cottonwood stock contains titanite grains that are distinctly different from those in the Notch Peak intrusion. They typically contain a distinct patchy core with rounded, resorbed ilmenite inclusions. Surrounding the core is a mantle of oscillatory zoned titanite. On many grains, narrow rims of secondary overgrowths are observed as well as interstitial titanite growing in between chloritized biotite sheets. The cores of these titanite grains suggest that a more reduced, ilmenite-rich magma mixed into an oxidized felsic magma, destabilizing existing ilmenites and forming its patchy texture. This was followed by hydrothermal overgrowths and interstitial titanite, like Notch Peak, but to a lesser extent. Although both plutons had similar emplacement settings–subduction related intrusion into Paleozoic limestone–their whole rock and titanite chemistries are different. The Notch Peak intrusion is more chemically evolved and less mafic than the Little Cottonwood stock. The patchy cores with Fe-Ti oxide inclusions found in the Little Cottonwood stock, along with the abundance of mafic enclaves in the pluton, provide evidence for magma mixing, while no evidence is observed in the Notch Peak intrusion for magma mixing.
48

An Archaeological Survey of North Cottonwood Canyon, San Juan County, Southeastern Utah

Davis, Larry D. 01 April 1975 (has links)
The results of an archaeological survey of North Cottonwood Canyon, San Juan County, southeastern Utah, are herein reported. The purpose and background leading up to the survey are followed by a physical description of the canyon and a description of the 36 archaeological sites recorded. The cultural material collected and/or observed at the sites, including architecture, ceramics, and other miscellaneous artifacts, is described and discussed. This is followed by a distributional analysis between sites. This includes altitude, slope, water resources, and vegetation. Cultural materials in North Cottonwood Canyon are then compared with materials from related areas, including Montezuma Canyon, Beef Basin, Salt Creek, Indian Creek, Cedar Mesa, Hammond Canyon, and Glen Canyon. This is followed by the Conclusion, which discusses the time periods the canyon was inhabited, the lifeway of the prehistoric inhabitants, and some possibilities for further work that hopefully will be conducted in the canyon at a future date.
49

Investigations of factors affecting pine and cottonwood pyrolysis oil aging

Naske, Caitlin Durnin 10 December 2010 (has links)
Studies of aging processes were conducted on pyrolysis oils produced from pine and cottonwood biomass (clear wood, whole tree, bark and needles/leaves). Accelerated aging at 80 °C for up to 504 h was employed to investigate the short and long-term effects of feedstock, phase separation, char particulates, and solvent addition on pyrolysis oil properties. Feedstock containing forestry residue was found to increase water content of neat pyrolysis oil and the collection method (total vs. fractionated) affects all of the properties with the largest impact on viscosity and as produced molecular weight. Post-condensation liquid filtration did not prevent aging-related water content or molecular weight increases during aging but did retard aging reactions in pine clear wood and pine bark pyrolysis oils. Methanol addition retarded the aging reactions in pine needle fractionated pyrolysis oil; at 15 wt% phase separation was prevented and molecular weight increased 11 % after 504 h of aging.
50

Using physiological parameters to refine estimates of short rotation poplar performance and productivity

Stewart, Leah Frances 07 August 2020 (has links)
Short rotation woody crops (SRWC) are bred for rapid growth properties. Knowledge of how varying environmental conditions and endophytic bacteria impact physiology are needed to make planting recommendations. Three eastern cottonwood (EC) and three hybrid poplar (HP) varietals were planted in replicate blocks at upland and alluvial sites. Whole-tree water use and water use efficiency (WUE) were measured using heat-dissipation sap flow and related to overall productivity. Productivity measurements were higher at the upland site. Sap flow was higher at the upland site and for endophyte treated individuals. WUE was higher at the alluvial site and for EC. WUE and leaf area index (LAI) were significantly correlated with biomass (negatively and positively respectively). Overall, HP performed better at the upland site, EC at the alluvial site. These results are beneficial in further testing of optimal site and genotype pairings for SRWC.

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