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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.
111

An investigation of the kinetics for the fast pyrolysis of loblolly pine woody biomass

Williams, Alexander W. 23 May 2011 (has links)
In the search for fossil fuel alternatives the production of bio-oil through the pyrolysis of biomass is one method which has shown evidence of scalability, meaning that the technology could be scaled up for the processing of biomass on the order of tons per day. Pyrolysis is the thermal degradation of compounds in the absence of oxygen. Of particular interest is the pyrolysis of sustainable energy crops such as Loblolly pine (Pinus taeda). The goal of this study is to develop a new method of characterizing the fast pyrolysis of biomass for the advancement of reactor design. The objectives are to determine bulk kinetic coefficients for the isothermal fast pyrolysis of biomass, evaluate the interchangeability of fast and slow pyrolysis kinetic parameters and compare generally accepted pyrolysis mechanisms derived from a common data set. A technical objective is to apply the most suitable derived kinetic parameters to model pyrolysis within a moving bed reactor. A novel fast pyrolysis micro-reactor is presented along with its design and development process. The micro-reactor allows for the control over both temperature and residence time of the reacting biomass. This system provides the experimental data for the characterization of biomass pyrolysis kinetic parameters. Thermal validation tests are presented and experimental yield results are given for raw Loblolly Pine, Avicel cellulose and Beechwood xylan for the derivation of kinetic descriptors. Cellulose and xylan results show good agreement with literature when the proper experimental conditions are met and whole wood pyrolysis results clearly demonstrate the dissimilarity between fast and slow pyrolysis apparent kinetic rates. The experimental results are then used to evaluate five different pyrolysis kinetic model configurations: single component global pyrolysis, two component global pyrolysis, product based pyrolysis, pseudo-component based pyrolysis and pseudo-component pyrolysis with an intermediate solid compound. Pseudo-component models are of particular interest because they may provide a generalized model, parameterized by the fractional composition of cellulose, hemicellulose and lignin in biomass species. Lignin pyrolysis yields are calculated to evaluate the suitability of a pseudo-component parallel non-competing superposition pyrolysis model. Lignin yields are estimated by taking the difference between whole wood pyrolysis and predicted cellulose and hemicellulose pyrolysis behaviors. The five models are then evaluated by comparison of predicted yields to the results for the pyrolysis of Scots pine (Pinus sylvestris) and Norway spruce (Picea abies). Model evaluations show that pseudo-component superposition is not suitable as a generic pyrolysis model for the fast pyrolysis of biomass observed using the micro-reactor. Further analytical evaluations indicate that the assumption of parallel non-competing reactions between pseudo-components is not valid. Among the other models investigated the intermediate solid compound model showed the best fit to the verification experimentation results followed closely by the two component global model. Finally, the derived kinetic parameters are applied to the design of moving bed vacuum pyrolysis reactors which provide for the separation of heat and mass transfer pathways, resulting in the reduction of char entrainment and secondary reactions within collected bio-oils. Reaction kinetics and porous bed heat and mass transfer are accounted for within the bed model. Model development and predictive results are presented and sensitivity to activation energy variations investigated.
112

Identification, isolation, expression analysis and molecular characterization of nine genes key to late embryogenesis in Loblolly pine

Jones, Brande 22 January 2011 (has links)
A basic understanding of the molecular events occurring during zygotic embryogenesis is required to fully understand how and why only a very small percentage of somatic embryos develop past the late embryogeny phase of embryogenesis. In this work, we have identified genes that have been demonstrated to be required for late embryonic development in the model plant system Arabidopsis thaliana. These genes were subsequently isolated and cloned from Loblolly pine embryos. These isolated clones were sequenced and analyzed to reveal significant homology to the known Arabidopsis ABA responsive genes ABI3, ABI4, and ABI5. Expression analyses of all three genes were completed, and compared to reported data of ABA accumulation, as well as, expression of other ABA responsive genes during the same stages of embryogenesis. Six putative root development genes were isolated and cloned from Loblolly pine embryos. These isolated clones were sequenced and analyzed to reveal significant homology to the known Arabidopsis root development genes WOODENLEG, SHORT ROOT, SCARECROW, HOBBIT, BODENLOS, and MONOPTEROS. Full-length cDNAs were isolated and cloned for WOODENLEG, SHORT ROOT, SCARECROW and BODENLOS. Expression analyses of all six genes were completed throughout mid to late embryogenesis in Loblolly pine.
113

Selenium redox cycling isolation and characterization of a stimulatory component from tissue of loblolly pine for multiplication of somatic embryos; development of an assay to measure l-phenylalanine concentration in blood plasma /

DeSilva, Veronica January 2007 (has links)
Thesis (Ph.D)--Chemistry and Biochemistry, Georgia Institute of Technology, 2007. / Committee Chair: Sheldon May; Committee Members: Nicholas Hud, Stanley Pollock, James Powers, and Gerald Pullman. Part of the SMARTech Electronic Thesis and Dissertation Collection.
114

The investigation of peracetic acid-oxidized loblolly pine by pyrolysis-gas chromatography-mass spectrometry

Fleck, John A. January 1975 (has links) (PDF)
Thesis (Ph. D.)--Institute of Paper Chemistry, 1975. / Includes bibliographical references (p. 94-100).
115

Correlation of certain morphological and hydrodynamic aspects of loblolly pine bleached kraft pulp

Binotto, Anthony P. January 1977 (has links) (PDF)
Thesis (Ph. D.)--Institute of Paper Chemistry, 1977. / Includes bibliographical references (p. 100-102).
116

A comparison of the B-lectins from Douglas-fir and loblolly pine during growth from seed to sapling

Bobalek, John Francis, January 1982 (has links) (PDF)
Thesis (Ph. D.)--Institute of Paper Chemistry, 1982. / Includes bibliographical references (p. 104-108).
117

The presence and metabolism of adenosine 3', 5'-cyclic monophosphate in loblolly pine (Pinus taeda) callus

Smeltzer, Richard H., January 1975 (has links) (PDF)
Thesis (Ph. D.)--Institute of Paper Chemistry, 1975. / Bibliography: leaves 98-104.
118

Ozone Damage Potential to Loblolly Pine Ecosystems in Metropolitan Atlanta, Georgia

Styers, Diane Marie 20 May 2005 (has links)
Atlanta is one of the largest metropolitan areas in the southeastern United States and is the only area in the region currently listed in “serious” 1-hour ozone nonattainment. Despite its exceedance history, impacts on Atlanta’s urban forests have not been the focus of any major studies. The purpose of this study was to examine air pollution damage to vegetation using a foliar-injury survey on Stone Mountain. The objectives of this project included 1) establishing that pollution transport from Atlanta to Stone Mountain occurs, 2) determining the magnitude of ozone concentrations near Stone Mountain and 3) assessing sensitive plant species on Stone Mountain for foliar injury. Results from this study confirm that Stone Mountain is located downwind from Atlanta. Ozone concentrations were sufficiently high to damage vegetation and these consistently peaked in July. Foliar injury was present on understory species on Stone Mountain, but was not observed on loblolly pine species.
119

The evaluation of novel anti-inflammatory compounds in cell culture and experimental arthritis and identification of an inhibitor to early-stage loblolly pine somatic embryo growth

Lucrezi, Jacob 12 January 2015 (has links)
The interactions between the immune and nervous systems play an important role in immune and inflammatory conditions. Substance P (SP), the unidecapeptide RPKPQQFFGLM-NH2, is known to upregulate the production of pro-inflammatory cytokines such as tumor necrosis factor (TNF)-α. We report here that 5 (Acetylamino) 4 oxo-6-phenyl-2-hexenoic acid methyl ester (AOPHA-Me) and 4 phenyl 3 butenoic acid (PBA), two anti-inflammatory compounds developed in our laboratory, reduce SP stimulated TNF-α expression in RAW 264.7 macrophages. We also show that AOPHA Me and PBA both inhibit SP stimulated phosphorylation of JNK and p38 MAPK. Furthermore, molecular modeling studies indicate that both AOPHA Me and PBA dock at the ATP binding site of apoptosis signal regulating kinase 1 (ASK1) with predicted docking energies of -7.0 kcal/mol and 5.9 kcal/mol, respectively; this binding overlaps with that of staurosporine, a known inhibitor of ASK1. Taken together, these findings support the conclusion that AOPHA Me and PBA inhibition of TNF-α expression in SP-stimulated RAW 264.7 macrophages is a consequence of the inhibition JNK and p38 MAPK phosphorylation. We have previously shown that AOPHA-Me and PBA inhibit the amidative bioactivation of SP, which also would be expected to decrease formation of pro-inflammatory cytokines. It is conceivable that this dual action of inhibiting amidation and MAPK phosphorylation may be of some advantage in enhancing the anti-inflammatory activity of a therapeutic molecule. We also encapsulated AOPHA-Me separately in polyketal and poly(lactic co glycolic acid) microparticles. The in-vitro release profiles of AOPHA-Me from these particles were characterized. We have also shown that AOPHA-Me, when encapsulated in PCADK microparticles, is an effective treatment for edema induced by adjuvant arthritis in rats. In separate work, it was determined that myo inositol 1,2,3,4,5,6 hexakisphosphate is an inhibitor to early-stage Loblolly pine somatic embryo growth. In addition, it was determined that muco inositol 1,2,3,4,5,6 hexakisphosphate is not an inhibitor to early-stage Loblolly pine somatic embryo growth. These experiments demonstrate the stereochemical dependence of myo inositol 1,2,3,4,5,6 hexakisphosphates inhibitory activity.
120

An Evaluation of Disturbance-Induced Nutrient Changes and Climate Responses of Loblolly Pine Xylem

Stratton, Rebecca Lynne 01 December 2011 (has links)
Dendrochronological techniques are currently limited to the identification of visible fire scars. However, through the development of new dendrochemical techniques, the potential exists to provide insight into a broader array of pyric ecosystems. In addition, the ability to identify historic climate-growth responses provides a better understanding of the conditions under which historic fire regimes occurred. This study provides the groundwork for the identification of a dendrochemical nutrient fire signature in xylem and identifies the climate-radial growth responses of loblolly pine (Pinus taeda L.) on five sites in the Piedmont of South Carolina. Changes in N, P, K, Ca, Mg, Zn, Cu, Mn, Fe, S, and Na concentrations in xylem as a result of a single fire were examined. The influences of monthly mean temperature, monthly total precipitation, Palmer Drought Severity Index (PDSI), Palmer Hydrological Drought Index (PHDI), and selected ocean-atmospheric oscillations such as El Nino-Southern Oscillation (ENSO), North Atlantic Oscillation (NAO), Pacific Decadal Oscillation (PDO), and Southern Oscillation Index (SOI) on radial growth using univariate and multivariate techniques were also assessed. Soil and duff analyses indicated sites were similar, but nutrient poor. Xylem mobile and immobile nutrient concentration analyses differed significantly through time for N, P, K, Ca, Mg, Zn, Cu, Mn, and S. No interactions were significant, thus identification of a nutrient fire signature was unsuccessful. The lack of significant interactions is attributed to the methodology used to collect the xylem nutrient samples; however, immobile nutrients indicate the most potential for future research. Climate-tree growth analyses indicate climate plays a role in the growth of mature loblolly pine in the South Carolina Piedmont. Temperature, precipitation, PDSI, positive phase NAO, and positive phase PDO are the primary drivers of loblolly pine radial growth. Temporal consistency results suggest drought sensitivity increases with tree age. Unlike the climate variables, the relationships between ocean-atmospheric oscillations and radial growth appear to be more cyclical in nature and only influence growth in positive phases.

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