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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.
1

Selected anatomical, extractive and physical wood properties of Cylicodiscus gabunensis (Harm) : a tropical timber species /

Boakye-Yiadom, Kaleem, January 2001 (has links)
Thesis (Ph. D.)--University of Missouri-Columbia, 2001. / Typescript. Vita. Includes bibliographical references (leaves 135-145). Also available on the Internet.
2

Selected anatomical, extractive and physical wood properties of Cylicodiscus gabunensis (Harm) a tropical timber species /

Boakye-Yiadom, Kaleem, January 2001 (has links)
Thesis (Ph. D.)--University of Missouri-Columbia, 2001. / Typescript. Vita. Includes bibliographical references (leaves 135-145). Also available on the Internet.
3

Approche analytique et expérimentale pour la caractérisation des exsudats et goudrons de plantes archéologiques : préhistoire, ethno-archéologie et chimie / Analytical and experimental approach for the characterization of archaeological plant exudates and tars : prehistory, ethno-archaeology and chemistry

Delgado Robles, Alma Angelina 10 December 2018 (has links)
Parmi les matériaux qui ont été exploités dans l'Antiquité, les substances organiques sont probablement les plus difficiles à étudier en raison de leur altération partielle ou totale en raison de leur nature organique. Issus de biomatériaux organiques tels que les résines, la cire d'abeille, les graisses animales ou les huiles végétales, ils sont conservés en faible quantité comme résidus organiques amorphes et sont souvent difficiles à détecter sur le terrain archéologique. Ils témoignent de l'utilisation de produits d'origine animale, végétale et fossile qui ont une grande importance pour divers aspects de la vie humaine, notamment l'alimentation, la médecine, les rituels funéraires, ainsi que les activités économiques et techniques. Comme ils n'ont pas d'attributs morphologiques reconnaissables, la seule façon de déterminer leur nature et leur origine repose sur l'élaboration de stratégies analytiques qui permettent d'élucider leur composition chimique. Ces substances ont des caractéristiques communes dans le domaine de l'archéologie et de la chimie : elles sont constituées de mélanges moléculaires complexes qui sont souvent conservés en faible quantité. Dans certains cas, ces matériaux ont été mélangés avec divers adjuvants tels que la cire d'abeille, les huiles végétales, les graisses animales, l'argile et l'ocre, entre autres, qui devront également être pris en considération pour la caractérisation des objets qui appartiennent au patrimoine culturel. Nous concentrons nos recherches sur les exsudats et les goudrons de plantes frais et fossiles qui ont été largement utilisés depuis la préhistoire en Europe. Concernant l'étude des substances organiques fraîches, des recherches ethnoarchéologiques ont été menées en collaboration avec le projet ONGUENT (Goudrons végétaux à usage médicinal en Méditerranée : passés et présents. Burri, Sylvain/Traces, Toulouse) afin d'identifier et de caractériser la composition chimique et d'établir les biomarqueurs des goudrons de conifères ethnoarchéologiques de Cupressaceae et Taxaceae (Juniperus oxycedrus, Juniperus thurifera, Taxus baccata, Tetraclinis articulata) provenant de techniques anciennes du Haut Atlas au Maroc. En comprenant les méthodes de fabrication des échantillons ethnoarchéologiques et en évaluant les différentes techniques employées dans leur production, il est possible d'obtenir des données de référence sur les matériaux contemporains. D'autre part, des échantillons archéologiques ont été analysés sur différents sites entre l'Europe et l'Asie au moyen des méthodes FTIR, SEM, DI-MS, et GC-MS. La caractérisation biomoléculaire de produits naturels tels que le goudron d'écorce de bouleau et la résine de pin a été soulevée. Par ailleurs, des mélanges de résine de pin avec du goudron d'écorce de bouleau et de résine de pin avec une espèce appartenant à la famille des Burseraceae ont été identifiés. / Among the materials that have been exploited in ancient periods, organic substances are probably the most challenging to study due to their partial or total alteration in consequence of their organic nature. Issued from organic biomaterials such as resins, beeswax, animal fats or plant oils, they are preserved in low amount as amorphous organic residues and are often difficult to detect at the archaeological field. They give evidence for the use of animal, plant and fossil products that were of great importance for various aspects of human life, including diet, medicine, funerary rituals, as well as economic and technical activities. Because they lack recognizable morphological attributes, the only way to determine their nature and origin relies on the development of analytical strategies that allow elucidation of their chemical composition. These substances share common features in the field of archaeology and chemistry: they are made of complex molecular mixtures which are often preserved at low amount. In some cases, these materials were mixed with various adjuvants such as beeswax, plant oils, animal fats, clay, and ochre, among others, that will also need to be considered for the characterization of the objects that belong to the Cultural Heritage. We focus our research on fresh and fossil plant exudates and tars that have been largely used since prehistory onwards in Europe. Concerning the study of fresh organic substances, ethnoarchaeological research has been carried out in collaboration with the ONGUENT project (Goudrons végétaux à usage médicinal en Méditerranée: passés et présents. Burri, Sylvain/Traces, Toulouse) in order to identify and characterize the chemical composition and establishing the biomarkers of the ethnoarchaeological conifer tars from Cupressaceae and Taxaceae (Juniperus oxycedrus, Juniperus thurifera, Taxus baccata, Tetraclinis articulata) obtained from antique techniques in the High Atlas, Morocco. By understanding the manufacturing methods of ethnoarcheological samples and to assess the different techniques employed in their production, it is possible to obtain a reference data on contemporary materials.On the other hand, archaeological samples were analyzed from different sites between Europe and Asia by means of FTIR, SEM, DI-MS, and GC-MS methods. Biomolecular characterization of natural products such as birch bark tar and pine resin were raised. Besides, mixtures between pine resin with birch bark tar and pine resin with a species belonging to the family of Burseraceae were identified.
4

The effects of various root exudates on broomrape germination

Ballard, Barbara Jean January 1979 (has links)
no abstract provided by author / Master of Science
5

Studies on secretion and absorption in Dionaea muscipula Ellis

Robins, Richard J. January 1978 (has links)
The ultrastructure and physiology of the secretory glands of Dionaea muscipula Ellis (The Venus's Flytrap) have been examined in order to investigate the mechanism of obtaining nutrients practised by this plant. The dynamic changes in the ultrastructure following stimulation have been examined. Particularly prominent features are a decrease in the size of the main cell vacuole and an increase in smaller vacuoles. Important changes are also observed in the distribution of ribosomes within the secretory cells. By the use of high resolution histochemical, cytochemical, and autoradiographic methods, it is shown that the secretory hydrolases are probably stored in a sub-compartment of the vacuole, the smooth endoplasmic reticulum and the cell walls. It is shown by quantification of the cell and by autoradiography that the dictyosomes do not appear to be involved in the discharge of secretion, but rather that this probably occurs both by direct fusion of the endoplasmic reticulum with the plasmalemma and by the migration of vesicles derived from the endoplasmic reticulum directly to the cell periphery. Evidence is presented to show that, in addition to being released from a site of storage, some of the protein discharged is synthesized de novo during the cycle. This is suggested by the observed formation of numerous polysomes associated with the endoplasmic reticulum in the secretory cells and confirmed by radiolabelling techniques. A preliminary analysis of the enzymology of the secretion is presented and it is tentatively suggested that there are several peptide hydrolase activities present, possibly including a serine proteinase and a carboxypeptidase. It is shown that the secretion can hydrolyse chitin and has peroxidase activity. By following the absorption of chloride ions, it is shown that the plasmodesmata are important in the uptake of these ions. The overall architecture of the gland is considered in relation to the possible pathway of absorption of digestive products and it is suggested that the plasmo-desmata are probably the primary route for the movement of nutrients into the glands. A model is put forward, based on these observations, for the way in which the gland conducts a bi-directional flow of material. It is hypothesized that, while absorption takes place via the symplast, secretory proteins are discharged directly into the apoplast and flushed from there by hydrostatic pressure generated by the inner secretory cells. Suggestions are made for how this might be achieved.
6

Guar and locust bean gums as partial replacers of all-purpose flour in bread : an objective and sensory evaluation /

Schwarzlaff, Sabine Susanne, January 1993 (has links)
Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1993. / Includes bibliographical references (leaves 84-91). Also available via the Internet.
7

Guar and locust bean gums as partial replacers of all-purpose flour in bread: an objective and sensory evaluation

Schwarzlaff, Sabine S. 10 November 2009 (has links)
The purpose of this research was to determine whether all-purpose flour could be partially replaced with locust bean gum (LBG) and guar gum, and produce an acceptable bread product. A pilot study determined that up to 4% gum replacement for flour was feasible. All bread treatments were evaluated objectively by standing height, texture, color, and cell size. Moisture determinations were obtained for each bread variation. Sensory quality was examined by consumer testing. The amount of heat required to break the hydrogen bonds in amylopectin, indicative of bread staling, was measured by differential scanning calorimetry (DSC) for all bread treatments. Two percent LBG replacement significantly increased standing height. Firmness of bread increased with an increase in gum; the 4% guar bread was significantly firmer. Crumb color was not significantly different for any of the five bread treatments. Crust color, however, was significantly lighter for the control in comparison to the 2 and 4% guar, and 4% LBG breads. Two percent guar produced a more even cell size distribution throughout the bread crumb. For all 5 bread formulations moistures were not significantly different. Sensory evaluation determined a significant difference between the control and 4% LBG. The 4% LBG bread was preferred, although not significantly. Both gums were found to retard bread staling and 2% LBG was the most effective in lengthening the shelf life of the bread product. Objective and sensory evaluation indicated both gums produced acceptable bread products for consumer consumption and possible use in further research. / Master of Science
8

The final masquerade : a molecular-based approach to the identification of resinous plant exudates in Roman mortuary contexts in Britain and evaluation of their significance

Brettell, Rhea C. January 2016 (has links)
This study provides chemical confirmation for the use of resinous plant exudates in mortuary contexts in Roman Britain. Analysis of amorphous masses, adhering residues and grave deposits using gas chromatography-mass spectrometry has revealed terpenoid biomarkers in sixteen inhumation and two cremation burials. The natural products characterized include European Pinaceae (conifer) resins, Pistacia spp. (mastic/terebinth) resins from the Mediterranean or the Levant and Boswellia spp. (frankincense) gum-resins from southern Arabia or eastern Africa. In addition, traces of a balsamic resin, probably Liquidambar orientalis, have been identified. A correlation between the use of these exotic exudates and interment in substantial, often multiple, containers with high-quality textiles and grave goods was observed. Theoretical consideration of this imported rite illuminates the multiplicity of roles played by resins/gum-resins in the mortuary sphere. The material properties of these highly scented substances speak to the biological reality of the decomposing body and to the socially constructed identity of the individual. On a practical level, they acted as temporary preservatives and masked the odour of decay. As social signifiers, they denoted the status of the deceased and promoted remembrance through conspicuous consumption and sensory impact. Encoded with ritual meaning, they purified the body and facilitated the final rite of passage to the afterlife. The recovery of these resinous traces provides us with new insights into the treatment of the body in the Roman period and establishes fresh links between the remote province of Britannia and the remainder of the Empire.
9

The final masquerade: a molecular-based approach to the identification of resinous plant exudates in Roman mortuary contexts in Britain and evaluation of their significance

Brettell, Rhea C. January 2016 (has links)
This study provides chemical confirmation for the use of resinous plant exudates in mortuary contexts in Roman Britain. Analysis of amorphous masses, adhering residues and grave deposits using gas chromatography-mass spectrometry has revealed terpenoid biomarkers in sixteen inhumation and two cremation burials. The natural products characterized include European Pinaceae (conifer) resins, Pistacia spp. (mastic/terebinth) resins from the Mediterranean or the Levant and Boswellia spp. (frankincense) gum-resins from southern Arabia or eastern Africa. In addition, traces of a balsamic resin, probably Liquidambar orientalis, have been identified. A correlation between the use of these exotic exudates and interment in substantial, often multiple, containers with high-quality textiles and grave goods was observed. Theoretical consideration of this imported rite illuminates the multiplicity of roles played by resins/gum-resins in the mortuary sphere. The material properties of these highly scented substances speak to the biological reality of the decomposing body and to the socially constructed identity of the individual. On a practical level, they acted as temporary preservatives and masked the odour of decay. As social signifiers, they denoted the status of the deceased and promoted remembrance through conspicuous consumption and sensory impact. Encoded with ritual meaning, they purified the body and facilitated the final rite of passage to the afterlife. The recovery of these resinous traces provides us with new insights into the treatment of the body in the Roman period and establishes fresh links between the remote province of Britannia and the remainder of the Empire. / Arts and Humanities Research Council (AHRC). / Vol. II, which contains supplementary material files, is not available online.

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