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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.
471

Analýza složení a degradace léčivých látek a léčivých přípravků z 18. a 20. století / Analysis of the composition and degradation of pharmaceutical substances and pharmaceutical preparations from the 18th and 20th centuries

Kudláček, Karel January 2021 (has links)
The dissertation focused on the analysis of twenty historical remains of pharmaceutical substances and pharmaceutical preparations dating to the 18th and 20th century by liquid and gas chromatography with UV-spectrometric or mass spectrometric detection. The analytical approach was chosen with regards to the age and pharmaceutical forms of the analyzed historical remain. The authenticity of the sample was verified by identifying the active ingredients, their possible degradation products and other excipients by tandem mass spectrometry. The fragmentation of some analytes was also studied by tandem mass spectrometry. The stability of historical pharmaceutical preparations from the 20th century was assessed on the basis of a decrease in the concentration of active substances compared to the content declared by the manufacturer or, in case of historical pharmaceutical remains from the 18th century, on the basis of active substance concentrations determined in the historical residue and current reference material. A multi-analytical approach combining five analytical methods, the results of which complement each other, was used to analyze the historical remains of ointments. While the active substances identified in ipecacuanha were found to be partially degraded, they were completely degraded in senna...
472

Development of a rapid and in-field phenotyping tool for screening protein quality in soybeans (Glycine max) using a miniature near infrared sensor

Sia, Xin Rong January 2019 (has links)
No description available.
473

Effect of Enrichment-Bleaching and Low Oxygen Atmosphere Storage on All-Purpose Wheat Flour Quality

Swindler, Jonathan Myers 14 June 2013 (has links) (PDF)
All-purpose wheat flour is a useful long-term storage commodity, but is subject to off-odor formation. Although flour stored in a low oxygen atmosphere should inhibit rancid odor formation, it elicits consumer complaints about odor. The purpose of this study was to examine off-odor development in all-purpose wheat flour during ambient and elevated storage by determining the effect of low oxygen atmosphere and enrichment-bleaching on quality as measured by, free fatty acids (FFA), flour descriptive sensory analysis, conjugated dienes, headspace volatiles, bread consumer sensory analysis, color, loaf volume, and vitamin analysis. Enriched, bleached (EB) and unenriched, unbleached (UU) flour was stored in a low and normal oxygen atmosphere in no. 10 cans at 22, 30, and 40°C for 24 weeks. Moisture remained constant throughout the study. Headspace oxygen was < 0.1% in flour stored in a low oxygen atmosphere and decreased in flour stored in a normal oxygen atmosphere. FFA increased with storage time and temperature. The "fresh flour" descriptive aroma of flour decreased during storage and decreased more rapidly in a low oxygen atmosphere. The "cardboard/stale" aroma increased in flour stored in a normal oxygen atmosphere. The "acid-metallic" aroma increased in flour stored in a low oxygen atmosphere and was determined to be the off-odor from consumer complaints. Conjugated dienes and volatiles generally increased more rapidly in flour stored in a normal oxygen atmosphere and in EB flour, suggesting that the acid-metallic odor did not result from lipid oxidation. Bread consumer sensory analysis identified EB flour stored in a normal oxygen atmosphere to have the lowest acceptance scores for aroma, overall acceptability, and flavor. The acid-metallic odor dissipated within 24 hours when the container was opened and was not detrimental to consumer acceptance of bread made from the flour. Oxygen absorbers prevented the darkening of flour but not the reddening or yellowing. A low oxygen atmosphere resulted in higher bread loaf volumes. Vitamin degradation is not a concern under normal storage conditions. Bleaching appears to increase flour oxidative rancidity more than enrichment. Although storage at a low oxygen atmosphere results in an off-odor present in newly opened cans, it gave higher quality flour and bread. A low oxygen atmosphere should continue to be used in flour stored long-term, and consumers should be made aware that the off-odor present in cans of flour dissipates after opening.
474

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.
475

The development of cellular metabolomic platforms and their applications

Fei, Fan January 2016 (has links)
In this thesis, an analytical platform was designed and applied to various in vitro bacterial and eukaryotic cell cultures. An extraction and an analytical protocol were developed for comprehensive and simultaneous analysis of both lipid and polar metabolites for intra- and extracellular metabolomics using HILIC-LC-TOF-MS. This analytical platform was applied to four diverse research questions such as the effect of oxygen environment on growth, the interplay between gene expression and metabolism, metabolic changes that occur with age, and PAH toxicity. Specifically: (i) the effect of oxygen on the growth, physiology and metabolism of the Gram positive Streptococcus intermedius were investigated by comprehensive intra- and extracellular metabolomes and transcriptome. (ii) Metabolic insights into the role of the multipartite genome of the Gram negative bacteria Sinorhizobium meliloti and its metabolic preferences in a nutritionally complex environment. (iii) Age-associated metabolic dysregulation in murine bone marrow-derived macrophages during bacterial lipopolysaccharide-induced inflammation. (iv) Comprehensive intracellular metabolomic profiles of Sinorhizobium meliloti to sub-lethal exposure of individual or mixtures of polycyclic aromatic hydrocarbon revealed additive and dose-dependent effects. This thesis has demonstrated the versatility of the designed analytical platform and its use for diverse research in cell biology. / Thesis / Doctor of Philosophy (PhD)
476

Beyond the vessel: Organic residue analysis of Late Bronze and Early Iron Age south-east European pottery

Bastos, Beatriz I.F. de January 2019 (has links)
The Encounters and Transformations in Iron Age Europe project (ENTRANS) aims to expand our knowledge regarding the nature and impact of cultural encounters during the European Iron Age. The study of ceramic vessels was included in the project, in order to further understand cultural practices in the south-east Alpine region. Organic residue analysis is an important tool in archaeological research for determining the presence of food and other organic substances associated with ceramic vessels. It has the potential to significantly improve our understanding of Iron Age societies and the interactions between them. This research focuses on the analysis of visible and absorbed organic residues from 377 ceramic vessels, from Late Bronze Age and Early Iron Age sites in Slovenia and Croatia, by gas-chromatography mass spectrometry. Two methods of lipid extraction were compared in a pilot study compressing 30 potsherds from Kaptol (solvent vs. acid extraction). This study revealed that more information was obtained by acid extraction, thus it was selected as the main method of extraction for this project. Differences between settlement, funerary and ritual sites were observed, suggesting that the vessels placed in the graves were not previously used or carried foodstuff with low lipid content, such as liquids and dry foods/cereals. Some types of residues were only identified in funerary vessels, specifically potential castor oil in Kaptol, mixed with other fats and oils. Lipid biomarkers and lipid ratios revealed significant differences between contexts and different sites, suggesting that the differences in cultural practices can also be identified in the use of ceramic vessels. Some residues were also sampled for gas-chromatography compound-specific isotope ratio mass spectrometry and bulk isotope analysis (only visible residues), which identified potential dairy fats in two potsherds from Poštela. The results were also compared with the contextual information, mainly the faunal remains, and the data obtained from the osteology and diet study preformed with individuals from the same area and chronology as the ceramic vessels. / Encounters and Transformations in Iron Age Europe Project (ENTRANS); Humanities in the European Research Area (HERA); Institute Life Sciences Research (ILSR) University of Bradford.
477

Polybrominated Diphenyl Ethers: Soil Sorption and Microbial Degradation

WELSH, GWENDOLYN L. 23 September 2008 (has links)
No description available.
478

Carbon and nitrogen distribution and processes in forest and agricultural ecosystems: a study involving solid- and liquid-state NMR and pyrolysis GC/MS

Dria, Karl Jay 17 June 2004 (has links)
No description available.
479

USE OF MICROALGAE FOR WASTEWATER TREATMENT AND BIOFUEL PRODUCTION: EFFECTS OF ENVIRONMENTAL CONTAMINANTS ON THE CELLULAR RESPONSE

Ranjbar Kolachaie, Sibia January 2015 (has links)
Microalga-based technologies are introduced to provide a new generation of biofuels. The cultivation of microalgae in wastewater as the growth medium may offer the dual benefit of wastewater treatment and sustainable biofuel production. The potential of microalgal biomass to be converted into biodiesel depends on the accumulation of lipids, mainly triacylglycerols. However, the presence of toxic contaminants in municipal or industrial wastewater could negatively affect the biomass growth and modify the pattern of lipid accumulation in algae cells. This research aims to evaluate the potential of cultivating microalgae in wastewater for the removal of selected contaminants and the production of biodiesel. The hypothesis underlying this work was that growing microalgae in the presence of contaminants, typically found in wastewater, may induce a stress response that potentially increases the lipid productivity and enhances the biofuel yield. This research explored the potential of microalgae to be used for the removal of wastewater pollutants while accumulating high concentrations of neutral lipid that can be converted into biodiesel. Physiological and transcriptional responses of two genera of green algae were observed in the presence of stresses induced by toxic metals in raw hydraulic fracturing flowback water and pharmaceuticals found in municipal wastewater. Two green algae, Dunaliella salina and Chlorella vulgaris, were selected based on the availability of genetic information, current trends in the alga industry, and specific growth requirement in hypersaline flowback water and municipal wastewater. The first part of this research focuses on the possibility of using the salt-tolerant green microalga, D. salina, for the removal of toxic metals from hydraulic fracturing flowback water. In the second part of this research, the freshwater green microalga, C. vulgaris, was exposed to a suite of pharmaceuticals, commonly found in municipal wastewater, and the effects on the biomass growth and lipid accumulation were evaluated. In Chapter 3, aqueous geochemical characteristics of hydraulic fracturing flowback water were determined. Metagenomic analysis was also used to characterize the microbial community structure of the water samples. This technique included DNA extraction, PCR amplification of genes for 16S and 18S ribosomal RNA, and pyrosequencing. Although the two flowback water samples were shown to have water property measures in the range of reported values in literature, they were significantly different from each other regarding water properties such as total dissolved solids and total organic carbon. They also had distinct microbial community structures. It was shown the flowback water samples contained mainly halophilic, anaerobic, and thermophilic species with a pattern that was expected to be seen in natural gas shale reservoirs. Chapter 4 covers the characterization of the effects of contaminants (toxic metals) in hydraulic fracturing flowback water on the biomass growth and cellular lipid accumulation in Dunaliella salina. Metals were analyzed using ICP-MS. Biomass accumulation was determined by spectrophotometry and gravimetric methods. Lipid accumulation and composition were determined by GC-MS after conversion into fatty acid methyl esters. D. salina was successfully cultivated in saline hydraulic fracturing flowback water, and algal biomass growth was associated with a significant reduction of several toxic metals in the samples. D. salina, grown in flowback water, accumulated high levels of cellular lipids. Also, the estimated biodiesel properties were comparable with other algal biodiesel and complied with the US and EU biodiesel standards. The last chapter of part one presents the effects of a collection of metals commonly found in hydraulic fracturing flowback water and other industrial wastewaters on growth and lipid accumulation of D. salina. The impacts of the nitrogen concentration in the growth medium were also observed. The Nile red assay (fluorescence measurement after Nile red staining) was used to assess lipid accumulation. A range of toxic effects on the algal growth was observed. However, the effects were lower at higher nitrogen level that may indicate to an improved toxicity resistance when nutrient stress is minimal. Even with a high dose-dependent toxicity on growth, some toxic metals increased lipid accumulation. Chapter 6 describes the microplate-based toxicity test conducted to characterize the effect of a range of emerging contaminants (pharmaceuticals) commonly found in municipal wastewater on the biomass growth and cellular lipid accumulation measured by Nile red staining assay. Similar to what was observed for metals in Chapter 5, some pharmaceuticals increased lipid accumulation, even with a high dose-dependent toxicity on algal growth. Most tested pharmaceuticals at municipal wastewater levels (low) did not have a significant effect on the algal growth and lipid accumulation. Toxicity data (EC50 of growth) were well in agreement with what was reported in literature and antibiotics were the most toxic compounds among the different pharmaceutical classes. Chapter 7 presents a further characterization of the effects of a few selected compound from the previous chapter. Changes in the algal lipid composition upon exposure to the selected compounds were determined by qualitative and quantitative analysis of the extracted lipids using GC-MS. FT-IR spectroscopy was used to detect changes in the cellular constituents. The transcriptional responses of the key genes involved in the lipid metabolism of C. vulgaris were also investigated upon exposure to tetracycline using reverse-transcription real-time PCR and the results were interpreted based on the measured levels of cellular lipids and other metabolites. Lipid accumulation was changed upon exposure of algae to pharmaceuticals; however, the FAMEs profile did not show a significant variation. FT-IR spectroscopy highlighted the subtle changes in the cellular basis, and FT-IR peak associated with lipids was strongly correlated with total FAMEs quantified by GC-MS (Pearson correlation coefficient = 0.89). Gene expression analysis showed a general down-regulation of genes involved in the lipid biosynthesis. Results from this research are expecting to help develop and optimize innovative algal-based technologies combining the benefits of wastewater treatment, sustainable biofuel production, and mitigation of carbon dioxide emissions. / Civil Engineering
480

From Susa to Anuradhapura: Reconstructing aspects of trade and exchange in bitumen-coated ceramic vessels between Iran and Sri Lanka from the Third to the Ninth Centuries AD.

Stern, Ben, Connan, J., Blakelock, Eleanor S., Jackman, R., Coningham, Robin A.E., Heron, Carl P. January 2008 (has links)
No / In contrast with artefactual studies of long-distance trade and exchange in South Asia during the Prehistoric and Early Historic periods (Ardika et al . 1993; Gogte 1997; Krishnan and Coningham 1997; Tomber 2000; Gupta et al . 2001; Ford et al . 2005), few scientifically orientated analyses have focused on artefacts from the region¿s Historic period. During excavations at the ancient city of Anuradhapura, Sri Lanka, a number of buff ware ceramics with a putative organic coating on the interior were recovered (Coningham 2006). Dated stylistically to between the third and ninth centuries AD , analysis of the coatings using gas chromatography¿mass spectrometry (GC¿MS) and stable isotope analysis (carbon and deuterium) confirmed that the coatings are bitumen¿an organic product associated with petroleum deposits. There are no known bitumen sources in Sri Lanka, and biomarker distributions and isotopic signatures suggest that the majority of the samples appear to have come from a single bitumen source near Susa in Iran. The relationship between the bitumen coatings and the vessels is discussed, and it is suggested that the coatings were used to seal permeable ceramic containers to allow them to transport liquid commodities. This study enhances our knowledge of networks of trade and exchange between Sri Lanka and western Asia during Historic times.

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