This research is concerned with the mechanisms of diffusion in the Earth and the implications of such an understanding. Specifically, this work is concerned with one particular aspect of diffusion: Grain Boundary Diffusion (GBD). An experimental investigation of GBD has been conducted by considering three specific scenarios; GBD of H in stoichiometric Mg-spinel, GBD of Ti in Quartz and GBD of Li in olivine. By considering the GBD of three very different elements it has been possible to synthesise an understanding of some of the mechanisms involved in the process. GBD is potentially a very important process within the Earth with wide ranging implications. Grain boundaries may provide fast pathways for transportation of a range of compatible and incompatible diffusing species in the Earth’s interior – potentially acting as storage locations and also as efficient pathways between different geological reservoirs. It is also potentially very important in the application of a number of techniques including dating and geothermometry and geobarometry. Here, an experimental study of the GBD of H has been carried out with the overall finding that GBD appears to occur at slightly greater yet broadly similar rates to lattice diffusion. This finding is considered in terms of the mantle properties which are affected by the presence and transport of H. A follow up series of experiments was conducted looking at Li diffusion. Li was chosen due to its volatile nature and larger atomic radius as compared to H. As such, it provided a useful test of the hypothesis that the radius of a diffusant might affect its chosen method of diffusion. A third set of experiments were carried out to investigate the GBD of Ti in quartz with particular reference to the TitaniQ geothermo(baro)meter. This set of experiments provided a very useful comparison to the data which had previously been obtained from lighter elements. This investigation has found that a combination of factors including charge, diffusant diameter and the specific mineralogical characteristics of the host phase will define the dominant diffusive mechanism and the size of the contribution made by that mechanism towards observed bulk diffusivities. A characterisation of the temperature dependency of diffusion within each setting has also been completed. As such, it also makes a useful contribution to the current dataset for GBD.

The bulk of the eruption of Askja in north central Iceland on March 28-29 1875 consisted of a plinian eruption that lasted 6-7 hours, produced 0.2 km3 of ash and rhyolitic pumice, and created a surge and partially welded ash/pumice fall deposit that crops out on the shore of the modern caldera lake (Sparks et al. 1981). We evaluate the volatile budget of the magma during the eruption and focus on water concentration in glass fragments and shards, glass adjacent to crystals, and melt inclusions (MIs). Sparks et al. (1981) estimated the gas exit velocity at the vent was 380 m/s during the plinian phase, and the water concentration at 2.8 wt%. Measurements of water concentration in basaltic and rhyolitic glass shards from layers C through E range from 0.15 to 0.5 wt%, with variations within layers, a drop in layer D, and increase in layer E. Plagioclase and pyroxene crystals from layers C through E contain rhyolitic MIs with water concentrations ranging from 0.1 to 1.8 wt%, some higher than the matrix glass. Magma underwent degassing on its way to the surface. Rhyolitic glass adjacent to crystals hosting MIs has the highest water concentration, from 0.4 to 2.18 wt%. This, and the initial phreatoplinian eruptive style, both suggest interaction of magma with meteoric water during the eruption. Intimate mixtures of basaltic glass compositions within samples and basaltic glass surrounded by rhyolitic glass support the conclusion of Sigurdsson and Sparks (1981) that magmas mingled prior to and during the eruption.

There has been a lot of interest in Roselle (Hibiscus sabdariffa L.), called Bissap in Senegal, hibiscus recently because of consumer interest in nutraceutical products. However, beverages made from hibiscus have a short self-life due to anthocyanin and flavor degradation. The purpose of our study was first to assess the impacts of water, extraction procedure and origin on the anthocyanins of hibiscus extracts and secondly, to examine the impacts of freeze-drying on the anthocyanins and the volatiles compositions of hibiscus extracts. For the first experiment, a 2x3 factorial design was used with hibiscus calyces from Senegal and Egypt for the factor origin, distilled water and reformulated Dakar (Senegal) water for the second factor water, and then cold and hot extraction procedures were applied. For the second experiment, Senegalese hibiscus was extracted with hot and cold water and one part of each extract was freeze-dried. For both objectives, a ratio of 1:15 w/v (1 kilogram of calyces for 15 liters of water) were used. The time-temperature was 98°C / 30 min for hot and 22°C / 4 hours for cold extractions. The anthocyanins were determined using high performance liquid chromatography (HPLC). And the volatiles were measured using headspace-solid phase microextraction and gas chromatography-mass spectrometry (HS-SPME-GCMS). Origin and temperature as well as their interaction had significant effects on the anthocyanin contents, with respective p-values of 0.0036 and 0.0025 and 0.0002. Freeze-drying showed no effect on the anthocyanins in cold extracts. In contrast, a significant difference between the hot extract and its freeze-dried product was observed with a p-value of 0.0013. For the flavor compounds, the aroma profiles were different between cold and hot extracts and their instant powders. Globally the results of this study can help in the optimization when processing hibiscus derivatives. / MSLFS

In the first experiment, effects of brewing time, chlorine, chloramine, iron, copper, pH and water hardness were investigated for their effects on extraction of epigallocatechine gallate (EGCG) and caffeine in green tea and oolong tea aqueous infusions. The extraction of EGCG and caffeine were lower when green tea was brewed in hard water compared to distilled water. Brewing green tea and Oolong tea in tap water resulted in higher extraction of caffeine but had no effect on EGCG compared to distilled water. The extraction of EGCG and caffeine were significantly increased (P<0.05) when green tea and Oolong tea were brewed in the chlorinated water at 4.0 mg free chlorine per liter. The purpose of the second experiment was to optimize SDE conditions (solvent and time) and to compare SDE with SPME for the isolation of flavor compounds in Jin Xuan oolong tea using Gas Chromatography- Mass Spectrometry (GC-MS) and Gas Chromatography- Olfactrometry (GC-O). The concentration of volatile compounds isolated with diethyl ether was higher (P<0.05) than for dichloromethane and concentration was higher at 40 min (P<0.05) than 20 or 60 minutes. For SDE, 128 volatiles were identified using GC-MS and 45 aroma active compounds using GC-O. The number of volatiles identified using GC-MS was lower in SPME than SDE. For SPME, 59 volatiles and 41 aroma active compounds were identified. The composition of the volatiles isolated by the two methods differed considerably but provided complementary information. The goal of the third experiment was to determine effects of panning on flavor volatile compositions of oolong using GC-MS and GC-O. Simultaneous Distillation and Extraction (SDE) and Solid Phase Microextraction (SPME) techniques were applied for extraction of volatiles in panned and unpanned teas. A total of 190 volatiles were identified from SDE and SPME extractions using GC-MS and GC-O. Trans-nerolidol, 2- hexenal, benzaldehyde, indole, gernaiol, and benzenacetaldehyde contents were significantly decreased (P<0.05) by panning; however, panning increased (P<0.05) contents of linalool oxide, cis jasmone, methyl salicylate in oolong tea. Overall, panning significantly changes the volatile compositions of the tea and created new aroma active compounds. / Ph. D.

The use of the electronic nose in the wine industry is an emerging technology. Although electronic nose systems have been used in other industries as tools to monitor fruit maturity or quality control, the use of these systems for wine analysis has been debated. Many electronic nose sensor types exist, but have often been accused of primarily discriminating varying ethanol concentrations of wines as opposed to aroma and flavor volatiles. This study evaluated the use of a commercial conducting polymer electronic nose to evaluate wines while minimizing ethanol interference. The first study presented evaluated the discrimination ability of an electronic nose with use of an ethanol baseline prior to wine evaluation. This experiment also determined the optimal wine temperature for electronic nose analysis. A second study reviewed the ability of the electronic nose to discriminate Cabernet Sauvignon grape and wine volatiles based on a pre-fermentation cold soak treatment. The electronic nose was used to monitor volatile changes throughout a five day cold soak, and to discriminate differences in control versus cold soak wines. These results were compared with juice and wine analytical data, GC-MS evaluation of individual volatiles, and sensory analysis of the finished wines. It was found that discrimination of wines improved from 33% to 60% when using an ethanol baseline. Influence of the baseline was indicated by a drop in sensor response prior to wine evaluation. A 30°C sample temperature was chosen for wine analysis based on sensor response and adequate discrimination in canonical distributions. The electronic nose was found to discriminate grape volatiles in cold soak musts as shown in canonical distributions at a 95% significance level. PCA distributions of electronic nose data, chemistry data, and GC-MS data showed varying degrees of discrimination based on analysis. Electronic nose data often showed 100% of variation of samples accounted by PC1. Despite differences in treatment by ENose and analytical data, sensory results did not find a difference in control and cold soak wines. / Master of Science

Campi Flegrei is a large volcanic complex located west of the city of Naples, Italy. The area has been the site of volcanic activity for more than 60 ka and represents a potential volcanic hazard owing to the large local population. In this study, the geochemistry of the magma associated with two different eruptions at Campi Flegrei has been characterized, with the aim to identify geochemical trends that may help to predict the style and nature of future eruptions. Two eruptions of different age and eruptive style have been selected for study, Fondo Riccio (9.5 ka) and Minopoli 1 (11.1 ka). A scoria (CF-FR-C1) and a bomb (CF-FR-C2) were collected from the Fondo Riccio eruption, and two scoria samples were collected from Minopoli 1 (CF-Mi1-C1 and C2) eruption. The pre-eruptive volatile content of magma plays an important role in the style of eruption and can be assessed from studies of melt inclusions (MI) contained in phenocrysts. Major and trace elements in Fondo Riccio MI show a wider variation compared to those in Minopoli 1 MI suggesting that the Fondo Riccio magma residence time was longer compared to the Minopoli 1 magma. Analyses of volatile contents in MI suggest that Fondo Riccio magma may have been more water-rich than Minopoli 1 magma, consistent with the more explosive character of this eruption compared to Minopoli 1. Trace element data suggest a combination of arc volcanic and upper continental crust magma as the source for the Fondo Riccio and Minopoli 1 eruptions. / Master of Science

Viognier (Vitis vinifera L.) grapes were grown in Northern Virginia for three seasons using three different training systems in a randomized complete block design consisting of Vertical Shoot Positioned (VSP), Smart Dyson (SD), and Geneva Double Curtain (GDC), and evaluated for the effects on grape and wine glycosides and volatile compounds. Fruit was harvested at the same Brix each season, and differences in berry weights were not observed. VSP-trained vines had the lowest crop load and lowest light levels in the fruit zone. Seventeen volatile compounds were analyzed using headspace solid-phase microextraction, GC-MS. Fruit showed differences in linalool, á-terpineol, â-damascenone, and n-hexanol concentrations among the training systems. Wines showed differences in both grape-derived and fermentation-derived volatiles. SD had the highest concentration for most of the free volatiles quantified in both the juice and wine. VSP had lower phenol-free wine glycosides all three seasons and lower phenol-free juice glycosides one season. Triangle difference sensory testing demonstrated differences between GDC and SD in wine aroma and flavor, and differences between VSP and SD in flavor, for two of three seasons. / Master of Science

La rose est l'une des plantes ornementales les plus populaires, dont les composés volatils sont non seulement impliqués dans les interactions des fleurs avec l’environnement au sens large, mais aussi largement utilisés dans l’industrie des arômes et parfums. Le chapitre 1 décrit l'histoire de la culture de la rose, les usages de son parfum, les connaissances actuelles sur la biosynthèse des composés de ce parfum, ainsi que les voies de biosynthèse des composés volatils qui ont été récemment élucidées chez différentes plantes. Les chapitres expérimentaux 2 et 3 analysent les fonctions de deux gènes exprimés dans les pétales de rose. Ils codent pour des protéines Nudix hydrolase 1 (NUDX1). Le gène NUDX1-1 (nommé RhNUDX1 dans la publication) a été découvert en comparant les transcriptomes de deux cultivars de rose, Rosa x hybrida cv. 'Papa Meilland' (PM) très parfumé et R. x hybrida cv. 'Rouge Meilland' (RM), dépourvu de parfum. Le gène RhNUDX1-1 n'est exprimé que chez PM et son expression est corrélée avec la production de monoterpènes dans les pétales, en particulier de géraniol. Lors de l'étude d'une descendance issue du croisement de R. chinensis cv. ‘Old Blush’ (OB) et de R. x wichurana (Rw), le gène orthologue RcNUDX1-1a, présentant la même fonction, a été caractérisé chez OB. Un gène paralogue, RwNUDX1-2, a été découvert chez Rw et il a été démontré que son expression présentait une corrélation avec la production sesquiterpènes, en particulier de E,E-farnesol. Une série d'analyses in vitro et in vivo ainsi qu'une analyse de corrélation ont permis de vérifier la fonction de RhNUDX1-1, qui hydrolyse le géranyl diphosphate (GPP) en géranyl monophosphate (GP). Une phosphatase non identifiée pourrait catalyser la transformation du GP en géraniol. Des expériences de fusion avec la Green Fluorescent Protein (GFP), suivies de transformation transitoire de feuilles de tabac, ont révélé que RhNUDX1-1 était localisée dans le cytoplasme. Les mêmes approches (analyses QTL, essais enzymatiques et expression transitoire) ont également été appliquées à RwNUDX1-2, démontrant sa fonction dans la production de E,E-farnesol. La cartographie de RwNUDX1-2 et la localisation subcellulaire de la protéine sont encore à l'étude. De plus, la cristallographie des protéines et la modélisation ont été employées pour étudier le mécanisme de l'interaction NUDX1-substrat et les acides aminés potentiellement importants pour la reconnaissance du substrat. Collectivement, ces données révèlent une voie alternative pour la biosynthèse des terpènes, en particulier le géraniol et E,E-farnesol, via l'hydrolyse des prényl diphosphates par les enzymes NUDX1. Nos résultats montrent que la production de composés volatils dans les pétales est fortement corrélée avec l’expression des gènes des voies de biosynthèse. Par conséquent, la régulation transcriptionnelle de RcNUDX1-1a et RwNUDX1-2 joue probablement un rôle important dans la production de parfum. Les promoteurs de RcNUDX1-1a, RcNUDX1-1b, et RwNUDX1-2 et deux facteurs de transcription (FT), RcbHLH79 (OB TF) et RwbHLH79 (Rw TF) ont ainsi été isolés et testés (Chapitre 4). Les FT candidats ont été choisis lors d’une analyse RNA-Seq (Chapitre 5). En utilisant des tests d'expression transitoire avec le gène rapporteur GUS (β-glucuronidase) dans les pétales de rose, il a été montré que les trois promoteurs pouvaient entraîner l'expression de GUS. Les deux FT ont ensuite été introduits dans des feuilles de tabac avec les promoteurs testés, pour voir s'ils étaient capables d'activer ces promoteurs. Aucune transactivation significative n'a été détectée, même si Rw TF semblait pouvoir activer une construction témoin (promoteur du gène de la tomate TPS5. Les transcriptomes de quatre cultivars de rose, dont deux produisent du géraniol mais pas de E,E-farnesol et deux autres produisent du E,E-farnesol mais pas de géraniol, ont été analysés (Chapitre 5) et ont abouti à une liste de FT putatifs pour une étude plus approfondie / Roses are one of the most popular ornamental plants, whose volatiles are not only involved in environmental interactions but also widely used for industries. Chapter 1 describes the cultivation history of roses, usages of rose fragrance, knowledge on the biosynthesis of rose scent compounds, as well as non-canonical biosynthesis pathways of other plant volatiles. Experimental chapters (Chapter 2 and 3) analyse the functions of two genes expressed in rose petals, both encoding Nudix hydrolase 1 (NUDX1) protein. NUDX1-1 gene (named RhNUDX1) was first discovered by comparing the transcriptomes of two rose cultivars, the scented Rosa x hybrida cv. ‘Papa Meilland’ (PM) and the unscented R. x hybrida cv. ‘Rouge Meilland’ (RM). RhNUDX1-1 was only expressed in scented PM and its expression exhibited a positive correlation with the monoterpenoid production in petals, especially geraniol. When studying a rose progeny of R. chinensis cv. ‘Old Blush’ (OB) and R. x wichurana (Rw), an orthologous gene RcNUDX1-1a was found in OB, whose expression also had positive correlation with geraniol emission. A paralogous gene in Rw, RwNUDX1-2, was discovered and it was shown that its expression displayed a correlation with the sesquiterpenoid production, especially E,E-farnesol. A series of in vitro and in vivo assays as well as correlation analyses verified the function of RhNUDX1-1, which hydrolysed geranyl diphosphate (GPP) to geranyl monophosphate (GP). The transformation of GP into geraniol is supposed to be processed by an, as yet, unidentified phosphatase. The prediction of the localisation together with green fluorescent protein (GFP) fusion experiments revealed that RhNUDX1-1 was located in the cytosol. A series of approaches (QTL analyses, enzymatic assays and transient expression studies) were also applied to RwNUDX1-2, demonstrating its function in the production of E,E-farnesol. Mapping of RwNUDX1-2 and subcellular localization of the protein are still under investigation. Furthermore, protein crystallography and protein modelling illustrated the NUDX1-substrate interaction and proposed several residues that may be important for substrate recognition, although further experimental and computational data are required to gain more insight into the enzymatic mechanism. Collectively, these data revealed an alternative pathway for the biosynthesis of terpenoids, especially geraniol and E,E-farnesol, in rose, via the hydrolysis of prenyl diphosphates by NUDX1 enzymes. Transcriptional regulation of RcNUDX1-1a or RwNUDX1-2 probably plays an important role in the scent production by rose petals. Therefore, three promoters, pOB1a (promoter of RcNUDX1-1a), pOB1b (promoter of RcNUDX1-1b, not expressed in rose petals), pRw (promoter of RwNUDX1-2) were cloned and tested (Chapter 4). In addition, two transcription factors (TFs), RcbHLH79 (OB TF) and RwbHLH79 (Rw TF) candidates were chosen via RNA-Seq analysis as their expression correlated with expression of RcNUDX1-1a or RwNUDX1-2, respectively (Chapter 5). Using transient expression assays with a reporter gene, β-glucuronidase (GUS) in rose petals, it was shown that all three promoters could drive the expression of GUS, suggesting that all of them are active. However, quantification of promoter activities is still needed. OB TF and Rw TF were introduced into Nicotiana benthamiana leaves together with the promoters driving GUS , to determine if they were able to activate these promoters. However, no significant transactivation was detected in any promoter-TF combination. The expression of the TF in the progeny was also analysed but, due to the similarity of the sequences of family members, no conclusive data were obtained. Transcriptomes of the petals four roses, two of which produce geraniol but not E,E-farnesol and two that produce E,E-farnesol but not geraniol, were analysed (Chapter 5) and this resulted in a list of putative scent related genes and transcription factors for further study

A plethora of magmatic processing occurs in magma reservoirs, where melts are stored prior to eruption. Magma reservoirs are complex, open systems, and often multiple reservoirs are partially inter-connected from source to surface, giving rise to the term 'volcanic plumbing system'. Parental melts feeding these reservoirs can have diverse and distinct geochemical and petrological characteristics, and be variably evolved or enriched. These melts can also bring with them a crystal cargo that may remain in equilibrium in the magma reservoir, but may also be modified by reaction, resorption, crystallisation and diffusion. Melts and crystals can be transported between reservoirs, from the upper mantle and through the crust, leading to melt mixing, reactions and volatile exsolution. Basaltic volcanic systems are fed by primitive melts, and due to the rapid ascent of melts and short magma storage times, these volcanoes provide the best means of unravelling the mantle and crustal contribution to geochemical heterogeneity observed in erupted samples. Despite the potential chemical complexity of a magma reservoir, evidence for magma processing and reaction can be preserved in melt inclusion suites and the compositional structure of their host crystals. Magmatic processes during storage and transport at two basaltic volcanoes are investigated using two carefully selected eruptions: the 1669 eruption at Mt. Etna, and the 2007 Father's Day eruption at Kīlauea. A suite of diverse geochemical, petrological and petrographical observations, made at a range of length-scales, are combined and interpreted in tandem with geophysical monitoring data. The conclusions of these studies shed light on the architecture of each volcano's plumbing systems and basaltic plumbing systems in general. This thesis is divided into two parts. The first study unravels the crustal and mantle processes controlling melt geochemical heterogeneity at Mt. Etna, Sicily, during the 1669 eruption, the largest eruption in historical times. The 1669 melt inclusion suite arises from the mixing of two basaltic melts with similar major element compositions but very different trace and volatile element compositions. The melt geochemistry suggests that at least one end-member melt has been heavily influenced by assimilation of carbonate in the crust. The elevation in alkalis, caused by carbonate assimilation, enhances carbon and sulfur solubility in one end member. The melt inclusion suite indicates that mixing of these melts occurred in the shallow crust shortly before eruption and this mixing may be the cause of the enhanced $CO_{2}$ fluxes prior to eruptions at Mt. Etna. The second study is split into two parts. Each uses the eruptive products of the Father's Day eruption at Kīlauea and aims to unravel the connectivity of the plumbing system between the summit and East Rift Zone, with a focus on timescales of storage and transport. The first part investigates the melt geochemistry in terms of heterogeneity and volatile composition, and the second investigates the crystal cargo in terms of features of the macro-scale crystal cargo distribution and the micro-scale geochemical zoning of individual crystals. The integration of observations and models from these two studies constrains the pressure, temperature and composition of source magma feeding the Father's Day eruption. The eruption is investigated in the context of the "magma surge'' event that preceded the intrusion, as well as within the context of the longer-term trends in Kīlauea geochemistry at the summit and East Rift Zone. Melt inclusion and matrix glass volatile systematics provide insights into the degassing path of the magma and the duration of magma transport to the surface is constrained by diffusion modelling. Estimated timescales for ascent by diffusion modelling of macrocryst major element composition, melt inclusion water content and the melt Fe$^{3+}$/Fe$_{tot}$ ratio are in agreement with timescales observed from the geophysical data of $< $8 hours from reservoir depth to eruption. Both studies emphasise how petrological observations can supplement geophysical monitoring datasets collected at the surface to aid our interpretation of volcanic behaviour and eruption forecasting.

Most plant oxylipins, a large class of diverse oxygenated polyunsaturated fatty acids and their derivatives, are produced through the lipoxygenase (LOX) pathway. Recent progress in dicots has highlighted the biological roles of oxylipins in plant defense responses to pathogens and pests. In contrast, the physiological function of LOXs and their metabolites in monocots is poorly understood. We cloned and characterized three maize LOXs ZmLOX10 ZmLOX11 and ZmLOX12. Both ZmLOX10 and ZmLOX11 apeared to be 13-LOX, whereas ZmLOX12 is a unique 9-LOX. Whereas leaf was the preferential site of ZmLOX10 expression, ZmLOX11 was strongly expressed in silks. Induction of these ZmLOX10 and ZmLOX12 by wounding and defense-related compounds suggested their role in plant resistance mechanisms against pests and pathogens. Abscisic acid, however, was the only inducer of ZmLOX11 in leaves. Higher increase in ZmLOX10 transcripts in maize infected by fungus Cochliobolus carbonum implicated this gene in resistance responses to necrotrophic pathogens. In addition, ZmLOX10 was shown to be the first reported LOX to be regulated by a circadian clock. It was found that ZmLOX10 was also inducible by low temperatures. Phenotypical studies of wild type and mutant near isogenic lines showed that expression of ZmLOX12, specific to underground organs, was required for pathogenesis of F. verticillioides on maize mesocotyls.