Classification of fine particles using a Taylor-Couette device

The study of fine particle classification is common, especially since a well defined particle size distribution is important in most processes and products. Many methods have been developed to classify micron-size particles, and although each has its own advantage, most cannot classify particles to an extremely narrow range. This is partly due to the cohesive nature of fine particles, which can be due to electrostatic attraction, moisture, or van der Waals forces. In order to overcome this problem, a wet method of classification has been chosen here. Taylor vortices, discovered in 1923, develop in the fluid contained in the annulus of two concentric rotating cylinders. It has been shown in recent years that Taylor vortices can be used to classify particles regardless of their size (which may range from a few microns to millimeters) and density difference between the particles and fluid. This method also allows for a semicontinuous throughput of particles. The present work outlines the use of Taylor vortices to classify fine particles to a narrower size distribution. The main objective here is to determine the parameters affecting classification of glass spheres of various initial distributions. Factors such as rotational velocity, system annulus size, particle to fluid density ratio, and particle feed rate have been investigated. The results obtained showed that both rotational velocity and particle feed rate have a significant effect on classification while classification for particles of size 10 µm or less was not feasible for the experimental parameter range studied here. The conclusions were supported both numerically and experimentally --Abstract, page iii

Structural optimisation of diffusion-driven degradation processes

In the field of structural engineering, structures are developed and calculated. The stresses and deformations resulting from mechanical loads are determined, and the structures are dimensioned to ensure load-bearing capacity, usability and durability in accordance with standards. The application of structural optimisation algorithms enables the development of more efficient and economical building structures, whereby maximum permissible stresses can be exhausted. However, standardised calculations take environmental influences, such as chemical impact, only via so-called exposure classes and resulting material properties into account. Detailed calculations on the influence of stresses and deformations of the structures, especially due to the long-term chemical influence and resulting material degradation, are often neglected. For example, specific stress constraints may be exceeded. Within the scope of the present work, a numerical programme is developed, enabling an efficient optimisation of mechanical structures that are additionally burdened by degradation processes due to diffusive concentrations. For this purpose, a mechanicalchemical- degradation coupled model is developed. Within the framework of classical structural mechanics, the developed material behaviour is presented, taking into account modified physical principles of continuum mechanics to describe a mechanical-chemicaldegradation coupled processes. With the help of the fundamentals of the Finite Element Method (FEM), the solution of the non-linear problem is outlined in detail. Furthermore, the developed structural analysis is embedded in a mathematical algorithm of gradient-based structural optimisation. The optimisation allows a deeper analysis and reduction of the harmful effects due to the influence of acting chemical concentrations. A variational approach to structural optimisation provides the simultaneous integration of analytically prepared sensitivity analysis with the structural analysis for embedding the continuum mechanical formulations. Thus, efficient structural optimisation of the introduced mechanical-chemical-degradation model is comprehensively presented. The mathematical model with the required derivations as well as discretisation is documented and implemented in a computer-based model

Abiotic stress hormesis in carrots : disease resistance, physiological stress responses and enhancement of volatile phytochemicals

L'entreposage à long terme des carottes (Daucus carota L.) est principalement limité par les maladies fongiques et les pourritures post-récolte. L'utilisation du potentiel physiologique des carottes pourrait être une alternative intéressante aux applications de fongicide pour lutter contre ces maladies. Les stress abiotiques sont de nature oxydative et s'avèrent souvent nocifs aux plantes et aux tissus végétaux à fortes doses, mais peuvent induire des mécanismes protecteurs / adaptatifs à faibles doses, un phénomène biologique appelé hormèse. Cependant, exception faite des rayons UV-C, on sait peu de choses quant aux possibles effets hormétiques des stress abiotiques sur les produits post-récolte tel que les carottes. Ainsi l'objectif général de ce travail était d'établir l'existence de l'hormèse chez les racines de carotte suite à l'exposition à divers stress abiotiques, incluant les radiations UV, la lumière blanche, la chaleur, les ultrasons, l'ozone et l'éthylène et d'étudier l'effet des doses hormétiques de ces stress sur la résistance aux maladies. Plus précisément, la démarche consistait à déterminer les doses hormétiques des stress dans l'intensification de la résistance aux maladies chez les carottes conservées à 4 °C, suivre les changements physiologiques et biochimiques des carottes exposées aux stress, et évaluer l'induction ou l'accroissement des teneurs de différents phyto-composés aux propriétés antimicrobiennes et/ou bénéfiques pour la santé (connues ou potentielles) chez les carottes exposées, et leur évolution au cours d'un entreposage de 42 jours à 4 °C. Tous les stress abiotiques sélectionnés présentaient le phénomène d'hormèse chez les carottes entreposées à 4 °C (> 95% humidité relative) avec une résistance accrue, à divers degrés, à la maladie causée par Botrytis cinerea. Les doses hormétiques des stress étaient: 7,0 kJ∙m⁻² (UV-B); 30 kJ∙m⁻² (lumière blanche); 60 min (chaleur, 36 °C); 30 min (ultrasons, 135 W); 6,0 h (ozone, 5,0 ppm) et 6,5 h (éthylène, 250 ppm). Appliqués aux doses hormétiques, les ultrasons avec H₂O₂, les UV-B, l'ozone, la lumière blanche et l'éthylène étaient les stress les plus efficaces (60 à 65% réduction de la maladie). La deuxième partie de cette étude consistait à suivre au cours de l'entreposage les changements physiologiques (taux de respiration, fuite d'électrolytes et perte de poids) et biochimiques (capacité antioxydante) des carottes, suite à l'exposition aux stress susmentionnés. Les ultrasons avec H₂O₂ et l'ozone, ont davantage, bien que transitoirement, provoqué des changements dans les caractéristiques physiologiques et biochimiques des carottes exposées. De plus, les D₅₀ (doses efficaces à 50%), déterminées à partir des courbes de réponse physiologique, sont comparables aux doses hormétiques obtenue en utilisant la réponse de résistance à la maladie. Dans la troisième partie du travail, l'effet des stress (appliqués aux doses hormétiques) sur les carottes entreposées a été évalué sur l'induction / l'augmentation des niveaux de quatre phyto-composés, antimicrobiens connus ou potentiels, et sur leur contribution à la résistance induite aux maladies. La lumière blanche a été la plus efficace dans l'induction de la phytoalexine 6-méthoxymelléine, suivie des UV-C, des ultrasons avec H₂O₂, de l'ozone et des UV-B; la lumière blanche et les UV-C dans l'augmentation des polyacétylènes antifongiques constitutifs, le falcarinol et le falcarindiol. La lumière blanche et l'éthylène ont augmenté les niveaux de myristicine. Dans l'ensemble, la lumière blanche et les UV, suivis des ultrasons avec H₂O₂ et de l'éthylène, ont été les plus efficaces pour augmenter les niveaux de ces composés. La 6-méthoxymélléine s'est révélée comme le principal phyto-composé impliqué dans la résistance induite par les stress abiotiques, tandis que les polyacétylènes, le falcarinol et le falcarindiol dans une moindre mesure, joueraient un rôle d'adjuvant. La myristicine ne semble jouer aucun rôle dans la résistance induite aux maladies chez les carottes. Enfin, l'examen des profils des phyto-composés relativement volatils bénéfiques pour la santé (phénylpropanoïdes, terpénoïdes, polycétides et polyacétylènes) obtenus par GC-MS montre une augmentation à des degrés divers de tous les composés en réponse aux différents stress hormétiques. Dans l'ensemble, la lumière blanche, les ultrasons avec H₂O₂, l'ozone et les UV-C se sont montrés efficaces pour augmenter les niveaux des diverses classes de composés précités. Considérant l'amélioration de la résistance aux maladies; l'augmentation des niveaux des phyto-composés, en particulier de la phytoalexine 6-méthoxymélléine; protecteurs des plantes et/ou bénéfiques pour la santé, la lumière blanche, les ultrasons avec H₂O₂, ou l'ozone pourraient être des stress hormétiques souhaitables pour le traitement des carottes entreposées.Long-term storage of carrots (Daucus carota L.) is limited mainly by fungal diseases and decay. Utilizing the physiological potential of the produce to elevate disease resistance could be an attractive alternative to fungicide applications to control diseases in stored carrots. Abiotic stresses are oxidative in nature and often prove harmful to plants at high doses, but may induce protective/adaptive mechanisms at low doses, a biological phenomenon known as hormesis. However, little is known regarding the existence of hormesis of other abiotic stresses, other than UV-C radiation, in postharvest crops, including carrots, nor their hormetic effects in carrots, if any. The overall objective of this work was to establish the existence of hormesis phenomenon of various abiotic stresses, including UV radiations and white light (WL), heat, ultrasound (US), ozone (O₃), and ethylene (ET) in carrot roots, and investigate the potential of pre-storage treatment with hormetic doses of those stresses to enhance the disease resistance of stored carrots. Specifically, the approach consisted of determining the hormetic doses of stresses in the intensification of disease resistance in carrots stored at 4 °C; monitoring the physiological and biochemical changes in the stress-exposed carrots; and evaluating the induction or enhancement of phyto-compounds with antimicrobial and/or health-beneficial properties of the exposed carrots, and their dynamics during storage of 42 days. All the selected abiotic stresses exhibited the phenomenon of hormesis in carrots stored at 4 °C (> 95% relative humidity) with enhanced disease resistance against decay caused by Botrytis cinerea to varying degrees. The hormetic doses of the selected abiotic stresses for the induction of disease resistance in carrots were: 7.0 kJ∙m⁻² (UV-B), 30 kJ∙m⁻² (WL); 60 min (heat at 36 °C), and 30 min (US at 135 W); 6.0 h (O₃ at 5 ppm); and 6.5 h (ET at 250 ppm). Hormetic doses of US+H₂O₂, UV-B, O₃, WL, and ET were the most effective among the stresses to induce resistance (60-65% disease reduction). The second part of this research work was to evaluate changes in the physiological(respiration rate, electrolyte leakage, and weight loss) and biochemical (antioxidant capacity) characteristics of the carrots, following exposure to the afore-mentioned stresses during 6 weeks of storage. Among the stresses, US+H₂O₂ and O₃, most markedly, albeit transiently, caused changes in the physiological and biochemical characteristics of the exposed carrots. Furthermore, the D₅₀ (effective dose at 50%) doses, determined from the sigmoidal stress dose-changes in the physiological and biochemical response curves appeared to represent the hormetic doses comparable to those obtained using the disease resistance response. The third part of the work evaluated the hormetic doses of abiotic stresses for their capacity to induce/enhance the levels of four targeted phyto-compounds, either known or potential antimicrobials, and their contribution to the disease resistance against B. cinerea. Hormetic WL was most effective in the induction of the isocoumarin phytoalexin, 6-methoxymellein (6-MM), followed by UV-C, US+H₂O₂, O₃, and UV-B stresses; WL and UV-C in the enhancement of the constitutive antifungal polyacetylenes, falcarinol (FaOH) and falcarindiol (FaDOH); and WL and ET were effective in enhancing the insecticidal phenylpropene, myristicin (MYR). Overall, WL, UV radiations, followed by US+H₂O₂ and ET, were most effective in the enhancement of those four compounds. The phytoalexin, 6-MM, was the principal phyto-compound involved in the resistance, while FaOH and FaDOH played an adjuvant role, and MYR did not seem to play any role. The final portion of this work examined the profiles of relatively volatile health-beneficial phyto-compounds in carrots using GC-MS and their enhancement in response to hormetic abiotic stresses. All the phyto-compounds (phenylpropanoids, terpenoids, polyketides, and polyacetylenes) were enhanced to varying degrees by different hormetic stresses. Overall, the effective stresses for the enhancement of diverse classes of volatile health-beneficial phyto-compounds were WL, US+H₂O₂, O₃, and UV-C. From the standpoints of improved disease resistance; the enhancement of antimicrobial targeted phyto-compounds, specifically the phytoalexin, 6-MM; and that of volatile compounds that are both plant-protecting and health-beneficial, application of hormetic stresses, WL, US+H₂O₂, or O₃, could be desirable in practice, for not only controlling diseases in carrots, but also improving their health-beneficial properties

Analysis of the Icelandic Oral Hymn Tradition as Seen in the Twentieth-century Enthnographic Recordings of Stridsmenn Krist ( Christ Bears His Cross )

The Hymns of the passion are a collection of Icelandic poems (1656-1659) that have been important to Icelandic religious life since the seventeenth century. Until an organ was first brought to Iceland in 1840, hymns were unaccompanied both in church and in the home. Though the words of the hymns were reprinted several times, the musical notation seldom accompanied them, allowing for a strong oral tradition to form. I transcribed 31 field recordings of the hymn Stridsmenn Krist ( Christ bears his cross ). I then compared these transcriptions in order to identify rhythmic and melodic variations. The final stage of my research is grouping similar variants to determine possible trends in oral tradition with respect to age or geographic region

Pneumoconiosis

Pneumoconiosis is any lung disease caused by the inhalation of organic or nonorganic airborne dust and fibers. Patients usually encounter these inhalants in the workplace environment, and therefore it is known as an occupational disease. The most frequently encountered types of pneumoconiosis are asbestosis, silicosis, and coal miner\u27s lung. These particles cause inflammation and fibrosis in the lung resulting in irreversible lung disease. Prevention relies on workplace exposure management and health management regulations

Structural optimisation of diffusion driven degradation processes

In this article, we propose an optimisation framework that can contribute to the prevention of premature failure or damage to building structures and can thereby strengthen their longevity. We concentrate on structures that are contaminated by chemical substances and that have strong destructive effects on the material. The aim of this contribution is a mathematical algorithm that allows the optimisation of a structure exposed to chemical influences and thus the assurance of the static load capacity. To achieve this, we present a coupled mechanical-diffusion-degradation approach embedded in a finite element (FE) framework. Furthermore, we integrate an optimisation algorithm to reduce material degradation. In this paper, we establish shape optimisation of a structure with a gradient based optimisation algorithm

Zircon U-Pb Geochronology of the Inish Granite Pluton: Evidence for the long-lived emplacement of the south Connemara Granites

Two new U-Pb geochronology dates from the Inish Granite (main granite: 423.21 ± 0.30 Ma; marginal granite 428 +17/-11 Ma) show that emplacement of the south Connemara Granites extended from approximately 430 Ma to 380 Ma. These ages are consistent with the recent model Re-Os age determinations for the Omey Granite (422.5 ± 1.7 Ma) and suggest that the Letterfrack and Roundstone granites were also emplaced around the same time. Field relations of the Inish Granite show relative age differences for the main and marginal granite, with quartz-feldspar porphyry dikes cross-cutting the marginal granite but not the main granite. These relations suggest that emplacement of the marginal granite occurred, followed by the quartz-feldspar porphyry dikes, and assembly of the Inish Granite culminated with intrusion of the main phase. The time span of emplacement of the calc-alkaline south Connemara Granites is similar to that of the mid-Paleozoic alkalic plutons located in southeastern New England, USA (426 Ma to 377 Ma), linking hypothesised intraplate rifting in West Avalonia and prolonged magmatism in Laurentia. This provides further support for the model of Avalonia subduction beneath Laurentia in the Siluro-Devonian time period, and suggests that the end of magmatic activity for both suites indicated the complete closure of the Iapetus Ocean.Bachelor of Scienc

Effect of Temperature on the Surface Plasmon Resonance (SPR) Mode along a Metal - Liquid Crystal Interface

204-208The effect of temperature on the surface plasmon mode parameters for surface plasmons (SPs) excited by prism coupling along the interface of a thin silver film and homeotropically aligned liquid crystals (LCs), 5CB and UCF25 are theoretically studied. The change in the SPR angle of dip with temperature is found to be almost linear below the clearing temperature of the LCs. The temperature sensitivity is found to be high in the temperature range where the LC behaves as an anisotropic material. The sensitivity is found to be higher when SPR reflectance at a fixed incident angle is used as the variable parameter. The shift in SPR angle of dip is found to be linear with the change in birefringence of the LC due to the change in temperature. The change in SPR parameters with temperature is found to be much lesser in the temperature range where the LC behaves as an isotropic material