Protecting group and switchable pore-discriminating adsorption properties of a hydrophilic-hydrophobic metal-organic framework

Formed by linking metals or metal clusters through organic linkers, metal-organic frameworks are a class of solids with structural and chemical properties that mark them out as candidates for many emerging gas storage, separation, catalysis and biomedical applications. Important features of these materials include their high porosity and their flexibility in response to chemical or physical stimuli. Here, a copper-based metal-organic framework has been prepared in which the starting linker (benzene-1,3,5-tricarboxylic acid) undergoes selective monoesterification during synthesis to produce a solid with two different channel systems, lined by hydrophilic and hydrophobic surfaces, respectively. The material reacts differently to gases or vapours of dissimilar chemistry, some stimulating subtle framework flexibility or showing kinetic adsorption effects. Adsorption can be switched between the two channels by judicious choice of the conditions. The monoesterified linker is recoverable in quantitative yield, demonstrating possible uses of metal-organic frameworks in molecular synthetic chemistry as 'protecting groups' to accomplish selective transformations that are difficult using standard chemistry techniques.

Progressive deformation of glacial till due to viscoplastic straining and pore pressure variation

The stress regime in a cutting (slope) is complex, with different principle stresses acting in different directions along the potential failure plane. For example, stresses may be primarily in extension near the toe and in compression near the crest of a slope. Cuttings in heavily overconsolidated clays are known to be susceptible to progressive failure which usually starts at the toe of the slope. Softening and the development of rupture surfaces have been observed in the field and are well documented for London Clays. However, this failure mechanism is yet to be established for glacial tills. To better understand the progressive failure mechanism, this paper discusses a series of laboratory tests conducted on reconstituted glacial till samples from Northern Ireland. Initial observations indicate that, a soil with insitu stress states between 80-90% of peak strength may undergo significant viscoplastic straining as a result of the combination of pore-pressure cycling and elevated stress level.

Wave Damping Observed in Upwardly Propagating Sausage-Mode Oscillations Contained within a Magnetic Pore

We present observational evidence of compressible MHD wave modes propagating from the solar photosphere through to the base of the transition region in a solar magnetic pore. High cadence images were obtained simultaneously across four wavelength bands using the Dunn Solar Telescope. Employing Fourier and wavelet techniques, sausage-mode oscillations displaying significant power were detected in both intensity and area fluctuations. The intensity and area fluctuations exhibit a range of periods from 181 to 412 s, with an average period∼290 s, consistent with the global p-mode spectrum. Intensity and area oscillations present in adjacent band passes were found to be out of phase with one another, displaying phase angles of 6.°12, 5.°82,and 15.°97 between the 4170 Å continuum–G-band,G-band–Na i D1, and Na i D1–Ca ii K heights, respectively, reiterating the presence of upwardly propagating sausage-mode waves. A phase relationship of ∼0° between same-bandpass emission and area perturbations of the pore best categorizes the waves as belonging to the “slow” regime of a dispersion diagram. Theoretical calculations reveal that the waves are surface modes, with initial photospheric energies in excess of 35,000 Wm‑2. The wave energetics indicate a substantial decrease in energy with atmospheric height, confirming that magnetic pores are able to transport waves that exhibit appreciable energy damping, which may release considerable energy into the local chromospheric plasma.

An evaluation of strain softening of glacial tills as a result of pore pressure dynamics.

Deep-seated progressive failures of cuttings in heavily overconsolidated clays have been observed in the field and are well documented, especially for London Clays (Potts, Kovacevic, & Vaughan, 1997; Smethurst, Powrie, & Clarke, 2006; Take, 2003), however, the process of softening and the development of a rupture surface in other clays, including the clay fraction of glacial tills, is still to be established. Recent decades have witnessed extreme weather conditions in Northern Ireland with dry summers and wet winters. The dynamics of this pore pressure variation can trigger strength reduction and progressive plastic straining, both of which will lead to slope failure. The aim of this research is to evaluate the effect of pore pressure variations on the deformation and long-term stability of large cuttings in glacial tills in Northern Ireland. This paper outlines the overall research program and presents initial laboratory findings (Carse, 2013).

Strength reduction of till under dynamic pore pressure condition

Cuttings in heavily overconsolidated clays are known to be susceptible to progressive deformation caused by creep and fatigue that usually begins at the toe of the slope. The progressive deformation leads to strength reduction with time at constant stress (or called softening) and could be accelerated by fluctuation of groundwater level associated with more extreme rainfall events predicted through climate change. The purpose of this paper is to assess the mechanism of progressive deformation due to creep and fatigue using element testing on samples of till. The samples were subjected to fully drained loading and the deviator stresses were held constant at various percentages of peak failure stress, while the pore water pressure was kept static or dynamic (fluctuating ±5 kPa) over a period of time. The results have shown that the samples experienced significant deformation even at a higher factor of safety (i.e. the failure deviator stress/deviator stress at which the pore water pressure was fluctuated) under pore water pressure dynamics.

Adsorption behavior of α-cypermethrin on cork and activated carbon

Studies were undertaken to determine the adsorption behavior of α-cypermethrin [R)-α-cyano-3-phenoxybenzyl(1S)-cis- 3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylate, and (S)-α-cyano-3-phenoxybenzyl (1R)-cis-3-(2,2-dichlorovinyl)-2,2- dimethylcyclopropanecarboxylate] in solutions on granules of cork and activated carbon (GAC). The adsorption studies were carried out using a batch equilibrium technique. A gas chromatograph with an electron capture detector (GC-ECD) was used to analyze α-cypermethrin after solid phase extraction with C18 disks. Physical properties including real density, pore volume, surface area and pore diameter of cork were evaluated by mercury porosimetry. Characterization of cork particles showed variations thereby indicating the highly heterogeneous structure of the material. The average surface area of cork particles was lower than that of GAC. Kinetics adsorption studies allowed the determination of the equilibrium time—24 hours for both cork (1–2 mm and 3–4 mm) and GAC. For the studied α-cypermethrin concentration range, GAC revealed to be a better sorbent. However, adsorption parameters for equilibrium concentrations, obtained through the Langmuir and Freundlich models, showed that granulated cork 1–2 mm have the maximum amount of adsorbed α-cypermethrin (qm) (303 μg/g); followed by GAC (186 μg/g) and cork 3-4 mm (136 μg/g). The standard deviation (SD) values, demonstrate that Freundlich model better describes the α-cypermethrin adsorption phenomena on GAC, while α-cypermethrin adsorption on cork (1-2 mm and 3-4 mm) is better described by the Langmuir. In view of the adsorption results obtained in this study it appears that granulated cork may be a better and a cheaper alternative to GAC for removing α-cypermethrin from water.

The development of automated methods for the determination of trace concentrations of carbomate pesticides in water using solid sorbent pre-concentration methods and high performance liquid chromatography /

Several automated reversed-phase HPLC methods have been developed to determine trace concentrations of carbamate pesticides (which are of concern in Ontario environmental samples) in water by utilizing two solid sorbent extraction techniques. One of the methods is known as on-line pre-concentration'. This technique involves passing 100 milliliters of sample water through a 3 cm pre-column, packed with 5 micron ODS sorbent, at flow rates varying from 5-10 mUmin. By the use of a valve apparatus, the HPLC system is then switched to a gradient mobile phase program consisting of acetonitrile and water. The analytes, Propoxur, Carbofuran, Carbaryl, Propham, Captan, Chloropropham, Barban, and Butylate, which are pre-concentrated on the pre-column, are eluted and separated on a 25 cm C-8 analytical column and determined by UV absorption at 220 nm. The total analytical time is 60 minutes, and the pre-column can be used repeatedly for the analysis of as many as thirty samples. The method is highly sensitive as 100 percent of the analytes present in the sample can be injected into the HPLC. No breakthrough of any of the analytes was observed and the minimum detectable concentrations range from 10 to 480 ng/L. The developed method is totally automated for the analysis of one sample. When the above mobile phase is modified with a buffer solution, Aminocarb, Benomyl, and its degradation product, MBC, can also be detected along with the above pesticides with baseline resolution for all of the analytes. The method can also be easily modified to determine Benomyl and MBC both as solute and as particulate matter. By using a commercially available solid phase extraction cartridge, in lieu of a pre-column, for the extraction and concentration of analytes, a completely automated method has been developed with the aid of the Waters Millilab Workstation. Sample water is loaded at 10 mL/min through a cartridge and the concentrated analytes are eluted from the sorbent with acetonitrile. The resulting eluate is blown-down under nitrogen, made up to volume with water, and injected into the HPLC. The total analytical time is 90 minutes. Fifty percent of the analytes present in the sample can be injected into the HPLC, and recoveries for the above eight pesticides ranged from 84 to 93 percent. The minimum detectable concentrations range from 20 to 960 ng/L. The developed method is totally automated for the analysis of up to thirty consecutive samples. The method has proven to be applicable to both purer water samples as well as untreated lake water samples.

Vulnérabilité cardiaque au stress au cours du remodelage ventriculaire pathologique : rôle de la mitochondrie et du pore de perméabilité transitionnelle (PTP)

L’objectif central de cette thèse de Doctorat était d’investiguer les dysfonctions mitochondriales qui surviennent précocement au cours de la phase compensée du remodelage ventriculaire pathologique et qui pourraient jouer un rôle causal dans la progression vers l’insuffisance cardiaque. Nos travaux antérieurs, réalisés à l’aide d’un modèle de surcharge volumique chronique induite par une fistule aorto-cavale (ACF) chez le Rat WKHA, ont montré qu’au cours du remodelage ventriculaire, les mitochondries développaient une vulnérabilité à l’ouverture du pore de perméabilité transitionnelle (PTP : un élément clé de la signalisation de la mort cellulaire) [1]. Ceci était observable au stade compensé du remodelage en absence des dysfonctions mitochondriales majeures typiquement observées dans le cœur insuffisant. Ces résultats nous ont amenés à suggérer que la vulnérabilité à l’ouverture du PTP pourrait constituer un mécanisme précoce favorisant la progression de la cardiopathie. Dans l’étude 1 de cette thèse, nous avons tenté de tester cette hypothèse en induisant une ACF chez deux souches de rats affichant de très nettes différences au niveau de la propension à développer l’insuffisance cardiaque : les souches WKHA et Sprague Dawley (SD). Nos études in vitro sur organelles isolées et in situ sur l’organe entier ont permis de confirmer que, dans le cœur ACF, les mitochondries développent une vulnérabilité à l’ouverture du PTP et à l’activation de la voie mitochondriale de la mort cellulaire lorsqu’exposées à des stress pertinents à la pathologie (surcharge calcique, ischémie-reperfusion [I-R]). Cependant, bien que comparativement aux animaux WKHA, les animaux SD démontraient un remodelage ventriculaire plus rapide et prononcé et une progression précoce vers l’insuffisance cardiaque, aucune différence n’était observable entre les deux groupes au niveau des dysfonctions mitochondriales, suggérant quelles ne sont pas à l’origine de la progression plus rapide de la pathologie chez la souche SD, à tout le moins en réponse à la surcharge volumique. Nous avons par la suite déterminé, à l’aide des mêmes approches expérimentales, si cette vulnérabilité mitochondriale était observable dans une cardiopathie d’étiologie différente, plus spécifiquement celle qui est associée à la dystrophie musculaire de Duchenne (DMD), une maladie génétique causée par une mutation de la protéine dystrophine. Nos études menées (études 2-4) sur de jeunes souris mdx (le modèle murin de la DMD) exemptes de tout signe clinique de cardiopathie n’ont révélé aucune différence au niveau des fonctions mitochondriales de base. Cependant, tout comme dans le modèle d’ACF, les mitochondries dans le cœur de souris mdx étaient significativement plus vulnérables à l’ouverture du PTP lorsque soumises à une I-R (étude 2). Par ailleurs, nous avons démontré que l’administration aiguë de sildénafil aux souris mdx induisait une abolition de l’ouverture du PTP et de ses conséquences signalétiques, une diminution marquée du dommage tissulaire et une meilleure récupération fonctionnelle à la suite de l’I-R (étude 3). Nous avons ensuite testé chez la souris mdx l’administration aiguë de SS31, un peptide anti-oxydant ciblé aux mitochondries, cependant aucun effet protecteur n’a été observé, suggérant que le tamponnement des radicaux libres est d’une utilité limitée si les perturbations de l’homéostasie calcique typiques à cette pathologie ne sont pas traitées simultanément (étude 4). Globalement, les travaux effectués au cours de cette thèse démontrent que la vulnérabilité à l’ouverture du PTP constitue une dysfonction précoce et commune qui survient au cours de remodelages ventriculaires pathologiques d’étiologies différentes. Par ailleurs, ces travaux suggèrent des stratégies d’intervention pharmacologiques ciblant ce processus, dont l’efficacité pour la prévention de l’insuffisance cardiaque demande à être établie.

Les discours sur le roman français de 1734 à 1755 : analyse générique et rhétorique (Lenglet-Dufresnoy, Bougeant, Porée, Jacquin)

Cette étude examine comment différents textes du XVIIIe siècle traitent du roman. L’hypothèse est la suivante : le genre choisi pour parler du roman participe de manière intrinsèque à la critique ou à l’apologie véhiculée dans l’œuvre. Le corpus est composé de quatre textes plus ou moins (re)connus par les historiens de la littérature narrative : De l’Usage des romans (1734) de Lenglet-Dufresnoy, le Voyage merveilleux du Prince Fan-Férédin dans la Romancie (1735) du père Bougeant, De Libris qui vulgò dicuntur Romanenses (1736) du père Porée et les Entretiens sur les romans (1755) du père Jacquin. À l’aide d’une méthode hybride d’analyse générique et d’analyse rhétorique du discours, cette étude s’intéresse aux genres employés par les auteurs du corpus (le traité, le roman, le discours académique et l’entretien) de même qu’à trois thématiques argumentatives reliées au roman (le poison, l’amour et la femme).

Effet de l'hypertrophie cardiaque physiologique et pathologique sur la régulation du pore de perméabilité transitionnelle

Thèse numérisée par la Division de la gestion de documents et des archives de l'Université de Montréal

Vulnérabilité cardiaque au stress au cours du remodelage ventriculaire pathologique induit par surcharge volumique : rôle du pore de perméabilité transitionnelle (PTP)

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.

Implication de la cyclophiline-D et du pore de perméabilité transitionnelle dans la vulnérabilité mitochondriale du coeur hypertrophié

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal