A Soft Chemistry Approach to Extended [Co6Se8] Materials

This dissertation describes advances toward creating programmable building blocks and assembling them into new, tailored materials. I describe extended materials formed of bonded sets of cobalt selenide clusters. Rationally designed chemical transformations that form these sets give us precise control over the extent and dimensionality of the material. The cobalt selenide clusters fundamental to this study are members of a larger class of clusters with the M6E8 core (M = metal, E = chalcogen). Chapter 1 introduces this family of clusters and reviews examples of previously made materials. Chapter 2 unveils a family of site-differentiated clusters, Co6Se8(CO)x(PEt3)6-x, their substitution reactions, and assembly into bridged dimers and trimers. Electrochemical methods were used to investigate electronic coupling between the cores, by comparing the electrochemical behavior of the dimer and trimer relative to their monomeric counterparts. We further performed magnetic susceptibility measurements of the monomers and assemblies. Chapter 3 introduces electrocrystallization as a method to synthesize extended, crystalline, solid state compounds from superatomic building blocks. By electrocrystallizing redox-active [Co6Se8] clusters with labile ligands in the presence of an ionic template, we created a crystalline polymeric material that exhibits weaving at the nanoscale. Chapter 4 presents a metal coordination approach to [Co6Se8] materials via reactive groups on the capping ligands. The redox-activity and multinuclearity of the superatom components creates a new level of complexity and synthetic sophistication to previously reported frameworks. In collaboration with Prof. Christopher Bejger (University of North Carolina at Charlotte), I installed carboxylate groups on the surface of the cluster. With this building block in hand and a simple metal salt, Zn(NO3)2, we discovered two sets of distinct solvothermal reaction conditions that yielded two different solids. Both are homogenous, crystalline, porous solids whose dimensionality is tuned by subtle changes in reaction conditions. I further showed that the dimensionality could be further reduced by chemical exfoliation to yield free-floating sheets of zinc-coordinated clusters in which the porosity and redox-activity of the bulk solid is preserved. Finally, Chapter 5 outlines a novel chemical transformation that dimerizes [Co6Se8] units to form a material with an expanded core, [Co12Se16], that exhibits electronic and optical properties distinct from the parent monomer. To accomplish this dimerization, I installed a reactive carbene on the [Co6Se8] core to create a latent fusion site. We show by cyclic voltammetry, infrared spectroscopy, single crystal X-ray diffraction, and density functional theory calculations that the resulting fused [Co12Se16] material exhibits strong electronic coupling and electron delocalization. These chapters present novel synthetic approaches toward creating [Co6Se8] materials with tuned dimensionality, size, and extensive charge delocalization

La modélisation au coeur de l'apprentissage des sciences expérimentales : la digestion

La digestion au cycle 3 : un sujet d'apprentissage abordant de nombreux concepts complexes, difficiles à enseigner par l'impossibilité de visualiser et de manipuler le réel. Afin de proposer une alternative à ces obstacles, ce mémoire présente une séquence pour des élèves de CM1 basée sur cinq modélisations : une pour permettre une représentation juste du tube digestif et quatre autres pour visualiser et comprendre les actions mécaniques et le rôle de la digestion. De nombreuses questions se sont naturellement imposées lors de notre pratique. Ainsi, à partir de l'étude des modèles pédagogiques existants et l'utilisation de la modélisation comme outil et support à l'apprentissage, nous avons tenté de dégager les apports et les limites de celle-ci dans l'évolution des conceptions initiales des élèves et dans l'acquisition de nouvelles notions

The Great Depression? Challenging the Periodization of French Business History in the Interwar Period

In this essay we aim to demonstrate that economic and business historians‘ tendency to use moments of severe economic turbulence as turning points does not always fit with a periodization based on corporate change. In fact, our essay shows that the economic downturn of the early 1930s did not impact all companies‘ long-term strategies the same way and that it sometimes fostered management innovations or helped to reinforce nascent ideas. To illustrate our point we have chosen to look at two companies that, despite the Great Depression, developed new administrative methods and marketing innovations. They acted not only in a defensive mode but also to prepare for better times. The cases were deliberately taken from very different sectors. The first deals with heavy industry, using the metallurgy and chemicals company AFC-Pechiney; the second considers the family-owned and -managed retail group Galeries Lafayett

The Great Depression? Challenging the Periodization of French Business History in the Interwar Period

In this essay we aim to demonstrate that economic and business historians‘ tendency to use moments of severe economic turbulence as turning points does not always fit with a periodization based on corporate change. In fact, our essay shows that the economic downturn of the early 1930s did not impact all companies‘ long-term strategies the same way and that it sometimes fostered management innovations or helped to reinforce nascent ideas. To illustrate our point we have chosen to look at two companies that, despite the Great Depression, developed new administrative methods and marketing innovations. They acted not only in a defensive mode but also to prepare for better times. The cases were deliberately taken from very different sectors. The first deals with heavy industry, using the metallurgy and chemicals company AFC-Pechiney; the second considers the family-owned and -managed retail group Galeries Lafayett

Efficacité des méthodes d'adsorption-élution utilisant la poudre ou la laine de verre pour la concentration des virus dans les effluents de stations d'épuration

Pour rechercher les virus dans les eaux usées traitées, une nouvelle méthode d'adsorption-élution sur laine de verre a été appliquée comparativement à la méthode d'adsorption-élution sur poudre de verre. Lorsque la technique de concentration sur laine de verre est utilisée, c'est dans les 25 premiers ml de l'éluat que la majorité des virus poliomyélitique est retrouvé (89 à 94 %). La comparaison des méthodes de concentration des virus indigènes à partir d'échantillons d'effluents provenant de deux stations d'épuration biologique de la Côte d'Azur (Cagnes-sur-Mer et Nice), a mis en évidence la supériorité de cette nouvelle méthode : les taux de positivité ont été respectivement de 85 % vs 38 % pour l'effluent de Cagnes-sur-Mer et 100 % vs 44 % pour l'effluent de Nice. De même, les titres en virus indigènes après concentration ont varié de 0 à 250 NPPUC/l pour la méthode sur laine de verre contre 0 à 25,5 NPPUC/l pour la méthode sur poudre de verre. La différence constatée entre les méthodes est statistiquement significative après analyse de variance (p = 0,0119 pour l'effluent de Cagnes-sur-mer et p < 0,0001 pour l'effluent de Nice). De plus, la technique sur laine de verre ne nécessite ni l'abaissement du pH, ni le changement de la composition ionique de l'échantillon d'eau à analyser.Biological treatment of sewage in waste water plants does not allow elimination of the whole of the microbial load. Discharge of the treated sewage results in viral pollution of river, lakes and seas, a potential hazard for the health that has to be monitored. The amont of virus in waste water beeing low, concentration from the samples brought to the laboratory is rendered necessary. The aim of this study was to evaluate the efficacy of a new adsorption-elution method on glass wool to recover indigenous viruses from effluents of the cities of Cagnes and Nice (Alpes-Maritimes, France). In order to evaluate its efficiency we compared it to the regular adsorption-elution method on glass powder. As a preliminary we determined upon artificially contaminated 5 liter waste waters samples what detection of virus could be performed only in the first 25 ml of the 100 ml eluate, as in the glass powder concentration method. Results show chat virus titers found in that first fraction of eluate were close to those in the total sample. Thus from 3 samples containing 1.60 108 MPNCU/5 l, 1.96 107 MPNCU/5 l and 4.32 104 MPNCU/5 l we found in that first fraction respectively 1.50 104 MPNCU/5 l (94 %), 1.80 107 MPNCU/5 l (92 %) and 3.85 104 MPNCU/5 l (89 %); these recovery rates are not significantly different by comparison of confidence limits. The glass powder method, necessitates preliminary treatment of the sample : acidification to pH 3.5 and adjunction of AICI3 at a final concentration of 5.10-4 M. After flowing the acidified sample through 100 g of borosilicated glass powder at a rate of 10 l/10 min inside a decantation ampulla. Then adsorbed virus may be eluted from the sedimentated glass powder with 100 ml of borate buffer containing 3 % beet extract, pH9 : the first 25 ml were collected into a flask containing 2.5 ml of a mixture of antibacterial and antifungal antibiotics. For the glass wool adsorption method, a 19 cm3 cartridge was packed with 5 g sodocalcic glass wool at a 0.4 g/cm3 density and rinced sequentially with : 10 ml 1N HCl, 10 ml deionised water, 10 ml 1N NaOH and lastly 40 ml deionised water. It was balanced with 200 ml deionised water. The sample, was pumped at a flow rate ca 10 l/h. Enumeration of viruses was performed by inoculating 40 microplate wells containing KB cells, and performing 3 passages 5 days each, after which the number of wells presenting with CPE was determined. This characteristic number allowed calculation of the most probable number of cytopathic units (MPNCU) with the 95 % confidence limit. The Box and Cox analysis of transformation was applied to the data. Since the calculated value of λ approximated zero (λ = - 0.29 for the Cagnes effluent and λ = - 0,062 for the Nice effluent), transformation of the gross data into logarithm was justified. To allow this transformation, the zero had to be substituted for by a value equal to half the limit sensitivity of the method (I well out of 40), i.e. 0.5. Distribution of the data being roughly log-normal, it was then possible to compare the results of the two methods by two-way analysis of variance, cross classification, without replica. The test for factor method was calculated according to the interaction since this factor is fixed. Overall it appeared that all 31 10-liter samples analysed contained viruses when results from bath methods were combined. Still no single method allowed virus recovery in a 100 % of cases, however the glass wool adsorption method found viruses in 29/31 vs 13/31 with the glass powder method. The new method detected virus in 11/13 (85 %) samples from Cagnes waste waters as well as in 18/18 (100 %) from Nice. Quantitative analysis of the viral titers indicates that, titers were higher following the glass wool adsorption method than following the glass powder adsorption method in 11/13 samples from Cagnes treatment plant and in 17/18 from Nice. Thus virus concentrations varied between 0 and 250 MPNCU/l (MGT= 4.6 MPNCU/l) for the Cagnes effluent and between 2 and 60 MPNCU/l (MGT= 7.5 MPNCU/I) for the Nice effluent. For the same samples virus concentrations obtained following glass powder adsorption method varied between 0 and 8.5 MPNCU/l (MGT 0.9 MPNCU/l) for the Cagnes effluent and between 0 and 25.5 MPNCU/l (MOT= 1.3 MPNCU/l1) for the Nice effluent. This difference is statistically significant (p = 0.0119 for the Cagnes effluent and p < 0.0001 for the Nice effluent). Furthermore, when taking into account the origin of the waters analysed, comparison between observed F0.95 (7.94 for the Cagnes waters and 45.78 for the Nice waters) and theoretical F0.95 (4.75 for the Cagnes waters and 4.45 for the Nice waters) leads to the rejection of the hypothesis of identity of the two methods. The discordances observed are an illustration of the fact that concluding to the absence of viruses in a given sample is a matter of method and should be interpreted with prudence. A few drawbacks inherent to the glass powder adsorption method may explain its poorer efficiency : the necessary acidification of the sample to pH 3.5 may be fatal to a proportion of virions; also the flow rate necessary to maintain the fluid layer of glass powder in suspension during the adsorption step is 6 fold higher than that required in the glass wool method (60 l/h vs 10 l/h). Finally the nature of the adsorbing material, sodocalcic vs borosilicated, may be determinent. We can conclude from the present comparative study, to the statistically significant superiority of the glass wool method for virus concentration from treated waste waters

Vertebral infections caused by Haemophilus aphrophilus: case report and review

ObjectiveTo review in detail clinical presentation, bacteriologic findings, associated conditions and treatment of Haemophilus aphrophilus vertebral osteomyelitis and to compare them to a case we report herein.MethodsA Medline (National Library of Medicine) search of the literature was performed by using the key words H. aphrophilus, spondylodiscitis, discitis, and vertebral osteomyelitis. The references of the case reports were examined for additional cases, especially those cited in older articles that had not been entered onto the bibliographic database.ResultsA case report of spondylodiscitis due to H. aphrophilus in a 35-year-old patient with a history of dental abscess 7 months before admission is presented. The patient responded well to treatment with ceftriaxone and ciprofloxacin. To date, only 14 cases of H. aphrophilus vertebral osteomyelitis have been reported. They are usually reported in middle-aged patients, usually male. Most recent cases have been treated with fluoroquinolones. Duration of treatment usually ranges from 1 to 3 months.ConclusionsH. aphrophilus is an uncommon cause of vertebral osteomyelitis. Patients are regularly cured by antibiotic therapy, provided that a tissue biopsy is performed in order to isolate the causative bacterium

Lo statuto della donna nelle novelle fiorentine del Rinascimento; tra realismo e realtà storica

Le genre de la nouvelle s'épuise au XVIe siècle lorsque les écrivains - comme Firenzuola et Grazzini (surtout le deuxième) - tout en suivant le modèle de Boccace dans leurs recueils respectifs, essaient cependant de s'en émanciper. L'image de la femme (souvent protagoniste des récits) qui y est dépeinte, est en contraste avec la réalité historique. Émerge au contraire, un portrait de la femme - dans ses rôles respectifs (femme, mère, amante...) à la fois ambigu et subversif. Sans s'encombrer de scrupules, elle cherche à s'approprier - dans une organisation sociale qui veut à tout prix la contenir - un espace de liberté et d'autonomie.Il genere della novella si esaurisce nel XVI secolo quando gli scrittori - tali Firenzuola e Grazzini, mettendosi sulla scia di Boccaccio (soprattutto il secondo), provano tuttavia nelle loro rispettive raccolte, di emanciparsene. Della donna, spesso protagonista dei racconti, vi è data un'immagine contrastante rispetto alla realtà storica. Emerge invece, un ritratto della donna - nei suoi rispettivi ruoli (moglie, madre, amante,...), molto ambiguo e insieme sovversivo. A dispetto di scrupoli, cerca di appropriarsi - in un'organizzazione sociale maschilista che la vuole contenere a tutti i costi - uno spazio di libertà e la propria autonomia

Influencia de la guitarra española en la música panameña

La presente tesis, "Influencia de la Guitarra Española en la música panameña", aspira a ser un documento de pnmera mano, que le ofrezca a futuros investigadores, escritores y estudiosos de la guitarra clásica, las luces necesarias para lograr entender el verdadero logro que se ha alcanzado en Panama desde 1941, fecha en que llega a Panamá, Manuel López Mi investigación abarca desde los Inicios de los instrumentos que se tañían con la punta de los dedos, como la cítara griega, hasta la metamorfosis que ha sufrido la guitarra para llamarse propiamente, guitarra, tanto estructural como etimológicamente En este trabajo, he guando destacar a la guitarra barroca del siglo XVIl,-que tuvo un gran desarrollo técnico en su momento y una recesión en el siglo XVIII, para luego lograr un gran resurgimiento que se da en el siglo XIX a través de grandes obras y destacados guitarristas He realizado un esfuerzo Importante en destacar a los compositores y guitarristas panameños desde 1941 hasta nuestros días, y he podido lograr evaluar el desarrollo técnico y artistico que se ha logrado hasta hoy He demostrado con recursos visuales las partes estructurales de la guitarra y además he explicado sus características sonoras Concientemente he investigado las diferentes escuelas de la guitarra a nivel mundial y sus pnncipios técnicos y como consecuencia he podido encontrar los nombres de las figuras más relevantes de la guitarra contemporánea Fue importante en el presente trabajo desarrollar un capitulo concerniente a la guitarra nacional de Panama — la mejoranera- sobre su música, su técnica, sus artistas, y me senil honrado al utilizar el libro "El Maestro" de mi compatriota Juan Andres Castillo de oriundo de Chare El final de este trabajo de investigacion se ha centrado en las diferentes escuelas de musica, tanto gubernamentales como privadas que han promovido la enseñanza de la guitarra clásica en Panamá, a la vez, de promover planes de estudios acordes con paises de gran desarrollo guitarrístico como lo son Argentina, Uruguay, Chile, Brasil, México, Venezuela y Cuba Le agradezco a Dios por haberme permitido poner mi granito de arena dentro de la historia y desarrollo de la guitarra en Panamá

Diseño de espacios comunes y paisajísticos para unidades vecinales.

Introducción: Cada vez, es mayor el número de estudios que resaltan los beneficios ambientales y sociales de las zonas verdes paisajísticas dentro de áreas comunes para mitigar los efectos ambientales inducidos por la Urbanización y el desmedro de la de calidad de vida de los ciudadanos. Sin embargo, la relación entre el bienestar y los espacios verdes urbanos aún sigue sin tenerse en cuenta por los planificadores y tomadores de decisiones en la ciudad. El concepto de urbanización debe proceder a una evolución más equilibrada en el desarrollo sostenible urbano, que tenga en cuenta a los residentes de la ciudad y su calidad de vida. Con este estudio, inicialmente conoceremos el desafío de una ciudad que crece vertiginosamente y que experimenta los problemas que esto conlleva, disminuyendo cada vez más la importancia de espacios públicos y áreas verdes. Con este estudio podremos distinguir claramente la delimitación del área a trabajar en esta investigación. Posteriormente, nos adentraremos a una parte importante que corresponde a conocer las características de una urbanización y sus áreas vecinales, tanto como los requisitos legales en cuanto al porcentaje de áreas comunes que se requieren en un área urbana como lo es el lugar de estudio. Las áreas verdes no solo ofrecen ventajas paisajísticas sino que también implican otros beneficios ambientales como lo son la regulación de temperatura y control del exceso de viento que puede secar la tierra y dañar las plantas. Con estos temas planteados, pasamos a describir más particularmente las cualidades urbanísticas del lugar de estudio en la actualidad, en cuanto a la servidumbre existente, la condición de las cunetas, el tipo de grama que existe, la vegetación que se puede encontrar a fin de conocerla y aprovechar sus cualidades ya que el clima es particularmente árido y requiere de cierto tipo de vegetación. Pasamos luego, a describir cómo son los espacios comunes y paisajes encontrados en el sitio, y qué características en particular tienen, de manera que podamos adentrarnos más en lo que necesitaríamos para poder encaminar la investigación descriptiva. En cuanto a la arquitectura podremos conocer la influencia actual que mantienen las viviendas o edificaciones en general de este lugar y a partir de allí podremos ver la incorporación de Diseños Inteligentes y Ahorro energético mediante elementos como lo son el uso de paneles solares, aprovechamiento del viento y beneficios que podemos obtener del agua de lluvia mediante métodos específicos que así lo permitan. Luego nos adentraremos a una importante parte de la investigación que tiene que ver con el método de investigación y cómo será realizado el compendio de la información recogida para lograr tabularla adecuadamente. Una vez hecho esto, se procede a mostrar la propuesta y su debido análisis para poder apreciar sus características y poderlas identificar gráficamente. Finalmente, exploraremos diversas fichas técnicas acerca de los temas anteriormente expuestos que nos permiten conocer los materiales o tecnologías a emplearse y entender las bondades que nos ofrece su aplicación para las áreas comunes de dicha urbanización. (Gómez, 2015