Polymeric neoglycoconjugates: Synthesis, characterization and properties

As part of a currently intense research effort into the development of novel potent macromolecular pharmaceuticals, diagnostic tools and carriers for targeted drug delivery, this project involved the synthesis of glycopolymers. Polymethacrylate derivatives carrying carbohydrate residues were efficiently prepared in a stereo-controlled manner, following two different routes. As revealed by a thorough characterisation of the materials obtained, the synthetic procedure strongly affected the polymers' composition and, in turn, their properties, such as their self-association in aqueous media and the interaction of the compounds bearing D-galactose units with a specific lectin. Polymers containing peracetylated saccharide residues were shown to be surface-active, forming stable spread Langmuir films. These monolayers acted as effective dl-aspartic acid nucleation promoters, whilst the soluble analogues (for which the sugars are deacetylated) seemed to possess a certain activity as dl-aspartic acid growth inhibitors.The behaviour of the deprotected polymers in aqueous solution was thoroughly investigated, prior to testing whether the materials carrying galactosyl units on the side chains could be recognised by a galactose-specific protein. For the first time for polymeric glycoconjugates, thermodynamic binding parameters relative to this protein-carbohydrate interaction were directly evaluated using isothermal titration microcalorimetry

Lernstrategien zum Erwerb des Englischen als Fremdsprache auf verschiedenen Altersstufen

Learning strategies are procedures or techniques that learners can use to facilitate a learning task. While some learning strategies are observable, most strategies are mental processes that are not directly observable. The investigation of personality factors is often mentioned to be important for gaining deeper insights into learning strategies. In this article we discuss the relationship between personality factors such as language anxiety, self-concept, previously achieved language learning experience and language learning strategies in different EFL education levels. A total of 833 Croatian learners took part in this exploratory study: 330 primary school learners, 309 secondary school learners and 194 university undergraduates. All the subjects learned EFL as a compulsory school subject or university course. Four instruments were used for this study: language learning anxiety, self-concept, previously achieved language learning experience, and use of language learning strategies. The One-way Analysis of Variance indicated that the mean of the scores regarding the use of learning strategies significantly differ among the three groups. Furthermore, the results indicated that there was a significant relation between language anxiety, self-concept and previously achieved language learning experience with language learning strategies.Lernstrategien bestehen in Verfahren oder Techniken, die Schülern das Lernen erleichtern sollen. Während einzelne Strategien bewusst unternommen und sichtbar werden, spielen sich andere als von außen unsichtbare mentale Vorgänge ab. Wichtig sind dabei Erkenntnisse aus der Persönlichkeitspsychologie, da sie einen tieferen Einblick in mögliche Lernstrategien ermöglichen. Die Verfasserinnen sprechen in ihrem Artikel über den Bezug zwischen bestimmten persönlichen Einstellungen wie Angst vor dem Sprachunterricht, Einstellung zu sich selbst als Lernsubjekt (akademischer Ich-Begriff), früheren Erfahrungen mit dem Sprachenlernen einerseits und Strategien zum Erwerb des Englischen als Fremdsprache (auf verschiedenen Lernstufen) andererseits. An der Untersuchung nahmen 883 kroatische Schüler teil: 330 Grundschüler,* 309 Mittelschüler und Gymnasiasten sowie 194 Studenten. Sämtliche Untersuchungsteilnehmer lernten Englisch als Fremdsprache. Bei der Untersuchung kamen vier Untersuchungsinstrumente zum Einsatz. Ermittelt wurden: die Angst vor dem Fremdsprachenunterricht, die Einstellung zu sich selbst als Lernsubjekt (akademischer Ich-Begriff), frühere Erfahrungen mit dem Sprachenlernen und der Einsatz von Lernstrategien zum besseren Spracherwerb. Die Ergebnisse der Varianzanalyse zeigen, dass sich die Untersuchungsteilnehmergruppen hinsichtlich der von ihnen benutzten Lernstrategien wesentlich voneinander unterscheiden. Zu erkennen ist ein relevanter Zusammenhang zwischen bestimmten persönlichen Einstellungen (Angst vor dem Fremdsprachenunterricht, akademischer Ich-Begriff und frühere Erfahrungen mit dem Sprachenlernen) und dem Einsatz von Lernstrategien zum besseren Erwerb des Englischen als Fremdsprache

Understanding the formation of efflorescence on beeswax models housed at the Natural History Museum of Florence

The Natural History Museum of Florence, and in particular “La Specola”, houses several ceroplastics collections produced in Florence in the XVIII-XIX centuries by Clemente Susini and co-workers. The collections include models of fruits and plants, vertebrate and invertebrate animals, and over 1400 anatomical waxes. All models are mainly constituted by beeswax. Although extremely resistant, the models undergo a wide range of degradation processes. Periodically, a white crystalline efflorescence, commonly called “wax bloom”, appears on the surface of the objects obviously impairing their aesthetical features. Many mechanisms have been hypothesized about the formation of these white exudates, but non univocal conclusions have yet been drawn. Our gas chromatography-mass spectrometry results indicate that wax bloom strongly depends on the composition of the models, being related to the presence of oils and fats originally used as plasticizers or pigments’ media. Thermal and X-ray measurements indicate that a poor solid-solid miscibility between the efflorescence compounds and other beeswax components leads to phase separation followed by migration of the immiscible materials towards the model surface. Besides, X-ray diffraction reveals an increased structural order of models as compared to recent beeswax certainly correlated with the increased brittleness determined by rheology measurements.This work was supported by Fondazione Cassa di Risparmio di Firenze through the funding of the joint project “Approccio innovativo nanotecnologico per la conservazione delle cere anatomiche della Sezione di Zoologia “La Specola” del Museo di Storia Naturale dell'Università degli Studi di Firenze”, aimed at setting up a novel, nanotechnology-based approach for the conservation of the anatomical wax models.Departamento de Ingeniería Química, Química Física y Ciencias de los Materiale

The curious effect of potassium fluoride on glycerol carbonate. How salts can influence the structuredness of organic solvents

Glycerol carbonate (4-hydroxymethyl-1,3-dioxolan-2-one, shortly GC) is a dense, viscous, water soluble solvent. The high dielectric constant and dipole moment make it a suitable non-aqueous green solvent for several salts in different applications. GC dissolves significant amounts of inorganic salts such as KF. The saturation of GC with KF leads to the formation of a viscous liquid at room temperature. In this paper, we report on conductivity, rheology, differential scanning calorimetry and infrared spectroscopy experiments that indicate the formation of a glassy liquid where GC molecules and KF ion pairs are intercalated in a firm and ordered tridimensional structure, stabilized by hydrogen bonding and strong ion-dipole interactions

Phase transitions in hydrophobe/phospholipid mixtures: hints at connections between pheromones and anaesthetic activity

The phase behavior of a mixture of a typical insect pheromone (olean) and a phospholipid (DOPC)/water dispersion is extensively explored through SAXS, NMR and DSC experiments. The results mimic those obtained with anaesthetics in phospholipid/water systems. They also mimic the behavior and microstructure of ternary mixtures of a membrane mimetic, bilayer-forming double chained surfactants, oils and water. Taken together with recent models for conduction of the nervous impulse, all hint at lipid involvement and the underlying unity in mechanisms of pheromone, anaesthetic and hydrophobic drugs, where a local phase change in the lipid membrane architecture may be at least partly involved in the transmission of the signal