Search results for "valency"
showing 10 items of 70 documents
Low-generation dendrimers with a calixarene core and based on a chiral C2-symmetric pyrrolidine as iminosugar mimics
2012
The preparation of low-generation dendrimers based on a simple calix[4]arene scaffold by insertion of the iminosugar-analogue C2-symmetric 3,4-dihydroxypyrrolidine is described. This methodology allows a rapid incorporation of a considerable number of iminosugar-like moieties in a reduced volume and in a well-defined geometry. The inclusion of alkali-metal ions (sodium and potassium) in the polar cavity defined by the acetamide moieties at the lower rim of the calixarene was demonstrated, which allows also the rigidification of the dendrimer structure and the iminosugar presentation in the clusters. The combination of the supramolecular properties of calixarenes with the advantage of a dend…
Clicked and long spaced galactosyl- and lactosylcalix[4]arenes: New multivalent galectin-3 ligands
2014
Four novel calix[4]arene-based glycoclusters were synthesized by conjugating the saccharide units to the macrocyclic scaffold using the CuAAC reaction and using long and hydrophilic ethylene glycol spacers. Initially, two galactosylcalix[4]arenes were prepared starting from saccharide units and calixarene cores which differ in the relative dispositions of the alkyne and azido groups. Once the most convenient synthetic pathway was selected, two further lactosylcalix[4]arenes were obtained, one in the cone, the other one in the 1,3-alternate structure. Preliminary studies of the interactions of these novel glycocalixarenes with galectin-3 were carried out by using a lectin-functionalized chip…
Multivalent ion-exchange model of biopolymer chromatography for mass overload conditions
1991
Abstract The simple model of multivalent ion-exchange biopolymer chromatography is analyzed on the basis of classical quasi-chemical temperature. The rigorous isotherm equation deduced from the stoichiometric displacement model (SDM) was used to stimulate the migration of a solute through the chromatographic column in the isocratic and gradient elution modes. The peak profiles generated for various sample sizes were compared with those obtained on the basis of a Langmuir isotherm. Peak tailing increases with the value of the exponent Z, defined as the ratio of the protein valency to the displacing counter-ion valency. For large Z the asymmetries due to the non-linearity of the isotherm are …
Efficient Self-Assembly of Di-, Tri-, Tetra-, and Hexavalent Hosts with Predefined Geometries for the Investigation of Multivalency
2015
Coordination-driven self-assembly of differently shaped di- to hexavalent crown-ether host molecules is described. A series of [21]crown-7- and [24]crown-8-substituted bipyridine and terpyridine ligands was synthetized in a "toolbox" approach. Subsequent coordination to 3d transition metal and ruthenium(II) ions provides an easy and fast access to host assemblies with variable valency and pre-defined orientations of the crown-ether moieties. Preliminary isothermal calorimetry (ITC) titrations provided promising results, which indicated the host complexes under study to be suitable for the future investigation of multivalent and cooperative binding. The hosts described herein will also be su…
La linguistica vista dalle Alpi. Teoria, lessicografia e multilinguismo
2019
Il volume raccoglie contributi che hanno come principale tema di ricerca la multiforme realtà linguistica dell’ambiente alpino. Essi indagano fenomeni linguistici di lingue standard e di minoranza appartenenti ai gruppi romanzo e germanico. Il libro si compone di quatto sezioni: modelli teorici, valenza e lessicografia, linguistica delle varietà e multilinguismo e le lingue nel Trentino-Alto Adige. The contributions of this book deal with the diverse linguistic situation of the Alps by focusing on phenomena of standard and minority languages which belong to the Romance and Germanic group. They address four main topics which correspond to the four sections of the book: linguistic theory, val…
Population analysis of pair densities. A study on cyclic systems
2000
Abstract Pair population analysis seems a reliable method for evaluating atomic valency states and bond orders from the MO wavefunction of molecular systems. A test on some cyclic organic systems was performed. The results confirm the capability of the method to provide a correct description of the molecules in terms of simple VB approach.
Efficacy, tolerability and influence on "quality of life" of nifedipine GITS versus amlodipine in elderly patients with mild-moderate hypertension.
2001
The main purpose of this study was to compare efficacy, tolerability and influence on quality of life (QOL) of nifedipine gastrointestinal therapeutic system (NI) 30-60 mg once a day vs amlodipine (AM) 5-10 mg once a day in elderly patients with mild-moderate hypertension.This was a randomized, double-blind, parallel-group, multicenter study. After a 2-week single-blind placebo run-in, patients were randomized to either NI 30 mg or AM 5 mg. Responders continued on the same dosage for 16 additional weeks, while non-responders were titrated to 60 mg NI or 10 mg AM.Blood pressure was measured by mercury sphygmomanometer and efficacy equivalence of NI and AM tested by covariance analysis. Diast…
Valenza e insegnamento della lingua straniera
2015
This work deals with valency, a key syntactic notion whose chemistry-inspired label was established by Lucien Tesnière (1959), one of the most well-known contributors to the Prague Linguistic Circle. We will concentrate on two questions: (a) to what extent does valency play a role in Second Language Learning (SLL)?; and (b) what role should the use of valency play in language teaching practices? This paper will provide answers to these questions and propose reasons for motivating the use of valency in SLL.
The Scope of Application of Macrocyclic Polyamines Beyond Metal Chelation
2019
International audience; Recent advances in the use of radiometals for both imaging and therapy has spurred on the development of an original chemistry that endows radionuclide-chelating molecular cages with ever sharper physicochemical properties. Macrocyclic polyamines (MPAs) such as cyclen and DOTA are among the most frequently encountered cages for the design of new radiotracers, owing to their versatile chemistry that makes them customizable molecular tools. The idea of using MPAs for alternative purposes has recently emerged, with an eye towards benefiting from their unique topology, versatility, symmetry and water-solubility. This review summarizes strategies that have been recently i…
Autobiographical texts written by learners of Catalan as an Additional Language: From formative needs to reflection in the teaching of narrative genr…
2022
In this article we analyse autobiographical narrative texts written by university students studying Catalan as an Additional Language at a CEFR (2020) B1 level. The goal is to analyse the formative needs related to the writing of this genre in order to foster metadiscursive reflection in the classroom that will allow students to improve their written output. To this end, we analyzed a corpus of 39 autobiographies at both the macrotextual level (i.e., rhetorical moves) and the microtextual level (i.e., deictic elements which channel the narrative’s organization). Our results show that the problems that these texts present for students are related to awareness of the elements that define the …