Search results for "amine"
showing 10 items of 7299 documents
Interaction ofEscherichia colihemolysin with biological membranes
2001
Escherichia coli hemolysin (HlyA) is a membrane-permeabilizing protein belonging to the family of RTX-toxins. Lytic activity depends on binding of Ca2(+) to the C-terminus of the molecule. The N-terminus of HlyA harbors hydrophobic sequences that are believed to constitute the membrane-inserting domain. In this study, 13 HlyA cysteine-replacement mutants were constructed and labeled with the polarity-sensitive fluorescent probe 6-bromoacetyl-2-dimethylaminonaphthalene (badan). The fluorescence emission of the label was examined in soluble and membrane-bound toxin. Binding effected a major blue shift in the emission of six residues within the N-terminal hydrophobic domain, indicating inserti…
Molecular architecture of a toxin pore: a 15-residue sequence lines the transmembrane channel of staphylococcal alpha-toxin.
1996
Staphylococcus aureus alpha-toxin is a hydrophilic polypeptide of 293 amino acids that produces heptameric transmembrane pores. During assembly, the formation of a pre-pore precedes membrane permeabilization; the latter is linked to a conformational change in the oligomer. Here, 41 single-cysteine replacement toxin mutants were thiol-specifically labelled with the polarity-sensitive fluorescent probe acrylodan. After oligomerization on membranes, only the mutants with acrylodan attached to residues in the sequence 118-140 exhibited a marked blue shift in the fluorescence emission maximum, indicative of movement of the fluorophore to a hydrophobic environment. Within this region, two functio…
Effect of river restoration on life-history strategies in fish communities
2019
Assessments of river restoration outcomes are mostly based on taxonomic identities of species, which may not be optimal because a direct relationship to river functions remains obscure and results are hardly comparable across biogeographic borders. The use of ecological species trait information instead of taxonomic units may help to overcome these challenges. Abundance data for fish communities were gathered from 134 river restoration projects conducted in Switzerland, Germany and Finland, monitored for up to 15 years. These data were related to a dataset of 22 categories of ecological traits describing fish life-history strategies to assess the outcome of the restoration projects. Restora…
Solid state NMR investigation of the roman Acqualadroni rostrum: tenth year assessment of the consolidation treatment of the wooden part
2020
Abstract: This work follows a previous one dealing with the state of conservation study of the wooden part of the roman Acqualadroni rostrum soon after its finding in the seabed of Acqualadroni (Messina, Italy). The archaeological survey and recovery were particularly relevant since this artefact is one of the two rostrums, nowadays known,found together with its wooden part. Following the recovery, it was consolidated by immersion in a melamine-formaldehyde resin (Kauramin) aqueous solution for eight months at the “Centro di Restauro del Legno Bagnato” (Pisa, Italy). The present investigation is aimed to determine at microscopic scale the wood state of conservation and to highlight interact…
Spelling in Finnish : the case of the double consonant
2021
Because of its regularity, it is relatively easy to learn to read and spell in Finnish. However, a specific hurdle in spelling acquisition seems to be the doubling of consonant letters. In this study on consonant letter doubling spelling in Finnish children (91 Grade 1 and 191 Grade 2 children), we asked two questions. First, are items with double consonant letters (e.g., “kissa” [ˈkisːɑ] ‘cat’) indeed harder to spell than single consonant items (e.g., “kisa” [ˈkisɑ] ‘contest’)? Second, is consonant doubling harder for stop consonants (e.g., “takki” [ˈtɑkːi] ‘coat’) than for continuant consonants (e.g., “kissa&rdq…
Dynamic analysis for axially moving viscoelastic panels
2012
In this study, stability and dynamic behaviour of axially moving viscoelastic panels are investigated with the help of the classical modal analysis. We use the flat panel theory combined with the Kelvin–Voigt viscoelastic constitutive model, and we include the material derivative in the viscoelastic relations. Complex eigenvalues for the moving viscoelastic panel are studied with respect to the panel velocity, and the corresponding eigenfunctions are found using central finite differences. The governing equation for the transverse displacement of the panel is of fifth order in space, and thus five boundary conditions are set for the problem. The fifth condition is derived and set at the in-…
Comparison of Hybrid Blends for Solar Cell Application
2010
In blended hybrid systems distinct micro- or nanostructured materials can be formed by phase separation. Network structures of particles or rods in a polymer matrix can be developed via self-assembly. We use this blending approach to compare active materials for application in solar cell devices. Blends were fabricated from either poly(hexylthiophene) P3HT or poly(triphenylamine) PTPA mixed with nanocrystalline TiO 2 rods. In this manner, we compare two different hole conducting polymers in their performance in photovoltaic devices, while experimental conditions are kept identical. We find that the choice of solvent and photovoltaic characterization conducted in inert atmosphere is of impor…
Optimistic NAUTILUS navigator for multiobjective optimization with costly function evaluations
2022
AbstractWe introduce novel concepts to solve multiobjective optimization problems involving (computationally) expensive function evaluations and propose a new interactive method called O-NAUTILUS. It combines ideas of trade-off free search and navigation (where a decision maker sees changes in objective function values in real time) and extends the NAUTILUS Navigator method to surrogate-assisted optimization. Importantly, it utilizes uncertainty quantification from surrogate models like Kriging or properties like Lipschitz continuity to approximate a so-called optimistic Pareto optimal set. This enables the decision maker to search in unexplored parts of the Pareto optimal set and requires …
Scripting as a pedagogical method to guide collaborative writing : university students' reflections
2020
A collaboration script is a set of instructions used to improve collaborative learning among students in technology-enhanced environments. Previously, university students’ perspective has been under-represented in the study on collaboration scripts. In this article, we focus on understanding students’ experiences in a scripted collaborative writing task, especially from the perspective of following the script. The study was conducted among undergraduate students (N = 91) taking a master-level educational science course at one university each in Finland and Belgium. Divided into 25 groups, each with three to five members, the students worked on collaborative writing tasks. During their share…
A new ferromagnetically coupled μ-alkoxo–μ-acetato copper(II) trinuclear complex: [Cu3(H2tea)(Htea)(CH3COO)2](ClO4) (H3tea=triethanolamine)
2005
Abstract A μ-alkoxo–μ-acetato trinuclear copper(II) complex, [Cu3(H2tea)(Htea)(CH3COO)2](ClO4) 1, has been synthesized by reacting copper(II) perchlorate, triethanolamine and sodium acetate. The unit cell contains two centrosymmetric, crystallographically independent trinuclear Cu(II) complexes and two ClO 4 - ions. The crystallographically independent trinuclear Cu(II) complexes differ mainly in some of their geometry parameters. The coordination environment of the central copper atom is square-planar, in one trinuclear entity, and elongated octahedral in the other one (in this last case, the coordination number of the central copper atom increases through the semicoordination of an oxygen…