Search results for "Elongation"

Processing and characterization of highly oriented fibres of biodegradable nanocomposites

2015

Abstract Biodegradable polymeric materials are becoming day by day ever more important in packaging, agriculture, single-use cutleries and other large consumer applications. The major part of those materials is used under the form of film, i.e. subjected to elongational flow, but the main problem is that they often offer poor mechanical properties. Adding nanofillers, like Multi Walled Carbon Nanotubes (MWCNTs) may solve this problem but only if there is a full control of their orientation inside the material. Aim of this work is to investigate the processing-properties-morphology relationships for a system prepared under elongation flow of MaterBi and commercial MWCNTs. The materials were …

Corrigendum to “External conditions inversely change the RNA polymerase II elongation rate and density in yeast” [Biochim. Biophys. Acta 1829/11 (201…

2017

Regulon-Specific Control of Transcription Elongation across the Yeast Genome

2009

Transcription elongation by RNA polymerase II was often considered an invariant non-regulated process. However, genome-wide studies have shown that transcriptional pausing during elongation is a frequent phenomenon in tightly-regulated metazoan genes. Using a combination of ChIP-on-chip and genomic run-on approaches, we found that the proportion of transcriptionally active RNA polymerase II (active versus total) present throughout the yeast genome is characteristic of some functional gene classes, like those related to ribosomes and mitochondria. This proportion also responds to regulatory stimuli mediated by protein kinase A and, in relation to cytosolic ribosomal-protein genes, it is medi…

Combination of molecular data support the existence of three main lineages in the phylogeny of aphids (Hemiptera: Aphididae) and the basal position o…

2010

Abstract The first molecular studies on the phylogeny of aphids (Hemiptera: Aphididae) bumped into a striking lack of phylogenetic structure for taxa levels higher than tribe, probably as a consequence of the rapid adaptive radiation that this group of insects went through during the Late Cretaceous. Here we present a new attempt to infer the relationships between major aphid taxa by the separate and combined analysis of two nuclear sequences (the long-wavelength opsin gene and the elongation factor 1α gene) and two mitochondrial sequences (the genes encoding the subunit 6 of the F-ATPase and the subunit II of the cytochrome oxidase). Our results confirm previous results with the grouping o…

Chemical composition and phytotoxic effects of essential oils of Salvia hierosolymitana Boiss. and Salvia multicaulis Vahl. var. simplicifolia Boiss.…

2009

The chemical composition of the essential oils of S. hierosolymitana Boiss. and S. multicaulis Vahl. var. simplicifolia Boiss. collected in Lebanon was studied by means of GC and GC-MS analysis. In all 115 compounds were identified: 82 for S hierosolymitana and 72 for S. multicaulis var. simplicifolia. The presence of carbonylic compounds (17%) characterizes the oil from S. hierosolymitana, while S. multicaulis var. simplicifolia oil is rich of monoterpenes (34.5%) and sesquiterpenes (46.9%). The effects of the essential oils on germination and initial radical elongation of Raphanus sativus L. (radish) and Lepidium sativum L. (garden cress) were studied, indicating in a different activity a…

Lattice distortion of hcp solid helium under pressure

2009

The lattice distortion of hcp solid He under pressure is calculated using semiempirical and first-principle approaches. While three-body forces tend to flatten the lattice at all compressions, the effect of pair forces changes from the flattening at small compression to elongation at large one. At large compressions, the lattice distortion due to the triple forces is more than twice as large as those due to pair forces and the lattice is slightly flattened. First-principles results show that over approximately fivefold compressions higher-order, many-body forces become important.

Effect of kind and content of organo-modified clay on properties of PET nanocomposites

2011

In this work we report the properties of nanocomposite based on PET with two different samples of organically modified montmorillonites. In particular, we studied the effect of the filler concentration on morphology, rheology, and mechanical performance, focusing our attention on the effect of the degradation phenomena of the clay modifiers. The results indicate that at low clay level the morphology achieved is mainly intercalated. On increasing the filler level, coalescence and/or bad defragmentation phenomena induce a coarser morphology, as confirmed by XRD, SEM, and TEM observations. When a more polar organic modifier is used to modify the clay, the particle adhesion and distribution is …

Positron Annihilation in Polycrystalline Metals Deformed by Uniaxial Tension

2005

Angular distributions of the positron annihilation quanta were measured for polycrystalline samples deformed by uniaxial tension up to difierent deformation degrees. The S parameter as a function of the W parameter was determined. The data obtained for samples elongated up to difierent elongation degrees indicate that in the proportionality and limited proportionality regions the changes in the physical properties of samples are governed mainly by generation of vacancies and formation and kinetics of transformations of vacancy clusters occurring flrst of all on the grains of monocrystallites. In the region of plastic deformations the dominant defects are dislocations and vacancies and their…

Protofibril formation of amyloid beta-protein at low pH via a non-cooperative elongation mechanism.

2005

Deposition of the amyloid beta-protein (Abeta) in senile or diffuse plaques is a distinctive feature of Alzheimer's disease. The role of Abeta aggregates in the etiology of the disease is still controversial. The formation of linear aggregates, known as amyloid fibrils, has been proposed as the onset and the cause of pathological deposition. Yet, recent findings suggest that a more crucial role is played by prefibrillar oligomeric assemblies of Abeta that are highly toxic in the extracellular environment. In the present work, the mechanism of protofibril formation is studied at pH 3.1, starting from a solution of oligomeric precursors. By combining static light scattering and photon correla…

Enhancement of premature stop codon readthrough in the CFTR gene by Ataluren (PTC124) derivatives.

2015

Abstract Premature stop codons are the result of nonsense mutations occurring within the coding sequence of a gene. These mutations lead to the synthesis of a truncated protein and are responsible for several genetic diseases. A potential pharmacological approach to treat these diseases is to promote the translational readthrough of premature stop codons by small molecules aiming to restore the full-length protein. The compound PTC124 (Ataluren) was reported to promote the readthrough of the premature UGA stop codon, although its activity was questioned. The potential interaction of PTC124 with mutated mRNA was recently suggested by molecular dynamics (MD) studies highlighting the importanc…