Search results for " Stabilization"
showing 10 items of 84 documents
Effect of internal noise on the relaxation time of an yttria stabilized zirconia-based memristor
2022
The effects of temperature on the switching kinetics of an yttrium-stabilized zirconia-based memristor from a low-resistance state to a high-resistance state have been experimentally investigated. It was found that the memristor relaxation time depends on the temperature in a non-monotonous way, with a maximum observed at the temperature close to 55 °C. This nonmonotonic behavior is a signature of the noise-enhanced stability phenomenon observed in all physical and complex systems characterized by metastable states.
Influence of bacterial physiology on processing of selenite, biogenesis of nanomaterials and their thermodynamic stability
2019
We explored how Ochrobactrum sp. MPV1 can convert up to 2.5 mM selenite within 120 h, surviving the challenge posed by high oxyanion concentrations. The data show that thiol-based biotic chemical reaction(s) occur upon bacterial exposure to low selenite concentrations, whereas enzymatic systems account for oxyanion removal when 2 mM oxyanion is exceeded. The selenite bioprocessing produces selenium nanomaterials, whose size and morphology depend on the bacterial physiology. Selenium nanoparticles were always produced by MPV1 cells, featuring an average diameter ranging between 90 and 140 nm, which we conclude constitutes the thermodynamic stability range for these nanostructures. Alternativ…
<p><strong><em>Diversispora valentina</em></strong><strong> (Diversisporaceae), a new species of arbuscular mycor…
2020
A new arbuscular mycorrhizal fungal species, Diversispora valentina, is described and illustrated. In the field, this species is associated with marine dunes located along the Mediterranean coast in eastern Spain. Spores of D. valentina occurred in sporocarps, in clusters, and singly in the soil or inside the roots of Ammophila arenaria (Poaceae), Elymus farctus (Poaceae), Otanthus maritimus (Asteraceae), and Echinophora spinosa (Apiaceae) in the six locations studied. A single-species culture of D. valentina was obtained using Trifolium repens as a host plant. The small subunit internal transcribed spacer and large subunit (SSU-ITS1-5.8S-ITS2-LSU) nrDNA sequences place the new species in t…
Bottle microresonator with actively stabilized evanescent coupling
2011
The evanescent coupling of light between a whispering-gallery-mode bottle microresonator and a sub-wavelength-diameter coupling fiber is actively stabilized by means of a Pound-Drever-Hall technique. We demonstrate the stabilization of a critically coupled resonator with a control bandwidth of 0.1 Hz, yielding a residual transmission of (9 \pm 3) \times 10^-3 for more than an hour. Simultaneously, the frequency of the resonator mode is actively stabilized.
On the relations between aromaticity and substituent effect
2019
Aromaticity/aromatic and substituent/substituent effects belong to the most commonly used terms in organic chemistry and related fields. The quantitative description of aromaticity is based on energetic, geometric (e.g., HOMA), magnetic (e.g., NICS) and reactivity criteria, as well as the properties of the electronic structure (e.g., FLU). The substituent effect can be described using either traditional Hammett-type substituent constants or characteristics based on quantum-chemistry. For this purpose, the energies of properly designed homodesmotic reactions and electron density distribution are used. In the first case, a descriptor named SESE (energy stabilizing the substituent effect) is o…
A Fractional-Order Model of Biopolyester Containing Naturally Occurring Compounds for Soil Stabilization
2019
Currently, the use of polymers and biopolymers as soil-stabilizer additives for control of the soil degradation, deterioration, and desertification and for improving the arid and semiarid soils has been expanded significantly in the agricultural sector. This research was conducted to determine the effect of naturally occurring compounds, such as quercetin (Q) and sodium montmorillonite (NaMMt) at different weight ratios, in biopolyester, such as polylactic acid (PLA), aiming to formulate ecosustainable materials to control the soil degradation and to protect the environment. As known, the use of sophisticated analytical tools to describe the material rheology and melting properties is nowad…
tRNA stabilization by modified nucleotides.
2010
Post-transcriptional ribonucleotide modification is a phenomenon best studied in tRNA, where it occurs most frequently and in great chemical diversity. This paper reviews the intrinsic network of modifications in the structural core of the tRNA, which governs structural flexibility and rigidity to fine-tune the molecule to peak performance and to regulate its steady-state level. Structural effects of RNA modifications range from nanometer-scale rearrangements to subtle restrictions of conformational space on the angstrom scale. Structural stabilization resulting from nucleotide modification results in increased thermal stability and translates into protection against unspecific degradation …
Anti-/Pro-Oxidant Behavior of Naturally Occurring Molecules in Polymers and Biopolymers: A Brief Review
2019
Polymers and biopolymers are continuously subjected to the action of different stress factors, such as oxygen, heat, UV light, mechanical stress, humidity, etc., during their processing and service life, undergoing overall oxidative degradation, that causes performance and property deterioration. To improve the resistance at high temperatures and long-term weatherability of the polymers and biopolymers, usually, during their manufacturing, synthetic antioxidants and UV-light stabilizers are added. In the past decade, several concerns related to the impact of the synthetic stabilizers have emerged, and to reduce their negative effect on human health and the environment, their replacement wit…
Quercetin as natural stabilizing agent for bio-polymer
2014
The introduction of antioxidants in polymers is the main way to prevent or delay the degradation process. In particular natural antioxidants receive attention in the food industry also because of their presumed safety. In this work bio-polymers, i.e. a commercial starch-based polymer (Mater-Bi®) and a bio-polyester (PLA), and a bio-polyether (PEO) were additivated with quercetin, a natural flavonoid antioxidants, in order to formulate bio-based films for ecosustainable packaging and outdoor applications. The photo-oxidation behavior of unstabilized and quercetin stabilized films was analyzed and compared with the behavior of films additivated with a commercial synthetic light stabilizer. Th…
Melt stabilization of wet polyamide 6
2002
Abstract Melt processing of polycondensate polymers must be carried out after careful drying in order to avoid any hydrolytic chain scission caused by the presence of water or other small molecules. In this work, the effect of two different antioxidants on the processing and flow properties of a polyamide 6 sample not dried before processing operations has been studied. One of these stabilizers seems to protect the wet polymer from hydrolytic chain scission. This action has been interpreted considering that the stabilizer hydrolyses instead of the polyamide macromolecules.