Search results for "Sodium"
showing 10 items of 1605 documents
Elektrophysiologische Untersuchung zum Einsatz von Streptolysin O und Natrium-Hyaluronat zur Permeabilitätsmodulation der Membran des runden Fensters…
2003
Background: The round window membrane (RWM) acts like a barrier for topically applied substances into the middle ear preventing diffusion into the perilymphatic fluid compartment. Material and Method: In an animal model, modulation of the permeability of the RWM was attempted using Streptolysin-O (SLO) in various concentrations and sodium hyaluronate. Thereafter, the effect of intratympanically applied Lidocain 2% on hearing threshold measured by auditory brainstem response was tested for Lidocain 2 % and Lidocain 2 % in combination with SLO or sodium hyaluronate. Results: The results show that both, SLO and sodium hyaluronate, influence the effect of Lidocain 2 % on hearing thresholds as a…
Hybrid layers of etch-and-rinse versus self-etching adhesive systems.
2010
Objective: To evaluate the effectiveness in the formation of resin tags, adhesive lateral branches and hybrid layers of five adhesive systems, when bonding to dentine. Material and Methods: Flat dentin surfaces from 25 molars were bonded with several adhesive systems according to the manufacturers? instructions. Composite build-ups were constructed incrementally with Tetric Ceram. The Specimens were sectioned parallel to the long axis. One section was treated with phosphoric acid and sodium hypochlorite in order to reveal the hybrid layer formation. The other section was stored in 30% hydrochloric acid to detect resin tags and adhesive lateral branch formation. Results: The two etch-and-rin…
DNA-binding of zinc(II) and nickel(II) salphen-like complexes extrapolated at 1 M salt concentration: Removing the ionic strength bias in physiologic…
2020
Abstract The DNA-binding of two salphen-like metal complexes of nickel(II) (1) and zinc(II) (2) was investigated in different ionic strength solutions by absorption spectroscopy. The data analysis allowed us to obtain the values of their extrapolated DNA-binding constant in physiological conditions, with DNA-binding strength in the order Ni > Zn, and to give relative weight to the electrostatic and non-electrostatic contributions to their DNA-interaction.
Ag11(SG)7 : A New Cluster Identified by Mass Spectrometry and Optical Spectroscopy
2014
We report a one-step and high yield synthesis of a red-luminescent silver cluster with the molecular formula, Ag11(SG)7 (SG: glutathionate) via reduction of silver ions by sodium borohydride in the presence of the tripeptide, glutathione (GSH). The as-prepared cluster shows prominent absorption features at 485 and 625 nm in its UV-vis absorption spectrum. Aging of the as-prepared cluster solution led to the disappearance of the 625 nm peak, followed by broadening of the 485 nm peak to give three maxima at ?487, 437, and 393 nm in its absorption spectrum. These peaks remain unchanged even after polyacrylamide gel electrophoresis (PAGE), where a single band was observed confirming high purity…
Effect of short-chain alcohols on surfactant-mediated reversed-phase liquid chromatographic systems.
2010
The behaviour of β-blockers in a reversed-phase liquid chromatographic (RPLC) column with mobile phases containing a short-chain alcohol (methanol, ethanol or 1-propanol), with and without the surfactant sodium dodecyl sulphate (SDS), was explored. Two surfactant-mediated RPLC modes were studied, where the mobile phases contained either micelles or only surfactant monomers at high concentration. Acetonitrile was also considered for comparison purposes. A correlation was found between the effects of the organic solvent on micelle formation (monitored by the drop weight procedure) and on the nature of the chromatographic system (as revealed by the retention, elution strength and peak shape of…
Submicellar and micellar reversed-phase liquid chromatographic modes applied to the separation of beta-blockers.
2009
The behaviour of a reversed-phase liquid chromatographic (RPLC) system (i.e. elution order, resolution and analysis time), used in the analysis of β-blockers with acetonitrile-water mobile phases, changes drastically upon addition of an anionic surfactant (sodium dodecyl sulphate, SDS). Surfactant monomers cover the alkyl-bonded phase in different extent depending on the concentration of both modifiers, in the ranges 1 × 10-3-0.15 M SDS and 5-50% acetonitrile. Meanwhile, the surfactant is dissolved in the mobile phase as free monomers, associated in small clusters or forming micelles. Four characteristic RPLC modes are yielded, with transition regions between them: hydro-organic, micellar, …
Performance of different C18 columns in reversed-phase liquid chromatography with hydro-organic and micellar-organic mobile phases
2014
Column selection in reversed-phase liquid chromatography (RPLC) can become a challenge if the target compounds interact with the silica-based packing. One of such interactions is the attraction of cationic solutes to the free silanols in silica-based columns, which is a slow sorption-desorption interaction process that gives rise to tailed and broad peaks. The effect of silanols is minimised by the addition of a competing agent in the mobile phase, such as the anionic surfactant sodium dodecyl sulphate (SDS). In micellar-organic RPLC, the adsorption of an approximately fixed amount of SDS monomers gives rise to a stable modified stationary phase, with properties remarkably different from th…
Prediction of peak shape in hydro-organic and micellar-organic liquid chromatography as a function of mobile phase composition
2007
A simple model is proposed that relates the parameters describing the peak width with the retention time, which can be easily predicted as a function of mobile phase composition. This allows the further prediction of peak shape with global errors below 5%, using a modified Gaussian model with a parabolic variance. The model is useful in the optimisation of chromatographic resolution to assess an eventual overlapping of close peaks. The dependence of peak shape with mobile phase composition was studied for mobile phases containing acetonitrile in the presence and absence of micellised surfactant (micellar-organic and hydro-organic reversed-phase liquid chromatography, RPLC). In micellar RPLC…
Peak half-width plots to study the effect of organic solvents on the peak performance of basic drugs in micellar liquid chromatography.
2009
The addition of the anionic surfactant sodium dodecyl sulphate (SDS) to hydro-organic mixtures of methanol, ethanol, propanol or acetonitrile with water yielded enhanced peak shape (i.e. increased efficiencies and symmetrical peaks) for a group of basic drugs (β-blockers) chromatographed with a Kromasil C18 column. The effect can be explained by the thin layer of surfactant associated to the hydrocarbon chain on the stationary phase in the presence of the organic solvents, which covers the free silanols on the siliceous support avoiding their interaction with the cationic basic drugs. These instead interact with the anionic head of the surfactant increasing their retention and allowing a mo…
Hydration of calcium sulfate hemihydrate (CaSO4·H2O) into gypsum (CaSO4·2H2O). The influence of the sodium poly(acrylate)/surface interaction and mol…
2000
Abstract The retarding influence of sodium poly(acrylate) (PANa) on the hydration of calcium sulfate hemihydrate (CaSO 4 · 1 2 H 2 O) was investigated. This study reports the influence of sodium poly(acrylate) on hemihydrate dissolution, on homogenous and heterogeneous gypsum (CaSO 4 ·2H 2 O) nucleation as well as on gypsum growth. It is shown that adsorption of PANa does not hinder the dissolution of hemihydrate in the present experimental conditions. The specific interaction of PANa with gypsum can explain the oriented growth of gypsum crystal. The gypsum growth is slowed down but cannot be blocked by the adsorption of PANa. On the other hand, PANa can block the heterogeneous and homogeno…