Search results for " potential"

Salt concentration and particle density dependence of electrophoretic mobilities of spherical colloids in aqueous suspension.

2007

Using laser Doppler velocimetry in the superheterodyne mode, we conducted a systematic study of the electrophoretic mobility of dispersions of small silica spheres (a=18 nm) suspended in water at different salinities and particle concentrations. The concentration of NaCl was varied from 40 microM up to 16 mM, while the particle concentrations were varied between 4.2x10(18) and 2.1x10(20) m-3. We find a decrease of mobility with increasing salt concentrations and an increase with increased particle number densities. The latter observation is not backed by the standard cell model of electrophoresis with Shilov-Zharkikh boundary conditions. Rather, if the experimental data are interpreted with…

Counterion transport numbers of poly(acrylic acid)-grafted porous ion-exchange membranes as determined from current step measurements

1997

Abstract The effect of an electric current on the concentration polarization of the external bathing solutions and the permselectivity of poly(acrylic acid)-grafted porous ion-exchange membranes has been studied. The experimental approach is based on the transient behavior of the total electric potential drop through the membrane cell when a current step is imposed from external nonpolarizable electrodes. When this voltage drop is recorded as a function of time, a transition time characteristic of each membrane system is obtained. From this time, the counterion transport number for the salt solution (KClH2O) in the membrane can be obtained. The theoretical modeling is based on the time-dep…

Xenograft rejection in marine sponges. Isolation and purification of an inhibitory aggregation factor from Geodia cydonium.

1981

In sponges there exists a graft rejection mechanism in which an inhibitory aggregation factor is involved. The inhibitory aggregation factor has been isolated from a culture medium containing dissociated cells of the sponge Geodia cydonium. Using ion-exchange and gel fractionation the factor was purified and shown to be electrophoretically pure. The factor has a molecular weight of 27000 and was characterized as a glycoprotein. The activity of the inhibitory aggregation factor was not affected by heat treatment, but treatment with trichloroacetic acid resulted in the irreversible loss of activity. The inhibitory aggregation factor affects the aggregation-factor-mediated reaggregation of dis…

Investigations Concerning the Correlation of COX-1 Inhibitory and Hydroxyl Radical Scavenging Activity

2008

The aim was to study the COX-1 inhibiting efficacy in context with hydroxyl radical scavenging properties of compounds bearing a carboxylic acid and ester function, respectively. In general, the acids are more potent radical scavengers than the corresponding esters but there is no clear correlation with their COX-1 inhibiting potencies. A feasible scavenging mechanism of carboxylic acids is discussed.

A Deeper Insight into the Postpolymerization Modification of Polypenta Fluorophenyl Methacrylates to Poly(N -(2-Hydroxypropyl) Methacrylamide)

2014

This work provides a detailed insight into the synthesis of N-(2-hydroxypropyl)methacrylamide (HPMA) polymers employing the activated ester approach. In this approach, polypenta fluorophenyl methacrylate (PFPMA)-activated ester polymers are synthesized by the reversible addition-fragmentation chain transfer (RAFT) polymerization and transferred into HPMA-based systems by the use of 2-hydroxypropylamine. To prove quantitative conversion in the absence of side reactions, special attention is devoted to investigate different reaction conditions by different analytical methods ((1) H, (19) F, inverse-gated (13) C NMR, and zeta potential measurements). Furthermore the influence of common solvent…

Critical adsorption of a single macromolecule in polymer brushes.

2014

The adsorption of long flexible macromolecules by polymer brush-coated surfaces is studied by molecular dynamics simulations and by calculations using density functional and self-consistent field theories. The case of repulsive interactions between the substrate surface and the monomers of both the brush polymers and the extra chains that can get absorbed into the brush is considered. Under good solvent conditions, critical absorption can occur, if the interaction between the monomers of the brush polymers and the extra chain is (weakly) attractive. It is shown that it is possible to map out the details of the critical absorption transition, if the chain length and/or the grafting density o…

0152 : Effects of connexin 43 inhibition on mitochondrial function in cardiac skinned fibers and isolated mitochondria

2015

Connexin 43 (Cx43) is a main component of intercellular gap junction channels in cardiomyocytes. The presence of Cx43 in heart mitochondria has been also reported, where it may participate in energy metabolism and protection against ischemia. Given the key role for mitochondria in pathogenesis of heart diseases, we examined how mitochondrial function could be altered in case of Cx43 pharmacological inhibition by carbenoxolone (CBX). Oxygen consumption rates under various substrate conditions were determined either in ventricles from pig hearts using saponin-permeabilized fibers, or in isolated mitochondria from rat hearts. Measurements of mitochondrial membrane potential (ΔΨ) and reactive o…

Hormone Effects on the Membrane Potential and on Sucrose-Induced Depolarization of Young <italic>Citrus</italic> Leaves

1992

Load-collapse-release cascades of amphiphilic guest molecules in charged dendronized polymers through spatial separation of noncovalent forces.

2012

The ability to pack guest molecules into charged dendronized polymers (denpols) and the possibility to release these guest molecules from subsequently densely aggregated denpols in a load-collapse-release cascade is described. Charged denpols, which constitute molecular objects with a persistent, well-defined envelope and interior, are capable of incorporating large amounts of amphiphilic guest molecules. Simultaneously, multivalent ions can coordinate to the surfaces of charged denpols, leading to counterion-induced aggregation of the already guest-loaded host structures. Thus, although the local guest concentration in denpol-based molecular transport might already be initially high due to…

Tyramine action on motoneuron excitability and adaptable tyramine/octopamine ratios adjust Drosophila locomotion to nutritional state

2019

Adrenergic signaling profoundly modulates animal behavior. For example, the invertebrate counterpart of norepinephrine, octopamine, and its biological precursor and functional antagonist, tyramine, adjust motor behavior to different nutritional states. In Drosophila larvae, food deprivation increases locomotor speed via octopamine-mediated structural plasticity of neuromuscular synapses, whereas tyramine reduces locomotor speed, but the underlying cellular and molecular mechanisms remain unknown. We show that tyramine is released into the CNS to reduce motoneuron intrinsic excitability and responses to excitatory cholinergic input, both by tyraminehonoka receptor activation and by downstrea…