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Showing 1 to 20 of 90 for “"counterion"”.
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Counterion Behavior in Biopolymers
Counterion behavior controls interactions between charged surfaces in aqueous environments, and can cause attraction between like charged objects. Mean field approaches to describing counterion behavior, such as the Poisson-Boltzmann formalism and Manning condensation theory, predict that charged …
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The Role of Potassium as a Counterion During Calcium Release From the Sarcoplasmic Reticulum
… regulation. Hence the role of K$\sp{+}$ as a counterion during Ca$\sp{2+}$ release from the SR was investigated and found to be physiologically important.
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Counterion Distribution around a Macroion in Polyelectrolytes Probed by Anomalous Small-Angle X-ray Scattering
… X-ray Scattering (ASAXS) in order to probe the counterion correlation around the macroion. In the course of this study, different polyelectrolyte systems such as, rod-like polyelectrolytes, spherical polyelectrolyte brushes and star shaped polyelectrolytes have been studied using ASAXS. ASAXS is …
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Counterion identity effects on the self-assembly processes in a series of perfluorinated surfactant - water mixtures
The effects of counterion on the lyotropic liquid crystalline phase behaviour of some quaternary ammonium salts of perfluorodecanoic acid in water have been studied using a combination of optical polarising microscopy (OPM), deuterium nuclear magnetic resonance (211 NMR) and cryo-transmission …
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Development of the cross-coupling of alcohols with olefins via positional tuning of the counterion in transition metal catalysis
Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2026-05-01
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Molecular self assembly in flurocarbon surfactant / water systems
… the tight association of the large, hydrophobic counterions with the poiar head group region. In this study a series of perfluorocarbon surfactants have been synthesised in which the hycirophobicity of the counterion is varied. The counterion is W (CH2CH2CH2CH3)(CH3) 41 whilst the surfactant ion …
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Synthesis and characterization of aminated perfluoro polymer electrolytes
… were used to exchange the polymer to alternate counterion forms. Chemical structure analysis was performed using both FT and ATR infrared spectroscopy to confirm sulfonyl fluoride replacement and the absence of sulfonic acid sites. Mechanical testing of the polymer, following counterion exchange …
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Fundamentals and application of the collapse transition of poly(acrylic acid) for synthesis of various polymer-templated nanoparticles
… can be collapsed by positively charged counterions, forming a nano-sized polymer-counterion particle. Upon stabilization of the nanoparticle via UV crosslinking, further chemical reaction of the counterions can be performed. In principle, the method can be carried out with different …
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In Situ Infrared Spectroscopic Studies of Electrodeposition Additive Adsorption on Copper
CTA with bisulfate counterion promoted smooth electrodeposits. Secondary ion mass spectroscopy (SIMS) depth profiles indicated that CTA was not significantly incorporated into copper deposits grown in the presence of CTA with HSO$\sb4\sp-$ counterion, except at very high overpotentials ($>$500 mV). …
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Molecular-thermodynamic theories of micellization of multicomponent surfactant mixtures and of pH-sensitive surfactants
… (MT) theory was developed to account for counterion binding to mixed micelles composed of ionic-nonionic and ionic-zwitterionic binary surfactant mixtures. The theory successfully predicted the degree of counterion binding ([beta]) of monovalent and multivalent ions to mixed micelles as a …
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Effects of Thermal Treatments on Perfluorosulfonate Ionomer Membranes
… the endothermic event increases with increasing counterion size. Larger tetraalkylammonium ions, tetraethylammonium(TEA+) and tetrapropylammonium(TPA+), result in no significant peak upon annealing at 200ºC. DSC thermograms of annealed Na+-form 3M Ionomer show no peak upon annealing and DSC …
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Thermodynamics and kinetics of ion-exchange in perchlorate-selective poly(vinylbenzyltrialkylammonium chloride) matrices
… correlated to both the amine modifier and counterion present in the matrix. Mass uptake is lowest in a TBA-modified film in perchlorate form and highest in a TMA-modified film in fluoride form. Water uptake results in a maximum relative compressive biaxial stress of -33 MPa and -113 MPa for …
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Star-shaped Polyelectrolytes
… pressure inside the stars due to the presence of counterions. The osmotic pressure opposes further deprotonation, resulting in a decreased acidity. The osmotic coefficient decreases with increasing arm number, indicating higher counterion confinement within structures with higher branching. The …
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Synthesis and Self-Assembly of Novel ABC Miktoarm Star Terpolymers
… iodide) (P2VPq) segment, the counterion-mediated superstructure-formation of complex shaped aggregates was thoroughly investigated. The key compound of the combinatorial synthesis is the newly synthesized 4-alkyne-substitued diphenylethylene derivative …
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Improving the solubility and dissolution of poorly soluble drugs by salt formation and the consequent effect on mechanical properties
… solubility and should readily form salts. The counterions used for salt formation were: butylamine, pentylamine, hexylamine, octylamine, benzylamine, cyclohexylamine, tert-butylamine, 2-amino-2-methylpropan2-ol, 2-amino-2-methyl propan-1,3-ol and tromethamine. Solubility was partially …
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A structural database for pharmaceutical salt selection
… molecule in combination with different counterions for the formation of a crystalline salt. This approach is necessitated by the limited understanding of the relationships between molecular and supramolecular structure and properties and the stoichiometry and ionisation state of the …
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A Computational Investigation of the Photophysical, Electronic and Bonding Properties of Exciplex-Forming Van der Waals Systems
… in the [Au(SCN)2]22- by interactions with the counterion. Weak bonding interactions and luminescent transitions were explained by calculation of Hg dimers, excimers and exciplexes formed with noble gases.
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Borenium Cations as Catalysts for the Reduction of Organic Molecules and Mechanistic Investigations into their Mode of Operation
… HBpin did not contain a nucleophilic borohydride counterion and it was isolated in the solid state. This salt was also found to reduce the same substrates with similar yields and reaction times. The mechanisms of both of these catalysts were investigated and were found to be proceeding by a …
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FLUORESCENT PROBE INVESTIGATIONS OF MICROENVIRONMENTS OF ANALYTICAL INTEREST (REVERSED-PHASE, POLYETHYLENIMINE, POLARIZATION)
… on a dynamic surface.</p><p>Polyelectrolyte-counterion binding strength and proximity were studied using a three component system: metals bound to polyethylenimine (PEI) and pyrenesulfonate counterion probes. Metals altered rates of excited state processes and defined binding environment. …
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Effect of micelles on flotation of metal ions
… dependency of the adsorption of divalent metal counterions such as copper and zinc at the air-water interface on its concentration in the solution, was undertaken in order to better understand the process of ion flotation. The study is divided into two broad categories, the first of which …
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