The aggregation and reaction with oxygen of the tetrasodium salt of cobalt phthalocyanine-4,4',4'',4'''-tetrasulphonic acid

1973 ◽  
Vol 26 (2) ◽  
pp. 319 ◽  
Author(s):  
LC Gruen ◽  
RJ Blagrove
Keyword(s):  
Aqueous Solution ◽  
Ionic Strength ◽  
Molecular Oxygen ◽  
Absorption Spectra ◽  
Alkaline Solution ◽  
Cobalt Phthalocyanine ◽  
Visible Absorption ◽  
Reversible Addition ◽  
Dimeric Form ◽  
Low Ionic Strength

The reversible addition of molecular oxygen to the tetrasodium salt of cobalt phthalocyanine-4,4?,4?,4??-tetrasulphonic acid in aqueous solution has been confirmed. Visible absorption spectra of the monomeric and dimeric species and of the oxygen adduct have been determined. A monomer-dimer system prevails at neutral pH, low ionic strength, and low dye concentrations. The oxygen adduct and the dimeric form of the dye predominate in alkaline solution.

Viscosimetric studies of chitosan nitrate and chitosan chlorhydrate in acid free NaCl aqueous solution

e-Polymers ◽  
2008 ◽  
Vol 8 (1) ◽  
Author(s):  
Cristóbal Lárez Velásquez ◽  
Joel Sánchez Albornoz ◽  
Enrique Millán Barrios
Keyword(s):  
Aqueous Solution ◽  
Ionic Strength ◽  
Aqueous Solutions ◽  
Aqueous Medium ◽  
Intrinsic Viscosity ◽  
Free Acid ◽  
Film Formation ◽  
Stiffness Parameter ◽  
Low Ionic Strength

AbstractTwo salts of the biopolymer chitosan were prepared in aqueous medium by employing an excess of HCl or HNO3 in order to ensure neutralization of all NH2-chitosan groups. Chitosan salts were extensively dialyzed in dionised water and dried at 40 ºC until film formation. The films were characterized by thermogravimetry, FTIR and conductimetric tritration. QH+Cl− and QH+NO3− salts were viscosimetrically evaluated in free acid aqueous solutions in the presence of NaCl to control ionic strength of the medium. Unexpected high intrinsic viscosity values were obtained at low ionic strength when QH+NO3− salt were evaluated. Smidsrod´s approach was employed to estimate the stiffness parameter of both salts and B = 0.084 and 0.120 for QH+Cl− and QH+NO3−, respectively, were obtained.

scholarly journals The stability and aggregation properties of human liver acid β-d-galactosidase

1981 ◽  
Vol 193 (3) ◽  
pp. 773-779 ◽  
Author(s):  
C M Heyworth ◽  
E F Neumann ◽  
C H Wynn
Keyword(s):  
Ionic Strength ◽  
Molecular Form ◽  
Active Form ◽  
Gel Filtration ◽  
British Library ◽  
Fluorescence Excitation ◽  
Dimeric Form ◽  
The Stability ◽  
Low Ionic Strength ◽  
Beta Galactosidase

1. A method is described for following continuously the action of beta-galactosidase on 4-methylumbelliferyl beta-D-galactoside at pH 4.5, in which 4-methylumbelliferone production is measured at fluorescence excitation and emission wavelengths of 324 and 444nm respectively. 2. Initial-rate studies show that the presence of salt activates beta-galactosidase up to 100 mM, but is inhibitory above that concentration. The enzyme is very unstable at 37 degrees C and low ionic strength, but stability increases with ionic strength. 3. The stability of the enzyme at 37 degrees C decreases markedly with rising pH in the range 5.9–8.0. 4. Gel-filtration patterns demonstrate that there is a marked tendency to polymerization with increasing ionic strength. The gel-filtration pattern shows decreasing amounts of dimer with increasing pH. 5. The correlation between activity, stability and molecular form of beta-galactosidase is discussed. It is suggested that the dimeric form of the enzyme is the most stable and active form. The implications of this finding for the assay of beta-galactosidase under physiological conditions for prenatal diagnosis are discussed. 6. Evidence for the possible occurrence of a 36 000-mol.wt. from of beta-galactosidase is presented. 7. A computer program for the calculation of initial rates has been deposited as Supplementary Publication SUP 50114 (4 pages) at the British Library Lending Division, Boston Spa, Wetherby, West Yorkshire LS23 7BQ, U.K., from whom copies can be obtained on the terms indicated in Biochem. J. (1981) 193, 5.

Dihexadecyl Phosphate Vesicles: Difference in the Spectroscopic Properties of Tris(2,2′-bipyridine)ruthenium(II) Adsorbed on the Inner and Outer Surfaces

1985 ◽  
Vol 38 (4) ◽  
pp. 527 ◽  
Author(s):  
Y Tricot ◽  
DN Furlong ◽  
AWH Mau ◽  
WHF Sasse
Keyword(s):  
Aqueous Solution ◽  
Absorption Spectrum ◽  
Excited State ◽  
Ionic Strength ◽  
Outer Surface ◽  
Spectroscopic Properties ◽  
Visible Absorption Spectrum ◽  
Visible Absorption ◽  
Aqueous Environments ◽  
Quenching By Oxygen

The visible absorption spectrum of tris (2,2′-bipyridine)ruthenium(II) [ Ru ( bpy )32+] adsorbed on the outer surface of dihexadecyl phosphate vesicles is indistinguishable from the spectrum of free Ru ( bpy )32+ in aqueous solution. By contrast, the absorption spectrum of Ru ( bpy )32+ that is entrapped in vesicles by adsorption on inner surfaces exhibits a red shift in its visible absorption peak, and the extinction coefficient for this peak is increased. The emission spectrum for outer-adsorbed Ru ( bpy )32+ is red-shifted whilst that for inner-adsorbed Ru ( bpy )32+ is blue-shifted, compared with the spectrum for free Ru ( bpy )32+ in solution. The excited state of Ru ( bpy )32+ was longer lived, and was much less sensitive to quenching by oxygen, when the complex was adsorbed on inner vesicle walls. The above spectral variations indicate that the adsorption of Ru ( bpy )32+ on inner surfaces occurs in a way which leads to more spatial restriction on Ru ( bpy )32+ ions than does adsorption on outer surfaces of the bilayer . This asymmetry may be due to differences in the packing of dihexadecyl phosphate molecules as well as in the ionic strength of inner and outer aqueous environments.

Revisiting actinide–DTPA complexes in aqueous solution by CE-ICPMS and ab initio molecular dynamics

RSC Advances ◽  
2016 ◽  
Vol 6 (67) ◽  
pp. 62729-62741 ◽  
Author(s):  
L. Bonin ◽  
J. Aupiais ◽  
M. Kerbaa ◽  
P. Moisy ◽  
S. Topin ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Aqueous Solution ◽  
Ionic Strength ◽  
Ab Initio ◽  
Reliable Data ◽  
Ab Initio Molecular Dynamics ◽  
Diethylenetriaminepentaacetic Acid ◽  
Low Ionic Strength

Although thermodynamics of AnIVDTPA− (DTPA = diethylenetriaminepentaacetic acid) complexation have been reported for 50 years, reliable data at low ionic strength is still missing.

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