We developed an optrode sensing device that utilizes a polymerized colloidal array (PCCA) photonic crystal material. This array diffracts light in the visible spectral region due to the periodic spacing of colloidal particles. The PCCA changes diffraction wavelength due to binding of Pb2+ to an 18-crown-6 ether molecular recognition agent. This optrode consists of a probe assembly that contains...

The Poisson-Boltzmann equation is modified to consider charge ionogenicity, steric exclusion, and charge distribution in order to describe the perimembranous electrostatic potential profile in a manner consistent with the known morphology and biochemical composition of the cell's glycocalyx. Exact numerical and approximate analytical solutions are given for various charge distributions and for ...

An AutoAnalyzer method for serum iron was found to be giving erroneously high values owing to a Donnan equilibrium effect on the rate of dialysis of ferrous ions. The addition of neutral salt to the reagent corrected the deficiency. The validity of other assays on the AutoAnalyzer that measure dialyzable ions in the presence of relatively high concentrations of protein should be verified in vie...

Excised roots of barley (Hordeum vulgare, var. Campana) were incubated for periods up to 24 hours in salt solutions of various concentrations and ion accumulation was determined at various time intervals. The data were consistent with the existence of 2 components of ion uptake, one accounting for ion uptake from solutions below 1 mm and both components contributing to uptake from solutions of ...

The curvature stress of DNA packed inside a phage is balanced against its electrostatic self-interaction. The DNA density is supposed nonuniform and as a result the Donnan effect is also inhomogeneous. The coarse-grained DNA density is a nonlinear function of the DNA radius of curvature at a given position inside the bacteriophage. It turns out that a region (or regions) exists totally free fro...