A model in which two positively-charged titratable sites enhance the affinity for anionic substrates can explain the increase in external iodide dissociation constant (K(O)(I)) with increasing pH(O) (Liu, S. J., F.-Y. Law, and P.A. Knauf. 1996.f Gen.Physiol. 107:271-291). If sulfate binds to the same external site as I-, this model predicts that the SO(4)= dissociation constant (K(O)(S)) should...

The acid dissociation constants of the hydroxyl groups in 25, 26, 27, 28-tetrahydroxy-5, 11, 17, 23-tetrasulphonic-calix[4]arene (SC4) were determined at 25οC by a combination of potentiometric and spectrophotometric titration method. The first and second acid dissociation constants (pKa1, pKa2) were found to be 3.19 and 12.1, which demonstrated pKa shift due to intramolecular hydrogen bonding ...

The oxidation of phenols by HFeO4(-) proceeds via a hydrogen atom transfer (HAT) mechanism, as evidenced by a large deuterium isotope effect and a linear correlation between the log(rate constant) and bond dissociation free energy (BDFE) of phenols. The Marcus cross relation has been applied to predict the rate constant of HAT from hydroquinone to HFeO4(-).

New method for dissociation of diatomic molecule based on nonperiodic excitation generated by energy-feedback control mechanism is proposed. The energyfeedback control uses frequency-energy (FE) relation of the natural oscillations to fulfill the resonance conditions at any time of excitation. Efficiency of the proposed method is demonstrated by the problem of dissociation of hydrogen fluoride ...

β-Lactamase inhibitory protein II (BLIP-II) is a potent inhibitor of class A β-lactamases. KPC-2 is a class A β-lactamase that is capable of hydrolyzing carbapenems and has become a widespread source of resistance to these drugs for Gram-negative bacteria. Determination of association and dissociation rate constants for binding between BLIP-II and KPC-2 reveals a very tight interaction with a c...

The acid dissociation constant is an important physicochemical parameter of a substance, and knowledge of it is of fundamental importance in a wide range of applications and research areas. We present a critical review of published methods and approaches for the determination of acid dissociation constants, with a special emphasis on the pKa values of active pharmaceutical ingredients. a 2007 E...

It is now generally agreed that the oxygen saturation of the arterial blood in normal man in rest at low altitudes is remarkably constant. Until recently, subnormal arterial saturations could almost invariably be traced to obvious pulmonary or cardiac disorders. Recently, however, it was noted that relative arterial unsaturation is common among patients with cirrhosis of the liver and other con...

The dependence of the actual/effective ionic concentration on nominal salt is experimentally investigated for aqueous solutions NaCl and KCl. actual bulk density determined by means impedance spectroscopy technique using two approaches data analysis: A first approach scrutinizing real part's plateau cell's electric spectrum versus dopant when written in series representation. second one via ext...