The effect of ionic and non-ionic excipients and additives as modulators of swelling and erosion kinetics and verapamil HCl release from guar-based matrix tablets was investigated. Tablet dissolution, erosion and water uptake studies were carried out using a modified USP 23 Apparatus 2 method. The kinetics of gel strength and texture development were studied by textural analysis. Near linear dr...

the binding of sodium n-dodecyl sulphate (sds) to aspergillus niger catalase in various ionic strengths at ph 6.4 and a temperature of 27? and 37?c has been studied over a range of sds concentrations using equilibrium dialysis and fluorescence spectroscopy techniques. the binding data were used and interpreted in terms of theoretical models (scatchard equation and wyman binding potential). the ...

– We present molecular dynamics simulations on strongly charged polyelectrolytes in poor solvent. The resulting pearl-necklace conformations are analyzed in detail. Fluctuations in the number of pearls and their sizes lead only to small signatures in the form factor and the force-extension relation, which is a severe obstacle for experimental observations. We find that the position of the first...

The synthesis and antibacterial activity of a series of N-acyl 3-isopropylidenyl- and 3-isopropyl 2-azetidinones having potent in vitro antibacterial activity, particularly against anaerobic organisms, is described. A distinguishing structural feature of these compounds is the lack of any ionizable moiety appendant to the lactam nitrogen.

The acid-base dissociation constant (pK(a)) of a drug is a key physicochemical parameter influencing many biopharmaceutical characteristics. While this has been well established, the overall proportion of non-ionizable and ionizable compounds for drug-like substances is not well known. Even less well known is the overall distribution of acid and base pK(a) values. The current study has reviewed...

Utilizing the charge-transfer-to-solvent transition of Na , we measure the excited-state lifetime of the solvated electron (e s ) in tetrahydrofuran (THF) in each of three different well-defined local solvent environments: an isolated THF cavity, a THF cavity with a sodium atom located one solvent shell away, and a THF cavity with a sodium atom in the first solvent shell. We find that the excit...

In this communication, we report that ionizable, tertiary amine-based block copolymers can be used as pH-responsive contrast agents for magnetic resonance imaging (MRI) through the chemical exchange saturation transfer (CEST) mechanism. The CEST signal is essentially "off" when the polymers form micelles near physiological pH but is activated to the "on" state when the micelles dissociate in an...