1,N6 -Ethenoadenine (ϵA) and cytosine (C) are able to form two different metal-mediated base pairs. When the glycosidic bonds are arranged in a cisoid manner (i.e., in antiparallel-stranded DNA), the ϵA:C mispair binds one AgI ion, leading to a mononuclear ϵA-AgI -C base pair that contains a synergistic hydrogen bond. In contrast, a transoid orientation of the glycosidic bonds (as found in para...

We report experimental and theoretical studies on ring cleavage enhancement in collisions of potassium atoms with uracil/thymine to further increase the understanding of the complex mechanisms yielding such fragmentation pathways. In these electron transfer processes time-of-flight (TOF) negative ion mass spectra were obtained in the collision energy range 13.5-23.0 eV. We note that CNO(-) is t...

Reverse Osmosis (RO) is one of the main membrane technologies currently used for desalination seawater and brackish water to produce freshwater. However, mechanism transport separation ions in RO membranes not yet fully understood. Besides acid–base reactions (i.e., including H+-ion), at high concentrations, salt can associate form ion pairs. In this study, we investigate how include formation ...

Experimental and theoretical cross sections for the resonant ion-pair formation ~RIP! in electron collisions with rovibrationally cold H3 1 ions are presented. Absolute cross sections for the RIP process producing H ions are measured for center-of-mass energies between 2–20 eV using the CRYRING, heavy-ion storage ring. Theoretical cross sections are obtained using wave-packet propagation on bot...

Two simple, rapid and inexpensive methods based on spectrophotometry and turbidimetry have been developed for the determination of cyproheptadine hydrochloride (CPH) in pure form and in dosage forms with Bromophenol Blue (BPB) as the reagent. The spectrophotometric method is based on the formation of an ion-pair complex between the drug and BPB in an acidic buffer. The ion-pair complex formed, ...

We present an analysis of the electrostatic properties in the catalytic site of papain (EC 3.4.22.2), an archetype enzyme of the C1 cysteine proteinase family, and we investigate their possible role in the formation, stabilization and regulation of the Cys25((-))...His159((+)) catalytic ion pair. The electrostatic properties were computed using a reassociation method based in multicentered mult...