Presence Of Mg Cations Research Articles

Magnesium cations assist with unpairing hydrogen-bonded 2-deoxyribose trinucleotides

2-deoxyribose trinucleotides are essential units for storage and transfer of the genetic information. Nucleotide transpositions in trinucleotide sequences affect production of different amino acids. The study focuses on the mechanism of unpairing initially H-bonded trinucleotides. In living cells, the unpairing proceeds through DNA polymerase operating only in the presence of Mg cations. The DNA polymerase is a very complex system to be studied quantum chemically. In our simplistic approach, the polymerase is replaced by two Mg cations attached to both sides of the complementary trinucleotides. A distinguished feature of Mg in cell is in its easiness to accept and donate the electron density. In a particular molecular configuration, this makes Mg singly charged. As to the current case, we observe an unpaired electron on the Mg+ and an unpaired electron on the trinucleotide − totally, a radical pair which coupling produces either triplet or singlet state. The study, based on the DFT B3LYP (6-311G** basis set) computations, shows that the singlet state energetically is less preferable than the triplet state. The latter is unstable and makes the trinucleotide strands unpair in the region where the singlet and triplet states cross.

ChemInform Abstract: Synthesis and Electrochemical Characterization of Divalent Cation-Incorporated Lithium Nickel Oxide.

Divalent cation incorporated Li{sub 1+x}NiMg{sub x}O{sub 2(1+x)} materials, corresponding to LiNi{sub 1{minus}y}Mg{sub y}O{sub 2} [y = x(1 + x)], represent a class of novel materials with unique electrochemical characteristics. Excellent cyclability (reversibility) when cycled up to high potentials (e.g., 4.4 V with respect to Li), as well as higher thermal stability in comparison to pure LiNiO{sub 2}, are the major benefits of these divalent cation incorporated materials. In the present work, a series of material compositions (x = 0, 0.05, 0.10, 0.15, and 0.20) have been successfully synthesized and electrochemically characterized. The introduction of Mg results in the elimination of phase transformations and causes smaller unit cell volume changes during cycling. More importantly, it results in a significant decrease in the capacity fade rate. Results of these studies reveal that the suppression of decomposition reactions during cycling is the prime reason for this improvement in capacity fade rate rather than the elimination of phase transformations and the smaller unit cell volume change. Suppression of the decomposition reactions is thought to be due to the prevention of overcharging of the material as well as the stabilization of NiO{sub 2} slabs caused by the presence of Mg cations.

Synthesis and Electrochemical Characterization of Divalent Cation‐Incorporated Lithium Nickel Oxide

Divalent cation incorporated materials, corresponding to , represent a class of novel materials with unique electrochemical characteristics. Excellent cyclability (reversibility) when cycled up to high potentials (e.g., 4.4 V with respect to Li), as well as higher thermal stability in comparison to pure , are the major benefits of these divalent cation incorporated materials. In the present work, a series of material compositions (x = 0, 0.05, 0.10, 0.15, and 0.20) have been successfully synthesized and electrochemically characterized. The introduction of Mg results in the elimination of phase transformations and causes smaller unit cell volume changes during cycling. More importantly, it results in a significant decrease in the capacity fade rate. Results of these studies reveal that the suppression of decomposition reactions during cycling is the prime reason for this improvement in capacity fade rate rather than the elimination of phase transformations and the smaller unit cell volume change. Suppression of the decomposition reactions is thought to be due to the prevention of overcharging of the material as well as the stabilization of slabs caused by the presence of Mg cations. © 2000 The Electrochemical Society. All rights reserved.