ABSTRACT
We derive approximate analytical expressions for the effective permittivity tensor of two-phase metamaterials whose geometry is close to one-dimensional (quasi-one-dimensional metamaterials). Specifically, we consider the metamaterial made of parallel slabs with width given by a linear or parabolic function. Using our approach, the design of epsilon-near-zero, ultra-low and high refractive index metallodielectric metamaterials with extended bandwidth has been demonstrated. In addition, generalizations to the three-dimensional case and some limitations of the presented technique are briefly considered.
ABSTRACT
We analyzed the long-range intermolecular interaction between fragments of broken DNA. We considered two constituents of long-range intermolecular interaction. The first is a net electrostatic Coulomb interaction between charges, involved in a structure of opposite nucleotides, which we evaluate using Debye-Huckel theory. The second one is the Van der Waals interaction between the nucleotides. The general Lifshitz theory of Van der Waals forces was used to evaluate this interaction. Numerical calculations showed that a repulsive force between broken DNA fragments can arise in specific cases. This repulsion can prevent DNA from repairing itself after a double-strand break. The height of the barrier decreases with an increase of the ionic strength of the intracellular milieu, or with a reduction of its viscosity.
Subject(s)
DNA Fragmentation , DNA Repair , DNA/chemistry , Models, Chemical , Models, Molecular , Nucleotides/chemistry , Base Pairing , Binding Sites , Computer Simulation , DNA Damage , Energy Transfer , Macromolecular Substances , Nucleic Acid Conformation , Static ElectricityABSTRACT
In this work, the long-range interaction between the pairs of nucleotides situated on the opposite ends of a double broken DNA helix have been studied theoretically. The long-range energy was considered as a sum of electrodynamics Van der Waals and electrostatic Coulomb interactions. The most important region for the problem under consideration is about 5-15 A between the nucleotides. The calculations of the energy of long-range interaction have shown that during the interaction between the pairs CG-CG, there is a potential repulsive barrier with the amplitude of about 4 kT at the distance of 7-9 A, and during the interaction between the pairs TA-TA, there is a potential repulsive barrier with the amplitude of about 1.5 kT at the same distance, which can prevent DNA from enzyme selfrepairing after a double DNA break. This barrier vanishes as the pH of intracellular medium increases. The remainder pairs of nucleotides do not have such barrier, and there is always an attraction like interaction.
