Effect of ionic ordering in conductivity experiments of DNA aqueous solutions

The effects of ionic ordering in DNA water solutions are studied by conductivity experiments. The conductivity measurements are performed for the solutions of DNA with KCl salt in the temperature range from 28 to 70 C. Salt concentration vary from 0 to 2 M. The conductivity of solutions without DNA but with the same concentration of KCl salt are also performed. The results show that in case of salt free solution of DNA the melting process of the double helix is observed, while in case of DNA solution with added salt the macromolecule denaturation is not featured. For salt concentrations lower than some critical one (0.4 M) the conductivity of DNA solution is higher than the conductivity of KCl water solution without DNA. Starting from the critical concentration the conductivity of KCl solution is higher than the conductivity of DNA solution with added salt. For description of the experimental data phenomenological model is elaborated basing on electrolyte theory. In framework of the developed model a mechanism of counterion ordering is introduced. According to this mechanism under the low salt concentrations electrical conductivity of the system is caused by counterions of DNA ion-hydrate shell. Increasing the amount of salt to the critical concentration counterions condense on DNA polyanion. Further increase of salt concentration leads to the formation of DNA-salt complexes that decreases the conductivity of the system.Comment: 12 pages, 6figures. Ukr. J. Phys. (2014

Thermodynamics Characterization of Density models for an Effective Solar Water Heater Sizing

The problem faced in Sizing of an effective Solar Water Heater (SWH) by engineers to meet certain design requirement is highly enormous. Using the thermodynamic characterization relation and the knowledge of Solar Water Heater (SWH) density’s model; various design were evaluated. The result shows that density model actually predicts adequately and providing alternative means of estimating these design parameters. Also, the properties of the system, such as entropy and enthalpy (specific heat capacities), which cannot be determined directly from experimental axiom, were evaluated. These evaluations therefore, give room to express the thermodynamics properties of the system and consequently improve the design performance. Further comparisons with experimental results reveal a better outfit. Therefore through the knowledge of thermodynamic relation an efficient Solar Water Heater is operated and empirical data is expanded