No abstract

The diluted mixed-spin Ising system consisting of spin 1/2 and spin 1 with a transverse random field is studied by the use of an effective-field method within the framework of a single-site cluster theory. The equations are derived using a probability distribution method based on the use of Van der Waerden identities. The phase diagrams are investigated for various lattice structures both for pure and diluted systems, where the transverse field is bimodally and trimodally distributed.

Passage of ionizing radiation into the biological medium plays an important role in a variety of chemical modifications, directly or indirectly of the four DNA bases. However, up to now proton collisions on DNA bases remain experimentally approached and a theoretical model for total cross section, stopping cross section and Bragg peak calculation are poorly characterized. In this current work, we restricted our study on the interaction of energetic ion proton beams with DNA base adenine (C5H5N5). The total cross section produced by high energy impact of protons are here analytically investigated via a novel model combining two methods-the Rudd semi-empirical formulas to calculate the ionization and the analytic method based on the similitude between the electron energy loss in adenine and liquid water to calculate the excitation and charge-transfer-these cross sections used to describe the total stopping cross section of adenine molecule by protons including the nuclear stopping powers. We give in this work an estimation of the Bragg peak profile and position with impact energies ranging from 1 to 20 MeV/amu. The results are compared to the available experimental, theoretical and Monte-Carlo results, and reasonable agreements are generally observed especially for the ionization. The proposed method is useful as an alternative to traditional approaches, and is useful for studies of various radiation effects in other biological material.

No abstract

The diluted mixed spin Ising system consisting of spin-1/2 and spin-1 with a random field is studied by the use of the finite cluster approximation within the framework of a single-site cluster theory. The state equations are derived using a probability distribution method based on the use of Van der Waerden identities. In this approach, the complete phase diagrams are investigated for the simple cubic lattice, when the random field is bimodally and trimodally distributed. The internal energy, specific heat and susceptibility are also calculated for both kinds of probability distributions.