Hasan Gümüş

Neuroprotective effects of melatonin and omega-3 on hippocampal cells prenatally exposed to 900 MHz electromagnetic fields.

Abstract Purpose: Adverse effects on human health caused by electromagnetic fields (EMF) associated with the use of mobile phones, particularly among young people, are increasing all the time. The potential deleterious effects of EMF exposure resulting from mobile phones being used in close proximity to the brain require particular evaluation. However, only a limited number of studies have investigated the effects of prenatal exposure to EMF in the development of the pyramidal cells using melatonin (MEL) and omega-3 (ω-3). Materials and methods: We established seven groups of pregnant rats consisting of three animals each; control (CONT), SHAM, EMF, EMF + MEL, MEL, EMF + ω-3 and ω-3 alone. The rats in the EMF, EMF + MEL, EMF + ω-3 groups were exposed to 900 MHz EMF for 60 min/day in an exposure tube during the gestation period. The CONT, MEL and ω-3 group rats were not placed inside the exposure tube or exposed to EMF during the study period. After delivery, only spontaneously delivered male rat pups were selected for the establishment of further groups. Each group of offspring consisted of six animals. The optical fractionator technique was used to determine total pyramidal neuron numbers in the rat hippocampal region. Results: The total number of pyramidal cells in the cornu ammonis (CA) in the EMF group was significantly lower than in the CONT, SHAM, EMF + MEL, and EMF + ω-3 groups. No significant difference was observed between the EMF, MEL and ω-3 groups. No difference was also observed between any groups in terms of rats’ body or brain weights. Conclusion: MEL and ω-3 can protect the cell against neuronal damage in the hippocampus induced by 900 MHz EMF. However, further studies are now needed to evaluate the chronic effects of 900 MHz EMF on the brain in the prenatal period.

New stopping power formula for intermediate energy electrons.

This study presents a new stopping power (SP) formula for electrons. In the modified Bethe-Bloch SP expression, analytical expressions for the effective charge and effective mean excitation energies (EMEE) of target atoms are used, while for the effective charge of incoming electrons, Sugiyamas semiempirical formula from Peterson and Green is used. An analytical expression for practical SP calculations is obtained using the Bethe approximation and a Thomas-Fermi model of the atom. The calculated results of the SP for electrons in some materials, such as H(2)O, H(2), CO(2), N(2), and O(2), are compared with experimental data, together with Penelope code results and a number of other semiempirical and analytical calculations.

Calculation of average projected range and range straggling of charged particles in solids

Abstract Based on the KRAL equations (Ashworth et al., 1991. J. Phys. D 24, 1376–1380), which take into account second-order energy loss moments, projected ranges and range moments of ions in mono-atomic targets were calculated. For this purpose, the set of three coupled differential equations of second order was first reduced to a set of differential equations of first order, and solved afterwards numerically, using initial values with respect to the electronic stopping power according to Montenegro et al. (1981) which are valid at non-relativistic velocities in all solid targets and are consistent with experimental data for a wide range of energies. The numerical solution of the KRAL equations was performed by applying a continuous Runge–Kutta method of seventh–eighth order and a Fehlberg Runge–Kutta method of fourth–fifth order. The results with respect to the projected ranges of Xe ions in amorphous Si are in a good agreement with measured data, and those with respect to the projected ranges and range straggling of H or B ions in amorphous Si with data calculated by the standard theories TRIM, PRAL 97 and WS (Wang and Shi, 1990. J. Phys. D 23, 1282–1289).

Effective stopping charges and stopping power calculations for heavy ions

In this study the model suggested by Sugiyama has been developed and applied for the calculation of the stopping powers for nonrelativistic heavy ions in various target materials. Sugiyamas model has been expanded to low and high energy regions in our work. Analytical expressions are obtained in the modified BB stopping power formula for the effective charge and effective mean excitation energies. In the modified LSS formula, a quasi-molecule criterion has been applied to both the projectiles and the target atoms. Electronic excitation contribution, S e0, and quasi-molecule contribution, S ei , to stopping power were found for a wide energy region. It is observed that in intermediate energy region both contributions have maxima. The stopping power due to excitation-ionization in the intermediate and higher energy region is found to be dominant, whereas quasi-molecule contribution is dominant in the lower energy region. The calculated results of stopping power are in good agreement with experimental data for various ions and targets within a few percent in a wide projectile energy range.

The natural and artificial radionuclides in drinking water samples and consequent population doses

Abstract Concentration levels of 226Ra, 228Ra, 40K and 137Cs were determined in 52 drinking water samples collected from the different supplies in Samsun province to evaluate annual effective dose due to the ingestion of the drinking water samples. The activity concentrations of 226Ra, 228Ra and 40K natural radionuclides in the drinking water samples varied from <27 to 2431mBqL−1, <36 to 270mBqL−1 and <47 to 2880mBqL−1 respectively. The activity concentrations of the artificial radionuclide 137Cs in the drinking water samples were lower than minimum detectable activity except in one drinking water sample (DW14) with an associated activity concentration of 2576mBqL−1. Contributions of the consumed water samples to annual effective dose from 226Ra, 228Ra and 40K varied from 1.6 to 33.4μSvy−1 with a mean of 6.1μSvy−1, 2.2 to 46.8μSvy−1 with a mean of 8.6μSvy−1, 4.7 to 97.5μSvy−1 with a mean of 17.9μSvy−1 for infants, children and adults, respectively. The results showed that all values of the annual effective dose of ingestion of these water samples were below the individual dose criterion of 100μSvy−1 reported by World Health Organization (WHO).

Measurement of the terrestrial and anthropogenic radionuclide concentrations in Bafra Kizilirmak delta (bird sanctuary) in Turkey

In this study, the activity concentrations of terrestrial and anthropogenic radionuclides in the soil samples collected from Bafra Kızılırmak Delta were measured by using gamma spectrometry with an NaI(Tl) detector. The average values of activity concentrations of (238)U, (232)Th and (40)K were found to be 37.2±2.8, 33.7±3.1 and 413.0±59.8 Bq kg(-1), respectively. (137)Cs was also measured in some samples. It has a mean value of 13.8±1.0 Bq kg(-1). From the activity concentrations, the absorbed gamma dose rates in outdoor and the corresponding annual effective dose rates and external hazard index (Hex) were estimated.

Natural activity concentrations in bottled drinking water and consequent doses

The radioactivity concentrations of nuclides (238)U, (232)Th and (40)K in bottled drinking water from six different manufacturers from Turkey were measured using high-resolution gamma-ray spectrometry. The measurement was done using a coaxial high-purity germanium detector system coupled to Ortec-Dspect jr digital MCA system. The average measured activity concentrations of the nuclides (238)U, (232)Th and (40)K are found to be 0.781, 1.05 and 2.19 Bq l(-1), respectively. The measured activity concentrations have been compared with similar studies from different locations. The annual effective doses for ingestion of radionuclides in the water are found to be 0.0246 mSv for (238)U and 0.169 mSv for (232)Th.

Total Electron Stopping Powers and CSDA-Ranges from 20 eV to 10 MeV Electron Energies for Components of DNA and RNA

Abstract An appropriate formula for the total stopping power of electrons of initial kinetic energy from 20 eV to 10 MeV in some biological materials is presented. The continuous slowing down approximation-range (CSDA-range) from the total stopping power is also made. The collisional stopping power formula is evaluated using Generalized Oscillator Strength (GOS) model and exchange correction on the inelastic differential cross section (IDCS) given by [M. Inokuti, Rev. Mod. Phys. 43 (1971) 297–347] and the radiative stopping power formula is calculated from the bremsstrahlung differential cross section (DCS) given by [H.W. Koch, J.W. Motz, Rev. Mod. Phys. 31 (4) (1959) 920–955]. Calculation of the total stopping powers (SPs) and CSDA-range for biological compounds: C 5 H 5 N 5 (adenine), C 5 H 5 N 5 O (guanine), C 4 H 5 N 3 O (cytosine), C 5 H 6 N 2 O 2 (thymine), C 4 H 4 N 2 O 2 (uracil), C 4 H 8 O (tetrahydrofuran), C 4 H 8 O 2 (3-hydroxytetrahydrofuran), C 5 H 10 O 2 ( α -tetrahydrofurfuryl alcohol), H 3 PO 4 (phosphoric acid), C 19 H 26 N 8 O 13 P 2 (thymine adenine DNA) have been introduced for incident electrons in the 20 eV–10 MeV energy range. The calculated results have been compared with experimental data, PENELOPE program results and other theoretical results. The calculated results of total stopping power and CSDA-ranges for electrons in energy range from 20 eV to 10 MeV are found to be in good agreement to within 8% with available data.

SVZ Sum Rules in Quantum Mechanics

In this work we obtained ground state energy level of well known harmonic oscillator in quantum mechanics by using SVZ sum rules. We calculated energy eigenvalues with and without an external electric field.