Yüksel Özdemir

Evaluation of Root Canal Dentin after Nd:YAG Laser Irradiation and Treatment with Five Different Irrigation Solutions: A Preliminary Study

This study evaluated in vitro any changes in the morphology and mineral content of root canal dentin after treatments with Nd:YAG laser irradiation and 5 different irrigation solutions. The groups of extracted single-rooted human teeth were exposed to sterile saline solution, 5.25% NaOCl, 3% H2O2, 15% ethylenediaminetetraacetic acid, 2% chlorhexidine gluconate, and Nd:YAG laser irradiation. All prepared teeth were bisected longitudinally; half of each tooth was used for wavelength dispersive x-ray fluorescence spectrometry analysis to assess the mineral content. The other half was studied by using scanning electron microscopy to analyze the surface of the dentin. The results showed that the calcium level and calcium/phosphorus ratio decreased significantly with the NaOCl irrigation solutions (p < .05), suggesting the presence of changes at molecular level. Significant differences among the test groups were also observed in the scanning electron microscopy evaluation (p < .05). The lowest scores for root cleaning were obtained by using ethylenediaminetetraacetic acid followed by Nd:YAG laser treatment.

Gamma-ray energy absorption and exposure buildup factor studies in some human tissues with endometriosis

Human tissues with endometriosis have been analyzed in terms of energy absorption (EABF) and exposure (EBF) buildup factors using the five-parameter geometric progression (G-P) fitting formula in the energy region 0.015-15 MeV up to a penetration depth of 40 mfp (mean free path). Chemical compositions of the tissue samples were determined using a wavelength dispersive X-ray fluorescence spectrometer (WDXRFS). Possible conclusions were drawn due to significant variations in EABF and EBF for the selected tissues when photon energy, penetration depth and chemical composition changed. Buildup factors so obtained may be of use when the method of choice for treatment of endometriosis is radiotherapy.

Energy absorption and exposure buildup factors for some polymers and tissue substitute materials: photon energy, penetration depth and chemical composition dependence

The gamma ray energy absorption and exposure buildup factors have been calculated by using the five parameter geometric progression (GP) fitting formula for some polymers and tissue substitute materials in the energy region 0.015-15 MeV up to a penetration depth of 40 mean free paths. From the results, it is worth noting that significant variations occur in gamma ray buildup factors for the given polymers and tissue substitute materials depending on photon energy, penetration depth and chemical composition of the materials. Also, it was observed that there are significant variations between energy absorption (EABF) and exposure (EBF) buildup factors which may be due to the variations in chemical composition of the materials used. Finally, it is expected that the presented buildup factor data may be helpful in (a) estimating the effective dose to be given to patients in radiation therapy and diagnostics, hence allowing corrections to be made to the intensity of radiation, as it is somewhat problematic to evaluate the real absorbed dose in critical organs due to the probability of photon buildup somewhere inside the medium; (b) estimating the health hazards arising from the exposure of the human body to radiation, thus it will be helpful in controlling the exposure of the human body to radiation.

Measurement of atomic L shell Coster-Kronig yields (f12, f23 and f13) for some elements in the atomic number range 59⩽Z⩽90

Non-radiative transitions cause changes in the generation of the intensity of the L lines. In order to investigate the physical quantities relevant to the L lines affected by the non-radiative transitions, experimental measurements were carried out using a Si(Li) x-ray spectrometer. Atomic L shell Coster-Kronig yields (f12, f13 and f23) for some elements in the atomic number range 59≤Z≤90 were determined. These selected measured semi-empirical values were also fitted by least squares to polynomials in Z of the form ∑nanZn (except for f13) and compared with theoretical and with earlier fitted values.

Measurement of atomic L shell fluorescence (ω1, ω2, ω3) and Auger (a1, a2 and a3) yields for some elements in the atomic number range 59≤Z≤85

Abstract A comprehensive set of theoretical Coster–Kronig and fluorescence yields are presented for atomic numbers 18≤Z≤100. These quantities are based on ab initio relativistic calculations. Agreement with experimental values is fair for ω1 and generally good for ω2, ω3 (Z≥54) [1] . Therefore, atomic L shell fluorescence (ω1, ω2, ω3) and Auger yields (a1, a2 and a3) for some elements in the atomic number range 59≤Z≤85 were determined. These selected measured semi-empirical values were also fitted by least squares to polynomials in the Z of the form ∑nanZn and compared with theoretical and with earlier fitted values.

Photon-induced M-shell X-ray production cross-sections and fluorescence yields in heavy elements at 5.96 keV

Abstract Total M-shell X-ray production cross-sections (MXRP) for selected heavy elements between Yb and U at have been measured at 5.96 keV incident photon energy using a Si(Li) detector. The average M-shell fluorescence yields have been derived, using the experimental total M X-ray production cross-sections and theoretical M-shell photoionization cross-sections. Extracted cross-sections and fluorescence yields have been compared with the literature experimental values, theoretical predictions and semiempirical fits.

L, Lα, Lβ and Lγ X-ray production cross-sections and yields of some selected elements between caesium and erbium following ionization by 59.54 keV γ rays

Abstract L l , Lα, Lβ and Lγ X-ray production cross-sections were measured in elements from Cs to Er following ionization for 59.54 keV γ-rays from an 241Am point source. The measured values are compared with theoretical predictions estimated using subshell photoionization cross-sections, fluorescence yields, Coster–Kronig transition probabilities, K to Li subshell vacancy transfer probabilities and radiative decay rates. Average L-shell fluorescence yields were deduced from present measured total L X-ray production cross-sections, theoretical K and L photoionization cross-sections and K to L vacancy transfer probabilities. The obtained results for L X-ray production cross-sections and average L-shell fluorescence yields are compared with recent experimental values, theoretical predictions, and semiempirical fits.

L-shell polarization and alignment of heavy elements induced by 59.54 keV photons

The polarization (%) of L-shell fluorescent X-rays (Lα, Lβ and Ll) of Lu, Hf, Ta, W, Os, Pt, Au, Hg, Tl, Pb, Bi, Th and U excited by 59.54keV photons has been measured. These polarization degrees were then used to determine the alignment parameters A(2.) The Ll X-rays were found to be strongly polarized, whereas Lα and Lβ X-rays showed less polarization. In this regard, the Lα, Lβ and Ll groups show anisotropic spatial distributions. The results for polarization (%) as well as alignment parameters were compared with the ones available in literature.

L-subshell fluorescence yields (ω1, ω2 and ω3) for elements in the atomic range 55 ≤ Z ≤ 68 with a Si(Li) detector

Abstract Lα, Lβ and Lγ X-ray production cross-sections of 55 Cs , 56 Ba , 57 La , 58 Ce , 59 Pr , 60 Nd , 62 Sm , 65 Tb , 66 Dy , 67 Ho and 68 Er have been measured by using a Si(Li) detector coupled to a model 1024 computerized multi-channel analyzer. The L-subshell X-ray fluorescence yields ω1, ω2 and ω3 have been derived, using the experimental Lα, Lβ and Lγ X-ray production cross-sections, theoretical L-subshell photoionization cross-sections, Coster-Kronig transition probabilities, vacancy transfer probabilities and fractional X-ray emission rates. The experimental data have been compared with the literature experimental data, theoretical predictions based on Dirac–Hartree–Slater wave functions and semiempirical compilations.

K- to L- and M-shell radiative vacancy transfer probability measurements in some elements from Nd to Pb

Radiative vacancy transfer probabilities from K-shell to -subshell and M-shell were deduced for the elements Nd, Sm, Eu, Gd, Dy, Ho, Er, Yb, Ta, W, Hg and Pb by measuring characteristic K x-rays from targets excited by 123.6 keV photons. Comparisons between present experimental results and theoretical predictions were made.