The natural radioactivity levels and some radiological parameters of Turkish Portland cements (PC) originated in various regions were determined in this study. The activity concentration of cement samples for 226Ra, 232Th, and 40K were measured using a gamma-ray spectrometer with high purity germanium radiation detector. The PC samples had activity concentrations of 33.0, 16.7, and 239.5 Bq kg−1 for 226Ra, 232Th, and 40K, respectively. The mean value of radium equivalent value (Raeq) was found to be 75.4 Bq kg−1. The radium equivalent values in the cement samples were lower than the acceptable level of 370 Bq kg−1. The calculated radiological parameters were found to be below the acceptance levels.
A new analytical method for the simultaneous determination of two natural hormones (progesterone and estrone) and two selected endocrine disrupter compounds (EDCs) (diltiazem and carbamazepine (Cbz)) was developed by liquid chromatography electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) after pre-concentration with solid phase extraction (SPE). Influent and effluent samples taken from five different wastewater treatment plants throughout Turkey namely Hurma/Antalya, Lara/Antalya, Kemer-1 and Kemer-2 and METU/Ankara were analyzed for their EDCs contents under the optimum conditions. All of the parameters in the pre-concentration step were optimized and the best recoveries for all compounds of interest were achieved at pH 7 (about 100%). Progesterone was not detected in any of the treatment plants while diltiazem was found in all samples with the exception of Lara effluent. 相似文献
In this paper, we apply newly developed methods called GAM & CQP and CMARS for country defaults. These are techniques refined by us using Conic Quadratic Programming. Moreover, we compare these new methods with common and regularly used classification tools, applied on 33 emerging markets’ data in the period of 1980-2005. We conclude that GAM & CQP and CMARS provide an efficient alternative in predictions. The aim of this study is to develop a model for predicting the countries’ default possibilities with the help of modern techniques of continuous optimization, especially conic quadratic programming. We want to show that the continuous optimization techniques used in data mining are also very successful in financial theory and application. By this paper we contribute to further benefits from model-based methods of applied mathematics in the financial sector. Herewith, we aim to help build up our nations. 相似文献
The structural, elastic and thermodynamic properties of thorium tetraboride (ThB4) have been investigated by using first-principles plane-wave pseudopotential density functional theory with generalized gradient approximation. The behaviors of structural parameters under 0-70 GPa hydrostatic pressure are studied by means of Broyden, Fletcher, Goldfarb, and Shanno (BFGS) geometry optimization scheme. By using the stress-strain method, single crystal elastic constants are calculated to test the mechanical stability of the crystal structure and to determine mechanical properties such as bulk modulus at each pressure. However, in order to study the thermodynamic properties of ThB4, the quasi-harmonic Debye model is used. Then, the dependencies of bulk modulus, heat capacities, thermal expansions, Grüneisen parameters and Debye temperatures on the temperature and pressure are obtained in the whole pressure range 0-70 GPa and temperature range 0-1500 K. 相似文献
The equations of motion for a self-interacting self-dual tensor in six dimensions are extracted from the equations describing the M-theory five-brane. These equations are presented in a self-contained, six-dimensional Lorentz-covariant form. In particular, it is shown that the field-sttrength tensor satisfies a non-linear generalised self-duality constraint. The self-duality equation is rewritten in five-dimensional notation and shown to be identical to the corresponding equation in the non-covariant formalism. 相似文献