The evaluation of the 1001.03 keV gamma emission absolute intensity using fundamental parameter method.

The accurate evaluation of the absolute intensity of the gamma-ray transition 1001.03 keV of 234mPa is crucial for accurate determination of 238U in nuclear material and environmental samples. Over the last decades, a wide range of 1001.03 keV absolute intensity values were published by different researchers and ranged from 0.59 to 1.12%. Nowadays, one of the most commonly used values is 0.847 ± 0.008% that seems not accurate and would eventually lead to an overestimation of 238U activity concentration. The absolute intensity of 1001.03 keV gamma transition was re-evaluated using different fundamental parameter method (FPM) modes, uranium ore and granite samples, samples' geometries, sample-to-detectors' geometries and gamma ray spectrometers. The mean ± standard deviation of newly optimized absolute intensity value is 1.067 ± 0.084% with an average relative bias of - 20% from the commonly used value.

The re-evaluation of the 234mPa's 1001.03 keV gamma emission absolute intensity for the precise assessment of 238U.

In this study the commonly used f-value for the 1001.03 keV (0.835 ± 0.004%) energy transition of the 234mPa was re-evaluated due to an obvious consistent overestimation of the 238U activity concentration. Different calibration protocols, samples' matrices and geometries, and gamma-ray spectrometers were exploited in order to assure the accuracy of the derived data. An average positive relative bias of about 24% from the currently used f-value was estimating leading to newly adopted f-value of 1.037 ± 0.052%. This newly suggested f-value will lead to an improvement in the accurate assessment process of the 238U using gamma-ray spectrometry in both environmental and nuclear safeguard fields.

A simplified gamma-ray self-attenuation correction in bulk samples.

Gamma-ray spectrometry is a very powerful tool for radioactivity measurements. For accurate gamma-ray spectrometry, certain correction measures should be considered, for instance, systematic uncertainty in the photo-peak efficiency due to the differences between the matrix (density and chemical composition) of the reference and the other bulk samples. Therefore, gamma-ray attenuation correction factors are of major concern for precise gamma-ray spectrometry. Simple practical correction for the photo-peak efficiency, due to discrepancies in both the samples' matrices and densities (self-attenuation), is performed in this study. This study suggests a brief measurement of relative photons transmission through both reference and unknown bulk samples where the variations of photon transmissions are assumed to be linearly correlated to the samples' densities. Specific correction factors would be produced for each analyzed sample to be considered when their activities are calculated. Practically, the suggested method was verified and succeeded in improving the obtained results.

Radiological impacts of natural radioactivity in Abu-Tartor phosphate deposits, Egypt.

Phosphate and environmental samples were collected from Abu Tartor phosphate mine and the surrounding region. The activity concentration of 226Ra (238U) series, 232Th series and 40K were measured using a gamma-ray spectrometer. The activities of uranium isotopes (238U, 235U and 234U) and 210Pb were measured using an alpha spectrometer and a low-background proportional gas counting system, respectively, after radiochemical separation. The results are discussed and compared with the levels in phosphate rocks from different countries. It seems that the Abu Tartor phosphate deposit has the lowest radioactivity level of exploited phosphate of sedimentary origin. 226Ra/238U, 210Pb/226Ra, 234U/238U and 226Ra/228Ra activity ratios were calculated and are discussed. The radioactivity levels in the surrounding region and the calculated exposure dose (nGy/h) will be considered as a pre-operational baseline to estimate the possible radiological impacts due to mining, processing and future phosphate industrial activities. To minimize these impacts, the processing wastes should be recycled to the greatest possible extent.

Diagnostic value of serum creatine kinase and lactate dehydrogenase isoenzyme determinations for monitoring early cardiac damage in rats.

Serum activities of creatine kinase (CK, EC 2.7.3.2) and CK isoenzymes, lactate dehydrogenase (LDH, EC 1.1.1.27) and LDH isoenzymes, alpha-hydroxybutyrate dehydrogenase (alpha-HBDH, no EC) and the LDH/alpha-HBDH ratio were studied following a single s.c. application of 5-250 mg isoproterenol/kg body weight (b.w.) in rats. Measurements of the serum enzymes and histological and enzyme-histochemical examinations of hearts were performed 2, 4, 6, 8 and 24 h after treatment. A drastic increase in serum levels of the isoenzymes CK-MB, LDH1, LDH2 and alpha-HBDH and decrease in the ratio LDH/alpha-HBDH were observed from 2 h onwards after isoproterenol application in all dose groups, the maximum effect being after 4-8 h. Focal cellular injury in the myocardium could also be observed from 2 h onwards after isoproterenol application by an enzyme-histochemical method using nitro blue tetrazolium (NBT) whereas the earliest histological alterations using haematoxylin and eosin (HE) stain could be detected 6 h after treatment. A dose-dependent effect as to enzyme values as well as to myocardial necrosis was observed 24 h after isoproterenol application. No kidney damage could be detected on the basis of serum urea nitrogen and histological examinations. Thus, measurement of serum activities of CK-MB isoenzyme alone or LDH1-2 isoenzymes in combination with other tests to exclude kidney damage are valuable indicators of cardiac lesions in rats.