Ulexite/HDPE-Bi2O3/HDPE layered composites for neutron and gamma radiation shielding.

In this study, 5, 10, and 15 wt% ulexite (NaCaB5O6(ΟH)6·5H2O, hydrated sodium calcium borate hydroxide) and 15 wt %Bi2O3 filled high density polyethylene (HDPE) composite materials were fabricated through conventional melt-extrusion processing techniques in the form of a layered structure in order to absorb both neutron radiations and the secondary radiations resulting from neutron induced reactions. In the layered structure, HDPE was used to slow down neutrons, while ulexite and Bi2O3 were used to capture thermal neutrons and secondary gamma radiations, respectively. The properties of ulexite/HDPE and Bi2O3/HDPE composites were investigated through scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA). The mechanical properties (tensile and hardness) of composite materials were also investigated. The results showed that the addition of ulexite and Bi2O3 particles does not change the thermal and mechanical properties of the HDPE composites significantly. Total macroscopic cross-section of the composites was determined using a 239Pu-Be (α,n) neutron source, while their linear and mass attenuation coefficients were determined using a137Cs gamma-ray source. The results show that ulexite filled HDPE composites enhance neutron shielding property and Bi2O3 filled HDPE composites provide good shielding performance for gamma rays.

Determination of radioactivity level of water supply network in Trabzon province, Turkey.

In the present study, the radioactivity levels of water samples collected from the main water supply network in Trabzon province and districts and soil samples taken from the vicinity of the water network were measured. An Alphaguard-PQ2000 radon gas detector was used to determine the seasonal radon gas level in the water samples. An HPGe detector was used to determine the level of radioactivity in soil and water samples. The average concentration of 222Rn in drinking water ranges from 0.56 ± 0.51 to 13.3 ± 5 Bq L-1. In water samples, average gross alpha and gross beta values were measured as 8 ± 1 and 43 ± 1 mBq L-1, respectively. The average concentrations of 238U, 232Th, 137Cs, 40K radionuclides in soil were measured as 51 ± 2, 21 ± 2, 16 ± 1, 28 ± 7 Bq m-3, respectively. The average concentrations of 238U, 232Th, 137Cs, 40K radionuclides in drinking water were measured as 147 ± 5, 25 ± 2, 77 ± 2, 12 ± 2 mBq L-1, respectively. When the radon concentrations for drinking water were examined, it was found that the radon concentration of the three samples was above the limit value (11 Bq L-1) allowed by the US-EPA for drinking water. All other results are below the limit values.

Radioactivity measurements and risk assessments of spa waters in some areas in Turkey.

The current study presents the results of the activity of radionuclides in spa waters, and evaluates their radiological influences on the population consuming these waters in the Central and Eastern Black Sea regions of Turkey. Since these waters are used for therapy and consumption purposes unconsciously, their radiological impact on the people was computed by taking into consideration the annual intake through ingestion of 226Ra, 232Th, 40K, 137Cs and 222Rn. The mean activities were estimated to be 11.35 for gross alpha, 6.23 for gross beta, 2.96 for 226Ra, 0.42 for 232Th, 0.069 for 137Cs, 0.19 for 40K, and 267 Bq L-1 for 222Rn, respectively. The estimated effective doses from spa water were found to be 49.77 µSv a-1 (226Ra), 5.95 µSv a-1 (232Th), 0.07 µSv a-1 (137Cs), 0.83 µSv a-1 (40K) and 56.03 µSv a-1 (222Rn). These values were evaluated and compared with related verified values from literature. Also, physico-chemical characterizations of spa water samples considered in the current study were investigated. This study would be useful for consumers and official authorities for the assessment of radiation exposure risk due to usage of the considered spa waters.

The Effect of Stent Cell Geometry on Carotid Stenting Outcomes.

PURPOSE: The aim of this study was to investigate the effect of stent cell geometry on midterm results of carotid artery stenting (CAS). MATERIALS AND METHOD: One hundred fifty-five patients underwent CAS between February 2010 and December 2012. Ninety-one open- and 84 closed-cell stents were used in this non-randomized, retrospective study. Periprocedural complications were defined as the ones happened during the procedure or within 30 days afterwards. Starting from the 6th month after the procedure, in-stent restenosis was detected with multidetector computed tomography angiography and classified into four groups from focal restenosis to occlusion. RESULTS: Eleven complications were encountered in the periprocedural period (four on the open- and seven on the closed-cell group). Total complication rate was 6.3% (11/175). No significant difference was detected in terms of periprocedural complications between two groups (p = 0.643). There was statistically significant difference between stent design groups in regard to radiological findings (p = 0.002). Sixteen of open-cell stents and three of closed-cell stents had focal restenosis. One closed-cell stent had diffuse proliferative restenosis and one open-cell stent had total occlusion. CONCLUSION: In-stent restenosis was more common in open-cell stent group, which have larger free cell area than closed-cell stents. Although our radiologic findings promote us to use closed-cell design if 'possible', no difference was detected in terms of clinical outcomes.

A case of hyperkinetic movement disorder associated with LGI1 antibodies.

Encephalitis associated with leucine-rich glioma inactivated 1 (LGI1) antibodies is often encountered in elderly male patients and may infrequently present with isolated syndromes. A 6-year-old boy was admitted with acute onset severe oral and facial stereotypic and choreiform movements. On his neurologic examination, he had repetitive and rhythmic movements in orolingual muscles including tongue protrusion, limb chorea and minimal facial stereotypic movements. Anti-streptolysin O (ASO) titers were found severely elevated in several measurements. Well-characterized antibodies against ion channels and synapse proteins were negative whereas LGI1 antibody was positive in both serum and CSF. Marked clinical improvement was observed after immunotherapy. Here, we present the first pediatric case with LGI1 antibody associated hyperkinetic movement disorders and emphasize the importance of investigating neuronal autoantibodies in patients with isolated and treatment resistant movement disorders.