Radiation Shielding Effect of Boron Carbide Aluminum Metal Matrix Composite

Boralyn (Al/B₄C) composite material is produced chiefly of boron carbide and aluminum. Boron Carbide is an important material for the nuclear industry due to high neutron absorption cross-section. This composite is used as shielding materials to absorb neutrons in the nuclear reactors and control road materials. In this study we investigated Al/B₄C composites against gamma radiation. For that purpose, 5 wt.%, 10 wt.%, 15 wt.% and 20 wt.% reinforcement content were investigated. Cs-137 gamma radioisotope source which has 662 keV gamma energy photons were used. For each material, linear and mass attenuation coefficients were calculated. Theoretical mass attenuation coefficients were calculated from XCOM computer code. The theoretical results were compared with experimental results. The results were showed that increasing the amount of Boron Carbide compound content of boralyn composite material decrease the linear and mass attenuation coefficient of material

Influence of seasonality on suicidal hanging in Istanbul, 1979-2012: Associations with gender, age, location and instruments of suicide [İstanbul’daki asi intiharlarinin mevsimsel etkilerinin cinsiyet, yaş, lokalizasyon ve asi materyali açisindan incelenmesi 1979-2012]

Objective: Seasonal variations in deaths by suicide have been reported in many countries. However, in Turkey there is no substantial research on this topic. The aim of this study is to examine the influence of the seasons on suicides by hanging in Istanbul during the period 1979 to 2012 and to assess the associations of seasonal suicide by hanging with gender, age, location and instruments. Material and Method: This paper describes the demographic characteristics of suicidal hanging victims for the past 33 years. A total number of 82871 autopsies were performed in the Council of Forensic Medicine in Istanbul Turkey Morgue Department between 1979 and 2012; 4502 (5.43%) of these deaths occurred as a result of hanging. 4502 suicides by hanging were selected using the study criteria. Results: In this study, most victims were male and the mean age was 37.8 years. Most suicides took place at home but also occurred in prisons, open and built-up areas and workplaces. 455 victims hanged themselves with rope. Inseasonal spring and summer, hangings peaked among total population. The seasonal distribution of the hangings showed a significant difference in both sexes as evidenced by the “goodness of the fit” test. There were no statistically significant seasonal variations of suicidal hanging for age, location and instrument. Conclusion: The results show that the highest rates were observed in the warmest months. This study is an important source of epidemiological data for suicide by hanging. © 2015, Nobelmedicus. All Rights Reserved

An Investigation on the Mass Attenuation Coefficients of W-VC-C and W-VC-TiC-C Composites for Gamma Radioisotopes

In this study, tungsten-vanadium carbide-graphite and tungsten-vanadium carbide-titanium carbide-graphite composites (W-VC-TiC-C) which can be used in high-tech equipment were investigated against different gamma radioisotopes. The composite materials were produced via mechanical alloying method in two groups; one of them includes 93% tungsten (W), 6% vanadium carbide (VC) and 1% graphite (C) which was synthesized during three different alloying times (6, 12, 24 hours). Other group of the samples were composited as 91% tungsten, 6% vanadium carbide (VC), 2% titanium carbide (TiC) and 1% graphite (C) which has also three different alloying times (6, 12, 24 hours). Gamma transmission technique was used in the experiments to investigate the gamma attenuation properties of the composite materials. Linear and mass attenuation coefficients of the samples were determined in the experiments and theoretical mass attenuation coefficients were calculated using widely acknowledged XCOM computer code. The experimental mass attenuation coefficients and calculated theoretical results were compared and evaluated with each other. Results showed that gamma attenuation coefficients of the composite materials dependent on alloying time. It can be concluded that increasing the tungsten ratio causes higher linear attenuation coefficient which decreases with increasing gamma energies

Investigation of helical flow by using tracer technique

The flow through coiled tubes is, in practice, important for pipe systems, heat exchangers, chemical reactors, mixers of different gas components, etc., and is physically interesting because of the peculiar characteristics caused by the centrifugal force. Therefore, it is not so easy to observe flow parameters in the helical pipe experimentally. Tracer techniques are being increasingly used to determine characteristics such as volume flow rate, residence time, dispersion and mixing process in industry. In this study, the flow in the helical pipe was obtained in the laboratory and investigated by using the tracer technique. The experimental system including the helical pipe was set up in the laboratory. In the experiments methylene-blue (C16H17N3S) has been used as the tracer. The experiments were successfully performed with different flow rates and their results were evaluated with the flow parameters