Concrete is a material which widely used as a neutron shielding and in building construction such as nuclear power stations, particle accelerators and medical hospitals. Concrete is very significant for neutron shielding, because of concrete is contain of some elements (hydrogen, iron etc.) to moderate the fast neutrons which are very penetrative. Boron increases the neutron shielding effectiveness of concretes, since the boron isotope 10 B has a high capture cross-section for thermal neutrons (over 3800 barns). Boron can be added to concrete different ways such as addition of boron to the water used in concrete or addition of boron containing natural minerals. Neutron shielding capabilities of the sample can be described by total neutron macroscopic cross-section ( t ). It is the sum of the cross-sections for all the neutron-interaction processes such as the elastic and inelastic scattering reactions and neutron capture reactions ((n,),(n,)). In this study, the effect of addition boron and colemanite on the total macroscopic cross section of Portland concrete was investigated. Colemanite is one of the most important boron minerals and Turkey has the largest colemanite reserves in the world. Its compact formula is Ca 2 B 6 O 11 •5(H 2 O). Also, colemanite can be used for shielding fast and thermal neutrons, since it includes both of hydrate and boron. In experiments, 241 Am-Be neutron source with 74 GBq activity were used in. Average neutron energy of this source is approximately 4.5 MeV. BF 3 detector with diameter 2.54 cm and length of 28 cm was used for counting neutrons. Also, Monte Carlo simulations were done for comparison of macroscopic cross section experimental results. Besides total macroscopic cross sections, absorbed doses and deposited energies by low energy neutron interactions were calculated using MCNP4C2 Monte Carlo code. The results have been compared with the standard shielding material of paraffin. Also, half-value layer (HVL) and tenthvalue layer (TVL) were calculated and compared.
Mechanical properties" are crucial for biodegradable and/or nonbiodegradable materials used in tissue engineering applications. In this study, bio-hybrid films were produced by using both Bifidobacterium animalis subsp. lactis BB-12 probiotic strain and Bifidobacterium infantis in combination with sodium alginate (SA), which demonstrates biocompatibility and facilitated gelation properties. Bio-hybrid films were characterized by using different methods. Based on the spectroscopic and mechanical analysis, it was found that mechanical strength increased in films produced by adding Bifidobacterium infantis in SA while this increase was relatively lower as compared to those containing Bifidobacterium animalis subsp. lactis BB-12 as crosslinking ratio increases. Besides, bacteria contained in bio-hybrid films increased the percentage of amorphous zone of SA in SA/bacteria films, which reduced the crystallinity ratio. This indicated that crystalline chains contained in the structure of SA are degraded by bacteria.
Magnesium borates are one of the major groups of boron minerals that have good neutron shielding performance. In this study, dehydrated magnesium borates were synthesized by solid-state method using magnesium oxide (MgO) and boron oxide (B2O3), in order to test their ability of neutron shielding. After synthesizing the dehydrated magnesium borates, characterizations were done by X-ray Diffraction (XRD), fourier transform infrared (FT-IR), Raman spectroscopy, and scanning electron microscopy (SEM). Also boron oxide (B2O3) contents and reaction yields (%) were calculated. XRD results showed that seven different types of dehydrated magnesium borates were synthesized. 1000°C reaction temperature, 240 minutes of reaction time, and 3 : 2, 1 : 1 mole ratios of products were selected and tested for neutron transmission. Also reaction yields were calculated between 84 and 88% for the 3 : 2 mole ratio products. The neutron transmission experiments revealed that the 3 : 2 mole ratio of MgO to B2O3neutron transmission results (0.618–0.655) was better than the ratio of 1 : 1 (0.772–0.843).
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