Experimental study of gamma-ray attenuation capability of B2O3-ZnO-Na2O-Fe2O3 glass system.

In the present work, a glass system with developed composition consisting of B2O3, ZnO, Na2O and Fe2O3 samples has been investigated. Glass samples were prepared using the melt quenching method and the density of the system was measured using Archimedes' principle. Spectroscopic analysis using a gamma source and a high-purity germanium detector at four energies of 0.0595, 0.6617, 1.173, and 1.333 MeV emitted from Am-241, Cs-137, and Co-60 were used to determine the attenuation parameters of present glass composites. The sample containing 45 B2O3 + 10 Na2O + 40 ZnO + 5 Fe2O3 (coded BNZF-4) had the highest mass attenuation coefficient (MAC) value at all the energies discussed compared to the other composites. Whoever, the BNZF-1 sample had the lowest value at all ranges of energies. The transmission factors (TF, %) of the manufactured samples were calculated, at 0.0595 MeV (TF, %) values are 32.6429 and 6.4612 for samples BNZF-1 and BNZF-4, respectively. The statistical results demonstrated significantly better to increase the ZnO concentration in the sample, where the percentage of zinc oxide inside the prepared glass samples has the following direction BNZF -4 > BNZF -3 > BNZF -2 > BNZF -1. The significance of this study is that transparent, environmentally harmless glass composites with relatively high density have been prepared that can be used as shielding materials against gamma rays, especially at low energies.

Effects during the cathode polarization of porous silicon.

The large inner surface of porous silicon (pSi) not only provides unique opportunities for introducing various foreign materials into the open pores, but is also responsible for a lot of processes during the pSi cathode polarization. PSi surface and contact effects are considered in the article. The space charge layer induced by both the surface states and the double electrical layer in the solution is shown to have a decisive influence on the electrical conductivity of the silicon skeleton in the pSi layer. Depending on the depletion degree of the pSi skeleton, the electrochemical deposition of metals is possible either on the entire pSi surface or pore filling from the bottom. The erbium hydroxide formation in the process of the cathode polarization of pSi in the solution of erbium salt is shown to have a chemical nature and is stimulated by the alkalization of the cathode space. The formation of erbium-containing deposits occurs by the following mechanism. First, hydrogen is electrochemically reduced at the cathode. This causes the ion imbalance and leads to the alkalinization in the space near the cathode. The alkaline medium creates conditions for the chemical process of the erbium hydroxide formation. Formed as a gel, erbium hydroxide is physically adsorbed on the cathode surface as a film. The components of the solution are necessarily included in the deposit composition. The accompanying oxidation and dehydrogenation effects during the cathode pSi polarization are considered. Moreover, during the pSi oxidation, the solid phase extends in the pore increases the steric factor, which is essential for the formation of internal oxygen bonds. These effects are characteristic features of any pSi cathode treatment. These formation rules are true for any lanthanide. The obtained results open wide prospects for practical application of Er-filled pSi as a promising material for practical biomedical application as prospective electrodes.

Experimental investigation of radiation shielding competence of B2O3-Na2O-Al2O3-BaO-CaO glass system.

Aiming to extend the scope of utilizing glass in radiation shielding, this work investigates the radiation interaction response of a borate-based glass system. Four borate-glass samples of different substituting concentrations of calcium oxide ( 70 - x )B2O3: 10 Na2O : 5 Al2O3 : 15 BaO: x CaO were prepared. To assess the shielding performance of the prepared glass samples, a high-purity germanium detector and different radioactive sources (different energies) were used. Via the narrow beam method, the linear attenuation coefficients (LACs) were experimentally measured. So, the transmission factor (TF), the half-value layer (HVL), the tenth value layer (TVL), the mean free path (MFP), and the radiation protection efficiency (RPE) were calculated for all prepared samples. It was observed that the increase of the concentration of calcium oxide in the proposed borate-based glass samples leads to improve their performance in shielding against radiation. At low energy, the RPE of the samples is almost 100%. However, it was observed that as energy of the radiation source increases, the shielding performance of the samples will decrease. High energy dependence was found when calculating TF, HVL, TVL, and MFP. They were increased with the increase of the energy of the incident photons. At 0.662 MeV, the TF values are equal to 79.26, 79.00, 79.72, and 78.43% for BNABC-1, BNABC-2, BNABC-3, and BNABC-4 in the same oder, respectively. The application of the proposed composition of borate-based glass as a transparent shield against low-energy ionizing radiation was highlighted.

Effect of gelatin concentration on the characterizations and hemocompatibility of polyvinyl alcohol-gelatin hydrogel.

BACKGROUND: The design and fabrication of hemocompatible and low-toxicity formulations remains a challenging task. Hydrogels are of considerable importance for biomedical applications since they are highly compatible with living tissue, both in vivo and in vitro. OBJECTIVE: The present study aimed to develop and evaluate the characterizations and in vitro hemocompatibility of a hydrogel using polyvinyl alcohol and gelatin with different concentrations. METHODS: The gelling process was realized by cross-linking the polyvinyl alcohol and gelatin. The morphological and structural examinations of the synthetic hydrogels were done by scanning electron microscopy (SEM) and X-ray powder diffraction (XRD). The swelling behavior of the prepared hydrogels in water was evaluated. Prothrombin time, activated partial thromboplastin time, and thrombin time were measured, and a hemolysis test was done to evaluate the hemocompatibility of prepared hydrogels. RESULTS: The increase of the gelatin concentration in polyvinyl gelatin hydrogel increases the porosity and enhances the absorptivity of the prepared hydrogel. The measured hematological parameters indicated enhancement of hemocompatibility as the gelatin concentration was increased in the prepared hydrogel. CONCLUSIONS: The results obtained from this study confirm that gelatin was able to improve the properties of the polyvinyl alcohol-gelatin hydrogel and enhance the hemocompatibility. Thus, the prepared hydrogel could be used in a variety of biomedical applications.

Dielectric relaxation and alternating current conductivity of lanthanum, gadolinium, and erbium-polyvinyl alcohol doped films.

Fourier transform infrared (FTIR) spectrum dielectric constant, ε', loss tangent, tan(δ), electric modulus, M*, and ac conductivity, σ(ac), of pure polyvinyl alcohol (PVA) as well as La-, Gd-, and Er-PVA doped samples have been carried out. The dielectric properties have been studied in the temperature and frequency ranges; 300-450 K and 1 kHz-4 MHz, respectively. FTIR measurements reveal that La(3+), Gd(3+), and Er(3+) ions form complex configuration within PVA structure. Two relaxation processes, namely, ρ and α were observed in pure PVA sample. The first process is due to the interfacial or Maxwell-Wagner-Sillers polarization. The second one is related to the micro-Brownian motion of the main chains. For doped PVA samples, α-relaxation process splits into α(a) and α(c). This splitting is due to the segmental motion in the amorphous (α(a)) and crystalline (α(c)) phases of PVA matrix. Electric modulus analysis was discussed to understand the mechanism of the electrical transport process. The behavior of ac conductivity for all PVA samples indicates that the conduction mechanism is correlated barrier hopping.