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Investigation of fast neutron shielding properties of new polyurethane-based composites loaded with B4C, BeO, WO3, ZnO, and Gd2O3 micro-and nanoparticles

Abstract

The aim of the current research was to study the radiation shielding properties of polyurethane-based shielding materials filled with B4C, BeO, WO3, ZnO, and Gd2O3 particles against fast neutrons. The macroscopic cross sections of composites containing micro- and nanoparticles with a diameter of 10 µm and 50 nm were calculated using MCNPX (2.6.0) Monte Carlo code. The results showed that adding nano-scaled fillers to polyurethane matrix increases attenuation properties of neutron shields compared to micro-scaled fillers for intermediate and fast neutrons. Among the studied composites, WO3 and Gd2O3 nano-composites presented higher neutron cross section compared to others.

Open access
Investigation of the level structure of 90Nb nucleus using the shell model

Abstract

Shell model calculations have been carried out for 90Nb nucleus with the model space in which the valence protons occupy the f5/2, p3/2, p1/2, and g9/2 orbitals and the valence neutrons occupy the p1/2, g9/2, d5/2, and g7/2 orbitals. According to the calculated results, the negative parity is from the contribution of the proton of the f5/2, p3/2, and p1/2 orbits. The moderate spin states of 90Nb are mainly due to the excitation of protons from the f5/2 and p3/2 orbits to the p1/2 and g9/2 orbits across the Z = 38 subshell closure, and the high spin states arise from the excitation of a single neutron from the g9/2 orbit into the d5/2 orbit across the N = 50 shell closure.

Open access
Janus – A New Approach to Air Combat Pilot Training

Abstract

Advanced jet training still relies on old concepts and solutions that are no longer efficient when considering the current and forthcoming changes in air combat. The cost of those old solutions to develop and maintain combat pilot skills are important, adding even more constraints to the training limitations. The requirement of having a trainer aircraft able to perform also light combat aircraft operational mission is adding unnecessary complexity and cost without any real operational advantages to air combat mission training.

Thanks to emerging technologies, the JANUS project will study the feasibility of a brand-new concept of agile manoeuvrable training aircraft and an integrated training system, able to provide a live, virtual and constructive environment. The JANUS concept is based on a lightweight, low-cost, high energy aircraft associated to a ground based Integrated Training System providing simulated and emulated signals, simulated and real opponents, combined with real-time feedback on pilot’s physiological characteristics: traditionally embedded sensors are replaced with emulated signals, simulated opponents are proposed to the pilot, enabling out of sight engagement. JANUS is also providing new cost effective and more realistic solutions for “Red air aircraft” missions, organised in so-called “Aggressor Squadrons”.

Open access
Measurement of 238U, 232Th and 222Rn concentrations in different table oils samples. Determination of committed effective doses received by consumers following the ingestion of table oil.

Abstract

The main objective of our work is to measure 238U, 232Th, 222Rn and 220Rn in different table oil samples using a method based on the use of two types of solid nuclear track detectors: CR- 39 and LR-115 II in order to determine the doses of radiation received by the individuals following ingestion of the samples of table oil studied. Indeed, we have developed an original method based on the determination of the detection efficiencies of CR-39 and LR-115 II solid nuclear track detectors for alpha particles emitted from the uranium 238 and thorium 232 series to evaluate 238U, 232Th, 222Rn and 220Rn concentrations in different table oil samples. We were able to determine doses of radiation due to 238U, 232Th and 222Rn received by individuals of the Moroccan, French, Italy, Spain and Tunisia populations following the ingestion of table oil.

The effective doses committed due to 238U, 232Th, and 222Rn following the ingestion of the table oil by the consumers were determined. The maximum total committed effective dose was found equal to (10±0.7) µSv·y−1 of the Moroccan population, (11.6±0.7) µSv·y−1 of the French population, (10.3±0.7) µSv.y−1 of the Italian population, (10.4±0.5) µSv·y−1 of the Spanish population and (10.5±0.7) µSv·y−1 of the Tunisian population is much lower than the average dose given by the United Nations Scientific Committee on the Effects of Atomic Radiation [1] for ingestion (0.2 to 0.8 mSv·y−1). The results obtained using our method are in very good agreement with those obtained using the model of the International Commission on Radiological Protection

Open access
National Energy and Climate Plans: Importance of Synergy

Abstract

In the modern world, including the European Union, the Baltic States and Latvia, the power industry has a broad definition, area and content, several social life and economic existence, comfort and safety provision. It also covers the following segments: heat/thermal energy, transport/fuel, electricity, energy resources and their types, etc.

More competent and wider synergy among different energy sectors and power industry and other areas provides the option to solve the global problems, for example, the mitigation of climate changes and the provision of energy sustainability by reducing the production of greenhouse gases, increasing the use of renewable energy sources, achieving higher energy efficiency and providing the careful use of energy resources. The results of synergy are of economic importance; they provide the efficiency and competitiveness of costs.

In this paper, the necessity of synergy between renewables and conventional generation and synergy among energy sectors are considered to achieve the dimensions of national energy and climate plans.

Open access
New record of Glomeris hexasticha Brandt, 1833 (Diplopoda: Glomerida: Glomeridae) from the Lilyaksko Plateau, North-Eastern Bulgaria

Abstract

The present article reports on the first record of Glomeris hexasticha Brandt, 1833 in the area of Lilyaksko Plateau in North-eastern Bulgaria. The species has been found in three of the researched habitats in the region: LP1 – deciduous forest of common hornbeam (C. betulus); in LP2 – coniferous forest of black pine (P. nigra) and in the located nearby Meadow 1 (LP4), covered with wild wheat grass and single shrubs of common rosehip (R. canina). The research of the Myriapoda fauna of the Lilyak Plateau was conducted from May 2017 to April 2018 and G. hexasticha was established only in the period May – August 2017, and a total of 55 individuals (17 males, 17 female) were collected. The largest number of individuals (24) were registered in June 2017 (17 in LP1, 2 in LP2, and 5 in LP4).

Open access
Nuclear reaction applied to fluorine depth profiles in human dental tissues

Abstract

The nuclear reaction 19F(p, αγ)16O is presented as a valid method to measure the fluorine content in the first superficial layers of teeth. The analysis is performed in-vitro in extracted teeth, both healthy, fluorotic and decayed. It is performed irradiating the tooth with an energetic proton beam and analyzing the emitted high energy alpha particles. The quantitative analysis is performed comparing results with that of a standard sample at a known concentration. The depth profile of fluorine has a maximum content in the first superficial layers. The average concentrations in healthy enamel are of the order of 2 mg/g; it is of about 10 mg/g in fluorotic teeth, and below 0.1 mg/g in decayed teeth. The concentration in the dentine is about 50% lower than in the enamel and the concentrations decrease going from incisors to premolar and to molar teeth. Many results and a literature comparison are presented and discussed.

Open access
Optimization of α-Hydroxyketone and Pyrazine Syntheses Employing Preliminary Reactions of Glucose and Buffer Solutions

Summary

Glucose and selected phosphate buffers have been reacted employing systematic variations in reaction temperature and time (150–160 °C for 60–90 min) to optimize the yield of acetol. This mixture was reacted further with NH4OH, systematically varying reaction conditions and reagent ratios to optimize pyrazine yield. The highest yield of pyrazine was obtained when 1 g of glucose was reacted with 25 mL of buffer at 150–160 °C for 60 min, which in turn was reacted with 1 mL of concentrated aqueous NH4OH at 120–130 °C for 17–18 h. Higher temperatures and higher concentrations of glucose caused a decrease in the yield of pyrazines. The addition of hydrolyzed tobacco-derived F1 protein as a secondary source of nitrogen increased the yield of pyrazines by 2–10% depending on F1 protein concentration. Furthermore, the addition of any α-hydroxyketone, similar in structure to acetol, as a pure reagent to the reaction mixture not only increased the yields of pyrazine by ranging from 25–100 % depending on the reagent concentration, but also significantly altered the qualitative and quantitative distribution of the pyrazines. With all of the reaction parameters examined (reaction time, temperature, reagent ratios, etc.) the most significant impacts on both pyrazine yield and distribution were noted when: 1) glucose was pre-reacted with buffer, 2) hydrolyzed F1 protein was added as a second nitrogen source, and 3) when pure α-hydroxyketones were employed as co-reagents. Use of these reaction parameters was found to dramatically shift the pyrazine distribution toward higher molecular weight resulting in a pyrazine array having more desirable physical and sensory attributes.

Open access
Paraffin Permeability of Synthetic Gypsum Binders Modified by Individual Polymers

Abstract

The paper presents an experimental study of five different gypsum composites taking into account paraffin permeability. The composites consist of synthetic gypsum, paraffin and polymers. The samples were produced from gypsum slurry of mixing ingredients, all in the liquid state. After 7 days of maturing, the condition of the samples was assessed as well as drying time was determined. In the second part, the paraffin tightness of different samples was analysed. The results showed that after three weeks of tests the tightness sample was A4. Other polymers were characterised by lower tightness. The content of polymer had also the effect on the final results, but the direct relation between polymer content and paraffin tightness was not observed.

Open access
Phytochemistry, HPLC profile and antioxidant activity of aqueous extracts of fenugreek (Trigonella foenum graecum L.) seeds grown in arid zones of Algeria

Abstract

Fenugreek is an herb that has the ability to resist multiple environmental insults, pests, diseases and many pathogens through the synthesis of substances allowing this plant protection, these substances are called phytochemical compounds or secondary metabolites. The aim of this study is to characterize these secondary metabolites in the extracts of fenugreek seeds grown in Algeria and compare the phytochemical profile and antioxidant activity of the aqueous extracts obtained by maceration and decoction. We carried out a “phytochemical screening” on both types of extracts in order to highlight the different classes of secondary metabolites and assaying total polyphenols by the method of Follin ciocaltchu, total alkaloids and tannins contained in these aqueous extracts and appreciate their antioxidant activity using the FRAP technique. A characterization of phytochemical molecules of the two types of Fenugreek extracts was done by chromatographic method with HPLC. Several phytochemical groups were identified in the extracts of fenugreek: tannins, saponins, flavonoids, terpenes and reducing nitrogen compounds. Chromatographic analysis of the samples show that 4 phytochemical molecules were identified in the aqueous maceration extract: kaempferol, genistein, vanillin and myrecitine and 3 molecules for the aqueous extract of decoction are: rutin, kaempferol and vanillin. The aqueous extract of decoction was characterized by the total polyphenols content (31.7 ± 0.031 mg GAE / 100 g of extract), total alkaloids (2.12 ± 0.015%) and tannins (9.75 ± 0.06%) that are higher than those obtained in the aqueous extract of maceration: total polyphenols (18.9 ± 0.12 mg GAE / 100g of extract), total alkaloids (1.71 ± 0.02%) and 8.69 ± 0.02% for the tannins. A non-significant difference was marked for antioxidant activity found in both types of extracts (56.90 ± 0.013 mg AAE / 100g decoction extract against 56.37 ± 0.24 mg AAE / 100g maceration extract). In the end we conclude that fenugreek may be a promising plant genetic resource responsible for an important biological activity, except its nutritional and therapeutic properties due to their phytochemical compounds.

Open access