Papers by Keyword: Nanotechnology

Abstract: The main goal of the work is to identify the advantages of fast reactors when using nanotechnology in the manufacture of core materials. The research methods are based on the adaptation of known technologies (including powder metallurgy) to the design of fast reactors and on the numerical simulation of physical processes carried out using computer programs for the analysis of emergency conditions of fast reactors (including anticipated transient without scram - ATWS). The results of the research show that the use of structural materials based on steels hardened by nanooxides in combination with fundamentally new types of fuel based on composite materials can significantly improve the safety of nuclear technics. Sintered mixtures of ceramic microgranules (oxide, nitride) and nanoadditives of metallic beryllium or uranium are considered as nuclear fuel. Such composite nuclear fuel improves reactor safety and power. The following types of composite fuel were analyzed: mixed oxide with additives of a beryllium or uranium nanopowder, mixed mononitride with additives of a beryllium or uranium nanopowder. Most preferably, a ceramic-metal pellet fuel based on mononitride microgranules and uranium metal nanopowder. The use of such fuel (with a volume fraction of metallic uranium up to 20%) significantly increases the safety of the reactor, combining the advantages of metal and ceramics and completely neutralizing their disadvantages. The proposed materials are of practical importance in the development of new concepts of nuclear technics, in the transition to large-scale nuclear power and high-power reactors. The use of a new cermet-based composite fuel increases the power of the reactor and significantly increases the safety of the reactor.

Abstract: MnZn Spinel ferrite with the chemical formula of Mn_xZn_1-xFe₂O4 (x = 0, 0.25, 0.5, 0.75, 1.0) were synthesized by a sol-gel auto-combustion method. Structural and morphological properties of synthesized samples were characterized by X-ray diffraction (XRD) and Field Emission Microscopy (FESEM). XRD patterns revealed characteristic peaks corresponding to spinel Mn-Zn ferrite structures. In addition, the structural analysis demonstrates that the average crystallite size of the synthesized samples varied in the range of 30.0-40.0 nm. The FESEM micrographs reveal agglomerated particles with particles size ranging from 60-80nm. Interfacial tension (IFT) and contact angle measurement for MnZn ferrite nanofluids were performed. The results showed that the use of MnZn ferrite nanofluid significantly decrease the oil-water IFT and contact angle.

Abstract: PANI was prepared in-house, characterized and utilized in the sorption of calcium, magnesium, iron, and copper in aqueous solution. The objective of this research was to evaluate adsorption of metals in mono and multi-metal in aqueous solutions onto PANI. Literature has it that, there is no record for competitive sorption of metals by PANI. The characterization of the prepared PANI confirmed with other literature that it was the Emeraldine PANI that was prepared. The results obtained after the multi metal adsorption experiment showed that PANI has a good performance in the removal of copper, iron, calcium, and magnesium, and can be credited to its' large surface area since it is a nanomaterial. Testing for the selectivity showed that the prepared nanoPANI adsorbed 95.2% of lead, 93.8% of copper and 75.8% of the iron in the single metal system.

Abstract: The paper considers the identification of properties of real gases and creation of nanomaterials on the basis of molecular and kinetic theory of gases, namely the Boltzmann equation. The collision term of the Boltzmann equation is used in the algorithm for the identification of transport properties of media. The article analyses the uniform convergence of improper integrals in the collision term of the Boltzmann equation depending on the conditions for the connection between the kinetic and potential energy of interacting molecules. This analysis allows to soundly identify the transport coefficient in macro equations of heat and mass transfer.

Abstract: The degree of unsaturation of hydrocarbon chains in the lipid diversity of biological membrane will greatly influence the membrane protein function. Lipid-lipid interactions in the membrane domain are crucial in the development of novel liposomal nanocarrier as the stability and function of liposomes are important points to be considered. The embedded therapeutic proteins are dependent on lipid membrane composition and their physical properties. In this study, we elucidated lipid-lipid interactions in the biological membrane domain with energetic quantitative data by mixing any two C18 fatty acids namely, stearic acid (SA), oleic acid (L1), linoleic acid (L2), and linolenic acid (L3) in Langmuir-Blodgett trough with water subphase. In general, SA has a saturated hydrocarbon chain; meanwhile, L1, L2 and L3 have increasing degree of unsaturation in their respective hydrocarbon chain. The tail-to-tail interactions were studied by the combinations of SA/L1, SA/L2, SA/L3, L1/L2, L1/L3 and L2/L3 at various mole ratios ranging from 9:1, 8:2, 7:3 ... to 1:9. Among the mixtures of C18 fatty acids, L2/L3 is considered as the energetically stable at the optimum amount of X_L2 and X_L3 = 0.5 respectively, at all discrete surface pressure.

Abstract: In this work, we described an effective approach to prepare nanofibrillated cellulose (NFC) with cellulose II structure under mild condition. Firstly, the water hyacinth (WH) was subjected to a series of a two-step chemical treatment, NaOH/urea pretreatment, and mechanical defibrillation at different defibrillation times. After that, raw water hyacinth fiber (RWF), bleached water hyacinth fiber (BWF), NaOH/urea pretreated water hyacinth fiber (PWF), and the resulting NFC were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), X-ray diffractometry (XRD) as well as rheological measurements. It was found that RWF and BWF exhibited cellulose I crystal structure, whereas PWF and the obtained NFC possessed cellulose II crystal structure. FTIR analysis confirmed the evidence that no other chemical reactions preferentially occurred during both NaOH/urea pretreatment and mechanical defibrillation. As evidenced by rheological properties analysis, the NFC aqueous suspension with a gel-like structure demonstrated a shear-thinning behavior. The obtained NFC could potentially be utilized as a reinforcement for polymeric composites.

Abstract: In a promising nanoelectronics device, namely, memristor based on metal oxides, there are many intermediate states with different conductivity between the limits of highly conductive and low-conducting states. These intermediate states can be used in the processes of associative learning of a neural network based on memristor synapses and simultaneous processing of input pulses, which consists in their weighing and summation in the neuroprocessor. By the method of simultaneous magnetron sputtering of two cathodes in a reactive oxygen environment, thin films of mixed oxides with a different mole ratio of titanium and aluminum were obtained. A method for obtaining a mixed oxide with a specified metal fractions by controlling the sputtering rates of cathodes using acoustic piezoelectric sensors is described. It is shown that the introduction of Al into titanium oxide improves the electrophysical characteristics of the memristor. The existence of an optimal fraction of Al dopant maximizing the memristor resistance ratio of the high-resistive and low-resistive states is established. The results indicate that the method of reactive magnetron deposition of mixed metal oxide by simultaneous sputtering of two cathodes provides a more uniform distribution of elements across the thickness of the active layer compared with the atomic layer deposition method. The uniform distribution is necessary to improve the stability of the memristor. It can be expected that in the memristors on mixed oxides Ti_xSc_1-xO_y, Hf_xSc_1-xO_y, Hf_xY_1-xO_y, Hf_xLu_1-xO_y, Zr_xSc_1-xO_y, Zr_xY_1-xO_y, Zr_xLu_1-xO_y an optimal dopant fraction corresponding to the maximally increased ratio of resistances in the high-resistance and low-resistance states will also be observed. Moreover, memristors on films with pure hafnium and zirconium oxides have a much larger range of resistive switching than titanium oxide.

Abstract: Synthesis of nanostructures for industrial usage is a challenge issue since most of the scale up production is not economically suitable. Here we have described two efficient synthesis approaches for copper (II) oxide nanostructures. And, we have compared the methods with current published procedures in terms of time and its impact to the environments. Our simple and environmentally friendly synthesis procedures can produce various Cu (II) oxide nanostructures. We have successfully synthesis Cu (OH)₂, CuO nanowire and CuO nanoparticles. And, they were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction spectroscopy (XRD), Field emission scanning electron microscopy (FESEM), We have also explored the potential of these nanostructure for future development on biomedical applications.

Abstract: A promising rotating arc discharge method has been developed for producing high purity silver carbon nanotube and zinc oxide nanoparticles, to study their capacities for methylene blue (MB) dye removal under different conditions such as contact time, initial methylene blue dye ion concentration, solution pH, and adsorbent dose. The equilibrium isotherm data were analyzed using Langmuir, Freundlich, Temkin isotherms. Correlation coefficients indicated the following order to fit isotherms for silver carbon nanotube: Freundlich > Langmuir > Temkin. On the other hand, for zinc oxide nanoparticles, the following adjustment founded to fit isotherms was: Langmuir > Temkin> Freundlich. Furthermore, separation factors and distribution coefficients of Methylene blue (MB) dye were calculated. Adsorption kinetic data were analyzed using pseudo-first and second -orders and Elovich model. Film and intraparticle Diffusion model were used to investigate Adsorption mechanism. Kinetic studies showed that the adsorption of methylene blue onto silver carbon nanotubes followed Elovich kinetic model, and the rate of adsorption is controlled by the liquid film diffusion model. Adsorption of methylene blue on zinc oxide nanoparticles followed the pseudo-second-order kinetic model, and the rate of adsorption is controlled by the intraparticle diffusion model.

Abstract: In recent years, the development of new procedures and solutions in the field of conservation has been very significant. The purpose of this article is to collect the main contributions of nanotechnology, in its multifunctional solutions applied in heritage, to offer a global vision of the state of the matter for both scientists and restaurateurs.Nanomaterials offer some advantages over traditional products, improved compatibility and efficiency and reducing the use of toxic organic solvents for humans and the environment. Solutions have been developed for both inorganic supports and organic supports for artistic, architectural and archaeological heritage. Especially relevant are the advances in consolidation processes, pH regulation and / or cleaning / elimination of alteration products on murals, frescoes or stone and in materials composed of cellulose and collagen.Also, nanotechnology is still a recent science and has yet to answer certain questions about its use protocols and reduce the possible risks to health.