Materials Science Forum Vol. 1104

Abstract: Torsional vibration analysis of the axially functionally graded carbon nanotubes has been carried out. Nonlocal stress gradient elasticity theory has been used in continuum mechanics model of the carbon nanotube. Variation of the material properties of the axially graded nanostructure has been assumed in exponential form. Differently from the majority of literature works, viscous damping and nonlocal parameters have been assumed in grading form. Energy functional for the carbon nanotube has been achieved with minimum potential energy principle and weak form solution has been obtained with the Ritz Method. Effects of material grading, nonlocality and viscoelasticity to the torsional dynamics of axially graded carbon nanotube have been investigated. Results of the present work could be useful in modeling and production of axially functionally graded nanostructures.

Abstract: The method of powder metallurgy for the manufacture of titanium products has the advantages of low cost of raw titanium, short technological process, low energy consumption, and less equipment investments. This allows to significantly reduce the total costs. The method is a potential technology to manufacture inexpensive products from titanium alloys. Due to its high strength, low specific weight and high corrosion resistance, titanium is widely used in aerospace and automotive industries and biomedicine. Among various applications of titanium, tube- and disc-shaped products from titanium powder are essential. The paper presents the results on the investigation of products made of titanium powder by the method of magneto-pulse pressing. Titanium powders with a particle size of 160-1000 mm produced by grinding titanium sponge and its powder compositions were used in the investigation. Investigation results on microstructure and porosity are also discussed. The mean porosity of the samples after sintering was 25-28% for products of 4-6 mm thick. With increasing thickness, the porosity increases to 35% and more, while it was non-uniform both over the cross-section of a tube-shaped product and along its length. The outer surface of the product was found to have a looser microstructure. This can be explained by the application of an intermediate fusible layer to the inner wall of the shell, which makes easier the removal of the shall after pressing. The studies generally confirm the possibility tof using the magneto-pulse pressing of titanium powders in shells to manufacturesmall product batches.

Abstract: NiZnFe₂O₄/SiO₂ was successfully synthesized by green-synthesis method using moringa oleifera with various concentrations of 0%, 5%, 10%, 15%, 20%, 30% and 50%. X-Ray diffraction spectra showed that the crystal structure of NiZnFe₂O₄/SiO₂ has a mixed cubic spinel structure. Fourier-transform infrared spectra indicated the C-H functional group at 2374-2378 cm^-1 which identified that green synthesis has been successfully carried out, Si-O-Si (siloxane) at 1072-1100 cm^-1 which was confirmed as NiZnFe₂O₄/SiO₂ which allows modification silica was successfully encapsulated in NiZnFe₂O₄/SiO₂ confirmed by the presence of Si-O-Si groups at 1065-1086 cm^-1. The result of the vibrating sample magnetometer NiZnFe₂O₄/SiO₂ showed saturation magnetization and coercivity was 9-18 emu/g and with at 44-50 Oe respectively, so it is detected as superparamagnetic. The UV-Vis absorbance spectrum of NiZnFe₂O₄/SiO₂ for all concentrations was at 194 nm with a band gap of energy ranging from 3.14 to 3.34 eV which indicates good absorption. The Photocatalytic process with NiZnFe₂O₄/SiO₂ using organic dye methylene blue was available to do up to 94%.

Abstract: The photocatalytic activity of NiZnFe₂O₄/TiO₂ core-shell gg nanocrystalline was carried out. The NiZnFe₂O₄/TiO₂ core-shell was synthesized using co-precipitation method with various concentrations 1:0, 1:1, 1:2, 1:3, 1:4, and 1:5. X-ray diffraction spectra pattern showed crystallite size at various concentrations 1:0, 1:1, and 1:3, which of 5.00 nm, 4.90 nm, and 10.81 nm, respectively. The morphology of NiZnFe₂O₄ nanocrystalline was characterized by transmission electron microscopy which confirmed that the sample undergoes agglomeration with not uniform particle shape. The average particle size of the nanocrystalline was 10.26 nm. Fourier transform infra-red showed functional groups such as Ti-O-Ti, M-O_tetra, and M-O_octa at 1473.62, 563 - 586, and 401- 424 cm^-1. In addition, the presence of Ti-O-Ti and M-O functional groups indicates NiZnFe₂O₄/TiO₂ core-shell has been formed. The absorbance spectrum of the NiZnFe₂O₄/TiO₂ core-shell has an energy band gap in the range of 2.1 – 3.3 eV. The results of the Vibrating sample magnetometer showed saturation magnetization and coercivity values ​​in the range of 12.4 – 22.9 emu/gr and 47 - 55 Oe, which were correlated as soft magnetic properties. NiZnFe₂O₄/TiO₂ was successfully degraded Methylene Blue that reach 99.8% under UV light irradiation. The addition of TiO₂ increases degradation, TiO₂ acts as a trapping state that inhibits electron-hole recombination which can prolong the reaction time between free electrons and MB solution molecules. This study revealed the high potential of NiZnFe₂O₄/TiO₂ core-shell nanocrystalline in photocatalytic application.

Abstract: Arsenic in the water bodies being a serious menace for human and living organisms. To tackle this arsenic contaminant, a series experiments were conducted on biosorption of arsenic using isolated from soil and water sample of Taptapani Hotspring of Odisha, India. Out of the various collected microorganisms three isolates viz. Exiguobacterium sp.(SSB11), Alcaligenesfaecalis DZ2(SSB17) and Lysinibacillussphaericus SI-3(SSB58) possess better affinity towards heavy metals. By exploring this, the consortium of these microorganisms was chosen for bioremediation of As(III) from waste water. As revealed from experiments, the maximum adsorption capacity of the consortium isolates were observed to be 51 g/g. Further, the biosorption kinetics were tested with two robust isotherms viz. Freundlich and Langmuir, thereby revealing better agreement with the Freundlich isotherm.