Investigation of Complex Impedance and Modulus Properties of Nd Doped 0.5BiFeO3-0.5PbTiO3 Multiferroic Composites

0.5BiNdxFe1-xO3-0.5PbTiO3 (x=0.05, 0.10, 0.15, 0.20) composites were successfully synthesized by a solid state reaction technique. At room temperature X-ray diffraction shows tetragonal structure for all concentrations of Nd doped 0.5BiFeO3-0.5PbTiO3 composites. The nature of Nyquist plot confirms the presence of bulk effects only for all compositions of Nd-doped 0.5BiFeO3-0.5PbTiO3 composites. The bulk resistance is found to decreases with the increasing in temperature as well as Nd concentration and exhibits a typical negative temperature coefficient of resistance (NTCR) behavior. Both the complex impedance and modulus studies have suggested the presence of non-Debye type of relaxation in the materials. Conductivity spectra reveal the presence of hopping mechanism in the electrical transport process of the materials. The activation energy of the composite increases with increasing Nd concentration and were found to be 0.28, 0.27, 0.31 and 0.32eV for x=0.05, 0.10, 0.15, 0.20 respectively at 200-275 oC for conduction process.Comment: 22 pages, 12 figures, 2 tables, 34 Referenc

STEREO SELECTIVE SYNTHESIS OF NOVEL PYRAZOLE AND COUMARIN APPENDED BRIDGED PYRANS AS ANTIMICROBIAL AGENTS

Objectives: The aim of the present study was to synthesize a series of novel bridged pyrans as antimicrobial agents.Methods: An isomeric mixture of 3-(4-ethoxy-10-methyl-8-oxo-2-phenyl-4,8-dihydro-2H-pyrano[3',2':6,7]chromeno[4,3-c]pyrazol-6-yl)-1-phenyl-1H-pyrazole-4-carbaldehydes, 2(a-f) and 3-(4-ethoxy-8-methyl-10-oxo-2-phenyl-4,10-dihydro-2H-pyrano[2',3':5,6]chromeno[4,3-c]pyrazol-6-yl)-1-phenyl-1H-pyrazole-4-carbaldehydes, 3(a-f) were synthesized by the reaction of 3,3'-(7-hydroxy-4-methyl-2-oxo-2H-chromene-6,8-diyl)bis(1-phenyl-1H-pyrazole-4-carbaldehyde) 1(a-f) and ethyl alcohol in the presence of conc. H2SO4. The synthesized compounds were evaluated for their antimicrobial activity.Results: The structures of the new bridged pyran analogues 3-(4-ethoxy-10-methyl-8-oxo-2-phenyl-4,8-dihydro-2H-pyrano [3',2':6,7] chromeno [4,3-c]pyrazol-6-yl)-1-phenyl-1H-pyrazole-4-carbaldehydes, 2(a-f) and 3-(4-ethoxy-8-methyl-10-oxo-2-phenyl-4,10-dihydro-2H-pyrano [2',3':5,6] chromeno[4,3-c]pyrazol-6-yl)-1-phenyl-1H-pyrazole-4-carbaldehydes, 3(a-f) were confirmed by spectral studies and elemental analysis. The compounds 2e and 3e were having-CONH2 substitution and 2f and 3f were having-CSNH2 substitutions in the pyrazole rings showed antibacterial at minimum concentrations against all the tested organisms.Conclusions: Results of the antimicrobial activity reveal that some of the synthesized compounds act as potential antimicrobial agents against different fungal and bacterial organisms.Â

Interface induced perpendicular magnetic anisotropy in Co/CoO/Co thin film structure: An in-situ MOKE investigation

Co /CoO/Co polycrystalline film was grown on Si (001) substrate and magnetic properties have been investigated using in-situ magneto-optic Kerr effect during growth of the sample. Magnetic anisotropy with easy axis perpendicular to the film surface has been observed in top Co layer, whereas bottom layer was found to be soft with in-plane magnetization without any influence of top layer. Ex-situ in-plane and out-of-plane diffraction measurements revealed that the growth of Co on oxidized interface takes place with preferential orientation of c-axis perpendicular to the film plane, which results in the observed perpendicular magnetic anisotropy. Texturing of the c-axis is expected to be a result of minimization of the interface energy due to hybridization between Co and oxygen at the interface.Comment: 9 pages, 3 figures, under review in IOP journa

STEREO SELECTIVE SYNTHESIS OF NOVEL LIGNAN INTERMEDIATES AS ANTIMICROBIAL AGENTS

Objectives: The aim of the present study was to synthesize a series of new lignan intermediates as potential antimicrobial agents.Methods: Substituted benzene and aromatic acids or acid chlorides were converted to benzophenones 1(a-f). The benzophenones 1(a-f) on Stobbe condensation with and diethyl succinate in the presence of potassium t-butoxide yielded 4-(4-aryl)-4-(4-aryl)-3-ethoxycarbonyl-but-3-enoic acids (2a, 2f) and a mixture of E and Z-isomers of 4,4-diaryl-3-ethoxycarbonyl-but-3-enoic acids 2(b-e) and 3(b-e) in relatively good yields. The synthesized compounds were tested for their antimicrobial susceptibility against different fungi and bacteria species.Results: The Stobbe condensation of benzophenones 1(a-f) and diethyl succinate in the presence of potassium t-butoxide yielded 4-(4-aryl)-4-(4-aryl)-3-ethoxycarbonyl-but-3-enoic acids (2a, 2f) and a mixture of E and Z-isomers of 4,4-diaryl-3-ethoxycarbonyl-but-3-enoic acids 2(b-e) and 3(b-e) in good yields. The compounds 1a and 1f yielded only 2a and 2f but not 3a and 3f due to symmetrical substitution in the aromatic rings. The structures of the new lignan intermediates were confirmed by spectral studies and elemental analysis.Conclusions: Results of the antimicrobial activity reveal that some of the compounds particularly 2c, 2d, 3c and 3d act as potential antimicrobial agents different fungal and bacterial organisms.Â

Modelling of Cascade Fin Aerodynamics Near Stall using Kirchhoff's Steady-state Stall Model

Nonlinear longitudinal aerodynamics associated with cascade fins at high angles of attack near stall has been modelled using Kirchhoff's formulation. Grid fins are a relatively recent development in guided missile technology. In this paper, a new category of grid fins, nomenclatured as cascade fins, has been proposed. In cascade fin design, an appropriate selection of gap-to-chord ratio and the number of planar members lead to desired stall angle and acceptable overall lift coefficient, respectively. Kirchhoff's steady-state stall model has been validated on wind tunnel data generated for Cascade fins having rectangular airfoil cross-section. National Wind Tunnel Facility (NWTF) of IIT, Kanpur, was used to generate the wind tunnel data consisting of the variation of lift coefficient with angle of attack. The cascade fins were tested to generate the data by varying gap-to-chord ratio and number of planar fins. The cascade fins with rectangular cross-section were tested with and without end plates. Kirchhoff's steady-state stall model was applied to wind tunnel data of cascade fins for modelling flow separation point and maximum likelihood method was used to estimate the parameters characterising stall characteristics. The effects of end plates, variation of number of fins and gap-to-chord ratio on parameter estimation were also studied. It has been observed that Kirchhoff's steady-state stall model could advantageously be applied to model nonlinear aerodynamics associated with cascade fins at high angle of attack.Defence Science Journal, 2011, 61(2), pp.157-164, DOI:http://dx.doi.org/10.14429/dsj.61.48

Evaluation of Potato Genotypes for Processing Traits in Late Autumn

The present study was undertaken to evaluate potato genotypes for their suitability for processing when grown under different crop durations, i.e., E1 (80 days' crop duration), E2 (100 days' crop duration) and E3(120 days' crop duration). Among the three durations studied, E3 yielded the highest processing-grade yield (q/ha), followed by E2 and E1. The crop in E3 also exhibited high dry-matter content and low levels of reducing sugars compared to that in the other crop durations, which is desirable for processing. Among the cultivars under study, Kufri Badshah, Kufri Anand, Kufri Bahar, Kufri Chipsona-1, Kufri Chipsona-2, Kufri Ashoka and Kufri Jawahar gave the highest total tuber-yield. However, for processing-grade yield, cvs. Kufri Badshah, Kufri Chipsona-1 and Kufri Jawahar yielded significantly better than the mean, but cv. Kufri Chipsona-1 was the one found suitable for processing due to its high dry-matter content (22.07%), while, the other cultivars were found suitable for table purpose alone. Though cv. Kufri Chipsona-1 yielded higher (309.39 q/ha), its performance could not be predicted under various conditions owing to the data on regression coefficient (being less than one), and a significant deviation from regression. Cultivars Kufri Chipsona-1 and Kufri Chipsona-2 were found to be suitable for processing, with high tuber- and processing-grade yield, high dry-matter content, low amount of reducing sugars and phenols in the crop durations E2and E3. Both these cultivars produced chips of acceptable colour in all three crop durations

Effect of Twin Vertical Stabilizers on Lateral Directional Static Stability of an Aircraft – A Computational Study

The advantages of twin vertical Stabilizers over a single vertical Stabilizer of an aero plane are the rationale for this study. For conventional aero planes, the use of double vertical Stabilizers is being considered. The contribution to lateral stability has been examined for this application. XFLR5 software was used to conduct the overall analysis. The analysis was conducted for a single vertical Stabilizer as well as twin vertical Stabilizers, and the findings were compiled and correlated. It is critical to be able to fully explain and evaluate the stability and control parameters. It is crucial to understand the relationship between the aerodynamics of the airframe and its stability characteristics in order to increase flight endurance and deployment effectiveness. The stability analysis based on the dynamic model of the twin boom vertical Stabilizer is presented in this paper. The lateral-directional stability of an aero plane with a single vertical tail is determined to be 20% more efficient than that with twin boom vertical Stabilizers. The trim condition is moderately satisfied by an aircraft with twin vertical Stabilizers