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Nano-sized BiFeO3 were synthesized by sol-gel auto combustion method and report the effect of different annealing temperature (400 °C, 500 °C, 600 °C) on phase formation, morphology, magnetic and dielectric properties of synthesized bismuth ferrite (BiFeO3) nanoparticles. The phase formation of BFO nanoparticles were confirmed by X-ray diffraction pattern. Further, significant increment in particle size with increasing annealing temperature was estimated by field emission electron microscopy (FESEM). Magnetization curve showed the soft ferromagnetic behavior of the samples annealed at 400 OC and 500 OC that was explained on the basis of disturbance of spiral modulated long range antiferromagnetic order of bulk BFO. Dielectric response revealed decrease in dielectric constant with increasing annealing temperature. BFO is a room-temperature multiferroic material so it is potential candidate for various applications viz. Water waste treatment, gas sensors and photovoltaic cells in rural areas.
This manuscript aims at synthesizing Al2O3-de-ionized water nanofluid and constructing a practical design of self-cooling device that does not require any external power input. Crystalline phase of powder was confirmed by X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) showed the various functional groups and absorption bands and average particle size was calculated to be 58.608 nm by Field Emission Scanning Electron Microscopy (FESEM) annealed at 900K. Experimental investigations were carried out to determine the effect of volume fraction of Al2O3 nanoparticles in the nanofluid on the rate of heat transfer from heat load to heat sink. Temperature of heat load was taken as 80° C. According to our results, cooling by 15°C, 13°C and 12°C was attained when volume fraction of nanoparticles was 1.5%, 1% and 0.5% respectively. The thermal conductivity was also measured and found to be increasing with the concentration of nanoparticles in nanofluid. Hence, indicating the use of nanofluids with suitable concentration in various cooling applications.
FeCoNi(Mn–Si)x (x = 0.5, 0.75, 1.0) high-entropy alloys (HEAs) were successfully synthesized by mechanical alloying (MA), and the effect of Mn and Si in the ferromagnetic alloys on crystal structure and magnetic behavior was thoroughly investigated. XRD, SEM, and TEM were used to investigate the effect of Mn and Si content on the structure of HEAs. The high Mn and Si contents change the structure from the BCC phase to FCC phase. The evolution of surface morphology was discussed on the basis of MA time and content of Mn and Si. The magnetic hysteresis curve confirmed the highest magnetic saturation (Ms) value of 134.21 emu/g for FeCoNi(Mn–Si)1.0 alloy and an appreciably low coercivity (Hc) of 98.07 Oe for FeCoNi(Mn–Si)0.5 alloy. The finite element method (FEM), using COMSOL Multiphysics software, has been used for determining the magnetic flux density (B) on the surface and at the center of the transformer core to determine the performance of the proposed HEAs.
A novel series of nanocrystalline AlCuCrFeMnWx (x = 0, 0.05, 0.1, 0.5) high-entropy alloys (HEAs) were synthesized by mechanical alloying followed by spark plasma sintering. The phase evolution of the current HEAs was studied using X-ray diffraction (XRD), transmission electron microscopy, and selected area electron diffraction. The XRD of the AlCuCrFeMn sintered HEA shows evolution of ordered B2 phase (AlFe type), sigma phase (Cr rich), and FeMn phase. AlCuCrFeMnWx (x = 0.05, 0.1, 0.5 mol) shows formation of ordered B2 phases, sigma phases, FeMn phases, and BCC phases. Micro-hardness of the AlCuCrFeMnWx samples was measured by Vickers microindentation and the maximum value observed is 780 ± 12 HV. As the tungsten content increases, the fracture strength under compression increases from 1010 to 1510 MPa. Thermodynamic parameters of present alloys confirm the crystalline phase formation, and finally structure–property relationship was proposed by conventional strengthening mechanisms.
This study aims to investigate the sliding wear behavior of Al0.4FeCrNiCox (x = 0, 0.25, 0.5, 1.0 mol) high-entropy alloys (HEAs) under oil lubricating conditions at room temperature. Phase and microstructural characterizations of HEAs are performed by utilizing X-ray photoelectron spectroscopy (XRD) and scanning electron microscope (SEM). The compressive yield strength of Al0.4FeCrNiCox (x = 0, 0.25, 0.5, 1.0 mol) HEAs is observed to decrease from 1169.35 to 257.63 MPa. Plastic deformation up to 75% is achieved in the case of Al0.4FeCrNiCox=1 HEA. The microhardness of HEA samples is found to decrease from 377 to 199 HV after the addition of cobalt content from x = 0 to 1.0 mol. Thermal analysis is performed using a differential scanning calorimeter. It is confirmed that Al0.4FeCrNiCox (x = 0, 0.25, 0.5, 1.0 mol) HEAs do not undergo any phase change up to 1000 °C. The specific wear rate of Al0.4FeCrNiCox=1 HEA is observed to be highest in all wear conditions. The worn surfaces were analyzed by SEM with attached energy-dispersive spectroscopy, 3D profiling, and X-ray photoelectron spectroscopy (XPS).
Nitinol, being a shape memory and super elastic alloy, is used in medical industry. Surface modification of nitinol helps to reduce the nickel ion leaching in physiological environment. The purpose of this study is to modify the nitinol surface by the silanization technique and to conduct a comparative investigation with the bare nitinol in the aspect of leaching of nickel ion, hemocompatibility, and in vivo animal response. X-ray photoelectron spectroscopy and energy dispersive X-ray spectroscopy studies confirmed the addition of organofunctional alkoxysilane molecules through the silanization process. The histological study showed the presence of adequate number of osteoblasts in silanized nitinol. The fluorochrome labeling study depicted more new bone formation (8 and 21% higher) in silanized nitinol specimens than bare one at one and three months postoperatively. Radiology and SEM study also proved the better performance of silanized samples. The cumulative in vivo results indicate its suitability as the potential bioimplant in various orthopedic surgical uses.
This paper presents a sequential evaluation of snow microstructure and its associated thermal conductivity under the influence of a temperature gradient. Temperature gradients from 28 to 45 Km–1 were applied to snow samples having a density range 180–320 kgm–3. The experiments were conducted inside a cold room in a specially designed heat-flux apparatus for a period of 4weeks. A constant heat flux was applied at the base of the heat-flux apparatus to produce a temperature gradient in the snow sample. A steady-state approach was used to estimate the effective thermal conductivity of snow. Horizontal and vertical thick sections were prepared on a weekly basis to obtain snow micrographs. These micrographs were used to obtain snow microstructure using stereological tools. The thermal conductivity was found to increase with increase in grain size, bond size and grain and pore intercept lengths, suggesting a possible correlation of thermal conductivity with snow microstructure. Thermal conductivity increased even though surface area and area fraction of ice were found to decrease. The outcome suggests that changes in snow microstructure have significant control on thermal conductivity even at a constant density.
A total of 326 pearl millet accessions selected for fodder traits from the world collection at ICRISAT genebank, India were evaluated in rainy, postrainy and summer seasons to identify promising sources for fodder yield. In rainy season, majority of accessions grew significantly tall, produced thick stems, long and broad leaves compared with postrainy and summer seasons. Total tillers per plant were significantly more in rainy and summer seasons than in postrainy season. Significant (P = 0.05) positive correlations were observed among all traits in all seasons except total tillers, which showed significant negative correlation with all other traits but for a few cases. Accessions of cluster 1 flowered early and produced more tillers per plant, while those of cluster 3 flowered late, grew tall, produced thick stems, more leaves per plant, which were long and broad. Promising sources identified include IP 11839 and IP 11840 for plant height and number of leaves per plant, IP 15710, IP 15735 and IP 15752 for stem thickness and leaf width, and IP 3628, IP 15285, IP 15288, IP 15302, IP 15342, IP 15351, IP 15290, IP 20347 and IP 20350 for total tillers per plant. Further testing of these sources of fodder traits at different locations will be very useful.
The world collection of pearl millet at ICRISAT genebank includes 19,696 landraces. Passport and characterization data of 2,929 accessions belonging to 89 named landraces originating in 15 countries of Africa was used to study the adoption pattern and genetic potential. Out of 89 named landraces under study, 71 were grown in one country, 11 in two countries, six in three countries and one in four countries. Latitude and prevailing climate at collection sites were found as the important determinants of cultivation pattern of landraces. A hierarchical cluster analysis using 12 agronomic traits resulted in five clusters. Cluster 1 for late flowering, short height in rainy season, high tillering and thin panicles; cluster 2 for early flowering; cluster 3 for stout panicles in both the seasons and larger seeds and cluster 5 for longer panicles in both seasons, were found as promising sources. IP 8957, IP 8958, IP 8964 of Iniadi landrace for short height, downy mildew and rust resistance and high seed iron and zinc contents; IP 17521 of Gnali (106.9 ppm) and IP 11523 of Idiyouwe (106.5 ppm) for high seed iron content; IP 17518 of Gnali (79.1 ppm) and IP 11535 of Iniadi (78.4 ppm) for high seed zinc content were the important sources. All accessions of Raa for high seed protein content (>15%) and those of Enele for drought tolerance, were found to be promising sources. Further evaluation of promising sources identified in this study is needed for enhanced utilization of germplasm in pearl millet improvement.
The genebank at the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru, India holds a collection of 542 accessions from the Caribbean and Central American (CCA) regions, of which 424 were evaluated for eight qualitative and 17 quantitative traits at ICRISAT farm. A hierarchical cluster analysis was performed using the scores of the first nine principal components that resulted in four clusters. The accessions of these four clusters exhibited the following good characteristics: cluster 1 had high pod-bearing length and high seed protein content; those of cluster 2 had high degree of branching, large number of pods per plant and high seed yield per plant; those of cluster 3 had long pods; and those of cluster 4 had larger seeds. In the whole collection of accessions, diversity was found to be maximum (H′ = 0.630+0.026) for plant height and minimum for tertiary branches per plant (H′ = 0.259+0.026). The highest correlation coefficient was observed between racemes per plant and pods per plant (r= 0.914) followed by between pods per plant and seed yield per plant (r= 0.744), and between shelling percentage and the harvest index (r= 0.703). In view of the poor representation of the world collection of pigeonpea (13,771 accessions) from the CCA regions, launching of collection missions in these countries has been suggested to fill gaps and increase the variability. Multi-location evaluation of the collections for agronomic traits at potential locations in the CCA regions and systematic evaluation for nutritional traits and resistance to biotic and abiotic stress could result in the identification of useful genotypes, particularly vegetable types, for use in breeding programmes to develop high-yielding cultivars as well as to release as varieties in these regions.