We report investigations on polycrystalline LaCo1?xAlxO3 (x = 0–0.9) bulk samples. The solid state synthesized samples showed a coexistence of rhombohedral and monoclinic phases in the intermediate concentrations (0.2 ≤ x ≤ 0.5) and pure rhombohedral phase otherwise. The observed effect of Al doping on dc transport has been analysed on the basis of small polaron hopping mechanism. The magnetisation results presented give evidence of weak ferromagnetism and anomalous temperature dependence of coercivity which we associate to the canting of the localised high-spin Co(III) and anti-symmetric exchange interactions at low temperatures. 相似文献
Pr( Ⅲ ) and Nd( Ⅲ ) can be utilized as absorption spectroscopic probes to investigate the interaction of biomolecules like Lysozyme (HEW) with Ca( Ⅱ ) in-vitro ; the most abundant metal ion in the human body system. The spectroscopic techniques involving comparative absorption, absorption difference, and quantitative intensity analysis using 4f-4f transitions are utilized for changes in the inner sphere coordination pattern of Pr( Ⅲ ) and Nd(Ⅲ ) in solution as well as in solid state. The present study deals with an important biomolecule in human metabolism, that is, Lysozyme (HEW). The absorption er-Condon the probab spectral parameters such as the oscillator strength (P), the Judd-Ofelt (Tλ) intensity parameters, and the Slatinter electronic parameters are calculated using chi square methods. The obtained results are used to determine le geometry of the complex in the solution, the nature of the bond between Pr(Ⅲ)/Nd(Ⅲ) with lysozyme, and the inner sphere coordination environment of f-f transitions. The results obtained from various experimental conditions are utilized to investigate the coordination changes in the Pr(Ⅲ)/Nd(Ⅲ) complexes caused by different coordinating sites of lysozyme, normalized bite, denticity, the solvent nature, the coordination number, the nature of bond and other parameters to mimic the interaction of the Ca( Ⅱ ) ion with such biomolecule. 相似文献
Natural hazards such as flooding can cause changes in land-cover. The present study deals with the changes in land-cover in
three worst affected districts (Anand, Vadodara and Kheda) of Gujarat state in India due to severe flood during 2005. The
Indian Remote Sensing (IRS) P6 Linear Imaging Self Scanning (LISS) III satellite imageries of pre- and post-flooding periods
were used as sources of information for the study area. Three classification approaches (unsupervised ISODATA, supervised
Maximum Likelihood Classifier, and fuzzy rule based) were used to extract flood induced land-cover information. Results obtained
from the above classification approaches were compared. Soft computing technique such as fuzzy based image classification
gave better separability amongst classes as compared to hard classification techniques. The accuracy assessment showed that
the fuzzy approach can predict land-cover more accurately than traditional approach and also showed great potential for dealing
with mapping of flood induced land-cover. Unsupervised classification results for the period October 2004 to October 2005
revealed decrease in inland water bodies (14.49%) and agricultural area (6.42%) while increase in remaining land-cover. During
February 2005 to February 2006, all land-cover classes decreased except agricultural fallow and sparse vegetation. In case
of supervised classification, decreasing trend was observed only in case of agricultural area (6.78%) during October 2004
to October 2005. Similarly, during February 2005 to February 2006, increase in coastal water bodies (0.73%) and sparse vegetation
(1.7%) was observed where as decreasing trend was noticed in the remaining land-cover classes. In fuzzy based classification,
only decrease in agricultural area (7.09%) was observed from October 2004 to October 2005, whereas during February 2005 to
February 2006, decrease in area was exhibited in all land-cover classes except coastal water bodies and sparse vegetation.
Change detection indicated interchange of areas between inland and coastal water bodies and decrease in agricultural area
leading to increase in area of agricultural fallow and sparse vegetation. 相似文献
Delineation of groundwater potential zones (GWPZ) has been performed for a coastal groundwater basin of eastern India. The groundwater potential zone index (GWPZI) map is generated by using Analytic Hierarchy Process (AHP) from different influencing features, e.g., Land Use/Land Cover (LU/LC), soil (S), geomorphology (GM), hydrogeology (HG), surface geology (SG), recharge rate (RR), drainage density (DD), rainfall (RF), slope (Sl), surface water bodies (SW), lineament density (LD), and Normalized Difference Vegetative Index (NDVI). Recharge rate values are estimated from hydrological water balance model. Overlay weighted sum method is used to integrate all thematic feature maps to generate GWPZ map of the study area. Four zones have been identified for the coastal groundwater basin [very good: 36.39 % (273.53 km2, good: 43.57 % (327.47 km2), moderate: 18.27 % (137.30 km2), and poor: 1.77 % (13.27 km2)]. Areas in north to south-west and south-east direction show very good GWPZ due to the presence of low drainage density. GWPZ map and well yield values show good agreement. Sensitivity analysis reveals that exclusion/absence of rainfall and lineament density increases the poor groundwater potential zones. Omission of hydrogeology, soils, surface geology, and NDVI show maximum increase in good GWPZ. Obtained GWPZ map can be utilized effectively for planning of sustainable agriculture. This analysis demonstrates the potential applicability of the methodology for a general coastal groundwater basin. 相似文献
It has been observed that, compared to bulk form, the nanocrystalline α-Fe2O3 is finding application in various areas. Magnetic properties of α-Fe2O3 are found to be influenced by the size of particles and are also sensitive to synthesis method employed for sample preparation. In the present work we have prepared a series of Nd doped α-Fe2−xO3 samples (x = 0.0–0.5) by combustion method, without using any fuel. The analysis of room temperature neutron diffraction patterns shows that all the compounds of the series form in the hematite (α-Fe2O3) structure, space group R−3c. Magnetization measurements show that there is a broad distribution of particle size in the samples. We find that the increase in the Nd content results in the dilution of magnetism of α-Fe2O3. From results we believe that inclusion of Nd in α-Fe2O3 drastically modifies the magnetic properties. 相似文献
This paper analyzes the influence of electric poling on structure, magnetism, and ferroelectricity by temperature-dependent Raman scattering (180 K–500 K), magnetic susceptibility, and ferroelectric measurements on Pb0.9Bi0.1Fe0.55Nb0.45O3 (PBFNO) multiferroic. X-ray diffraction (XRD) has confirmed the monoclinic structure for PBFNO sample before and after poling. Rietveld refined XRD for poled and unpoled sample shows the influence of electric poling on Fe-O1, Fe-O2, Nb–O, and Bi-O modes with small variation in the lattice parameters. The unpoled PBFNO exhibits broad and overlapping 10 active modes at room temperature (100 to 1300 cm?1) at 147, 212, 255, 431, 479, 561, 700, 795, 835, and 1112 cm?1. In case of a poled sample, Pb–O and Nb–O-Nb modes become more active compared to the unpoled sample. Changes observed in the temperature-dependent magnetic measurements, i.e., ZFC/FC and M-H loop, evidence the poling effects on Fe–O and Nb–O active modes. By poling the improvement in ferroelectric domain, ordering occurs, and it is confirmed by P-E loops. The consequences of numerous investigations on electric poling of PBFNO will provide the foundation for future device development and design.
Magnetic and dielectric properties of the double perovskite compounds of the type R2CuTiO6 (RCTO, where R=Y, La, Pr and Nd) has been studied. Y2CuTiO6 (YCTO) crystallizes in a hexagonal unit cell, whereas the other three compounds form into orthorhombic structure. All four
compounds show paramagnetic behavior down to 5 K. The dielectric studies show moderate dielectric constant (ε′) and very small dielectric loss (tan δ) for YCTO. The orthorhombic members of RCTO compounds exhibit moderate values of ε′ and tan δ. The dielectric properties are presented and discussed here in the light of the influence of structure and rare-earth ions
on the physical properties of RCTO compounds. 相似文献
The canal water supply, which is the only source of irrigation, in the rice-dominated cropping system of the Hirakud canal command (eastern India) is able to meet only 54 % of the irrigation demand at 90 % probability of exceedance. Hence, considering groundwater as the supplemental source of irrigation, conjunctive use management study by combined simulation-optimization modelling was undertaken in order to predict the maximum permissible groundwater pumpage from the command area. Further, optimal land and water resources allocation model was developed to determine the optimal cropping pattern for maximizing net annual return. The modelling results suggested that 2.0 and 2.3 million m3 of groundwater can be pumped from the bottom aquifer during monsoon and non-monsoon seasons, respectively, at 90 % probability of exceedance of rainfall and canal water availability (PERC). Optimal cropping patterns and pumping strategies can lead to about 51.3–12.5 % increase in net annual return from the area at 10–90 % PERC. The sensitivity analysis of the model indicates that the variation in the market price of crops has very high influence on the optimal solution followed by the cost of cultivation and cultivable area. Finally, different future scenarios of land and water use were formulated for the command area. The adoption of optimal cropping patterns and optimal pumping strategies is strongly recommended for sustainable management of available land and water resources of the canal command under hydrological uncertainties. 相似文献
Journal of Superconductivity and Novel Magnetism - Magnetic phase coexistence in the substituted perovskite compound, La0.4Bi0.3Sr0.3MnO3, is attributed to the spontaneous moment and a step-like... 相似文献