Magnetoresistive properties of Gd doped various polycrystalline samples of Ruddlesden -Popper series (La1-xSrx)n+1MnnO3n+1 (n = 2) sintered at temperature 11000C for 24 hours in air have been investigated from room temperature down to liquid nitrogen temperature using standard four-probe technique. X-ray diffraction pattern have confirmed the single phase structure of all the samples with no significant trace of impurity. Sample La1.4Sr1.6Mn2O7 shows a Metal-Insulator (M-I) transition with a peak in the electrical resistivity at temperature Tp ~ 134K and 117 K with an applied magnetic field of 0.86 and O Tesla, respectively. Replacement of La by small amount of Gd atoms in this compound is found to lower the ferromagnetic (or metal-insulator) transition temperature, an effect which would be due to bond bending caused by the lattice adjusting to the size differential between the La and Gd ions. On the contrary, normalized resistivity behavior as a function of temperature for samples La1.0Gd0.4 Sr1.6Mn2O7, La1.0Gd0.6Sr1.4Mn2O7, and La1.0Gd0.8Sr1.2Mn2O7 in zero field and in an applied magnetic field of 0.86 T reveal that when non-magnetic Sr is replaced with magnetic Gd atom the transition temperature increases dramatically favoring metallic phase. The magnetic property of Gd atom might be responsible for higher transition temperature. Increase in magnetoresistance at lower field is observed to be faster than at higher field. For example, sample of La1.4Sr1.6 Mn2O7 exhibited 15% magnetoresistance (MR) at an applied magnetic field of 0.13 T whereas the MR of 19% has been obtained for this sample upon the application of 0.86 T magnetic field. All the other compounds exhibited similar behavior. The exhibited large MR effects in this compound at low temperature and very low field might be associated with magnetic-domain based scattering or spin-polarized tunneling between grains.
Agricultural byproducts like Carrot skin, Banana husk, Pomegranate husk, Radish skin and Papaya skin were used in their natural state on which the study of adsorption of toxic metal ions Pb(II), Cd(II), Cu(II) and Hg(II) at 25°C has been made. The values of Frundlich constants (n and k) are estimated from the study. It can be seen that, adsorption increases with respect to increase in concentration of metal ions.
Isonicotinic acid hydrazide (INH) when condensed with carbon disulphide in ethanolic potassium hydroxide yielded potassium dithiocarbazinate (2). On heating (2) and acid hydrazide yielded compounds (3 a-I). The compounds (3a-1) were reacted with 2,3- dichloroquinoxaline and yielded compounds (4a-I). The antifungal and antibacterial activity of the compounds have also been evaluated. The structures of the new compounds were established on the basis of analytical and spectral data.
The spatial and temporal distribution of organic carbon content in a surface sediment were analysed in the Pahang mangrove forest. Three transects in Kuantan mangrove, two transects in Bebar mangrove and one transect in Miang mangrove were established extending from the high intertidal site within the mangrove forest to low intertidal in front of the mangrove forest. Analysis of transects in mangrove sediments indicated that the amount of fine material and organic carbon content increases towards near the front mangrove. The highest organic carbon content occurred in fine grained sediments of the Miang (3.94 ± 0.19%) and Bebar (3.67 ± 0.28%) compared to Kuantan (2.17 ± 0.12%) mangrove areas. However in this study, there is no significant (P > 0.05) relationship between the organic carbon content within the sampling station and the seasonal changes.
The objective of this investigation was to develop a simple thin layer chromatographic method for the determination of Cephalexin and Cefaclor, Cephalosporins widely used in clinical practice. Thin Layer Chromatography of selected Cephalosporins was performed on precoated silica gel plates with concentrating zone (20x20 cm) by development in different mobile phase.
Quantitative evaluation was performed by measuring the absorbance reflectance of the analyte spots at lambda=245 nm and by the detecting reagents. This method is rapid, selective, precise and accurate and thus can be used for the routine analysis of Pharmaceuticals formulations in quality control laboratories of the Pharmaceutical Industry.
Water is the mirror of civilization since the origin of life. The increase in population coupled with unplanned urbanization and industrialization has resulted in damage and deterioration in ground water quality. Ground water is the most important source of water supply for irrigation, industries and for drinking purposes. Municipal and industrial sewage water when enters into an aquifer are the major sources of organic and inorganic pollutants. Trace elements in ground water within the limits may be useful but harmful when the value increases beyond the limits. Hence, the aim of present study is to assess the heavy metals seasonally concentration in the year 2003-04 by Atomic Absorption Spectrophotometer (AAS). Total iron, Cu, Mn, Zn, Ni & Cr are analyzed and these trace elements has ranged. Cu has the range of 0.010 - 0.064, 0.01 1 - 0.040 and 0.005 - 0.068 ppm range of 0.010 - 0.061, 0.01 I - 0.040 and 0.005 - 0.06 S ppm in winter, summer and Monsoon Season respectively. Mn ranged from 0.030 -0.740, 0.023 - 0.31 5 and 0.020 - 0.700 ppm in W, S and M respectively, Zn element ranged I-1,0111 0.1 10 -0.910 ppm while Ni and Cr are in the range of 0.010 - 0.016 ppm and BDL in the present study.
Mixed ligand complexes of Ru (III) and Ir (III) with 2-carboxaldehyde pyrrolyl - pyrazine carboxylic hydrazone (cppch)/ 2-acetyl pyridyl-pyrazine carboxylic hydrazone (apph) as primary and thiosalicylic acid (TSA) / 2-amino thiophenol (atp) as secondary ligand have been synthesised and characterised on the basis of analytical, conductance, magnetic and spectral studies., Analytical data suggested l:l:l (M-L/L'-L"H/L"'H) stoichiometry of the complexes [Where M=Ru(III), Ir (III), L = cppch, L' - apph, L"H = TSA and L" 'H - atp]. The molar conductance data (4.2 -6.8 Ohm-1 cm2 mol -1) of the complexes show their non-electrolytic nature. Reflectance spectra suggested octahedral geometry of the complexes. Ir spectra revealed the bidentate nature of the ligands.
Complexes of cobalt (II) and nickel (II) with nimesulide have been synthesised and characterised by elemental analysis, IR, 1H NMR, TGA, magnetic susceptibility and molar conductivity measurements. These studies revealed that they are having octahedral geometry of the type [ML(H2O)2X2] where M=Co(II) and Ni(II); L=C13H12N2SO5; X = Cl, NO3, CH3COO and 1/2SO4. The invitro antifungal studies revealed that the nimesulide complexes are potent against a few tested fungi.
Hydrolysis of Phosphoric p-MeOptienylamide has been kinetically pursued in 0.01-7.0M, HCl media at 40°C (± 0.5). The Zwitterion (or the modified - Neutral) form functions at low acid (0.01 - 0.5M, HCl) molarities while the Neutral form makes an almost constant contribution between 1.0 to 4.0M, HCl. The Monoprotonated species, however, operates in the entire acid range (0.01 - 7.0M, HCl). Neutral electrolyte effect study also favours specific acid catalysis with a +ve ionic strength effect. Arrhenius Parameters’ determination, D2O effect and various correlations strengthen a bimolecular mode of hydrolysis in the entire acid region, leading to 3 mechanic routes in all.
This paper deals the alteration in physico-chemical parameters of river Gomti due to continous daily addition of raw municipal sewage and effluents from Lucknow City. pH., B.O.D., C.O.D, heavy metals including toxic chemical like fluoride and chloride were periodically tested at different sampling stations from June 2004 to Dec. 2004. Most of the parameters have gone high whereas D.O. has decreased significantly. Samples were highly contaminated which has gradually increased from upward to down ward stream (i.e. west to east part of the river). The altered conditions are hazardous for the survival of aquatic life and human health.