[en] An attempt was made to prepare nano-size barium hexa-ferrite particles following a hydrothermal precipitation-calcination route using barium and iron nitrate solutions. During hydrothermal treatment at 180 deg. C (2 h precipitation time) barium carbonate and hematite phases were formed. This precursor was calcined at 800, 1000 and 1200 deg. C to determine the conditions for obtaining barium hexa-ferrite. The characterization studies on calcined products revealed that up to 800 deg. C, the major crystalline phases (barium carbonate and hematite) of the precursor were retained. At 1000 deg. C, formation of barium hexa-ferrite started and at 1200 deg. C, though most of the major peaks of X-ray diffractogram corresponded to barium hexa-ferrite, a number of peaks corresponding to hematite were also present. Some low intensity peaks for barium carbonate were observed. The average particle size was 40 nm. Saturation magnetization, remanence magnetization and coercivity were found to be 40.0, 21.6 emu g^-1 and 2.87 kOe, respectively. The values obtained both for coercivity and magnetization for the present sample were lower than the reported bulk values which could be due to the fact that the sample prepared through the present technique was not mono-phasic

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No abstract available

[en] Nanophase Ni_1-xZn_xFe₂O₄ (x=0, 0.5, 1.0) samples were prepared by chemically precipitating hydroxides followed by hydrothermal processing. The products were characterized by X-ray diffraction and Moessbauer spectroscopy. Ferrite formation was found to be quite sensitive to the procedures adopted for preparing the hydroxide slurry prior to hydrothermal treatment. Nickel ferrite could be prepared in pure phase by co-precipitation as well as by mixing separately precipitated hydroxides. However, Ni_0.5Zn_0.5Fe₂O₄ could only be prepared by co-precipitation. Leaving small amount of sodium in the slurry seems to obstruct pure phase formation of Ni_0.5Zn_0.5Fe₂O₄ and results in partial formation of α-Fe₂O₃. A similar effect is observed in zinc ferrite

[en] Uptake of testosterone-7-³H and estradiol-17β-6,7-³H by various tissues and the effect of testosterone and estradiol-17β on the spermatozoa and accessory genital organs of castrated male rats were studied. The results indicated that there were differences in response of the epididymis and vas deferens to androgen and estrogen. (M.G.B.)

[en] Drug delivery system (DDS)promises to solve a number of issues associated with conventional therapeutic agents, including their poor bioavailability, lack of targeting capability, nonspecific distribution, systemic toxicity and low therapeutic index. Naturally occurring bio-molecules such as proteins are an attractive alternative to synthetic polymers which are commonly used in fabrication of DDS because of their biocompatibility and biodegradability. Moreover, due to the presence of reactive groups protein-based nanoparticles can be surface functionalised with the target specific ligands.Common methods available for the preparation of protein nanoparticles are desolvation, emulsification, high pressure homogenization, etc. Major disadvantages with these methods are use of organic solvent and removal of organic oil from the nanoparticle solution. Further, the most common stabilizing agent used in previous studies is glutaraldehyde which can cause toxicity. Therefore, there is a need to develop greener methods that can overcome toxicity associated with excipients. The proposed thesis is thus aimed to develop physical and chemical methods of preparing nano-carrier from protein sources namely albumin and gelatin and to evaluate them as DDS. Well established anti-inflammatory/anticancer drugs such as Curcumin, Doxorubicin (Dox) and Irinotecan (IRI) were chosen as payload to study the role of physico-chemical properties like surface modification, size and hydrophobicity of protein nanoparticles in controlling the release and pharmacokinetic behavior of the entrapped drug. Finally, attempts were also made to evaluate the optimized nano formulations of curcumin, Dox and IRI for various therapeutic applications using murine models. The presentation will give brief overview of results pertaining to thesis objectives

[en] Gold nanoparticles are well established radio sensitizer of cancer cells. However the effect of the surface property mainly the shape of gold nanoparticles on its radio sensitizing activity is not studied in detail. Here in present study, our objective was to address this issue. For this, gold nanoparticles (AuNPs) of varying shape and size were synthesized by simply adjusting the pH of the solution of gelatin and gold salt. The characterisation revealed the pH induced size selected synthesis of spherical, triangular and star shaped gold nanoparticles. The effect of shape on the radiosensitizing ability of gold nanoparticle is under evaluation. (author)

[en] In our previous study we attempted to see the effect of cerium doping (Ce/Fe ratio 0.015 to 0.074) on goethite matrix and conversion of doped goethite to hematite. In the present communication, nano-structured α-Fe₂O₃-CeO₂ composite with Fe/Ce weight ratio as 1.1 has been synthesized by calcination of goethite-cerium hydroxide precursor prepared by co-precipitation method. It was observed that co-precipitation of cerium along with iron in hydroxide medium resulted in hindering the formation of crystalline order as the precursor formed showed poorly crystallized goethite and almost no crystallinity in Ce(OH)₄. Calcination of the precursor at 400 deg. C showed the formation of hematite together with a broad peak corresponding to cerium oxide whereas at 800 deg. C, two distinct phases of α-Fe₂O₃ and CeO₂ were observed. The Moessbauer spectra showed the presence of a paramagnetic component both for the precursor as well as for the sample calcined at 400 deg. C but on raising the calcination temperature to 800 deg. C, the paramagnetic component disappeared and the spectrum corresponding to pure α-Fe₂O₃ phase was observed. The microstructure of the product obtained by calcining at 800 deg. C showed rod like structure (30 to 50 nm width and 300 to 500 nm length) of α-Fe₂O₃ having equi-dimensional CeO₂ particles on and around the surface. Besides the rods, equi-dimensional particles and agglomerates corresponding to CeO₂ were also observed. The results show that co-precipitation followed by calcinations gives nanorods hematite with CeO₂ particles bonded to its surface

[en] Cerium-doped goethite (α-FeOOH) samples were prepared by aqueous precipitation route. During doping Ce(IV)/Fe(III) atomic ratio was varied in the range of ∼0.014 to ∼0.07. The characterization by XRD showed that irrespective of the amount of cerium doping, all the sample were well crystallized showing only goethite as the crystalline phase. The cell parameter a of goethite marginally decreased while b and c marginally increased as the Ce(IV)/Fe(III) atomic ratio increased till 0.035:1 and further increase in this ratio showed much more increase in b and c cell parameters. The lattice image of a typical sample with Ce(IV)/Fe(III) 0.035:1, indicated (1 1 0) plane of goethite lattice and no plane growth corresponding to any phase of cerium. On heating the samples to 673 K, it was observed that goethite is completely transformed to nano-sized α-Fe₂O₃ while the formation of cerium oxide was only partial. Further calcination to 1073 K showed the formation of two distinct phases of CeO₂ and α-Fe₂O₃. Lattice image of the same sample revealed that crystal growth of CeO₂ occurs along (1 1 1) plane. CeO₂ crystallites did not separate from α-Fe₂O₃. Nano-structures of CeO₂-α-Fe₂O₃ were retained even after calcination at 1073 K

[en] Vibrating sample magnetometer (VSM) and Moessbauer spectroscopy are used to characterize the magnetic behaviour of fine magnetite particles obtained from (i) pure goethite and (ii) Ni-doped goethite, in ammoniacal solution. The latter sample has 0.4 wt% Ni which has significantly changed the properties of the sample. The Ni-doped magnetite shows a much higher overoccupancy of tetrahedral sites by iron atoms as compared to the undoped sample. TEM study shows that presence of Ni ions leads to narrower size distribution of magnetite particles as compared to the magnetite obtained from undoped goethite. The coercive field is also affected by presence of Ni, being only 105 Oe for the Ni-doped magnetite as against 170 Oe in the undoped sample