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Dalawai S.P.,Shivaji University | Shinde T.J.,Smt KRP Kanya Mahavidyalaya | Gadkari A.B.,GKG college | Vasambekar P.N.,Shivaji University
Journal of Solid State Electrochemistry | Year: 2016

Nanocrystalline ferrite powders of NixZn1 − x + yFe2−2ySnyO4 (x = 0, 0.2, 0.4, 0.6, 0.8, 1.0 and y = 0.1, 0.2) were prepared by oxalate co-precipitation method and characterized by XRD, FT-IR and FE-SEM techniques. The ferrite thick films (FTFs) of all compositions were prepared by screen printing technique and tested for gas sensing behaviour for liquid petroleum gas (LPG), ethanol (C2H5OH) and chlorine (Cl2). For LPG, the sensitivity decreases with an increase in Ni2+ up to x = 0.6. It increases slightly for further increment in Ni2+. For this gas, the sensitivity is higher for higher concentration of Sn4+ (y = 0.2) while the optimum temperatures are smaller than that for lower concentration of Sn4+ (y = 0.1). The response and recovery times increase with the increase in Ni2+ for lower concentration of Sn4+ (y = 0.1), while at higher concentration of Sn4+ (y = 0.2), there is increase (for Ni2+ up to x = 0.6) and decrease (for further increase in Ni2+ up to 1.0) in response and recovery times. For ethanol and Cl2, the sensitivity of Zn FTFs decreases with an increase in Ni2+ and increases with an increase in Sn4+. For these gases, the optimum temperature is found to be higher for higher concentration of Sn4+. The response and recovery times of Zn FTFs for ethanol and Cl2 increase with increasing Ni2+ and Sn4+. © 2016, Springer-Verlag Berlin Heidelberg. Source


Dalawai S.P.,Shivaji University | Shinde T.J.,Smt KRP Kanya Mahavidyalaya | Gadkari A.B.,GKG college | Vasambekar P.N.,Shivaji University
Journal of Materials Science: Materials in Electronics | Year: 2015

Nanocrystalline ferrite samples with composition NixZn1−xFe2O4 (x = 0, 0.2, 0.4, 0.6, 0.8, 1.0) were prepared by oxalate co-precipitation method. Thick film of ferrites was prepared by screen printing techniques on glass substrates. The ferrite samples were characterized by X-ray diffraction (XRD), thermo gravimetric and differential thermal analysis (TG–DTA), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy and field emission scanning electron microscopy techniques. The TG–DTA and XRD confirms the formation of ferrite phase and cubic spinel structure. FT-IR spectra show two major absorption bands near 400 and 600 cm−1 corresponding to tetrahedral and octahedral sites respectively. The structural parameters like lattice constant, crystallite size, ionic radii, ionic bond lengths and force constants of ferrite powders were calculated. The grain size of the ferrite thick films was lies in the range 30–65 nm. Gas sensing properties of ZnFe2O4, NiFe2O4 and Ni0.6Zn0.4Fe2O4 thick films was studied for liquid petroleum gas (LPG), ethanol (C2H5OH) and chlorine (Cl2). Zinc ferrite thick film shows high sensitivity (82 %), good response (30 s) and recovery time (90 s) for ethanol as compared to LPG and Cl2. Nickel ferrite thick film shows good sensitivity (63 %), better response (30 s) and recovery time (70 s) for LPG. Ni0.6Zn0.4Fe2O4 is more sensitive for Cl2 followed by ethanol as compare to LPG. Among nickel, zinc and Ni0.6Zn0.4Fe2O4 thick films, zinc ferrite thick film is more sensitive for LPG, C2H5OH and Cl2. © 2015, Springer Science+Business Media New York. Source


Gadkari A.B.,GKG college | Shinde T.J.,Smt KRP Kanya Mahavidyalaya | Vasambekar P.N.,Shivaji University
Advanced Materials Letters | Year: 2013

The Mg0.6 Cd0.4 Fe2O4 ferrite powder was synthesized by oxalate co-precipitation method. The crystal structure and surface morphology were examined by XRD, SEM and FT-IR techniques. The nanocrystallite Mg0.6Cd0.4Fe2O4 sensor was tested for LPG, Cl2 and C2H5OH. The sensitivity was measured at various operating temperatures in the range of 100-400oC. The sensor shows highest sensitivity at operating temperature 225oC for LPG (~ 78%). It shows good sensitivity at operating temperature of 198oC for Cl2 (~75%) and ethanol (~ 65%). The sensor exhibits a lower response and recovery time for LPG and Cl2 as compared to C2H5OH. © 2013 VBRI press. Source


Dalawai S.P.,Shivaji University | Gadkari A.B.,GKG college | Shinde T.J.,Smt KRP Kanya Mahavidyalaya | Vasambekar P.N.,Shivaji University
Advanced Materials Letters | Year: 2013

Cadmium ferrite was prepared by standard ceramic method and characterized by XRD, IR and SEM techniques. The X-ray analysis confirms the formation of single phase cubic spinel structure. The lattice constant decreases slightly and porosity increases with increase in sintering temperature. The crystallite size of the samples lies in the range of 22.83 to 24.44 nm. The IR study shows two absorption bands around 400 cm-1 and 600 cm-1 corresponding to octahedral and tetrahedral sites respectively. The grain size increases and switching field decreases with increases in sintering temperature. © 2013 VBRI press. Source


Kamble R.D.,Tatyasaheb Kore Institute of Engineering and Technology | Jadhav A.R.,Smt KRP Kanya Mahavidyalaya
Asian Pacific Journal of Tropical Biomedicine | Year: 2012

Objective: The aim of this experimental study was production, purification and characterization of alkali stable xylanase from locally isolated Cellulosimicrobium sp. MTCC 10645, which is an important industrial enzyme used in the pulp and paper industry. Methods: The enzyme was produced in Erlenmeyer flasks containing fresh basal salt medium supplemented with 1% oat spelt xylan. The enzyme was extracted and isolated using ammonium sulphate precipitation and dialysis. It was further purified using DEAE cellulose chromatography and purity was checked by SDS-PAGE. Effect of temperature and pH on activity and stability of enzyme was studied. The enzyme was laso studied for its substrate specificity and kinetic parameters. Results: The isolate was identified on the basis of cultural, morphological, physiological and biochemical properties as well as 16S rRNA sequencing. Among the carbon sources tested, birchwood xylan found prominent for increased level of xylanase i. e. 96.33 U/ml. The enzyme was purified by DEAE cellulose chromatography at NaCl concentration of 0.25 M and had a molecular mass of 78.0 kDa. Xylanase was purified sixteen fold with a specific activity of 246.6 U/mg. Xylanase activity was maximum at 50°C. The enzyme was thermostable retaining 8% of the original activity after incubation at 60°C of 4 h. The enzyme was active over a pH range of 6.0-11.0, although its activity was optimal at pH 7.0. About 48.52% of the enzyme activity was retained after 4 h at pH 11.0. The enzyme was active on oat spelt and birchwood xylans but not on avicel, CMC, cellobiose, starch or p-nitrophenyl xylopyranoside. The xylanase had Km and Vmax values of 4.76 mg/ml and 232.5 μmol/min/mg, respectively when birchwood xylan used as substrate. Conclusions: The xylanase showed a unique pattern of xylan hydrolysis releasing a large amount of intermediate products (xylotriose and xylobiose) with small quantity of xylose. Some of these characteristics make this enzyme potentially effective in xylan biodegradation and pulp bleaching. © 2012 Asian Pacific Tropical Biomedical Magazine. Source

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