The chitin is extracted from the cuttlebone of S. inermis and the mineral contents are predictable. The structure and degree of deacetylation of extracted cuttlebone chitin is dogged through Fourier Transform Infrared...The chitin is extracted from the cuttlebone of S. inermis and the mineral contents are predictable. The structure and degree of deacetylation of extracted cuttlebone chitin is dogged through Fourier Transform Infrared (FT-IR) spectroscopy. The extracted cuttlebone chitin is used as the substrate for the production of chitinase from Vibrio sp. The extra cellular proteins are concentrated by ammonium sulphate precipitation, dialysed and then purified by using gel (sephadex G-100) chromatography. Among the 40 fractions, only two fractions (active fractions) showed maximum absorbance at 280 nm, which are pooled, dialysed and free-dried. The enzyme activity (0.104 μmoles/ml) and molecular weight (50 - 60 kDa) of purified chitinase is also determined through SDS- PAGE. The optimal condition for chitinase activity is pH between 6.0 - 6.5 and 45℃.展开更多
Ferroelectric lead-free BaTi_(1-x)Zr_(x)O_(3)ceramic powder samples with various compositions(x=0,0.04,0.06)have been synthesized by conventional high-temperature solid-state reaction method at 1450℃for 10 h.Influenc...Ferroelectric lead-free BaTi_(1-x)Zr_(x)O_(3)ceramic powder samples with various compositions(x=0,0.04,0.06)have been synthesized by conventional high-temperature solid-state reaction method at 1450℃for 10 h.Influences of Zr doping on the inter-atomic bonding and charge density distributions inside the lattice structure of BaTiO_(3)were analyzed through powder X-ray diffraction(XRD)and maximum entropy method.Lattice parameter and cell volume values are found to be increasing with the incorporation of Zr content.Calculated average grain sizes are found to be in the range of 23-28 nm.Maximum entropy mapping of electron density analysis reveals the reduction in ionic nature along Ba-O bond and the enhancement of covalent nature along Ti-O bond.Energy band gap values were determined from ultraviolet-visible(UV-Vis)spectra.Surface morphology and microstructures of the samples were analyzed from scanning electron microscopy(SEM)micrographs.Particles with irregular sizes were observed in all the prepared ceramics.Stoichiometry of the samples was further confirmed by energydispersive X-ray spectroscopy(EDAX).展开更多
Doped lanthanum manganites La_(1-x)Ca_(x)MnO_(3) with five different concentrations of Ca(x=0.1,0.2,0.3,0.4 and 0.5) were synthesized by high-temperature solidstate reaction method and characterized.The prepared sampl...Doped lanthanum manganites La_(1-x)Ca_(x)MnO_(3) with five different concentrations of Ca(x=0.1,0.2,0.3,0.4 and 0.5) were synthesized by high-temperature solidstate reaction method and characterized.The prepared samples were experimentally analyzed by X-ray diffraction(XRD),ultraviolet-visible spectroscopy(UV-Vis),scanning electron microscopy/energy dispersive spectroscopy(SEM/EDS) and vibrating sample magnetometer(VSM)measurements.Orthorhombic structure is confirmed for this compound from powder X-ray diffraction data.The XRD data confirm the shrinkage in the unit cell of synthesized samples for increasing calcium concentration.The UV-Visible analysis for the estimation of optical band gap(E_(g)) reveals that the band gap decreases with the incorporation of Ca.The synthesized samples were investigated for charge density distribution using maximum entropy method,utilizing the XRD data sets.From the charge density analysis,it is found that the bond lengths for La-O and Mn-O bonds decrease with the addition of Ca.The ionic nature between La and O atoms and covalent nature between Mn and O atoms are enhanced for 40% of calcium-doping.For 50% of Ca-doped sample,ionic nature between La and O atoms and covalent nature between Mn and O atoms decrease.All the prepared samples exhibit ferromagnetism at 20 K and paramagnetism at 300 K.展开更多
An investigation on the precise electronic structure and bonding interactions has been carried out on Ba1-xSrxZr0.1Ti0.9O3 （short for BSZT, x = 0, 0.05, 0.07 and 0.14） ceramic systems prepared via high-temperature s...An investigation on the precise electronic structure and bonding interactions has been carried out on Ba1-xSrxZr0.1Ti0.9O3 （short for BSZT, x = 0, 0.05, 0.07 and 0.14） ceramic systems prepared via high-temperature solid state reaction technique. The influence of Sr doping on the BSZT structure has been examined by characterizing the prepared samples using PXRD, UV-visible spectrophotometry, SEM and EDS. Powder profile refinement of X-ray data confirms that all the synthesized samples have been crystallized in cubic perovskite structure with single phase. Charge density distribution of the BSZT systems has been completely analyzed by the maximum entropy method （MEM）. Co-substitution of Sr at the Ba site and Zr at the Ti site into the BaTiOz structure presents the ionic nature between Ba and O ions and the covalent nature between Ti and O ions, revealed from MEM calculations. Optical band gap values have been evaluated from UV-visible absorption spectra. Particles with irregular shapes and well defined grain boundaries are clearly visualized from SEM images. The phase purity of the prepared samples is further confirmed by EDS qualitative spectral analysis.展开更多
文摘The chitin is extracted from the cuttlebone of S. inermis and the mineral contents are predictable. The structure and degree of deacetylation of extracted cuttlebone chitin is dogged through Fourier Transform Infrared (FT-IR) spectroscopy. The extracted cuttlebone chitin is used as the substrate for the production of chitinase from Vibrio sp. The extra cellular proteins are concentrated by ammonium sulphate precipitation, dialysed and then purified by using gel (sephadex G-100) chromatography. Among the 40 fractions, only two fractions (active fractions) showed maximum absorbance at 280 nm, which are pooled, dialysed and free-dried. The enzyme activity (0.104 μmoles/ml) and molecular weight (50 - 60 kDa) of purified chitinase is also determined through SDS- PAGE. The optimal condition for chitinase activity is pH between 6.0 - 6.5 and 45℃.
文摘Ferroelectric lead-free BaTi_(1-x)Zr_(x)O_(3)ceramic powder samples with various compositions(x=0,0.04,0.06)have been synthesized by conventional high-temperature solid-state reaction method at 1450℃for 10 h.Influences of Zr doping on the inter-atomic bonding and charge density distributions inside the lattice structure of BaTiO_(3)were analyzed through powder X-ray diffraction(XRD)and maximum entropy method.Lattice parameter and cell volume values are found to be increasing with the incorporation of Zr content.Calculated average grain sizes are found to be in the range of 23-28 nm.Maximum entropy mapping of electron density analysis reveals the reduction in ionic nature along Ba-O bond and the enhancement of covalent nature along Ti-O bond.Energy band gap values were determined from ultraviolet-visible(UV-Vis)spectra.Surface morphology and microstructures of the samples were analyzed from scanning electron microscopy(SEM)micrographs.Particles with irregular sizes were observed in all the prepared ceramics.Stoichiometry of the samples was further confirmed by energydispersive X-ray spectroscopy(EDAX).
文摘Doped lanthanum manganites La_(1-x)Ca_(x)MnO_(3) with five different concentrations of Ca(x=0.1,0.2,0.3,0.4 and 0.5) were synthesized by high-temperature solidstate reaction method and characterized.The prepared samples were experimentally analyzed by X-ray diffraction(XRD),ultraviolet-visible spectroscopy(UV-Vis),scanning electron microscopy/energy dispersive spectroscopy(SEM/EDS) and vibrating sample magnetometer(VSM)measurements.Orthorhombic structure is confirmed for this compound from powder X-ray diffraction data.The XRD data confirm the shrinkage in the unit cell of synthesized samples for increasing calcium concentration.The UV-Visible analysis for the estimation of optical band gap(E_(g)) reveals that the band gap decreases with the incorporation of Ca.The synthesized samples were investigated for charge density distribution using maximum entropy method,utilizing the XRD data sets.From the charge density analysis,it is found that the bond lengths for La-O and Mn-O bonds decrease with the addition of Ca.The ionic nature between La and O atoms and covalent nature between Mn and O atoms are enhanced for 40% of calcium-doping.For 50% of Ca-doped sample,ionic nature between La and O atoms and covalent nature between Mn and O atoms decrease.All the prepared samples exhibit ferromagnetism at 20 K and paramagnetism at 300 K.
文摘An investigation on the precise electronic structure and bonding interactions has been carried out on Ba1-xSrxZr0.1Ti0.9O3 （short for BSZT, x = 0, 0.05, 0.07 and 0.14） ceramic systems prepared via high-temperature solid state reaction technique. The influence of Sr doping on the BSZT structure has been examined by characterizing the prepared samples using PXRD, UV-visible spectrophotometry, SEM and EDS. Powder profile refinement of X-ray data confirms that all the synthesized samples have been crystallized in cubic perovskite structure with single phase. Charge density distribution of the BSZT systems has been completely analyzed by the maximum entropy method （MEM）. Co-substitution of Sr at the Ba site and Zr at the Ti site into the BaTiOz structure presents the ionic nature between Ba and O ions and the covalent nature between Ti and O ions, revealed from MEM calculations. Optical band gap values have been evaluated from UV-visible absorption spectra. Particles with irregular shapes and well defined grain boundaries are clearly visualized from SEM images. The phase purity of the prepared samples is further confirmed by EDS qualitative spectral analysis.
