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Synthesis and Characterization of C-TiO_2/FeTiO_3 and CQD/C-TiO_2/FeTiO_3 Photocatalysts with Enhanced Photocatalytic Activities Under Sunlight Irradiation

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Acta Metallurgica Sinica(English Letters) 2016年第1期29卷 17-27页

作者： Ramakrishna Dadigala Bhagavanth Reddy Gangapuram Rajkumar Bandi Ayodhya Dasari Veerabhadram Guttena Department of Chemistry Osmania University

Sunlight-driven C-TiO2/FeTiO3 composites were synthesized with different weight fractions of FeTiO3. The as-prepared samples were characterized by UV-Visible diffuse reflectance spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction analysis, transmission electron microscopy, scanning electron microscopy, energy-dis- persive X-ray spectroscopy, and photoluminescence. Under sunlight irradiation, the C-TiO2/FeTiO3 photocatalysts degraded methyl orange （MO） efficiently and displayed much higher photocatalytic activity than that of pure FeTiO3 or carbon-doped titanium dioxide （C-TiO2）, and the C-TiOE/FeTiO3 photocatalyst with 10 wt% of FeTiO3 exhibited the highest photocatalytic activity. The enhancement of photocatalytic activity was mainly ascribed to the formation of a heterojunction between C-TiO2 and FeTiO3, which facilitated the transfer and separation of photogenerated electron-hole pairs. The quenching effects of different scavengers demonstrated that the reactive superoxide radicals （02-） and hydroxyl radicals （OH） played a major role in the MO degradation. The possible photocatalytic mechanism is discussed on the basis of the band structures of C-TiO2 and FeTiO3. To further enhance the photocatalytic efficiency, double-heterojunctioned CQD/C-TiO2/FeTiO3 composite was prepared by loading carbon quantum dots onto the C-TiO2/FeTiO3 surface.

关键词： C-TiO2 FeTiO3 CQD Composites Sunlight photocatalytic activity

Metathesis synthesis, characterization, spectral and photoactivity studies of Ln_(2/3)MoO_4(Ln=La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Er and Y)

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Journal of Rare Earths 2015年第8期33卷 837-845页

作者： Radha Velchuri Suresh Palla G.Ravi Naveen Kumar Veldurthi J.R.Reddy M.Vithal Department of Chemistry Osmania University

Rare earth ortho-oxomolybdates of composition Ln2/aMoO4 （Ln=La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Er and Y） were prepared by metathesis reaction. All these materials were characterized by powder X-ray diffraction, Fourier transform-infrared spectroscopy （FT-IR） and UV-Vis diffuse reflectance spectra. The Rietveld analysis of all the samples was carried out to obtain the unit cell parameters and reliability factors. All the materials were crystallized in tetragonal lattice with I41/a space group. The infrared spectra of all the samples were characterized by bands due to MoO42 units. The bandgap energies of all the samples were obtained from UV-Vis DRS spectra. The luminescence spectra of Ln2/3MoO4 （Ln=Pr, Eu and Dy） showed characteristic transitions of the rare earth ions. The visible light photocatalytic activity of all the samples was studied against degradation of methylene blue.

关键词： metathesis X-ray diffxaction IR spectroscopy UV-Vis spectroscopy photodegradation rare earths

Photometric study of W UMa type binaries in the old open cluster Berkeley 39

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Research in Astronomy and Astrophysics 2009年第10期9卷 1149-1154页

作者： Kandulapati Sriram Yellapragada Ravi Kiron Pasagada Vivekananda Rao Department of Astronomy Osmania University

The study of W UMa binary systems gives a wealth of information about their nature as well as their parent bodies （if any）, like clusters. In this paper, we present the I passband photometric solutions of four W UMa binaries in the open cluster Berkeley 39 using the latest version of the W-D program. The result shows that two binary systems are W-subtype W UMa binary systems and the other two systems are H-subtype W UMa binary systems. No third body has been found in any of the four systems. We found a correlation between the period and mass-ratio as well as temperature and mass-ratio for the respective variables, which is similar to the relationship between mass ratio and total mass of the contact binaries as shown by van＇t Veer and Li et al.

关键词： binaries eclipsing -- binaries close

Photometric study of W UMa type binaries in the intermediate open cluster NGC 7789

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Research in Astronomy and Astrophysics 2010年第2期10卷 159-165页

作者： Kandulapati Sriram Pasagada Vivekananda Rao Department of Astronomy Osmania University

The light curve solutions of two W UMa binary systems in the intermediate open cluster NGC 7789 are presented in this paper. These variables were observed using the 2 m telescope of the IUCAA-Girawali Observatory. The V passband photo- metric solutions of the two W UMa binaries were obtained using the latest version of the W-D program. The result shows that both systems are H-subtype W UMa binaries with high mass ratios.

关键词： binaries: eclipsing- binaries: close

Degradation of Methylene Blue and Rhodamine B Using a New Visible Light-Responsive Photocatalyst, KSb_2PO_(8-x)N_y

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Acta Metallurgica Sinica(English Letters) 2016年第4期29卷 335-343页

作者： G.Ravi CH.Sudhakar Reddy K.Sreenu Ravinder Guje Radha Velchuri M.Vithal Department of Chemistry University College of ScienceOsmania University

Potassium phosphatoantimonates, KSb2PO8 （KSbPO） and KSb2PO8-xNy （KSbPON）, are prepared by solidstate method. Urea is employed as a source of nitrogen for N-doping. Structural, morphological and optical properties of both KSbPO and KSbPON are characterized by powder X-ray diffraction （PXRD）, scanning electron microscopy, energydispersive spectroscopy, Fourier transform infrared spectroscopy and UV-visible diffuse reflectance spectroscopy. Both samples are found to crystallize in a monoclinic lattice with Cc space group. The d-lines of KSbPO and KSbPON are refined by least square fitting the PXRD data, using POWD software to obtain their unit cell parameters. The bandgap energy （Eg） of both pristine and N-doped KSbPO is found from their Kubelka-Munk plot. The KSbPON/visible photocatalytic degradation of methylene blue and rhodamine B has been investigated in aqueous heterogeneous suspension. The generation of .OH in the presence of KSbPON during the photoreaction is verified by a fluorescence technique using terephthalic acid （TA） as a probe.

关键词： Potassium phosphatoantimonates Characterization Organic dyes Photodegradation

Synthesis, Characterization and Antimicrobial Activity of Oxovanadium（IV） Complexes of Schiff Base Hydrazones Containing Quinoxaline Moiety

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Chinese Journal of Chemistry 2012年第4期30卷 935-940页

作者： Lakshmi, P. V. Anantha Satyanarayana, T. Reddy, P. Saritha Department of Chemistry University College for Women Osmania University HyderabadIndia OUPG College Osmania University Mirzapur India

The oxovanadium（IV） complexes of the Schiff base hydrazones, synthesized from 3-hydrazinoquinoxaline-2- one （HQO） with salicylaldehyde （HSHQO）, o-hydroxyacetophenone （HHAHQO）, dehydroacetic acid （HDHAHQO） and o-nitrobenzaldehyde （NBHQO） were synthesized and characterized on the basis of analytical, conductance, magnetic moment, infrared, NMR, ESR and electronic spectral data. The ligands HSHQO, HDHAHQO behaved as monobasic tridentate ONN donors through phenolic oxygen, azomethine nitrogens. The ligand HAHQO acted as a monobasic bidentate ON donor through the phenolic oxygen, azomethine （free） nitrogen and the ligand NBHQO acted as neutral bidentate ON donor through oxygen of the nitro group and azomethine （free） nitrogen.

关键词： oxovanadium(IV) hydrazones ONN donor ON donor

Soret and Dufour effects on unsteady MHD flow past an infinite vertical porous plate with thermal radiation

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Applied Mathematics and Mechanics(English Edition) 2010年第12期31卷 1481-1496页

作者： S.R.VEMPATI A.B.LAXMI-NARAYANA-GARI Department of Mathematics University College of ScienceOsmania University

The objective of the present study is to investigate the effect of flow parameters on the free convection and mass transfer of an unsteady magnetohydrodynamic flow of an electrically conducting, viscous, and incompressible fluid past an infinite vertical porous plate under oscillatory suction velocity and thermal radiation. The Dufour （diffusion thermo） and Soret （thermal diffusion） effects are taken into account. The problem is solved numerically using the finite element method for the velocity, the temperature, and the concentration field. The expression for the skin friction, the rate of heat and mass transfer is obtained. The results are presented numerically through graphs and tables for the externally cooled plate （Gr 〉 0） and the externally heated plate （Gr 〈 0） to observe the effects of various parameters encountered in the equations.

关键词： mass transfer magnetohydrodynamic flow vertical plate suction velocity,Soret and Dufour number thermal radiation finite element method

Optical and X-Ray Studies of Marginal Contact Binary RW Dor Using TESS and XMM-Newton Observatories

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Research in Astronomy and Astrophysics 2023年第11期23卷 183-197页

作者： K.Sriram G.Mamatha Rani Department of Astronomy Osmania University 500007India

Marginal short-period contact binaries are important to understand as they pose a different physical scenario than the predicted theoretical model based on the thermal relaxation oscillation mechanism due to their shallow degree of *** we present the optical and X-ray studies of a contact binary source RW Dor using the Transiting Exoplanet Survey Satellite(TESS)and XMM-Newton *** the first time we report the varying O'Connell effect and explain the asymmetry with a spot *** on the new times of minima,we make a robust estimate of the orbital period of the third body at 47.01~0.52 yr with an eccentricity e=*** show that the period-decreasing trend observed in O-C variation can be explained by both conservative mass transfer from primary to secondary and AML via stellar *** X-ray luminosity exhibited by RW Dor did not vary significantly on three different occasions and was found to be about 3.34×10~(29)erg s~(-1).Assuming that the quiescent X-ray emission is emitted from an undisturbed loop structure,the loop size is estimated to be 0.6-1×10~(10)cm which is≤Alfvén radius r_A~8×10~(10)cm.

关键词： (stars:)binaries(including multiple):close X-rays:binaries stars:activity

Evidence of a Third Body and Photometric Solutions of a High Temperature Marginal Contact Binary CW Aqr

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Research in Astronomy and Astrophysics 2023年第5期23卷 91-100页

作者： A.Vijaya K.Sriram Department of Astronomy Osmania University 500007India

Marginal contact binary systems are an important class of binary systems in exploited by astronomers to understand various astrophysical phenomena as they bridge both semi-detached and overcontact *** studied the photometric data of CW Aqr using the JCB 1.3 m telescope(JCBT),Kepler,and TESS to understand the period variations and constrain the light curve *** noted that the period of CW Aqr is increasing with a mass transfer rate of m=7.53×10^(-8)M_(⊙)yr^(-1)from the secondary to the primary *** also ascertained cyclic deviations along with a parabolic trend in the O-C *** residuals displayed a sinusoidal trend which was fitted with an LTTE,indicating the presence of a third body with an orbital period of P_(3)~10 yr and e=*** fitted the JCBT,Kepler,and TESS photometric normalized light curves and noted the mass ratio to be q~0.32 for both contact and semi-detached *** identified a temperature difference between the primary and secondary components of~2500 *** activity signatures were found in the observed light curves which were also evident from the Hαline studies where the filled-in effect was not *** our study suggests that CW Aqr is a marginal contact binary with a low mass ratio evolving toward a semi-detached ***,it may merge if the period increases due to ongoing mass transfer accompanied by a lowering in the mass ratio and later oscillate back to the period-decreasing trend due to angular momentum loss over a few cycles of thermal relaxation oscillations followed by instability.

关键词： (stars:)binaries eclipsing-Stars-(stars:)binaries(including multiple) close