107 research outputs found
Luminescence and optical absorption properties of Nd3+ ions in K-Mg-Al phosphate and fluorophosphate glasses
No full textAbsorption and emission properties and fluorescence lifetimes for the transition of Nd3+ ions embedded in P2O5-K 2O-MgO-Al2O3 (PKMA)-based glasses modified with AlF3 and BaF2 are reported at room temperature. The observed energy levels of Nd3+ ions in these glasses have been analysed through a semi-empirical free-ion Hamiltonian model. The spin-orbit interaction and net electrostatic interaction experienced by the Nd3+ ions follow the trend as PKMA>PKMA+AlF3> PKMA+BaF2 glasses. Judd-Ofelt analysis has been carried out on the absorption spectra of 1.0 mol% Nd3+-doped glasses to predict the radiative properties for the fluorescent levels of the Nd3+ ion. Branching ratios and stimulated emission cross-sections show that the transition of the glasses under investigation has the potential for laser applications. The Inokuti-Hirayama model has been applied to investigate the non-radiative relaxation of the Nd3+ ion emitting state, 4F3/2. Based on the decay curve analysis, concentration quenching of the 4F3/2 emission has been attributed to a cross-relaxation process between the Nd 3+ ions
Synthesis, Structural Properties and Upconversion Emission of Er3+ and Er3+/Yb3+ Doped Nanocrystalline NaNbO3
No full textNanocrystalline sodium niobate (NaNbO3) powders doped with Er3+ and Er3+/Yb3+ ions have been successfully synthesized via Pechini sol–gel method for the first time. The prepared NaNbO3 nanocrystalline compounds are single phase, with orthorhombic structure, and have an average particle size of 60 nm. The Raman investigation reveals a disorder nature of the host. Upon near infrared excitation with an 970 nm radiation, an intense
green and a weaker red upconversion emission was observed from the 2H11/2, 4S3/2 4I15/2 and 4F9/2 4I15/2 transitions respectively, along with 1.55 !m emission from 4F13/2 !4I15/2 transition for both Er3+ doped and Er3+/Yb3+ codoped NaNbO3. A two photon process is found to be the origin of the upconverted emission. An enhancement of nearly 30 times of the upconverted emission is observed in the Er3+/Yb3+ codoped than the Er3+ doped NaNbO3, suggesting a possible use of the present materials in field where the upconversion properties can be useful, such as in solar cells or biomedical applications
Thermodynamic study of polymersurfactant interaction in aqueous system
No full textDepartment of Chemistry, National Postgraduate College, S. K. University, Nandyal-518 502.
Andhra Pradesh, India
E-mail : [email protected] Fax : 91-8514-243115
Manuscript received 24 August 2005, accepted 26 August 2005
The critical micellar concentrations (CMC) of sodium dedecyl sulfate (SDS) in aqueous poly(vinyl pyrrodine) (PVP) (M.W. 40000) solutions have been determined at different temperatures. The CMC of SDS increases with increase in concentration of PVP and decrease with increase of temperatnre. The critical aggregation concentration (CAC) and polymer saturation point (PSP) decrease with increase in temperature. Tbe effect of the increase in polymer concentration of CAC and PSP has been determined. The thermodynamic quantities associated with the PSP are computed
Short-term movements of the penaeid prawn Penaeus indicus H. Milne Edwards in a tropical estuary
Get PDF143-144Short-term movements of Penaeus indicus were investigated through mark-recapture studies in the Upputeru estuary, along the central east coast of India. The passive movements observed were mainly along the axis of the estuary. There was a progressive downward movement towards the mouth of the estuary as they grew in size
Scientometric Study of Publications of ‘Journal of Indian Society of Remote Sensing’
Get PDFThe study attempts to analyse 1008 research publications of ‘Journal of Indian Society of Remote Sensing’ during the period 2010-2019. The present study focused on growth of research output, collaborations trends, citations patterns, contributing countries and organizations. Bibliometrix an R package used for scientometric analysis to achieve the research activities. The study shows that India, China and Iran are the top collaborating countries. The study also shows that the research output of the journal has increased over the years, a significant jump has recorded after 2012. VOSviewer was used to build network maps to know the collaborative zones with respect to Insitute and keyword distributions. The finding of the study shows that Lotka’s law is valid for the present study
District Central Libraries in Rayalaseema Region of Andhra Pradesh: A Study
No full textThis paper focuses on the functioning, library resources, services, and problems existing in the District Central Libraries of Rayalaseema region of Andhra Pradesh. A survey was conducted using questionnaire tool for collecting data from the librarians of the District Central Libraries (DCL) regarding collection development, sources of grants, manpower, library services, physical and ICT infrastructural facilities, etc. The study reveals that majority of the libraries are possessing the collection in the range of 40,000 to 50,000. Further, it is also found that lack of staff, ICT facilities, lack of sufficient budget are the main problems faced by these libraries in Rayalaseema region.</jats:p
A NEW RP-UPLC METHOD FOR THE SEPARATION AND SIMULTANEOUS QUANTIFICATION OF DORZOLAMIDE HCl AND TIMOLOL MALEATE
No full textObjective: This investigation demonstrates a stability-indicating and reliable “reverse-phase ultra-performance liquid chromatography” method to simultaneously quantify timolol maleate and dorzolamide HCl in the pharmaceutical dosage form.
Methods: Successful separation was accomplished using Phenyl column (100 mm x 2.1 mm, 1.7μm) with isocratic type of elution using mobile phase containing Acetonitrile+Ammonium Formate buffer (30:70), respectively with 0.2 ml/min flow rate. The wavelength sensor was attuned at 266 nm to quantify timolol maleate and dorzolamide HCl.
Results: Dorzolamide HCl and timolol maleate peaks were eluted with fine resolution at retention times 0.7 min and 1.5 min, respectively. In the 55.75-334.5 μg/ml and 6.25-37.5 μg/ml concentration ranges for dorzolamide HCl and timolol maleate, the calibration graphs were linear, with regression coefficients of 0.99997 and 0.99991, respectively. The suggested ultra-performance liquid chromatography approach has been shown as sensitive, precise, robust, accurate, specific and stability, indicating through the resolution of dorzolamide HCl and timolol maleate from its degradation-based compounds.
Conclusion: The established ultra-performance liquid chromatography technique was effectively extended to the evaluation of dorzolamide HCl and timolol Maleate in the pharmaceutical dosage form and the test results appeared satisfactory
Determination of elements present in select medicinal plants used by tribal people for therapeutic purposes
No full textTwelve medicinal plants have been collected from the Paderu agency area (at high altitude) of Visakhapatnam District, AP state of India, which are used for traditional treatment by local tribal people. Concentrations of macro and micro or trace elements of these medicinal plants have been determined by using spectra obtained due to energy dispersive X-ray fluorescence spectrometer coupled with Si (Li) detector. Six macro (K > Ca > P > Cl > Si > S), ten micro and or trace elements (Fe > Mn > Zn > V > Cu > Ni > I > Cr > Mo > Se) are obtained; these elements used to analyze with physiological and metabolic importance of human beings. Further obtained results are interpreted with curative properties of different diseases. Thus, the role of observed elements for therapeutic usage relating to the undertaken medicinal plants those using in the Paderu agency area have been corroborated. Statistical analysis also carried out by using linear correlation analysis
METHOD DEVELOPMENT AND VALIDATION OF NORETHINDRONE ACE-TATE ASSAY AND ITS RELATED IMPURITIES IN API AND PHARMACEUTICAL FORMULATION WITH ORTOGONAL DETECTOR TECHNQUES
Get PDFObjective: To develop and validate a sensitive and stability indicating gradient reverse phase ultra-high performance(UHPLC-PDA) liquid chromatography with photodiode array(PDA) and mass spectroscopy (MS) of Norethindrone Acetate (NA) assay and organic impurities (OI) in active pharmaceutical Ingredient(API) and Pharmaceutical Formulation (PF).Methods: The chromatographic conditions were optimized using Zorbax SB-C18 analytical UHPLC column with the dimensions (100 x 2.1) mm and 1.8 μm particle sizes. The mobile phase consisted of water (solution A) and acetonitrile (solution B) with gradient elution as mentioned time (min)/% Solution B: Initial/40,0.2/40, 9.2/55,12.0/55,12.2/90,15.5/90, 15.8/40 and 18.0/40. The flow rate was at the rate of 0.4 ml/min and the detection wavelengths were 254 nm and 210 nm. The column was kept at 40 °C and the injection volume was 5 μL. Stability of NA sample in different conditions was investigated by exposing the drug to stress study utilizing acid, base, oxidation, thermal, Humidity and photolytic.Results: There was no interference from excipients, impurities or degradation products at the retention time of NA about 9.1 min indicating the specificity of the method.The drug showed good stability under oxidation, thermal, humidity and photolytic conditions, but significant degradation was observed under acid and base conditions. The procedure was validated for specificity, linearity, accuracy, precision and robustness. The degradation products were well resolved from NA and its impurities. The obtained LOD (Limit of detection) values are 0.001% to 0.015% and LOQ (Limit of quantification) values are 0.003% to 0.05% of impurities.Conclusion: A sensitive, rapid, specific and stability indicating gradient Reverse Phase UHPLC-PDA-PDA with MS (Orthogonal detectors) method for the determination of NA for the assay and organic impurities was successfully developed. The developed method was validated to be specific, linear, accurate, precise and robust. The peak purity and LC-MS test results confirmed that the NA peak was homogenous in all stress samples and the mass balance was found to be more than 99%, thus proving the stability indicating power of the metho
METHOD DEVELOPMENT AND VALIDATION OF NORETHINDRONE ACE-TATE ASSAY AND ITS RELATED IMPURITIES IN API AND PHARMACEUTICAL FORMULATION WITH ORTOGONAL DETECTOR TECHNQUES
No full textObjective: To develop and validate a sensitive and stability indicating gradient reverse phase ultra-high performance(UHPLC-PDA) liquid chromatography with photodiode array(PDA) and mass spectroscopy (MS) of Norethindrone Acetate (NA) assay and organic impurities (OI) in active pharmaceutical Ingredient(API) and Pharmaceutical Formulation (PF).Methods: The chromatographic conditions were optimized using Zorbax SB-C18 analytical UHPLC column with the dimensions (100 x 2.1) mm and 1.8 μm particle sizes. The mobile phase consisted of water (solution A) and acetonitrile (solution B) with gradient elution as mentioned time (min)/% Solution B: Initial/40,0.2/40, 9.2/55,12.0/55,12.2/90,15.5/90, 15.8/40 and 18.0/40. The flow rate was at the rate of 0.4 ml/min and the detection wavelengths were 254 nm and 210 nm. The column was kept at 40 °C and the injection volume was 5 μL. Stability of NA sample in different conditions was investigated by exposing the drug to stress study utilizing acid, base, oxidation, thermal, Humidity and photolytic.Results: There was no interference from excipients, impurities or degradation products at the retention time of NA about 9.1 min indicating the specificity of the method.The drug showed good stability under oxidation, thermal, humidity and photolytic conditions, but significant degradation was observed under acid and base conditions. The procedure was validated for specificity, linearity, accuracy, precision and robustness. The degradation products were well resolved from NA and its impurities. The obtained LOD (Limit of detection) values are 0.001% to 0.015% and LOQ (Limit of quantification) values are 0.003% to 0.05% of impurities.Conclusion: A sensitive, rapid, specific and stability indicating gradient Reverse Phase UHPLC-PDA-PDA with MS (Orthogonal detectors) method for the determination of NA for the assay and organic impurities was successfully developed. The developed method was validated to be specific, linear, accurate, precise and robust. The peak purity and LC-MS test results confirmed that the NA peak was homogenous in all stress samples and the mass balance was found to be more than 99%, thus proving the stability indicating power of the method</jats:p
- …
