Browsing by Author "Vineet Kumar Rai"

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A comparative study of FIR and FL based temperature sensing schemes: An example of Pr3+
(2007) Vineet Kumar Rai; S.B. Rai
Temperature sensing schemes based on fluorescence intensity ratio and fluorescence lifetimes have been compared on the basis of experimental and theoretical approaches, taking Pr3+ as an example. The responses of the two techniques based on their sensitivities has also been discussed. © Springer-Verlag 2007.
Energy transfer between Er3+:Sm3+codoped TeO2-Li2O glass
(2008) Garima Tripathi; Vineet Kumar Rai; A. Rai; S.B. Rai
The energy transfer in Er3+: Sm3+ codoped binary TeO2-Li2O (TLO) glass has been studied using 532 nm laser radiation on the basis of fluorescence intensity and the lifetime measurements. It is observed that the trace of erbium ion can be utilized to sensitize the samarium. The mechanism involved in the present case is found to be dipole-dipole. The energy transfer efficiencies, probabilities of energy transfer and the average donor acceptor distance has been evaluated. © 2008 Elsevier B.V. All rights reserved.
Estimation of drinking water supply and its future trends in Varanasi city, India
(University of Craiova, Faculty of Social Sciences, Department of Geography, 2018) Vineet Kumar Rai; Pravin Kumar; Praveen Kumar Rai
The current study shows the estimation of drinking water supply, future trends and related issues in Varanasi City, India. Varanasi (from 25 0 13'N to 25 0 24'N latitudes and from 82 0 54'E to 83 0 04'E longitude) is one of the most important and historic city located almost in the Middle Ganga valley in the northern plain of India. For the convenience of civic administration, the city is presently divided into 90 wards and for the purpose of extending adequate and safe water supply facilities to the entire area, the city has been divided presently into 16 water supply zones of which 5 zones lie in the trans-Varuna area and the remaining 11 zones in the cis-Varuna area. The present work is based on the secondary sources of data which are obtained from Water Supply Department (Jal Sansthan), Nagar Nigam (Municipal Corporation) of Varanasi. In the first phase of the study, data pertaining to ward wise generation of water supply is collected from Water Supply Department, NNV (Nagar Nigam Varanasi). Informal focused group discussion, PRA (Participatory Action Research), and observation technique were applied to get the first hand information about the water supply scenario in the city. In the second phase of the study, Arc GIS 10.1 software was used to create maps for estimation of water supply management. The population growth in Varanasi from 2011 to 2041 is estimated to have a growth of 21% in 30 years at a rate of 2.25 % per year. This growth rate is considered in the model from 2011 to 2041 to predict the water demand in the city. The data was collected from various municipalities as per the office records. It is estimated that the amount of drinking water requirement forecasted for 2021, 2031 and 2041 is 0.49, 0.76 and 1.17 Billion liters per day respectively in Varanasi City. These data show that with an increase in population, the water demand is also increasing decade after decade. Increasing population growth rate, decreasing surface water resources, overexploitation of groundwater, deterioration of ground water quality and poor sewage treatment are the major water supply related issues in Varanasi city, India. © 2018 University of Craiova, Faculty of Social Sciences, Department of Geography. All rights reserved.
Frequency upconversion in Pr3+-Li2O-TeO2 binary glass by decay curve analysis
(2007) Vineet Kumar Rai; S.B. Rai
Using the decay curve analysis frequency upconversion under continuous wave NIR laser radiation (∼890 nm) following the non-resonant excitation at higher energies than 1G4 level has been reported. The decay curve of the antistokes emission (3P0 → 3H4) shows similar behavior as that of the stokes emission (3P0 → 3H4) and does not show any rise time attributing to the excited state antistokes absorption assisted by phonon emission. The covalency, bonding parameters and nephalauxetic effect for the present system has also been determined. © 2006 Elsevier B.V. All rights reserved.
Management of natural resources through integrated watershed management in nana kosi micro watershed, district almora, India
(EM International, 2021) Ashutosh Singh; Praveen Kumar Rai; Ghanashyam Deka; Brototi Biswas; Dipak Prasad; Vineet Kumar Rai
The watershed has been recognised as a unit for integrated resource management, where management is not merely limited to land, water and biomass; but also concerned with integration for self-reliance and holistic development of the rural population. The Uttarakhand Himalaya present an incomprehensible mixed risk prone ecosystem largely due to land degradation, hydrological discrepancies, low productivity, soil erosion and a pauperized subsistence economy. There is a need for sustainable strategy for redressal of the pressing natural and socio-economic problems. In an operational context, this would mean integrating different uses and management of resources through an inter-disciplinary approach, and towards alleviation of poverty. Keeping in this, this study has been focused on the analysis and management of natural resources through Integrated Watershed Management (IWM) in high altitude of Himalayan area of Nana Kosi river watershed. The present paper assesses the prevailing conditions in the Nana Kosi micro watershed and suggests strategies for the sustainable development. © EM International.
Mechanistic approaches and factors regulating microalgae mediated heavy metal remediation from the aquatic ecosystem
(Elsevier B.V., 2023) Kapil D. Pandey; Sandeep Kumar Singh; Livleen Shukla; Vineet Kumar Rai; Rahul Prasad Singh; Priya Yadav; Rajan Kumar Gupta; Prashant Kumar Singh; Kaushalendra; Ajay Kumar
Heavy metal is considered to be most lethal and toxic when entered in food chain along with terrestrial aquatic system. The waste water is an important source of deposition of heavy metals or toxic elements in the aquatic ecosystem, Hence remediation becomes very important for the survivality of living organisms present in the aquatic ecosystem. Microalga technology plays vital role in heavy metal remediation from the aquatic ecosystem as microalgae dominates over other biological organism and other traditional method to detoxify heavy metals in an eco-friendly manner. The remediated heavy metals are taken up by the microalgae as a nutrient source, which helps in producing biomass which is valorize into different forms of energy as world is facing immense energy crises, so microalgae is considered to be alternative form of fossil fuel which helps in overcoming energy crisis by producing different type of biofuel. © 2023 Elsevier Inc.
Optical properties and upconversion in Pr3+ doped in aluminium, barium, calcium fluoride glass-II
(2005) Anita Rai; Vineet Kumar Rai
The absorption and the fluorescence spectra of Pr3+ ion doped in aluminium, barium, calcium fluoride (ABCF) glass have been studied. Judd-Ofelt theory has been used to derive the optical parameters viz. the oscillator strength, transition probability, branching ratio, stimulated emission cross-section etc. We have also calculated nephelauxetic effect, covalency and bonding parameters for Pr3+ in the present lattice. A broad band upconversion has been observed at different wavelengths throughout the visible region when pumped with 810 nm radiation from a Ti-Sapphire laser.
Optical properties and upconversion in Pr3+ doped in aluminum, barium, calcium fluoride glass - I
(2006) Anita Rai; Vineet Kumar Rai
The absorption and the fluorescence spectra of Pr3+ ion doped in aluminum, barium, calcium fluoride (ABCF) glass have been studied. Judd-Ofelt theory has been used to derive the optical parameters, viz. the oscillator strength, transition probability, branching ratio, stimulated emission cross section, etc. A broadband upconversion has been observed at different wavelengths throughout the visible region when pumped with 810 nm radiation from a Ti-sapphire laser. © 2005 Elsevier B.V. All rights reserved.
Optical studies of Dy3+ doped tellurite glass: Observation of yellow-green upconversion
(2006) Vineet Kumar Rai; S.B. Rai; D.K. Rai
Optical absorption and fluorescence spectra of Dy3+ doped tellurite glass have been studied and Judd-Ofelt theory has been used to derive its optical properties. The effect of temperature on the fluorescence yield and fluorescence quenching for higher concentrations of Dy3+ has been studied and the mechanism involved discussed. It is found that the fluorescence intensity is larger at lower temperature. The lifetime of the 4F 9/2 level has been measured and found to decrease with concentration as well as temperature. Intense upconversion has also been observed in the yellow-green region when pumped with NIR (∼862 nm) radiation. An explanation of the same involving energy transfer is offered. © 2005 Elsevier B.V. All rights reserved.
Optical transitions of Dy3+ in tellurite glass: Observation of upconversion
(2004) Vineet Kumar Rai; S.B. Rai
Dy3+ doped tellurite glasses were prepared and its optical absorption, fluorescence and upconversion have been studied. The absorption data has been used to calculate the Judd-Ofelt parameters, oscillator strengths along with transition probability, branching ratio, etc. The lifetime of the F9/24 level is found to be 0.66 ms for 1.0 mol% of Dy3+ doped in tellurite glass. NIR to visible upconversion has been observed at room temperature. The increase in upconversion luminescence at lower temperature indicates that upconversion is not due to a thermally activated process. The quantum efficiency of the F9/24→H13/2 transition is found to be ∼0.17 and the upconversion efficiency is ∼0.022. The strong dependence of the upconversion efficiency on the Dy3+ concentration reveals that the upconversion is due to energy transfer interaction. © 2004 Elsevier Ltd. All rights reserved.
Overtone bands in aniline and its chloro-derivatives - A low concentration study
(2003) Vineet Kumar Rai; S.B. Rai; D.K. Rai
Overtone spectra of aniline and its o-and m- chloro-derivatives mixed with carbon tetrachloride have been studied at different dilutions. Vibrational frequency and anharmonicity constants for the C-H stretch vibration and for the symmetric and asymmetric N-H stretch vibrations have been determined. The presence of intermolecular hydrogen bonding has been noted in all the three molecules. Intramolecular hydrogen bonding involving N-H⋯Cl has also been detected in o-chloroaniline. © 2002 Published by Elsevier Science B.V.
Overtone spectra of aniline derivatives
(2004) Vineet Kumar Rai; Amareswar Rai; D.K. Rai; S.B. Rai
Overtone spectra of 2-ethylaniline, N-methylaniline, N-ethylaniline, N,N-dimethylaniline and N,N-diethylaniline have been studied in 2500-15 000 cm-1 region. Vibrational frequency and anharmonicity constants for aryl/alkyl C-H stretch and N-H stretch vibrations have been determined. The effect of substitution of C2H5 group on the ortho position in the ring and CH3/C2H5 at the positions of the H-atom in NH2 group has been studied in these molecules. It is noted that the aryl C-H stretching frequency and the N-H stretching frequency is appreciably increased due to the replacement of H in NH2 group by CH3/C2H5. These experimental observations are well supported by theoretical calculations for charge density on N-atom using molecular orbital AM1 method. © 2003 Elsevier B.V. All rights reserved.
Plant-Endophyte Interaction during Biotic Stress Management
(MDPI, 2022) Parul Pathak; Vineet Kumar Rai; Hasan Can; Sandeep Kumar Singh; Dharmendra Kumar; Nikunj Bhardwaj; Rajib Roychowdhury; Lucas Carvalho Basilio de Azevedo; Kaushalendra; Hariom Verma; Ajay Kumar
Plants interact with diverse microbial communities and share complex relationships with each other. The intimate association between microbes and their host mutually benefit each other and provide stability against various biotic and abiotic stresses to plants. Endophytes are heterogeneous groups of microbes that live inside the host tissue without showing any apparent sign of infection. However, their functional attributes such as nutrient acquisition, phytohormone modulation, synthesis of bioactive compounds, and antioxidant enzymes of endophytes are similar to the other rhizospheric microorganisms. Nevertheless, their higher colonization efficacy and stability against abiotic stress make them superior to other microorganisms. In recent studies, the potential role of endophytes in bioprospecting has been broadly reported. However, the molecular aspect of host–endophyte interactions is still unclear. In this study, we have briefly discussed the endophyte biology, colonization efficacy and diversity pattern of endophytes. In addition, it also summarizes the molecular aspect of plant–endophyte interaction in biotic stress management. © 2022 by the authors.
Pr 3+ doped lithium tellurite glass as a temperature sensor
(2006) Vineet Kumar Rai; D.K. Rai; S.B. Rai
Optical properties of Pr 3+ doped lithium tellurite glass suitable for drawing fiber have been studied and profile of energy levels obtained. An excitation with 457.9 nm line of Ar + gives strong fluorescence from 3P 0,1 and 1D 2 levels to various low-lying levels. It is found that the fluorescence intensity ratio from 3P 1 and 3P 0 levels to a common lower level viz. 3H 5 at different temperatures can be used to measure the temperature. © 2005 Elsevier B.V. All rights reserved.
Spectroscopic properties of Pr3+ doped in tellurite glass
(2005) Vineet Kumar Rai; S.B. Rai; D.K. Rai
The absorption and fluorescence spectra of Pr3+ doped in tellurite glass has been recorded and analyzed in terms of Judd-Ofelt theory. The lifetime of 3P0 and 3P1 levels has been measured. Fluorescence quenching has been observed for higher concentrations of Pr3+ ion. The temperature dependence of the fluorescence intensity and the lifetime of the 3P0 level has been investigated and found that they decrease with the increase of the temperature. © 2005 Elsevier B.V. All rights reserved.
Spectroscopic studies of Eu3+ doped calibo glass: Effect of the addition of barium carbonate, energy transfer in the presence of Sm3+
(2006) Garima Tripathi; Vineet Kumar Rai; S.B. Rai
Optical properties of Eu3+ doped calibo glass has been studied in presence and absence of BaO and their dependence on BaO concentration explored. It is found that the fluorescence intensity increases and approaches maximum for 10% of BaO content but get quenched for higher concentrations. The energy transfer between two asimilar rare earth ions (Sm3+:Eu3+) doped in calibo glass has been verified on the basis of changes in fluorescence yield. © 2006 Elsevier B.V. All rights reserved.
Spectroscopy and upconversion of Dy3+ doped in sodium zinc phosphate glass
(2005) Garima Tripathi; Vineet Kumar Rai; S.B. Rai
Optical absorption and fluorescence spectra of Dy3+ doped in sodium zinc phosphate glasses have been reported. Judd-Ofelt theory has been applied to analyze the spectra and determine the optical parameters such as transition probabilities, radiative lifetime, stimulated emission cross-section, etc. The fluorescence intensity of Dy3+ corresponding to 4F9/2 → 6H13/2 transition increases with increasing concentration of Dy3+ but at higher concentrations, concentration quenching is observed. The radiative lifetime of the 4F9/2 level at 1 mol% concentration of Dy3+ in this host is found to be 541 μs. Emission corresponding to 4F9/2 → 6H13/2 transition (570 nm) is observed on excitation with NIR radiation due to upconversion. An attempt is made to explain this observation. © 2005 Elsevier B.V. All rights reserved.
Temperature sensing behaviour of the stark sublevels
(2007) Vineet Kumar Rai; S.B. Rai
The temperature dependence of the fluorescence intensity ratio of the two stark components of 4S3/2 → 4I15/2 transition using 800 nm radiation from a Ti-sapphire laser pumped by the second harmonic of Nd:YVO4 laser has been augmented in Er3+ doped tellurite glass. It is emphasized that even the two stark components of 4S3/2 → 4I15/2 transition may be utilized to monitor the temperature within 300-550 K with its appreciable sensitivity. © 2007 Elsevier B.V. All rights reserved.
Upconversion and temperature sensing behavior of Er3+ doped Bi2O3-Li2O-BaO-PbO tertiary glass
(Elsevier, 2007) Garima Tripathi; Vineet Kumar Rai; S.B. Rai
Spectroscopic properties of Er3+ doped bismuth glass has been reported on the basis of J-O theory. The upconversions observed due to energy transfer in Er3+ doped bismuth glass have been studied and explained. The effect of temperature on the luminescence intensity of the bands has been monitored and it is inferred that these may be used to sense the temperature with appreciable sensitivity. The nephalauxetic effect, covalency and bonding parameters for Er3+ in the present glass have been determined. © 2006 Elsevier B.V. All rights reserved.
Upconversion in Er3+-doped Bi2O3-Li2O-BaO-PbO tertiary glass
(2007) Garima Tripathi; Vineet Kumar Rai; D.K. Rai; S.B. Rai
Radiative properties of Er3+-doped tertiary bismuth glass has been analyzed by the Judd-Ofelt theory. NIR to visible upconversion in the Er3+-doped glass has been reported. The mechanism for the upconversion is explained on the basis of quadratic dependence on excitation power and on the energy-matching scheme. Energy transfer is noted as the dominant process including the long-lived 4I11/2 level as the intermediate state for the green and red upconversion emissions. The effect of temperature on the fluorescence intensity of the two bands due to 2H11/2 → 4I15/2 and 4S3/2 → 4I15/2 transitions as well as on the transitions due to Stark components of the 4S3/2 level have been monitored and it is concluded that their intensity ratio may serve as better temperature sensing device. © 2006 Elsevier B.V. All rights reserved.