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81.
This study deals with the results on the concentration-dependent fluorescence properties of Tb3+-doped calcium aluminosilicate (CAS) glasses of composition (100−x)(58SiO2–23CaO–5Al2O3–4MgO–10NaF in mol%)-x Tb2O3 (x=0, 0.25, 0.5, 1, 2, 4, 8, 16, 24, 32, 40 in wt%). The FTIR reflectance spectra suggested the role of dopant ions as network modifiers in the glass network. The fluorescence spectra of low Tb3+-doped glasses have revealed prominent blue and green emissions from 5D3 and 5D4 excited levels to 7Fj ground state multiplet, respectively. The glass with 2 wt% of Tb2O3 has exhibited maximum intensity of blue emission from 5D3 level, while green emission from 5D4 level has increased linearly up to 24 wt% and showed reduction in the rate of increase for higher Tb2O3 concentrations. The concentration quenching of blue emission (5D3→7Fj) is attributed mainly to the resonant energy transfer (RET) assisted cross-relaxation (CR) among the excited and nearest neighbour unexcited Tb3+ ions in the glass matrix. The decline in rate of increase of green emission (5D4→7Fj) at higher concentrations has been explained due to a possible occurrence of cooperative energy transfers leading to 4f8→4f75d transition interactions. The blue and green emission decay kinetics have been recorded to compute the excited level (5D3 and 5D4) lifetimes, which confirmed the Tb3+ concentration quenching of the blue emission in these glasses. 相似文献
82.
Subhakar Chennupati Ravichandra Potumarthi M. Gopal Rao P. Lakshmi Manga M. Sridevi Annapurna Jetty 《Applied biochemistry and biotechnology》2009,159(2):317-329
Response surface methodology was employed to optimize culture medium for production of lipase with Rhodotorula sp. MTCC 8737. In the first step, a Plackett–Burman design was used to evaluate the effects of different inducers qualitatively.
Of all the seven inducers tested, soybean oil showed significant influence on the lipase production. Further, response surface
studies were conducted to quantitatively optimize by considering linear, interactive, and quadratic effects of test variables.
A novel approach was proposed to optimize the lipase production system by optimizing the responses in terms of yield kinetics
rather than optimizing the direct responses like lipase titer and biomass growth. The coefficient of determination (R
2) calculated for Y
P/S (0.769), Y
P/X (0.799), and Y
X/S (0.847) indicated that the statistical model could explain 76.9%, 79.99%, and 84.7% of variability in the response. 相似文献
83.
S.K. Rout T. Badapanda E. Sinha S. Panigrahi P.K. Barhai T.P. Sinha 《Applied Physics A: Materials Science & Processing》2008,91(1):101-106
BaTi0.6Zr0.4O3 (BTZ) ceramic was synthesized by a soft chemical route. X-ray diffraction at room temperature shows that the sample has cubic
perovskite structure with space group Pm-3m. Temperature dependent dielectric study of the sample has been investigated in
the frequency range from 50 Hz to 1 MHz. The density of the sample was determined using Archimedes’ principle and found to
be ∼ 97% of the X-ray density. The average grain size in the pallet was found to be ∼ 1 μm. The dielectric constant peaks
at temperature Tm which is dependent on the frequency. The dielectric relaxation rate follows the Vogel–Fulcher relation with activation energy = 0.0185 eV,
and freezing temperature = 186 K. All these measurements confirm that BTZ is a relaxor ferroelectric.
PACS 77.22.Jp; 77.84.-s; 77.80.Bh; 77.22.Gm 相似文献
84.
Ajay Sharma Harish Sharma Annapurna Bhargava Nirmala Sharma Jagdish Chand Bansal 《Memetic Computing》2017,9(4):311-331
The power system is a complex interconnected network which can be subdivided into three components: generation, distribution, and transmission. Capacitors of specific sizes are placed in the distribution network so that losses in transmission and distribution is minimum. But the decision of size and position of capacitors in this network is a complex optimization problem. In this paper, Limaçon curve inspired local search strategy (LLS) is proposed and incorporated into spider monkey optimization (SMO) algorithm to deal optimal placement and the sizing problem of capacitors. The proposed strategy is named as Limaçon inspired SMO (LSMO) algorithm. In the proposed local search strategy, the Limaçon curve equation is modified by incorporating the persistence and social learning components of SMO algorithm. The performance of LSMO is tested over 25 benchmark functions. Further, it is applied to solve optimal capacitor placement and sizing problem in IEEE-14, 30 and 33 test bus systems with the proper allocation of 3 and 5-capacitors. The reported results are compared with a network without a capacitor (un-capacitor) and other existing methods. 相似文献
85.
Czechoslovak Mathematical Journal - Let Dm be an elliptic curve over ? of the form y2 = x3 ? m2x + m2, where m is an integer. In this paper we prove that the two points P?1 =... 相似文献
86.
Ram Niranjan R.K. Rout B.S. Tomar P.S. Ramanjaneyulu D.B. Paranjape T.C. Kaushik 《Physics letters. A》2018,382(46):3365-3368
Pulsed neutrons generated in a plasma focus device are used for the thermal neutron activation analysis (TNAA) of selected three elements having widely different half-lives varying from a few seconds to a few days [Dysprosium (Dy), Manganese (Mn) and Gold (Au)]. Neutron pulse having strength of neutrons/pulse with a pulse width of is produced by “MEPF-12” device operated at a filling gas (deuterium + 0.5% krypton) pressure of 3 mbar. The fast 2.45 MeV D–D neutrons are thermalized before irradiating the sample. The decay gammas from the radioisotopes 165mDy (), 56Mn (), and 198Au () produced via reactions, 164Dy()165mDy, 55Mn() 56Mn, and 197Au() 198Au respectively are counted off-line in a lead shielded well type NaI(Tl) detector coupled to a calibrated 2048 channel analyzer. The values of half-lives evaluated from the measured decay gammas, , and respectively for the radioisotopes of Dy, Mn and Au, are seen to be close to the values reported in literature. 相似文献
87.
Mamata Mohapatra K. Rout S. K. Gupta P. Singh S. Anand B. K. Mishra 《Journal of nanoparticle research》2010,12(2):681-686
The present article describes a novel synthesis route for nano-sized goethite (α-FeOOH) using hydrazine sulphate as an additive.
The X-ray diffraction (XRD) peaks of synthesized powder matched well with those of α-FeOOH. Transmission electron microscopy
(TEM) showed the particles of irregular shape in the range of 1–10 nm. Batch adsorption experiments for fluoride uptake were
performed to study the influence of various experimental parameters such as contact time (10 min to 7 h), initial fluoride
concentration (10–150 mg L−1), pH (2–11.6) and the presence of competing anions. The time data fitted well to pseudo-second-order kinetic model. The fluoride
removal passed through broad maxima in pH ranges of 6–8. High adsorption capacity of 59 mg g−1 goethite was obtained. The isothermic data fitted well to Freundlich model. The presence of other ions namely chloride and
sulphate adversely affected fluoride removal. Fluoride from contaminated water sample could be successfully brought down from
10.25 to 0.5 mg L−1. 相似文献
88.
P Meenakshi Raja Rao P Saraswathy G Krishnamurty R K Rout S K H Auluck Anurag Shyam I V Kulkarni Dipak H Oza 《Pramana》1989,32(5):627-639
Optical emission spectroscopic studies were carried out to characterise the plasma leading to the estimation of two plasma parameters, electron density and temperature. These experiments were conducted on a 2 kJ plasma device which is equipped with squirrel cage electrode configuration enclosed in a glass vacuum chamber filled with hydrogen at a pressure of 5 mbar. Spectral emissions obtained from each flash were photographed in the region of 4000–6000 Å using one metre Czerny-Turner spectrograph cum monochromator. Detailed examination of the observed features showed that theH β andH λ lines of hydrogen showed significant broadening of the order of 35 Å FWHM which is due to Stark effect expected in high density plasmas. Further several atomic lines of Cu and Zn from the electrode material (brass) showed broadening which was due to quadratic Stark effect. A comparative study of the broadening of lines obtained in DC arc, hollow cathode and plasma focus was made. Electron density from Stark broadened hydrogen lines and quadratic Stark Coefficient C4 for the CuI and ZnI lines were evaluated. The excitation temperature was determined from the line intensity ratio method using CuI lines. 相似文献
89.
L.N. Patnaik R.K. Satapathy S.N. Patnaik B.K. Misra M.K. Rout 《European Polymer Journal》1980,16(2):117-120
The present communication discusses the kinetics of the retarding effect of phenol on the polymerization of acrylonitrile initiated by azobisisobutyronitrile (AIBN). The results are treated on the basis of the scheme proposed by Tüdös et al. 相似文献
90.