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spectroscopic investigations and luminescence spectra of sm3+ doped soda lime silicate glasses

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Journal of Rare Earths 2009年第5期27卷 773-780页

作者： Y.k. sharma s.s.L. surana R.k. singh Department of Physics Govt. Post Graduate College Rudrapur 263153 (U S Nagar) India Department of Physics J. N. V. University Jodhpur-342001 India Department of Physics Govt. Post Graduate College Rudrapur 263153 (U S Nagar) India

sm3+ doped soda lime silicate glasses co-doped with As2O3 were prepared and characterised by measuring their absorption spectra in UV-VIs/NIR regions and luminescence spectra in the visible region. Judd-Ofelt intensity parameters, Ωλ, were evaluated from the measured intensities of the various absorption bands. Ωλ parameters of these glasses were compared with the Ωλ parameters of other reported sm3+ glasses to study the bonding environment surrounding the sm3+ in the present glasses. Presence of [AsO4]3– tetrahedra in the second coordination sphere around the central sm3+ ion made these glasses less covalent as compared to other oxide glasses but the ratio Ω4/Ω6 of the 1.83 indicated them to be fairly stable. With the help of Ωλ parameters and luminescence data for various emission lines, radiative properties for different emission lines were calculated. The values of radiative properties indicated that 4G5/2→6H7/2 and 4G5/2→6H9/2 transitions responsible for orange luminescence might be used in the development of materials for LED's and other optical devices in the visible region.

关键词： rare earth glasses Judd-Ofelt theory absorption spectroscopy luminescence

Theoretical Approach to Change Blast Furnace Regime With Natural Gas Injection

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Journal of Iron and steel Research International 2013年第9期20卷 40-46页

作者： k s Abdel Halim Central Metallurgical Research and Development Institute(CMRDI)

The operation of blast furnace using natural gas and oxygen enriched blast （composite blast technology） is considered in many countries to be standard operation for a modern blast furnace particularly in certain countries with cheap and stable supply of natural gas. The theoretical flame temperature （TFT） of combustion and the degree of di-rect reduction of iron oxides （rd） are considered as the main controlling parameters of composite blast technology. The calculated values of these parameters are mainly dependent on the amount of air blast consumption. This amount of air blast is measured before entering into blast stoves, Actually, some of air blast is lost through valves of air stoves. Consequently, the real volume of air blast in the furnace is less than the recorded value by amounts of 5%-15% which is not considered in the estimation of rd and TFT. The purpose is to analyze the different methods for es-timation of air blast inside the blast furnaces and develop a theoretical model to calculate air blast eonsumption with high accuracy. Based on the calculation of air blast consumption, a complete roadmap is demonstrated to change the operation regime parameters of blast furnaces working on composite blast technology.

关键词： composite blast technique natural gas blast consumption theoretical flame temperature direct reduc-tion degree iron oxide

Nano-and micron-sized diamond genesis in nature:An overview

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Geoscience Frontiers 2018年第6期9卷 1849-1858页

作者： s.k.simakov LLC“ADAMANT”skolkovo Harchenko 19-A-7HSt.Petersburg194100Russia

There are four main types of natural diamonds and related formation processes. The first type comprises the interstellar nanodiamond particles. The second group includes crustal nano-and micron-scale diamonds associated with coals, sediments and metamorphic rocks. The third one includes nanodiamonds and microndiamonds associated with secondary alteration and replacing of mafic and ultramafic *** fourth one includes macro-, micron-and nano-sized mantle diamonds which are associated with kimberlites, mantle peridotites and eclogites. Each diamond type has its specific characteristics. Nanosized diamond particles of lowest nanometers in size crystallize from abiotic organic matter at lower pressures and temperatures in space during the stages of protoplanetary disk formation. Nano-sized diamonds are formed from organic matter at P-T exceeding conditions of catagenesis stage of lithogenesis. Micron-sized diamonds are formed from fluids at P-T exceeding supercritical water *** diamonds are formed from metal-carbon and silicate-carbonate melts and fluids at P-T exceeding 1150℃ and 4.5 GPa. Nitrogen and hydrocarbons play an important role in diamond *** role in the formation processes increases from macro-sized to nano-sized diamond *** of nitrogen atoms into the diamond structure leads to the stabilization of micron-and nanosized diamonds in the field of graphite stability.

关键词： Diamond Nanodiamonds sediments Meteorites Mantle Organics

Effect of NO_3^--N Enrichment on seawater stress Tolerance of Jerusalem Artichoke (Helianthus tuberosus)

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Pedosphere 2008年第1期18卷 113-123页

作者： s.k.MEHTA College of Resources and Environmental sciences Nanjing Agricultural University

A hydroponic experiment with six treatments, i.e., 0% seawater （control）, 10% seawater, 25% seawater, 0% seawater ＋ N （7.5 mmol L-1 NaNO3）, 10% seawater ＋ N （7.5 mmol L-1 NaO3）, and 25% seawater ＋ N （7.5 mmol L-1 NaNO3）, was carried out to study the effect of nitrogen addition on the growth and physiological and biochemical characteristics of Jerusalem artichoke （Helianthus tuberosus） seedlings under seawater stress. The 10% seawater stress treatment had the least effect on plant growth while at 25% seawater growth was significantly inhibited. The malondialdehyde content and electrolyte leakage in leaves under 10% seawater were similar to those of the control, but significantly higher under the 25% seawater stress. The activities of superoxide dismutase, peroxidase and catalase in the leaves increased concomitantly with increasing seawater concentration and time. Proline and soluble-sugars in the leaves and Na^＋, k^＋, and Cl- contents in shoots and roots increased significantly with the concentration of seawater increasing. Nitrogen addition resulted in increasing fresh and dry weights of shoots and roots compared with seawater treatment without N. Nitrogen supplementation also significantly enhanced the activities of antioxidant enzymes in leaves. Addition of N to seawater enhanced the contents of proline and soluble-sugars in the leaves and k^＋ and total-N in the aerial parts and roots of H. tuberosus, but it resulted in declined concentrations of Na^＋ and Cl- in the aerial parts and roots. Nitrogen addition ameliorated the toxicity of seawater by improving the antioxidative enzymes, accumulating of proiine and soluble-sugars, and altering the distribution of inorganic ions in H. tuberosus.

关键词： Helianthus tuberosus ions distributions malondialdehyde nitrate seawater stress

The Fibered Isomorphism Conjecture for Complex Manifolds

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Acta Mathematica sinica,English series 2007年第4期23卷 639-658页

作者： s.k.ROUsHON school of Mathematics Tata InstituteHomi Bhabha RoadMumbai 400 005India

In this paper we show that the Fibered Isomorphism Conjecture of Farrell and Jones, corresponding to the stable topological pseudoisotopy functor, is true for the fundamental groups of a class of complex manifolds. A consequence of this result is that the Whitehead group, reduced projective class groups and the negative k-groups of the fundamental groups of these manifolds vanish whenever the fundamental group is torsion free. We also prove the same results for a class of real manifolds including a large class of 3-manifolds which has a finite sheeted cover fibering over the circle.

关键词： Complex projective variety Complex surfaces Whitehead group Fibered isomorphism conjecture Negative k-groups

Combustion synthesis and luminescence characteristic of rare earth activated LiCaBO_3

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Journal of Rare Earths 2012年第10期30卷 1005-1008页

作者： N.s. Bajaj s.k. Omanwar Department of Physics SGB Amravati University Amravati-444602 (M.S.)

Lithium calcium borate （LiCaBO3） polycrystalline thermoluminescence （TL） phosphor doped with rare earth （Tb3＋ and Dy3＋） elements was synthesized by novel solution combustion synthesis. The reaction produced very stable crystalline LiCaBO3：D（D=Tb3＋ and Dy3＋） phosphors. These rare earth doped phosphors material showed maximum TL sensitivity with favorable glow curve shape. TL glow curve of X-ray irradiated that LiCaBO3：Tb3＋ and LiCaBO3：Dy3＋ samples showed two major well-separated glow peaks. The TL sensitivity of these phosphors to X-ray radiation was comparable with that of TLD-100（Harshaw）. Photoluminescence spectra of LiCaBO3：Tb3＋ and LiCaBO3：Dy3＋ showed the characteristic Tb3＋ and Dy3＋ peaks respectively. TL response to X-ray radiation dose was linear up to 25 Gy.

关键词： luminescence LiCaBO3 combustion synthesis rare earths kinetics

Indium doping effect on properties of ZnO nanoparticles synthesized by sol–gel method

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Chinese Physics B 2019年第4期28卷 342-348页

作者： s Mourad J El Ghoul k Omri k khirouni Laboratory of Physics of Materials and Nanomaterials Applied at Environment (LaPhyMNE) Faculty of Sciences in Gabes Gabes University Imam Mohammad Ibn saud Islamic University (IMsIU) College of Sciences Department of Physics

Pure ZnO and indium-doped ZnO(In–ZO) nanoparticles with concentrations of In ranging from 0 to 5% are synthesized by a sol–gel processing technique. The structural and optical properties of ZnO and In–ZO nanoparticles are characterized by different techniques. The structural study confirms the presence of hexagonal wurtzite phase and indicates the incorporation of In^(3+) ions at the Zn^(2+) sites. However, the optical study shows a high absorption in the UV range and an important reflectance in the visible range. The optical band gap of In–ZnO sample varies between 3.16 e V and 3.22 e V. The photoluminescence(PL) analysis reveals that two emission peaks appear: one is located at 381 nm corresponding to the near-band-edge(NBE) and the other is observed in the green region. The aim of this work is to study the effect of indium doping on the structural, morphological, and optical properties of ZnO nanoparticles.

关键词： In-doped ZnO nanoparticles sol–gel process structural and optical characterization

Total and Extractable Manganese and Iron in some Cultivated Acid soils of India:status,Distribution and Relationship with some soil Properties

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Pedosphere 2014年第2期24卷 196-208页

作者： s.k.BEHERA A.k.sHUkLA Directorate of Oil Palm Research (DOPR) Indian Institute of soil science (IIss)

A total of 400 surface soil （0-15 cm） samples were collected from cultivated soils representing four soil series, namely, Hariharapur, Debatoli, Rajpora and Neeleswaram in Orissa, Jharkhand, Himachal Pradesh and kerala states of India, respectively, and were analyzed to measure the contents of total and extractable Mn and Fe, to establish the relationship among total and extractable Mn and Fe and soil properties, and to characterize the spatial distribution pattern of Mn and Fe in some cultivated acid soils of India. The contents of total as well as extractable Mn and Fe varied widely with extractants and soil series. However, the amounts of Mn or Fe extracted by diethylene triamine penta-acetic acid （DTPA）, Mehlich 1, Mehlich 3, 0.1 mol L-1 HC1 and ammonium bicarbonate DTPA （ABDTPA） were significantly correlated with each other （P 〈 0.01）. Based on the DTPA-extractable contents and the critical limits （2 mg Mn kg-1 soil and 4.5 mg Fe kg-1 soil） published in the literature, Mn and Fe deficiencies were observed in 7% 23% and 1%-3% of the soil samples, respectively. The content of soil organic carbon （sOC） had greater influence on total and DTPA-extractable Fe than did soil pH. Geostatistical analysis revealed that total and DTPA-extractable Mn and Fe contents in the acid soils were influenced by soil pH, sOC content, and exchangeable cations like potassium, calcium and magnesium. spatial distribution maps of total and DTPA-extractable Mn and Fe in soil indicated different distribution patterns.

关键词： micronutrients extractant geostatistical analysis spatial variability

Pressure Drop of Non-Newtonian Liquid Flow Through Elbows

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Chinese Journal of Chemical Engineering 2000年第4期8卷 388-390页

作者： T.k.Banerjee s.k.DAs Chemical Engineering Department University of Calcutta92A.P.C.RoadCalcutta-700 009IndiaChemical Engineering DepartmentUniversity of Calcutta92A.P.C.RoadCalcutta-700 009India

Experimental data on the pressure drop across different types of elbow for non-Newtonian pseudoplastic liquid flow in laminar condition have been presented. A generalized correlation has been developed for predicting ... 详细信息

关键词： non-Newtonian liquid pseudoplastic elbow