Sample records for laugis tnu lehtla

  1. TNU-9 Zeolite: Al Distribution and Extra-Framework Sites of Divalent Cations.


    Karcz, Robert; Dedecek, Jiri; Supronowicz, Barbara; Thomas, Haunani M; Klein, Petr; Tabor, Edyta; Sazama, Petr; Pashkova, Veronika; Sklenak, Stepan


    The TNU-9 zeolite (TUN framework) is one of the most complex zeolites known. It represents a highly promising matrix for both acid and redox catalytic reactions. We present a newly developed approach which includes 29Si and 27Al (3Q) MAS NMR spectroscopy, Co(II) cations as probes monitored by UV-vis and FTIR spectroscopies, and extensive periodic DFT calculations including molecular dynamics to investigate the Al distribution in the TUN framework and the location of Al pairs and divalent cations in extra-framework cationic positions. Our study shows that 40 and 60 % of Al atoms in the TNU-9 zeolite are isolated single Al atoms and Al pairs, respectively. The Al pairs are present in two types of six member rings forming the corresponding α and β (15 and 85 %, respectively, of Al pairs) sites for bare divalent cations. The α site is located on the TUN straight channel wall and it connects two channel intersections. The suggested near planar β site is present at the channel intersection.

  2. Study of the effects of solar activities on the ionosphere as observed by VLF signals recorded at TNU station, Vietnam

    NASA Astrophysics Data System (ADS)

    Tan, L. M.


    A SuperSID monitor installed at Tay Nguyen University (TNU), Vietnam is used to detect the temporal variations of Very Low Frequency (VLF) signals during 2013 and 2014 to understand the responses of the ionosphere to sunset/sunrise transitions and solar flares. Two VLF station signals are tracked, JJI/22.2 kHz in Japan and NWC/19.8 kHz in Australia. Results show that the effects of sunrise, sunset and solar flares on the NWC signal are more significantly different than those on the JJI signal. Sunset and sunrise spikes only occur on the JJI-TNU path because of longitudinal differences between the receiver and transmitter. Two sunset dips and three sunrise dips appear on the NWC signal during summer season. During intense solar flares, the dips occur after the maximum disturbance of the VLF signals for the North-South path. The appearance of these dips is explained by modal interference patterns. Observing temporal variations of sunrise and sunset dips or spikes of VLF signals during different seasons enhances the understanding of the behavior of the ionosphere.

  3. A new metal exchanged zeolite for a present environmental problem. An in-situ XAS study

    NASA Astrophysics Data System (ADS)

    Alonso-Escobar, C.; Franch-Martí, C.; Palomares, A. E.; Rey, F.; Guilera, G.


    The medium pore zeolite, TNU-9, is prepared and studied for the selective catalytic reduction (SCR) of NO using C3H8 as the reducing agent. The catalytic activity of TNU-9 zeolites for the SCR is comparable to other known highly active zeolites but with the advantage of TNU-9 of having almost the same catalytic performance in the presence of H2O during reaction. The nature and behaviour of Cu and Co active sites contained in the TNU-9 catalysts have been studied under operation conditions using X-ray Absorption Spectroscopy (XAS) to understand the key parameters controlling the performance of this reaction.1 It was found that the well dispersed Cu and Co centres need to be in a mixed valence state to obtain good catalytic results for the SCR and that the catalytic performance is related to the topology of the TNU-9 itself.

  4. US EPA, Pesticide Product Label, PROPYLENE OXIDE, 12/21 ...

    EPA Pesticide Factsheets


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  5. Prime Contract Awards by Service Category and Federal Supply Classification, Fiscal Years 1973, 1974, 1975, 1976.

    DTIC Science & Technology


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  6. Environmental Impact Statement. Peacekeeper Rail Garrison Program. Volume 1

    DTIC Science & Technology


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  7. Regional study of the Archean to Proterozoic crust at the Sudbury Neutrino Observatory (SNO+), Ontario: Predicting the geoneutrino flux

    NASA Astrophysics Data System (ADS)

    Huang, Yu; Strati, Virginia; Mantovani, Fabio; Shirey, Steven B.; McDonough, William F.


    SNO+ detector that is currently under construction in Ontario, Canada, will be a new kiloton-scale liquid scintillation detector with the capability of recording geoneutrino events that can be used to constrain the strength of the Earth's radiogenic power, and in turn, to test compositional models of the bulk silicate Earth (BSE). We constructed a detailed 3-D model of the regional crust centered at SNO+ from compiled geological, geophysical, and geochemical information. Crustal cross sections obtained from refraction and reflection seismic surveys were used to characterize the crust and assign uncertainties to its structure. The average Moho depth in the study area is 42.3 ± 2.6 km. The upper crust was divided into seven dominant lithologic units on the basis of regional geology. The abundances of U and Th and their uncertainties in each upper crustal lithologic unit were determined from analyses of representative outcrop samples. The average chemical compositions of the middle and lower crust beneath the SNO+ region were determined by coupling local seismic velocity profiles with a global compilation of the chemical compositions of amphibolite and granulite facies rocks. Monte Carlo simulations were used to predict the geoneutrino signal originating from the regional crust at SNO+ and to track asymmetrical uncertainties of U and Th abundances. The total regional crust contribution of the geoneutrino signal at SNO+ is predicted to be 15.6-3.4+5.3 TNU (a Terrestrial Neutrino Unit is one geoneutrino event per 1032 target protons per year), with the Huronian Supergroup near SNO+ dominantly contributing 7.3-3.0+5.0 TNU to this total. Future systematically sampling of this regional unit and denser seismic surveys will better model its composition and structure, and thus reduce the uncertainty on geoneutrino signal at SNO+. The bulk crustal geoneutrino signal at SNO+ is estimated to be 30.7-4.2+6.0 TNU, which is lower than that predicted in a global-scale reference

  8. Electronic Principles Inventory, Lowry Technical Training Center

    DTIC Science & Technology


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  9. Williams AFB, Arizona Revised Uniform Summary of Surface Weather Observations (RUSSWO) Parts A-F.

    DTIC Science & Technology


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  10. Installation Restoration General Environmental Technology Development. Field Demonstration of Incinerator Feed System for Explosives-Contaminated Soils. Volume 2. Appendices.

    DTIC Science & Technology


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  11. Expected geoneutrino signal at JUNO

    NASA Astrophysics Data System (ADS)

    Strati, Virginia; Baldoncini, Marica; Callegari, Ivan; Mantovani, Fabio; McDonough, William F.; Ricci, Barbara; Xhixha, Gerti


    Constraints on the Earth's composition and on its radiogenic energy budget come from the detection of geoneutrinos. The Kamioka Liquid scintillator Antineutrino Detector (KamLAND) and Borexino experiments recently reported the geoneutrino flux, which reflects the amount and distribution of U and Th inside the Earth. The Jiangmen Underground Neutrino Observatory (JUNO) neutrino experiment, designed as a 20 kton liquid scintillator detector, will be built in an underground laboratory in South China about 53 km from the Yangjiang and Taishan nuclear power plants, each one having a planned thermal power of approximately 18 GW. Given the large detector mass and the intense reactor antineutrino flux, JUNO aims not only to collect high statistics antineutrino signals from reactors but also to address the challenge of discriminating the geoneutrino signal from the reactor background. The predicted geoneutrino signal at JUNO is terrestrial neutrino unit (TNU), based on the existing reference Earth model, with the dominant source of uncertainty coming from the modeling of the compositional variability in the local upper crust that surrounds (out to approximately 500 km) the detector. A special focus is dedicated to the 6° × 4° local crust surrounding the detector which is estimated to contribute for the 44% of the signal. On the basis of a worldwide reference model for reactor antineutrinos, the ratio between reactor antineutrino and geoneutrino signals in the geoneutrino energy window is estimated to be 0.7 considering reactors operating in year 2013 and reaches a value of 8.9 by adding the contribution of the future nuclear power plants. In order to extract useful information about the mantle's composition, a refinement of the abundance and distribution of U and Th in the local crust is required, with particular attention to the geochemical characterization of the accessible upper crust where 47% of the expected geoneutrino signal originates and this region contributes

  12. Size of knots in ring polymers.


    Marcone, B; Orlandini, E; Stella, A L; Zonta, F


    We give two different, statistically consistent definitions of the length l of a prime knot tied into a polymer ring. In the good solvent regime the polymer is modeled by a self avoiding polygon of N steps on cubic lattice and l is the number of steps over which the knot "spreads" in a given configuration. An analysis of extensive Monte Carlo data in equilibrium shows that the probability distribution of l as a function of N obeys a scaling of the form p(l,N) approximately l(-c)f(l/N(D)) , with c approximately equal to 1.25 and D approximately equal to 1. Both D and c could be independent of knot type. As a consequence, the knot is weakly localized, i.e., approximately N(t) , with t=2-c approximately equal to 0.75 . For a ring with fixed knot type, weak localization implies the existence of a peculiar characteristic length l(nu) approximately N(tnu) . In the scaling approximately N(nu) (nu approximately equal to 0.58) of the radius of gyration of the whole ring, this length determines a leading power law correction which is much stronger than that found in the case of unrestricted topology. The existence of this correction is confirmed by an analysis of extensive Monte Carlo data for the radius of gyration. The collapsed regime is studied by introducing in the model sufficiently strong attractive interactions for nearest neighbor sites visited by the self-avoiding polygon. In this regime knot length determinations can be based on the entropic competition between two knotted loops separated by a slip link. These measurements enable us to conclude that each knot is delocalized (t approximately equal to 1) .

  13. Water quality and pollution status of Chambal river in National Chambal Sanctuary, Madhya Pradesh.


    Saksena, D N; Garg, R K; Rao, R J


    The physico-chemical characteristics of Chambal river water in National Chambal sanctuary (Madhya Pradesh) have been studied. The stretch of Chambal river contained in the National Chambal sanctuary (located at 25 degrees 23'-26 degrees 52'N, 76 degrees 28'-79 degrees 15'E) is extending up to 600 km downstream from Kota (Rajasthan) to the confluence of the Chambal with Yamuna river (Etawah). The river flow in Madhya Pradesh spans up to approximately 400 km. Three sampling stations viz., Station A--near Palighat, district Sheopurkalan, Station B--near Rajghat, district Morena and Station C--near Baraighat, district Bhind were established for the collection of water samples during April, 2003 to March, 2004. The water quality parameters namely transparency (12.12-110 cm), colour (transparent-very turbid), turbidity (1-178 TNU), electrical conductivity (145.60-884 microS cm(-1)), total dissolved solids (260-500 mgl(-1)), pH (7.60-9.33), dissolved oxygen (4.86-14.59 mgl(-1)), free carbon dioxide (0-16.5 mgl(-1)), total alkalinity (70-290 mgl(-1)), total hardness (42-140 mgl(-1)), chloride (15.62-80.94 mgl(-1)), nitrate (0.008-0.025 mgl(-1)), nitrite (0.002-0.022 mgl(-1)), sulphate (3.50-45 mgl(-1)), phosphate (0.004-0.050 mgl(-1)), silicate (2.80-13.80 mgl(-1)), biochemical oxygen demand (0.60-5.67 mgl(-1)), chemical oxygen demand (2.40-26.80 mgl(-1)), ammonia (nil-0.56 mgl(-1)), sodium (14.30-54.40 mgl(-1)) and potassium (2.10 mgl(-1)-6.30 mgl(-1)) reflects on the pristine nature of the river in National Chambal sanctuary. On the basis of various parameters studied, Chambal river in this stretch can be placed under the category of oligosaprobic. The water quality analysis, indicated that the riverwater in the sanctuary area is pollution free and can serve as a good habitat for many aquatic animals including endangered species.