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11. Synthesis and nanoscale characterization of {(N[H.sub.4]).sub.4}Th[F.sub.8] and ThNF

Author

Silva, G. W. Chinthaka, Yeamans, Charles B., Cerefice, Gary S., Sattelbergers, Alfred P., and Czerwinski, Kenneth R.

Subjects
Chemical synthesis -- Research, Ammonium chloride -- Structure, Ammonium chloride -- Properties, Ammonium chloride -- Research, Ammonium compounds -- Structure, Ammonium compounds -- Properties, Ammonium compounds -- Research, Ammonium paratungstate -- Structure, Ammonium paratungstate -- Properties, Ammonium paratungstate -- Research, Thorium -- Structure, Thorium -- Properties, Thorium -- Research, Chemistry
Published
2009

13. Degradabilidade in situ das silagens de variedades de cana-de-açúcar com aditivos

Author

Silva, G. W. V., Rocha Júnior, V.R., Rocha, W.J.B., Reis, S.T., Pires, D.A.A., Antunes, A.P.S., Almeida Filho, S. H. C., Oliveira, L. M., Caldeira, L.A., Souza, V.M. de, Silva, G. W. V., Rocha Júnior, V.R., Rocha, W.J.B., Reis, S.T., Pires, D.A.A., Antunes, A.P.S., Almeida Filho, S. H. C., Oliveira, L. M., Caldeira, L.A., and Souza, V.M. de

Abstract

The aim of this work was to evaluate the in situ degradability of the dry matter, crude protein and neutral detergent fiber of two sugarcane varieties ensiled with additives. The evaluation of the degradability was carried out according to a random blocks design, in factorial scheme 2 x 6, being two cane varieties (IAC 86-2480 and RB 86-7515), and five additives (urea, NaOH, CaO, corn and Lactobacillus buchneri), plus the control silage, with 3 blocks (animals). The NaOH and the CaO increased the values of soluble fraction and the effective degradability of dry matter. The soluble fraction and the effective degradability of the crude protein were higher with urea. The effective degradability of the neutral detergent fiber of the two varieties was higher in the silages with NaOH and CaO. The silages treated with NaOH and CaO are the best in nutritional value, because of the highest effective degradability of dry matter and neutral detergent fiber. The IAC 86-2480 variety presents better nutritional value than RB 86-7515, due to the highest effective degradability of dry matter., Objetivou-se com este trabalho avaliar a degradabilidade in situ da matéria seca, proteína bruta e fibra em detergente neutro das silagens de variedades de cana-de-açúcar com aditivos. A avaliação da degradabilidade foi realizada segun- do um delineamento em blocos casualizados, em esquema fatorial 2 x 6 sendo duas variedades de cana (IAC 86-2480 e RB 86-7515), e cinco aditivos (ureia, NaOH, CaO, milho grão moído e Lactobacillus buchneri), mais a silagem-controle, com 3 blocos (animais). A fração solúvel e a degradabilidade efetiva da matéria seca das silagens com NaOH e CaO aumentaram. A fração solúvel e a de- gradabilidade efetiva da proteína bruta foram maiores nas silagens com ureia. A degradabilidade efetiva da fibra em detergente neutro das duas variedades foi maior nas silagens com NaOH e CaO. As silagens com NaOH e CaO são de melhor valor nutricional, pois apresentam maior de- gradabilidade efetiva da matéria seca e fibra em detergente neutro. A variedade IAC 86-2480 apresenta melhor valor nutricional em relação à RB 86-7515, devido à maior degradabilidade efetiva da matéria seca.

Published
2014

14. Composição química do bagaço de cana-de-açúcar amonizado com diferentes doses de uréia e soja grão

Author

Abreu, C.L, Bonalti, F.K.Q, Oliveira, T.S., Rocha Júnior, V.R., Reis, S.T., Aguiar, E.F., Souza, A.S., Silva, G. W. V., Dutra, E.S., Silva, C.J., Abreu, C.L, Bonalti, F.K.Q, Oliveira, T.S., Rocha Júnior, V.R., Reis, S.T., Aguiar, E.F., Souza, A.S., Silva, G. W. V., Dutra, E.S., and Silva, C.J.

Abstract

The objective of this work was to evaluate the effect of the different levels of urea and ground whole soybean as a urease source on the chemical composition of the ammoniated sugarcane bagasse. Four levels of urea (2%, 4%, 6% e 8% DM) and three levels of ground whole soybean (0%; 2% e 4%, DM) were added to sugarcane bagasse stored during 52 days in plastic bags (50 L). We analyzed the levels of DM, CP, NDF, ADF, cellulose, hemicellulose and lignin. Was used a complete randomized design with three replicates for treatments. The gradual increase of the urea levels in the process of amonização of sugarcane bagasse implied in reduction of NDF, ADF, cellulose, hemicellulose and lignin, and increase of CP. However, the levels of DM were not affected by different levals of urea and whole soybean used in different treatments, differing only in the DM of in nature sugarcane bagasse. The use of ground whole soybean, as source of urease, in the amonização of sugarcane bagasse, was efficient in the reduction of the levels of ND, Objetivou-se com este trabalho avaliar o efeito de diferentes doses de uréia e soja grão moída, como fonte de urease, sobre a composição quími- ca do bagaço de cana-de-açúcar amonizado. Utilizaram-se quatro doses de uréia (2, 4, 6 e 8% MS) e três doses de soja grão moída (0; 2 e 4% MS) no bagaço de cana-de-açúcar armazenado por um período de 52 dias, em sacos de polietileno com capacidade de 50 litros. Foram analisados os teores de MS, PB, FDN, FDA, hemicelulose, celulose e lignina. Foi utilizado delineamento experimental inteiramente casualizado com três repetições por tratamento. O aumento das doses de uréia no processo de amonização do bagaço de cana-de- açúcar implicou em redução dos teores de FDN, FDA, celulose, hemicelulose e lignina, e aumento dos teores de PB. Todavia, os teores de MS não foram afetados pelas diferentes doses de uréia e soja grão moída utilizadas nos tratamentos, diferindo apenas da MS do bagaço de cana in natura. A utilização da soja grão moída, como fonte de urease, na amonização do bagaço de cana-de-açúcar, foi eficiente na redução dos níveis de FDN apenas para as doses de 2 e 4% de uréia.

Published
2011

28. Synthesis and Characterization of Th2N2(NH) Isomorphous to Th2N3.

Author

Silva, G. W. Chinthaka, Yeamans, Charles B., Weck, Philppe F., Hunn, John D., Cerefice, Gary S., Sattelberger, Alfred P., and Czerwinski, Ken R.

Subjects
*FLUORIDES, *THORIUM, *IMIDES, *NITRIDES, *X-ray diffraction
Abstract

Using a new, low-temperature, fluoride-based process, thorium nitride imide of the chemical formula Th2N2(NH) was synthesized from thorium dioxide via an ammonium thorium fluoride intermediate. The resulting product phase was characterized by powder X-ray diffraction (XRD) analysis and was found to be crystallographically similar to Th2N3. Its unit cell was hexagonal with a space group of P3m̅1 and lattice parameters of a = b = 3.886(1) and c = 6.185(2) Å. The presence of -NH in the nitride phase was verified by Fourier transform infrared spectroscopy (FTIR). Total energy calculations performed using all-electron scalar relativistic density functional theory (DFT) showed that the hydrogen atom in the Th2N2(NH) prefers to bond with nitrogen atoms occupying 1a Wyckoff positions of the unit cell. Lattice fringe disruptions observed in nanoparticle areas of the nitride species by high-resolution transmission electron microscopic (HRTEM) images also displayed some evidence for the presence of -NH group. As ThO2 was identified as an impurity, possible reaction mechanisms involving its formation are discussed. [ABSTRACT FROM AUTHOR]

Published
2012
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30. Crystal and Electronic Structures of Neptunium Nitrides Synthesized Using a Fluoride Route.

Author

Chinthaka Silva, G. W., Weck, Philippe F., Kim, Eunja, Yeamans, Charles B., Cerefice, Gary S., Sattelberger, Alfred P., and Czerwinski, Kenneth R.

Subjects
*CRYOCHEMISTRY, *ELECTRONIC structure, *CRYSTAL structure research, *NEPTUNIUM, *NITRIDES, *CHEMISTRY methodology, *CHEMICAL synthesis, *FLUORIDES
Abstract

A low-temperature fluoride route was utilized to synthesize neptunium mononitride, NpN. Through the development of this process, two new neptunium nitride species, NpN2 and Np2N3, were identified. The NpN2 and Np2N3 have crystal structures isomorphous to those of UN2 and U2N3, respectively. NpN2 crystallizes in a face-centered cubic CaF2-type structure with a space group of Fm3m and a refined lattice parameter of 5.3236(1) Å. The Np2N3 adopts the body-centered cubic Mn2O3-type structure with a space group of Ia3. Its refined lattice parameter is 10.6513(4) Å. The NpN synthesis at temperatures ≤900 °C using the fluoride route discussed here was also demonstrated. Previous computational studies of the neptunium nitride system have focused exclusively on the NpN phase because no evidence was reported experimentally on the presence of NpNx systems. Here, the crystal structures of NpN2 and Np2N3 are discussed for the first time, confirming the experimental results by density functional calculations (DFT). These DFT calculations were performed within the local-density approximation (LDA+U) and the generalized-gradient approximation (GGA+U) corrected with an effective Hubbard parameter to account for the strong on-site Coulomb repulsion between Np 5f electrons. The effects of the spin-orbit coupling in the GGA+U calculations have also been investigated for NpN2 and NpN. [ABSTRACT FROM AUTHOR]

Published
2012
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31. Fluoride-Conversion Synthesis of Homogeneous Actinide Oxide Solid Solutions.

Author

Chinthaka Silva, G. W., Hunn, John D., Yeamans, Charles, Cerefice, Gary S., and Czerwinski, Ken R.

Subjects
*FLUORIDES, *ACTINIUM compounds, *SOLID solutions, *AMMONIUM bicarbonate, *NANOCHEMISTRY
Abstract

The synthesis of (U,Th)O2 solid solutions at a relatively low temperature of 1100 °C using a new technique is described. First, separate actinide oxides were reacted with ammonium hydrogen fluoride to form ammonium actinide fluorides at room temperature. Subsequently, this fluoride was converted to an actinide oxide solid solution using a two-phase reaction process, which involved heating of the fluoride first at 610 °C in static air followed by heating at 1100 °C in flowing argon. Oxide solid solutions of UO2 and ThO2 were synthesized for a ThO2 content from 10 to 90 wt %. Microscopic investigation showed that the (U,Th)O2 solid solutions synthesized using this method had high crystallinity and homogeneity up to nanoscale. [ABSTRACT FROM AUTHOR]

Published
2011
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32. Preparation of technetium metal by thermal treatment under argon/H2O.

Author

Poineau, F., Hartmann, T., Silva, G. W. Chinthaka, Jarvinen, G., and Czerwinski, K.

Subjects
TECHNETIUM, RADIOACTIVE substances, ARGON, SURFACE chemistry, SURFACE tension
Abstract

A new method for the preparation of Tc metal from pertechnetate is described. Metallic technetium was prepared from TcO by initial reduction in dry argon atmosphere at 300 °C followed by a wet argon atmosphere in the presence of carbon between 700 and 910 °C. The higher temperature conditions in the presence of H2O and carbon form H2 and CO, which can drive the reduction of TcO2. This method was applied to the recovery of pertechnetate sorbed on anion-exchange resins resulting in the formation of Tc metal microspheres. The resulting Tc was characterized by XRD analysis and SEM. [ABSTRACT FROM AUTHOR]

Published
2009
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