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| 12. |  | NOVOTNY, E. H.; KNICKER, H.; MARTIN NETO, L.; AZEREDO, R. B. V.; HAYES, M. H. B. Effect of residual vanadyl ions on the spectroscopic analysis of humic acids: a multivariate approach. European Journal of Soil Science, Oxford, v. 59, n. 3, p. 439-444, Jun. 2008.| Biblioteca(s): Embrapa Solos. |
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| 16. | | VENÂNCIO, T.; ENGELSBERG, M.; AZEREDO, R. B. V. de; ALEM, N. E. R.; COLNAGO, L. A. CWFP as a tool for fast and simultaneous measurement of T1 and T2 relaxation times. In: NUCLEAR MAGNETIC RESONANCE USERS MEETING, 10th; PORTUGUESE-BRAZILIAN NMR MEETING, 3rd; IBEROAMERICAN NMR MEETING, 1st., 2005, Angra dos Reis. Anais... Rio de Janeiro: Associação de Usuários de Ressonância Magnética nuclear - AUREMN, 2005. não paginado.| Biblioteca(s): Embrapa Instrumentação. |
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| Registros recuperados : 31 | |
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 | Acesso ao texto completo restrito à biblioteca da Embrapa Instrumentação. Para informações adicionais entre em contato com cnpdia.biblioteca@embrapa.br. |
Registro Completo
|
Biblioteca(s): |
Embrapa Instrumentação. |
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Data corrente: |
25/08/2005 |
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Data da última atualização: |
25/08/2005 |
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Autoria: |
AZEREDO, R. B. V.; ENGELSBERG, M.; COLNAGO, L. A. |
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Título: |
Flow sensitivity and coherence in steady-state freee spin procession. |
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Ano de publicação: |
2001 |
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Fonte/Imprenta: |
Physical Review E., New York, v. 64, n. 1/2, p. 016309-1 a 016309-4, 2001. |
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Idioma: |
Inglês |
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Conteúdo: |
Steady-state free precession (SSFP) of nuclear spins in the presence of a magnetic field gradient is known to be very sensitive to flow. We present a theoretical and experimental study of flow sensitivity in a regime where the spacing of the radio-frequency pulses is extremely short compared with the free induction decay time and the relaxation times. Under these rather drastic conditions, a truly continuous wave freee precession (CWFP) regime is establisehd, in which, unlike standard SSFP, a large degree of coherence is preserved. This leads to a quite different flow sensitivity, which is significant even when very small magnetic field gradients are present. The unspoiled coherence is predicted to cause different flow effects which we confirmed experimentally. Toilored flow sensitivity can be achieved by adjusting the frequency offset from resonance, which plays a dominant role in the CWFP regime. |
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Palavras-Chave: |
SSFP. |
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Thesagro: |
Física. |
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Categoria do assunto: |
-- |
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Marc: |
LEADER 01389naa a2200169 a 4500
001 1029013
005 2005-08-25
008 2001 bl --- 0-- u #d
100 1 $aAZEREDO, R. B. V.
245 $aFlow sensitivity and coherence in steady-state freee spin procession.
260 $c2001
520 $aSteady-state free precession (SSFP) of nuclear spins in the presence of a magnetic field gradient is known to be very sensitive to flow. We present a theoretical and experimental study of flow sensitivity in a regime where the spacing of the radio-frequency pulses is extremely short compared with the free induction decay time and the relaxation times. Under these rather drastic conditions, a truly continuous wave freee precession (CWFP) regime is establisehd, in which, unlike standard SSFP, a large degree of coherence is preserved. This leads to a quite different flow sensitivity, which is significant even when very small magnetic field gradients are present. The unspoiled coherence is predicted to cause different flow effects which we confirmed experimentally. Toilored flow sensitivity can be achieved by adjusting the frequency offset from resonance, which plays a dominant role in the CWFP regime.
650 $aFísica
653 $aSSFP
700 1 $aENGELSBERG, M.
700 1 $aCOLNAGO, L. A.
773 $tPhysical Review E., New York$gv. 64, n. 1/2, p. 016309-1 a 016309-4, 2001.
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