908 research outputs found
Static and dynamic Jahn-Teller effect in the alkali metal fulleride salts A4C60 (A = K, Rb, Cs)
We report the temperature dependent mid- and near-infrared spectra of K4C60,
Rb4C60 and Cs4C60. The splitting of the vibrational and electronic transitions
indicates a molecular symmetry change of C604- which brings the fulleride anion
from D2h to either a D3d or a D5d distortion. In contrast to Cs4C60, low
temperature neutron diffraction measurements did not reveal a structural phase
transition in either K4C60 and Rb4C60. This proves that the molecular
transition is driven by the molecular Jahn-Teller effect, which overrides the
distorting potential field of the surrounding cations at high temperature. In
K4C60 and Rb4C60 we suggest a transition from a static to a dynamic Jahn-Teller
state without changing the average structure. We studied the librations of
these two fullerides by temperature dependent inelastic neutron scattering and
conclude that both pseudorotation and jump reorientation are present in the
dynamic Jahn-Teller state.Comment: 13 pages, 10 figures, to be published in Phys. Rev.
IdentificaĆ§Ć£o de carotenoides em polpa de goiaba microencapsulada utilizando cromatografia lĆquida de alta eficiĆŖncia.
TĆtulo: goaiba [i.e. goiaba]
Production of grape juice powder obtained by freeze-drying after concentration by reverse osmosis.
This study aimed to evaluate the freeze-drying process for obtaining grape juice powder by reverse osmosis using 50% grape juice pre-concentrated (28.5 Ā°Brix) and 50% hydrocolloids (37.5% maltodextrin and 12.5% arabic gum)
Melhoramento genĆ©tico e produĆ§Ć£o de rainhas de Apis mellifera.
bitstream/item/87876/1/MELHORAMENTO-GENETICO.pd
Gapped Excitations in the High-Pressure Antiferromagnetic Phase of URuSi
We report a neutron scattering study of the magnetic excitation spectrum in
each of the three temperature and pressure driven phases of URuSi. We
find qualitatively similar excitations throughout the (H0L) scattering plane in
the hidden order and large moment phases, with no changes in the
-widths of the excitations at the = (1.407,0,0) and =
(1,0,0) points, within our experimental resolution. There is, however, an
increase in the gap at the point from 4.2(2) meV to 5.5(3) meV,
consistent with other indicators of enhanced antiferromagnetism under pressure.Comment: 5 pages, 3 figures, 1 tabl
AvaliaĆ§Ć£o fisiolĆ³gica de sementes de mogno brasileiro (Swietenia macrophylla King.) em diferentes temperaturas e substratos.
Este trabalho teve como objetivo determinar as caracterĆsticas biomĆ©tricas de frutos e sementes, e o efeito da temperatura e substrato na germinaĆ§Ć£o de sementes de mogno brasileiro. A mensuraĆ§Ć£o foi realizada com auxilio de paquĆmetro digital, e para o teste de germinaĆ§Ć£o foi utilizado germinador com temperaturas constantes de 25Ā°C e 30Ā°C, e como substratos o papel toalha, a vermiculita, areia e areia+serragem. O delineamento experimental utilizado foi inteiramente casualizado com esquema fatorial 2x4 (temperaturas x substratos, respectivamente), com 4 repetiƧƵes e 25 sementes por parcela. Os resultados absolutos de contagem de germinaĆ§Ć£o foram transformados em percentagem, logo apĆ³s, transformados em arco seno (x/100)1/2 para normalizaĆ§Ć£o da distribuiĆ§Ć£o. No tratamento areia+serragem, nas condiƧƵes de temperaturas constantes iguais a 25Āŗ e 30Āŗ C os percentuais de germinaĆ§Ć£o foram superiores
Viabilidade de sementes de paricĆ” (Schizolobium parahyba var. amazonicum (Huber x Ducke) Barneby) pelo teste de tetrazĆ³lio.
bitstream/item/50184/1/fd340001.pdf1 folder
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