Pressure effect on vibrational frequency and dephasing of 1-alkyl-3-methylimidazolium hexafluorophosphate ionic liquids.

Raman spectra in the range of the totally symmetric stretching mode of the [PF6](-) anion, νs(PF6), have been measured for 1-alkyl-3-methylimidazolium ionic liquids [CnC1im][PF6], for n = 4, 6, and 8, as a function of pressure at room temperature. The ionic liquids [C6C1im][PF6] and [C8C1im][PF6] remain in an amorphous phase up to 3.5 GPa, in contrast to [C4C1im][PF6], which crystallizes above ~0.5 GPa. Equations of state based either on a group contribution model or Carnahan-Starling-van der Waals model have been used to estimate the densities of the ionic liquids at high pressures. The shifts of the vibrational frequency of νs(PF6) with density observed in [C6C1im][PF6] and in [C8C1im][PF6] have been calculated by a hard-sphere model of a pseudo-diatomic solute under short-range repulsive interactions with the neighboring particles. The stochastic model of Kubo for vibrational dephasing has been used to obtain the amplitude of vibrational frequency fluctuation, <Δω(2)>, and the relaxation time of frequency fluctuation, τc, as a function of density by Raman band shape analysis of the νs(PF6) mode of [C6C1im][PF6] and [C8C1im][PF6].

Desponte e embebição em sementes de noni (Morinda citrifolia L. ) / Lopping and soaking in seeds of noni (Morinda citrifolia L. )

O trabalho teve como objetivo testar a germinação em sementes de noni sob diferentes tempos de embebição, com e sem o desponte das sementes. Para isso, instalou-se um experimento em casa de vegetação no delineamento inteiramente casualizado com 10 tratamentos e 4 repetições de 25 sementes , sendo constituídos por: 1. Testemunha; 2. Sementes com desponte do lado oposto ao embrião; 3. Sementes intactas com 12 horas de embebição; 4. Sementes intactas com 24 horas de embebição; 5. Sementes intactas com 36 horas de embebição; 6. Sementes intactas com 48 horas de embebição; 7. Sementes com desponte com 12 horas de embebição; 8. Sementes com desponte com 24 horas de embebição; 9. Sementes com desponte com 36 horas de embebição e 10. Sementes com desponte com 48 horas de embebição. As características avaliadas foram: porcentagem de emergência, Índice de velocidade de emergência, altura de plântulas, comprimento de raiz e peso de massa seca das plântulas aos 46 dias após a instalação do experimento. Houve diferença significativa entre os diferentes tempos de embebição e o tratamento 10 (Desponte com 48 hs de embebição) que obteve os melhores resultados para a percentagem de emergência, índice e velocidade de emergência e peso seco. Quanto a altura de plântula, o tratamento 1 (Testemunha) foi o maior, enquanto no tratamento 2 (desponte) se verificou o maior comprimento de raiz. Embora não tenha diferido da testemunha, o melhor tratamento foi o uso do desponte + 48 horas de embebição.

The study aimed to test the germination of seeds of noni under different soaking times, with and without the seed emerges. For this, an experiment was installed in a greenhouse in a completely randomized design with 10 treatments and 4 replicates of 25 seeds, being composed of: 1. Witness 2. Seeds with the blunt side opposite the embryo 3. Intact seeds with 12 hours of soaking, 4. Intact seeds with 24 hours of soaking, 5. Intact seeds with 36 hours of soaking, 6. Intact seeds with 48 hours of soaking; 7. Seeds with cutting with 12 hours of soaking; 8. Seeds with cutting with 24 hours of soaking; 9. Seeds with cutting with 36 hours of soaking and 10. Seeds with cutting with 48 hours of soaking. The characteristics evaluated were: percentage of emergence, speed of emergence index, seedling height, root length and weight of the dry mass of seedlings 46 days after the experiment. There were significant differences between the different times of soaking and treatment 10 (cutting with 48 hours of soaking) who obtained the best results for the percentage of emergency and emergency speed index and dry weight. The height of the seedling, one treatment (control) was the highest, while in treatment 2 (blunt) registered the largest root length. Although the witness did not differ, the best treatment was the use of blunt + 48 hours of soaking.