Synthesis of isoquinolines by irradiation of 1-methoxy-2-azabuta-1,3-dienes in a neutral medium

We describe, for the first time, the photocyclization of 2-azadienes in a neutral medium. The reaction leads to the formation of isoquinolines. © 2001 Elsevier Science Ltd. All rights reserved

Susceptibility of Ipomoea quamoclit, I. triloba and Merremia cissoides to the Herbicides Sulfentrazone and Amicarbazone

A suscetibilidade diferencial de espécies de plantas daninhas a herbicidas é uma importante variável que deve ser considerada na escolha do herbicida e dose a serem aplicados. Assim, dois experimentos foram desenvolvidos com o objetivo de avaliar a suscetibilidade de três espécies de plantas daninhas da família Convolvulaceae (Ipomoea quamoclit, I. triloba e Merremia cissoides) aos herbicidas sulfentrazone e amicarbazone, por meio de curvas de dose-resposta. Os experimentos foram instalados em área com solo argiloso, onde foram aplicadas oito doses de cada herbicida, em pré-emergência. As doses utilizadas foram 8D, 4D, 2D, D, 1/2D, 1/4D, 1/8D e testemunha sem aplicação, sendo D a dose recomendada de sulfentrazone (600 g ha-1) ou de amicarbazone (980 g ha-1). As doses recomendadas de ambos os herbicidas foram eficazes para controlar as três plantas daninhas nas avaliações realizadas até os 60 dias após aplicação. Observou-se suscetibilidade diferencial entre as espécies estudadas, em que I. quamoclit foi a mais sensível. As ordens de suscetibilidade das espécies aos herbicidas foram: I. quamoclit > M. cissoides > I. triloba para o sulfentrazone; e I. quamoclit > I. triloba > M. cissoides para o amicarbazone. Os níveis de controle indicam a viabilidade de aplicação de sulfentrazone e amicarbazone em pré-emergência para controle dessas espécies de plantas daninhas da família Convolvulaceae.Differential susceptibility of weed species to herbicides is an important variable that must be considered when choosing the herbicide and rate to be applied. Thus, two experiments were carried out with the objective of evaluating the susceptibility of three weed species of the Convolvulaceae family (Ipomoea quamoclit, I. triloba and Merremia cissoides) to the herbicides sulfentrazone and amicarbazone, using dose-response curves. Trials were installed in an area with clay soil, where eight rates of each herbicide were applied, in pre-emergence. The herbicide rates were: 8D, 4D, 2D, D, 1/2D, 1/4D, 1/8D and check without application, considering D as the recommended rate for sulfentrazone (600 g ha-1) or amicarbazone (980 g ha-1). Recommended rates of both herbicides were effective to control the three weed species, in the evaluations performed up to 60 days after application. Differential susceptibility of weed species to herbicides was observed, characterizing I. quamoclit as the most sensitive species. The susceptibility scales were: I. quamoclit > M. cissoides > I. triloba for sulfentrazone; and I. quamoclit > I. triloba > M. cissoides for amicarbazone. Control levels indicate that application of sulfentrazone and amicarbazone in pre-emergence is viable to control these weed species of Convolvulaceae

Calculation Of The Giant Magnetocaloric Effect In The Mnfep 0.45as0.55 Compound

We report the theoretical investigations on the giant magnetocaloric compound MnFeP0.45As0.55. The magnetic state equation used takes into account the magnetoelastic effect that leads the magnetic system to order under first order paramagnetic-ferromagnetic phase transition. The model parameters were determined from the magnetization data adjustment and used to calculate the magnetocaloric thermodynamic quantities. The theoretical calculations are compared with the available experimental data.709944101-094410-5Yu, B.F., Gao, Q., Zhang, B., Mang, X.Z., Chen, Z., (2003) Int. J. Refrig., 26, p. 622Gschneidner Jr., K.A., Pecharsky, V.K., (1997) Rare Earths: Science, Technology and Application III, , edited by R. C. Bautista, C. O. Bounds, T. W. Ellis, and B. T. Kilbourn The Minerals, Metals & Materials Society, WarendaleBrown, G.V., (1976) J. Appl. Phys., 47, p. 3673Pecharsky, V.K., Gschneidner Jr., K.A., (1997) Phys. Rev. Lett., 78, p. 4494Tegus, O., Brück, E., Buschow, K.H.J., De Boer, F.R., (2002) Nature, 415, p. 150. , LondonMorellon, L., Algarabel, P.A., Ibarra, M.R., Blasco, J., García-Landa, B., Arnold, Z., Albertini, F., (1998) Phys. Rev. B, 58, pp. R14721Rodbell, D.S., (1961) Phys. Rev. Lett., 7, p. 1Bean, C.P., Rodbell, D.S., (1961) Phys. Rev., 126, p. 104Bacmann, M., Soubeyroux, J.-L., Barrett, R., Fruchart, D., Zach, R., Niziol, S., Fruchart, R., (1983) J. Magn. Magn. Mater., 134, p. 59Brück, E., Tegus, O., Li, X.W., Deboer, F.R., Buschow, K.H.J., (2003) Physica B, 327, p. 431Tegus, O., Brück, E., Zhang, L., Dagula, Buschow, K.H.J., De Boer, F.R., (2002) Physica B, 319, p. 174Zach, R., Guillot, M., Tobola, J., (1998) J. Appl. Phys., 83, p. 7237Tegus, O., (2003) Novel Materials for Magnetic Refrigeration, , PhD thesis, Van der Waals-Zeeman Instituut, Universiteit van Amsterdam, Printer Partners Ipskamp B. V., ISBN: 9057761076, OctoberVon Ranke, P.J., Grangeia, D.F., Caldas, A., De Oliveira, N.A., (2003) J. Appl. Phys., 93, p. 4055Wada, H., Tanabe, Y., (2001) Appl. Phys. Lett., 79, p. 3302Wada, H., Morikawa, T., Taniguchi, K., Shibata, T., Yamada, Y., Akishige, Y., (2003) Physica B, 328, p. 11

Energy relaxation of an excited electron gas in quantum wires: many-body electron LO-phonon coupling

We theoretically study energy relaxation via LO-phonon emission in an excited one-dimensional electron gas confined in a GaAs quantum wire structure. We find that the inclusion of phonon renormalization effects in the theory extends the LO-phonon dominated loss regime down to substantially lower temperatures. We show that a simple plasmon-pole approximation works well for this problem, and discuss implications of our results for low temperature electron heating experiments in quantum wires.Comment: 10 pages, RevTex, 4 figures included. Also available at http://www-cmg.physics.umd.edu/~lzheng

Simple Dynamics on the Brane

We apply methods of dynamical systems to study the behaviour of the Randall-Sundrum models. We determine evolutionary paths for all possible initial conditions in a 2-dimensional phase space and we investigate the set of accelerated models. The simplicity of our formulation in comparison to some earlier studies is expressed in the following: our dynamical system is a 2-dimensional Hamiltonian system, and what is more advantageous, it is free from the degeneracy of critical points so that the system is structurally stable. The phase plane analysis of Randall-Sundrum models with isotropic Friedmann geometry clearly shows that qualitatively we deal with the same types of evolution as in general relativity, although quantitatively there are important differences.Comment: an improved version, 34 pages, 9 eps figure

Influence of phenolic acids on growth and inactivation of Oenococcus oeni and Lactobacillus hilgardii

Aims: To determine the effect of several wine-associated, phenolic acids on the growth and viability of strains of Oenococcus oeni and Lactobacillus hilgardii. Methods and Results: Growth was monitored in ethanol-containing medium supplemented with varying concentrations of hydroxybenzoic acids (p-hydroxybenzoic, protocatechuic, gallic, vanillic and syringic acids) and hydroxycinnamic acids (p-coumaric, caffeic and ferulic acids). Progressive inactivation was monitored in ethanolcontaining phosphate buffer supplemented in a similar manner to the growth experiments. Hydroxycinnamic acids proved to be more inhibitory to the growth of O. oeni than hydroxybenzoic acids. On the other hand, some acids showed a beneficial effect on growth of Lact. hilgardii. p-Coumaric acid showed the strongest inhibitory effect on growth and survival of both bacteria. Conclusions: Most phenolic acids had a negative effect on growth of O. oeni, for Lact. hilgardii this effect was only noted for p-coumaric acid. Generally, O. oeni was more sensitive to phenolic acid inactivation than Lact. hilgardii. Significance and Impact of the Study: Eight wine-derived, phenolic acids were compared for their effects on wine lactic acid bacteria. Results indicate that phenolic acids have the capacity to influence growth and survival parameters. The differences found between phenolic compounds could be related to their different chemical structures

The Magnetic And Magnetocaloric Properties Of Gd 5ge 2si 2 Compound Under Hydrostatic Pressure

The Gd5 Ge2 Si2 compound presents a giant magnetocaloric effect with transition temperature at around 276 K and is a very good candidate for application as an active regenerator material in room temperature magnetic refrigerators. Recently it has been shown that pressure induces a colossal magnetocaloric effect in MnAs, a material that presents a giant magnetocaloric effect and a strong magnetoelastic coupling, as also happens with the Gd5 Ge2 Si2 compound. This motivated a search of the colossal effect in the Gd5 Ge2 Si2 compound. This work reports our measurements on the magnetic properties and the magnetocaloric effect of Gd5 Ge2 Si2 under hydrostatic pressures up to 9.2 kbar and as a function of temperature. Contrary to what happens with MnAs, pressure increases the Curie temperature of the compound, does not affect the saturation magnetization and decreases markedly its magnetocaloric effect. © 2005 American Institute of Physics.9710Pecharsky, V.K., Gschneidner Jr., K.A., (1977) Phys. Rev. Lett., 78, p. 4494Pecharsky, V.K., Gschneidner Jr., K.A., (2001) Adv. Mater. (Weinheim, Ger.), 13, p. 683Morellon, L., Algarabel, P.A., Ibarra, M.R., Blasco, J., García-Landa, B., Arnold, Z., Albertini, F., (1998) Phys. Rev. B, 58, p. 14721Del Moral, A., Algarabel, P.A., Arnaudas, J.I., Benito, L., Ciria, M., De La Fuente, C., García-Landa, B., De Teresa, J.M., (2002) J. Magn. Magn. Mater., 242-245, p. 788Pecharsky, A.O., Gschneidner Jr., K.A., Pecharsky, V.K., (2003) J. Magn. Magn. Mater., 267, p. 60Pecharsky, A.O., Gschneidner Jr., K.A., Pecharsky, V.K., (2003) J. Appl. Phys., 93, p. 4722Gama, S., De Campos, A., Carvalho Magnus, A.G., Coelho, A.A., Gandra, F.C.G., Von Ranke, P.J., De Oliveira, N.A., (2004) Phys. Rev. Lett., 93, p. 237202Von Ranke, P.J., De Oliveira, N.A., Gama, S., (2004) J. Magn. Magn. Mater., 277, p. 78Pecharsky, V.K., Gschneidner Jr., K.A., (1998) Adv. Cryog. Eng., 43, p. 1729Menyuk, N., Kafalas, J.A., Dwight, K., Goodenough, J.B., (1969) Phys. Rev., 177, p. 942Morellon, L., Arnold, Z., Algarabel, P.A., Magen, C., Ibarra, M.R., Skorodhod, Y., (2004) J. Phys.: Condens. Matter, 16, p. 162