Germination of small bengal dayflower (Commelina benghalensis) aerial seeds

O conhecimento científico sobre a biologia de plantas daninhas relacionado ao fluxo de emergência das plântulas, às causas de dormência das sementes e à profundidade máxima de emergência contribui significativamente para a utilização de estratégias racionais de manejo dessas plantas na agricultura. Assim, este trabalho foi desenvolvido com o objetivo de avaliar a germinação de sementes e a emergência da plântula de sementes aéreas pequenas de trapoeraba (Commelina benghalensis). Para isso, as sementes foram submetidas à superação de dormência em solução de ácido sulfúrico (por períodos de 1, 2, 3, 4 e 5 minutos), em diferentes condições de temperaturas (temperaturas médias de 16,1; 18,6; 20,6; 23,1; 25,0; 26,9; 29,2; 31,1; e 33,6 ºC), de luz (com e sem) e de profundidade de semeadura (0, 5, 10, 20, 40 e 80 mm). A temperatura ótima para germinação da trapoeraba foi de 25 ºC. Não houve efeito da luz na germinação das sementes. Não se observou interferência positiva na germinação por consequência do tratamento das sementes com ácido sulfúrico, em diferentes períodos de exposição, indicando que as sementes de trapoeraba não possuem impermeabilidade do tegumento à água. A emergência das plântulas de trapoeraba é influenciada negativamente e de forma linear pela profundidade de semeadura dos propágulos no substrato. Não houve emergência das plântulas quando as sementes foram depositadas a 80 mm de profundidade. O substrato areia favorece a emergência das plântulas.Understanding basic information on weed biology related to plant emergence fluxes, seed dormancy causes and maximum depth for emergence may significantly contribute to creating rational strategies for weed management in agriculture. Thus, this work was developed to evaluate seed germination and seedling emergence of small aerial seeds of Bengal dayflower (Commelina benghalensis).Seeds were submitted to dormancy overcoming in sulfuric acid (periods of 1, 2, 3, 5 and 5 minutes) under different conditions of temperature (mean temperatures of 16.1; 18.6; 20.6; 23.1; 25.0; 26.9; 29.2; 31.1 and 33.6ºC), light (with or without), and seeding depth in the substrate (0, 5, 10, 20, 40 and 80 mm). The optimal temperature for Bengal dayflower germination was 25ºC. Light effects were not observed on seed germination. Positive consequences of seed treatment with sulfuric acid were not identified, considering different periods of exposure; indicating that Bengal dayflower seeds do not have tegument water impermeability. Seedling emergence is negative and linearly influenced by seeding depth in the substrate. Seedling emergence was not observed when seeds were 80 mm depth placed. Sand substrate favored seedling emergence.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

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

Alternative herbicides to control glyphosate-resistant biotypes of Conyza bonariensis and C. canadensis

Após sucessivos anos, aplicações do herbicida glyphosate em pomares de citros no Estado de São Paulo selecionaram biótipos resistentes de Conyza bonariensis e C. canadensis. Na ocorrência de plantas daninhas resistentes em uma área agrícola, tornam-se necessárias mudanças nas práticas de manejo para obtenção de adequado controle das populações resistentes, bem como para a redução da pressão de seleção sobre outras espécies. Assim, este trabalho foi realizado com o objetivo de identificar herbicidas alternativos para controle de biótipos de Conyza spp. resistentes ao herbicida glyphosate, com aplicações em diferentes estádios fenológicos da planta daninha. Três experimentos foram conduzidos em campo, em pomares de citros em formação, sobre plantas de buva em estádio fenológico de dez folhas e no pré-florescimento. Para plantas no estádio de dez folhas, controle satisfatório foi obtido com aplicações de glyphosate + bromacil + diuron (1.440 + 1.200 + 1.200 g ha-1), glyphosate + atrazina (1.440 + 1.500 g ha-1) e glyphosate + diuron (1.440 + 1.500 g ha-1). Quando em estádio de pré-florescimento de Conyza spp., a aplicação do herbicida amônio-glufosinato, na dose de 400 g ha-1, isolado ou associado a MSMA, bromacil+diuron, metsulfuron, carfentrazone e paraquat, foi a alternativa viável para controle dos biótipos resistentes ao glyphosate.After successive years, glyphosate applications on São Paulo-Brazil citrus orchards selected resistant biotypes of Conyza bonariensis and C. canadensis. The occurrence of herbicide-resistant weed biotypes at some agricultural area makes it necessary to change the management practices to reach effective control of the selected resistant populations, as well as to reduce selection pressure on the other species. Thus, this work aimed to identify the alternative herbicides to control glyphosate-resistant biotypes of Conyza spp., with applications at different weed phenological stages. Three trials were developed under field conditions: in citrus orchards under formation, in plants with phenological stages of ten leaves and at pre-flowering. For plants at the ten leaf stage, satisfactory control was reached with applications of glyphosate + bromacil + diuron (1,440 + 1,200 + 1,200 g ha-1), glyphosate + atrazine (1,440 + 1,500 g ha-1) and glyphosate + diuron (1,440 + 1,500 g ha-1). For Conyza spp. plants at the pre-flowering stage, ammonium-glufosinate application, at the rate of 400 g ha-1, isolated or associated to MSMA, bromacil+diuron, metsulfuron, carfentrazone and paraquat, was a viable alternative to control glyphosate-resistant biotypes.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Isothermal Variation Of The Entropy (Δ St) For The Compound Gd5 Ge4 Under Hydrostatic Pressure

In the present work, the isothermal variation of the entropy (Δ ST) for the compound Gd5 Ge4 was studied at different applied hydrostatic pressures (from 0 up to 0.58 GPa). In all pressure ranges, we observe the giant magnetocaloric effect. The Δ ST data for the compound Gd5 Ge4 at zero applied pressure present two peaks: the lowest temperature peak is due to irreversible processes and the highest temperature peak is due to magnetostructural transitions. Increasing the pressure, the lowest temperature peak displaces to lower temperatures and disappears. The magnitude of the other peak has a nonlinear behavior with pressure. Different protocols were used to obtain Δ ST at zero applied pressure and the results indicate that Δ ST strongly depends on the initial and final states of Gd5 Ge4 compound. We also present a T-P magnetic phase diagram built from the available magnetic data. © 2008 American Institute of Physics.1046Pecharsky, V.K., Gschneidner Jr., K.A., (1999) J. Magn. Magn. Mater., 200, p. 44. , 0304-8853 10.1016/S0304-8853(99)00397-2Tishin, A.M., Spichkin, Y.I., (2003) The Magnetocaloric Effect and Its Applications, , (IOP, Bristol)Pecharsky, V.K., Gschneidner Jr., K.A., (1997) Phys. Rev. Lett., 78, p. 4494. , 0031-9007 10.1103/PhysRevLett.78.4494Magen, C., Arnold, Z., Morellon, L., Skorokhod, Y., Algarabel, P.A., Ibarra, M.R., Kamarad, J., (2003) Phys. Rev. Lett., 91, p. 207202. , 0031-9007 10.1103/PhysRevLett.91.207202Levin, E.M., Gschneidner Jr., K.A., Pecharsky, V.K., (2002) Phys. Rev. B, 65, p. 214427. , 0163-1829 10.1103/PhysRevB.65.214427Levin, E.M., Pecharsky, V.K., Gschneidner Jr., K.A., Miller, G.J., (2001) Phys. Rev. B, 64, p. 235103. , 0163-1829 10.1103/PhysRevB.64.235103Tang, H., Pecharsky, V.K., Gschneidner Jr., K.A., (2004) Phys. Rev. B, 69, p. 064410. , 0163-1829 10.1103/PhysRevB.69.064410Chattopadhyay, M.K., Manekar, M.A., Pecharsky, A.O., Pecharsky, V.K., Gschneidner Jr., K.A., Moore, J., Perkins, G.K., Cohen, L.F., (2004) Phys. Rev. B, 70, p. 214421. , 0163-1829 10.1103/PhysRevB.70.214421Mudryk, Ya., Holm, A.P., Gschneidner Jr., K.A., Pecharsky, V.K., (2005) Phys. Rev. B, 72, p. 064442. , 0163-1829 10.1103/PhysRevB.72.064442Levin, E.M., Gschneidner Jr., K.A., Lograsso, T.A., Schlagel, D.L., Pecharsky, V.K., (2004) Phys. Rev. B, 69, p. 144428. , 0163-1829 10.1103/PhysRevB.69.144428Pecharsky, V.K., Gschneidner Jr., K.A., (1997) Appl. Phys. Lett., 70, p. 3299. , 0003-6951 10.1063/1.119206Nikitin, S.A., Myalikgulyev, G., Tishin, A.M., Annaorazov, M.P., Asatryan, K.A., Tyurin, A.L., (1990) Phys. Lett. A, 148, p. 363. , 0375-9601 10.1016/0375-9601(90)90819-APecharsky, V.K., Gschneidner Jr., K.A., (1999) J. Appl. Phys., 86, p. 565. , 0021-8979 10.1063/1.370767Carvalho, A.M.G., (2006), Ph.D. thesis, UNICAMPCarvalho, A.M.G., Alves, C.S., De Campos, A., Coelho, A.A., Gama, S., Gandra, F.C.G., Von Ranke, P.J., De Oliveira, N.A., (2005) J. Appl. Phys., 97, pp. 10M320. , 0021-8979 10.1063/1.1860932Gschneidner Jr., K.A., Pecharsky, V.K., (2000) Annu. Rev. Mater. Sci., 30, p. 387. , 0084-6600 10.1146/annurev.matsci.30.1.387Carvalho, A.M.G., Alves, C.S., Colucci, C.C., Bolanho, M.A., Coelho, A.A., Gama, S., Nascimento, F.C., Cardoso, L.P., (2007) J. Alloys Compd., 432, p. 11. , 0925-8388 10.1016/j.jallcom.2006.05.121Wood, M.E., Potter, W.H., (1985) Cryogenics, 25, p. 667. , 0011-2275 10.1016/0011-2275(85)90187-0Magnus, A., Carvalho, G., Coelho, A.A., Gama, S., Von Ranke, P.J., De Oliveira, N.A., Da Silva, L.M., Gandra, F.C.G., (submitted

Theoretical Investigation On The Existence Of Inverse And Direct Magnetocaloric Effect In Perovskite Euzro 3

We report on the magnetic and magnetocaloric effect calculations in antiferromagnetic perovskite-type EuZrO 3. The theoretical investigation was carried out using a model Hamiltonian including the exchange interactions between nearest-neighbor and next-nearest-neighbor for the antiferromagnetic ideal G-type structure (the tolerance factor for EuZrO 3 is t = 0.983, which characterizes a small deformation from an ideal cubic perovskite). The molecular field approximation and Monte Carlo simulation were considered and compared. The calculated magnetic susceptibility is in good agreement with the available experimental data. For a magnetic field change from zero to 2 T a normal magnetocaloric effect was calculated and for a magnetic field change from zero to 1 T, an inverse magnetocaloric effect was predicted to occur below T = 3.6 K. © 2011 American Institute of Physics.1098Warburg, E., (1881) Ann. Phys., 13, p. 141. , 10.1002/andv249:5Pecharsky, V.K., Gschneidner Jr., K.A., (1997) Phys. Rev. Lett., 78, p. 4494. , 10.1103/PhysRevLett.78.4494Von Ranke, P.J., De Oliveira, N.A., Gama, S., (2004) J. Magn. Magn. Mater., 277, p. 78. , 10.1016/j.jmmm.2003.10.013De Oliveira, N.A., Von Ranke, P.J., (2008) Phys. Rev. B, 77, p. 214439. , 10.1103/PhysRevB.77.214439Von Ranke, P.J., De Oliveira, N.A., Plaza, E.J.R., De Sousa, V.S.R., Alho, B.P., Magnus, A., Carvalho, G., Reis, M.S., (2008) J. Appl. Phys., 104, p. 093906. , 10.1063/1.3009974Sande, P., Hueso, L.E., Miguens, D.R., Rivas, J., Rivadulla, F., Lopez-Quintela, M.A., (2001) Appl. Phys. Lett., 79, p. 2040. , 10.1063/1.1403317Yamada, H., Goto, T., (2004) Physica B, 346-347, p. 104. , 10.1016/j.physb.2004.01.029Nobrega, E.P., De Oliveira, N.A., Von Ranke, P.J., Troper, A., (2006) Phys. Rev. B, 74, p. 144429. , 10.1103/PhysRevB.74.144429Tishin, A.M., Spichkin, Y.I., (2003) The Magnetocaloric Effect and Its Applications, , 1st ed. (Institute of Physics, Bristol)De Oliveira, N.A., Von Ranke, P.J., (2010) Phys. Rep., 489, p. 89. , 10.1016/j.physre2009.12.006Sasaki, S., Prewitt, C.T., Liebermann, R.C., (1983) Am. Mineral., 68, p. 1189Kuz'Min, M.D., Tishin, A.M., (1991) J. Phys. D: Appl. Phys., 24, p. 2039. , 10.1088/0022-3727/24/11/020Kimura, H., Numazawa, T., Sato, M., Ikeya, T., Fukuda, T., (1995) J. Appl. Phys., 77, p. 432. , 10.1063/1.359349Phan, M.-H., Yu, S.-C., Review of the magnetocaloric effect in manganite materials (2007) Journal of Magnetism and Magnetic Materials, 308 (2), pp. 325-340. , DOI 10.1016/j.jmmm.2006.07.025, PII S0304885306009577Zong, Y., Fujita, K., Akamatsu, H., Murai, S., Tanaka, K., (2010) J. Solid State Chem., 183, p. 168. , 10.1016/j.jssc.2009.10.014Kolodiazhnyi, T., Fujita, K., Wang, L., Zong, Y., Tanaka, K., Sakka, Y., Takayama-Muromachi, E., (2010) Appl. Phys. Lett., 96, p. 252901. , 10.1063/1.3456730Greedan, J.E., Chien, C.-L., Johnston, R.G., (1976) J. Solid State Chem., 19, p. 155. , 10.1016/0022-4596(76)90163-8Nobrega, E.P., De Oliveira, N.A., Von Ranke, P.J., Troper, A., Monte Carlo calculations of the magnetocaloric effect in Gd5(SixGe1-x)4 compounds (2005) Physical Review B - Condensed Matter and Materials Physics, 72 (13), pp. 1-7. , http://oai.aps.org/oai/?verb=ListRecords&metadataPrefix= oai_apsmeta_2&set=journal:PRB:72, DOI 10.1103/PhysRevB.72.134426, 134426Nbrega, E.P., De Oliveira, N.A., Von Ranke, P.J., Troper, A., (2008) J. Magn. Magn. Mater., 320, p. 147. , 10.1016/j.jmmm.2008.02.036Landau, D.P., Binder, K., (2000) A Guide to Monte Carlo Simulations in Statistical Physics, , (Cambridge University Press, Cambridge)Yang, H., Ohishi, Y., Kurosaki, K., Muta, H., Yamanaka, S., (2010) J. Alloys Compd., 504, p. 201. , 10.1016/j.jallcom.2010.05.088Terki, R., Bertrand, G., Aourag, H., Coddet, C., Thermal properties of Ba 1-xSr xZrO 3 compounds from microscopic theory (2008) Journal of Alloys and Compounds, 456 (1-2), pp. 508-513. , DOI 10.1016/j.jallcom.2007.02.133, PII S0925838807005397Bagayoko, D., Zhao, G.L., Fan, J.D., Wang, J.T., (1998) J. Phys. Condens. Matter, 10, p. 5645. , 10.1088/0953-8984/10/25/014Von Ranke, P.J., Mota, M.A., Grangeia, D.F., Carvalho, A.M.G., Gandra, F.C.G., Coelho, A.A., Caldas, A., Gama, S., Magnetocaloric effect in the RNi 5 (R = Pr, Nd, Gd, Tb, Dy, Ho, Er) series (2004) Physical Review B - Condensed Matter and Materials Physics, 70 (13), pp. 1344281-1344286. , DOI 10.1103/PhysRevB.70.134428, 13442

The Giant Anisotropic Magnetocaloric Effect In Dyal2

We report on calculations of the anisotropic magnetocaloric effect in DyAl2 using a model Hamiltonian including crystalline electrical field effects. The anisotropic effect is produced by the rotation of a constant magnetic field from the easy to a hard magnetic direction in the crystal and is enhanced by the first order nature of the field induced spin reorientation transition. The calculated results indicate that for a field with modulus of 2 T rotating from a hard to the easy direction, the isothermal magnetic entropy (Δ Siso) and adiabatic temperature (Δ Tad) changes present peak values higher than 60% the ones observed in the usual process, in which the field direction is kept constant and the modulus of the field is varied. © 2008 American Institute of Physics.1049Tishin, A.M., Spichkin, Y.I., (2003) The Magnetocaloric Effect and Its Applications, , 1st ed. (Institute of Physics, Bristol)Warburg, E., (1881) Ann. Phys. (N.Y.), 13, p. 141. , 0003-4916Brown, G.V., (1976) J. Appl. Phys., 47, p. 3673. , 0021-8979 10.1063/1.323176Pecharsky, V.K., Gschneidner Jr., K.A., (1997) Phys. Rev. Lett., 78, p. 4494. , 0031-9007 10.1103/PhysRevLett.78.4494Von Ranke, P.J., De Oliveira, N.A., Mello, C., Garcia, D.C., De Souza, V.A., Magnus, A., Carvalho, G., (2006) Phys. Rev. B, 74, p. 054425. , 0163-1829 10.1103/PhysRevB.74.054425Hill, T.W., Wallace, W.E., Craig, R.S., Inuone, T.J., (1973) Solid State Chem., 8, p. 364. , 10.1016/S0022-4596(73)80036-2De Oliveira, I.G., Garcia, D.C., Von Ranke, P.J., (2007) J. Appl. Phys., 102, p. 073907. , 0021-8979 10.1063/1.2783781Lima, A.L., Tsokol, A.O., Gschneidner Jr., K.A., Pecharky, V.K., Lograsso, T.A., Schlagel, D.L., (2005) Phys. Rev. B, 72, p. 024403. , 0163-1829 10.1103/PhysRevB.72.024403Von Ranke, P.J., De Oliveira, I.G., Guimarães, A.P., Da Silva, X.A., (2000) Phys. Rev. B, 61, p. 447. , 0163-1829 10.1103/PhysRevB.61.447Von Ranke, P.J., De Oliveira, N.A., Garcia, D.C., De Sousa, V.S.R., De Souza, V.A., Magnus, A., Carvalho, G., Reis, M.S., (2007) Phys. Rev. B, 75, p. 184420. , 0163-1829 10.1103/PhysRevB.75.184420Purwins, H.G., Leson, A., (1990) Adv. Phys., 39, p. 309. , 0001-8732 10.1080/00018739000101511Von Ranke, P.J., Pecharsky, V.K., Gschneidner Jr., K.A., (1998) Phys. Rev. B, 58, p. 1211

A large community outbreak of Legionnaires’ disease in Vila Franca de Xira, Portugal, October to November 2014

An outbreak of Legionnaires’ disease with 334 confirmed cases was identified on 7 November 2014 in Vila Franca de Xira, Portugal and declared controlled by 21 November. Epidemiological, environmental and microbiological analysis identified industrial wet cooling systems to be the probable source of infection. Preliminary results from sequence-based typing of clinical specimens and environmental isolates confirmed this link. A series of meteorological phenomena are likely to have contributed to the scale of this outbreak

Experimental And Theoretical Analyses Of Pr Al2 And Nd Al2 Composite For Use As An Active Magnetic Regenerator

We report the theoretical and experimental investigations on the magnetocaloric effect in the Pr Al2 and Nd Al2 compounds and a composite of these compounds for use as an active magnetic regenerator. The theoretical calculations were performed considering the crystalline electrical field anisotropy and the magnetocaloric potentials were calculated in the three main crystallographic directions. The experimental data, obtained for the polycrystalline samples, are in good agreement with the theoretical results. Also, an optimum molar fraction of the Pr Al2 and Nd Al2 composite was determined theoretically and experimentally and discussed in the framework of the optimum regeneration Ericsson cycle. © 2005 American Institute of Physics.978Brown, G.V., (1976) J. Appl. Phys., 47, p. 3673Pecharsky, V.K., Gschneidner Jr., K.A., (1997) Phys. Rev. Lett., 78, p. 4494Tegus, O., Bruck, E., Buschow, K.H.J., De Boer, F.R., (2002) Nature (London), 415, p. 150Wada, H., Taniguchi, K., Tanabe, Y., (2002) Mater. Trans., JIM, 43, p. 73Wada, H., Tanabe, Y., (2001) Appl. Phys. Lett., 79, p. 3302Von Ranke, P.J., Nobrega, E.P., De Oliveira, I.G., Gomes, A.M., Sarthour, R.S., (2001) Phys. Rev. B, 63, p. 184406Von Ranke, P.J., De Oliveira, N.A., Tovar Costa, M.V., Caldas, A., De Oliveira, I.G., Nobrega, E.P., (2001) J. Magn. Magn. Mater., 226, p. 990Von Ranke, P.J., Pecharsky, V.K., Gschneidner Jr., K.A., (1998) Phys. Rev. B, 58, p. 12110Von Ranke, P.J., De Oliveira, I.G., Guimarães, A.P., Da Silva, X.A., (2000) Phys. Rev. B, 61, p. 447Williams, H.J., Wernick, J.H., Nesbit, E.A., Sherwood, R.C., (1962) J. Phys. Soc. Jpn., 17, p. 91Swift, W.M., Wallace, W.E., (1968) J. Phys. Chem. Solids, 29, p. 2053Mader, K.H., Segal, E., Wallace, W.E., (1969) J. Phys. Chem. Solids, 30, p. 1Nereson, N., Olsen, C., Arnold, G., (1968) J. Appl. Phys., 39, p. 4605Nereson, N., Olsen, C., Arnold, G., (1966) J. Appl. Phys., 37, p. 4575Rossignol, M.F., (1980), University of GrenoblePurwins, H.G., Leson, A., (1990) Adv. Phys., 39, p. 309Lima, A.L., Oliveira, I.S., Gomes, A.M., Von Ranke, P.J., (2002) Phys. Rev. B, 65, p. 172411Hashimoto, T., Kuzuhara, T., Sahashi, M., Inomata, K., Tomokiyo, A., Yayama, H., (1991) J. Appl. Phys., 70, p. 1911Yan, Z., Chen, J., (1992) J. Appl. Phys., 72, p. 1Smaïli, A., Chahine, R., (1996) Adv. Cryog. Eng., 42, p. 445Dai, W., (1992) J. Appl. Phys., 71, p. 527

Galvanic oxidation of bimetallic Zn-Fe nanoparticles for oxygen scavenging

Bimetallic nanoparticles (NP) have demonstrated outstanding multifunctional characteristics, which depend on their size, distribution and composition. In this study, we show the possibility of tailoring the oxidation behavior of Zn-Fe bimetallic nanoparticles produced by magnetron sputtering and gas agglomeration system. Zn and Fe metals were coupled to promote faster oxidation of Zn, stimulating a galvanic mechanism due to the dissimilar corrosion potential in the nanoparticles. The results revealed Zn dissolution occurring at high humidity environments for bimetallic Zn-Fe nanoparticles where no intermix exists between Zn and Fe; however, such dissolution is excluded for ZnFe alloys. The effect of the galvanic couple on the Zn dissolution was confirmed by molecular dynamic simulations. This bimetallic system can be exploited as moisture-activated oxygen scavenger materials due to the acceleration in the oxidation mechanism.This research is sponsored by FEDER funds through the program COMPETE – Programa Operacional Factores de Competitividade and by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Funding UID/FIS/04650/2019, and UID/ EMS/00285/2013 and in the framework of ERA-SIINN/0004/2013, PTDC/CTM-NAN/4242/2014 and PTDC/NAN-MAT/30789/2017 projects, and through IDMEC, under LAETA, project UIDB/50022/2020. This research was supported by Norte Regional Operational Program 2014-2020 (Norte2020) through the European Regional Development Fund (ERDF) Nanotechnology based functional solutions (NORTE-01- 0145-FEDER-000019) and through European Social Fund (FSE), under the National Doctoral Program in “Surfaces Engineering and Protection”, NORTE-08-5369-FSE-000047. The authors would like to acknowledge that this project received funding from the EU Framework Programme for Research and Innovation H2020, scheme COFUND – Cofunding of Regional, National and International Programmes, under Grant Agreement 713640. The authors also thank the financial support by Portuguese Foundation for Science and Technology (FCT) in the framework of the HEALTHYDENT (co-financed via FEDER (PT2020) POCI-01-0145-FEDER-030708 and FCT (PIDDAC)), in the framework of the ATRITO-0 (co-financed via FEDER (PT2020) POCI-01-0145-FEDER030446 and FCT (PIDDAC)) and in the framework of the project NANOXYPACK co-financed via FEDER (PT2020) POCI-01-0145-FEDER030789