A comparative experimental study on the impact of standard and torrefied wood pellets on the drive parameters of a stratified batch gasifier

In these last years gasification studies have mainly involved raw biomasses. Recently, torrefied lignocellulosic materials have become particularly attractive but the majority of the investigations regarding this thermal treatment have been limited to the characterization of the feedstocks submitted to a wide range of working conditions. Only a limited and well documented number of works specifically dedicated to gasification of torrefied biomasses have been till now published. Most of these works, indeed, report results refer to industrial or pilot plants working within limited range conditions. As a consequence, extended investigations of the impact of the guide parameters of this process on a wide working conditions spectrum are not so easy to found. This work presents the results of an extended experimental campaign carried out on a specific small gasifier designed for a batch configuration and using air as gasification agent. The peculiarity of this experimental study consists in an on line monitoring of the biomass loss during the gasification process and in a direct experimental determination of the main parameters of the process as: the productivity of the syngas, its heating value, the amount of the remaining char, the power of the gasifier and the cold efficiency of the process. In particular the role of the air flow rate as critical parameter and its impact on the cited quantities is highlighted. For this investigation the results obtained for gasification tests of both commercial pellet (CP) and torrefied pellet (TP) characterized by a Mass Yield close to 80% are presented. The adopted experimental device allows to select several air flow rate ranging from 15 to 30 Nl·min-1. The L.H.V. of the syngas reaches values in the range 3.51 \u3c L.H.V. \u3c 3.85 and 4.14 \u3c L.H.V. \u3c 4.31 for CP and TP respectively. The maximum power values set at 2.73 kW for CP and 3.53 kW for TP. Interesting results can be deduced by reporting the trend of the cited quantities Vs. the air flow rate. As general result, the use of torrefied material confirms a significant improvement of the performances of the gasification process compared to those involving conventional biomasses. Please click Additional Files below to see the full abstract

Galactic Outflows and the pollution of the Galactic Environment by Supernovae

We here explore the effects of the SN explosions into the environment of star-forming galaxies like the Milky Way. Successive randomly distributed and clustered SNe explosions cause the formation of hot superbubbles that drive either fountains or galactic winds above the galactic disk, depending on the amount and concentration of energy that is injected by the SNe. In a galactic fountain, the ejected gas is re-captured by the gravitational potential and falls back onto the disk. From 3D nonequilibrium radiative cooling hydrodynamical simulations of these fountains, we find that they may reach altitudes up to about 5 kpc in the halo and thus allow for the formation of the so called intermediate-velocity-clouds (IVCs) which are often observed in the halos of disk galaxies. The high-velocity-clouds that are also observed but at higher altitudes (of up to 12 kpc) require another mechanism to explain their production. We argue that they could be formed either by the capture of gas from the intergalactic medium and/or by the action of magnetic fields that are carried to the halo with the gas in the fountains. Due to angular momentum losses to the halo, we find that the fountain material falls back to smaller radii and is not largely spread over the galactic disk. Instead, the SNe ejecta fall nearby the region where the fountain was produced, a result which is consistent with recent chemical models of the galaxy. The fall back material leads to the formation of new generations of molecular clouds and to supersonic turbulence feedback in the disk.Comment: 10 pages, 5 figures; paper of invited talk for the Procs. of the 2007 WISER Workshop (World Space Environment Forum), Alexandria, Egypt, October 2007, Spa. Sci. Rev

Turbulent Mixing in Clusters of Galaxies

We present a spherically-symmetric, steady-state model of galaxy clusters in which radiative cooling from the hot gas is balanced by heat transport through turbulent mixing. We assume that the gas is in hydrostatic equilibrium, and describe the turbulent heat diffusion by means of a mixing length prescription with a dimensionless parameter alpha_mix. Models with alpha_mix ~ 0.01-0.03 yield reasonably good fits to the observed density and temperature profiles of cooling core clusters. Making the strong simplification that alpha_mix is time-independent and that it is roughly the same in all clusters, the model reproduces remarkably well the observed scalings of X-ray luminosity, gas mass fraction and entropy with temperature. The break in the scaling relations at kT \~ 1-2 keV is explained by the break in the cooling function at around this temperature, and the entropy floor observed in galaxy groups is reproduced naturally.Comment: Accepted for publication in ApJ

Chloris polydactyla (L.) Sw., a perennial Poaceae weed: emergence, seed production, and its management in Brazil.

Experiments were conducted to evaluate the plant emergence and seed production of Chloris polydactyla and the efficacy of herbicides for its control. The plants emerged mainly when the seeds were placed on the soil surface at ≤ 3 cm depth. Isolated plants produced a great amount of seeds. The pre-emergence herbicides, acetochlor, atrazine + simazine, s-metolachlor, alachlor, and trifluralin, were effective for C. polydactyla control. The postemergence herbicides, clodinafop-propargil, haloxyfop-methyl, clethodim, fluazifop-p-butil, tepraloxydim, sethoxydim, and quizalofop-p-tefuril showed satisfactory control of the plants at a 20 cm height with six leaves. During the flowering stage (85 cm plant height), only glyphosate was effective in controlling C. polydactyla

Apparent high metallicity in 3-4 keV galaxy clusters: the inverse iron-bias in action in the case of the merging cluster Abell 2028

Recent work based on a global measurement of the ICM properties find evidence for an increase of the iron abundance in galaxy clusters with temperature around 2-4 keV up to a value about 3 times larger than that typical of very hot clusters. We have started a study of the metal distribution in these objects from the sample of Baumgartner et al. (2005), aiming at resolving spatially the metal content of the ICM. We report here on a 42ks XMM observation of the first object of the sample, the cluster Abell 2028. The XMM observation reveals a complex structure of the cluster over scale of 300 kpc, showing an interaction between two sub-clusters in cometary-like configurations. At the leading edges of the two substructures cold fronts have been detected. The core of the main subcluster is likely hosting a cool corona. We show that a one-component fit for this region returns a biased high metallicity. This inverse iron bias is due to the behavior of the fitting code in shaping the Fe-L complex. In presence of a multi-temperature structure of the ICM, the best-fit metallicity is artificially higher when the projected spectrum is modeled with a single temperature component and it is not related to the presence of both Fe-L and Fe-K emission lines in the spectrum. After accounting for the bias, the overall abundance of the cluster is consistent with the one typical of hotter, more massive clusters. We caution the interpretation of high abundances inferred when fitting a single thermal component to spectra derived from relatively large apertures in 3-4 keV clusters, because the inverse iron bias can be present. Most of the inferences trying to relate high abundances in 3-4 keV clusters to fundamental physical processes will likely have to be revised.Comment: 13 pages, 8 figures.Accepted for publication in Astronomy and Astrophysycs. Minor changes to match published versio

Girassol Clearfield consorciado com Brachiaria ruziziensis utilizando herbicidas inibidores da enzima aceto-lactato sintase (ALS).

O objetivo desse experimento foi avaliar a tolerância do girassol (Helianthus annuus) e a supressão do capim-braquiária (Brachiaria ruziziensis) a herbicidas inibidores da enzima aceto-lactato sintase (ALS). O delineamento experimental foi blocos casualizados, com quatro repetições. Os tratamentos foram i) imazethapyr 30 g i.a./ha; ii) imazethapyr 70 g i.a./ha; iii) imazapyr 75 g e.a./ha; iv) imazapyr 125 g e.a./ha; v) chlorimuron-ethyl 7,5 g i.a./ha; vi) chlorimuron-ethyl 12,5 g i.a./ha; vii) nicosulfuron 8 g i.a./ha; viii) nicosulfuron 20 g i.a./ha; ix) testemunha sem capina e x) testemunha capinada. Os tratamentos com imazethapyr (30 e 70 g i.a./ha), imazapyr (75 e 125 g e.a./ha) e nicosulfuron (8 e 20 g i.a./ha) não causaram injúrias às plantas de girassol. O chlorimuron-ethyl nas doses de 7,5 e 12,5 g i.a./ha resultou em alto grau de fitointoxicação às plantas de girassol. O imazethapyr (30 e 70 g i.a./ha) e o nicosulfuron (8 g i.a./ha) causaram supressão do crescimento das plantas de B. ruziziensis. Entretanto, o imazapyr (75 e 125 g e.a./ha) e a maior dose de nicosulfuron (20 g i.a./ha) afetaram drasticamente a produção de fitomassa da forrageira, com morte das plantas

Tolerância diferencial de genótipos Clearfield e convencional aos herbicidas inibidores da enzima ALS.

O objetivo do presente trabalho foi comparar a sensibilidade de dois genótipos de girassol, um resistente (Paraiso 102 CL- Clearfield) e outro suscetível (Embrapa 122 V2000) aos herbicidas inibidores da enzima acetolactato sintase (ALS). O delineamento experimental foi blocos ao acaso, em parcelas subdivididas, com quatro repetições. Nas parcelas, foram avaliados dois cultivares de girassol, um resistente (Paraiso 102 CL) e outro suscetível (Embrapa 122 V2000) aos herbicidas inibidores da enzima acetolactato sintase. Nas subparcelas, foram aplicados sete tratamentos (i) testemunha capinada, (ii) testemunha sem capina, (iii) imazethapyr 100 g i.a./ha, (iv) imazapyr 250 g i.a./ha, (v) imazapyr 25 g i.a./ha, (vi) nicosulfuron 60 g i.a./ha e (vii) nicosulfuron 4 g i.a./ha. O imazethapyr 100 g i.a./ha, o imazapyr 25 g i.a./ha e o nicosulfuron 4 g i.a./ha proporcionaram valores baixos de fitotoxicidade ao girassol Paraíso 102 CL. Todos os tratamentos herbicidas e respectivas doses causaram alto grau de fitotoxicidade às plantas de girassol Embrapa 122 V2000

Avaliação da influência da temperatura no desenvolvimento de buva, caruru e capim-amargoso.

O objetivo deste trabalho foi comparar as características do crescimento e desenvolvimento de plantas de Conyza spp (buva), Amaranthus deflexus (caruru) e Digitaria insularis (capim-amargoso), dispostas em ambiente natural, a céu aberto, e em câmaras climatizadas do tipo fitotron com alternância de temperatura 25º/15ºC (diurna/noturna, equivalente a 12 horas com luz /12 horas sem luz), 25º/10ºC, 25º/5ºC. O delineamento experimental foi inteiramente casualizado, com quatro repetições. As plantas foram coletadas a intervalos regulares de sete dias após o plantio (DAP), sendo determinados os valores médios da área foliar, da matéria seca total, do comprimento e da matéria seca de caule e da altura de plantas. A simulação da alternância da temperatura noturna influenciou o crescimento e desenvolvimento das espécies estudadas. As maiores influências ocorrem principalmente com a temperatura mais baixa e entre as plantas do fitotron, em comparação com as cultivadas em céu aberto. Os comportamentos diferenciados estão associados às características das plantas avaliadas, mantidas em ambiente natural e em ambiente com alternância de temperatura, indicando que a temperatura pode ter influenciado no ciclo vegetativo. Apesar das respostas encontradas para algumas características analisadas, é importante ressaltar que dada à complexidade do assunto os resultados devem ser considerados como preliminares

Crescimento do capim-amargoso com a alternância de temperatura: 35ºC diurna e 20ºC noturna.

O objetivo deste trabalho foi comparar as características do crescimento de plantas de capim-amargoso (Digitaria insularis) dispostas em ambiente natural e em câmaras climatizadas do tipo fitotron com alternância de temperatura (35ºC diurna e 20ºC noturna), a fim de identificar diferenças no crescimento e no desenvolvimento das plantas. O delineamento experimental foi inteiramente casualizado, com quatro repetições. As plantas foram coletadas a intervalos regulares de sete dias em sete dias após o plantio (DAP), variando de 0 a 70dias. Este procedimento permitiu aplicar o método de analise de regressão. Foram determinados os valores médios da área foliar, da altura de plantas, do comprimento de caule e da matéria seca de raízes. A alternância da temperatura influenciou no ciclo vegetativo das plantas de capim-amargoso. A área foliar e a altura das plantas mantidas em ambiente natural e em ambiente com alternância de temperatura apresentaram comportamentos diferenciados a partir dos 35 e 42 DAP, respectivamente. O comprimento de caule e a matéria seca de raízes apresentaram comportamentos diferenciados a partir dos 28 e 21 DAP, respectivamente. As características de crescimento avaliadas nas plantas de D. insularis mantidas em ambiente natural e em ambiente com alternância de temperatura apresentaram comportamentos diferenciados, indicando que a temperatura pode ter influenciado no ciclo vegetativo dessa espécie daninha.1 CD-ROM

Consórcio de girassol e Brachiaria ruziziensis utilizando subdoses de herbicidas graminicidas.

O objetivo desse trabalho foi avaliar a supressão do capim-braquiária (Brachiaria ruziziensis) em consórcio com o girassol (Helianthus annuus) e submetida a doses reduzidas de herbicidas inibidores da acetil coenzima A carboxilase (ACCase). O delineamento experimental foi em blocos casualizados, com três repetições. Os tratamentos foram i) testemunha capinada; ii) testemunha sem capina; iii) tepraloxydim 10 g i.a./ha; iv) tepraloxydim 20 g i.a./ha; v) tepraloxydim 40 g i.a./ha; vi) fluazifop-p-butyl 12,5 g i.a./ha; vii) fluazifop-p-butyl 25,0 g i.a./ha; viii) fluazifop-p-butyl 50,0 g i.a./ha. É viável a utilização de doses reduzidas de graminicidas como reguladores de crescimento da B. ruzizizensis. Todos os herbicidas e doses aplicadas foram seletivos para a cultura do girassol. O herbicida tepraloxydim na menor dose (10 g i.a./ha) reduziu o crescimento da forrageira e as duas maiores doses 20 e 40 g i.a./ha causaram alto grau de fitotoxicidade às plantas de B. ruzizizensis e redução total da produção de forragem. As doses do fluazifop-p-butyl suprimiram o crescimento do capim-braquiária, havendo redução de produção de forragem com o aumento das doses desse herbicida