INFLUENCE OF MARKET DIVERSIFICATION ON FARM INCOME VARIABILITY OF SOYBEAN PRODUCERS

Crop Production/Industries,

Tribological behaviour of copper oxide nanoparticle suspension

This work presents and discusses the tribological behaviour of nanoparticle suspensions in a polyalphaolefin (PAO6). CuO nanoparticles were separately dispersed at 0.5, 1.0 and 2.0% wt. in PAO6 using an ultrasonic probe for 2 minutes. AW properties were obtained using a TE53SLIM tribometer with a block-on-ring configuration and EP properties were obtained using a Four-Ball machine according to ASTM D2783. Wear surfaces were analyzed by SEM and EDS after tests. The study led to the following conclusions: nanoparticle suspensions exhibited reductions in friction and wear compared to the base oil; CuO suspensions showed the highest friction coefficient and lowest wear per nanoparticle content of 2%; all concentrations of nanoparticles improved the EP properties of PAO6; CuO showed better results at 0.5% wt. of nanoparticles; and the antiwear mechanism of nanoparticulate additive was produced by tribo-sintering

Viscosity and tribology of copper oxide nanofluids

Nanofluids, a term proposed by Choi in 1995 [1], are composites consisting of solid nanoparticles with sizes varying generally from 1 to 100 nm dispersed in a liquid. Numerous nanoparticles used as oil additives have been investigated in recent years [2-7]. Results show that they deposit on the rubbing surface and improve the tribological properties of the base oil, displaying good friction and wear reduction characteristics even at concentrations below 2%wt. Although the viscosity of the nanofluids is a property of crucial importance for film forming, and hence friction and wear reduction, which are characteristic of lubricants, only Hwang et al. [8] have studied thermal characteristics, kinematic viscosity and tribological properties of nanofluids simultaneously. In this paper, we present measurements of dynamic viscosity of nanofluids formed by copper oxide nanoparticles dispersed in a polyalphaolefin, for temperatures and concentrations varying from 20 to 60ºC and 0.5 to 2% wt., respectively. Dependence of the nanofluid viscosity to the solid fraction and temperature was compared with existing models and its influence on lubrication was also analysed

Length-weight relationships of coral reef fishes from the Alacran Reef, Yucatan, Mexico

Length-weight relationships were computed for 42 species of coral reef fishes from 14 families from the Alacran Reef (Yucatan, Mexico). A total of 1 892 individuals was used for this purpose. The fish species were caught by different fishing techniques such as fishhooks, harpoons, gill and trawl nets. The sampling period was from March 1998 to January 2000

Constraining the period of the ringed secondary companion to the young star J1407 with photographic plates

Context. The 16 Myr old star 1SWASP J140747.93-394542.6 (V1400 Cen) underwent a series of complex eclipses in May 2007, interpreted as the transit of a giant Hill sphere filling debris ring system around a secondary companion, J1407b. No other eclipses have since been detected, although other measurements have constrained but not uniquely determined the orbital period of J1407b. Finding another eclipse towards J1407 will help determine the orbital period of the system, the geometry of the proposed ring system and enable planning of further observations to characterize the material within these putative rings. Aims. We carry out a search for other eclipses in photometric data of J1407 with the aim of constraining the orbital period of J1407b. Methods. We present photometry from archival photographic plates from the Harvard DASCH survey, and Bamberg and Sonneberg Observatories, in order to place additional constraints on the orbital period of J1407b by searching for other dimming and eclipse events. Using a visual inspection of all 387 plates and a period-folding algorithm we performed a search for other eclipses in these data sets. Results. We find no other deep eclipses in the data spanning from 1890 to 1990, nor in recent time-series photometry from 2012-2018. Conclusions. We rule out a large fraction of putative orbital periods for J1407b from 5 to 20 years. These limits are still marginally consistent with a large Hill sphere filling ring system surrounding a brown dwarf companion in a bound elliptical orbit about J1407. Issues with the stability of any rings combined with the lack of detection of another eclipse, suggests that J1407b may not be bound to J1407.Comment: 8 pages, 3 tables, 4 figures, accepted for publication in A&A. LaTeX files of the paper, scripts for the figures, and a minimal working FPA can be found under https://github.com/robinmentel/Constraining-Period

The contribution of Narrow-Line Seyfert 1 galaxies to the soft X-ray background

The ROSAT Ultradeep HRI survey in the Lockman Hole contains a complete sample of 91 X-ray sources with fluxes in the 0.5-2 keV band larger than 1.2 times 10e-15 erg cm-2 s-1, where over about 75 per cent of the sources are quasars or Seyfert galaxies. During the course of our optical identification work, we have obtained optical spectra of 67 narrow emission line galaxies (NELG), which are physically not associated with the X-ray sources. We have derived the equivalent width (EW) and the full width at half maximum (FWHM) for the most prominent emission lines of 41 quasars and Seyfert galaxies taken from the ROSAT Deep Survey (RDS), which has a flux limit of 5.5 times 10e-15 erg cm-2 s-1 in the 0.5-2.0 keV band. Furthermore we have obtained the EW and FWHM values of the field NELGs. Here we present the spectroscopic discrimination between RDS Seyfert galaxies and field galaxies (NELG). The analysis of the emission lines has revealed that a single object out of 69 spectroscopically identified AGN fits the optical criteria of Narrow-Line Seyfert 1 galaxies (NLS1). This may indicate that NLS1 contribute only marginally to the soft X-ray background, but we can not exclude a possible larger contribution.Comment: Invited talk presented at the Joint MPE,AIP,ESO workshop on NLS1s, Bad Honnef, Dec. 1999, to appear in New Astronomy Reviews; also available at http://wave.xray.mpe.mpg.de/conferences/nls1-worksho

Estudio del apoyo metatarsal en bipedestación mediante podoscopio electrónico de alta resolución.

Con el jin de estudiar el apoyo metatarsal en bipedestación se han realizado 780 registros en la plataforma PDS 93, correspondientes a 390 individuos, no seleccionados, sin patología de la marcha, 234 varones y 156 mujeres, con edades comprendidas entre 24 y 41 años (edad media de 29,9 años). En cada registro se ha recogido la presión ejercida por cada metatarsiano, relacionando la carga obtenida con el peso, conjiguración mecánica del pie y huella plantar: Los resultados obtenidos se han procesado estadísticamente por medio del programa SPSS. El porcentaje de las cargas medias obtenidas para cada metatarsiano han sido: 16,85, 21,25, 23,88, 20,24 y 17,78%, existiendo dqerencias sign$cativas para el apoyo de los metatarsianos centrales (p < 0,001). Todos los metatarsianos soportan carga en bipedestación, de acuerdo con las teorías actuales. Sin embargo, aunque la distribución del peso para el primer metatarsiano se aproxima al doble de los otros, la carga máxima en g/cm2 se realiza en los metatarsianos centrales

Ferromagnetic Polarons in La0.5Ca0.5MnO3 and La0.33Ca0.67MnO3

Unrestricted Hartree-Fock calculations on La0.5Ca0.5MnO3 and La0.33Ca0.67MnO3 in the full magnetic unit cell show that the magnetic ground states of these compounds consist of 'ferromagnetic molecules' or polarons ordered in herring-bone patterns. Each polaron consists of either three or five Mn ions separated by O- ions with a magnetic moment opposed to those of the Mn ions. Ferromagnetic coupling within the polarons is strong while coupling between them is relatively weak. Magnetic moments on the Mn ions range between 3.8 and 3.9 Bohr magnetons in La0.5Ca0.5MnO3 and moments on the O- ions are -0.7 Bohr magnetons. Each polaron has a net magnetic moment of 7.0 Bohr magnetons, in good agreement with recently reported magnetisation measurements from electron microscopy. The polaronic nature of the electronic structure reported here is obviously related to the Zener polaron model recently proposed for Pr0.6Ca0.4MnO3 on the basis of neutron scattering data.Comment: 4 pages 5 figure

Madera de compresión en Pinus radiata III: Propiedades de pulpas kraft

Estudios anteriores en estos mismos árboles de Pinus radiata con fustes levemente inclinados, demostraron que la madera de compresión leve que ellos exhibían presentaba: traqueidas más cortas, mayor densidad, mayor proporción de lignina, mayor proporción de extraíbles en etanol tolueno y menor proporción de alfa celulosa que la madera opuesta y que la madera de árboles sin madera de compresión.En el presente estudio se analiza las propiedades pulpables de la madera de compresión y la de sus respectivas maderas opuestas de los quince árboles de Pinus radiata estudiados, crecidos en suelos de arena húmeda en Chile. Se estudió separadamente la madera de compresión y la madera opuesta. Con distintas proporciones, de entre 0, 40, 70 y 100 % de madera de compresión y madera opuesta, se efectuaron pulpajes kraft  para cada una de las mezclas.De estos pulpajes con y sin blanqueo se informan valores de 501 y 695 kg/m3 de densidad; 28 a 51 Nm/g en índice de tensión, 18 a 25 mNm2/g en índice de rasgado, 2.2 a 4.1 kPam2/g en índice de explosión y rendimiento de 44 a 50.6 % en las mezclas de la pulpa estudiada.En la pulpa cruda de MC, de la madera pulpable y de la madera exterior aserrable, se registró me-nor densidad, mayor índice de tensión, de rasgado y de explosión, en comparación con los resultados obtenidos en la pulpa cruda de MO. En el caso de las pulpas blanqueadas, la densidad y el índice de tensión resultaron mayores en la MC.En el resto de las propiedades las diferencias entre MC y MO fueron oscilantes y reducidas. El aumento de la proporción de MC en la mezcla de MC y MO, produjo una reducción de rendimiento. Los rendimiento de las mezclas de la madera pulpable indicaron para el 100 % de MO un 50.6 % y para el 100% de MC un 44 %: En los casos de las pulpas de madera exterior aserrable el 100% de MO tuvo un rendimiento de de 48.4% en cambio el 100% de la MC registró un 44.3%.Los resultados obtenidos indicaron que la MC leve, que se encuentra en árboles con inclinaciones menores, tuvo un efecto de menor magnitud que él que se produce en la MC severa sobre las características y rendimiento de la pulpa kraft. AbstractPrevious studies with radiata pine trees growing slightly leaned towards one side showed that they have small amounts of compression wood with different characteristics than the opposite wood at the other side of the annual rings. These differences include shorter tracheids, higher density, higher proportion of lining, higher proportion of extractives in toluene ethanol, and a smaller amount of alpha-cellulose.The present study compares the properties of kraft pulp, with and without bleaching, for mixtures of compression and opposite wood obtained from fifteen 22-year-old radiata pine trees that grew in humid sand soils of Chile. The kraft pulp mixture was studied for different proportions of 0, 40, 70 and 100% compression wood. Considering all mixtures with and without bleaching, the study reports values between 501 and 695 kg/m3 density, 28 and 51 Nm/g tension index, 18 and 25 mNm2/g tear index, 2,2 and 4,1 kPam2 burst index, and 44% and 50,6% pulp yield.It was found that the pulp without bleaching from compression wood (for both the internal pulp and the external lumber areas) had lower density, but higher tension, tear, and burst indexes. The pulp with bleaching from compression wood had both higher density and tension index, but the other properties only show small random differences with respect to opposite wood.A higher proportion of compression wood in the mixture reduced pulp yield. The yield for the internal pulp area was 50,6 % with pure opposite wood and 44% with pure compression wood, while the yield for external lumber area was 48,4% with pure opposite wood and 44,3% with pure compression wood. I was concluded, however, that the relatively small amount of compression wood found in these trees had only a minor effect in the properties and yield of kraft pulp