Estudio de la electro-filtración a presión constante de suspensiones sólido-líquido

Debido a que los sistemas de filtración utilizados actualmentesólo pueden eliminar una parte del agua contenida en la suspensión, se han realizado investigaciones con elobjetivo de obtener mayores rendimientos en la filtraciónmediante la aplicación de un campo eléctrico en un filtro presión. Para ello, se han llevado a cabo electro-filtracionesaplicando una diferencia de presión constante de0.4 bar y diferentes valores de intensidad eléctrica (de 0 a2.21 A). Se ha estudiado la influencia del campo eléctricosobre el contenido en agua de la torta, la presión electroosmótica, a resistencia específica de la torta y el pH delfiltrado y del agua retenida en la torta. Se ha analizado elefecto de la electroforesis y de la electro-ósmosis sobreestas propiedades. El estudio de la variación del pH determinaque la operación unitaria de electro-filtración sóloes aplicable en los procesos donde el sólido obtenido seaun residuo o cuyas propiedades puedan ser modificadas.Por fin, se ha definido un nuevo parámetro que tiene encuenta la compresibilidad de la torta según la intensidadeléctrica aplicada y ha convenido en denominarse factorde electro-compresibilidad

Star formation in low density HI gas around the Elliptical Galaxy NGC2865

Interacting galaxies surrounded by HI tidal debris are ideal sites for the study of young clusters and tidal galaxy formation. The process that triggers star formation in the low-density environments outside galaxies is still an open question. New clusters and galaxies of tidal origin are expected to have high metallicities for their luminosities. Spectroscopy of such objects is, however, at the limit of what can be done with existing 8-10m class telescopes, which has prevented statistical studies of these objects. NGC2865 is an UV-bright merging elliptical galaxy with shells and extended HI tails. The regions observed in this work were previously detected using multi-slit imaging spectroscopy. We obtain new multislit spectroscopy of six young star-forming regions around NGC2865, to determine their redshifts and metallicities. The six emission-line regions are located 16-40 kpc from NGC2865 and they have similar redshifts. They have ages of ~10Myears and an average metallicity of 12+log(O/H) ~ 8.6, suggesting a tidal origin for the regions. It is noted that they coincide with an extended HI tail, which has projected density of N$_{HI}$ < 10$^{19}$ cm$^{-2}$, and displays a low surface brightness counterpart. These regions may represent the youngest of the three populations of star clusters already identified in NGC2865. The high, nearly-solar, oxygen abundances found for the six regions in the vicinity of NGC2865 suggest that they were formed by pre-enriched material from the parent galaxy, from gas removed during the last major merger. Given the mass and the location of the HII regions, we can speculate that these young star-forming regions are potential precursors of globular clusters that will be part of the halo of NGC2865 in the future. Our result supports the use of the multi-slit imaging spectroscopy as a useful tool for finding nearly-formed stellar systems around galaxies.Comment: 7 pages, 2 figures accepted in A&

K^0-\bar{K}^0 mixing in the Standard Model from Nf=2+1+1 Twisted Mass Lattice QCD

We present preliminary results at {\beta} = 1.95 (a = 0.077 fm) on the first unquenched N_f=2+1+1 lattice computation of the B_K parameter which controls the neutral kaon oscillations in the Standard Model. Using N_f=2+1+1 maximally twisted sea quarks and Osterwalder-Seiler valence quarks we achieve O(a) improvement and a continuum-like renormalization pattern for the four-fermion operator. Our results are extrapolated/interpolated to the physical light/strange quark mass but not yet to the continuum limit. The computation of the relevant renormalization constants is performed non perturbatively in the RI'-MOM scheme using dedicated simulations with N_f=4 degenerate sea quark flavours produced by the ETM collaboration. We get B_K^{RGI} (a = 0.077) = 0.747(18), which when compared to our previous unquenched N_f=2 determination and most of the existing results, suggests a rather weak B_K^{RGI} dependence on the number of dynamical flavours. We are at the moment analysing lattice data at two additional {\beta} values which will allow us to perform an extrapolation to the continuum limit.Comment: 7 pages, 8 figures, Proceedings of Lattice 2011, XXIX International Symposium on Lattice Field Theory, Squaw Valley, Lake Tahoe, Californi

Weak and Compact Radio Emission in Early High-Mass Star Forming Regions: II. The Nature of the Radio Sources

In this study we analyze 70 radio continuum sources associated with dust clumps and considered to be candidates for the earliest stages of high-mass star formation. The detection of these sources was reported by Rosero et al. (2016), who found most of them to show weak (${\scriptstyle <}$1 mJy) and compact (${\scriptstyle <}\,$0.6$^{\prime \prime}$) radio emission. Herein, we used the observed parameters of these sources to investigate the origin of the radio continuum emission. We found that at least $\sim 30\%$ of these radio detections are most likely ionized jets associated with high-mass protostars, but for the most compact sources we cannot discard the scenario that they represent pressure-confined HII regions. This result is highly relevant for recent theoretical models based on core accretion that predict the first stages of ionization from high-mass stars to be in the form of jets. Additionally, we found that properties such as the radio luminosity as a function of the bolometric luminosity of ionized jets from low and high-mass stars are extremely well-correlated. Our data improve upon previous studies by providing further evidence of a common origin for jets independently of luminosity.Comment: Accepted for publication in the Ap

Weak and Compact Radio Emission in Early High-Mass Star Forming Regions: I. VLA Observations

We present a high sensitivity radio continuum survey at 6 and 1.3$\,$cm using the Karl G. Jansky Very Large Array towards a sample of 58 high-mass star forming regions. Our sample was chosen from dust clumps within infrared dark clouds with and without IR sources (CMC-IRs, CMCs, respectively), and hot molecular cores (HMCs), with no previous, or relatively weak radio continuum detection at the $1\,$mJy level. Due to the improvement in the continuum sensitivity of the VLA, this survey achieved map rms levels of $\sim$ 3-10 $\mu$Jy beam$^{-1}$ at sub-arcsecond angular resolution. We extracted 70 centimeter continuum sources associated with 1.2$\,$mm dust clumps. Most sources are weak, compact, and are prime candidates for high-mass protostars. Detection rates of radio sources associated with the mm dust clumps for CMCs, CMC-IRs and HMCs are 6$\%$, 53$\%$ and 100$\%$, respectively. This result is consistent with increasing high-mass star formation activity from CMCs to HMCs. The radio sources located within HMCs and CMC-IRs occur close to the dust clump centers with a median offset from it of 12,000$\,$AU and 4,000$\,$AU, respectively. We calculated 5 - 25$\,$GHz spectral indices using power law fits and obtain a median value of 0.5 (i.e., flux increasing with frequency), suggestive of thermal emission from ionized jets. In this paper we describe the sample, observations, and detections. The analysis and discussion will be presented in Paper II.Comment: Accepted for publication in the ApJ

Near infrared and optical morphology of the dusty galaxy NGC972

Near infrared (NIR) and optical surface photometric analyses of the dusty galaxy NGC972 are presented. The photometric profiles in the BVRJHK bands can be fitted with a combination of gaussian and exponential profiles, corresponding to a starburst nucleus and a stellar disk respectively. The exponential scale length in the B-band is 2.8 times larger than in the K-band, which implies a central B-band optical depth as high as 11. A bulge is absent even in the NIR bands and hence the galaxy must be of a morphological type later than the usually adopted Sb type. Relatively low rotational velocity and high gas content also favor a later type, probably Sd, for the galaxy. Only one arm can be traced in the distribution of old stars; the second arm, however, can be traced in the distribution of dust and HII regions. Data suggest a short NIR bar, which ends inside the nuclear ring. The slowly rising nature of the rotation curve rules out a resonance origin of the the nuclear ring. The ring is most likely not in the plane of the galaxy, given its circular appearance in spite of the moderately high inclination of the galaxy. The off-planar nature of the star forming ring, the unusually high fraction (30%) of the total mass in molecular form, the presence of a nuclear starburst and the asymmetry of spiral arms, are probably the result of a merger with a gas-rich companion galaxy.Comment: Uses aas2pp4.sty and epsfig.sty, 12 pages To appear in Astronomical Journal, October 199

A determination of the average up-down, strange and charm quark masses from Nf=2+1+1N_f=2+1+1

We present a lattice QCD determination of the average up-down, strange and charm quark masses based on simulations performed by the European Twisted Mass Collaboration with $N_f = 2 + 1 + 1$ dynamical fermions. We simulated at three different values of the lattice spacing, the smallest being approximately $0.06fm$, and with pion masses as small as $210 \text{MeV}$. Our results are: $m_{ud}(2\text{GeV})=3.70(17)\text{MeV}$, $m_s(2\text{GeV})=99.2(3.9)\text{MeV}$, $m_c(m_c)=1.350(49)\text{GeV}$, $m_s/m_{ud}=26.64(30)$ and $m_c/m_s=11.65(12)$

Infrared-Emitting QDs for Thermal Therapy with Real-Time Subcutaneous Temperature Feedback

Nowadays, one of the most exciting applications of nanotechnology in biomedicine is the development of localized, noninvasive therapies for diverse diseases, such as cancer. Among them, nanoparticle-based photothermal therapy (PTT), which destroys malignant cells by delivering heat upon optical excitation of nanoprobes injected into a living specimen, is emerging with great potential. Two main milestones that must be reached for PTT to become a viable clinical treatment are deep penetration of the triggering optical excitation and real-time accurate temperature monitoring of the ongoing therapy, which constitutes a critical factor to minimize collateral damage. In this work, a yet unexplored capability of near-infrared emitting semiconductor nanocrystals (quantum dots, QDs) is demonstrated. Temperature self-monitored ­QD-based PTT is presented for the first time using PbS/CdS/ZnS QDs emitting in the second biological window. These QDs are capable of acting, simultaneously, as photothermal agents (heaters) and high-resolution fluorescent thermal sensors, making it possible to achieve full control over the intratumoral temperature increment during PTT. The differences observed between intratumoral and surface temperatures in this comprehensive investigation, through different irradiation conditions, highlight the need for real-time control of the intratumoral temperature that allows for a dynamic adjustment of the treatment conditions in order to maximize the efficacy of the therapyThis project has been supported by the Spanish Ministerio de Economía y Competitividad under project and MAT2013-47395-C4-1-R. B. del Rosal thanks Universidad Autónoma de Madrid for an FPI grant. F. Ren acknowledges scholarship support from the Fonds de recherche du Québec – Nature et technologies (FRQNT) under the Programme de Bourses d’Excellence (Merit Scholarship Program for Foreign Students