Influencia de la carga de sólido en la producción de D-xilosa mediante hidrólisis del hueso de aceituna con ácido sulfúrico diluido

The selective hydrolysis of hemicellulose from olive stones was attempted in order to achieve a maximum D-xylose yield. For this aim, batch hydrolysis was conducted under different operating conditions of temperature, acid concentration and solid loading. Firstly, distilled water, sulphuric acid and nitric acid were assessed as hydrolytic agents at different temperatures (200, 205, 210 and 220 °C) and at a fixed acid concentration (0.025 M). Sulphuric acid and 200 °C were selected for the subsequent dilute acid hydrolysis optimization based on the obtained D-xylose yields. The combined influence of solid loading (from 29.3 to 170.7 g olive stones into 300 mL acid solution) and sulphuric acid concentration (0.006–0.034 M) on the release of D-xylose was then estimated by response surface methodology. According to a statistical analysis, both parameters had significant interaction effects on D-xylose production. The results illustrated that the higher the solid loading, the higher the required acid concentration. The decrease in the solid/liquid ratio in the reactor had a positive effect on D-xylose extraction and on the amount of acid used. The optimum solid loading and sulphuric acid concentration were determined to be 50 g (solid/liquid ratio 1/6) and 0.016 M, respectively. Under these conditions, the predicted D-xylose yield (expressed as g of sugar per 100 g of dry matter fed) was 20.4 (87.2% of maximum attainable).Se ha desarrollado una hidrólisis selectiva de la fracción hemicelulósica del hueso de aceituna con el fin de obtener el máximo rendimiento de D-xilosa. Para ello las hidrólisis se llevaron a cabo en un reactor discontinuo a distintas condiciones de temperatura, concentración de ácido y carga de sólidos. En primer lugar se evaluó la capacidad hidrolítica del agua destilada y de los ácidos nítrico y sulfúrico a distintas temperaturas (200, 205, 210 y 220°C) manteniendo fija la concentración de ácido (0,025 M). A partir de los rendimientos en D-xilosa obtenidos se seleccionó el ácido sulfúrico y una temperatura de 200 °C para la posterior optimización del proceso. La influencia conjunta de la carga de sólidos (desde 29,3 a 170,7 g de hueso de aceituna en 300 mL de disolución ácida) y de la concentración de ácido sulfúrico (0,006–0,034 M) sobre los rendimientos de D-xilosa fue determinada mediante metodología de superficie de respuesta. Según el análisis estadístico ambos parámetros tuvieron un efecto interactivo significativo en la producción de D-xilosa. Los resultados mostraron que se requiere mayor concentración de ácido a mayor carga de sólidos. La disminución de la relación sólido/líquido en el reactor tuvo un efecto positivo en la extracción de D-xilosa y en la cantidad de ácido utilizado. Las condiciones óptimas fueron 50 g de sólidos (relación sólido/ líquido 1/6) y concentración de ácido sulfúrico 0,016 M. Bajo estas condiciones, el rendimiento de D-xilosa predicho, expresado en g de azúcar por cada 100 g de huesos de aceituna, fue 20,4 (87,2% del máximo teórico)

Generalized scattering-matrix approach for magneto-optics in periodically patterned multilayer systems

We present here a generalization of the scattering-matrix approach for the description of the propagation of electromagnetic waves in nanostructured magneto-optical systems. Our formalism allows us to describe all the key magneto-optical effects in any configuration in periodically patterned multilayer structures. The method can also be applied to describe periodic multilayer systems comprising materials with any type of optical anisotropy. We illustrate the method with the analysis of a recent experiment in which the transverse magneto-optical Kerr effect was measured in a Fe film with a periodic array of subwavelength circular holes. We show, in agreement with the experiments, that the excitation of surface plasmon polaritons in this system leads to a resonant enhancement of the transverse magneto-optical Kerr effect.Comment: 12 pages, 6 figures, submitted to Physical Review

Fundamental limitations in the purifications of tensor networks

We show a fundamental limitation in the description of quantum many-body mixed states with tensor networks in purification form. Namely, we show that there exist mixed states which can be represented as a translationally invariant (TI) matrix product density operator (MPDO) valid for all system sizes, but for which there does not exist a TI purification valid for all system sizes. The proof is based on an undecidable problem and on the uniqueness of canonical forms of matrix product states. The result also holds for classical states.Comment: v1: 11 pages, 1 figure. v2: very minor changes. About to appear in Journal of Mathematical Physic

Low X-Ray Luminosity Galaxy Clusters: Main goals, sample selection, photometric and spectroscopic observations

We present the study of nineteen low X-ray luminosity galaxy clusters (L$_X \sim$ 0.5--45 $\times$ $10^{43}$ erg s$^{-1}$), selected from the ROSAT Position Sensitive Proportional Counters (PSPC) Pointed Observations (Vikhlinin et al. 1998) and the revised version of Mullis et al. (2003) in the redshift range of 0.16 to 0.7. This is the introductory paper of a series presenting the sample selection, photometric and spectroscopic observations and data reduction. Photometric data in different passbands were taken for eight galaxy clusters at Las Campanas Observatory; three clusters at Cerro Tololo Interamerican Observatory; and eight clusters at the Gemini Observatory. Spectroscopic data were collected for only four galaxy clusters using Gemini telescopes. With the photometry, the galaxies were defined based on the star-galaxy separation taking into account photometric parameters. For each galaxy cluster, the catalogues contain the PSF and aperture magnitudes of galaxies within the 90\% completeness limit. They are used together with structural parameters to study the galaxy morphology and to estimate photometric redshifts. With the spectroscopy, the derived galaxy velocity dispersion of our clusters ranged from 507 km~s$^{-1}$ for [VMF98]022 to 775 km~s$^{-1}$ for [VMF98]097 with signs of substructure. Cluster membership has been extensively discussed taking into account spectroscopic and photometric redshift estimates. In this sense, members are the galaxies within a projected radius of 0.75 Mpc from the X-ray mission peak and with cluster centric velocities smaller than the cluster velocity dispersion or 6000 km~s$^{-1}$, respectively. These results will be used in forthcoming papers to study, among the main topics, the red cluster sequence, blue cloud and green populations; the galaxy luminosity function and cluster dynamics.Comment: 13 pages, 6 tables, 9 figures. Uses emulateapj. Accepted for publication in The Astronomical Journal. Some formatting errors fixe

Observation of a hole-size-dependent energy shift of the surface-plasmon resonance in Ni antidot thin films

© 2015 AIP Publishing LLC. A combined experimental and theoretical study of the magneto-optic properties of a series of nickel antidot thin films is presented. The hole diameter varies from 869 down to 636 nm, while the lattice periodicity is fixed at 920 nm. This results in an overall increase of the polar Kerr rotation with decreasing hole diameter due to the increasing surface coverage with nickel. In addition, at photon energies of 2.7 and 3.3 eV, where surface-plasmon excitations are expected, we observe distinct features in the polar Kerr rotation not present in continuous nickel films. The spectral position of the peaks exhibits a red shift with decreasing hole size. This is explained within the context of an effective medium theory by a change in the effective dielectric function of the Ni thin films.H.F. gratefully acknowledges China Scholarship Council (CSC) for financial support and André Schirmeisen for the data of Ni film. A.G.-M. and B.C. acknowledge funding from Spanish Ministry of Economy and Competitiveness through grants “FUNCOAT” CONSOLIDER CSD2008-00023 and “MAPS” MAT2011-29194-C02-01. J.C.C. acknowledges financial support from the Spanish Ministry of Economy and Competitiveness (Contract No. FIS2011-28851-C02-01) and from the Comunidad de Madrid (Contract No. S2013/MIT-2740). E.M.A. and M.G. acknowledge financial support by the European Union under the project CosmoPHOS with the number “3100337”.Peer Reviewe

Observation of a hole-size-dependent energy shift of the surface-plasmon resonance in Ni antidot thin films

A combined experimental and theoretical study of the magneto-optic properties of a series of nickel antidot thin films is presented. The hole diameter varies from 869 down to 636 nm, while the lattice periodicity is fixed at 920 nm. This results in an overall increase of the polar Kerr rotation with decreasing hole diameter due to the increasing surface coverage with nickel. In addition, at photon energies of 2.7 and 3.3 eV, where surface-plasmon excitations are expected, we observe distinct features in the polar Kerr rotation not present in continuous nickel films. The spectral position of the peaks exhibits a red shift with decreasing hole size. This is explained within the context of an effective medium theory by a change in the effective dielectric function of the Ni thin filmsH.F. gratefully acknowledges China Scholarship Council (CSC) for financial support and André Schirmeisen for the data of Ni film. A.G.-M. and B.C. acknowledge funding from Spanish Ministry of Economy and Competitiveness through grants “FUNCOAT” CONSOLIDER CSD2008-00023 and “MAPS” MAT2011-29194-C02-01. J.C.C. acknowledges financial support from the Spanish Ministry of Economy and Competitiveness (Contract No. FIS2011-28851-C02-01) and from the Comunidad de Madrid (Contract No. S2013/MIT- 2740). E.M.A. and M.G. acknowledge financial support by the European Union under the project CosmoPHOS with the number “310337

A Molecular Platinum Cluster Junction: A Single-Molecule Switch

We present a theoretical study of the electronic transport through single-molecule junctions incorporating a Pt6 metal cluster bound within an organic framework. We show that the insertion of this molecule between a pair of electrodes leads to a fully atomically engineered nano-metallic device with high conductance at the Fermi level and two sequential high on/off switching states. The origin of this property can be traced back to the existence of a HOMO which consists of two degenerate and asymmetric orbitals, lying close in energy to the Fermi level of the metallic leads. Their degeneracy is broken when the molecule is contacted to the leads, giving rise to two resonances which become pinned close to the Fermi level and display destructive interference.Comment: 4 pages, 4 figures. Reprinted (adapted) with permission from J. Am. Chem. Soc., 2013, 135 (6), 2052. Copyright 2013 American Chemical Societ

New uses of treated urban waste digestates on stimulation of hydroponically grown tomato (Solanum lycopersicon L.)

One strategy to re-use solid urban wastes is the production of energy by anaerobic digestion. This process also generates high volume of digestates, which are frequently disposal in landfills. The aim of this work is to assess anaerobic digestates as agricultural inputs. Three different biomethanation wastes from different plants were collected. Firstly, a complete physico-chemical characterization of the wastes was done according to the Spanish regulation, showing that the materials had the 90% of the particles below 25 mm, high values of pH, electric conductivity, organic matter, humic acids and soluble nutrients such as NO3−, SO42−, Ca2+, Mg2+, PO43− and K+. Total concentrations of heavy metals and microbiological parameters were below the threshold levels allowed for agricultural use. The wastes were then treated with a strong acid and a strong base having two different solutions (ATr and BTr, respectively) which were evaluated as biostimulants for tomato plants in hydroponic culture. Those liquid extracts, ATr and BTr, demonstrated their biostimulant ability towards root system of tomato enhancing the hair root density and plant biometric parameters including plants weight and chlorophyll content. This work demonstrates the re-use feasibility of treated digestates in agriculture as fertilizers and more over as feedstock for biostimulants productio