Use of talc to control problems associated with dissolved and colloidal material in papermaking

Increasingly stringent environmental standards and market demands are forcing pulp and paper mills to minimize both their water usage and their effluent discharge. Higher rates of process water reuse in pulp and paper mills leads to increased amounts of dissolved and colloidal substances in the process water, which is a major factor limiting further closure of the water circuits. This study explores the use of different types of talcs as control agents for dissolved and colloidal material contained in white water from paper mills using recovered and coated paper as raw materials. It also identifies the kinds of talcs that can be used to control detrimental properties of the white water

Activated sludge response to detergent spill in sewage

Motivation: The aim of this study is to determine the response of activated sludge microorganisms to detergent spill events that occurs sporadically in the Wastewater Treatment Plants (WWTPs). This detergent spill can cause loss of floccular structures and the disappearance of part of the microbiota constituent of the mixed liquor. Methods: The pilot plant used for the study consists of four series-connected lagoons, with aeration systems in three of them, and a feed tank of 25L. The lagoon stabilization process allows the generation and maturation of activated sludge necessary for wastewater treatment. The mixed liquor was sampled to identify its functional groups present in the water allowing a later comparative after applying detergent. Four spills in total, based on Sodium Dodecyl Sulfate (SDS) were carried out and its effects studied. Results: Observations showed the existence of floccular structures of remarkable resistance of as well as the presence of  many functional groups of microorganisms in the detergent spills up to 37,5mg/l. Higher spills from 60mg/l to 120mg/l increase floccular damages and microbiota mortality. It was observed a proliferation of filamentous bacteria Beggiatoa on the surface of activated sludge after spills, as well as Paramecium association to it. Conclusions: Lagooning system seems to respond well to detergent discharges lower than 40mg / l SDS, keeping floccular structures very compacts and the presence of groups of microorganisms. Discharges of 60mg / l to 120mg / l significantly increase the mortality rate of activated sludge microbiota and the loss of structure at the floc, especially in the first two ponds. The system seems to cushion the spills in the first ponds reducing further damage in rear lagoons. The third lagoon had the highest average number of individuals per milliliter that can be due to a lower impact by detergent spills and the contribution of aeration system. Beggiatoa proliferation could be motivated by an oxygen descent in lagoons associated to detergent discharges

Cartography, petrology and geochemistry of Cerro Mogabar_pluton, batholith of Los Pedroches (Córdoba, Spain)

[Resumen ]El plutón del Cerro Mogábar forma parte de la asociaci6n magmática del batolito de Los Pedroches. Está constituido por adamellitas porfídicas de grano fino, granitos porfídicos de grano grueso y leucogranitos; el conjunto ígneo se completa con un cortejo filoniano, compuesto básicamente por diques de composición granítica, aplitas, pegmatitas y diques de cuarzo.Las rocas que componen el plutón del Cerro Mogábar, son el extremo aluminoso de una asociaci6n alumínico-cafémica, de tendencia calcoalcalina (o granodiorítica), que evoluciona desde términos ranodioríticos (plutón granodiorítico de Los Pedroches) hasta términos leucograníticos. La asociación aluminico-cafémica calco-alcalina, integra, en una única serie de diferenciaci6n, a los grupos de rocas mayoritarios que componen el batolito de Los Pedroches.[Abstract] The Cerro Mogábar pluton forms a part of Los Pedroches Batholith magmatic association. It is constituted by fine-grained, porphyritic adamellite, coarsegrained porphyritic granite and leucogranites. This igneous ensemble is completed with a mainly granitic dyke swarm, aplites, pegmatites and quartz veins. Rocks from the Mogábar pluton are the aluminous of an aluminic-cafemic association of calcalkaline (or granodioritic) affinities which evolves from granodiorite to leucogranitic terms. The alumino-cafemic, calcalkaline association integrates within a single differentiation series the main rocks which compound Los Pedroches Batholit

Mapping the Wigner distribution function of the Morse oscillator into a semi-classical distribution function

The mapping of the Wigner distribution function (WDF) for a given bound-state onto a semiclassical distribution function (SDF) satisfying the Liouville equation introduced previously by us is applied to the ground state of the Morse oscillator. Here we give results showing that the SDF gets closer to the corresponding WDF as the number of levels of the Morse oscillator increases. We find that for a Morse oscillator with one level only, the agreement between the WDF and the mapped SDF is very poor but for a Morse oscillator of ten levels it becomes satisfactory.Comment: Revtex, 27 pages including 13 eps figure

Characterisation of agricultural residues used as a source of fibres for fibre-cement production

Nowadays, certain components of non-wood annual plants such as corn stalk and industrial hemp core are considered waste materials or used in low value applications; both by-products have a very low cost. On the other hand, given the large quantities of these materials generated worldwide and their renewable character, it is reasonable to explore new routes for their exploitation. The aim of this paper is to study the potential of both corn stalk (Zea Mays L.) and industrial hemp core (Cannabis Sativa L.) fibres as a renewable source of cellulose fibres in the production of fibre-cement. For each source of fibres, a number of chemical cooking treatments were studied. The morphological properties of the fibres were determined using a scanning electron microscope and a fibre and pulp morphological analyser. Pulp refining was carried out in a PFI mill to improve the characteristics of the fibres. In the case of corn fibres, different degrees of refining were applied. The fibre flocculation process was investigated using several polyacrylamides. The process was studied by monitoring the chord size distribution in real time by means of a focused beam reflectance measurement probe. The results indicated both pulps can be used for the production of fibre-cement, having the two types of pulp morphological similarities with the pine fibres currently used. Through the flocculation process it was concluded the floc size depends on the length of the fibres

Two-dimensional carrier density distribution inside a high power tapered laser diode

The spontaneous emission of a GaAs-based tapered laser diode emitting at lambda = 1060 nm was measured through a window in the transparent substrate in order to study the carrier density distribution inside the device. It is shown that the tapered geometry is responsible for nonuniform amplification of the spontaneous/stimulated emission which in turn influences the spatial distribution of the carriers starting from below threshold. The carrier density does not clamp at the lasing threshold and above it the device shows lateral spatial hole-burning caused by high stimulated emission along the cavity center. (C) 2011 American Institute of Physics. (doi: 10.1063/1.3596445

Simulation of high brightness tapered lasers

Tapered semiconductor lasers have demonstrated both high power and good beam quality, and are of primary interest for those applications demanding high brightness optical sources. The complex non-linear interaction between the optical field and the active material requires accurate numerical simulations to improve the device design and to understand the underlying physics. In this work we present results on the design and simulation of tapered lasers by means of a Quasi- 3D steady-state single-frequency model. The results are compared with experiments on Al-free active region devices emitting at 1060 nm. The performance of devices based on symmetric and asymmetric epitaxial designs is compared and the influence of the design on the beam properties is analyzed. The role of thermal effects on the beam properties is experimentally characterized and analyzed by means of the numerical simulations. Tapered lasers with separate electrical contacts in the straight and tapered sections, based on symmetrical and asymmetrical epitaxial designs are also presented and analyze

Optimizing polymer lab-on-chip platforms for ultrasonic manipulation: Influence of the substrate

The choice of substrate material in a chip that combines ultrasound with microfluidics for handling biological and synthetic microparticles can have a profound effect on the performance of the device. This is due to the high surface-to-volume ratio that exists within such small structures and acquires particular relevance in polymer-based resonators with 3D standing waves. This paper presents three chips developed to perform particle flow-through separation by ultrasound based on a polymeric SU-8 layer containing channelization over three different substrates: Polymethyl methacrylate (PMMA); Pyrex; and a cracked PMMA composite-like structure. Through direct observations of polystyrene microbeads inside the channel, the three checked chips exhibit their potential as disposable continuous concentration devices with different spatial pressure patterns at frequencies of resonance close to 1 Mhz. Chips with Pyrex and cracked PMMA substrates show restrictions on the number of pressure nodes established in the channel associated with the inhibition of 3D modes in the solid structure. The glass-substrate chip presents some advantages associated with lower energy requirements to collect particles. According to the results, the use of polymer-based chips with rigid substrates can be advantageous for applications that require short treatment times (clinical tests handling human samples) and low-cost fabrication. © 2015 by the authors; licensee MDPI, Basel, Switzerland.The study has been performed in the framework of two Spanish National Research Project BIO2011-30535-C04-01,02,03, “Development of a high throughput for isolation of tumor cells circulating in peripheral blood”.We acknowledge support by the CSIC Open Access Publication Initiative through its Unit of Information Resources for Research (URICI).Peer Reviewe

Collisional Semiclassical Aproximations in Phase-Space Representation

The Gaussian Wave-Packet phase-space representation is used to show that the expansion in powers of $\hbar$ of the quantum Liouville propagator leads, in the zeroth order term, to results close to those obtained in the statistical quasiclassical method of Lee and Scully in the Weyl-Wigner picture. It is also verified that propagating the Wigner distribution along the classical trajectories the amount of error is less than that coming from propagating the Gaussian distribution along classical trajectories.Comment: 20 pages, REVTEX, no figures, 3 tables include

Estrategias metodológicas para el aprendizaje basado en proyectos de investigación en Ingeniería de Bioprocesos

El desarrollo de métodos interactivos que propician el intercambio de información entre el alumnado y profesorado ha significado un esfuerzo importante para ambos, ya que rompen con el estrecho espacio formativo que deja la clásica transmisión mecánica y verbalista de conocimientos. Marcando como objetivo la superación del 'argumento de autoridad', se han propuesto diversas estrategias para llevar a cabo procesos de aprendizaje basados en investigación. En el presente estudio se hace un recorrido por los diversos métodos interactivos de enseñanza- aprendizaje haciendo especial hincapié en las estrategias metodológicas del aprendizaje basado en proyectos experimentales debido a su especial relevancia en el ámbito científico. Se propone un método de preselección por parte del alumnado así como cuatro fases principales para llevar a cabo un trabajo de investigación de calidad. La primera fase consiste en una propuesta inicial en la que se ofertan al alumnado los proyectos a elegir por el grupo ECOWAL para realizar el trabajo fin de Máster y en la que el alumnado debe construir una base documental o ¿estado del arte¿. Durante la segunda fase o ¿diseño de la investigación¿ se marcan unos objetivos claros y se diseña el trabajo experimental a realizar. Seguidamente, se propone una tercera fase de recogida y tratamiento de datos y se detalla especialmente cómo realizar el informe con el que concluye la cuarta fase. Los intercambios de ideas, los apoyos que se prestan tanto entre iguales, así como las aportaciones procedentes del docente u otro colaborador, hacen de este sistema un tejido cultural compartido excelente para el aprendizaje del alumnado en el campo de la Ingeniería Química.Artículo revisado por pare