In the direct current mode (DC), widely used in electroflocculation (EC), the formation of an impermeable oxide layer on the cathode causes the declining of the efficiency of this process. This disadvantage has been reduced by adopting alternating current (AC). In this study, the effects of AC and DC on operational parameters such as the removal of oils and greases (O&G), color and turbidity from oil-in-water (O/W) emulsions of the petroleum industry using aluminum electrodes were investigated. Removal efficiencies of 95%, 97% and 99% of O&G, color and turbidity with energy consumption of 0.280 kWh/m³ and electrode consumption of 0.12 g and 0.18 g were achieved at a current density of 3 A, operation time of 3 minutes and initial pH of 9.0 using AC and DC, respectively. In continuous flow tests performed with the same experimental conditions, the electrode consumption at times up to 60 minutes were 1.6 g and 3.4 g using AC and DC, respectively.

A highly permeable composite hollow-fibre membrane developed for air separation was used in a membrane aerated biofilm reactor (MABR). The composite membrane consisted of a porous support layer covered with a thin dense film, which was responsible for oxygen enrichment of the permeate stream. Besides oxygen enrichment capability, dense membranes overcome major operational problems that occur when using porous membranes for oxygen transfer to biofilms. Air flow rate and oxygen partial pressure inside the fibres were the variables used to adjust the oxygen transfer rate. The membrane aerated biofilm reactor was operated with hydraulic retention times (HRT) ranging from 1 to 4 hours. High organic load removal rates, like 6.5 kg.m-3.d-1, were achieved due to oxygen transfer rates as high as 107 kg.m-3.d-1. High COD removals, with improved oxygen transfer efficiency, indicate that a MABR is a compact alternative to the conventional activated sludge process and that the selected membrane is suitable for further applications.

The EUV photoionizing radiation and FUV dissociating radiation from newly born stars photoevaporate their parental neutral cloud, leading to the formation of dense clumps that could eventually form additional stars. We study the effects of including a photodissociating FUV flux in models of the fragmentation of a photoevaporating, self-gravitating molecular cloud. We compute 3D simulations of the interaction of an inhomogeneous, neutral, self-gravitating cloud with external EUV and FUV radiation fields, and calculate the number of collapsing clumps and their mass. We find that the presence of an outer photodissociation region has an important effect on the formation of dense structures due to the expansion of an HII region. In particular, including a FUV field leads to the earlier formation of a larger number of dense clumps, which might lead to the formation of more stars.

La radiación fotoionizante EUV y la radiación fotodisociante FUV de estrellas nacientes fotoevaporan la nube donde nacen, llevando a la formación de grumos densos que eventualmente podrían formar estrellas adicionales. Estudiamos los efectos de incluir un flujo fotodisociante FUV, en modelos de fragmentación de una nube molecular fotoevaporada y autogravitante. Llevamos a cabo simulaciones 3D de la interacción de una nube inhomogénea, neutra y autogravitante, con una radiación externa de campos EUV y FUV, y calculamos el número y la masa de los grumos que están en colapso. Encontramos que la presencia de una región de fotodisociación entre la región HII y la nube molecular tiene un efecto importante en la formación de estructuras densas debido a la expansión de una región HII. En particular, incluir un campo FUV lleva a una formación más temprana de un número mayor de grumos densos, los cuales podrían llevar a la formación de un número mayor de estrellas.

We present 3D numerical simulations of photo-evaporation of a binary accretion disk system inside an H II region. The simulations take into account far-and extreme-ultraviolet (FUV and EUV) radiation from a stellar source. We study both FUV dominated and EUV dominated models. FUV dominated models show a well defined interproplyd shell in both Ha emission and density maps, when the separation of the binary system is relatively large (~ 2 000 AU). For smaller separations (<img border=0 src="../../../../../img/revistas/rmaa/v46n1/a8s1.jpg"> 200 AU), the interproplyd shell no longer develops. We show that an EUV model with a suitable choice of parameters increases the Ha emission of the interproplyd shell relative to the emission of the ionization fronts, in better agreement with the observations of the binary proplyd LV1.

Presentamos simulaciones 3D de la fotoevaporacion de un sistema binario de discos de acreción dentro de una región fotoionizada. Las simulaciones consideran la radiación utravioleta lejana y extrema (FUV y EUV) de una estrella. Estudiamos dos casos: modelos dominados por la radiación FUV y por la EUV. Los modelos dominados por la radiación FUV muestran una cascara inter-proplyd que está bien definida tanto en mapas de densidad como de emisión Ha cuando la separación de la binaria es relativamente grande (~ 2 000 AU). Para separaciones menores (<img border=0 src="../../../../../img/revistas/rmaa/v46n1/a8s1.jpg"> 200 AU), no se desarrolla una cascara inter-proplyd. Mostramos que un modelo EUV con una elección de parámetros adecuada tiene una cascara inter-proplyd con una emisión de Ha incrementada respecto a la emisión de los frentes de ionización, en mejor acuerdo con las observaciones del proplyd binario LV1.

This work reports on the viability of the electroflocculation (EF) process for chemical oxygen demand (COD), turbidity and color removal from a raw effluent originated from a particular textile industry related to hemp manufacture. Firstly, the following operational parameters were optimized: current density; initial pH; electrolysis time; material of the electrode (iron, aluminum or iron-aluminum); and interelectrode distance. Additionally, the effects of these parameters on specific electrical energy consumption (SEEC) were studied under the optimum conditions. The best removal efficiencies obtained were 93% for color, 99% for turbidity and up to 87% for COD using an aluminum electrode, the initial pH was 5, the cell time operation was 30 min and current density was 15 A/m². These results indicate that, under the studied operational conditions, electroflocculation of these efluents may constitute a viable alternative for COD, turbidity and color removal.

Neutral clumps immersed in H II regions are frequently found in star formation regions. We investigate here the formation of tails of neutral gas, which are not reached by the direct ionizing flux coming from two massive stars, using both an analytical approximation that allows us to estimate the shadow geometry behind the clumps for different initial geometric configurations, and three-dimensional numerical simulations. We find a good agreement between both approaches to this theoretically interesting problem. A particularly important application could be the proplyds that are found in the Trapezium cluster in Orion, which are being photoevaporated primordially by the O θ1 Ori C y θ2 Ori A.

Glóbulos neutros sumergidos en regiones H II se encuentran frecuentemente en regiones de formación estelar. En este trabajo investigamos la formación de regiones de sombra detrás de glóbulos neutros iluminados por el flujo ionizante directo de dos estrellas. Utilizamos una aproximación analítica, la cual nos permite hacer estimaciones de la geometríca de las sombras detrás de los glóbulos neutros para distintas configuraciones geométricas iniciales, y también simulaciones numéricas tridimensionales. Encontramos un buen acuerdo entre los cálculos analíticos y los numéricos. Una aplicación de particular relevancia pueden ser los 'proplyds' ubicados en el cúmulo del Trapecio en Orión, los cuales están siendo fotoevaporados por la radiación de las estrellas O θ¹ Ori C y θ² Ori A.

As amiotrofias espinhais progressivas (SMAs) constituem as doenças degenerativas de origem genética letais mais comuns do sistema nervoso central e mais freqüentes dentre as doenças autossômicas recessivas após a mucoviscidose. A incidência estimada das SMAs é de aproximadamente 1:10.000 nativivos. Clinicamente, as SMAs são classificadas em mais grave (doença de Werdnig-Hoffmann, tipo I), intermediária (tipo II) e tardia e benigna (doença de Kugelberg-Welander, tipo III). O gene para os três tipos de SMAs foi mapeado no cromossomo 5 q11.2-13.3. Foram identificados dois genes candidatos na mesma região: SMN (sobrevida do neurônio motor) e NAIP (proteína inibidora de apoptose neuronal). Estudamos ambos genes em 87 pacientes brasileiros (20 tipo I,14 tipo II e 53 tipo III) pertencentes a 74 famílias, utilizando as técnicas de PCR e SSCP. Foi encontrada deleção nos exons 7 e/ou 8 do gene SMN em 69% das famílias: 16/20 na tipo I, 9/12 na tipo II e 26/42 na tipo III. Dentre as 51 famílias com deleção, 44 tiveram deleção nos exons 7 e 8 enquanto 7 tiveram deleção somente no exon 7. Deleção no exon 5 do gene NAIP foi encontrada em 7/20 na tipo I, 2/12 na tipo II e 1/42 na tipo III. Não foi encontrada deleção nos genes SMN e NAIP nos 112 progenitores, 26 irmandades assintomáticas e 104 controles normais. Não houve correlação entre deleção de um ou ambos genes com a gravidade do quadro clínico.

Spinal muscular atrophy (SMA), the second most common lethal autosomal recessive disorder, has an incidence of 1:10,000 newborns. SMA is divided into acute (Werdnig-Hoffmann disease, type I), intermediate (type II) and juvenile forms (Kugelberg-Welander disease, type III). The gene of all three forms of SMA maps to chromosome 5q 11.2-13.3. Two candidate genes, the survival motor neuron (SMN) gene and the neuronal apoptosis inhibitory protein (NAIP) gene, have been identified; SMN is deleted in most SMA patients. We studied both genes in 87 Brazilian SMA patients (20 type I, 14 type II and 53 type III) from 74 unrelated families, by using PCR and single strand conformation polymorphism (SSCP). Deletions of exons 7 and/or 8 of the SMN gene were found in 69% of the families: 16/20 in type I, 9/12 in type II and 26/42 in type III. Among 51 families with deletions, 44 had both exons deleted while seven had deletions only of exon 7. Deletions of exon 5 of the NAIP gene were found in 7/20 of type I, 2/12 of type II and 1/42 of type III patients. No deletion of SMN and NAIP genes was found in 112 parents, 26 unaffected sibs and 104 normal controls. No correlation between deletions of one or both genes and phenotype severity was found.