Short time tempering has been applied to steels to improve toughness keeping the hardness at the same level. For AISI D2 tool steel, typical thermal cycles are quench and temper. The austenitizing temperature is around 1040 ºC and the subsequent double tempering at temperatures close to 500 ºC, for 2 hours each, in order to get the maximum secondary hardness. The aim of the present work is to verify the effects of short time tempering in the AISI D2. For such purpose the Hollomon-Jaffe tempering parameter was used to determine the equivalent time at 600 and 700 °C, being 500 °C for 2 hours the standard temperature and time. The thermal cycles were carried out at a dilatometer. All the specimens were austenitized at 1040 °C followed by double tempering at: 500 and 700 °C for 2 hours each; and 500 °C, 600 °C, and 700 °C for 10 s and 1 min each. The dilatometric curves were analysed. Scanning electron microscopy, X-ray diffraction and Vickers hardness were carried out to characterize the microstructure and mechanical properties. The short time tempering conducted at high temperatures led to the formation and growth of tempering carbides and to matrix recrystallization, which were responsible for greatly reducing the hardness of the material. The short time tempering up to the intermediate temperature of 600 ºC, for 1 minute or 10 seconds, produced results like the conventional tempering in microstructural and hardness terms, denoting that the Hollomon-Jaffe tempering parameter predictability close to the secondary hardness peak. level D steel temper 104 50 each HollomonJaffe Hollomon Jaffe 60 70 C dilatometer analysed microscopy Xray X ray properties recrystallization material seconds terms peak 5 6 7

Resumo Introdução A fibrina rica em plaquetas (FRP) é formada por um concentrado sanguíneo autólogo, com propriedades de promover a proliferação celular, regeneração de tecido, dentre eles tecido ósseo, gengival e epitelial. Objetivo Comparar quatro tipos diferentes de processamento e obtenção de FRP, analisando a sua formação através de técnicas laboratoriais. A finalidade do estudo é validar um método que obtenha maior qualidade para o uso em cirurgias nas diversas áreas da odontologia. Material e método O experimento foi constituído de uma coleta de sangue de 12 voluntários, onde a amostra de cada paciente foi processada de 4 formas. A análise dos processamentos se deu em duas etapas, onde na primeira, quantitativa, foi analisado o plasma pobre em plaquetas (PPP), através de contagem de constituintes sanguíneos em câmara de Neubauer. Na segunda etapa, qualitativa, foram analisadas as FRP em microscopia através de lâminas histológicas. Resultado A análise estatística da contagem de leucócitos, hemácias e plaquetas não mostraram diferença significativa entre os distintos processamentos. As análises histológicas do FRP mostraram redes de fibrina com agregação plaquetária, inúmeros leucócitos e presença de hemácias, sendo que as amostras de dupla centrifugação apresentaram mais leucócitos que nas demais. Conclusão Dos procedimentos analisados, a amostra centrifugada a 1 única vez a 3000 RPM (1900 G) por 10 min mostrou-se a melhor qualidade de FRP.

Abstract Introduction Platelet-rich fibrin (PRF) is formed by an autologous blood concentrate, with properties that promote cell proliferation and regenerationof bone, gingival and epithelial tissue. Objective To compare four different procedures for processing as well as obtaining PRF, and analyzing their formation through laboratory techniques. The purpose of the study is to validate a method that produces higher quality PRF for oral surgery use in different branches of dentistry. Material and method The experiment consisted of collecting blood from 12 volunteers, and processing each patient’s sample in 4 different ways. In the following two-stage process analysis, the first, quantitative, step was to analyze the samples' platelet-poor plasma (PPP),with a Neubauer Hemocytometer to count blood components. In the second, qualitative step, the sample’s PRF were analyzed under microscopy using histological slides. Result The statistical analysis of the leukocyte, red blood cell and platelet count did not show any significant distinction when comparing different processes. Histological analysis of the PRF showed fibrin network with platelet aggregation, several leukocytes and presence of red blood cells, with double centrifuged samples presenting more white blood cells than the others. Conclusion: Among the analyzed procedures, the sample centrifuged once at 3000 RPM (1900 G) for 10 min showed the best quality PRF.

Resumen La prevalencia de diabetes mellitus se incrementa en todo el mundo alcanzando a 592 millones de diabéticos el año 2035; así mismo la OMS proyecta que las muertes por diabetes se dupliquen entre los años 2005 y 2030 (OMS, 2016). En Bolivia la medicina tradicional reporta plantas medicinales a las cuales se les ha atribuido propiedades hipoglucemiantes, sin embargo en muchos casos no existen estudios científicos que avalen dichas propiedades. Este estudio se ha realizado con la finalidad de evaluar el efecto de los granos de Amaranthus caudatus (amaranto), Linum usitatissimum (Linaza) y Lupinus mutabilis (tarwi) sobre la hiperglicemia inducida por aloxano en animales de experimentación. Se administró por vía oral a ratones con hiperglicemia (glicemia > 180,6 mg/dl) una dosis de 2000 mg/kg de peso corporal de cada extracto hidro-etanólico obtenido de los granos de A. caudatus, L. usitatissimum y L. mutabilis. Los niveles de glucosa fueron medidos antes y después de la administración de los extractos. Los extractos hidro-etanolicos disminuyeron de forma significativa (p<0.05) la glucosa plasmática a las cuatro y dos horas después de su administración. El extracto de A. caudatus disminuyo la glucosa plasmática de 380 mg/dl a 260 mg/dl, el extracto de L. mutabilis disminuyo la glucosa plasmática de 310 mg/dl a 167 mg/dl, y el extracto de L. usitatissimum disminuyo la glucosa plasmática de 210,57 mg/dl a 168,14 mg/dl. Siendo el extracto de L. mutabilis el que presento mayor actividad sobre la hiperglicemia inducida por aloxano.

Abstract The prevalence of diabetes mellitus increases worldwide reaching 592 million diabetics in 2035; Likewise, the WHO projects that deaths due to diabetes double between the years 2005 and 2030 (WHO, 2016). In Bolivia, traditional medicine reports medicinal plants to which hypoglycaemic properties have been attributed, however in many cases there are no scientific studies to support these properties. This study was carried out with the purpose of evaluating the effect of Amaranthus caudatus (amaranth), Linum usitatissimum (Linseed) and Lupinus mutabilis (tarwi) on the hyperglycemia induced by alloxan in experimental animals. Mice with hyperglycemia (glycemia>10 mmol/L) were administered a dose of 2000 mg/kg body weight orally of each hydro-ethanolic extract obtained from the grains of A. caudatus, L. usitatissimum and L. mutabilis. Glucose levels were measured before and after the administration of the extracts. The hydro-ethanol extracts significantly decreased (p <0.05) the plasma glucose at four and two hours after its administration. The extract of A. caudatus decreased the plasma glucose from 380 mg / dl to 260 mg / dl, the extract of L. mutabilis decreased the plasma glucose from 310 mg / dl to 167 mg / dl, and the extract of L. usitatissimum decreased Plasma glucose from 210.57 mg / dl to 168.14 mg / dl. The extract of L. mutabilis was the one with the highest activity on the hyperglycemia induced by alloxan.

Resumo A proposição deste estudo foi avaliar o pH, solubilidade e ação antimicrobiana da pasta de Hidróxido de Cálcio (HC), Pasta Diantibiótica (metronidazol+ciprofloxacina-DAP), Hidróxido de Cálcio adicionado a DAP (HC/DAP) e pasta Triantibiótica (metronidazol + ciprofloxacina + miociclina - TAP). a medição do pH e liberação de íons cálcio (n=10) foram avaliadas através de peagômetro e espectofotômetro de absorção atômica. Canais de dentes de acrílico (n=10) foram preenchidos com as medicações de canal mencionadas, imersos em água ultrapura e a solubilidade foi aferida pela diferença entre o volume inicial e final (7,15 e 30 dias) usando micro tomografia computadorizada. O biofilme de Enterococcus faecalis foi induzido em blocos de dentina bovina (n=20) e tratados com as pastas em questão por 7 dias. A porcentagem de bactérias vivas foi verificada usando o microscópio confocal com corante LIVE/DEAD. HC e HC/DAP apresentaram os maiores valores de pH e liberação de íons cálcio. A respeito da solubilidade, depois de 7 dias, os grupos com pastas antibióticas apresentaram perda de volume significante. HC e HC/DAP não tiveram diferenças estatísticas com o grupo controle na ação antimicrobiana contra biofilme. No entanto, a TAP e a DAP mostraram porcentagem significante de redução bacteriana. Conclusões: Devido à alta solubilidade das pastas, renovar as medicações antibióticas a cada 7 dias ou usa-las por esse período em protocolos regenerativos é recomendado. DAP é indicada para matar E. faecalis na forma de biofilme porque tem ação antimicrobiana similar a TAP. A adição do CH à DAP reduz significantemente sua ação antimicrobiana. Apesar da baixa solubilidade e altos valores de pH, a pasta de CH apresenta baixa ação antimicrobiana contra E. faecalis em biofilme.

Abstract: The purpose of this study was to evaluate the pH, solubility and antimicrobial action of Calcium Hydroxide Paste (CH), Double Antibiotic Paste (metronidazole+ciprofloxacin-DAP), calcium hydroxide added to DAP (CH/DAP) and Triple Antibiotic Paste (metronidazole + ciprofloxacin+minocycline-TAP). pH (n=10) were measured by pHmeter. Root canals of acrylic teeth (n=10) were filled with the above-mentioned intracanal-dressings, immersed in ultrapure water, and solubility was measured by the difference between the initial and final volume (7,15 and 30 days) by using micro-computed tomography. Enterococcus faecalis biofilm was induced on bovine dentin disc surfaces (n=20), and treated with the pastes for 7 days. Percentage bacterial viability was verified by confocal microscope, with LIVE/DEAD dye. CH and CH/DAP presented the highest pH values. Regarding solubility, after 7 days, antibiotic groups presented significant volume loss. CH and CH/DAP showed no statistical difference compared with the Control in antimicrobial action against E. faecalis biofilm. However, TAP and DAP presented a significant percentage reduction in bacterial population. Due to high solubility of the pastes, renewing antibiotic dressings every 7 days, or using the medications for this period in regeneration protocols is recommended. DAP is indicated for killing E. faecalis in biofilm because it has antimicrobial action similar to TAP. Adding Calcium Hydroxide to DAP significantly decreased its antimicrobial action. In spite of its the low solubility and high pH values, the CH paste showed a low level of antimicrobial action against E. faecalis in biofilm.

Abstract The main purpose of this paper is introducing a new method based on the transmission line approach for designing FSS-backed reflecarray antennas. For this reason a dual band reflectarray antenna is designed. This antenna contains a conventional single layer RA and a FSS backed double layer RA with 54% and 50% efficiency operating at X band and K band, respectively. A double layer FSS is used between RAs to isolate them. K band cell element is designed and analyzed using transmission line method and consideration of equivalent circuit for elements of each layer. Then the results obtained using this technique is compared to those found by CST and ADS. The comparison shows a good agreement. Jerusalem cross dipole with variable size is employed as radiation element in both bands. The most important properties of our suggested array are low cross polarization and high efficiency.

Abstract The purpose of this study was to obtain adjusted measures for a Mexican population calculating item discrimination properties, internal consistency and factor structure of four instruments: Zarit Burden Inventory, Maslach Burnout Inventory, the General Health Questionnaire, and Stress Symptoms Inventory. The report presents the results of the analysis of psychometric properties of the four selected measures and used in a study designed to document the effect of objective workloads in Mexican homemakers over perceived workloads, burnout syndrome, general health, and stress symptoms. Seven hundred and fifty nine participants all Mexican homemakers dedicated to at least three hours-a-day to domestic activities were included. Additionally, they were in charge of childrearing, feeding, hygiene, cleaning the house and scheduling home activities; they needed to have basic writing and reading skills. A quote of women participants from five states of Mexico, living in urban or rural zones, with single, double or triple workloads were included to the sample. Estimations included statistical procedures for item discrimination properties sticking to distribution and significant differentiation of variability; internal consistency analysis for estimation of reliability of subscales; exploratory factor analysis to define factorial structure. Finally, it was calculated confirmatory factor analysis to confirm construct validity. Results showed that the instruments have adequate psychometric properties to evaluate samples of Mexican homemakers.

Resumen El propósito de este estudio fue obtener medidas ajustadas a una población mexicana calculando las propiedades de discriminación de reactivos, consistencia interna y estructura factorial de cuatro instrumentos: (a) Escala de Carga Percibida de Zarit (ECP); (b) Inventario de Burnout de Maslach (MBI); (c) la Escala General de Salud (EGS) de Goldberg y Hillier, y (d) Inventario de Sintomatología del Estrés (ISE). El reporte presenta los resultados del análisis de propiedades psicométricas de las cuatro medidas seleccionadas para el estudio del efecto de las cargas objetivas de trabajo en amas de casa mexicanas sobre la carga de trabajo percibido, síndrome de burnout, salud general y síntomas de estrés. Se incluyeron 759 casos de mujeres amas de casa mexicanas que realizaban labores domésticas para la familia al menos tres horas diarias, que fueran responsables de las actividades de crianza, alimentación, higiene, aseo y organización de las labores del hogar y supieran leer y escribir. Se seleccionaron por cuotas mujeres de cinco estados de la República Mexicana, de zona urbana y rural, con jornadas de trabajo únicas, dobles o triples. Se llevaron a cabo los procedimientos de estimación de discriminación de reactivos siguiendo los criterios de distribución y diferenciación significativa de la variabilidad de puntajes; análisis de consistencia interna para confiabilidad de las sub-escalas; análisis factorial exploratorio para definir la estructura factorial de las variables evaluadas y análisis factorial confirmatorio para confirmar validez de constructo. Los resultados muestran los ajustes en los instrumentos utilizados alcanzando propiedades psicométricas adecuadas para evaluar amas de casa.

O objetivo deste trabalho foi avaliar a influência da percepção háptica na estabilidade locomotora do ser humano durante a condução de um cão com uma guia. Adultos (n=14), com e sem restrição da visão, andaram sobre uma trave de equilíbrio sozinhos, ou, com uma guia, andaram conduzindo um cão sobre um banco estreito ao lado. Quando os participantes caminharam conduzindo o cão, privados da visão, o desempenho locomotor-avaliado através da duração do deslocamento total, da duração das passadas, das fases de duplo suporte e balanço, do comprimento e velocidade das passadas, assim como da variabilidade da fase relativa-melhorou significativamente (p < 0,05) em relação ao desempenho locomotor na condição sem o cão. Nas condições com visão, conduzir o cão não resultou em mudanças nestas variáveis. Concluímos que estes indivíduos foram capazes de utilizar a guia do cão para detectar propriedades hápticas com propósito de melhorar a estabilidade na locomoção.

The purpose of this study was to evaluate how walking a dog on a leash influenced haptic perception and stability during human locomotion. Fourteen adults, with and without sight restriction, walked on a narrow balance beam by themselves, or holding a leash attached to a dog that walked on a parallel narrow bench. The performance of participants who walked with the dog, but blindfolded, significantly (p < 0.05) improved as compared to the condition without the dog. Their locomotion performance was assessed via the duration of the total displacement on the balance beam, durations of the double support phase, swing phase, stepping cycle, stepping length, and linear velocity, as well as variability of the inter-limb relative phase. With vision, these parameters were not affected by the presence of the dog. We conclude that these adults were able to use the dog's leash to detect haptic properties in order to achieve postural control (e.g., stability in speed performance) while walking.

El objetivo de este estudio fue evaluar la influencia de la percepción háptica en la estabilidad del aparato locomotor humano, mientras que la conducción de un perro con una guía. Los adultos (n = 14), con y sin restricción de la visión, caminaron sobre una barra de equilibrio solo, o simultáneamente con el perro en la guia en un banco al lado. Cuando participantes caminaron con el perro, privados de vista, el rendimiento locomotor-evaluado por la longitud total de desplazamiento, la longitud de los pasos, las fases de doble apoyo e impulsión, la longitud y la velocidad del pasado, así como la variabilidad de la fase relativa-mejoró significativamente (p < 0.05) en comparación con el rendimiento locomotor en la condición sin el perro. En las condiciones con la visión, impulsar el perro no dio lugar a cambios en estas variables. Llegamos a la conclusión de que estos individuos fueron capaces de utilizar la guía del perro para detectar propiedades hápticas con el propósito de mejorar la estabilidad en la locomoción.

The technological properties of concentrates of sennosides A+B were studied with the purpose to evaluate the feasibility of its processing to the pharmaceutical form of tablets. The studied properties include the compactibility, the ejection pressure, the disintegration time and the rate of the powder flow. The obtained results show that a mixture of microcrystalline cellulose with colloidal silica is a suitable excipient to increase to the double the powder flow rate and 4 times the tablet strength and to reduce in 40 % the time necessary to disintegrate the tablets. The above mentioned formulation modifications do not affect in an important manner the gliding properties of the tablets being ejected from the die where they were compressed.

Se realizó un estudio de las propiedades tecnológicas del polvo de senósidos A+B concentrados con el fin de valorar la factibilidad de su procesamiento en la forma farmacéutica de tabletas. Las características estudiadas incluyen la compactabilidad, la presión de expulsión, el tiempo de desagregación y la velocidad de flujo del polvo. Los resultados obtenidos muestran que una mezcla de celulosa microcristalina tipo 102 con sílica coloidal sería un excipiente adecuado para aumentar hasta el doble la velocidad del flujo del polvo, hasta 4 veces la resistencia a la ruptura de las tabletas y disminuir a la mitad el tiempo necesario para la desagregación de estas. Las modificaciones en la formulación antes mencionadas no afectan de manera importante las propiedades de deslizamiento de las tabletas, al ser expulsadas desde la matriz en que se fabricaron.

Esta investigación tuvo como objetivo realizar un diagnostico técnico del sistema de producción ubicado en una zona de colinas del estado Guárico, Venezuela. Se siguieron los criterios de ubicación geográfica y un número máximo de 150 animales para determinar la muestra, la cual fue de 95 fincas seleccionadas al azar. Como instrumento de recolección de información se utilizó una encuesta que contenía variables socioeconómicas, productivas y de manejo. Se usó estadística descriptiva para el análisis de los datos. Se observó baja proporción de vacas en ordeño (23,6%), sin control de apareamiento, con promedio de 18 vacas por toro, en rebaños mestizos con predominio de reproductores mestizos (47%). La mano de obra más importante es familiar y son escasos los productores que llevan y usan registros. La superficie promedio por finca fue 113,1 ha. La productividad física fue muy baja, con una carga animal de 0,3 UA/ha. El 78,4% de las fincas producen cereales como producto principal, mientras que la producción bovina es un complemento del sistema, siendo la leche extraída por ordeño manual y procesada en forma de queso para su venta. Se encontraron índices productivos bajos que reflejan un escaso uso de tecnología en el sistema, conformado a su vez por una alta variabilidad de fincas que se diferencian en la forma como utilizan los recursos de la zona. Igualmente, se evidenció la alta influencia que sobre el sistema doble propósito tienen cereales como maíz y sorgo, los cuales están estrechamente relacionados por el beneficio alimenticio que tienen sobre los animales del rebaño.

This research aimed to make a diagnosis of the technical production system located in a hilly area of Guarico state, Venezuela. We followed the criteria: of geographic location and a maximum of 150 animals to determine the sample, which was 95 farms selected at random. As a tool for collecting information, a survey containing socio-economic, production, and management variables was utilized. Descriptive statistics were used to analyze the data. It was observed low proportion of milking cows (23.6%), uncontrolled mating, with an average of 18 cows per bull in herds with a predominance of breed and crossbredherd (47%). The most important workforce was the family and a few producers keep and use records. The average farm size was 113.1 ha. The physical productivity was very low, with a stocking rate of 0.3 AU/ha. Farms produced grain as the main product (78.4%), while beef production was a complement system, as the milk being drawn by hand and processed as cheese for sale. We found that low production rates reflect a small use of technology in the system, in turn shaped by a high variability of properties that differ in the way they used local resources. Also, it was shown the high influence on the dual purpose system by cereals, such as maize and sorghum, which are closely linked by the feeding benefit that have on the animals of the herd.

RESUMEN El presente trabajo tiene como objetivo realizar un diagnóstico estructural en 30 fincas de doble propósito en el municipio Alberto Arvelo Torrealba, estado Barinas, Venezuela. Se aplicó la metodología de diagnósticos técnicos, estructurales, funcionales y mejoramiento continuo en los sistemas de producción de leche y carne con vacunos. Los datos se analizaron por métodos estadísticos multivariados, mediante el análisis factorial de correspondencias múltiples y clasificación ascendente jerárquica, contenidos en el paquete estadístico CSTAT. Se consideraron las siguientes variables: ingreso por leche, tiempo de permanencia del productor en la finca, hembras en el rebaño, vacas con mediano grado de herencia europea, becerros con más de ½ de herencia europea, tamaño de la finca, capital de trabajo y la calidad de la leche (acidez). El análisis generó tres modalidades con distintas intensidades de producción de leche: 1) ocho fincas con direccionalidad hacia la producción de carne, definida como doble propósito carne-leche, 2) 18 fincas con direccionalidad para la producción de leche clasificada como doble propósito leche-carne y 3) cuatro fincas tendientes a buscar un equilibrio en la producción de leche y carne ubicadas como doble propósito indefinida. Las variables de mayor contribución para la conformación de las modalidades productivas fueron: 24,50, 17,42, 14,03 y 12,69% para los becerros con herencia europea, hembras en el rebaño, ingreso por leche y capital de trabajo, respectivamente. El estudio mostró que los sistemas de ganadería doble propósito en la zona bajo estudio fueron estructuralmente variantes. Los estudios estructurales son indispensables para el conocimiento en detalle y el establecimiento de bases para fomentar las transformaciones y su mejoramiento continuo

SUMMARY The objective of this work was to carry out a structural diagnostic in 30 raising cattle farms under a double purpose system in the Alberto Arvelo Torrealba municipality, Barinas state in Venezuela. It was applied the methodology of technical, structural, functional diagnoses and continuous improvement in the systems of production of milk and meat with bovine. The data were analyzed by multivariate statistical methods using the factorial analysis of multiple correspondences and the upward hierarchical classification, in the statistical package CSTAT. There were considered the following variables: Income for milk, staying time of the producer in the property, females in the herd, cows with medium grade of European inheritance, calves with more than a half of European inheritance, size of the property, working capital, and the quality of the milk (acidity). The analysis generated three modalities with different intensities of milk production: 1) eight properties with directionality toward the meat production, defined as double purpose meat-milk, 2) eighteen properties with directionality for the production of milk classified as double purpose milk-meat, and 3) four properties with a tendency to look for a balance in the production of milk and meat, identified as indefinite double purpose. The variables with higher contribution for the conformation of the productive were: 24.50, 17.42, 14.03 and 12.69% for the calves with European inheritance, females in the herd, milk and working capital, respectively. The study showed that the systems of double purpose cattle raising in the area under study were structurally variable. The structural studies are indispensable for the knowledge in detail and the establishment of bases to foment the transformations and their continuous improvement

No presente trabalho é estudado o preparo de membranas anisotrópicas compostas, em uma única etapa, para os processos de NF e OI, através do espalhamento simultâneo de duas soluções poliméricas [acetato de celulose - AC/formamida/acetona (26,3/23,7/50 % p/p) e AC/poli(vinil pirrolidona) - PVP/N,N-dimetilformamida - DMF (15/10/75 % p/p)]. A precipitação das soluções, em água destilada, foi acompanhada por medidas de transmitância de luz. Estudou-se a influência das condições de preparo das membranas, na sua morfologia e nas suas propriedades de transporte (fluxo de permeado e retenção de solutos - Polietilenoglicol (PEG) para a NF e NaCl para a OI). Realizou-se também um tratamento térmico nas diferentes membranas produzidas. Os resultados mostraram que é possível obter membranas celulósicas com total aderência das diferentes camadas, a qual pode ser atribuída às condições de transferência de massa que retardam a precipitação na região próxima à interface das soluções espalhadas simultaneamente. Com relação aos testes de OI e NF, as membranas desenvolvidas apresentaram valores de fluxo permeado (7 - 465 L/h.m²) dentro da faixa das membranas comerciais, retenção salina (NaCl) entre 24-63 % e retenção do PEG entre 53-82 %, mostrando o potencial de aplicação destas membranas.

The purpose of this work is to investigate the preparation of composite anisotropic membranes in a single stage, through the technique of simultaneous casting of two polymer solutions (cellulose acetate (CA)/acetone/formamide (26.3/50/23.7 % w/w) and CA/polyvinylpyrrolidone/dimethyl formamide (15/10/75 % w/w)). The precipitation of the solutions was followed using light transmission experiments. The effect of the exposition period precipitation bath on the membrane properties is also reported. All the membranes were characterized by scanning electron microscopy and by permeation experiments. The RO and NF experiments are carried out using 5,000 mug/g (ppm) of NaCl aqueous solution and 5 g/L of polyethyleneglycol (PEG), 6 KDa, aqueous solution, respectively. Moreover, to reduce defects in the upper layer, the membranes were immersed in a water bath at 90°C for 60 minutes. The membrane morphology analysis indicates that is possible to obtain complete adhesion of the two layers. This result is related to the mass transfer conditions, which should delay the precipitation in the regions near the polymer solutions interface. Regarding the performance of the membranes in RO and NF experiments, the permeate fluxes are comparable to those observed with commercial membranes (7--465 L/h.m²). The solute retention varied in the range of 24 to 63% for NaCl, and in the range of 53 to 82% for PEG. These results point out the potential of technical scale application of the double layer membranes.