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A novel modification technique employing a layer-by-layer (LbL) self-assembly method, integrated with a pressure-assisted filtration system, was developed for enhancing a commercial polyethersulfone (PES) microfiltration (MF) membrane. This modification involved the incorporation of tannic acid (TA) in conjunction with graphene oxide (GO) nanosheets. The effectiveness of the LbL method was confirmed through comprehensive characterization analyses, including ATR-FTIR, SEM, water contact angle (WCA), and mean pore size measurements, comparing the modified membrane with the original commercial one. Sixteen variations of PES MF membranes were superficially modified using a three-factorial design, with the deposited amount of TA and GO as key factors. The influence of these factors on the morphology and performance of the membranes was systematically investigated, focusing on parameters such as pure water permeability (PWP), blue corazol (BC) dye removal efficiency, and flux recovery rate (FRR). The membranes produced with the maximum amount of GO (0.1 mg, 0.55 wt%) and TA as the inner and outer layers demonstrated remarkable FRR and significant BC removal, exceeding 80%. Notably, there was no significant difference observed when using either 0.2 (1.11 wt%) or 0.4 mg (2.22 wt%) in the first layer, as indicated by the Tukey mean test. Furthermore, the modified membrane designated as MF/TA0.4GO0.1TA0.4 was evaluated in the filtration of a simulated dye bath wastewater, exhibiting a BC removal efficiency of 49.20% and a salt removal efficiency of 27.74%. In conclusion, the novel PES MF membrane modification proposed in this study effectively enhances the key properties of pressure-driven separation processes.

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Photocatalytic membranes (PM) have been investigated as an antifouling strategy for membrane separation processes. Coating ceramic membranes with photocatalytic layers can provide a highly active surface capable of degrading foulants and smaller molecules improving the membrane's performance when the surface is irradiated by a suitable light. Nevertheless, the coating process often leads to pore blockage due to the formation or deposition of thick layers of photocatalyst on membrane surfaces, which modifies the original membranes' average pore size and reduces membrane permeability. A facile sol-gel dip coating process was used to produce PM without modifying the original surface morphology of alumina microfiltration membranes. A 3.7-fold increase in permeate volume after 90 minutes of permeation of an acetaminophen solution in continuous filtration mode under UV light (λ = 365 nm LED, 10W) using titania as photocatalyst compared to the bare alumina membrane without irradiation. Furthermore, fouling modeling proved a reduction in the fouling constant, while fouling mechanisms were not modified. Raman analysis showed 100% anatase formed on the membrane surface. Although membranes could remove up to 87% TOC for oily wastewater filtration, antifouling capabilities for this type of effluent were not observed for the photocatalytic membranes mainly due to fouling inside the pores and light attenuation due to the thick fouling layer on the membrane surface.

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The recovery of valuable compounds like phenolic compounds and sugars from grape marc extracts implies different steps, including clarification. In this study, a response surface methodology (RSM) was used as a statistical tool to study the effects of operating conditions such as transmembrane pressure (TMP), temperature and feed flow rate on the performance of a microfiltration (MF) monotubular ceramic membrane with a pore size of 0.14 µm in the clarification of grape marc extract from the Carménère variety, as well to optimize the process conditions by implementing the Box-Behnken statistical design. The desirability function approach was applied to analyze the regression model equations in order to maximize the permeate flux and concentration of malvidin-3-O-glucoside, glucose and fructose in the clarified extract. The optimal operating conditions were found to be 1 bar, 29.01 °C and 5.64 L/min. Under these conditions, the permeate flux and concentration of malvidin-3-O-glucoside, glucose and fructose resulted in 65.78 L/m2h, 43.73 mg/L, 305.89 mg/L, and 274.85 mg/L, respectively.

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Introducción: El grado de microfiltración en el ionómero de vidrio y la resina compuesta nanoparticulada en lesiones cervicales no cariosas es de gran importancia para elegir el material restaurador más adecuado para cada caso clínico. Objetivo: Describir el grado de microfiltración en ionómero de vidrio y resina compuesta nanoparticulada en lesiones cervicales no cariosas. Métodos: Se realizó una revisión bibliográfica, correspondiente al nivel exploratorio, en busca de responder cinco preguntas científicas sobre el tema. Se identificaron 62 artículos de las bases de datos de Google Académico o Scopus entre 2015 y 2022. Resultados: Los estudios consultados sugieren que la resina compuesta nanoparticulada es una opción de restauración efectiva y estética en odontología, especialmente en casos de cavidades de alta carga mecánica y estética dental. Los estudios de casos que se revisan demuestran que el grado de microfiltración en las lesiones cervicales no cariosas puede ser significativamente mayor en las restauraciones con ionómero de vidrio en comparación con las resinas compuestas nanoparticuladas. Conclusiones: Se concluye que el elemento fundamental en el tratamiento es realizar un correcto diagnóstico, determinando las necesidades para mejorar la salud dental y realizar una correcta planificación, por lo que es necesario conocer los diferentes tipos de tratamientos con la finalidad de seleccionar el más adecuado, que cumpla con las características biológicas, mecánicas y estéticas, ya que uno de los objetivos fundamentales de cualquier tratamiento es devolver la función y la estética de modo satisfactorio y con la mayor durabilidad posible.

Introduction: The degree of microleakage in glass ionomer and nanoparticulated composite resin in non-carious cervical lesions is of great importance for choosing the most suitable restorative material for each clinical case. Objective: To describe the degree of microleakage in glass ionomer and nanoparticulated composite resin in non-carious cervical lesions. Methods: A literature review, corresponding to the exploratory level, was carried out to answer five scientific questions on the subject. Sixty-two articles were identified from Academic Google or Scopus databases between 2015 and 2022. Results: The studies consulted suggest that nanoparticulated composite resin is an effective and esthetic restorative option in dentistry, especially in cases of cavities with high mechanical load and dental esthetics. The case studies reviewed demonstrate that the degree of microleakage in non-carious cervical lesions can be significantly higher in glass ionomer restorations compared to nanoparticulated composite resins. Conclusions: It is concluded that the fundamental element in treatment is to carry out a correct diagnosis, determining the needs to improve dental health and to carry out correct planning, so it is necessary to know the different types of treatments with the aim of selecting the most suitable one, which complies with the biological, mechanical and esthetic characteristics, since one of the fundamental objectives of any treatment is to restore function and esthetics in a satisfactory way and with the greatest possible durability.

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This work explores the techno-economic aspects of landfill leachate treatment by an integrated scheme composed of microfiltration (MF), nanofiltration (NF), and zeolite application for carbon and nitrogen removal. In bench-scale experiments, MF and NF were investigated, and zeolite batch tests were carried out to determine optimum conditions. A preliminary economic analysis is presented for a 200 m3 d-1 full-scale treatment facility based on the data obtained from experimental tests and literature surveys. The maximum removals of 92%, 94%, and 79% for chemical oxygen demand (COD), absorbance at 254 nm, and ammonium nitrogen (NH4+-N) were achieved in bench experiments, respectively. It was possible to reach the local discharge standard for COD (200 mg L-1), but it was not possible to reach the Brazilian disposal requirement for NH4+-N (20 mg L-1). The total cost of the integrated MF + NF + zeolite system was estimated at 19.89 US$m-3. In this study, the costs of the zeolite application account for around 70% of the total costs of the integrated scheme. Membrane process integration was an adequate strategy for removing organic compounds at low operating costs; However, further NH4+-N depuration is needed to meet discharge requirements.

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Since it is known that hyaluronic acid contributes to soft tissue growth, elasticity, and scar reduction, different strategies of producing HA have been explored in order to satisfy the current demand of HA in pharmaceutical products and formulations. The current interest deals with production via bacterial and yeast fermentation and extraction from animal sources; however, the main challenge is the right extraction technique and strategy since the original sources (e.g., fermentation broth) represent a complex system containing a number of components and solutes, which complicates the achievement of high extraction rates and purity. This review sheds light on the main pathways for the production of HA, advantages, and disadvantages, along with the current efforts in extracting and purifying this high-added-value molecule from different sources. Particular emphasis has been placed on specific case studies attempting production and successful recovery. For such works, full details are given together with their relevant outcomes.

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With the aim of exploring new materials and properties, we report the synthesis of a thermoplastic chain extended polyurethane membrane, with superior strength and toughness, obtained by incorporating two different concentrations of reactive cellulose nanocrystals (CNC) for potential use in kidney dialysis. Membrane nanocomposites were prepared by the phase inversion method and their structure and properties were determined. These materials were prepared from a polyurethane (PU) yielded from poly(1,4 butylene adipate) as a soft segment diol, isophorone diisocyanate (IPDI) and hexamethylenediamine (HMDA) as isocyanate and chain extender, respectively (hard segment), filled with 1 or 2% w/w CNC. Membrane preparation was made by the phase inversion method using N,N-dimethylformamide as solvent and water as nonsolvent, and subjected to dead-end microfiltration. Membranes were evaluated by their pure water flux, water content, hydraulic resistance and protein rejection. Polymers and nanocomposites were characterized by scanning electronic and optical microscopy, differential scanning calorimetry, infrared spectroscopy, strain stress testing and 13C solid state nuclear magnetic resonance. The most remarkable effects observed by the addition of CNCs are (i) a substantial increment in Young's modulus to twenty-two times compared with the neat PU and (ii) a marked increase in pure water flux up to sixty times, for sample containing 1% (w/w) of CNC. We found that nanofiller has a strong affinity to soft segment diol, which crystallizes in the presence of CNCs, developing both superior mechanical and pure water flow properties, compared to neat PU. The presence of nanofiller also modifies PU intermolecular interactions and consequently the nature of membrane pores.

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OBJECTIVE: to determine the presence of marginal bacterial microfiltration in the IAI in different implant/abutment systems, in vitro. MATERIAL AND METHODS: Fifty-six implants from seven different brand names, 4 with cone and 3 with straight connections were used, implant and abutment were connected using the Ncm tightening as indicated by each of the manufacturers and then were sealed. The samples were subjected occlusal load and thermal cycling, a first sample of each group was observed by micro CT and in a second sample (both samples randomly selected) length of connection was measured, while the rest of the samples were mounted on devices according to the bacterial microfiltration model with Porphyromonas gingivalis. RESULTS: Two of the conical connection system groups did not present bacterial microfiltration, one of the three straight connection groups only microfiltered in one sample, while the other two conical as well as the two straight connection samples showed different and important levels of bacterial microfiltration, all groups presented a direct relationship between the implant-abutment adjustment determined by micro-CT and bacterial microfiltration levels, not related to the connection length. CONCLUSION: Only two conical connection systems presented no bacterial microfiltration.

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In this study, fresh orange prickly pear juice (Opuntia spp.) was clarified by a cross-flow microfiltration (MF) process on a laboratory scale. The viability of the process-in terms of productivity (permeate flux of 77.80 L/h) and the rejection of selected membranes towards specific compounds-was analyzed. The quality of the clarified juice was also analyzed for total antioxidants (TEAC), betalains content (mg/100 g wet base), turbidity (NTU) and colorimetry parameters (L, a*, b*, Croma and H). The MF process permitted an excellent level of clarification, reducing the suspended solids and turbidity of the fresh juice. In the clarified juice, a decrease in total antioxidants (2.03 TEAC) and betalains content (4.54 mg/100 g wet basis) was observed as compared to the fresh juice. Furthermore, there were significant changes in color properties due to the effects of the L, a*, b*, C and h° values after removal of turbidity of the juice. The turbidity also decreased (from 164.33 to 0.37 NTU).

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Poultry processing plants generate large amounts of wastewater in the many steps necessary to provide high quality and safe products. Carcass chilling is one of these steps, where the temperature of the carcass is reduced from 40°C to 4°C, for reducing the growth rate of microorganisms and affecting flavour, texture and appearance. In this operation, carcasses are continually displaced through a series of two tanks (called pre-chiller and chiller) filled with cold water, thus being responsible for a considerable amount of wastewater generation. This work aimed to regenerate the wastewater of the pre-chiller tank employing microfiltration (pore size 0.10 and 0.20 µm) and ultrafiltration (UF; MWCO 10 and 50 kDa) polymeric membranes in bench and pilot scales, with the final purpose of reuse. Membrane performance was evaluated in terms of the capacity of removing the contaminants and producing sufficient permeate flux in different working pressures. Bench-scale UF membrane presented the highest initial permeate flux of 112.1 L/m2h at 200 kPa. The four membranes tested presented good retention of microorganisms, with apparent rejection of up to 100%. Pilot-scale membranes presented better apparent rejection, with retentions above 99% for turbidity, apparent colour and fat content. Moreover, organic matter retention was also very high, up to 94% for chemical oxygen demand and 92% for total organic carbon. The use of membranes seems to be a promising approach for recycling and reuse of poultry pre-chiller wastewater.

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A modified microfiltration (MF) membrane was prepared by flow-through coating method. First the sulfuric acid solution was vacuum filtered on the polyethersulfone (PES) MF membrane, providing the introduction of a sulfonic acid group to the backbone of PES. Sequentially, the polyethyleneimine solution was vacuum filtered to provide amine groups on the membrane surface. Finally, the graphene oxide solution, functionalized with different masses of tannic acid, was vacuum filtered on the membrane surface, producing the cross-linked modified membranes. These were efficient in the removal of anionic food colouring, achieving high removal rates and low fouling, compared to unmodified membrane. The best membrane in terms of bright blue dye removal was the MF PEI5GO1TA4, capable of removing all the feed solution, and demonstrating its possibility of reuse in five cycles of operation.

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Centrifugation techniques are frequently used to separate bacteria from the culture broth in pharmaceutical industries. Alternatively, cell separation can be performed through tangential microfiltration systems; an arguably cost-effective alternative to centrifugation. Therefore, replacement of centrifugation steps with microfiltration represents an attractive option in order to decrease production costs. An example of such use can be found in the production of the vaccine against Haemophilus influenzae type b (Hib), which relies on a centrifugation step to separate the pathogenic bacteria from the antigen-rich (exopolysaccharide) released into culture broth. The substitution of the centrifugation operation with tangential microfiltration may decrease production costs and increase vaccine availability in low-income regions. Hence, we studied the impact of diverse microfiltration systems at different production scales in the separation of Hib from its culture broth. The recovery of the exopolysaccharide - polyribosylribitol phosphate (PRP), the antigen employed in the vaccine, produced by Hib and present in the culture broth was used as a read-out for process efficiency. In sum, the use of Hydrophilic Polyvinylidene Fluoride (PVDF) membranes resulted in the highest recovery value among the tested materials; moreover, the transmembrane pressure was a paramount factor determining the recovery level. We concluded that Hib cell separation through tangential microfiltration systems represents a feasible alternative to centrifugation.

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Limiting flux (JL) determination is a critical issue for membrane processing. This work presents a modified exponential model for JL calculation, based on a previously published version. Our research focused on skim milk microfiltrations. The processing variables studied were the crossflow velocity (CFV), membrane hydraulic diameter (dh), temperature, and concentration factor, totaling 62 experimental runs. Results showed that, by adding a new parameter called minimum transmembrane pressure, the modified model not only improved the fit of the experimental data compared to the former version (R2 > 97.00%), but also revealed the existence of a minimum transmembrane pressure required to obtain flux (J). This result is observed as a small shift to the right on J versus transmembrane pressure curves, and this shift increases with the flow velocity. This fact was reported in other investigations, but so far has gone uninvestigated. The JL predicted values were correlated with the Reynolds number (Re) for each dh tested. Results showed that for a same Re; JL increased as dh decreased; in a wide range of Re within the turbulent regime. Finally, from dimensionless correlations; a unique expression JL = f (Re, dh) was obtained; predicting satisfactorily JL (R2 = 84.11%) for the whole set of experiments.

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Silver nanoparticles were loaded in microfiltration membranes by sputtering technique for the development of biocidal properties and biofouling resistance. This technology allows good adhesion between silver nanoparticles and the membranes, and fast deposition rate. The microfiltration membranes (15 wt.% polyethersulfone and 7.5 wt.% polyvinylpyrrolidone in N,N-dimethylacetamide) were prepared by phase inversion method, and silver nanoparticles were deposited on their surface by the physical technique of vapor deposition in a sputtering chamber. The membranes were characterized by Field Emission Scanning Electron Microscopy, and the presence of silver was investigated by Energy-Dispersive Spectroscopy and X-ray Diffraction. Experiments of silver leaching were carried out through immersion and filtration tests. After 10 months of immersion in water, the membranes still presented ~90% of the initial silver, which confirms the efficiency of the sputtering technique. Moreover, convective experiments indicated that 98.8% of silver remained in the membrane after 24 h of operation. Biocidal analyses (disc diffusion method and biofouling resistance) were performed against Pseudomonas aeruginosa and confirmed the antibacterial activity of these membranes with 0.6 and 0.7 log reduction of viable planktonic and sessile cells, respectively. These results indicate the great potential of these new membranes to reduce biofouling effects.

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RESUMEN Introducción: La microfiltración es uno de los problemas principales de todas las obturaciones a base de resina. Muchos estudios buscan optimizar un buen sellado marginal utilizando diversos acondicionadores, como el hipoclorito de sodio, que permite que el adhesivo penetre bien, al generar desproteinización, y el ácido fosfórico que permite remover el barro dentinario, y así de esta manera formar una capa híbrida al colocar el adhesivo. Objetivo: Evaluar el grado de sellado marginal de la resina Bulk Fill aplicando gel de hipoclorito de sodio 10 por ciento comparado con el gel de ácido fosfórico al 37 por ciento en el acondicionamiento dental in vitro. Métodos: El universo fue de 72 dientes con cavidades clase I; se separaron en 4 grupos por muestra de 18 dientes cada uno; después de obturar se realizó el termociclaje a 500 ciclos entre 5 °C a 55 °C; luego se sumergieron en azul de metileno 2 por ciento, durante 12 h y 24 h a temperatura de 37 °C. Finalmente se evaluó el sellado marginal en el estereomicroscopio, según el ISO / TS 11405: 2015, con los criterios siguientes: grado 0 (sin microfiltración), grado 1 (microfiltración hasta esmalte), grado 2 (microfiltración hasta dentina) y grado 3 (microfiltración hasta piso pulpar). Resultados: El acondicionamiento con ácido fosfórico 37 por ciento a las 12 h presentó grado 0 (55,6 por ciento) y grado 1 (33,3 por ciento), y a las 24 h, grado 1 (55,6 por ciento). Con respecto al hipoclorito de sodio 10 por ciento a las 12 h, grado 0 (44.4 por ciento) y a las 24 h predominó grado 1 (55,6 por ciento). Para la contrastación de hipótesis en muestras relacionadas se obtuvo en ácido fosfórico 37 por ciento e hipoclorito de sodio al 10 por ciento a las 12 h y 24 h un p= 0,052 y p= 0,584, respectivamente. Para comparaciones entre muestras independientes a las 12 h y 24 h se obtuvo p= 0,462 y p= 0,406, respectivamente. Conclusiones: El gel de hipoclorito de sodio al 10 por ciento presenta similar eficacia en el sellado marginal respecto al gel de ácido fosfórico al 37 por ciento, al utilizarlo como acondicionador dental(AU)

ABSTRACT Introduction: Microfiltration is one of the main problems of all resin sealings. Many studies aim to optimize marginal sealing using a variety of conditioners, such as sodium hypochlorite, which allows good penetration of the adhesive by generating deproteinization, and phosphoric acid, which allows removal of the dental smear layer, thus creating a hybrid layer when the adhesive is placed. Objective: Evaluate the marginal sealing degree of Bulk Fill resin applying 10 percent sodium hypochlorite gel versus 37 percent phosphoric acid gel in in vitro dental conditioning. Methods: The study universe was 72 teeth with class I cavities, divided into four groups of 18 teeth. Upon sealing, thermal cycling was performed at 500 cycles from 5 ºC to 55 ºC. Next the teeth were submerged in 2 percent methylene blue for 12 h and 24 h at a temperature of 37 ºC. Finally marginal sealing was evaluated in the stereo microscope according to ISO / TS 11405: 2015, using the following scale: grade 0 (no microfiltration), grade 1 (microfiltration as far as the enamel), grade 2 (microfiltration as far as the dentin), and grade 3 (microfiltration as far as the pulp floor). Results: Conditioning with 37 percent phosphoric acid was grade 0 (55.6 percent) and grade 1 (33.3 percent) at 12 h, and grade 1 (55.6 percent) at 24 h, whereas conditioning with 10 percent sodium hypochlorite was grade 0 (44.4%) at 12 h, and predominantly grade 1 (55.6 percent) at 24 h. Hypothesis contrast in related samples yielded 37 percent phosphoric acid and 10 percent sodium hypochlorite at 12 h and 24 h, p= 0.052 and p= 0.584, respectively. Comparison between independent samples at 12 h and 24 h yielded p= 0.462 and p= 0.406, respectively. Conclusions: The 10 percent sodium hypochlorite gel has similar marginal sealing effectiveness as the 37 percent phosphoric acid gel when used as dental conditioners(AU)

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RESUMO Água do mar é comumente utilizada como fluido de injeção em plataformas offshore na recuperação secundária do petróleo. Porém, a presença de sulfato causa diversos inconvenientes, como a formação de precipitados, que podem se depositar em diversas partes da plataforma de produção. Atualmente, a dessulfatação é realizada em unidades removedoras de sulfato (URS) por processo de nanofiltração (NF), cujas amostras precisam ser pré-tratadas, usualmente em filtros cartuchos. Os sólidos suspensos e os microrganismos que não foram retidos pelo sistema de filtração podem depositar sobre a superfície das membranas de NF, diminuindo a produtividade do sistema e reduzindo o tempo de vida das membranas. O processo de microfiltração (MF) pode ser utilizado como pré-tratamento alternativo e possibilitaria a remoção desses elementos. Neste estudo, foi desenvolvido um processo combinado de MF e NF para a dessulfatação da água do mar, visando a sua injeção em reservatórios de petróleo. Módulos de permeação contendo membranas de poli(imida) no formato de fibras ocas foram utilizados na construção de um sistema piloto de MF integrado a um sistema piloto de NF similar aos já atualmente utilizados nas plataformas. O desempenho dos sistemas foi avaliado por meio do acompanhamento da permeabilidade de ambos durante a filtração da água do mar. Parâmetros como grau de recuperação de água, frequência e eficiência de procedimentos de retrolavagem e limpeza química também foram estudados. Os resultados demonstraram que o pré-tratamento da água do mar por MF é uma alternativa eficaz para a dessulfatação por NF.

ABSTRACT Seawater is commonly used in offshore platforms as an injection fluid in secondary oil recovery. However, the sulfate found in seawater has been the cause of many inconveniences, such as the formation of precipitates, which can settle in various parts of the production platform. Nowadays, nanofiltration (NF) is used in sulfate removal units for seawater desulfation, where cartridge filters are commonly used for seawater pretreatment. Suspended solids and microorganisms that have not been retained by the filtration system may deposit on the surface of NF membranes, decreasing system productivity and reducing membrane life. The microfiltration (MF) process can be used as an alternative pretreatment and would allow the removal of these elements. In this study, a combined process of MF and NF for seawater desulfation was developed for injection into oil reservoirs. Permeation modules containing hollow fiber shaped poly (imide) membranes were used in the construction of an MF pilot system, integrated with an NF pilot system similar to those already used on platforms. The performance of the systems was evaluated by monitoring the permeability of both during seawater filtration. Parameters such as degree of water recovery, frequency, and efficiency of backwash procedures and chemical cleaning were also studied. The results showed that MF seawater pretreatment is an effective alternative for NF desulfation.

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The use of ultrasonic dental scaler (UDS) tips has been investigated for cleaning ceramic membranes fouled when filtering cactus juice. Thin and long tips having a larger coverage exhibited the best performance for removing the cake layer deposited on the membrane surface. Such tips cleaned an area equivalent to almost one third of total area of the membrane surface. However, the cleaned area could be increased notoriously if the membrane were placed in rotatory disc holder. The resistance-in series model and atomic force microscopy (AFM) technique helped to reveal the effect of the UDS tips as cleaning process of ceramic membranes. The reversible resistances estimated for UDS tips were 58% and 17% lower than the ones obtained by chemical cleaning at transmembrane pressures of 0.3 bar and 0.5 bar, respectively. This was corroborated by microscope images, which showed the detachment of cake layer of the membrane surface. Results of this work showed that UDS tips are an innovative option as cleaning strategy for filtration membranes.

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The influence of membrane pore size on the permeate flux, fouling mechanism, and rejection of soluble and suspended solids, as well as of phenolics and anthocyanins, in the clarification of grape marc extract by microfiltration (MF) was studied. MF was operated by using three monotubular ceramic membranes with a pore size of 0.14, 0.2, and 0.8 µm, respectively, according to a batch concentration configuration in selected operating conditions (2.25 bar as operating pressure, 4.93 L/min as feed flow rate, and 25 °C as operating temperature). No significant differences in the permeate flux values were appreciated despite the difference in pore size. The mathematical analyses of the flux behavior revealed that intermediate pore blocking is the predominant mechanism for 0.14 and 0.2 µm membranes, whereas complete pore blocking prevails for the 0.8 µm membrane. Differences in the fouling mechanism were associated with differences in the total phenols rejection: the highest rejection was observed for the 0.8 µm membrane followed by 0.2 and 0.14 µm membranes. All selected membranes showed low rejection of sugars, with values lower than 10%, and no retention towards anthocyanins. All the clarified extracts showed a turbidity lower than 4.87 NTU. Based on the experimental results, the 0.14 µm membrane appeared as the best option for the clarification of grape marc extract.

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RESUMO O objetivo deste trabalho foi discutir os principais parâmetros de controle de um sistema de membranas de microfiltração para remoção de óleo de efluentes com base em ensaios experimentais. Os ensaios utilizaram efluentes sintéticos com diâmetros de gotas de óleo entre 4 e 8 µm. As membranas usadas foram do tipo fibra oca com módulo submerso. Foram testados os seguintes parâmetros: concentrações de óleos e graxas na alimentação das membranas (O&Gam) entre 100 e 260 mg.L-1; taxas de recuperação de água (Rec) de 0,75 e 0,90; e pressões através das membranas (Δp) de -0,20 e -0,30 bar. Os resultados mostraram que as membranas produzem um permeado com uma qualidade boa a ponto de possibilitar o seu reúso em atividades industriais diversas. Foi também observado que a elevação da O&Gam e da Rec acentuam o declínio de fluxo com o tempo e que a elevação da Δp aumenta o valor do fluxo no tempo de seis horas.

ABSTRACT The aim of this paper is to discuss the main control parameters of a microfiltration membranes system for oil removal from effluent on experimental bases. The experiments were conducted by using synthetic effluent with oil droplets diameter ranging from 4 to 8 microns. The membranes used were hollow fiber-type which were assembled in a submerged module. The following parameters were tested: Oil and grease concentration in the feed stream (O&Gf ) of 100 and 200 mg.L-1, Water recovery rates (WRR) of 0.75 and 0.90, and Transmembrane pressure (TMP) of -0.20 and -0.30 bar. The results showed that the membranes produced a permeate with a good quality to the point of enabling their reuse in several industrial activities. It was also observed that the elevation of O&Gf and WRR increase the flux decline over time and that the increase of TMP increases the flow value in time of 6 hours.

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La gutapercha es químicamente un polímero a base de isopreno, impermeable, no poroso y radiopaco entre otras características, empleado desde el siglo XIX; sin embargo manifiesta algunos inconvenientes propios del material, lo cual ha dado lugar al nacimiento de otros materiales para mejorar sus propiedades. Recientemente se ha desarrollado y caracterizado un material novedoso a base de fibra óptica recubierta por nano partículas de plata (FONP), propuesto como un material alternativo para la obturación de conductos radiculares. En el presente estudio se seleccionaron 24 dientes para conformar cuatro grupos experimentales comparativos entre la obturación con fibra óptica y con gutapercha, ambos con el sellador AH Plus. Las raíces fueron obturadas en grupos de diez y almacenadas en solución salina a 37 oC. La filtración apical se midió desde el extremo apical de la interfaz del material hasta la extensión más coronal del tinte observado microscópicamente. Se empleó la herramienta de LAS EZ V3.0 (Leica Microsystems, Switzerland), los datos se tabularon y se analizaron. Resultados: Las mediciones de microfiltración a nivel apical e intraconductos manifestaron diferencias en favor de la gutapercha, donde los grupos experimentales manifestaron una filtración promedio correspondiente a 0.872 mm en el grupo de Gutapercha/AH-PLUS y de 2.390 mm con técnica lateral utilizando FONP/AH-PLUS, aun así se evidenció que las propiedades de sellado de la fibra óptica con nanopartículas fueron suficientes para considerarlo como un material de obturación de conductos radiculares dentales como posible sustituto de la gutapercha (AU)

Gutta-percha is chemically an Isoprene-based polymer, impervious, non-porous and radiopaque, among other characteristics, used since the 19th century, it manifests some disadvantages inherent to the material, which has led to the birth of new materials with improved properties. Recently, a novel material based on optical fiber covered by silver nanoparticles (FONP) has been developed, characterized and proposed as an alternative material for root canal obturation. In the present study, 24 teeth were selected and divided into four comparative experimental groups for obturation with fiber optics and gutta-percha, both with the AH Plus sealer. The roots were sealed in groups of ten and stored in saline at 37 oC. Apical filtration test was performed from the apical end of the material interface to the most coronal extension of the dye observed microscopically. The LAS EZ V3.0 tool was used to make the measurements and the data was tabulated and analyzed. Results: Measurements of microfiltration at the apical and intracanal level showed differences in favor of gutta-percha, where the experimental groups showed an average filtration of 0.872 mm in the Gutapercha/AH-PLUS group and 2.390 mm using FONP/AH-PLUS, even so, it was evidenced that the sealing properties of the optical fiber with nanoparticles are sufficient to consider this material as a proper filling material for dental root canals as a substitute for gutta-percha (AU)

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