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Journal ArticleDOI

Microstructure of the near-wall layer of filtration-induced colloidal assembly.

04 Nov 2020-Soft Matter (The Royal Society of Chemistry)-Vol. 16, Iss: 42, pp 9726-9737

TL;DR: An experimental study of filtration of a colloidal suspension using microfluidic devices involving colloid-colloid repulsive interactions and fluid velocity, which shows some heterogeneity in the near-wall layer microstructure.

AbstractThis paper describes an experimental study of filtration of a colloidal suspension using microfluidic devices. A suspension of micrometer-scale colloids flows through parallel slit-shaped pores at fixed pressure drop. Clogs and cakes are systematically observed at pore entrance, for variable applied pressure drop and ionic strength. Based on image analysis of the layer of colloids close to the device wall, global and local studies are performed to analyse in detail the near-wall layer microstructure. Whereas global porosity of this layer does not seem to be affected by ionic strength and applied pressure drop, a local study shows some heterogeneity: clogs are more porous at the vicinity of the pore than far away. An analysis of medium-range order using radial distribution function shows a slightly more organized state at high ionic strength. This is confirmed by a local analysis using two-dimension continuous wavelet decomposition: the typical size of crystals of colloids is larger for low ionic strength, and it increases with distance from the pores. We bring these results together in a phase diagram involving colloid–colloid repulsive interactions and fluid velocity.

Topics: Pressure drop (57%), Ionic strength (53%), Suspension (chemistry) (53%), Filtration (50%)

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This is an author’s version published in: https://oatao.univ-toulouse.fr/2 74 62
To cite this version:
Mokrane, Mohand Larbi and Desclaux, Térence and Moris, Jeffrey F. and Joseph,
Pierre and Liot, Olivier
Microstructure of the near-wall layer of filtration-induced
colloidal assembly. (2020) Soft Matter, 16 (42). 9726-9737. ISSN 1744-683X .
Official URL:
https://doi.org/10.1039/D0SM01143F
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Journal ArticleDOI
Abstract: Filter cake formation is the predominant phenomenon limiting the filtration performance of membrane separation processes. However, the filter cake’s behavior at the particle scale, which determines its overall cake behavior, has only recently come into the focus of scientists, leaving open questions about its formation and filtration behavior. The present study contributes to the fundamental understanding of soft filter cakes by analyzing the influence of the porous membrane’s morphology on crystal formation and the compaction behavior of soft filter cakes under filtration conditions. Microfluidic chips with nanolithographic imprinted filter templates were used to trigger the formation of crystalline colloidal filter cakes formed by soft microgels. The soft filter cakes were observed via confocal laser scanning microscopy (CLSM) under dead-end filtration conditions. Colloidal crystal formation in the cake, as well as their compaction behavior, were analyzed by optical visualization and pressure data. For the first time, we show that exposing the soft cake to a crystalline filter template promotes the formation of colloidal crystallites and that soft cakes experience gradient compression during filtration.

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Journal ArticleDOI
Abstract: The almost ubiquitous, though undesired, deposition and accumulation of suspended/dissolved matter on solid surfaces, known as fouling, represents a crucial issue strongly affecting the efficiency and sustainability of micro-scale reactors. Fouling becomes even more detrimental for all the applications that require the use of membrane separation units. As a matter of fact, membrane technology is a key route towards process intensification, having the potential to replace conventional separation procedures, with significant energy savings and reduced environmental impact, in a broad range of applications, from water purification to food and pharmaceutical industries. Despite all the research efforts so far, fouling still represents an unsolved problem. The complex interplay of physical and chemical mechanisms governing its evolution is indeed yet to be fully unraveled and the role played by foulants' properties or operating conditions is an area of active research where microfluidics can play a fundamental role. The aim of this review is to explore fouling through microfluidic systems, assessing the fundamental interactions involved and how microfluidics enables the comprehension of the mechanisms characterizing the process. The main mathematical models describing the fouling stages will also be reviewed and their limitations discussed. Finally, the principal dynamic investigation techniques in which microfluidics represents a key tool will be discussed, analyzing their employment to study fouling.

References
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Journal ArticleDOI
TL;DR: Comparisons with other multiresolution texture features using the Brodatz texture database indicate that the Gabor features provide the best pattern retrieval accuracy.
Abstract: Image content based retrieval is emerging as an important research area with application to digital libraries and multimedia databases. The focus of this paper is on the image processing aspects and in particular using texture information for browsing and retrieval of large image data. We propose the use of Gabor wavelet features for texture analysis and provide a comprehensive experimental evaluation. Comparisons with other multiresolution texture features using the Brodatz texture database indicate that the Gabor features provide the best pattern retrieval accuracy. An application to browsing large air photos is illustrated.

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Book
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2,323 citations


Journal ArticleDOI
Daniel Conroy-Beam1, David M. Buss2, Kelly Asao2, Agnieszka Sorokowska3, Agnieszka Sorokowska4, Piotr Sorokowski3, Toivo Aavik5, Grace Akello6, Mohammad Madallh Alhabahba7, Charlotte Alm8, Naumana Amjad9, Afifa Anjum9, Chiemezie S. Atama10, Derya Atamtürk Duyar11, Richard Ayebare, Carlota Batres12, Mons Bendixen13, Aicha Bensafia14, Boris Bizumic15, Mahmoud Boussena14, Marina Butovskaya16, Marina Butovskaya17, Seda Can18, Katarzyna Cantarero19, Antonin Carrier20, Hakan Cetinkaya21, Ilona Croy4, Rosa María Cueto22, Marcin Czub3, Daria Dronova17, Seda Dural18, İzzet Duyar11, Berna Ertuğrul23, Agustín Espinosa22, Ignacio Estevan24, Carla Sofia Esteves25, Luxi Fang26, Tomasz Frackowiak3, Jorge Contreras Garduño27, Karina Ugalde González, Farida Guemaz, Petra Gyuris28, Mária Halamová29, Iskra Herak20, Marina Horvat30, Ivana Hromatko31, Chin Ming Hui26, Jas Laile Suzana Binti Jaafar32, Feng Jiang33, Konstantinos Kafetsios34, Tina Kavčič35, Leif Edward Ottesen Kennair13, Nicolas Kervyn20, Truong Thi Khanh Ha19, Imran Ahmed Khilji36, Nils C. Köbis37, Hoang Moc Lan19, András Láng28, Georgina R. Lennard15, Ernesto León22, Torun Lindholm8, Trinh Thi Linh19, Giulia Lopez38, Nguyen Van Luot19, Alvaro Mailhos24, Zoi Manesi39, Rocio Martinez40, Sarah L. McKerchar15, Norbert Meskó28, Girishwar Misra41, Conal Monaghan15, Emanuel C. Mora42, Alba Moya-Garófano40, Bojan Musil30, Jean Carlos Natividade43, Agnieszka Niemczyk3, George Nizharadze, Elisabeth Oberzaucher44, Anna Oleszkiewicz4, Anna Oleszkiewicz3, Mohd Sofian Omar-Fauzee45, Ike E. Onyishi10, Barış Özener11, Ariela Francesca Pagani38, Vilmante Pakalniskiene46, Miriam Parise38, Farid Pazhoohi47, Annette Pisanski42, Katarzyna Pisanski48, Katarzyna Pisanski3, Edna Lúcia Tinoco Ponciano, Camelia Popa49, Pavol Prokop50, Pavol Prokop51, Muhammad Rizwan, Mario Sainz52, Svjetlana Salkičević31, Ruta Sargautyte46, Ivan Sarmány-Schuller53, Susanne Schmehl44, Shivantika Sharad41, Razi Sultan Siddiqui54, Franco Simonetti55, Stanislava Stoyanova56, Meri Tadinac31, Marco Antonio Correa Varella57, Christin-Melanie Vauclair25, Luis Diego Vega, Dwi Ajeng Widarini, Gyesook Yoo58, Marta Zaťková29, Maja Zupančič59 
University of California, Santa Barbara1, University of Texas at Austin2, University of Wrocław3, Dresden University of Technology4, University of Tartu5, Gulu University6, Middle East University7, Stockholm University8, University of the Punjab9, University of Nigeria, Nsukka10, Istanbul University11, Franklin & Marshall College12, Norwegian University of Science and Technology13, University of Algiers14, Australian National University15, Russian State University for the Humanities16, Russian Academy of Sciences17, İzmir University of Economics18, University of Social Sciences and Humanities19, Université catholique de Louvain20, Ankara University21, Pontifical Catholic University of Peru22, Cumhuriyet University23, University of the Republic24, ISCTE – University Institute of Lisbon25, The Chinese University of Hong Kong26, National Autonomous University of Mexico27, University of Pécs28, University of Constantine the Philosopher29, University of Maribor30, University of Zagreb31, University of Malaya32, Central University of Finance and Economics33, University of Crete34, University of Primorska35, Institute of Molecular and Cell Biology36, University of Amsterdam37, Catholic University of the Sacred Heart38, VU University Amsterdam39, University of Granada40, University of Delhi41, University of Havana42, Pontifical Catholic University of Rio de Janeiro43, University of Vienna44, Universiti Utara Malaysia45, Vilnius University46, University of British Columbia47, University of Sussex48, Romanian Academy49, Comenius University in Bratislava50, Slovak Academy of Sciences51, University of Monterrey52, SAS Institute53, DHA Suffa University54, Pontifical Catholic University of Chile55, South-West University "Neofit Rilski"56, University of São Paulo57, Kyung Hee University58, University of Ljubljana59
TL;DR: This work combines this large cross-cultural sample with agent-based models to compare eight hypothesized models of human mating markets and finds that this cross-culturally universal pattern of mate choice is most consistent with a Euclidean model of mate preference integration.
Abstract: Humans express a wide array of ideal mate preferences. Around the world, people desire romantic partners who are intelligent, healthy, kind, physically attractive, wealthy, and more. In order for these ideal preferences to guide the choice of actual romantic partners, human mating psychology must possess a means to integrate information across these many preference dimensions into summaries of the overall mate value of their potential mates. Here we explore the computational design of this mate preference integration process using a large sample of n = 14,487 people from 45 countries around the world. We combine this large cross-cultural sample with agent-based models to compare eight hypothesized models of human mating markets. Across cultures, people higher in mate value appear to experience greater power of choice on the mating market in that they set higher ideal standards, better fulfill their preferences in choice, and pair with higher mate value partners. Furthermore, we find that this cross-culturally universal pattern of mate choice is most consistent with a Euclidean model of mate preference integration.

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Journal ArticleDOI
TL;DR: The fouling behaviour, fouling factors and fouling control strategies were discussed, and recent developments in membrane materials including low-cost filters, membrane modification and dynamic membranes were reviewed.
Abstract: Membrane bioreactors (MBRs) have been actively employed for municipal and industrial wastewater treatments. So far, membrane fouling and the high cost of membranes are main obstacles for wider application of MBRs. Over the past few years, considerable investigations have been performed to understand MBR fouling in detail and to develop high-flux or low-cost membranes. This review attempted to address the recent and current developments in MBRs on the basis of reported literature in order to provide more detailed information about MBRs. In this paper, the fouling behaviour, fouling factors and fouling control strategies were discussed. Recent developments in membrane materials including low-cost filters, membrane modification and dynamic membranes were also reviewed. Lastly, the future trends in membrane fouling research and membrane material development in the coming years were addressed.

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Abstract: This thesis explores transport phenomena in nanochannels on a chip. Fundamental nanofluidic ionic studies form the basis for novel separation and preconcentration applications for proteomic purposes. The measurements were performed with 50-nm-high 1D nanochannels, which are easily accessible from both sides by two microchannels. Nanometer characteristic apertures were manufactured in the bonded structure of Pyrex-amorphous silicon – Pyrex, in which the thickness of the amorphous silicon layer serves as a spacer to define the height of the nanochannels. The geometry of the nanometer-sized apertures is well defined, which simplifies the modeling of the transport across them. Compared to biological pores, the present nanochannels in Pyrex offer increased stability. Fundamental characteristics of nanometer-sized apertures were obtained by impedance spectroscopy measurements of the nanochannel at different ionic strengths and pH values. A conductance plateau (on a log-log scale) was modeled and measured, establishing due to the dominance of the surface charge density in the nanochannels, which induces an excess of mobile counterions to maintain electroneutrality. The nanochannel conductance can be regulated at low ionic strengths by pH adjustment, and by an external voltage applied on the chip to change the zeta potential. This field-effect allows the regulation of ionic flow which can be exploited for the fabrication of nanofluidic devices. Fluorescence measurements confirm that 50-nm-high nanochannels show an exclusion of co-ions and an enrichment of counterions at low ionic strengths. This permselectivity is related to the increasing thickness of the electrical double layer (EDL) with decreasing salt concentrations, which results in an EDL overlap in an aperture if the height of the nanochannel and the thickness of the EDL are comparable in size. The diffusive transport of charged species and therefore the exclusion-enrichment effect was described with a simple model based on the Poisson-Boltzmann equation. The negatively charged Pyrex surface of the nanometer characteristic apertures can be inversed with chemical surface pretreatments, resulting in an exclusion of cations and an enrichment of anions. When a pressure gradient is applied across the nanochannels, charged molecules are electrostatically rejected at the entrance of the nanometer-sized apertures, which can be used for separation processes. Proteomic applications are presented such as the separation and preconcentration of proteins. The diffusion of Lectin proteins with different isoelectric points and very similar compositions were controlled by regulating the pH value of the buffer. When the proteins are neutral at their pI value, the diffusion coefficient is maximal because the biomolecules does not interact electrostatically with the charged surfaces of the nanochannel. This led to a fast separation of three Lectin proteins across the nanochannel. The pI values measured in this experiment are slightly shifted compared to the values obtained with isoelectric focusing because of reversible adsorption of proteins on the walls which affects the pH value in the nanochannel. An important application in the proteomic field is the preconcentration of biomolecules. By applying an electric field across the nanochannel, anionic and cationic analytes were preconcentrated on the cathodic side of the nanometer-sized aperture whereas on the anodic side depletion of ions was observed. This is due to concentration polarization, a complex of effects related to the formation of ionic concentration gradients in the electrolyte solution adjacent to an ion-selective interface. It was measured that the preconcentration factor increased with the net charge of the molecule, leading to a preconcentration factor of > 600 for rGFP proteins in 9 minutes. Such preconcentrations are important in micro total analysis systems to achieve increased detection signals of analytes contained in dilute solutions. Compared to cylindrical pores, our fabrication process allows the realization of nanochannels on a chip in which the exclusion-enrichment effect and a big flux across the nanometer-sized aperture can be achieved, showing the interest for possible micro total analysis system applications. The described exclusion-enrichment effect as well as concentration polarization play an important role in transport phenomena in nanofluidics. The appendix includes preliminary investigations in DNA molecule separation and fluorescence correlation spectroscopy measurements, which allows investigating the behavior of molecules in the nanochannel itself.

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