1
|
Abdel-Aty AA, Ahmed RM, ElSherbiny IM, Panglisch S, Ulbricht M, Khalil AS. Superior Separation of Industrial Oil-in-Water Emulsions Utilizing Surface Patterned Isotropic PES Membranes. Sep Purif Technol 2023. [DOI: 10.1016/j.seppur.2023.123286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
|
2
|
Shao S, Zeng F, Long L, Zhu X, Peng LE, Wang F, Yang Z, Tang CY. Nanofiltration Membranes with Crumpled Polyamide Films: A Critical Review on Mechanisms, Performances, and Environmental Applications. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:12811-12827. [PMID: 36048162 DOI: 10.1021/acs.est.2c04736] [Citation(s) in RCA: 27] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Nanofiltration (NF) membranes have been widely applied in many important environmental applications, including water softening, surface/groundwater purification, wastewater treatment, and water reuse. In recent years, a new class of piperazine (PIP)-based NF membranes featuring a crumpled polyamide layer has received considerable attention because of their great potential for achieving dramatic improvements in membrane separation performance. Since the report of novel crumpled Turing structures that exhibited an order of magnitude enhancement in water permeance ( Science 2018, 360 (6388), 518-521), the number of published research papers on this emerging topic has grown exponentially to approximately 200. In this critical review, we provide a systematic framework to classify the crumpled NF morphologies. The fundamental mechanisms and fabrication methods involved in the formation of these crumpled morphologies are summarized. We then discuss the transport of water and solutes in crumpled NF membranes and how these transport phenomena could simultaneously improve membrane water permeance, selectivity, and antifouling performance. The environmental applications of these emerging NF membranes are highlighted, and future research opportunities/needs are identified. The fundamental insights in this review provide critical guidance on the further development of high-performance NF membranes tailored for a wide range of environmental applications.
Collapse
Affiliation(s)
- Senlin Shao
- School of Civil Engineering, Wuhan University, Wuhan 430072, PR China
| | - Fanxi Zeng
- School of Civil Engineering, Wuhan University, Wuhan 430072, PR China
| | - Li Long
- Department of Civil Engineering, The University of Hong Kong, Pokfulam, Hong Kong, SAR, China
| | - Xuewu Zhu
- School of Municipal and Environmental Engineering, Shandong Jianzhu University, Jinan 250101, PR China
| | - Lu Elfa Peng
- Department of Civil Engineering, The University of Hong Kong, Pokfulam, Hong Kong, SAR, China
| | - Fei Wang
- Department of Civil Engineering, The University of Hong Kong, Pokfulam, Hong Kong, SAR, China
| | - Zhe Yang
- Department of Civil Engineering, The University of Hong Kong, Pokfulam, Hong Kong, SAR, China
| | - Chuyang Y Tang
- Department of Civil Engineering, The University of Hong Kong, Pokfulam, Hong Kong, SAR, China
| |
Collapse
|
3
|
Azine-linked covalent organic framework-modified GO membrane for high-efficiency separation of aqueous dyes and salts in wastewater. J Memb Sci 2022. [DOI: 10.1016/j.memsci.2022.120546] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
|
4
|
Bachosz K, Piasecki A, Zdarta A, Kaczorek E, Pinelo M, Zdarta J, Jesionowski T. Enzymatic membrane reactor in xylose bioconversion with simultaneous cofactor regeneration. Bioorg Chem 2022; 123:105781. [PMID: 35395447 DOI: 10.1016/j.bioorg.2022.105781] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Revised: 03/29/2022] [Accepted: 03/30/2022] [Indexed: 12/22/2022]
Abstract
In this study, we present the concept of co-immobilization of xylose dehydrogenase and alcohol dehydrogenase from Saccharomyces cerevisiae on an XN45 nanofiltration membrane for application in the process of xylose bioconversion to xylonic acid with simultaneous cofactor regeneration and membrane separation of reaction products. During the research, the effectiveness of the co-immobilization of enzymes was confirmed, and changes in the properties of the membrane after the processes were determined. Using the obtained biocatalytic system it was possible to obtain 99% xylonic acid production efficiency under optimal conditions, which were 5 mM xylose, 5 mM formaldehyde, ratio of NAD+:NADH 1:1, and 60 min of reaction. Additionally, the co-immobilization of enzymes made it possible to improve stability of the co-immobilized enzymes and to carry out xylose conversion in six consecutive cycles and after 7 days of storage at 4 °C with over 90% efficiency. The presented data confirm the effectiveness of the co-immobilization, improvement of the stability and reusability of the biocatalysts, and show that the obtained enzymatic system is promising for use in xylose bioconversion and simultaneous regeneration of nicotinamide cofactor.
Collapse
Affiliation(s)
- Karolina Bachosz
- Institute of Chemical Technology and Engineering, Faculty of Chemical Technology, Poznan University of Technology, Berdychowo 4, PL-60965 Poznan, Poland.
| | - Adam Piasecki
- Institute of Materials Science and Engineering, Faculty of Mechanical Engineering and Management, Poznan University of Technology, Jana Pawla II 24, PL-60965 Poznan, Poland.
| | - Agata Zdarta
- Institute of Chemical Technology and Engineering, Faculty of Chemical Technology, Poznan University of Technology, Berdychowo 4, PL-60965 Poznan, Poland.
| | - Ewa Kaczorek
- Institute of Chemical Technology and Engineering, Faculty of Chemical Technology, Poznan University of Technology, Berdychowo 4, PL-60965 Poznan, Poland.
| | - Manuel Pinelo
- Department of Chemical and Biochemical Engineering, Technical University of Denmark, Soltofts Plads, Building 227, DK-2800 Kongens Lyngby, Denmark.
| | - Jakub Zdarta
- Institute of Chemical Technology and Engineering, Faculty of Chemical Technology, Poznan University of Technology, Berdychowo 4, PL-60965 Poznan, Poland.
| | - Teofil Jesionowski
- Institute of Chemical Technology and Engineering, Faculty of Chemical Technology, Poznan University of Technology, Berdychowo 4, PL-60965 Poznan, Poland.
| |
Collapse
|
5
|
Spheres-in-Grating Assemblies with Altered Photoluminescence and Wetting Properties. NANOMATERIALS 2022; 12:nano12071084. [PMID: 35407201 PMCID: PMC9000395 DOI: 10.3390/nano12071084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/27/2022] [Revised: 03/21/2022] [Accepted: 03/23/2022] [Indexed: 11/17/2022]
Abstract
In this work, we report the fabrication of spheres-in-grating assemblies consisting of equally spaced parallel rectangular grooves filled with fluorescent spheres, by employing embossing and convective self-assembly methods. The developed hierarchical assemblies, when compared to spheres spin-cast on glass, exhibited a blueshift in the photoluminescence spectra, as well as changes in wetting properties induced not only by the patterning process, but also by the nature and size of the utilized spheres. While the patterning process led to increased hydrophobicity, the utilization of spheres with larger diameter improved the hydrophilicity of the fabricated assemblies. Finally, by aiming at the future integration of the spheres-in-grating assemblies as critical components in different technological and medical applications, we report a successful encapsulation of the incorporated spheres within the grating with a top layer of a functional polymer.
Collapse
|
6
|
Qiao Y, Shang Z, Kou R. Molecular-sized outward-swinging gate: Experiment and theoretical analysis of a locally nonchaotic barrier. Phys Rev E 2022; 104:064133. [PMID: 35030897 DOI: 10.1103/physreve.104.064133] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Accepted: 12/03/2021] [Indexed: 11/07/2022]
Abstract
We investigate the concept of molecular-sized outward-swinging gate, which allows for entropy decrease in an isolated system. The theoretical analysis, the Monte Carlo simulation, and the direct solution of governing equations all suggest that under the condition of local nonchaoticity, the probability of particle crossing is asymmetric. It is demonstrated by an experiment on a nanoporous membrane one-sidedly surface-grafted with bendable organic chains. Remarkably, through the membrane, gas spontaneously and repeatedly flows from the low-pressure side to the high-pressure side. While this phenomenon seems counterintuitive, it is compatible with the principle of maximum entropy. The locally nonchaotic gate interrupts the probability distribution of the local microstates, and imposes additional constraints on the global microstates, so that entropy reaches a nonequilibrium maximum. Such a mechanism is fundamentally different from Maxwell's demon and Feynman's ratchet, and is consistent with microscopic reversibility. It implies that useful work may be produced in a cycle from a single thermal reservoir. A generalized form of the second law of thermodynamics is proposed.
Collapse
Affiliation(s)
- Yu Qiao
- Program of Materials Science and Engineering, University of California - San Diego, La Jolla, California 92093, USA.,Department of Structural Engineering, University of California - San Diego, La Jolla, California 92093-0085, USA
| | - Zhaoru Shang
- Program of Materials Science and Engineering, University of California - San Diego, La Jolla, California 92093, USA
| | - Rui Kou
- Department of Structural Engineering, University of California - San Diego, La Jolla, California 92093-0085, USA
| |
Collapse
|
7
|
Ward LM, Fickling BG, Weinman ST. Effect of Nanopatterning on Concentration Polarization during Nanofiltration. MEMBRANES 2021; 11:961. [PMID: 34940462 PMCID: PMC8707940 DOI: 10.3390/membranes11120961] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Revised: 11/30/2021] [Accepted: 12/02/2021] [Indexed: 11/16/2022]
Abstract
Membranes used for desalination still face challenges during operation. One of these challenges is the buildup of salt ions at the membrane surface. This is known as concentration polarization, and it has a negative effect on membrane water permeance and salt rejection. In an attempt to decrease concentration polarization, a line-and-groove nanopattern was applied to a nanofiltration (NF) membrane. Aqueous sodium sulfate (Na2SO4) solutions were used to test the rejection and permeance of both pristine and patterned membranes. It was found that the nanopatterns did not reduce but increased the concentration polarization at the membrane surface. Based on these studies, different pattern shapes and sizes should be investigated to gain a fundamental understanding of the influence of pattern size and shape on concentration polarization.
Collapse
Affiliation(s)
| | | | - Steven T. Weinman
- Department of Chemical and Biological Engineering, The University of Alabama, Tuscaloosa, AL 35487, USA; (L.M.W.); (B.G.F.)
| |
Collapse
|
8
|
Falca G, Musteata VE, Chisca S, Hedhili MN, Ong C, Nunes SP. Naturally Extracted Hydrophobic Solvent and Self-Assembly in Interfacial Polymerization. ACS APPLIED MATERIALS & INTERFACES 2021; 13:44824-44832. [PMID: 34510885 DOI: 10.1021/acsami.1c07584] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Pharmaceutical, chemical, and food industries are actively implementing membrane nanofiltration modules in their processes to separate valuable products and recover solvents. Interfacial polymerization (IP) is the most widely used method to produce thin-film composite membranes for nanofiltration and reverse osmosis processes. Although membrane processes are considered green and environmentally friendly, membrane fabrication has still to be further developed in such direction. For instance, the emission of volatile solvents during membrane production in the industry has to be carefully controlled for health reasons. Greener solvents are being proposed for phase-separation membrane manufacture. For the IP organic phase, the proposition of greener alternatives is in an early stage. In this work, we demonstrate the preparation of a high-performing composite membrane employing zero vapor pressure and naturally extracted oleic acid as the IP organic phase. Its long hydrophobic chain ensures intrinsic low volatility and acid monomer dissolution, while the polar head induces a unique self-assembly structure during the film formation. Membranes prepared by this technique were selective for small molecules with a molecular weight cutoff of 650 g mol-1 and a high permeance of ∼57 L m-2 h-1 bar-1.
Collapse
Affiliation(s)
- Gheorghe Falca
- Biological and Environmental Science Engineering Division (BESE), Advanced Membranes and Porous Materials Center, King Abdullah University of Science and Technology, 23955-6900 Thuwal, Saudi Arabia
| | - Valentina E Musteata
- Biological and Environmental Science Engineering Division (BESE), Advanced Membranes and Porous Materials Center, King Abdullah University of Science and Technology, 23955-6900 Thuwal, Saudi Arabia
| | - Stefan Chisca
- Biological and Environmental Science Engineering Division (BESE), Advanced Membranes and Porous Materials Center, King Abdullah University of Science and Technology, 23955-6900 Thuwal, Saudi Arabia
| | - Mohamed Nejib Hedhili
- Imaging and Characterization Laboratory, King Abdullah University of Science and Technology, 23955-6900 Thuwal, Saudi Arabia
| | - Chisiang Ong
- Biological and Environmental Science Engineering Division (BESE), Advanced Membranes and Porous Materials Center, King Abdullah University of Science and Technology, 23955-6900 Thuwal, Saudi Arabia
| | - Suzana P Nunes
- Biological and Environmental Science Engineering Division (BESE), Advanced Membranes and Porous Materials Center, King Abdullah University of Science and Technology, 23955-6900 Thuwal, Saudi Arabia
| |
Collapse
|
9
|
Dobosz KM, Kuo-Leblanc CA, Bowden JW, Schiffman JD. Robust, small diameter hydrophilic nanofibers improve the flux of ultrafiltration membranes. Ind Eng Chem Res 2021; 60:9179-9188. [PMID: 34602741 DOI: 10.1021/acs.iecr.1c01332] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In this study, we systematically investigated the flux performance of ultrafiltration (UF) membranes functionalized with randomly-accumulated nanofibers. By electrospinning nanofibers from hydrophobic polysulfone (PSf) and hydrophilic cellulose (CL), we were able to explore the role that bulk nanofiber (NF) layer thickness, individual NF diameter, and intrinsic chemistry have on composite membrane flux. Additional parameters that we systematically tested include the molecular weight cut-off (MWCO) of the base membrane (10, 100, and 200 kDa), flow orientation (cross-flow versus dead-end), and the feed solution (hydrophilic water versus hydrophobic oil). Structurally, the crosslinked PSf nanofibers were more robust than the CL nanofibers, which lead to the PSfNF-UF membranes having a greater flux performance. To decouple the structural robustness from the water affinity of the fibers, we chemically modified the PSf fibers to be hydrophilic and indeed, the flux of these new composite membranes featuring hydrophilic crosslinked nanofibers were superior. In summary, the greatest increase in flux performance arises from the smallest diameter, hydrophilic nanofibers that are mechanically robust (crosslinked). We have demonstrated that electrospun nanofiber layers improve the flux performance of ultrafiltration membranes.
Collapse
Affiliation(s)
- Kerianne M Dobosz
- Department of Chemical Engineering University of Massachusetts Amherst, Amherst, Massachusetts 01003-9303, United States
| | - Christopher A Kuo-Leblanc
- Department of Chemical Engineering University of Massachusetts Amherst, Amherst, Massachusetts 01003-9303, United States
| | - Jared W Bowden
- Department of Chemical Engineering University of Massachusetts Amherst, Amherst, Massachusetts 01003-9303, United States
| | - Jessica D Schiffman
- Department of Chemical Engineering University of Massachusetts Amherst, Amherst, Massachusetts 01003-9303, United States
| |
Collapse
|
10
|
Polyethylene-supported nanofiltration membrane with in situ formed surface patterns of millimeter size in resisting fouling. J Memb Sci 2021. [DOI: 10.1016/j.memsci.2020.118830] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
|
11
|
Handrea-Dragan M, Botiz I. Multifunctional Structured Platforms: From Patterning of Polymer-Based Films to Their Subsequent Filling with Various Nanomaterials. Polymers (Basel) 2021; 13:445. [PMID: 33573248 PMCID: PMC7866561 DOI: 10.3390/polym13030445] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2021] [Revised: 01/25/2021] [Accepted: 01/26/2021] [Indexed: 12/20/2022] Open
Abstract
There is an astonishing number of optoelectronic, photonic, biological, sensing, or storage media devices, just to name a few, that rely on a variety of extraordinary periodic surface relief miniaturized patterns fabricated on polymer-covered rigid or flexible substrates. Even more extraordinary is that these surface relief patterns can be further filled, in a more or less ordered fashion, with various functional nanomaterials and thus can lead to the realization of more complex structured architectures. These architectures can serve as multifunctional platforms for the design and the development of a multitude of novel, better performing nanotechnological applications. In this work, we aim to provide an extensive overview on how multifunctional structured platforms can be fabricated by outlining not only the main polymer patterning methodologies but also by emphasizing various deposition methods that can guide different structures of functional nanomaterials into periodic surface relief patterns. Our aim is to provide the readers with a toolbox of the most suitable patterning and deposition methodologies that could be easily identified and further combined when the fabrication of novel structured platforms exhibiting interesting properties is targeted.
Collapse
Affiliation(s)
- Madalina Handrea-Dragan
- Interdisciplinary Research Institute in Bio-Nano-Sciences, Babes-Bolyai University, 42 Treboniu Laurian Str. 400271 Cluj-Napoca, Romania;
- Faculty of Physics, Babes-Bolyai University, 1 M. Kogalniceanu Str. 400084 Cluj-Napoca, Romania
| | - Ioan Botiz
- Interdisciplinary Research Institute in Bio-Nano-Sciences, Babes-Bolyai University, 42 Treboniu Laurian Str. 400271 Cluj-Napoca, Romania;
| |
Collapse
|
12
|
Malakian A, Zhou Z, Messick L, Spitzer TN, Ladner DA, Husson SM. Understanding the Role of Pattern Geometry on Nanofiltration Threshold Flux. MEMBRANES 2020; 10:445. [PMID: 33371519 PMCID: PMC7767534 DOI: 10.3390/membranes10120445] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 12/17/2020] [Accepted: 12/18/2020] [Indexed: 11/16/2022]
Abstract
Colloidal fouling can be mitigated by membrane surface patterning. This contribution identifies the effect of different pattern geometries on fouling behavior. Nanoscale line-and-groove patterns with different feature sizes were applied by thermal embossing on commercial nanofiltration membranes. Threshold flux values of as-received, pressed, and patterned membranes were determined using constant flux, cross-flow filtration experiments. A previously derived combined intermediate pore blocking and cake filtration model was applied to the experimental data to determine threshold flux values. The threshold fluxes of all patterned membranes were higher than the as-received and pressed membranes. The pattern fraction ratio (PFR), defined as the quotient of line width and groove width, was used to analyze the relationship between threshold flux and pattern geometry quantitatively. Experimental work combined with computational fluid dynamics simulations showed that increasing the PFR leads to higher threshold flux. As the PFR increases, the percentage of vortex-forming area within the pattern grooves increases, and vortex-induced shielding increases. This study suggests that the PFR should be higher than 1 to produce patterned membranes with maximal threshold flux values. Knowledge generated in this study can be applied to other feature types to design patterned membranes for improved control over colloidal fouling.
Collapse
Affiliation(s)
- Anna Malakian
- Department of Chemical and Biomolecular Engineering, Clemson University, Clemson, SC 29634, USA; (A.M.); (L.M.); (T.N.S.)
| | - Zuo Zhou
- Department of Environmental Engineering and Earth Sciences, Clemson University, Clemson, SC 29634, USA; (Z.Z.); (D.A.L.)
| | - Lucas Messick
- Department of Chemical and Biomolecular Engineering, Clemson University, Clemson, SC 29634, USA; (A.M.); (L.M.); (T.N.S.)
| | - Tara N. Spitzer
- Department of Chemical and Biomolecular Engineering, Clemson University, Clemson, SC 29634, USA; (A.M.); (L.M.); (T.N.S.)
| | - David A. Ladner
- Department of Environmental Engineering and Earth Sciences, Clemson University, Clemson, SC 29634, USA; (Z.Z.); (D.A.L.)
| | - Scott M. Husson
- Department of Chemical and Biomolecular Engineering, Clemson University, Clemson, SC 29634, USA; (A.M.); (L.M.); (T.N.S.)
| |
Collapse
|
13
|
Patterning flat-sheet Poly(vinylidene fluoride) membrane using templated thermally induced phase separation. J Memb Sci 2020. [DOI: 10.1016/j.memsci.2020.118627] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
|
14
|
Synthesis of patterned PVDF ultrafiltration membranes: Spray-modified non-solvent induced phase separation. J Memb Sci 2020. [DOI: 10.1016/j.memsci.2020.118383] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
|
15
|
Effect of Short-Term Contact with C1-C4 Monohydric Alcohols on the Water Permeance of MPD-TMC Thin-Film Composite Reverse Osmosis Membranes. MEMBRANES 2019; 9:membranes9080092. [PMID: 31357425 PMCID: PMC6723597 DOI: 10.3390/membranes9080092] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Revised: 07/15/2019] [Accepted: 07/24/2019] [Indexed: 11/22/2022]
Abstract
In this paper, we discuss the effect of alcohol contact on the transport properties of thin-film composite reverse osmosis membranes. Five commercial membranes were studied to quantify the changes in water permeance and sodium chloride rejection from contact with five C1–C4 monohydric, alcohols. Water permeance generally increased without decreasing rejection after short-term contact. The extent of these changes depends on the membrane and alcohol used. Young′s modulus measurements showed decreased stiffness of the active layer after contacting the membranes with alcohol, suggesting plasticization. Data analysis using a dual-mode sorption model identified positive correlations of the initial water permeance, as well as the change in free energy of mixing between water and the alcohols, with the increase in water permeance after alcohol contact. We suggest that the mixing of water with the alcohols facilitates alcohol penetration into the active layer, likely by disrupting inter-chain hydrogen bonds, thus increasing the free volume for water permeation. Our studies provide a modeling framework to estimate the changes in transport properties after short-term contact with C1–C4 alcohols.
Collapse
|