The Experts below are selected from a list of 26436 Experts worldwide ranked by ideXlab platform
Bekir Satilmis - One of the best experts on this subject based on the ideXlab platform.
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Electrospinning of Ultrafine Poly(1-trimethylsilyl-1-propyne) [PTMSP] Fibers: Highly Porous Fibrous Membranes for Volatile Organic Compound Removal
2019Co-Authors: Bekir Satilmis, Tamer UyarAbstract:Poly(1-trimethylsilyl-1-propyne) [PTMSP] possesses a rigid backbone chain with bulky trimethylsilyl side groups which limit the rotational freedom and provide packing-inefficiency that leads extremely high free volume. PTMSP is a hydrophobic polymer showing solubility in common organic solvents such as chloroform and tetrahydrofuran. Therefore, it can be formed as self-standing Dense Membrane (film). Hence, PTMSP is widely studied for separation applications owing to these outstanding properties. The aim of this research is to produce self-standing poly(1-trimethylsilyl-1-propyne) [PTMSP] fibrous Membrane via electrospinning method to further enhance the application area of PTMSP. Electrospinning was achieved using tetrahydrofuran/tetrachloroethane (1:2 v/v) solvent mixture. Extensive optimization studies were performed to obtain bead-free and uniform ultrafine fibers which were obtained at 3.5% (w/v) polymer concentration with respect to solvent, and beads-on-string morphology was obtained below this concentration as confirmed by SEM imaging. Random and aligned fibers were produced using a stationary and a rotating collector, respectively. The optimized sample (P6), which was produced using 12 kV voltage and 20 cm tip-to-collector distance, possesses an average fiber diameter of 1.4 ± 0.4 μm. Additionally, PTMSP Dense Membrane was fabricated by solvent evaporation method to compare the properties with fibrous Membrane. Structural characterization and elemental composition of PTMSP samples were conducted using FT-IR and 1H NMR and XPS spectroscopies. Hydrophobicity of the samples was compared using their water contact angle measurements. While PTMSP Dense Membrane shows 90 ± 2°, the electrospun PTMSP fibrous Membranes possess hydrophobic nature having 145 ± 5° and 152 ± 2° water contact angles for fibers having aligned and random morphology, respectively. In addition, fibrous Membrane possesses high surface area that is the same as powder form showing ∼850 m2/g BET surface area which is slightly higher than that of Dense Membrane (780 m2/g). Consequently, the high surface area electrospun PTMSP fibrous Membrane was tested for volatile organic compounds (VOCs) removal as it can accommodate a significant amount of organic molecules in its porous structure. Furthermore, the VOC entrapment capacity of Dense and fibrous Membrane was compared using aniline, benzene, and toluene as model compounds. PTMSP Membranes have shown the highest uptake for aniline where the uniform fiber morphology was maintained after sorption for fibrous Membrane. In addition, lower boiling point VOCs, benzene and toluene, were trapped in fibrous Membrane higher that the Dense Membrane since they cause swelling in fiber morphology
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amine modified electrospun pim 1 ultrafine fibers for an efficient removal of methyl orange from an aqueous system
Applied Surface Science, 2018Co-Authors: Bekir Satilmis, Tamer UyarAbstract:Abstract Polymers of Intrinsic Microporosity (PIM-1) is a promising material for adsorption and separation applications. While PIM-1 displays high affinity for neutral species, it shows lack of interaction with charged molecules in an aqueous system due to non-polar nature of it. Functionalization of PIM-1 provides an advantage of tailoring the interaction ability as well as the adsorption performance of PIM-1 towards target pollutants. In this study, electrospun Polymer of Intrinsic Microporosity (PIM-1) fibrous Membrane (PIM-FM) was reacted with borane dimethyl sulfide complex to obtain amine modified PIM-1 fibrous Membrane (AM-PIM-FM). Furthermore, PIM-1 film, which is referred as PIM-1 Dense Membrane (PIM-DM), was also modified under the same conditions as a control material. Structural analyses have confirmed that nitrile groups of PIM-1 have been fully converted to amine group as a result of the reduction reaction. Average fiber diameter of parent PIM-1 fibers was found 2.3 ± 0.3 μm, and it remained almost the same after the amine modification. In addition, no physical damage has been observed on fiber structure based on the SEM analysis. Both amine modified PIM-1 Dense and fibrous Membranes became insoluble in common organic solvents. Before the modification, water contact angle of PIM-FM was 138 ± 2° which also remained almost the same after the modification, showing water contact angle of 131 ± 8°. The insolubility along with amine functionality make Membranes promising materials for adsorption of anionic dyes from wastewater. Here, dye (i.e. Methyl Orange) removal ability of AM-PIM-FM from an aqueous system was investigated and compared with parent PIM-1 (PIM-FM) as well as Dense Membrane form (AM-PIM-DM). AM-PIM-FM shows extremely higher adsorption capacity than that of PIM-FM and AM-PIM-DM. The maximum adsorption capacity of AM-PIM-FM was found 312.5 mg g−1 for Methyl Orange. Langmuir isotherm model was found more favorable for the adsorption. AM-PIM-FM was employed effectively in continuous adsorption/desorption studies for several times without having any damage on fiber morphology using batch adsorption process. Furthermore, AM-PIM-FM was successfully used as a molecular filter for the removal of methyl orange from an aqueous system. The results indicate that AM-PIM-FM could be a promising adsorbent for removal of anionic molecules from an aqueous system.
Weishen Yang - One of the best experts on this subject based on the ideXlab platform.
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investigation on the partial oxidation of methane to syngas in a tubular ba0 5sr0 5co0 8fe0 2o3 δ Membrane reactor
Catalysis Today, 2003Co-Authors: Haihui Wang, You Cong, Weishen YangAbstract:Abstract A perovskite material of Ba0.5Sr0.5Co0.8Fe0.2O3−δ (BSCF), with both electronic and ionic conductivity, was synthesized by a combined citrate–EDTA complexing method. The Dense Membrane tube made of BSCF was fabricated using the plastic extrusion method. The partial oxidation of methane (POM) to syngas was performed in the tubular BSCF Membrane reactor packed with a LiLaNiO/γ–Al2O3 catalyst. The reaction performance of the Membrane reactor was investigated as functions of temperature, air flow rate in the shell side and methane concentration in the tube side. The mechanism of POM in the Membrane reactor was discussed in detail. It was found that in the tubular Membrane reactor, combustion reaction of methane with permeated oxygen took place in the reaction zone close to the surface of the Membrane, then followed by steam and CO2 reforming of methane in the middle zone of the tube side. The Membrane tube can be operated steadily for 500 h in pure methane with 94% methane conversion and higher than 95% CO selectivity, and higher than 8.0 ml/cm2 min oxygen permeation flux.
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novel and ideal zirconium based Dense Membrane reactors for partial oxidation of methane to syngas
Catalysis Letters, 2002Co-Authors: Jianhua Tong, Weishen Yang, Rui Cai, Baichun Zhu, Liwu LinAbstract:A novel and ideal Dense catalytic Membrane reactor for the reaction of partial oxidation of methane to syngas (POM) was constructed from the stable mixed conducting perovskite material of BaCo0.4Fe0.4Zr0.2O3−δ and the catalyst of LiLaNiO/γ-Al2O3. The POM reaction was performed successfully. Not only was a short induction period of 2 h obtained, but also a high catalytic performance of 96–98% CH4 conversion, 98–99% CO selectivity and an oxygen permeation flux of 5.4–5.8 ml cm−2 min−1 (1.9–2.0 μmol m−2 S−1 Pa−1) at 850 °C were achieved. Moreover, the reaction has been steadily carried out for more than 2200 h, and no interaction between the Membrane material and the catalyst took place.
Tamer Uyar - One of the best experts on this subject based on the ideXlab platform.
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Electrospinning of Ultrafine Poly(1-trimethylsilyl-1-propyne) [PTMSP] Fibers: Highly Porous Fibrous Membranes for Volatile Organic Compound Removal
2019Co-Authors: Bekir Satilmis, Tamer UyarAbstract:Poly(1-trimethylsilyl-1-propyne) [PTMSP] possesses a rigid backbone chain with bulky trimethylsilyl side groups which limit the rotational freedom and provide packing-inefficiency that leads extremely high free volume. PTMSP is a hydrophobic polymer showing solubility in common organic solvents such as chloroform and tetrahydrofuran. Therefore, it can be formed as self-standing Dense Membrane (film). Hence, PTMSP is widely studied for separation applications owing to these outstanding properties. The aim of this research is to produce self-standing poly(1-trimethylsilyl-1-propyne) [PTMSP] fibrous Membrane via electrospinning method to further enhance the application area of PTMSP. Electrospinning was achieved using tetrahydrofuran/tetrachloroethane (1:2 v/v) solvent mixture. Extensive optimization studies were performed to obtain bead-free and uniform ultrafine fibers which were obtained at 3.5% (w/v) polymer concentration with respect to solvent, and beads-on-string morphology was obtained below this concentration as confirmed by SEM imaging. Random and aligned fibers were produced using a stationary and a rotating collector, respectively. The optimized sample (P6), which was produced using 12 kV voltage and 20 cm tip-to-collector distance, possesses an average fiber diameter of 1.4 ± 0.4 μm. Additionally, PTMSP Dense Membrane was fabricated by solvent evaporation method to compare the properties with fibrous Membrane. Structural characterization and elemental composition of PTMSP samples were conducted using FT-IR and 1H NMR and XPS spectroscopies. Hydrophobicity of the samples was compared using their water contact angle measurements. While PTMSP Dense Membrane shows 90 ± 2°, the electrospun PTMSP fibrous Membranes possess hydrophobic nature having 145 ± 5° and 152 ± 2° water contact angles for fibers having aligned and random morphology, respectively. In addition, fibrous Membrane possesses high surface area that is the same as powder form showing ∼850 m2/g BET surface area which is slightly higher than that of Dense Membrane (780 m2/g). Consequently, the high surface area electrospun PTMSP fibrous Membrane was tested for volatile organic compounds (VOCs) removal as it can accommodate a significant amount of organic molecules in its porous structure. Furthermore, the VOC entrapment capacity of Dense and fibrous Membrane was compared using aniline, benzene, and toluene as model compounds. PTMSP Membranes have shown the highest uptake for aniline where the uniform fiber morphology was maintained after sorption for fibrous Membrane. In addition, lower boiling point VOCs, benzene and toluene, were trapped in fibrous Membrane higher that the Dense Membrane since they cause swelling in fiber morphology
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amine modified electrospun pim 1 ultrafine fibers for an efficient removal of methyl orange from an aqueous system
Applied Surface Science, 2018Co-Authors: Bekir Satilmis, Tamer UyarAbstract:Abstract Polymers of Intrinsic Microporosity (PIM-1) is a promising material for adsorption and separation applications. While PIM-1 displays high affinity for neutral species, it shows lack of interaction with charged molecules in an aqueous system due to non-polar nature of it. Functionalization of PIM-1 provides an advantage of tailoring the interaction ability as well as the adsorption performance of PIM-1 towards target pollutants. In this study, electrospun Polymer of Intrinsic Microporosity (PIM-1) fibrous Membrane (PIM-FM) was reacted with borane dimethyl sulfide complex to obtain amine modified PIM-1 fibrous Membrane (AM-PIM-FM). Furthermore, PIM-1 film, which is referred as PIM-1 Dense Membrane (PIM-DM), was also modified under the same conditions as a control material. Structural analyses have confirmed that nitrile groups of PIM-1 have been fully converted to amine group as a result of the reduction reaction. Average fiber diameter of parent PIM-1 fibers was found 2.3 ± 0.3 μm, and it remained almost the same after the amine modification. In addition, no physical damage has been observed on fiber structure based on the SEM analysis. Both amine modified PIM-1 Dense and fibrous Membranes became insoluble in common organic solvents. Before the modification, water contact angle of PIM-FM was 138 ± 2° which also remained almost the same after the modification, showing water contact angle of 131 ± 8°. The insolubility along with amine functionality make Membranes promising materials for adsorption of anionic dyes from wastewater. Here, dye (i.e. Methyl Orange) removal ability of AM-PIM-FM from an aqueous system was investigated and compared with parent PIM-1 (PIM-FM) as well as Dense Membrane form (AM-PIM-DM). AM-PIM-FM shows extremely higher adsorption capacity than that of PIM-FM and AM-PIM-DM. The maximum adsorption capacity of AM-PIM-FM was found 312.5 mg g−1 for Methyl Orange. Langmuir isotherm model was found more favorable for the adsorption. AM-PIM-FM was employed effectively in continuous adsorption/desorption studies for several times without having any damage on fiber morphology using batch adsorption process. Furthermore, AM-PIM-FM was successfully used as a molecular filter for the removal of methyl orange from an aqueous system. The results indicate that AM-PIM-FM could be a promising adsorbent for removal of anionic molecules from an aqueous system.
Eric Favre - One of the best experts on this subject based on the ideXlab platform.
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Membrane distillation md processes for water desalination applications can Dense selfstanding Membranes compete with microporous hydrophobic materials
Chemical Engineering Science, 2018Co-Authors: Deisy Lizeth Mejia Mendez, Christophe Castel, Cecile Lemaitre, Eric FavreAbstract:Abstract Membrane distillation (MD) is considered as a key technology for desalination applications. It shows indeed numerous advantages compared to reverse osmosis and other desalination processes (e.g. thermal driving force, no osmotic pressure effect on Membrane fluxes). Nevertheless, this technology still presents some issues, most notably due to pore wetting effects. This study proposes the use of a thin, self-standing Dense Membrane in place of microporous materials as a solution to avoid wetting in MD for water desalination. In a first step, a Membrane contactor model is developed based on mass and energy balances and the simulations are validated using experimental results obtained on hollow fiber modules with microporous Membranes. A comparative performance analysis is then achieved between a porous and a Dense Membrane module. A parametric study on the influence of Dense Membrane thickness and water permeability shows that a two fold increase in water flux, without significant impact on energy efficiency, is potentially achievable with thin and permeable Dense materials compared to microporous Membranes. Guidelines for the design of high-performance Dense Membrane modules for MD are finally proposed.
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a Dense Membrane contactor for intensified co2 gas liquid absorption in post combustion capture
Journal of Membrane Science, 2011Co-Authors: Phuc Tien Nguyen, Denis Roizard, Elsa Lasseuguette, Yaocihuatl Medinagonzalez, Jeanchristophe Remigy, Eric FavreAbstract:Abstract Membrane contactors based on microporous hydrophobic materials already offer remarkable performances for different separation applications at industrial scale, especially for gas–liquid mass transfer operations. Impressive process intensification effects can indeed be achieved in certain cases, due to the large interfacial area provided by hollow fiber Membranes. Nevertheless, depending on the Membrane and fluid properties, great differences in mass transfer can be obtained; undesirable effects due to liquid contact such as gradual changes in Membrane structure and/or partial wetting of the pores can dramatically affect mass transfer performances. Numerous studies have addressed these difficulties for one of the most attracting and challenging application of Membrane contactors: the absorption of CO 2 in a chemical solvent in order to achieve post-combustion CO 2 capture from flue gases. For this application, given the fast chemical reaction which takes place in the liquid phase, a highly permeable Membrane material is absolutely necessary. Additionally, the Membrane material has to withstand long term contact with a chemically reactive solvent (typically an amine such as monoethanolamine: MEA) and has to remain non wetted. A possible solution which prevents wetting problems together with a minimal impact on the Membrane mass transfer coefficient is reported in this study; the key idea is to make use of a composite Membrane based on a thin Dense skin, based on a highly permeable glassy polymer, coated on a microporous support. In a first step, screening tests have been performed in order to identify potential polymer candidates for the thin skin, combining a high CO 2 permeability and solvent (MEA) compatibility on long time scales. In a second step, composite hollow fibers with a thin skin (Teflon AF ® , PTMSP) coated on a porous support (PP) have been prepared and tested. The concept has been finally tested and validated at lab scale for CO 2 capture from a gas mixture into aqueous solutions of MEA with hollow fiber modules. Remarkably, the overall mass transfer performances of the composite fibers compete with the most permeable microporous Membranes classically proposed for Membrane contactor applications. The possible use of these novel composite fibers for other applications and the extension of the concept to different industrial situations are discussed.
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Dense Membrane permeation from the limitations of the permeability concept back to the solution diffusion model
Journal of Membrane Science, 2005Co-Authors: Guillain Mauviel, Cecile Vallieres, Denis Roizard, Julien Berthiaud, Eric FavreAbstract:Abstract In a recent publication, J.G. Wijmans [J.G. Wijmans, Process performance = Membrane properties + operating conditions, J. Membr. Sci. 220 (2003) 1–3] drew attention to the risk associated with a common practice in pervaporation: reporting experimental permeates fluxes without the corresponding operating conditions. The systematic use of the Membrane permeability, in place of the raw fluxes, clearly improves the comparison as well as the prediction of process performances. Nevertheless, this strategy does not generally lead to a single value for the permeability coefficient; moreover, discrepancies are often reported for systems which exhibit variable permeabilities. This work analyses the limitations of the permeability concept based on a preliminary case study limited to a single penetrant (propane permeation through a silicone rubber Membrane). In addition, it is shown that solution-diffusion model fundamentals enable experimental data reconciliation. This novel strategy is preferable when we wish to compare and compute the permeate flux on a rigorous basis.
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vacuum versus sweeping gas operation for binary mixtures separation by Dense Membrane processes
Journal of Membrane Science, 2004Co-Authors: Cecile Vallieres, Eric FavreAbstract:When a gaseous phase takes place at the downstream side of a Membrane separation process, two distinct options can be schematically operated in order to induce a driving force from that side: apply a lower pressure than the upstream one (thanks to a vacuum pump for instance), or exert a diluting effect by an inert gas sweep (under higher total downstream pressure conditions). The pros and cons of these two alternatives, particularly in terms of overall energy consumption, are often questioned, for instance for pervaporation applications where the first one (vacuum) is most often chosen but has never been systematically compared to the second one (sweeping gas). A simplified analysis of the above question is presented in this work. Based on a theoretical framework, which has been recently proposed, an easy to handle analytical solution to this problem is obtained. This expression enables the energy consumption under similar separation performances to be computed, providing that the permeabilities of the two compounds of the feed mixture remain constant. More specifically, it is shown that the energy consumption versus total downstream pressure curve shows invariably an asymmetrical bell shape with a maximum located at a fixed position. Operating conditions leading to minimal work of pumping will always be located at one of the two limits of the curve, that is to say either for low vacuum or high flowrate gas sweeping conditions. Nevertheless, taking into account the overall work of separation (i.e. the work needed for pure compounds recovery) clearly plays in favor of the vacuum operation.
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separation of binary mixtures by Dense Membrane processes influence of inert gas entrance under variable downstream pressure conditions
Chemical Engineering Science, 2003Co-Authors: Cecile Vallieres, Xavier Arnold, Eric Favre, Denis RoizardAbstract:The influence of an inert gas on the separation performances of a Dense polymeric Membrane module working under partial vacuum on the downstream side, such as possibly encountered in gas permeation, vapor permeation or pervaporation, has been investigated through an experimental and theoretical study. A whole range of situations on the downstream side, covering ideal vacuum pumping (i.e. zero downstream pressure under leak free conditions) to inert gas sweeping under atmospheric pressure has been tested. A theoretical framework, previously developed for single permeant situation has been extended to the multicomponent case. The separation of methanol and 2-propanol by a Dense silicone rubber Membrane confirms the ability of this simple modelling strategy to offer quantitative predictions of the permeate composition under variable downstream pressure and inert gas flowrate conditions. Based on this observation, the implications of an inert gas contribution on pervaporation or gas separation operation are discussed, particularly in relationship to the global energy consumption of the system or to analytical devices making use of a gas sweep.
Neal K Devaraj - One of the best experts on this subject based on the ideXlab platform.
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lipid sponge droplets as programmable synthetic organelles
Proceedings of the National Academy of Sciences of the United States of America, 2020Co-Authors: Ahanjit Bhattacharya, Henrike Niederholtmeyer, Kira A Podolsky, Rupak Bhattacharya, Jingjin Song, Roberto J Brea, Chuhsien Tsai, Sunil K Sinha, Neal K DevarajAbstract:Living cells segregate molecules and reactions in various subcellular compartments known as organelles. Spatial organization is likely essential for expanding the biochemical functions of synthetic reaction systems, including artificial cells. Many studies have attempted to mimic organelle functions using lamellar Membrane-bound vesicles. However, vesicles typically suffer from highly limited transport across the Membranes and an inability to mimic the Dense Membrane networks typically found in organelles such as the endoplasmic reticulum. Here, we describe programmable synthetic organelles based on highly stable nonlamellar sponge phase droplets that spontaneously assemble from a single-chain galactolipid and nonionic detergents. Due to their nanoporous structure, lipid sponge droplets readily exchange materials with the surrounding environment. In addition, the sponge phase contains a Dense network of lipid bilayers and nanometric aqueous channels, which allows different classes of molecules to partition based on their size, polarity, and specific binding motifs. The sequestration of biologically relevant macromolecules can be programmed by the addition of suitably functionalized amphiphiles to the droplets. We demonstrate that droplets can harbor functional soluble and transMembrane proteins, allowing for the colocalization and concentration of enzymes and substrates to enhance reaction rates. Droplets protect bound proteins from proteases, and these interactions can be engineered to be reversible and optically controlled. Our results show that lipid sponge droplets permit the facile integration of Membrane-rich environments and self-assembling spatial organization with biochemical reaction systems.
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lipid sponge droplets as programmable synthetic organelles
bioRxiv, 2020Co-Authors: Ahanjit Bhattacharya, Henrike Niederholtmeyer, Kira A Podolsky, Rupak Bhattacharya, Jingjin Song, Roberto J Brea, Chuhsien Tsai, Sunil K Sinha, Neal K DevarajAbstract:Abstract Living cells segregate molecules and reactions in various subcellular compartments known as organelles. Spatial organization is likely essential for expanding the biochemical functions of synthetic reaction systems, including artificial cells. Many studies have attempted to mimic organelle functions using lamellar Membrane-bound vesicles. However, vesicles typically suffer from highly limited transport across the Membranes and an inability to mimic the Dense Membrane networks typically found in organelles such as the endoplasmic reticulum. Here we describe programmable synthetic organelles based on highly stable nonlamellar sponge phase droplets that spontaneously assemble from a single-chain galactolipid and non-ionic detergents. Due to their nanoporous structure, lipid sponge droplets readily exchange materials with the surrounding environment. In addition, the sponge phase contains a Dense network of lipid bilayers and nanometric aqueous channels, which allows different classes of molecules to partition based on their size, polarity, and specific binding motifs. The sequestration of biologically relevant macromolecules can be programmed by the addition of suitably functionalized amphiphiles to the droplets. We demonstrate that droplets can harbor functional soluble and transMembrane proteins, allowing for the co-localization and concentration of enzymes and substrates to enhance reaction rates. Droplets protect bound proteins from proteases, and these interactions can be engineered to be reversible and optically controlled. Our results show that lipid sponge droplets permit the facile integration of Membrane-rich environments and self-assembling spatial organization with biochemical reaction systems. Significance statement Organelles spatially and temporally orchestrate biochemical reactions in a cell to a degree of precision that is still unattainable in synthetic reaction systems. Additionally, organelles such as the endoplasmic reticulum (ER) contain highly interconnected and Dense Membrane networks that provide large reaction spaces for both transMembrane and soluble enzymes. We present lipid sponge droplets to emulate the functions of organelles such as the ER. We demonstrate that lipid sponge droplets can be programmed to internally concentrate specific proteins, host and accelerate biochemical transformations, and to rapidly and reversibly sequester and release proteins to control enzymatic reactions. The self-assembled and programmable nature of lipid sponge droplets will facilitate the integration of complex functions for bottom up synthetic biology.