Membranes最新文献

{"title":"Effects of Barium Excess on the Performance of Multilayer Microtubular Proton Ceramic Electrochemical Hydrogen Pumps with Ba_xCe_0.7Zr_0.1Y_0.1Yb_0.1O_3-δ (x = 1.05, 1.10, 1.15).","authors":"Shao Zhang, Lihui Wang, Congcong Li, Mingming Wang, Zhigang Wang, Xiaoyao Tan","doi":"10.3390/membranes16090307","DOIUrl":"10.3390/membranes16090307","url":null,"abstract":"<p><p>A series of Ba-excess Ba_xCe_0.7Zr_0.1Y_0.1Yb_0.1O_3-δ (B_xCZYYb, x = 1.05, 1.10, 1.15) was employed as electrolytes. Multilayer microtubular protonic ceramic electrochemical hydrogen pumps (PCEHPs) with a current collector/anode/electrolyte/cathode/current collector architecture were fabricated by a triple-layer one-step co-spinning and co-sintering method. Their hydrogen separation performance was systematically investigated over the temperature range of 200-400 °C. The results show that the hydrogen pump employing the B_1.05CZYYb electrolyte delivers the optimal performance. At 250 °C and a feed H₂ concentration of 30 vol%, the hydrogen permeation flux achieves 1.01 mL min^-1 cm^-2, with Faradaic efficiency maintained above 95%. EDS line-scan results reveal the presence of Ni-rich precipitates on grain surfaces in the co-sintered electrolyte layer. It is speculated that, under the co-sintering conditions, excessive Ba may induce lattice distortion and reduce Ni solubility in the perovskite lattice, thereby promoting Ni exsolution at grain surfaces; the precipitated Ni could, in turn, hinder proton conduction and increase the ohmic resistance. These findings suggest that the hydrogen-permeation performance of multilayer PCEHPs is governed by the combined effect of Ba excess and Ni rather than by Ba doping alone. This work provides a valid experimental basis and theoretical reference for component optimization and structural design of high-performance co-sintered microtubular PCEHP devices.</p>","PeriodicalId":18410,"journal":{"name":"Membranes","volume":"16 9","pages":""},"PeriodicalIF":4.2,"publicationDate":"2026-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13609753/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149039596","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Sacrificial CaCO₃ Precoating Preserves Fouling Reversibility of Ceramic Nanofiltration During Filtration of Real Wastewater Treatment Plant Effluent.","authors":"Yuke Li, Luuk C Rietveld, Sebastiaan G J Heijman","doi":"10.3390/membranes16090306","DOIUrl":"10.3390/membranes16090306","url":null,"abstract":"<p><p>Fouling of ceramic nanofiltration (NF) membranes becomes difficult to reverse when complex wastewater constituents accumulate directly on the selective layer. Sacrificial precoating may spatially separate foulant deposition from the membrane surface, but its effectiveness under real wastewater conditions remains insufficiently understood. A single CaCO₃ precoating step was evaluated over three consecutive filtration-cleaning cycles using municipal wastewater treatment plant (WWTP) effluent. During three consecutive 6-h filtration cycles, precoating substantially improved the reversibility of hydraulic fouling. Permeability recovery reached 92% after the first cleaning and was 80% after the second cleaning, whereas the uncoated membrane recovered only 34% after the first cleaning and subsequently showed little effective recovery. The precoated system also exhibited markedly lower irreversible hydraulic resistance. In addition to fouling control, the mineral precoat altered solute removal in the complex wastewater matrix: DOC removal remained approximately 90%, while apparent phosphate removal increased from 38% for the uncoated membrane to 90% for the precoated system. These findings demonstrate that CaCO₃ precoating acts as a sacrificial interfacial layer that preserves fouling reversibility during ceramic NF treatment of real WWTP effluent, while mineral-solute interactions may additionally contribute to the apparent removal of selected inorganic solutes.</p>","PeriodicalId":18410,"journal":{"name":"Membranes","volume":"16 9","pages":""},"PeriodicalIF":4.2,"publicationDate":"2026-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13609071/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149039609","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Regulation of Membrane Association and Downstream Effector Interaction of K-Ras by Its Hypervariable Region.","authors":"Anda Trifan, Hossein Omidi Ardali, Josh V Vermaas, Till Rudack, Emad Tajkhorshid","doi":"10.3390/membranes16090304","DOIUrl":"10.3390/membranes16090304","url":null,"abstract":"<p><p>The small GTPase Ras, a central switch in signal transduction of cell growth, is a crucial element in the development of many forms of cancer. Recent studies have shown that membrane association of Ras is essential to its downstream effector recruitment and signal transduction. Here we investigate the membrane association and interaction of K-Ras4B, the most frequently found Ras isoform in tumor cells, using all-atom molecular dynamics simulations totaling 8.5 μs. We find that the isoform-specific, farnesylated hypervariable region (HVR) of Ras plays an important role in the organization and oligomerization of its globular domain (G-domain) on the surface of the membrane. We show that the overall pose of the Ras G-domain on the membrane can be determined by its HVR. The HVR thus can control downstream effector binding by positioning the G-domain on the membrane in a specific orientation. Furthermore, we observe that the HVR alone already transiently dimerizes in the membrane and recruits negatively charged phosphatidylserine lipids around the K-Ras isoform-specific poly-lysine region. The observed HVR dimerization potentially can initiate the dimerization of the full K-Ras, which is essential for downstream effector signaling via various pathways. These atomistic details behind the molecular mechanism of the HVR provide novel insight into Ras interaction with membrane and its availability for downstream effectors.</p>","PeriodicalId":18410,"journal":{"name":"Membranes","volume":"16 9","pages":""},"PeriodicalIF":4.2,"publicationDate":"2026-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13609897/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149039588","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Entropy-Driven Initiation and Cytoskeletal Viscoelasticity in Endocytosis: An Onsager Variational Framework.","authors":"Jinjie Liu, Zhongcan Ouyang, Hao Wu","doi":"10.3390/membranes16090305","DOIUrl":"10.3390/membranes16090305","url":null,"abstract":"<p><p>Receptor-mediated endocytosis requires a particle to approach the cell membrane to within a few nanometers before ligand-receptor binding can occur. Existing continuum models often start from an already established contact and do not explicitly describe how crowding particles on the extracellular side influence the distribution of the particle near the membrane. We examine entropic depletion forces as one possible nonspecific contribution to this initial approach. For ideal depletants, the Asakura-Oosawa excluded-volume construction gives an exact depletion potential for the planar geometry before contact. The potential and force vanish continuously at the onset of excluded-volume overlap. This interaction provides a possible contribution to membrane proximity before specific binding, while its extension to curved wrapping geometries requires additional approximation. Within a reduced continuum model, we combine depletion attraction, ligand-receptor binding, membrane deformation, and cytoskeletal viscoelastic dissipation. The viscoelastic contact is formulated through a hereditary integral and a standard linear solid. The kinetic model gives a conditional minimum ligand density for complete engulfment, a finite particle-size window, and a stiffness-dependent upper limit. When the stationary radius lies inside the domain of finite positive wrapping times, the estimated wrapping time has a minimum at a radius that decreases with increasing binding energy density. At fixed viscosity and other independent parameters, the same time approximation predicts slower wrapping as cell stiffness increases. The two positive roots defining the size window merge at a limiting parameter value, which characterizes closure of the admissible size interval. Depletion attraction is interpreted as one possible contribution to particle-membrane association, alongside electrostatic interactions, steric effects, and membrane fluctuations. The present analysis identifies how nonspecific attraction, specific adhesion, and mechanical resistance can contribute to different stages of membrane wrapping.</p>","PeriodicalId":18410,"journal":{"name":"Membranes","volume":"16 9","pages":""},"PeriodicalIF":4.2,"publicationDate":"2026-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13609808/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149039622","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Three-Dimensional Framework for Rational Ion Separation with Polymeric Membrane Systems.","authors":"George Bess-Palacios, Guillermo González-Sánchez, Claudia Alejandra Hernández-Escobar, Claudia Ivone Piñón-Balderrama, Miguel Alonso Orozco-Alvarado, América Susana Mares-García, Anayansi Estrada-Monje, Erasto Armando Zaragoza-Contreras","doi":"10.3390/membranes16090302","DOIUrl":"10.3390/membranes16090302","url":null,"abstract":"<p><p>This review treats selective ion separation in polymeric membrane systems as a design problem rather than as a fixed material property. To address the gap between laboratory performance and process-level relevance, a three-dimensional analytical framework that integrates transport mechanism, dynamic structural state, and separation-matrix complexity is proposed. Five research streams are compared: polymer inclusion membranes, ion-exchange membranes and electrodialysis, nanostructured and subnanometric frameworks, composite architectures, and polymer inclusion membrane - electrodialysis (PIM-ED) hybrids. The comparison shows that selectivity is governed not only by the nominal membrane mechanism, but also by hydration-driven structural changes and by the complexity of the operating matrix. Overall, the framework provides a common basis for interpreting selectivity, comparing membrane families, and guiding rational design for ion-separation processes.</p>","PeriodicalId":18410,"journal":{"name":"Membranes","volume":"16 9","pages":""},"PeriodicalIF":4.2,"publicationDate":"2026-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13609601/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149039462","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Optimization of 2D Ag-MBene-Modified Polyethersulfone Ultrafiltration Membranes for Enhanced Water Treatment Performance.","authors":"Asam Amin Almulla, Fikri T Dweiri","doi":"10.3390/membranes16090303","DOIUrl":"10.3390/membranes16090303","url":null,"abstract":"<p><p>Modified PES ultrafiltration membranes containing Ag-MBene nanoparticles were developed via the non-solvent-induced phase separation (NIPS) technique and evaluated for tertiary-treated sewage (TSE) filtration applications. This study aims to establish an integrated understanding of membrane structure, properties, and performance by correlating morphology, roughness, hydrophilicity, porosity, permeability, antifouling properties, and pollutant rejection capabilities. Ag-MBene nanomaterials were incorporated into the PES membrane at various loading concentrations to increase the membrane hydrophilicity and antifouling characteristics. The detailed characterization of membrane samples was performed using SEM, AFM, EDS, FTIR, contact angle analysis, and porosity evaluation. The membranes exhibited distinct structural features after the addition of Ag-MBene nanomaterials. SEM analysis revealed enhanced macropore formation and increased pore interconnectivity at a relatively moderate loading concentration of nanoparticles. AFM analysis further confirmed progressive membrane roughness enhancement after incorporating Ag-MBene particles. The contact angle decreased from 81.2° (UF00) to 47.3° (UF1.5), indicating enhanced hydrophilicity of the modified membranes. UF0.5 exhibited the most balanced overall performance due to optimized pore morphology, improved wettability, and uniform nanoparticle dispersion. The modified membranes also exhibited enhanced flux performance, more reversible fouling behavior, and improved chemical oxygen demand (COD)/total suspended solids (TSS) removal efficiency than pristine membranes. ANOVA revealed significant differences among various membranes (<i>p</i> < 0.05), and the UF0.5 configuration was identified as the optimal membrane based on its balanced structural and performance characteristics. These findings demonstrate that balanced optimization of membrane morphology, hydrophilicity, and nanoparticle dispersion is essential for maximizing ultrafiltration performance.</p>","PeriodicalId":18410,"journal":{"name":"Membranes","volume":"16 9","pages":""},"PeriodicalIF":4.2,"publicationDate":"2026-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13609314/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149039613","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Conducting Polymer-Based Nanofluidic Membranes for Osmotic Energy Conversion.","authors":"Sinuo Zhou, Chengyang Jia, Ying Zhang, Boyu Sun, Xin Xi, Shuhan Yang, Lipeng Liu, Guoyu Zhang, Xiaoyan Nie, Qiang Wang, Siqi Liu, Yanan Xie, Zhenhang Wang","doi":"10.3390/membranes16090301","DOIUrl":"10.3390/membranes16090301","url":null,"abstract":"<p><p>Osmotic energy conversion (blue energy), serving as a sustainable marine renewable energy source, converts Gibbs free energy originating from salt concentration differences into electric power by virtue of ion-selective nanofluidic membranes. Conventional commercial ion-exchange polymer membranes suffer from inherent limitations, including low transmembrane flux, insufficient ion permselectivity, severe interfacial concentration polarization, poor salt tolerance, and unsatisfactory long-term structural stability. These drawbacks greatly restrict the energy conversion efficiency and large-scale engineering application of reverse electrodialysis (RED). Conductive polymers (CPs), mainly including polypyrrole (PPy), polyaniline (PANI), polythiophene (PTh), and their derivatives, possess the distinctive merits of tunable surface charge density and polarity, outstanding electronic conductivity, facile nanochannel structural regulation, and reversible redox responsiveness, making them ideal building blocks for advanced nanofluidic membranes for high-efficiency osmotic energy conversion. This review summarizes recent progress in the fabrication of conductive polymer-based nanofluidic membranes, comprehensively compares the osmotic output performance of typical CP material systems, and discusses the core metrics of osmotic energy conversion output performance. By providing an overview of these developments, this review aims to offer insights into the future development of conductive polymer-based nanofluidic membranes for osmotic energy conversion.</p>","PeriodicalId":18410,"journal":{"name":"Membranes","volume":"16 9","pages":""},"PeriodicalIF":4.2,"publicationDate":"2026-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13608889/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149039567","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Eco-Friendly Solvent-Based Fabrication of Single-Layer and Polydopamine-Modified Bilayer PVDF-HFP Membranes.","authors":"Tridwip Sen, Eesh Kulshrestha, Muhammad Usman Yousaf, Minwoo Jung, Tequila A L Harris, Isabel C Escobar","doi":"10.3390/membranes16090300","DOIUrl":"10.3390/membranes16090300","url":null,"abstract":"<p><p>Polymeric membrane systems have emerged as an effective approach for water separations due to their high separation efficiency, simplicity, and adaptability to a wide range of water treatment applications. However, traditional membrane fabrication processes often rely on toxic organic solvents, such as N-methyl-2-pyrrolidone (NMP) and dimethylacetamide (DMAc), which pose environmental and health risks. Eco-friendly solvents have been investigated as an alternative to traditional toxic solvents. This study investigates the fabrication and performance of polymeric membranes using eco-friendly solvent systems, with a focus on bilayer membranes designed to improve separation performance over traditional single-layer membranes. Membranes were fabricated using eco-friendly solvents, Rhodiasolv© PolarClean and gamma-valerolactone in combination with polymers polysulfone (PSf) and poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP). Membranes were fabricated using nonsolvent-induced phase separation (NIPS) through doctor blade extrusion (DBE) and slot-die coating (SDC) methods in order to compare traditional laboratory-scale casting methods (DBE) with scalable fabrication techniques (SDC). Bilayer membranes were investigated to address limitations presented by single-layer membranes, with polydopamine (PDA) incorporated as an adhesion-promoting additive. Membrane characterization included scanning electron microscopy (SEM), contact angle measurements, and tensile testing, along with water permeability and solute rejection tests. Results showed that polymer concentration and casting method influenced permeability and solute rejection, with the SDC bilayers reaching the highest initial BSA rejection. Filtration used deionized water and model aqueous feeds containing 100 ppm NaCl, 100 ppm CaCl₂, and 100 ppm bovine serum albumin (BSA).</p>","PeriodicalId":18410,"journal":{"name":"Membranes","volume":"16 9","pages":""},"PeriodicalIF":4.2,"publicationDate":"2026-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13609762/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149039556","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Full-Scale Multistage Pressure-Retarded Osmosis for Osmotic Energy Generation: Optimization of Specific and Net Energy Production.","authors":"Daniel Suárez-Alfonso, Alejandro Ruiz-García","doi":"10.3390/membranes16090299","DOIUrl":"10.3390/membranes16090299","url":null,"abstract":"<p><p>Salinity gradient energy, also known as blue energy, is a clean and renewable option for electricity generation with no direct CO₂ emissions. Among the available technologies, pressure-retarded osmosis (PRO) stands out, although its large-scale implementation is not yet economically viable, so predictive models are essential to assess its real potential. In the present work, a multistage PRO system of up to three stages, with one-three hollow-fiber membrane modules (HFMMs) arranged in series per stage, was simulated and the operating conditions were optimized. The model accounts for axial pressure drops, feed concentration and draw dilution along each module, considering two salinity gradients of 29.5 and 59.5 g L^-1. The maximum net specific energy generation reached 421.48 Wh m^-3 with three stages under the 59.5 g L^-1 gradient. Adding HFMMs in series benefited the two-stage system but slightly penalized the three-stage one, and the net specific energy decreased monotonically as the ratio of pressure vessels between the first and the second stage increased. At least three stages are therefore required for a full-scale PRO system to become a net energy producer at moderate salinity gradients, and further energy should be sought through additional staging rather than through longer series.</p>","PeriodicalId":18410,"journal":{"name":"Membranes","volume":"16 9","pages":""},"PeriodicalIF":4.2,"publicationDate":"2026-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13609321/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149039579","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Effects of Ca²⁺ on Membrane Potential with Altered Function of NALCN and K2P Channels.","authors":"Youngwoo Kim, Jiwoo Kim, Robin L Cooper","doi":"10.3390/membranes16090298","DOIUrl":"10.3390/membranes16090298","url":null,"abstract":"<p><p>Cells exhibit a membrane potential due to the differential distribution of ions and the density of channels, pumps, and exchangers. It is known in larval <i>Drosophila</i> that the membrane potential gravitates towards the equilibrium potential of K⁺ due to the high density of K2P channels. Higher extracellular Ca²⁺ ([Ca²⁺]_o) tends to drive the resting membrane potential to a more negative state, while lowering it has an opposite effect. The expression of the K2P channel and NALCN was altered genetically to determine the sensitivity to changes in [Ca²⁺]_o, and computational simulations using the theoretical Goldman-Hodgkin-Katz equation allowed estimating changes in ion (Na⁺) permeability due to altered function of the NALCN. Increasing [Ca²⁺]_o hyperpolarized the membrane potential, and decreasing [Ca²⁺]_o depolarized it, likely because Ca²⁺ ions block NALCN. An accessory protein to NALCN and NALCN itself were targeted by RNAi. Overexpression of K2P channels and decreased NALCN function reduced the effect of altered [Ca²⁺]_o on membrane potential. Given the limited understanding of how altered membrane potentials affect cells, this study provides a foundation for future investigations into how cells respond to variations in [Ca²⁺]_o under altered K2P and NALCN expression.</p>","PeriodicalId":18410,"journal":{"name":"Membranes","volume":"16 9","pages":""},"PeriodicalIF":4.2,"publicationDate":"2026-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13609646/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149039666","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}