Pure-silica MFI zeolite membrane by cooperative templating approach for ethanol-water separation

Pure-silica MFI zeolite membrane composed of intergrown four prism crystals was fabricated by using tetrabutylammonium (TBA⁺) and tetraethylammonium (TEA⁺) as cooperating templates and the induced function of MFI seeds under synthesis solution with molar composition of 1TEOS:0.2TBAOH:0.2TEABr:180H₂O. The ethanol/water separation factor was 64 with a flux of 1.40 kg m⁻² hr⁻¹ for 5 wt% ethanol/water mixture at 60°C. In contrast, single TBAOH and TEAOH template led to formation of uncontinuous MEL and MFI membrane respectively, without ethanol-selectivity. The behavior of quaternary ammonium (TBA⁺ and TEA⁺) varied in different system: (a) In “TBA⁺+ TEA⁺” system, TBA⁺ and TEA⁺ were incorporated into MFI zeolite channel simultaneously; (b) In “TPA⁺+ M⁺” system (M = TEA or TBA), either TEA⁺ or TBA⁺ could not be occluded into channel, however, appropriate amount of TBA⁺ could accelerate membrane crystallization, meanwhile increase in TEA⁺ slowed down crystallization rate of MFI membrane. This work extends the alternative preparation approaches of ethanol perm-selective MFI membrane.     

Cation adsorption at a distearoylphosphatidic acid layer adsorbed at a liquid/liquid interface

The interfacial behaviour of tetraethylammonium cations (TEA⁺) at a liquid-liquid interface modified with an anionic phospholipid layer, distearoyl phosphatidic acid (DSPA), is analysed, with the purpose of characterising the permeation properties of the film. The TEA⁺ concentration in aqueous solution and the amount of DSPA solution employed to generate the lipidic layer, were varied. The results indicate that the layer is tightly compact and the transfer of TEA⁺ cations by permeation does not take place. Instead of this, TEA⁺ ions adsorb at the polar head groups of DSPA, and these adsorbed cations could be acting as nucleation centres of DSPA molecules when the DSPA amount is low.     

Effects of salt on homogeneous succinoylation of lignocellulosic fibers in dimethyl sulfoxide/tetraethylammonium chloride under mild condition

Effects of salt in the homogeneous succinoylation of ball milled mulberry wood in dimethyl sulfoxide (DMSO)/tetraethylammonium chloride (TEACl) was investigated using viscometry and two‐dimensional nuclear overhauser effect NMR spectroscopy (2D NOESY). The intrinsic viscosity of mulberry wood solution strongly depends on the TEACl dosage indicating that the change in hydrodynamic size of polymers caused by the interactions between salt and polymers in solution. 2D NOESY spectra reveal that TEA⁺ cations bind to the cellobiose in DMSO by the interactions between methenyl of TEA⁺ and C(1)/C(1′) group of cellobiose and the intensities of the crosspeaks increased with an increase in TEACl dosage. Taking cellobiose as a model compound for cellulose, it can be expected that TEA⁺ cations and cellulose forms a polyelectrolyte‐like complex. The yields of homogeneous succinoylation of mulberry wood in DMSO/TEACl benefits from the interactions between TEA⁺ cations and cellulose evidenced by weight percent gain, Fourier transform infrared spectra as well as CP/MAS ¹³C‐NMR spectra. © VC 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41912.     

Electrochemical study of flunitrazepam partitioning into zwitterionic phospholipid monolayers

The effect of flunitrazepam (FNTZ) on molecular packing of distearoylphosphatidylcholine (DSPC) and distearoylphosphatidylethanolamine (DSPE) monolayers adsorbed at the water/1,2-dichloroethane interface was investigated using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS).The interfacial packing of the monolayer was estimated by the analysis of the voltammetric transfer of tetraethylammonium cation (TEA⁺) from the aqueous to the organic phase in the presence of different cations (Li⁺, Ca²⁺ and K⁺) in water. An important blocking of the transfer process was observed in the case of DSPE monolayer when the aqueous phase contained Li⁺ and Ca²⁺cations indicating a highly ordered structure. FNTZ produced an enhancement of this blocking effect. EIS experiments evidenced the presence of different domains in the monolayer when FNTZ was present. The covered zones of the monolayer exhibited higher compactness compared with the corresponding in absence of FNTZ. TEA⁺ transfer process does not occur across so packed regions but through the very small uncovered zones (pores), resulting in a decrease of the transfer current. This blocking effect of DSPE monolayer containing FNTZ was not observed in the case of DSPC. It was concluded that FNTZ accumulation at the interface induces lateral interactions between DSPE molecules resulting in a highly condensed monolayer.     

Cation transfer across a hydrogel/organic phase: Effect of cation size, hydrophobicity and acid-base properties

The transfers of tetraethylammonium (TEA⁺) and protonated triflupromazine (HTFP⁺) through a hydrogel/liquid interface (g/o) and a liquid/liquid interface (w/o) were compared using cyclic voltammetry. After the two phases were put in contact, the behavior of each molecule was analyzed at different pH values and at different time points. The gel induces hydrophobic and electrostatic interactions with TEA⁺ and HTFP⁺, shifting the peak potentials to more positive values. The diffusion coefficients, D, in both phases (g and w) at different pH values were calculated. In the case of TEA⁺, the D value remains constant in both systems. However, the D value of HTFP⁺ is lower in the gel phase than in the liquid phase.HTFP⁺ is transferred from the aqueous phase to the organic phase via a direct mechanism that involves coupled acid-base and partition processes. At the g/o interface, the coupled chemical reactions of HTFP⁺ were inhibited by the drug/gel interaction. The results demonstrate that the g/o system could be used as a model to study the controlled release of charged drugs.     

Human Omental Mesothelial Cells Impart an Immunomodulatory Landscape Impeding B- and T-Cell Activation

Mesothelial cells form the mesothelium, a simple epithelium lining the walls of serous cavities and the surface of visceral organs. Although mesothelial cells are phenotypically well characterized, their immunoregulatory properties remain largely unknown, with only two studies reporting their capacity to inhibit T cells through TGF-β and their consumption of L-arginine by arginase-1. Whether human mesothelial cells can suppress other immune cells and possess additional leukosuppressive mechanisms, remain to be addressed to better delineate their therapeutic potential for cell therapy. Herein, we generated secretomes from omental mesothelial cells (OMC) and assess their capacity to inhibit lymphocytes proliferation, suppress activated T and B cells, as well as to modify macrophage activation markers. The secretome from mesenchymal stromal cells (MSC) served as a control of immuno-suppression. Although OMC and MSC were phenotypically divergent, their cytokine secretion patterns as well as expression of inflammatory and immunomodulary genes were similar. As such, OMC- and MSC-derived secretomes (OMC-S and MSC-S) both polarized RAW 264.7 macrophages towards a M2-like anti-inflammatory phenotype and suppressed mouse and human lymphocytes proliferation. OMC-S displayed a strong ability to suppress mouse- and human-activated CD19⁺/CD25⁺ B cells as compared to MSC-S. The lymphosuppressive activity of the OMC-S could be significantly counteracted either by SB-431542, an inhibitor of TGFβ and activin signaling pathways, or with a monoclonal antibody against the TGFβ1, β2, and β3 isoforms. A strong blockade of the OMC-S-mediated lymphosuppressive activity was achieved using L-NMMA, a specific inhibitor of nitric oxide synthase (NOS). Taken together, our results suggest that OMC are potent immunomodulators.     

Properties of Transport Mediated by the Human Organic Cation Transporter 2 Studied in a Polarized Three-Dimensional Epithelial Cell Culture Model

The renal secretory clearance for organic cations (neurotransmitters, metabolism products and drugs) is mediated by transporters specifically expressed in the basolateral and apical plasma membrane domains of proximal tubule cells. Here, human organic cation transporter 2 (hOCT2) is the main transporter for organic cations in the basolateral membrane domain. In this study, we stably expressed hOCT2 in Madin-Darby Canine Kidney (MDCK) cells and cultivated these cells in the presence of an extracellular matrix to obtain three-dimensional (3D) structures (cysts). The transport properties of hOCT2 expressed in MDCK cysts were compared with those measured using human embryonic kidney cells (HEK293) stably transfected with hOCT2 (hOCT2-HEK cells). In the MDCK cysts, hOCT2 was expressed in the basolateral membrane domain and showed a significant uptake of the fluorescent organic cation 4-(4-(dimethylamino)styryl)-N-methylpyridinium (ASP⁺) with an affinity (K_m) of 3.6 ± 1.2 µM, similar to what was measured in the hOCT2-HEK cells (K_m = 3.1 ± 0.2 µM). ASP⁺ uptake was inhibited by tetraethylammonium (TEA⁺), tetrapentylammonium (TPA⁺), metformin and baricitinib both in the hOCT2-HEK cells and the hOCT2- MDCK cysts, even though the apparent affinities of TEA⁺ and baricitinib were dependent on the expression system. Then, hOCT2 was subjected to the same rapid regulation by inhibition of p56^lck tyrosine kinase or calmodulin in the hOCT2-HEK cells and hOCT2- MDCK cysts. However, inhibition of casein kinase II regulated only activity of hOCT2 expressed in MDCK cysts and not in HEK cells. Taken together, these results suggest that the 3D cell culture model is a suitable tool for the functional analysis of hOCT2 transport properties, depending on cell polarization.     

Flunitrazepam effect on distearoylphosphatidylglycerol, cholesterol and distearoylphosphatidylglycerol + cholesterol mixed monolayers structure at a DCE/water interface

The effect of Flunitrazepam (FNTZ) on molecular packing of distearoylphosphatidylglycerol (DSPG), cholesterol (CHOL) monolayers and DSPG + CHOL mixed monolayers adsorbed at the water/1,2-dichloroethane interface was investigated using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS).The interfacial packing of the monolayer was estimated by the analysis of the voltammetric transfer of tetraethylammonium cation (TEA⁺) from the aqueous to the organic phase in the presence of different cations (Li⁺, Ca²⁺ and K⁺) in water. An important blocking of the transfer process was observed in the case of DSPG monolayer when the aqueous phase contained Li⁺ and Ca²⁺ cations indicating a highly ordered structure. EIS experiments evidenced that these cations adsorb at polar head group leading to a decrease in interfacial dielectric constant. FNTZ produced an enhancement of this blocking effect. When K⁺ was employed as aqueous electrolyte, no blocking effect of DSPG monolayer with or without FNTZ was observed. It was concluded that FNTZ induces lateral interaction with DSPG molecules in highly structured monolayers in which the negative charge of polar head groups is neutralized by cation adsorption.An interesting substitution effect of FNTZ was observed in monolayers containing CHOL.     

On the electric double-layer structure at carbon electrode/organic electrolyte solution interface analyzed by ac impedance and electrochemical quartz-crystal microbalance responses

ac impedance and electrochemical quartz crystal microbalance (EQCM) techniques have been applied to analyze the structure of electric double-layer formed at carbon/organic electrolyte solution interface using a sputtered carbon electrode. The mass changes caused by electrochemical adsorption (accumulation) of ions have been estimated in the solutions of propylene carbonate (PC) dissolving tetrafluoroborate (BF₄⁻) salts of lithium (Li⁺), tetraethylammonium (TEA⁺) and tetra-n-butylammonium (TBA⁺) cations. The observed mass changes during the cathodic polarization in the solutions containing TEA⁺ and TBA⁺ were well consistent with those expected by the calculation based on mono-layer adsorption of the cations with giving the consideration to the surface roughness. On the other hand, the mass change observed in the solution containing Li⁺ salt showed that the solvation of Li⁺ with three or four molecules of PC would be the charge compensation species at the interface. Comparison of the quantity of the electricity passed during the EQCM measurements with that from theoretical calculation with simple Helmholtz-layer model revealed that the major part of the double-layer capacitance would be based on the electrostatic polarization of the solvent molecule directly adsorbed at the carbon surface.     

Flow-injection amperometry at microfabricated silicon-based μ-liquid-liquid interface arrays

Geometrically regular silicon membrane-based micropore arrays were employed for defined arrays of micrometer-sized interfaces between two immiscible electrolyte solutions (μITIES). These were incorporated into a poly(tetrafluoroethylene) (PTFE) hydrodynamic cell. Electrochemistry at the μITIES array was undertaken following gellification of the organic phase using polyvinyl chloride (PVC) and flowing an aqueous phase over the array surface. Cyclic voltammetric characterization of asymmetric diffusion profiles on either side of the μITIES was accomplished under flowing conditions using positively and negatively charged (TEA⁺ and 4-OBSA⁻, respectively) model analyte species. Incorporation of an ionophore (dibenzo-18-crown-6 ether) into the organogel allowed the ion-transfer detection of two oligopeptides (phenylalanine dipeptide and lysine dipeptide) within the available potential window under stationary and flowing conditions. Flow rate studies with TEA⁺ indicated that the amperometric peak currents do not obey the Levich equation, due to diffusion dominating the mass transport, as opposed to convection. The influence of the applied potential () on the amperometric response of the oligopeptides was studied and hydrodynamic voltammograms (HDVs) for the individual oligopeptides were subsequently constructed. The data presented provide a basis for the use of silicon membrane-based μITIES arrays in flow analytical methods.     

Angulin-1 (LSR) Affects Paracellular Water Transport,However Only in Tight Epithelial Cells

Water transport in epithelia occurs transcellularly (aquaporins) and paracellularly (claudin-2, claudin-15). Recently, we showed that downregulated tricellulin, a protein of the tricellular tight junction (tTJ, the site where three epithelial cells meet), increased transepithelial water flux. We now check the hypothesis that another tTJ-associated protein, angulin-1 (alias lipolysis-stimulated lipoprotein receptor, LSR) is a direct negative actuator of tTJ water permeability depending on the tightness of the epithelium. For this, a tight and an intermediate-tight epithelial cell line, MDCK C7 and HT-29/B6, were stably transfected with CRISPR/Cas9 and single-guide RNA targeting angulin-1 and morphologically and functionally characterized. Water flux induced by an osmotic gradient using 4-kDa dextran caused water flux to increase in angulin-1 KO clones in MDCK C7 cells, but not in HT-29/B6 cells. In addition, we found that water permeability in HT-29/B6 cells was not modified after either angulin-1 knockout or tricellulin knockdown, which may be related to the presence of other pathways, which reduce the impact of the tTJ pathway. In conclusion, modulation of the tTJ by knockout or knockdown of tTJ proteins affects ion and macromolecule permeability in tight and intermediate-tight epithelial cell lines, while the transepithelial water permeability was affected only in tight cell lines.     

Host Mesothelin Expression Increases Ovarian Cancer Metastasis in the Peritoneal Microenvironment

Mesothelin (MSLN), a glycoprotein normally expressed by mesothelial cells, is overexpressed in ovarian cancer (OvCa) suggesting a role in tumor progression, although the biological function is not fully understood. OvCa has a high mortality rate due to diagnosis at advanced stage disease with intraperitoneal metastasis. Tumor cells detach from the primary tumor as single cells or multicellular aggregates (MCAs) and attach to the mesothelium of organs within the peritoneal cavity producing widely disseminated secondary lesions. To investigate the role of host MSLN in the peritoneal cavity we used a mouse model with a null mutation in the MSLN gene (MSLN^KO). The deletion of host MSLN expression modified the peritoneal ultrastructure resulting in abnormal mesothelial cell surface architecture and altered omental collagen fibril organization. Co-culture of murine OvCa cells with primary mesothelial cells regardless of MSLN expression formed compact MCAs. However, co-culture with MSLN^KO mesothelial cells resulted in smaller MCAs. An allograft tumor study, using wild-type mice (MSLN^WT) or MSLN^KO mice injected intraperitoneally with murine OvCa cells demonstrated a significant decrease in peritoneal metastatic tumor burden in MSLN^KO mice compared to MSLN^WT mice. Together, these data support a role for host MSLN in the progression of OvCa metastasis.     

A Novel Formulation of Glucose-Sparing Peritoneal Dialysis Solutions with l-Carnitine Improves Biocompatibility on Human Mesothelial Cells

The main reason why peritoneal dialysis (PD) still has limited use in the management of patients with end-stage renal disease (ESRD) lies in the fact that the currently used glucose-based PD solutions are not completely biocompatible and determine, over time, the degeneration of the peritoneal membrane (PM) and consequent loss of ultrafiltration (UF). Here we evaluated the biocompatibility of a novel formulation of dialytic solutions, in which a substantial amount of glucose is replaced by two osmometabolic agents, xylitol and l-carnitine. The effect of this novel formulation on cell viability, the integrity of the mesothelial barrier and secretion of pro-inflammatory cytokines was evaluated on human mesothelial cells grown on cell culture inserts and exposed to the PD solution only at the apical side, mimicking the condition of a PD dwell. The results were compared to those obtained after exposure to a panel of dialytic solutions commonly used in clinical practice. We report here compelling evidence that this novel formulation shows better performance in terms of higher cell viability, better preservation of the integrity of the mesothelial layer and reduced release of pro-inflammatory cytokines. This new formulation could represent a step forward towards obtaining PD solutions with high biocompatibility.     

Counterion motions and thermal ordering effects in perfluorosulfonate ionomers probed by solid-state NMR

Perfluorosulfonate ionomers (PFSIs) neutralized by tetraalkylammonium ions have been investigated using variable temperature ¹H and ¹³C solid-state NMR (ssNMR) spectroscopy to probe the thermally induced properties of tetraalkylammonium ions at temperatures near the α-relaxations. Tetramethylammonium (TMA⁺), tetraethylammonium (TEA⁺), tetrapropylammonium (TPA⁺) and tetrabutylammonium (TBA⁺) ions have been incorporated in our study for the systematic control of ionic interactions within PFSIs according to the chain-length of ammonium ions. ¹³C static ssNMR results show that bulkier TPA⁺ and TBA⁺ ions undergo molecular tumbling motions near or above the α-relaxation temperature of the corresponding PFSI ionomers, with jumping rates of κ ≈ 1 kHz. Moreover, the results of ¹H spin-lattice (T₁) relaxation time measurements suggest that smaller TMA⁺ ions in the PFSI exhibit a thermally induced ordering effect as the sample temperature approaches the α-relaxation temperature of TMA⁺-PFSI. This ordering phenomenon is also supported by the results from small-angle X-ray scattering.     

质子传导膜内受限空间离子扩散过程

以具有纳米尺度孔径的聚偏氟乙烯(PVDF)质子传导膜为对象,研究电解质溶液中水合离子在受限空间内的传递行为,证明使用纳米尺度多孔膜代替离子交换膜用于液流电池过程的可行性。利用渗透实验分别研究浓度场、压力场,以及不同渗透压条件下膜中离子扩散和水迁移现象,分析传质行为与膜结构和组成之间的关系。结果表明离子在纳米尺度孔径的PVDF膜中的扩散过程与溶液中类似,表观离子扩散系数不受浓度差推动力的影响;离子交换膜中的表观离子扩散系数随浓度差推动力提高而增加。在渗透压作用下,自制PVDF纳米孔膜的水迁移速率低于Nafion 117膜,水迁移带来的负面影响更小;对于H⁺/VO²⁺的离子选择系数超过300,有效透过H⁺而阻止VO²⁺,适用于全钒液流电池过程。     

Liquid Membrane Separations of Metal Cations Using Macrocyclic Carriers

Abstract

The selectivity in water and methanol solvents of macrocyclic crown ether ligands toward univalent and bivalent cations is well known. Incorporation of these ligands into chloroform liquid membranes separating water and salt solution phases results in a system showing selective cation transport. The cation transport rates of single cations across these liquid membranes have been correlated with equilibrium constant values for cation-macrocycle interaction in methanol. This correlation has been extended to binary cation mixtures of Cs⁺ with Li⁺, Na⁺, K⁺, and Rb⁺. A model for cation transport from these cation mixtures has been reduced to an equation which gives good agreement between measured and predicted transport rates across our liquid membranes.