Presence Of Membrane Research Articles

Correlation between Computed Ion Hydration Properties and Experimental Values of Sugar Transfer through Nanofiltration and Ion Exchange Membranes in Presence of Electrolyte

The widespread use of nanofiltration and electrodialysis membrane processes is slowed down by the difficulties in predicting the membrane performances for treating streams of variable ionic compositions. Correlations between ion hydration properties and solute transfer can help to overcome this drawback. This research aims to investigate the correlation between theoretically evaluated hydration properties of major ions in solution and experimental values of neutral organic solute fluxes. In particular, ion hydration energies, coordination and hydration number and the average ion-water distance of Na+, Ca2+, Mg2+, Cl− and SO42− were calculated at a high quantum mechanics level and compared with experimental sugar fluxes previously reported. The properties computed by simple and not computationally expensive models were validated with information from the literature. This work discusses the correlation between the hydration energies of ions and fluxes of three saccharides, measured through nanofiltration and ionic-exchange membranes. In nanofiltration, the sugar flux increases with the presence of ions of increasing hydration energy. Instead, inverse linear correlations were found between the hydration energy and the sugar fluxes through ion exchange membranes. Finally, an empirical model is proposed for a rough evaluation of the variation in sugar fluxes as function of hydration energy for the ion exchange membranes in diffusion experiments.

Polyaniline Composite Membranes Synthesis in Presence of Various Acid Dopants for Pressure Filtration

Polyaniline is a conductive polymer that is recently used as a material in producing a pressure filtration membrane. Polyaniline can be doped in various acids as dopants of different sizes and shapes to modify its inherent properties to produce membrane with high flux and rejection. This work is aimed to fabricate polyaniline composite membrane in presence of different acids as dopants namely hydrochloric acid, maleic acid, poly(methyl vinylether) acid (PMVEA) and polyacrylic acid (PAA). This polyaniline was coated onto microporous polyvinylidene fluoride (PVDF) support by using a specially fabricated two compartment cell. The field emission scanning electron microscope (FESEM) results show that the morphology of the coated polyaniline on PVDF membrane support is in globular shapes, which elongates at different sizes depending to the acid used. From the thermal analysis, the melting point of polyaniline coated PVDF membrane remains at 260°C, similar as obtained in the pristine microporous PVDF indicating no thermal change upon polyaniline coating. From all membranes prepared, the doped polyaniline membrane possessed a good conductivity value except for polyaniline-PMVEA membrane, which has the lowest value. In terms of the membrane filtration performance, which was measured based on the flux of pure water and polyethylene glycol (PEG) rejection, polyaniline-PMVEA membrane has a high flux and the highest PEG rejection. This result indicates that the conductivity does not influence much on the membrane filtration performance, but rather due to the physical coating itself. Different acid dopants present during polyaniline coating will lead to different filtration performance.

Exploring CO2 capture from pressurized industrial gaseous effluents in membrane contactor-based pilot plant

In recent years microporous hollow fiber membrane contactors (HFMCs) have been intensively studied for many separation operations, among which chemical CO2 absorption from gaseous mixtures. The vast majority of studies on this subject are conducted at laboratory scale and focus on simple model gases. At pilot and demonstration scale fewer investigations are available and a thorough knowledge on the concrete applicability of HFMCs under realistic conditions is still lacking at present.This work stems from a cooperative project involving two industrial partners, IPLOM, a refinery, and Italiana Coke, a coking plant, strongly interested in a possible implementation of HFMC-based units within their processes. A pilot plant has been expressly designed and operated for this study; the heart is a special pressure-resistant HFMC. Our aim was to experimentally assess the behavior of membranes in presence of raw industrial gaseous effluents which, due to their own complexity, could generate unexpected and challenging problems. At the same time different absorbing aqueous solutions, giving rise to different membrane/solvent interactions, have been assessed. Particular efforts were devoted in this work to exploring the feasibility of HFMC-based devices capable of operating at elevated pressures, an important issue on which a surprising lack of information exists.

Molecular dynamics simulation and Monte Carlo study of transport and structural properties of PEBA 1657 and 2533 membranes modified by functionalized POSS-PEG material

In this study, structural and transport mechanism and properties of two kinds of polyether block amide (PEBA 1657, PEBA 2533) membrane in presence of POSS-PEG functionalized nanoparticles were investigated by molecular dynamic simulation (MD). Monte Carlo technique was used to investigate transport properties of the simulated membranes. The wide-angle XRD (WAXD), mean square displacement (MSD), glass transition temperature (Tg) and sorption isotherm were studied to investigate the aforementioned mixed matrix membranes. Also, solubility, diffusivity, permeability and permselectivity of light gases (N2, CO2, CH4, O2, and H2) were investigated carefully by Materials Studio simulator. The results showed higher permeability for membranes with PEBA 2533 rather than the ones with PEBA 1657; this conclusion is also confirmed with the experimental results which are reported in the literature. But, for the permselectivity of membranes, the results were opposite of the permeability results. Tg for all membranes decreased by increasing the POSS-PEG nanoparticle content. Additionally, by comparing the results of the simulations with the results of literature, it is revealed that simulation results were in acceptable agreement by experiment results.

Structure and phase transitions of the multilamellar DMPC membranes in presence of the DMSO and DESO

The structure and phase transitions of the prepared and formed spontaneously multilamellar vesicles (MLVs) of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) in dimethyl sulfoxide (DMSO) and diethyl sulfoxide (DESO) were investigated using small angle neutron scattering (SANS). The both polar aprotic solvents increase the temperature of the main phase transition (Tm). The pre-transition does not observed at sulfoxides mole fraction X = 0.2. The transition of the MLVs DMPC in the presence DMSO from gel to liquid-crystalline phase occurs at lower temperature. The method of the MLVs preparation has directly effects on the temperature of the main phase transition and its structure. The value of Tm is higher with ∼ 4.6 ºC in case of the spontaneous forming MLVs from extruded ULVs. The thickness of the solvent layer for prepared MLVs is less by 4.0 Å in gel phase and by 5.6 Å in liquid-crystalline phase than the thickness of the solvent layer for spontaneously formed MLVs.

Association of the polymorphism 12109g>A from the REN gene as a risk factor for preterm birth.

Introduction:Preterm birth is the most important cause of neonatal mortality and morbidity. It is a multifactorial disease with different etiologies, including genetic factors. Genetic variability is represented by single nucleotide polymorphisms (SNPs) in genes of proteins involved in the contractile activity. We determine the association between SNP 12109G> A in REN associated with preterm birth and premature rupture of membrane.Materials and methods:A study of cases (N=112, 22–36 weeks of gestation; mean: 31, 95% confidence interval 30.7–32.2) and controls (N=66; 38–40 weeks of gestation from the last menstrual period; mean: 39.8, 95% confidence interval 38.9–39.4) was performed. Genomic DNA was isolated in all patients from peripheral blood. The SNP 12109G> A (Mbo I) in REN was typified by PCR-restriction fragment length polymorphism.Results:A significant difference in the case group for the SNP 12109G>A was observed. The A allele was increased in women with preterm birth (81% cases vs. 15% control, p<0.0000004). There was also a significant difference between genotypes, mainly an excess of G/A heterozygotes in women with preterm birth (60% cases vs. 23% controls). The phenotype 12109G> A has odds ratio 6.62 (95% confidence interval 3.14–14.15), which means a high risk of preterm birth/premature rupture of membrane in presence of allele A, both in homozygotes and in heterozygotes.Conclusion:Allelic frequency of A of SNP 12109G>A was higher in women with preterm birth than in women with normal vaginal delivery and could be considered a risk factor.

Chronopotentiometric study of a Nafion membrane in presence of glucose

Chronopotentiometric and swelling experiments have been conducted to characterize the behavior of a Nafion membrane in NaCl and KCl aqueous solutions without and with glucose. A mixture solution with similar composition to the cerebrospinal fluid and blood plasma has also been studied. From the chronotentiograms, current-voltage curves have been obtained, and the values of the limiting current density, diffusion boundary layer thickness, difference between counter-ion transport number in membrane and free solution, and transition times have been determined for the investigated membrane systems. The obtained results indicate that the presence of glucose affects the ion transport through the membrane depending on the electrolyte and glucose concentrations. At low electrolyte concentration, experimental transition times are found to be smaller in presence of glucose, which has been related to an effective membrane area reduction in presence of glucose. The membrane system corresponding to the mixture solution shows a behavior similar to the single high concentration NaCl membrane system, indicating that the observed behavior is mainly associated to the Na+ ions transport in higher proportion. In this case, the glucose presence does not affect significantly the investigated properties of the membrane, which is interesting for its utilization in a glucose fuel cell.

Physical, Mechanical and Antimicrobial Evaluations of Physically Crosslinked PVA/Chitosan Hydrogels Containing Nanoparticles

Chitosan / montmorillonite (MMT) and Poly vinyl Alcohol (PVA) / Silver nanoparticles (AgNPs) nanocomposites were prepared and formed hydrogel membranes using freeze thawing technique. The properties of the prepared hydrogels were investigated and compared to hydrogel membranes in presence and absence of nanometals. The physical behavior, mechanical properties and antibacterial activity was examined. Also the surface morphology monitored using scanning electron microscope. Antimicrobial activity against bacteria and yeast was also examined. The obtained results showed positive effect of nanometals especially AgNPs on swelling percent on the other hand tensile strength were combined by presence of MMT nanoparticles. The surface morphology showed homogenous images for all samples except samples containing MMT. All prepared samples containing nanoparticles showed antibacterial activity especially hydrogel membranes containing AgNPs.

Colloidal fouling of nanofiltration membranes: A novel transient electrokinetic model and experimental study

Fouling of nanofiltration (NF) membranes by colloidal matter is a commonly encountered phenomenon, adversely influencing the permeate quality and membrane life. In this work, a transient electrokinetic model has been developed to predict the permeate flux and observed rejection of NF membranes in presence of colloidal particles. The cake layer is considered as a swarm of non-interacting, incompressible, spherical, charged particles and the structure is represented using the cell model approach. In the cell model a single particle and a representative volume of the fluid enclosing that particle is considered. The hydrodynamic drag exerted by the stationary colloidal cake layer is obtained by the Stokes–Einstein law and combined with Kuwabara cell model to account for the effect of neighboring particles. The transport of solvent around the charged particles distorts the ionic distribution causing the development of streaming potential and electroosmotic back flow. The model provides valuable insight into application of this phenomenon in colloidal fouling of membranes, in light of the classical Levine–Neale cell model of electrophoresis. This model is then coupled with film theory to appraise the permeate flux decline and salt rejection during the filtration processes. To validate the model, cross flow NF experiment was conducted with silica particles and sodium chloride solution over a wide range of operating conditions.

Transport Studies of Monovalent Ions through Nafion-117 Ion Exchange Membrane in Presence of Polyacrylate

The results of equilibrium distribution and transport kinetics of monovalent (Li+, Na+, and Cs+) ions through Nafion-117 ion exchange membrane in presence of polyacrylate anion have been presented. For Na+-Li+ system, equilibrium distributions in the presence and absence of polyacrylate have been found to be the same indicating that the Donnan membrane equilibrium is not affected by the presence of polyacrylate. For the Na+-Cs+ system, a favored transport of Cs+ ion to the polyacrylate compartment has been observed, indicating the binding of Cs+ ion with polyacrylate is stronger than other monovalent ions. This is due to the lower hydration radius of Cs+ ions. The deviation from Donnan membrane equilibrium condition has been used to obtain information about the fraction of counter-ions bound to the polyacrylate. The transport profile in the presence of polyacrylate has also been calculated based on the modified Nernst Planck (NP) approach, taking into account the fraction of counter-ions bound to the polyacrylate ion. The Donnan relation has been used to obtain the concentration of ions at the solution/membrane interface. The self-diffusion coefficients of ions and membrane ion exchange capacity have been given as input parameters in the calculations. The calculated time profile has been found to agree well with the experimental time profile.

Analysis of H2S Tolerance of Pd-Cu Alloy Hydrogen Separation Membranes

The presence of a limited amount of H2S in H2-rich feed adversely affects the Pd-Cu membrane permeation performance due to the sulphidization of the membrane surface. A theoretical model was proposed to predict the S-tolerant performance of the Pd-Cu membranes in presence of H2S under the industrial water-gas-shift (WGS) reaction conditions. The ideas of surface coverage and competitive adsorption thermodynamics of H2S and H2 on Pd-Cu surface were introduced in the model. The surface sulphidization of the Pd-Cu membranes mainly depended on the pressure ratio of H2S to H2, temperature and S-adsorbed surface coverage, i.e., the occurrence of sulphidization on the surface was not directly related with the bulk compositions and structures [body centered cubic and face centered cubic (bcc or fcc)] of Pd-Cu alloy membranes because of the surface segregation phenomena. The resulting equilibrium equations for the H2S adsorption/sulphidization reactions were solved to calculate the pressure ratio of H2S to H2 over a wide range of temperatures. A validation of the model was performed through a comparison between lots of literature data and the model calculations over a rather broad range of operating conditions. An extremely good agreement was obtained in the different cases, and thus, the model can serve to guide the development of S-resistant Pd alloy membrane materials for hydrogen separation.

Oily Water Treatment Using Ceramic Membrane in Presence of Swirling Flow Induced by a Tangential Inlet via CFD

In recent years, attention has been given to the processes controlling the emission of oily effluents and their environmental impact. Many industrial processes generate large volumes of water contaminated with oil, called oily waters. The oily water must be treated before its discard in order to meet the criteria established by environmental agencies (for example in Brazil, 20 mg/L). In present days, the process of separating oil/water with ceramic membranes has attracted the attention of many researchers [1,2]. In this sense, the aim of this study is to evaluate the influence of the tangential inlet shape in the oil/water separation via ceramic membranes. We use a mathematical multiphase flow model to describe the oil-water separation, based on the particle model. Here oil is the dispersed phase while water the continuous phase. To model the turbulence effect we use the RNG k-ε model. All simulations were carried out using the Ansys CFX ® commercial code. Results of streamlines and velocity, pressure and volume fraction of phase fields are present and analyzed. The numerical results indicate that no significant difference when using a circular or rectangular pipe with the same cross-sectional area.

Energetic consideration and flux characteristics of roughed-surface membrane in presence of reversing shear

Flux characteristics and energy dissipation for oscillatory flat surface membranes roughed with turbulence promoters (TP) have been investigated both theoretically and experimentally. The combined effect of oscillations and TP has proven effective in enhancing the microfiltration flux by an almost order of magnitude over that for a non-oscillatory flat surface membranes, and close to four times higher than that achieved in the absence of TP under the same oscillation conditions. The power dissipation was determined using the drag and inertia forces acting on individual promoters, as well from the solution of the boundary layer equations with time-invariant eddy viscosity for large and small roughness conditions. Using higher oscillation frequency and lower amplitudes was found to be more effective for flux enhancement and energy utilization where near self cleaning conditions were achieved at specific energy consumption of less than ∼0.5kWh/m3 filtrate. Both grooved and flat TP gave similar results in terms of flux enhancement and energy consumption per unit filtrate, with the former slightly better. Membrane fouling was found to follow the intermediate blocking fouling mechanism for oscillatory membranes as compared to cake filtration for non-oscillating systems. The quasi-steady state flux was satisfactorily predicted using an analytical model based on oscillatory rough surfaces with R2=0.95.

A voltage-gated pore for translocation of tRNA

Very little is known about how nucleic acids are translocated across membranes. The multi-subunit RNA Import Complex (RIC) from mitochondria of the kinetoplastid protozoon Leishmania tropica induces translocation of tRNAs across artificial or natural membranes, but the nature of the translocation pore remains unknown. We show that subunits RIC6 and RIC9 assemble on the membrane in presence of subunit RIC4A to form complex R3. Atomic Force Microscopy of R3 revealed particles with an asymmetric surface groove of ∼20nm rim diameter and ∼1nm depth. R3 induced translocation of tRNA into liposomes when the pH of the medium was lowered to ∼6 in the absence of ATP. R3-mediated tRNA translocation could also be induced at neutral pH by a K+ diffusion potential with an optimum of 60–70mV. Point mutations in the Cys2–His2 Fe-binding motif of RIC6, which is homologous to the respiratory Complex III Fe–S protein, abrogated import induced by low pH but not by K+ diffusion potential. These results indicate that the R3 complex forms a pore that is gated by a proton-generated membrane potential and that the Fe–S binding region of RIC6 has a role in proton translocation. The tRNA import complex of L. tropica thus contains a novel macromolecular channel distinct from the mitochondrial protein import pore that is apparently involved in tRNA import in some species.

Molecular Dynamics Simulation of a Pure Lipid Membrane in Presence of Polar and Non Polar Drugs

Anesthetics, in general, are a big discussion topic when it comes to describe their way of action. There are two main models that portray such process. The first and more accepted one states a direct effect over the proteins receptors of the membrane that regulates the nervous impulse. The second gives more emphasis on the membrane lipids, in which more tangible properties are taken in consideration, such as its compressibility. This model poses a more general and less specific way of action that the one suggested by the membrane protein receptors.In our work, we study the electrostatic properties of the interaction of a drug and a membrane model by solving the Poisson-Boltzmann equation. Moreover, we also simulate the dynamics of the system by Molecular Dynamics (MD). As a final approach we estimate the configurational entropy in order to understand how the system behaves and evolves in time.We build five systems whose main component is a bilayer membrane of the saturated lipid Dipalmitoylphosphatidylcholine (DPPC), in presence of four different drugs: caffeine, lidocaine, procaine and tetracaine. One for each molecule and a fifth as a control.From the positions and energies results of the MD, it was possible to see how the caffeine posses a certain preference for the polar region of the membrane model and the anesthetics for the apolar region. These last ones produced a destabilization effect over the lipid tails of the membrane, which we were able to measured by means of a configurational entropy. Each molecule, lidocaine, procaine and tetracaine, gave increasing values of entropy; this is a direct effect of the membrane disorganization, offering a possible explanation on how different anesthetics provide such different effectiveness.

Cultivating oral mucosa epithelial transplantation (COMET) followed by penetrating keratoplasty (PK) in ocular surface reconstruction

AbstractPurpose Efficacy of COMET and subsequent PK in patients with limbal insufficiency combined with stromal corneal haze after corneal burnsMethods 15 patients (16 eyes)who underwent corneal burns with vascular conjuctival pannus and stromal involvement underwent autologous cultivated oral mucosa epithelial transplantation. Cellular material was obtained from buccal mucosa, tripsinized, and settled on the previously prepared culture dishes. Cultures was carried on denuded amniotic membrane in presence of inactivated with mitomycin C 3T3 fibroblasts. At least 12 month after epithelium restoration patients underwent PK. Corneal surface stability and visual acuity were evaluated.Results 6 month after last step of the surgery 68,7% of eyes had transparent cornea without reccurent revascularization, 31,2 % of eyes developed vascular pannus again with vascular ingrowth on the transplanted cornea ( in 2 cases visual axis was involved), in 62,5 % of eyes visual acuity increased from mean 0,01 to 0,3.Conclusion COMET combined with PK effectively improves ocular surface stability and quality of vision.

Influence of the support on permeation of palladium composite membranes in presence of sweep gas

The influence of the porous support on hydrogen permeation of a Pd-composite membrane in presence of sweep gas has been evaluated. A 20μm thick palladium membrane has been prepared by electroless plating on a tubular stainless steel support. H2 permeation tests have been performed in a laboratory pilot loop up to 400°C and 800kPa; a nitrogen sweep gas in the 0–100Nl/h flow rate range has been fed to the permeate side. H2 flux through the Pd-membrane has been first measured in absence of sweep gas. Permeation can be described by the Sieverts’ law and the best fitting of the pressure exponent (n-value) at 400°C is 0.67. Support resistance, estimated by using dusty-gas model equation, determines an increase of H2 pressure at the interface between Pd-layer and support from 100 to 140kPa, and a H2 flux reduction of the 9.8%, approximately. While feeding N2 as a sweep gas, a H2 flux much lower than expected by considering Sieverts’ law is measured. The difference between experimental results and expected values, calculated by a simple uni-dimensional model is about the 30%, at the higher flow rates. Moreover the increase of n-value from 0.68 up to 0.9 suggests a strong increase in the mass transfer resistance of the support. The resistance to H2 diffusion due to presence of stagnant N2 in the support pores has been then estimated by using the dusty gas model equation, which combines Knudsen diffusion, viscous flow and binary diffusion. Results indicate that binary diffusion of H2 in stagnant N2 can be responsible of the observed H2 flux reduction. H2 partial pressure calculated at the interface between Pd-layer and support in presence of sweep gas is always significantly higher than H2 partial pressure measured in the permeate. This difference is progressively increasing while increasing sweep gas flow rate and tends to saturate at high flow rates.

Selective Interactions of Valeriana officinalis Extracts and Valerenic Acid with [3H]Glutamate Binding to Rat Synaptic Membranes

Although GABA neurotransmission has been suggested as a mechanism for Valeriana officinalis effects, CNS depression can also be evoked by inhibition of ionotropic (iGluR) and metabotropic glutamate receptors (mGluR). In this study, we examined if aqueous valerian extract interacted with glutamatergic receptors. Freshly prepared aqueous valerian extract was incubated with rat cortical synaptic membranes in presence of 20 nM [3H]Glutamate. Aqueous valerian extract increased [3H]Glutamate binding from 1 × 10−7 to 1 × 10−3 mg/mL. In the presence of (2S,1′S,2′S)-2-(Carboxycyclopropyl)glycine (LCCG-I) and (2S,2′R,3′R)-2-(2′,3′-Dicarboxycyclopropyl)glycine (DCG-IV), Group II mGluR agents, valerian extract markedly decreased [3H]Glutamate binding, while (2S)-2-amino-3-(3,5-dioxo-1,2,4-oxadiazolidin-2-yl) propanoic acid) (quisqualic acid, QA), Group I mGluR agonist, increased [3H]Glutamate binding. At 0.05 mg/mL aqueous valerian extract specifically interacted with kainic acid NMDA and AMPA receptors. Valerenic acid, a marker compound for Valeriana officinalis, increased the [3H]Glutamate binding after 1.6 × 10−2 mg/mL, and at 0.008 mg/mL it interacted only with QA (Group I mGluR). The selective interactions of valerian extract and valerenic acid with Group I and Group II mGluR may represent an alternative explanation for the anxiolytic properties of this plant.

Altered placental glutathione peroxidase mRNA expression in preeclampsia according to the presence or absence of labor

Increased placental oxidative stress in preeclampsia (PE) has been associated in part to a decrease in glutathione peroxidase (GPX) antioxidant activity. However, it is not clear if GPX mRNA expression is affected in PE, and how the presence of labor may impair this expression. In this study, we characterized by quantitative PCR, in situ hybridization and immunohistochemistry, the expression of four GPX (GPX1 to 4) in the placenta of normotensive (NP; n = 23) and PE pregnancies (n = 25) according to mode of delivery: vaginal delivery (with labor) or cesarean (without labor); the tissue layer: amnion-chorion (AC) and villi; and the sampling site: peri-insertion or peripheral. Concomitantly, oxidative stress markers mRNA expression, HSP70 and HO-1 were measured. All GPX mRNA and protein were detected in all layers of the placenta and sampling sites. In absence of labor, GPX1 is more expressed near the umbilical cord than at the periphery of the villi (p = 0.037). At the periphery of AC membranes, GPX2 was more expressed in PE than in controls in presence of labor (p = 0.037). Interestingly, GPX4 mRNA level was clearly deficient in the PE villi in presence or absence of labor (p < 0.0473). Also, the GPX4 expression in PE was lower than controls in AC membranes in presence of labor (p = 0.0007). Oxidative stress markers, HSP70 and HO-1, were higher in PE placental membranes than in controls in absence of labor (p < 0.011). HSP70 was also upregulated in PE placental membranes in presence of labor (p = 0.034). Correlations between stress markers and GPX mRNA expression were mostly present in AC membranes in presence of labor in NP. Most of the latter correlations were lost in PE. In conclusion, our results suggest that the reported decrease in GPx activity and increased oxidative stress in PE placental villi may be attributed in part to GPX4 independently of the presence or absence of labor.

Aqueous and Ethanolic Valeriana officinalis Extracts Change the Binding of Ligands to Glutamate Receptors

The effects of two valerian extracts (aqueous and hydroalcoholic) were investigated through [3H]Glutamate ([3H]Glu) and [3H]Fluorowillardine ([3H]FW) receptor binding assays using rat synaptic membranes in presence of different receptor ligands. In addition, the extract stability was monitored spectrophotometrically. Both extracts demonstrated interaction with ionotropic glutamate receptors (iGluRs). However, the extracts displayed considerable differences in receptor selectivity. The hydroalcoholic extract selectively interacted with quisqualic acid (QA), group I metabotropic glutamate receptor (mGluR) ligand, while the aqueous extract did not alter the binding of QA. The stability of the extracts was examined during several weeks. Freshly prepared extract inhibited 38–60% of [3H]FW binding (AMPA). After 10 days, the aqueous extract inhibited 85% of [3H]FW binding while the hydroalcoholic extract markedly potentiated (200%) [3H]FW binding to AMPA receptors. Thus, our results showed that factors such as extraction solvent and extract stability determine the selectivity for glutamate receptor (GluR) interactions.