New Membrane-Forming Aromatic Co-Poly(amide-imide)s: Influence of the Chemical Structure on the Morphological, Thermal and Transport Properties

Polymer film membranes are used to solve specific separation problems that dictate structural requirements. Structural and morphological parameters of film membranes based on glassy polyheteroarylenes can be controlled in the process of preparation from solutions that opens up prospects for obtaining structured membranes required for targeted separation. In the case of aromatic poly(amide-imide)s, the possibility of controlling film formation and structure virtually has not been studied. In the present work, a series of homologous co-poly(amide-imide)s differing in the number of repeating units with carboxyl-substituted aromatic fragments was synthesized by polycondensation. Comparative analysis of the processes of formation of membranes with different morphologies based on these polymers under equal conditions was performed. New information was obtained about the influence of the amounts of carboxyl groups and the residual solvent on structural properties of asymmetric membranes. The influence of these factors on transport properties of dense membranes under pervaporation conditions was studied. It was demonstrated that in the case of carboxyl-containing poly(amide-imide)s, the domains formed during film preparation had a significant effect on membrane properties.

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Gas transport through integral-asymmetric membranes: A comparison to isotropic film transport properties

Journal of Applied Polymer Science ◽

10.1002/app.1993.070481210 ◽

1993 ◽

Vol 48 (12) ◽

pp. 2161-2171 ◽

Cited By ~ 50

Author(s):

P. H. Pfromm ◽

I. Pinnau ◽

W. J. Koros

Keyword(s):

Transport Properties ◽

Gas Transport ◽

Asymmetric Membranes

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Structural Analysis of Fucoidans

Natural Product Communications ◽

10.1177/1934578x0800301011 ◽

2008 ◽

Vol 3 (10) ◽

pp. 1934578X0800301 ◽

Cited By ~ 13

Author(s):

Maria I. Bilan ◽

Anatolii I. Usov

Keyword(s):

Biological Activity ◽

Structural Analysis ◽

Charge Density ◽

Brown Algae ◽

Uronic Acid ◽

Chemical Structure ◽

Biological Activities ◽

Biological Properties ◽

Sulfated Polysaccharides ◽

New Information

Sulfated polysaccharides of brown algae (“fucoidans”) constitute a wide variety of biopolymers from simple sulfated fucans up to complex heteropolysaccharides composed of several neutral monosaccharides, uronic acid and sulfate. The increased interest in this class of polysaccharides is explained by their high and versatile biological activities, and hence, by their possible use in new drug design. Structural analysis of several fucoidans demonstrates that their biological properties are determined not only by charge density, but also by fine chemical structure, although distinct correlations between structure and biological activity cannot be formulated at present. The aim of this review is to describe the methods of structural analysis currently used in fucoidan chemistry, and to discuss some new information on the structures of fucoidans presented in recent publications.

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Alkali Attack on Cation-Exchange Membranes with Polyvinyl Chloride Backing and Binder: Comparison with Anion-Exchange Membranes

Membranes ◽

10.3390/membranes10090228 ◽

2020 ◽

Vol 10 (9) ◽

pp. 228 ◽

Cited By ~ 1

Author(s):

Shoichi Doi ◽

Nobuya Takumi ◽

Yuriko Kakihana ◽

Mitsuru Higa

Keyword(s):

Cation Exchange ◽

Anion Exchange ◽

Polyvinyl Chloride ◽

Chemical Structure ◽

Immersion Test ◽

Ion Concentration ◽

Membrane Properties ◽

Anion Exchange Membranes ◽

Alkali Solutions ◽

Exchange Membrane

Systematic alkali immersion tests of cation-exchange membranes (CEM) with polyvinyl chloride (PVC) as their backing and binder were conducted to compare that of an Anion-exchange membrane (AEM) with the same PVC materials to investigate the mechanism of dehydrochlorination. In the immersion tests, originally colorless and transparent AEM turned violet, and chemical structure analysis showed that polyene was produced by the dehydrochlorination reaction. However, the CEM did not change in color, chemical structure or membrane properties during the test with less than 1M alkali solutions. According to the Donnan equilibrium theory and the experiments using CEM and AEM, the hydroxide ion concentration in the CEM was much lower than that in the AEM under the same conditions. However, when the alkali immersion test was performed using the CEM under more severe conditions (6 M for 168 h at 40 °C), there was a slight change in the color and chemical structure of the CEM, clearly indicating that not only AEMs, but also CEMs with PVC matrixes were deteriorated by alkali, depending on the conditions.

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Poly(o-aminophenol) film electrodes: synthesis and characterization and formation mechanisms — A review article

Canadian Journal of Chemistry ◽

10.1139/cjc-2012-0031 ◽

2013 ◽

Vol 91 (2) ◽

pp. 91-112 ◽

Cited By ~ 12

Author(s):

R. Tucceri ◽

P.M. Arnal ◽

A.N. Scian

Keyword(s):

Chemical Structure ◽

Electrode Materials ◽

Film Formation ◽

Protective Layer ◽

Spectroscopic Characterization ◽

Spectroscopic Studies ◽

Formation Mechanisms ◽

Neutral Media ◽

Electro Oxidation ◽

Basic Solutions

This review, which is divided into three parts, concerns electrochemical synthesis, spectroscopic characterization, and formation mechanisms of poly(o-aminophenol) (POAP) film electrodes. The first part of this review is devoted to describing the electropolymerization process of o-aminophenol (o-AP) on different electrode materials and in different electrolyte media by employing both potentiodynamic and potentiostatic methods. The evolution of the voltammogram during the electrosynthesis of POAP and the assignation of the voltammetric peaks to different species, according to the formation mechanism formulated by each author, are described. The effects of some chemical substances and electrochemical pretreatments of the electrode surface, on the electropolymerization process of o-AP, are also considered in this part of the review. The synthesis of POAP in neutral media, which yields a nonconducting polymer, and its use as component of biosensors and protective layer in corrosion processes, are analyzed at the end of the first part. The second part of this review refers to spectroscopic studies carried out by different authors to both identify the products of the o-AP electro-oxidation and elucidate the chemical structure of POAP film electrodes. This second part of the review also describes the different spectroscopic methods employed to study the redox process of POAP, which allows the demonstration of the existence of transient species during the transition of the completely oxidized form of POAP to the completely reduced one. The third part of this review shows the different mechanisms formulated to interpret the POAP film formation from both acid and basic solutions of o-AP. Also, some electrochemical and spectroscopic data which allowed to propos the corresponding formation mechanisms, especially in basic media, are described.

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Effect of Temperature on the Transport Properties and Morphology of Polymeric Asymmetric Membranes

Separation Science and Technology ◽

10.1080/01496399708003212 ◽

1997 ◽

Vol 32 (1-4) ◽

pp. 505-525 ◽

Cited By ~ 4

Author(s):

Mary E. Rezac ◽

N. Shanan Moore ◽

Alan Back

Keyword(s):

Transport Properties ◽

Effect Of Temperature ◽

Asymmetric Membranes

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Preferential (100)-oriented CH3NH3PbI3 perovskite film formation by flash drying and elucidation of formation mechanism

RSC Advances ◽

10.1039/c6ra21423a ◽

2016 ◽

Vol 6 (97) ◽

pp. 94502-94509 ◽

Cited By ~ 3

Author(s):

Se-Yun Kim ◽

Hyo-Jeong Jo ◽

Shi-Joon Sung ◽

Kang-Pil Kim ◽

Young-Woo Heo ◽

...

Keyword(s):

Formation Mechanism ◽

Thermal Energy ◽

Spin Coating ◽

Film Formation ◽

Residual Solvent ◽

Growth Properties ◽

Flash Drying

It was found that the amount of thermal energy delivered during annealing and the amount of residual solvent remaining after spin coating play critical roles in determining the growth properties of (100)-oriented perovskite films.

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Observable effects of Ca 2+ buffers on local Ca 2+ signals

Philosophical Transactions of The Royal Society A Mathematical Physical and Engineering Sciences ◽

10.1098/rsta.2010.0273 ◽

2010 ◽

Vol 368 (1933) ◽

pp. 5597-5603 ◽

Cited By ~ 4

Author(s):

Guillermo Solovey ◽

Silvina Ponce Dawson

Keyword(s):

High Resolution ◽

Transport Properties ◽

Calcium Entry ◽

Calcium Signals ◽

Physiological Processes ◽

New Information ◽

Inositol 1,4,5 Trisphosphate

Calcium signals participate in a large variety of physiological processes. In many instances, they involve calcium entry through inositol 1,4,5-trisphosphate (IP 3 ) receptors (IP 3 Rs), which are usually organized in clusters. Recent high-resolution optical experiments by Smith & Parker have provided new information on Ca 2+ release from clustered IP 3 Rs. In the present paper, we use the model recently introduced by Solovey & Ponce Dawson to determine how the distribution of the number of IP 3 Rs that become open during a localized release event may change by the presence of Ca 2+ buffers, substances that react with Ca 2+ , altering its concentration and transport properties. We then discuss how buffer properties could be extracted from the observation of local signals.

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The odd one in: re-diagnosis and phylogenetic placement of the Assam Day Gecko, Cnemaspis assamensis Das & Sengupta 2000 (Squamata: Gekkonidae)

Zootaxa ◽

10.11646/zootaxa.5048.4.7 ◽

2021 ◽

Vol 5048 (4) ◽

pp. 581-593

Author(s):

SHRUTI SENGUPTA ◽

JAYADITYA PURAKAYASTA ◽

NITESH ANANDAN ◽

MADHURIMA DAS ◽

KIN ONN CHAN ◽

...

Keyword(s):

Sri Lanka ◽

Mitochondrial Gene ◽

Original Description ◽

Sister Taxon ◽

Morphological Parameters ◽

Eastern India ◽

Phylogenetic Placement ◽

New Information ◽

North Eastern ◽

Genetic Assessment

Herein we provide new information on Cnemaspis assamensis, the only species of Cnemaspis known from north-eastern India. Based on five new samples, morphological parameters are described. The species was found to have pre-cloacal and femoral pores, not accounted for in the original description. Genetic assessment of the species was made using a 914 bp fragment of the ND2 mitochondrial gene and the species was recovered as the sister taxon of the C. podihuna clade from Sri Lanka.

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Whole-GUV patch-clamping

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1609142114 ◽

2016 ◽

Vol 114 (2) ◽

pp. 328-333 ◽

Cited By ~ 21

Author(s):

Matthias Garten ◽

Lars D. Mosgaard ◽

Thomas Bornschlögl ◽

Stéphane Dieudonné ◽

Patricia Bassereau ◽

...

Keyword(s):

Ion Transport ◽

Ion Channel ◽

High Resistance ◽

Membrane Properties ◽

Membrane Tension ◽

Patch Clamping ◽

Membrane Composition ◽

Residual Solvent ◽

Voltage Dependent

Studying how the membrane modulates ion channel and transporter activity is challenging because cells actively regulate membrane properties, whereas existing in vitro systems have limitations, such as residual solvent and unphysiologically high membrane tension. Cell-sized giant unilamellar vesicles (GUVs) would be ideal for in vitro electrophysiology, but efforts to measure the membrane current of intact GUVs have been unsuccessful. In this work, two challenges for obtaining the “whole-GUV” patch-clamp configuration were identified and resolved. First, unless the patch pipette and GUV pressures are precisely matched in the GUV-attached configuration, breaking the patch membrane also ruptures the GUV. Second, GUVs shrink irreversibly because the membrane/glass adhesion creating the high-resistance seal (>1 GΩ) continuously pulls membrane into the pipette. In contrast, for cell-derived giant plasma membrane vesicles (GPMVs), breaking the patch membrane allows the GPMV contents to passivate the pipette surface, thereby dynamically blocking membrane spreading in the whole-GMPV mode. To mimic this dynamic passivation mechanism, beta-casein was encapsulated into GUVs, yielding a stable, high-resistance, whole-GUV configuration for a range of membrane compositions. Specific membrane capacitance measurements confirmed that the membranes were truly solvent-free and that membrane tension could be controlled over a physiological range. Finally, the potential for ion transport studies was tested using the model ion channel, gramicidin, and voltage-clamp fluorometry measurements were performed with a voltage-dependent fluorophore/quencher pair. Whole-GUV patch-clamping allows ion transport and other voltage-dependent processes to be studied while controlling membrane composition, tension, and shape.

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