scholarly journals Membranes for Cation Transport Based on Dendronized Poly(Epichlorohydrin-Co-Ethylene Oxide). Part 2: Membrane Characterization and Transport Properties

Polymers ◽  
2021 ◽  
Vol 13 (22) ◽  
pp. 3915
Author(s):  
Alireza Zare ◽  
Xavier Montané ◽  
José Antonio Reina ◽  
Marta Giamberini
Keyword(s):  
Transport Properties ◽  
Liquid Crystalline ◽  
Linear Sweep Voltammetry ◽  
Cation Transport ◽  
Side Chain ◽  
Force Microscopy ◽  
Atomic Force ◽  
Membrane Characterization ◽  
Alkaline Cations

In this paper, we report on the preparation and characterization of membranes out of two side-chain liquid crystalline copolymers, dendronized at two different extents (20 and 40%, CP20 and CP40, respectively). The membranes were characterized by atomic force microscopy (AFM), field-emission scanning electron microscopy (FESEM), contact angle (CA) analysis, and water uptake. Moreover, transport properties were studied by methanol and proton conductivity experiment and by linear sweep voltammetry (LSV). For the sake of comparison, the behavior of the grafted copolymers was compared with the unmodified copolyether CP0 and with Nafion 117. Results demonstrated that in CP20 and CP40, cation transport depends on the presence of defined cationic channels, not affected by water presence; the comparison between LSV experiments performed with different alkaline cations suggests that CP40 possesses channels with larger diameters and better-defined inner structures.

Advances in microscopy of polymers: A FESEM and STM study

1991 ◽  
Vol 49 ◽  
pp. 1042-1043
Author(s):  
R.T. Chen ◽  
M.G. Jamieson
Keyword(s):  
Field Emission ◽  
Liquid Crystalline ◽  
Low Voltage ◽  
Polymeric Materials ◽  
Crystalline Polymer ◽  
Scanning Tunneling ◽  
Force Microscopy ◽  
Atomic Force ◽  
Microscopy Techniques

Microscopy has played a major role in establishing structure-process-property relationships in the research and development of polymeric materials. With advances in electron microscopy instrumentation (e.g., field emission SEM - FESEM) and the invention of new scanning probe microscopes (e.g., scanning tunneling microscope - STM), resolution of structures or morphologies down to the nanometer scale can be achieved with ease. This paper will focus on the application of FESEM and STM in order to understand the structure of commercial polymeric materials. Characterization of polymers using other microscopy techniques such as TEM, thermal optical microscopy and atomic force microscopy (AFM) will also be discussed.The polymeric materials evaluated in this study include membranes, liquid crystalline polymer (LCP) fibers, multiphase polymer blends and polymer films or coatings. In order to minimize beam damage and maximize contrast for surface detail in beam sensitive polymers, low voltage SEM (LVSEM) was performed on a JEOL 840F field emission SEM.

scholarly journals Preparation and Characterization of Cellulose Acetate Propionate Films Functionalized with Reactive Ionic Liquids

Polymers ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1217 ◽  
Author(s):  
Joanna Kujawa ◽  
Edyta Rynkowska ◽  
Kateryna Fatyeyeva ◽  
Katarzyna Knozowska ◽  
Andrzej Wolan ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Ionic Liquids ◽  
Transport Properties ◽  
Cellulose Acetate ◽  
Force Microscopy ◽  
Water Permeation ◽  
Atomic Force ◽  
Cellulose Acetate Propionate ◽  
Morphology Of Films

1-(1,3-diethoxy-1,3-dioxopropan-2-ylo)-3-methylimidazolium bromide (RIL1_Br), 1-(2-etoxy-2-oxoethyl)-3-methylimidazolium bromide (RIL2_Br), 1-(2-etoxy-2-oxoethyl)-3-methylimidazolium tetrafluoroborate (RIL3_BF4) ionic liquids were synthesized. Subsequently, the dense cellulose acetate propionate (CAP)-based materials containing from 9 to 28.6 wt % of these reactive ionic liquids were elaborated. Reactive ionic liquids (RILs) were immobilized in CAP as a result of the transesterification reaction. The yield of this reaction was over 90% with respect to the used RIL. The physicochemical properties of resultant films were studied using nuclear magnetic resonance (NMR), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), atomic force microscopy (AFM), and thermogravimetric analysis (TGA). The RIL incorporation influenced the morphology of films by increasing their surface roughness with the rise of RIL content. The thermal stability of CAP-based membranes was dependent on the nature of the ionic liquid. Nevertheless, it was proven that CAP films containing RILs were stable up to 120–150 °C. Transport properties were characterized by water permeation tests. It was found that the type and the amount of the ionic liquid in the CAP matrix substantially influenced the transport properties of the prepared hybrid materials.

Rapid, Refined, and Robust Method for Expression, Purification, and Characterization of Recombinant Human Amyloid-beta M1-42

2019 ◽  
Author(s):  
Priya Prakash ◽  
Travis Lantz ◽  
Krupal P. Jethava ◽  
Gaurav Chopra
Keyword(s):  
Amyloid Beta ◽  
Western Blots ◽  
Force Microscopy ◽  
E Coli ◽  
Atomic Force ◽  
Set Up ◽  
Short Time

Amyloid plaques found in the brains of Alzheimer’s disease (AD) patients primarily consists of amyloid beta 1-42 (Ab42). Commercially, Ab42 is synthetized using peptide synthesizers. We describe a robust methodology for expression of recombinant human Ab(M1-42) in Rosetta(DE3)pLysS and BL21(DE3)pLysS competent E. coli with refined and rapid analytical purification techniques. The peptide is isolated and purified from the transformed cells using an optimized set-up for reverse-phase HPLC protocol, using commonly available C18 columns, yielding high amounts of peptide (~15-20 mg per 1 L culture) in a short time. The recombinant Ab(M1-42) forms characteristic aggregates similar to synthetic Ab42 aggregates as verified by western blots and atomic force microscopy to warrant future biological use. Our rapid, refined, and robust technique to purify human Ab(M1-42) can be used to synthesize chemical probes for several downstream in vitro and in vivo assays to facilitate AD research.

scholarly journals Steady state charge conduction through solution processed liquid crystalline lanthanide bisphthalocyanine films

2019 ◽  
Vol 23 (11n12) ◽  
pp. 1603-1615
Author(s):  
Chandana Pal ◽  
Isabelle Chambrier ◽  
Andrew N. Cammidge ◽  
A. K. Sharma ◽  
Asim K. Ray
Keyword(s):  
Metal Ions ◽  
Liquid Crystalline ◽  
Microscopy Study ◽  
Individual Characteristics ◽  
Central Metal ◽  
Force Microscopy ◽  
Atomic Force ◽  
Double Decker ◽  
Order Of Magnitude ◽  
Chain Lengths

In-plane electrical characteristics of non-peripherally octyl(C[Formula: see text]H[Formula: see text]- and hexyl(C[Formula: see text]H[Formula: see text]-substituted liquid crystalline (LC) double decker lanthanide bisphthalocyanine (LnPc[Formula: see text] complexes with central metal ions lutetium (Lu), and gadolinium (Gd) have been measured in thin film formulations on interdigitated gold (Au) electrodes for the applied voltage ([Formula: see text] range of [Formula: see text]. The conduction mechanism is found to be Ohmic within the bias of [Formula: see text] while the bulk limited Poole–Frenkel mechanism is responsible for the higher bias. The compounds show individual characteristics depending on the central metal ions, substituent chain lengths and their mesophases. Values of 67.55 [Formula: see text]cm[Formula: see text] and 42.31 [Formula: see text]cm[Formula: see text] have been obtained for room temperature in-plane Ohmic conductivity of as-deposited octyl lutetium (C[Formula: see text]LuPc[Formula: see text] and hexyl gadolinium (C[Formula: see text]GdPc[Formula: see text] films, respectively while C[Formula: see text]GdPc[Formula: see text] films exhibit nearly two orders of magnitude smaller conductivity. On annealing at 80[Formula: see text]C, Ohmic conductivities of C[Formula: see text]LuPc[Formula: see text] and C[Formula: see text]GdPc[Formula: see text] are found to have increased but the conductivity of C[Formula: see text]GdPc[Formula: see text] decreased by more than one order of magnitude to 1.5 [Formula: see text]cm[Formula: see text]. For physical interpretation of the charge transport behavior of these three molecules, their UV-vis optical absorption spectra in the solution and in as-deposited and annealed solid phases and atomic force microscopy study have been performed. It is believed that both orientation and positional reorganizations are responsible, depending upon the size of the central ion and side chain length.

Stereometric characterization of Dinizia excelsa Ducke wood from Amazon rainforest using atomic force microscopy

2021 ◽  
Author(s):  
Willian Silva Conceição ◽  
Ştefan Ţălu ◽  
Robert Saraiva Matos ◽  
Glenda Quaresma Ramos ◽  
Fidel Guereiro Zayas ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Amazon Rainforest ◽  
Force Microscopy ◽  
Atomic Force ◽  
Dinizia Excelsa

scholarly journals A Universal Model for the Log-Normal Distribution of Elasticity in Polymeric Gels and Its Relevance to Mechanical Signature of Biological Tissues

Biology ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 64
Author(s):  
Arnaud Millet
Keyword(s):  
Elastic Modulus ◽  
Normal Distribution ◽  
Biological Tissues ◽  
Force Microscopy ◽  
Polymeric Gels ◽  
Atomic Force ◽  
Clear Explanation ◽  
Log Normal ◽  
Log Normal Distribution

The mechanosensitivity of cells has recently been identified as a process that could greatly influence a cell’s fate. To understand the interaction between cells and their surrounding extracellular matrix, the characterization of the mechanical properties of natural polymeric gels is needed. Atomic force microscopy (AFM) is one of the leading tools used to characterize mechanically biological tissues. It appears that the elasticity (elastic modulus) values obtained by AFM presents a log-normal distribution. Despite its ubiquity, the log-normal distribution concerning the elastic modulus of biological tissues does not have a clear explanation. In this paper, we propose a physical mechanism based on the weak universality of critical exponents in the percolation process leading to gelation. Following this, we discuss the relevance of this model for mechanical signatures of biological tissues.

In Situ Characterization of the Mechanical Behavior of Gecko's Spatulae by Atomic Force Microscopy

2013 ◽  
Vol 22 ◽  
pp. 85-93
Author(s):  
Shuang Yi Liu ◽  
Min Min Tang ◽  
Ai Kah Soh ◽  
Liang Hong
Keyword(s):  
Mechanical Behavior ◽  
Hierarchical Level ◽  
Intrinsic Properties ◽  
In Situ Characterization ◽  
Force Microscopy ◽  
Atomic Force ◽  
Theoretical Predictions ◽  
Multi Mode

In-situ characterization of the mechanical behavior of geckos spatula has been carried out in detail using multi-mode AFM system. Combining successful application of a novel AFM mode, i.e. Harmonix microscopy, the more detail elastic properties of spatula is brought to light. The results obtained show the variation of the mechanical properties on the hierarchical level of a seta, even for the different locations, pad and stalk of the spatula. A model, which has been validated using the existing experimental data and phenomena as well as theoretical predictions for geckos adhesion, crawling and self-cleaning of spatulae, is proposed in this paper. Through contrast of adhesive and craw ability of the gecko on the surfaces with different surface roughness, and measurement of the surface adhesive behaviors of Teflon, the most effective adhesion of the gecko is more dependent on the intrinsic properties of the surface which is adhered.

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