scholarly journals Insights into the Viscoelastic Peculiarities of Cyanobacterial Extracellular Polymeric Substance (EPS)

2021 ◽  
Author(s):  
Hatice Kaplan Can ◽  
Serap Kavlak ◽  
Fatma Gurbuz ◽  
Mehmet Odabaşı
Keyword(s):  
Extracellular Polymeric Substance ◽  
Viscoelastic Properties ◽  
Extracellular Polymeric Substances ◽  
Human Life ◽  
Polymeric Materials ◽  
Physiological Effect ◽  
Structure Property ◽  
Aquatic Life ◽  
Structure Property Relationships ◽  
Polymeric Substance

Abstract Extracellular polymeric substances (EPSs) can be defined as renewable, high molecular weight polymeric materials produced by bacteria and microorganisms. EPSs are composed of primarily polysaccharides and proteins, with minor amounts of nucleic acids, lipids, and humic substances. Cyanobacterial extracellular polymeric subtances have a significant physiological effect on bloom formation and stress tolerance in adverse conditions. Therefore, cyanobacterial EPS has an important factor for aquatic life, environment and human life. For these reasons, determining the structure and structure-property relationships of cyanobacterial EPS is important for understanding its behavior and performance. In this study, the identification of the structure-property relationships, thermal and viscoelastic properties of cyanobacterial extracellular polymeric substance, X-ray diffraction (XRD) analysis, differential thermal analysis (DTA) and dynamic mechanical analysis (DMA) have been performed. Viscoelastic properties of the polymeric materias have been interpreted by certain DMA parameters at a fixed frequency depending on the temperature to understand the performance of cyanobacterial EPS.

Combined TEM/SEI of polymer membranes

1984 ◽  
Vol 42 ◽  
pp. 386-387
Author(s):  
L. C. Sawyer
Keyword(s):  
Three Dimensional ◽  
Polymer Membranes ◽  
Industrial Process ◽  
Polymeric Materials ◽  
Structure Property ◽  
Shape Distribution ◽  
Structure Property Relationships ◽  
Wide Range ◽  
Fundamental Understanding ◽  
Potential Applications

Structure-property relationships are important in the process optimization and fundamental understanding of many polymeric materials, including membranes. Polymer membranes are currently being used for separation, concentration or purification in a wide range of industrial process applications. The process used to manufacture the membrane, and the polymer type, determines the morphology, which influences the membrane transport properties and potential applications. The morphology includes: pore size, shape, distribution and their overall three dimensional arrangement. Microscopical methods are needed to image the structures formed by the various processes, in order to systematically study changes in variables for specific applications.

Characterization of Metal-Oxide Nanoparticles: Synthesis and Dispersion in Polymeric Coatings

2002 ◽  
Vol 740 ◽  
Author(s):  
Li-Piin Sung ◽  
Stephanie Scierka ◽  
Mana Baghai-Anaraki ◽  
Derek L. Ho
Keyword(s):  
Metal Oxide ◽  
Metal Oxide Nanoparticles ◽  
Sol Gel ◽  
Polymeric Materials ◽  
Oxide Nanoparticles ◽  
Structure Property ◽  
Structure Property Relationships ◽  
Yield Information ◽  
Sol Gel Synthesis

ABSTRACTMetal-oxide nanoparticles can be used to optimize UV absorption and to enhance the stiffness, toughness, and probably the service life of polymeric materials. Characterization of the nano- and microstructure dispersion of particles is necessary to optimize the structure-property relationships. Characterizations of both TiO2 particles dispersed in an acrylic-urethane matrix and TiO2 nanostructured films obtained through sol-gel synthesis are discussed. Experimental methods include microscopy (confocal, AFM) and small angle neutron scattering (SANS). Results from SANS experiments, which yield information about the cluster size of the nano-TiO2 particles and the spatial dispersion in various nanoparticle/polymer samples are presented and compared to the results of microscopy studies.

scholarly journals Thermal and Physico-Mechanical Characterizations of Thromboresistant Polyurethane Films

2019 ◽  
Vol 6 (3) ◽  
pp. 69 ◽  
Author(s):  
Aaron C. Wilson ◽  
Shih-Feng Chou ◽  
Roberto Lozano ◽  
Jonathan Y. Chen ◽  
Pierre F. Neuenschwander
Keyword(s):  
Polymeric Materials ◽  
Fold Increase ◽  
Human Blood Plasma ◽  
Enzymatic Reactions ◽  
Structure Property ◽  
Weight Changes ◽  
Implantable Medical Devices ◽  
Structure Property Relationships ◽  
Elongation To Failure

Hemocompatibility remains a challenge for injectable and/or implantable medical devices, and thromboresistant coatings appear to be one of the most attractive methods to down-regulate the unwanted enzymatic reactions that promote the formation of blood clots. Among all polymeric materials, polyurethanes (PUs) are a class of biomaterials with excellent biocompatibility and bioinertness that are suitable for the use of thromboresistant coatings. In this work, we investigated the thermal and physico-mechanical behaviors of ester-based and ether-based PU films for potential uses in thromboresistant coatings. Our results show that poly(ester urethane) and poly(ether urethane) films exhibited characteristic peaks corresponding to their molecular configurations. Thermal characterizations suggest a two-step decomposition process for the poly(ether urethane) films. Physico-mechanical characterizations show that the surfaces of the PU films were hydrophobic with minimal weight changes in physiological conditions over 14 days. All PU films exhibited high tensile strength and large elongation to failure, attributed to their semi-crystalline structure. Finally, the in vitro clotting assays confirmed their thromboresistance with approximately 1000-fold increase in contact time with human blood plasma as compared to the glass control. Our work correlates the structure-property relationships of PU films with their excellent thromboresistant ability.

scholarly journals Functional Materials Based on Cyclometalated Platinum(II) β-Diketonate Complexes: A Review of Structure–Property Relationships and Applications

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4236
Author(s):  
Ashanul Haque ◽  
Hani El Moll ◽  
Khalaf M. Alenezi ◽  
Muhammad S. Khan ◽  
Wai-Yeung Wong
Keyword(s):  
Photophysical Properties ◽  
Functional Materials ◽  
Polymeric Materials ◽  
Organometallic Complexes ◽  
Structure Property ◽  
Covalent Bonds ◽  
Ancillary Ligands ◽  
Structure Property Relationships ◽  
Materials Research ◽  
Recent Developments

Square planar organoplatinum(II) complexes have garnered immense interest in the area of materials research. The combination of the Pt(II) fragment with mono-, bi- tri- and tetradentate organic ligands gives rise to a large variety of complexes with intriguing properties, especially cyclometalated Pt(II) complexes in which ligands are connected through covalent bonds demonstrate higher stability, excellent photoluminescence properties, and diverse applications. The properties and applications of the Pt(II)-based materials can be smartly fine-tuned via a judicious selection of the cyclometalating as well as ancillary ligands. In this review, attempts have been made to provide a brief review of the recent developments of neutral Pt(II) organometallic complexes bearing bidentate cyclometalating ligands and β-diketonate ancillary ligands, i.e., (C^N)Pt(O^O) and (C^C)Pt(O^O) derivatives. Both small (monomeric, dimeric) and large (polymeric) materials have been considered. We critically assessed the role of functionalities (ligands) on photophysical properties and their impact on applications.

scholarly journals In Situ Characterization of Differences in the Viscoelastic Response of Individual Gram-Negative and Gram-Positive Bacterial Cells

2009 ◽  
Vol 191 (17) ◽  
pp. 5518-5525 ◽  
Author(s):  
Virginia Vadillo-Rodriguez ◽  
Sarah R. Schooling ◽  
John R. Dutcher
Keyword(s):  
Viscoelastic Properties ◽  
Cell Envelope ◽  
Outer Membrane Proteins ◽  
Elastic Response ◽  
Bacterial Cells ◽  
Structure Property ◽  
Gram Positive ◽  
Gram Negative ◽  
Structure Property Relationships ◽  
Cell Envelopes

ABSTRACT We used a novel atomic force microscopy (AFM)-based technique to compare the local viscoelastic properties of individual gram-negative (Escherichia coli) and gram-positive (Bacillus subtilis) bacterial cells. We found that the viscoelastic properties of the bacterial cells are well described by a three-component mechanical model that combines an instantaneous elastic response and a delayed elastic response. These experiments have allowed us to investigate the relationship between the viscoelastic properties and the structure and composition of the cell envelope. In addition, this is the first report in which the mechanical role of Lpp, the major peptidoglycan-associated lipoprotein and one of the most abundant outer membrane proteins in E. coli cells, has been quantified. We expect that our findings will be helpful in increasing the understanding of the structure-property relationships of bacterial cell envelopes.

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