Rheology of Dispersions of High-Aspect-Ratio Nanofibers Assembled from Elastin-Like Double-Hydrophobic Polypeptides

Elastin-like polypeptides (ELPs) are promising candidates for fabricating tissue-engineering scaffolds that mimic the extracellular environment of elastic tissues. We have developed a “double-hydrophobic” block ELP, GPG, inspired by non-uniform distribution of two different hydrophobic domains in natural elastin. GPG has a block sequence of (VGGVG)5-(VPGXG)25-(VGGVG)5 that self-assembles to form nanofibers in water. Functional derivatives of GPG with appended amino acid motifs can also form nanofibers, a display of the block sequence’s robust self-assembling properties. However, how the block length affects fiber formation has never been clarified. This study focuses on the synthesis and characterization of a novel ELP, GPPG, in which the central sequence (VPGVG)25 is repeated twice by a short linker sequence. The self-assembly behavior and the resultant nanostructures of GPG and GPPG were when compared through circular dichroism spectroscopy, atomic force microscopy, and transmission electron microscopy. Dynamic rheology measurements revealed that the nanofiber dispersions of both GPG and GPPG at an extremely low concentration (0.034 wt%) exhibited solid-like behavior with storage modulus G′ > loss modulus G” over wide range of angular frequencies, which was most probably due to the high aspect ratio of the nanofibers that leads to the flocculation of nanofibers in the dispersion.

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Cooperative Self-Assembly of Pyridine-2,6-Diimine-Linked Macrocycles into Mechanically Robust Nanotubes

10.26434/chemrxiv.8080043 ◽

2019 ◽

Author(s):

Michael J. Strauss ◽

Darya Asheghali ◽

Austin Evans ◽

Rebecca Li ◽

Anton Chavez ◽

...

Keyword(s):

Aspect Ratio ◽

High Aspect Ratio ◽

Self Assembly ◽

Gel Permeation Chromatography ◽

Synthetic Polymers ◽

Young’S Moduli ◽

Structural Rigidity ◽

Assembly Mechanism ◽

Low Dimensionality ◽

Harsh Conditions

Nanotubes assembled from macrocyclic precursors offer a unique combination of low dimensionality, structural rigidity, and distinct interior and exterior microenvironments. Usually the weak stacking energies of macrocycles limit the length or strength of the resultant nanotubes. Imine-linked macrocycles were recently found to assemble into high-aspect ratio (>103), lyotropic nanotubes in the presence of excess acid. Yet these harsh conditions are incompatible with many functional groups and processing methods, and lower acid loadings instead catalyze macrocycle degradation. Here we report pyridine-2,6-diimine-linked macrocycles that assemble into high-aspect ratio nanotubes in the presence of less than 1 equiv of CF3CO2H per macrocycle. Analysis by gel permeation chromatography and fluorescence spectroscopy revealed a cooperative self-assembly mechanism. Nanofibers obtained by touch-spinning the pyridinium-based nanotubes exhibit Young’s moduli of 1.48 GPa, which exceeds that of many synthetic polymers and biological filaments. These findings will enable the design of structurally diverse nanotubes from synthetically accessible macrocycles.

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High-resolution particle separation by inertial focusing in high aspect ratio curved microfluidics

Scientific Reports ◽

10.1038/s41598-021-93177-w ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Javier Cruz ◽

Klas Hjort

Keyword(s):

High Resolution ◽

Aspect Ratio ◽

High Aspect Ratio ◽

Biological Fluids ◽

Essential Feature ◽

Particle Separation ◽

Size Difference ◽

Inertial Focusing ◽

Complex Samples ◽

Wide Range

AbstractThe ability to focus, separate and concentrate specific targets in a fluid is essential for the analysis of complex samples such as biological fluids, where a myriad of different particles may be present. Inertial focusing is a very promising technology for such tasks, and specially a recently presented variant, inertial focusing in High Aspect Ratio Curved systems (HARC systems), where the systems are easily engineered and focus the targets together in a stable position over a wide range of particle sizes and flow rates. However, although convenient for laser interrogation and concentration, by focusing all particles together, HARC systems lose an essential feature of inertial focusing: the possibility of particle separation by size. Within this work, we report that HARC systems not only do have the capacity to separate particles but can do so with extremely high resolution, which we demonstrate for particles with a size difference down to 80 nm. In addition to the concept for particle separation, a model considering the main flow, the secondary flow and a simplified expression for the lift force in HARC microchannels was developed and proven accurate for the prediction of the performance of the systems. The concept was also demonstrated experimentally with three different sub-micron particles (0.79, 0.92 and 1.0 µm in diameter) in silicon-glass microchannels, where the resolution in the separation could be modulated by the radius of the channel. With the capacity to focus sub-micron particles and to separate them with high resolution, we believe that inertial focusing in HARC systems is a technology with the potential to facilitate the analysis of complex fluid samples containing bioparticles like bacteria, viruses or eukaryotic organelles.

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Strength Analysis of Alternative Airframe Layouts of Regional Aircraft on the Basis of Automated Parametrical Models

Aerospace ◽

10.3390/aerospace8030080 ◽

2021 ◽

Vol 8 (3) ◽

pp. 80

Author(s):

Dmitry V. Vedernikov ◽

Alexander N. Shanygin ◽

Yury S. Mirgorodsky ◽

Mikhail D. Levchenkov

Keyword(s):

Aspect Ratio ◽

High Aspect Ratio ◽

High Performance ◽

Strength Analysis ◽

Labor Input ◽

Aerodynamic Loading ◽

Aspect Ratios ◽

Wide Range ◽

Parametrical Design

This publication presents the results of complex parametrical strength investigations of typical wings for regional aircrafts obtained by means of the new version of the four-level algorithm (FLA) with the modified module responsible for the analysis of aerodynamic loading. This version of FLA, as well as a base one, is focused on significant decreasing time and labor input of a complex strength analysis of airframes by using simultaneously different principles of decomposition. The base version includes four-level decomposition of airframe and decomposition of strength tasks. The new one realizes additional decomposition of alternative variants of load cases during the process of determination of critical load cases. Such an algorithm is very suitable for strength analysis and designing airframes of regional aircrafts having a wide range of aerodynamic concepts. Results of validation of the new version of FLA for a high-aspect-ratio wing obtained in this work confirmed high performance of the algorithm in decreasing time and labor input of strength analysis of airframes at the preliminary stages of designing. During parametrical design investigation, some interesting results for strut-braced wings having high aspect ratios were obtained.

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Self-ordered nanospike porous alumina fabricated under a new regime by an anodizing process in alkaline media

Scientific Reports ◽

10.1038/s41598-021-86696-z ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Mana Iwai ◽

Tatsuya Kikuchi ◽

Ryosuke O. Suzuki

Keyword(s):

Aspect Ratio ◽

High Aspect Ratio ◽

Porous Alumina ◽

Three Dimensional ◽

Alkaline Media ◽

Alkaline Electrolyte ◽

Subsequent Formation ◽

Interpore Distance ◽

Wide Range ◽

Ordered Porous

AbstractHigh-aspect ratio ordered nanomaterial arrays exhibit several unique physicochemical and optical properties. Porous anodic aluminum oxide (AAO) is one of the most typical ordered porous structures and can be easily fabricated by applying an electrochemical anodizing process to Al. However, the dimensional and structural controllability of conventional porous AAOs is limited to a narrow range because there are only a few electrolytes that work in this process. Here, we provide a novel anodizing method using an alkaline electrolyte, sodium tetraborate (Na2B4O7), for the fabrication of a high-aspect ratio, self-ordered nanospike porous AAO structure. This self-ordered porous AAO structure possesses a wide range of the interpore distance under a new anodizing regime, and highly ordered porous AAO structures can be fabricated using pre-nanotexturing of Al. The vertical pore walls of porous AAOs have unique nanospikes measuring several tens of nanometers in periodicity, and we demonstrate that AAO can be used as a template for the fabrication of nanomaterials with a large surface area. We also reveal that stable anodizing without the occurrence of oxide burning and the subsequent formation of uniform self-ordered AAO structures can be achieved on complicated three-dimensional substrates.

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Photopolymerization-assisted self-assembly as a strategy to obtain a dispersion of very high aspect ratio nanostructures in a polystyrene matrix

European Polymer Journal ◽

10.1016/j.eurpolymj.2018.10.037 ◽

2019 ◽

Vol 112 ◽

pp. 704-713 ◽

Cited By ~ 1

Author(s):

Ú.M. Montoya Rojo ◽

C.C. Riccardi ◽

M.D. Ninago ◽

A.E. Ciolino ◽

M.A. Villar ◽

...

Keyword(s):

Aspect Ratio ◽

High Aspect Ratio ◽

Self Assembly ◽

Polystyrene Matrix ◽

Very High

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High-aspect-ratio mushroom-like silica nanopillars immersed in air: epsilon-near-zero metamaterials mediated by a phonon-polaritonic anisotropy

RSC Advances ◽

10.1039/c9ra02494h ◽

2019 ◽

Vol 9 (29) ◽

pp. 16431-16438

Author(s):

Kota Ito ◽

Yuri Yamada ◽

Atsushi Miura ◽

Hideo Iizuka

Keyword(s):

Block Copolymers ◽

Aspect Ratio ◽

High Aspect Ratio ◽

Self Assembly ◽

Infrared Range ◽

Mid Infrared ◽

Zero Response ◽

Epsilon Near Zero

High-aspect-ratio mushroom-like silica nanopillars fabricated from self-assembly of block-copolymers exhibit a uniaxial epsilon-near-zero response in the mid-infrared range.

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