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

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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Monodomain High-Aspect-Ratio 2D and 3D Ordered Porous Alumina Structures with Independently Controlled Pore Spacing and Diameter

Advanced Materials ◽

10.1002/adma.200601555 ◽

2007 ◽

Vol 19 (7) ◽

pp. 988-992 ◽

Cited By ~ 30

Author(s):

R. Krishnan ◽

C. V. Thompson

Keyword(s):

Aspect Ratio ◽

High Aspect Ratio ◽

Porous Alumina ◽

2D And 3D ◽

Ordered Porous

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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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Accelerating ion diffusion with unique three-dimensionally interconnected nanopores for self-membrane high-performance pseudocapacitors

Nanoscale ◽

10.1039/c7nr06234f ◽

2017 ◽

Vol 9 (46) ◽

pp. 18311-18317 ◽

Cited By ~ 5

Author(s):

Yuan Gao ◽

Yuanjing Lin ◽

Zehua Peng ◽

Qingfeng Zhou ◽

Zhiyong Fan

Keyword(s):

Aspect Ratio ◽

Surface Area ◽

Structural Stability ◽

High Aspect Ratio ◽

High Performance ◽

Three Dimensional ◽

Rate Capability ◽

Large Surface Area ◽

Nanoporous Structure ◽

Ion Diffusion

Three-dimensional interconnected nanoporous structure (3-D INPOS) possesses high aspect ratio, large surface area, as well as good structural stability. Profiting from its unique interconnected architecture, the 3-D INPOS pseudocapacitor achieves a largely enhanced capacitance and rate capability.

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Performance Estimation of Axial Flow Turbines

Proceedings of the Institution of Mechanical Engineers ◽

10.1243/pime_proc_1970_185_048_02 ◽

1970 ◽

Vol 185 (1) ◽

pp. 407-424 ◽

Cited By ~ 83

Author(s):

H. R. M. Craig ◽

H. J. A. Cox

Keyword(s):

Reynolds Number ◽

Aspect Ratio ◽

Gas Turbines ◽

Three Dimensional ◽

Axial Flow ◽

Performance Estimation ◽

Speed Ratio ◽

Test Results ◽

Wide Range ◽

Relevant Variables

A comprehensive method of estimating the performance of axial flow steam and gas turbines is presented, based on analysis of linear cascade tests on blading, on a number of turbine test results, and on air tests of model casings. The validity of the use of such data is briefly considered. Data are presented to allow performance estimation of actual machines over a wide range of Reynolds number, Mach number, aspect ratio and other relevant variables. The use of the method in connection with three-dimensional methods of flow estimation is considered, and data presented showing encouraging agreement between estimates and available test results. Finally ‘carpets’ are presented showing the trends in efficiencies that are attainable in turbines designed over a wide range of loading, axial velocity/blade speed ratio, Reynolds number and aspect ratio.

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High-aspect-ratio structure formation techniques for three-dimensional metal-oxide-semiconductor transistors

Microelectronic Engineering ◽

10.1016/j.mee.2006.01.270 ◽

2006 ◽

Vol 83 (4-9) ◽

pp. 1740-1744 ◽

Cited By ~ 1

Author(s):

Hideo Sunami ◽

Shunpei Matsumura ◽

Koji Yoshikawa ◽

Kiyoshi Okuyama

Keyword(s):

Aspect Ratio ◽

Metal Oxide ◽

Structure Formation ◽

High Aspect Ratio ◽

Three Dimensional ◽

Metal Oxide Semiconductor ◽

Oxide Semiconductor ◽

High Aspect Ratio Structure

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High-Aspect-Ratio Copper Via Filling Used for Three-Dimensional Chip Stacking

Journal of The Electrochemical Society ◽

10.1149/1.1572154 ◽

2003 ◽

Vol 150 (6) ◽

pp. G355 ◽

Cited By ~ 111

Author(s):

Jian-Jun Sun ◽

Kazuo Kondo ◽

Takuji Okamura ◽

SeungJin Oh ◽

Manabu Tomisaka ◽

...

Keyword(s):

Aspect Ratio ◽

High Aspect Ratio ◽

Three Dimensional

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Strong and Reversible Adhesion of Interlocked 3D-Microarchitectures

Coatings ◽

10.3390/coatings9010048 ◽

2019 ◽

Vol 9 (1) ◽

pp. 48 ◽

Cited By ~ 1

Author(s):

Minho Seong ◽

Hyun-Ha Park ◽

Insol Hwang ◽

Hoon Eui Jeong

Keyword(s):

Aspect Ratio ◽

Structural Stability ◽

High Aspect Ratio ◽

Three Dimensional ◽

Normal Direction ◽

One Dimensional ◽

Reversible Adhesion ◽

Adhesion Behavior ◽

Organic Nanomaterials ◽

Good Agreement

Diverse physical interlocking devices have recently been developed based on one-dimensional (1D), high-aspect-ratio inorganic and organic nanomaterials. Although these 1D nanomaterial-based interlocking devices can provide reliable and repeatable shear adhesion, their adhesion in the normal direction is typically very weak. In addition, the high-aspect-ratio, slender structures are mechanically less durable. In this study, we demonstrate a highly flexible and robust interlocking system that exhibits strong and reversible adhesion based on physical interlocking between three-dimensional (3D) microscale architectures. The 3D microstructures have protruding tips on their cylindrical stems, which enable tight mechanical binding between the microstructures. Based on the unique 3D architectures, the interlocking adhesives exhibit remarkable adhesion strengths in both the normal and shear directions. In addition, their adhesion is highly reversible due to the robust mechanical and structural stability of the microstructures. An analytical model is proposed to explain the measured adhesion behavior, which is in good agreement with the experimental results.

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