https://tandfonline.com/doi/pdf/10.1080/14686996.2018.1553108

Self-assembly as a key player for materials nanoarchitectonics

In science and technology today, the crucial importance of the regulation of nanoscale objects and structures is well recognized. The production of functional material systems using nanoscale units can be achieved via the fusion of nanotechnology with the other research disciplines. This task is a part of the emerging concept of nanoarchitectonics, which is a concept moving beyond the area of nanotechnology. The concept of nanoarchitectonics is supposed to involve the architecting of functional materials using nanoscale units based on the principles of nanotechnology. In this focus article, the essences of nanotechnology and nanoarchitectonics are first explained, together with their historical backgrounds. Then, several examples of material production based on the concept of nanoarchitectonics are introduced via several approaches: (i) from atomic switches to neuromorphic networks; (ii) from atomic nanostructure control to environmental and energy applications; (iii) from interfacial processes to devices; and (iv) from biomolecular assemblies to life science. Finally, perspectives relating to the final goals of the nanoarchitectonics approach are discussed.

Nanoarchitectonics: what's coming next after nanotechnology?

MOF-derived carbonaceous materials enriched with nitrogen: Preparation and applications in adsorption and catalysis

Incorporation of non-equilibrium actions in the sequence of self-assembly processes would be an effective means to establish bio-like high functionality hierarchical assemblies. As a novel methodology beyond self-assembly, nanoarchitectonics, which has as its aim the fabrication of functional materials systems from nanoscopic units through the methodological fusion of nanotechnology with other scientific disciplines including organic synthesis, supramolecular chemistry, microfabrication, and bio-process, has been applied to this strategy. The application of non-equilibrium factors to conventional self-assembly processes is discussed on the basis of examples of directed assembly, Langmuir-Blodgett assembly, and layer-by-layer assembly. In particular, examples of the fabrication of hierarchical functional structures using bio-active components such as proteins or by the combination of bio-components and two-dimensional nanomaterials, are described. Methodologies described in this review article highlight possible approaches using the nanoarchitectonics concept beyond self-assembly for creation of bio-like higher functionalities and hierarchical structural organization.

Nanoarchitectonics beyond Self‐Assembly: Challenges to Create Bio‐Like Hierarchic Organization

Mesoporous carbon nitrides (MCN) with C3 N4 stoichiometry could find applications in fields ranging from catalysis, sensing, and adsorption-separation to biotechnology. The extension of the synthesis of MCN with different nitrogen contents and chemical structures promises access to a wider range of applications. Herein we prepare mesoporous C3 N5 with a combined triazole and triazine framework via a simple self-assembly of 5-amino-1H-tetrazole (5-ATTZ). We are able to hybridize these nanostructures with graphene by using graphene-mesoporous-silica hybrids as a template to tune the electronic properties. DFT calculations and spectroscopic analyses clearly demonstrate that the C3 N5 consists of 1 triazole and 2 triazine moieties. The triazole-based mesoporous C3 N5 and its graphene hybrids are found to be highly active for oxygen reduction reaction (ORR) with a higher diffusion-limiting current density and a decreased overpotential than those of bulk g-C3 N4 .

Ordered Mesoporous C 3 N 5 with a Combined Triazole and Triazine Framework and Its Graphene Hybrids for the Oxygen Reduction Reaction (ORR).

Two-dimensional (2D) carbon nanomaterials possessing promising physical and chemical properties find applications in high-performance energy storage devices and catalysts. However, large-scale fabrication of 2D carbon nanostructures is based on a few specific carbon templates or precursors and poses a formidable challenge. Now a new bottom-up method for carbon nanosheet fabrication using a newly designed anisotropic carbon nanoring molecule, CPPhen, is presented. CPPhen was self-assembled at a dynamic air-water interface with a vortex motion to afford molecular nanosheets, which were then carbonized under inert gas flow. Their nanosheet morphologies were retained after carbonization, which has never been seen for low-molecular weight compounds. Furthermore, adding pyridine as a nitrogen dopant in the self-assembly step successfully afforded nitrogen-doped carbon nanosheets containing mainly pyridinic nitrogen species.

Carbon Nanosheets by Morphology-Retained Carbonization of Two-Dimensional Assembled Anisotropic Carbon Nanorings

Intramolecular rotation of molecules contained in a two-dimensional monolayer or a three-dimensional collapsed film at an air–water interface was investigated by in situ fluorescence spectroscopy of twisted intramolecular charge transfer (TICT) type 9-(2-carboxy-2-cyanovinyl)julolidine (CCVJ) derivatives. The TICT type molecules, CCVJ-C12 and CCVJ-Chol, that contain a linear alkyl dodecyl chain or a cholesteryl group, respectively, as their hydrophobic group, were designed and synthesized to manipulate them at the air–water interface. These lipophilized molecular rotors showed the general properties of TICT molecules in solutions that the fluorescence intensity increases with increasing viscosity of the solvent, which is induced by inhibition of internal molecular rotations. The molecular rotors CCVJ-C12 and CCVJ-Chol formed monolayers at the air–water interface and in situ fluorescence spectroscopy was performed during the in-plane compression of the monolayers. It was revealed that the monomer emissions were suppressed and only after the collapse of monolayers, excimer emission from both layers consisting of CCVJ-C12 or CCVJ-Chol was observed. Suppressed monomer emission from monolayers suggests that intramolecular rotation is not inhibited in dense ordered monolayers. Furthermore, fluorescence spectroscopy of Langmuir–Blodgett (LB) films indicated that molecular rotations are not inhibited in the monolayer transferred on the solid substrates.

Molecular rotors confined at an ordered 2D interface.

Modification of k-$$\omega $$ turbulence model for ship resistance flow predictions

Modification of k-ω\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\omega $$\end{document} turbulence model for ship r

CFD analysis has become an essential tool in ship hydrodynamics both for practical design applications and for engineering researches. However, although much efforts are being devoted to the development of turbulence modeling, universal turbulence models which can be applied to a wide class of ﬂows are not yet established. Particularly, ship ﬂows are characterized as turbulent ﬂows with separation around complex geometry and this makes the modeling even more difﬁcult. In the current ship ﬂow simulations, the turbulence model must be carefully selected from the experiences and the optimal model varies case by case. Recently, a new concept is proposed for expanding ﬂexibility and applicability of a RANS turbulence model. This approach called GEKO (GEneralized K-Omega) applies a modiﬁcation to the existing k - ω SST model by adding free parameters to control the various properties, such as separation, curvature correction, near wall treatment, and so on. Inspired by this approach, the parameter tuning of the SST model is attempted in the present study to improve the prediction capability of the k - ω turbulence model for ship resistance ﬂow applications.

Kengo Suzuki

Papers

Carbon Nanosheets by Morphology-Retained Carbonization of Two-Dimensional Assembled Anisotropic Carbon Nanorings

Molecular rotors confined at an ordered 2D interface.

Modification of k-$$\omega $$ turbulence model for ship resistance flow predictions

Modiﬁcation of k - ! turbulence model for ship resistance ﬂow predictions