scholarly journals Hierarchical 3D ZnO nanowire structures via fast anodization of zinc

2015 ◽  
Vol 3 (34) ◽  
pp. 17569-17577 ◽  
Author(s):  
D. O. Miles ◽  
P. J. Cameron ◽  
D. Mattia
Keyword(s):  
Growth Rates ◽  
High Surface ◽  
Three Dimensional ◽  
Electrochemical Anodization ◽  
Nanowire Growth ◽  
Controlled Synthesis ◽  
Zno Nanowire ◽  
One Dimensional ◽  
Ambient Temperatures ◽  
Surface Areas

The rapid and controlled synthesis of three-dimensional hierarchical ZnO nanowires using electrochemical anodization is reported. The stages of nanowire growth are identified and growth rates are optimised to in excess of 3 μm min−1 at ambient temperatures. The structures produced combine high surface areas with the benefits of one-dimensional nanowires and have potential application in photocatalysis, photovoltaics and sensing.

On the stability of nonlinear waves coexisting with plasma beams

1975 ◽  
Vol 13 (1) ◽  
pp. 173-187 ◽  
Author(s):  
E. Infeld ◽  
G. Rowlands
Keyword(s):  
Nonlinear Wave ◽  
Growth Rates ◽  
Three Dimensional ◽  
Stationary Waves ◽  
One Dimensional ◽  
Long Wavelength ◽  
Long Wave ◽  
Set Up ◽  
The Stability ◽  
The One

In this paper we consider the stability of one-dimensional stationary waves set up by two counter-streaming beams of electrons in a background of stationary ions. The perturbations considered are long-wave in a direction perpendicular to the wave. The presence of a uniform magnetic field in the direction of the wave and the effect of a perpendicular pressure are taken into account. In the long-wavelength limit growth rates are diminished by the nonlinear wave. When the amplitude of this wave tends to its maximum value, the growth rates tend to zero. Thus the wave has a stabilizing effect for long-wave perturbations. Three- dimensional effects lead to additional instabilities which are also quenched by the nonlinear wave, but not as fast as the one-dimensional calculation indicates.

Enhanced visible-light photocatalytic hydrogen production activity of three-dimensional mesoporous p-CuS/n-CdS nanocrystal assemblies

2017 ◽  
Vol 4 (3) ◽  
pp. 433-441 ◽  
Author(s):  
Ioannis Vamvasakis ◽  
Adelais Trapali ◽  
Jianwei Miao ◽  
Bin Liu ◽  
Gerasimos S. Armatas
Keyword(s):  
Hydrogen Production ◽  
Visible Light ◽  
High Performance ◽  
Hydrogen Generation ◽  
High Surface ◽  
Three Dimensional ◽  
Surface Areas ◽  
Photocatalytic Hydrogen Generation ◽  
Production Activity ◽  
Visible Light Photocatalytic

Mesoporous assemblies of p-CuS/n-CdS nanocrystal junctions with high surface areas and uniform pores demonstrate a high performance and stability in photocatalytic hydrogen generation from water using visible light.

A theoretical morphologic analysis of convergently evolved erect helical colony form in the Bryozoa

Paleobiology ◽  
2000 ◽  
Vol 26 (4) ◽  
pp. 556-577 ◽  
Author(s):  
George R. McGhee ◽  
Frank K. McKinney
Keyword(s):  
Surface Area ◽  
Dimensional Space ◽  
High Surface ◽  
High Surface Area ◽  
Three Dimensional ◽  
Filter Feeding ◽  
Colony Form ◽  
Surface Areas ◽  
Morphologic Analysis ◽  
Intermediate Surface

Exploration of the theoretical morphospace of erect helical colony form in Bryozoa, created by McKinney and Raup (1982), reveals that only a small volume of the three-dimensional space of hypothetical form is occupied by actual colonies of the Paleozoic fenestrates (Class Stenolaemata) Archimedes and Helicopora, helical species of the cheilostome (Class Gymnolaemata) Bugula, and the cyclostome (Class Stenolaemata) Crisidmonea archimediformis. Actual helical-colony bryozoans are not found in regions of the morphospace characterized by colony geometries that possess the largest surface areas of filtration sheet. Examination of computer-simulated colonies in the theoretical morphospace reveals that, although possessing high surface areas, colonies in the empty region of high-surface-area morphospace possess other aspects of geometry that are unrealistic as filter-feeding geometries: the filtration-sheet whorls are held at small acute angles to the central colony axis and are deeply nested within one another, both of which are disadvantageous conditions for the system of filter feeding used by the extant cheilostome Bugula, and presumably by extinct helical-colony bryozoans as well.Even though actual bryozoans are found only in the low to intermediate surface-area regions of the theoretical morphospace, surface area of filtration sheet is a major determinant of form in these helical colonies, as is evidenced by a negative correlation in values of the parameters BWANG and ELEV exhibited by the colony data. Minimum values of BWANG are even further constrained by the apparent need of the Archimedes colonies to maintain filtration-sheet branching densities within the range of 20 to 50.

Effective Thermal Conductivity of Fully-Saturated High Porosity Metal Foam

Volume 1 ◽  
2004 ◽  
Author(s):  
Eric N. Schmierer ◽  
Jason Paquette ◽  
Arsalan Razani ◽  
Kwang J. Kim
Keyword(s):  
Thermal Conductivity ◽  
Effective Thermal Conductivity ◽  
Metal Foam ◽  
Three Dimensional ◽  
Element Calculation ◽  
One Dimensional ◽  
Cubic Lattice ◽  
Surface Areas ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

Geometric models are used to simplify the complex, three-dimensional geometry of metal foams for calculations of effective thermal conductivity. The first is based on a conventional three-dimensional cubic lattice and the second is a tetrakaidecahedronal model. The models consist of interconnecting ligaments with a spherical node at their intersections. The geometry of the foam is determined based on two dimensionless parameters: 1) the porosity and 2) the product of the specific surface area of the foam and the length of the interconnecting ligaments. A free parameter represents the size of the lumps at the ligament interconnections. It is shown that the remaining unknown geometric parameters of the models can be obtained as a solution of a cubic equation that has only one acceptable solution. From the cubic lattice model, a one-dimensional heat conduction analytical model is used to find the effective thermal conductivity of fully saturated metal foam. A three-dimensional finite element calculation of the effective thermal conductivity for the cubic lattice is then compared to the one-dimensional model. In the case of the tetrakaidecahedronal model, a similar three-dimensional finite element calculation is performed to find the effective thermal conductivity. Anisotropy of the models is explored. The results of the models are compared with experimental results from this study and the literature to substantiate their accuracy. The experimental results are reported for fully saturated aluminum metal foam in air, water, and oil. Results show that both the cubic lattice model, which is less complex, and the tetrakaidecahedronal model can both be used to represent one-dimensional effective thermal conductivity. Finally, the dimensionless surface areas for each geometric model are compared. The models produce significantly different surface areas, and therefore do not both represent the density and specific surface area of foam accurately.

Shape-controlled synthesis of Co3O4 for enhanced electrocatalysis of the oxygen evolution reaction

2019 ◽  
Vol 55 (25) ◽  
pp. 3626-3629 ◽  
Author(s):  
Boopathi Sidhureddy ◽  
Jesse S. Dondapati ◽  
Aicheng Chen
Keyword(s):  
Oxygen Evolution ◽  
Oxygen Evolution Reaction ◽  
Three Dimensional ◽  
Controlled Synthesis ◽  
Two Dimensional ◽  
One Dimensional ◽  
Shape Controlled

One-dimensional Co3O4 nanorods, two-dimensional nanosheets and three-dimensional nanocubes were synthesized; the effect of the morphology on their electrocatalytic activities was studied.

scholarly journals TiO2 Based Nanostructures for Photocatalytic CO2 Conversion to Valuable Chemicals

Micromachines ◽  
2019 ◽  
Vol 10 (5) ◽  
pp. 326 ◽  
Author(s):  
Abdul Razzaq ◽  
Su-Il In
Keyword(s):  
Noble Metals ◽  
Photocatalytic Performance ◽  
Light Trapping ◽  
High Surface ◽  
Three Dimensional ◽  
Value Added ◽  
Co2 Conversion ◽  
Surface Areas ◽  
Tio2 Nanosheets ◽  
Photocatalytic Co2 Conversion

Photocatalytic conversion of CO2 to useful products is an alluring approach for acquiring the two-fold benefits of normalizing excess atmospheric CO2 levels and the production of solar chemicals/fuels. Therefore, photocatalytic materials are continuously being developed with enhanced performance in accordance with their respective domains. In recent years, nanostructured photocatalysts such as one dimensional (1-D), two dimensional (2-D) and three dimensional (3-D)/hierarchical have been a subject of great importance because of their explicit advantages over 0-D photocatalysts, including high surface areas, effective charge separation, directional charge transport, and light trapping/scattering effects. Furthermore, the strategy of doping (metals and non-metals), as well as coupling with a secondary material (noble metals, another semiconductor material, graphene, etc.), of nanostructured photocatalysts has resulted in an amplified photocatalytic performance. In the present review article, various titanium dioxide (TiO2)-based nanostructured photocatalysts are briefly overviewed with respect to their application in photocatalytic CO2 conversion to value-added chemicals. This review primarily focuses on the latest developments in TiO2-based nanostructures, specifically 1-D (TiO2 nanotubes, nanorods, nanowires, nanobelts etc.) and 2-D (TiO2 nanosheets, nanolayers), and the reaction conditions and analysis of key parameters and their role in the up-grading and augmentation of photocatalytic performance. Moreover, TiO2-based 3-D and/or hierarchical nanostructures for CO2 conversions are also briefly scrutinized, as they exhibit excellent performance based on the special nanostructure framework, and can be an exemplary photocatalyst architecture demonstrating an admirable performance in the near future.

scholarly journals Transition Metal Coordination Polymers with Trans-1,4-Cyclohexanedicarboxylate: Acidity-Controlled Synthesis, Structures and Properties

Materials ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 486
Author(s):  
Pavel A. Demakov ◽  
Artem S. Bogomyakov ◽  
Artem S. Urlukov ◽  
Aleksandra Yu. Andreeva ◽  
Denis G. Samsonenko ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Antiferromagnetic Coupling ◽  
Controlled Synthesis ◽  
Ambient Conditions ◽  
X Ray Diffraction ◽  
One Dimensional ◽  
X Ray ◽  
Structures And Properties ◽  
Metal Organic ◽  
Metal Coordination Polymers

Five trans-1,4-cyclohexanedicarboxylate (chdc2−) metal–organic frameworks of transition metals were synthesized in aqueous systems. A careful control of pH, reaction temperature and solvent composition were shown to direct the crystallization of a particular compound. Isostructural [Co(H2O)4(chdc)]n (1) and [Fe(H2O)4(chdc)]n (2) consist of one-dimensional hydrogen-bonded chains. Compounds [Cd(H2O)(chdc)]n∙0.5nCH3CN (3), [Mn4(H2O)3(chdc)4]n (4) and [Mn2(Hchdc)2(chdc)]n (5) possess three-dimensional framework structures. The compounds 1, 4 and 5 were further characterized by magnetochemical analysis, which reveals paramagnetic nature of these compounds. A presence of antiferromagnetic exchange at low temperatures is observed for 5 while the antiferromagnetic coupling in 4 is rather strong, even at ambient conditions. The thermal decompositions of 1, 4 and 5 were investigated and the obtained metal oxide (cubic Co3O4 and MnO) samples were analyzed by X-ray diffraction and scanning electron microscopy.

Controlled synthesis of novel one-dimensional structured ZIFs via supramolecular self-assemblies

CrystEngComm ◽  
2018 ◽  
Vol 20 (23) ◽  
pp. 3179-3186 ◽  
Author(s):  
Yali Li ◽  
Jianhua Zhu ◽  
Mingfang Cui ◽  
Jufen Yan
Keyword(s):  
Drug Delivery ◽  
Enzymatic Activity ◽  
High Surface ◽  
High Surface Area ◽  
The Self ◽  
Controlled Synthesis ◽  
One Dimensional ◽  
Drug Delivery Vehicles ◽  
Hierarchical Pores ◽  
Delivery Vehicles

Various 1D ZIF-8 nanomaterials have been synthesized via the self-templates of supramolecular self-assemblies, which exhibit hierarchical pores and high surface area. The resultant microstructures could be applied as excellent drug delivery vehicles and also as excellent carriers for enzymes with remarkable enzymatic activity.

Structure and function of neural networks in the retina

1988 ◽  
Vol 46 ◽  
pp. 26-27
Author(s):  
Peter Sterling
Keyword(s):  
Ganglion Cells ◽  
Three Dimensional ◽  
Structure And Function ◽  
Synaptic Connections ◽  
Visual Axis ◽  
One Dimensional ◽  
Cat Retina ◽  
Ultrathin Sections ◽  
And Function ◽  
Insight Into

The synaptic connections in cat retina that link photoreceptors to ganglion cells have been analyzed quantitatively. Our approach has been to prepare serial, ultrathin sections and photograph en montage at low magnification (˜2000X) in the electron microscope. Six series, 100-300 sections long, have been prepared over the last decade. They derive from different cats but always from the same region of retina, about one degree from the center of the visual axis. The material has been analyzed by reconstructing adjacent neurons in each array and then identifying systematically the synaptic connections between arrays. Most reconstructions were done manually by tracing the outlines of processes in successive sections onto acetate sheets aligned on a cartoonist's jig. The tracings were then digitized, stacked by computer, and printed with the hidden lines removed. The results have provided rather than the usual one-dimensional account of pathways, a three-dimensional account of circuits. From this has emerged insight into the functional architecture.

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