scholarly journals Complete steric exclusion of ions and proton transport through confined monolayer water

Science ◽  
2019 ◽  
Vol 363 (6423) ◽  
pp. 145-148 ◽  
Author(s):  
K. Gopinadhan ◽  
S. Hu ◽  
A. Esfandiar ◽  
M. Lozada-Hidalgo ◽  
F. C. Wang ◽  
...  
Keyword(s):  
Proton Transport ◽  
Recent Progress ◽  
Molecular Transport ◽  
Atomic Plane ◽  
Atomic Scale ◽  
Two Dimensional ◽  
Bulk Crystals ◽  
Artificial Structures ◽  
Hydrated Ions ◽  
Protein Channels

It has long been an aspirational goal to create artificial structures that allow fast permeation of water but reject even the smallest hydrated ions, replicating the feat achieved by nature in protein channels (e.g., aquaporins). Despite recent progress in creating nanoscale pores and capillaries, these structures still remain distinctly larger than protein channels. We report capillaries made by effectively extracting one atomic plane from bulk crystals, which leaves a two-dimensional slit of a few angstroms in height. Water moves through these capillaries with little resistance, whereas no permeation could be detected even for such small ions as Na+and Cl−. Only protons (H+) can diffuse through monolayer water inside the capillaries. These observations improve our understanding of molecular transport at the atomic scale.

scholarly journals Introduction

1993 ◽  
Vol 46 (3) ◽  
pp. 329
Author(s):  
D Neilson ◽  
MP Das
Keyword(s):  
Electronic Device ◽  
Thin Layers ◽  
Atomic Scale ◽  
Two Dimensional ◽  
Strong Correlations ◽  
Semiconductor Substrate ◽  
Artificial Structures ◽  
Technological Advances ◽  
Quantum Mechanical Effects ◽  
Insight Into

The subjects for this workshop were nanostructures and quasi-two-dimensional systems. Artificial nanostructures have structure on the scale of nanometres (1O~9 m). The nanometre represents a limit on the miniaturisation of artificial structures since atomic diameters are of this scale. Two-dimensional systems are atomically thin layers, usually of electrons embedded in a semiconductor substrate. These fascinating systems owe their existence to the rapid advances within the last ten years in electronic device miniaturisation and manufacture. Spectacular as the technological advances have been, the focus of the workshop was not on these achievements themselves, but on the opportunities the technology provides to think up and build artificial systems having exotic physical properties that give us insight into structure on a quantum scale. Since the atomic scale is determined by the dictates of quantum mechanics it is not surprising that artificial structures on this scale should have properties which are dominated by quantum mechanical effects and strong correlations, and that these often generate novel ground states.

Seeded Growth of Single-Crystal Two-Dimensional Covalent Organic Frameworks

2017 ◽  
Author(s):  
Austin M. Evans ◽  
Lucas R. Parent ◽  
Nathan C. Flanders ◽  
Ryan P. Bisbey ◽  
Edon Vitaku ◽  
...  
Keyword(s):  
Molecular Transport ◽  
Controlled Synthesis ◽  
Two Dimensional ◽  
Covalent Organic Frameworks ◽  
Seeded Growth ◽  
Covalent Bonds ◽  
Crystalline Materials ◽  
Step Procedure ◽  
Structures And Properties ◽  
2D Polymer

<div> <div> <div> <p>Polymerizing monomers into periodic two-dimensional (2D) networks provides structurally precise, atomically thin macromolecular sheets linked by robust, covalent bonds. These materials exhibit desirable mechanical, optoelectrotronic, and molecular transport properties derived from their designed structure and permanent porosity. 2D covalent organic frameworks (COFs) offer broad monomer scope, but are generally isolated as polycrystalline, insoluble powders with limited processability. Here we overcome this limitation by controlling 2D COF formation using a two- step procedure. In the first step, 2D COF nanoparticle seeds are prepared with approximate diameters of 30 nm. Next, monomers are slowly added to suppress new nucleation while promoting epitaxial growth on the existing seeds to sizes of several microns. The resulting COF nanoparticles are of exceptional and unprecedented quality, isolated as single crystalline materials with micron-scale domain sizes. These findings advance the controlled synthesis of 2D layered COFs and will enable a broad exploration of synthetic 2D polymer structures and properties. </p> </div> </div> </div>

Seeded Growth of Single-Crystal Two-Dimensional Covalent Organic Frameworks

2017 ◽  
Author(s):  
Austin M. Evans ◽  
Lucas R. Parent ◽  
Nathan C. Flanders ◽  
Ryan P. Bisbey ◽  
Edon Vitaku ◽  
...  
Keyword(s):  
Molecular Transport ◽  
Controlled Synthesis ◽  
Two Dimensional ◽  
Covalent Organic Frameworks ◽  
Seeded Growth ◽  
Covalent Bonds ◽  
Crystalline Materials ◽  
Step Procedure ◽  
Structures And Properties ◽  
2D Polymer

<div> <div> <div> <p>Polymerizing monomers into periodic two-dimensional (2D) networks provides structurally precise, atomically thin macromolecular sheets linked by robust, covalent bonds. These materials exhibit desirable mechanical, optoelectrotronic, and molecular transport properties derived from their designed structure and permanent porosity. 2D covalent organic frameworks (COFs) offer broad monomer scope, but are generally isolated as polycrystalline, insoluble powders with limited processability. Here we overcome this limitation by controlling 2D COF formation using a two- step procedure. In the first step, 2D COF nanoparticle seeds are prepared with approximate diameters of 30 nm. Next, monomers are slowly added to suppress new nucleation while promoting epitaxial growth on the existing seeds to sizes of several microns. The resulting COF nanoparticles are of exceptional and unprecedented quality, isolated as single crystalline materials with micron-scale domain sizes. These findings advance the controlled synthesis of 2D layered COFs and will enable a broad exploration of synthetic 2D polymer structures and properties. </p> </div> </div> </div>

Mechanics of free-standing inorganic and molecular 2D materials

Nanoscale ◽  
2021 ◽  
Author(s):  
Xianghui Zhang ◽  
Andre Beyer
Keyword(s):  
Recent Progress ◽  
Mechanical Characterization ◽  
2D Materials ◽  
Two Dimensional ◽  
Free Standing ◽  
Inorganic As

The discovery of graphene has triggered a great interest in inorganic as well as molecular two-dimensional (2D) materials. In this review, we summarize recent progress in the mechanical characterization of...

scholarly journals Template-Free Self-Assembly of Two-Dimensional Polymers into Nano/Microstructured Materials

Molecules ◽  
2021 ◽  
Vol 26 (11) ◽  
pp. 3310
Author(s):  
Shengda Liu ◽  
Jiayun Xu ◽  
Xiumei Li ◽  
Tengfei Yan ◽  
Shuangjiang Yu ◽  
...  
Keyword(s):  
Self Assembly ◽  
Recent Progress ◽  
Two Dimensional ◽  
Subsequent Removal ◽  
The Past ◽  
2D Polymers ◽  
Template Free ◽  
Self Assembled ◽  
The Relationship ◽  
Polymer Tubes

In the past few decades, enormous efforts have been made to synthesize covalent polymer nano/microstructured materials with specific morphologies, due to the relationship between their structures and functions. Up to now, the formation of most of these structures often requires either templates or preorganization in order to construct a specific structure before, and then the subsequent removal of previous templates to form a desired structure, on account of the lack of “self-error-correcting” properties of reversible interactions in polymers. The above processes are time-consuming and tedious. A template-free, self-assembled strategy as a “bottom-up” route to fabricate well-defined nano/microstructures remains a challenge. Herein, we introduce the recent progress in template-free, self-assembled nano/microstructures formed by covalent two-dimensional (2D) polymers, such as polymer capsules, polymer films, polymer tubes and polymer rings.

scholarly journals Proteomic analysis of the pulvinus, a heliotropic tissue, in Glycine max

2014 ◽  
Vol 5 (1) ◽  
Author(s):  
Hakme Lee ◽  
Wesley M. Garrett ◽  
Joseph Sullivan ◽  
Irwin Forseth ◽  
Savithiry S. Natarajan
Keyword(s):  
Mass Spectrometry ◽  
Gene Ontology ◽  
Gel Electrophoresis ◽  
Proton Transport ◽  
Enrichment Analysis ◽  
The Sun ◽  
Leaf Movement ◽  
Two Dimensional ◽  
Two Dimensional Gel Electrophoresis ◽  
Leguminous Plants

Certain plant species respond to light, dark, and other environmental factors by leaf movement. Leguminous plants both track and avoid the sun through turgor changes of the pulvinus tissue at the base of leaves. Mechanisms leading to pulvinar turgor flux, particularly knowledge of the proteins involved, are not well-known. In this study we used two-dimensional gel electrophoresis and liquid chromatography-tandom mass spectrometry to separate and identify the proteins located in the soybean pulvinus. A total of 183 spots were separated and 195 proteins from 165 spots were identified and functionally analyzed using single enrichment analysis for gene ontology terms. The most significant terms were related to proton transport. Comparison with guard cell proteomes revealed similar significant processes but a greater number of pulvinus proteins are required for comparable analysis. To our knowledge, this is a novel report on the analysis of proteins found in soybean pulvinus. These findings provide a better understanding of the proteins required for turgor change in the pulvinus.

The Elastic Moduli of Silver Thin Films Measured with a New Microtensile Tester

1991 ◽  
Vol 239 ◽  
Author(s):  
J. Ruud ◽  
D. Josell ◽  
A. L. Greer ◽  
F. Spaepen
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Diffraction Grating ◽  
Strain Measurement ◽  
Elastic Moduli ◽  
Two Dimensional ◽  
Bulk Crystals ◽  
Free Standing ◽  
Tensile Direction ◽  
Silver Thin Films

ABSTRACTA new design for a thin film microtensile tester is presented. The strain is measured directly on the free-standing thin film from the displacement of laser spots diffracted from a thin grating applied to its surface by photolithography. The diffraction grating is two-dimensional, allowing strain measurement both along and transverse to the tensile direction. In principle, both Young's modulus and Poisson's ratio of a thin film can be determined. Ag thin films with strong <111> texture were tested. The measured Young moduli agreed with those measured on bulk crystals, but the measured Poisson ratios were low, most likely due to slight transverse folding of the film that developed during the test.

scholarly journals Recent progress in epitaxial growth of two‐dimensional phosphorus

SmartMat ◽  
2021 ◽  
Author(s):  
Yihe Wang ◽  
Shuo Sun ◽  
Jialin Zhang ◽  
Yu Li Huang ◽  
Wei Chen
Keyword(s):  
Epitaxial Growth ◽  
Recent Progress ◽  
Two Dimensional

Tuning magnetism at the two-dimensional limit: A theoretical perspective

Nanoscale ◽  
2021 ◽  
Author(s):  
Dongzhe Li ◽  
Shuo Li ◽  
Chengyong Zhong ◽  
Junjie He
Keyword(s):  
Magnetic Properties ◽  
Magnetic Materials ◽  
Recent Progress ◽  
Theoretical Perspective ◽  
Two Dimensional

The discovery of two-dimensional (2D) magnetic materials provides an ideal testbed for manipulating the magnetic properties at the atomically thin and the 2D limit. This review gives recent progress on...

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