scholarly journals Surface energy and wettability of van der Waals structures

Nanoscale ◽  
2016 ◽  
Vol 8 (10) ◽  
pp. 5764-5770 ◽  
Author(s):  
Meenakshi Annamalai ◽  
Kalon Gopinadhan ◽  
Sang A. Han ◽  
Surajit Saha ◽  
Hye Jeong Park ◽  
...  
Keyword(s):  
Surface Energy ◽  
Van Der Waals ◽  
Van Der Waals Forces ◽  
Layered Materials ◽  
2D Layered Materials ◽  
Dipole Interactions

Our study shows that the surface energy of all 2D layered materials is undoubtedly dominated by London–van der Waals forces with little contribution from dipole–dipole interactions.

Pull-In Instability of Functionally Graded Cantilever Nanoactuators Incorporating Effects of Microstructure, Surface Energy and Intermolecular Forces

2018 ◽  
Vol 10 (08) ◽  
pp. 1850091 ◽  
Author(s):  
Mohamed A. Attia ◽  
Salwa A. Mohamed
Keyword(s):  
Residual Stress ◽  
Surface Energy ◽  
Boundary Conditions ◽  
Van Der Waals ◽  
Surface Elasticity ◽  
Van Der Waals Forces ◽  
Functionally Graded ◽  
Surface Residual Stress ◽  
Electrically Actuated ◽  
Classical Boundary

In this paper, an integrated non-classical continuum model is developed to investigate the pull-in instability of electrostatically actuated functionally graded nanocantilevers. The model accounts for the simultaneous effects of local-microstructure, surface elasticity and surface residual in the presence of fringing field as well as Casimir and van der Waals forces. The modified couple stress and Gurtin–Murdoch surface elasticity theories are employed to conduct the scaling effects of microstructure and surface energy, respectively, in the context of Euler–Bernoulli beam hypothesis. Bulk and surface material properties are varied according to the power-law distribution through the beam thickness. The physical neutral axis position for mentioned FG nanobeams is considered. Hamilton principle is employed to derive the nonlinear size-dependent governing equations and the non-classical boundary conditions. The resulting nonlinear differential equations are solved utilizing the generalized differential quadrature method (GDQM). In addition, the non-classical boundary conditions of nanocantilever beams due to surface residual stress are exactly implemented. After validation of the obtained results by previously available data in the literature, the influences of different geometrical and material parameters on the pull-in instability of the FG nanocantilevers are examined in detail. It is concluded that the pull-in behavior of electrically actuated FG micro/nanocantilevers is significantly influenced by the material distribution, material length scale parameter, surface elasticity constant, surface residual stress, initial gap, slenderness ratio, Casimir, and van der Waals forces. The obtained results can be considered for modeling and analysis of electrically actuated FG nanocantilevers.

scholarly journals Interfacial Engineering of Van der Waals Coupled 2D Layered Materials

2017 ◽  
Vol 4 (9) ◽  
pp. 1601054 ◽  
Author(s):  
Hao Hong ◽  
Can Liu ◽  
Ting Cao ◽  
Chenhao Jin ◽  
Shaoxin Wang ◽  
...  
Keyword(s):  
Van Der Waals ◽  
Layered Materials ◽  
Interfacial Engineering ◽  
2D Layered Materials

scholarly journals van der Waals forces influencing adhesion of cells

2015 ◽  
Vol 370 (1661) ◽  
pp. 20140078 ◽  
Author(s):  
K. Kendall ◽  
A. D. Roberts
Keyword(s):  
Cell Adhesion ◽  
Surface Energy ◽  
Adhesion Molecules ◽  
Adhesion Force ◽  
Van Der Waals ◽  
Van Der Waals Forces ◽  
Surface Molecules ◽  
Molecular Adhesion ◽  
Surface Active ◽  
Water Cut

Adhesion molecules, often thought to be acting by a ‘lock and key’ mechanism, have been thought to control the adhesion of cells. While there is no doubt that a coating of adhesion molecules such as fibronectin on a surface affects cell adhesion, this paper aims to show that such surface contamination is only one factor in the equation. Starting from the baseline idea that van der Waals force is a ubiquitous attraction between all molecules, and thereby must contribute to cell adhesion, it is clear that effects from geometry, elasticity and surface molecules must all add on to the basic cell attractive force. These effects of geometry, elasticity and surface molecules are analysed. The adhesion force measured between macroscopic polymer spheres was found to be strongest when the surfaces were absolutely smooth and clean, with no projecting protruberances. Values of the measured surface energy were then about 35 mJ m −2 , as expected for van der Waals attractions between the non-polar molecules. Surface projections such as abrasion roughness or dust reduced the molecular adhesion substantially. Water cut the measured surface energy to 3.4 mJ m −2 . Surface active molecules lowered the adhesion still further to less than 0.3 mJ m −2 . These observations do not support the lock and key concept.

scholarly journals Making high-quality quantum microwave devices with van der Waals superconductors

2021 ◽  
Author(s):  
Abhinandan Antony ◽  
Martin V. Gustafsson ◽  
Anjaly Rajendran ◽  
Avishai Benyamini ◽  
Guilhem Ribeill ◽  
...  
Keyword(s):  
Quantum Coherence ◽  
Van Der Waals ◽  
Layered Materials ◽  
Low Loss ◽  
High Quality ◽  
Quantum Devices ◽  
2D Layered Materials ◽  
Value Sets ◽  
Microwave Regime ◽  
Quality Factor Q

Abstract Ultra low-loss microwave materials are crucial for enhancing quantum coherence and scalability of superconducting qubits. Van der Waals (vdW) heterostructure is an attractive platform for quantum devices due to the single-crystal structure of the constituent two-dimensional (2D) layered materials and the lack of dangling bonds at their atomically sharp interfaces. However, new fabrication and characterization techniques are required to determine whether these structures can achieve low loss in the microwave regime. Here we report the fabrication of superconducting microwave resonators using NbSe$_2$ that achieve a quality factor $Q > 10^5$. This value sets an upper bound that corresponds to a resistance of $\leq 192 \mu\Omega$ when considering the additional loss introduced by integrating NbSe$_2$ into a standard transmon circuit. This work demonstrates the compatibility of 2D layered materials with high-quality microwave quantum devices.

scholarly journals Rotational superstructure in van der Waals heterostructure of self-assembled C60 monolayer on the WSe2 surface

Nanoscale ◽  
2017 ◽  
Vol 9 (35) ◽  
pp. 13245-13256 ◽  
Author(s):  
Elton J. G. Santos ◽  
Declan Scullion ◽  
Ximo S. Chu ◽  
Duo O. Li ◽  
Nathan P. Guisinger ◽  
...  
Keyword(s):  
Organic Molecules ◽  
Van Der Waals ◽  
Layered Materials ◽  
Two Dimensional ◽  
2D Layered Materials ◽  
Van Der Waals Heterostructure ◽  
Enhanced Properties ◽  
Optoelectronic Applications ◽  
Self Assembled ◽  
And Performance

Hybrid van der Waals (vdW) heterostructures composed of two-dimensional (2D) layered materials and self-assembled organic molecules are promising systems for electronic and optoelectronic applications with enhanced properties and performance.

Van der Waals stacked 2D layered materials for optoelectronics

2D Materials ◽  
2016 ◽  
Vol 3 (2) ◽  
pp. 022001 ◽  
Author(s):  
Wenjing Zhang ◽  
Qixing Wang ◽  
Yu Chen ◽  
Zhuo Wang ◽  
Andrew T S Wee
Keyword(s):  
Van Der Waals ◽  
Layered Materials ◽  
2D Layered Materials

Self-Assembly of a Chiral Cubic Three-Connected Net from the High Symmetry Molecules C60 and SnI4

2020 ◽  
Author(s):  
Daniel B. Straus ◽  
Robert J. Cava
Keyword(s):  
Organic Synthesis ◽  
Self Assembly ◽  
Van Der Waals ◽  
Van Der Waals Forces ◽  
High Symmetry ◽  
Molecular Chirality ◽  
Chiral Materials ◽  
Self Assembled ◽  
Chiral Centers

The design of new chiral materials usually requires stereoselective organic synthesis to create molecules with chiral centers. Less commonly, achiral molecules can self-assemble into chiral materials, despite the absence of intrinsic molecular chirality. Here, we demonstrate the assembly of high-symmetry molecules into a chiral van der Waals structure by synthesizing crystals of C<sub>60</sub>(SnI<sub>4</sub>)<sub>2</sub> from icosahedral buckminsterfullerene (C<sub>60</sub>) and tetrahedral SnI4 molecules through spontaneous self-assembly. The SnI<sub>4</sub> tetrahedra template the Sn atoms into a chiral cubic three-connected net of the SrSi<sub>2</sub> type that is held together by van der Waals forces. Our results represent the remarkable emergence of a self-assembled chiral material from two of the most highly symmetric molecules, demonstrating that almost any molecular, nanocrystalline, or engineered precursor can be considered when designing chiral assemblies.

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