Strain-induced structural transformation of a silver nanowire

We have investigated the structural characteristics of the experimentally observed phase transition of a silver nanowire into a tube under tensile strain. In the simulations, atoms are allowed to interact via a model potential extracted from the modified embedded atom method. Our calculations demonstrate that the formation of the hollow structure is governed by the nature of the applied strain, the length of the wire, and the initial cross-sectional shape. The results further offer insights into the atomistic nature of this specific structural transformation into a nanotube with the smallest possible cross-section

Shape-controlled growth of metal nanoparticles: an atomistic view

Recent developments in shape-controlled synthesis of metallic nano-particles present a promising path for precisely tuning chemical activity, selectivity, and stability of nano-materials. While previous studies have highlighted the macroscopic description of synthesis processes, there is less understanding as to whether individual atomic-scale processes posses any signicant role in controlling growth of nano-products. The presented molecular static and dynamic simulations are the rst simulations to understand the underlying atomistic mechanisms of the experimentally determined growth modes of metal nano-clusters. Our simulations on Ag nano-cubes conrm that metal nano-seeds enclosed by {100} facets can be directed to grow into octopod, concave, truncated cube, and cuboctahedron when the relative surface diusion and deposition rates are nely tuned. Here we further showed that atomic level processes play a signicant role in controllably ne tuning the two competing rates: surface diusion and deposition. We also found that regardless of temperature and initial shape of the nano-seeds, the exchange of the deposited atom with an edge atom of the seed is by far the governing diusion mechanism between the neighboring facets, and thus is the leading atomistic process determining the conditions for ne tuning of macroscopic processes

The role of atomistic processes in growth of Cu–Ni metallic/bimetallic nanoparticles

Controlling the morphology of non-noble bimetallic nanocrystals can provide an excellent opportunity to improve performance and activity in catalytic reactions. Although several studies have focused on the overall macroscopic description of the synthesis process, identifying the leading factors in a typical crystal growth process at the atomic scale is still challenging. Here we report the results of atomic scale calculations on the shape evolution of bimetallic Cu–Ni nanoparticle growth using molecular static and dynamic simulations. Our calculations show that statistical analysis of space and time characteristics of single atom diffusion mechanisms and their energy barriers provide sound guidance for fabricating end products with specific shapes and architecture in a growth process

Growth and shape stability of Cu-Ni core-shell nanoparticles: an atomistic perspective

The growth and shape stability of bi-metallic cubic Cu-Ni nanoparticles are studied using atomic-level simulations. Cubic nano-crystals coated with an ultra-thin Cu layer can be readily obtained when Ni cubic nanoparticles are used as the seeds. At elevated temperatures, the Cu seed with extending Ni branches preserves its shape compared to the Ni seed with extending Cu branches

Acetamiprid Poisoning Followed By Prolonged Muscle Weakness

Neonicotinoids, a new insecticide group, are considered to possess a low toxicity profile for humans. In this paper, a 41-year-old female patient who was treated for prolonged muscle weakness at an intensive care unit for 22 days and discharged without any sequela following oral acetamiprid intake for suicidal purposes is reported. After developing a clinical picture similar to the intermediate syndrome seen in organophosphate poisoning, the patient recovered with the help of symptomatic and supportive treatment

Molecular Dynamics Simulations of Carbon Nanotube Reinforced Polymer Composites

Aim of this study is to investigate the elastic properties of carbon nanotube (CNT) reinforced PEEK (Poly-Ether-Ether-Ketone) composites. For this purpose, first the elastic properties of CNTs are examined at temperatures 0 K and 300 K using Molecular Dynamics (MD) simulation technique. Then the physical and mechanical properties of PEEK bulk matrix are investigated once again with the MD approach. Having studied the CNT and the PEEK separately, the CNT-PEEK interface is examined by using both the Density Functional Theory (DFT) and MD method

A comparative study of the polymer-nanotube interface through a reactive force field and density functional theory

As nanofabrication techniques progress, systems at the nanoscale find a rapidly increasing number of applications in various areas of technology. A particularly spectacular example of this phenomenon is carbon nanotubes (CNTs), tiny graphene sheets rolled up into single-or multi-walled cylinders. So far, CNTs have been used in diverse applications in device technology, drug delivery, field emission, air and water filtration, and many others. In addition to their unusual electronic properties, CNTs also possess extremely high axial strengths and are often used as strengthening agents in various host materials. In this talk, I will present results from a joint project run in the Aeroscape Engineering and Physics Departments on the reinforcement of polymer matrices by carbon nanotubes. We conduct molecular dynamics (MD) and density functional theory (DFT) calculations to model the interaction between the polyetheretherketone (PEEK) polymer and single-walled CNTs. Our study serves not only to understand the physical properties of this novel interface such as adhesion energies, but also as a test of the REAXFF empirical potential (CHO and LG variants) against DFT studies. Following a brief introduction of the problem, I will first show results from our benchmark studies on the elastic properties of the two components separately, namely PEEK and CNTs. I will then present our finding on the interface, starting with a single polymer on a graphene sheet

Two-Dimensional Fluorinated Boron Sheets: Mechanical, Electronic, and Thermal Properties

The synthesis of atomically thin boron sheets on a silver substrate opened a new area in the field of two-dimensional systems. Similar to hydrogenated and halogenated graphene, the uniform coating of borophene with fluorine atoms can lead to new derivatives of borophene with novel properties. In this respect, we explore the possible structures of fluorinated borophene for varying levels of coverage (B_<i>n</i>F) by using first-principles methods. Following the structural optimizations, phonon spectrum analysis and ab initio molecular dynamics simulations are performed to reveal the stability of the obtained structures. Our results indicate that while fully fluorinated borophene (BF) cannot be obtained, stable configurations with lower coverage levels (B₄F and B₂F) can be attained. Unveiling the stable structures, we explore the mechanical, electronic, and thermal properties of (B_<i>n</i>F). Fluorination significantly alters the mechanical properties of the system, and remarkable results, including direction-dependent variation of Young’s modulus and a switch from a negative to positive Poisson’s ratio, are obtained. However, the metallic character is preserved for low coverage levels, and metal to semiconductor transition is obtained for B₂F. The heat capacity at a low temperature increases with an increasing F atom amount but converges to the same limiting value at high temperatures. The enhanced stability and unique properties of fluorinated borophene make it a promising material for various high-technology applications in reduced dimensions