scholarly journals Atomistic Simulations of Mechanics of Nanostructures

MRS Bulletin ◽  
2009 ◽  
Vol 34 (3) ◽  
pp. 160-166 ◽  
Author(s):  
Hanchen Huang ◽  
Helena Van Swygenhoven
Keyword(s):  
Deformation Mechanism ◽  
Bulk Material ◽  
Atomistic Simulations ◽  
Ideal Strength ◽  
Electronic Level ◽  
Nanostructure Materials ◽  
Common Features ◽  
Surfaces And Interfaces ◽  
Insight Into

AbstractNanostructures can be in the form of nanoparticles or nanograins, nanowires or nanotubes, and nanoplates or multilayers. These nanostructures may be used individually or embedded in a bulk material. In both cases, they share two common features. First, the small dimensions minimize or even eliminate the presence of defects. Second, nanostructures entail large surface or interface areas. The absence of defects makes nanostructure materials stronger than their bulk counterparts, leading to the eventual realization of ideal strength. The presence of surfaces and interfaces may either reduce or increase the strength. Atomistic simulations can provide insight into the deformation mechanism at the atomic and electronic level, something that is very difficult to obtain from experiments. This article describes generic features of nanostructures and summarizes the five areas presented in the articles in this issue.

scholarly journals Social Polarisation at the Local Level: A Four-Town Comparative Study on the Challenges of Politicising Inequality in Britain

Sociology ◽  
2020 ◽  
pp. 003803852097559 ◽  
Author(s):  
Insa Koch ◽  
Mark Fransham ◽  
Sarah Cant ◽  
Jill Ebrey ◽  
Luna Glucksberg ◽  
...  
Keyword(s):  
Comparative Study ◽  
Local Level ◽  
Social Groups ◽  
Community Analysis ◽  
Common Features ◽  
Social Polarisation ◽  
The Uk ◽  
Missing Middle ◽  
Insight Into

This article examines how intensifying inequality in the UK plays out at a local level, in order to bring out the varied ways polarisation takes place ‘on the ground’. It brings a community analysis buttressed by quantitative framing to the study of economic, spatial and relational polarisation in four towns in the UK. We distinguish differing dynamics of ‘elite-based’ polarisation (in Oxford and Tunbridge Wells) and ‘poverty-based’ polarisation (in Margate and Oldham). Yet there are also common features. Across the towns, marginalised communities express a sense of local belonging. But tensions between social groups also remain strong and all towns are marked by a weak or ‘squeezed middle’. We argue that the weakness of intermediary institutions, including but not limited to the ‘missing middle’, and capable of bridging gaps between various social groups, provides a major insight into both the obstacles to, and potential solutions for, re-politicising inequality today.

scholarly journals Between Knowledge and Use of Iban and Malay Multiword Expression: An Insight into L1 and L2 Acquisition and Competence

2017 ◽  
Vol 6 (2) ◽  
Author(s):  
Shanthi Nadarajan ◽  
Fiona Balan
Keyword(s):  
Local Knowledge ◽  
Written Language ◽  
Questionnaire Data ◽  
L2 Acquisition ◽  
Common Features ◽  
Multiword Expressions ◽  
Formal Instruction ◽  
Schooling Experience ◽  
L1 And L2 ◽  
Insight Into

This article examines usage and use of multiword expressions (MWE) among Iban youths in Sarawak. The questionnaire data were from 80 Iban youths who had to identify 15 MWE (similar, nearly similar and different) in Malay and Iban, and use them at the word, phrase and sentence levels. The findings revealed that close to 67% of the respondents could not recognise or use expressions in Iban, suggesting some loss of productive knowledge and language empowerment. However, respondents with recent schooling experience were able to use the expressions in Malay and reproduce them in written forms. Formal instruction and the written language have helped to extend local knowledge and use of MWE expressions for Iban youths. The study suggests that documentation, preservation and maintenance efforts stand to benefit when there is greater sharing and consciousness raising of common features between and among languages in the region.

Atomistic simulations of deformation mechanism of fcc/bcc dual-phase high-entropy alloy multilayers

2021 ◽  
Vol 130 (24) ◽  
pp. 244301
Author(s):  
B. Ding ◽  
H. Y. Song ◽  
M. R. An ◽  
M. X. Xiao ◽  
Y. L. Li
Keyword(s):  
Deformation Mechanism ◽  
Atomistic Simulations ◽  
High Entropy Alloy ◽  
Dual Phase ◽  
High Entropy

scholarly journals Magnesium-rich nanoprecipitates in calcite: atomistic mechanisms responsible for toughening in Ophiocoma wendtii

2020 ◽  
Vol 22 (18) ◽  
pp. 10056-10062 ◽  
Author(s):  
Alexander Broad ◽  
Ian J. Ford ◽  
Dorothy M. Duffy ◽  
Robert Darkins
Keyword(s):  
Crack Propagation ◽  
Atomistic Simulations ◽  
Ophiocoma Wendtii ◽  
Insight Into

Atomistic simulations provide insight into an example of the superiority of biogenic crystals, where Mg-rich nanoprecipitates in calcite inhibit crack propagation.

Atomistic Simulations for Multiscale Modeling in bcc Metals

1999 ◽  
Vol 121 (2) ◽  
pp. 120-125 ◽  
Author(s):  
John A. Moriarty ◽  
Wei Xu ◽  
Per So¨derlind ◽  
James Belak ◽  
Lin H. Yang ◽  
...  
Keyword(s):  
Multiscale Modeling ◽  
Strength Properties ◽  
Peierls Stress ◽  
Boundary Structure ◽  
Atomistic Simulations ◽  
Interatomic Potentials ◽  
Ideal Strength ◽  
Bcc Metals ◽  
Kink Pair ◽  
Grain Boundary Structure

Quantum-based atomistic simulations are being used to study fundamental deformation and defect properties relevant to the multiscale modeling of plasticity in bcc metals at both ambient and extreme conditions. Ab initio electronic-structure calculations on the elastic and ideal-strength properties of Ta and Mo help constrain and validate many-body interatomic potentials used to study grain boundaries and dislocations. The predicted Σ5 (310) [100] grain boundary structure for Mo has recently been confirmed in HREM measurements. The core structure, γ surfaces, Peierls stress, and kink-pair formation energies associated with the motion of a/2〈111〉 screw dislocations in Ta and Mo have also been calculated. Dislocation mobility and dislocation junction formation and breaking are currently under investigation.

Structure of the Mean Velocity and Turbulence in Premixed Axisymmetric Acetylene Flames

1994 ◽  
Vol 116 (3) ◽  
pp. 631-642 ◽  
Author(s):  
M. Matovic ◽  
S. Oka ◽  
F. Durst
Keyword(s):  
Flow Field ◽  
Probability Density ◽  
Turbulent Velocity ◽  
Mean Velocity ◽  
Velocity Fluctuations ◽  
Common Features ◽  
Density Distributions ◽  
The Mean ◽  
Probability Density Distributions ◽  
Insight Into

Laser-Doppler measurements of axial mean velocities and the corresponding rms values of turbulent velocity fluctuations are reported for premixed, axisymmetric, acetylene flames together with the probability density distributions of the turbulent velocity fluctuations. All this information provides an insight into the structure of the flow field. Characteristic zones of the flow field are defined that show common features for all acetylene flames studied by the authors. These features are discussed in the paper and are suggested to characterize, in general, interesting parts of the flames.

Description of Crystallographic Morphologies of Product Phases with Singularity and Δg Distribution

2011 ◽  
Vol 172-174 ◽  
pp. 1096-1105 ◽  
Author(s):  
Wen Zheng Zhang ◽  
Zhang Zhi Shi
Keyword(s):  
Interfacial Structure ◽  
Vicinal Surface ◽  
Wulff Construction ◽  
Common Features ◽  
Surfaces And Interfaces ◽  
The Common ◽  
Diffraction Patterns ◽  
Lattice Planes ◽  
Kinetic Effects ◽  
Special Arrangement

Product phases from various phase transformations often exhibit fascinating morphologies. Facets of unique crystallographic orientations are characteristic of the morphologies. Based on a comparison of facets in the surfaces and interfaces of crystals, this paper proposes to use singularity as the common features of facets on a crystal. While association of facets with energy singularity has been established from the Wulff construction, we defined singularity in structure with an absence of one or more types of defects common to a vicinal surface or interface. Singularity in an interfacial structure is described in terms of both ledges and dislocations. When dislocations are involved, the candidates of the singular interfaces derive mainly from the principal O-lattice planes. The orientations of these planes are defined by Δg’s, which are measurable in diffraction patterns. Singularity with respect to the orientation relationship results from further eliminating defects, which is permitted by a special arrangement of Δg’s. The candidates of singular interface confined by the arrangement of discrete Δg’s are helpful for understanding the crystallographic morphology. One example from an Mg alloy is provided to show the association of the singular interfaces with Δg’s. The effect of the potential presence of a long-range strain and kinetic effects are briefly discussed.

scholarly journals Ideal Strength and Deformation Mechanism in High-Efficiency Thermoelectric SnSe

2017 ◽  
Vol 29 (5) ◽  
pp. 2382-2389 ◽  
Author(s):  
Guodong Li ◽  
Umut Aydemir ◽  
Max Wood ◽  
William A. Goddard ◽  
Pengcheng Zhai ◽  
...  
Keyword(s):  
Deformation Mechanism ◽  
High Efficiency ◽  
Ideal Strength ◽  
Strength And Deformation

scholarly journals Molecular photoswitches mediating the strain-driven disassembly of supramolecular tubules

2017 ◽  
Vol 114 (45) ◽  
pp. 11850-11855 ◽  
Author(s):  
Jean W. Fredy ◽  
Alejandro Méndez-Ardoy ◽  
Supaporn Kwangmettatam ◽  
Davide Bochicchio ◽  
Benjamin Matt ◽  
...  
Keyword(s):  
Essential Feature ◽  
Operation Mode ◽  
Building Blocks ◽  
Water Soluble ◽  
Atomistic Simulations ◽  
Supramolecular Architecture ◽  
Mechanical Responses ◽  
Pulling Forces ◽  
Nonlinear Operation ◽  
Insight Into

Chemists have created molecular machines and switches with specific mechanical responses that were typically demonstrated in solution, where mechanically relevant motion is dissipated in the Brownian storm. The next challenge consists of designing specific mechanisms through which the action of individual molecules is transmitted to a supramolecular architecture, with a sense of directionality. Cellular microtubules are capable of meeting such a challenge. While their capacity to generate pushing forces by ratcheting growth is well known, conversely these versatile machines can also pull microscopic objects apart through a burst of their rigid tubular structure. One essential feature of this disassembling mechanism is the accumulation of strain in the tubules, which develops when tubulin dimers change shape, triggered by a hydrolysis event. We envision a strategy toward supramolecular machines generating directional pulling forces by harnessing the mechanically purposeful motion of molecular switches in supramolecular tubules. Here, we report on wholly synthetic, water-soluble, and chiral tubules that incorporate photoswitchable building blocks in their supramolecular architecture. Under illumination, these tubules display a nonlinear operation mode, by which light is transformed into units of strain by the shape changes of individual switches, until a threshold is reached and the tubules unleash the strain energy. The operation of this wholly synthetic and stripped-down system compares to the conformational wave by which cellular microtubules disassemble. Additionally, atomistic simulations provide molecular insight into how strain accumulates to induce destabilization. Our findings pave the way toward supramolecular machines that would photogenerate pulling forces, at the nanoscale and beyond.

scholarly journals Heritage of the Soviet Ideology in parenting nowadays : the case of Latvia

2015 ◽  
Vol 3 ◽  
pp. 304
Author(s):  
Zanda Rubene ◽  
Nora Jansone-Ratinika ◽  
Ilze Dinka
Keyword(s):  
Public Sphere ◽  
Family Life ◽  
Soviet Period ◽  
Social Transformations ◽  
Pedagogical Discourse ◽  
Common Features ◽  
Pedagogical Competence ◽  
History Of ◽  
Soviet Ideology ◽  
Insight Into

The Soviet period has shaped the history of Latvia in different areas. This article offers an insight into the ideological heritage which has significantly transformed the pedagogical discourse in theoretical as well as instrumental level. Article describes a part of two researches “Social transformations of the child's image in children's room” and “Father`s Pedagogical Competence in Family Nowadays”, revealing common features characterizing Soviet issues. Narrative explores crucial systemic changes, transformation of social and family life, deals with the deformed relationship between individuals in public sphere and family members in private and shows consequences still actual nowadays, pointing out the question of gendered and “Sovietized” identities.

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