scholarly journals Mechanics of Crystalline Nanowires: An Experimental Perspective

2017 ◽  
Vol 69 (1) ◽  
Author(s):  
Yong Zhu
Keyword(s):  
Mechanical Properties ◽  
Experimental Studies ◽  
Strain Engineering ◽  
Nanoelectromechanical Systems ◽  
Stretchable Electronics ◽  
The Past ◽  
Atomic Force ◽  
Device Applications ◽  
Electron Microscopes ◽  
And Storage

A wide variety of crystalline nanowires (NWs) with outstanding mechanical properties have recently emerged. Measuring their mechanical properties and understanding their deformation mechanisms are of important relevance to many of their device applications. On the other hand, such crystalline NWs can provide an unprecedented platform for probing mechanics at the nanoscale. While challenging, the field of experimental mechanics of crystalline nanowires has emerged and seen exciting progress in the past decade. This review summarizes recent advances in this field, focusing on major experimental methods using atomic force microscope (AFM) and electron microscopes and key results on mechanics of crystalline nanowires learned from such experimental studies. Advances in several selected topics are discussed including elasticity, fracture, plasticity, and anelasticity. Finally, this review surveys some applications of crystalline nanowires such as flexible and stretchable electronics, nanocomposites, nanoelectromechanical systems (NEMS), energy harvesting and storage, and strain engineering, where mechanics plays a key role.

Mechanics of carbon nanotubes

2002 ◽  
Vol 55 (6) ◽  
pp. 495-533 ◽  
Author(s):  
Dong Qian, ◽  
Gregory J Wagner, and ◽  
Wing Kam Liu ◽  
Min-Feng Yu ◽  
Rodney S Ruoff
Keyword(s):  
Mechanical Properties ◽  
Carbon Nanotubes ◽  
Engineering Application ◽  
High Strength ◽  
Nanoelectromechanical Systems ◽  
Reinforced Polymers ◽  
Simulation Tools ◽  
The Past ◽  
Challenging Tasks ◽  
Theoretical Predictions

Soon after the discovery of carbon nanotubes, it was realized that the theoretically predicted mechanical properties of these interesting structures–including high strength, high stiffness, low density and structural perfection–could make them ideal for a wealth of technological applications. The experimental verification, and in some cases refutation, of these predictions, along with a number of computer simulation methods applied to their modeling, has led over the past decade to an improved but by no means complete understanding of the mechanics of carbon nanotubes. We review the theoretical predictions and discuss the experimental techniques that are most often used for the challenging tasks of visualizing and manipulating these tiny structures. We also outline the computational approaches that have been taken, including ab initio quantum mechanical simulations, classical molecular dynamics, and continuum models. The development of multiscale and multiphysics models and simulation tools naturally arises as a result of the link between basic scientific research and engineering application; while this issue is still under intensive study, we present here some of the approaches to this topic. Our concentration throughout is on the exploration of mechanical properties such as Young’s modulus, bending stiffness, buckling criteria, and tensile and compressive strengths. Finally, we discuss several examples of exciting applications that take advantage of these properties, including nanoropes, filled nanotubes, nanoelectromechanical systems, nanosensors, and nanotube-reinforced polymers. This review article cites 349 references.

scholarly journals Atomic Force Microscopy of Structural-Mechanical Properties of Polyethylene Reinforced by Silicate Needle-Shaped Filler

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Ilya A. Morozov ◽  
Oleg K. Garishin ◽  
Vladimir V. Shadrin ◽  
Victor A. Gerasin ◽  
Maria A. Guseva
Keyword(s):  
Mechanical Properties ◽  
Atomic Force Microscopy ◽  
Mass Fraction ◽  
Experimental Studies ◽  
Smooth Surfaces ◽  
Force Microscopy ◽  
Atomic Force ◽  
High Elongation ◽  
Cooling Procedure ◽  
Properties Of Composites

The paper presents the results of experimental studies of polyethylene-based composites reinforced with silicate needle-shaped filler (palygorskite) of different mass fraction (0, 5, 10, and 15%). These composites are less flammable and fire toxic than unfilled polyethylene. The structure (size, shape, and agglomeration of filler) and local mechanical properties of composites in nonstretched and elongated states were investigated by AFM. In stretched samples palygorskite takes a wavy shape, and at extremely high elongation the filler is orthogonal to the axis of tension. The smooth surfaces of the samples, required for AFM, were prepared using the heating/cooling procedure.

Quantitatively Studying Nano-mechanical Properties within the Prism and Organic Sheath of Enamel

2005 ◽  
Vol 874 ◽  
Author(s):  
Fuzhai Cui ◽  
Jun Ge ◽  
Xiumei Wang
Keyword(s):  
Mechanical Properties ◽  
Third Molar ◽  
Close Relation ◽  
Unique Property ◽  
Force Microscopy ◽  
The Past ◽  
Quantitative Measurements ◽  
Atomic Force ◽  
Synthetic Materials ◽  
Enamel Prism

AbstractEnamel is made up of enamel prisms separated by thin layer of organic sheaths. The mechanical properties of the prisms and the organic sheaths are obviously different from each other due to different compositions and microstructures. However, quantitative measurements of such differences have been a challenge in the past. The objective of this study is to accurately study the mechanical properties in the isolated domains within single enamel prism. The technique of nanoindentation combined with Atomic Force Microscopy (AFM) was employed to test the enamel specimens from mature human maxillary third molar. It was revealed that the nanohardness and elastic modulus of the sheaths were about 73.6% and 52.7% lower than those of the prisms. AFM topographies of the residual indent impressions also visually confirmed the differences. In addition to nanoindentation tests, the microstructures of enamel were carefully investigated in terms of hierarchical levels of organization to understand the structural reasons of the mechanical differences. We found a close relation between the variations of mechanical properties of enamel and its hierarchical structure. The analysis of the mechanical properties within enamel upon hierarchy is not only helpful to understand its unique property, but may also inspire ideas for the design of novel synthetic materials.

X-ray Gabor holography

1995 ◽  
Vol 53 ◽  
pp. 612-613
Author(s):  
Steve Lindaas ◽  
Chris Jacobsen ◽  
Alex Kalinovsky ◽  
Malcolm Howells
Keyword(s):  
Surface Relief ◽  
Biological Imaging ◽  
Specimen Preparation ◽  
X Rays ◽  
X Ray ◽  
Water Window ◽  
Biological Objects ◽  
Transmission Imaging ◽  
Atomic Force ◽  
Electron Microscopes

Soft x-ray microscopy offers an approach to transmission imaging of wet, micron-thick biological objects at a resolution superior to that of optical microscopes and with less specimen preparation/manipulation than electron microscopes. Gabor holography has unique characteristics which make it particularly well suited for certain investigations: it requires no prefocussing, it is compatible with flash x-ray sources, and it is able to use the whole footprint of multimode sources. Our method serves to refine this technique in anticipation of the development of suitable flash sources (such as x-ray lasers) and to develop cryo capabilities with which to reduce specimen damage. Our primary emphasis has been on biological imaging so we use x-rays in the water window (between the Oxygen-K and Carbon-K absorption edges) with which we record holograms in vacuum or in air.The hologram is recorded on a high resolution recording medium; our work employs the photoresist poly(methylmethacrylate) (PMMA). Following resist “development” (solvent etching), a surface relief pattern is produced which an atomic force microscope is aptly suited to image.

The Contribution of Intermediate-Voltage, High-Resolution Electron Microscopy In Materials Science: An Appraisal

1990 ◽  
Vol 48 (1) ◽  
pp. 478-479
Author(s):  
John L. Hutchison
Keyword(s):  
High Resolution ◽  
Materials Science ◽  
High Resolution Electron Microscopy ◽  
Optical Diffraction ◽  
The Past ◽  
Resolution Electron ◽  
Extreme Sensitivity ◽  
Electron Microscopes ◽  
New Generation ◽  
Small Metal Particles

Over the past five years or so the development of a new generation of high resolution electron microscopes operating routinely in the 300-400 kilovolt range has produced a dramatic increase in resolution, to around 1.6 Å for “structure resolution” and approaching 1.2 Å for information limits. With a large number of such instruments now in operation it is timely to assess their impact in the various areas of materials science where they are now being used. Are they falling short of the early expectations? Generally, the manufacturers’ claims regarding resolution are being met, but one unexpected factor which has emerged is the extreme sensitivity of these instruments to both floor-borne and acoustic vibrations. Successful measures to counteract these disturbances may require the use of special anti-vibration blocks, or even simple oil-filled dampers together with springs, with heavy curtaining around the microscope room to reduce noise levels. In assessing performance levels, optical diffraction analysis is becoming the accepted method, with rotational averaging useful for obtaining a good measure of information limits. It is worth noting here that microscope alignment becomes very critical for the highest resolution.In attempting an appraisal of the contributions of intermediate voltage HREMs to materials science we will outline a few of the areas where they are most widely used. These include semiconductors, oxides, and small metal particles, in addition to metals and minerals.

Methodology of studying the mechanical properties of composite materials (reinforced concrete)

2018 ◽  
Vol 84 (12) ◽  
pp. 61-67
Author(s):  
V. A. Eryshev
Keyword(s):  
Mechanical Properties ◽  
Reinforced Concrete ◽  
Experimental Studies ◽  
Analytical Relationship ◽  
Hardened Concrete ◽  
Deformation Model ◽  
Joint Work ◽  
Concrete Shrinkage ◽  
Axial Tension ◽  
Tension And Compression

The mechanical properties of a complex composite material formed by steel and hardened concrete, are studied. A technique of operative quality control of new credible concrete and reinforcement, both in laboratory and field conditions is developed for determination of the strength and strain characteristics of materials, as well as cohesion forces determining their joint operation under load. The design of the mobile unit is presented. The unit provides a possibility of changing the direction of loading and testing the reinforced element of the given shape both for tension and compression. Moreover, the nomenclature of testing equipment and the number of molds for manufacturing concrete samples substantially decrease. Using the values of forcing resulting in concrete cracking when the joint work of concrete and reinforcement is disrupted the values of the inherent stresses and strains attributed to the concrete shrinkage are determined. An analytical relationship between the forces and deformations of the reinforced concrete sample with central reinforcement is derived for axial tension and compression, with allowance for strains and stresses in the reinforcement and concrete resulted from concrete shrinkage. The results of experimental studies are presented, including tension diagrams and diagrams of developing axial deformations with an increase in the load under the central loading of the reinforced elements. A methodology of accounting for stresses and deformations resulted from concrete shrinkage is developed. The applicability of the derived analytical relationships between stresses and deformations on the material diagrams to calculations of the reinforced concrete structures in the framework of the deformation model is estimated.

Recognition Pattern, Functional Mechanism and Application of Chitin and Chitosan Oligosaccharides in Sustainable Agriculture

2020 ◽  
Vol 26 (29) ◽  
pp. 3508-3521 ◽  
Author(s):  
Xiaochen Jia ◽  
Mijanur R. Rajib ◽  
Heng Yin
Keyword(s):  
Agricultural Production ◽  
Growth And Yield ◽  
Biotic Stresses ◽  
The Past ◽  
Chitosan Oligosaccharides ◽  
Recognition Pattern ◽  
Functional Mechanism ◽  
Chitin And Chitosan ◽  
And Storage ◽  
Further Development

Background: Application of chitin attracts much attention in the past decades as the second abundant polysaccharides in the world after cellulose. Chitin oligosaccharides (CTOS) and its deacetylated derivative chitosan oligosaccharides (COS) were shown great potentiality in agriculture by enhancing plant resistance to abiotic or biotic stresses, promoting plant growth and yield, improving fruits quality and storage, etc. Those applications have already served huge economic and social benefits for many years. However, the recognition mode and functional mechanism of CTOS and COS on plants have gradually revealed just in recent years. Objective: Recognition pattern and functional mechanism of CTOS and COS in plant together with application status of COS in agricultural production will be well described in this review. By which we wish to promote further development and application of CTOS and COS–related products in the field.

Investigating hollow corundum microspheres exfoliation of the elastomeric matrix

2019 ◽  
pp. 135-142
Author(s):  
N. V. Shadrinov ◽  
U. V. Evseeva
Keyword(s):  
Mechanical Properties ◽  
Atomic Force Microscope ◽  
Butadiene Rubber ◽  
Nitrile Butadiene Rubber ◽  
Elastomeric Matrix ◽  
Atomic Force

The results of study of the influence of hollow corundum microspheres HCM-S (5–100 µm) and HCM-L (70–180 µm) on the properties of nitrile butadiene rubber BNKS-18 are presented. The dependence of elastomer resistance to abrasion impact and physic and mechanical properties on the dispersion and concentration of hollow corundum microspheres is shown. The process of hollow corundum microspheres exfoliation of the elastomeric matrix, which largely determines the change of physic and mechanical properties, has been studied by specially developed stretching device compatible with an atomic force microscope. The paper describes microspheres exfoliation which is conventionally divided into 3 stages.

Mechanical Properties of Membrane Surface of Cultured Astrocyte Revealed by Atomic Force Microscopy

2000 ◽  
Vol 39 (Part 1, No. 6B) ◽  
pp. 3711-3716 ◽  
Author(s):  
Hatsuki Shiga ◽  
Yukako Yamane ◽  
Etsuro Ito ◽  
Kazuhiro Abe ◽  
Kazushige Kawabata ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Atomic Force Microscopy ◽  
Membrane Surface ◽  
Force Microscopy ◽  
Atomic Force
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