scholarly journals A method for determining the local mechanical properties using nanoindentation in oscillating mode

2020 ◽  
pp. 39-47
Author(s):  
R. I. Izyumov ◽  
◽  
A. Yu. Belyaev ◽  
A. L. Svistkov ◽  
◽  
...  
Keyword(s):  
Elastic Beam ◽  
Harmonic Signal ◽  
Force Microscopy ◽  
Atomic Force ◽  
Dependent Behavior ◽  
Local Properties ◽  
High Degree ◽  
Probe Material ◽  
Material Interaction ◽  
Oscillating Mode

A new method of processing of data obtained using atomic force microscopy (AFM) in the oscil-lating nanoindentation mode is proposed. The model of the AFM probe on elastic beam (canti-lever) interaction with a sample is developed. In addition to the static load, applied on a base of the cantilever, a force modulation, according to a harmonic law, is set. This approach makes possible to take into account not only the force of the probe-material interaction but also the phase shift of the cantilever oscillations with respect to a given harmonic signal on the cantilever base as well as the amplitudes ratio of these oscillations. This information allows the presence of the viscosity in the material evaluating. The advantage of the oscillatory regime over quasistatic indentation was shown. It consists in the possibility to exclude the influence of irreversible pro-cesses (plastic, brittle fracture in the material) on the result of the experiment and to reveal the presence of the time dependent behavior. It is shown that the model contains a small amount of constants; methods for their determination are proposed. The calculations, performed using the developed model, made it possible to make a number of recommendations on choosing the can-tilever stiffness to obtain the most informative experimental results. This approach seems per-spective in studying materials with a high degree of stiffness inhomogeneity, including the deter-mination of the local properties of filled nanocomposites near filler particles.

scholarly journals The effect of replacing iron atoms instead of zinc of the quaternary compound CZTS

2021 ◽  
Vol 2114 (1) ◽  
pp. 012033
Author(s):  
Abubaker.S. Mohammed
Keyword(s):  
Full Width Half Maximum ◽  
Energy Gap ◽  
Film Surface ◽  
X Ray Diffraction ◽  
Quaternary Compound ◽  
Force Microscopy ◽  
Atomic Force ◽  
Coating Method ◽  
Degree Of Crystallization ◽  
High Degree

Abstract In this article, the quaternary compound Cu2MSnS4 was prepared in a simple and inexpensive approach, where M is the iron (Fe) and zinc (Zn) atoms by the spin coating method on a glass substrate at room temperature (RT), as a result of replacing Zn atoms by Fe. Quaternary Cu2ZnSnS4 (CZTS) and Cu2FeSrS4 (CFTS) structural and optical properties have been studied successfully. The material has been identified by X-ray diffraction, and it was discovered that CZTS has a polycrystalline Tetragonal (kesterite) structure, whereas CFTS has a Tetragonal (stannite) structure. A reduction in the full width half maximum (FWHM) of the preferred plane implies a high degree of crystallization. The structural properties of the film surface, such as grain size and roughness, were studied by Atomic force microscopy (AFM). The results explain an increase in nanoparticle size and surface roughness when Fe is substituted by Zn in the CZTS structure. The absorption coefficient values of all designed compounds in visible regions are greater than 104/cm, and the results show that the absorbance coefficient increases with Fe add. The CZTS films showed an energy gap of 1.88 eV, and this value became 1.69 eV with substituted Fe instead of Zn.

Characteristics of Electron Transport Study of Composited Graphene-Zinc Oxide Thin Film Photoanode for Dye-Sensitized Solar Cells

2020 ◽  
Vol 307 ◽  
pp. 185-191
Author(s):  
Noor Syafiqah Samsi ◽  
N.A.S. Affendi ◽  
M.K. Yaakob ◽  
M.F.M. Taib ◽  
A. Lepit ◽  
...  
Keyword(s):  
Zinc Oxide ◽  
Dye Sensitized Solar Cells ◽  
Xrd Analysis ◽  
Oxide Thin Film ◽  
X Ray Diffraction ◽  
Force Microscopy ◽  
Atomic Force ◽  
Zno Nanosheets ◽  
High Degree ◽  
Sensitized Solar Cells

Graphene-Zinc Oxide (Gr-ZnO) nanocomposites films were successfully synthesized via facile electrodeposition method in an aqueous solution under Gr concentration conditions. Gr, as a highly conductive carbon, acts as an anchor for ZnO nanosheets and plays a substantial role in controlling the degree of dispersion of ZnO nanosheets onto indium-doped tin oxide (ITO) substrate to form Gr-ZnO nanocomposite. Atomic force microscopy (AFM) and field-emission scanning electron microscopy (FESEM) analysis of Gr-ZnO nanocomposite samples confirmed that the presence of ZnO nanosheets with a high degree of dispersity and crystallinity which is well linked to the thin layer of Gr nanoparticle on ITO substrate. The surface roughness of the films found increased to ~270 nm on Gr-ZnO as compared to Gr ~44 nm and ZnO ~3 nm. Further, the x-ray diffraction spectroscopy (XRD) analysis showed the result is in good agreement with Raman spectroscopy study. The cyclic voltammetry (CV) of Gr-ZnO nanocomposite revealed that the effect of electron-hole recombination process was increased and the presence of Gr in ZnO photoanode provides the fastest redox reaction and hence offers the fastest electron transfer in photoanode.

scholarly journals Optical and Morphological Studies of Thermally Evaporated PTCDI-C8 Thin Films for Organic Solar Cell Applications

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Ronak Rahimi ◽  
V. Narang ◽  
D. Korakakis
Keyword(s):  
Thin Films ◽  
Silicon Substrates ◽  
High Electron ◽  
Ambient Conditions ◽  
Force Microscopy ◽  
Morphological Studies ◽  
Atomic Force ◽  
Organic Semiconductor Devices ◽  
Thermal Evaporator ◽  
High Degree

PTCDI-C8 due to its relatively high photosensitivity and high electron mobility has attracted much attention in organic semiconductor devices. In this work, thin films of PTCDI-C8 with different thicknesses were deposited on silicon substrates with native silicon dioxide using a vacuum thermal evaporator. Several material characterization techniques have been utilized to evaluate the structure, morphology, and optical properties of these films. Their optical constants (refractive index and extinction coefficient) have been extracted from the spectroscopic ellipsometry (SE). X-ray reflectivity (XRR) and atomic force microscopy (AFM) were employed to determine the morphology and structure as well as the thickness and roughness of the PTCDI-C8 thin films. These films revealed a high degree of structural ordering within the layers. All the experimental measurements were performed under ambient conditions. PTCDI-C8 films have shown to endure ambient condition which allows pots-deposition characterization.

Novel vapor phase method for making ultra thin conformal films of polytetrafluoroethylene (PTFE)

2007 ◽  
Vol 992 ◽  
Author(s):  
Sushant Gupta ◽  
Arul Arjunan Chakkaravarthi ◽  
Rajiv Singh ◽  
Jeff Opalko ◽  
Deepika Singh
Keyword(s):  
Chemical Nature ◽  
Phase Method ◽  
Force Microscopy ◽  
Angle Measurements ◽  
Atomic Force ◽  
Contact Angle Measurements ◽  
Pulsed Electron Deposition ◽  
Afm Micrographs ◽  
High Degree ◽  
Deposition Conditions

AbstractUltra-thin conformal polytetrafluoroethylene (PTFE) films were prepared by a novel physical vapor technique i.e., pulsed electron deposition (PED) technique. Prepared PTFE or Teflon thin films show high degree of conformity on patterned substrates. Under optimized deposition conditions the films exhibit superhydrophobicity. The PED processed films were characterized using scanning electron microscopy (SEM) and atomic force microscopy (AFM) micrographs and the surface morphology and the conformal nature of the films were studied. The chemical nature and hydrophobicity were studied by FTIR and contact angle measurements, respectively.

scholarly journals Structural characterization of gephyrin by AFM and SAXS reveals a mixture of compact and extended states

2013 ◽  
Vol 69 (10) ◽  
pp. 2050-2060 ◽  
Author(s):  
Bodo Sander ◽  
Giancarlo Tria ◽  
Alexander V. Shkumatov ◽  
Eun-Young Kim ◽  
J. Günter Grossmann ◽  
...  
Keyword(s):  
Conformational Dynamics ◽  
Cd Spectroscopy ◽  
X Ray ◽  
Force Microscopy ◽  
X Ray Scattering ◽  
Atomic Force ◽  
Extended States ◽  
High Degree

Gephyrin is a trimeric protein involved in the final steps of molybdenum-cofactor (Moco) biosynthesis and in the clustering of inhibitory glycine and GABAAreceptors at postsynaptic specializations. Each protomer consists of stably folded domains (referred to as the G and E domains) located at either terminus and connected by a proteolytically sensitive linker of ∼150 residues. Both terminal domains can oligomerize in their isolated forms; however, in the context of the full-length protein only the G-domain trimer is permanently present, whereas E-domain dimerization is prevented. Atomic force microscopy (AFM) and small-angle X-ray scattering (SAXS) reveal a high degree of flexibility in the structure of gephyrin. The results imply an equilibrium between compact and extended conformational states in solution, with a preference for compact states. CD spectroscopy suggests that a partial compaction is achieved by interactions of the linker with the G and E domains. Taken together, the data provide a rationale for the role of the linker in the overall structure and the conformational dynamics of gephyrin.

Damage Precursors in Individual Microfibers

2016 ◽  
Author(s):  
Daniel P. Cole ◽  
Todd C. Henry ◽  
Frank Gardea ◽  
Robert Haynes
Keyword(s):  
Early Stage ◽  
Force Microscopy ◽  
Atomic Force ◽  
Local Material ◽  
Before And After ◽  
The Matrix ◽  
Local Properties ◽  
Damage Precursor ◽  
The Individual ◽  
Multiscale Composites

Structural health monitoring of composite materials is limited by the lack of fundamental understanding of early stage damage at the local material level. This includes damage precursor formation on fiber surfaces, within the matrix, and at the fiber-matrix interface/interphase. In this effort, we present a micro-/nano-scale technique for characterizing damage precursor formation on individual carbon fibers exposed to cyclic tensile loads. Nanoindentation and atomic force microscopy (AFM) were used to study the local properties of the individual microfibers before and after global loading events. An AFM image analysis was used to track evolution of topography on the fiber surfaces. The work is a first step toward understanding damage precursor formation in individual microfibers; the work is expected to enable multiscale composites modeling efforts as well as enable the development of future self-sensing materials.

Assembly and organization of the N-terminal region of mucin MUC5AC: Indications for structural and functional distinction from MUC5B

2021 ◽  
Vol 118 (39) ◽  
pp. e2104490118
Author(s):  
Jerome Carpenter ◽  
Yang Wang ◽  
Richa Gupta ◽  
Yuanli Li ◽  
Prashamsha Haridass ◽  
...  
Keyword(s):  
Lung Diseases ◽  
Higher Order ◽  
Chronic Obstructive ◽  
Microscopy Imaging ◽  
Obstructive Lung Diseases ◽  
Force Microscopy ◽  
Macromolecular Assembly ◽  
Atomic Force ◽  
Chronic Obstructive Lung Diseases ◽  
High Degree

Elevated levels of MUC5AC, one of the major gel-forming mucins in the lungs, are closely associated with chronic obstructive lung diseases such as chronic bronchitis and asthma. It is not known, however, how the structure and/or gel-making properties of MUC5AC contribute to innate lung defense in health and drive the formation of stagnant mucus in disease. To understand this, here we studied the biophysical properties and macromolecular assembly of MUC5AC compared to MUC5B. To study each native mucin, we used Calu3 monomucin cultures that produced MUC5AC or MUC5B. To understand the macromolecular assembly of MUC5AC through N-terminal oligomerization, we expressed a recombinant whole N-terminal domain (5ACNT). Scanning electron microscopy and atomic force microscopy imaging indicated that the two mucins formed distinct networks on epithelial and experimental surfaces; MUC5B formed linear, infrequently branched multimers, whereas MUC5AC formed tightly organized networks with a high degree of branching. Quartz crystal microbalance-dissipation monitoring experiments indicated that MUC5AC bound significantly more to hydrophobic surfaces and was stiffer and more viscoelastic as compared to MUC5B. Light scattering analysis determined that 5ACNT primarily forms disulfide-linked covalent dimers and higher-order oligomers (i.e., trimers and tetramers). Selective proteolytic digestion of the central glycosylated region of the full-length molecule confirmed that MUC5AC forms dimers and higher-order oligomers through its N terminus. Collectively, the distinct N-terminal organization of MUC5AC may explain the more adhesive and unique viscoelastic properties of branched, highly networked MUC5AC gels. These properties may generate insight into why/how MUC5AC forms a static, “tethered” mucus layer in chronic muco-obstructive lung diseases.

scholarly journals In vitro Performance of Nano-heterogeneous Dentin Adhesive

2008 ◽  
Vol 87 (9) ◽  
pp. 829-833 ◽  
Author(s):  
Q. Ye ◽  
J.G. Park ◽  
E. Topp ◽  
Y. Wang ◽  
A. Misra ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Phase Image ◽  
Force Microscopy ◽  
Dental Tissues ◽  
Atomic Force ◽  
Dentin Adhesives ◽  
Mechanical Durability ◽  
Nanophase Separation ◽  
High Degree

Water is ubiquitous in the mouths of healthy individuals and routinely interferes with efforts to bond restorations to dental tissues. Our previous studies using tapping-mode atomic force microscopy (TMAFM) have shown that nanophase separation is a general feature of cross-linked polymethacrylates photocured in the presence of water. To explore the relationship between nanophase separation in dentin adhesives and their long-term mechanical properties, we evaluated model adhesives after 3 months of aqueous storage. The degree of contrast in the TMAFM phase image depended on the formulations used, ranging from ‘not observable’ to ‘very strong’. Correspondingly, the mechanical properties of these model adhesives varied from ‘minimal change’ to ‘significant depreciation’. The results support the hypothesis that a high degree of heterogeneity at the nano-scale is associated with poor mechanical durability in these model adhesives.

scholarly journals Material discrimination and mixture ratio estimation in nanocomposites via harmonic atomic force microscopy

2017 ◽  
Vol 8 ◽  
pp. 2771-2780 ◽  
Author(s):  
Weijie Zhang ◽  
Yuhang Chen ◽  
Xicheng Xia ◽  
Jiaru Chu
Keyword(s):  
Atomic Force Microscopy ◽  
Harmonic Signal ◽  
Laser Spot ◽  
Harmonic Amplitude ◽  
Mixture Ratio ◽  
Force Microscopy ◽  
Drive Frequency ◽  
Atomic Force ◽  
Potential Applications ◽  
Feedback Set

Harmonic atomic force microscopy (AFM) was employed to discriminate between different materials and to estimate the mixture ratio of the constituent components in nanocomposites. The major influencing factors, namely amplitude feedback set-point, drive frequency and laser spot position along the cantilever beam, were systematically investigated. Employing different set-points induces alternation of tip–sample interaction forces and thus different harmonic responses. The numerical simulations of the cantilever dynamics were well-correlated with the experimental observations. Owing to the deviation of the drive frequency from the fundamental resonance, harmonic amplitude contrast reversal may occur. It was also found that the laser spot position affects the harmonic signal strengths as expected. Based on these investigations, harmonic AFM was employed to identify material components and estimate the mixture ratio in multicomponent materials. The composite samples are composed of different kinds of nanoparticles with almost the same shape and size. Higher harmonic imaging offers better information on the distribution and mixture of different nanoparticles as compared to other techniques, including topography and conventional tapping phase. Therefore, harmonic AFM has potential applications in various fields of nanoscience and nanotechnology.

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