scholarly journals Nanomechanical and Nanotribological Properties of Nanostructured Coatings of Tantalum and Its Compounds on Steel Substrates

Nanomaterials ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 2407
Author(s):  
Galina Melnikova ◽  
Tatyana Kuznetsova ◽  
Vasilina Lapitskaya ◽  
Agata Petrovskaya ◽  
Sergei Chizhik ◽  
...  
Keyword(s):  
Elastic Modulus ◽  
Tantalum Nitride ◽  
Volumetric Wear ◽  
Nanostructured Films ◽  
Force Microscopy ◽  
Atomic Force ◽  
Tantalum Films ◽  
Direct Current Magnetron Sputtering ◽  
The Coefficient Of Friction ◽  
Steel Substrates

The present paper addresses the problem of identification of microstructural, nanomechanical, and tribological properties of thin films of tantalum (Ta) and its compounds deposited on stainless steel substrates by direct current magnetron sputtering. The compositions of the obtained nanostructured films were determined by energy dispersive spectroscopy. Surface morphology was investigated using atomic force microscopy (AFM). The coatings were found to be homogeneous and have low roughness values (<10 nm). The values of microhardness and elastic modulus were obtained by means of nanoindentation. Elastic modulus values for all the coatings remained unchanged with different atomic percentage of tantalum in the films. The values of microhardness of the tantalum films were increased after incorporation of the oxygen and nitrogen atoms into the crystal lattice of the coatings. The coefficient of friction, CoF, was determined by the AFM method in the “sliding” and “plowing” modes. Deposition of the coatings on the substrates led to a decrease of CoF for the coating-substrate system compared to the substrates; thus, the final product utilizing such a coating will presumably have a longer service life. The tantalum nitride films were characterized by the smallest values of CoF and specific volumetric wear.

scholarly journals A Universal Model for the Log-Normal Distribution of Elasticity in Polymeric Gels and Its Relevance to Mechanical Signature of Biological Tissues

Biology ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 64
Author(s):  
Arnaud Millet
Keyword(s):  
Elastic Modulus ◽  
Normal Distribution ◽  
Biological Tissues ◽  
Force Microscopy ◽  
Polymeric Gels ◽  
Atomic Force ◽  
Clear Explanation ◽  
Log Normal ◽  
Log Normal Distribution

The mechanosensitivity of cells has recently been identified as a process that could greatly influence a cell’s fate. To understand the interaction between cells and their surrounding extracellular matrix, the characterization of the mechanical properties of natural polymeric gels is needed. Atomic force microscopy (AFM) is one of the leading tools used to characterize mechanically biological tissues. It appears that the elasticity (elastic modulus) values obtained by AFM presents a log-normal distribution. Despite its ubiquity, the log-normal distribution concerning the elastic modulus of biological tissues does not have a clear explanation. In this paper, we propose a physical mechanism based on the weak universality of critical exponents in the percolation process leading to gelation. Following this, we discuss the relevance of this model for mechanical signatures of biological tissues.

Micro/Nano-Tribological Behavior of Octadecyltrichlorosilane on Silicon as a Coating for MEMS

2005 ◽  
Author(s):  
J. Barriga ◽  
B. Ferna´ndez ◽  
E. Abad ◽  
B. Coto
Keyword(s):  
Liquid Phase ◽  
Vapour Phase ◽  
Stick Slip ◽  
Force Microscopy ◽  
Angle Measurements ◽  
Atomic Force ◽  
Contact Angle Measurements ◽  
Assembled Monolayers ◽  
The Coefficient Of Friction ◽  
Semicontact Mode

Despite progresses achieved in the technology of MEMS, the tribological problem continues being an unresolved matter. Wear and stick-slip phenomena are many times the origin of failure of these devices. The application of self-assembled monolayers (SAMs) in liquid phase seems to be a solution to this problems. SAMs of octadecyltrichlorosilane (CH3(CH2)17SiCl3, OTS) were attached to Si(100) oxidized in liquid phase. Contact angle measurements were used for characterizing the grade of hydrophobicity. The topography of the coating was obtained with an Atomic Force Microscopy (AFM) in semicontact mode. The images showed the presence of particles related to the polymerization of the precursor molecule during the formation process of the SAMs. Creating the film of lubricant in vapour phase would avoid this undesirable effect. Tribological tests were carried out with a microtribometer in linear reciprocating movement with a ball of 2 mm of diameter (100Cr6 and Si3N4) and load of some milinewtons. Results were compared with those obtained for silicon oxidized without any coating. The coefficient of friction (COF) and wear (substrate and ball) were studied under different test conditions.

Preparation and Research on the Lateral Elastic Modulus of the MnO2 Nanowires

2013 ◽  
Vol 662 ◽  
pp. 84-87
Author(s):  
Yong Jiang ◽  
Jian Cheng Deng ◽  
Yan Huai Ding ◽  
Jiu Ren Yin ◽  
Ping Zhang
Keyword(s):  
Elastic Modulus ◽  
Crystal Form ◽  
Bending Test ◽  
X Ray Diffraction ◽  
Nanowire Diameter ◽  
X Ray ◽  
Three Point Bending ◽  
Force Microscopy ◽  
Atomic Force ◽  
Mno2 Nanowires

MnO2 nanowires with large aspect ratio were successfully synthesized via a hydrothermal method. In this method, Mn(NO3)2 was as a source of manganese and NH4NO3 as an oxidant. The structure and morphology of the MnO2 nanowires were characterized by X ray diffraction (XRD) and scanning electron microscope (SEM). Their lateral elastic modulus was characterized via a nanoscale three-point bending test by atomic force microscopy (AFM) equipped with picoforce. The results indicate that the crystal form of MnO2 was β-MnO2. The elastic modulus of the nanowires decreased with the increase in nanowire diameter. This elastic modulus was in the range of 33.36-77.84GPa as the diameter ranged from 240 to 185nm.

Elastic Modulus of Single Cellulose Microfibrils from Tunicate Measured by Atomic Force Microscopy

2009 ◽  
Vol 10 (9) ◽  
pp. 2571-2576 ◽  
Author(s):  
Shinichiro Iwamoto ◽  
Weihua Kai ◽  
Akira Isogai ◽  
Tadahisa Iwata
Keyword(s):  
Atomic Force Microscopy ◽  
Elastic Modulus ◽  
Cellulose Microfibrils ◽  
Force Microscopy ◽  
Atomic Force

Quantitative mechanical analysis of indentations on layered, soft elastic materials

Soft Matter ◽  
2019 ◽  
Vol 15 (8) ◽  
pp. 1776-1784 ◽  
Author(s):  
Bryant L. Doss ◽  
Kiarash Rahmani Eliato ◽  
Keng-hui Lin ◽  
Robert Ros
Keyword(s):  
Atomic Force Microscopy ◽  
Elastic Modulus ◽  
Cell Mechanics ◽  
Biological Samples ◽  
Mechanical Analysis ◽  
Elastic Materials ◽  
Mechanical Heterogeneity ◽  
Popular Method ◽  
Force Microscopy ◽  
Atomic Force

Atomic force microscopy (AFM) is becoming an increasingly popular method for studying cell mechanics, however the existing analysis tools for determining the elastic modulus from indentation experiments are unable to quantitatively account for mechanical heterogeneity commonly found in biological samples.

scholarly journals A Novel Toolkit for Characterizing the Mechanical and Electrical Properties of Engineered Neural Tissues

Biosensors ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 51 ◽  
Author(s):  
Meghan Robinson ◽  
Karolina Valente ◽  
Stephanie Willerth
Keyword(s):  
Elastic Modulus ◽  
Electrical Properties ◽  
Elastic Moduli ◽  
Direct Method ◽  
Hydrogel Scaffolds ◽  
Force Microscopy ◽  
Mechanical And Electrical Properties ◽  
Atomic Force ◽  
Neural Tissues ◽  
Electrical Signaling

We have designed and validated a set of robust and non-toxic protocols for directly evaluating the properties of engineered neural tissue. These protocols characterize the mechanical properties of engineered neural tissues and measure their electrophysical activity. The protocols obtain elastic moduli of very soft fibrin hydrogel scaffolds and voltage readings from motor neuron cultures. Neurons require soft substrates to differentiate and mature, however measuring the elastic moduli of soft substrates remains difficult to accurately measure using standard protocols such as atomic force microscopy or shear rheology. Here we validate a direct method for acquiring elastic modulus of fibrin using a modified Hertz model for thin films. In this method, spherical indenters are positioned on top of the fibrin samples, generating an indentation depth that is then correlated with elastic modulus. Neurons function by transmitting electrical signals to one another and being able to assess the development of electrical signaling serves is an important verification step when engineering neural tissues. We then validated a protocol wherein the electrical activity of motor neural cultures is measured directly by a voltage sensitive dye and a microplate reader without causing damage to the cells. These protocols provide a non-destructive method for characterizing the mechanical and electrical properties of living spinal cord tissues using novel biosensing methods.

scholarly journals An investigation of surface properties, local elastic modulus and interaction with simulated pulmonary surfactant of surface modified inhalable voriconazole dry powders using atomic force microscopy

RSC Advances ◽  
2016 ◽  
Vol 6 (31) ◽  
pp. 25789-25798 ◽  
Author(s):  
Sumit Arora ◽  
Michael Kappl ◽  
Mehra Haghi ◽  
Paul M. Young ◽  
Daniela Traini ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Elastic Modulus ◽  
Surface Properties ◽  
Pulmonary Surfactant ◽  
Dry Powders ◽  
Force Microscopy ◽  
Atomic Force ◽  
Surface Modified ◽  
Spray Dried

l-Leucine modified voriconazole spray dried micropartcles.

scholarly journals Mechanical Characterization of a Dynamic and Tunable Methacrylated Hyaluronic Acid Hydrogel

2016 ◽  
Vol 138 (2) ◽  
Author(s):  
Matthew G. Ondeck ◽  
Adam J. Engler
Keyword(s):  
Hyaluronic Acid ◽  
Elastic Modulus ◽  
Monomer Concentration ◽  
Degree Of Polymerization ◽  
Force Microscopy ◽  
3T3 Fibroblasts ◽  
Atomic Force ◽  
Spread Area ◽  
Nih 3T3

Hyaluronic acid (HA) is a commonly used natural polymer for cell scaffolding. Modification by methacrylate allows it to be polymerized by free radicals via addition of an initiator, e.g., light-sensitive Irgacure, to form a methacrylated hyaluronic acid (MeHA) hydrogel. Light-activated crosslinking can be used to control the degree of polymerization, and sequential polymerization steps allow cells plated onto or in the hydrogel to initially feel a soft and then a stiff matrix. Here, the elastic modulus of MeHA hydrogels was systematically analyzed by atomic force microscopy (AFM) for a number of variables including duration of UV exposure, monomer concentration, and methacrylate functionalization. To determine how cells would respond to a specific two-step polymerization, NIH 3T3 fibroblasts were cultured on the stiffening MeHA hydrogels and found to reorganize their cytoskeleton and spread area upon hydrogel stiffening, consistent with cells originally cultured on substrates of the final elastic modulus.

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