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Qing Li, Chao Wang, Biao Han, Feini Qu, Hao Qi, Christopher Y Li, Robert L Mauck, Lin Han
To elucidate how maturation impacts the structure and mechanics of meniscus extracellular matrix (ECM) at the length scale of collagen fibrils and fibers, we tested the micromechanical properties of fetal and adult bovine menisci via atomic force microscopy (AFM)-nanoindentation. For circumferential fibers, we detected significant increase in the effective indentation modulus, Eind , with age. Such impact is in agreement with the increase in collagen fibril diameter and alignment during maturation, and is more pronounced in the outer zone, where collagen fibrils are more aligned and packed...
March 9, 2018: Journal of Biomechanics
Orestis G Andriotis, Sylvia Desissaire, Philipp J Thurner
Tissue hydration is well known to influence tissue mechanics and can be tuned via osmotic pressure. Collagen fibrils are nature's nanoscale building blocks to achieve biomechanical function in a broad range of biological tissues and across many species. Intrafibrillar covalent cross-links have long been thought to play pivotal role for collagen fibril elasticity, but predominantly at large, far from physiological, strains. Performing nanotensile experiments of collagen fibrils at varying hydration levels by adjusting osmotic pressure in situ during atomic force microscopy experiments, we show the power the intrafibrillar non-covalent interactions have for defining collagen fibril tensile elasticity at low fibril strains...
March 12, 2018: ACS Nano
Mamat-Noorhidayah, Kenjiro Yazawa, Keiji Numata, Y Norma-Rashid
Resilin functions as an elastic spring that demonstrates extraordinary extensibility and elasticity. Here we use combined techniques, laser scanning confocal microscopy (LSCM) and scanning electron microscopy (SEM) to illuminate the structure and study the function of wing flexibility in damselflies, focusing on the genus Rhinocypha. Morphological studies using LSCM and SEM revealed that resilin patches and cuticular spikes were widespread along the longitudinal veins on both dorsal and ventral wing surfaces...
2018: PloS One
R Al-Obaidi, H Salehi, A Desoutter, L Bonnet, P Etienne, E Terrer, B Jacquot, B Levallois, H Tassery, F J G Cuisinier
White lesions represent an early phase of caries formation. 20 human sound premolars were subjected to pH cycling procedure to induce subsurface lesions (SLs) in vitro. In addition, 2 teeth with naturally developed white spot lesions (WSLs) were used as references. All specimens characterized by confocal Raman microscopy being used for the first time in examining white & subsurface lesions and providing a high resolution chemical and morphological map based on phosphate peak intensity alterations at 960 cm-1 ...
March 6, 2018: Scientific Reports
Ana Paula C A Beltrame, Dakota Suchyta, Islam Abd Alraheam, Anas Mohammed, Mark Schoenfisch, Ricardo Walter, Izabel C S Almeida, Liliete C Souza, Patricia A Miguez
The aim of this study was to evaluate the antierosive effect of phosphorylated chitosan in dentin. Bovine dentin specimens were randomly distributed into the following groups: (1) no treatment (NoTx/negative control), (2) phosphate-buffered saline solution (PBS), (3) AmF/NaF/SnCl2 (positive control), (4) 0.5% chitosan solution (Chi), (5) 0.5% neutral phosphorylated (NP)-Chi, and (6) 0.5% alkaline phosphorylated (AP)-Chi. The specimens were submitted to de-remineralization treatment cycles for 5 days: 0.5% citric acid (2 min), remineralizing solution (30 min), and surface treatment according to assigned groups (2 min, 6×/day)...
March 6, 2018: Caries Research
Daan Vorselen, Margherita Marchetti, Carmen López-Iglesias, Peter J Peters, Wouter H Roos, Gijs J L Wuite
Small multilamellar vesicles may have benefits over unilamellar vesicles for drug delivery, such as an increased volume for hydrophobic drugs. In addition, their altered mechanical properties might be beneficial for cellular uptake. Here, we show how atomic force microscopy (AFM) can be used to detect and characterize multilamellar vesicles. We quantify the size of each break event occurring during AFM nanoindentations, which shows good agreement with the thickness of supported lipid bilayers. Analyzing the size and number of these events for individual vesicles allows us to distinguish between vesicles consisting of 1 up to 5 bilayers...
March 5, 2018: Nanoscale
Shaoning Jiang, Zhiming Wang
The effect of post-irradiation annealing on the microstructures and mechanical properties of V-4Cr-4Ti alloys was studied. Helium-hydrogen-irradiated sequentially V-4Cr-4Ti alloys at room temperature (RT) were undergone post-irradiation annealing at 450 °C over periods of up to 30 h. These samples were carried out by high-resolution transmission electron microscopy (HRTEM) observation and nanoindentation test. With the holding time, large amounts of point defects produced during irradiation at RT accumulated into large dislocation loops and then dislocation nets which promoted the irradiation hardening...
March 2, 2018: Nanoscale Research Letters
Jose Mario Paiva, German Fox-Rabinovich, Edinei Locks Junior, Pietro Stolf, Yassmin Seid Ahmed, Marcelo Matos Martins, Carlos Bork, Stephen Veldhuis
In the aluminum die casting process, erosion, corrosion, soldering, and die sticking have a significant influence on tool life and product quality. A number of coatings such as TiN, CrN, and (Cr,Al)N deposited by physical vapor deposition (PVD) have been employed to act as protective coatings due to their high hardness and chemical stability. In this study, the wear performance of two nanocomposite AlTiN and AlCrN coatings with different structures were evaluated. These coatings were deposited on aluminum die casting mold tool substrates (AISI H13 hot work steel) by PVD using pulsed cathodic arc evaporation, equipped with three lateral arc-rotating cathodes (LARC) and one central rotating cathode (CERC)...
February 28, 2018: Materials
Zhenzhen Zhang, Jiawen Guo, Yali Sun, Beimin Tian, Xiaojuan Zheng, Ming Zhou, Lin He, Shaofeng Zhang
OBJECTIVES: The purpose of this study is to improve wear resistance and mechanical properties of lithium disilicate glass-ceramics by refining their crystal sizes. METHODS: After lithium disilicate glass-ceramics (LD) were melted to form precursory glass blocks, bar (N = 40, n = 10) and plate (N = 32, n = 8) specimens were prepared. According to the differential scanning calorimetry (DSC) of precursory glass, specimens G1-G4 were designed to form lithium disilicate glass-ceramics with different crystal sizes using a two-step thermal treatment...
February 20, 2018: Journal of the Mechanical Behavior of Biomedical Materials
Navdeep K Dhami, Abhijit Mukherjee, Elizabeth L J Watkin
Natural mineral formations are a window into important processes leading to carbon storage and mineralized carbonate structures formed through abiotic and biotic processes. In the current study, we made an attempt to undertake a comprehensive approach to characterize the mineralogical, mechanical, and microbial properties of different kinds of speleothems from karstic caves; with an aim to understand the bio-geo-chemical processes in speleothem structures and their impact on nanomechanical properties. We also investigated the biomineralization abilities of speleothem surface associated microbial communities in vitro ...
2018: Frontiers in Microbiology
Jiantuo Zhao, Jinyu Zhang, Zhaoqi Hou, Kai Wu, Xiaobin Feng, Gang Liu, Jun Sun
In order to achieve desired mechanical properties of alloys by manipulating grain boundaries via solute decoration, it is of great significance to understand the underlying mechanisms of microstructural evolution and plastic deformation. In this work, nanocrystalline Cu-W alloyed films with W concentrations spanning from 0 to 40 at. % were prepared by using magnetron sputtering. Thermal stability (within the temperature range of 200 °C - 600 °C) and hardness of the films were investigated by using the X-ray diffraction, transmission electron microscope (TEM) and nanoindentation, respectively...
February 22, 2018: Nanotechnology
Ernst Jan Bos, Mieke Pluemeekers, Marco Helder, Nikolay Kuzmin, Koen van der Laan, Marie-Louise Groot, Gerjo van Osch, Paul van Zuijlen
Background: In the human ear and nose, cartilage plays a key role in establishing its form and function. Interestingly, there is a noticeable paucity on biochemical, structural, and mechanical studies focused on facial cartilage. Such studies are needed to provide elementary knowledge that is fundamental to tissue engineering of cartilage. Therefore, in this study, a comparison is made of the biochemical, structural, and mechanical differences between ear, ala nasi, and septum on the extracellular matrix (ECM) level...
January 2018: Plastic and Reconstructive Surgery. Global Open
Antoine Guitton, Hana Kriaa, Emmanuel Bouzy, Julien Guyon, Nabila Maloufi
In this work, plastic deformation was locally introduced at room temperature by nanoindentation on a γ-TiAl-based alloy. Comprehensive analyses of microstructures were performed before and after deformation. In particular, the Burgers vectors, the line directions, and the mechanical twinning systems were studied via accurate electron channeling contrast imaging. Accommodation of the deformation are reported and a scenario is proposed. All features help to explain the poor ductility of the TiAl-based alloys at room temperature...
February 20, 2018: Materials
Sung-Yong Chun
Single-phase cubic (FCC) vanadium nitride (VN) coatings with different preferential orientations and residual stresses were obtained as a function of ICP power. Microstructural, crystallographic and mechanical characterizations were performed by FE-SEM, AFM, XRD and nanoindentation. The results show that ICP has significant effects on coating's microstructure, structural and mechanical properties of VN coatings. With an increase in ICP power, coating microstructure evolved from a porous columnar structure to a highly dense one...
March 1, 2018: Journal of Nanoscience and Nanotechnology
Sung-Yong Chun
Niobium nitride (NbN) films were deposited using asymmetric-bipolar pulsed dc sputtering at different pulse parameters. Microstructural, electrical and mechanical characterizations were performed by FE-SEM, AFM, LCR meter and nanoindentator. The results show that pulse frequency has significant effects on coating's microstructure, structural and electrical properties of NbN films. With an increase in pulse frequency, coating microstructure evolved from a porous columnar structure to a highly dense one. Average crystal grain sizes of NbN films were decreased from 52...
February 1, 2018: Journal of Nanoscience and Nanotechnology
W Streit Cunningham, Jonathan M Gentile, Osman El-Atwani, Chase N Taylor, Mert Efe, Stuart A Maloy, Jason R Trelewicz
The unique ability of grain boundaries to act as effective sinks for radiation damage plays a significant role in nanocrystalline materials due to their large interfacial area per unit volume. Leveraging this mechanism in the design of tungsten as a plasma-facing material provides a potential pathway for enhancing its radiation tolerance under fusion-relevant conditions. In this study, we explore the impact of defect microstructures on the mechanical behavior of helium ion implanted nanocrystalline tungsten through nanoindentation...
February 13, 2018: Scientific Reports
Nitesh Dhar Badgayan, Santosh Kumar Sahu, Sutanu Samanta, P S Rama Sreekanth
A thrust on improvement of different properties of polymer has taken a contemporary route with advent of nanofillers. Although several nanofillers are existent; MultiWalled Carbon Nanotubes- (MWCNTs) and h-Boron Nitride nanoplatelets-(h-BNNPs) unique combination of 1D and 2D dimensional geometry aids an advantage of B-C-N triad elemental effects on properties of tested samples. The current study aims to investigate the effects of MWCNT and h-BNNP reinforcement in High Density Polyethylene (HDPE) for high load bearing areas of medical applications requiring both elastic and viscous behavior...
February 2, 2018: Journal of the Mechanical Behavior of Biomedical Materials
Ramin Oftadeh, Brianne K Connizzo, Hadi Tavakoli Nia, Christine Ortiz, Alan J Grodzinsky
In this study, a poroviscoelastic finite element model (FEM) was developed and used in conjunction with an AFM-based wide-bandwidth nanorheology system to predict the frequency-dependent mechanical behavior of tendon and dermis subjected to compression via nanoindentation. The aim was to distinguish between loading rates that are dominated by either poroelasticity, viscoelasticity, or the superposition of these processes. Using spherical probe tips having different radii, the force and tip displacement were measured and the magnitude, |E∗|, and phase angle, ϕ, of the dynamic complex modulus were evaluated for mouse supraspinatus tendon and mouse dermis...
February 6, 2018: Acta Biomaterialia
Se Yeon Song, Min Soo Park, Jung Woo Lee, Ji Sun Yun
Silane coupling agents (SCAs) with different organofunctional groups were coated on the surfaces of Al₂O₃ ceramic particles through hydrolysis and condensation reactions, and the SCA-coated Al₂O₃ ceramic particles were dispersed in a commercial photopolymer based on interpenetrating networks (IPNs). The organofunctional groups that have high radical reactivity and are more effective in UV curing systems are usually functional groups based on acryl, such as acryloxy groups, methacrloxy groups, and acrylamide groups, and these silane coupling agents seem to improve interfacial adhesion and dispersion stability...
February 7, 2018: Nanomaterials
L Kurpaska, J Jasinski, E Wyszkowska, K Nowakowska-Langier, M Sitarz
In this study, structural and nanomechanical properties of zirconia polymorphs induced by ion irradiation were investigated by means of Raman spectroscopy and nanoindentation techniques. The zirconia layer have been produced by high temperature oxidation of pure zirconium at 600 °C for 5 h at normal atmospheric pressure. In order to distinguish between the internal and external parts of zirconia, the spherical metallographic sections have been prepared. The samples were irradiated at room temperature with 150 keV Ar+ ions at fluences ranging from 1 × 1015 to 1 × 1017 ions/cm2...
January 31, 2018: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
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