scholarly journals Preparation of a Fucoidan-Grafted Hyaluronan Composite Hydrogel for the Induction of Osteoblast Differentiation in Osteoblast-Like Cells

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1168
Author(s):  
Fu-Yin Hsu ◽  
Jheng-Jie Chen ◽  
Wen-Chieh Sung ◽  
Pai-An Hwang
Keyword(s):  
Mechanical Properties ◽  
Osteogenic Differentiation ◽  
Bone Substitute ◽  
1H Nmr Spectroscopy ◽  
Osteoblast Differentiation ◽  
Specific Activity ◽  
Brown Seaweed ◽  
Mg63 Cell ◽  
Flexible Structure ◽  
Hardness Values

A suitable bone substitute is necessary in bone regenerative medicine. Hyaluronan (HA) has excellent biocompatibility and biodegradability and is widely used in tissue engineering. Additionally, research on fucoidan (Fu), a fucose- and sulfate-rich polysaccharide from brown seaweed, for the promotion of bone osteogenic differentiation has increased exponentially. In this study, HA and Fu were functionalized by grafting methacrylic groups onto the backbone of the chain. Methacrylate-hyaluronan (MHA) and methacrylate-fucoidan (MFu) were characterized by FTIR and 1H NMR spectroscopy to confirm functionalization. The degrees of methacrylation (DMs) of MHA and MFu were 9.2% and 98.6%, respectively. Furthermore, we evaluated the mechanical properties of the hydrogels formed from mixtures of photo-crosslinkable MHA (1%) with varying concentrations of MFu (0%, 0.5%, and 1%). There were no changes in the hardness values of the hydrogels, but the elastic modulus decreased upon the addition of MFu, and these mechanical properties were not significantly different with or without preosteoblastic MG63 cell culture for up to 28 days. Furthermore, the cell morphologies and viabilities were not significantly different after culture with the MHA, MHA-MFu0.5, or MHA-MFu1.0 hydrogels, but the specific activity and mineralization of alkaline phosphatase (ALP) were significantly higher in the MHA-MFu1.0 hydrogel group compared to the other hydrogels. Hence, MHA-MFu composite hydrogels are potential bone graft materials that can provide a flexible structure and favorable niche for inducing bone osteogenic differentiation.

Micro-Hardness and Morphology of LDPE Influenced by Beta Radiation

2014 ◽  
Vol 606 ◽  
pp. 253-256 ◽  
Author(s):  
Martin Ovsik ◽  
Petr Kratky ◽  
David Manas ◽  
Miroslav Manas ◽  
Michal Stanek ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Hardness Test ◽  
Polymer Materials ◽  
Beta Radiation ◽  
Micro Hardness ◽  
X Ray Diffraction ◽  
Depth Sensing ◽  
Surface Layers ◽  
Hardness Values ◽  
Different Doses

This article deals with the influence of different doses of Beta radiation to the structure and mico-mechanical properties of Low-density polyethylene (LDPE). Hard surface layers of polymer materials, especially LDPE, can be formed by radiation cross-linking by β radiation with doses of 33, 66 and 99 kGy. Material properties created by β radiation are measured by micro-hardness test using the DSI method (Depth Sensing Indentation). Individual radiation doses caused structural and micro-mechanical changes which have a significant effect on the final properties of the LDPE tested. The highest values of micro-mechanical properties were reached at radiation dose of 66 and 99 kGy, when the micro-hardness values increased by about 21%. The changes were examined and confirmed by X-ray diffraction.

scholarly journals Involvement of the long noncoding RNA H19 in osteogenic differentiation and bone regeneration

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Zimo Zhou ◽  
Mohammad Showkat Hossain ◽  
Da Liu
Keyword(s):  
Bone Regeneration ◽  
Osteogenic Differentiation ◽  
Long Noncoding Rna ◽  
Noncoding Rna ◽  
Osteoblast Differentiation ◽  
Osteoclast Differentiation ◽  
Complex Processes ◽  
Osteogenic Induction ◽  
Novel Target

AbstractOsteogenic differentiation and bone regeneration are complex processes involving multiple genes and multiple steps. In this review, we summarize the effects of the long noncoding RNA (lncRNA) H19 on osteogenic differentiation.Osteogenic differentiation includes matrix secretion and calcium mineralization as hallmarks of osteoblast differentiation and the absorption of calcium and phosphorus as hallmarks of osteoclast differentiation. Mesenchymal stem cells (MSCs) form osteoprogenitor cells, pre-osteoblasts, mature osteoblasts, and osteocytes through induction and differentiation. lncRNAs regulate the expression of coding genes and play essential roles in osteogenic differentiation and bone regeneration. The lncRNA H19 is known to have vital roles in osteogenic induction.This review highlights the role of H19 as a novel target for osteogenic differentiation and the promotion of bone regeneration.

scholarly journals Experimental Evaluation of Mechanical Properties of Friction Welded Dissimilar Steels under Varying Axial Pressures

2016 ◽  
Vol 66 (1) ◽  
pp. 27-36 ◽  
Author(s):  
Amit Handa ◽  
Vikas Chawla
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Impact Strength ◽  
Failure Analysis ◽  
Friction Welding ◽  
Experimental Evaluation ◽  
Micro Hardness ◽  
Aisi 304 ◽  
Torsional Strength ◽  
Hardness Values

AbstractThe present study emphasizes on joints two industrially important materials AISI 304 with AISI 1021steels, produced by friction welding have been investigated. Samples were welded under different axial pressures ranging from 75MPa to 135MPa, at constant speed of 920rpm. The tensile strength, torsional strength, impact strength and micro hardness values of the weldments were determined and evaluated. Simultaneously the fractrography of the tensile tested specimens were carried out, so as to understand the failure analysis. It was observed that improved mechanical properties were noticed at higher axial pressures. Ductile failures of weldments were also observed at 120MPa and 135MPa axial pressures during fractography analysis.

scholarly journals Application of the plasticity characteristic determined by the indentation technique for evaluation of mechanical properties of coatings: I. specific features of the test method procedure

2004 ◽  
Vol 36 (1) ◽  
pp. 27-41 ◽  
Author(s):  
A.V. Byakova ◽  
Yu.V. Milman ◽  
A.A. Vlasov
Keyword(s):  
Mechanical Properties ◽  
Indentation Load ◽  
Test Method ◽  
Simplified Model ◽  
Micro Hardness ◽  
Properties Of Coatings ◽  
Modified Model ◽  
Plasticity Characteristic ◽  
Measurement Results ◽  
Hardness Values

Specific features of the test method procedure capable for determining the plasticity characteristic dH by indentation of inhomogeneous coatings affected by residual stress was clarified. When the value of the plasticity characteristic for coating was found to be as great as dH > 0.5 a simplified model was found to be reasonably adequate, while a modified model assumed compressibility of the deformation core beneath indentation. The advantage of the modified approach compared to the simplified one was grounded experimentally only if the elastic deformation for coating becomes greater than ?e ? 3.5%, resulting in the decrease of plasticity characteristic dH < 0.5. To overcome non accuracy caused by the effect of the scale factor on measurement results a comparison of different coatings was suggested using stabilized values of the plasticity characteristic dH determined under loads higher than critical, P ? Pc, ensuring week dependence of micro hardness values on the indentation load.

scholarly journals Properties of AlSi9Cu3 metal matrix micro and nano composites produced via stir casting

2018 ◽  
Vol 16 (1) ◽  
pp. 726-731 ◽  
Author(s):  
Tennur Gülşen Ünal ◽  
Ege Anıl Diler
Keyword(s):  
Mechanical Properties ◽  
Metal Matrix ◽  
Weight Fraction ◽  
Stir Casting ◽  
Mechanical Tests ◽  
Matrix Composites ◽  
Casting Method ◽  
Porosity Formation ◽  
Three Point Bending ◽  
Hardness Values

AbstractThe effects of micro and nano sized reinforcement particles on microstructure and mechanical properties of aluminium alloy-based metal matrix composites were investigated in this study. AlSi9Cu3 alloy was reinforced with micro and nano sized ceramic reinforcement particles at different weight fractions by using a stir casting method. The mechanical tests (hardness, three point bending) were performed to determine the mechanical properties of AlSi9Cu3 alloy-based microcomposites (AMMCs) and nanocomposites (AMMNCs). The experimental results have shown that the size and weight fraction of reinforcement particles have a strong influence on the microstructure and the mechanical properties of AlSi9Cu3 alloy-based microcomposites and nanocomposites. The relative densities of all AMMC and AMMNC samples are lower than unreinforced AlSi9Cu3 alloy due to porosity formation with the increase of weight fraction of reinforcement particles. As weight fraction increases, hardness values of AMMCs and AMMNCs increase. Maximum flexural strength can be obtained at 3.5wt.% for the AMMC sample with microsized Al2O3 particles and at 2wt.% for the AMMNC sample with nano-sized Al2O3 particles. After the weight fractions exceed these values, flexural strengths of both AMMCs and AMMNCs decrease due to clustering of Al2O3 particles.

scholarly journals Comparative Study of Two Nanoindentation Approaches for Assessing Mechanical Properties of Ion-Irradiated Stainless Steel 316

Metals ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 719 ◽  
Author(s):  
Michael Saleh ◽  
Zain Zaidi ◽  
Christopher Hurt ◽  
Mihail Ionescu ◽  
Paul Munroe ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Cross Section ◽  
Ion Irradiation ◽  
Thin Layers ◽  
Experimental Conditions ◽  
Irradiation Energy ◽  
Depth Analysis ◽  
Deformation Processes ◽  
Stainless Steel 316 ◽  
Hardness Values

Nanoindentation is a commonly used method to measure the hardness of surfaces with thin layers, and is especially useful in studying the change in mechanical properties of ion irradiated materials. This research compares two different methods of nanoindentation to study the changes in hardness resulting from ion irradiation of SS316 alloy. The samples were irradiated by He2+ ions at beam energies of 1, 2, and 3 MeV, respectively. The first method involves the indentation of the irradiated surface perpendicular to it using the continuous stiffness mode (CSM), while the second applies the indents on an oblique surface, accessing an inclined cross-section of the irradiated material. Finite element modelling has been used to further illuminate the deformation processes below the indents in the two methods. The hardness profiles obtained from the two nanoindentation methods reveal the differences in the outcomes and advantages of the respective procedures, and provide a useful guideline for their applicability to various experimental conditions. It is shown through an in depth analysis of the results that the ‘top-down’ method is preferable in the case when the ion irradiation energy, or, equivalently, the irradiated depth is small, due to its greater spatial resolution. However, the oblique cross section method is more suitable when the ion irradiation energy is >1 MeV, since it allows a more faithful measurement of hardness as a function of dose, as the plastic field is much smaller and more sensitive to local hardness values.

Effects of dynamic indentation on the mechanical response of materials

2008 ◽  
Vol 23 (6) ◽  
pp. 1604-1613 ◽  
Author(s):  
M.J. Cordill ◽  
N.R. Moody ◽  
W.W. Gerberich
Keyword(s):  
Thin Films ◽  
Mechanical Properties ◽  
Mechanical Response ◽  
Length Scale ◽  
Polycrystalline Nickel ◽  
Dynamic Indentation ◽  
Crystalline Materials ◽  
Fused Quartz ◽  
Hardness Values ◽  
Measured Hardness

Dynamic indentation techniques are often used to determine mechanical properties as a function of depth by continuously measuring the stiffness of a material. The dynamics are used by superimposing an oscillation on top of the monotonic loading. Of interest was how the oscillation affects the measured mechanical properties when compared to a quasi-static indent run at the same loading conditions as a dynamic. Single crystals of nickel and NaCl as well as a polycrystalline nickel sample and amorphous fused quartz and polycarbonate have all been studied. With respect to dynamic oscillations, the result is a decrease of the load at the same displacement and thus lower measured hardness values of the ductile crystalline materials. It has also been found that the first 100 nm of displacement are the most affected by the oscillating tip, an important length scale for testing thin films, nanopillars, and nanoparticles.

The Effect of Sub-Zero Treatment on Mechanical Properties of GTAW Welded AA6082

2016 ◽  
Vol 852 ◽  
pp. 349-354 ◽  
Author(s):  
R. Devanathan ◽  
Sanjivi Arul ◽  
T. Venkatamuni ◽  
D. Yuvarajan ◽  
D. Christopher Selvam
Keyword(s):  
Mechanical Properties ◽  
Arc Welding ◽  
Artificial Aging ◽  
Cryogenic Treatment ◽  
Welding Process ◽  
Travel Speed ◽  
Treatment Result ◽  
Gas Tungsten Arc ◽  
Shallow Cryogenic Treatment ◽  
Hardness Values

The consequence of sub-zero treatment on the mechanical properties of welded AA6082-T6 by Gas Tungsten Arc Welding (GTAW) which in turn softens the heat concentrated welded region owing to dissolution of the strengthening precipitates. The sub-zero i.e. Shallow Cryogenic Treatment (SCT) is carried out on GTAW welded plate having a thickness of 6 mm at -77°C by varying the electrode travel speed and sub-zero treatment periods. Welded region of AA6082 were tested for hardness and microstructure by adapting three different conditions such as welded, post weld artificial aging with and without sub-zero treatment. Result revealed that the amount of softening in the welded region is indirectly proportional to electrode travel speed during welding process. It is also observed that the post weld SCT with artificial aging has increased the micro hardness values on the welded region as a consequence of the reactivation in the sequence of precipitation.

scholarly journals Influence of Mo Additions on the Mechanical Properties of Cast Duplex Stainless Steels before and after Thermal Aging

Metals ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 295
Author(s):  
Shilei Li ◽  
Yanli Wang ◽  
Xitao Wang
Keyword(s):  
Mechanical Properties ◽  
Stainless Steels ◽  
Thermal Aging ◽  
Decomposition Kinetics ◽  
Before And After ◽  
Mo Content ◽  
Impact Energies ◽  
The Impact ◽  
Hardness Values ◽  
Mo Additions

The influence of Mo additions on the mechanical properties of cast duplex stainless steel (CDSS) before and after thermal aging was investigated using a series of model alloys with different Mo contents ranging from 0 to 1.75 wt%. By increasing Mo content, the content, morphology, and distribution of ferrite in CDSS change significantly. After thermal aging at 400 °C for 3000 h, the impact properties of all CDSS specimens obviously decline, and their hardness values in ferrite significantly increase. The impact energies of the aged CDSS decline, and the proportion of cleavage features significantly increases with Mo content increasing. The spinodal decomposition kinetics in ferrite is not significantly affected by the Mo contents. High content and interconnected ferrite will lead to the severe embrittlement in CDSS after thermal aging.

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