Mechanical and Biological Properties of Magnesium- and Silicon-Substituted Hydroxyapatite Scaffolds

Magnesium (Mg)- and silicon (Si)-substituted hydroxyapatite (HA) scaffolds were synthesized using the sponge replica method. The influence of Mg2+ and SiO44− ion substitution on the microstructural, mechanical and biological properties of HA scaffolds was evaluated. All synthesized scaffolds exhibited porosity >92%, with interconnected pores and pore sizes ranging between 200 and 800 μm. X-ray diffraction analysis showed that β-TCP was formed in the case of Mg substitution. X-ray fluorescence mapping showed a homogeneous distribution of Mg and Si ions in the respective scaffolds. Compared to the pure HA scaffold, a reduced grain size was observed in the Mg- and Si-substituted scaffolds, which greatly influenced the mechanical properties of the scaffolds. Mechanical tests revealed better performance in HA-Mg (0.44 ± 0.05 MPa), HA-Si (0.64 ± 0.02 MPa) and HA-MgSi (0.53 ± 0.01 MPa) samples compared to pure HA (0.2 ± 0.01 MPa). During biodegradability tests in Tris-HCl, slight weight loss and a substantial reduction in mechanical performances of the scaffolds were observed. Cell proliferation determined by the MTT assay using hBMSC showed that all scaffolds were biocompatible, and the HA-MgSi scaffold seemed the most effective for cell adhesion and proliferation. Furthermore, ALP activity and osteogenic marker expression analysis revealed the ability of HA-Si and HA-MgSi scaffolds to promote osteoblast differentiation.

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Multi-Scale Studies of 3D Printed Mn–Na–W/SiO2 Catalyst for Oxidative Coupling of Methane

Catalysts ◽

10.3390/catal11030290 ◽

2021 ◽

Vol 11 (3) ◽

pp. 290

Author(s):

Tim Karsten ◽

Vesna Middelkoop ◽

Dorota Matras ◽

Antonis Vamvakeros ◽

Stephen Poulston ◽

...

Keyword(s):

Oxidative Coupling ◽

Oxidative Coupling Of Methane ◽

Operating Conditions ◽

Homogeneous Distribution ◽

Silica Support ◽

X Ray Diffraction ◽

Cross Sectional ◽

X Ray ◽

Multi Scale ◽

3D Printed

This work presents multi-scale approaches to investigate 3D printed structured Mn–Na–W/SiO2 catalysts used for the oxidative coupling of methane (OCM) reaction. The performance of the 3D printed catalysts has been compared to their conventional analogues, packed beds of pellets and powder. The physicochemical properties of the 3D printed catalysts were investigated using scanning electron microscopy, nitrogen adsorption and X-ray diffraction (XRD). Performance and durability tests of the 3D printed catalysts were conducted in the laboratory and in a miniplant under real reaction conditions. In addition, synchrotron-based X-ray diffraction computed tomography technique (XRD-CT) was employed to obtain cross sectional maps at three different positions selected within the 3D printed catalyst body during the OCM reaction. The maps revealed the evolution of catalyst active phases and silica support on spatial and temporal scales within the interiors of the 3D printed catalyst under operating conditions. These results were accompanied with SEM-EDS analysis that indicated a homogeneous distribution of the active catalyst particles across the silica support.

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Hydrothermal Ageing and Its Effect on Fracture Load of Zirconia Dental Implants

Materials ◽

10.3390/ma14113103 ◽

2021 ◽

Vol 14 (11) ◽

pp. 3103

Author(s):

Laurent Gremillard ◽

Agnès Mattlet ◽

Alexandre Mathevon ◽

Damien Fabrègue ◽

Bruno Zberg ◽

...

Keyword(s):

Dental Implants ◽

Fracture Load ◽

Accelerated Ageing ◽

Dental Ceramics ◽

X Ray Diffraction ◽

X Ray ◽

Dental Restorations ◽

Different Temperatures ◽

Mechanical Performances ◽

Kinetics Of

Due to growing demand for metal-free dental restorations, dental ceramics, especially dental zirconia, represent an increasing share of the dental implants market. They may offer mechanical performances of the same range as titanium ones. However, their use is still restricted by a lack of confidence in their durability and, in particular, in their ability to resist hydrothermal ageing. In the present study, the ageing kinetics of commercial zirconia dental implants are characterized by X-ray diffraction after accelerated ageing in an autoclave at different temperatures, enabling their extrapolation to body temperature. Measurements of the fracture loads show no effect of hydrothermal ageing even after ageing treatments simulated a 90-year implantation.

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Sedimentary Clays as Geopolymer Precursor

International Journal of Engineering Research in Africa ◽

10.4028/www.scientific.net/jera.39.97 ◽

2018 ◽

Vol 39 ◽

pp. 97-111

Author(s):

F. Mostefa ◽

Nasr Eddine Bouhamou ◽

H.A. Mesbah ◽

Salima Aggoun ◽

D. Mekhatria

Keyword(s):

Sodium Hydroxide ◽

Mineralogical Composition ◽

Cementitious Materials ◽

Raw Material ◽

X Ray Diffraction ◽

Calcination Time ◽

Calorimetric Analysis ◽

X Ray ◽

Before And After ◽

Mechanical Performances

This work aims to study the feasibility of making a geopolymer cement based on dredged sediments, from the Fergoug dam (Algeria) and to evaluate their construction potential particularly interesting in the field of special cementitious materials. These sediments due to their mineralogical composition as aluminosilicates; are materials that can be used after heat treatment. Sedimentary clays were characterized before and after calcination by X-ray diffraction, ATG / ATD, spectroscopy (FTIR) and XRF analysis. The calcination was carried out on the raw material sieved at 80 μm for a temperature of 750 ° C, for 3.4 and 5 hours. The reactivity of the calcined products was measured using isothermal calorimetric analysis (DSC) on pastes prepared by mixing an alkaline solution of sodium hydroxide (NaOH) 8 M in an amount allowing to have a Na / Al ratio close to 1 (1: 1). Also, cubic mortar samples were prepared with a ratio L / S: 0.8, sealed and cured for 24 hours at 60 ° C and then at room temperature until the day they were submited to mechanical testing. to check the extent of geopolymerization. The results obtained allowed to optimize the calcination time of 5 hours for a better reactivity of these sediments, and a concentration of 8M of sodium hydroxide and more suitable to have the best mechanical performances.

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Compressibility of β-As4S4: an in situ high-pressure single-crystal X-ray study

Mineralogical Magazine ◽

10.1180/minmag.2012.076.4.12 ◽

2012 ◽

Vol 76 (4) ◽

pp. 963-973 ◽

Cited By ~ 6

Author(s):

G. O. Lepore ◽

T. Boffa Ballaran ◽

F. Nestola ◽

L. Bindi ◽

D. Pasqual ◽

...

Keyword(s):

Pressure Range ◽

Substantial Reduction ◽

Structural Data ◽

Unit Cell ◽

Van Der Waals Interactions ◽

X Ray Diffraction ◽

Unit Cell Parameters ◽

X Ray ◽

Cell Parameters ◽

Intermolecular Distances

AbstractAmbient temperature X-ray diffraction data were collected at different pressures from two crystals of β-As4S4, which were made by heating realgar under vacuum at 295ºC for 24 h. These data were used to calculate the unit-cell parameters at pressures up to 6.86 GPa. Above 2.86 GPa, it was only possible to make an approximate measurement of the unit-cell parameters. As expected for a crystal structure that contains molecular units held together by weak van der Waals interactions, β-As4S4 has an exceptionally high compressibility. The compressibility data were fitted to a third-order Birch–Murnaghan equation of state with a resulting volume V0 = 808.2(2) Å3, bulk modulus K0 = 10.9(2) GPa and K' = 8.9(3). These values are extremely close to those reported for the low-temperature polymorph of As4S4, realgar, which contains the same As4S4 cage-molecule. Structural analysis showed that the unit-cell contraction is due mainly to the reduction in intermolecular distances, which causes a substantial reduction in the unit-cell volume (∼21% at 6.86 GPa). The cage-like As4S4 molecules are only slightly affected. No phase transitions occur in the pressure range investigated.Micro-Raman spectra, collected across the entire pressure range, show that the peaks associated with As–As stretching have the greatest pressure dependence; the S–As–S bending frequency and the As–S stretching have a much weaker dependence or no variation at all as the pressure increases; this is in excellent agreement with the structural data.

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Residual Stresses Assessment in Coated Materials: Complementarity between Neutron and X-Ray Techniques

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.465.259 ◽

2011 ◽

Vol 465 ◽

pp. 259-262 ◽

Cited By ~ 1

Author(s):

M. Rogante ◽

Pavol Mikula ◽

Miroslav Vrána

Keyword(s):

Mechanical Tests ◽

Substantial Contribution ◽

Hole Drilling ◽

X Ray Diffraction ◽

Interface Area ◽

X Ray ◽

Coated Materials ◽

Coating Delamination ◽

Yield Trends ◽

Xrd Techniques

The residual stress (RS) status induced in the substrate of coated materials by the coating process plays frequently a major role in lending the component’s characteristics. RS assessment can give, thus, a substantial contribution in justifying different cases of failure or else bad performance of coated components due to e.g. the coating delamination or to other occurrences which are not simply interpretable via the conventional mechanical tests or microstructure analyses. The adoption of both neutron diffraction (ND) and X-ray diffraction (XRD) techniques has revealed its usefulness in assessing the RS values in proximity of the coating interface area, respectively, without any layer removal or hole drilling at the extreme surface. In this paper, some real cases of RS determination in coated materials by using these techniques and exploiting their complementarity are described. ND, in particular, is very suitable for crucial applications, where a much different stress situation than that assessed by XRD could be present at some depth below the surface. The results achieved can yield trends adoptable in monitoring of the coating features.

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Synthesis, Characterization and Biological Properties of Intercalated Kaolinite Nanoclays: Intercalation and Biocompatibility

Advances in Materials Science ◽

10.2478/adms-2019-0007 ◽

2019 ◽

Vol 19 (1) ◽

pp. 83-99 ◽

Cited By ~ 1

Author(s):

B. Yilmaz ◽

E. T. Irmak ◽

Y. Turhan ◽

S. Doğan ◽

M. Doğan ◽

...

Keyword(s):

Electron Microscopy ◽

Human Lymphocytes ◽

Biological Properties ◽

Attenuated Total Reflectance ◽

X Ray Diffraction ◽

Cytotoxic Effects ◽

X Ray ◽

Human Risk ◽

Transmission Electron ◽

Reflectance Ftir

AbstractThe aims of the present study were to synthesize the intercalated kaolinite samples with dimethylsulfoxide (DMSO), glutamic acid (GA), succinimide (SIM), cetylpyridiniumchloride (CPC), and hexadecyltrimethylammoniumchloride (HDTMA+); to characterize by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR), and to determine the hemocompatibility and the cytotoxic effects of the intercalated kaolinite nanoclays on human lymphocytes. It was found that the intercalation with DMSO did not cause any decrease in cell viability until its maximum concentration (500 µg/mL), however, the intercalation with SIM, CPC, and (HDTMA+) causd important decreases in lymphocyte viabilities. It was determined that no significant decrease was observed in protein content of the lymphocyte cells exposed to the kaolinite nanoclays except the ones intercalated with SIM. Furthermore, the pristine kaolinite nanoclays which were intercalated with DMSO, GA, and SIM exhibited high hemocompatibility and the nanoclays intercalated with CPC and (HDTMA+) were highly hemocompatibile for the amounts below 125 and 500 µg/mL, respectively. All the results of this work can serve for the human risk assesment of intercalated nanoclays.

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Preparation and Assessment of Heat-Treated α-Chitin Nanowhiskers Reinforced Poly(viny alcohol) Film for Packaging Application

Materials ◽

10.3390/ma11101883 ◽

2018 ◽

Vol 11 (10) ◽

pp. 1883 ◽

Cited By ~ 7

Author(s):

Chao Peng ◽

Guangxue Chen

Keyword(s):

Heat Treatment ◽

Composite Films ◽

Barrier Properties ◽

Mechanical Tests ◽

Light Transmittance ◽

Poly Vinyl Alcohol ◽

X Ray Diffraction ◽

X Ray ◽

Heat Treated ◽

Chitin Nanowhiskers

In this study, poly(vinyl alcohol) (PVA) composite films enhanced by α-chitin nanowhiskers (ChWs) were prepared through heat treatment. The obtained membranes were assessed by means of FTIR spectroscopy, X-ray diffraction, thermogravimetric analysis, regular light transmittance, mechanical tests, permeability and water absorption. The influence of the nano-component and heat treatment on the mechanical, thermal and water-resistant properties of the composite membrane were analyzed. From the results of the work, the produced films with excellent barrier properties and inexpensive raw processed materials have great prospects in packaging applications.

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Microstructures and Properties of Fe/B-Fe Coating Used in Circulating Fluidized Bed Boiler

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.66-68.1528 ◽

2011 ◽

Vol 66-68 ◽

pp. 1528-1532

Author(s):

Qi Fa Tian ◽

Hong Fei Sun

Keyword(s):

Electron Probe ◽

Circulating Fluidized Bed ◽

Steel Substrate ◽

Electric Arc ◽

Bare Metal ◽

X Ray Diffraction ◽

X Ray ◽

Transmission Electron ◽

Mechanical Performances ◽

Electronic Microscope

Electric arc praying technology was used to produce Fe/B-Fe coating on the carbon steel substrate. The microstructures was studied by means of scanning electronic microscope (SEM), X-ray diffraction (XRD), transmission electron microscope (TEM) and electron probe microanalysis (EPMA). Mechanical performances, wear resistance of coating were tested . The results showed that the resistance to abrasion and corrosion of Fe/B-Fe coating was respectively 16 times and 5 to 6 times higher than those of bare metal.

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Development of 3D Bioactive Scaffolds through 3D Printing Using Wollastonite–Gelatin Inks

Polymers ◽

10.3390/polym12102420 ◽

2020 ◽

Vol 12 (10) ◽

pp. 2420 ◽

Cited By ~ 1

Author(s):

Filis Curti ◽

Izabela-Cristina Stancu ◽

Georgeta Voicu ◽

Horia Iovu ◽

Cristina-Ioana Dobrita ◽

...

Keyword(s):

3D Printing ◽

Bone Repair ◽

Homogeneous Distribution ◽

Orthopedic Trauma ◽

Fish Gelatin ◽

Mass Ratio ◽

X Ray Diffraction ◽

X Ray ◽

Bioactive Scaffolds ◽

Microscopy Images

The bioactivity of scaffolds represents a key property to facilitate the bone repair after orthopedic trauma. This study reports the development of biomimetic paste-type inks based on wollastonite (CS) and fish gelatin (FG) in a mass ratio similar to natural bone, as an appealing strategy to promote the mineralization during scaffold incubation in simulated body fluid (SBF). High-resolution 3D scaffolds were fabricated through 3D printing, and the homogeneous distribution of CS in the protein matrix was revealed by scanning electron microscopy/energy-dispersive X-ray diffraction analysis (SEM/EDX) micrographs. The bioactivity of the scaffold was suggested by an outstanding mineralization capacity revealed by the apatite layers deposited on the scaffold surface after immersion in SBF. The biocompatibility was demonstrated by cell proliferation established by MTT assay and fluorescence microscopy images and confirmed by SEM micrographs illustrating cell spreading. This work highlights the potential of the bicomponent inks to fabricate 3D bioactive scaffolds and predicts the osteogenic properties for bone regeneration applications.

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Incorporation of Mg in phase Egg, AlSiO3OH: Toward a new polymorph of phase H, MgSiH2O4, a carrier of water in the deep mantle

American Mineralogist ◽

10.2138/am-2020-7204 ◽

2020 ◽

Vol 105 (1) ◽

pp. 132-135 ◽

Cited By ~ 1

Author(s):

Luca Bindi ◽

Aleksandra Bendeliani ◽

Andrey Bobrov ◽

Ekaterina Matrosova ◽

Tetsuo Irifune

Keyword(s):

Crystal Structure ◽

Solid Solution ◽

Lower Mantle ◽

Water Cycle ◽

Molecular Water ◽

Hydroxyl Groups ◽

X Ray Diffraction ◽

Coordination Polyhedra ◽

X Ray ◽

Mg Substitution

Abstract The crystal structure and chemical composition of a crystal of Mg-bearing phase Egg with a general formula M1−x3+Mx2+SiO4H1+x (M3+ = Al, Cr; M2+ = Mg, Fe), where x = 0.35, produced by subsolidus reaction at 24 GPa and 1400 °C of components of subducted oceanic slabs (peridotite, basalt, and sediment), was analyzed by electron microprobe and single-crystal X-ray diffraction. Neglecting the enlarged unit cell and the consequent expansion of the coordination polyhedra (as expected for Mg substitution for Al), the compound was found to be topologically identical to phase Egg, AlSiO3OH, space group P21/n, with lattice parameters a = 7.2681(8), b = 4.3723(5), c = 7.1229(7) Å, β = 99.123(8)°, V = 223.49(4) Å3, and Z = 4. Bond-valence considerations lead to hypothesize the presence of hydroxyl groups only, thereby excluding the presence of the molecular water that would be present in the hypothetical end-member MgSiO3·H2O. We thus demonstrate that phase Egg, considered as one of the main players in the water cycle of the mantle, can incorporate large amounts of Mg in its structure and that there exists a solid solution with a new hypothetical MgSiH2O4 end-member, according to the substitution Al3+ ↔ Mg2+ + H+. The new hypothetical MgSiH2O4 end-member would be a polymorph of phase H, a leading candidate for delivering significant water into the deepest part of the lower mantle.

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