Calcium substituted with magnesium, silver and zinc in hydroxyapatite: a review

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Anuradha Mahanty ◽  
Deep Shikha
Keyword(s):  
Mechanical Properties ◽  
Inhibitory Effect ◽  
The Body ◽  
Magnesium Ions ◽  
Chemical Formula ◽  
Natural Bone ◽  
The Matrix ◽  
Long Time ◽  
Good Biocompatibility

Abstract Hydroxyapatite with the chemical formula Ca10(-PO4)6(OH)2 is an important bioceramic well known for its high osteoconductive properties, non-toxic nature, high bioactivity and good biocompatibility. Moreover, it is known to mimic natural bone. Inspite of the above mentioned advantages, it has certain disadvantages such as having poor mechanical properties, being brittle, not showing an inhibitory effect on microbes and taking a long time to resorb in the body. These disadvantages can be covered up by the addition of dopants which include cations, anions and polymers. These are sufficiently known to improve the properties of hydroxyapatite. This review focuses on the substitution of hydroxyapatite with silver, zinc, magnesium ions and alloys to show the changes in the morphology and biocompatible properties of hydroxyapatite after substitution of the ions in the matrix.

scholarly journals PENGARUH SPUTTERING TiN TERHADAP KEKASARAN, KEKERASAN PERMUKAAN MATERIAL AISI316L

2019 ◽  
Vol 18 (3) ◽  
pp. 331-338
Author(s):  
Jemssy Ronald Rohi ◽  
Priyo Tri Iswanto ◽  
Tjipto Sujitno ◽  
Erich Umbu Kondi
Keyword(s):  
Mechanical Properties ◽  
Surface Roughness ◽  
Corrosion Resistance ◽  
Deposition Time ◽  
Low Cost ◽  
Surface Hardness ◽  
The Body ◽  
Aisi 316L ◽  
Good Corrosion Resistance ◽  
Long Time

AISI 316L is widely used for implantation in orthopedic surgery due to its good corrosion resistance, mechanical properties and low cost. However, AISI 316L is not well suited for biocompatibility with the body, so implant material with AISI 316L can’t be used for a long time. One way to improve the corrosion resistance and mechanical properties of AISI 316L is to perform a surface treatment such as sputtering. This study discusses the effect of deposition sputtering TiN of 60, 90, 120 and 150 minutes on roughness and surface hardness at a ratio of argon gas and nitrogen to 80% Ar:20% N2. The results of the surface roughness value of the TiN sputtering layer deposited to AISI 316L for 60, 90, 120, and 150 minutes were 0.02 μm, 0.04 μm, 0.06 μm, and 0.04 μm respectively. This shows that the coating time of TiN in AISI 316L has no significant influence on value of surface roughness. Surface hardness results at 60, 90, 120, and 150 minutes were obtained with 268 HVN, 275 HVN, 278 HVN and 282 HVN. Increased hardness value, as the TiN thin layer has a higher hardness value compared to AISI 316L. The longer the deposition time, the more layers are formed and the layer becomes thicker. With the thickness of the layer, the density at the grain boundary increases. Because the higher density leads to grain growth, in which form micropores.

Influence of Service Time on the Microstructure and High Temperature Mechanical Properties of T23 Boiler Tube

2017 ◽  
Vol 898 ◽  
pp. 711-718 ◽  
Author(s):  
Cheng He ◽  
Bao Liang Shi ◽  
Wen Sheng Li ◽  
Jian Ping Zhao ◽  
Kai Xu ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
High Temperature ◽  
Service Time ◽  
Testing Machine ◽  
Tensile Testing Machine ◽  
Time Service ◽  
High Temperature Mechanical Properties ◽  
The Matrix ◽  
Long Time

The influence of long time service on the microstructure and high temperature mechanical properties of T23 steel was studied by optical microscopy, scanning electron microscopy, transmission electron microscopy and tensile testing machine. Results showed that lathy bainite ferrite disappears with the increasing service time, both the size and number of the carbides increases, and M23C6 carbides transform into M6C carbides rich in W element. The service process also has a significant influence on the recovery. Sub-grains were found at the grain boundaries with little dislocations in the matrix after 27448 h service time. After running for 27448 h the microstructure degradation of T23 steel is serious. High temperature tensile properties of T23 are closely related to the alloy aging degree. The reasons for the decrease of high temperature mechanical properties after long time service included microstructure degradations such as the increase of both the size and quantity of M23C6 carbides, the transformation of M23C6 to M6C, the desolution of Cr,W,and Mo elements, the decrease of the dislocation density and the occurrence of the sub-grains.

scholarly journals Fabrication of Cellulose Acetate/Cellulose-HA Composite Films for Bone Fixation

2018 ◽  
Vol 778 ◽  
pp. 325-330 ◽  
Author(s):  
Fatima Nisar ◽  
Usama bin Khalid ◽  
Muhammad Aftab Akram ◽  
Sofia Javed ◽  
Mohammad Mujahid
Keyword(s):  
Mechanical Properties ◽  
Cellulose Acetate ◽  
Composite Films ◽  
The Body ◽  
Experimental Procedure ◽  
Natural Bone ◽  
Bone Fixation ◽  
Cellulose Microfibers ◽  
Inorganic Mineral ◽  
Tissue Rejection

Bone is a rigid and constantly remodeling organ, a type of tissue which provides support and protects organs in the body, and together they form the skeleton [1]. Materials generally used for implants bear tissue rejection and produce toxins on degradation [2]. Our objective is to synthesize a biocompatible composite of Hydroxyapatite (HA) and Cellulose using Cellulose Acetate as a matrix which mimics the properties of natural bone that can be used for bone replacements. Bone is composed of calcium phosphate (HA) and collagen, which gives bone desired properties [3]. Hydroxyapatite is the inorganic mineral found in the bone and is preferred due to its mechanical properties, biocompatibility, slow degradation in physiological environment and bioactivity [4]. Cellulose, structural component in plants is similar in properties to collagen therefore the properties of cellulose [4], HA and cellulose acetate are exploited to achieve our results. The experimental procedure is divided into two major steps; extraction of cellulose microfibers (CMF) from cotton followed by dispersion of cellulose and HA in cellulose acetate then casting membranes of the composite.

Obtaining and characterization of the alumina-zirconia nanocomposite

2012 ◽  
Vol 1386 ◽  
Author(s):  
Eliria M. J. A. Pallone ◽  
Kátia L. Silva ◽  
Roberto Tomasi ◽  
Vania T. Hernandes ◽  
Cecilia Zavaglia
Keyword(s):  
Mechanical Properties ◽  
Mechanical Resistance ◽  
Application Area ◽  
Broad Application ◽  
Good Dispersion ◽  
The Matrix ◽  
Good Biocompatibility ◽  
Nanometric Particles ◽  
Resistance To Wear

ABSTRACTCeramics of alumina of high density and purity can have a broad application area due to the combination of the excellent properties such as resistance to corrosion, good biocompatibility, and high resistance to wear and moderate mechanical resistance. But its low fracture toughness limits its range of applications. One possibility of improvement in the properties of these materials might be in the use of nanometric inclusions of ZrO2 into the matrix of Al2O3. The aim of this paper was to obtain and characterize the nanocomposites of alumina containing 0, 5, 10, 15 and 30 vol% of nanometric zirconium, seeking improvements in the mechanical properties and its comparison with values found for the matrix without the inclusion. For that, nanometric particles of ZrO2 were added into the matrix of alumina in the different proportions, using mixture of suspensions. The samples of alumina and nanocomposites of alumina-zirconium were physically, microstructurally and mechanically characterized. The results obtained, showed the efficiency of the used process, obtaining a good dispersion of the particles of zirconium in the matrix of alumina. The adding of up to 15vol% nanometric zirconium in the matrix of alumina promoted an increase in the values of the mechanical properties when compared with alumina. For the nanocomposites containing 30vol%, a good dispersion of the zirconium inclusions did not happen, leading to inferior values in the measured properties.

Hydroxyapatite Coating Improves Bone Integration and Interface Strength of Polymer Implants in Bone

2008 ◽  
Vol 396-398 ◽  
pp. 331-335
Author(s):  
Joerg Brandt ◽  
M. Pfennig ◽  
Christian Bieroegel ◽  
Wolfgang Grellmann ◽  
Anke Bernstein
Keyword(s):  
Mechanical Properties ◽  
Hip Joint ◽  
Femoral Stem ◽  
The Body ◽  
Polymer Materials ◽  
Metal Alloys ◽  
Load Bearing ◽  
Natural Bone ◽  
Wide Range ◽  
Joint Prostheses

Many attempts had been made to improve the durability of artificial joint replacement and other orthopaedic implants by approaching the mechanical properties of bone and artificial material. The most joint prostheses used today are manufactured of metal alloys based on cobalt, chromium or titanium. The mechanical stiffness of these materials is much higher than that of natural bone resulting in adverse effects such as local overloading on one hand or stress shielding phenomena with the lack of adequate mechanical load on the other. Both mechanisms contribute to earl loosening and failure of implants. Polymer materials may deliver mechanical properties very similar to bone and their mechanical behaviour may be modified in a wide range during the process of manufacturing. First attempts to lower the stiffness of the implant material and to gain the stiffness range of natural bone were made in the seventies by R. Matthys with his concept of “isoelastic hip prosthesis”. In this prosthesis the femoral stem was manufactured of polyacetal, a thermoplastic polymer with very good biocompatibility and elastic properties which are much nearer to bone than common metal alloys. While the prosthesis showed good results during the mechanical testing the clinical use in vivo became a disaster. Shortly after implantation polyacetal was degraded in the body and broke down under the immense loading of the human hip joint. Later attempts to use polymer materials alone for load bearing implants also failed in clinical practice over a long time because the mechanical interlocking between bone and implant was not sufficient for the biological demand. To make the outstanding properties of polymer materials useable for load bearing implants they are backed with metal alloys (as polyethylene for hip joint cups) until the presence. Only recent developments of polymer science succeeded in the use of polymers for loaded implants. One of the most interesting materials seems to be the polyetheretherketone (PEEK) which is successfully used for spinal fusion cages [2] and computerdesigned individual implants for defect reconstruction in the skull [4] meanwhile. A pre-clinical study of a new anatomically shaped flexible acetabular cup reported satisfactory results recently [3].

Morphology and Mechanical Properties of Polyethylene Terephthalate/Ethylene Propylene Diene Monomer (PET/EPDM) in the Presence of Nanoclay

2020 ◽  
Vol 57 (3) ◽  
pp. 249-259
Author(s):  
Baifen Liu ◽  
Mohammad Mirjalili ◽  
Peiman Valipour ◽  
Sajad Porzal ◽  
shirin Nourbakhsh
Keyword(s):  
Mechanical Properties ◽  
Impact Strength ◽  
Thermal Destruction ◽  
Processing Temperature ◽  
Tem Analysis ◽  
Maximum Stiffness ◽  
Cloisite 30B ◽  
Nano Clay ◽  
The Matrix ◽  
Sample Maximum

This research deals with the mechanical properties, microstructure, and interrelations of triple nanocomposite based on PET/EPDM/Nanoclay. These properties were examined in different percentages of PET/EPDM blend with compatibilizer (Styrene-Ethylene/Butylene-Styrene)-G-(Maleic anhydrate) (SEBS-g-MAH). Results showed that the addition of 15% SEBS-g-MAH improved the toughness and impact strength of this nanocomposite. SEM micrographs indicated the most stable fuzzy microstructure in a 50/50 mixture of scattered phases of EPDM/SEBS-g-MAH. The effects of percentages of 1, 3, 5, 7 nanoclay Cloisite 30B (C30B) on the improvement of the properties were evaluated. With the addition of nano clay, the toughness and impact strength was reduced. Thermal destruction of nanoclay in processing temperature led to the decreasing dispersion of clay plates in the matrix and a reduction in the distances of nano clay plates in the composite compared to pure nano clay. XRD and TEM analysis was used to demonstrate the results. By adding 1% of nanoclay to the optimal sample, maximum stiffness, and Impact strength, among other nanocomposites, was achieved.

Inhibition of Yeast Growth by Tryptamine and Recovery with Tryptophan

2020 ◽  
Vol 16 (1) ◽  
pp. 48-52 ◽  
Author(s):  
Chandrika Kadkol ◽  
Ian Macreadie
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Carbon Source ◽  
Competitive Inhibition ◽  
Yeast Species ◽  
Inhibitory Effect ◽  
The Body ◽  
Inhibitory Effects ◽  
Trna Synthetases ◽  
Fermentative Growth ◽  
Biogenic Monoamine

Background: Tryptamine, a biogenic monoamine that is present in trace levels in the mammalian central nervous system, has probable roles as a neurotransmitter and/or a neuromodulator and may be associated with various neuropsychiatric disorders. One of the ways tryptamine may affect the body is by the competitive inhibition of the attachment of tryptophan to tryptophanyl tRNA synthetases. Methods: This study has explored the effects of tryptamine on growth of six yeast species (Saccharomyces cerevisiae, Candida glabrata, C. krusei, C. dubliniensis, C. tropicalis and C. lusitaniae) in media with glucose or ethanol as the carbon source, as well as recovery of growth inhibition by the addition of tryptophan. Results: Tryptamine was found to have an inhibitory effect on respiratory growth of all yeast species when grown with ethanol as the carbon source. Tryptamine also inhibited fermentative growth of Saccharomyces cerevisiae, C. krusei and C. tropicalis with glucose as the carbon source. In most cases the inhibitory effects were reduced by added tryptophan. Conclusion: The results obtained in this study are consistent with tryptamine competing with tryptophan to bind mitochondrial and cytoplasmic tryptophanyl tRNA synthetases in yeast: effects on mitochondrial and cytoplasmic protein synthesis can be studied as a function of growth with glucose or ethanol as a carbon source. Of the yeast species tested, there is variation in the sensitivity to tryptamine and the rescue by tryptophan. The current study suggests appropriate yeast strains and approaches for further studies.

scholarly journals Preparation of Long Sisal Fiber-Reinforced Polylactic Acid Biocomposites with Highly Improved Mechanical Performance

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1124
Author(s):  
Zhifang Liang ◽  
Hongwu Wu ◽  
Ruipu Liu ◽  
Caiquan Wu
Keyword(s):  
Mechanical Properties ◽  
Polylactic Acid ◽  
Mechanical Performance ◽  
Tensile Elongation ◽  
Sisal Fiber ◽  
Fiber Reinforced ◽  
Impact Performance ◽  
The Matrix ◽  
Blending Process ◽  
Extension Direction

Green biodegradable plastics have come into focus as an alternative to restricted plastic products. In this paper, continuous long sisal fiber (SF)/polylactic acid (PLA) premixes were prepared by an extrusion-rolling blending process, and then unidirectional continuous long sisal fiber-reinforced PLA composites (LSFCs) were prepared by compression molding to explore the effect of long fiber on the mechanical properties of sisal fiber-reinforced composites. As a comparison, random short sisal fiber-reinforced PLA composites (SSFCs) were prepared by open milling and molding. The experimental results show that continuous long sisal fiber/PLA premixes could be successfully obtained from this pre-blending process. It was found that the presence of long sisal fibers could greatly improve the tensile strength of LSFC material along the fiber extension direction and slightly increase its tensile elongation. Continuous long fibers in LSFCs could greatly participate in supporting the load applied to the composite material. However, when comparing the mechanical properties of the two composite materials, the poor compatibility between the fiber and the matrix made fiber’s reinforcement effect not well reflected in SSFCs. Similarly, the flexural performance and impact performance of LSFCs had been improved considerably versus SSFCs.

scholarly journals Novel Hydrogels of Chitosan and Poly (vinyl alcohol) Reinforced with Inorganic Particles of Bioactive Glass

Polymers ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 691
Author(s):  
O. Sánchez-Aguinagalde ◽  
Ainhoa Lejardi ◽  
Emilio Meaurio ◽  
Rebeca Hernández ◽  
Carmen Mijangos ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Drug Release ◽  
Bioactive Glass ◽  
Vinyl Alcohol ◽  
Release Kinetics ◽  
The Body ◽  
Poly Vinyl Alcohol ◽  
X Ray Diffraction ◽  
Inorganic Particles ◽  
Release Studies

Chitosan (CS) and poly (vinyl alcohol) (PVA) hydrogels, a polymeric system that shows a broad potential in biomedical applications, were developed. Despite the advantages they present, their mechanical properties are insufficient to support the loads that appear on the body. Thus, it was proposed to reinforce these gels with inorganic glass particles (BG) in order to improve mechanical properties and bioactivity and to see how this reinforcement affects levofloxacin drug release kinetics. Scanning electron microscopy (SEM), X-ray diffraction (XRD), swelling tests, rheology and drug release studies characterized the resulting hydrogels. The experimental results verified the bioactivity of these gels, showed an improvement of the mechanical properties and proved that the added bioactive glass does affect the release kinetics.

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