Fabrication of α-TCP, HAp Functionally Graded Porous Beads

2008 ◽  
Vol 57 ◽  
pp. 135-138
Author(s):  
Yuji Kajihata ◽  
Teruo Asaoka ◽  
Katsuko S. Furukawa ◽  
Takashi Ushida ◽  
T. Tateishi
Keyword(s):  
Surface Layer ◽  
High Strength ◽  
Functionally Graded ◽  
The Body ◽  
Acid Solutions ◽  
Bioactive Material ◽  
Hydrolytic Reaction ◽  
Rate Of Absorption ◽  
Porous Beads ◽  
Good Cell

HAp (Hydroxyapatite) and α-TCP (alpha tribasic calcium phosphate) are non-toxic to human cells and, thus, have been studied for applications as biomaterials. HAp is a bioactive material that is not readily absorbed by the body; it offers both high strength and better tissueadhesive properties than α-TCP. In contrast, α-TCP is highly bioabsorbable; it is quickly absorbed by the body, and, therefore, for example, disappears before bone is completely replaced. If porous beads could be fabricated that would take advantage of the useful properties of α-TCP and HAp, they could be used as excellent scaffolds for cultivating cells. In the present study, ceramic beads with α-TCP at the center were fabricated and coated with a functionally graded film of HAp. A scaffold based on this configuration would be expected to have the following characteristics: good cell adhesion; strong beads; and a rate of absorption into the body that would be easy to control. In addition, to accelerate the formation of porous structure, some acid solutions were used to dissolve the beads surface layer and to penetrate pores toward inside of the bead. HAp formation through hydrolytic reaction seemed to be promoted by these acid solutions.

Study on Bone Cell Adaptability of α-TCP/HAp Functionally Graded Porous Beads for Biomaterials Application

2010 ◽  
Vol 76 ◽  
pp. 143-146
Author(s):  
S. Ohtake ◽  
T. Asaoka ◽  
K. Furukawa ◽  
T. Ushida ◽  
T. Tateishi
Keyword(s):  
Bone Cells ◽  
High Strength ◽  
Bone Cell ◽  
Functionally Graded ◽  
The Body ◽  
Tissue Adhesive ◽  
Adhesive Properties ◽  
Living Body ◽  
Porous Beads

Porous beads of bioactive ceramics such as HAp, TCP are considered to be promising as excellent scaffolds for cultivating bone cells. To realize this type of beads which maintains the function of scaffold with sufficient strength up to growth of new bone, and is expected to absorbed completely after the growth, a-TCP/ HAp functionally graded porous beads were fabricated. HAp is bioactive material which has both high strength and better tissue-adhesive properties, but that is not readily absorbed by the human body. On the contrary, a-TCP is highly bioabsorbable; it is quickly absorbed by the body, and, therefore, disappears before bone is completely replaced. Fabricated new beads are composed of a-TCP at the center and HAp at the surface, to control the solubility in living body. Bone cell adaptability of these beads were confirmed in vitro.

Solubility Control of αTCP-HAp Functionally Graded Porous Beads in SBF for Biomaterial Use

2010 ◽  
Vol 638-642 ◽  
pp. 2021-2027
Author(s):  
Teruo Asaoka ◽  
Yuji Kajihata ◽  
Katsuko Furukawa ◽  
Takashi Ushida ◽  
Tetsuya Tateishi
Keyword(s):  
Body Fluid ◽  
Absorption Rate ◽  
Bone Cells ◽  
High Strength ◽  
Functionally Graded ◽  
The Body ◽  
Tissue Adhesive ◽  
Adhesive Properties ◽  
Living Body ◽  
Porous Beads

As excellent scaffolds for cultivating bone cells, porous beads of bioactive ceramics such as HAp, TCP are considered to be promising. HAp and α-TCP are well known as non-toxic bioceramics to human cells, but their behavior in living body fluid are different. HAp is bioactive material which has both high strength and better tissue-adhesive properties, but that is not readily absorbed by the human body. On the contrary, α-TCP is highly bioabsorbable; it is quickly absorbed by the body, and, therefore, disappears before bone is completely replaced. To realize a composite which has suitable solubility in living body fluid, α-TCP/ HAp functionally graded porous beads were fabricated by the method of spheroidization in liquid nitrogen. This type of composite maintains the function of scaffold with sufficient strength up to growth of new bone, and after the growth, it is expected to absorbed completely in the body. In the present study, ceramic beads with α-TCP at the center were fabricated and coated with a functionally graded layer of HAp. By controlling the thickness of HAp layer, which could be realized by changing time of hydrolytic reaction, the absorption rate into the body would be easily controlled. In addition, to accelerate the formation of porous structure, some acid solutions were used to dissolve the beads surface and to penetrate pores toward inside of the beads. Observed surface and inner structure by SEM, also the measured change in absorption rate will be presented.

Effect of diamond burnishing parameters on the state of the processed surface layer of billets made of high-strength "30ХГСН2А-ВД" steel

2020 ◽  
pp. 82-86
Author(s):  
A.N. Shvetsov ◽  
D.L. Skuratov
Keyword(s):  
Surface Layer ◽  
Residual Stresses ◽  
Strain Hardening ◽  
Processing Speed ◽  
Synthetic Diamond ◽  
High Strength ◽  
The State ◽  
Diamond Burnishing

The influence of the burnishing force, tool radius, processing speed and feed on the distribution of circumferential and axial residual strses, microhardness and the depth of strain hardening in the surface layer when pr ssing of "30ХГСН2А-ВД" steel with synthetic diamond "ACB-1" is considered. Empirical dependencies determining these parameters are given. Keywords diamond burnishing, strain hardening depth, circumferential residual stresses, axial residual stresses, microhardness. [email protected], [email protected]

Relationship between Microstructure and Mechanical Properties in Q&P-Steels

2016 ◽  
Vol 879 ◽  
pp. 1933-1938 ◽  
Author(s):  
Richard G. Thiessen ◽  
Georg Paul ◽  
Roland Sebald
Keyword(s):  
Mechanical Properties ◽  
Dual Phase Steel ◽  
High Strength Steels ◽  
High Strength ◽  
The Body ◽  
Advanced High Strength Steels ◽  
Passenger Safety ◽  
Back Scattering ◽  
Body In White ◽  
Expected Increase

Third-Generation advanced high strength steels are being developed with the goal of reducing the body-in-white weight while simultaneously increasing passenger safety. This requires not only the expected increase in strength and elongation, but also improved local formability. Optimizing elongation and formability were often contradictory goals in dual-phase steel developments. Recent results have shown that so-called "quench and partitioning" (Q&P) concepts can satisfy both requirements [1]. Many Q&P-concepts have been studied at thyssenkrupp Steel Europe. Thorough investigation of the microstructure has revealed relationships between features such as the amount, morphology and chemical stability of the retained austenite and the obtained mechanical properties. An evaluation of the lattice strain by means of electron-back-scattering-diffraction has also yielded a correlation to the obtained formability. The aim of this work is to present the interconnection between these microstructural features and propose hypotheses for the explanation of how these features influence the macroscopically observed properties.

Additive manufacturing of Inconel625-HSLA Steel functionally graded material by wire arc additive manufacturing

2021 ◽  
Vol 118 (5) ◽  
pp. 502
Author(s):  
Jiarong Zhang ◽  
Xinjie Di ◽  
Chengning Li ◽  
Xipeng Zhao ◽  
Lingzhi Ba ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Chemical Composition ◽  
Primary Dendrite ◽  
Hsla Steel ◽  
High Strength ◽  
Phase Evolution ◽  
Functionally Graded ◽  
Graded Materials ◽  
Graded Material ◽  
Wire Arc Additive Manufacturing

Functional graded materials (FGMs) have been widely applied in many engineering fields, and are very potential to be the substitutions of dissimilar metal welding joints due to their overall performance. In this work, the Inconel625-high-strength low-alloy (HSLA) Steel FGM was fabricated by wire arc additive manufacturing (WAAM). The chemical composition distribution, microstructure, phase evolution and mechanical properties of the FGM were examined. With the increasing of HSLA Steel, the chemical composition appeared graded distribution, and the primary dendrite spacing was largest in graded region with 20%HSLA Steel and then gradually decreased. And the main microstructure of the FGM transformed from columnar dendrites to equiaxed dendrites. Laves phase precipitated along dendrites boundary when the content of HSLA Steel was lower than 70% and Nb-rich carbides precipitated when the content of HSLA Steel exceeded to 70%. Microhardness and tensile strength gradually decreased with ascending content of HSLA Steel, and had a drastic improvement (159HV to 228HV and 355Mpa to 733Mpa) when proportion of HSLA Steel increased from 70% to 80%.

Practical Application of the Similarity Law of Structures in the Reconstruction of the Surface Layer of Bricks

2021 ◽  
Vol 1017 ◽  
pp. 21-30
Author(s):  
Victor Danilov ◽  
Arkady Ayzenshtadt ◽  
Maria Frolova
Keyword(s):  
Surface Layer ◽  
Experimental Studies ◽  
Calcium Content ◽  
Degradation Process ◽  
The Body ◽  
Atmospheric Water ◽  
A Value ◽  
Architectural Monument ◽  
Similarity Law ◽  
Selection Of

This paper discusses the results of experimental studies on the selection of the repair mixture compound for recreating the surface layer of the historical brick of the 18th century architectural monument “Commercial Bank” in Arkhangelsk. According to the research results, it was found that the historical brick has a relatively higher density and increased calcium content than the modern one. The characteristics of the surfaces of the analyzed materials based on the component indicators of specific surface energy showed that the brick of 1859, characterized by the highest degree of destruction, has the maximum value of the polar energy component. This fact may indicate a greater hydrophilicity of the surface in relation to atmospheric water and, as a result, a more intensive degradation process. It is established that the composition of the repair mixture with the addition of brick crumbs in the amount of 50 % has a value of the polar part of the surface tension equal to similar parameters for historical bricks (1786 and 1859) after their preliminary priming. The use of this mixture to recreate the surface layer of the brick will allow atmospheric water to pass freely through the repair compound and the body of the brick, without concentrating on the interface and without causing its destruction and detachment when drying.

Fabrication of α-TCP, HAp Functionally Graded Porous Beads

2008 ◽  
pp. 135-138
Author(s):  
Yuji Kajihata ◽  
Teruo Asaoka ◽  
Katsuko S. Furukawa ◽  
Takashi Ushida ◽  
T. Tateishi
Keyword(s):  
Functionally Graded ◽  
Porous Beads

scholarly journals An Overview on the Tribological Performance of Titanium Alloys with Surface Modifications for Biomedical Applications

Lubricants ◽  
2019 ◽  
Vol 7 (8) ◽  
pp. 65 ◽  
Author(s):  
Kaur ◽  
Ghadirinejad ◽  
Oskouei
Keyword(s):  
Wear Resistance ◽  
Corrosion Resistance ◽  
Titanium Alloys ◽  
Weight Ratio ◽  
High Strength ◽  
Surface Modifications ◽  
Tribological Performance ◽  
The Body ◽  
High Wear Resistance ◽  
Medical Implants

The need for metallic biomaterials will always remain high with their growing demand in joint replacement in the aging population. This creates need for the market and researchers to focus on the development and advancement of the biometals. Desirable characteristics such as excellent biocompatibility, high strength, comparable elastic modulus with bones, good corrosion resistance, and high wear resistance are the significant issues to address for medical implants, particularly load-bearing orthopedic implants. The widespread use of titanium alloys in biomedical implants create a big demand to identify and assess the behavior and performance of these alloys when used in the human body. Being the most commonly used metal alloy in the fabrication of medical implants, mainly because of its good biocompatibility and corrosion resistance together with its high strength to weight ratio, the tribological behavior of these alloys have always been an important subject for study. Titanium alloys with improved wear resistance will of course enhance the longevity of implants in the body. In this paper, tribological performance of titanium alloys (medical grades) is reviewed. Various methods of surface modifications employed for titanium alloys are also discussed in the context of wear behavior.

A bio-inspired high strength three-layer nanofiber vascular graft with structure guided cell growth

2017 ◽  
Vol 5 (20) ◽  
pp. 3758-3764 ◽  
Author(s):  
Kai Liu ◽  
Nü Wang ◽  
Wenshuo Wang ◽  
Lianxin Shi ◽  
Hao Li ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Cell Growth ◽  
Vascular Graft ◽  
High Strength ◽  
Vessel Remodeling ◽  
Good Cell ◽  
Cell Biocompatibility

A bio-inspired three-layer vascular graft with strong mechanical properties and good cell biocompatibility was fabricated by electrospinning. It will play an important role in vessel remodeling and regeneration.

SUBCUTANEOUS AND INTRAVENOUS ADMINISTRATION OF DESMOPRESSIN (DDAVP) TO HEMOPHILIACS: PLASMA PHARMACOKINETICS AND FACTOR VIII (VIII:C) RESPONSES

1987 ◽  
Author(s):  
P M Mannucci ◽  
V Vicente ◽  
I Alberca ◽  
E Sacchi ◽  
A S Harris ◽  
...  
Keyword(s):  
Hemophilia A ◽  
The Body ◽  
Intravenous Route ◽  
Maximum Increase ◽  
Time Curve ◽  
Patient Response ◽  
Routes Of Administration ◽  
Time To Peak ◽  
Rate Of Absorption ◽  
Plasma Pharmacokinetics

Reported studies dealing with the clinical use of DDAVP in mild and moderate hemophilia A patients show a very large between-patient variability for the maximum increase of VIII:C after the drug given intravenously (i.v.) or subcutaneously (s.c.). By measuring DDAVP plasma levels with a sensitive and specific RIA method, we elected to evaluate whether or not between-patient response variability was related to the variability of DDAVP levels achieved in their plasma. To this purpose 14 moderate or mild hemophilic volunteers (baseline VIII : C 4 to 31 U/dL) were randomly given 0.3 pg/Kg of i.v. or s.c. DDAVP with a between-treatment interval of 15 - 30 days. Plasma DDAVP pharmacokinetics in relation to the routes of administration are shown in the table.Pack levels (Cmax) were higher after i.v. DDAVP (p < 0.02). Time to peak levels (tmax) was shorter for i.v. DDAVP (p < 0.001). There was no difference between i.v. and s.c. DDAVP for plasma time curve (AUC) and half-life (t½).The bioavailability of the s.c. route relative to the i.v. route was 85 ° 32%. Of further interest, was the greater variability of the i.v. pharmacokinetics compared to the s.c. data. These differences were reflected in the VIII:C response. Maximum VIII:C increase over baseline levels was 3.2 ° 2.4 fold (i.v.) and 3.2 ° 1.3 fold (s.c.) (n.s.).Thus the i.v. route gave a marginally greater response but the effect was more variable than the s.c. route. Finally, no significant correlation was found between the VIII:C response and plasma DDAVP levels for either route of administration (i.v. route r = 0.03, s.c. route r = 0.23).These findings establish the subcutaneous route to be bioequivalent in effect to the intravenous route with less variation. This study also demonstrates that the VIII:C response to DDAVP is neither a function of the rate of absorption of the corrpound into the body nor the magnitude of the plasma concentration.

Sign in / Sign up

Export Citation Format

Share Document