Statistical Analysis of Surface and Sub-Surface Residual Stress Fields in Retrieved Alumina Femoral Heads after Long-Term Implantation

2006 ◽  
Vol 309-311 ◽  
pp. 1251-1256
Author(s):  
Toshiyuki Tateiwa ◽  
Kengo Yamamoto ◽  
T. Kumakura ◽  
F. Variola ◽  
Giuseppe Pezzotti ◽  
...  
Keyword(s):  
Residual Stress ◽  
Femoral Head ◽  
Microscopic Analysis ◽  
Ceramic Materials ◽  
Joint Surface ◽  
Spectroscopic Techniques ◽  
Surface Residual Stress ◽  
Testing Procedures ◽  
Femoral Heads

The surface of retrieved alumina (Al2O3) femoral heads was investigated by piezo-spectroscopic techniques based on confocal photo-stimulated fluorescence. The micrometric spatial resolution of the laser beam impinging on the investigated joint surface (typically about 1 $m in lateral resolution) enabled us estimating patterns and magnitude of residual stress in extremely narrow zones, at least comparable with the grain size of the material. According to a statistical collection of data on a microscopic level, it was possible to assess the retrieved femoral heads in-toto, thus extending the microscopic analysis to the entire surface of the joint. A stress field was found, which mainly arose from loading history, and displacements acting on the femoral head during its lifetime. Residual stress data enabled us to draw interesting conclusions about the role of the material microstructure and the peculiar kinetic mechanisms involved with the use of the joint. Spectroscopic techniques, which are complementary to in vitro testing procedures and theoretical stress analyses based on finite-element methods, can be very useful in improving the design of the femoral head and in optimizing the microstructural characteristics of the ceramic materials employed.

Study Progress on Grinding Surface Residual Stresses for Nano-Ceramic Coatings

2013 ◽  
Vol 753-755 ◽  
pp. 277-280 ◽  
Author(s):  
Wei Xiang Liu
Keyword(s):  
Residual Stress ◽  
High Hardness ◽  
Ceramic Materials ◽  
Ceramic Coatings ◽  
Grinding Process ◽  
Monitoring And Control ◽  
Surface Residual Stress ◽  
Surface Residual Stresses ◽  
Process Monitoring And Control ◽  
Grinding Mechanism

Nano-ceramic materials had high hardness and wear resistance. Combined with current technology and cost saving, nanostructured coatings technology were carried out, using HVOF ( high velocity oxygen fuel) or plasma spraying technique can obtain high quality ceramic coating on metal substrate. Ceramic coatings produced cracks in the grinding due to grinding surface residual stress. the coatings grinding surface residual stress of engineering ceramics have been researched, grinding surface residual stress in the nanostructured ceramic coatings are being researched. the researches in this field include grinding process modeling, abrasives and grinding parameters, grinding process monitoring and control and realization of the software, the grinding mechanism and grinding damage on the surface, grinding force prediction, on-line detection, grinding on nanocoating material is a multivariable complex process.

scholarly journals Bushenhuoxue formula inhibits osteoclastogenesis and bone resorption on rabbit steroid-related osteonecrosis of the femoral head by suppressing NF-κB/NFATc1 pathway

2020 ◽  
Author(s):  
Peng Zhang ◽  
Songfeng Hu ◽  
Huihui Xu ◽  
Wenhua Yuan ◽  
Chenjie Xia ◽  
...  
Keyword(s):  
Femoral Head ◽  
Bone Resorption ◽  
Bearing Capacity ◽  
Weight Bearing ◽  
Enzyme Linked Immunosorbent Assay ◽  
Micro Ct ◽  
Model Group ◽  
Post Induction ◽  
Femoral Heads

Abstract Background: To investigate the effect and underlying mechanism of Bushenhuoxue formula (BSHXF) on steroid-related osteonecrosis of the femoral head (SONFH). Methods：Seventy-five male New Zealand white rabbits were divided into three groups: control group, model group and BSHXF group. Rabbit SONFH was induced by methylprednisolone (MPS) combined with lipopolysaccharide (LPS). At week 2 and 6 post induction, the corresponding number of rabbits were sacrificed, and the femoral heads were harvested for tissue analyses, including histopathology, mechanical test of femoral heads, micro-CT, tartrate-resistant acid phosphatase (TRAP) staining, immunohistochemistry for p-P65 and co-staining of TRAP and alkaline phosphatase (ALP). Additionally, the serum TRACP5b level was measured using enzyme-linked immunosorbent assay (ELISA). Meanwhile, we also evaluated the effect of BSHXF treatment on osteoclastogenesis in vitro. The protein level of cathepsin K (CTSK), P65, p-P65 and NFATc1 in rabbit femoral heads and RAW264.7 cells were detected, respectively.Results: At weeks 2 and 6 post induction, the elevated TRAP, p-P65 expression and reduced ALP expression were observed in the model group, with decreases in weight-bearing capacity of femoral heads and bone mass. After BSHXF treatment, the ratio of empty lacuna and the incidence of osteonecrosis in BSHXF group were markedly lower than that in model group. Micro-CT evaluation indicated that BSHXF has a preventive effect on bone loss in rabbit SONFH. In addition, BSHXF treatment increased weight-bearing capacity of femoral heads and reduced TRAP+ osteoclasts and serum TRACP5b level. Interestingly, CTSK, p-P65 and NFATc1 upregulation in necrotic femoral head could be reversed by BSHXF treatment, which also effectively inhibited RANKL-induced osteoclast differentiation and down-regulated CTSK, p-P65 and NFATc1 expression in vitro.Conclusions: BSHXF could inhibit osteoclastogenesis and bone resorption on rabbit steroid-related osteonecrosis of the femoral head by suppressing NF-κB/NFATc1 pathway.

Environmental Phase Stability of Next Generation Ceramic Composite for Hip Prostheses

2006 ◽  
Vol 309-311 ◽  
pp. 1223-1226 ◽  
Author(s):  
Giuseppe Pezzotti
Keyword(s):  
Residual Stress ◽  
Femoral Head ◽  
Stress Field ◽  
Optical Probe ◽  
Joint Surface ◽  
Material Surface ◽  
Residual Stress Field ◽  
Local Weight ◽  
Surface Degradation ◽  
Microscopic Evaluation

A hip-joint femoral head, made of alumina matrix composite, has been evaluated with respect to its surface degradation upon increasing elongation time in water vapor environment. A microscopic evaluation of surface degradation phenomena was obtained according to laser microprobe Raman and fluorescence spectroscopies. According to a confocal configuration of the optical probe, the spectroscopic assessments were performed in volumes limited to the very neighborhood of the material surface, thus minimizing the effect of the sub-surface, which was less affected by environmental degradation. Two main features were observed: (i) significant transformation of zirconia occurred in moist environment from the tetragonal to the monoclinic polymorph; such an environmentally induced phase transformation, conspicuously increased the fraction of monoclinic polymorph (i.e., ≅ 18 vol.% in average) already present in the as-received femoral head; (ii) the equilibrium residual stress field stored at the joint surface changed from a tensile field in the as-received material to a slightly compressive stress field after several hours aging in moist atmosphere and, after exposures >50 h to an increasingly tensile stress state. A residual stress field of tensile nature in the joint surface may trigger wear degradation in the femoral head in presence of microscopic (local) weight impingements due to micro-separation and third-body wear phenomena.

Modeling of Engineering Ceramics Grinding Surface Residual Stress

2013 ◽  
Vol 345 ◽  
pp. 281-284
Author(s):  
Wei Xiang Liu
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Plastic Region ◽  
Ceramic Materials ◽  
Source Model ◽  
Contact Length ◽  
Stress Generation ◽  
Maximum Temperature ◽  
Transient Temperature ◽  
Surface Residual Stress

Because of hard and brittle properties of ceramic materials, grinding and polishing the surface is the main processing methods, after grinded and polished, ceramics surface appear residual stresses and resulting in the cracks. Ceramic grinding surface residual stress are caused by machinery and thermal stress, residual stress generation mechanism is due to the combined effection under various stress, the workpiece transient temperature field can be calculated by triangle moving heat source model, the stress-strain relationship can be carried out in plastic region. according to the relationship between displacement increment and strain increment, can calculate element strain rate,in strong grinding, due to heat transfer time increases and the contact arc length increases, the maximum temperature is proportional to the available between the unit width and grinding ratio contact length, two regression method is used in study the effect of grinding parameters on surface residual stresses.

TEM investigations of surface residual stress relaxation in A12O3 and Al2O3-SiC nanocomposite

1994 ◽  
Vol 52 ◽  
pp. 628-629
Author(s):  
J. Fang ◽  
H. M. Chan ◽  
M. P. Harmer
Keyword(s):  
Residual Stress ◽  
Single Phase ◽  
Stress Relief ◽  
Stress Recovery ◽  
Surface Residual Stress ◽  
Microscopic Mechanism ◽  
Sic Particles ◽  
Annealing Procedure ◽  
The Difference ◽  
Nano Size

It was Niihara et al. who first discovered that the fracture strength of Al2O3 can be increased by incorporating as little as 5 vol.% of nano-size SiC particles (>1000 MPa), and that the strength would be improved further by a simple annealing procedure (>1500 MPa). This discovery has stimulated intense interest on Al2O3/SiC nanocomposites. Recent indentation studies by Fang et al. have shown that residual stress relief was more difficult in the nanocomposite than in pure Al2O3. In the present work, TEM was employed to investigate the microscopic mechanism(s) for the difference in the residual stress recovery in these two materials.Bulk samples of hot-pressed single phase Al2O3, and Al2O3 containing 5 vol.% 0.15 μm SiC particles were simultaneously polished with 15 μm diamond compound. Each sample was cut into two pieces, one of which was subsequently annealed at 1300° for 2 hours in flowing argon. Disks of 3 mm in diameter were cut from bulk samples.

Holding Power of Orthopaedic Screws in Bovine Femoral Heads

1993 ◽  
Vol 06 (03) ◽  
pp. 160-162 ◽  
Author(s):  
M. J. Ulm ◽  
D. G. Wilson
Keyword(s):  
Femoral Head ◽  
Cannulated Screws ◽  
Cancellous Screw ◽  
Holding Power ◽  
Cortical Screw ◽  
Femoral Heads ◽  
Cancellous Screws ◽  
Physeal Fractures

SummaryFemoral capital physeal fractures have been successfully repaired using 7.0 mm cannulated screws. The holding power of 7.0 mm cannulated screws was compared to the holding power of 5.5 mm cortical screws and 6.5 mm cancellous screws using paired bovine femoral heads. The 7.0 mm cannulated screw’s holding power was superior to the 6.5 mm cancellous screw and similar to that of the 5.5 mm cortical screw.When placed in the bovine femoral head, 7.0 mm cannulated screws have holding power greater than 6.5 mm cancellous screws and similar to 5.5 mm cortical screws.

Chalcones: As potent α-amylase enzyme inhibitors; synthesis, in vitro, and in silico studies

2020 ◽  
Vol 16 ◽  
Author(s):  
Mahboob Ali ◽  
Momin Khan ◽  
Khair Zaman ◽  
Abdul Wadood ◽  
Maryam Iqbal ◽  
...  
Keyword(s):  
In Silico ◽  
Enzyme Inhibitors ◽  
Biological Activities ◽  
Condensation Reaction ◽  
Type Ii Diabetes Mellitus ◽  
Spectroscopic Techniques ◽  
Chalcone Derivatives ◽  
In Silico Studies ◽  
Wide Range

: Background: The inhibition of α-amylase enzyme is one of the best therapeutic approach for the management of type II diabetes mellitus. Chalcone possesses a wide range of biological activities. Objective: In the current study chalcone derivatives (1-17) were synthesized and evaluated their inhibitory potential against α-amylase enzyme. Method: For that purpose, a library of substituted (E)-1-(naphthalene-2-yl)-3-phenylprop-2-en-1-ones was synthesized by ClaisenSchmidt condensation reaction of 2-acetonaphthanone and substituted aryl benzaldehyde in the presence of base and characterized via different spectroscopic techniques such as EI-MS, HREI-MS, 1H-, and 13C-NMR. Results: Sixteen synthetic chalcones were evaluated for in vitro porcine pancreatic α-amylase inhibition. All the chalcones demonstrated good inhibitory activities in the range of IC50 = 1.25 ± 1.05 to 2.40 ± 0.09 μM as compared to the standard commercial drug acarbose (IC50 = 1.34 ± 0.3 μM). Conclusion: Chalcone derivatives (1-17) were synthesized, characterized, and evaluated for their α-amylase inhibition. SAR revealed that electron donating groups in the phenyl ring have more influence on enzyme inhibition. However, to insight the participation of different substituents in the chalcones on the binding interactions with the α-amylase enzyme, in silico (computer simulation) molecular modeling analyses were carried out.

scholarly journals Synthesis, characterization, and pharmacological evaluation of thiourea derivatives

2020 ◽  
Vol 18 (1) ◽  
pp. 764-777
Author(s):  
Sumaira Naz ◽  
Muhammad Zahoor ◽  
Muhammad Naveed Umar ◽  
Saad Alghamdi ◽  
Muhammad Umar Khayam Sahibzada ◽  
...  
Keyword(s):  
Spectroscopic Techniques ◽  
Organosulfur Compounds ◽  
Bacterial Strains ◽  
Thiourea Derivatives ◽  
Toxicological Effects ◽  
Pharmaceutical Industries ◽  
Uv Visible ◽  
Hematological And Biochemical Parameters

AbstractThioureas and their derivatives are organosulfur compounds having applications in numerous fields such as organic synthesis and pharmaceutical industries. Symmetric thiourea derivatives were synthesized by the reaction of various anilines with CS2. The synthesized compounds were characterized using the UV-visible and nuclear magnetic resonance (NMR) spectroscopic techniques. The compounds were screened for in vitro inhibition of α-amylase, α-glucosidase, acetylcholinesterase (AChE), and butyrylcholinesterase (BuChE) enzymes and for their antibacterial and antioxidant potentials. These compounds were fed to Swiss male albino mice to evaluate their toxicological effects and potential to inhibit glucose-6-phosphatase (G6Pase) inhibition. The antibacterial studies revealed that compound 4 was more active against the selected bacterial strains. Compound 1 was more active against 2,2-diphenyl-1-picrylhydrazyl and 2,2’-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) free radicals, AChE, BuChE, and α-glucosidase. Compound 2 was more potent against α-amylase and G6Pase. Toxicity studies showed that compound 4 is safe as it exerted no toxic effect on any of the hematological and biochemical parameters or on liver histology of the experimental animals at any studied dose rate. The synthesized compounds showed promising antibacterial and antioxidant potential and were very active (both in vitro and in vivo) against G6Pase and moderately active against the other selected enzymes used in this study.

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