scholarly journals Does Metal Transfer Differ on Retrieved Ceramic and CoCr Femoral Heads?

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Eliza K. Fredette ◽  
Daniel W. MacDonald ◽  
Richard J. Underwood ◽  
Antonia F. Chen ◽  
Michael A. Mont ◽  
...  
Keyword(s):  
Surface Area ◽  
Metal Transfer ◽  
Wear Testing ◽  
Median Surface ◽  
Arc Length ◽  
Visual Evidence ◽  
Femoral Heads ◽  
Bearing Materials ◽  
Pin On Disk

Metal transfer has been observed on retrieved THA femoral heads for both CoCr and ceramic bearing materials.In vitrowear testing has shown increased wear to polyethylene acetabular liners with the presence of metal transfer. This study sought to investigate the extent of metal transfer on the bearing surface of CoCr and ceramic femoral heads and identify prevalent morphologies. Three bearing couple cohorts: M-PE (n=50), C-PE (n=35), and C-C (n=15), were derived from two previously matched collections (n=50/group) of CoCr and ceramic femoral heads. From the three cohorts, 75% of the femoral heads showed visual evidence of metal transfer. These femoral heads were analyzed using direct measurement, digital photogrammetry, and white light interferometry. Surface area coverage and curved median surface area were similar among the three cohorts. The most prevalent metal transfer patterns observed were random stripes (n=21/75), longitudinal stripes (n=17/75), and random patches (n=13/75). Metal transfer arc length was shorter in the M-PE cohort. Understanding the morphology of metal transfer may be useful for more realistic recreation of metal transfer inin vitropin-on-disk and joint simulators studies.

A New Ortho-POD Biotribometer for Orthopaedic Biomaterials Wear Testing

2013 ◽  
Vol 461 ◽  
pp. 367-372
Author(s):  
Zi Kai Hua ◽  
Yong Wei Fan
Keyword(s):  
Heating System ◽  
Wear Testing ◽  
Variable Load ◽  
Wear Properties ◽  
Wide Range ◽  
Pin On Disk ◽  
Long Term Performance ◽  
Frequency Controller ◽  
Term Performance

Wear has been the primary failure mode affecting the long-term performance of orthopaedic implants. The tribological evaluation of orthopaedic biomaterials in vitro is regarded as an essential material characterization before implantation. In this paper, a new biotribometer of pin-on-disk type, the Ortho-POD, was designed and built for the biotribological tests of orthopaedic biomaterials. The primary goal of developing this Ortho-POD is to simulate and predict the wear properties of orthopaedic biomaterials in clinical application, especially in the form of hip, knee and spine prostheses. This 6-station Ortho-POD, including a pin guiding module, a motion module, a framework module and a loading module, provides multidirectional slide track shapes and variable load via a computer-controlled programmer. A frequency controller and heating system were assembled in the Ortho-POD so as to offer a wide range of testing conditions. Keywords-biotribology; wear; orthopaedic biomaterial; pin on disk; wear testing

In Vitro Wear Testing of Conventional Versus Sequentially Cross-Linked Polyethylene Liners in Combination with Different Sizes of Ceramic Femoral Heads

2012 ◽  
pp. 33-39 ◽  
Author(s):  
Carmen Zietz ◽  
Andreas Fritsche ◽  
Lars Middelborg ◽  
Wolfram Mittelmeier ◽  
Rainer Bader
Keyword(s):  
Wear Testing ◽  
Femoral Heads

scholarly journals Wear Simulation of Ceramic-on-Crosslinked Polyethylene Hip Prostheses: A New Non-Oxide Silicon Nitride versus the Gold Standard Composite Oxide Ceramic Femoral Heads

Materials ◽  
2020 ◽  
Vol 13 (13) ◽  
pp. 2917 ◽  
Author(s):  
Makiko Yorifuji ◽  
Saverio Affatato ◽  
Toshiyuki Tateiwa ◽  
Yasuhito Takahashi ◽  
Takaaki Shishido ◽  
...  
Keyword(s):  
Vitamin E ◽  
Silicon Nitride ◽  
Gold Standard ◽  
Wear Behavior ◽  
Wear Testing ◽  
Oxide Ceramic ◽  
Silica Layer ◽  
Wear Rates ◽  
Femoral Heads

The purpose of the present study was to compare the wear behavior of ceramic-on-vitamin-E-diffused crosslinked polyethylene (Vit-E XLPE) hip bearings employing the gold standard oxide ceramic, zirconia (ZrO2)-toughened alumina (Al2O3) (ZTA, BIOLOX®delta) and a new non-oxide ceramic, silicon nitride (Si3N4, MC2®). In vitro wear test was performed using a 12-station hip joint simulator. The test was carried out by applying the kinematic inputs and outputs as recommended by ISO 14242-1:2012. Vitamin-E-diffused crosslinked polyethylene (Vit-E XLPE) acetabular liners (E1®) were coupled with Ø28-mm ZTA and Si3N4 femoral heads. XLPE liner weight loss over 5 million cycles (Mc) of testing was compared between the two different bearing couples. Surface topography, phase contents, and residual stresses were analyzed by contact profilometer and Raman microspectroscopy. Vit-E XLPE liners coupled with Si3N4 heads produced slightly lower wear rates than identical liners with ZTA heads. The mean wear rates (corrected for fluid absorption) of liners coupled with ZTA and Si3N4 heads were 0.53 ± 0.24 and 0.49 ± 0.23 mg/Mc after 5 Mc of simulated gait, respectively. However, after wear testing, the ZTA heads retained a smoother topography and showed fewer surface stresses than the Si3N4 ones. Note that no statistically significant differences were found in the above comparisons. This study suggests that the tribochemically formed soft silica layer on the Si3N4 heads may have reduced friction and slightly lowered the wear of the Vit-E XLPE liners. Considering also that the toughness of Si3N4 is superior to ZTA, the present wear data represent positive news in the future development of long-lasting hip components.

scholarly journals Simple Equations Pertaining to the Particle Number and Surface Area of Metallic, Polymeric, Lipidic and Vesicular Nanocarriers

2021 ◽  
Vol 89 (2) ◽  
pp. 15
Author(s):  
M. R. Mozafari ◽  
E. Mazaheri ◽  
K. Dormiani
Keyword(s):  
Drug Delivery ◽  
Surface Area ◽  
Particle Number ◽  
Analytical Techniques ◽  
Metallic Particles ◽  
Nutraceutical Compounds ◽  
Mathematical Formulas ◽  
Simple Equations

Introduction: Bioactive encapsulation and drug delivery systems have already found their way to the market as efficient therapeutics to combat infections, viral diseases and different types of cancer. The fields of food fortification, nutraceutical supplementation and cosmeceuticals have also been getting the benefit of encapsulation technologies. Aim: Successful formulation of such therapeutic and nutraceutical compounds requires thorough analysis and assessment of certain characteristics including particle number and surface area without the need to employ sophisticated analytical techniques. Solution: Here we present simple mathematical formulas and equations used in the research and development of drug delivery and controlled release systems employed for bioactive encapsulation and targeting the sites of infection and cancer in vitro and in vivo. Systems covered in this entry include lipidic vesicles, polymeric capsules, metallic particles as well as surfactant- and tocopherol-based micro- and nanocarriers.

scholarly journals Newly Emerging Airborne Pollutants: Current Knowledge of Health Impact of Micro and Nanoplastics

2021 ◽  
Vol 18 (6) ◽  
pp. 2997
Author(s):  
Alessio Facciolà ◽  
Giuseppa Visalli ◽  
Marianna Pruiti Ciarello ◽  
Angela Di Pietro
Keyword(s):  
Surface Area ◽  
Current Knowledge ◽  
Oxidative Degradation ◽  
Health Impact ◽  
Outdoor Exposure ◽  
Environmental Matrices ◽  
Potential Health ◽  
Bodily Fluids

Plastics are ubiquitous persistent pollutants, forming the most representative material of the Anthropocene. In the environment, they undergo wear and tear (i.e., mechanical fragmentation, and slow photo and thermo-oxidative degradation) forming secondary microplastics (MPs). Further fragmentation of primary and secondary MPs results in nanoplastics (NPs). To assess potential health damage due to human exposure to airborne MPs and NPs, we summarize the evidence collected to date that, however, has almost completely focused on monitoring and the effects of airborne MPs. Only in vivo and in vitro studies have assessed the toxicity of NPs, and a standardized method for their analysis in environmental matrices is still missing. The main sources of indoor and outdoor exposure to these pollutants include synthetic textile fibers, rubber tires, upholstery and household furniture, and landfills. Although both MPs and NPs can reach the alveolar surface, the latter can pass into the bloodstream, overcoming the pulmonary epithelial barrier. Despite the low reactivity, the number of surface area atoms per unit mass is high in MPs and NPs, greatly enhancing the surface area for chemical reactions with bodily fluids and tissue in direct contact. This is proven in polyvinyl chloride (PVC) and flock workers, who are prone to persistent inflammatory stimulation, leading to pulmonary fibrosis or even carcinogenesis.

Effects of fetal corticosteroid treatments on postnatal surfactant function in preterm lambs

1995 ◽  
Vol 79 (3) ◽  
pp. 846-851 ◽  
Author(s):  
T. Ueda ◽  
M. Ikegami ◽  
D. Polk ◽  
K. Mizuno ◽  
A. Jobe
Keyword(s):  
Surface Area ◽  
Dynamic Compliance ◽  
Alveolar Space ◽  
Prenatal Treatment ◽  
Ultrasound Guided ◽  
Functional Characteristics ◽  
Arterial Pco2 ◽  
Alveolar Surfactant ◽  
Pool Sizes

Effects of prenatal corticosteroid on the properties of surfactant have not previously been evaluated. A single ultrasound-guided fetal injection with 0.5 mg/kg betamethasone 48 h before delivery of preterm lambs at 134- to 135-days gestation improved oxygenation, lowered the ventilatory pressures required to maintain arterial PCO2 between 30 and 40 Torr and decreased the protein leak of albumin from the intravascular to the alveolar space. This dose of glucocorticoid did not alter surfactant-saturated phosphatidylcholine pool sizes in the airspaces of preterm lambs. However, the treatment changed the characteristics of the surfactant recovered from the ventilated preterm lambs. The in vitro conversion from heavy to light subtype surfactant decreased from 59% for the saline-treated lambs to 37% for the corticosteroid-treated lambs after 180 min of surface area cycling (P < 0.02). Surfactant from the corticosteroid-treated lambs also increased the dynamic compliance of preterm surfactant-deficient rabbits more than did surfactant from the saline-treated lambs (P < 0.05). Prenatal treatment of preterm lambs with betamethasone improved the functional characteristics of surfactant without significant effects on the alveolar surfactant pool sizes.

Transport of L-proline and alpha-methyl-D-glucoside by chicken proximal cecum during development

1991 ◽  
Vol 260 (3) ◽  
pp. G457-G463 ◽  
Author(s):  
M. Moreto ◽  
C. Amat ◽  
A. Puchal ◽  
R. K. Buddington ◽  
J. M. Planas
Keyword(s):  
Surface Area ◽  
Transport Systems ◽  
Independent System ◽  
Passive Components ◽  
Sugar Absorption ◽  
Carrier Mediated Transport ◽  
Lower Capacity ◽  
Nominal Surface ◽  
Passive Influx

We examined the characteristics of amino acid and sugar absorption by the proximal cecum (PC) of chickens during posthatch development. Rates of absorption of L-proline (Pro) and alpha-methyl-D-glucoside (MG) were measured at 2 days, 5 wk, and 13 wk after hatch with an in vitro everted-sleeve method. For each age, pieces of PC and midjejunum were incubated in solutions containing 0.1-50 mM Pro or MG, and the active and passive components of Pro and MG absorption were determined. Five conclusions may be stated. 1) There are two carrier-mediated transport systems for Pro in the PC: a higher capacity Na(+)-dependent system (Vmax between 1.6 and 3.2 nmol.mg-1.min-1), and a lower capacity Na(+)-independent system (Vmax 0.3-0.8 nmol.mg-1.min-1). 2) Whereas both Pro transport systems are present in the PC at 5 and 13 wk, only the Na(+)-dependent system was found at 2 days. Although rates of transport per milligram tissue by the Na(+)-dependent system fell during development, when rates were normalized to nominal surface area, Vmax was significantly higher in the 5-wk-old group than in the other groups. 3) MG transport is by a Na(+)-dependent system. Vmax values (nmol.mg-1.min-1) were 0.32 (2 days), less than 0.43 (5 wk), and = 0.55 (13 wk). These differences were not affected by normalization to surface area. 4) Because at physiological concentrations passive influx of Pro and MG would be negligible, absorption of amino acids and sugars by the PC would be dependent on the presence of carrier-mediated systems.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Degradation of surfactant-associated protein B (SP-B) during in vitro conversion of large to small surfactant aggregates

1993 ◽  
Vol 295 (1) ◽  
pp. 141-147 ◽  
Author(s):  
R A W Veldhuizen ◽  
K Inchley ◽  
S A Hearn ◽  
J F Lewis ◽  
F Possmayer
Keyword(s):  
Surface Area ◽  
Sucrose Gradient ◽  
Gradient Centrifugation ◽  
Sucrose Gradient Centrifugation ◽  
Aggregate Fraction ◽  
Surfactant Aggregates ◽  
Morphological Studies ◽  
Surface Active ◽  
Protein B

Pulmonary surfactant obtained from lung lavages can be separated by differential centrifugation into two distinct subfractions known as large surfactant aggregates and small surfactant aggregates. The large-aggregate fraction is the precursor of the small-aggregate fraction. The ratio of the small non-surface-active to large surface-active surfactant aggregates increases after birth and in several types of lung injury. We have utilized an in vitro system, surface area cycling, to study the conversion of large into small aggregates. Small aggregates generated by surface area cycling were separated from large aggregates by centrifugation at 40,000 g for 15 min rather than by the normal sucrose gradient centrifugation. This new separation method was validated by morphological studies. Surface-tension-reducing activity of total surfactant extracts, as measured with a pulsating-bubble surfactometer, was impaired after surface area cycling. This impairment was related to the generation of small aggregates. Immunoblot analysis of large and small aggregates separated by sucrose gradient centrifugation revealed the presence of detectable amounts of surfactant-associated protein B (SP-B) in large aggregates but not in small aggregates. SP-A was detectable in both large and small aggregates. PAGE of cycled and non-cycled surfactant showed a reduction in SP-B after surface area cycling. We conclude that SP-B is degraded during the formation of small aggregates in vitro and that a change in surface area appears to be necessary for exposing SP-B to protease activity.

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