Friction between articulating surfaces cause temperature rise in the acetabular cup and femoral head. This heating may influence the rate of wear, fatigue, creep and oxidative degradation of bearing ...materials. The objective of this study is to determine the effect of surface patterning on frictional temperature rise of the articulating surfaces of vitamin E blended ultra-high molecular weight polyethylene acetabular component paired with a cobalt–chromium (CoCrMo) femoral component. For this reason concave dimples were formed on inner surface of the acetabular cup with 0.5mm diameter and 0.5mm depth. Temperature rise between the bearing surfaces was measured under different loading conditions. Frictional measurements of the joints were carried out on a custom made hip joint friction experimental set up. The prostheses were of 28mm diameter. Applied static loads were changed from 200N to 1500N. In the flexion–extension plane, a simple harmonic oscillatory motion between ±24° was applied to the ultra high molecular weight polyethylene acetabular component. The frequency of motion was 1Hz and the tests were run up to 11,000 cycles. Temperature rise in acetabular and femoral component was recorded with embedded thermocouples. Lower temperature rise in patterned sample pairs were measured than unpatterned samples. So it can be said that the surface patterning contributes to reduction of frictional heating of sliding surfaces.
•Surface dimples were machined on the inner surface of the acetabular cup samples.•Significant temperature rise was measured between acetabular cup and femoral head.•Surface patterning contributed to reduction of frictional heating on samples.•Temperature rise of UHMWPE and VE-UHMWPE samples were compared.•Lower temperature rise was measured for VE-UHMWPE than conventional UHMWPE.
•Temperature rise was measured between acetabular insert and femoral head.•Experiments were conducted with a custom made hip joint friction simulator.•Temperature rise of UHMWPE was theoretically ...calculated.•Theoretical and experimental results were comparable.•Lower temperature rise was measured for VE-UHMWPE than conventional UHMWPE.
Frictional heating of articulating surfaces may influence the rate of wear, fatigue, creep and oxidative degradation of bearing materials. Also temperature rise can damage the surrounding tissue and lubricant around the artificial joint and contributes insert loosening. The objective of this study is to determine temperature rise between sliding surface of vitamin E blended UHMWPE and conventional UHMWPE acetabular component paired with a cobalt–chromium–molybdenum (CoCrMo) femoral component, as a function of sliding time and applied load. Besides the experimental studies, the frictional temperature rise of conventional UHMWPE was theoretically calculated. Frictional measurements of the joints were carried out on a custom made hip joint friction simulator. The diameter of the prostheses was 28mm. Applied static loads were changed from 200N to 1500N. In flexion–extension plane, a simple harmonic oscillatory motion between ±24° was applied to the UHMWPE acetabular component. The period of motion was 1Hz and the tests were run up to 11,000 cycles. Temperature rise in acetabular and femoral component was recorded with embedded thermocouples. Both the experimental temperature rise values and theoretical calculations results were compared and evaluated.
Porous and biodegradable hyaluronic acid (HA) nanogel and their copolymeric forms with sucrose (Suc), HA:Sucrose (HA:Suc) nanogels, were synthesized by employing glycerol diglycidyl ether (GDE) as ...crosslinker with a single step reaction in surfactant-free medium. The size of the nanogels was determined as 150 ± 50 nm in dried state from SEM images and found to increase to about 540 ± 47 nm in DI water measured with DLS measurements. The surface areas of HA and HA:Suc nanogels were measured as 18.07 ± 2.4 and 32.30 ± 6.1 m2/g with porosities of 3.58 ± 1.8, and 9.44 ± 3.1 nm via BET analysis, respectively. The zeta potentials for HA and HA:Suc nanogels were measured as −33 ± 1.4 and − 30 ± 1.2 mV, respectively. The thermal degradation of both types of nanogels revealed similar trends, while hydrolytic degradation of the nanogels was about 22.7 ± 0.2 wt% in 15 days. Both HA and HA:Suc nanogels were stable in blood up to 250 μg/mL concentration with approximately 0.5 ± 0.1% hemolysis ratio and 76 ± 12% blood clotting indices, respectively. Finally, these nanogels were used as a sustained slow-release or long-term delivery system over 2 days for a hydrophobic cancer drug, 3‑((E)‑3‑(4‑hydroxyphenyl)acryloyl)‑2H‑chromen‑2‑on (A#) established by our group. The nanogels successfully delivered the model drug A at 10.43 ± 2.12 mg/g for 2 days.
•Facile synthesis of HA and HA:Suc nanogels in a surfactant free environment with high yield•HA based nanogels with few hundred nm sizes, irregular shaped, mesoporous structure•HA:Suc nanogels as biodegradable, blood compatible and cancer drug delivery device
The aim of this study was to evaluate the feasibility of off-pump coronary artery bypass grafting combined with radiofrequency ablation and to compare outcomes between patients with permanent and ...paroxysmal atrial fibrillation (AF) in terms of restoring sinus rhythm.
Thirty-three patients underwent the combined procedure. Mean age was 62.34 +/- 8.20 years; there were 12 female and 21 male patients. Twenty-one patients were diagnosed as permanent AF (group A) and 12 had paroxysmal AF (group B). After the off-pump revascularization patients underwent pulmonary vein ablation. Rhythm was evaluated at discharge and at 6 and 12 months' follow-up. Patients in stable sinus rhythm underwent transthoracic echocardiographic examination to evaluate atrial contractility at 6 and 12 months.
There was no operative mortality or major complications. The mean ablation time was 11 +/- 3.4 minutes, including multiple applications. At the end of the procedure 84.5% of patients were free of AF. Sinus rhythm was established in 56% (group A, 52%; group B, 58.3%), 70.5% (group A, 58%; group B, 83.3%), and 71% (group A, 59%; group B, 83.3%) of patients at discharge and at 6 and 12 months, respectively (p = 0.249). Biatrial contractility was detected in 71% of group A and 76% of group B patients at 6 months' follow-up. More patients in group A returned to AF during follow-up when compared with group B (p = 0.016). Female sex (odds ratio, 2.1), chronic lung disease (odds ratio, 1.40), left ventricular disfunction (p = 0.016), and hypertension (odds ratio, 2.57) emerged as risk factors for AF recurrence after ablation.
Concomitant off-pump coronary artery bypass grafting and bipolar radiofrequency ablation was safe and effective. These patients should be considered for adjunctive treatment at the time of off-pump revascularization.
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