A study on the effect of the clearance on the contact stress and kinematics of polymeric composite journal bearings

In this article the effect of the clearance on the contact stress and kinematics of a polymeric composite journal bearing is investigated. To this purpose a test rig is devised, which is capable to measure the tribological characteristics of the large-scale composite bearings. The kinematics of the setup is simulated by a 2D FEM model. Moreover, to evaluate the contact area between the bearing and the shaft, pressure indicator films are used and a simplified 3D model is provided. Simulation results correspond closely to the experimental data, and it is shown that the clearance variation can have a big impact on the contact stress distribution

Optimization of PET protocol and interrater reliability of 18F-PSMA-11 imaging of prostate cancer

Background Several scan parameters for PET imaging with F-18-PSMA-11 such as dosage, acquisition time and scan duration were evaluated to determine the most appropriate scan protocol, as well as the effect of furosemide administration on lesion visualization. Forty-four patients were randomly assigned to a dosage group (2.0 +/- 0.2 or 4.0 +/- 0.4 MBq/kg F-18-PSMA-11). All patients received a full-body PET/CT 1 h and 3 h after radiotracer injection with a scan duration of 3 min/bed position. For comparison of the scan duration, images were reconstructed for 1.5 and 3 min/bed position. Patients were intravenously administered 0.5 mg/kg furosemide with a maximum dose of 40 mg. To evaluate the furosemide effect, 22 additional patients were recruited and received one full-body PET/CT 1 h after administration of 2.0 +/- 0.2 MBq/kg F-18-PSMA-11 with a scan duration of 3 min/bed position. To this group, no furosemide was administered. Images were scored on image quality using a 7-point scale and each suspicious lesion was described. To assess interrater reliability, two nuclear physicians scored all scans independently and described all observed suspicious lesions. Results The 4 MBq/kg group received for all reconstructed images (60 min p.i., 1.5 and 3 min/bed position and 180 min p.i., 1.5 and 3 min/bed position) the highest median image quality score compared to the 2 MBq/kg group (p values < 0.01). When comparing all reconstructed images, the highest image quality score was given to images at 60 min p.i., 3 min/bed position for both dosage groups (score 5 and 6 for 2 and 4 MBq/kg, respectively). The addition of furosemide administration decreased the interference score with one point (p = 0.01106) and facilitated the evaluation of lesions in proximity to the ureters. The interrater reliability for the comparison of each lesion separately after more than 40 F-18-PSMA-11 scan readings showed an increasing kappa value from 0.78 (95% CI, 0.65-0.92) to 0.94 (95% CI, 0.87-1). Conclusion Although the results indicate an administered activity of 4.0 +/- 0.4 MBq/kg, preference will be given to 2.0 +/- 0.2 MBq/kg due to the small difference in absolute score (max 1 point) and the ALARA principle. For evaluation of lesions in proximity to the ureters, the co-administration of a diuretic can be useful. The increase of the kappa value from 0.78 to 0.94 suggests a learning curve in the interpretation of F-18-PSMA-11 images

Wear investigation of wet clutch friction material

Wear of friction plates for wet clutch applications can result in a decreasing transmittable torque and the occurrence of vibrations throughout the entire drive chain causing loss of performance and discomfort. The need for a simple wear model exists to predict the lifetime of the clutch and to give an insight in the combined influence of the operational parameters such as pressure and speed. In this paper wear of paper-based friction material is investigated on a simplified SAE#2 test-rig using only one friction plate and one spacer plate. During engagement torque, applied pressure and sliding velocity are continuously monitored. After a set number of engagement cycles the thickness change of the friction plate is measured and surface topography of the spacer plate is registered. Based on Archard’s wear law a specific wear rate is derived

Adjuvant radiotherapy after radical cystectomy for patients with muscle invasive bladder cancer : a phase II trial

Background: Neo-adjuvant chemotherapy followed by radical cystectomy with extended pelvic lymph node dissection is considered to be the treatment of choice for patients with muscle invasive bladder cancer (MIBC). Despite this aggressive treatment the outcome is poor and ultimately, 30% of the patients with >= pT3 tumors develop a pelvic recurrence. We hypothesize that postoperative adjuvant external beam radiotherapy (EBRT) might prevent local and lymph node recurrence and improve disease free-and overall survival as loco-regional recurrence is linked to the development of distant metastasis. Methods: We plan to perform a multicentric prospective phase two study including 76 patients. Eligible patients are patients with MIBC, treated with radical cystectomy and presenting with >= 1 of the following characteristics: - Pathological (p) T3 stage + presence of lymphovascular invasion on pathological examination - pT4 stage - < 10 lymph nodes removed - positive lymph nodes - positive surgical margins Patients will have a F-18-FDG PET-CT to rule out the presence of distant metastasis prior to EBRT. A median dose of 50 Gy in 25 fractions is prescribed to the pelvic lymph node regions with inclusion of the operative bladder bed in case of a positive surgical margin. Patients with suspected lymph nodes on PET-CT can still be included in the trial, but a simultaneous integrated boost to 74Gy to the positive lymph nodes will be delivered. Blood and urine samples will be collected on day-1 and last day of EBRT for evaluation of biomarkers. The primary endpoint is evaluation of acute >= Grade 3 intestinal or grade 4 urinary toxicity, in case of a neo-bladder reconstruction, within 12 weeks after EBRT. Secondary endpoints are: assessment of QOL, late RTOG toxicity, local control, disease free survival and overall survival. Biomarkers in urine and blood will be correlated with secondary survival endpoints. Discussion: This is a prospective phase 2 trial re-assessing the feasibility of adjuvant radiotherapy in high-risk MIBC

How design quirks and conditions of use conspire to structural failure : a case study

Sometimes designers introduce a number of quirks in their design, either due to a preference for certain technologies or practices or under the influence of the policies in the companies they work for. While most of the time these quirks are harmless, sometimes they can, either in themselves or in combination with the conditions in which the design is used lead to failure. In this paper a case is discussed in which a designer used a quirky solution of lengthening an existing design of a 40ft. freight container to 45ft.. While the design in itself was not fundamentally flawed, it proved to be incompatible to the handling equipment still in use at most seaports

Early biomarkers related to secondary primary cancer risk in radiotherapy treated prostate cancer patients: IMRT versus IMAT

AbstractPurposeTo investigate whether rotational techniques (Volumetric Modulated Arc Therapy – VMAT) are associated with a higher risk for secondary primary malignancies compared to step-and-shoot Intensity Modulated Radiation Therapy (ss-IMRT). To this end, radiation therapy (RT) induced DNA double-strand-breaks and the resulting chromosomal damage were assessed in peripheral blood T-lymphocytes of prostate cancer (PCa) patients applying γH2AX foci and G0 micronucleus (MN) assays.Methods and materialsThe study comprised 33PCa patients. A blood sample was taken before start of therapy and after the 1st and 3rd RT fraction to determine respectively the RT-induced γH2AX foci and MN. The equivalent total body dose (DETB) was calculated based on treatment planning data.ResultsA linear dose response was obtained for γH2AX foci yields versus DETB while MN showed a linear-quadratic dose response. Patients treated with large volume (LV) VMAT show a significantly higher level of induced γH2AX foci and MN compared to IMRT and small volume (SV) VMAT (p<0.01). Assuming a linear-quadratic relationship, a satisfactory correlation was found between both endpoints (R2 0.86).ConclusionsBiomarker responses were governed by dose and irradiated volume of normal tissues. No significant differences between IMRT and rotational therapy inherent to the technique itself were observed

Polymers in tribology: challenges and opportunities

Seminal characteristics such as good corrosion resistance, self-lubrication ability and acceptable wear resistance have made polymer based materials to become popular in a wide and diverse range of tribological applications. Despite numerous applications and decades of research in polymer tribology, a considerable number of questions remain unsolved both regarding fundamental understanding and engineering design issues. One of the reasons is the vast number of different polymers and polymer based composites that are in use, but also the diversity in applications and the difficulties to observe the governing tribomechanisms. Material and component producers are often the only owners of composition and basic material characteristics. Thus, designers and application engineers are obviously forced to rely on catalogue information and scattered literature data. For that reason prior to application of a chosen material/component functional and tribological tests with scale models or laboratory set-ups are performed to obtain better confidence in the proposed design solutions. Each time again the definition of an adequate test program is of major concern. The present paper discusses some challenges related to the use and testing of polymer based tribocomponents such as bearings, sliders, gears, rollers, etc. Attention is not only given to basic influencing parameters such as contact load, sliding/rolling velocity, environmental conditions, mating surface conditions, etc. Also experimental strategies and advanced measuring techniques that allow to follow the dynamic nature of transfer film formation and wear are considered. Finally, actual trends in reinforcements (e.g. natural fibres) and lubricant additives (nanoparticles) are discussed together with opportunities for improved tribobehaviour

Misrepresentations and flawed logic about the prevalence of false memories

Brewin and Andrews (2016) propose that just 15% of people, or even fewer, are susceptible to false childhood memories. If this figure were true, then false memories would still be a serious problem. But the figure is higher than 15%. False memories occur even after a few short and low-pressure interviews, and with each successive interview they become richer, more compelling, and more likely to occur. It is therefore dangerously misleading to claim that the scientific data provide an “upper bound” on susceptibility to memory errors. We also raise concerns about the peer review process