Preliminary experimental study on simultaneous polishing and shape setting of Nitinol wire

Abstract Separate processes for shape setting and polishing of Nitinol workpieces are well investigated in scientific literature and adopted industrially. However, a simultaneous process for shape setting and polishing of Nitinol has not yet been reported. In this study, preliminary results of such process are presented, providing insights and directions for further research on post-processing shape memory materials. For this purpose, Nitinol wire samples with phase transformation temperatures A f = 4.5 °C, A f = 31 °C and A f = 61 °C were plasma electrolytic polished (PEP) while fitted in a specially designed sample holder at three electrolyte temperatures t e = 50 °C, t e = 65 °C and t e = 80 °C. The PEP process duration was τ PEP = 60 s, τ PEP = 180 s and τ PEP = 300 s. After the PEP processes, the samples were investigated for the shape memory effect (SME). The training effect, known to be present in shape memory alloys (SMA), was taken into account. The surface roughness of the investigated wires was measured before and after the PEP process. The obtained results demonstrate that both a phase transformation temperature and an electrolyte temperature have a strong effect on polishing and shape setting results

Plasma Electrolytic Polishing of Porous Nitinol Structures

In this study, for the first time, the application of plasma electrolytic polishing (PEP) of porous Nitinol structures, mimicking a trabecular bone structure, that were additively manufactured, is reported. The cube-shaped samples were polished in a diagonal position three different times. The effect of PEP was evaluated in terms of the polishing depth, the effect on sample chemical composition and a possible shift of the phase transition temperature using microscopy, the energy dispersive X-ray spectroscopy (EDX), and the differential scanning calorimetry (DSC) techniques, respectively. The obtained results demonstrated that the PEP technique is suitable for polishing porous structures up to a certain depth into the sample inner structure and does not have any influence on the chemical composition and the phase transformation temperatures. However, small changes in the specific enthalpy were observable among the investigated samples. These changes could be attributed to the sample chemical inhomogeneity, measurement error, and/or differences in sample size and shape

Electrolyte optimisation for effective plasma electrolytic polishing of brass

Polishing of musical brass instruments is a very labour, material and time intensive process, with the main goal being to produce an instrument having very glossy surface. Here, plasma electrolytic polishing (PEP) could be applied, potentially increasing the efficiency of the manufacturing step. However, PEP of brass alloys is known to be challenging, since the use of unadapted electrolytes leads to the increase in surface roughness and/or reduced gloss of a part with increasing the PEP time. In this study, three different electrolytes developed for polishing brass CuZn28, were investigated at varying operational conditions. Namely, process time and applied voltage. The obtained experimental results demonstrate, that by selecting a suitable electrolyte, brass samples, can be successfully polished using the PEP technology with resulting surface smoothening from maximum value of Sq = 0.28μmto minimum value of Sq = 0.16μmfor the same sample and more than 21 time increased gloss at measurement angle of θ = 20°. It is also observed that the change in applied voltage has lower impact on the final sample gloss as it does on the final surface roughness. Finally, sample gloss does not change significantly by increasing the treatment time. However, depending on the electrolyte suitability, increase in PEP time might result in the increase or decrease of the final surface roughness

Plasma electrolytic polishing of nitinol

A novel, environmentally friendly, fast, and flexible polishing process for Nitinol parts is presented in this study. Nitinol samples with both superelastic and shape memory properties at room temperature were investigated. The chemical contamination and surface roughness of superelastic Nitinol plates were examined before and after plasma electrolytic polishing. The shift in phase transformation temperature and tensile strength before and after the polishing process were analysed using Nitinol wire with shape memory properties. The obtained experimental results were compared to the data obtained on reference samples examined in the as-received condition. It was found that plasma electrolytic polishing, when the right process parameters are applied, is capable of delivering Nitinol parts with extremely high surface quality. Moreover, it was experimentally proven that plasma electrolytic polishing does not have a negative impact on functionality or mechanical properties of polished parts

Lower Extremity Compartment Syndrome in National Football League Athletes.

BackgroundThe purpose of this study was to evaluate the incidence of lower extremity compartment syndrome in National Football League (NFL) athletes and report the mechanisms of injury, methods of treatment, and subsequent days missed. We review the existing literature on lower extremity compartment syndrome in athletic populations.HypothesisLower extremity compartment syndrome occurs with a low incidence in NFL athletes, and there is a high return-to-play rate after surgical management of acute compartment syndrome.Study designCase series.Level of evidenceLevel 4.MethodsA retrospective review of recorded cases of lower extremity compartment syndrome from 2000 to 2017 was performed using the NFL Injury Surveillance System and electronic medical record system. Epidemiological data, injury mechanism, rates of surgery, and days missed due to injury were recorded.ResultsDuring the study period, 22 cases of leg compartment syndrome in 21 athletes were recorded. Of these injuries, 50% occurred in games and 73% were the result of a direct impact to the leg. Concomitant tibial fracture was noted in only 2 cases (9.1%) and there was only 1 reported case of chronic exertional compartment syndrome. Surgery was documented in 15 of 22 cases (68.2%). For acute nonfracture cases, the average time missed due to injury was 24.2 days (range, 5-54 days), and all were able to return to full participation within the same season.ConclusionNFL athletes with acute leg compartment syndrome treated with surgery exhibited a high rate of return to play within the same season.Clinical relevanceAlthough compartment syndrome is a relatively rare diagnosis among NFL players, team physicians and athletic trainers must maintain a high index of suspicion to expediently diagnose and treat this potentially limb-threatening condition

Dual guidance structure for evaluation of patients with unclear diagnosis in centers for rare diseases (ZSE-DUO): study protocol for a controlled multi-center cohort study

Background In individuals suffering from a rare disease the diagnostic process and the confirmation of a final diagnosis often extends over many years. Factors contributing to delayed diagnosis include health care professionals' limited knowledge of rare diseases and frequent (co-)occurrence of mental disorders that may complicate and delay the diagnostic process. The ZSE-DUO study aims to assess the benefits of a combination of a physician focusing on somatic aspects with a mental health expert working side by side as a tandem in the diagnostic process. Study design This multi-center, prospective controlled study has a two-phase cohort design. Methods Two cohorts of 682 patients each are sequentially recruited from 11 university-based German Centers for Rare Diseases (CRD): the standard care cohort (control, somatic expertise only) and the innovative care cohort (experimental, combined somatic and mental health expertise). Individuals aged 12 years and older presenting with symptoms and signs which are not explained by current diagnoses will be included. Data will be collected prior to the first visit to the CRD’s outpatient clinic (T0), at the first visit (T1) and 12 months thereafter (T2). Outcomes Primary outcome is the percentage of patients with one or more confirmed diagnoses covering the symptomatic spectrum presented. Sample size is calculated to detect a 10 percent increase from 30% in standard care to 40% in the innovative dual expert cohort. Secondary outcomes are (a) time to diagnosis/diagnoses explaining the symptomatology; (b) proportion of patients successfully referred from CRD to standard care; (c) costs of diagnosis including incremental cost effectiveness ratios; (d) predictive value of screening instruments administered at T0 to identify patients with mental disorders; (e) patients’ quality of life and evaluation of care; and f) physicians’ satisfaction with the innovative care approach. Conclusions This is the first multi-center study to investigate the effects of a mental health specialist working in tandem with a somatic expert physician in CRDs. If this innovative approach proves successful, it will be made available on a larger scale nationally and promoted internationally. In the best case, ZSE-DUO can significantly shorten the time to diagnosis for a suspected rare disease