Analysis of Thermal Stability of CrCN Coatings Deposited on Nitrided Substrates Using Modulated Temperature Thermodilatometry

The aim of the research was to investigate the influence of nitriding of the substrate made of 42CrMo4 steel on thermal stability of the antiwear CrCN coating deposited on its surface using Cathodic Arc Evaporation method. Samples of non-nitrided and nitrided substrate/CrCN coating systems were tested with Modulated Temperature Thermodilatometry, which program included system annealing in 26 h, temperature of 290°C and argon atmosphere. Recorded during tests, changes in substrate elongation in response for changes of sample temperature, enabled qualitative determination of changes in stress states in the coatings as a result of samples annealing. Annealing of the system with nitrided substrate resulted in smaller change in residual stress in coating than for the system with non-nitrided substrate, which can indicate its better thermal stability. Values of residual stresses in coatings calculated by sin2ψ method before and after annealing on the basis of tests performed using X-Ray diffraction, agree with results of dilatometric tests

Reliability of the Epworth Sleepiness Scale and the Berlin Questionnaire for screening obstructive sleep apnea syndrome in the context of the examination of candidates for drivers

Background: The aim of the study has been to assess the usefulness of the Epworth Sleepiness Scale (ESS) and the Berlin Questionnaire (BQ) for obstructive sleep apnea syndrome (OSAS) screening. The capacity of both tests to discriminate between healthy individuals or with mild OSAS (apnea-hypopnea index (AHI) 0.05). Sensitivity of the ESS and BQ was 53.2% and 93.1%, respectively while specificity was 58.8% and 16.2%, respectively. Poor correlation between the ESS score and AHI and apnea index were noticed (r = 0.22, p = 0.001 and r = 0.24, p < 0.001, respectively). Conclusions: Considering its low sensitivity, the ESS should not be used as a screening test for the OSAS diagnosis amongst candidates for drivers. The BQ is characterised by high sensitivity for the OSAS diagnosis with AHI ≥ 15/h, however, due to low specificity, the questionnaire may increase the number of healthy individuals referred for needless diagnostic procedures. Med Pr 2016;67(6):721–72