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Machining difficult-to-cut materials involves challenging machining conditions, including higher temperatures in the cutting zone, cutting forces and friction. Another important phenomenon is vibration, which is undesirable when manufacturing high quality workpieces. One way to reduce vibration in the cutting zone is to use cooling methods. Due to its environmentally friendly nature, the minimum quantity lubrication (MQL) method has already been widely used in metalworking. However, when combined with nanofluids, it improves the ability of the aerosol to dissipate more heat and increase lubrication in the cutting zone. This paper presents the effect of a polyol esterbased Al2O3 nanofluid due to the varying mass concentration of nanoparticles on the vibration during turning of Ti6Al4V alloy and compares the results with dry cutting and the MQL method without nanoparticles. Four concentrations (0.25-1 wt%), variable nanofluid flow rate E=0.388-1.182 g/min and air flow rate P=10-40 l/min were considered. According to the statistical analysis, the most important factor influencing tool vibration was the mass concentration of nanoparticles in the cutting fluid. By combining the MQL method with 0.5 wt% Al2O3, the vibration acceleration RMS values were found to be the lowest. When compared to the MQL method without nanoparticles, the RMS values for dry cutting ranged from 17.8% to 24.9%, and for wet cutting they were reduced by about 10.9-18.5%. [ABSTRACT FROM AUTHOR]

In a placebo controlled double-blind study including 10 patients with heart failure the nisoldipine/digoxin interaction was studied. Nisoldipine was shown to elevate digoxin plasma concentrations significantly by about 15% (trough levels). During chronic combination therapy with nisoldipine trough levels and plasma concentrations 4 h after the morning dose of digoxin were 1.35 +/- 0.14 and 1.92 +/- 0.16 ng ml-1 respectively, whereas they averaged to 1.16 +/- 0.14 and 1.52 +/- 0.16 ng ml-1 with digoxin and placebo (P less than 0.05; mean +/- s.e. mean). Systolic time intervals were significantly altered by nisoldipine co-administration compared with digoxin plus placebo. In certain patients the elevation of digoxin plasma levels due to nisoldipine co-administration could be of clinical relevance. [ABSTRACT FROM AUTHOR]

Introduction: It is unclear whether it is possible to determine the training load on the basis of the 6-minute walk test (6-MWT) in patients after cardiac surgery with low tolerance of physical exercise., Aim: Use of the 6-MWT to determine an individual initial training load in walking training on a treadmill in the early phase of cardiac rehabilitation in men after coronary artery bypass graft (CABG) surgery., Material and Methods: Twenty-two men aged 54 to 74 years, up to 3 months after CABG surgery participated in walking training on a treadmill (12-15 sessions). Patients underwent the initial and final treadmill exercise stress test (TEST) and the 6-MWT. Based on 6-MWT results, the initial training load was prescribed. Before the 6-MWT and 3 minutes after its completion, lactate concentration was determined., Results: The 6-MWT distance increased from 420 ±80 m to 519 ±61 m ( p < 0.001), and the energy expenditure from 4.4 ±1.4 MET to 6.3 ±1.3 MET ( p < 0.001). There was a positive correlation between 6-MWT distance and energy expenditure in the TEST before rehabilitation ( r = 0.60, p = 0.005), and after rehabilitation ( r = 0.75, p < 0.001). A negative correlation was found between the baseline 6-MWT distance and distance increment in the final 6-MWT ( r = -0.66, p = 0.002). The 6-MWT did not induce hyperlactatemia., Conclusions: The 6-MWT can be used in exercise intensity prescription, especially for determining the individual initial training load, load progression, as well as its correction during follow-up tests., Competing Interests: The authors report no conflict of interest., (Copyright: © 2021 Polish Society of Cardiothoracic Surgeons (Polskie Towarzystwo KardioTorakochirurgów) and the editors of the Polish Journal of Cardio-Thoracic Surgery (Kardiochirurgia i Torakochirurgia Polska).)

Introduction: Walking training is a good alternative to the commonly used cycle ergometer training. It is still necessary to develop rehabilitation programs based on walking characterized by a high degree of safety and effectiveness., Aim: Application of continuous walking training as an alternative to interval cycle ergometer training in men after coronary artery bypass graft (CABG) surgery, using the 6-minute walk test (6-MWT) to determine the initial training load., Material and Methods: Forty-four men aged 45 to 76 years, up to 3 months after CABG surgery, were randomly assigned to continuous training on a treadmill (study group) or interval training on a cycle ergometer (control group), performed 6 times per week (12-15 sessions). Participants underwent the treadmill exercise stress test (TEST) and 6-MWT at the begining and after completion of the rehabilitation program. Before and 3 minutes after the 6 th and 12 th training session blood lactate concentration was determined., Results: Energy expenditure in TEST increased from 4.4 to 6.3 MET in the study group and from 5.0 to 6.5 MET in the control group. Distance walked in 6-MWT increased from 420 to 519 m and from 438 to 510 m, respectively. Resting heart rate (HR) and double product (DP) decreased only in the study group as well as systolic blood pressure (SBP), HR and DP at peak exercise load in baseline TEST. Mean energy expenditure during training sessions was 2.6 MET in the study group and 2.8 MET in the control group (NS). Exercise blood lactate concentration did not exceed 2.0 mmol/l in both groups., Conclusions: Both rehabilitation programs were of similar effectiveness and their intensity did not exceed the anaerobic threshold., Competing Interests: Authors report no conflict of interest., (Copyright © 2020 Polish Society of Cardiothoracic Surgeons (Polskie Towarzystwo KardioTorakochirurgów) and the editors of the Polish Journal of Cardio-Thoracic Surgery (Kardiochirurgia i Torakochirurgia Polska).)

Walking is regarded as one of the most common and utilitarian activities of everyday life. Rehabilitation programs developed on the basis of this form of activity often constitute the primary method of rehabilitating patients after coronary artery bypass grafting. This paper provides a review of literature concerning various forms of walking training, discussing their impact on the parameters of exercise capacity and verifying the training methods with regard to the current guidelines. Attention is drawn to the diversity of the exercise protocols applied during the early and late stages of rehabilitation and pre-rehabilitation programs including: treadmill walking, walking down the corridor, treadmill walking enriched with virtual reality, and walking as an element of training sessions consisting of many different forms of activities. Exercise protocols were also analyzed in terms of their safety, especially in the case of high-intensity interval training. Despite the variety of the available rehabilitation programs, the training methodology requires constant improvement, particularly in terms of load dosage and the supervision of training sessions.