Incomplete oxygen reduction gives rise to reactive oxygen species (ROS). For a long time they have been considered unwelcome companions of aerobic metabolism. Organisms using oxygen developed several systems of ROS scavenging with enzymatic and non enzymatic antioxidants, which allow them control the cellular level of oxygen derived from free radicals. It is well established nowadays that ROS are not necessarily negative byproducts, but they also play an important role in cellular mechanisms. They are involved in many regular cellular processes in all aerobic organisms. When the antioxidant system is overcome and the balance between ROS production and scavenging is disrupted, oxidative stress occurs. It has been reported that oxidative stress may be linked to some human diseases and is also involved in biotic and abiotic stress response in plants.

Buckling of the stiffened flange of a thin-walled member is reduced to the buckling analysis of the cantilever plate, elastically restrained against rotation, with the free edge stiffener, which is susceptible to deflection.Longitudinal stress variation is taken into account using a linear function and a 2nd degree parabola. Deflection functions for the plate and the stiffener, adopted in the study, made it possible to model boundary conditions and different buckling modes at the occurrence of longitudinal stress variation. Graphs of buckling coefficients are determined for different load distributions as a function of the elastic restraint coefficient and geometric details of the stiffener. Exemplary buckling modes are presented.

This study was carried out on the background of Sutong Bridge project based on fracture mechanics, aiming at analyzing the growth mechanism of fatigue cracks of a bridge under the load of vehicles. Stress intensity factor (SIF) can be calculated by various methods. Three steel plates with different kinds of cracks were taken as the samples in this study. With the combination of finite element analysis software ABAQUS and the J integral method, SIF values of the samples were calculated. After that, the extended finite element method in the simulation of fatigue crack growth was introduced, and the simulation of crack growth paths under different external loads was analyzed. At last, we took a partial model from the Sutong Bridge and supposed its two dangerous parts already had fine cracks; then simulative vehicle load was added onto the U-rib to predict crack growth paths using the extended finite element method.

Plants are continuously exposed to various environmental stresses and they respond to them in different ways. Ambient temperature is among the most important environmental cues that directly influence plant growth and yield. Research in recent years has revealed that epigenetic mechanisms play a key role in plants' response to temperature stress. Changes in gene expression evoked by stress signals follow post-translational histone modifications, DNA methylation, histone variant incorporation, and the action of chromatin remodeling factors and Polycomb group proteins. The majority of epigenetic modifications induced by temperature stress are reversible in nature; thus, chromatin returns to its previous state after the stress has passed. Some modifications seem stable, however, due presumably to so-called stress memory. Epigenetic modifications can be inherited through mitosis and meiosis. By dint of epigenetic memory, plants can more efficiently respond to future stressful conditions, thereby increasing their potential for environmental adaptation. Recognition of the epigenetic mechanisms that take part in plants' response to changes of ambient temperature will increase our understanding of adaptations to stress conditions.

Heavy metal pollution of soil is a significant environmental problem and has a negative impact on human health and agriculture. Phytoremediation can be an alternative environmental treatment technology, using the natural ability of plants to take up and accumulate pollutants or transform them. Proper development of plants in contaminated areas (e.g. heavy metals) requires them to generate the appropriate protective mechanisms against the toxic effects of these pollutants. This paper presents an overview of the physiological mechanisms of stress avoidance and tolerance by plants used in phytoremediation of heavy metals.

Endopolyploidy is a condition of a cell containing reduplicated genetic material in its nucleus. Cells with the nuclei of different ploidy levels are often present within a single polysomatic organism. Endoreduplication is thus a modified cell cycle that omits cytokinesis and leads to chromatin replication in the endopolyploid cells. This study aimed to research the effect of salinity on endopolyploidy of Trifolium pratense and T. repens. Both species are important pasture legumes and belong to the genus Fabaceae with the well documented endopolyploidy occurence. Endopolyploidy levels in the seedlings treated with 0, 30, 60, 90 and 120 mM NaCl were investigated by flow cytometry. The seedling organs were evaluated during three ontogeny stages. The cytometric data plotted on a histogram showed the presence of 2C-16C nuclei in T. pratense and 2C-8C in T. repens. The hypothesis that salinity induces additional endocycles was not confirmed. Our results show that the distribution of nuclei among ploidy levels does not differ markedly between the treatment groups and the control ones. Additionally, only minor changes were observed among the endoreduplication indexes (EI) of plant organs after exposure to various salt concentrations. Endopolyploidy patterns within the salt-treated seedlings during ontogeny are similar to the controls. We suggest that endopolyploidy in Trifolium species is a conserved genetic trait, rather than an adaptation to salinity stress. The analyses of the roots of T'. pratense at stage III show that with the increased concentrations of NaCl the length of roots decreased, but no evident changes in endopolyploidy occured.

We talk to Dr. Emilia Rejmak-Kozicka from the PAS Institute of Experimental Biology about how our bodies respond to chronic stress.

First psychological research at Arctowski station were conducted in 1979. In the nineties the American team under direction of prof. L. Palinkas conducted research in order to determine the patterns of multicultural psychosocial adaptation. The author discusses stress as a result of isolation and extreme conditions.

The brake linkage of a hoisting machine is a very important component determining the safety of

the hoisting machine’s entire braking system. It is subject to weekly inspections. However, an efficiency

test of brake performance is carried out every 6 months. Once every 3 years, a test must be carried out by

an appraiser who pays particular attention to the executive and control components of the brakes as well

as the strain - brake system and brake release components. The legal provisions regulating the testing

of braking system linkages are not precise. So far, the control has been based on random measurement

of strains using electrical resistance strain gauges stuck to the surface of the linkage. A new method

for measuring the strains of the linkage has been proposed in the work. It is based on fibre optic strain

sensors with Fibre Bragg Gratings (FBG). They are mounted using specially designed and tested holders

for mounting on the brake linkage. They provide quick assembly and the measurement of strain in the

direction parallel to the axis of the linkage. The structure of the holder also allows for the measurement

in 4 positions turned every 90 relative to one another. Such a measurement enables a comprehensive

analysis of strains and stresses in the brake linkage. In the work, it was shown that there is a complex

state of strain and stress in the brake linkage. The previous procedures for linkage testing are inadequate

in relation to this condition. An experimental and numerical method was proposed to assess the state

of linkage stress. It should constitute the basis for the decision of the appraiser to allow the linkage for

further use. The method proposed in the work also allows for continuous measurements of linkage strains

as well as dynamic braking tests.

Purpose: The aim of this paper is to discuss exposure to stress and the incidence of occupational burnout among oncology nurses.

Methods: To study the discussed issue, we analyzed six full-text research papers which were searchable by EBSCO and met all required criteria (words included in the abstract, English publication, size of the study group).

Results: Exposure to chronic occupational stress may lead to developing burnout syndrome. Social service professionals are especially affected as they are expected to be emotionally engaged in their jobs, which particularly applies to such health care professionals as nurses, psychologists, police officers and social workers. Because of occupational burnout work efficiency may deteriorate. Oncology nurses are among the most affected nurse groups in terms of exposure to the risk of burnout.

Conclusions: Oncology nurses as well as other oncology workers exhibit an increased risk and a higher grade of burnout. Psychological training sessions are available which effectively prevent and alleviate the effects of burnout.

The main aim of the study was to determine the goodness of fit between the relaxation function described with a rheological model and the real (experimental) relaxation curves obtained for digital materials fabricated with a Connex 350 printer using the PolyJet additive manufacturing technology. The study involved estimating the uncertainty of approximation of the parameters of the theoretical relaxation curve. The knowledge of digital materials is not yet sufficient; their properties are not so well-known as those of metallic alloys or plastics used as structural materials. Intensive research is thus required to find out more about their behavior in various conditions. From the calculation results, i.e. the uncertainty of approximation of the relaxation function parameters, it is evident that the experimental curves coincide with the curves obtained by means of the solid model when the approximation uncertainty is taken into account. This suggests that the assumed solid model is well-suited to describe a real material.

The paper concerns simulation of fully developed and axially-symmetrical turbulent flow of coarse-dispersive slurry if all solid particles have similar size and shape with particles diameter from 1 mm to 5 mm, solid density from 1045 kg/m^3 to 3000 kg/m^3, and solid concentration by volume from 20% to 40%. The author examines the influence of particle diameter on additional shear stress due to the ‘particles-wall’ interactions for moderate and high solid concentration. The mathematical model was developed using Bagnold's concept, [26] and assumes that the total wall shear stresses are equal to the sum of ‘liquid-wall’ and ‘particles-wall’ shear stresses. The mathematical model was successfully verified with own measurements of frictional head loss in vertical coarse - dispersive slurry flow, named: ‘sand-water’, ‘polystyrene-water’ and ‘pvc-water’, [10], [26]. The mathematical model can predict ‘particles-wall’ shear stress, pressure drop and friction factor for coarse-dispersive turbulent slurry flow in a pipe, [10].

The aim of the paper is to present qualitative and quantitative dependence of solid particle diameter, solid particle density, solid concentration, and Reynolds number for carrier liquid phase on the ‘particles-wall’ shear stress. It is demonstrated that the solid particle diameter plays crucial role in its dependence on the ‘particles-wall’ shear stress. It was proved that in particular flow conditions the ‘particles-wall’ shear stress is much higher compared to the carrier liquid wall shear stress.

This paper presents the current study of the distribution of stresses for four-point contact wire race ball bearing. The main aim of this article is to define the most important geometrical rules in a wire-race bearing. The results for bearings of different geometrical parameters are presented. In the study, one also estimates the distribution of internal pressure in particular bearing elements.

Irritable bowel syndrome (IBS) is a chronic functional gastrointestinal disorder diagnosed on the basis of Rome IV criteria. Stress is an important contributor to the development of IBS symptoms, while personality, perceived self-efficacy, resilience, and coping strategies may be indirectly involved in the modulation of the body’s response to various stressors. The aim of this study was to assess the effect of selected personality traits and stress with IBS symptoms. We enrolled 129 participants (59 men and 70 women) aged from 18 to 61 years. The study group included 94 patients with IBS, while the control group comprised 35 participants without a diagnosed psychoso-matic disorder and chronic comorbidities. Participants were assessed using a self-designed questionnaire as well as the Coping Inventory for Stressful Situations, NEO-Five Factor Inventory, 25-item Resilience Coping Scale (Skala Pomiaru Prężności — SPP-25), and General Self-Efficacy Scale. We observed a significant effect of personality, perceived self-efficacy, resilience, and coping strategies in patients with IBS. Moreover, stress was shown to be associated with disease severity, while the type of a coping strategy was related to the frequency of symptoms. The groups differed in terms of personality traits such as resilience, self-efficacy, extraversion, and neuroticism. Our study confirms the significant effect of personality traits and coping strategies in patients with IBS.

Objectives: Medical students are more susceptible to depression than other students. Moreover, students with the symptoms of depression statistically more often abuse drugs and have suicidal thoughts and anxiety. The level of stress and the factors that lead to in among medical students at Polish universities have not yet been measured. The aim of this study was to translate to Polish and validate the Perceived Medical School Stress Instrument (PMSS-PL) and to measure the resulting version’s psychometric abilities.

Materials and Methods: We validated the Polish translation of PMSS in accordance with the recommendations published by the Translation and Cultural Adaptation group of the Quality of Life Special Interest group of the International Society for Pharmacoeconomics and Outcomes Research. The Perceived Stress Scale (PSS-10) was used as an external test to validate the PMSS-PL questionnaire. A total of 430 undergraduate medical students at the Medical College of Jagiellonian University took part.

Results: The mean PMSS-PL score was 36.43 and it varied from 13 to 65. The mean PSS-10 was 21.35. The internal reliability, as indicated by Cronbach’s alpha, was 0.803, which means there was internal reliability between PSS-10 and PMSS-PL. Moreover, all questions from PMSS-PL had a positive discri-mination power, so each question correlated positively with the other questions in PMSS-PL.

Conclusions: PMSS-PL may be used to psychometrically analyze the stress load on undergraduate medical students at Polish universities. The PMSS-PL may also be used as an external test for validating and calculating the reliability and accuracy of other psychometric instruments.