Static friction measurements on steel against uncoated and coated cast iron

Static friction is a phenomenon we may mainly consider as related to frictional joints within staticmechanics. The step from static friction to tribological phenomena is, however, rather short, since at theonset of sliding in a mechanical contact, the static friction determines the initial resistance against motion.Static friction furthermore plays a role in contacts subjected to traction and fretting. Although being aphenomenon of short duration, the tribological phenomena during the transition from static friction to slidingfriction may be of great importance for the operational life of the contact surfaces, particularly if theprocedure is repeated for a sufficient number of times.The present paper describes the principles of static friction measurements, details of the employed staticfriction tribometer and the results of measurements with unlubricated and lubricated sliding couplesconsisting of steel against uncoated and coated cast iron

Segregation, precipitation, and \alpha-\alpha' phase separation in Fe-Cr alloys: a multi-scale modelling approach

Segregation, precipitation, and phase separation in Fe-Cr systems is investigated. Monte Carlo simulations using semiempirical interatomic potential, first-principles total energy calculations, and experimental spectroscopy are used. In order to obtain a general picture of the relation of the atomic interactions and properties of Fe-Cr alloys in bulk, surface, and interface regions several complementary methods has to be used. Using Exact Muffin-Tin Orbitals method the effective chemical potential as a function of Cr content (0-15 at.% Cr) is calculated for a surface, second atomic layer and bulk. At ~10 at.% Cr in the alloy the reversal of the driving force of a Cr atom to occupy either bulk or surface sites is obtained. The Cr containing surfaces are expected when the Cr content exceeds ~10 at.%. The second atomic layer forms about 0.3 eV barrier for the migration of Cr atoms between bulk and surface atomic layer. To get information on Fe-Cr in larger scales we use semiempirical methods. Using combined Monte Carlo molecular dynamics simulations, based on semiempirical potential, the precipitation of Cr into isolated pockets in bulk Fe-Cr and the upper limit of the solubility of Cr into Fe layers in Fe/Cr layer system is studied. The theoretical predictions are tested using spectroscopic measurements. Hard X-ray photoelectron spectroscopy and Auger electron spectroscopy investigations were carried out to explore Cr segregation and precipitation in Fe/Cr double layer and Fe_0.95Cr_0.05 and Fe_0.85Cr_0.15 alloys. Initial oxidation of Fe-Cr was investigated experimentally at 10^-8 Torr pressure of the spectrometers showing intense Cr_2O_3 signal. Cr segregation and the formation of Cr rich precipitates were traced by analysing the experimental spectral intensities with respect to annealing time, Cr content, and kinetic energy of the exited electron.Comment: 16 pages, 14 figures, 52 reference

An uptake and elimination kinetics approach to assess the bioavailability of chromium, copper, and arsenic to earthworms (Eisenia andrei) in contaminated field soils

The aim of this study was to determine the bioavailability of metals in field soils contaminated with chromated copper arsenate (CCA) mixtures. The uptake and elimination kinetics of chromium, copper, and arsenic were assessed in the earthworm Eisenia andrei exposed to soils from a gradient of CCA wood preservative contamination near Hartola, Finland. In soils contaminated with 1480–1590 mg Cr/kg dry soil, 642–791 mg Cu/kg dry soil, and 850–2810 mg Ag/kg dry soil, uptake and elimination kinetics patterns were similar for Cr and Cu. Both metals were rapidly taken up and rapidly excreted by Eisenia andrei with equilibrium reached within 1 day. The metalloid As, however, showed very slow uptake and elimination in the earthworms and body concentrations did not reach equilibrium within 21 days. Bioaccumulation factors (BAF) were low for Cu and Cr (Peer reviewe

Toxicity of binary mixtures of Cu, Cr and As to the earthworm Eisenia andrei

Chromated copper arsenate (CCA) mixtures were used in the past for wood preservation, leading to large scale soil contamination. This study aimed at contributing to the risk assessment of CCA-contaminated soils by assessing the toxicity of binary mixtures of copper, chromium and arsenic to the earthwormEisenia andreiin OECD artificial soil. Mixture effects were related to reference models of Concentration Addition (CA) and Independent Action (IA) using the MIXTOX model, with effects being related to total and available (H2O and 0.01 M CaCl(2)extractable) concentrations in the soil. Since only in mixtures with arsenic dose-related mortality occurred (LC(50)92.5 mg/kg dry soil), it was not possible to analyze the mixture effects on earthworm survival with the MIXTOX model. EC(50)s for effects of Cu, Cr and As on earthworm reproduction, based on total soil concentrations, were 154, 449 and 9.1 mg/kg dry soil, respectively. Effects of mixtures were mainly antagonistic when related to the CA model but additive related to the IA model. This was the case when mixture effects were based on total and H2O-extractable concentrations; when based on CaCl2-extractable concentrations effects mainly were additive related to the CA model except for the Cr-As mixture which acted antagonistically. These results suggest that the CCA components do interact leading to a reduced toxicity when present in a mixture.Peer reviewe

Patients’ involvement in nursing students’ clinical education: A scoping review

BACKGROUND: Actual contacts with patients are crucial in developing the skills that students need when working with patients. Patients are accustomed to the presence of students. The concept of learning from patients has emerged recently, shifting the focus from learning from professionals as role models to the relationship between the student and patient.AIM: With focus on patients' perspective in clinical practice placements, this scoping review aims to review and summarize the existing empirical literature regarding patients' involvement in nursing students' clinical education.DESIGN AND METHOD: A broad search without time limitations was performed in the databases CINAHL, Medline, PsycINFO and ERIC. A manual search was also performed. Only empirical studies describing aspects of patient involvement in nursing education from the patient's perspective were taken into account. Thirty-two studies published from 1985 to June 2016 met the selection criteria and were analysed using inductive content analysis.RESULTS: The perspective of real patients focused on their role in students' learning and assessment processes. In general, patients appreciated the opportunity to contribute to a student's learning process and thus enhance the quality of patient care. However, the patients' approaches varied from active to passive participants, comprising active participants contributing to students' learning, followers of care and advice, and learning platforms with whom students practiced their skills. Some patients perceived themselves as active participants who facilitated students' learning by sharing knowledge and experience about their own care and wellbeing as well as assessed students' performance by providing encouraging feedback.CONCLUSION: The state and degrees of patient involvement in nursing students' clinical education were made explicit by the literature reviewed. However, the number of studies examining the involvement of real patients in students' education in clinical settings is very limited. To understand this untapped resource better and to promote its full realization, recommendations for nursing education and future research are made.</p

Measuring Quality of Care: A Rasch Validity Analysis of the Good Nursing Care Scale

BACKGROUND: Patient-centeredness is emphasized in both health policies and practice, calling for reliable instruments for the evaluation of the quality of nursing care.PURPOSE: The purpose was to analyze the psychometric properties of the Good Nursing Care Scale (GNCS) in a sample of surgical patients and nurses.METHODS: An explorative cross-sectional study design was used. Data were collected with the 40-item GNCS from surgical patients (n = 476) and nurses (n = 167) in Finland. The data were analyzed with Rasch analysis.RESULTS: The GNCS provided evidence of unidimensionality with acceptable goodness-of-fit to the Rasch model in both samples. Person-separation validity was acceptable. Person misfit was reasonable. The Rasch-equivalent Cronbach α was 0.81 (patient data) and 0.88 (nurse data).CONCLUSIONS: The findings support that the GNCS is a psychometrically sound instrument that can be used in measuring the quality of nursing care, from the perspective of both patients and nurses.</div

Validation of the Youth Efficacy/Empowerment Scale – Mental Health Finnish version

Αdolescents face mental health problems and still their mental health needs are often neglected. Empowerment provides adolescents with the skills to impact their own lives and communities in general. The aim of the study is to examine the validity and reliability of the Finnish version of the Youth Efficacy/Empowerment Scale – Mental Health (YES-MH). Data was collected through an online questionnaire from pupils aged 12–17 years in Western Finland, comprised of the following instruments; the YES-MH, the Goodman’s the Strengths and Difficulties Questionnaire (SDQ), and the Warwick-Edinburgh Mental Wellbeing Scale. Exploratory factor analysis was carried out to evaluate construct validity and disclose underlying structures which yielded the following subscales: Self, Services, System. The internal consistency of subscales was analyzed with Cronbach’s α. Construct validity was further investigated by computing the Pearson’s correlations coefficients between the subscales. Furthermore, correlations with SDQ and mental well-being dimensions were explored as measures of convergent validity. In the final model all items the Youth Efficacy/ Empowerment Scale – Mental Health were entered into the factor analysis. All factor loadings were more than 0.40, ranging from 0.63 to 0.89. All the scales exceeded the minimum reliability standard of 0.70 and all corrected item-total correlations were high. All the YES-MH subscales were significantly and positively correlated each other with correlations coefficients ranging from medium to high. Correlations of Mental Well-being score with Self and Services subscales were significant. Moreover, Self subscale was significantly correlated with all SDQ dimensions. Services subscale was significantly correlated with Emotional symptoms and total SDQ score, while System subscale was significantly correlated with Conduct problems. The exploratory factor analysis showed a clear factor structure and the results suggest that the YES-MH is a reliable scale for assessing empowerment among young people. The YES-MH can be useful for health professionals not only as an assessment tool but also when they need to evaluate mental health interventions and examine empowerment as an outcome. However, further research can provide insights for the use of the scale in specific adolescent target groups and among different ethnic groups as well.</p