Deformation, acoustic emission and ultrasound velocity during fatigue tests on paper

We study the evolution of mechanical properties of paper samples during cyclic experiments. The issue is to look at the sample-to-sample variation, and we try to predict the number of loading cycles to failure. We used two concurrent methods to obtain the deformation: the strain was calculated from vertical displacement measured by laser interferometer sensor, as well as, computed by digital image correlation technique from pictures taken each 2s by a camera. Acoustic emission of fracture was also recorded, and an active ultrasonic wave method using piezoelectric transducers is used to follow the viscoelastic behaviour of each sample. We found that a sharp final increase of different variables like deformation, strain rate and fluctuations, are signs of an imminent rupture of the paper. Moreover looking at the evolution of these quantities during the first cycle only is already an indicator about the lifetime of the sample.Peer reviewe

Valence-state mixing and separation in SmBaFe2O5+w

A mixed-valence state, formally denoted as Fe2.5+, is observed in the 300 K Mössbauer spectra of the most reduced samples of SmBaFe2O5+w. Upon cooling below the Verwey-type transition temperature (TV≈200K), the component assigned to Fe2.5+ separates into a high-spin Fe3+ state and an Fe2+ state with an unusually low internal field. The separation of the mixed-valence state at TV is also confirmed by magnetic susceptibility measurements and differential scanning calorimetry. A model is proposed which accounts for the variation of the amount of the mixed-valence state with the oxygen content parameter w.Peer reviewe

Cross-Cultural Adaptation and Validation of the Finnish Version of the Michigan Hand Outcomes Questionnaire

Background and Aims: Michigan Hand Outcomes Questionnaire is a widely used patient-reported outcome measure in hand surgery. The aim of this study was to translate and validate the Michigan Hand Outcomes Questionnaire into Finnish for Finnish patients with hand problems following international standards and guidelines. Material and Methods: The original English Michigan Hand Outcomes Questionnaire was translated into Finnish. Altogether, 115 patients completed the Finnish Michigan Hand Outcomes Questionnaire, and reference outcomes: Disabilities of the Arm and Shoulder, EQ-5D 3L and pain intensity on a visual analog scale. Grip and key pinch forces were measured. After 1-2 weeks, 63 patients completed the Finnish Michigan Hand Outcomes Questionnaire the second time. The Michigan Hand Outcomes Questionnaire was analyzed for internal consistency, repeatability, correlations with the reference outcomes, and factor analysis. Results: Cronbach's alpha ranged from 0.90 to 0.97 in all the Michigan Hand Outcomes Questionnaire subscales, showing high internal consistency. The intraclass correlation coefficient showed good to excellent test-retest reliability ranging from 0.66 to 0.91 in all the Michigan Hand Outcomes Questionnaire subscales. In factor analysis, the structure with six subscales was not confirmed. All the subscales correlated with Disabilities of the Arm and Shoulder score, and five subscales correlated with EQ-5D index. Conclusion: The Finnish version of the Michigan Hand Outcomes Questionnaire showed similar properties compared to the original English version and thus can be used as patient-reported outcome measure for Finnish patients with hand problems.Peer reviewe

Valence-state mixing and separation in SmBaFe2O5+w

A mixed-valence state, formally denoted as Fe2.5+, is observed in the 300 K Mössbauer spectra of the most reduced samples of SmBaFe2O5+w. Upon cooling below the Verwey-type transition temperature (TV≈200K), the component assigned to Fe2.5+ separates into a high-spin Fe3+ state and an Fe2+ state with an unusually low internal field. The separation of the mixed-valence state at TV is also confirmed by magnetic susceptibility measurements and differential scanning calorimetry. A model is proposed which accounts for the variation of the amount of the mixed-valence state with the oxygen content parameter w.Peer reviewe

O K -edge and CuL23-edge XANES study on the concentration and distribution of holes in the (Pb2/3Cu1/3)3Sr2(Y ,Ca)Cu2O8+z superconductive phase

By means of high-resolution O K-edge and Cu L23-edge x-ray absorption near-edge-structure spectroscopy continuous increase of the CuO2-plane hole concentration with increasing Ca-substitution level has been established for the superconductive, oxygen-depleted (z≈0) (Pb2/3Cu1/3)3Sr2(Y1−xCax)Cu2O8+z [(Pb2/3Cu1/3)−3212] phase with a three-layer PbO-Cu-PbO charge-reservoir block. For the O K-edge absorption, a pre-edge peak at ∼528.3 eV is seen, originating from the excitation of the O 1s electron to the O 2p hole state located in the CuO2 plane. With increasing Ca-substitution level, the intensity of this peak continuously increases within the substitution range studied, i.e., 0<~x<~0.5. Consistently, with increasing x, the shoulder on the high-energy side of the main absorption peak at ∼932.0 eV in the Cu L23-edge spectra, i.e., a feature typically assigned to formally trivalent copper, enhances. From the Cu L23-edge spectra it was furthermore confirmed that the charge-reservoir copper remains in the monovalent state, indicating that the holes created through Ca substitution are directed solely into the superconductive CuO2 plane. In terms of increasing the CuO2-plane hole concentration, Ca substitution was found to work more efficiently in (Pb2/3Cu1/3)−3212 as compared to, e.g., the related Bi-2212 phase.Peer reviewe

Phase formation and magnetotransport of alkali metal doped Na[sub 0.75]CoO[sub 2] thermoelectric oxide

Synthesis and characterization of bulk NaxCoO2 samples substituted by K and Rb is reported. Phase formation studies revealed a narrow stable region for Na-alkali metal-Co system. Whisker and platelike single crystalline structures have been found to form on the surface of the pellets in case of K doping. All samples were metallic and no characteristic anomaly in R-T curves was observed for Rb doped sample. Magnetoresistance measured has a pronounced positive response only for K-doped and pure NaxCoO2 phases, reaching 11% and 7% at 5 K temperature, respectively.Peer reviewe

Degenerative cervical spine changes among early career fighter pilots : a 5-year follow-up

Introduction Degenerative changes of the cervical spine often cause disability and flight duty limitations among Finnish Air Force (FINAF) fighter pilots. We aimed to study the effect of +Gz exposure on degenerative changes in the cervical spine by comparing cervical MRIs of FINAF fighter pilots and controls. Methods At baseline, the volunteer study population consisted of 56 20-year-old FINAF male fighter pilots (exposure group) and 56 21-year-old Army and Navy cadets (control group). Both groups underwent MRI of the cervical spine at the baseline and after 5 years. Degenerative changes evaluated using MRI included intervertebral disc (IVD) degeneration (Pfirrmann classification), disc herniations, uncovertebral arthrosis, Schmorl’s nodes, Modic changes, spinal canal stenosis, kyphosis and scoliosis. Results The degree of IVD degeneration in the whole cervical spine increased significantly in both populations with no between-group differences. The prevalence of disc herniations also tended to increase in both populations with no difference in the incidence over the follow-up. However, pilots proved to have more disc herniations at the baseline and at the follow-up. There were virtually no between-group differences in other assessed degenerative changes. Discussion We found that IVD degeneration and the prevalence of disc herniations increased at a similar rate for fighter pilots and non-flying military students when all cervical levels were summed up. The lack of difference may be explained by the relatively low cumulative +Gz exposure during the first 5 years of a pilots’ career

Opto-PCB: Three demonstrators for optical interconnections

We report on a research project targeting optical waveguide integrated PCBs conducted within the European FP6 Network of Excellence on Micro-Optics NEMO. For three identified feature requests we have built three specific demonstrators respectively addressing the integration of active components, the fabrication of peripheral fibre ribbons and the integration of multiple layers of waveguides on the board