Strain Hardening and Recovery in High-Temperature Deformation by Pure-Metal Mode

By a new method using the stress relaxation test, the coefficient of strain hardening without recovery (h) and the rate of recovery without strain hardening (r) are estimated in high-temperature deformation of fcc aluminum and b c c iron, where the internal stress is confirmed to be nearly 100% of the flow stress. Both h and r are dependent on applied stress σ and temperature T in a steady-state deformation, and are represented by h=h_0(σ/E)^m exp(-Q_h/RT) and r=r_0 (σ/E)^l exp (-Q_r/RT), where h_0 and r_0 are constants, E is Young\u27s modulus and m=-0.88(-1.5), l=4.3(3.2), Q_h=-22(-76) kJ/mol, Q_r=88(132) kJ/mol for aluminum(iron). During a transient state of tensile deformation in the constant strain-rate test, h and r are nearly independent of strain. The activation energy for recovery (Q_r) is found to be appreciably smaller than that of self-diffusion, and then possible roles of pipe-diffusion and strain-enhanced diffusion in dynamic recovery are discussed

Influence of Years of Experience on Clinical Competence of Novice Physical and Occupational Therapists in Japan

Purpose: To increase the clinical competence of novice physical and occupational therapists, an accurate assessment of their clinical competence is necessary. However, no previous study has objectively analyzed the changes in novice therapists’ clinical competence in Japan. Hence, this study investigated and evaluated the changes in the clinical competence of such therapists using an objective analysis. Method: The study included 34 novice therapists with 1–3 years of experience in clinical practice. Participants were divided into groups according to their years of experience. The clinical competence of the novice therapists was evaluated twice using a clinical competency evaluation scale. For comparison among the 3 groups, the scores of the first evaluation were used. For comparison within each experience-year, the scores from both evaluations were used. Results: A comparison of the 3 groups showed that therapists with 3 years of clinical experience had significantly higher clinical competence than therapists with 1 year of clinical experience. Between the first and second evaluations, all therapists with 1 year of clinical experience demonstrated increased scores, whereas scores decreased by approximately 50% for therapists with 2–3 years of clinical experience. Conclusion: These findings suggest that it is necessary to increase educational opportunities for therapists with 2−3 years of clinical experience and re-examine the content of their education and training

Evaluation of the relationship between joint torque and angular velocity using a modified leg extension machine

OBJECTIVE: When performing knee extension using a leg extension machine, the lower limb is pushed back in the direction in which knee flexion occurs in response to the freefall of the weight after maximal knee extension. Therefore, eccentric contractions of the knee extensors are needed, which may lead to cumulative fatigue of the extensors, consequently reducing the reliability of the knee extensor torque values. This study aimed to determine the relationship between joint torque and angular velocity in one repetition maximum (1RM) measurement for knee extension using a leg extension machine with and without a modification to prevent counter-rotation. METHODS: Twenty-one healthy adult men (mean age: 27.7±5.4 years) participated in the study. A leg extension machine was modified to prevent counter-rotation due to the freefall of weights. The subjects performed knee extension using the modified leg extension machine, and the joint torque and angular velocity were calculated using two-dimensional analysis. A regression equation between these two factors was created to estimate the maximal isometric torque. RESULTS: Both the joint torque and angular velocity tended to increase after modification of the leg extension machine, although these differences were not significant. Similarly, there were no significant post-modification changes in the estimated maximal isometric torque. CONCLUSIONS: Our results showed that the joint torque, angular velocity, and estimated maximal isometric torque remained unchanged after machine modification; thus, the modified leg extension machine may make it possible to produce the knee extensor torque more safely in 1RM measurement

A Cadmium-Free Cu2ZnSnS4/ZnO Hetrojunction Solar Cell Prepared by Practicable Processes

A cadmium-free Cu2ZnSnS4/ZnO hetrojunction solar cell with conversion efficiency of 4.29% has been obtained. The Cu2ZnSnS4 absorber film was formed utilizing sulfurization of laminated metallic precursors, and the ZnO buffer layer was then deposited on it by ultrasonic spray pyrolysis. In comparison with a conventional Cu2ZnSnS4/CdS hetrojunction solar cell, the open circuit voltage as well as the relative quantum efficiency at the short-wavelength regions was increased. The in-plane homogeneity of p-n junction was improved by depositing the ZnO layer on Cu2ZnSnS4 film via ultrasonic spray pyrolysis. (C) 2011 The Japan Society of Applied PhysicsArticleJAPANESE JOURNAL OF APPLIED PHYSICS. 50(3): 032301 (2011)journal articl