Amorphization under fracture surface in hydrogen-charged and low- temperature tensile-tested austenitic stainless steel

ABSTRACT

The microstructure just below the fracture surface in hydrogen-charged stable austenitic SUS 316L stainless steel, which was subjected to a low strain rate tensile test at ?70°C, was studied by a combination of the focused-ion-beam method and transmission electron microscopy. An amorphous region with a chemical composition almost identical to that of the polycrystalline region was found under the lath-like structure on the fracture surface, although no deterioration of tensile properties by hydrogen appeared. In the amorphous region, band-like regions with wavy contrasts were observed, which were often accompanied by cracks at the boundaries. The presence of the amorphous region with band-like regions implies that amorphization occurred due to high-density vacancies accompanied by agglomerations of excess vacancies in the hydrogen-charged SUS 316L stainless steel that was tensile-tested at low temperatures.     

骨延长的骨愈合原理

骨延长愈合与骨折愈合等多种多样的骨修复现象可能具有相同的细胞生物学基础,这个理论称为骨修复一元论.血管内皮细胞是启动骨修复的感受器,破骨细胞通过分泌骨形态发生蛋白（BMP）启动骨特异性修复.骨折间隙间断性的力学脉冲通过血管内皮细胞不断地转化为骨修复的生物学脉冲.在微损伤条件下,骨修复具有放大效应.保护下负重和功能锻炼是下肢骨骼延长术后的重要原则.     

Transient Effects of Gaze Stability Exercises on Postural Stability in Patients With Posterior Circulation Stroke

The authors sought to investigate if short-term gaze stability exercises have an effect on postural stability of dynamic standing during neck movement in patients with posterior circulation stroke (PCS). Patients in both PCS and non-PCS groups were assigned to either an intervention or control group. The intervention group performed the gaze stability exercises for 10 min while the control group was merely resting. The center of pressure velocity was calculated to evaluate the postural stability. After intervention, PCS and non-PCS showed a significant reduction in center of pressure velocity during dynamic standing with eyes closed condition, and the PCS group showed a significant improvement in eye-opened condition. This study indicated that gaze stability exercises improve PCS patients' postural control, especially during dynamic standing.     

A survey of smoking status and cancer risk perceptions among participants attending a hospital-based head and neck screening program

Abstract

Screening for head and neck cancer is underutilized. Given that lack of knowledge of the risk factors may partially account for screening underutilization. we surveyed subjective risk and knowledge of risk factors for head and neck cancer among 124 individuals who attended a free. hospital-based head and neck cancer screening. Few participants were current smokers. Most attendees perceived their risk as similar to others of their age and sex. Personal health habits comprised almost all of the risk-decreasing factors, yet less than half of the risk-increasing factors. generated. Personal habits were less frequently endorsed than factors such as pollution and heredity. Those who mentioned a risk behavior, or a family cancer history, reported higher subjective risk. Those who mentioned a personal health habit reported lower subjective risk. Results highlight needed efforts to increase screening among high-risk individuals through targeted education messages.     

Effect of strain rate on the compressive behaviour of a Zr56Al10.9Ni4.6Cu27.8Nb0.7 bulk metallic glass

We report the study of the effect of strain rate on the compressive behaviour of a Zr₅₆Al_10.9Ni_4.6Cu_27.8Nb_0.7 bulk metallic glass. The results indicated that both the strength and plasticity of the glass increase with increasing the strain rate up to 10^?5 s^?1, above which the strength and plasticity start to decrease. The enhanced mechanical properties under a strain rate of 10^?5 s^?1 are due to the emission/propagation rate of the shear bands being consistent with the strain rate.     

Dynamic precipitation at elevated temperatures in a dual-phase AlCoCrFeNi high-entropy alloy: an in situ study

ABSTRACT

The effect of a possible phase transformation or precipitation of the face-centred cubic (FCC) phase on intermediate-temperature deformation of a dual-phase AlCoCrFeNi high-entropy alloy has been studied using in situ tensile testing at 550°C. Electron backscatter diffraction (EBSD) results showed localised precipitation of the FCC phase during the intermediate-temperature deformation. The overall fracture behaviour and crack propagation of the material was not altered much compared to the room-temperature behaviour, namely brittle trans-granular fracture. Deformation at higher temperatures (above 750°C) is suggested as a way to enhance the dynamic FCC phase precipitation, in order to improve the ductility or deformability of the alloy.     

The kinetics of infralow-frequency viscoelastic internal friction induced by irreversible structural relaxation of a metallic glass

This letter presents the results of internal-friction measurements of Co 70 Fe 5 Si 15 B10 metallic glass at temperatures 400K h T h 700K and frequencies 0.01 Hz h f h 0.05Hz. It is shown that Maxwellian viscoelastic damping is predominant in this case. The nature of this damping is determined by irreversible structural relaxation. The kinetic relaxation law is derived.     

A theory of work softening

Observed features of the yield drop in work softening support the view that the structure in a slip band is heterogeneous in a metal such as aluminium or copper. The centre of the band is almost empty of dislocations. These are concentrated round its boundary, particularly as walls of edge dipoles at its ends. It is argued that work hardening is due to the prevention of the passage of these dislocations by a forest of obstacles with small activation volumes and energies. Thermal energy enables them to cut through their obstacles and so to penetrate further into their walls, thereby reducing their back stress and enabling the Frank-Read sources, within the bands, to become active at lower applied stresses. The yield drop is explained as due to an overshooting, resulting from this thermally activated cutting, of the stress to operate the sources.     

Do stigma and its psychosocial impact differ between Asian-born Chinese immigrants and Western-born Caucasians with head and neck cancer?

Stigma appears to influence emotional distress and well-being in cancer survivors, but cross-cultural differences have been ignored. Previous studies suggest that stigma may be especially relevant for survivors of Asian origin. However, their study designs (e.g. focused on female cancers, qualitative designs, and an absence of comparison groups) limit the strength of this conclusion. We hypothesized that (1) Asian-born Chinese immigrants (AI) would report more perceived cancer-related stigma than Western-born Caucasians (WBC); and (2) the impact of stigma on emotional distress and well-being would be greater in AI as compared to WBC. Head and neck cancer survivors (n = 118 AI and n = 404 WBC) completed measures of well-being, emotional distress, and a three-item indicator of stigma in structured interviews. The majority of respondents (59%) reported one or more indicators of stigma. Stigma correlated significantly with emotional distress (r = .13, p = .004) and well-being (r = ?.09, p = .032). Contrary to our hypotheses, WBCs and AIs did not differ in reported stigma nor did we detect differences in its psychosocial impact. Stigma exerts a deleterious psychosocial impact on head and neck cancer survivors. It did not differ significantly between AI and WBC survivors.     

Changes over time in head and neck cancer patients’ and caregivers’ illness perceptions and relationships with quality of life

Objective: This study investigated changes in illness perceptions from diagnosis to six months later in patients with head and neck cancer (HNC) and their caregivers. The study also examined whether discrepancy in patient and caregiver perceptions at diagnosis predicted patient health-related quality of life (HRQL) at six months.

Design: Forty-two patient–caregiver dyads completed the Brief Illness Perception Questionnaire (Brief IPQ) at diagnosis and again six months later. Patients also completed a HRQL questionnaire at both time points. Analyses were performed using the Actor–Partner Interdependence Model.

Main Outcome Measure: Total patient HRQL assessed by the Functional Assessment of Cancer Therapy (FACT-H&N).

Results: Perceptions of emotional impact and illness concern reduced over time in patients and caregivers. Perceptions of treatment control and identity increased in caregivers only. After controlling for the effects of baseline HRQL, and the individual contribution of patient and caregiver illness perceptions, greater discrepancy in perceptions of timeline, personal control, and illness identity among dyads at diagnosis predicted lower patient HRQL at six-month follow-up.

Conclusion: Patients’ and their caregivers’ perceptions of HNC are dynamic over time. Greater discrepancy between patients’ and caregivers’ illness perceptions at diagnosis predict poorer subsequent patient HRQL.