Effects of Irradiation and Thermal Annealing on the Mechanical and Microstructural Properties of Bulk Metallic Glasses

A series of ion irradiation and annealing experiments have been performed on Zr52.5Cu17.9Ni14.6Al10Ti5 “BAM-11” and Cu60Zr20Hf10Ti10 bulk metallic glass (BMG) specimens to evaluate their irradiation- and temperature-induced microstructural and mechanical property evolution. These experiments covered four main themes, namely, ion irradiation, neutron irradiation, thermal annealing, and helium implantation. For the ion irradiations, samples were exposed to 9 MeV Ni and 5.5 MeV C ions at temperatures ranging from room temperature to 360 oC. For the Ni ion irradiations the samples were exposed to midrange (~1.5 m depth) doses of 0.5 and 10 displacements per atom (dpa), while the C ion irradiations samples were irradiated to a midrange dose of 0.5 dpa. For the neutron irradiations, samples were irradiated by neutrons (E \u3e 0.1 MeV) at ~70 oC to fluences of 1.4 × 1020 n/cm2 and 1.4 × 1021 n/cm2 (doses of 0.1 and 1 dpa). Thermal annealing experiments involved heating the samples to various temperatures ranging from 25 - 770 oC. For the helium implantation experiments, amorphous and partially crystallized BMGs were exposed to helium fluences of 2 × 1015 and 5 × 1015 cm-2 . The mechanical property and microstructural characterization included nanoindentation, compression testing, bend testing, Xray diffraction (XRD), neutron diffraction, thermal desorption analysis (TDS), and nuclear reaction analysis. From the experiments, several important conclusions were obtained. The results of the XRD and nanoindentation characterizations of the ion irradiated and thermal annealed specimens indicate good stability during irradiation at 25 to 290 oC up to at least 10 dpa but suggest that the BAM-11 BMG is not suitable for irradiation environments where temperatures exceed 300 oC for prolonged periods of time. As for the neutron irradiation and thermal annealing experiments, significant softening was observed in the sample irradiated by neutrons, while postirradiation annealing led to a marked increase in hardening. Neutron diffraction results indicated vi that primary knock-on events caused rejuvenation (disordering) while annealing resulted in structural relaxation. The results of the TDS experiments found that for the lower He implantation fluence, He desorbed more quickly in the partially crystallized alloy, indicating a structural effect on the mobility of He

Scaling and complexity of stress fluctuations associated with smooth and jerky flow in a FeCoNiTiAl high-entropy alloy

Recent observations of jerky flow in high-entropy alloys (HEA) revealed a high role of self-organization of dislocations in their plasticity. The present work reports first results of investigation of stress fluctuations during plastic deformation of a FeCoNiTiAl alloy, examined in a wide temperature range covering both smooth and jerky flow. These fluctuations, which accompany the overall deformation behavior representing an essentially slower stress evolution controlled by the work hardening, were processed using complementary approaches comprising the Fourier spectral analysis, the refined composite multiscale entropy, and multifractal formalisms. The joint analysis at distinct scales testified that even a macroscopically smooth plastic flow is accompanied with nonrandom fluctuations, disclosing self-organized dynamics of dislocations. Qualitative changes in such a fine-scale "noise" were found with varying temperature. The observed diversity is significant for understanding the relationships between different scales of plasticity of HEAs and crystal materials in general.Comment: 13 pages main body, 6 figures, 2 appendices, 65 citations (22 pages overall

Quality of life and the impact of drug toxicities in a South African community-based antiretroviral programme

<p>Abstract</p> <p>Background</p> <p>The impact of highly active antiretroviral therapy (HAART) on health-related quality of life has been widely researched in the developed world, but there are few data from sub-Saharan Africa, where the vast majority of HIV-infected individuals live. This study examined health-related quality of life among HIV-positive individuals initiating HAART in Cape Town, South Africa, and explored the impact of HAART-related drug toxicities on quality of life.</p> <p>Methods</p> <p>Health-related quality of life was assessed using a standardised questionnaire, the Medical Outcomes Survey Short Form 36. Physical health summary scores and mental health summary scores were compared pre-HAART and at regular intervals during the first 48 weeks of HAART. The relationships between socio-demographic, baseline and on-treatment variables and decline in health-related quality of life, as well as the impact of drug toxicities on quality of life, were assessed in unadjusted bivariate and adjusted multivariate analyses.</p> <p>Results</p> <p>Two hundred and ninety-five patients were enrolled into the study. There was a significant increase in health-related quality of life during the first 48 weeks on HAART. The median physical health summary score increased from 45 to 53 units (p < 0.001) and median mental health summary score increased from 45 to 50 units (p < 0.001).</p> <p>The bulk of this increase occurred during the first 16 weeks. Overall, 23% of participants experienced a decline in their physical health summary score, while 34% showed a decline in the mental health summary score. Average drops in median physical and mental health summary scores were 8.4 units (SD 9.31) and 9.9 (SD 11.4) units respectively. Participants with drug toxicity had lower physical health summary scores than participants without drug toxicity at all time points. However, only three participants with toxicity (27%) reported an actual decline in health-related quality of life by week 48. Drug toxicities had little impact on mental health summary scores.</p> <p>Conclusion</p> <p>These results confirm the health-related quality of life benefits of HAART. While the majority of patients experienced a significant improvement in health-related quality of life on HAART, up to a third of patients reported declines in this quality of life. This was largely related to better baseline clinical state. HAART-related drug toxicities did not have a significant impact on health-related quality of life during the first year of HAART, which supports the ongoing use of the current national first-line regimen.</p

Prevalence of distressing symptoms in hospitalised patients on medical wards: A cross-sectional study

<p>Abstract</p> <p>Background</p> <p>Many patients with advanced, serious, non-malignant disease belong to the population generally seen on medical wards. However, little research has been carried out on palliative care needs in this group. The aims of this study were to estimate the prevalence of distressing symptoms in patients hospitalised in a Department of Internal Medicine, estimate how many of these patients might be regarded as palliative, and describe their main symptoms.</p> <p>Methods</p> <p>Cross-sectional (point prevalence) study. All patients hospitalised in the Departments of Internal Medicine, Pulmonary Medicine, and Cardiology were asked to do a symptom assessment by use of the Edmonton Symptom Assessment System (ESAS). Patients were defined as "palliative" if they had an advanced, serious, chronic disease with limited life expectancy and symptom relief as the main goal of treatment.</p> <p>Results</p> <p>222 patients were registered in all. ESAS was completed for 160 patients. 79 (35.6%) were defined as palliative and 43 of them completed ESAS. The patients in the palliative group were older than the rest, and reported more dyspnea (70%) and a greater lack of wellbeing (70%). Other symptoms reported by this group were dry mouth (58%), fatigue (56%), depression (41%), anxiety (37%), pain at rest (30%), and pain on movement (42%).</p> <p>Conclusion</p> <p>More than one third of the patients in a Department of Internal Medicine were defined as palliative, and the majority of the patients in this palliative group reported severe symptoms. There is a need for skills in symptom control on medical wards.</p

The symptom experience of people living with HIV and AIDS in the Eastern Cape, South Africa

<p>Abstract</p> <p>Background</p> <p>Symptom management for persons living with HIV (PLHIV) or AIDS is an important part of care management. Limited information about symptom prevalence exists about HIV infected persons in South Africa, in particular in the context of antiretroviral treatment (ART). The aim of this study was to assess HIV symptoms and demographic, social and disease variables of people living with HIV in South Africa.</p> <p>Methods</p> <p>In 2007 607 PLHIV, sampled by all districts in the Eastern Cape Province and recruited through convenience sampling, were interviewed by PLHIV at health facilities, key informants in the community and support groups.</p> <p>Results</p> <p>Two-thirds of the PLHIV (66%) classified themselves with being given an AIDS (advanced stage of HIV) diagnosis, 48% were currently on ART, 35% were currently on a disability grant for HIV/AIDS and for 13% the disability grant had been stopped. Participants reported that on the day of the interview, they were experiencing an average of 26.1 symptoms out of a possible 64. In a regression model with demographic and social variables, higher HIV symptom levels were associated with lower educational levels, higher age, urban residence and not on a disability grant, lack of enough food and having a health insurance, and in a regression model with demographic, social and disease variables only being on ART, lack of enough food and having a health insurance were associated with HIV symptoms.</p> <p>Conclusion</p> <p>Symptom assessment provides information that may be valuable in evaluating AIDS treatment regimens and defining strategies to improve quality of life. Because of the high levels of symptoms reported, the results imply an urgent need for effective health care, home- and community-based as well as self-care symptom management to help patients and their families manage and control AIDS symptoms.</p

An Educational Intervention to Reduce Pain and Improve Pain Management for Malawian People Living With HIV/AIDS and Their Family Carers: A Randomized Controlled Trial

CONTEXT: Advances being made in improving access to HIV drugs in resource-poor countries mean HIV patients are living longer, and, therefore, experiencing pain over a longer period of time. There is a need to provide effective interventions for alleviating and managing pain. OBJECTIVES: To assess whether a pain educational intervention compared with usual care reduces pain severity and improves pain management in patients with HIV/AIDS and their family carers. METHODS: This was a randomized, parallel group, superiority trial conducted at HIV and palliative care clinics of two public hospitals in Malawi. A total of 182 adults with HIV/AIDS (Stage III or IV) and their family carers participated; carer participants were those individuals most involved in the patient's unpaid care. The educational intervention comprised a 30 minute face-to-face meeting, a leaflet, and a follow-up telephone call at two weeks. The content of the educational intervention covered definition, causes, and characteristics of pain in HIV/AIDS; beliefs and myths about pain and pain medication; assessment of pain; and pharmacological and nonpharmacological management. The primary outcome was average pain severity measured by the Brief Pain Inventory-Pain Severity subscale. Assessments were recorded at baseline before randomization and at eight weeks after randomization. RESULTS: Of the 182 patient/carer dyads randomly allocated, 157 patient/carer dyads completed the trial. Patients in the intervention group experienced a greater decrease in pain severity (mean difference = 21.09 points, 95% confidence interval = 16.56-25.63; P < 0.001). CONCLUSION: A short pain education intervention is effective in reducing pain and improving pain management for Malawian people living with HIV/AIDS and their family carers