Processing maps for hot working of Cu-Ni-Zn alloys Part II Alpha-Beta nickel silver

The constitutive behaviour of agr-beta nickel silver in the temperature range 600�850 °C and strainrate range 0.001�100s�1 was characterized with the help of a processing map generated on the principles of the dynamic materials model. On the basis of the flow-stress data, processing maps showing the variation of the efficiency of power dissipation (given by [2m/(m+1)], wherem is the strain-rate sensitivity) with temperature and strain rate were obtained, agr-beta nickel silver exhibits a single domain at temperatures greater than 700 °C and at strain rates lower than 1 s�1 with a maximum efficiency of power dissipation of about 42% occurring at about 850 °C and at 0.1 s�1. In the domain, the agr phase undergoes dynamic recrystallization and controls the deformation of the alloy, while the beta phase deforms superplastically. Optimum conditions for the processing of agr-beta nickel silver are 850 °C and 0.1 s�1. The material undergoes unstable flow at strain rates of 10 and 100 s�1 and in the temperature range 600�750 °C, manifestated in the form of adiabatic shear bands.

Improved utilisation of an HF transformer in DC–AC application

Power conversion using high frequency (HF) link converters is popular because of compact size and light weight of highfrequency transformer. This study focuses on improved utilisation of HF transformer in DC–AC applications. In practical application, the operating condition of the power converter deviates significantly from the designed considerations. These deviating factors are commutation requirements (dead-time, overlap), mismatch in device drops and presence of the fundamental frequency in load current. As a result, the HF transformer handles some amount of low-frequency components (including DC) other than desired HF components. This causes the operating point in B-H curve to shift away from its normal or idealised position and hence results poor utilisation of the HF transformer and unwanted losses. This study investigates the nature of the problem with experimental determination of approximate lumped parameter modelling and saturation behaviour (B-H curve) of the HF transformer. A simple closed-loop control algorithm with online tuning of the controller parameters is proposed to improve the utilisation of the isolation transformer. The simulation and experimental results are presented.

A Modified Free Volume Model For Characterizing Of Rate Effect In Bulk Metallic Glasses

We investigate the plastic deformation and constitutive behaviour of bulk metallic glasses (BMGs). A dimensionless Deborah number De(ID) = t(r)/t(i) is proposed to characterize the rate effect in BMGs, where t(r) is the structural relaxing characteristic time of BMGs under shear load, t(i) is the macroscopic imposed characteristic time of applied stress or the characteristic time of macroscopic deformation. The results demonstrate that the modified free volume model can characterize the strain rate effect in BMGs effectively.

Mechanical characterisation of hydrogel materials

Interest in hydrogel materials is growing rapidly, due to the potential for hydrogel use in tissue engineering and drug delivery applications, and as coatings on medical devices. However, a key limitation with the use of hydrogel materials in many applications is their relatively poor mechanical properties compared with those of (less biocompatible) solid polymers. In this review, basic chemistry, microstructure and processing routes for common natural and synthetic hydrogel materials are explored first. Underlying structure-properties relationships for hydrogels are considered. A series of mechanical testing modalities suitable for hydrogel characterisation are next considered, including emerging test modalities, such as nanoindentation and atomic force microscopy (AFM) indentation. As the data analysis depends in part on the material's constitutive behaviour, a series of increasingly complex constitutive models will be examined, including elastic, viscoelastic and theories that explicitly treat the multiphasic poroelastic nature of hydrogel materials. Results from the existing literature on agar and polyacrylamide mechanical properties are compiled and compared, highlighting the challenges and uncertainties inherent in the process of gel mechanical characterisation. © 2014 Institute of Materials, Minerals and Mining and ASM International.

Deformation of titanium alloy Ti-6Al-4V under dynamic compression

Deformation localisation is the main reason for material failure in cold forging of titanium alloys and is thus closely related to the production yield of cold forging. In the study of the influence of process parameters on dynamic compression, considering material constitutive behaviour, physical parameters and process parameters, a numerical dynamic compression model for titanium alloys has been constructed. By adjusting the process parameters, the severity of strain localisation and stress state in the localised zone can be controlled thus enhancing the compression performance of titanium alloys.

A material model for multiaxial stretching and stress relaxation of polypropylene under process conditions

Polypropylene sheets have been stretched at 160 °C to a state of large biaxial strain of extension ratio 3, and the stresses then allowed to relax at constant strain. The state of strain is reached via a path consisting of two sequential planar extensions, the second perpendicular to the first, under plane stress conditions with zero stress acting normal to the sheet. This strain path is highly relevant to solid phase deformation processes such as stretch blow moulding and thermoforming, and also reveals fundamental aspects of the flow rule required in the constitutive behaviour of the material. The rate of decay of stress is rapid, and such as to be highly significant in the modelling of processes that include stages of constant strain. A constitutive equation is developed that includes Eyring processes to model both the stress relaxation and strain rate dependence of the stress. The axial and transverse stresses observed during loading show that the use of a conventional Levy-Mises flow rule is ineffective, and instead a flow rule is used that takes account of the anisotropic state of the material via a power law function of the principal extension ratios. Finally the constitutive model is demonstrated to give quantitatively useful representation of the stresses both in loading and in stress relaxation.

DEAD-box helicase DP103 defines metastatic potential of human breast cancers

Despite advancement in breast cancer treatment, 30% of patients with early breast cancers experience relapse with distant metastasis. It is a challenge to identify patients at risk for relapse; therefore, the identification of markers and therapeutic targets for metastatic breast cancers is imperative. Here, we identified DP103 as a biomarker and metastasis-driving oncogene in human breast cancers and determined that DP103 elevates matrix metallopeptidase 9 (MMP9) levels, which are associated with metastasis and invasion through activation of NF-κB. In turn, NF-κB signaling positively activated DP103 expression. Furthermore, DP103 enhanced TGF-β-activated kinase-1 (TAK1) phosphorylation of NF-κB-activating IκB kinase 2 (IKK2), leading to increased NF-κB activity. Reduction of DP103 expression in invasive breast cancer cells reduced phosphorylation of IKK2, abrogated NF-κB-mediated MMP9 expression, and impeded metastasis in a murine xenograft model. In breast cancer patient tissues, elevated levels of DP103 correlated with enhanced MMP9, reduced overall survival, and reduced survival after relapse. Together, these data indicate that a positive DP103/NF-κB feedback loop promotes constitutive NF-κB activation in invasive breast cancers and activation of this pathway is linked to cancer progression and the acquisition of chemotherapy resistance. Furthermore, our results suggest that DP103 has potential as a therapeutic target for breast cancer treatment.

A comparative evaluation of functions for the analysis of growth in male broilers

Data from six studies with male broilers fed diets covering a wide range of energy and protein were used in the current two analyses. In the first analysis, five models, specifically re-parameterized for analysing energy balance data, were evaluated for their ability to determine metabolizable energy intake at maintenance and efficiency of utilization of metabolizable energy intake for producing gain. In addition to the straight line, two types of functional form were used. They were forms describing (i) diminishing returns behaviour (monomolecular and rectangular hyperbola) and (ii) sigmoidal behaviour with a fixed point of inflection (Gompertz and logistic). These models determined metabolizable energy requirement for maintenance to be in the range 437-573 kJ/kg of body weight/day depending on the model. The values determined for average net energy requirement for body weight gain varied from 7(.)9 to 11(.)2 kJ/g of body weight. These values show good agreement with previous studies. In the second analysis, three types of function were assessed as candidates for describing the relationship between body weight and cumulative metabolizable energy intake. The functions used were: (a) monomolecular (diminishing returns behaviour), (b) Gompertz (smooth sigmoidal behaviour with a fixed point of inflection) and (c) Lopez, France and Richards (diminishing returns and sigmoidal behaviour with a variable point of inflection). The results of this analysis demonstrated that equations capable of mimicking the law of diminishing returns describe accurately the relationship between body weight and cumulative metabolizable energy intake in broilers.

Family physical activity and sedentary environments and weight change in children

<b>Objectiveb><b>. b>To examine associations between family physical activity and sedentary environment and changes in body mass index (BMI) z-scores among 10-12-year-old children over three years. <br /><b>Method. Design. b>Longitudinal (three-year follow-up). Subjects. In total, 152 boys and 192 girls aged 10-12 years at baseline. <br /><b>Measurementsb>. Measured height and weight at baseline and follow-up (weight status, BMI z-scores); aspects of the family physical activity and sedentary environment (parental and sibling modelling, reinforcement, social support, family-related barriers, rules/restrictions, home physical environment) measured with a questionnaire completed by parents at baseline. <br /><b>Resultsb>. At baseline, 29.6% of boys and 21.9% of girls were overweight or obese, and mean (standard deviation, SD) BMI z-scores were 0.44 (0.99) and 0.28 (0.89), respectively. There was a significant change in BMI z-score among girls (mean change=0.19, SD=0.55, p<0.001), but not boys. Among boys, the number of items at home able to be used for sedentary behaviour (B=0.11, p=0.037) was associated with relatively greater increases in BMI z-score. Among girls, sibling engagement in physical activity at least three times/wk (B=-0.17, p=0.010) and the number of physical activity equipment items at home (B=-0.05, p=0.018) were associated with relatively greater decreases in BMI z-score. <br /><b>Conclusion.b> Sibling physical activity and environmental stimuli for sedentary behaviours and physical activity within the home may be important targets for prevention of weight gain during the transition from childhood to adolescence. <br />

Effectiveness of a community-based osteoporosis education and self-management course : a wait list controlled trial

<b>Summary : b>Osteoporosis is an increasing burden on individuals and health resources. The Osteoporosis Prevention and Self-Management Course (OPSMC) was designed to assist individuals to prevent and manage osteoporosis; however, it had not been evaluated in an Australian setting. This randomised controlled trial showed that the course increased osteoporosis knowledge.<br /><b>Introduction and hypothesis :b> Osteoporosis is a major and growing public health concern. An OPSMC was designed to provide individuals with information and skills to prevent or manage osteoporosis, but its effectiveness has not previously been evaluated. This study aimed to determine whether OPSMC attendance improved osteoporosis knowledge, self-efficacy, self-management skills or behaviour.<b><br />Materials and methods : b>Using a wait list randomised controlled trial design, 198 people (92% female) recruited from the community and aged over 40 (mean age = 63) were randomised into control (n = 95) and intervention (n = 103) groups. The OPSMC consists of four weekly sessions which run for 2 h and are led by two facilitators. The primary outcome were osteoporosis knowledge, health-directed behaviour, self-monitoring and insight and self-efficacy.<br /><b>Results :b> The groups were comparable at baseline. At 6-week follow-up, the intervention group showed a significant increase in osteoporosis knowledge compared with the control group; mean change 3.5 (p < 0.001) on a measure of 0–20. The intervention group also demonstrated a larger increase in health-directed behaviour, mean change 0.16 (p < 0.05), on a measure of 0–6.<b><br />Conclusion :b> The results indicate that the OPSMC is an effective intervention for improving understanding of osteoporosis and some aspects of behaviour in the short term.<br />

A heuristic model selection scheme for representing hot flow data using the hot torsion test results

The problem of "model selection" for expressing a wide range of constitutive behaviour adequately using hot torsion test data was considered here using a heuristic approach. A model library including several nested parametric linear and non-linear models was considered and applied to a set of hot torsion test data for API-X 70 micro-alloyed steel with a range of strain rates and temperatures. A cost function comprising the modelled hot strength data and that of the measured data were utilized in a heuristic model selection scheme to identify the optimum models. It was shown that a non-linear rational model including ten parameters is an optimum model that can accurately express the multiple regimes of hardening and softening for the entire range of the experiment. The parameters for the optimum model were estimated and used for determining variations of hot strength of the samples with deformation.

Home and neighbourhood correlates of BMI among children living in socioeconomically disadvantaged neighbourhoods

A detailed understanding of the underlying drivers of obesity-risk behaviours is needed to inform prevention initiatives, particularly for individuals of low socioeconomic position who are at increased risk of unhealthy weight gain. However, few studies have concurrently considered factors in the home and local neighbourhood environments, and little research has examined determinants among children from low socioeconomic backgrounds. The present study examined home, social and neighbourhood correlates of BMI (kg/m2) in children living in disadvantaged neighbourhoods. Cross-sectional data were collected from 491 women with children aged 5–12 years living in forty urban and forty rural socioeconomically disadvantaged areas (suburbs) of Victoria, Australia in 2007 and 2008. Mothers completed questionnaires about the home environment (maternal efficacy, perceived importance/beliefs, rewards, rules and access to equipment), social norms and perceived neighbourhood environment in relation to physical activity, healthy eating and sedentary behaviour. Children's height and weight were measured at school or home. Linear regression analyses controlled for child sex and age. In multivariable analyses, children whose mothers had higher efficacy for them doing physical activity tended to have lower BMI z scores (B = − 0·04, 95 % CI − 0·06, − 0·02), and children who had a television (TV) in their bedroom (B = 0·24, 95 % CI 0·04, 0·44) and whose mothers made greater use of food as a reward for good behaviour (B = 0·05, 95 % CI 0·01, 0·09) tended to have higher BMI z scores. Increasing efficacy among mothers to promote physical activity, limiting use of food as a reward and not placing TV in children's bedrooms may be important targets for future obesity prevention initiatives in disadvantaged communities.

On the strength of dislocation interactions and their effect on latent hardening in pure Magnesium

This study is dedicated to the quantification of latent hardening and its effect on the plasticity of pure hexagonal magnesium. To this end, discrete dislocation dynamics simulations are used to (1) extract latent hardening parameters coupling different slip systems, and to (2) assess the validity of two existing constitutive models linking slip system strength to dislocation densities on all slip systems. As hexagonal materials deform via activation of different slip modes, each with different mobilities and lattice friction stress, the effects of the latter on latent hardening evolution are also investigated. It is found that the multi-slip formulation proposed by Franciosi and Zaoui gives accurate predictions when multiple interactions are involved while the formulation suggested by Lavrentev and Pokhil systematically overestimates the flow stress. Similar to FCC materials, it is also found that collinear interactions potentially contribute the most to latent hardening. Basal/pyramidal c + a interactions are found to be very strong, while interactions involving second-order pyramidal c + a primary dislocations appear to be the weakest ones. Finally, the latent hardening parameters, extracted from the discrete dislocation dynamics simulations, are used in polycrystal simulations and the impact of finely accounting for latent hardening on predictions of the macroscopic anisotropic response is shown to be of significant importance.

Infiltração marginal em cavidades de classe V. Efeito de sistema adesivo e preparo cavitário

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Mechanisms of apoptosis in chronic lymphocytic leukemia (CLL)

Chronic lymphocytic leukemia (CLL) is an incurable disease characterized by the accumulation of terminally differentiated, mature B cells that do not progress beyond the G1 stage of cell cycle, suggesting that these cells possess intrinsic defects in apoptosis. Treatment relies heavily on chemotherapy (primarily nucleoside analogs and glucocorticoids) that may initially be effective in patients, but ultimately give rise to refractory, untreatable disease. The purpose of this study was to determine whether key components of the apoptotic machinery were intact in CLL lymphocytes, especially in patients refractory to therapy. ^ Activation of proteases has been shown to be at the core of the apoptotic pathway and this work demonstrates that protease activation is required for glucocorticoid and nucleoside analog-induced apoptosis in CLL cells. Inhibitors of serine proteases as well as caspase inhibitors blocked induced DNA fragmentation, and a peptide inhibitor of the nuclear scaffold (NS) protease completely suppressed both induced and spontaneous apoptosis. However, the NS protease inhibitor actually promoted several pro-apoptotic events, such as caspase activation, exposure of surface phosphatidylserine, and loss of mitochondrial membrane potential. These results suggested that the NS protease may interact with the apoptotic program in CLL cells at two separate points. ^ In order to further investigate the role of the NS protease in CLL, patient isolates were treated with proteasome inhibitors because of previous results suggesting that the ISIS protease might be a β subunit of the proteasome. Proteasome inhibitors induced massive DNA fragmentation in every patient tested, even in those resistant to the effects of glucocorticoid and nucleoside analogs in vitro. Several other features of apoptosis were also promoted by the proteasome inhibitor, including mitochondrial alterations such as release of cytochrome c and drops in mitochondrial membrane potential. Proteasome inhibitor-induced apoptosis was associated with inhibition of NFκB, a proteasome-regulated transcription factor that has been implicated in the suppression of apoptosis in a number of systems. The NS protease inhibitor also caused a decrease in active NFκB, suggesting that the proapoptotic effects of this agent might be due to depletion of NFκB. ^ Given these findings, the role of NFκB, in conferring survival in CLL was investigated. Glucocorticoid hormone treatment was shown to cause decreases in the activity of the transcription factor, while phorbol dibutyrate, which blocks glucocorticoid-induced DNA fragmentation, was capable of upregulating NFκB. Compellingly, introduction of an undegradable form of the constitutive NFκB inhibitor, IκB, caused DNA fragmentation in several patient isolates, some of which were resistant to glucocorticoid in vitro. Transcription of anti-apoptotic proteins by NFκB was postulated to be responsible for its effects on survival, but Bcl-2 levels did not fluctuate with glucocorticoid or proteasome inhibitor treatment. ^ The in vitro values generated from these studies were organized into a database containing numbers for over 250 patients. Correlation of relevant clinical parameters revealed that levels of spontaneous apoptosis in vitro differ significantly between Rai stages. Importantly, in vitro resistance to nucleoside analogs or glucocorticoids predicted resistance to chemotherapy in vivo, and inability to achieve remission. ^