Microstructural characterization of medical-grade stainless steel powders prepared by mechanical alloying and subsequent annealing

Cataloged from PDF version of article.The harmful effect of nickel ions released from conventional stainless steel implants has provided a high level of motivation for the further development of nickel-free stainless steels. In this paper, the microstructure of medical-grade nickel-free stainless steel powders, with the chemical composition of ASTM F2581, is studied during mechanical alloying and subsequent annealing. Rietveld X-ray diffraction and transmission electron microscopy evaluations reflect nanocrystallization, austenitization and amorphization of the powders due to mechanical activation. It is also realized that annealing of the as-milled powder can develop a single austenitic structure with nanometric crystallite sizes, implying a considerable inherent resistance to grain growth. This study demonstrates the merit of mechanical alloying and subsequent annealing in the development of nanostructured medical-grade stainless steels. (C) 2012 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserve

Physiological effects of proinsulin-connecting peptide in human subcutaneous adipose tissue

Recent studies suggest that proinsulin-connecting peptide (C-peptide) may exhibit characteristics of a hormone and show physiological functions in various tissues. This study was aimed to determine whether C-peptide could be involved in the regulation of lipolysis, adiponectin release, and function of mesenchymal stem cells (MSCs) in adipose tissue. Human subcutaneous adipose tissue was cultured in the presence of C-peptide. The level of lipolysis was determined by glycerol measurement in the conditioned media. Effect of C-peptide on adiponectin secretion was evaluated in differentiated adipocytes. The adipogenic and osteogenic abilities of adipose MSCs were evaluated using oil red and alizarin red staining, respectively. The tetrazolium bromide test was conducted for evaluating the effect of C-peptide on MSCs proliferation. C-peptide induced a significant decrease in basal lipolysis at concentrations of 8 and 16 nM (p < 0.05). It had no significant effects on isoproterenol-stimulated lipolysis, adiponectin secretion, and adipogenic or osteogenic differentiation of MSCs. At a concentration of 4 nM, this peptide significantly increased the proliferative capability of MSCs (p < 0.05). These results suggest that C-peptide has some physiological effects in human subcutaneous adipose tissue and contributes to the regulation of basal lipolysis and pool of MSCs

Realism and the wave-function

Realism -- the idea that the concepts in physical theories refer to 'things' existing in the real world -- is introduced as a tool to analyze the status of the wave-function. Although the physical entities are recognized by the existence of invariant quantities, examples from classical and quantum physics suggest that not all the theoretical terms refer to the entities: some terms refer to properties of the entities, and some terms have only an epistemic function. In particular, it is argued that the wave-function may be written in terms of classical non-referring and epistemic terms. The implications for realist interpretations of quantum mechanics and on the teaching of quantum physics are examined.Comment: No figure

3D-printed microfluidic droplet generation systems for drug delivery applications

Drug delivery systems are advanced methods that aim to deliver a targeted drug to a specific location or release it at a controlled rate. Many methods have been proposed for drug delivery systems, among which microfluidic systems present unique advantages. In contrast to bulk methods, in this work, by considering the unique capacity of microfluidic-based drug delivery systems, including controllability of fabricated chip geometry and flow rate of multiphase fluid, highly stable particles with higher encapsulation efficiency can be generated. Employing additive manufacturing in biomedical applications has enabled researchers to propose novel and accurate microfluidic systems. In this paper, by employing stereolithography (SLA) and fused deposition modeling (FDM) 3D printing, a microfluidic-based drug delivery system for generating polycaprolactone (PCL) droplets loaded with dexamethasone drug is fabricated. Scanning electron microscope (SEM) images and microscopic images show the effectiveness of this method in generating such droplets

Microstructural characterization of medical-grade stainless steel powders prepared by mechanical alloying and subsequent annealing

The harmful effect of nickel ions released from conventional stainless steel implants has provided a high level of motivation for the further development of nickel-free stainless steels. In this paper, the microstructure of medical-grade nickel-free stainless steel powders, with the chemical composition of ASTM F2581, is studied during mechanical alloying and subsequent annealing. Rietveld X-ray diffraction and transmission electron microscopy evaluations reflect nanocrystallization, austenitization and amorphization of the powders due to mechanical activation. It is also realized that annealing of the as-milled powder can develop a single austenitic structure with nanometric crystallite sizes, implying a considerable inherent resistance to grain growth. This study demonstrates the merit of mechanical alloying and subsequent annealing in the development of nanostructured medical-grade stainless steels. © 2013 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved

Associations between fruit and vegetable intake, leisure-time physical activity, sitting time and self-rated health among older adults : cross-sectional data from the WELL study

BackgroundLifestyle behaviours, such as healthy diet, physical activity and sedentary behaviour, are key elements of healthy ageing and important modifiable risk factors in the prevention of chronic diseases. Little is known about the relationship between these behaviours in older adults. The purpose of this study was to explore the relationship between fruit and vegetable (F&amp;V) intake, leisure-time physical activity (LTPA) and sitting time (ST), and their association with self-rated health in older adults.MethodsThis cross-sectional study comprised 3,644 older adults (48% men) aged 55-65 years, who participated in the Wellbeing, Eating and Exercise for a Long Life (&quot;WELL&quot;) study. Respondents completed a postal survey about their health and their eating and physical activity behaviours in 2010 (38% response rate). Spearman\u27s coefficient (rho) was used to evaluate the relationship between F&amp;V intake, LTPA and ST. Their individual and shared associations with self-rated health were examined using ordinal logistic regression models, stratified by sex and adjusted for confounders (BMI, smoking, long-term illness and socio-demographic characteristics).ResultsThe correlations between F&amp;V intake, LTPA and ST were low. F&amp;V intake and LTPA were positively associated with self-rated health. Each additional serving of F&amp;V or MET-hour of LTPA were associated with approximately 10% higher likelihood of reporting health as good or better among women and men. The association between ST and self-rated health was not significant in the multivariate analysis. A significant interaction was found (ST*F&amp;V intake). The effect of F&amp;V intake on self-rated health increased with increasing ST in women, whereas the effect decreased with increasing ST in men.ConclusionThis study contributes to the scarce literature related to lifestyle behaviours and their association with health indicators among older adults. The findings suggest that a modest increase in F&amp;V intake, or LTPA could have a marked effect on the health of older adults. Further research is needed to fully understand the correlates and determinants of lifestyle behaviours, particularly sitting time, in this age group

Risk factor investigation for cardiovascular health through WHO STEPS approach in Ardabil, Iran

Objectives: Reliable evidence is the keystone for any noncommunicable disease (NCD) prevention plan to be initiated. In this study we carried out a risk factor investigation based on the WHO Stepwise approach to Surveillance (STEPS). Methods: The study was conducted on 1000 adults between 15 and 64 years of age living in Ardabil province, north-west Iran during 2006, based on the WHO STEPS approach to surveillance of risk factors for NCD. At this stage only the first and second steps were carried out. Data were collected through standard questionnaires and methods analyzed using STATA version 8 statistical software package. Results: 29.0% of men and 2.6% of women were current daily tobacco smokers. The mean number of manufactured cigarettes smoked per day was 18.9 among current daily smokers. Smoking was most prevalent among men of low-income families and those of lower education The mean body mass index (BMI) was 26.6 kg/m2, and was significantly correlated with systolic blood pressure. 58.9% were overweight or obese; 18.0% had raised blood pressure and 3.7% had isolated systolic hypertension. The mean number of servings of fruit consumed per day was 1.1; 33.1% had low levels of activity. Combined risk factor analysis showed that 4.1%of participants were in the low-risk group (up to 5.1% among men and 3.2% among women).Those in the high-risk group comprised 25.6% in the 25- to 44-year age group and 49.7%in the 45- to 64-year age group. Mean BMI increased by age in both sexes at least at the firstthree decades of adult life. Conclusion: Based on observed status of risk for cardiovascular health, burden of cardiovascular diseases is expected to increase if an effective prevention strategy is not undertaken