Solute segregation and texture modification in an extruded magnesium alloy containing gadolinium

The alloy Mg-1.5Gd has been extruded at different temperatures to produce two significantly different textures. At lower extrusion temperatures there was significant solute clustering in the matrix, coupled with segregation of solute to the grain boundaries. At higher temperatures these two phenomena were both less pronounced. It is suggested here that segregation of solute to the grain boundaries plays a significant role in the texture modification effect that rare earth elements have in magnesium alloys.

Structure and thermal stability of natural rubber reinforced with in situ generated zinc sorbate

In situ prepared zinc disorbate (ZDS) in natural rubber (NR) by the reaction of zinc oxide and sorbic acid was used to reinforce the dicumyl peroxide-cured NR vulcanizate. The changes in mechanical properties of NR vulcanizates after ageing and were determined and the structures and thermal stability of vulcanizates were also analyzed using scanning electron microscope and thermal gravimetric analyzer. The change ratios in tensile strength and elongation at break of NR vulcanizate with theoretic formation of ZDS of 21phr can be increased to -33 from -44 and -27 from -38 after ageing and the initial weight loss temperature of NR vulcanizate can be increased for about 7°C as compared to un-reinforced NR vulcanizate, indicating that the antioxidative behavior and thermal stability of NR can be improved significantly with theoretic formation of ZDS of 21phr.

Apical localization of zinc transporter ZnT4 in human airway epithelial cells and its loss in a murine model of allergic airway inflammation

The apical cytoplasm of airway epithelium (AE) contains abundant labile zinc (Zn) ions that are involved in the protection of AE from oxidants and inhaled noxious substances. A major question is how dietary Zn traffics to this compartment. In rat airways, in vivo selenite autometallographic (Se-AMG)-electron microscopy revealed labile Zn-selenium nanocrystals in structures resembling secretory vesicles in the apical cytoplasm. This observation was consistent with the starry-sky Zinquin fluorescence staining of labile Zn ions confined to the same region. The vesicular Zn transporter ZnT4 was likewise prominent in both the apical and basal parts of the epithelium both in rodent and human AE, although the apical pools were more obvious. Expression of ZnT4 mRNA was unaffected by changes in the extracellular Zn concentration. However, levels increased 3-fold during growth of cells in air liquid interface cultures and decreased sharply in the presence of retinoic acid. When comparing nasal versus bronchial human AE cells, there were significant positive correlations between levels of ZnT4 from the same subject, suggesting that nasal brushings may allow monitoring of airway Zn transporter expression. Finally, there were marked losses of both basally-located ZnT4 protein and labile Zn in the bronchial epithelium of mice with allergic airway inflammation. This study is the first to describe co-localization of zinc vesicles with the specific zinc transporter ZnT4 in airway epithelium and loss of ZnT4 protein in inflamed airways. Direct evidence that ZnT4 regulates Zn levels in the epithelium still needs to be provided. We speculate that ZnT4 is an important regulator of zinc ion accumulation in secretory apical vesicles and that the loss of labile Zn and ZnT4 in airway inflammation contributes to AE vulnerability in diseases such as asthma.

Blood mineral, trace-element and vitamin concentrations in Huacaya alpacas and Merino sheep grazing the same pasture

We aimed to determine whether the concentration of minerals and trace constituents in blood of Merino sheep and Huacaya alpacas grazing the same pasture differed with species and time of sampling. Blood samples and pasture samples were collected at frequent intervals over a period of 2 years for mineral and trace-nutrient assay. The concentration of the minerals and trace nutrients in the grazed pasture usually met the dietary needs of sheep at maintenance, apart from potassium, sulfur, cobalt and Vitamin E in occasional samples. Restricted maximum likelihood mixed model analysis indicated a significant (P < 0.001) species by month by year interaction for all blood constituents assayed, a significant (P < 0.05) species by coat shade interaction for plasma Vitamin D, E and B12 and a significant (P < 0.001) species by month by Vitamin D interaction for plasma phosphorus concentrations. In general, plasma calcium concentrations were greater in sheep than in alpacas but plasma magnesium concentrations were greater in alpacas than in sheep. There was no consistent difference between the two species in plasma phosphorus concentrations although low values were recorded in individual sheep and alpacas. Plasma Vitamin D concentrations were more responsive to increasing hours of sunlight in alpacas than they were in sheep. Sheep had consistently higher concentrations of plasma copper, zinc and Vitamin B12 and higher concentrations of blood selenium but lower concentrations of plasma selenium and Vitamin A, than did alpacas. No consistent difference was observed between the two species in plasma Vitamin E concentrations.

Corrosion of heat treated magnesium alloy ZE41

This paper investigates the effect of heat treatment upon the corrosion morphology and mechanism of ZE41 alloy. The results of optical and scanning electron microscopy (SEM) together with potentiodynamic polarisation reveal the importance of the microstructure in the initiation and propagation of corrosion in an aqueous environment. The corrosion of the heat-treated alloy is significantly altered due to changes in the microstructure, specifically the Zr-rich regions and the grain boundary T-phase.

Sensitivity of deformation twinning to grain size in titanium and magnesium

The impact of grain size on deformation twinning in commercial purity titanium and magnesium alloy Mg–3Al–1Zn (AZ31) is investigated. Tensile tests were carried out for the titanium samples; compression testing was employed for the magnesium specimens. Average values of the true twin length, true twin thickness and the number density of twins were determined using stereology. A key difference between these two materials is that twinning contributes little to the plastic strain in the titanium while it accounts for nearly all of the early plastic strain in the magnesium. In some respects (e.g. volume fraction and number density) the phenomenology of twinning differed between the two materials, while in others (e.g. twin shape and size) both materials showed a similar response. It is found that in both materials, twins span the entirety of their parent grains only for grain sizes less than ∼30 μm. Both the nucleation density per unit of nucleating interface (i.e. grain and twin boundaries) and the aspect ratio of twins scale with applied stress. The impact of grain size on twin volume fraction is modelled analytically.

Micronutrient intakes affect early growth in extremely preterm infants : preliminary results from a Swedish cohort

Background: Extremely preterm infants generally experience postnatal growth failure. It is still unclear if this is related to micronutrient intakes.

Aim: To investigate the effect of micronutrient intakes (calcium, zinc, iron, phosphorus, sodium, potassium, chloride, magnesium, vitamin A, vitamin D, vitamin E, folate and vitamin B12) on growth during the first 28 days of life in extremely preterm infants.

Method: From the EXPRESS cohort (all infants born < 27 gestational weeks between 2004-2007 in Sweden), those who survived the first 28 days were included (n=524). Daily parenteral and enteral intakes and anthropometric measurements were retrieved from hospital records.

Results: Preliminary analyses of data from 333 infants (mean±SD gestational age 25.2±1.0 weeks, birth weight 753±168g) showed that macronutrient intakes were lower than recommended (energy 98±13kcal/kg/day, protein 2.9±0.4g/kg/day). Infants showed postnatal growth failure: mean standard deviation scores decreased by 2.2 for weight, 2.3 for length and 1.4 for head circumference. Intakes of micronutrients were generally low, e.g. adjusted enteral intakes of calcium were 66.6±21.4 mg/kg/day. The exception was iron, with a high parenteral intake of 2.7±1.6 mg/kg/day, mainly from blood transfusions. Adjusting for protein intake and other confounders, calcium intakes were positively correlated with head growth (r=+0.19, p=0.006) and iron intakes were negatively correlated with length gain (r=-0.18, p=0.009).

Conclusions: Low calcium intakes and high iron intakes were associated with poor growth with regard to head circumference and length, respectively. If these results are confirmed, optimized micronutrient intakes may improve early growth in extremely preterm infants.

Effect of grain size on deformation twinning in a magnesium alloy and commercial purity titanium

This data collection contains several optical microstructure images, EBSD maps and stress-strain curves. The research involves collecting data from samples with different grain sizes at several values of plastic strains to measure some important twinning parameters such as twin volume fraction and number of twins per grain. The aim of this study is to investigate the effect of grain size on deformation twinning behaviour in two hcp metals i.e. commercial purity titanium and AZ31 magnesium alloy.