Chaperone‐like activity of β‐casein and its effect on residual in vitro activity of horseradish peroxidase

In this study, the residual activity horseradish peroxidase was used as a novel marker of chaperone‐like activity of β‐casein under elevated temperature. It was shown that β‐casein does affect residual activity of horseradish peroxidase (HRP) depending on the concentration and molar ratio between proteins. Incubating HRP (0.1 mg mL^?1) for 10 min at 72 °C resulted in residual activity of 59 ± 5%, while addition of 1 mg mL^?1 β‐casein resulted in increase in residual activity up to 85 ± 1%. Increased residual activity is not merely attributed to an effect of higher total protein concentration, as similar experiment with bovine serum albumin resulted in residual activity of horseradish peroxidase that was significantly lower than without any addition. The effect of β‐casein on HRP disappears when pH is below the isoelectric point of β‐casein. It was also proven by light scattering studies that β‐casein interacts with horseradish peroxidase when the temperature was increased from 25 to 70 °C whereas interactions seem to cease when temperature was lowered back to 25 °C. This study highlights how specific proteins can influence enzyme activity, which is of potential importance for various industries such as enzyme manufacturers and food industry.     

Experimental difficulties associated with permeability measurements in aluminum alloys

The general principles and experimental difficulties associated with the measurement of permeability in aluminum alloys have been discussed, in order to ease the further development of experimental methods suitable for such measurements. In order to avoid the surface-tension effects associated with liquid/gas interfaces in the narrow channels of the mushy zone, a flux melt can be used at the inlet of the permeameter. Electron-beam (EB) welding has been shown to be a suitable method for ensuring a complete wetting between the sample and flux after remelting to the test temperature. Moreover, the influence of the permeameter design and the experimental procedure on grain detachment, preferred-flow channel formation, and coarsening have been revealed through microstructural images.     

The use of satellite images for mapping of landscape and biological diversity in the Sahel

The use of satellite images for mapping landscape and biological diversity in the Ferlo region of Senegal, in the Sahel ecoclimatic zone, was tested. A high resolution Landsat TM image was used for measurements of the landscape diversity. NOAA INDVI was applied for a yearly assessment of biomass production. These data were later correlated with avian diversity, which was used as an indicator of biological diversity. A model based on a combination of the two types of satellite images was used to explain 40-50 per cent of the variations in bird populations in the winters of 1991-1992 and 1992-1993. The model is suggested as a preliminary assessment for mapping and monitoring biological diversity in landscapes with large heterogeneity in the horizontal plane like the Sahel region.     

Precision bending of high-quality components for volume applications

Recent new technology developments were presented in the field of industrial bending operations, including flexible stretch forming and 3D rotary stretch forming. Attempts were made to give an overview of different mechanisms that influence dimensional accuracy, including local cross-sectional deformations such as suck-in and volume conservation effects, along with global deformations such as springback. An analytical model was developed to determine the particular influence of different material, geometry and process parameters on dimensional variability of bent components. The results were discussed in terms of overall process capability (C_p) and associated process windows. The results show that different governing mechanisms prevail in various bending operations, meaning that attention has to be placed on controlling those process parameters that really are important to part quality in each specific case. Several strategies may be defined for reducing variability. One alternative may be to design more robust process and tool technology that reduce the effect of upstream parameters on dimensional variability of the formed part. The results show that optimal tool design and technology may in specific cases improve the dimensional accuracy of a formed part. Based on the findings discussed herein, it is concluded that advances in industrial bending operations require focus on improving the understanding of mechanical mechanisms, including models and parameter development, new technology developments, including process, tool, measurement and control capabilities, and process discipline at the shop floor, combined with a basic philosophy of controlling process parameters rather than part attributes.     

Proteomic Comparison of Bone Marrow Derived Osteoblasts and Mesenchymal Stem Cells

Mesenchymal stem cells (MSCs) can differentiate into osteoblasts, and therapeutic targeting of these cells is considered both for malignant and non-malignant diseases. We analyzed global proteomic profiles for osteoblasts derived from ten and MSCs from six healthy individuals, and we quantified 5465 proteins for the osteoblasts and 5420 proteins for the MSCs. There was a large overlap in the profiles for the two cell types; 156 proteins were quantified only in osteoblasts and 111 proteins only for the MSCs. The osteoblast-specific proteins included several extracellular matrix proteins and a network including 27 proteins that influence intracellular signaling (Wnt/Notch/Bone morphogenic protein pathways) and bone mineralization. The osteoblasts and MSCs showed only minor age- and sex-dependent proteomic differences. Finally, the osteoblast and MSC proteomic profiles were altered by ex vivo culture in serum-free media. We conclude that although the proteomic profiles of osteoblasts and MSCs show many similarities, we identified several osteoblast-specific extracellular matrix proteins and an osteoblast-specific intracellular signaling network. Therapeutic targeting of these proteins will possibly have minor effects on MSCs. Furthermore, the use of ex vivo cultured osteoblasts/MSCs in clinical medicine will require careful standardization of the ex vivo handling of the cells.     

Influence of Water Vapor on the Response of Mg-Doped SrTio3 Ceramic Oxygen Sensors

Mg-doped SrTio₃ thick film sensors fabricated by screen-printing proved to be very promising for the use as oxygen sensors. A study of the influence of water on the response of these sensors gives an important basis for understanding their behavior in practical applications. The influence of water on the sensor response was measured in the oxygen partial pressure region from air (0.21 bar) to pure N₂ (2.5 × 10^–5)and the temperature range from 600 to 800°C. The relative humidity was varied from 1 to 95% RH. The resistance variation as a function of temperature and the activation energy were evaluated under different dry and wet conditions. The results obtained show that the resistance of these sensors generally decreases with increasing water content in the carrier gas and that the effect of water was strongest at lower temperatures as well as at lower oxygen pressures. To explain this behavior, it is proposed that a partial proton conduction is introduced in the water-containing atmospheres and that this contributes to the total conductivity leading to a reduction of the total resistance. Finally, the measurements also show that the response of these sensors still depends on the oxygen partial pressure according to the standard expression even in the presence of water vapor. Therefore, these sensors can still be used as oxygen sensors in humid atmospheres.     

Processing of ThO2/CeO2 Ceramic Fuel

The paper describes an effective procedure for mixing and conditioning ThO₂ and CeO₂ powders so they are suited for pressing and sintering into high‐density (Th_0.9,Ce_0.1)O₂ ceramic pellets – this material being a “pilot” for (Th,Pu)O₂ fuels. Wet ball milling with an organic dispersant aided the powder dispersing process by reducing the agglomeration of very small oxide particles. Homogeneous elemental distributions were seen within the calcined powder mixture. Heat treatments were applied to the calcined, mixed ThO₂/CeO₂ mix to study phase and surface area transformations. Solid solution formation commences at around 1300°C and goes to completion at a temperature of 1500°C. We also report the effect of a granulation strategy that can be applied to the production of high quality, mixed ThO₂ nuclear fuel ceramics. Sized granules of blended ThO₂/CeO₂ powder were produced from precompacted disks of this material that were subsequently heat treated. This had a positive effect on die filling and compaction into green pellets, as well as on final sintered (Th,Ce)O₂ pellet density. The microstructure of the sintered (Th,Ce)O₂ ceramic was characterized using SEM‐based electron back‐scatter diffraction from which a uniform density and grain size were readily apparent. XRD results showed that a single phase Th_0.9Ce_0.1O₂, fuel ceramic had been produced. Its density was ~94% TD.