On the formation of macrosegregations in ingots

A new quenching technique for studying the formation of macrosegregations in ingots has been developed and used in a study of the formation of A-segregations in ingots. The for-mation of a negative segregation in the bottom part of an ingot and a positive segregation in the top part have also been studied. It was found that the three types of macrosegrega-tion phenomena could be explained by the occurrence of interdendritic convection during the solidification process.     

Integrating Statistical and Machine-Learning Approach for Meta-Analysis of Bisphenol A-Exposure Datasets Reveals Effects on Mouse Gene Expression within Pathways of Apoptosis and Cell Survival

Bisphenols are important environmental pollutants that are extensively studied due to different detrimental effects, while the molecular mechanisms behind these effects are less well understood. Like other environmental pollutants, bisphenols are being tested in various experimental models, creating large expression datasets found in open access storage. The meta-analysis of such datasets is, however, very complicated for various reasons. Here, we developed an integrating statistical and machine-learning model approach for the meta-analysis of bisphenol A (BPA) exposure datasets from different mouse tissues. We constructed three joint datasets following three different strategies for dataset integration: in particular, using all common genes from the datasets, uncorrelated, and not co-expressed genes, respectively. By applying machine learning methods to these datasets, we identified genes whose expression was significantly affected in all of the BPA microanalysis data tested; those involved in the regulation of cell survival include: Tnfr2, Hgf-Met, Agtr1a, Bdkrb2; signaling through Mapk8 (Jnk1)); DNA repair (Hgf-Met, Mgmt); apoptosis (Tmbim6, Bcl2, Apaf1); and cellular junctions (F11r, Cldnd1, Ctnd1 and Yes1). Our results highlight the benefit of combining existing datasets for the integrated analysis of a specific topic when individual datasets are limited in size.     

TEM-, SEM- and STEM-studies of sputter-coated cytoskeletons

A technique for sputter coating of cytoskeletons from detergent extracted cells is described. The method allows their study in high resolution TEM, SEM and STEM. The use of cytoskeletons is also a valuable model system for the evaluation of metal coating techniques, allowing studies of deposited metal on fine filamentous structures of varying thicknesses. Pt and W were sputtered at 1 to 5 nm, and comparisons were made with reference to contrast and granularity. Both metais gave good topographical contrast, but Pt showed a coarse structure and a greater decorating tendency than W. The method provides a simple system for studies of the three-dimensional cytoskeletal organization, without the use of cumbersome replica-techniques.     

Laboratory work with automatic pipettes: a study on how pipetting affects the thumb

The aim of this study was to assess the strain that is exerted on the thumb when working with automatic pipettes. The study consisted of three parts: a survey concerning stress-related symptoms in general and in the thumb in particular, a study of the working conditions in the laboratory with the help of a video-film, and a power test. In the survey the Nordic Council of Ministers' questionnaire and a newly developed questionnaire about the thumb were used. A usual and frequently carried out analysis that included several different methods of pipetting was filmed on video. The power test measured two things, the power that is necessary to press down the button of the pipette into different positions and the maximal strength when performing a movement in the same direction. It was shown that the strain on the thumb for a woman with weak muscular structures is unacceptably high. The symptoms increase with the amount of time spent with pipetting and with age. In addition, pipetting is done in a position where the thumb is not stable but nevertheless has to work to stabilize the grip around the pipette and to press down the button of the pipette. Therefore the muscles have to work both as mobilizing and stabilizing structures. It is concluded, therefore, that some form of automation ought to be taken into consideration if the amount of pipetting work tends to increase. The pipettes should be constructed with as little button resistance as possible and the handle should be designed to fit different hand sizes.     

Volume change during the solidification of grey cast iron: its relation with the microstructural variation,comparison between experimental and theoretical analysis

The expansion/contraction during the solidification of grey cast iron was studied using Linear Variable Differential Transformer (LVDT). The experiments were conducted with and without melt treatment. Two types of inoculant used for melt treatment: ASSC (Si, Ca, Sr & Al) and MBZCAS (Si, Ca, Zr, Ba, Mn & Al). Microstructural investigations carried out to quantify the eutectic cells, undercooled graphite, primary austenite and secondary dendritic arm spacing (SDAS). It was found that the casting shows hardly any shrinkage during early solidification but in the eutectic region, the casting expands until the end of solidification. The measured and the calculated volume changes are close to one another, but the former shows more expansion. The addition of MBZCAS promotes more flake graphite, and ASSC does not increase eutectic cells much. In addition to that, it lowers the primary austenite fraction, promotes more eutectic growth, decreases undercooled graphite and SDAS. As a result, the volume expansion changes in the eutectic region.     

A study of a flexible fiber model and its behavior in DNS of turbulent channel flow

The dynamics of individual flexible fibers in a turbulent flow field have been analyzed, varying their initial position, density and length. A particle-level fiber model has been integrated into a general-purpose, open source computational fluid dynamics code. The fibers are modeled as chains of cylindrical segments connected by ball and socket joints. The equations of motion of the fibers contain the inertia of the segments, the contributions from hydrodynamic forces and torques, and the connectivity forces at the joints. Direct numerical simulation of the incompressible Navier–Stokes equations is used to describe the fluid flow in a plane channel, and a one-way coupling is considered between the fibers and the fluid phase. We investigate the translational motion of fibers by considering the mean square displacement of their trajectories. We find that the fiber motion is primarily governed by velocity correlations of the flow fluctuations. In addition, we show that there is a clear tendency of the thread-like fibers to evolve into complex geometrical configurations in a turbulent flow field, in fashion similar to random conformations of polymer strands subjected to thermal fluctuations in a suspension. Finally, we show that fiber inertia has a significant impact on reorientation timescales of fibers suspended in a turbulent flow field.     

Solvent-assisted trypsin digestion of ricin for forensic identification by LC-ESI MS/MS

The castor bean plant (Ricinus communis) is used in large quantities for oil production and is also a common ornamental garden plant. However, the beans contain 1-3% of the highly toxic protein ricin, a type II ribosome-inactivating protein that is covered by the Chemical Weapons Convention, and there have been a number of reports concerning the use, or alleged use, of the toxin in terrorist and criminal activities. In the study reported here, we investigated the potential utility of organic solvent-assisted trypsin digestion of crude extracts containing the closely related toxins ricin or abrin to prepare samples for peptide analysis by liquid chromatography combined with electrospray ionization quadrupole time-of-flight tandem mass spectrometry. Diagnostic tryptic fragments of the toxins were detected and unambiguously identified by this procedure. The sample preparation protocol substantially reduces the sample preparation time, from overnight to an hour, and thus greatly reduces the total time required for analyses, to less than 2 h. Furthermore, the reported procedure leaves the disulfide bonds in the protein intact. This is highly relevant in the context of the Chemical Weapons Convention, since the disulfide bond connecting the two chains of ricin indicates the presence of an intact toxin and provides additional forensic evidence for the analytical results.     

Thermodynamic Activities of “FeO” in some Binary “FeO”‐Containing Slags

In the present investigation, experimental measurements of the thermodynamic activities of iron oxide in the Al₂O₃‐“FeO”, CaO‐“FeO” and “FeO”‐SiO₂ systems were performed in the temperature range 1823‐1873 K by using gas equilibration technique. The molten slag, kept in a Pt‐crucible was brought to equilibrium with a gas mixture of known oxygen partial pressure. A part of the Fe from the “FeO” was reduced during the equilibration and got dissolved in the Pt phase. The samples were quenched after the required equilibration time and the slag phase as well as the platinum crucible was subjected to chemical analysis. The activities of “FeO” in the slag were calculated from the experimental data using thermodynamic information on the Fe‐Pt binary metallic system generated and assessed earlier. The experimental results are compared with earlier thermodynamic studies of the slag systems. Reassessment with the KTH slag model is performed and the results are compared with other thermodynamic models, viz. F*A*C*T? and Thermo‐Calc? respectively. The experimental activities predicted by the KTH slag model are in good agreement with the experimental data available in the literature. A general agreement between the various models is also observed.     

Fat oxidation at low oxygen pressure. i. kinetic studies on the rate of fat oxidation in emulsions

Oxidation was measured by oxygen consump-tion in a Warburg apparatus, modified to main-tain constant partial oxygen pressure by auto-matic electrolytic generation of oxygen with automatic recording of the oxygen consumed. The decrease in rate of oxygen consumption on the lowering of partial oxygen pressure at at-mospheric pressure was found to depend on a) the varying influence of the nonoxygen-dependent and the oxygen-dependent reactions of the prop-agation which may vary with the conditions such as the reactivity of the substrate, the tem-perature, and the pH value but which is not affected by light irradiation; b) the varying rate-limiting effect of slow oxygen diffusion, depending on the ratio between the rate of oxidation and the rate of oxygen diffusion.