Phase selection and microstructure formation in undercooled Co–61.8 at.% Si melts under various containerless processing conditions

The hypoeutectic composition Co–61.8 at.% Si was undercooled and solidified using electromagnetic levitation, electromagnetic levitation under a static magnetic field, electrostatic levitation and glass-fluxing. The samples generally showed two thermal events, either separated or continuous depending on undercooling. In situ monitoring of the two thermal events with a high-speed camera revealed a sudden decrease of dendritic growth velocities of primary phases at a critical undercooling of 88 K. Scanning electron microscopy studies of the solidified samples showed that the CoSi compound and the CoSi₂ compound nucleate as the primary phase for low and high undercoolings, respectively. The microstructure of the samples depends not only on undercooling, but also on the onset temperature or delay time of the second thermal event. Melt convection has no effect on the primary phase selection in undercooled melts, but it has a significant effect on the delay time and therefore on microstructure formation of the samples for high undercoolings.     

Changes in HIV-related information sources, instruction, knowledge, and behaviors among US high school students, 1989 and 1990

The diagnostic values of aminoterminal propeptide of type III procollagen and hyaluronan serum levels were compared as markers of liver fibrosis in two chronic liver diseases of different etiologies and pathophysiologies, namely primary biliary cirrhosis and chronic viral hepatitis C. The results were analysed in terms of the histological extent of fibrosis. Both serum procollagen-III peptide and hyaluronan were elevated in patients with primary biliary cirrhosis and chronic viral hepatitis C (p < 0.0001) relative to control values. A positive correlation was found between serum procollagen-III peptide levels and the histological grade of fibrosis in primary biliary cirrhosis (p < 0.001) but not in chronic viral hepatitis C, while a strong correlation was found between serum hyaluronan levels and histological fibrosis in both primary biliary cirrhosis and chronic viral hepatitis C (p < 0.001), independent of age. These results suggest that, in chronic liver diseases, serum hyaluronan levels could be an important indicator of the extent of fibrosis and should be assayed to monitor the response to treatment in controlled clinical trials.     

Carter-Faktor und Leitwertswellen elektrischer Maschinen mit magnetischem Nutverschluß

Übersicht Zur Berechnung des Carterschen Faktors und der Leitwertswellen wird das skalare Potential des Luftspaltfeldes einer einseitig genuteten Maschine mit Hilfe von Reihenansätzen ermittelt. Der Nutverschluß besteht aus magnetischem Material mit einer vorgegebenen konstanten Permeabilität. Um die Lösung auch für Maschinen mit großem Luftspalt verwenden zu können, wird der Luftspalt in Polarkoordinaten dargestellt.

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Carter's coefficient and permeance waves of electrical machines with magnetic slot wedges

Contents For the purpose of calculating Carter's coefficient and the permeance waves of slotting the scalar potential of the air gap field is computed using Fourier series. The slot wedges consist of magnetic material with a constant permeability. The air gap is described by polar coordinates in order to get solutions applicable to machines possessing a large air gap.

     

Optimized partial-coverage functional analysis pipeline (OPFAP): a semi-automated pipeline for skull stripping and co-registration of partial-coverage,ultra-high-field functional images

Objective

Ultra-high-field functional MRI (UHF-fMRI) allows for higher spatiotemporal resolution imaging. However, higher-resolution imaging entails coverage limitations. Processing partial-coverage images using standard pipelines leads to sub-optimal results. We aimed to develop a simple, semi-automated pipeline for processing partial-coverage UHF-fMRI data using widely used image processing algorithms.

Materials and methods

We developed automated pipelines for optimized skull stripping and co-registration of partial-coverage UHF functional images, using built-in functions of the Centre for Functional Magnetic Resonance Imaging of the Brain's (FMRIB’s) Software library (FSL) and advanced normalization tools. We incorporated the pipelines into the FSL’s functional analysis pipeline and provide a semi-automated optimized partial-coverage functional analysis pipeline (OPFAP).

Results

Compared to the standard pipeline, the OPFAP yielded images with 15 and 30% greater volume of non-zero voxels after skull stripping the functional and anatomical images, respectively (all p =?0.0004), which reflected the conservation of cortical voxels lost when the standard pipeline was used. The OPFAP yielded the greatest Dice and Jaccard coefficients (87 and 80%, respectively; all p <?0.0001) between the co-registered participant gyri maps and the template gyri maps, demonstrating the goodness of the co-registration results. Furthermore, the greatest volume of group-level activation in the most number of functionally relevant regions was observed when the OPFAP was used. Importantly, group-level activations were not observed when using the standard pipeline.

Conclusion

These results suggest that the OPFAP should be used for processing partial-coverage UHF-fMRI data for detecting high-resolution macroscopic blood oxygenation level-dependent activations.

     

Novel insight into microstructural evolution of phase-separated Cu�CCo alloys under influence of forced convection

Cu?CCo alloys of bulk compositions Cu₇₅Co₂₅ and Cu₈₄Co₁₆ were undercooled and solidified using electromagnetic levitation. Microstructure of the samples was characterized using optical microscopy, scanning electron microscopy, energy dispersive spectrometry, and micro X-ray diffraction analysis. It was found that besides a bimodal size distribution, droplets of the Co-rich L₁ phase resulting from liquid phase separation have a broad composition distribution. The bimodal size distribution of the droplets is more pronounced for the Cu₇₅Co₂₅ sample than for the Cu₈₄Co₁₆ sample, whilst the composition distribution of the droplets is broader in the Cu₇₅Co₂₅ sample than in the Cu₈₄Co₁₆ sample. The droplets were found to also have different types of substructures in the two samples. The results provide novel insight into microstructural evolution of phase-separated alloys under influence of forced convection.     

A Mass-Preserving Two-Step Lagrange–Galerkin Scheme for Convection-Diffusion Problems

Journal of Scientific Computing - In this paper, we propose and analyze a mixed finite element scheme for stationary inductionless magnetohydrodynamic equations on a general Lipschitz domain. We...     

Inkjettable conductive adhesive for use in microelectronics and microsystems technology

Ink jet is an accepted technology for dispensing small volumes of material (50–500 picolitres). Currently traditional metal-filled conductive adhesives cannot be processed by ink jetting (owing to their relatively high viscosity and the size of filler material particles). Smallest droplet size achievable by traditional dispensing techniques is in the range of 150 μm, yielding proportionally larger adhesive dots on the substrate. Electrically conductive inks are available on the market with metal particles (gold or silver) <20 nm suspended in a solvent at 30–50 wt%. After deposition, the solvent is eliminated and electrical conductivity is enabled by a high metal ratio in the residue. Some applications include a sintering step. These nano-filled inks do not offer an adhesive function. Work reported here presents materials with both functions, adhesive and conductive. This newly developed silver filled adhesive has been applied successfully by piezo-ink jet and opens a new dimension in electrically conductive adhesives technology.The present work demonstrates feasibility of an inkjettable, isotropically conductive adhesive in the form of a silver loaded resin with a two-step curing mechanism: In the first-step, the adhesive is dispensed (jetted) and precured leaving a ‘dry’ surface. The second step consists of assembly (wetting of the 2nd part) and final curing.     

Direct Assessment of the Creep Strength of DS Cast Turbine Blades Using Miniature Creep Specimens

The present paper presents a novel approach which allows a direct assessment of the creep strength of thin walled DS turbine blades at temperatures up to 1100 °C using a grain morphology sensitive miniature creep specimen test technique. The work builds up on earlier investigations by DeMestral and co-workers ([i] B. DeMestral et al., Met. and Mat. Transactions A, 27A (1996) pp. 879–890 and [ii] B. DeMestral and G. Eggeler, Prakt. Metallogr., 29 (1992) pp. 174–191) on the influence of grain morphology on creep deformation and damage accumulation in superalloys with elongated macrograins. The paper reports the important features of this new procedure which include (i) the creep test technique (specimen geometry and grip design) and (ii) the removal of creep specimens from a DS CM 247 LC cast blade with respect to the morphology of the macrograins. The paper also reports creep results obtained with this new technique at temperature of 1030 °C and a tensile stress of 180 MPa and discusses the results on the basis of the associated microstructural creep deformation and damage mechanisms.