Strong morphological and crystallographic texture and resulting yield strength anisotropy in selective laser melted tantalum

Selective laser melting (SLM) makes use of a high energy density laser beam to melt successive layers of metallic powders in order to create functional parts. The energy density of the laser is high enough to melt refractory metals like Ta and produce mechanically sound parts. Furthermore, the localized heat input causes a strong directional cooling and solidification. Epitaxial growth due to partial remelting of the previous layer, competitive growth mechanism and a specific global direction of heat flow during SLM of Ta result in the formation of long columnar grains with a 〈1 1 1〉 preferential crystal orientation along the building direction. The microstructure was visualized using both optical and scanning electron microscopy equipped with electron backscattered diffraction and the global crystallographic texture was measured using X-ray diffraction. The thermal profile around the melt pool was modeled using a pragmatic model for SLM. Furthermore, rotation of the scanning direction between different layers was seen to promote the competitive growth. As a result, the texture strength increased to as large as 4.7 for rotating the scanning direction 90° every layer. By comparison of the yield strength measured by compression tests in different orientations and the averaged Taylor factor calculated using the viscoplastic self-consistent model, it was found that both the morphological and crystallographic texture observed in SLM Ta contribute to yield strength anisotropy.     

Influence of the charge density of cationic polyelectrolytes on sludge conditioning

Commercial polyelectrolytes, generally used for sludge conditioning, are poorly characterized as far as the charge density is concerned. Five cationic polyelectrolytes at different strength, having similar molecular weight (1–5 million), were selected. Their charge densities were measured by a conductometric method and found to be between 1.5 and 3.7 mequiv g^?1. These polymers were used for conditioning five different sludges produced in full-scale wastewater treatment plants and the optimal doses were correlated to the sludge concentration taking into account the values of the charge density. The quite good correlation found, according to the theory of charge neutralization of colloids of opposite sign, seems to be a useful criterion for predicting the optimum polyelectrolyte dose for sludge conditioning.     

Radical prostatectomy and prognostic factors

We investigated ectopic bone formation by biphasic calcium phosphate (BCP) combined with recombinant human bone morphogenetic protein-2 (rhBMP-2) in the rat dorsum. Under reduced pressure, rhBMP-2 was adsorbed onto BCP, which consisted of 80% beta-tricalcium phosphate and 20% hydroxyapatite uniformly distributed in granules. Twenty Wistar rats were separated into 4 groups consisting of 5 animals each dosed with 2, 10, and 50 micrograms/700 microliters of rhBMP-2 and a control group (BCP only). Pieces of the BCP-BMP complex or only BCP were implanted under the dorsal skin of the rats. Histological sections were examined three weeks later. New bone was formed in all rats given 50 micrograms doses, but not in the 2 micrograms and control groups. These results indicated that BCP combined with rhBMP-2 induced ectopic bone formation without additional carriers. Therefore, BCP granules alone can function as carriers for rhBMP-2 to induce bone formation.     

Aggression and social experience in domesticated rats.

Conducted an experiment with 48 male and 28 female Long-Evans rats. Small colonies were established, using adult Ss that had either received continuous social experience or had been isolated since weaning. Unfamiliar intruder rats-with or without postweaning social experience-were exposed individually to the colonies for a 21-hr period. Behavioral observations and an assessment of the intruder's physical condition indicated that serious fighting, physical injuries, and large weight losses occurred only when an isolation-reared intruder was placed into a colony of socially experienced Ss. Results demonstrate that aggression is a joint function of the rearing history of both the colony and the intruder and that social experience plays an important role in the behavioral development of this species. (24 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dünne PVD-Hartstoffschichten zur Online-Temperaturmessung

Thin PVD hard coatings for the online temperature measurement In the processing industry, process control and the improvement of manufacturing processes become increasingly important. Therefore the acquisition of important process data during production becomes the focus of attention. Physical Vapor Deposition (PVD) allows the deposition of only a few micrometers thin coatings, which follow the shape of the coated surface. They have functionalities and can also increase the wear and corrosion resistance of the coated production tool or components. The aim of this article was the development of thin PVD coatings which can measure temperatures ranging from room temperature up to several hundred centigrades. Therefore, two different coating systems are presented and analyzed with regard to their suitability for temperature measurement. The overall aim is intended to measure the temperature in the interface between the tool surface and the processed workpiece in cutting process or between the tool surface and the melt by primary forming. The sensor coating provides the possibility of an online temperature measurement and the forwarding of this process data. The operating principle is based on the thermoelectric effect, which is also known as the Seebeck effect.