PCPro a Novel Technology for Rapid Prototyping and Rapid Manufacturing

PCPro stands for Precise Cast Prototyping, which is a combination of casting technologies and milling. This method was developed at Fraunhofer IWS in Dresden, Germany. It is patented in Germany [1] and is applied in the USA under US 10/794,936. The main goal for this development was to shorten the process chain for making plastic prototypes accompanied by higher quality. The casting technology was integrated in a machining center in order to enable a high degree of automation and to avoid an external casting system. This means that Rapid Manufacturing can be easily implemented using such an automated combination of casting and machining. This article describes the PCPro method by means of the fabrication of sample parts. The advantages and the limitations in comparison to common Rapid Prototyping and Rapid Manufacturing process chains will be discussed. In addition, the manufacturing of a prototype machine is presented.Mechanical Engineerin

A novel transcriptome subtraction method for the detection of differentially expressed genes in highly complex eukaryotes

We have designed a novel transcriptome subtraction method for the genome-scale analysis of differential gene expression in highly complex eukaryotes, in which suppression subtractive hybridization (SSH) is performed first to enrich the target and, after exchange of adapters, negative subtraction chain (NSC) is then used to eliminate the remaining background. NSC evolved from differential subtraction chain (DSC). We designed novel adapters which make the subtraction system more robust. SSH and NSC were then combined to successfully detect differentially expressed genes in Solanum. The combined technique improves qualitatively upon SSH, the only commercially available transcriptome subtraction system, by detecting target genes in the middle abundance class, to which most differentially expressed genes in highly complex eukaryotes are expected to belong. The main advantage of the combined technique with SSH/NSC is its ability to isolate differentially expressed genes quickly and cost-efficiently from non-standard models, for those microarrays are unavailable

Faster rates of post-puberty kidney deterioration in males is correlated with elevated oxidative stress in males vs females at early puberty

<p>Abstract</p> <p>Background</p> <p>Post-puberty deterioration of kidneys is more rapid in males than in females. To reveal the underlying molecular mechanisms for this difference, we analyzed gender-dependent gene expression in kidneys of three groups of 36 day-old rats.</p> <p>Results</p> <p>The number of genes exhibiting gender-dependent expression was highly influenced by the genetic background of the rat group examined. 373, 288 and 79 genes showed differential gene expression between males and females (p = 0.001) in US, Mhm and Mhm*BN rats, respectively. Of all gender dependently expressed genes, only 39 genes were differentially expressed in all tested groups and the direction of expression change was the same for those genes for all groups. The gene expression profile suggests higher metabolic and transport activities, enhanced cell proliferation, elevated oxidative stress, and altered vascular biology in males. Furthermore, elevated levels of superoxide anion (two- to three-fold) in males compared to females were detected at early puberty, but neither at pre-puberty nor at late puberty/early adulthood.</p> <p>Conclusion</p> <p>Our data suggest that early puberty, with gender-related elevation in oxidative stress in males, is a key compromising factor on kidneys in males.</p

Mechanische Charakterisierung von Laser-Beschichtungen aus WC-verstärkten Hartlegierungen

Schichten aus hartstoffverstärkten Metallegierungen besitzen fast den Verschleißwiderstand von gesintertem Hartmetall. Der erfolgreiche Einsatz dieser Beschichtungen verlangt ihre beanspruchungsnahe Charakterisierung. Entscheidend für das Einsatzverhalten auf Umformwerkzeugen sind vor allem die Haft- und die Schlagfestigkeit. Zur Bestimmung beider Eigenschaften wurden im Fraunhofer IWS entsprechende Prüfverfahren entwickelt, die eine kostengünstige, entwicklungsbegleitende Optimierung der Beschichtungstechnologie ermöglichten. Beide Verfahren können auch zur Charakterisierung anderer Schichtsysteme eingesetzt werden

Herstellung hartmetallähnlicher Verschleißschutzschichten durch Laserauftragsschweißen von Hartstoff-Hartlegierungs-Pulvergemischen

Protective layers exhibiting abrasive wear resistance similare to that of conventional WC/Co hard metal can be repeatably produced by laser cladding using powder mixtures consisting of hard material and binder components. As an advantage compared to sintered hard metals, the claddings can be immediately applied to the load bearing faces. Strong bonding to the base material can be achieved. Unlike sintered hard metal, the claddings show maximum wear resistence with non- dissolved hard material contents as low as 40-50 percent. Thus the claddings are rather ductile, which implies higher resistence to fatigue, impact, and thermal shock. The optimized WC/Co-NiBSi system performs best results with respect to wear, flaws, and cost. Fused tungsten carbide exhibits equivalent wear resistance but the layers may be flawed. Claddings with Stellite 21 binder show minimum wear at contents of 35 vol percent hard material, though cracking and debonding spoil the over-all performance. Based on solid k nowledge derived from work on processing and materials technology, the laser cladding technique described here is ready for industrial application

Suppression of the development of pores during laser-induced surface dispersion of TiC into aluminium, by means of a static magnetic field

A static magnetic field having the strength of B=0.6 T has been used as an additional process parameter in order to suppress the establishment of pores while dispersing TiC particles in surface layers of aluminium alloys using a laser. The migration of hydrogen towards regions of high temperatures within the melting pool can lead to the creation of gas bubbles, therefore yielding pores after resolidification in the processed layer. This mechanism (known for instance in welding technologies of aluminium) could be suppressed by Lorentz-forces induced by an externally applied magnetic field. It could be shown experimentally that magnetic fields could assist laser surface treatment processes beneficially if higher beam powers were coupled in. This may be interesting if, for instance, thicker dispersed layers should be achieved

Material development for laser sintering of high temperature strength silicon carbide with extrem hardness

Laser sintering is described as an efficient and successful technique for the fast and direct production of complex-shaped prototypes of technical ceramics. After presentation of the state of the art of laser sintered silicon infiltrated silicon carbide (SiSiC) the paper describes new aspects of material development. Finer raw SiC powders were used and an additional carbon dotation process was established. The significantly higher SiC/Si phase ratio in the ceramic material results in increasing the 4-point flexural strength from 196 to 267 Mpa. Laser sintering of metal powder has been used in industry for direct production of injection molding tools, models and prototypes for several years. Produced parts are distinguished by accurate dimensions and contous and can have extremely complex and filigree geometries. Undercuts and holes can be generated in the part very simply because layers are built up to produce the end part. The potential for application of laser sintered SiSiC is given by the possibility to realize prototypes very fast and efficiently as well as by the possibility to create free shaped and filigree geometries. The aim of the presented work was the improvement of the mechanical properties of laser sintered SiSiC, especially a significant improvement of their flexural strength was intended. The lower flexural strength of laser sintered SiSiC in comparison to material made conventionally by powder technology can be explained by the relatively high content of silicon in the laser sinterered material. Two silicon carbide powders with average grain sizes of 13 and 23 micrometer were used. A surprisingly wide variety of solidification mechanisms were found. Sintered agglomerates typical for metal laser sintering were rarely found

Lasersintern von technischer Keramik

Laser sintering is described as an efficient and successful technique for the fast and direct production of complex-shaped prototypes of technical ceramics. After presentation of the state of the art of laser sintered silicon infiltered silicon carbide (SiSiC) the paper describes new aspects of material development. Finer raw SiC powders are used and an additional carbon dotation process is established. The significantly higher SiC/Si phase ratio in the ceramic material results in increasing the 4-point flexural strength from 196 to 267 MPa

Natural hazard fatalities in Switzerland from 1946 to 2015

A database of fatalities caused by natural hazard processes in Switzerland was compiled for the period between 1946 and 2015. Using information from the Swiss flood and landslide damage database and the Swiss destructive avalanche database, the data set was extended back in time and more hazard processes were added by conducting an in-depth search of newspaper reports. The new database now covers all natural hazards common in Switzerland, categorised into seven process types: flood, landslide, rockfall, lightning, windstorm, avalanche and other processes (e.g. ice avalanches, earthquakes). Included were all fatal accidents associated with natural hazard processes in which victims did not expose themselves to an important danger on purpose. The database contains information on 635 natural hazard events causing 1023 fatalities, which corresponds to a mean of 14.6 victims per year. The most common causes of death were snow avalanches (37 %), followed by lightning (16 %), floods (12 %), windstorms (10 %), rockfall (8 %), landslides (7 %) and other processes (9 %). About 50 % of all victims died in one of the 507 single-fatality events; the other half were killed in the 128 multi-fatality events. <br><br> The number of natural hazard fatalities that occurred annually during our 70-year study period ranged from 2 to 112 and exhibited a distinct decrease over time. While the number of victims in the first three decades (until 1975) ranged from 191 to 269 per decade, it ranged from 47 to 109 in the four following decades. This overall decrease was mainly driven by a considerable decline in the number of avalanche and lightning fatalities. About 75 % of victims were males in all natural hazard events considered together, and this ratio was roughly maintained in all individual process categories except landslides (lower) and other processes (higher). The ratio of male to female victims was most likely to be balanced when deaths occurred at home (in or near a building), a situation that mainly occurred in association with landslides and avalanches. The average age of victims of natural hazards was 35.9 years and, accordingly, the age groups with the largest number of victims were the 20–29 and 30–39 year-old groups, which in combination represented 34 % of all fatalities. It appears that the overall natural hazard mortality rate in Switzerland over the past 70 years has been relatively low in comparison to rates in other countries or rates of other types of fatal accidents in Switzerland. However, a large variability in mortality rates was observed within the country with considerably higher rates in Alpine environments