Influence of process parameters on part quality and mechanical properties for DMLS and SLM with iron-based materials

Rapid manufacturing is an advanced manufacturing technology based on layer-by-layer manufacturing to produce a part. This paper presents experimental work carried out to investigate the effects of scan speed, layer thickness, and building direction on the following part features: dimensional error, surface roughness, and mechanical properties for DMLS with DS H20 powder and SLM with CL 20 powder (1.4404/AISI 316L). Findings were evaluated using ANOVA analysis. According to the experimental results, build direction has a significant effect on part quality, in terms of dimensional error and surface roughness. For the SLM process, the build direction has no influence on mechanical properties. Results of this research support industry estimating part quality and mechanical properties before the production of parts with additive manufacturing, using iron-based powders

Application of metabolic engineering to the production of scopolamine

Scopolamine is an alkaloid widely used in medicine for its anticholinergic activity. The aim of this review is to show that metabolic engineering techniques constitute a suitable tool to improve the production of tropane alkaloids, focusing in particular on scopolamine. We present an overview of results obtained by various research groups, including our own, who have studied the overexpression of genes involved in the biosynthesis of scopolamine in different plant species that produce tropane alkaloids. Experiments carried out to improve production in hairy root cultures will also be described, as well as those attempting to biotransform hyoscyamine into scopolamine in roots and transgenic tobacco cells.

Biotechnological production of taxanes: a molecular approach

Plant cell cultures constitute a promise for the production of a high number of phytochemicals, although the majority ofbioprocesses that have been developed so far have not resultedcommercially successful. An overview indicates that most of theresearch carried out until now is of the empirical type. For this reason,there is a need for a rational approach to the molecular and cellularbasis of metabolic pathways and their regulation in order to stimulatefuture advances.The empirical investigations are based on the optimization of theculture system, exclusively considering input factors such as theselection of cellular lines, type and parameters of culture, bioreactordesign and elicitor addition, and output factors such as cellular growth,the uptake system of nutrients, production and yield. In a rationalapproach towards the elucidation of taxol and related taxaneproduction, our group has studied the relationship between the taxaneprofile and production and the expression of genes codifying forenzymes that participate in early, intermediate and late steps of theirbiosynthesis in elicited Taxus spp cell cultures. Our results show that elicitors induce a dramatic reprogramming of gene expression in Taxus cell cultures, whichlikely accounts for the enhanced production of taxol and related taxanes and we have alsodetermined some genes that control the main flux limiting steps. The application ofmetabolic engineering techniques for the production of taxol and taxanes of interest is also discussed.