Arts et Métiers ParisTech

About: Arts et Métiers ParisTech is a education organization based out in Paris, France. It is known for research contribution in the topics: Finite element method & Machining. The organization has 3946 authors who have published 6693 publications receiving 142083 citations. The organization is also known as: École nationale supérieure d'arts et métiers & ENSAM.

Identification of a triacylglycerol lipase gene family in Candida deformans: molecular cloning and functional expression.

Abstract: The yeast Candida deformans CBS 2071 produces an extracellular lipase which was shown to catalyse the production of various esters by the esterification of free fatty acids, even in the presence of a large molar excess of water. To clone the gene encoding this extracellular lipase, Saccharomyces cerevisiae was transformed with C. deformans genomic libraries and screened for lipolytic activity on a medium containing rapeseed oil emulsion and rhodamine B. Three members of a lipase gene family (CdLIP1, CdLIP2 and CdLIP3) were cloned and characterized. Each deduced lipase sequence has a Gly-His-Ser-Leu-Gly-(Gly/Ala)-Ala conserved motif, eight cysteine residues and encodes an N-terminal signal sequence. MALDI-TOF mass spectrometry analysis of a proteolytic digest of the lipase produced was used to obtain experimental evidence that the CdLIP1 gene encoded the extracellular lipase. Recombinant expression studies confirmed that the cloned genes encoded functional lipases. The three lipases are very similar to lipases from the related species Yarrowia lipolytica. Significant homologies were also found with several yeast and fungal lipases. As C. deformans CBS 2071 was previously considered to be synonymous with Y. lipolytica, the strains were compared for the extent of nucleotide divergence in the variable regions (D1/D2) at the 5'-end of the large-subunit (26S) ribosomal DNA (rDNA) gene. This rDNA region has diverged sufficiently to suggest that C. deformans is a separate species. The nucleotide sequences of the CdLIP1, CdLIP2 and CdLIP3 genes will appear in the EMBL nucleotide sequence database under Accession Nos AJ428393, AJ428394 and AJ428395, respectively.

Correlation of crystallization behavior and mechanical properties of thermal sprayed PEEK coating

Abstract: An amorphous PEEK coating was prepared on an Al substrate by a flame spraying process. The amorphous coating was subjected to an annealing treatment under an annealing temperature from 180 to 300 °C and a holding time from 1 to 30 min. The cold crystallization behavior of the as-sprayed coating differential scanning calorimetry (DSC) and wide angle X-ray diffraction (WAXD) measurements. The hardness and tribological behavior of the coatings were investigated. Both DSC and WAXD analysis revealed that the annealed coatings exhibited a semi-crystalline structure. Coexistence of double crystal entities in annealed coatings was deduced. The annealed coatings exhibit higher hardness, lower friction coefficient and wear rate. Both the annealing temperature and holding time can benefit the coating hardness. The annealing condition in the studied range has little influence on the tribological behavior of the coatings. The variances of the coating mechanical properties were correlated with the modifications of the coating structures induced by the annealing treatments.