Repair of automotive bumpers and bars with modified friction stir welding

This study reports the investigations for repair of thermoplastic based automotive bumpers and bars with modified friction stir welding(MFSW)process.For MFSW,consumable tool of polyamide6(PA6)composite has been used for joining of acrylonitrile butadiene styrene(ABS)composites.The dissimilar thermoplastics were processed for maintaining a useful range of melt flow properties followed by preparation of feed stock filament for fused deposition modeling(FDM)process through screw extrusion.Finally,3D printed PA6 based consumable rapid tool(RT)was prepared for MFSW.The joints prepared were subjected to flexural,hardness,morphological and thermal testing.The study has suggested the that maximum mechanical strength was obtained for sample welded at 1400 r/min,50 mm/min transverse speed and 3 mm plunge depth,whereas the minimum mechanical strength was obtained for sample welded at 1000 r/min,30 mm/min transverse speed and 2 mm plunge depth.The results are also supported with thermal analysis and photomicrographs.

Comparison of wear behavior of ABS and Nylon6-Fe powder composite parts prepared with fused deposition modelling

Fused deposition modeling(FDM) is one of the latest rapid prototyping techniques in which parts can be manufactured at a fast pace and are manufactured with a high accuracy. This research work is carried out to study the friction and wear behavior of parts made of newly developed Nylon6-Fe composite material by FDM. This work also involves the comparison of the friction and wear characteristics of the Nylon6-Fe composite with the existing acrylonitrile butadiene styrene(ABS) filament of the FDM machine. This Is carried out on the pin on disk setup by varying the load(5, 10, 15 and 20 N) and speed(200 and 300 r/min). It is concluded that the newly developed composite is highly wear resistant and can be used in industrial applications where wear resistance is of paramount importance. Morphology of the surface in contact with the Nylon6-Fe composite and ABS is also carried out.

Rheological,mechanical,thermal,tribological and morphological properties of PLA-PEKK-HAp-CS composite

The present study reports investigations on rheological,mechanical,thermal,tribological and morphological properties of feedstock filaments prepared with polylactic acid-polyether ketone ketone-hydroxyapatite-chitosan(PLA-PEKK-HAp-CS)composite for 3D printing of functional prototypes.The study consists of a series of melt processing operations on melt flow index(MFI)setup as per ASTM D-1238 for melt flow certainty followed by fixation of reinforcement composition/proportion as 94%PEKK-4%HAp-2%CS(B)by mass in PLA matrix(A).The blending of reinforcement and preparation of feedstock filament for fused deposition modeling(FDM)set up has been performed on commercial twin screw extruder(TSE).The results of study suggest that feedstock filaments prepared with blend of 95%A-5%B(by mass)at 200℃processing temperature and 100 r/min rotational speed on TSE resulted into better tensile properties(35.9 MPa peak strength and 32.3 MPa break strength)with 6.24%surface porosity,42.67 nm surface roughness(R_(a))and acceptable heat capacity(2.14 J/g).However as regards to tribological behavior,the minimum wear of 316μm was observed for sample with poor tensile properties.As regards to crash application for scaffolds the maximum toughness of 1.16 MPa was observed for 85%A-15%B(by mass)at 200℃processing temperature and 150 r/min rotational speed on TSE.

Ecdysis triggering hormone peptide in the African malaria mosquito Anopheles gambiae:The peptide structure for receptor activation

Infections by mosquito-borne diseases represent one of the leading causes of death in third world countries.The rapid progression of resistance to conventional insecticide causes a significant threat to the highly efficient preventive methods currently in place.Insect neuropeptidergic system offers potential targets to control the insect vectors.The essential roles of the neuropeptide ecdysis triggering hormone(ETH)in insect development and reproduction led us to attempt understanding of the fundamentals of the biochemical interaction between ETH and its receptor in the African malaria mosquito Anopheles gambiae.One of two ETH peptides of the African malaria mosquito(AgETH1),a small peptide hormone with 17 amino acid residues(SESPGFFIKLSKSVPRI-NH2),was studied to elucidate its molecular structure.N-termini deletions and mutations of conserved amino acids in the ligand revealed the critical residues for the receptor activation.The solution structure of AgETH1 using 2D 1H-1H nuclear magnetic resonance(NMR)spectroscopy and nuclear overhauser effect(NOE)derived constraints revealed a short alpha helix between residues 3S and 11S.The NMR solution structure of AgETH1 will be of significant assistance for designing a new class of insecticidal compounds that acts on the AgETH receptor aiming for in silico docking studies.