ABSTRACT
This study aims to assess whether ultra-high-molecular-weight polyethylene (UHMWPE) fibers can be successfully embedded in a polylactic acid (PLA) matrix in a material extrusion 3D printing (ME3DP) process, despite the apparent thermal incompatibility between the two materials. The work started with assessing the maximum PLA extrusion temperatures at which UHMWPE fibers withstand the 3D printing process without melting or severe degradation. After testing various fiber orientations and extrusion temperatures, it has been found that the maximum extrusion temperature depends on fiber orientation relative to extrusion pathing and varies between 175 °C and 185 °C at an ambient temperature of 25 °C. Multiple specimens with embedded strands of UHMWPE fibers have been 3D printed and following tensile strength tests on the fabricated specimens, it has been found that adding even a small number of fiber strands laid in the same direction as the load increased tensile strength by 12% to 23% depending on the raster angle, even when taking into account the decrease in tensile strength due to reduced performance of the PLA substrate caused by lower extrusion temperatures.
ABSTRACT
The following study reports on the first thraustochytrid isolates identified from Iceland. They were collected from three different locations off the northern coast of the country (Location A, Skagaströnd; Location B, Hveravík; and Location C, Eyjafjörður). Using 18S rDNA sequence analysis, isolates from Locations A and B were identified within the Thraustochytrium kinnei species while other isolates within the Sicyoidochytrium minutum species when compared to other known strains. Cells isolated from Locations A ( 2 . 10 ± 0 . 70 g/L) and B ( 1 . 54 ± 0 . 17 g/L) produced more biomass than the ones isolated from Location C ( 0 . 43 ± 0 . 02 g/L). This study offers the first-time examination of the utility of byproducts from fisheries as a nitrogen source in media formulation for thraustochytrids. Experiments showed that isolates produced more biomass (per unit of substrate) when cultured on nitrogen of marine ( 2 . 55 ± 0 . 74 g/L) as compared to of commercial origin ( 1 . 06 ± 0 . 57 g/L). Glycerol ( 2 . 43 ± 0 . 56 g/L) was a better carbon source than glucose ( 1 . 84 ± 0 . 57 g/L) in growth studies. Fatty acid (FA) profiles showed that the isolates from Location C (S. minutum) had low ratios of monounsaturated ( 4 . 21 ± 2 . 96 % ) and omega-6 ( 0 . 68 ± 0 . 59 % ) FAs. However, the isolates also had high ratios of docosahexaenoic acid (DHA; 35 . 65 ± 1 . 73 % ) and total omega-3 FAs ( 40 . 39 ± 2 . 39 % ), indicating that they could serve as a source of marine oils for human consumption and in aquaculture feeds. The T. kinnei isolates from Location A could be used in biodiesel production due to their high ratios of monounsaturated ( 18 . 38 ± 6 . 27 % ) long chain ( 57 . 43 ± 8 . 27 % ) FAs.
Subject(s)
Aquatic Organisms/metabolism , Biofuels , Industrial Microbiology/methods , Stramenopiles/metabolism , Aquatic Organisms/isolation & purification , Cell Culture Techniques/methods , Culture Media/chemistry , Fatty Acids, Omega-3/isolation & purification , Fatty Acids, Omega-3/metabolism , Fatty Acids, Omega-6/isolation & purification , Fatty Acids, Omega-6/metabolism , Fisheries , Glycerol/chemistry , Iceland , Nitrogen/chemistry , Stramenopiles/isolation & purificationABSTRACT
Marine sponges and other sessile macro-organisms were collected at a shallow water hydrothermal site in Eyjafjörður, Iceland. Bacteria were isolated from the organisms using selective media for actinomycetes, and the isolates were screened for antimicrobial activity. A total of 111 isolates revealed antimicrobial activity displaying different antimicrobial patterns which indicates production of various compounds. Known test strains were grown in the presence of ethyl acetate extracts from one selected isolate, and a clear growth inhibition of Staphylococcus aureus was observed down to 0.1 % extract concentration in the medium. Identification of isolates shows different species of Actinobacteria with Streptomyces sp. playing the largest role, but also members of Bacilli, Alphaproteobacteria and Gammaproteobacteria. Sponges have an excellent record regarding production of bioactive compounds, often involving microbial symbionts. At the hydrothermal vents, however, the majority of active isolates originated from other invertebrates such as sea anemones or algae. The results indicate that antimicrobial assays involving isolates in full growth can detect activity not visible by other methods. The macro-organisms inhabiting the Eyjafjörður hydrothermal vent area host diverse microbial species in the phylum Actinobacteria with antimicrobial activity, and the compounds responsible for the activity will be subject to further research.
