Search

The antioxidant capacity and antioxidant constituents of two filamentous fungi (Acremonium charticola and Rhizopus oryzae) isolated from the Indonesian fermented dried cassava (gathot) were evaluated in the present study. The antioxidant capacity of the fungal crude extracts was assessed based on the 2,2′-azino-bis(3-ethyl-benzthiazolin-6-sulfonicacid) (ABTS) method. Total phenolics were determined based on the Folin-Ciocalteu method, while the flavonoids content in the fungal extracts was determined by the spectrophotometric method with aluminum chloride. Total tannins were estimated by the Folin-Denis method. The ABTS+ radical scavenging activity was higher (p < 0.01) in A. charticola compared to that in R. oryzae and ascorbic acid (as a control). A higher (p < 0.01) content of total phenolics was detected in A. charticola than that in R. oryzae. Total flavonoids were higher (p < 0.01) in R. oryzae as compared with that in A. charticola. The fungus A. charticola had a higher (p < 0.01) level of total tannins than R. oryzae. In conclusion, both filamentous fungi isolated from the Indonesian fermented dried cassava exhibited antioxidant potentials as indicated by their capabilities to scavenge ABTS+. A. charticola had a higher antioxidant capacity than R. oryzae. The antioxidant capacity of A. charticola was attributed mainly to its phenolics and tannins contents.

Due to polymeric wear debris causing osteolysis from polymer, metal ions causing metallosis from metal, and brittle characteristic causing fracture failure from ceramic in the application on bearing of total hip prosthesis requires the availability of new material options as a solution to these problems. Polycrystalline diamond (PCD) has the potential to become the selected material for hard-on-hard bearing in view of its advantages in terms of mechanical properties and biocompatibility. The present study contributes to confirming the potential of PCD to replace metals and ceramics for hard-on-hard bearing through von Mises stress investigations. A computational simulation using a 2D axisymmetric finite element model of hard-on-hard bearing under gait loading has been performed. The percentage of maximum von Mises stress to respective yield strength from PCD-on-PCD is the lowest at 2.47%, with CoCrMo (cobalt chromium molybdenum)-on-CoCrMo at 10.79%, and Al 2 O 3 (aluminium oxide)-on-Al 2 O 3 at 13.49%. This confirms that the use of PCD as a hard-on-hard bearing material is the safest option compared to the investigated metal and ceramic hard-on-hard bearings from the mechanical perspective.