ABSTRACT
Pristine high-density bulk disks of MgB2 with added hexagonal BN (10 wt.%) were prepared using spark plasma sintering. The BN-added samples are machinable by chipping them into desired geometries. Complex shapes of different sizes can also be obtained by the 3D printing of polylactic acid filaments embedded with MgB2 powder particles (10 wt.%). Our present work aims to assess antimicrobial activity quantified as viable cells (CFU/mL) vs. time of sintered and 3D-printed materials. In vitro antimicrobial tests were performed against the bacterial strains Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, Staphylococcus aureus ATCC 25923, Enterococcus faecium DSM 13590, and Enterococcus faecalis ATCC 29212; and the yeast strain Candida parapsilosis ATCC 22019. The antimicrobial effects were found to depend on the tested samples and microbes, with E. faecium being the most resistant and E. coli the most susceptible.
Subject(s)
Anti-Infective Agents/pharmacology , Bacteria/drug effects , Boron Compounds/pharmacology , Fungi/drug effects , Magnesium Compounds/pharmacology , Candida parapsilosis/drug effects , Enterococcus faecalis/drug effects , Enterococcus faecium/drug effects , Escherichia coli/drug effects , Microbial Sensitivity Tests , Polyesters/pharmacology , Printing, Three-Dimensional , Pseudomonas aeruginosa/drug effects , Staphylococcus aureus/drug effectsABSTRACT
We report for the first time on the antimicrobial activity of MgB2 powders produced via the Reactive Liquid Infiltration (RLI) process. Samples with MgB2 wt.% ranging from 2% to 99% were obtained and characterized, observing different levels of grain aggregation and of impurity phases. Their antimicrobial activity was tested against Staphylococcus aureus ATCC BAA 1026, Enterococcus faecalis ATCC 29212, Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, and Candida albicans ATCC 10231. A general correlation is observed between the antibacterial activity and the MgB2 wt.%, but the sample microstructure also appears to be very important. RLI-MgB2 powders show better performances compared to commercial powders against microbial strains in the planktonic form, and their activity against biofilms is also very similar.
ABSTRACT
Several studies have shown a tight connection between several ocular pathologies and an increased risk of hip fractures due to falling, especially among elderly patients. The total replacement of the hip joint is a major surgical intervention that aims to restore the function of the affected hip by various factors, such as arthritis, injures, and others. A corkscrew-like femoral stem was designed in order to preserve the bone stock and to prevent the occurrence of iatrogenic fractures during the hammering of the implant. In this paper, the finite element analysis for the proposed design was applied, considering different loads and three types of materials. A finite element analysis is a powerful tool to simulate, optimize, design, and select suitable materials for new medical implants. The results showed that the best scenario was for Ti6Al4V alloy, although Ti and 316L stainless steel had a reasonable high safety factor.
Subject(s)
Arthroplasty, Replacement, Hip/instrumentation , Hip Prosthesis , Prosthesis Design , Titanium , Alloys , Biomechanical Phenomena , Femur , Finite Element Analysis , Hip Fractures/surgery , Humans , Stress, MechanicalABSTRACT
Contact lenses are an attractive alternative for vision corrections. Their improvement can be achieved by optimizing the geometry, use of new materials, and application of high precision processing technologies. The optimized design can be obtained by computer-aided design, considering the principles of geometrical optics. Inventor Professional and other similar advanced 3D CAD software allows complex approaches, selection of suitable materials with better mechanical/ optical properties. This is useful for the preparation of the virtual design for 3D printing or CNC fabrication. A finite element analysis is also of interest for testing the best design/ material choice. In this paper, the finite element analysis for a tri-curve contact lens was applied. The selected materials were PMMA and polycarbonate. The applied compressive loads were in the range from 10 to 100MPa. Our results showed that the best scenario was for the polycarbonate, but PMMA also had a high safety factor. The maximum compression load with a reasonable safety factor (of 7-9 depending on materials) was 12MPa.
