THE ROTATIONAL EFFECT OF MAGNETIC PARTICLES ON CELLULAR APOPTOSIS BASED ON FOUR ELECTROMAGNET FEEDBACK CONTROL SYSTEM

Objectives: Magnetic drug targeting offers the latest popular alternative option to deliver magnetic drug carriers into targeting region body parts through manipulation of an external magnetic field. However, the effectiveness of using an electromagnetic field to manipulate and directing magnetic particles is yet to be established. Methods: In this paper, a homemade cost-effective electromagnet system was built for the purpose of studying the control and directing the magnetic drug carriers. The electromagnet system was built with four electromagnetic sources and tested the capability in directing the particles’ movement in different geometry patterns. Besides that, the creation of the self-rotation of individual magnetic particle clusters was achieved by using fast switching between magnetic fields. This self-rotation allows the possibility of cell apoptosis study to carry out. The system was constructed with four electromagnets integrated with a feedback control system and built to manipulate a droplet of commercially available iron (II, III) oxide nanoparticles to steer the magnetic droplet along different arbitrary trajectories (square, circle, triangle, slanted line) in 2-dimensional. Results: A dynamic magnetic field of 25 Hz was induced for magnetic nanoparticles rotational effect to observe the cell apoptosis. A profound outcome shows that the declining cell viability of the cell lines by 40% and the morphology of shrinking cells after the exposure of the dynamic magnetic field. Conclusion: The outcome from the pilot study gives an idea on the laboratory setup serves as a fundamental model for studying the electromagnetic field strength in applying mechanical force to target and to rotate for apoptosis on cancer cell line study.

Improved Method for Fracture Toughness Testing Using Compliance Method for High Toughness Materials

In order to ensure the integrity of structures such as gas turbines and nuclear power plants, the materials used should have excellent toughness. Especially in the case of nuclear piping materials applied to leak before break (LBB) design, high toughness materials are used to meet the stringent fracture toughness criteria and integrity must be verified through static J-R curve testing using the compliance method, one of the measurement techniques for fracture toughness. The measured and estimated values for the crack extension length during the test should also match, within a certain tolerance. However, in the case of materials with high toughness, rotation of the specimen becomes significant, because the test is performed until the crack open displacement (COD) is relatively large to ensure sufficient crack extension. In this case, it is not easy to satisfy these conditions due to the rotational effect on the specimen. Even though ASTM E1820 suggests a method for correcting the crack length for the rotational effect on these specimens, it has been found that there are substantial differences for high toughness materials. To solve this problem, a new crack length correction formula considering the rotation effect is proposed. Through analysis of the data from J-R curve testing with this proposed method, it was confirmed that the accuracy of crack extension length estimation is improved compared to the existing method. The proposed method well explains the variation of crack extension length due to rotation and is suitable as a correction equation for rotation of compact tension specimens.