October 24, 2019 by admin 0 Comments

3D Printing of Zeolite for Adsorption of Radioisotopes from a Nuclear Reactor Coolant

Authors
Sujeong Lee (a), Ho Jin Ryu (a, *)
Abstract
In operating nuclear power plants, the radionuclides are present in the reactor coolant system. These radionuclides are generated primarily by activation of dissolved ions released from structural components into the coolant. These isotopes should be removed for treating liquid wastes in aspect of safety and economically. There are many studies on the adsorption of dissolved Co (Ⅱ) and Ni (Ⅱ) ions by inorganic adsorbents (e.g. molecular sieve, kaolinite clay). Treatment of the liquid wastes with the inorganic adsorbent is preferred because of its high exchange capacity, possible selectivity and specificity, good resistant to radiation. Manufacturing of ceramic filters is difficult because of brittleness of ceramics. Furthermore, fabrication cost for ceramics is five times higher than fabricating of polymers. Thus, ceramic 3D printing based on extrusion of slurry ink has an advantage in making a filter of adsorbents, because 3D printing can reduce processing time and cost to form a complex filter structure.

May 3, 2019 by admin 0 Comments

Analytical study on the 3D-printed structure and mechanical properties of basalt fiber-reinforced PLA composites using X-ray microscopy

Authors
Siwon Yu (a, b), Yun Hyeong Hwang (b), Jun Yeon Hwang (b), Soon Hyung Hong (a)
Abstract
A high-resolution X-ray microscope was used to quantitate the internal morphological characteristics of 3D-printed, basalt-fiber-reinforced PLA composites. 3D-printed composites have microstructures and mechanical properties that are distinct from those of conventional mold-pressed composites. One such distinction lies in the presence of voids, which form naturally during 3D printing. All of the composite components, including the fiber, the matrix, and the aforementioned voids were oriented parallel to the printing direction. The mechanical properties of the final composites were also greatly impacted by their microstructural characteristics, including fiber length, fiber orientation, and the presence of voids. It was also confirmed that the voids generated during the 3D printing process can be classified into two types (inter- and inner-filament voids), whose shapes, sizes, and distributions are completely different from each other, and that they clearly have a decisive influence on the remarkable differences in the strength of the composites.

December 13, 2018 by admin 0 Comments

Three‐dimensional‐printed vaginal applicators for electronic brachytherapy of endometrial cancers

Authors
Ju Hyuk Lee, Hyun Nam Kim, Hyung San Lim, Sung Oh Cho
Abstract
Purpose Vaginal applicators for a novel miniature x‐ray tube were developed using three‐dimensional (3D) printing to be used in brachytherapy of endometrial cancers. Methods Cylindrical vaginal applicators with various diameters, lengths, and infill percentages (IFPs) were fabricated using a 3D printer. X‐ray dose distributions and depth‐dose profiles were calculated using a Monte Carlo simulation. The performances of the applicators were evaluated by measuring and analyzing the dosimetric characteristics of x rays generated from the miniature x‐ray tube equipped with the applicators. Results Quite uniform dose distributions around the applicators were achieved by optimizing the dwell positions and the dwell times of the miniature x‐ray tube inside the applicators. In addition, identical absolute dose and depth‐dose profiles were obtained through the control of the IFP values even though different‐sized applicators are used. Conclusion The presented 3D printing technique provides an efficient approach to provide vaginal applicators with optimal IFPs that allow consistent treatment time for patients of varying vaginal canal size.

November 2, 2015 by admin 0 Comments

A novel electroporation system for efficient molecular delivery into Chlamydomonas reinhardtii with a 3-dimensional microelectrode

Authors
Seongsu Kang, Kwon-Ho Kim & Yeu-Chun Kim
Abstract
Electroporation is one of the most widely used transfection methods because of its high efficiency and convenience among the various transfection methods. Previous micro-electroporation systems have some drawbacks such as limitations in height and design, time-consuming and an expensive fabrication process due to technical constraints. This study fabricates a three dimensional microelectrode using the 3D printing technique. The interdigitated microstructure consisting of poly lactic acid was injected by a 3D printer and coated with silver and aluminum with a series of dip-coatings. With the same strength of electric field (V cm−1), a higher efficiency for molecular delivery and a higher cellular viability are achieved with the microelectrode than with a standard cuvette. In addition, this study investigates chemicophysical changes such as Joule heating and dissolved metal during electroporation and showed the micro-electroporation system had less chemicophysical changes. It was concluded that the proposed micro-electroporation system will contribute to genetic engineering as a promising delivery tool and this combination of 3D printing and electroporation has many potential applications for diverse designs or systems.