Temporal structural changes of protoplanetary disks surrounding T Tauri stars (TTSs) can cause magnitude variations of TTSs. On the other hand, variability is also expected due to cool spots and/or hot spots on the surface of the star, thus it is important to distinguish the causes of the observed variability. Our sample consists of 23 TTSs (22 classical T Tauri stars, 1 weak-lined T Tauri star) and 4 Herbig Ae/Be stars. The observations were performed over a period of about 3 months in the V, J, and KS band, simultaneously. We detected variability for all stars in the three bands (>0.05 mag in V, >0.09 mag in J, >0.09 mag in KS). Color-magnitude relations obtained between V, J, and KS bands suggest that stellar spots are not the only cause of variability for most of our targets. In addition, the data implies that six stellar systems contain larger grains than in the interstellar medium if the variability is only caused by extinction due to circumstellar matter.

Engineering and manufacturing of thick and bio-functional tissue products is one of the big issues in tissue engineering. To produce such tissues, we need some innovative technologies, which enable us to build up thick, three-dimensional structures and to arrange multiple types of cells to make complicated tissue structures. Based on such considerations, we have developed a custom-made inkjet 3D bioprinter, which realized both of direct cell printing and 3D laminating printing with cells and hydrogel. Recently, it has been improved, and here we report recent progresses and our achievements with new version 3D bioprinter.

Image based printing mode and active Z-axis control system were added. As a useful structure, an image of multi-honeycomb pattern was designed in computer and next it was copied and finally in total 100 image data were prepared. Using those digital data, 3D image of thick multi-honeycomb structure was reconstructed in computer, and then, laminating printing was carried out using our new version 3D bioprinter with alginate hydrogel. The new version printer showed good performance of 3D laminating printing and finally complicated 3D multi-honeycomb hydrogel structures could be successfully fabricated. It is indicated that fabrication of cell containing 3D structures based on the computer aided designs is feasible and that such biofabrication technologies must contribute to further innovative advancement of tissue engineering.