Sirindhorn International Institute of Technology

About: Sirindhorn International Institute of Technology is a based out in . It is known for research contribution in the topics: Supply chain & Combustion. The organization has 1048 authors who have published 1678 publications receiving 30067 citations.

Maintenance of human chondrogenic phenotype on a dendrimer-immobilized surface for an application of cell sheet engineering.

Abstract: Dedifferentiation of chondrocytes during cell expansion is one of the barriers in tissue construction for cartilage repair. To understand chondrocyte behavior and improve cell expansion in monolayer culture, this study investigated the effects of morphological changes and cellular aggregation on the maintenance of chondrogenic capacity by observing the expression patterns of chondrogenic (collagen type II and aggrecan) and dedifferentiation (collagen type I) markers. Primary human chondrocytes were cultured on either a polystyrene surface (PS) or a polyamidoamine dendrimer surface with a fifth-generation (G5) dendron structure to create a one-step process of cell expansion and the maintenance of chondrogenic activities prior to the construction of cell sheets. During the first two passages (P0 - P2), the relative mRNA level of collagen type II decreased in all cultures, while that of collagen type I increased. Remarkably, the level of collagen type II was higher and aggrecan was retained in the chondrocytes, forming cell aggregates and showing some round-shaped cells with less production of stress fibers on the G5 surface compared to fibroblast-like chondrocytes with abundant stress fibers on the PS surface. The numbers of P2 chondrocytes on the G5 and PS surfaces were nearly the same and sufficient for construction of chondrocyte sheets using a temperature-responsive plate. Without a supporting material during cell sheet manipulation, chondrocyte sheets spontaneously detached and exhibited a honeycomb-like structure of stress fibers. Unlike the chondrocyte sheets constructed from cells on the PS surface, the chondrocyte sheets from cells on the G5 surface had higher chondrogenic activities, as evidenced by the high expression of chondrogenic markers and the low expression of dedifferentiation markers. The one-step process of cell expansion and maintenance of chondrogenic activity could be obtained using the G5 surface. Human chondrocyte sheets were successfully constructed with high chondrogenic activity. These findings may lead to an alternative cultivation technique for human chondrocytes that offers high clinical potential in autologous chondrocyte implantation.

A ground-structure-based representation with an element-removal algorithm for truss topology optimization

Abstract: In this study, a new ground-structure-based representation for truss topology optimization is proposed. The proposed representation employs an algorithm that removes unwanted elements from trusses to obtain the final trusses. These unwanted elements include kinematically unstable elements and useless zero-force elements. Since the element-removal algorithm is used in the translation of representation codes into corresponding trusses, this results in more representation codes in the search space that are mapped into kinematically stable and efficient trusses. Since more representation codes in the search space represent stable and efficient trusses, the strategy increases meaningful competition among representation codes. This remapping strategy alleviates the problem of having large search spaces using ground structures, and encourages faster convergences. To test the effectiveness of the proposed representation, it is used with a simple multi-population particle swarm optimization algorithm to solve several truss topology optimization problems. It is found that the proposed representation can significantly improve the performance of the optimization process.

Pretreatment evaluation and its application on palm oil mill effluent for bio-hydrogen enhancement and methanogenic activity repression.

Abstract: Pretreatment evaluations of biological sludge were performed to observe the enhancement of hydrogen production and repression of methanogenic activity using anaerobic sludge and sucrose as substrate. The treatments include heating (H), ozonation (O), drug (D) application using fluvastatin, Na2SO4(S) dosing and their combinations to make up for the total of 9 pretreatment methods. Heat treatment at 95 degrees C for 45 min provided a complete methanogen repression and good enhancement of hydrogen production activity. The remaining pretreatments were imperfect either for repression or enhancement based on the application conditions and concentration ranges. The order of methane repression was: H > HO > HD > HS > O > D > OD > OS > S while hydrogen production was: HO > H > HS > OD > HD > OS > D > O > S. Heat treatment at the specified condition was considered sufficient and suitable for pretreatment of anaerobic sludge. The practical application was explored using Palm Oil Mill Effluent (POME) containing different amounts of solid content (15.830 g VSS L(-1), namely LPOME and 21.445 g VSS L(-1), namely HPOME) as substrate. Beside the difference in COD of nearly 16% which is higher for HPOME, a higher specific hydrogen production rate was obtained at 0.81 and 0.17 mL H2g (-1) COD h for LPOME and HPOME, respectively. It should also be noted that a prolonged lag-time during start-up was observed for HPOME as well as hydrogen suppression which may be associated with the solid content mainly lipids in wastewater. Thus, high solid content of wastewater may be of concerned for bio-hydrogen production.