Effects of binder on suction in cemented gangue backfill
MAGAZINE OF CONCRETE RESEARCH
Authors: Wu, Di; Cai, Si-jing; Liu, Yu-cheng
Abstract
Cemented gangue backfill (CGB, a mixture of coal gangue, cement and water) is widely used in China for backfilling in coal mines. The addition of fly ash to CGB mixtures can help them to have favourable environmental and economic performance. In addition, mechanical stability and durability are also important performance criteria for CGB, and these two criteria are closely related to the suction of CGB. The evolution of suction in CGB is influenced by binder hydration, which is an exothermic process affecting the variation in temperature of CGB. To examine the coupled effects of binder hydration and temperature (including the temperatures of a CGB mixture and its surroundings), in this study a numerical model was developed to predict the development of suction in a CGB mixture containing fly ash. Data from a laboratory study were used to validate the developed model, and it was found that the results of the model simulation and the experimental study were in good agreement. Therefore, the proposed model was applied to simulate and determine the development of suction within the CGB mixture over curing time. The results obtained can contribute to better design and preparation of CGB mixtures, as well as better prediction of the evolution of suction within CGB structures.
Efficient production of trophoblast lineage cells from human induced pluripotent stem cells
LABORATORY INVESTIGATION
Authors: Kojima, Junya; Fukuda, Atsushi; Taira, Hayato; Kawasaki, Tomoyuki; Ito, Hiroe; Kuji, Naoaki; Isaka, Keiichi; Umezawa, Akihiro; Akutsu, Hidenori
Abstract
Human induced pluripotent stem cells (hiPSCs) are potentially useful in both clinical applications and basic biological research. hiPSCs can differentiate into extra-embryonic cells in the presence of BMP4. However, the differentiation potential of hiPSCs can be affected by culture conditions or genetic variation. In this study, we investigated the effect of various BMP4 concentrations on the expression states of trophoblast markers and the optimal conditions for trophoblast induction. A high-fidelity gene expression assay using hiPSC lines showed that the expression levels of various trophoblast marker genes, such as KRT7, GCM1, CGB, and HLA-G, were upregulated by BMP4 in a dose-dependent manner in all types of hiPSCs used in this study. Treatment with high doses of BMP4 for prolonged periods increased the ratio of cells with trophoblast markers irrespective of the presence of bFGF. We found that the expression states of major pluripotency- and differentiation-related protein-coding genes in BMP4-treated cells depended on culture conditions rather than donor cell types. However, miRNA expression states were affected by donor cell types rather than BMP4 dose. Furthermore, the effect of the presence of bFGF on differentiation potential of KRT7-positive cells differed among iPSC types. Mechanistically, chromatin states around KRT7 promoter regions were comparable among the iPSC types used in this study, indicating that hiPSC chromatin state at these regions is not a parameter for cytotrophoblast differentiation potential. In conclusion, the optimal conditions for trophoblast differentiation from hiPSCs differ according to parental cell line.