An investigation on moisture and water absorption in cement paste with electrical resistance method

Moisture in concrete is one of main factors related to degradation and deterioration of concrete structure, and there are various moisture transport phenomena in concrete such as drying and absorbing. There are a lot of previous studies on the drying process of concrete to clarify the mechanisms of creep as well as shrinkage. However, few studies have been reported on the process of water absorption and moisture absorption although carbonation and chloride attack are strongly related to moisture and water absorbing. It is necessary to investigate moisture transfer in concrete in detail. This study investigated the moisture transfer in moisture and water absorbing processes in cement paste by using electrical resistance method to understand how moisture and water transfer into concrete. Cement paste specimens with water-to-cement ratios (W/Cs) of 0.35 and 0.55 were prepared in this study. Stainless steel rods of 0.9 mm in diameter were arranged at an interval of 4 mm in the specimen for measuring the electrical resistance. The specimens for moisture and water absorbing test were cured in water at 20 ºC for 28 days and stored at 20 ºC and a relative humidity of 0% and 70% as reference and the national average of the annual average relative humidity in Japan, respectively. The electrical resistances were measured through the stainless-steel rods and converted to electrical resistivity. The calibration test was also conducted to obtain the relationship between the electrical resistivity and the internal relative humidity (IRH), which was used to know IRH in cement paste specimen. As a result, the rate of moisture transfer in the specimen at initial internal relative humidity (IIRH) of 0% was higher than that at IIRH of 70%. Additionally, the rate of moisture transfer in the specimen at any IIRH depends on the total pore volume in the specimen

Robust and highly efficient hiPSC generation from patient non-mobilized peripheral blood-derived CD34+ cells using the auto-erasable Sendai virus vector

Background: Disease modeling with patient-derived induced pluripotent stem cells (iPSCs) is a powerful tool forelucidating the mechanisms underlying disease pathogenesis and developing safe and effective treatments. Patientperipheral blood (PB) cells are used for iPSC generation in many cases since they can be collected with minimuminvasiveness. To derive iPSCs that lack immunoreceptor gene rearrangements, hematopoietic stem and progenitorcells (HSPCs) are often targeted as the reprogramming source. However, the current protocols generally requireHSPC mobilization and/or ex vivo expansion owing to their sparsity at the steady state and low reprogrammingefficiencies, making the overall procedure costly, laborious, and time-consuming.Methods: We have established a highly efficient method for generating iPSCs from non-mobilized PB-derivedCD34+ HSPCs. The source PB mononuclear cells were obtained from 1 healthy donor and 15 patients and werekept frozen until the scheduled iPSC generation. CD34+ HSPC enrichment was done using immunomagnetic beads,with no ex vivo expansion culture. To reprogram the CD34+-rich cells to pluripotency, the Sendai virus vectorSeVdp-302L was used to transfer four transcription factors: KLF4, OCT4, SOX2, and c-MYC. In this iPSC generationseries, the reprogramming efficiencies, success rates of iPSC line establishment, and progression time wererecorded. After generating the iPSC frozen stocks, the cell recovery and their residual transgenes, karyotypes, T cellreceptor gene rearrangement, pluripotency markers, and differentiation capability were examined.Results：We succeeded in establishing 223 iPSC lines with high reprogramming efficiencies from 15 patients with 8 different disease types. Our method allowed the rapid appearance of primary colonies (~ 8 days), all of which were expandable under feeder-free conditions, enabling robust establishment steps with less workload. After thawing, the established iPSC lines were verified to be pluripotency marker-positive and of non-T cell origin. A majority of the iPSC lines were confirmed to be transgene-free, with normal karyotypes. Their trilineage differentiation capability was also verified in a defined in vitro assay.Conclusion：This robust and highly efficient method enables the rapid and cost-effective establishment of transgene-free iPSC lines from a small volume of PB, thus facilitating the biobanking of patient-derived iPSCs and their use for the modeling of various diseases