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In this study, the amount of calcite precipitate resulting from microbially induced calcite precipitation (MICP) was estimated in order to determine the optimal conditions for precipitation. Two microbial species (Staphylococcus saprophyticus and Sporosarcina pasteurii) were tested by varying certain parameters such as (1) initial potential of hydrogen (pH) of urea-CaCl2 medium, (2) temperature during precipitation, and (3) the reaction duration. The pH values used for testing were 6, 7, 8, 9, and 10, the temperatures were 20, 30, 40, and 50 °C, and the reaction durations were 2, 3, and 4 days. Maximum calcite precipitation was observed at a pH of 7 and temperature of 30 °C. Most of the precipitation occurred within a reaction duration of 3 days. Under similar conditions, the amount of calcite precipitated by S. saprophyticus was estimated to be five times more than that by S. pasteurii. Both the species were sensitive to temperature; however, S. saprophyticus was less sensitive to pH and required a shorter reaction duration than S. pasteurii.

The simple yet powerful technique of induced pluripotency may eventually supply a wide range of differentiated cells for cell therapy and drug development. However, making the appropriate cells via induced pluripotent stem cells (iPSCs) requires reprogramming of somatic cells and subsequent redifferentiation. Given how arduous and lengthy this process can be, we sought to determine whether it might be possible to convert somatic cells into lineage-specific stem/progenitor cells of another germ layer in one step, bypassing the intermediate pluripotent stage. Here we show that transient induction of the four reprogramming factors (Oct4, Sox2, Klf4, and c-Myc) can efficiently transdifferentiate fibroblasts into functional neural stem/progenitor cells (NPCs) with appropriate signaling inputs. Compared with induced neurons (or iN cells, which are directly converted from fibroblasts), transdifferentiated NPCs have the distinct advantage of being expandable in vitro and retaining the ability to give rise to multiple neuronal subtypes and glial cells. Our results provide a unique paradigm for iPSC-factor-based reprogramming by demonstrating that it can be readily modified to serve as a general platform for transdifferentiation.

Human embryonic stem cells (hESCs) hold enormous promise for regenerative medicine. Typically, hESC-based applications would require their in vitro differentiation into a desirable homogenous cell population. A major challenge of the current hESC differentiation paradigm is the inability to effectively capture and, in the long-term, stably expand primitive lineage-specific stem/precursor cells that retain broad differentiation potential and, more importantly, developmental stage-specific differentiation propensity. Here, we report synergistic inhibition of glycogen synthase kinase 3 (GSK3), transforming growth factor β (TGF-β), and Notch signaling pathways by small molecules can efficiently convert monolayer cultured hESCs into homogenous primitive neuroepithelium within 1 wk under chemically defined condition. These primitive neuroepithelia can stably self-renew in the presence of leukemia inhibitory factor, GSK3 inhibitor (CHIR99021), and TGF-β receptor inhibitor (SB431542); retain high neurogenic potential and responsiveness to instructive neural patterning cues toward midbrain and hindbrain neuronal subtypes; and exhibit in vivo integration. Our work uniformly captures and maintains primitive neural stem cells from hESCs.

Human pluripotent stem cell (hPSC)-derived intestinal organoids (hIOs) form 3D structures organized into crypt and villus domains, making them an excellent in vitro model system for studying human intestinal development and disease. However, hPSC-derived hIOs still require in vivo maturation to fully recapitulate adult intestine, with the mechanism of maturation remaining elusive. Here, we show that the co-culture with human T lymphocytes induce the in vitro maturation of hIOs, and identify STAT3-activating interleukin-2 (IL-2) as the major factor inducing maturation. hIOs exposed to IL-2 closely mimic the adult intestinal epithelium and have comparable expression levels of mature intestinal markers, as well as increased intestine-specific functional activities. Even after in vivo engraftment, in vitro-matured hIOs retain their maturation status. The results of our study demonstrate that STAT3 signaling can induce the maturation of hIOs in vitro, thereby circumventing the need for animal models and in vivo maturation. Human pluripotent stem cell-derived intestinal organoids (hIOs) are a useful model with which to study intestinal development and disease, but they require in vivo maturation to resemble adult tissue. Here, the authors show that T lymphocyte-derived IL-2 induces hIO maturation in vitro through the activation of STAT3.

Preventing rebar corrosion in reinforced concrete (RC) structures has been actively researched worldwide. One of the most powerful solutions is the use of fiber-reinforced polymer (FRP) rebars. However, there are limitations in the mechanical design and construction of FRP rebars because their tensile characteristics are extremely different from those of conventional rebars and they have a different modulus of elasticity. FRP rebars are relatively cost-efficient when fabricated with glass fibers, but they are still costly compared to conventional rebars. Therefore, hybrid rebars fabricated by covering conventional rebars with glass FRP (GFRP) materials were developed in this study. GFRP hybrid rebars have increased durability in marine environments while maintaining the same mechanical properties as conventional rebars. As the difference in rebar diameter of the bonded area decreased, the tensile strength of the concrete increased. As a result, pull-out failure or tensile failure caused by the yielding of the rebars occurred in small-diameter rebars. The experimental results showed that the maximum load for the D13 deformed steel bar was 52.2 kN at a bond length of 50 mm and 76.1 kN at 100 mm, while for the D19 deformed steel bar, it was 65.3 kN at 50 mm and 103.7 kN at 100 mm. The bond properties of hybrid GFRB rebars were found to be lower than those of deformed steel bars. These properties were improved greatly by increasing the thickness of the GFRP materials on the surface of the deformed steel bars, highlighting a path toward high-performance, corrosion-resistant concrete.

Human pluripotent stem cell (hPSC)-derived organoids and cells have similar characteristics to human organs and tissues. Thus, in vitro human organoids and cells serve as a superior alternative to conventional cell lines and animal models in drug development and regenerative medicine. For a simple and reproducible analysis of the quality of organoids and cells to compensate for the shortcomings of existing experimental validation studies, a quantitative evaluation method should be developed. Here, using the GTEx database, we construct a quantitative calculation system to assess similarity to the human organs. To evaluate our system, we generate hPSC-derived organoids and cells, and detected organ similarity. To facilitate the access of our system by researchers, we develop a web-based user interface presenting similarity to the appropriate organs as percentages. Thus, this program could provide valuable information for the generation of high-quality organoids and cells and a strategy to guide proper lineage-oriented differentiation. Quantitative methods to assess the quality of hPSC-derived organoids have not been developed. Here they present a prediction algorithm to assess the transcriptomic similarity between hPSC-derived organoids and the corresponding human target organs and perform validation on lung bud organoids, antral gastric organoids, and cardiomyocytes.

In the construction of a twin-steel box-girder bridge, external cross-frames are temporarily used to increase torsional resistance. These members are regarded as secondary and are removed after a composite action in the bridge is achieved. Recently, attention has been paid to the possibility that external cross-frames can be a redundant source in bridges with girder fractures. In this study, the effects of external cross-frames on a damaged bridge were investigated using finite-element bridge models. Therefore, full-scale bridge models of a twin-steel trapezoidal box-girder bridge were constructed using K-type external cross-frames. Various failure modes, including the buckling and yielding of the cross-frames, were incorporated into the bridge models to account for realistic behaviors in the damaged bridge. The analysis results showed that the external cross-frames increased the load-carrying capacity of the bridge with one-girder fracture damage by transversely redistributing the live loads.

Composite bridges are typically exposed to temperature variations due to heat radiation, conduction, and convection. Temperature affects the modal parameters of bridges, hindering the application of damage detection methods based on the dynamic properties of bridges. In this study, the effects of temperature on the natural frequencies of composite bridges were investigated experimentally and numerically to derive a basis for separating temperature effects from the natural frequencies. A temperature-controllable girder specimen was developed for modal testing. Additionally, finite element (FE) analysis was conducted to analyze the effects of temperature. The FE analysis results were validated by comparing them to the static response results of the test specimen. The results of the experiments and FE simulations verified that temperature variation can affect the material properties, particularly the modulus of elasticity, of a composite girder, consequently influencing its natural frequency. Based on the tests and simulations, a linear relationship between the temperature and the natural frequency was proposed to remove the temperature effects from the natural frequency.

Dear Editor, We previously developed a novel paradigm of cell activation and signaling-directed （CASD） lineage conversion for direct reprogramming of fibroblasts into cardiac, neural and endothelial precursor cells. This method is based on the transient overexpression of iPSC factors （cell activation, CA） in conjunction with lineage-specific solu ble signals （signaling directed, SD）.

Parkinson’s disease (PD) is a well-known age-related neurodegenerative disease. Considering the vital importance of disease modeling based on reprogramming technology, we adopted direct reprogramming to human-induced neuronal progenitor cells (hiNPCs) for in vitro assessment of potential therapeutics. In this study, we investigated the neuroprotective effects of cryptotanshinone (CTN), which has been reported to have antioxidant properties, through PD patient-derived hiNPCs (PD-iNPCs) model with induced oxidative stress and cell death by the proteasome inhibitor MG132. A cytotoxicity assay showed that CTN possesses anti-apoptotic properties in PD-hiNPCs. CTN treatment significantly reduced cellular apoptosis through mitochondrial restoration, such as the reduction in mitochondrial reactive oxygen species and increments of mitochondrial membrane potential. These effects of CTN are mediated via the nuclear factor erythroid 2-related factor 2 (NRF2) pathway in PD-hiNPCs. Consequently, CTN could be a potential antioxidant reagent for preventing disease-related pathological phenotypes of PD.