Plasticity of Intestinal Epithelium: Stem Cell Niches and Regulatory Signals

The discovery of Lgr5+ intestinal stem cells (ISCs) triggered a breakthrough in the field of ISC research. Lgr5+ ISCs maintain the homeostasis of the intestinal epithelium in the steady state, while these cells are susceptible to epithelial damage induced by chemicals, pathogens, or irradiation. During the regeneration process of the intestinal epithelium, more quiescent +4 stem cells and short-lived transit-amplifying (TA) progenitor cells residing above Lgr5+ ISCs undergo dedifferentiation and act as stem-like cells. In addition, several recent reports have shown that a subset of terminally differentiated cells, including Paneth cells, tuft cells, or enteroendocrine cells, may also have some degree of plasticity in specific situations. The function of ISCs is maintained by the neighboring stem cell niches, which strictly regulate the key signal pathways in ISCs. In addition, various inflammatory cytokines play critical roles in intestinal regeneration and stem cell functions following epithelial injury. Here, we summarize the current understanding of ISCs and their niches, review recent findings regarding cellular plasticity and its regulatory mechanism, and discuss how inflammatory cytokines contribute to epithelial regeneration.     

Study on estimating electric potential in space between parallel electrodes

We have been studying on estimating distribution of permittivity between measurement electrodes using capacitance and electric potential. Two arc electrodes were separated by long distance and there electrodes were surrounded by additional electrodes respectively. In past research work, we carried out numerical electric analysis for calculating the capacitance and electric potential using Finite Element Method (FEM) and compared with experimental and numerical results. The capacitance values were almost agreed with experimental and numerical results. However, the electric potential values were different between experimental and numerical results in conventional studies. In this paper, we proposed an equivalent circuit including the stray capacity and measurement method for capacitance, the electric potential in space between long distance electrodes was estimated.     

Pressureless all-solid-state sodium-ion battery consisting of sodium iron pyrophosphate glass-ceramic cathode and β″-alumina solid electrolyte composite

In recent years, the expansion of demand for lithium ion batteries has resulted in soaring prices of the constituent resources. From the viewpoint of safety, studies on all-solid-state batteries are actively being carried out. In this study, we succeeded in driving all-solid-state batteries derived from nontoxic oxide glasses at room temperature without requiring scarce resources such as lithium and cobalt. The main structure of the ceramic batteries with a simple structure in which Na₂FeP₂O₇ crystallized glass and β″-alumina solid solution are joined by pressureless cofiring at 550°C. During the crystallization of Na₂O-Fe₂O₃-P₂O₅ glass, fusion with the β″-alumina solid solution is achieved. Reversible charge and discharge of 80 mAh/g were achieved at room temperature. It is not necessary to apply pressure during cell preparation or the use of the batteries. Furthermore, the strong junction at the cathode and electrolyte interface does not peel off during charge and discharge over a long period of 623 cycles. Ex situ X-ray photoelectron spectroscopy revealed partial Fe⁴⁺ induction and a reversible charge and discharge reaction even after overcharging to 9 V. It was demonstrated that Na₂FeP₂O₇ is very stable against overcharging to 9 V.     

Quantitative risk assessment using a Japanese hydrogen refueling station model

Although hydrogen refueling stations (HRSs) are becoming widespread across Japan and are essential for the operation of fuel cell vehicles, they present potential hazards. A large number of accidents such as explosions or fires have been reported, rendering it necessary to conduct a number of qualitative and quantitative risk assessments for HRSs. Current safety codes and technical standards related to Japanese HRSs have been established based on the results of a qualitative risk assessment and quantitative effectiveness validation of safety measures over ten years ago. In the last decade, there has been much development in the technologies of the components or facilities used in domestic HRSs and much operational experience as well as knowledge to use hydrogen in HRSs safely have been gained through years of commercial operation. The purpose of the present study is to conduct a quantitative risk assessment (QRA) of the latest HRS model representing Japanese HRSs with the most current information and to identify the most significant scenarios that pose the greatest risks to the physical surroundings in the HRS model. The results of the QRA show that the risk contours of 10^?3 and 10^?4 per year were confined within the HRS boundaries, whereas the risk contours of 10^?5 and 10^?6 per year are still present outside the HRS. Comparing the breakdown of the individual risks (IRs) at the risk ranking points, we conclude that the risk of jet fire demonstrates the highest contribution to the risks at all of the risk ranking points and outside the station. To reduce these risks and confine the risk contour of 10^?6 per year within the HRS boundaries, it is necessary to consider risk mitigation measures for jet fires.     

Cold-start performance of an ammonia-fueled spark ignition engine with an on-board fuel reformer

This work demonstrated the first-ever cold-start operation of an ammonia (NH₃)-fueled four-cylinder spark ignition engine with an on-board fuel reformer, applying autothermal reforming. In this system, an electrically heated NH₃-air mixture was provided to a reforming catalyst and approximately 3 s was found to elapse between the start of engine rotation and the onset of combustion. Stable fast idle operation in conjunction with a cold start was realized with a H₂-to-NH₃ molar ratio of 2:1. Nearly zero NH₃ emissions were achieved during cold start and fast idle until the engine warmed up, by adsorbing unburned NH₃ passing through a three-way catalyst before the catalyst was sufficiently warmed up. The NH₃ adsorption capacity of this system could be regenerated during the engine warm-up when the engine was running under lean conditions.     

Structures and mechanical properties of electrospun cellulose nanofibers/poly(ε-caprolactone) composites

Poly(ε-caprolactone) (PCL) is one of the ecofriendly biodegradable polymers with excellent moldability but with rather low mechanical properties especially for the industrial and biomedical use. In this research, to overcome the problem, the two types of cellulose nanofibers, the cellulose acetate nanofibers (CA-NF) and the cellulose nanofibers (C-NF), were composited into PCL for the enhancement of the mechanical properties of PCL. CA-NF were prepared by electrospinning and converted into C-NF afterward by deacetylation. It was found that the Young's modulus of the CA-NF/PCL composite at the fiber concentration of 35 wt% significantly increased by ~3 times as compared with that of neat PCL, whereas C-NF/PCL of the same fiber concentration also increased by ~4.5 times. It was also found that the Young's moduli of CA-NF/PCL nearly reached the theoretical values calculated by the equation suggested by Tsai, but that the Young's moduli of C-NF/PCL could not reach the theoretical values. It indicates that CA-NF possessed better compatibility with PCL than C-NF, agreeing well with the fracture-surface analyses of the two composites by the scanning electron microscopy.     

Reduction of Ripple Current Loss by Electromagnetic Coupling of Air‐Core Reactors

To reduce the loss due to ripple current in a multiphase current‐reversible chopper, we investigated electromagnetic coupling of an air‐core reactor. We derived the relationship between the amplitude of the ripple current, the duty factor, and the electromagnetic coupling coefficient, and used the results to estimate the effects of electromagnetic coupling in the design of a train energy storage system. We built reactors with electromagnetic coupling coefficients of 0.93 and 0.60. These reactors employed a new winding structure that provides an optimal electromagnetic coupling coefficient. The mass of the former type of reactor was increased by 4.4% over the conventional design, and that of the latter type of reactor was decreased by 17%. Finally, we tested the new reactors. When the chopper employs the former type of reactor and operates with equal‐phase switching and cumulative coupling, the loss due to ripple current is decreased by 11%. When the chopper employs the latter type of reactor and operates with shift‐phase switching and differential coupling, the loss is decreased to 31%. The test showed that the calculated relationships agreed with the measured values.