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.     

Polarity Effect and Electromagnetic Radiation of Partial Discharge Accompanying Growth of Electrical Tree

We have investigated the characteristics of radiated electromagnetic (EM) waves from positive and negative partial discharges (PD) in epoxy resin and cross‐linked polyethylene. We found that there is a correlation among the EM level from PD, the positive PD current, and electrical trees. Therefore, the growth of an electrical tree produces a lot of positive PD. We have also investigated the characteristics of the frequency region of EM waves from PD in air, insulating oil, and liquid epoxy in addition to the above insulators. EM waves were detected in the frequency region of 40 MHz to 300 MHz from positive and negative PD in epoxy resin and cross‐linked polyethylene. EM waves were also detected in the frequency region of 40 MHz to 150 MHz from positive and negative PD in air. In the case of insulating oil and liquid epoxy, EM waves were detected in the frequency regions of 40 MHz to 150 MHz from positive PD, and 40 MHz to 250 MHz from negative PD. The frequency region differed depending on the material and the discharge polarity. Our investigation indicates that the cause is differences in electric field strength at the time of PD occurrence.     

Effects of Surface Concentration on Drying Behavior of Carbohydrate Solutions

As the surface properties of the drying materials are very important not only for the drying rate but also for the quality change during drying, the effects of surface concentration on the drying behavior of liquid foods (sugar solutions) were investigated by isothermal drying experiments and by numerical calculation experiments. The isothermal drying experiments with gelled sugar solution systems (sucrose and maltodextrin) were carried out at various relative humidity (RH) values (RH = 0 to 84%). Separate experiments were carried out for determination of the desorption isotherms.

The isothermal drying curves of sugar solutions at RH = 0 to 51% were very similar. Numerical simulations also showed that the drying curves of these sugars at the surface concentration = 0 and 0.1 are almost the same, although the concentration distributions are different.

When a small amount of gelatin was added to sugar solutions, the drying rate decreased remarkably as the gelatin might form a thin film (skin) near the surface, and consequently the retention of ethanol increased.     

A technique of minilaparotomy-assisted vaginal hysterectomy

PURPOSE: To report a patient with acute retinal pigment epitheliitis examined less than 24 hours after onset of symptoms. METHOD: One day after the onset of blurred vision in her left eye, a 33-year-old woman had a best-corrected visual acuity of LE, 20/60 -2. The left eye had classic uniform golden-colored nodules in a honeycomb pattern in the foveal retinal pigment epithelium. Intravenous fundus fluorescein angiography disclosed staining of the foveal pigment epithelium. RESULTS: One month after initial examination, visual acuity was LE, 20/20, and fine subfoveal pigmentary clumping was present. CONCLUSION: The pigmentary maculopathy of acute retinal pigment epitheliitis may be nonspecific, resulting from more than one type of primary foveal inflammation.     

The significance of colocalization of plasminogen activator inhibitor-1 and vitronectin in hepatic fibrosis

BACKGROUND: We examined the relationships among vitronectin (VN), plasminogen activator inhibitor-1 (PAI-1), and transforming growth factor beta 1 (TGF-beta 1) in liver diseases to evaluate the presence of plasmin cascade in human hepatic fibrosis. METHODS: Blood and liver tissues were obtained from 57 patients with liver disease. Plasma VN, PAI-1 antigen, and PAI-1 activity levels were evaluated. Biopsied liver specimens were observed by light and electron microscopy after immunohistochemical staining. Morphometric analysis was performed on these specimens. RESULTS: Plasma VN and PAI-1 activity levels decreased significantly with the progression of hepatic fibrosis and were particularly marked in the liver cirrhosis group. Plasma PAI-1 antigen level increased significantly. The immunolocalization of the active form of TGF-beta became more intense with the progression of hepatic fibrosis, whereas that of the dual-stained positive areas of PAI-1 and VN (PAI-1.VN) decreased. There was a positive correlation between TGF-beta and PAI-1, whereas there was a negative correlation between TGF-beta and PAI-1.VN. Immunoelectron microscopy showed the localization of PAI-1-VN in the extracellular space around the sinusoidal cells or surface of aggregating platelets, TGF-beta mainly in Ito cells, and VN in hepatocytes near the focal necrotic area or fibrous septa. CONCLUSIONS: These findings suggest that VN and PAI-1 are related to the active form of TGF-beta and that it is possible that the plasmin cascade is present in the human liver.     

The levels of integrin alpha v beta 5 may predict the susceptibility to adenovirus-mediated gene transfer in human lung cancer cells

Adenovirus mediated transfer of growth-inhibiting molecules, such as p53 shows promise as an effective method of suppressing the growth of cancer cells. As the basis for in vivo studies, we examined transfection efficiency using 15 human lung cancer cell lines that differ in their endogenous p53 status. When infected with an adenovirus expressing bacterial beta-galactosidase, the different cell lines showed different levels of beta-galactosidase activity. We found a correlation between the level of integrin alpha v beta 5, which is thought to be an adherence receptor for adenoviruses, and the expression level of the transferred gene, suggesting that gene expression is largely dependent on the infection efficiency. Growth inhibition was induced in all cell lines tested following infection with an adenovirus containing p53, regardless of the genetic status of their endogenous p53 provided a sufficient amount of p53 protein was expressed. Our results (1) confirm that the examination of the susceptibility of target cancer cells to an adenovirus is important when considering performing adenovirus-mediated gene transfer and for evaluating its therapeutic effects; and (2) suggest that the quantification of integrin alpha v beta 5 may be a good way of predicting the susceptibility of cells to adenoviral vectors.     

An equation of state for 1,1-difluroethane (HFC 152a)

An equation of state for 1,1-difluoroethane (HFC 152a, CH₃CHF₂) has been developed on the basis of reliable experimental data including PVT, liquid C_p, and saturated-liquid-density data measured by our group. It is a non-dimensionalized virial equation whose functional form is the same as that originally developed for 1,1,1,2-tetrafluoroethane (HFC 134a) in our group. The effective range is for pressures up to 15 MPa, temperatures from 230 to 450 K, and densities to 1000 kg m⁻³. The equation represents reliable PVT measurements within ± 1% in pressure for the superheated vapour and supercritical fluid, while within ±0.5% in density for the compressed liquid. In addition, it should be noted that the equation represents the other essential thermodynamic properties including vapour pressures, saturated-liquid/ vapour densities, isobaric/isochoric specific heats and sound velocity in both the liquid and gaseous phase of HFC 152a.