This paper discusses the maximum filling velocity for the prevention of incendive brush discharges on the surface of liquids in earthed tanks during filling operations, in which the maximum filling velocity has been adopted from the latest international standard regarding electrostatic hazards, IEC 60079-32-1 (2013). However, specific conditions related to tank diameter, height/diameter ratio of tanks, and the charge relaxation time (conductivity) of liquids are required to express the maximum filling velocity as one equation as a function of diameters of tank and inlet pipe. Nevertheless, the theoretical model itself used to obtain the filling velocity does not require such conditions. In this article, we describe the theoretical model, including a further generalized theory for the charge relaxation of charged liquids partially filled in an earthed tank, modified with respect to the effective charge relaxation time. Furthermore, we compare the maximum velocities between the standard equation and the modified theory and show its application to an actual operation of filling a tanker with xylene when the conditions for tank size and liquid conductivity do not satisfy the specified conditions.

Determining the relationship between the load generated by cooperative robots and the safety of human bone is essential while establishing technologies and standards in the field of cooperative robots. In this study, a three-point bending test to evaluate the strength of artificial bones has been proposed. First, the bending strength of an artificial radius and an artificial ulna is obtained through the bending test. Next, Finite Element Analysis (FEA) is used to estimate the bending strength of artificial bones. The bending strength of the artificial bones in four directions along a central axis is obtained along with the strengths and weaknesses for the load on each artificial bone in each direction. The FEA evaluation shows that the cancellous bones do not contribute to the strength of the other bones. In addition, efficacy of the FEA evaluation method is shown by comparing the strength of an artificial bone obtained through experiments with that determined using FEA. The comparison showed a difference of approximately 25% between the strengths obtained through the different methods, with the analytical result being the assessment of danger side.

Carbon nanotube (CNT) is a promising material that enhances the characteristics of plastic, because of this, its production volume is increasing. To evaluate CNT exposure in the workplace by carbon analysis, the size distribution of CNT aerosols is a key factor in separating CNT aerosols from ambient small particles. In this study, the mass size distributions of the simulated CNT aerosols were measured for samples collected using a Sioutas cascade impactor. Both monomodal and bimodal distributions were observed. Thinner CNTs tended to show monomodal distribution in the scanning electron microscopic observations because they contained strong agglomerates of tangled fiber.

The statistical analysis about industrial accidents offers various basic information in decision of accident preventive measures. In this paper, frequency and severity were analyzed by the accident scale curve about the explosion / fire accidents. In the analysis, casualties was used as the accident scale and cumulative probability was used as the density function of frequency. On the log-log graph, the relationship of the cumulative probability of casualties and the accident number was shown in a straight line. The gradient of the straight line expresses severity. The combination of this severity and frequency was analyzed. In the case of all industries, the frequency decreased first with the pass of years. After that, severity decreased. The severity of the chemical industry was higher than the severity of the construction industry clearly. However, each trend of the severity with athe pass of years was indefinite. In addition, the analysis results about changes by the type of industry or accident were shown.

We evaluated the particle collection efficiencies of four types of polytetrafluoroethylene (PTFE)-coated glass fiber filters. The efficiencies were tested with 10 sizes of monodispersed aerosols from 30 to 500 nm. The efficiencies

corresponding to each particle size were obtained by measuring particle number concentrations upward and downward of the filter set in the NWPS-254 sampler. The results showed that each filter satisfied the efficiency of more than

95% for particle size of 300 nm under the Working Environment Measurement Standards of Japan. On the other

hand, the efficiencies ranged from 87.0% to 99.7% when particle size was approximately 100 nm.

3,3’-dichloro-4,4’-diaminodiphenylmethane (MOCA), an industrial chemical used as a curing agent for polyurethane pre-polymers, is known as a carcinogen that may cause occupational bladder cancer. Generation of DNA damage is a crucial first step in carcinogenesis, and it is clear from the previous studies that MOCA is genotoxic. On the other hand, it is still unknown whether MOCA produces a DNA double strand break, the most severe DNA damage closely related to carcinogenesis. In addition, there are no studies comparing genotoxicity between MOCA and the substances having similar chemical structures and using same application as MOCA. In this study, in order to grasp the hazard of chemical substances accurately, we carried out comparison of DNA damage properties among MOCA, 4,4’-diaminodiphenylmethane, 4,4’-diamino-3,3’-dimethyldiphenylmethane, and 4,4’-dihydroxydiphenylmethane using phosphorylated histone H2AX, having attracted attention in recent years as a biomarker of DNA doublestrand breaks. We found that all four tested substances induced γH2AX, and the induction was particularly strong in MOCA and 4,4’-dihydroxydiphenylmethane. The findings of this study are considered to provide important information for risk assessment of tested substances.