We examined the stability of urinary 8-hydroxy-2'-deoxyguanosine (8-OH-dG) when the sample urine undergoes several cycles of freezing and thawing. One hundred and two frozen samples (85 males and 17 females aged 22-79 years) were used. The concentration of urinary 8-OH-dG was measured by HPLC using two-step separations. We compared the 8-OH-dG level of samples after a second cycle of freezing and thawing with the level of samples after the first cycle (n=82). The mean urinary 8-OH-dG concentration after the first cycle and the concentration after the second cycle were 5.4 ± 2.8 ng/ml and 5.2 ± 2.8 ng/ml, respectively. There was no significant difference by the paired t-test. Regression analysis, with the 8-OH-dGconcentration after the second cycle as y and the 8-OH-dG concentration after the first cycle as x yielded y =0.97 × - 0.04 (R2=0.91, p<0.01). We then compared the 8-OH-dG level of samples after a third cycle with the level after the first cycle (n=20). The mean urinary 8-OH-dG concentration after the first cycle and the concentration after the third cycle were 5.9 ± 5.0 ng/ml and 6.2 ± 5.1 ng/ml, respectively. There was no significant difference by the paired t-test. Regression analysis, with the 8-OH-dG concentration after the third cycle as y and the 8-OH-dG concentration after first cycle as x yielded y = 1.0 × + 0.29 (R2 =0.96, p<0.01). We concluded that if the research purpose is the determination of urinary 8-OH-dG, samples can undergo at least three cycles of freezing and thawing without significant change.
Due to the fact that scaffolding is horizontally unstable, scaffolding collapse due to strong winds occurs frequently. As a countermeasure, scaffolding can be attached to a building using tie-bars. As the authors believed that scaffolding collapse due to strong winds was caused by failure of the tie-bars, several experimental studies to investigate their strength were carried out. Our studies indicated that tie-bars were sufficiently strong, leading us to the conclusion that tie-bars could be used safely. However, it became apparent that when construction was not performed with sufficient precision, there was a strong possibility of reduced tie-bar safety. In the present study, we tested experimentally the strength of a tie-bar fixed to an ALC panel. In the experiment, the compressive and tensile strength of four types of anchors were investigated. Results revealed that the strength of all anchors was considerably lower than that of the tie-bar. In fact, the strength of the anchors was less than 50% of the design strength of a tie-bar under almost all experimental conditions. Generally, in construction, the number of tie-bars is determined based on wind load and tie-bar strength. This study demonstrated that the number of tie-bars must be determined in conjunction with the strength of accompanying anchors.
Recently, there has been an increasing number of incidents and disasters in the chemical processes industry. The reasons include the following defective practices: inadequate safety management systems at companies, inadequate knowledge management and insufficient information on work or tasks, and no standardization of safety management activities. There is a strong need to standardize plant operation management and systematize safety management activities through plant lifecycle engineering of chemical processes. However, no study has been conducted to develop an activity model that will serve as a reference model for plant operation management. This paper proposes a reference model of plant operation management for preventing industrial accidents in chemical processes. The IDEF0 (Type-zero method of Integrated DEfinition for Function modeling) standard is employed as an activity modeling tool to describe the relations among plant operation management activities. To make clear its function as management model, this paper proposes a template in IDEF0 format which represents the PDCA (Plan, Do, Check, Act) cycle and resource provision. Based on this template, the activities for plant operation management are extracted and the appropriate activity model can be constructed. This reference model can be used as a normative guideline for plant operation management.
Trench collapses have caused loss of life and injuries to workers during construction. Due to the constrained space of the construction site, especially in urban areas, the angle of the trench corner has to be increased or decreased from the standard trench corner of 90 degrees, which might make the trench more prone to collapse. In order to investigate the effects of the trench corner angle quantitatively, a series of centrifuge model tests and 3D-FEM analyses were carried out in this study. The results showed that the stability factor, NS, was constant where the angle of the corner was more than 90 degrees. In contrast, the stability factor decreased when the angle of the corner was less than 90 degrees.
Recently, numerous explosions and fires due to static electricity have occurred during operations such as powder handling, dust collection, liquid flow and spraying. One effective way of avoiding electrostatic hazards is to carry out risk assessment based on the recommended practices and standard test methods. IEC TC 101 (static electricity) promotes international standardization to avoid electrostatic hazards and nuisances. The joint working group of IEC TC 101 and IEC TC 31 (explosion-protected electrical installations) discusses the draft of a new technical report based on CENELEC TR 50404 (Code of practice for the avoidance of hazards due to static electricity). JIS C 61340-4-4:2009, which is identical to IEC 61340-4-4:2005 (Standard test methods for electrostatic classification of flexible intermediate bulk container. FIBC), has been set. The draft of the second edition, which includes the use of inner bags, is under discussion by the IEC TC 101 working group. The draft of the revised edition for JIS T 8103 (Anti-static footwear to avoid the risk of ignition) that adopts IEC 61340-4-3:2007 (Standard test methods for footwear to avoid ESD damage to electronic components) has been prepared.