Little is known about the growth patterns of low birth weight neonates (<2500 g) during standardized thermal control and nutrition regulation to meet basal metabolism requirements compared to those of non-low birth weight neonates (2500 g and above). We retrospectively identified 10,544 non-low birth weight and 681 low birth weight neonates placed in thermo-controlled incubators for up to 24 h after birth. All neonates were fed a 5% glucose solution 1 h after birth and breastfed every 3 h (with supplementary formula milk if applicable) to meet basal metabolism requirements. Maximum body-weight loss (%), percentage body-weight loss from birth to peak weight loss (%/day), and percentage body-weight gain from peak weight loss to day 4 (%/day) were assessed by multivariable linear regression. Overall, the growth curves showed a uniform J-shape across all birth weight categories, with a low mean maximum body-weight loss (1.9%) and incidence of neonatal jaundice (0.3%). The body-weight loss patterns did not differ between the two groups. However, low birth weight neonates showed significantly faster growth patterns for percentage body-weight gain: β = 0.52 (95% confidence interval, 0.46 to 0.58). Under thermal control and nutrition regulation, low birth weight neonates might not have disadvantages in clinical outcomes or growth patterns.
The internal structure of a blast containment container has been developed and examined by experiments involving the explosion of a high explosive. A steel pipe was selected as an effective structure for blast mitigation, because it dramatically reduces the blast wave in the radial direction near the explosion source. To also reduce the blast wave in the axial direction, two types of model structures consisting of a steel pipe as the main part were examined by both high-speed photography and pressure measurements of the blast waves. A 0.34-scale internal structure was constructed by combining these structures. To induce a powerful mitigation effect, the internal structure was filled with a shock-absorbing material. The peak pressures of C4 explosions in free air were obtained on the basis of the published blast wave data for TNT explosions in free air using an equivalent weight of 1.37. The peak pressures of the blast waves from the structures for all cases were compared with the blast wave data for C4 explosions in free air to estimate the blast mitigation effect. As a result it was estimated that the internal structure not only eliminates the blast pressure in the radial direction but also reduces the blast wave in the axial direction by 36 %. By combining the effects of the internal structure and the shock-absorbing material, the structure can reduce the peak pressure by 75 %.
The high speed photography, pressure measurements and numerical simulation of gap test of the high explosive have been carried out. The height of donor is 50 mm with 26 mm inner diameter, and that for acceptor charges is varied. When the gap length is 22.8 mm or large, the sympathetic detonation was not confirmed. Although the detonation does not occur, the gas expansion from the acceptor appears as the results of remarkable decomposition if the gap length approaches 23 mm. Those phenomena are very important on the point of view of the safety engineering. Finally, the parameters of initiation model which could reproduce the behaviors of high explosive around the critical condition were constructed.
Fundamental properties of a shock compaction technique of applying converged underwater shock waves have been investigated for rare earth magnet powders. The rare earth magnet made from Fe-Nd-B powder is being developed to have a high magnet performance. Usually this powder is consolidated using static high pressure and bond materials. It is very difficult to obtain over 80% magnet purity and, thus, it is difficult to achieve maximum performance. To solve this problem, shock compaction techniques involving use of explosives were tested and the results are presented here. The equation of state (EOS) of Fe-Nd-B powders is first verified by a quasi -static experiment. The applicability of the EOS is confirmed by a new shock loading test which is proposed in this paper. Both numerical simulation and experiments on the consolidation of the magnet poweders are carried out. A fine-bonded bulk with of over 96% is obtained.
In this paper, a generalized procedure of providing p-v-ε equation of state (EOS) is developed based on the hydrostatic compression data with Birch-Murnaghan form of the isotherm. Obtained formula can be used to calculate Grüneisen EOS with arbitrary specific heat as a function of entropy, Cv(S), and arbitrary Grüneisen volume function, γ(v). It is found that different Grüneisen function gives only slight effects on EOS and p-v shock Hugoniot. On the contrary, T-v shock Hugoniot strongly depends on Cv(S) function. Constant Cv(S) gives overestimated high shock temperature TH, while linear Cv(S) gives much lower value, and intermediate function may give appropriate TH values.
