Filtration extraction method using a microfluidic channel for measuring environmental DNA.

The environmental DNA (eDNA) method, which is widely applied in biomonitoring, is limited to laboratory analysis and processing. In this study, we developed a filtration/extraction component using a microfluidic channel, the Biryu-Chip (BC), and a filtration/extraction method, the BC method, to minimize the volume of the sample necessary for DNA extraction and subsequent PCR amplification. We tested the performance of the BC method and compared it with that of the Sterivex filtration/extraction method using aquarium and river water samples. We observed that using the BC method, the same concentration of extracted DNA was obtained with 1/20-1/40 of the filtration volume of the Sterivex method, suggesting that the BC method can be widely used for eDNA measurement. In addition, we performed on-site measurements of eDNA within 30 min using a mobile PCR device, demonstrating that filtration and extraction can be performed easily and quickly using the BC method. The PCR results obtained using the BC method were similar to those obtained using the Sterivex method. The BC method requires fewer steps; therefore, the risk of DNA contamination can be reduced. When combined with mobile PCR, the BC method can be applied to easily detect eDNA within 30 min from the collection of water sample, even on-site.

On-site environmental DNA detection of species using ultrarapid mobile PCR.

Molecular methods, including those for environmental DNA (eDNA), provide essential information for biological and conservation sciences. Molecular measurements are often performed in the laboratory, which limits their scope, especially for rapid on-site analysis. eDNA methods for species detection provide essential information for the management and conservation of species and communities in various environments. We have developed an innovative novel method for on-site eDNA measurements using an ultrarapid mobile PCR platform. We tested the ability of our method to detect the distribution of silver carp, Hypophthalmichthys molitrix, in rivers and lakes. Our method reduced the measurement time to 30 min and provided high detectability of aquatic organisms compared to national observation surveys that use multiple fishing nets and laboratory extraction/detection using a benchtop qPCR platform. Our on-site eDNA method can be immediately applied to various taxa and environments.

Case study on possible falling patterns of a fatal fall from stairs.

Considering a fatal case of an aged individual, who died due to falling down stairs, the cause of the fatal fall was investigated through experiments. A witness, who was with the victim, when the fatal accident occurred, stated that the aged individual had miss-footed, lost balance at the top of the stairs, and fell accidently from an upper floor to a lower floor. It was very questionable whether or not this witness's statements were true. The true cause of the fatal fall was unclear, because of the witness's inconsistent statements, which showed discrepancies between the initial and later statements. The cause of a fatal fall can be presumed from external and internal damages to the body and other circumstantial evidences. But it was difficult to prove the true cause of a fatal fall only from the results of the autopsy and investigation of circumstantial evidences. The author was officially requested to conduct experiments to elucidate possible falling patterns. Judging from the experimental results, deep questions about the witness's statements arose. These experimental methods and analyses in this paper could be applied to elucidate possible falling patterns of fatal falls from stairs where the fatal causes are controversial.

Research on slip resistance measurements--a new challenge.

Slips, trips and falls are one of the most common causes of injuries and fatalities in the general community and industry. The control of such incidents involves a complex array of factors including the characteristics of each individual's footwear and gait dynamics, walking and working surfaces, and environmental conditions. Notwithstanding this complexity, slip resistance properties have been widely measured as a form of coefficient of friction (COF) index at the sliding interface between the shoes and floors. Since the COF measurements were commonly adopted to evaluate slip potentials, it has been found that there were controversies in the interpretation of COF measurement results. This study, therefore, was principally focused on broadening the knowledge base and developing new ideas on which improvements in the validity and reliability of slip resistance measurements might be made. To achieve this goal, crucial problems on the current concept of slip resistance measurement were extensively analysed by a tribological point of view where principle understanding of the shoe-floor friction and wear phenomena could be made. Based on this approach, new theoretical models were suggested.

Analysis of backward falls caused by accelerated floor movements using a dummy.

This investigation used a standing dummy on slippery and non-slippery surfaces with accelerated movements of a floor to simulate falling backward events. The results revealed the duration of falling, head impact velocity, etc., which are valuable for guiding the development of personal protective equipment, such as wearable airbags. The mechanism, by which a dummy falls backwards due to abrupt accelerated movements of a floor, was studied. A small linear accelerator was designed to apply a series of 20 combinations of step-shaped accelerations of varying durations to cause a standing dummy to fall backwards. Two flooring surfaces, namely, a smoothed aluminum surface sprayed with mould lubricant and a surface with abrasive materials, were used. Ankle, knee and hip joints of the dummy were adjusted in fixed or unfixed positions. When the dummy fell backwards like a rigid body, the head impact velocities were almost constant at around 22 to 23 km/h, and the mean duration of falling to the ground was 0.83 s, when standing on a slippery surface, and 0.98 s when standing on a non-slippery surface. The duration of falling to the ground tended to converge at 0.8 s as the maximum velocity of accelerated movements of the floor increased, irrespective of the frictional properties of the flooring surfaces.