Hemodynamic Performance of the Biventricular Bypass System Operated in an Independent Variable Rate Mode

The present study was undertaken to determine whether a biventricular bypass system operated in an independent variable rate (VR) mode can maintain the entire circulation. Two pusher-plate pumps which incorporated the Hall effect position sensors were used to bypass the right and left ventricles in 10 sheep under fibrillation. The flow distributions of the pump output to the carotid and renal arteries were investigated every 6 h using ultrasonic blood flow meters for 24 h in 5 animals, and the controllability of the VR mode was evaluated in 5 long-term experiments. The carotid artery flow ratio to the pump output decreased significantly from 4.7 +/- 0.8% before the bypass to 2.7 +/- 0.9% after 24 h. However, the renal artery flow ratio did not change throughout the experiments. In the long-term experiments, the animals were kept alive from 3 to 48 days (mean 15.6 days). The mean pump output had been maintained at more than 90 ml/min/kg for the first 7 days. After the surgery, the pump driving conditions were not readjusted in any experiment. The results indicate that the biventricular bypass system operated in the independent VR mode automatically maintains the entire circulation at a satisfactory level.</p

Development of Methods to Evaluate Several Levels of Uranium Concentrations in Drainage Water Using Total Reflection X-Ray Fluorescence Technique

As a country's law stipulates the effluent standard uranium concentration in drainage water, the uranium concentration must be determined when drainage water is released from a uranium handling facility, such as the Fukushima Daiichi nuclear power plant. The maximum allowable limit for uranium release at each facility is defined taking into consideration the situation of the facility, such as 1/10 to 1/100 of this effluent standard value. Currently, the uranium concentration of drainage water is commonly determined by α-particle spectrometry, in which several liters of drainage water must be evaporated, requiring about half of a day followed by 2–3 h of measurements, due to the low specific radioactivity of uranium. This work proposes a new methodology for the rapid and simple measurement of several levels of uranium in drainage water by a total reflection X-ray fluorescence (TXRF) analysis. Using a portable device for TXRF measurements was found to enable measurements with 1/10 the sensitivity of the effluent standard value by 10 times condensation of the uranium-containing sample solution; a benchtop device is useful to measure uranium concentrations &lt;1/100 of the effluent standard value. Therefore, the selective usage of methods by a portable and benchtop devices allows for screening and precise evaluation of uranium concentrations in drainage water

X-ray fluorescence in biological sciences

For rapid detection of uranium contamination in wounds at a nuclear fuel handling facility, a technique for XRF analysis of blood collected on small filter paper was developed, and a minimum detectable radioactivity of 0.31 mBq was obtained. This is much smaller than the lower detection limit of 1 Bq of the α-particle survey meter. This very simple and rapid technique has enabled the detection of uranium contamination in wounds with much higher sensitivity

X-ray Fluorescence-based Screening Method for Uranium Contamination

Uranium, which is used as nuclear fuel, is a radioactive material, and screening for uranium contamination is often performed by radiation measurements. However, a method targeting the number of atoms is more effective than radiation measurements for detecting uranium, which is a long-half-life nuclide with very low specific radioactivity. X-ray fluorescence analysis is one such analytical method that is suitable for screening measurements because of the simple pretreatment required. In this article, the properties of uranium and the superiority of X-ray fluorescence analysis as a screening method for uranium contamination are described first. Furthermore, we provide a comprehensive overview of screening methods based on X-ray fluorescence (XRF) analysis for uranium-contaminated wounds, on the basis of our recent studies. These methods can be used in radiation emergency medicine. In addition, we discuss methods based on total reflection X-ray fluorescence (TXRF) analysis for analyzing uranium-contaminated drainage water which will be found in the decommissioning field of Fukushima Daiichi Nuclear Power Plant

Trace determination of uranium preconcentrated using graphene oxide by total reflection X‐ray fluorescence spectrometry

A new method based on dispersive microsolid phase extraction using graphene oxide (GO) as a solid adsorbent and total reflection X‐ray fluorescence (TXRF) spectrometry is proposed for trace determination of uranium. In the developed methodology, a suspension of GO was injected into uranium‐spiked multielement solutions including rubidium; after filtration, the membrane filter with collected GO was placed in a small volume of internal standard acid solution and the eluent containing uranium was deposited onto a fluorine resin‐ coated slide glass, which is a disposable sample stage. Using GO was effective for removal of rubidium from the measurement solution to avoid interference between Rb Kα peak and U Lα peak. The high enrichment factor of 150 enables obtaining uranium detection limits of 0.042, 0.087, and 0.12 μg L−1 for ionic strength of 0.01, 0.1, and 1 mol L−1, respectively. Such low detection limits were obtained by using a benchtop TXRF spectrometer with 5‐min measurement. The proposed method is suitable for trace uranium determination in water, including high salinity samples