Assessment of a new ventricular contractile index obtained with transoesophageal echocardiography before and after cardiopulmonary bypass in cardiac surgical patients

Normal liver can tolerate even a right trisegmentectomy with caudate resection which results' in a reduction of liver volume by 80%, while a decompensated cirrhotic liver cannot tolerate even partial hepatic resection. This can be ascribed to decreased functional volume and the deterioration of individual hepatocyte function, which is caused and amplified by inappropriate intraoperative procedures and postoperative management. Problems related to liver diseases, including liver cirrhosis, jaundice and chronic active hepatitis, operative techniques and postoperative management should be considered during hepatic resection. Pathophysiology and tactics for handling these problems will be described.     

Investigation of pre- and post-dryout heat transfer of steam-water two-phase flow in a rod bundle

Pre- and post-dryout heat transfer experiments were performed for steam-water two-phase flow in a 5 × 5 rod bundle under conditions of total mass fluxes from 80 to 320 kg/m²s, inlet qualities from 0.1 to 0.8, heat fluxes from 3 to 26 W/cm² and a pressure of 3 MPa. Heater rod surface temperatures or heat transfer coefficients predicted by several correlations were compared with experimental data with emphasis on the applicability of the correlations to the present experimental conditions which were pertinent to thermal-hydraulic conditions during a LOCA in a nuclear reactor. The Chen and Biorge et al. correlations underestimated heat transfer coefficients in the pre-dryout region. The Varone-Rohsenow prediction which accounted for the thermal nonequilibrium effect, calculated heater rod surface temperatures relatively well in the post-dryout region over the whole region of the present experimental conditions. The Dittus-Boelter and Groeneveld correlations predicted heater rod surface temperatures relatively well in the post-dryout region under high total mass flux conditions, but underestimated considerably under low total mass flux conditions.     

Measurements of 220 GHz atmospheric opacity on Mt. Fuji with a radiometer/radome system

We measured atmospheric opacity at 220 GHz at the summit of Mt. Fuji (alt. 3776 m) about one year in order to explore a feasibility of submillimeter-wave astronomical observations. For this purpose, a 220 GHz radiometer system enclosed in a radome (51×51×62 cm³) has been developed. The 220 GHz opacity was lower than 0.06 for a significant fraction (～ 45 %) of time from November 1994 to March 1995. Diurnal variation of the opacity at the summit of Mt. Fuji is so small that continuous observation at submillimeter-wave is possible through day and night. Yearly variation of the opacity is studied from water vapor pressure data measured at the weather station for the past 3 years. To prevent accumulation of ice and snow on the Gore-Tex membrane in the radome, the outer membrane was supplied with a thermal flux of 0.63 kW m^?2 and the adjacent metal radome surfaces were supplied with a flux of ～0.9 kW m^?2. We evaluate from the 220 GHz transmission data that this heat flux is sufficient to keep the membrane on the radome free of ice and snow during 83 % of the time in 5 winter months. The summit of Mt. Fuji appears to be a promising site for submillimeter-wave observations.     

Micro wire-mesh sensor for two-phase flow measurement in a rectangular narrow channel

A micro wire-mesh sensor (μWMS) based on an electrical conductivity measurement between electrodes installed on the walls has been developed for gas–liquid two-phase flow measurements in a narrow rectangular channel. This measuring method applies a principle of conventional wire-mesh tomography, which can measure the instantaneous void fraction distributions in the cross-section of the relatively large flow channel. In two-phase flow measurement using μWMS the void fraction distributions in the narrow channel were obtained by the measured conductivities between electrodes arranged on each wall. Therefore, the gas phase structures and the bubble behaviors can be investigated in the flow channel with narrow gap. In the present paper, a μWMS for the air–water flow between parallel flat plates with a gap of 3 mm was developed and simultaneous measurements with a high speed video camera were conducted to compare the measured results in bubbly flow.     

Numerical analyses on liquid-metal magnetohydrodynamic flow in sudden channel contraction

Three-dimensional numerical calculations have been performed on the magnetohydrodynamic (MHD) flows through a rectangular channel with sudden contraction, particularly in order to estimate the pressure drop through the sudden contraction. The sudden contraction is in the directions both perpendicular and parallel to the applied magnetic field. The Hartmann number, the Reynolds number, and the magnetic Reynolds number were set to ～100, ～1000, and ～0.001, respectively, in simulating laboratory conditions. The continuity equation, the momentum equation, and the induction equation were solved numerically. In the sudden contraction in the direction perpendicular to applied magnetic field, the loss coefficient takes a positive value in all the cases performed in this study, contrary to the expectation. This result is in contrast to that in the sudden expansion in the direction perpendicular to applied magnetic field, where the loss coefficient generally takes a negative value due to the MHD effect. In the sudden contraction in the direction of applied magnetic field, the loss coefficient takes a positive and large value in all the cases performed in this study. The loss coefficient generally becomes larger than that in the case of corresponding channel expansion in the direction of applied magnetic field.     

Physicochemical properties of Ba(Zr,Ce)O3-δ-based proton-conducting electrolytes for solid oxide fuel cells in terms of chemical stability and electrochemical performance

To enhance the power generation efficiency of solid oxide fuel cells (SOFCs), the use of proton-conducting solid solutions of doped BaCeO₃ and doped BaZrO₃, with formulas of the Ba(Zr_0.1Ce_0.7Y_0.1X_0.1)O_3-δ (X = Ga, Sc, In, Yb, Gd), was investigated as SOFCs electrolyte materials with respect to both chemical stability and electrical conductivity. Regarding chemical stability, the weight changes of each material were measured under a CO₂ atmosphere in a temperature range of 1200 °C–600 °C.Higher chemical stability was observed for dopant ions with smaller radii. Regarding conductivity, the dependences of the total conductivities on the oxygen partial pressure and temperature were measured in the temperature range of 600 °C–900 °C. In each material, the total conductivity was proportional to the oxygen partial pressure to the 1/4 power at high oxygen partial pressures, as previously observed for accepter-doped proton-conducting perovskite-type oxides. The derived conductivities for each type of charge carrier showed that the hole conductivity increased with the ionic conductivity. Based on the measured data, the leakage current densities were calculated for SOFCs with each of the investigated electrolyte materials and an area-specific resistance of 0.383 Ωcm². BZCYSc showed the minimum leakage current density, with a value of 3.7% of the external current density at 600 °C. Therefore, this study indicates that BZCYSc is the most desirable among the materials investigated for use as SOFCs electrolyte. However, for BZCYSc to be used as SOFCs electrolyte material, a protective layer is needed to ensure its chemical stability.     

Pharmacokinetics of intravenous milrinone in patients undergoing cardiac surgery

BACKGROUND: Milrinone is a phosphodiesterase inhibitor with positive inotropic and vasodilator effects that are useful in the treatment of ventricular dysfunction after cardiac surgery. However, the pharmacokinetics of the drug have been investigated only in healthy volunteers and in patients with chronic congestive heart failure. This study investigates the pharmacokinetics of milrinone in adult cardiac surgical patients after cardiopulmonary bypass. METHODS: Milrinone was administered to 25 patients just before or immediately after separation from cardiopulmonary bypass. Arterial blood was sampled over the next 16 h and milrinone plasma concentrations were determined by high-performance liquid chromatography. Data were analyzed by extended nonlinear least-squares regression. The relation between milrinone plasma concentration and hemodynamic effect was examined in an additional 11 patients who had cardiac indices less than 2.5 l.min-1.m-2 immediately after separation from cardiopulmonary bypass. Milrinone was administered and plasma concentrations were related to changes in cardiac index during the next 10 min. RESULTS: A milrinone dose of 50 micrograms/kg in conjunction with an infusion of 0.5 micrograms.kg-1.min-1 consistently maintained plasma concentrations in excess of 100 ng/ml. A triexponential equation describing the plasma concentration as a function of time was used to describe the data. Central-compartment volume was 102 ml/kg, volume of distribution was 1,698 ml/kg, and elimination clearance was 1.88 ml.kg-1.min-1. Pharmacokinetic parameters were independent of dose. The relation between plasma concentration and percentage increase in cardiac index could be described by a sigmoidal curve with the plasma concentration associated with a 50% increase in cardiac index equal to 167 ng/ml. CONCLUSIONS: A milrinone dose of 50 micrograms/kg with an infusion at 0.5 micrograms.kg-1.min-1 maintains plasma concentrations at or above the threshold of therapeutic effects.     

Similarity study of ROSA-III and fist large break cuonterpart tests to BWR large break LOCA

A large break test in a recirculation pump suction line with the assumption of LPCI-diesel generator failure was conducted at the ROSA-III test facility of Japan Atomic Energy Research Institute. A counterpart test was also performed at the FIST test facility of General Electric Company. The objective of the tests was to develop common understanding and interpretation of the controlling thermal-hydraulic phenomena during a large break LOCA of a BWR. The fundamental thermal-hydraulic phenomena in the ROSA-III and FIST tests such as the system pressure, mixture level and fuel rod surface temperatures agreed well. The FIST test had more bundle uncovery than that in ROSA-III since lower plenum steam in the FIST test flowed out of the jet pumps when they uncovered allowing more liquid to drain from the bundle. The ROSA-III and FIST tests and a BWR counterpart were analyzed with the RELAP5/MODI (cycle 018) code. The similarity of the ROSA-III and FIST large break tests to a BWR large break LOCA has been confirmed through comparison of calculated results though they are slightly different in details. It is perhaps desirable to reexamine the DNB and interphase drag correlations and the jet pump models usedin the code.     

A new evaluation method of surface energy of ultra-thin film

A new method is proposed for evaluating the dispersive component of the effective surface energy of an ultra-thin film. The dispersive component is obtained by introducing a cut-off distance and integrating the corrected van der Waals pressure equation for a symmetric multilayer system. The cut-off distance is calculated using the experimentally determined surface energy of the substrate without an ultra-thin film. A stearic-acid Langmuir–Blodgett film on a glass plate was used as an ultra-thin film sample on a solid substrate. The dependences of the surface energy on the ultra-thin film thickness were investigated experimentally and theoretically, and the effectiveness of this method is discussed.     

Tomographic imaging of counter-current bubbly flow by wire mesh tomography

The objective of this work is to investigate characteristics of counter-current bubbly flow in a circular pipe with an inner diameter of 50 mm by using wire mesh tomography (WMT). The accuracy of WMT on void fraction measurement is also clarified by comparing the result with a non-intrusive optical method. The accuracy is within ±10%. Local void fractions of many flow conditions are reported. Local void fraction profile affected by superficial liquid velocity and bubble size is shown and discussed. Furthermore, intrusive effects, including bubble break-up and bubble deceleration, are also investigated. Bubbles passing a transparent wire mesh sensor (WMS) are investigated by the optical method. It is shown that bubbles are broken and decelerated by wires of the sensor. It can be concluded that the bubble break-up rate increase with increasing of bubble velocity. However, the bubble deceleration is not depending on the bubble velocity.