Search

This study evaluates the feasibility of a power generation system adopting pressure retarded osmosis (PRO) using seawater and fresh water. The authors measured the membrane power density of a commercially available hollow fiber membrane module. The power density of the current membrane module is 3.1 W/m2, but 6.5 W/m2 is required to realize a commercially feasible power plant adopting PRO. In this case of the net output power is 2.8 W/m2 when the DS pressure was 1.5 MPa and the FS pressure was 0.1 MPa, respectively. The cost of power generation is 0.20 $/kWh assuming a commercial plant that uses 1 million m3 of seawater per day and has the calculated membrane power density. It is necessary to improve the A and B values per membrane module to realize this system. Here, the A and B values are coefficients representing water permeability and salt permeability, respectively. The target membrane power density can be achieved using A and B values per membrane module of 2.05 × 10−6 m/s/MPa and 5.5 × 10−9 m/s, respectively. This evaluation is based on theoretical calculations using the solution-diffusion model of membrane permeation in PRO.

Sea water reverse osmosis (SWRO) would face some problems like energy saving and management of concentrated brine. To solve these problems at the same time, the energy recovery by Pressure Retarded Osmosis (PRO) was proposed in the Mega-ton Water System project. Prototype plant test was conducted using concentrated brine from SWRO plant and fresh water from regional waste water treatment facility. Hollow-fiber membrane module were examined in the prototype plant and the test operation was carried out for more than one year. We have reached the maximum membrane power density, 13.5 W/m2, using 10-in. module. Followings were still existing obstacles for further effective PRO. It was also challenging how to get clean fresh water from waste or river water without additional cost. Innovative new technologies were also required to address these concerns. We have also estimated plant cost and surveyed financial impacts on the energy saving of SWRO operation, based on the situation of currently operated SWRO plants worldwide, especially about the Mega-ton scale ones. Those studies indicated that potential market of PRO was 1–2 GW, and 10% energy saving was possible on the Megaton scale SWRO plants. Those results indicate that the commercialization plant would be available very near future.

We report the anesthetic management of a 65-year-old woman with recurrent, severe tracheal stenosis who underwent tracheal dilatation. She had visited the Department of Respiratory Medicine at our hospital for respiratory distress approximately 20 years ago, and had undergone laser ablation under local anesthesia. Because of recurrence and aggravation of respiratory distress, she now presented at the Department of Thoracic Surgery, and was scheduled for surgery. Percutaneous cardiopulmonary support was prepared, and she was sedated with midazolam and dexmedetomidine. Under bronchoscopic guidance, a 5-mm intubation tube was placed directly above the stenosis site. Laser ablation (by argon plasma coagulation) and balloon dilatation were performed, and the tube was replaced with one with a larger diameter, which was subsequently replaced with another with an even larger diameter. Ultimately, a 7-mm tube was placed beyond the stenosis site, and the operation was completed. After restoration of spontaneous respiration and consciousness, the patient was extubated in the operating room and returned to the intensive care unit. In anesthetic management of patients with tracheal stenosis, treatment of hypoxia is important. In this case, we collaborated with the attending physician, clinical engineers, and operating room nurses throughout, and consequently, were able to perform the operation safely.

Salinity power generation using hollow fiber modules was examined using the pressure-retarded osmosis (PRO) system between pure water and concentrated brine. Pure water and concentrated brine were supplied from a regional sewage treatment facility and sea water desalination (sea water reverse osmosis [SWRO]) plant. To minimize the effect of the concentration polarization near the membrane surface on the pure water side, the number of open ports in the module was increased from 3 to 4 and that modification was found to be effective because non-permeating pure water, which left the module through fourth port, flushed leaked salt from the brine side through the membrane. Our prototype PRO plant got the maximum output power density, 7.7 W/m2 at a 2.5 MPa hydraulic pressure difference and a 38% permeation of pure water into the brine. To remove the organic foulant in the pure water, a low pressure Reverse Osmosis (RO) membrane and coagulation–sedimentation method with ozonation showed good results. Ho...

The understanding of source and flow path of the groundwater provides important strategy for the environmental management of the mine area. Then, in order to clarify a source and flow paths of groundwater around a closed mine, stable isotopes of hydrogen and oxygen and water quality of river water and groundwater sampled from the mining shafts and levels in the Hosokura mine were studied. The hydrogen and oxygen stable isotopes indicating altitude effect for river water and the chemical character of sampled water suggest groundwater flows mainly from the north area of Hosokura mine to the ore bodies under the center of the mine area. The distributions of total head and darcy velocity calculated by the numerical simulation analysis show down streamlines from highland to the ore bodies and correspond well with the flow system estimated from stable isotopes and water quality of the sampled water.

四国西部の秩父累帯については，黒瀬川帯が認められないため，地体構造区分や構造層序に関して以前から種々の議論があった．秩父累帯北部に位置する大洲市南西部地域の構造層序と構成ユニットの帰属を検討し，新たな知見を得た．調査地域は，御荷鉾緑色岩類，古藪ユニットI・II，大洲ユニットI・IIに区分される．古藪ユニットIはチャートや緑色岩，石灰岩などから，古藪ユニットIIはチャートや砂岩，泥岩などから構成される．大洲ユニットは全体的に変成を受けており，泥質岩や砂質岩からおもに構成される．古藪ユニットは，ほぼ水平な断層を介して大洲ユニットに重なると推定される．岩相的特徴，緑色岩や砂岩の岩石学的・地球化学的特徴，泥質岩の変成白雲母K-Ar年代などを考慮すると，古藪ユニットIは南部秩父帯の三宝山ユニットに，古藪ユニットIIは同帯の斗賀野ユニットに対比され，大洲ユニットは白亜紀四万十帯の深部相に相当すると考えられる．

In the present study, composite polyelectrolyte membranes were prepared from sulfonated polystyrene and fullerene. The additive effect of the fullerene on the membrane properties – electric resistance, mechanical strength, oxidation resistance, and methanol permeability – were measured. The addition of fullerene improved the oxidation resistance, and reduced the methanol crossover. The mechanical strength of the fullerene-composite membrane, on the other hand, was not improved. The direct methanol fuel cell (DMFC) based on a 1.4 wt% fullerene-composite membrane showed the highest power density of 47 mW cm −2 at the current density of 200 mA cm −2 (this value is 60% of the Nafion-based DMFC). The transmission electron microscopy (TEM) observations suggest that the improved dispersity of the fullerene and the reduced number of micropores in the membranes would improve its performance in the fuel cell.

Faraday rotation spectra of Co/Pt multilayers were obtained in the region including Co M 2,3 and Pt N 6,7 absorption edges by using multilayer polarizers, and were transformed to magnetic circular dichroism (MCD) spectra by Kramers–Kronig analysis (KKA). From the dependence of the rotation angle on the layer thickness, it was suggested that the magnetization of Co tends to be uniform in Co layers and that of Pt is localized at Co/Pt interfaces. The orbital magnetic moment of Co was estimated to be about 0.17 μ B /Co. The similarity of electronic states around magnetized Pt site between Co/Pt multilayers and CoPt 3 alloy is suggested by the resemblance of the MCD spectra of both materials around Pt N 6,7 edges. In addition, magnetic Kerr rotation of Co/Cu multilayer was measured and was observed around Co M 2,3 and Cu M 2,3 absorption edges.

The use of photoelectron angular distributions to determine the linear polarization of VUV light over a wide range of photon energies is demonstrated. Light at wavelengths from 256 to 736 A, partially polarized by large angle reflections in a toroidal grating monochromator and at a refocus mirror, has been analyzed. The results are validated by comparison measurements at spot wavelengths using multilayer polarizers.

Composite multilayers consisting of a top single layer and piled double layers with high reflectance through a 200–30 nm wavelength range have been designed and fabricated for normal incidence optical systems and the performance was checked in a 140–30 nm range. The normal incidence reflectance of SiC (top layer)–Y 2 O 3 /Mg (double layers) multilayer was more than 14% in a range of 40–30 nm which is much higher than those of W, and 20–40% above 50 nm which is comparable with that of W. The reflectance of SiC (top layer)–Mg/SiC (double layers) multilayer was a little lower than those values.

A method for taking the fast-neutron profile has been developed using an imaging plate combined with a polypropylene converter. By this method, we can obtain the spatial distribution of fast neutrons without any γ-ray contamination by taking the difference between the data with and without the converter. We have studied properties of this method concerning the neutron energy, converter thickness, fading, dynamic range and spatial resolution. Under appropriate conditions, the method has more than a 102 dynamic range with linearity and less than 1.0 mm spatial resolution for 5 and 15 MeV neutrons. By using this method, we successfully obtained a fast-neutron profile after a collimator and radiography of a 5 cm thick iron block.

We developed a method of (n, α) cross-section measurement using a gaseous sample in a gridded ionization chamber (GIC). This method enables us to measure the cross section of gaseous samples, such as C, O and N, with very large solid angle close to 4π without distortion due to energy loss in the sample. The detection efficiency, which is difficult to estimate for gaseous samples, was estimated by using GIC signals and tight neutron collimation. This method was verified through the 12 C ( n , α 0 ) 9 Be cross-section measurement for 14.1 MeV neutrons.

To obtain the nuclear data for 237Np which plays an important role in high burn-up reactors and transmutation systems, we measured neutron-induced fission cross section ratios of 237Np relative to 235U between 6 and 120 keV using a pulsed white neutron source produced by the 4.5 MV Dynamitron accelerator of Tohoku University. The fission cross section ratios were measured by two separate runs with the experimental errors of 7% to 25%. The results by two separate runs agreed within the experimental errors. The fission cross section of 237Np was deduced by averaging two results and by using the fission cross section of U taken from JENDL3.2. The present results agreed with the result of Hoffman et al. and was consistent with the newest experimental result by Yamanaka et al. The present result around 10keV agreed with JENDL3.2, while those near 100 keV were close to ENDF/B-VI.

Double differential (n, α) reaction cross sections of 58Ni and natNi were measured for 4.2–6.5 MeV neutrons with energy resolution good enough to separate α-particles from the low-lying levels of residual nuclei by using a gridded ionization chamber. Angular distribution and excitation functions were derived for α0, α1 and αi≥2 components (α-particles to the ground level, the 1st level and levels higher than the 2nd level, respectively). The experimental results were compared with these obtained from calculation based on Hauser-Feshbach model employing the optical potential and the level density parameters derived to reproduce the experimental values of total, (n,p) and (n,α)cross sections. The calculation showed fair agreement with the experimental data while it underestimated the (n,α)cross section above 6 MeV.

Model calculations concerning the membrane potential and ionic fluxes in weak amphoteric polymer membranes have been presented and the results were compared with recent experimental data obtained with a membrane which contains succinyl chitosan as ampholyte and poly(vinyl alcohol) as supporting matrix. The ion transport through the membrane has been described with the aid of the Nernst—Planck equations, and the results obtained explain satisfactorily the observed experimental trends in broad ranges of pH and electrolyte concentration. Also, the model predictions concerning the membrane isoelectric point may be useful for the analysis of future experiments.

A study of the potentiometric behaviour of aqueous solutions of weak amphoteric polymers was carried out in advance of an investigation of weak polyamphoteric membrane prepared from a mixture of the amphoteric chitosan and poly(vinyl alcohol). Carboxymethyl chitosan and succinyl chitosan were used as weak polyampholytes. Succinyl chitosan is composed of amino and carboxyl groups, which were provided by substitution of the former with the latter. The portion of substituted groups from amino to carboxyl is represented by the degree of substitution ( DS ). Potentiometric titrations were performed with added salt of the 1-1 type or 2-1 type and without added salt. The behaviour could be rationalized through the dissociation mode concept based on a modified Henderson Hasselbalch relationship.

Piezodialysis in weakly amphoteric polymer membranes is discussed from the viewpoint of non-equilibrium thermodynamics. Succinyl chitosans were used as the weak polyampholytes. With varying pH in the outer solution, the apparent isoelectric point of the membrane was defined as the point of zero membrane potential, where solute permeation is much enhanced. Piezodialysis was confirmed from the phenomenological hydraulic permeability coefficients, reflection coefficients and solute permeability coefficients of the membrane, which were based on non-equilibrium thermodynamics. Permeation experiments with mixed ion systems were also performed. The permeation behaviour was in accordance with that expected for the interactions of ions with polyampholytes in aqueous solutions.

The membrane potential of a weakly amphoteric polymer membrane was measured by varying the dissociation state of the dissociative groups within the membrane through control of the pH of the outer aqueous solution, and the effective charge density of the membrane was evaluated. On the basis of a modification of the Teorell-Meyer-Sievers equation, we concluded that the difference between the charge densities of the positively and negatively charged dissociative groups seemed to play an important role in the permeation behaviour through the membrane. From the results of a study of the potentiometric behaviour of aqueous polyamphoteric solutions, it was confirmed that the ratio of the effective charge density to the net value could be estimated to be the same as that found previously.

A low-power microwave-excited argon microstrip plasma source operated at 2.45 GHz is studied by a three-dimensional fluid model. The electrodeless microwave-excited plasmas are produced in the gas channel with the gas pressures of 50 and 100 Torr at the input power of 2 W. Simulations are performed by the plasma module of COMSOL Multiphysics@. Results show that the electric field induced by the electromagnetic wave is concentrated in the neighborhood of the inner surface of gas channel under the microstrip line. The electromagnetic wave is restricted to transit from being propagating to evanescent in a very thin zone at which the electron density is equal to the critical density. The resonance zone is solved by adding an effective collision frequency to the momentum collision frequency. The governed ions are found to be atomic argon ions (Ar+) and molecular argon ions (Ar2 +) and the latter has a wider distribution. The three-body reactions to produce Ar2 + ions become important at high gas pressures.

A study of the effective charge density of a charged membrane composed of poly(vinyl alcohol) and poly(sulfonate) was carried out. The ratio of the effective charge density obtained from the membrane potential to the net charge density from pH titration was shown to be a function of degree of hydration (H). In order to explain the decrement of the ratio cited above as H increased, a model that includes two kinds of ionic fluxes within the membrane was introduced. This model was found to be able to give a qualitative explanation for the behaviour of the effective charge density of a charged membrane.

A tele-operation system for a crane is developed. The crane consists of a small actuator and a large actuator in x and y direction respectively. The large actuators are controlled by input signals from an operator and the small actuators are used as a regulator and feedback controlled by a wire angle sensor. Since a motion of the suspended object can be approximated as a second order system, overshoots of the object inevitably happen at the moment when the operator give a stop command to the system. To avoid this overshoots, a novel user interface is developed where operators indicate via points or target point of the object on a monitor screen from the camera imaging the scene below the crane. The system interpolates the via points by using four order functions and give the velocity commands to the crane until the inputs of the via points are stopped. The final point is regarded as the target point. From experimental results, the effectiveness of the developed control system and its control algorithm is verified.

Lithium isotope concentration profiles at the steady and unsteady states are obtained using the circuit for continuous displacement chromatography, which is composed of 2 cm i.d. columns packed with the strong-acid cation exchange resin, Diaion SK116 (100 μm). These profiles agree well with the results calculated assuming lithium adsorption bands to be square cascades in total reflux operation.

The effects of temperature and the use of macroreticular resins were studied in lithium isotope separation by an ion-exchange method. The isotope separation factors obtained decreased by increasing the temperature, and the factors for macroreticular resins were identical with those for the usual gel-type resins. However, the performance of isotope separation per unit band length in displacement chromatography was found to be improved by increasing the temperature and using macroreticular resins, because accelerating the interphase mass transfer caused the reduction of HETP (Height Equivalent to a Theoretical Plate).

Height equivalent to a theoretical plate (HETP), which is an important factor to determine separation performance, is experimentally obtained for lithium isotope separation by a circuit of continuous displacement chromatography. The values of HETP are related to the flow rates and concentrations of the displacement reagents. A new equation to estimate HETP is derived and shows good agreement with the experimental data. Diffusion in the resin is found to be the major resistance for the isotope exchange reaction, and liquid mixing in the columns also strongly influences the value of HETP.

Several different liquid distributors were manufactured and separately attached to the top of a large-sized, 50 cm i. d. ion exchange column. Effective dispersion coefficients of these distributors were measured by the stepwise response method, and were compared with those of smaller-sized columns. It was found that the use of an appropriate distributor enables one to scale up the column size without reducing the separation performance

On etudie les coefficients de dispersion radiale dans une colonne garnie d'un lit de resine echangeuse de cations pour de faibles vitesses d'ecoulement d'une solution diluee de NaCl