Influence of voltage rise time on oxidation treatment of NO in simulated exhaust gas by polarity‐reversed pulse discharge

This paper describes an experimental study of NO removal from a simulated exhaust gas by repetitive surface discharge on a glass barrier subjected to polarity‐reversed voltage pulses. The very fast polarity‐reversal with a rise time of 20 ns is caused by direct grounding of a charged coaxial cable 10 m in length. The influence of the voltage rise time on energy efficiency for NO removal is studied. The results of NO removal using a barrier‐type plasma reactor with a screw‐plane electrode system indicate that the energy efficiency of very fast polarity reversal caused by direct grounding is higher than that of slower polarity reversal caused by grounding through an inductor at the cable end. The energy efficiency of direct grounding is approximately 80 g/kWh for a 50% NO removal ratio and approximately 60 g/kWh for a 100% NO removal ratio. Very intense discharge light is observed at an initial time of 10 ns for fast polarity reversal, whereas the intensity of the initial discharge light for slower polarity reversal is relatively small. To confirm the effectiveness of the polarity‐reversed pulse application, a comparison of the energy efficiency of polarity‐reversed voltage pulses and an AC 60‐Hz voltage is presented. © 2011 Wiley Periodicals, Inc. Electr Eng Jpn, 178(4): 32–38, 2012; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21215     

CO2 bubble nucleation in polystyrene: Experimental and modeling studies

Polymer foams are used extensively in a variety of applications. A firm understanding of bubble nucleation is vital to predict foam properties based on process conditions. However, a number of theoretical and experimental challenges have thus far limited progress in this area. We propose the use of a scaling theory to connect nucleation behavior to well understood bulk phase behavior of polystyrene-CO₂ systems, which can be predicted by equations of state, such as the Sanchez–Lacombe equation of state. Scaling theory of nucleation asserts that when the reversible work of critical nucleus formation is properly normalized and plotted against the normalized degree of supersaturation, the resulting scaling curve is insensitive to temperature and the materials being used. Once the form of the scaling function is known, it can be used to predict the nucleation barrier knowing only the initial foaming conditions and calculating only bulk thermodynamic values. Using an extension of diffuse interface theory, we determined the slope of the scaling curve near saturation. This initial slope allows us to constrain the scaling function for better predictions of the reversible work. We also performed a series of experiments to help verify the accuracy of the scaling theory. The scaled free energy barriers determined from our experiments are consistent with the scaling function so constructed, and our theoretical results qualitatively agree with those found previously. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Moving-Wheel Fatigue for Bridge Decks Strengthened with CFRP Strips Subject to Negative Bending

This paper presents the negative bending of reinforced concrete slabs strengthened with near-surface mounted (NSM) carbon fiber-reinforced polymer (CFRP) strips. Six slab specimens, three of which are strengthened with CFRP strips, are tested in static and fatigue loads. A wheel-running fatigue test machine is used to simulate vehicular loads on a bridge deck. The effectiveness of CFRP strengthening for bridge decks in cantilever and pseudonegative bending is examined based on moment-carrying capacity and cyclic behavior under the wheel-running fatigue loads, including crack patterns and damage accumulation. The moment-carrying capacity (static) of the cantilever slab strengthened with the NSM CFRP strips is improved by 68.4% when compared to that of an unstrengthened slab. The damage accumulation rate of the strengthened cantilever slab owing to the fatigue load is significantly lower than that of the unstrengthened slab. The damage accumulation of the strengthened slab gradually increases and is irreversible when the fatigue cycles increase. The fatigue-induced flexural cracks of the slabs develop along the wheel-running direction. A simple predictive model is presented to estimate the fatigue life of the test slabs.     

Large-scale preparation of cytosolic and mitochondrial asparatate aminotransferases from pig heart

A procedure is described for the large-scale preparation of the cytosolic and mitochondrial isoenzymes of aspartate aminotransferase from pig heart. The procedure consists of: 1. extraction of both isoenzymes by heat treatment of homogenates prepared from minced and frozen heat muscle; 2. separation of each isoenzyme on a hydroxyapatite column; 3. purification of each isoenzyme by combinations of heat treatment, ammonium sulfate fractionation and chromatography on ion-exchange cellulose columns. Purified preparations of each isoenzyme thus obtained were homogeneous proteins as judged from their spectral properties and behavior on polyacrylamide gel electrophoresis. Using the present procedure, 1.2 g of the cytosolic isoenzyme and 1.7 g of the mitochondrial isoenzyme were obtained from 20 kg of minced heart muscle.     

Transesterification of phytosterol and edible oil by lipase powder at high temperature

Phytosterol, which is hardly soluble in edible oil, was solubilized at a high concentration by converting it to FA esters by lipase-catalyzed transesterification at temperatures higher than 100°C using powdered Lipase QLM (Meito Sangyo Co., Ltd., Nagoya, Japan). Transesterification was conducted, in sunflower oil containing 10% phytosterol, without adding water or solvent, at 100°C. The conversion rate was 97.1% after 7 h of reaction. The effect of temperature on the conversion rate was also examined. Maximum enzyme activity occurred in the 100–120°C range, and 20% of the maximum activity was retained even at 130°C. When the lipase was recovered by filtration and recycled for repeated reactions at 90°C, the half-life of lipase activity was 260 h. Thus, edible oils with nutritional value could be produced by blending the phytosterol-containing sunflower oil into other edible oils.     

Synergistic hydrogen production by nuclear-heated steam reforming of fossil fuels

Processes and technologies to produce hydrogen synergistically by the nuclear-heated steam reforming reaction of fossil fuels are reviewed. Formulas of chemical reactions, required heats for reactions, saving of fuel consumption, reduction of carbon dioxide emission, and possible processes are investigated for such fossil fuels as natural gas, petroleum and coal.

In this investigation, examined are the steam reforming processes using the “membrane reformer” and adopting the recirculation of reaction products in a closed loop configuration. The recirculation-type membrane reformer process is considered to be the most advantageous among various synergistic hydrogen production processes. Typical merits of this process are; nuclear heat supply at medium temperature around 550°C, compact plant size and membrane area for hydrogen production, efficient conversion of a feed fossil fuel, appreciable reduction of carbon dioxide emission, high purity hydrogen without any additional process, and ease of separating carbon dioxide for future sequestration requirements.

The synergistic hydrogen production using fossil fuels and nuclear energy can be an effective solution in this century for the world which has to use fossil fuels to some extent, according to various estimates of global energy supply, while reducing carbon dioxide emission.     

Numerical investigation of multi-dimensional characteristics in sodium combustion

Multi-dimensional sodium combustion behavior has been numerically investigated in the present paper. A new computer code AQUA-SF has been developed for this purpose. The code includes two sodium combustion models (so called ‘spray combustion’ and ‘pool combustion’), a mass and heat transfer model considering a six-flux gas radiation and a coagulation and sedimentation model of sodium oxide and hydroxide aerosols. The sodium spray combustion rate is evaluated by a summation of the combustion rate of each sodium droplet with an individual diameter. A flame sheet model is applied to situations where sodium spreads out on the floor and a pool combustion takes place. The model assumes an infinitely thin flame above the pool surface and is based on a mass and energy balance in the flame. As the results of numerical analyses of a sodium spray combustion test, a location of high-temperature core region and a maximum temperature agrees with the experiment. Good agreements of an overall transient behavior are obtained in a large-scale sodium combustion test analysis. The numerical analyses also demonstrate that the distributions of temperature and chemical species concentration vary with sodium combustion modes. If sodium scatters and the spray combustion is dominant, the distributions vary in space. When a large amount of sodium exists on a floor and the pool area is enlarged, the distributions are more uniform in space.