KAGAKU KOGAKU RONBUNSHU
Online ISSN : 1349-9203
Print ISSN : 0386-216X
ISSN-L : 0386-216X
Volume 25 , Issue 2
Showing 1-38 articles out of 38 articles from the selected issue
  • SHINTARO FURUSAKI
    1999 Volume 25 Issue 2 Pages 131-135
    Published: March 10, 1999
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Production of useful secondary metabolites and regeneration of useful plants are attracting exten-sive interest from investigators of plant cell culture. In this short review, recent developments in the application of plant cell culture system are described referring to the works of the author's group. Regarding callus culture producing secondary metabolites, the following topics are described : 1. twostage culture, 2. conditioning effect, 3. kinetic structured model, 4. immobilization, and 5. reactors. Production of useful substances with hairy root culture is also effective and described in this review. Regeneration of plants contributes to production of food and to afforestation. Production of somatic embryos and artificial seeds is described as well.
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  • AYAAKI ISHIZAKI, GENTA KOBAYASHI, PHENJUN VONKTAVEESUK, TAKEHARU TSUGE ...
    1999 Volume 25 Issue 2 Pages 136-142
    Published: March 10, 1999
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    We have developed a high efficiency L-lactate fermentation process employing the homofermentative lactic acid bacterium, Lactococcus lactis IO-1 with a pH-dependent substrate feed system in order to consume the substrate completely and maintain high activity of cell growth, production, and substrate consumption. Furthermore a pH-dependent substrate feed system was combined with turbidity control consisting of a laser probe and micro filter module for cell-recycling. With this system, we achieve a high efficiency L-lactate continuous culture. We are able to construct high efficiency bioconversion systems from xylose to P (3 HB) via L-lactate and other organic acids because Lactococcus lactis IO-1 can utilize not only glucose but also xylose as a carbon source. Thus, we have developed a new substrate feed system which is able to automatically control substrate concentration in a broth. A new batch fermentative system for production of biodegradable plastic material, polyhydroxybutyrate [P (3 HB)] from culture broth of Lactococcus lactis IO-1 is vealized.
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  • HAJIME UNNO, XIN-HUI XING, YASUNORI TANJI
    1999 Volume 25 Issue 2 Pages 143-148
    Published: March 10, 1999
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    As the wastewater treatment process is directly related to the environmental process, its technology should be accepted to the public. Substances included in wastewater are so variable such as not only biological origin but also xenobiotic that their physical and chemical properties are very much complicated. Their biological treatment process is to utilize the versatile characteristics of microbes. Degradation pathway of a target chemical is generally composed of many enzymatic reactions so that one microbial species does not necessarily produce all enzymes for the reactions, which implies the necessity of constructing microbial consortium. During the startup of the biological wastewater treatment process the acclimatization process, which is considered to prepare microbes carrying plasmid encoding the necessary enzymes and also to construct microbial consortium, is needed. Taking the reception by the public into consideration, microbial preparation will not be done by a so-called artificial genetic manipulation but utilizing the gene transfer phenomena observed in the natural environment. In the present paper, by setting the above two views as a steering concept a composite microbial system consisting of porous carriers aiming at the simultaneous removal of carbonaceous and nitrogenous compounds, and a system for degrading a xenobiotic compound are examined. In addition, gene transfer which may appear in the wastewater treatment system is also discussed.
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  • MASAYUKI TANIGUCHI
    1999 Volume 25 Issue 2 Pages 149-157
    Published: March 10, 1999
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Co-culture systems containing two microorganisms for production of useful substances are described. The co-culture of Bifidobacterium longum and Propionibacterium freudenreichii, where lactic acid produced once from lactose by B. longum is converted to acetic and propionic acids by P. freudenreichii, was carried out. Through the sequential conversion of lactose using the two microorgan-isms, the culture supernatant containing a mixture of acetic and propionic acids without lactic acid is produced. The antimicrobial activity of the mixture is higher than that obtained in the cultivation of B. longum alone.
    We developed a novel co-culture system composed of two fermentors and two microfiltration modules for efficient ethanol production from a mixture of glucose and xylose by co-culture of Pichia stipitis and Saccharomyces cerevisiae. The proposed co-culture system allowed regulation of the dissolved oxygen concentration at a level suitable for an individual yeast in each fermentor, as well as the successful exchange of culture medium between two fermentors. When P. stipitis and S. cerevisiae are cultivated individually under different oxygen supply conditions in the new co-culture system, the yield and productivity of ethanol from a glucose and xylose mixture are higher than in single culture of P.stipitis alone.
    By clarifying the interactions among microorganisms, new bioprocesses in which similar performance to co-culture systems is expressed even using a single microorganism, are expected to be developed for improvement of biochemical reaction systems.
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  • SHIGEO KATOH, KENJI MURAO
    1999 Volume 25 Issue 2 Pages 158-162
    Published: March 10, 1999
    Released: November 12, 2009
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    In this review on preparation methods of specific affinity ligands for separation and detection, examples of fusion proteins containing affinity tags for specific separation and also of selection methods of monoclonal antibodies from combinatorial libraries are summarized. Advantages of anti-peptide antibodies for immunoaffinity separation of proteins are discussed. Anti-peptide antibodies against peptides in N-or C-terminal regions of target proteins adsorb native proteins, as well as antigen peptides, and the adsorbed proteins ere specifically eluted from the antibodies by the eluent containing the antigen peptides, under mild conditions.
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  • TAIZO HANAI, HIROYUKI HONDA, TAKESHI KOBAYASHI
    1999 Volume 25 Issue 2 Pages 163-168
    Published: March 10, 1999
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Simulation and control using a mathematical model are often difficult in the sake mashing process, because this process is a complicated process which involves many microorganisms and enzymes. Recently, knowledge information processings, such as fuzzy logic, artificial neural network (ANN), and genetic algorithm (GA), have been developed. These information processings have been applied to control sake mashing process. The fuzzy logic and fuzzy neural network with the extraction of toji's knowledge and experience about the temperature control of the sake mashing process were applied to the temperature control of experimental mashing. Time course data were similar to those from a conventional control based on the decision of the toji. ANN was applied to estimate enzyme activities in koji from the temperature and humidity orbits of koji making process. The suitable courses of temperature and humidity for koji production with the desired values of enzyme activities were determined by applying these models and GA.
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  • HISAO OHTAKE, TOSHIO TSUJI, HIROYUKI KURATA
    1999 Volume 25 Issue 2 Pages 169-176
    Published: March 10, 1999
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    To understand the elaborate system of a living organism, it is essential to know its “software”, as well as its “hardware”. The software of a living organism may be defined as the package of algorithms (methods and procedures) for its survival. The hardware of a living organism is encoded by genes on the chromosome. Its behaviors should be explainable on the basis of algorithms. The algorithms of a living system can be viewed as biological information that has been envolved over its long history of evolution. Among living organisms are bacteria that are probably the simplest systems for analyzing the software of living organisms. In the present paper, we describe our method for constructing a virtual bacterial system as a tool for analyzing the software of a living organism. We also describe bacterial algorithms for surviving during phosphate starvation and exhibiting an intelligent behavior called chemotaxis. In addition, we demonstrate a mobile robot whose behavior is controlled by a computer program designed on the basis of the bacterial chemotaxis algorithm.
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  • MASAYASU SUZUKI, TAKESHI KUMAGAI, YUUICHI NAKASHIMA
    1999 Volume 25 Issue 2 Pages 177-181
    Published: March 10, 1999
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    An on-line monitoring system for lactic acid fermentation is developed by using integrated micro enzyme sensors, a flow injection analysis system, and a micro dialysis system. The calibration curves ofmicro glucose, lactose and lactate sensors show good linearity in the concentration range below 70 mM By combination with the micro dialysis system, the enzyme sensors can measure the whole concentration range of lactic acid fermentation, and interference by the medium can not be observed.The on-line sensor system is then applied to lactic acid fermentation of Lactobacillus delbrueckii. The sensor systemcan monitor the glucose and lactate concentrations simultaneously during 24-h fermentation, and the measurements show good agreement with those of the conventional colorimetric method.
    The sensor system can also be applied to on-line monitoring of lactose and lactate during Lactobacillus lactis fermentation.
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  • AKIRA MATSUDA, KENJI KAWASAKI, SATOSHI TOMOSUGI
    1999 Volume 25 Issue 2 Pages 182-188
    Published: March 10, 1999
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    The batch aerobic digestion process is suitable for treating excess activated sludge collected from a small wastewater treatment plant. The effect of sludge concentration on treatment characteristics of the digestion process is investigated in this paper. Sample sludges are the excess activated sludges of a municipal wastewater treatment plant and the activated sludges acclimated to glucose and glucosepeptone, and these sludges are conditioned to four concentrations. In every concentration of each sludge, the final reduction ratio and the rate constant of decomposition of sludge solids are constant, and the decomposition rate could be related to the oxygen uptake rate based on the reaction model of aerobic digestion where the sludge composition formula is assumed as C5H7NO2. For the excess activated sludge and glucose-peptone acclimated sludge, organic nitrogen produced by aerobic digestion is transformed through NH4-N to NO3-N, pH decreases rapidly at the beginning of digestion, and the denitrification percentage is small. On the other hand, for glucose acclimated sludge, NO3-N is not detected and pH was between 7 and 8 during the first 1020 days, and the denitrification percentage increases. The sludge reduction ratio performed by anaerobic digestion in the municipal wastewater treatment plant could be attained in half the time by aerobic digestion, and the organic carbon concentration of supernatant in aerobic digestion is much smaller than that of anaerobic digestion.
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  • ATSUSHI HASHIMOTO, TAKAHARU KAMEOKA, YASUHIKO SHIINOKI, KENSUKE ITO
    1999 Volume 25 Issue 2 Pages 189-194
    Published: March 10, 1999
    Released: February 19, 2010
    JOURNALS FREE ACCESS
    We propose a new method to suppress cell metabolism by dissolving hydrophobic gas into intracellular water, and structuring it under hydrophobic-gas pressure. Xenon, krypton, argon, and helium gases show death inhibitory effects on all test bacteria (Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis, Staphylococcus aureus and Streptococcus salivarius) suspended in physiological saline with no nutrient component during storage under the conditions. In addition, different death inhibitory effects are observed among the five test bacteria, and this proposed method is more effective for gram-negative bacteria with thin cell walls than for gram-positive bacteria with thick cell walls. Further, xenon gas exhibit more significant effects for death inhibition than any other test gases, and the optimum initial partial pressure to inhibit the death is observed only for xenon gas in the present experimental conditions. Consequently, it is experimentally suggested that the cell metabolism can be suppressed almost perfectly by making the optimum water structure.
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  • KOUICHI GOTO, ATSUSHI MIKI, RYUICHI UEOKA
    1999 Volume 25 Issue 2 Pages 195-199
    Published: March 10, 1999
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    It is noted that the diastereoselective specificity for the hydrolysis of dipeptide esters having phenylalanine (Phe) or leucine (Leu) residues in aqueous solution systems should correcpond to the concentration of substrates and reaction temperature. In particular, the markedly high diastereoselectivity is observed for the hydrolysis of p-methoxycarbonylphenyl N- (benzyloxycarbonyl) -D (L) -phenylalanyl-L-phenylalaninate (Z-D (L) -Phe-L-Phe-PMCP), and the diastereoselectivity is maximized by regulating the concentration of substrates and reaction temperature. On the other hand, such a diastereospecificity is not observed for the hydrolysis of p-methoxycarbonylphenyl N- (benzyloxycarbonyl) -D (L) -leucyl-L-leucinate (Z-D (L) -Leu-L-Leu-PMCP). The spectroscopic study suggests that the high diastereoselectivity for the spontaneous hydrolysis of Z-D (L) -Phe-L-Phe-PMCP is originated mainly from the monomer-aggregates transition of diastereomeric esters in aqueous solution systems.
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  • EIKO MURAYAMA-KAYANO, NAOHITO ABE, TERUYUKI NAGAMUN
    1999 Volume 25 Issue 2 Pages 200-205
    Published: March 10, 1999
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    The Random Amplified Polymorphic DNA (RAPD) technique is a useful method to detect genetic polymorphisms. Since pattern recognition of the RAPD is usually based on eye measurement, the result is often unreliable. To overcome this human error, we have developed a computer-aided method using image processing and pattern recognition by a neural network model to identify RAPD patterns derived from bacterial species.
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  • YOSHIHIKO MURAKAMI, TAKAYA ODA, KAZUYUKI CHIBA, AKIRA HIRATA
    1999 Volume 25 Issue 2 Pages 206-213
    Published: March 10, 1999
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Lysosomotropic detergents (cytotoxic compounds designed as anticancer agents) acylated with Z-GlyPhe (N-benzyloxycarbonyl-L-glycyl-L-phenlylalanine, masking into cells), are facilitated entry into the target cells. In this study, the precursor of Z-GlyPhe, namely Z-GlyPheOMe (N-benzyloxycarbonyl-L-glycyl-L-phenlylalanine methyl ester), is enzymatically synthesized continuously utilizing an extractive reaction. The yield of Z-GlyPheOMe is usually ca. 10 % in aqueous medium due to the unfavorable shift of the chemical equilibrium towards a peptide bond hydrolysis. Since this peptide precursor is non-ionic, the precursor was distributed to an organic phase in an aqueous/organic biphasic system. Z-GlyPheOMe is selectively extracted into the organic phase simultaneously with an enzymatic synthesis in an aqueous enzyme solution in an aqueous/organic biphasic system, and ca. 100 % yield of Z-GlyPheOMe is achieved.
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  • HITOSHI FUNAHASHI, YUKITAKA NISHIYAMA, MASAKI ASANO, KATSUMI NAKAO
    1999 Volume 25 Issue 2 Pages 214-219
    Published: March 10, 1999
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Chlorella sp., which has been used for industrial biomass production, was cultured under a heterotrophic condition. When pH was kept at 6.0 during the initial period of the culture, corresponding to logarithmic growth of cell, and thereafter shifted to 8.0, the instantaneous specific production rates of chlorophyll (CHL) throughout the culture were maintained at relatively high values. This pH shift pattern was proposed as the optimum one. The maximum CHL content under the optimum pH shift, however, was only 1.28 W/W % at the agitation speed of 600 r.p.m.. On the other hand, low agitation speeds less than 300 r.p.m. were more favorable for CHL biosynthesis. The maximum CHL content reached 3.1 W/W % at the agitation speed of 250 r.p.m.. This value was about 2.4 times higher than that in the case of 600 r.p.m.. It was suggested that the effect of agitation speed on CHL biosynthesis depended on the existence of a period lacking oxygen supply. Though the maximum CHL content reached also about 3 W/W % under the constant pH value of 6.0 at agitation speed of 250 r.p.m., the specific production rate of CHL during the middle period of the culture was 0.54 × 10 kg/ (kg dry cell·h), and about 70 % of that in the case of the optimum pH shift. This result revealed that CHL biosynthesis in the heterotrophic culture of Chlorella sp. was carried out more efficiently under both the optimum pH shift and the agitation speed of 250 r.p.m..
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  • DAISUKE TOMINAGA, MASAHIRO OKAMOTO
    1999 Volume 25 Issue 2 Pages 220-225
    Published: March 10, 1999
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Organizationally complex nonlinear systems, such as metabolic pathways and gene-circuit systems, are comprised of numerous, richly interacting system components. In the case where the details of the process that govern interactions among system components (state variables) are not well known, however, how do we represent mathematical model for such complex nonlinear processes ? Estimation of the interaction mechanism among system components by using the experimentally observed dynamic responses (time-courses) of some of the system components is generally a so-called “inverse problem.” The “S-system, ” which belongs to power-law formalism, is one of the best representations to solve this inverse problem ; the S-system is rich enough in structure to capture all relevant dynamics. This formalism has, however, a major disadvantage in that it includes large number of parameters to be estimated ; the estimation of these parameter-values is almost never straightforward, and almost always a real challenge. In this paper, for the purpose of solving the inverse problem, we introduce the Genetic Algorithm and propose an efficient procedure for estimation (optimization) of large numbers of parameters in S-system formalism.
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  • SHOKO TSUJIMOTO, HUIDONG SHI, KAZUYUKI SHIMIZU, KAZUHIRO MAE, KOICHI M ...
    1999 Volume 25 Issue 2 Pages 226-232
    Published: March 10, 1999
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Fermentation characteristics are investigated for the conversion of glycolate, acetate, formate, and malonate obtained by the oxidation of low-rank coals to poly (β-hydroxybutyrate) (PHB) using A. eutrophus cells. Based on the cultivation experiments using one of the organic acids as a sole carbon source, it is found that acetate is the most effectively converted to PHB. When mixed organic acids are used, formate is preferentially consumed, followed by acetate, and finally glycolate.
    Although malate can not be utilized, it is implied that it might change the pathway flux distributions based on the metabolic flux analysis. Namely, it shows competitive inhibition to succinate dehydrogenase so that its addition during fermentation results in flux reduction from succinate to maleic acid as well as glyoxylate flux and gluconeogenesis flux. It is also found that NADPH generated from isocitrate is preferentially utilized for the reaction from α-ketoglutarate to glutamate when NH3 concentration is high, while it is eventually used for the PHB production from acetoacetyl CoA as NH 3 concentration decreases.
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  • HIDENORI ONO, YUKA KIDA, HIROMI ONOMICHI, KENICHI MURAOKA, KAKUJI TOJO
    1999 Volume 25 Issue 2 Pages 233-236
    Published: March 10, 1999
    Released: February 19, 2010
    JOURNALS FREE ACCESS
    We have developed a novel transdermal therapeutic system (TTS) which controls the time-lag for drug absorption through the skin. The diffusion coefficient in the ethylene-vinylacetate (VA) copolymer (EVA) used as a time-lag controlling membrane of a model drug, isosorbide dinitrate (ISDN), is found to be independent of the VA fraction in the EVA membrane. The steady state flux of ISDN through the membrane is unchanged by controlling the fraction of the VA content in the EVA membrane. The in vitro skin permeation experiment shows that the time-lag for drug absorption through the skin can be controlled within the range of 5 to 14 hours. The in vivo skin permeation experiment with repeated application of the device shows that the TTS developed can provide a blood level lower than the therapeutic concentration 6 to 12 hours after the onset of the delivery system. The timed control of blood level obtained in this system is useful to minimize side effects as well as drug tolerance.
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  • HIDEKI NAKAYA, OSATO MIYAWAKI, KOZO NAKAMURA
    1999 Volume 25 Issue 2 Pages 237-239
    Published: March 10, 1999
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Solubilities of behenic acid (BA) and ethylbehenate (EB) in supercritical carbon dioxide (SCCO2) are measured by a flow-type apparatus at 313 K from 12.3 to 22.1 MPa. The solubilities measured and their pressure dependence are analyzed by regular solution theory combined with the Flory-Huggins theory. The solubility of BA is very different from that by Chrastil, especially in the low pressure range. The solubility of EB is about 1, 000 times higher than that of BA. The higher solubility of fatty acid ethyl ester as compared with fatty acid seems effective to avoid solubility limitation of substrates in enzymatic reactions in SCCO2.
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  • YOSHIHIKO MURAKAMI, HIDETAKA KAWAKITA, AKIRA HIRATA
    1999 Volume 25 Issue 2 Pages 240-243
    Published: March 10, 1999
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    A novel method for peptide synthesis in an aqueous/organic biphasic system utilizing an surfactant-coated enzyme catalytically active in organic media is proposed. In this method, peptides synthesized in an organic phase are selectively extracted to an aqueous phase. We apply this method to α-chymotrypsin-catalyzed synthesis of kyotorphin (anodyne peptide) precursor (Z-TyrArgOEt), and 30 % yield of peptide is achieved (ca. 20 % in aqueous system).
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  • YOSHIHIKO MURAKAMI, AKIRA HIRATA
    1999 Volume 25 Issue 2 Pages 244-247
    Published: March 10, 1999
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    A process for enzymatic hydrolysis of proteins to synthesize biologically active peptides in an aqueous two-phase system is proposed. We apply this method to the enzymatic hydrolysis of zein (corn protein, Zea mays L.) Zein and its enzymatic hydrolysates distribute to PEG-and DEX-rich phases, respectively, in an aqueous PEG/DEX two-phase system. The angiotensin I converting enzyme (ACE) inhibitory peptides are recovered in a DEX rich phase.
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  • NORIO MIURA, MASAO IMAEDA, KYOUJI HASHIMOTO, R. K. WOOD, HIROFUMI HATT ...
    1999 Volume 25 Issue 2 Pages 248-252
    Published: March 10, 1999
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    PVC reactor is a typical chemical process which has complex system with unknown dynamics. It is well known that this plant is controlled by PID control. The PID controller is well understood and accepted among operators and engineers due to its intuitive simplicity. However, it is seen difficult to find useful PID gains for complex systems. On the other hand, many control techniques have been proposed in order to improve controlled performances for this plant. Since these techniques are too complex, they may be difficult to apply to actual plants.
    In this paper, we propose GPC method which has PID control structures. Here, this design method includes the constrained parameter tuning method to assure positive PID gain. Also, we define and design operating parameters which influences controlled performance. Finally, we show the simulation results of PVC system that is controlled with PID gains obtained by GPC algorithm.
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  • KAZUTAKA TAKATA, HISAYOSHI ITO, MASAHIKO KIKUCHI, YUKIMICHI OKAMOTO
    1999 Volume 25 Issue 2 Pages 253-258
    Published: March 10, 1999
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Flow structure and mixing characteristics in a stirred tank with dual wide paddle impeller were examined using computational fluid dynamics (CFD) CFD was conducted using analysis code for fluid flow, and velocity measured by laser doppler velocimeter, power consumption and mixing time were used for evaluating computed results.
    The computed flow field and power consumption agreed well with themeasured values within 5% deviations. Although mixing time had a slight discrepancy between computed and measured ones, its mixing process well agreed with the observations. Since the computed flow pattern and mixing process agreed well with the measured values, computed results are useful for evaluating complex flow field in a stirred tank. A detailed investigation using computed results shows that dual cross-installed wide paddle impellers lead to superior mixing performance in the stirred tank, and pressure gradient between upper and lower paddles is found to be the factor that promotes fluid transport in the tank, which is never the case when the dual wide paddles are installed in the same plane.
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  • YOSHITADA TOMOYASU, FUMIO YOSHINO, HIROSI IWATA, HIROMITSU KAWAZOE
    1999 Volume 25 Issue 2 Pages 259-265
    Published: March 10, 1999
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    The flow characteristics of granular materials and gas in a vertical packed moving bed, called a “stand pipe”, furnished at the bottom of the fluidized bed are investigated theoretically and experimentally.
    A correlation equation of axial stress σz and voidage ε of granular materials in the stand pipe is proposed through investigations of the continuity equation, the momentum balance equation, Ergun's equation for gas pressure loss and the gas pressure distribution data measured experimentally in the axial direction.
    Regarding the relation of the axial stress and the voidage, it was recogniged that :
    1. The absolute value of dσz/ dε is large at the voidage near the minimum fluidizing condition, and at the voidage in the dense packed condition, and an inflection point of az exists in range between the both conditions ;
    2. It seems to be the wall-friction-effect of stand pipe that the absolute value of dσz/dε is larger at the inlet of stand pipe, and ;
    3. The stress is also a function of the particle diameter.
    The gas flow rate, axial stress distribution of granular materials, gas pressure distribution and voidage distribution in the axial direction of the stand pipe can be calculated from relating equations.
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  • SHINJI YASUI, TADASHI AMAKAWA
    1999 Volume 25 Issue 2 Pages 266-271
    Published: March 10, 1999
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    In order to develop a treatment of low-level radioactive miscellaneous solid waste containing combustibles by plasma melting technology, the incineration of polyethylene (PE), the main combustible in the wastes, is examined by using a 100 kW plasma melting system. The overall reaction rate of PE in the plasma furnace is examined by changing the air flow rate, the feeding weight of PE, and the shape of PE. The reaction rate is found to be independent of air flow rate, and the shape of PE. The reaction rate is thus a function solely of weight of PE fed, and can be used to estimate the residence time of PE with a given weight required for complete incineration.
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  • KENJI OZAKI
    1999 Volume 25 Issue 2 Pages 272-281
    Published: March 10, 1999
    Released: November 12, 2009
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    This paper presents a model of the raw material homogenizing and mixing process in a cement plant as a multivariable stochastic system, and moreover proposes application of the extended horizon adaptive control (EHAC) with a static pre-compensator matrix with fixed parameters. The regulation and tracking performances of the hydraulic modulus (HM), silica modulus (SM), and iron modulus (IM) by the proposed control system are compared with the actually applied classical control method which is PI control with Smith compensators.
    The robustness performances of the extended horizon adaptive mixing control system are compared with the classical control, and also with a stochastic model reference adaptive control based on a one step prediction method, especially for changes of process dynamics including the dead time. The simulation results show that the proposed EHAC system has suitable performances.
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  • TSUGUHIKO NAKAGAWA, NORIO ARAI
    1999 Volume 25 Issue 2 Pages 282-289
    Published: March 10, 1999
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    The authors have developed a non-oxidizing heater system, which can heat up materials such as steel to over 1, 273 K under a perfect non-oxidizing atmosphere by the convection heat transfer of a high temperature N2 gas jet stream. This system, an N2 jet heater, can heat N2 gas up to 1, 773 K, and can continuously supply the high temperature N2 gas using a pair of heaters installed with a regenerative heat exchanger inside the combusion chamber. In this system, the heat of combustion of the fuel can be transfered to the sensible heat of fresh N2 gas at a thermal efficiency of almost 100%. This system has been applied to the tundish heater of a real continuous caster. As a result, the rate of occurence of surface defects in the quality of steel products is reduced to less than one-fifth of the past level. This paper discusses the mechanism of heat transfer by the high temperature N2 gas jet stream, presents an outline of the heater system, and describes the effect of its use on steel product quality.
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  • SHINOBU KODA, KENJI ENDO, YOSHIHIRO KOJIMA, HIROYASU NOMURA
    1999 Volume 25 Issue 2 Pages 290-293
    Published: March 10, 1999
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Sonication was carried out under atmosphere of air, oxygen, nitrogen, argon, or their gas mixtures. The value of pH in water for different dissolved gases was obtained under a constant ultrasonic intensity. The ultrasonic intensity in the reaction vessel was measured by use of the decomposition reaction of porphyrin in water. Under an air atmosphere, the pH value changed from 7 to 4.3 for an irradiation time of 30 min and after that the pH value approached to 3.7. On the other hand, the pH values for water saturated with Ar, N2 or O2 slightly decreased. In the mixture of Ar, N2 and O2, the minimum pH in water saturated with the Ar + O2 mixture was observed around 60 % of Ar, and that saturated with the Ar + (N2 and O2) mixture at around 30 % of Ar. The amount of OH radical produced on sonication was consistent with that estimated from products obtained by decomposition of water. From these results, it is concluded that the decrease of pH is influenced not only by N2, but also by O2.
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  • YOSHIRO INOUE, YUSHI HIRATA
    1999 Volume 25 Issue 2 Pages 294-302
    Published: March 10, 1999
    Released: November 12, 2009
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    The elementary mechanism of laminar mixing is analyzed with numerical simulation from the point of view of nonlinear dynamical theory. The analyzed flow is a time-periodic cellular convection in the two dimensional plane system. The effect of molecular diffusion is neglected in order to investigate the mechanism of mixing performed only by convection. The mixing processes can be classified into three steps. In the initial stage, the mixing pattern and the fluid exchange between the cells are determined by the geometric shapes of the lobes, which are composed of stable manifolds and unstable manifolds near the cell boundaries. In the next stage, the chaotic motion of fluid plays an important role in the construction of the fine structure in the lobes. The mixing pattern in the final stage is controlled by the geometric shape of the outermost KAM curves in the cells.
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  • TADAATSU IDO, SEIJI MIZUNO, TOMOTAKA YOSIMORI, MIKIO MORI, SHIGEO GOTO
    1999 Volume 25 Issue 2 Pages 303-308
    Published: March 10, 1999
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Reactions of graphite, activated carbon and lignin with carbon dioxide are carried out at 973 K by using alkali metal carbonates (m.p.8911, 164 K) and eutectic mixtures of these compounds (m.p. 669787 K) as catalysts.
    The reaction occurrs by mixing catalyst with graphite physically when the melting points of the catalysts are lower than the reaction temperature. The gasification rates of graphite and activated carbon by this physical mixing method are almost the same as those of the impregnation method of the catalyst. However, the reaction with catalyst using the physical mixing method did not proceed when the melting points of the catalysts are higher than the reaction temperature.
    Repeated use of the molten catalyst is also studied to investigate the possibility of continuous gasification of carboneous materials. After the activated carbon (or lignin) is consumed in a batch reactor, the same amount is added in the reactor containing the catalyst and the reaction starts again. It is found that the eutectic molten catalyst can be reused without any loss of catalytic activity by repeating this operation.
    Furthermore, the co-existing effect of molten catalyst with Ni catalyst is investigated. The reaction rate at 773 K in the case of co-existing these catalysts is 4.3 times of Ni catalyst.
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  • OSAMU MIYATAKE, KOTARO TAGAWA
    1999 Volume 25 Issue 2 Pages 309-315
    Published: March 10, 1999
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    To complement the authors' previous numerical analysis for a RO seawater desalination system utilizing the static pressure due to the depth of the sea, a numerical analysis is performed for a RO brackish water desalination system utilizing the static pressure head of brackish water in a vertical pit, by taking into consideration the solute permeation through membrane.
    Numerical results are obtained for the effects of the length of channel, the submerged depth of device, the pure water permeability of membrane, the solute permeability of membrane, and the Schmidt number of brackish water on the axial variation of velocity, concentration, and pressure in laminar natural convection flow of brackish water, caused by the concentration difference in the moderately narrow annular channel formed between a tube-type membrane and a cylindrical rod. The effects on the axial variation of the velocity of transmitting fresh water and the concentration of transmitted fresh water are also examined.
    From the results, it is shown quantitatively that the application of large submerged depth of device and the adoption of high pure water permeability of membrane bring about a increase in the flow rate of fresh water with low solute concentration.
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  • AKIRA NINOMIYA, MISUZU SATO, HIROYASU NISHIGUCHI, TATSUMI ISHIHARA, YU ...
    1999 Volume 25 Issue 2 Pages 316-321
    Published: March 10, 1999
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    In order to develop a novel production process for substitute natural gas (SNG), SiO2-supported metal catalysts effective for methane formation from propane and butanes are investigated under atmospheric pressure. Two reactions, namely, methane formation, C3H8→ 2 CH4+C, and decomposition, C3H8→ 3 C + 4 H2, took place over the analyzed metal supported catalysts. The highest activity is measured for Ni/SiO2, revealing 100 % conversion and over 90 % selectivity for methanation at 500° C. As far as the activities of other metal supports are concerned, the order is found to be Ni>>Co > Fe> Pt> Pd. Butanes show 9599 % conversion and 80 % selectivity over Ni/SiO2 at 500°C. Adopting the condition of less than 2, 700 h-1 is found suitable for selective CH4 formation. Supplying the feed of C3H8/H2=0.5, only hydrogenolysis of propane takes place over Ni/SiO2 above 250°C, and the conversionreachs 90% and 100% at 350°C and 500°C, respectively.
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  • NOBUSUKE KOBAYASHI, RYOHEI YAMAZAKI, SHIGEKATSU MORI
    1999 Volume 25 Issue 2 Pages 322-330
    Published: March 10, 1999
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    A model for predicting solid mixing in two dimensional bubbling fluidized beds is proposed. Assuming that diffusional mixing induced by bubble motion is superimposed on the convective or circulative mixing originating from bubble distribution, a diffusion equation is solved numerically with the values of two parameters, the solid circulation rate and the dispersion coefficient, properly estimated. The comparison between calculated and observed values of solid concentration reveals that this model is applicable to simulate solid mixing in bubbling fluidized beds.
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  • TOSHIHIRO AOKI, TADAFUMI ADSCHIRI, KUNIO ARAI
    1999 Volume 25 Issue 2 Pages 331-337
    Published: March 10, 1999
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    This paper presents a method to evaluate kinetics for an immobilized enzyme with nonuniform activity distribution. Kinetic studies were conducted for esterification of caproic acid with methanol by immobilized lipase (Lypozyme) at 40°C. Effective diffusivity (De) and Michaelis constant (Km) were determined independently and then the activity distribution was determined by analysing the relationship between the reaction rate and the substrate concentration. First De was determined by step response experiments that were conducted in a packed-bed column using carbonic acid as a tracer and hexane as a solvent. In the analysis of the response curves, intraparticle mass transfer, De, and adsorption of tracer in the particles was taken into account. The adsorption constant, Ka, was evaluated by adsorption experiments. Then, Km was determined by analysing the relationship between the reaction rate and the substrate concentration under chemical reaction control. The final step was the evaluation of active enzyme distribution in the particles using De, Km and Ka. The enzyme activity was observed only in the vicinity of the surface of the support. By using these evaluated constants and considering the nonuniform activity distribution of the immobilized enzyme, kinetics of the reaction could be successfully described over a wide range of concentrations and particle sizes.
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  • KATSUMI TOCHIGI, TATUHIRO GOTOU, KENTAROU AKIMOTO, KAZUO KOJIMA
    1999 Volume 25 Issue 2 Pages 338-342
    Published: March 10, 1999
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    In order to investigate the use of toluene for separating phenol in aqueous phenol solution, the liquid-liquid equilibria for the ternary phenol + water + toluene system and constituent binary phenol + water and water + toluene systems are measured between 298.15 and 343.15 K. The distribution coefficients of phenol become larger as the temperature becomes low. The extraction ability of toluene is considered to be similar to that of benzene used in Podobielniak dephenolizing equipment. The ternary liquid-liquid equilibria predicted by the SILS equation using binary parameters agree with the observed ones for three components within the absolute arithmetic absolute deviations of 0.014 mole fraction.
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  • 1999 Volume 25 Issue 2 Pages e1a
    Published: 1999
    Released: February 19, 2010
    JOURNALS FREE ACCESS
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  • 1999 Volume 25 Issue 2 Pages e1b
    Published: 1999
    Released: February 19, 2010
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  • 1999 Volume 25 Issue 2 Pages e1c
    Published: 1999
    Released: February 19, 2010
    JOURNALS FREE ACCESS
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  • 1999 Volume 25 Issue 2 Pages e1d
    Published: 1999
    Released: February 19, 2010
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