Showing papers by "Oita University published in 1998"
TL;DR: In this paper, the stability of perovskite oxides was investigated in Solid Oxide Fuel Cells (SOFCs) and the power density was found to be very stable in reducing, oxidizing and atmospheres.
Abstract: ‐based perovskite oxides doped with Sr and Mg exhibit high ionic conductivity over a wide range of oxygen partial pressure. In this study, the stability of ‐based oxide was investigated. The ‐based oxide was found to be very stable in reducing, oxidizing, and atmospheres. Solid oxide fuel cells (SOFCs) using ‐based perovskite‐type oxide as the electrolyte were studied for use in intermediate‐temperature SOFCs. The power‐generation characteristics of cells were strongly affected by the electrodes. Both Ni and (Ln:rare earth) were suitable for use as anode and cathode, respectively. Rare‐earth cations in the Ln site of the Co‐based perovskite cathode also had a significant effect on the power‐generation characteristics. In particular, a high power density could be attained in the temperature range 973–1273 K by using a doped for the cathode. Among the examined alkaline earth cations, Sr‐doped exhibits the smallest cathodic overpotential resulting in the highest power density. The electrical conductivity of increased with increasing Sr doped into the Sm site and attained a maximum at . The cathodic overpotential and internal resistance of the cell exhibited almost the opposite dependence on the amount of doped Sr. Consequently, the power density of the cell was a maximum when was used as the cathode. For this cell, the maximum power density was as high as 0.58 W/cm2 at 1073 K, even though a 0.5 mm thick electrolyte was used. This study revealed that a ‐based oxide for electrolyte and a ‐based oxide for the cathode are promising components for SOFCs operating at intermediate temperature.
260 citations
TL;DR: In this paper, powder neutron diffraction data have been collected between room temperature and 1000°C for the oxide ion conductor La0.9Sr0.1Ga0.8Mg0.2O2.
133 citations
TL;DR: Other properties of the strain, such as the formation of endospores, the presence of meso-diaminopimelic acid in the cell wall, the percent G+C of DNA, and the partial 16S ribosomal DNA sequence indicated that strain MH-1 should belong to the genus Bacillus.
Abstract: A thermophilic and actinic bacterium strain, MH-1, which produced three different endochitinases in its culture fluid was isolated from chitin-containing compost. The microorganism did not grow in any of the usual media for actinomyces but only in colloidal chitin supplemented with yeast extract and (2, 6-O-dimethyl)-beta-cyclodextrin. Compost extract enhanced its growth. In spite of the formation of branched mycelia, other properties of the strain, such as the formation of endospores, the presence of meso-diaminopimelic acid in the cell wall, the percent G+C of DNA (55%), and the partial 16S ribosomal DNA sequence, indicated that strain MH-1 should belong to the genus Bacillus. Three isoforms of endochitinase (L, M, and S) were purified to homogeneity and characterized from Bacillus sp. strain MH-1. They had different molecular masses (71, 62, and 53 kDa), pIs (5.3, 4.8, and 4.7), and N-terminal amino acid sequences. Chitinases L, M, and S showed relatively high temperature optima (75, 65, and 75 degreesC) and stabilities and showed pH optima in an acidic range (pH 6.5, 5.5, and 5.5, respectively). When reacted with acetylchitohexaose [(GlcNAc)6], chitinases L and S produced (GlcNAc)2 at the highest rate while chitinase M produced (GlcNAc)3 at the highest rate. None of the three chitinases hydrolyzed (GlcNAc)2. Chitinase L produced (GlcNAc)2 and (GlcNAc)3 in most abundance from 66 and 11% partially acetylated chitosan. The p-nitrophenol (pNP)-releasing activity of chitinase L was highest toward pNP-(GlcNAc)2, and those of chitinases M and S were highest toward pNP-(GlcNAc)3. All three enzymes were inert to pNP-GlcNAc. AgCl, HgCl2, and (GlcNAc)2 inhibited the activities of all three enzymes, while MnCl2 and CaCl2 slightly activated all of the enzymes.
132 citations
TL;DR: In this paper, the authors investigated the CO2 sensing properties of self-assembled multibilayer films as a molecular template and showed that they can be used as capacitive type CO2 sensors.
Abstract: Preparation of CuO thin films by decomposition of self-assembled multibilayer films as a molecular template was investigated. Furthermore, the CO2 sensing property of the resultant CuO thin films on a porous BaTiO3 was investigated as a capacitive type sensor. Self-assembled bilayer films of a few 1000 layers thickness can be readily obtained by casting an aqueous suspension composed of dimethyldihexadecylammoniun bromide (DC1–16), Cu(CH3CO2)2 , hexadecylethylenediamine and poly(vinyl alcohol). Divalent copper ions (Cu2+) which are associated with two hexadecylethylenediamine molecules were arranged in the hydrophobic layer of the multibilayer film. Rapid heating to the combustion temperature of DC1–16 was desirable for removing organic molecules in the multibilayer template. Thin films of CuO can be obtained by calcination at temperatures higher than 573 K. The resultant CuO thin films were porous and consisted of fine particles. The capacitance of CuO thin films prepared from self-assembled multibilayer films as a molecular template on the BaTiO3 porous substrate exhibited a high sensitivity to CO2 , which is twice that of a conventional mixed oxide capacitor of CuO–BaTiO3 . The capacitance of CuO thin films on BaTiO3 increases with increasing CO2 concentration in the range from 100 ppm to 50% at 873 K. Consequently, it is concluded that CuO thin films on BaTiO3 were appropriate capacitive type CO2 sensors.
114 citations
TL;DR: In this article, the authors investigated the characteristics of pulsed corona discharge in relation with flue gas cleaning, evaluation of high voltage power supply; design of plasma reactor; experimental study on DeNOx and DeSO2; decomposition of VOCs and indoor air cleaning.
98 citations
TL;DR: In this paper, the effects of doping certain transition metal cations for the Ga site on the oxide ion conductivity of La 0.8 Sr 0.2 Ga 0.5 Co 0.085 O 3 was investigated in detail.
94 citations
TL;DR: In this paper, the authors examined the circadian variation in the signal averaged electrocardiogram (saECG) and heart rate variability and investigate their relations in healthy subjects. But, their results were limited to a single cosinor method.
Abstract: Objective To examine the circadian variation in the signal averaged electrocardiogram (saECG) and heart rate variability and investigate their relations in healthy subjects. Methods 24 hour ECGs were obtained with a three channel recorder using bipolar X, Y, and Z leads in 20 healthy subjects. The following variables were determined hourly: heart rate, filtered QRS (f-QRS) duration, low and high frequency components of heart rate variability (LF and HF), and the LF/HF ratio. Results Heart rate, f-QRS duration, HF, and the LF/HF ratio showed significant circadian rhythms, as determined by the single cosinor method. Heart rate and the LF/HF ratio increased during daytime, and f-QRS duration and HF increased at night. f-QRS duration was negatively correlated with heart rate ( r = 0.95, p r = 0.94, p r = 0.93, p Conclusions f-QRS duration has a significant circadian rhythm in healthy subjects and is closely related to the circadian rhythm of autonomic tone.
91 citations
TL;DR: Among various rare earth phosphates, CePO4 and LaPO4 were found to catalyze the oxidative dehydrogenation of iso-butane to isobutene at 450-550°C using a feed gas of 75-mol% isobutane and 5 −mol% O2.
Abstract: Among various rare earth phosphates, CePO4 and LaPO4 were found to catalyze the oxidative dehydrogenation of iso-butane to iso-butene at 450–550°C using a feed gas of 75 mol% iso-butane and 5 mol% O2. As for the phosphates of Y, Pr, Nd, Gd, Er, and Yb, iso-butene was formed with a limited selectivity of 20–40% selectivity, and C3H6 formation and deep oxidation into CO and CO2 were promoted over the same temperature range. Temperature-programmed-desorption spectra of NH3 for CePO4 and LaPO4 consisted of two large desorption peaks with maxima at 100°C and 270°C suggesting that these phosphates have strong acid sites. But the rest of the phosphates have only weak acid sites. Rare earth phosphates have no adsorbed oxygen which can be desorbed up to 550°C. The lattice oxygen of CePO4 and PrPO4 can be reduced at 200°C and that of the rest of the phosphates at about 400°C. The amount of oxygen removed up to 550°C in TPR was smaller than the amount corresponding to a monolayer for all phosphates. Oxygen isotope equilibration experiments over CePO4 and LaPO4 revealed that only surface lattice oxygen can participate in the equilibration at 500°C and 550°C. It can be concluded that acidic character is a key factor in the selective oxidative dehydrogenation of iso-butane over the rare earth phosphate catalysts.
82 citations
TL;DR: In this article, the current status of capacitive type gas sensor was reviewed, and the results showed that CO2 concentration in office can be successfully monitored by the developed capacitive-type CO2 sensor.
Abstract: Current status of capacitive type gas sensor were reviewed in this paper. Although the number of publications on capacitive type sensors has been limited so far, capacitive type sensors have good prospects given that the capacitor structure is so simple enabling miniaturization and achieving high reliability and low cost. Among the reported capacitive type sensors, detection of gas based on a change in dielectric layer thickness is most promising. On this point of view, capacitive type CO2 and NO sensors using depletion layer formed at p-n junction of oxide semiconductor were introduced in detail. In addition, commercial capacitive type sensors for monitoring CO2 based on this principle were mentioned. CO2 concentration in office can be successfully monitored by the developed capacitive type CO2 sensor.
78 citations
TL;DR: Isotopic exchange was used to determine the oxygen tracer diffusion coefficient and surface exchange coefficient of LaGaO 3 based perovskites at a temperature from 923 to 1173 K.
78 citations
TL;DR: It is indicated that brain HA modulates satiation through both the VMH and masticatory function as well as due to the action of the Me.
Abstract: Both the ventromedial hypothalamus (VMH) and the mesencephalic trigeminal sensory nucleus (Me5) are densely innervated by histaminergic neurons. The depletion of neuronal histamine (HA) from the Me5 by the bilateral microinfusion of 448 nmol/rat alpha-fluoromethylhistidine (FMH), a specific suicide inhibitor of histidine decarboxylase, reduced the eating speed and prolonged meal duration, while leaving the meal size unaffected. HA depletion from the VMH increased the size of the meal and prolonged its duration, but not the eating speed. When the HA turnover rate was measured at 15 min after the scheduled feeding following fasting for less than 24 hr, the rate increased in the region including the Me5, but not in the hypothalamus. The turnover rate reached higher levels at 60 min in both regions. Gastric intubation of an isocaloric liquid diet or an equivolume of water with the liquid diet abolished the increase in HA turnover both in the Me5 region and the hypothalamus. The present findings indicate that brain HA thus modulates satiation through both the VMH and masticatory function as well as due to the action of the Me5. The HA function activated by mastication began earlier in the Me5 and later in the hypothalamus due to a signal originating from the oral proprioceptors and initiated by chewing.
TL;DR: In this paper, high-resolution powder neutron diffraction was used to show that the room temperature structure of the fast oxide ion conducting solid electrolyte La 0.9 Sr 0.1 Ga 0.8 Mg 0.2 O 2.85 is monoclinic, rather than orthorhombic, as for the undoped parent phase LaGaO 3.
TL;DR: Two copper(II) complexes with N,N'-bis(2-substituted-imidazol-4-ylmethylidene)-1,4-diaminobutane (2- substituent = H, 1; Me, 2) were synthesized, and their deprotonation assembly behavior was studied.
Abstract: Two copper(II) complexes with N,N'-bis(2-substituted-imidazol-4-ylmethylidene)-1,4-diaminobutane (2-substituent = H, 1; Me, 2) were synthesized, and their deprotonation assembly behavior was studied. X-ray analyses of 1 and 2 revealed that the molecules assume a butterfly shape bent by a line of N(2)-Cu-N(4) where the angle of N(3)-Cu-N(5) representing the extent of the molecular bend is 150.9(2) degrees and 105.66(8) degrees for 1 and 2, respectively. Due to the molecular bend, two imidazole moieties (sites A and B) are recognized as two inequivalent groups for the deprotonation process in which the imidazole group of site A is in an equatorial CuN(3) plane, while that of site B is in a CuN(2) plane bent from the equatorial coordination plane. 1 dissociates a proton of site B first to give an infinite zigzag-chain compound 1', while 2 dissociates a proton of site A first to give a cyclic-tetranuclear compound 2'. 2' undergoes a further deprotonation to give an electrically neutral di-deprotonated complex 2". The interconversion between the protonated monomer and the deprotonated oligomer/polymer was investigated by pH-dependent potentiometric and absorption spectrometric titrations.
TL;DR: In this paper, the average surface density of pre-main-sequence stars in the Orion, Ophiuchus, Chamaeleon, Vela, and Lupus star-forming regions was calculated as a function of angular distance from each star.
Abstract: We study clustering of pre-main-sequence stars in the Orion, Ophiuchus, Chamaeleon, Vela, and Lupus star-forming regions. We calculate the average surface density of companions, ?(?), as a function of angular distance, ?, from each star. We employ the method developed by Larson in a 1995 study for the calculation. In most of the regions studied, the function can be fitted by two power laws (? ??) with a break as found by Larson for the Taurus star-forming region. The power index, ?, is smaller at small separations than at large separations. The power index at large separations shows significant variation from region to region (-0.8 < ? < -0.1), while the power index at small separations does not (? ~ -2). The power index at large separations relates to the distribution of the nearest-neighbor distance. When the latter can be fitted by the Poisson distribution, the power index is close to 0. When the latter is broader than the Poisson distribution, the power index is negatively large. This correlation can be interpreted as the result of the variation in the surface density within the region. At large separations, the power-law fit may indicate star formation history in the region and not the spatial structure like the self-similar hierarchical, or fractal, one. Because of the velocity dispersion, stars move from their birthplaces, and the surface density of coeval stars decreases with their age. When a star-forming region contains several groups of stars with different ages, a power law may fit the average surface density of companions for it. The break of the power law is located around 0.01-0.1 pc. There is a clear correlation between the break position and the mean nearest-neighbor distance. The break position may reflect dispersal of newly formed stars.
TL;DR: Results indicate that vagus nerve stimulation preferentially exerts protective antiarrhythmic effects against PVT induced by sympathetic neural stimulation in this model, while it occasionally induces slow MVT under conditions in which sympathetic nerve activity in potentially elevated.
Abstract: Previous evidence has shown that vagal nerve activity modulates ventricular arrhythmias in patients and in animal models. However, the effects of direct vagus nerve stimulation on ventricular tachyarrhythmias brought by direct sympathetic nerve stimulation have not been elucidated. In the present study, the effects of electrical stimulation of the left cervical vagus nerve on ventricular tachycardia (VT) which was induced by electrical stimulation of the left ansae subclaviae (LAS) in rabbits were assessed. Monophasic action potentials (MAPs) of the left ventricular endocardium were recorded simultaneously with surface ECG. In 27 rabbits tested, the stimulation of LAS induced VT in 19 rabbits. Polymorphic VT (PVT) was induced in 14 rabbits (PVT group), whereas monomorphic VT (MVT) was induced in 5 rabbits (MVT group). Vagus nerve stimulation during the sympathetically-induced PVT led to a restoration of sinus rhythm in 10 of 14 rabbits, while that during the sympathetically-induced MVT did not restore sinus rhythm in any of the 5 rabbits. Vagus nerve stimulation during the stimulation of LAS, which was of subthreshold intensity for the induction in VT, did not result in an induction of PVT in any of the 14 rabbits in the PVT group, while it induced slow MVT in 3 of 5 rabbits in the MVT group. These results indicate that vagus nerve stimulation preferentially exerts protective antiarrhythmic effects against PVT induced by sympathetic neural stimulation in this model, while it occasionally induces slow MVT under conditions in which sympathetic nerve activity is potentially elevated.
TL;DR: In this paper, a linear correlation was found between the concentration of acid amount of the catalysts and the specific rate of iso-butene formation, which strongly suggests that the acidic sites play a key role in the iso butene formation.
Abstract: Metal pyrophosphates catalyse the oxidative dehydrogenation of iso-butane to iso-butene at 450–550°C using a feed gas of 75 mol% iso-butane and 5% O 2 . Ni 2 P 2 O 7 is the most selective catalyst with the iso-butene selectivity reaching to a maximum value of 82.2% at 550°C. Ag 4 P 2 O 7 and Zn 2 P 2 O 7 are also effective, but the iso-butene selectivities were slightly lower than that of Ni 2 P 2 O 7 . Pyrophosphates of Mg, Cr, Co, Mn, and Sn catalyse the oxidative dehydrogenation, but the iso-butene selectivity was 43.8–65.7% at the temperature where the maximum iso-butene yield is observed. The optimum oxygen concentration for iso-butene formation was 5–15 mol%, but the increase in O 2 concentration did not increase the iso-butene selectivity. No adsorbed oxygen species was found by means of TPD. The lattice oxygen of the pyrophosphates began to react with H 2 at 200–400°C. Reactivity of the lattice oxygen of pyrophosphates can be estimated from the value of ΔH f 0 for the corresponding oxide. More than 2 desorption peaks were observed in the TPD spectra of NH 3 adsorbed on the pyrophosphates, and a linear correlation was found between the concentration of acid amount of the catalysts and the specific rate of iso-butene formation. This strongly suggests that the acidic sites play a key role in the iso-butene formation.
TL;DR: In this paper, a non-dispersive solvent extraction of lactic acid based on anion exchange reaction with tri-n-octylmethylammonium chloride dissolved in oleyl alcohol was attempted in a microporous hollow fiber membrane device.
TL;DR: In this article, the catalytic dehydrofluorination of CF 3 CH 3 was studied over various metal phosphate catalysts in a fixed-bed reactor, and the results showed that the rate-determining step is the cleavage of the C-F bond.
Abstract: The catalytic dehydrofluorination of CF 3 CH 3 was studied over various metal phosphate catalysts in a fixed-bed reactor The Mg 2 P 2 O 7 catalyst exhibited the moderate activity and high selectivity of CF 2 CH 2 , and it is the most suitable catalyst for the dehydrofluorination of CF 3 CH 3 Deactivation did not take place during the 100 h reaction over the Mg 2 P 2 O 7 catalyst, and XRD patterns of the catalyst were unchanged after 100 h reaction However, small amounts of F − ions were present on the surface of the catalyst from results of XPS The active sites for CF 2 CH 2 formation are weak acid sites of the catalysts, and carbon deposition and/or polymerization take place on strong acid sites Results of CF 3 CH 3 -TPD indicated that the dehydrofluorination proceeds through a + CF 2 CH 3 carbonium-ion mechanism over Mg 2 P 2 O 7 catalyst, and the rate-determining step is the cleavage of the C–F bond
02 Nov 1998
TL;DR: A conceptual model, the so-called “image externalization loop” model, is introduced as a framework to realize an efficient 3D object creation environment and a 3D shape forming method for implementing the model is described in detail.
Abstract: 1. ABSTRACT While many sophisticated 3D rendering methods are available to produce realistic output, 3D data input still is a tedious and time-consuming task. This paper proposes a new method for modeling 3D objects using hand gestures. First of all, a conceptual model, the so-called “image externalization loop” model, is introduced as a framework to realize an efficient 3D object creation environment. Then, a 3D shape forming method for implementing the model is described in detail. Two-handed spatial and pictographic gestures are used to describe the features of the object in shape, size and deformation pattern. The implicit superquadric functions apply to build a deformable 3D model with blending and axial deformations as their extensions. A generic hand gesture learning and recognition facility is developed and used to translate the gestures into specific superquadrics parameters to deform the object. Finally, some experimental results are shown to express the capability and usefulness of the proposed method with its potentia! application areas.
TL;DR: In this article, an adult man entered an oil separator room to remove waste oil from a vacuum pump in a geothermal power plant. He suddenly collapsed and died soon after and toxicological analysis of sulfide and thiosulfate in blood, brain, lung, femoral muscle was made using the extractive alkylation technique combined with gas chromatography/mass spectrometry (GC/MS).
Abstract: An adult man entered an oil separator room to remove waste oil from a vacuum pump in a geothermal power plant. He suddenly collapsed and died soon after. Since hydrogen sulfide gas was detected in the atmosphere at the scene of the accident, poisoning by this gas was suspected and toxicological analysis of sulfide and thiosulfate in blood, brain, lung, femoral muscle was made using the extractive alkylation technique combined with gas chromatography/mass spectrometry (GC/MS). The concentrations of sulfide in these tissues were similar to those previously reported for fatal cases of hydrogen sulfide gas. The concentration of thiosulfate in the blood was at least 48 times higher than the level in control samples. Based on these results, the cause of death was attributed to hydrogen sulfide gas poisoning.
TL;DR: In this paper, the authors isolated rat UCP2 cDNA, which has been proposed to play an important role in mammalian thermogenesis and body weight regulation, and the nucleotide sequence of the cDNA revealed that the rat protein is composed of 309 amino acid residues, and is 99% and 95% identical to the mouse and human proteins, respectively.
TL;DR: In this paper, the authors investigated the fatigue behavior of polycrystalline Ni-base superalloy Udimet 720 Li and its statistical characteristics, four point bending fatigue test of plain specimens were carried out at room temperature.
12 Oct 1998
TL;DR: In this article, the effects of applied voltage modes on the positive corona discharge morphology and NO removal characteristics from air streams are experimentally investigated, and the basic principle for designing AC/DC energized streamer corona is also presented.
Abstract: In this paper, the effects of the applied voltage modes on the positive corona discharge morphology and NO removal characteristics from air streams are experimentally investigated. By using a DC superimposed high frequency AC power supply (10-60 kHz), a uniform streamer corona can be generated, which is also less sensitive to electrode mis-arrangements. Hermstein glow can he transferred to streamer corona if the peak-to-peak voltage is larger than 1.0 kV at the voltage change rate of 0.2 kV//spl mu/s. A significant amount of NO removal is observed under streamer corona. For the Hermstein glow, the removal is negligible. Moreover, the basic principle for designing AC/DC energized streamer corona is also presented in this paper.
TL;DR: An electrochemiluminescence (ECL) sensor having a Pt electrode coated with a tris(2,2′-bipyridine)ruthenium (II)(Ru(II) complex)-modified chitosan responded to oxalic acid more strongly than to several other substrates as mentioned in this paper.
TL;DR: In this article, the tensor magnetic reluctivity was defined and calculated from the data measured with two-dimensional measurement method, and the calculated results were in good agreement with measured ones.
Abstract: This paper deals with analysis by FEM for iron losses considering vector magnetic properties. We define the tensor magnetic reluctivity and calculate it from the data measured with two-dimensional measurement method. This numerical method is applied to the direct magnetic loss analysis. As a result, it is shown that the calculated results using our method are in a good agreement with measured ones.
TL;DR: These results suggest not only that the region is a membrane-binding domain of DnaA protein but also that these basic amino acids are important for the binding and the ionic interaction between thebasic amino acids and acidic residues of cardiolipin and is involved in the interaction between DnA protein and cardiolipsin.
TL;DR: It is indicated that a combination of two or three of these tests seems to provide a rapid diagnosis of invasive aspergillosis and assist in the evaluation of the development and severity of invasive Aspergillus fumigatus.
Abstract: We compared PCR, galactomannan detection assay using a latex agglutination test and (1-->3)-beta-D-glucan detection assay in detecting infection in rats experimentally infected with Aspergillus fumigatus. On day 2 after inoculation, (1-->3)-beta-D-glucan and nested PCR were positive for 80%, while galactomannan detection assay was positive for 60%. In addition, the positive result of nested PCR (87.5%) was higher than those of galactomannan detection assay (75%) and (1-->3)-beta-D-glucan (71.4%) on day 3 after inoculation. The sensitivity of nested PCR was superior to those of galactomannan detection assay and (1-->3)-beta-D-glucan detection assay. The three diagnostic tests were compared with histopathological findings, and the sensitivity of three diagnostic tests was correlated with histopathological changes. In addition, the elevated levels of (1-->3)-beta-D-glucan paralleled the development and progression of pulmonary aspergillosis. Our results indicate that a combination of two or three of these tests seems to provide a rapid diagnosis of invasive aspergillosis and assist in the evaluation of the development and severity of invasive aspergillosis.
TL;DR: It is suggested that sevoflurane modulated the amplitude of the GABA responses, depending on the balance of the accelerated activation and decay phases, and that the glycine-induced ICl was suppressed in a non-competitive manner without noticeable effect on the kinetics.