Mathematical Analysis and Application of Iron-Wire Neuron Model

A mathematical model for the behavior of passive iron in concentrated nitric acid, based on the electrochemical mechanism, is proposed. The model is capable of explaining several phenomena including threshold for activation, monostable property, periodic activation, propagation of activation and threshold for propagation. Furthermore, the mathematical model shows that the electrochemical active line has a specific propagated waveform and velocity of propagation.     

A case of xanthogranuloma of the urinary bladder

A case of xanthogranuloma of the urinary bladder is reported. A 68-year-old man was referred to our hospital for the evaluation of microscopic hematuria. At that time, he did not have an abdominal tumor and ultrasonography showed no abnormality of the kidneys and the bladder wall. Two months later, he was admitted with the chief complaints of perineal discomfort and non tender fist size mass was palpable in the lower abdomen. Ultrasonography, computed tomographic scan and magnetic resonance imaging MRI demonstrated a supravesical mass which was strongly suspected as urachal tumor. Total cystectomy with urachal resection was performed. The histological diagnosis was xanthogranuloma. The patient has been in good health without recurrence, 4 years after surgery. We discuss xanthogranuloma of the urinary bladder in the literature.     

NO Reduction with CO in the Presence of O2 over Cu/Al2O3 (3) – Structural Analysis of Active Species by Means of XAFS and UV/VIS/NIR Spectroscopy

The local structure around Cu supported on Al₂O₃ was determined by UV/VIS/NIR and XAFS spectroscopic techniques. The relationship between catalytic performance for NO–CO–O₂ reaction and the state of supported Cu species is discussed. A new method for estimating the fraction of aggregated to isolated Cu species is proposed.     

Low temperature selective catalytic reduction of NO by NH3 over V2O5 supported on TiO2–SiO2–MoO3

The V₂O₅ catalysts supported on TiO₂–SiO₂–MoO₃ (TSM) prepared by the coprecipitation method were investigated for the selective catalytic reduction (SCR) of NO by NH₃ at low temperatures. The V₂O₅/TSM catalyst with 7–13 wt% SiO₂ was found to exhibit a superior SCR activity and a good sulfur tolerance at low temperatures (<250 °C). The presence of highly active polymeric vanadates formed by the incorporation of MoO₃ to TiO₂–SiO₂ and superior redox properties seems to enhance SCR activity, and furthermore the very lower SO₂ oxidation activity due to the higher acidity leads to the remarkable improvement of sulfur tolerance.     

Mechanistic study on lithium intercalation using a restricted reaction field in LiNi0.5Mn0.5O2

Structure changes of LiNi_0.5Mn_0.5O₂ were detected at the electrode/electrolyte interface of lithium cell using synchrotron X-ray scattering and two-dimensional model electrodes. The electrodes were constructed by an epitaxial film of LiNi_0.5Mn_0.5O₂ synthesized by pulsed laser deposition (PLD) method. The orientation of the film depends on the substrate plane; the 2D layer of LiNi_0.5Mn_0.5O₂ is parallel to the SrTiO₃(1 1 0) substrate ((1 1 0) LiNi_0.5Mn_0.5O₂//(1 1 0) SrTiO₃), while the 2D layer is perpendicular to the SrTiO₃(1 1 1) substrate ((0 0 3) LiNi_0.5Mn_0.5O₂//(1 1 1) SrTiO₃). The in situ X-ray diffraction of LiNi_0.5Mn_0.5O₂(0 0 3) confirmed three-dimensional lithium diffusion through the two-dimensional transition meal layers. The intercalation reaction of LiNi_0.5Mn_0.5O₂ will be discussed.     

Probing the Structure, Stability and Hydrogen Adsorption of Lithium Functionalized Isoreticular MOF-5 (Fe, Cu, Co, Ni and Zn) by Density Functional Theory

Li adsorption on isoreticular MOFs with metal Fe, Cu, Co, Ni and Zn was studied using density function theory. Li functionalization shows a considerable structural change associated with a volume change in isoreticular MOF-5 except for the Zn metal center. Hydrogen binding energies on Li functionalized MOFs are seen to be in the range of 0.2 eV, which is the desired value for an ideal reversible storage system. This study has clearly shown that Li doping is possible only in Zn-based MOF-5, which would be better candidate to reversibly store hydrogen.     

Dehydration of 1,4-butanediol over supported rare earth oxide catalysts

Vapor-phase catalytic dehydration of 1,4-butanediol was investigated over rare earth oxides supported on ZrO₂. In the dehydration of 1,4-butanediol, 3-buten-1-ol was mainly produced, together with tetrahydrofuran (THF) and γ-butyrolactone. The heavy group of rare earth oxides, such as Dy₂O₃, Ho₂O₃, Er₂O₃, Tm₂O₃, Yb₂O₃, and Lu₂O₃, supported on monoclinic ZrO₂ showed higher selectivity to 3-buten-1-ol than pure monoclinic ZrO₂ and supported light rare earth oxides, such as La₂O₃ and Pr₆O₁₁. Supported Yb₂O₃ catalysts dispersed on other oxides, such as alumina, silica, and tetragonal ZrO₂ catalyze the formation of THF. X-ray diffraction (XRD) measurements reveal that cubic Yb₂O₃ crystallites dispersed on monoclinic ZrO₂ provide active sites in the dehydration of 1,4-butanediol to produce 3-buten-1-ol.     

Electrochemistry of LiMn2O4 epitaxial films deposited on various single crystal substrates

LiMn₂O₄ epitaxial thin films were synthesized on SrTiO₃:Nb(1 1 1) and Al₂O₃(0 0 1) single crystal substrates by pulsed laser deposition (PLD) method and the electrochemical properties were discussed comparing with that of amorphous LiMn₂O₄ film on polycrystalline Au substrate. LiMn₂O₄ epitaxial film showed only a single plateau in charge–discharge curves and a single redox peak at the corresponding voltage of cyclic voltammograms. This phenomenon seems to originate from the effect of the epitaxy: the film is directly connected with the substrate by the chemical bond and this connection would suppress the phase transition of Li_xMn₂O₄ film during lithium (de-)intercalation. The discharge voltage of LiMn₂O₄ epitaxial film on SrTiO₃ was lower than that of LiMn₂O₄ film on Al₂O₃. This lowered discharge voltage may be caused by the electronic interaction between LiMn₂O₄ film and SrTiO₃:Nb n-type semiconductor substrate.     

One-pot syntheses of water-soluble poly(oxamide)s

Two kinds of water-soluble polymers were synthesized by using the poly(oxamide) polyanion generated in situ from the reductive coupling polymerization of diisocyanates induced by SmI₂. One is a nonionic polymer bearing oligo(ethylene oxide) pendants, which was obtained by treating the polyanion with α-methyl-ω-(4-bromomethyl)phenylmethyl oligo(ethylene oxide). The other is an ion-containing polymer having sulfonate moieties in the side chains, which was prepared by the reaction of the polyanion with 1,3-propane sultone or sodium 4-(bromomethyl)-benzenesulfonate. In both cases, the corresponding polymers were provided in good yields, and their solubilities were found to be dependent on the structure as well as the substitution degree. The poly(oxamide) with oligo(ethylene oxide) exhibited good solubilities in common organic solvents and was soluble in aqueous system at high level of substitution. On the other hand, the poly(oxamide) with propane-sulfonic acid showed high solubility in both acidic and basic water but was insoluble in organic solvents, while the poly(oxamide) having benzylsulfonate was soluble only in DMF and DMSO. Received: 18 October 1996/Revised: 8 November 1996/Accepted: 15 November 1996