Experimental examination of vortex-sound generation in an organ pipe: A proposal of jet vortex-layer formation model

Aero-dynamical models of sound generation in an organ pipe driven by a thin jet are investigated through an experimental examination of the vortex-sound theory. An important measurement requirement (acoustic cross-flow as an irrotational potential flow reciprocating sinusoidally) from the vortex-sound theory is carefully realized when the pipe is driven with low blowing pressures of about 60 Pa (jet velocities of about 10 m/s). Particle image velocimetry (PIV) is applied to measure the jet velocity and the acoustic cross-flow velocity over the mouth area at the same phase by quickly switching the jet drive and the loudspeaker-horn drive. The vorticity of the jet flow field and the associated acoustic generation term are evaluated from the measurement data. It is recognized that the model of the “jet vortex-layer formation” is more relevant to the sound production than the vortex-shedding model. The acoustic power is dominantly generated by the flow–acoustic interaction near the edge, where the acoustic cross-flow velocity takes larger magnitudes. The acoustic generation formula on the vortex sound cannot deny the conventional acoustical volume-flow model because of the in-phase relation satisfied between the acoustic pressure at the mouth and the acoustic volume flow into the pipe. The vortex layers formed along both sides of the jet act as the source of an accelerating force (through the “acceleration unbalance”) with periodically alternating direction to oscillate the jet flow and to reinforce the acoustic cross-flow at the pipe mouth.     

Local unitary transformation method for large-scale two-component relativistic calculations: case for a one-electron Dirac Hamiltonian

An accurate and efficient scheme for two-component relativistic calculations at the spin-free infinite-order Douglas-Kroll-Hess (IODKH) level is presented. The present scheme, termed local unitary transformation (LUT), is based on the locality of the relativistic effect. Numerical assessments of the LUT scheme were performed in diatomic molecules such as HX and X(2) (X = F, Cl, Br, I, and At) and hydrogen halide clusters, (HX)(n) (X = F, Cl, Br, and I). Total energies obtained by the LUT method agree well with conventional IODKH results. The computational costs of the LUT method are drastically lower than those of conventional methods since in the former there is linear-scaling with respect to the system size and a small prefactor.     

Wiggly strings of radial configuration in Kerr–Newman black hole

Previously we have investigated the cosmic wiggly strings in (3 + 1)-dimensional Schwarzschild, Reissner–Nordström and Kerr black holes. As an extension the solutions in (3 + 1)-dimensional axially symmetric charged rotating black hole are investigated. The solutions for the wiggly string exhibit open strings lying in the radial direction in the equatorial plane outside the horizon.     

Oxidation of 7,8‐diaminotheophylline with lead tetraacetate and reaction of the oxidation product, 6‐cyanoimino‐5‐diazo‐1,3‐dimethylpyrimidine‐2,4‐dione with alcohols or amines

Oxidation of 7,8‐diaminotheophylline (1) with lead tetraacetate in refluxing toluene gave a mixture of 3‐amino‐5,7‐dimethylpyrimido[4,5‐e][1,2,4]triazine‐6,8‐dione ( 2 ) and 6‐cyanoimino‐5‐diazo‐1,3‐dimethylpyrimidine‐2,4‐dione ( 4 ). The latter was transformed to 2 by the reaction with 1‐propanethiol in quantitative yield. The reaction of 4 with methanol, ethanol and 1‐propanol in the presence of rhodium ( II ) acetate gave 5‐alkoxy‐6‐(2‐alkyl‐3‐isoureido)‐1,3‐dimethylpyrimidine‐2,4‐diones ( 7a‐c ). A similar reaction of 4 with alkylamines such as n‐propylamine, n‐butylamine, isobutylamine and n‐hexylamine gave a mixture of 7‐alkyl‐8‐aminotheophyllines ( 8a‐d ) and (5‐alkylamino‐1,3‐dimethyl‐2,4‐dioxopyrimidin‐6‐yl)cyanamides ( 9a‐d ).     

Synthesis of the Carbohydrate Moiety of Glycoproteins from the Parasite Echinococcus granulosus and Their Antigenicity against Human Sera

Stereocontrolled syntheses of biotin-labeled oligosaccharide portions containing the carbohydrate moiety of glycoprotein from Echinococcus granulosus have been accomplished. Trisaccharide Galβ1-3Galβ1-3GalNAcα1-R (A), tetrasaccharide Galα1-4Galβ1-3Galβ1-3GalNAcα1-R (B), and pentasaccharide Galα1-4Galβ1-3Galβ1-3Galβ1-3GalNAcα1-R (C), (R = biotinylated probe) were synthesized by stepwise condensation and/or block synthesis by the use of 5-(methoxycarbonyl)pentyl 2-azido-4,6-O-benzylidene-2-deoxy-α-d-galactopyranoside as a common glycosyl acceptor. The synthesis of the tetrasaccharide and the pentasaccharide was improved from the viewpoint of reducing the number of synthetic steps and increasing the total yield by changing from stepwise condensation to block synthesis. Moreover, hexasaccharide E, which contains the oligosaccharide sequence which occurs in E. granulosus, was synthesized from trisaccharide D. We examined the antigenicity of these five oligosaccharides by an enzyme-linked immunosorbent assay (ELISA). Although compounds of C–E did not exhibit antigenicity against cystic echinococcosis (CE) patient sera, compounds B, D, and E showed good serodiagnostic potential for alveolar echinococcosis (AE).     

Reversible Oxygen Binding to the Polymeric Cobalt Tetraazaporphyrin Complex and Oxygen‐Facilitated Transport through Its Membrane

Summary: A membrane of a cobalt tetraazaporphyrin polymer complex was prepared with a nanometer thickness and used as an oxygen‐facilitated transport membrane. Rapid and reversible oxygen binding to the cobalt tetraazaporphyrin complex with a polymeric imidazole ligand was observed at low temperature. Oxygen transport through the membrane was facilitated and a high (oxygen/nitrogen) permselectivity of 28 was obtained.

Oxygen‐facilitated transport through a cobalt tetraazaporphyrin complex‐polymer membrane of nanometer thickness.     

Effects of indium,gallium, or bismuth additions on the discharge behavior of Al-Mg-Sn-based alloy for Al-air battery anodes in NaOH electrolytes

Journal of Solid State Electrochemistry - In this paper, the electrochemical performances of Al 0.5-Mg 0.1-Sn (wt%), Al 0.5-Mg 0.1-Sn 0.05 In (wt%), Al 0.5-Mg 0.1-Sn 0.05 Ga (wt%) and Al 0.5-Mg...     

Recent Advances in One-Electron-Oxidized CuII–Diphenoxide Complexes as Models of Galactose Oxidase: Importance of the Structural Flexibility in the Active Site

The phenoxyl radical plays important roles in biological systems as cofactors in some metalloenzymes, such as galactose oxidase (GO) catalyzing oxidation of primary alcohols to give the corresponding aldehydes. Many metal(II)–phenoxyl radical complexes have hitherto been studied for understanding the detailed properties and reactivities of GO, and thus the nature of GO has gradually become clearer. However, the effects of the subtle geometric and electronic structural changes at the active site of GO, especially the structural change in the catalytic cycle and the effect of the second coordination sphere, have not been fully discussed yet. In this Review, we focus on further details of the model studies of GO and discuss the importance of the structural change at the active site of GO.     

Formation of the CuII–Phenoxyl Radical by Reaction of O2 with a CuII–Phenolate Complex via the CuI–Phenoxyl Radical

Reaction of Cu(ClO₄)₂ ⋅ 6 H₂O with a tripodal 2N2O ligand, H₂Me₂NL, having a p-(dimethylamino)phenol moiety, in CH₂Cl₂/MeOH (1:1 v/v) under basic conditions under an inert gas atmosphere gave [Cu(Me₂NL)(H₂O)] ( 1 ). The same reaction carried out under aerobic conditions gave [Cu(Me₂NL)(MeOH)]ClO₄ ( 2 ), which could be obtained also from the isolated complex 1 by reaction with O₂ in CH₂Cl₂/MeOH. The X-ray crystal structures of 1 and 2 revealed similar square-pyramidal structures, but 2 showed the (dimethylamino)phenoxyl radical features. Complex 1 exhibits characteristic Cu^II EPR signals of the d ground state in CH₂Cl₂/MeOH at 77 K, whereas 2 is EPR-silent. The EPR and X-ray absorption fine structure (XAFS) results suggest that 2 is assigned to the Cu^II–(dimethylamino)phenoxyl radical. However, complex 1 showed different features in the absence of MeOH. The EPR spectrum of the CH₂Cl₂ solution of 1 exhibits distortion from the d ground state and a temperature-dependent equilibrium between the Cu^II–(dimethylamino)phenolate and the Cu^I–(dimethylamino)phenoxyl radical. From these results, Cu^II–phenoxyl radical complex 2 is concluded to be formed by the reaction of 1 with O₂ via the Cu^I–phenoxyl radical species.     

Generation and reactions of α-trifluoromethyl stabilized aziridinyl anion, a general synthetic precursor for stereospecific construction of α-amino-α-trifluoromethylated quaternary carbon

Optically pure α-trifluoromethylated aziridinyl anions react with various electrophiles to give the corresponding optically pure 2-trifluoromethyl-2-substituted aziridines, which are general synthetic precursors for optically pure α-amino-α-trifluoromethylated compounds, such as trifluoromethylated α/β-amino acids, in good yields.