Quantum tetrahedra and simplicial spin networks

A new link between tetrahedra and the group SU(2) is pointed out: by associating to each face of a tetrahedron an irreducible unitary SU(2) representation and by imposing that the faces close, the concept of the quantum tetrahedron is seen to emerge. The Hilbert space of the quantum tetrahedron is introduced and it is shown that, due to an uncertainty relation, the “geometry of the tetrahedron” exists only in the sense of “mean geometry”.A kinematical model of quantum gauge theory is also proposed, which shares the advantages of the loop representation approach in handling in a simple way gauge- and diff-invariances at a quantum level, but is completely combinatorial. The concept of quantum tetrahedron finds a natural application in this model, giving a possible interpretation of SU(2) spin networks in terms of geometrical objects.     

Spectral studies of heterocyclic β-diketonates of actinide,lanthanide, and transition metals

The results of absorption spectral studies of the 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone chelates of thorium, uranyl, neodymium, gadolinium, gallium, and iron are presented. These neutral chelates exhibit u.v. spectra very similar to that of the ligand, with slight bathochromic or hypsochromic shifts. The solution stability of the complexes in acetonitrile, ethanol, and chloroform was also studied and the lanthanide complexes were found to be the least stable. Sinha's parameter is calculated for the neodymium chelate to determine the relative degree of covalency upon complexation.     

Study on phase stabilization and electrical performance of BICO0.20−xNIxVOX solid electrolyte

BICO_0.20?xNI_xVOX solid electrolyte in the composition range 0 ≤ x ≤ 0.20 was synthesized by standard solid-state reactions. The influence of Ni substitution for Co on the relationship between the phase stabilization and electrical performance was investigated by means of X-ray powder diffraction (XRPD), differential thermal analysis (DTA) and AC impedance spectroscopy. The highly conductive γ′-phase was effectively stabilized at room temperature for compositions with x ≥ 0.13 whose thermal stability increases with Ni content. On the other hand, complex plane plots of impedance suggested a major contribution of polycrystalline grain interiors to the overall electrical conductivity and the fastest oxygen-vacancy diffusion in the perovskite vanadate layers at x = 0.13. The dielectric permittivity measurements revealed the fact that suppression of the ferroelectric transition is compositionally dependent. However, a maximum ionic conductivity at lower temperatures (～2.56 × 10^?4 S cm^?1 at 300 °C) was observed for the composition with x = 0.13.     

The effect of soil particle size on soil radon concentration

It has been suggested in the literature that the radon concentration in the soil gas is related to the particle size distribution of the soil. This paper examines this relation. Radon concentration was measured in the soil on the Carboniferous limestone south of Buxton in Derbyshire, England, using the can technique. At each site, a sample of soil was taken at the bottom of the hole in which the dosimeter was placed to determine the particle size distribution.

The correlations between the raw values of radon concentration, soil particle size fractions and elevation were weak. Nevertheless, the kriged maps of radon, silt, clay and elevation showed some spatial relation to one another. The kriged estimates showed stronger correlations among these properties, especially between radon and elevation.     

A new tripod PPN bridging ligand and its copper,silver and palladium complexes: syntheses,characterizations and X-ray structures

A new tripod bridging ligand 2-{bis(diisopropylphosphino)methyl}-1-methylimidazole, MeImCH(Pi-Pr₂)₂ (PPN) was synthesized conveniently by reacting 2-{bis(trimethylsilyl)methyl}-1-methylimidazole and chlorodiisopropylphosphine. The dicationic dinuclear complex [Cu₂(PPN)₂][ClO₄]₂ (1) was prepared by the reaction of the ligand with [Cu(MeCN)₄]ClO₄ in acetonitrile. The reaction of the ligand with AgNO₃ in propane-2-ol followed by addition of NH₄PF₆ led to the formation of a similar type complex [Ag₂(PPN)₂][PF₆]₂ (2). The X-ray diffraction studies of 1 and 2 revealed a μ₂-η¹:η² tripod-like bonding of the PPN ligand, with one P and one N atom chelating to one metal ion and the remaining one P atom binds to another metal ion, affording a face-to-face type molecule. An eight-membered M₂P₄C₂ and a 10-membered M₂P₂N₂C₄ ring are thus formed with this new functional diphosphine ligand. In both complexes the two metal ions are held in very close proximity [2.6707 Å for 1 and 2.859(3) Å for 2]. Complex 1 underwent a rapid ligand exchange process in solution. Besides these dinuclear complexes the ligand also afforded a mononuclear palladium complex, [PdCl₂(PPN)] (3), when it was treated with an equimolar amount of [PdCl₂(PhCN)₂] in benzene. In 3 the ligand acts as a bidentate chelate through its two phosphorus atoms, leaving the imidazole donor dangling. On the other hand, a P,P-bridged dinuclear Pd(I) complex [Pd₂Cl₂(PPN)₂] (4) was achieved by reacting two moles of the ligand with one mole of [PdCl₂(PhCN)₂], followed by the addition of one mole of Pd(dba)₂ [dba=dibenzylideneacetone].     

Electrochemical biosensor based on supported planar lipid bilayers for fast detection of pathogenic bacteria

This paper presents a new ion-channel biosensor based on supported bilayer lipid membrane for direct and fast detection of Campylobacter species. The sensing element of a biosensor is composed of a stainless-steel working electrode, which is covered by artificial bilayer lipid membrane (BLM). Antibodies to bacteria embedded into the BLM are used as channel forming proteins. The biosensor has a strong signal amplification effect, which is defined as the total number of ions transported across the BLM. The total number of (univalent) ions flowing through the channels is 10¹⁰ ions s⁻¹. The biosensor showed a very good sensitivity and selectivity to Campylobacter species.     

Efficient synthesis of some novel furo[3,2-e]pyrazolo[3,4-b]pyrazines and related heterocycles

A series of novel 6-functionalized-5-amino-3-methyl-1-phenyl-1H-furo[3,2-e]pyrazolo[3,4-b]pyrazines (4a–c) was synthesized by the reaction of 3-methyl-6-oxo-1-phenyl-6,7-dihydro-1H-pyrazolo[3,4-b]pyrazine-5-carbonitrile (2) with α-halocarbonyl compounds such as: diethyl 2-bromomalonate, phenacyl bromide and chloroacetone. Cyclocondensation of the amino benzoyl 4b with diethyl malonate yielded the oxopyridine carboxylate derivative 5. Also, the starting intermediate amino ester compound 4a was allowed to react with ethanol amine to afford the hydroxyethyl caboxamide derivative 6. Furthermore, hydrazinolysis of the amino ester 4a afforded the corresponding amino carbohydrazide 7 which was used as a versatile precursor for synthesis of other heterocyclic compounds attached or fused to the furopyrazolopyrazine moiety. The chemical structures of the newly synthesized compounds were confirmed on the basis of elemental and spectral analyses containing FT-IR, ¹H NMR, ¹³C NMR, and mass spectrometry hoping these molecules should allow us to investigate their pharmacological activities in the future study.     

Synthesis and characterization of some new pyridines,thieno[2,3-b] pyridines and pyrido[3′,2′:4,5]thieno[3,2-d]pyrimidine-4(3H)-ones bearing styryl moiety

3-Cyano-5-ethoxycarbonyl-6-methyl-4-styrylpyridine-2(1H)-thione ( 3 ) was prepared by reaction of 2-cyano-5-phenylpenta-2,4-dienethioamide ( 2 ) with ethyl acetoacetate or by multicomponent reaction of cinnamaldehyde ( 1 ), cyanothioacetamide and ethyl acetoacetate in a moderate yield. Reaction of compound 3 with some N-aryl-2-chloroacetamides, in the presence of sodium acetate, gave the corresponding 2-(N-arylcarbamoylmethylsulfanyl)-3-cyano-5-ethoxycarbonyl-6-methyl-4-styrylpyridines 4a-f . When compounds 4a-f were subjected to Thorpe-Ziegler reaction conditions, they converted into the corresponding 3-amino-5-ethoxycarbonyl-2-(N-arylcarbamoyl)-6-methyl-4-styrylthieno[2,3-b]pyridines 5a-f . Compounds 5a,e,f were reacted, in turn, with 2,5-dimethoxytetrahydrofuran to furnish the corresponding 3-(pyrrol-1-yl)thieno-pyridines 6a,e,f . Reactions of 5a-f with triethyl orthoformate or nitrous acid were also carried out and their products were identified. Structural formulas of all synthesized compounds was characterized and confirmed on the basis of their elemental and spectral analyses.