Sectionally Semicomplemented Distributive Nearlattices

A nearlattice S is a meet semilattice together with the property that any two elements possessing a common upper bound have a supremum. Here the authors have introduced the notion of sectionally semicomplemented distributive nearlattices and given several characterizations of them. The skeleton SCon(S) of Con(S), the congruence lattice, consists of all those nearlattice congruences which are the pseudocomplements of members of Con(S). The relationship between skeletal congruences and kernel of skeletal congruences leads to numerous characterizations of sectionally semicomplemented distributive nearlattices and semiboolean algebras. For example we prove, for a distributive nearlattice S with 0, the following conditions are equivalent:

Precision measurement of neutrino oscillation parameters at INO-ICAL detector

A magnetized Iron CALorimeter (ICAL) detector at the India-based neutrino observatory (INO) is used to study neutrino oscillation sensitivity using atmospheric muon neutrino source. The ICAL detector will be able to detect muon tracks and hadron showers produced by neutrino interactions with the iron target. We have performed precision measurement analysis for the atmospheric neutrino oscillation parameters with the muon neutrino events, generated by Monte Carlo NUANCE event generator. A marginalized χ² analysis based on reconstructed neutrino energy and muon zenith angle binning scheme has been performed to determine the sensitivity for the atmospheric neutrino mixing parameters, \(\sin ^{2}\theta _{23}\) and \(| {\Delta } m^{2}_{23}|\).     

Thermal and spectroscopic characterization of several derivatives containing a new organic ring system

Several derivatives containing a new organic ring system, the tropane-6-spiro-5-hydantoin structure (namely 8-alkyl-8-azabicyclo [3.2.1.] octane-6-spiro-5-imidazoline-2,4-diones) have been characterized by thermal (DSC and simultaneous DTA-TG-DTG) and spectroscopic techniques (IR,¹ H-NMR,¹³ C-NMR). X-ray powder diffraction and elemental analysis were applied for structural and molecular characterization. All the compounds melt in the range 160–250°C and undergo decomposition with progressive mass loss after the solid-liquid thermal transition with molecular degradation. It was found that tropane-6-spiro-5-hydantoin derivatives with the hydantoin ring in position are thermally less stable than those containing this ring in position.One of the authors (Dr. M.V.) thanks partial financial support from CICYT through research project PA 86-0317. Thanks are extended to Ms. A. García and Mr. J. C. Rivero for artwork.     

Enzymatic—spectrophotometric determination of phytic acid with phytase from Aspergillus ficuum

A method to determine phytic acid in the range 3–60 μM based on the spectrophotometric determination of inorganic phosphate with vanadate and molybdate, after liberation by enzymatic hydrolysis of phytic acid with phytase from Aspergillus ficuum at pH 2.5 and 37 °C is reported. The method has been applied successfully to determine phytic acid in wheat flour and in a pharmaceutical product.     

Synthesis and ligand properties towards gold and silver of the ferrocenylamidobenzimidazole ligand

The treatment of FcCOCl (Fc = (C₅H₅)Fe(C₅H₄)) with aminobenzimidazole in 1:1 or 2:1 ratio gives the ferrocenyl-amido derivatives FcCO(benzimNH₂) or (FcCO)₂(NHbenzim), respectively. The reactivity of FcCO(benzimNH₂) with silver or gold complexes has been studied. The reaction with the basic gold compounds [Au(acac)(PPh₃)] or [O(AuPPh₃)₃]ClO₄ occurs with deprotonation of the NH₂ group and coordination of one or three gold(phosphine) fragments. The treatment of this ligand with silver compounds, such as Ag(OTf) or [Ag(OTf)(PPh₃)], gives the complexes of stoichiometry [Ag(OTf)L] or [Ag(OTf)(PPh₃)L]. The ligand FcCO(benzimNH₂) and the complex [Ag(OTf){FcCO(benzimNH₂)}(PPh₃)] have been characterized by X-ray diffraction studies. DFT calculations were performed on models of this dimeric silver complex and showed that dimerization is energetically favourable, because Ag(I) achieves a four coordination environment, despite some bonds being relatively weak.     

Trinuclear Gold(I) Complexes with Various Coordination Modes of N,N-dimethyldithiocarbamate

The compounds [Au₃(S₂CNMe₂)₃{ ₃-(PPh₂)₃CH]} (1) and [Au₃(S₂CNMe₂)(-S₂CNMe₂){ ₃-(PPh₂)₃CH}]ClO₄ (2) are obtained by reaction of [Au₃Cl₃{ ₃-(PPh₂)₃CH}] with three equivalents of sodium dimethyldithiocarbamate or two equivalents of the same reagent in the presence of excess NaClO₄. Reaction of 2 with the group 11 metal complexes [AuCl(tht)], CuCl or [Au(C₆F₅)(tht)] takes place with displacement of [M(S₂CNMe₂)]_n (M=Cu, Au) and formation of the new complexes [Au₃X(-S₂CNMe₂){ ₃-(PPh₂)₃CH}]ClO₄ (X=Cl (3), X=C₆F₅ (4)); further reaction of 3 with [Ag(OClO₃)(tht)] (tht=tetrahydrothiophene) affords the dicationic species [Au₃(-S₂CNMe₂){ ₃-(PPh₂)₃CH}(tht)](ClO₄)₂ (5). Treatment of [Au₃Cl₃{ ₃-(PPh₂)₃CH}] with one equivalent of NaS₂CNMe₂ allows the substitution of only one chlorine atom, giving rise to the complex [Au₃Cl₂(S₂CNMe₂){ ₃-(PPh₂)₃CH}] (6), in which the dithiocarbamate ligand acts as monodentate rather than bidentate bridging as observed in compounds 3–5. The crystal structures of complexes 1 and 2 have been established by X-ray diffraction studies and show close gold–gold contacts.     

Microstructured Polyacrylamide Hydrogels Prepared Via Inverse Microemulsion Polymerization

The synthesis by a two-stage polymerization process of microstructured polyacrylamide hydrogels with large swelling capacity and improved mechanical properties is reported. First, crosslinked polyacrylamide particles of nanosize scale are made by inverse microemulsion polymerization. These particles are then dried and redispersed in an aqueous solution of acrylamide and polymerized in the presence of a crosslinking agent. The microstructured hydrogels, in contrast to transparent conventional polyacrylamide hydrogels, are translucid due to the presence of the dispersed particles. The swelling capacity of these hydrogels increases as the particle content increases and their Young and elastic moduli (at equilibrium swelling) diminish only slightly. Mechanical tests disclose that the microstructured hydrogels have larger Young moduli than conventional hydrogels with an identical degree of swelling. Copyright 2001 Academic Press.     

Coefficient estimates of negative powers and inverse coefficients for certain starlike functions

For ?1≤B<A≤1, let \(\mathcal {S}^{*}(A,B)\) denote the class of normalized analytic functions \(f(z)= z+{\sum }_{n=2}^{\infty }a_{n} z^{n}\) in |z|<1 which satisfy the subordination relation z f ^′(z)/f(z)?(1 + A z)/(1 + B z) and Σ^?(A,B) be the corresponding class of meromorphic functions in |z|>1. For \(f\in \mathcal {S}^{*}(A,B)\) and λ>0, we shall estimate the absolute value of the Taylor coefficients a _n (?λ,f) of the analytic function (f(z)/z)^?λ . Using this we shall determine the coefficient estimate for inverses of functions in the classes \(\mathcal {S}^{*}(A,B)\) and Σ^?(A,B).