Flat and weakly flat projection algebras

The notion of a projection algebra was first introduced in [4] by Ehrig et al. as an algebraic version of ultrametric spaces. Computer scientists use this notion as a convenient means of algebraic specification of process algebras. Some algebraic notions regarding these algebras have been studied in [1], [2], [5]. The flat projection algebras have been investigated by the authors in [1]. Here we completely characterize flat and weakly flat (m-separated and separated) projection algebras. Received November 19, 2001; accepted in final form December 1, 2002. RID="h1" ID="h1"     

A Facile Synthesis of Stable Phosphorus Ylides Containing Chlorine and Sulfur Derived from 6-Chloro-2-benzoxazolethiol and 2-Chloro-phenothiazine

Stable crystalline phosphorus ylides containing chlorine and sulfur were obtained in excellent yields from the 1:1:1 addition reaction between triphenylphosphine and dialkyl acetylene-dicarboxylates in the presence of 6-chloro-2-benzoxazolethiol and 2-chloro-phenothiazine. These stable ylides exist in solution as a mixture of two geometrical isomers. This is caused by the conjugation of the ylide moiety with the adjacent carbonyl group, which results in a restricted rotation around the respective carbon-carbon bond.     

A study of starch addition on burst effect and diameter of polyurethane microspheres containing theophylline

Theophylline was encapsulated in polyurethane prepared with hexamethylene diisocyanate (HMDI), polycaprolactone (PCL) (M_W = 530 and 2000 g/mol) diols, and starch as polyols and butanediol as chain extender. Polyurethane microspheres were prepared in two reactors; after polyurethane preparation by mixing PCL/starch, HMDI and theophylline in the first reactor, microspheres formation was achieved by transferring the reaction mixture to an aqueous medium (moving at 5000 rpm) of the second reactor. Fourier transform infrared (FTIR) was employed to confirm polyurethane formation during the course of reactions. FTIR spectrum revealed bands at 1729–1733 cm^?1 and 3340–3347 cm^?1 which indicates carbonyl and NH of amine groups, respectively. Scanning electron microscopy (SEM) was used to study the morphology of the samples. SEM confirmed the formation of microspheres with spherical morphology. Particle size investigation with optical microscopy revealed a size distribution of 8–70 µm. Controlled release of theophylline from the microspheres was performed in phosphate buffered saline (PBS) at pH = 7.4 and monitored with a ultraviolet (UV) spectrometer at 274 nm. Drug release profiles showed that starch addition reduced the release rate around 24% for microspheres prepared from PCL with a molecular weight of 2000 g/mol and it had negligible effect on a molecular weight of 530 g/mol. Copyright © 2007 John Wiley & Sons, Ltd.     

The minimal flavour violation benchmark in view of the latest LHCb data

We derive the consequences of the MFV hypothesis for ΔF=1$\mathrm{\Delta }F=1$ flavour observables based on the latest LHCb data. Any future measurement beyond the MFV bounds and relations unambiguously indicates the existence of new flavour structures next to the Yukawa couplings of the Standard Model.     

Crystal‐to‐Crystal Transformation: An HgII Metal–Organic Polymer Constructed with a Triazole Ligand

A new one‐dimensional double‐chain Hg^II coordination polymer containing the ligand 3,5‐bis(4‐pyridyl)‐4‐amino‐1,2,4‐triazole (bpatrz) and thiocyanate anions, namely, {[Hg₂(μ‐bpatrz)(μ‐SCN)₂(SCN)₂] · MeOH}_n ( 1 ), has been synthesized and structurally characterized by single‐crystal X‐ray diffraction. Compound 1 displays bright blue luminescence with emission maxima around 370 and 440 nm in solution and the solid state, respectively. Uptake and release of MeOH by 1 were investigated by powder X‐ray diffraction, thermogravimetric analysis, elemental analysis, and IR and NMR spectroscopy.     

Chemoselective synthesis of xanthenes and tetraketones in a choline chloride-based deep eutectic solvent

A chemoselective synthesis of tetraketone and xanthene derivatives, by means of tandem Knoevenagel condensation and Michael addition in choline chloride-based deep eutectic solvents (DESs), is presented. The reaction of readily available aldehydes and active methylene compounds in malonic acid- and ZnCl₂-based DES gives various xanthenes derivatives with good to excellent yields under mild reaction conditions. On the other hand, tetraketones were synthesized in almost quantitative yields by simple condensation of an aldehyde and active methylene compounds in milder deep eutectic solvents of urea and SnCl₂. In addition, the reaction of other types of choline chloride-based DES leads to a mixture of tetraketone and xanthene.     

Efficient synthesis of novel quinazoline-4(1H)-one derivatives by N-halosulfonamides

Research on Chemical Intermediates - In this research, a facile, effective and one-pot synthesis of new quinazoline-4(1H)-one derivatives is reported. Isatoic anhydride, acid hydrazides or ammonium...