On a diophantine problem of P. Erdös

Research supported in part by Grant 4055 from the Hungarian National Foundation for Scientific Research and by Kereskedelmi és Hitelbank Rt. Universitas Foundation.     

Kinetic study on the homogeneous esterification of acetic acid with isoamyl alcohol

The liquid‐phase esterification of acetic acid and isoamyl alcohol has been studied to develop a kinetic model using a sequential experimental design based on the divergence criterion. Data come from batch reactor experiments, performed in the temperature range of 316–363 K. Discrimination among 36 possible kinetic models, written in terms of activity, mole fractions, and molar densities, is possible through the deviance information criterion, as estimated by a Markov chain Monte Carlo technique. The obtained results indicate a negligible heat of reaction and a clear autocatalytic effect of acetic acid on the esterification rate. © 2012 Wiley Periodicals, Inc. Int J Chem Kinet 45: 10–18, 2013     

Transitive Quasi-Uniformities and Topogenous Orders

The purpose of the present paper is to show that the concept of topogenous order, introduced in [1] and discussed in detail in [2], can be useful in answering questions concerning transitive quasi-uniformities.     

Simultaneous Extensions of Topogenities

Let (X,) be a topological space, X _i X for i I, and < _i be a topogenity on X _i . We look for a topogenity < on X such that is the topology induced by < and <|X _i =< _i for i I.     

Effect of gamma-radiation in vinylpyrrolidone

The effects of gamma-irradiation in purified N-vinylpyrrolidone monomer have been studied. Dependence of crosslinking and water swelling ability upon the administered dose of ionizing radiation have been documented.     

Achievement of pH-independence of poorly-soluble, ionizable loratadine by inclusion complex formation with dimethyl-β-cyclodextrin

A tricyclic, piperidine derivative of antihistamines, loratadine, which belongs in class II of the Biopharmaceutical Classification System, was investigated. It is an ionizable drug, whose solubility depends on the gastrointestinal pH, and the bioavailability is therefore very variable. The aim of this work was to enhance the dissolution and make the solubility of loratadine independent of pH. Inclusion complexes were prepared between loratadine and dimethyl-β-cyclodextrin in two different molar ratios by three techniques (physical mixing, kneading and spray-drying). The formation and physicochemical properties of the inclusion complexes were investigated by means of dissolution tests, thermal analysis and Fourier Transform Infrared spectroscopy. The instrumental examinations proved the presence of partial or total complexes depending on the preparation method and molar ratio, which resulted in better dissolution. For some compositions and preparation methods, the application of this cyclodextrin made the solubility of loratadine independent of pH.     

On Barycentric Interpolation. II (Grünwald–Marcinkiewicz type Theorems)

Grünwald–Marcinkiewicz type theorems with respect to barycentric Lagrange interpolation based on equidistant and Chebyshev node-sytems in [–1, 1] are proved. It turns out that the results are very similar to the ones known for the classical Lagrange interpolation.