Synthesis of 4-Alkynyl-substituted 3,4-Dihydropyrimidin-2(1H)-ones

4-Alkynyl-3,4-dihydropyrimidin-2-(1H)-ones were synthesized by a one-pot reaction of propynals, ethyl acetoacetate, and urea. The yields of acetylenic dihydropyrimidinones depend significantly upon the propynal structure and catalyst type. A comparative study of the catalysts revealed an important advantage of polyphosphate ester in tetrahydrofuran in comparison with hydrochloric acid in methanol or trimethylchlorosilane in dimethylformamide, allowing the preparation of target compounds in good or moderate yields.     

The eigenpairs of a Sylvester–Kac type matrix associated with a simple model for one-dimensional deposition and evaporation

A straightforward model for deposition and evaporation on discrete cells of a finite array of any dimension leads to a matrix equation involving a Sylvester–Kac type matrix. The eigenvalues and eigenvectors of the general matrix are determined for an arbitrary number of cells. A variety of models to which this solution may be applied are discussed.     

Bioactive materials for bone regeneration based on zinc-modified hydroxyapatite

1. Download : Download high-res image (167KB)
2. Download : Download full-size image

     

On the Effects of UV Radiation on the Release Ability of Glucose Embedded in Hydroxypropyl Cellulose Films

New drug delivery systems based on hydroxypropyl cellulose (HPC) and different percents of glucose were prepared and characterized to check their suitability as UV resistant patches. The spectral absorption properties of the HPC and HPC-glucose blends before and after UV irradiation were analyzed. The surface polarity and hydrophilicity were correlated with the morphology of the films and analyzed with respect to the UV exposure time and the embedded amount of glucose. The effects of UV radiation on in vitro evaluation of glucose release from the HPC films are reported. The mechanism involved in the drug release process, evaluated using the Korsmeyer-Peppas equation, was dependent on the introduced amount of glucose and less on the UV exposure time. A more polar, smoother, and less dense surface releases the glucose over larger periods of time, making the system with lower percents of glucose more adequate for the pursued purpose.     

Full four‐component relativistic calculations of the one‐bond 77Se–13C spin‐spin coupling constants in the series of selenium heterocycles and their parent open‐chain selenides

Four‐component relativistic calculations of ⁷⁷Se–¹³C spin–spin coupling constants have been performed in the series of selenium heterocycles and their parent open‐chain selenides. It has been found that relativistic effects play an essential role in the selenium–carbon coupling mechanism and could result in a contribution of as much as 15–25% of the total values of the one‐bond selenium–carbon spin‐spin coupling constants. In the overall contribution of the relativistic effects to the total values of ¹J(Se,C), the scalar relativistic corrections (negative in sign) by far dominate over the spin‐orbit ones (positive in sign), the latter being of less than 5%, as compared to the former (ca 20%). A combination of nonrelativistic second‐order polarization propagator approach (CC2) with the four‐component relativistic density functional theory scheme is recommended as a versatile tool for the calculation of ¹J(Se,C). Solvent effects in the values of ¹J(Se,C) calculated within the polarizable continuum model for the solvents with different dielectric constants (ε 2.2–78.4) are next to negligible decreasing negative ¹J(Se,C) in absolute value by only about 1 Hz. The use of the locally dense basis set approach applied herewith for the calculation of ⁷⁷Se–¹³C spin‐spin coupling constants is fully justified resulting in a dramatic decrease in computational cost with only 0.1–0.2‐Hz loss of accuracy. Copyright © 2014 John Wiley & Sons, Ltd.     

The preparation and properties of “porous silicon–nickel ferrite” nanoheterocomposites for gas detectors

This paper discusses the preparation and properties of gas detectors based on “porous silicon–nickel ferrite” nanocomposites. Impedance spectroscopy was used to measure sensitivity to ethanol and isopropanol vapours in the presence of an alternating electric field. The results were interpreted with the help of an equivalent electrical circuit. In the analysis of the resistive–capacitive properties in the equivalent circuit a constant phase element was used.     

Room temperature MgI2-catalyzed Friedel–Crafts reaction between electron-rich (het)arenes and ethyl glyoxylate

Magnesium iodide-catalyzed addition of electron-rich (het)arenes to ethyl glyoxylate proceeds at room temperature with high chemoselectivity to afford ethyl 2-(het)aryl- 2-hydroxyacetates in yields up to 95%.     

Synthesis and structure of new chlorine containing calix[4]resorcinols

1. Download : Download high-res image (91KB)
2. Download : Download full-size image