Negative inotropism of terpenes on guinea pig left atrium: structure-activity relationships

The aim of this work was to evaluate the pharmacological effect of seven structurally related terpenes on the contractility of cardiac muscle. The effect of terpenes was studied on isolated electrically driven guinea pig left atrium. From concentration–response curves for inotropic effect were determined the EC₅₀ and relative potency of such terpenes. Our results revealed that all terpenes, except phytol, showed ability to reduce the contractile response of guinea pig left atrium. Further, relative potency was directly related to the number of isoprene units and to the lipophilicity of the compounds. For example, sesquiterpenes farnesol and nerolidol showed higher relative potency when compared with the monoterpenes citronellol, geraniol and nerol. We can conclude that most of the evaluated terpenes showed a promising negative inotropism on the atrial muscle. Future studies are necessary to investigate their action mechanism.     

Complexes of octadecyltrimethylammonium polyacrylate: properties in solution,gel and solid forms

A polymer-surfactant complex (OTAPA) was prepared by titration of aqueous poly(sodium acrylate) with stoichiometric amounts of octadecyltrimethylammonium chloride. The resulting product is not water-soluble and does not dissolve in most polar and nonpolar, liquids. OTAPA has peculiar thermal behaviour and interesting structural properties. It has a high melting temperature and decomposes around 350 °C. According to preliminary X-ray findings, the complex is formed by an arrangement of alkyl chains around the polymer skeleton, packed into a layered structure. The complex forms an elastic gel in ethylene glycol, and, to a much lesser extent, in glycerol or tetrahydrofuran, but is hardly water-soluble. Indeed, the occurrence of micelle-assisted dissolution and the precipitation of OTAPA from such mixtures, upon dilution with water, have been observed. Applications of OTAPA as a hydrophobic modifier of surfaces can be considered.     

Monitoring of an industrial process by multivariate control charts based on principal component analysis

The control and monitoring of an industrial process is performed in this paper by the multivariate control charts. The process analysed consists of the bottling of the entire production of 1999 of the sparkling wine "Asti Spumante". This process is characterised by a great number of variables that can be treated with multivariate techniques. The monitoring of the process performed with classical Shewhart charts is very dangerous because they do not take into account the presence of functional relationships between the variables. The industrial process was firstly analysed by multivariate control charts based on Principal Component Analysis. This approach allowed the identification of problems in the process and of their causes. Successively, the SMART Charts (Simultaneous Scores Monitoring And Residual Tracking) were built in order to study the process in its whole. In spite of the successful identification of the presence of problems in the monitored process, the Smart chart did not allow an easy identification of the special causes of variation which casued the problems themselves.     

Ab initio HF versus semi-empirical results of chemisorption calculations of hydrogen on graphite

The regular chemisorption of hydrogen on graphite in four different configurations has been studied with a Hartree-Fock ab initio technique. No stable phase was found; previous CNDO calculations indicated stable adsorption to occur in three cases out of four. However, the positions of relative minima and the corresponding electronic structure are reasonably described by the semi-empirical scheme.     

Homogenization for strongly anisotropic nonlinear elliptic equations

In this paper we present homogenization results for elliptic degenerate differential equations describing strongly anisotropic media. More precisely, we study the limit as e? 0 \epsilon \to 0 of the following Dirichlet problems with rapidly oscillating periodic coefficients:¶¶ . \cases {{ -div(\alpha(\frac{x}{\epsilon}}, \nabla u) A(\frac{x}{\epsilon}) \nabla u) = f(x) \in L^{\infty}(\Omega) \atop u = 0 su \eth\Omega\ } ¶¶where, p > 1,     a: \Bbb Rⁿ ×\Bbb Rⁿ ? \Bbb R,     a(y,x) ? áA(y)x,x?^p/2-1, A ? M^{n ×n}(\Bbb R) p>1, \quad \alpha : \Bbb R^n \times \Bbb R^n \to \Bbb R, \quad \alpha(y,\xi) \approx \langle A(y)\xi,\xi \rangle ^{p/2-1}, A \in M^{n \times n}(\Bbb R) , A being a measurable periodic matrix such that A^t(x) = A(x) 3 0A^t(x) = A(x) \ge 0 almost everywhere.¶¶The anisotropy of the medium is described by the following structure hypothesis on the matrix A:¶¶l^2/p(x) |x|² ￡ áA(x)x,x? ￡ L ^2/p(x) |x|², \lambda^{2/p}(x) |\xi|^2 \leq \langle A(x)\xi,\xi \rangle \leq \Lambda ^{2/p}(x) |\xi|^2, ¶¶where the weight functions l \lambda and L \Lambda (satisfying suitable summability assumptions) can vanish or blow up, and can also be "moderately" different. The convergence to the homogenized problem is obtained by a classical compensated compactness argument, that had to be extended to two-weight Sobolev spaces.     

Thermochemistry of Li, Na, K, Rb and Cs alkylated phenoxides

Lattice energies and thermochemical radii of the anions OR⁻ (R = 2-Me; 2,6-Me₂; 2,4,6-Me₃; 2,6-t-Bu₂) in alkali metal phenoxides, MOR (M = Li, Na, K, Rb and Cs) were investigated based on the corresponding standard molar enthalpies of formation determined by reaction-solution calorimetry. The results obtained at 298.15 K were as follows: (MOR, cr)/kJ mol⁻¹ = −398.4 ± 1.1 (LiO-2-MePh), −423.4 ± 1.6 (LiO-2,6-Me₂Ph), −457.3 ± 7.1 (LiO-2,4,6-Me₃Ph), −346.6 ± 1.4 (NaO-2-MePh), −399.1 ± 1.5 (NaO-2,6-Me₂Ph), −422.4 ± 7.1 (NaO-2,4,6-Me₃Ph), −496.6 ± 7.1(NaO-2,6-t-Bu₂Ph), −367.8 ± 1.2 (KO-2-MePh), −399.1 ± 1.4 (KO-2,6-Me₂Ph), −368.8 ± 1.2 (RbO-2-MePh), −403.6 ± 1.3 (RbO-2,6-Me₂Ph), −387.0 ± 1.6 (CsO-2-MePh) and −413.6 ± 1.3 (CsO-2,6-Me₂Ph). Estimates of thermochemical raddi, lattice energies and standard enthalpies of formation of not experimentally measured alkali metal phenoxides was successfully done with a model based on the Kapustinskii equation and the set of values experimentally determined.     

The importance of radiochemistry for the characterization of NORM and of environments contaminated by NORM

Naturally occuring radioactive materials (NORM) are present in the environment and they can be concentrated by technical activities, particularly those involving natural resources. This article describes radioanalytical problems arising in the accurate determination of natural radionuclides in NORM and in the environment contaminated by NORM. The solution of these problems is of particular importance since the results can be used to estimate the dose to workers and to the population. A special emphasis is given to the reliability of the radiochemical methods and procedures applied for the detection and measurement of alpha or beta emitters by radiometric or non-radiometric techniques.