Seasonal variations of cytosolic antioxidant enzyme activities in the liver and white muscle of thinlip gray mullet (Liza ramada Risso) from the Adriatic Sea

The activity of cytosolic antioxidative defence enzymes in the liver and white muscle of thinlip gray mullet (Liza ramada Risso) were compared in winter and spring in the Adriatic Sea. Activity of antioxidative enzymes is functionally organized due to metabolic demands: analyses of variance and correlation analysis revealed tissue- and seasonal- specific organization of antioxidative enzymes. In winter GST activity increased in both tissues compared with spring. At the same time decreased GSH-Px and GR activities were observed and this effect was more pronounced in liver then in white muscle. From correlation analyses it is concluded that the antioxidative components correlate, but the composition of the antioxidative defence system is different in respect to season and tissue. This means that the antioxidative defence system reorganizes its structure due to oxidative demands and to protect the tissues against reactive oxygen species and to establish homeostasis. Discriminant analyses separated groups according to the complete organization of individual components of the system very well and identified individual components (CAT, GST and GR) which contribute most to the differences. Statistical differences were observed between enzyme activities in tissues (liver and muscle) in both winter and spring, and between seasons (winter and spring) for liver tissue only. Since environmental parameters, such as temperature and oxygen concentration in the sea differ with season, we conclude that in this species the tissues examined expressed their antioxidative defence systems in different ways in respect of external/environmental conditions. We propose that tissue- and seasonal- specific levels of antioxidant enzyme activities should be considered in the interpretation of data from future biomonitoring field studies, especially in relation to low temperature.     

Three points method for searching the best least absolute deviations plane

In this paper a new method for estimation of optimal parameters of a best least absolute deviations plane is proposed, which is based on the fact that there always exists a best least absolute deviations plane passing through at least three different data points. The proposed method leads to a solution in finitely many steps. Moreover, a modification of the aforementioned method is proposed that is especially adjusted to the case of a large number of data and the need to estimate parameters in real time. Both methods are illustrated by numerical examples on the basis of simulated data and by one practical example from the field of robotics.     

Crystal structure of rosmanol-9-ethylether

The title compound: 2H-10,4a-(epoxy-methano)-phenantren-12-one-1,3,4,9,10,10a-hexahydro-5,6-dihydroxy-9-etoxy-1,1-dirnethyl-7-(1-methylethyl), was isolated fromSalvia officinalis L. andHyssopus officinalis L. C₂₂H₃₀O₅, orthorhombic, P2₁2₁2₁, (No. 19)a=8.309(1),b=11.320(2),c=22.060(3) Å,V=2075.0(9) ų,Z=4,D _x=1.199 g·cm^–3, (CuK)=1.54184 Å,=6.43 cm^–1, F(000)=808,T=296(1) K. The structure was solved by direct methods and refined toR=0.047 for 1824 observed reflections collected on a CAD-4 diffractometer. In the course of structure refinement conformational disorder of the isopropyl moiety and the terminal methyl group pertaining to the ethoxy ligand was established. They result altogether in four different conformers.Alternatively it can be termed 9-ethoxyrosmanol.     

Rheological model optimization using advanced evolutionary computation for the analysis of the influence of recycled rubber on rubber blend dynamical behaviour

Rheological models of tested rubber blend samples, with different ratios of smut/recycled material, were developed, analyzed and discussed according to experimental data. The experimental measurements show the dynamical behavior of these samples after a short-term axial load. The rheological model of samples was assumed as a viscoelastic Voigt-Maxwell and hyperelastic Mooney-Rivlin model. Real coded genetic algorithms were implemented for optimal model parameters identification in order to minimize the difference between the real sample behavior and dynamical model output. Numerical results obtained for analyzed mixture were compared with the original sample to verify the presented method. In purpose of predicting the dynamical characteristics for desirable rubber blends, an interrelation was formed based on the concentration of recycled material in sample blends and dynamical model parameters dependence.     

Electrochemical behaviour of rosmanol 9-ethyl ether,a diterpene lactone antioxidant isolated from sage

The electrochemical behaviour and mechanism of the redox process of the natural antioxidant rosmanol 9-ethyl ether, isolated fromSaliva officinalis L., were studied. The cyclic voltammograms of rosmanol 9-ethyl ether (R9EE), at characteristic pH values, and the electrochemical parameters for all investigated pH values were measured. Three characteristic pH regions, each with different behaviour of R9EE, were identified. In regions of pH < 4 and pH > 5 only one anodic peak appeared, whereas in the solutions of pH 4–5 two anodic peaks could be noted. The overall oxidation mechanism at pH < 4 is an e.H.e.H. oxidation mechanism, which as a final product gives a quinonic molecule. The influence of pH on the second oxidation peak potential tends towards zero in accordance with the preceding dissociation of the one of phenolic groups, thus suggesting an e.e.H. mechanism at pH > 5. This means that at the pH values expected in plant cells, R9EE has an unexpected structure, making this substance a potent antioxidant. Electrochemical and spectrophotometric measurements enabled us to establish an extremely low pK _a value (4.35) for R9EE.     

Two counterfeit coins

We consider the problem of ascertaining the minimum number of weighings which suffice to determine the counterfeit (heavier) coins in a set of n coins of the same appearance, given a balance scale and the information that there are exactly two heavier coins present. An optimal procedure is constructed for infinitely many n's, and for all other n's a lower bound and an upper bound for the maximum number of steps of an optimal precedure are determined which differ by just one unit. Some results of Cairns are improved, and his conjecture at the end of [3] is proved in a slightly modified form.     

Asymmetric vibrations and stability of a rotating annular plate loaded by a torque

The paper investigates transverse vibration of a thin annular plate clamped at its inner edge to a rigid shaft, while its outer edge is clamped to a rigid cylinder. The shaft and the outer edge of the plate are loaded by torques of the same intensity, but of opposite directions. The whole structure rotates at a constant angular speed. The solution has been determined using Galerkin’s method. The obtained results illustrate the impact of the torque, angular speed and inner and outer radia ratio to transverse asymmetric vibration frequency of the plate. Stability of the plate has been examined and critical values of angular speed and torque leading to the loss of stability of the plate have been determined. Some mode shapes have been drawn and the influence of torque and angular speed on nodal lines has been shown.     

Electron impact ionization cross sections of beryllium and beryllium hydrides

We report calculated electron impact ionization cross sections (EICSs) for beryllium (Be) and some of its hydrides from the ionization threshold to 1 keV using the Deutsch-Märk (DM) and the Binary-Encounter-Bethe (BEB) formalisms. The positions of the maxima of the DM and BEB cross sections are very close in each case while the DM cross section values at the maxima are consistently higher. Our calculations for Be are in qualitative agreement with results from earlier calculations (convergent close-coupling, R matrix, distorted-wave and plane-wave Born approximation) in the low energy region. For the various beryllium hydrides, we know of no other available data. The maximum cross section values for the various compounds range from 4.0 × 10^?16 to 9.4 × 10^?16 cm² at energies of 44 to 56 eV for the DM cross sections and 3.0 × 10^?16 to 5.4 × 10^?16 cm² at energies of 40.5 to 60 eV for the BEB cross sections.