Nonmonotone inexact restoration approach for minimization with orthogonality constraints

Numerical Algorithms - Minimizing a differentiable function restricted to the set of matrices with orthonormal columns finds applications in several fields of science and engineering. In this...     

Antiplasmodial and cytotoxic activities of drimane sesquiterpenes from Canella winterana

The hexane extract from the leaves of Canella winterana exhibited strong activity against the chloroquine sensitive (CQS) strain of Plasmodium falciparum (D10) in vitro (IC50 2.53 microg/mL). Bioassay guided fractionation of this extract has led to the isolation of 5 drimane-type sesquiterpenoids: 9-epideoxymuzigadial, 9-deoxymuzigadial, muzigadial, 3-beta-acetoxypolygodial and the newly isolated hemiacetal, named muzigodiol, with IC50-values of 1.01, 2.19, 0.31, 2.77 and 7.43 microg/mL, respectively. The first four compounds were tested for their cytotoxicity using Chinese Hamster Ovarian (CHO) cells, where they showed IC50-values of 1.82, 33.69, 1.18, and 58.31 microg/mL, respectively. A structure-activity relationship is discussed.     

Molecular structure and bonding character of mono and divalent metal cations (Li+, Na+, K+, Be2+, Mg2+, and Ca2+) with substituted benzene derivatives: AIM,NBO, and NMR analyses

Cation–π complexes between several cations (Li⁺, Na⁺, K⁺, Be²⁺, Mg²⁺, and Ca²⁺) and different π-systems such as para-substituted (F, Cl, OH, SH, CH₃, and NH₂) benzene derivatives have been investigated by UB3LYP method using 6-311++G** basis set in the gas phase and the water solution. The ions have shown cation–π interaction with the aromatic motifs. Vibrational frequencies and physical properties such as dipole moment, chemical potential, and chemical hardness of these compounds have been systematically explored. The natural bond orbital analysis and the Bader’s quantum theory of atoms in molecules are also used to elucidate the interaction characteristics of the investigated complexes. The aromaticity is measured using several well-established indices of aromaticity such as NICS, HOMA, PDI, FLU, and FLUπ. The MEP is given the visual representation of the chemically active sites and comparative reactivity of atoms. Furthermore, the effects of interactions on NMR data have been used to more investigation of the studied compounds.     

On the theory of stability of matrix differential equations

We establish the conditions of asymptotic stability of a linear system of matrix differential equations with quasiperiodic coefficients on the basis of constructive application of the principle of comparison with a Lyapunov matrix-valued function.     

Expression of Recombinant Human Epidermal Growth Factor in Escherichia coli and Characterization of its Biological Activity

Recombinant human epidermal growth factor (EGF) was successfully expressed as a fusion protein in Escherichia coli system. This system was used OmpA signal sequence to produce soluble protein into the periplasm of E. coli. Human EGF (hEGF) synthesized in bacterial cell was found to be similar in size with the original protein and molecular weight approximately at 6.8 kDa. Cell proliferation assay was conducted to characterize the biological activity of hEGF on human dermal fibroblasts. The synthesized hEGF was found to be functional as compared with authentic hEGF in stimulating cell proliferation and promoting growth of cell. In comparison of biological activity between synthesized and commercial hEGF on cell proliferation, the results showed there was no significant different. This finding indicates the synthesized hEGF in E. coli system is fully bioactive in vitro.     

Chemical composition and antibacterial activity of essential oils from leaves, stems and flowers of Salvia reuterana Boiss. grown in Iran

The essential oils obtained by hydrodistillation of the leaves, stems and flowers of Salvia reuterana (Lamiaceae) were analysed by GC and GC/MS. Germacrene D and beta-caryophyllene were the major constituents in all the three oils: (28.5, 27.7 and 32.5%) and (15.5, 11.4 and 16.6%), respectively. Bicyclogermacrene (10.2 and 13.2%) was also prodominated in the stem and flower oils. The composition of the oils was mostly quantitativel rather than qualitatively different. All the oils consisted mainly of sesquiterpenes and a small percentage of non-terpenoid compounds. In all the three oils, monoterpenes were in a concentration less than 0.5%. Antibacterial activity was determined by the measurement of growth inhibitory zones.     

Simultaneous Quantification of 3′- and 6′-Sialyllactose in Rat Plasma Using Liquid Chromatography-Tandem Mass Spectrometry and Its Application to a Pharmacokinetic Study

Sialyllactose (SL), an acidic oligosaccharide, has immune-protective effects against pathogens and helps with the development of the immune system and intestinal microorganisms. To elucidate the pharmacokinetic characterization after oral administration to rats, the simultaneous quantification method for 3′-SL and 6′-SL in rat plasma was validated, using liquid chromatography-tandem mass spectrometry (LC-MS/MS) in an electrospray ionization (ESI) mode. Several types of columns [C18, amide, and hydrophilic interaction liquid chromatography (HILIC) phase] were used to separate the peaks of 3′-SL and 6′-SL, which improved chromatographic selectivity. Ultimately, the HILIC phase column had a good peak shape and quick resolution, with a mobile phase comprising ammonium acetate buffer and acetonitrile obtained by gradient elution. In addition, the simultaneous quantification of 3′-SL and 6′-SL in rat plasma samples were adequately applied to pharmacokinetic study.     

Stability of the motion of linear large-scale oscillating systems

A method for setting up a time-periodic Lyapunov function for a linear system with periodic coefficients based on an auxiliary matrix-valued function is proposed and developed. New sufficient conditions for the stability of large-scale periodic systems decomposed into an even number of subsystems are formulated