Polymorphism of new rubidium magnesium monophosphate

Novel phase RbMgPO₄, synthesized by solid state reaction, sustains phase transitions at 169 and 184 °C. The medium (β)- and high- (γ) temperature forms (orthorhombic, respectively Pna2₁ and Pnma, Z=4) are typical stuffed tridymites but the ambient form (α) exhibits an unusual three-fold Pna2₁ superstructure that results from the change of coordination of one third of the Mg atoms. Cell parameters are as follows: for α: a=26.535(1) Å, b=9.2926(3) Å, c=5.3368(2) Å; for β: a=8.7938(3) Å, b=9.3698(3) Å, c=5.3956(1) Å; for γ: a=8.7907(3) Å, b=5.4059(1) Å, c=9.3949(3) Å.     

Femtosecond digital in-line holography with the fractional Fourier transform: application to phase-contrast metrology

The possibility to analyze transparent phase objects using femtosecond digital in-line holography is demonstrated. We show that the diffraction patterns produced by the diffraction of 20-fs pulses by pure phase objects can be advantageously processed by using the fractional Fourier transform. The optimal fractional orders lead to the longitudinal location of the phase object while the analysis of the reconstructed patterns leads to its diameter and to the value of the phase shift. Simulations and experimental results are in good concordance. This work shows new important applications of these reconstruction techniques in the domain of digital phase-contrast metrology. We further show that the use of femtosecond pulses results in a significant reduction of coherent noise.     

FTIR features of lithium-iron phosphates as electrode materials for rechargeable lithium batteries

The essential structural features of lithium-metal phosphates (LMP) have been studied using FTIR spectroscopy which is a sensitive tool to probe the local environment in the solid materials. Various LMP materials where M is iron have been investigated including phospho-olivine LiFePO(4), diphosphate LiFeP(2)O(7), Nasicon-type phosphate Li(3)Fe(2)(PO(4))(3) and dihydrate FePO(4).2H(2)O. Vitreous and amorphous materials are also considered. Analysis of internal and external modes of vibration allows to distinguish between the different phases and the type of cationic environment in the framework. Results corroborate the contribution of the main factors which are responsible for the complexity of the spectra, i.e. departure from ideal symmetry, interactions between polyhedra, bridging atoms and lattice distortion.     

Anticancer effect of three pyrazole derivatives

The evaluation of the cytotoxic properties in vitro of three synthetic tripods containing pyrazole: N,N-bis[(3,5-dimethylpyrazol-1-yl)methyl]aniline (1); N,N-tetrakis[(3,5-dimethylpyrazol-1-yl)methyl]-para-phenylenediamine (2); and N,N-tetrakis-[(1,5-dimethylpyrazol-3-yl)methyl]-para-phenylenediamine (3), was examined for their cytotoxic activity on two tumor cell lines: P815 (murin mastocytoma) and Hep (human laryngeal carcinome). While the compound 2 shows a small cytotoxic activity, compounds 1 and 3 are more cytotoxic against both cell lines. However, this cytotoxicity is more pronounced against Hep cell line (IC50: 3.25 microg mL(-1) for compound 1 and 6.92 microg mL(-1) for compound 3) than P815 cell line (IC50: 17.82 microg mL(-1) for compound 1 and 37.21 microg mL(-1) for compound 3). Statistical analysis shows that the compound 1 is two- to threefold more cytotoxic than compound 3 (P < 0.05). Interestingly, the cytotoxicity induced by compound 1 against Hep cell line is more important than that induced by adriamycin used as a positive control.     

On Directed Sets and their Suprema

The aim of this paper is to investigate partially ordered real linear topological spaces in which directed sets admit a supremum in their closure. In particular, we point out that this property is intimately related to the normality of the ordering cone and also to the Scott continuity of functionals belonging to the nonnegative polar of the ordering cone. Research of Mohamed Ait Mansour was supported by LACO (Laboratoire d'Arithmétique, Calcul Formel et Optimisation), UMR-CNRS 6090, University of Limoges and Agence Universitaire de la Francophonie.     

Symbolic computation for center manifolds and normal forms of Bogdanov bifurcation in retarded functional differential equations

In this paper, we present explicit formulas for computing the coefficients of a center manifold for the Bogdanov singularity in autonomous retarded functional differential equations with parameters. As a consequence, normal forms associated with the flow on a center manifold up to an arbitrary order are derived. The explicit formulas have been implemented using the computer algebra system Maple. The paper ends with some examples given in order to show the applicability of the methodology and the convenience of the computer software.     

Chemical composition, antibacterial and antioxidant activities of the essential oils from Thymus satureioides and Thymus pallidus

This study was designed to examine the in vitro antibacterial and antioxidant activities of the essential oils (EOs) of Thymus satureioides (T.s) and T. pallidus (T.p). EOs were isolated by steam distillation and analyzed by capillary gas chromatography and gas chromatography coupled to mass spectrometry (GC-MS). The major constituents of the volatile fraction of T. satureioides were bomeol (29.5%), carvacrol (9.1%), and beta-caryophyllene (8.2%), while those of T. pallidus were camphor (29.8%), dihydrocarvone (17.6%), bomeol (7.6%) and camphene (7.5%). The essential oils were tested against a panel of Gram+ and Gram- bacteria by using agar diffusion and broth dilution methods. The data indicated that the Gram-positive Bacillus subtilis was the most sensitive strain producing an average inhibition zone of 51.7 mm. Furthermore, Pseudomonas aeruginosa, known as a resistant strain, was also sensitive. The samples were also subjected to screening for their possible antioxidant activity by using the 2,2-diphenyl-l-picrylhydrazyl (DPPH) assay. The IC50 values of the oil of T. satureioides and T. pallidus were 0.32 and 11.6 mg/mL, respectively.     

Phase equilibrium properties of binary aqueous solutions of benzylamine, 1,2-bis(2-aminoethoxy)ethane,or 2-[2-(dimethylamino)ethoxy]ethanol

The vapour pressures of (benzylamine + water), {1,2-bis(2-aminoethoxy)ethane + water}, or {2-[2-(dimethylamino)ethoxy]ethanol + water} binary mixtures, and pure 2-[2-(dimethylamino)ethoxy]ethanol component were measured by means of two static devices at temperatures between (283.15 and 363.15 (or 323.15)) K. The data were correlated with the Antoine equation. From these data, excess Gibbs functions (G^E) were calculated for several constant temperatures and fitted to a fourth-order Redlich–Kister equation using the Barker’s method. The (benzylamine + water) binary mixture exhibits positive deviations in G^E for (303.15 < T/K < 323.15) and a sinusoidal shape in G^E for T > 323.15 K over the whole composition range. The aqueous 1,2-bis(2-aminoethoxy)ethane or {2-[2-(dimethylamino)ethoxy]ethanol + water} solutions exhibit negative deviations in G^E for all investigated temperatures over the whole composition range.