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Abstract: In the present study, the spark plasma sintering technique is used to densify pre-alloyed TiAl powders. Ti49Al47Cr2Nb2 and Ti51Al44Cr2Nb2B1 powders are sintered at temperatures ranging between 1100°C and 1250°C to yield various microstructures. Two-phased (γ+α2), duplex and lamellar microstructures are generated depending on the powder and the sintering temperature. Full compaction is achieved in a short period of time and the overall processing duration does not exceed 30min. The resultant tensile properties at room temperature are very promising whereas a limited creep resistance was obtained at 700°C [Copyright &y& Elsevier]

Abstract: Four low-temperature phases with compositions Bi10Mo3O24, Bi6Mo2O15, Bi14Mo5O36 and Bi8Mo3O21 have been prepared by the n-butylamine wet synthesis method. They have been characterized by powder X-ray diffraction and transmission electron microscopy, mainly by selected area electron diffraction. The four phases present a close structural relationship and a common basic fluorite-type structure and are members of a homologous series of phases with general formula Bi2 n +4Mo n O6( n +1), being n=3, 4, 5 and 6, respectively. The matrices relating their superstructures and the basic fluorite type unit cell are given, as well as a general one for the whole series. The conductor behavior of these phases is characterized by impedance spectroscopy being all these materials very good ionic conductors. [Copyright &y& Elsevier]

Abstract: A wet chemistry method applied to the synthesis of bismuth–molybdenum oxides leads to the low temperature synthesis of a new phase with composition Bi10Mo3O24. The crystal data have been determined by ab initio indexing of the powder pattern. It crystallizes in the monoclinic system, with unit-cell parameters , , , and . A preliminary heavy-atom skeleton related to the fluorite structure allowed us to postulate a layer structure with composition [Bi10O12] n [MoO4]3n . This compound has been processed by spark plasma sintering as a ceramic material, exhibiting good ionic conductor properties in the whole temperature range of stability. [Copyright &y& Elsevier]

Studies the crystal structure of aquahydroxidocopper(II) oxovanadium(IV) vanadate Cu(H[sub2]O)(OH)VO(VO[sub4]). Arrangement of vanadate tetrahedra and distorted oxavanadium octahedra in the crystal structure; Values of bond-valence sums of atoms copper and vanadium present in the compound; Analysis of bond angles and bond distances in the compound.

Abstract: The kinetics of ultra-fast reaction rates in Cu–V2O5 and Ag–V2O5 diffusion couples during synthesis by SPS is investigated for temperatures ranging from 500°C to 600°C. The diffusion coefficient of the Cu and Ag ions in the Cu x V2O5 and Ag y V2O5 phases exhibit values comparable or higher than that of diffusion in liquids. However, the high values of activation energies (113 and 149kJ/mol for Cu and Ag in ε-Cu x V2O5 and δ-Ag y V2O5, respectively) are not compatible with liquid-like diffusion mechanisms. We interpret the fast diffusion kinetics observed as resulting from repulsive interactions between diffusing species, as reported in the literature. The role of repulsive interactions can also account for the lower diffusion coefficient of Ag with respect of Cu, the former existing in the +1 valence state, whereas the latter potentially exists in the +1 and +2 valence states. The higher activation energy of Ag with respect of Cu is interpreted as resulting from differences in diffusion paths in δ-Ag y V2O5 and ε-Cu x V2O5. [Copyright &y& Elsevier]

Abstract: A method based on the analysis of reaction layers that form in Cu x V2O5–Ag y V2O5 interdiffusion couples annealed by spark plasma sintering to quickly explore the Cu–Ag–V2O5 ternary system at high pressure is presented. Through use of microanalysis profiling, the phases occurring in this system have been obtained much faster than by conventional techniques of solid-state chemistry. Microdiffraction profiling has also been used to properly identify the Cu0.5Ag0.5V2O5 phase in the reaction layer between CuV2O5 and Ag0.8V2O5. The stability domains of the phases have been approximately determined and interpreted. In most cases, reaction kinetics occurs quickly, as expected by the high diffusion coefficient of Cu and Ag in V2O5. Though the experiments have been carried out under high pressure (75MPa), the same phases are obtained than with sealed quartz tubes experiments. [Copyright &y& Elsevier]

In this paper, the interaction of 10-TW laser pulses, focused at moderately relativistic intensity, with a supersonic helium gas-jet has been investigated by varying gas density and jet nozzle. We have successfully tested several advanced diagnostic devices to characterize the plasma and the accelerated electron bunches. Plasma densities have been measured by means of a femtosecond high-resolution interferometer, while the electron beams were analyzed with a stack of radiochromic films, a beam-profile monitor, a magnetic spectrometer, and a nuclear activation setup based on gamma-ray generation via electron bremsstrahlung. We present the results as well as the basic features and relevant details of such diagnostics whose performances can fit a large class of experiments. [ABSTRACT FROM AUTHOR]

Abstract: A mechanochemical activation route has been applied in order to obtain the n =1–4 and ∞ members of the Sr2[Sr n −1Ti n O3n +1] Ruddlesden–Popper series from different (n +1)SrO:nTiO2 mixtures. The mechanosynthesis of SrTiO3 and Sr2TiO4 was observed during the milling process from the initial stoichiometric mixture, but in the cases of the n =2–4 members, a subsequent thermal treatment was needed. The synthesis protocol of Sr3Ti2O7 has been greatly improved and this compound can be isolated as a single, crystalline phase after annealing at 800 °C. In the case of Sr4Ti3O10 and Sr5Ti4O13, the formation temperature was also decreased, but members with n =3 and 4 could not be isolated. Detailed investigations using electron microscopy methods (TEM, HREM and SAED) were carried out in the samples corresponding to n =2–4. Although a single ordered Sr3Ti2O7 structure is dominant in the sample corresponding to n =2, a few intergrowths of other Ruddlesden–Popper phases were observed. In the cases of n =3 and 4, the intergrowths of Ruddlesden–Popper phases are more frequent than in the n =2 composition and are randomly distributed in the sample. The more frequent occurrence of such stacking faults, with increasing n value, leads to a somewhat disordered layer stacking sequence. [Copyright &y& Elsevier]

Abstract: Two new series of diaminoacridinic derivatives obtained from proflavine and N-(6-amino-3-acridinyl)acetamide were synthesised and assessed for their cytotoxic and antileishmanial activities. Two compounds, N-[6-(acetylamino)-3-acridinyl]acetamide and N-[6-(benzoylamino)-3-acridinyl]benzamide demonstrated highly specific antileishmanial properties against the intracellular amastigote form of the parasite. Structure–activity relationships established that the antiproliferative activity against human cells was greatly enhanced by the presence of a benzoylamino group in 6-mono-substituted acridines, while the presence of two acetylamino or benzoylamino groups in 3,6-di-substituted acridines strongly increased the specificity of the molecules for Leishmania parasite, suggesting that symmetric conformations could preferentially interfere with Leishmania metabolism. [Copyright &y& Elsevier]

Abstract: A new mixed valence compound, NH4V3O7, as single crystals, has been synthesized hydrothermally. It crystallizes in the monoclinic system, space group I2/m with lattice parameters , , , , , . The crystal structure determined with consists of (V3O7) n layers linked by ammonium cations. The layer is built up by replication through symmetry elements of three independent distorted octahedra sharing edges and corners. The distortion of vanadium octahedra tends to vary and the coordination number CN is reasonably selected as equal to 5+1. KV3O7, synthesized by the mild hydrothermal route as a largely pure phase, is isostructural and its semi-conductive character is indicative of the presence of V4+ and V5+ sites. These are mixed valence compounds , the vanadium localization on three independent crystallographic sites enabling their electric behavior by electron hopping. [Copyright &y& Elsevier]

Abstract: Temperature, holding time and conditions of pressure application, three of the most important spark plasma sintering (SPS) parameters, have been reviewed to assess their effect on the densification and grain growth kinetics of a pure commercially available submicrometer-sized silicon carbide powder. Experiments were performed in the 1750–1850°C temperature range with holding time from 1 to 10min. Two pressure setups were used: one with pressure (75MPa) applied at 1000°C and the other with ultimate pressure applied at sintering temperature. Experimental data highlighted the fact that temperature and holding time have a different impact on grain growth and densification. Diffusion and migration mechanisms that promote grain growth were found to be strongly dependent on temperature, the latter being linked to pulsed current intensity. Conditions of pressure application suggest that the ultimate pressure applied at higher temperature increases densification by keeping small surface contact between particles. [Copyright &y& Elsevier]

The structure and electric conductivity of the fast oxide ion conductors Bi13(Mo,M)5O34, i.e. Bi[Bi12O14][(Mo,M)O4]5 with M=Li, Mg, Al, Si, Ge and V were investigated using X-ray powder diffraction experiments and AC impedance spectroscopy. The compounds of this original family are isostructural with Bi13Mo4VO34; they crystallize in the monoclinic system with the space group P2/c. The structures exhibit typical [Bi12O14]n columns developed along [010], surrounded by (Mo,M)O4 tetrahedra packed in layers parallel to (100) and (001), the electrical balance of the network being achieved by Bi atoms at the intersection of these planes. The syntheses, X-ray powder pattern analyses and conductivity measurements are reported; the best anionic conductor of the family is proved to be Bi[Bi12O14][(Mo0.933Al0.067)O4]5 with σ980 K=1.4×10−2 S cm−1. [Copyright &y& Elsevier]

New acridine derivatives have been prepared via Ullman condensation involving benzoxazole (5) and 2-bromo-benzoic acid. Linear products were obtained. The structure of oxazolo[4,5-b]acridine was determined by NMR spectroscopy. [ABSTRACT FROM AUTHOR]

The relaxor-type behavior, electrical polarization buildup, and switching in 0.92Pb(Zn(1/3)Nb(2/3))O(3)-0.08PbTiO(3) nanostructured ceramics with a grain size of approximately 20 nm is reported for the first time. This composition presents the highest-known piezoelectric coefficients, yet phase stability is an issue. Ceramics can only be obtained by the combination of mechanosynthesis and spark-plasma sintering. The results raise the possibility of using nanoscale, perovskite-relaxor-based morphotropic-phase-boundary materials for sensing and actuation in nanoelectromechanical systems.

Two new series of diaminoacridinic derivatives obtained from proflavine and N-(6-amino-3-acridinyl)acetamide were synthesised and assessed for their cytotoxic and antileishmanial activities. Two compounds, N-[6-(acetylamino)-3-acridinyl]acetamide and N-[6-(benzoylamino)-3-acridinyl]benzamide demonstrated highly specific antileishmanial properties against the intracellular amastigote form of the parasite. Structure-activity relationships established that the antiproliferative activity against human cells was greatly enhanced by the presence of a benzoylamino group in 6-mono-substituted acridines, while the presence of two acetylamino or benzoylamino groups in 3,6-di-substituted acridines strongly increased the specificity of the molecules for Leishmania parasite, suggesting that symmetric conformations could preferentially interfere with Leishmania metabolism.

(1,3-Benzothiazol-2-yl) amino-9-(10H)-acridinone derivatives were synthesized via a procedure based on the Ullman reaction and were assessed for their in vitro antileishmanial and anti-HIV activities. Two derivatives, 4-(6-nitro-benzothiazol-2-ylamino)-10H-acridin-9-one and 1-(6-amino-benzothiazol-2-ylamino)-10H-acridin-9-one, revealed a selective antileishmanial activity, mainly due to amastigote-specific toxicity. Results suggested that:the addition of a benzothiazole group on a parent amino-9-(10H)-acridinone ring could enhance antileishmanial abilities, the presence of a 6-amino-benzothiazole group on position 2 amino chain or a 6-nitro-benzothiazole group on position 4 amino chain was essential for specific anti-amastigote properties.

A series of tetrahydroacridines related to tacrine have been synthesized starting from 3-methylcyclohexananone, menthone, pulegone, carvone and dihydrocarvone (both racemic and chiral). In many cases, the yields and purity of the compounds have been improved by the use of a microwave oven. These compounds have been characterized by (1)H and (13)C NMR data. To establish their relative configuration, the structure of (1R,4R)-(+)-9-chloro-1-methyl-4-isopropyl-1,2,3,4-tetrahydroacridine (cis-10b), derived from (2S,5R)-(-)-menthone, has been determined by X-ray. The chemical shifts of cis-10b and trans-10b have been calculated at the GIAO/B3LYP/6-31G* level and compared successfully with the experimental data.

Single crystals of the title compound have been prepared hydrothermally. Vanadate tetrahedra and distorted oxovanadium octahedra form layers, linked by two independent Cu atoms located on inversion centres. Each Cu atom is surrounded by six O atoms, forming an octahedron distorted by Jahn-Teller elongation. One of the two independent interlayer spaces bridged by the Cu atoms is significantly more compact than the other.

Clustering of ammonium chloride salts was studied using an electrospray source to characterize the form, mono- vs. dihydrochloride, of organic compounds by mass spectrometry. This new way of taking advantage of cluster formation is applied to aminomethylacridines as their storage requires the synthesis of such derivatives. Both positive and negative cluster mass spectra were obtained and allowed the determination of the nature of the hydrochloride forms as the salt mass is straightforwardly derived from the mass of the cluster monomer, calculated from singly and multiply charged ion distributions. The identity of the counterion is confirmed from the mass of the ionic moieties in the clusters., (Copyright 2003 John Wiley & Sons, Ltd.)

9-Chloro and 9-amino-2-methoxyacridines bearing different substituents in position 7, as well as their corresponding unsubstituted dimeric and tetrameric complexes, were investigated for in vitro antiproliferative properties against Leishmania infantum compared to toxicity towards human monocytes. The results clearly confirmed that several compounds of the 2-methoxyacridine series, together with their corresponding dimeric and tetrameric derivatives, had strong in vitro antiparasitic properties. Antileishmanial activity was shown to depend on the nature of both 7- and 9-substituted groups in monoacridines, while it varied according to the nature of the 9-substituted group and the length of the linker among bis- and tetra-acridines. The effects of acridine derivatives on DNA synthesis raised the hypothesis that DNA metabolism constituted their main target in Leishmania promastigotes; however, secondary effects on other biochemical pathways, including protein and lipid metabolism, were observed, suggesting that acridine compounds could be considered multitarget drugs.

The phase transition from the low- (beta) to the high-temperature (alpha) form of acetonitrile, CH(3)CN, has been directly observed and studied on a unique single crystal. Both the beta and alpha structures have been determined at temperatures close to the transition temperature (206 K and 201 K), taking advantage of the hysteresis. A single crystal of the beta form was obtained for the first time.

The title compound, diammonium aqua-mu-carbonato-tri-mu-oxalato-dineodymium(III) hydrate, (NH(4))(2)[Nd(2)(CO(3))(C(2)O(4))(3)(H(2)O)].H(2)O, involving the two ligands oxalate and carbonate, has been prepared hydrothermally as single crystals. The Nd atoms form a tetranuclear unit across the inversion centre at (1/2, 1/2, 1/2). Starting from this tetranuclear unit, the oxalate ligands serve to develop a three-dimensional network. The carbonate group acts as a bis-chelating ligand to two Nd atoms, and is monodentate to a third Nd atom. The oxalate groups are all bis-chelating. The two independent Nd atoms are ninefold coordinated and the coordination polyhedron of these atoms is a distorted monocapped antiprism.

A single crystal of KVTeO(5), potassium vanadium tellurite, has been grown. The present structure determination has been conducted together with the refinement of the NaVTeO(5) homologue, sodium vanadium tellurite, for the sake of precise comparison. The network consists of [VTeO(5)](n) ribbons built up by VO(4) tetrahedra linking centrosymmetric Te(2)O(6) groups and stacked along the [010] direction; the alkali cations are intercalated in between. The Te(IV) atom exhibits a typical one-sided coordination number (CN) of 4, completed by a lone pair, which forms a distorted triangular bipyramid with the four O atoms.

6-Nitro- and 6-amino-benzothiazoles bearing different chains in position 2 and their corresponding anthranilic acid derivatives were investigated for their in vitro antiparasitic properties against parasites of the species Leishmania infantum and Trichomonas vaginalis compared to their toxicity towards human monocytes. Biological investigations established that the antiprotozoal properties depended greatly on the chemical structure of the position 2 substitution-bearing group. Compound C1, 2-[(2-chloro-benzothiazol-6-yl) amino] benzoic acid, demonstrated an interesting antiproliferative activity towards parasites of the species T. vaginalis, while compound C11, 2-([2-[(2-hydroxyethyl) amino]-benzothiazol-6-yl] amino) benzoic acid, exhibited a promising activity against parasites of the species L. infantum in their intracellular amastigote form. Additional experiments established that compound C11, which was poorly toxic against the promastigote and the extracellular amastigote forms of the parasite, could improve host-protective mechanisms against Leishmania by preventing parasite internalization by macrophages and stimulating NO production, by means of a mechanism synergistically enhanced by the presence of gamma interferon.

This paper presents structural studies on crystalline and liquid AsCl(3), performed using X-ray diffraction (XRD) and wide-angle X-ray scattering (WAXS) in the 176-250 K temperature range and at 295 K for the crystalline and liquid samples, respectively. The XRD results, collected using a single-crystal diffractometer, show that AsCl(3) crystallizes in the orthorhombic system with P2(1)2(1)2(1) space group and the unit cell parameters a = 9.475(3) A, b = 11.331(2) A, and c = 4.2964(8) A at 221 K. This structure is stable in the temperature range 176-243 K. Above the melting point, at 257 K, transition to the liquid state is observed. The WAXS data were recorded up to a maximum scattering vector K(max) = 16 A(-1) and then converted to real space by the sine Fourier transform, yielding to the reduced radial distribution function (RRDF). For a series of models, based on the crystalline AsCl(3) structure, the intensity and RRDF functions have been computed and compared with the experimental data. These simulations indicate that the model consisting of six AsCl(3) molecules, arranged along the y axis, accounts satisfactorily for the experimental observation. The results of the structure analysis in both crystalline and liquid states are discussed in relation to the influence of the As lone electron pair.

A single crystal of MoVAlO7, vanadium aluminium molybdate, has been grown. The present structure determination is more precise than a previous powder-pattern investigation [Knorr, Jacubus, Dabrowska & Kurzawa (1998). Eur. J. Solid State Inorg. Chem. 35, 519-530]. A three-dimensional [MoAlO6](3n-)n network surrounds infinite strings of [VO]3+ groups [V-O = 1.586 (4) A] lying in the mirror planes.