Luminescence properties of the TRIMEB inclusion compound of a europium tris-beta-diketonate

The adduct TRIMEB:Eu(BTA)(3)center dot 2H(2)O was prepared and primarily characterized by photoluminescence (PL), and compared with free Eu(BTA)(3)center dot 2H(2)O. Both spectra show the Eu3+ ion emission, with subtle differences between lines for the free and encapsulated complex. The temperature dependence and chemical stability were studied, taking into account (in the latter case) the PL changes with time. The use of this new material as the emissive layer in OLEDs was tested by its successful incorporation into a device, using a conductive polymer as host. The use of the TRIMEB adduct increased the stability of the device (as compared with the free Eu complex). (C) 2008 Elsevier B.V. All rights reserved.

EMERGENT CONDITIONAL RELATIONS IN A GO/NO-GO PROCEDURE: FIGURE-GROUND AND STIMULUS-POSITION COMPOUND RELATIONS

Past research has demonstrated emergent conditional relations using a go/no-go procedure with pairs of figures displayed side-by-side on a computer screen. The present Study sought to extend applications Of this procedure. In Experiment, 1, we evaluated whether emergent conditional relations Could be demonstrated when two-component stimuli were displayed in figure-ground relationships-abstract figures displayed on backgrounds of different colors. Five normal)), capable adults participated. During training, each two-component stimulus Was presented successively. Responses emitted in the presence of some Stimulus pairs (A1B1, A2B2, A3B3, B1C1, B2C2 and B3C3) were reinforced, whereas responses emitted in the presence of other pairs (A1B2, A1B3, A2B1, A2B3, A3B1, A3B2, B1C2, B1C3, B2C1, B2C3, B3C1 and B3C2) were not. During tests, new configurations (AC and CA) were presented, thus emulating structurally the matching-to-sample tests employed in typical equivalence Studies. All participants showed emergent relations consistent with stimulus equivalence during testing. In Experiment 2, we systematically replicated the procedures with Stimulus compounds consisting Of four figures (A1, A2, C1 and C2) and two locations (left - B1 and right - 132). A,11 6 normally capable adults exhibited emergent stimulus-stimulus relations. Together, these experiments show that the go/no-go procedure is a potentially useful alternative for Studying emergent. conditional relations when matching-to-sample is procedurally cumbersome or impossible to use.

Structure and antimycobacterial activity of the novel organometallic [Pd(C-bzan)(SCN)(dppp)] compound

The organometallic compound [Pd(C-bzan)(SCN)(dppp)] {bzan = N-benzylideneaniline, dppp = 1,3-bis(diphenylphosphino)propane} was synthesized and characterized by elemental analyses, infrared and H-1 and P-31(H-1) NMR spectroscopies. The crystal and molecular structures of the title complex were determined by single-crystal X-ray diffraction techniques. In vitro antimycobacterial evaluation demonstrated that the compound [Pd(C-bzan)(SCN)(dppp)] displayed a MIC of 5.15 mu M, which is superior than those values found for some commonly used anti-TB drugs and other Pd(II) complexes. (C) 2012 Elsevier B.V. All rights reserved.

Grain size effect on the structural and dielectric properties of Pb0.85La0.15TiO3 ferroelectric ceramic compound

This paper presents a study of the influence of particle size on the structural and dielectric properties of Pb0.85La0.15TiO3 (PLT15) ferroelectric ceramic samples. The samples were prepared with average grain size of 1.69 +/- 0.08 mu m and 146 +/- 8 nm using, respectively, conventional and spark plasma sintering techniques. A decrease in the tetragonality degree as the crystallite size decreased was explained by an internal stress caused by the existence of a large amount of grain boundaries. The local structure exhibited no significant modification and the dielectric measurements showed a diffuse phase transition and a reduction in the permittivity magnitude at T-m as the average grain size decreased. The nanostructured ceramic sample prepared at a relatively lower temperature and sintering time presented a dielectric constant value of approximately 2000 at room temperature. (c) 2012 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

Obtaining NiAl intermetallic compound using different milling devices

NiAl intermetallic compound was synthesized by mechanical alloying technique in planetary and attritor mills. The starting powders consisted of elemental mixtures of Ni and Al at Ni50Al50(at%) composition. In the planetary mill, compound formation occurred gradually during mechanical alloying, while the occurrence of a mechanically induced self-propagating reaction (MSR) can be suggested in the attritor mill. The NiAl obtained in both mill types was partially disordered with long-range order parameter not inferior to 0.66. Quantitative phase analysis using the Rietveld method was performed in as-milled samples, and this method was also employed to estimate changes in crystallite size and lattice strain of the NiAl produced during mechanical alloying. (C) 2011 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.

Properties of nanoparticles prepared from NdFeB-based compound for magnetic hyperthermia application

Nanoparticles were prepared from a NdFeB-based alloy using the hydrogen decrepitation process together with high-energy ball milling and tested as heating agent for magnetic hyperthermia. In the milling time range evaluated (up to 10 h), the magnetic moment per mass at H = 1.59 MA m(-1) is superior than 70 A m(2) kg(-1); however, the intrinsic coercivity might be inferior than 20 kA m(-1). The material presents both ferromagnetic and superparamagnetic particles constituted by a mixture of phases due to the incomplete disproportionation reaction of Nd2Fe14BHx during milling. Solutions prepared with deionized water and magnetic particles exposed to an AC magnetic field (H-max similar to 3.7 kA m(-1) and f = 228 kHz) exhibited 26 K <= Delta T-max <= 44 K with a maximum estimated specific absorption rate (SAR) of 225 W kg(-1). For the pure magnetic material milled for the longest period of time (10 h), the SAR was estimated as similar to 2500 W kg(-1). In vitro tests indicated that the powders have acceptable cytotoxicity over a wide range of concentration (0.1-100 mu g ml(-1)) due to the coating applied during milling.

Antibacterial compound from the endophytic fungus Phomopsis longicolla isolated from the tropical red seaweed Bostrychia radicans

Endophytic fungi isolated from the red seaweed Bostrychia radicans were studied to identify their molecularly diverse and biologically active natural chemical products. According to 28S ribosomal DNA-based identification, the strain named C81 was 98% identical to Phomopsis longicolla. This strain was cultivated in solid rice medium and produced three major metabolites identified as 18-deoxycytochalasin H (1), mycophenolic acid (2), and dicerandrol C (3). The chemical structures of these compounds were elucidated by 1D and 2D nuclear magnetic resonance as well as by mass spectrometry. Dicerandrol C had significant antimicrobial activity against Staphylococcus aureus (ATCC 6538) and Staphylococcus saprophyticus (ATCC 15305), with minimum inhibitory concentrations of 1 and 2 mu g ml(-1) (1.33 and 2.66 mu M), respectively. These results show the presence of promising metabolites and indicate that these natural products should be considered in the development of new antibiotics.

Polarization effect on the two-photon absorption of a chiral compound

In this report, we investigate the polarization effect (linear, elliptical and circular) on the two-photon absorption (2PA) properties of a chiral compound based in azoaromatic moieties using the femtosecond Z-scan technique with low repetition rate and low pulse energy. We observed a strong 2PA modulation between 800 nm and 960 nm as a function the polarization changes from linear through elliptical to circular. Such results were interpreted employing the sum-over-essential states approach, which allowed us to model the 2PA circular-linear dichroism effect and to identifier the overlapping of the excited electronic states responsible by the 2PA allowed band. (C) 2012 Optical Society of America

Effects of the antimycobacterial compound 2-phenoxy-1-phenylethanone on rat hepatocytes and formation of metabolites

Context: Neolignans are usually dimers formed by oxidative coupling of allyl and propenyl phenols, and the neolignan analogue, 2-phenoxy-1-phenylethanone (LS-2) is a promising antimycobacterial compound showing very weak cytotoxicity in mammalian cells and lack of acute toxicity in murine models. Objectives: To investigate the mechanism of action of LS-2 in rat hepatocytes by evaluating the activity levels of enzymes related to oxidation status and drug-metabolizing activity. Materials and methods: Hepatocytes were treated with LS-2 from 0.05 up to 1 mM, for 24 and 48 h, and reduced glutathione (GSH), lipid peroxidation and cytochrome P450 enzyme (CYP450) activity were assayed. A homologous series of phenoxazone ethers were used as substrates to measure the enzymatic profile. The biotransformation of LS-2 was studied in hepatocytes by gas chromatography-mass spectrometry (GC-MS) for detection and analysis of possible metabolites. Results: Hepatocytes treated with LS-2 up to 1 mM for 24 or 48 h did not induce the formation of GSH and lipid peroxidation. O-Dealkylation activities of the isoenzymes CYP4501A1, CYP4501A2, CYP4502B1 and CYP4502B2 were also not detected in the hepatocytes treated with LS-2 for 24 or 48 h. Discussion and conclusion: The results indicate that LS-2 or its two detected metabolites, 2-phenoxy-1-phenylethanol and 2,4-(2-hydroxy-2-phenylethoxy) phenol, are not cytotoxic to rat hepatocytes. These compounds maintain a balance between the production of pro-oxidant agents and their respective antioxidant systems. The data show that enzymes related to oxidation status and drug-metabolizing activities are not involved in the mechanism of action of LS-2.

Spin-polarized transport in II-VI diluted magnetic semiconductors superlattices

We studied the spin-polarized charge densities in II-VI-based diluted magnetic superlattices formed of p-doped ZnTe:Mg/ZnTe:TM/ZnTe:Mg non-magnetic/magnetic/non-magnetic layers, with TM standing for transition metal. The calculations were performed within a self-consistent k.p method, in which are also taken into account the exchange correlation effects in the local density approximation. Our results show a limit for the width of the non-magnetic layer for which the difference between the opposite spin charge densities is maximized, indicating the best conditions to obtain full polarization by varying the TM content. We also discuss these effects in the calculated photoluminescence spectra. Our findings point to the possibility of engineering the spin-polarized charge distribution by varying the widths of the magnetic and non-magnetic layers and/or varying the TM concentration in the magnetic layers, thus providing a guide for future experiments. (c) 2012 Elsevier B.V. All rights reserved.

Superconductivity at 9.5 K in the Ti2GeC compound

We report on the investigation of the Ti2GeC properties by X-ray diffraction, magnetic and electrical resistivity measurements. Polycrystalline samples of Ti2GeC with nominal compositions were prepared by solid state reaction. X-ray powder patterns suggest that all peaks can be indexed with the hexagonal phase of Cr2AlC prototype. The temperature dependence of both electrical resistivity and magnetization indicate a bulk type-II superconductivity at 9.5 K. Magnetoresistive data suggest an upper critical field of B-c2 similar to 8.1 T and coherence length similar to 61 A degrees . Furthermore, the results highlight the highest critical temperature reported up to now for an H-phase.

Interstitial doping induced superconductivity at 15.3 K in Nb5Ge3 compound

It is reported superconductivity in Nb5Ge3C0.3, an interstitial carbide compound. The temperature dependence of the electrical resistivity, ac-susceptibility, and heat capacity (HC) indicate that a bulk type-II superconductivity appears at T-C - 15.3 K. Magneto-resistance measurements suggest an upper critical field of B-C2 similar to 10.6 T and a coherence length of xi similar to 55 angstrom at zero temperature. Neutron diffraction analyzes locate the carbon atoms at the interstitial 2b site of the Mn5Si3 type-structure. Heat capacity data below T-C are well described by BCS theory. The size of the jump at T-C is in good agreement with the superconducting volume fraction observed in susceptibility measurements. A Debye temperature and Sommerfeld constant were also extracted from heat capacity data as 343 K and 34 mJ/mol K-2, respectively. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4730611]

Propolis Standardized Extract (EPP-AF (R)), an Innovative Chemically and Biologically Reproducible Pharmaceutical Compound for Treating Wounds

The aim of this study was to develop a formulation, containing the propolis standardized extract (EPP-AF (R)), which can assist in the healing of skin lesions. To achieve this objective the antimicrobial activity and chemical composition of the propolis extract was determined. The final product was subjected to in vitro and in vivo pre-clinical evaluation. The broth macrodi-lution method was used to determine the antimicrobial activity of the extracts and formulations against the microorganisms most commonly found in burns, Pseudomonas aeruginosa, Klebsiella pneumoniae, Escherichia coli, Staphylococcus aureus and Staphylococcus epidermidis. Wistar rats with puncture wounded skin were used to evaluate the wound healing properties of propolis. The results of chemical and biological characterization demonstrated the batch-to-batch reproducibility of the standardized extract which is an unprecedented result. The antimicrobial and wound healing activity of the pharmaceutical studied showed the best results when samples contain 3.6% propolis, suggesting that this is the most promising composition.

Synthesis and characterization of a diruthenium(II,III)-ketoprofen compound and study of the in vitro effects on CRC cells in comparison to the naproxen and ibuprofen derivatives

A new diruthenium(II,III) complex, of formula [Ru2Cl(ket)(4)], Ruket, containing the non-steroidal anti-inflammatory drug ketoprofen was synthesized and mainly characterized by electrospray ionization mass spectrometry (ESI-MS), UV-Vis-IR electronic spectroscopy and FTIR and Raman vibrational spectroscopies. The four drug-carboxylato bridging ligands stabilize a Ru-2(II,III) mixed valent core in a paddlewheel type structure as confirmed by ESI mass spectra, electronic and vibrational spectroscopies and magnetic measurements. Ruket and the analogous compounds containing ibuprofen, Ruibp, and naproxen, Runpx, were tested for the biological effects in the human colon carcinoma cells HT-29 and Caco-2 expressing high and low levels of COX-2 respectively. All compounds only weakly affected the proliferation of the colorectal cancer cells HT-29 and Caco-2, and similarly only partially inhibited the production/activity of MMP-2 and MMP-9 by HT-29 cells, suggesting that COX-2 inhibition by these drugs can only partially be involved in the pharmacological effects of these derivatives. (c) 2012 Elsevier Ltd. All rights reserved.

Study of the vertical transport in p-doped superlattices based on group III-V semiconductors

The electrical conductivity σ has been calculated for p-doped GaAs/Al0.3Ga0.7As and cubic GaN/Al0.3Ga0.7N thin superlattices (SLs). The calculations are done within a self-consistent approach to the k → ⋅ p → theory by means of a full six-band Luttinger-Kohn Hamiltonian, together with the Poisson equation in a plane wave representation, including exchange correlation effects within the local density approximation. It was also assumed that transport in the SL occurs through extended minibands states for each carrier, and the conductivity is calculated at zero temperature and in low-field ohmic limits by the quasi-chemical Boltzmann kinetic equation. It was shown that the particular minibands structure of the p-doped SLs leads to a plateau-like behavior in the conductivity as a function of the donor concentration and/or the Fermi level energy. In addition, it is shown that the Coulomb and exchange-correlation effects play an important role in these systems, since they determine the bending potential.