Within-plant isoprene oxidation confirmed by direct emissions of oxidation products methyl vinyl ketone and methacrolein

Isoprene is emitted from many terrestrial plants at high rates, accounting for an estimated 1/3 of annual global volatile organic compound emissions from all anthropogenic and biogenic sources combined. Through rapid photooxidation reactions in the atmosphere, isoprene is converted to a variety of oxidized hydrocarbons, providing higher order reactants for the production of organic nitrates and tropospheric ozone, reducing the availability of oxidants for the breakdown of radiatively active trace gases such as methane, and potentially producing hygroscopic particles that act as effective cloud condensation nuclei. However, the functional basis for plant production of isoprene remains elusive. It has been hypothesized that in the cell isoprene mitigates oxidative damage during the stress-induced accumulation of reactive oxygen species (ROS), but the products of isoprene-ROS reactions in plants have not been detected. Using pyruvate-2-13C leaf and branch feeding and individual branch and whole mesocosm flux studies, we present evidence that isoprene (i) is oxidized to methyl vinyl ketone and methacrolein (iox) in leaves and that iox/i emission ratios increase with temperature, possibly due to an increase in ROS production under high temperature and light stress. In a primary rainforest in Amazonia, we inferred significant in plant isoprene oxidation (despite the strong masking effect of simultaneous atmospheric oxidation), from its influence on the vertical distribution of iox uptake fluxes, which were shifted to low isoprene emitting regions of the canopy. These observations suggest that carbon investment in isoprene production is larger than that inferred from emissions alone and that models of tropospheric chemistry and biotachemistryclimate interactions should incorporate isoprene oxidation within both the biosphere and the atmosphere with potential implications for better understanding both the oxidizing power of the troposphere and forest response to climate change.

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.

Preparation and characterization of poly(vinyl butyral)-polyaniline-montmorillonite nanocomposites

Poly(vinyl butyral)-polyaniline-sodium montmorillonite nanocomposites were prepared via polymerization of aniline between clay mineral platelets at two different pH levels (2.0 and 5.0), followed by dispersion of the polyaniline-sodium montmorillonite nanocomposite in a poly(vinyl butyral) solution. A comparison was made of the effect of the pH levels and the polyaniline-sodium montmorillonite nanocomposite precursor on the final structures of the poly(vinyl butyral) nanocomposites and their electrical conductivities. X-ray diffraction patterns revealed the formation of nanocomposites at both pH levels. UV-Vis spectra indicated that the polyaniline formed at both pH levels was conductive, with the UV-Vis spectra presenting a band at 420 nm corresponding to the polaronic form and the beginning of a new band at 600 nm indicating the presence of polaronic segments. FTIR spectra revealed the peaks of the groups present in polyaniline and poly(vinyl butyral) nanocomposites. The electrical conductivities of the polyaniline and poly(vinyl butyral) nanocomposites prepared at pH 2.0 were lower than those of the same nanocomposites prepared at pH 5.0, probably due to the lower formation of polyaniline chains in a more acidic dispersion and to the final configuration of polyaniline in the nanocomposites.

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.

Credneramides A and B: Neuromodulatory Phenethylamine and Isopentylamine Derivatives of a Vinyl Chloride-Containing Fatty Acid from cf. Trichodesmium sp nov.

Credneramides A (1) and B (2), two vinyl chloride-containing metabolites, were isolated from a Papua New Guinea collection of cf. Trichodesmium sp. nov. and expand a recently described class of vinyl chloride-containing natural products. The precursor fatty acid, credneric acid (3), was isolated from both the aqueous and organic fractions of the parent fraction as well as from another geographically and phylogenetically distinct cyanobacterial collection (Panama). Credneramides A and B inhibited spontaneous calcium oscillations in murine cerebrocortical neurons at low micro-molar concentrations (1, IC50 4.0 mu M; 2, IC50 3.8 mu M).

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.

Experimental analyses of the poly(vinyl chloride) foams' mechanical anisotropic behavior

Assessing a full set of mechanical properties is a rather complicate task in the case of foams, especially if material models must be calibrated with these results. Many issues, for example anisotropy and heterogeneity, influence the mechanical behavior. This article shows through experimental analyses how the microstructure affects different experimental setups and it also quantifies the degree of anisotropy of a poly(vinyl chloride) foam. Monotonic and cyclic experimental tests were carried out using standard compression specimens and non-standard tensile specimens. Results are complemented and compared with the aid of a digital image correlation technique and scanning electron microscopy analyses. Mechanical properties (e.g., elastic and plastic Poisson's ratios) are evaluated for compression and tensile tests, for two different material directions (normal and in-plane). The material is found to be transversely isotropic. Differences in the results of the mechanical properties can be as high as 100%, or even more depending on the technique used and the loading direction. Also, the experimental analyses show how the material's microstructure behavior, like the evolution of the herein identified yield fronts and a spring back phenomenon, can influence the phenomenological response and the failure mechanisms as well as the hardening curves. POLYM. ENG. SCI., 52:2654-2663, 2012. (C) 2012 Society of Plastics Engineers

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]