Flavonoids in phylloclades discriminate endemic Semele androgyna chemotypes from Madeira

Thirty-five randomly-collected Semele androgyna Kunth samples were screened by RP-HPLC for their phenolic composition. Fraction analysis allowed the detection of 17 different compounds. According to their retention times and UV spectra obtained by diode array analysis, these phenolics represent three classes: phenolic acids, flavones and flavonols. Co-chromatography with specific standards enabled identification of quercetin, rutin and quercitrin in Semele tissues for the first time. Polymorphism based on phenolic composition was evaluated using multivariate analysis and showed four distinct S. androgyna clusters. This polymorphism was not associated with morphological diversity or different in ambient light intensities. Biochemical differentiation is thus present in this species. The application of multivariate analysis techniques to RP-HPLC data has allowed the classification of samples into two groups, previously proposed on the basis of morphological and cytotaxonomical information. Therefore, the use of phenolics as chemotaxonomic markers in Semele is highly recommended because of its diagnostic value, even at a subspecies level. Discriminant canonical analysis and Mahalanobis distances confirmed these clusters as recognisable chemosystematic units. However, these units do not support the separation of S. pterygophora.The Portuguese Foundation for Science and Technology (FCT) funded this work through the Centre of Macaronesian Studies (CEM). The authors are grateful to the Madeiran Centre of Science and Technology (CITMA), the Berardo Foundation and European Social Funding for financial assistance given during execution of this work. The assistance rendered by Mr Rogério Correia during field collection is gratefully acknowledged.info:eu-repo/semantics/publishedVersio

Li1.5La1.5MO6 (M = W6+, Te6+) as a new series of lithium-rich double perovskites for all-solid-state lithium-ion batteries

Solid-state batteries are a proposed route to safely achieving high energy densities, yet this architecture faces challenges arising from interfacial issues between the electrode and solid electrolyte. Here we develop a novel family of double perovskites, Li1.5La1.5MO6 (M = W6+, Te6+), where an uncommon lithium-ion distribution enables macroscopic ion diffusion and tailored design of the composition allows us to switch functionality to either a negative electrode or a solid electrolyte. Introduction of tungsten allows reversible lithium-ion intercalation below 1 V, enabling application as an anode (initial specific capacity >200 mAh g-1 with remarkably low volume change of ∼0.2%). By contrast, substitution of tungsten with tellurium induces redox stability, directing the functionality of the perovskite towards a solid-state electrolyte with electrochemical stability up to 5 V and a low activation energy barrier (<0.2 eV) for microscopic lithium-ion diffusion. Characterisation across multiple length- and time-scales allows interrogation of the structure-property relationships in these materials and preliminary examination of a solid-state cell employing both compositions suggests lattice-matching avenues show promise for all-solid-state batteries

Structural, electrical conductivity and dielectric relaxation behavior of LiHf2(PO4)3 ceramic powders

Lithium hafnium phosphate LiHf2(PO4)3 (LHP) was synthesized via solid-state synthesis technique. The sintering behavior, structure, and phase composition of the as-prepared sample was analyzed using X-ray diffraction (XRD) characterization technique. The XRD-Rietveld refinement analysis showed that after sintering at low temperatures 500 to 1000 °C, it exhibited various secondary phases. However, a single phase was observed as the sintering temperature increases from 1100 to 1200 °C. LHP sintered at 1100 °C produced real features of sodium superionic conductor type (NASICON-type) with hexagonal crystal axis indicating R-3c space group. The electrical properties were studied using impedance spectroscopy technique. Frequency and temperature dependence behavior of conductivity (ac and dc) and dielectric permittivity were studied. The results obtained describes the conduction mechanism in the system. Electric modulus formalism was performed to investigate the relaxation behavior which showed that as measuring temperature increases, the relaxation frequency increases whereas relaxation time decreases. This behavior explains the hopping mechanism of the charge carriers in the system. Likewise, the correlated barrier hopping model elucidates the dominant hopping mechanism

Elevation of the Yields of Very Long Chain Polyunsaturated Fatty Acids via Minimal Codon Optimization of Two Key Biosynthetic Enzymes

Eicosapentaenoic acid (EPA, 20:5Δ5,8,11,14,17) and Docosahexaenoic acid (DHA, 22:6Δ4,7,10,13,16,19) are nutritionally beneficial to human health. Transgenic production of EPA and DHA in oilseed crops by transferring genes originating from lower eukaryotes, such as microalgae and fungi, has been attempted in recent years. However, the low yield of EPA and DHA produced in these transgenic crops is a major hurdle for the commercialization of these transgenics. Many factors can negatively affect transgene expression, leading to a low level of converted fatty acid products. Among these the codon bias between the transgene donor and the host crop is one of the major contributing factors. Therefore, we carried out codon optimization of a fatty acid delta-6 desaturase gene PinD6 from the fungus Phytophthora infestans, and a delta-9 elongase gene, IgASE1 from the microalga Isochrysis galbana for expression in Saccharomyces cerevisiae and Arabidopsis respectively. These are the two key genes encoding enzymes for driving the first catalytic steps in the Δ6 desaturation/ Δ6 elongation and the Δ9 elongation/Δ8 desaturation pathways for EPA/DHA biosynthesis. Hence expression levels of these two genes are important in determining the final yield of EPA/DHA. Via PCR-based mutagenesis we optimized the least preferred codons within the first 16 codons at their N-termini, as well as the most biased CGC codons (coding for arginine) within the entire sequences of both genes. An expression study showed that transgenic Arabidopsis plants harbouring the codon-optimized IgASE1 contained 64% more elongated fatty acid products than plants expressing the native IgASE1 sequence, whilst Saccharomyces cerevisiae expressing the codon optimized PinD6 yielded 20 times more desaturated products than yeast expressing wild-type (WT) PinD6. Thus the codon optimization strategy we developed here offers a simple, effective and low-cost alternative to whole gene synthesis for high expression of foreign genes in yeast and Arabidopsis

Structural and electrochemical characterization of Ce_0.85Ca _0.05Sm_0.1O_1.9 oxide ion electrolyte with Sr-doped LaMnO₃ and SmCoO₃ cathodes

This paper reports on the electrochemical properties and chemical stability of a recently developed Ca2+ and Sm3+-doped oxide ion conducting electrolyte, Ce0.85Ca0.05Sm0.1O 1.9 (CCS), employed in an intermediate temperature solid oxide fuel cell (IT-SOFC) using conventional Sm0.5Sr0.5CoO 3 (SSC) and La0.8Sr0.2MnO3 (LSM) cathodes in air at elevated temperatures. The materials were prepared by conventional solid-state reactions using their corresponding metal oxides and salts in the temperature range of 1,200-1,450 °C in air. Powder X-ray diffraction (PXRD) and impedance spectroscopy were employed for phase formation, chemical compatibility, and electrochemical characterization. PXRD studies on 1:1 weight ratio of heat-treated (1,000 °C for 3 days) mixtures of SSC or LSM and CCS revealed the presence of fluorite-type and perovskite-like phases. The area-specific resistance (ASR) value in air was lower for SSC cathodes (4.3-0.15 Ω cm2) compared to those of LSM (407-11 Ω cm2) over the investigated temperature range of 600-800 °C. As expected, a significant increase in ASR was observed in Ar as compared to air.</p

Metathetic room temperature preparation and characterization of scheelite-type ABO₄ (A = Ca, Sr, Ba, Pb; B = Mo, W) powders

Scheelite-type ABO4 (A = Ca, Sr, Ba, Pb; B = Mo, W) powders of the shape of small spheres (except BaBO4: needles) were prepared at room temperature by metathetic reactions using aqueous solutions of alkaline or lead chloride, and sodium molybdates or tungstates. The reaction is completed within a minute. The particle size as determined by SEM is of the order of several micrometers. Impedance measurements show activation energies of 0.40 and 0.62eV for SrWO4 and PbWO4, respectively. EMF measurements indicate ionic transport with an average transference number of 0.86-0.95 over the oxygen partial pressure range 10-4 to 10 -19atm in the temperature range 600-850°C.</p

First Total H +

Garnet-type Li 5+xBa xLa 3-xNb 2O 12 (x = 0, 0.5, 1) was prepared using a ceramic method, and H +/Li + ion exchange was performed at room temperature using organic acids, such as CH 3COOH and C 6H 5COOH, as proton sources. Thermogravimetric analysis showed that H +/Li + ion exchange was nearly (100%) completed using the x = 0 member with CH 3COOH, while it proceeded to about 40% for x = 0.5 and 13% for x = 1. In C 6H 5COOH, proton exchange proceeded to about 82% for x = 0, ∼40% for x = 0.5, and ∼25% for x = 1. Similar proton-exchange trends were reported in H 2O, where ion exchange occurs more readily for garnets with lower Li content in Li 5+xBa xLa 3-xNb 2O 12, that is, when excess Li ions preferentially reside in the tetrahedral sites of the garnet structure.</p