Competitive evolution of the fine contrast modulation and CuPt ordering in InGaP/GaAs layers

We use transmission electron microscopy to characterize the morphology of InGaP epitaxial layers grown by metal‐organic vapor‐phase epitaxy over misoriented GaAs (001) substrates, with a cutoff angle in a range from 0° to 25°. The occurrence of phase separation and CuPt‐type ordered superstructures has been observed. The most ordered configuration has been found to appear in layers grown on 2° off substrates, and the strength of order decreases with increasing the misorientation angle beyond α=2°. Conversely, whereas the phase separation is less evident in the layer grown at 2°, the sample grown with a misorientation of 25° exhibits the most phase separated configuration. The completion between these two phenomena is discussed depending on the misorientation angle

Characterization of a putative grapevine Zn transporter, VvZIP3, suggests its involvement in early reproductive development in Vitis vinifera L

Gonzalez, E (reprint author), Univ Talca, Inst Biol Vegetal & Biotecnol, Talca, Chile.Background: Zinc (Zn) deficiency is one of the most widespread mineral nutritional problems that affect normal development in plants. Because Zn cannot passively diffuse across cell membranes, it must be transported into intracellular compartments for all biological processes where Zn is required. Several members of the Zinc-regulated transporters, Iron-regulated transporter-like Protein (ZIP) gene family have been characterized in plants, and have shown to be involved in metal uptake and transport. This study describes the first putative Zn transporter in grapevine. Unravelling its function may explain an important symptom of Zn deficiency in grapevines, which is the production of clusters with fewer and usually smaller berries than normal. Results: We identified and characterized a putative Zn transporter from berries of Vitis vinifera L., named VvZIP3. Compared to other members of the ZIP family identified in the Vitis vinifera L. genome, VvZIP3 is mainly expressed in reproductive tissue - specifically in developing flowers - which correlates with the high Zn accumulation in these organs. Contrary to this, the low expression of VvZIP3 in parthenocarpic berries shows a relationship with the lower Zn accumulation in this tissue than in normal seeded berries where its expression is induced by Zn. The predicted protein sequence indicates strong similarity with several members of the ZIP family from Arabidopsis thaliana and other species. Moreover, VvZIP3 complemented the growth defect of a yeast Zn-uptake mutant, ZHY3, and is localized in the plasma membrane of plant cells, suggesting that VvZIP3 has the function of a Zn uptake transporter. Conclusions: Our results suggest that VvZIP3 encodes a putative plasma membrane Zn transporter protein member of the ZIP gene family that might play a role in Zn uptake and distribution during the early reproductive development in Vitis vinifera L., indicating that the availability of this micronutrient may be relevant for reproductive development

Review: Metastable materials accessed under moderate pressure conditions (P <= 3.5 GPa) in a piston-Cylinder press

In this review, we describe different families of metastable materials, some of them with relevant technological applications, which can be stabilized at moderate pressures 2-3.5 GPa in a piston-cylinder press. The synthesis of some of these systems had been previously reported under higher hydrostatic pressures (6-10 GPa), but can be accessed under milder conditions in combination with reactive precursors prepared by soft-chemistry techniques. These systems include perovskites with transition metals in unusual oxidation states (e.g., RNiO_(3) with Ni^(3+), R = rare earths); double perovskites such as RCu_(3)Mn_(4)O_(12) with Jahn-Teller Cu^(2+) ions at A sites, pyrochlores derived from Tl_(2)Mn_(2)O_(7) with colossal magnetoresistance, pnictide skutterudites M_(x)Co_(4)Sb_(12) (M = La, Yb, Ce, Sr, K) with thermoelectric properties, or metal hydrides Mg_(2)MH_(x) (M = Fe, Co, Ni) and AM_(g)H_(3) (A: alkali metals) with applications in hydrogen storage. The availability of substantial amounts of sample (0.5-1.5 g) allows a complete characterization of the properties of interest, including magnetic, transport, thermoelectric properties and so on, and the structural characterization by neutron or synchrotron X-ray diffraction techniques

Estudo comparativo da atividade anti-helmíntica de óleos essenciais de Piper sobre o nematoide parasita de ovinos, Haemonchus contortus.

20 a 22 nov. SBOE. e-Pôster. Ref. 68

Avaliação do óleo essencial de Schinus lentiscifolius frente a eclodibilidade de ovos do parasita gastrointestinal Haemonchus contortus.

Haemonchus contortus é o nematódeo de maior prevalência na ovinocultura e devido ao seu hábito hematófago é responsável pelas maiores perdas no que diz respeito à essa atividade

Thermal expansion and rattling behavior of Gd-filled Co_(4)Sb_(12) skutterudite determined by high-resolution synchrotron x-ray diffraction

In this work, Gd-filled skutterudite Gd_(x)Co_(4)Sb_(12) was prepared using one step method under high pressure in a piston-cylinder-based press at 3.5 GPa and moderate temperature of 800 degrees C. A detailed structural characterization was performed using synchrotron X-ray diffraction (SXRD), revealing a filling fraction of x = 0.033(2) and an average bond length of 3.3499(3) angstrom. The lattice thermal expansion accessed via temperature-dependent SXRD led to a precise determination of a Debye temperature of 322(3) K, from the fitting of the unit-cell volume expansion using the second order Gruneisen approximation. This parameter, when evaluated through the mean square displacements of Co and Sb, displayed a value of 265(2) K, meaning that the application of the harmonic Debye theory underestimates the Debye temperature in skutterudites. Regarding the Gd atom, its intrinsic disorder value was similar to 5x and similar to 25x higher than those of the Co and Sb, respectively, denoting that Gd has a strong rattling behavior with an Einstein temperature of theta(E) = 67(2) K. As a result, an ultra-low thermal conductivity of 0.89 W/m center dot K at 773 K was obtained, leading to a thermoelectric efficiency zT of 0.5 at 673 K

Structural evolution from neutron powder diffraction of nanostructured snte obtained by arc melting

Among chalcogenide thermoelectric materials, SnTe is an excellent candidate for intermediate temperature applications, in replacement of toxic PbTe. We have prepared pure polycrystalline SnTe by arc melting, and investigated the structural evolution by temperature-dependent neutron powder diffraction (NPD) from room temperature up to 973 K. In this temperature range, the sample is cubic (space group Fm-3m) and shows considerably larger displacement parameters for Te than for Sn. The structural analysis allowed the determination of the Debye model parameters and provided information on the Sn-Te chemical bonds. SEM images show a conspicuous nanostructuration in layers below 30 nm thick, which contributes to the reduction of the thermal conductivity down to 2.5 W/m center dot K at 800 K. The SPS treatment seems to reduce the number of Sn vacancies, thus diminishing the carrier density and increasing the Seebeck coefficient, which reaches 60 mu V K^(-1) at 700 K, as well as the weighted mobility, almost doubled compared with that of the as-grown sample