Phase-selective growth of κ\kappa- vs β\beta-Ga2_2O3_3 and (Inx_xGa1−x_{1-x})2_2O3_3 by In-mediated metal exchange catalysis in plasma-assisted molecular beam epitaxy

Its piezo- and potentially ferroelectric properties make the metastable kappa polymorph of Ga$_2$O$_3$ an interesting material for multiple applications, while In-incorporation into any polymorphs of Ga$_2$O$_3$ allows to lower their bandgap. In this work, we provide a guideline to achieve single phase $\kappa$-, $\beta$-Ga$_2$O$_3$ as well as their (In$_x$Ga$_{1-x}$)$_2$O$_3$ alloys up to x = 0.14 and x = 0.17 respectively, using In-mediated metal exchange catalysis in plasma assisted molecular beam epitaxy (MEXCAT-MBE). The polymorph transition from $\kappa$ to $\beta$ is also addressed, highlighting the fundamental role played by the thermal stability of the $\kappa$-Ga$_2$O$_3$. Additionally, we also demonstrate the possibility to grow ($\bar{2}$01) $\beta$-Ga$_2$O$_3$ on top of $\alpha$-Al$_2$O$_3$ (0001) at temperatures at least 100 {\deg}C above those achievable with conventional non-catalyzed MBE, opening the road for increased crystal quality in heteroepitaxy. The role of the substrate, as well as strain and structural defects in the growth of $\kappa$-Ga$_2$O$_3$ is also investigated by growing simultaneously on three different materials: (i) $\alpha$-Al$_2$O$_3$ (0001), (ii) 20 nm of ($\bar{2}$01) $\beta$-Ga$_2$O$_3$ on $\alpha$-Al$_2$O$_3$ (0001) and (iii) ($\bar{2}$01) $\beta$-Ga$_2$O$_3$ single crystal.Comment: Main text: 7 pages, 4 figures; Supplementary: 6 pages, 9 figure

Refinement of Biomarker Pentosidine Methodology for use on Aging Birds

There is no reliable method for determining age for most species of long-lived birds. Recent success using the skin chemical pentosidine as a biomarker has shown promise as an aging tool for birds. Pentosidine levels have been determined only from the breast tissue of carcasses, and we sought to refine the procedure with respect to biopsy size and location for safe and effective use on living birds. We compared pentosidine concentrations in 4 skin-size samples (4, 6, 8, and 20-mm diameter biopsies) from the breast of black vulture (Coragyps atratus) carcasses. We also compared pentosidine levels from breast and patagial tissue to document potential differences among collection sites of deceased vultures (with unknown ages) and monk parakeets (Myiopsitta monachus; with actual, minimal, and unknown ages). Pentosidine concentrations (pmol pentosidine/mg collagen) were similar among the 4 sizes of vulture breast skin (P = 0.82). Pentosidine concentrations for the breast (x̄ = 8.9, SE = 0.55, n = 28) and patagium (x̄ = 8.9, SE = 0.51, n = 28) of vultures were similar, but in parakeets, pentosidine was higher in the breast (x̄ = 15.9, SE = 1.30, n = 105) than the patagium (x̄ = 11.5, SE = 1.10, n = 105). We made pentosidine-based age estimates for vultures and parakeets using a general age curve for wild birds. We also made vulture age estimates using plumage characteristics and a cormorant (Phalacrocorax auritus) age curve. Vulture pentosidine-based age estimates appear to correspond to plumage-based age estimates. Pentosidine-based age estimates for 88% of the known-aged parakeets (n = 17) were within 6 months of actual ages. Even though known ages were not available for all birds, we found a positive trend in pentosidine versus age for both species. We suggest that 6-mm diameter skin samples from the patagium of living vultures and other similar-sized birds will provide sufficient tissue for reliable age estimation and will not impair flight ability

Estudio y evaluación de organismos plagas y sus enemigos naturales del cultivo de amarantos en Argentina

Con el nombre de Amaranto se designa a numerosas especies del género Amaranthus, Familia Amarantaceae. Las especies cultivadas son herbáceas anuales de uso tanto hortícola como granífera. En la provincia de La Pampa al igual que en el resto del país, son escasos los antecedentes sobre organismos asociados al cultivo de amaranto, por tal motivo los objetivos de este trabajo fueron estudiar la entomofauna asociada a dicho cultivo. El trabajo se llevó a cabo durante la campaña 2006 - 07, en un lote del campo experimental de la Facultad de Agronomía de la UNLPam., ubicada sobre la Ruta Nacional W 35 en el Km. 334,10 km al norte de Santa Rosa (La Pampa). El ensayo siguió un diseño de bloques (N=4) con 18 tratamientos (variedades) por bloque. En cada tratamiento se seleccionaron 6 plantas al azar y se revisó mediante observación directa la planta completa. Los muestreos se realizaron semanalmente durante todo el ciclo del cultivo. La entomofauna fue variando en densidad en los diferentes estadios fenológicos del cultivo. Los ejemplares identificados se agruparon en diez órdenes que comprenden 21 familias y 23 géneros Los órdenes con el mayor número de familias fueron Coleóptera (6) y Hemiptera (4). Dentro del Orden Coleóptera las familias más representadas fueron Curculionidae y Coccinelidae; en Hemiptera la familia Pentatomidae. En estado de plántula la especie fitófaga con mayor densidad poblacional fue Acromyrmex striatus (Roger) (Hymenoptera: Formicidae). Durante los estados vegetativos las más abundantes fueron Epicauta adspersa (Klujj (Coleóptera: Meloidae), Nezara viridula (L) y Edessa meditabunda (F.) (Hemiptera: Pentatomidae), mientras que en los estados reproductivos predominó la población de arañuela roja Tetranychus urticae (Kochj (Acari: Tetranychidae).Nota: resultados parciales obtenidos en esta tesis fueron publicados como: Estudio de la entomofauna asociada al cultivo de Amaranthus en la provincia de La Pampa, Argentina. Niveyro, S., C.A. Saenz, L.O. Falkenstein y E.M. Baudino. 30° Congreso Argentino de Horticultura. 1° Simposio Internacional sobre Cultivos Protegidos. 25 al 28 de septiembre de 2007. La Plata. Buenos Aires. Argentina. Pag 378

Aging and Error Processing: Age Related Increase in the Variability of the Error-Negativity Is Not Accompanied by Increase in Response Variability

Background: Several studies report an amplitude reduction of the error negativity (Ne or ERN), an event-related potential occurring after erroneous responses, in older participants. In earlier studies it was shown that the Ne can be explained by a single independent component. In the present study we aimed to investigate whether the Ne reduction usually found in older subjects is due to an altered component structure, i.e., a true alteration in response monitoring in older subjects. Methodology/Principal Findings: Two age groups conducted two tasks with different stimulus response mappings and task difficulty. Both groups received fully balanced speed or accuracy instructions and an individually adapted deadline in both tasks. Event-related potentials, Independent Component analysis of EEG-data and between trial variability of the Ne were combined with analysis of error rates, coefficients of variation of RT-data and ex-Gaussian fittings to reaction times. The Ne was examined by means of ICA and PCA, yielding a prominent independent component on error trials, the Ne-IC. The Ne-IC was smaller in the older than the younger subjects for both speed and accuracy instructions. Also, the Ne-IC contributed to a much lesser extent to the Ne in older than in younger subjects. RT distribution parameters were not related to Ne/ERP-variability. Conclusions/Significance: The results show a genuine reduction as well as a different component structure of the Ne in older compared to young subjects. This reduction is not reflected in behaviour, apart from a general slowing of olde

Inverse Vulcanization of Styrylethyltrimethoxysilane–Coated Surfaces, Particles, and Crosslinked Materials

Sulfur as a side product of natural gas and oil refining is an underused resource. Converting landfilled sulfur waste into materials merges the ecological imperative of resource efficiency with economic considerations. A strategy to convert sulfur into polymeric materials is the inverse vulcanization reaction of sulfur with alkenes. However, the materials formed are of limited applicability, because they need to be cured at high temperatures (>130 °C) for many hours. Herein, we report the reaction of elemental sulfur with styrylethyltrimethoxysilane. Marrying the inverse vulcanization and silane chemistry yielded high sulfur content polysilanes, which could be cured via room temperature polycondensation to obtain coated surfaces, particles, and crosslinked materials. The polycondensation was triggered by hydrolysis of poly(sulfur‐r‐styrylethyltrimethoxysilane) (poly(S$_{n}$‐r‐StyTMS) under mild conditions (HCl, pH 4). For the first time, an inverse vulcanization polymer could be conveniently coated and mildly cured via post‐polycondensation. Silica microparticles coated with the high sulfur content polymer could improve their Hg$^{2+}$ ion remediation capability