Stabilization of tetragonal/cubic phase in Fe doped Zirconia grown by atomic layer deposition

Achieving high temperature ferromagnetism by doping transition metals thin films is seen as a viable approach to integrate spin-based elements in innovative spintronic devices. In this work we investigated the effect of Fe doping on structural properties of ZrO2 grown by atomic layer deposition (ALD) using Zr(TMHD)4 for Zr and Fe(TMHD)3 for Fe precursors and ozone as oxygen source. The temperature during the growth process was fixed at 350{\deg}C. The ALD process was tuned to obtain Fe doped ZrO2 films with uniform chemical composition, as seen by time of flight secondary ion mass spectrometry. The control of Fe content was effectively reached, by controlling the ALD precursor pulse ratio, as checked by X-ray photoemission spectroscopy (XPS) and spectroscopic ellipsometry. From XPS, Fe was found in Fe3+ chemical state, which maximizes the magnetization per atom. We also found, by grazing incidence X-ray diffraction, that the inclusion of Fe impurities in ZrO2 induces amorphization in thin ZrO2 films, while stabilizes the high temperature crystalline tetragonal/cubic phase after rapid thermal annealing at 600{\deg}C.Comment: 11 pages, 7 figures, 1 Tabl

Viabilidade econômica agrícola e responsabilidade ambiental em unidades rurais de produção orgânica e convencional em Mundo Novo, MS.

bitstream/item/69064/1/099-recalde-viabilidade.pdfPublicado também no Cadernos de Agroecologia, v. 7, n.2, 2012

Anomalous Aharonov--Bohm gap oscillations in carbon nanotubes

The gap oscillations caused by a magnetic flux penetrating a carbon nanotube represent one of the most spectacular observation of the Aharonov-Bohm effect at the nano--scale. Our understanding of this effect is, however, based on the assumption that the electrons are strictly confined on the tube surface, on trajectories that are not modified by curvature effects. Using an ab-initio approach based on Density Functional Theory we show that this assumption fails at the nano-scale inducing important corrections to the physics of the Aharonov-Bohm effect. Curvature effects and electronic density spilled out of the nanotube surface are shown to break the periodicity of the gap oscillations. We predict the key phenomenological features of this anomalous Aharonov-Bohm effect in semi-conductive and metallic tubes and the existence of a large metallic phase in the low flux regime of Multi-walled nanotubes, also suggesting possible experiments to validate our results.Comment: 7 figure

Sistemas agroflorestais biodiversos: estilo ecológico de agricultura em assentamentos ruraisemáreas de transição ecológica de Mata Atlântica e Cerrado do Estado de Mato Grosso do Sul.

Estilos ecológicos de agricultura abrangemdiferentes práticas nas propriedades rurais, as quaisintegram atividades produtivas com a conservação da natureza. Neste contexto, esse trabalhoobjetivaanalisar sistemas agroflorestais biodiversos (SAF?s) como estilosecológicosde agricultura, a partir dedeterminadascaracterísticas que promovem a conservação da biodiversidade e a segurança alimentar e nutricional dos agricultores.Para tanto, realizou-se um estudo exploratório e descritivo utilizando-se de levantamento bibliográfico e pesquisa de campo realizada em vinte e duas propriedades situadas emassentamentos rurais localizadosno estado de Mato Grosso do Sul.Aspeculiaridadespresentes nas características dos sistemas implantados nas propriedades contribuem para fortalecer a proposição desseestilo de agriculturaecológicaque depende de relações sociais, de trocas de experiências e orientações entre os agricultores e atores envolvidos (assistência técnica, ensino, pesquisa). Os seus múltiplos benefícios (ambientais, econômicos, segurança alimentar, sociais e culturais)se conformam num estilo ecológico de agricultura, que promove a sustentabilidade para os assentamentos de reforma agrária onde esses agroecossistemasestão implantados

Circulating MicroRNA-15a Associates With Retinal Damage in Patients With Early Stage Type 2 Diabetes

: Circulating microRNAs are potential biomarkers of type 2 diabetes mellitus (T2DM) and related complications. Here, we investigated the association of microRNA-15a with early retinal damage in T2DM. A cohort of untreated subjects screened for intermediate/high risk of T2DM, according to a score assessment questionnaire, and then recognized to have a normal (NGT) or impaired (IGT) glucose tolerance or T2DM was studied. The thickness of the ganglion cell complex (GCC), an early marker of retinal degeneration anteceding overt retinopathy was assessed by Optical Coherence Tomography. Total and extracellular vesicles (EV)-associated microRNA-15a quantity was measured in plasma by real time PCR. MicroRNA-15a level was significantly higher in subjects with IGT and T2DM compared with NGT. MicroRNA-15a abundance was correlated to body mass index and classical diabetes biomarkers, including fasting glucose, HbA1c, insulinemia, and HOMA-IR. Moreover, GCC thickness was significantly reduced in IGT and T2DM subjects compared with NGT controls. Importantly, total microRNA-15a correlated with GCC in IGT subjects, while in T2DM subjects, EV-microRNA-15a negatively correlated with GCC, suggesting that microRNA-15a may monitor initial retinal damage. The assessment of plasma microRNA-15a may help refining risk assessment and secondary prevention in patients with preclinical T2DM

The Energetics of Li Off-Centering in K1−x_{1-x}Lix_xTaO3_3; First Principles Calculations

K$_{1-x}$Li$_{x}$TaO$_3$ (KLT) solid solutions exhibit a variety of interesting physical phenomena related to large displacements of Li-ions from ideal perovskite A-site positions. First-principles calculations for KLT supercells were used to investigate these phenomena. Lattice dynamics calculations for KLT exhibit a Li off-centering instability. The energetics of Li-displacements for isolated Li-ions and for Li-Li pairs up to 4th neighbors were calculated. Interactions between nearest neighbor Li-ions, in a Li-Li pair, strongly favor ferroelectric alignment along the pair axis. Such Li-Li pairs can be considered "seeds" for polar nanoclusters in KLT. Electrostriction, local oxygen relaxation, coupling to the KT soft-mode, and interactions with neighboring Li-ions all enhance the polarization from Li off-centering. Calculated hopping barriers for isolated Li-ions and for nearest neighbor Li-Li pairs are in good agreement with Arrhenius fits to experimental dielectric data.Comment: 14 pages including 10 figures. To Physical Review B. Replaced after corrections due to referees' remark

Ispitivanje kompatibilnosti nateglinida s pomoćnim tvarima u razvoju tableta nateglinida za trenutno oslobađanje

Experiments were done to assess the compatibility of nateglinide with selected excipients in the development of immediate release tablets of nateglinide by thermal and isothermal stress testing (IST) techniques. To evaluate the drug-excipient compatibility, different techniques such as differential scanning calorimetric (DSC) study, infra-red (IR) spectrophotometric study and isothermal stress testing were adopted. The results of DSC study showed that magnesium stearate exhibited some interaction with nateglinide. However, the results of IR, and IST studies showed that all the excipients used in the formula were compatible with nateglinide. Optimized formulations developed using the compatible excipients were found to be stable over 3 months of accelerated stability studies (40 ± 2 C and 75 ± 5 % RH). Overall, compatibility of excipients with nateglinide was successfully evaluated using a combination of thermal and IST methods and the formulations developed using the compatible excipients were found to be stable.Koristeći termičke metode kao što su diferencijalna pretražna kalorimetrija (DSC) i infra-crvena spektrofotometrija (IR), te izotermička stres-testiranja (IST) ispitana je kompatibilnost nateglinida s izabranim ekscipiensima u razvoju tableta nateglinida za trenutno oslobađanje. Rezultati DSC ispitivanja pokazala su da magnezijev stearat stupa u određenu interakciju s nateglinidom. Međutim, IR i IST ispitivanja pokazuju da su svi upotrijebljeni ekscipiensi kompatibilni s nateglinidom. Optimirana formulacija bila je stabilna preko 3 mjeseca u testovima ubrzanog starenja (40 ± 2 C i 75 ± 5 % RH). Kompatibilnost ekscipiensa s nateglinidom uspješno je evaluirana koristeći kombinaciju termičke i IST metode, a formulacije razvijene koristeći kompatibilne ekscipiense bile su stabilne