947 resultados para COMPOUND-I FORMATION


Relevância:

30.00% 30.00%

Publicador:

Resumo:

Pós-graduação em Geografia - IGCE

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Pós-graduação em Química - IQ

Relevância:

30.00% 30.00%

Publicador:

Resumo:

The organic charge-transfer salt EtMe3P[Pd(dmit)(2)](2) is a quasi-two-dimensional Mott insulator with localized spins S = 1/2 residing on a distorted triangular lattice. Here we report measurements of the uniaxial thermal expansion coefficients alpha(i) along the in-plane i = a and c axis as well as along the out-of-plane b axis for temperatures 1.4 K <= T <= 200 K. Particular attention is paid to the lattice effects around the phase transition at T-VBS = 25 K into a low-temperature valence-bond-solid phase and the paramagnetic regime above where effects of short-range antiferromagnetic correlations can be expected. The salient results of our study include (i) the observation of strongly anisotropic lattice distortions accompanying the formation of the valence-bond-solid phase, and (ii) a distinct anomaly in the thermal expansion coefficients in the paramagnetic regime around 40 K. Our results demonstrate that upon cooling through T-VBS the in-plane c axis, along which the valence bonds form, contracts while the second in-plane a axis elongates by the same relative amount. Surprisingly, the dominant effect is observed for the out-of-plane b axis which shrinks significantly upon cooling through T-VBS. The pronounced anomaly in alpha(i) around 40 K is attributed to short-range magnetic correlations. It is argued that the position of this maximum, relative to that in the magnetic susceptibility around 70 K, speaks in favor of a more anisotropic triangular-lattice scenario for this compound than previously thought.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

The processing of ferroelectric BaBi4Ti4O15 (BBT) ceramics from powders prepared by conventional solid state reaction (SSR) and mechanochemical activation (MA) has been investigated. It was shown that MA synthesis reduces the synthesis temperature of BBT powders, leading to smaller particles with reduced anisotropy and consequently to smaller grain size of ceramics. Dielectric properties were investigated in a wide range of temperatures (20-800 degrees C) and frequencies (1.21 kHz to 1 MHz). The relative dielectric permittivity at Curie temperature was higher for solid state obtained ceramics than for the mechanically treated ones. The conductivity of sintered samples was studied, suggesting decreasing of conductivity of BBT-MA in comparison with BBT-SS ceramics. The influence of the grain and the grain boundaries contribution to the dielectric behavior in both ceramics was analyzed through impedance spectroscopy. A well-defined ferroelectric hysteresis loop was obtained for both samples. (C) 2014 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

trans,trans-2,4-Decadienal (DDE) is an important breakdown product of lipid peroxidation. This aldehyde is cytotoxic to mammalian cells and is known to be implicated in DNA damage. Therefore, attempts were made in this work to assess the reactivity of DDE with 2'-deoxyadenosine (dAdo). It was shown that DDE is able to bind to 2'-deoxyadenosine, yielding highly fluorescent products. Besides 1,N-6-etheno-2'-deoxyadenosine (epsilon dAdo), two other related adducts, 1-[3-(2-deoxy-beta-D-erythro-pentofuranosyl)3H-imidazo[2,1-i]purin-7-yl]-1,2,3-octanetriol and 1-[3-(2-deoxy-beta-D-erythro-pentofuranosyl)-3H-imidazo[2,1-i]purin-7-yl]-1,2-heptanediol, were isolated by reverse phase high-performance liquid chromatography and characterized on the basis of their UV, fluorescence, nuclear magnetic resonance, and mass spectrometry features. The reaction mechanism for the formation of the DDE-2'-deoxyadenosine adducts involves 2,4-decadienal epoxidation and subsequent addition to the N-2 amino group of 2'-deoxyadenosine, followed by cyclization at the N-1 site. Adducts differ by the length of carbon side chain and the number of hydroxyl groups. The present data indicate that DDE can be epoxidized by peroxides, and the resulting products are able to form several adducts with 2'-deoxyadenosine and/or DNA. Endogenous DNA adduct formation can contribute to the already reported high cytotoxicity of DDE to mammalian cells.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

This study presents the results from a qualitative resource, based on research-action methodology, which examined the innovate teaching practices implementations in the Calculus I during 2011 year. The analysis of collected data from three used sources – an initial questionnaire, an exploratory-investigative classroom, and an interview with some students at the end of the second semester – reveals that the students had appropriated of the technological recourses, using it as a tool to look for the knowledge. The investigative activities with the use of information technologies made the use of multiple representations in solving mathematical tasks, making the transition of numerical, algebraic and geometrical results possible for the students when they have looking for validation of their hypotheses and conjectures during mathematical problems solving. This works helped in the insertion of new practices in the discipline, and their results validate the proposal presented by the teacher, which is the discipline of Calculus use, whose character is strongly linked to the training content of the student, as a discipline whose can contributed to the pedagogical formation of the graduation student, leading him to know the Mathematical Education possibilities, specially the Mathematical Investigation - Solving Problems, in the outlook of dialogued classes where the teacher assumes the facilitator role and where the students become actives in their pursuit of knowledge

Relevância:

30.00% 30.00%

Publicador:

Resumo:

This article aims to describe how ICT can contribute to the training of teachers on sex education through the lived experience with the implementation of Workshops, which occurred on I COES - I Conference online of sexual education. This Conference was organized by the University of Lisbon-PT, in partnership with UNESP, SP and SC-UDESC. I COES involved education professionals, who work directly in the school to discuss and exchange their experiences related to sexuality education and related fields, through an online space. The research on teacher formation, initial and continuing on sexuality, sex education, gender and sexual diversity, have demonstrated the need to promote and encourage teachers from all areas, to adopt an intentional and emancipatory, their role as sexual educators . Through web conferencing tool Cisco System, I COES was enable the interaction and questioning of ninety five teachers from various parts of Brazil and Portugal, providing opportunities for rich moments of dialogue and reflection on the issues already mentioned, referring to the brazilian and portuguese realities.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Aim The aim of the present study was to evaluate the effect of surface roughness (roughness average [Ra] μm) on the hydrophobicity of a denture-base acrylic resin and the initial adherence and biofilm formation of Candida albicans (C. albicans). Methods Disk-shaped specimens were divided into six groups: Ra 0.05, Ra 0.2, Ra 0.4, Ra 0.8, Ra 1.5, and Ra 3.0. Water contact angles (WCA) were measured, and the specimens incubated with C. albicans for 90 min (initial adherence, n = 108) or 48 h (biofilm formation, n = 108). Adhered and biofilm cells were evaluated by c.f.u./mL and 2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide (XTT), and the correlation between the two methods was evaluated. The surface of the specimens and cells (adhered and biofilm) were also analyzed by scanning electron microscopy (SEM). Results Groups Ra 0.05 and 3.0 exhibited the lowest (~75°) and the highest (~100°) WCA mean values, respectively. For both initial adherence and biofilm formation, no statistically-significant differences were observed among all groups, as determined by c.f.u./mL and XTT. A positive correlation between these two methods was found. SEM analysis showed the presence of scratches and valleys on the acrylic specimens and densely-packed yeast cells covering the entire surface. Conclusions Roughness significantly increased hydrophobicity (WCA), but had no effect on the number and metabolic activity of adherent and biofilm cells of C. albicans.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

This work focused on research a course of continuing education for teachers of Physical Education, offered in a city of São Paulo in 2013. Adopting as a benchmark analysis of models of continuing education in teaching, investigative question that guided this study was: what are the implications of this formative process in the formation and performance of the participating teachers?. With this guiding question, four were the objectives we seek to respond to this analysis: first identify the profile of teachers as well as the participation and involvement of the same course developed; 2 map and analyze the manifestations of teachers throughout the course; 3 reflect on the role of teachers in relation to approaches and/or distances with the common physical education curriculum proposed by the municipality; 4 identify and analyze the reflections on the course conducted. The methodological approach was qualitative and eighteen participants were teachers of a school system in a city of São Paulo, active in cycle I (1 to 5 years) of primary school. Data collection was carried out in two phases, with the participants in the first stage seventeen teachers and three teachers in the second stage that in addition to acting in the cycle I also actively participated in the course. Data were obtained in phase one using a diagnostic interview recorded on voice recorder and transcripts of observations and recorded in video and voice recorder from sixteen meetings of the continuing education course conducted in 2013 and phase two included the observation of classes teachers in the 2nd half of 2013, ending with a final interview. Demonstrations of physical education teachers in the course, as well as the situations observed and interviews indicated that on the profile of teachers are in the age range 30-58 years to serve at least five years in schools and most (10) does not work elsewhere. Another observation is that most of the participating teachers when thes...

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Pós-graduação em Agronomia (Energia na Agricultura) - FCA

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)