Chemical deposition of La0.7Ca0.3MnO3±δ films on ceramic substrates

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Structural, electronic structure and magnetic studies of SmFe1-xNixO3 (x <= 0.5)

We present the structural, electronic structure and magnetic studies of Ni doped SmFeO3. The X-ray diffraction (XRD) studies confirm the single phase nature of the samples having orthorhombic Pbnm structure and the unit-cell volume is decreasing with the increase of Ni concentration. X-ray absorption spectroscopy (XAS) studies on O K. Fe L-3.2, Ni L-3.2 and Sm M-5.4 edges of SmFe1-xNixO3 (x <= 0.5) samples along with the reference compounds revealed the homo-valence state of Fe and Ni in these materials. From magnetization studies it has been observed the materials exhibit ferromagnetic and anti-ferromagnetic sub-lattices, which are strongly dependent on the thermo-magnetic state of the system. (C) 2010 Elsevier B.V. All rights reserved.

The optical absorption edge of nanocrystalline Ga(1-x)Mn(x)N films deposited by reactive sputtering

We have focused on the optical absorption edge of nanocrystalline Ga(1-x)Mn(x)N (0.00 <= x <= 0.18) films deposited by reactive RF magnetron sputtering. The films obtained are nanocrystalline with grain sizes of about 25 nm, having wurtzite structure and strong orientation texture in the c-axis direction. The optical characterizations of the absorption edges were obtained in the 190-2600 nm spectral range. The increase of the Mn content causes an increase of the absorption coefficient which can be clearly noticed at low energies, and a quasi-linear decrease of the optical gap. Broad absorption bands observed around similar to 1.3 and similar to 2.2 eV were associated with transitions between the Mn acceptor level and the valence and conduction bands, respectively. The observed changes in the optical properties due to the Mn incorporation observed in these nanocrystalline films are similar to those reported for ferromagnetic GaMnN single-crystal films.

Magnetic interactions and spin-reversal mechanism in ErMn1-xCoxO3-delta samples

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Toward an understanding of intermediate- and short-range defects in ZnO single crystals. A combined experimental and theoretical study

A joint use of experimental and theoretical techniques allows us to understand the key role of intermediate- and short-range defects in the structural and electronic properties of ZnO single crystals obtained by means of both conventional hydrothermal and microwave-hydrothermal synthesis methods. X-ray diffraction, Raman spectra, photoluminescence, scanning electronic and transmission electron microscopies were used to characterize the thermal properties, crystalline and optical features of the obtained nano and microwires ZnO structures. In addition, these properties were further investigated by means of two periodic models, crystalline and disordered ZnO wurtzite structure, and first principles calculations based on density functional theory at the B3LYP level. The theoretical results indicate that the key factor controlling the electronic behavior can be associated with a symmetry breaking process, creating localized electronic levels above the valence band.

Experimental and theoretical studies on the enhanced photoluminescence activity of zinc sulfide with a capping agent

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Efeito do alerta e valência emocional nos componentes de lembrança e familiaridade da memória episódica

The episodic memory system allows us to retrieve information about events, including its contextual aspects. It has been suggested that episodic memory is composed by two independent components: recollection and familiarity. Recollection is related to the vivid e detailed retrieval of item and contextual information, while familiarity is the capability to recognize items previously seen as familiars. Despite the fact that emotion is one of the most influent process on memory, only a few studies have investigated its effect on recollection and familiarity. Another limitation of studies about the effect of emotion on memory is that the majority of them have not adequately considered the differential effects of arousal and positive/negative valence. The main purpose of the current work is to investigate the independent effect of emotional valence and arousal on recollection and familiarity, as well as to test some hypothesis that have been suggested about the effect of emotion on episodic memory. The participants of the research performed a recognition task for three lists of emotional pictures: high arousal negative, high arousal positive and low arousal positive. At the test session, participants also rated the confidence level of their responses. The confidence ratings were used to plot ROC curves and estimate the contributions of recollection and familiarity of recognition performance. As the main results, we found that negative valence enhanced the component of recollection without any effect on familiarity or recognition accuracy. Arousal did not affect recognition performance or their components, but high arousal was associated with a higher proportion of false memories. This work highlight the importance of to consider both the emotional dimensions and episodic memory components in the study of emotion effect on episodic memory, since they interact in complex and independent way

Motivação para o trabalho: um estudo com os profissionais de saúde das unidades básicas de saúde do município de Natal RN

This thesis studied the motivation to work among health professionals of the Basic Unities (BUH) in the health network of the city of Natal (RN). It was understood that the work motivation is a process. Then, the expectation theory was applied and motivation components (results of work, expectative, valence, instrumentality, and motivational force) were used to analyses. It s understanding the motivation as multifaceted phenomenon, the psycho sociological perspective was adopted. The research was developed in two phases: one with application of Work Motivation and Meaning Inventory (WMMI), and another with interview. In the first phases, the analysis of results revealed that the major factors contributing to increase the motivational force to health professionals in the BUH´s are: in valence, Self Expression and Personal Realization (VF2), Personal and Family Survival (VF3); in expectative, Self Expression and Work Justice (EF1), Safety and Dignity (EF2) and Responsibility (EF4); in instrumentality, Involvement (IF1) and Recognition and Economic Independence (IF4). In opposition, the factors that more contribute to reduce the motivational force are Wear and Dehumanization factors in valence (VF4), in expectative (EF3), and in instrumentality (IF4), behind the Work Justice Factor (IF2). Basing in content analysis of interviews, it was possible to associate by equivalence, the senses presented by health professionals with obtained results of first phase, indicating that the results of second phase corroborated and complemented those of first one. This possibility broadened the comprehension of the studied phenomenon. In speaking of the respondents, it was visible the presence of contents showing that they perceive the Health System and BUH´s in degradation. In the first phase, the participants´ instruction also predict the results in motivation, and in the interviews can be saw that the instruction is associated with the opportunities in outside of system. As work motivation is a process, the impact of personal and occupational characteristics tend to interact with contextual aspects. It was concluded the majority of health professionals present the moderated motivational force, but it was falling because they experience and perceive a degrading context with work condition increasingly unfavorable.

Analysis of natural cis- and trans-polyisoprene mixtures by near-infrared spectrophotometry

Natural trans- and cis-polyisoprenes and mixtures of these polymers were analysed by near-infrared spectrophotometry. The relative absorptivity data versus the amount of isomers in synthetic mixtures showed a non-linear behaviour. The results are compared with literature data from polyisoprenes extracted from other vegetal species. (C) 2000 Elsevier B.V. Ltd. All rights reserved.

Índice de aromaticidade baseado na deslocalização, degenerescência e densidade (D3BIA) para acenos e moléculas homoaromáticas

The aromaticity index is an important tool for the investigation of aromatic molecules. This work consists on new applications of the aromaticity index developed by teacher Caio Lima Firme, so-called D3BIA (density, delocalization, degeneracy-based index of aromaticity). It was investigated its correlation with other well-known aromaticity indexes, such as HOMA (harmonic oscillator model of aromaticity), NICS (nucleus independent chemical shielding), PDI (para-delocalization index), magnetic susceptibility (), and energetic factor in the study of aromaticity of acenes and homoaromatic species based on bisnoradamantanyl cage. The density functional theory (DFT) was used for optimization calculations and for obtaining energetic factors associated with aromaticity and indexes HOMA and NICS. From quantum theory of atoms in molecules (QTAIM) it was obtained the indexes D3BIA, PDI and . For acenes, when the over-mentioned indexes were applied it was observed no correlation except for D3BIA and HOMA (R2=0.752). For bisnoradamantenyl dication and its derivatives, it was obtained a good correlation between D3BIA and NICS. Moreover, it was evaluated solely one of the factors used on D3BIA calculation, the delocalization index uniformity (DIU), so as to investigate its possible influence on stability of chemical species. Then, the DIU was compared with the formation Gibbs free energy of some pairs of carbocations, isomers or not, which each pair had small difference in point group symmetry and no difference among other well-known stability factors. The obtained results indicate that DIU is a new stability factor related to carbocations, that is, the more uniform the electron density delocalization, the more stable the is carbocation. The results of this work validate D3BIA and show its importance on the concept of aromaticity, indicating that it can be understood from degeneracy of atoms belonging the aromatic site, the electronic density in the aromatic site and the degree of uniformity of electron delocalization

Síntese, caracterização e estudo fotofísico de complexos de 4,4- diaminoestilbeno-2,2-dissulfonato com íons lantanídeos

This is a work involving fundamental studies of chemistry where the synthesis and structural characterization, as well as a possible future application of these new compounds as luminescent sensors or sunscreen agents, complexes with 4,4 diaminostilbene-2,2-disulfonic (DSD) and trivalent lanthanide ions La3+, Nd3+, Eu3+, Gd3+ and Yb3+, were synthesized in the ratio of 3 mmol: 1 mmol (DSD: lanthanides). The complexes obtained with these ions were present in powder form and were characterized by complexometric titration with EDTA CHN Elemental analysis, molecular absorption spectroscopy in the ultraviolet region, the absorption spectroscopy in the infrared, thermal analysis (TG / DTG), Nuclear Magnetic Resonance - NMR 1H and Luminescence Spectroscopy. The complexometric titration and CHN analysis, confirmed the TG / DTG which suggest that these complexes have the following general chemical formulas: [La2(C14H12S2O6N2)2(H2O)2Cl2].7H2O,[Nd2(C14H12S2O6N2)2(H2O)2Cl2].6H2O,[Eu2(C14 H12S2O6N2)2(H2O)2Cl2].7H2O,[Gd2(C14H12S2O6N2)2(H2O)2Cl2].4H2O e [Yb2(C14H12S2O6N2)2(H2O)2].6H2O. The disappearance of the bands in the infrared spectrum at 2921 cm-1 and 2623 cm-1 and the displacement of the bands in the spectra of the amine complex indicate that the lanthanide ion is coordinated to the oxygen atoms and the sulfonate groups of the nitrogens amines, suggesting the formation of the dimer. The disappearance of the signal and the displacement signal SO3H amines in the 1H NMR spectrum of this complex are also indicative coordination and dimer formation. The Thermogravimetry indicates that the DSD is thermally stable in the range of 40º to 385°C and their complexes with lanthanide ions exhibit weight loss between 4 and 5 stages. The Uv-visible spectra indicated that the DSD and complexes exhibit cis isomers. The analysis of luminescence indicates that the complexes do not exhibit emission in the region of the lanthanides but an intense emission part of the binder. This is related to the triplet states of the ligand, which are in the lowest energy state emitting lanthanide ions, and also the formation of the dimer that suppress the luminescence of ion Eu3+. The formation of dimer was also confirmed by calculating the europium complex structure using the model Hamiltonian PM6 and Sparkle

Hidrocarbonetos policíclicos aromáticos no meio ambiente: diferenciação de fontes em sedimentos e metabólitos em bile de peixes

Many studies on environmental ecosystems quality related to polycyclic aromatic hydrocarbons (PAH) have been carried out routinely due to their ubiquotus presence worldwide and to their potential toxicity after its biotransformation. PAH may be introduced into the environmet by natural and anthropogenic processes from direct runoff and discharges and indirect atmospheric deposition. Sources of naturally occurring PAHs include natural fires, natural oil seepage and recent biological or diagenetic processes. Anthropogenic sources of PAHs, acute or chronic, are combustion of organic matter (petroleum, coal, wood), waste and releases/spills of petroleum and derivatives (river runoff, sewage outfalls, maritime transport, pipelines). Besides the co-existence of multiples sources of PAH in the environmental samples, these compounds are subject to many processes that lead to geochemical fates (physical-chemical transformation, biodegradation and photo-oxidation), which leads to an alteration of their composition. All these facts make the identification of the hydrocarbons sources, if petrogenic, pyrolytic or natural, a challenge. One of the objectives of this study is to establish tools to identify the origin of hydrocarbons in environmental samples. PAH diagnostic ratios and PAH principal component analysis were tested on a critical area: Guanabara Bay sediments. Guanabara Bay is located in a complex urban area of Rio de Janeiro with a high anthropogenic influence, being an endpoint of chronic pollution from the Greater Rio and it was the scenario of an acute event of oil release in January 2000. It were quantified 38 compounds, parental and alkylated PAH, in 21 sediment samples collected in two surveys: 2000 and 2003. The PAH levels varied from 400 to 58439 ng g-1. Both tested techniques for origin identification of hydrocarbons have shown their applicability, being able to discriminate the PAH sources for the majority of the samples analysed. The bay sediments were separated into two big clusters: sediments with a clear pattern of petrogenic introduction of hydrocarbons (from intertidal area) and sediments with combustion characteristics (from subtidal region). Only a minority of the samples could not display a clear contribution of petrogenic or pyrolytic input. The diagnostic ratios that have exhibited high ability to distinguish combustion- and petroleum-derived PAH inputs for Guanabara Bay sediments were Phenanthrene+Anthracene/(Phenanthrene+Anthracene+C1Phenanthrene); Fluorantene/(Fluorantene+Pyrene); Σ (other 3-6 ring PAHs)/ Σ (5 alkylated PAH series). The PCA results prooved to be a useful tool for PAH source identification in the environment, corroborating the diagnostic indexes. In relation to the temporal evaluation carried out in this study, it was not verified significant changes on the class of predominant source of the samples. This result indicates that the hydrocarbons present in the Guanabara Bay sediments are mainly related to the long-term anthropogenic input and not directly related to acute events such as the oil spill of January 2000. This findings were similar to various international estuarine sites. Finally, this work had a complementary objective of evaluating the level of hydrocarbons exposure of the aquatic organisms of Guanabara Bay. It was a preliminary study in which a quantification of 12 individual biliar metabolites of PAH was performed in four demersal fish representing three different families. The analysed metabolites were 1-hydroxynaphtalene, 2-hidroxinaphtalene, 1hydroxyphenanthrene, 9-hydroxyphenanthrene, 2-hydroxyphenanthrene, 1hydroxypyrene, 3-hidroxibiphenil, 3- hydroxyphenanthrene, 1-hydroxychrysene, 9hydroxyfluorene, 4-hydroxyphenanthrene, 3-hydroxybenz(a)pyrene. The metabolites concentrations were found to be high, ranging from 13 to 177 µg g-1, however they were similar to worldwide regions under high anthropogenic input. Besides the metabolites established by the used protocol, it was possible to verified high concentrations of three other compounds not yet reported in the literature. They were related to pyrolytic PAH contribution to Guanabara Bay aquatic biota: 1-hydroxypyrine and 3-hydroxybenz(a)pyrine isomers

Structural characterization of a new acylpolyaminetoxin from the venom of Brazilian garden spider Nephilengys cruentata

Mario Sergio Palma, Yasuhiro Itagaki, Tsuyoshi Fujita, Hideo Naoki and Terumi Nakajima. Structural characterization of a new acylpolpaminetoxin from the venom of Brazilian garden spider Nephilengys: cruentata. Toxicon 36, 455-493, 1998.-The use of mass spectrometry, in which high-energy CID and charge remote fragmentation both of protonated and sodium-attached molecular ions was applied, afforded the structural elucidation of a new acylgolyaminetoxin with M-W= 801 da from the venom of the Brazilian garden spider Nephilengys cruentata. In spite of having the same M-W of the NPTX-2, previously described in the venom of the Joro spider Nephila clavata, neither toxins are isomers. In order to differentiate them by using the most usual nomenclature, the new toxin was named NPTX-801C and the NPTX-2 was renamed to NPTX-801E. Both toxins have as common structure the 4-hydroxyindole-3-acetyl-asparaginyl-cadaveryl moiety in their molecules and their structure may be represented in a simplified way: NPTX-801E is HO-indole-Asn-Cad-Pta-Orn-Arg and NPTX-801C is HO-indole-Asn-Cad-Gly-Put-Pta-Pta. (C) 1998 Elsevier B.V. Ltd. All rights reserved.

Modifications on PVC films by ultrasound

PVC films submitted to ultrasonic irradiation presented structural changes as probed by infrared measurements. These measurements showed some infrared bands alterations attributed to the increase concentration of some conformational isomers of PVC and the presence of some new species in the macromolecular matrix. (C) 2002 Elsevier B.V. B.V. All rights reserved.

Electromagnetic hadron form factors and higher Fock components

Investigation of the spacelike and timelike electromagnetic form factors of hadrons, within a relativistic microscopical model characterized by a small set of hypothesis, could shed light on the components of hadron states beyond the valence one. Our relativistic approach has been successfully applied first to the pion and then the extension to the nucleon has been undertaken. The pion case is shortly reviewed as an illustrative example for introducing the main ingredients of our approach, and preliminary results for the nucleon in the spacelike range -10 (GeV/c)(2) <= q(2) <= 0 are evaluated.