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X-ray absorption near edge structure (XANES) and electrical measurements were used to elucidate the local structure and electronic changes of copper(II) oxide (CuO) nanostructures under working conditions. For this purpose, a sample holder layout was developed enabling the simultaneous analysis of the spectroscopic and electrical properties of the sensor material under identical operating conditions. The influence of different carrier gases (e.g., air and N2) on the CuO nanostructures behavior under reducing conditions (H2 gas) was studied to analyze how a particular gas atmosphere can modify the oxidation state of the sensor material in real time.

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The focus of this paper is on the analysis of the structural and electronic order-disorder effects at long, medium and short ranges of titanium dioxide (TiO2) nanoparticles synthesized by the sol-gel process followed by the microwave-assisted solvothermal (MAS) method at low temperatures and short reaction times. X-ray diffraction (XRD), Rietveld refinement, micro-Raman (MR) spectroscopy, transmission electron microscopy (TEM) and X-ray spectroscopy (EDX) were used to characterize the TiO2 nanoparticles. Optical properties were investigated by ultraviolet-visible (UV-vis) and photoluminescence (PL) measurements performed at room temperature. XRD and Rietveld refinement confirmed the presence of the anatase and brookite phases; nonetheless anatase is the major phase. The X-ray photoelectron spectroscopy (XPS) analysis revealed the presence of only Ti(4+) but the nonstoichiometry revealed that TiO2 NPs contain defects assigned to oxygen vacancies that lead to structural and electronic order-disorder effects observed by band gap narrowing and PL wide band emission. These intermediary energy levels (shallow and deep levels) created within the band gap act as acceptors/donors of electrons and recombination centers. The oxygen vacancies (VO(x), VO˙ and VO˙˙) responsible by degree of structural order-disorder are related to distortions (tilts) on the [TiO6] octahedron and changes in the bond lengths and bond angles between oxygen and titanium atoms that gave rise to new species of cluster makers such as [TiO6]', [TiO5·VO(x)], [TiO5·VO˙] and [TiO5·VO˙˙]. This structural transformation is consistent with a redistribution of electron density from highly ordered [TiO6](x) clusters which form distorted [TiO6]' as well as complex [TiO5·VO(x)], [TiO5·VO˙] and [TiO5·VO˙˙] clusters assigned to oxygen vacancies which were understood as displacements in the oxygen atoms' position in the bond lengths (Ti-O).

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The influence of tetrabutylammonium hydroxide on the phase composition (cubic zinc blende versus hexagonal wurtzite) of ZnS nanoparticles was studied. The ZnS nanoparticles were prepared by a microwave-assisted solvothermal method, and the phase structure and optical properties along with the growth process of ZnS nanoparticles were studied. We report XRD, FE-SEM, EDXS, UV-vis and PL measurements, and first-principles calculations based on TDDFT methods in order to investigate the structural and electronic properties and the growth mechanism of ZnS nanostructures. The effects as well as the merits of microwave heating on the process and characteristics of the obtained ZnS nanostructures and their performance are reported.

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A avaliação radiográfica do casco é essencial no diagnóstico e na avaliação da laminite em equinos, contudo poucos estudos têm sido feitos em raças nacionais. O objetivo deste trabalho foi realizar a morfometria de imagens radiográficas obtidas do dígito de éguas Mangalarga Marchador (MM), a fim de obter um perfil de medidas indicadoras de laminite nessa população e comparar grupos sem (escore corporal 5 e 6) e com (escore corporal 7 e 8) sinais de sobrepeso. Não houve diferença significativa entre os valores para as medidas dos dois grupos (P>0,05), mas verificou-se correlação positiva entre a distância entre os planos da linha coronária e do ápice do processo extensor (afundamento da falange distal) e indicadores de deposição de gordura localizada no pescoço e na base da cauda. Os achados demonstram que a morfometria radiográfica do dígito dessa população de equinos Mangalarga Marchador difere da de raças estrangeiras. Além disso, nos animais estudados, éguas com escore corporal 7 e 8 não aparentaram estarem mais sujeitas à laminite, uma vez que não houve diferença entre a morfometria de éguas com escore inferior. Entretanto, as correlações positivas entre índices de obesidade e a distância de afundamento da falange distal indicam que éguas Mangalarga Marchador também estão sujeitas à ocorrência de laminite associada à obesidade...

The radiographic evaluation of the hoof is essential in the diagnosis and follow-up of equine laminitis; however, few studies have been conducted in Brazilian breeds. The aim was to perform the morphometry of radiographic images taken from the digit of Mangalarga Marchador in order to obtain a profile of measurements indicative of laminitis in this population. We also compared measurements form mares without (body score 5 and 6) and with (body score 7 and 8) signs of overweight. There was no significant difference between measurements from the two groups (P> 0.05), but there was significant positive correlation between founder distance and signs of adiposity in the neck and in the base of the tail. Findings from this study demonstrate that radiographic morphology of the hoof from this population of Mangalarga Marchador mares differ from standard international reference values. Furthermore, in this group of mares, those with body condition grading 7 and 8 did not seem to be more prone to develop laminitis, since there was no difference when they were compared with mares showing lower grades. However, a significant correlation among founder distance and signs of adiposity in the neck and base of tail indicate that Mangalarga Marchador mares are also prone to obesity-associated laminitis...

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RESUMO

A avaliação radiográfica do casco é essencial no diagnóstico e na avaliação da laminite em equinos, contudo poucos estudos têm sido feitos em raças nacionais. O objetivo deste trabalho foi realizar a morfometria de imagens radiográficas obtidas do dígito de éguas Mangalarga Marchador (MM), a fim de obter um perfil de medidas indicadoras de laminite nessa população e comparar grupos sem (escore corporal 5 e 6) e com (escore corporal 7 e 8) sinais de sobrepeso. Não houve diferença significativa entre os valores para as medidas dos dois grupos (P>0,05), mas verificou-se correlação positiva entre a distância entre os planos da linha coronária e do ápice do processo extensor (afundamento da falange distal) e indicadores de deposição de gordura localizada no pescoço e na base da cauda. Os achados demonstram que a morfometria radiográfica do dígito dessa população de equinos Mangalarga Marchador difere da de raças estrangeiras. Além disso, nos animais estudados, éguas com escore corporal 7 e 8 não aparentaram estarem mais sujeitas à laminite, uma vez que não houve diferença entre a morfometria de éguas com escore inferior. Entretanto, as correlações positivas entre índices de obesidade e a distância de afundamento da falange distal indicam que éguas Mangalarga Marchador também estão sujeitas à ocorrência de laminite associada à obesidade.(AU)

The radiographic evaluation of the hoof is essential in the diagnosis and follow-up of equine laminitis; however, few studies have been conducted in Brazilian breeds. The aim was to perform the morphometry of radiographic images taken from the digit of Mangalarga Marchador in order to obtain a profile of measurements indicative of laminitis in this population. We also compared measurements form mares without (body score 5 and 6) and with (body score 7 and 8) signs of overweight. There was no significant difference between measurements from the two groups (P> 0.05), but there was significant positive correlation between founder distance and signs of adiposity in the neck and in the base of the tail. Findings from this study demonstrate that radiographic morphology of the hoof from this population of Mangalarga Marchador mares differ from standard international reference values. Furthermore, in this group of mares, those with body condition grading 7 and 8 did not seem to be more prone to develop laminitis, since there was no difference when they were compared with mares showing lower grades. However, a significant correlation among founder distance and signs of adiposity in the neck and base of tail indicate that Mangalarga Marchador mares are also prone to obesity-associated laminitis.(AU)

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In this letter, we report, for the first time, the real-time in situ nucleation and growth of Ag filaments on α-Ag2WO4 crystals driven by an accelerated electron beam from an electronic microscope under high vacuum. We employed several techniques to characterise the material in depth. By using these techniques combined with first-principles modelling based on density functional theory, a mechanism for the Ag filament formation followed by a subsequent growth process from the nano- to micro-scale was proposed. In general, we have shown that an accelerated electron beam from an electronic microscope under high vacuum enables in situ visualisation of Ag filaments with subnanometer resolution and offers great potential for addressing many fundamental issues in materials science, chemistry, physics and other fields of science.

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OBJECTIVES: In this research, an experimental and theoretical study was conducted to design a photodegradation mechanism of the amino acid tryptophan (Trp) in hair fibres. METHODS: For the experimental research, Caucasian hair fibres were exposed to several different solar radiation simulation periods. Then, Trp and its photoproducts (N-formylkynurenine and kynurenine) were assayed by excitation and emission spectroscopic analysis. RESULTS: For the theoretical study, reactions involved in the photodegradation of Trp were evaluated by high-level quantum mechanical calculations in a density functional theory (DFT) framework which indicate a probable Trp degradation mechanism with a minimum expended energy pathway. CONCLUSION: The biochemistry concerning these reactions is essentially important for a biological system where the degradation of Trp occurs.

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Highly aligned CaCu(3)Ti(4)O(12) nanorod arrays were grown on Si/SiO(2)/Ti/Pt substrates by radio-frequency sputtering at a low deposition temperature of 300 °C and room temperature. Structural and morphological studies have shown that the nanostructures have a polycrystalline nature and are oriented perpendicular to the substrate. The high density of grain boundaries in the nanorods is responsible for the nonlinear current behavior observed in these arrays. The current-voltage (I-V) characteristics observed in nanorods were attributed to the resistive memory phenomenon. The electrical resistance of microcapacitors composed of CaCu(3)Ti(4)O(12) nanorods could be reversibly switched between two stable resistance states by varying the applied electric field. In order to explain this switching mechanism, a model based on the increase/decrease of electrical conduction controlled by grain boundary polarization has been proposed.

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Neodymium calcium titanate, (Ca(0.99)Nd(0.01))TiO(3) powders were synthesized by the complex polymerization method and heat treated at different temperatures for 2 h under air atmosphere. The structural evolution of these powders as a function of heat treatment temperature was analyzed by X-ray diffraction (XRD) and micro-Raman (MR) spectroscopy. The optical properties were investigated by Ultraviolet-visible (UV-vis) absorption spectroscopy and Photoluminescence (PL) measurements. XRD patterns, Rietveld refinement and MR spectra indicated that the powders heated treated at 750 degrees C for 2 h present an orthorhombic structure without secondary phases. UV-vis measurements suggested the presence of intermediary energy in disordered (Ca(0.99)Nd(0.01))TiO(3) powders. Broad and narrow bands were observed in the PL spectra of these powders when excited with 350 nm wavelength. The broad bands were associated to the structural defects and/or p-d electronic transitions while, the narrow bands were ascribed to f-f transitions arising from Nd(3+) ions.

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SrWO(4) powders were synthesized by the co-precipitation method and processed in a microwave-hydrothermal (MH) at 140 degrees C for different times. The obtained powders were analyzed by X-ray diffraction (XRD), micro-Raman (MR) spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, field-emission gun scanning electron microscopy (FEG-SEM), ultraviolet-visible (UV-vis) absorption spectroscopy and photoluminescence (PL) measurements. XRD patterns and MR spectra showed that the SrWO(4) powders present a scheelite-type tetragonal structure without the presence of deleterious phases. FT-IR spectra exhibited a high absorption band situated at 831.57 cm(-1), which was ascribed to the WO antisymmetric stretching vibrations into the [WO(4)] tetrahedron groups. FEG-SEM micrographs suggested that the processing time is able to influence in the growth process and morphology of SrWO(4) powders. UV-vis absorption spectra revealed different optical band gap values for these powders. A green PL emission at room temperature was verified in SrWO(4) powders when excited with 488 nm wavelength.

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Intense and broad visible photoluminescent (PL) band was observed at room temperature in disordered Pb(Zr0.53Ti0.47)O3 powders. Structural order-disorder was evaluated by different methods. XANES results pointed to the presence of different coordination modes of disordered Ti powders, and in the ordered sample the local structure around titanium atoms is characteristic of the structurally ordered PZT with only TiO6 units. Only samples containing simultaneous structural order and disorder in their network present the intense visible PL emission at room temperature.

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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.

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The emission of wide band photoluminescence showed a synergic effect on barium zirconate and barium titanate thin films in alternate multilayer system at room temperature by 488 nm exiting wavelength. The thin films obtained by spin-coating were annealed at 350, 450, and 550 degrees C for 2 h. The X-ray patterns revealed the complete separation among the BaTiO3 and BaZrO3 phases in the adjacent films. Visible and intense photoluminescence was governed by BaZrO3 thin films in the multilayer system. Quantum mechanics calculations were used in order to simulate ordered and disordered thin films structures. The disordered models, which were built by using the displacement of formers and modifier networks, showed a different symmetry in each system, which is in accordance with experimental photoluminescence emission, thus allowing to establish a correlation among the structural and optical properties of these multilayered systems.

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In this work it is presented for the first time the nanostructured hydroxyapatites doped with 0.5, 1.0 and 2.0 wt% of Eu(3+) prepared at room temperature by the mechanical alloying technique. X-ray diffraction powder (XRD), infrared (IR) and Raman scattering spectroscopy, scanning electron microscopy (SEM), microhardness measurements as well as luminescent data of Eu(3+) were used to investigate the structural and optical properties of these nanomaterials. The electrical and dielectrical analyses were used with the intention of having a better comprehension about the electromagnetic fields in pure and doped hydroxyapatites.

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RATIONALE: Identification of asthmatic subjects with low perception of dyspnea (POD) that are at higher risk of hospitalization, near-fatal and fatal asthma could improve their management. OBJECTIVE: Create a simple procedure that facilitate the recognition of low POD. METHODS: We enrolled near fatal asthma (NFA) subjects and a wide spectrum of non-NFA subjects. Each subject was asked to stop breathing at end-expiration. Dyspnea was assesssed by a modified Borg scale. To design the new index, we combined the Borg score at the end of the voluntary breath-holding maneuver with the airway limitation. The equation was as follows: FEV(1)/FVC%/(breath-holding time in seconds/final Borg score minus basal Borg score). RESULTS: Eleven NFA subjects (4 females) aged 21-73yr and 55 non-NFA (14 severe, 18 moderate and 23 mild asthmatic subjects) completed the study. The threshold value of the index that could predict POD is <12. The mean (+/-sd) of the new index perception was significantly lower in NFA group (n=11; 5.21+/-3.59; vs. n=55; 13.67+/-11.08; P=0.006). This threshold value had 100% sensitivity and it best discriminated between mild and NFA groups. The negative likelihood ratio (when the index > or = 12) was zero. A result > or = 12 represented an almost null probability of poor POD. CONCLUSION: The breath-holding test is simple and rapid. Its negative likelihood ratio was zero. Accordingly, a test result of 12 or greater might exclude the probability of poor perception of dyspnea in subjects with stable asthma.

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A new method for high-resolution analyses of hair surface charge density under ambient conditions is presented in this paper. Electrostatic force microscopy (EFM) is used here to analyze changes in surface charge density in virgin hair, bleached hair, and hair treated with a cationic polymer. The atomic force microscopy technique is used concomitantly to analyze morphological changes in hair roughness and thickness. The EFM images depict exactly how the polymer is distributed on the surface of the hair fiber. The EFM's powerful analytical tools enabled us to evaluate the varying degrees of interaction between the hair fiber surface charge density and the cationic polymer. The surface charge density and the polymer's distribution in the hair fibers are presented in the light of EFM measurements.

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This communication describes, for the first time, the growth of SnO2 nanoribbons by a controlled carbothermal reduction process. An analysis of the transmission electron microscopy image revealed that these nanoribbons have a well-defined shape, with a typical width in the range of 70-300 nm. In general, the nanostructured ribbons were more than 100 microns in length. The results reported here support the hypothesis that this ribbon-like nanostructured material grows by a vapor-solid process. This study introduces two hypotheses to explain the SnO2 nanoribbon growth process.

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Entre los meses de abril y noviembre de 1991 se realizaron en el Hospital de La Samaritana, 164 herniorrafias inguinales, de las cuales 50 ( 30 por ciento ) se practicaron bajo anestesia local. Este ultimo procedimiento resulto ser fácilmente aplicable en nuestro medio, bien aceptado por el paciente y el medico tratante y con costos menores que los de la anestesia general o regional. No se presentaron complicaciones transoperatorias. Ocho pacientes ( 12 por ciento ) presentaron hematoma posoperatorio, ninguno de los cuales requirio reintervencion y 1 paciente ( 2 por ciento ) presento infeccion de la herida quirurgica que requirio tratamiento con antibioticos con herida abierta.

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A micromethod for passive Hemagglutination is described for the detection of IBR antibodies in serum samples of nine herds. The samples correspond to different zones of the province Buenos Aires. In animals without clinical signs the proportion of positives was 43.60%; in herds with signs consistent with the disease, this value attained 66.4% positivity (Tables 1 and 2). The feasibility of this method is discussed. Some variants introduced into the original technique are described.

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