4,427 research outputs found

    Methyl Ester Functionalized Phenalenyl Arene- and Bipyridine-Ruthenium-Based Complexes for Electroactive Langmuir-Blodgett Films

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    We report the synthesis of a new phenalenyl ligand, functionalized with a methyl ester electron withdrawing group, named 9-hydroxy-1-oxo-1H-phenalen-5-methyl carboxylate (L), and the generated complexes [Ru(bpy)2L]PF6 and [(Ρ6-C6H6)Ru(L)Cl]. Compounds were characterized by spectroscopic and X-ray diffraction methods, and their electrochemical behavior was investigated via cyclic voltammetry and UV-vis spectroelectrochemistry. The one-electron oxidized compounds have an unpaired electron located in the phenalenyl ring, as supported by theoretical calculations (DFT) and EPR results. Langmuir-Blodgett (LB) films deposited by [Ru(bpy)2L]2+/3+ species mixed with stearic acid are electroactive, showing a quasi-reversible wave with E1/2Film1 = 0.74 V and E1/2Film2 = 0.81, which are promising systems that allow access to immobilized open-shell species in the film

    Germinal center architecture disturbance during Plasmodium berghei ANKA infection in CBA mice

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    <p>Abstract</p> <p>Background</p> <p>Immune responses to malaria blood stage infection are in general defective, with the need for long-term exposure to the parasite to achieve immunity, and with the development of immunopathology states such as cerebral malaria in many cases. One of the potential reasons for the difficulty in developing protective immunity is the poor development of memory responses. In this paper, the potential association of cellular reactivity in lymphoid organs (spleen, lymph nodes and Peyer's patches) with immunity and pathology was evaluated during <it>Plasmodium berghei </it>ANKA infection in CBA mice.</p> <p>Methods</p> <p>CBA mice were infected with 1 × 10<sup>6 </sup><it>P. berghei </it>ANKA-parasitized erythrocytes and killed on days 3, 6–8 and 10 of infection. The spleen, lymph nodes and Peyer's patches were collected, fixed in Carson's formalin, cut in 5 μm sections, mounted in glass slides, stained with Lennert's Giemsa and haematoxylin-eosin and analysed with bright-field microscopy.</p> <p>Results</p> <p>Early (day 3) strong activation of T cells in secondary lymphoid organs was observed and, on days 6–8 of infection, there was overwhelming activation of B cells, with loss of conventional germinal center architecture, intense centroblast activation, proliferation and apoptosis but little differentiation to centrocytes. In the spleen, the marginal zone disappeared and the limits between the disorganized germinal center and the red pulp were blurred. Intense plasmacytogenesis was observed in the T cell zone.</p> <p>Conclusion</p> <p>The observed alterations, especially the germinal center architecture disturbance (GCAD) with poor centrocyte differentiation, suggest that B cell responses during <it>P. berghei </it>ANKA infection in mice are defective, with potential impact on B cell memory responses.</p

    Moisture Control, Inoculant and Particle Size in Tropical Grass Silages

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    Decreased fermentation and spoilage losses with improved aerobic stability during feed out can be accomplished by several strategies, such as wilting, addition of microbial additives and moisture absorbents. Particle size reduction may increase bulk density and improve the fermentation. The objective of this trial was to evaluate the effects of particle size, moisture content and a microbial additive on chemical-physical parameters and losses in silages made from Tanzania grass

    \u3cem\u3eTithonia diversifolia\u3c/em\u3e for Ruminant Nutrition

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    India and Brazil lead the world ranking of livestock enteric methane emissions (FAO 2006). According to FAO (2006), Brazil (9.6 Tg of CH4/year) is the highest emitter of methane from cattle, followed by India (8.6 Tg of CH4/year) and the USA (5.1 Tg of CH4/year). In livestock, methane (CH4) formed from enteric fermentation of carbohydrates is primarily responsible for the emissions in the sector. Regarding livestock methane emission, Delgado et al. (2012) evaluated 20 tree and shrub species using in vitro technique and demonstrated a reducing effect on the amount of methane when Tithonia diversifolia was compared with, for example, Cynodon nlemfuensis grass. Tithonia diversifolia belongs to the division - Sphermatophyta; class - Eudicotiledoneae; sub-class - MetaclamĂ­deas; Order - Campanulate; Family - Asteraceae; Genre - Tithonia, and Species - Tithonia diversifolia (Hemsl.), Gray (Souza 2008). Tithonia diversifolia can be very useful in animal nutrition (Fig. 1) by increasing the protein content of animal diet at low cost (Murgueitio et al. 2010) as well as in the recovery of degraded soils for it grows in areas with low levels of fertility and has high ability to absorb phosphorus, even if it is unavailable to other forage species (Kwabiah et al. 2003). The objective of this study was to assess the nutritional qualities, including quantification of enteric methane generated during in vitro ruminal fermentation, of Tithonia diversifolia as an alternative forage for ruminant nutrition in the tropics

    Saddles in the energy landscape probed by supercooled liquids

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    We numerically investigate the supercooled dynamics of two simple model liquids exploiting the partition of the multi-dimension configuration space in basins of attraction of the stationary points (inherent saddles) of the potential energy surface. We find that the inherent saddles order and potential energy are well defined functions of the temperature T. Moreover, decreasing T, the saddle order vanishes at the same temperature (T_MCT) where the inverse diffusivity appears to diverge as a power law. This allows a topological interpretation of T_MCT: it marks the transition from a dynamics between basins of saddles (T>T_MCT) to a dynamics between basins of minima (T<T_MCT).Comment: 4 pages, 3 figures, to be published on PR

    Functional characterization and target discovery of glycoside hydrolases from the digestome of the lower termite Coptotermes gestroi

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    <p>Abstract</p> <p>Background</p> <p>Lignocellulosic materials have been moved towards the forefront of the biofuel industry as a sustainable resource. However, saccharification and the production of bioproducts derived from plant cell wall biomass are complex and lengthy processes. The understanding of termite gut biology and feeding strategies may improve the current state of biomass conversion technology and bioproduct production.</p> <p>Results</p> <p>The study herein shows comprehensive functional characterization of crude body extracts from <it>Coptotermes gestroi </it>along with global proteomic analysis of the termite's digestome, targeting the identification of glycoside hydrolases and accessory proteins responsible for plant biomass conversion. The crude protein extract from <it>C. gestroi </it>was enzymatically efficient over a broad pH range on a series of natural polysaccharides, formed by glucose-, xylose-, mannan- and/or arabinose-containing polymers, linked by various types of glycosidic bonds, as well as ramification types. Our proteomic approach successfully identified a large number of relevant polypeptides in the <it>C. gestroi </it>digestome. A total of 55 different proteins were identified and classified into 29 CAZy families. Based on the total number of peptides identified, the majority of components found in the <it>C. gestroi </it>digestome were cellulose-degrading enzymes. Xylanolytic enzymes, mannan- hydrolytic enzymes, pectinases and starch-degrading and debranching enzymes were also identified. Our strategy enabled validation of liquid chromatography with tandem mass spectrometry recognized proteins, by enzymatic functional assays and by following the degradation products of specific 8-amino-1,3,6-pyrenetrisulfonic acid labeled oligosaccharides through capillary zone electrophoresis.</p> <p>Conclusions</p> <p>Here we describe the first global study on the enzymatic repertoire involved in plant polysaccharide degradation by the lower termite <it>C. gestroi</it>. The biochemical characterization of whole body termite extracts evidenced their ability to cleave all types of glycosidic bonds present in plant polysaccharides. The comprehensive proteomic analysis, revealed a complete collection of hydrolytic enzymes including cellulases (GH1, GH3, GH5, GH7, GH9 and CBM 6), hemicellulases (GH2, GH10, GH11, GH16, GH43 and CBM 27) and pectinases (GH28 and GH29).</p

    Relaxation processes in harmonic glasses?

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    A relaxation process, with the associated phenomenology of sound attenuation and sound velocity dispersion, is found in a simulated harmonic Lennard-Jones glass. We propose to identify this process with the so called microscopic (or instantaneous) relaxation process observed in real glasses and supercooled liquids. A model based on the memory function approach accounts for the observation, and allows to relate to each others: 1) the characteristic time and strength of this process, 2) the low frequency limit of the dynamic structure factor of the glass, and 3) the high frequency sound attenuation coefficient, with its observed quadratic dependence on the momentum transfer.Comment: 11 pages, 3 figure

    A review on the diagnosis and treatment of patients with clinically nonfunctioning pituitary adenoma by the Neuroendocrinology Department of the Brazilian Society of Endocrinology and Metabolism

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    Clinically nonfunctioning pituitary adenomas (NFPA) are the most common pituitary tumors after prolactinomas. The absence of clinical symptoms of hormonal hypersecretion can contribute to the late diagnosis of the disease. Thus, the majority of patients seek medical attention for signs and symptoms resulting from mass effect, such as neuro-ophthalmologic symptoms and hypopituitarism. Other presentations include pituitary apoplexy or an incidental finding on imaging studies. Mass effect and hypopituitarism impose high morbidity and mortality. However, early diagnosis and effective treatment minimizes morbidity and mortality. In this publication, the goal of the Neuroendocrinology Department of the Brazilian Society of Endocrinology and Metabolism is to provide a review of the diagnosis and treatment of patients with NFPA, emphasizing that the treatment should be performed in reference centers. This review is based on data published in the literature and the authors’ experience. Arch Endocrinol Metab. 2016;60(4):374-9

    Elastic constant dishomogeneity and Q2Q^2 dependence of the broadening of the dynamical structure factor in disordered systems

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    We propose an explanation for the quadratic dependence on the momentum QQ, of the broadening of the acoustic excitation peak recently found in the study of the dynamic structure factor of many real and simulated glasses. We ascribe the observed Q2Q^2 law to the spatial fluctuations of the local wavelength of the collective vibrational modes, in turn produced by the dishomegeneity of the inter-particle elastic constants. This explanation is analitically shown to hold for 1-dimensional disordered chains and satisfatorily numerically tested in both 1 and 3 dimensions.Comment: 4 pages, RevTeX, 5 postscript figure

    Digital live-tracking 3-dimensional minisensors for recording head orientation during image acquisition

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    Our objective was to test the value of minisensors for recording unrestrained head position with 6 degrees of freedom during 3-dimensional stereophotogrammetry
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