341 research outputs found

    Piezoelectric resonance in Rochelle salt: the contribution of diagonal strains

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    Within the framework of two-sublattice Mitsui model with taking into account the shear strain ε4\varepsilon_4 and the diagonal strains ε2\varepsilon_2 and ε3\varepsilon_3, a dynamic dielectric response of Rochelle salt X-cuts is considered. Experimentally observed phenomena of crystal clamping by high frequency electric field, piezoelectric resonance and microwave dispersion are described. It is shown that the lowest resonant frequency is always associated with the ε4\varepsilon_4 shear modeComment: 17 pages, 6 figure

    Physical properties of strontium barium niobate thin films prepared by polymeric chemical method

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    Randomly oriented Sr0.75Ba0.25Nb2O6 thin films have been deposited on Pt(111)/Ti/SiO2/Si substrates using a polymeric chemical method to study their physical properties. Refinements of the structure confirm the stoichiometry of the studied films. The relaxor behavior is evidenced by the dielectric measurements and Vögel-Fulcher analysis of the dielectric curves. Lowering the transition temperature (Tm) by about 100 K and asymmetries in the local hysteresis loops well above Tm are discussed in terms of the existence of complex defects in thin films. © 2016 Taylor & Francis Group, LLC

    Nutritional and mineral composition of Opuntia stricta Haw: Balance of macrominerals, renal function and blood metabolites in sheep

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    ABSTRACT This study aimed to evaluate the effect of the inclusion of spineless cactus (Opuntia stricta Haw) in the diet of sheep on the balance of macrominerals, renal function, and blood metabolites. Five sheep cannulated in the rumen (61.5±9.5kg body weight) were used in a 5 × 5 Latin square composed of five diets and five experimental periods. The experimental period lasted 105 days, with five periods of 21 days each. Four diets containing levels of spineless cactus (121, 245, 371, and 500g/kg of dry matter (DM)), and a control diet were evaluated. Samples of the ingredients, orts, feces, urine, and blood were collected. Spineless cactus inclusion in sheep diets increased the DM intake, ash, oxalate, and all macrominerals intake (P 0.05). It is possible to verify that the inclusion of spineless cactus, up to the level of 500g/kg of DM in the sheep diets, does not appear to cause damage to the animal’s health. Its inclusion does not compromise kidney function or blood metabolites evaluated herein

    Photoinduced antibacterial activity of the essential oils from Eugenia brasiliensis lam and Piper mosenii C. DC. by blue led light

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    The objective of this work was to evaluate the phytochemical composition and the antibacterial and antibiotic-modulating activities of the essential oils of Eugenia brasiliensis Lam (OEEb) and Piper mosenii C. DC (OEPm) singly or in association with blue LED (Light-emitting diode) light. The antibacterial and antibiotic-modulatory activities of the essential oils on the activity of aminoglycosides were evaluated to determine the minimum inhibitory concentration (MIC, \u3bcg/mL) in the presence or absence of exposure to blue LED light. The chemical analysis showed \u3b1-pinene and bicyclogermacrene as major constituents of OEPm, whereas \u3b1-muurolol was the main compound of OEEb. Both OEEb and OEPm showed MIC 65 512 \u3bcg/mL against the strains under study. However, the association of these oils with the blue LED light enhanced the action of the aminoglycosides amikacin and gentamicin. In conclusion, the association of aminoglycosides with the blue LED light and essential oils was effective against resistant bacteria

    Luminescence characteristics of quartz from Brazilian sediments and constraints for OSL dating

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    This study analyzes the optically stimulated luminescence (OSL) characteristics of quartz grains from fluvial, eolian and shallow marine sands of northeastern and southeastern Brazil, with especial focus on the applicability of the single-aliquot regenerative dose (SAR) dating protocol. All analyzed Brazilian sediments presented relatively high OSL sensitivity and good behavior regarding their luminescence characteristics relevant for radiation dose estimation. However, some samples from the Lençóis Maranhenses region in northeastern Brazil showed inadequate OSL sensitivity correction, hampering the implementation of the SAR protocol and their ability to behave as a natural dosimeter. While the shallow marine and eolian samples showed a narrow and reliable dose distribution, the fluvial sample had a wide dose distribution, suggesting incomplete bleaching and natural doses estimates dependent on age models

    TNF signalling drives expansion of bone marrow CD4+ T cells responsible for HSC exhaustion in experimental visceral leishmaniasis

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    Visceral leishmaniasis is associated with significant changes in hematological function but the mechanisms underlying these changes are largely unknown. In contrast to naïve mice, where most long-term hematopoietic stem cells (LT-HSCs; LSK CD150+ CD34- CD48- cells) in bone marrow (BM) are quiescent, we found that during Leishmania donovani infection most LT-HSCs had entered cell cycle. Loss of quiescence correlated with a reduced self-renewal capacity and functional exhaustion, as measured by serial transfer. Quiescent LT-HSCs were maintained in infected RAG2 KO mice, but lost following adoptive transfer of IFNγ-sufficient but not IFNγ-deficient CD4+ T cells. Using mixed BM chimeras, we established that IFNγ and TNF signalling pathways converge at the level of CD4+ T cells. Critically, intrinsic TNF signalling is required for the expansion and/or differentiation of pathogenic IFNγ+CD4+ T cells that promote the irreversible loss of BM function. These finding provide new insights into the pathogenic potential of CD4+ T cells that target hematopoietic function in leishmaniasis and perhaps other infectious diseases where TNF expression and BM dysfunction also occur simultaneously
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