1,609 research outputs found

    Small-polaron hopping conductivity in bilayer manganite La1.2_{1.2}Sr1.8_{1.8}Mn2_{2}O7_{7}

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    We report anisotropic resistivity measurements on a La1.2_{1.2}Sr1.8_{1.8}Mn2_{2}O7_{7} single crystal over a temperature TT range from 2 to 400 K and in magnetic fields HH up to 14 T. For T≄218T\geq 218 K, the temperature dependence of the zero-field in-plane ρab(T)\rho_{ab}(T) resistivity obeys the adiabatic small polaron hopping mechanism, while the out-of-plane ρc(T)\rho_{c}(T) resistivity can be ascribed by an Arrhenius law with the same activation energy. Considering the magnetic character of the polarons and the close correlation between the resistivity and magnetization, we developed a model which allows the determination of ρab,c(H,T)\rho_{ab,c}(H,T). The excellent agreement of the calculations with the measurements indicates that small polarons play an essential role in the electrical transport properties in the paramagnetic phase of bilayer manganites.Comment: 4 pages, 3 figures, to appear in Physical Review

    Synthesis and Biological Evaluation of Modified 2-Deoxystreptamine Dimers

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    Aminoglycosides are powerful antibiotics, but the emergence of resistant bacterial strains has prompted the search for analogues with better pharmacological profiles. The synthesis of 2-deoxystreptamine (2-DOS) dimers linked by polyamines and analogues based on furylcarbopeptoid skeletons is described. Potent and selective ligands for bacterial 16S rRNA were identified using microarray techniques by determining the affinity of these derivatives toward bacterial and human ribosomal RNA

    Ultrasonic evidence of an uncorrelated cluster formation temperature in manganites with first-order magnetic transition at T_C

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    Ultrasonic attenuation and phase velocity measurements have been carried out in the ferromagnetic perovskites La_{2/3}Ca_{1/3}MnO_3 and La_{2/3}Sr_{1/3}MnO_3. Data show that the transition at the Curie temperature, T_C, changes from first- to second-order as Sr replaces Ca in the perovskite. The compound with first-order transition shows also another transition at a temperature T* > T_C. We interpret the temperature window T_C < T < T* as a region of coexistence of a phase separated regime of metallic and insulating regions, in the line of recent theoretical proposals.Comment: 4 pages, 2 figure

    Extracorporeal immune therapy with immobilized agonistic anti-Fas antibodies leads to transient reduction of circulating neutrophil numbers and limits tissue damage after hemorrhagic shock/resuscitation in a porcine model

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    Background: Hemorrhagic shock/resuscitation is associated with aberrant neutrophil activation and organ failure. This experimental porcine study was done to evaluate the effects of Fas-directed extracorporeal immune therapy with a leukocyte inhibition module (LIM) on hemodynamics, neutrophil tissue infiltration, and tissue damage after hemorrhagic shock/resuscitation. Methods: In a prospective controlled double-armed animal trial 24 Munich Mini Pigs (30.3 +/- 3.3 kg) were rapidly haemorrhaged to reach a mean arterial pressure (MAP) of 35 +/- 5 mmHg, maintained hypotensive for 45 minutes, and then were resuscitated with Ringer's solution to baseline MAP. With beginning of resuscitation 12 pigs underwent extracorporeal immune therapy for 3 hours (LIM group) and 12 pigs were resuscitated according to standard medical care (SMC). Haemodynamics, haematologic, metabolic, and organ specific damage parameters were monitored. Neutrophil infiltration was analyzed histologically after 48 and 72 hours. Lipid peroxidation, and apoptosis were specifically determined in lung, bowel, and liver. Results: In the LIM group, neutrophil counts were reduced versus SMC during extracorporeal immune therapy. After 72 hours, the haemodynamic parameters MAP and cardiac output (CO) were significantly better in the LIM group. Histological analyses showed reduction of shock-related neutrophil tissue infiltration in the LIM group, especially in the lungs. Lower amounts of apoptotic cells and lipid peroxidation were found in organs after LIM treatment. Conclusions: Transient Fas-directed extracorporeal immune therapy may protect from posthemorrhagic neutrophil tissue infiltration and tissue damage

    ICOS costimulation at the tumor site in combination with CTLA-4 blockade therapy elicits strong tumor immunity

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    Cytotoxic T lymphocyte-associated protein 4 (CTLA-4) blockade therapy is able to induce long-lasting antitumor responses in a fraction of cancer patients. Nonetheless, there is still room for improvement in the quest for new therapeutic combinations. ICOS costimulation has been underscored as a possible target to include with CTLA-4 blocking treatment. Herein, we describe an ICOS agonistic aptamer that potentiates T cell activation and induces stronger antitumor responses when locally injected at the tumor site in combination with anti-CTLA-4 antibody in different tumor models. Furthermore, ICOS agonistic aptamer was engineered as a bi-specific tumor-targeting aptamer to reach any disseminated tumor lesions after systemic injection. Treatment with the bi-specific aptamer in combination with CTLA-4 blockade showed strong antitumor immunity, even in a melanoma tumor model where CTLA-4 treatment alone did not display any significant therapeutic benefit. Thus, this work provides strong support for the development of combinatorial therapies involving anti-CTLA-4 blockade and ICOS agonist tumor-targeting agents

    Dietary Intake, Nutritional Adequacy and Food Sources of Total Fat and Fatty Acids, and Relationships with Personal and Family Factors in Spanish Children Aged One to <10 Years: Results of the EsNuPI Study

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    We aimed to determine the usual intake of total fat, fatty acids (FAs), and their main food sources in a representative cohort of the Spanish pediatric population aged 1 to <10 years (n = 707) who consumed all types of milk and an age-matched cohort who consumed adapted milk over the last year (including follow-on formula, toddler’s milk, growing-up milk, and fortified and enriched milks) (n = 741) who were participants in the EsNuPI study (in English, Nutritional Study in the Spanish Pediatric Population). Dietary intake, measured through two 24 h dietary recalls, was compared to the European Food Safety Authority (EFSA) and the Food and Agriculture Organization of the United Nations (UN-FAO) recommendations. Both cohorts showed a high intake of saturated fatty acids (SFAs), according to FAO recommendations, as there are no numerical recommendations for SFAs at EFSA. Also, low intake of essential fatty acids (EFAs; linoleic acid (LA) and α-linolenic acid (ALA)) and long-chain polyunsaturated fatty acids (LC-PUFA) of the n-3 series, mainly docosahexaenoic acid (DHA) were observed according to EFSA and FAO recommendations. The three main sources of total fat and different FAs were milk and dairy products, oils and fats, and meat and meat products. The consumption of adapted milk was one of the main factors associated with better adherence to the nutritional recommendations of total fat, SFAs, EFAs, PUFAs; and resulted as the main factor associated with better adherence to n-3 fatty acids intake recommendations. Knowledge of the dietary intake and food sources of total fat and FAs in children could help in designing and promoting effective and practical age-targeted guidelines to promote the consumption of EFA- and n-3 PUFA-rich foods in this stage of life
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