535 research outputs found

    Internal friction in advanced Fe-Al intermetallics

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    We have measured the internal friction and the dynamic modulus of an Fe–38 at.% Al alloy using a forced torsion pendulum working between 10−3 and 10 Hz. The measurements have been carried out as a function of temperature (from room temperature to 1200 K) and as a function of frequency. Two peaks have been observed in the internal friction spectra, at about 780 and 1100 K, which are largely superposed in the intermediate temperature range. Both peaks and the corresponding modulus defect shift in temperature with the oscillation frequency, and can be attributed to relaxation mechanisms. Previous results in the literature seem to indicate that the low temperature peak is the Zener relaxation of Al atoms. The activation energy of the high-temperature peak, referred to as P1 peak because it has not been studied previously, has been determined to be Hact = 2.87 eV, from the results of measurements at different temperatures and frequencies. We discuss the possible mechanisms, which could be responsible of this P1 peak, and suggest that it could be attributed to the intrinsic movements of left angle bracket1 0 0right-pointing angle bracket perfect dislocations over the Peierls barrier by kink pair formation in the B2 ordered FeAl

    Staphylococcus aureus poststernotomy mediastinitis: Description of two distinct acquisition pathways with different potential preventive approaches

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    ObjectiveDetermining the acquisition routes of infection is crucial to designing specific preventive approaches against Staphylococcus aureus poststernotomy mediastinitis.MethodsFrom 2002 to 2004, a nasal sample was obtained from patients before cardiac surgery. We collected clinical and microbiologic data of all episodes of S aureus poststernotomy mediastinitis. A case–control study (3:1) was performed to confirm the role of previous preoperative nasal colonization by S aureus as a risk factor for S aureus poststernotomy mediastinitis. Pulsed field gel electrophoresis molecular analysis of nasal and surgical site S aureus isolates was performed to analyze their relatedness in each patient with poststernotomy mediastinitis and with other patients of the study cohort.ResultsS aureus nasal cultures were positive in 228 (15.9%) of 1432 patients: methicillin-susceptible S aureus in 222 (15.5%) and meticillin-resistant S aureus in 6 (0.4%). S aureus poststernotomy mediastinitis was diagnosed in 17 (1.2%) of 1432 patients: 9 (3.95%) of 228 in colonized patients versus 8 (0.66%) of 1204 in noncolonized patients (P < .0001). Seven of 9 patients (1.2%) with methicillin-susceptible S aureus had an identical isolate by pulsed field gel electrophoresis in preoperative nasal and surgical-site cultures, but no clonal relatedness was shown among the isolates from these 9 patients. None of the 8 patients with methicillin-resistant S aureus poststernotomy mediastinitis had an identical isolate by pulsed field gel electrophoresis in preoperative nasal and surgical-site cultures, and the same clone of methicillin-resistant S aureus was responsible for all these cases.ConclusionsNasal colonization often precedes methicillin-resistant S aureus poststernotomy mediastinitis, which suggests that decontamination is adequate for preventing methicillin-resistant S aureus poststernotomy mediastinitis, whereas hospital infection control measures seem to be the major factor for preventing methicillin-resistant S aureus poststernotomy mediastinitis

    Drying of wastes of almond shells in conical spouted beds

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    [EN] The goal of this study was to prove the feasibility of a conical spouted bed dryer for the drying of wastes of almond tree fruit. The drying operating regimes ranges in sspouted beds contactors were determined. The drying tests were conducted in the spouted bed regime under determined experimental conditions. Beds consisting of almond shells were dried at drying air temperatures ranging from room temperature to 140 ºC. The drying behaviour was assessed based on the decrease in moisture content of almond shells with the time and the effect of drying air temperature on the drying process was analyzed.This work was performed with financial support from the Spanish Ministry of Economy and Competitiveness and co-funded by the European Union through ERDF funds (Project CTQ2014-59312-P and Project CTQ2017-89199-P).San Jose, MJ.; Alvarez, S.; Lopez, R. (2018). Drying of wastes of almond shells in conical spouted beds. En IDS 2018. 21st International Drying Symposium Proceedings. Editorial Universitat Politècnica de València. 857-864. https://doi.org/10.4995/IDS2018.2018.7490OCS85786

    Evaluacion del desempeno exportador de dos Pymex de la Región del Maule, basada en cinco variables claves

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    83 p.La positiva evolución del sector externo de nuestro país, se ha caracterizado por la apertura de nuevos mercados y la entrada de un mayor número de PYMEX (Pequeña y Mediana Empresa Exportadora) en los mercados internacionales, éstas constituyen el 65% del total de empresas exportadoras del país en el primer trimestre de este año, esto de acuerdo a la Cámara de Comercio de Santiago (C.C.S). Sin embargo, existe un bajo desempeño exportador de las PYMEX en la Región del Maule, en relación al promedio; algunas de estas empresas han tenido un decrecimiento importante en los últimos años, lo que entrega indicios de la existencia de una falla en su administración. En base a esto, el propósito de esta investigación fue evaluar el desempeño exportador de dos PYMEX de características similares de la Región del Maule, basándonos en la gestión que han hecho dichas empresas de 5 variables claves del éxito extraídas de un estudio realizado anteriormente. Hemos realizado una investigación cualitativa, cuya estrategia de diseño fue el estudio de casos. El estudio consistió en tomar una empresa de crecimiento positivo en sus exportaciones entre los años 1999 y 2003, nombrada como Empresa A, y una empresa con un decrecimiento en sus exportaciones, durante el mismo período de tiempo, la que llamamos Empresa B. Se confeccionó un esquema conceptual en base a una exhaustiva revisión bibliográfica, en el cual aparece toda la información fundamental para evaluar la gestión de cada una de las cinco variables claves. Entramos en cada una de estas dos empresas y averiguamos cada uno de los puntos de nuestro esquema conceptual, luego ordenamos la información y analizamos los resultados. Quedando claramente reflejado que la Empresa A gestiona mucho mejor sus 5 variables claves de éxito exportador, con respecto a la Empresa B. Lo que marca la diferencia en la evolución de las exportaciones de las dos empresas en los últimos 5 años

    Dendron-functionalised hyperbranched bis-MPA polyesters as efficient non-viral vectors for gene therapy in different cell lines

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    Gene therapy has become a relevant tool in the biomedical field to treat or even prevent some diseases. The effective delivery of genetic material into the cell remains a crucial step to succeed in this purpose. In the search for efficient non-viral vectors, a series of amino-terminated dendronized hyperbranched polymers (DHPs) of different generations based either on bis-MPA or bis-GMPA have been designed. All of them have demonstrated an accurate ability to complex two types of genetic materials, a plasmid DNA and a siGFP, yielding dendriplexes. Moreover, some of them have proved to be able to deliver the genetic material inside the cells, resulting in the effective accomplishment of the desired genetic modification and improving the activity of some commercial transfection reagents. Different cell lines, including cancer and mesenchymal stem cells, have been studied here to evaluate the ability of DHPs as vectors for transfection. Treatments based on mesenchymal stem cells are gaining importance due to their pluripotency. Thus, it is of special relevance to introduce a genetic modification into a mesenchymal cell line as it allows it to act over a wide spectrum of tissues after inducing cellular differentiation

    One-Pot Synthesis of Polycyclic Nucleosides with Unusual Molecular Skeletons

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    An R hydroxy pyrrolidine tricyclic nucleoside 3 and its spontaneous reaction with acetone is described. In this transformation highly functionalized polycyclic nucleosides with rather unusual molecular skeletons are formed in a complete regio-and stereoselective way. The reaction involves the formation of three new bonds, two of them novel carbon-carbon bonds, in a one-pot way. An enamine-iminium mechanism with participation of carbinolamine, iminium ion, and enamine intermediates is proposed as a plausible explanation for this transformation. The scope of the reaction is briefly studied concluding that the nature of the ketone (R1COR2) is critical for the initial attack of the NH to the carbonyl group.We thank Susana Ruiz for excellent technical assistance. The Spanish MEC/MCINN (project SAF 2006-12713-C02-01) and the Comunidad de Madrid (project BIPEDD-CM S-B10-0214-2006) are also acknowl- edged for financial support. The Spanish Consejo Superior de Investigaciones Cientı´ ficas is also acknowledged for a JAE-Doc contract to M.-C.B.Peer reviewe

    Daptomycin Plus Fosfomycin Versus Daptomycin Alone for Methicillin-resistant Staphylococcus aureus Bacteremia and Endocarditis: A Randomized Clinical Trial

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    Bacteremia; Daptomycin; FosfomycinBacterièmia; Daptomicina; FosfomicinaBacteriemia; Daptomicina; FosfomicinaBackground We aimed to determine whether daptomycin plus fosfomycin provides higher treatment success than daptomycin alone for methicillin-resistant Staphylococcus aureus (MRSA) bacteremia and endocarditis. Methods A randomized (1:1) phase 3 superiority, open-label, and parallel group clinical trial of adult inpatients with MRSA bacteremia was conducted at 18 Spanish hospitals. Patients were randomly assigned to receive either 10 mg/kg of daptomycin intravenously daily plus 2 g of fosfomycin intravenously every 6 hours, or 10 mg/kg of daptomycin intravenously daily. Primary endpoint was treatment success 6 weeks after the end of therapy. Results Of 167 patients randomized, 155 completed the trial and were assessed for the primary endpoint. Treatment success at 6 weeks after the end of therapy was achieved in 40 of 74 patients who received daptomycin plus fosfomycin and in 34 of 81 patients who were given daptomycin alone (54.1% vs 42.0%; relative risk, 1.29 [95% confidence interval, .93–1.8]; P = .135). At 6 weeks, daptomycin plus fosfomycin was associated with lower microbiologic failure (0 vs 9 patients; P = .003) and lower complicated bacteremia (16.2% vs 32.1%; P = .022). Adverse events leading to treatment discontinuation occurred in 13 of 74 patients (17.6%) receiving daptomycin plus fosfomycin, and in 4 of 81 patients (4.9%) receiving daptomycin alone (P = .018). Conclusions Daptomycin plus fosfomycin provided 12% higher rate of treatment success than daptomycin alone, but this difference did not reach statistical significance. This antibiotic combination prevented microbiological failure and complicated bacteremia, but it was more often associated with adverse events.This work was supported by the Spanish Ministry of Science, Innovation and Universities (PI12/01907); Spanish Network for Research in Infectious Diseases (RD16/0016/0005); Instituto de Salud Carlos III (ISCIII); and Spanish Ministry of Economy, Industry and Competitiveness. This work was also supported by the European Development Regional Fund “A way to achieve Europe,” Operational Programme Intelligent Growth 2014–2020; Spanish Clinical Research Network (SCReN), co-financed by the Plan Nacional de I+D and ISCIII, Subdirección General de Evaluación y Fomento de la Investigación (PT13/0002/0007); and the Grupo de Estudio de la Infección Relacionada con la Asistencia Sanitaria. J. M.-M. received a personal 80:20 research grant from the Institut d’Investigacions Biomèdiques Agust Pi i Sunyer, Barcelona, Spain, during 2017–2021
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