775 research outputs found

    Evaluación de las propiedades físico-mecánicas de morteros de albañilería producidos en base de cemento y cal con áridos reciclados mixtos

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    This study investigated the physical-mechanical effects of cement-lime mortars containing recycled aggregate of construction and demolition waste (CDW). The natural aggregate (NA) was replaced by volume at 25%, 50%, 75% and 100% by mixed recycled aggregate (MRA) obtained from the CDW crushing. Five types of mortars were prepared with a volumetric ratio of 1:1:6 (cement, lime and aggregate) and water/binder ratio based on the fixed consistency of 260 mm. The effects of MRA on fresh and hardened mortars’ properties were analyzed. The results were analyzed using a one-way ANOVA. MRA incorporation improved most of the physical-mechanical properties of mortars tested, except for hardened bulk density, water absorption and porosity. In the long-run, mechanical strengths significantly increased in all compositions, especially those with higher percentages of MRA. The results obtained showed that the use of MRA in masonry mortars is an alternative to reduce the generation of waste and consumption of natural resources.Este estudio investigó los efectos físico-mecánicos de los morteros de cemento y cal con áridos reciclados de residuos de construcción y demolición (RCD). El árido natural (AN) se reemplazó en volumen al 25%, 50%, 75% y 100% por el árido reciclado mixto (ARM) obtenido de la trituración de RCD. Se prepararon cinco tipos de morteros con una relación volumétrica de 1: 1: 6 (cemento, cal y áridos) y una relación de agua / aglomerante en función de la consistencia fija de 260 mm. Se analizaron los efectos del ARM en las propiedades de los morteros frescos y endurecidos. Los resultados se analizaron utilizando un ANOVA-simple. La incorporación de ARM mejoró la mayoría de las propiedades físico-mecánicas de los morteros, excepto la densidad aparente endurecida, la absorción de agua y la porosidad. A largo plazo, las resistencias mecánicas aumentaron significativamente en todas las composiciones, especialmente en aquellas con porcentajes más altos de ARM. Los resultados obtenidos mostraron que el uso de ARM en morteros de albañilería es una alternativa para reducir la generación de residuos y el consumo de recursos naturales

    Coupling of Cyclic Voltammetry and Electrochemical Impedance Spectroscopy for Probing the Thermodynamics of Facilitated Ion Transfer Reactions Exhibiting Chemical Kinetic Hindrances

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    Mathematical models under conditions of cyclic staircase voltammetry and electrochemical impedance spectroscopy (EIS), which consider the kinetic effects due to the complexation reaction by the facilitated transfer of metal ions at polarized interfaces, are presented. Criteria for qualitative recognition of these kinetic effects from the features of simulated cyclic voltammograms are given. In case of the existence of these effects, only the EIS can bring access to the thermodynamics and kinetics of the complexation chemical reaction. Analytical equations for estimating the thermodynamic parameters by such systems under EIS conditions are evaluated. The theoretical results are compared with the experimental results of the facilitated Cu2+ transfer at the polarized water-1,2-dichlorethane interface, assisted by two phenanthroline-containing macrocycles. In the experimental case where kinetic effects due to the complexation step exist, we show how elegantly EIS can be used as a tool for estimation of the complexation constant of Cu2+ and 5-oxo-2,8-dithia [9],(2,9)-1,10-phenanthrolinophane (PhenOS2)

    Compact Groups analysis using weak gravitational lensing II: CFHT Stripe 82 data

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    In this work we present a lensing study of Compact Groups (CGs) using data obtained from the high-quality Canada-France-Hawaii Telescope Stripe 82 Survey. Using stacking techniques we obtain the average density contrast profile. We analyse the lensing signal dependence on the groups' surface brightness and morphological content, for CGs in the redshift range z = 0.2-0.4.We obtain a larger lensing signal for CGs with higher surface brightness, probably due to their lower contamination by interlopers. Also, we find a strong dependence of the lensing signal on the group concentration parameter, with the most concentrated quintile showing a significant lensing signal, consistent with an isothermal sphere with σV = 336 ± 28 km s-1 and a NFW profile with R200 = 0.60 ± 0.05 h-1 70 Mpc. We also compare lensing results with dynamical estimates finding a good agreement with lensing determinations for CGs with higher surface brightness and higher concentration indexes. On the other hand, CGs that are more contaminated by interlopers show larger dynamical dispersions, since interlopers bias dynamical estimates to larger values, although the lensing signal is weakened.Fil: Chalela Garcia, Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomía Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomía Teórica y Experimental; ArgentinaFil: Gonzalez, Elizabeth Johana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomía Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomía Teórica y Experimental; ArgentinaFil: Makler, Martín. Centro Brasileiro de Pesquisas Físicas; BrasilFil: Garcia Lambas, Diego Rodolfo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomía Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomía Teórica y Experimental; ArgentinaFil: Pereira, Maria E.S.. Centro Brasileiro de Pesquisas Físicas; BrasilFil: O'Mill, Ana Laura. Instituto de Astronomia Teorica y Experimental; ArgentinaFil: Shan, Huan Yuan. Argelander-Institut fur Astronomie; Alemani

    Evaluation of high-concentrate diets that vary in physically effective neutral detergent fibre for finishing lambs

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    The objective of this research was to evaluate lamb diets with a high proportion of concentrate and various levels of physically effective neutral detergent fibre (NDF) using tropical ingredients. Four diets were formulated: D1 with 16.5% physically effective NDF (peNDF), D2 with 21.4% peNDF, D3 with 23.3% peNDF, and D4 with 24.6% peNDF. Twenty male Santa Inês lambs at four months old with an average liveweight (LW) of 18.6 ± 3.4 kg were fed for 49 days. There were no differences (P >0.05) among the diets in dry matter (DM) intake. Crude protein (CP) intake, relative to either LW or metabolic live weight (LW0.75) or LW, was greater (P ≤0.05) for D2 and D3 than for D1 or D4. Lower (P ≤0.05) NDF intake, relative to LW0.75 or LW, was lower for D1 than for the other diets. Selection indexes (SIs) were similar (P >0.05) among diets. Animals that consumed D1 had less (P ≤0.05) rumination time per bolus. Meaningful variations were not observed in performance and efficiency of finishing lambs that were related to differences in peNDF among the diets. Santa Inês lambs were able to adapt to diets with low levels of peNDF by increasing rumination time as a consequence of increased fibre consumption and greater particle size selection

    Association Of Lipophilic Opioids And Hyperbaric Bupivacaine In Spinal Anesthesia For Elective Cesarean Section. Randomized Controlled Study

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    PURPOSE: To evaluate the efficacy and side-effects of fentanyl and sufentanil combined with hyperbaric spinal bupivacaine in elective cesarean section.METHODS: A prospective, randomized, double-blind study with 64 term parturients, distributed into 2 groups according to the opioid combined with hyperbaric bupivacaine 0.5% (10mg): GF - fentanyl (25μg) and GS - sufentanil (5.0μg). The latency and maximum sensory block level; degree and duration of motor block; duration and quality of analgesia; maternal-fetal repercussions were evaluated. This was an intention-to-treat analysis with a 5% significance level.RESULTS: The latency period, maximum sensory block level, motor block degree and perioperative analgesia were similar in both groups. Motor block and analgesia had a longer duration in the sufentanil group. Maternal adverse effects and neonatal repercussions were similar. The incidence of hypotension was higher in the fentanyl group. In both groups, there was a predominance of patients who were awake and either calm or sleepy.CONCLUSIONS: The addition of fentanyl and sufentanil to hyperbaric subarachnoid bupivacaine was shown to be effective for the performance of cesarean section, and safe for the mother and fetus. Analgesia was more prolonged with sufentanil.2911752758Dahlgren, G., Hultstrand, C., Jakobsson, J., Norman, M., Eriksson, E.W., Martin, H., Intrathecal sufentanil, fentanyl, or placebo added to bupivacaine for cesarean section (1997) Anesth Analg, 85 (6), pp. 1288-1293. , Dec, PMID: 9390596Dyer, R.A., Joubert, I.A., Low-dose spinal anaesthesia for Caesarean section (2004) Curr Opin Anaesthesiol, 17 (4), pp. 301-308. , 2004 Aug, PMID: 17021569Arzola, C., Wieczorek, P.M., Efficacy of low-dose bupivacaine in spinal anaesthesia for Caesarean delivery: Systematic review and meta-analysis (2011) Br J Anaesth, 107 (3), pp. 308-318. , Sep, Epub 2011 Jul 14Braga Ade, F., Frias, J.A., Braga, F.S., Pereira, R.I., Titotto, S.M., Spinal anesthesia for elective ceasarean section: Use of different doses of hyperbaric bupivacaine associated with morphine and clonidine (2013) Acta Cir Bras, 28 (1), pp. 26-32. , Jan, PMID: 23338110Braga Ade, F., Braga, F.S., Potério, G.M., Pereira, R.I., Reis, E., Cremonesi, E., Sufentanil added to hyperbaric bupivacaine for subarachnoid block in Caesarean section (2003) Eur J Anaesthesiol, 20 (8), pp. 631-635. , Aug, PMID: 12932064Braga Ade, F., Frias, J.A., Braga, F.S., Pinto, D.R., Spinal block with 10 mg of hyperbaric bupivacaine associated with 5 microg of sufentanil for cesarean section. Study of different volumes (2010) Rev Bras Anestesiol, 60 (2), pp. 121-129. , Mar-Apr, PMID: 20485956Karaman, S., Kocabas, S., Uyar, M., Hayzaran, S., Firat, V., The effects of sufentanil or morphine added to hyperbaric bupivacaine in spinal anaesthesia for caesarean section (2006) Eur J Anaesthesiol, 23 (4), pp. 285-291. , Apr, PMID: 16438758Braga, A.A., Frias, J.A., Braga, F.S., Potério, G.B., Hirata, E.S., Torres, N.A., Spinal anesthesia for cesarean section. Use of hyperbaric bupivacaine (10mg) combined with different adjuvants (2012) Rev Bras Anestesiol, 62 (6), pp. 775-787. , Nov-Dec, PMID: 23176986Karaman, S., Günüsen, I., Uyar, M., Biricik, E., Fırat, V., The effects of morphine and fentanyl alone or in combination added to intrathecal bupivacaine in spinal anesthesia for cesarean section (2011) Agri, 23 (2), pp. 57-63. , Apr, PMID: 21644105Filos, K.S., Goudas, L.C., Patroni, O., Polyzou, V., Intrathecal clonidine as a sole analgesic for pain relief after cesarean section (1992) Anesthesiology, 77 (2), pp. 267-274. , Aug, PMID: 1642346Braz, J.R., Koguti, E.S., Braz, L.G., Croitor, L.B., Navarro, L.H., Effects of clonidine associated to hyperbaric bupivacaine during high-level spinal anesthesia (2003) Rev Bras Anestesiol, 53 (5), pp. 561-572. , Sep, PMID: 19475309Hamber, E.A., Viscomi, C.M., Intrathecal lipophilic opioids as adjuncts to surgical spinal anesthesia (1999) Reg Anesth Pain Med, 24, pp. 255-263. , May- Jun, PMID: 10338179Abouleish, E., Rawal, N., Fallon, K., Hernandez, D., Combined intrathecal morphine and bupivacaine for cesarean section (1988) Anesth Analg, 67 (4), pp. 370-374. , Apr, PMID: 3354872Abouleish, E., Apnoea associated with the intrathecal administration of morphine in obstetrics. 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    Localization of coated iron oxide (Fe3O4) nanoparticles on tomato seeds and their effects on growth

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    IFood demand due to the growing population globally has been stretching the agriculture sector to the limit. This demands the cultivation of plants in shrinking land areas which makes the search for highly effective systems for plant nutrition and pest control important. In this context, the application of nanoparticles (NPs) in agriculture can have a transformative effect on food production techniques as it can enable the delivery of bioactive agents (including growth factors, pesticides and fungicides) directly to plants. Herein we report the application of unfunctionalized as well as amine-functionalized and polycaprolactone-coated Fe3O4 nanoparticles (NP) to seed treatment and plant growth. The study reveals that the treatment has no side effects on plant germination and development. Furthermore, the penetration of NPs in tomato seeds (Solanum Lycopersicum) and their translocation in tomato seedlings post-treatment depends on the level of the NPs functionalization. The research also demonstrates that a fraction of NP is preferentially translocated to tomato seedling roots and shoots, however, uptake is lower for functionalized NPs (both amine and PCL). Thus, the results suggest that the functionalization of NPs can act as a versatile platform for delivering of active compounds, such as fungicides and growth factor agents
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