909 research outputs found

    Palaeoenvironmental turnover across the Cenomanian-Turonian transition in Oued Bahloul, Tunisia: Foraminifera and geochemical proxies

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    The integrated analysis of foraminiferal assemblages, geochemical proxies, and stable isotopes in the Oued Bahloul section (Tunisia) allowed us to reconstruct the environmental turnover across the Cenomanian–Turonian boundary. An increase in palaeoproductivity proxies (P/Ti, U/Al, Sr/Al) and in d13C values, and a decrease in foraminiferal diversity and d18O values mark the beginning of the Oceanic Anoxic Event 2 (OAE2) at the Rotalipora cushmani and Whiteinella archaeocretacea biozones boundary. Eutrophic conditions at the seafloor and in the water column are evidenced by high proportions of buliminids and the replacement of planktic oligotrophic specialist Rotalipora by eutrophic opportunist Hedbergella. The enrichment in organic matter and redox sensitive elements, together with the abundance of low-oxygen tolerant benthic foraminifera, indicate dysoxic conditions in the deep-water column and at the seafloor (higher Uaut than Moaut). Among planktic foraminifera, deep- and intermediate-dwellers disappear (Rotalipora and Globigerinelloides), and surface-dwellers proliferate (Hedbergella). The persistency of the poorly oxygenated conditions during the W. archaeocretacea Biozone locally produced euxinic conditions where MoEF and Moaut reach high values, diversity presents minimum values, and benthic foraminifera temporarily disappear. The maximum percentage of heterohelicids indicates a stratified water column with a well-developed oxygen minimum zone. Improved oxygen conditions returned in the upper part of the W. archaeocretacea Biozone and Helvetoglobotruncana helvetica Biozone, with a slow recovery of foraminiferal assemblages, decrease in eutrophic genera (Heterohelix) and increase in mesotrophic genera (Whiteinella). A gradual increase in d18O values suggests decreased temperatures in surface waters. The OAE2 has been attributed to global temperature changes and palaeoceanographic reorganization. The poor mixing of surface and deep waters and enhanced primary productivity related to global warming – associated with increasing continental weathering and nutrient runoff – may have favored the eutrophication of the ocean and the expansion of the oxygen minimum zone

    Thermal and Dielectric Characterization of Multi-Walled Carbon NanotubesThermoplastic Polyurethanes Composites

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    [EN] Multi-walled carbon nanotubes-thermoplastic polyurethanes composites were characterized by means of differential scanning calorimetry and dielectric relaxation spectroscopy. The composite is characterized by two glass transition temperatures T (g) . The T (g) associated with the soft segment decreases by increasing of carbon nanotubes content, while carbon nanotubes content has practically no effect on the value of the T-g associated with the hard segments. It was observed that rising the temperature and carbon nanotubes content resulted in the increased of both the dielectric permittivity and the loss factor. The presence of carbon nanotubes produces an enhancement of charge carriers trapping, increasing the electrical conductivity. The electrical conductivity of the composite was found to exhibit an insulator to conductor transition at a carbon nanotubes critical content, i.e., the percolation threshold, near 6 wt %.MJS and MC acknowledge the financial support of the DGCYT through Grant MAT2015-63955-R.Sanchis Sánchez, MJ.; Carsí Rosique, M.; Gracia-Fernandez, C. (2017). Thermal and Dielectric Characterization of Multi-Walled Carbon NanotubesThermoplastic Polyurethanes Composites. Polymer Science Series A. 59(4):543-553. https://doi.org/10.1134/S0965545X17040083S543553594D. W. Schaefer and R. S. Justice, Macromolecules 40 (24), 8501 (2007).D. R. Raul and L. M. Robeson, Polymer 49 (15), 3187 (2008).P. J. Brigandi, J. M. Cogen, and R. A. Pearson, Polym. Eng. Sci. 54 (1), 1 (2014).H. Deng, L. Lin, M. Ji, S. Zhang, M. Yang, and Q. Fu, Prog. Polym. Sci. 39 (4), 627 (2014).Polymer-Matrix Composites. Types, Applications and Performance, Ed. by R. Kumar (Nova Sci. Publ., New York, 2014).Z. Wenying and Y. Demei, J. Appl. Polym. Sci. 118 (6), 3156 (2010).Y. P. Mamunya, V. V. Davydenko, P. Pissis, and E. V. Lebedev, Eur. Polym. J. 38 (9), 1887 (2002)B. Redondo-Foj, P. Ortiz-Serna, M. Carsí, M. J. Sanchis, M. Culebras, C. M. Gomez, and A. Cantarero, Polym. Int. 64, 284 (2015).S. Deng, Y. Zhu, X. Qi, W. Yu, F. Chen, and Q. Fu, RSC Adv. 6 (51), 45578 (2016).M. Khissi, M. El Hasnaoui, J. Belattar, M. P. F. Graca, M. E. Achour, and L. C. Costa, J. Mater. Environ. Sci. 2 (3), 281 (2011).M. Hindermann-Bischoff and F. Ehrburger-Dolle, Carbon 39 (3), 375 (2001).I. Balberg, Carbon 40 (2), 139 (2002).M. Moniruzzaman and K. I. Winey, Macromolecules 39, 5194 (2006).A. Bharati, R. Cardinaels, J. W. Seo, M. Wubbenhorst, and P. Moldenaers, Polymer 79 (19), 271 (2015)Szycher's Handbook of Polyurethanes, Ed. by M. Szycher (CRC Press, Washington, DC, 1999).C. Prisacariu, Polyurethane Elastomers. From Morphology to Mechanical Aspects (Springer, New York, 2011).P. Król, Prog. Mater. Sci. 52 (6), 915 (2007).P. R. de C. Coelho Filho, M. S. Marchesin, A. R. Morales, and J. R. Bartoli, Mater. Res. 17 (1), 127 (2014).R. H. Baughman, A. A. Zakhidov, and W. A. de Heer, Science 297 (5582), 787 (2002).J. Kim and Y. Son, Polymer 88, 29 (2016)M. A. Nikje Mir and A. Yaghoubi, Polimery 59(11–12), 776 (2014).C. Kingston, R. Zepp, A. Andrady, D. Boverho, R. Fehir, D. Hawkins, J. Roberts, P. Sayre, B. Shelton, Y. Sultan, V. Vejins, and W. Wohlleben, Carbon 68, 33 (2014).Anelastic and Dielectric Effects in Polymeric Solids, Ed. by N. G. McCrum, B. E. Read, and G. Williams (Wiley, London, 1967).In Broadband Dielectric Spectroscopy, Ed. by F. Kremer, and A. Schonhals (Springer, Berlin, 2003).E. Riande and R. Diaz-Calleja, Electrical Properties of Polymers (Marcel Dekker, New York, 2004).I. M. Hodge, K. L. Ngai, and C. T. Moynihan, J. Non-Cryst. Solids 351 (2), 104 (2005).A. Eceiza, M.D. Martin, K. de la Caba, G. Kortaberria, N. Gabilondo, M. A. Corcuera, and I. Mondragon, Polym. Eng. Sci. 48 (2), 297 (2008)A. K. Jonscher, Universal Relaxation Law: A Sequel to Dielectric Relaxation in Solids (Chelsea Dielectrics Press, London, 1996), Chap. 5.A. K. Jonscher, Nature 267, 673 (1977).G. Li, L. Feng, P. Tong, and Z. Zhai, Prog. Org. Coat. 90, 284 (2016)K. Petrie, M. Kontopoulou, and A. Docoslis, Polym. Compos. 37 (9), 2794 (2016)N. Aranburu and J. I. Eguiazabal, Polym. Compos. 35 (3), 587 (2014)Impedance Spectroscopy. Theory, Experiment, and Applications, Ed. by E. Barsoukov and J. R. Macdonals (Wiley Intersci., New York, 2005).S. Havriliak and S. J. Havriliak, Dielectric and Mechanical Relaxation in Materials (Hanser, Munich, 1997), p. 57.S. Havriliak and S. Negami, Polymer 8 (4), 161 (1967)

    Applying MILP-based algorithms to automated job-shop scheduling problems in aircraft-part manufacturing

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    This work presents efficient algorithms based on Mixed-Integer Linear Programming (MILP) for complex job-shop scheduling problems raised in Automated Manufacturing Systems. The aim of this work is to find alternative solution approaches of production and transportation operations in a multi-product multistage production process that can be used to solve industrial-scale problems with reasonable computational effort. The MILP model developed must take into account; dissimilar recipes, single unit per production stage, re-entrant flows, sequence- dependent free transferring times and load transfer movements in a single automated material-handling device. In addition, logical-based strategies are proposed to iteratively find and improve the solutions generated over time. These approaches were tested in different real-world problems appeared in the surfacetreatment process of metal components in aircraft manufacturing industry.Sociedad Argentina de Informática e Investigación Operativ

    Applying MILP-based algorithms to automated job-shop scheduling problems in aircraft-part manufacturing

    Get PDF
    This work presents efficient algorithms based on Mixed-Integer Linear Programming (MILP) for complex job-shop scheduling problems raised in Automated Manufacturing Systems. The aim of this work is to find alternative solution approaches of production and transportation operations in a multi-product multistage production process that can be used to solve industrial-scale problems with reasonable computational effort. The MILP model developed must take into account; dissimilar recipes, single unit per production stage, re-entrant flows, sequence- dependent free transferring times and load transfer movements in a single automated material-handling device. In addition, logical-based strategies are proposed to iteratively find and improve the solutions generated over time. These approaches were tested in different real-world problems appeared in the surfacetreatment process of metal components in aircraft manufacturing industry.Sociedad Argentina de Informática e Investigación Operativ

    Applying MILP-based algorithms to automated job-shop scheduling problems in aircraft-part manufacturing

    Get PDF
    This work presents efficient algorithms based on Mixed-Integer Linear Programming (MILP) for complex job-shop scheduling problems raised in Automated Manufacturing Systems. The aim of this work is to find alternative solution approaches of production and transportation operations in a multi-product multistage production process that can be used to solve industrial-scale problems with reasonable computational effort. The MILP model developed must take into account; dissimilar recipes, single unit per production stage, re-entrant flows, sequence- dependent free transferring times and load transfer movements in a single automated material-handling device. In addition, logical-based strategies are proposed to iteratively find and improve the solutions generated over time. These approaches were tested in different real-world problems appeared in the surfacetreatment process of metal components in aircraft manufacturing industry.Sociedad Argentina de Informática e Investigación Operativ

    Control químico de malezas en cítricos

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    Se evaluó la efectividad y residualidad de algunos herbicidas en cultivos de cítricos en el sur del Departamento del Atlántico. Se empleó un diseño de bloques al azar con 3 replicaciones, empleando parcelas de 4 x 4 m. Para la evaluación de la fitotoxicidad al cultivo y residualidad de los productos, se tomaron datos quincenales del porcentaje de área cubierta de gramíneas como de malezas de hoja ancha, durante 330 días, habiéndose realizado 18 observaciones. Las parcelas fueron inicialmente desenmalezadas y limpiadas. Los tratamientos más promisorios por su buen control y residualidad larga para el control de malezas en cítricos, fueron los siguientes: Diuron (4 kg/ha), Terbacil (2 kg/ha), Atrazina (2 kg/ha) más Diuron (2 kg/ha), Atrazina (4 kg/ha) y Atrazina (2 kg/ha) más CP 50144 (2 kg/ha). Para el control de malezas de hoja ancha se recomienda aplicar: Amitrol T (4 kg/ha) y 2,4-D (2 kg/ha). Para controlar gramíneas: Pyriclor (1 kg/ha) y Dalapón (6 kg/ha). Se señala que el uso de Amitrol T, Paraquat, Dalapon, Pyriclor y 2,4-D requieren protección al follaje durante las aplicacione

    Synthesis of chitosan oligomers/propolis/silver-nanoparticles composite systems and study of their activity against Diplodia seriata

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    The synthesis and characterization of composites of oligomeric chitosan with propolis extract which allow the incorporation of a third component (silver nanoparticles) are reported, together with their application in aqueous or hydroalcoholic solutions with a view to the formation of adhesive substances or nanofilms for the protection of vineyards against harmful xylophagous fungi. The antimicrobial properties of the association of the two biological products or those resulting from the incorporation of silver nanoparticles (NPs) are studied and discussed. The efficacy of the chitosan oligomers/propolis/silver NPs ternary system is assessed in vitro for Diplodia fungi. A preliminary study on the convenience of replacing propolis with gentisic acid is also presented

    External stimuli help restore post-partum ovarian activity in Pelibuey sheep

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    Post-partum anestrus is a problem on farms, and its duration depends on the frequency and intensity of suckling which affects reproduction and production efficiency to become a determining economic factor. The aim of this study was to determine the post-partum reproductive response in ewe to a "male effect" with an ovulation induction protocol of five days using progesterone and the application of a metabolic restorative (MR; Metabolase ®). One hundred and twenty females were randomly assigned to one of four treatments: T1: Continuous suckling (CS; n = 29), T2: CS + MR (n = 29), T3: CS + Male Effect (ME; n = 32), and T4: CS + MR + ME. The percentage of females in ovulation, weight changes among females and lambs, the onset of estrus, calving, fecundity, and prolificacy were also determined. The ovulation percentage was higher in CS + ME and CS + MR + ME (75.0 and 73.3%) than in the other treatments. Weight changes in females and lambs were different among periods. The onset of estrus was similar for CS and CS + MR (25.9 ± 1.9 and 25.7 ± 0.7 h, respectively). The calving percentage was higher for CS + MR (86.2%) than other treatments. Male presence positively affected the postpartum cyclic ovarian re-establishment and the metabolic restorative could even improve the fertility of hair ewes in continuous suckling with similar hormone protocolKeywords: Male effect, metabolic stimulation, post-partum anestru

    “Male effect” and “temporary weaning” in synchronization of post-partum ovarian activity in Pelibuey ewes

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    To evaluate the response of the “male effect” and “temporary weaning” on the synchronization of post-partum ovarian activity in Pelibuey ewes, an experiment was carried out using 78 Pelibuey ewes with suckling lambs. The ewes were separated from their offspring for 48 hours and randomly assigned to one of four treatments derived from the arrangement of two factors, “male effect” and “temporary weaning”, each at two levels. Treatments were: T1 (n = 20) control ewes, without “male effect” and without “temporary weaning”); T2 (n = 19) ewes without “male effect” and with “temporary weaning”; T3 (n = 20) ewes with “male effect” and without “temporary weaning”; and T4 (n = 19), ewes with “male effect” and with “temporary weaning”. The response to oestrus, return to oestrus, gestation rate and lambing rate were analysed using logistic regression. The onset of oestrus was analysed using survival curves. No significant differences were found for lambing rate and prolificacy among treatments. “Temporary weaning” (T2) and “male effect” (T3) did not influence the response to oestrus, rate and duration of return to oestrus, or gestation rate and fertility, and was similar to the control group (T1). The interaction of “male effect” with “temporary weaning” (T4) increased the response to oestrus, reduced the rate and duration of return to oestrus, and the gestation rate, but increased fertility. Synchronizing post-partum ovarian activity with “male effect” and “temporary weaning” reduces the onset of oestrus and the rate of return to oestrus, but increases the response to oestrus and fecundity in Pelibuey ewes.Keywords: Biostimulation, progestogens, prolificacy, prostaglandins, sucklin

    Constituents of Quercus eduardii leaf infusion: Their interaction with gut microbiota communities and therapeutic role in colorectal cancer.

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    The infusion of Q. eduardii leaves has been used ancestrally for medicinal purposes. We investigated the effect of Q. eduardii infusion intake on inflammatory and oncogenic biomarkers in animals induced to have colorectal cancer with DMH. We also investigated its influence on the microbiota, establishing the main microbial metabolites in the intestinal content of the experimental animals. The microbial metabolites associated with greater anti-inflammatory and anticarcinogenic activity were 3́-hydroxyphenylacetic acid (3HPA) and €-3-(3,4,5-trimethoxyphenyl) prop-2-enoic acid (TMCA). Finally, the intake of the Q. eduardii infusion significantly increased the abundance of the Erysipelotrichaceae and Lachnospiraceae families, that seems to have a great influence on the antitumor responses detected in the study.post-print4648 K
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