990 resultados para 1792


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The collection contains items relating to individual members of the family as well as the Seixas family in general. Included are papers of the following persons: Isaac Mendes Seixas (1708/9-1780/1), a copy of A voyage to Hudson's--Bay, by Henry Ellis, inscribed with his name on the title page, along with additional inscriptions on the end papers (1748); and a daily prayer book printed in Amsterdam (title page missing), with an inscription on the first page indicating that the book was owned by Seixas in 1758/9, and subsequently by his grandson, Theodore J. Seixas, in 1816/17.

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Contains business correspondence, accounts and documents relating to Jacob Franks of New York, his two sons, Moses and David, a nephew, Isaac, and a John Franks of Halifax, possibly a member of the family.

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Engl. summary: Improving the efficiency of sewage lagoons

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C20H35N3O6 (Boc-Aib-DL-Pip-Aib-OMe, Boc = tert-butyloxycarbonyl, Aib = alpha-aminoisobutyric acid, Pip = pipecolic acid, OMe = methoxy), M(r) = 413.5, monoclinic, P2(1)/c, a = 18.055 (3), b = 15.048 (3), c = 17.173 (3) angstrom, beta = 91.7 (1)-degrees, V = 4663.8 (9) angstrom3, Z = 8, D(m) = 1.16, D(x) = 1.178 Mg m-3, lambda(Mo Kalpha) = 0.71069 angstrom, mu = 0.081 mm-1, F(000) = 1792, T = 297 K. The final R value for 4925 [I greater-than-or-equal-to 3sigma(I)] reflections is 0.065 (wR = 0.067). The peptide backbone of the two independent molecules in the asymmetric unit is folded at the -Aib-Pip- sequence to form a type-I (I') beta-bend stabilized by a 1 <-- 4 intramolecular N-H...O=C hydrogen bond between the Aib(3) peptide N-H and Boc urethane C=O groups.

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Beginning with the ‘frog-leg experiment’ by Galvani (1786), followed by the demonstrations of Volta pile by Volta (1792) and lead-acid accumulator by Plante´ (1859), several battery chemistries have been developed and realized commercially. The development of lithium-ion rechargeable battery in the early 1990s is a breakthrough in the science and technology of batteries. Owing to its high energy density and high operating voltage, the Li-ion battery has become the battery of choice for various portable applications such as note-book computers, cellular telephones, camcorders, etc. Huge efforts are underway in succeeding the development of large size batteries for electric vehicle applications. The origin of lithium-ion battery lies in the discovery that Li+-ions can reversibly be intercalated into/de-intercalated from the Van der Walls gap between graphene sheets of carbon materials at a potential close to the Li/Li+ electrode. By employing carbon as the negative electrode material in rechargeable lithium-ion batteries, the problems associated with metallic lithium in rechargeable lithium batteries have been mitigated. Complimentary investigations on intercalation compounds based on transition metals have resulted in establishing LiCoO2 as the promising cathode material. By employing carbon and LiCoO2, respectively, as the negative and positive electrodes in a non-aqueous lithium-salt electrolyte,a Li-ion cell with a voltage value of about 3.5 V has resulted.Subsequent to commercialization of Li-ion batteries, a number of research activities concerning various aspects of the battery components began in several laboratories across the globe. Regarding the positive electrode materials, research priorities have been to develop different kinds of active materials concerning various aspects such as safety, high capacity, low cost, high stability with long cycle-life, environmental compatibility,understanding relationships between crystallographic and electrochemical properties. The present review discusses the published literature on different positive electrode materials of Li-ion batteries, with a focus on the effect of particle size on electrochemical performance.

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Three adhesion contact models, JKR (Johnson-Kendall-Roberts), DMT (Derjaguin-Muller-Toporov) and MD (Maugis-Dugdale) are compared with the Hertz model in dealing with the nano-contact problems. It has been shown that the dimensionless load parameter, $\bar{P}=P/(\pi\Delta\gamma R)$, and the transition parameter, $\Lambda$, have significant influences on the contact stiffness (contact area) at micro/nano-scale and should not be ignored in shallow nanoindentation.

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El repollo Brassica oleracea (L.), es la hortaliza de mayor consumo en estado fresco o procesado, seguido del tomate. Los problemas fitosanitarios en el cultivo de repollo han sido manejados tradicionalmente con el uso de insecticidas químicos, sin embargo esta alternativa ha provocado graves problemas al medio ambiente, al hombre, a la fauna benéfica existentes en los campos y por último resistencia de las plagas hacia los insecticidas químicos (Vareta 1987). Plutella xylostella (L.) es la plaga principal del cultivo de repollo, provocando su mayor daño en la parte comerciable (cabeza del repollo), causa pérdidas económicas al incrementar los costos de producción. El objetivo de este trabajo fue evaluar otras alternativas de manejo de la plaga Plutella xylostella (L.) utilizando, el insecticida botánico (Nim 20), biológico (Dipel), Nim 20 + Dipel y un tratamiento químico (Evisect). Los resultados de la investigación reflejaron que la incidencia de P. xylostella en el tratamiento biológico (Dipel) mostró niveles poblacionales superiores al resto de los tratamientos evaluados. Sin embargo el tratamiento Nim 20 + Dipel, mostró los niveles poblacionales inferiores al resto de los tratamientos. El mayor porcentaje promedio de parasitismo se registró en el tratamiento Nim 20 con un 35.85%, seguido por el tratamiento Nim 20 + Dipel con un porcentaje promedio de parasitismo de 31.52%. Según el análisis de varianza realizado a las poblaciones de los arácnidos en cada tratamiento no se encontró diferencias significativas. Por otra parte, el análisis de correlación realizado a las poblaciones de P. xylostella y a su parasitoide D. insulare se encontró que el tratamiento Evisect y el tratamiento Dipel resultaron más correlacionados, lo contrario sucedió en el tratamiento Nim 20 y el tratamiento Nim 20 + Dipel, los cuales resultaron menos correlacionados. Según el análisis económico de este estudio, el tratamiento Nim 20 resultó ser la alternativa más prometedor para el manejo de P. xylostella en el cultivo de repollo por mostrar bajo costo de producción y alto ingreso económico bajo las condiciones del productor.

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Resumen: Este artículo se aboca a un análisis comparativo de tres óperas basadas en el mito de Cenicienta, a partir de las versiones literarias canónicas de Basile, Perrault y Grimm: La Cenerentola de Rossini-Ferretti (1817), Cendrillon de Massenet-Cain (1899), y ¡Cenicientaaa...! de Lambertini (2008). Consideramos aspectos míticos del relato, como el combate cosmogónico, la unión hierogámica, la rivalidad fraterna y el complejo edípico, y estudiamos su vigencia y sus mutaciones a través de las sucesivas estéticas que corresponden a las tres óperas señaladas: iluminismo, romanticismo, posmodernidad.

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Plant surface areas were measured from samples of two common submersed aquatics with widely diverging morphologies: Eurasian watermilfoil ( Myriophyllum spicatum L.) and water stargrass ( Heteranthera dubia (Jacq.) MacM.). Measures for the highly dissected leaves of Eurasian watermilfoil involved development of a regression equation relating leaf length to direct measures of a subsample of leaf parts. Measures for the simple leaves of the stargrass were sums of measured triangles. Stem surfaces for both species were calculated as measured cylinders. Though the means of the stem length and leaf length were larger for stargrass samples, their mean surface area was 95 cm 2 which was less than the 108 cm 2 recorded for Eurasian watermilfoil samples. Relating surface area to dry weight for the stargrass was straightforward, with 1 mg of dry weight yielding an average 0.678 cm 2 of surface area. Biomass measures for the water milfoil were confounded by the additional weight of epiphytic algae persisting on cleaned samples. The results suggest that a lesstime consuming method for surface area measures of plants with highly dissected leaves and a caveat for using biomass measures to estimate surface area in such plants.