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  • 1
    Publication Date: 2013-11-01
    Description: The biogeochemical cycles of carbon (C), nitrogen (N) and phosphorus (P) are interlinked by primary production, respiration and decomposition in terrestrial ecosystems. It has been suggested that the C, N and P cycles could become uncoupled under rapid climate change because of the different degrees of control exerted on the supply of these elements by biological and geochemical processes. Climatic controls on biogeochemical cycles are particularly relevant in arid, semi-arid and dry sub-humid ecosystems (drylands) because their biological activity is mainly driven by water availability. The increase in aridity predicted for the twenty-first century in many drylands worldwide may therefore threaten the balance between these cycles, differentially affecting the availability of essential nutrients. Here we evaluate how aridity affects the balance between C, N and P in soils collected from 224 dryland sites from all continents except Antarctica. We find a negative effect of aridity on the concentration of soil organic C and total N, but a positive effect on the concentration of inorganic P. Aridity is negatively related to plant cover, which may favour the dominance of physical processes such as rock weathering, a major source of P to ecosystems, over biological processes that provide more C and N, such as litter decomposition. Our findings suggest that any predicted increase in aridity with climate change will probably reduce the concentrations of N and C in global drylands, but increase that of P. These changes would uncouple the C, N and P cycles in drylands and could negatively affect the provision of key services provided by these ecosystems.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Delgado-Baquerizo, Manuel -- Maestre, Fernando T -- Gallardo, Antonio -- Bowker, Matthew A -- Wallenstein, Matthew D -- Quero, Jose Luis -- Ochoa, Victoria -- Gozalo, Beatriz -- Garcia-Gomez, Miguel -- Soliveres, Santiago -- Garcia-Palacios, Pablo -- Berdugo, Miguel -- Valencia, Enrique -- Escolar, Cristina -- Arredondo, Tulio -- Barraza-Zepeda, Claudia -- Bran, Donaldo -- Carreira, Jose Antonio -- Chaieb, Mohamed -- Conceicao, Abel A -- Derak, Mchich -- Eldridge, David J -- Escudero, Adrian -- Espinosa, Carlos I -- Gaitan, Juan -- Gatica, M Gabriel -- Gomez-Gonzalez, Susana -- Guzman, Elizabeth -- Gutierrez, Julio R -- Florentino, Adriana -- Hepper, Estela -- Hernandez, Rosa M -- Huber-Sannwald, Elisabeth -- Jankju, Mohammad -- Liu, Jushan -- Mau, Rebecca L -- Miriti, Maria -- Monerris, Jorge -- Naseri, Kamal -- Noumi, Zouhaier -- Polo, Vicente -- Prina, Anibal -- Pucheta, Eduardo -- Ramirez, Elizabeth -- Ramirez-Collantes, David A -- Romao, Roberto -- Tighe, Matthew -- Torres, Duilio -- Torres-Diaz, Cristian -- Ungar, Eugene D -- Val, James -- Wamiti, Wanyoike -- Wang, Deli -- Zaady, Eli -- England -- Nature. 2013 Oct 31;502(7473):672-6. doi: 10.1038/nature12670.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉1] Departamento de Sistemas Fisicos, Quimicos y Naturales, Universidad Pablo de Olavide, Carretera de Utrera, kilometro 1, 41013 Sevilla, Spain [2] Area de Biodiversidad y Conservacion, Departamento de Biologia y Geologia, Escuela Superior de Ciencias Experimentales y Tecnologia, Universidad Rey Juan Carlos, Calle Tulipan Sin Numero, 28933 Mostoles, Spain.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/24172979" target="_blank"〉PubMed〈/a〉
    Keywords: Aluminum Silicates/analysis ; Biomass ; Carbon/analysis/metabolism ; Carbon Cycle ; Climate Change ; *Desert Climate ; *Desiccation ; *Ecosystem ; *Geography ; Models, Theoretical ; Nitrogen/analysis/metabolism ; Nitrogen Cycle ; Phosphoric Monoester Hydrolases/analysis/metabolism ; Phosphorus/analysis/metabolism ; Plants/metabolism ; Soil/*chemistry
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 2
    Publication Date: 2022-10-27
    Description: Notable trabajo cartográfico de la Marina de Guerra del Perú - La costa del Perú: Evaluando los efectos del Tsunami del 01 de abril del 2014 - Perfilador de fondo marino: tecnología de punta para exploración geológica - En el Puerto Salaverry: eficaz estudio de la tasa de transporte eólico - Modelamiento numérico de olas en la bahía del Callao, a partir de información en aguas profundas - Evaluando la variabilidad del perfil costero en la Ensenada MacKellar - Oportuna implementación del software CARIS Bath DataBASE - Hacia una moderna aplicación de CARIS HIPS and SIPS. Taller de procesamiento de datos Multihaz - Usos del software Caris HPD-Source Editor en la cartografía náutica: Cumpliendo los requerimientos de las normas de calidad ISO 9001 - Producción de cartas náuticas utilizando extensiones del software Paper Chart Editor - Sistema de Información Geográfica, herramienta que permite monitorear la actividad sísmica - Eficiente manejo y administración de Bases de Datos Espaciales - Sistema de Realidad Aumentada: Amplias ventajas para el trabajo de campo - Energía renovable undimotriz al 2025: Hacia una prospectiva para el desarrollo - Para las boyas de señalización náutica: sincronismo y sistemas redundantes - Presencia en la reuniones del Servicio Mundial de Avisos a los Navegantes
    Description: Published
    Description: Refereed
    Keywords: Cartografía ; Cartas náuticas ; Mareas ; Señalización náutica ; Modelamiento numérico ; Sedimentos marinos ; ASFA_2015::O::Oceanography ; ASFA_2015::H::Hydrography ; ASFA_2015::C::Climatic changes
    Repository Name: AquaDocs
    Type: Book/Monograph/Conference Proceedings
    Format: 80pp.
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  • 3
    Publication Date: 2022-09-15
    Description: Contenido: Eficaz gestión con proyección hacia un nuevo horizonte - Areas marinas protegidas creación de la Reserva Nacional Dorsal de Nasca, la primera área marina protegida del Perú – Retos y perspectivas en la investigación del fondo marino de las 200 millas náuticas del Mar de Grau: Una mirada hacia la planificación espacial marina y economía azul Análisis de la problemática de erosión en la playa La Herradura - Nuevas tecnologías para monitoreo oceanográfico y meteorológico en el litoral peruano -Impresión de cartas náuticas del sistema offset convencional a la impresión digital en alta y baja demanda - Cartas náuticas siguen tendencias en tecnologías digitales - Archivo cartográfico histórico logró gran transformación - Especificación de producto para cartas náuticas electrónicas "S-101" - Especialistas en geocodificación apoyan al grupo de trabajo "Te Cuido Perú" y sus operaciones TAYTA - Imágenes del satélite PeruSat-1 y su aplicación en la Cartografía Náutica - En isla Hormigas de Afuera: multidisciplinario equipo refuerza construcción de luminoso faro y estación oceanográfica al servicio del país - Faro "Morro Carretas" refuerza su potencia en el puerto de Salaverry - Optimización de las ayudas a la navegación en la costa peruana - Aplicación del sistema eólico en la estación isla Lobos de Afuera - Determinación de la línea de más alta marea en Tumbes y Piura - BAP Stiglich una gran contribución al desarrollo de la región amazónica - La Organización Hidrográfica Internacional ejecuta eficaz trabajo - El Perú en la Antártida: Hidrógrafos peruanos haciendo patria en el continente polar - Atlas Islas e Islotes del Mar Peruano. publicación que fortalece el conocimiento del patrimonio marítimo nacional - El "Manual del Navegante" - Los derroteros, una larga historia - Faro La Jument registra las fotografías más famosas del mundo.
    Description: Published
    Description: Refereed
    Keywords: Mareas ; Alerta de tsunamis ; Ayudas a la navegación ; ASFA_2015::O::Oceanography ; ASFA_2015::H::Hydrography ; ASFA_2015::M::Meteorology
    Repository Name: AquaDocs
    Type: Book/Monograph/Conference Proceedings
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  • 4
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The formation of a charge-transfer complex (CTC) between maleic anhydride and tetrahydrofuran both in bulk and in chloroform solution is proved by electronic absorption spectroscopy, and its association constant at 35°C is determined by this technique and by 1H NMR. The effect of irradiation with monochromatic 350 nm light upon the fluorescence spectrum of the CTC excited with this same radiation is studied. Significant changes are noted in the bulk system, but the changes are much smaller in the presence of methyl methacrylate which is simultaneously polymerized. The effect of oxygen on the polymerization is discussed.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Hydrosilylation reactions of 1-allyloxy-3-phenoxy-2-propanol (3) as model compound were carried out with α-dimethylsilyl-ω-hydrooligosiloxane (7; M̄n = 1200) in the presence of hexachloroplatinic acid. It was found that under stoichiometric conditions only 75--80% of the allyl groups were hydrosilylated, due to some isomerization of the allyl groups into vinyl groups, which do not undergo hydrosilylation. This isomerization could be shown to be sensitive to the type of the allyloxy structure. Thus, for example, allyloxybenzene does not undergo isomerization.
    Additional Material: 5 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 190 (1989), S. 2789-2803 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: All the side-reactions of a hydrosilylating model system (1-allyloxy-3-phenoxy-2-propanol/. . .-Si(CH3)2H in the presence of hexachloroplatinic acid (CPA); R = [CPA]/[SiH] 〉 10-4) are identified by 13C and 1H NMR. In such conditions the vinyl ether isomers and the residual silanes, formed when R 〈 10-4, are changed into several new species. The most important side-reaction consists in a silane-alcohol condensation (secondary alcohol of the model and, to a much lower extent, tertiary alcohol(tert-butyl alcohol) used as solvent of CPA), which leads to silyloxygrafted moieities. Hydrogen formed in this condensation can partially saturate the vinyl ether isomers the remaining fraction of which is cyclized into a 2-ethyl-1,3-dioxolane derivative. All the side-reactions observed in the case of the model system take place when α,β-diallyloligosulfones are polycondensated with α-dimethylsilyl-ω-hydrooligosiloxanes.
    Additional Material: 9 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 1691-1703 
    ISSN: 0887-624X
    Keywords: 3-alkoxy-5,7-diiodo-6-fluorones ; visible photoinitiators ; acrylate photopolymerization ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Several 3-alkoxy-5, 7-diiodo-6-fluorones (λmax ≈ 470 nm) have been synthesized and evaluated as initiators for photopolymerization triggered with the 515.5 nm line of an Ar+ laser. 2-Acyl- and 2-alkyl-4,5,7-triiodo-3-hydroxy-6-fluorones were also tested at 515.5 nm. 9-Cyano-2-Acyl- and 9-cyano-2-alkyl-4,5,7-triiodo-3-hydroxy-6-fluorones were studied and could be excited with the 632 nm line of a He-Ne laser. Dyes with long linear carbon chain alkoxy groups at C-6 showed larger molar extinction coefficients and formed polymers with better mechanical properties than did compounds with shorter carbon chains, or did the corresponding C-6 phenols. The optimum side chain length of the C-6 ether alkyl group is between 4-7 carbon atoms. With longer carbon chain alkoxy groups at C-8, e.g., octyl, the mechanical properties of the formed polymers are inferior to systems formed with the butyl isomer as photoinitiator. In the case of alkoxy groups with branched alkyl groups (e.g., 2-ethylbutyl), the relationship between dye structure and the properties of the polymers formed is less straightforward. Though the dyes react from their triplet state, the fluorescence quantum yields of the dyes and the performance of the dyes as photoinitiators appear directly related. © 1995 John Wiley & Sons, Inc.
    Additional Material: 1 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 28 (1990), S. 1579-1592 
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Differential scanning calorimetry (DSC) has been utilized in several studies on polymerization kinetics, at different heating rates. However, there are several factors affecting the precision of kinetic parameters. In this work, the activation energy of urethane-bond formation between 2,6-tolylene diisocyanate and diethylene glycol is reported, the latter being in excess in order to minimize problems such as thermal transitions and incomplete reaction in the final step. The DSC technique was applied at different heating rates. Both the equal conversion and equal conversion rate options of the method are discussed. The latter appears to be a more adequate option for the system studied here. The results obtained show a good agreement with the model used.
    Additional Material: 8 Ill.
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  • 9
    ISSN: 0935-9648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Additional Material: 1 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 31 (1993), S. 959-970 
    ISSN: 0887-6266
    Keywords: laser-induced processes in conducting polymer precursors ; interaction of dyes with polyelectrolytes ; lithography ; microelectronics ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The elimination reaction of polyelectrolyte films of poly(phenylene vinylene) precursor polymers into the fully conjugated chain was induced by irradiation with an Ar+ laser emitting at 514.5 nm. The experiments were conducted using as cast precursor polyelec-trolyte films of both the unsubstituted poly(phenylene vinylene), H-PPV, and its 2,5-dimethoxyphenylene derivative, DMEO-PPV. Precursor polymer films impregnated with an azosulfonic dye, which had a strong absorption at the laser emission wavelength, were also irradiated. The elimination reaction was followed by comparing the elemental analysis and the infrared and visibleultraviolet spectra of the irradiated and nonirradiated areas. With the unsubstituted PPV film no elimination was detected even at power fluence levels up to approximately 350 W/cm-2, but elimination and conversion to the conjugated polymer could be observed at 10 W/cm-2 when the dye was present. For DMEO-PPV the elimination reaction occurred with or without dye impregnation, and similar marking threshold values were measured in both cases. The molecular mechanism used to explain such observations and the possible application in the area of microelectronics are also discussed. © 1993 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
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