432 research outputs found

    Urban solar photovoltaics potential: An inventory and modelling study applied to the San Fernando Valley region of Los Angeles

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    Procedures for analyzing the potential of solar photovoltaic collectors to meet energy requirements in a metropolitan region are described and a modeling effort is applied to the San Fernando Valley region of Los Angeles. The procedure involves a series of steps designed to produce maps and tabulations revealing the amount of rooftop area available for establishing solar collectors and the proportion of energy requirement that could be potentially supplied by solar photovoltaics within each of the 533 mainline feeder service areas in the study area. For the sixty five square mile study area, the results showed that, with half the available flat and south facing roofs used and assuming the availability of energy storage, 52.7 percent of the actual kWh energy requirements could have been met in 1978 using photovoltaic collectors. Hourly, daily, weekly, and monthly fluctuations in potential supply and actual loads and recommendations of avenues for further research are discussed. Some further potential applications of the modeling technique are suggested

    Polyvinylpyridine-supported palladium nanoparticles: An efficient catalyst for Suzuki–Miyaura coupling reactions

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    Palladium nanoparticles (Pd NPs) synthesized by the metal vapor synthesis technique were supported on poly(4-vinylpyridine) 2% cross-linked with divinylbenzene (Pd/PVPy). Transmission electron microscopy revealed the presence of small metal nanoparticles (dm = 2.9 nm) highly dispersed on the PVPy. The Pd/PVPy system showed high catalytic efficiency in Suzuki-Miyaura carbon–carbon coupling reactions of both non-activated and deactivated aromatic iodides and bromides with aryl boronic acids, carried out under an air atmosphere. The high turnover of the catalyst and the ability of the PVPy resin to retain active Pd species are highlighted. By comparing the catalytic performances of Pd/PVPy with those observed by using commercially available Pd-based supported catalysts, the reported system showed higher selectivity and lower Pd leaching

    Macro-habitat preferences by the African manatee and crocodiles – ecological and conservation implications

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    African manatees (<i>Trichechus senegalensis</i>) and crocodiles are threatened species in parts of their range. In West Africa, crocodiles may constitute the main predators for manatees apart from humans. Here, we explore the macro-habitat selection of manatees and two species of crocodiles (West African crocodiles <i>Crocodylus suchus</i> and dwarf crocodile <i>Osteolaemus tetraspis</i>) in the Niger Delta (Nigeria), testing the hypotheses that (i) manatees may avoid crocodiles in order to minimize risks of predation, and (ii) the two crocodile species do compete. The study was carried out between 1994 and 2010 with a suite of different field techniques. We observed that the main macro-habitat types were freshwater rivers and coastal lagoons for manatees, mangroves for West African crocodiles, and rivers and creeks for dwarf crocodiles, with (i) the three species differing significantly in terms of their macro-habitat type selection, and (ii) significant seasonal influence on habitat selection of each species. Null models for niche overlap showed a significantly lower overlap in macro-habitat type use between manatee and crocodiles, whereas the two crocodiles were relatively similar. Null model analyses did not indicate any competitive interactions between crocodiles. On the other hand, manatees avoided macro-habitats where crocodiles, and especially West African crocodiles, are abundant

    Total Synthesis of Asparenydiol by Two Sonogashira Cross-Coupling Reactions Promoted by Supported Pd and Cu Catalysts

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    Asparenydiol, which is an important natural compound with potential pharmacological activities, was synthesized through two Sonogashira cross-coupling reactions catalyzed by supported Pd and Cu catalysts and by a Mitsunobu etherification. The optimization of the Sonogashira couplings allowed the use of catalysts supported on different matrices with good results in terms of catalytic efficiency and yields

    Macro-habitat preferences by the African manatee and crocodiles – ecological and conservation implications

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    Abstract. African manatees (Trichechus senegalensis) and crocodiles are threatened species in parts of their range. In West Africa, crocodiles may constitute the main predators for manatees apart from humans. Here, we explore the macro-habitat selection of manatees and two species of crocodiles (West African crocodiles Crocodylus suchus and dwarf crocodile Osteolaemus tetraspis) in the Niger Delta (Nigeria), testing the hypotheses that (i) manatees may avoid crocodiles in order to minimize risks of predation, and (ii) the two crocodile species do compete. The study was carried out between 1994 and 2010 with a suite of different field techniques. We observed that the main macro-habitat types were freshwater rivers and coastal lagoons for manatees, mangroves for West African crocodiles, and rivers and creeks for dwarf crocodiles, with (i) the three species differing significantly in terms of their macro-habitat type selection, and (ii) significant seasonal influence on habitat selection of each species. Null models for niche overlap showed a significantly lower overlap in macro-habitat type use between manatee and crocodiles, whereas the two crocodiles were relatively similar. Null model analyses did not indicate any competitive interactions between crocodiles. On the other hand, manatees avoided macro-habitats where crocodiles, and especially West African crocodiles, are abundant

    La vita in una goccia d'acqua: spunti per un'azione didattico-educativa.

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    Il progetto \ue8 stato presentato dal Consiglio Direttivo della SIP (Societ\ue0 Itlaiana di Protistologia ONLUS). L\u2019obiettivo principale di questo progetto \ue8 quello di costituire ed organizzare un\u2019iniziativa didatticoformativapresso gli insegnanti di scienze della scuola secondaria di primo grado, come educatori della classe dei giovani in et\ue0 scolare, volta a sviluppare le cognizioni scientifico-applicative sull\u2019importanza dei microorganismi unicellulari eucariotici, comunemente definiti "protisti", in ambito sanitario e ambientale. Molto spesso dei protisti, i principali artefici del pi\uf9 grande salto evolutivo nella storia dei viventi, non esiste il bench\ue9 minimo accenno. La principale ragione di tale incompletezza sta nella non facile presentazione di tali organismi. I protisti, infatti, hanno dimensioni microscopiche e quindi non sono visibili ad occhio nudo. Eppure, questi organismi, oltre ad avere un elevata importanza evolutiva, sono indicatori di qualit\ue0 dell\u2019ambiente oltre ad essere di imponente interesse sanitario. I protisti di tipo parassitologico sono gli agenti infettanti di malattie molto gravi, quali la malaria, la toxoplasmosi e la leishmaniosi, tra le pi\uf9 note, e rivestono, oggi, grande importanza nei progetti d\u2019interesse prioritario per gli interventi istituzionali di sanit\ue0 pubblica in Italia e nel resto del mondo, ma di essi e delle loro infezioni ben poco sanno gli operatori e gli utenti della scuola secondaria dove, invece, il messaggio educazionale pu\uf2 essere molto efficiente anche in termini di prevenzione. Per tutto questo \ue8 molto importante promuovere la conoscenza di tale \u201cmondo sommerso\u201d nel quale esistono organismi sia da evitare in quanto patogeni (prevenzione primaria) che da promuovere in ambienti naturali (monitoraggio ambientale e controllo dell\u2019inquinamento). Il secondo obiettivo \ue8 quello di mettere al servizio di questa iniziativa le conoscenze scientifiche che vengono dalla ricerca, la pi\uf9 specializzata, come quella perseguita dai ricercatori che nel progetto svolgono le docenze. Contestualmente, il terzo obiettivo \ue8 quello di sopperire alla mancanza di informazioni sui protisti, rendendo evidente, attraverso l\u2019allestimento di una sala didattico-espositiva presso il Museo del Mare che ha sede nell\u2019Area Marina Protetta (AMP) Torre del Cerrano, l\u2019immagine di questo microcosmo, che svela i principali fenomeni che regolano la vita sulla Terra e che svolge un importante ruolo per la conservazione della biodiversit\ue0 sul nostro pianeta. Quest\u2019ultimo obiettivo \ue8 raggiunto anche dagli insegnanti e dai loro studenti, mettendo in uso le conoscenze ottenute nel corso del progetto, tramite l\u2019utilizzo della sala didattico-espositiva come un laboratorio di ricerca. In base a quanto sopra esposto possiamo dire che i risultati attesi da questo progetto sono: 1. Accrescimento delle cognizioni tecnico-scientifiche da parte degli insegnanti di scienze della scuola secondaria arruolati nel progetto nel settore della Protistologia, con particolare riguardo all\u2019importanza evolutiva e applicativa nel settore ambientale e sanitario dei protisti. 2. Ricaduta di queste cognizioni sugli studenti delle classi coinvolte, come risultato dell\u2019adempimento didattico dei suddetti insegnanti e rafforzamento delle stesse tramite l\u2019utilizzazione della sala didattico-espositiva come laboratorio applicativo di lavori di gruppo sul tema dei protisti e del loro coinvolgimento nella qualit\ue0 dell\u2019ambiente e della salute. 3. Ottenimento della collaborazione tra ricerca universitaria, scuola e aree marine protette in maniera sinergica

    Identification and synthesis of new sex-specific components of olive fruit fly (Bactrocera oleae) female rectal gland, through original Negishi reactions on supported catalysts

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    In the present study, eleven new sex-specific components extracted from female rectal gland of olive fruit flies were synthesized and identified. The quantitative determination of those components by GC and GC/EI-MS, at different moments of the insect life span, highlighted the growing trend of their secretion. While for the synthesis of saturated esters, conventional transesterification methods could be adopted, for the synthesis of unsaturated components, a Negishi cross-coupling between organozinc halides and (Z)-1-bromo-1-alkenes was developed. To the extent of our knowledge, this reaction represents the first example of supported-catalyst promoted Negishi coupling, between an alkylzinc reagent and an alkenyl halide

    Spigelian hernia: a case report and review of the literature

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    Spigelian hernia is a rare abdominal hernia that occurs through Spigelian aponeurosis. The Authors present a case of Spigelian hernia associated with narrowing of sigmoid colon and diverticular pathology.They also described historical background, surgical anatomy and etiopathogenesis of this hernia. By a remarkable revision of literature, they sum up epidemiology and clinical features of Spigelian hernia. Furthermore, they discuss diagnostic and therapeutic principles

    Retrospective assessment of inguinal hernia repair in elderly outpatients

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    Background In the last ten years Day Surgery has significantly evolved, due to improvements in surgery and anaesthesia, and the need of reducing long term admission costs [1]. However, is Day Surgery suitable for elderly patients? The aim of this paper is to assess the risk of over 70 year-old outpatients who underwent inguinal hernia repair, and suggest an adequate preoperative pathway
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