Mostrando recursos 1 - 20 de 1.132

  1. Identification of asymptomatic plants infected with Citrus tristeza virus from a time series of leaf spectral characteristics

    Afonso, Andreia; Guerra, Rui; Cavaco, Ana M.; Pinto, Patrícia; Andrade, André; Duarte, Amílcar; Power, Deborah; Marques, Natália T.
    Citrus tristeza virus (CTV) affects citrus crops with differing severity, depending on the viral strain, the citrus cultivar and the scion/rootstock combinations. In this study we address the problem of identifying asymptomatic infected plants using reflectance spectra of the leaves in the visible/near infrared region. Sixteen young citrus plants (8 Citrus x clementina hort. ex Tanaka ‘Fina’ and 8 Citrus sinensis (L.) Osbeck ‘Valencia Late’) were split into control and T318A isolate infected groups. Measurements of reflectance in the 400-1100 nm range, in two leaves per plant, were performed monthly over 6 months and the presence of the virus was...

  2. A situação atual da citricultura na Flórida

    Duarte, Amílcar
    No passado dia 25 de maio, no auditório da Caixa de Crédito Agrícola, em Algoz, teve lugar uma palestra com o título “A situação atual da citricultura na Flórida”, inserida no ciclo de seminários associado ao mestrado em Hortofruticultura da Universidade do Algarve. A palestra foi proferida por Thomas Stopyra, um prestigiado agrónomo americano que trabalha na empresa The Packers of Indian River, Ltd., especializada na produção de toranja para consumo em fresco. A palestra teve como tema central os problemas fitossanitários que têm afetado a citricultura da Flórida, nomeadamente, o cancro cítrico e, mais recentemente, o Huanglongbing (HLB ou greening). No caso do cancro cítrico, houve uma tentativa inicial de eliminação de todas as...

  3. Cationic polyene phospholipids as DNA carriers for ocular gene therapy

    Machado, Susana; Calado, Sofia; Bitoque, Diogo; Oliveira, Ana Vanessa; Øpstad, Christer L.; Zeeshan, Muhammad; Sliwka, Hans-Richard; Partali, Vassilia; Pungente, Michael D.; Silva, Gabriela
    Recent success in the treatment of congenital blindness demonstrates the potential of ocular gene therapy as a therapeutic approach. The eye is a good target due to its small size, minimal diffusion of therapeutic agent to the systemic circulation, and low immune and inflammatory responses. Currently, most approaches are based on viral vectors, but efforts continue towards the synthesis and evaluation of new nonviral carriers to improve nucleic acid delivery. Our objective is to evaluate the efficiency of novel cationic retinoic and carotenoic glycol phospholipids, designated C20-18, C20-20, and C30-20, to deliver DNA to human retinal pigmented epithelium (RPE) cells....

  4. Factors affecting rind pitting in the mandarin hybrids "fortune" and "nova". The influence of exogenous growth regulators

    Duarte, Amílcar; Guardiola, J. L.
    The commercialization of the mandarin hybrids "Fortune" and "Nova" is hindered by the development of cold-induced pitting in the fruit rind which may develop either in the orchard or during storage and transport. In the late cropping cultivar "Fortune", the pitting develops on tree during the winter months and affects mainly the exposed fruit from the north-west quadrant of the tree. The induction of symptoms under uniform conditions in the cold-room reveals differences in the susceptibility to chilling injury among the fruits and the fruit sides. The green fruit is not susceptible. Susceptibility develops as pigmentation progresses, and it is higher...

  5. Efficiency of RAFT-synthesized PDMAEMA in gene transfer to the retina

    Bitoque, Diogo B.; Simão, Sónia; Oliveira, Ana V.; Machado, Susana; Duran, Margarita R.; Lopes, Eduardo; Costa, Ana M. Rosa da; Silva, Gabriela
    Gene therapy has long been heralded as the new hope to evolve from symptomatic care of genetic pathologies to a full cure. Recent successes in using gene therapy for treating several ocular and haematopoietic pathologies have shown the great potential of this approach that, in the early days, relied on the use of viral vectors, which were considered by many to be undesirable for human treatment. Therefore, there is considerable interest and effort in developing non-viral vectors, with efficiency close to that of viral vectors. The aim of this study was to develop suitable non-viral carriers for gene therapy to...

  6. Analyzing spatial patterns linked to the ecology of herbivores and their natural enemies in the soil

    Campos-Herrera, Raquel; Ali, J. G.; Diaz, B. M.; Duncan, L. W.
    Modern agricultural systems can benefit from the application of concepts and models from applied ecology. When understood, multitrophic interactions among plants, pests, diseases and their natural enemies can be exploited to increase crop production and reduce undesirable environmental impacts. Although the understanding of subterranean ecology is rudimentary compared to the perspective aboveground, technologies today vastly reduce traditional obstacles to studying cryptic communities. Here we emphasize advantages to integrating as much as possible the use of these methods in order to leverage the information gained from studying communities of soil organisms. PCR-based approaches to identify and quantify species (real time qPCR...

  7. The abundance, diversity, and metabolic footprint of soil nematodes is highest in high elevation alpine grasslands

    Kergunteuil, Alan; Campos-Herrera, Raquel; Sánchez-Moreno, Sara; Vittoz, Pascal; Rasmann, Sergio

  8. Effects of cover crops on the overwintering success of entomopathogenic nematodes and their antagonists

    Jaffuel, Geoffrey; Blanco-Pérez, Rubén; Büchi, Lucie; Mäder, Paul; Fließbach, Andreas; Charles, Raphaël; Degen, Thomas; Turlings, Ted C.J.; Campos-Herrera, Raquel
    Conservation agriculture is arising as an alternative to conventional agriculture with the aim to have a reduced impact on the environment. This includes the use of cover crops to conserve soil quality by limiting soil erosion, adding organic matter, and enhancing soil nutrient content, as well as water availability, which are all factors that can greatly influence the presence of soil organisms. In the current study, we investigated whether winter cover crops can enhance the persistence of entomopathogenic nematodes (EPN) over the winter season. In a first trial we augmented EPN populations in plots without (bared) and with the cover crops, pea (Pisum sativum) or mustard...

  9. Efficacy of Electrolyzed Water to Inactivate Foodborne Pathogens on Fresh-Cut Apples

    Graça, A.; Nunes, C.; Quintas, C.; Abadias, M.; Usall, J.; Salazar, M.
    Chlorine is the most common disinfectant used in the fresh-cut industry but nowadays environmental and health risks have led to the need to find new sanitizers. Electrolyzed water (EW) appears to be a promising alternative. In this work, disinfection efficacy of acidic (AEW) and neutral (NEW) electrolyzed water in fresh-cut apple slices inoculated with Escherichia coli, Listeria innocua or Salmonella choleraesuis was studied. Apple slices were inoculated with a 10(7) cfu/ml suspension of pathogens and treated with the sanitizer EW solutions, with 100 or 50 ppm of free chlorine solutions and with distilled water. Population reduction was determined 30 min...

  10. Speleothem shape and natural remanent magnetization

    Ponte, J.; Font, E.; Veiga-Pires, C.; Hillaire-Marcel, C.
    Speleothems might be of interest for high-resolution reconstruction of the Earth’s magnetic field. However, little is known about the influence of speleothem morphologies on their Natural Remanent Magnetization (NRM).

  11. Paleomagnetism in speleothems: influence of calcite growth dip on the natural remanent magnetization

    Font, E.; Ponte, J.; Veiga-Pires, C.; Hillaire-Marcel, C.
    Recent studies recognized speleothems as excellent recorders of the Earth’s magnetic field. However, some questions remain about the origin of the natural remanent magnetization and about the influence of the speleothem shape on the recorded magnetic directions.

  12. Efficiency of triple emitter source (TES) for irrigation experiments of horticultural crops

    Beltrão, J.; Jesus, S. B.; Silva, V.; Sousa, P. B.; Carvalho, Isabel Saraiva de; Trindade, D.; Rodrigues, M. H.; Machado, A.
    Triple emitter source TES experimental irrigation was designed. Three trickle laterals were connected together in order to form a triple joint lateral. Two of them and their emitters are connected to two tanks of stock solutions. The third lateral contains only fresh water. The emitters of the two solution lines have different and varying discharges to obtain several mixings of the two stock solutions. The third line is necessary to obtain constant water application rates for each trickling point along the lateral. This method was tested for several experiments involving the study of the combined effects of salinity and fertilizers...

  13. Gas-phase dehydration of glycerol over hierarchical silicoaluminophosphate SAPO-40

    Fernandes, Auguste; Filipa Ribeiro, M.; Lourenço, J. P.
    Hierarchical silicoaluminophosphate SAPO-40 was synthetized using an organosilane acting as additional porogen agent. The structural, textural and acid properties of the new material were evaluated using XRD, 29Si and 27Al MAS NMR, SEM, N2 adsorption, pyridine adsorption followed by IR spectroscopy and thermal analyses. The evaluation of the catalytic performance in the dehydration of glycerol has evidenced a high activity and a very low deactivation rate. When compared with the conventional SAPO-40, this catalyst shows higher acrolein selectivity and a significantly longer catalytic lifetime.

  14. UHMWPE/HDPE in-reactor blends, prepared by in situ polymerization: synthetic aspects and characterization

    Ferreira, A. E.; Cerrada, M. L.; Pérez, E.; Lorenzo, V.; Vallés, E.; Ressia, J.; Cramail, H.; Lourenco, J. P.; Ribeiro, M. R.
    This work covers the synthesis and characterization of in-reactor Ultra-High Molecular Weight Polyethylene/ High Density Polyethylene, UHMWPE/HDPE, blends by in situ polymerization in a single reactor, through dual catalyst immobilization. These blends are synthesized combining two different catalysts (one for each targeted molar mass) co-immobilized in mesoporous Santa Barbara Amorphous, SBA-15, particles. First, the ethylene polymerization behavior is investigated, under different polymerization conditions. Then, studies on the thermal, mechanical and rheological characteristics of the produced in-reactor blends are presented and their performance is compared and discussed in a comprehensive way. Moreover, the effect of different filler contents on the properties exhibited by the resulting materials is...

  15. Coenzyme Q10 partially restores pathological alterations in a macrophage model of Gaucher disease

    Mata, Mario de la; Cotán, David; Oropesa-Ávila, Manuel; Villanueva-Paz, Marina; Lavera, Isabel de; Álvarez-Córdoba, Mónica; Luzón-Hidalgo, Raquel; Suárez-Rivero, Juan M.; Tiscornia, Gustavo; Sánchez-Alcázar, José A.
    Background Gaucher disease (GD) is caused by mutations in the GBA1 gene which encodes lysosomal β-glucocerebrosidase (GCase). In GD, partial or complete loss of GCase activity causes the accumulation of the glycolipids glucosylceramide (GlcCer) and glucosylsphingosine in the lysosomes of macrophages. In this manuscript, we investigated the effects of glycolipids accumulation on lysosomal and mitochondrial function, inflammasome activation and efferocytosis capacity in a THP-1 macrophage model of Gaucher disease. In addition, the beneficial effects of coenzyme Q10 (CoQ) supplementation on cellular alterations were evaluated. Chemically-induced Gaucher macrophages were developed by differentiateing THP-1 monocytes to macrophages by treatment with phorbol 12-myristate...

  16. O "menu químico" das plantas: uma abordagem ao ensino da química no ensino secundário

    Rio, Carolina; Mateus, Maria da Conceição D. A.
    O papel da interdisciplinaridade na sedimentação de conceitos básicos e estruturantes para o desenvolvimento da aprendizagem em química pode ser implementado através de pequenos projetos que implicam a realização de procedimentos laboratoriais repetitivos conducentes ao desenvolvimento da memória de longo prazo, bem como criativos e de interligação de conceitos. O projeto aqui apresentado é uma proposta de trabalho para implementação nas escolas de ensino secundário, em atividades paralelas à sala de aula. Tendo como objeto de estudo os sistemas biológicos, é proposta a monitorização de diversos parâmetros químicos, necessários ao desenvolvimento de espécies hortícolas selecionadas, com o objetivo de dinamizar...

  17. Recovery of gold(0) nanoparticles from aqueous solutions using effluents from a bioremediation process

    Assunção, Ana; Vieira, Bernardete; Lourenço, J. P.; Costa, Maria Clara
    The use of biological processes with the aim of the recovery of gold from low-concentration solutions derived from leaching of secondary sources is gaining increasing importance owing to the scarcity of the primary resources and the economic and environmental advantages usually presented by these methods. Thus, the addition in batch and continuous processes of different solutions containing biogenic sulphide, which was generated by the activity of sulphate-reducing bacteria (SRB), to gold(III) solutions was investigated for that purpose. In the batch experiments, AuS nanoparticles with sizes of between 6 and 14 nm were obtained (corresponding to 100% removal of Au(III) from solution)...

  18. Impact of biohybrid magnetite nanoparticles and moroccan propolis on adherence of methicillin resistant strains of staphylococcus aureus

    El-Guendouz, Soukaina; Aazza, Smail; Lyoussi, Badiaa; Bankova, Vassya; Lourenço, J. P.; Costa, Ana; Mariano, José; Miguel, Maria; Faleiro, Maria
    Biofilm bacteria are more resistant to antibiotics than planktonic cells. Propolis possesses antimicrobial activity. Generally, nanoparticles containing heavy metals possess antimicrobial and antibiofilm properties. In this study, the ability of adherence of Methicillin Resistant Strains of Staphylococcus aureus (MRSA) to catheters treated with magnetite nanoparticles (MNPs), produced by three methods and functionalized with oleic acid and a hydro-alcoholic extract of propolis from Morocco, was evaluated. The chemical composition of propolis was established by gas chromatography mass spectrometry (GC-MS), and the fabricated nanostructures characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Mossbauer spectroscopy and Fourrier transform infrared spectroscopy (FTIR). The...

  19. Hafnocene catalyst for polyethylene and its nanocomposites with SBA-15 by in situ polymerization: immobilization approaches, catalytic behavior and properties evaluation

    Ferreira, Ana E.; Cerrada, María L.; Pérez, Ernesto; Lorenzo, Vicente; Cramail, Henri; Lourenço, J. P.; Quijada, Raul; Ribeiro, M. Rosário
    A hafnocene catalyst combined with methylaluminoxane (MAO) has been used as catalytic complex for the preparation of a set of polyethylene homopolymers by in situ polymerization under homogenous conditions and of different nanocomposites with mesoporous SBA- 15 particles, the latter playing the dual role of catalyst support and nanofiller. Distinct immobilization approaches have been explored for obtainment of these nanocomposites. Moreover, catalytic features, thermal stability, melting and crystallization transitions and mechanical behavior have been evaluated for those materials.

  20. A new post-metallocene-ti catalyst with maltolate bidentade ligand: an investigation in heterogeneous polymerization reactions in different mesoporous supports

    Gheno, Grasiela; Basso, Nara Regina de Souza; Livotto, Paolo Roberto; Ribeiro, Maria Rosário; Lourenço, J. P.; Ferreira, Ana Elisa; Galland, Griselda Barrera
    A new titanium catalyst easily synthesized from ethylmaltol bidentate chelator ligand was studied in homogeneous and heterogeneous ethylene polymerization. The dichlorobis(3-hydroxy-2-ethyl-4-pyrone)titanium(IV) complex was characterized by 1H and 13C NMR (nuclear magnetic resonance), UV-Vis and elemental analysis. Theoretical study by density functional theory (DFT) showed that the complex chlorines exhibit cis configuration, which is important for the activity in olefin polymerization. The complex was supported by two methods, direct impregnation or methylaluminoxane (MAO) pre-treatment, in five mesoporous supports: MCM-41 (micro and nano), SBA-15 and also the corresponding modified Al species. All the catalytic systems were active in ethylene polymerization and the...

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