332 research outputs found
Molecular characterization of ‘Candidatus Phytoplasma mali’ strains in outbreaks of apple proliferation in north eastern Italy, Hungary, and Serbia
During 2005-2008 apple plants of different varieties showing proliferation symptoms were observed in diverse areas of north eastern Italy, Hungary and Serbia. PCR/RFLP analyses showed that all the samples were infected with ‘Candidatus Phytoplasma mali’. In the 16S plus spacer region two phytoplasma profiles (P-I and P-II) were distinguished. P-I profile was detected in reference strains AP, AT1, AT2, in samples from Serbia, and in the majority of samples from Trentino; the P-II profile was prevalent in samples from Veneto; both profiles were identified in samples from Hungary, in some cases together in single samples. The analyses of rpl22-s3 genes allow the identification, in all the samples showing a P-I profile, the presence of phytoplasmas belonging to rpX-A subgroup, while in the samples showing a P-II profile it was possible to distinguish the other three reported rpX subgroups. In the majority of samples from the Veneto region phytoplasmas belonging to rpX-D subgroup were identified, while rpX-B and rpX-C subgroups were identified only in a few samples from Trentino and Veneto regions, respectively. Further RFLP analyses on AP13/AP10 amplicons differentiate among strains belonging to the rpX-A subgroup: the samples from Serbia show AP profiles, while those from Trentino show AT-2 profiles. In the samples from Hungary the presence of AT1, AT2, and AP profiles was identified.Keywords: Apple, ‘Candidatus Phytoplasma mali’, phytoplasma strains, PCR/RFLP analyses, epidemiolog
Enhancing radiological monitoring of 137Cs in coastal environments using taxonomic signals in brown seaweeds
With the rapidly expanding global nuclear industry, more efficient and direct radiological monitoring approaches are needed to ensure the associated environmental health impacts and risk remain fully assessed and undertaken as robustly as possible. Conventionally, radiological monitoring in the environment consists of measuring a wide range of anthropogenically enhanced radionuclides present in selected environmental matrices and using generic transfer values for modelling and prediction that are not necessarily suitable in some situations. Previous studies have found links between taxonomy and radionuclide uptake in terrestrial plants and freshwater fish, but the marine context remains relatively unexplored. This preliminary study was aimed at investigating a similar relationship between brown seaweed, an important indicator in radiological monitoring programmes in the marine environment, and Caesium-137, an important radionuclide discharged to the marine environment. A linear mixed model was fitted using REsidual Maximum Likelihood (REML) to activity concentration data collected from literature published worldwide and other databases. The output from REML modelling was adjusted to the International Atomic Energy Agency (IAEA) quoted transfer value for all seaweed taxa in order to produce mean estimate transfer value for each species, which were then analysed by hierarchical ANalysis Of VAriance (ANOVA) based on the taxonomy of brown seaweeds. Transfer value was found to vary between taxa with increasing significance up the taxonomic hierarchy, suggesting a link to evolutionary history. This novel approach enables contextualisation of activity concentration measurements of important marine indicator species in relation to the wider community, allows prediction of unknown transfer values without the need to sample specific species and could, therefore, enhance radiological monitoring by providing accurate, taxon specific transfer values for use in dose assessments and models of radionuclide transfer in the environment
Ativação alcalina de cinzas volantes utilizando solução combinada de NaOH e Ca(OH)2
Este trabalho teve como objetivo avaliar o comportamento da resistência à compressão, ao longo do tempo, em amostras de argamassas à base de cinzas volantes álcali-ativadas. Como ativador alcalino foi utilizada uma solução combinada de NaOH e Ca(OH)2. A cura das amostras foi realizada de duas formas distintas. Na
primeira, as amostras foram mantidas em estufa à 70°C/12 hs e à temperatura constante de 22°C em sala climatizada até a idade de ensaio. Apesar de serem obtidas resistências da ordem de 20 MPa nas primeiras 24 hs, houve decréscimo da
resistência a partir da idade de 7 dias. Verificado esse comportamento, um segundo método de cura foi adotado. Para isso, o traço utilizado para o preparo de novas argamassas foi o mesmo adotado no método anterior. Porém, foram submetidas à temperatura constante de 70°C até a idade de ensaio. Nesse caso, as amostras
apresentaram decréscimo mais acentuado da resistência em menor espaço de tempo, quando comparado às amostras curadas no primeiro método. Como estudos complementares foram realizadas análises microestruturais da CV antes e depois da ativação, utilizando o MEV/EDS.The main objective of this work was to evaluate the development of the compressive strength, along time, in alkali-activated fly ash mortars. As alkaline activator a combined solution of NaOH and Ca(OH)2 was used. The cure of the samples was carried through two distinct forms. In the first one, samples were kept in oven at 70°C during the first 12 hours and at constant room temperature of 22°C afterwards, until the age of testing. Compressive strength of 20 MPa magnitude were achieved during the first 24 hours, however it started to decrease after the age of 7 days. Considering this behaviour, second method of curing was adopted for the same mixing proportions. However, mortar samples were kept in oven at 70°C until the age of testing. In this case, compressive strength results decreased more significantly and at earlier ages, when compared with the results of samples cured using the first method. As complementary to understand the decreasing in compressive strength, microstructural analyses of the fly ash, before and after the activation, have been
carried out, using the SEM/EDS
Cinzas volantes álcali-ativadas com solução combinada de NaOH e Ca(OH)2
Este trabalho teve como objetivo avaliar o comportamento da resistência à compressão, ao longo do tempo, em amostras de argamassas à base de cinzas volantes álcali-ativadas. Como ativador alcalino foi utilizada uma solução combinada de NaOH e Ca(OH)2. A cura das amostras foi realizada de duas formas distintas. Na primeira, as amostras foram mantidas em estufa à 70°C/12 h e à temperatura constante de 22°C em sala climatizada até a idade de ensaio. Apesar de serem obtidas resistências da ordem de 20 MPa nas primeiras 24 h, houve decréscimo da resistência a partir da idade de 7 dias. Verificado esse comportamento, um segundo método de cura foi adotado. Para isso, o traço utilizado para o preparo de novas argamassas foi o mesmo adotado no método anterior. Porém, foram submetidas à temperatura constante de 70°C até a idade de ensaio. Nesse caso, as amostras apresentaram decréscimo mais acentuado da resistência em menor espaço de tempo, quando comparado às amostras curadas no primeiro método. Como estudos complementares foram realizadas análises microestruturais da CV antes e depois da álcali-ativação, utilizando o MEV/EDS. Nas imagens microestruturais foi possível identificar três morfologias distintas nas pastas álcali-ativadas: uma composta de regiões com aspecto denso; outra apresentando partículas de cinzas volantes parcialmente solubilizadas; e outra mostrando a formação de produtos em forma de cristais aciculares. Porém, apenas o uso do MEV/EDS não foi suficiente para que se pudesse entender o mecanismo de reação deletéria provocada entre os ativadores alcalinos e a cinza volante. Portanto, trabalhos futuros deverão contemplar o uso de ferramentas auxiliares às adotadas nesse trabalho com o objetivo de esclarecer tal mecanismo deletério.The main objective of this work was to evaluate over time the development of the compressive strength of alkali-activated fly ash mortars. A combined solution of NaOH and Ca(OH)2 was used as alkaline activator. The curing of the samples was carried out in two distinct ways. In the first one, samples were kept at 70°C during the first 12 hours after mixing and at 22°C afterwards, until the age of testing. Although compressive strengths of about 20 MPa were achieved during the first 24 hours, the strength started to decrease after 7 days. Considering this behaviour, a second method of curing was adopted. The mix proportions were the same as before, however the mortar samples were kept in an oven at 70°C until the age of testing. In this case, the compressive strength values decreased more significantly and in a shorter period of time, as compared to the results obtained for samples cured using the first method. Complementary studies were performed in order to better understand the observed reduction in compressive strength. Microstructural analyses of the fly ash, before and after the alkali-activation, have been carried out using Scanning Electron Microscopy (SEM) and Energy-Dispersive Spectroscopy (EDS). It was possible to identify three different morphologies in the alkali-activated pastes: one composed by regions with dense aspect; other showing partially solubilised particles of fly ash; and a third showing the formation of products with a needle-like shape. The information provided by the SEM/EDS experiments was not enough to enable the complete understanding of the mechanism of the deleterious reaction that took place among the alkaline activators and the fly ash. Therefore, future studies should address this question by using additional analysis tools in order to clarify this deleterious mechanism
Bioavailability of phosphorus on highly weathered Oxisoils of the Brazilian Mid-West.
Soils from mid-west Brazil show strong phosphorus (P) fixation, which can reduce the efficiency of P fertilizers. Under this condition, soil competes with the plant for the applied P adsorbing it strongly in its mineral fraction. Nevertheless, in areas where crops are grown and fertilizers are added for many years, soil fertility status has increased over time, making these soils nonresponsive to P. The objective of this study was to evaluate how P availability changes with soil use. Forty soil samples were collected under different types of land use: native forest, pasture, no-tillage, and areas with periodic tillage. P fractionation was performed to determine the amount of P in the organic and inorganic fractions with high, medium, and low lability under each land use. Corn was cultivated in a greenhouse experiment to evaluate P uptake and values correlated with different P fractions. The results showed differences in the P fraction relations among different land uses. Cultivated areas (no tillage and periodic tillage) accumulated greater amounts of P in all fractions than pastures and the native forest. A higher proportion of labile organic P was observed under no tillage than under periodic tillage. NaHCO3 and NaOH 0.1 mol L-1were the most relevant P fractions for shoot P uptake. No tillage promoted the accumulation of available P fractions, suggesting that it is a good management strategy to ensure fertilizer use efficienc
Moving forward the Italian nursing education into the post-pandemic era: findings from a national qualitative research study
Background: During the CoronaVIrus-19 (COVID-19) pandemic, nursing education has been dramatically transformed and shaped according to the restrictions imposed by national rules. Restoring educational activities as delivered in the pre-pandemic era without making a critical evaluation of the transformations implemented, may sacrifice the extraordinary learning opportunity that this event has offered. The aim of this study was to identify a set of recommendations that can guide the Italian nursing education to move forward in the post-pandemic era. Methods: A qualitative descriptive design was undertaken in 2022–2023 and reported here according to the COnsolidated criteria for REporting Qualitative research guidelines. A network was established of nine Italian universities offering a bachelor’s degree in nursing for a total of 6135 students. A purposeful sample of 37 Faculty Members, 28 Clinical Nurse Educators and 65 Students/new graduates were involved. A data collection was conducted with a form including open-ended questions concerning which transformations in nursing education had been implemented during the pandemic, which of these should be maintained and valued, and what recommendations should address the transition of nursing education in the post-pandemic era. Results: Nine main recommendations embodying 18 specific recommendations have emerged, all transversally influenced by the role of the digital transformation, as a complementary and strengthening strategy for face-to-face teaching. The findings also suggest the need to rethink clinical rotations and their supervision models, to refocus the clinical learning aims, to pay attention towards the student community and its social needs, and to define a pandemic educational plan to be ready for unexpected, but possible, future events. Conclusions: A multidimensional set of recommendations emerged, shaping a strategic map of action, where the main message is the need to rethink the whole nursing education, where digitalization is embodied. Preparing and moving nursing education forward by following the emerged recommendations may promote common standards of education and create the basis on for how to deal with future pandemic/catastrophic events by making ready and prepared the educational systems
Characterization of Demolished Concretes with Three Different Strengths for Recycling as Coarse Aggregate
This paper presents a physical characterization for the recycling into new concretes of three comminuted concretes: C16/20 (“ordinary concrete”), C50/60 (“high strength concrete”), and C70/85 (“very high strength concrete”). The top size of the crushed concretes was 19.1 mm and the size range was 4.75 to 19.1 mm. The characterization was carried out with coarse aggregate liberation, to be prepared and concentrated in a gravity concentration process. The density distribution of the coarse aggregate, cement paste, and sand was carried out in different size ranges (4.75/19.1 mm; 4.75/8.0 mm; 8.0/12.5 mm; and 12.5/19.1 mm) for the three concretes studied. The form factor of the samples, as well as the porosity determination of particles in different density ranges, are presented. The obtained results indicate that the coarse aggregate liberation was more intensive for the low resistance concrete (C16/20), but a reasonable coarse aggregate recovery is possible for all concretes
Anthrax Edema Toxin Modulates PKA- and CREB-Dependent Signaling in Two Phases
Background: Anthrax edema toxin (EdTx) is an adenylate cyclase which operates in the perinuclear region of host cells. However, the action of EdTx is poorly understood, especially at molecular level. The ability of EdTx to modulate cAMPdependent signaling was studied in Jurkat T cells and was compared with that of other cAMP-rising agents: Bordetella pertussis adenylate cyclase toxin, cholera toxin and forskolin. Methodology/Principal Findings: EdTx caused a prolonged increase of the intracellular cAMP concentration. This led to nuclear translocation of the cAMP-dependent protein kinase (PKA) catalytic subunit, phosphorylation of cAMP response element binding protein (CREB) and expression of a reporter gene under control of the cAMP response element. Neither p90 ribosomal S6 kinase nor mitogen- and stress-activated kinase, which mediate CREB phosphorylation during T cell activation, were involved. The duration of phospho-CREB binding to chromatin correlated with the spatio-temporal rise of cAMP levels. Strikingly, EdTx pre-treated T cells were unresponsive to other stimuli involving CREB phosphorylation such as addition of forskolin or T cell receptor cross-linking. Conclusions/Significance: We concluded that, in a first intoxication phase, EdTx induces PKA-dependent signaling, which culminates in CREB phosphorylation and activation of gene transcription. Subsequently CREB phosphorylation is impaired and therefore T cells are not able to respond to cues involving CREB. The present data functionally link the perinuclea
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