Potential control of forest diseases by solutions of chitosan oligomers, propolis and nanosilver

There is a growing necessity to replace chemical agents with ecofriendly materials, arising from the impact on the environment and/or human health, which calls for the design of new broad-spectrum fungicides. In this work, chitosan oligomers (COs), propolis (Ps) and silver nanoparticles (AgNPs) mixtures in solution were assessed to control the growth of different phytopathogenic fungi and oomycetes in vitro. Binary solutions of COs-Ps and COs-AgNPs evinced the highest antifungal effect against Fusarium circinatum and Diplodia pinea fungi, respectively, with a ca. 80% reduction in their mycelial growth. The COs solution by itself also proved to be greatly effective against Gremmeniella abietina, Cryphonectria parasitica and Heterobasidion annosum fungi, causing a reduction of 78%, 86% and 93% in their growth rate, respectively. Likewise, COs also attained a 100% growth inhibition on the oomycete Phytophthora cambivora. On the other hand, Ps inhibited totally the growth of Phytophthora ×alni and Phytophthora plurivora. The application of AgNPs reduced the mycelial growth of F. circinatum and D. pinea. However, the AgNPs in some binary and ternary mixtures had a counter-productive effect on the anti-fungal/oomycete activity. In spite of the fact that the anti-fungal/oomycete activity of the different treatments showed a dependence on the particular type of microorganism, these solutions based on natural compounds can be deemed as a promising tool for control of tree diseases

Characterization of the iron-regulated desA promoter of Streptomyces pilosus as a system for controlled gene expression in actinomycetes

BACKGROUND: The bioavailability of iron is quite low since it is usually present as insoluble complexes. To solve the bioavailability problem microorganisms have developed highly efficient iron-scavenging systems based on the synthesis of siderophores that have high iron affinity. The systems of iron assimilation in microorganisms are strictly regulated to control the intracellular iron levels since at high concentrations iron is toxic for cells. Streptomyces pilosus synthesizes the siderofore desferrioxamine B. The first step in desferrioxamine biosynthesis is decarboxylation of L-lysine to form cadaverine, a desferrioxamine B precursor. This reaction is catalyzed by the lysine decarboxylase, an enzyme encoded by the desA gene that is repressed by iron. RESULTS: The binding of the DmdR (acronym for divalent metal dependent repressor) to the desA promoter in presence of Fe(2+ )or other divalent ions has been characterized. A 51 bp DNA fragment of the desA promoter containing the 9 bp inverted repeat was sufficient for binding of the DmdR repressor, as observed by the electrophoretic mobility shift assay. The desA mobility shift was prevented by neutralizing DmdR with anti-DmdR antibodies or by chelating the divalent metal in the binding reaction with 2,2'-dipyridyl. Binding to the desA promoter was observed with purified DmdR repressors of Streptomyces coelicolor or Rhodococcus fascians suggesting that there is a common mechanism of iron-regulation in actinomycetes. The complete desA promoter region was coupled using transcriptional fusions to the amy reporter gene (encoding α-amylase) in low copy or multicopy Streptomyces vectors. The iron-regulated desA promoter was induced by addition of the iron chelating agent 2,2'-dipyridyl resulting in a strong expression of the reporter gene. CONCLUSIONS: The iron-regulated desA promoter can be used for inducible expression of genes in Streptomyces species, as shown by de-repression of the promoter when coupled to a reporter gene

Biorefineries: Achievements and challenges for a bio-based economy

Funding This work was supported by a project (FQM-176) financed by the Junta de Andalucía. FM-M, acknowledges the support from the Global Challenges Research Fund from Swansea University, and from the Royal Society of Chemistry Enablement Grant (E21-7051491439).Climate change, socioeconomical pressures, and new policy and legislation are driving a decarbonization process across industries, with a critical shift from a fossil-based economy toward a biomass-based one. This new paradigm implies not only a gradual phasing out of fossil fuels as a source of energy but also a move away from crude oil as a source of platform chemicals, polymers, drugs, solvents and many other critical materials, and consumer goods that are ubiquitous in our everyday life. If we are to achieve the United Nations’ Sustainable Development Goals, crude oil must be substituted by renewable sources, and in this evolution, biorefineries arise as the critical alternative to traditional refineries for producing fuels, chemical building blocks, and materials out of non-edible biomass and biomass waste. State-of-the-art biorefineries already produce cost-competitive chemicals and materials, but other products remain challenging from the economic point of view, or their scaled-up production processes are still not sufficiently developed. In particular, lignin’s depolymerization is a required milestone for the success of integrated biorefineries, and better catalysts and processes must be improved to prepare bio-based aromatic simple molecules. This review summarizes current challenges in biorefinery systems, while it suggests possible directions and goals for sustainable development in the years to come.Project (FQM-176) financed by the Junta de AndalucíaGlobal Challenges Research Fund from Swansea UniversityRoyal Society of Chemistry Enablement Grant (E21-7051491439

Electron correlation resonances in the transport through a single quantum level

Correlation effects in the transport properties of a single quantum level coupled to electron reservoirs are discussed theoretically using a non-equilibrium Green functions approach. Our method is based on the introduction of a second-order self-energy associated with the Coulomb interaction that consistently eliminates the pathologies found in previous perturbative calculations. We present results for the current-voltage characteristic illustrating the different correlation effects that may be found in this system, including the Kondo anomaly and Coulomb blockade. We finally discuss the experimental conditions for the simultaneous observation of these effects in an ultrasmall quantum dot.Comment: 4 pages (two columns), 3 figures under reques

Ипотека морского судна в контексте восстановление отечественного торгового флота в Украине

Торговельне мореплавство – одна з тих галузей світової економіки, яка має найбільш швидкий розвиток у наш час. Перш за все, це пов’язано із прискоренням міжнародного товарообміну. Наростання обсягів міжнародної торгівлі, у якій прагне приймати участь також Україна, обумовлює необхідність адекватно швидкого зростання її транспортної галузі. Попри значний транспортний потенціал, що має Україна, багато в чому завдячуючи її географічному положенню, стан вітчизняного транспортного комплексу й, особливо, його морської ланки, потребує покращення. Це, в свою чергу, безпосередньо залежить від правового регулювання, що впорядковує такі процеси

Análisis de impactos ambientales producidos durante la fase de ejecución en edificación: operaciones de limpieza y recuperación de aguas de lavado de hormigones en España

The aim of this work is to assess the environmental aspects arising during the execution phase of building construction and to analyse the possibilities of reducing the negative impacts. We have studied the environmental factors associated with the use and handling of the materials, focusing the research on two of the most qualitatively significant processes: operations to clean the works and the recovery of concrete-washing water. In both cases, a qualitative analysis of environmental impact has been made. In the wash-water study, basic parameters (density by differential weighing, pH by pHmeter and chemical composition by X ray fluorescence) of ten samples were analysed to evaluate the quality of the discharges and thus be able to propose solutions and technological improvements (filtering, neutralization,…) applicable to construction works with the aim of decreasing the volume of dislodged solids and improve the quality of water discharged.El presente trabajo evalúa aspectos ambientales durante la fase de ejecución de obra de edificación y analiza las posibilidades de reducción de impactos negativos. Se han estudiado factores ambientales asociados al uso y manipulación de los materiales, centrando la investigación en dos de los procesos cualitativamente más relevantes: las limpiezas de la obra y la recuperación de aguas de lavado de hormigones. En ambos casos se hace un análisis cualitativo de la incidencia ambiental; en el estudio de aguas de lavado se han analizado parámetros básicos (densidad por pesada diferencial, pH mediante pHmetría y composición química por fluorescencia de rayos X) de diez muestras procedentes de distintas obras para evaluar la calidad de los vertidos. Se proponen soluciones aplicables y mejoras tecnológicas (filtrado, neutralización,..) en obra con el fin de disminuir el volumen de sólidos arrastrados y mejorar la calidad del agua vertida