92 research outputs found
Research Concerning the Fighting of Polystigma rubrum Fungi under the Climate Conditions of Șomcuta Mare Area
In this study, our goal was to survey the influence of the climate conditions, the behavior of the Centenar and Anna Spath varieties on the attack of the Polystigma rubrum fungi during the two experimental years (2013, 2014), in order to make recommendations for new plantations. Nine fungicides were tested, being determined their biologic efficiency, in order to identify the most efficient products. The experimental research was performed during 2013 and 2014, in a fruit tree farm belonging to SC Pomicola SA trade company in Somcuta Mare, Maramures county. The attack was calculated by determining the frequency, intensity and the attack degree. The agrometeorological data were recorded using the AgroExpert system, for surveying the biology of fungi. The linear-interrupted laying method was used, each made up of 5 plants/variant in three repetitions/product. The biologic efficiency of the tested products was lower at the Anna Spath variety than at the Centenar variety due to its sensitivity; the recommended products: Folicur Solo 250EW, Dithane M45 and Syllit 400 SC were the most efficient in the fungi combating
Towards more sustainable synthesis of diketopyrrolopyrroles
The alkylation of 1,4-diketo-3,6-arylpyrrolo[3,4-c]pyrroles (ArDPP) is one of the most important steps in the synthesis of soluble materials based on these molecules and the polymers derived from them (that are employed widely in putative organic solar cells). Here we report an improvement in their method of synthesis replacing habitual solvent and base. Compared with more usual conditions, we employed acetonitrile as solvent to give higher or similar yields, with less toxic and hazardous waste, lower reaction time and temperature, and allows recycling of unreacted starting materials. Unlike dimethylformamide and N-methylpyrrolidone, which are the most commonly employed solvents. Our reaction conditions have been tested on three different ArDPPs (Ar = thiophene, phenyl and 4-methoxyphenyl) with a variety of linear and branched alkyl reagents. The results show similar and improved results in comparison with the published reports while reducing the waste and hazard of the reaction, as well as simplifying the purification of the products in many cases. Overall this method has lower environmental impact, is more cost effective and requires neither the use of dry solvent nor inert atmosphere
Solid state supramolecular structure of diketopyrrolopyrrole chromophores: correlating stacking geometry with visible light absorption
Mono- and di-alkylated 1,4-diketo-3,6-dithiophenylpyrrolo[3-4-c]pyrrole derivatives (TDPPs) have been synthesised and their solid state packing and absorption properties have been correlated. In this library of compounds the bulkier substituents distort the geometry of the chromophores and shift the lowest energy absorption band as a consequence of reduced π–π stacking and inter-chromophore overlap. Longitudinal displacement of the conjugated core is affected by donor–acceptor intermolecular interactions and twisting of the thiophene ring out of the plane of the DPP core, whereas lateral displacement was correlated to distortion of the NLactam–C(R) bond out of the plane of the DPP core. The di-substituted TDPP with hexyl units exhibit high molecular planarity, strong close packing of the conjugated core and significant red shift of the maximum of absorption in the solid, whereas the mono-substituted compounds with hexyl and ethyl acetate units are the least distorted of the series because of strong intermolecular hydrogen bonding that increases the molecular overlap and planarity of the chromophores. Therefore the family of mono-substituted TDPPs and more specifically the ones with ethyl acetate substituents show good potential for modulating the molecular geometry and optimizing the charge transport in materials for organic electronic applications
Monitoring the Edible Chestnut Bark Cancer (Cryphonectria Parasitica) and its Prevention and Combat Measures in the Pedoclimatic Conditions of the Baia Mare Basin
Our research aims to assess the chestnut tree health status in three various locations: Baia Mare, Tauti Magheraus, Baia Sprie, in order to find the most efficient methods to prevent and to combat the bark cancer which develops in the clime conditions of Baia Mare basin. The primary assessment was performed through the determination of the attack degree (AD %), of its frequency (F%) and its intensity (I%) . We took in observation 10 chestnut trees from each location. We determined the number and size of both trunk and branches lesions for each chestnut tree. The intensity of the attack in the three studied areas ranked from the highest intensity 47.5% for Baia Sprie location followed by the intensity of 33.0 % for Tautii Magheraus, to the intensity of 26.5% for Baia Mare. Our analysis performed after the administration of the combat chemical method, we found that this measure was not efficient because the infection did not diminish; thus we recommend the dry chestnut tree elimination, its hygiene cuts, using the biologic combat
In Search of Chiral Molecular Superconductors: κ-[(S,S)-DM-BEDT-TTF]2ClO4 Revisited
The relationship between chirality and superconductivity is an intriguing question. The two enantiomeric crystalline radical cation salts κ-[(S,S)-DM-BEDT-TTF]2ClO4 and κ-[(R,R)-DM-BEDT-TTF]2ClO4, showing κ-type arrangement of the organic layers, are investigated in search for superconducting chiral molecular materials following a 1992 report indicating the occurrence of a superconducting transition in the former compound. While the initial interpretation is presently challenged through in-depth temperature and pressure dependent single crystal resistivity measurements combined with band structure calculations, the two chiral conductors show metal like behavior with room temperature conductivities of 10-30 S cm−1 at ambient pressure and stabilization of the metallic state down to the lowest temperatures under moderate pressures. Moreover, their structural and theoretical investigations reveal an original feature, namely the existence of two different κ layers with 1D and 2D electronic dimensionality, respectively, as a consequence of an interlayer charge transfer. The resistivity drop observed for one sample below 1 K and insensitive to magnetic field, possibly results from mixing in-plane and out-of-plane contributions to the measured resistance and suggests current induced charge order melting. This feature contradicts the occurrence of superconductivity in these chiral molecular conductors and leaves open the discovery of the first chiral molecular superconductors
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