1,215 research outputs found
Synthesis of new pseudo‐C‐nucleosides containing pyrazole rings in their structure
Synthetic approaches to new 4-(furanos-4-C-yl)-1H-pyrazole and 3-(furanos-4-C-yl)-1H-pyrazole derivatives are described, including its pyrazole-5-carboxylate derivative, which is a pyrazofurin analogue. Preparation of related 5-acetoxy-1-acetyl-1H-pyrazole, 5-acetoxy-1H-pyrazole-1-carboxylate, and 4,5-dihydro-1-phenyl-1H-pyrazol-5-one derivatives is also reported. The formation of the pyrazole rings was accomplished either by reaction of enones and of 1,3-diketones with N-nucleophiles or by ring closure of a diazoketone.info:eu-repo/semantics/publishedVersio
Synthesis of phenylseleno sugars from epoxides and of α,β-unsaturated carbonyl derivatives for the study of their insecticidal activity
This work reports the synthesis of sugar epoxides and their derivatives obtained by reaction with the dianion of phenyl selenoacetic acid. Approaches to the introduction of α,β-unsaturated carbonyl units in pyranoid systems were investigated. Preparation of a protected D-glycero-hex-3-enepyranosid-2-ulose and of a D-erythro-hex-2-enono-1,5-lactone is described. Some of the synthesized compounds possess insecticidal activity against fruit flies, house flies, and white flies.Treaty of Windsor Programme, British Council, Ministério da Ciência e do Ensino Superiorinfo:eu-repo/semantics/publishedVersio
Effects of vineyard agricultural practices on the diversity of macroinvertebrates
In Europe, agriculture represents the dominant land use and there is a substantial part of biodiversity associated with those habitats. Therefore, conservation studies should direct to agriculture fields aiming to minimize the biodiversity losses. Vineyards could play a key role in producing win-win solutions for agriculture and biodiversity conservation, as an entrance point of sustainable practices in agriculture management. This study aims to evaluate the influence of different agriculture practices on macroinvertebrate diversity and in the productivity of the vineyards. Comparing these variables, we hope to determine the most sustainable agriculture practices, to suggest conservation measures to enhance sustainability and improve biodiversity in the vineyards. We are comparing Coleoptera, Hymenoptera and Hemiptera diversity and levels of productivity in three differently managed vineyards: conventional, organic and integrated production with controlled doses of chemicals (optidose). Macroinvertebrates will be sampled by pitfalls and colour plates. Study area is Herdade dos Pinheiros of Fundação Eugénio de Almeida, in Évora (Alentejo, Portugal). We expect to find higher macroinvertebrates diversity where there is less disturbance, as in the organic vineyard. And the contrary for the conventional. Also, we are expecting to find little diversity of Hemiptera when there are higher levels of Coleoptera and Hymenoptera diversity, because that means biological control is acting. Finally, we hope to find the best agriculture measures to enhance sustainability and improve biodiversity in vineyards and surrounding areas
Enhancing Electrocatalytic Synthesis of Glycine with CuPb<sub>1ML</sub> Electrode Synthesized via Pb UPD
In the field of reductive organic electrosynthesis, the hydrogen evolution reaction (HER) is considered a parasitic reaction that lowers the Faradaic efficiency of the synthesis. Metals with a high overpotential for HER are often used to prevent this. However, this limits the catalytic materials that can be used in these reactions. To expand upon the scope of available electrocatalysts, we prepared a CuPb electrode via underpotential deposition (UPD). We thereby created an electrocatalyst with a single monolayer of Pb, CuPb1ML, in which Pb weight loading is only 415 ng cm−2, yet its properties could still effectively inhibit HER. The CuPb1ML electrode was used in the electrosynthesis of glycine from oxalic acid and hydroxylamine. This reaction served as a model for a C−N bond forming reaction in acidic aqueous media. The CuPb1ML electrode was compared against a pure Pb and Cu metal electrode. The CuPb1ML electrode showed a Faradaic efficiency for glycine production of 57 %, which was 9-fold higher than Cu and rivaled the Pb electrode. The catalytic activity of CuPb1ML was 211 μmol h−1 cm−2, which is higher than both Cu and Pb. The mechanism of the electroreduction was then studied via in situ Fourier Transform Infra-Red (FTIR) spectroscopy. These results hinted to an evolution of the electrocatalyst during the electrolysis reaction, which was then studied via Scanning Electron Microscopy (SEM) and X-Ray Photoelectron spectroscopy (XPS). We found that the Pb monolayer restructured during catalysis, forming microparticles that were active in the reaction based on the listed experiments. Pb alloying into the lattice, which can occur during UPD, also lowered the HER, further facilitating glycine synthesis. Thus, our research also shows how Pb UPD impacts the catalytic properties of a metal both through monolayer deposition as well as surface alloying.</p
Facile synthesis of oxo-/thioxopyrimidines and tetrazoles C–C linked to sugars as novel non-toxic antioxidant acetylcholinesterase inhibitors
Microwave-assisted synthesis of oxo-/thioxopyrimidines and tetrazoles linked to furanoses with D-xylo
and D-ribo configuration, and to a D-galacto pyranose is reported and compared to conventional methods.
Reaction of dialdofuranoses and dialdopyranoses with a b-keto ester and urea or thiourea under micro wave irradiation at 300 W gave in 10 min the target molecules containing the 2-oxo- or 2-thioxo-pyrimidine ring in high yield. The tetrazole-derived compounds were obtained in two steps by reaction of the
formyl group with hydroxylamine hydrochloride, copper sulfate, triethylamine and dicyclohexylcarbodiimide to give an intermediate nitrile, which was then treated with sodium azide. The use of microwave
irradiation in the latter step also resulted in a considerably shorter reaction time (10 min) compared to
hours under conventional heating to obtain a complete starting materials conversion. Acetylcholinesterase inhibition ranged from 20% to 80% for compounds concentration of 100 lg/mL, demonstrating the
potential of this family of compounds for the control of Alzheimer’s disease symptoms. Most of the compounds showed antioxidant activity in the b-carotene/linoleic acid assay, some of them exhibiting IC50
values in the same order of magnitude as those of gallic acid. The bioactive compounds did not show
cytotoxic effects to human lymphocytes using the MTT method adapted for non-adherent cells, nor geno toxicity determined by the short-term in vitro chromosomal aberration assay.info:eu-repo/semantics/publishedVersio
Life-cycle greenhouse gas emissions of portuguese olive oil
The main goal of this paper was to assess the greenhouse gas (GHG) intensity of olive oil production in Portugal. A life-cycle model and inventory were implemented for the entire production process, including a comprehensive analysis of olive cultivation, olive oil extraction, packaging, and distribution. Data originates from five differently-sized Portuguese olive growers and from a total of six olive oil mills, representing the three extraction processes in use: three-phase extraction, two-phase extraction, and traditional pressing. The results show that the GHG intensity lies in the range 1.8-8.2 kg CO2eq/liter and that the main contributors were fertilizers (production and field emissions). Efficient use of fertilizers thus seems to be a key factor for mitigating the GHG intensity of olive oil production.This research was supported by project ECODEEP (Eco-efficiency and Eco-management in the Agro Industrial sector, FCOMP–05–0128–FEDER–018643) and the Portuguese Scienc
Life-cycle greenhouse gas emissions of portuguese olive oil
The main goal of this paper was to assess the greenhouse gas (GHG) intensity of olive oil production in Portugal. A life-cycle model and inventory were implemented for the entire production process, including a comprehensive analysis of olive cultivation, olive oil extraction, packaging, and distribution. Data originates from five differently-sized Portuguese olive growers and from a total of six olive oil mills, representing the three extraction processes in use: three-phase extraction, two-phase extraction, and traditional pressing. The results show that the GHG intensity lies in the range 1.8-8.2 kg CO2eq/liter and that the main contributors were fertilizers (production and field emissions). Efficient use of fertilizers thus seems to be a key factor for mitigating the GHG intensity of olive oil production
Compilation of parameterized seismogenic sources in Iberia for the SHARE European-scale seismic source model.
Abstract: SHARE (Seismic Hazard Harmonization in Europe) is an EC-funded project (FP7) that aims to evaluate European seismic hazards using an integrated, standardized approach. In the context of SHARE, we are compiling a fully-parameterized active fault database for Iberia and the nearby offshore region. The principal goal of this initiative is for fault sources in the Iberian region to be represented in SHARE and incorporated into the source model that will be used to produce seismic hazard maps at the European scale. The SHARE project relies heavily on input from many regional experts throughout the Euro-Mediterranean region. At the SHARE regional meeting for Iberia, the 2010 Working Group on Iberian Seismogenic Sources (WGISS) was established; these researchers are contributing to this large effort by providing their data to the Iberian regional integrators in a standardized format. The development of the SHARE Iberian active fault database is occurring in parallel with IBERFAULT, another ongoing effort to compile a database of active faults in the Iberian region.
The SHARE Iberian active fault database synthesizes a wide range of geological and geophysical observations on active seismogenic sources, and incorporates existing compilations (e.g., Cabral, 1995; Silva et al., 2008), original data contributed directly from researchers, data compiled from the literature, parameters estimated using empirical and analytical relationships, and, where necessary, parameters derived using expert judgment. The Iberian seismogenic source model derived for SHARE will be the first regional-scale source model for Iberia that includes fault data and follows an internationally standardized approach (Basili et al., 2008; 2009). This model can be used in both seismic hazard and risk analyses and will be appropriate for use in Iberian- and European-scale assessments
Residual feed intake and relationships with performance of Nellore cattle selected for post weaning weight
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