Search results for "narG"

Stereoselective synthesis of the published structure of synargentolide A and of one of its stereoisomers

2005

A stereoselective synthesis is described of the structure published for the naturally occurring synargentolide A, an α,β-unsaturated lactone. The key steps of the synthesis were a Brown´s asymmetric allylation and a ring closing metathesis. The spectroscopic data of the synthetic product were very close to those of the natural product but did not exactly match them. An epimer of the published structure was then synthesized according to a similar strategy. Again, the data of the synthetic product did not match those reported for the natural product. It is thus likely that the actual structure of synargentolide A differs from the published one in more than mere stereochemical aspects. Marco V…

Evaluation of an Optical Energy Harvester for SHM Application

2019

Abstract In this paper a preliminary study on an array configuration of rectified optical nanoantennas for energy harvesting application is proposed. Currently, the major impediments for the use of the rectified optical nanoantenna known as rectenna are the relatively low conversion efficiency and low power transfer to the load, both of them caused mainly by the mismatch between the impedance of the rectifier (several kilo ohms) and that of the antenna (hundreds of ohm). For this reason, the design of the array represents a crucial point to obtain the maximum energy transfer from the rectenna to the load, represented as a typical DC/DC boost power converter, and modeled by an equivalent inp…

The Construction of Collective Memory: from Franco to Democracy

2004

Collective memory is neither spontaneous nor random, but the result of a series of selective practices. It establishes group identity and sets power relations between groups. The author considers the process of selection through a case study of the transformation of Franco’s regime in Spain into a democracy. Collective memory of the time is shown to be organized around an event (the Munich Coalition or contubernio) and around the democratic transition. The author traces two opposing notions, negationist (denying any importance to Munich) and the pro-democratic, and concludes that the memory of the transition is only the memory of those who won the civil war, who were also those who enginee…

La construcción de la memoria colectiva: un ejemplo concreto

2004

La versión que aquí se facilita es el texto mecanografiado por el autor, que coincide con la versión publicada en la revista "Diogène". Este artículo también está disponible en versión francesa (en: Diogène, nº 201, 2003/1, pp. 17-28) e inglesa (en: Diogenes, nº 201, vol. 51, issue 1, 2004, pp. 17-26)

La construction de la mémoire collective. Du franquisme à la démocratie

2003

Tambien disponible en version espanola (en: Diogenes, no 201, marzo de 2004) e inglesa (en: Diogenes, no 201, vol. 51, issue 1, 2004, pp. 17-26)

Floristic traits and biogeographic characterization of the Gennargentu massif (Sardinia)

2013

A study on the vascular flora of the Gennargentu Massif (Central-Eastern Sardinia) is presented. According to our results, the flora consists of 948 taxa: 686 species, 249 sub- species, 10 varieties and 3 hybrids, belonging to 97 families and 427 genera. Three taxa are new findings for the flora of Italy and eight for that of Sardinia. Life form analysis revealed, in particular, dominance of 35.65 % hemicryptophytes, 34.6 % therophytes, 12.13 % geophytes and 11.6 % (nano)-phanero- phytes. As concerns chorology, the Mediterranean element is largely prevailing (68.14%), mainly represented by circum- Medit. (29.1 %) and Euro-Medit. (23.07 %). Endemics are 14.87% of the whole flora (141 taxa), …

Dénitrification et émission de N2O par des sols soumis à une fertilisation organique ou minérale. Cas des effluents porcins

2007

Les effets des apports à long terme (9 ans) de lisier de porc ou de nitrate d’ammonium sur l’activité énitrifiante, la production de N2O et le carbone organique du sol (C extractible, C de la biomasse microbienne et C organique total) ont été comparés sur des parcelles adjacentes à trois profondeurs différentes. L’activité dénitrifiante a été mesurée sur des cylindres de sol non remanié et sur des échantillons de sol tamisés avec la méthode à l’acétylène afin d’estimer la vitesse de dénitrification aux conditions du champ ou en conditions potentielles. Les applications de lisier ont eu un effet modéré sur les pools de C. La teneur en C organique total a été augmentée de 6,5% et la taille de…

Traking nitrate reducers and denitrifiers in the environment

2005

The ability to respire nitrate when oxygen is limited has been described in taxonomically diverse microorganisms including members of the alpha-, beta-, gamma- and epsilon-proteobacteria, high and low GC Gram-positive bacteria and even Archaea. Respiratory nitrate reduction is the first step of the denitrification pathway, which is important since it is the main biological process responsible for the return of fixed nitrogen to the atmosphere, thus completing the nitrogen cycle. During the last decade, considerable knowledge has been accumulated on the biochemistry and genetics of the nitrate reductases. In this paper, we summarize the recent progress in molecular approaches for studying th…

Abundance of narG, napA, nirK and nosZ genes of denitrifying bacteria in a Norway spruce forest under different N-deposition

2007

Functional stability of the nitrate-reducing community in grassland soils towards high nitrate supply

2006

Abstract To study the effects of short-term fluctuation of nitrate concentrations on the nitrate-reducing community, repacked soil cores were amended with 0, 100 and 300 μ g NO 3 - ‐ N g - 1 soil and incubated for 3, 7 and 14 days, respectively. The nitrate reductase activity was determined in a laboratory-based enzyme assay. In parallel, the community structure of nitrate-reducing microorganisms was characterised by RFLP-PCR using the functional gene narG , which encodes the catalytic site of the membrane-bound nitrate reductase. The community structure remained constant over the experimental period indicating that this functional community is characterised by a high resistance towards flu…