La résorption de l’azote et du phosphore chez deux espèces décidues sympatriques le long d’un gradient altitudinal

Some leaf traits (N and P concentrations, N/P ratio, specific leaf area, mean residence time of nitrogen and phosphorus (MRTN and MRTP ) and foliar resorption were investigated in two sympatric deciduous species (Amelanchier rotundifolia (Lam.) Dum.-Courset subsp. rotundifolia and Rhamnus oleoides L. subsp. graecus) which are the most characteristic species of steppe and rocky vegetation along an elevation gradient to determine which leaf traits were related to nitrogen and phosphorus efficiency (NRE and PRE) and proficiency (NRP and PRP). Statistically significant differences were found along the elevation gradient between the two sympatric deciduous species with respect to green leaf N/P ratio, NRE , MRTN , MRTP and leaf longevity. NRE was below the threshold values for deciduous species in A. roundifolia subsp. rotundifolia although PRE was higher than threshold values. Both NRE and PRE were higher than threshold values for deciduous species in R. oleoides subsp. graecus. Soil phosphorus concentrations were found to be rather low along the elevation gradient. Leaf N/P ratios varied between 25.54 and 37.11 in A. rotundifolia subsp. rotundifolia, and 11.59 to 21.96 in R. oleoides subsp. graecus and these values indicate P rather than N-limitation for these species. As with NRE and PRE mean residence time of nutrients (MRT ) both MRTN and MRTP were considerably higher in R. oleoides subsp. graecus. It has been found that A. rotundifolia subsp. rotundifolia has low green leaf P concentration and high N/P ratio and has a CS (competitor/ stress-tolerant) strategy, whilst R. oleoides subsp. graecus has a C/CS (competitor/ competitor stress-tolerant) transitional type strategy In conclusion, higher MRTN and MRTP would provide a competitive advantage of a certain species in mixed-deciduous species stands and also enable higher PRE along an elevation gradientQuelques traits foliaires (concentrations en N et P, N/P ratio, surface foliaire spécifique, temps moyen de résidence de l'azote et du phosphore (MRTN et MRTP) et résorption foliaire) ont été étudiés chez deux espèces décidues sympatriques (Arnelanchier rotundifolia (Lam.) Dum.-Courset subsp. rotundifolia et Rhamnus oleoides L. subsp. graecus) qui sont les espèces les plus caractéristiques de la végétation steppique et rupicole le long d'un gradient altitudinal et cela pour déterminer quels traits foliaires sont liés à l'efficience (NRE et PRE) et à la capacité (NRP et PRP) en azote et phosphore. Des différences statistiquement significatives ont été trouvées le long du gradient altitudinal entre les deux espèces pour ce qui concerne le N/P ratio des feuilles vertes, NRE, MRTN, MRTP et la longévité foliaire. NRE était sous les valeurs-seuils des espèces décidues pour A. rotundifolia subsp. rotundifolia bien que PRE était plus élevé que les valeurs-seuils. Tant NRE que PRE étaient plus élevés que les valeurs-seuils des espèces décidues pour R. oleoides subsp. graecus. Les concentrations en phosphore du sol sont apparues plutôt faibles au long du gradient altitudinal. Les N/P ratios foliaires variaient entre 25,54 et 37,11 chez A. rotundifolia subsp. rotundifolia et entre 11,59 et 21,96 chez R. oleoides subsp. graecus ; ces valeurs indiquent une limitation par P plutôt que par N chez ces espèces. Comme pour NRE et PRE, les temps moyens de résidence des nutriments (MRTN et MRTP) étaient considérablement plus élevés chez R. oleoides subsp. graecus. A. rotundifolia subsp. rotundifolia a montré une faible concentration en P dans les feuilles vertes et un fort N/P ratio et a une stratégie CS (compétiteur / tolérant au stress) alors que R. oleoides subsp. graecus a un type de stratégie de transition C/CS (compétiteur / compétiteur ― tolérant au stress). En conclusion des MRTN et MRTP élevés fourniraient un avantage compétitif à certaines espèces décidues dans des peuplements mixtes et permettraient de plus forts PRE le long d'un gradient altitudinal

Stability and Reversible Oxidation of Sub-Nanometric Cu5 Metal Clusters: Integrated Experimental Study and Theoretical Modeling**

Sub-nanometer metal clusters have special physical and chemical properties, significantly different from those of nanoparticles. However, there is a major concern about their thermal stability and susceptibility to oxidation. In situ X-ray Absorption spectroscopy and Near Ambient Pressure X-ray Photoelectron spectroscopy results reveal that supported Cu5 clusters are resistant to irreversible oxidation at least up to 773 K, even in the presence of 0.15 mbar of oxygen. These experimental findings can be formally described by a theoretical model which combines dispersion-corrected DFT and first principles thermochemistry revealing that most of the adsorbed O2 molecules are transformed into superoxo and peroxo species by an interplay of collective charge transfer within the network of Cu atoms and large amplitude “breathing” motions. A chemical phase diagram for Cu oxidation states of the Cu5-oxygen system is presented, clearly different from the already known bulk and nano-structured chemistry of Cu

Screening of Heterogeneous Photocatalysts for Water Splitting

In this contribution, a simple method for the screening of photocatalytic activity of catalyst materials is presented. The method is based on two steps the immobilization of the photocatalyst and the subsequent testing of their photocatalytic activity, using the gas evolution at the solid liquid interface. Up to four catalysts can be tested under the same conditions. The observed gas evolution for selected photocatalysts is consistent with trends reported in the literature from conventional photocatalytic reactor

Stability and Reversible Oxidation of Sub-Nanometric Cu5 Metal Clusters: Integrated Experimental Study and Theoretical Modeling

12 pags., 6 figs.Sub-nanometer Metal clusters have special physical and chemical properties, significantly different from those of nanoparticles. However, there is a major concern about their thermal stability and susceptibility to oxidation. In situ X-ray Absorption spectroscopy and Near Ambient Pressure X-ray Photoelectron spectroscopy results reveal that supported Cu5 clusters are resistant to irreversible oxidation at least up to 773 K, even in the presence of 0.15 mbar of oxygen. These experimental findings can be formally described by a theoretical model which combines dispersion-corrected DFT and first principles thermochemistry revealing that most of the adsorbed O2 molecules are transformed into superoxo and peroxo species by an interplay of collective charge transfer within the network of Cu atoms and large amplitude "breathing" motions. A chemical phase diagram for Cu oxidation state of the Cu5-oxygen system is presented, clearly different from the already known bulk and nano-structured chemistry of Cu.This work has been partly supported by the Spanish Ministerio de Ciencia e Innovación (TED2021-131899BI00/MCIN/AEI/10.13039/501100011033/ Unión Europea NextGenerationEU/PRTR), and the Agencia Estatal de Investigación (AEI) and the Fondo Europeo de Desarrollo Regional (FEDER, UE) under Grants Nos, PID2019-107115GBC21, and PID2020-117605GB-I00; the EU Doctoral Network PHYMOL 101073474 (project call reference HORIZON-MSCA2021-DN-01); the Austrian Science Fund (FWF) under Grant P29893-N36; XUNTA DE GALICIA (Spain) (Grupos Ref. Comp. 2021 - ED431C 2021/16); ANPCyT PICT (2017-1220 and 2017- 3944) and UNLP (Project 11/X937), Argentina. This publication is also based upon work of COST Action CA21101 "Confined molecular systems: from a new generation of materials to the stars" (COSY) supported by COST (European Cooperation in Science and Technology).Peer reviewe

Urban hedges: a review of plant species and cultivars for ecosystem service delivery in north-west Europe

Urban hedges provide a number of important ecosystem services (ESs) including microclimate alteration, flood and pollution mitigation, and biodiversity provision, along with some disservices (DSs, e.g. invasiveness, allergenicity). However, hedge plant species differ in their capacity to promote different services, so it is important that the decision to plant hedges is evidence-based. The objectives of this study were thus to (i) to review the role of urban hedges within NW Europe; (ii) review the available literature detailing the ESs and DSs provided by different plant species and cultivars when used as hedge plants; (iii) identify where there is a lack of evidence for certain species or ESs/DSs; and (iv) develop a starting point for a discussion about appropriate species/cultivar selection to deliver multiple ESs, and avoid DSs. Many studies consider biodiversity and air quality ESs. There are significant gaps in the literature relating to rainfall mitigation/flood protection, but also CO2 sequestration, allergenicity and human psychological well-being impact of different species. Additionally, for noise and pollution mitigation studies, a range of methodologies and units are used, making comparisons between hedge species difficult/impossible. A number of common hedge species demonstrated high levels of ESs delivery, including Fagus sylvatica, Crataegus monogyna, Ilex aquifolium and Rosa rugosa. No species surveyed had an entirely negative association with ESs, and most provide at least some benefits in supporting ESs provision (e.g. Viburnum tinus, Laurus nobilis). We created a matrix, in a table form, linking plant species, key plant traits and ESs/DSs, which should make it easier for professionals to choose species best suited to provide multiple benefits, whilst minimising the drawbacks. Our review suggests that the relative contribution of urban hedges to ESs delivery may be under-valued currently, and calls for more research

Foliar resorption in

• The resorption of nutrients (mainly N and P) from senescing leaves may be a key component of adaptive mechanisms that conserve scarce nutrients. Resorption may be expressed in two ways as resorption efficiency (RE) which is the ratio of the resorbed amounts of nutrient losses during leaf senescence in relation to its prior amount deposited in leaves and resorption proficiency (RP) is the level to which nutrient concentration per unit leaf mass is reduced in senescent leaves. • There is still much debate whether or not different life-forms (i.e. deciduous and evergreen species) show different foliar resorption patterns. Two sympatric species, namely Quercus petraea (Mattuschka) Liebl. subsp. iberica (Steven ex Bieb.) Krassiln. (deciduous) and Arbutus andrachne L. (evergreen) along an elevational gradient were compared with each other to determine whether or not nitrogen and phosphorus resorption efficiency and proficiency varies along the elevational gradient and which leaf parameters were as related to RE and RP. • NRE was found to be rather low in Q. petraea subsp. iberica compared to other deciduous species. Similarly, PRE in A. andrachne was rather low compared to other evergreen species. Mean residence time (MRT) measures how long a unit of nitrogen (MRTN) and phosphorus (MRTP) is present in the plant. MRTN and MRTP were found to be considerably higher in A. andrachne compared to Q. petraea subsp. iberica. In both species, the foliar N/P ratio was below 14 along the elevational gradient and, according to this threshold value, N-limitation occurred in the study area. Although both species in the present study show incomplete resorption deciduous species was more proficient as compared to evergreen one due to low N and P concentrations in senescent leaves. Based on the significant correlations (p < 0.05 and 0.01) between MRT and foliar resorption, it can be concluded that MRT could interfere with the mechanisms controlling nutrient resorption

Nitrogen and phosphorus resorption in two sympatric deciduous species along an elevation gradient

Some leaf traits (N and P concentrations, N/P ratio, specific leaf area, mean residence time of nitrogen and phosphorus (MRTN and MRTP) and foliar resorption were investigated in two sympatric deciduous species (Amelanchier rotundifolia (Lam.) Dum.-Courset subsp. rotundifolia and Rhamnus oleoides L. subsp. graecus) which are the most characteristic species of steppe and rocky vegetation along an elevation gradient to determine which leaf traits were related to nitrogen and phosphorus efficiency (NRE and PRE) and proficiency (NRP and PRP). Statistically significant differences were found along the elevation gradient between the two sympatric deciduous species with respect to green leaf N/P ratio, NRE, MRTN, MRTP and leaf longevity. NRE was below the threshold values for deciduous species in A. roundifolia subsp. rotundifolia although PRE was higher than threshold values. Both NRE and PRE were higher than threshold values for deciduous species in R. oleoides subsp. graecus. Soil phosphorus concentrations were found to be rather low along the elevation gradient. Leaf N/P ratios varied between 25.54 and 37.11 in A. rotundifolia subsp. rotundifolia, and 11.59 to 21.96 in R. oleoides subsp. graecus and these values indicate P rather than N-limitation for these species. As with NRE and PRE mean residence time of nutrients (MRT) both MRTN and MRTP were considerably higher in R. oleoides subsp. graecus. It has been found that A. rotundifolia subsp. rotundifolia has low green leaf P concentration and high N/P ratio and has a CS (competitor/stress-tolerant) strategy, whilst R. oleoides subsp. graecus has a C/CS (competitor/competitor stress-tolerant) transitional type strategy In conclusion, higher MRTN and MRTP would provide a competitive advantage of a certain species in mixed-deciduous species stands and also enable higher PRE along an elevation gradient.La résorption de l’azote et du phosphore chez deux espèces décidues sympatriques le long d’un gradient altitudinal. Quelques traits foliaires (concentrations en N et P, N/ P ratio, surface foliaire spécifique, temps moyen de résidence de l’azote et du phosphore (MRTN et MRT P) et résorption foliaire) ont été étudiés chez deux espèces décidues sympatriques (Amelanchier rotundifolia (Lam.) Dum.-Courset subsp. rotundifolia et Rhamnus oleoides L. subsp. graecus) qui sont les espèces les plus caractéristiques de la végétation steppique et rupicole le long d’un gradient altitudinal et cela pour déterminer quels traits foliaires sont liés à l’efficience (NRE et PRE) et à la capacité (NRP et PRP) en azote et phosphore. Des différences statistiquement significatives ont été trouvées le long du gradient altitudinal entre les deux espèces pour ce qui concerne le N/P ratio des feuilles vertes, NRE, MRTN , MRTP et la longévité foliaire. NRE était sous les valeurs-seuils des espèces décidues pour A. rotundifolia subsp. rotundifolia bien que PRE était plus élevé que les valeurs-seuils. Tant NRE que PRE étaient plus élevés que les valeurs-seuils des espèces décidues pour R. oleoides subsp. graecus. Les concentrations en phosphore du sol sont apparues plutôt faibles au long du gradient altitudinal. Les N/P ratios foliaires variaient entre 25,54 et 37,11 chez A. rotundifolia subsp. rotundifolia et entre 11,59 et 21,96 chez R. oleoides subsp. graecus ; ces valeurs indiquent une limitation par P plutôt que par N chez ces espèces. Comme pour NRE et PRE, les temps moyens de résidence des nutriments (MRTN et MRTP ) étaient considérablement plus élevés chez R. oleoides subsp. graecus. A. rotundifolia subsp. rotundifolia a montré une faible concentration en P dans les feuilles vertes et un fort N/P ratio et a une stratégie CS (compétiteur / tolérant au stress) alors que R. oleoides subsp. graecus a un type de stratégie de transition C/CS (compétiteur / compétiteur – tolérant au stress). En conclusion des MRTN et MRTP élevés fourniraient un avantage compétitif à certaines espèces décidues dans des peuplements mixtes et permettraient de plus forts PRE le long d’un gradient altitudinal.Duygu Kilic Dudu, Güray Kutbay Hamdi, Ozbucak Tuğba, Huseyinova Rena. Nitrogen and phosphorus resorption in two sympatric deciduous species along an elevation gradient. In: Revue d'Écologie (La Terre et La Vie), tome 67, n°4, 2012. pp. 409-422

The effect of cytokines (TNF-alpha; IL-1) and PAF on lipid profile during systemic infection in children

WOS: 00008292970005

Ellenberg's indicator values for soil nitrogen concentration and pH in selected swamp forests in the Central Black Sea region of Turkey

WOS: 000342607700006Ellenberg developed a system that assigns indicator scores for habitat characteristics of individual plant species. Swamp forests are highly diverse ecological communities and include different plant species, all of which have different ecological requirements. Ellenberg's indicator values (EIVs) were calculated for soil pH and nitrogen (N) concentration in some swamp forest species in the Central Black Sea region of Turkey. In this study, the EIVs for soil pH were usually similar in the swamp forest species studied, while some differences were found with respect to EIVs for soil nitrogen concentration. Tolerance values (TVs) of all of the studied species were higher than those reported in similar studies because EIVs and species abundance were high in the present study compared to similar studies. TVs (soil pH) were higher in Galeric Forest than in the other 2 swamp forests. The differences among the swamp forest species studied with respect to EIVs might be explained on the basis of soil heterogeneity, even on a local scale