Bulgarian Academy of Sciences

About: Bulgarian Academy of Sciences is a government organization based out in Sofia, Bulgaria. It is known for research contribution in the topics: Catalysis & Coupling constant. The organization has 17989 authors who have published 36276 publications receiving 642820 citations. The organization is also known as: Bulgarian Academy of Sciences，簡稱：BAS & Balgarska Akademiya na Naukite.

FTIR Study of CO Adsorption on Ni−ZSM-5

Abstract: Adsorption of CO on Ni−ZSM-5 reveals the existence of two kinds of Ni2+ ions, with the respective stretching frequencies being at 2220 and 2212 cm-1. The carbonyl complexes are resistant to evacuation at room temperature, which is explained by the high electrophilicity of cations in a ZSM matrix. At 85 K and in the presence of CO, part of the Ni2+−CO species are converted into Ni2+(CO)2 dicarbonyls (2204 cm-1) which are characterized by a very low stability and easily lose one of their CO ligands. Interaction of Ni−ZSM-5 with CO at 673−773 K results in a preferential reduction of the Ni2+ ions which form the carbonyls characterized by the band at 2220 cm-1. CO adsorption at room temperature on the reduced sample leads to the formation of Ni+(CO)2 gem dicarbonyls (νs at 2136 cm-1 and νas at 2092 cm-1) which are converted, during evacuation, to linear Ni+−CO species (2109 cm-1). The dicarbonyl structure is proved by 12CO−13CO coadsorption, and the mixed Ni+(12CO)(13CO) species are characterized by ν(12CO) a...

Diversity of European seagrass indicators: patterns within and across regions

Abstract: Seagrasses are key components of coastal marine ecosystems and many monitoring programmes worldwide assess seagrass health and apply seagrasses as indicators of environmental status. This study aims at identifying the diversity and characteristics of seagrass indicators in use within and across European ecoregions in order to provide an overview of seagrass monitoring effort in Europe. We identified 49 seagrass indicators used in 42 monitoring programmes and including a total of 51 metrics. The seagrass metrics represented 6 broad categories covering different seagrass organizational levels and spatial scales. The large diversity is particularly striking considering that the pan-European Water Framework Directive sets common demands for the presence and abundance of seagrasses and related disturbance-sensitive species. The diversity of indicators reduces the possibility to provide pan-European overviews of the status of seagrass ecosystems. The diversity can be partially justified by differences in species, differences in habitat conditions and associated communities but also seems to be determined by tradition. Within each European region, we strongly encourage the evaluation of seagrass indicator–pressure responses and quantification of the uncertainty of classification associated to the indicator in order to identify the most effective seagrass indicators for assessing ecological quality of coastal and transitional water bodies.