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Straightforward formation of carbocations from tertiary carboxylic acids: Via CO release at room temperature
No full textLooking for the “Dream Catalyst” for Hydrogen Peroxide Production from Hydrogen and Oxygen
No full textAbstract: The reaction between hydrogen and oxygen is in principle the simplest method to form
hydrogen peroxide, but it is still a “dream process”, thus needing a “dream catalyst”. The aim of this
review is to analyze critically the different heterogeneous catalysts used for the direct synthesis of
H2O2 trying to determine the features that the ideal or “dream catalyst” should possess. This analysis
will refer specifically to the following points: (i) the choice of the metal; (ii) the metal promoters
used to improve the activity and/or the selectivity; (iii) the role of different supports and their acidic
properties; (iv) the addition of halide promoters to inhibit undesired side reactions; (v) the addition
of other promoters; (vi) the effects of particle morphology; and (vii) the effects of different synthetic
methods on catalyst morphology and performance
Sustainability of using vineyard pruning residues as an energy source: Combustion performances and environmental impact
No full textOpen burning of agricultural waste is still a common practice as it is a rapid method for waste disposal, although natural biomass, including agriculture residues, can be exploited as a renewable energy source. We assessed the viability and sustainability of using vineyard pruning residues, as wood chips, for energy conversion. Wood chips, obtained from vineyards in the Prosecco DOCG region (Italy), were characterized in terms of chemical composition, calorific value, ash content and humidity. Combustion tests were performed in a medium-size biomass boiler (maximum power 500 kW) to assess the viability of the approach in terms of sustainable steady-state combustion. Primary emissions of both macro- and micro-pollutants were measured to assess the environmental impact. An analytical method was purposely developed for the determination of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) and in three matrices: fly ashes, condensate and gas. The results showed that vineyard pruning residues can be used for energy conversion in medium- and large-scale biomass boilers. Primary emissions of measured pollutants were all below limit values set by current European legislation except for particulate matter, for which current available abatement technologies are required to contain emissions, abatement technologies are required to contain emissions, thus making the use of vineyard pruning residues unsuitable for combustion in domestic appliances where such technologies are not installed. Bottom ashes produced during combustion were also characterized to assess whether they can be recycled in the vineyard as soil amendments/fertilizer. Copper content in combustion ashes exceeded limit values for ashes to be used as fertilizers in agricultural fields for some European countries but not for others, indicating that ashes may need to be disposed as waste
Recensione a L. Bricault, A. Burnett, V. Drost, A. Suspe`ne (sous la direction de), Rome et les provinces. Monnayage et histoire. Mélanges offerts a`Michel Amandry, Numismatica Antiqua 7, Ausonius E ditions, Bordeaux 2007, 464 pp.; ISBN 9782356131973.
No full textThe co-occurrence of different grassland communities increases the stability of pollination networks
No full textHigh heterogeneity of grassland communities supports a high diversity of species and represents a key point for
the retention of pollinators in agricultural landscapes. In the present study, we explored whether the co-occurrence
of different grassland communities has any effect on the stability of the network of pollination interactions.
We monitored pollination interactions in two co-occurring grassland communities, differing in disturbance
history and water and nutrient supply. The monitoring was carried out during the summer season (7
surveys). For each survey we compared the role in the pollination networks (i.e., keystone vs. peripheral species)
of habitat-specialist and habitat-generalist plant and pollinator species. We found that plant and pollinator
species of the two different grassland communities were highly interconnected, revealing that pollination interactions
occur at a level of organization above that of the single community. The co-occurrence of the two
grassland communities increased the type, number and frequency of contacts, thereby contributing to networks
stability. The role of habitat-specialist and habitat-generalist plant and pollinator species in pollination networks
was asymmetric, with habitat-specialist plants and habitat-generalist pollinators being keystone species, while
habitat-generalist plants and habitat-specialist pollinators being peripheral in the pollination networks. Our
results showed that the stability of the network does stem from the co-occurrence of different species pools
having different but complementary roles in the pollination networks. From a conservation perspective, the
maintenance of different grassland communities is important not only because they allow the conservation of
habitat-specialist species, but specifically because plant species specialized in either grassland community are
also keystone for the maintenance of the stability of the pollination networks
Management Control Systems: Concepts and Approaches
No full textThis chapter examines issues about key concepts and aims of management control. Based on a review of relevant academic literature, the chapter provides an overview of some among the most popular definitions of management control, summarizes different approaches to management control and describes some influential theoretical frameworks
