Search results for "DF"
showing 10 items of 1699 documents
The cork oak in the Mountains of Palermo (Italy): ecological insights from the south-eastern edge of its distribution range
2020
Abstract: The uneven presence of the cork oak (Quercus suber L.) within its distribution range is not only determined by its climatic requirements but also by specific edaphic needs. Although most of the natural populations thrive in acidic soils deriving from metamorphic or volcanic rock outcrops, some cork oak populations are found growing in soils deriving from calcareous bedrock, which are considered less suitable. We carried out a multidisciplinary investigation at the south eastern edge of the Q. suber distribution range (Mountains of Palermo, NW Sicily), including soil, floristic, and vegetation surveys, aimed at: (i) assessing the native or introduced origin of some peculiar cork oa…
Neglected fishery data sources as indicators of pre‐industrial ecological properties of Mediterranean swordfish ( Xiphias gladius , Xiphiidae)
2022
Management of fish populations and ecosystems suffers from data and knowledge gaps, particularly with respect to how humans and nature affect dynamics at multi-decadal and longer time scales. However, collection of new data which indicates population or ecosystem status is slow and expensive. Here we analyse c. 110 years of neglected fishery data for an overexploited top predator, swordfish, in the Mediterranean Sea. These data are available at scales of high time–space–biological resolution (i.e., sub-weekly, sub-regional sea; individual weights) and allow different ecological questions to be addressed than is possible with coarsely scaled data (e.g., annually resolved total catches aggreg…
VALUTAZIONE DELLA DENSITÀ OSSEA DI UN CAMPIONE DI SOGGETTI PARAPLEGICI. RUOLO DEL DOTTORE IN SCIENZE MOTORIE NEL RECUPERO DELL’AUTONOMIA MOTORIA.
2008
Scopo del lavoro è stato quello di valutare in pazienti maschi paraplegici gli adattamenti del tessuto osseo del rachide in toto e dei vari segmenti scheletrici in conseguenza della prolungata immobilità e di proporre dei nuovi protocolli d’attività motoria che possano sia limitare il decadimento progressivo delle strutture osteo-articolari, sia di preparare i pazienti all’ utilizzo di nuove tecnologie che consentano una pur parziale autonomia motoria. Allo studio hanno partecipato volontariamente venticinque soggetti paraplegici di sesso maschile con lesioni complete T3- L3, suddivisi in due gruppi in relazione agli anni di lesione: il primo gruppo è composto da 13 soggetti con lesione mid…
Anatomia clinica del sistema articolare del piede
2006
From a semantic point of view the word “ankle” and “ankle region” are not synonyms as “ankle” identifies all the components of the ankle joint while “ankle region” identifies the ankle joint as well as every structures in the region, form the surface level to the skeletal one. The articular system of the foot is formed by thirthyfour synovial joints, seventeen of which have complementary curvilinear articular surface, the remaning seventeen having plane joints. The rounded surface joints are: the talonavicular joint (a spheroidal joint that is part of the transverse tarsal joint), the “anatomical” subtalar joint ( a saddle joint), five ellipsoid (or condylar) joints and ten, ankle and inter…
Sequestering ability of landfill leachate towards toxic metal ions
2017
The great part of municipal solid wastes is worldwide stored in sanitary landfills. The interaction of organic and inorganic wastes with rainwater produces in the landfill a leachate of extremely variable composition. It depends on several variables such as the type of wastes, the age of landfill, the pH, the redox potential, etc [1-2]. Four are the recognized categories of pollutants in landfill leachate: inorganic macrocomponents, dissolved organic matter (DOM), heavy metals and xenobiotic organic compounds [3]. In particular, heavy metals (arsenic, cadmium, copper, lead, mercury, etc.) are usually present at concentration of few ppb and up to some ppm. A variable but consistent fraction …
Theoretical Investigation of Aqueous Phase Reforming of 1,2 Propanediol over a Pt catalyst
2015
Aqueous Phase Reforming (APR) process is one of the most efficient solution for producing hydrogen from biomass renewable feedstocks, such as polyalcohols. [1] Generally the reaction is catalyzed by supported platinoid metals and among these platinum has been recognized as the most active and selective toward the production of hydrogen. However, due to its really high complexity, the reaction mechanism is today poorly understood. DFT methods can be useful for understanding the APR catalytic mechanism at atomistic level. A detailed mechanistic study was carried out using a Pt30 cluster for the modelization of the catalyst and 1,2 propanediol (1,2PDO) as a model feedstock for the APR. Even fo…
Palladium clusters on BNNT as catalysts for biomass conversion
2015
The construction of a heterogeneous catalytic systems by a bottom-up approach is a fascinating strategy well assisted by molecular level characterizations. In this sense, DFT investigations can be used with predictive and descriptive purposes both for the treatment of the catalyst/support and for the substrate/catalyst characterization. This should be particularly useful for highly perspective but scarcely treated systems such as boron nitride based supports. Among these, boron nitride nanotubes (BNNT) have been demonstrated to have high chemical and thermal stability as well as great mechanical strength and high thermal conductivity.[1] Moreover, a high affinity toward hydrogen [2] as well…
Computational study of metal-free N-doped carbon networks as hydrogenation catalysts
2015
The future development and assesment of an industry more environmental friendly will include the use of metal-free catalysts. Most of the reported metal-free catalysts are homogeneous and often their recycle is difficult; therefore, develop and investigate them is of interest both theoretical and experimental. Recently, N-doped nanotubes and graphene sheets, were synthesized [1,2], and it was demonstrated that the incorporation, within these carbon structures, of nitrogen atoms causes a greater electron mobility and introduces more active sites for catalytic reactions. This investigation is aimed at elucidating the main features of the hydrogen fragmentation over these carbon frameworks. Se…
Computational Investigation of Palladium Supported Boron Nitride Nanotube Catalysts
2015
A QM/MM investigation is reported dealing with the nucleation and growth of small palladium clusters, up to Pd8 , on the outer surface of a suitable model of boron nitride nanotube (BNNT). It is shown that the BNNT could have a template effect on the cluster growth, which is due to the interplay between Pd-N and Pd-Pd interactions as well as to the matching of the B3N3 ring and the Pd(111) face arrangement. The values for the clusters adsorption energies reveal a relatively strong physisorption, which suggests that in particular conditions the BNNTs could be used as supports for the preparation of shape-controlled metal cluster
DFT investigation of polyalcohols reforming on palladium cluster
2015
Biomass conversion technologies have recently gained high industrial interest for the production of sustainable fuels and fine chemicals; starting feedstocks for these processes are generally complex mixtures of oxygenated compounds, ranging from lignans, carbohydrates and polyalcohols to carboxylic acids [1]. Framed within this scientific context the entire reforming mechanism of two well-known polyols, namely ethylen glycol (C2) and glycerol (C3), on a small Pd cluster was investigated by means of density functional theory. Among the large amount of reaction pathways that can be followed in the reforming of oxygenates, we discuss here only the route that brings to carbon monoxide and hydr…