262,323 research outputs found
Influence of photocatalytic systems on the photo-cross-linking of diallyl oxydiethylene dicarbonate grafted onto cellulose
No full textThe photo-cross-linking of 18.4-20.0 μmol of diallyl oxydiethylene dicarbonate (I) grafted onto cellulose (per square contimetre of apparent cellulose surface) was examined kinetically at 30±2 °C, on exposure to an incident polychromatic radiation flux of (2.05±0.08) × 10-7 einstein s-1 cm-2, in the presence of catalytic amounts (20-200 ppm) of three vanadium- (V) organometallic compounds. As with the diacrylate systems studied previously, the kinetics of photo-cross-linking of grafted I followed a multi-relaxation spectrum in terms of two parameters (width of spectrum β and mean lifetime τ). The β values (0.42±0.04) were almost the same in all experiments and were similar to that (0.44±0.02) observed for the thermal decay of double bonds of pre-irradiated I in bulk. The β parameter therefore seems to reflect the cross-linked character of the linear polymer pattern, rather than the cross-linking process, either thermal or photocatalytic. In contrast, the τ values reflect, in a very sensitive manner, the effect of the concentration and type of photocatalytic system employed. An acceleration factor of about 190 was reached with 200 ppm vanadium (synergic mixture of vanadium (V) isopropoxide and isobutoxide). Some relevant features of the photo-cross-linking mechanism are discussed in the light of the proposed kinetic model
Il nazismo, il comunismo e i conti (veri) con la storia
No full textIl dibattito nell' Unione europea sulle memorie del Novecent
Analisi della relazione area-pendenza: alcuni casi di studio nella Provincia Autonoma di Bolzano
No full textIn questa memoria viene proposta un’analisi della relazione area-pendenza, per alcuni bacini
montani della Provincia Autonoma di Bolzano, al fine di una valutazione speditiva, su base
topografica, della propensione a fenomeni di dissesto. Lo studio è stato condotto mediante
l’impiego di modelli digitali del terreno (DTM) ad alta risoluzione ricavati da LiDAR (Light Detection
and Ranging).
Sono stati considerati 13 bacini: in 10 di essi si sono verificati evidenti episodi di colata detritica
durante il 2009, mentre per i rimanenti 3, interessati dai medesimi eventi meteorici, non
vi è alcuna testimonianza di eventi di colata detritica. Dai risultati ottenuti è emerso che nei 10
casi di studio con colata, nella relazione area-pendenza è chiaramente visibile il segno topografico
indicante processi erosivi, di frana e/o colata detritica, risultato consistente con quanto
riportato in letteratura. Nei rimanenti 3 bacini questo segno topografico non è rilevabile. I risultati
ottenuti indicano come la relazione area-pendenza possa effettivamente essere impiegata
per una soddisfacente analisi della propensione ai processi di instabilità quali frane o colate
detritiche. Questa metodologia tuttavia ha la sua validità solo se intesa come analisi preliminare,
di supporto ad applicazioni modellistiche più complesse e fisicamente basate, o anche come
analisi statistica, su scala regionale, per classificare e caratterizzare, sulla base della loro propensione
al dissesto, diversi territori
Second-order nonlinear optical properties of cyclometallated Ir(III) and Pt(II) complexes
No full textThe second-order NLO properties of various cyclometallated cationic Ir(III) and neutral Pt(II) complexes were determined by both Electric Field Induced Second Harmonic generation (EFISH) and Harmonic Light Scattering (HLS) techniques.
Cationic 1,10-phenanthroline and bipyridine iridium(III) complexes (1, 2) are characterized by high negative EFISH β values which decrease when the ion-pair strength between the cation and the counterion (PF6–, C12H25SO3–) increases. Neutral Pt(II) complexes (3, 4) are also characterized by a good to high negative NLO response.
For all these cyclometallated complexes, the EFISH response is mainly controlled by MLCT/L'LCT processes. Interestingly, a combination of HLS and EFISH techniques, used to evaluate both the dipolar and octupolar contributions to the total quadratic hyperpolarizability, shows that the major contribution is controlled by the octupolar part. [...]
1. V. Aubert, L. Ordronneau, M. Escadeillas, J. A. G. Williams, A. Boucekkine, E. Coulaud, C. Dragonetti, S. Righetto, D. Roberto, R. Ugo, A. Valore, A. Singh, J. Zyss, I. Ledoux-Rak, H. Le Bozec, V. Guerchais, Inorg. Chem. 2011. ASA
Comparative structural analysis of haemagglutinin proteins from type A influenza viruses: conserved and variable features.
No full textBackgroundGenome variation is very high in influenza A viruses. However, viral evolution and spreading is strongly influenced by immunogenic features and capacity to bind host cells, depending in turn on the two major capsidic proteins. Therefore, such viruses are classified based on haemagglutinin and neuraminidase types, e.g. H5N1. Current analyses of viral evolution are based on serological and primary sequence comparison; however, comparative structural analysis of capsidic proteins can provide functional insights on surface regions possibly crucial to antigenicity and cell binding.ResultsWe performed extensive structural comparison of influenza virus haemagglutinins and of their domains and subregions to investigate type- and/or domain-specific variation. We found that structural closeness and primary sequence similarity are not always tightly related; moreover, type-specific features could be inferred when comparing surface properties of haemagglutinin subregions, monomers and trimers, in terms of electrostatics and hydropathy. Focusing on H5N1, we found that variation at the receptor binding domain surface intriguingly relates to branching of still circulating clades from those ones that are no longer circulating.ConclusionsEvidence from this work suggests that integrating phylogenetic and serological analyses by extensive structural comparison can help in understanding the `functional evolution¿ of viral surface determinants. In particular, variation in electrostatic and hydropathy patches can provide molecular evolution markers: intriguing surface charge redistribution characterizing the haemagglutinin receptor binding domains from circulating H5N1 clades 2 and 7 might have contributed to antigenic escape hence to their evolutionary success and spreading
"Sarò anche malata, ma qui dentro ho un cuore!" Bambini in Pediatria: un'etnografia
No full textThe main theoretical framework of this research is the new sociology of childhood: it adopts, therefore, the analytical perspective which assumes that children are actors who are capable of acting coherently within their social worlds.
Through an 8 months’ ethnography in the wards of the Paediatric Clinic of the Hospital of Padua, which was conducted in a dialogical style – proposing, thus, to consider the Other as a subject involved in an interaction, even in the process which leads to scientific knowledge, and not as an object from which the researcher can gain experience and gather information – I investigated the relationship hospitalized children establish with adults, within their peer group and the hospital environment, with reference to the illness and to the processes of treatment.
The research explores several themes: the symbolic meanings given by the actors to the space and the places where the interactions come to life; the doctor-patient communication in the paediatric context, paying particular attention to the situations in which this communication takes on characteristics which conflict with the demands and the wishes of the children, who act by putting into action different tactics to collect information about themselves; the relation with the bodies, often considered by adults as objects of the medical practice, bodies which become instead the means children have to exercise their own autonomy and their self-recognition; the issue of competence and agency, developed from the idea that children always possess a situational and relational knowledge, which is specific for the social worlds where they act, but always according to different styles of intervening on the world, which adults sometimes notice with difficulty; the role of the game in the hospital environment, as a particular frame of the action and as a source of sense and meanings.
The main conclusions show how children are always subjects, and are always able to act coherently within their social words, even in a context, such as the hospital one, which seems rigidly binding; how children constantly exercise autonomy and self-recognition, through different tactics, although the medical practice appears to limit their spaces of action, and independently of the manner adults relate to them. The research points out, moreover, how a lack of attention among the adults to the subjectivity of children, to the symbolical meanings in the interactions, can become a strong limit to the effectiveness of the therapeutic relations themselves, to the success of treatment processes which take into account the specificities of children, considered as people and not as objects of the medical practice
How do metropolitan cities evolve after the 2008/2012 crisis and the Covid-19 pandemic? An analysis from real estate market values
No full textItalian cities have been touched by two major events, the 2008 and 2012 crises and the Covid-19 pandemic in 2020 and 2021. The research aimed to verify whether, and in what way, Italian cities have embarked on a path of transformation, outlining their possible trajectories of change in the intervening decade. The cities considered were the metropolitan cities to which the legislature has assigned the role of territorial reference for areas of a regional nature. The research examined real estate market values for their ability to represent a city’s degree of attractiveness in synthetic form. The other variables used made it possible to detect trends in the determinants of the real estate market: economic growth, demographic development and changes in the territorial capital endowment. Concerning the research objectives, cluster analysis appeared to be the most suitable tool to represent changes by aggregating cities according to common patterns. The survey considered the reactions of the different cities in the two five-year periods related to each exogenous shock and, overall, in the decade under review for a long-term reading of the trends. The conclusions reached by the survey show how, between 2012 and 2017, there was a concentration of wealth and population in the major centers and in particular in the city of Milan, characterized by rising property values against a generalized decline in the Italian market. In the second five-year period from 2017 to 2022, the pattern is reproduced with similar intensity, despite a vast debate on the crisis of large cities and their sustainability in the face of the pandemic. An overall ten-year view from 2012 to 2022 of metropolitan cities shows trends with a sufficiently solid and stable character. In the case of Milan, the expression of a clear-cut process of concentration on which the pandemic has had no effect, is counterbalanced by a second cluster of peripheral metropolitan cities that are suffering from processes that penalize their development prospects, while the third cluster of cities is distinguished by a profile that combines opportunities for growth and critical aspects in demographic and economic terms. ----
Le città italiane sono state toccate da due importanti eventi, la crisi del 2008 e del 2012 e la pandemia Covid- 19 nel corso del 2020 e 2021. La ricerca ha l’obiettivo di verificare se, e in quale modo, le città italiane hanno intrapreso un percorso di trasformazione, delineando le loro possibili traiettorie di cambiamento nel decennio intercorso. Le città considerate sono state le città metropolitane cui il legislatore ha attribuito il ruolo di riferimento territoriale per ambiti di carattere regionale. La ricerca ha esaminato i valori del mercato immobiliare per la loro capacità di rappresentare in forma sintetica il grado di attrattività di una città. Le altre variabili impiegate hanno permesso di rilevare l’andamento dei determinanti del mercato immobiliare: crescita economica, sviluppo demografico e variazione nella dotazione di capitale territoriale. Rispetto agli obiettivi della ricerca, la cluster analysis è apparsa lo strumento maggiormente idoneo a rappresentare i cambiamenti aggregando le città secondo pattern comuni. L’indagine ha considerato le reazioni delle diverse città nei due quinquenni legati a ciascun shock esogeno e, complessivamente, nel decennio in esame per una lettura di lungo periodo delle tendenze in atto. Le conclusioni cui perviene l’indagine evidenziano come tra il 2012 e il 2017, vi sia un percorso di concentrazione della ricchezza e della popolazione nei centri maggiori e in particolare nella città di Milano, contraddistinta da valori immobiliari in crescita a fronte di un declino generalizzato del mercato italiano. Nel secondo quinquennio dal 2017 al 2022, lo schema si riproduce con analoga intensità, a dispetto di un vasto dibattito sulla crisi delle grandi città e sulla loro sostenibilità alla prova della pande- mia. Una visione complessiva decennale dal 2012 al 2022 delle città metropolitane evidenzia tendenze do- tate di un carattere sufficientemente solido e stabile. Al caso di Milano, espressione di un processo di concentrazione chiaro e netto su cui la pandemia non ha avuto effetti, fa riscontro un secondo cluster di città metropolitane periferiche che scontano processi che ne penalizzano le prospettive di sviluppo, mentre un terzo cluster di città si distingue per un profilo che unisce opportunità di crescita e aspetti critici sotto il profilo demografico ed economico
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Bioinformatics Goes Viral: I. Databases, Phylogenetics and Phylodynamics Tools for Boosting Virus Research
No full textComputer-aided analysis of proteins or nucleic acids seems like a matter of course nowadays; however, the history of Bioinformatics and Computational Biology is quite recent. The advent of high-throughput sequencing has led to the production of “big data”, which has also affected the field of virology. The collaboration between the communities of bioinformaticians and virologists already started a few decades ago and it was strongly enhanced by the recent SARS-CoV-2 pandemics. In this article, which is the first in a series on how bioinformatics can enhance virus research, we show that highly useful information is retrievable from selected general and dedicated databases. Indeed, an enormous amount of information—both in terms of nucleotide/protein sequences and their annotation—is deposited in the general databases of international organisations participating in the International Nucleotide Sequence Database Collaboration (INSDC). However, more and more virus-specific databases have been established and are progressively enriched with the contents and features reported in this article. Since viruses are intracellular obligate parasites, a special focus is given to host-pathogen protein-protein interaction databases. Finally, we illustrate several phylogenetic and phylodynamic tools, combining information on algorithms and features with practical information on how to use them and case studies that validate their usefulness. Databases and tools for functional inference will be covered in the next article of this series: Bioinformatics goes viral: II. Sequence-based and structure-based functional analyses for boosting virus research
PHOTOSYNTHETIC MEMBRANES .23. DEGRADATION OF SOME CHLOROALIPHATIC WATER CONTAMINANTS BY PHOTOCATALYTIC MEMBRANES IMMOBILIZING TITANIUM-DIOXIDE
No full textThe TiO2-mediated photodegradation of chloroethanoic acid, trichloroethene and tetrachloroethene, chosen as model molecules of aliphatic chloro-organics was studied at 303 +/- 2 K by employing polymeric membranes photografted on cellulose to immobilize the TiO2 (3.0-5.6 mg cm-2). The radiant flux in the absorption range and the volume-surface ratio in the photoreactor cell were kept constant at 2.5 +/- 0.2 mW cm-2 and 1.1 +/- 0.1 mL cm-2 respectively. The initial rate of photodegradation was studied as a function of the initial concentration of reactants by the linearized form of the Langmuir-Hinshelwood equation, by which rate constants k and equilibrium adsorption constants K were evaluated. Values of k (5.7 +/- 0.5-mu-mol h-1) are independent of the chemical nature of the three reactants investigated, in agreement with other literature findings. Values of K are compared with those measured in aqueous suspensions of TiO2 with the same chloro-organics and with the values predicted by a mechanism involving hydroxyl radicals as the primary oxidant adsorbed on the photocatalyst surface. Satisfactory performance and potential technological advantages of photocatalytic membranes are discussed
- …
