30,070 research outputs found
"Or vos conterons d'autre matiere". Studi di filologia romanza offerti a Gabriella Ronchi
No full textQuesta raccolta di saggi di filologia romanza offerta a Gabriella Ronchi da amici e allievi contiene studi su testi e autori di cui la dedicataria della miscellanea si è occupata (il Milione, il Tristano di Béroul, volgarizzamenti, Ariosto), ma è aperta a vari generi della produzione medievale (epica, lirica, narrativa breve e allegorica), con particolare attenzione per le aree italiana e gallo-romanza. Le escursioni su temi moderni e contemporanei ampliano la visuale oltre i confini del Medioevo
Sintesi, caratterizzazione strutturale e attività biologica in vitro di organostagno(IV) con derivati di 1,2,4-triazolo[1,5-a]pirimidina
No full textSINTESI, CARATTERIZZAZIONE STRUTTURALE E ATTIVITÀ BIOLOGICA IN VITRO DI ORGANOSTAGNO(IV) CON DERIVATI DI 1,2,4-TRIAZOLO[1, 5-a]PIRIMIDINA
Maria Assunta Girasolo a, Simona Rubino a, Piera Sabatino b
aDip.to di Scienze e Tecnologie Molecolari e Biomolecolari, Università di Palermo, Viale delle Scienze, Palermo, Italy
bDip.to di Chimica G. Ciamician, Università di Bologna,via F. Selmi 2, Bologna, Italy
La struttura delle 1,2,4-triazolo[1,5-a]pirimidine1 è analoga a quella delle purine da cui differiscono per la presenza di un atomo di azoto pirimidinico in posizione “testa di ponte” e la scomparsa del protone acido dell’anello a cinque membri. Data la somiglianza tra questi sistemi, i composti di coordinazione delle 1,2,4-triazolo-[1,5-a]pirimidine possono essere considerati come sistemi modello per vari composti di coordinazione esistenti in natura. Recentemente sono stati sintetizzati e caratterizzati alcuni composti di diorganostagno(IV) con 5,7-diphenyl-1,2,4-triazolo[1,5-a]pyrimidine2 (dptp), di cui viene qui riportata la struttura ai raggi X, e con l’acido 7-ammino-2-(metiltio)-[1,2,4]triazolo[1,5-a]pirimidina-6-carbossilico.
Figura 1: Struttura cristallina e molecolare dell’addotto [n-Bu2SnCl2(dptp)] (1)
Il composto (1) presenta una coordinazione bipiramidale trigonale distorta intorno all’atomo di Sn; il legante dptp, che lega tramite N(3), occupa la posizione trans rispetto ad uno dei due atomi di Cl mentre le tre posizioni equatoriali sono occupate dal rimanente atomo di Cl e dai due leganti n-butilici. L’impaccamento tridimensionale della molecola è caratterizzato sia da un network di legami a H tra i gruppi C-H e gli atomi di Cl sia da interazioni aromatiche tra gli anelli aromatici presenti. L’attività citotossica di (1) è stata testata sulla linea cellulare umana U937 di linfoma istiocitico. Le cellule sono state trattate per 24 h in un range di concentrazioni compreso tra 0.5-20 μM dell’addotto (1), in comparazione al cisplatino. I risultati ottenuti hanno dimostrato che alla concentrazione di 20 μM, n-Bu2SnCl2(dptp) induce una marcata riduzione della vitalità cellulare che risulta essere del 5.5%, valore molto più basso del cisplatino, che alla stessa concentrazione risulta del 44%. Il composto è quindi più attivo del cisplatino. I complessi R2SnL2 sono stati ottenuti per reazione di R2SnO (R = Me, n-Bu, n-Oct ) con l’acido 7-ammino-2-(metiltio)-[1,2,4]triazolo[1,5-a]pirimidina-6-carbossilico3 (HL) in metanolo a riflusso. La natura dei prodotti ottenuti è stata indagata analizzando i dati spettroscopici 1H-NMR, IR e 119Sn Mössbauer. Esaminando i parametri Mössbauer possiamo osservare che i valori di splitting di quadrupolo sono più grandi dei valori osservati in complessi di diorganostagno(IV) con geometria tetraedrica. Dobbiamo quindi presumere che lo stagno espanda il numero di coordinazione dando luogo a strutture bipiramidali trigonali, cis- o trans-R2, o ottaedriche trans-R2 fortemente distorte.
Bibliografia
1Salas,J.M.;Romero,M.A.;Sánchez,M.P.;Quirós,M.,Coord. Chem. Rev.,1999,1119,193. 2Girasolo,M.A.;Canfora,L.;Sabatino,P.;Schillaci,D.;Foresti,E.;Rubino,S.;Ruisi,G.;Stocco,G., J.Inorg.Biochem.,2012,106,156. 3Ruisi,G.,Canfora,L.;Bruno,G.;Rotondo,A.;Mastropietro, T.F.;Debbia,E.A.;Girasolo,M.A.;Megna,B., J.Organomet. Chem.,2010,695,546
Electrochemical treatment of real wastewater. Part 1: Effluents with low conductivity
No full textThe treatment of a real wastewater characterized by low conductivity was performed by anodic oxidation at boron doped diamond (BDD) in both conventional and microfluidic cells. The electrolyses carried out in conventional cells without supporting electrolyte were characterized by very high TOC removals but excessively high energetic consumptions and operating costs. The addition of sodium sulphate, as supporting electrolyte, allowed to strongly reduce the cell potentials and consequently the energetic consumptions and the operating costs. However, under various operating conditions, the addition of Na2SO4caused a lower removal of the TOC. The best results in terms of both TOC removal, energetic consumptions and operating costs (about 1 â¬/m3) were obtained using a cell with a very low inter-electrode distance (50 Âμm) with no addition of a supporting electrolyte
Reduction of oxygen to H2O2 at carbon felt cathode in undivided cells. Effect of the ratio between the anode and the cathode surfaces and of other operative parameters
No full textIn the last years, the electrochemical conversion of oxygen to hydrogen peroxide at carbon felt has been largely studied in order to define a new route for the production of H2O2 and to optimize the electro-Fenton process, which is based on the cathodic generation of H2O2. In particular, many studies regarding electro-Fenton process were carried out in undivided cells in order to avoid the costs of the separator and to reduce the cell potentials.
Hence, in order to optimize the cathodic conversion of oxygen to H2O2 in undivided cells, the effect of many parameters linked to the anodic process were here evaluated. In particular, it was demonstrated that the performances of the process strongly depends on the ratio between the cathode and the anode surfaces, the nature of the anode, the mixing rate and the current density
Immersioni quotidiane. Vita ordinaria, cultura visuale e nuovi media
No full textIl volume esplora elementi della vita ordinaria contemporanea divenuti ai nostri occhi insieme problematici e sorprendenti – identità, corpi, sensi, luoghi, oggetti, immagini – giacché trasformati senza sosta dalle innovazioni della cultura tecno-estetica e visuale dei nuovi media e dalle applicazioni della realtà virtuale e aumentata al mondo in cui siamo immersi. Approfondendo le tante piccole esperienze e pratiche creative, ma anche critiche, oggi possibili nel nostro quotidiano ipermediato, i curatori del volume privilegiano prospettive e strumenti di lettura apertamente inter-, multi- e trans-disciplinari: dall’estetica all’Everyday Aesthetics, dalle teorie all’archeologia dei media, dai Film ai Game Studies.The volume explores elements of contemporary ordinary contemporary life that have become our eyes both problematic and surprising - identities, bodies, senses
places, objects, images - as they are transformed relentlessly by the innovations
of techno-aesthetic and visual culture of new media and by the applications
of virtual and augmented reality to the world in which we are immersed.
Delving into the many small experiences and creative practices, but also
possible today in our hypermediated everyday life, the editors of the volume
favour openly inter-, multi- and trans-disciplinary perspectives and reading tools: from aesthetics to Everyday Aesthetics, from theories to media archaeology, from Film to Game Studies
Use of Unrooted Grafted Vegetable Cuttings: I. Effects of Healing Duration and Transportation Temperature
No full textogy
to overcome soil-borne diseases and pests and to add extra
vigor to the plants under various environmental stress conditions.
In order to advance the use of grafting in U.S. vegetable production
in open fields, key issues to address include 1) increasing
the propagation capacity to meet the expected large number of
seedlings necessary to supply the demands of typically large
farms and 2) reducing production costs. Traditionally, vegetable
grafting is a labor-intensive process involving much training and
logistics. However, the seasonal nature of nursery operations
due to the limitation of transportation of the grafted seedlings
is problematic when nurseries are interested in introducing
vegetable grafting to serve producers who are interested in using
the technology. To address this issue, we examined factors
affecting quality and growth of unrooted grafted cuttings as a
means to improve the distribution of grafted materials and for
nurseries to centralize the labor-intensive grafting operation to
serve producers in various regions (i.e., various planting seasons).
Grafted tomato and watermelon cuttings (‘Durinta’ tomato or
‘Tri-X 313’ watermelon scion with ‘Aloha’ tomato or ‘Strong
Tosa’ interspecific hybrid squash rootstock’, respectively) were
harvested after 0, 1, 3, 5, or 7 days of healing after grafting and
kept for 72 hours in a dark chamber maintained at 10 (tomato),
12 (watermelon) or 20 °C (both species). The results showed that
it required a minimum of 3 and 5 days of post-grafting healing
for tomato and watermelon, respectively, before harvest in order
to maintain growth and development rates after 3-day simulated
transportation, as equivalent to non-treated cuttings (control).
Transportation at a lower temperature (10 °C for tomato or 12 °C
for watermelon) seems to contribute to maintaining better visual
cutting quality than 20 °C. Although more research needs to
be done to establish protocols suitable for various species and
scion-rootstock combinations, effective use of unrooted grafted
cuttings in nurseries with and without grafting capabilities may
become a breakthrough technology to advance the use of grafted
plants in the United States
The role of water in radiation-induced fragmentation of cellulosic backbone polysaccharides
No full textXyloglucan (XG) is a cellulosic backbone polysaccharide commercially used for food applications, but also widely investigated in biomedical applications, for its gelling properties and specific biological activity. In this study, the possibility of using gamma radiation to cleave XG and generate lower molecular weight variants was explored. The impact of absorbed dose and irradiation conditions on the XG molecular weight distribution was investigated. Two other cellulosic polysaccharides, hydroxypropyl cellulose (HPC) and an oxidized variant of XG (CXG), were also studied for comparison. Before irradiation, the polymers were characterized with thermal gravimetric analysis and, after irradiation, with gel permeation chromatography. The results showed that for XG irradiated in dilute aqueous solution, a dose of 10 Gy is sufficient to significantly reduce the polymer molecular weight, while HPC is less affected by irradiation under identical conditions. When the polymers were irradiated in the solid form, either dry or humid, the reduction in average molecular weight is much less pronounced. Interestingly, for HPC the cleavage of the chains is more pronounced for the dry than for the humid powder. A similar behavior, but less pronounced, was observed for XG and CXG. Arguably, when water was present in the system as bound water it had a protective effect. This is probably due to energy transfer from the polymer to the bound water preventing chain scission. Indeed, humid HPC has more bound water than XG and CXG. Conversely, when water was present as solvent, water radiolysis products were able to efficiently induce depolymerization
Variations on the Author
No full text“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Non-covalent interactions in organotin(IV) derivatives of 5,7-ditertbutyl- and 5,7-diphenyl-1,2,4-triazolo[1,5-a]pyrimidine as recognition motifs in crystalline self- assembly and their in vitro antistaphylococcal activity
No full textNon-covalent interactions are known to play a key role in biological compounds due to their
stabilization of the tertiary and quaternary structure of proteins [1]. Ligands similar to purine rings,
such as triazolo pyrimidine ones, are very versatile in their interactions with metals and can act as
model systems for natural bio-inorganic compounds [2]. A considerable series (twelve novel
compounds are reported) of 5,7-ditertbutyl-1,2,4-triazolo[1,5-a]pyrimidine (dbtp) and 5,7-diphenyl-
1,2,4-triazolo[1,5-a]pyrimidine (dptp) were synthesized and investigated by FT-IR and 119Sn
Mössbauer in the solid state and by 1H and 13C NMR spectroscopy, in solution [3]. The X-ray
crystal and molecular structures of Et2SnCl2(dbtp)2 and Ph2SnCl2(EtOH)2(dptp)2 were described, in
this latter pyrimidine molecules are not directly bound to the metal center but strictly H-bonded,
through N(3), to the -OH group of the ethanol moieties. The network of hydrogen bonding and
aromatic interactions involving pyrimidine and phenyl
rings in both complexes drives their self-assembly. Noncovalent
interactions involving aromatic rings are key
processes in both chemical and biological recognition,
contributing to overall complex stability and forming
recognition motifs. It is noteworthy that in
Ph2SnCl2(EtOH)2(dptp)2 π–π stacking interactions between
pairs of antiparallel triazolopyrimidine rings mimick basepair
interactions physiologically occurring in DNA (Fig.1).
Mössbauer spectra suggest for Et2SnCl2(dbtp)2 a
distorted octahedral structure, with C-Sn-C bond angles
lower than 180°. The estimated angle for Et2SnCl2(dbtp)2
is virtually identical to that determined by X-ray diffraction. Ph2SnCl2(EtOH)2(dptp)2 is
characterized by an essentially linear C-Sn-C fragment according to the X-ray all-trans structure.
The compounds were screened for their in vitro antibacterial activity on a group of reference
staphylococcal strains susceptible or resistant to methicillin and against two reference Gramnegative
pathogens [4] . We tested the biological activity of all the specimen against a group of
staphylococcal reference strains (S. aureus ATCC 25923, S. aureus ATCC 29213, methicillin
resistant S. aureus 43866 and S. epidermidis RP62A) along with Gram-negative pathogens (P.
aeruginosa ATCC9027 and E. coli ATCC25922). Ph2SnCl2(EtOH)2(dptp)2 showed good
antibacterial activity with a MIC value of 5 μg mL-1 against S. aureus ATCC29213 and also
resulted active against methicillin resistant S. epidermidis RP62A
Dielectric Characterization of Biocompatible Hydrogels for Application to Epidermal RFID Device
No full textFunctionalized skin-like membranes are currently under investigation for the design of a new class of Epidermal Electronics devices for sensing and healing applications. The dynamic response of epidermal antennas in presence of absorption and release of fluids is a key-point to design RFID radio-sensors and actuators. This paper addresses the characterization of the dielectric property of PVA-based biocompatible hydrogel membranes in the UHF RFID band by means of a modified ring resonator. Samples having different compositions are measured in the dry state as well as when exposed to a progressive release of body fluids emulating perspirations or wound exudates. It was found that the permittivity increases up to 10 times demonstrating that such membranes may be also used as sensors
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