267 research outputs found
Modificazioni stagionali dell'ultra struttura della ghiandola androgenica del gambero Aristaeomorpha foliacea
No full textIl colore della scagliola: casi studio di realizzazione e restauri dei “cristalli di gesso”
No full textIl contributo intende soffermarsi sull’antica tecnica della scagliola, variamente definita dalle fonti, tra l’altro,
come mistura, meschia, pasta di marmo, pietra di luna, gesso Atlante, vetro di olaria, pietra speculare,
cristallo di gesso, ma anche vetro di Maria, specchio d’asino, Bossi work e Stuckmarmor, presentando alcuni
esempi dell’esito della lavorazione che ancora oggi avviene in alcune botteghe italiane di alto artigianato. Le
scagliole, nate per simulare le tarsie marmoree, sono state in alcuni casi utilizzate anche per restituire la
percezione di una raffinata “pittura sotto vetro” e le maestranze attive nella Penisola sono state sempre un
punto di riferimento imprescindibile. L’approccio proposto in questo contributo a più mani è
multidisciplinare. Dopo una prima introduzione storica, dedicata in particolare alle localizzazioni delle
principali botteghe e alla diffusione di questa antica arte, si intende soffermarsi sulla complessa tecnica
esecutiva della scagliola attualmente praticata da pochissimi maestri e sull’analisi fisico chimica del degrado
dei materiali. Si intendono illustrare inoltre alcuni esiti inediti di recenti cantieri di restauro a livello
internazionale dove l’antica sapienza della “pietra speculare” ha permesso di ricostruire non soltanto
elementi quali paliotti ma anche apparati decorativi di grandi dimensioni, nell’auspicio di tramandare i colori
della scagliola ai posteri.
XVIII COLOR CONFERENCE - LECCO 2023
6
Paper n° 9340
[9340] Conservare l’effimero: il colore dei “Madonnari”
Paola Artoni (Indipendent Research), Paolo Bertelli (Università Ca' Foscari Venezia), Mariano Bottoli
(Indipendent Researcher), Giulio Pojana (Università Ca' Foscari Venezia), Dafne Cimino (Università di Verona),
Maria Labate (Università di Torino), Maurizio Aceto (Università del Piemonte Orientale) and Angelo Agostino
(Università di Torino).
Si definisce arte madonnara quella particolare espressione della street art caratterizzata dalla realizzazione
di temi sacri cristiani e dall’utilizzo di materiali effimeri, ovvero non destinati a durare nel tempo. Il più antico
festival di arte madonnara al mondo è stato ideato cinquant’anni fa, nel 1973, a Grazie di Curtatone, e da
allora questo piccolo borgo alle porte di Mantova è riconosciuto come la patria dei madonnari di tutto il
mondo. Qui è anche presente un museo dedicato alla conservazione e valorizzazione di questa arte. Potrebbe
sembrare una contraddizione in termini la “conservazione” di un’arte “effimera”, per sua stessa natura
destinata a non durare. Gli artisti solitamente dipingono su un supporto di asfalto, bituminoso, granuloso e
molto ruvido al tatto e utilizzano talvolta una preparazione a base di pigmento in polvere. Il disegno viene
tracciato con delle sanguigne, dei carboncini o dei pastelli di colore bruno, dopodiché si procede alla stesura
del colore. I madonnari utilizzano sia i pastelli in commercio sia i “gessetti” realizzati artigianalmente con una
ricetta-base nella quale la cera d’api e la gomma vengono emulsionate e miscelate con i pigmenti in polvere,
in modo da ottenere una vasta gamma cromatica. In passato nell’area gardesana venivano anche utilizzate
delle terre colorate e dei sassi recuperati in situ. Questa “archeologia madonnara” è stata riproposta in anni
più recenti dal Maestro madonnaro Mariano Bottoli. Le tecniche pittoriche dell’arte madonnara sono talvolta
riproposte su altri supporti, quali le tavolette preparate con tecniche che simulano la terra battuta (supporto
utilizzato dai madonnari prima dell’avvento del bitume), i pannelli in pasta di legno o le tende in fibra
sintetica, in modo da potere conservare questi dipinti nel tempo. La proposta di contributo intende valutare
le caratteristiche del colore dei madonnari da diversi punti di vista. A partire dalle vicende storiche legate alla
nascita di questa arte all’utilizzo dei colori simbolici connessi con la tradizione figurativa sacra cristiana
promossa dalla Chiesa; passando per l’esame delle tecniche artistiche e dei materiali utilizzati. In particolare,
per la prima volta, si propone anche una caratterizzazione strutturale che metta a confronto i diversi tipi di
pastelli e gessetti utilizzati dai madonnari, sia prodotti commerciali sia pastelli fabbricati dagli stessi artisti. In
aggiunta è previsto un primo approccio allo studio dell’invecchiamento dei materiali pittorici, con prospettive
utili alla conservazione dei manufatti e ad eventuali interventi di manutenzione e restauro
A histochemical and ultrastructural study of oogenesis of Aristaeomorpha foliacea (Risso, 1827)
No full textOvaries from mature giant red shrimp Aristaeomorpha foliacea were investigated histochemically and ultrastructurally.
Four growing stages of the oocytes were distinguished: premeiosis stage, previtellogenetic stage, early
vitellogenic stage and late vitellogenic stage. In addition, occasional resorptive oocytes were found. Oogonia and
premeiotic oocytes were found in germinative zones. Previtellogenic and vitellogenic oocytes were localized in
maturative zones. As vitellogenesis proceeded, oocytes showed a progressive development in the number of lipid
droplets as well as in the extension of RER, constituted of dilated cisternae, uniformely scattered throughout the
cytoplasm. The RER produced yolk granules and a lampbrush-like substance. The latter was released under the oolemma
and constituted a characteristic cortical zone. The oolemma did not develop microvilli or micropinocytotic
vesicles to incorporate yolk precursors. Thus, the protein yolk appeared to be of endogenous origin. Few somatic
cells were found around the oocytes, but they never gave place to a continuous epithelial layer around oocytes, thus
it is not possible to speak of ovarian follicle. The cytoplasm of these mesodermal-oocyte associated cells (MOAC)
was characterized by a typical steroidogenic apparatus. Few resorptive immature oocytes were found inside late
vitellogenic oocytes. Since the ovaries were packed with late vitellogenic oocytes and the few immature oocytes
were hardly detectable, oocyte maturation occurred in a synchronous way
An ultrastructural and histochemical study of the germinal cells contained in hemispermatophores of males of the Aristaeomorpha foliacea (Risso, 1827)
No full textThe ultrastructure and the oligosaccharide sequence of glycoconjugates of spermatozoa contained in the
hemispermatophores of males Aristaeomorpha foliacea collected during the main mating and reproductive
periods have been investigated. The hemispermatophores from eleven specimens were packed with typical
round-shaped spermatozoa (max ø 3.8±0.03 lm), characterised by an electron-lucent nucleus not separated
by the nuclear envelope from the thin electron-dense peripheral band of the cytoplasm containing
small vesicles and large mitochondria. Hemispermatophores from two out of eight specimens collected in
April contained few typical spermatozoa, whereas they were filled with roundish large germinal cells (max ø
5.74±0.16 lm) showing a filamentous chromatin in the nuclear region and the cytoplasm rim rich in large
vesicles and myelin-like bodies. These cells were considered as non-mature germ cells, and consequently we
defined their hemispermatophores as ‘‘immature’’. The lectin histochemistry showed differences in the
glycoconjugate composition between germ cells contained in immature hemispermatophores and spermatozoa.
The former had N-linked oligosaccharides containing a-D-Man and internal b-D-GlcNAc (Con A
and KOH-sialidase-WGA affinity) as well as terminal NeuAca2,6Gal/GalNAc and NeuAca2,3Galb1,
4-GlcNAc (SNA and MAA binding). Spermatozoa from mature hemispermatophores also displayed Olinked
oligosaccharides which terminated with b-D-Gal(1–3)-GalNAc dimer (PNA binding) and aGalNAc
(HPA reactivity) in the cytoplasm and with sialic acid linked to b-D-Gal(1–3)-GalNAc (KOH-sialidase-
PNA procedure) in the nucleus. The extracellular matrix in immature hemispermatophores displayed both
N- and O-linked glycoconjugates, whereas it contained only O-linked oligosaccharides in mature ones.
Although the number of specimens examined is low, this study should indicate that the presence of
hemispermatophores in the terminal ampullae of male A. foliacea and of joined hemipetasmas is not
synonymous with maturity
Familial mesial temporal lobe epilepsies: Clinical and genetic features
No full textFamilial mesial temporal lobe epilepsy (FMTLE) was first described as a benign syndrome with prominent psychic and autonomic seizures and no association with hippocampal sclerosis (HS) or febrile seizures (FS). Better definition of the syndrome allowed identification of more heterogeneous phenotypes with mild to severe epileptic disorders, and a variable association with HS and FS. The genetics of these conditions is largely unknown and the hope for the future is that the identification of FMTLE genes will lead to more appropriate approaches for the diagnosis and treatment of TLE
Correction to: Brivaracetam use in clinical practice: a Delphi consensus on its role as first add‐on therapy in focal epilepsy and beyond
No full textThe original article contains an error. In the Consensus Collaborators Group, author name has been inverted during the publication. Family name was captured first instead of the given name. The corrected names as follows: Consensus Collaborators Group: Daniela Audenino, Giovanni Boero, Vittoria Cianci, Mario Coletti Moja, Eduardo Cumbo, Filippo Dainese, Giuseppe Didato, Elisa Fallica, Alfonso Giordano, Emilio Le Piane, Mariangela Panebianco, Marta Piccioli, Pietro Pignatta, Monica Puligheddu, Patrizia Pulitano, Federica Ranzato, Rosaria Renna, Eleonora Rosati, Stella Vergine. The original article has been corrected
Multi-Analytical and Non-Invasive Approach for Characterising Blackened Areas of Originally Blue Paints
No full textAzurite, a natural mineral pigment consisting of basic copper carbonate (2CuCO3·Cu(OH)2), is one of the Middle Ages’ most common blue pigments. Why paintings originally coated with azurite appear blackened today remains debated. Using a non-invasive multi-analytical approach, the study analysed several unexpectedly black-appearing details (objects such as books or clothing such as veils, robes, or mantles) in Antoine de Lonhy’s works. The aim was to investigate if the black colour was due to intentional iconographic reasons, incautious restoration work, or painting deterioration. The analytical results displayed the presence of the blue pigment azurite, therefore, the expected original colour of various areas should be blue. To shed light on the discussion regarding the blackening, several other Renaissance paintings with similar black details were analysed, all from the same period and geographic area as de Lonhy’s works and conserved under identical conditions. The reasons why the blackening takes place are still unclear. However, the combined use of X-ray fluorescence spectrometry (XRF), UV-visible diffuse reflectance spectrophotometry with optical fibres (FORS), portable X-ray diffraction (XRD), and the elemental mapping based on the XRF data revealed that these blackened areas were originally painted with azurite, suggesting they were once blue. This finding significantly changes the overall appreciation of these artworks
AMPA receptors and perampanel behind selected epilepsies: current evidence and future perspectives
No full textThe alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptors are the major mediators of glutamate-mediated excitatory neurotransmission, and are critical for synchronization and spread of epileptic activity. Areas covered: AMPA receptor antagonists have been also developed as antiepileptic drugs and perampanel (PER) is the first highly selective, non-competitive AMPA-type glutamate receptor antagonist that is available on the market. It is approved as adjunctive therapy for the treatment of partial-onset seizures with or without secondary generalization, and for primary generalized tonic-clonic seizures in idiopathic generalized epilepsy, in patients aged ≥ 12 years. This article reviews the role of AMPA receptors in the neuronal hyperexcitability underlying epilepsy, the mechanism of action and clinical experience on the anti-seizure activity of PER. Moreover, the rationale for targeting AMPA receptor in specific epileptic disorders, including brain tumor-related epilepsy, mesial temporal lobe epilepsy with/without hippocampal sclerosis, and status epilepticus is evaluated. Finally, the pharmacological rationale for the development of AMPA receptor antagonists in other neurological disorders beyond epilepsy is considered. Expert opinion: Further research aimed at better understanding the pharmacology and blocking mechanism of PER and other AMPA receptor antagonists will drive future development of therapeutic agents that target epilepsy and other neurological diseases
Unusual Composition of the Sarezzano Reliquary Busts
No full textThe interdisciplinary study of two reliquary busts from Sarezzano (Piedmont, Italy) is a perfect example of the necessity to provide for material characterisation as a recurring common practice in historical studies and a mandatory step in conservation assessment. Furthermore, the diagnostics of cultural heritage play a crucial role in art historical research, providing relevant information on artefacts’ genesis, production technology, and conservation history. The study of the materials of the reliquary busts was performed by non-invasive (portable X-ray fluorescence spectrometry) and micro-invasive (stereomicroscope, attenuated total reflection Fourier transform infrared spectroscopy and powder X-ray diffraction analysis) methods. According to the results, the busts were found to be made of a tin–lead alloy, a rather unusual material for mediaeval reliquary busts. Moreover, the outcome suggests that the busts were originally silvered, except for the hair and beard which are still gilded. The analysis reveals the use of colophony as an adhesive buffer layer on the busts’ alloy, as well as inside them, to favour the metal working process, since it is found as degraded residue. Finally, even the typology of alloy decay is defined. All this information has enabled us to determine the artistic technique and estimate the value and quality of the material employed. In addition, it has led to the correct choice of materials and methods to be adopted during the restoration, and therefore the usage of more suitable solvents and tools
- …
