Search results for "plastic"
showing 10 items of 7296 documents
Rol de les xarxes perineuronals en la plasticitat d'interneurones de l'escorça cerebral adulta
2018
L’esquizofrènia és un trastorn psiquiàtric complex que afecta a aproximadament el 1% de la població mundial. Tot i que els mecanismes etiopatològics exactes romanen sense esclarir, un recent cos d’evidències apunta a la possible implicació de les xarxes perineuronals, uns agregats especialitzats de la matriu extracel·lular presents en el neocòrtex de mamífers. La formació de les xarxes perineuronals durant el desenvolupament postnatal, el seu possible paper en el control de la plasticitat sinàptica i la seva co-localització amb diferents poblacions neuronals GABAèrgiques que expressen parvalbúmina, suggereixen que l’alteració d’aquestes estructures podria trencar el balanç d’excitació/inhib…
Plasticity
2020
Although the expression πλαστική τέχνη [plastic art] has Greek origins, the derivative term “plasticity” enters the European languages only in the Modern Age. The term has a double meaning: it indicates, at the same time, the art of manipulating a ductile substance and the ability to transform oneself to recreate formal qualities in response to external events (positive meaning of plasticity) or to cancel pre-existing formal configurations, originating morphological novelties (negative meaning of plasticity). For this reason, the birthplace of plasticity is the domain of art but the term is used with different connotations also in the morphological, physicochemical and medical fields.
Accidenti plastici. Quando la plasticità distruttrice crea nuove identità formali
2019
In conseguenza di gravi traumi, talvolta per un nonnulla, la storia di ognuno di noi può subire un radicale cambiamento: la vita che avevamo progettato per anni è costretta a una deviazione improvvisa e irreversibile. Dal trauma sorge una personalità nuova, senza precedenti. Una personalità nata da un incidente, nata per accidente. Il fortuito diviene così sostanziale e l’inaspettato s’inscrive nel nucleo può profondo del nostro essere. Affrontando con delicatezza il tema dell’impatto che i traumi psicofisici possono avere sulla nostra vita, Catherine Malabou intraprende un’avventura filosofica e letteraria in cui Spinoza, Deleuze e Freud incrociano Ovidio, Kafka, Proust e Duras disegnando …
Facile and efficient chemical functionalization of aliphatic polyesters by cross metathesis
2016
International audience; An effective preparation of new tailor-made macromolecular materials via a combination of two (atom-efficient) catalytic transformations is reported. First, new aliphatic polyesters with alternated composition have been prepared using a salen aluminum catalyst system. Next, the pendant vinyl moieties in those copolymers have been selectively transformed into various functional groups by metathesis in the presence of homogeneous Grubbs catalysts. The latter metathesis reaction has been optimized in terms of catalytic activity and selectivity, to define the conditions for an effective and safe procedure that does not affect the macromolecular architecture. All polymer …
Plēsēju smaržas un mehāniskā kairinājuma izraisītā stresa kāpura stadijā ietekme uz Drosophila melanogaster pieaugušo īpatņu ķermeņa oglekļa un slāpe…
2020
Vispārīgā stresa paradigma paredz, ka plēsonības izraisīts stress ietekmē upuru vielmaiņu, to ķermenim liekot noārdīt enerģētiskās rezerves, kas noved pie pastiprinātas slāpekļa savienojumu izdalīšanas vidē. Darbā novērtēta plēsēja smaržas un mehāniskā kairinājuma ietekme kāpura stadijā uz augļu mušu imago fenotipu. Noskaidrots, ka plēsēja smaržas izraisīts stress samazina mušu ķermeņa masu, palielina slāpekļa koncentrāciju un samazina oglekļa un slāpekļa koncentrāciju attiecību. Līdzīgas fenotipa izmaiņas iepriekš novērotas audzējot kāpurus kopā ar dzīvu zirnekli un liecina, ka kāpuru ožai plēsēja atpazīšanā ir būtiskāka nozīme nekā citām maņām. Rezultāti ir pretrunā vispārīgajai stresa pa…
Polypropylene/polyhedral oligomeric silsesquioxane nanocomposites – study of free volumes, crystallinity degree and mass flow rate
2016
Nanokompozyty polipropylen/poliedryczne oligomeryczne silseskwioksany (PP/POSS) przygotowano metodą mieszania w stanie stopionym polimeru. Wpływ struktury oraz ilości zastosowanych nanonapełniaczy POSS na objętości swobodne w polipropylenie określono z zastosowaniem spektroskopii czasów życia pozytonów (PALS). Ustalono zależności pomiędzy parametrami PALS: czasem życia o-Ps (τ3) i natężeniem (I3) składowej o-Ps oraz wartościami stopnia krystaliczności (Xc ) i masowego wskaźnika szybkości płynięcia (MFR) badanych materiałów. Obecność nanonapełniaczy POSS wpłynęła na liczbę i rozmiary objętości swobodnych w polimerze, co spowodowało zmianę mikrostruktury osnowy polipropylenowej. Wraz ze zwięk…
Amphoteric, prevailingly cationic L-arginine polymers of poly(amidoamino acid) structure: Synthesis, acid/base properties and preliminary cytocompati…
2013
A linear amphoteric poly(amidoamino acid), L-ARGO7, is prepared by Michael-type polyaddition of L-arginine with N,N′-methylenebisacrylamide. Chain-extension of acrylamide end-capped L-ARGO7 oligomers with piperazine leads to high-molecular-weight copolymers in which L-arginine maintains its absolute configuration. Acid/base properties of L-ARGO7 polymers show isolectric points of ≈10 and positive net average charges per repeating unit at pH = 7.4 from 0.25 to 0.40. These arginine-rich synthetic polymers possibly share some of the unique biological properties of polyarginine cell-permeating peptides. In vitro tests with mouse embryo fibroblasts balb/3T3 clone A31 show that L-ARGO7 polymers a…
Hetero-difunctional dimers as building blocks for the synthesis of poly(amidoamine)s with hetero-difunctional chain terminals and their derivatives
2012
This article reports on a simple and straightforward preparation method of poly(amidoamine)s (PAAs) with hetero-difunctional chain ends as well as of several up to now hardly obtainable PAA derivatives of biotechnological interest, such as for instance PAAs of controlled molecular weight and narrow polydispersity mono-functionalized at one end with an acrylamide group, PAAs with star-like molecular architecture, graft-PAA-protein conjugates, “tadpole-like” PAA conjugates with hydrophobic moieties able to self assemble into nanoparticles in aqueous media. The key step was to design suitable building blocks consisting of hetero-difunctional dimers (HDDs). In particular, the HDDs considered we…
Acid-Labile Surfactants Based on Poly(ethylene glycol), Carbon Dioxide and Propylene Oxide: Miniemulsion Polymerization and Degradation Studies
2017
Partially degradable, nonionic AB and ABA type di- and triblock copolymers based on poly(propylene carbonate) and poly(ethylene glycol) blocks were synthesized via immortal copolymerization of carbon dioxide and propylene oxide, using mPEG or PEG as a macroinitiator, and (R,R)-(salcy)-CoOBzF5 as a catalyst in a solvent-free one-pot procedure. The amphiphilic surfactants were prepared with molecular weights (Mn) between 2800 and 10,000 g·mol−1 with narrow molecular weight distributions (1.03–1.09). The copolymers were characterized using 1H-, 13C- and DOSY-NMR spectroscopy and size exclusion chromatography (SEC). Surface-active properties were determined by surface tension measurements (crit…
Improvements in Rational Design Strategies of Inulin Derivative Polycation for siRNA Delivery.
2016
The advances of short interfering RNA (siRNA)-mediated therapy provide a powerful option for the treatment of many diseases, including cancer, by silencing the expression of targeted genes involved in the progression of the pathology. On this regard, a new pH-responsive polycation derived from inulin, Inulin-g-imidazole-g-diethylenetriamine (INU-IMI-DETA), was designed and employed to produce INU-IMI-DETA/siRNA "Inulin COmplex Nanoaggregates" (ICONs). The experimental results showed that INU-IMI-DETA exhibited strong cationic characteristics and high solubility in the pH range 3-5 and self-aggregation triggered by pH increase and physiological salt concentration. INU-IMI-DETA showed as well…