Tuning of the luminescence in poly((silanylene)thiophene)s

Synthetic routes to alternating copolymers consisting of oligosilylene blocks and oligothiophene blocks (T-x; x = 1, 2, 3, 4, or 6 rings) are presented. Solubility requirements for obtaining acceptable molecular weights and, eventually, for film formation are met by the introduction of butyl groups replacing methyls on the silicon atoms and by employing T-6 blocks carrying two octyl substituents. Additionally, substituted oligothiophenes are synthesized as an aid in the interpretation of NMR, absorption, and fluorescence spectra. Regarding the electronic configuration of the oligothiophene blocks, NMR spectra show clear differences between plain oligothiophenes, end-substituted oligothiophenes, and polymers, indicative of pi-sigma interactions with the oligosilylene blocks and possible through-conjugation to adjacent blocks in polymers. Red shifts in optical spectra show a parallel trend across the various compounds based on the same oligothiophene unit, related to the stabilization of photoexcited states on the oligothiophene by the oligosilylene substituents. These effects are strong in T-2-based compounds and reduced fdr longer T-n. The main feature of the spectra is the decrease of the transition energies with the size of the oligothiophene blocks in the polymers. Since this effect is also found in fluorescence, it enables one to adjust the luminescence wavelength by choosing the proper block length (''chemical tuning''). Fluorescence quantum efficiencies in solution are found to be remarkably high in polymers based on T-2 blocks. Spin-coated films of T-2-based (or T-3-based) polymers show evidence of T-4 (T-6) impurity blocks that act as an exciton trap

Charge injection across a polymeric heterojunction

The charge injection across a polymeric heterojunction of a poly-p-phenylene vinylene derivative (injecting layer) and poly (9,9-dioctylfluorene) (accepting layer) is investigated. The electric field in the accepting layer is obtained after correcting the applied voltage for the voltage drop across the injecting layer due to the buildup of space charge. At high electric fields, the current across the polymeric heterojunction exhibits only a weak dependence on the field due to the absence of image force effects, in agreement with model predictions. The strong dependence at low fields can be explained by taking the increase of the Fermi level into account, which effectively modifies the barrier for charge carriers waiting for a jump across the heterojunction

Improved Synthesis of 2,6,6-trimethyl-1-cyclohexene-1-acetaldehyde, a Key Intermediate for Drimane-related Sesquiterpenes.

The titel compound is conveniently prepared in 65% overall yield by a two step synthesis starting from he commercially available β-ionone

LEDs based on conjugated PPV block copolymers

A way to control the bandgap in semi-conducting polymers is by preparing polymers with a partially conjugated backbone. In our laboratory, three conjugated copolymers containing PPV trimers as light emitting chromophores have been synthesized, which emit in the blue, green and orange wavelength region. The copolymers have a well defined conjugated backbone consisting of regularly alternating terphenylene and p-phenylene-vinylene blocks. The desired control of conjugation length is achieved through steric interaction induced by the side-chains in the terphenyl blocks of the copolymer. In this paper we evaluate the electrical and optical properties of LED devices based on these conjugated PPV block copolymers

Autismo in famiglia: quali i tratti in comune? Un contributo di ricerca nell'ambito del Broader Autism Phenotype

Background. L’espressione Broader Autism Phenotype (BAP), la cui versione italiana è “fenotipo autistico ampio”, descrive una condizione subclinica, indagata a partire dagli anni 70 sia in ambito genetico che psicologico, nella quale si collocano soggetti , e soprattutto parenti di primo grado di soggetti con autismo, che presentano tratti riconducibili ai tratti peculiari e ai domini dei Disturbi dello Spettro Autistico (ASD). La maggior parte delle ricerche ha mostrato, mediante Studi Familiari e l’uso di Scale Psicometriche, come questi tratti siano maggiormente presenti nei genitori di soggetti nello Spettro autistico rispetto alla popolazione generale. Pochi risultano dalla letteratura i contributi di ricerca nei quali sono stati analizzati i tratti maggiormente condivisi da genitori e figli ASD. Obiettivi. l’obiettivo principale della nostra ricerca sperimentale è stato valutare, in un campione di 131 genitori italiani di 68 bambini con Disturbo dello Spettro Autistico (ASD), le correlazioni tra i tratti dei genitori misurati con l’AQ e i tratti autistici e le variabili cliniche dei figli misurate rispettivamente mediante l’AQ-child e il protocollo diagnostico. Risultati. Sono stati evidenziati tratti comuni soprattutto tra padri e figli e in particolare nella sfera sociale e comunicativa. Si evince un rapporto di correlazione positivo tra numero di tratti autistici nei padri e tratti autistici nei figli. Alcuni tratti dei padri correlano con il comportamento adattivo dei figli misurato con la scala Vineland . Tra i genitori che hanno superato i criteri soglia per il BAP, sono emersi tratti in comune solo tra le madri e i figli. In particolare a una maggiore o minore tendenza all’elaborazione locale degli stimoli nelle madri corrisponde una maggiore o minore tendenza anche nei figli. L’età della madre correla con la gravità della sintomatologia autistica nei figli misurata con l’ADOS. Dallo studio non è emersa una relazione positiva e significativa tra maggiori tratti autistici nei genitori e gravità della sintomatologia autistica nei figli. Conclusioni. valutare i tratti comuni tra genitori e figli ASD permette di comprendere le modalità di trasmissione dei tratti BAP a livello intergenerazionale e permette di verificare i tratti dei genitori che possono costituire fattori di rischio o protezione all’ASD dei figli. Può inoltre risultare utile nella formulazione di programmi di Parent Coaching più adeguati alle caratteristiche del genitore

Practical reflections on combining workshops and mentorships to build capacity in demand and use of evidence in government organisations

Decision makers’ capacity to use evidence is a key component of evidence-informed decision making (EIDM) at a policy level. This paper describes a unique combination of EIDM workshops and mentoring to build decision makers’ capacity to use evidence. It reflects how the deliberate design of sequential workshop and mentoring capacity-building activities enhanced programme effects and reports on the design features that we believe have most contributed to the observed effects. We have found that this combined approach is most effective when it is underpinned by a relationship-building theory of change and remains flexible and responsive to delivering on the needs of participants, and when it is delivered in a timely manner by partners who have been carefully paired with participants based on required expertise