Long-living optical gain induced by solvent viscosity in a push-pull molecule.

The combination of continuum and ultrafast pump-probe spectroscopy with DFT and TDDFT calculations, in viscous and non-viscous environments, is effective in unraveling important features of the twisted intramolecular charge transfer mechanism in a new push-pull molecule that possesses aggregation induced emission properties. Long-living optical gain is found when this mechanism is inhibited, highlighting the importance of the environment rigidity in the design of materials for photonic applications.

Photo-Physical Behaviour of CdSe Nanocrystals/Bis(dithiocarbamate) Linker Multilayered Hybrid Systems.

Multilayered films composed by CdSe Nanocrystals (NCs) interlinked by ethylene-1,2-bis(dithiocarbamate) or adipate anions were prepared on ITO glass via layer-by-layer alternation. The films were analyzed by UV-vis, TEM, Photoluminescence (PL) emission and Pump-Probe spectroscopy. While the PL emission of the two samples present no differences, femtosecond Pump-probe experiments reveal an higher charge generation efficiency in bis(dithiocarbamate) based films than in dicarboxylate ones.

Optical gain from polyfluorene keto defects in a liquid crystal mixture.

By means of confocal photoluminescence measurements and fs pump-probe spectroscopy, we observe the optical properties of phase separation in a mixture of polyfluorene and Liquid Crystals (LCs). The boundaries of LC-rich micro-domains display a large polarized gain region from keto defects stemming from the single-chain nature of this defect.

The elongation of the internal carotid artery. Diagnosis and surgical treatment.

Cerebro-vascular insufficiency is rarely caused by an abnormal elongation of the internal carotid artery (the ratio is 15% to 17% of symptomatic patients). The anomalies can be defined as: tortuosity, when the artery has a "C" or "S" shape; coiling, when the elongation is more evident and the artery forms one or more loops; kinking, when there is a sharp angulation of the first portion of the internal carotid artery. The etiology of these peculiar arterial modifications seems to be related to a congenital basis which may become exaggerated with ageing of the artery. Surgical correction should include intra-arterial inspection (TEA) as well as eliminating the pathological elongation. The Authors presents their 9 cases surgical experience.

Immunoscintigraphic localization in a benign thyroid neoplasm of a monoclonal antibody directed against melanoma.

In a prospective study for evaluation of the use of a monoclonal antibody directed against melanoma in the staging of patients affected by malignant melanoma, we report monoclonal antibody uptake in a follicular thyroid adenoma. Computed tomography, ultrasonography, and pertechnetate scintigraphy did not provide a certain diagnosis. Only pathologic examination of the surgical specimen was conclusive.

[Isthmic coarctation of the aorta. Description of an anomalous case]. / Coartazione istmica dell'aorta. Descrizione di un caso anomalo.

An anomalous (because of the advanced age of its onset) case of isthmic coarctation of the aorta in preductal site observed at the persistence of hypertensive symptomatology associated with cephalgic and lipothymic attacks is reported. Instrumental examinations confirmed the clinical suspicion and resective-reconstructive surgical treatment led to complete resolution of both cause and effect.

[Retroesophageal right subclavian artery. Description of a clinical case]. / Arteria succlavia destra retroesofagea. Descrizione di un caso clinico.

A case of retroesophageal right subclavian artery, occasionally observed in a patient submitted to diagnostic investigation and surgical treatment for bilateral steno-obstructive involvement of the carotid district, is described.

[Importance of intraoperative H/R ultrasonography in the immediate evaluation of the results of thromboendarterectomy of the carotid bifurcation]. / Importanza dell'ecografia H/R intraoperatoria nella valutazione immediata del risultato degli interventi di TEA della biforcazione carotidea.

Personal experience on the intraoperative use of HR echography for the evaluation of the immediate surgical results in carotid bifurcation T.E.A. is reported. It is already assessed that early failure in vascular surgery is due to technically incorrect procedures.

[Acute abdomen secondary to autoimmune vasculitis in systemic lupus erythematosus. Case report]. / Addome acuto da vasculite autoimmune in corso di lupus eritematoso sistemico. Descrizione di un caso clinico.

The authors report the case of a female patient suffering from systemic lupus erythematosus who was referred to their attention with symptoms of acute abdomen due to gangrenous appendicitis following autoimmune vasculitis.

[Mechanical staplers in colorectal surgery: cost-benefit ratio]. / Le suturatrici meccaniche in chirurgia colo-rettale: rapporto costi/benefìci.

The cost/benefit ratio of stapled anastomoses in colorectal surgery has been retrospectively evaluated on the basis of a 8 year experience taking into account the overall costs in surgery as well as short term and long term benefits. With this aim, our experience was divided in two periods: 1st period: November 1970-January 1981: 598 hand sutures; 2nd period: February 1981-December 1988: 787 stapled sutures. Mechanical suturing was found to be superior based on the following: a) the average postoperative hospital stay decreased from 20.2 days to 14.7 days; b) temporary stomas decreased from 62.2 to 25.1%; c) abdominoperineal resection for rectal cancer decreased from 60.7 to 41.6%.

Photoinduced transient stark spectroscopy in organic semiconductors: a method for charge mobility determination in the picosecond regime.

Subpicosecond photoinduced Stark spectroscopy experiments are carried out for measuring charge carrier mobility in organic semiconductors. The technique is demonstrated in state-of-art devices based on methanofullerene. The transient mobility of photogenerated charge carriers is measured in the picosecond time domain. Electric field dependent mobility is observed from the earliest time scales. In addition, two distinct transport regimes are revealed: a short-lived state, approximately 10 ps, of high mobility and a transient towards the trap limited transport, associated with the mesoscopic structure of the medium.

Ultrafast intrachain photoexcitation of polymeric semiconductors.

We report on excited state dynamics in isolated poly(9,9-dioctylfluorene) chains obtained by embedding the polymer in an inert plastic matrix. Early events (<300 fs) of intrachain photophysics are detected by pump-probe spectroscopy using tunable UV 25-fs pump pulses and sub-10-fs visible probe pulses. We show that higher-lying optical states, reached by multiphoton transitions, give rise to on-chain charge separation on the ultrafast time scale. The intrachain charge pair decays geminately within 500 fs to the lowest singlet state. Characteristic time scales for internal conversion and intramolecular vibrational redistribution are also determined.

Understanding fundamental processes in poly(9,9-dioctylfluorene) light-emitting diodes via ultrafast electric-field-assisted pump-probe spectroscopy.

Femtosecond electric-field-assisted pump-probe measurements are a new approach to the study of fundamental processes within organic optoelectronic devices. Here we report a detailed study of organic light-emitting diodes based on poly(9,9-dioctylfluorene), using both temporal and spectral information to investigate polaron generation, due to field-induced singlet dissociation, and their subsequent recombination. The fundamental event in electroluminescence is time resolved: we find that initially free polarons coalesce into intermediate pairs of both singlets and triplets multiplicity which subsequently decay into the neutral state. Our results indicate that the efficiency of singlet formation, beta approximately 0.7, is much higher than expected from simple state degeneracy arguments (beta approximately 0.25).