A multimodal dataset for authoring and editing multimedia content:the MAMEM project

We present a dataset that combines multimodal biosignals and eye tracking information gathered under a human-computer interaction framework. The dataset was developed in the vein of the MAMEM project that aims to endow people with motor disabilities with the ability to edit and author multimedia content through mental commands and gaze activity. The dataset includes EEG, eye-tracking, and physiological (GSR and Heart rate) signals collected from 34 individuals (18 able-bodied and 16 motor-impaired). Data were collected during the interaction with specifically designed interface for web browsing and multimedia content manipulation and during imaginary movement tasks. The presented dataset will contribute towards the development and evaluation of modern human-computer interaction systems that would foster the integration of people with severe motor impairments back into society.</p

Substitution, environment, and excitation wavelength effects on the optical nonlinearities of some novel cis -/trans-\u3c0-conjugated azobenzenes

The transient nonlinear optical response of a series of highly \u3c0-conjugated 4,4\u2032-diethynylazobenzene derivatives, symmetrically substituted with different electron-rich aromatic moieties (i.e., a N,N\u2032-dihexylaniline, 4-ethynyl-(N,N\u2032,dihexylaniline), and a Zn(II)-porphyrin fragment, respectively) is investigated by means of the Z-scan technique. The systematic study of their nonlinear optical properties, using 4 ns laser excitation, revealed that all molecules possess very large third-order nonlinearity excited at 532 nm, whereas only the aniline derivatives showed nonlinear optical (NLO) response under 1064 nm excitation. In-depth investigation, both in solutions and in thin films, established that the NLO response of these azobenzene (AB) derivatives is totally attributed to their high refractive nonlinearity, presenting negligible nonlinear absorption. These findings strongly suggest that these molecules can be exploited for the development of new materials suitable for photonic/optoelectronic devices, since their strong nonlinear refraction combined with the absence of any nonlinear absorption ensures low losses, very low heating of the organic material, and eventually longer operative lifetimes. \ua9 2014 American Chemical Society

NLO response of photoswitchable azobenzene-based materials

The nonlinear optical (NLO) response of three π-conjugated azobenzene (AB) derivatives was investigated under picosecond laser excitation by means of the Z-scan technique to evaluate the effect of an ethynyl-based conjugated spacer on the NLO properties of ABs. All modules possessed large third-order nonlinearity, but unexpectedly it was the less extended AB derivative that exhibited the largest NLO response. This finding has been confirmed by means of DFT calculations and was attributed to a higher cis/trans ratio of the particular AB derivative in its investigated photoequilibrated state. Furthermore, the influence of the amount of cis isomer on the third-order nonlinear susceptibility [χ(3)] of the less extended AB derivative has been thoroughly investigated. Specifically, modulation of the NLO response has been successfully achieved by tuning the isomeric composition of the investigated photostationary state. These results highlighted the cis-dependent increase of the NLO response to support the general idea that such compounds can be used for multistep switching NLO materials. Flick of a switch: The nonlinear optical (NLO) response of three π-conjugated azobenzene (AB) derivatives is investigated to evaluate the effect of an ethynyl-based conjugated spacer on the NLO properties of ABs. A cis-isomer-dependent increase of the NLO response, together with intrinsic structure-related high hyperpolarizability values, determined these compounds superb candidates for ultrafast switching NLO devices. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

The effect of the degree of oxidation on broadband nonlinear absorption and ferromagnetic ordering in graphene oxide

We report on the effect of the degree of oxidation on the broadband non-linear optical response and magnetic behavior of graphene oxide, as well as on a route for obtaining reduced graphene oxide with enhanced optical properties without sacrificing the high dispersibility of the parent graphene oxide. As more sp3 states evolved with the rise in oxidation degree, it turned out that the sp2/sp3 fraction and sp2 clustering are crucial parameters for tuning the broadband non-linear optical absorption over a wide range from ps to ns laser pulses for both visible and infrared laser irradiation. This was clearly confirmed by two different approaches, namely by a synthetic route through the gradual oxidation of graphene oxide from 1 to 3 oxidizing cycles, and reversely by in situ reduction of graphene oxide by UV laser irradiation. Furthermore, as the sp3 states carry localized magnetic moments, ferromagnetic ordering is observed at low temperatures. The magnetization and temperature at which ferromagnetic ordering evolves are found to increase on increasing the oxidation degree. The tuning of non-linear optical and magnetic properties of graphene oxide by oxidation/reduction thus provides an easy way to endow graphene oxide with tunable physical features highly required in both optoelectronics and spintronics applications

Solvent Molding of Organic Morphologies Made of Supramolecular Chiral Polymers

The self-assembly and self-organization behavior of uracil-conjugated enantiopure (R)- or (S)-1,1′-binaphthyl-2,2′-diol (BINOL) and a hydrophobic oligo(p-phenylene ethynylene) (OPE) chromophore exposing 2,6-di(acetylamino)-pyridine termini are reported. Systematic spectroscopic (UV-vis, CD, fluorescence, NMR, and SAXS) and microscopic studies (TEM and AFM) showed that BINOL and OPE compounds undergo triple H-bonding recognition, generating different organic nanostructures in solution. Depending on the solvophobic properties of the liquid media (toluene, CHCl3, CHCl3/CHX, and CHX/THF), spherical, rod-like, fibrous, and helical morphologies were obtained, with the latter being the only nanostructures expressing chirality at the microscopic level. SAXS analysis combined with molecular modeling simulations showed that the helical superstructures are composed of dimeric double-cable tape-like structures that, in turn, are supercoiled at the microscale. This behavior is interpreted as a consequence of an interplay among the degree of association of the H-bonded recognition, the vapor pressure of the solvent, and the solvophobic/solvophilic character of the supramolecular adducts in the different solutions under static and dynamic conditions, namely solvent evaporation conditions at room temperature. (Chemical Equation Presented)