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Fluorescence spectroscopy has been extensively investigated for disease diagnosis. In this framework, optical tissue phantoms are widely used for validating the biomedical device system in a laboratory environment outside of clinical procedures. Moreover, it is fundamental to consider that there are several scattering components and chromophores inside biological tissues and the interplay between scattering and absorption may result in a distortion of the emitted fluorescent signal. In this work, the photophysical behaviour of a set of liquid, tissue-like phantoms containing different compositions was analysed: phosphate buffer saline (PBS) was used as the background medium, low fat milk as a scatterer, Indian ink as an absorber and protoporphyrin IX (PpIX) dissolved in dimethyl formamide (DMF) as a fluorophore. We examined the collected data in terms of the impact of surfactant Tween-20 on the background medium, scattering effects and combination of scattering and absorption within a luminescent body on PpIX. The results indicated that the intrinsic emission peaks are red shifted by the scattering particles or surfactant, whilst the scattering agent and the absorbent can alter the emission intensity substantially. We corroborated that phantoms containing higher surfactant content (>0.5% Tween 20) are essential to prepare stable aqueous phantoms.

Fluorescence spectroscopy has been extensively investigated for disease diagnosis. In this framework, optical tissue phantoms are widely used for validating the biomedical device system in laboratory environment outside clinical procedures. Moreover, it is fundamental to consider that there are several scattering components and chromophores inside biological tissues and the interplay between scattering effects and absorption can result in a distortion of the emitted fluorescence signal. In this work, the photophysical behaviour of a set of liquid tissue like phantoms containing different compositions was analysed: phosphate buffer saline (PBS) was used as background medium, low fat milk as a scatterer, India ink as an absorber and PpIX dissolved in dimethyl formamide (DMF) as fluorophore. We examined the collected data in terms of the impact of surfactant Tween-20 on the background medium, scattering effects and combination of scattering and absorption within a luminescent body on PpIX. The results indicated that the intrinsic emission peaks are red-shifted by the scattering particles or surfactant, whilst the scatterer and absorber can alter the emission intensity substantially. We corroborated that phantoms containing higher surfactant content (< 0.5% Tween 20) are essential to prepare a stable aqueous phantoms.

Computer codes are widely used to predict heat transfer fields. Modeling is accomplished in multidimensional media with homogenous or not homogenous thermal conductivity, with or without volume heat sources and enthalpy flux. This paper compares the analytical solution of temperature fields in a few physical cases such as aliment cakes, capacitors, gas turbine blades, tanks with infinite element computer results and experimental results. The analytical solution of heat transfer partial differential equations presented in this paper appears in the form of the sum of effects. One of them is an infinite series in term of eigenvalues that is easily managed through mathematical commercial codes available even for palmar calculations. A comparison with experimental results shows that the concept of analytical solution has application in many physical phenomena without going to the complexity of computer code modeling.

We report on the optical and photo-physical properties of a fluorinated poly(p-phenylenevinylene) derivative, namely poly(2-methoxy-5-[(2-ethylhexyl)oxy]-1,4-phenylenedifluorovinylene) (MEH-PPDFV) and we compare them with those of the well-known non fluorinated reference system, poly(2-methoxy-5-[(2-ethylhexyl)oxy]-1,4-phenylenevinylene) (MEH-PPV) synthesized with the same procedure. Remarkable blue-shifts of absorption and emission spectra of MEH-PPDFV with respect to MEH-PPV are observed, due to the larger distortion from planarity of the fluorinated species. In addition, the blue-shift for optical transitions in absorption spectra is more pronounced than in emission ones, since the molecule conformation in the excited states is more planar than in the ground one. Microsecond photo-induced absorption spectra of MEH-PPDFV reveal three bands possessing spectral properties and/or kinetics different from those observed for MEH-PPV. The assignment of these transitions is provided in terms of free and trapped polarons as well of triplet excitons. Free-polarons have an intrinsic decay constant of 3 μs, while the trapping dynamics has a longer kinetics of 40 μs. The triplet exciton, instead, shows a monoexponetial decay behavior of constant about 10 μs.

An all-polymer photonic structure constituted by a distributed Bragg reflector topped with an ultrathin fluorescent polymer film has been studied. A Bloch surface wave resonance has been exploited to improve pumping efficiency. A strongly polarization and angle dependent fluorescence signal is found with respect to the light pumping beam and the emitted wavelength. Matching the most favorable condition for the pump coupling and the collection geometry, the signal obtained from the structure appears to be two orders of magnitude larger than the one of the bare emitting film.

Ultrathin films of silica realized by sol-gel synthesis and dip-coating techniques were successfully applied to predefined metal/polymer plasmonic nanostructures to spectrally tune their resonance modes and to increase their sensitivity to local refractive index changes. Plasmon resonance spectral shifts up to 100 nm with slope efficiencies of ∼8 nm/nm for increasing layer thickness were attained. In the ultrathin layer regime (

An investigation of the permittivity and ac conductivity was performed for the first time on the isostructural tetrasubstituted alkylammonium (CH 3)4NBF4 and (CH3) 4NClO4 single crystals, in the wide temperature range 12-300 K. For both the explored compounds, an orientational order/disorder phase transition was brought out as a result of the overlapping of two distinct transitions occurring with different dynamics. The first one is the settlement of a stable array, at low temperature, of the anionic groups (orientationally disordered at RT) with a first order character; the second one is the correspondent cationic sublattice rearrangement with the characteristics of second order. The critical temperatures and limits of the transitions were defined. Different conductivity processes above and below the transition were detected and analyzed. At lower temperatures the intra- and inter-molecular motions of the cationic group were brought out through their contribution to the dielectric constant. The temperature values of the freezing out of the vibrational motions were experimentally established for both the observed ionic crystals. Furthermore, the IR spectroscopy has provided spectra of the vibrational modes in the different phases below and above the phase transition, in excellent agreement with the dielectric data. In a general perspective, the obtained results clearly suggest that the thermal evolution displayed by the two investigated compounds is characteristic of the isostructural tetramethylammonium salts; the expected variations for different anionic groups are discussed. © 2014 Elsevier B.V. All rights reserved

A 15 Kg/h pulverized fuel two dimensional furnace was used to determine combustion efficiency, ignition stability, CO, C m H n , NO x profiles of experimental combustors under oxygen-lean and variable excess vitiated air conditions for applications to gas turbine-steam turbine combined engines. A domestic bituminous coal mined in Sardegna was investigated. Results show that the total vitiated air excess must be maintained above 30% and oxygen content in the primary stream cannot drop below 17% to avoid a carbon loss of over 3% wt. and unsteady flame formation. The secondary air oxygen content has a lesser influence on combustion efficiency: the tests performed show that an amount of 15% oxygen is sufficient to support a steady flame with over 0.97 combustion efficiency, if the proper swirl generator is used and the total excess of oxidizer is above the limit of 30%. The secondary vitiated air temperature and an inertial vortex generator offered a successful method of providing swirling turbulent coal flame and smoke, CO, and unburned hydrocarbons under environmental conditions.