Viscosity of mixtures of polymers and microemulsions — the Huggins interaction coefficient

Microemulsions used in enhanced oil recovery are usually used in conjunction with a polymer solution that provides mobility control by reducing the permeability of the formation and/or increasing the viscosity of the injected fluid. Microemulsions, which are mixtures of at least four components — water, oil, surfactant and cosurfactant (and, usually, inorganic salts) are complex even in the absence of polymer and consequently, studies of their phenomenon tend to be phenomenological. An approach found to be useful to circumvent this has been to consider the microemulsion particles dispersed in their external phase to be macromolecules which retain their integrity when diluted with external phase or when mixed with polymers. Thus the dispersed phase components are treated as a pseudocomponent. If this approach is followed, many features of the phase diagram of polymer-microemulsion mixtures can be rationalized. It is therefore of some interest to determine whether a similar approach can be used to understand or predict the viscosity of mixtures in which a simple mixing rule for viscosities can be utilized to gain further insight into the polymer-microemulsion interaction.     

Laser cleaning of stone by different laser pulse duration and wavelength

The present work focuses on the main phenomenological features of stone cleaning by lasers. These are the removal rate, cleaning degree, and chromatic appearance of the treated surface associated with different conservation problems and laser parameters. A set of three different outdoor stone conservation problems were investigated here. The measurement of the ablation rates were carried out on encrusted stone artifacts and two sets of standards in order to derive general behaviors through repeatable measurements. The analysis of the irradiation tests provided quantification of the different efficiencies, cleaning degree, and chromatic appearances associated with the fundamental harmonic of Q-switching, long Q-switching, and short free-running Nd:YAG lasers (1064 nm), as well as with the second harmonic of Q-switching sources (532 nm).     

Characterization of copper alloys of archaeometallurgical interest using neutron diffraction: a systematic calibration study

Neutron diffraction experiments have been performed on laboratory-prepared samples of copper alloys to determine their microscopic phase characteristics. The aim of this experiment is to set up a database that can be used in future neutron diffraction measurements on metal samples mainly of archaeological interest.     

Applications of TOF neutron diffraction in archaeometry

Neutron radiation meets the demand for a versatile diagnostic probe for collecting information from the interior of large, undisturbed museum objects or archaeological findings. Neutrons penetrate through coatings and corrosion layers deep into centimetre-thick materials, a property that makes them ideal for non-destructive examination of objects for which sampling is impractical or unacceptable. A particular attraction of neutron techniques for archaeologists and conservation scientists is the prospect of locating hidden materials and structures inside objects. Time-of-flight (TOF) neutron diffraction allows for the examination of mineral and metal phase contents, crystal structures, grain orientations, and microstructures as well as micro- and macro strains. A promising application is texture analysis which may provide clues to the deformation history of the material, and hence to specific working processes. Here we report on instructive examples of TOF neutron diffraction, including phase analyses of medieval Dutch tin-lead spoons, texture analyses of bronze specimens as well as of 16th-century silver coins. PACS 61.12.-q; 81.05.Bx; 81.70.Jd     

CONTROLLING THE 3D NANOSCALE ORGANIZATION OF BULK HETEROJUNCTION POLYMER SOLAR CELLS

In this study,the three dimensional nanoscale organization in the photoactive layers of poly(3-hexylthiophene) (P3HT) and a methanofullerene derivative (PCBM) is revealed by transmission electron tomography.After annealing treatment,either at elevated temperature or during slow solvent evaporation,nanoscale interpenetrating networks are formed with high crystalline order and favorable concentration gradients of both components through the thickness of the photoactive layer.Such a tailored morphology acco...     

Chemometric tools improving the determination of anti-inflammatory and antiepileptic drugs in river and wastewater by solid-phase microextraction and liquid chromatography diode array detection

An analytical method for the simultaneous determination of seven non-steroidal anti-inflammatory drugs (naproxen, ketoprofen, diclofenac, piroxicam, indomethacin, sulindac and diflunisal) and the anticonvulsant carbamazepine in river and wastewater is reported. The method involves pre-concentration and clean-up by solid-phase microextraction using polydimethylsiloxane/divinylbenzene fibers, followed by liquid chromatography with diode array detection analysis. Owing to the fact that river water samples did not contain interferences and no sensitivity changes due to sample matrix were observed, external calibration was implemented. Standardization was also applied in order to carry out the prediction step by preparing only two diluted standards that were subjected to the pre-concentration step and a set of standards prepared in solvent. For the analysis of wastewater samples, in contrast, it was necessary to implement standard addition calibration in combination with the multivariate curve resolution-alternating least squares (MCR-ALS) algorithm, which allowed us to overcome matrix effect and exploit the second order advantage. Recoveries ranging from 72% to 125% for all pharmaceuticals proved the accuracy of the proposed method in river water samples. On the other hand, wastewater sample recoveries ranged from 83% to 140% for all pharmaceuticals, showing an acceptable performance – considering this sample contains no modeled interferences.     

Optical signal-to-noise ratio measurement by optical homodyne tomography

An all-fiber optical homodyne tomography setup is introduced that measures the optical signal-to-noise ratio through reconstruction of the photon statistics. The scheme described has been conceived for applications to optical communications. In particular, the signal-to-noise ratio has been evaluated at lambda= 1.55 microm as a function of the received power. From the experimental data, in the case of optically amplified signals, the amplifier noise figure can be estimated.     

Removal of overpaintings from easel paintings using LQS Nd:YAG laser

The removal of overpaintings from valuable easel paintings represents a very difficult challenge, which is traditionally approached using solvents and moderate mechanical actions. Here, we explore for the first time the potential of Long Q-Switching Nd:YAG (1,064 nm) laser with a pulse duration of 120 ns for selective ablation of overpainting layers. Mock-ups were prepared in order to approach in a systematic way a concrete uncovering problem concerning a modern painting on canvas. The former were prepared according to the stratigraphy and material compositions of the latter, as measured using optical and ESEM-EDX microscopy along with infrared and portable Raman spectroscopy. The parameterization achieved on the mock-ups allowed interpreting and maximizing the selectivity of the laser conservation treatment carried out on the real case.     

Depth-dependent calibration for quantitative elemental depth profiling of copper alloys using laser-induced plasma spectroscopy

This work presents new calibration procedures for deep elemental depth profile analysis of bronze artifacts. A simple ablation model is developed for the estimation of the ablation rate and hence for deriving the depth spatial calibration scale. Elemental quantification is obtained through the construction of calibration surfaces, using reference samples of known composition, relating laser-induced plasma spectroscopy (LIPS) intensity ratios, content of atomic species and number of laser pulses. Such a method represents a refinement of the standard LIPS quantification approach based on calibration curves, which is extended here to the generation of significantly deep craters into the material under investigation up to several hundred microns. The depth dependence of the calibration surfaces measured is discussed in the framework of a simplified model of depth-dependent plasma temperature.     

Extended Fuzzy C-Means and Genetic Algorithms to Optimize Power Flow Management in Hybrid Electric Vehicles

The need for personal transportation must be harmonized by considering the impact of so huge number of vehicles on the environment. The adoption of hybrid electric vehicles can provide a sensible improvement from an environmental viewpoint, but at the same time makes more difficult the definition and implementation of the overall powertrain control mechanism. In fact, powertrain control problems are known to be very complex due to conflicting requirements, and this difficulty augments in case of hybrid electric vehicles. Most of the features of the future hybrid electric vehicles are enabled by a new energy flow management unit designed to split the instantaneous power demand between the internal combustion engine and the electric motor, ensuring both an efficient power supply and reduced emissions. Classic approaches that rely on static thresholds, optimized on a fixed drive cycle, cannot face the high dynamicity and unpredictability of real-life drive conditions. The need to actually control a real vehicle stimulates the research of innovative methodologies for the real-time identification of the operating points of each energy source. This paper is framed into this context: after a brief discussion about a non-conventional formalization of the energy flows problem based on a multiobjective function, a knowledge-based control system for splitting the vehicle's power demand between the engine and motor is presented. The proposed approach exploits a fuzzy clustering criterion that combined with a genetic algorithm, permits to achieve better results, both in terms of a reduced computational effort and an improved efficiency of the control system over various driving cycles. To validate the proposed approach, simulation tests and comparisons with other energy management strategies are discussed.