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Cast films and nanofibers of polyacrylonitrile (PAN) were considered in order to study the chemical reactions occurring during the stabilization and carbonization steps in the thermal conversion of PAN into a carbonaceous structure. Cast films were subjected to a thermal ramp from room temperature to 600 °C in nitrogen or in air, the chemical modifications were observed in situ with infrared spectroscopy in reflection–absorption mode. The thermal process performed on fibers consisted instead in a stabilization step in air (half an hour at 250 °C), followed by a carbonization step in nitrogen up to 800 °C. In nitrogen the chemical modifications started around 300 °C; it is suggested that the majority of nitriles takes part in cyclization and trimerization reactions below 400 °C. During the treatment performed in air the chemical reactions occurred during the isothermal step. Oxygen causes the formation of oxidized species and a faster effective dehydrogenation; at the end of the treatment the samples resembled to a graphitized structure more than the samples heated under nitrogen. Also, the oxidation process was much more effective in char formation. The products obtained on the nanofibers were comparable with the products observed in air on film, but with a higher carbon content. In all thermal treatments a new IR signal around 800 cm −1 appeared, which was attributed to substituted triazine rings formed in the trimerization of nitrile groups of different chains. The data supports the hypothesis of crosslink of the fibers at the beginning of the thermal conversion. The infrared and Raman spectra at 800 °C confirm the carbonization process on the nanofibers. [ABSTRACT FROM AUTHOR]

The increasing vehicular traffic on urban road in network demands effective measure of traffic control on road network, especially at the intersection, where turning movement of vehicle and mixed traffic creates congestion. In congested parts of the cities, traffic control at road intersection is the most efficient method. The Traffic Signal Synchronization is a traffic engineering technique of matching the green light times for a series of intersections to enable the maximum number of vehicles to pass through, thereby reducing stops and delays experienced by motorists. The principal objective of Traffic Signal Synchronization at intersection is to clear maximum number of vehicles through the intersection in a given length and time with least number of accidents, at maximum safe speed and with minimum delay. Synchronizing traffic signals ensures a better flow of traffic and minimizes gas consumption and pollutant emissions. In this paper, we apply different approaches to minimize the total travel time on the network. The Surrogate Method (SM), the Projected Gradient Algorithm (PGA), the Particle Swarm Optimization (PSO) and the Genetic Algorithm (GA) are developed for the Global Optimization of Signal Settings and Traffic Assignment combined problem. Numerical experiments on real test network are reported. [ABSTRACT FROM AUTHOR]

Gelatin (GL) nanofibrous matrices mimicking the complex biological structure of the natural extracellular matrix (ECM) were prepared from aqueous solutions by electrospinning technique. GL nanofibres with a diameter size of around 300nm were obtained optimising the process and solution parameters. To increase the GL stability in aqueous environment γ-glycidoxypropyltrimethoxysilane (GPTMS) was used as GL crosslinker. GPTMS crosslinking did not modify the nanofibrous matrix morphology: fibre diameter and membrane pores size were 327±45nm and 1.64±0.37μm, respectively. The produced GPTMS crosslinked GL nanofibres (GL/GPTMS_NF) were found to support the in vitro adhesion, proliferation and survival of neonatal olfactory bulb ensheating cells (NOBECs). [ABSTRACT FROM AUTHOR]

Abstract: Fourteen explanted Dynesys® spinal devices were analyzed for biostability and compared with a reference, never implanted, control. Both poly(carbonate-urethane) (PCU) spacers and polyethylene-terephthalate (PET) cords were analyzed. The effect of implantation was evaluated through the observation of physical alterations of the device surfaces, evaluation of the chemical degradation and fluids absorption on the devices and examination of the morphological and mechanical features. PCU spacers exhibited a variety of surface damage mechanisms, the most significant being abrasion and localized, microscopic surface cracks. Evidence of oxidation and chain scission were detected on PCU spacers by ATR–FTIR. ATR–FTIR, DSC and hardness measurements also showed a slight heterogeneity in the composition of PCU. The extraction carried out on the PCU spacers revealed the presence of extractable polycarbonate segments. One spacer and all PET cords visually exhibited the presence of adherent biological material (proteins), confirmed by the ATR–FTIR results. GC/MS analyses of the extracts from PET cords revealed the presence of biological fluids residues, mainly cholesterol derivatives and fatty acids, probably trapped into the fiber network. No further chemical alterations were observed on the PET cords. Although the observed physical and chemical damage can be considered superficial, greater attention must be paid to the chemical degradation mechanisms of PCU and to the effect of byproducts on the body. [Copyright &y& Elsevier]

• Estimate the traffic demand integrating information provided by traditional and new technologies. Explore the inherent properties of extended coverage information. • Deal with splitting ratios of demand flows among paths identified by coupled Bluetooth sections. • Derivate the analytical solving procedure. • Increase of the intercepted path flows or spatial coverage leads to more accurate estimates. • Assess the effectiveness of the proposed method on a study network in Rome, Italy. Recent advances in technology have made available numerous new monitoring systems that collect updated traffic measurements both in fixed locations and over specific corridors or paths. Such recent technological developments point to challenging and promising opportunities for Origin-Destination (OD) traffic demand estimation and forecast. Therefore, the aim of this paper is to study how to exploit available information detected by new monitoring devices in the estimation of traffic demand. Starting from the formulation proposed by Spiess (1987, 1990), in this paper a new method to estimate the traffic demand by means of Bluetooth data is proposed. It explores inherent properties of this information in an off-line (and static) context, where mathematical formulation of the estimation problem can be derived. The effectiveness of the proposed method has been investigated in an extensive plan of experiments carried out both on test networks and on a study network consisting in a part of the city of Rome, Italy, obtaining promising results in both applications. [ABSTRACT FROM AUTHOR]