A crash-prediction model for road tunnels

Considerable research has been carried out into open roads to establish relationships between crashes and traffic flow, geometry of infrastructure and environmental factors, whereas crash-prediction models for road tunnels, have rarely been investigated. In addition different results have been sometimes obtained regarding the effects of traffic and geometry on crashes in road tunnels. However, most research has focused on tunnels where traffic and geometric conditions, as well as driving behaviour, differ from those in Italy. Thus, in this paper crash prediction-models that had not yet been proposed for Italian road tunnels have been developed. For the purpose, a 4-year monitoring period extending from 2006 to 2009 was considered. The tunnels investigated are single-tube ones with unidirectional traffic. The Bivariate Negative Binomial regression model, jointly applied to non-severe crashes (accidents involving material-damage only) and severe crashes (fatal and injury accidents only), was used to model the frequency of accident occurrence. The year effect on severe crashes was also analyzed by the Random Effects Binomial regression model and the Negative Multinomial regression model. Regression parameters were estimated by the Maximum Likelihood Method. The Cumulative Residual Method was used to test the adequacy of the regression model through the range of annual average daily traffic per lane. The candidate set of variables was: tunnel length (L), annual average daily traffic per lane (AADT_L), percentage of trucks (%Tr), number of lanes (N_L), and the presence of a sidewalk. Both for non-severe crashes and severe crashes, prediction-models showed that significant variables are: L, AADT_L, %Tr, and N_L. A significant year effect consisting in a systematic reduction of severe crashes over time was also detected. The analysis developed in this paper appears to be useful for many applications such as the estimation of accident reductions due to improvement in existing tunnels and/or to modifications of traffic control systems, as well as for the prediction of accidents when different tunnel design options are compared.     

Scheduling flexible manufacturing cells using Tabu Search

Scheduling is an important aspect in the overall control of a flexible manufacturing system. The research presented focuses on production scheduling of jobs within a flexible manufacturing cell (FMC)–one type of flexible manufacturing system. Due to the complexity of the FMC scheduling problem, a 0–1 mixed-integer linear programming (MILP) model is formulated for M machines and N jobs with alternative routings. Although small instances of the problem can be solved optimally with MILP models, a two-stage Tabu Search (TS² ) algorithm that minimises the manufacturing makespan (MS) is proposed to solve medium-to-large-scale problems more efficiently. During Stage I (construction phase), two heuristics are utilised to generate an initial feasible sequence and an initial MS solution. In Stage II (improvement phase), the acquired initial solutions from Stage I are combined with a Tabu Search meta-heuristic procedure that provides improved MS solutions. The TS² algorithm provides tremendous savings in computational time for medium/large-sized multi-machine FMC problems.     

Effect of sodium addition on the preparation of hydroxyapatites and biphasic ceramics

HAP and biphasic ceramics of two different HAP and β-TCP proportions with substituted sodium were prepared through an aqueous precipitation method. The prepared powders were characterized by XRD, thermal analysis, FT-IR and elemental analysis. Sodium was found to incorporate into the apatite structure without showing any significant change in the phase behaviour of the resultant apatites. The substitution of sodium in the calcium deficient apatites tends to form a biphasic mixture of HAP and β-TCP, while the effect of calcination beyond 700 °C and the resultant mixtures were dependent on the initial Ca/P ratios of the precursors. The calculated lattice parameter values for sodium substituted apatites have shown a marginal increase in c-axis values thereby leading to the enlargement of the hexagonal cell volume with respect to the pure HAP prepared under the same experimental conditions. Powders obtained from the present results were stable up to 1200 °C.     

Estimation of the thickness and the optical parameters of several stacked thin films using optimization

The reverse engineering problem addressed in the present research consists of estimating the thicknesses and the optical constants of two thin films deposited on a transparent substrate using only transmittance data through the whole stack. No functional dispersion relation assumptions are made on the complex refractive index. Instead, minimal physical constraints are employed, as in previous works of some of the authors where only one film was considered in the retrieval algorithm. To our knowledge this is the first report on the retrieval of the optical constants and the thickness of multiple film structures using only transmittance data that does not make use of dispersion relations. The same methodology may be used if the available data correspond to normal reflectance. The software used in this work is freely available through the PUMA Project web page (http://www.ime.usp.br/~egbirgin/puma/).     

Synthesis and Biological Evaluation of N‐Substituted Noscapine Analogues

Noscapine is a phthalideisoquinoline alkaloid isolated from the opium poppy Papaver somniferum. It has long been used as an antitussive agent, but has more recently been found to possess microtubule‐modulating properties and anticancer activity. Herein we report the synthesis and pharmacological evaluation of a series of 6′‐substituted noscapine derivatives. To underpin this structure–activity study, an efficient synthesis of N‐nornoscapine and its subsequent reduction to the cyclic ether derivative of N‐nornoscapine was developed. Reaction of the latter with a range of alkyl halides, acid chlorides, isocyanates, thioisocyanates, and chloroformate reagents resulted in the formation of the corresponding N‐alkyl, N‐acyl, N‐carbamoyl, N‐thiocarbamoyl, and N‐carbamate derivatives, respectively. The ability of these compounds to inhibit cell proliferation was assessed in cell‐cycle cytotoxicity assays using prostate cancer (PC3), breast cancer (MCF‐7), and colon cancer (Caco‐2) cell lines. Compounds that showed activity in the cell‐cycle assay were further evaluated in cell viability assays using PC3 and MCF‐7 cells.     

A versatile synthesis method of dendrites-free segmented nanowires with a precise size control

ABSTRACT: We report an innovative strategy to obtain cylindrical nanowires combining well established and low-cost bottom-up methods such as template-assisted nanowires synthesis and electrodeposition process. This approach allows the growth of single-layer or multi-segmented nanowires with precise control over their length (from few nanometers to several micrometers). The employed techniques give rise to branched pores at the bottom of the templates and consequently dendrites at the end of the nanowires. With our method, these undesired features are easily removed from the nanowires by a selective chemical etching. This is crucial for magnetic characterizations where such non-homogeneous branches may introduce undesired features into the final magnetic response. The obtained structures show extremely narrow distributions in diameter and length, improved robustness and high-yield, making this versatile approach strongly compatible with large scale production at an industrial level. Finally, we show the possibility to tune accurately the size of the nanostructures and consequently provide an easy control over the magnetic properties of these nanostructures.     

Distinguishing nanowire and nanotube formation by the deposition current transients

ABSTRACT: High aspect ratio Ni nanowires (NWs) and nanotubes (NTs) were electrodeposited inside ordered arrays of self-assembled pores (approximately 50 nm in diameter and approximately 50 um in length) in anodic alumina templates by a potentiostatic method. The current transients monitored during each process allowed us to distinguish between NW and NT formation. The depositions were long enough for the deposited metal to reach the top of the template and form a continuous Ni film. The overfilling process was found to occur in two steps when depositing NWs and in a single step in the case of NTs. A comparative study of the morphological, structural, and magnetic properties of the Ni NWs and NTs was performed using scanning electron microscopy, X-ray diffraction, and vibrating sample magnetometry, respectively.     

Confocal ultrafast pump-probe spectroscopy: a new technique to explore nanoscale composites

This article is devoted to the exploration of the benefits of a new ultrafast confocal pump-probe technique, able to study the photophysics of different structured materials with nanoscale resolution. This tool offers many advantages over standard stationary microscopy techniques because it directly interrogates excited state dynamics in molecules, providing access to both radiative and non-radiative deactivation processes at a local scale. In this paper we present a few different examples of its application to organic semiconductor systems. The first two are focussed on the study of the photophysics of phase-separated polymer blends: (i) a blue-emitting polyfluorene (PFO) in an inert matrix of PMMA and (ii) an electron donor polythiophene (P3HT) mixed with an electron acceptor fullerene derivative (PCBM). The experimental results on these samples demonstrate the capability of the technique to unveil peculiar interfacial dynamics at the border region between phase-segregated domains, which would be otherwise averaged out using conventional pump-probe spectroscopy. The third example is the study of the photophysics of isolated mesoscopic crystals of the PCBM molecule. Our ultrafast microscope could evidence the presence of two distinctive regions within the crystals. In particular, we could pinpoint for the first time areas within the crystals showing photobleaching/stimulated emission signals from a charge-transfer state.     

New chlorinated amphetamine-type-stimulants disinfection-by-products formed during drinking water treatment

Previous studies have demonstrated high removal rates of amphetamine-type-stimulants (ATSs) through conventional drinking water treatments; however the behaviour of these compounds through disinfection steps and their transformation into disinfection-by-products (DBPs) is still unknown. In this work, for the first time, the reactivity of some ATSs such as amphetamine, methamphetamine, 3,4-methylenedioxyamphetamine (MDA), 3,4-methylenedioxymethamphetamine (MDMA) and 3,4-methylenedioxyethylamphetamine (MDEA) with chlorine has been investigated under simulated and real drinking water treatment conditions in order to evaluate their ability to give rise to transformation products. Two new DBPs from these illicit drugs have been found. A common chlorinated-by-product (3-chlorobenzo)-1,3-dioxole, was identified for both MDA and MDEA while for MDMA, 3-chlorocatechol was found. The presence of these DBPs in water samples collected through drinking water treatment was studied in order to evaluate their formation under real conditions. Both compounds were generated through treatment from raw river water samples containing ATSs at concentration levels ranging from 1 to 15 ng/L for MDA and from 2.3 to 78 ng/L for MDMA. One of them, (3-chlorobenzo)-1,3-dioxole, found after the first chlorination step, was eliminated after ozone and GAC treatment while the MDMA DBP mainly generated after the postchlorination step, showed to be recalcitrant and it was found in final treated waters at concentrations ranging from 0.5 to 5.8 ng/L.     

Rapid Tomato Volatile Profiling by Using Proton‐Transfer Reaction Mass Spectrometry (PTR‐MS)

Abstract: The availability of rapid and accurate methods to assess fruit flavor is of utmost importance to support quality control especially in the breeding phase. Breeders need more information and analytical tools to facilitate selection for complex multigenic traits such as flavor quality. In this study, it is shown that proton‐transfer reaction mass spectrometry (PTR‐MS) is a suitable method to monitor at high sensitivity the emission of volatiles determining the tomato aromatic profile such as hexanal, hexenals, methanol, ethanol, and acetaldehyde. The volatiles emitted by 14 tomato varieties (at red stage) were analyzed by 2 solvent‐free headspace methods: solid‐phase microextraction/gas chromatography MS and PTR‐MS. Multivariate statistics (principal component analysis and cluster analysis) of the PTR‐MS results allow an unambiguous separation between varieties, especially with a clear fingerprinting separation between the different tomato types: round truss, cocktail, and cherry tomatoes. PTR‐MS was also successfully used to monitor the changes in volatile profiles during postharvest ripening and storage. Practical Application: These results show that proton‐transfer reaction mass spectrometry (PTR‐MS) is suited to monitor at high sensitivity the emission of a large number of volatiles that describe the tomato aroma profile. This technology can easily monitor and quantify compounds related to ripening and/or senescence so that it can be used to improve the breeding of new fruit and vegetable cultivars based on volatiles. Moreover, PTR‐MS can be used to monitor changes in volatile profile during ripening and storage.