Socioeconomic position and health status of people who live near busy roads: the Rome Longitudinal Study (RoLS).

BACKGROUND: Subjects living close to high traffic roads (HTR) are more likely to suffer from air-pollution related morbidity and mortality. The issue has large public health consequences but few studies have described the main socio-demographic characteristics of people exposed to traffic. OBJECTIVES: To characterise a large cohort of residents in Rome according to different measures of traffic exposure, socioeconomic position (SEP), and baseline health status. METHODS: Residents of Rome in October 2001 were selected. Individual and area-based SEP indices were available. GIS was used to obtain traffic indicators at residential addresses: distance from HTR (> = 10,000 vehicles/day), length of HTR, average daily traffic count, and traffic density within 150 meters of home. Hospitalisations in the 5-year period before enrolment were used to characterise health status. Logistic and linear regression analyses estimated the association between traffic exposure and socio-demographic characteristics. RESULTS: We selected 1,898,898 subjects with complete SEP information and GIS traffic indicators. A total of 320,913 individuals (17%) lived within 50 meters of an HTR, and 14% lived between 50 and 100 meters. These proportions were higher among 75+ year-old subjects. Overall, all traffic indicators were directly associated with SEP, with people living in high or medium SEP areas or with a university degree more likely to be exposed to traffic than people living in low SEP areas or with a low level of education. However, an effect modification by area of residence within the city was seen and the association between traffic and SEP was reversed in the city centre. CONCLUSIONS: A large section of the population is exposed to traffic in Rome. Elderly people and those living in areas of high and medium SEP tend to be more exposed. These findings are related to the historical stratification of the population within the city according to age and socioeconomic status.

Chiral nanoribbons based on doubly-linked oligo-perylene bisimides.

A facile strategy towards conformationally stable chiral ladder-type oligo-perylene bisimides is established via copper-mediated Ullmann coupling. Absolute configurations are determined with the help of quantum-chemical calculations.

n-Type charge transport and mobility of fluorinated perylene bisimide semiconductors.

The intramolecular and intermolecular charge transport parameters are evaluated quantum chemically for three fluorinated derivatives of perylene bisimide (PBI) semiconductors, two of which feature a twisted PBI core. Charge transfer rates are computed within the Marcus-Levich-Jortner formalism including a single effective mode treated quantum mechanically and are injected in a kinetic Monte Carlo scheme to propagate the charge carrier in the crystal and to estimate charge mobilities at room temperature. The relative order of computed mobilities agrees with the observed trend, and the largest mobility is computed for the planar PBI derivative. It is suggested that thermally induced disorder effects should contribute considerably to the observed large mobility of the planar PBI derivative, while a retardation effect induced by the presence of alternating slow and fast jumps along pi-stacked PBI columns is responsible for the lower mobilities of the two twisted derivatives. The computed parameters reveal the subtle interplay between intramolecular and intermolecular contributions to the charge carrier propagation in these organic semiconductors and may guide the design of more efficient architectures.

Revealing excited state interactions by quantum-chemical modeling of vibronic activities: the R2PI spectrum of adenine.

We present a computational study encompassing quantum-chemical calculations of the ground and low-lying excited states of 9H-adenine and modeling of vibronic activities associated with the S(0) --> L(b) and S(0) --> n pi* transitions. Minima on the ground and excited states and the saddle point on the n pi* potential energy surface are determined with CASSCF calculations. Vibrational frequencies are computed at the same level of theory on ground and excited states while transition dipole moments and oscillator strengths are estimated, at the optimized geometries, with CASPT2//CASSCF calculations. Modeling of vibronic activities includes both Franck-Condon and Herzberg-Teller induced contributions. While the adopted harmonic approximation is acceptable for the S(0) --> L(b) transition and allows the assignment of several observed bands in the R2PI spectrum of adenine, the computed anharmonic potential along the puckering coordinate in the n pi* state requires a different treatment. To this end the vibronic levels and intensities associated with vibronic transitions in the puckering coordinate are evaluated by numerical solution of the 2D potential including the anharmonic puckering coordinate. All the remaining vibrational coordinates are treated as harmonic. On the basis of the modeling, the four major bands in the R2PI spectrum of adenine are assigned, along with a number of minor bands in the spectra.

Heterocyclic annelated di(perylene bisimide): constructing bowl-shaped perylene bisimides by the combination of steric congestion and ring strain.

In this paper, we present the synthesis of S- and N-heterocyclic annelated di(perylene bisimide) with extraordinary doubly bowl-shaped structures. The structures of fused PBI bowls confirmed by single-crystal X-ray structure analysis and temperature-dependent (1)H NMR are realized by the introduction of the steric congestion in nonbay regions and by the concurrent formation of the five-membered heterorings strain in bay regions. On the basis of the geometry obtained from the X-ray analysis, the maximum POAV1 pyramidalization angle is found in N-heterocyclic annelated diPBI 7, as large as 4.7 degrees , indicating the formation of two PBI bowls with significant curvatures. Furthermore, to assist the electrochemical and spectroscopic characterization of the two bowl-shaped derivatives and to assess the influence of heteroatoms on the bowl curvature, quantum-chemically optimized atomic structures, electronic properties, and optical signatures were computed with density functional theory.

Tuning fluorescence lifetimes through changes in Herzberg-Teller activities: the case of triphenylene and its hexamethoxy-substituted derivative.

The fluorescence spectra of triphenylene (TP) and 2,3,6,7,10,11-hexamethoxy-triphenylene (HMTP) are measured in glass matrices, and the vibronic structure associated with the electronic spectra is simulated with the help of quantum chemically computed molecular parameters. Franck-Condon (FC) and Herzberg-Teller (HT) mechanisms are included. For excited-state calculations, both configuration interaction with single excitations (CIS) and time-dependent density functional theory (TDDFT) are employed. It is shown that the FC activity is associated with modes of similar shape and frequency in both molecules, while the HT-induced false origins with the largest activity are associated with rather different frequencies and normal coordinates as a result of the mixing and energy lowering of the low-lying allowed excited states in HMTP. The increased HT activity explains the reduced S(1) state lifetime in the substituted TP, in turn driven by the excited-state rearrangement occurring upon substitution of the TP core.

Resistive molecular memories: influence of molecular parameters on the electrical bistability.

The electrical bistability behavior of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) along with two additional benzoquinone derivatives (TCQ and TCN) and pentacene (PNT) is investigated by computing intra- and intermolecular charge transfer parameters and by comparing the efficiency of bulk charge transport and charge injection at the electrode/organic interface in the presence of neutral and charged molecular species. The bulk charge transport is modeled assuming a charge hopping regime and by computing hopping rates and mobilities. Molecular dynamics simulations are carried out to estimate the effect of thermal disorder on charge transfer integrals. The efficiency of the interface transport is estimated by comparing the electron affinities of benzoquinone derivatives and the ionization potential of pentacene with the work function of commonly employed electrodes. It is shown that the observed memory effect can be rationalized in terms of an interplay of the two transport mechanisms by showing that the OFF state is dominated by interface limited phenomena and the ON state may be determined also by bulk transport limited phenomena. While the contribution of collective effects cannot be ruled out for the macroscopic memory phenomenon, we show that, at a molecular level, sizable intramolecular reorganization energies are fundamental for the efficiency of the device, provided their magnitude does not hamper the charge transport across the device. It is suggested that control over molecular parameters might be exploited to design more efficient resistive molecular memories.

Evaluation of the best compromise between the urban air quality monitoring resolution by diffusive sampling and resource requirements.

The need to collect data representative of overall urban pollution is all-important in order to monitor the population exposure. High spatial resolution monitoring using diffusive samplers allows studying of the urban pollutant distribution, thus enabling deeper investigation of their generation and diffusion mechanisms. Nevertheless, such a monitoring campaign has a certain cost. In this study we point out how to find the best compromise between the number of necessary measurements and the affordable costs for monitoring campaigns. We also describe an innovative method for the proper design of a fixed urban monitoring network by means of preliminary high spatial resolution campaigns using diffusive samplers. Four European capital cities (Dublin, Madrid, Paris and Rome) were monitored six times, each time for seven days. Benzene, toluene, ethylbenzene, xylenes (BTEX) and NO(2) concentrations were measured at 146 sites in Dublin, 293 in Madrid, 339 in Paris and 290 in Rome. Multiscale grids have been drawn which ranged in mesh size from 500 m to 2 km. The statistical processing of data produced a twofold result: the creation of isoconcentration maps with geostatistical procedures, and an algorithm aimed at locating the minimum number of sampling sites where the fixed monitoring stations should be placed. Average urban levels estimated on the basis of these selected sites differ by less than 8% from those calculated on the whole populations of the sampled points. The aim of this work is to investigate how far the resolution of a monitoring campaign of urban pollution by diffusive sampling can be reduced, thus making the monitoring less expensive in terms of human and financial resources, while preserving the same quality of the results that could be achieved with a higher resolution. We found that there is no significant loss of information when the resolution of the monitoring grid for BTEX is lowered to a mesh size of 1.85 km, that is a sampling site each 3.4 km(2), and that the minimum number of sampling sites to be used is N = 0.29 A, where A is the urban surface to be monitored (in km(2)). As the spatial distribution of NO(2) is less sensitive to the distance from the emission source than that of BTEX, this relationship could be retained as a valid lower limit for the mesh grid size also for NO(2) monitoring.

Resonance Raman contribution to the D band of carbon materials: modeling defects with quantum chemistry.

Polycyclic aromatic hydrocarbons (PAHs) are employed to model the Raman features that are generally associated with sp(2) nanostructures in carbon materials or with disorder and defects in graphitic materials. To this end molecular parameters (geometry changes upon electronic excitation, vibrational normal modes, and displacement parameters) are computed with semiempirical quantum-chemical methods for a series of PAHs ranging from 6 to 384 carbon atoms, and Raman intensities are evaluated according to Albrecht's formalism restricted to the A term. The computed preresonance and resonance Raman intensities are compared with available experimental data for hexa-peri-hexabenzocoronene and for pyrene. For the latter compound, simulations carried out at semiempirical and ab initio levels of theory are shown to be of comparable quality. Finally, the collection of displacement parameters computed for the sample of conjugated molecules is used to model the effect of disorder and defects in the Raman response of a carbon material containing sp(2) islands. It is shown that the computed D-band frequency dispersion, with respect to excitation wavelength, reproduces closely the experimental data measured for sp(2) hybridized carbon materials.

Physiological response of Pinus halepensis needles under ozone and water stress conditions.

The aim of this study was to evaluate how physiological processes of potted Pinus halepensis plants, grown under controlled conditions, were affected by ozone (O3) and/or water stress, integrating the gas exchange and biochemical data with fluorescence OJIP polyphasic transient data. Plants submitted to only water stress (T1) and with ozone (T3) showed a strong decrease in stomatal conductance and gas exchange, coinciding with a reduction of maximum yield of photochemistry (varphipo) and very negative values of leaf water potential. Simultaneously, a great increase of both PSII antenna size, indicated by absorption per reaction centre, and electron transport per reaction centre were found. The reduction of photosynthesis in the O3-treated plants (T2) by a slowing down of the Calvin cycle was supported by the increase of related fluorescence parameters such as relative variable fluorescence, heat de-excitation constant, energy de-excitation by spillover, and the decrease of varphipo. We suggest an antagonistic effect between the two stresses to explain the delayed ozone-induced decrease of stomatal conductance values for T3 with respect to T1 plants, by an alteration of the physiological mechanisms of stomatal opening, which involve the increase of intra-cellular free-calcium induced by ABA under co-occurring water shortage. We emphasise the importance of considering the intensity of the individual stress factor in studies concerning the interaction of stresses.