Selective Wrapping and Supramolecular Structures of Polyfluorene-Carbon Nanotube Hybrids

We report on the photophysical properties of single-walled carbon nanotube (SWNT) suspensions In toluene solutions of poly[9,9-dioctylfluorenyl-2,7-diyl](PFO). Steady-state and time-resolved photoluminescence spectroscopy in the near-infrared and visible spectral regions are used to study the interaction of the dispersed SWNTs with the wrapped polymer. Molecular dynamics simulations of the PFO-SWNT hybrids in toluene were carried out to evaluate the energetics of different wrapping geometries. The simulated fluorescence spectra in the visible region were obtained by the quantum chemical ZINDO-CI method, using a sampling of structures obtained from the dynamics trajectories. The tested schemes consider polymer chains aligned along the nanotube axis, where chirality has a minimal effect, or forming helical structures, where a preference for high chiral angles is evidenced. Moreover, toluene affects the polymer structure favoring the helical conformation. Simulations show that the most stable hybrid system is the PFO-wrapped (8,6) nanotube, in agreement with the experimentally observed selectivity.

Sex and socioeconomic inequalities of lung cancer mortality in Barcelona, Spain and Sao Paulo, Brazil

The objective of this paper was to assess sex and socioeconomic inequalities in lung cancer mortality in two major cities of Europe and South America. Official information on mortality and population allowed the estimation of sex- and age-specific death rates for Barcelona, Spain and Sao Paulo, Brazil (1995-2003). Mortality trends and levels were independently assessed for each city and subsequently compared. Rate ratios assessed by Poisson regression analysis addressed hypotheses of association between the outcome and socioeconomic covariates (human development index, unemployment and schooling) at the inner-city area level. Barcelona had a higher mortality in men (76.9/100000 inhabitants) than Sao Paulo (38.2/100 000 inhabitants); although rates were decreasing for the former (-2%/year) and levelled-off for the [after. Mortality in women ranked similarly (9.1 for Barcelona, 11.5 for Sao Paulo); with an increasing trend for women aged 35-64 years (+ 7.7%/year in Barcelona and + 2.4%/year in Sao Paulo). The socioeconomic gradient of mortality in men was negative for Barcelona and positive for Sao Paulo; for women, the socioeconomic gradient was positive in both cities. Negative gradients indicate that deprived areas suffer a higher burden of disease; positive gradients suggest that prosmoking lifestyles may have been more prevalent in more affluent areas during the last decades. Sex and socioeconomic inequalities of lung cancer mortality reinforce the hypothesis that the epidemiologic profile of cancer can be improved by an expanded access to existing technology of healthcare and prevention. The continuous monitoring of inequalities in health may contribute to the concurrent promotion of well-being and social justice.

Species diversity of Leishmania (Viannia) parasites circulating in an endemic area for cutaneous leishmaniasis located in the Atlantic rainforest region of northeastern Brazil

OBJECTIVES To identify the aetiological agents of cutaneous leishmaniasis and to investigate the genetic polymorphism of Leishmania (Viannia) parasites circulating in an area with endemic cutaneous leishmaniasis (CL) in the Atlantic rainforest region of northeastern Brazil. METHODS Leishmania spp. isolates came from three sources: (i) patients diagnosed clinically and parasitologically with CL based on primary lesions, secondary lesions, clinical recidiva, mucocutaneous leishmaniasis and scars; (ii) sentinel hamsters, sylvatic or synanthropic small rodents; and (iii) the sand fly species Lutzomyia whitmani. Isolates were characterised using monoclonal antibodies, multilocus enzyme electrophoresis (MLEE) and polymerase chain reaction-restriction fragment length polymorphism of the internal transcribed spacer region rDNA locus. RESULTS Seventy-seven isolates were obtained and characterised. All isolates were identified as Leishmania (Viannia) braziliensis serodeme 1 based on reactivity to monoclonal antibodies. MLEE identified 10 zymodemes circulating in the study region. Most isolates were classified as zymodemes closely related to L. (V.) braziliensis, but five isolates were classified as Leishmania (Viannia) shawi. All but three of the identified zymodemes have so far been observed only in the study region. Enzootic transmission and multiclonal infection were observed. CONCLUSIONS Our results confirm that transmission cycle complexity and the co-existence of two or more species in the same area can affect the level of genetic polymorphism in a natural Leishmania population. Although it is not possible to make inferences as to the modes of genetic exchange, one can speculate that some of the zymodemes specific to the region are hybrids of L. (V.) braziliensis and L. (V.) shawi.