37 research outputs found

    Ozone in Lombardy: Years 1998-1999

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    Photochemical pollutants, especially ozone, have reached very high levels in Lombardy in recent years, with peaks of up to 150 ppb in late spring and summer. Lombardy, lying on the Po Plain, supports a large number of cities and industries and these, along with heavy traffic, produce copious amounts of primary pollutants such as nitrogen oxides and numerous volatile organic compounds. Furthermore, the peculiar orography of this region fosters the stagnation of air masses on a basin-scale and the presence of diurnal breezes towards northern areas, along with the evolution of the Mixing Layer, spread the polluted air masses over a large territory. Numerous stations in Lombardy give the concentrations of ozone and of nitrogen oxides. In this paper, ozone measurements carried out at the plain area around Milan and at pre-alpine sites in the spring and summer 1998 and 1999 will be shown and discussed, focusing on the months of May and July. The study of temporal and spatial behaviour of ozone goes hand in hand with the analysis of the Boundary Layer’s evolution. A number of radon stations were operating in Milan and in other sites in Lombardy. Measurements of atmospheric concentrations of radon yield an index of atmospheric stability, of the formation of thermal inversion, of convective turbulence, and of the movement of air masses, and hence they are very relevant to the understanding of the conditions of atmospheric pollutants

    A large-scale study of the random variability of a coding sequence: a study on the CFTR gene

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    Coding single nucleotide substitutions (cSNSs) have been studied on hundreds of genes using small samples (ngapproximate to100-150 genes). In the present investigation, a large random European population sample (average ngapproximate to1500) was studied for a single gene, the CFTR ( Cystic Fibrosis Transmembrane conductance Regulator). The nonsynonymous (NS) substitutions exhibited, in accordance with previous reports, a mean probability of being polymorphic (q>0.005), much lower than that of the synonymous ( S) substitutions, but they showed a similar rate of subpolymorphic (q<0.005) variability. This indicates that, in autosomal genes that may have harmful recessive alleles (nonduplicated genes with important functions), genetic drift overwhelms selection in the subpolymorphic range of variability, making disadvantageous alleles behave as neutral. These results imply that the majority of the subpolymorphic nonsynonymous alleles of these genes are selectively negative or even pathogenic

    Haplotype block structure study of the CFTR gene. Most variants are associated with the M470 allele in several European populations

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    An average of about 1700 CFTR (cystic fibrosis transmembrane conductance regulator) alleles from normal individuals from different European populations were extensively screened for DNA sequence variation. A total of 80 variants were observed: 61 coding SNSs (results already published), 13 noncoding SNSs, three STRs, two short deletions, and one nucleotide insertion. Eight DNA variants were classified as non-CF causing due to their high frequency of occurrence. Through this survey the CFTR has become the most exhaustively studied gene for its coding sequence variability and, though to a lesser extent, for its noncoding sequence variability as well. Interestingly, most variation was associated with the M470 allele, while the V470 allele showed an 'extended haplotype homozygosity' (EHH). These findings make us suggest a role for selection acting either on the M470V itself or through an hitchhiking mechanism involving a second site. The possible ancient origin of the V allele in an 'out of Africa' time frame is discussed

    Preparation And Characterization Of A New Microwave Immobilized Poly(2-phenylpropyl)methylsiloxane Stationary Phase For Reversed Phase High-performance Liquid Chromatography.

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    A new reversed phase high-performance liquid chromatography (RP-HPLC) stationary phase was prepared and its chromatographic and physical-chemical properties were evaluated. The new stationary phase was prepared with a silica support and poly(2-phenylpropyl)methylsiloxane (PPPMS), a phenyl type polysiloxane copolymer. Since this is a new copolymer and there is little information in the literature, it was submitted to physical-chemical characterization by infrared spectroscopy and thermogravimetry. The chromatographic phase was prepared through sorption and microwave immobilization of the copolymer onto a silica support. The chromatographic performance was evaluated by employing test procedures suggested by Engelhardt and Jungheim, Tanaka and co-workers, Neue, and SzabĂł and CsatĂł. These test mixtures provide information about the hydrophobic selectivity, silanophilic activity, ion-exchange capacity, shape selectivity and interaction with polar analytes of the new Si-PPPMS reversed phase. Stability tests were developed using accelerated aging tests under both basic and acidic conditions to provide information about the lifetime of the packed columns.1297113-2
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