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- Gomez, B., et al.
(author)
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Levels and risk assessment for humans and ecosystems of platinum group elements in the airborne particles of some European cities
- 2002
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In: The Science of the Total Environment. ; 299, s. 1-19
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Journal article (peer-reviewed)abstract
- Traffic is the main source of platinum-group element (PGE) contamination in populated urban areas. There is increasing concern about the hazardous effects of these new pollutants for people and for other living organisms in these areas. Airborne and road dusts, as well as tree bark and grass samples were collected at locations in the European cities of Göteborg (Sweden), Madrid (Spain), Rome (Italy), Munich (Germany), Sheffield and London (UK). Today, in spite of the large number of parameters that can influence the airborne PGE content, the results obtained so far indicate significantly higher PGE levels at traffic sites compared with the rural or non-polluted zones that have been investigated (background levels). The average Pt content in airborne particles found in downtown Madrid, Göteborg and Rome is in the range 7.313.1 pg m−3. The ring roads of these cities have values in the range 4.117.7 pg m−3. In Munich, a lower Pt content was found in airborne particles (4.1 pg m−3). The same tendency has been noted for downtown Rh, with contents in the range 2.22.8 pg m−3, and in the range 0.83.0 and 0.3 pg m−3 for motorway margins in Munich. The combined results obtained using a wide-range airborne classifier (WRAC) collector and a PM-10 or virtual impactor show that Pt is associated with particles for a wide range of diameters. The smaller the particle size, the lower the Pt concentration. However, in particles
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2. |
- Moldovan, M., et al.
(author)
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Environmental risk of particulate and soluble platinum group elements released from gasoline and diesel engine catalytic converters
- 2002
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In: The Science of the Total Environment. ; 296, s. 199-208
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Journal article (peer-reviewed)abstract
- A comparison of platinum-group element (PGE) emission between gasoline and diesel engine catalytic converters is reported within this work. Whole raw exhaust fumes from four catalysts of three different types were examined during their useful lifetime, from fresh to 80 000 km. Two were gasoline engine catalysts (PtPdRh and PdRh), while the other two were diesel engine catalysts (Pt). Samples were collected following the 91441 EUDC driving cycle for light-duty vehicle testing, and the sample collection device used allowed differentiation between the particulate and soluble fractions, the latter being the most relevant from an environmental point of view. Analyses were performed by inductively coupled plasma-mass spectrometry (ICP-MS) (quadrupole and high resolution), and special attention was paid to the control of spectral interference, especially in the case of Pd and Rh. The results obtained show that, for fresh catalysts, the release of particulate PGE through car exhaust fumes does not follow any particular trend, with a wide range (onetwo orders of magnitude) for the content of noble metals emitted. The samples collected from 30 00080 000 km present a more homogeneous PGE release for all catalysts studied. A decrease of approximately one order of magnitude is observed with respect to the release from fresh catalysts, except in the case of the diesel engine catalyst, for which PGE emission continued to be higher than in the case of gasoline engines. The fraction of soluble PGE was found to represent less than 10% of the total amount released from fresh catalysts. For aged catalysts, the figures are significantly higher, especially for Pd and Rh. Particulate PGE can be considered as virtually biologically inert, while soluble PGE forms can represent an environmental risk due to their bioavailability, which leads them to accumulate in the environment.
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3. |
- Palacios, M.A., et al.
(author)
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Platinum-group elements: quantification in collected exhaust fumes and studies of catalyst surfaces
- 2000
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In: The Science of the Total Environment. ; 257, s. 1-15
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Journal article (peer-reviewed)abstract
- Automotive catalytic converters, in which Pt, Pd and Rh (platinum-group elements; PGEs) are the active components for eliminating several noxious components from exhaust fumes, have become the main source of environmental urban pollution by PGEs. This work reports on the catalyst morphology through changes in catalyst surface by scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDX) and laser-induced breakdown spectrometry (LIBS) from fresh to aged catalytic converters. The distribution of these elements in the fresh catalysts analysed (PtPdRh gasoline catalyst) is not uniform and occurs mainly in a longitudinal direction. This heterogeneity seems to be greater for Pt and Pd. PGEs released by the catalysts, fresh and aged 30 000 km, were studied in parallel. Whole raw exhaust fumes from four catalysts of three different types were also examined. Two of these were gasoline catalysts (PtPdRh and PdRh) and the other two were diesel catalysts (Pt). Samples were collected following the 91441 EUDC driving cycle for light-duty vehicle testing. The results show that at 0 km the samples collected first have the highest content of particulate PGEs and although the general tendency is for the release to decrease with increasing number of samples taken, exceptions are frequent. At 30 000 km the released PGEs in gasoline and diesel catalysts decreased significantly. For fresh gasoline catalysts the mean of the total amount released was approximately 100, 250 and 50 ng km−1 for Pt, Pd and Rh, respectively. In diesel catalysts the Pt release varied in the range 400800 ng km−1. After ageing the catalysts up to 30 000 km, the gasoline catalysts released amounts of Pt between 6 and 8 ng km−1, Pd between 12 and 16 ng km−1 and Rh between 3 and 12 ng km−1. In diesel catalysts the Pt release varied in the range 108150 ng km−1. The soluble portion of PGEs in the HNO3 collector solution represented less than 5% of the total amount for fresh catalysts. For 30 000 km the total amount of soluble PGEs released was similar or slightly higher than for 0 km.
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4. |
- Rioux, John D., et al.
(author)
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Genetic variation in the 5q31 cytokine gene cluster confers susceptibility to Crohn disease
- 2001
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In: Nature Genetics. - : Nature Publishing Group. - 1061-4036 .- 1546-1718. ; 29:2, s. 223-228
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Journal article (peer-reviewed)abstract
- Linkage disequilibrium (LD) mapping provides a powerful method for fine-structure localization of rare disease genes, but has not yet been widely applied to common disease1. We sought to design a systematic approach for LD mapping and apply it to the localization of a gene (IBD5) conferring susceptibility to Crohn disease. The key issues are: (i) to detect a significant LD signal (ii) to rigorously bound the critical region and (iii) to identify the causal genetic variant within this region. We previously mapped the IBD5 locus to a large region spanning 18 cM of chromosome 5q31 (P<10−4). Using dense genetic maps of microsatellite markers and single-nucleotide polymorphisms (SNPs) across the entire region, we found strong evidence of LD. We bound the region to a common haplotype spanning 250 kb that shows strong association with the disease (P<2×10−7) and contains the cytokine gene cluster. This finding provides overwhelming evidence that a specific common haplotype of the cytokine region in 5q31 confers susceptibility to Crohn disease. However, genetic evidence alone is not sufficient to identify the causal mutation within this region, as strong LD across the region results in multiple SNPs having equivalent genetic evidence—each consistent with the expected properties of the IBD5 locus. These results have important implications for Crohn disease in particular and LD mapping in general.
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5. |
- Robinson, SD, et al.
(author)
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High-spin structures and band termination effects in Cd-104
- 2002
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In: Journal of Physics G: Nuclear and Particle Physics. - : IOP Publishing. - 0954-3899. ; 28:6, s. 1415-1431
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Journal article (peer-reviewed)abstract
- High-spin states in the neutron-deficient isotope Cd-104 were populated using the Cr-50(Ni-58,4p)Cd-104 reaction at a beam energy of 250 MeV The level scheme has been extended using triple gamma-ray coincidences to a spin of 29h and an excitation energy of 18.2 MeV. Several collective structures involving the excitation of h(11/2) neutrons have been observed to spins approaching 30h. The high-spin structure has been compared to the results of cranked Nilsson-Strutinsky calculations.
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