| 1. |
- Janosik, Tomasz, et al.
(author)
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Synthetic, spectroscopic, and X-ray crystallographic studies of [1,2,7,8]tetrathiacyclododecino[4,3-b : 5,6-b': 10,9-b": 11,12-b''']tetraindoles
- 2002
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In: European Journal of Organic Chemistry. - 1434-193X .- 1099-0690. ; :8, s. 1392-1396
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Journal article (peer-reviewed)abstract
- Two conformationally different [1,2,7,8]tetrathiacyclododecino[4,3-b:5,6-b':10,9-b":11,12-b''']tetraind oles 9a and 9b have been isolated in good yields, and the existence of a third conformer 9c in solution was demonstrated by mass spectrometry and H-1 NMR spectroscopy. The interconversions of the tetraindoles 9a-c have also been studied. The conformation of 9b was confirmed by X-ray crystallography, while the conformations of 9a and 9b were assigned on the basis of spectroscopic data, and were also supported by molecular modelling studies. In addition, the elusive dithiin 3 was isolated and the structure was proven by X-ray crystallography.
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| 2. |
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| 3. |
- Janosik, Tomasz, et al.
(author)
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Synthetic, spectroscopic, and X-ray crystallographic studies of [1,2,7,8]tetrathiacyclododecino[4,3-b : 5,6-b': 10,9-b": 11,12-b''']tetraindoles
- 2002
-
In: European Journal of Organic Chemistry. - 1434-193X. ; :8, s. 1392-1396
-
Journal article (peer-reviewed)abstract
- Two conformationally different [1,2,7,8]tetrathiacyclododecino[4,3-b:5,6-b':10,9-b":11,12-b''']tetraind oles 9a and 9b have been isolated in good yields, and the existence of a third conformer 9c in solution was demonstrated by mass spectrometry and H-1 NMR spectroscopy. The interconversions of the tetraindoles 9a-c have also been studied. The conformation of 9b was confirmed by X-ray crystallography, while the conformations of 9a and 9b were assigned on the basis of spectroscopic data, and were also supported by molecular modelling studies. In addition, the elusive dithiin 3 was isolated and the structure was proven by X-ray crystallography. ((C) Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002).
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| 4. |
- Blanco, A, et al.
(author)
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Progress in timing Resistive Plate Chambers
- 2004
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In: Nuclear Instruments and Methods in Physics Research Section A. - 0168-9002 .- 1872-9576. ; 535:1-2, s. 272-276
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Journal article (peer-reviewed)abstract
- Timing RPCs are Resistive Plate Chambers made with glass and metal electrodes separated by precision spacers. Typical gas gaps are a few hundred micrometers wide. Such counters were introduced in 1999 and have since reached timing accuracies below 50 ps sigma with efficiencies above 99% for MIPs. Applications in high-energy physics have already taken place with several more under study. Some recent developments include the extension of the counting rate capability by over one order of magnitude, to 25 kHz/cm(2), with time resolutions below 100 ps sigma. A prototype RPC-based Positron Emission Tomograph yielded a reconstructed point-source resolution of 0.6 mm FWHM and a modified timing RPC design, featuring 50 mum pitch anode strips, allowed to reach extremely good position resolution for hard X-rays in digital readout mode. An analytically solvable model has allowed us to clarify the basic factors influencing the time resolution.
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| 5. |
- Marqués, M., et al.
(author)
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Pressure effects on the structure and vibrations of β- and γ-C3N4
- 2004
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In: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 70:10, s. 104114-
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Journal article (peer-reviewed)abstract
- We present the results of an investigation on the pressure behavior of structural, bonding and vibrational properties of β- and γ-C3N4 phases. Emphasis is focused on the trends of the calculated properties along the A3N4 (A: C, Si, Ge) family. Geometry optimizations and electronic structure calculations are carried out in the framework of the local density functional theory using a planewave-pseudopotential scheme. The equilibrium cell geometry, the isothermal bulk modulus and its pressure derivatives have been evaluated for the two phases in a pressure range up to 400 GPa. The Bader’s Atoms in Molecules formalism is applied to characterize the chemical bonding and the atomic contributions to the bulk compressibility in β- and γ-A3N4 crystals. The calculated stability diagram reveals the occurrence of a hypothetical β-C3N4→γ-C3N4 phase transition around 370 GPa. Γ-point harmonic vibrational modes are computed at selected pressures within the density functional perturbation theory approach. In agreement with recent theoretical calculations, the comparison of the computed Raman vibrational frequencies with experimental estimations for β-C3N4 raises doubts on a previously reported synthesis of this structure. Pressure effects on the vibrational frequencies inform of a reduction of the P63∕m symmetry of the β phase at pressures around 60 GPa and contribute to look into the mechanical stability of the γ phase.
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| 6. |
- Marques, Marcia, et al.
(author)
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Water environments : Anthropogenic pressures and ecosystem changes in the Atlantic drainage basins of Brazil
- 2004
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In: Ambio. - : Royal Swedish Academy of Sciences. - 0044-7447 .- 1654-7209. ; 33:1-2, s. 68-77
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Journal article (peer-reviewed)abstract
- Densely occupied drainage basins and coastal zones in developing countries that are facing economic growth are likely to suffer from moderate to severe environmental impacts regarding different issues. The catchment basins draining towards the Atlantic coast from northeastern to southern Brazil include a wide range of climatic zones and diverse ecosystems. Within its borders lies the Atlantic rain forest, significant extensions of semiarid thorn forests (caatinga), vast tree and scrub woodlands (cerrado) and most of the 6670 km of the Brazilian coast and its marine ecosystems. In recent decades, human activities have increasingly advanced over these natural resources. Littoralization has imposed a burden on coastal habitats and communities. Most of the native vegetation of the cerrado and caatinga was removed and only 7% of the original Atlantic rainforest still exists. Estuaries, bays and coastal lagoons have been irreversibly damaged. Land uses, damming and water diversion have become the major driving forces for habitat loss and aquatic ecosystem modification. Regardless of the contrast between the drought-affected northeastern Brazil and the much more prosperous and industrialized southeastern/southern Brazil, the impacts on habitat and communities were found equally severe in both cases. Attempts to halt environmental degradation have not been effective. Instead of focusing on natural resources separately, it is suggested that more integrated environmental policies that focus on aquatic ecosystems integrity are introduced.
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| 7. |
- Dunlap, Paul V, et al.
(author)
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Genomic polymorphism in symbiotic populations of Photobacterium leiognathi.
- 2004
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In: Environmental Microbiology. - 1462-2912 .- 1462-2920. ; 6:2, s. 145-58
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Journal article (peer-reviewed)abstract
- Photobacterium leiognathi forms a bioluminescent symbiosis with leiognathid fishes, colonizing the internal light organ of the fish and providing its host with light used in bioluminescence displays. Strains symbiotic with different species of the fish exhibit substantial phenotypic differences in symbiosis and in culture, including differences in 2-D PAGE protein patterns and profiles of indigenous plasmids. To determine if such differences might reflect a genetically based symbiont-strain/host-species specificity, we profiled the genomes of P. leiognathi strains from leiognathid fishes using PFGE. Individual strains from 10 species of leiognathid fishes exhibited substantial genomic polymorphism, with no obvious similarity among strains; these strains were nonetheless identified as P. leiognathi by 16S rDNA sequence analysis. Profiling of multiple strains from individual host specimens revealed an oligoclonal structure to the symbiont populations; typically one or two genomotypes dominated each population. However, analysis of multiple strains from multiple specimens of the same host species, to determine if the same strain types consistently colonize a host species, demonstrated substantial heterogeneity, with the same genomotype only rarely observed among the symbiont populations of different specimens of the same host species. Colonization of the leiognathid light organ to initiate the symbiosis therefore is likely to be oliogoclonal, and specificity of the P. leiognathi/leiognathid fish symbiosis apparently is maintained at the bacterial species level rather than at the level of individual, genomotypically defined strain types.
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| 8. |
- Hogland, W, et al.
(author)
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Physical, chemical and biological processes for optimizing decentralized composting
- 2003
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In: Compost Science & Utilization. - 1065-657X. ; 11:4, s. 330-336
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Journal article (peer-reviewed)abstract
- On-site composting of nonpolluted organic wastes avoids costs and energy for transportation since the volume to be transported can be reduced to about 20% of the original. This paper describes the aerobic processes in a small-scale composting reactor, and evaluates how these processes can be optimized. The optimized composting process has a relatively short turnover time for organic matter; at the same time the temperature of about 60degreesC decreases the problems with pathogens and weeds in the mature compost. The compost produced has a high nutritional value, with high concentrations of especially nitrogen, potassium and phosphorus, while the contamination by heavy metals and other toxic substances are very low.
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| 9. |
- Saraiva, Jorge M., et al.
(author)
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Issues in Human GenEthics
- 2001
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In: Genetics in Medicine. - 1098-3600. ; 3:3, s. 218-218
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Journal article (peer-reviewed)
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