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  • 1
    Electronic Resource
    Electronic Resource
    Physical and functional characterization of the ColS8 plasmid
    Amsterdam : Elsevier
    Gene 124 (1993), S. 87-92 
    Details
    ISSN: 0378-1119
    Keywords: Recombinant DNA ; colicin production ; immunity ; minicell and maxicell produced proteins ; mobilization ; multicopy vector ; restriction map
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0378-1119(93)90765-U
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  • 2
    Electronic Resource
    Electronic Resource
    Theory for the ultrafast melting and fragmentation dynamics of small clusters after femtosecond ionization (1998)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 109 (1998), S. 1101-1110 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The ultrafast relaxation of small clusters immediately after ultrashort single ionization is studied. We use an electronic model and molecular dynamics simulations to analyze the ionization induced fragmentation dynamics of small Hgn clusters. Our results show that fragmentation consists mainly in emission of single atoms. We also find a remarkable difference between this nonequilibrium unimolecular dissociation and that described by the Rice–Ramsperger–Kassel–Marcus theory. For fixed cluster size, we determine the time-dependent fragmentation probability of a cluster ensemble as a function of the temperature before ionization. A dramatic change of the fragmentation behavior occurs when the temperature before ionization reaches the "melting temperature" of the neutral clusters. For all cluster sizes studied, the temperature dependence of the average fragmentation times after ionization shows a remarkable correlation with the root-mean-square bond length fluctuations δ(T) of the clusters before ionization. This new effect reflects sensitivity of the ultrashort-ionization induced fragmentation dynamics to the melting dynamics of the neutral clusters. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.476653
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  • 3
    Electronic Resource
    Electronic Resource
    Influence of chaos on the ionization induced fragmentation dynamics of van der Waals clusters (1997)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 107 (1997), S. 9857-9863 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Molecular dynamics simulations based on a self-consistent electronic model are performed to investigate the effect of ionization on the atomic motion of small van der Waals clusters. We find unimolecular dissociation (fragmentation) with time scales in the picosecond range. The dynamics during the relaxation process after ionization turns out to be extremely nonlinear, with fragmentation times which depend strongly on initial conditions. Our calculations show that the largest Liapunov exponent λ+ after ionization is much larger than λ0, the corresponding exponent before ionization. This indicates that the ionization process enhances the nonlinear character of the motion of small clusters. We also determined the distribution of fragmentation times as a function of the vibrational temperature of the clusters before ionization. Since the ionization process creates a state far away from thermodynamical equilibrium, a time-dependent fragmentation probability W(t) is obtained. Furthermore, W(t) reflects the ionization induced chaotic dynamics. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.475283
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  • 4
    Electronic Resource
    Electronic Resource
    Calculation of the electronic properties of neutral and ionized divalent-metal clusters (1993)
    Springer
    The European physical journal 26 (1993), S. 293-295 
    Details
    ISSN: 1434-6079
    Keywords: 36.40+d ; 71.30+h ; 33.80+Eh
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The electronic properties of neutral and ionized divalent-metal clusters have been studied using a microscopic theory, which takes into account the interplay between van der Waals (vdW) and covalent bonding in the neutral clusters, and the competition between hole delocalization and polarization energy in the ionized clusters. By calculating the ground-state energies of neutral and ionized Hg n clusters, we determine the size dependence of the bond character and the ionization potentialI p (n). For neutral Hg n clusters we obtain a transition from van der Waals to covalent behaviour at the critical sizen c ∼10–20 atoms. Results forI p (Hg n ) withn≤20 are in good agreement with experiments, and suggest that small Hg n + clusters can be viewed as consisting of a positive trimer core Hg 3 + surrounded byn−3 polarized neutral atoms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01429173
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  • 5
    Electronic Resource
    Electronic Resource
    On the localization of electrons and holes in Hg n and rare-gas clusters (1994)
    Springer
    The European physical journal 31 (1994), S. 205-207 
    Details
    ISSN: 1434-6079
    Keywords: 36.40. + d ; 71.30. + h ; 33.80. + Eh
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We have used a microscopic theory to study the size dependence of the degree of localization of the valence electrons and holes in neutral an ionized rare-gas-and Hg n clusters. We discuss under which circumstances localization of the electrons and holes is favoured. We have calculated the ionization potential of Xe n , Kr n and small Hg n clusters. Good agreement with experiments is obtained. We have also determined the dependence of the ionization potential on cluster structure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01437837
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  • 6
    Electronic Resource
    Electronic Resource
    On the transition from localized to delocalized electronic states in divalent-metal clusters (1991)
    Springer
    The European physical journal 19 (1991), S. 219-221 
    Details
    ISSN: 1434-6079
    Keywords: 36.40.+d
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The transition from van der Waals to covalent bonding, which is expected to occur in divalent-metal clusters with increasing cluster size, is discussed. We propose a model which takes into account, within the same electronic theory, the three main competing contributions, namely the kinetic energy of the electrons, the Coulomb interactions between electrons, and thes ↔p intraatomic transitions responsible for van der Waals like bonding. The model is solved by taking into account electron correlations using a generalized Gutzwiller approximation (slave boson method). The occurrence of electron localization is studied as a function of the interaction parameters and cluster size.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01448296
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  • 7
    Electronic Resource
    Electronic Resource
    Theory for the optical properties of small Hg n clusters (1991)
    Springer
    The European physical journal 19 (1991), S. 215-217 
    Details
    ISSN: 1434-6079
    Keywords: 33.10 −a ; 31.50. +w
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The static and dynamical polarizabilities of the Hg-dimer are calculated by using a Hubbard Hamiltonian to describe the electronic structure. The Hamiltonian is diagonalized exactly within a subspace of second-quantized electronic states from which only multiply ionized atomic configurations have been excluded. With this approximation we can describe the most important electronic transitions including the effect of charge fluctuations. We analyze the polarizability as a function of the intraatomic Coulomb interaction which represents the repulsion between electrons. We obtain that this interaction results in strong electronic correlations in the excited states and increases the first excitation energy of the dimer by 0.8 eV in comparison to a calculation which neglects correlations, resulting in a better agreement with the experiment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01448295
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  • 8
    Electronic Resource
    Electronic Resource
    Methylmercury(II) complexes with 2-mercaptopyridinecarboxylic acids (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 6 (1992), S. 501-505 
    Details
    ISSN: 0268-2605
    Keywords: Methylmercury ; complexes ; pyridinecarboxylic acids ; stability constants ; mass spectra ; IR spectra ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The stability constants of the complexes [MeHgL]-(H2L = 2-mercaptopyridine-3-carboxylic acid, 2-mercaptopyridine-4-carboxylic acid, 2-mercaptopyridine-5-carboxylic acid and 2-mercaptopyridine-6-carboxylic acid) have been obtained by differential pulse polarography. The values of log β1 are in the range 14.14-14.96 at 20°C and ionic strength 0.1 mol dm-3. The complexes MeHgHL have been isolated and characterized by chemical analysis and mass and IR spectrometry.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aoc.590060605
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  • 9
    Electronic Resource
    Electronic Resource
    Complexes of diorganotin(IV) dihalides with N, N′-dimethyl-2, 2′-bisimidazole (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 7 (1993), S. 421-424 
    Details
    ISSN: 0268-2605
    Keywords: N, N′ -Dimethyl-2, 2′-bisimidazole ; diorganotin(IV) dihalides ; complexes ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Adducts of N, N′ -dimethyl-2, 2′-bisimidazole (DMBIm) with diethyl- and dibutyl-tin(IV) dihalides (Cl, Br) have been isolated and characterized. IR data for [SnR2X2(DMBIm)] compounds are in keeping with a six-coordinate tin atom with DMBIm acting as a bidentate ligand, whereas in [(SnR2X2)2(DMBIm)] the tin is five-coordinate and DMBIm acts as a bridging ligand. Measurements of conductivity in acetonitrile show the adducts to behave as non-ionogens in this solvent. NMR data show them to undergo dissociation in CDCl3.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aoc.590070610
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  • 10
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    A compilation of field surveys on gaseous elemental mercury (GEM) from contrasting environmental settings in Europe, South America, South Africa and China: separating fads from facts (2015)
    Springer Science+Business Media B.V.
    Details
    Publication Date: 2021-06-25
    Description: Mercury is transported globally in the atmosphere mostly in gaseous elemental form (GEM, Hg0 gas), but still few worldwide studies taking into account different and contrasted environmental settings are available in a single publication. This work presents and discusses data from Argentina, Bolivia, Bosnia and Herzegovina, Brazil, Chile, China, Croatia, Finland, Italy, Russia, South Africa, Spain, Slovenia and Venezuela. We classified the information in four groups: (1) mining districts where this contaminant poses or has posed a risk for human populations and/or ecosystems; (2) cities, where the concentration ofatmospheric mercury could be higher than normal due to the burning of fossil fuels and industrial activities; (3) areas with natural emissions from volcanoes; and (4) pristine areas where no anthropogenic influence was apparent. All the surveys were performed using portable LUMEX RA-915 series atomic absorption spectrometers. The results for cities fall within a low GEM concentration range that rarely exceeds 30 ng m-3, that is, 6.6 times lower than the restrictive ATSDR threshold (200 ng m-3) for chronic exposure to this pollutant. We also observed this behavior in the former mercury mining districts, where few data were above 200 ng m-3.We noted that high concentrations of GEM are localized phenomena that fade away in short distances. However, this does not imply that they do not pose a risk for those working in close proximity to the source. This is the case of the artisanal gold miners that heat the Au–Hg amalgam to vaporize mercury. In this respect, while GEM can be truly regarded as a hazard, because of possible physical–chemical transformations into other species, it is only under these localized conditions, implying exposure to high GEM concentrations, which it becomes a direct risk for humans.
    Description: Grants CGL2009-13171 and CTM2012-33918 from the Spanish Ministry of Economy and Competitiveness and PII1I09-0142- 4389 from theCastilla-LaMancha (Spain)RegionalGovernment.
    Description: Published
    Description: 713-734
    Description: 6A. Monitoraggio ambientale, sicurezza e territorio
    Description: JCR Journal
    Description: restricted
    Keywords: Gaseous elemental mercury ; Atmospheric pollution ; Mining districts ; Cities ; Pristine locations ; Volcanos ; Hazards ; Risks ; 05. General::05.08. Risk::05.08.01. Environmental risk
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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