59 research outputs found
New routes in polyoxometalate chemistry : from keplerates to chemistry under confined conditions
No full textTodea AM. New routes in polyoxometalate chemistry : from keplerates to chemistry under confined conditions. Bielefeld (Germany): Bielefeld University; 2008
Assessment of occupational exposure to engineered nanomaterials in research laboratories using personal monitors
No full textExposure assessment is a key stage in the risk assessment/management of engineered nanomaterials. Although different sampling strategies and instruments have been used to define the occupational exposure to nano-scale materials, currently there is no international consensus regarding measurement strategy, metrics and limit values. In fact, the assessment of individual exposure to engineered nanomaterials remains a critical issue despite recent innovative developments in personal monitors and samplers. Hence, we used several of these instruments to evaluate the workers' personal exposure in a large research laboratory where engineered nanomaterials are produced, handled, and characterized in order to provide input data for nanomaterial exposure assessment strategies and future epidemiological studies. The results obtained using personal monitors showed that the workplace concentrations of engineered nanomaterials (lung deposited surface area and particle number concentrations) were quite low in all the different workplaces monitored, with short spikes during the execution of some specific job tasks. The sampling strategy was been adopted on the basis of an Organisation for Economic Cooperation and Development (OECD) suggestion for a tiered approach and was found to be suitable for determining the individual exposure and for identifying possible sources of emission, even those with very low emission rates. The use of these instruments may lead to a significant improvement not only in the exposure assessment stage but, more generally, in the entire risk assessment and management process
Softening of Pore and Interior Properties of a Metal-Oxide-Based Capsule: Substituting 60 Oxide by 60 Sulfide Ligands
No full textSchäffer C, Todea AM, Bögge H, et al. Softening of Pore and Interior Properties of a Metal-Oxide-Based Capsule: Substituting 60 Oxide by 60 Sulfide Ligands. Angewandte Chemie International Edition. 2011;50(51):12326-12329
Spontaneous self-assembly of a giant spherical metal-oxide Keplerate: addition of one building block induces "immediate" formation of the complementary one from a constitutional dynamic library
No full textSchäffer C, Todea AM, Gouzerh P, Müller A. Spontaneous self-assembly of a giant spherical metal-oxide Keplerate: addition of one building block induces "immediate" formation of the complementary one from a constitutional dynamic library. Chemical Communications. 2011;48(3):350-352.The addition of dinuclear Mo(2)} units to a dynamic library containing molybdates results in the spontaneous self-assembly of a giant spherical metal-oxide species of the type (Mo)Mo(5)(12)Mo(2)(30)} while the required pentagonal (Mo)Mo(5) building blocks are "immediately" formed
Metal-oxide-based nucleation process under confined conditions: Two mixed-valence V-6-type aggregates closing the W-48 wheel-type cluster cavities
No full textMüller A, Pope MT, Todea AM, et al. Metal-oxide-based nucleation process under confined conditions: Two mixed-valence V-6-type aggregates closing the W-48 wheel-type cluster cavities. ANGEWANDTE CHEMIE-INTERNATIONAL EDITION. 2007;46(24):4477-4480
Extending the {(Mo)MO5}12M30 capsule keplerate sequence: a {Cr30} cluster of S=3/2 metal centers with a {Na(H2O)12} encapsulate
No full textTodea AM, Merca A, Bögge H, et al. Extending the {(Mo)MO5}12M30 capsule keplerate sequence: a {Cr30} cluster of S=3/2 metal centers with a {Na(H2O)12} encapsulate. Angewandte Chemie. International Edition. 2007;46(32):6106-6110
Triangular geometrical and magnetic motifs uniquely linked on a spherical capsule surface
No full textMüller A, Todea AM, van Slageren J, et al. Triangular geometrical and magnetic motifs uniquely linked on a spherical capsule surface. ANGEWANDTE CHEMIE-INTERNATIONAL EDITION. 2005;44(25):3857-3861
Polyoxotungstates now also with pentagonal units: supramolecular chemistry and tuning of magnetic exchange in {(M)M-5}(12)V-30 Keplerates (M = Mo, W)
No full textTodea AM, Merca A, Bögge H, et al. Polyoxotungstates now also with pentagonal units: supramolecular chemistry and tuning of magnetic exchange in {(M)M-5}(12)V-30 Keplerates (M = Mo, W). Chemical Communications. 2009;(23):3351-3353.The deliberate synthesis of the Keplerate [K-20 subset of {(W)W5O21(SO4)}(12)(VO)(30)(SO4)(H2O)(63)](18-) 1a with 20 pores all closed by K+ in a supramolecular fashion proves that it is possible to follow new routes in polyoxotungstate chemistry based on pentagonal {(W)W-5}-type units and to tune magnetic exchange couplings in {(M)M-5}(12)M'(30) type Keplerates
The imperfect - preterite opposition in romance languages
No full textAn aspect of the Romance languages that defies neat linguistic analysis is tense usage. In particular, students of Romance languages as well as grammarians have found it difficult to provide a consistent explanation for the imperfect - preterite opposition. Two main points of contention concern (i) the question of whether the two forms have an inherent aspectual content and (ii) the structure and role of lexical aspectual information in determining the overall meaning of a sentence. While the attempts at explaining French and Spanish usages of the imperfect and the preterite are numerous, hardly any work has been done in the interpretation of Romanian data. Furthermore, a general assumption that the same form - function opposition holds across Romance languages has led to cross-linguistic differences rarely being examined. I argue that the imperfect and the preterite do have an inherent aspectual content. However, in opposition to previous accounts, I maintain that the preterite does not provide a ‘closed’ viewpoint and that an atelic eventuality described by the verb phrase in the preterite can continue up to the present moment. I propose a description of the imperfect - preterite opposition that includes finer distinctions of lexical aspect based on its constituent stage structure. These finer lexical aspectual distinctions allow the identification of an area of divergence in the use of the two forms in French, Spanish, and Romanian: the preterite was found to be used more widely with states in Romanian than in French and Spanish
- …
