31 research outputs found

    Mn12_{12}-Acetate Complexes Studied as Single Molecules

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    The phenomenon of single molecule magnet (SMM) behavior of mixed valent Mn12 coordination clusters of general formula [MnIII^{III}8_{8}MnIV^{IV}4_{4}O12_{12}(RCOO)16_{16}(H2_{2}O)4_{4}] had been exemplified by bulk samples of the archetypal [MnIII^{III}8_{8}MnIV^{IV}4_{4}O12_{12}(CH3_{3}COO)16_{16}(H2_{2}O)4_{4}] (4) molecule, and the molecular origin of the observed magnetic behavior has found support from extensive studies on the Mn12 system within crystalline material or on molecules attached to a variety of surfaces. Here we report the magnetic signature of the isolated cationic species [Mn12_{12}O12_{12}(CH3_{3}COO)15_{15}(CH3_{3}CN)]+^{+} (1) by gas phase X-ray Magnetic Circular Dichroism (XMCD) spectroscopy, and we find it closely resembling that of the corresponding bulk samples. Furthermore, we report broken symmetry DFT calculations of spin densities and single ion tensors of the isolated, optimized complexes [Mn12_{12}O12_{12}(CH3_{3}COO)15_{15}(CH3_{3}CN)]+^{+} (1), [[Mn12_{12}O12_{12}(CH3_{3}COO)16_{16}] (2), [Mn12_{12}O12_{12}(CH3_{3}COO)16_{16}(H2_{2}O)4_{4}] (3), and the complex in bulk geometry [MnIII^{III}8_{8}MnIV^{IV}4_{4}O12_{12}(CH3_{3}COO)16_{16}(H2_{2}O)4_{4}] (5). The found magnetic fingerprints – experiment and theory alike – are of a remarkable robustness: The MnIV^{IV}4_{4} core bears almost no magnetic anisotropy while the surrounding MnIII8 ring is highly anisotropic. These signatures are truly intrinsic properties of the Mn12_{12} core scaffold within all of these complexes and largely void of the environment. This likely holds irrespective of bulk packing effects

    Landscape structure, human disturbance and crop management affect foraging ground selection by migrating geese

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    It is well known that agricultural intensification has caused severe population declines among bird species which use farmland for breeding and overwintering, while migrating bird species may benefit from intensive farming, but in turn damage crops. Knowledge of the habitat selection of migrating birds is important from both a conservation and agro-economic point of view. We investigated the habitat preferences of three common migrating goose species: White-fronted Goose Anser albifrons, Bean Goose A. fabalis and Greylag Goose A. anser during the autumn of 2009 in western Poland. A total of 24 flocks of these species were identified. Geese preferred large, elevated fields that were remote from forests and human settlements but in close proximity to a lake. Geese selected maize stubbles and avoided winter cereals. They selected sites in landscapes with a lower diversity of crops. Flock size was negatively correlated with the proportion of pastures in the landscape, but it increased with field size, distance to forest and distance to town. Our results are in contrast with the paradigm that less intensive farmland positively influences habitat use by birds during foraging. We advise the delayed ploughing of stubbles with the aim of creating appropriate foraging habitats for geese and minimizing damage to cereal crops

    Fluoride concentrations in the pineal gland, brain and bone of goosander (Mergus merganser) and its prey in Odra River estuary in Poland

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    AML multi-gene panel testing: A review and comparison of two gene panels

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    © 2016 Elsevier GmbH. Background/objective: Risk adapted therapy is standard practice in Acute Myeloid Leukemia (AML). A common diagnostic approach involves focusing on a three gene panel (CEPBA, FLT3, and NPM1). However, a complete representation of prognostic and predictive factors in AML necessitates an expanded series of genes, due to the dynamic interactions present between concurrent mutations. Hence, the current study aims to describe the benefits of an expanded risk profile in an unselected cohort of AML cases. Methods: The genomes of 11 randomly selected patients with AML were sequenced using next generation sequencing. A narrow three gene panel and broader 50 gene panel were contrasted. Results: The expanded gene panel detected one additional pathogenic mutation in five patients and two pathogenic mutations in two patients, resulting in a change in their risk profile. Only 5/11 (45%) of AML patients demonstrated a pathogenic mutation on the 3 gene profile, however all patients had at least one detectable pathogenic mutation on the broader gene panel. The detection of a concurrent mutation by the expanded gene panel reversed the favorable risk profile for three patients. Conclusions: Detection of concurrent mutations enables rejection or validation of prognoses associated with NPM1 or CEBPA mutations. DNMT3a and TP53 mutations in AML have a pertinent prognostic and therapeutic value for patients and their addition enhances the current three gene panel. In our small study, the three gene panel changed the prognosis for three patients (3/11, 27%) with the detection of commonly occurring AML mutations

    Multiple ionization and fragmentation of isolated pyrene and coronene molecules in collision with ions

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    International audienceThe interaction of multiply charged ions (He2+, O3+, and Xe20+) with gas-phase pericondensed polycyclic aromatic hydrocarbon (PAH) molecules of coronene (C24H12) and pyrene (C16H10) is studied for low-velocity collisions (v ≤ 0.6 a.u.). The mass spectrometric analysis shows that singly and up to quadruply charged intact molecules are important reaction products. The relative experimental yields are compared with the results of a simple classical over-the-barrier model. For higher molecular charge states, the experimental yields decrease much more strongly than the model predictions due to the instabilities of the multiply charged PAH molecules. Even-odd oscillations with the number of carbon atoms, n, in the intensity distributions of the CnHx+ fragments indicate a linear chain structure of the fragments similar to those observed for ion-C60 collisions. The latter oscillations are known to be due to dissociation energy differences between even- and odd-n Cn-chain molecules. For PAH molecules, the average numbers of H atoms attached to the CnHx chains are larger for even-n reflecting acetylenic bond systems
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