100 research outputs found
Electron-phonon effects and transport in carbon nanotubes
We calculate the electron-phonon scattering and binding in semiconducting
carbon nanotubes, within a tight binding model. The mobility is derived using a
multi-band Boltzmann treatment. At high fields, the dominant scattering is
inter-band scattering by LO phonons corresponding to the corners K of the
graphene Brillouin zone. The drift velocity saturates at approximately half the
graphene Fermi velocity. The calculated mobility as a function of temperature,
electric field, and nanotube chirality are well reproduced by a simple
interpolation formula. Polaronic binding give a band-gap renormalization of ~70
meV, an order of magnitude larger than expected. Coherence lengths can be quite
long but are strongly energy dependent.Comment: 5 pages and 4 figure
Unconventional ferromagnetic and spin-glass states of the reentrant spin glass Fe0.7Al0.3
Spin excitations of single crystal Fe0.7Al0.3 were investigated over a wide
range in energy and reciprocal space with inelastic neutron scattering. In the
ferromagnetic phase, propagating spin wave modes become paramagnon-like
diffusive modes beyond a critical wave vector q0, indicating substantial
disorder in the long-range ordered state. In the spin glass phase, spin
dynamics is strongly q-dependent, suggesting remnant short-range spin
correlations. Quantitative model for S(energy,q) in the ``ferromagnetic'' phase
is determined.Comment: 4 pages, 5 figure
First assessment of the comparative toxicity of ivermectin and moxidectin in adult dung beetles: Sub-lethal symptoms and pre-lethal consequences
Among macrocyclic lactones (ML), ivermectin (IVM) and moxidectin (MOX) potentially affect all
Ecdysozoan species, with dung beetles being particularly sensitive. The comparative effects of IVM
and MOX on adult dung beetles were assessed for the first time to determine both the physiological
sub-lethal symptoms and pre-lethal consequences. Inhibition of antennal response and ataxia
were tested as two intuitive and ecologically relevant parameters by obtaining the lowest observed
effect concentration (LOEC) values and interpolating other relevant toxicity thresholds derived from
concentration-response curves (IC50, as the concentration of each ML where the antennal response is
inhibited by half; and pLC50, as the quantity of ingested ML where partial paralysis was observed by half
of treated individuals) from concentration-response curves. Both sub-lethal and pre-lethal symptoms
obtained in this study coincided in that IVM was six times more toxic than MOX for adult dung beetles.
Values of LOEC, IC50 and pLC50 obtained for IVM and MOX evaluated in an environmental context
indicate that MOX, despite needing more time for its elimination in the faeces, would be half as harmful
to dung beetles as IVM. This approach will be valuable to clarify the real impact of MLs on dung beetle
health and to avoid the subsequent environmental consequences
Macrocheles species (Acari: Macrochelidae) associated with human corpses in Europe
The biology of macrochelid mites might offer new venues for the interpretation of the environmental conditions surrounding human death and decomposition. Three human corpses, one from Sweden and two from Spain, have been analysed for the occurrence of Macrochelidae species.
Macrocheles muscaedomesticae females were associated with a corpse that was found in a popular beach area of southeast Spain. Their arrival coincides with the occurrence of one of their major carrier species, the filth fly Fannia scalaris, the activity of which peaks during mid-summer. M. glaber specimens were collected from a corpse in a shallow grave in a forest in Sweden at the end of summer, concurrent with the arrival of beetles attracted by odours from the corpse. M. perglaber adults were sampled from a corpse found indoors in the rural surroundings of Granada city, Spain. The phoretic behaviour of this species is similar to that of M. glaber, but being more specific to Scarabaeidae and Geotrupidae dung beetles, most of which favour human faeces.
M. muscaedomesticae is known from urban and rural areas and poultry farms; M. glaber from outdoors, particularly the countryside; while M. perglaber from outdoor, rural, and remote, potentially mountainous locations.
M. muscaedomesticae and M. perglaber are reported for the first time from the Iberian Peninsula. This is the first record of M. perglaber from human remains
Macrocheles species (Acari: Macrochelidae) associated with human corpses in Europe
The biology of macrochelid mites might offer new venues for the interpretation of the environmental conditions surrounding human death and decomposition. Three human corpses, one from Sweden and two from Spain, have been analysed for the occurrence of Macrochelidae species.
Macrocheles muscaedomesticae females were associated with a corpse that was found in a popular beach area of southeast Spain. Their arrival coincides with the occurrence of one of their major carrier species, the filth fly Fannia scalaris, the activity of which peaks during mid-summer. M. glaber specimens were collected from a corpse in a shallow grave in a forest in Sweden at the end of summer, concurrent with the arrival of beetles attracted by odours from the corpse. M. perglaber adults were sampled from a corpse found indoors in the rural surroundings of Granada city, Spain. The phoretic behaviour of this species is similar to that of M. glaber, but being more specific to Scarabaeidae and Geotrupidae dung beetles, most of which favour human faeces.
M. muscaedomesticae is known from urban and rural areas and poultry farms; M. glaber from outdoors, particularly the countryside; while M. perglaber from outdoor, rural, and remote, potentially mountainous locations.
M. muscaedomesticae and M. perglaber are reported for the first time from the Iberian Peninsula. This is the first record of M. perglaber from human remains
Purification and characterization of (1-]3, 1-]4)-beta-gluca endohydrolases from germinated wheat (Triticum aestivum)
A (1→3, 1→4)-β-glucan 4-glucanohydrolase [(1→3, 1→4)-β-glucanase, EC 3.2.1.73] was purified to homogeneity from extracts of germinated wheat grain. The enzyme, which was identified as an endohydrolase on the basis of oligosaccharide products released from a (1→3, 1→4)-β-glucan substrate, has an apparent pI of 8.2 and an apparent molecular mass of 30 kDa. Western blot analyses with specific monoclonal antibodies indicated that the enzyme is related to (1→3, 1→4)-β-glucanase isoenzyme EI from barley. The complete primary structure of the wheat (1→3, 1→4)-β-glucanase has been deduced from nucleotide sequence analysis of cDNAs isolated from a library prepared using poly(A)+ RNA from gibberellic acid-treated wheat aleurone layers. One cDNA, designated λLW2, is 1426 nucleotide pairs in length and encodes a 306 amino acid enzyme, together with a NH2-terminal signal peptide of 28 amino acid residues. The mature polypeptide encoded by this cDNA has a molecular mass of 32085 and a predicted pI of 8.1. The other cDNA, designated λLW1, carries a 109 nucleotide pair sequence at its 5′ end that is characteristic of plant introns and therefore appears to have been synthesized from an incompletely processed mRNA. Comparison of the coding and 3′-untranslated regions of the two cDNAs reveals 31 nucleotide substitutions, but none of these result in amino acid substitutions. Thus, the cDNAs encode enzymes with identical primary structures, but their corresponding mRNAs may have originated from homeologous chromosomes in the hexaploid wheat genome
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