87 research outputs found
Resonant soft X-ray Raman scattering of NiO
Resonant soft X-ray Raman scattering measurements on NiO have been made at
photon energies across the Ni 2p absorption edges. The details of the spectral
features are identified as Raman scattering due to d-d and charge-transfer
excitations. The spectra are interpreted within the single impurity Anderson
model, including multiplets, crystal-field and charge-transfer effects. At
threshold excitation, the spectral features consists of triplet-triplet and
triplet-singlet transitions of the 3d8 configuration. For excitation energies
corresponding to the charge-transfer region in the Ni 2p X-ray absorption
spectrum of NiO, the emission spectra are instead dominated by charge-transfer
transitions to the 3d9L-1 final state. Comparisons of the final states with
other spectroscopical techniques are also made.Comment: 9 pages, 2 figures, 2 tables,
http://iopscience.iop.org/0953-8984/14/13/32
Volatiles from Maruca vitrata (Lepidoptera, Crambidae) host plants influence olfactory responses of the parasitoid Therophilus javanus (Hymenoptera, Braconidae, Agathidinae)
Open Access Article; Published online: 9 Nov 2018.Plants damaged by herbivores are known to release odors attracting parasitoids. However, there is currently no information how leguminous plants damaged by the pod borer Maruca vitrata attract the exotic larval parasitoid Therophilus javanus, which was imported into Benin from the putative area of origin of the pod borer in tropical Asia for assessing its potential as a biological control agent. In this study, we used Y-tube olfactometer bioassays to investigate T. javanus response towards odors emitted by four M. vitrata-damaged host plants: cowpea Vigna unguiculata, the most important cultivated host, and the naturally occurring legumes Lonchocarpus sericeus, Sesbania rostrata and Tephrosia platycarpa. Olfactory attraction of T. javanus was influenced by the species of plant damaged by the pod borer. Moreover, odors released from M. vitrata-infested host plant organs (flowers and pods) were discriminated over non-infested organs in cowpea and T. platycarpa, respectively. These results are discussed in the context of the possible impact of M. vitrata host plants on T. javanus foraging activity and subsequent establishment in natural environments following experimental releases
Resonant inelastic soft-x-ray scattering spectra at the N1s and C1s edges of poly(pyridine-2,5-diyl)
Resonant inelastic scattering measurements of poly(pyridine-2,5-diyl) have
been performed at the N1s and C1s edges using synchrotron radiation. For
comparison, molecular orbital calculations of the spectra have been carried out
with the repeat unit as a model molecule of the polymer chain. The resonant
emission spectra show depletion of the p electron bands which is consistent
with symmetry selection and momentum conservation rules. The depletion is most
obvious in the resonant inelastic scattering spectra of carbon while the
nitrogen spectra are dominated by lone pair n orbital emission of s symmetry
and are less excitation energy dependent. By comparing the measurements to
calculations an isomeric dependence of the resonant spectra is found giving
preference to two of the four possible isomers in the polymer.Comment: 6 pages, 3 figures,
http://www.sciencedirect.com/science/article/pii/S036820489800354
The electronic structure of poly(pyridine-2,5-diyl) investigated by soft x-ray absorption and emission spectroscopies
The electronic structure of the poly-pyridine conjugated polymer has been
investigated by resonant and nonresonant inelastic X-ray scattering and X-ray
absorption spectroscopies using synchrotron radiation. The measurements were
made for both the carbon and nitrogen contents of the polymer. The analysis of
the spectra has been carried out in comparison with molecular orbital
calculations taking the repeat-unit cell as a model molecule of the polymer
chain. The simulations indicate no significant differences in the absorption
and in the non-resonant X-ray scattering spectra for the different isomeric
geometries, while some isomeric dependence of the resonant spectra is
predicted. The resonant emission spectra show depletion of the {\pi} electron
bands in line with symmetry selection and momentum conservation rules. The
effect is most vizual for the carbon spectra; the nitrogen spectra are
dominated by lone pair n orbital emission of {\sigma} symmetry and are less
frequency dependent.Comment: 11 pages, 7 figures, 1 table,
http://www.sciencedirect.com/science/article/pii/S030101049800262
Genetic Background Strongly Modifies the Severity of Symptoms of Hirschsprung Disease, but Not Hearing Loss in Rats Carrying Ednrbsl Mutations
Hirschsprung disease (HSCR) is thought to result as a consequence of multiple gene interactions that modulate the ability of enteric neural crest cells to populate the developing gut. However, it remains unknown whether the single complete deletion of important HSCR-associated genes is sufficient to result in HSCR disease. In this study, we found that the null mutation of the Ednrb gene, thought indispensable for enteric neuron development, is insufficient to result in HSCR disease when bred onto a different genetic background in rats carrying Ednrbsl mutations. Moreover, we found that this mutation results in serious congenital sensorineural deafness, and these strains may be used as ideal models of Waardenburg Syndrome Type 4 (WS4). Furthermore, we evaluated how the same changed genetic background modifies three features of WS4 syndrome, aganglionosis, hearing loss, and pigment disorder in these congenic strains. We found that the same genetic background markedly changed the aganglionosis, but resulted in only slight changes to hearing loss and pigment disorder. This provided the important evidence, in support of previous studies, that different lineages of neural crest-derived cells migrating along with various pathways are regulated by different signal molecules. This study will help us to better understand complicated diseases such as HSCR and WS4 syndrome
Multigenic control of resistance to Sendai virus infection in mice
Experimental infection of mice with Sendai virus (SeV) is frequently used as a model of viral pathogenesis of human respiratory disease. To understand the differences in host response to SeV among mice strains, we carried out genetic mapping studies in DBA/2 (D2) (susceptible) and C57BL/6 (B6) (resistant) mice. F1, F2, and N2 backcrossed mice were generated and examined for their disease resistance and susceptibility. For the determination of virulence, percentage body weight loss and survival time were used as phenotypes. We, then, carried out a genome wide scan on 108 backcrossed mice for linkage with percentage body weight loss as phenotype. A major quantitative trait locus (QTL) showing significant linkage was mapped to the distal portion of Chr4 (SeV1). In addition, two other QTLs showing suggestive statistical linkage were also detected on Chr 8 and 14. We, further, performed genome scan for interactions with least squares analysis of variance of all pairs of informative makers in backcrossed progenies. We identified a highly significant epistatic interaction between D3Mit182 and D14Mit10, then denoted as SeV2 and SeV3, respectively, and the latter was the same locus showing a suggestive level on Chr 14 in QTL analysis. Considered genotypes of these three loci, we could account for more than 90% of genetic effect on the differential response to SeV infection between B6 and D2 mice. These findings revealed a novel gene interactions controlling SeV resistance in mice and will enable the identification of resistance genes encoded within these loci
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