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

Local distortion in LaCoO3 and PrCoO3: EXAFS, XRD and XANES studies

Room temperature Co K-edge extended x-ray absorption fine structure (EXAFS), x-ray absorption near edge structure (XANES) including pre-edge and x-ray diffraction (XRD) studies are carried out on LaCoO3 and PrCoO3. The Co-O, Co-La/Pr and Co-Co bond lengths are obtained from EXAFS analysis and compared with those obtained from XRD. The EXAFS analysis of data indicates that CoO6 octahedron is distorted in both LaCoO3 and PrCoO3. Such distortion is expected in orthorhombic PrCoO3 but not in rhombohedral LaCoO3. This distortion in CoO6 octahedron is attributed to Jahn-Teller active Co3+ ion in intermediate spin state in these compounds. Higher shell studies reveal that Debye-Waller (DW) factors of Co-Pr and Co-Co bonds in PrCoO3 are more in comparison to Co-La and Co-Co bonds in LaCoO3 indicating that these bonds are structurally more disordered in PrCoO3. The comparison of Co-Co bond lengths and corresponding DW factors indicates that the structural disorder plays an important role in deciding the insulating properties of these compounds. XANES studies have shown changes in the intensities and positions of different near edge features.Comment: 22 pages, 8 figures, 2 tables. To appear in J. Phys.: Condens. Matte

Deconvolving Instrumental and Intrinsic Broadening in Excited State X-ray Spectroscopies

Intrinsic and experimental mechanisms frequently lead to broadening of spectral features in excited-state spectroscopies. For example, intrinsic broadening occurs in x-ray absorption spectroscopy (XAS) measurements of heavy elements where the core-hole lifetime is very short. On the other hand, nonresonant x-ray Raman scattering (XRS) and other energy loss measurements are more limited by instrumental resolution. Here, we demonstrate that the Richardson-Lucy (RL) iterative algorithm provides a robust method for deconvolving instrumental and intrinsic resolutions from typical XAS and XRS data. For the K-edge XAS of Ag, we find nearly complete removal of ~9.3 eV FWHM broadening from the combined effects of the short core-hole lifetime and instrumental resolution. We are also able to remove nearly all instrumental broadening in an XRS measurement of diamond, with the resulting improved spectrum comparing favorably with prior soft x-ray XAS measurements. We present a practical methodology for implementing the RL algorithm to these problems, emphasizing the importance of testing for stability of the deconvolution process against noise amplification, perturbations in the initial spectra, and uncertainties in the core-hole lifetime.Comment: 35 pages, 13 figure

Effects of exposure to water disinfection by-products in a swimming pool: A metabolome-wide association study

BACKGROUND: Exposure to disinfection by-products (DBPs) in drinking water and chlorinated swimming pools are associated with adverse health outcomes, but biological mechanisms remain poorly understood. OBJECTIVES: Evaluate short-term changes in metabolic profiles in response to DBP exposure while swimming in a chlorinated pool. MATERIALS AND METHODS: The PISCINA-II study (EXPOsOMICS project) includes 60 volunteers swimming 40min in an indoor pool. Levels of most common DBPs were measured in water and in exhaled breath before and after swimming. Blood samples, collected before and 2h after swimming, were used for metabolic profiling by liquid-chromatography coupled to high-resolution mass-spectrometry. Metabolome-wide association between DBP exposures and each metabolic feature was evaluated using multivariate normal (MVN) models. Sensitivity analyses and compound annotation were conducted. RESULTS: Exposure levels of all DBPs in exhaled breath were higher after the experiment. A total of 6,471 metabolic features were detected and 293 features were associated with at least one DBP in exhaled breath following Bonferroni correction. A total of 333 metabolic features were associated to at least one DBP measured in water or urine. Uptake of DBPs and physical activity were strongly correlated and mutual adjustment reduced the number of statistically significant associations. From the 293 features, 20 could be identified corresponding to 13 metabolites including compounds in the tryptophan metabolism pathway. CONCLUSION: Our study identified numerous molecular changes following a swim in a chlorinated pool. While we could not explicitly evaluate which experiment-related factors induced these associations, molecular characterization highlighted metabolic features associated with exposure changes during swimming

Electronic structure investigation of CoO by means of soft X-ray scattering

The electronic structure of CoO is studied by resonant inelastic soft X-ray scattering spectroscopy using photon energies across the Co 2p absorption edges. The different spectral contributions from the energy-loss structures are identified as Raman scattering due to d-d and charge-transfer excitations. For excitation energies close to the L3 resonance, the spectral features are dominated by quartet-quartet and quartet-doublet transitions of the 3d7 configuration. At excitation energies corresponding to the satellites in the Co 2p X-ray absorption spectrum of CoO, the emission features are instead dominated by charge-transfer transitions to the 3d8L-1 final state. The spectra are interpreted and discussed with the support of simulations within the single impurity Anderson model with full multiplet effects which are found to yield consistent spectral functions to the experimental data.Comment: 8 pages, 2 figures, 2 tables, http://link.aps.org/doi/10.1103/PhysRevB.65.20510

Cord blood epigenome-wide meta-analysis in six European-based child cohorts identifies signatures linked to rapid weight growth

BACKGROUND: Rapid postnatal growth may result from exposure in utero or early life to adverse conditions and has been associated with diseases later in life and, in particular, with childhood obesity. DNA methylation, interfacing early-life exposures and subsequent diseases, is a possible mechanism underlying early-life programming. METHODS: Here, a meta-analysis of Illumina HumanMethylation 450K/EPIC-array associations of cord blood DNA methylation at single CpG sites and CpG genomic regions with rapid weight growth at 1 year of age (defined with reference to WHO growth charts) was conducted in six European-based child cohorts (ALSPAC, ENVIRONAGE, Generation XXI, INMA, Piccolipiù, and RHEA, N = 2003). The association of gestational age acceleration (calculated using the Bohlin epigenetic clock) with rapid weight growth was also explored via meta-analysis. Follow-up analyses of identified DNA methylation signals included prediction of rapid weight growth, mediation of the effect of conventional risk factors on rapid weight growth, integration with transcriptomics and metabolomics, association with overweight in childhood (between 4 and 8 years), and comparison with previous findings. RESULTS: Forty-seven CpGs were associated with rapid weight growth at suggestive p-value <1e-05 and, among them, three CpGs (cg14459032, cg25953130 annotated to ARID5B, and cg00049440 annotated to KLF9) passed the genome-wide significance level (p-value <1.25e-07). Sixteen differentially methylated regions (DMRs) were identified as associated with rapid weight growth at false discovery rate (FDR)-adjusted/Siddak p-values < 0.01. Gestational age acceleration was associated with decreasing risk of rapid weight growth (p-value = 9.75e-04). Identified DNA methylation signals slightly increased the prediction of rapid weight growth in addition to conventional risk factors. Among the identified signals, three CpGs partially mediated the effect of gestational age on rapid weight growth. Both CpGs (N=3) and DMRs (N=3) were associated with differential expression of transcripts (N=10 and 7, respectively), including long non-coding RNAs. An AURKC DMR was associated with childhood overweight. We observed enrichment of CpGs previously reported associated with birthweight. CONCLUSIONS: Our findings provide evidence of the association between cord blood DNA methylation and rapid weight growth and suggest links with prenatal exposures and association with childhood obesity providing opportunities for early prevention

Relativistic theory of magnetic scattering of x rays: Application to ferromagnetic iron

We present a detailed description of a first-principles formalism for magnetic scattering of circularly polar- ized x rays from solids in the framework of the fully relativistic spin-polarized multiple-scattering theory. The scattering amplitudes are calculated using a standard time-dependent perturbation theory to second order in the electron-photon interaction vertex. Particular attention is paid to understanding the relative importance of the positive- and negative-energy solutions of the Dirac equation to the scattering amplitude. The advantage of the present theory as compared with other recent works on magnetic x-ray scattering is that, being fully relativistic, spin-orbit coupling and spin-polarization effects are treated on an equal footing. Second, the electron Green’s function expressed in terms of the path operators in the multiple-scattering theory allows us to include the contribution of the crystalline environment to the scattering amplitude. To illustrate the use of the method we have done calculations on the anomalous magnetic scattering at the K , L_II , and L_III absorption edges of ferromagnetic iron

Relativistic Calculation of two-Electron one-Photon and Hypersatellite Transition Energies for 12≤Z≤3012\leq Z\leq30 Elements

Energies of two-electron one-photon transitions from initial double K-hole states were computed using the Dirac-Fock model. The transition energies of competing processes, the K$\alpha$ hypersatellites, were also computed. The results are compared to experiment and to other theoretical calculations.Comment: accepted versio

Problematic mukbang watching and its relationship to disordered eating and internet addiction: a pilot study among emerging adult mukbang watchers

Internet technology has facilitated the use of a wide variety of different activities and applications in online contexts. One such activity is watching mukbang (i.e., watching videos of “eating broadcasts” where someone eats a large amount of food while interacting with viewers). In the present study, the relationship of problematic mukbang watching with disordered eating and internet addiction was examined. Participants were 140 emerging adults who watched mukbang at least once in the past 30 days (66% female; Mage = 21.66, SD = 1.88, range = 19–29 years). Structural equation modeling indicated that problematic mukbang watching was positively associated with both disordered eating and internet addiction. The present study is the first to explore the predictive role of problematic mukbang watching on adverse consequences, and suggests that mukbang watching may be problematic for a minority of emerging adults and that problematic mukbang watching warrants further examination of its impact on mental health and wellbeing