Liquid chromatography–mass spectrometry analysis of cationic aniline dyes from the Technical University of Dresden Historical Collection of Dyes

Open Access via the Jisc Sage Agreement Acknowledgements We are grateful to Prof. Dr. Horst Hartmann of the Historische Farbstoffsammlung, Technische Universität Dresden and to the Chandler museum, New York, for samples to analyse. Declaration of conflicting interests The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article. Funding The author(s) received no financial support for the research, authorship, and/or publication of this article.Peer reviewedPublisher PD

Low-temperature lattice effects in the spin-liquid candidate κ\kappa-(BEDT-TTF)2_2Cu2_2(CN)3_3

The quasi-two-dimensional organic charge-transfer salt $\kappa$-(BEDT-TTF)$_2$Cu$_2$(CN)$_3$ is one of the prime candidates for a quantum spin-liquid due the strong spin frustration of its anisotropic triangular lattice in combination with its proximity to the Mott transition. Despite intensive investigations of the material's low-temperature properties, several important questions remain to be answered. Particularly puzzling are the 6\,K anomaly and the enigmatic effects observed in magnetic fields. Here we report on low-temperature measurements of lattice effects which were shown to be particularly strongly pronounced in this material (R. S. Manna \emph{et al.}, Phys. Rev. Lett. \textbf{104}, 016403 (2010)). A special focus of our study lies on sample-to-sample variations of these effects and their implications on the interpretation of experimental data. By investigating overall nine single crystals from two different batches, we can state that there are considerable differences in the size of the second-order phase transition anomaly around 6\,K, varying within a factor of 3. In addition, we find field-induced anomalies giving rise to pronounced features in the sample length for two out of these nine crystals for temperatures $T <$ 9 K. We tentatively assign the latter effects to $B$-induced magnetic clusters suspected to nucleate around crystal imperfections. These $B$-induced effects are absent for the crystals where the 6\,K anomaly is most strongly pronounced. The large lattice effects observed at 6\,K are consistent with proposed pairing instabilities of fermionic excitations breaking the lattice symmetry. The strong sample-to-sample variation in the size of the phase transition anomaly suggests that the conversion of the fermions to bosons at the instability is only partial and to some extent influenced by not yet identified sample-specific parameters

Far-Ultraviolet H_2 Emission from Circumstellar Disks

We analyze the far-ultraviolet (FUV) spectra of 33 classical T Tauri stars (CTTS), including 20 new spectra obtained with the Advanced Camera for Surveys Solar Blind Channel (ACS/SBC) on the Hubble Space Telescope. Of the sources, 28 are in the ~1 Myr old Taurus-Auriga complex or Orion Molecular Cloud, 4 in the 8-10 Myr old Orion OB1a complex, and 1, TW Hya, in the 10 Myr old TW Hydrae Association. We also obtained FUV ACS/SBC spectra of 10 non-accreting sources surrounded by debris disks with ages between 10 and 125 Myr. We use a feature in the FUV spectra due mostly to electron impact excitation of H_2 to study the evolution of the gas in the inner disk. We find that the H_2 feature is absent in non-accreting sources, but is detected in the spectra of CTTS and correlates with accretion luminosity. Since all young stars have active chromospheres which produce strong X-ray and UV emission capable of exciting H_2 in the disk, the fact that the non-accreting sources show no H_2 emission implies that the H_2 gas in the inner disk has dissipated in the non-accreting sources, although dust (and possibly gas) remains at larger radii. Using the flux at 1600 Å, we estimate that the column density of H_2 left in the inner regions of the debris disks in our sample is less than ~3 × 10^(–6) g cm^(-2), 9 orders of magnitude below the surface density of the minimum mass solar nebula at 1 AU

GRB Repetition Limits from Current BATSE Observations

Revised upper limits on gamma-ray burst repetition rates are found using the BATSE 3B and 4B catalogs. A statistical repetition model is assumed in which sources burst at a mean rate but in which BATSE observes bursts randomly from each source

Developing Methods to Evaluate Phenotypic Variability in Biological Nitrification Inhibition (BNI) Capacity of \u3cem\u3eBrachiaria\u3c/em\u3e Grasses

As part of the nitrogen (N) cycle in the soil, nitrification is an oxidation process mediated by microorganisms that transform the relatively immobile ammonium (NH4+)to the water soluble nitrate (NO3-), enabling the production of nitrous oxide (N2O, a potent greenhouse gas) by denitrification as a by-product (Canfield et al. 2010). Researchers at CIAT-Colombia in collaboration with JIRCAS-Japan, reported that Brachiaria humidicola forage grasses have the ability to inhibit the nitrification process by exuding chemical compounds from its roots to the soil. A major hydrophobic compound was discovered and named brachial-actone (Subbarao et al. 2009). This capacity of Brachiaria grasses is known as biological nitrification inhibition (BNI) and it could contribute to better N use efficiency in crop-livestock systems by improving recovery of applied N while reducing NO3- leaching and N2O emission. The current methodologies for quantifying the BNI trait need further improvement to facilitate high throughput evaluation to quantify genotypic differences. In this paper, we aim to develop new (or improve the existing) phenotyping methods for this trait. Preliminary results were obtained using three different methods to quantify BNI: (1) a mass spectrometry method to quantify brachialactone; (2) a static chamber method to quantify N2O emission from soils under greenhouse conditions; and (3) an improved molecular method to quantify microbial populations by Real-Time PCR. Using these three methods we expect to score a bi-parental hybrid population (n=134) of two B. humidicola accessions differing in their BNI capacity CIAT26146 (medium to low BNI) x CIAT16888 (high BNI), in an attempt to identify QTLs associated with the BNI trait

Testing the Dipole and Quadrupole Moments of Galactic Models

If gamma-ray bursts originate in the Galaxy, at some level there should be a galactic pattern in their distribution on the sky. We test published galactic models by comparing their dipole and quadrupole moments with the moments of the BATSE 3B catalog. While many models have moments that are too large, several models are in acceptable or good agreement with the data.Comment: 5 pages, LaTex using Revtex macro aipbook.sty and psfig. To appear in the Proceedings of the 3rd Huntsville Symposium on Gamma-Ray Bursts, AIP, eds. C. Kouveliotou, M. S. Briggs, G. J. Fishma

The Initial Mass Function and Disk Frequency of the Rho Ophiuchi Cloud: An Extinction-Limited Sample

We have completed an optical spectroscopic survey of an unbiased, extinction-limited sample of candidate young stars covering 1.3 square degrees of the Rho Ophiuchi star forming region. While infrared, X-ray, and optical surveys of the cloud have identified many young stellar objects (YSOs), these surveys are biased towards particular stages of stellar evolution and are not optimal for studies of the disk frequency and initial mass function.We have obtained over 300 optical spectra to help identify 135 association members based on the presence of H-alpha in emission, lithium absorption, X-ray emission, a mid-infrared excess, a common proper motion, reflection nebulosity, and/or extinction considerations. Spectral types along with R and I band photometry were used to derive effective temperatures and bolometric luminosities for association members to compare with theoretical tracks and isochrones for pre-main-sequence stars. An average age of 3.1 Myr is derived for this population which is intermediate between that of objects embedded in the cloud core of Rho Ophiuchi and low mass stars in the Upper Scorpius subgroup. Consistent with this age we find a circumstellar disk frequency of 27% plus or minus 5%. We also constructed an initial mass function for an extinction-limited sample of 123 YSOs (A_v less than or equal to 8 mag), which is consistent with the field star initial mass function for YSOs with masses > 0.2 M_sun. There may be a deficit of brown dwarfs but this result relies on completeness corrections and requires confirmation.Comment: 46 pages, 7 figures, 4 table

Effect of the strain Bacillus amyloliquefaciens FZB42 on the microbial community in the rhizosphere of lettuce under field conditions analyzed by whole metagenome sequencing

doi: 10.3389/fmicb.2014.00252 Effect of the strain Bacillus amyloliquefaciens FZB42 on the microbial community in the rhizosphere of lettuce under field conditions analyzed by whole metagenome sequencin