Carbon radio recombination lines from gigahertz to megahertz frequencies towards Orion A

Context. The combined use of carbon radio recombination lines (CRRLs) and the 158 $\mu$m-[CII] line is a powerful tool for the study of the energetics and physical conditions (e.g., temperature and density) of photodissociation regions (PDRs). However, there are few observational studies that exploit this synergy. Aims. Here we explore the relation between CRRLs and the 158 $\mu$m-[CII] line in light of new observations and models. Methods. We present new and existing observations of CRRLs in the frequency range 0.15--230 GHz with ALMA, VLA, the GBT, Effelsberg 100m, and LOFAR towards Orion~A (M42). We complement these observations with SOFIA observations of the 158 $\mu$m-[CII] line. We studied two PDRs: the foreground atomic gas, known as the Veil, and the dense PDR between the HII region and the background molecular cloud. Results. In the Veil we are able to determine the gas temperature and electron density, which we use to measure the ionization parameter and the photoelectric heating efficiency. In the dense PDR, we are able to identify a layered PDR structure at the surface of the molecular cloud to the south of the Trapezium cluster. There we find that the radio lines trace the colder portion of the ionized carbon layer, the C$^{+}$/C/CO interface. By modeling the emission of the $158$~$\mu$m-[CII] line and CRRLs as arising from a PDR we derive a thermal pressure $>5\times10^{7}$ K cm$^{-3}$ and a radiation field $G_{0}\approx10^{5}$ close to the Trapezium. Conclusions. This work provides additional observational support for the use of CRRLs and the 158 $\mu$m-[CII] line as complementary tools to study dense and diffuse PDRs, and highlights the usefulness of CRRLs as probes of the C$^{+}$/C/CO interface.Comment: 18 pages, 16 figures, accepted for publication in A&

Discontinuous unbinding of lipid multibilayers

We have observed a discontinuous unbinding transition of lipid bilayer stacks composed of phosphatidylethanolamine and phosphatidylglycerol using X-ray diffraction. The unbinding is reversible and coincides with the main (Lβ→Lα) transition of the lipid mixture. Interbilayer interaction potentials deduced from the diffraction data reveal that the bilayers in the Lβ phase are only weakly bound. The unbinding transition appears to be driven by an abrupt increase in steric repulsion resulting from increased thermal undulations of the bilayers upon entering the fluid Lαphase

Heterogeneity within AML with CEBPA mutations; only CEBPA double mutations, but not single CEBPA mutations are associated with favourable prognosis

CCAAT/enhancer binding protein alpha (CEBPA) mutations in AML are associated with favourable prognosis and are divided into N- and C-terminal mutations. The majority of AML patients have both types of mutations. We assessed the prognostic significance of single (n=7) and double (n=12) CEBPA mutations among 224 AML patients. Double CEBPA mutations conferred a decisively favourable overall (P=0.006) and disease-free survival (P=0.013). However, clinical outcome of patients with single CEBPA mutations was not different from CEBPA wild-type patients. In a multivariable analysis, only double – but not single – CEBPA mutations were identified as independent prognostic factors. These findings indicate heterogeneity within AML patients with CEBPA mutations

The Conduit System Transports Soluble Antigens from the Afferent Lymph to Resident Dendritic Cells in the T Cell Area of the Lymph Node

AbstractResident dendritic cells (DC) within the T cell area of the lymph node take up soluble antigens that enter via the afferent lymphatics before antigen carrying DC arrive from the periphery. The reticular network within the lymph node is a conduit system forming the infrastructure for the fast delivery of soluble substances from the afferent lymph to the lumen of high endothelial venules (HEVs). Using high-resolution light microscopy and 3D reconstruction, we show here that these conduits are unique basement membrane-like structures ensheathed by fibroblastic reticular cells with occasional resident DC embedded within this cell layer. Conduit-associated DC are capable of taking up and processing soluble antigens transported within the conduits, whereas immigrated mature DC occur remote from the reticular fibers. The conduit system is, therefore, not a closed compartment that shuttles substances through the lymph node but represents the morphological equivalent to the filtering function of the lymph node

Complexation of lanthanides, actinides and transition metal cations with a 6-(1,2,4-triazin-3-yl)-2,2’:6’,2’’-terpyridine ligand: implications for actinide(III) /lanthanide(III) partitioning

The quadridentate N-heterocyclic ligand 6-(5,5,8,8-tetramethyl-5,6,7,8-tetrahydro-1,2,4-benzotriazin-3-yl)-2,2’:6’,2’’-terpyridine (CyMe4-hemi-BTBP) has been synthesized and its interactions with Am(III), U(VI), Ln(III) and some transition metal cations have been evaluated by X-ray crystallographic analysis, Am(III)/Eu(III) solvent extraction experiments, UV absorption spectrophotometry, NMR studies and ESI-MS. Structures of the 1:1 complexes with Eu(III), Ce(III) and the linear uranyl (UO22+) ion were obtained by X-ray crystallographic analysis, and showed similar coordination behavior to related BTBP complexes. In methanol, the stability constants of the Ln(III) complexes are slightly lower than those of the analogous quadridentate bis-triazine BTBP ligands, while the stability constant for the Yb(III) complex is higher. 1H NMR titrations and ESI-MS with lanthanide nitrates showed that the ligand forms only 1:1 complexes with Eu(III), Ce(III) and Yb(III), while both 1:1 and 1:2 complexes were formed with La(III) and Y(III) in acetonitrile. A mixture of isomeric chiral 2:2 helical complexes was formed with Cu(I), with a slight preference (1.4:1) for a single directional isomer. In contrast, a 1:1 complex was observed with the larger Ag(I) ion. The ligand was unable to extract Am(III) or Eu(III) from nitric acid solutions into 1-octanol, except in the presence of a synergist at low acidity. The results show that the presence of two outer 1,2,4-triazine rings is required for the efficient extraction and separation of An(III) from Ln(III) by quadridentate N-donor ligand

A swollen phase observed between the liquid-crystalline phase and the interdigitated phase induced by pressure and/or adding ethanol in DPPC aqueous solution

A swollen phase, in which the mean repeat distance of lipid bilayers is larger than the other phases, is found between the liquid-crystalline phase and the interdigitated gel phase in DPPC aqueous solution. Temperature, pressure and ethanol concentration dependences of the structure were investigated by small-angle neutron scattering, and a bending rigidity of lipid bilayers was by neutron spin echo. The nature of the swollen phase is similar to the anomalous swelling reported previously. However, the temperature dependence of the mean repeat distance and the bending rigidity of lipid bilayers are different. This phase could be a precursor to the interdigitated gel phase induced by pressure and/or adding ethanol.Comment: 7 pages, 6 figure