WDX-Analysis of the New Superconductors RO1−x F x FeAs and Its Consequences on the Electronic Phase Diagram

Polycrystalline samples of RO_1−x F _x FeAs (0≤x≤0.25) (R=La, Sm, Gd) were investigated by wavelength-dispersive X-ray spectroscopy (WDX) in the electron microscope to determine the composition of the samples, in particular the fluorine content. It was found that the measured fluorine content can deviate considerably from the initial weight. In the lanthanum compound LaO_1−x F _x FeAs, we found good agreement mainly for x≥0.05, but for x<0.05 the fluorine hardly goes into the sample. For the samarium compound we measured less than half the fluorine in the sample as initially weighed at all fluorine concentrations. These measured values are taken into account when drawing the electronic phase diagrams of LaO_1−x F _x FeAs and SmO_1−x F _x FeAs. This leads to a more consistent picture of both of the diagrams in comparison to the plot of the initial weight.     

A 1-year prospective study of panic attacks: Clinical course and factors associated with maintenance.

A prospective naturalistic l-year follow-up study of 39 patients with current panic disorder, 17 remitted panic patients, 46 infrequent panickers, 22 patients with simple phobias, and 45 controls assessed clinical course and variables related to the maintenance of panic attacks. Nearly all panic disorder patients (92%) continued to experience panic attacks, and 41% of the initially remitted patients relapsed. No significant effects of treatments delivered in the community were found. Infrequent panickers tended to be more likely to develop panic disorder (15%) than controls (2%). Maintenance/relapse was most consistently linked with good heartbeat perception, anxiety sensitivity, and avoidance in the different subsamples. Patients with simple phobias or normal controls who experienced their first panic attack during follow-up had shown higher anxiety sensitivity at initial assessment than nonpanickers. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Overgeneral memory extends to pictorial retrieval cues and correlates with cognitive features in posttraumatic stress disorder.

Individuals with posttraumatic stress disorder (PTSD) show overgeneral memory (OGM) when retrieving autobiographical memories to word cues. We investigated whether OGM extends to picture cues and whether it is related to PTSD symptoms and cognitions. Trauma survivors with (n = 29) and without (n = 26) PTSD completed the standard Autobiographical Memory Test (AMT) and a novel picture version. Compared to the no-PTSD group, the PTSD group showed OGM in both test versions. Pictures facilitated specific memory retrieval, but this effect was no longer significant when verbal intelligence or depressive symptoms were controlled. OGM correlated with PTSD symptoms and perceived self-change; with intrusive memories, their perceived "nowness," responses to intrusions (thought suppression, rumination, dissociation), and negative interpretations of symptoms. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Amino‐polyvinyl Alcohol Coated Superparamagnetic Iron Oxide Nanoparticles are Suitable for Monitoring of Human Mesenchymal Stromal Cells In Vivo

Mesenchymal stromal cells (MSCs) are promising candidates in regenerative cell‐therapies. However, optimizing their number and route of delivery remains a critical issue, which can be addressed by monitoring the MSCs’ bio‐distribution in vivo using super‐paramagnetic iron‐oxide nanoparticles (SPIONs). In this study, amino‐polyvinyl alcohol coated (A‐PVA) SPIONs are introduced for cell‐labeling and visualization by magnetic resonance imaging (MRI) of human MSCs. Size and surface charge of A‐PVA‐SPIONs differ depending on their solvent. Under MSC‐labeling conditions, A‐PVA‐SPIONs have a hydrodynamic diameter of 42 ± 2 nm and a negative Zeta potential of 25 ± 5 mV, which enable efficient internalization by MSCs without the need to use transfection agents. Transmission X‐ray microscopy localizes A‐PVA‐SPIONs in intracellular vesicles and as cytosolic single particles. After identifying non‐interfering cell‐assays and determining the delivered and cellular dose, in addition to the administered dose, A‐PVA‐SPIONs are found to be non‐toxic to MSCs and non‐destructive towards their multi‐lineage differentiation potential. Surprisingly, MSC migration is increased. In MRI, A‐PVA‐SPION‐labeled MSCs are successfully visualized in vitro and in vivo. In conclusion, A‐PVA‐SPIONs have no unfavorable influences on MSCs, although it becomes evident how sensitive their functional behavior is towards SPION‐labeling. And A‐PVA‐SPIONs allow MSC‐monitoring in vivo.     

Effects of Zwitterionic buffers on sorption of ferrous iron at goethite and its oxidation by CCl4

A major factor which controls sorption and oxidation of Fe(II) at the mineral-water interface is pH, hence buffers are commonly used to control pH in experimental studies. Here, we examined the effects of widely used organic buffers (3-morpholinopropane-1-sulfonic acid (MOPS) and 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES)) on Fe(II) uptake and oxidation by CCl(4) in aqueous suspensions of goethite. Significant sorption of these zwitterionic buffers occurred only at Fe(II)-loaded goethite but not at native goethite. The addition of MOPS and HEPES caused substantial release of Fe(II) from goethite, retarded the oxidation of surface-bound Fe(II) by CCl(4) and changed the reaction pathway as indicated by lower yields of CHCl(3). To explore electrostatic and steric contributions of MOPS and HEPES to the observed phenomena we studied sorption and competitive effects of model sorbates (Ca(2+), sulfonates) which suggest the formation of a complex between surface-bound Fe(II) and MOPS or HEPES. Our study shows for the first time that these frequently used zwitterionic organic buffers may interfere significantly with the surface chemistry and thus with redox reactions of Fe(II) at goethite. Hence, kinetic or mechanistic information obtained in such systems requires careful interpretation.     

Pathological anatomy of alimentary fluorine deficiency in goats

Chronic alimentary fluorine deficiency was provoked in goats by a semisynthetic diet with fruorine deficiency (less than 0.3 mg/kg dry feed). Teeth caries, emaciation in spite of higher consumption of food as compared to controls, focal inflammatory degenerative changes in the alimentary tract mucous membranes (catarrhal-purulent esophagitis, chronic duodenitis), chronic degenerative changes in the parenchymatous organs were observed. Endocrinopathies, accidental thymus involution, hypothyroid state, destructive changes in the pancreatic insullar cells were also common.     

The oxidation of benzene under conditions encountered in waste incinerators

The oxidation of benzene was studied as a function of residence time (τ_res=0–2.5 s), temperature (850–960 K), and oxygen concentration (O₂=0.2–2.3%) in a heated laminar flow reactor at atmospheric pressure. Nitrogen, doped with 350 ppm benzene, was injected downstream of the burned gas from a near stoichiometric flame of methane + air. Gas samples were taken at different heights up the reactor and analyzed using GC-FID/TCD and HPLC techniques. Phenol and partially oxidized hydrocarbons such as acetaldehyde, formaldehyde, and acrolein were found with concentrations up to 50 ppm. At relatively low temperatures, the conversion of benzene was observed to proceed considerably more slowly at higher oxygen concentrations. Measured concentration profiles were modeled using detailed reaction schemes. A modified mechanism for the oxidation of benzene called BenWas was constructed from the mechanism of Zhang and McKinnon (Combust. Sci. Technol. 107 (1995) 261) by incorporating a submechanism for benzoquinone (OC₆H₄O) and by updating and enlarging the reaction scheme of cyclopentadiene (C₅H₆). The agreement between observed and predicted concentration profiles, e.g., of phenol (C₆H₅OH), acetylene (C₂H₂), and carbon monoxide (CO), was considerably improved by the use of the BenWas mechanism for rich and lean conditions, mainly due to the introduction of an additional pathway for phenyl oxidation (C₆H₅ + O₂ = OC₆H₄O + H) and due to the changed kinetics of the oxidation of cyclopentadienyl (C₅H₅) in C₅H₅ + O₂ = C₅H₄O + OH. The measured retardation of benzene oxidation with higher amounts of oxygen can be explained by the formation and reactions of peroxy radicals.     

Hydrodynamische Einlauflänge und Widerstandsgesetz von reibungsmindernden kationschen Tensidlösungen

Zusammenfassung Durch Zugabe geeigneter Tensidsysteme in Wasser kann der Str?mungsdruckverlust in geraden Rohren erheblich gesenkt werden. Die diesem Effekt zugrunde liegenden Mechanismen wurden in früheren Arbeiten eingehend diskutiert. In dieser Arbeit werden neue Ergebnisse vorgestellt, die sowohl die Bestimmung der hydrodynamischen Einlaufl?nge als auch die Ermittlung der Widerstandsbeiwerte im ausgebildeten Str?mungszustand erm?glichen. Für den Bereich der ausgebildeten Rohrstr?mung wird eine neue Berechnungsgleichung vorgeschlagen. Durch Erweiterung der bisherigen Modellvorstellungen ergibt sich ein Widerstandsgesetz für den gesamten Wirkungsbereich des Tensids. Die Ergebnisse stützen sich auf Untersuchungen mit zwei verschiedenen Additivsystemen, bei denen die Parameter Str?mungsgeschwindigkeit, Temperatur und Einsatzkonzentration variiert wurden.