WDX-Analysis of the New Superconductors RO(1-x)F(x)FeAs and Its Consequences on the Electronic Phase Diagram

Polycrystalline samples of RO1-xFxFeAs (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 LaO1-xFxFeAs, 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 LaO1-xFxFeAs and SmO1-xFxFeAs. This leads to a more consistent picture of both of the diagrams in comparison to the plot of the initial weight.Comment: 5 pages, 4 figures, Accepted for publication in Journal of Superconductivity and Novel Magnetis

g factor of lithiumlike silicon 28Si11+

The g factor of lithiumlike 28Si11+ has been measured in a triple-Penning trap with a relative uncertainty of 1.1x10^{-9} to be g_exp=2.0008898899(21). The theoretical prediction for this value was calculated to be g_th=2.000889909(51) improving the accuracy to 2.5x10^{-8} due to the first rigorous evaluation of the two-photon exchange correction. The measured value is in excellent agreement with the state-of-the-art theoretical prediction and yields the most stringent test of bound-state QED for the g factor of the 1s^22s state and the relativistic many-electron calculations in a magnetic field

Manufacturing conditioned wear of all-ceramic knee prostheses

To date, bioceramics have not been applied successfully in total knee joint endoprostheses. Sintered bioceramics can be machined only by grinding and polishing processes. Due to high quality requirements, there are significant challenges with regard to these machining technologies. An automated precise economical process chain for the manufacturing of a new all-ceramic knee implant design was developed. It was assumed the geometrical accuracy and the shape of implant contact geometry specified during the manufacturing process has a substantial influence on the wear behavior of the prosthesis. The importance of the surface quality of the ceramic implant surface remains unclear and warrants future examination

High-precision measurement of the atomic mass of the electron

The quest for the value of the electron's atomic mass has been subject of continuing efforts over the last decades. Among the seemingly fundamental constants which parameterize the Standard Model (SM) of physics and which are thus responsible for its predictive power, the electron mass me plays a prominent role, as it is responsible for the structure and properties of atoms and molecules. This manifests in the close link with other fundamental constants, such as the Rydberg constant and the fine-structure constant {\alpha}. However, the low mass of the electron considerably complicates its precise determination. In this work we present a substantial improvement by combining a very accurate measurement of the magnetic moment of a single electron bound to a carbon nucleus with a state-of-the-art calculation in the framework of bound-state Quantum Electrodynamics. The achieved precision of the atomic mass of the electron surpasses the current CODATA value by a factor of 13. Accordingly, the result presented in this letter lays the foundation for future fundamental physics experiments and precision tests of the SM

Influence of stress on the degradation behavior of Mg LAE442 implant systems

In this paper the performance of a magnesium based implant system is analyzed. A special emphasis is placed on the impact of stress on the corrosion behavior of the magnesium alloy. An implant system containing a plate and 4 corresponding screws is machined from Mg LAE442. Its corrosion behavior is tested in-vivo in New Zealand White Rabbits for 6 and 12 weeks of implantation. The plate is monocortically fixated on the medial tibia. At the interface between screw and plate increased corrosion is observed. This phenomenon is stronger on the caudal side of the screw. Parallel to the in-vivo test the influence of stress load on the corrosion rate is analyzed for LAE442 in in-vitro tests. Compressive load is applied on cylindrical specimens in axial direction and the corrosion rate is measured in 0.9 wt% NaCl solution by eudiometry and mass loss. Additionally rectangular samples are bent to apply tensile stress on the surface. A drop of 5 wt% NaCl is deposited on the surface and the corrosion is evaluated by microscopic images. It is shown that stress essentially influences the corrosion rate. While tensile stress decreases the corrosion, compressive stress leads to higher corrosion rates

Manufacturing conditioned roughness and wear of biomedical oxide ceramics for all-ceramic knee implants

Background: Ceramic materials are used in a growing proportion of hip joint prostheses due to their wear resistance and biocompatibility properties. However, ceramics have not been applied successfully in total knee joint endoprostheses to date. One reason for this is that with strict surface quality requirements, there are significant challenges with regard to machining. High-toughness bioceramics can only be machined by grinding and polishing processes. The aim of this study was to develop an automated process chain for the manufacturing of an all-ceramic knee implant. Methods: A five-axis machining process was developed for all-ceramic implant components. These components were used in an investigation of the influence of surface conformity on wear behavior under simplified knee joint motion. Results: The implant components showed considerably reduced wear compared to conventional material combinations. Contact area resulting from a variety of component surface shapes, with a variety of levels of surface conformity, greatly influenced wear rate. Conclusions: It is possible to realize an all-ceramic knee endoprosthesis device, with a precise and affordable manufacturing process. The shape accuracy of the component surfaces, as specified by the design and achieved during the manufacturing process, has a substantial influence on the wear behavior of the prosthesis. This result, if corroborated by results with a greater sample size, is likely to influence the design parameters of such devices.DFG/CRC/59

Synthesis and physical properties of LaO1−xFxFeAs\rm\bf LaO_{1-x}F_xFeAs

We have prepared the newly discovered Fe-based superconducting material $\rm LaO_{1-x}F_xFeAs$ ($0\leq x\leq 0.2$) in polycrystalline form and have investigated the samples by means of structural, thermodynamic and transport measurements. Our investigations reveal a non superconducting phase at $0\leq x\lesssim0.04$ which for $x=0$ is characterized by a structural transition towards an orthorhombic distortion at $T_s\approx 160$ K and antiferromagnetic spin order at $T_N\approx138$ K. Both transitions lead to strong anomalies in various transport properties as well as in magnetization and in specific heat. Remarkably, the transition temperatures are only weakly doping dependent up $x\lesssim 0.04$. However, the transitions are abruptly suppressed at $x\geq0.05$ in favour of a superconducting phase with a critical temperature $T_c\gtrsim 20$ K. Upon further increasing the F-doping $T_c$ increases up to a maximum of $T_c=26.8$ K at $x=0.1$ which is followed by a decrease down to $T_c\approx10$ K at $x\geq0.15$

Genetic Variation in ABCC4 and CFTR and Acute Pancreatitis during Treatment of Pediatric Acute Lymphoblastic Leukemia

Background: Acute pancreatitis (AP) is a serious, mechanistically not entirely resolved side effect of L-asparaginase-containing treatment for acute lymphoblastic leukemia (ALL). To find new candidate variations for AP, we conducted a genome-wide association study (GWAS). Methods: In all, 1,004,623 single-nucleotide variants (SNVs) were analyzed in 51 pediatric ALL patients with AP (cases) and 1388 patients without AP (controls). Replication used independent patients. Results: The top-ranked SNV (rs4148513) was located within the ABCC4 gene (odds ratio (OR) 84.1; p = 1.04 × 10−14). Independent replication of our 20 top SNVs was not supportive of initial results, partly because rare variants were neither present in cases nor present in controls. However, results of combined analysis (GWAS and replication cohorts) remained significant (e.g., rs4148513; OR = 47.2; p = 7.31 × 10−9). Subsequently, we sequenced the entire ABCC4 gene and its close relative, the cystic fibrosis associated CFTR gene, a strong AP candidate gene, in 48 cases and 47 controls. Six AP-associated variants in ABCC4 and one variant in CFTR were detected. Replication confirmed the six ABCC4 variants but not the CFTR variant. Conclusions: Genetic variation within the ABCC4 gene was associated with AP during the treatment of ALL. No association of AP with CFTR was observed. Larger international studies are necessary to more conclusively assess the risk of rare clinical phenotypes

CO2 Image: The design of an imaging spectrometer for CO2 point source quantification

CO2Image is a satellite demonstration mission, now in Phase B, to be launched in 2026 by the German Aerospace Center (DLR). The satellite will carry a next generation imaging spectrometer for measuring atmospheric column concentrations of Carbon Dioxide (CO2). The instrument concept reconciles compact design with fine ground resolution (50-100 m) with decent spectral resolution (1.0-1.3 nm) in the shortwave infrared spectral range (2000 nm). Thus, CO2Image will enable quantification of point source CO2 emission rates of less than 1 MtCO2/a. This will complement global monitoring missions such as CO2M, which are less sensitive to point sources due to their coarser ground resolution and hyperspectral imagers, which suffer from spectroscopic interference errors that limit the quantification