Hexagonal Si-Ge Class of Semiconducting Alloys Prepared Using Pressure and Temperature

Multi-anvil and laser-heated diamond anvil methods have been used to subject Ge and Si mixtures to pressures and temperatures of between 12 and 17 GPa and 1500–1800 K, respectively. Synchrotron angle dispersive X-ray diffraction, precession electron diffraction and chemical analysis using electron microscopy, reveal recovery atambient pressure of hexagonal Ge-Si solid solutions (P6$_3$/mmc). Taken together, the multi-anvil and diamond anvil results reveal that hexagonal solid solutions can be preparedfor all Ge-Si compositions. This hexagonal class of solid solutions constitutes a significant expansion of the bulk Ge-Sisolid solution family, and is of interest for optoelectronic applications

Electrochemically generated peryleniumyl-hexafluorophosphate and hexafluoroarsenate : new one-dimensional metals

Compounds of stoichiometry (pe)2(PF6)1.1x times 0.8CH2Cl2(1) (pe = perylene), (pe)2(AsF6)1.1 timesx 0.7 CH2Cl2 (2), (pe)2(PF6)1.4 times 0.6 THF (3), (pe)2(AsF6)1.5x times 0.5 THF (4) and (pe)3(SbF6)2 times 0.75 CH2Cl2 (5) have been obtained as crystalline samples by electrochemical deposition from CH2Cl2 [(1), (2) and (5)] or from THF [(3) and (4)] solutions of perylene, containing the appropriate counterion. The three compounds (1)-(3) crystallize in isomorphous orthorhombic lattices. (1) forms black needles: space group Pnmn with a = 4.285 Aring, b = 12.915 Aring and c = 14.033 Aring, z = 1. (2) gives black needles, orthorhombic space group Pnmn with a = 4.294 Aring, b = 13.077 Aring, and c = 14.132 Aring, z = 1. The structures of (1) and (2) were solved by direct methods and refined by least squares to final R = 0.148 and R = 0.088 based on 476 and 322 observed reflections. The perylene forms segregated stacks in direction of the a-axis with interplanar distances of 3.40 Aring and an angle of 37.7° between the bc-plane and the perylene. The channels between the segregated stacks are filled by anions and solvent molecules. The d.c. conductivities (four probe measurements) of (1)-(4) fall in the range of 70-1200Ω-1. cm-1 at room temperature. The conductivities show a metallic regime down to about 200°K and drop off below that temperature

Highly conducting perylene radical salts

Temperature dependent dc and microwave conductivity data together with EPR and optical reflectance measurements on the "mixed" system (pe)2(ASF6)0,75(PF6)0,35 times 0,85 CH2Cl2 are described. The data prove metallic behaviour of this organic solid down to 200 K

An asteroseismic membership study of the red giants in three open clusters observed by Kepler: NGC6791, NGC6819, and NGC6811

Studying star clusters offers significant advances in stellar astrophysics due to the combined power of having many stars with essentially the same distance, age, and initial composition. This makes clusters excellent test benches for verification of stellar evolution theory. To fully exploit this potential, it is vital that the star sample is uncontaminated by stars that are not members of the cluster. Techniques for determining cluster membership therefore play a key role in the investigation of clusters. We present results on three clusters in the Kepler field of view based on a newly established technique that uses asteroseismology to identify fore- or background stars in the field, which demonstrates advantages over classical methods such as kinematic and photometry measurements. Four previously identified seismic non-members in NGC6819 are confirmed in this study, and three additional non-members are found -- two in NGC6819 and one in NGC6791. We further highlight which stars are, or might be, affected by blending, which needs to be taken into account when analysing these Kepler data.Comment: 12 pages, 9 figures, 5 tables, accepted by Ap

Risk Balancing of Cold Ischemic Time against Night Shift Surgery Possibly Reduces Rates of Reoperation and Perioperative Graft Loss

Background. This retrospective cohort study evaluates the advantages of risk balancing between prolonged cold ischemic time (CIT) and late night surgery. Methods. 1262 deceased donor kidney transplantations were analyzed. Multivariable regression was used to determine odds ratios (ORs) for reoperation, graft loss, delayed graft function (DGF), and discharge on dialysis. CIT was categorized according to a forward stepwise pattern ≤1h/>1h, ≤2h/>2h, ≤3h/>3h, . . ., ≤nh/>nh. ORs for DGF were plotted against CIT and a nonlinear regression function with best 2 was identified. First and second derivative were then implemented into the curvature formula ( ) = ( )/(1 + ( ) 2 ) 3/2 to determine the point of highest CIT-mediated risk acceleration. Results. Surgery between 3 AM and 6 AM is an independent risk factor for reoperation and graft loss, whereas prolonged CIT is only relevant for DGF. CIT-mediated risk for DGF follows an exponential pattern ( ) = ⋅ (1 + ⋅ ( ⋅ ) ) with a cut-off for the highest risk increment at 23.5 hours. Conclusions. The risk of surgery at 3 AM-6 AM outweighs prolonged CIT when confined within 23.5 hours as determined by a new mathematical approach to calculate turning points of nonlinear time related risks. CIT is only relevant for the endpoint of DGF but had no impact on discharge on dialysis, reoperation, or graft loss

Asteroseismology of the open clusters NGC 6791, NGC 6811, and NGC 6819 from nineteen months of Kepler photometry

We studied solar-like oscillations in 115 red giants in the three open clusters NGC 6791, NGC 6811, and NGC 6819, based on photometric data covering more than 19 months with NASA's Kepler space telescope. We present the asteroseismic diagrams of the asymptotic parameters \delta\nu_02, \delta\nu_01 and \epsilon, which show clear correlation with fundamental stellar parameters such as mass and radius. When the stellar populations from the clusters are compared, we see evidence for a difference in mass of the red giant branch stars, and possibly a difference in structure of the red clump stars, from our measurements of the small separations \delta\nu_02 and \delta\nu_01. Ensemble \'{e}chelle diagrams and upper limits to the linewidths of l = 0 modes as a function of \Delta\nu of the clusters NGC 6791 and NGC 6819 are also shown, together with the correlation between the l = 0 ridge width and the T_eff of the stars. Lastly, we distinguish between red giant branch and red clump stars through the measurement of the period spacing of mixed dipole modes in 53 stars among all the three clusters to verify the stellar classification from the color-magnitude diagram. These seismic results also allow us to identify a number of special cases, including evolved blue stragglers and binaries, as well as stars in late He-core burning phases, which can be potentially interesting targets for detailed theoretical modeling.Comment: 30 pages, 15 figures, 1 table, accepted to Ap

Electrochemical synthesis of new one-dimensional metals: radical salts of perylene

The electrochemical synthesis of four highly conducting peryleniumyl salts is reported. The temperature dependence of the conductivity has been measured and exhibits a metallic regime between 200-300 K. The crystal structures of two of the compounds have been solved

Primary gastric non-Hodgkin's lymphoma in Chinese patients: clinical characteristics and prognostic factors

<p>Abstract</p> <p>Background</p> <p>Optimal management and outcome of primary gastric lymphoma (PGL) have not been well defined in the rituximab era. This study aimed to analyze the clinical characteristics, prognostic factors, and roles of different treatment modalities in Chinese patients with PGL.</p> <p>Methods</p> <p>The clinicopathological features of 83 Chinese patients with PGL were retrospectively reviewed. Staging was performed according to the Lugano staging system for gastrointestinal non-Hodgkin's lymphoma.</p> <p>Results</p> <p>The predominant pathologic subtype among Chinese patients with PGL in our study was diffuse large B cell lymphoma (DLBCL), followed by mucosa-associated lymphoid tissue (MALT) lymphoma. Among the 57 patients with gastric DLBCL, 20 patients (35.1%) were classified as the germinal center B cell-like (GCB) subtype and 37 patients (64.9%) as the non-GCB subtype. The 83 patients had a five-year overall survival (OS) and event-free survival (EFS) of 52% and 59%, respectively. Cox regression analysis showed that stage-modified international prognostic index (IPI) and performance status (PS) were independent predictors of survival. In the 67 B-cell lymphoma patients who received chemotherapy, 36 patients treated with rituximab (at least 3 cycles) had a mean OS of 72 months (95% CI 62-81) versus 62 months (95% CI 47-76) for patients without rituximab treatment (P = 0.021).</p> <p>Conclusion</p> <p>The proportion of Chinese gastric DLBCL cases with non-GCB subtype was higher than the GCB subtype. Stage-modified IPI and PS were effective prognostic factors in Chinese patients with PGL. Our data suggested that primary gastric B-cell lymphoma might have an improved outcome with rituximab in addition to chemotherapy. More studies are necessary, preferentially large prospective randomized clinical trials to obtain more information on the impact of the rituximab in the primary gastric B-cell lymphoma.</p