Predicted suppression of the superconducting transition of new high-pressure yttrium phases with increasing pressure from first-principles calculations

Structure searches for new high-pressure phases of Y metal have been performed by using evolutionary algorithms in conjunction with a first-principles, pseudopotential plane-wave method based on density functional theory. The oF16-Fddd and hP3-P3 121 phases are predicted to be energetically favorable at pressures over 97 GPa. These two phases are shown to be dynamically stable by computing their phonon dispersions. We thus propose that oF16-Fddd and hP3-P3 121 are the most probable crystal structures Y may take in the 97-206 GPa range. The superconducting critical temperatures (T c) of the new phases are estimated using the Allen-Dynes formula. The T c is predicted to decrease with increasing pressure over about 100 GPa, in sharp contrast to its observed monotonic increase under lower pressure. The electronic origins of the stabilities of the proposed high-pressure phases have also been investigated.published_or_final_versio

Electronic Raman Scattering On Individual Semiconducting Single Walled Carbon Nanotubes

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Ameliorative Effects of Neurolytic Celiac Plexus Block on Stress and Inflammation in Rats with Partial Hepatectomy

Purpose: To investigate effects of neurolytic celiac plexus block (NCPB) on stress and inflammation in rats with partial hepatectomy (PH).Methods: A model of PH rat was established, and serum C-reactive protein (CRP); corticosterone (GC); adrenocorticotropin (ACTH); noradrenaline (NA); adrenalin (AD); aspartate transaminase (AST); alanine transaminase (ALT); as well as tumor necrosis factor-α (TNF-α); interleukin (IL)-1β and IL-6; high mobility group box1 (HMGB1); and nitric oxide (NO) concentrations in serum assessed after PH. Additionally, Western blotting was performed to determine the effect of NCPB on expressions of glucocorticoid receptors (GR), inhibitor of nuclear factor kappa B (IκB), p65, c-Jun and inducible nitric oxide synthase (iNOS) of PH rats, as well as assay effects of NCPB on nuclear translocation of GR, c- Jun and p65. DNA binding activities of nuclear factor kappa B (NF-κB) and activator protein 1 (AP-1) were also determined.Results: NCPB reduced AST and ALT (P < 0.05), decreased secretion of inflammatory cytokines and NO (P < 0.05), as well as decreased CRP, GC, ACTH, NA and AD after PH (p < 0.05). NCPB increased expressions of GR and IκB, but expressions of p65, c-Jun, and iNOS (p < 0.05). Additionally, NCPB increased nuclear translocation of GR (p < 0.01), but decreased nuclear translocation of p65 and c-Jun after PH (p < 0.05). Additionally, DNA binding activity of NF-κB and AP-1 was decreased by NCPB (p < 0.05).Conclusion: The results indicate that NCPB treatment can significantly inhibit stress and inflammation in PH rats.Keywords: Neurolytic celiac plexus block, Cytokine, Nuclear translocation, Partial hepatectomy, Stress, Inflammatio

Repeatability of Corneal Elevation Maps in Keratoconus Patients Using the Tomography Matching Method

To assess repeatability of corneal tomography in successive measurements by Pentacam in keratoconus (KC) and normal eyes based on the Iterative Closest Point (ICP) algorithm. The study involved 143 keratoconic and 143 matched normal eyes. ICP algorithm was used to estimate six single and combined misalignment (CM) parameters, the root mean square (RMS) of the difference in elevation data pre (PreICP-RMS) and post (PosICP-RMS) tomography matching. Corneal keratometry, expressed in the form of M, J0 and J45 (power vector analysis parameters), was used to evaluate the effect of misalignment on corneal curvature measurements. The PreICP-RMS and PosICP-RMS were statistically higher (P < 0.01) in KC than normal eyes. CM increased significantly (p = 0.00), more in KC (16.76 ± 20.88 μm) than in normal eyes (5.43 ± 4.08 μm). PreICP-RMS, PosICP-RMS and CM were correlated with keratoconus grade (p < 0.05). Corneal astigmatism J0 was different (p = 0.01) for the second tomography measurements with misalignment consideration (−1.11 ± 2.35 D) or not (−1.18 ± 2.35 D), while M and J45 kept similar. KC corneas consistently show higher misalignments between successive tomography measurements and lower repeatability compared with healthy eyes. The influence of misalignment is evidently clearer in the estimation of astigmatism than spherical curvature. These higher errors appear correlated with KC progression

Host-specific genetic variation of highly pathogenic avian influenza viruses (H5N1)

The complete genome sequences of two isolates A/chicken/Egypt/CL6/07 (CL6/07) and A/duck/Egypt/D2br10/07 (D2br10/07) of highly pathogenic avian influenza virus (HPAI) H5N1 isolated at the beginning of 2007 outbreak in Egypt were determined and compared with all Egyptian HPAI H5N1 sequences available in the GenBank. Sequence analysis utilizing the RNA from the original tissue homogenate showed amino acid substitutions in seven of the viral segments in both samples. Interestingly, these changes were different between the CL6/07 and D2br10/07 when compared to other Egyptian isolates. Moreover, phylogenetic analysis showed independent sub-clustering of the two viruses within the Egyptian sequences signifying a possible differential adaptation in the two hosts. Further, pre-amplification analysis of H5N1 might be necessary for accurate data interpretation and identification of distinct factor(s) influencing the evolution of the virus in different poultry species

Reemerging superconductivity at 48 K across quantum criticality in iron chalcogenides

Pressure plays an essential role in the induction1 and control2,3 of superconductivity in iron-based superconductors. Substitution of a smaller rare-earth ion for the bigger one to simulate the pressure effects has surprisingly raised the superconducting transition temperature Tc to the record high 55 K in these materials4,5. However, Tc always goes down after passing through a maximum at some pressure and the superconductivity eventually tends to disappear at sufficiently high pressures1-3. Here we show that the superconductivity can reemerge with a much higher Tc after its destruction upon compression from the ambient-condition value of around 31 K in newly discovered iron chalcogenide superconductors. We find that in the second superconducting phase the maximum Tc is as high as 48.7 K for K0.8Fe1.70Se2 and 48 K for (Tl0.6Rb0.4)Fe1.67Se2, setting the new Tc record in chalcogenide superconductors. The presence of the second superconducting phase is proposed to be related to pressure-induced quantum criticality. Our findings point to the potential route to the further achievement of high-Tc superconductivity in iron-based and other superconductors.Comment: 20 pages and 7 figure