Direct limit of matrix ordered spaces

In this paper we initiate the study of ordered f-bimodules as the inductive limit of matrix ordered spaces

Synthesis of possible room temperature superconductor LK-99:Pb9_9Cu(PO4_4)6_6O

The quest for room-temperature superconductors has been teasing scientists and physicists, since its inception in 1911 itself. Several assertions have already been made about room temperature superconductivity but were never verified or reproduced across the labs. The cuprates were the earliest high transition temperature superconductors, and it seems that copper has done the magic once again. Last week, a Korean group synthesized a Lead Apatite-based compound LK-99, showing a T$_c$ of above 400$^\circ$K. The signatures of superconductivity in the compound are very promising, in terms of resistivity (R = 0) and diamagnetism at T$_c$. Although, the heat capacity (C$_p$) did not show the obvious transition at T$_c$. Inspired by the interesting claims of above room temperature superconductivity in LK-99, in this article, we report the synthesis of polycrystalline samples of LK-99, by following the same heat treatment as reported in [1,2] by the two-step precursor method. The phase is confirmed through X-ray diffraction (XRD) measurements, performed after each heat treatment. The room temperature diamagnetism is not evidenced by the levitation of a permanent magnet over the sample or vice versa. Further measurements for the confirmation of bulk superconductivity on variously synthesized samples are underway. Our results on the present LK-99 sample, being synthesized at 925$^\circ$C, as of now do not approve the appearance of bulk superconductivity at room temperature. Further studies with different heat treatments are though, yet underway.Comment: Short Commun.: 8pages Text + Figs: Comments/suggestion Welcom

Topological Superconductor Sn4Au: A first principle study

Topological semimetals such as Weyl or Dirac semimetal with superconductivity have emerged as a new class of topological materials to realize and study Majorana Fermion in its intrinsic form. This article reports the Density Functional Theory (DFT) calculated bulk electronic band structure of recently discovered topological superconductor candidate Sn4Au. This study is further extended to the calculation of Z2 invariants. The Fermi surfaces corresponding to the bands which are responsible for non-trivial band topology along with the surface states are also mapped. The complete study suggests that Sn4Au is a topological semimetal. On Sn4Au, it is the first report in the literature showing the non-trivial band topology based on first-principle calculations.Comment: 19 Pages Text + Figs: SUST - Special issue: Superconductivity Research in Indi

Weak Antilocalization and topological edge states in PdSn4_4

Here we report, the successful synthesis of single crystals of topological semimetal (TSM) candidate, PdSn$_4$ using the self-grown route. The synthesized crystal is well characterized through X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and X-ray photoelectron spectroscopy (XPS). Detailed Rietveld analysis of the powder XRD pattern of PdSn$_4$ confirmed the same to crystallize in the Aea2 space group instead of reported Ccce. A large magnetoresistance (MR) along with Subnikov-de Haas oscillations have been observed in magnetotransport measurements at 2K. The presence of a weak antilocalization (WAL) effect in synthesized PdSn$_4$ crystal is confirmed and analyzed using Hikami Larkin Nagaoka (HLN) formalism, being applied on magnetoconductivity of the same at the low magnetic field. An extended Kohler rule is implemented on MR data, to determine the role of the scattering process and temperature-dependent carrier density on transport phenomenon in PdSn$_4$. Further, the non-trivial band topology and presence of edge states are shown through density functional theory (DFT) based theoretical calculations. All calculations are performed considering the Aea2 space group symmetry. The calculated Z2 invariants suggest the presence of weak topological insulating properties in PdSn$_4$. Clear evidence of topological edge states at the $\Gamma$ point is visible in calculated edge state spectra. This is the first report on PdSn$_4$, showing the presence of SdH oscillation in magneto transport measurement.Comment: 26 PAGES TEXT + FIGS. REVISED J. APPL. PHYS. 202

Dynamic classification using case-specific training cohorts outperforms static gene expression signatures in breast cancer

The molecular diversity of breast cancer makes it impossible to identify prognostic markers that are applicable to all breast cancers. To overcome limitations of previous multigene prognostic classifiers, we propose a new dynamic predictor: instead of using a single universal training cohort and an identical list of informative genes to predict the prognosis of new cases, a case-specific predictor is developed for each test case. Gene expression data from 3,534 breast cancers with clinical annotation including relapse-free survival is analyzed. For each test case, we select a case-specific training subset including only molecularly similar cases and a case-specific predictor is generated. This method yields different training sets and different predictors for each new patient. The model performance was assessed in leave-one-out validation and also in 325 independent cases. Prognostic discrimination was high for all cases (n = 3,534, HR = 3.68, p = 1.67 E-56). The dynamic predictor showed higher overall accuracy (0.68) than genomic surrogates for Oncotype DX (0.64), Genomic Grade Index (0.61) or MammaPrint (0.47). The dynamic predictor was also effective in triple-negative cancers (n = 427, HR = 3.08, p = 0.0093) where the above classifiers all failed. Validation in independent patients yielded similar classification power (HR = 3.57). The dynamic classifier is available online at http://www.recurrenceonline.com/?q=Re_training. In summary, we developed a new method to make personalized prognostic prediction using case-specific training cohorts. The dynamic predictors outperform static models developed from single historical training cohorts and they also predict well in triple-negative cancers

Detailed structural and topological analysis of SnBi2Te4 single crystal

We report herein the successful synthesis of the topological material SnBi2Te4 in single-crystal form. Phase purity and unidirectional growth are evident from X-ray diffraction (XRD) patterns acquired from a powdered sample and a crystal flake. The crystalline morphology has also been visualized by acquiring a field-emission scanning electron microscope (FESEM) image. The crystal has been thoroughly characterized by means of Raman spectroscopy and X ray photoelectron spectroscopy (XPS) measurements. The topological properties of SnBi2Te4 have been probed through magneto-transport measurements. SnBi2Te4 has been found to exhibit a small but non-saturating magneto-resistance (MR) up to 12 T. The low-field magnetoconductivity (MC) of SnBi2Te4 at 2 K can be well explained through the Hikami Larkin Nagaoka (HLN) formalism, which confirms the presence of a weak anti-localization (WAL) effect in its crystal. Moreover, the non-trivial topological character has been evidenced through first-principles calculations using density functional theory (DFT), with and without spin-orbit coupling (SOC) protocols. A significant change in the bulk electronic band structure is observed upon the inclusion of SOC parameters, signifying the topological properties of SnBi2Te4. Its topological non-trivial character has also been verified through the calculation of Z2 invariants and the surface states spectrum in the (111) plane.Comment: 24 Pages TEXT + Figs: J. Phys. Chem. Solid

Drastic suppression of CDW (charge density wave) by Pd addition in TiSe2

TiSe2 is a known Topological semimetal (TSM) having both the semi-metallic and topological characters simultaneously and the Charge density wave (CDW) at below 200K. In the current short article, we study the impact of Pd addition on the CDW character of TiSe2 and the possible induction of superconductivity at low temperatures. Bulk samples of TiSe2 and Pd0.1TiSe2 are synthesized by solid-state reaction route, which is further characterized by powder X-ray diffraction (PXRD) and field emission scanning electron microscopy (FESEM), respectively, for their structural and micro-structural details. The vibrational modes of both samples are being analyzed by Raman spectroscopy, showing the occurrence of both A1g and Eg modes. CDW of pure TiSe2 seen at around 200K in electrical transport measurements, in terms of sharp semi-metallic to metallic transition peak with hysteresis in cooling/warming cycles is not seen in Pd0.1TiSe2, and rather a near metallic transport is seen down to 2K. Although superconductivity is not seen down to 2K, the CDW transition is seemingly completely suppressed in Pd0.1TiSe2. Pd addition in TiSe2 suppresses CDW drastically. Trials are underway to induce superconductivity in Pd-added TiSe2. Density functional theory (DFT) calculations show primary evidence of suppression of CDW by adding Pd in TiSe2 due to an increase in the density of states.Comment: 11 Pages Text + Figs: Accepted J. Sup. Novel Ma

Insight Into Molecular Determinants of T3 vs T4 Recognition From Mutations in Thyroid Hormone Receptor α and β.

CONTEXT: The two major forms of circulating thyroid hormones (THs) are T3 and T4. T3 is regarded as the biologically active hormone because it binds to TH receptors (TRs) with greater affinity than T4. However, it is currently unclear what structural mechanisms underlie this difference in affinity. OBJECTIVE: Prompted by the identification of a novel M256T mutation in a resistance to TH (RTH)α patient, we investigated Met256 in TRα1 and the corresponding residue (Met310) in TRβ1, residues previously predicted by crystallographic studies in discrimination of T3 vs T4. METHODS: Clinical characterization of the RTHα patient and molecular studies (in silico protein modeling, radioligand binding, transactivation, and receptor-cofactor studies) were performed. RESULTS: Structural modeling of the TRα1-M256T mutant showed that distortion of the hydrophobic niche to accommodate the outer ring of ligand was more pronounced for T3 than T4, suggesting that this substitution has little impact on the affinity for T4. In agreement with the model, TRα1-M256T selectively reduced the affinity for T3. Also, unlike other naturally occurring TRα mutations, TRα1-M256T had a differential impact on T3- vs T4-dependent transcriptional activation. TRα1-M256A and TRβ1-M310T mutants exhibited similar discordance for T3 vs T4. CONCLUSIONS: Met256-TRα1/Met310-TRβ1 strongly potentiates the affinity of TRs for T3, thereby largely determining that T3 is the bioactive hormone rather than T4. These observations provide insight into the molecular basis for underlying the different affinity of TRs for T3 vs T4, delineating a fundamental principle of TH signaling