Correlated Electronic Structures and the Phase Diagram of Hydrocarbon-based Superconductors

We have investigated correlated electronic structures and the phase diagram of electron-doped hydrocarbon molecular solids, based on the dynamical mean-field theory. We have found that the ground state of hydrocarbon-based superconductors such as electron-doped picene and coronene is a multi-band Fermi liquid, while that of non-superconducting electron-doped pentacene is a single-band Fermi liquid in the proximity of the metal-insulator transition. The size of the molecular orbital energy level splitting plays a key role in producing the superconductivity of electron-doped hydrocarbon solids. The multi-band nature of hydrocarbon solids would boost the superconductivity through the enhanced density of states at the Fermi level.X11910sciescopu

Physical properties of transparent perovskite oxides (Ba,La)SnO3 with high electrical mobility at room temperature

Transparent electronic materials are increasingly in demand for a variety of optoelectronic applications. BaSnO3 is a semiconducting oxide with a large band gap of more than 3.1 eV. Recently, we discovered that La doped BaSnO3 exhibits unusually high electrical mobility of 320 cm^2(Vs)^-1 at room temperature and superior thermal stability at high temperatures [H. J. Kim et al. Appl. Phys. Express. 5, 061102 (2012)]. Following that work, we report various physical properties of (Ba,La)SnO3 single crystals and films including temperature-dependent transport and phonon properties, optical properties and first-principles calculations. We find that almost doping-independent mobility of 200-300 cm^2(Vs)^-1 is realized in the single crystals in a broad doping range from 1.0x10^19 to 4.0x10^20 cm^-3. Moreover, the conductivity of ~10^4 ohm^-1cm^-1 reached at the latter carrier density is comparable to the highest value. We attribute the high mobility to several physical properties of (Ba,La)SnO3: a small effective mass coming from the ideal Sn-O-Sn bonding, small disorder effects due to the doping away from the SnO2 conduction channel, and reduced carrier scattering due to the high dielectric constant. The observation of a reduced mobility of ~70 cm^2(Vs)^-1 in the film is mainly attributed to additional carrier-scatterings which are presumably created by the lattice mismatch between the substrate SrTiO3 and (Ba,La)SnO3. The main optical gap of (Ba,La)SnO3 single crystals remained at about 3.33 eV and the in-gap states only slightly increased, thus maintaining optical transparency in the visible region. Based on these, we suggest that the doped BaSnO3 system holds great potential for realizing all perovskite-based, transparent high-frequency high-power functional devices as well as highly mobile two-dimensional electron gas via interface control of heterostructured films.Comment: 31 pages, 7 figure

Optical Probing of Electronic Interaction between Graphene and Hexagonal Boron Nitride

Even weak van der Waals (vdW) adhesion between two-dimensional solids may perturb their various materials properties owing to their low dimensionality. Although the electronic structure of graphene has been predicted to be modified by the vdW interaction with other materials, its optical characterization has not been successful. In this report, we demonstrate that Raman spectroscopy can be utilized to detect a few % decrease in the Fermi velocity (vF) of graphene caused by the vdW interaction with underlying hexagonal boron nitride (hBN). Our study also establishes Raman spectroscopic analysis which enables separation of the effects by the vdW interaction from those by mechanical strain or extra charge carriers. The analysis reveals that spectral features of graphene on hBN are mainly affected by change in vF and mechanical strain, but not by charge doping unlike graphene supported on SiO2 substrates. Graphene on hBN was also found to be less susceptible to thermally induced hole doping.Comment: 19 pages, 4 figure

Clinical implications of correlation between peripheral eosinophil count and serum levels of IL-5 and tryptase in acute eosinophilic pneumonia

SummaryBackgroundThe peripheral eosinophil count (PEC) tends to increase during the course of acute eosinophilic pneumonia (AEP), and an initially elevated PEC is associated with milder disease. However, there is a lack of data regarding these phenomena and inflammatory process of AEP.MethodsWe prospectively evaluated serial changes in serum interleukin (IL)-5 levels and the correlation between the initial level of IL-5 and the PEC to investigate whether the initial PEC indicates a resolving state of inflammation. We also evaluated serum tryptase levels to investigate the possibility of involvement of mast cell activity in AEP.ResultsTwenty-one AEP patients were included, and all patients improved within 10 days after corticosteroid treatment. The median initial serum IL-5 level among all patients was 561.0 pg/mL, which decreased to zero at 10 days of follow-up (n = 15, P < 0.001). The median initial serum tryptase level (detectable in 20 of 21 patients) was 3.7 ng/mL and decreased to a median of 1.1 ng/mL at 10 days of follow-up (n = 15, P < 0.001). The initial serum IL-5 and C-reactive protein levels were positively correlated (P = 0.009, r = 0.556), and the initial serum IL-5 level was inversely correlated with the initial PEC (P = 0.004, r = −0.603).ConclusionsOur data suggest that IL-5 is an important cytokine involved in the recruitment of eosinophils from peripheral blood into the lungs, that an initially elevated PEC is associated with a resolving state of inflammation, and that mast cells are potentially involved in the inflammatory process of AEP

Electromagnet Weight Reduction in a Magnetic Levitation System for Contactless Delivery Applications

This paper presents an optimum design of a lightweight vehicle levitation electromagnet, which also provides a passive guide force in a magnetic levitation system for contactless delivery applications. The split alignment of C-shaped electromagnets about C-shaped rails has a bad effect on the lateral deviation force, therefore, no-split positioning of electromagnets is better for lateral performance. This is verified by simulations and experiments. This paper presents a statistically optimized design with a high number of the design variables to reduce the weight of the electromagnet under the constraint of normal force using response surface methodology (RSM) and the kriging interpolation method. 2D and 3D magnetostatic analysis of the electromagnet are performed using ANSYS. The most effective design variables are extracted by a Pareto chart. The most desirable set is determined and the influence of each design variable on the objective function can be obtained. The generalized reduced gradient (GRG) algorithm is adopted in the kriging model. This paper’s procedure is validated by a comparison between experimental and calculation results, which shows that the predicted performance of the electromagnet designed by RSM is in good agreement with the simulation results

Menthol Enhances an Antiproliferative Activity of 1α,25-Dihydroxyvitamin D3 in LNCaP Cells

1α,25-dihydroxyvitamin D3 [1α,25(OH)2D3], the most active form of vitamin D3, and its analogues have therapeutic benefits for prostate cancer treatment. However, the development of hypercalcemia is an obstacle to clinical applications of 1α,25(OH)2D3 for cancer therapy. In this study, we provide evidence that menthol, a key component of peppermint oil, increases an anti-proliferation activity of 1α,25(OH)2D3 in LNCaP prostate cancer cells. We found that menthol per se does not exhibit antiproliferative activity, but it is able to enhance 1α,25(OH)2D3-mediated growth inhibition in LNCaP cells. Fluorometric assays using Fura-2 showed that 1α,25(OH)2D3 does not induce acute Ca2+ response, whereas menthol evokes an increase in [Ca2+]i, which suggests that cross-talks of menthol-induced Ca2+ signaling with 1α,25(OH)2D3-mediated growth inhibition pathways. In addition, Western blot analysis revealed that 1α,25(OH)2D3 and menthol cooperatively modulate the expression of bcl-2 and p21 which provides the insight into the molecular mechanisms underlying the enhanced 1α,25(OH)2D3-mediated growth inhibition by menthol. Thus, our findings suggest that menthol may be a useful natural compound to enhance therapeutic effects of 1α,25(OH)2D3

Optimal Shape Design of the S-Shaped Subsonic Intake Using NURBS

A parallelized design optimization approach is presented for a subsonic S-shaped intake using aerodynamic sensitivity analysis. Two-equation turbulence model is adopted to predict the strong counter vortices in the S-shaped duct more precisely. Sensitivity analysis is performed for the three-dimensional Navier-Stokes equations coupled with two-equation turbulence models using a discrete adjoint method. For code validation, the result of the flow solver is compared with experiment data and bench marking data of other computation researches. To study the influence of turbulence models and grid refinement in the duct flow analysis, the results using several turbulence models are compared with each other on various grid systems. The adjoint variable code is validated by comparison with the complex step derivative results. And to guarantee a sufficient design space, NURBS equations are applied as a new shape function to modify the duct geometry freely. The capability and the efficiency of the present design tools are successfully demonstrated in three-dimensional subsonic inlet flow analysis and design optimization.OAIID:oai:osos.snu.ac.kr:snu2005-01/104/0000004648/33SEQ:33PERF_CD:SNU2005-01EVAL_ITEM_CD:104USER_ID:0000004648ADJUST_YN:NEMP_ID:A001138DEPT_CD:446CITE_RATE:0FILENAME:Optimal Shape Design of the S-Shaped Subsonic Intake Using NURBS.pdfDEPT_NM:기계항공공학부EMAIL:[email protected]: