Temperature- and magnetic-field-dependent resistivity of MgB2 sintered at high temperature and high pressure condition

We report the temperature- and magnetic-field-dependent resistivity of MgB2 sintered at high temperature and high pressure condition. The superconducting transition width for the resistivity measurement was about 0.4 K, and the low-field magnetization showed a sharp superconducting transition with a transition width of about 1 K. The resistivity in the normal state roughly followed T^2 behavior with smaller residual resistivity ratio (RRR) of 3 over broad temperature region above 100 K rather than reported T^3 behavior with larger RRR value of ~ 20 in the samples made at lower pressures. Also, the resistivity did not change appreciably with the applied magnetic field, which was different from previous report. These differences were discussed with the microscopic and structural change due to the high-pressure sintering.Comment: 2 pages, 3 figures. Accepted by Physica

Meteorological and chemical factors controlling ozone formation in Seoul during MAPS-Seoul 2015

To understand the chemical mechanisms of controlling factors in ozone (O3) formation in early summer in Seoul, a comprehensive study encompassing measurement and modeling was conducted under the Megacity Air Pollution Study-Seoul (MAPS-Seoul) campaign. From May 18 to June 12, 2015, O3 and peroxyacetyl nitrate (PAN) were measured, along with their precursors, including NOx and volatile organic compounds (VOCs), at the Korea Institute of Science and Technology, located in northeast Seoul. VOCs were sampled in a canister twice a day (at 09:30 and 15:00) and analyzed via gas chromatography. The meteorological conditions and chemical regimes of the air masses were clearly distinguished during the study period. In May, NOx concentrations were higher with more pronounced diurnal cycles of precursors and O3 under constant westerly winds. By contrast, stagnant conditions developed in June, which reduced the inflow of primary emissions from the downtown area but increased the influence from the neighboring forest under high temperatures. As a result, the ratio of O3 to odd oxygen was higher in June, indicating a less efficient removal of O3 by NOx. In the same context, the air mass was chemically more aged with a higher NO2/NOx ratio and enhanced OH reactivity of oxygenated and biogenic VOCs in June. The overall measurement results suggest that O3 formation is slightly more sensitive to VOCs than to NOx in Seoul during this season, when O3 concentrations are the highest of the year

Aluthge iterations of weighted translation semigroups

AbstractThe problem whether Aluthge iteration of bounded operators on a Hilbert space H is convergent was introduced in [I. Jung, E. Ko, C. Pearcy, Aluthge transforms of operators, Integral Equations Operator Theory 37 (2000) 437–448]. And the problem whether the hyponormal operators on H with dimH=∞ has a convergent Aluthge iteration under the strong operator topology remains an open problem [I. Jung, E. Ko, C. Pearcy, The iterated Aluthge transform of an operator, Integral Equations Operator Theory 45 (2003) 375–387]. In this note we consider symbols with a fractional monotone property which generalizes hyponormality and 2-expansivity on weighted translation semigroups, and prove that if {St} is a weighted translation semigroup whose symbol has the fractional monotone property, then its Aluthge iteration converges to a quasinormal operator under the strong operator topology

Staggered Currents in the Vortex Core

We study the electronic structure of the vortex core in the cuprates using the U(1) slave-boson mean-field wavefunctions and their Gutzwiller projection. We conclude that there exists local orbital antiferromagnetic order in the core near optimal doping. We compare the results with that of BCS theory and analyze the spatial dependence of the local tunneling density of states.Comment: 4 pages, 3 figure

Scanning tunneling spectroscopic studies of the pairing state of cuprate superconductors

Quasiparticle tunneling spectra of both hole-doped (p-type) and electron-doped (n-type) cuprates are studied using a low-temperature scanning tunneling microscope. The results reveal that neither the pairing symmetry nor the pseudogap phenomenon is universal among all cuprates, and that the response of n-type cuprates to quantum impurities is drastically different from that of the p-type cuprates. The only ubiquitous features among all cuprates appear to be the strong electronic correlation and the nearest-neighbor antiferromagnetic Cu2+-Cu2+ coupling in the CuO2 planes