An air-stable N-heterocyclic carbene iminoxyl borate radical zwitterion

A remarkably stable radical zwitterion derived from N-heterocyclic carbene nitric oxide and B(C6F5)(3) is reported. The presented radical was generated by steric and electronic protection of the nitric oxide moiety using B(C6F5)(3), which secured its stability toward air and moisture. An analogous yet less stable radical derived from C(C6H5)(3)(+) is also synthesized and characterized.111Ysciescopu

Pressure effects on the superconducting thin film Ba1−x_{1-x}Kx_{x}Fe2_{2}As2_{2}

We report electrical resistivity measurements on a high-quality Ba$_{1-x}$K$_{x}$Fe$_{2}$As$_{2}$ thin film ($x=0.4$) under pressure. The superconducting transition temperature (=39.95 K) of the optimally-doped thin film shows a dome shape with pressure, reaching a maximal value 40.8 K at 11.8 kbar. The unusually high superconducting transition temperature and its anomalous pressure dependence are ascribed to a lattice mismatch between the LaAlO$_3$ substrate and the thin film. The local temperature exponent of the resistivity ($n=d\text{ln}\Delta\rho/d\text{ln}T$) shows a funnel shape around the optimal pressure, suggesting that fluctuations associated with the anomalous normal state are responsible for high-temperature superconductivity.Comment: To appear in Appl. Phys. Let

Nickel-Mediated Oxidative Fluorination for PET with Aqueous [18F^{18}F] Fluoride

A one-step oxidative fluorination for carbon–fluorine bond formation from well-defined nickel complexes with oxidant and aqueous fluoride is presented, which enables a straightforward and practical $^{18}F$ late-stage fluorination of complex small molecules with potential for PET imaging.Chemistry and Chemical Biolog

Fast Motion Deblurring Using Sensor-Aided Motion Trajectory Estimation

This paper presents an image deblurring algorithm to remove motion blur using analysis of motion trajectories and local statistics based on inertial sensors. The proposed method estimates a point-spread-function (PSF) of motion blur by accumulating reweighted projections of the trajectory. A motion blurred image is then adaptively restored using the estimated PSF and spatially varying activity map to reduce both restoration artifacts and noise amplification. Experimental results demonstrate that the proposed method outperforms existing PSF estimation-based motion deconvolution methods in the sense of both objective and subjective performance measures. The proposed algorithm can be employed in various imaging devices because of its efficient implementation without an iterative computational structure

A Dinuclear Palladium Catalyst for α\alpha-Hydroxylation of Carbonyls with O2O_2

A chemo- and regioselective $\alpha$-hydroxylation reaction of carbonyl compounds with molecular oxygen as oxidant is reported. The hydroxylation reaction is catalyzed by a dinuclear Pd(II) complex, which functions as an oxygen transfer catalyst, reminiscent of an oxygenase. The development of this oxidation reaction was inspired by discovery and mechanism evaluation of previously unknown Pd(III)−Pd(III) complexes.Chemistry and Chemical Biolog

Presure-Induced Superconducting State of Antiferromagnetic CaFe2_2As2_2

The antiferromagnet CaFe$_2$As$_2$ does not become superconducting when subject to ideal hydrostatic pressure conditions, where crystallographic and magnetic states also are well defined. By measuring electrical resistivity and magnetic susceptibility under quasi-hydrostatic pressure, however, we find that a substantial volume fraction of the sample is superconducting in a narrow pressure range where collapsed tetragonal and orthorhombic structures coexist. At higher pressures, the collapsed tetragonal structure is stabilized, with the boundary between this structure and the phase of coexisting structures strongly dependent on pressure history. Fluctuations in magnetic degrees of freedom in the phase of coexisting structures appear to be important for superconductivity.Comment: revised (6 pages, 5 figures) - includes additional experimental result

Silver-Mediated Trifluoromethoxylation of Aryl Stannanes and Arylboronic Acids

A silver-mediated cross-coupling of trifluoromethoxide with aryl stannanes and arylboronic acids to give aryl trifluoromethyl ethers is reported. This is the first report of a transition-metal-mediated $C_{aryl}–OCF_3$ bond formation.Chemistry and Chemical Biolog

Pressure dependence of upper critical fields in FeSe single crystals

We investigate the pressure dependence of the upper critical fields ({\mu}$_0$$H$$_{c2}$) for FeSe single crystals with pressure up to 2.57 GPa. The superconducting (SC) properties show a disparate behavior across a critical pressure where the pressure-induced antiferromagnetic phase coexists with superconductivity. The magnetoresistance for $H//ab$ and $H//c$ is very different: for $H//c$, magnetic field induces and enhances a hump in the resistivity close to the $T_c$ for pressures higher than 1.2 GPa, while it is absent for $H//ab$. Since the measured {\mu}$_0$$H$$_{c2}$ for FeSe samples is smaller than the orbital limited upper critical field ($H$$^{orb}$$_{c2}$) estimated by the Werthamer Helfand and Hohenberg (WHH) model, the Maki parameter ({\alpha}) related to Pauli spin-paramagnetic effects is additionally considered to describe the temperature dependence of {\mu}$_0$$H$$_{c2}$($T$). Interestingly, the {\alpha} value is hardly affected by pressure for $H//ab$, while it strongly increases with pressure for $H//c$. The pressure evolution of the {\mu}$_0$$H$$_{c2}$(0)s for the FeSe single crystals is found to be almost similar to that of $T_c$($P$), suggesting that the pressure-induced magnetic order adversely affects the upper critical fields as well as the SC transition temperature.Comment: 23 pages, 6 figures, 1 tabl

Performances Monitoring and Analysis for KASS

The Korea Augmentation Satellite System (KASS) is the future SBAS of the Republic of Korea. It is developed by the Korea Aerospace research Institute (KARI) for the government of the Republic of Korea, and Thales Alenia Space is the industry prime contractor of this development. The function of the KASS is to decompose all possible range error sources and to distribute corrections and/or alerts to its users by means of geostationary satellites. The KASS Processing Station (KPS) is the component of KASS in charge of computing the orbit, clock and ionosphere correction and alert information (below ‘Navigation Overlay Frame’, NOF) using data from a set of reference stations. The KPS is composed of two independent elements: the Processing Set (PS) and the Check Set (CS). The first element is responsible of computing the complete navigation context for the GNSS constellation (orbits and clock) and the ionosphere model, then to prepare and send the NOF to be broadcast to the users. The second element acts as a super user by applying the NOF to the GPS messages checking that this is consistent with an independent set of measurement to control and insure the integrity. The KPS-PS component plays a key role in the KASS performance achievement where the APV-1 service level is required. To feed the KPS, the KASS has specific KASS Reference Station (KRS) located on the Rep. of Korea land masses. Compared to other SBAS, this leads to a very concentrated station network. This particularity makes a specific algorithm adaptation of the KPS-PS necessary, as compared to the EGNOS solution, to provide the desired APV-1 performance. These adaptations regard both orbit determination and all the more ionosphere corrections due to the very low number of Ionosphere Grid Points (IPG) that need be modeled and monitored. To cope with these KASS specificities, Thales Alenia Space has designed, developed and qualified a new complete real time navigation algorithm chain that provides MOPS-compliant NOF messages. The ionosphere model is different from the EGNOS one that favors a local analysis counter to a global approach as the TRIN model [2] used in EGNOS. This new algorithm chain provides the specified APV-1 performance, particularly in the case of strong ionosphere activity, with a very good level of integrity margin. This paper presents the overall KASS system architecture as well as the results obtained using this new algorithm chain under different ionosphere contexts. The APV-1 service availability level is presented and the maximum of safety index on each monitored IGP and satellite is discussed