Recent Advances in Cross Aldol Reactions

The aldol reaction plays an important role in organic synthesis and provides very useful synthetic tools for stereoselective and asymmetric carbon-carbon bond formations. Four types of aldol reactions developed in our laboratory are discussed

Suzaku Discovery of a Hard X-Ray Tail in the Persistent Spectra from the Magnetar 1E 1547.0-5408 during its 2009 Activity

The fastest-rotating magnetar 1E 1547.0-5408 was observed in broad-band X-rays with Suzaku for 33 ks on 2009 January 28-29, 7 days after the onset of its latest bursting activity. After removing burst events, the absorption-uncorrected 2-10 keV flux of the persistent emission was measured with the XIS as 5.7e-11 ergs cm-2 s-1, which is 1-2 orders of magnitude higher than was measured in 2006 and 2007 when the source was less active. The persistent emission was also detected significantly with the HXD in >10 keV up to at least ~110 keV, with an even higher flux of 1.3e-10 ergs cm-2 s-1 in 20-100 keV. The pulsation was detected at least up to 70 keV at a period of 2.072135+/-0.00005 s, with a deeper modulation than was measured in a fainter state. The phase-averaged 0.7-114 keV spectrum was reproduced by an absorbed blackbody emission with a temperature of 0.65+/-0.02 keV, plus a hard power-law with a photon index of ~1.5. At a distance of 9 kpc, the bolometric luminosity of the blackbody and the 2-100 keV luminosity of the hard power-law are estimated as (6.2+/-1.2)e+35 ergs s-1 and 1.9e+36 ergs s-1, respectively, while the blackbody radius becomes ~5 km. Although the source had not been detected significantly in hard X-rays during the past fainter states, a comparison of the present and past spectra in energies below 10 keV suggests that the hard component is more enhanced than the soft X-ray component during the persistent activity.Comment: 12 pages, 7 figures, PASJ Vol.62 No.2 accepte

A NuSTAR study of the 55 ks hard X-ray pulse-phase modulation in the magnetar 4U 0142+61

Archival NuSTAR data of the magnetar 4U 0142+61, acquired in 2014 March for a total time span of 258 ks, were analyzed. This is to reconfirm the 55 ks modulation in the hard X-ray pulse phases of this source, found with a Suzaku observation in 2009 (Makishima et al., 2014, Phys. Rev. Lett., 112, 171102). Indeed, the 10–70 keV X-ray pulsation, detected with NuSTAR at 8.68917 s, was found to be also phase-modulated (at >98% confidence) at the same ∼55 ks period, or half that value. Furthermore, a brief analysis of another Suzaku data set of 4U 0142+61, acquired in 2013, reconfirmed the same 55 ks phase modulation in the 15–40 keV pulses. Thus, the hard X-ray pulse-phase modulation was detected with Suzaku (in 2009 and 2013) and NuSTAR (in 2014) at a consistent period. However, the modulation amplitude varied significantly; A ∼ 0.7 s with Suzaku (in 2009), A ∼ 1.2 s with Suzaku (in 2013), and A ∼ 0.17 s with NuSTAR. In addition, the phase modulation properties detected with NuSTAR differed considerably between the first 1/3 and the latter 2/3 of the observation. In energies below 10 keV, the pulse-phase modulation was not detected with either Suzaku or NuSTAR. These results reinforce the view of Makishima et al. (2014, Phys. Rev. Lett., 112, 171102); the neutron star in 4U 0142+61 keeps free precession, under a slight axial deformation due probably to ultra-high toroidal magnetic fields of ∼10^(16) G. The wobbling angle of precession should remain constant, but the pulse-phase modulation amplitude varies on time scales of months to years, presumably as asymmetry of the hard X-ray emission pattern around the star’s axis changes

Magnetar Broadband X-ray Spectra Correlated with Magnetic Fields: Suzaku Archive of SGRs and AXPs Combined with NuSTAR, Swift, and RXTE

The 1–70 keV persistent spectra of 15 magnetars, observed with Suzaku from 2006 to 2013, were studied as a complete sample. Combined with early NuSTAR observations of four hard X-ray emitters, nine objects showed a hard power-law emission dominating at ≳ 10 keV with the 15–60 keV flux of ~1–11 x 10^(-11) erg s^(−1) cm^(−2). The hard X-ray luminosity L_h, relative to that of a soft-thermal surface radiation L_s, tends to become higher toward younger and strongly magnetized objects. Their hardness ratio, updated from a previous study and defined as ξ = L_h/L_s, is correlated with the measured spin-down rate P as ξ = 0.62 x (P/10^(-11)s s^(-1))^(0.72), corresponding to positive and negative correlations with the dipole field strength B_d (ξ ∝ B^(1.41)_d) and the characteristic age τ_c (ξ ∝ τ_c^(-0.68)), respectively. Among our sample, five transients were observed during X-ray outbursts, and the results are compared with their long-term 1–10 keV flux decays monitored with Swift/XRT and RXTE/PCA. Fading curves of three bright outbursts are approximated by an empirical formula used in the seismology, showing a ~10–40 day plateau phase. Transients show the maximum luminosities of L_s ~ 10^(35) erg s^(−1), which are comparable to those of persistently bright ones, and fade back to ≾10^(32) erg s^(−1). Spectral properties are discussed in the framework of the magnetar hypothesis

Radioligand Assay-Based Detection of Antibodies against SARS-CoV-2 in Hospital Workers Treating Patients with Severe COVID-19 in Japan.

This study aimed to clarify whether infection by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is prevalent among the staff of a hospital providing treatment to patients with severe coronavirus disease 2019 (COVID-19) using radioligand assay (RLA). One thousand samples from the staff of a general hospital providing treatment to patients with severe COVID-19 were assayed for SARS-CoV-2 nucleocapsid protein (N) IgG using RLA. Nine patients with COVID-19 who had been treated in inpatient settings and had already recovered were used as control subjects, and 186 blood donor samples obtained more than 10 years ago were used as negative controls. Four of the 1000 samples showed apparently positive results, and approximately 10 or more samples showed slightly high counts. Interestingly, a few among the blood donor samples also showed slightly high values. To validate the results, antibody examinations using ELISA and neutralizing antibody tests were performed on 21 samples, and chemiluminescence immunoassay (CLIA) was performed on 201 samples, both resulting in a very high correlation. One blood donor sample showed slightly positive results in both RLA and CLIA, suggesting a cross-reaction. This study showed that five months after the pandemic began in Japan, the staff of a general hospital with a tertiary emergency medical facility had an extremely low seroprevalence of the antibodies against SARS-CoV-2. Further investigation will be needed to determine whether the slightly high results were due to cross-reactions or a low titer of anti-SARS-CoV-2 antibodies. The quantitative RLA was considered sensitive enough to detect low titers of antibodies

Suzaku Observation of the Anomalous X-ray Pulsar CXOU J164710.2--455216

Suzaku TOO observation of the anomalous X-ray pulsar CXOU J164710.2-455216 was performed on 2006 September 23--24 for a net exposure of 38.8 ks. During the observation, the XIS was operated in 1/8 window option to achieve a time resolution of 1 s. Pulsations are clearly detected in the XIS light curves with a barycenter corrected pulse period of 10.61063(2) s. The XIS pulse profile shows 3 peaks of different amplitudes with RMS fractional amplitude of ~11% in 0.2--6.0 keV energy band. Though the source was observed with the HXD of Suzaku, the data is highly contaminated by the nearby bright X-ray source GX 340+0 which was in the HXD field of view. The 1-10 keV XIS spectra are well fitted by two blackbody components. The temperatures of two blackbody components are found to be 0.61+/-0.01 keV and 1.22+/-0.06 keV and the value of the absorption column density is 1.73+/-0.03 x 10^{22} atoms cm^{-2}. The observed source flux in 1-10 keV energy range is calculated to be 2.6 x 10^{-11} ergs cm^{-2} s^{-1} with significant contribution from the soft blackbody component (kT = 0.61 keV). Pulse phase resolved spectroscopy of XIS data shows that the flux of the soft blackbody component consists of three narrow peaks, whereas the flux of the other component shows a single peak over the pulse period of the AXP. The blackbody radii changes between 2.2-2.7 km and 0.28-0.38 km (assuming the source distance to be 5 kpc) over pulse phases for the soft and hard components, respectively. The details of the results obtained from the timing and spectral analysis is presented.Comment: 16 pages, 9 figures, Accepted for publication in Publications of the Astronomical Society of Japan (PASJ

In Orbit Timing Calibration of the Hard X-Ray Detector on Board Suzaku

The hard X-ray detector (HXD) on board the X-ray satellite Suzaku is designed to have a good timing capability with a 61 $\mu$s time resolution. In addition to detailed descriptions of the HXD timing system, results of in-orbit timing calibration and performance of the HXD are summarized. The relative accuracy of time measurements of the HXD event was confirmed to have an accuracy of $1.9\times 10^{-9}$ s s$^{-1}$ per day, and the absolute timing was confirmed to be accurate to 360 $\mu$s or better. The results were achieved mainly through observations of the Crab pulsar, including simultaneous ones with RXTE, INTEGRAL, and Swift.Comment: Accepted for publication on PASJ Vol.60, SP-1, 200