Silylation of alcohols has generally been known to take place at the sterically most accessible less‐hindered hydroxy group. Herein, the catalyst‐controlled substrate‐selective silylation of primary ...alcohols, in which the selectivity was controlled independently of the innate reactivity of the hydroxy group, based on the steric environment, is reported. The chain‐length‐selective silylation of 1,n‐amino alcohol derivatives was achieved and 1,5‐amino alcohol derivatives showed outstandingly high reactivity in the presence of analogues with a shorter or longer chain length under catalyst‐controlled conditions. A highly substrate‐selective catalytic silylation of pentanol analogues was also developed, in which the remote functionality at C(5) from the reacting hydroxy groups was effectively discriminated on silylation.
Precise molecular recognition of the substrate structure by catalyst 3 enabled substrate‐selective silylation of long‐chain primary alcohols. Silylation of A proceeded 11 times faster than that of B by recognition of a one‐carbon difference between primary alcohols A and B. Preferential silylation of A took place over that of C by a factor of 21 owing to discrimination of the remote functionality at C(5) from the reacting OH group at C(1).
We systematically investigate the near- to far-infrared (FIR) photometric properties of a nearly complete sample of local active galactic nuclei (AGNs) detected in the Swift/Burst Alert Telescope ...(BAT) all-sky ultra-hard X-ray (14-195 keV) survey. Out of 606 non-blazar AGNs in the Swift/BAT 70 month catalog at high galactic latitudes of , we obtain IR photometric data of 604 objects by cross-matching the AGN positions with catalogs from the WISE, AKARI, IRAS, and Herschel infrared observatories. We find a good correlation between the ultra-hard X-ray and mid-IR luminosities over five orders of magnitude ( ). Informed by previous measurements of the intrinsic spectral energy distribution of AGNs, we find FIR pure-AGN candidates whose FIR emission is thought to be AGN-dominated with low star-formation activity. We demonstrate that the dust covering factor decreases with the bolometric AGN luminosity, confirming the luminosity-dependent unified scheme. We also show that the completeness of the WISE color-color cut in selecting Swift/BAT AGNs increases strongly with 14-195 keV luminosity.
We present the first catalog and data release of the Swift-BAT AGN Spectroscopic Survey. We analyze optical spectra of the majority of the detected AGNs (77%, 642/836)based on their 14-195 keV ...emission in the 70-month Swift-BAT all-sky catalog. This includes redshift determination, absorption and emission-line measurements, and black hole mass and accretion rate estimates for the majority of obscured and unobscured AGNs (74%, 473/642), with 340 measured for the first time. With ∼90% of sources at , the survey represents a significant advance in the census of hard X-ray-selected AGNs in the local universe. In this first catalog paper, we describe the spectroscopic observations and data sets, and our initial spectral analysis. The FWHMs of the emission lines show broad agreement with the X-ray obscuration (∼94%), such that Sy 1-1.8 have cm−2, and Seyfert 2 have cm−2. Seyfert 1.9, however, show a range of column densities. Compared to narrow-line AGNs in the SDSS, the X-ray-selected AGNs have a larger fraction of dusty host galaxies ( ), suggesting that these types of AGN are missed in optical surveys. Using the O iii λ5007/Hβ and N ii λ6583/H emission-line diagnostic, about half of the sources are classified as Seyferts; ∼15% reside in dusty galaxies that lack an Hβ detection, but for which the upper limits on line emission imply either a Seyfert or LINER, are in galaxies with weak or no emission lines despite high-quality spectra, and a few percent each are LINERS, composite galaxies, H ii regions, or in known beamed AGNs.
The IceCube report of a excess of 13 5 neutrino events in the direction of the blazar TXS 0506+056 in 2014-2015 and the 2017 detection of a high-energy neutrino event, IceCube-170922A, during a ...gamma-ray flare from the same blazar, have revived the interest in scenarios for neutrino production in blazars. We perform comprehensive analyses on the long-term electromagnetic emission of TXS 0506+056 using optical, X-ray, and gamma-ray data from the All-Sky Automated Survey for Supernovae, the Neil Gehrels Swift Observatory, Monitor of All-sky X-ray Image, and the Fermi Large Area Telescope. We also perform numerical modeling of the spectral energy distributions (SEDs) in four epochs prior to 2017 with contemporaneous gamma-ray and lower-energy (optical and/or X-ray) data. We find that the multi-epoch SEDs are consistent with a hybrid leptonic scenario, where the gamma-rays are produced in the blazar zone via external inverse Compton scattering of accelerated electrons, and high-energy neutrinos are produced via the photomeson production process of co-accelerated protons. The multi-epoch SEDs can be satisfactorily explained with the same jet parameters and variable external photon density and electron luminosity. Using the maximal neutrino flux derived for each epoch, we put an upper limit of ∼0.4-2 on the muon neutrino number in 10 years of IceCube observations. Our results are consistent with the IceCube-170922A detection, which can be explained as an upper fluctuation from the average neutrino rate expected from the source, but in strong tension with the 2014-2015 neutrino flare.
A method for rotaxane synthesis by enlargement of the size of the terminal phenol group of the axle component by aromatic bromination has been developed. This method may be regarded as an end‐capping ...strategy involving the swelling of the phenol group at the axle terminal. The advantages of the present strategy include: ready availability of axle components with a variety of swelling precursors, wide product scope (19 examples given including a 3rotaxane), mild conditions for the swelling process, rich potential for the derivatization of the brominated rotaxanes, and possible release of the axle component by degradative dethreading of the thermally stable brominated rotaxanes under the basic conditions.
Enlargement of the size of the terminal phenol group of the axle component by aromatic bromination was found effective for rotaxane synthesis. The 19 examples given, including the formation of a 3rotaxane, illustrate the broad scope of the approach as well as the possible degradative release of the axle component by dethreading of the thermally stable brominated rotaxanes under the basic conditions.
Integrin activation by the intracellular adaptor proteins talin1 and kindlin-3 is essential for lymphocyte adhesion. These adaptors cooperatively control integrin activation through bidirectional ...(inside-out and outside-in) activation signals. Using single-molecule measurements, we revealed the distinct dynamics of talin1 and kindlin-3 interactions with the integrin LFA1 (αLβ2) and their functions in LFA1 activation and LFA1-mediated adhesion. The kinetics of talin1 binding to the tail of the β2 subunit corresponded to those of LFA1 binding to its ligand ICAM1. ICAM1 binding induced transient interactions between the membrane-proximal cytoplasmic region of the β2 subunit with an N-terminal domain of kindlin-3, leading to disruption of the association between the integrin subunits (the α/β clasp) and unbending of the ectodomains of the α/β heterodimer. These conformational changes promoted high-affinity talin1 binding to the β2 tail that required the talin rod domain and the actomyosin cytoskeleton. Inside-out signaling induced by the GTPase Rap1 did not markedly stabilize the binding of talin1 and kindlin-3 to LFA1. In contrast, ligand-induced outside-in signaling, the stabilization of open LFA1 conformers, or shear force substantially altered the dynamics of talin1 and kindlin-3 association with LFA1 and enhanced both Rap1 and LFA1 activation. In migrating lymphocytes, asymmetrical distribution of talin1 and kindlin-3 correlated with the maturation of LFA1 from a low-affinity conformation at the leading edge to a high-affinity conformation in the adherent mid-body. Our results suggest that kindlin-3 spatiotemporally mediates a positive feedback circuit of LFA1 activation to control dynamic adhesion and migration of lymphocytes.
We quantify the luminosity contribution of active galactic nuclei (AGNs) to the 12 m, mid-infrared (MIR; 5-38 m), and total IR (5-1000 m) emission in the local AGNs detected in the all-sky 70 month ...Swift/Burst Alert Telescope (BAT) ultrahard X-ray survey. We decompose the IR spectral energy distributions (SEDs) of 587 objects into the AGN and starburst components using templates for an AGN torus and a star-forming galaxy. This enables us to recover the emission from the AGN torus including the low-luminosity end, down to , which typically has significant host galaxy contamination. The sample demonstrates that the luminosity contribution of the AGN to the 12 m, the MIR, and the total IR bands is an increasing function of the 14-150 keV luminosity. We also find that for the most extreme cases, the IR pure-AGN emission from the torus can extend up to 90 m. The total IR AGN luminosity obtained through the IR SED decomposition enables us to estimate the fraction of the sky obscured by dust, i.e., the dust covering factor. We demonstrate that the median dust covering factor is always smaller than the median X-ray obscuration fraction above an AGN bolometric luminosity of . Considering that the X-ray obscuration fraction is equivalent to the covering factor coming from both the dust and gas, this indicates that an additional neutral gas component, along with the dusty torus, is responsible for the absorption of X-ray emission.
Abstract
We revisit the dependence of the covering factor (CF) of dust torus on physical properties of active galactic nuclei (AGNs) by taking into account an AGN polar dust emission. The CF is ...converted from a ratio of infrared (IR) luminosity contributed from AGN dust torus (
) and AGN bolometric luminosity (
L
bol
), by assuming a nonlinear relation between luminosity ratio and intrinsic CF. We select 37,181 type 1 quasars at
z
< 0.7 from the Sloan Digital Sky Survey Data Release 16 quasar catalog. Their
L
bol
, black hole mass (
M
BH
), and Eddington ratio (
λ
Edd
) are derived by spectral fitting with
QSFit
. We conduct spectral energy distribution decomposition by using
X-CIGALE
with a clumpy torus and polar dust model to estimate
without being affected by the contribution of stellar and AGN polar dust to IR emission. For 5752 quasars whose physical quantities are securely determined, we perform a correlation analysis on CF and (i)
L
bol
, (ii)
M
BH
, and (iii)
λ
Edd
. As a result, anticorrelations for CF–
L
bol
, CF–
M
BH
, and CF–
λ
Edd
are confirmed. We find that incorporating the AGN polar dust emission makes those anticorrelations stronger compared to those without considering it. This indicates that polar dust wind probably driven by AGN radiative pressure is one of the key components to regulate obscuring material of AGNs.
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Asymmetric regioselective vinylogous aza-Morita-Baylis-Hillman reactions by organocatalysis were developed. The reactions of 3-vinylcyclopentenone with various aldimines in the ...presence of chiral pyrrolidinopyridine catalysts gave the γ-adducts in high regioselectivity and moderate enantioselectivity.
We present a uniform broadband X-ray (0.5-100.0 keV) spectral analysis of 12 Swift/Burst Alert Telescope selected Compton-thick ( ) active galactic nuclei (CTAGNs) observed with Suzaku. The Suzaku ...data of three objects are published here for the first time. We fit the Suzaku and Swift spectra with models utilizing an analytic reflection code and those utilizing the Monte-Carlo-based model from an AGN torus by Ikeda et al. The main results are as follows: (1) The estimated intrinsic luminosity of a CTAGN strongly depends on the model; applying Compton scattering to the transmitted component in an analytic model may largely overestimate the intrinsic luminosity at large column densities. (2) Unabsorbed reflection components are commonly observed, suggesting that the tori are clumpy. (3) Most of CTAGNs show small scattering fractions (<0.5%), implying a buried AGN nature. (4) Comparison with the results obtained for Compton-thin AGNs suggests that the properties of these CTAGNs can be understood as a smooth extension from Compton-thin AGNs with heavier obscuration; we find no evidence that the bulk of the population of hard-X-ray-selected CTAGNs are different from less obscured objects.
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