1,062 research outputs found
Intrinsic Spin Hall Conductivity of MoTe2 and WTe2 Semimetals
We report a comprehensive study on the intrinsic spin Hall conductivity (SHC)
of semimetals MoTe2 and WTe2 by ab initio calculation. Large SHC and desirable
spin Hall angles have been discovered, due to the strong spin orbit coupling
effect and low charge conductivity in semimetals. Diverse anisotropic SHC
values, attributed to the unusual reduced-symmetry crystalline structure, have
been revealed. We report an effective method on SHC optimization by electron
doping, and exhibit the mechanism of SHC variation respect to the energy
shifting by the spin Berry curvature. Our work provides insights into the
realization of strong spin Hall effects in 2D systems
The Unusual AGN Host NGC 1266: Evidence for Shocks in a Molecular Gas Rich S0 Galaxy with a Low Luminosity Nucleus
NGC 1266 is a lenticular galaxy (S0) hosting an active galactic nucleus
(AGN), and known to contain a large amount of shocked gas. We compare the
luminosity ratio of mid-\emph{J} CO lines to IR continuum with star-forming
galaxies (SFGs), and then model the CO spectral line energy distribution
(SLED). We confirm that in the mid- and high-\emph{J} regions ( =
4--13), the C-type shock ( = 25 km s, =
cm) can reproduce the CO observations well. The galaxy
spectral energy distribution (SED) is constructed and modeled by the code {\tt
X-CIGALE} and obtains a set of physical parameters including the star formation
rate (SFR, 1.17 0.47 \emph{M}yr). Also, our work
provides SFR derivation of [C\,{\sc ii}] from the neutral hydrogen regions only
(1.38 0.14 yr). Previous studies have illusive
conclusions on the AGN or starburst nature of the NGC 1266 nucleus. Our SED
model shows that the hidden AGN in the system is intrinsically low-luminosity,
consequently the infrared luminosity of the AGN does not reach the expected
level. Archival data from \emph{NuSTAR} hard X-ray observations in the 3--79
keV band shows a marginal detection, disfavoring presence of an obscured
luminous AGN and implying that a compact starburst is more likely dominant for
the NGC 1266 nucleus
Characterization of the Biosynthetic Gene Cluster for Benzoxazole Antibiotics A33853 Reveals Unusual Assembly Logic
SummaryA33853, which shows excellent bioactivity against Leishmania, is a benzoxazole-family compound formed from two moieties of 3-hydroxyanthranilic acid and one 3-hydroxypicolinic acid. In this study, we have identified the gene cluster responsible for the biosynthesis of A33853 in Streptomyces sp. NRRL12068 through genome mining and heterologous expression. Bioinformatics analysis and functional characterization of the orfs contained in the gene cluster revealed that the biosynthesis of A33853 is directed by a group of unusual enzymes. In particular, BomK, annotated as a ketosynthase, was found to catalyze the amide bond formation between 3-hydroxypicolinic and 3-hydroxyanthranilic acid during the assembly of A33853. BomJ, a putative ATP-dependent coenzyme A ligase, and BomN, a putative amidohydrolase, were further proposed to be involved in the benzoxazole formation in A33853 according to gene deletion experiments. Finally, we have successfully utilized mutasynthesis to generate two analogs of A33853, which were reported previously to possess excellent anti-leishmanial activity
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