7,421 research outputs found
Dynamic origin of chirality transfer between chiral surface and achiral ligand in Au38 clusters
The transfer of chirality between nanomolecules is at the core of several applications in chiral technology such as sensing and catalysis. However, the origin of this phenomenon and how exactly nanoscale objects transfer chirality to molecules in their vicinity remain largely obscure. Here, we show that the transfer of chirality for the intrinsically chiral gold cluster Au38(SR)24 is site dependent; that is, it differs depending on the ligand-binding sites. This is closely related to the dynamic nature of the ligands on the cluster surface. Using a combination of NMR techniques and molecular dynamics simulations, we could assign the four symmetry- unique ligands on the cluster. The study reveals largely different conformational dynamics of the bound ligands, explaining the diverse diastereotopicities observed for the CH2 protons of the ligands. Although chirality is a structural property, our study reveals the importance of dynamics for the transfer of chirality
Bosentan regulates the expression of adhesion molecules on circulating T cells and serum soluble adhesion molecules in systemic sclerosis-associated pulmonary arterial hypertension
31 Rescue of deltaF508 CFTR in CFBE41o- cells is dependent on actin cytoskeleton interaction with ezrin and NHERF1
Magellan Adaptive Optics first-light observations of the exoplanet beta Pic b. II. 3-5 micron direct imaging with MagAO+Clio, and the empirical bolometric luminosity of a self-luminous giant planet
Young giant exoplanets are a unique laboratory for understanding cool,
low-gravity atmospheres. A quintessential example is the massive extrasolar
planet Pic b, which is 9 AU from and embedded in the debris disk of the
young nearby A6V star Pictoris. We observed the system with first light
of the Magellan Adaptive Optics (MagAO) system. In Paper I we presented the
first CCD detection of this planet with MagAO+VisAO. Here we present four
MagAO+Clio images of Pic b at 3.1 m, 3.3 m, , and
, including the first observation in the fundamental CH band. To
remove systematic errors from the spectral energy distribution (SED), we
re-calibrate the literature photometry and combine it with our own data, for a
total of 22 independent measurements at 16 passbands from 0.99--4.8 m.
Atmosphere models demonstrate the planet is cloudy but are degenerate in
effective temperature and radius. The measured SED now covers 80\% of the
planet's energy, so we approach the bolometric luminosity empirically. We
calculate the luminosity by extending the measured SED with a blackbody and
integrating to find log(/) . From our
bolometric luminosity and an age of 233 Myr, hot-start evolutionary tracks
give a mass of 12.70.3 , radius of 1.450.02 , and
of 170823 K (model-dependent errors not included). Our
empirically-determined luminosity is in agreement with values from atmospheric
models (typically dex), but brighter than values from the field-dwarf
bolometric correction (typically dex), illustrating the limitations in
comparing young exoplanets to old brown dwarfs.Comment: Accepted to ApJ. 27 pages, 22 figures, 19 table
Ultrasensitive Photoresponse of Graphene Quantum Dot in the Coulomb Blockade Regime to THz Radiation
Graphene quantum dots (GQDs) have recently attracted considerable attention,
with appealing properties for terahertz (THz) technology. This includes the
demonstration of large thermal bolometric effects in GQDs when illuminated by
THz radiation. However, the interaction of THz photons with GQDs in the Coulomb
blockade regime - single electron transport regime - remains unexplored. Here,
we demonstrate the ultrasensitive photoresponse to THz radiation (from <0.1 to
10 THz) of a hBN-encapsulated GQD in the Coulomb blockade regime at low
temperature (170 mK). We show that THz radiation of 10 pW provides a
photocurrent response in the nanoampere range, resulting from a renormalization
of the chemical potential of the GQD of 0.15 meV. We attribute this
photoresponse to an interfacial photogating effect. Furthermore, our analysis
reveals the absence of thermal effects, opening new directions in the study of
coherent quantum effects at THz frequencies in GQDs
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