Observation of Hysteretic Transport Due to Dynamic Nuclear Spin Polarization in a GaAs Lateral Double Quantum Dot

We report a new transport feature in a GaAs lateral double quantum dot that emerges only for magnetic field sweeps and shows hysteresis due to dynamic nuclear spin polarization (DNP). This DNP signal appears in the Coulomb blockade regime by virtue of the finite inter-dot tunnel coupling and originates from the crossing between ground levels of the spin triplet and singlet extensively used for nuclear spin manipulations in pulsed gate experiments. The unexpectedly large signal intensity is suggestive of unbalanced DNP between the two dots, which opens up the possibility of controlling electron and nuclear spin states via DC transport.Comment: 5 pages, 4 figure

Near-Infrared Extinction in The Coalsack Globule 2

We have conducted J, H, and Ks imaging observations for the Coalsack Globule 2 with the SIRIUS infrared camera on the IRSF 1.4 m telescope at SAAO, and determined the color excess ratio, E(J-H)/E(H-Ks). The ratio is determined in the same photometric system as our previous study for the rho Oph and Cha clouds without any color transformation; this enables us to directly compare the near-infrared extinction laws among these regions. The current ratio E(J-H)/E(H-Ks) = 1.91 +- 0.01 for the extinction range 0.5 < E(J-H) <1.8 is significantly larger than the ratios for the rho Oph and Cha clouds (E(J-H)/E(H-Ks) = 1.60-1.69). This ratio corresponds to a large negative index alpha = 2.34 +- 0.01 when the wavelength dependence of extinction is approximated by a power law which might indicate little growth of dust grains, or larger abundance of dielectric non-absorbing components such as silicates, or both in this cloud. We also confirm that the color excess ratio for the Coalsack Globule 2 has a trend of increasing with decreasing optical depth, which is the same trend as the rho Oph and Cha clouds have.Comment: 13 pages, 5 figures, and 2 tables, Ap

Mechanochemical Synthesis of Dispersible Platinum Nanosheets for Enhanced Catalysis in a Microreactor

Nanosheet fabrication usually requires some self-assembly process of the ingredients themselves or self-assembled templates to lead to the local anisotropy. Macroscopic forces and dynamics cannot usually generate the local anisotropy to synthesize nanosheets in a solution because the anisotropies of the macroscopic mechanical forces and dynamics are promptly relaxed in the molecular scale in a liquid phase. Here, we report the mechanochemical synthesis of dispersible platinum nanosheets (PtNSs) using a microreactor. This work is the first example of bottom-up nanosheet synthesis of a nonexfoliable compound in a microflow reactor. The nanosheets grow through the lateral fusion of nanoplatelets in the hydrophilic space of the stable hyperswollen lyotropic lamellar (HL) phase of a surfactant solution. The lateral fusion is accelerated as the flow rate increases because the area of the bilayer in the HL phase increases with shear stress. The mechanical energy to promote the growth of the PtNSs can also be extracted in different ways. Most simply, syringe pumps electrically generate it. We also illustrate mechanochemical synthesis using gravity, the most universal and eco-friendly energy source on the earth. It is also the first example of the fabrication of anisotropic nanoparticles using gravity. Larger PtNSs show higher catalytic activity for the reduction reaction from 4-nitrophenol to 4-aminophenol due to their dispersibility; surprisingly, the exponential increase of the fusion patterns of nanoplatelets dramatically reduces the agglomeration of PtNSs. These PtNSs perform better in catalysis and should be promising for hydrogen production, fuel cells, and sensors because of their large surface area and dispersibility. This method could open up a pathway to valuable nanosheets.Koki Sasaki, Koji Miyake, Yoshiaki Uchida et al. Mechanochemical Synthesis of Dispersible Platinum Nanosheets for Enhanced Catalysis in a Microreactor. ACS Applied Nano Materials, 5 (4), 4998-5005, April 22, © 2022 American Chemical Society. https://doi.org/10.1021/acsanm.1c0458

Local Lunar Gravity Field Analysis over the South Pole-aitken Basin from SELENE Farside Tracking Data

We present a method with which we determined the local lunar gravity field model over the South Pole-Aitken (SPA) basin on the farside of the Moon by estimating adjustments to a global lunar gravity field model using SELENE tracking data. Our adjustments are expressed in localized functions concentrated over the SPA region in a spherical cap with a radius of 45deg centered at (191.1 deg E, 53.2 deg S), and the resolution is equivalent to a 150th degree and order spherical harmonics expansion. The new solution over SPA was used in several applications of geophysical analysis. It shows an increased correlation with high-resolution lunar topography in the frequency band l = 40-70, and admittance values are slightly different and more leveled when compared to other, global gravity field models using the same data. The adjustments expressed in free-air anomalies and differences in Bouguer anomalies between the local solution and the a priori global solution correlate with topographic surface features. The Moho structure beneath the SPA basin is slightly modified in our solution, most notably at the southern rim of the Apollo basin and around the Zeeman crate