Total Solar Eclipse: August 21, 2017

Bottom-up fabrication using DNA is a promising approach for the creation of nanoarchitectures. Accordingly, nanomaterials with specific electronic, photonic, or other functions are precisely and programmably positioned on DNA nanostructures from a disordered collection of smaller parts. These self-assembled structures offer significant potential in many domains such as sensing, drug delivery, and electronic device manufacturing. This review describes recent progress in organizing nanoscale morphologies of metals, semiconductors, and carbon nanotubes using DNA templates. We describe common substrates, DNA templates, seeding, plating, nanomaterial placement, and methods for structural and electrical characterization. Finally, our outlook for DNA-enabled bottom-up nanofabrication of materials is presented.

Holographic reconstructions of the sound field in the vicinity of a tied-down F-35 aircraft were achieved by applying multisource statistically optimized near-field acoustical holography to measurements taken at a linear ground array approximately parallel to the shear layer of the jet. The measured field, as well as reconstructions to locations where the field was not measured, show that the field can be described as a superposition of multiple lobes in the spatiospectral domain. These lobes are observed in the field when the aircraft is operated at a variety of engine powers, including afterburner. For a given engine power, as frequency is increased, the spatial lobes in the mixing-noise region shift aft in directivity until they disappear beyond the aperture of the measurement while new ones appear toward the sideline and shift aft with the others. At a fixed frequency, when engine power is increased, the forward-most spatial lobe increases in level more than the other lobes, which is a major factor in the observed forward shift in overall directivity with increasing engine power. Frequency-dependent raytracing of the spatial lobes gives insight into the directivity and apparent source locations for jet noise components as a function of frequency and engine power.

We conduct spectral observations of 138 superthin galaxies (STGs) with high radial-to-vertical stellar disk scale ratios with the Dual Imaging Spectrograph on the 3.5 m telescope at the Apache Point Observatory (APO) to obtain the ionized gas rotation curves with R ∼5000 resolution. We also performed near-infrared (NIR) H and Ks photometry for 18 galaxies with the NICFPS camera on the 3.5 m telescope. The spectra, the NIR photometry, and published optical and NIR photometry are used for modeling that utilizes the thickness of the stellar disk and rotation curves simultaneously. The projection and dust extinction effects are taken into account. We evaluate eight models that differ in their free parameters and constraints. As a result, we estimated the masses and scale lengths of the galactic dark halos. We find systematic differences between the properties of our red and blue STGs. The blue STGs have a large fraction of dynamically underevolved galaxies whose vertical velocity dispersion is low in both gas and stellar disks. The dark halo-to-disk scale ratio is shorter in the red STGs than in the blue ones, but in a majority of all STGs, this ratio is under 2. The optical color (r − i) of the STGs correlates with their rotation curve maximum, vertical velocity dispersion in stellar disks, and mass of the dark halo. We conclude that there is a threshold central surface density of 50 M ⊙ pc−2 below which we do not observe very thin, rotationally supported galactic disks.