White Paper for Enabling and Reusing Multilingual Citizen Contributions in the Archival Record

National Endowment for the Humanities Grant HAA-269051-20UT Librarie

An ALMA survey of DCN/H13^{13}CN and DCO+^+/H13^{13}CO+^+ in protoplanetary disks

The deuterium enrichment of molecules is sensitive to their formation environment. Constraining patterns of deuterium chemistry in protoplanetary disks is therefore useful for probing how material is inherited or reprocessed throughout the stages of star and planet formation. We present ALMA observations at $\sim0.6"$ resolution of DCO$^+$, H$^{13}$CO$^+$, DCN, and H$^{13}$CN in the full disks around T Tauri stars AS 209 and IM Lup, the transition disks around T Tauri stars V4046 Sgr and LkCa 15, and the full disks around Herbig Ae stars MWC 480 and HD 163296. We also present ALMA observations of HCN in the IM Lup disk. DCN, DCO$^+$, and H$^{13}$CO$^+$ are detected in all disks, and H$^{13}$CN in all but the IM Lup disk. We find efficient deuterium fractionation for the sample, with estimates of disk-averaged DCO$^+$/HCO$^+$ and DCN/HCN abundance ratios ranging from $\sim0.02-0.06$ and $\sim0.005-0.08$, respectively, which is comparable to values reported for other ISM environments. The relative distributions of DCN and DCO$^+$ vary between disks, suggesting that multiple formation pathways may be needed to explain the diverse emission morphologies. In addition, gaps and rings observed in both H$^{13}$CO$^+$ and DCO$^+$ emission provide new evidence that DCO$^+$ bears a complex relationship with the location of the midplane CO snowline.Comment: 36 pages, 14 figures, updated to match figure order of published version in Ap

Carbonium vs. carbenium ion-like transition state geometries for carbocation cyclization – how strain associated with bridging affects 5-exo vs. 6-endo selectivity

Quantum chemical calculations are used to explore the origins of regioselectivity for proton-, Pt(II)- and Pd(II)-promoted cyclizations of 1,5-hexadienes, 5-aminoalkenes, and allylic acetimidates. The strain associated with achieving carbonium ion-like transition state geometries is shown to be a key factor in controlling 5-exo vs. 6-endo selectivity

Design Optimization of DR3AM Vapor Polishing Device for ABS 3D-Printed Parts

3D printing is an additive manufacturing method that turns digital design into an actual product. A 3D-printed part sometimes requires post-processing to enhance its physical and mechanical properties. Acetone vapor polishing is one of those techniques which is highly beneficial in smoothing ABS 3D-printed parts. Previously, an acetone vapor polishing device has been developed which uses a mist maker. However, for a more efficient polishing method, an optimized vapor polishing device using heat has been fabricated in this study. To assess the efficiency of this device, the researchers test the dimensional accuracy, surface roughness, tensile strength, and impact strength of polished and unpolished ABS 3D-printed specimens. The findings showed that the surface smoothness of the polished cube specimens did not significantly alter its physical geometry. The tensile test reveals that the overall elasticity of the polished tensile specimen has increased significantly while the impact test also shows that the polished specimens have the capacity to sustain a resistive impact from a swinging pendulum. Thus, all testing procedures indicated that post-processing using the optimized vapor polishing device has improved the overall physical and mechanical properties of the polished specimens

Properties of a thin accretion disk around a rotating non-Kerr black hole

We study the accretion process in the thin disk around a rotating non-Kerr black hole with a deformed parameter and an unbound rotation parameter. Our results show that the presence of the deformed parameter $\epsilon$ modifies the standard properties of the disk. For the case in which the black hole is more oblate than a Kerr black hole, the larger deviation leads to the smaller energy flux, the lower radiation temperature and the fainter spectra luminosity in the disk. For the black hole with positive deformed parameter, we find that the effect of the deformed parameter on the disk becomes more complicated. It depends not only on the rotation direction of the black hole and the orbit particles, but also on the sign of the difference between the deformed parameter $\epsilon$ and a certain critical value $\epsilon_{c}$. These significant features in the mass accretion process may provide a possibility to test the no-hair theorem in the strong field regime in future astronomical observations.Comment: 13 pages, 5 figures. References added, Expanded discussion of the marginally stable orbit and its consequence. Accepted for publication in Phys. Lett.