Terpyridine Functionalized Dye-Doped Silica Nanoparticles (DDSN) for Detection of Metal Ions

In an effort to synthesize a novel silica nanoparticle platform for the fluorescent sensing of metal ions and future use in QDA, we synthesized from the bottom up a novel 2, 2’: 2’, 6- terpyridine functionalized fluorescein doped silica nanoparticle system capable of the sensitive detection of Cu2+ and Co2+. To further probe the properties of our nanoparticle system, we substitute the fluorescein dye of rhodamine and have observed differences in the selectivity and sensitivity of the system indicative of the potential customizability of the system. Initial QDA results on the fluorescein system suggest that while the signal is returned upon the introduction of EDTA, L-histidine, and epinephrine, the fluorescein dye in our system may interact with many of the anions tested

Revealing the binary origin of Type Ic superluminous supernovae through nebular hydrogen emission

We propose that nebular H-alpha emission as detected in the Type Ic superluminous supernova iPTF13ehe stems from matter which is stripped from a companion star when the supernova ejecta collide with it. The temporal evolution, the line broadening, and the overall blueshift of the emission are consistent with this interpretation. We scale the nebular H-alpha luminosity predicted for Type Ia supernovae in single-degenerate systems to derive the stripped mass required to explain the H-alpha luminosity of iPTF13ehe. We find a stripped mass of 0.1 - 0.9 solar masses, assuming that the supernova luminosity is powered by radioactivity or magnetar spin down. Because a central heating source is required to excite the H-alpha emission, an interaction-powered model is not favored for iPTF13ehe if the H-alpha emission is from stripped matter. We derive a companion mass of more than 20 solar masses and a binary separation of less than about 20 companion radii based on the stripping efficiency during the collision, indicating that the supernova progenitor and the companion formed a massive close binary system. If Type Ic superluminous supernovae generally occur in massive close binary systems, the early brightening observed previously in several Type Ic superluminous supernovae may also be due to the collision with a close companion. Observations of nebular hydrogen emission in future Type Ic superluminous supernovae will enable us to test this interpretation.Comment: 4 pages, 1 figure, 1 table, accepted by Astronomy & Astrophysics Letter

Saddle Points and Dynamics of Lennard-Jones Clusters, Solids and Supercooled Liquids

The properties of higher-index saddle points have been invoked in recent theories of the dynamics of supercooled liquids. Here we examine in detail a mapping of configurations to saddle points using minimization of $|\nabla E|^2$, which has been used in previous work to support these theories. The examples we consider are a two-dimensional model energy surface and binary Lennard-Jones liquids and solids. A shortcoming of the mapping is its failure to divide the potential energy surface into basins of attraction surrounding saddle points, because there are many minima of $|\nabla E|^2$ that do not correspond to stationary points of the potential energy. In fact, most liquid configurations are mapped to such points for the system we consider. We therefore develop an alternative route to investigate higher-index saddle points and obtain near complete distributions of saddles for small Lennard-Jones clusters. The distribution of the number of stationary points as a function of the index is found to be Gaussian, and the average energy increases linearly with saddle point index in agreement with previous results for bulk systems.Comment: 14 pages, 7 figure

Helical topological superconductivity in intrinsic quantum Hall superconductors

One of the approaches to engineering topological superconductivity in a two dimensional electron gas with spin-orbit coupling is to proximity-couple it to an s-wave type-II superconductor with a non-standard Abrikosov flux lattice that is neither triangular or square but has an even number of superconducting flux quanta per unit cell. Here we ask whether exposing an intrinsic two-dimensional superconductor with spin orbit coupling to a perpendicular magnetic field -- an intrinsic quantum Hall superconductor -- can give rise to topological superconductivity. We investigate this question in a mean-field theory and obtain, in a self-consistent fashion, the real space configuration of the superconducting order parameter, which encodes information about the topology of the superconductivity as well as the nature of the Abrikosov lattice. We find small regions of topological superconductivity in the parameter space, which can be greatly enlarged by the addition of a superlattice potential. Topological superconductivity is seen to be correlated with the presence of either a distorted Abrikosov lattice or an Abrikosov lattice of giant vortices which carry two superconducting flux quanta. To identify the lowest energy solution, it is essential to employ helical order parameters. Finally, we discuss the experimental feasibility of this proposal

The gold standard: accurate stellar and planetary parameters for eight Kepler M dwarf systems enabled by parallaxes

We report parallaxes and proper motions from the Hawaii Infrared Parallax Program for eight nearby M dwarf stars with transiting exoplanets discovered by Kepler. We combine our directly measured distances with mass-luminosity and radius–luminosity relationships to significantly improve constraints on the host stars’ properties. Our astrometry enables the identification of wide stellar companions to the planet hosts. Within our limited sample, all the multi-transiting planet hosts (three of three) appear to be single stars, while nearly all (four of five) of the systems with a single detected planet have wide stellar companions. By applying strict priors on average stellar density from our updated radius and mass in our transit fitting analysis, we measure the eccentricity probability distributions for each transiting planet. Planets in single-star systems tend to have smaller eccentricities than those in binaries, although this difference is not significant in our small sample. In the case of Kepler-42bcd, where the eccentricities are known to be ≃0, we demonstrate that such systems can serve as powerful tests of M dwarf evolutionary models by working in L⋆ − ρ⋆ space. The transit-fit density for Kepler- 42bcd is inconsistent with model predictions at 2.1σ (22%), but matches more empirical estimates at 0.2σ (2%), consistent with earlier results showing model radii of M dwarfs are underinflated. Gaia will provide high-precision parallaxes for the entire Kepler M dwarf sample, and TESS will identify more planets transiting nearby, late-type stars, enabling significant improvements in our understanding of the eccentricity distribution of small planets and the parameters of late-type dwarfs.Support for Program number HST-HF2-51364.001-A was provided by NASA through a grant from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Incorporated, under NASA contract NAS5-26555.Some of the data presented in this paper were obtained from the Mikulski Archive for Space Telescopes (MAST). STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. Support for MAST for non-HST data is provided by the NASA Office of Space Science via grant NNX09AF08G and by other grants and contracts. This paper includes data collected by the Kepler mission. Funding for the Kepler mission is provided by the NASA Science Mission directorate. The authors acknowledge the Texas Advanced Computing Center (TACC) at The University of Texas at Austin for providing HPC resources that have contributed to the research results reported within this paper. URL: http://www.tacc.utexas.edu. (HST-HF2-51364.001-A - NASA through Space Telescope Science Institute; NAS5-26555 - NASA; NNX09AF08G - NASA Office of Space Science; NASA Science Mission directorate

Maternal obesity has little effect on the immediate offspring but impacts on the next generation

Maternal obesity during pregnancy has been linked to an increased risk of obesity and cardiometabolic disease in the offspring, a phenomenon attributed to developmental programming. Programming effects may be transmissible across generations through both maternal and paternal inheritance, although the mechanisms remain unclear. Using a mouse model, we explored the effects of moderate maternal diet-induced obesity (DIO) on weight gain and glucose-insulin homeostasis in first-generation (F1) and second-generation offspring. DIO was associated with insulin resistance, hyperglycemia and dyslipidemia before pregnancy. Birth weight was reduced in female offspring of DIO mothers (by 6%, P = .039), and DIO offspring were heavier than controls at weaning (males by 47%, females by 27%), however there were no differences in glucose tolerance, plasma lipids, or hepatic gene expression at 6 months. Despite the relative lack of effects in the F1, we found clear fetal growth restriction and persistent metabolic changes in otherwise unmanipulated second-generation offspring with effects on birth weight, insulin levels, and hepatic gene expression that were transmitted through both maternal and paternal lines. This suggests that the consequences of the current dietary obesity epidemic may also have an impact on the descendants of obese individuals, even when the phenotype of the F1 appears largely unaffected

Mapping results for a set of cGAL effectors and drivers

Recently, the GAL4-UAS system (cGAL) has been adapted for use in C. elegans for control of gene expression across 15°C - 25°C (Wang et al., 2017). In order to create a desired gene expression pattern, one crosses a transgenic strain containing a driver construct with another strain containing an effector gene. Here we mapped several cGAL driver and effector integrations. We first crossed each of the cGAL driver and effector strains with N2 males, picked the heterozygous male progeny, crossed them with hermaphrodites of the mapping strain (DA438), picked L4 hermaphrodites with the corresponding transgenic marker of the driver or effector strain and scored the progeny in the next generation. The DA438 strain contains six recessive mutations, each of which locates on one of the six chromosomes and produces visible phenotypes (Bli on chromosome I, Rol on II, Vab on III, Unc on IV, Dpy on V, and Lon on X (Avery, 1993). F2 progeny with each of the six phenotypes were selected and examined for the presence or absence of the dominant marker associated with the transgene. In the cases where the dominant transgene marker is unlinked to the recessive phenotypic marker, about three quarters of the F2 progeny will have the dominant marker. If the two markers are linked, very few or no animals are expected to have the dominant transgenic marker. The following tables summarize the mapping results for each cGAL strain, stating the ratios of the F2 mutant progeny with and without the dominant transgenic marker