EPR and pulsed ENDOR study of intermediates from reactions of aromatic azides with group 13 metal trichlorides

The reactions of group 13 metal trichlorides with aromatic azides were examined by CW EPR and pulsed ENDOR spectroscopies. Complex EPR spectra were obtained from reactions of aluminium, gallium and indium trichlorides with phenyl azides containing a variety of substituents. Analysis of the spectra showed that 4-methoxy-, 3-methoxy- and 2-methoxyphenyl azides all gave ‘dimer’ radical cations [ArNHC6H4NH2]+• and trimers [ArNHC6H4NHC6H4NH2]+• followed by polymers. 4-Azidobenzonitrile, with its electron-withdrawing substituent, did not react. In general the aromatic azides appeared to react most rapidly with AlCl3 but this reagent tended to generate much polymer. InCl3 was the least reactive group 13 halide. DFT computations of the radical cations provided corroborating evidence and suggested that the unpaired electrons were accommodated in extensive π-delocalised orbitals. A mechanism to account for the reductive conversion of aromatic azides to the corresponding anilines and thence to the dimers and trimers is proposedPublisher PDFPeer reviewe

Granular circulation in a cylindrical pan: simulations of reversing radial and tangential flows

Granular flows due to simultaneous vertical and horizontal excitations of a flat-bottomed cylindrical pan are investigated using event-driven molecular dynamics simulations. In agreement with recent experimental results, we observe a transition from a solid-like state, to a fluidized state in which circulatory flow occurs simultaneously in the radial and tangential directions. By going beyond the range of conditions explored experimentally, we find that each of these circulations reverse their direction as a function of the control parameters of the motion. We numerically evaluate the dynamical phase diagram for this system and show, using a simple model, that the solid-fluid transition can be understood in terms of a critical value of the radial acceleration of the pan bottom; and that the circulation reversals are controlled by the phase shift relating the horizontal and vertical components of the vibrations. We also discuss the crucial role played by the geometry of the boundary conditions, and point out a relationship of the circulation observed here and the flows generated in vibratory conveyors.Comment: 10 pages, 8 figure

One dimensional drift-diffusion between two absorbing boundaries: application to granular segregation

Motivated by a novel method for granular segregation, we analyze the one dimensional drift-diffusion between two absorbing boundaries. The time evolution of the probability distribution and the rate of absorption are given by explicit formulae, the splitting probability and the mean first passage time are also calculated. Applying the results we find optimal parameters for segregating binary granular mixtures.Comment: RevTeX, 5 pages, 6 figure

NuSTAR Observations of the Black Hole GS 1354-645: Evidence of Rapid Black Hole Spin

We present the results of a NuSTAR study of the dynamically confirmed stellar-mass black hole GS 1354-645. The source was observed during its 2015 "hard" state outburst; we concentrate on spectra from two relatively bright phases. In the higher-flux observation, the broadband NuSTAR spectra reveal a clear, strong disk reflection spectrum, blurred by a degree that requires a black hole spin of a = cJ/GM^2 > 0.98 (1 sigma statistical limits only). The fits also require a high inclination: theta = 75(2) degrees. Strong "dips" are sometimes observed in the X-ray light curves of sources viewed at such an angle; these are absent, perhaps indicating that dips correspond to flared disk structures that only manifest at higher accretion rates. In the lower-flux observation, there is evidence of radial truncation of the thin accretion disk. We discuss these results in the context of spin in stellar-mass black holes, and inner accretion flow geometries at moderate accretion rates.Comment: Accepted for publication in ApJ Letter

Stress Distribution in Porcelain-Fused-to-Gold Crowns and Preparations Constructed with Photoelastic Plastics

Composite models representing porcelain-fused-to-gold restorations were constructed from photoelastic plastics. Better stress distributions resulted when the porcelain-gold joint was as far as feasible from the loading site, a bulk of gold was present on the lingual shoulder, and the porcelain-gold joint at the shoulder was 30° from the horizontal.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66999/2/10.1177_00220345710500053101.pd

Innovative package for frontline maternal, newborn and child health workers in South Sudan

Improving maternal, newborn, and child health is a leading priority worldwide. It is a particularly urgent issue in South Sudan, which suffers from the world’s worst maternal mortality and among the worst newborn and child mortalities. A leading barrier to improving these health indices is limited frontline health worker capacity. In partnership with the Ministry of Health, the Division of Global Health and Human Rights (Department of Emergency Medicine, Massachusetts General Hospital, Boston, USA) has developed and is currently implementing its novel Maternal, Newborn, and Child Survival (MNCS) Initiative throughout much of South Sudan. The purpose of MNCS is to build frontline health worker capacity through a training package that includes:1. A participatory training course2. Pictorial checklists to guide prevention, care, and referral3. Re-useable medical equipment and commodities.Program implementation began in November 2010 utilizing a training-of-trainers model. To date, 72 local trainers and 632 frontline health workers have completed the training and received their MNCS checklists and commodities. Initial monitoring and evaluation results are encouraging as further evaluation continues. This innovative training package may also serve as a model for building capacity for maternal, newborn, and child health in other resource limited settings beyond South Sudan

The Ethics of Choice in Single-Player Video Games

Video games are a specific kind of virtual world which many engage with on a daily basis; as such, we cannot ignore the values they embody. In this paper I argue that it is possible to cause moral harm or benefit within a video game, specifically by drawing attention to the nature of the choices both players and designers make. I discuss ways in which games attempt to represent morality, arguing that while flawed, even games with seemingly superficial devices such as morality meters can attempt to promote moral reflection. Ultimately, I argue that the moral status of the actions depends on the effects of those actions on the player herself; if those actions make us less ethical then the actions are wrong. Unfortunately, it is not clear to me that players are always in a position to tell whether this is the case

Accreting Black Holes

This chapter provides a general overview of the theory and observations of black holes in the Universe and on their interpretation. We briefly review the black hole classes, accretion disk models, spectral state classification, the AGN classification, and the leading techniques for measuring black hole spins. We also introduce quasi-periodic oscillations, the shadow of black holes, and the observations and the theoretical models of jets.Comment: 41 pages, 18 figures. To appear in "Tutorial Guide to X-ray and Gamma-ray Astronomy: Data Reduction and Analysis" (Ed. C. Bambi, Springer Singapore, 2020). v3: fixed some typos and updated some parts. arXiv admin note: substantial text overlap with arXiv:1711.1025