Crystal Structure of FePb 4 Sb 6 Se 14 and its Structural Relationship with FePb 3 Sb 4 Se 10

Single crystals of FePb 4 Sb 6 Se 14 , were obtained from solid‐state combination of high purity elemental powders at 873K for three days. Single crystal X‐ray structure determination revealed that the compound crystallizes in the monoclinic space group P 2 1 / c (no. 14) and adopts the structure of Jamesonite (FePb 4 Sb 6 S 14 ). The structure contains two crystallographically independent lead atoms with monocapped and bicapped trigonal prismatic coordinations, three antimony atoms located in a distorted octahedral environment and one iron atom occupying a flattened octahedral coordination. Neighboring monocapped and bicapped trigonal prims around lead atoms share faces and edges to build a corrugated layer parallel to the ac plane. Octahedrally coordinated antimony atoms share edges to form one‐dimensional (1D) {SbSe} ∞ ribbons connecting adjacent corrugated layers. The distortion of the octahedral coordination around antimony atoms within the {SbSe} ∞ ribbons with the longest bond pointing towards the center of the ribbon, suggests the stereochemical activity of antimony lone‐pairs with their electron clouds pointing towards the center of the {SbSe} ∞ ribbon. The three dimensional framework resulting from the connectivity between the corrugated layers and the {SbSe} ∞ ribbons, contains isolated cylindrical voids parallel to [100] which are filled by a 1D Fe n Se 4n+2 straight chain of edge‐sharing FeSe 6 octahedra. The crystal structure of FePb 4 Sb 6 Se 14 is closely related to that of FePb 3 Sb 4 Se 10 as they are formed by similar building units with different sizes.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95198/1/2549_ftp.pd

The I-mode confinement regime at ASDEX Upgrade: global propert ies and characterization of strongly intermittent density fluctuations

Properties of the I­mode confinement regime on the ASDEX Upgrade tokamak are summarized. A weak dependence of the power threshold for the L­I transition on the toroidal magnetic field strength is found. During improved confinement, the edge radial electric field well deepens. Stability calculations show that the I­mode pedestal is peeling­ballooning stable. Turbulence investigations reveal strongly intermittent density fluctuations linked to the weakly coherent mode in the confined plasma, which become stronger as the confinement quality increases. Across all investigated structure sizes ( ≈ ⊥ k 5 – 12 cm − 1 , with ⊥ k the perpendicular wavenumber of turbulent density fluctuations), the intermittent turbulence bursts are observed. Comparison with bolometry data shows that they move poloidally toward the X­point and finally end up in the divertor. This might be indicative that they play a role in inhibiting the density profile growth, such that no pedestal is formed in the edge density profile.European Union (EUROfusion 633053)European Union (EUROfusion AWP15­ENR­09/IPP­02

Characterising The Atmospheric Dynamics Of HD209458b-like Hot Jupiters Using AI Driven Image Recognition/Categorisation

In-order to understand the results of recent observations of exoplanets, models have become increasingly complex. Unfortunately this increases both the computational cost and output size of said models. We intend to explore if AI-image-recognition can alleviate this burden. We used DYNAMICO to run a series of HD209458-like models with different orbital-radii. Training data for a number of features of interest was selected from the initial outputs of these models. This was used to train a pair of multi-categorisation convolutional-neural-networks (CNN), which we applied to our outer-atmosphere-equilibrated models. The features detected by our CNNs revealed that our models fall into two regimes: models with a shorter orbital-radii exhibit significant global mixing which shapes the entire atmospheres dynamics. Whereas, models with longer orbital-radii exhibit negligible mixing except at mid-pressures. Here, the initial non-detection of any trained features revealed a surprise: a night-side hot-spot. Analysis suggests that this occurs when rotational influence is sufficiently weak that divergent flows from the day-side to the night-side dominate over rotational-driven transport, such as the equatorial jet. We suggest that image-classification may play an important role in future, computational, atmospheric studies. However special care must be paid to the data feed into the model, from the colourmap, to training the CNN on features with enough breadth and complexity that the CNN can learn to detect them. However, by using preliminary-studies and prior-models, this should be more than achievable for future exascale calculations, allowing for a significant reduction in future workloads and computational resources.Comment: Accepted for publication in Ap

1H and 13C NMR assignments for a series of Diels–Alder adducts of anthracene and 9‐substituted anthracenes

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/111949/1/mrc4268.pd