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The present work describes a density-functional theory (DFT) study of TlReO 4 in combination with powder x-ray diffraction experiments as a function of temperature and Raman measurements at ambient temperature. X-ray diffraction measurements reveal three different structures as a function of temperature. A monoclinic structure (space group P2 1 /c) is observed at room temperature while two isostructural tetragonal structures (space group I4 1 /a) are found at low- and high-temperature. In order to complement the experimental results first-principles DFT calculations were performed to compute the structural energy differences. From the total energies it is evident that the monoclinic structure has the lowest total energy when compared to the orthorhombic structure, which was originally proposed to be the structure at room temperature, which agrees with our experiments. The structural and vibrational properties of the low- and room-temperature phase of TlReO 4 have been calculated using DFT. Inclusion of van der Waals correction to the standard DFT exchange correlation functional is found to improve the agreement with the observed structural and vibrational properties. The Born effective charge of these phases has also been studied which shows a combination of ionic and covalent nature, resembling metavalent bonding. Calculations of zone-center phonon frequencies lead to the symmetry assignment of previously reported low-temperature Raman modes. We have determined the frequencies of the eight infrared-active, 13 Raman-active and three silent modes of low-temperature TlReO 4 along with 105 infrared-active and 108 Raman-active modes for room-temperature TlReO 4 . Phonons of these two phases of TlReO 4 are mainly divided into three regions which are below 150 cm -1 due to vibration of whole crystal, 250 to 400 cm -1 due to wagging, scissoring, rocking and twisting and above 900 cm -1 due to stretching in ReO 4 tetrahedron. The strongest infrared peak is associated to the internal asymmetric stretching of ReO 4 whereas the strongest Raman peak is associated to the internal symmetric stretching of ReO 4 . We have also measured the room-temperature Raman spectra of monoclinic TlReO 4 identifying up to 28 modes. This Raman spectrum has been interpreted by comparison with the previously reported Raman frequencies of the low-temperature phase and our calculated Raman frequencies of low- and room-temperature phases of TlReO 4 .

The synthesis, structures and magnetism of six mixed 3d-5d oxides Ba3BM2O9 (B = Ti, Y, Zn; M = Ru, Os) are described. When prepared at ambient pressure the six oxides display a 6H type perovskite structure comprised of corner sharing BO6 and face sharing M2O9 motifs. Synchrotron X-ray diffraction reveals a small monoclinic distortion in Ba3ZnRu2O9; the remaining oxides exhibit a hexagonal structure. The magnetic properties are dominated by the M-M interactions across the shared face. Only in the mixed valent (M4+/M5+) Y oxides is evidence of long-range magnetic order found. Application of high pressure/high temperature synthetic methods for the Ru containing oxides changes the structure to the archetypical cubic Pm3[combining macron]m perovskite structure, where the B and Ru cations are disordered on the corner sharing BO6 octahedral sites. The magnetic properties of the cubic oxides are dominated by short range antiferromagnetic interactions, the chemical disorder inhibiting long range ordering.

Oxides of the form AB O 4 with A = K, Rb, Cs and B = Ru and Os have been synthesized and characterized by diffraction and magnetic techniques. For A = K the oxides adopted the tetragonal ( I 4 1 / a ) scheelite structure. RbOsO 4 , which crystallizes as a scheelite at room temperature, underwent a continuous phase transition to I 4 1 / amd near 550 K. RbRuO 4 and CsOsO 4 were found to crystallize in the orthorhombic ( Pnma ) pseudoscheelite structure, and both displayed discontinuous phase transitions to I 4 1 / a at high temperatures. CsOsO 4 was determined to undergo a phase transition to a P 2 1 / c structure below 140 K. CsRuO 4 crystallizes with a baryte-type structure at room temperature. Upon heating CsRuO 4 a first order phase transition to the scheelite structure in I 4 1 / a is observed at 400 K. A continuous phase transition is observed to P 2 1 2 1 2 1 below 140 K. DC magnetic susceptibility data is consistent with long-range antiferromagnetic ordering at low temperatures for all compounds except for CsOsO 4 , which is paramagnetic to 2 K. The effective magnetic moments are in agreement with the spin only values for an S = 1/2 quantum magnet. Effective magnetic moments calculated for Os compounds were lower than their Ru counterparts, reflective of an enhanced spin orbit coupling effect. A magnetic structure is proposed for RbRuO 4 consisting of predominately antiferromagnetic (AFM) ordering along the 001 direction, with canting of spins in the 100 plane. A small ordered magnetic moment of 0.77 μ B was determined.

The structures of the six perrhenates (AReO4 A = Ag, Na, K, Rb, Cs and Tl) at room temperature have been established using powder neutron diffraction methods. These demonstrate the rigid nature of the ReO4 tetrahedra, with the Re-O distances decreasing very slightly and the O-Re-O bond angles approaching the regular tetrahedron value of 109.5° as the size of the A-type cation increases. Variable temperature synchrotron X-ray diffraction measurements show that RbReO4 undergoes a I41/a to I41/amd transition near 650 K that is associated with a change in the orientation of the ReO4- tetrahedra about the scheelite b-axis associated with a Γ3+ mode. CsReO4 has an orthorhombic pseudo scheelite structure at room temperature with rotation of the ReO4 tetrahedra about the c-axis described by mode M4+ and this undergoes a first order orthorhombic to tetragonal (Pnma to I41/a) transition near 450 K with a transition to the I41/amd structure occurring above this. TlReO4 is a rare example of a crystalline material displaying a re-entrant phase transition; 141/a to P21/c to 141/a. The monoclinic structure can be described as a scheelite superstructure that contains an ordering of tetrahedral rotations around the c-axis and along the b-axis with the irrep Γ3+ and M4+ both present. This behaviour is different to that described recently for the analogous Tc oxide TlTcO4, which highlights the differences in the chemistry of these two systems.

The temperature dependence of the structures of four pertechnetates ( A TcO 4 A = Ag, Tl, Rb, Cs) from 90 K to their melting points is described. Synchrotron X-ray diffraction measurements show that RbTcO 4 undergoes a I 4 1 / a to I 4 1 / amd transition near 530 K that is associated with a change in the orientation of the TcO 4 - tetrahedra about the scheelite b axis. AgTcO 4 also exhibits a tetragonal scheelite type structure, and this is retained between 90 and 750 K, above which it melted. CsTcO 4 has an orthorhombic pseudo-scheelite structure at room temperature and this undergoes a first-order orthorhombic to tetragonal transformation ( Pnma to I 4 1 / a ) near 430 K. TlTcO 4 is isostructural with CsTcO 4 at 90 K, but the orthorhombic to tetragonal transformation proceeds via an intermediate orthorhombic phase. The different behavior found here and described previously for the analogous Re oxide TlReO 4 highlights the differences in the chemistry of these two systems.

The quantum magnet KOsO4 has been characterized by a combination of X-ray and neutron diffraction techniques. The tetrahedrally coordinated Os7+ 5d1S = 1/2 cations were determined to order antiferromagnetically along the c axis below 35 K. A miniscule ordered magnetic moment of 0.46(18) μB was determined per Os7+ cation.

Medulloblastoma (MB) is the most common malignant brain tumor of childhood. Although outcomes have improved in recent decades, new treatments are still needed to improve survival and reduce treatment-related complications. The MB subtypes groups 3 and 4 represent a particular challenge due to their intragroup heterogeneity, which limits the options for "rational" targeted therapies. Here, we report a systems biology approach to drug repositioning that integrates a nonparametric, bootstrapping-based simulated annealing algorithm and a 3D drug functional network to characterize dysregulated driver signaling networks, thereby identifying potential drug candidates. From more than 1300 drug candidates studied, we identified five members of the cardiac glycoside family as potentially inhibiting the growth of groups 3 and 4 MB and subsequently confirmed this in vitro. Systemic in vivo treatment of orthotopic patient-derived xenograft (PDX) models of groups 3 and 4 MB with digoxin, a member of the cardiac glycoside family approved for the treatment of heart failure, prolonged animal survival at plasma concentrations known to be tolerated in humans. These results demonstrate the power of a systematic drug repositioning method in identifying a potential treatment for MB. Our strategy could potentially be used to accelerate the repositioning of treatments for other human cancers that lack clearly defined rational targets., (Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.)

Ruthenium-containing double perovskites A 2 ScRuO 6 have been synthesized as polycrystalline powders and structurally characterized using a combination of synchrotron X-ray and neutron powder diffraction methods. When A = Ba, a hexagonal 6L perovskite structure is obtained if the synthesis is conducted at ambient pressure and a rock-salt ordered cubic structure is obtained if the sample is quenched from high pressures. The Sr oxide Sr 2 ScRuO 6 is obtained with a rock-salt ordered corner sharing topology. Heat capacity and bulk magnetic susceptibility measurements show that the three oxides are antiferromagnets. Cubic Ba 2 ScRuO 6 undergoes a metal-insulator transition near 270 K and hexagonal Ba 2 ScRuO 6 is a semiconductor with an activation energy of 0.207 eV. The magnetic structures of the two rock-salt ordered double perovskites were established using powder neutron diffraction and are described by k = (0,0,1) and k = (0,0,0) for the Ba and Sr oxides, respectively, corresponding to type I antiferromagnetic structures, with ferromagnetic layers stacked antiferromagnetically. The ambient-pressure hexagonal polymorph of Ba 2 ScRuO 6 has partial Sc-Ru ordering at both the face-sharing B 2 O 9 dimer and corner-sharing BO 6 sites. The magnetic structure is described by k = (1/2,0,0) with the basis vector belonging to the irreducible representation Γ 3 .

The crystal and magnetic structures of double perovskites of the type Ba 2-x Sr x YOsO 6 were studied by synchrotron X-ray and neutron powder diffraction methods, bulk magnetic susceptibility measurements, and X-ray absorption spectroscopy. The structures were refined using combined neutron and synchrotron data sets based on an ordered array of corner-sharing YO 6 and OsO 6 octahedra, with the Ba/Sr cations being completely disordered. The structure evolves from cubic to monoclinic Fm3̅m (x ≈ 0.6) → I4/m (x ≈ 1.0) → I2/m (x ≈ 1.6) → P2 1 /n as the Sr content is increased, due to the introduction of cooperative tilting of the octahedra. Bulk magnetic susceptibility measurements demonstrate the oxides are all anti-ferromagnets. The decrease in symmetry results in a nonlinear increase in the Neel temperature. Low-temperature neutron diffraction measurements of selected examples show these to be type-I anti-ferromagnets. X-ray absorption spectra collected at the Os L 3 - and L 2 -edges confirm the Os is pentavalent in all cases, and there is no detectable change in the covalency of the Os cation as the A-cation changes. Analysis of the L 3 /L 2 branching ratio shows that the spin-orbit coupling is constant and insignificant across the series.

The temperature dependences of the structures of three polytypes of BaRuO 3 have been investigated between room temperature and 1000 °C using high resolution synchrotron X-ray diffraction. The structural studies reveal a systematic decrease of the Ru-Ru distance as the pressure required to prepare the polytype increases. The O-O distance across the shared face increases as the Ru-Ru separation decreases. The 9R and 4H polytypes undergo unexceptional changes with increasing temperature. In 6H-BaRuO 3 there is an apparent increase in the Ru-Ru interaction at around 650 °C and a concurrent reduction in the O-O distance, indicating an anomalous strengthening of the Ru-Ru interactions upon heating.