Uranyl Peroxide Oxalate Cage and Core–Shell Clusters Containing 50 and 120 Uranyl Ions

Cage clusters built from uranyl hexagonal bipyramids and oxalate ligands crystallize from slightly acidic aqueous solution under ambient conditions, facilitating structure analysis. Each cluster contains uranyl ions coordinated by peroxo ligands in a bidentate configuration. Uranyl ions are bridged by shared peroxo ligands, oxalate ligands, or through hydroxyl groups. U₅₀Ox₂₀ contains 50 uranyl ions and 20 oxalate groups and is a topological derivative of the U₅₀ cage cluster that has a fullerene topology. U₁₂₀Ox₉₀ contains 120 uranyl ions and 90 oxalate groups and is the largest and highest mass cluster containing uranyl ions that has been reported. It has a core–shell structure, in which the inner shell (core) consists of a cluster of 60 uranyl ions and 30 oxalate groups, identical to U₆₀Ox₃₀, with a fullerene topology. The outer shell contains 12 identical units that each consist of five uranyl hexagonal bipyramids that are linked to form a ring (topological pentagon), with each uranyl ion also coordinated by a side-on nonbridging oxalate group. The five-membered rings of the inner and outer shells (the topological pentagons) are in correspondence and are linked through K cations. The inner shell topology has therefore templated the location of the outer shell rings, and the K counterions assume a structure-directing role. Small-angle X-ray scattering data demonstrated U₅₀Ox₂₀ remains intact in aqueous solution upon dissolution. In the case of clusters of U₁₂₀Ox₉₀, the scattering data for dissolved crystals indicates the U₆₀Ox₃₀ core persists in solution, although the outer rings of uranyl bipyramids contained in the U₁₂₀Ox₉₀ core–shell cluster appear to detach from the cluster when crystals are dissolved in water

Uranyl Peroxide Oxalate Cage and Core–Shell Clusters Containing 50 and 120 Uranyl Ions

Cage clusters built from uranyl hexagonal bipyramids and oxalate ligands crystallize from slightly acidic aqueous solution under ambient conditions, facilitating structure analysis. Each cluster contains uranyl ions coordinated by peroxo ligands in a bidentate configuration. Uranyl ions are bridged by shared peroxo ligands, oxalate ligands, or through hydroxyl groups. U₅₀Ox₂₀ contains 50 uranyl ions and 20 oxalate groups and is a topological derivative of the U₅₀ cage cluster that has a fullerene topology. U₁₂₀Ox₉₀ contains 120 uranyl ions and 90 oxalate groups and is the largest and highest mass cluster containing uranyl ions that has been reported. It has a core–shell structure, in which the inner shell (core) consists of a cluster of 60 uranyl ions and 30 oxalate groups, identical to U₆₀Ox₃₀, with a fullerene topology. The outer shell contains 12 identical units that each consist of five uranyl hexagonal bipyramids that are linked to form a ring (topological pentagon), with each uranyl ion also coordinated by a side-on nonbridging oxalate group. The five-membered rings of the inner and outer shells (the topological pentagons) are in correspondence and are linked through K cations. The inner shell topology has therefore templated the location of the outer shell rings, and the K counterions assume a structure-directing role. Small-angle X-ray scattering data demonstrated U₅₀Ox₂₀ remains intact in aqueous solution upon dissolution. In the case of clusters of U₁₂₀Ox₉₀, the scattering data for dissolved crystals indicates the U₆₀Ox₃₀ core persists in solution, although the outer rings of uranyl bipyramids contained in the U₁₂₀Ox₉₀ core–shell cluster appear to detach from the cluster when crystals are dissolved in water

Briefing students before seeing patients

Ramsden argues that teaching is best defined as 'making learning possible'. Good teachers try to understand and generate the conditions which are most favourable for allowing students to achieve the highest quality learning possible. Generating most favourable conditions in teaching hospitals, however, requires patience and planning. It is an environment where learning opportunities with patients are difficult to forecast. The brief-stay nature of modem hospitals exacerbates the traditional randomness of patient presentation. The clinician-teacher therefore needs to consider ways to '...maximize the educational mileage of the student's learning from the prime time of each experience with the patient'. We propose that briefing students before they see patients can be a very effective way of lessening the untoward impact of this quite volatile teaching-learning environment

(UO₂)₂[UO₄(trz)₂](OH)₂: A U(VI) Coordination Intermediate between a Tetraoxido Core and a Uranyl Ion with Cation–Cation Interactions

A uranyl triazole (UO₂)₂[UO₄(trz)₂]­(OH)₂ (<b>1</b>) (trz = 1,2,4-triazole) was prepared using a mild solvothermal reaction of uranyl acetate with 1,2,4-triazole. Single-crystal X-ray diffraction analysis of <b>1</b> revealed it contains sheets of uranium–oxygen polyhedra and that one of the U­(VI) cations is in an unusual coordination polyhedron that is intermediate between a tetraoxido core and a uranyl ion. This U­(VI) cation also forms cation–cation interactions (CCIs). Infrared, Raman, and XPS spectra are provided, together with a thermogravimetric analysis that demonstrates breakdown of the compound above 300 °C. The UV–vis–NIR spectrum of <b>1</b> is compared to those of another compound that has a range of U­(VI) coordination enviromments

Experimental and Computational Study of a New Wheel-Shaped {[W₅O₂₁]₃[(U^VIO₂)₂(μ‑O₂)]₃}^30– Polyoxometalate

A new wheel-shaped polyoxometalate {[W₅O₂₁]₃[(U^VIO₂)₂(μ-O₂)]₃}^30– has been synthesized and structurally characterized. The calculated electrostatic potential reveals the protonation of several μ-oxo bridges reducing the polyoxometalate total charge. A protonated structure computed at the density functional level of theory (DFT) is in good agreement with the experimental fit. This species presents a classical polyoxometalate electronic structure with well-defined metal and oxo bands belonging to its U/W and oxo/peroxo constituents, respectively. Furthermore, fragment calculations indicate that the electronic structures of the uranyl–peroxide and polyoxotugstate fragments are little affected by the nanowheel assembly

Experimental and Computational Study of a New Wheel-Shaped {[W₅O₂₁]₃[(U^VIO₂)₂(μ‑O₂)]₃}^30– Polyoxometalate

A new wheel-shaped polyoxometalate {[W₅O₂₁]₃[(U^VIO₂)₂(μ-O₂)]₃}^30– has been synthesized and structurally characterized. The calculated electrostatic potential reveals the protonation of several μ-oxo bridges reducing the polyoxometalate total charge. A protonated structure computed at the density functional level of theory (DFT) is in good agreement with the experimental fit. This species presents a classical polyoxometalate electronic structure with well-defined metal and oxo bands belonging to its U/W and oxo/peroxo constituents, respectively. Furthermore, fragment calculations indicate that the electronic structures of the uranyl–peroxide and polyoxotugstate fragments are little affected by the nanowheel assembly

(UO₂)₂[UO₄(trz)₂](OH)₂: A U(VI) Coordination Intermediate between a Tetraoxido Core and a Uranyl Ion with Cation–Cation Interactions

A uranyl triazole (UO₂)₂[UO₄(trz)₂]­(OH)₂ (<b>1</b>) (trz = 1,2,4-triazole) was prepared using a mild solvothermal reaction of uranyl acetate with 1,2,4-triazole. Single-crystal X-ray diffraction analysis of <b>1</b> revealed it contains sheets of uranium–oxygen polyhedra and that one of the U­(VI) cations is in an unusual coordination polyhedron that is intermediate between a tetraoxido core and a uranyl ion. This U­(VI) cation also forms cation–cation interactions (CCIs). Infrared, Raman, and XPS spectra are provided, together with a thermogravimetric analysis that demonstrates breakdown of the compound above 300 °C. The UV–vis–NIR spectrum of <b>1</b> is compared to those of another compound that has a range of U­(VI) coordination enviromments

Expanding the Crystal Chemistry of Uranyl Peroxides: Four Hybrid Uranyl-Peroxide Structures Containing EDTA

The first four uranyl peroxide compounds containing ethylenediaminetetra-acetate (EDTA) were synthesized and characterized from aqueous uranyl peroxide nitrate solutions with a pH range of 5–7. Raman spectra demonstrated that reaction solutions that crystallized [NaK₁₅[(UO₂)₈­(O₂)₈(C₁₀H₁₂O₁₀N₂)₂­(C₂O₄)₄]­·(H₂O)₁₄] (<b>1</b>) and [Li₄K₆[(UO₂)₈­(O₂)₆(C₁₀H₁₂O₁₀N₂)₂­(NO₃)₆]­·(H₂O)₂₆] (<b>2</b>) contained excess peroxide, and their structures contained oxidized ethylenediaminetetraacetate, EDTAO₂^4–. The solutions from which [K₄[(UO₂)₄­(O₂)₂(C₁₀H₁₃O₈N₂)₂­(IO₃)₂]­·(H₂O)₁₆] (<b>3</b>) and LiK₃[(UO₂)₄(O₂)₂­(C₁₀H₁₂O₈N₂)₂­(H₂O)₂]­·(H₂O)₁₈ (<b>4</b>) crystallized contained no free peroxide, and the structures incorporated intact EDTA^4–. In contrast to the large family of uranyl peroxide cage clusters, coordination of uranyl peroxide units in <b>1</b>–<b>4</b> by EDTA^4– or EDTAO₂^4– results in isolated tetramers or dimers of uranyl ions that are bridged by bidentate peroxide groups. Two tetramers are bridged by EDTAO₂^4– to form octamers in <b>1</b> and <b>2</b>, and dimers of uranyl polyhedra are linked through iodate groups in <b>3</b> and EDTA^4– in <b>4</b>, forming chains in both cases. In each structure the U–O₂–U dihedral angle is strongly bent, at ∼140°, consistent with the configuration of this linkage in cage clusters and other recently reported uranyl peroxides

Associations of the candidate <i>FTO</i> SNPs with risk of obesity in a population of school-age children.

<p>A1: mutant allele; A2: wild-type allele.</p><p>Additive model: A1A1/A1A2/A2A2;</p><p>Dominant model: A1A1 + A1A2/A2A2;</p><p>Recessive model: A1A1/A1A2 + A2A2;</p>a<p>: Logistic regression, adjusted for age, gender and location.</p><p>Associations of the candidate <i>FTO</i> SNPs with risk of obesity in a population of school-age children.</p

Association of <i>FTO</i> rs7206790 and rs11644943 with body measurements.

<p>The <i>P</i>-value was calculated with linear regression using the additive model, adjusted for age, gender and location.</p><p>Abbreviations: WC, waist circumference; HC, hip circumference; WHtR, waist circumference to height ratio; BMI, body mass index.</p><p>Association of <i>FTO</i> rs7206790 and rs11644943 with body measurements.</p