One Site, Two Cations, Three Environments: s2 and s0 Electronic Configurations Generate Pb-Free Relaxor Behavior in a Perovskite Oxide.

The piezoelectric devices widespread in society use noncentrosymmetric Pb-based oxides because of their outstanding functional properties. The highest figures of merit reported are for perovskites based on the parent Pb(Mg1/3Nb2/3)O3 (PMN), which is a relaxor: a centrosymmetric material with local symmetry breaking that enables functional properties, which resemble those of a noncentrosymmetric material. We present the Pb-free relaxor (K1/2Bi1/2)(Mg1/3Nb2/3)O3 (KBMN), where the thermal and (di)electric behavior emerges from the discrete structural roles of the s0 K+ and s2 Bi3+ cations occupying the same A site in the perovskite structure, as revealed by diffraction methods. This opens a distinctive route to Pb-free piezoelectrics based on relaxor parents, which we demonstrate in a solid solution of KBMN with the Pb-free ferroelectric (K1/2Bi1/2)TiO3, where the structure and function evolve together, revealing a morphotropic phase boundary, as seen in PMN-derived systems. The detailed multiple-length-scale understanding of the functional behavior of KBMN suggests that precise chemical manipulation of the more diverse local displacements in the Pb-free relaxor will enhance performance.

Multi-analyser detector (MAD) for high-resolution and high-energy powder X-ray diffraction.

For high-resolution powder diffraction in material science, high photon energies are necessary, especially for in situ and in operando experiments. For this purpose, a multi-analyser detector (MAD) was developed for the high-energy beamline P02.1 at PETRA III of the Deutsches Elektronen-Synchrotron (DESY). In order to be able to adjust the detector for the high photon energies of 60 keV, an individually adjustable analyser-crystal setup was designed. The adjustment is performed via piezo stepper motors for each of the ten channels. The detector shows a low and flat background as well as a high signal-to-noise ratio. A range of standard materials were measured for characterizing the performance. Two exemplary experiments were performed to demonstrate the potential for sophisticated structural analysis with the MAD: (i) the structure of a complex material based on strontium niobate titanate and strontium niobate zirconate was determined and (ii) an in situ stroboscopy experiment with an applied electric field on a highly absorbing piezoceramic was performed. These experiments demonstrate the capabilities of the new MAD, which advances the frontiers of the structural characterization of materials.

The impact of preoperative systemic inflammation on the efficacy of intravenous iron infusion to correct anaemia prior to surgery for colorectal cancer.

AIM: Intravenous iron is increasingly used prior to surgery for colorectal cancer (CRC) to correct iron deficiency anaemia and reduce blood transfusion. Its utility in functional iron deficiency (FID) or anaemia of inflammation is less clear. This observational study examined post-iron infusion changes in haemoglobin (Hb) based on grouping by C-reactive protein (CRP) and ferritin. METHODS: Anaemic (M:Hb < 130 mg/L, F:Hb < 120 mg/L) patients with CRC receiving iron infusion, within a preoperative anaemia detection and correction protocol, at a single centre between 2016 and 2019 were included. Patients were grouped by iron deficiency (ferritin < 30 µg/L and CRP ≤ 5 mg/L, n = 18), FID (ferritin < 30 µg/L and CRP > 5 mg/L, n = 17), anaemia of inflammation (ferritin ≥ 30 µg/L and CRP > 5 mg/L, n = 6), and anaemia of other causes (ferritin ≥ 30 µg/L and CRP ≤ 5 mg/L, n = 6). Median change in Hb and postoperative day (POD) 1 Hb was compared by Kruskal-Wallis test. RESULTS: Iron-deficient patients had the greatest increase in Hb after infusion (24 mg/L), highest POD 1 Hb (108 mg/L), and required no blood transfusions. Patients with FID had the second greatest increase in Hb (15 mg/L) and second highest POD 1 Hb (103 mg/L). Those with anaemia of inflammation had little increase in Hb after infusion (3 mg/L) and lower POD 1 Hb (102 mg/L) than either iron-deficient group. Those without iron deficiency showed a decrease in haemoglobin after infusion (- 5 mg/L) and lowest POD 1 Hb (95 mg/L). CONCLUSIONS: Preoperative intravenous iron is less efficacious in patients with anaemia of inflammation and FID undergoing surgery for CRC, compared with true iron deficiency. Further understanding of the role of perioperative iron infusions is required for maximum gain from therapy.

Crystal structures and phase transition behaviour in the 5d transition metal oxides AReO4 (A = Ag, Na, K, Rb, Cs and Tl).

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.

Review: KRAS mutations are influential in driving hepatic metastases and predicting outcome in colorectal cancer.

Metastatic colorectal cancer (CRC) is a topic of intense research. KRAS mutations have emerged as aggressive drivers of disease. Here we discuss the role of KRAS mutations in metastatic progression of CRC. We describe how KRAS has become a useful biomarker in metastatic CRC and examine where future trials may look to target KRAS mutant tumors for therapeutic benefit.

An algebraic approach to cooperative rotations in networks of interconnected rigid units.

Crystalline solids consisting of three-dimensional networks of interconnected rigid units are ubiquitous amongst functional materials. In many cases, application-critical properties are sensitive to rigid-unit rotations at low temperature, high pressure or specific stoichiometry. The shared atoms that connect rigid units impose severe constraints on any rotational degrees of freedom, which must then be cooperative throughout the entire network. Successful efforts to identify cooperative-rotational rigid-unit modes (RUMs) in crystals have employed split-atom harmonic potentials, exhaustive testing of the rotational symmetry modes allowed by group representation theory, and even simple geometric considerations. This article presents a purely algebraic approach to RUM identification wherein the conditions of connectedness are used to construct a linear system of equations in the rotational symmetry-mode amplitudes.

Lemierre's syndrome: a rare cause of sepsis presenting with an absence of throat symptoms.

A 16-year-old boy presented to hospital with a 6-day history of diarrhoea, vomiting and abdominal pain. During his admission he was found to be hypotensive, tachycardic and persistently feverish. Blood cultures taken on admission isolated Fusobacterium necrophorum CT scanning of his neck showed a non-occlusive thrombus of the right internal jugular vein and a small right parapharyngeal abscess. CT scans of the chest and abdomen revealed multiple pulmonary abscesses, bilateral pleural effusions and splenomegaly. Treatment consisted of an unfractionated heparin infusion and intravenous antibiotics. A right-sided intercostal drain was inserted for a complex right-sided empyema. He subsequently developed a left-sided pleural effusion which was treated with a video-assisted thoracoscopic surgery (VATS) pleurodesis procedure. His fever resolved after his VATS pleurodesis procedure 3 weeks after initial presentation. Clinically he made a slow recovery but now is improved after 6 weeks of intravenous antibiotics and was discharged home.

Prolapsed antrochoanal polyp: an unusual cause of acute adult respiratory distress.

Here we describe an adult male who presented with acute dyspnoea and airway occlusion. Nasoendoscopy revealed a large antrochoanal polyp extending from his maxillary sinus to the level of the epiglottis. The patient underwent a successful semi-emergency polypectomy following initial stabilisation with medication.

Tailoring phase transition temperatures in perovskites via A-site vacancy generation.

The structures across the Sr0.8Ti0.6-xZrxNb0.4O3, 0 ≤ x ≤ 0.6, defect perovskite series were investigated using complementary synchrotron X-ray and neutron powder diffraction data. The locations of second order compositional and temperature dependent phase transitions between the high symmetry cubic Pm3[combining macron]m phase and the lower symmetry tetragonal I4/mcm phase were determined. Deviation of the oxygen x coordinate from the high symmetry value and the B-O-B bond angle from 180° as well as the tetragonal strain squared were each found to be suitable order parameters to monitor the transitions. Tolerance factor calculations confirmed that these A-site deficient perovskites retain a higher symmetry to a lower value than their fully occupied counterparts. Therefore, adjusting vacancy concentrations can be employed as a general strategy to design compounds with specifically tailored phase transition temperatures.

Octahedral tilting in the tungsten bronzes.

Possibilities for 'simple' octahedral tilting in the hexagonal and tetragonal tungsten bronzes (HTB and TTB) have been examined, making use of group theory as implemented in the computer program ISOTROPY. For HTB, there is one obvious tilting pattern, leading to a structure in space group P63/mmc. This differs from the space group P63/mcm frequently quoted from X-ray studies ­ these studies have in effect detected only displacements of the W cations from the centres of the WO6 octahedra. The correct space group, taking account of both W ion displacement and the octahedral tilting, is P6322 ­ structures in this space group and matching this description have been reported. A second acceptable tilting pattern has been found, leading to a structure in P6/mmm but on a larger '2 × 2 × 2' unit cell ­ however, no observations of this structure have been reported. For TTB, a search at the special points of the Brillouin zones revealed only one comparable tilting pattern, in a structure with space-group symmetry I4/m on a '2(1/2) × 2(1/2) by 2' unit cell. Given several literature reports of larger unit cells for TTB, we conducted a limited search along the lines of symmetry and found structures with acceptable tilt patterns in Bbmm on a '2(1/2)2 × 2(1/2) × 2' unit cell. A non-centrosymmetric version has been reported in niobates, in Bbm2 on the same unit cell.

Structural and magnetic studies of perovskite YCr(0.5)Mn(0.5)O3.

The structure of YCr(0.5)Mn(0.5)O6, established from Rietveld refinement of powder neutron diffraction data, contains Cr and Mn that are disordered on the octahedral sites. The structure is best described in the orthorhombic space group Pbnm. Low temperature neutron diffraction data reveal a G-type antiferromagnetic type arrangement, with a ferromagnetic component along the b-axis, indicating that the Cr and Mn couple ferro (or possibly ferri) magnetically to each other.

Sodium uptake in cell construction and subsequent in operando electrode behaviour of Prussian blue analogues, Fe[Fe(CN)6](1-x)·yH2O and FeCo(CN)6.

The development of electrodes for ambient temperature sodium-ion batteries requires the study of new materials and the understanding of how crystal structure influences properties. In this study, we investigate where sodium locates in two Prussian blue analogues, Fe[Fe(CN)6]1-x·yH2O and FeCo(CN)6. The evolution of the sodium site occupancies, lattice and volume is shown during charge-discharge using in situ synchrotron X-ray powder diffraction data. Sodium insertion is found to occur in these electrodes during cell construction and therefore Fe[Fe(CN)6]1-x·yH2O and FeCo(CN)6 can be used as positive electrodes. NazFeFe(CN)6 electrodes feature higher reversible capacities relative to NazFeCo(CN)6 electrodes which can be associated with a combination of structural factors, for example, a major sodium-containing phase, ∼Na0.5FeFe(CN)6 with sodium locating either at the x = y = z = 0.25 or x = y = 0.25 and z = 0.227(11) sites and an electrochemically inactive sodium-free Fe[Fe(CN)6]1-x·yH2O phase. This study demonstrates that key questions about electrode performance and attributes in sodium-ion batteries can be addressed using time-resolved in situ synchrotron X-ray diffraction studies.