Fast lithium-ion conductivity in the 'empty-perovskite' n = 2 Ruddlesden–Popper-type oxysulphide Y₂Ti₂S₂O₅

Materials with Wadsley–Roth (W–R) crystallographic shear and bronze-type structures display fast lithium (Li)-ion diffusion and are of interest as anode materials for high-power Li-ion batteries. Here we use density-functional-theory calculations to investigate Y2Ti2S2O5, a Li-ion anode material that shares structural features with W–R phases. Y2Ti2S2O5 is a layered Ruddlesden–Popper-type oxysulphide displaying a reversible capacity of 128 mA h g−1, with 60% capacity-retention at a charge rate of 20C in micrometer-sized electrode particles. The crystal structure contains an empty central layer of corner-sharing [TiO5S] octahedra, equivalent to a (∞ × ∞ × 2) block of the ReO3-like units that form Wadsley–Roth type phases. Intercalated Li+ ions on this plane occupy distorted ‘rectangular-planar’ sites, and display 2D mobility with single-ion hopping barriers of 64 meV under dilute conditions. The insertion geometry of Li+ is highly frustrated, giving rise to a smooth potential energy surface for Li-hopping and exceptionally low activation barriers. The [TiO5S] units do not experience major distortions or correlated rotations during discharge, due to framework rigidity provided by [Y2S2]2+ rocksalt slabs, meaning the rectangular-planar-like geometry of Li+ is retained across all states of charge. A tetragonal to orthorhombic to tetragonal phase change occurs upon lithiation, with a stable Li+ ordering at x = 1.0 in LixY2Ti2S2O5. Li+–Li+ repulsion has a significant effect on the cation ordering at all Li intercalation levels. Na+ hopping barriers are >1.7 eV, while Mg2+ ions can move with barriers of ∼607 meV, illustrating the how diffusion behaviour varies for ions of different size and charge within W–R-type frameworks. The exceptionally low activation barriers for Li-hopping and well-defined, rigid 2D diffusion plane makes Y2Ti2S2O5 a valuable model system within which to understand Li+ behaviour in high-rate electrode materials, such as the related Wadsley–Roth phases

Thermodynamics and defect chemistry of substitutional and interstitial cation doping in layered α-V2O5

A systematic study of the location and energetics of cation dopants in α-V2O5 has been conducted using pair-potential methods, supplemented by first-principles calculations. The consequences of doping on intrinsic defect equilibria have been discussed and the effects of selected dopants on Li+ and Mg2+ diffusion energy barriers have been investigated

Fat transforms ascorbic acid from inhibiting to promoting acid-catalysed N-nitrosation

<b>Background</b>: The major potential site of acid nitrosation is the proximal stomach, an anatomical site prone to a rising incidence of metaplasia and adenocarcinoma. Nitrite, a pre-carcinogen present in saliva, can be converted to nitrosating species and N-nitroso compounds by acidification at low gastric pH in the presence of thiocyanate. <b>Aims</b>: To assess the effect of lipid and ascorbic acid on the nitrosative chemistry under conditions simulating the human proximal stomach. <b>Methods</b>: The nitrosative chemistry was modelled in vitro by measuring the nitrosation of four secondary amines under conditions simulating the proximal stomach. The N-nitrosamines formed were measured by gas chromatography–ion-trap tandem mass spectrometry, while nitric oxide and oxygen levels were measured amperometrically. <b>Results</b>: In absence of lipid, nitrosative stress was inhibited by ascorbic acid through conversion of nitrosating species to nitric oxide. Addition of ascorbic acid reduced the amount of N-nitrosodimethylamine formed by fivefold, N-nitrosomorpholine by .1000-fold, and totally prevented the formation of N-nitrosodiethylamine and N-nitrosopiperidine. In contrast, when 10% lipid was present, ascorbic acid increased the amount of Nnitrosodimethylamine, N-nitrosodiethylamine and N-nitrosopiperidine formed by approximately 8-, 60- and 140-fold, respectively, compared with absence of ascorbic acid. <b>Conclusion</b>: The presence of lipid converts ascorbic acid from inhibiting to promoting acid nitrosation. This may be explained by nitric oxide, formed by ascorbic acid in the aqueous phase, being able to regenerate nitrosating species by reacting with oxygen in the lipid phase

Genesis, Development and Progress of the United Church of Canada

There is an almost universal demand in Christendom for a union of churches, which will, in some way, give stability and visibility to the unity of all Christians. Throughout the world there are new movements toward unity. In England, Scotland, United States and Canada, in fact the majority of countries where the reform faith is in the strongest, there is a tendency to accentuate the things that unite

Interplay between CCR7 and Notch1 axes promotes stemness in MMTV-PyMT mammary cancer cells

Background: Breast cancer is the major cause of cancer-related mortality in women. It is thought that quiescent stem-like cells within solid tumors are responsible for cancer maintenance, progression and eventual metastasis. We recently reported that the chemokine receptor CCR7, a multi-functional regulator of breast cancer, maintains the stem-like cell population. Methods: This study used a combination of molecular and cellular assays on primary mammary tumor cells from the MMTV-PyMT transgenic mouse with or without CCR7 to examine the signaling crosstalk between CCR7 and Notch pathways. Results: We show for the first time that CCR7 functionally intersects with the Notch signaling pathway to regulate mammary cancer stem-like cells. In this cell subpopulation, CCR7 stimulation activated the Notch signaling pathway, and deletion of CCR7 significantly reduced the levels of activated cleaved Notch1. Moreover, blocking Notch activity prevented specific ligand-induced signaling of CCR7 and augmentation of mammary cancer stem-like cell function. Conclusion: Crosstalk between CCR7 and Notch1 promotes stemness in mammary cancer cells and may ultimately potentiate mammary tumor progression. Therefore, dual targeting of both the CCR7 receptor and Notch1 signaling axes may be a potential therapeutic avenue to specifically inhibit the functions of breast cancer stem cells.Sarah T. Boyle, Krystyna A. Gieniec, Carly E. Gregor, Jessica W. Faulkner, Shaun R. McColl and Marina Kochetkov

Customer rage: Triggers, tipping points, and take-outs

The article presents the results of a study of customer rage, which involved 50 interviews with enraged customers from the U.S., Australia, Thailand and China. It focuses on the psychological processes underlying incidents of customer rage. These are defined as cases where customers become so infuriated at a perceived lack of customer service that they may verbally or physically attack employees, or damage corporate property. It was found that such incidents typically were the result of escalating anger, rather than an immediate reaction. They usually were preceded by a series of interactions with the firm which were perceived as insulting or threatening by the customer

Mg²⁺ storage and mobility in anatase TiO₂: the role of frustrated coordination

Anatase TiO₂ is a candidate high-power electrode material in Li-ion and Na-ion batteries and has been explored as a Mg battery cathode material, although Mg capacity in undoped anatase is limited. Here we use hybrid-exchange density functional theory calculations to investigate the underlying factors affecting Mg intercalation and mobility in anatase. We find that at the dilute limit, Mg ions have 5-fold coordinated insertion sites, and activation barriers for migration are a surprisingly low 537 meV. As the concentration of Mg inserted into the structure is increased, a cooperative distortion of the lattice occurs, contracting the c lattice parameter. The distortion results in stable orderings of Mg ions in sites which are 6-fold coordinated, but also results in migration barriers that exceed 1500 meV in Mg₀.₅ TiO₂ due to a collective relaxation of the host lattice. The total increase in barrier is predominantly a result of the stabilisation of the insertion sites, as opposed to a destabilisation of the activated sites along the migration pathway. The insertion sites in the dilute limit can be described as frustrated, and it is this unfavourable insertion geometry under dilute conditions that allows the Mg ions to migrate with low activation barriers. The limited performance for Mg²⁺ storage can therefore be attributed to the loss of frustrated coordination at high Mg concentration, which restricts Mg mobility and therefore capacity. Strategies to enhance the capacity of Mg in anatase should therefore aim to inhibit the c lattice parameter contraction or otherwise destabilise stable orderings of Mg in Mg₀.₅ TiO₂ to retain the frustrated coordination of Mg ions at high Mg concentrations

MALDI Imaging Mass Spectrometry (MALDI-IMS)—Application of Spatial Proteomics for Ovarian Cancer Classification and Diagnosis

MALDI imaging mass spectrometry (MALDI-IMS) allows acquisition of mass data for metabolites, lipids, peptides and proteins directly from tissue sections. IMS is typically performed either as a multiple spot profiling experiment to generate tissue specific mass profiles, or a high resolution imaging experiment where relative spatial abundance for potentially hundreds of analytes across virtually any tissue section can be measured. Crucially, imaging can be achieved without prior knowledge of tissue composition and without the use of antibodies. In effect MALDI-IMS allows generation of molecular data which complement and expand upon the information provided by histology including immuno-histochemistry, making its application valuable to both cancer biomarker research and diagnostics. The current state of MALDI-IMS, key biological applications to ovarian cancer research and practical considerations for analysis of peptides and proteins on ovarian tissue are presented in this review

Complex nanostructures in diamond

Meteoritic diamonds and synthesized diamond-related materials contain a wide variety of complex nanostructures. This Comment highlights and classifies this structural complexity by a systematic hierarchical approach, and discusses the perspectives on nanostructure and properties engineering of diamond-related materials

Energy storage mechanisms in vacancy-ordered Wadsley-Roth layered niobates

Wadsley–Roth (WR) crystallographic shear structures demonstrate high energy and power densities as Li-ion battery anode materials. We report the (de)lithiation behavior of two WR-derived layered niobates: NaNb_{3}O_{8} and KNb_{3}O_{8}. Both demonstrate multi-electron (Nb5+/Nb3+) redox on the first discharge, reacting with ≈5 mol Li per mol ANb_{3}O_{8}. Li intercalation in NaNb_{3}O_{8} is dominated by Li-diffusion kinetics and evolution of the interlayer structure, with Li initially filling octahedral sites near the interlayer space to draw the layers together to form a (2 × 2)_{∞} WR structure. This average structure change pushes Na ions into the square channels, blocking fast Li diffusion down the square channels that provide the fast Li-ion conduction in most WR materials. Upon charge, Li ions incorporated into the octahedral WR sites (ordered vacancies in the layered structure) are extracted, revealing a new, reversible Li site for additional capacity in WR-like materials. The behavior of KNb_{3}O_{8} is similar, but has additional hysteresis associated with its larger counter-cation. While neither layered niobate matches the demonstrated performance of WR materials, by studying them, we identify a route for increased capacity in WR-like frameworks. Additionally, we identify the important role of Li diffusion kinetics and counter-cations in the cycling behavior of WR-derived structures