Carbon-coated honeycomb Ni-Mn-Co-O inverse opal: a high capacity ternary transition metal oxide anode for Li-ion batteries

We present the formation of a carbon-coated honeycomb ternary Ni-Mn-Co-O inverse opal as a conversion mode anode material for Li-ion battery applications. In order to obtain high capacity via conversion mode reactions, a single phase crystalline honeycombed IO structure of Ni-Mn-Co-O material was first formed. This Ni-Mn-Co-O IO converts via reversible redox reactions and Li2O formation to a 3D structured matrix assembly of nanoparticles of three (MnO, CoO and NiO) oxides, that facilitates efficient reactions with Li. A carbon coating maintains the structure without clogging the open-worked IO pore morphology for electrolyte penetration and mass transport of products during cycling. The highly porous IO was compared in a Li-ion half-cell to nanoparticles of the same material and showed significant improvement in specific capacity and capacity retention. Further optimization of the system was investigated by incorporating a vinylene carbonate additive into the electrolyte solution which boosted performance, offering promising high-rate performance and good capacity retention over extended cycling. The analysis confirms the possibility of creating a ternary transition metal oxide material with binder free accessible open-worked structure to allow three conversion mode oxides to efficiently cycle as an anode material for Li-ion battery applications

The influence of colloidal opal template and substrate type on 3D macroporous single and binary vanadium oxide inverse opal electrodeposition

We report on the electrodeposition of 3D macroporous vanadium oxide inverse opals and binary inverse opals on transparent conducting oxide substrates and stainless steel and thermally oxidized stainless steel substrates. The electrodeposition follows a diffusion limited growth mode to form 3D porous crystalline V2O5 after removal of a colloid photonic crystal template of self-assembled polystyrene spheres. Inverse opals were grown using spheres ranging in diameter from 0.5 μm to 6 μm, and binary inverse opals were also electrodeposited using binary mixtures of sphere sizes. We demonstrate that the ionic diffusion that leads to growth has charge-to-mass Coulombic efficiency ranging from 60–90%, depending on the voltage used. Additionally, the tortuosity in ionic diffusion through the opal to the substrate is significantly increased when large sphere diameter templates and binary opal templates are used. Analysis of the contribution of true substrate active area and the influence of template structure on ionic diffusivity confirms that inverse opal growth is dictated by the size of opal spheres, interstitial void clogging by smaller spheres in binary opals, and the conductivity of the substrate active area. The crystallinity of the inverse opal is consistent and a function of applied voltage, and attains phase pure orthorhombic V2O5

Rutile TiO2 inverse opal anodes for Li-ion batteries with long cycle life, high-rate capability and high structural stability

Rutile TiO2 inverse opals provide long cycle life and impressive structural stability when tested as anode materials for Li-ion batteries. The capacity retention of TiO2 inverse opals (IOs) is greater than previously reported values for other rutile TiO2 nanomaterials, and the cycled crystalline phase and material interconnectivity is maintained over thousands of cycles. Consequently, this paper offers insight into the importance of optimizing the relationship between the structure and morphology on improving electrochemical performance of this abundant and low environmental impact material. TiO2 IOs show gradual capacity fading over 1000 and 5000 cycles, when cycled at specific currents of 75 and 450 mA g−1, respectively, while maintaining a high capacity and a stable overall cell voltage. TiO2 IOs achieve a reversible capacity of ≈170 and 140 mA h g−1 after the 100th and 1000th cycles, respectively, at a specific current of 75 mA g−1, corresponding to a capacity retention of ≈82.4%. The structural stability of the 3D IO phase from pristine rutile TiO2 to the conductive orthorhombic Li0.5TiO2 is remarkable and maintains its structural integrity. Image analysis conclusively shows that volumetric swelling is accommodated into the predefined pore space, and the IO periodicity remains constant and does not degrade over 5000 cycles

Optimizing the structure and yield of vanadium oxide nanotubes by periodic 2D layer scrolling.

Metal oxide nanotubes with wide interlayer van der Waals spaces are important materials for a range of applications from energy storage to catalysis, and from energy efficient catalysts and metal–insulator systems to smart window technologies. Controlling the crystalline quality is critical for the material's physical properties on the nanoscale. We report a systematic investigation into the optimization of structural quality and yield of vanadium oxide nanotubes (VONTs) synthesized by hydrothermal treatment. Usually, interdigitation of alkyl-amine chains occurs between V2O5 lamina, a stitching process that allows scrolling of 2D crystalline sheets into nanotubes with consistently high quality. Through detailed microscopy and spectroscopy examination, we demonstrate that two amine molecules per V2O5 unit optimizes the structure, quality and yield of the VONTs, and that uniform coverage of the juxtaposed V2O5 surfaces in the interlayer spacing minimizes non-uniformities and defects. This observation is consistent for a range of primary amine lengths (hexylamine to hexadecylamine). Through statistical investigation of hundreds of VONTs under each condition, we uncover the effect of amine chain length of V2O5 2D sheet thickness, and mechanism for optimum VONT quality. Finally, we summarize non-uniformities during VONT synthesis including, bending, spiraling and twisting of the scrolled crystalline layers

Vanadium oxide polycrystalline nanorods and ion-exchanged nanotubes for enhanced lithium intercalation.

In this work we investigate two alternative methods to remove amine molecules from as-synthesized vanadium oxide nanotubes (VONTs). Thermal treatment results in the formation of polycrystalline nanorods (poly-NRs) and ion exchange reactions with NaCl result in the formation of Na-VONTs. The removal of amine molecules is confirmed by monitoring the inorganic and organic phase changes and decomposition, respectively, using electron microscopy, IR spectroscopy and X-ray diffraction analyses. We compare the electrochemical performance of as-synthesized VONTs, poly-NRs and Na-VONTs. This work demonstrates that the presence of amine molecules within the layers of vanadium oxide impedes the intercalation of lithium ions, and that their removal results in a significant improvement in electrochemical characteristics. Out of the three vanadium oxide nanostructures investigated, poly- NRs exhibit the most promising results for practical use as a cathode material

Structure of the proton-gated urea channel from the gastric pathogen Helicobacter pylori.

Half the world's population is chronically infected with Helicobacter pylori, causing gastritis, gastric ulcers and an increased incidence of gastric adenocarcinoma. Its proton-gated inner-membrane urea channel, HpUreI, is essential for survival in the acidic environment of the stomach. The channel is closed at neutral pH and opens at acidic pH to allow the rapid access of urea to cytoplasmic urease. Urease produces NH(3) and CO(2), neutralizing entering protons and thus buffering the periplasm to a pH of roughly 6.1 even in gastric juice at a pH below 2.0. Here we report the structure of HpUreI, revealing six protomers assembled in a hexameric ring surrounding a central bilayer plug of ordered lipids. Each protomer encloses a channel formed by a twisted bundle of six transmembrane helices. The bundle defines a previously unobserved fold comprising a two-helix hairpin motif repeated three times around the central axis of the channel, without the inverted repeat of mammalian-type urea transporters. Both the channel and the protomer interface contain residues conserved in the AmiS/UreI superfamily, suggesting the preservation of channel architecture and oligomeric state in this superfamily. Predominantly aromatic or aliphatic side chains line the entire channel and define two consecutive constriction sites in the middle of the channel. Mutation of Trp 153 in the cytoplasmic constriction site to Ala or Phe decreases the selectivity for urea in comparison with thiourea, suggesting that solute interaction with Trp 153 contributes specificity. The previously unobserved hexameric channel structure described here provides a new model for the permeation of urea and other small amide solutes in prokaryotes and archaea

Transparent antireflective layers of oxide nanowires grown from thin films by pressurized contact interdiffusion processes

Oxide phase nanowires are important for applications ranging from optoelectronics to water splitting, but prove difficult to grow in high density with good crystalline quality and phase purity. Heterogeneous catalysts are typically required to nucleate growth. This work demonstrates that dispersions of oxide nanowires can be formed directly from solution processed oxide thin films. We also examine the effect of changes in applied pressure between a solution processed vanadium oxide thin film and a surface-contacted glass coupon on the catalyst-free formation of interconnected sodium vanadate nanowire structures by interdiffusion. Under different applied pressures, meshes of high quality crystalline oxide nanowires formed on the surface, and we examine the nature of phase conversion and nanostructure growth including larger shards composed of multiple conjoined nanowires are also examined. The optical properties of the oxides NWs formed by interdiffusion from oxide thin films show promising properties for application as antireflective coatings across a broadband spectral range. This interdiffusion technique is effective for high quality oxide nanowire growth without catalysts directly from insulating or conducting thin films by direct contact with a source of diffusing species

Narrative review of primary care point-of-care testing (POCT) and antibacterial use in respiratory tract infection (RTI)

Antimicrobial resistance is a global problem and is being addressed through national strategies to improve diagnostics, develop new antimicrobials and promote antimicrobial stewardship. A narrative review of the literature was undertaken to ascertain the value of C reactive protein (CRP) and procalcitonin, measurements to guide antibacterial prescribing in adult patients presenting to GP practices with symptoms of respiratory tract infection (RTI). Studies that were included were randomised controlled trials,controlled before and after studies, cohort studies and economic evaluations. Many studies demonstrated that the use of CRP tests in patients presenting with RTI symptoms reduces antibiotic prescribing by 23.3% to36.16%. Procalcitonin is not currently available as a point-of-care testing (POCT), but has shown value for patients with RTI admitted to hospital. GPs and patients report a good acceptability for a CRP POCT and economic evaluations show cost-effectiveness of CRP POCT over existing RTI management in primary care. POCTs increase diagnostic precision for GPs in the better management of patients with RTI. CRP POCT can better target antibacterial prescribing by GPs and contribute to national antimicrobial resistance strategies. Health services need to develop ways to ensure funding is transferred in order for POCT to be implemented

The emergence and evolution of City Deals in Scotland

There is a resurgent policy emphasis on the role of city-regions as drivers of economic growth. Officials and leaders in such metropolitan areas, however, are confronted with challenges relating to administrative fragmentation, achieving alignment with national policy objectives, and demonstrating the capabilities to plan, finance and deliver effective policy interventions and investments. As a response to these challenges, policymakers are fashioning new governance arrangements, attached to experimental policy mechanisms, to develop urban policy. Of note, City Deals have recently emerged in the UK, and this paper charts their evolution across the UK, with a focus on the devolved administrations in particular. The paper ends with some reflections and questions about their roll out in Scotland