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Highlights: [•] We developed and tested a new oral ETEC vaccine in mice, alone and with an adjuvant. [•] The vaccine contains E. coli overexpressing CFA/I, CS3, CS5 and CS6 and B-subunit. [•] Oral immunization induced intestinal and serum antibody responses to all antigens. [•] These responses were further enhanced by dmLT, a nontoxic E. coli adjuvant. [•] The vaccine, both with and without dmLT, was stable and well tolerated. [ABSTRACT FROM AUTHOR]

We consider the identification of cracks in an elastic 2D or 3D waveguide with the help of a modal version of the linear sampling method. The main objective of our paper is to show that since the usual crack in elasticity is traction free, that is, the boundary condition on the lips of the crack is a priori known to be of Neumann type, we shall adapt the formulation of the sampling method to such a boundary condition in order to improve the efficiency of the method. The need for such adaptation is proved theoretically and illustrated numerically with the help of 2D examples. [ABSTRACT FROM AUTHOR]

This article is devoted to a new method to find defects in some elastic-plastic structure in the antiplane case from overdetermined data on a subpart of its boundary. This iterative method merges the method of quasi-reversibility and a simple level set technique. The foundations of the method are justified from a theoretical point of view and its efficiency is shown with the help of numerical experiments. [ABSTRACT FROM AUTHOR]

In this study, voids commonly associated with tin particles in two aluminium alloys containing microalloying additions (0.01 at.%) of tin have been observed by transmission electron microscopy. The voids were generated by quenching the alloys at moderate rates (102-103 K s-1) from a temperature (718 K) in excess of the melting temperature (501 K) of elemental tin in tin-microalloyed aluminium. Estimates of the void volume as a function of the volume of the associated tin particle reveal a linear relationship consistent with the excess volume resulting from the solidification of the tin particle. The formation and stabilisation of shrinkage voids in metallic alloys are suggested to arise from a combination of high vacancy supersaturation, the large volumetric misfit strain of the solidifying tin particle and a reduction in void surface energy associated with segregation of alloying elements. [ABSTRACT FROM AUTHOR]

Abstract: The work hardening of a model Al–3Cu–0.05Sn (wt.%) alloy containing shear-resistant θ′ (Al2Cu) precipitate plates was studied as a function of precipitate state. The mechanical response was monitored using both tension and tension–compression (Bauschinger) tests so that the isotropic and kinematic contributions to the work hardening could be separated. The undeformed and deformed structures were characterized using TEM. The kinematic hardening was modeled using the recent approach of Proudhon et al. [19], and good agreement was found for both the absolute magnitude and the strain evolution of the internal stress as a function of precipitate state. The isotropic hardening was modeled using a modified form of the Kocks–Mecking–Estrin approach, taking into account the contribution to the forest dislocation density from the plastic relaxation around the precipitate plates that accompanies the saturation in the internal stress during straining. In this way, the evolution of the isotropic and kinematic hardening during straining are coupled, and the dual role of the precipitates in contributing to both modes is emphasized. Finally a parametric analysis of the model is performed to identify the changes in microstructural parameters that will allow simultaneous increases in both yield strength and uniform elongation. It is suggested that increasing the precipitate number density of this system will achieve this end. [Copyright &y& Elsevier]

Abstract: A careful transmission electron microscopy (TEM) investigation of an incommensurately modulated member of the (Bi1− x Sr x )Fe3+O3− x /2□ x /2, 0.2≤x≤0.67, solid solution has been carried out. High resolution (HR) TEM imaging is used to show the presence of at least 6-fold twinning on a rather fine (∼5nm) scale. The (3+1)-d superspace group symmetry is suggested to be or one of the non-centrosymmetric sub-groups thereof, namely , , and . A superspace construction is then used to propose the nature of the local compositional ordering and, hence, of the oxygen-deficient slab that intergrows with the perovskite slab to produce the observed solid solution phase. The proposed compositional superspace atomic surfaces can be used to produce model structures at any composition within the solid solution range. [Copyright &y& Elsevier]

Abstract: Using a contact delay-line ultrasonic device, we measured the elastic properties particularly the shear modulus μ of pure plutonium and uranium–vanadium alloy from ambient temperature to 900K. Several allotropes of these materials have been detected in the explored temperature range. For plutonium metal, measurements reveal a collapse of μ(T) of about 50% for the α→β phase change and a small increase of 0.2% for the β→γ phase change. For uranium–vanadium alloy, we observe a monotonic decrease of about 50% of μ(T) for the α→β phase change. In order to include the phase transition to describe the variation of μ(T), a model has been proposed and applied. [Copyright &y& Elsevier]

Abstract: We consider an inverse scattering problem in a 3D homogeneous shallow ocean. Specifically, we describe a simple and efficient inverse method which can compute an approximation of the vertical projection of an immersed obstacle. This reconstruction is obtained from the far-field patterns generated by illuminating the obstacle with a single incident wave at a given fixed frequency. The technique is based on an implementation of the theory of the convex scattering support [S. Kusiak, J. Sylvester, The scattering support, Commun. Pure Appl. Math. (2003) 1525–1548]. A few examples are presented to show the feasibility of the method. [Copyright &y& Elsevier]

The formation of particles of elemental tin in association with the nucleation of the precipitate phase θ′ in an Al–1.7  at.%  Cu–0.01  at.%  Sn alloy has been investigated by high resolution transmission electron microscopy. Analysis of lattice images has demonstrated that these tin particles associated with θ′ platelets formed during short-term ageing (typically 3  min at 200°C) exhibit a crystallographic form that is distinctly different from that previously reported in such ternary alloys and also from that observed in the binary alloy Al–0.01  at.%  Sn. Those tin particles that could be clearly identified as β-Sn phase shared a crystallographic relationship of the form (001)Sn|(001)Al|(001)θ′, [110]Sn|[100]Al  |  [100]θ′ with the α-Al and θ′ phases with which they were simultaneously in contact. The observations imply that, while tin may assist nucleation of platelets of θ′, the formation of θ′ equally influences the crystallography of β-Sn that forms in association with θ′. Following prolonged ageing (typically 50  h at 200°C), the β-Sn particles in contact with θ′ plates had coarsened and diminished in number, and most now exhibited an orientation relationship with α-Al matrix similar to that observed in the binary alloy Al–0.01  at.%  Sn (i.e. (100)Sn) and to that previously observed in the later stages of ageing of the ternary alloy Al–1.7    at.%    Cu–0.01  at.%  Sn. [ABSTRACT FROM AUTHOR]

Very recently 63 Cu  NMR has been shown to be extremely sensitive in detecting and differentiating between the precipitate phases that form in Al–Cu alloys during heat treatment. This technique is now used to quantify the effectiveness of small additions of Sn to the alloy Al–1.7  at.%  Cu in promoting the rapid nucleation and growth of the θ′-phase precipitate. Two parallel series of 63 Cu  NMR spectra were recorded for Al–1.7  at.%  Cu and Al–1.7  at.%  Cu–0.01  at.%  Sn: (i) aged at 130° C to observe the comparative rate of phase evolution and (ii) aged at 200° C to observe the rate of growth of θ′-phase and to compare with the Vickers hardness of the alloys aged at 200° C for similar periods. Evidence is presented that a metastable precursor phase to θ′ (labelled ) is formed in Al–Cu–Sn which transforms to θ′ on further aging. [ABSTRACT FROM AUTHOR]

Abstract: Indium oxide (In2O3)-coated titanium dioxide (TiO2) core-shell nanostructures were produced via a sol–gel route. The presence of the thin In2O3 shell was established by X-ray photoelectron spectroscopy (XPS) and the morphology was investigated by high-resolution transmission electron microscopy (HRTEM). It was found that the In2O3 content increased with increased number of coatings on the TiO2 nanostructure. Lattice fringes were observed for the nanosized TiO2 particles, and the In2O3 shell showed an amorphous structure revealing a clear distinction between the core and shell materials. These morphologies were supported by energy dispersive X-ray analysis to further validate the presence of a core-shell structure. [Copyright &y& Elsevier]

The quasicrystal structure of primary intermetallic particles found in the ascast microstructure of a permanent mould-cast Mg-8wt%Zn-4wt%Al alloy has been characterized using transmission electron microscopy. Most primary intermetallic particles have an average composition of Mg[sub 9±2]Zn[sub 4±1]Al[sub 3±1] and a primitive icosahedral structure, with a quasilattice parameter of 0.515nm and a point group of m35. The metastable quasicrystalline phase persists for extended periods at elevated temperatures; while the volume fraction decreases with thermal exposure at 325°C, the decrease is small up to 120h and a fraction persists after 720h. There is no evidence of transformation of or within the quasicrystalline phase during this period. Instead, the metastable quasicrystalline phase is gradually replaced by the equilibrium Φ phase (Mg[sub 21](Al,Zn)[sub 17]; space group, Pbcm). The relationship between the quasicrystalline phase, its cubic approximant T phase (Mg[sub 32](Al,Zn)[sub 49]; space group, Im3) and the Φ phase is discussed. [ABSTRACT FROM AUTHOR]

The structure of carbon (C) and boron nitride (BN) columnar particles produced alongside by heat-treating a turbostratic B-C-N compound was investigated by analytical transmission electron microscopy. The particles were shown to be helical cones with a well-defined apex, and a helical pitch equal to usually one and at most two layers. The cone apex angle distribution was found to be centred on different values for C and BN. These results strongly suggested that BN and C cones nucleated from different ring defects in the hexagonal networks: square-like ring defects in BN and pentagon-like ring defects in C. These observations were consistent with the supposition that the creation of non B-N bonds and hence odd-membered rings is avoided in BN. Such restriction in BN could also allow one to understand the observed morphological differences between C and BN cones, and in particular the relative difficulty for BN cone edges to join via curved sheets. [ABSTRACT FROM AUTHOR]

A disordered material consisting of graphitic nanoparticles bound together by sharing of their outer graphitic sheets is investigated by high-resolution transmission electron microscopy. Detailed image analysis, including the effect of tilting the specimen, showed that the nanoparticles were often joined together via covalent and van der Waals cross-links, which explained the observed absence of dangling edges. From these observations a model whereby the nanoparticles are all interconnected via cross-links is proposed. A comparison between this material and aggregates of closed single shells found in the same sample as well as with other observations of carbon arc deposits led to an overview of a surprising variety of graphitic morphologies. Suggestions about the possible formation mechanisms for the cross-linked network as well as some similarities with glassy carbon are also discussed. [ABSTRACT FROM AUTHOR]

Investigates the relation between marital distress, therapeutic alliance formation, and treatment outcome in a group marital skills training program in which 63 couples met for 9 weekly 3-hour sessions. Assesses treatment outcome before and after completion of treatment through a series of self-report measures. Determinant of successful treatment; Method; Results.

Abstract. Nanotubes exhibiting a novel structure - boron nitride (BN) conical nanotubes whose walls consist of conical layers with their cone axis parallel to the tube axis, as opposed to ordinary nanotubes, composed of concentric cylindrical layers with their normal perpendicular to the tube axis - were synthesized simultaneously with BN nanotubes by using carbon nanotubes (CNTs) as templates. The diameters of the BN conical nanotubes are typically about 15 nm, which is similar to those of the starting CNTs. Apex angles and inner diameters of most BN conical nanotubes are about 40 degrees and 1 nm, respectively. The lengths of the BN conical nanotubes range from 50 nm to up to several micrometers. PACS: 81.05.Tp; 81.20.-n [ABSTRACT FROM AUTHOR]

All-solid-state thin film batteries based on sputtered pyrite electrodes, a lithium phosphorus oxynitride electrolyte and a lithium anode were prepared and characterized. The successive reduction of both S 2 2 − and Fe 2 + species led to an impressive volumetric discharge capacity, five times higher than the one for LiCoO 2 . Excellent reversibility and capacity retention were obtained during the first and the subsequent 800 charge–discharge cycles. A continuous cycling in the low voltage domain was found to be detrimental to the reversibility of the conversion reaction, suggesting a progressive evolution of the phase distribution inside the electrode. The initial capacity was easily recovered after few full oxidation cycles. [ABSTRACT FROM AUTHOR]

This paper reports the direct transformation of raw lignocellulosic biomass into nanostructured graphitic carbon in a single step. Catalytic iron carbide nanoparticles are generated in situ by thermal decomposition of absorbed iron nitrate followed by carbothermal reduction. The Fe3C particles then etch through the biomass to generate intertwined graphitic tubules through catalytic graphitization. The materials are mesoporous with the pore size dependant on the iron content. Conversion of raw biomass into stable graphitic carbon at relatively low temperatures (800 °C) offers a promising route to large-scale and sustainable synthesis of carbons for electrode or filtration applications. This facile method can also be used to produce nanocomposites of Fe3C/graphite combined with nanoparticles of metal oxides such as CaO or MgO, again from a one-pot precursor, giving potential for a wide range of applications. [ABSTRACT FROM AUTHOR]

Precipitation of Q laths/rods in some age-hardenable aluminium alloys has been traditionally accepted to occur with a single orientation relationship with the α-Al matrix. In this study, the orientation relationships of Q precipitates are characterized by atomic resolution high-angle annular dark-field scanning transmission electron microscopy. Contrary to the long-standing view, multiple orientation relationships are found between Q precipitates and the α-Al matrix. These orientations are correlated by rigid-body rotations about the long axes of the Q laths/rods. [ABSTRACT FROM AUTHOR]

Abstract: Single defocused transmission electron microscope phase contrast images are used to reconstruct the projected thickness map of a single-material object. The algorithm is non-iterative and stable, and we extend it to account for the presence of spherical aberration in the objective optics. The technique can reconstruct the projected thickness map of general single-material objects in the strong phase/weak amplitude regime. It is sensitive to any excursions in the projected thickness from the average, and ideal for examining voids and free volume accumulation in amorphous/glassy materials at the nanometer scale. The resolution of the technique depends on the choice of defocus and the thickness of the specimen. In a certain regime, we demonstrate that variations in the transverse projected thickness with a lateral diameter of may be detected. We use our algorithm to quantitatively reconstruct the projected thickness of latex sphere test specimens from single defocused electron micrographs. We demonstrate that the reconstruction has a large tolerance for error in the input parameters. Simulations confirm that the technique is quantitative, and demonstrate that the origin of low-frequency artifacts is an instability due to noise. We show that the autocorrelation of the projected thickness map may be used to measure the size of open structures in the object using both simulation and latex sphere data. [Copyright &y& Elsevier]

Abstract: State-of-the art atom probe tomography (APT) combined with transmission electron microscopy (TEM) were used to investigate the microstructure at different stages of the ageing process of an alloy of composition (at%) Al–1.68%Cu–4.62%Li–0.33%Mg–0.1%Ag. These alloys were shown to exhibit a complex microstructure of T1 plates and several metastable phases, including θ′ and S. We will highlight the early stages of clustering, precipitate interactions and possible solute segregation at the matrix/precipitate interfaces and detail the chemical composition of the different phases. [Copyright &y& Elsevier]

Abstract: Lattice dynamics of nickel hydroxide, β-Ni(OH)2, electrode material for current batteries, has been investigated by incoherent inelastic neutron scattering. Results are discussed through comparison with the isostructural and well studied model compound, Mg(OH)2. The zone-center phonon spectra calculated in the frame of the density functional theory showed the important role of the spin–spin interactions in nickel hydroxide. Analysis of the calculated force constant matrix provided some insight into peculiarities of interatomic interactions in these layered compounds. A similar theoretical approach is applied to the investigation of the atomic structure and lattice dynamics of the β-NiOOH phase. [ABSTRACT FROM AUTHOR]

Abstract: The precipitate strengthening increment arising from a reasonably monotonic distribution of plate-shaped shear-resistant precipitates in an Al matrix is considered theoretically in terms of the average stress required to push dislocations between the particles. The radius of the solute diffusion field surrounding the tips of the plates is shown to be a key microstructural parameter in controlling the distance of closest approach between precipitates and therefore the maximum strengthening increment. Three new strategies for enhancing the strengthening increment are proposed based on minimizing the size of the solute diffusion fields surrounding plates. These approaches are contrasted with those previously advocated. A model Al–Cu alloy containing plate-shaped, shear-resistant θ′ (Al2Cu) precipitates is used to experimentally test the predictions of the proposed strengthening description. Quantitative agreement between experiment and theory is observed under isothermal annealing conditions at 473K. Furthermore, one of the strategies advocated for increasing the strengthening response is the use of a decreasing transformation temperature. This is tested experimentally at three temperatures and the peak strengthening increment is shown to be in excellent agreement with the theoretical predictions. This work suggests a reinterpretation of the origins of the strengthening observed in current high-strength Al alloys containing plate-shaped precipitates is required. [Copyright &y& Elsevier]

A new family of quaternary carbon and nitrogen containing Rare Earth (RE: Sc, Y, Ho, Er, Tm and Lu) borides: REB15.5CN, has been synthesized and structurally characterized by powder X-ray diffraction data. They are all isotypic with Sc1−xB15.5CN whose structure was solved based on single-crystal X-ray data and HRTEM investigations. The structure refinement converged at a R(F2) value of 0.044 for 364 reflections. The new structure type of Sc1−xB15.5CN is composed of a three-dimensional network based on interconnected slabs of boron (B12)ico icosahedra and (B6)oct octahedra. A linear [CBC] chain and nitrogen tightly bridges icosahedra. Sc partially occupies voids in the sheets of boron octahedra. It crystallizes with the trigonal space group P3m1, with Z=2. Lattice parameters (nm) are as follows: for RE: Sc, a,b=0.5568(4), c=1.0756(2); Y, a,b=0.55919(6), c=1.0873(2); Ho, a,b=0.55883(7), c=1.0878(6); Er, a,b=0.55889(5), c=1.0880(6); Tm, a,b=0.5580(1), c=1.0850(6); Lu, a,b=0.55771(9), c=1.0839(4). Magnetic characterization of ErB17C1.3N0.6 has been performed. [Copyright &y& Elsevier]

Neves-Corvo mine (SOMINCOR, Portugal) is one of the most important underground mines now operating in Europe. It treats a heterogeneous massive sulphide deposit, which is mainly copper and/or tin rich. The extracted ore is processed to obtain two types of concentrates (Cu and Tin) whose purity is affected by some minor (As and Sb) and trace (Hg, Se, Cd) elements. In addition to the concentrate sales, silver is also commercialized as a bonus product. The present work intends to identify the mineral bearer of some of these additional detrimental or bonus elements, and to develop a mineralogical model for predicting mineral processing production profits. Many laboratory-scale tests were conducted to study the behavior of minerals: the different steps and conditions of these tests allow good reproduction of the industrial flotation process of the Neves-Corvo mine. The statistical analyses of the elemental distributions give interesting results and provide the ingredients from which we can produce a preliminary predicting tool. Thus, fahlores-minerals (tetrahedrite and tennantite), which are considered to be veritable toxic trash minerals, can be easily localized during the process. This will allow their separation by modifying the flow sheet to improve the concentrate quality. [Copyright &y& Elsevier]

The analogy between carbon nanotubes and synthetic imogolite, an aluminosicate of stoichiometry (OH) [sub 3]Al[sub 2]O[sub 3]SiOH, having a tubular structure of external diameter 2.4 nm and internal diameter 0.9 nm, is examined. Highresolution transmission electron microscopy, image matching and electron diffraction are used to examine the tube structure. Some interesting new results are obtained, concerning the various states of aggregation of the imogolite tubes, ranging from randomly oriented single tubes to essentially close-packed arrays. Both longitudinal and cross-sectional images were obtained. Some possible applications of imogolite as new materials are discussed. The various imogolite textures pose challenging problems for solid-state physicists, concerning for example the transport and optical properties of such fibre bundles. [ABSTRACT FROM AUTHOR]

Abstract: Catalyst-free boron nitride (BN) and carbon (C) nanoflakes have been produced by direct radio frequency (RF)-magnetron sputtering on molybdenum and tungsten substrates at or above temperatures of 1000°C and 800°C, respectively. Selected-area electron diffraction (SAED) shows that the films are polycrystalline and contain disordered graphite and hexagonal BN. Transmission electron microscopy (TEM) reveals curved or twisted flakes up to several hundred nanometres in length. High resolution transmission electron microscopy (HRTEM) confirms the nanoflake structure to be turbostratic, which is intermediate between an amorphous phase and the ordered layered phases of hexagonal BN or graphite. [Copyright &y& Elsevier]

The influence of Si concentrations on AlTiN and AlTiCrN coatings deposited by PVD has been investigated by using high-resolution characterization techniques: TEM, Dynamic SIMS, Atom Probe Tomography (APT) analyses and nano hardness measurements. First, investigations focus on crystallographic phase stability, microstructural observations and micromechanical studies to understand the effect of the Si addition on these two nitride coatings. Second, the oxidation mechanisms and the kinetics of oxide growth at 950 °C for various durations are examined. Results indicate that the addition of Si introduces high compressive stresses in both coating groups, reaching values in the range of − 6 GPa. However, the behavior of Si content differs for AlTiN coatings with and without chromium. In AlTiSiN coatings, increasing Si addition leads to reduce residual stresses, while no significant change is observed for AlTiCrSiN coatings. This stress evolution is associated with a decrease in crystallinity density of the TiAlN coatings due to Si addition, but this structural phenomenon is not observed when Si is added to the quaternary metallic coatings TiAlCrN. Si content also influences the nanohardness, but the variation among coating is not substantial, with values around 34 + /− 2 GPa, and an elastic-modulus around 443 + /− 40 GPa. Regarding oxidation resistance at 950 °C, the addition of Si in AlTiN coating results in the formation of an external alumina oxide layer and beneath it, a nanometer sized TiO 2 anatase crystallites layer. After the growth of this bi-layer oxide scale, the inward cationic diffusion of the oxygen is very significantly reduced, and it can explain its high oxidation resistance. In contrast, for AlTiCrSiN coatings, the oxide scale morphology is different, consisting of a pure TiO 2 rutile outer layer, followed by an Al-rich oxide and a mixed oxide region of (AlCr) 2 O 3 with small islands of TiO 2. The growth of this last oxide scale shows a regular increase over time, primarily driven by inward oxygen diffusion at the nitride coating interface. [Display omitted] • Cr allows better stability of the crystallinity structure when the addition of Si is done. • AlTiN coating can only be resistant against oxidation at 950 °C if it contains an addition of Si between 1 and 5 at%. • AlTiSiN oxide layer comprises an outer Al 2 O 3 layer and an inner TiO 2 layer containing SiN/O at the grain boundaries. • AlTiCrSiN oxide layer at 950 °C consists of TiO 2 / Al(Cr) 2 O 3 / (Cr,Al) 2 O 3 -TiO 2 -Si from the surface to the nitride interface. • Growth of oxide scale on AlTiCrSiN coatings is controlled by the inward oxygen diffusion until the nitride interface. [ABSTRACT FROM AUTHOR]

• Ta introduction strongly decreases the 850 °C oxidation rate in TiAlN and TiAlYN. • Y introduction increases the room temperature hardness significantly in TiAlN and TiAlTaN. • Thicker oxide layer causes less wear in running-up stage of ball-on-disk wear test. A comparative study of as-deposited structural properties, oxidation and wear properties of industrially arc-deposited Ti-Al-N, Ti-Al-Y-N, Ti-Al-Ta-N and Ti-Al-Ta-Y-N is presented. In the as-deposited coatings, Ta leads to more compressive stress while Y reduces the compressive stress but increases the nanohardness. The nanohardness of Ti-Al-Ta-Y-N is shown to be dominated by Y while its oxidation rate is dominated by Ta. Interestingly, Ta specifically favours the growth of oxide at the interface between Al-rich and Ti-rich oxide layers.In 850°C ball-on-disk wear tests, there is a pronounced effect of the running-in stage, which in turn depends strongly on the oxidation properties of the coating.The transferability of these findings to industrial machining at higher temperatures are discussed. [ABSTRACT FROM AUTHOR]

Abstract Nickel-cobalt oxide is synthesized in combination with electrochemically reduced graphene oxide (Er-GO) by one-step electrodeposition on stainless steel followed by thermal treatment. The presence of reduced graphene oxide leads to enhanced electrochemical response, with a capacity increase from 113 mA h g−1 to 180 mA h g−1, and to increased faradaic efficiency and rate capability. Compared to Ni-Co oxide, the addition of reduced graphene oxide increases capacity retention from 58% to 83% after 5000 cycles. The material fade during cycling is studied by means of electrochemical impedance spectroscopy, electron diffraction spectroscopy and scanning electron microscopy. As a result, different degradation mechanisms are identified as source of the capacity decay, such as microstructural cracking, phase transformation and parasitic reactions. Graphical abstract Image 1 Highlights • Nickel-cobalt oxide/reduced graphene oxide thin-film one-step electrodeposition. • Enhanced performance of 180 mA h g−1 and 83% capacity retention after 5000 cycles. • Degradation phenomena study by EIS alongside SEM and cyclic voltammetry. [ABSTRACT FROM AUTHOR]

Long-period stacking-ordered (LPSO) structures in Mg alloys have received considerable attention in the past decade due to their unique crystallographic features, but their precise structures are still not fully established. In this work, the 18R LPSO structure in two Mg–Y–Al alloys, in both cast and homogenized conditions, is systematically investigated using atomic-scale high-angle annular dark-field scanning transmission electron microscopy and density functional theory. Our observations reveal that there exist at least four types of building clusters—three of them being metastable and hitherto unreported—in the 18R structure in the as-cast condition. Each of the four types of building clusters comprises three Al–Y cubes that are connected by one Mg–Y cube. After annealing at 530–550 °C for 47–48 h, the three metastable building clusters transform to a stable configuration that is characterized by the Al 6 Y 8 L1 2 -type building cluster. These transformations are validated by first-principles calculations. Based on the experimental observations and computational results, the evolution of the building clusters in the 18R structure is elaborated. [ABSTRACT FROM AUTHOR]

With the aim of developing 3V all-solid-state lithium microbatteries, Fe 2 (MoO 4 ) 3 thin films were prepared by radiofrequency magnetron sputtering from a home-made Fe 2 (MoO 4 ) 3 target using optimized sputtering conditions. In addition to elemental analyses, Mössbauer spectroscopy and XPS analyses, showing that Mo 6+ and Fe 3+ are the main detected species, confirmed the stoichiometric character of the films. Post-deposition annealing was necessary to form well-crystallized thin films. The best electrochemical performance was obtained with those annealed at 500 °C which were able to deliver a stable reversible capacity close to the theoretical one, i.e. 2 Li + per Fe 2 (MoO 4 ) 3 formula unit. The corresponding voltage curve displays a plateau with a low hysteresis located at 3.0 V/Li + /Li and related to the Fe 2 (MoO 4 ) 3 – Li 2 Fe 2 (MoO 4 ) 3 two-phase system. Therefore, it was demonstrated for the first time the possible use of Fe 2 (MoO 4 ) 3 thin films as positive electrodes for 3 V lithium microbatteries. [ABSTRACT FROM AUTHOR]

The bond-orientational order parameters introduced by Steinhardt et al. [Phys. Rev. B 28, 784 (1983)] have been an invaluable measurement tool for assessing short-range order in disordered, close-packed assemblies of particles in which the particle positions are known. In many glassy systems the measurement of particle position is not possible or limited (field of view, thickness, resolution) and the bond-orientational order parameters cannot be measured, or adequately sampled. Here we calculate a set of rotationally averaged, projected bond-orientational order parameters that reflect the symmetries of close-packed particle clusters when projected onto a plane. We show by simulation that these parameters are unique fingerprints that can be directly compared to angular correlations in limited-volume, transmission geometry, diffraction patterns from close-packed glassy assemblies. [ABSTRACT FROM AUTHOR]

Thin film positive electrodes of lithium-rich manganese oxide spinels were prepared by radiofrequency magnetron sputtering from a LiMn 2 O 4 ceramic target at a total pressure close to 2 Pa. Post-annealing treatments were necessary to get well-crystallized thin films displaying interesting electrochemical performances. Raman spectrum exhibiting several well-defined bands between 296 and 635 cm −1 is typical for the lithium-rich spinel. Based on ICP, RBS and XRD analyses, the thin films composition is close to Li 1.2 Mn 1.8 O 4 . The latter is also in accordance with a Mn 3+ /Mn 4+ ratio close to 0.1 deduced from XPS measurements. Best electrochemical performance (capacity value, cycling life) between 2 V and 3.5 V vs Li + /Li was obtained for thin films annealed at 600 °C. A volumetric capacity of 52 μAh cm −2 μm −1 (close to about 90% of the theoretical value) was obtained at the first cycle at a C/100 regime. Contrary to most studies carried out on spinel thin films cycled in the 3 V range, no appreciable degradation of the discharge capacity was observed after few tens of cycles at room temperature, highlighting the beneficial effect of substituting 20% of Mn ions by Li ions and the presence of microvoids in thin films that limits the effect of strain generated from volume variation during the Li insertion/deinsertion process. [ABSTRACT FROM AUTHOR]

AlTiN coatings with a NaCl structure have onset point of oxidation around 850 °C. To withstand oxidation above 850 °C, we studied the influence of Cr addition on the structure, mechanical properties and oxidation resistance of different AlTiCrN coatings. The structural evolution during the annealing of the AlTiCrN coating was revealing that all coatings kept the NaCl structure up to 950 °C. The oxidized coatings shown that the addition of Cr promoted the formation of a TiO 2 layer over a gradient CrAl 2 O 3 layer. This last layer is very rich in aluminum under the TiO 2 layer and richer in chromium at the nitride-oxide interphase. [Display omitted] • Al 0.45 Ti 0.29 Cr 0.26 N coating kept the single-phase cubic structure up to 950 °C. • Cr content can stabilize the hardness and the elastic modulus independently of the Al/Ti ratio in the as-deposited coating. • The addition of Cr to AlTiN coating promoted the formation of a TiO 2 layer over a gradient (Cr x Al y) 2 O 3 layer at 950 °C. • The oxidation mechanism is controlled by the cationic diffusion of oxygen to the oxide-nitride coating interface and by the anionic grain-boundary diffusion of titanium at the external surface. [ABSTRACT FROM AUTHOR]

By analyzing the angular correlations in scanning electron nanodiffraction patterns from a melt-spun Zr36Cu64 glass, the dominant local order was identified as icosahedral clusters. Mapping the extent of this icosahedral short-range order demonstrates that the medium-range order in this material is consistent with a face-sharing or interpenetrating configuration. These conclusions support results from atomistic modeling and a structural basis for the glass formability of this system. [ABSTRACT FROM AUTHOR]

Abstract: We have developed a new oral vaccine against enterotoxigenic Escherichia coli (ETEC) diarrhea containing killed recombinant E. coli bacteria expressing increased levels of ETEC colonization factors (CFs) and a recombinant protein (LCTBA), i.e. a hybrid between the binding subunits of E. coli heat labile toxin (LTB) and cholera toxin (CTB). We describe a randomized, comparator controlled, double-blind phase I trial in 60 adult Swedish volunteers of a prototype of this vaccine. The safety and immunogenicity of the prototype vaccine, containing LCTBA and an E. coli strain overexpressing the colonization factor CFA/I, was compared to a previously developed oral ETEC vaccine, consisting of CTB and inactivated wild type ETEC bacteria expressing CFA/I (reference vaccine). Groups of volunteers were given two oral doses of either the prototype or the reference vaccine; the prototype vaccine was administered at the same or a fourfold higher dosage than the reference vaccine. The prototype vaccine was found to be safe and equally well-tolerated as the reference vaccine at either dosage tested. The prototype vaccine induced mucosal IgA (fecal secretory IgA and intestine-derived IgA antibody secreting cell) responses to both LTB and CFA/I, as well as serum IgA and IgG antibody responses to LTB. Immunization with LCTBA resulted in about twofold higher mucosal and systemic IgA responses against LTB than a comparable dose of CTB. The higher dose of the prototype vaccine induced significantly higher fecal and systemic IgA responses to LTB and fecal IgA responses to CFA/I than the reference vaccine. These results demonstrate that CF over-expression and inclusion of the LCTBA hybrid protein in an oral inactivated ETEC vaccine does not change the safety profile when compared to a previous generation of such a vaccine and that the prototype vaccine induces significant dose dependent mucosal immune responses against CFA/I and LTB. [Copyright &y& Elsevier]

The article discusses the spread of cholera in Africa. Statistics are reported for cases and outbreaks recorded since 1995 in the Democratic Republic of the Congo, DRC. The article notes that cholera is spreading to South Africa, Mozambique, and other neighboring countries. It notes involvement of the United Nations and the World Health Organization and cholera treatment using oral rehydration solution (ORS). It discusses issues associated with vaccine use.

Novel BN tassel-like and tree-like nanostructures were synthesized through a CVD method. The tassel-like morphology is made up of a BN bamboo-shaped nanotube and numerous polyhedral particles attached onto it. The tree consists of a BN main stem and many BN nanotube branches growing outward from it. The attachments, either particles or nanotube branches, maintain adhering to the primary stems even after 15 min sonication treatment, indicating the high stability of these nanostructures. The formation of these unusual structures is proposed to arise from a two-stage deposition process: firstly, primary BN stems were formed, followed by subsequent precipitation of amorphous clusters onto the rough outer surfaces. Secondly, polyhedral particles or BN nanotubes nucleated and grew on the outer surface as a result of further deposition from the vapor phase. [Copyright &y& Elsevier]

TiAlN single layer coatings deposited by High-Power Impulse Magnetron Sputtering (HiPIMS) on carbide and Si-wafers substrates were performed. They were characterized in order to study the effects of different process parameters on the film stoichiometry, microstructure and morphology and finally their mechanical and tribological properties were investigated. For comparison, the properties of the same composition Ti 50 Al 50 N coatings produced by Cathodic Arc Evaporation (CAE) were also studied. Only the most influential process parameters, which are the effects of duty cycle, pressure, power and bias for the HiPIMS process are here discussed. High-resolution TEM images were used to investigate the microstructure of CAE and HiPIMS coatings and the observations indicate that both processes produced high density Ti 50 Al 50 N coatings with a fine fibrous structure, and a similar grain size. XRD analyses showed that TiAlN coatings deposited by CAE and by HiPIMS have a single-phase cubic structure with respectively the (200) and (111) reflection peaks as a preferred orientation. Furthermore, the residual stresses determined by XRD for the HiPIMS coated samples show that it can be possible to tune them from tensile (+500 MPa) to high compressive stresses (−4000 MPa) by adjusting the process parameters. Independently of their intrinsic stress level, the HiPIMS coatings show similar hardness and the values obtained are in the same range of CAE coatings (30–35 GPa) with same composition and thickness. However, during ball-on-disc tests in dry condition using a steel ball against the coated carbide substrate, the behaviour of similar Ti 50 Al 50 N as deposited coatings produced by these two processes was different. Lower friction coefficients (−30%) but, higher abrasion kinetic of the steel ball as counterpart during pin-on-disk test (+50%) were recorded for the Ti 50 Al 50 N HiPIMS coatings. In conclusion, it is proposed that, for HiPIMS coatings with high compressive stresses (<−5000 MPa), having also low surface roughness and (111) main texture orientation, high tribological properties can be achieved. • Comparison between the Ti 50 Al 50 N thin film coating produced by HiPIMS and CAE. • Influence of HiPIMS process parameters on the micro-mechanical properties of the Ti 50 Al 50 N coatings. • Hardness, E-modulus and Wear resistance of Ti 50 Al 50 N-HiPIMS by comparison with CAE. • High performances of Ti 50 Al 50 N coatings synthesized by HiPIMS during a ball-on-disc test by comparison with CAE coatings. [ABSTRACT FROM AUTHOR]

The following features of multiwalled BN nanotubes were discovered using a field emission high-resolution analytical transmission electron microscope: (i) coexistence of hexagonal and rhombohedral stacking in nanotube shell assembly; (ii) flattening of nanotube cross section, which makes possible clear atomic resolution of the core structure in a three-shelled nanotube; and (iii) change in chirality of tubular layers from armchair to zigzag arrangement in a 30° double-walled nanotube kink, as revealed by atomically resolved images of tube wall segments. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]