Local Built-In Field at the Sub-nanometric Heterointerface Mediates Cascade Electrochemical Conversion of Lithium-sulfur Batteries.

Heterogeneous catalytic mediators have been proposed to play a vital role in enhancing the multiorder reaction and nucleation kinetics in multielectron sulfur electrochemistry. However, the predictive design of heterogeneous catalysts is still challenging, owing to the lack of in-depth understanding of interfacial electronic states and electron transfer on cascade reaction in Li-S batteries. Here, a heterogeneous catalytic mediator based on monodispersed titanium carbide sub-nanoclusters embedded in titanium dioxide nanobelts is reported. The tunable catalytic and anchoring effects of the resulting catalyst are achieved by the redistribution of localized electrons caused by the abundant built-in fields in heterointerfaces. Subsequently, the resulting sulfur cathodes deliver an areal capacity of 5.6 mAh cm-2 and excellent stability at 1 C under sulfur loading of 8.0 mg cm-2 . The catalytic mechanism especially on enhancing the multiorder reaction kinetic of polysulfides is further demonstrated via operando time-resolved Raman spectroscopy during the reduction process in conjunction with theoretical analysis.

Low-energy scanning transmission electron microscopy applied to ice-embedded biological macromolecules.

In this report, we applied annular bright-field and annular dark-field low-energy (30 keV) scanning transmission electron microscopy imaging to a vitreous ice-embedded biological macromolecule, T4 phage, to investigate the applicability of these methods for morphological investigation and sample screening. Multiple camera lengths were examined to find the optimal acceptance angle for both modes. Image clarity differed substantially between the modes, with the presence of ice also strongly influencing the quality of acquired micrographs. In annular dark-field mode, the proper discrimination of electrons scattered by the specimen from those scattered by the background ice was found to be difficult due to the severe overlap of the scattered electrons. The resulting micrographs lacked clarity, and the ice-embedded phage particles could only be discerned after post-processing image adjustment. However, in annular bright-field mode, despite similar overlapping of the scattered electrons, it was possible to assess the morphology and intactness of the specimen in the embedding ice, suggesting that this mode may find utility in low-energy cryo-scanning transmission electron microscopy imaging methods.

Interpretation of mean free path values derived from off-axis electron holography amplitude measurements.

In this work, we have explored the factors which govern mean free path values obtained from off-axis electron holography measurements. Firstly, we explore the topic from a theoretical perspective, and show that the mean amplitude reconstructed from off-axis holograms is due to the coherent portion of the direct, central object-transmitted beam only - it is not affected by the presence or absence of other scattered beams. Secondly, we present a detailed experimental study which compares mean free path values obtained from hologram sideband, centreband, EELS, and TEM measurements as a function of optical collection angle and energy-loss-filtering. These results confirm that the coherent portion of the direct beam defines the mean amplitude, and additionally show that the coherent portion corresponds to the conventional energy-filtered signal (with threshold 5 eV in this work). Finally, we present summary measurements from a selection of different materials, and compare the results against a simple electron scattering model. This study reinforces the claim that the mean amplitude is defined by the energy-filtered direct beam, and confirms that the contributions of elastic and inelastic scattering to the total mean free path are broadly in line with theoretical expectations for these different materials. These results in aggregate indicate that neither experimental collection angles nor enhanced sensitivity to low-loss phonon scattering affect the mean amplitude signal arising from off-axis holography reconstructions, nor the associated mean free path values which are derived from this mean amplitude.

Bragg holography of nano-crystals.

Crystal diffraction is a well-established technique for high-resolution structural analysis of material science and biological samples. However, the recovered structure is a result of averaging over all the unit cells in the crystal, which smears out the imperfections, atomic defects, or asymmetries and chiral properties of the individual molecules. We propose Bragg holography, where a nano-crystal is imaged at a defocus distance allowing separation of the diffracted beams, without turning them into peaks. The presence of a reference wave gives rise to a Bragg hologram, which can be reconstructed by conventional holographic reconstruction algorithms. The recovered complex-valued wavefront contains the complete information about the atomic distribution in the crystal, including defects. Bragg holography is demonstrated for gold nano-crystals, and its feasibility for biological nano-crystals is shown.

New Zealand community mental healthcare provider experience in schizophrenia management with 3-monthly paliperidone palmitate.

OBJECTIVES: To understand the impact of 3-monthly treatment with paliperidone palmitate on patient management, including non-adherence and relapse, from a psychiatrist and nurse perspective for 73 patients enrolled in a patient familiarisation programme (PFP) in New Zealand. METHODS: An online questionnaire was sent to clinicians with at least 6 months of regular interaction with PFP patients. Questions addressed treatment effectiveness and patient management changes. Analyses are descriptive only and do not represent patient or carer perspectives. RESULTS: Seven psychiatrists, representing 58 of 73 (79.5%) of patients, and 17 nurses responded to the survey. Psychiatrists were satisfied with efficacy and tolerability and relapse prevention. Treatment goals were either 'met' (2/7; 28.6%) or 'exceeded' (5/7; 71.4%). The focus on adherence issues decreased and the focus on life areas and recovery goals increased. CONCLUSIONS: From the clinician perspective, 3-monthly paliperidone palmitate offers patients the potential to remain adherent and improve social functioning.

Low-energy in-line electron holographic imaging of vitreous ice-embedded small biomolecules using a modified scanning electron microscope.

Cryo-electron microscopy (cryo-EM) has become the method of choice in the field of structural biology, owing to its unique ability to deduce structures of vitreous ice-embedded, hydrated biomolecules over a wide range of structural resolutions. As cryo-transmission electron microscopes (cryo-TEM) become increasingly specialised for high, near-atomic resolution studies, operational complexity and associated costs serve as significant barriers to widespread usability and adoptability. To facilitate the expansion and accessibility of the cryo-EM method, an efficient, user-friendly means of imaging vitreous ice-embedded biomolecules has been called for. In this study, we present a solution to this issue by integrating cryo-EM capabilities into a commercial scanning electron microscope (SEM). Utilising the principle of low-energy in-line electron holography, our newly developed hybrid microscope permits low-to-moderate resolution imaging of vitreous ice-embedded biomolecules without the need for any form of sample staining or chemical fixation. Operating at 20 kV, the microscope takes advantage of the ease-of-use of SEM-based imaging and phase contrast imaging of low-energy electron holography. This study represents the first reported successful application of low-energy in-line electron holographic imaging to vitreous ice-embedded small biomolecules, the effectiveness of which is demonstrated here with three morphologically distinct specimens.

Improved sample dispersion in cryo-EM using "perpetually-hydrated" graphene oxide flakes.

For many macromolecular complexes, the inability to uniformly disperse solubilized specimen particles within vitreous ice films precludes their analysis by cryo-electron microscopy (cryo-EM). Here, we introduce a sample preparation process using "perpetually-hydrated" graphene oxide flakes as particle support films, and report vastly improved specimen dispersion. The new method introduced in this study incorporates hydrated graphene oxide flakes into a standard sample preparation regime, without the need for additional tools or devices, making it a cost-effective and easily adoptable alternative to currently available sample preparation approaches.

Improved sample dispersion in cryo-EM using "perpetually-hydrated" graphene oxide flakes.

For many macromolecular complexes, the inability to uniformly disperse solubilized specimen particles within vitreous ice films precludes their analysis by cryo-electron microscopy (cryo-EM). Here, we introduce a sample preparation process using "perpetually-hydrated" graphene oxide flakes as particle support films, and report vastly improved specimen dispersion. Furthermore, we provide evidence that the presence of graphene oxide flakes in vitreous ice results in a significant reduction in electron beam-induced specimen decomposition. The new method introduced in this study incorporates hydrated graphene oxide flakes into a standard sample preparation regime, without the need for additional tools or devices, making it a cost-effective and easily adoptable alternative to currently available sample preparation approaches.

Development of a SEM-based low-energy in-line electron holography microscope for individual particle imaging.

A new SEM-based in-line electron holography microscope has been under development. The microscope utilizes conventional SEM and BF-STEM functionality to allow for rapid searching of the specimen of interest, seamless interchange between SEM, BF-STEM and holographic imaging modes, and makes use of coherent low-energy in-line electron holography to obtain low-dose, high-contrast images of light element materials. We report here an overview of the instrumentation and first experimental results on gold nano-particles and carbon nano-fibers for system performance tests. Reconstructed images obtained from the holographic imaging mode of the new microscope show substantial image contrast and resolution compared to those acquired by SEM and BF-STEM modes, demonstrating the feasibility of high-contrast imaging via low-energy in-line electron holography. The prospect of utilizing the new microscope to image purified biological specimens at the individual particle level is discussed and electron optical issues and challenges to further improve resolution and contrast are considered.

The Precompetition Macronutrient Intake of Elite Gaelic Football Players.

Competition-related dietary intake has not yet been investigated in Gaelic football. The present study examined the precompetition macronutrient intake of elite male Gaelic football players. Forty players from two teams completed a food diary on the 2 days preceding competition (Day 1 and Day 2) and on the match day prior to the match (match day). Carbohydrate intake was significantly greater on Day 2 compared with Day 1, for both absolute (295 ± 98 vs. 318 ± 77 g; p = .048; -23.6 g, 95% confidence interval [-47.3, 0.2]; Cohen's d = 0.27) and relative intake (3.4 ± 1.1 vs. 3.7 ± 1.0 g/kg; p = .027; -0.3 g/kg, 95% confidence interval [-0.6, -0.03]; Cohen's d = 0.32). The number of players in accordance with and not in accordance with the guidelines for carbohydrate intake on Day 2 was significantly different to an expected frequency distribution, χ2(1) = 32.400; p ≤ .001; φ = 0.9, with a greater number of players not meeting the guidelines (observed N = 2 vs. 38). The number of players in accordance with and not in accordance with the recommendations for carbohydrate intake on match day was significantly different to an expected frequency distribution, χ2(1) = 8.100; p = .004; φ = 0.45, with a greater number of players meeting the guidelines (observed N = 29 vs. 11). The major finding from the current investigation was that a significantly greater number of players did not meet carbohydrate intake guidelines on the day before competition. Individualized nutritional interventions are required in order to modify the current prematch dietary intake.

Water without windows: Evaluating the performance of open cell transmission electron microscopy under saturated water vapor conditions, and assessing its potential for microscopy of hydrated biological specimens.

We have performed open cell transmission electron microscopy experiments through pure water vapor in the saturation pressure regime (>0.6 kPa), in a modern microscope capable of sub-Å resolution. We have systematically studied achievable pressure levels, stability and gas purity, effective thickness of the water vapor column and associated electron scattering processes, and the effect of gas pressure on electron optical resolution and image contrast. For example, for 1.3 kPa pure water vapor and 300kV electrons, we report pressure stability of ± 20 Pa over tens of minutes, effective thickness of 0.57 inelastic mean free paths, lattice resolution of 0.14 nm on a reference Au specimen, and no significant degradation in contrast or stability of a biological specimen (M13 virus, with 6 nm body diameter). We have also done some brief experiments to confirm feasibility of loading specimens into an in situ water vapor ambient without exposure to intermediate desiccating conditions. Finally, we have also checked if water experiments had any discernible impact on the microscope performance, and report pertinent vacuum and electron optical data, for reference purposes.

Engineering high-performance Pd core-MgO porous shell nanocatalysts via heterogeneous gas-phase synthesis.

We report on the design and synthesis of high performance catalytic nanoparticles with a robust geometry via magnetron-sputter inert-gas condensation. Sputtering of Pd and Mg from two independent neighbouring targets enabled heterogeneous condensation and growth of nanoparticles with controlled Pd core-MgO porous shell structure. The thickness of the shell and the number of cores within each nanoparticle could be tailored by adjusting the respective sputtering powers. The nanoparticles were directly deposited on glassy carbon electrodes, and their catalytic activity towards methanol oxidation was examined by cyclic voltammetry. The measurements indicated that the catalytic activity was superior to conventional bare Pd nanoparticles. As confirmed by electron microscopy imaging and supported by density-functional theory (DFT) calculations, we attribute the improved catalytic performance primarily to inhibition of Pd core sintering during the catalytic process by the metal-oxide shell.

Single CuO nanowires decorated with size-selected Pd nanoparticles for CO sensing in humid atmosphere.

We report on conductometric gas sensors based on single CuO nanowires and compare the carbon monoxide (CO) sensing properties of pristine as well as Pd nanoparticle decorated devices in humid atmosphere. Magnetron sputter inert gas aggregation combined with a quadrupole mass filter for cluster size selection was used for single-step Pd nanoparticle deposition in the soft landing regime. Uniformly dispersed, crystalline Pd nanoparticles with size-selected diameters around 5 nm were deposited on single CuO nanowire devices in a four point configuration. During gas sensing experiments in humid synthetic air, significantly enhanced CO response for CuO nanowires decorated with Pd nanoparticles was observed, which validates that magnetron sputter gas aggregation is very well suited for the realization of nanoparticle-functionalized sensors with improved performance.

Smart composite nanosheets with adaptive optical properties.

We report efficient design and facile synthesis of size-tunable organic/inorganic nanosheets, via a straightforward liquid exfoliation-adsorption process, of a near percolating gold (Au) thin film deposited onto a branched polyethylenimine (bPEI) matrix. The nanosheets are stiff enough to sustain their two-dimensional (2D) nature in acidic conditions, yet flexible enough to undergo a perfect reversible shape transformation to 1D nanoscrolls in alkaline conditions. The shape transformations, and associated optical property changes, at different protonation states are monitored by transmission electron microscopy (TEM), atomic force microscopy (AFM), UV-visible spectroscopy and zeta potential measurements. Because of their large surface area, both nanosheets and nanoscrolls could be used as capturing substrates for surface-enhanced Raman scattering (SERS) applications.

Coalescence-induced crystallisation wave in Pd nanoparticles.

Palladium nanoparticles offer an attractive alternative to bulk palladium for catalysis, hydrogen storage and gas sensing applications. Their performance depends strongly on surface structure; therefore, nanoparticle coalescence can play an important role, as it determines the resultant structure of the active sites where reactions (e.g. catalysis) actually take place, i.e. facets, edges, vertices or protrusions. With this in mind, we performed classical molecular dynamics (MD) simulations and magnetron-sputtering inert gas condensation depositions of palladium nanoparticles, supported by high-resolution transmission electron microscopy (HRTEM), to study the mechanisms that govern their coalescence. Surface energy minimisation drove the interactions initially, leading to the formation of an interface/neck, as expected. Intriguingly, at a later stage, atomic rearrangements triggered a crystallisation wave propagating through the amorphous nanoparticles, leading to mono- or polycrystalline fcc structures. In the case of crystalline nanoparticles, almost-epitaxial alignment occurred and the formation of twins and surface protrusions were observed.

Inoculation of silicon nanoparticles with silver atoms.

Silicon (Si) nanoparticles were coated inflight with silver (Ag) atoms using a novel method to prepare multicomponent heterostructured metal-semiconductor nanoparticles. Molecular dynamics (MD) computer simulations were employed, supported by high-resolution bright field (BF) transmission electron microscopy (HRTEM) and aberration-corrected scanning transmission electron microscopy (STEM) with a resolution ≤0.1 nm in high angle annular dark field (HAADF) mode. These studies revealed that the alloying behavior and phase dynamics during the coating process are more complex than when attaching hetero-atoms to preformed nanoparticles. According to the MD simulations, Ag atoms condense, nucleate and diffuse into the liquid Si nanoparticles in a process that we term "inoculation", and a phase transition begins. Subsequent solidification involves an intermediate alloying stage that enabled us to control the microstructure and crystallinity of the solidified hybrid heterostructured nanoparticles.