Measurement of Water Uptake and States in Nafion Membranes Using Humidity-Controlled Terahertz Time-Domain Spectroscopy.

Perfluorinated sulfonic acid ionomers are well known for their unique water uptake properties and chemical/mechanical stability. Understanding their performance-stability trade-offs is key to realizing membranes with optimal properties. Terahertz time-domain spectroscopy has been demonstrated to resolve water states inside industrially relevant membranes, producing qualitatively agreeable results to conventional gravimetric analysis and prior demonstrations.

Surface Analysis of Pristine and Cycled NMC/Graphite Lithium-Ion Battery Electrodes: Addressing the Measurement Challenges.

Lithium-ion batteries are the most ubiquitous energy storage devices in our everyday lives. However, their energy storage capacity fades over time due to chemical and structural changes in their components, via different degradation mechanisms. Understanding and mitigating these degradation mechanisms is key to reducing capacity fade, thereby enabling improvement in the performance and lifetime of Li-ion batteries, supporting the energy transition to renewables and electrification.

Femtosecond pulse laser cleaning of spray paint from heritage stone surfaces.

We explore the use of femtosecond laser pulses to clean a variety of colors of spray paint from the Moruya granite, a stone with high heritage value that is widely used for monuments and sculptures in Sydney and New South Wales (Australia). The efficiency of the cleaning treatment and the effects on the stone substrate are evaluated using optical microscopy, optical profilometry, Raman spectroscopy, energy-dispersive X-ray spectroscopy, and colorimetry. We demonstrate that femtosecond laser cleans granite without damaging it and without discoloration when the laser fluence is set below the damage threshold of the stone.

Third international challenge to model the medium- to long-range transport of radioxenon to four Comprehensive Nuclear-Test-Ban Treaty monitoring stations.

In 2015 and 2016, atmospheric transport modeling challenges were conducted in the context of the Comprehensive Nuclear-Test-Ban Treaty (CTBT) verification, however, with a more limited scope with respect to emission inventories, simulation period and number of relevant samples (i.e., those above the Minimum Detectable Concentration (MDC)) involved.

A universal polymer shell-isolated nanoparticle (SHIN) design for single particle spectro-electrochemical SERS sensing using different core shapes.

Shell-isolated nanoparticles (SHINs) have attracted increasing interest for non-interfering plasmonic enhanced sensing in fields such as materials science, biosensing, and in various electrochemical systems. The metallic core of these nanoparticles is isolated from the surrounding environment preventing direct contact or chemical interaction with the metal surface, while still being close enough to enable localized surface plasmon enhancement of the Raman scattering signal from the analyte. This concept forms the basis of the shell isolated nanoparticle-enhanced Raman spectroscopy (SHINERS) technique.

Atmospheric modelling of grass pollen rupturing mechanisms for thunderstorm asthma prediction.

The world's most severe thunderstorm asthma event occurred in Melbourne, Australia on 21 November 2016, coinciding with the peak of the grass pollen season. The aetiological role of thunderstorms in these events is thought to cause pollen to rupture in high humidity conditions, releasing large numbers of sub-pollen particles (SPPs) with sizes very easily inhaled deep into the lungs. The humidity hypothesis was implemented into a three-dimensional atmospheric model and driven by inputs from three meteorological models.

Electrocatalytic Behavior of PtCu Clusters Produced by Nanoparticle Beam Deposition.

State-of-the-art electrocatalysts for electrolyzer and fuel cell applications currently rely on platinum group metals, which are costly and subject to supply risks. In recent years, a vast collection of research has explored the possibility of reducing the Pt content in such catalysts by alloying with earth-abundant and cheap metals, enabling co-optimization of cost and activity. Here, using nanoparticle beam deposition, we explore the electrocatalytic performance of PtCu alloy clusters in the hydrogen evolution reaction (HER).

Observation of Substituent Effects in the Electrochemical Adsorption and Hydrogenation of Alkynes on Pt{} Using SHINERS.

By combining cyclic voltammetry (CV) and shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS), the adsorption behavior of two alkynes, propargyl alcohol (PA) and 2-methyl-3-butyn-2-ol (MeByOH), undergoing hydrogenation on Pt basal plane single-crystal electrodes is investigated. It is found that PA and MeByOH give rise to strong surface sensitivities in relation to both hydrogenation activity and molecular fragmentation into adsorbed species such as CO. For PA, irreversible adsorption is strongly favored for Pt{100} and Pt{110} but is weak in the case of Pt{111}.

The Role of Tungsten Oxide in Enhancing the Carbon Monoxide Tolerance of Platinum-Based Hydrogen Oxidation Catalysts.

Significant reductions in total cost of ownership can be realized by engineering PEM fuel cells to run on low-purity hydrogen. One of the main drawbacks of low-purity hydrogen fuels is the carbon monoxide fraction, which poisons platinum electrocatalysts and reduces the power output below useful levels. Platinum-tungsten oxide catalyst systems have previously shown high levels of CO tolerance during both ex situ and in situ investigations.

Active site manipulation in MoS cluster electrocatalysts by transition metal doping.

The development of non-platinum group metal catalysts for the hydrogen evolution reaction (HER) in water electrolyser devices is essential for their widespread and sustainable deployment. In recent years, molybdenum disulfide (MoS2) catalysts have received significant attention as they not only exhibit good electrocatalytic HER activity but also, crucially, acid-stability. However, further performance enhancement is required for these materials to be competitive with Pt and to that end transition metal doping of MoS2 has been explored as a route to further increasing its catalytic activity.

Curated Collections for Clinician Educators: Five Key Papers on Graduated Responsibility in Residency Education.

Introduction The Accreditation Council for Graduate Medical Education calls graduated responsibility "one of the core tenets of American graduate medical education." However, there is no clear set of resources for programs to implement a system of progressively increasing responsibilities for trainees. This project aimed to identify a set of high-yield papers on graduated responsibility for junior faculty members.

Nanoscale Chemical Imaging of a Single Catalyst Particle with Tip-Enhanced Fluorescence Microscopy.

Determining the active site in real-life solid catalysts remains an intellectual challenge and is crucial for exploring the road towards their rational design. In recent years various micro-spectroscopic methods have revealed valuable structure-activity data at the level of a single catalyst particle, even under reaction conditions. Herein, we introduce Tip-Enhanced FLuorescence (TEFL) microscopy as a novel and versatile characterization tool for catalysis research.

In Situ Nanoscale Investigation of Catalytic Reactions in the Liquid Phase Using Zirconia-Protected Tip-Enhanced Raman Spectroscopy Probes.

Tip-enhanced Raman spectroscopy (TERS) is a promising technique that enables nondestructive and label-free topographical and chemical imaging at the nanoscale. However, its scope for in situ characterization of catalytic reactions in the liquid phase has remained limited due to the lack of durable and chemically inert plasmonically active TERS probes. Herein, we present novel zirconia-protected TERS probes with 3 orders of magnitude increase in lifetime under ambient conditions compared to unprotected silver-coated probes, together with high stability in liquid media.

Nanoscale chemical imaging using tip-enhanced Raman spectroscopy.

Confocal and surface-enhanced Raman spectroscopy (SERS) are powerful techniques for molecular characterization; however, they suffer from the drawback of diffraction-limited spatial resolution. Tip-enhanced Raman spectroscopy (TERS) overcomes this limitation and provides chemical information at length scales in the tens of nanometers. In contrast to alternative approaches to nanoscale chemical analysis, TERS is label free, is non-destructive, and can be performed in both air and liquid environments, allowing its use in a diverse range of applications.

Mechanism of Gold-Assisted Exfoliation of Centimeter-Sized Transition-Metal Dichalcogenide Monolayers.

Exfoliation of large-area monolayers is important for fundamental research and technological implementation of transition-metal dichalcogenides. Various techniques have been explored to increase the exfoliation yield, but little is known about the underlying mechanism at the atomic level. Here, we demonstrate gold-assisted mechanical exfoliation of monolayer molybdenum disulfide, up to a centimeter scale.

Nanoscale chemical imaging of solid-liquid interfaces using tip-enhanced Raman spectroscopy.

Tip-enhanced Raman spectroscopy (TERS) is a powerful tool for non-destructive and label-free surface molecular mapping at the nanoscale. However, to date nanoscale resolution chemical imaging in a liquid environment has not been possible, in part due to the lack of robust TERS probes that are stable when immersed in a liquid. In this work, we have addressed this challenge by developing plasmonically-active TERS probes with a multilayer metal coating structure that can be successfully used within a liquid environment.

Extending the plasmonic lifetime of tip-enhanced Raman spectroscopy probes.

Tip-enhanced Raman spectroscopy (TERS) is an emerging technique for simultaneous mapping of chemical composition and topography of a surface at the nanoscale. However, rapid degradation of TERS probes, especially those coated with silver, is a major bottleneck to the widespread uptake of this technique and severely prohibits the success of many TERS experiments. In this work, we carry out a systematic time-series study of the plasmonic degradation of Ag-coated TERS probes under different environmental conditions and demonstrate that a low oxygen (<1 ppm) and a low moisture (<1 ppm) environment can significantly improve the plasmonic lifetime of TERS probes from a few hours to a few months.

Sensitivity, specificity and diagnostic accuracy of novices integrating lung ultrasound into the care of breathless older patients.

Lung ultrasound is frequently used to identify pulmonary oedema, using the 'B line' artefact. A small study in 2011 suggested that novice sonologists had a potential diagnostic accuracy of 85%, when performing the test without reference to other patient information. We aimed to test the overall diagnostic accuracy of novice clinician sonologists incorporating the 2011 protocol into routine assessment of the patient.

Intrinsically Microporous Polymer Retains Porosity in Vacuum Thermolysis to Electroactive Heterocarbon.

Vacuum carbonization of organic precursors usually causes considerable structural damage and collapse of morphological features. However, for a polymer with intrinsic microporosity (PIM-EA-TB with a Brunauer-Emmet-Teller (BET) surface area of 1027 m(2)g(-1)), it is shown here that the rigidity of the molecular backbone is retained even during 500 °C vacuum carbonization, yielding a novel type of microporous heterocarbon (either as powder or as thin film membrane) with properties between those of a conducting polymer and those of a carbon. After carbonization, the scanning electron microscopy (SEM) morphology and the small-angle X-ray scattering (SAXS) Guinier radius remain largely unchanged as does the cumulative pore volume.

Electrochemical imaging of hydrogen peroxide generation at individual gold nanoparticles.

Localised hydrogen peroxide generation at individual catalytic gold nanoparticles within ensemble electrodes is mapped for the first time using combined scanning electrochemical-scanning ion conductance microscopy (SECM-SICM).

Nanoscale mapping of catalytic activity using tip-enhanced Raman spectroscopy.

Chemical mapping of a photocatalytic reaction with nanoscale spatial resolution is demonstrated for the first time using tip-enhanced Raman spectroscopy (TERS). An ultrathin alumina film applied to the Ag-coated TERS tip blocks catalytic interference whilst maintaining near-field electromagnetic enhancement, thus enabling spectroscopic imaging of catalytic activity on nanostructured Ag surfaces.

Treating the untreatable in art and heritage materials: ultrafast laser cleaning of "cloth-of-gold".

Laser cleaning provides art and heritage conservators with an alternative means to restore objects when traditional chemical and mechanical methods are not viable. However, long (>nanosecond) laser pulses can cause unwanted damage from photothermal processes and provide limited control over ablation depth. Ultrashort ( View Article and Find Full Text PDF

Mapping electroactivity at individual catalytic nanostructures using high-resolution scanning electrochemical-scanning ion conductance microcopy.

Combined scanning electrochemical-scanning ion conductance microcopy (SECM-SICM) has been used to map the electroactivity of surfaces decorated with individual features at the 100-150 nm scale. Dual channel capillary probes consisting of an open SICM barrel, and a solid carbon SECM electrode enabled correlation of surface activity with accurate topographical information. Measurements were validated by approach curve analysis and imaging of model systems in feedback and substrate generation-tip collection modes and then applied to the examination of two nanostructured test substrates.