Neural network enabled nanoplasmonic hydrogen sensors with 100 ppm limit of detection in humid air

Environmental humidity variations are ubiquitous and high humidity characterizes fuel cell and electrolyzer operation conditions. Since hydrogen-air mixtures are highly flammable, humidity tolerant H2 sensors are important from safety and process monitoring perspectives. Here, we report an optical nanoplasmonic hydrogen sensor operated at elevated temperature that combined with Deep Dense Neural Network or Transformer data treatment involving the entire spectral response of the sensor enables a 100 ppm H2 limit of detection in synthetic air at 80% relative humidity. This significantly exceeds the <1000 ppm US Department of Energy performance target. Furthermore, the sensors pass the ISO 26142:2010 stability requirement in 80% relative humidity in air down to 0.06% H2 and show no signs of performance loss after 140 h continuous operation. Our results thus demonstrate the potential of plasmonic hydrogen sensors for use in high humidity and how neural-network-based data treatment can significantly boost their performance.

Performance of an innovative culture-based digital dipstick for detection of bacteriuria

IMPORTANCE

In this study, we explore the transformative potential of UTI-lizer, an emerging technology not yet commercially available. Our manuscript shows that UTI-lizer is a promising alternative for detecting the five main pathogens that cause urinary tract infections (UTIs). The results also indicate that digital dipsticks have the potential to uniquely provide UTI diagnostic quality on par with that of gold-standard testing, with the added benefits of ease of testing, rapid test handling time, and simple test equipment. This technology can be helpful in quickly ruling out bacterial infections and reducing the unnecessary use of antibiotics, especially in primary care settings or at the point of care. Moreover, the UTI-lizer test can reduce the number of negative urine samples sent to central laboratories, thus easing the burden of UTI diagnostics on the healthcare system. We believe our study, as well as current and upcoming research based on this technology, is highly relevant for clinical microbiologists, microbiology scientists, general practitioners, and urologists.

Psychometric evaluation of the electronic faces thermometer scale for pain assessment in children 8-17 years old: A study protocol

It is often a challenge for a child to communicate their pain, and their possibilities to do so should be strengthened in healthcare settings. Digital self-assessment provides a potential solution for person-centered care in pain management and promotes child participation when a child is ill. A child's perception of pain assessment differs when it is assessed using digital or analog formats. As we move into the digital era, there is an urgent need to validate digital pain assessment tools, including the newly developed electronic Faces Thermometer Scale (eFTS). This study protocol describes three studies with the overall aim to evaluate psychometric properties of the eFTS for assessing pain in children 8-17 years of age. A multi-site project design combining quantitative and qualitative methods will be used for three observational studies. Study 1: 100 Swedish-speaking children will report the level of anticipated pain from vignettes describing painful situations in four levels of pain and a think-aloud method will be used for data collection. Data will be analyzed with phenomenography as well as descriptive and comparative statistics. Study 2: 600 children aged 8-17 years at pediatric and dental settings in Sweden, Denmark, Iceland, and USA will be included. Children will assess their pain intensity due to medical or dental procedures, surgery, or acute pain using three different pain Scales for each time point; the eFTS, the Faces Pain Scale Revised, and the Coloured Analogue Scale. Descriptive and comparative statistics will be used, with subanalysis taking cultural context into consideration. Study 3: A subgroup of 20 children out of these 600 children will be purposely included in an interview to describe experiences of grading their own pain using the eFTS. Qualitative data will be analyzed with content analysis. Our pilot studies showed high level of adherence to the study procedure and rendered only a small revision of background questionnaires. Preliminary analysis indicated that the instruments are adequate to be used by children and that the analysis plan is feasible. A digital pain assessment tool contributes to an increase in pain assessment in pediatric care. The Medical Research Council framework for complex interventions in healthcare supports a thorough development of a new scale. By evaluating psychometric properties in several settings by both qualitative and quantitative methods, the eFTS will become a well-validated tool to strengthen the child's voice within healthcare.

Adolescents' experiences of Help Overcoming Pain Early-A school based person-centred intervention for adolescents with chronic pain

To illuminate adolescents' experiences of Help Overcoming Pain Early (HOPE), a person-centred intervention delivered in a school setting by school nurses. Twenty-one adolescents with chronic pain recruited from secondary school, who had completed the HOPE intervention, were included in the interview study. The HOPE intervention was built on person-centred ethics and consisted of four meetings between school nurses and adolescents on the subject of stress and pain management. A qualitative method using content analysis with an inductive approach was employed. In the interviews, the adolescents describe how they reclaim their lives with the help of HOPE. They use different strategies and parts of the intervention to move on with their lives. A trustful relationship, as that with the school nurse, was essential to dare to change. The overarching theme summarizes in Becoming myself again and is built up by three sub-themes: Trust a pillar for growth, Making sense of my life with pain, and Putting myself into the world again. A person-centred intervention such as HOPE applied in a school context is promising for promoting confidence in adolescents with chronic pain. A trust-building process emerged, in terms of both the adolescents' trust in the healthcare staff they meet and their confidence in their own ability to handle and influence their situation, which in the long term can promote trust in themselves as a person.

The Role of Grain Boundary Sites for the Oxidation of Copper Catalysts during the CO Oxidation Reaction

The oxidation of transition metal surfaces is a process that takes place readily at ambient conditions and that, depending on the specific catalytic reaction at hand, can either boost or hamper activity and selectivity. Cu catalysts are no exception in this respect since they exhibit different oxidation states for which contradicting activities have been reported, as, for example, in the catalytic oxidation of CO. Here, we investigate the impact of low-coordination sites on nanofabricated Cu nanoparticles with engineered grain boundaries on the oxidation of the Cu surface under CO oxidation reaction conditions. Combining multiplexed in situ single particle plasmonic nanoimaging, ex situ transmission electron microscopy imaging, and density functional theory calculations reveals a distinct dependence of particle oxidation rate on grain boundary density. Additionally, we found that the oxide predominantly nucleates at grain boundary-surface intersections, which leads to nonuniform oxide growth that suppresses Kirkendall-void formation. The oxide nucleation rate on Cu metal catalysts was revealed to be an interplay of surface coordination and CO oxidation behavior, with low coordination favoring Cu oxidation and high coordination favoring CO oxidation. These findings explain the observed single particle-specific onset of Cu oxidation as being the consequence of the individual particle grain structure and provide an explanation for widely distributed activity states of particles in catalyst bed ensembles.

Electron Beam Induced Enhancement and Suppression of Oxidation in Cu Nanoparticles in Environmental Scanning Transmission Electron Microscopy

We have investigated the effects of high-energy electron irradiation on the oxidation of copper nanoparticles in environmental scanning transmission electron microscopy (ESTEM). The hemispherically shaped particles were oxidized in 3 mbar of O2 in a temperature range 100-200 °C. The evolution of the particles was recorded with sub-nanometer spatial resolution in situ in ESTEM. The oxidation encompasses the formation of outer and inner oxide shells on the nanoparticles, arising from the concurrent diffusion of copper and oxygen out of and into the nanoparticles, respectively. Our results reveal that the electron beam actively influences the reaction and overall accelerates the oxidation of the nanoparticles when compared to particles oxidized without exposure to the electron beam. However, the extent of this electron beam-assisted acceleration of oxidation diminishes at higher temperatures. Moreover, we observe that while oxidation through the outward diffusion of Cu+ cations is enhanced, the electron beam appears to hinder oxidation through the inward diffusion of O2- anions. Our results suggest that the impact of the high-energy electrons in ESTEM oxidation of Cu nanoparticles is mostly related to kinetic energy transfer, charging, and ionization of the gas environment, and the beam can both enhance and suppress reaction rates.

Time-Resolved Thickness and Shape-Change Quantification using a Dual-Band Nanoplasmonic Ruler with Sub-Nanometer Resolution

Time-resolved measurements of changes in the size and shape of nanobiological objects and layers are crucial to understand their properties and optimize their performance. Optical sensing is particularly attractive with high throughput and sensitivity, and label-free operation. However, most state-of-the-art solutions require intricate modeling or multiparameter measurements to disentangle conformational or thickness changes of biomolecular layers from complex interfacial refractive index variations. Here, we present a dual-band nanoplasmonic ruler comprising mixed arrays of plasmonic nanoparticles with spectrally separated resonance peaks. As electrodynamic simulations and model experiments show, the ruler enables real-time simultaneous measurements of thickness and refractive index variations in uniform and heterogeneous layers with sub-nanometer resolution. Additionally, nanostructure shape changes can be tracked, as demonstrated by quantifying the degree of lipid vesicle deformation at the critical coverage prior to rupture and supported lipid bilayer formation. In a broader context, the presented nanofabrication approach constitutes a generic route for multimodal nanoplasmonic optical sensing.

Serum concentration trends and apparent half-lives of per- and polyfluoroalkyl substances (PFAS) in Australian firefighters

BACKGROUND

Per- and polyfluoroalkyl substances (PFASs) are persistent manmade compounds used in aqueous film forming foam (AFFF). The extensive use of AFFF has led to widespread environmental PFAS contamination and exposures of firefighters.

OBJECTIVES

To determine PFAS blood serum concentration trends and apparent serum half-lives in firefighters after the replacement of AFFF.

METHODS

Current and former employees of an Australian corporation providing firefighting services, where AFFF formulations had been used since the 1980s up until 2010, were recruited in 2018-2019 to participate in this study. Special focus was put on re-recruiting participants who had provided blood samples five years prior (2013-2014). Participants were asked to provide a blood sample and fill in a questionnaire. Serum samples were analysed for 40 different PFASs using HP LC-MS/MS.

RESULTS

A total of 799 participants provided blood samples in 2018-2019. Of these, 130 previously provided blood serum in 2013-2014. In 2018-2019, mean (arithmetic) serum concentrations of perfluorooctane sulfonate (PFOS, 27 ng/mL), perfluoroheptane sulfonate (PFHpS, 1.7 ng/mL) and perfluorohexane sulfonate (PFHxS, 14 ng/mL) were higher than the levels in the general Australian population. Serum concentrations were associated with the use of PFOS/PFHxS based AFFF. Participants who commenced service after the replacement of this foam had serum concentrations similar to those in the general population. Mean (arithmetic) individual apparent half-lives were estimated to be 5.0 years (perfluorooctanoic acid (PFOA)), 7.8 years (PFHxS), 7.4 years (PFHpS) and 6.5 years (PFOS).

CONCLUSION

This study shows how workplace interventions such as replacement of AFFF can benefit employees at risk of occupational exposure.

Health effects of reduced occupational sedentary behaviour in type 2 diabetes using a mobile health intervention: a study protocol for a 12-month randomized controlled trial-the ROSEBUD study

BACKGROUND

Short-term trials conducted in adults with type 2 diabetes mellitus (T2DM) showed that reducing sedentary behaviour by performing regular short bouts of light-intensity physical activity enhances health. Moreover, support for reducing sedentary behaviour may be provided at a low cost via mobile health technology (mHealth). There are a wide range of mHealth solutions available including SMS text message reminders and activity trackers that monitor the physical activity level and notify the user of prolonged sitting periods. The aim of this study is to evaluate the effects of a mHealth intervention on sedentary behaviour and physical activity and the associated changes in health in adults with T2DM.

METHODS

A dual-arm, 12-month, randomized controlled trial (RCT) will be conducted within a nationwide Swedish collaboration for diabetes research in primary health care. Individuals with T2DM (n = 142) and mainly sedentary work will be recruited across primary health care centres in five regions in Sweden. Participants will be randomized (1:1) into two groups. A mHealth intervention group who will receive an activity tracker wristband (Garmin Vivofit4), regular SMS text message reminders, and counselling with a diabetes specialist nurse, or a comparator group who will receive counselling with a diabetes specialist nurse only. The primary outcomes are device-measured total sitting time and total number of steps (activPAL3). The secondary outcomes are fatigue, health-related quality of life and musculoskeletal problems (self-reported questionnaires), number of sick leave days (diaries), diabetes medications (clinical record review) and cardiometabolic biomarkers including waist circumference, mean blood pressure, HbA1c, HDL-cholesterol and triglycerides.

DISCUSSION

Successful interventions to increase physical activity among those with T2DM have been costly and long-term effectiveness remains uncertain. The use of mHealth technologies such as activity trackers and SMS text reminders may increase awareness of prolonged sedentary behaviour and encourage increase in regular physical activity. mHealth may, therefore, provide a valuable and novel tool to improve health outcomes and clinical management in those with T2DM. This 12-month RCT will evaluate longer-term effects of a mHealth intervention suitable for real-world primary health care settings.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04219800 . Registered on 7 January 2020.

Young children's voices in an unlocked Sweden during the COVID-19 pandemic

Aims:

During the COVID-19 pandemic, Sweden was one of the few countries that rejected lockdowns in favour of recommendations for restrictions, including careful hand hygiene and social distancing. Preschools and primary schools remained open. Several studies have shown negative impacts of the pandemic on children, particularly high levels of anxiety. The study aim was to explore how Swedish school-aged children aged 6–14 years, experienced the COVID-19 pandemic and their perceived anxiety.

Methods:

In total, 774 children aged 6–14 years and their guardians answered an online questionnaire containing 24 questions, along with two instruments measuring anxiety: the Children’s Anxiety Questionnaire and the Numerical Rating Scale. A convergent parallel mixed-methods design was used for analysing the quantitative and qualitative data. Each data source was first analysed separately, followed by a merged interpretative analysis.

Results:

The results showed generally low levels of anxiety, with no significant sex differences. Children who refrained from normal social activities or group activities (n=377) had significantly higher levels of anxiety. Most of the children were able to appreciate the bright side of life, despite the social distancing and refraining from activities, which prevented them from meeting and hugging their loved ones.

Conclusions:

These Swedish children generally experienced low levels of anxiety, except those who refrained from social activities. Life was nonetheless mostly experienced as normal, largely because schools remained open. Keeping life as normal as possible could be one important factor in preventing higher anxiety and depression levels in children during a pandemic.

Competing oxidation mechanisms in Cu nanoparticles and their plasmonic signatures

Chemical reactions involving nanoparticles often follow complex processes. In this respect, real-time probing of single nanoparticles under reactive conditions is crucial for uncovering the mechanisms driving the reaction pathway. Here, we have captured in situ the oxidation of single Cu nanoparticles to unravel a sequential competitive activation of different mechanisms at temperatures 50-200 °C. Using environmental scanning transmission electron microscopy, we monitor the evolution of oxide formation with sub-nanometre spatial resolution, and show how the prevalence of oxide island nucleation, Cabrera-Mott, Valensi-Carter and Kirkendall mechanisms under different conditions determines the morphology of the particles. Moreover, using in situ electron energy-loss spectroscopy, we probe the localised surface plasmons of individual particles during oxidation, and with the aid of finite-difference time-domain electrodynamic simulations investigate the signature of each mechanism in their plasmonic response. Our results shed light on the rich and intricate processes involved in the oxidation of nanoparticles, and provide in-depth insight into how these processes govern their morphology and optical response, beneficial for applications in catalysis, sensing, nanomedicine and plasmonics.

To be or not to be vaccinated against COVID-19 - The adolescents' perspective - A mixed-methods study in Sweden

Vaccination of the population seems to be an important strategy in halting the COVID-19 pandemic in both local and global society. The aim of this study was to explore Swedish adolescents' willingness to be vaccinated against COVID-19 and its association with sociodemographic and other possible factors. A survey was distributed in Sweden between 7 July and 8 November 2020. The main qualitative question concerned adolescents' thoughts on vaccination against COVID-19 and evaluated whether the adolescents would like to be vaccinated when a COVID-19 vaccine is made available. In total, 702 adolescents aged between 15 and 19 responded to the questionnaire. A convergent parallel mixed-methods design was used. The results showed that nearly one in three adolescents had not decided if they wanted to get a COVID-19 vaccine, i.e. 30.5%: n = 214. Of the participants 54.3% (n = 381) were willing to be vaccinated. Girls had higher levels of anxiety about the vaccine compared to boys. In addition, high levels of anxiety impacted on the participants' willingness to be vaccinated. One reason for being undecided about the vaccine was that participants felt they did not know enough about it. Practising social distancing increased willingness to be vaccinated, as reflected in the qualitative results which showed participants wanted to be vaccinated to protect others. The results impart important knowledge to healthcare professionals and contribute to their communication with adolescents about vaccine hesitancy.

Grain-growth mediated hydrogen sorption kinetics and compensation effect in single Pd nanoparticles

Grains constitute the building blocks of polycrystalline materials and their boundaries determine bulk physical properties like electrical conductivity, diffusivity and ductility. However, the structure and evolution of grains in nanostructured materials and the role of grain boundaries in reaction or phase transformation kinetics are poorly understood, despite likely importance in catalysis, batteries and hydrogen energy technology applications. Here we report an investigation of the kinetics of (de)hydriding phase transformations in individual Pd nanoparticles. We find dramatic evolution of single particle grain morphology upon cyclic exposure to hydrogen, which we identify as the reason for the observed rapidly slowing sorption kinetics, and as the origin of the observed kinetic compensation effect. These results shed light on the impact of grain growth on kinetic processes occurring inside nanoparticles, and provide mechanistic insight in the observed kinetic compensation effect.

Grains are the building blocks of crystalline solids. Here the authors show how hydrogen-sorption induced grain-growth in Pd nanoparticles slows down the hydrogen sorption kinetics and constitutes the physical origin of corresponding kinetic compensation.

Light-Off in Plasmon-Mediated Photocatalysis

In plasmon-mediated photocatalysis it is of critical importance to differentiate light-induced catalytic reaction rate enhancement channels, which include near-field effects, direct hot carrier injection, and photothermal catalyst heating. In particular, the discrimination of photothermal and hot electron channels is experimentally challenging, and their role is under keen debate. Here we demonstrate using the example of CO oxidation over nanofabricated neat Pd and Au50Pd50 alloy catalysts, how photothermal rate enhancement differs by up to 3 orders of magnitude for the same photon flux, and how this effect is controlled solely by the position of catalyst operation along the light-off curve measured in the dark. This highlights that small fluctuations in reactor temperature or temperature gradients across a sample may dramatically impact global and local photothermal rate enhancement, respectively, and thus control both the balance between different rate enhancement mechanisms and the way strategies to efficiently distinguish between them should be devised.

Shedding Light on CO Oxidation Surface Chemistry on Single Pt Catalyst Nanoparticles Inside a Nanofluidic Model Pore

Investigating a catalyst under relevant application conditions is experimentally challenging and parameters like reaction conditions in terms of temperature, pressure, and reactant mixing ratios, as well as catalyst design, may significantly impact the obtained experimental results. For Pt catalysts widely used for the oxidation of carbon monoxide, there is keen debate on the oxidation state of the surface at high temperatures and at/above atmospheric pressure, as well as on the most active surface state under these conditions. Here, we employ a nanoreactor in combination with single-particle plasmonic nanospectroscopy to investigate individual Pt catalyst nanoparticles localized inside a nanofluidic model pore during carbon monoxide oxidation at 2 bar in the 450-550 K temperature range. As a main finding, we demonstrate that our single-particle measurements effectively resolve a kinetic phase transition during the reaction and that each individual particle has a unique response. Based on spatially resolved measurements, we furthermore observe how reactant concentration gradients formed due to conversion inside the model pore give rise to position-dependent kinetic phase transitions of the individual particles. Finally, employing extensive electrodynamics simulations, we unravel the surface chemistry of the individual Pt nanoparticles as a function of reactant composition and find strongly temperature-dependent Pt-oxide formation and oxygen spillover to the SiO2 support as the main processes. These results therefore support the existence of a Pt surface oxide in the regime of high catalyst activity and demonstrate the possibility to use plasmonic nanospectroscopy in combination with nanofluidics as a tool for in situ studies of individual catalyst particles.

Copper catalysis at operando conditions-bridging the gap between single nanoparticle probing and catalyst-bed-averaging

In catalysis, nanoparticles enable chemical transformations and their structural and chemical fingerprints control activity. To develop understanding of such fingerprints, methods studying catalysts at realistic conditions have proven instrumental. Normally, these methods either probe the catalyst bed with low spatial resolution, thereby averaging out single particle characteristics, or probe an extremely small fraction only, thereby effectively ignoring most of the catalyst. Here, we bridge the gap between these two extremes by introducing highly multiplexed single particle plasmonic nanoimaging of model catalyst beds comprising 1000 nanoparticles, which are integrated in a nanoreactor platform that enables online mass spectroscopy activity measurements. Using the example of CO oxidation over Cu, we reveal how highly local spatial variations in catalyst state dynamics are responsible for contradicting information about catalyst active phase found in the literature, and identify that both surface and bulk oxidation state of a Cu nanoparticle catalyst dynamically mediate its activity.

Operando detection of single nanoparticle activity dynamics inside a model pore catalyst material

Nanoconfinement in porous catalysts may induce reactant concentration gradients inside the pores due to local conversion. This leads to inefficient active material use since parts of the catalyst may be trapped in an inactive state. Experimentally, these effects remain unstudied due to material complexity and required high spatial resolution. Here, we have nanofabricated quasi-two-dimensional mimics of porous catalysts, which combine the traits of nanofluidics with single particle plasmonics and online mass spectrometry readout. Enabled by single particle resolution at operando conditions during CO oxidation over a Cu model catalyst, we directly visualize reactant concentration gradient formation due to conversion on single Cu nanoparticles inside the "model pore" and how it dynamically controls oxidation state-and, thus, activity-of particles downstream. Our results provide a general framework for single particle catalysis in the gas phase and highlight the importance of single particle approaches for the understanding of complex catalyst materials.

A nanofabricated plasmonic core-shell-nanoparticle library

Three-layer core-shell-nanoparticle nanoarchitectures exhibit properties not achievable by single-element nanostructures alone and have great potential to enable rationally designed functionality. However, nanofabrication strategies for crafting core-shell-nanoparticle structure arrays on surfaces are widely lacking, despite the potential of basically unlimited material combinations. Here we present a nanofabrication approach that overcomes this limitation. Using it, we produce a library of nanoarchitectures composed of a metal core and an oxide/nitride shell that is decorated with few-nanometer-sized particles with widely different material combinations. This is enabled by resolving a long-standing challenge in this field, namely the ability to grow a shell layer around a nanofabricated core without prior removal of the lithographically patterned mask, and the possibility to subsequently grow smaller metal nanoparticles locally on the shell only in close proximity of the core. Focusing on the application of such nanoarchitectures in plasmonics, we show experimentally and by Finite-Difference Time-Domain (FDTD) simulations that these structures exhibit significant optical absorption enhancement in small metal nanoparticles grown on the few nanometer thin dielectric shell layer around a plasmonic core, and derive design rules to maximize the effect by the tailored combination of the core and shell materials. We predict that these structures will find application in plasmon-mediated catalysis and nanoplasmonic sensing and spectroscopy.

Resolving single Cu nanoparticle oxidation and Kirkendall void formation with in situ plasmonic nanospectroscopy and electrodynamic simulations

Copper nanostructures are ubiquitous in microelectronics and heterogeneous catalysis and their oxidation is a topic of high current interest and broad relevance. It relates to important questions, such as catalyst active phase, activity and selectivity, as well as fatal failure of microelectronic devices. Despite the obvious importance of understanding the mechanism of Cu nanostructure oxidation, numerous open questions remain, including under what conditions homogeneous oxide layer growth occurs and when the nanoscale Kirkendall void forms. Experimentally, this is not trivial to investigate because when a large number of nanoparticles are simultaneously probed, ensemble averaging makes rigorous conclusions difficult. On the other hand, when (in situ) electron-microscopy approaches with single nanoparticle resolution are applied, concerns about beam effects that may both reduce the oxide or prevent oxidation via the deposition and cross-linking of carbonaceous species cannot be neglected. In response we present how single particle plasmonic nanospectroscopy can be used for the in situ real time characterization of multiple individual Cu nanoparticles during oxidation. Our analysis of their optical response combined with post mortem electron microscopy imaging and detailed Finite-Difference Time-Domain electrodynamics simulations enables in situ identification of the oxidation mechanism both in the initial oxide shell growth phase and during Kirkendall void formation, as well as the transition between them. In a wider perspective, this work presents the foundation for the application of single particle plasmonic nanospectroscopy in investigations of the impact of parameters like particle size, shape and grain structure with respect to defects and grain boundaries on the oxidation of metal nanoparticles.

A nanofluidic device for parallel single nanoparticle catalysis in solution

Studying single catalyst nanoparticles, during reaction, eliminates averaging effects that are an inherent limitation of ensemble experiments. It enables establishing structure-function correlations beyond averaged properties by including particle-specific descriptors such as defects, chemical heterogeneity and microstructure. Driven by these prospects, several single particle catalysis concepts have been implemented. However, they all have limitations such as low throughput, or that they require very low reactant concentrations and/or reaction rates. In response, we present a nanofluidic device for highly parallelized single nanoparticle catalysis in solution, based on fluorescence microscopy. Our device enables parallel scrutiny of tens of single nanoparticles, each isolated inside its own nanofluidic channel, and at tunable reaction conditions, ranging from the fully mass transport limited regime to the surface reaction limited regime. In a wider perspective, our concept provides a versatile platform for highly parallelized single particle catalysis in solution and constitutes a promising application area for nanofluidics.

In Situ Plasmonic Nanospectroscopy of the CO Oxidation Reaction over Single Pt Nanoparticles

The ongoing quest to develop single-particle methods for the in situ study of heterogeneous catalysts is driven by the fact that heterogeneity in terms of size, shape, grain structure, and composition is a general feature among nanoparticles in an ensemble. This heterogeneity hampers the generation of a deeper understanding for how these parameters affect catalytic properties. Here we present a solution that in a single benchtop experimental setup combines single-particle plasmonic nanospectroscopy with mass spectrometry for gas phase catalysis under reaction conditions at high temperature. We measure changes in the surface state of polycrystalline platinum model catalyst particles in the 70 nm size range and the corresponding bistable kinetics during the carbon monoxide oxidation reaction via the peak shift of the dark-field scattering spectrum of a closely adjacent plasmonic nanoantenna sensor and compare these changes with the total reaction rate measured by the mass spectrometer from an ensemble of nominally identical particles. We find that the reaction kinetics of simultaneously measured individual Pt model catalysts are dictated by the grain structure and that the superposition of the individual nanoparticle response can account for the significant broadening observed in the corresponding nanoparticle ensemble data. In a wider perspective our work enables in situ plasmonic nanospectroscopy in controlled gas environments at high temperature to investigate the role of the surface state on transition metal catalysts during reaction and of processes such as alloying or surface segregation in situ at the single-nanoparticle level for model catalysts in the few tens to hundreds of nanometer size range.

Interleukin 4 induces rapid mucin transport, increases mucus thickness and quality and decreases colitis and Citrobacter rodentium in contact with epithelial cells

Citrobacter rodentium infection is a murine model for pathogenic intestinal Escherichia coli infection. C. rodentium infection causes an initial decrease in mucus layer thickness, followed by an increase during clearance. We aimed to identify the cause of these changes and to utilize this naturally occurring mucus stimulus to decrease pathogen impact and inflammation. We identified that mucin production and speed of transport from Golgi to secretory vesicles at the apical surface increased concomitantly with increased mucus thickness. Of the cytokines differentially expressed during increased mucus thickness, IFN-γ and TNF-α decreased the mucin production and transport speed, whereas IL-4, IL-13, C. rodentium and E. coli enhanced these aspects. IFN-γ and TNF-α treatment in combination with C. rodentium and pathogenic E. coli infection negatively affected mucus parameters in vitro, which was relieved by IL-4 treatment. The effect of IL-4 was more pronounced than that of IL-13, and in wild type mice, only IL-4 was present. Increased expression of Il-4, Il-4-receptor α, Stat6 and Spdef during clearance indicate that this pathway contributes to the increase in mucin production. In vivo IL-4 administration initiated 10 days after infection increased mucus thickness and quality and decreased colitis and pathogen contact with the epithelium. Thus, during clearance of infection, the concomitant increase in IL-4 protects and maintains goblet cell function against the increasing levels of TNF-α and IFN-γ. Furthermore, IL-4 affects intestinal mucus production, pathogen contact with the epithelium and colitis. IL-4 treatment may thus have therapeutic benefits for mucosal healing.

Heterodimers for in Situ Plasmonic Spectroscopy: Cu Nanoparticle Oxidation Kinetics, Kirkendall Effect, and Compensation in the Arrhenius Parameters

The ability to study oxidation, reduction, and other chemical transformations of nanoparticles in real time and under realistic conditions is a nontrivial task due to their small dimensions and the often challenging environment in terms of temperature and pressure. For scrutinizing oxidation of metal nanoparticles, visible light optical spectroscopy based on the plasmonic properties of the metal has been established as a suitable method. However, directly relying on the plasmonic resonance of metal nanoparticles as a built-in probe to track oxidation has a number of drawbacks, including the loss of optical contrast in the late oxidation stages. To address these intrinsic limitations, we present a plasmonic heterodimer-based nanospectroscopy approach, which enables continuous self-referencing by using polarized light to eliminate parasitic signals and provides large optical contrast all the way to complete oxidation. Using Au-Cu heterodimers and combining experiments with finite-difference time-domain simulations, we quantitatively analyze the oxidation kinetics of ca. 30 nm sized Cu nanoparticles up to complete oxidation. Taking the Kirkendall effect into account, we extract the corresponding apparent Arrhenius parameters at various extents of oxidation and find that they exhibit a significant compensation effect, implying that changes in the oxidation mechanism occur as oxidation progresses and the structure of the formed oxide evolves. In a wider perspective, our work promotes the use of model-system-type in situ optical plasmonic spectroscopy experiments in combination with electrodynamics simulations to quantitatively analyze and mechanistically interpret oxidation of metal nanoparticles and the corresponding kinetics in demanding chemical environments, such as in heterogeneous catalysis.

Neonatal gut colonization by Staphylococcus aureus strains with certain adhesins and superantigens is negatively associated with subsequent development of atopic eczema

BACKGROUND

Insufficient early immune stimulation may predispose to atopic disease. Staphylococcus aureus, a skin and gut colonizer, produces the B-cell mitogen protein A and T-cell-activating superantigens. Early gut colonization by S. aureus strains that possess the superantigens encoded by the enterotoxin gene (egc) cluster and elastin-binding protein is negatively associated with development of atopic eczema.

OBJECTIVES

To investigate (i) whether these findings could be replicated in a second birth cohort, FARMFLORA, and (ii) whether nasal colonization by S. aureus also relates to subsequent atopic eczema development.

METHODS

Faecal samples and nasal swabs from infants in the FARMFLORA birth cohort (n = 65) were cultured for S. aureus. Individual strains were distinguished by random amplified polymorphic DNA and assessed for adhesin and superantigen gene carriage by polymerase chain reaction. Atopic eczema at 18 months of age was related to nasal and gut S. aureus colonization patterns during the first 2 months of life (well before onset of eczema).

RESULTS

Staphylococcus aureus colonization per se was unrelated to subsequent eczema development. However, gut S. aureus strains from the infants who subsequently developed atopic eczema less frequently carried the ebp gene, encoding elastin-binding protein, and superantigen genes encoded by egc, compared with strains from children who remained healthy. Nasal colonization by S. aureus was less clearly related to subsequent eczema development.

CONCLUSIONS

The results precisely replicate our previous observations and may suggest that mucosal colonization by certain S. aureus strains provides immune stimulation that strengthens the epithelial barrier and counteracts the development of atopic eczema.

A fiber-optic nanoplasmonic hydrogen sensor via pattern-transfer of nanofabricated PdAu alloy nanostructures

We demonstrate the transfer of arrays of nanofabricated noble metal and alloy nanostructures obtained by high-temperature annealing on a flat parent support onto optical fibers, to create a hysteresis-free fiber optic nanoplasmonic hydrogen sensor. This work enables the integration of complex nanofabricated structures and their arrangements in tailored arrays with fiber optics to realize optical sensors, which will find application in a wide range of disciplines.

Efficacy of selective serotonin reuptake inhibitors in the absence of side effects: a mega-analysis of citalopram and paroxetine in adult depression

It has been suggested that the superiority of antidepressants over placebo in controlled trials is merely a consequence of side effects enhancing the expectation of improvement by making the patient realize that he/she is not on placebo. We explored this hypothesis in a patient-level post hoc-analysis including all industry-sponsored, Food and Drug Administration-registered placebo-controlled trials of citalopram or paroxetine in adult major depression that used the Hamilton Depression Rating Scale (HDRS) and included a week 6 symptom assessment (n=15). The primary analyses, which compared completers on active treatment without early adverse events to completers on placebo (with or without adverse events) with respect to reduction in the HDRS depressed mood item showed larger symptom reduction in patients given active treatment, the effect sizes being 0.48 for citalopram and 0.33 for paroxetine. In actively treated subjects reporting early adverse events, who also outperformed those given placebo, the severity of the adverse events did not predict response. Several sensitivity analyses, for example, including (i) those using change of the sum of all HDRS-17 items as effect parameter, (ii) those excluding all subjects with adverse events (that is, also those on placebo) and (iii) those based on the intention-to-treat population, were all in line with the primary analyses. The finding that both paroxetine and citalopram are clearly superior to placebo also when not producing adverse events, as well as the lack of association between adverse event severity and response, argue against the theory that antidepressants outperform placebo solely or largely because of their side effects.

Clinical Profile of a New Monoclonal Antibody-Based Immunoassay for Tissue Polypeptide Antigen

Our preliminary evaluation of a new monoclonal antibody-based assay for tissue polypeptide antigen (TPA) has shown it to be clinically equivalent to the polyclonal antibody-based assay for TPA. The new assay (TPA-M) employs three monoclonal antibodies to epitopes on cytokeratins 8, 18 and 19. This multicenter, multinational study included 266 patients with newly diagnosed carcinomas of the lung, breast, large bowel and urinary bladder. TPA values from the two assays were compared with three other cytokeratin markers (TPS, CYFRA 21–1 and TPACyk) and with the established reference markers for these malignancies (CEA and NSE for lung, CA 15–3 for breast, CEA and CA 19–9 for colorectal tumors). Analysis of receiver operating characteristic (ROC) curves in lung, colorectal and bladder cancer showed similar sensitivities for the two assays, ranging from 50% to 80% with a specificity of 95%. In breast cancer all the markers studied showed poor sensitivity. However, TPA determination by either method could discriminate advanced stage (stages III and IV) from early stage disease (stages 0 to II). TPA showed similar discriminating ability in bladder cancer. On the basis of the results obtained in our patient series, it seems that of the cytokeratin markers studied, TPA and TPA-M are the most sensitive and offer a wide range of clinical applications.

An exploratory analysis of alkaline phosphatase, lactate dehydrogenase, and prostate-specific antigen dynamics in the phase 3 ALSYMPCA trial with radium-223

Background

Baseline clinical variables are prognostic for overall survival (OS) in patients with castration-resistant prostate cancer (CRPC). Their prognostic and predictive value with agents targeting bone metastases, such as radium-223, is not established.

Patients and methods

The radium-223 ALSYMPCA trial enrolled patients with CRPC and symptomatic bone metastases. Prognostic potential of baseline variables was assessed using Cox models. Percentage changes in biomarker levels from baseline were evaluated during the trial period; changes from baseline to week 12 were evaluated for association with OS and surrogacy.

Results

Eastern Cooperative Oncology Group performance status, total alkaline phosphatase (tALP), lactate dehydrogenase (LDH), and prostate-specific antigen (PSA) at baseline were associated with OS (P ≤ 0.0003) in the intent-to-treat population (radium-223, N = 614; placebo, N = 307). tALP declined from baseline within 4 weeks after beginning radium-223, by week 12 declining in 87% of radium-223 and 23% of placebo patients (P < 0.001). LDH declined in 51% and 34% (P = 0.003), whereas PSA declined in 27% and 14% (P = 0.160). Mean tALP change from baseline was 32.2% decrease with radium-223 and 37.2% increase with placebo. Radium-223 patients with tALP decline from baseline to week 12 (confirmed ≥3 weeks from week 12) had 55% lower risk of death (hazard ratio = 0.45; 95% CI 0.34-0.61) versus those with no confirmed tALP decline. Proportional treatment effect (PTE) values for tALP, LDH, and PSA changes from baseline at week 12 as OS surrogate markers were 0.34 (95% CI: 0-0.746), 0.07 (95% CI: 0-0.211), and 0 (95% CI: 0-0.082), respectively.

Conclusions

Significant tALP declines (versus placebo) occurred as early as 4 weeks after beginning radium-223 therapy. tALP or LDH declines at 12 weeks correlated with longer OS, but did not meet statistical surrogacy requirements. Dynamic changes in tALP and LDH during radium-223 treatments may be useful to monitor, but do not serve as surrogates for survival.

Does asthma affect school performance in adolescents? Results from the Swedish population-based birth cohort BAMSE

BACKGROUND

Asthma is common among schoolchildren and may influence quality of life and school attendance. However, it is unclear if asthma affects school performance. The aim of this study was to examine whether different phenotypes of asthma affect school performance during adolescence.

METHODS

The study population consisted of 1715 adolescents from a population-based birth cohort, followed up to age 16 with questionnaires and clinical examinations. Asthma was defined as at least 4 wheeze episodes or at least 1 wheeze episode in combination with inhaled steroids in the last 12 months. School grades were obtained from Statistics Sweden, and logistic regression analysis was performed to investigate the association between the final overall grade from secondary school and asthma phenotypes.

RESULTS

Among the adolescents, 20.8% have had ever asthma; 24.2% early transient, 47.2% school-age onset, and 24.2% persistent asthma. At 16 years, 7.8% had asthma; 71.7% multimorbidity and 73.9% allergic asthma. A statistically significant association for performing less well was seen for ever asthma (OR_adj  = 1.43, 95% CI = 1.09-1.88). In analyses of asthma onset, an association was seen for school-age onset (OR_adj  = 1.49, CI = 1.02-2.16) and a tendency for persistent asthma (OR_adj  = 1.61, CI = 0.98-2.66), although with overlapping confidence intervals. Further, adolescents with uncontrolled asthma tended to perform less well (OR_adj  = 2.60, CI = 0.87-7.80) compared to adolescents with partly controlled (OR_adj  = 1.12, CI = 0.68-1.83) and fully controlled (OR_adj  = 1.29, CI = 0.55-3.01) asthma.

CONCLUSIONS

Our results indicate that asthma impairs school performance in adolescence. Moreover, some evidence suggests the adolescents with asthma during school age and with poorer asthma control to be more likely to perform less well.

Polyunsaturated fatty acids in plasma at 8 years and subsequent allergic disease

BACKGROUND

Polyunsaturated fatty acids (PUFAs) are hypothesized to modulate the risk of allergic disease. However, evidence from previous studies is inconclusive, and limited longitudinal data exist using circulating biomarkers of PUFA intake and metabolism.

OBJECTIVE

We aimed to investigate associations between n-3 and n-6 PUFAs at age 8 years and asthma, rhinitis, and aeroallergen sensitization at age 16 years.

METHODS

Proportions of n-3 PUFAs (very long-chain n-3 [VLC n-3; sum of eicosapentaenoic acid, docosapentaenoic acid, and docosahexaenoic acid] and α-linolenic acid) and n-6 PUFAs (linoleic acid and arachidonic acid [AA]) in blood samples at age 8 years were measured for 940 children from the prospective Swedish birth cohort BAMSE (Children, Allergy, Milieu, Stockholm, Epidemiology). Allergic disease phenotypes were defined by using questionnaires and IgE measures at the ages of 8 and 16 years. Logistic regression was used to examine potential associations.

RESULTS

A higher proportion of total VLC n-3 PUFAs in plasma at age 8 years was associated with a reduced risk of prevalent asthma, rhinitis, and aeroallergen sensitization at age 16 years and with incidence of asthma between 8 and 16 years (adjusted odds ratio, 0.67; 95% CI, 0.47-0.94). AA was associated with a reduced risk of asthma, aeroallergen sensitization, and allergic rhinitis. The findings were most evident for allergic phenotypes of asthma and rhinitis. Additionally, AA was associated with an increased probability of asthma and rhinitis remission between 8 and 16 years of age.

CONCLUSION

Higher proportions of certain VLC n-3 and very long-chain n-6 PUFAs in plasma phospholipids at age 8 years were associated with a reduced risk of allergic disease at age 16 years.

Incidence of early anxiety aggravation in trials of selective serotonin reuptake inhibitors in depression

OBJECTIVE

Selective serotonin reuptake inhibitors (SSRIs) may aggravate anxiety and agitation during the first days of treatment but the frequency of such reactions remains unknown.

METHOD

We analysed patient-level data from placebo-controlled trials of sertraline, paroxetine or citalopram in depressed adults. Somatic anxiety, psychic anxiety and psychomotor agitation as assessed using the Hamilton Depression Rating Scale (HDRS) were analysed in all trials (n = 8262); anxiety-related adverse events were analysed in trials investigating paroxetine and citalopram (n = 5712).

RESULTS

After one but not two weeks, patients on an SSRI were more likely than those on placebo to report enhanced somatic anxiety (adjusted risk 9.3% vs. 6.7%); likewise, mean rating of somatic anxiety was higher in the SSRI group. In contrast, patients receiving an SSRI were less likely to report aggravation of psychic anxiety (adjusted risk: 7.0% vs. 8.5%) with mean rating of psychic anxiety and agitation being lower in the SSRI group. The adverse event 'nervousness' was more common in patients given an SSRI (5.5% vs. 2.5%). Neither aggravation of HDRS-rated anxiety nor anxiety-related adverse events predicted poor antidepressant response.

CONCLUSION

Whereas an anxiety-reducing effect of SSRIs is notable already during the first week of treatment, these drugs may also elicit an early increase in anxiety in susceptible subjects that however does not predict a poor subsequent response to treatment.

Transcriptome sequencing in pediatric acute lymphoblastic leukemia identifies fusion genes associated with distinct DNA methylation profiles

BACKGROUND

Structural chromosomal rearrangements that lead to expressed fusion genes are a hallmark of acute lymphoblastic leukemia (ALL). In this study, we performed transcriptome sequencing of 134 primary ALL patient samples to comprehensively detect fusion transcripts.

METHODS

We combined fusion gene detection with genome-wide DNA methylation analysis, gene expression profiling, and targeted sequencing to determine molecular signatures of emerging ALL subtypes.

RESULTS

We identified 64 unique fusion events distributed among 80 individual patients, of which over 50% have not previously been reported in ALL. Although the majority of the fusion genes were found only in a single patient, we identified several recurrent fusion gene families defined by promiscuous fusion gene partners, such as ETV6, RUNX1, PAX5, and ZNF384, or recurrent fusion genes, such as DUX4-IGH. Our data show that patients harboring these fusion genes displayed characteristic genome-wide DNA methylation and gene expression signatures in addition to distinct patterns in single nucleotide variants and recurrent copy number alterations.

CONCLUSION

Our study delineates the fusion gene landscape in pediatric ALL, including both known and novel fusion genes, and highlights fusion gene families with shared molecular etiologies, which may provide additional information for prognosis and therapeutic options in the future.

Rationale and design of the multiethnic Pharmacogenomics in Childhood Asthma consortium

AIM

International collaboration is needed to enable large-scale pharmacogenomics studies in childhood asthma. Here, we describe the design of the Pharmacogenomics in Childhood Asthma (PiCA) consortium.

MATERIALS & METHODS

Investigators of each study participating in PiCA provided data on the study characteristics by answering an online questionnaire.

RESULTS

A total of 21 studies, including 14,227 children/young persons (58% male), from 12 different countries are currently enrolled in the PiCA consortium. Fifty six percent of the patients are Caucasians. In total, 7619 were inhaled corticosteroid users. Among patients from 13 studies with available data on asthma exacerbations, a third reported exacerbations despite inhaled corticosteroid use. In the future pharmacogenomics studies within the consortium, the pharmacogenomics analyses will be performed separately in each center and the results will be meta-analyzed.

CONCLUSION

PiCA is a valuable platform to perform pharmacogenetics studies within a multiethnic pediatric asthma population.

Snapshot of cobalt, chromium and nickel exposure in dental technicians

BACKGROUND

It is not fully understood where and how people are exposed to sensitizing metals. Much can be learnt from studying occupational settings where metals are handled.

OBJECTIVES

To quantify cobalt (Co), chromium (Cr) and nickel (Ni) exposure on the skin and in the air, and urine levels, in dental technicians working with tools and alloys that may result in skin and respiratory exposure.

METHODS

The metal skin dose was quantified with acid wipe sampling in dental technicians (n = 13). Air exposure was monitored by personal air sampling. Spot urine samples were collected for 24 h. Metals were analysed with inductively coupled plasma mass spectrometry.

RESULTS

Before work, Co was detected on the skin of 10 participants (0.00025-0.0039 µg/cm² ), and Cr (0.00051-0.011 µg/cm² ) and Ni (0.0062-0.15 µg/cm² ) on the skin of all participants. After a 2-h period without hand washing, CoCr-exposed participants had more Co on the skin (p = 0.004) than non-CoCr-exposed participants. Co was found in 10 air samples (0.22-155 µg/m³ ), Cr in nine (0.43-71 µg/m³ ), and Ni in four (0.48-3.7 µg/m³ ). Metal urine concentrations were considered to be normal.

CONCLUSIONS

Dental technicians were exposed to Co, Cr and Ni on the skin and through the air, which was not reflected in the urine concentrations in this study. Cobalt skin doses may potentially elicit allergic contact dermatitis and cause sensitization.

Expectation prior to human papilloma virus vaccination: 11 to 12-Year-old girls' written narratives

Expectations prior to needle-related procedures can influence individuals' decision making and compliance with immunization programmes. To protect from human papilloma virus (HPV) and cervical cancer, the immunization needs to be given before sexual debut raising interest for this study's aim to investigate how 11 to 12-year-old girls narrate about their expectations prior to HPV vaccination. A total of 27 girls aged 11 to 12 years participated in this qualitative narrative study by writing short narratives describing their expectations. The requirement for inclusion was to have accepted HPV vaccination. Data were subjected to qualitative content analysis. Findings showed the following expectations: going to hurt, going to be scared and going to turn out fine. The expectations were based on the girls' previous experiences, knowledge and self-image. The latent content revealed that the girls tried to transform uneasiness to confidence. The conclusion drawn from this study is that most girls of this age seem confident about their ability to cope with possible unpleasantness related to vaccinations. However, nurses need to find strategies to help those children who feel uneasy about needle-related procedures.