Addressing adverse synergies between chemical and biological pollutants at schools—The ‘SynAir-G’ hypothesis

While the number and types of indoor air pollutants is rising, much is suspected but little is known about the impact of their potentially synergistic interactions, upon human health. Gases, particulate matter, organic compounds but also allergens and viruses, fall within the ‘pollutant’ definition. Distinct populations, such as children and allergy and asthma sufferers are highly susceptible, while a low socioeconomic background is a further susceptibility factor; however, no specific guidance is available. We spend most of our time indoors; for children, the school environment is of paramount importance and potentially amenable to intervention. The interactions between some pollutant classes have been studied. However, a lot is missing with respect to understanding interactions between specific pollutants of different classes in terms of concentrations, timing and sequence, to improve targeting and upgrade standards. SynAir‐G is a European Commission‐funded project aiming to reveal and quantify synergistic interactions between different pollutants affecting health, from mechanisms to real life, focusing on the school setting. It will develop a comprehensive and responsive multipollutant monitoring system, advance environmentally friendly interventions, and disseminate the generated knowledge to relevant stakeholders in accessible and actionable formats. The aim of this article it to put forward the SynAir‐G hypothesis, and describe its background and objectives

Studien über die Oberflächeneigenschaften von Nanopartikeln

The origin of nanoparticles unique properties often lies within their surface region or is based on the texture of their surface. The use of nanoparticles as catalysis eventuates from their high surface to volume ratio. Also without the interplay of the nanoparticle surface with the surrounding water molecules no contrast enhancement in magnetic resonance imaging (MRI) would exist. Iron oxide nanoparticles, synthesized by thermal decomposition from organometallic compounds, consists of non-defined ratios of magnetite (Fe3O4) and maghemite (gamma-Fe2O3) based on synthesis conditions and post-synthetis treatment. Therefore, it is not possible to distinguish the two modifications via standard methods such as X-ray diffraction. Since magnetite shows a much higher saturation magnetization than maghemite, the knowledge of the exact composition of the nanoparticle surface is crucial for later application in MRI. Within this thesis, the local structure and composition as well as the electronic properties of the outer layer of varrying sized iron oxide nanoparticles were investigated via X-ray absorption spectroscopy (XAS) and X-ray magnetic circular dichroism (XMCD). Additionaly, the influence of specific, post-synthetic oxidation was studied. Ongoing oxidation time resulted in an increase in the maghemite proportion and a reduction in the spin canting which were found to result in a higher magnetizability of the samples. Since iron oxide nanoparticles synthesized by thermal decomposition possess a hydrophobic ligand shell, which hinders any in-vivo-application, a post-synthetic ligand exchange with hydrophilic ligands is necessary. The influence of typical an chor groups of these ligands, such as catechols or citric acid, on the nanoparticle surface after an exchange, was studied by XMCD and XAS. Here it was revealed, that the magnetic properties of the nanoparticle surface, after the transfer into water, was the most preserved if the aromatic system of the anchor group was nitrated. The nitration did not influence the oxidation state of the iron in contrast to non nitrated derivatives and also the storage in isotonic saline solution at 37 °C for 24 h leads to no significant changes in the composition of the nanoparticle surface. The roughness of nanoparticles surface was also seen to influence the particle interaction with other surfaces. Until now only limited studies dealing with the determination of the roughness of nanoparticles exist. Three different silica nanoparticles systems with diameters of 100 nm, 250nm and 500 nm, each with three different roughnesses in the sub-nanometer regime, were synthesized for the first time. The perimeter and the expected surface, as well as the surface roughness were determined with a novel method based on transmission electron microscopy images. Only atomic force microscopy was able to provide similar roughness, however the degree of sample preparation and post-acquisition analysis is much greater.Die einzigartigen Eigenschaften von Nanopartikeln haben ihren Ursprung oftmals in der Oberflächenregion oder resultieren aus der Oberflächenbeschaffenheit dieser. So ist das hohe Oberflächen-zu-Volumen-Verhältnis für ihre Anwendung in der Katalyse entscheidend. Ohne die Wechselwirkung der magnetischen Oberfläche der Nanopartikel mit umgebenden Wassermolekülen wären keine Kontrastverstärkungen in der Magnetresonanztomografie (MRT) sichtbar. Eisenoxidnanopartikel, die durch thermische Zersetzung von organometallischen Verbindungen gewonnen werden, bestehen in einem von der Synthese und Behandlung abhängigen, nicht definierten Verhältnis aus Magnetit (Fe3O4) und Maghämit (gamma-Fe2O3). Die beiden Modifikationen können mit Standardmethoden wie Röntgenkristallbeugung nicht voneinander unterschieden werden. Da Magnetit eine wesentlich höhere Sättigungsmagnetisierung aufweist, ist eine genaue Kenntnis der Oberflächenzusammensetzung für eine spätere Verwendung in der MRT entscheidend. Zunächst wurde in dieser Arbeit mittels Röntgenabsorptionsspektroskopie (engl. X-ray absorption spectroscopy, XAS) und zirkularem magnetischen Röntgendichroismus (engl. X-ray magnetic circular dichroism, XMCD) die lokale Struktur und Zusammensetzung sowie die elektronischen Eigenschaften der äußeren Schicht von unterschiedlich großen Eisenoxidnanopartikeln studiert. Anschließend wurde der Einfluss einer gezielten Oxidation auf die Oberfläche untersucht, wobei mit zunehmender Oxidationszeit ein Anstieg des Maghämitanteils und eine Abnahme von Spinverkantungen mit einer daraus resultierenden höheren Magnetisierbarkeit der Proben beobachtet wurde. Zudem besitzen solche Eisenoxidnanopartikel eine hydrophobe Ligandenhülle, die eine in-vivo-Verwendung verhindert, weswegen ein postsynthetischer Ligandenaustausch gegen hydrophile Liganden durchgeführt werden muss. Deswegen wurde der Einfluss von typischen Ankergruppen solcher Liganden wie zum Beispiel Zitronensäure oder Catecholen auf die Oberfläche der Nanopartikel nach diesem Austausch mittels XAS und XMCD untersucht. Dabei zeigte sich, dass am aromatischen System nitrierte Catecholverbindungen die magnetischen Eigenschaften der Nanopartikeloberfläche beim Phasentransfer ins Wasser am effektivsten schützten. Auf den Oxidationszustand des Eisens hatte die Nitrierung, verglichen mit nicht nitrierten Catecholen, jedoch keinen Einfluss und auch eine Lagerung in isotonischer Kochsalzlösung bei 37 °C für 24 h führte zu keinen signifikanten Änderungen der Zusammensetzung der Nanopartikeloberfläche. Die Rauheit von Nanopartikeln kann die Wechselwirkung dieser mit Oberflächen verändern. Dennoch gibt es bis heute kaum Studien zur Bestimmung von Rauheiten von Nanopartikeln. So wurden in dieser Arbeit erstmalig drei unterschiedlich große Silicananopartikelsysteme mit Durchmessern von 100 nm, 250nm und 500nm mit jeweils drei unterschiedlichen Rauheiten im Subnanometerbereich dargestellt. Anschließend wurde mit einer neuartigen Analysemethode für Transmissionselektronenmikroskopieaufnahmen der Umfang und die zu erwartende Oberfläche sowie die Rauheit dieser bestimmt. Lediglich mittels Rasterkraftmikroskopieaufnahmen konnten zumindest für die größeren Systeme ähnliche Werte für die Rauheit ermitteln werden, wobei der Aufwand sowohl in der Probenvorbereitung als auch in der anschließenden Analyse um ein Vielfaches höher ist

I Live Alone but Don\u27t Feel Alone: Social Isolation and Loneliness From the Patient Perspective

A growing homebound population may be at risk for social isolation and loneliness. Health-related social needs play a contributing role in these conditions. Research shows social isolation and loneliness are drivers of health outcomes. This pilot feasibility study seeks to explore patient-centered insight into perceptions of social isolation and loneliness in a homebound population. Eight participants were recruited from a home-based primary care practice within a family medicine residency program. One 30-minute semi-structured interview was completed in participants’ homes. The interview focused on loneliness and social isolation, using the 6-item De Jong Gerveld loneliness scale. Three qualitative analysts open-coded transcriptions independently. Themes were defined using thematic analysis, then triangulated around a consensus of themes. Patients denied loneliness, but most described social isolation, highlighting the potential need for more targeted documentation and intervention in this arena. The most reported barrier affecting social isolation in our study population was mobility issues. The patient perspective is useful to focus the target of approach. Based on this pilot, additional research with a larger sample size across multiple sites is warranted to further explore homebound patients’ experience of loneliness and social isolation in order to better guide assessment and interventions for these common problems

Rapid Evaluation of the Mycobactericidal Efficacy of Disinfectants in the Quantitative Carrier Test EN 14563 by Using Fluorescent Mycobacterium terrae▿ †

To prevent transmission of mycobacterial pathogens, medical devices must be disinfected by germicides with proven mycobactericidal activity. The quantitative carrier test EN 14563 provides an international standard for evaluation of the mycobactericidal activity of disinfectants under practical conditions. However, tests according to the EN 14563 standard are based on cultivation, and results are available only after 21 days. The aim of this study was to accelerate assessment of dosage and contact times of mycobactericidal preparations based on the EN 14563 standard. To this end, a gfp gene was constructed with a codon usage adapted for Mycobacterium tuberculosis. Expression of the gfpm2+ gene in Mycobacterium terrae improved the detection sensitivity by 10-fold over that with a previously used reporter strain. Peracetic acid and a cation-active formulation were tested as commercially available disinfectants for medical devices. M. terrae expressing gfpm2+ was used to determine dosage and contact times for the two test germicides. Fluorescence measurements correlated well with growth of the reporter strain, demonstrating that the fluorescence reliably indicated the number of viable cells. The fluorescence enabled us to determine the mycobactericidal efficacy of the test disinfectants according to the quantitative carrier test EN 14563 standard within at least 15 days. In conclusion, this study establishes gfpm2+-expressing M. terrae as a new reporter strain for reliable evaluation of mycobactericidal activities of disinfectants with a superior sensitivity and in a significantly shorter time than previously possible

Kinetics of aggregation and growth processes of PEG-stabilised mono- and multivalent gold nanoparticles in highly concentrated halide solutions

5-6 nm gold nanoparticles were prepared by hydrolytic decomposition of [NMe4]-[Au(CF3)(2)] and functionalized in situ with mono-and multivalent thiolated PEG ligands. Time-dependent changes of the nanoparticles were monitored in aqueous NaCl, NaBr, and NaI solutions by UV-Vis spectroscopy, TEM, and HRTEM. The purely sterically protected particles are stable in = 2 M), the monovalent stabilized particles show minor reaction limited colloidal aggregation. In NaBr but not in NaCl solutions a minor Ostwald ripening also occurs. The divalent stabilized particles remain colloidally stable in both halide solutions, even if the temperature is raised or the concentration is increased above 2 M. In <= 1 M aqueous NaI solutions the particles remain stable. Above, the monovalent stabilized particles undergo an oxidative reaction, resulting in a time-dependent shift and broadening of the absorbance spectrum. Finally, this process slows down while the width of the spectra slightly narrows. The kinetics of this process can be described by a two-step sigmoidal process, comprising a slow induction period where active species are formed, followed by a fast growth and aggregation process. The increasing concentration of fused structures from the aggregates during this process results in a narrowing of the size distributions. The divalent stabilized particles show only some minor broadening and a slight shift of the absorbance spectra in <= 3 M NaI solutions. These observations confirm the excellent stability of the multivalent stabilized particles from this chloride-free particle synthesis

Local Magnetic and Electronic Structure of the Surface Region of Postsynthesis Oxidized Iron Oxide Nanoparticles for Magnetic Resonance Imaging

Iron oxide nanoparticles (FeO_<i>x</i>-NP) are applied in medicine as contrast agents in magnetic resonance imaging (MRI) where they reduce the spin–spin relaxation time (T₂-time) of absorbing tissue. Hence, control of their magnetic properties is essential for these applications. Magnetic properties strongly depend on the particle size and shape as well as the surface functionalization of the iron oxide nanoparticles. Especially, structural and magnetic disorder in the region close to the surface (1–2 nm) lead usually to a reduced magnetization compared to the corresponding bulk material. Therefore, X-ray magnetic circular dichroism (XMCD) in the total electron yield (TEY) mode is used to investigate local magnetic and electronic properties of the surface region of monodisperse, spherical FeO_<i>x</i>-NPs (Fe₃O₄/γ-Fe₂O₃) before and after the postsynthetic treatment in oxygen-rich environment. Charge transfer multiplet calculations of the XMCD spectra are performed to analyze the contributions of Fe²⁺ and Fe³⁺ at different lattice sites, i.e., either in octahedral or tetrahedral environment. The analysis of the XMCD data reveals that both, the magnetization of the nanoparticle surface region as well as their maghemite to magnetite ratio, are strongly increased after tempering in an oxidative environment, which likely causes rearrangement of their crystalline order. The magnitude and the kinetics of these variables depend strongly on the particle size. In addition, after thermal annealing a reduced spin canting is extrapolated from the lower magnetic coercivity, which confirms that a structural rearrangement takes place

Addressing adverse synergies between chemical and biological pollutants at schools—The ‘SynAir-G’ hypothesis

While the number and types of indoor air pollutants is rising, much is suspected but little is known about the impact of their potentially synergistic interactions, upon human health. Gases, particulate matter, organic compounds but also allergens and viruses, fall within the ‘pollutant’ definition. Distinct populations, such as children and allergy and asthma sufferers are highly susceptible, while a low socioeconomic background is a further susceptibility factor; however, no specific guidance is available. We spend most of our time indoors; for children, the school environment is of paramount importance and potentially amenable to intervention. The interactions between some pollutant classes have been studied. However, a lot is missing with respect to understanding interactions between specific pollutants of different classes in terms of concentrations, timing and sequence, to improve targeting and upgrade standards. SynAir-G is a European Commission-funded project aiming to reveal and quantify synergistic interactions between different pollutants affecting health, from mechanisms to real life, focusing on the school setting. It will develop a comprehensive and responsive multipollutant monitoring system, advance environmentally friendly interventions, and disseminate the generated knowledge to relevant stakeholders in accessible and actionable formats. The aim of this article it to put forward the SynAir-G hypothesis, and describe its background and objectives.Full text license: CC BY-NC-ND</p