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Paper des Monats
- ja (27)
Flow cytometry-based immunoassays are valuable in biomedical research and clinical applications due to their high throughput and multianalyte capability, but their adoption in areas such as food safety and environmental monitoring is limited by long assay times and complex workflows. Rapid, simplified bead-based cytometric immunoassays are needed to make these methods viable for point-of-need applications, especially with the increasing accessibility of miniaturized cytometers. This work introduces superparamagnetic hybrid polystyrene-silica core−shell microparticles as promising alternatives to conventional polymer beads in competitive cytometric immunoassays. These beads, featuring high specificity, sensitivity, and excellent handling capabilities via magnetic separation, were evaluated with three different antibodies and binding methods, showing variations in signal intensity based on the antibody and its attachment method. The optimal performance was achieved through a secondary antibody binding approach, providing strong and consistent signals with minimal uncertainty. The optimized protocol made it possible to achieve a detection limit of 0.025 nM in a total assay time of only 15 min and was successfully used to detect ochratoxin A (OTA) in raw flour samples. This work highlights the potential of these beads as versatile tools for flow cytometry-based immunoassays, with significant implications for food safety, animal health,
environmental monitoring, and clinical diagnostics.
Single-particle inductively coupled plasma-mass spectrometry (sp-ICP-MS) is one of the most powerful tools in the thriving field of nanomaterial analysis. Along the same lines, single-cell ICP-MS (sc-ICP-MS) has become an invaluable tool in the study of the variances of cell populations down to a per-cell basis. Their importance and application fields have been listed numerous times, across various reports and reviews. However, not enough attention has been paid to the immense and ongoing development of the tools that are currently available to the analytical community for the acquisition, and more importantly, the treatment of single-particle and single-cell-related data. Due to the ever-increasing demands of modern research, the efficient and dependable treatment of the data has become more important than ever. In addition, the field of single-particle and single-cell analysis suffers due to a large number of approaches for the generated data—with varying levels of specificity and applicability. As a result, finding the appropriate tool or approach, or even comparing results, can be challenging. This article will attempt to bridge these gaps, by covering the evolution and current state of the tools at the disposal of sp-ICP-MS users.
Graphical Abstract
The analysis of per- and polyfluoroalkyl substances (PFAS) via sum parameters like extractable organic fluorine (EOF) in combination with high resolution-continuum source-graphite furnace molecular absorption spectrometry (HR–CS–GFMAS) is highly promising regarding fluorine sensitivity and selectivity. However, the HR–CS–GFMAS method includes several drying and heating steps which can lead to losses of volatile PFAS before the molecular formation step using e.g., GaF formation. Hence, the method leads to a strong discrimination of PFAS within the EOF depending on their physical/chemical properties and is therefore associated with reduced accuracy. To reduce this discrepancy and to indicate realistic PFAS pollution values, an optimization of the HR–CS–GFMAS method for PFAS analysis is needed. Hence, we determined fluorine response factors of several PFAS with different physical/chemical properties upon application of systematic optimization steps. We could therefore improve the method's sensitivity for PFAS analysis using a modifier drying pre-treatment step followed by a sequential injection of sample solutions. The highest improvement in sensitivity of volatile PFAS was shown upon addition of a Mg modifier during drying pre-treatment. Thereby, during optimization the relative standard deviation of fluorine response factors could be reduced from 55 % (initial method) to 27 % (optimized method) leading to a more accurate determination of organofluorine sum parameters. The method provides an instrumental LOD and LOQ of β(F) 1.71 μg/L and 5.13 μg/L, respectively. Further validation aimed to investigate several matrix effects with respect to water matrices. Here, substance-specific behavior was observed. For example, perfluorooctanoic acid (PFOA) which was used as calibrator, showed signal suppressions upon high chloride concentrations (>50 mg/L). Hence, a thorough separation of Cl from analytes during sample preparation is needed for accurate sum parameter analysis.
Ytterbium-doped LiYF4 (Yb:YLF) is a promising material for all-solid-state optical cryocoolers, but the impact of foreign rare-earth impurities on the laser-cooling performance is not completely understood. In particular, Tm3+ has been reported to reduce the background absorption. This study quantitatively assesses the impact of Ho3+, Tm3+, and Er3+ impurities on laser-cooling of Yb:YLF by anti-Stokes fluorescence. We grew five Yb(5%):YLF crystals intentionally doped with tens of ppm levels of these impurities. Laser-induced thermal modulation spectroscopy tests confirmed that these rare-earth impurities reduce the external quantum efficiency of Yb:YLF without affecting the background absorption coefficient. Although Er3+ is a well-known quencher for Yb3+, Er3+ co-doping only slightly decreases the laser-cooling efficiency at low pump intensities but becomes detrimental at high pump intensities (>5 kW cm−2). However, this detrimental effect diminishes at lower temperatures, as evidenced by cooling an Er3+ co-doped crystal to the same minimum temperature of 144K as a solely Yb3+-doped crystal. Contrary to previous reports, Tm3+ proved to be the most detrimental among the three impurities.
Therapeutic monoclonal antibodies are the fastest-growing class of biological agents and the development of reliable analytical methods for their quantification is becoming increasingly important. Liquid chromatography coupled with tandem mass spectrometry (LC–MS/MS) represents one of the leading technologies for antibody quantification. The serin protease trypsin has emerged as the gold standard enzyme for digesting intact protein into peptides for this approach. However, many protocols exist that often lead to different results. The talk will provide a brief introduction to the application of novel thermostable and surface-functionalized trypsin particles for improved antibody digestion as well as initial successes in polymer functionalization of the corundum surface to prevent nonspecific protein adsorption during the digestion procedure.
Aktuelles aus der Normung
(2024)
Every day, there are new headlines in the media about microplastics (1-1000 µm, ISO/TR 21960:2020) and nanoplastics (< 1 µm, ISO/TR 21960:2020) findings all over the planet with high variations in particle number and mass. The challenges in analytics are very complex, e.g. representative sampling, non-destructive sample preparation with concentrated particles and homogeneous distribution and true detection. All together lead to lacks in harmonization and results, which are hardly comparable. On the other hand, monitoring of microplastics is mandatory in the future strictly regulated by the EU commission in the Drinking water and Wastewater Framework Directive. One step to accurate and precise results will be the development of suitable reference materials mimicking particles in the environment.
BAM developed test materials, which are produced by mixing a small portion of microplastic particles with a water-soluble matrix. After solid phase dilution and homogenisation small portions are pressed into tablets and bottled in glass vials (Figure 1). These tablets are well characterized with particle size distribution and SEM images. Additionally, they are tested as reference material candidate according to homogeneity and stability for particle number with µ-IR and µ-Raman as well as on particle mass with Py-GC/MS and TED-GC/MS after ISO Guide 35. Results are promising. The material passed the homogeneity control. No changes are observed within 6 months of storage.
The same tested reference material is finally used in sample preparation experiments, where environmental suspended particular matter from surface water or baby milk powders are spiked with the tablets.
Over the last 20 years, many researchers, politicians and citizens have become increasingly aware of the growing plastic problem of our time. A lack of recycling concepts and plastic collection points as well as careless dumping lead to accumulation of plastic products in the environment. Natural weathering can cause these plastics to degrade and fractionate, meaning that microplastics (1 1,000 µm, ISO/TR 21960:2020) and nanoplastics (< 1 µm, ISO/TR 21960:2020) of various synthetic polymer materials can now be detected in all parts of the world. Whether microplastics or nanoplastics pose a toxicological hazard is being investigated in a variety of ways. Valid results are still pending. However, the EU precautionary principle applies to micro- and nanoplastics. Monitoring of microplastics is already required in the revision of the Drinking Water and Wastewater Framework Directive.
Reliable monitoring of rivers can be carried out by sampling with sedimentation boxes and microplastic detection by using thermal extraction desorption gas chromatography/mass spectrometry (TED-GC/MS) in routine operation (Figure 1). The river Rhine was sampled for microplastic masses at three different sampling locations over a period of one year and in addition the Danube at randomized sampling locations The TED-GC/MS results showed that various synthetic polymers frequently produced in industry, such as polyethylene, polypropylene or polystyrene as well as the tire compound styrene-butadiene rubber were found. The work not only shows a possible workflow for monitoring concepts, but also provides information on environmentally relevant concentrations of microplastics and tire components in surface waters. This in turn is necessary for ecotoxicological studies.
Die Gruppe der PFAS (Per- und polyfluorierte Alkylsubstanzen) mit mehr als 10.000 Substanzen stellt ein zunehmendes Problem bei der Bewertung und Entsorgung belasteter Abfälle dar. Die zuverlässige PFAS-Analytik stellt hier aufgrund der Vielzahl an Einzelparametern mit zum Teil sehr großen Konzentrationsunterschieden eine komplexe Herausforderung dar.
Der Vortrag gibt zunächst einen Überblick über grundlegende Anforderungen an die LC-MS/MS Analytik von PFAS-Targetsubstanzen. Am Beispiel eines von BAM und SenMVKU organisierten Ringversuches 2024 zur Bestimmung von PFAS in Bodenproben (Feststoffe und Eluate) wird auf spezifische Fragestellungen zur PFAS-Analytik eingegangen.
Zur Verbesserung von Richtigkeit und Vergleichbarkeit ist die Einhaltung von Normvorgaben und die Anwendung von Qualitätssicherungsmaßnahmen unerlässlich. Hierzu gehören u.a. die Verwendung zuverlässiger Kalibrierstandards, die Kalibrierung mit definierten n-Isomeren, die Quantifizierung der Summe aus n-/br-Isomeren, der Einsatz isotopenmarkierter interner Standards für die LC-MS/MS Analyse, die Verwendung von Matrix-Referenzmaterialien sowie die Teilnahme an Ringversuchen.
Germany has set itself the task to become a world leader in the field of green hydrogen technologies and is promoting the transition to a hydrogen economy. The H2Mare flagship project is exploring the offshore production of green hydrogen and other power-to-X products. One of the most important goals is the safe and cost-efficient operation of offshore infrastructures, where a service life of at least 25 years is aimed. However, the corrosive environment towards metallic materials presents challenges in marine areas. The atmosphere at one location could be affected by the distance to the sea level and does not have the same corrosivity for all exposed kinds of materials. The creation of an atmosphere corrosion atlas for marine environments by weathering campaigns aims to close this gap. Operators of offshore structures can use the data to estimate the corrosivity of the atmosphere on the construction site. This allows planning to be optimized in terms of platform safety as well as maintenance costs.
An accurate measurement of the amount fraction of hydrogen in gas mixtures is mandatory for practical applications, requiring methods that are fast, continuous, robust, and cost-effective. This study compares the performance of Raman and benchtop NMR process spectroscopy for determining the hydrogen amount fraction in gas mixtures. A setup was designed to integrate both techniques, enabling measurements of the same sample.
Tests were conducted with gravimetrically prepared gas mixtures of reference quality ranging from 1.20 cmol/mol to 85.83 cmol/mol of hydrogen. The results demonstrate that Raman spectroscopy provides superior performance, with a minimal root mean square error (RMSE) of 0.22 cmol/mol and excellent linearity. In contrast, benchtop NMR spectroscopy faced challenges, such as overlapping peaks and longer measurement times, resulting in a higher RMSE of 0.71 cmol/mol. Raman spectroscopy proves to be particularly well-suited for
practical applications due to its high accuracy and linearity. Meanwhile, benchtop NMR spectroscopy holds potential for future enhancements through ongoing technological advances, such as higher magnetic field strengths. In summary, the results from our study indicate that Raman spectroscopy is already a serviceable method for precise hydrogen quantification, whereas benchtop NMR spectroscopy can be attributed potential for future applications.
In den deutschen Zulassungen für Gefahrgutverpackungen muss der minimale Schüttwinkel angegeben werden, für den die Verpackung verwendet werden darf. Dieser fungiert als Maß für die Fließeigenschaften pulverförmiger oder körniger Stoffe und ist wichtig für die Sicherheit beim Gefahrguttransport. In den Prüfstellen existiert jedoch eine Reihe von Messmethoden für diese Kenngröße. In der Vergangenheit war hierbei unklar, welche dieser Methoden für welche Prüffüllgüter prinzipiell geeignet sind. Die BAM nahm dies zum Anlass, die gebräuchlichen Messmethoden systematisch zu untersuchen. Dieser Artikel gibt einen Gesamtüberblick über die Ergebnisse und stellt die Schlussfolgerungen für die Prüfpraxis in den anerkannten Prüfstellen für Gefahrgutverpackungen dar.
Die Fließeigenschaften fester Gefahrgüter spielen für die Sicherheit beim Gefahrguttransport eine wichtige Rolle. Diese haben einen Einfluss sowohl auf die mechanische Sicherheit der verwendeten Verpackung als auch auf die Freisetzung fester Substanzen unter normalen Beförderungsbedingungen aufgrund ungenügender Staubdichtheit. Bei festen Gefahrgütern kann es sich entweder um pulverförmige oder um körnige Stoffe handeln. Um der sicherheitsrelevanten Bedeutung der Fließeigenschaften fester Füllgüter Rechnung zu tragen, muss in den deutschen Zulassungen für Gefahrgutverpackungen der minimale Schüttwinkel angegeben werden, für welche die Verpackung verwendet werden darf. In der Praxis der Prüfstellen existiert jedoch eine Reihe von Messmethoden für diese Kenngröße. In der Vergangenheit war hierbei unklar, welche dieser Methoden für welche Prüffüllgüter prinzipiell geeignet sind. Es ist jedoch essenziell, die Vor- und Nachteile sowie die Grenzen der einzelnen Verfahren zu kennen. Dieser Artikel gibt eine Einführung in die Thematik und in experimentelle Untersuchungen, die in der BAM durchgeführt wurden, um eine Klärung herbeizuführen. Die Ergebnisse dieser Versuche werden in einem Folgeartikel vorgestellt.
Im November 2019 wurde der Entwurf der VDI-Richtlinie 3783 Blatt 1 „Ausbreitung von störungsbedingten Freisetzungen“ als Gründruck veröffentlicht.
Neben den Einsprüchen zur Richtlinie in Bezug auf unklare Formulierungen, wurde oft das Fehlen eines Referenzprogramms, als auch die Abkehr vom etablierten Gauß-Wolken-Modell bemängelt.
Im Rahmen der darauffolgenden Überarbeitung des Richtlinienentwurfs wurde ein Gauß-Wolken-Modell entwickelt, das mit einem geringen Rechenaufwand in einem begrenzten Anwendungsbereich mit dem Lagrange’schen Partikelmodell vergleichbare Berechnungsergebnisse liefert.
Darüber hinaus wurden Empfehlungen zur praktischen Umsetzung von Szenarien in den neuen Richtlinienentwurf, der voraussichtlich im Oktober 2024 als Gründruck vorliegt, aufgenommen.
Quantum dots (QDs) possess unique optoelectronic properties, which make them very attractive to be used as optical probes in biosensing and bioimaging applications. The strong absorbance and light scattering of biological compounds like tissue and blood in the visible range pose a problem. However, if optical probes emitting in the near-infrared (NIR) range are used, scattering, absorption, and autofluorescence of biological components are strongly reduced. This allows for an increased light penetration depth and higher spatial and temporal resolution for the investigation of biological processes. The synthesis and application of NIR emitting QDs is a fast-growing research field and the benefits of using QDs were demonstrated for a variety of applications, such as photoelectrochemical biosensor, in vivo vascular imaging, and fluorescence-guided surgery. This article reviews the state-of-the-art developments in the preparation of NIR/IR QDs and highlights the latest research about their utilization in biosensing and bioimaging applications.
Die Gefährdungen durch die Freisetzung von Gasen und Dämpfen infolge der Ableitung über Ausbläser aus Sicherheitsventilen, Prozess-Berstscheiben, Entlüftungs- und Entspannungsleitungen sind in einer Gefährdungsbeurteilung zu bewerten. Freisetzungen aus Druckanlagen können nach TRBS 2141 beurteilt werden.
In der Fachbereich AKTUELL werden verschiedene Methoden mit ihren benötigten Eingangsdaten und Anwendungsgrenzen zur Beurteilung der Gefahren an Ausbläsern für brennbare Gase vorgestellt, um den Anwendern und Prüfern von solchen Anlagen eine Hilfestellung bei der Bewertung und Beurteilung möglicher Gefahren an den prozessbedingten Stoffauslässen ins Freie zu geben.
The analysis of the presence and content of substances that are toxic to aquatic life in waste is essential for classification of waste with regard to hazard property (HP) 14 ‘ecotoxic’. For the determination of HP14 classified copper (Cu) and zinc (Zn) compounds in various municipal solid waste incineration bottom ashes (IBA) and one fly ash (FA) from Germany we applied X-ray absorption near-edge structure (XANES) spectroscopy in combination with linear combination fitting. The analysis showed that approx. 50–70% of Cu in the IBA are Cu(I) compounds and elemental Cu(0), but these compounds were not equally distributed in the different IBA. In contrast, the majority (approx. 50–70%) of Zn in all IBA is elemental zinc, which originates from brass or other alloys and galvanized metals with a large content of zinc in the waste. The FA contain higher mass fraction on Zn and other toxic elements, but similar Cu and Zn species. Additional performed selective extraction at a pH of 4 with an organic acid of some IBA showed that the ecotoxic Zn fraction is mainly elemental zinc and zinc oxide. In contrast, for the ecotoxic Cu fraction within the IBA no specific compound could be identified. Furthermore, the XANES analysis showed that the HP14 properties of especially Cu in IBA is overestimated with current best-practice guidelines for sample processing for the current substance-related approach with the 0.1% cut-off rule for each substance. However, it should be considered whether it would not be better from an environmental point of view to take the ecotoxicologically leachable copper and zinc as a reference value.
Atmospheric deposition of particulate matter is an important indicator of air pollution and a significant factor in material surface fouling. The elemental composition of this nutrient-containing dust depends largely on the exposure region and time as well as on climate. Therefore, in this paper we report an analysis of atmospheric pollutions with a self-made low-cost bulk deposition sampler directed at sampling deposition via air transport and rainfall. We used the device in diverse environments - thus comparing an urban region, an area surrounded by forest and an area mainly dominated by agriculture. The total organic carbon (TOC) and total nitrogen (TN) amounts were selected as indicator parameters and analyzed in a biweekly rhythm for three and a half and two years, respectively. The TOC value responded to particulate matter in the urban area, especially significant were the influences of the New Year's firework in urban and pollen in the rural forest area. In contrast, the TN value was more under the influence of the nitrogen emissions in the agriculture-dominated area. However, the TN value did not correlate with the NOx values in the urban area because the atmospheric nitrogen emissions in the city might originate from various emission sources. Summarizing, the TOC and TN values of the self-made low-cost bulk deposition sampler were in good agreement with environmental events of their immediate surrounding. Moreover, the selected containers and sampling procedures are universally applicable to monitor and analyze organic as well as inorganic parameters (e.g. metal ions) of atmospheric deposition.
Quinone dioxime - QDO
(2024)
Der Vortrag beschreibt die Eigenschaften und die Einstufung von QDO. Die Prüfergebnisse sind nicht frei zugänglich. Der Vortrag wurde im Kreis der international zuständigen Behörden gehalten.
Eurachem is an international network of national organisations having the objective of establishing a system for the international traceability of chemical measurements and the promotion of good quality practices. It also provides a forum for discussing common problems and exchanging information on quality assurance issues in analytical chemistry. The presentation will explain how Eurachem is organised, the requirements for participation and the opportunities for collaboration and networking. In particular, it will discuss why Eurachem offers an interesting network for young scientists to exchange experiences and further their own education.
Die Erforschung des Proteoms, der Gesamtheit der Proteine eines Lebewesens, ist von großer Bedeutung für das Verständnis biologischer Systeme. Aufgrund dessen ist die Proteomik ist eines der bedeutendsten aktuellen Forschungsfelder der Biowissenschaften. In der Bottom-Up-Proteomik werden die Proteine einer Probe vor ihrer Analyse einem enzymatischen Verdau mit Proteasen unterzogen, was eine erleichterte Analyse mit hohem Durchsatz ermöglicht. Aufgrund seiner hohen Aktivität und Effektivität hat sich die Serinprotease Trypsin als Standard-Enzym der Proteomik etabliert. Die weitere Verbesserung ihrer Enzymcharakteristika, wie Thermostabilität und Aktivität, ist unter anderem durch Immobilisierung an ein Trägermaterial oder genetische Modifikation möglich. In der vorliegenden Arbeit wurde eine von Xiao et al. 2023 entwickelte thermostabile Trypsin-Variante mit erhöhter Oberflächen-Hydrophobizität rekombinant in E. coli hergestellt und sowohl immobilisiert als auch in Lösung hinsichtlich ihrer Enzymaktivität und Thermostabilität im Vergleich zum Wildtyp charakterisiert. Die vorliegende Arbeit stellt dabei eine Erstbeschreibung der Immobilisierung einer thermostabilen Trypsin-Spezies an ein Trägermaterial dar und untersucht somit erstmalig das Zusammenspiel der beiden Optimierungsstrategien Immobilisierung und genetische Modifikation.
Das thermostabile Trypsin und sein Wildtyp wurden rekombinant als Zymogene hergestellt, wobei trotz verschiedener Strategien zum Erhalt der nativen Konformation, wie der Fusion mit dem Chaperon-ähnlichen Maltose-bindenden Protein (MBP), eine starke Aggregation in Einschlusskörperchen (inclusion bodies, IB) erfolgte. Im Zuge der Rückfaltung der fehlgefalteten Proteine wurden verschiedene Rückfaltungsbedingungen untersucht, wobei die Vorteile einer langsamen Absenkung des Gehalts der Denaturierungsreagenz in Kombination mit einem Cystein-Cystine- Redoxsystem dargelegt werden konnten. Es konnte keine Verbesserung der Aktivität und Thermostabilität des genetisch modifizierten Enzyms in freier Form festgestellt werden, jedoch eine erhöhte Substrataffinität. Durch Immobilisierung an Magnetbeads mit tosylfunktionalisierter Oberfläche konnte die Enzymaktivität der genetisch modifizierten Trypsin-Variante bei 80 °C vollständig erhalten werden, während die Aktivität des Wildtyps verringert wurde. Dies legt nahe, dass die erhöhte Oberflächen-Hydrophobizität der modifizierten Trypsin-Variante zu einer erhöhten Bindung an das Trägermaterial beiträgt, was eine Verbesserung der Stabilität bei thermischer Erhitzung bewirkt.
This talk presents the EU funded project PlasticTrace. It shows the challenges in micro- and nanoplastic reference materials and gives some solutions regarding spectroscipc methods such as Raman or IR microscopy to determine the particle numbers. Materials are prepared by cryo milling to get some powder that is later pressed into tablets. The polymer type used is PET, because that is highly important for drinking water directive of EU commission.
Many organisations are being driven towards employing sustainable practices to counteract the growing concerns of environmental and social issues. With various stakeholders including governments, suppliers and customers putting on pressure the process industry is no exception. However, many industrial firms struggle to implement sustainability measures. One of the usual first steps when conducting implementation is to analyse the current situation. For this analysis, indicators are commonly used to measure, monitor, and report a company’s sustainable development performance. However, the selection of appropriate indicators is often challenging due to the current lack of relevant methodologies, guidelines, and insights into a practitioner perspective.
To address this challenge, this work focuses on the creation of a user-orientated method, which helps practitioners in the process industry to select relevant indicators for their plant and assist in the deduction of sustainability measures. This includes addressing the difficulties of implementation and regarding the current needs like the inclusion of indicators for reporting or the quantification of gathered metrics.
The presentation is divided into two parts. The first part is about the influence of the oxygen content to results testing the oxygen compatibility. BAM performed tests with several nonmetallic sealing materials such as PTFE, PA 6.6, and EPDM with different oxygen contents between 21 Vol% and pure oxygen. Using the standardized oxygen pressure surge tester, the results have shown, that even a small increase in the oxygen content above 21% in air is associated with a significant reduction on the maximum test pressure at which no reaction of the material occurs. Using the standardized tester to determine the autogenous ignition temperature of the materials in oxygen, the results have shown, that even a small increase in the oxygen content above 21% in air is associated with a significant reduction on the autogenous ignition temperature at which the material shows self-ignition without an additional ignition source. The second part of the presentation is about the oxygen endurance test according to DIN EN ISO 10297, which is generally performed with air or with nitrogen. However, BAM performed this test with oxygen. In some cases, different test results were found: Valves failed the endurance test with oxygen but passed the endurance test with air. Based on the results with different oxygen content and with the oxygen endurance tester, it is unclear, why materials and valves for oxygen are still not consistently tested with oxygen.
Motivation: A precise diagnosis of atherosclerosis is of clinical importance, since cardiovascular disease remain one of the leading causes of death worldwide.
Goal(s): The goal of this study was to evaluate the feasibility of characterizing a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS4) using molecular magnetic resonance imaging in a preclnical model of atherosclerosis.
Approach: Molecular magnetic resonance imaging using a novel probe targeted against ADAMTS4 was used in a high-fat murine model.
Results: It was possible to image atherosclerotic lesions in a mouse model using an ADAMTS4- specific probe for magnetic resonance imaging.
Impact: Using molecular MRI targeting ADAMTS4 is a promising method for characterization of plaque composition and could possibly impact plaque vulnerability assessment in the diagnosis and treatment of atherosclerosis in patients.
Non‐targeted screenings (NTS) are essential tools in different fields, such as forensics, health and environmental sciences. NTSs often employ mass spectrometry (MS) methods due to their high throughput and sensitivity in comparison to, for example, nuclear magnetic resonance–based methods. As the identification of mass spectral signals, called annotation, is labour intensive, it has been used for developing supporting tools based on machine learning (ML). However, both the diversity of mass spectral signals and the sheer quantity of different ML tools developed for compound annotation present a challenge for researchers in maintaining a comprehensive overview of the field.In this work, we illustrate which ML‐based methods are available for compound annotation in non‐targeted MS experiments and provide a nuanced comparison of the ML models used in MS data analysis, unravelling their unique features and performance metrics. Through this overview we support researchers to judiciously apply these tools in their daily research. This review also offers a detailed exploration of methods and datasets to show gaps in current methods, and promising target areas, offering a starting point for developers intending to improve existing methodologies.
The gravimetric isotope mixture method is the primary method to determine absolute isotope ratios. This method, however, depends on the existence of suitable spike materials and knowledge of their purities. Determining the purity of the spikes can be tedious and labour-intensive. In this publication, an advancement of the gravimetric isotope mixture method, rendering the determination of the purity of the spike materials unnecessary, is presented. The advancement combines mass spectrometry and ion chromatography leading to an approach being independent of the purity of the spike materials. In the manuscript the mathematical background and the basic idea of the novel approach are described using a two-isotope system like copper or lithium.
Fenton-like processes using persulfate for oxidative water treatment and contaminant removal can be enhanced by the addition of redox-active biochar, which accelerates the reduction of Fe(III) to Fe(II) and increases the yield of reactive species that react with organic contaminants. However, available data on the formation of non-radical or radical species in the biochar/Fe(III)/persulfate system are inconsistent, which limits the evaluation of treatment efficiency and applicability in different water matrices. Based on competition kinetics calculations, we employed different scavengers and probe compounds to systematically evaluate the effect of chloride in presence of organic matter on the formation of major reactive species in the biochar/Fe(III)/persulfate system for the transformation of the model compound N,N‑diethyl-m-toluamide (DEET) at pH 2.5. We show that the transformation of methyl phenyl sulfoxide (PMSO) to methyl phenyl sulfone (PMSO2) cannot serve as a reliable indicator for Fe(IV), as previously suggested, because sulfate radicals also induce PMSO2 formation. Although the formation of Fe(IV) cannot be completely excluded, sulfate radicals were identified as the major reactive species in the biochar/Fe(III)/persulfate system in pure water. In the presence of dissolved organic matter, low chloride concentrations (0.1 mM) shifted the major reactive species likely to hydroxyl radicals. Higher chloride concentrations (1 mM), as present in a mining-impacted acidic surface water, resulted in the formation of another reactive species, possibly Cl2•−, and efficient DEET degradation. To tailor the application of this oxidation process, the water matrix must be considered as a decisive factor for reactive species formation and contaminant removal.
This research group has been demonstrating the significant advantages of using Nb2O5 coatings for functionalizing titanium, aluminium, and stainless steels. Regarding the biomedical sector and considering Ti-6Al-4V alloy, the reactive sputtering technique improved the cell viability, the osteogenic performance of cells involved in the osseointegration process as well as the ability to delay bacterial proliferation. The characteristics of the Nb2O5 coatings were assessed before by using standard methods, which provide information only a few tens of nanometers depth. Given that the Nb2O5 coating fabricated in this work exhibits a thickness of approximately 300 nm, the GE-XANES technique emerges as the most suitable method for this analysis. Additional information was provided with the aid of nanoindentation load-depth (P-h) curves. GE-XANES results indicated the formation of a homogeneous layer of Nb2O5 coating on the Ti-6Al-4V surfaces. The deposition process improved the surface hardness of the Ti-6Al-4V alloy (4.38 GPa versus 5.62 GPa) considering the 2 mN load.
The nature of the support can fundamentally affect the function of a heterogeneous catalyst. For the novel type of isolated metal atom catalysts, sometimes referred to as single‐atom catalysts, systematic correlations are still rare. Here, we report a general finding that Pd on nitride supports (non‐metal and metal nitride) features a higher oxidation state compared to that on oxide supports (non‐metal and metal oxide). Through thorough oxidation state investigations by X‐ray absorption spectroscopy (XAS), X‐ray photoelectron spectroscopy (XPS), CO‐DRIFTS, and density functional theory (DFT) coupled with Bader charge analysis, it is found that Pd atoms prefer to interact with surface hydroxyl group to form a Pd(OH)x species on oxide supports, while on nitride supports, Pd atoms incorporate into the surface structure in the form of Pd−N bonds. Moreover, a correlation was built between the formal oxidation state and computational Bader charge, based on the periodic trend in electronegativity.
Iodine is an essential trace element in the human diet because it is involved in the synthesis of thyroid hormones. Iodine deficiency affects over 2.2 billion people worldwide, making it a significant challenge to find plant-based sources of iodine that meet the recommended daily intake of this trace element. In this study, cabbage plants were cultivated in a hydroponic system containing iodine at concentrations ranging from 0.01 to 1.0 mg/L in the form of potassium iodide or potassium iodate. During the experiments, plant physiological parameters, biomass production, and concentration changes of iodine and selected microelements in different plant parts were investigated. In addition, the oxidation state of the accumulated iodine in root samples was determined. Results showed that iodine addition had no effect on photosynthetic efficiency and chlorophyll content. Iodide treatment did not considerably stimulate biomass production but iodate treatment increased it at concentrations less than 0.5 mg/L. Increasing iodine concentrations in the nutrient solutions increased iodine content in all plant parts; however, the iodide treatment was 2–7 times more efficient than the iodate treatment. It was concluded, that iodide addition was more favourable on the target element accumulation, however, it should be highlighted that application of this chemical form in nutrient solution decreased the concetrations of selected micoelement concentration comparing with the control plants. It was established that iodate was reduced to iodide during its uptake in cabbage roots, which means that independently from the oxidation number of iodine (+ 5, − 1) applied in the nutrient solutions, the reduced form of target element was transported to the aerial and edible tissues.
Colloids provide manifold opportunities for targeted product design due to their tunable properties with respect to size, shape, composition, surface, and spectral characteristics. However, the determination of structure-property relationships is quite challenging as most particulate samples exhibit polydispersity of their disperse properties. Analytical ultracentrifugation (AUC) is a fractionating technique and highly accurate method for the multidimensional analysis of nanoparticles as it permits the differentiation of spectral information linked to hydro- and thermodynamic properties of the particles.
So far, characterization capabilities for fluorescent nanoparticles by AUC were limited, as the formerly commercially available fluorescence detector could not provide any spectral information. Using a multiwavelength emission detector developed in our group, it is possible to extract spectra of fluorescent particles and biomolecules alongside their sedimentation and diffusion coefficients within a single centrifugation experiment.
In our contribution, we will highlight that even narrowly distributed core/shell CdSe/CdS quantum dots still show size- and structure-dependent shifts of their fluorescence spectra, which can be resolved with our AUC system in an ensemble measurement. Thereby, we can link spectral changes of only a few nanometers to particle sizes retrieved with Angstrom size resolution. Single-particle measurements not only supported the results obtained with the AUC system but also provided deeper insights into the photophysical processes of individual QDs, clearly demonstrating the complementary nature of the techniques used. With our novel multiwavelength emission detector and the established extinction-based detector for AUC, a comprehensive platform for the holistic characterization of fluorescent colloids is now available.
One remaining handicap for spatially resolved elemental quantification in biological samples is the lack of a suitable internal standard (IS) that can be reliably measured across both calibration standards and samples. In this work, multielement quantitative intracellular imaging of cells tagged with lanthanide nanoparticles containing key lanthanides, e.g., Eu and Ho, is described using a novel strategy that uses the ratio of IS elements and LA-ICP-TOFMS analysis. To achieve this, an internal standard layer is deposited onto microscope slides containing either gelatin calibration standards or Euand Ho-tagged cell samples. This IS layer contains both gallium (Ga) and indium (In).
Monitoring either element as an IS individually showed significant variability in intensity signal between sample or standards prepared across multiple microscope slides, which is indicative of the difficulties in producing a homogeneous film at intracellular resolution.
However, normalization of the lanthanide signal to the ratio of the IS elements improved the calibration correlation coefficients from 0.9885 to 0.9971 and 0.9805 to 0.9980 for Eu and Ho, respectively, while providing a consistent signal to monitor the ablation behavior between standards and samples. By analyzing an independent quality control (QC) gelatin sample spiked with Eu and Ho, it was observed that without normalization to the IS ratio the concentrations of Eu and Ho were highly biased by approximately 20% in comparison to the expected values.
Similarly, this overestimation was also observed in the lanthanide concentration distribution of the cell samples in comparison with
the normalized data.
Der Band 5 der N.i.Ke.-Schriftenreihe präsentiert den aktuellen Stand materialwissenschaftlicher und bildgebender Verfahren, die bei der Untersuchung von Zeichnungen Anwendung finden. Im ersten Teil der Publikation werden die klassischen Zeichnungsträger und Zeichnungsmaterialien vorgestellt. Der mittlere Teil der Publikation beschreibt die relevanten materialwissenschaftlichen und bildgebenden Verfahren. Der letzte Teil diskutiert anhand einiger Fallbeispiele die Möglichkeiten und Grenzen der Methoden.
Inorganic and organic functional nanomaterials (NM) of different size, shape, chemical composition, and surface chemistry are relevant for many key technologies of the 21st century. Decisive for most applications of NM are their specific surface properties, which are largely controlled by the chemical nature and number of ligands and functional groups (FG on the NM surface. The surface chemistry can strongly affect the physicochemical properties of NM, their charge, hydrophilicity/hydrophobicity, reactivity, stability, and processability and thereby their impact on the environment and biological species as well as their possible risk for human health. Thus, reliable, validated, and eventually standardized analytical methods for the characterization of NM surface chemistry, i.e., the chemical identification, quantification, and accessibility of FG and surface ligands 1,2] flanked by interlaboratory comparisons, control samples, and reference materials, 2 ,3 are of considerable importance for process and quality control of NM production and function. This is also important for the safe use of NM the design of novel NM, and sustainable concepts for NM fabrication. Here, we provide an overview of analytical methods for FG analysis and quantification and highlight method and material related challenges for selected NM. Analytical techniques address ed include electrochemical titration methods, optical assays, nuclear magnetic resonance (NMR) and vibrational (IR) spectroscopy, and X ray based and thermal analysis methods. Criteria for method classification and evaluation include the need for a signal generating label, provision of either the total or derivatizable number of FG, and suitability for process and production control.
The use of proton-transfer-reaction mass spectrometry (PTR-MS) for the determination of formaldehyde, ammonia and volatile sulfur organic compounds is described and suggestions are made for the application of stationary PTR-MS in a test laboratory. One advantage of PTR-MS compared to TD-GC-MS (thermal desorption gas chromatography mass spectrome-try) is the faster online measurement. Another advantage is the simultaneous determination of formaldehyde, ammonia, very volatile organic compounds (VVOC) and volatile organic com-pounds (VOC) which normally needs four different kinds of sampling. Coupling the PTR-MS with (multiple) air sample canisters or (multiple) emission test chambers would enable a quick analysis of indoor air and material emissions.
The Jack Rabbit II (JR II) chlorine field trials in 2015 and 2016 involved nine 5–20 ton releases of pressurized liquefied chlorine from a tank mounted 1 m above a broad flat desert sand surface. A model comparison study was initiated, where 17 widely-used dense-gas dispersion models were run by scientists in seven countries. Predictions were submitted following specified formats, using specified emissions and meteorology inputs. To compare with the model predictions, sets of observations were defined for the arc-maximum 1–3 s averaged concentrations (arc max C) and for cloud widths and heights (to 20 ppm and 200 ppm contours) at distances from 0.2 to 11.0 km from the release. The initial focus is on the three field trials (1, 6, and 7) that have the highest observed concentrations and that have detailed emissions information. It is found that these models are able to satisfactorily simulate (generally within a factor of two) the observed arc max C's and their variation with downwind distance at this flat desert site. At each downwind distance, the scatter in the arc max C predictions covers about 1 ½ orders of magnitude, but the observed arc max C is within the range of the predictions. The median of the cloud width predictions is about 50% larger than the observed value for the three trials. The median of the cloud height predictions is within about 10% of the observed value. For both cloud width and/or height, there are a few models with large (factor of 3 or higher) overpredictions. Of the 17 models, when compared to observations, there is a core group of 5 or 6 with consistently (across all three trials and all distances) less mean error and scatter in their predictions of arc max C and cloud width and height. However, as a group, the 17 models are performing adequately (using the “factor of two” rule of thumb). An important caveat is that, at the JR II desert site, chlorine deposition is minimal. At a site with vegetation and/or organic-rich soil, the effects of removal of chlorine by deposition are expected to be significant.
Alcohol-initiated polymerizations of glycolide (GL) catalyzed by tin(II) 2-ethylhexanoate (SnOct2) were carried out in bulk with variation of GA/In ratio, temperature and time. Due to a rather strong competition of cyclization polyglycolide (PGA) free of cycles were never obtained. When the cyclic catalysts 2,2-dibutal-2-stanna − 1,3-dithiolane (DSTL) or 2-stanna 1,3-dioxo-4,5,6,7 bibenzepane (SnBiph) were used in combination with 1,4-butanediol the influence of cyclization was even stronger. Furthermore, the degrees of polymerization were higher than the GA/alcohol ratio due to rapid polycondensation in the solid state. At 160 °C or below, the matrixassisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectra indicated separate crystallization of low molar mass cyclic and linear PGAs from the same reaction mixture (also observed for poly(L-lactide)s).
A journey in science from a graduate student in physical chemistry to head of division biophotonics
(2024)
I will provide a personal overview of the most important steps of my career in science, a journey from a graduate student in physical chemistry in an environment dominated by male-scientists over a postdoc with a female professor in the US to the leader of a research group, head of division Biophotonics at BAM. This will include my choices of research topics, how I learnt to write well cited publications, even on topics such as reference materials and quality assurance,1-4 and eventually started to give lectures at Free University Berlin granting me the right to act as first supervisor of undergraduate and graduate students.
Reducing the size of upconversion nanoparticles (UCNPs) down to a few nm yields luminescent materials containing a very small number of emitters.
Considering the bottom limit of one activator per particle ultrasmall UCNPs offer an unprecedented platform to study the contributions of the energy transfers at play in upconversion luminescence. Maintaining detectable emission despite the limited number of emitting ions and the high surface-to-volume ratio requires suitable particle architectures.
Na(Gd-Yb)F4:Tm3+ emissive sub-3 nm diameter 𝜷-phase UCNPs are prepared using a gadolinium-rich composition in situ mixing of the precursors and a microwave high-temperature cycling sequence allowing precise control of the particle size and dispersity. These cores are coated with a NaGdF4 inert shell to minimize the deleterious influence of surface quenching (SQ).
Time-resolved luminescence measurements combining standard NIR excitation of the Yb3+ sensitizer and direct UV excitation of the Tm3+ activator are performed to quantify cross relaxation and surface quenching processes.
The fine tuning of the number of activators per particle via an optimized synthesis pathway along with the use of an appropriate excitation scheme enabled to provide an accurate analysis of the different mechanisms at play in these model nanoparticles and to characterize the structure of the core-shell architecture.
Der Arbeitsschwerpunkt „Sauerstoff“ des Fachbereichs 2.1 ist v.a. durch seine wissenschaftlich-technischen Tätigkeiten und seine Einnahmen aus Dienstleistungsvorgängen geprägt und bekannt. Die Durchführung standardisierter und nichtstandardisierter Prüfungen zur Untersuchung der Eignung nichtmetallischer Materialien sowie die Prüfung auf Ausbrennsicherheit von Armaturen und Anlagenteilen für den Einsatz in Sauerstoff stellen einen Großteil der Tätigkeiten und Arbeiten dar. Weit weniger bekannt sind die Forschungsaktivitäten des Arbeitsschwerpunkts, von denen drei Beispiele in diesem Vortrag kurz vorgestellt werden:
Die in Normen für Druckstoßprüfungen festgelegte Sauerstofftemperatur beträgt bei den nichtmetallischen Materialien 60 °C, bei den Armaturen aber 65 °C. Seit mehr als zwei Jahren werden nunmehr systematische Untersuchungen durchgeführt, ob dieser Temperaturunterschied zu signifikanten Unterschieden bei den Prüfergebnissen der nichtmetallischen Materialien führt. Ziel ist es, einerseits den Prüfaufwand zu optimieren und andererseits die entsprechenden Normen zu harmonisieren.
Es ist bekannt, dass Bearbeitungsverfahren, Probenvorbereitung und Vorkonditionierung einen Einfluss auf die Eignung nichtmetallischer Materialien für den Einsatz in Sauerstoff haben können. Anhand einer Charge eines Referenzmaterials werden diese möglichen Einflussfaktoren in Kooperation mit industriellen Partnern systematisch untersucht. Ziel hierbei ist es, unterschiedliche Prüfergebnisse einer Materialcharge zu erklären, die kritischsten Prüfbedingungen herauszufinden und Möglichkeiten der Übertragbarkeit von Prüfergebnissen auszuloten.
Wasserstoff gilt als zukunftsweisender Energieträger, der bei der Elektrolyse von Wasser anfallende Sauerstoff soll dabei ebenfalls genutzt werden. Die Anforderungen an die eingesetzten Materialien (Kombination aus niedrigem Druck, hohem Wasserdampfanteil im Sauerstoff und hoher Temperatur) führen dazu, dass bestehende und bewährte Prüfeinrichtungen modifiziert werden müssen. Im Rahmen BAM-interner Forschungsvorhaben und mit Unterstützung industrieller Partner wurde damit begonnen, die Zündtemperaturbestimmung sowie die Untersuchung des Alterungsverhaltens nichtmetallischer Materialien in Wasserdampf-gesättigtem Sauerstoff zu untersuchen
L-Lactide (LA) was polymerized with neat tin(II) 2-ethylhexanoate (SnOct2) in toluene at 115 °C at low concentration with variation of the LA/Cat ratio. Cyclic polylactides (cPLAs) with number average molecular weights (Mn) between 7 000 and 17 000 were obtained. MALDI-TOF mass spectrometry also revealed the formation of a few percent of linear chains. Crystalline cPLAs with Mn around 9 000 and 14 000 were annealed at 140 °C in the presence of ScOct2 or dibutyl-2-stanna-1,3-dithiolane (DSTL). Simultaneously, crystallites of extended linear chains and crystallites of extended cycles were formed regardless of the catalyst, indicating that transesterification reaction proceeded different for linear chains and for cycles, governed by thermodynamic control. The formation of extended chain crystallites with low dispersity indicates the existence of symproportionation of short and long chains. A complementary experiment was carried out with a PLA ethyl ester composed mainly of linear chains with a small fraction of cycles
The DACHS (Database for Automation, Characterization and Holistic Synthesis) project aims to create completely traceable experimental data, covering syntheses, measurements, analyses, and interpretations. DACHS_MOFs focuses on the synthesis and characterisation of metal-organic frameworks, across multiple, automation-assisted experimental series (AutoMOFs), with the overall goal of producing reproducible MOF samples through tracking of the synthesis parameters.
DACHS_MOFs is simultaneously used to test the DACHS principles.
This upload contain synthesis data from AutoMOFs_2 in HDF5 format (.h5). Each .h5 file contains detailed information on the chemical, experimenal, and synthesis parameters used during the synthesis of a single AutoMOF sample.
Nichtelektrischer Explosionsschutz - Grundlagen und Maßnahmen zum nichtelektrischen Explosionsschutz
(2024)
Bei Geräten und Maschinen zur bestimmungsgemäßen Verwendung in explosionsgefährdeten Bereichen gemäß 2014/34/EU muss in der europäischen Union eine Zündgefahrenbewertung durchgeführt werden. Dabei müssen unter anderem die Gefahren von nichtelektrischen Zündquellen betrachtet werden, zu denen auch die mechanischen Schlagvorgänge gehören.
Bei mechanischen Schlagvorgängen kommt es infolge des Zusammenstoßes zweier Werkstücke bzw. Bauteile zu einer Umwandlung der kinetischen Energie. Dabei erhöht sich die Temperatur der Werkstoffe an der Kontaktstelle und es kommt unter Umständen zu einem Abtrennvorgang kleiner Partikel erhöhter Temperatur. Sowohl die heißen Kontaktstellen (Zündquelle "heiße Oberflächen") als auch die abgetrennten Partikel (Zündquelle "mechanisch erzeugte Funken") können eine wirksame Zündquelle für ein explosionsfähiges Gasgemisch darstellen.
Zur Festlegung von Grenzwerten wurden in der Norm DIN EN ISO 80079-36:2016 die Gasgemische anhand ihrer Explosionsgruppe klassifiziert und zu jeder Gruppe die maximale Energie des Schlagvorgangs festgelegt, unter derer die Entstehung einer wirksamen Zündquelle als unwahrscheinlich angenommen werden kann.
Weitere Festlegungen von Grenzwerten für die kinetische Schlagenergie und geeignete Werkstoffpaarungen finden sich u.a. in der DIN EN 1755 (ex-geschützte Flurförderzeuge) und in der DIN EN 14986 (ex-geschützte Ventilatoren).
Soybean oil takes around half of the vegetable oil resources in the world, increasing in importance constantly. Besides, soy oil plants have experienced numerous accidents due to the coexistence of soy flour and hexane (as a solvent) in the extraction process, thus creating a hazardous environment. This study aims to find the maximum pressure, the maximum rate of pressure rise, and the minimum ignition energy of soy flour−hexane mixtures through specific experiments by varying the concentration of fuels in air and ignition mechanism (chemical igniters or exploding wires). The results have shown that soy flour alone is hard to ignite, whereas adding hexane even in small amounts increases the hazard and the severity of the explosions considerably. Eventually, the substitution of hexane with a greener and safer extraction agent should be of utmost focus.
This research was aimed at comparing the fire characteristics of different types of pepper in the context of explosion prevention. The following characteristics were studied: explosion pressure Pmax and Kst at selected concentrations, ignition temperature of the deposited dust layer from the hot surface, and minimum ignition energy. The comparison of the chemical properties of the used types of pepper was performed using TG/DSC. The results of the measurements suggest that different types of peppers exhibit different explosion characteristics. Each sample reached the maximum value of the explosion pressure and rate of pressure rise at different concentrations. The volume of the explosion chamber used also influenced the explosion characteristics. It is a consequence of the fact that the explosion characteristics strongly depend on the mechanism of action of a particular igniter. The minimum effect on the safety characteristics was observed when measuring the minimum ignition energy and the minimum ignition temperature of the dust layer from the hot surface. The results of the measurements suggest that different types of peppers exhibit different explosion characteristics. This information should then be considered in explosion prevention.
Referenzmaterialien sind entscheidend für die Qualitätssicherung von Laboratorien. Diese nutzen Referenzmaterialien unter anderem zur Validierung von Messverfahren und zur Kalibrierung von Geräten. Dabei ist zu beachten, dass zertifizierte Merkmalswerte stets eine gewisse Unsicherheit aufweisen. Die Ermittlung dieser Unsicherheitsbeiträge ist Gegenstand des Artikels. Des Weiteren wird ein Vorgehen beschrieben, wie die Unsicherheit von Messverfahren mit Hilfe eines Referenzmaterials bestimmt werden kann.