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Paper des Monats
- ja (1)
Weltweit werden etwa 80–85 % aller abgebauten Rohphosphate für die Produktion von Düngemitteln verwendet. Bei noch steigendem Bedarf an Phosphor (P) geht man derzeit davon aus, dass die weltweiten P-Reserven noch über 200 Jahre ausreichen. Um den P-Vorrat langfristig abzusichern, sollte der in Reststoffen enthaltene Phosphor möglichst umfänglich genutzt werden. Dieser Forderung trägt das von der Bundesregierung 2012 erstmals beschlossene Deutsche Ressourceneffizienzprogramm ProgRess Rechnung. Rohphosphat wird auch seitens der Europäischen Kommission aufgrundseiner ökonomischen Bedeutung und des unsicheren Angebots als „kritischer Rohstoff“ eingestuft. Vor diesem Hintergrund hat die Bundesregierung in der Verordnung zur Neuordnung der Klärschlammverwertung vom 27. September 2017 in Deutschland eine verpflichtende technische Rückgewinnung von Phosphor für Abwasserbehandlungsanlagen ab einer Ausbaugröße von 100.000 Einwohnerwerten (12 Jahre nach Inkrafttreten der Verordnung) bzw. ab einer Ausbaugröße von über 50.000 Einwohnerwerten (15 Jahre nach Inkrafttreten der Verordnung) vorgeschrieben. Die Verordnung enthält keine Vorgaben hinsichtlich der anzuwendenden Technologie bei der Phosphorrückgewinnung. Ausgenommen von der Rückgewinnungspflicht sind Klärschlämme mit niedrigen Phosphorgehalten (weniger als 20 Gramm Phosphor je Kilogramm Klärschlamm-Trockenmasse). Auch die im Jahre 2017 verabschiedeten neuen Rechtsvorschriften für die Düngung verlangen zukünftig einen nachhaltigen und ressourceneffizienten Umgang mit Nährstoffen bei der landwirtschaftlichen Erzeugung und schränken die P-Zufuhr insbesondere auf hoch versorgten Böden ein (Düngeverordnung vom 26. Mai 2017). Dies wird zu einem mehr am Pflanzenbedarf orientierten und ggf. vermehrt überbetrieblichen Einsatz von wirtschaftseigenen Düngern führen. Um den politischen und gesetzlichen Anforderungen gerecht zu werden, müssen einerseits wirksame und kosteneffiziente technische Verfahren zum P-Recycling (weiter)entwickelt werden. Andererseits müssen die Recyclingprodukte die Anforderungen für eine direkte Verwendung in der Landwirtschaft oder als Rohstoff für die Herstellung von Düngemitteln erfüllen. In dem vorliegenden Standpunkt wird zunächst der potenzielle Beitrag von Reststoffen zur Deckung des P-Bedarfs in der deutschen Pflanzenproduktion geschätzt. Für die wichtigsten Reststoffe werden technische Verfahren zur P-Rückgewinnung bzw. Aufarbeitung skizziert. Auf Basis der Anforderungen der Landwirtschaft bzw. der Düngemittelindustrie
an die P-Recyclingprodukte werden deren Herstellungsverfahren bewertet. Schließlich wird der Regelungs- und Forschungsbedarf formuliert.
The Brazilian sugarcane industry produced around 173 million tons (Mt) of bagasse in 2018. Bagasse is a by-product of juice extraction for ethanol and sugar production and is combusted in order to generate power, producing up to 10 Mt of ash per year. This ash contains various concentrations of plant nutrients, which allow the ash to be used as a crop fertilizer. However, the concentration and extractability of phosphorus (P), an essential plant nutrient, are low in bagasse ash. To increase the P content, we co-gasified and co-combusted bagasse with P-rich chicken manure. The resulting ash was thermochemically post-treated with alkali additives (Na2SO4 and K2SO4) to increase the availability of P to plants. We aimed to: (i) investigate the effect of thermochemical post-treatment of co-gasification residue and co-combustion ash on P availability to soybeans, (ii) explore the potential of chemical extraction methods (citric acid, neutral ammonium citrate, formic acid, and Mehlich-I) and diffusive gradients in thin films (DGT) to predict the availability of P to soybeans, and (iii) identify the responsible P-phases using X-ray diffraction . We evaluated P availability to soybeans growing in Brazilian Oxisol soil in two independent greenhouse pot experiments. The positive effect of thermochemical treatment on P availability from gasification residue was confirmed through the observation of increased P uptake and biomass in soybean plants. These findings were confirmed by chemical extraction methods and DGT. The gasification residue contained whitlockite as its main P-bearing phase. Thermochemical post-treatment converted whitlockite into highly soluble CaNaPO4. In contrast, co-combustion ash already contained highly soluble Ca(Na,K)PO4 as its main P-bearing phase, making thermochemical post-treatment unnecessary for increasing P availability. In conclusion, increased extractability and availability of P for soybeans were closely connected to the formation of calcium alkali phosphate. Our findings indicate that this combined methodology allows for the prediction of P-fertilization effects of ash.
The CCQM-K148.a comparison was coordinated by the BIPM on behalf of the CCQM Organic Analysis Working Group for NMIs and DIs which provide measurement services in organic analysis under the CIPM MRA. It was undertaken as a "Track A" comparison within the OAWG strategic plan. CCQM-K148.a demonstrates capabilities for assigning the mass fraction content of a solid organic compound having moderate molecular complexity, where the compound has a molar mass in the range (75 - 500) g/mol and is non-polar (pKow < −2), when present as the primary organic component in a neat organic solid and where the mass fraction content of the primary component in the material is in excess of 950 mg/g.
Participants were required to report the mass fraction of Bisphenol A present in one supplied unit of the comparison material. Participants using a mass balance method for the assignment were also required to report their assignments of the impurity components present in the material. Methods used by the seventeen participating NMIs or DIs were predominantly based on either stand-alone mass balance (summation of impurities) or qNMR approaches, or the combination of data obtained using both methods. The results obtained using thermal methods based on freezing-point depression methods were also reported by a limited number of participants. There was excellent agreement between assignments obtained using all three approaches to assign the BPA content.
The assignment of the values for the mass fraction content of BPA consistent with the KCRV was achieved by most of the comparison participants with an associated relative standard uncertainty in the assigned value in the range (0.1 - 0.5)%.
An international intercomparison involving eight national metrology institutes (NMIs) was conducted to establish their current measurement capabilities for determining five selected congeners from the brominated flame retardant classes polybrominated diphenyl ethers and polybrominated biphenyls. A candidate reference material consisting of polypropylene fortified with technical mixtures of penta-, octa- and decabromo diphenyl ether and decabromo biphenyl, which was thoroughly assessed for material homogeneity and stability, was used as study material. The analytical procedures applied by the participants differed with regard to sample pre-treatment, extraction, clean-up, employed calibrants and type of calibration procedure as well as regarding analytical methods used for separation, identification and quantification of the flame retardant congeners (gas chromatography coupled to an electron capture detector (GC-ECD), gas chromatography-mass spectrometry in the electron ionisation mode (GC-EI-MS), gas chromatography-mass spectrometry in the electron capture negative ionisation mode (GC-ECNI-MS), and liquid chromatography-inductive coupled plasma-mass spectrometry (LC-ICP-MS)). The laboratory means agreed well with relative standard deviations of the mean of means of 1.9%, 4.8%, 5.5% and 5.4% for brominated diphenyl ether (BDE) 47, 183 and 209 and for the brominated biphenyl (BB) congener 209, respectively. For BDE 206, a relative standard deviation of 28.5% was obtained. For all five congeners, within-laboratory relative standard deviations of six measurements obtained under intermediate precision conditions were between 1% and 10%, and reported expanded measurements uncertainties typically ranged from 4% to 10% (8% to 14% for BDE 206). Furthermore, the results are in good agreement with those obtained in the characterization exercise for determining certified values for the flame retardant congeners in the same material. The results demonstrate the state-of-the-art measurement capabilities of NMIs for quantifying representative BDE congeners and BB 209 in a polymer. The outcome of this intercomparison (pilot study) in conjunction with possible improvements for employing exclusively calibrants with thoroughly assessed purity suggests that a key comparison aiming at underpinning calibration and measurement capability (CMC) claims of NMIs can be conducted.
KEY COMPARISON
Under the auspices of the Organic Analysis Working Group (OAWG) of the Comité Consultatif pour la Quantité de Matière (CCQM) a key comparison, CCQM K55.c, was coordinated by the Bureau International des Poids et Mesures (BIPM) in 2012. Twenty National Measurement Institutes or Designated Institutes and the BIPM participated. Participants were required to assign the mass fraction of valine present as the main component in the comparison sample for CCQM-K55.c. The comparison samples were prepared from analytical grade L-valine purchased from a commercial supplier and used as provided without further treatment or purification.
Valine was selected to be representative of the performance of a laboratory's measurement capability for the purity assignment of organic compounds of low structural complexity [molecular weight range 100300] and high polarity (pKOW > –2).
The KCRV for the valine content of the material was 992.0 mg/g with a combined standard uncertainty of 0.3 mg/g. The key comparison reference value (KCRV) was assigned by combination of KCRVs assigned from participant results for each orthogonal impurity class. The relative expanded uncertainties reported by laboratories having results consistent with the KCRV ranged from 1 mg/g to 6 mg/g when using mass balance based approaches alone, 2 mg/g to 7 mg/g using quantitative 1H NMR (qNMR) based approaches and from 1 mg/g to 2.5 mg/g when a result obtained by a mass balance method was combined with a separate qNMR result.
The material provided several analytical challenges. In addition to the need to identify and quantify various related amino acid impurities including leucine, isoleucine, alanine and a-amino butyrate, care was required to select appropriate conditions for performing Karl Fischer titration assay for water content to avoid bias due to in situ formation of water by self-condensation under the assay conditions. It also proved to be a challenging compound for purity assignment by qNMR techniques.
There was overall excellent agreement between participants in the identification and the quantification of the total and individual related structure impurities, water content, residual solvent and total non-volatile content of the sample. Appropriate technical justifications were developed to rationalise observed discrepancies in the limited cases where methodology differences led to inconsistent results.
The comparison demonstrated that to perform a qNMR purity assignment the selection of appropriate parameters and an understanding of their potential influence on the assigned value is critical for reliable implementation of the method, particularly when one or more of the peaks to be quantified consist of complex multiplet signals.
The acid catalyzed solgel type synthesis of polyorganosiloxane core-shell nanoparticles with removable PDMS core in aqueous dispersion leads to the inherent formation of a bimodal size distribution with smaller spheres having approximately 26 nm radii and larger nanoparticles with 60 nm in radius. The origin of the self-organized bimodality is investigated and finally attributed to a combination of stabilization of the growing particles due to i) a miniemulsion-type stabilization by the ultrahydrophobe PDMS and ii) by surface co-stabilization by the employed surfactant. The significant influence of temperature, pH, stirrer speed and amount of the surfactant on the particle sizes allows for the design and fine-tuning of different nanoparticles sizes and distributions.
Absolute upconversion quantum yields of blue-emitting LiYF4:Yb3+,Tm3+ upconverting nanoparticles
(2018)
The upconversion quantum yield (QY) is an essential parameter for the characterization of the optical performance of lanthanoid-doped upconverting nanoparticles (UCNPs). Despite its nonlinear dependence on excitation power density, it is typically reported only as a single number. Here, we present the first measurement of absolute upconversion quantum yields of the individual emission bands of blue light-emitting LiYF4:Yb3+,Tm3+ UCNPs in toluene. Reporting the quantum yields for the individual emission bands is required for assessing the usability of UCNPs in various applications that require upconverted light of different wavelengths, such as bioimaging, photocatalysis and phototherapy.
Here, the reliability of the QY measurements is demonstrated by studying the same batch of UCNPs in three different research groups. The results show that whereas the total upconversion quantum yield of these UCNPs is quite high - typically 0.02 at a power density of 5 W/cm2 — most of the upconverted photon flux is emitted in the 794 nm upconversion band, while the blue emission band at 480 nm is very weak, with a much lower quantum yield of 6 times 10^5 at 5 W/cm2. Overall, although the total upconversion quantum yield of LiYF4:Yb3+,Tm3+ UCNPs seems satisfying, notably for NIR bioimaging, blue-light demanding phototherapy applications will require better-performing UCNPs with higher blue light
upconversion quantum yields.
The process of ensuring reliability of NDT applications contains various aspects, such as determining the performance and probability of success, the uncertainty in measurement, the provision of clear and functional procedures and ensuring the correct application accordingly. Test specimens have become powerful elements in supporting many of these aspects. Within the committee for NDT in Civil Engineering (NDT-CE) of the German Society for Nondestructive Testing (DGZfP), the subcommittee on Quality Assurance (UA-QS) therefore addresses the design and the integration of test specimens in the quality assurance process. Depending on the specific purpose, the requirements on test specimens can vary significantly based on the defined simulated scenario. The most prominent purposes of test specimens might be seen in providing references for inspection systems in regard to function control, calibration and validation. Further aspects can be parametric studies, basic investigation of physical principles related to NDT or a simplified and therefore comprehensive demonstration of inspection concepts (e.g. for teaching purposes). The specific purpose of a test specimen dictates the requirements regarding its conception, including the exact design, the material or the fabrication accuracy and the conditioning. In the development of a general guideline by the UA-QS for application-specific procedures and their validation, the use of test specimens is addressed and specific concepts for the design of test specimens are made. This includes the analysis of the measurement process regarding any given application, deriving an adequate calibration approach for it and designing test specimens (calibration specimens) accordingly. Furthermore, it includes the validation of the procedure taking into account all conditions related to the specific application in the field. The validation requires a statistically sufficient number of trials. Thorough evaluation of each trial can only be established if the ground-truth is known. Therefore, test specimens providing a realistic but controlled simulation of the inspection problem are valuable and indispensable elements in the validation process. The requirement of being fully realistic will often not be possible to fulfill due to practical restrictions. Any aspect that cannot be included in the simulation realistically needs to be simulated conservatively. This again, requires a sufficient understanding of the inspection principle and technique to ensure conservativeness. Among other quality-assurance-related aspects, the UA-QS establishes concepts and guidelines regarding sound and efficient approaches for the specific purposes of test specimens. This subcommittee brings together representatives of different Groups along the entire value chain of NDT-CE, including researchers, practitioners, manufacturers and clients. They all work together in establishing a common understanding and level of quality assurance in the industry.
Stahlbetontragwerke sind eine wichtige Konstruktionsweise im Bauwesen und ein wachsendes Anwendungsfeld für die Zerstörungsfreie Prüfung (ZfP).
Zur Sicherung der Tragsicherheit, strukturellen Integrität, Bestimmung von Geometrien und zur Detektion konstruktiver Elemente wie z.B. Bewehrung, Verankerungen und Spannkanälen besitzen zerstörungsfreie Prüfverfahren in diesem Bereich inzwischen große Relevanz. Durch den bislang erreichten Fortschritt in der Forschung und Entwicklung haben moderne akustische und elektromagnetische Verfahren eine beachtliche Leistungsfähigkeit erreicht. Von Geräteherstellern sind diese in kommerziellen Produktserien umgesetzt worden und finden eine zunehmend breite Anwendung in der Praxis. In einigen anderen Anwendungsgebieten, in denen die ZfP bereits fester Bestandteil von Überwachungen ist, wie z.B. im Maschinenbau und insbesondere in der Kerntechnik und der Luftfahrt, existieren umfangreiche Qualitätssicherungssysteme für die konforme Anwendung und zuverlässige Einbeziehung der ZfP. Dem relativ jungen Entwicklungsstadium moderner ZfP für Stahlbetonbauteile entsprechend müssen solche Konzepte im Bauwesen erst noch entwickelt bzw. implementiert werden.
Dementsprechend hat sich der Unterausschuss Qualitätssicherung (UA- S) des Fachausschusses ZfP im Bauwesen (ZfPBau) die Definition und Verbesserung der Qualität von ZfP-Anwendungen sowie insbesondere die verfahrensunabhängige Standardisierung von Prüfprozeduren und statistische Absicherung der Prüfergebnisse zum Ziel gemacht.
Die aktuellen Arbeitsfelder beinhalten die Entwicklung praxisgerechter Konzepte für Prüfprozeduren und deren Erprobung in einem Ringversuch sowie die Konzeption von Testkörpern hinsichtlich unterschiedlicher Aspekte wie Parameterstudien, Validierung, Kalibrierung und Simulation. Dabei werden Ansätze anderer Branchen durchaus einbezogen, die Anpassung an die spezifischen Bedürfnisse und Gegebenheiten des Bauwesens wird jedoch als wesentlich angesehen und stellt somit eine wichtige Vorgabe dar.
Da die Tätigkeiten nicht auf einzelne Verfahren begrenzt sind, müssen generelle Vorgehensweisen entwickelt werden, die sich auf die jeweiligen Verfahren konkretisieren lassen. Der Vortrag gibt hierzu erste Einblicke in die Arbeit des Ausschusses.
The field of non-destructive testing of civil structures (NDT-CE) has been continuously growing. Due to the complexity and diversity of civil constructions as well as the heterogeneity of concrete, specific standards or guidelines for the application of modern NDT-CE are still missing. The development of individual solutions is the current approach, which is just as challenging as it is common for NDT-CE.
With the increasing development and commercialization of NDT-CE technology, the group of practitioners is growing. To ensure a good level of quality in the industry, it appears necessary to establish adequate means.
Naturally, the performance of NDT-CE methods regarding a specific application is strongly dependent on choosing the most suitable inspection technique and applying it correctly, generally referred to as the inspection procedure in the field of NDT. There are well-defined guidelines regarding procedure documentation and handling in many fields of NDT (e.g. nuclear, aerospace or automotive) according to the high importance of procedures in assuring a successful and reliable application. For a long time, this has not always been the case with NDT-CE, which is still considered a unique discipline of NDT. Part of the reason for that might be the young development state of NDTCE, the heterogeneity of building materials like concrete, timber or masonry as a material and the diversity of civil structures. In consequence, NDT-CE procedure development is considered challenging.
Among other aspects, addressed in the subcommittee on Quality Assurance (UA-QS) within the committee for NDT-CE of the German Society for Nondestructive Testing (DGZfP), part of its work aims at establishing an adequate basis for NDT-CE procedure development. While some of the highly developed approaches from other industries are taken into consideration, they need to be analyzed regarding their suitability for NDT-CE and adapted accordingly. For a procedure to be as defined as possible, it needs to contain sufficient information, such as the scope and limitations regarding material, geometry and condition of the test object, inspection parameters, calibration, data acquisition, analysis criteria as well as requirements regarding the inspection personnel.
For a successful implementation in the field, it is important to define the specific procedure as precisely as possible. Despite the necessity of a great amount of information to be included, the procedure needs to be suitable for efficient field application.
The UA-QS is developing a guideline for NDT-CE procedures suitable for application in this field of NDT to ensure correct and reproducible application. To demonstrate and evaluate this concept, specific examples of procedures are also produced. In particular, the UA-QS has developed a procedure for the detection and positioning of tendon ducts using Ground Penetrating Radar (GPR). This procedure is tested regarding the practical applicability in a roundrobin on a defined type of reference test block.
Die agronomische Effizienz von Düngemitteln wird üblicherweise im Vegetationsversuch geprüft. Vegetationsversuche erlauben die Betrachtung unterschiedlicher Kulturpflanzen und deren Strategien der Nährstoffmobilisierung und -Aneignung ebenso wie die Berücksichtigung verschiedener Substrattypen und deren Eigenschaften hinsichtlich Nährstofffixierung und -freisetzung. Solche Versuche, selbst wenn sie nicht im Feld, sondern nur im Gefäß durchgeführt werden, sind jedoch sowohl zeit- als auch kostenintensiv. In erster Näherung wird die Pflanzenverfügbarkeit insbesondere von Phosphor (P)-Düngemitteln daher herkömmlicherweise mit Hilfe standardisierter chemischer Extraktionsmethoden abgeschätzt, deren Durchführung in der deutschen ebenso wie in der europäischen Düngemittelverordnung normiert ist. Diese Methoden werden auch im Rahmen der staatlichen Düngemittelverkehrskontrolle genutzt, um die Einhaltung düngemittelrechtlicher Vorgaben zu überprüfen. Wie jüngere Arbeiten gezeigt haben, ist jedoch die Übertragung herkömmlicher Standardextraktionsmethoden auf neue Dünger aus Recyclingmaterialien wie Klärschlamm mit einigen Schwierigkeiten verbunden. Korrelationen zwischen P-Aufnahme im Vegetationsversuch und chemischer Löslichkeit im Standardextrakt sind oft nur mäßig bis schwach oder überhaupt nicht signifikant. Die vorliegende Literaturübersicht gibt einen Überblick zum aktuellen Stand des Wissens über die chemische Löslichkeit von klärschlammbasierten P-Recyclingdüngern, deren Effizienz im Vegetationsversuch und statistische Relationen zwischen beiden Parametern. Anschließend werden alternative Methoden
zur Abschätzung der P-Verfügbarkeit von Recyclingdüngern vorgestellt, die derzeit Gegenstand der wissenschaftlichen Diskussion sind.
Phosphorus (P) is an essential element for all life forms, and P-availability thus an important driver of a functioning agriculture. However, phosphate rock resources for P-fertilizer production are only available in a few countries. Therefore, P-recovery from waste materials has become of increasing interest during the last decade and has been investigated worldwide. In order to characterize potential novel P-fertilizers made from recycled materials, a large array of P-compound characterizations, chemical extractions and growth experiments were performed. This review bundles the work carried out in that field over the last years. Overall, P-fertilizers from recycled materials show a broad range of P-compounds with very different chemical structure and solubility. Growth experiments performed to assess their fertilizing effects display high variations for most of the products. While these experiments have demonstrated that some fertilizers made of recycled materials may reach P effects in the same order of magnitude as water-soluble phosphate rock-based fertilizers, an important limitation in their interpretation is the fact that they often vary considerably in their experimental design. The existing data show clearly that standardization of growth experiments is urgently needed to achieve comparable results. Standard chemical extractants used to assess the chemical solubility of P-fertilizers were found to be of limited reliability for predicting plant P uptake. Therefore, alternative methods such as sequential fractionation, or the extraction of incubated soil/fertilizer mixtures with standard soil extractants or with P sink methods should be tested more intensively in the future to provide alternative options to predict the P-availability of fertilizers from recycled materials.
Die agronomische Effizienz von Düngemitteln wird üblicherweise in Vegetationsversuchen geprüft. Diese erlauben die es, unterschiedliche Kulturpflanzen und deren Strategien der Nährstoffmobilisierung und -aneignung zu betrachten und verschiedene Substrattypen und deren Eigenschaften im Hinblick auf Nährstofffixierung und -freisetzung zu berücksichtigen. Solche Versuche, selbst wenn sie nicht im Feld, sondern nur im Gefäß durchgeführt werden, sind jedoch sowohl zeit- als auch kostenintensiv. In erster Näherung wird die Pflanzenverfügbarkeit insbesondere von Phosphor (P)-Düngemitteln daher in der Regel mit Hilfe standardisierter chemischer Extraktionsmethoden abgeschätzt, deren Durchführung in der deutschen ebenso wie in der europäischen Düngemittelverordnung normiert ist. Diese Methoden werden auch bei der staatlichen Düngemittelverkehrskontrolle genutzt, um zu überprüfen, ob die düngemittelrechtlichen Vorgaben eingehalten werden. Wie jüngere Arbeiten gezeigt haben, ist es jedoch schwierig, herkömmliche Standardextraktionsmethoden auf neue Dünger aus Recyclingmaterialien wie Klärschlamm zu übertragen. Korrelationen zwischen P-Aufnahme im Vegetationsversuch und chemischer Löslichkeit im Standardextrakt sind oft nur mäßig bis schwach oder überhaupt nicht signifikant. Die vorliegende Literaturübersicht gibt einen Überblick zum aktuellen Stand des Wissens über die chemische Löslichkeit von klärschlammbasierten P-Recyclingdüngern, deren Effizienz im Vegetationsversuch und statistische Relationen zwischen beiden Parametern. Anschließend werden alternative Methoden zur Abschätzung der P-Verfügbarkeit von Recyclingdüngern vorgestellt, die derzeit Gegenstand der wissenschaftlichen Diskussion sind.
The nucleophilic substitution of fluorine of aromatic compounds with n-aminoalkyl trialkoxysilanes and consecutive sol-gel process have been used for the fabrication of various chromophoric sol-gel materials. The displacement of the fluoro substituent of an activated aromatic molecule occurs by a primary or secondary amino group of (CH3O)3Si-(CH2)3-NHR [R- = H-; CH3-, (CH3O)3Si-(CH2)3-] in tetraalkoxysilane or alcohol as solvent and the sol-gel process can be carried in the same vessel. The HF formed is trapped by a tertiary amine and simultaneously serves as the catalyst for the sol-gel process. Various aromatic compounds have been checked for this purpose: 1-(4-fluorophenyl)-2-nitroethylene, 1-(4-fluorophenyl)-2,2-dicyanoethylene, 4-fluorobenzonitrile, 4-fluoronitrobenzene, 4,4prime-difluorobenzophenone, 4,4prime-difluorobenzil, 7,7prime-difluorodibenzylideneacetone, tetrafluoro-p-benzoquinone, and 1,5-difluoro-2,4-dinitrobenzene. Mono and disubstitution has been studied by UV/Vis- and solid state NMR spectroscopy of the xerogels.
We report on a new series of isoreticular frameworks based on zinc and 2-substituted imidazolate-4-amide-5-imidate (IFP-1–4, IFP=imidazolate framework Potsdam) that form one-dimensional, microporous hexagonal channels. Varying R in the 2-substitued linker (R=Me (IFP-1), Cl (IFP-2), Br (IFP-3), Et (IFP-4)) allowed the channel diameter (4.0–1.7 Å), the polarisability and functionality of the channel walls to be tuned. Frameworks IFP-2, IFP-3 and IFP-4 are isostructural to previously reported IFP-1. The structures of IFP-2 and IFP-3 were solved by X-ray crystallographic analyses. The structure of IFP-4 was determined by a combination of PXRD and structure modelling and was confirmed by IR spectroscopy and 1H MAS and 13C CP-MAS NMR spectroscopy. All IFPs showed high thermal stability (345–400°C); IFP-1 and IFP-4 were stable in boiling water for 7 d. A detailed porosity analysis was performed on the basis of adsorption measurements by using various gases. The potential of the materials to undergo specific interactions with CO2 was investigated by measuring the isosteric heats of adsorption. The capacity to adsorb CH4 (at 298 K), CO2 (at 298 K) and H2 (at 77 K) at high pressure were also investigated. In situ IR spectroscopy showed that CO2 is physisorbed on IFP-1–4 under dry conditions and that both CO2 and H2O are physisorbed on IFP-1 under moist conditions.
Short diffusion paths and high specific interfacial areas in microstructured devices can increase mass transfer rates and thus accelerate multiphase reactions. This effect can be intensified by the application of ultrasound. Herein, we report on the design and testing of a novel versatile setup for a continuous ultrasound-supported multiphase process in microstructured devices on a preparative scale. The ultrasonic energy is introduced indirectly into the microstructured device through pressurized water as transfer medium. First, we monitored the influence of ultrasound on the slug flow of a liquid/liquid two-phase system in a channel with a high-speed camera. To quantify the influence of ultrasound, the hydrolysis of p-nitrophenyl acetate was utilized as a model reaction. Microstructured devices with varying channel diameter, shape, and material were applied with and without ultrasonication at flow rates in the mL min-1 range. The continuous procedures were then compared and evaluated by performing a simplified life cycle assessment.
Synthesis of new upconversion (UC) materials that can convert near-infrared excitation light into visible emission light with high efficiency has crucial importance for energy and bio-applications. Herein, SrF2 single crystals with a doping concentration of 2 mol% Er3+ and 2–8 mol% Yb3+ were synthesized and the optical properties were studied. The absorption cross-section of the different doping ions was calculated. To identify the most efficient and brightest material absolute excitation power dependent UC photoluminescence quantum yields (ϕUC) and brightness values were determined. In addition, excitation characteristics and luminescence lifetimes were analysed to understand the changes in population pathways and possible quenching mechanisms. A dominant two-photon population behaviour of the red and green emission bands was observed for all investigated doping concentrations of Yb3+ and Er3+. The ϕUC value of 6.5% measured using 230 W cm−2 of 976 nm excitation for SrF2 crystal co-doped with 2 mol% Er3+ and 3 mol% Yb3+. These findings broaden the scope of efficient UC materials apart from the record UC material β-NaYF4:Yb3+, Er3+ and provide benchmark values for cubic-phase and especially SrF2- nano and micrometer sized materials.
Characterization of polymer nanoparticles by asymmetrical flow field flow fractionation (AF-FFF)
(2010)
Bright emitters with photoluminescence in the spectral region of 800–1600 nm are increasingly important as optical reporters for molecular imaging, sensing, and telecommunication and as active components in electrooptical and photovoltaic devices. Their rational design is directly linked to suitable methods for the characterization of their signal-relevant properties, especially their photoluminescence quantum yield (Φf). Aiming at the development of bright semiconductor nanocrystals with emission >1000 nm, we designed a new NIR/IR integrating sphere setup for the wavelength region of 600–1600 nm. We assessed the performance of this setup by acquiring the corrected emission spectra and Φf of the organic dyes Itrybe, IR140, and IR26 and several infrared (IR)-emissive Cd1-xHgxTe and PbS semiconductor nanocrystals and comparing them to data obtained with two independently calibrated fluorescence instruments absolutely or relative to previously evaluated reference dyes. Our results highlight special challenges of photoluminescence studies in the IR ranging from solvent absorption to the lack of spectral and intensity standards together with quantum dot-specific challenges like photobrightening and photodarkening and the size-dependent air stability and photostability of differently sized oleate-capped PbS colloids. These effects can be representative of lead chalcogenides. Moreover, we redetermined the Φf of IR26, the most frequently used IR reference dye, to 1.1 × 10-3 in 1,2-dichloroethane DCE with a thorough sample reabsorption and solvent absorption correction. Our results indicate the need for a critical reevaluation of Φf values of IR-emissive nanomaterials and offer guidelines for improved Φf measurements.
Sugarcane bagasse is commonly combusted to generate energy. Unfortunately, recycling strategies rarely consider the resulting ash as a potential fertilizer. To evaluate this recycling strategy for a sustainable circular economy, we characterized bagasse ash as a fertilizer and measured the effects of co-gasification and co-combustion of bagasse with either chicken manure or sewage sludge: on the phosphorus (P) mass fraction, P-extractability, and mineral P phases. Furthermore, we investigated the ashes as fertilizer for soybeans under greenhouse conditions. All methods in combination are reliable indicators helping to assess and predict P availability from ashes to soybeans. The fertilizer efficiency of pure bagasse ash increased with the ash amount supplied to the substrate. Nevertheless, it was not as effective as fertilization with triple-superphosphate and K<sub>2</sub>SO<sub>4</sub>, which we attributed to lower P availability. Co-gasification and co-combustion increased the P mass fraction in all bagasse-based ashes, but its extractability and availability to soybeans increased only when co-processed with chicken manure, because it enabled the formation of readily available Ca-alkali phosphates. Therefore, we recommend co-combusting biomass with alkali-rich residues to increase the availability of P from the ash to plants.
Although catalytic reductions, cross-couplings, metathesis, and oxidation of C=C double bonds are well established, the corresponding catalytic hydroxylations of C–H bonds in alkanes, arenes, or benzylic (allylic) positions, particularly with O2, the cheapest, 'greenest', and most abundant oxidant, are severely lacking. Certainly, some promising examples in homogenous and heterogenous catalysis exist, as well as enzymes that can perform catalytic aerobic oxidations on various substrates, but these have never achieved an industrial-scale, owing to a low space-time-yield and poor stability. This review illustrates recent advances in aerobic oxidation catalysis by discussing selected examples, and aims to stimulate further exciting work in this area. Theoretical work on catalyst precursors, resting states, and elementary steps, as well as model reactions complemented by spectroscopic studies provide detailed insight into the molecular mechanisms of oxidation catalyses and pave the way for preparative applications. However, O2 also poses a safety hazard, especially when used for large scale reactions, therefore sophisticated methodologies have been developed to minimize these risks and to allow convenient transfer onto industrial scale.
The amount of heat, which is released by fire loads during the combustion
process, depends on the material characteristics, the ventilation
conditions, the storage density and the distribution. To evaluate the
structural stability of buildings in case of fire, the fire load has to be
quantified. In Germany, the fire load is quantified by using the combustion
factor m, while internationally the combustion efficiency χ is
applied. Both factors assess the burning behavior of materials, but the
determination is carried out in different ways. Since the testing facility
was abolished fifteen years ago, it is not possible to determine the combustion
factor m anymore. So, it should be found out, if the combustion
efficiency χ is a convenient method to quantify the fire load under the
consideration of the German standards. As a part of the research, combustion
efficiencies χ were determined for eight materials in the cone
calorimeter and the single burning item test at different heat fluxes.
The values of the combustion efficiencies χ as well as the corresponding
combustion factors m were discussed and compared to the values of the
literature. The results show an influence of the testing facility on the
combustion efficiency. The values of the combustion efficiency determined
in the single burning item test were higher than the values from
the cone calorimeter.
Vor dem Hintergrund der Zurückziehung der DIN 18230 Teil 2 zur Bestimmung des m-Faktors von Materialien für die Brandlastbewertung im Industriebau müssen neue Wege gefunden werden, wie das Abbrandverhalten alternativ quantifiziert werden kann. Der Beitrag fasst die Entstehung und die Entwicklung der Bestimmungsweise von Abbrandfaktoren zusammen und gibt Ausblick auf eine neue Möglichkeit zur Bewertung von Brandlasten, die Verbrennungseffizienz.
NMR und Biomaterialien - Was kann man über plasmagespritzte Apatitschichten und Cellulose lernen?
(2002)
Two different radical polymerization techniques have been applied to covalently graft vinylformamide (VFA) onto silica particles. Grafting by the polymerization of VFA using an immobilized azo initiator on silica has been found less effective, because monomer conversion is limited in non-aqueous solvents and grafting yields are low in water. Radical copolymerization of VFA with vinyltriethoxysilane (VTS)-functionalized silica particles is suitable to produce poly(vinylformamide) (PVFA) silica hybrid particles in respectable yield. The VFA/VTS-silica ratio determines the degree of grafting. The PVFA-VTS-co-grafted silica particles can be acidically hydrolyzed into poly(vinylamine)-grafted silica particles. Molecular structures of the surface groups and grafted polymer chains have been confirmed by means of solid state 13C{1H} cross-polarization magic-angle spinning (CP MAS) NMR spectroscopy. Zeta potential measurements show the altering of the former silica particles surface charges arising from the introduction of basic groups on the surface.
Hydrogen-bearing species in the bone mineral environment were investigated using solid-state NMR spectroscopy of powdered bone, deproteinated bone, and B-type carbonated apatite. Using magic-angle spinning and cross-polarization techniques three types of structurally-bound water were observed in these materials. Two of these water types occupy vacancies within the apatitic mineral crystal in synthetic carbonated apatite and deproteinated bone and serve to stabilize these defect-containing crystals. The third water was observed at the mineral surface in unmodified bone but not in deproteinated bone, suggesting a role for this water in mediating mineral-organic matrix interactions. Direct evidence of monohydrogen phosphate in a 1H NMR spectrum of unmodified bone is presented for the first time. We obtained clear evidence for the presence of hydroxide ion in deproteinated bone by 1H MAS NMR. A 1H-31P heteronuclear correlation experiment provided unambiguous evidence for hydroxide ion in unmodified bone as well. Hydroxide ion in both unmodified and deproteinated bone mineral was found to participate in hydrogen bonding with neighboring water molecules and ions. In unmodified bone mineral hydroxide ion was found, through a 1H-31P heteronuclear correlation experiment, to be confined to a small portion of the mineral crystal, probably the internal portion.
The chemical shift anisotropies (CSAs) of cellulose I and I, the two crystalline constituents of bacterial cellulose produced by Acetobacter xylinum (DSM 14666), and regenerated cellulose II are reported for each of the spectroscopically resolved carbon resonances using the phase adjusted spinning sideband (PASS) experiment. The data are compared with experimental results using the recoupling of anisotropy information (RAI) technique and with theoretical calculations of the structure of cellulose, including the hydrogen bonding systems.
Here, we present a detailed characterisation of rhodamine B-containing magnetoliposomes (FLU-ML), emphasising the dependence of their fluorescence properties on the presence of iron oxide cores, and the molar fraction of the fluorophore. The magnetoliposome types used exist as colloidally stable, negatively charged clusters with an average hydrodynamic diameter of 95 nm. The molar rhodamine B fractions were 0.67 % and 1.97 %. Rhodamine B normalised fluorescence, quantum yields and fluorescence lifetimes were substantially reduced by inner filter effects as the magnetoliposome concentration is increased, by increasing molar rhodamine B fraction, and by quenching originating from the iron oxide cores. MR relaxometry at 3 T revealed extremely high r2 relaxivities (440 to 554 s-1mM-1) and moderately high r1 values (2.06 to 3.59 s-1mM-1). Upon incubating human prostate carcinoma (PC-3) cells with FLU-ML, a dose-dependent particle internalisation was found by MR relaxometry. In addition, the internalised FLU-ML were clearly visible by fluorescence microscopy. At the FLU-ML concentrations used (up to 3 × 103 M Fe) cell viability was not substantially impaired. These results provide valuable insights on the fluorescence properties of bimodal magnetoliposomes and open promising perspectives for the use of these materials as a platform technology for advanced functional and molecular MR and optical imaging applications.
This study proposes a new guideline for designing biodegradable apatite ceramics. Boron-containing hydroxyapatite (BHAp) particles were prepared by a high-temperature solid-state reaction processing method and were characterized in terms of their chemical composition, apatite lattice defects and in vitro biodegradability. Solid-state nuclear magnetic resonance analysis showed that boron-incorporation into hydroxyapatite (HAp) derived by thermo-chemical reactions between borate and calcium phosphate phases led to disordered phases (BCaP) of a CaO–P2O5–B2O3–OH system covering the crystalline HAp core. X-ray diffraction analysis indicated that the BCaP phase must consist mainly of a crystalline oxyboroapatite (OBAp) phase. An in vitro biodegradability test showed that BHAp degraded quicker than HAp or ß-tricalcium phosphate. The biodegradability of BHAp particles can be controlled by boron incorporation into a HAp lattice leading to the formation of a disordered OBAp phase.
The paper gives an overview on safe life and damage tolerance methods applied to railway axles. It describes failure scenarios due to fatigue crack initiation and propagation. Besides common aspects of design, specific features such as corrosion and impact damage from flying ballast are discussed which may reduce the fatigue strength of axles during service. Potential effects of non-metallic inclusions from the steel manufacturing process are addressed in the context of the very high number of loading cycles railway axles are designed for. With respect to damage tolerance general lines of fracture mechanics residual lifetime analyses are introduced. More specific discussion is provided on aspects such as the threshold value of fatigue crack propagation and reliability aspects of non-destructive inspection.
Phosphor ist ein für alle Lebewesen essenzielles Element und kann in seinen Funktionen z. B. als Bestandteil der DNS und RNS sowie als Schlüsselelement beim Energiestoffwechsel (ADP/ATP) nicht ersetzt werden. Klärschlammaschen sind aufgrund ihrer hohen Gehalte an Phosphor (1525 % P2O5) geeignete Sekundärrohstoffe für die Herstellung von P-Düngemitteln. Aufgrund der schlechten Pflanzenverfügbarkeit des Phosphors und der Gehalte an umweltrelevanten Schwermetallen sollten diese allerdings nicht direkt in der Landwirtschaft eingesetzt werden. Im Mittelpunkt des EU-Projekts SUSAN steht die Entwicklung und Optimierung einer thermochemischen Behandlung von Klärschlammaschen, mit der die Düngewirkung der Aschen auf das Niveau konventioneller Mineraldünger (Thomaskali und Superphosphat SSP) angehoben wird und die Schwermetallkonzentrationen unter die Grenzwerte nach Düngemittelverordnungen europäischer Länder abgesenkt werden. Die sehr positiven Ergebnisse, die bisher im SUSAN-Projekt erzielt wurden, und die darauf basierenden ökonomischen Betrachtungen legen eine großtechnische Umsetzung des Verfahrens nahe.
Boron-containing hydroxyapatite (BHAp) particles were synthesized by the wet chemical
processing method and subsequent thermal treatment at the temperature ranging from 700-1200°C,
and examined the effect of boron introduction on the microstructure of BHAp. The local structure
around boron and phosphorus in the BHAp was analyzed by solid-state magic-angle spinning (MAS)
nuclear magnetic resonance (NMR) spectroscopy. The heat-treatment above 700°C induced the
thermal decomposition of HAp to β-TCP and then the chemical reaction between HAp and B(OH)3
was induced above 900°C, resulting in the formation of boron-substituted HAp particles
accompanied by the formation of β-TCP and its transformation to α-TCP above 1200°C.
Ultrasound sensors should be embedded into concrete for monitoring concrete properties. These new longitudinal wave sensors with a center frequency of 60 kHz were examined regarding their suitability for ultrasonic measurements in concrete structures in terms of emission characteristics, sensitivity and frequency ränge.
For the measurement of the radiation patterns, the sensors were embedded vertically and horizontally in concrete cylinders. The directivity pattern was measured using a laser vibrometer.
The sensitivity of the sensor was determined in water using different sensors of the same type. It shows changes in the signal amplitude as well as variations in the frequency ränge for different transmitter-receiver combinations.
The attenuation of the concrete affects the achievable resolution of the measurements and thus, the maximum possible spacing of the sensors within a concrete element. Experimental tests helped optimizing the distances with respect to the required resolution and the effort of embedding the sensors. The signal attenuation in the concrete was measured in the frequency ränge of 60 kHz in response to various degrees of reinforcement and grain size. For this purpose, the sensors were cast at different distances in the specimens studied. The recorded Signals were evaluated for their amplitude and frequency spectrum.
Nuclear magnetic resonance (NMR) has been used for a detailed investigation of the borate incorporation in apatitic biomaterials prepared by high-temperature solid-state reaction sintering. The NMR data clearly show that crystalline hydroxyapatite (HAp) does exist, but it contains only about 30% of the entire phosphate content of the sample. The main phosphate content of about 70% forms a disordered calcium phosphate phase (BCaP) that accommodates the borate units in two structurally different trigonal BO33- groups besides some minor linear BO2- units. The average chemical composition of BCaP was estimated from the NMR spectra. Furthermore, a structural model of these particles is proposed, where HAp forms the crystalline core of these crystals covered by the disordered BCaP, suggesting that the BCaP phase is responsible for the adhesion properties of organic molecules like proteins and not HAp that is the only significant crystalline phase (XRD). Furthermore, the presence of an interface between HAp and BCaP is discussed based on various NMR experiments, including a triple-resonant 11B-31P cross-polarization edited 31P NMR spectrum with subsequent 31P{1H} REDOR (Rotational Echo DOuble Resonance) dephasing.
Here, we present the synthesis, characterization and magnetic separation of magnetic polyorganosiloxane nanoparticles. Magnetic iron oxide nanoparticles with average particle radii of 3.2 nm had been synthesized by a simple coprecipitation process of iron(II) and iron(III) salt in basic solution. Afterwards, the particles were successfully incorporated into a polyorganosiloxane network via a polycondensation reaction of trimethoxymethylsilane (T), diethoxydimethylsilane (D) and the functional monomer (chloromethylphenyl)trimethoxysilane (ClBz-T) in aqueous dispersion. A core–shell system was chosen to increase the flexibility of the system concerning size, composition and functionalization possibilities. The magnetic nanocapsules with particle radii below 60 nm were separated from non-magnetic material with a high effectiveness by the use of commercially available separation columns which are commonly used for isolation of microbeads and subsequently characterized via transmission electron microscopy (TEM), asymmetrical flow field-flow fractionation (AF-FFF), superconducting quantum interference device (SQUID) and Mössbauer spectroscopy.
Nanocrystalline hydroxyapatite (HAp) and silicon-containing hydroxyapatite (SiHAp) particles were synthesized by a wet-chemical procedure and their heterogeneous structures involving a disordered phase were analyzed in detail by X-ray diffractometry (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy and solid-state magic-angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy. The effects of heterogeneous structure on in vitro biodegradability and the biologically active Ca(II)- and Si(IV)-releasing property of SiHAp particles were discussed. The 29Si NMR analysis revealed that the Si(IV) was incorporated in the HAp lattice in the form of Q0 (SiO4-4 or HSiO3-4) species, accompanied by the formation of condensed silicate units outside the HAp lattice structure, where the fraction and amount of Q0 species in the HAp lattice depends on the Si content. The 31P and 1H NMR results agreed well with the XRD, TEM and FTIR results. NMR quantitative analysis results were explained by using a core–shell model assuming a simplified hexagonal shape of HAp covered with a disordered layer, where Si(IV) in Q0 was incorporated in the HAp lattice and a disordered phase consisted of hydrated calcium phosphates involving polymeric silicate species and carbonate anions. With the increase in the Si content in the HAp lattice, the in vitro degradation rate of the SiHAps increased, while their crystallite size stayed nearly unchanged. The biologically active Ca(II)- and Si(IV)-releasing ability of the SiHAps was remarkably enhanced at the initial stage of reactions by an increase in the amount of Si(IV) incorporated in the HAp lattice but also by an increase of the amount of polymeric silicate species incorporated in the disordered phase.
Der Bericht zum Arbeitspaket 3 baut auf den Ergebnissen der internationalen Recherche (AP1) sowie der Zusammenstellung der Randbedingungen und Beanspruchungsgrößen für die Endlagerbehälter (AP2) auf. Die Anforderungen an die Behälter – regulatorische, betriebliche sowie solche aus der Standortgeologie und den Einwirkungen und Prozessen, denen die Behälter ausgesetzt sind – werden hergeleitet und systematisch dargestellt.
Die für das Endlagersystem zu betrachtenden Nutzungsphasen werden aus den regulatorischen Anforderungen hergeleitet und charakterisiert. Die Einwirkungen auf die Behälter in den drei potenziellen Wirtsgesteinen sowie die sich für die Erfüllung der Sicherheitsfunktionen des Behälters als Teil des Endlagersystems ergebenden Behälterfunktionen werden ebenfalls wirtsgesteins- und zeitphasenabhängig betrachtet. Schließlich werden aus den Einwirkungen auf die Behälter und den Anforderungen an die Behälterfunktionen auch quantifizierbare Behälterfunktionen für alle drei potenziellen Wirtsgesteine abgeleitet.
Muon Tomography of the Interior of a Reinforced Concrete Block: First Experimental Proof of Concept
(2021)
Quality assurance and condition assessment of concrete structures is an important topic world-wide due to the aging infrastructure and increasing traffic demands. Common topics include, but are not limited to, localisation of rebar or tendon ducts, geometrical irregularities, cracks, voids, honeycombing or other flaws. Non-destructive techniques such as ultrasound or radar have found regular, successful practical application but sometimes suffer from limited resolution and accuracy, imaging artefacts or restrictions in detecting certain features. Until the 1980s X-ray transmission was used in case of special demands and showed a much better resolution than other NDT techniques. However, due to safety concerns and cost issues, this method is almost never used anymore. Muon tomography has received much attention recently. Novel detectors for cosmic muons and tomographic imaging algorithms have opened up new fields of application, such as the investigation of freight containers. Muon imaging also has the potential to fill some of the gaps currently existing in concrete NDT. As a first step towards practical use and as a proof of concept we used an existing system to image the interior of a reference reinforced 600 kg concrete block. Even with a yet not optimized setup for this kind of investigation, the muon imaging results are at least of similar quality compared to ultrasonic and radar imaging, potentially even better. The data acquisition takes more time and signals contain more noise, but the images allowed to detect the same important features that are visible in conventional high energy X-ray tomography. In our experiment, we have shown that muon imaging has potential for concrete inspection. The next steps include the development of mobile detectors and optimising acquisition and imaging parameters.
Decades of non-destructive evaluation (NDE) for the quality assurance of concrete bridges revealed the necessity of developing procedures for building reference specimens for different defects. External objects have been widely used in specimen construction to represent defects. However, embedded materials can alter the actual defect characteristics, interrupting the NDE responses. This study proposes new approaches to fabricating reference specimens for reinforced concrete that feature substantial defects, including cracks, delamination, honeycombing and rebar corrosion, without external objects. As a result, realistic responses can be acquired to identify promising NDE methods for characterising actual deteriorations. The procedures were produced with the intent of being reproducible in any laboratory. Destructive and non-destructive testing methods were performed to verify the effectiveness of the processes in creating defects. This study provides research laboratories with techniques for
fabricating reference specimens for characterising defects and assessing the performance of NDE technologies.
Bei der Auswahl eines Standortes für ein Endlager für hochradioaktive Abfälle (Wärme entwickelnde radioaktive Abfälle und ausgediente Brennelemente) in Deutschland werden auf Grundlage des Standortauswahlgesetzes von 2017 die drei potenziellen Wirtsgesteine Steinsalz, Tonstein und Kristallingestein in Betracht gezogen. Die Auswahl eines konkreten Endlagerstandortes steht dabei in engem Zusammenhang mit den für die jeweiligen Wirtsgesteine geeignet erscheinender Endlagersystemen. Zentraler Bestandteil dieser Endlagersysteme sind die Endlagerbehälter, deren Gestaltung und Auslegung maßgeblich die Randbedingungen für die Transport- und Einlagerungstechnik vorgibt und zudem die Nachweise zur Betriebs- und Langzeitsicherheit entscheidend prägt. Daher ist es für die Behälterentwicklung erforderlich, die an Endlagerbehälter zu stellenden Anforderungen systematisch herzuleiten. Auf dieser Grundlage können anforderungsgerechte Endlagerbehälter zielgerichtet für die jeweils zu untersuchenden Endlagerstandorte in unterschiedlichen Wirtsgesteinen entwickelt werden.
Dieser Beitrag fasst die wesentlichen Ergebnisse des von BAM und BGE TECHNOLOGY GmbH im Zeitraum 2017 bis 2020 bearbeiteten und vom Bundesministerium für Wirtschaft und Energie (BMWi) geförderten Forschungsvorhabens KoBrA zusammen, die in einem Abschlussbericht und vier zugehörigen Teilberichten umfassend dokumentiert sind.
Dieser Bericht untersucht die im ersten Arbeitspaket ermittelten vorhandenen bzw. entwickelten Behälterkonzepte dahingehend, inwieweit die jeweiligen Behälterfunktionen unter den im zweiten und dritten Arbeitspaket ermittelten Randbedingungen und Einwirkungen den im dritten Arbeitspaket ermittelten Anforderungen an endlagerfähige Behälter in einem deutschen Endlager genügen. Zum anderen sollen, basierend auf den im zweiten Arbeitspaket ermittelten Randbedingungen und den im dritten Arbeitspaket hergeleiteten und zusammengestellten Anforderungen an die Endlagerbehälter, Vorschläge für mögliche generische Endlagerbehälter in den drei potenziellen Wirtsgesteinen Steinsalz, Tonstein und Kristallingestein erarbeitet werden. Die im ersten Arbeitspaket recherchierten Behälterkonzepte, deren Entwicklungslinien und zugrundeliegende Behälteranforderungen bilden hier den Ausgangspunkt für weitergehende Überlegungen hinsichtlich ihrer potenziellen Eignung für ein zukünftiges deutsches Endlager und zur Skizzierung generischer Konzepte für zukünftige Endlagerbehälter.
The major source of the anthropogenic platinum group element (PGE) emission is attributed to the use of catalytic converters in automobiles. This paper describes the work performed by three National Metrology Institutes (Laboratoire national de métrologie et dessais, by the Physikalisch-technische bundesanstalt, Bundesanatalt für materialforschung und prûfung), in the framework of the Joint Research Project 'PartEmission' under the European Metrology Research Program. An analytical procedure based on a cationic exchange protocol and the isotope dilution or standard addition using an Inductived Coupled Plasma Mass Spectrometer, ICP-MS, for the quantification of the elements Pt, Pd and Rh from automotive exhaust emissions is described. Results obtained on a road dust certified reference (BCR 723) material showed a good agreement with the certified values, at ng/g levels, and relative expanded uncertainties within the range of 7–10%. Analysis of filters impacted with automotive exhaust particle emissions (from a diesel engine) showed the amount of collected PGE at levels of 10–1000 pg/filter. Their quantifications followed the developed analytical protocol that had been carried out with relative expanded uncertainties in the range of a few per cent up to 20% per filter. Nevertheless, a lack of homogeneity between the filters was observed, making the comparison between the project partners difficult in the sake of the validation of their analytical procedures on real samples.
Scattering luminescent materials dispersed in liquid and solid matrices and luminescent powders are increasingly relevant for fundamental research and industry. Examples are luminescent nano- and microparticles and phosphors of different compositions in various matrices or incorporated into ceramics with applications in energy conversion, solid-state lighting, medical diagnostics, and security barcoding. The key parameter to characterize the performance of these materials is the photoluminescence/fluorescence quantum yield (Φf), i.e., the number of emitted photons per number of absorbed photons. To identify and quantify the sources of uncertainty of absolute measurements of Φf of scattering samples, the first interlaboratory comparison (ILC) of three laboratories from academia and industry was performed by following identical measurement protocols. Thereby, two types ofcommercial stand-alone integrating sphere setups with different illumination and detection geometries were utilized for measuring the Φf of transparent and scattering dye solutions and solid phosphors, namely, YAG:Ce optoceramics of varying surface roughness, used as converter materials for blue light emitting diodes. Special emphasis was dedicated to the influence of the measurement geometry, the optical properties of the blank utilized to determine the number of photons of the incident excitation light absorbed by the sample, and the sample-specific surface roughness. While the Φf values of the liquid samples matched between instruments, Φf measurements of the optoceramics with different blanks revealed substantial differences. The ILC results underline the importance of the measurement geometry, sample position, and blank for reliable Φf data of scattering the YAG:Ce optoceramics, with the blank’s optical properties accounting for uncertainties exceeding 20%.
The design and operation of an observational study on the profiles of volatile organic compounds (VOC) in the breath of 37 lung cancer patients and 23 healthy controls of similar age is outlined. The necessity to quantify each VOC considered as potential disease marker on basis of individual calibration is elaborated and the quality control measures required to maintain reproducibility in breath sampling and subsequent instrumental trace VOC analysis using SPME-GC-MS over a study period of 14 months are described. 24 VOC were quantified on basis of their previously suggested potential as cancer markers. The breath concentration levels of aromatic compounds was expectedly increased in smokers while lung cancer patients displayed significantly increased levels of oxygenated VOC such as aldehydes, 2-butanone and 1-butanol. Though sets of selected oxygenated VOC displayed sensitivities and specificities between 80 and 90% using linear discriminant analysis with leave-one-out cross validation the effective selectivity of the breath VOC approach with regard to cancer detection is clearly limited. Results were discussed against the background of the literature on volatile cancer marker investigations and the prospects to link increased VOC levels in patients’ breath with approaches to employ sniffer dogs. Experiences from this study and the literature suggest that the current state of breath VOC based discrimination between cancer patients and healthy controls is hardly improvable. Observational studies tend to observe significant differences mostly in levels of certain oxygenated VOC but without resolution required for practical application. Any step towards practicable exploitation of VOC profile differences for illness detection would have to solve current restrictions set by the low and variable VOC concentrations. Further challenges are the technical complexity of studies involving breath sampling and possibly the limited capability of current analytical procedures to detect instable marker candidates.
Lanthanide-doped upconversion nanoparticles (UCNPs) are of great interest for biomedical applications. Currently, the applicability of UCNP bionanotechnology is hampered by the generally low luminescence intensity of UCNPs and inefficient energy Transfer from UCNPs to surface-bound chromophores used e.g. for photodynamic therapy or analyte sensing. In this work, we address the low-Efficiency issue by developing versatile core-Shell nanostructures, where high-concentration sensitizers and activators are confined in the core and Shell Region of representative hexagonal NaYF2:Yb,Er UCNPs. After Doping concentration optimization, the sensitizer-rich core is able to harvest/accumulate more excitation energy and generate almost one order of Magnitude higher luminescence intesity than conventional homogeneously doped nanostructures. At the same time, the activator Ions located in the Shell enable a ~6 times more efficient resonant energy Transfer from UCNPs to surface-bound acceptor dye molecules due to the short distance between donor-acceptor pairs. Our work provides new insights into the rational design of UCNPs and will greatly encrease the General applicability of upconversion nanotechnologies.
The very strong Lewis acid aluminium chlorofluo-ride (ACF) was loaded with anhydrous HF. The interactionbetween the surface of the catalyst and HF was investigatedusing a variety of characterization methods, which revealed he formation of polyfluorides. Moreover, the reactivity ofthe HF-loaded ACF towards the hydrofluorination of alkyneswas studied.
Arsenic and mercury are frequent contaminants in the environment and care must be taken to limit their entrance into the food chain. The toxicity of both elements strongly depends upon their speciation. Total amounts of As and Hg as well as their species were analyzed in muscle and liver of 26 fishes of seven freshwater fish species caught in the River Elbe. The median concentrations of As were 162 mg kg-1 w.w. in liver and 92 mg kg-1 w.w. in muscle. The median concentrations of total Hg were 241 mg kg-1 w.w. in liver and 256 mg kg-1 w.w. in muscle. While this level of Hg contamination of the freshwater fish in the River Elbe is significantly lower than 20 years ago, it exceeds the recommended environmental Quality standard of 20 mg Hg kg-1 w.w. by a factor of 5e50. However, the European maximum level of 500 mg Hg kg-1 for fish for human consumption is rarely exceeded. Arsenic-containing fatty acids and hydrocarbons were determined and partially identified in methanolic extracts of the fish by HPLC coupled in parallel to ICP-MS (element specific detection) and ESI-Q-TOF-MS (molecular structure detection). While arsenobetaine was the dominant As species in the fish, six arsenolipids were detected and identified in the extracts of liver tissue in common bream (Abramis brama), die (Leuciscus idus), asp (Aspius aspius) and northern pike (Esox lucius). Four arsenic-containing fatty acids (AsFA) and two arsenic-containing hydrocarbons (AsHC) are reported in freshwater fish for the first time. With respect to mercury the more toxic MeHgþ was the Major species in muscle tissue (>90% of total Hg) while in liver Hg2þ and MeHgþ were of equal importance. The results Show the high relevance of element speciation in addition to the determination of total element concentrations to correctly assess the burden of these two elements in fish.
Ray tracing boundary value problems: simulation and SAFT reconstruction for ultrasonic testing
(2016)
The application of advanced imaging techniques for the ultrasonic inspection of inhomogeneous anisotropic materials like austenitic and dissimilar welds requires information about acoustic wave Propagation through the material, in particular travel times between two Points in the material. Forward ray tracing is a popular approach to determine traveling paths and arrival times but is ill suited for inverse problems since a large number of rays have to be computed in order to arrive at prescribed end points.
In this contribution we discuss boundary value problems for acoustic rays, where the ray path between two given points is determined by solving the Eikonal equation. The implementation of such a two Point boundary value ray tracer for sound field simulations through an austenitic weld is described and its efficiency as well as the obtained results are compared to those of a forward ray tracer. The results are validated by comparison with experimental results and commercially available UT simulation tools.
As an application, we discuss an implementation of the method for SAFT (Synthetic Aperture Focusing Technique) reconstruction. The ray tracer calculates the required travel time through the anisotropic columnar grain structure of the austenitic weld. There, the formulation of ray tracing as a boundary value Problem allows a straightforward derivation of the ray path from a given transducer Position to any pixel in the reconstruction area and reduces the computational cost considerably.
The research project "Ultrasonic Net for Concrete Monitoring (UNeCOM)" aims at developing a methodology for an embedded ultrasonic network for the condition assessment of infrastructure constructions. Civil engineering structures made of concrete, which are located in tectonically active regions or undergo special loading conditions, may require continuous monitoring. It is important to assess the condition of the building and its stability to recognise and classify the effect of a seismic event or evolving damage at early stages before failure occurs. Embedded ultrasonic sensors offer the possibility to detect changes in the material and degradation mechanisms from inside the structure in areas which are difficult or impossible to inspect otherwise. In contrast to conventional ultrasonic testing methods, where the concrete surfaces are scanned with ultrasound probes, this new approach uses sensors, which are embedded into concrete, eliminating the effect of variable coupling conditions between sensors and concrete. This method allows an integral detection of changes in the concrete structure, for example due to seismic activities, to detect mechanical impacts, as well as degradation of the material due to overloading. Such methods have great relevance especially for the monitoring of constructions like power plants, bridges, offshore structures and other structures with high technical safety requirements. The sensor network can be controlled remotely through the internet which is also being used for data transfer. The embedded sensor network is designed to monitor structural damage and concrete degradation globally with high sensitivity.
The incorporation of ions in the lattice of hydroxyapatite alters significantly its structure.
Particularly, if anions such as trigonal borate units are accommodated in the lattice severe
distortions must occur around the substitution site because of different geometric shape, electric
charge and anion size. Solid-state NMR has been used to investigate this problem in detail for a
hydroxyapatite sample synthesized by high temperature solid state reaction. The results clearly
verify the existence of network distortions. Indeed, only about 1/3 of the total phosphate content
forms crystalline hydroxyapatite (also found in XRD) whereas the residual amount is contained in
two different phosphate sites with 31P chemical shifts of 5.5 ppm and 2.3 ppm, but broad resonances
lines suggesting disorder. Furthermore, a novel proton signal at -0.6 ppm was found which is
directly associated with the borate incorporation. No specific correlation of the two structurally
different borate units with the two phosphate groups is found.
The hydrothermal stability of SAPO-11 was studied in water of autogenous pressure as function of the temperature. SAPO-11 remained crystalline up to 190 °C. Thereby, it was observed, parent as well as hydrothermally treated samples showed similarities to the isotypic structure of zeolite AlPO-11 called here AELdry. After fully hydration of the samples, AELdry changed completely into a hydrated AELwet structure of another framework symmetry. The transition from calcined to hydrated state was reversible for both the parent and the hydrothermally treated samples. 27Al and 31P NMR MAS spectra showed a single resonance typical for AlPO4 type tetrahedra for the calcined parent and hydrothermally treated samples. Upon hydration, the single AlPO4 resonance signal split into three different signals as is the case for the corresponding 31P signals. By means of NH3-TPD measurement a loss of acidity was detected after the hydrothermal treatment as follows from a framework desilication. Nitrogen and water adsorption decreased systematically. At 210 °C a non-zeolitic, non-porous phase was irreversibly formed. The XRD pattern of this phase shows resemblance to a synthetic aluminium phosphate of the tridymite structure type.
Methodologies on fire risk analysis in road tunnels consider numerous factors affecting risks (risk indicators) and express the results by risk measures. But only few comprehensive studies on effects of risk indicators on risk measures are available. For this reason, this study quantifies the effects and highlights the most important risk indicators with the aim to Support further developments in risk analysis. Therefore, a system model of a road tunnel was developed to determine the risk measures.
The system model can be divided into three parts: the fire part connected to the fire model Fire Dynamics Simulator (FDS); the evacuation part connected to the evacuation model FDS+Evac; and the frequency part connected to a model to calculate the frequency of fires. This study shows that the parts of the system model (and their most important risk indicators) affect the risk measures in the following order: first, fire part (maximum heat release rate); second, evacuation part (maximum preevacuation time); and, third, frequency part (specific frequency of fire). The plausibility of These results is discussed with view to experiences from experimental studies and past fire incidents.
Conclusively, further research can focus on these most important risk indicators with the aim to optimise risk analysis.
We present a systematic study on the effect of surface ligands on the luminescence properties and colloidal stability of β-NaYF4:Yb3+,Er3+ upconversion nanoparticles (UCNPs), comparing nine different surface coatings to render these UCNPs water-dispersible and bioconjugatable. A prerequisite for this study was a large-scale synthetic method that yields ~2 g per batch of monodisperse oleate-capped UCNPs providing identical core particles. These ~23 nm sized UCNPs display an upconversion quantum yield of ~0.35% when dispersed in cyclohexane and excited with a power density of 150 W cm-2, underlining their high quality. A comparison of the colloidal stability and luminescence properties of these UCNPs, subsequently surface modified with ligand exchange or encapsulation protocols, revealed that the ratio of the green (545 nm) and red (658 nm) emission bands determined at a constant excitation power density clearly depends on the surface chemistry. Modifications relying on the deposition of additional (amphiphilic) layer coatings, where the initial oleate coating is retained, show reduced non-radiative quenching by water as compared to UCNPs that are rendered water-dispersible via ligand exchange. Moreover, we could demonstrate that the brightness of the upconversion luminescence of the UCNPs is strongly affected by the type of surface modification, i.e., ligand exchange or encapsulation, yet hardly by the chemical nature of the ligand.
We have studied the mechanisms of water-based quenching of the upconversion photoluminescence of upconverting nanophosphors (UCNPs) via luminescence decay measurements for a better understanding of the non-radiative deactivation pathways responsible for the relatively low upconversion luminescence efficiency in aqueous solutions. This included both upconversion luminescence measurements and the direct excitation of emissive energy states of Er3+ and Yb3+ dopants in NaYF4:Yb3+,Er3+ UCNPs by measuring the decays at 550 and 655 nm upon 380 nm excitation and at 980 nm upon 930 nm excitation, respectively. The luminescence intensities and decays were measured from both bare and silanized NaYF4:Yb3+,Er3+ and NaYF4:Yb3+,Tm3+ UCNPs in H2O and D2O. The measurements revealed up to 99.9% quenching of the upconversion photoluminescence intensity of both Er3+ and Tm3+ doped bare nanophosphors by water. Instead of the multiphonon relaxation of excited energy levels of the activators, the main mechanism of quenching was found to be the multiphonon deactivation of the Yb3+ sensitizer ion caused by OH-vibrations on the surface of the nanophosphor. Due to the nonlinear nature of upconversion, the quenching of Yb3+ has a higher order effect on the upconversion emission intensity with the efficient Yb–Yb energy migration in the ~35 nm nanocrystals making the whole nanophosphor volume susceptible to surface quenching effects. The study underlines the need of efficient surface passivation for the use of UCNPs as labels in bioanalytical applications performed in aqueous solutions.
This study compares the mercury distribution in the vapor phase, the phosphor powder and the glass matrix of new and spent fluorescent lamps. The spent fluorescent lamps were obtained at the collection yards of a public waste management company in Hamburg, Germany. An innovative systematic sampling method is utilized to collect six spent and eight corresponding new, off-the-shelf fluorescent lamp samples. The efficiency of several acid digestion methods for the determination of the elemental composition was studied and elemental mass fractions of K, Na, Y, Ca, Ba, Eu, Al, Pb, Mg, Hg, and P were measured. The study also finds aqua regia to be the best reagent for acid digestion. However, no significant difference in mercury distribution was found in the different phases of the new and spent fluorescent lamps.
A first pilot study on the sorption of environmental pollutants on various microplastic materials
(2017)
With the drastic increase in plastic production, the input of plastic particles into the environment has become a recognised problem.
Xenobiotics are able to sorb to polymer materials, and this process is further enhanced where they Encounter microplastics (plastic fragments <5 mm). In this work we studied the sorption of metformin, a type-2 diabetes drug, and difenoconazole, a fungicide, onto the virgin polymer materials polyamide (PA), polypropylene (PP), and polystyrene (PS). Additionally, PP was cryo-milled and PA was treated with acid to investigate the influence of an increase in surface area and chemical modification. The material properties were also studied by dynamic scanning calorimetry (DSC), gel permeation chromatography (GPC) and Fourier transform infrared spectroscopy (FTIR). Sorption experiments were performed on the basis of a full factorial design examining the effect of agitation, pH value, and salinity. Experimental results showed that difenoconazole sorbs readily to all microplastics, whereas the more polar analyte metformin did not show any affinity to the materials used. For difenoconazole the governing factor in all cases is agitation, while both pH and salinity exhibited only a slight influence. The modification of polymers leads to enhanced sorption, indicating that an increase in surface area (cryo-milled PP) or inner volume (acid-treated PA) strongly favours adsorption. Moreover, long-term experiments demonstrated that the time until equilibrium is reached depends strongly on the particle size.
Drug therapy for diabetes mellitus has increased significantly in recent years. 1,1-Dimethylbiguanide hydrochloride (metformin) is the most common drug used for the treatment of diabetes. Metformin is not metabolized in the human body and enters thewater cycle via sewage.
A new gas chromatography-mass spectrometry (GC-MS) method has been developed which enables the quantification of metformin in surface water samples even at low concentrations in the ng L-1 range.
A solid phase extraction (SPE) method for the preconcentration of metformin and the internal standard 1-butylbiguanide (buformin) was established, and the method parameters such as the composition and volume of the eluent were optimized. Derivatization of metformin and
buformin was obtained by using n-methyl-bis (trifluoroacetamide)(MBTFA). The reaction conditions of the derivatization, such as the reaction temperature and volume of the derivatization agent, were evaluated. The limit of detection (LOD) and limit of quantification (LOQ) were determined to be 3.9 ng L-1 and 12 ng L-1 in surface water samples. Linearity was shown over a concentration range of 10–50 ng L-1. The good performance of the method was demonstrated by comparison with a liquid chromatography tandemmass spectrometry (LC-MS/MS) method. The results indicate that the GC-MS method is a reliable and sensitive alternative for the quantification of metformin in surface water.
1.
At the core of luminescence color and lifetime Tuning of rare earth doped upconverting nanoparticles (UCNPs), is the understanding of the Impact of the particle architecture for commonly used sensitizer (S) and activator (A) Ions. In this respect, a series of core@Shell NaYF4 UCNPs doped with Yb3+ and Ho3+ ions are presented here, where the same dopant concentrations are distributed in different particle architectures following the scheme: YbHo core and YbHo@..., ...@YbHo, Yb@Ho, Ho@Yb, YbHo@Yb, and Yb@YbHo core-Shell NPs. As refealed by quantitative steady-state and time-resolved luminescence studies, the relative spatial Distribution of the A and S ions in the UCNPs and their protection from surface quenching has a critical Impact on ther luminescence characteristics. Although the increased amount of Yb3+ Ions boosts UCNP Performance by amplifying the Absorption, the Yb3+ ions can also efficiently dissipate the energy stored in the material through energy Migration to the surface, thereby reducing the Overall energy Transfer Efficiency to the activator ions. The results provide yet another proof that UC Phosphor chemistry combined with materials Engineering through intentional core@shell structures may help to fine-tune the luminescence Features of UCNPs for their specific future applications in biosensing, bioimaging, photovoltaics, and Display technologies.
Mittels Propan-Brennern mit einer Brennerleistung 750 kW wurden in einer U-Bahn-Station Heißgasversuche durchgeführt und die zeitlichen und örtlichen Verteilungen der physikalischen Größen (Stoffkonzentration, Temperatur und Rauchgasdichte) erfasst. Laborversuche sowie die Feldversuche sind Validierungsgrundlage für ANSYS CFX und FDS und die später im Rechenmodell der U-Bahn-Station zur Untersuchung der Grundströmung und Rauchausbreitung verwendeten mathematisch-physikalischen Modelle. Der Aufsatz stellt das Projekt ORPHEUS vor und diskutiert die ersten Ergebnisse.
In urban areas the demand for public transportation is constantly growing. Underground railway systems overcome the problem of limited space on the ground and are therefore one of the most powerful systems in urban public transportation. These facilities can be very complex and are used by a large amount of passengers. Therefore, it is important to maintain the safety for people and buildings. Especially in the case of fire or arson attack.
This paper focusses on a fire scenario in a complex subway station for different weather conditions. The purpose is to identify the influences of different weather conditions on the smoke spread and the ability of self-rescue in case of a burning luggage.
The evaluation of the fire simulations will focus on toxicity and visibility taking into account the FED concept.
A probabilistic approach for finite element analysis (FEA) for tunnel linings exposed to the nominal fire is presented. The probabilistic FEA accounted for the uncertainties distributions tied to the conductivity and specific heat as well as of the compressive strength, tensile strength, Young’s modulus, and ultimate strain in compression. To get an understanding on the influence of different probability density functions on the distribution of maximum displacements of the tunnel lining, a sensitivity analysis was performed. Four sets of FEAs were carried out with different probability distributions of the conductivity, the specific heat, and the compressive strength of the concrete, respectively. An experimental design based on a Latin Hypercube Sampling algorithm was performed to define the input parameters which describe each analysis case. A reliability analysis was executed considering a limit state function based on the temperature-dependent ultimate strain. The results show that, depending on the distribution adopted, the standard deviation of the maximum displacements can vary up to 47,4% of the minimum standard deviation. The large standard deviation is associated with the possibility of a greater displacement and, hence, to a structure more vulnerable to fire.
Probabilistic thermo-Mechanical analysis of a concrete tunnel lining subject to fire The probability distributions of the parameters related to the thermal analysis was considered in order to study the variability of the results and to carry out a reliability analysis. This assessment considered as random variables the thermo-mechanical properties of the concrete, the maximum heat release rate (HRR), the duration of the period of maximum HRR, the convective coefficient, the emissivity at the surface exposed to the fire, the air velocity within the tunnel, and the initial fire radius. The temperature-time curve was described by a correlation. An experimental design based on a Latin Hypercube Sampling algorithm was performed to define the input parameters to each analysis case. The definition of a limit state function based on the punctual strain status has permitted to carry out a reliability analysis.
The research project focuses on tackling the detection, measurement, and elimination of per- and polyfluoroalkyl substances (PFAS) from polluted groundwater, with a particular emphasis on addressing short (C4-C7) and ultrashort (C1-C3) chain PFAS. Given the widespread use of PFAS in various products, they are commonly found in groundwater near industrial and military sites in Germany and Israel. Moreover, recent regulations limiting the use of long chain PFAS have led industries to shift towards shorter chain alternatives. Hence, our efforts are geared towards refining detection, quantification, and removal methods for short and ultrashort chain PFAS. In terms of detection, ww are developing passive sampling devices capable of collecting and tracking the temporal distribution of PFAS species in groundwater. This will enable us to analyze contaminations in German and Israeli groundwater using cutting-edge analytical techniques. Additionally, contaminated groundwater will undergo a two-stage treatment process aimed at concentrating the relatively low PFAS concentrations using innovative membrane technologies such as closed-circuit reverse osmosis and mixed matrix composite nanofiltration membrane adsorbers. Subsequently, the streams containing higher PFAS concentrations will be treated through coagulation, with the remaining PFAS being adsorbed onto carbonaceous nanomaterials. The outcome of this research will include the creation of advanced tools for detecting, measuring, and eliminating PFAS from polluted groundwater, while also enhancing our understanding of the scope of these contaminations.
This paper describes the production and characteristics of the nanoparticle test materials prepared for common use in the collaborative research project NanoChOp (Chemical and optical characterization of nanomaterials in biological systems), in casu suspensions of silica nanoparticles and CdSe/CdS/ZnS quantum dots (QDs). This paper is the first to illustrate how to assess whether nanoparticle test materials meet the requirements of a "reference material" (ISO Guide 30, 2015) or rather those of the recently defined category of "representative test material (RTM)" (ISO/TS 16195, 2013). The NanoChOp test materials were investigated with small-angle X-ray scattering (SAXS), dynamic light scattering (DLS), and centrifugal liquid sedimentation (CLS) to establish whether they complied with the required monomodal particle size distribution. The presence of impurities, aggregates, agglomerates, and viable microorganisms in the suspensions was investigated with DLS, CLS, optical and electron microscopy and via plating on nutrient agar. Suitability of surface functionalization was investigated with attenuated total reflection Fourier transform infrared spectrometry (ATR-FTIR) and via the capacity of the nanoparticles to be fluorescently labeled or to bind antibodies. Between-unit homogeneity and stability were investigated in terms of particle size and zeta potential. This paper shows that only based on the outcome of a detailed characterization process one can raise the status of a test material to RTM or reference material, and how this status depends on its intended use.
The use of ashes from municipal solid waste incineration as secondary building materials is an important pillar for the circular economy in Germany. However, leaching of potential toxic elements from these materials must be at environmentally acceptable levels. Normally, a three-month ageing period immobilizes most hazardous heavy metals, but antimony (Sb) and vanadium (V) showed previously unusual leaching. In order to clarify the mechanisms, we analyzed the Sb and V species in various bottom and fly ashes from municipal waste incineration by XANES spectroscopy. Antimony oxidizes from Sb(+ III) species used as flame retardants in plastics to Sb(+ V) compounds during waste incineration. However, owing to the similarity of different Sb(+ V) compound in the Sb K- and L-edge XANES spectra, it was not possible to accurately identify an exact Sb(+ V) species. Moreover, V is mainly present as oxidation state + V compound in the analyzed ashes. However, the coarse and magnetic fraction of the bottom ashes contain larger amounts of V(+ III) and V(+ IV) compounds which might enter the waste incineration from vanadium carbide containing steel tools. Thus, Sb and V could be critical potential toxic elements in secondary building materials and long-term monitoring of the release should be taken into account in the future.
The influence of distinct carbon based nanofillers: expanded graphite (EG), conducting carbon black (CB), thermally reduced graphene oxide (TRGO) and multi-walled carbon nanotubes (CNT) on the thermal, dielectric, electrical and rheological properties of polybutylene terephthalate (PBT) was examined. The glass transition temperature (Tg) of PBT nanocomposites is independent of the filler type and content. The carbon particles act as nucleation agents and significantly affect the melting temperature (Tm), the crystallization temperature (Tc) and the degree of crystallinity of PBT composites. PBT composites with EG show insulating behaviour over the tested concentration range of 0.5 to 2 wt.-% and hardly changed rheological behaviour. CB, CNT and TRGO induce electrical conductivity to their particular PBT composites by forming a conducting particle network within the polymer matrix. CNT reached the percolation threshold at the lowest concentration (<0.5 wt.-%), followed by TRGO (<1 wt.-%) and CB (<2 wt.-%). With the formation of a particle network, the flow behaviour of composites with CB, CNT and TRGO is affected, i.e., a flow limit occurs and the melt viscosity increases. The degree of influence of the carbon nanofillers on the rheological properties of PBT composites follows the same order as for electrical conductivity. Electrical and rheological results suggest an influence attributed to the particle dispersion, which is proposed to follow the order of EG<< CB<TRGO<CNT.
Pseudomonas aeruginosa is an opportunistic pathogen of considerable medical importance, owing to its pronounced antibiotic tolerance and association with cystic fibrosis and other life-threatening diseases. The aim of this study was to highlight the genes responsible for P. aeruginosa biofilm tolerance to antibiotics and thereby identify potential new targets for the development of drugs against biofilm-related infections. By developing a novel screening approach and utilizing a public P. aeruginosa transposon insertion library, several biofilm-relevant genes were identified. The Pf phage gene (PA0720) and flagellin gene (fliC) conferred biofilm-specific tolerance to gentamicin. Compared with the reference biofilms, the biofilms formed by PA0720 and fliC mutants were completely eliminated with a 4-fold-lower gentamicin concentration. Furthermore, the mreC, pprB, coxC, and PA3785 genes were demonstrated to play major roles in enhancing biofilm tolerance to gentamicin. The analysis of biofilm-relevant genes performed in this study provides important novel insights into the understanding of P. aeruginosa antibiotic tolerance, which will facilitate the detection of antibiotic resistance and the development of antibiofilm strategies against P. aeruginosa.
Ananion-dopedaluminiumchlorofluoride AlCl0.1F2.8(OTeF5)0.1(ACF-teflate) was synthesized.The material contains pentafluor-oorthotellurate(teflate)groups, which mimic fluoride ions electronically, but are sterically more demanding. They are embedded into the amorphous structure. The latter was studied by PDF analysis, EXAFS data and MAS NMR spectroscopy. The mesoporous powder is a Lewis superacid, and ATR-IR spectra of adsorbed CD3CN reveal a blue-shift of the adsorption band by73 cm-1, which is larger than the shift for SbF5. Remarkably,ACF-teflate catalyzes dehydrofluorination reactions of mono-fluoroalkanes to yield olefins in C6D6. In these cases,no Friedel-Crafts products were formed.
Luminescent solar concentrators (LSC) allow to obtain renewable energy from building integrated photovoltaic systems. As promising efficient and long-term stable LSC fluorophores semiconductor nanocrystals like Quantum dots (QDs) with size and composition tunable optoelectronic properties have recently emerged. The most popular II/VI or IV/VI semiconductor QDs contain, however, potentially hazardous cadmium or lead ions, which is a bottleneck for commercial applications. A simple aqueous based, microwaveassisted synthesis for environmentally friendly and highly emissive AgInS2/ ZnS QDs is developed using 3-mercaptopropionic acid (MPA) and glutathione (GSH) and their incorporation into polylaurylmethacrylate (PLMA) polymer slabs integrable in LSC devices (10.4 × 10.4 × 0.2 cm3, G = 12.98).
With this simple approach, optical power efficiencies (OPE) of 3.8% and 3.6% and optical quantum efficiencies (OQE) of 24.1% and 27.4% are obtained, which are among the highest values yet reported.
We synthesized and characterized a set of ultrasmall hexagonal-phase NaGdF4: 20% Yb3+, 2% Er3+ upconversion nanoparticles with core diameters of 3.7 ± 0.5 nm. In order to assess passivation effects and the influence of possible core−shell intermixing and to identify optimum particle structures for combined imaging in the visible and near-infrared (vis−NIR: 410−850 nm) and short-wave infrared (SWIR: 1520 nm), NaYF4 shells of varying thicknesses (monolayer to 10 nm) were introduced and the influence of this parameter on the upconversion and downshifting photoluminescence of these particles was studied at different excitation power densities. This included excitation power-dependent emission spectra, slope factors, quantum yields, and excited state decay kinetics. These measurements revealed enhancement factors of the upconversion quantum yield of >10 000 in the low power region and an excitation power density-independent quantum yield of the downshifted emission at 1520 nm between 0.1 and 14%. The optimized shell thickness for combined vis and SWIR imaging was identified as 5 nm. Moreover, lifetimes and quantum yields can be continuously tuned by shell thickness which can be exploited for lifetime multiplexing and encoding. The fact that we did not observe a saturation of the upconversion quantum yield or the excited state decay kinetics with increasing shell thickness is ascribed to a strong intermixing of the active core with the inert shell during the shelling procedure. This indicates the potential of spectroscopic tools to detect cation intermixing.
Im Forschungsvorhaben KoBrA werden Anforderungen an Endlagerbehälter für hochradioaktive Abfälle erstmals systematisch und unter Berücksichtigung des internationalen Standes von Wissenschaft und Technik hergeleitet. Parallel werden die behälterrelevanten Randbedingungen und Beanspruchungsgrößen für Endlagerbehälter in den drei potenziellen Wirtsgesteinen Steinsalz, Tonstein und Kristallingestein ermittelt. Darauf aufbauend werden die zur Erfüllung der Anforderungen unter den gegebenen Einwirkungen und Beanspruchungen notwendigen Behälterfunktionen bestimmt und erste Konzeptideen für zukünftige Endlagerbehälter diskutiert bzw. entwickelt.
Nanocrystalline basaluminite [Al4OH10(SO4)(H2O)3–5] and Aggregation of the e-Keggin polyoxocation [Al12(AlO4)(OH)24(H2O)12]7+, referred to as Al13, have both been described to form in acid mine Drainage environments. Although the chemical composition is quite similar, their crystalline varieties significantly differ, demonstrating that various types of Al-hydroxysulfates can form under similar conditions and that their respective formation is not fully understood yet. Here, we report the occurrence of nanocrystalline precipitates that form naturally in a small alpine catchment in Switzerland where an acidic mountainous stream (pH 4) is neutralized successively after mixing with several neutral tributaries. The stepwise neutralization in conjunction with the large amount of precipitates provide an ideal setting for obtaining new insights into (i) the structure of naturally forming Al-hydroxysulfates, (ii) their formation mechanism, (iii) their role in controlling the solubility of Al, and (iv) their ability to lower the mobility of As. Synchrotron-based high-energy X-ray diffraction and subsequent pair distribution function analyses demonstrate that these precipitates are structurally identical to basaluminite samples obtained from acid mine drainage sites. In contrast, only minor amounts of tetrahedrally coordinated Al, as present in Al13, were identified by nuclear magnetic resonance spectroscopy. The precipitates are further characterized by elevated As concentrations up to 600 lg/g, whereas other heavy metals are at background concentrations only. Given the low As concentrations in the stream from which precipitation occurs (<0.03 mg/L), high As concentrations confirm that basaluminite serves as a highly efficient As sink, which is attributed to its high anion-exchange capacity. Chemical analysis of streamwater samples in combination with geochemical modeling show that precipitation occurs instantaneously upon mixing with neutral streams.
Moreover, our data reveal that the precipitation of basaluminite exerts a strong solubility control on dissolved Al concentrations as manifested by the quasi-constant basaluminite ion activity product observed during neutralization from pH 5 to pH 5.9. We hypothesize that in our field system, high fluoride and sulfate concentrations on the order of 100 and 1–2 mg/L,
This paper presents a probabilistic methodology based on the thermo-mechanical finite elements analysis to investigate the impact of the variability of the thermal properties of the concrete in the fire safety of structures. This is meant to evaluate if characteristic values or safety factors for the conductivity and specific heat are
required during the semi-probabilistic structural fire safety assessment. To illustrate the use of the proposed methodology, this work includes a case-study with a tunnel lining which considers the uncertainties related to the thermal and mechanical properties of the concrete, the soil load, and the temperatures described by the
standard temperature-time curve. Two failure criteria are considered: one was the maximum temperature of 300 °C at the reinforcement and the other based on the temperature-dependent strength as provided in the Eurocode EN 1992-1-2. Several finite element analyses are performed. The design of experiments is executed by a Correlation Latin Hypercube Sampling. The calculated probability of failure has different values depending on the adopted failure criteria. A sensitivity analysis using the Spearman's rank correlation coefficient was carried out and demonstrates that the uncertainty related to the specific heat has the greatest impact on the results.
This paper presents a probabilistic methodology based on the thermo-mechanical finite elements analysis to investigate the impact of the variability of the thermal properties of the concrete in the fire safety of structures. This is meant to evaluate if characteristic values or safety factors for the conductivity and specific heat are required during the semi-probabilistic structural fire safety assessment. To illustrate the use of the proposed methodology, this work includes a case-study with a tunnel lining which considers the uncertainties related to the thermal and mechanical properties of the concrete, the soil load, and the temperatures described by the standard temperature-time curve. Two failure criteria are considered: one was the maximum temperature of 300 °C at the reinforcement and the other based on the temperature-dependent strength as provided in the Eurocode EN 1992-1-2. Several finite element analyses are performed. The design of experiments is executed by a Correlation Latin Hypercube Sampling. The calculated probability of failure has different values depending on the adopted failure criteria. A sensitivity analysis using the Spearman's rank correlation coefficient was carried out and demonstrates that the uncertainty related to the specific heat has the greatest impact on the results.
Structuring over many length scales is a design strategy widely used in Nature to create materials with unique functional properties. We here present a comprehensive analysis of an adult sea urchin spine, and in revealing a complex, hierarchical structure, show how Nature fabricates a material which diffracts as a single crystal of calcite and yet fractures as a glassy material. Each spine comprises a highly oriented array of Mg-calcite nanocrystals in which amorphous regions and macromolecules are embedded. It is postulated that this mesocrystalline structure forms via the crystallization of a dense array of amorphous calcium carbonate (ACC) precursor particles. A residual surface layer of ACC and/or macromolecules remains around the nanoparticle units which creates the mesocrystal structure and contributes to the conchoidal fracture behavior. Natures demonstration of how crystallization of an amorphous precursor phase can create a crystalline material with remarkable properties therefore provides inspiration for a novel approach to the design and synthesis of synthetic composite materials.
This study reports three new crystalline aluminum isopropoxide oxide fluorides with molar ratios of Al:F equal to 1:1 and 1:1.25. These are the first three representatives isolated without the incorporation of external donor molecules. Compound 1 Al4F4(µ4-O)(µ-O'Pr)5[H(O'Pr)2] contains a tetranuclear unit consisting of two different five fold coordinated AlFO4-units, with F exclusively in the terminal position. Compound 2, Al4F4(µ4-O)(µ-O'Pr)5[H(O'Pr)2]·Al5F5(µ5-O)(µ-O'Pr)8, contains both a tetranuclear unit (as in 1) and a pentanuclear Al-unit. Al-atoms in the latter are five- and six fold coordinated. Compound 3, Al16F20(µ4-O)4(µ-O'Pr)20·2('PrOH), exhibits a slightly higher fluorination degree and contains an oligomeric chain of four F-linked tetranuclear Al-units. In addition to X-ray structure analysis, compound 1 was characterized by different solid state MAS NMR techniques, including 27Al triple quantum MAS NMR and 1H, 1H→13C CP, 19F and 27Al MAS NMR. On the basis of the collected data, a reliable decomposition of 27Al single pulse MAS NMR spectra and an unambiguous assignment of the resonances to the respective structural AlFO4-units are given. The new crystalline aluminum isopropoxide oxide fluorides are direct evidence of the fluorolytic sol–gel mechanism previously discussed.
Calcium, strontium, and barium copper silicates are demonstrated to possess valuable photophysical properties which make them particularly attractive for application in optical chemosensors. Several examples of sensing materials based on these phosphors are provided. Particularly, broad excitation and near-infrared emission makes them ideal candidates for the preparation of ratiometric sensors based on absorption-based indicators. Due to their excellent chemical and photochemical stability and high brightness, these phosphors can serve as reference for fluorescent indicators to enable ratiometric intensity or dually lifetime referenced measurements. Finally, the moderate temperature dependence of the luminescence decay time enables intrinsic temperature compensation of the sensing materials at ambient temperatures. The improved sensitivity at temperatures above 100 °C makes these new materials promising candidates for high-temperature thermographic phosphors.
The fluorescence quantum yield (QY) of CdSe dot/CdS rod (DR) nanoparticle ensembles is dependent on the Shell growth and excitation wavelength. We analyze the origin of this dependency by comparing the optical properties of DR ensembles to the results obtained in single-particle experiments. On the Ensemble level, we find that the QY of DRs with shell lengths shorter than 40 nm exhibits no dependence on the excitation wavelength, whereas for DRs with shell lengths longer than 50 nm, the QY significantly decreases for excitation above the CdS band gap. Upon excitation in the CdSe core, the ensemble QY, the fluorescence wavelength, and the fluorescence blinking behavior of individual particles are only dependent on the radial CdS shell thickness and not on the CDs shell length. If the photogenerated excitons can reach the CdSe core region, the fluorescence properties will be dependent only on the surface passivation in close vicinity to the CdSe core. The change in QY upon excitation above the band gap of CdS for longer DRs cannot be explained by nonradiative particles because the ratio of emitting DRs is found to be independent of the DR length. We propose a model after which the decrease in QY for longer CdS shells is due to an increasing fraction of nonradiative exciton recombination within the elongated shell. This is supported by an effective-mass-approximation-based calculation, which suggests an optimum length of DRs of about 40 nm, to combine the benefit of high CdS absorption cross section with a high fluorescence QY.
For a comprehensive safety assessment of stationary lithium-ion-battery applications, it is necessary to better understand the consequences of thermal runaway (TR). In this study, experimental tests comprising twelve TR experiments including four single-cell tests, two cell stack tests and six second-life module tests (2.65 kW h and 6.85 kW h) with an NMC-cathode under similar initial conditions were conducted. The temperature (direct at cells/modules and in near field), mass loss, cell/module voltage, and qualitative vent gas composition (Fourier transform infrared (FTIR) and diode laser spectroscopy (DLS) for HF) were measured. The results of the tests showed that the battery TR is accompanied by severe and in some cases violent chemical reactions. In most cases, TR was not accompanied by pregassing of the modules. Jet flames up to a length of 5 m and fragment throwing to distances to more than 30 m were detected. The TR of the tested modules was accompanied by significant mass loss of up to 82%. The maximum HF concentration measured was 76 ppm, whereby the measured HF concentrations in the module tests were not necessarily higher than that in the cell stack tests.
Subsequently, an explosion of the released vent gas occurred in one of the tests, resulting in the intensification of the negative consequences. According to the evaluation of the gas measurements with regard to toxicity base on the “Acute Exposure Guideline Levels” (AEGL), there is some concern with regards to CO, which may be equally as important to consider as the release of HF.
A new metallosilicate based on yttrium was synthesized and characterized by XRD, FT-IR, 29Si MAS-NMR, and 89Y MAS-NMR. The mixed framework of the material was confirmed by the detection of distinct chemical shift groups using 29Si MAS-NMR (at -82 to -87 ppm, -91 to -94 ppm, -96 to -102 ppm, and -105 to -108 ppm), as well as four distinct chemical shifts in the 89Y MAS-NMR spectrum (at -89, -142, -160, and -220 ppm). Adsorption and kinetic analyses indicated the potential of the new material for the removal of lead and cadmium from aqueous media. The adsorption results for lead indicated that dynamic equilibrium was reached after five hours, with total lead removal of around 94 %, while for cadmium it was reached in the first hour, with total Cadmium removal of around 74 %. The adsorptions of lead and cadmium were modeled using pseudo-first order (PFO) and pseudo-second order (PSO) kinetic models. Although both models provided high R2 values (0.9903 and 0.9980, respectively), the PSO model presented a much lower χ2 red value (4.41×10−4), compared to the PFO model (2.12×10−3), which indicated that the rate-limiting step was probably due to the chemisorption of lead from the solution onto the yttrium-based metallosilicate.
Ti-Al-Nb based intermetallic layers of sufficient quality and thickness were obtained by non-vacuum electron beam cladding on the surfaces of Ti workpieces. Optical microscopy and X-ray tomography did not reveal any dramatical defects in the structure of cladded layers. X-ray diffraction as well as scanning and transmission electron microscopy were applied to thoroughly investigate the structure and phase composition of coatings. It was found that non-equilibrium cooling conditions of coatings provided by fast removal of heat to untreated Ti substrate after the electron beam cladding was terminated induced the proceeding of metastable phase transformations. For example, γ-phase formation was suppressed in these coatings. In coatings with 8 and 20 at.% Nb (46 and 43% Al respectively) along with ordered with α2, formation of disordered solution of the alloying elements in α-Ti took place. In high-Nb alloys β(B2) phase has undergone the diffusionless transformation to ω’, which is the intermediate phase in β → ω and the coating with the maximum Nb content characterized by appearance of γ1 as a main phase. ω-phase had negative influence to hardness and wear resistance of coatings, however, generally this paremeter increased in 1.3–1.75 times compared to cp-Ti. The high temperature creep and oxidation properties decreased proportionally with increasing Nb and decreasing Al content in the cladded layers.
The use of highly water-soluble phosphorus (P) fertilizers can lead to P fixation in the soil, reducing fertilization efficiency. Waste-derived, low water-solubility sources can potentially increase sugarcane’s P uptake compared to triple superphosphate by reducing adsorption to the soil.
Aims:We aimed to test struvite, hazenite, and AshDec® for their agronomic potential as recycled fertilizers for sugarcane production in a typical tropical soil.We hypothesize that these sources can reduce P fixation in the soil, increasing its availability and sugarcane’s absorption.
Methods: In a greenhouse pot experiment, two consecutive sugarcane cycles, 90 days each, were conducted in a Ferralsol. The recovered sources struvite, hazenite, AshDec®, and the conventional triple superphosphate were mixed in the soil in three P doses (30, 60, and 90 mg kg–1), aside a control (nil-P). At both harvests, sugarcane number of sprouts, plant height, stem diameter, dry mass yield, shoot phosphorus, and soil P fractionation were investigated.
Results: At 90 days, struvite and hazenite performed better for dry mass yield (70.7 and 68.3 g pot–1, respectively) than AshDec® and triple superphosphate (59.8 and 57.4 g pot–1, respectively) and for shoot P, with 98.1, 91.6, 75.6, and 66.3 mg pot–1, respectively. At 180 days, struvite outperformed all treatments for dry mass yield (95.3 g pot–1) and AshDec® (75.5 mg pot–1) for shoot P. Struvite was 38% and hazenite 21% more efficient than triple superphosphate in P uptake, while AshDec® was 6% less efficient. Soil had higher labile P under struvite, hazenite, and AshDec® than triple superphosphate by the end of the first cycle, while only the later increased nonlabile P by the end of the experiment (180 days).
Conclusions:Waste-derived P sources were more efficient in supplying P for sugarcane and delivering labile P in 180 days than triple superphosphate.
Single particle imaging of upconversion nanoparticles (UCNPs) has typically been realized using hexagonal (β) phase lanthanide-doped sodium yttrium fluoride (NaYF4) materials, the upconversion luminescence (UCL) of which saturates at power densities (P) of several hundred W cm−2 under 980 nm nearinfrared (NIR) excitation. Cubic (α) phase UCNPs have been mostly neglected because of their commonly observed lower UCL efficiency at comparable P in ensemble level studies. Here, we describe a set of sub-15 nm ytterbium-enriched α-NaYbF4:Er3+@CaF2 core/shell UCNPs doped with varying Er3+ concentrations (5–25%), studied over a wide P range of ∼8–105 W cm−2, which emit intense UCL even at a low P of 10 W cm−2 and also saturate at relatively low P. The highest upconversion quantum yield (ΦUC) and the highest particle brightness were obtained for an Er3+ dopant concentration of 12%, reaching the highest ΦUC of 0.77% at a saturation power density (Psat) of 110 W cm−2. These 12%Er3+-doped core/shell UCNPs were also the brightest UCNPs among this series under microscopic conditions at high P of ∼102–105 W cm−2 as demonstrated by imaging studies at the single particle level. Our results underline the potential applicability of the described sub-15 nm cubic-phase core/shell UCNPs for ensemble- and single particle-
level bioimaging.
Conventional phosphate fertilizers are usually highly water-soluble and rapidly solubilize when moistened by the soil solution. However, if this solubilization is not in alignment with plants demand, P can react with the soil colloidal phase, becoming less available over time. This is more pronounced in acidic, oxidic tropical soils, with
high P adsorption capacity, reducing the efficiency of P fertilization. Furthermore, these fertilizers are derived from phosphate rock, a non-renewable resource, generating an environmental impact. To assess these concerns, waste-recycled P sources (struvite, hazenite and AshDec®) were studied for their potential of reducing P Fixation by the soil and improving the agronomic efficiency of the P fertilization. In our work, we compared the solubilization dynamics of struvite, hazenite, AshDec® to triple superphosphate (TSP) in a sandy clay loam Ferralsol, as well as their effect on solution pH and on soil P pools (labile, moderately-labile and non-labile) via an incubation experiment. Leaching columns containing 50 g of soil with surface application of 100 mg per column (mg col 1) of P from each selected fertilizer and one control (nil-P) were evaluated for 60 days. Daily leachate samples from the column were analyzed for P content and pH. Soil was stratified in the end and submitted to P
fractionation. All results were analyzed considering p < 0.05. Our findings showed that TSP and struvite promoted an acid P release reaction (reaching pHs of 4.3 and 5.5 respectively), while AshDec® and hazenite reaction was alkaline (reaching pHs of 8.4 and 8.5 respectively). Furthermore, TSP promoted the highest P release among all sources in 60 days (52.8 mg col 1) and showed rapid release dynamic in the beginning, while struvite and hazenite showed late release dynamics and lower total leached P (29.7 and 15.5 mg col 1 P respectively). In contrast, no P-release was detected in the leachate of the AshDec® over the whole trial period. Struvite promoted
the highest soil labile P concentration (7938 mg kg 1), followed by hazenite (5877 mg kg 1) and AshDec® (4468 mg kg 1), all higher than TSP (3821 mg kg 1), while AshDec® showed high moderately-labile P (9214 mg kg 1), reaffirming its delayed release potential.