TY - CONF A1 - Hahn, Marc Benjamin A1 - Solomun, Tihomir A1 - Sturm, Heinz T1 - A standard procedure for the irradiation of biomolecules with radiation of varying linear energy transfer N2 - The damage caused by ionizing radiation to DNA and proteins is the reason to treat cancer by radiation therapy. A better understanding of the molecular processes and quantification of the different damaging mechanisms is the prerequisite to develop more efficient therapies. Hereby the understanding of the processes involved in the damage to DNA are of key interest due to its central role in reproduction and mutation. For radiation with low linear energy transfer (LET), most of the damage is caused by the secondary particles produced by scattering of the ionizing radiation with water. Thereby a multitude of species are produced, whereby especially kinetic low energy electrons, prehydrated electrons, OH-radicals and ions are of importance. With higher LET the relative amount of the direct damaging effects increases. This is especially important considering the increased usage of high LET nucleons in radiation therapy. Therefore, the quantification of the contribution to DNA damage of direct and indirect effects and the different secondary species is of high interest due to the increase of radio biological efficiency when applying high LET radiation. Here we present an approach to investigate the relative contributions to DNA strand break yield for radiation of different LET within a single electron microscope in combination with electron scattering simulations. T2 - IRPA 2018 CY - Havanna, Cuba DA - 16.04.2018 KW - Dosimetry KW - Microdosimetry KW - LET KW - SEM KW - DNA KW - Radiation damage KW - OH radicals KW - LEE KW - Ionizing radiation KW - Geant4 PY - 2018 AN - OPUS4-44820 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Neamtu, Mariana A1 - Nadejde, C. A1 - Hodoroaba, Vasile-Dan A1 - Schneider, Rudolf A1 - Verestiuc, L. A1 - Panne, Ulrich T1 - Functionalized magnetic nanoparticles: Synthesis, characterization, catalytic application and assessment of toxicity N2 - Cost-effective water cleaning approaches using improved Treatment technologies, for instance based on catalytic processes with high activity catalysts, are urgently needed. The aim of our study was to synthesize efficient Fenton-like photo-catalysts for rapid degradation of persistent organic micropollutants in aqueous medium. Iron-based nanomaterials were chemically synthesized through simple procedures by immobilization of either iron(II) oxalate (FeO) or iron(III) citrate (FeC) on magnetite (M) nanoparticles stabilized with polyethylene glycol (PEG). Various investigation techniques were performed in order to characterize the freshly prepared catalysts. By applying advanced oxidation processes, the effect of catalyst dosage, hydrogen peroxide concentration and UV-A light exposure were examined for Bisphenol A (BPA) conversion, at laboratory scale, in mild conditions. The obtained results revealed that BPA degradation was rapidly enhanced in the presence of low-concentration H2O2, as well as under UV-A light, and is highly dependent on the surface characteristics of the catalyst. Complete photo-degradation of BPA was achieved over the M/PEG/FeO catalyst in less than 15 minutes. Based on the catalytic performance, a hierarchy of the tested catalysts was established: M/PEG/FeO > M/PEG/FeC > M/PEG. The results of cytotoxicity assay using MCF-7 cells indicated that the aqueous samples after treatment are less cytotoxic. KW - Bisphenol A KW - Magnetic nanocatalyst KW - Endocrine disruptor KW - Nanoparticle KW - Photodegradation KW - Fenton PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-448297 DO - https://doi.org/10.1038/s41598-018-24721-4 SN - 2045-2322 VL - 8 SP - Article 6278, 1 EP - 11 PB - Springer Nature CY - London AN - OPUS4-44829 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mekonnen, Tessema Fenta A1 - Panne, Ulrich A1 - Koch, Matthias T1 - New photodegradation products of the fungicide fluopyram: Structural elucidation and mechanism identification N2 - Identifying the fate of agrochemicals is important to understand their potential risk for living organisms. We report here new photodegradation products (PPs) of the fungicide fluopyram. The PPs were produced by irradiating a fluopyram standard in 0.1% acetonitrile aqueous media by a 150-W medium pressure Hg-lamp that emits wavelengths between 200–280 nm. The structural elucidation of PPs was achieved by combining the retention time, isotopic pattern, targeted fragmentation, and accurate mass measurements using liquid chromatography-tandem mass spectrometry (LC-MS/MS) and high resolution-MS (HRMS). In addition to previously known PPs, seven new PPs of fluopyram were identified in this work: mainly dihydroxyl and hydroxylimide fluopyram as well as mono, di, and trihydroxyl lactam. Additionally, two PPs were found to be formed by rearrangement after the loss of H2C=CH2. Hence, the results of the work contribute to extending the current knowledge regarding the photoinduced fate of agrochemicals, and fluopyram in particular. KW - Photodegradation KW - Transformation products KW - LC-MS/MS KW - HRMS KW - Fungicide PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-466347 DO - https://doi.org/10.3390/molecules23112940 SN - 1420-3049 VL - 23 IS - 11 SP - 2940, 1 EP - 13 PB - MDPI CY - Basel AN - OPUS4-46634 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Crasselt, Claudia A1 - Schmidt, Wolfram A1 - Sturm, Heinz T1 - Influence of Rheology Modifying Admixtures on Hydration of Cementitious Suspensions N2 - The presence of polycarboxylate ether (PCE) based superplasticizers (SPs) has an enormous influence on the early hydration of cement. The hydration is retarded and the timing of formation and the morphology of hydrates is affected. This short paper presents experimental results about the influence of delayed addition time of PCE SPs on hydration of cement and alite pastes, investigated by isothermal heat flow calorimetry. For cement as well as for alite pastes the hydration is retarded with SP, whereby the high charge PCE has a stronger retarding effect than the low charge PCE. The retardation caused by PCE is much more pronounced for alite than for cement mixes. If PCE is added later to the mix, the induction period is shortened and the hydration is accelerated compared to simultaneous addition. This applies for cement and alite pastes. With delayed PCE addition the alite shows a clearly less retarded setting and main hydration than after simultaneous addition. It is obvious that for alite pastes there is less retardation the later the addition of SP. T2 - 6th International Symposium on Nanotechnology in Construction CY - Hong Kong, China DA - 02.12.2018 KW - Polycarboxylate ether (PCE) KW - Early hydration KW - Cement PY - 2018 SP - 1 EP - 8 AN - OPUS4-47204 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Weigert, Florian A1 - Müller, A. A1 - Häusler, I. A1 - Geißler, Daniel A1 - Skroblin, D. A1 - Unger, Wolfgang A1 - Radnik, Jörg A1 - Resch-Genger, Ute T1 - Combining HR‑TEM and XPS to elucidate the core–shell structure of ultrabright CdSe/CdS semiconductor quantum dots N2 - Controlling thickness and tightness of surface passivation shells is crucial for many applications of core–shell nanoparticles (NP). Usually, to determine shell thickness, core and core/shell particle are measured individually requiring the availability of both nanoobjects. This is often not fulfilled for functional nanomaterials such as many photoluminescent semiconductor quantum dots (QD) used for bioimaging, solid state lighting, and display technologies as the core does not show the applicationrelevant functionality like a high photoluminescence (PL) quantum yield, calling for a whole nanoobject approach. By combining high-resolution transmission electron microscopy (HR-TEM) and X-ray photoelectron spectroscopy (XPS), a novel whole nanoobject approach is developed representatively for an ultrabright oleic acid-stabilized, thick shell CdSe/CdS QD with a PL quantum yield close to unity. The size of this spectroscopically assessed QD, is in the range of the information depth of usual laboratory XPS. Information on particle size and monodispersity were validated with dynamic light scattering (DLS) and small angle X-ray scattering (SAXS) and compared to data derived from optical measurements. In addition to demonstrating the potential of this novel whole nanoobject approach for determining architectures of small nanoparticles, the presented results also highlight challenges faced by different sizing and structural analysis methods and method-inherent uncertainties. KW - Photoluminescence KW - Single particle KW - Microscopy KW - Particle architecture KW - Thickness KW - SAXS KW - Shell KW - XPS KW - TEM KW - Semiconductor KW - Quantum dot KW - Photophysics KW - Quantum yield PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-517911 DO - https://doi.org/10.1038/s41598-020-77530-z VL - 10 IS - 1 SP - 20712 PB - Springer Nature AN - OPUS4-51791 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Broicher, Cornelia A1 - Zeng, F. A1 - Pfänder, N. A1 - Frisch, M. A1 - Bisswanger, T. A1 - Radnik, Jörg A1 - Stockmann, Jörg M. A1 - Palkovits, S. A1 - Beine, A. K. A1 - Palkovits, R. T1 - Iron and Manganese Containing Multi-Walled Carbon Nanotubes as Electrocatalysts for the Oxygen Evolution Reaction - Unravelling Influences on Activity and Stability N2 - Hydrogen economy is a central aspect of future energy supply, as hydrogen can be used as energy storage and fuel. In order tomake water electrolysis efficient, the limiting oxygen evolution reaction (OER) needs to be optimized. Therefore, C-based composite materials containing earth-abundant Fe and Mn were synthesized, characterized and tested in the OER. For pyrolysis temperatures above 700°C N-rich multi-walled carbon nanotubes (MWCNT) are obtained. Inside the tubes Fe3C particles are formed, Fe and Mn oxides are incorporated in the carbon matrix and metal spinel nanoparticles cover the outer surface. The best catalyst prepared at 800°C achieves a low overpotential of 389 mV (at 10 mA/cm2) and high stability (22.6 h). From electrochemical measurements and characterization it can be concluded that the high activity is mainly provided by MWCNT, Fe3C and the metal oxides in the conductive carbon matrix. The metal spinel nanoparticles in contrast protect the MWCNT from oxidation and thereby contribute to the high stability. KW - Oxygen Evolution Reaction KW - Carbon Nanotubes KW - Stability PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-513955 DO - https://doi.org/10.1002/cctc.202000944 VL - 12 IS - 21 SP - 1 EP - 8 PB - Wiley Online Libary AN - OPUS4-51395 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Solomun, Tihomir A1 - Hahn, Marc Benjamin A1 - Smiatek, J. T1 - Raman spectroscopic signature of ectoine conformations in bulk solution and crystalline state N2 - Recent crystallographic results revealed conformational changes of zwitterionic ectoine upon hydration. By means of confocal Raman spectroscopy and density functional theory calculations, we present a detailed study of this transformation process as part of a Fermi resonance analysis. The corresponding findings highlight that all resonant couplings are lifted upon exposure to water vapor as a consequence of molecular binding processes. The importance of the involved molecular groups for water binding and conformational changes upon hydration is discussed. Our approach further Shows that the underlying rapid process can be reversed by carbon dioxide saturated atmospheres. For the first time, we also confirm that the conformational state of ectoine in aqueous bulk solution coincides with crystalline ectoine in its dihydrate state, thereby highlighting the important role of a few bound water molecules. KW - Fermi resonance KW - Ectoine hydration KW - DFT calculations of Raman spectra KW - Position of carboxylate group PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-509855 DO - https://doi.org/10.1002/cphc.202000457 SN - 1439-4235 SN - 1439-7641 VL - 21 IS - 17 SP - 1945 EP - 1950 PB - Wiley-VCH CY - Weinheim AN - OPUS4-50985 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hünger, K.-J. A1 - Kositz, M. A1 - Danneberg, M. A1 - Radnik, Jörg T1 - Enrichment of aluminium in the near‐surface region of natural quartzite rock after aluminium exposure N2 - Alkali–silica reaction (ASR) is an ongoing problem that causes damage to concrete constructions and reduces their durability. Therefore, minimizing this undesired reaction is of great interest for both safety and economic reasons. Additives containing high aluminium content are very effective in reducing the release of silica and enhancing the durability of concrete; however, the mechanism for this effect is still under discussion. In this study, an enrichment of aluminium in the near‐surface region was observed for natural quartzite rock after storage in Al (OH)3 and metakaolin as aluminium sources, from which we conclude that the formation of aluminosilicate sheets of a few nanometres inhibits the silica release; this hypothesis is supported by high‐resolution spectra of Al 2p, Si 2p and O 1s. KW - Alkali-silica reaction KW - Quartzite rock KW - X-ray photoelectron spectroscopy PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-519394 DO - https://doi.org/10.1002/sia.6918 SN - 0142-2421 SP - 1 EP - 7 PB - Wiley VCH AN - OPUS4-51939 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Dudziak, Mateusz A1 - Topolniak, Ievgeniia A1 - Silbernagl, Dorothee A1 - Altmann, Korinna A1 - Sturm, Heinz T1 - Long-time behavior of surface properties of microstructures fabricated by multiphoton lithography N2 - The multiphoton lithography (MPL) technique represents the future of 3D microprinting, enabling the production of complex microscale objects with high precision. Although the MPL fabrication parameters are widely evaluated and discussed, not much attention has been given to the microscopic properties of 3D objects with respect to their surface properties and time-dependent stability. These properties are of crucial importance when it comes to the safe and durable use of these structures in biomedical applications. In this work, we investigate the surface properties of the MPL-produced SZ2080 polymeric microstructures with regard to the physical aging processes during the post-production stage. The influence of aging on the polymeric microstructures was investigated by means of Atomic Force Microscopy (AFM) and X-ray Photoelectron Spectroscopy (XPS). As a result, a time-dependent change in Young’s Modulus, plastic deformation, and adhesion and their correlation to the development in chemical composition of the surface of MPL-microstructures are evaluated. The results presented here are valuable for the application of MPL-fabricated 3D objects in general, but especially in medical technology as they give detailed information of the physical and chemical time-dependent dynamic behavior of MPL-printed surfaces and thus their suitability and performance in biological systems. KW - Multiphoton lithography KW - Additive manufacturing KW - Microfabrication KW - SZ2080 negative photo-resist KW - Young´s modulus KW - Aging KW - Surface properties KW - X-ray photoelectron spectroscopy KW - Atomic force microscopy KW - Force-distance-curve PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-542166 DO - https://doi.org/10.3390/nano11123285 SN - 2079-4991 VL - 11 IS - 12 SP - 1 EP - 12 PB - MDPI CY - Basel AN - OPUS4-54216 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Donskyi, Ievgen A1 - Nie, C. A1 - Ludwig, K. A1 - Trimpert, J. A1 - Ahmed, R. A1 - Quaas, E. A1 - Achazi, K. A1 - Radnik, Jörg A1 - Adeli, M. A1 - Haag, R. A1 - Osterrieder, K. T1 - Graphene Sheets with Defined Dual Functionalities for the Strong SARS-CoV-2 Interactions N2 - Search of new strategies for the inhibition of respiratory viruses is one of the urgent health challenges worldwide, as most of the current therapeutic agents and treatments are inefficient. Severe acute respiratory syndrome coronavirus 2 (SARSCoV-2) has caused a pandemic and has taken lives of approximately two Million people to date. Even though various vaccines are currently under development, virus, and especially its spike glycoprotein can mutate, which highlights a Need for a broad-spectrum inhibitor. In this work, inhibition of SARS-CoV-2 by graphene platforms with precise dual sulfate/alkyl functionalities is investigated. A series of graphene derivatives with different lengths of aliphatic chains is synthesized and is investigated for their ability to inhibit SARS-CoV-2 and feline coronavirus. Graphene derivatives with long alkyl chains (>C9) inhibit coronavirus replication by virtue of disrupting viral envelope. The ability of these graphene platforms to rupture viruses is visualized by atomic force microscopy and cryogenic electron microscopy. A large concentration window (10 to 100-fold) where graphene platforms display strongly antiviral activity against native SARS-CoV-2 without significant toxicity against human cells is found. In this concentration range, the synthesized graphene platforms inhibit the infection of enveloped viruses efficiently, opening new therapeutic and metaphylactic avenues against SARS-CoV-2. KW - Graphene KW - Graphene-based polyglycerol sulfates KW - SARS-CoV2 inhibitor KW - Virucidality PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-520858 DO - https://doi.org/10.1002/smll.202007091 VL - 17 IS - 11 SP - 7091 PB - Wiley VCH AN - OPUS4-52085 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -