TY - CONF A1 - Bellon, Carsten A1 - Jaenisch, Gerd-Rüdiger A1 - Deresch, Andreas T1 - Combining analytical and Monte Carlo modelling for industrial radiology N2 - Modelling becomes more and more important in modern NDE. It is increasingly used to optimize techniques for complex applications, to support the preparation of written procedures, and for education purposes. To describe the complete chain of RT, the model includes simulating all necessary properties of X- or Gamma-ray sources, the interaction of photons with material with special attention to scattered radiation, the detection process, and the complete geometrical RT setup handling arbitrary parts or constructions. Depending on the given inspection problem and the influencing factors that should be addressed by the simulation, an appropriate physical model has to be chosen to describe the underlying interaction mechanisms. The simulator aRTist combines analytical and Monte Carlo methods to efficiently model the radiation transport such that transmission as well as scatter techniques can be modelled. In this contribution we Focus on Monte Carlo Simulation of scatter contribution within aRTist. Examples for RT/tomographic applications and back-scatter techniques are presented to demonstrate the usability of the presented simulation tool for a broad range of radiological applications. T2 - 19th Wolrd Conference on Nondestructive Testing CY - Munich, Germany DA - 13.06.2016 KW - Radiography KW - Computed tomography KW - Simulation KW - Monte Carlo methods PY - 2016 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-365856 SN - 978-3-940283-78-8 VL - 158 SP - 1 EP - 9 PB - Deutsche Gesellschaft für zerstörungsfreie Prüfung (DGZfP) CY - Berlin, Germany AN - OPUS4-36585 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Petrat, T. A1 - Graf, B. A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael ED - Schmidt, M. ED - Vollertsen, F. ED - Arnold, C. B. T1 - Laser metal deposition as repair technology for a gas turbine burner made of Inconel 718 N2 - Maintenance, repair and overhaul of components are of increasing interest for parts of high complexity and expensive manufacturing costs. In this paper a production process for laser metal deposition is presented, and used to repair a gas turbine burner of Inconel 718. Different parameters for defined track geometries were determined to attain a near net shape deposition with consistent build-up rate for changing wall thicknesses over the manufacturing process. Spot diameter, powder feed rate, welding velocity and laser power were changed as main parameters for a different track size. An optimal overlap rate for a constant layer height was used to calculate the best track size for a fitting layer width similar to the part dimension. Deviations in width and height over the whole build-up process were detected and customized build-up strategies for the 3D sequences were designed. The results show the possibility of a near net shape repair by using different track geometries with laser metal deposition. T2 - LANE - 9 International Conference on Photonic Technologies CY - Fürth, Germany DA - 19.09.2016 KW - Laser metal deposition KW - Inconel 718 KW - Additive manufacturing KW - Maintenance KW - Repair and overhaul PY - 2016 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-376723 UR - http://ac.els-cdn.com/S1875389216301857/1-s2.0-S1875389216301857-main.pdf?_tid=ed1d75de-84a2-11e6-af94-00000aab0f6c&acdnat=1474974777_4917d753cb3d316c4b000ba0760778b5 DO - https://doi.org/10.1016/j.phpro.2016.08.078 SN - 1875-3892 VL - 83 SP - 761 EP - 768 PB - Elservier AN - OPUS4-37672 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Neukammer, J. A1 - Hussels, M. A1 - Kummrow, A. A1 - Devonshire, A. A1 - Foy, C. A1 - Huggett, J. A1 - Parkes, H. A1 - Zel, J. A1 - Milavec, M. A1 - Schimmel, H. A1 - Unger, Wolfgang A1 - Akgoz, M. A1 - McHugh, V. A1 - Grunert, H.-P. A1 - Zeichhardt, H. T1 - Survey results on nucleic acid tests of infectious diseases: present status and need for rapid and patient near diagnostics N2 - This survey will discuss current and emerging isothermal and rapid polymerase chain reaction (PCR) based nucleic acid amplification methods for patient near diagnostics. To assess the clinical need of rapid diagnostics for infectious diseases based on nucleic acid tests (NATs) we performed and analysed a questionnaire among laboratories participating in corresponding INSTAND ring trials for external quality assurance. The questions concerning new amplification technologies like isothermal nucleic acid amplification, potentially suited to significantly decrease turnaround times, were complemented by questions to evaluate the present status of NATs. Besides end-users, companies were also addressed by sending out a manufacturer specific questionnaire. Analysis of the answers from 48 laboratories in 14 European countries revealed that a much shorter turnaround time is requested for selected pathogens compared to about 2 h or longer when applying temperature cycling amplification, i.e. PCR. In this context, most frequently mentioned were MRSA, norovirus, influenza A and B viruses, cytomegalovirus (CMV) as well as hepatitis B virus (HBV) and hepatitis C virus (HCV). At present, 8% of the laboratories having participated in this survey apply isothermal amplification of nucleic acid to identify infectious pathogens. KW - Nucleic acid tests KW - Infectious diseases KW - Virus detection KW - Bacteria detection KW - Isothermal nucleic acid amplification KW - Status report KW - Questionnaire KW - NAT KW - PCR PY - 2014 UR - https://nbn-resolving.org/urn:nbn:de:0183-lab0000160 UR - http://www.egms.de/static/en/journals/lab/2015-6/lab000016.shtml DO - https://doi.org/10.3205/lab000016 SN - 1869-4241 VL - 6 SP - 1 EP - 11 PB - GMS CY - Düsseldorf AN - OPUS4-36133 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Matkovic, A. A1 - Vasic, B. A1 - Pesic, J. A1 - Prinz, J. A1 - Bald, Ilko A1 - Milosavljevic, A. R. A1 - Gajic, R. T1 - Enhanced structural stability of DNA origami nanostructures by graphene encapsulation N2 - Wedemonstrate that a single-layer graphene replicates the shape ofDNAorigami nanostructures very well. It can be employed as a protective layer for the enhancement of structural stability of DNA origami nanostructures. Using the AFM based manipulation, we show that the normal force required to damage graphene encapsulated DNA origami nanostructures is over an order of magnitude greater than for the unprotected ones. In addition, we show that graphene encapsulation offers protection to the DNA origami nanostructures against prolonged exposure to deionized water, and multiple immersions. Through these results we demonstrate that graphene encapsulated DNA origami nanostructures are strong enough to sustain various solution phase processing, lithography and transfer steps, thus extending the limits of DNA-mediated bottom-up fabrication. KW - atomic force microscopy KW - graphene KW - DNA origami nanostructures PY - 2016 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-358741 UR - http://iopscience.iop.org/article/10.1088/1367-2630/18/2/025016 DO - https://doi.org/10.1088/1367-2630/18/2/025016 SN - 1367-2630 VL - 18 SP - 025016 PB - IOP PUBLISHING LTD CY - Bristol, UK AN - OPUS4-35874 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Weller, Michael G. T1 - Quality issues of research antibodies N2 - According to several recent studies, an unexpectedly high number of landmark papers seem to be not reproducible by Independent laboratories. Nontherapeutic antibodies used for research, diagnostic, food analytical, environmental, and other purposes play a significant role in this matter. Although some papers have been published offering suggestions to improve the situation, they do not seem to be comprehensive enough to cover the full complexity of this issue. In addition, no obvious improvements could be noticed in the field as yet. This article tries to consolidate the remarkable variety of conclusions and suggested activities into a more coherent conception. It is concluded that funding agencies and journal publishers need to take first and immediate measures to resolve these problems and lead the way to a more sustainable way of bioanalytical research, on which all can rely with confidence. KW - reproducibility crisis KW - irreproducibility KW - replication KW - paper retraction KW - peer reviewimmunochemistry KW - immunoassay KW - ligand binding assay KW - monoclonal antibody KW - quality control KW - cross-reactivity KW - non-specific binding KW - selectivity PY - 2016 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-356254 DO - https://doi.org/10.4137/ACI.S31614 SN - 1177-3901 VL - 11 SP - 21 EP - 27 PB - Libertas Academica CY - Auckland, New Zealand AN - OPUS4-35625 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kopyra, J. A1 - Keller, A. A1 - Bald, Ilko T1 - On the role of fluoro-substituted nucleosides in DNA radiosensitization for tumor radiation therapy N2 - Gemcitabine (2',2'-difluorocytidine) is a well-known radiosensitizer routinely applied in concomitant chemoradiotherapy. During irradiation of biological media with high-energy radiation secondary low-energy (<10 eV) electrons are produced that can directly induce chemical bond breakage in DNA by dissociative electron attachment (DEA). Here, we investigate and compare DEA to the three molecules 2'-deoxycytidine, 2'-deoxy-5-fluorocytidine, and gemcitabine. Fluorination at specific molecular sites, i.e., nucleobase or sugar moiety, is found to control electron attachment and subsequent dissociation pathways. The presence of two fluorine atoms at the sugar ring results in more efficient electron attachment to the sugar moiety and subsequent bond cleavage. For the formation of the dehydrogenated nucleobase anion, we obtain an enhancement factor of 2.8 upon fluorination of the sugar, whereas the enhancement factor is 5.5 when the nucleobase is fluorinated. The observed fragmentation reactions suggest enhanced DNA strand breakage induced by secondary electrons when gemcitabine is incorporated into DNA. KW - Dissociative electron attachment KW - DNA radiation damage KW - Gemcitabine KW - DNA radiosensitizer KW - Tumor radiation therapy PY - 2014 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-302872 DO - https://doi.org/10.1039/c3ra46735j SN - 2046-2069 VL - 4 IS - 13 SP - 6825 EP - 6829 PB - RSC Publishing CY - London AN - OPUS4-30287 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Zheng, H. A1 - Kappatos, V. A1 - Niederleithinger, Ernst A1 - Ertel, Jens-Peter A1 - Grohmann, Maria A1 - Selcuk, C. A1 - Gan, T.-H. T1 - Defect detection in concrete pile using impulse response measurements with sine sweep excitations N2 - For pile integrity inspection, a low cost and portable shaker was used to create the sine sweep signal for pile excitation. The impulse response function, calculated by the deconvolution of pile response from the sine sweep excitation, was proposed to identify the echoes in the piles due to the pile’s impedance changes. The proposed methodology has been evaluated and validated both numerically and experimentally. Based on the results from the simulations and experiments, it was found that the impulse response measurement with sine sweep excitation could be an effective tool to detect the echoes of the pile toe and the defects in the pile. T2 - NDT-CE 2015 - International symposium non-destructive testing in civil engineering CY - Berlin, Germany DA - 15.09.2015 KW - Impulse response function KW - Sine sweep excitation KW - Pile integrity KW - Damage detection PY - 2015 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-347157 SN - 1435-4934 SP - 1 EP - 4 PB - Technische Universität Berlin / Bundesanstalt für Materialforschung und -prüfung AN - OPUS4-34715 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pretsch, Thorsten T1 - Review on the functional determinants and durability of shape memory polymers N2 - Shape memory polymers (SMP) belong to the class of stimuli-responsive materials and have generated significant research interest. Their capability to retain an imposed, temporary shape and to recover the initial, permanent shape upon exposure to an external stimulus depends on the "functional determinants", which in simplistic terms, can be divided into structural/morphological and processing/environmental factors. The primary aim of the first part of this review is to reflect the knowledge about these fundamental relationships. In a next step, recent advances in shape memory polymer composites are summarized. In contrast to earlier reviews, studies on the impairment of shape memory properties through various factors, such as aging, compression and hibernation, lubricants, UV light and thermo-mechanical cycling, are extensively reviewed. Apart from summarizing the state-of-the-art in SMP research, recent progress is commented. KW - Shape memory polymer KW - Active polymer KW - Shape memory polymer composite KW - Shape memory properties KW - Functionality KW - Degradation KW - Aging KW - Functional determinants KW - Thermo-mechanical testing KW - Durability PY - 2010 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-217390 UR - http://www.mdpi.com/2073-4360/2/3/120/pdf DO - https://doi.org/10.3390/polym2030120 SN - 2073-4360 VL - 2 IS - 3 SP - 120 EP - 158 PB - MDPI CY - Basel AN - OPUS4-21739 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Weller, Michael G. T1 - A unifying review of bioassay-guided fractionation, effect-directed analysis and related techniques N2 - The success of modern methods in analytical chemistry sometimes obscures the problem that the ever increasing amount of analytical data does not necessarily give more insight of practical relevance. As alternative approaches, toxicity- and bioactivity-based assays can deliver valuable information about biological effects of complex materials in humans, other species or even ecosystems. However, the observed effects often cannot be clearly assigned to specific chemical compounds. In these cases, the establishment of an unambiguous cause-effect relationship is not possible. Effect-directed analysis tries to interconnect instrumental analytical techniques with a biological/biochemical entity, which identifies or isolates substances of biological relevance. Successful application has been demonstrated in many fields, either as proof-of-principle studies or even for complex samples. This review discusses the different approaches, advantages and limitations and finally shows some practical examples. The broad emergence of effect-directed analytical concepts might lead to a true paradigm shift in analytical chemistry, away from ever growing lists of chemical compounds. The connection of biological effects with the identification and quantification of molecular entities leads to relevant answers to many real life questions. KW - Toxicity KW - Drug discovery KW - Natural products KW - Environmental analysis KW - Lead identification PY - 2012 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-262960 DO - https://doi.org/10.3390/s120709181 SN - 1424-8220 VL - 12 IS - 7 SP - 9181 EP - 9209 PB - MDPI CY - Basel AN - OPUS4-26296 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hernández-Nava, E. A1 - Tammas-Williams, S. A1 - Smith, C. A1 - Léonard, Fabien A1 - Withers, P. J. A1 - Todd, I. A1 - Goodall, R. T1 - X-ray tomography characterisation of lattice structures processed by selective electron beam melting N2 - Metallic lattice structures intentionally contain open porosity; however, they can also contain unwanted closed porosity within the structural members. The entrained porosity and defects within three different geometries of Ti-6Al-4V lattices, fabricated by Selective Electron Beam Melting (SEBM), is assessed from X-ray computed tomography (CT) scans. The results suggest that horizontal struts that are built upon loose powder show particularly high (~20 x 10⁻³ vol %) levels of pores, as do nodes at which many (in our case 24) struts meet. On the other hand, for struts more closely aligned (0° to 54°) to the build direction, the fraction of porosity appears to be much lower (~0.17 x 10⁻³%) arising mainly from pores contained within the original atomised powder particles. KW - Cellular solids KW - Aqdditive manufacturing KW - Computed tomography KW - Titanium alloys PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-413689 UR - http://www.mdpi.com/2075-4701/7/8/300 DO - https://doi.org/10.3390/met7080300 SN - 2075-4701 VL - 7 IS - 8 SP - Article 300, 1 EP - 12 PB - MDPI AN - OPUS4-41368 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Naresh-Kumar, G. A1 - Vilalta-Clemente, A. A1 - Jussila, H. A1 - Winkelmann, Aimo A1 - Nolze, Gert A1 - Vespucci, S. A1 - Nagarajan, S. A1 - Wilkinson, A. J. A1 - Trager-Cowan, C. T1 - Quantitative imaging of anti-phase domains by polarity sensitive orientation mapping using electron backscatter diffraction N2 - Advanced structural characterisation techniques which are rapid to use, non-destructive and structurally definitive on the nanoscale are in demand, especially for a detailed understanding of extended-defects and their influence on the properties of materials. We have applied the electron backscatter diffraction (EBSD) technique in a scanning electron microscope to non-destructively characterise and quantify antiphase domains (APDs) in GaP thin films grown on different (001)Si substrates with different offcuts. We were able to image and quantify APDs by relating the asymmetrical intensity distributions observed in the EBSD patterns acquired experimentally and comparing the same with the dynamical electron diffraction simulations. Additionally mean angular error maps were also plotted using automated cross-correlation based approaches to image APDs. Samples grown on substrates with a 4° offcut from the [110] do not show any APDs, whereas samples grown on the exactly oriented substrates contain APDs. The procedures described in our work can be adopted for characterising a wide range of other material systems possessing non-centrosymmetric point groups. KW - Polarity KW - Semiconductor KW - Antiphase boundary PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-420167 SN - 2045-2322 VL - 7 SP - Article 10916, 1 EP - 10 AN - OPUS4-42016 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lai Wai-Lok, Wallace A1 - Kind, Thomas A1 - Wiggenhauser, Herbert T1 - A study of concrete hydration and dielectric relaxation mechanism using ground penetrating radar and short-time fourier transform N2 - Ground penetrating radar (GPR) was used to characterize the frequency-dependent dielectric relaxation phenomena in ordinary Portland cement (OPC) hydration in concrete changing from fresh to hardened state. The study was experimented by measuring the changes of GPR A-scan waveforms over a period of 90 days, and processed the waveforms with short-time Fourier transform (STFT) in joint time-frequency analysis (JTFA) domain rather than a conventional time or frequency domain alone. The signals of the direct wave traveled at the concrete surface and the reflected wave from an embedded steel bar were transformed with STFT, in which the changes of peak frequency over ages were tracked. The peak frequencies were found to increase with ages and the patterns were found to match closely with primarily the well-known OPC hydration process and secondarily, the evaporation effect. The close match is contributed to the simultaneous effects converting free to bound water over time, on both conventional OPC hydration and dielectric relaxation mechanisms. KW - Soil water content KW - Wet soil KW - Microwave KW - Moisture KW - GPR KW - Dispersion PY - 2010 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-239723 DO - https://doi.org/10.1155/2010/317216 SN - 1687-6172 IS - Article ID 317216 SP - 1 EP - 14 PB - Hindawi Publ. CY - New York, NY, USA AN - OPUS4-23972 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Shokouhi, Parisa A1 - Zoëga, Andreas A1 - Wiggenhauser, Herbert T1 - Nondestructive investigation of stress-induced damage in concrete N2 - The changes in the sonic surface wave velocity of concrete under stress were investigated in this paper. Surface wave velocities at sonic frequency range were measured on a prismatic concrete specimen undergoing several cycles of uniaxial compression. The loading was applied (or removed) gradually in predefined small steps (stress-controlled). The surface wave velocity was measured at every load step during both loading and unloading phases. Acoustic Emission (AE) test was conducted simultaneously to monitor the microcracking activities at different levels of loading. It was found that the sonic surface wave velocity is highly stress dependent and the velocity-stress relationship follows a particular trend. The observed trend could be explained by a combination of acoustoelasticity and microcracking theories, each valid over a certain range of applied stresses. Having measured the velocities while unloading, when the material suffers no further damage, the effect of stress and damage could be differentiated. The slope of the velocity-stress curves over the elastic region was calculated for different load cycles. This quantity was normalized to yield a dimensionless nonlinear parameter. This parameter generally increases with the level of induced damage in concrete. KW - Nondestructive testing (NDT) KW - Surface wave velocity KW - Concrete KW - Acoustoelasticity KW - Microcracking PY - 2010 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-215943 UR - http://downloads.hindawi.com/journals/ace/2010/740189.pdf DO - https://doi.org/10.1155/2010/740189 SN - 1687-8094 SN - 1687-8086 VL - 2010 IS - Article ID 740189 SP - 1 EP - 9 PB - Hindawi Publ. Corp. CY - New York, NY, USA AN - OPUS4-21594 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Cervino, C. A1 - Knopp, D. A1 - Weller, Michael G. A1 - Niessner, R. T1 - Novel Aflatoxin derivatives and protein conjugates N2 - Aflatoxins, a group of structurally related mycotoxins, are well known for their toxic and carcinogenic effects in humans and animals. Aflatoxin derivatives and protein conjugates are needed for diverse analytical applications. This work describes a reliable and fast synthesis of novel aflatoxin derivatives, purification by preparative HPLC and characterisation by ESI-MS and one- and two-dimensional NMR. Novel aflatoxin bovine serum albumin conjugates were prepared and characterised by UV absorption and MALDI-MS. These aflatoxin protein conjugates are potentially interesting as immunogens for the generation of aflatoxin selective antibodies with novel specificities. KW - Aflatoxin KW - Mycotoxin KW - Hapten KW - Protein conjugation KW - Immunogen KW - Antigen KW - Antibody PY - 2007 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-147572 UR - http://www.mdpi.org/molecules/papers/12030641.pdf UR - http://www.mdpi.org/molecules/papers/12030641sm.pdf DO - https://doi.org/10.3390/12030641 SN - 1420-3049 VL - 12 IS - 3 SP - 641 EP - 653 PB - MDPI CY - Basel AN - OPUS4-14757 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Moreira, E.V. A1 - Rabello, J.M.B. A1 - Pereira, M.d.S. A1 - Lopes, R.T. A1 - Zscherpel, Uwe T1 - Digital radiography using digital detector arrays fulfills critical applications for offshore pipelines N2 - Digital radiography in the inspection of welded pipes to be installed under deep water offshore gas and oil pipelines, like a presalt in Brazil, in the paper has been investigated. The aim is to use digital radiography for nondestructive testing of welds as it is already in use in the medical, aerospace, security, automotive, and petrochemical sectors. Among the current options, the DDA (Digital Detector Array) is considered as one of the best solutions to replace industrial films, as well as to increase the sensitivity to reduce the inspection cycle time. This paper shows the results of this new technique, comparing it to radiography with industrial films systems. In this paper, 20 test specimens of longitudinal welded pipe joints, specially prepared with artificial defects like cracks, lack of fusion, lack of penetration, and porosities and slag inclusions with varying dimensions and in 06 different base metal wall thicknesses, were tested and a comparison of the techniques was made. These experiments verified the purposed rules for parameter definitions and selections to control the required digital radiographic image quality as described in the draft international standard ISO/DIS 10893-7. This draft is first standard establishing the parameters for digital radiography on weld seam of welded steel pipes for pressure purposes to be used on gas and oil pipelines. KW - Zerstörungsfreie Prüfung von Schweißnähten KW - Durchstrahlungsprüfung KW - Digitale Radiologie PY - 2010 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-225319 DO - https://doi.org/10.1155/2010/894643 SN - 1687-6172 VL - 2010 IS - Article ID 894643 SP - 1 EP - 7 PB - Hindawi Publ. CY - New York, NY, USA AN - OPUS4-22531 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Guitton-Spassky, Tiffany A1 - Schade, Boris A1 - Zoister, Christian A1 - Veronese, Eleonora A1 - Rosati, Marta A1 - Baldelli Bombelli, Francesca A1 - Cavallo, Gabriella A1 - Thünemann, Andreas A1 - Ghermezcheshme, Hassan A1 - Makki, Hesam A1 - Netz, Roland R. A1 - Ludwig, Kai A1 - Metrangolo, Pierangelo A1 - Singh, Abhishek Kumar A1 - Haag, Rainer T1 - Fluorinated Hexosome Carriers for Enhanced Solubility of Drugs N2 - Designing nanomaterials for drug encapsulation is a crucial, yet challenging, aspect for pharmaceutical development. An important step is synthesizing amphiphiles that form stable supramolecular systems for efficient drug loading. In the case of fluorinated drugs, these have superior properties and also a tendency toward reduced water solubility. For the first time, we report here fluorinated hexosome carriers made from nonionic dendritic amphiphiles, capable of encapsulating the fluorinated drug Leflunomide with high efficiency (62 ± 3%) and increasing its solubility by 12-fold. We synthesized amphiphiles with varying tail groups (fluorinated/alkylated), and their supramolecular self-assembly was investigated using cryogenic transmission electron microscopy and small-angle X-ray scattering. Furthermore, Leflunomide and its equivalent nonfluorinated counterpart were encapsulated within fluorinated and nonfluorinated assemblies. Self-assembly and encapsulation mechanisms were well supported by coarse-grained molecular simulations, yielding a fundamental understanding of the new systems. KW - PEFAS KW - Small-angle X-ray scattering KW - SAXS KW - Reference method PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-632002 DO - https://doi.org/10.1021/jacsau.5c00198 SN - 2691-3704 VL - 5 IS - 5 SP - 2223 EP - 2236 PB - American Chemical Society (ACS) CY - Washington, DC AN - OPUS4-63200 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zhang, Qiang A1 - Heuchel, Matthias A1 - Thünemann, Andreas A1 - Machatscheck, Rainhard T1 - The role of diffusion in the hydrolytic degradation of poly(lactic-co-glycolic acid): A molecular perspective N2 - This research emphasizes the importance of internal surface erosion as a key factor in the hydrolytic degradation of PLGA (poly(D,L-lactic-co-glycolic acid)) providing an alternative view of the established surface and bulk erosion degradation modes. Using molecular dynamics (MD) simulations, this study reveals the role of water and oligomer diffusion during the degradation of PLGA and highlights the importance of water channels formed as the overall water content increases. We found that these continuous water channels play a crucial role in accelerating the transport of water and the release of degradation products from the polymer matrix, as the diffusion coefficients of water and small oligomers exhibit significant differences spanning 2 to 3 orders of magnitude between the water and polymer phases. Water follows a different diffusion mechanism than polymer fragments. The diffusion rate of the fragments up to a size of octamers was found to be size-dependent and reasonably well approximated by a 1/N behavior, in line with the Rouse model. KW - Small-angle X-ray scattering KW - SAXS KW - Nanostructure KW - PLGA PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-621250 DO - https://doi.org/10.1016/j.polymdegradstab.2024.111119 VL - 232 SP - 1 EP - 12 PB - Elsevier Ltd. AN - OPUS4-62125 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lange, Alyna A1 - Holtzheimer, Lea A1 - Clarke, Coby A1 - Thünemann, Andreas A1 - Taubert, Andreas T1 - Complex Self-Organization in n-Alkylammonium Sulfobetaine Zwitterions with High Thermal Stabilities and High Expansion Coefficients N2 - Sulfobetaine zwitterions made from n-alkyl dimethylamines and butanesultone yield a series of n-alkylammonium sulfobetaine zwitterions with complex self-organization behavior. The compounds are thermally quite stable and the length of the alkyl chain directly affects all phase transition temperatures of the compounds: the longer the alkyl chain, the higher the transition temperature. All compounds exhibit lamellar order and the different phases are characterized by a lower temperature orthorhombic and a higher temperature hexagonal in-plane order. The phase transition from the orthorhombic to the hexagonal phase is always associated with an increase of the long period. The phase transition is also associated with a rather high thermal expansion coefficient. KW - SAXS KW - Small-angle X-ray scattering KW - Nanostructure PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-626276 DO - https://doi.org/10.1021/acs.langmuir.4c02892 SN - 1520-5827 VL - 41 SP - 4422 EP - 4434 PB - American Chemical Society (ACS) AN - OPUS4-62627 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kieserling, Helena A1 - Sieg, Holger A1 - Heilscher, Jasmin A1 - Drusch, Stephan A1 - Braeuning, Albert A1 - Thünemann, Andreas A1 - Rohn, Sascha T1 - Towards Understanding Particle-Protein Complexes: Physicochemical, Structural, and Cellbiological Characterization of β-Lactoglobulin Interactions with Silica, Polylactic Acid, and Polyethylene Terephthalate Nanoparticles N2 - Nanoplastic particles and their additives are increasingly present in the food chain, interacting with biomacromolecules with not yet known consequences. A protein corona forms around the particles in these usually complex matrices, primarily with a first contact at surface-active proteins. However, systematic studies on the interactions between the particles and proteins –especially regarding protein affinity and structural changes due to surface properties like polarity – are limited. It is also unclear whether the protein corona can "mask" the particles, mimic protein properties, and induce cytotoxic effects when internalized by mammalian cells. This study aimed at investigating the physicochemical properties of model particle-protein complexes, the structural changes of adsorbed proteins, and their effects on Caco-2 cells. Whey protein β-lactoglobulin (β-Lg) was used as a well-characterized model protein and studied in a mixture with nanoparticles of varying polarity, specifically silica, polylactic acid (PLA), and polyethylene terephthalate (PET). The physicochemical analyses included measurements of the hydrodynamic diameter and the zeta potential, while the protein conformational changes were analyzed using Fourier-transform-infrared spectroscopy (FTIR) and intrinsic fluorescence. Cellular uptake in Caco-2 cells was assessed through flow cytometry, cell viability was measured using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium-bromide (MTT) assay, and cellular impedance was analyzed with xCELLigence® technology. The results indicated that β-Lg had the highest affinity for hydrophilic silica particles, forming silica-β-Lg complexes and large aggregates through electrostatic interactions. The affinity decreased for PLA and was lowest for hydrophobic PET, which formed smaller complexes. Adsorption onto silica caused partial unfolding and refolding of β-Lg. The silica-β-Lg complexes were internalized by Caco-2 cells, impairing cell proliferation. In contrast, PLA- and PET-protein complexes were not internalized, though PLA complexes slightly reduced cell viability. This study enhances our understanding of protein adsorption on nanoparticles and its potential biological effects. KW - Nanoplastics KW - Microplastics KW - Reference materials KW - Scattering KW - DLS PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-630093 DO - https://doi.org/10.1016/j.colsurfb.2025.114702 SN - 1873-4367 VL - 253 SP - 1 EP - 12 PB - Elsevier BV CY - Amsterdam AN - OPUS4-63009 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mikhlin, Yuri A1 - Muzikansky, Anya A1 - Zysler, Melina A1 - Thünemann, Andreas A1 - Zitoun, David T1 - Emerging electrochemistry of high-concentration colloids: Redox-activity, wide potential window and electrophoretic transport of iron oxide nanoparticles N2 - High-concentration, steric stabilizer free colloids and particularly their electrochemical behavior remains almost unexplored. Herein, we report on the electrochemistry (cyclic voltammetry, impedance spectroscopy, etc.) of highly concentrated aqueous colloidal dispersion up to 800 g/L of citrate-capped ∼11 nm Fe3-xO4 nanoparticles (NPs) without background electrolyte on glassy carbon electrodes. X-ray photoelectron spectroscopy was applied to analyze the reaction products. Solid-state Fe(II)/Fe(III) conversion was concluded to determine the cathodic and anodic faradaic reactions of the particles, with the currents depending on approximately square root of the concentration. The electrochemical reactions are coupled with the electrophoretic transfer of the negatively charged NPs on toward the anode, with the ohmic-type behavior in the bulk demonstrated by the nearly linear voltametric cathodic curves and frequency-independent impedance above ∼10–100 Hz. Accumulation and clogging of the NPs retards diffusion near anode. Hydrogen and especially oxygen evolution are arrested, and very large oxidation overpotentials result in extraordinary wide, up to 12 V, electrochemical window of water stability. The findings shed light onto basic features of the electrochemistry of high-concentration colloids without added electrolyte and their potential applications in redox flow batteries, electrophoretic deposition and beyond. KW - Nanoplastics KW - SAXS KW - Small-angle X-ray scattering PY - 2026 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-644340 DO - https://doi.org/10.1016/j.jcis.2025.139247 SN - 0021-9797 VL - 703 SP - 1 EP - 18 PB - Elsevier Inc. AN - OPUS4-64434 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -