TY - CONF A1 - Musyanovych, A. A1 - Grimmer, Christoph A1 - Sadak, A. E. A1 - Heßling, L. A1 - Bilsel, M. A1 - Horn, Wolfgang A1 - Richter, Matthias T1 - Polymeric Capsules with VOCs for Controlled Emission N2 - Micro-(nano-)encapsulation technology involves building of a barrier between the core and the environment and offers a number of benefits to preserve the functional and physicochemical properties of core material. Tremendous progress has been made in synthesizing well-defined capsules to achieve desired properties such as particle size, chemical composition, and controlled release of the payload. Encapsulation of volatile organic compounds (VOCs) that could evaporate with a defined rate is of immense interest for application in emission reference materials (ERM). These are urgently needed for quality assurance and quality control purposes (QA/QC) required by test standards for the determination of chemical emissions of construction and other materials for interior use. As such ERMs are hardly available on the market, the EU-funded EMPIR project MetrIAQ [1] was started to fill this gap by developing a material with temporally constant emission of VOCs typically found in indoor air. Different capsules in a size range between 5 and 50 μm were synthesized through an interfacial polyaddition/polycondensation reaction in direct (water-in-oil) system. As VOC several types of hydrophobic liquid materials were used. After synthesis, the morphology and physicochemical properties of capsules were characterized by electron microscopy, FTIR and DSC/TGA. An encapsulation efficiency up to 90% could be reached. The emission kinetic of volatile agents was studied in emission test chambers at 23 °C and 50% RH for 14 days. First results indicate that variation of the cross-linking grade of the shell material is one important parameter to adjust the desired emission rate. The overall aim is to achieve a consistent emission profile that decreases by less than 10 % over a target period of at least 14 days. T2 - 36th European Colloid & Interface Society Conference CY - Chania, Crete, Greece DA - 04.09.2022 KW - Capsules KW - Volatile organic compound KW - Polymer KW - Material emissions KW - Reference materials PY - 2022 AN - OPUS4-56039 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Musyanovych, A. A1 - Grimmer, Christoph A1 - Sadak, A. E. A1 - Heßling, L. A1 - Lüdicke, M. A1 - Bilsel, M. A1 - Horn, Wolfgang A1 - Richter, Matthias T1 - Polymer Capsules with Volatile Organic Compounds as Reference Materials for Controlled Emission N2 - Encapsulation of volatile organic compounds (VOCs) that could evaporate at a defined rate is of immense interest for application in emission reference materials (ERMs). Polyurethane/polyurea microcapsules with various VOC active ingredients (limonene, pinene, and toluene) were successfully produced by interfacial polymerization with Shirasu porous glass membrane emulsification in a size range between 10 and 50 μm. The effect of surfactant, VOC, monomer(s) type, and ratio has a great effect on the formulation process and morphology of capsules. The type of VOC played a significant role in the encapsulation efficiency. Due to the difference in vapor pressure and VOC/water interfacial tension, the formulation for encapsulation was optimized for each individual VOC. Furthermore, to achieve effective stability of the large droplets/capsules, a combination of ionic and nonionic surfactants was used. Optical and scanning electron microscopy, Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA), were used to characterize the optimized microcapsules. The results showed that the obtained microcapsules exhibited a spherical shape and core–shell morphology and featured characteristic urethane-urea bonds. The amount of encapsulated VOC ranges between 54 and 7 wt %. The emission tests were performed with the help of the emission test chamber procedure (EN 16516). The limonene-loaded polyurethane/polyurea microcapsules show a change in emission rate of less than 10% within 14 days and can be considered as a potential candidate for use as an ERM. KW - Polymer microcapsules KW - Membrane emulsification KW - Polyaddition KW - Volatile organic compound (VOC) KW - Emission testing PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-619227 DO - https://doi.org/10.1021/acsami.4c12826 SN - 1944-8252 VL - 16 IS - 50 SP - 69999 EP - 70009 PB - ACS AN - OPUS4-61922 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Berkes, L. A1 - Nehring, Grzegorz A1 - Bonnerot, O. A1 - Krutzsch, M. A1 - Rabin, Ira A1 - Richter, T. S. T1 - Mixed Inks in Two Coptic Documents from the Hermopolite Region Relating to Lease Business N2 - In this article, we present two Coptic papyri, P 11934 and P 11935 from the Berlin collection excavated in Ashmunein (ancient Hermopolis) by Otto Rubensohn in 1906. We employ a multi-disciplinary approach that takes into account both their materiality – writing support as well as ink – and their content, as has become ‘best practice’. 1 Material aspects of written documents have traditionally been the purview of papyrologists. Recently developed methods of scientific analysis generate sets of archaeometric data with the potential to improve understanding of the materiality of ancient document production, as well as to yield new evidence for genuine papyrological research questions. To achieve this, a large corpus of comparative data needs to be built. Our contribution offers a first step in this direction. We aim at presenting the papyri, which were selected because of the ink corrosion during conservation work at the Berlin collection, in a format that is exhaustive both for material and textual aspects. The inks from both papyri were analysed using a combination of techniques, contributing to our better understanding of the development of ink technology in Late Antiquity. KW - Coptic papyri KW - Methods of scientific analysis KW - Sets of archaeometric data KW - Mixed Inks KW - Ink corrosion KW - Ancient document production PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-579948 DO - https://doi.org/10.48631/pylon.2023.3.98234 SN - 2751-4722 VL - 2023/3 IS - 3 SP - 1 EP - 18 PB - Ceative Commons Attribution ShareAlike CY - Heidelberg, Germany AN - OPUS4-57994 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Richter, Anja A1 - Possling, A. A1 - Malysheva, N. A1 - Yousef, K. P. A1 - Herbst, S. A1 - von Kleist, M. A1 - Hengge, R. T1 - Local c-di-GMP signaling in the control of synthesis of the E. coli biofilm exopolysaccharide pEtN-cellulose N2 - In many bacteria, the biofilm-promoting second messenger c-di-GMP is produced and degraded by multiple diguanylate cyclases (DGC) and phosphodiesterases (PDE), respectively. High target specificity of some of these enzymes has led to theoretical concepts of "local" c-di-GMP signaling. In Escherichia coli K-12, which has 12 DGCs and 13 PDEs, a single DGC, DgcC, is specifically required for the biosynthesis of the biofilm exopolysaccharide pEtN-cellulose without affecting the cellular c-di-GMP pool, but the mechanistic basis of this target specificity has remained obscure. DGC activity of membrane-associated DgcC, which is demonstrated in vitro in nanodiscs, is shown to be necessary and sufficient to specifically activate cellulose biosynthesis in vivo. DgcC and a particular PDE, PdeK (encoded right next to the cellulose operon), directly interact with cellulose synthase subunit BcsB and with each other, thus establishing physical proximity between cellulose synthase and a local source and sink of c-di-GMP. This arrangement provides a localized, yet open source of c-di-GMP right next to cellulose synthase subunit BcsA, which needs allosteric activation by c-di-GMP. Through mathematical modeling and simulation, we demonstrate that BcsA binding from the low cytosolic c-di-GMP pool in E. coli is negligible, whereas a single c-di-GMP molecule that is produced and released in direct proximity to cellulose synthase increases the probability of c-di-GMP binding to BcsA several hundred-fold. This local c-di-GMP signaling could provide a blueprint for target-specific second messenger signaling also in other bacteria where multiple second messenger producing and degrading enzymes exist. KW - Biofilm KW - Cellulose synthase KW - Bacterial second messenger KW - C-di-GMP PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-511214 DO - https://doi.org/10.1016/j.jmb.2020.06.006 SN - 0022-2836 VL - 432 IS - 16 SP - 4576 EP - 4595 PB - Elsevir Ltd. AN - OPUS4-51121 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schwibbert, Karin A1 - de Eulate Pérez, Elisa García A1 - Wen, Keqing A1 - Voss, Heike A1 - Thiele, Dorothea A1 - Richter, Anja M. A1 - Bonse, Jörn T1 - Escherichia coli repellence via laser-induced periodic surface structures (LIPSS) on titanium: Critical role of biofilm-associated gene expression N2 - The inconsistency in the observed bacteria-repellent effects of laser-induced surface textures remains a subject of scientific debates. With E. coli TG1 as test strain, we performed biofilm formation assays on ultrashort pulse laser textured titanium. Samples covered with low spatial frequency LIPSS (LSFL) of periods around 750 nm or with high spatial frequency LIPSS (HSFL) featuring smaller periods around 100 nm were processed on polished samples. While LSFL significantly reduce the number of adhering bacteria compared to the polished reference, HSFL do not. Simultaneously, we concentrate our study on bacterial strategies employed for biofilm formation, that is the transcription of the biofilm-associated genes csgB, involved in primary adhesion to a surface, and wza, participating in biofilm maturation. Promoter regions of these genes were cloned into a promotor probe plasmid with the green fluorescent protein GFP+ as reporter and transferred into the test strain. As indicated by the fluorescence intensity of the reporter protein, among the bacteria colonizing LSFL-covered areas, a markedly higher proportion of cells transcribing csgB or wza were detected, compared to the bacterial populations colonizing the polished or HSFL-covered areas. To our knowledge, this is the first study indicating that the antifouling effect of LSFL topographies can be counteracted when bacteria activate biofilm-associated genes. KW - Laser-induced periodic surface structures (LIPSS) KW - Titanium KW - Biofilm KW - Antifouling KW - Gene expression KW - Fluorescence microscopy PY - 2026 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-655572 DO - https://doi.org/10.1016/j.apsusc.2026.166363 SN - 0169-4332 VL - 730 SP - 1 EP - 9 PB - Elsevier B.V. AN - OPUS4-65557 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -