TY - CHAP AB - Electrospinning can be used to prepare nanofiber mats from diverse polymers, polymer blends and embed-ded nanoparticles. Especially nanofiber mats from biopolymers promote cell growth for wound healing, tis-sue engineering or other biotechnological applications. These materials, however, are often not stable at high temperatures, which makes sterilization challenging. The paper discusses sterilization methods, a comparison of different biopolymer blends for cell growth, and the influence of vacuum ultraviolet irradia-tion (VUV) and plasma treatment on cell growth and adhesion on electrospun nanofiber mats. This mini-review thus serves as a base for researchers working on the improvement of nanofiber mats for mammalian cell growth, giving some general ideas as well as interesting special findings. AU - Ehrmann, Andrea ED - Guxho, Genti ED - Kosova Spahiu, Tatjana ED - Prifti, Valma ED - Gjeta, Ardit ED - Xhafka, Eralda ED - Sulejmani, Anis ID - 4369 SN - 2522-5022 T2 - Proceedings of the Joint International Conference: 10th Textile Conference and 4th Conference on Engineering and Entrepreneurship TI - Electrospun Nanofiber Mats for Mammalian Cell Growth ER - TY - JOUR AB - Algae-based biopolymers can be used in diverse energy-related applications, such as separators and polymer electrolytes in batteries and fuel cells and also as microalgal biofuel, which is regarded as a highly renewable energy source. For these purposes, different physical, thermochemical, and biochemical properties are necessary, which are discussed within this review, such as porosity, high temperature resistance, or good mechanical properties for batteries and high energy density and abundance of the base materials in case of biofuel, along with the environmental aspects of using algae-based biopolymers in these applications. On the other hand, bacterial biopolymers are also often used in batteries as bacterial cellulose separators or as biopolymer network binders, besides their potential use as polymer electrolytes. In addition, they are also regarded as potential sustainable biofuel producers and converters. This review aims at comparing biopolymers from both aforementioned sources for energy conversion and storage. Challenges regarding the production of algal biopolymers include low scalability and low cost-effectiveness, and for bacterial polymers, slow growth rates and non-optimal fermentation processes often cause challenges. On the other hand, environmental benefits in comparison with conventional polymers and the better biodegradability are large advantages of these biopolymers, which suggest further research to make their production more economical. AU - Joshi, Jnanada Shrikant AU - Langwald, Sarah Vanessa AU - Ehrmann, Andrea AU - Sabantina, Lilia ID - 4374 IS - 5 JF - Polymers KW - microalgal biofuel KW - algae-based biopolymers KW - bacterial biopolymers KW - polymer electrolyte KW - batteries TI - Algae-Based Biopolymers for Batteries and Biofuel Applications in Comparison with Bacterial Biopolymers—A Review VL - 16 ER - TY - JOUR AB - Magnetic nanofibers were prepared by electrospinning polymer/metal solutions of poly(acrylonitrile) (PAN) with magnetite (Fe3O4) nanoparticles. At a mass ratio of PAN:magnetite of 2:1, the total solid content in the dimethyl sulfoxide (DMSO) solution was varied between 15 wt.% and 25 wt.%, which represents the limits of the spinnable range. The results show that the most homogeneous nanofiber mats were 21 wt.% solid contents. At 15 wt.% solid contents, a nano-membrane with some fibrous regions was produced. Nanofibers at 25 wt.% had a much larger and more inhomogeneous diameter. Nevertheless, the magnetic properties of all samples were very similar, indicating that the distribution of magnetite nanoparticles in the fibers is comparable in all samples. The results also suggested that the samples spun from solutions with near-ideal solid contents (19–21 wt.%) contain agglomerations of the nanoparticles inside the nanofibers. AU - Graciano Alvarez, Ana Karen AU - Dotter, Marius AU - Tuvshinbayar, Khorolsuren AU - Bondzio, Laila AU - Ennen, Inga AU - Hütten, Andreas AU - Blachowicz, Tomasz AU - Ehrmann, Andrea ID - 4372 IS - 3 JF - Fibers KW - electrospinning KW - magnetite KW - homogeneity KW - fiber diameter KW - alternating gradient magnetometer (AGM) TI - Electrospinning Poly(acrylonitrile) Containing Magnetite Nanoparticles: Influence of Magnetite Contents VL - 12 ER - TY - JOUR AB - 3T3 Swiss albino mouse cells are often used in biotechnological applications. These cells can grow adherently on suitable surfaces. In our study, they were grown on different titanium substrates, comparing commercially available titanium sheets of grade 1 and grade 2, respectively, with Ti64 which was 3D printed with different porosity in order to identify potential substitutes for common well-plates, which could – in case of 3D printed substrates – be produced in various shapes and dimensions and thus broaden the range of substrates for cell growth in biotechnology and tissue engineering. In addition, thin layers of poly(acrylonitrile) (PAN) nanofibers were electrospun on these substrates to add a nanostructure. The common titanium sheets showed lower cell cover factors than common well plates, which could not be improved by the thin nanofibrous coating. However, the Ti sheets with nanofiber mat coatings showed higher cell adhesion and proliferation than pure PAN nanofiber mats. The 3D printed Ti64 substrates prepared by laser metal fusion, on the other hand, enabled significantly higher proliferation of (66 ± 8)% cover factor after three days of cell growth than well plates which are usually applied as the gold standard for cell cultivation ((48 ± 11)% cover factor under identical conditions). Especially the Ti64 samples with higher porosity showed high cell adhesion and proliferation. Our study suggests investigating such porous Ti64 samples further as a potential future optimum for cell adhesion and proliferation. AU - Tanzli, Ewin AU - Kozior, Tomasz AU - Hajnys, Jiri AU - Mesicek, Jakub AU - Brockhagen, Bennet AU - Grothe, Timo AU - Ehrmann, Andrea ID - 4370 IS - 3 JF - Heliyon KW - 3T3 cell line KW - Additive manufacturing KW - Laser metal fusion KW - Powder bed fusion KW - Cell culture KW - Nanofibers SN - 24058440 TI - Improved cell growth on additively manufactured Ti64 substrates with varying porosity and nanofibrous coating VL - 10 ER - TY - JOUR AB - The exchange bias (EB) is a unidirectional anisotropy that occurs, e.g., upon field‐cooling ferromagnet/antiferromagnet systems. In many material systems, the EB field is reduced from one hysteresis loop to the next measurement. This so‐called training effect (TE) has been investigated in experiments and by means of theoretical efforts by many research groups. The reduction of the EB field as a result of subsequent magnetization reversal processes is often fitted by a power law, usually with the exception of n = 1, or with an equation based on the discretized Landau–Khalatnikov equation, as first suggested by Binek. Few other models, usually with more fitting parameters, have been proposed yet. Herein, it is shown that for large numbers of subsequent magnetization reversal processes in Co/CoO thin film samples, a modified power law or a logarithmic fit can model the TE in most cases as well as the abovementioned, commonly used models. AU - Fiedler, Johannes AU - Wortmann, Martin AU - Blachowicz, Tomasz AU - Ehrmann, Andrea ID - 4367 JF - physica status solidi (b) SN - 0370-1972 TI - Modeling the Training Effect in Exchange‐Biased Bilayers for Large Numbers of Magnetization Reversal Cycles ER - TY - JOUR AB - Textiles are used by humans for many purposes, from clothing to technical applications such as geotextiles, agrotextiles, or medical textiles. However, in addition to their importance, textiles are also responsible for various types of environmental pollution along the entire textile chain, from production, transport and trade to daily use to their end-of-life. Here we provide a brief overview of current approaches to establishing R principles in the textile industry in order to transform the recent linear structures into a circular economy and show in which areas there is a particular need for research and action. AU - Schnatmann, Anna Katharina AU - Schoden, Fabian AU - Ehrmann, Andrea AU - Schwenzfeier-Hellkamp, Eva ID - 4285 IS - 2 JF - Communications in Development and Assembling of Textile Products KW - circular economy KW - R principles KW - textile industry KW - waste prevention KW - resilience TI - R principles for circular economy in the textile industry – a mini-review VL - 4 ER - TY - CHAP AB - Planning long-term space missions, investigating growth of edible plants and fungi is of utmost importance. To investigate the behavior of plants or mushrooms in microgravity, the situation is usually simulated by using a clinostat on which the objects under investigation are slowly rotated around an axis perpendicular to the direction of gravity, in this way steadily alternating the possible gravitropic response of roots and other parts. Here we present investigations of growing Pleuratus ostreatus, an edible oyster mushroom, on a clinostat in comparison with experiments under full unmodified gravity. We show that the mycelium grew similarly in both situations on a macroscopic and a microscopic scale, suggesting that this mushroom may be suitable for growth on the ISS or on long-term manned missions. AU - Heide, Angela AU - Wiebe, Philipp AU - Sabantina, Lilia AU - Blachowicz, Tomasz AU - Ehrmann, Andrea ED - Kurt, Erol ED - Tekerek, Mehmet ID - 4366 KW - Oyster mushroom KW - P. ostreatus KW - microgravity KW - magnetic field KW - gravitropism SN - 978-625-6802-90-2 T2 - Perspectives in Engineering TI - Testing the growth of Pleurotus ostreatus in simulated microgravity by a clinostat VL - 262 ER - TY - JOUR AB - Exchange bias (EB) is a unidirectional anisotropy caused by interface coupling between a ferromagnet and an antiferromagnet. It causes a preferential direction of magnetization in the ferromagnet, which manifests as a shift of the hysteresis loop along the magnetic field axis. Here, we demonstrate a large EB of over 1000 Oe at 20 K in a twinned Co(111)/Co3O4(111) thin film epitaxially grown on sapphire(0001) with sixfold rotational lattice symmetry, which is among the highest values reported for Co/Co1−yO systems. In such systems, the effect intensity is largest along the magnetic easy axes, which usually results in an anisotropy of the EB in epitaxial interfaces. However, we observed identical EB values for 0°, 15°, and 30° angles between the magnetic field and the nearest Co[002] magnetic easy axes. The measurements imply a relaxation of the magnetization to the nearest easy axis, suggesting increasingly isotropic EB fields with higher orders of rotational lattice symmetry. AU - Wortmann, Martin AU - Samanta, Tapas AU - Gaerner, Maik AU - Westphal, Michael AU - Fiedler, Johannes AU - Ennen, Inga AU - Hütten, Andreas AU - Blachowicz, Tomasz AU - Caron, Luana AU - Ehrmann, Andrea ID - 4178 IS - 12 JF - APL Materials KW - Magnetic ordering KW - Crystallographic defects KW - Electron diffraction KW - Epitaxy KW - Ferromagnetic materials KW - Magnetic hysteresis KW - Magnetic materials KW - Thin films KW - Transmission electron microscopy KW - Solid solid interfaces TI - Isotropic exchange-bias in twinned epitaxial Co/Co3O4 bilayer VL - 11 ER - TY - BOOK AB - Three-dimensional printing is among the emerging technologies of our time. While it was previously primarily employed for rapid prototyping, this technology has entered a phase of accelerated production, especially for complicated or small objects. Most recently, novel 3D printing technologies have enabled objects with features at the micro- or even nano-scale to be fabricated. Meanwhile, well-known problems such as the waviness of fused deposition modeling (FDM)-printed parts, the missing long-term stability of some typical printing materials or the reduced mechanical properties of 3D-printed objects persist. This Special Issue focusses on all topics related to the 3D printing of micro-electromechanical systems (MEMS), such as novel or advanced features enabled by 3D printing compared to conventional technologies, but also the challenges that continue to exist regarding the application of 3D printing technologies for MEMS and new approaches to overcoming them. ED - Ehrmann, Andrea ID - 4016 KW - 3D printed nanostructures and nano-composites for application in MEMS KW - Lab-on-a-chip devices KW - Microfluidics KW - Microelectronics KW - Micro-batteries and other energy storage devices KW - Micro- and nano-sensors and -actuators (physical KW - chemical KW - biological) KW - Challenges and possible solutions of using 3D printing technologies for MEMS KW - Similar approaches related to 3D printing of MEMS technology SN - 978-3-0365-9770-6 TI - 3D Printing of MEMS Technology ER - TY - BOOK AB - Electrospinning can be used to prepare nanofibrous membranes from diverse polymers. The large surface-to-volume ratio makes them suitable for diverse fields of applications, from filters to catalysts to tissue engineering. Here, we search for the latest developments dealing with nanofiber mats for biomedicine. From wound healing to slow release, and from tissue engineering to stem cell differentiation, nanofibrous membranes can be found in a broad range of biomedical applications. For these utilizations, their chemical as well as physical properties are important, such as hydrophobicity, fiber morphology, membrane porosity, mechanical strength, etc. This Special Issue focuses on nanofibrous membranes for biomedical applications, measuring and optimizing the correlated membrane properties. It covers the full range from basic research on new materials and producing novel electrospun structure to drug release to cell growth on nanofiber mats. ED - Ehrmann, Andrea ID - 4019 KW - Nanofibrous wound dressing KW - Antibacterial KW - fungicide KW - and other properties KW - Drug release KW - Nanofibers for tissue engineering KW - Intrinsic properties of electrospun biopolymers supporting biomedical applications KW - Polymer-nanoparticle blends for nanofibers with improved properties KW - Supporting stem cell differentiation by physical and chemical means KW - Cell adhesion on nanofibrous mats KW - Optical investigation of cells grown on nanofibrous mats KW - Other examination methods KW - e.g. KW - AFM SN - 978-3-0365-7787-6 TI - Nanofibrous Membrane for Biomedical Application ER - TY - JOUR AB - The measurement of nanofiber diameters from micrographs is highly dependent on methodology and the analyst's subjective evaluation. AU - Wortmann, Martin AU - Westphal, Michael AU - Kaltschmidt, Bernhard AU - Klöcker, Michaela AU - Layland, Ashley S. AU - Brockhagen, Bennet AU - Hütten, Andreas AU - Frese, Natalie AU - Ehrmann, Andrea ID - 3749 IS - 21 JF - Nanoscale Advances TI - Nanofibers are a matter of perspective: effects of methodology and subjectivity on diameter measurements VL - 5 ER - TY - JOUR AB - Electrospun nanofiber mats have a high specific surface area and very small pores which can be tailored by the spinning process. They are thus highly suitable as filters for small particles and molecules, such as organic dyes. On the other hand, they are usually very thin and thus have low mechanical properties. As a potential reinforcement, mycelium of Pleurotus ostreatus was grown on poly(acrylonitrile) nanofiber mats and thermally solidified after fully covering the nanofiber mats. This study investigates whether the filtration efficiency of the nanofiber mats is altered by the mycelium growing through it and whether the mechanical properties of the nanofibrous filters can be improved in this way. The study shows fast and reliable growth of the mycelium on the nanofiber mats and high filtration efficiency for astra blue and chlorophyll, while indigo carmine showed only very low filtration efficiency of up to 20%. For chlorophyll and safranin, membranes with mycelium showed higher filtration than pure nanofiber mats. In diffusion cell tests, especially astra blue was strongly adsorbed on the membranes with mycelium. AU - Heide, Angela AU - Wiebe, Philip AU - Sabantina, Lilia AU - Ehrmann, Andrea ID - 3751 IS - 19 JF - Polymers KW - needleless electrospinning KW - dye filtration KW - molecular weight KW - mushroom mycelium TI - Suitability of Mycelium-Reinforced Nanofiber Mats for Filtration of Different Dyes VL - 15 ER - TY - JOUR AB - Stab-resistant clothing has been used for centuries by soldiers. Today, it is also used by policemen and other people in dangerous jobs or situations. While chain-mail or metal inserts in protective vests are heavy and uncomfortable, lightweight and bendable alternatives are currently the subject of investigation. Special textile fabrics offer a certain level of stab-resistance that can be improved by different coatings. In this study, we investigated composites of different flexible 3D printing materials, used for the fused deposition modelling (FDM) technique, on woven fabrics. Besides the adhesion between both parts of these composites, the quasi-static stab-resistant properties were investigated and compared with those of pure textile fabrics and 3D prints, respectively. AU - Cakar, Siver AU - Ehrmann, Andrea ID - 3755 JF - Tekstilec KW - 3D printing KW - fused deposition modeling (FDM) KW - flexible polymer KW - stab-resistance KW - VPAM-KDIW SN - 0351-3386 TI - Adhesion and Stab-resistant Properties of FDM-printed Polymer/Textile Composites VL - 66 ER - TY - JOUR AB - The increasing development and application of wireless devices and systems that radiate electromagnetic waves makes electromagnetic interference (EMI) shielding more and more important in everyday life. In practice, rigid EMI shields are the most commonly used ones. However, for humans or in automotive and aviation applications, flexible, drapable materials, such as textile fabrics, can be more effective and useful. Textile fabrics are usually nonconductive and not magnetic, i.e., they lack the requirements for EMI shielding. However, shielding properties of textile fabrics can be achieved by blending yarns with fine wires or coating fibers or by blending complete textile layers with conductive or magnetic materials. In this paper, shielding textile fabrics and 3D-printed materials, as references with different conductive (and partly also magnetic) properties, are examined. The measurements show a high shielding effectiveness of 80 dB given by densely woven fabrics with a thin metallic coating in the frequency range of 6.5–11 GHz, while large pores in crocheted fabrics significantly reduce the EMI shielding effectiveness, and other samples did not show shielding at all, suggesting that a combination of conductivity and the structure of the samples is responsible for the shielding potential. AU - Wójcik, Dariusz AU - Surma, Maciej AU - Magnuski, Mirosław AU - Blachowicz, Tomasz AU - Tuvshinbayar, Khorolsuren AU - Dotter, Marius AU - Topuz, Yusuf AU - Ehrmann, Andrea ID - 3758 IS - 17 JF - Applied Sciences KW - electromagnetic interference (EMI) KW - shielding effectiveness KW - conductive coating KW - metallized fabric KW - conductive yarn KW - crocheted fabric KW - porosity KW - cover factor TI - Experimental Verification of the Shielding Properties of Selected Textile Materials in the X Frequency Band VL - 13 ER - TY - CHAP AU - Ehrmann, Andrea ED - Plinke, Burkhard ED - Fischer, Sören ED - Fischer, Holger ED - Graupner, Nina ED - Müssig , Jörg ID - 3760 T2 - Charakterisierung von Holz- und Naturfasern TI - Konfokale Laserscanmikroskopie ER - TY - CONF AU - Spahiu, Tatjana AU - Ehrmann, Andrea AU - De Amorim Almeida, Henrique AU - Jimeno-Morenilla, Antonio AU - Kyratsis, Panagiotis ID - 3761 T2 - Proc. of VI Medunarodna konferencija "Savremeni trendovi i inovacije u tekstilnoj industriji" TI - Footwear products and the role of industry 4.0 for sustainable production ER - TY - CHAP AB - Electrospinning enables producing nanofibers or nanofiber mats from diverse polymers, polymer blends or polymers with embedded nanoparticles. Depending on the technology used, even core–shell structures or Janus fibers can be created. Such nanofibers can be applied in a broad range of fields, from biotechnology and biomedicine to filters and batteries. Here we give an overview of different electrospinning methods, from the needle-based technique to better upscalable needleless techniques, followed by recent developments in near-field electrospinning. Starting from the basic knowledge, each section will explain the respective techniques in detail, allowing beginners to get a first idea as well as specialists to gain most recent knowledge in the broad field of electrospinning. AU - Blachowicz, Tomasz AU - Ehrmann, Andrea ED - Das, Rasel ID - 3762 KW - Electrospinning KW - Electrospinning methods KW - Electrospinning nanofibers engineering SN - 1571-5744 T2 - Electrospun Nanofibrous Technology for Clean Water Production TI - Methods and Engineering of Electrospinning ER - TY - JOUR AB - Electrocardiogram (ECG) signals are often measured for medical purposes and in sports. While common Ag/AgCl glued gel electrodes enable good electrode skin contact, even during movements, they are not comfortable and can irritate the skin during long-term measurements. A possible alternative is textile electrodes, which have been investigated extensively during the last years. These electrodes, however, are usually not able to provide reliable, constant skin contact, resulting in reduced signal quality. Another important problem is the modification of the electrode surface due to washing or abrasion, which may impede the long-term use of such textile electrodes. Here, we report a study of washing and abrasion resistance of different ECG electrodes based on an isolating woven fabric with conductive embroidery and two conductive coatings, showing unexpectedly high abrasion resistance of the silver-coated yarn and optimum ECG signal quality for an additional coating with a conductive silicone rubber. Sheet resistances of the as-prepared electrodes were in the range of 20–30 Ω, which was increased to the range of 25–40 Ω after five washing cycles and up to approximately 50 Ω after Martindale abrasion tests. ECG measurements during different movements revealed reduced motion artifacts for the electrodes with conductive silicone rubber as compared to glued electrodes, suggesting that electronic filtering of such noise may even be easier for textile electrodes than for commercial electrodes. AU - Doci, Dajana AU - Ademi, Melisa AU - Tuvshinbayar, Khorolsuren AU - Richter, Niclas AU - Ehrmann, Guido AU - Spahiu, Tatjana AU - Ehrmann, Andrea ID - 3753 IS - 9 JF - Coatings KW - electrocardiogram (ECG) KW - textile electrodes KW - conductive coating KW - conductive yarn KW - sensor KW - Arduino TI - Washing and Abrasion Resistance of Textile Electrodes for ECG Measurements VL - 13 ER - TY - JOUR AB - A first limited approach for the automated production of crocheted fabrics was introduced in 2019. However, the knowledge on crocheted fabrics is very scarce and only few technical applications are presented in the literature. To provide a basis for possible future technical applications, the general tensile properties of crocheted fabrics are explored, and a promising application as composite reinforcement is introduced. Due to the early development state of the crochet machine prototype, conventionally hand-made crocheted fabrics are studied and the benefit of improving the machine is evaluated. The mechanical properties of crocheted fabrics depend significantly on the individual crocheter, but fabrics produced from the same person are sufficiently reproducible for reasonable investigations. Anisotropic properties with a trend toward higher resisted forces in course compared to wale direction were identified with crochets constructed from single crochet (sc) and from half double crochet (hdc) stitches. Furthermore, a tendency toward higher possible loads at larger elongations was revealed for crocheted fabrics compared to knitted ones. To the best of our knowledge, for the first time crocheted aramid fabrics were used in epoxy composites. With a crocheted reinforcement in a non-cut composite produced by vacuum-assisted hand lay-up, significantly higher ultimate tensile strength and Young’s modulus were recorded compared to a knitted one with comparable fracture modes. AU - Storck, Jan Lukas AU - Steenbock, Liska AU - Dotter, Marius AU - Funke, Herbert AU - Ehrmann, Andrea ID - 3747 JF - Journal of Engineered Fibers and Fabrics SN - 1558-9250 TI - Principle capabilities of crocheted fabrics for composite materials VL - 18 ER - TY - JOUR AB - Nanofiber mats can be electrospun by different techniques, usually subdivided into needle-based and needleless. The latter allow for producing large-area nanofiber mats, e.g., with a width of 50 cm and lengths of several meters, if electrospinning proceeds for several hours, depending on the required thickness. Even spinning smaller samples, however, raises the question of homogeneity, especially if defined mechanical properties or a defined thickness is required, e.g., for filtration purposes. Very often, only the inner parts of such electrospun nanofiber mats are used to avoid too high variation of the nanofiber mat thickness. For this study, we used wire-based electrospinning to prepare nanofiber mats with slightly varying spinning parameters. We report investigations of the thickness and mass per unit area, measured on different positions of needleless electrospun nanofiber mats. Martindale abrasion tests on different positions are added as a measure of the mechanical properties. All nanofiber mats show unexpectedly strong variations of thickness, mass per unit area, and porosity, as calculated from the apparent density of the membranes. The thickness especially varied by nearly one order of magnitude within one sample, while the apparent density, as the most uniform parameter, still showed variations by more than a factor of two within one sample. This shows that even for apparently highly homogeneous areas of such nanofiber mats, variations cannot be neglected for all potential applications. AU - Morina, Edona AU - Dotter, Marius AU - Döpke, Christoph AU - Kola, Ilda AU - Spahiu, Tatjana AU - Ehrmann, Andrea ID - 3595 IS - 18 JF - Nanomaterials TI - Homogeneity of Needleless Electrospun Nanofiber Mats VL - 13 ER -