Washability of e-textiles: current testing practices and the need for standardization

Washability is seen as one of the main obstacles that stands in the way of a wider market success of e-textile products. So far, there are no standardized methods for wash testing of e-textiles and no protocols to comparably assess the washability of tested products. Thus, different e-textiles that are deemed equally washable by their developers might present with very different ranges of reliability after repeated washing. This paper presents research into current test practices in the absence of e-textile-specific standards. Different testing methods are compared and evaluated and the need for standardized testing, giving e-textile developers the tools to comparably communicate and evaluate their products’ washability, is emphasized

Design for Recycling of E-Textiles: Current Issues of Recycling of Products Combining Electronics and Textiles and Implications for a Circular Design Approach

Circular economy principles and eco-design guidelines such as design for recycling gain increasing importance to improve recyclability of products. The market of textiles with electronic components—so-called electronic textiles (e-textiles)–grows quickly entailing an increase in waste due to obsolete and defect products. This chapter presents insights into the current state of e-textile recycling in Europe. As electronic recycling differs from textile recycling, a survey of sorting and recycling businesses in Europe was conducted to obtain insights into the current and future handling of e-textiles. The survey results reveal that e-textiles have so far played a minor role for sorting and recycling companies, but about one-third of the businesses already experienced issues in recycling e-textiles. While some of the respondents have already developed processing concepts, the overall occurrence of e-textiles is so low that businesses are unlikely to develop recycling solutions. However, with increasing market volume, waste will also increase and recycling requires improvement to reduce environmental impact. Based on the survey results, recommendations for improving the recyclability and recycling rate of e-textiles are proposed. This includes expanding the scope of current regulations to e-textiles to apply guidelines for integrating sustainable end-of-life solutions in the product design process, acknowledging current shortcomings of the recycling industry

Perturbation theory and the two-level approximation:A corollary and critique

This analysis addresses the use of a two-level approximation to simplify expressions derived from perturbation theory. It is shown that the limitations of validity for the emergent results are more stringent than is commonly understood, being equivalent in effect to the adoption of a more extensive approximation - one that significantly undermines the perturbative origin of those expressions. Effectively truncating the completeness relation, a series of interconnected operator relations comes into play, some with physically untenable consequences. A new theorem on the expectation values of operator functions highlights additional constraints upon any molecule modelled as a two-level system. © 2010 Elsevier B.V. All rights reserved

Radiochemical determination of 129I and 36Cl inMEGAPIE, a proton irradiated lead-bismuth eutectic spallation target

The concentrations of the long-lived nuclear reaction products 129I and 36Cl have been measured in samples from the MEGAPIE liquid metal spallation target. Samples from the bulk target material (lead-bismuth eutectic, LBE), from the interface of the metal free surface with the cover gas, from LBE/steel interfaces and from noble metal absorber foils installed in the cover gas system were analysed using Accelerator Mass Spectrometry at the Laboratory of Ion beam Physics at ETH Zürich. The major part of 129I and 36Cl was found accumulated on the interfaces, particularly at the interface of LBE and the steel walls of the target container, while bulk LBE samples contain only a minor fraction of these nuclides. Both nuclides were also detected on the absorber foils to a certain extent (≪ 1% of the total amount). The latter number is negligible concerning the radio-hazard of the irradiated target material; however it indicates a certain affinity of the absorber foils for halogens, thus proving the principle of using noble metal foils for catching these volatile radionuclides. The total amounts of 129I and 36Cl in the target were estimated from the analytical data by averaging within the different groups of samples and summing up these averages over the total target. This estimation could account for about half of the amount of 129I and 36Cl predicted to be produced using nuclear physics modelling codes for both nuclides. The significance of the results and the associated uncertainties are discussed

Washable, Low-Temperature Cured Joints for Textile-Based Electronics

Low-temperature die-attaching pastes for wearable electronics are the key components to realize any type of device where components are additively manufactured by pick and place techniques. In this paper, the authors describe a simple method to realize stretchable, bendable, die-attaching pastes based on silver flakes to directly mount resistors and LEDs onto textiles. This paste can be directly applied onto contact pads placed on textiles by means of screen and stencil printing and post-processed at low temperatures to achieve the desired electrical and mechanical properties below 60 °C without sintering. Low curing temperatures lead to lower power consumption, which makes this paste ecological friendly

Excitation-transcription coupling in skeletal muscle: the molecular pathways of exercise

Muscle fibres have different properties with respect to force, contraction speed, endurance, oxidative/glycolytic capacity etc. Although adult muscle fibres are normally post-mitotic with little turnover of cells, the physiological properties of the pre-existing fibres can be changed in the adult animal upon changes in usage such as after exercise. The signal to change is mainly conveyed by alterations in the patterns of nerve-evoked electrical activity, and is to a large extent due to switches in the expression of genes. Thus, an excitation-transcription coupling must exist. It is suggested that changes in nerve-evoked muscle activity lead to a variety of activity correlates such as increases in free intracellular Ca2+ levels caused by influx across the cell membrane and/or release from the sarcoplasmatic reticulum, concentrations of metabolites such as lipids and ADP, hypoxia and mechanical stress. Such correlates are detected by sensors such as protein kinase C (PKC), calmodulin, AMP-activated kinase (AMPK), peroxisome proliferator-activated receptor δ (PPARδ), and oxygen dependent prolyl hydroxylases that trigger intracellular signaling cascades. These complex cascades involve several transcription factors such as nuclear factor of activated T-cells (NFAT), myocyte enhancer factor 2 (MEF2), myogenic differentiation factor (myoD), myogenin, PPARδ, and sine oculis homeobox 1/eyes absent 1 (Six1/Eya1). These factors might act indirectly by inducing gene products that act back on the cascade, or as ultimate transcription factors binding to and transactivating/repressing genes for the fast and slow isoforms of various contractile proteins and of metabolic enzymes. The determination of size and force is even more complex as this involves not only intracellular signaling within the muscle fibres, but also muscle stem cells called satellite cells. Intercellular signaling substances such as myostatin and insulin-like growth factor 1 (IGF-1) seem to act in a paracrine fashion. Induction of hypertrophy is accompanied by the satellite cells fusing to myofibres and thereby increasing the capacity for protein synthesis. These extra nuclei seem to remain part of the fibre even during subsequent atrophy as a form of muscle memory facilitating retraining. In addition to changes in myonuclear number during hypertrophy, changes in muscle fibre size seem to be caused by alterations in transcription, translation (per nucleus) and protein degradation

Tailoring intra- and intermolecular properties : from cyclophanes to daisy chains

Todays high-tech society is striving for faster, cheaper and higher performing devices in all circumstances. Traditional materials have long since reached their limits making the search for new materials with altered properties inevitable. Easy processable, long-term stable polymeric materials with improved handling or switchable properties for use in plastics, conducting single molecular wires, switches, rectifiers in computer industry, nonlinear optic materials for data transmission at the speed of light, devices for flexible displays and luminescent materials operating with less energy are needed in the nearby future. Hence fundamental research in material science and nanotechnology is urgently necessary to provide the base for potential future applications. Part A: The synthesis and aggregation studies of a hermaphroditic molecular rod comprising a terminal water soluble loop are presented. Functional group transformations on a mono-functionalized Diederich-type cylophane, acting as the loop subunit, containing a hydrophobic cavity and final coupling of an oligophenylene-ethynylene hydrophobic molecular rod provided the envisaged target compound in 21 or 17 synthetic steps. In polar solvents the hydrophobic rod threads into the cavity of the macrocycle driven by a strong hydrophobic effect. Aggregation studies by 1H-NMR titrations, fluorescence titrations and mass spectrometry confirmed the formation of dimers at low concentrations and longer oligomers at higher concentrations. Such molecular daisy chains are potential candidates towards new polymers with altered macroscopic properties Part B: The functionalization of the molecular rod of the amphiphilic daisy chain monomer at the terminus with thiol anchoring groups for investigations in molecular electronics is shown. Aggregation studies revealed a similar self-complexation behavior as the unfunctionalized version. Below concentrations of 0.37 mM the formation of [c2]daisy chains was observed. Such thiol-functionalized pseudorotaxanes are potential candidates for investigations of bimolecular bridges in mechanically controlled break junctions (MCBJ) potentially resulting in new design possibilities in single molecular electronics. Furthermore the mechanically adjustable stacking surface of the molecular rods allows for mimicking a macroscopic potentiometer by mechanical minute opening and closing the gap between two electrodes. Part C: Terminal piperidinyl and nitro functionalized biphenyls, bridged between 2 and 2’ position by a variable number of methylene groups, were synthesized and fully characterized. These push-pull systems with defined and restricted torsion angles between their phenyl rings are ideal model compounds to investigate the influence of the chromophore’s conjugation in nonlinear optic (NLO) responses. A general implementable synthetic route towards these model compounds is reported. NLO properties of the series of torsionally constrained push-pull biphenyls were collected by electric field induced second harmonic generation (EFISH) experiments. The results agree qualitatively with semi-empirical simulations based on the AM1 Hamiltonian. A linear dependence of the quadratic response on the cos2Φ of the inter-aryl dihedral angle is observed, which points to oscillator strength loss as the dominant effect of increasing backbone twist. To get insight into the conformational stability, the thermodynamics of the atropisomerization of these torsion angle restricted, axial chiral biphenyl based push-pull cyclophanes were studied. Using 1H-NMR coalescence and dynamic HPLC measurements the rotation barrier around the central C-C bond was determined, indicating that the tendency of the push-pull system to planarize may be considered as a driving force for the atropisomerization. Part D: The influence of 2,2’ propyl-bridged and 4,4’ electron donor or electron acceptor substituted axial chiral biphenyl cyclophanes on their atropisomerization process was studied. Estimated free energies of the rotation around the central biphenyl bond – obtained from 1H-NMR coalescence measurements – were correlated to the Hammett-parameters σp as a measure for electron donor and acceptor strength. It is demonstrated that the resulting linear correlation is mainly based on the influence of the different substituents on the π-system of the biphenyl cyclophanes. DFT calculations show a planar transition state of these isomerization processes and the calculated energy barriers based on these mechanistic studies are in good agreement with the experimentally obtained free energies. In addition the butyl-bridged derivatives were studied by dynamic HPLC. The same trends than for the propyl-bridged cyclophanes were observed. Part E: A series of mono-thiolated torsion angle restricted biphenyl based cyclophanes were synthesized. These model compounds allowed for modulation of the field-effect mobility and threshold voltage of organic thin film transistors

Induktion axialer Chiralität in einem Geländer-Oligomer durch Längendiskrepanz der Oligomerstränge

Helikale Moleküle zeigen einzigartige physikalische Eigenschaften, die auf ihre Chiralität zurückgehen. Wir beschreiben hier einen neuen Ansatz zum Aufbau von “Geländer”-Oligomeren durch Verbindung zweier unterschiedlich langer Oligomerstränge. Dabei windet sich ein längerer Oligobenzylether-Strang um ein kürzeres Oligophenyl-Rückgrat, um die Längendiskrepanz auszugleichen. Das neue Geländer-Oligomer (1) wurde durch Umwandlungen funktioneller Gruppen und Kreuzkupplungsschritte sowie interne nukleophile Cyclisierungen aufgebaut und vollständig charakterisiert, darunter durch Röntgenstrukturanalyse. Die Isolierung der reinen Enantiomere ermöglichte die Verfolgung des Racemisierungsprozesses mittels CD-Spektroskopie