23 results
Search Results
Now showing 1 - 10 of 23
- ItemApplication of scanning electrochemical microscopy for topography imaging of supported lipid bilayers(Cambridge : RSC Publ., 2022) Nasri, Zahra; Memari, Seyedali; Striesow, Johanna; Weltmann, Klaus-Dieter; von Woedtke, Thomas; Wende, KristianOxidative stress in cellular environments may cause lipid oxidation and membrane degradation. Therefore, studying the degree of lipid membrane morphological changes by reactive oxygen and nitrogen species will be informative in oxidative stress-based therapies. This study introduces the possibility of using scanning electrochemical microscopy as a powerful imaging technique to follow the topographical changes of a solid-supported lipid bilayer model induced by reactive species produced from gas plasma. The introduced strategy is not limited to investigating the effect of reactive species on the lipid bilayer but could be extended to understand the morphological changes of the lipid bilayer due to the action of membrane proteins or antimicrobial peptides.
- ItemBeyond graphene oxide: Laser engineering functionalized graphene for flexible electronics(Cambridge : RSC Publ., 2020) Rodriguez, Raul D.; Khalelov, Alimzhan; Postnikov, Pavel S.; Lipovka, Anna; Dorozhko, Elena; Amin, Ihsan; Murastov, Gennadiy V.; Chen, Jin-Ju; Sheng, Wenbo; Trusova, Marina E.; Chehimi, Mohamed M.; Sheremet, EvgeniyaCarbon nanomaterials, especially graphene, are promising due to their abundance and the possibility to exploit them in lightweight, flexible, and wearable electronics enabling paradigms such as the Internet of Things. However, conventional methods to synthesize and integrate graphene into functional materials and flexible devices are either hazardous, time demanding, or excessively energy-consuming. To overcome these issues, here we propose a new concept based on the laser processing of single-layer diazonium-functionalized graphene. This is a safe, inexpensive, and environmentally-friendly method making it a competitive alternative for graphene-device fabrication. Flexible chemiresistors exhibit sensitivity for breath (water vapor and CO2) and ethanol detection up to 1500% higher than laser-reduced graphene oxide devices. We attribute this enhanced sensitivity to an optimal balance between structural defects and electrical conductivity. Flexible electronic circuits demonstrate a superb resilience against scratching and high current stability up to 98% with durability against 180° bending cycles for continuous operation of several weeks. This work can impact biomedical technology and electronics where tunable electrical conductivity, sensitivity, and mechanical stability are of uttermost importance. © 2020 The Royal Society of Chemistry.
- ItemOptical microresonator arrays of fluorescence-switchable diarylethenes with unreplicable spectral fingerprints(Cambridge : RSC Publ., 2020) Okada, Daichi; Lin, Zhan-Hong; Huang, Jer-Shing; Oki, Osamu; Morimoto, Masakazu; Liu, Xuying; Minari, Takeo; Ishii, Satoshi; Nagao, Tadaaki; Irie, Masahiro; Yamamoto, YoheiHigh-security identification requires authentication that is hard to counterfeit and replicate. For anti-counterfeiting data storage and rewritable memory devices, chromic materials are adoptable, where the dichromatic colours can be switched by external stimuli. If further individual information is embedded in each pixel, a much higher-level security system beyond the zero/one data array will be realized. For this purpose, a fine whispering gallery mode (WGM) fingerprint pattern from a microresonator is applicable. Here we propose that photoswitchable optical microresonators made of a fluorescent photochromic organic material function as anti-counterfeiting, rewritable optical memories. The WGM photoluminescence of the resultant microspheres can be switched on and off repeatedly by irradiation with ultraviolet and visible light. The shape of the microresonator varies from a sphere to an oblate ellipsoid and hemisphere, depending on the self-assembly process, and the WGM spectral pattern depends sensitively on the morphology of the resonators. Furthermore, surface self-assembly on a hydrophobic/hydrophilic micropatterned substrate affords a highly integrated array of microresonators as dense as millions of pixels per square centimetre. The spectral fingerprints of all pixels are different from one another; therefore, the photoswitchable microarrays are applicable as an ultimate anti-counterfeiting system which is hard to replicate. This journal is © 2020 The Royal Society of Chemistry.
- ItemPatterning and control of the nanostructure in plasma thin films with acoustic waves: mechanical vs. electrical polarization effects(Cambridge : RSC Publ., 2021) García-Valenzuela, Aurelio; Fakhfouri, Armaghan; Oliva-Ramírez, Manuel; Rico-Gavira, Victor; Rojas, Teresa Cristina; Alvarez, Rafael; Menzel, Siegfried B.; Palmero, Alberto; Winkler, Andreas; González-Elipe, Agustín R.Nanostructuration and 2D patterning of thin films are common strategies to fabricate biomimetic surfaces and components for microfluidic, microelectronic or photonic applications. This work presents the fundamentals of a surface nanotechnology procedure for laterally tailoring the nanostructure and crystalline structure of thin films that are plasma deposited onto acoustically excited piezoelectric substrates. Using magnetron sputtering as plasma technique and TiO2 as case example, it is demonstrated that the deposited films depict a sub-millimetre 2D pattern that, characterized by large lateral differences in nanostructure, density (up to 50%), thickness, and physical properties between porous and dense zones, reproduces the wave features distribution of the generated acoustic waves (AW). Simulation modelling of the AW propagation and deposition experiments carried out without plasma and under alternative experimental conditions reveal that patterning is not driven by the collision of ad-species with mechanically excited lattice atoms of the substrate, but emerges from their interaction with plasma sheath ions locally accelerated by the AW-induced electrical polarization field developed at the substrate surface and growing film. The possibilities of the AW activation as a general approach for the tailored control of nanostructure, pattern size, and properties of thin films are demonstrated through the systematic variation of deposition conditions and the adjustment of AW operating parameters.
- ItemErratum: Exploring the 3D structure and defects of a self-assembled gold mesocrystal by coherent X-ray diffraction imaging (Nanoscale (2021) DOI: 10.1039/D1NR01806J)(Cambridge : RSC Publ., 2021) Carnis, Jerome; Kirner, Felizitas; Lapkin, Dmitry; Sturm, Sebastian; Kim, Young Yong; Baburin, Igor A.; Khubbutdinov, Ruslan; Ignatenko, Alexandr; Iashina, Ekaterina; Mistonov, Alexander; Steegemans, Tristan; Wieck, Thomas; Gemming, Thomas; Lubk, Axel; Lazarev, Sergey; Sprung, Michael; Vartanyants, Ivan A.; Sturm, Elena V.Correction for ‘Exploring the 3D structure and defects of a self-assembled gold mesocrystal by coherent X-ray diffraction imaging’ by Jerome Carnis et al., Nanoscale, 2021, DOI: 10.1039/D1NR01806J.
- ItemEther functionalisation, ion conformation and the optimisation of macroscopic properties in ionic liquids(Cambridge : RSC Publ., 2020) Philippi, Frederik; Rauber, Daniel; Kuttich, Björn; Kraus, Tobias; Kay, Christopher W.M.; Hempelmann, Rolf; Hunt, Patricia A.; Welton, TomIonic liquids are an attractive material class due to their wide liquid range, intrinsic ionic conductivity, and high chemical as well as electrochemical stability. However, the widespread use of ionic liquids is hindered by significantly higher viscosities compared to conventional molecular solvents. In this work, we show how the transport properties of ionic liquids can be altered significantly, even for isostructural ions that have the same backbone. To this end, structure–property relationships have been determined for a set of 16 systematically varied representative ionic liquids. Variations in molecular structure include ammonium vs. phosphonium, ether vs. alkyl side chains, and rigid vs. flexible anions. Ab initio calculations are used to relate molecular structures to the thermal, structural and transport properties of the ionic liquids. We find that the differences in properties of ether and alkyl functionalised ionic liquids are primarily dependent on minimum energy geometries, with the conformational flexibility of ether side chains appearing to be of secondary importance. We also show unprecedented correlations between anion conformational flexibility and transport properties. Critically, increasing fluidity upon consecutive introduction of ether side chains and phosphonium centres into the cation is found to be dependent on whether the anion is flexible or rigid. We demonstrate that targeted design of functional groups based on structure–property relationships can yield ionic liquids of exceptionally high fluidity.
- ItemPerspectives on weak interactions in complex materials at different length scales(Cambridge : RSC Publ., 2022) Fiedler, J.; Berland, K.; Borchert, J.W.; Corkery, R. W.; Eisfeld, A.; Gelbwaser-Klimovsky, D.; Greve, M.M.; Holst, B.; Jacobs, K.; Krüger, M.; Parsons, D. F.; Persson, C.; Presselt, M.; Reisinger, T.; Scheel, S.; Stienkemeier, F.; Tømterud, M.; Walter, M.; Weitz, R.T.; Zalieckas, J.Nanocomposite materials consist of nanometer-sized quantum objects such as atoms, molecules, voids or nanoparticles embedded in a host material. These quantum objects can be exploited as a super-structure, which can be designed to create material properties targeted for specific applications. For electromagnetism, such targeted properties include field enhancements around the bandgap of a semiconductor used for solar cells, directional decay in topological insulators, high kinetic inductance in superconducting circuits, and many more. Despite very different application areas, all of these properties are united by the common aim of exploiting collective interaction effects between quantum objects. The literature on the topic spreads over very many different disciplines and scientific communities. In this review, we present a cross-disciplinary overview of different approaches for the creation, analysis and theoretical description of nanocomposites with applications related to electromagnetic properties.
- ItemAnion and ether group influence in protic guanidinium ionic liquids(Cambridge : RSC Publ., 2023) Rauber, Daniel; Philippi, Frederik; Becker, Julian; Zapp, Josef; Morgenstern, Bernd; Kuttich, Björn; Kraus, Tobias; Hempelmann, Rolf; Hunt, Patricia; Welton, Tom; Kay, Christopher W. M.Ionic liquids are attractive liquid materials for many advanced applications. For targeted design, in-depth knowledge about their structure-property-relations is urgently needed. We prepared a set of novel protic ionic liquids (PILs) with a guanidinium cation with either an ether or alkyl side chain and different anions. While being a promising cation class, the available data is insufficient to guide design. We measured thermal and transport properties, nuclear magnetic resonance (NMR) spectra as well as liquid and crystalline structures supported by ab initio computations and were able to obtain a detailed insight into the influence of the anion and the ether substitution on the physical and spectroscopic properties. For the PILs, hydrogen bonding is the main interaction between cation and anion and the H-bond strength is inversely related to the proton affinity of the constituting acid and correlated to the increase of 1H and 15N chemical shifts. Using anions from acids with lower proton affinity leads to proton localization on the cation as evident from NMR spectra and self-diffusion coefficients. In contrast, proton exchange was evident in ionic liquids with triflate and trifluoroacetate anions. Using imide-type anions and ether side groups decreases glass transitions as well as fragility, and accelerated dynamics significantly. In case of the ether guanidinium ionic liquids, the conformation of the side chain adopts a curled structure as the result of dispersion interactions, while the alkyl chains prefer a linear arrangement.
- ItemPolarization-dependent vibrational shifts on dielectric substrates(Cambridge : RSC Publ., 2020) Yang, C.; Wang, W.; Nefedov, A.; Wang, Y.; Mayerhöfer, T.G.; Wo¨ll, C.The interaction of light with matter at surfaces of dielectrics strongly depends on polarization. Here, we present the first infrared spectroscopic evidence for significant polarization effects in the spectroscopic detection of adsorbate vibrational frequencies. In addition to much larger peak intensities for p-polarized light relative to s-polarization, a small but distinct blue shift was identified for CO adsorbed at the surfaces of two prototype dielectric substrates, CeO2(111) and CaCO3(10.4). A simulation using a layer model yields very good agreement with experiment.
- ItemTailoring the stoichiometry of C3N4 nanosheets under electron beam irradiation(Cambridge : RSC Publ., 2021) Mendes, Rafael G.; Ta, Huy Q.; Yang, Xiaoqin; Bachmatiuk, Alicja; Praus, Petr; Mamakhel, Aref; Iversen, Bo B.; Su, Ren; Gemming, Thomas; Rümmeli, Mark H.Two-dimensional polymeric graphitic carbon nitride (g-C3N4) is a low-cost material with versatile properties that can be enhanced by the introduction of dopant atoms and by changing the degree of polymerization/stoichiometry, which offers significant benefits for numerous applications. Herein, we investigate the stability of g-C3N4 under electron beam irradiation inside a transmission electron microscope operating at different electron acceleration voltages. Our findings indicate that the degradation of g-C3N4 occurs with N species preferentially removed over C species. However, the precise nitrogen group from which N is removed from g-C3N4 (C–N–C, [double bond, length as m-dash]NH or –NH2) is unclear. Moreover, the rate of degradation increases with decreasing electron acceleration voltage, suggesting that inelastic scattering events (radiolysis) dominate over elastic events (knock-on damage). The rate of degradation by removing N atoms is also sensitive to the current density. Hence, we demonstrate that both the electron acceleration voltage and the current density are parameters with which one can use to control the stoichiometry. Moreover, as N species were preferentially removed, the d-spacing of the carbon nitride structure increased. These findings provide a deeper understanding of g-C3N4.
- «
- 1 (current)
- 2
- 3
- »