Erscheinungsjahr 2021

Anzahl der Treffer: 85
Erstellt: Wed, 27 Mar 2024 23:37:59 +0100 in 0.0590 sec


Visaveliya, Nikunjkumar R.; Mazétyté-Stasinskiené, Raminta; Köhler, Michael
General background of SERS sensing and perspectives on polymer-supported plasmon-active multiscale and hierarchical sensor particles. - In: Advanced optical materials, ISSN 2195-1071, Bd. 10 (2022), 4, 2102001, S. 1-27

Surface-enhanced Raman scattering (SERS) is one of the most powerful analytical techniques for the identification of molecules. The substrate, on which SERS is dependent, contains regions of nanoscale gaps (hotspots) that hold the ability to concentrate incident electromagnetic fields and effectively amplify vibrational scattering signals of adsorbed analytes. While surface plasmon resonance from metal nanostructures is a central focus for the SERS effect, the support of polymers can be significantly advantageous to provide larger exposure of structured metal surfaces for efficient interactions with analytes. Characteristics of the polymer particles such as softness, flexibility, swellability, porosity, optical transparency, metal-loading ability, and high surface area can allow diffusion of analytes and penetrating light deeply that can enormously amplify sensing outcomes. As polymer-supported plasmon-active sensor particles can emerge as versatile SERS substrates, the microfluidic platform is promising for the generation of sensor particles as well as for performing sequential SERS analysis of multiple analytes. Therefore, in this perspective article, the development of multifunctional polymer-metal composite particles, and their applications as potential sensors for SERS sensing through microfluidics are presented. A detailed background from the beginning of the SERS field and perspectives for the multifunctional sensor particles for efficient SERS sensing are provided.



https://doi.org/10.1002/adom.202102001
Ispirli, Mehmet Murat; Kalenderli, Özcan; Seifert, Florian; Rock, Michael; Oral, Bülent
Investigation of impact of DC component on breakdown characteristics for different electric fields under composite AC & DC voltage. - In: High voltage, ISSN 2397-7264, Bd. 7 (2022), 2, S. 279-287

https://doi.org/10.1049/hve2.12185
Fiedler, Patrique; Fonseca, Carlos; Supriyanto, Eko; Zanow, Frank; Haueisen, Jens
A high-density 256-channel cap for dry electroencephalography. - In: Human brain mapping, ISSN 1097-0193, Bd. 43 (2022), 4, S. 1295-1308

High-density electroencephalography (HD-EEG) is currently limited to laboratory environments since state-of-the-art electrode caps require skilled staff and extensive preparation. We propose and evaluate a 256-channel cap with dry multipin electrodes for HD-EEG. We describe the designs of the dry electrodes made from polyurethane and coated with Ag/AgCl. We compare in a study with 30 volunteers the novel dry HD-EEG cap to a conventional gel-based cap for electrode-skin impedances, resting state EEG, and visual evoked potentials (VEP). We perform wearing tests with eight electrodes mimicking cap applications on real human and artificial skin. Average impedances below 900 k[Ohm] for 252 out of 256 dry electrodes enables recording with state-of-the-art EEG amplifiers. For the dry EEG cap, we obtained a channel reliability of 84% and a reduction of the preparation time of 69%. After exclusion of an average of 16% (dry) and 3% (gel-based) bad channels, resting state EEG, alpha activity, and pattern reversal VEP can be recorded with less than 5% significant differences in all compared signal characteristics metrics. Volunteers reported wearing comfort of 3.6 ± 1.5 and 4.0 ± 1.8 for the dry and 2.5 ± 1.0 and 3.0 ± 1.1 for the gel-based cap prior and after the EEG recordings, respectively (scale 1-10). Wearing tests indicated that up to 3,200 applications are possible for the dry electrodes. The 256-channel HD-EEG dry electrode cap overcomes the principal limitations of HD-EEG regarding preparation complexity and allows rapid application by not medically trained persons, enabling new use cases for HD-EEG.



https://doi.org/10.1002/hbm.25721
Camargo, Magali K.; Uebel, Martin; Kurniawan, Mario; Ziegler, Karl F.; Seiler, Michael; Grieseler, Rolf; Schmidt, Udo; Barz, Andrea; Bliedtner, Jens; Bund, Andreas
Selective metallization of polymers: surface activation of polybutylene terephthalate (PBT) assisted by picosecond laser pulses. - In: Advanced engineering materials, ISSN 1527-2648, Bd. 24 (2022), 4, 2100933, S. 1-15

https://doi.org/10.1002/adem.202100933
Gao, Yueyue; Cui, Minghuan; Qu, Shengchun; Zhao, Huaping; Shen, Zhitao; Tan, Furui; Dong, Yulian; Qin, Chaochao; Wang, Zhijie; Zhang, Weifeng; Wang, Zhangguo; Lei, Yong
Efficient organic solar cells enabled by simple non-fused electron donors with low synthetic complexity. - In: Small, ISSN 1613-6829, Bd. 18 (2022), 3, 2104623, insges. 10 S.

https://doi.org/10.1002/smll.202104623
Li, Feitao; Oliva Ramírez, Manuel; Wang, Dong; Schaaf, Peter
Effect of SiO2 interlayer thickness in Au/SiO2/Si multilayer systems on Si sources and the formation of Au-based nanostructures. - In: Advanced materials interfaces, ISSN 2196-7350, Bd. 9 (2022), 2, 2101493, insges. 9 S.

Si sources involved in the growth of Au-SiOx nanostructures are investigated through the rapid thermal annealing of gold thin films on SiO2/Si substrates with various SiO2 layer thicknesses (3, 25, 100, 500 nm) in a reducing atmosphere. This method reveals three Si sources whose involvement depends on the thickness of the SiO2 layers, i.e., Si diffusion from the substrate, and SiO from SiO2 decomposition and from Si active oxidation. Increasing thicknesses of the SiO2 layer hampers the Si diffusion and the decomposition of regions of the SiO2 layer, which decreases the concentrations of discovered regions weakening the Si active oxidation. These discovered regions appear in systems with a SiO2 layer of 25 or 100 nm, while they are absent for a 500 nm layer. Furthermore, Au-SiOx nanostructures of different shapes form in each system. Both behaviors indicate that the influence and transport mechanisms of the different Si sources are largely dependent on the thicknesses of the SiO2 layers and that they control the evolution of the Au-SiOx nanostructures. A clear understanding of the relationship between these thicknesses and the possible Si sources and their roles in the evolution of the nanostructures makes the tailored fabrication of nanostructures possible.



https://doi.org/10.1002/admi.202101493
Eichfelder, Gabriele; Groetzner, Patrick
A note on completely positive relaxations of quadratic problems in a multiobjective framework. - In: Journal of global optimization, ISSN 1573-2916, Bd. 82 (2022), 3, S. 615-626

In a single-objective setting, nonconvex quadratic problems can equivalently be reformulated as convex problems over the cone of completely positive matrices. In small dimensions this cone equals the cone of matrices which are entrywise nonnegative and positive semidefinite, so the convex reformulation can be solved via SDP solvers. Considering multiobjective nonconvex quadratic problems, naturally the question arises, whether the advantage of convex reformulations extends to the multicriteria framework. In this note, we show that this approach only finds the supported nondominated points, which can already be found by using the weighted sum scalarization of the multiobjective quadratic problem, i.e. it is not suitable for multiobjective nonconvex problems.



https://doi.org/10.1007/s10898-021-01091-2
Eichfelder, Gabriele; Warnow, Leo
An approximation algorithm for multi-objective optimization problems using a box-coverage. - In: Journal of global optimization, ISSN 1573-2916, Bd. 83 (2022), 2, S. 329-357

For a continuous multi-objective optimization problem, it is usually not a practical approach to compute all its nondominated points because there are infinitely many of them. For this reason, a typical approach is to compute an approximation of the nondominated set. A common technique for this approach is to generate a polyhedron which contains the nondominated set. However, often these approximations are used for further evaluations. For those applications a polyhedron is a structure that is not easy to handle. In this paper, we introduce an approximation with a simpler structure respecting the natural ordering. In particular, we compute a box-coverage of the nondominated set. To do so, we use an approach that, in general, allows us to update not only one but several boxes whenever a new nondominated point is found. The algorithm is guaranteed to stop with a finite number of boxes, each being sufficiently thin.



https://doi.org/10.1007/s10898-021-01109-9
Jibril, Muhammad Attahir; Götze, Philipp; Broneske, David; Sattler, Kai-Uwe
Selective caching : a persistent memory approach for multi-dimensional index structures. - In: Distributed and parallel databases, ISSN 1573-7578, Bd. 40 (2022), 1, S. 47-66
Special Issue on Self-Managing and Hardware-Optimized Database Systems 2020

https://doi.org/10.1007/s10619-021-07327-0
Merker, Lukas; Behn, Carsten; Zimmermann, Klaus
Soft touch between a highly flexible bio-inspired tactile sensor and 3D objects. - In: Proceedings in applied mathematics and mechanics, ISSN 1617-7061, Bd. 21 (2021), 1, e202100003, S. 1-3

Scanning and reconstructing the environment using tactile sensors alongside optical sensors is a promising approach in mobile robotics. Within the present paper, we take advantage of a recently presented vibrissa-inspired tactile sensor concept for 3D object scanning and reconstruction, broadening our previous studies. The sensor consists of a slender, cylindrical, highly flexible probe, one-sided clamped to some force-torque measuring device. The probe is shifted relatively to an object of interest by displacing its clamping position quasi-statically. Consequently, the probe gets bent, sweeps over the object and transmits mechanical signals (observables) to its support. The focus of the present investigation is on how the probe sweeps over a new type of object (paraboloid), verifying a necessary condition for optional contact points. Finally, this condition allows to find multiple equilibrium states for a single clamping position.



https://doi.org/10.1002/pamm.202100003