Publications at the Department of Mathematics and Natural Sciences from 2019

Results: 873
Created on: Thu, 28 Mar 2024 23:08:02 +0100 in 0.0996 sec


Mathew, Sobin; Reiprich, Johannes; Narasimha, Shilpashree; Abedin, Saadman; Kurtash, Vladislav; Thiele, Sebastian; Scheler, Theresa; Hähnlein, Bernd; Schaaf, Peter; Jacobs, Heiko O.; Pezoldt, Jörg
Gate-tunable hysteresis response of field effect transistor based on sulfurized Mo. - In: AIP Advances, ISSN 2158-3226, Bd. 13 (2023), 9, 095224, S. 095224-1-095224-7

Hysteresis effects and their tuning with electric fields and light were studied in thin film molybdenum disulfide transistors fabricated from sulfurized molybdenum films. The influence of the back-gate voltage bias, voltage sweep range, illumination, and AlOx encapsulation on the hysteresis effect of the back-gated field effect transistors was studied and quantified. This study revealed the distinctive contribution of MoS2 surface, MoS2/SiO2 interface defects and their associated traps as primary sources of of hysteresis.



https://doi.org/10.1063/5.0165868
Espuny Díaz, Alberto; Hyde, Joseph
Powers of Hamilton cycles in dense graphs perturbed by a random geometric graph. - In: European journal of combinatorics, Bd. 0 (2023), 0, 103848

Let G be a graph obtained as the union of some n-vertex graph Hn with minimum degree δ (Hn) ≥ αn and a d-dimensional random geometric graph Gd (n,r). We investigate under which conditions for r the graph G will a.a.s. contain the kth power of a Hamilton cycle, for any choice of Hn. We provide asymptotically optimal conditions for r for all values of α, d and k. This has applications in the containment of other spanning structures, such as F-factors.



https://doi.org/10.1016/j.ejc.2023.103848
Hou, Minjie; Zhou, Yingjie; Liang, Feng; Zhao, Huaping; Ji, Deyang; Zhang, Da; Li, Liqiang; Lei, Yong
Research progress of solid electrolyte interphase for sodium metal anodes. - In: The chemical engineering journal, ISSN 1873-3212, Bd. 475 (2023), 146227

Inhomogeneous and fragile solid electrolyte interphase (SEI) leads to poor battery cycle life and safety hazards, which is a key challenge that limits the practical application of low-cost sodium metal anodes. Although sodium metal batteries based on non-aqueous liquid and solid electrolytes have made great progress in terms of interfacial chemistry and SEI regulation strategies, the relevant evaluation of SEI from the perspective of the electrolyte is not well understood. This paper reviews the formation mechanism, physicochemical properties, and failure mechanism of SEI at the interface between the sodium metal and the liquid/solid electrolyte, focusing on poor stability, compatibility, interfacial ion transport problems, and influencing factors. Recent advances in SEI regulation are summarized in terms of electrolytes, artificial interphases, and electrode engineering to achieve ideal electrochemical reversibility. The effectiveness of the SEI engineering strategies was evaluated based on a comprehensive review of the interfacial stability in different electrolyte systems. Finally, the challenges associated with rational interface design for long-lasting sodium metal batteries are discussed, along with promising avenues for the same.



https://doi.org/10.1016/j.cej.2023.146227
Bartel, Andreas; Günther, Michael; Jacob, Birgit; Reis, Timo
Operator splitting based dynamic iteration for linear differential-algebraic port-Hamiltonian systems. - In: Numerische Mathematik, ISSN 0945-3245, Bd. 155 (2023), 1, S. 1-34

A dynamic iteration scheme for linear differential-algebraic port-Hamiltonian systems based on Lions-Mercier-type operator splitting methods is developed. The dynamic iteration is monotone in the sense that the error is decreasing and no stability conditions are required. The developed iteration scheme is even new for linear port-Hamiltonian systems governed by ODEs. The obtained algorithm is applied to a multibody system and an electrical network.



https://doi.org/10.1007/s00211-023-01369-5
Hou, Shengping; Xie, Zhipeng; Zhang, Da; Yang, Bin; Lei, Yong; Liang, Feng
High-purity graphene and carbon nanohorns prepared by base-acid treated waste tires carbon via direct current arc plasma. - In: Environmental research, ISSN 1096-0953, Volume 238 (2023), part 1, 117071

As the accumulation of waste tires continues to rise year by year, effectively managing and recycling these discarded materials has become an urgent global challenge. Among various potential solutions, pyrolysis stands out due to its superior environmental compatibility and remarkable efficiency in transforming waste tires into valuable products. Thus, it is considered the most potential method for disposing these tires. In this work, waste tire powder is pyrolyzed at 560 ˚C to yield pyrolysis carbon black, and meanwhile, the purification effects of base-acid solutions on pyrolysis carbon black are discussed. High-purity few-layer graphene flakes and carbon nanohorns are synthesized by a direct current arc plasma with H2 and N2 as buffer gases and high-purity pyrolysis carbon black as raw material. Under an H2 atmosphere, hydrogen effectively terminates the suspended carbon bonds, preventing the formation of closed structures and facilitating the expansion of graphene sheets. During the preparation of carbon nanohorns, the nitrogen atoms rapidly bond with carbon atoms, forming essential C-N bonds. This nitrogen doping promotes the formation of carbon-based five-membered and seven-membered rings and makes the graphite lamellar change in the direction of towards negative curvature. Consequently, such change facilitates the formation of conical structures, ultimately yielding the coveted carbon nanohorns. This work not only provides an economical raw material for efficient large-scale synthesis of few-layer graphene and carbon nanohorns but also broadens the intrinsic worth of pyrolysis carbon black, which is beneficial to improving the recycling value of waste tires.



https://doi.org/10.1016/j.envres.2023.117071
Finkelmeyer, Sarah; Askins, Erik J.; Eichhorn, Jonas; Ghosh, Soumik; Siegmund, Carmen; Täuscher, Eric; Dellith, Andrea; Hupfer, Maximilian; Dellith, Jan; Ritter, Uwe; Strzalka, Joseph; Glusac, Ksenija; Schacher, Felix; Presselt, Martin
Tailoring the weight of surface and intralayer edge states to control LUMO energies. - In: Advanced materials, ISSN 1521-4095, Bd. 35 (2023), 40, 2305006, S. 1-11

The energies of the frontier molecular orbitals determine the optoelectronic properties in organic films, which are crucial for their application, and strongly depend on the morphology and supramolecular structure. The impact of the latter two properties on the electronic energy levels relies primarily on nearest-neighbor interactions, which are difficult to study due to their nanoscale nature and heterogeneity. Here, an automated method is presented for fabricating thin films with a tailored ratio of surface to bulk sites and a controlled extension of domain edges, both of which are used to control nearest-neighbor interactions. This method uses a Langmuir–Schaefer-type rolling transfer of Langmuir layers (rtLL) to minimize flow during the deposition of rigid Langmuir layers composed of π-conjugated molecules. Using UV–vis absorption spectroscopy, atomic force microscopy, and transmission electron microscopy, it is shown that the rtLL method advances the deposition of multi-Langmuir layers and enables the production of films with defined morphology. The variation in nearest-neighbor interactions is thus achieved and the resulting systematically tuned lowest unoccupied molecular orbital (LUMO) energies (determined via square-wave voltammetry) enable the establishment of a model that functionally relates the LUMO energies to a morphological descriptor, allowing for the prediction of the range of accessible LUMO energies.



https://doi.org/10.1002/adma.202305006
Yu, Yan; He, Guping; Zhu, Ximiao; Yu, Jiahai; Shi, Yiwen; Lei, Yong; Sun, Fengqiang
A flexible humidity sensor constructed by ordered-pore-array of slightly reduced graphene oxide with much enhanced sensing response. - In: Surfaces and Interfaces, ISSN 2468-0230, Bd. 41 (2023), 103204

Reduced graphene oxide (rGO) flexible film humidity sensor has received increasing attention, but the low sensing response caused by lack of available hydrophilic functional groups is still a limitation. Herein, a slightly reduced graphene oxide (SrGO) ordered-pore-array, fabricated via a monolayer colloid crystal template method, was introduced as a resistive humidity sensor. It was obtained based on adsorption between the GO sheets and the template microspheres, in-situ slight reduction of the GO shells and the removal of template. The reduction way allows the functional groups of GO to be retained as much as possible, and the unique structures (e.g., spherical double surfaces and small through-holes on pore-walls) facilitate the substantial exposure of functional groups, the penetration of water molecules and the utilization of buried functional groups. The available functional groups are thereby efficiently increased, giving the sensor an unprecedented high sensing response, more than 2600 times the maximum response of existing rGO sensors. The sensor also demonstrated excellent practical characteristics, and by detecting a single exhale, it could be employed in quick and quantitative evaluation of human activities and health. This strategy paves a facile and promising route to improve the sensing response and application of graphene-based humidity sensors or gas sensors.



https://doi.org/10.1016/j.surfin.2023.103204
Kumar, Niranjan; Panda, Kalpataru; Pleshkov, Roman S.; Nezhdanov, Aleksey V.; Polkovnikov, Vladimir N.; Yunin, Pavel A.; Chkhalo, Nikolay I.
High thermal stability of the reflectivity of Be/Al multilayer mirrors designed for extreme ultraviolet wavelength. - In: Surfaces and Interfaces, ISSN 2468-0230, Volume 42 (2023), part A, 103404

Superior optical contrast due to the combination of beryllium and aluminum in periodic Be/Al multilayers is the reason for effective reflectivity of these mirrors at extreme ultraviolet wavelength i.e. 17 nm. Depending on the thickness of the layers and annealing temperature, microstructure of beryllium and aluminum layers in periodic multilayers was investigated by Raman scattering spectroscopy and X-ray diffraction. Thinner film of beryllium showed more ordered structure which is qualitatively determined by narrow linewidth of optical phonon. The nucleation and grain growth of beryllium and aluminum is observed at higher annealing temperature. However, the effect of annealing on the modification of microstructure of beryllium and aluminum at lower temperature 373 K is not observed. This is the reason for almost similar value of reflectivity of ∼ 55 % for as-deposited and thermally annealed mirror at 373 K. At higher annealing temperature, the complete loss of reflectivity is observed, associated with the destruction of periodic modulation of mirrors due to interdiffusion, nucleation and grain growth of beryllium and aluminum.



https://doi.org/10.1016/j.surfin.2023.103414
Zeußel, Lisa; Singh, Sukhdeep
Meldrum’s acid furfural conjugate MAFC: a new entry as chromogenic sensor for specific amine identification. - In: Molecules, ISSN 1420-3049, Bd. 28 (2023), 18, 6627, S. 1-17

Bioactive amines are highly relevant for clinical and industrial application to ensure the metabolic status of a biological process. Apart from this, generally, amine identification is a key step in various bioorganic processes ranging from protein chemistry to biomaterial fabrication. However, many amines have a negative impact on the environment and the excess intake of amines can have tremendous adverse health effects. Thus, easy, fast, sensitive, and reliable sensing methods for amine identification are strongly searched for. In the past few years, Meldrum’s acid furfural conjugate (MAFC) has been extensively explored as a starting material for the synthesis of photoswitchable donor-acceptor Stenhouse adducts (DASA). DASA formation hereby results from the rapid reaction of MAFC with primary and secondary amines, which has so far been demonstrated through numerous publications for different applications. The linear form of the MAFC-based DASA exhibits intense pink coloration due to its linear conjugated triene-2-ol conformation, which has inspired researchers to use this easy synthesizable molecule as an optical sensor for primary, secondary, and biogenic amines. Due to its new entry into amine identification, a collection of the literature exclusively on MAFC is demanded. In this mini review, we intend to present the state-of-the-art of MAFC as an optical molecular sensor in hopes to motivate researchers to find even more applications of MAFC-based sensors and methods that pave the way to their usage in medicinal applications.



https://doi.org/10.3390/molecules28186627
Rakhmanova, Saparboy; Trunk, Carsten; Matrasulov, Davronbek
Quantum particle under dynamical confinement: from quantum Fermi acceleration to high harmonic generation. - Ilmenau : Technische Universität Ilmenau, Institut für Mathematik, 2023. - 1 Online-Ressource (15 Seiten). - (Preprint ; M23,09)

Quantum dynamics of a particle confined in a box with time-dependent wall is revisited by considering some unexplored aspects of the problem. In particular, the case of dynamical confinement in a time-dependent box in the presence of purely time-varying external potential is treated by obtaining exact solution. Also, some external potentials approving separation of space and time variables in the Schrödinger equation with time-dependent boundary conditions are classified. Time-dependence of the average kinetic energy and average quantum force are analyzed. A model for optical high harmonic generation in the presence of dynamical confinement and external linearly polarized monochromatic field is proposed.



https://nbn-resolving.org/urn:nbn:de:gbv:ilm1-2023200218