Generalized boundary triples, II : some applications of generalized boundary triples and form domain invariant Nevanlinna functions. - In: Mathematische Nachrichten, ISSN 1522-2616, Bd. 295 (2022), 6, S. 1113-1162
The paper is a continuation of Part I and contains several further results on generalized boundary triples, the corresponding Weyl functions, and applications of this technique to ordinary and partial differential operators. We establish a connection between Post's theory of boundary pairs of closed nonnegative forms on the one hand and the theory of generalized boundary triples of nonnegative symmetric operators on the other hand. Applications to the Laplacian operator on bounded domains with smooth, Lipschitz, and even rough boundary, as well as to mixed boundary value problem for the Laplacian are given. Other applications concern with the momentum, Schrödinger, and Dirac operators with local point interactions. These operators demonstrate natural occurrence of ES$ES$-generalized boundary triples with domain invariant Weyl functions and essentially selfadjoint reference operators A0.
https://doi.org/10.1002/mana.202000049
Linear port-Hamiltonian systems are generically controllable. - In: IEEE transactions on automatic control, ISSN 1558-2523, Bd. 67 (2022), 6, S. 3220-3222
The new concept of relative generic subsets is introduced. It is shown that the set of controllable linear finite-dimensional port-Hamiltonian systems is a relative generic subset of the set of all linear finite-dimensional port-Hamiltonian systems. This implies that a random, continuously distributed port-Hamiltonian system is almost surely controllable.
https://doi.org/10.1109/TAC.2021.3098176
Silicon carbide - graphene nano-gratings on 4H and 6H semi-insulating SiC. - In: Materials science forum, ISSN 1662-9752, Bd. 1062 (2022), S. 170-174
A technical methodology of fabrication of hierarchically scaled multitude graphene nanogratings with varying pitches ranging from the micrometer down to sub 40 nm scale combined with sub 10 nm step heights on 4H and 6H semi-insulating SiC for length scale measurements is proposed. The nanogratings were fabricated using electron-beam lithography combined with dry etching of graphene, incorporating a standard semiconductor processing technology. A scientific evaluation of critical dimension, etching step heights, and surface characterization of graphene nanograting on both polytypes were compared and evaluated.
https://doi.org/10.4028/p-wn4zya
Funnel MPC with feasibility constraints for nonlinear systems with arbitrary relative degree. - In: IEEE control systems letters, ISSN 2475-1456, Bd. 6 (2022), S. 2804-2809
We study tracking control for nonlinear systems with known relative degree and stable internal dynamics by the recently introduced technique of Funnel MPC. The objective is to achieve the evolution of the tracking error within a prescribed performance funnel. We propose a novel stage cost for Funnel MPC, extending earlier designs to the case of arbitrary relative degree, and show that the control objective as well as initial and recursive feasibility are always achieved - without requiring any terminal conditions or a sufficiently long prediction horizon. We only impose an additional feasibility constraint in the optimal control problem.
https://doi.org/10.1109/LCSYS.2022.3178478
Novel whitlockite/alginate/C60 fullerene composites: synthesis, characterization and properties for medical application. - In: The Arabian journal for science and engineering, ISSN 2191-4281, Bd. 47 (2022), 6, S. 7093-7104
The hybrid composite materials in form of spheres based on whitlockite-related calcium phosphate, Alginate (20, 30 or 50 wt.%) and C60 Fullerene (C60; 2 or 5 wt.%) were fabricated. According to XRD, elemental analysis and SEM data, the whitlockite-related (hexagonal system, space group R3c) calcium phosphate containing 0.42 wt.% of sodium was obtained in the form of particles with size 50-80 nm. It has been found that the addition of Alginate (20 wt.%) to prepared calcium phosphate leads to an increase in the compressive strength of composite by two times (from 137 to 358 MPa), and value of Young's modulus on 20% (from 460 to 558 MPa), while the presence of C60 in composition did not significant influence on this characteristic. The antibacterial activity of prepared composites with different composition and amounts (2.5, 5 or 10 mM) against Lactobacillus rhamnosus, Lactobacillus salivarius, Staphylococcus aureus and Pseudomonas aeruginosa was studied. All prepared samples did not effect on Lactobacillus. The addition of 5 wt.% C60 to phosphate-Alginate (30 wt.%) composite resulted in a tenfold decrease in the survival rate of the S. aureus strain at 5 and 10 mM of samples while P. aeruginosa was less sensitive to action of this sample and inhibition of bacteria growth was occurred only at its amount 10 mM. Thus, the results of mechanical properties and impact of created nanostructured hybrid composites on normal human microbiota (Lactobacillus) as well as pathogenic strain (S. aureus and P. aeruginosa) indicate the suitability of these promising materials for further biological test for bone therapy.
https://doi.org/10.1007/s13369-021-06552-0
Rational design of electrolyte solvation structures for modulating 2e-/4e- transfer in sodium-air batteries. - In: Advanced functional materials, ISSN 1616-3028, Bd. 32 (2022), 23, 2201258, S. 1-11
In sodium-air batteries (SABs), achieving the regulation of the electron transfer number during oxygen reduction reactions (ORRs) in the same electrolyte system remains a significant challenge. In this work, a promising strategy is proposed to dynamically modulate 2e-/4e- transfer in ORRs by regulating the electrolyte structures to realize the different performances of SABs. The 4e- ORR can be realized by decreasing the electrolyte concentration. The solvation sheath of Na+ at dilute concentrations consists mainly of water molecules that hinder the access of Na+ to the cathode surface due to the high solvation energies indicated by theoretical calculations, thereby impeding the 2e- reaction. In contrast, excess free water can easily access the cathode surface and trigger the 4e- ORR. The solvation energies of Na+ can be remarkably reduced by increasing the electrolyte concentration, forming a water-in-salt unit, in which the Na+ mainly coordinates with the bis(fluorosulfonyl)imide anion and can be easily released from the solvation sheath. Hence, the 2e- ORR is significantly promoted and becomes the dominant reaction. The SAB based on the 2e- reaction exhibits excellent energy density (15980 Wh kg-1) and good cycle performance (300 times), and the 4e- reaction exhibits excellent power density (12.09 mW cm-2).
https://doi.org/10.1002/adfm.202201258
A vectorization scheme for nonconvex set optimization problems. - In: SIAM journal on optimization, ISSN 1095-7189, Bd. 32 (2022), 2, S. 1184-1209
In this paper, we study a solution approach for set optimization problems with respect to the lower set less relation. This approach can serve as a base for numerically solving set optimization problems by using established solvers from multiobjective optimization. Our strategy consists of deriving a parametric family of multiobjective optimization problems whose optimal solution sets approximate, in a specific sense, that of the set-valued problem with arbitrary accuracy. We also examine particular classes of set-valued mappings for which the corresponding set optimization problem is equivalent to a multiobjective optimization problem in the generated family. Surprisingly, this includes set-valued mappings with a convex graph.
https://doi.org/10.1137/21M143683X
An overview of metal-organic frameworks-derived carbon as anode materials for sodium- and potassium-ion batteries. - In: Materials Today Sustainability, ISSN 2589-2347, Bd. 18 (2022), 100156
With the decreasing abundance of lithium and the increasing cost of lithium-ion batteries (LIBs), exploring alternative metal-ion batteries has been a hotspot in the energy storage research area. Among next-generation batteries, sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs) have been considered as competitive alternatives to LIBs due to the earth abundance of sodium and potassium. Metal-organic frameworks (MOFs)-derived carbon materials with high porosity, unique architectures, and abundant heteroatoms have been demonstrated as promising anode materials in SIBs and PIBs with high capacity and long cycling stability due to the adsorption energy storage mechanism. In this review, we highlight the advantages of carbon materials derived from MOFs as anode materials in SIBs and PIBs. In addition, the typical works and recent achievements are also introduced. Finally, the challenges and perspectives for further developing MOFs-derived carbon anode materials for SIBs and PIBs are also discussed.
https://doi.org/10.1016/j.mtsust.2022.100156
Analysis of biomechanical and biochemical markers of rat muscle soleus fatigue processes development during long-term use of C60 fullerene and N-acetylcysteine. - In: Nanomaterials, ISSN 2079-4991, Bd. 12 (2022), 9, 1552, S. 1-15
The development of an effective therapy aimed at restoring muscle dysfunctions in clinical and sports medicine, as well as optimizing working activity in general remains an urgent task today. Modern nanobiotechnologies are able to solve many clinical and social health problems, in particular, they offer new therapeutic approaches using biocompatible and bioavailable nanostructures with specific bioactivity. Therefore, the nanosized carbon molecule, C60 fullerene, as a powerful antioxidant, is very attractive. In this study, a comparative analysis of the dynamic of muscle soleus fatigue processes in rats was conducted using 50 Hz stimulation for 5 s with three consistent pools after intraperitoneal administration of the following antioxidants: C60 fullerene (a daily dose of 1 mg/kg one hour prior to the start of the experiment) and N-acetylcysteine (NAC; a daily dose of 150 mg/kg one hour prior to the start of the experiment) during five days. Changes in the integrated power of muscle contraction, levels of the maximum and minimum contraction force generation, time of reduction of the contraction force by 50% of its maximum value, achievement of the maximum force response, and delay of the beginning of a single contraction force response were analyzed as biomechanical markers of fatigue processes. Levels of creatinine, creatine phosphokinase, lactate, and lactate dehydrogenase, as well as pro- and antioxidant balance (thiobarbituric acid reactive substances, hydrogen peroxide, reduced glutathione, and catalase activity) in the blood of rats were analyzed as biochemical markers of fatigue processes. The obtained data indicate that applied therapeutic drugs have the most significant effects on the 2nd and especially the 3rd stimulation pools. Thus, the application of C60 fullerene has a (50-80)% stronger effect on the resumption of muscle biomechanics after the beginning of fatigue than NAC on the first day of the experiment. There is a clear trend toward a positive change in all studied biochemical parameters by about (12-15)% after therapeutic administration of NAC and by (20-25)% after using C60 fullerene throughout the experiment. These findings demonstrate the promise of using C60 fullerenes as potential therapeutic nanoagents that can reduce or adjust the pathological conditions of the muscular system that occur during fatigue processes in skeletal muscles.
https://doi.org/10.3390/nano12091552
Effect of fullerene C60 thermal and tribomechanical loading on Raman signals. - In: Diamond and related materials, ISSN 0925-9635, Bd. 126 (2022), 109036, S. 1-14
Fullerene C60 powder was loaded by 1 N normal force and exposed to sliding under different frequencies for 15 min. It is shown that the velocity of the sliding movement determines the stability of the fullerene C60 powder. At slow velocity of movement with a frequency of 1 Hz under 1 N normal force, the fullerene C60 structure remains undamaged after 15 min sliding. On the contrary, high sliding velocities of 10 Hz and 50 Hz affected fragmentation of the fullerene C60, which resulted in a reduction of the coefficient of friction (COF). During sliding with 1 Hz, the friction reached the highest level with an average COF of 0.59 ± 0.03. The faster relative motion under 1 N normal force gave a lower average COF with 0.39 ± 0.03. The initial fullerene C60 powder formed a thick compressed layer in the tribomechanical loaded zone. As proven by Raman spectroscopy, operating the tribomechanical sliding test at 50 Hz stimulated the re-attraction of fresh C60 fullerene island onto the fragmented layer from outside of the loaded powder regions. The COF was increasing again up to 0.44 ± 0.04 for 1 N normal force and 50 Hz frequency. The fragmentation and decomposition of fullerene C60 with increasing sliding velocity is attributed to thermal heating up during fast relative movement. Raman spectra of the tribomechanical loaded fullerene C60 are compared with Raman spectra from slowly heated up C60 in air and with Raman spectra of laser irradiated fullerene C60.
https://doi.org/10.1016/j.diamond.2022.109036