Enhancing the performance of quantum reservoir computing and solving the time-complexity problem by artificial memory restriction. - In: Physical review research, ISSN 2643-1564, Bd. 6 (2024), 1, 013051, S. 013051-1-013051-11
We propose a scheme that can enhance the performance and reduce the computational cost of quantum reservoir computing. Quantum reservoir computing is a computing approach which aims at utilizing the complexity and high dimensionality of small quantum systems, together with the fast trainability of reservoir computing, in order to solve complex tasks. The suitability of quantum reservoir computing for solving temporal tasks is hindered by the collapse of the quantum system when measurements are made. This leads to the erasure of the memory of the reservoir. Hence, for every output, the entire input signal is needed to reinitialize the reservoir, leading to quadratic time complexity. Another critical issue for the hardware implementation of quantum reservoir computing is the need for an experimentally accessible means of tuning the nonlinearity of the quantum reservoir. We present an approach which addresses both of these issues. We propose artificially restricting the memory of the quantum reservoir by only using a small number inputs to reinitialize the reservoir after measurements are performed. This strongly influences the nonlinearity of the reservoir response due to the influence of the initial reservoir state, while also substantially reducing the number of quantum operations needed to perform time-series prediction tasks due to the linear rather than quadratic time complexity. The reinitialization length therefore provides an experimental accessible means of tuning the nonlinearity of the response of the reservoir, which can lead to significant task-specific performance improvement. We numerically study the linear and quadratic algorithms for a fully connected transverse Ising model and a quantum processor model.
https://doi.org/10.1103/PhysRevResearch.6.013051
Research progress on vanadium sulfide anode materials for sodium and potassium-ion batteries. - In: Advanced Materials Technologies, ISSN 2365-709X, Bd. n/a (2024), n/a, 2301840, S. 1-28
Considering environmental changes and the demand for more sustainable energy sources, stricter requirements have been placed on electrode materials for sodium and potassium-ion batteries, which are expected to provide higher energy and power density while being affordable and sustainable. Vanadium sulfide-based materials have emerged as intriguing contenders for the next generation of anode materials due to their high theoretical capacity, abundant reserves, and cost-effectiveness. Despite these advantages, challenges such as limited cycle life and restricted ion diffusion coefficients continue to impede their effective application in sodium and potassium-ion batteries. To overcome the limitations associated with electrochemical performance and circumvent bottlenecks imposed by the inherent properties of materials at the bulk scale, this review comprehensively summarizes and analyzes the crystal structures, modification strategies, and energy storage processes of vanadium sulfide-based electrode materials for sodium and potassium-ion batteries. The objective is to guide the development of high-performance vanadium-based sulfide electrode materials with refined morphologies and/or structures, employing environmentally friendly and cost-efficient methods. Finally, future perspectives and research suggestions for vanadium sulfide-based materials are presented to propel practical applications forward.
https://doi.org/10.1002/admt.202301840
Modular air-liquid interface aerosol exposure system (MALIES) to study toxicity of nanoparticle aerosols in 3D-cultured A549 cells in vitro. - In: Archives of toxicology, ISSN 1432-0738, Bd. 98 (2024), 4, S. 1061-1080
We present a novel lung aerosol exposure system named MALIES (modular air-liquid interface exposure system), which allows three-dimensional cultivation of lung epithelial cells in alveolar-like scaffolds (MatriGrids®) and exposure to nanoparticle aerosols. MALIES consists of multiple modular units for aerosol generation, and can be rapidly assembled and commissioned. The MALIES system was proven for its ability to reliably produce a dose-dependent toxicity in A549 cells using CuSO4 aerosol. Cytotoxic effects of BaSO4- and TiO2-nanoparticles were investigated using MALIES with the human lung tumor cell line A549 cultured at the air-liquid interface. Experiments with concentrations of up to 5.93 × 10^5 (BaSO4) and 1.49 × 10^6 (TiO2) particles/cm^3, resulting in deposited masses of up to 26.6 and 74.0 µg/cm^2 were performed using two identical aerosol exposure systems in two different laboratories. LDH, resazurin reduction and total glutathione were measured. A549 cells grown on MatriGrids® form a ZO-1- and E-Cadherin-positive epithelial barrier and produce mucin and surfactant protein. BaSO4-NP in a deposited mass of up to 26.6 µg/cm^2 resulted in mild, reversible damage (˜ 10% decrease in viability) to lung epithelium 24 h after exposure. TiO2-NP in a deposited mass of up to 74.0 µg/cm^2 did not induce any cytotoxicity in A549 cells 24 h and 72 h after exposure, with the exception of a 1.7 fold increase in the low exposure group in laboratory 1. These results are consistent with previous studies showing no significant damage to lung epithelium by short-term treatment with low concentrations of nanoscale BaSO4 and TiO2 in in vitro experiments.
https://doi.org/10.1007/s00204-023-03673-3
Impact of the tip-to-semiconductor contact in the electrical characterization of nanowires. - In: ACS omega, ISSN 2470-1343, Bd. 9 (2024), 5, S. 5788-5797
Well-defined semiconductor heterostructures are a basic requirement for the development of high-performance optoelectronic devices. In order to achieve the desired properties, a thorough study of the electrical behavior with a suitable spatial resolution is essential. For this, various sophisticated tip-based methods can be employed, such as conductive atomic force microscopy or multitip scanning tunneling microscopy (MT-STM). We demonstrate that in any tip-based measurement method, the tip-to-semiconductor contact is decisive for reliable and precise measurements and in interpreting the properties of the sample. For that, we used our ultrahigh-vacuum-based MT-STM coupled in vacuo to a reactor for the preparation of nanowires (NWs) with metal organic vapor phase epitaxy, and operated our MT-STM as a four-point nanoprober on III-V semiconductor NW heterostructures. We investigated a variety of upright, free-standing NWs with axial as well as coaxial heterostructures on the growth substrates. Our investigation reveals charging currents at the interface between the measuring tip and the semiconductor via native insulating oxide layers, which act as a metal-insulator-semiconductor capacitor with charging and discharging conditions in the operating voltage range. We analyze in detail the observed I-V characteristics and propose a strategy to achieve an optimized tip-to-semiconductor junction, which includes the influence of the native oxide layer on the overall electrical measurements. Our advanced experimental procedure enables a direct relation between the tip-to-NW junction and the electronic properties of as-grown (co)axial NWs providing precise guidance for all future tip-based investigations.
https://doi.org/10.1021/acsomega.3c08729
Antimetastatic lung cancer therapy using alkaloid Piperlongumine noncovalently bound to С60 fullerene. - In: Journal of drug delivery science and technology, Bd. 92 (2024), 105275, S. 1-10
A novel nanoformulation, C60 fullerene loaded with a plant alkaloid Piperlongumine (PL) molecules (C60-PL nanocomplex), as a potential drug for the treatment of highly metastatic lung cancer was created and characterized by using ultrasonic technology, computer simulation, atomic force and scanning tunneling microscopy. The aim of the study was to evaluate the antimetastatic potential of PL alone and the C60-PL nanocomplex using Lewis lung carcinoma (LLC) cell line as a model. Evidence has been obtained that the 2:1C60-PL nanocomplex is a potent agent capable of effectively reducing the survival, migration and invasion of LLC cells in vitro, as well as tumor growth and metastasis in vivo compared to free PL. These effects in cell behavior were shown to be associated with an increased Bax expression and high level of cleaved PARP confirming the proapototic potential of C60-PL nanocomplex as well as down-regulation of the mRNA of epithelial-mesenchymal transition regulator Twist1 and cancer stem cell marker CD44, a reduced level of phosphorylated mTOR and adaptor protein Ruk/CIN85. Histological analysis of the lung tissue of LLC-bearing mice showed that in animals that received the C60-PL nanocomplex, the regression of metastases prevailed over their growth. The obtained results allow to conclude that the proposed C60-PL nanocomplex represents a promising drug for the treatment of metastatic lung cancer.
https://doi.org/10.1016/j.jddst.2023.105275
Multi-strategy coordination enables WSe2 to achieve high-performance real-world detection of NO2. - In: Sensors and actuators, ISSN 0925-4005, Bd. 403 (2024), 135183, S. 1-10
In recent years, WSe2 has become an ideal material for room-temperature NO2 gas sensing, but its low response and long response time limit its application. In this study, we combined multiple strategies of constructing a three-dimensional structure, introducing Se vacancies, Au nanoparticle sensitization, and 1 T/2 H-phase modulation. The synergistic effect was utilized to effectively enhance the gas adsorption, charge transfer degree, and carrier transport capacity of WSe2 and achieve high-performance NO2 detection. The prepared V-WAAP achieved high response (78.32%) with a short response time (33 s), and outstanding stability and selectivity for low concentration (1 ppm) NO2. The intrinsic factors of sensing performance improvement were comprehensively analyzed by combining the results of compositional and structural characterization. In addition, we verified its potential for practical applications by assembling a V-WAAP-based NO2 gas sensing equipment.
https://doi.org/10.1016/j.snb.2023.135183
Research progress of transition metal compounds as bifunctional catalysts for zinc-air batteries. - In: Nano research energy, ISSN 2790-8119, Bd. 3 (2024), 1, e9120092, S. 1-23
Zinc-air batteries (ZABs) are widely studied because of their high theoretical energy density, high battery voltage, environmental protection, and low price. However, the slow kinetics of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) on the air electrode limits the further application of ZABs, so that how to develop a cheap, efficient, and stable catalyst with bifunctional catalytic activity is the key to solving the development of ZABs. Transition metal compounds are widely used as cathode materials for ZABs due to their low cost, high electrocatalytic activity, and stable structure. This review summarizes the research progress of transition metal compounds as bifunctional catalysts for ZABs. The development history, operation principle, and mechanism of ORR and OER reactions are introduced first. The application and development of transition metal compounds as bifunctional catalysts for ZABs in recent years are systematically introduced, including transition metal oxides (TMOs), transition metal nitrides (TMNs), transition metal sulfides (TMSs), transition metal carbides (TMCs), transition metal phosphates (TMPs), and others. In addition, the shortcomings of transition metal compounds as bifunctional catalysts for ZABs were summarized and reasonable design strategies and improvement measures were put forward, aiming at providing a reference for the design and construction of high-performance ZABs cathode materials. Finally, the challenges and future in this field are discussed and prospected.
https://doi.org/10.26599/NRE.2023.9120092
Dissociation of singlet excitons dominates photocurrent improvement in high-efficiency non-fullerene organic solar cells. - In: Nano research energy, ISSN 2790-8119, Bd. 3 (2024), 1, e9120099, S. 1-8
In organic solar cells, the singlet and triplet excitons dissociate into free charge carriers with different mechanisms due to their opposite spin state. Therefore, the ratio of the singlet and triplet excitons directly affects the photocurrent. Many methods were used to optimize the performance of the low-efficiency solar cell by improving the ratio of triplet excitons, which shows a long diffusion length. Here we observed that in high-efficiency systems, the proportion of singlet excitons under linearly polarized light excitation is higher than that of circularly polarized light. Since the singlet charge transfer state has lower binding energy than the triplet state, it makes a significant contribution to the charge carrier generation and enhancement of the photocurrent. Further, the positive magnetic field effect reflects that singlet excitons dissociation plays a major role in the photocurrent, which is opposite to the case of low-efficiency devices where triplet excitons dominate the photocurrent.
https://doi.org/10.26599/NRE.2023.9120099
Self-dual convolutional codes. - In: IEEE transactions on information theory, Bd. 70 (2024), 2, S. 950-963
This paper investigates the concept of self-dual convolutional codes. We derive the basic properties of this interesting class of codes and we show how some of the techniques to construct self-dual linear block codes generalize to self-dual convolutional codes. As for self-dual linear block codes we are able to give a complete classification for some small parameters.
https://doi.org/10.1109/TIT.2023.3343108
Set-based robust optimization of uncertain multiobjective problems via epigraphical reformulations. - In: European journal of operational research, ISSN 0377-2217, Bd. 313 (2024), 3, S. 871-882
In this paper, we study a method for finding robust solutions to multiobjective optimization problems under uncertainty. We follow the set-based minmax approach for handling the uncertainties which leads to a certain set optimization problem with the strict upper type set relation. We introduce, under some assumptions, a reformulation using instead the strict lower type set relation without sacrificing the compactness property of the image sets. This allows to apply vectorization results to characterize the optimal solutions of these set optimization problems as optimal solutions of a multiobjective optimization problem. We end up with multiobjective semi-infinite problems which can then be studied with classical techniques from the literature.
https://www.sciencedirect.com/science/article/pii/S0377221723007208/pdfft?md5=f5272f8643b0ce953294091001149d0f&pid=1-s2.0-S0377221723007208-main.pdf