Recent progress in transition metal based catalysts and mechanism analysis for alcohol electrooxidation reactions. - In: Green chemistry, ISSN 1463-9270, Bd. 0 (2024), 0, insges. 17 S.
In order to address energy and environmental challenges effectively, there is a need to promote renewable energy-driven electrochemical conversion technologies, particularly electrosynthesis. Electrosynthesis has the potential to convert abundant molecules into valuable chemicals and fuels. However, the widespread adoption of electrosynthesis is often hindered by the slow oxygen evolution reaction (OER). To overcome this limitation, we can employ the more efficient alcohol electrooxidation reaction (AOR), utilizing renewable biomass-derived alcohols as an alternative to OER for producing high-value chemicals. Consequently, the development of efficient AOR catalysts, in conjunction with cathodic reduction reactions (hydrogen evolution, oxygen, and nitrogen electroreduction, etc.), is crucial for sustainable and environmentally-friendly advancements. A thorough understanding of AOR mechanisms is essential for catalyst design and can be achieved through the utilization of in situ characterization techniques and density functional theory (DFT) calculations. This review summarizes recent progress in AOR catalysts, with a particular focus on the electrooxidation of monohydric alcohols, polyols, and associated studies on reaction mechanisms. Additionally, the review identifies key factors impeding AOR development and provides insights into future prospects.
https://doi.org/10.1039/D4GC00227J
Short- and long-term state switching in the superconducting niobium neuron plasticity. - In: IEEE transactions on applied superconductivity, ISSN 1558-2515, Bd. 34 (2024), 3, 1300105, insges. 5 S.
Bio-inspired algorithms and architectures are considered superior to classical architectures for certain applications. An important aspect with regard to the function of the human memory is the sorting according to important and unimportant experiences. Certain important experiences are stored significantly longer than less important ones. One criterion to make this distinction is the frequency of occurrence of a property. In this work an RSFQ circuit is presented, which performs this weighting in the learning process of a synapse. In a simulation study, the principle of the selective learning mechanism is shown to work and a variant of permanent memory is demonstrated.
https://doi.org/10.1109/TASC.2024.3355876
Der Einsatz von Mikrokugeln als Referenzartefakte für die in-situ-Charakterisierung von taktilen 3D-Mikrotastern entlang des Äquators der Tastkugel :
Using micro spheres as reference artifacts for the in-situ characterization of tactile 3D micro probes along the probing sphere’s equator. - In: Technisches Messen, ISSN 2196-7113, Bd. 91 (2024), 5, S. 244-254
Nano and micro coordinate measuring machines (CMMs) have been developed for the characterization of small dimensional features. They require a procedure which enables a traceable and precise characterization of probing spheres. In this contribution we explore the use of well characterized micro spheres as reference artifacts for the in-situ characterization of probing spheres along the probing sphere’s equator. The spheres are characterized using a strategy which is based on a set of tactile surface scans in conjunction with a stitching-algorithm. These micro spheres serve as a reference for the in-situ characterization of a tactile 3D micro probe on a nano measuring machine (NMM-1). Our investigations are based on a sample of eight spheres sourced from two different suppliers. Although the sample is small, we could already observe characteristics which seem to be typical for spheres of a certain type (i.e. nominal radius and material). The experiments indicate that micro spheres are a suitable reference artifact for tactile 3D micro probes. We were able to reproduce the measured mean radius of the probing sphere with a standard deviation of 31 nm using reference spheres whose nominal radius covers a range of 89 µm.
https://doi.org/10.1515/teme-2023-0164
A dynamic method for online measurement and calibrating with Lorentz force velocimetry. - In: Measurement science and technology, ISSN 1361-6501, Bd. 35 (2024), 6, 065008, S. 1-9
Our previous study (Zheng et al 2020 Metall. Mater. Trans. B 51 558–69; Zheng et al 2020 Acta Metall. Sin.56 929–36) reports a non-invasive in-situ measurement technology using Lorentz force velocimetry (LFV) to quantitatively measure the meniscus velocity of molten steel online. However, effective signal recognition from complex environment noise and determination of zero-point calibration in harsh metallurgical processing is an essentially challenging task and indeed needs further exploration. In this paper, a method of combining double probe arrangement with real-time differential processing technology was proposed, the twin design structure not only enables the measurement of ∼mN Lorentz forces, but also has significant characteristics of environmental tolerance. The Lorentz force signal caused by conductor motion can be accurately calculated through a differential method, meaning that the problem of zero compensation in industrial online measurement can be effectively overcome. Moreover, based on the functional correlation between the Lorentz force and the parameter of the conductor to be measured, a method of the probes moving variably and actively and their data difference ratio processing was adopted, so as to achieve dynamic calibration during online measurement. This measurement strategy provides a new approach for LFV to achieve online dynamic measurement and online calibration, and provides technical support for electromagnetic measurement technology towards engineering applications.
https://doi.org/10.1088/1361-6501/ad2f06
Wafer-scale Al junction technology for superconducting quantum circuits. - In: IEEE transactions on applied superconductivity, ISSN 1558-2515, Bd. 34 (2024), 3, 1701005, insges. 5 S.
Josephson tunnel junctions represent a key element in superconducting electronics and quantum circuits. For many years, shadow evaporation by means of Dolan-type bridges has been the state-of-the-art for deep sub- micrometer sized structures. Increasing demand in the number of Josephson junctions, e.g., in qubit circuits and travelling wave parametric amplifiers, requests for a wafer-scale fabrication process with precise control of junction parameters and have led to an advanced lift-off technique called Manhattan-type junction technology in recent years. Herein, we report on the development of a 100 mm wafer-scale fabrication technology for deep sub-micrometer sized Al Josephson junctions with linear dimensions down to 180 nm. The critical current IC of the junctions ranges from about 10 to 120 nA scaling with their linear dimensions. Low temperature transport measurements as well as room-temperature characterization has been used for IC and process homogeneity determination of series arrays of up to 50 Josephson junctions. We discuss technology parameters such as yield, on-chip and on-wafer reproducibility of the junction's critical currents as well as main process limitations. Moreover, we present experimental results on the characterization of first transmon-type qubits fabricated using this technology.
https://doi.org/10.1109/TASC.2024.3350580
Sustainable harnessing of waste polycarbonate for synthesizing activated furans to generate Stenhouse adducts on polymer surface. - In: Chemistry, ISSN 1861-471X, Bd. 0 (2024), 0, e202400369, insges. 21 S.
Plastics are versatile materials, offering lightweight, durable, and affordable solutions across various industries. However, their non-degradable nature poses challenges by end of their life. This study presented an innovative carbonyl extraction method to utilize waste poly(bisphenol A carbonate) (PC) as reaction precursor to synthesis of activated furan as precursor for photoswitchable Stenhouse adducts. This innovative chemical strategy not only generated N,N’-functionalized barbiturates but also provided an eco-friendly and cost-effective alternative to traditional synthesis methods. The method presented hereby not only promotes sustainability by repurposing waste polycarbonate as carbonyl equivalent under green conditions but also yielded reusable bisphenol A (BPA). Furthermore, the derived activated furans exhibited their functionality by forming colored donor-acceptor Stenhouse adducts (DASAs) on aminated polymer surfaces. This work demonstrated a transition from a linear plastics economy toward a circular one, highlighting the potential of plastic waste as a resource for creating materials with improved properties.
https://doi.org/10.1002/asia.202400369
Influence of increasing density of microstructures on the self-propagating reaction of Al/Ni reactive nanoscale multilayers. - In: Advanced engineering materials, ISSN 1527-2648, Bd. 0 (2024), 0, insges. 21 S.
Surface structuring methods are crucial in semiconductor manufacturing, as they enable the creation of intricate structures on the semiconductor surface, influencing the material’s electrical, mechanical, and chemical properties. This study employs one such structuring method known as reactive ion etching to create black Si structures on silicon substrates. After thermal oxidation, their influence on the reaction of Al/Ni nanoscale multilayers is. For this purpose, various densities of thermally oxidized black Si structures are investigated. It reveals distinct reactive behaviors without corresponding differences in energy release during differential scanning calorimetry measurements. Higher oxidized black Si structure densities result in elevated temperatures and faster reaction propagation, showing fewer defects and reduced layer connections in cross-sectional analyses. The properties of the reactive multilayers on high structure density show the same performance as a reaction on flat thermal SiO2, causing delamination when exceeding 23 structures per µm2. Conversely, lower structure density ensures attachment of reactive multilayers to the substrate due to an increased number of defects, acting as predetermined breaking points for the AlNi alloy. By establishing the adhesion between the reacted multilayer and the substrate, surface structuring could lead to a potential increase in bond strength when using reactive multilayers for bonding.
https://doi.org/10.1002/adem.202302225
Tailoring the reaction path: external crack initiation in reactive Al/Ni multilayers. - In: Advanced engineering materials, ISSN 1527-2648, Bd. 0 (2024), 0, 2302271, S. 1-6
The influence of intentionally externally induced cracks in reactive Al/Ni multilayer systems is investigated. These cracks affect the reaction dynamics and enable tailoring of the reaction path and the overall velocity of the reaction front. The influence of layer variations onto mechanical crack formation and resulting reaction behavior are investigated. High-speed camera imaging shows the meandering propagation of the reaction front along the crack paths. Therefore, the mechanical cracking process significantly changes the total velocity of the reaction front and thus offers a possibility to control the self-propagating high-temperature synthesis process. It is shown that the phase formation remains unaffected despite the applied strains and cracks. This favorable stability in phase formation ensures predictability and provides insight into the adaptation of RMS for precision applications in joints. The results expand the understanding of mechanical cracking as a tool to influence high-temperature synthesis in reactive multilayer coatings and provide an opportunity to expand the range of applications.
https://doi.org/10.1002/adem.202302271
Vibration-induced discomfort in vehicles: a comparative evaluation approach for enhancing comfort and ride quality. - In: SAE International journal of vehicle dynamics, stability, and NVH, ISSN 2380-2170, Bd. 8 (2024), 2, 10-08-02-0009, S. 1-15
This article introduces a methodology for conducting comparative evaluations of vibration-induced discomfort. The aim is to outline a procedure specifically focused on assessing and comparing the discomfort caused by vibrations. The article emphasizes the metrics that can effectively quantify vibration-induced discomfort and provides insights on utilizing available information to facilitate the assessment of differences observed during the comparisons. The study also addresses the selection of appropriate target scenarios and test environments within the context of the comparative evaluation procedure. A practical case study is presented, highlighting the comparison of wheel corner concepts in the development of new vehicle architectures. Currently, the evaluation criteria and difference thresholds available allow for comparative evaluations within a limited range of vehicle vibration characteristics.
https://doi.org/10.4271/10-08-02-0009
Toxicity of water-soluble D-g-PNIPAM polymers in a complex with chemotherapy drugs and mechanism of their action in vitro. - In: International journal of molecular sciences, ISSN 1422-0067, Bd. 25 (2024), 5, 3069, S. 1-15
The application of a biocompatible polymer nanocarrier can provide target delivery to tumor tissues, improved pharmacokinetics, controlled drug release, etc. Therefore, the proposed strategy was to use the water-soluble star-like copolymers with a Dextran core and Poly(N-isopropylacrylamide) grafts (D-g-PNIPAM) for conjugation with the widely used chemotherapy drugs in oncology-Cisplatin (Cis-Pt) and Doxorubicin (Dox). The molecular characteristics of the copolymer were received using size-exclusion chromatography. The physicochemical characterization of the D-g-PNIPAM-Cis-Pt (or Dox) nanosystem was conducted using dynamic light scattering and FTIR spectroscopy. Using traditional biochemical methods, a comparative analysis of the enhancement of the cytotoxic effect of free Cis-Pt and Dox in combination with D-g-PNIPAM copolymers was performed in cancer cells of the Lewis lung carcinoma line, which are both sensitive and resistant to Dox; in addition, the mechanism of their action in vitro was evaluated.
https://doi.org/10.3390/ijms25053069